A pilot microdialysis study in brain tumor patients to assess changes in intracerebral cytokine levels after craniotomy and in response to treatment with a targeted anti-cancer agent.

PubMed

Portnow, Jana; Badie, Behnam; Liu, Xueli; Frankel, Paul; Mi, Shu; Chen, Mike; Synold, Timothy W

2014-05-01

Intracerebral microdialysis enables continuous measurement of changes in brain biochemistry. In this study intracerebral microdialysis was used to assess changes in cytokine levels after tumor resection and in response to treatment with temsirolimus. Brain tumor patients undergoing craniotomy participated in this non-therapeutic study. A 100 kDa molecular weight cut-off microdialysis catheter was placed in peritumoral tissue at the time of resection. Cohort 1 underwent craniotomy only. Cohort 2 received a 200 mg dose of intravenous temsirolimus 48 h after surgery. Dialysate samples were collected continuously for 96 h and analyzed for the presence of 30 cytokines. Serial blood samples were collected to measure systemic cytokine levels. Dialysate samples were obtained from six patients in cohort 1 and 4 in cohort 2. Seventeen cytokines could be recovered in dialysate samples from at least 8 of 10 patients. Concentrations of interleukins and chemokines were markedly elevated in peritumoral tissue, and most declined over time, with IL-8, IP-10, MCP-1, MIP1β, IL-6, IL-12p40/p70, MIP1α, IFN-α, G-CSF, IL-2R, and vascular endothelial growth factor significantly (p < 0.05) decreasing over 96 h following surgery. No qualitative changes in intracerebral or serum cytokine concentrations were detected after temsirolimus administration. This is the first intracerebral microdialysis study to evaluate the time course of changes in macromolecule levels in the peritumoral microenvironment after a debulking craniotomy. Initial elevations of peritumoral interleukins and chemokines most likely reflected an inflammatory response to both tumor and surgical trauma. These findings have implications for development of cellular therapies that are administered intracranially at the time of surgery.

Tau elevations in the brain extracellular space correlate with reduced amyloid-β levels and predict adverse clinical outcomes after severe traumatic brain injury.

PubMed

Magnoni, Sandra; Esparza, Thomas J; Conte, Valeria; Carbonara, Marco; Carrabba, Giorgio; Holtzman, David M; Zipfel, Greg J; Stocchetti, Nino; Brody, David L

2012-04-01

Axonal injury is believed to be a major determinant of adverse outcomes following traumatic brain injury. However, it has been difficult to assess acutely the severity of axonal injury in human traumatic brain injury patients. We hypothesized that microdialysis-based measurements of the brain extracellular fluid levels of tau and neurofilament light chain, two low molecular weight axonal proteins, could be helpful in this regard. To test this hypothesis, 100 kDa cut-off microdialysis catheters were placed in 16 patients with severe traumatic brain injury at two neurological/neurosurgical intensive care units. Tau levels in the microdialysis samples were highest early and fell over time in all patients. Initial tau levels were >3-fold higher in patients with microdialysis catheters placed in pericontusional regions than in patients in whom catheters were placed in normal-appearing right frontal lobe tissue (P = 0.005). Tau levels and neurofilament light-chain levels were positively correlated (r = 0.6, P = 0.013). Neurofilament light-chain levels were also higher in patients with pericontusional catheters (P = 0.04). Interestingly, initial tau levels were inversely correlated with initial amyloid-β levels measured in the same samples (r = -0.87, P = 0.000023). This could be due to reduced synaptic activity in areas with substantial axonal injury, as amyloid-β release is closely coupled with synaptic activity. Importantly, high initial tau levels correlated with worse clinical outcomes, as assessed using the Glasgow Outcome Scale 6 months after injury (r = -0.6, P = 0.018). Taken together, our data add support for the hypothesis that axonal injury may be related to long-term impairments following traumatic brain injury. Microdialysis-based measurement of tau levels in the brain extracellular space may be a useful way to assess the severity of axonal injury acutely in the intensive care unit. Further studies with larger numbers of patients will be required to assess the reproducibility of these findings and to determine whether this approach provides added value when combined with clinical and radiological information.

In vivo detection of fluctuating brain steroid levels SHORT

PubMed Central

Ikeda, Maaya; Rensel, Michelle A.; Schlinger, Barney A.; Remage-Healey, Luke

2015-01-01

This protocol describes a method for in vivo measurement of steroid hormones in brain circuits of the zebra finch. In vivo microdialysis has been used successfully to detect fluctuating neurosteroids in the auditory forebrain (Remage-Healey et al., 2008; 2012; Ikeda et al., 2012) and in the hippocampus (Rensel et al., 2012; 2013) of behaving adult zebra finches. In some cases, the steroids measured are derived locally (e.g., ‘neurosteroids’ like estrogens in males) whereas in other cases the steroids measured reflect systemic circulating levels and/or central conversion (e.g., the primary androgen testosterone and the primary glucocorticoid corticosterone). We also describe the method of reverse-microdialysis (‘retrodialysis’) of compounds that can influence local steroid neurochemistry as well as behavior. In vivo microdialysis can now be used to study steroid signaling in the brain for a variety of experimental purposes. Furthermore, similar methods have been developed to examine changing levels of catecholamines in behaving zebra finches (e.g., Sasaki et al., 2006). Thus, the combined study of neurochemistry and behavior in a vocal learning species now has a new set of powerful tools. PMID:25342066

Enhancing Continuous Online Microdialysis Using Dexamethasone: Measurement of Dynamic Neurometabolic Changes during Spreading Depolarization.

PubMed

Varner, Erika L; Leong, Chi Leng; Jaquins-Gerstl, Andrea; Nesbitt, Kathryn M; Boutelle, Martyn G; Michael, Adrian C

2017-08-16

Microdialysis is well established in chemical neuroscience as a mainstay technology for real time intracranial chemical monitoring in both animal models and human patients. Evidence shows that microdialysis can be enhanced by mitigating the penetration injury caused during the insertion of microdialysis probes into brain tissue. Herein, we show that retrodialysis of dexamethasone in the rat cortex enhances the microdialysis detection of K + and glucose transients induced by spreading depolarization. Without dexamethasone, quantification of glucose transients was unreliable by 5 days after probe insertion. With dexamethasone, robust K + and glucose transients were readily quantified at 2 h, 5 days, and 10 days after probe insertion. The amplitudes of the K + transients declined day-to-day following probe insertion, and the amplitudes of the glucose transients exhibited a decreasing trend that did not reach statistical significance. Immunohistochemistry and fluorescence microscopy confirm that dexamethasone is highly effective at preserving a healthy probe-brain interface for at least 10 days even though retrodialysis of dexamethasone ceased after 5 days.

Lactate and the Lactate-to-Pyruvate Molar Ratio Cannot Be Used as Independent Biomarkers for Monitoring Brain Energetic Metabolism: A Microdialysis Study in Patients with Traumatic Brain Injuries

PubMed Central

Sahuquillo, Juan; Merino, Maria-Angels; Sánchez-Guerrero, Angela; Arikan, Fuat; Vidal-Jorge, Marian; Martínez-Valverde, Tamara; Rey, Anna; Riveiro, Marilyn; Poca, Maria-Antonia

2014-01-01

Background For decades, lactate has been considered an excellent biomarker for oxygen limitation and therefore of organ ischemia. The aim of the present study was to evaluate the frequency of increased brain lactate levels and the LP ratio (LPR) in a cohort of patients with severe or moderate traumatic brain injury (TBI) subjected to brain microdialysis monitoring to analyze the agreement between these two biomarkers and to indicate brain energy metabolism dysfunction. Methods Forty-six patients with an admission Glasgow coma scale score of ≤13 after resuscitation admitted to a dedicated 10-bed Neurotraumatology Intensive Care Unit were included, and 5305 verified samples of good microdialysis data were analyzed. Results Lactate levels were above 2.5 mmol/L in 56.9% of the samples. The relationships between lactate and the LPR could not be adequately modeled by any linear or non-linear model. Neither Cohen’s kappa nor Gwet’s statistic showed an acceptable agreement between both biomarkers to classify the samples in regard to normal or abnormal metabolism. The dataset was divided into four patterns defined by the lactate concentrations and the LPR. A potential interpretation for these patterns is suggested and discussed. Pattern 4 (low pyruvate levels) was found in 10.7% of the samples and was characterized by a significantly low concentration of brain glucose compared with the other groups. Conclusions Our study shows that metabolic abnormalities are frequent in the macroscopically normal brain in patients with traumatic brain injuries and a very poor agreement between lactate and the LPR when classifying metabolism. The concentration of lactate in the dialysates must be interpreted while taking into consideration the LPR to distinguish between anaerobic metabolism and aerobic hyperglycolysis. PMID:25025772

Inhibition of P-glycoprotein enhances transport of imipramine across the blood-brain barrier: microdialysis studies in conscious freely moving rats.

PubMed

O'Brien, F E; Clarke, G; Fitzgerald, P; Dinan, T G; Griffin, B T; Cryan, J F

2012-06-01

Recent studies indicate that efflux of antidepressants by the multidrug resistance transporter P-glycoprotein (P-gp) at the blood-brain barrier (BBB) may contribute to treatment-resistant depression (TRD) by limiting intracerebral antidepressant concentrations. In addition, clinical experience shows that adjunctive treatment with the P-gp inhibitor verapamil may improve the clinical outcome in TRD. Therefore, the present study aimed to investigate the effect of P-gp inhibition on the transport of the tricyclic antidepressant imipramine and its active metabolite desipramine across the BBB. Intracerebral microdialysis in rats was used to monitor brain levels of imipramine and desipramine following i.v. imipramine administration, with or without pretreatment with one of the P-gp inhibitors verapamil or cyclosporin A (CsA). Plasma drug levels were also determined at regular intervals. Pretreatment with either verapamil or CsA resulted in significant increases in imipramine concentrations in the microdialysis samples, without altering imipramine plasma pharmacokinetics. Furthermore, pretreatment with verapamil, but not CsA, led to a significant elevation in plasma and brain levels of desipramine. The present study demonstrated that P-gp inhibition enhanced the intracerebral concentration of imipramine , thus supporting the hypothesis that P-gp activity restricts brain levels of certain antidepressants, including imipramine. These findings may help to explain reports of a beneficial response to adjunctive therapy with verapamil in TRD. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

Monitoring vigabatrin in head injury patients by cerebral microdialysis: obtaining pharmacokinetic measurements in a neurocritical care setting

PubMed Central

Shannon, Richard J; Timofeev, Ivan; Nortje, Jürgens; Hutchinson, Peter J; Carpenter, Keri L H

2014-01-01

Aims The aims were to determine blood–brain barrier penetration and brain extracellular pharmacokinetics for the anticonvulsant vigabatrin (VGB; γ-vinyl-γ-aminobutyric acid) in brain extracellular fluid and plasma from severe traumatic brain injury (TBI) patients, and to measure the response of γ-aminobutyric acid (GABA) concentration in brain extracellular fluid. Methods Severe TBI patients (n = 10) received VGB (0.5 g enterally, every 12 h). Each patient had a cerebral microdialysis catheter; two patients had a second catheter in a different region of the brain. Plasma samples were collected 0.5 h before and 2, 4 and 11.5 h after the first VGB dose. Cerebral microdialysis commenced before the first VGB dose and continued through at least three doses of VGB. Controls were seven severe TBI patients with microdialysis, without VGB. Results After the first VGB dose, the maximum concentration of VGB (Cmax) was 31.7 (26.9–42.6) μmol l−1 (median and interquartile range for eight patients) in plasma and 2.41 (2.03–5.94) μmol l−1 in brain microdialysates (nine patients, 11 catheters), without significant plasma–brain correlation. After three doses, median Cmax in microdialysates increased to 5.22 (4.24–7.14) μmol l−1 (eight patients, 10 catheters). Microdialysate VGB concentrations were higher close to focal lesions than in distant sites. Microdialysate GABA concentrations increased modestly in some of the patients after VGB administration. Conclusions Vigabatrin, given enterally to severe TBI patients, crosses the blood–brain barrier into the brain extracellular fluid, where it accumulates with multiple dosing. Pharmacokinetics suggest delayed uptake from the blood. PMID:24802902

Biochemical changes related to hypoxia during cerebral aneurysm surgery: combined microdialysis and tissue oxygen monitoring: case report.

PubMed

Hutchinson, P J; Al-Rawi, P G; O'Connell, M T; Gupta, A K; Pickard, J D; Kirkpatrick, P J

2000-01-01

The objective of this study was to monitor brain metabolism on-line during aneurysm surgery, by combining the use of a multiparameter (brain tissue oxygen, brain carbon dioxide, pH, and temperature) sensor with microdialysis (extracellular glucose, lactate, pyruvate, and glutamate). The case illustrates the potential value of these techniques by demonstrating the effects of adverse physiological events on brain metabolism and the ability to assist in both intraoperative and postoperative decision-making. A 41-year-old woman presented with a World Federation of Neurological Surgeons Grade I subarachnoid hemorrhage. Angiography revealed a basilar artery aneurysm that was not amenable to coiling, so the aneurysm was clipped. Before the craniotomy was performed, a multiparameter sensor and a microdialysis catheter were inserted to monitor brain metabolism. During the operation, the brain oxygen level decreased, in relation to biochemical changes, including the reduction of extracellular glucose and pyruvate and the elevation of lactate and glutamate. These changes were reversible. However, when the craniotomy was closed, a second decrease in brain oxygen occurred in association with brain swelling, which immediately prompted a postoperative computed tomographic scan. The scan demonstrated acute hydrocephalus, requiring external ventricular drainage. The patient made a full recovery. The monitoring techniques influenced clinical decision-making in the treatment of this patient. On-line measurement of brain tissue gases and extracellular chemistry has the potential to assist in the perioperative and postoperative management of patients undergoing complex cerebrovascular surgery and to establish the effects of intervention on brain homeostasis.

Extracellular N-Acetylaspartate in Human Traumatic Brain Injury

PubMed Central

Shannon, Richard J.; Carter, Eleanor L.; Jalloh, Ibrahim; Menon, David K.; Hutchinson, Peter J.; Carpenter, Keri L.H.

2016-01-01

Abstract N-acetylaspartate (NAA) is an amino acid derivative primarily located in the neurons of the adult brain. The function of NAA is incompletely understood. Decrease in brain tissue NAA is presently considered symptomatic and a potential biomarker of acute and chronic neuropathological conditions. The aim of this study was to use microdialysis to investigate the behavior of extracellular NAA (eNAA) levels after traumatic brain injury (TBI). Sampling for this study was performed using cerebral microdialysis catheters (M Dialysis 71) perfused at 0.3 μL/min. Extracellular NAA was measured in microdialysates by high-performance liquid chromatography in 30 patients with severe TBI and for comparison, in radiographically “normal” areas of brain in six non-TBI neurosurgical patients. We established a detailed temporal eNAA profile in eight of the severe TBI patients. Microdialysate concentrations of glucose, lactate, pyruvate, glutamate, and glycerol were measured on an ISCUS clinical microdialysis analyzer. Here, we show that the temporal profile of microdialysate eNAA was characterized by highest levels in the earliest time-points post-injury, followed by a steady decline; beyond 70 h post-injury, average levels were 40% lower than those measured in non-TBI patients. There was a significant inverse correlation between concentrations of eNAA and pyruvate; eNAA showed significant positive correlations with glycerol and the lactate/pyruvate (L/P) ratio measured in microdialysates. The results of this on-going study suggest that changes in eNAA after TBI relate to the release of intracellular components, possibly due to neuronal death or injury, as well as to adverse brain energy metabolism. PMID:26159566

A critical review of 5-HT brain microdialysis and behavior.

PubMed

Rueter, L E; Fornal, C A; Jacobs, B L

1997-01-01

Serotonin (5-HT) has been implicated in many central nervous system-mediated functions including sleep, arousal, feeding, motor activity and the stress response. In order to help establish the precise role of 5-HT in physiology and behavior, in vivo microdialysis studies have sought to identify the conditions under which the release of 5-HT is altered. Extracellular 5-HT levels have been monitored in more than fifteen regions of the brain during a variety of spontaneous behaviors, and in response to several physiological, environmental, and behavioral manipulations. The vast majority of these studies found increases (30-100%) in 5-HT release in almost all brain regions studied. Since electrophysiological studies have shown that behavioral arousal is the primary determinant of brain serotonergic neuronal activity, we suggest that the increase in 5-HT release seen during a wide variety of experimental conditions is largely due to one factor, namely an increase in behavioral arousal/motor activity associated with the manipulation.

In vivo monitoring of neuronal loss in traumatic brain injury: a microdialysis study

PubMed Central

Tisdall, Martin M.; Girbes, Armand R.; Martinian, Lillian; Thom, Maria; Kitchen, Neil; Smith, Martin

2011-01-01

Traumatic brain injury causes diffuse axonal injury and loss of cortical neurons. These features are well recognized histologically, but their in vivo monitoring remains challenging. In vivo cortical microdialysis samples the extracellular fluid adjacent to neurons and axons. Here, we describe a novel neuronal proteolytic pathway and demonstrate the exclusive neuro-axonal expression of Pavlov’s enterokinase. Enterokinase is membrane bound and cleaves the neurofilament heavy chain at positions 476 and 986. Using a 100 kDa microdialysis cut-off membrane the two proteolytic breakdown products, extracellular fluid neurofilament heavy chains NfH476−986 and NfH476−1026, can be quantified with a relative recovery of 20%. In a prospective clinical in vivo study, we included 10 patients with traumatic brain injury with a median Glasgow Coma Score of 9, providing 640 cortical extracellular fluid samples for longitudinal data analysis. Following high-velocity impact traumatic brain injury, microdialysate extracellular fluid neurofilament heavy chain levels were significantly higher (6.18 ± 2.94 ng/ml) and detectable for longer (>4 days) compared with traumatic brain injury secondary to falls (0.84 ± 1.77 ng/ml, <2 days). During the initial 16 h following traumatic brain injury, strong correlations were found between extracellular fluid neurofilament heavy chain levels and physiological parameters (systemic blood pressure, anaerobic cerebral metabolism, excessive brain tissue oxygenation, elevated brain temperature). Finally, extracellular fluid neurofilament heavy chain levels were of prognostic value, predicting mortality with an odds ratio of 7.68 (confidence interval 2.15–27.46, P = 0.001). In conclusion, this study describes the discovery of Pavlov’s enterokinase in the human brain, a novel neuronal proteolytic pathway that gives rise to specific protein biomarkers (NfH476−986 and NfH476−1026) applicable to in vivo monitoring of diffuse axonal injury and neuronal loss in traumatic brain injury. PMID:21278408

Vitamin D receptor activation induces P-glycoprotein and increases brain efflux of quinidine: an intracerebral microdialysis study in conscious rats.

PubMed

Durk, Matthew R; Fan, Jianghong; Sun, Huadong; Yang, Yingbo; Pang, Henrianna; Pang, K Sandy; de Lannoy, Inés A M

2015-03-01

Since the vitamin D receptor (VDR) was found to up-regulate cerebral P-glycoprotein expression in vitro and in mice, we extend our findings to rats by assessing the effect of rat Vdr activation on brain efflux of quinidine, a P-gp substrate that is eliminated primarily by cytochrome P450 3a. We treated rats with vehicle or the active VDR ligand, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] (4.8 or 6.4 nmol/kg i.p. every 2nd day × 4) and examined P-gp expression and cerebral quinidine disposition via microdialysis in control and treatment studies conducted longitudinally in the same rat. The 6.4 nmol/kg 1,25(OH)2D3 dose increased cerebral P-gp expression 1.75-fold whereas hepatic Cyp3a remained unchanged. Although there was no change in systemic clearance elicited by 1,25(OH)2D3, brain extracellular fluid quinidine concentrations were lower in treated rats. We noted that insertion of indwelling catheters increased plasma protein binding of quinidine and serial sampling decreased the blood:plasma concentration ratio, factors that alter distribution ratios in microdialysis studies. After appropriate correction, KECF/P,uu and KECF/B,uu, or ratios of quinidine unbound concentrations in brain extracellular fluid to plasma or blood at steady-state, were more than halved. We demonstrate that VDR activation increases cerebral P-gp expression and delimits brain penetration of P-gp substrates.

Overview of Brain Microdialysis

PubMed Central

Chefer, Vladimir I.; Thompson, Alexis C.; Zapata, Agustin; Shippenberg, Toni S.

2010-01-01

The technique of microdialysis enables sampling and collecting of small-molecular-weight substances from the interstitial space. It is a widely used method in neuroscience and is one of the few techniques available that permits quantification of neurotransmitters, peptides, and hormones in the behaving animal. More recently, it has been used in tissue preparations for quantification of neurotransmitter release. This unit provides a brief review of the history of microdialysis and its general application in the neurosciences. The authors review the theoretical principles underlying the microdialysis process, methods available for estimating extracellular concentration from dialysis samples (i.e., relative recovery), the various factors that affect the estimate of in vivo relative recovery, and the importance of determining in vivo relative recovery to data interpretation. Several areas of special note, including impact of tissue trauma on the interpretation of microdialysis results, are discussed. Step-by-step instructions for the planning and execution of conventional and quantitative microdialysis experiments are provided. PMID:19340812

In Vivo Microdialysis and Electroencephalographic Activity in Freely Moving Guinea Pigs Exposed to Organophosphorus Nerve Agents Sarin and VX: Analysis of Acetylcholine and Glutamate

DTIC Science & Technology

2011-01-01

3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE In vivo microdialysis and electroencephalographic activity in freely moving guinea pigs 5a...microdialysis and electroencephalographic activity in freely moving guinea pigs exposed to organophosphorus nerve agents sarin and VX: analysis of...brain seizure activity . This robust double multi- variate design provides greater fidelity when comparing data while also reducing the required number

Physiologically Relevant Changes in Serotonin Resolved by Fast Microdialysis

PubMed Central

2013-01-01

Online microdialysis is a sampling and detection method that enables continuous interrogation of extracellular molecules in freely moving subjects under behaviorally relevant conditions. A majority of recent publications using brain microdialysis in rodents report sample collection times of 20–30 min. These long sampling times are due, in part, to limitations in the detection sensitivity of high performance liquid chromatography (HPLC). By optimizing separation and detection conditions, we decreased the retention time of serotonin to 2.5 min and the detection threshold to 0.8 fmol. Sampling times were consequently reduced from 20 to 3 min per sample for online detection of serotonin (and dopamine) in brain dialysates using a commercial HPLC system. We developed a strategy to collect and to analyze dialysate samples continuously from two animals in tandem using the same instrument. Improvements in temporal resolution enabled elucidation of rapid changes in extracellular serotonin levels associated with mild stress and circadian rhythms. These dynamics would be difficult or impossible to differentiate using conventional microdialysis sampling rates. PMID:23614776

Monitoring vigabatrin in head injury patients by cerebral microdialysis: obtaining pharmacokinetic measurements in a neurocritical care setting.

PubMed

Shannon, Richard J; Timofeev, Ivan; Nortje, Jürgens; Hutchinson, Peter J; Carpenter, Keri L H

2014-11-01

The aims were to determine blood-brain barrier penetration and brain extracellular pharmacokinetics for the anticonvulsant vigabatrin (VGB; γ-vinyl-γ-aminobutyric acid) in brain extracellular fluid and plasma from severe traumatic brain injury (TBI) patients, and to measure the response of γ-aminobutyric acid (GABA) concentration in brain extracellular fluid. Severe TBI patients (n = 10) received VGB (0.5 g enterally, every 12 h). Each patient had a cerebral microdialysis catheter; two patients had a second catheter in a different region of the brain. Plasma samples were collected 0.5 h before and 2, 4 and 11.5 h after the first VGB dose. Cerebral microdialysis commenced before the first VGB dose and continued through at least three doses of VGB. Controls were seven severe TBI patients with microdialysis, without VGB. After the first VGB dose, the maximum concentration of VGB (Cmax ) was 31.7 (26.9-42.6) μmol l(-1) (median and interquartile range for eight patients) in plasma and 2.41 (2.03-5.94) μmol l(-1) in brain microdialysates (nine patients, 11 catheters), without significant plasma-brain correlation. After three doses, median Cmax in microdialysates increased to 5.22 (4.24-7.14) μmol l(-1) (eight patients, 10 catheters). Microdialysate VGB concentrations were higher close to focal lesions than in distant sites. Microdialysate GABA concentrations increased modestly in some of the patients after VGB administration. Vigabatrin, given enterally to severe TBI patients, crosses the blood-brain barrier into the brain extracellular fluid, where it accumulates with multiple dosing. Pharmacokinetics suggest delayed uptake from the blood. © 2014 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of The British Pharmacological Society.

Lack of utility of arteriojugular venous differences of lactate as a reliable indicator of increased brain anaerobic metabolism in traumatic brain injury.

PubMed

Poca, Maria A; Sahuquillo, Juan; Vilalta, Anna; Garnacho, Angel

2007-04-01

Ischemic lesions are highly prevalent in patients with traumatic brain injuries (TBIs) and are the single most important cause of secondary brain damage. The prevention and early treatment of these lesions is the primary aim in the modem treatment of these patients. One of the most widely used monitoring techniques at the bedside is quantification of brain extracellular level of lactate by using arteriojugular venous differences of lactate (AVDL). The purpose of this study was to determine the sensitivity, specificity, and predictive value of AVDL as an indicator of increases in brain lactate production in patients with TBIs. Arteriojugular venous differences of lactate were calculated every 6 hours using samples obtained though a catheter placed in the jugular bulb in 45 patients with diffuse head injuries (57.8%) or evacuated brain lesions (42.2%). Cerebral lactate concentration obtained with a 20-kD microdialysis catheter implanted in undamaged tissue was used as the de facto gold standard. Six hundred seventy-three AVDL determinations and cerebral microdialysis samples were obtained simultaneously; 543 microdialysis samples (81%) showed lactate values greater than 2 mmol/L, but only 21 AVDL determinations (3.1%) showed an increase in brain lactate. No correlation was found between AVDL and cerebral lactate concentration (p = 0.014, p = 0.719). Arteriojugular venous differences of lactate had a sensitivity and specificity of 3.3 and 97.7%, respectively, with a false-negative rate of 96.7% and a false-positive rate of 2.3%. Arteriojugular venous differences of lactate do not reliably reflect increased cerebral lactate production and consequently are not reliable in ruling out brain ischemia in patients with TBIs. The clinical use of this monitoring method in neurocritical care should be reconsidered.

Cerebral Glucose Metabolism and Sedation in Brain-injured Patients: A Microdialysis Study.

PubMed

Hertle, Daniel N; Santos, Edgar; Hagenston, Anna M; Jungk, Christine; Haux, Daniel; Unterberg, Andreas W; Sakowitz, Oliver W

2015-07-01

Disturbed brain metabolism is a signature of primary damage and/or precipitates secondary injury processes after severe brain injury. Sedatives and analgesics target electrophysiological functioning and are as such well-known modulators of brain energy metabolism. Still unclear, however, is how sedatives impact glucose metabolism and whether they differentially influence brain metabolism in normally active, healthy brain and critically impaired, injured brain. We therefore examined and compared the effects of anesthetic drugs under both critical (<1 mmol/L) and noncritical (>1 mmol/L) extracellular brain glucose levels. We performed an explorative, retrospective analysis of anesthetic drug administration and brain glucose concentrations, obtained by bedside microdialysis, in 19 brain-injured patients. Our investigations revealed an inverse linear correlation between brain glucose and both the concentration of extracellular glutamate (Pearson r=-0.58, P=0.01) and the lactate/glucose ratio (Pearson r=-0.55, P=0.01). For noncritical brain glucose levels, we observed a positive linear correlation between midazolam dose and brain glucose (P<0.05). For critical brain glucose levels, extracellular brain glucose was unaffected by any type of sedative. These findings suggest that the use of anesthetic drugs may be of limited value in attempts to influence brain glucose metabolism in injured brain tissue.

Determination of Serotonin and Dopamine Metabolites in Human Brain Microdialysis and Cerebrospinal Fluid Samples by UPLC-MS/MS: Discovery of Intact Glucuronide and Sulfate Conjugates

PubMed Central

Suominen, Tina; Uutela, Päivi; Ketola, Raimo A.; Bergquist, Jonas; Hillered, Lars; Finel, Moshe; Zhang, Hongbo; Laakso, Aki; Kostiainen, Risto

2013-01-01

An UPLC-MS/MS method was developed for the determination of serotonin (5-HT), dopamine (DA), their phase I metabolites 5-HIAA, DOPAC and HVA, and their sulfate and glucuronide conjugates in human brain microdialysis samples obtained from two patients with acute brain injuries, ventricular cerebrospinal fluid (CSF) samples obtained from four patients with obstructive hydrocephalus, and a lumbar CSF sample pooled mainly from patients undergoing spinal anesthesia in preparation for orthopedic surgery. The method was validated by determining the limits of detection and quantification, linearity, repeatability and specificity. The direct method enabled the analysis of the intact phase II metabolites of 5-HT and DA, without hydrolysis of the conjugates. The method also enabled the analysis of the regioisomers of the conjugates, and several intact glucuronide and sulfate conjugates were identified and quantified for the first time in the human brain microdialysis and CSF samples. We were able to show the presence of 5-HIAA sulfate, and that dopamine-3-O-sulfate predominates over dopamine-4-O-sulfate in the human brain. The quantitative results suggest that sulfonation is a more important phase II metabolism pathway than glucuronidation in the human brain. PMID:23826355

Cortical damage following traumatic brain injury evaluated by iomazenil SPECT and in vivo microdialysis.

PubMed

Koizumi, Hiroyasu; Fujisawa, Hirosuke; Suehiro, Eiichi; Iwanaga, Hideyuki; Nakagawara, Jyoji; Suzuki, Michiyasu

2013-01-01

[(123)I] iomazenil (IMZ) single photon emission computed tomography (SPECT) has been reported to be a useful marker of neuronal integrity. We evaluated cortical damage following traumatic brain injury (TBI) with IMZ SPECT at the acute stage. After conventional therapy for a cranial trauma, an IMZ SPECT re-evaluation was performed at the chronic stage. A reduction in IMZ uptake in the location of cerebral contusions was observed during the TBI acute phase; however, images of IMZ SPECT obtained during the chronic phase showed that areas with decreased IMZ distribution were remarkably reduced compared with those obtained during the acute phase. As a result of in vivo microdialysis study, the extracellular levels of glutamate in the cortex, where decreased IMZ distribution was shown during the acute phase, were increased during the 168-h monitoring period. During the chronic phase, IMZ uptake in the region with the microdialysis probes was recovered. The results suggest that this reduction in IMZ uptake might not be a sign of irreversible tissue damage in TBI.

LC-MS/MS method for the quantification of almotriptan in dialysates: application to rat brain and blood microdialysis study.

PubMed

Nirogi, Ramakrishna; Ajjala, Devender Reddy; Kandikere, Vishwottam; Aleti, Raghupathi; Pantangi, Hanumanth Rao; Srikakolapu, Surya Rao; Benade, Vijay; Bhyrapuneni, Gopinadh; Vurimindi, Himabindu

2013-01-01

A sensitive LC-MS/MS method was developed and validated for the quantification of almotriptan in rat brain and blood dialysates. Almotriptan is a 5HT1B/1D receptor agonist used for the treatment of migraine pain. Method consists of rapid gradient elution program with 10mM ammonium formate (pH 3) and acetonitrile on a Xbridge column. The MRM transitions monitored were m/z 336.2-58.1 for almotriptan and m/z 448.2-285.3 for the IS. The assay was linear in the range of 0.1-20 ng/ml, with acceptable precision and accuracy along with adequate sensitivity. The between batch accuracy was in the range of 99.0-104.3% with precision in between 0.6% and 5.8%. Microdialysis is an important sampling technique, with the capability of capturing the concentrations of various analytes in different bio fluids, at a single time point. This method was applied to quantify brain and blood dialysate samples obtained from a microdialysis study of rats treated with almotriptan (10mg/kg, p.o.). In vivo recovery experiments were performed to correct the dialysate concentrations into extracellular concentrations. Mean peak dialysate concentrations of almotriptan were found to be 152 ± 78 and 7.4 ± 1.0 ng/ml in blood and prefrontal cortex, respectively. The brain penetration of almotriptan is characterized by the AUCbrain/AUCblood found to be 0.07 ± 0.05. The results revealed the importance of measuring the unbound almotriptan concentrations in the brain over the blood for understanding its PK/PD relationship. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of variation in cerebral haemodynamics during aneurysm surgery on brain tissue oxygen and metabolism.

PubMed

Kett-White, R; Hutchinson, P J; Czosnyka, M; al-Rawi, P; Gupta, A; Pickard, J D; Kirkpatrick, P J

2002-01-01

This study explores the sensitivities of multiparameter tissue gas sensors and microdialysis to variations in blood pressure, CSF drainage and to well-defined periods of ischaemia accompanying aneurysm surgery, and their predictive value for infarction. A Neurotrend sensor [brain tissue partial pressure of oxygen (PBO2), carbon dioxide (PBCO2), brain pH (pHB) and temperature] and microdialysis catheter were inserted into the appropriate vascular territory prior to craniotomy. Baseline data showed a clear correlation between PBO2 and mean arterial pressure (MAP) below a threshold of 80 mmHg. PBO2 improved with CSF drainage in 20 out of 28 (Wilcoxon: P < 0.05) cases where data was available. In 26 patients the effects of temporary vascular clipping (TC) (mean duration 16 minutes) were assessed. 2 patients subsequently declared infarction in the region of the probes. PBO2 fell from a mean 3.2 (95% CI 2.4-4.1) kPa to a minimum of 1.5 (95% CI 1.0-2.0) kPa in the non-infarct group. There was a lower baseline PBO2 (mean 0.8 kPa) in the patients who infarcted. PBCO2 mirrored PBO2 changes, whereas pHB did not change significantly in either group. Microdialysis changes associated with decreased PBO2 included a delayed increase in lactate, a raised lactate/pyruvate ratio and more rarely an increased glutamate. These changes were seen in 11 patients but were not predictive of infarction. Hypotension during aneurysm surgery is associated with a low PBO2. Multiparameter sensors can be sensitive to acute ischaemia. Microdialysis shows potential in the detection of metabolic changes during tissue hypoxia.

Microdialysis pharmacokinetic study of scopolamine in plasma, olfactory bulb and vestibule after intranasal administration.

PubMed

Wei, Yan; Ying, Mingzhen; Xu, Shuai; Wang, Feng; Zou, Aifeng; Cao, Shilei; Jiang, Xinguo; Wang, Yajie

2016-01-01

The purpose of this study was to investigate the microdialysis pharmacokinetic of scopolamine in plasma, olfactory bulb and vestibule after intranasal administration. The pharmacokinetic study of subcutaneous and oral administration was also performed in rats. From the in vivo results, scopolamine intranasal administration can avoid hepatic first-pass effect. Tmax plasma samples after intranasal administration were significantly faster than oral administration and subcutaneous injection. The relative bioavailability of intranasal administrations was 51.8-70% when compared with subcutaneous injection. Moreover, one can see that in comparison with scopolamine subcutaneous administration, scopolamine intranasal gel and solutions can increased drug target index (DTI) with olfactory bulb 1.69 and 2.05, vestibule 1.80 and 2.15, respectively. The results indicated that scopolamine can be absorbed directly through the olfactory mucosa into the olfactory bulb, and then transported to various brain tissue after intranasal administration, with the characteristics of brain drug delivery.

Evaluation of a Portable Microchip Electrophoresis Fluorescence Detection System for the Analysis of Amino Acid Neurotransmitters in Brain Dialysis Samples

PubMed Central

OBORNY, Nathan J.; COSTA, Elton E. Melo; SUNTORNSUK, Leena; ABREU, Fabiane C.; LUNTE, Susan M.

2016-01-01

A portable fluorescence detection system for use with microchip electrophoresis was developed and compared to a benchtop system. Using this system, six neuroactive amines commonly found in brain dialysate—arginine, citrulline, taurine, histamine, glutamate, and aspartate—were derivatized offline with naphthalene-2,3-dicarboxaldehyde/cyanide, separated electrophoretically, and detected by fluorescence. Limits of detection for the analytes of interest were 50nM – 250nM for the benchtop system and 250 nM – 1.3 μM for the portable system, both of which were adequate for analyte determination in brain microdialysis samples. The portable system was then demonstrated for the detection of the same six amines in a rat brain microdialysis sample. PMID:26753703

Age-dependent changes at the blood-brain barrier. A Comparative structural and functional study in young adult and middle aged rats.

PubMed

Bors, Luca; Tóth, Kinga; Tóth, Estilla Zsófia; Bajza, Ágnes; Csorba, Attila; Szigeti, Krisztián; Máthé, Domokos; Perlaki, Gábor; Orsi, Gergely; Tóth, Gábor K; Erdő, Franciska

2018-05-01

Decreased beta-amyloid clearance in Alzheimer's disease and increased blood-brain barrier permeability in aged subjects have been reported in several articles. However, morphological and functional characterization of blood-brain barrier and its membrane transporter activity have not been described in physiological aging yet. The aim of our study was to explore the structural changes in the brain microvessels and possible functional alterations of P-glycoprotein at the blood-brain barrier with aging. Our approach included MR imaging for anatomical orientation in middle aged rats, electronmicroscopy and immunohistochemistry to analyse the alterations at cellular level, dual or triple-probe microdialysis and SPECT to test P-glycoprotein functionality in young and middle aged rats. Our results indicate that the thickness of basal lamina increases, the number of tight junctions decreases and the size of astrocyte endfeet extends with advanced age. On the basis of microdialysis and SPECT results the P-gp function is reduced in old rats. With our multiparametric approach a complex regulation can be suggested which includes elements leading to increased permeability of blood-brain barrier by enhanced paracellular and transcellular transport, and factors working against it. To verify the role of P-gp pumps in brain aging further studies are warranted. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

In vivo assessment of high-grade glioma biochemistry using microdialysis: a study of energy-related molecules, growth factors and cytokines.

PubMed

Marcus, Hani J; Carpenter, Keri L H; Price, Stephen J; Hutchinson, Peter J

2010-03-01

Microdialysis enables measurement of the chemistry of the cerebral extracellular fluid. This study's objective was to utilise microdialysis to monitor levels of glucose, lactate, pyruvate, glutamate and glycerol in patients following surgery for intrinsic brain tumours, and to assess the concentration of growth factors, cytokines and other proteins involved in the pathogenesis of high-grade gliomas in vivo. Eight patients with suspected high-grade gliomas were studied. Seven of these underwent resection with one microdialysis catheter placed at the tumour resection margin and, in six of these seven cases, a second microdialysis catheter in macroscopically normal peritumour tissue. The remaining glioma patient had an image-guided biopsy with a single catheter inserted stereotactically at the tumour margin. Histology demonstrated WHO IV glioblastoma in five cases, WHO III anaplastic astrocytoma in two cases, and one cerebral lymphoma. In the high-grade gliomas (WHO IV and III), tumour margin microdialysates consistently showed significantly lower glucose, higher lactate/pyruvate (L/P) ratio, higher glutamate and higher glycerol, relative to peritumour microdialysates (P < 0.05). These results indicate that malignant glioma margin tissue is metabolically extremely active. There was great variability in the microdialysate concentrations of growth factors (TGFalpha, EGF, VEGF), cytokines (IL-1alpha, IL-1beta, IL-1ra, IL-6, IL-8), matrix metalloproteinases (MMP-2, MMP-9) and their endogenous inhibitors (TIMP-1, TIMP-2). Notably, microdialysates from the glioma resection margin demonstrated significantly higher IL-8 concentration and higher MMP-2/TIMP-1 ratio when compared to peritumour microdialysates (P < 0.05), suggesting an environment favouring invasion and angiogenesis at the tumour margin. Microdialysis is a promising technique to study in vivo glioma metabolism, and may assist in the development of new therapies.

Agmatine reduces extracellular glutamate during pentylenetetrazole-induced seizures in rat brain: A potential mechanism for the anticonvulsive effects

PubMed Central

Feng, Yangzheng; LeBlanc, Michael H.; Regunathan, Soundar

2010-01-01

Glutamate has been implicated in the initiation and spread of seizure activity. Agmatine, an endogenous neuromodulator, is an antagonist of NMDA receptors and has anticonvulsive effects. Whether agmatine regulate glutamate release, as measured by in vivo microdialysis, is not known. In this study, we used pentylenetetrazole (PTZ)-induced seizure model to determine the effect of agmatine on extracellular glutamate in rat brain. We also determined the time course and the amount of agmatine that reached brain after peripheral injection. After i.p. injection of agmatine (50 mg/kg), increase of agmatine in rat cortex and hippocampus was observed in 15 min with levels returning to baseline in one hour. Rats, naïve and implanted with microdialysis cannula into the cortex, were administered PTZ (60 mg/kg, i.p.) with prior injection of agmatine (100 mg/kg, i.p.) or saline. Seizure grades were recorded and microdialysis samples were collected every 15 min for 75 min. Agmatine pre-treatment significantly reduced the seizure grade and increased the onset time. The levels of extracellular glutamate in frontal cortex rose two- to three-fold after PTZ injection and agmatine significantly inhibited this increase. In conclusion, the present data suggest that the anticonvulsant activity of agmatine, in part, could be related to the inhibition glutamate release. PMID:16125317

Determination of protein-unbound rhynchiphylline brain distribution by microdialysis and ultra-performance liquid chromatography with tandem mass spectrometry.

PubMed

Lee, Chia-Jung; Hsueh, Thomas Y; Lin, Lie-Chwen; Tsai, Tung-Hu

2014-06-01

The stem with hook of Uncaria rhynchophylla (Chinese herbal name Gou-Teng) is a traditional Chinese medicine that has been ethnopharmacologically used to extinguish wind and clean interior heat. Rhynchophylline (RHY), a tetracyclic oxindole alkaloid isolated from U. rhynchophylla, displays significant antineuroinflammatory effects. However, there is no evidence to indicate that rhynchophylline can cross the blood-brain barrier and be detected in the brain. In this study, an in vivo microdialysis sampling method coupled with UPLC/MS/MS was employed for the continuous simultaneous monitoring of unbound RHY in rat blood and brain. The precursor ion → product ion transition at m/z 385.2 → 160.0 for rhynchophylline was monitored. A calibration curve gave good linearity (r>0.996) over the concentration range from 0.5 to 1000 ng/mL. The results demonstrated that rhynchophylline could be detected in the brain and plasma from 15 min to 6 h after its administration (1 or 10 mg/kg, i.v.). All the pharmacokinetic parameters of rhynchophylline in the brain and plasma were obtained. These results show that rhynchophylline can cross the blood-brain barrier and they provide useful clinical information. Copyright © 2014 John Wiley & Sons, Ltd.

Revisiting atenolol as a low passive permeability marker.

PubMed

Chen, Xiaomei; Slättengren, Tim; de Lange, Elizabeth C M; Smith, David E; Hammarlund-Udenaes, Margareta

2017-10-31

Atenolol, a hydrophilic beta blocker, has been used as a model drug for studying passive permeability of biological membranes such as the blood-brain barrier (BBB) and the intestinal epithelium. However, the extent of S-atenolol (the active enantiomer) distribution in brain has never been evaluated, at equilibrium, to confirm that no transporters are involved in its transport at the BBB. To assess whether S-atenolol, in fact, depicts the characteristics of a low passive permeable drug at the BBB, a microdialysis study was performed in rats to monitor the unbound concentrations of S-atenolol in brain extracellular fluid (ECF) and plasma during and after intravenous infusion. A pharmacokinetic model was developed, based on the microdialysis data, to estimate the permeability clearance of S-atenolol into and out of brain. In addition, the nonspecific binding of S-atenolol in brain homogenate was evaluated using equilibrium dialysis. The steady-state ratio of unbound S-atenolol concentrations in brain ECF to that in plasma (i.e., K p,uu,brain ) was 3.5% ± 0.4%, a value much less than unity. The unbound volume of distribution in brain (V u, brain ) of S-atenolol was also calculated as 0.69 ± 0.10 mL/g brain, indicating that S-atenolol is evenly distributed within brain parenchyma. Lastly, equilibrium dialysis showed limited nonspecific binding of S-atenolol in brain homogenate with an unbound fraction (f u,brain ) of 0.88 ± 0.07. It is concluded, based on K p,uu,brain being much smaller than unity, that S-atenolol is actively effluxed at the BBB, indicating the need to re-consider S-atenolol as a model drug for passive permeability studies of BBB transport or intestinal absorption.

Feeding-associated alterations in striatal neurotransmitter release

NASA Technical Reports Server (NTRS)

Acworth, I. N.; Ressler, K.; Wurtman, R. J.

1989-01-01

Published evidence suggests a role for dopaminergic (DA) brain pathways in feeding-associated behaviors. Using the novel technique of brain microdialysis of striatal extracellular fluid (ECF) as an index of DA release, Church et al. described increases in levels of DA when animals had limited access to pellets, but not with free access. Dopamine release from the nucleus accumbens did increase with free access to pellets post starvation or after food reward. We used permanently implanted microdialysis probes to measure ECF levels of DA, DOPAC, HVA, and large neutral amino acids (LNAA) for up to 72 hours after implantation among rats experiencing different dietary regimens.

Brain interstitial fluid TNF-α after subarachnoid hemorrhage

PubMed Central

Hanafy, Khalid A.; Grobelny, Bartosz; Fernandez, Luis; Kurtz, Pedro; Connolly, ES; Mayer, Stephan A.; Schindler, Christian; Badjatia, Neeraj

2010-01-01

Objective: TNF-α is an inflammatory cytokine that plays a central role in promoting the cascade of events leading to an inflammatory response. Recent studies have suggested that TNF-α may play a key role in the formation and rupture of cerebral aneurysms, and that the underlying cerebral inflammatory response is a major determinate of outcome following subrarachnoid hemorrhage (SAH). Methods: We studied 14 comatose SAH patients who underwent multimodality neuromonitoring with intracranial pressure (ICP) and cerebral microdialysis as part of their clinical care. Continuous physiological variables were time-locked every 8 hours and recorded at the same point that brain interstitial fluid TNF-α was measured in brain microdialysis samples. Significant associations were determined using generalized estimation equations. Results: Each patient had a mean of 9 brain tissue TNF-α measurements obtained over an average of 72 hours of monitoring. TNF-α levels rose progressively over time. Predictors of elevated brain interstitial TNF-α included higher brain interstitial fluid glucose levels (β=0.066, P<0.02), intraventricular hemorrhage (β=0.085, P<0.021), and aneurysm size >6 mm (β=0.14, p<0.001). There was no relationship between TNF-α levels and the burden of cisternal SAH; concurrent measurements of serum glucose, or lactate-pyruvate ratio. Interpretation: Brain interstitial TNF-α levels are elevated after SAH, and are associated with large aneurysm size, the burden of intraventricular blood, and elevation brain interstitial glucose levels. PMID:20110094

Glycolysis and the pentose phosphate pathway after human traumatic brain injury: microdialysis studies using 1,2-13C2 glucose

PubMed Central

Jalloh, Ibrahim; Carpenter, Keri L H; Grice, Peter; Howe, Duncan J; Mason, Andrew; Gallagher, Clare N; Helmy, Adel; Murphy, Michael P; Menon, David K; Carpenter, T Adrian; Pickard, John D; Hutchinson, Peter J

2015-01-01

Increased ‘anaerobic' glucose metabolism is observed after traumatic brain injury (TBI) attributed to increased glycolysis. An alternative route is the pentose phosphate pathway (PPP), which generates putatively protective and reparative molecules. To compare pathways we employed microdialysis to perfuse 1,2-13C2 glucose into the brains of 15 TBI patients and macroscopically normal brain in six patients undergoing surgery for benign tumors, and to simultaneously collect products for nuclear magnetic resonance (NMR) analysis. 13C enrichment for glycolytic 2,3-13C2 lactate was the median 5.4% (interquartile range (IQR) 4.6–7.5%) in TBI brain and 4.2% (2.4–4.4%) in ‘normal' brain (P<0.01). The ratio of PPP-derived 3-13C lactate to glycolytic 2,3-13C2 lactate was median 4.9% (3.6–8.2%) in TBI brain and 6.7% (6.3–8.9%) in ‘normal' brain. An inverse relationship was seen for PPP-glycolytic lactate ratio versus PbtO2 (r=−0.5, P=0.04) in TBI brain. Thus, glycolytic lactate production was significantly greater in TBI than ‘normal' brain. Several TBI patients exhibited PPP–lactate elevation above the ‘normal' range. There was proportionally greater PPP-derived lactate production with decreasing PbtO2. The study raises questions about the roles of the PPP and glycolysis after TBI, and whether they can be manipulated to achieve a better outcome. This study is the first direct comparison of glycolysis and PPP in human brain. PMID:25335801

The Brain In Vivo Expresses the 2′,3′-cAMP-Adenosine Pathway

PubMed Central

Verrier, Jonathan D.; Jackson, Travis C.; Bansal, Rashmi; Kochanek, Patrick M.; Puccio, Ava M.; Okonkwo, David O.; Jackson, Edwin K.

2012-01-01

Although multiple biochemical pathways produce adenosine, studies suggest that the 2′,3′-cAMP-adenosine pathway (2′,3′-cAMP → 2′-AMP/3′-AMP → adenosine) contributes to adenosine production in some cells/tissues/organs. To determine whether the 2′,3′-cAMP-adenosine pathway exists in vivo in the brain, we delivered to the brain (gray matter and white matter separately) via the inflow perfusate of a microdialysis probe either 2′,3′-cAMP, 3′,5′-cAMP, 2′-AMP, 3′-AMP, or 5′-AMP and measured the recovered metabolites in the microdialysis outflow perfusate with mass spectrometry. In both gray and white matter, 2′,3′-cAMP increased 2′-AMP, 3′-AMP and adenosine, and 3′,5′-cAMP increased 5′-AMP and adenosine. In both brain regions, 2′-AMP, 3-AMP and 5′-AMP were converted to adenosine. Microdialysis experiments in 2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) wild-type mice demonstrated that traumatic brain injury (TBI; controlled cortical impact model) activated the brain 2,3′-cAMP-adenosine pathway; similar experiments in CNPase knockout mice indicated that CNPase was involved in the metabolism of endogenous 2′,3′-cAMP to 2′-AMP and to adenosine. In CSF from TBI patients, 2′,3′-cAMP was significantly increased in the initial 12 hours after injury and strongly correlated with CSF levels of 2′-AMP, 3′-AMP, adenosine and inosine. We conclude that in vivo, 2′,3′-cAMP is converted to 2′-AMP/3′-AMP, and these AMPs are metabolized to adenosine. This pathway exists endogenously in both mice and humans. PMID:22360621

Novel codrugs with GABAergic activity for dopamine delivery in the brain.

PubMed

Denora, Nunzio; Cassano, Tommaso; Laquintana, Valentino; Lopalco, Antonio; Trapani, Adriana; Cimmino, Concetta Stefania; Laconca, Leonardo; Giuffrida, Andrea; Trapani, Giuseppe

2012-11-01

This study investigates the use of codrugs of the GABAergic agent 2-phenyl-imidazo[1,2-a]pyridinacetamide and dopamine (DA) or ethyl ester L-Dopa (LD) as a strategy to deliver DA and simultaneously activate GABA-receptors in the brain. For this purpose, both DA and LD ethyl ester were linked by carbamate bond to imidazo[1,2-a]pyridine acetamide moieties to yield two DA- and two LD-imidazopyridine derivatives. These compounds were evaluated in vitro to assess their stability, binding affinities and cell membrane transport, and in vivo to assess their bio-availability via microdialysis studies. The two DA derivatives were adequately stable in buffered solution, but underwent cleavage in diluted human serum. By contrast, the LD derivatives were unstable in buffered solution. Receptor binding studies showed that the DA-imidazopyridine carbamates had binding affinity for benzodiazepine receptors in the nanomolar range. Brain microdialysis experiments indicated that intraperitoneal administration of the DA derivatives sustained DA levels in rat striatum over a 4-h period. These results suggest that DA-imidazopyridine carbamates are new DA codrugs with potential application for DA replacement therapy. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of peptide transporter 2 (PEPT2) on the distribution of cefadroxil in mouse brain: A microdialysis study.

PubMed

Chen, Xiaomei; Keep, Richard F; Liang, Yan; Zhu, Hao-Jie; Hammarlund-Udenaes, Margareta; Hu, Yongjun; Smith, David E

2017-05-01

Peptide transporter 2 (PEPT2) is a high-affinity low-capacity transporter belonging to the proton-coupled oligopeptide transporter family. Although many aspects of PEPT2 structure-function are known, including its localization in choroid plexus and neurons, its regional activity in brain, especially extracellular fluid (ECF), is uncertain. In this study, the pharmacokinetics and regional brain distribution of cefadroxil, a β-lactam antibiotic and PEPT2 substrate, were investigated in wildtype and Pept2 null mice using in vivo intracerebral microdialysis. Cefadroxil was infused intravenously over 4h at 0.15mg/min/kg, and samples obtained from plasma, brain ECF, cerebrospinal fluid (CSF) and brain tissue. A permeability-surface area experiment was also performed in which 0.15mg/min/kg cefadroxil was infused intravenously for 10min, and samples obtained from plasma and brain tissues. Our results showed that PEPT2 ablation significantly increased the brain ECF and CSF levels of cefadroxil (2- to 2.5-fold). In contrast, there were no significant differences between wildtype and Pept2 null mice in the amount of cefadroxil in brain cells. The unbound volume of distribution of cefadroxil in brain was 60% lower in Pept2 null mice indicating an uptake function for PEPT2 in brain cells. Finally, PEPT2 did not affect the influx clearance of cefadroxil, thereby, ruling out differences between the two genotypes in drug entry across the blood-brain barriers. These findings demonstrate, for the first time, the impact of PEPT2 on brain ECF as well as the known role of PEPT2 in removing peptide-like drugs, such as cefadroxil, from the CSF to blood. Copyright © 2017 Elsevier Inc. All rights reserved.

The neuropharmacokinetics of temozolomide in patients with resectable brain tumors: potential implications for the current approach to chemoradiation.

PubMed

Portnow, Jana; Badie, Behnam; Chen, Mike; Liu, An; Blanchard, Suzette; Synold, Timothy W

2009-11-15

Intracerebral microdialysis (ICMD) is an accepted method for monitoring changes in neurochemistry from acute brain injury. The goal of this pilot study was to determine the feasibility of using ICMD to examine the neuropharmacokinetics of temozolomide in brain interstitium following oral administration. Patients with primary or metastatic brain tumors had a microdialysis catheter placed in peritumoral brain tissue at the time of surgical debulking. Computerized tomography scan confirmed the catheter location. Patients received a single oral dose of temozolomide (150 mg/m2) on the first postoperative day, serial plasma and ICMD samples were collected over 24 hours, and temozolomide concentrations were determined by tandem mass spectrometry. Nine patients were enrolled. Dialysate and plasma samples were successfully collected from seven of the nine patients. The mean temozolomide areas under the concentration-time curve (AUC) in plasma and brain interstitium were 17.1 and 2.7 microg/mL x hour, with an average brain interstitium/plasma AUC ratio of 17.8%. The mean peak temozolomide concentration in the brain was 0.6 +/- 0.3 microg/mL, and the mean time to reach peak level in brain was 2.0 +/- 0.8 hours. The use of ICMD to measure the neuropharmacokinetics of systemically administered chemotherapy is safe and feasible. Concentrations of temozolomide in brain interstitium obtained by ICMD are consistent with published data obtained in a preclinical ICMD model, as well as from clinical studies of cerebrospinal fluid. However, the delayed time required to achieve maximum temozolomide concentrations in brain suggests that current chemoradiation regimens may be improved by administering temozolomide 2 to 3 hours before radiation.

Aspects on the Physiological and Biochemical Foundations of Neurocritical Care

PubMed Central

Nordström, Carl-Henrik; Koskinen, Lars-Owe; Olivecrona, Magnus

2017-01-01

Neurocritical care (NCC) is a branch of intensive care medicine characterized by specific physiological and biochemical monitoring techniques necessary for identifying cerebral adverse events and for evaluating specific therapies. Information is primarily obtained from physiological variables related to intracranial pressure (ICP) and cerebral blood flow (CBF) and from physiological and biochemical variables related to cerebral energy metabolism. Non-surgical therapies developed for treating increased ICP are based on knowledge regarding transport of water across the intact and injured blood–brain barrier (BBB) and the regulation of CBF. Brain volume is strictly controlled as the BBB permeability to crystalloids is very low restricting net transport of water across the capillary wall. Cerebral pressure autoregulation prevents changes in intracranial blood volume and intracapillary hydrostatic pressure at variations in arterial blood pressure. Information regarding cerebral oxidative metabolism is obtained from measurements of brain tissue oxygen tension (PbtO2) and biochemical data obtained from intracerebral microdialysis. As interstitial lactate/pyruvate (LP) ratio instantaneously reflects shifts in intracellular cytoplasmatic redox state, it is an important indicator of compromised cerebral oxidative metabolism. The combined information obtained from PbtO2, LP ratio, and the pattern of biochemical variables reveals whether impaired oxidative metabolism is due to insufficient perfusion (ischemia) or mitochondrial dysfunction. Intracerebral microdialysis and PbtO2 give information from a very small volume of tissue. Accordingly, clinical interpretation of the data must be based on information of the probe location in relation to focal brain damage. Attempts to evaluate global cerebral energy state from microdialysis of intraventricular fluid and from the LP ratio of the draining venous blood have recently been presented. To be of clinical relevance, the information from all monitoring techniques should be presented bedside online. Accordingly, in the future, the chemical variables obtained from microdialysis will probably be analyzed by biochemical sensors. PMID:28674514

In vivo brain microdialysis: advances in neuropsychopharmacology and drug discovery.

PubMed

Darvesh, Altaf S; Carroll, Richard T; Geldenhuys, Werner J; Gudelsky, Gary A; Klein, Jochen; Meshul, Charles K; Van der Schyf, Cornelis J

2011-02-01

INTRODUCTION: Microdialysis is an important in vivo sampling technique, useful in the assay of extracellular tissue fluid. The technique has both pre-clinical and clinical applications but is most widely used in neuroscience. The in vivo microdialysis technique allows measurement of neurotransmitters such as acetycholine (ACh), the biogenic amines including dopamine (DA), norepinephrine (NE) and serotonin (5-HT), amino acids such as glutamate (Glu) and gamma aminobutyric acid (GABA), as well as the metabolites of the aforementioned neurotransmitters, and neuropeptides in neuronal extracellular fluid in discrete brain regions of laboratory animals such as rodents and non-human primates. AREAS COVERED: In this review we present a brief overview of the principles and procedures related to in vivo microdialysis and detail the use of this technique in the pre-clinical measurement of drugs designed to be used in the treatment of chemical addiction, neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and as well as psychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD) and schizophrenia. This review offers insight into the tremendous utility and versatility of this technique in pursuing neuropharmacological investigations as well its significant potential in rational drug discovery. EXPERT OPINION: In vivo microdialysis is an extremely versatile technique, routinely used in the neuropharmacological investigation of drugs used for the treatment of neurological disorders. This technique has been a boon in the elucidation of the neurochemical profile and mechanism of action of several classes of drugs especially their effects on neurotransmitter systems. The exploitation and development of this technique for drug discovery in the near future will enable investigational new drug candidates to be rapidly moved into the clinical trial stages and to market thus providing new successful therapies for neurological diseases that are currently in demand.

An Update of the Classical and Novel Methods Used for Measuring Fast Neurotransmitters During Normal and Brain Altered Function

PubMed Central

Cifuentes Castro, Victor Hugo; López Valenzuela, Carmen Lucía; Salazar Sánchez, Juan Carlos; Peña, Kenia Pardo; López Pérez, Silvia J.; Ibarra, Jorge Ortega; Villagrán, Alberto Morales

2014-01-01

To understand better the cerebral functions, several methods have been developed to study the brain activity, they could be related with morphological, electrophysiological, molecular and neurochemical techniques. Monitoring neurotransmitter concentration is a key role to know better how the brain works during normal or pathological conditions, as well as for studying the changes in neurotransmitter concentration with the use of several drugs that could affect or reestablish the normal brain activity. Immediate response of the brain to environmental conditions is related with the release of the fast acting neurotransmission by glutamate (Glu), γ-aminobutyric acid (GABA) and acetylcholine (ACh) through the opening of ligand-operated ion channels. Neurotransmitter release is mainly determined by the classical microdialysis technique, this is generally coupled to high performance liquid chromatography (HPLC). Detection of neurotransmitters can be done by fluorescence, optical density, electrochemistry or other detection systems more sophisticated. Although the microdialysis method is the golden technique to monitor the brain neurotransmitters, it has a poor temporal resolution. Recently, with the use of biosensor the drawback of temporal resolution has been improved considerably, however other inconveniences have merged, such as stability, reproducibility and the lack of reliable biosensors mainly for GABA. The aim of this review is to show the important advances in the different ways to measure neurotransmitter concentrations; both with the use of classic techniques as well as with the novel methods and alternant approaches to improve the temporal resolution. PMID:25977677

Methods of measuring metabolism during surgery in humans: focus on the liver-brain relationship.

PubMed

Battezzati, Alberto; Bertoli, Simona

2004-09-01

The purpose of this work is to review recent advances in setting methods and models for measuring metabolism during surgery in humans. Surgery, especially solid organ transplantation, may offer unique experimental models in which it is ethically acceptable to gain information on difficult problems of amino acid and protein metabolism. Two areas are reviewed: the metabolic study of the anhepatic phase during liver transplantation and brain microdialysis during cerebral surgery. The first model offers an innovative approach to understand the relative role of liver and extrahepatic organs in gluconeogenesis, and to evaluate whether other organs can perform functions believed to be exclusively or almost exclusively performed by the liver. The second model offers an insight to intracerebral metabolism that is closely bound to that of the liver. The recent advances in metabolic research during surgery provide knowledge immediately useful for perioperative patient management and for a better control of surgical stress. The studies during the anhepatic phase of liver transplantation have showed that gluconeogenesis and glutamine metabolism are very active processes outside the liver. One of the critical organs for extrahepatic glutamine metabolism is the brain. Microdialysis studies helped to prove that in humans there is an intense trafficking of glutamine, glutamate and alanine among neurons and astrocytes. This delicate network is influenced by systemic amino acid metabolism. The metabolic dialogue between the liver and the brain is beginning to be understood in this light in order to explain the metabolic events of brain damage during liver failure.

Nonconvulsive electrographic seizures after traumatic brain injury result in a delayed, prolonged increase in intracranial pressure and metabolic crisis.

PubMed

Vespa, Paul M; Miller, Chad; McArthur, David; Eliseo, Mathew; Etchepare, Maria; Hirt, Daniel; Glenn, Thomas C; Martin, Neil; Hovda, David

2007-12-01

To determine whether nonconvulsive electrographic post-traumatic seizures result in increases in intracranial pressure and microdialysis lactate/pyruvate ratio. Prospective monitoring with retrospective data analysis. Single center academic neurologic intensive care unit. Twenty moderate to severe traumatic brain injury patients (Glasgow Coma Score 3-13). Continuous electroencephalography and cerebral microdialysis were performed for 7 days after injury. Ten patients had seizures and were compared with a matched cohort of traumatic brain injury patients without seizures. The seizures were repetitive and constituted status epilepticus in seven of ten patients. Using a within-subject design, post-traumatic seizures resulted in episodic increases in intracranial pressure (22.4 +/- 7 vs. 12.8 +/- 4.3 mm Hg; p < .001) and an episodic increase in lactate/pyruvate ratio (49.4 +/- 16 vs. 23.8 +/- 7.6; p < .001) in the seizure group. Using a between-subjects comparison, the seizure group demonstrated a higher mean intracranial pressure (17.6 +/- 6.5 vs. 12.2 +/- 4.2 mm Hg; p < .001), a higher mean lactate/pyruvate ratio (38.6 +/- 18 vs. 27 +/- 9; p < .001) compared with nonseizure patients. The intracranial pressure and lactate/pyruvate ratio remained elevated beyond postinjury hour 100 in the seizure group but not the nonseizure group (p < .02). Post-traumatic seizures result in episodic as well as long-lasting increases in intracranial pressure and microdialysis lactate/pyruvate ratio. These data suggest that post-traumatic seizures represent a therapeutic target for patients with traumatic brain injury.

THE NEUROPHARMACOKINETICS OF TEMOZOLOMIDE IN PATIENTS WITH RESECTABLE BRAIN TUMORS: POTENTIAL IMPLICATIONS FOR THE CURRENT APPROACH TO CHEMORADIATION

PubMed Central

Portnow, Jana; Badie, Behnam; Chen, Mike; Liu, An; Blanchard, Suzette; Synold, Timothy W.

2010-01-01

Purpose Intracerebral microdialysis (ICMD) is an accepted methodology for monitoring changes in neurochemistry from acute brain injury. The goal of this pilot study was to determine the feasibility of using ICMD to examine the neuropharmacokinetics (nPK) of temozolomide (TMZ) in brain interstitium (BI) following oral administration. Experimental Design Patients with primary or metastatic brain tumors had a microdialysis catheter placed in peritumoral brain tissue at the time of surgical debulking. CT scan confirmed the catheter location. Patients received a single oral dose of TMZ (150 mg/m2) on the first post-operative day, serial plasma and ICMD samples were collected over 24 hrs, and TMZ concentrations were determined by tandem mass spectrometry. Results Nine patients were enrolled. Dialysate and plasma samples were successfully collected from 7 of the 9 patients. The mean TMZ area-under-the-concentration-time-curve (AUC) in plasma and BI were 17.1 and 2.7 μg/ml × hr, with an average BI/plasma AUC ratio of 17.8%. The mean peak TMZ concentration in brain was 0.6 ± 0.3 μg/ml, and the mean time to reach peak level in brain was 2.0 ± 0.8 hrs. Conclusions The use of ICMD to measure the nPK of systemically administered chemotherapy is safe and feasible. Concentrations of TMZ in BI obtained by ICMD are consistent with published data obtained in a pre-clinical ICMD model, as well as from clinical studies of cerebrospinal fluid. However, the delayed time required to achieve maximum TMZ concentrations in brain suggests that current chemoradiation regimens may be improved by administering TMZ 2-3 hours before radiation. PMID:19861433

Microdialysis Monitoring in Clinical Traumatic Brain Injury and Its Role in Neuroprotective Drug Development.

PubMed

Thelin, Eric Peter; Carpenter, Keri L H; Hutchinson, Peter J; Helmy, Adel

2017-03-01

Injuries to the central nervous system continue to be vast contributors to morbidity and mortality; specifically, traumatic brain injury (TBI) is the most common cause of death during the first four decades of life. Several modalities are used to monitor patients suffering from TBI in order to prevent detrimental secondary injuries. The microdialysis (MD) technique, introduced during the 1990s, presents the treating physician with a robust monitoring tool for brain chemistry in addition to conventional intracranial pressure monitoring. Nevertheless, some limitations remain, such as limited spatial resolution. Moreover, while there have been several attempts to develop new potential pharmacological therapies in TBI, there are currently no available drugs which have shown clinical efficacy that targets the underlying pathophysiology, despite various trials investigating a plethora of pharmaceuticals. Specifically in the brain, MD is able to demonstrate penetration of the drug through the blood-brain barrier into the brain extracellular space at potential site of action. In addition, the downstream effects of drug action can be monitored directly. In the future, clinical MD, together with other monitoring modalities, can identify specific pathological substrates which require tailored treatment strategies for patients suffering from TBI.

Intracerebral microdialysis coupled to LC-MS/MS for the determination tramadol and its major pharmacologically active metabolite O-desmethyltramadol in rat brain microdialysates.

PubMed

Liu, Mingzhou; Wang, Peng; Yu, Xuming; Dong, Guicheng; Yue, Jiang

2017-08-01

A rapid and sensitive method involving liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS) coupled to an intracerebral microdialysis technique was developed for the determination and pharmacokinetic investigation of tramadol and its major active metabolite O-desmethyltramadol (ODT) in rat brain. The microdialysis samples were separated on a C18 column and eluted with a mobile phase of acetonitrile-water-formic acid (50:50:0.1; v/v/v) at a flow rate of 0.3 mL/min. The ESI-MS/MS spectra were performed in electrospray positive ion mode, and the analytes were detected by multiple reaction monitoring (MRM) of the transitions m/z [M + H] + 264.3 → 58.2 for tramadol, m/z [M + H] + 250.3 → 58.3 for ODT, and m/z [M + H] + 379.4 → 264.0 for ambroxol (internal standard; IS). The total run time was 4.0 min. A lower limit of quantitation (LLOQ) was achieved as 1 ng/mL for tramadol and 0.5 ng/mL for ODT, with excellent linearity over a concentration range of 1 ~ 500 ng/mL (r > 0.99) for tramadol and 0.5 ~ 50 ng/mL for ODT (r > 0.99), respectively. The proposed method was successfully applied to the pharmacokinetic studies of tramadol and ODT in rat brain. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

P-glycoprotein and multidrug resistance-associated protein are involved in the regulation of extracellular levels of the major antiepileptic drug carbamazepine in the brain.

PubMed

Potschka, H; Fedrowitz, M; Löscher, W

2001-11-16

Despite considerable advances in the pharmacotherapy of epilepsy, about 30% of epileptic patients are refractory to antiepileptic drugs (AEDs). In most cases, a patient who is resistant to one major AED is also refractory to other AEDs, although these drugs act by different mechanisms. The mechanisms that lead to drug resistance in epilepsy are not known. Recently, over-expression of multidrug transporters, such as P-glycoprotein (PGP) and multidrug resistance-associated protein (MRP), has been reported in surgically resected epileptogenic human brain tissue and suggested to contribute to the drug resistance of epilepsy. However, it is not known to what extent multidrug transporters such as PGP or MRP are involved in transport of AEDs. In the present study, we used in vivo microdialysis in rats to study whether the concentration of carbamazepine in the extracellular fluid of the cerebral cortex can be enhanced by inhibition of PGP or MRP, using the PGP inhibitor verapamil and the MRP inhibitor probenecid. Local perfusion with verapamil or probenecid via the microdialysis probe increased the extracellular concentration of carbamazepine. The data indicate that both PGP and MRP participate in the regulation of extracellular brain concentrations of the major AED carbamazepine.

Changes in Extracellular Striatal Acetylcholine and Brain Seizure Activity Following Acute Exposure to Nerve Against in Freely Moving Guinea Pigs

DTIC Science & Technology

2010-01-01

Literature 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Changes in extracellular striatal acetylcholine and brain seizure activity following...Acetylcholine, acetylcholinesterase, choline, guinea pig, in vivo microdialysis, nerve agents, organophosphorus compounds, sarin, seizure activity ...RESEARCH ARTICLE Changes in extracellular striatal acetylcholine and brain seizure activity following acute exposure to nerve agents in freely

Stimulus-dependent changes of extracellular glucose in the rat hippocampus determined by in vivo microdialysis.

PubMed

Rex, A; Bert, B; Fink, H; Voigt, J-P

2009-10-19

Neuronal activity is tightly coupled with brain energy metabolism; and glucose is an important energy substrate for neurons. The present in vivo microdialysis study was aimed at investigating changes in extracellular glucose concentrations in the rat ventral hippocampus due to exposure to the elevated plus maze. Determination of basal hippocampal glucose and lactate/pyruvate ratio in male Wistar rats was conducted in the home cage using in vivo microdialysis. Rats were exposed to the elevated plus maze, a rodent model of anxiety-related behaviour, or to unspecific stress induced by white noise (95dB) as a control condition. Basal hippocampal levels of glucose, as determined by zero-net-flux, and the basal lactate/pyruvate ratio were 1.49+/-0.05mmol/l and 13.8+/-1.1, respectively. In rats without manipulation, glucose levels remained constant throughout the experiment (120min). By contrast, exposure to the elevated plus maze led to a temporary decline in hippocampal glucose (-33.2+/-4.4%) which returned to baseline level in the home cage. White noise caused only a non-significant decrease in extracellular glucose level (-9.3+/-3.5%). In all groups, the lactate/pyruvate ratio remained unchanged by the experimental procedures. Our microdialysis study demonstrates that exposure to the elevated plus maze induces a transient decrease in extracellular hippocampal glucose concentration. In contrast, an unspecific stimulus did not change hippocampal glucose. The latter suggests that only specific behavioural stimuli increase hippocampal glucose utilization in the ventral hippocampus.

Image-guided intracranial cannula placement for awake in vivo microdialysis in nonhuman primates

NASA Astrophysics Data System (ADS)

Chen, Antong; Bone, Ashleigh; Hines, Catherine D. G.; Dogdas, Belma; Montgomery, Tamara O.; Michener, Maria; Winkelmann, Christopher T.; Ghafurian, Soheil; Lubbers, Laura S.; Renger, John; Bagchi, Ansuman; Uslaner, Jason M.; Johnson, Colena; Zariwala, Hatim A.

2016-03-01

Intracranial microdialysis is used for sampling neurochemicals and large peptides along with their metabolites from the interstitial fluid (ISF) of the brain. The ability to perform this in nonhuman primates (NHP) e.g., rhesus could improve the prediction of pharmacokinetic (PK) and pharmacodynamics (PD) action of drugs in human. However, microdialysis in rhesus brains is not as routinely performed as in rodents. One challenge is that the precise intracranial probe placement in NHP brains is difficult due to the richness of the anatomical structure and the variability of the size and shape of brains across animals. Also, a repeatable and reproducible ISF sampling from the same animal is highly desirable when combined with cognitive behaviors or other longitudinal study end points. Toward that end, we have developed a semi-automatic flexible neurosurgical method employing MR and CT imaging to (a) derive coordinates for permanent guide cannula placement in mid-brain structures and (b) fabricate a customized recording chamber to implant above the skull for enclosing and safeguarding access to the cannula for repeated experiments. In order to place the intracranial guide cannula in each subject, the entry points in the skull and the depth in the brain were derived using co-registered images acquired from MR and CT scans. The anterior/posterior (A/P) and medial-lateral (M/L) rotation in the pose of the animal was corrected in the 3D image to appropriately represent the pose used in the stereotactic frame. An array of implanted fiducial markers was used to transform stereotactic coordinates to the images. The recording chamber was custom fabricated using computer-aided design (CAD), such that it would fit the contours of the individual skull with minimum error. The chamber also helped in guiding the cannula through the entry points down a trajectory into the depth of the brain. We have validated our method in four animals and our results indicate average placement error of cannula to be 1.20 +/- 0.68 mm of the targeted positions. The approach employed here for derivation of the coordinates, surgical implantation and post implant validation is built using traditional access to surgical and imaging methods without the necessity of intra-operative imaging. The validation of our method lends support to its wider application in most nonhuman primate laboratories with onsite MR and CT imaging capabilities.

Sex differences in abuse-related neurochemical and behavioral effects of 3,4-methylenedioxymethamphetamine (MDMA) in rats.

PubMed

Lazenka, M F; Suyama, J A; Bauer, C T; Banks, M L; Negus, S S

2017-01-01

3,4-Methylenedioxymethamphetamine (MDMA) is a substrate for dopamine (DA), norepinephrine and serotonin (5HT) transporters that produces greater pharmacological effects on certain endpoints in females than males in both clinical and rodent preclinical studies. To evaluate potential for sex differences in abuse-related MDMA effects, the present study compared MDMA effects on intracranial self-stimulation (ICSS) and on in vivo microdialysis measurements of DA or 5HT in the nucleus accumbens (NAc) in female and male Sprague-Dawley rats. For ICSS studies, electrodes were implanted in the medial forebrain bundle and rats trained to press for electrical stimulation over a range of frequencies (56-158Hz, 0.05 log increments) under a fixed-ratio 1 schedule, and the potency (0.32-3.2mg/kg, 10min pretreatment) and time course (3.2. mg/kg, 10-180min pretreatment) of MDMA effects were determined. For in vivo microdialysis, rats were implanted with bilateral guide cannulae targeting the NAc, and the time course of MDMA effects (1.0-3.2mg/kg, 0-180min) on DA and 5HT was determined. MDMA produced qualitatively similar effects in both sexes on ICSS (both increases in low ICSS rates maintained by low brain-stimulation frequencies and decreases in high ICSS rates maintained by high brain-stimulation frequencies) and microdialysis (increases in both DA and 5HT). The duration and peak levels of both abuse-related ICSS facilitation and increases in NAc DA were longer in females. MDMA was also more potent to increase 5HT in females. These results provide evidence for heightened sensitivity of females to abuse-related behavioral and neurochemical effects of MDMA in rats. Copyright © 2016 Elsevier Inc. All rights reserved.

Sex Differences in Abuse-Related Neurochemical and Behavioral Effects of 3,4-methylenedioxymethamphetamine (MDMA) in Rats

PubMed Central

Lazenka, MF; Suyama, JA; Bauer, CT; Banks, ML; Negus, SS

2016-01-01

3,4-methylenedioxymethamphetamine (MDMA) is a substrate for the dopamine (DA), norepinephrine and serotonin (5HT) transporters that produces greater pharmacological effects on certain endpoints in females than males in both clinical and rodent preclinical studies. To evaluate potential for sex differences in abuse-related MDMA effects, the present study compared MDMA effects on intracranial self-stimulation (ICSS) and on in vivo microdialysis measurements of DA or 5HT in the nucleus accumbens (NAc) in female and male Sprague-Dawley rats. For ICSS studies, electrodes were implanted in the medial forebrain bundle and rats trained to press for electrical stimulation over a range of frequencies (56–158 Hz, 0.05 log increments) under a fixed-ratio 1 schedule, and the potency (0.32–3.2 mg/kg, 10 min pretreatment) and time course (3.2. mg/kg, 10–180 min pretreatment) of MDMA effects were determined. For in vivo microdialysis, rats were implanted with bilateral guide cannulae targeting the NAc, and the time course of MDMA effects (1.0–3.2 mg/kg, 0–180 min) on DA and 5HT was determined. MDMA produced qualitatively similar effects in both sexes on ICSS (both increases in low ICSS rates maintained by low brain-stimulation frequencies and decreases in high ICSS rates maintained by high brain-stimulation frequencies) and microdialysis (increases in both DA and 5HT). The duration and peak levels of both abuse-related ICSS facilitation and increases in NAc DA were longer in females. MDMA was also more potent to increase 5HT in females. These results provide evidence for heightened sensitivity of females to abuse-related behavioral and neurochemical effects of MDMA in rats. PMID:27566288

Effects of sarizotan in animal models of ADHD: challenging pharmacokinetic-pharmacodynamic relationships.

PubMed

Danysz, Wojciech; Flik, Gunnar; McCreary, Andrew; Tober, Carsten; Dimpfel, Wilfried; Bizot, Jean C; Kostrzewa, Richard; Brown, Russell W; Jatzke, Claudia C; Greco, Sergio; Jenssen, Ann-Kristin; Parsons, Christopher G

2015-09-01

Sarizotan 1-[(2R)-3,4-dihydro-2H-chromen-2-yl]-N-[[5-(4-fluorophenyl) pyridin-3-yl]methyl] methenamine, showed an in vivo pharmaco-EEG profile resembling that of methylphenidate which is used in attention deficit/hyperactivity disorder (ADHD). In turn, we tested sarizotan against impulsivity in juvenile rats measuring the choice for large delayed vs. a small immediate reward in a T-maze and obtained encouraging results starting at 0.03 mg/kg (plasma levels of ~11 nM). Results from rats treated neonatally with 6-hydroxydopamine (6-OHDA), also supported anti-ADHD activity although starting at 0.3 mg/kg. However, microdialysis studies revealed that free brain concentration of sarizotan at active doses were below its affinity for 5-HT1A receptors, the assumed primary target. In contrast, electrophysiological experiments in mid-brain Raphé serotonergic cells paralleled by plasma sampling showed that there was ~60% inhibition of firing rate—indicating significant activation of 5-HT1A receptors—at a plasma concentration of 76 nM. In line with this, we observed that sarizotan concentrations in brain homogenates were similar to total blood levels but over 500 fold higher than free extracellular fluid (ECF) concentrations as measured using brain microdialysis. These data suggest that sarizotan may have potential anti-ADHD effects at low doses free of the previously reported side-effects. Moreover, in this case a classical pharmacokinetic-pharmacodynamic relationship based on free brain concentrations seems to be less appropriate than target engagement pharmacodynamic readouts.

Brain microdialysis as a tool to explore the ionic profile of the brain extracellular space in neurocritical patients: a methodological approach and feasibility study.

PubMed

Martínez-Valverde, Tamara; Vidal-Jorge, Marian; Montoya, Noelia; Sánchez-Guerrero, Angela; Manrique, Susana; Munar, Francisca; Pellegri, Maria-Dolors; Poca, Maria-Antonia; Sahuquillo, Juan

2015-01-01

Our aim is to determine whether the ionic concentration in brain microdialysate enables calculations of the actual Na(+), K(+), and Cl(-) concentrations in vitro and whether this method can be applied to determine the ionic concentrations in the brain extracellular fluid. We designed an experiment using CMA-71 probes (M Dialysis, Stockholm, Sweden) and the standard conditions used in a clinical setting. Nine CMA-71 probes were inserted in different matrices and perfused with mock cerebrospinal fluid containing 3% albumin at the standard infusion rate used in the clinical setting (0.3 μL/min). Microvials were replaced every 12 h, and the ionic concentrations, both in the dialysate and the matrix, were analyzed. For each ion, scatter plots were built, with [Na(+)], [K(+)], and [Cl(-)] in the dialysate as the predictor variables and the matrix concentrations as the outcome variables. A linear regression model allowed us to calculate the true ionic concentrations in the matrix. To demonstrate the feasibility of the method, we present the calculated ionic profile of one patient with a malignant infarction and a second with a severe traumatic brain injury. Our results confirm that the ionic concentration in microdialysate can be used to calculate the true concentrations of ions in a matrix and the actual concentrations in the extracellular fluid. Microdialysis offers the unique possibility of monitoring the dynamic changes of ions in the brain over time and opens a new avenue to explore the brain's ionic profile, its changes in brain edema, and how this profile can be modified with different therapies.

A microdialysis study of the novel antiepileptic drug levetiracetam: extracellular pharmacokinetics and effect on taurine in rat brain

PubMed Central

Tong, X; Patsalos, P N

2001-01-01

Using a rat model which allows serial blood sampling and concurrent brain microdialysis sampling, we have investigated the temporal kinetic inter-relationship of levetiracetam in serum and brain extracellular fluid (frontal cortex and hippocampus) following systemic administration of levetiracetam, a new antiepileptic drug. Concurrent extracellular amino acid concentrations were also determined. After administration (40 or 80 mg kg−1), levetiracetam rapidly appeared in both serum (Tmax, 0.4 – 0.7 h) and extracellular fluid (Tmax, 2.0 – 2.5 h) and concentrations rose linearly and dose-dependently, suggesting that transport across the blood-brain barrier is rapid and not rate-limiting. The serum free fraction (free/total serum concentration ratio; mean±s.e.mean range 0.93 – 1.05) was independent of concentration and confirms that levetiracetam is not bound to blood proteins. The kinetic profiles for the hippocampus and frontal cortex were indistinguishable suggesting that levetiracetam distribution in the brain is not brain region specific. However, t1/2 values were significantly larger than those for serum (mean range, 3.0 – 3.3 h vs 2.1 – 2.3 h) and concentrations did not attain equilibrium with respect to serum. Levetiracetam (80 mg kg−1) was associated with a significant reduction in taurine in the hippocampus and frontal cortex. Other amino acids were unaffected by levetiracetam. Levetiracetam readily and rapidly enters the brain without regional specificity. Its prolonged efflux from and slow equilibration within the brain may explain, in part, its long duration of action. The concurrent changes in taurine may contribute to its mechanism of action. PMID:11454660

A high-accuracy measurement method of glucose concentration in interstitial fluid based on microdialysis

NASA Astrophysics Data System (ADS)

Li, Dachao; Xu, Qingmei; Liu, Yu; Wang, Ridong; Xu, Kexin; Yu, Haixia

2017-11-01

A high-accuracy microdialysis method that can provide the reference values of glucose concentration in interstitial fluid for the accurate evaluation of non-invasive and minimally invasive continuous glucose monitoring is reported in this study. The parameters of the microdialysis process were firstly optimized by testing and analyzing three main factors that impact microdialysis recovery, including the perfusion rate, temperature, and glucose concentration in the area surrounding the microdialysis probe. The precision of the optimized microdialysis method was then determined in a simulation system that was designed and established in this study to simulate variations in continuous glucose concentration in the human body. Finally, the microdialysis method was tested for in vivo interstitial glucose concentration measurement.

First plasma and tissue pharmacokinetic study of the YSNSG cyclopeptide, a new integrin antagonist, using microdialysis.

PubMed

Slimano, Florian; Djerada, Zoubir; Bouchene, Salim; Van Gulick, Laurence; Brassart-Pasco, Sylvie; Dukic, Sylvain

2017-07-15

The YSNSG peptide is a synthetic peptide targeting α v β 3 integrin. This peptide exhibits promising activity in vitro and in vivo against melanoma. To determine pharmacokinetic parameters and predictive active doses in the central nervous system (CNS) and subcutaneous tissue (SC), we conducted microdialysis coupled with pharmacokinetic modeling and Monte Carlo simulation. After a recovery period of surgical procedures, a microdialysis probe was inserted in the caudate and in subcutaneous tissue. Plasma samples and dialysates collected 5h after YSNSG intravenous administration (10mg/kg) were analyzed by UPLC-MS/MS. A nonlinear mixed-effect modeling approach implemented in Monolix® 2016R1 was performed. Model selection and evaluation were based on the usual diagnostic plot, precision and information criteria. The primary plasma and tissue pharmacokinetic parameters were comparable with those of other integrin antagonists, such as cilengitide or ATN-161. Tissue/plasma and brain/plasma area under the curve (AUC) ratio were 66.2±21.6% and 3.6±4.7%, respectively. Two models of 2-compartments with an additional microdialysis compartment, parameterized as rate constants (k for elimination, k12/k21 and k13/k31 for distribution) and volumes (central V1 and peripheral microdialysis compartment V3) with zero-order input were selected to describe the dialysate concentrations in CNS and SC. The inter-individual variability (IIV) was described by exponential terms, and residual variability was described by a combined additive and proportional error model. Individual AUC (plasma and tissues) values were derived for each animal using the Empirical-Bayes-Estimates of the individual parameters. The regimens needed to achieve an in vitro predetermined target concentration in tissues were studied by Monte Carlo simulations using Monolix® 2016R1. YSNSG pharmacokinetic parameters show promising results in terms of subcutaneous disposition. Further investigations into such processes as encapsulation and intratumoral disposition are currently being conducted. Copyright © 2017 Elsevier B.V. All rights reserved.

New Insights on Different Response of MDMA-Elicited Serotonin Syndrome to Systemic and Intracranial Administrations in the Rat Brain

PubMed Central

Shokry, Ibrahim M.; Callanan, John J.; Sousa, John; Tao, Rui

2016-01-01

In spite of the fact that systemic administration of MDMA elicits serotonin syndrome, direct intracranial administration fails to reproduce the effect. To reconcile these findings, it has been suggested that the cause of serotonin syndrome is attributed mainly to MDMA hepatic metabolites, and less likely to MDMA itself. Recently, however, this explanation has been challenged, and alternative hypotheses need to be explored. Here, we tested the hypothesis that serotonin syndrome is the result of excessive 5HT simultaneously in many brain areas, while MDMA administered intracranially fails to cause serotonin syndrome because it produces only a localized effect at the delivery site and not to other parts of the brain. This hypothesis was examined using adult male Sprague Dawley rats by comparing 5HT responses in the right and left hemispheric frontal cortices, right and left hemispheric diencephalons, and medullar raphe nucleus. Occurrence of serotonin syndrome was confirmed by measuring change in body temperature. Administration routes included intraperitoneal (IP), intracerebroventricular (ICV) and reverse microdialysis. First, we found that IP administration caused excessive 5HT in all five sites investigated and induced hypothermia, suggesting the development of the serotonin syndrome. In contrast, ICV and reverse microdialysis caused excessive 5HT only in regions of delivery sites without changes in body-core temperature, suggesting the absence of the syndrome. Next, chemical dyes were used to trace differences in distribution and diffusion patterns between administration routes. After systemic administration, the dyes were found to be evenly distributed in the brain. However, the dyes administered through ICV or reverse microdialysis injection still remained in the delivery sites, poorly diffusing to the brain. In conclusion, intracranial MDMA administration in one area has no or little effect on other areas, which must be considered a plausible reason for the difference in MDMA-elicited serotonin syndrome between systemic and intracranial administrations. PMID:27192423

New Insights on Different Response of MDMA-Elicited Serotonin Syndrome to Systemic and Intracranial Administrations in the Rat Brain.

PubMed

Shokry, Ibrahim M; Callanan, John J; Sousa, John; Tao, Rui

2016-01-01

In spite of the fact that systemic administration of MDMA elicits serotonin syndrome, direct intracranial administration fails to reproduce the effect. To reconcile these findings, it has been suggested that the cause of serotonin syndrome is attributed mainly to MDMA hepatic metabolites, and less likely to MDMA itself. Recently, however, this explanation has been challenged, and alternative hypotheses need to be explored. Here, we tested the hypothesis that serotonin syndrome is the result of excessive 5HT simultaneously in many brain areas, while MDMA administered intracranially fails to cause serotonin syndrome because it produces only a localized effect at the delivery site and not to other parts of the brain. This hypothesis was examined using adult male Sprague Dawley rats by comparing 5HT responses in the right and left hemispheric frontal cortices, right and left hemispheric diencephalons, and medullar raphe nucleus. Occurrence of serotonin syndrome was confirmed by measuring change in body temperature. Administration routes included intraperitoneal (IP), intracerebroventricular (ICV) and reverse microdialysis. First, we found that IP administration caused excessive 5HT in all five sites investigated and induced hypothermia, suggesting the development of the serotonin syndrome. In contrast, ICV and reverse microdialysis caused excessive 5HT only in regions of delivery sites without changes in body-core temperature, suggesting the absence of the syndrome. Next, chemical dyes were used to trace differences in distribution and diffusion patterns between administration routes. After systemic administration, the dyes were found to be evenly distributed in the brain. However, the dyes administered through ICV or reverse microdialysis injection still remained in the delivery sites, poorly diffusing to the brain. In conclusion, intracranial MDMA administration in one area has no or little effect on other areas, which must be considered a plausible reason for the difference in MDMA-elicited serotonin syndrome between systemic and intracranial administrations.

Herb-Drug Pharmacokinetic Interaction of a Traditional Chinese Medicine Jia-Wei-Xiao-Yao-San with 5-Fluorouracil in the Blood and Brain of Rat Using Microdialysis

PubMed Central

Chiang, Meng-Hsuan; Chang, Li-Wen; Wang, Ju-Wen; Lin, Lie-Chwen; Tsai, Tung-Hu

2015-01-01

According to a survey from the National Health Insurance Research Database (NHIRD), Jia-Wei-Xiao-Yao-San (JWXYS) is the most popular Chinese medicine for cancer patients in Taiwan. 5-Fluorouracil (5-FU) is a general anticancer drug for the chemotherapy. To investigate the herb-drug interaction of JWXYS on pharmacokinetics of 5-FU, a microdialysis technique coupled with a high-performance liquid chromatography system was used to monitor 5-FU in rat blood and brain. Rats were divided into four parallel groups, one of which was treated with 5-FU (100 mg/kg, i.v.) alone and the remaining three groups were pretreated with a different dose of JWXYS (600, 1200, or 2400 mg/kg/day for 5 consecutive days) followed by a combination with 5-FU. This study demonstrates that 5-FU with JWXYS (600 mg/kg/day or 1200 mg/kg/day) has no significant effect on the pharmacokinetics of 5-FU in the blood and brain. However, JWXYS (2400 mg/kg/day) coadministered with 5-FU extends the elimination half-life and increases the volume of distribution of 5-FU in the blood. The elimination half-life of 5-FU in the brain for the pretreatment group with 2400 mg/kg/day of JWXYS is significantly longer than that for the group treated with 5-FU alone and also reduces the clearance. This study provides practical dosage information for clinical practice and proves the safety of 5-FU coadministered with JWXYS. PMID:25861367

Herb-drug pharmacokinetic interaction of a traditional chinese medicine jia-wei-xiao-yao-san with 5-Fluorouracil in the blood and brain of rat using microdialysis.

PubMed

Chiang, Meng-Hsuan; Chang, Li-Wen; Wang, Ju-Wen; Lin, Lie-Chwen; Tsai, Tung-Hu

2015-01-01

According to a survey from the National Health Insurance Research Database (NHIRD), Jia-Wei-Xiao-Yao-San (JWXYS) is the most popular Chinese medicine for cancer patients in Taiwan. 5-Fluorouracil (5-FU) is a general anticancer drug for the chemotherapy. To investigate the herb-drug interaction of JWXYS on pharmacokinetics of 5-FU, a microdialysis technique coupled with a high-performance liquid chromatography system was used to monitor 5-FU in rat blood and brain. Rats were divided into four parallel groups, one of which was treated with 5-FU (100 mg/kg, i.v.) alone and the remaining three groups were pretreated with a different dose of JWXYS (600, 1200, or 2400 mg/kg/day for 5 consecutive days) followed by a combination with 5-FU. This study demonstrates that 5-FU with JWXYS (600 mg/kg/day or 1200 mg/kg/day) has no significant effect on the pharmacokinetics of 5-FU in the blood and brain. However, JWXYS (2400 mg/kg/day) coadministered with 5-FU extends the elimination half-life and increases the volume of distribution of 5-FU in the blood. The elimination half-life of 5-FU in the brain for the pretreatment group with 2400 mg/kg/day of JWXYS is significantly longer than that for the group treated with 5-FU alone and also reduces the clearance. This study provides practical dosage information for clinical practice and proves the safety of 5-FU coadministered with JWXYS.

Microdialysis combined with RRLC-MS/MS for the pharmacokinetics of two major alkaloids of Bi qi capsule and the potential roles of P-gp and BCRP on their penetration.

PubMed

Ren, Tiankun; Li, Menglin; Zheng, Hao; Liu, Wenwei; Zhang, Jinlan

2018-05-31

Bi qi capsule (BQC) is a traditional Chinese medicine prescription that is clinically used for the treatment of rheumatoid arthritis. Strychnine and brucine, as two typical kinds of alkaloids, are the primary active and neurotoxic constituents of BQC. In this study, a sensitive and reliable rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) quantitative method was used to determine the concentrations of brucine and strychnine in rat brain and blood dialysates. The blood-brain barrier (BBB) penetration of free brucine and strychnine and their pharmacokinetic characteristics were investigated by the validated RRLC-MS/MS method coupled with in vivo microdialysis for the first time. The dialysate brain-blood AUC ratios of brucine were 0.098, 0.44 and 0.40 respectively at 0.4, 0.8 and 1.6 g kg -1 doses of BQC, and the dialysate brain-blood AUC ratios of strychnine were 0.20, 1.25 and 2.06 respectively at 0.4, 0.8 and 1.6 g kg -1 doses of BQC. The high brain-blood AUC ratios of brucine and strychnine were observed in medium and high dose groups of BQC. In addition, the effects of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) on brucine and strychnine across BBB were also studied using the above method as well as molecular docking. The results prompted that brucine was the substrate of P-gp, and strychnine might be the inhibitor of P-gp. Brucine and strychnine showed high brain penetration, so it is very important to well control the clinic dosage of BQC and manufactory quality for avoiding the side effects and obtaining good therapeutic efficacy. Our study could be further used in investigating BBB penetration for other drugs caused neurotoxicity. Copyright © 2018 Elsevier B.V. All rights reserved.

Novel L-Dopa and dopamine prodrugs containing a 2-phenyl-imidazopyridine moiety.

PubMed

Denora, Nunzio; Laquintana, Valentino; Lopedota, Angela; Serra, Mariangela; Dazzi, Laura; Biggio, Giovanni; Pal, Dhananjay; Mitra, Ashim K; Latrofa, Andrea; Trapani, Giuseppe; Liso, Gaetano

2007-07-01

The aim of this study was to gain insight into the feasibility of enhancing the delivery of L-Dopa and dopamine to the brain by linking these neurotransmitters and L-Dopa ethyl ester to 2-phenyl-3-carboxymethyl-imidazopyridine compounds giving rise to the so-called Dopimid compounds. A number of Dopimid compounds were synthesized and both stability and binding studies to dopaminergic and benzodiazepine receptors were performed. To evaluate whether Dopimid compounds are P-gp substrates, [(3)H]ritonavir uptake experiments and bi-directional transport studies on confluent MDCKII-MDR1 monolayers were carried out. The brain penetration properties of Dopimid compounds were estimated by the Clark's computational model and evaluated by investigation of their transport across BBMECs monolayers. The dopamine levels following the intraperitoneal administration of the selected Dopimid compounds were measured in vivo by using brain microdialysis in rat. Tested compounds were adequately stable in solution buffered at pH 7.4 but undergo faster cleavage in dilute rat serum at 37 degrees C. Receptor binding studies showed that Dopimid compounds are essentially devoid of affinity for dopaminergic and benzodiazepine receptors. [(3)H]ritonavir uptake experiments indicated that selected Dopimid compounds, like L-Dopa and dopamine hydrochloride, are not substrates of P-gp and it was also confirmed by bi-directional transport experiments across MDCKII-MDR1 monolayers. By Clark's model a significant brain penetration was deduced for L-Dopa ethyl ester and dopamine derivatives. Transport studies involving BBMECs monolayers indicated that some of these compounds should be able to cross the BBB. Interestingly, the rank order of apparent permeability (P (app)) values observed in these assays parallels that calculated by the computational approach. Brain microdialysis experiments in rat showed that intraperitoneal acute administration of some Dopimid compounds induced a dose-dependent increase in cortical dopamine output. Based on these results, it may be concluded that some Dopimid compounds can be proposed as novel L-Dopa and dopamine prodrugs.

[Analysis on microdialysis probe recovery of baicalin in vitro and in vivo based on LC-MS/MS].

PubMed

Chen, Teng-Fei; Liu, Jian-Xun; Zhang, Ying; Lin, Li; Song, Wen-Ting; Yao, Ming-Jiang

2017-06-01

To further study the brain behavior and the pharmacokinetics of baicalin in intercellular fluid of brain, and study the recovery rate and stability of brain and blood microdialysis probe of baicalin in vitro and in vivo. The concentration of baicalin in brain and blood microdialysates was determined by LC-MS/MS and the probe recovery for baicalin was calculated. The effects of different flow rates (0.50, 1.0, 1.5, 2.0，3.0 μL•min⁻¹) on recovery in vitro were determined by incremental method and decrement method. The effects of different drug concentrations (50.00, 200.0, 500.0, 1 000 μg•L⁻¹) and using times (0, 1, 2) on recovery in vitro were determined by incremental method. The probe recovery stability and effect of flow rate on recovery in vivo were determined by decrement method, and its results were compared with those in in vitro trial. The in vitro recovery of brain and blood probe of baicalin was decreased with the increase of flow rate under the same concentration; and at the same flow rate, different concentrations of baicalin had little influence on the recovery. The probe which had been used for 2 times showed no obvious change in probe recovery by syringe with 2% heparin sodium and ultrapure water successively. In vitro recovery rates obtained by incremental method and decrement method were approximately equal under the same condition, and the in vivo recovery determined by decrement method was similar with the in vitro results and they were showed a good stability within 10 h. The results showed that decrement method can be used for pharmacokinetic study of baicalin, and can be used to study probe recovery in vivo at the same time. Copyright© by the Chinese Pharmaceutical Association.

LC–MS/MS determination of carbamathione in microdialysis samples from rat brain and plasma

PubMed Central

Kaul, Swetha; Williams, Todd D.; Lunte, Craig E.; Faiman, Morris D.

2009-01-01

A selective liquid chromatography–tandem mass spectrometric (LC–MS/MS) method was developed for the determination of S-(N, N-diethylcarbamoyl) glutathione (carbamathione) in microdialysis samples from rat brain and plasma. S-(N, N-Diethylcarbamoyl) glutathione (carbamathione) is a metabolite of disulfiram. This metabolite may be responsible for disulfiram’s effectiveness in the treatment of cocaine dependence. An analytical method using liquid chromatography–tandem mass spectrometric (LC–MS/MS) was developed to determine carbamathione in vivo using microdialysis sampling from rat brain and plasma. Chromatographic separations were carried out on an Alltech Altima C-18 (50 mm long × 2.1 mm i.d., 3 μm particles) analytical column at a flow rate of 0.3 ml/min. Solvent A consisted of 10 mM ammonium formate, methanol, and formic acid (99:1:0.06, v/v/v). Solvent B consisted of methanol, 10 mM ammonium formate and formic acid (99:1:0.06, v/v/v). A 20 min linear gradient from 95% aqueous to 95% organic was used. Tandem mass spectra were acquired on a Micromass Quattro Ultima “triple” quadrupole mass spectrometer equipped with an ESI interface. Quantitative mass spectrometric analysis was conducted in positive ion mode selected reaction monitoring (SRM) mode looking at the transition of m/z 407–100 and 175 for carbamathione and m/z 392–263 for the internal standard S-hexyl glutathione. The simultaneous collection of microdialysate from blood and brain was used to monitor carbamathione concentrations centrally and peripherally. Good linearity was obtained over a concentration range of 0.25–10,000 nM. The lowest limit of quantification (LLOQ) was determined to be 1 nM and the lowest limit of detection (LLOD) was calculated to be 0.25 nM. Intra- and inter-day accuracy and precision were determined and for all the samples evaluated, the variability was less that 10% (R.S.D.). PMID:19709836

A neuropharmacokinetic assessment of bafetinib, a second generation dual BCR-Abl/Lyn tyrosine kinase inhibitor, in patients with recurrent high-grade gliomas.

PubMed

Portnow, Jana; Badie, Behnam; Markel, Susan; Liu, An; D'Apuzzo, Massimo; Frankel, Paul; Jandial, Rahul; Synold, Timothy W

2013-05-01

The primary objective of this study was to use intracerebral microdialysis (ICMD) to determine the neuropharmacokinetics of bafetinib, a dual BCR-Abl/Lyn tyrosine kinase inhibitor that may have activity against gliomas. A microdialysis catheter was placed into either peritumoural or enhancing brain tissue of seven patients at the time of tumour resection or biopsy. Twenty-four hours later, bafetinib was administered, 240 or 360 mg po, repeating the same dose 12 h later. Dialysate samples were continuously collected for 24h, with plasma samples obtained in parallel. One to two weeks after finishing ICMD, patients were allowed to resume taking bafetinib continuously while being observed for toxicity and tumour response. Twenty-six dialysate samples per patient were collected (n=6) and analysed for bafetinib by tandem mass spectrometry. Bafetinib concentrations in the brain were below the lower limit of detection of the assay (0.1 ng/ml) in all samples except one from a single subject that was 0.52 ng/ml. The mean plasma bafetinib maximum concentrations after dose 1 and 2 were 143±99 and 247±73 ng/ml, respectively. Only one patient remained on treatment past two cycles, and no radiographic responses were seen. Bafetinib does not sufficiently cross intact or disrupted blood-brain barrier, and therefore, systemic administration of bafetinib is not recommended when investigating this drug as a treatment for brain tumours. ICMD can be a valuable research tool in early drug development. Lead-in ICMD studies can be performed relatively quickly, requiring only a small number of patients, and without significantly disrupting standard cancer care. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of oxygen therapy on glucose-lactate metabolism after diffuse brain injury.

PubMed

Reinert, Michael; Schaller, Benoit; Widmer, Hans Rudolf; Seiler, Rolf; Bullock, Ross

2004-08-01

Severe traumatic brain injury (TBI) imposes a huge metabolic load on brain tissue, which can be summarized initially as a state of hypermetabolism and hyperglycolysis. In experiments O2 consumption has been shown to increase early after trauma, especially in the presence of high lactate levels and forced O2 availability. In recent clinical studies the effect of increasing O2 availability on brain metabolism has been analyzed. By their nature, however, clinical trauma models suffer from a heterogeneous injury distribution. The aim of this study was to analyze, in a standardized diffuse brain injury model, the effect of increasing the fraction of inspired O2 on brain glucose and lactate levels, and to compare this effect with the metabolism of the noninjured sham-operated brain. A diffuse severe TBI model developed by Foda and Maramarou, et al., in which a 420-g weight is dropped from a height of 2 m was used in this study. Forty-one male Wistar rats each weighing approximately 300 g were included. Anesthesized rats were monitored by placing a femoral arterial line for blood pressure and blood was drawn for a blood gas analysis. Two time periods were defined: Period A was defined as preinjury and Period B as postinjury. During Period B two levels of fraction of inspired oxygen (FiO2) were studied: air (FiO2 0.21) and oxygen (FiO2 1). Four groups were studied including sham-operated animals: air-air-sham (AAS); air-O2-sham (AOS); air-air-trauma (AAT); and air-O2-trauma (AOT). In six rats the effect of increasing the FiO2 on serum glucose and lactate was analyzed. During Period B lactate values in the brain determined using microdialysis were significantly lower (p < 0.05) in the AOT group than in the AAT group and glucose values in the brain determined using microdialysis were significantly higher (p < 0.04). No differences were demonstrated in the other groups. Increasing the FiO2 had no significant effect on the serum levels of glucose and lactate. Increasing the FiO2 influences dialysate glucose and lactate levels in injured brain tissue. Using an FiO2 of 1 influences brain metabolism in such a way that lactate is significantly reduced and glucose significantly increased. No changes in dialysate glucose and lactate values were found in the noninjured brain.

Proof of mechanism study of a novel serotonin transporter blocker, DA-8031, using [11C]DASB positron emission tomography and in vivo microdialysis.

PubMed

Park, Hyun Soo; Jung, In Soon; Lim, Nam Hee; Sung, Ji Hyun; Lee, Sukhyang; Moon, Byung Seok; Lee, Byung Chul; Kang, Kyung Koo; Kim, Sang Eun

2014-07-01

To investigate the efficacy of DA-8031, a novel compound for the treatment of premature ejaculation, we measured serotonin transporter (SERT) occupancy by DA-8031, as well as DA-8031-induced changes in extracellular serotonin levels, in the rat brain using positron emission tomography (PET) and 11C-N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine ([11C]DASB) and in vivo microdialysis, respectively. [11C]DASB PET scans were performed in rats with graded doses of DA-8031 (vehicle: 10, 30, and 100 mg/kg). SERT occupancy in the midbrain was determined using binding potentials for [11C]DASB calculated by the multilinear reference tissue model. Extracellular serotonin levels were monitored in the dorsal raphe nucleus of rats after the administration of DA-8031 (10-100 mg/kg) using in vivo microdialysis. PET data indicated a reduction of [11C]DASB binding to SERTs in the midbrain as a function of DA-8031 dose. SERT occupancy for each DA-8031 dose (10-100 mg/kg) ranged between 31% and 84%. The drug dose required for 50% occupancy of SERT was 13.5 mg/kg in the midbrain, comparable with previous preclinical behavioral data (∼10-30 mg/kg). In vivo microdialysis showed that DA-8031 produced a dose-dependent increase in extracellular serotonin levels in the dorsal raphe nucleus (33%-81% increase for doses of 10-100 mg/kg). These preclinical data provide a proof of mechanism for DA-8031 as a novel compound of targeting the SERT for the treatment of premature ejaculation, warranting further clinical trials. They also offer insight into the optimal drug dose needed to exert therapeutic effects while minimizing adverse effects in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

Microdialysis combined blood sampling technique for the determination of rosiglitazone and glucose in brain and blood of gerbils subjected to cerebral ischemia.

PubMed

Sheu, Wayne H-H; Chuang, Hsiu-Chun; Cheng, Shiu-Min; Lee, Maw-Rong; Chou, Chi-Chi; Cheng, Fu-Chou

2011-03-25

Rosiglitazone is a potent synthetic peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist which improves glucose control in the plasma and reduces ischemic brain injury. However, the pharmacokinetics of rosiglitazone in the brain is still unclear. In this study, a method using liquid chromatography-mass spectrometry coupled with microdialysis and an auto-blood sampling system was developed to determine rosiglitazone and glucose concentration in the brain and blood of gerbils subjected to treatment with rosiglitazone (3.0 mg kg(-1), i.p.). The results showed the limit of detection was 0.04 μg L(-1) and the correlation coefficient was 0.9997 for the determination of rosiglitazone in the brain. The mean parameters, maximum drug concentration (C(max)) and the area under the concentration-time curve from time zero to time infinity (AUC(inf)), following rosiglitazone administration were 1.06±0.28 μg L(-1) and 296.82±44.67 μg min L(-1), respectively. The time to peak concentration (C(max) or T(max)) of rosiglitazone occurred at 105±17.10 min, and the mean elimination half-life (t(1/2)) from brain was 190.81±85.18 min after administration of rosiglitazone. The brain glucose levels decreased to 71% of the basal levels in the rosiglitazone-treated group when compared with those in the control (p<0.01). Treatment with rosiglitazone decreased blood glucose levels to 80% at 1h after pretreatment of rosiglitazone (p<0.05). In addition, pretreatment with rosiglitazone significantly reduced the cerebral infarct volume compared with that of the control group. These findings suggest that this method may be useful for simultaneous and continuous determination of rosiglitazone and glucose concentrations in brain and plasma. Rosiglitazone was effective at penetrating the blood-brain barrier as evidenced by the rapid appearance of rosiglitazone in the brain, and rosiglitazone may contribute to a reduction in the extent of injuries related to cerebral ischemic stroke via its hypoglycemic effect. Copyright © 2010 Elsevier B.V. All rights reserved.

Enteral nutrition increases interstitial brain glucose levels in poor-grade subarachnoid hemorrhage patients.

PubMed

Kofler, Mario; Schiefecker, Alois J; Beer, Ronny; Gaasch, Maxime; Rhomberg, Paul; Stover, John; Pfausler, Bettina; Thomé, Claudius; Schmutzhard, Erich; Helbok, Raimund

2018-03-01

Low brain tissue glucose levels after acute brain injury are associated with poor outcome. Whether enteral nutrition (EN) reliably increases cerebral glucose levels remains unclear. In this retrospective analysis of prospectively collected observational data, we investigate the effect of EN on brain metabolism in 17 poor-grade subarachnoid hemorrhage (SAH) patients undergoing cerebral microdialysis (CMD) monitoring. CMD-values were obtained hourly. A nutritional intervention was defined as the clinical routine administration of EN without supplemental parenteral nutrition. Sixty-three interventions were analyzed. The mean amount of EN per intervention was 472.4 ± 10.7 kcal. CMD-glucose levels significantly increased from 1.59 ± 0.13 mmol/l at baseline to a maximum of 2.03 ± 0.2 mmol/l after 5 h (p < 0.001), independently of insulin-treatment, baseline serum glucose, baseline brain metabolic distress (CMD-lactate-to-pyruvate-ratio (LPR) > 40) and the microdialysis probe location. The increase in CMD-glucose was directly dependent on the magnitude of increase of serum glucose levels (p = 0.007). No change in CMD-lactate, CMD-pyruvate, CMD-LPR, or CMD-glutamate (p > 0.4) was observed. Routine EN also increased CMD-glucose even if baseline concentrations were critically low ( < 0.7 mmol/l, neuroglucopenia; p < 0.001). These results may have treatment implications regarding glucose management of poor-grade aneurysmal SAH patients.

Theanine, gamma-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats.

PubMed

Yamada, T; Terashima, T; Kawano, S; Furuno, R; Okubo, T; Juneja, L R; Yokogoshi, H

2009-01-01

Theanine (gamma-glutamylethylamide) is one of the major amino acid components in green tea and can pass through the blood-brain barrier. Recent studies suggest that theanine affects the mammalian central nervous system; however, the detailed mechanism remains unclear. In this study, we demonstrated the effect of theanine on neurotransmission in the brain striatum by in vivo brain microdialysis. Theanine injection into the rat brain striatum did not increase the concentration of excitatory neurotransmitters in the perfusate. On the other hand, theanine injection increased the concentration of glycine in the perfusate. Because it has been reported that theanine promotes dopamine release in the rat striatum, we investigated the glycine and dopamine concentrations in the perfusate. Co-injection of glycine receptor antagonist, strychnine, reduced theanine-induced changes in dopamine. Moreover, AMPA receptor antagonist, which regulates glycine and GABA release from glia cells, inhibited these effects of theanine and this result was in agreement with the known inhibitory effect of theanine at AMPA receptors.

A novel liquid chromatography/tandem mass spectrometry method for the quantification of glycine as biomarker in brain microdialysis and cerebrospinal fluid samples within 5min.

PubMed

Voehringer, Patrizia; Fuertig, René; Ferger, Boris

2013-11-15

Glycine is an important amino acid neurotransmitter in the central nervous system (CNS) and a useful biomarker to indicate biological activity of drugs such as glycine reuptake inhibitors (GRI) in the brain. Here, we report how a liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the fast and reliable analysis of glycine in brain microdialysates and cerebrospinal fluid (CSF) samples has been established. Additionally, we compare this method with the conventional approach of high performance liquid chromatography (HPLC) coupled to fluorescence detection (FD). The present LC-MS/MS method did not require any derivatisation step. Fifteen microliters of sample were injected for analysis. Glycine was detected by a triple quadrupole mass spectrometer in the positive electrospray ionisation (ESI) mode. The total running time was 5min. The limit of quantitation (LOQ) was determined as 100nM, while linearity was given in the range from 100nM to 100μM. In order to demonstrate the feasibility of the LC-MS/MS method, we measured glycine levels in striatal in vivo microdialysates and CSF of rats after administration of the commercially available glycine transporter 1 (GlyT1) inhibitor LY 2365109 (10mg/kg, p.o.). LY 2365109 produced 2-fold and 3-fold elevated glycine concentrations from 1.52μM to 3.6μM in striatal microdialysates and from 10.38μM to 36μM in CSF, respectively. In conclusion, we established a fast and reliable LC-MS/MS method, which can be used for the quantification of glycine in brain microdialysis and CSF samples in biomarker studies. Copyright © 2013 Elsevier B.V. All rights reserved.

In vivo microdialysis and electroencephalographic activity in freely moving guinea pigs exposed to organophosphorus nerve agents sarin and VX: analysis of acetylcholine and glutamate.

PubMed

O'Donnell, John C; McDonough, John H; Shih, Tsung-Ming

2011-12-01

Organophosphorus nerve agents such as sarin (GB) and VX irreversibly inhibit acetylcholinesterase, causing a buildup of acetylcholine (ACh) in synapses and neuromuscular junctions, which leads to excess bronchial secretions, convulsions, seizures, coma, and death. Understanding the unique toxic characteristics of different nerve agents is vital in the effort to develop broad spectrum medical countermeasures. To this end, we employed a repeated measure multivariate design with striatal microdialysis collection and high-performance liquid chromatography analysis to measure changes in concentrations of several neurotransmitters (ACh, glutamate, aspartate, GABA) in the same samples during acute exposure to GB or VX in freely moving guinea pigs. Concurrent with microdialysis collection, we used cortical electrodes to monitor brain seizure activity. This robust double multivariate design provides greater fidelity when comparing data while also reducing the required number of subjects. No correlation between nerve agents' propensity for causing seizure and seizure-related lethality was observed. The GB seizure group experienced more rapid and severe cholinergic toxicity and lethality than that of the VX seizure group. Seizures generated from GB and VX exposure resulted in further elevation of ACh level and then a gradual return to baseline. Glutamate levels increased in the GB, but not in the VX, seizure group. There were no consistent changes in either aspartate or GABA as a result of either nerve agent. These observations reinforce findings with other nerve agents that seizure activity per se contributes to the elevated levels of brain ACh observed after nerve agent exposure.

[Microdialysis cerebral. Main application of this technique].

PubMed

Blanco-Lezcano, L; Pavón-Fuentes, N; Blanco-Lezcano, V

Microdialysis cerebral technique has been widely employed in order to study the neurotransmitter release. This technique present numerous advantages such as: allow to work with sample in vivo from animals freely moving, by means of microdialysis can be infused simultaneously different drugs in different points implanted probes in several coordinates; also allow carry out pharmacokinetics studies that show correlation with behavior patter as well as to study metabolic changes, which is not possible when this determination are carry out in tissue, in post mortem stadio. In the present work is carry out a review about the main results obtaining in the sensitization and abstinence to several drug study and approach to biochemical characteristics to Parkinson s disease (PD) by means of microdialysis technique. In relation to sensibilization studies, the temporal changes in different behavior pattern that modify after amphetamine administration have been studied. Microdialysis study allowed correlationate dopamine concentration with behavior pattern above mentioned. In relation with PD, dopamine concentration after systemic and central (intracerebral) administration of levodopa and another dopaminergic drugs have been studied in different nucleus of basal ganglia as well as its respectively behavior correlates.

Striking differences in glucose and lactate levels between brain extracellular fluid and plasma in conscious human subjects: effects of hyperglycemia and hypoglycemia.

PubMed

Abi-Saab, Walid M; Maggs, David G; Jones, Tim; Jacob, Ralph; Srihari, Vinod; Thompson, James; Kerr, David; Leone, Paola; Krystal, John H; Spencer, Dennis D; During, Matthew J; Sherwin, Robert S

2002-03-01

Brain levels of glucose and lactate in the extracellular fluid (ECF), which reflects the environment to which neurons are exposed, have never been studied in humans under conditions of varying glycemia. The authors used intracerebral microdialysis in conscious human subjects undergoing electrophysiologic evaluation for medically intractable epilepsy and measured ECF levels of glucose and lactate under basal conditions and during a hyperglycemia-hypoglycemia clamp study. Only measurements from nonepileptogenic areas were included. Under basal conditions, the authors found the metabolic milieu in the brain to be strikingly different from that in the circulation. In contrast to plasma, lactate levels in brain ECF were threefold higher than glucose. Results from complementary studies in rats were consistent with the human data. During the hyperglycemia-hypoglycemia clamp study the relationship between plasma and brain ECF levels of glucose remained similar, but changes in brain ECF glucose lagged approximately 30 minutes behind changes in plasma. The data demonstrate that the brain is exposed to substantially lower levels of glucose and higher levels of lactate than those in plasma; moreover, the brain appears to be a site of significant anaerobic glycolysis, raising the possibility that glucose-derived lactate is an important fuel for the brain.

Blood-brain barrier penetration of novel pyridinealdoxime methiodide (PAM)-type oximes examined by brain microdialysis with LC-MS/MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okuno, Sou; Sakurada, Koichi; Ohta, Hikoto

2008-02-15

To develop a new reactivator of inhibited acetylcholinesterase (AChE) that can easily penetrate the blood-brain barrier (BBB), BBB penetration of 6 known and novel pyridinealdoxime methiodide (PAM)-type oximes (alkylPAMs) with relatively high reactivation activities was examined by in vivo rat brain microdialysis with liquid chromatography-mass spectrometry (LC-MS/MS). The 50% lethal dose (LD{sub 50}) of alkylPAMs was intravenously determined for Wistar rats, then the limit of detection, quantification range and linearity of the calibration curve of the alkylPAMs in dialysate and blood were determined by LC-MS/MS. Following 10% LD{sub 50} intravenous administration of the alkylPAMs, 4-[(hydroxyimino) methyl]-1-(2-phenylethyl) pyridinium bromide (4-PAPE) andmore » 4-[(hydroxyimino) methyl]-1-octylpyridinium bromide (4-PAO) appeared in the dialysate. Striatal extracellular fluid/blood concentration ratios were 0.039 {+-} 0.018 and 0.301 {+-} 0.183 (mean {+-} SEM), respectively, 1 h after treatment. This is the first report of BBB penetration of 4-PAPE, and the concentration ratio was smaller than that of 2-PAM.The mean BBB penetration of 4-PAO was approximately 30%, indicating that intravenous administration of 4-PAO may be effective for the reactivation of blocked cholinesterase in the brain. However, the toxicity of 4-PAO (LD{sub 50}; 8.89 mg/kg) was greater than that of 2-PAM. Further investigation is required to determine the effects of these alkylPAMs in organophosphate poisoning.« less

Enhancement of in vivo antioxidant ability in the brain of rats fed tannin.

PubMed

Nakajima, Akira; Ueda, Yuto; Matsuda, Emiko; Sameshima, Hiroshi; Ikenoue, Tsuyomu

2013-07-01

The effect of the oral administration of mimosa tannin (MMT) on the rat intra-hippocampal antioxidant ability was examined. Wistar rats at the age of 6 weeks were reared for 8 weeks with the rodent diet (RD) consisting of 0.1 g/kg of MMT (RD-MMT). The antioxidant ability of rat brain was evaluated from the decay of a brain-blood-barrier permeable stable nitroxide, 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM) measured by the microdialysis-electron spin resonance system under a freely moving state. The decay rate of PCAM in the brain of rats fed RD-MMT was significantly larger than that of rats fed control rodent diet, which indicates the increase of the antioxidant ability in the brain of rats fed RD-MMT. In vitro study showed that MMT did not reduce PCAM directly but enhanced the reduction of PCAM by ascorbic acid. These results indicate that MMT is a potent antioxidant in vitro and in vivo.

Trans-synaptic (GABA-dopamine) modulation of cocaine induced dopamine release: A potential therapeutic strategy for cocaine abuse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dewey, S.L.; Straughter-Moore, R.; Chen, R.

We recently developed a new experimental strategy for measuring interactions between functionally-linked neurotransmitter systems in the primate and human brain with PET. As part of this research, we demonstrated that increases in endogenous GABA concentrations significantly reduced striatal dopamine concentrations in the primate brain. We report here the application of the neurotransmitter interaction paradigm with PET and with microdialysis to the investigation of a novel therapeutic strategy for treating cocaine abuse based on the ability of GABA to inhibit cocaine induced increases in striatal dopamine. Using gamma-vinyl GABA (GVG, a suicide inhibitor of GABA transaminase), we performed a series ofmore » PET studies where animals received a baseline PET scan with labeled raclopride injection, animals received cocaine (2.0 mg/kg). Normally, a cocaine challenge significantly reduces the striatal binding of {sup 11}C-raclopride. However, in animals pretreated with GVG, {sup 11}C-raclopride binding was less affected by a cocaine challenge compared to control studies. Furthermore, microdialysis studies in freely moving rats demonstrate that GVG (300 mg/kg) significantly inhibited cocaine-induced increases in extracellular dopamine release. GVG also attenuated cocaine-induced increases in locomotor activity. However, at a dose of 100 mg/kg, GVG had no effect. Similar findings were obtained with alcohol. Alcohol pretreatment dose dependantly (1-4 g/kg) inhibited cocaine-induced increases in extracellular dopamine concentrations in freely moving rats. Taken together, these studies suggest that therapeutic strategies targeted at increasing central GABA concentrations may be beneficial for the treatment of cocaine abuse.« less

Neural Stem Cell-Based Anticancer Gene Therapy: A First-in-Human Study in Recurrent High-Grade Glioma Patients.

PubMed

Portnow, Jana; Synold, Timothy W; Badie, Behnam; Tirughana, Revathiswari; Lacey, Simon F; D'Apuzzo, Massimo; Metz, Marianne Z; Najbauer, Joseph; Bedell, Victoria; Vo, Tien; Gutova, Margarita; Frankel, Paul; Chen, Mike; Aboody, Karen S

2017-06-15

Purpose: Human neural stem cells (NSC) are inherently tumor tropic, making them attractive drug delivery vehicles. Toward this goal, we retrovirally transduced an immortalized, clonal NSC line to stably express cytosine deaminase (HB1.F3.CD.C21; CD-NSCs), which converts the prodrug 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU). Experimental Design: Recurrent high-grade glioma patients underwent intracranial administration of CD-NSCs during tumor resection or biopsy. Four days later, patients began taking oral 5-FC every 6 hours for 7 days. Study treatment was given only once. A standard 3 + 3 dose escalation schema was used to increase doses of CD-NSCs from 1 × 10 7 to 5 × 10 7 and 5-FC from 75 to 150 mg/kg/day. Intracerebral microdialysis was performed to measure brain levels of 5-FC and 5-FU. Serial blood samples were obtained to assess systemic drug concentrations as well as to perform immunologic correlative studies. Results: Fifteen patients underwent study treatment. We saw no dose-limiting toxicity (DLT) due to the CD-NSCs. There was 1 DLT (grade 3 transaminitis) possibly related to 5-FC. We did not see development of anti-CD-NSC antibodies and did not detect CD-NSCs or replication-competent retrovirus in the systemic circulation. Intracerebral microdialysis revealed that CD-NSCs produced 5-FU locally in the brain in a 5-FC dose-dependent manner. Autopsy data indicate that CD-NSCs migrated to distant tumor sites and were nontumorigenic. Conclusions: Collectively, our results from this first-in-human study demonstrate initial safety and proof of concept regarding the ability of NSCs to target brain tumors and locally produce chemotherapy. Clin Cancer Res; 23(12); 2951-60. ©2016 AACR . ©2016 American Association for Cancer Research.

Acute Effects of Muscarinic M1 Receptor Modulation on AβPP Metabolism and Amyloid-β Levels in vivo: A Microdialysis Study.

PubMed

Welt, Tobias; Kulic, Luka; Hoey, Sarah E; McAfoose, Jordan; Späni, Claudia; Chadha, Antonella Santuccione; Fisher, Abraham; Nitsch, Roger M

2015-01-01

Indirect modulation of cholinergic activity by cholinesterase inhibition is currently a widely established symptomatic treatment for Alzheimer's disease (AD). Selective activation of certain muscarinic receptor subtypes has emerged as an alternative cholinergic-based amyloid-lowering strategy for AD, as selective muscarinic M1 receptor agonists can reduce amyloid-β (Aβ) production by shifting endoproteolytic amyloid-β protein precursor (AβPP) processing toward non-amyloidogenic pathways. In this study, we addressed the hypothesis that acute stimulation of muscarinic M1 receptors can inhibit Aβ production in awake and freely moving AβPP transgenic mice. By combining intracerebral microdialysis with retrodialysis, we determined hippocampal Aβ concentrations during simultaneous pharmacological modulation of brain M1 receptor function. Infusion with a M1 receptor agonist AF102B resulted in a rapid reduction of interstitial fluid (ISF) Aβ levels while treatment with the M1 antagonist dicyclomine increased ISF Aβ levels reaching significance within 120 minutes of treatment. The reduction in Aβ levels was associated with PKCα and ERK activation resulting in increased levels of the α-secretase ADAM17 and a shift in AβPP processing toward the non-amyloidogenic processing pathway. In contrast, treatment with the M1 receptor antagonist dicyclomine caused a decrease in levels of phosphorylated ERK that was independent of PKCα, and led to an elevation of β-secretase levels associated with increased amyloidogenic AβPP processing. The results of this study demonstrate rapid effects of in vivo M1 receptor modulation on the ISF pool of Aβ and suggest that intracerebral microdialysis with retrodialysis is a useful technical approach for monitoring acute treatment effects of muscarinic receptor modulators on AβPP/Aβ metabolism.

Association of brain metabolites with blood lactate and glucose levels with respect to neurological outcomes after out-of-hospital cardiac arrest: A preliminary microdialysis study.

PubMed

Hifumi, Toru; Kawakita, Kenya; Yoda, Takeshi; Okazaki, Tomoya; Kuroda, Yasuhiro

2017-01-01

Out-of-hospital cardiac arrest (OHCA) is associated with poor prognosis. Cerebral microdialysis (CMD) is an efficient sampling technique to detect neurochemical changes in brain interstitial tissue. In this retrospective study, we hypothesised that there are different CMD levels between patients with favourable and unfavourable neurological outcomes. Data of patients with OHCA admitted to Kagawa University Hospital and administered therapeutic hypothermia (TH) were collected. Using a CMD probe, extracellular glucose, lactate and pyruvate levels were measured hourly along with intracranial perfusion pressure (ICP) and cerebral perfusion pressure (CPP) for the initial 72h during TH. The lactate/pyruvate (LP) ratio was calculated. Patients were divided into favourable [Glasgow-Pittsburgh cerebral performance category 1-2 at 30days after cardiac arrest] or unfavourable neurological outcome groups. CMD biochemical markers and blood lactate and glucose levels were compared between two groups. Ten patients were included. ICP was significantly higher in the unfavourable than in the favourable neurological outcome group; there were no significant differences with respect to CPP. The CMD LP ratio in the unfavourable outcome group progressively increased; significant differences were observed on days 2, 3 and 4 (p<0.01). Significant differences in blood lactate levels were observed between the groups only on day 3.5. CMD and blood glucose levels were higher in the unfavourable than in the favourable outcome group during TH. The association of CMD levels with long-term outcomes would be better defined in a large randomised prospective study. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Assessment of blood-brain barrier penetration: in silico, in vitro and in vivo.

PubMed

Feng, Meihua Rose

2002-12-01

The amount of drug achieved and maintained in the brain after systemic administration is determined by the agent's permeability at blood-brain barrier (BBB), potential involvement of transport systems, and the distribution, metabolism and elimination properties. Passive diffusion permeability may be predicted by an in silico method based on a molecule's structure property. In vitro cell culture is another useful tool for the assessment of passive permeability and BBB transports (e.g. PGP, MRP). In situ or in vivo techniques like carotid artery single injection or perfusion, brain microdialysis, autoradiography, and others are used at various stages of drug discovery and development to estimate CNS penetration and PK/PD correlation. Each technique has its own application with specific advantages and limitations.

Microdialysis Monitoring of CSF Parameters in Severe Traumatic Brain Injury Patients: A Novel Approach

PubMed Central

Thelin, Eric P.; Nelson, David W.; Ghatan, Per Hamid; Bellander, Bo-Michael

2014-01-01

Background: Neuro-intensive care following traumatic brain injury (TBI) is focused on preventing secondary insults that may lead to irreversible brain damage. Microdialysis (MD) is used to detect deranged cerebral metabolism. The clinical usefulness of the MD is dependent on the regional localization of the MD catheter. The aim of this study was to analyze a new method of continuous cerebrospinal fluid (CSF) monitoring using the MD technique. The method was validated using conventional laboratory analysis of CSF samples. MD-CSF and regional MD-Brain samples were correlated to patient outcome. Materials and Methods: A total of 14 patients suffering from severe TBI were analyzed. They were monitored using (1) a MD catheter (CMA64-iView, n = 7448 MD samples) located in a CSF-pump connected to the ventricular drain and (2) an intraparenchymal MD catheter (CMA70, n = 8358 MD samples). CSF-lactate and CSF-glucose levels were monitored and were compared to MD-CSF samples. MD-CSF and MD-Brain parameters were correlated to favorable (Glasgow Outcome Score extended, GOSe 6–8) and unfavorable (GOSe 1–5) outcome. Results: Levels of glucose and lactate acquired with the CSF-MD technique could be correlated to conventional levels. The median MD recovery using the CMA64 catheter in CSF was 0.98 and 0.97 for glucose and lactate, respectively. Median MD-CSF (CMA 64) lactate (p = 0.0057) and pyruvate (p = 0.0011) levels were significantly lower in the favorable outcome group compared to the unfavorable group. No significant difference in outcome was found using the lactate:pyruvate ratio (LPR), or any of the regional MD-Brain monitoring in our analyzed cohort. Conclusion: This new technique of global MD-CSF monitoring correlates with conventional CSF levels of glucose and lactate, and the MD recovery is higher than previously described. Increase in lactate and pyruvate, without any effect on the LPR, correlates to unfavorable outcome, perhaps related to the presence of erythrocytes in the CSF. PMID:25228896

Characteristics of basal taurine release in the rat striatum measured by microdialysis.

PubMed

Molchanova, S; Oja, S S; Saransaari, P

2004-12-01

Taurine is a sulfur-containing amino acid thought to be an osmoregulator, neurotransmitter or neuromodulator in the brain. Our objective was to establish how much taurine is released in the striatum and examine the mechanisms controlling extracellular taurine concentrations under resting conditions. The experiments were made on rats by microdialysis in vivo. Changes in taurine were compared with those in glutamate, glycine and the non-neuroactive amino acid threonine. Using the zero net flux approach we showed the extracellular concentration of taurine to be 25.2 +/- 5.1 muM. Glutamate was increased by tetrodotoxin and decreased by Ca2+ omission, glycine and threonine were not affected and both treatments increased extracellular taurine. The basal taurine release was increased by the taurine transport inhibitor guanidinoethanesulfonate and reduced by the anion channel blocker 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid.

Accumbal strychnine-sensitive glycine receptors: an access point for ethanol to the brain reward system.

PubMed

Molander, Anna; Söderpalm, Bo

2005-01-01

Ethanol (EtOH), like other drugs of abuse, increases extracellular dopamine (DA) levels in the nucleus accumbens (nAc) of the brain reward system, an effect that may be of importance for alcohol addiction. How this DA increase is produced is not fully understood, although previous studies from the present laboratories indicate that nicotinic acetylcholine receptors in the ventral tegmental area play an important role in mediating this effect. Furthermore, activation of these receptors may be secondary to some priming effect produced by EtOH in the nAc. We recently demonstrated that strychnine-sensitive glycine receptors (GlyRs) are present in the nAc and that they are involved in regulating extracellular DA levels. Here we examine the tentative role of these accumbal GlyRs in the above-mentioned priming mechanism of EtOH. In vivo microdialysis (coupled to high pressure liquid chromatography with electrochemical detection) and reversed microdialysis, in awake, freely moving adult male Wistar rats. Local perfusion of strychnine decreased accumbal DA levels per se and completely prevented the increase of accumbal DA levels after both local and systemic EtOH administration. Accumbal perfusion of the GlyR agonist glycine instead increased DA levels in a subpopulation of rats and prevented the EtOH-induced increase after local but not systemic EtOH in all animals. The present results suggest that GlyRs in the nAc might constitute targets for EtOH in its mesolimbic DA-activating effect. Gene polymorphism and drug developmental studies that focus on this receptor population and its relation to alcohol dependence are warranted.

Animal models for studying transport across the blood-brain barrier.

PubMed

Bonate, P L

1995-01-01

There are many reasons for wishing to determine the rate of uptake of a drug from blood into brain parenchyma. However, when faced with doing so for the first time, choosing a method can be a formidable task. There are at least 7 methods from which to choose: indicator dilution, brain uptake index, microdialysis, external registration, PET scanning, in situ perfusion, and compartmental modeling. Each method has advantages and disadvantages. Some methods require very little equipment while others require equipment that can cost millions of dollars. Some methods require very little technical experience whereas others require complex surgical manipulation. The mathematics alone for the various methods range from simple algebra to complex integral calculus and differential equations. Like most things in science, as the complexity of the technique increases, so does the quantity of information it provides. This review is meant to serve as a starting point for the researcher who wishes to study transport and uptake across the blood-brain barrier in animal models. An overview of the mathematical theory, as well as an introduction to the techniques, is presented.

Water-soluble cyclodextrin polymers for enhanced relative recovery of hydrophobic analytes during microdialysis sampling.

PubMed

Ao, Xiaoping; Stenken, Julie A

2003-09-01

Microdialysis relative recovery (RR) enhancement using different water-soluble, epichlorohydrin-based cyclodextrin polymers (CD-EPS) was studied in vitro for different analytes, amitryptiline, carbamazepine, hydroquinone, ibuprofen, and 4-nitrophenol. When compared to the native CDs (alpha, beta, and gamma) on a per mole basis, the CD-EPS enhanced microdialysis RR was either statistically greater or the same. beta-CD-EPS was more highly retained than native beta-CD by a 20 000 Da molecular weight cutoff (MWCO) polycarbonate membrane, but showed no statistical difference for loss across a 100 000 Da MWCO polyethersulfone membrane (PES). When the same weight percent of beta-CD or beta-CD-EPS was included in the microdialysis perfusion fluid, the beta-CD-EPS produced a higher microdialysis RR than native beta-CD for all analytes across the PES membrane. However, enhancements for the PC membrane were statistically insignificant when beta-CD and beta-CD-EPS were compared on a per mole basis. These results suggest that CD-EPS may be used as effective enhancement agents during microdialysis sampling and for some membranes provide the additional advantage of being retained more than native CDs.

Abnormality of circadian rhythm accompanied by an increase in frontal cortex serotonin in animal model of autism.

PubMed

Tsujino, Naohisa; Nakatani, Yasushi; Seki, Yoshinari; Nakasato, Akane; Nakamura, Michiko; Sugawara, Michiya; Arita, Hideho

2007-02-01

Several clinical reports have indicated that autistic patients often show disturbance of the circadian rhythm, which may be related to dysfunction of the serotonergic system in the brain. Using rats exposed prenatally to valproic acid (VPA) as an animal model of autism, we examined locomotor activity and feeding under a reversed 12-h light/dark cycle, and found disturbance of the circadian rhythm characterized by frequent arousal during the light/sleep phase. In addition, measurement of brain serotonin (5-HT) level using in vivo microdialysis showed that the brain 5-HT level in VPA-exposed rats was significantly higher than that in control rats. These results suggest that a higher brain 5-HT level might be responsible for the irregular sleep/awake rhythm in autism.

Proton Resonance Spectroscopy Study of the Effects of L-Ornithine-L-Aspartate on the Development of Encephalopathy, Using Localization Pulses with Reduced Specific Absorption Rate

NASA Astrophysics Data System (ADS)

Slotboom, J.; Vogels, B. A. P. M.; Dehaan, J. G.; Creyghton, J. H. N.; Quack, G.; Chamuleau, R. A. F. M.; Bovee, W. M. M. J.

Using the SADLOVE ( single-shot adiabatic localized volume excitation) localization technique with reduced specific absorption rate phase-compensated 2π pulses for localization, in vivo rat brain spectra were obtained in order to study the possible beneficial effects of L-ornithine-L-aspartate (OA) on the development of encephalopathy induced by hyperammonemia in portacaval shunted rats, an experimental model for subacute hepatic encephalopathy. The in vivo1H spectra were quantified using a conjugate-gradient-based frequency-domain fitting procedure. OA treatment resulted in an about threefold lower increase in train lactate ( P < 0.0001) and a slower increase of brain glutamine ( P = 0.022) concentration. However, these changes in brain metabolism, including a significantly lower ammonia concentration during OA treatment, were not associated with a sig significant improvement in clinical symptoms of encephalopathy, suggesting either insufficient decrease in brain ammonia concentration or another effect of OA treatment counteracting the lowering effect on blood and brain ammonia and on brain glutamine and lactate. It is concluded that localized in vivo1H MRS of the brain in combination with other analytical techniques, such as in vivo microdialysis, is helpful in explaining pathophysiological changes during hyperammonemia-induced encephalopathy.

Characterization of the effects of reuptake and hydrolysis inhibition on interstitial endocannabinoid levels in the brain: an in vivo microdialysis study.

PubMed

Wiskerke, Joost; Irimia, Cristina; Cravatt, Benjamin F; De Vries, Taco J; Schoffelmeer, Anton N M; Pattij, Tommy; Parsons, Loren H

2012-05-16

The present experiments employed in vivo microdialysis to characterize the effects of commonly used endocannabinoid clearance inhibitors on basal and depolarization-induced alterations in interstitial endocannabinoid levels in the nucleus accumbens of rat brain. Compounds targeting the putative endocannabinoid transporter and hydrolytic enzymes (FAAH and MAGL) were compared. The transporter inhibitor AM404 modestly enhanced depolarization-induced increases in 2-arachidonoyl glycerol (2-AG) levels but did not alter levels of N-arachidonoyl-ethanolamide (anandamide, AEA). The transport inhibitor UCM707 did not alter dialysate levels of either endocannabinoid. The FAAH inhibitors URB597 and PF-3845 robustly increased AEA levels during depolarization without altering 2-AG levels. The MAGL inhibitor URB602 significantly enhanced depolarization-induced increases in 2-AG, but did not alter AEA levels. In contrast, the MAGL inhibitor JZL184 did not alter 2-AG or AEA levels under any condition tested. Finally, the dual FAAH/MAGL inhibitor JZL195 significantly enhanced depolarization-induced increases in both AEA and 2-AG levels. In contrast to the present observations in rats, prior work in mice has demonstrated a robust JZL184-induced enhancement of depolarization-induced increases in dialysate 2-AG. Thus, to further investigate species differences, additional tests with JZL184, PF-3845, and JZL195 were performed in mice. Consistent with prior reports, JZL184 significantly enhanced depolarization-induced increases in 2-AG without altering AEA levels. PF-3845 and JZL195 produced profiles in mouse dialysates comparable to those observed in rats. These findings confirm that interstitial endocannabinoid levels in the brain can be selectively manipulated by endocannabinoid clearance inhibitors. While PF-3845 and JZL195 produce similar effects in both rats and mice, substantial species differences in JZL184 efficacy are evident, which is consistent with previous studies.

Analytical and Biological Methods for Probing the Blood-Brain Barrier

PubMed Central

Sloan, Courtney D. Kuhnline; Nandi, Pradyot; Linz, Thomas H.; Aldrich, Jane V.; Audus, Kenneth L.; Lunte, Susan M.

2013-01-01

The blood-brain barrier (BBB) is an important interface between the peripheral and central nervous systems. It protects the brain against the infiltration of harmful substances and regulates the permeation of beneficial endogenous substances from the blood into the extracellular fluid of the brain. It can also present a major obstacle in the development of drugs that are targeted for the central nervous system. Several methods have been developed to investigate the transport and metabolism of drugs, peptides, and endogenous compounds at the BBB. In vivo methods include intravenous injection, brain perfusion, positron emission tomography, and microdialysis sampling. Researchers have also developed in vitro cell-culture models that can be employed to investigate transport and metabolism at the BBB without the complication of systemic involvement. All these methods require sensitive and selective analytical methods to monitor the transport and metabolism of the compounds of interest at the BBB. PMID:22708905

Participation of hippocampal agmatine in spatial learning: an in vivo microdialysis study.

PubMed

Rushaidhi, Madihah; Jing, Yu; Zhang, Hu; Liu, Ping

2013-02-01

Agmatine, decarboxylated arginine, is widely distributed in mammalian brains and is considered as a novel putative neurotransmitter. Recent research demonstrates spatial learning-induced increases in agmatine in memory-related structures at the tissue and presynaptic terminal levels. By using the in vivo microdialysis technique coupled with highly sensitive liquid chromatography/mass spectrometry assay, we investigated dynamic changes of extracellular agmatine in the rat dorsal hippocampus before, during and after water maze training to find a fixed hidden platform on the first and forth day of testing. It was firstly noted that the basal level of extracellular agmatine was significantly elevated on day 4. While swimming per se had no effect, a rapid rise (2-6 folds) in extracellular agmatine was observed during water maze training regardless of testing day. Such learning-induced rise was found to successively lessen across the multiple blocks of training on day 1. However, this pattern was reversed on day 4 when the platform was removed during the final training trial. The present study, for the first time, demonstrates water maze training-induced increase of extracellular agmatine in the dorsal hippocampus. The results suggest a role of endogenous agmatine in the encoding and retrieval of spatial information. Copyright © 2012 Elsevier Ltd. All rights reserved.

Brain Damage Caused by Chemical Warfare Agents: Are Free Radicals a Final Common Pathway?

DTIC Science & Technology

1998-08-01

to methemoglobin (Fe(III); MetHb), simultaneously releasing nitrate (Feelisch and Noack, 1987; Archer, 1993,). An analytical approach to measure NO...NO analysis such as measurement of nitrite and nitrate by the Griess assay or HPLC-conductivity detection (Green et al., 1982; Lippsmeyer et al., 1990...enzyme nitrate reductase. Although other groups have claimed to use the Griess reaction with microdialysis samples, we have found the Griess reaction

Neurotransmitters and pathophysiology of stroke: evidence for the release of glutamate and other transmitters/mediators in animals and humans.

PubMed

Dávalos, A; Shuaib, A; Wahlgren, N G

2000-11-01

There is convincing evidence from animal models of stroke that ischemia leads to an increase in the extracellular concentrations of excitatory amino acids (EAAs), especially glutamate. This accumulation of glutamate, which can reach up to 80 times normal at the centre of an ischemic lesion, is believed to be an important factor for the premature death of neurons that would otherwise survive the ischemic conditions and recover when flow is restored. In the technique of microdialysis, a small probe is inserted into the brain tissue. Fluid passing through the probe is separated from the brain parenchyma by a semipermeable membrane, through which substances released into the brain can diffuse. Analysis of the dialysate allows the nature and time course of release of substances, such as glutamate, to be determined. This technique has been used in patients undergoing resection of cerebral tumors, surgery for epilepsy, head trauma, subarachnoid hemorrhage, and cerebral infarction. Clamping or ligating the blood supply to the lobe about to be excised leads to a rapid accumulation in the dialysate of, among other substances, glutamate. Similar findings have been obtained during lobar resection for the treatment of severe epilepsy. Accumulations of glutamate to approximately 100 times the basal concentration have been found. There are also a few reports of microdialysis being performed in patients undergoing lobectomy after severe strokes or extracranial-intracranial bypass surgery. Again, high concentrations of glutamate have been reported. Another approach is to examine the blood and cerebrospinal fluid (CSF) for traces of EAAs. High concentrations of glutamate have been found in the blood and CSF within 24 hours of the onset of stroke. In animal models, plasma concentrations of glutamate begin to rise some 4 to 6 hours after middle cerebral artery (MCA) occlusions, reaching a peak at about 8 to 24 hours. Similarly, when glutamate is injected into the CSF of rats, there is a lag of approximately 4 hours before the concentration of glutamate in the blood rises. Therefore, it may be possible to detect the ongoing release of glutamate into the brain as a result of cerebral ischemia, which may aid in the selection of the most appropriate treatment. The results of microdialysis and plasma EAA analyses suggest that excitotoxic damage can occur over many hours. This implies that effective neuroprotectant strategies could provide clinical benefits over similarly prolonged periods.

Skin microdialysis coupled with laser speckle contrast imaging to assess microvascular reactivity.

PubMed

Cracowski, J L; Gaillard-Bigot, F; Cracowski, C; Roustit, M; Millet, C

2011-11-01

Laser speckle contrast imaging (LSCI) can be used to assess real-time responses of skin microcirculation to pharmacological interventions. The main objective of this study was to determine whether intradermal or subdermal microdialysis fiber insertion, coupled with skin flux recording using LSCI, can be used to assess baseline cutaneous flux and the post-occlusive reactive hyperemic response. The microdialysis sites were compared to control area without microdialysis fibers. One dermal and two subdermal microdialysis fibers were randomly inserted in the right forearm skin of six healthy volunteers. We performed consecutively tests of post-occlusive hyperemia, infusion of 29 mM sodium nitroprusside (SNP), local thermal hyperemia at 43°C and a second 29 mM SNP infusion at the end of the experiment. Two hours after fiber insertion, cutaneous vascular conductances (CVC) at the subdermal fiber sites were not different from their respective control regions of interest, while at the dermal site CVC remained higher (0.48+/-0.15 versus 0.37+/-0.1 PU.mm Hg(-1), P=0.003). The peak CVC and area under the curve observed during post-occlusive reactive hyperemia were similar at all fiber sites and their respective controls. We observed a similar increase in CVC using 29 mM SNP infusion, 40 min local heating at 43°C, and their combination. Finally, physiological and pharmacological responses of the subdermal sites were reproducible in terms of amplitude, whether expressed as raw CVC or as % CVCmax. We showed that studying skin microvascular physiological or pharmacological responses using inserted subdermal microdialysis fibers coupled with LSCI is feasible and reproducible, and provides two-dimensional information. This technique will be useful for future mechanistic studies of skin microcirculation. Copyright © 2011 Elsevier Inc. All rights reserved.

Extracellular metabolites in the cortex and hippocampus of epileptic patients.

PubMed

Cavus, Idil; Kasoff, Willard S; Cassaday, Michael P; Jacob, Ralph; Gueorguieva, Ralitza; Sherwin, Robert S; Krystal, John H; Spencer, Dennis D; Abi-Saab, Walid M

2005-02-01

Interictal brain energy metabolism and glutamate-glutamine cycling are impaired in epilepsy and may contribute to seizure generation. We used the zero-flow microdialysis method to measure the extracellular levels of glutamate, glutamine, and the major energy substrates glucose and lactate in the epileptogenic and the nonepileptogenic cortex and hippocampus of 38 awake epileptic patients during the interictal period. Depth electrodes attached to microdialysis probes were used to identify the epileptogenic and the nonepileptogenic sites. The epileptogenic hippocampus had surprisingly high basal glutamate levels, low glutamine/glutamate ratio, high lactate levels, and indication for poor glucose utilization. The epileptogenic cortex had only marginally increased glutamate levels. We propose that interictal energetic deficiency in the epileptogenic hippocampus could contribute to impaired glutamate reuptake and glutamate-glutamine cycling, resulting in persistently increased extracellular glutamate, glial and neuronal toxicity, increased lactate production together with poor lactate and glucose utilization, and ultimately worsening energy metabolism. Our data suggest that a different neurometabolic process underlies the neocortical epilepsies.

Cholinergic Neurons in the Basal Forebrain Promote Wakefulness by Actions on Neighboring Non-Cholinergic Neurons: An Opto-Dialysis Study.

PubMed

Zant, Janneke C; Kim, Tae; Prokai, Laszlo; Szarka, Szabolcs; McNally, James; McKenna, James T; Shukla, Charu; Yang, Chun; Kalinchuk, Anna V; McCarley, Robert W; Brown, Ritchie E; Basheer, Radhika

2016-02-10

Understanding the control of sleep-wake states by the basal forebrain (BF) poses a challenge due to the intermingled presence of cholinergic, GABAergic, and glutamatergic neurons. All three BF neuronal subtypes project to the cortex and are implicated in cortical arousal and sleep-wake control. Thus, nonspecific stimulation or inhibition studies do not reveal the roles of these different neuronal types. Recent studies using optogenetics have shown that "selective" stimulation of BF cholinergic neurons increases transitions between NREM sleep and wakefulness, implicating cholinergic projections to cortex in wake promotion. However, the interpretation of these optogenetic experiments is complicated by interactions that may occur within the BF. For instance, a recent in vitro study from our group found that cholinergic neurons strongly excite neighboring GABAergic neurons, including the subset of cortically projecting neurons, which contain the calcium-binding protein, parvalbumin (PV) (Yang et al., 2014). Thus, the wake-promoting effect of "selective" optogenetic stimulation of BF cholinergic neurons could be mediated by local excitation of GABA/PV or other non-cholinergic BF neurons. In this study, using a newly designed opto-dialysis probe to couple selective optical stimulation with simultaneous in vivo microdialysis, we demonstrated that optical stimulation of cholinergic neurons locally increased acetylcholine levels and increased wakefulness in mice. Surprisingly, the enhanced wakefulness caused by cholinergic stimulation was abolished by simultaneous reverse microdialysis of cholinergic receptor antagonists into BF. Thus, our data suggest that the wake-promoting effect of cholinergic stimulation requires local release of acetylcholine in the basal forebrain and activation of cortically projecting, non-cholinergic neurons, including the GABAergic/PV neurons. Optogenetics is a revolutionary tool to assess the roles of particular groups of neurons in behavioral functions, such as control of sleep and wakefulness. However, the interpretation of optogenetic experiments requires knowledge of the effects of stimulation on local neurotransmitter levels and effects on neighboring neurons. Here, using a novel "opto-dialysis" probe to couple optogenetics and in vivo microdialysis, we report that optical stimulation of basal forebrain (BF) cholinergic neurons in mice increases local acetylcholine levels and wakefulness. Reverse microdialysis of cholinergic antagonists within BF prevents the wake-promoting effect. This important result challenges the prevailing dictum that BF cholinergic projections to cortex directly control wakefulness and illustrates the utility of "opto-dialysis" for dissecting the complex brain circuitry underlying behavior. Copyright © 2016 the authors 0270-6474/16/362058-11$15.00/0.

Cholinergic Neurons in the Basal Forebrain Promote Wakefulness by Actions on Neighboring Non-Cholinergic Neurons: An Opto-Dialysis Study

PubMed Central

Zant, Janneke C.; Kim, Tae; Prokai, Laszlo; Szarka, Szabolcs; McNally, James; McKenna, James T.; Shukla, Charu; Yang, Chun; Kalinchuk, Anna V.; McCarley, Robert W.; Brown, Ritchie E.

2016-01-01

Understanding the control of sleep–wake states by the basal forebrain (BF) poses a challenge due to the intermingled presence of cholinergic, GABAergic, and glutamatergic neurons. All three BF neuronal subtypes project to the cortex and are implicated in cortical arousal and sleep–wake control. Thus, nonspecific stimulation or inhibition studies do not reveal the roles of these different neuronal types. Recent studies using optogenetics have shown that “selective” stimulation of BF cholinergic neurons increases transitions between NREM sleep and wakefulness, implicating cholinergic projections to cortex in wake promotion. However, the interpretation of these optogenetic experiments is complicated by interactions that may occur within the BF. For instance, a recent in vitro study from our group found that cholinergic neurons strongly excite neighboring GABAergic neurons, including the subset of cortically projecting neurons, which contain the calcium-binding protein, parvalbumin (PV) (Yang et al., 2014). Thus, the wake-promoting effect of “selective” optogenetic stimulation of BF cholinergic neurons could be mediated by local excitation of GABA/PV or other non-cholinergic BF neurons. In this study, using a newly designed opto-dialysis probe to couple selective optical stimulation with simultaneous in vivo microdialysis, we demonstrated that optical stimulation of cholinergic neurons locally increased acetylcholine levels and increased wakefulness in mice. Surprisingly, the enhanced wakefulness caused by cholinergic stimulation was abolished by simultaneous reverse microdialysis of cholinergic receptor antagonists into BF. Thus, our data suggest that the wake-promoting effect of cholinergic stimulation requires local release of acetylcholine in the basal forebrain and activation of cortically projecting, non-cholinergic neurons, including the GABAergic/PV neurons. SIGNIFICANCE STATEMENT Optogenetics is a revolutionary tool to assess the roles of particular groups of neurons in behavioral functions, such as control of sleep and wakefulness. However, the interpretation of optogenetic experiments requires knowledge of the effects of stimulation on local neurotransmitter levels and effects on neighboring neurons. Here, using a novel “opto-dialysis” probe to couple optogenetics and in vivo microdialysis, we report that optical stimulation of basal forebrain (BF) cholinergic neurons in mice increases local acetylcholine levels and wakefulness. Reverse microdialysis of cholinergic antagonists within BF prevents the wake-promoting effect. This important result challenges the prevailing dictum that BF cholinergic projections to cortex directly control wakefulness and illustrates the utility of “opto-dialysis” for dissecting the complex brain circuitry underlying behavior. PMID:26865627

A review of microdialysis coupled to microchip electrophoresis for monitoring biological events

PubMed Central

Saylor, Rachel A.; Lunte, Susan M.

2015-01-01

Microdialysis is a powerful sampling technique that enables monitoring of dynamic processes in vitro and in vivo. The combination of microdialysis with chromatographic or electrophoretic methods yields along with selective detection methods yields a “separation-based sensor” capable of monitoring multiple analytes in near real time. Analysis of microdialysis samples requires techniques that are fast (<1 min), have low volume requirements (nL–pL), and, ideally, can be employed on-line. Microchip electrophoresis fulfills these requirements and also permits the possibility of integrating sample preparation and manipulation with detection strategies directly on-chip. Microdialysis coupled to microchip electrophoresis has been employed for monitoring biological events in vivo and in vitro. This review discusses technical considerations for coupling microdialysis sampling and microchip electrophoresis, including various interface designs, and current applications in the field. PMID:25637011

Neuromonitoring after major neurosurgical procedures.

PubMed

Messerer, M; Daniel, R T; Oddo, M

2012-07-01

Postoperative care of major neurosurgical procedures is aimed at the prevention, detection and treatment of secondary brain injury. This consists of a series of pathological events (i.e. brain edema and intracranial hypertension, cerebral hypoxia/ischemia, brain energy dysfunction, non-convulsive seizures) that occur early after the initial insult and surgical intervention and may add further burden to primary brain injury and thus impact functional recovery. Management of secondary brain injury requires specialized neuroscience intensive care units (ICU) and continuous advanced monitoring of brain physiology. Monitoring of intracranial pressure (ICP) is a mainstay of care and is recommended by international guidelines. However, ICP monitoring alone may be insufficient to detect all episodes of secondary brain insults. Additional invasive (i.e. brain tissue PO2, cerebral microdialysis, regional cerebral blood flow) and non-invasive (i.e. transcranial doppler, near-infrared spectroscopy, EEG) brain monitoring devices might complement ICP monitoring and help clinicians to target therapeutic interventions (e.g. management of cerebral perfusion pressure, blood transfusion, glucose control) to patient-specific pathophysiology. Several independent studies demonstrate such multimodal approach may optimize patient care after major neurosurgical procedures. The aim of this review is to evaluate some of the available monitoring systems and summarize recent important data showing the clinical utility of multimodal neuromonitoring for the management of main acute neurosurgical conditions, including traumatic brain injury, subarachnoid hemorrhage and stroke.

Pathophysiology and the Monitoring Methods for Cardiac Arrest Associated Brain Injury.

PubMed

Reis, Cesar; Akyol, Onat; Araujo, Camila; Huang, Lei; Enkhjargal, Budbazar; Malaguit, Jay; Gospodarev, Vadim; Zhang, John H

2017-01-11

Cardiac arrest (CA) is a well-known cause of global brain ischemia. After CA and subsequent loss of consciousness, oxygen tension starts to decline and leads to a series of cellular changes that will lead to cellular death, if not reversed immediately, with brain edema as a result. The electroencephalographic activity starts to change as well. Although increased intracranial pressure (ICP) is not a direct result of cardiac arrest, it can still occur due to hypoxic-ischemic encephalopathy induced changes in brain tissue, and is a measure of brain edema after CA and ischemic brain injury. In this review, we will discuss the pathophysiology of brain edema after CA, some available techniques, and methods to monitor brain oxygen, electroencephalography (EEG), ICP (intracranial pressure), and microdialysis on its measurement of cerebral metabolism and its usefulness both in clinical practice and possible basic science research in development. With this review, we hope to gain knowledge of the more personalized information about patient status and specifics of their brain injury, and thus facilitating the physicians' decision making in terms of which treatments to pursue.

The Effects of Peripheral and Central High Insulin on Brain Insulin Signaling and Amyloid-β in Young and Old APP/PS1 Mice

PubMed Central

Stanley, Molly; Macauley, Shannon L.; Caesar, Emily E.; Koscal, Lauren J.; Moritz, Will; Robinson, Grace O.; Roh, Joseph; Keyser, Jennifer; Jiang, Hong

2016-01-01

Hyperinsulinemia is a risk factor for late-onset Alzheimer's disease (AD). In vitro experiments describe potential connections between insulin, insulin signaling, and amyloid-β (Aβ), but in vivo experiments are needed to validate these relationships under physiological conditions. First, we performed hyperinsulinemic-euglycemic clamps with concurrent hippocampal microdialysis in young, awake, behaving APPswe/PS1dE9 transgenic mice. Both a postprandial and supraphysiological insulin clamp significantly increased interstitial fluid (ISF) and plasma Aβ compared with controls. We could detect no increase in brain, ISF, or CSF insulin or brain insulin signaling in response to peripheral hyperinsulinemia, despite detecting increased signaling in the muscle. Next, we delivered insulin directly into the hippocampus of young APP/PS1 mice via reverse microdialysis. Brain tissue insulin and insulin signaling was dose-dependently increased, but ISF Aβ was unchanged by central insulin administration. Finally, to determine whether peripheral and central high insulin has differential effects in the presence of significant amyloid pathology, we repeated these experiments in older APP/PS1 mice with significant amyloid plaque burden. Postprandial insulin clamps increased ISF and plasma Aβ, whereas direct delivery of insulin to the hippocampus significantly increased tissue insulin and insulin signaling, with no effect on Aβ in old mice. These results suggest that the brain is still responsive to insulin in the presence of amyloid pathology but increased insulin signaling does not acutely modulate Aβ in vivo before or after the onset of amyloid pathology. Peripheral hyperinsulinemia modestly increases ISF and plasma Aβ in young and old mice, independent of neuronal insulin signaling. SIGNIFICANCE STATEMENT The transportation of insulin from blood to brain is a saturable process relevant to understanding the link between hyperinsulinemia and AD. In vitro experiments have found direct connections between high insulin and extracellular Aβ, but these mechanisms presume that peripheral high insulin elevates brain insulin significantly. We found that physiological hyperinsulinemia in awake, behaving mice does not increase CNS insulin to an appreciable level yet modestly increases extracellular Aβ. We also found that the brain of aged APP/PS1 mice was not insulin resistant, contrary to the current state of the literature. These results further elucidate the relationship between insulin, the brain, and AD and its conflicting roles as both a risk factor and potential treatment. PMID:27852778

[C3(OH)2mim][BF4]-Au/Pt biosensor for glutamate sensing in vivo integrated with on-line microdialysis system.

PubMed

Yu, Yanyan; Liu, Xiaoqian; Jiang, Dawei; Sun, Qian; Zhou, Tianshu; Zhu, Min; Jin, Litong; Shi, Guoyue

2011-03-15

A new type of hydroxyl functionalized room temperature ionic liquid (RTIL), [C(3)(OH)(2)mim][BF(4)], was synthesized herein and a novel H(2)O(2) biosensor is fabricated with [C(3)(OH)(2)mim][BF(4)] as the substrate and electrodepositing bimetallic Au/Pt nanoparticles (NPs) onto the [C(3)(OH)(2)mim][BF(4)] film. The functionalization of RTIL with hydroxyl groups provided an appropriate environment for the preparation of more uniform and smaller Au/Pt NPs with the diameter of 2.5 nm±0.2 nm. Immobilized with glutamate oxidase (GlutaOx), the resulting GlutaOx-[C(3)(OH)(2)mim][BF(4)]-Au/Pt-Nafion biosensor displayed excellent electrocatalytic response to glutamate at a potential of -200 mV. An effective on-line microdialysis system, which was powered by a microdialysis pump, was set up and used for the detection of glutamate successively in the striatum of rats. The glutamate biosensor in on-line microdialysis system showed good linear range from 0.5 μM to 20.0 μM with the detection limit of 0.17 μM (S/N=3). The basal level of glutamate in the striatum of anaesthetic rats was calculated to be 3.01±0.67 μM (n=3). The application of the GlutaOx-[C(3)(OH)(2)mim][BF(4)]-Au/Pt-Nafion electrode is further demonstrated for in vivo sensing of the variation of glutamate level in the striatum when rats received intraperitoneal (i.p.) injection of 100 mM KCl and brain electrical stimulation of the subthalamic nucleus area (STN). Both of the two kinds of stimulation resulted in an increase in the extracellular concentration of glutamate. This method has proved to be sensitive and reproducible, which enables its promising application in physiology and pathology. Copyright © 2010 Elsevier B.V. All rights reserved.

Coupling Microdialysis Sampling to Microchip Electrophoresis in a Reversibly Sealed Device

PubMed Central

Mecker, Laura C.; Martin, R. Scott

2007-01-01

In this paper, we describe the fabrication and characterization of a reversibly sealed microchip device that is used to couple microdialysis sampling to microchip electrophoresis. The ability to interface microdialysis sampling and microchip electrophoresis in a device that is amenable to reversible sealing is advantageous from a repeated use standpoint. Commercially available tubing coming from the microdialysis probe is directly inserted into the chip and flow from the probe is interfaced to the electrophoresis portion of the device through integrated pneumatic valves. Fluorescence detection was used to characterize the poly(dimethylsiloxane)-based device in terms of injection reproducibility. It was found that the entire system (microdialysis probe and microchip device) has a concentration response lag time of 170 sec. Microdialysis sampling followed by an electrophoretic separation of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide was also demonstrated. PMID:18836517

Metabolic changes in rat striatum following convulsive seizures.

PubMed

Darbin, Olivier; Risso, Jean Jacque; Carre, Emily; Lonjon, Michel; Naritoku, Dean K

2005-07-19

Generalized convulsive seizures increase glucose utilization within the brain but their impact on metabolism is not well known. The striatum receives excitatory input from widespread sources in the brain and could potentially reflect energy depletion in the brain resulting from generalized seizures. We utilized multiprobe microdialysis in freely moving rats subjected to maximal electroshock to simultaneously measure glucose, lactate, and pyruvate levels in the interstitial space within striatum and in peripheral subcutaneous tissue. A brief convulsive seizure was associated with marked changes in striatal and peripheral metabolism during the post-ictal state that lasted up to 1 h. There were significant central and peripheral elevations of glucose, pyruvate, and lactate, reflecting increased glucose metabolism. Interestingly, the lactate-to-pyruvate ratio increased significantly in the periphery but remained unchanged in the striatum. Thus, there appears to be brain mechanisms that maintain adequate energy sources and prevent anaerobic shift during the post-ictal state.

P-glycoprotein Inhibition Increases the Brain Distribution and Antidepressant-Like Activity of Escitalopram in Rodents

PubMed Central

O'Brien, Fionn E; O'Connor, Richard M; Clarke, Gerard; Dinan, Timothy G; Griffin, Brendan T; Cryan, John F

2013-01-01

Despite the clinical prevalence of the antidepressant escitalopram, over 30% of escitalopram-treated patients fail to respond to treatment. Recent gene association studies have highlighted a potential link between the drug efflux transporter P-glycoprotein (P-gp) and response to escitalopram. The present studies investigated pharmacokinetic and pharmacodynamic interactions between P-gp and escitalopram. In vitro bidirectional transport studies revealed that escitalopram is a transported substrate of human P-gp. Microdialysis-based pharmacokinetic studies demonstrated that administration of the P-gp inhibitor cyclosporin A resulted in increased brain levels of escitalopram without altering plasma escitalopram levels in the rat, thereby showing that P-gp restricts escitalopram transport across the blood–brain barrier (BBB) in vivo. The tail suspension test (TST) was carried out to elucidate the pharmacodynamic impact of P-gp inhibition on escitalopram effect in a mouse model of antidepressant activity. Pre-treatment with the P-gp inhibitor verapamil enhanced the response to escitalopram in the TST. Taken together, these data indicate that P-gp may restrict the BBB transport of escitalopram in humans, potentially resulting in subtherapeutic brain concentrations in certain patients. Moreover, by verifying that increasing escitalopram delivery to the brain by P-gp inhibition results in enhanced antidepressant-like activity, we suggest that adjunctive treatment with a P-gp inhibitor may represent a beneficial approach to augment escitalopram therapy in depression. PMID:23670590

In Vivo Microdialysis for Dynamic Monitoring of the Effectiveness of Nano-liposomes as Vehicles for Topical Psoralen Application.

PubMed

Zhang, Hongyu; Zhang, Kai; Li, Zhe; Zhao, Jihui; Zhang, Yongtai; Feng, Nianping

2017-01-01

In this study, the skin permeation of liposomes containing psoralen was investigated by in vivo skin microdialysis. Psoralen-loaded nano-sized liposomes were prepared with a mean size of 117.5 nm and a polydispersity index of 0.21, indicating the uniform dispersion of phosphatidylcholine vesicles in the liposomal solution. Based on in vivo microdialysis experiments, the drug concentration in local deep skin of rat increased rapidly and reached a peak concentration (C max ) of 319.35±23.72 µg/mL at 180 min, and decreased slowly thereafter. The local area under the concentration-time curve (AUC) 0-t was 3.81-fold higher than the compared aqueous suspension. The in vivo systemic pharmacokinetics were in agreement with the microdialysis results, in view of the C max and AUC 0-t from liposomal group were both significantly higher (p<0.05) than the compared group. Liposome-associated transdermal psoralen delivery was significantly more effective than delivery via an aqueous suspension. The enhanced skin permeability may be associated with improved skin hydration, lipid exchange and fusion with the stratum corneum (SC), and changes in SC structure, promoting drug permeation into deep skin. After 10 h of treatment with the perfusate, the microstructure of the microdialysis probe exhibited no obvious differences with control probes. The skin surface and the tissue around the probe showed no swelling or inflammation. These findings indicated that liposomes effectively enhanced the skin deposition of psoralen and showed good biocompatibility with skin tissues; additionally, ethanol at a low concentration in ringer's solution is an alternative perfusate for in vivo skin microdialysis studies.

Neuroenergetic Response to Prolonged Cerebral Glucose Depletion after Severe Brain Injury and the Role of Lactate.

PubMed

Patet, Camille; Quintard, Hervé; Suys, Tamarah; Bloch, Jocelyne; Daniel, Roy T; Pellerin, Luc; Magistretti, Pierre J; Oddo, Mauro

2015-10-15

Lactate may represent a supplemental fuel for the brain. We examined cerebral lactate metabolism during prolonged brain glucose depletion (GD) in acute brain injury (ABI) patients monitored with cerebral microdialysis (CMD). Sixty episodes of GD (defined as spontaneous decreases of CMD glucose from normal to low [<1.0 mmol/L] for at least 2 h) were identified among 26 patients. During GD, we found a significant increase of CMD lactate (from 4 ± 2.3 to 5.4 ± 2.9 mmol/L), pyruvate (126.9 ± 65.1 to 172.3 ± 74.1 μmol/L), and lactate/pyruvate ratio (LPR; 27 ± 6 to 35 ± 9; all, p < 0.005), while brain oxygen and blood lactate remained normal. Dynamics of lactate and glucose supply during GD were further studied by analyzing the relationships between blood and CMD samples. There was a strong correlation between blood and brain lactate when LPR was normal (r = 0.56; p < 0.0001), while an inverse correlation (r = -0.11; p = 0.04) was observed at elevated LPR >25. The correlation between blood and brain glucose also decreased from r = 0.62 to r = 0.45. These findings in ABI patients suggest increased cerebral lactate delivery in the absence of brain hypoxia when glucose availability is limited and support the concept that lactate acts as alternative fuel.

Ultrasonic microdialysis coupled with capillary electrophoresis electrochemiluminescence study the interaction between trimetazidine dihydrochloride and human serum albumin.

PubMed

Sun, Shuangjiao; Long, Chanjuan; Tao, Chunyao; Meng, Sa; Deng, Biyang

2014-12-03

The paper describes a homemade ultrasonic microdialysis device coupled with capillary electrophoresis electrochemiluminescence (CE-ECL) for studying the interaction between human serum albumin (HSA) and trimetazidine dihydrochloride (TMZ). The time required for equilibrium by ultrasonic microdialysis was 45min, which was far less than that by traditional dialysis (240min). It took 80min to achieve the required combination equilibrium by normal incubation and only 20min by ultrasonic. Compared with traditional dialysis, the use of ultrasonic microdialysis simplified experimental procedures, shortened experimental time and saved consumption of sample. A simple, sensitive and selective determination of TMZ was developed using CE-ECL and the parameters that affected ECL intensity were optimized. Under the optimized conditions, the linear range of TMZ was from 0.075 to 80μmol/L (r(2)=0.9974). The detection limit was 26nmol/L with RSD of 2.8%. The number of binding sites and binding constant were 1.54 and 15.17L/mol, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Use of rapid sampling microdialysis for intraoperative monitoring of bowel ischemia.

PubMed

Deeba, S; Corcoles, E P; Hanna, G B; Hanna, B G; Pareskevas, P; Aziz, O; Boutelle, M G; Darzi, A

2008-09-01

Intestinal ischemia is a major cause of anastomotic leak and death and remains a clinical challenge as the physician relies on several nonspecific signs, biologic markers, and radiologic studies to make the diagnosis. This study used rapid sampling online microdialysis to evaluate the biochemical changes occurring in a segment of human bowel during and after resection, and assessed for the feasibility and reproducibility of this technique in monitoring intestinal ischemia. A custom made, rapid sampling online microdialysis analyzer was used to monitor the changes in the bowel wall of specimens being resected intraoperatively. Two patients were recruited for the pilot study to optimize the analyzer and seven patients undergoing colonic resections were recruited for the data collection and analysis. The concentration of glucose in the extracellular bowel wall fluid decreased transiently after division of individual feeding arteries followed by a rebound increase in the concentration back to baseline concentrations. After completion of resection, glucose concentrations continued to decrease while lactate concentrations increased constantly. Rapid sampling microdialysis was feasible in the clinical environment. These results suggest that tissue responds to ischemic insult by mobilizing glucose stores which later decrease again, whereas lactate concentrations constantly increased.

IN VIVO MEASUREMENT OF PHENYLGLUCUCURONIDE IN RAINBOW TROUT BY ON-LINE INJECTION MICRODIALYSIS

EPA Science Inventory

Phenylglucuronide (PG) was measured in vivo in arterial blood of rainbow trout using on-line injection microdialysis. A microdialysis probe was surgically implanted in the dorsal aorta of spinally-transected trout. The trout were dosed continuously with PG for 24 h using a ventra...

Microdialysis as a New Technique for Extracting Phenolic Compounds from Extra Virgin Olive Oil.

PubMed

Bazzu, Gianfranco; Molinu, Maria Giovanna; Dore, Antonio; Serra, Pier Andrea

2017-03-01

The amount and composition of the phenolic components play a major role in determining the quality of olive oil. The traditional liquid-liquid extraction (LLE) method requires a time-consuming sample preparation to obtain the "phenolic profile" of extra virgin olive oil (EVOO). This study aimed to develop a microdialysis extraction (MDE) as an alternative to the LLE method to evaluate the phenolic components of EVOO. To this purpose, a microdialysis device and dialysis procedure were developed. "Dynamic-oil" microdialysis was performed using an extracting solution (80:20 methanol/water) flow rate of 2 μL min -1 and a constant EVOO stream of 4 μL min -1 . The results indicated a strong positive correlation between MDE and the LLE method, providing a very similar phenolic profile obtained with traditional LLE. In conclusion, the MDE approach, easier and quicker in comparison to LLE, provided a reliable procedure to determine the phenolic components used as a marker of the quality and traceability of EVOO.

Lactate shuttling and lactate use as fuel after traumatic brain injury: metabolic considerations

PubMed Central

Dienel, Gerald A

2014-01-01

Lactate is proposed to be generated by astrocytes during glutamatergic neurotransmission and shuttled to neurons as ‘preferred' oxidative fuel. However, a large body of evidence demonstrates that metabolic changes during activation of living brain disprove essential components of the astrocyte–neuron lactate shuttle model. For example, some glutamate is oxidized to generate ATP after its uptake into astrocytes and neuronal glucose phosphorylation rises during activation and provides pyruvate for oxidation. Extension of the notion that lactate is a preferential fuel into the traumatic brain injury (TBI) field has important clinical implications, and the concept must, therefore, be carefully evaluated before implementation into patient care. Microdialysis studies in TBI patients demonstrate that lactate and pyruvate levels and lactate/pyruvate ratios, along with other data, have important diagnostic value to distinguish between ischemia and mitochondrial dysfunction. Results show that lactate release from human brain to blood predominates over its uptake after TBI, and strong evidence for lactate metabolism is lacking; mitochondrial dysfunction may inhibit lactate oxidation. Claims that exogenous lactate infusion is energetically beneficial for TBI patients are not based on metabolic assays and data are incorrectly interpreted. PMID:25204393

A Food and Drug Administration-approved asthma therapeutic agent impacts amyloid β in the brain in a transgenic model of Alzheimer disease.

PubMed

Hori, Yukiko; Takeda, Shuko; Cho, Hansang; Wegmann, Susanne; Shoup, Timothy M; Takahashi, Kazue; Irimia, Daniel; Elmaleh, David R; Hyman, Bradley T; Hudry, Eloise

2015-01-23

Interfering with the assembly of Amyloid β (Aβ) peptides from monomer to oligomeric species and fibrils or promoting their clearance from the brain are targets of anti-Aβ-directed therapies in Alzheimer disease. Here we demonstrate that cromolyn sodium (disodium cromoglycate), a Food and Drug Administration-approved drug already in use for the treatment of asthma, efficiently inhibits the aggregation of Aβ monomers into higher-order oligomers and fibrils in vitro without affecting Aβ production. In vivo, the levels of soluble Aβ are decreased by over 50% after only 1 week of daily intraperitoneally administered cromolyn sodium. Additional in vivo microdialysis studies also show that this compound decreases the half-life of soluble Aβ in the brain. These data suggest a clear effect of a peripherally administered, Food and Drug Administration-approved medication on Aβ economy, supporting further investigation of the potential long-term efficacy of cromolyn sodium in Alzheimer disease. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Increased brain and plasma oxytocin after nasal and peripheral administration in rats and mice.

PubMed

Neumann, Inga D; Maloumby, Rodrigue; Beiderbeck, Daniela I; Lukas, Michael; Landgraf, Rainer

2013-10-01

The possibility to improve socio-emotional behaviors in humans by intranasal administration of synthetic oxytocin (OXT) attracts increasing attention, but its uptake into the brain has never been demonstrated so far. Here we used simultaneous microdialysis in both the dorsal hippocampus and amygdala of rats and mice in combination with concomitant blood sampling from the jugular vein to study the dynamics of the neuropeptide in brain extracellular fluid and plasma after its nasal administration. OXT was found to be increased in microdialysates from both the hippocampus and amygdala with peak levels occurring 30-60min after nasal administration. Despite a similar temporal profile of OXT concentrations in plasma, peripheral OXT is unlikely to contribute to dialysate OXT as calculated from in vitro recovery data, indicating a central route of transport. Moreover, intraperitoneal administration of synthetic OXT in identical amounts caused rapid peak levels in brain dialysates and plasma during the first 30min after treatment and a subsequent return toward baseline. While the precise route(s) of central transport remain to be elucidated, our data provide the first evidence that nasally applied OXT indeed reaches behaviorally relevant brain areas, and this uptake is paralleled by changes in plasma OXT. Copyright © 2013 Elsevier Ltd. All rights reserved.

Brain CYP2B induction can decrease nicotine levels in the brain.

PubMed

Garcia, Kristine L P; Lê, Anh Dzung; Tyndale, Rachel F

2017-09-01

Nicotine can be metabolized by the enzyme CYP2B; brain CYP2B is higher in rats and monkeys treated with nicotine, and in human smokers. A 7-day nicotine treatment increased CYP2B expression in rat brain but not liver, and decreased the behavioral response and brain levels (ex vivo) to the CYP2B substrate propofol. However, the effect of CYP2B induction on the time course and levels of circulating brain nicotine in vivo has not been demonstrated. Using brain microdialysis, nicotine levels following a subcutaneous nicotine injection were measured on day one and after a 7-day nicotine treatment. There was a significant time x treatment interaction (p = 0.01); peak nicotine levels (15-45 minutes post-injection) were lower after treatment (p = 0.04) consistent with CYP2B induction. Following a two-week washout period, brain nicotine levels increased to day one levels (p = 0.02), consistent with brain CYP2B levels returning to baseline. Brain pretreatment of the CYP2B inhibitor, C8-xanthate, increased brain nicotine levels acutely and after 7-day nicotine treatment, indicating the alterations in brain nicotine levels were due to changes in brain CYP2B activity. Plasma nicotine levels were not altered for any time or treatment sampled, confirming no effect on peripheral nicotine metabolism. These results demonstrate that chronic nicotine, by increasing brain CYP2B activity, reduces brain nicotine levels, which could alter nicotine's reinforcing effects. Higher brain CYP2B levels in smokers could lower brain nicotine levels; as this induction would occur following continued nicotine exposure it could increase withdrawal symptoms and contribute to sustaining smoking behavior. © 2016 Society for the Study of Addiction.

In vivo monitoring of multiple trace metals in the brain extracellular fluid of anesthetized rats by microdialysis-membrane desalter-ICPMS.

PubMed

Chung, Y T; Ling, Y C; Yang, C S; Sun, Y C; Lee, P L; Lin, C Y; Hong, C C; Yang, M H

2007-12-01

We have developed an on-line analytical system involving microdialysis (MD) sampling, a carbohydrate membrane desalter (CMD), and an inductively coupled plasma mass spectrometer (ICPMS) system for the simultaneous determination of multiple trace metals in the extracellular fluid (ECF) in the brains of anesthetized rats. The microdialysate that perfused from the animal at a flow rate of 0.5 microL/min was on-line transferred to the CMD to remove the high-sodium matrix, followed by ICPMS measurement. The role of the CMD in this on-line system was investigated in detail. With prior addition of EDTA to the microdialysate to form anionic complexes of the metal analytes and the use of NH4Cl as a regenerant to exchange Na(+) with NH4(+) ions, both quantitative recovery of the trace metal analytes and quantitative removal of the sodium matrix could be achieved. Two experimental modes of the monitoring system were constructed. For those metals (e.g., Cu, Zn, and Mn) that existed at (sub)nanogram-per-milliliter concentrations in the microdialysate, the temporal resolution was 10 min when using a 10 microL loop for sample collection, followed by CMD and ICPMS; for those elements (e.g., Ca and Mg) that existed at microgram-per-milliliter levels (or greater), near-real-time analysis was possible because the microdialysate could be led, bypassing the sample loop, directly to the CMD for desalting without any time delay. Further improvement of the temporal resolution for the low-concentration elements was not possible without decreasing the detection limits of mass detection. Among the eight trace metals tested using this on-line system, the method detection limits for Cu, Zn, Mn, Co, Ni, and Pb reached subnanogram-per-milliliter levels; for electrolyte species such as Ca and Mg, the detection limits were in the range of 50-100 ng/mL. Analytical accuracy, expressed as spike recovery, was 100% +/- 15% for all of the elements tested. We demonstrate the applicability of the proposed system through the successful measurement of the basal values of Ca, Mg, Cu, Zn, and Mn in the ECF of a living rat brain and through in vivo monitoring of the concentration profiles of Mn and Pt in the ECF after the injection of drugs (MnCl2 and cisplatin) into the rats. This microdialysis system is the first to offer real-time, in vivo monitoring of trace elements such as Ca and Mg.

What’s New in Traumatic Brain Injury: Update on Tracking, Monitoring and Treatment

PubMed Central

Reis, Cesar; Wang, Yuechun; Akyol, Onat; Ho, Wing Mann; Applegate II, Richard; Stier, Gary; Martin, Robert; Zhang, John H.

2015-01-01

Traumatic brain injury (TBI), defined as an alteration in brain functions caused by an external force, is responsible for high morbidity and mortality around the world. It is important to identify and treat TBI victims as early as possible. Tracking and monitoring TBI with neuroimaging technologies, including functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), positron emission tomography (PET), and high definition fiber tracking (HDFT) show increasing sensitivity and specificity. Classical electrophysiological monitoring, together with newly established brain-on-chip, cerebral microdialysis techniques, both benefit TBI. First generation molecular biomarkers, based on genomic and proteomic changes following TBI, have proven effective and economical. It is conceivable that TBI-specific biomarkers will be developed with the combination of systems biology and bioinformation strategies. Advances in treatment of TBI include stem cell-based and nanotechnology-based therapy, physical and pharmaceutical interventions and also new use in TBI for approved drugs which all present favorable promise in preventing and reversing TBI. PMID:26016501

Stimuli and consequences of dendritic release of oxytocin within the brain.

PubMed

Neumann, I D

2007-11-01

The brain oxytocin system has served as a distinguished model system in neuroendocrinology to study detailed mechanisms of intracerebral release, in particular of somatodendritic release, and its behavioural and neuroendocrine consequences. It has been shown that oxytocin is released within various brain regions, but evidence for dendritic release is limited to the main sites of oxytocin synthesis, i.e. the hypothalamic SON (supraoptic nucleus) and PVN (paraventricular nucleus). In the present paper, stimuli of dendritic release of oxytocin and the related neuropeptide vasopressin are discussed, including parturition and suckling, i.e. the period of a highly activated brain oxytocin system. Also, exposure to various pharmacological, psychological or physical stressors triggers dendritic oxytocin release, as monitored by intracerebral microdialysis within the SON and PVN during ongoing behavioural testing. So far, dendritic release of the neuropeptide has only been demonstrated within the hypothalamus, but intracerebral oxytocin release has also been found within the central amygdala and the septum in response to various stimuli including stressor exposure. Such a locally released oxytocin modulates physiological and behavioural reproductive functions, emotionality and hormonal stress responses, as it exerts, for example, pro-social, anxiolytic and antistress actions within restricted brain regions. These discoveries make oxytocin a promising neuromodulator of the brain for psychotherapeutic intervention and treatment of numerous psychiatric illnesses, for example, anxiety-related diseases, social phobia, autism and postpartum depression.

The 5-HT1A/1B-receptor agonist eltoprazine increases both catecholamine release in the prefrontal cortex and dopamine release in the nucleus accumbens and decreases motivation for reward and "waiting" impulsivity, but increases "stopping" impulsivity.

PubMed

Korte, S Mechiel; Prins, Jolanda; Van den Bergh, Filip S; Oosting, Ronald S; Dupree, Rudy; Korte-Bouws, Gerdien A H; Westphal, Koen G C; Olivier, Berend; Denys, Damiaan A; Garland, Alexis; Güntürkün, Onur

2017-01-05

The 5-HT 1A/1B -receptor agonist eltoprazine has a behavioral drug signature that resembles that of a variety of psychostimulant drugs, despite the differences in receptor binding profile. These psychostimulants are effective in treating impulsivity disorders, most likely because they increase norepinephrine (NE) and dopamine (DA) levels in the prefrontal cortex. Both amphetamine and methylphenidate, however, also increase dopamine levels in the nucleus accumbens (NAc), which has a significant role in motivation, pleasure, and reward. How eltoprazine affects monoamine release in the medial prefrontal cortex (mPFC), the orbitofrontal cortex (OFC), and the NAc is unknown. It is also unknown whether eltoprazine affects different forms of impulsivity and brain reward mechanisms. Therefore, in the present study, we investigate the effects of eltoprazine in rats in the following sequence: 1) the activity of the monoaminergic systems using in vivo microdialysis, 2) motivation for reward measured using the intracranial self-stimulation (ICSS) procedure, and finally, 3) "waiting" impulsivity in the delay-aversion task, and the "stopping" impulsivity in the stop-signal task. The microdialysis studies clearly showed that eltoprazine increased DA and NE release in both the mPFC and OFC, but only increased DA concentration in the NAc. In contrast, eltoprazine decreased 5-HT release in the mPFC and NAc (undetectable in the OFC). Remarkably, eltoprazine decreased impulsive choice, but increased impulsive action. Furthermore, brain stimulation was less rewarding following eltoprazine treatment. These results further support the long-standing hypothesis that "waiting" and "stopping" impulsivity are regulated by distinct neural circuits, because 5-HT 1A/1B -receptor activation decreases impulsive choice, but increases impulsive action. Copyright © 2016 Elsevier B.V. All rights reserved.

Dermal microdialysis of inflammatory markers induced by aliphatic hydrocarbons in rats

PubMed Central

Patlolla, Ram R.; Mallampati, Ramya; Fulzele, Suniket V.; Babu, R. Jayachandra; Singh, Mandip

2010-01-01

In the present study we made an attempt to understand the skin irritation cascade of selected aliphatic hydrocarbons using microdialysis technique. Microdialysis probes were inserted into dermis in the dorsal skin of hairless rats. After 2 h of probes insertion, occlusive dermal exposure (2 h) was carried out with 230 μl of nonane, dodecane and tetradecane, using Hill top chambers®. Inflammatory biomarkers such as substance P (SP), α-melanocyte stimulating hormone (α-MSH) Interleukin 6 (IL-6) and prostaglandin E2 (PGE2) were analyzed in the dialysis samples by enzyme immunoassay (EIA). SP, α-MSH and IL6 were released in significant amounts following the dermal exposure of nonane and dodecane, whereas tetradecane did not induce any of these markers in significant amounts compared to control. Nonane increased the PGE2 levels in significant amounts within 2 h of chemical exposure compared to dodecane and tetradecane. IL-6 response was found to be slow and 2–3-fold increase in IL-6 levels was observed after 5 h following nonane and dodecane application. The magnitude of skin irritation exerted by all three chemicals was in the order of nonane ≥ dodecane ≥ tetradecane. The results demonstrate that microdialysis can be used to measure the inflammatory biomarkers in the skin irritation studies and irritation response of chemicals was quantifiable by this method. In conclusion, microdialysis was found to be an excellent tool to measure several inflammatory biomarkers as a function of time after dermal exposures with irritant chemicals. PMID:19152832

Haloperidol impairs auditory filial imprinting and modulates monoaminergic neurotransmission in an imprinting-relevant forebrain area of the domestic chick.

PubMed

Gruss, M; Bock, J; Braun, K

2003-11-01

In vivo microdialysis and behavioural studies in the domestic chick have shown that glutamatergic as well as monoaminergic neurotransmission in the medio-rostral neostriatum/hyperstriatum ventrale (MNH) is altered after auditory filial imprinting. In the present study, using pharmaco-behavioural and in vivo microdialysis approaches, the role of dopaminergic neurotransmission in this juvenile learning event was further evaluated. The results revealed that: (i) the systemic application of the potent dopamine receptor antagonist haloperidol (7.5 mg/kg) strongly impairs auditory filial imprinting; (ii) systemic haloperidol induces a tetrodotoxin-sensitive increase of extracellular levels of the dopamine metabolite, homovanillic acid, in the MNH, whereas the levels of glutamate, taurine and the serotonin metabolite, 5-hydroxyindole-3-acetic acid, remain unchanged; (iii) haloperidol (0.01, 0.1, 1 mm) infused locally into the MNH increases glutamate, taurine and 5- hydroxyindole-3-acetic acid levels in a dose-dependent manner, whereas homovanillic acid levels remain unchanged; (iv) systemic haloperidol infusion reinforces the N-methyl-d-aspartate receptor-mediated inhibitory modulation of the dopaminergic neurotransmission within the MNH. These results indicate that the modulation of dopaminergic function and its interaction with other neurotransmitter systems in a higher associative forebrain region of the juvenile avian brain displays similar neurochemical characteristics as the adult mammalian prefrontal cortex. Furthermore, we were able to show that the pharmacological manipulation of monoaminergic regulatory mechanisms interferes with learning and memory formation, events which in a similar fashion might occur in young or adult mammals.

Reduced brain/serum glucose ratios predict cerebral metabolic distress and mortality after severe brain injury.

PubMed

Kurtz, Pedro; Claassen, Jan; Schmidt, J Michael; Helbok, Raimund; Hanafy, Khalid A; Presciutti, Mary; Lantigua, Hector; Connolly, E Sander; Lee, Kiwon; Badjatia, Neeraj; Mayer, Stephan A

2013-12-01

The brain is dependent on glucose to meet its energy demands. We sought to evaluate the potential importance of impaired glucose transport by assessing the relationship between brain/serum glucose ratios, cerebral metabolic distress, and mortality after severe brain injury. We studied 46 consecutive comatose patients with subarachnoid or intracerebral hemorrhage, traumatic brain injury, or cardiac arrest who underwent cerebral microdialysis and intracranial pressure monitoring. Continuous insulin infusion was used to maintain target serum glucose levels of 80-120 mg/dL (4.4-6.7 mmol/L). General linear models of logistic function utilizing generalized estimating equations were used to relate predictors of cerebral metabolic distress (defined as a lactate/pyruvate ratio [LPR] ≥ 40) and mortality. A total of 5,187 neuromonitoring hours over 300 days were analyzed. Mean serum glucose was 133 mg/dL (7.4 mmol/L). The median brain/serum glucose ratio, calculated hourly, was substantially lower (0.12) than the expected normal ratio of 0.40 (brain 2.0 and serum 5.0 mmol/L). In addition to low cerebral perfusion pressure (P = 0.05) and baseline Glasgow Coma Scale score (P < 0.0001), brain/serum glucose ratios below the median of 0.12 were independently associated with an increased risk of metabolic distress (adjusted OR = 1.4 [1.2-1.7], P < 0.001). Low brain/serum glucose ratios were also independently associated with in-hospital mortality (adjusted OR = 6.7 [1.2-38.9], P < 0.03) in addition to Glasgow Coma Scale scores (P = 0.029). Reduced brain/serum glucose ratios, consistent with impaired glucose transport across the blood brain barrier, are associated with cerebral metabolic distress and increased mortality after severe brain injury.

Phasic Dopaminergic Signaling and the Presymptomatic Phase of Parkinson’s Disease

DTIC Science & Technology

2005-07-01

provides an ambient , steady- state level of extracellular dopamine, whereas phasic signaling results in a transient increase (i.e., a short-lived...certain ambient extracellular level of dopamine is essential for movement to occur [116]. Phasic signaling involves synchronized high frequency firing of...microdialysis. A measurement of the ambient level of dopamine by microdialysis in animal studies shows that extracellular dopamine levels are normal

Comparison of microdialysis sampling perfusion fluid components on the foreign body reaction in rat subcutaneous tissue.

PubMed

Keeler, Geoffrey D; Durdik, Jeannine M; Stenken, Julie A

2014-06-16

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration. While these perfusion fluid additives are commonly used during microdialysis sampling, the tissue response to the loss of these compounds across the membrane is poorly understood. Tissue reactions to implanted microdialysis sampling probes containing different microdialysis perfusion fluids were compared over a 7-day time period in rats. The base perfusion fluid was Ringer's solution supplemented with either bovine serum albumin (BSA), rat serum albumin (RSA), Dextran-70, or Dextran-500. A significant inflammatory response to Dextran-70 was observed. No differences in the tissue response between BSA and RSA were observed. Among these agents, the BSA, RSA, and Dextran-500 produced a significantly reduced inflammatory response compared to the Dextran-70. This work demonstrates that use of Dextran-70 in microdialysis sampling perfusion fluids should be eliminated and replaced with Dextran-500 or other alternatives. Copyright © 2013 Elsevier B.V. All rights reserved.

Brain Histamine Is Crucial for Selective Serotonin Reuptake Inhibitors‘ Behavioral and Neurochemical Effects

PubMed Central

Munari, Leonardo; Provensi, Gustavo; Passani, Maria Beatrice; Galeotti, Nicoletta; Cassano, Tommaso; Benetti, Fernando; Corradetti, Renato

2015-01-01

Backgound: The neurobiological changes underlying depression resistant to treatments remain poorly understood, and failure to respond to selective serotonin reuptake inhibitors may result from abnormalities of neurotransmitter systems that excite serotonergic neurons, such as histamine. Methods: Using behavioral (tail suspension test) and neurochemical (in vivo microdialysis, Western-blot analysis) approaches, here we report that antidepressant responses to selective serotonin reuptake inhibitors (citalopram or paroxetine) are abolished in mice unable to synthesize histamine due to either targeted disruption of histidine decarboxylase gene (HDC-/-) or injection of alpha-fluoromethylhistidine, a suicide inhibitor of this enzyme. Results: In the tail suspension test, all classes of antidepressants tested reduced the immobility time of controls. Systemic reboxetine or imipramine reduced the immobility time of histamine-deprived mice as well, whereas selective serotonin reuptake inhibitors did not even though their serotonergic system is functional. In in vivo microdialysis experiments, citalopram significantly increased histamine extraneuronal levels in the cortex of freely moving mice, and methysergide, a serotonin 5-HT1/5-HT2 receptor antagonist, abolished this effect, thus suggesting the involvement of endogenous serotonin. CREB phosphorylation, which is implicated in the molecular mechanisms of antidepressant treatment, was abolished in histamine-deficient mice treated with citalopram. The CREB pathway is not impaired in HDC-/- mice, as administration of 8-bromoadenosine 3’, 5’-cyclic monophosphate increased CREB phosphorylation, and in the tail suspension test it significantly reduced the time spent immobile by mice of both genotypes. Conclusions: Our results demonstrate that selective serotonin reuptake inhibitors selectively require the integrity of the brain histamine system to exert their preclinical responses. PMID:25899065

Serotonergic, Brain Volume and Attentional Correlates of Trait Anxiety in Primates

PubMed Central

Mikheenko, Yevheniia; Shiba, Yoshiro; Sawiak, Stephen; Braesicke, Katrin; Cockcroft, Gemma; Clarke, Hannah; Roberts, Angela C

2015-01-01

Trait anxiety is a risk factor for the development and maintenance of affective disorders, and insights into the underlying brain mechanisms are vital for improving treatment and prevention strategies. Translational studies in non-human primates, where targeted neurochemical and genetic manipulations can be made, are critical in view of their close neuroanatomical similarity to humans in brain regions implicated in trait anxiety. Thus, we characterised the serotonergic and regional brain volume correlates of trait-like anxiety in the marmoset monkey. Low- and high-anxious animals were identified by behavioral responses to a human intruder (HI) that are known to be sensitive to anxiolytic drug treatment. Extracellular serotonin levels within the amygdala were measured with in vivo microdialysis, at baseline and in response to challenge with the selective serotonin reuptake inhibitor, citalopram. Regional brain volume was assessed by structural magnetic resonance imaging. Anxious individuals showed persistent, long-term fearful responses to both a HI and a model snake, alongside sustained attention (vigilance) to novel cues in a context associated with unpredictable threat. Neurally, high-anxious marmosets showed reduced amygdala serotonin levels, and smaller volumes in a closely connected prefrontal region, the dorsal anterior cingulate cortex. These findings highlight behavioral and neural similarities between trait-like anxiety in marmosets and humans, and set the stage for further investigation of the processes contributing to vulnerability and resilience to affective disorders. PMID:25586542

Preliminary evaluation of several disinfection/sterilization techniques for use with microdialysis probes.

PubMed

Huff, Jacquelyn K; Bresnahan, James F; Davies, Malonne I

2003-06-06

This study evaluated the suitability of some disinfection and sterilization methods for use with microdialysis probes. Disinfection or sterilization should minimize the tissue inflammatory reaction and improve the long-term health of rats on study and ensure the quality of data obtained by microdialysis sampling. Furthermore, the treatment should not negatively impact probe integrity or sampling performance. The techniques chosen for evaluation included two disinfection methods (70% ethanol and a commercial contact lens solution) and two sterilization methods (hydrogen peroxide plasma, and e-beam radiation). Linear microdialysis probes treated by these processes were compared to untreated probes removed from the manufacturer's packaging as if sterile (the control group). The probes were aseptically implanted in the livers of rats and monitored for 72 hours. The parameters chosen to evaluate probe performance were relative sample mass recovery and the relative in vivo extraction efficiency of the probe for caffeine. Post mortem bacterial counts and histopathology examination of liver tissue were also conducted. The probes remained intact and functional for the entire study period. The methods tested did not acutely alter the probes although hydrogen peroxide plasma and contact lens solution groups showed reduced extraction efficiencies. Minimal tissue damage was observed surrounding the probes and acute inflammatory reaction was mild to moderate. Low numbers of bacterial colonies from the implantation sites indicates that the health of animals in this study was not impaired. This was also true for the control group (untreated probe).

Pharmacokinetics of timolol in aqueous humor sampled by microdialysis after topical administration of thermosetting gels.

PubMed

Wei, Gang; Ding, Ping-Tian; Zheng, Jun-Min; Lu, Wei-Yue

2006-01-01

In order to develop a thermosetting gel-based formulation, the ocular pharmacokinetics of timolol was studied utilizing microdialysis sampling technique after topical administration. A linear microdialysis probe was characterized and implanted in the anterior chamber of a rabbit. Dialysate samples collected from the aqueous humor (AH) were directly injected into the HPLC system without any pre-treatment and no interference was observed in the blank sample. The measured in vitro recovery of the probe was 57.67%; however, the in vivo recovery significantly decreased to 16.78% when assessed by the retrodialysis method, which was used to calculate the timolol concentration in AH. Although in the initial 15 min the drug concentrations in AH were comparable to that of the timolol solution, increased Cmax and significantly improved ocular bioavailability were obtained for the gel. When sodium deoxycholate (DC) was incorporated in the gel as a penetration enhancer, a 2-fold increment in the ocular bioavailability was achieved with an increased Cmax and significantly suspended Tmax. The results demonstrated that microdialysis coupled to HPLC is a powerful tool to investigate the ocular pharmacokinetic, and hence facilitates the design of ophthalmic formulations. Copyright 2005 John Wiley & Sons, Ltd.

Urea clearance: a new technique based on microdialysis to assess liver blood flow studied in a pig model of ischemia/reperfusion.

PubMed

Farnebo, S; Winbladh, A; Zettersten, E K; Sandström, P; Gullstrand, P; Samuelsson, A; Theodorson, E; Sjöberg, F

2010-01-01

Delayed detection of ischemia is one of the most feared postoperative complications. Early detection of impaired blood flow and close monitoring of the organ-specific metabolic status may therefore be critical for the surgical outcome. Urea clearance is a new technique for continuous monitoring of alterations in blood flow and metabolic markers with acceptable temporal characteristics. We compare this new microdialysis technique with the established microdialysis ethanol technique to assess hepatic blood flow. Six pigs were used in a liver ischemia/reperfusion injury model. Microdialysis catheters were placed in liver segment IV and all circulation was stopped for 80 min, followed by reperfusion for 220 min. Urea and ethanol clearance was calculated from the dialysate and correlated with metabolic changes. A laser Doppler probe was used as reference of restoration of blood flow. Both urea and ethanol clearance reproducibly depicted changes in liver blood flow in relation to metabolic changes and laser Doppler measurements. The two techniques highly correlated both overall and during the reperfusion phase (r = 0.8) and the changes were paralleled by altered perfusion as recorded by laser Doppler. Copyright © 2010 S. Karger AG, Basel.

Targeted deletion of kynurenine 3-monooxygenase in mice: a new tool for studying kynurenine pathway metabolism in periphery and brain.

PubMed

Giorgini, Flaviano; Huang, Shao-Yi; Sathyasaikumar, Korrapati V; Notarangelo, Francesca M; Thomas, Marian A R; Tararina, Margarita; Wu, Hui-Qiu; Schwarcz, Robert; Muchowski, Paul J

2013-12-20

Kynurenine 3-monooxygenase (KMO), a pivotal enzyme in the kynurenine pathway (KP) of tryptophan degradation, has been suggested to play a major role in physiological and pathological events involving bioactive KP metabolites. To explore this role in greater detail, we generated mice with a targeted genetic disruption of Kmo and present here the first biochemical and neurochemical characterization of these mutant animals. Kmo(-/-) mice lacked KMO activity but showed no obvious abnormalities in the activity of four additional KP enzymes tested. As expected, Kmo(-/-) mice showed substantial reductions in the levels of its enzymatic product, 3-hydroxykynurenine, in liver, brain, and plasma. Compared with wild-type animals, the levels of the downstream metabolite quinolinic acid were also greatly decreased in liver and plasma of the mutant mice but surprisingly were only slightly reduced (by ∼20%) in the brain. The levels of three other KP metabolites: kynurenine, kynurenic acid, and anthranilic acid, were substantially, but differentially, elevated in the liver, brain, and plasma of Kmo(-/-) mice, whereas the liver and brain content of the major end product of the enzymatic cascade, NAD(+), did not differ between Kmo(-/-) and wild-type animals. When assessed by in vivo microdialysis, extracellular kynurenic acid levels were found to be significantly elevated in the brains of Kmo(-/-) mice. Taken together, these results provide further evidence that KMO plays a key regulatory role in the KP and indicate that Kmo(-/-) mice will be useful for studying tissue-specific functions of individual KP metabolites in health and disease.

Effect of ligustrazine on levels of amino acid neurotransmitters in rat striatum after cerebral ischemia-reperfusion injury.

PubMed

Han, Jin; Wan, Hai-Tong; Yang, Jie-Hong; Zhang, Yu-Yan; Ge, Li-Jun; Bie, Xiao-Dong

2014-01-01

This study aimed to evaluate the effect of ligustrazine on levels of amino acid transmitters in the extracellular fluid of striatum following cerebral ischemia/reperfusion (I/R) in male Sprague-Dawley rats. A microdialysis cannula guide was implanted into the right striatum. After recovery, animals underwent a sham operation or middle cerebral artery occlusion (MCAO). Those that developed cerebral ischemia after MCAO were randomized to receive propylene glycol salt water and ligustrazine respectively. Striatal fluid samples were collected from all animals at 15-min intervals after treatment and were subjected to HPLC analysis of aspartic acid, glutamic acid, taurine, and γ-amino butyric acid. Upon the last sample collection, animals were sacrificed and brain tissue specimens were collected for triphenyltetrazolium chloride staining and NeuN staining. Compared with the sham operation, MCAO induced significant neurological deficits and increased striatal concentrations of the four neurotransmitters assessed in a time-dependent manner (P < 0.01). Ligustrazine effectively attenuated the detrimental effects of MCAO on the brain. These observations suggest that ligustrazine as a novel cerebral infarction-protective agent may have potential clinical implications for I/R-related brain damage.

Exploring Thermoresponsive Affinity Agents to Enhance Microdialysis Sampling Efficiency of Proteins

NASA Astrophysics Data System (ADS)

Vasicek, Thaddeus

Affinity agents increase microdialysis protein relative recovery, yet they have not seen widespread use within the microdialysis community due to their additional instrumentation requirements and prohibitive cost. This dissertation describes new affinity agents for microdialysis that require no additional instrumentation to use, have nearly 100% particle recovery, are 7 times more cost efficient than alternatives, and have low specificity enabling their use for a wide variety of proteins. Initially gold nanoparticles were chosen as an affinity ligand support due to their high surface area/volume ratio and colloidal stability. Poly (N-isopropylacrylamide) was immobilized to the gold nanoparticles, which served to sterically stabilize the particles and to act as a generic, reversible protein capture agent. A method was developed to reproducibly vary and quantify poly (N-isopropylacrylamide) graft density from 0.09 to 0.40 ligands/nm2 on gold nanoparticles. During characterization of the polymer coated gold nanoparticles, irreversible particle agglomeration was observed at low polymer graft density in ionic solutions, which prevented further development as a protein capture agent. Poly (N-isopropylacrylamide) nanogels, which have low nonspecific adsorption, low interparticle attractive forces owing to the low curvature of the particle, and a low Hamaker constant, were synthesized to overcome the agglomeration problem. A generic protein affinity ligand cibacron blue, was immobilized to the nanogels, which enabled rapid determination of particle recovery. The perfusion of the nanogels through a microdialysis probe was optimized yielding 100% particle recovery using a combination of a syringe and peristaltic pump. The microdialysis collection efficiency of CCL2, a physiologically relevant cytokine, was increased 3-fold with addition of the nanogel to the microdialysis perfusion fluid. The reduction in instrumentation requirements, low cost, and low specificity obtained with the new affinity agents will lead to increased affinity agent use for microdiaylsis protein sampling.

Programmable carbon nanotube membrane-based transdermal nicotine delivery with microdialysis validation assay.

PubMed

Gulati, Gaurav Kumar; Chen, Tao; Hinds, Bruce Jackson

2017-01-01

To evaluate the performance of switchable carbon nanotubes (CNT) membrane devices for transdermal nicotine delivery, we have developed an in-vitro microdialysis method that allow us to detect variable transdermal fluxes of nicotine through CNT devices and can be applied directly to in-vivo studies. Microdialysis membranes were placed beneath the porcine skin and its nicotine levels increased 6-8 times when the CNT membrane on skin was turned from OFF to ON state by application of bias. Fluxes in the ON state were approximately 3 times that of commercial nicotine patches and switching times were less than two hours, thus suggesting the improved therapeutic potential of our device. Blue tooth enabled CNT devices that can be programmed by smartphone and coupled with remote counseling application for enhanced smoking cessation treatments. Copyright © 2016. Published by Elsevier Inc.

Interaction between LSD and dopamine D2/3 binding sites in pig brain.

PubMed

Minuzzi, Luciano; Nomikos, George G; Wade, Mark R; Jensen, Svend B; Olsen, Aage K; Cumming, Paul

2005-06-15

The psychoactive properties of the hallucinogen LSD have frequently been attributed to high affinity interactions with serotonin 5HT2 receptors in brain. Possible effects of LSD on dopamine D2/3 receptor availability have not previously been investigated in living brain. Therefore, we used PET to map the binding potential (pB) of [11C]raclopride in brain of three pigs, first in a baseline condition, and again at 1 and 4 h after administration of LSD (2.5 microg/kg, i.v.). There was a progressive treatment effect in striatum, where the pB was significantly reduced by 19% at 4 h after LSD administration. Concomitant maps of cerebral blood flow did not reveal significant changes in perfusion during this interval. Subsequent in vitro studies showed that LSD displaced [3H]raclopride (2 nM) from pig brain cryostat sections with an IC50 of 275 nM according to a one-site model. Fitting of a two-site model to the data suggested the presence of a component of the displacement curves with a subnanomolar IC50, comprising 20% of the total [3H]raclopride binding. In microdialysis experiments, LSD at similar and higher doses did not evoke changes in the interstitial concentration of dopamine or its acidic metabolites in rat striatum. Together, these results are consistent with a direct interaction between LSD and a portion of dopamine D2/3 receptors in pig brain, possibly contributing to the psychopharmacology of LSD. (c) 2005 Wiley-Liss, Inc.

Reliable glucose monitoring by ex-vivo blood microdialysis and infrared spectrometry for patients in critical care

NASA Astrophysics Data System (ADS)

Vahlsing, Thorsten; Delbeck, Sven; Budde, Janpeter; Ihrig, Dieter; Leonhardt, Steffen; Heise, H. Michael

2017-02-01

Blood glucose monitoring has been realised by biosensors in combination with micro-dialysis, using either subcutaneously or intravascularly implanted catheters. Another alternative is ex-vivo micro-dialysis of continuously sampled heparinized whole blood available from the patient even under critical care conditions. However, most devices suffer from inaccuracies due to variable recovery rates. Infrared spectrometry has been suggested for analyte quantification, since besides glucose other clinically relevant analytes can be simultaneously determined that are, e.g., important for intensive care patients. Perfusates with acetate and mannitol have been investigated as recovery markers (internal standards). In contrast to the previously used acetate, an almost linear dependency between mannitol loss and glucose recovery was observed for micro-dialysis of glucose spiked aqueous albumin solutions or porcine heparinized whole blood when testing flat membranes within a custom-made micro-dialysator. By this, a straightforward compensation of any dialysis recovery rate variation during patient monitoring is possible. The combination of microdialysis with infrared spectrometry provides a calibration-free assay for accurate continuous glucose monitoring, as reference spectra of dialysate components can be a-priori allocated.

Constructing Inexpensive, Flexible, and Versatile Microdialysis Probes in an Undergraduate Microdialysis Research Lab

PubMed Central

Steffes, Sally; Sandstrom, Michael

2008-01-01

Several challenges await new assistant professors setting up a neuroscience lab, and obtaining sufficient research help is typically a top priority. A secondary, but no less daunting, challenge is juggling accuracy and reliability with costs and limited start-up funds. These concerns are particularly crucial for those engaging technically sophisticated measurements, such as microdialysis. We have developed straightforward procedures that our undergraduate students have utilized to successfully construct high-quality, low-cost microdialysis probes. Students mastering the various steps involved have also gained valuable insight into their use, troubleshooting, and the implications of data obtained from these constructed probes. These procedures are explained here to foster increased use in neuroscience labs that involve undergraduates, along with pointers about teaching the technique to newcomers. Students who master the techniques can pass them on to new students easily. These procedures train students in the overall research technique of microdialysis more thoroughly than when manufactured probes are used, they save money, and will eventually save the principal investigator time when students develop independence with troubleshooting and repairs. PMID:23493044

Studies on the role of dopamine in the degeneration of 5-HT nerve endings in the brain of Dark Agouti rats following 3,4-methylenedioxymethamphetamine (MDMA or ‘ecstasy') administration

PubMed Central

Colado, M I; O'Shea, E; Granados, R; Esteban, B; Martín, A B; Green, A R

1999-01-01

We investigated whether dopamine plays a role in the neurodegeneration of 5-hydroxytryptamine (5-HT) nerve endings occurring in Dark Agouti rat brain after 3,4-methylenedioxymethamphetamine (MDMA or ‘ecstasy') administration. Haloperidol (2 mg kg−1 i.p.) injected 5 min prior and 55 min post MDMA (15 mg kg−1 i.p.) abolished the acute MDMA-induced hyperthermia and attenuated the neurotoxic loss of 5-HT 7 days later. When the rectal temperature of MDMA+haloperidol treated rats was kept elevated, this protective effect was marginal. MDMA (15 mg kg−1) increased the dopamine concentration in the dialysate from a striatal microdialysis probe by 800%. L-DOPA (25 mg kg−1 i.p., plus benserazide, 6.25 mg kg−1 i.p.) injected 2 h after MDMA (15 mg kg−1) enhanced the increase in dopamine in the dialysate, but subsequent neurodegeneration was unaltered. L-DOPA (25 mg kg−1) injected before a sub-toxic dose of MDMA (5 mg kg−1) failed to induce neurodegeneration. The MDMA-induced increase in free radical formation in the hippocampus (indicated by increased 2,3- and 2,5-dihydroxybenzoic acid in a microdialysis probe perfused with salicylic acid) was unaltered by L-DOPA. The neuroprotective drug clomethiazole (50 mg kg−1 i.p.) did not influence the MDMA-induced increase in extracellular dopamine. These data suggest that previous observations on the protective effect of haloperidol and potentiating effect of L-DOPA on MDMA-induced neurodegeneration may have resulted from effects on MDMA-induced hyperthermia. The increased extracellular dopamine concentration following MDMA may result from effects of MDMA on dopamine re-uptake, monoamine oxidase and 5-HT release rather than an ‘amphetamine-like' action on dopamine release, thus explaining why the drug does not induce degeneration of dopamine nerve endings. PMID:10193771

Strategies for enhancing catecholamine-mediated neurotransmission

NASA Technical Reports Server (NTRS)

Wurtman, Richard J.

1992-01-01

Major findings made during this project period included the following observations: changes in tyrosine availability do affect brain dopamine release, as assessed by in vivo microdialysis, but that neuronal feedback mechanisms limit the durations of this effect except when dopaminergic neurotransmission has been deficient; the circulating hormone TRH markedly stimulates brain dopamine release, an effect probably mediated by its diketopiperazine metabolite; the amount of circulating L-dopa which enters the brain is both enhanced by carbohydrate consumption and suppressed by protein intake (both nutritional effects can be damaging, inasmuch as a sudden rush of L-dopa into the brain can facilitate dyskinesias, while the inhibition of brain L-dopa uptake by proteins suppresses its conversion to brain dopamine; an appropriate mixture of dietary proteins and carbohydrates can obviate both effects); serotonin release from superfused hypothalamic slices is a linear function of available tryptophan levels throughout the normal dynamic range; the daily rhythm in plasma melatonin levels is abnormal both in the sudden infant death syndrome and in women with secondary amenorrhea; tyrosine can potentiate the anorectic effects of widely-used sympathomimetic drugs; newly-described COMT inhibitors can enhance brain dopamine release in vivo; and a cell culture system, based on Y-79 (retinoblast) cells, exists in which melatonin reliably suppresses dopamine release.

Multimodal brain monitoring in fulminant hepatic failure

PubMed Central

Paschoal Jr, Fernando Mendes; Nogueira, Ricardo Carvalho; Ronconi, Karla De Almeida Lins; de Lima Oliveira, Marcelo; Teixeira, Manoel Jacobsen; Bor-Seng-Shu, Edson

2016-01-01

Acute liver failure, also known as fulminant hepatic failure (FHF), embraces a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction, and hepatic encephalopathy. Cerebral edema and intracranial hypertension are common causes of mortality in patients with FHF. The management of patients who present acute liver failure starts with determining the cause and an initial evaluation of prognosis. Regardless of whether or not patients are listed for liver transplantation, they should still be monitored for recovery, death, or transplantation. In the past, neuromonitoring was restricted to serial clinical neurologic examination and, in some cases, intracranial pressure monitoring. Over the years, this monitoring has proven insufficient, as brain abnormalities were detected at late and irreversible stages. The need for real-time monitoring of brain functions to favor prompt treatment and avert irreversible brain injuries led to the concepts of multimodal monitoring and neurophysiological decision support. New monitoring techniques, such as brain tissue oxygen tension, continuous electroencephalogram, transcranial Doppler, and cerebral microdialysis, have been developed. These techniques enable early diagnosis of brain hemodynamic, electrical, and biochemical changes, allow brain anatomical and physiological monitoring-guided therapy, and have improved patient survival rates. The purpose of this review is to discuss the multimodality methods available for monitoring patients with FHF in the neurocritical care setting. PMID:27574545

Fornix deep brain stimulation enhances acetylcholine levels in the hippocampus.

PubMed

Hescham, Sarah; Jahanshahi, Ali; Schweimer, Judith V; Mitchell, Stephen N; Carter, Guy; Blokland, Arjan; Sharp, Trevor; Temel, Yasin

2016-11-01

Deep brain stimulation (DBS) of the fornix has gained interest as a potential therapy for advanced treatment-resistant dementia, yet the mechanism of action remains widely unknown. Previously, we have reported beneficial memory effects of fornix DBS in a scopolamine-induced rat model of dementia, which is dependent on various brain structures including hippocampus. To elucidate mechanisms of action of fornix DBS with regard to memory restoration, we performed c-Fos immunohistochemistry in the hippocampus. We found that fornix DBS induced a selective activation of cells in the CA1 and CA3 subfields of the dorsal hippocampus. In addition, hippocampal neurotransmitter levels were measured using microdialysis before, during and after 60 min of fornix DBS in a next experiment. We observed a substantial increase in the levels of extracellular hippocampal acetylcholine, which peaked 20 min after stimulus onset. Interestingly, hippocampal glutamate levels did not change compared to baseline. Therefore, our findings provide first experimental evidence that fornix DBS activates the hippocampus and induces the release of acetylcholine in this region.

R-modafinil attenuates nicotine-taking and nicotine-seeking behavior in alcohol-preferring rats.

PubMed

Wang, Xiao-Fei; Bi, Guo-Hua; He, Yi; Yang, Hong-Ju; Gao, Jun-Tao; Okunola-Bakare, Oluyomi M; Slack, Rachel D; Gardner, Eliot L; Xi, Zheng-Xiong; Newman, Amy Hauck

2015-06-01

(±)-Modafinil (MOD) is used clinically for the treatment of sleep disorders and has been investigated as a potential medication for the treatment of psychostimulant addiction. However, the therapeutic efficacy of (±)-MOD for addiction is inconclusive. Herein we used animal models of self-administration and in vivo microdialysis to study the pharmacological actions of R-modafinil (R-MOD) and S-modafinil (S-MOD) on nicotine-taking and nicotine-seeking behavior, and mechanisms underlying such actions. We found that R-MOD is more potent and effective than S-MOD in attenuating nicotine self-administration in Long-Evans rats. As Long-Evans rats did not show a robust reinstatement response to nicotine, we used alcohol-preferring rats (P-rats) that display much higher reinstatement responses to nicotine than Long-Evans rats. We found that R-MOD significantly inhibited intravenous nicotine self-administration, nicotine-induced reinstatement, and nicotine-associated cue-induced drug-seeking behavior in P-rats. R-MOD alone neither sustained self-administration in P-rats previously self-administering nicotine nor reinstated extinguished nicotine-seeking behavior. The in vivo brain microdialysis assays demonstrated that R-MOD alone produced a slow-onset moderate increase in extracellular DA. Pretreatment with R-MOD dose-dependently blocked nicotine-induced dopamine (DA) release in the nucleus accumbens (NAc) in both naive and nicotine self-administrating rats, suggesting a DA-dependent mechanism underlying mitigation of nicotine's effects. In conclusion, the present findings support further investigation of R-MOD for treatment of nicotine dependence in humans.

R-Modafinil Attenuates Nicotine-Taking and Nicotine-Seeking Behavior in Alcohol-Preferring Rats

PubMed Central

Wang, Xiao-Fei; Bi, Guo-Hua; He, Yi; Yang, Hong-Ju; Gao, Jun-Tao; Okunola-Bakare, Oluyomi M; Slack, Rachel D; Gardner, Eliot L; Xi, Zheng-Xiong; Newman, Amy Hauck

2015-01-01

(±)-Modafinil (MOD) is used clinically for the treatment of sleep disorders and has been investigated as a potential medication for the treatment of psychostimulant addiction. However, the therapeutic efficacy of (±)-MOD for addiction is inconclusive. Herein we used animal models of self-administration and in vivo microdialysis to study the pharmacological actions of R-modafinil (R-MOD) and S-modafinil (S-MOD) on nicotine-taking and nicotine-seeking behavior, and mechanisms underlying such actions. We found that R-MOD is more potent and effective than S-MOD in attenuating nicotine self-administration in Long–Evans rats. As Long–Evans rats did not show a robust reinstatement response to nicotine, we used alcohol-preferring rats (P-rats) that display much higher reinstatement responses to nicotine than Long–Evans rats. We found that R-MOD significantly inhibited intravenous nicotine self-administration, nicotine-induced reinstatement, and nicotine-associated cue-induced drug-seeking behavior in P-rats. R-MOD alone neither sustained self-administration in P-rats previously self-administering nicotine nor reinstated extinguished nicotine-seeking behavior. The in vivo brain microdialysis assays demonstrated that R-MOD alone produced a slow-onset moderate increase in extracellular DA. Pretreatment with R-MOD dose-dependently blocked nicotine-induced dopamine (DA) release in the nucleus accumbens (NAc) in both naive and nicotine self-administrating rats, suggesting a DA-dependent mechanism underlying mitigation of nicotine's effects. In conclusion, the present findings support further investigation of R-MOD for treatment of nicotine dependence in humans. PMID:25613829

[In vitro and in vivo recoveries of cutaneous micro-dialysis probe of paeonol, eugenol and piperine].

PubMed

Yang, Chang; Bai, Jie; Du, Shou-Ying; Cui, Ya-Hua; Zhang, Qin-Shuai; Ma, Jun-Ming

2016-11-01

To establish a method for detecting micro-dialysis recovery of paeonol, eugenol and piperine in Huoxue Zhitong patch, in order to provide the basis for further percutaneous pharmacokinetics studies. The concentrations of paeonol, eugenol and piperine in dialysates were determined by HPLC, and probe deliveries were calculated respectively. The effects of concentration and calibration approaches on the micro-dialysis probe deliveries of the three components were investigated, and their probe absorbability, in vitro and in vivo probe stability and repeatability were also studied.The results indicated that little paeonol, eugenol and piperine were observed in probes with 30% alcohol as the perfusate, and could be cleaned from probe in a short time. And the in vivo and in vitro probe deliveries of three components were stable within 8 h, drug-containing solution and blank perfusate were alternatively used for three times, and the in vivo and in vitro probe deliveries of three components were basically unchanged. The in vitro recoveries of paeonol, eugenol and piperine with a range of concentration were respectively (45.7±4.66)%, (27.82±2.95)%, (41.3±3.96)%, which indicated no concentration independent. Under the same conditions, the similar delivery was observed by dialysis, retrodialysis and no-net flux. Therefore, the concentrations of analyses of the collected fraction could be calibrated by in vitro or in vivo recoveries. Meanwhile, this also proved that the micro-dialysis method built by this study is applicable to the study on percutaneous pharmacokinetics of Huoxue Zhitong patch. Copyright© by the Chinese Pharmaceutical Association.

Screening and analysis of bioactive compounds with biofingerprinting chromatogram analysis of traditional Chinese medicines targeting DNA by microdialysis/HPLC.

PubMed

Su, Xingye; Kong, Liang; Li, Xin; Chen, Xueguo; Guo, Ming; Zou, Hanfa

2005-05-27

Biofingerprinting chromatogram analysis, which is defined as the comparison of fingerprinting chromatograms of the extract of traditional Chinese medicines (TCMs) before and after the interaction with biological systems (DNA, protein, cell, etc.), was proposed for screening and analysis of the multiple bioactive compounds in TCMs. A method of microdialysis sampling combined with high performance liquid chromatography (HPLC) was applied to the study of DNA-binding property for the extracts of TCMs. Seven compounds were found to bind to calf thymus DNA (ct-DNA) from the TCMs of Coptis chinensis Franch (Coptis), but only three ones from Phellodendron amurense Rupr. (Phellodendron) and none from Sophoraflavescens Ait. (Sophora) to bind to ct-DNA, respectively. Three of them were identified as berberine, palmatine and jatrorrhizine and their association constants (K) to ct-DNA were determined by microdialysis/HPLC. Competitive binding behaviors of them to ct-DNA were also investigated.

Alterations in brain extracellular dopamine and glycine levels following combined administration of the glycine transporter type-1 inhibitor Org-24461 and risperidone.

PubMed

Nagy, Katalin; Marko, Bernadett; Zsilla, Gabriella; Matyus, Peter; Pallagi, Katalin; Szabo, Geza; Juranyi, Zsolt; Barkoczy, Jozsef; Levay, Gyorgy; Harsing, Laszlo G

2010-12-01

The most dominant hypotheses for the pathogenesis of schizophrenia have focused primarily upon hyperfunctional dopaminergic and hypofunctional glutamatergic neurotransmission in the central nervous system. The therapeutic efficacy of all atypical antipsychotics is explained in part by antagonism of the dopaminergic neurotransmission, mainly by blockade of D(2) dopamine receptors. N-methyl-D-aspartate (NMDA) receptor hypofunction in schizophrenia can be reversed by glycine transporter type-1 (GlyT-1) inhibitors, which regulate glycine concentrations at the vicinity of NMDA receptors. Combined drug administration with D(2) dopamine receptor blockade and activation of hypofunctional NMDA receptors may be needed for a more effective treatment of positive and negative symptoms and the accompanied cognitive deficit in schizophrenia. To investigate this type of combined drug administration, rats were treated with the atypical antipsychotic risperidone together with the GlyT-1 inhibitor Org-24461. Brain microdialysis was applied in the striatum of conscious rats and determinations of extracellular dopamine, DOPAC, HVA, glycine, glutamate, and serine concentrations were carried out using HPLC/electrochemistry. Risperidone increased extracellular concentrations of dopamine but failed to influence those of glycine or glutamate measured in microdialysis samples. Org-24461 injection reduced extracellular dopamine concentrations and elevated extracellular glycine levels but the concentrations of serine and glutamate were not changed. When risperidone and Org-24461 were added in combination, a decrease in extracellular dopamine concentrations was accompanied with sustained elevation of extracellular glycine levels. Interestingly, the extracellular concentrations of glutamate were also enhanced. Our data indicate that coadministration of an antipsychotic with a GlyT-1 inhibitor may normalize hypofunctional NMDA receptor-mediated glutamatergic neurotransmission with reduced dopaminergic side effects characteristic for antipsychotic medication.

Cochlear microdialysis for quantification of dexamethasone and fluorescein entry into scala tympani during round window administration.

PubMed

Hahn, Hartmut; Kammerer, Bernd; DiMauro, Andre; Salt, Alec N; Plontke, Stefan K

2006-02-01

Before new drugs for the treatment of inner ear disorders can be studied in controlled clinical trials, it is important that their pharmacokinetics be established in inner ear fluids. Microdialysis allows drug levels to be measured in perilymph without the volume disturbances and potential cerebrospinal fluid contamination associated with fluid sampling. The aims of this study were to show: (i) that despite low recovery rates from miniature dialysis probes, significant amounts of drug are removed from small fluid compartments, (ii) that dialysis sampling artifacts can be accounted for using computer simulations and (iii) that microdialysis allows quantification of the entry rates through the round window membrane (RWM) into scala tympani (ST). Initial experiments used microdialysis probes in small compartments in vitro containing sodium fluorescein. Stable concentrations were observed in large compartments (1000 microl) but significant concentration declines were observed in smaller compartments (100, 10 and 5.6 microl) comparable to the size of the inner ear. Computer simulations of these experiments closely approximated the experimental data. In in vivo experiments, sodium fluorescein 10 mg/ml and dexamethasone-dihydrogen-phosphate disodium salt 8 mg/ml were simultaneously applied to the RWM of guinea pigs. Perilymph concentration in the basal turn of ST was monitored using microdialysis. The fluorescein concentration reached after 200 min application (585+/-527 microg/ml) was approximately twice that of dexamethasone phosphate (291+/-369 microg/ml). Substantial variation in concentrations was found between animals by approximately a factor of 34 for fluorescein and at least 41 for dexamethasone phosphate. This is, to a large extent, thought to be the result of the RWM permeability varying in different animals. It was not caused by substance analysis variations, because two different analytic methods were used and the concentration ratio between the two substances remained nearly constant across the experiments and because differences were apparent for the repeated samples obtained in each animal. Interpretation of the results using computer simulations allowed RWM permeability to be quantified. It also demonstrated, however, that cochlear clearance values could not be reliably obtained with microdialysis because of the significant contribution of dialysis to clearance. The observed interanimal variation, e.g., in RWM permeability, is likely to be clinically relevant to the local application of drugs in patients.

Cochlear Microdialysis for Quantification of Dexamethasone and Fluorescein Entry into Scala Tympani During Round Window Administration

PubMed Central

Hahn, Hartmut; Kammerer, Bernd; DiMauro, Andre; Salt, Alec N.; Plontke, Stefan K.

2006-01-01

Before new drugs for the treatment of inner ear disorders can be studied in controlled clinical trials, it is important that their pharmacokinetics be established in inner ear fluids. Microdialysis allows drug levels to be measured in perilymph without the volume disturbances and potential cerebrospinal fluid contamination associated with fluid sampling. The aims of this study were to show: (i) that despite low recovery rates from miniature dialysis probes, significant amounts of drug are removed from small fluid compartments, (ii) that dialysis sampling artifacts can be accounted for using computer simulations and (iii) that microdialysis allows quantification of the entry rates through the round window membrane (RWM) into scala tympani (ST). Initial experiments used microdialysis probes in small compartments in vitro containing sodium fluorescein. Stable concentrations were observed in large compartments (1000 μl) but significant concentration declines were observed in smaller compartments (100, 10 and 5.6 μl) comparable to the size of the inner ear. Computer simulations of these experiments closely approximated the experimental data. In in vivo experiments, sodium fluorescein 10 mg/ml and dexamethasone-dihydrogen-phosphate disodium salt 8 mg/ml were simultaneously applied to the RWM of guinea pigs. Perilymph concentration in the basal turn of ST was monitored using microdialysis. The fluorescein concentration reached after 200 min application (585 ± 527 μg/ml) was approximately twice that of dexamethasone phosphate (291 ± 369 μg/ml). Substantial variation in concentrations was found between animals by approximately a factor of 34 for fluorescein and at least 41 for dexamethasone phosphate. This is, to a large extent, thought to be the result of the RWM permeability varying in different animals. It was not caused by substance analysis variations, because two different analytic methods were used and the concentration ratio between the two substances remained nearly constant across the experiments and because differences were apparent for the repeated samples obtained in each animal. Interpretation of the results using computer simulations allowed RWM permeability to be quantified. It also demonstrated, however, that cochlear clearance values could not be reliably obtained with microdialysis because of the significant contribution of dialysis to clearance. The observed interanimal variation, e.g., in RWM permeability, is likely to be clinically relevant to the local application of drugs in patients. PMID:16442251

Medullary serotonergic neurones modulate the ventilatory response to hypercapnia, but not hypoxia in conscious rats.

PubMed

Taylor, Natalie C; Li, Aihua; Nattie, Eugene E

2005-07-15

Serotonergic neurones in the mammalian medullary raphe region (MRR) have been implicated in central chemoreception and the modulation of the ventilatory response to hypercapnia, and may also be involved in the ventilatory response to hypoxia. In this study, we ask whether ventilatory responses across arousal states are affected when the 5-hydroxytryptamine 1A receptor (5-HT1A) agonist (R)-(+)-8-hydroxy-2(di-n-propylamino)tetralin (DPAT) is microdialysed into the MRR of the unanaesthetized adult rat. Microdialysis of 1, 10 and 30 mM DPAT into the MRR significantly decreased absolute ventilation values(VE) during 7% CO2 breathing by 21%, 19% and 30%, respectively, in wakefulness compared to artificial cerebrospinal fluid (aCSF) microdialysis, due to decreases in tidal volume (VT) and not in frequency (f), similar to what occurred during non-rapid eye movement (NREM) sleep. The concentration-dependence of the hypercapnic ventilatory effect might be due to differences in tissue distribution of DPAT. DPAT (30 mM) changed room air breathing pattern by increasing f and decreasing VT. As evidenced by a sham control group, repeated experimentation and microdialysis of aCSF alone had no effect on the ventilatory response to 7% CO2 during wakefulness or sleep. Unlike during hypercapnia, microdialysis of 30 mM DPAT into the MRR did not change the ventilatory response to 10% O2. Additionally, 10 and 30 mM DPAT MRR microdialysis decreased body temperature, and 30 mM DPAT increased the percentage of experimental time in wakefulness. We conclude that serotonergic activity in the MRR plays a role in the ventilatory response to hypercapnia, but not to hypoxia, and that MRR 5-HT1A receptors are also involved in thermoregulation and arousal.

A High-Performance Application Specific Integrated Circuit for Electrical and Neurochemical Traumatic Brain Injury Monitoring.

PubMed

Pagkalos, Ilias; Rogers, Michelle L; Boutelle, Martyn G; Drakakis, Emmanuel M

2018-05-22

This paper presents the first application specific integrated chip (ASIC) for the monitoring of patients who have suffered a Traumatic Brain Injury (TBI). By monitoring the neurophysiological (ECoG) and neurochemical (glucose, lactate and potassium) signals of the injured human brain tissue, it is possible to detect spreading depolarisations, which have been shown to be associated with poor TBI patient outcome. This paper describes the testing of a new 7.5 mm 2 ASIC fabricated in the commercially available AMS 0.35 μm CMOS technology. The ASIC has been designed to meet the demands of processing the injured brain tissue's ECoG signals, recorded by means of depth or brain surface electrodes, and neurochemical signals, recorded using microdialysis coupled to microfluidics-based electrochemical biosensors. The potentiostats use switchedcapacitor charge integration to record currents with 100 fA resolution, and allow automatic gain changing to track the falling sensitivity of a biosensor. This work supports the idea of a "behind the ear" wireless microplatform modality, which could enable the monitoring of currently non-monitored mobile TBI patients for the onset of secondary brain injury. ©2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Hyperbaric oxygen therapy ameliorates acute brain injury after porcine intracerebral hemorrhage at high altitude.

PubMed

Zhu, Hai-tao; Bian, Chen; Yuan, Ji-chao; Liao, Xiao-jun; Liu, Wei; Zhu, Gang; Feng, Hua; Lin, Jiang-kai

2015-06-15

Intracerebral hemorrhage (ICH) at high altitude is not well understood to date. This study investigates the effects of high altitude on ICH, and examines the acute neuroprotection of hyperbaric oxygen (HBO) therapy against high-altitude ICH. Minipigs were placed in a hypobaric chamber for 72 h before the operation. ICH was induced by an infusion of autologous arterial blood (3 ml) into the right basal ganglia. Animals in the high-altitude ICH group received HBO therapy (2.5 ATA for 60 min) 30 min after ICH. Blood gas, blood glucose and brain tissue oxygen partial pressure (PbtO2) were monitored continuously for animals from all groups, as were microdialysis products including glucose, lactate, pyruvate and glutamate in perihematomal tissue from 3 to 12 h post-ICH. High-altitude ICH animals showed significantly lower PbtO2, higher lactate/pyruvate ratio (LPR) and glutamate levels than low-altitude ICH animals. More severe neurological deficits, brain edema and neuronal damage were also observed in high-altitude ICH. After HBO therapy, PbtO2 was significantly increased and LPR and glutamate levels were significantly decreased. Brain edema, neurological deficits and neuronal damage were also ameliorated. The data suggested a more serious disturbance of tissue oxygenation and cerebral metabolism in the acute stage after ICH at high altitude. Early HBO treatment reduced acute brain injury, perhaps through a mechanism involving the amelioration of the derangement of cerebral oxygenation and metabolism following high-altitude ICH.

Leucine acts in the brain to suppress food intake but does not function as a physiological signal of low dietary protein

PubMed Central

Laeger, Thomas; Reed, Scott D.; Henagan, Tara M.; Fernandez, Denise H.; Taghavi, Marzieh; Addington, Adele; Münzberg, Heike; Martin, Roy J.; Hutson, Susan M.

2014-01-01

Intracerebroventricular injections of leucine are sufficient to suppress food intake, but it remains unclear whether brain leucine signaling represents a physiological signal of protein balance. We tested whether variations in dietary and circulating levels of leucine, or all three branched-chain amino acids (BCAAs), contribute to the detection of reduced dietary protein. Of the essential amino acids (EAAs) tested, only intracerebroventricular injection of leucine (10 μg) was sufficient to suppress food intake. Isocaloric low- (9% protein energy; LP) or normal- (18% protein energy) protein diets induced a divergence in food intake, with an increased consumption of LP beginning on day 2 and persisting throughout the study (P < 0.05). Circulating BCAA levels were reduced the day after LP diet exposure, but levels subsequently increased and normalized by day 4, despite persistent hyperphagia. Brain BCAA levels as measured by microdialysis on day 2 of diet exposure were reduced in LP rats, but this effect was most prominent postprandially. Despite these diet-induced changes in BCAA levels, reducing dietary leucine or total BCAAs independently from total protein was neither necessary nor sufficient to induce hyperphagia, while chronic infusion of EAAs into the brain of LP rats failed to consistently block LP-induced hyperphagia. Collectively, these data suggest that circulating BCAAs are transiently reduced by dietary protein restriction, but variations in dietary or brain BCAAs alone do not explain the hyperphagia induced by a low-protein diet. PMID:24898843

A novel method for the determination of ascorbic acid and antioxidant capacity in Opuntia ficus indica using in vivo microdialysis.

PubMed

Pretti, L; Bazzu, G; Serra, P A; Nieddu, G

2014-03-15

A simple and rapid method was developed for in vivo simultaneous determination of ascorbic-acid and antioxidant capacity in microdialysates from cladodes of Opuntia ficus-indica (L.) Miller. The method is verified in water-stressed plants, as compared with a well-watered test controls. The microdialysis probe construction and insertion procedure was specifically developed to minimise the tissue trauma of the plant and to obtain optimal dialysis performance. Microdialysis was performed using a flow rate of 3 μL/min and the samples were analysed by HPLC coupled to electrochemical detection of ascorbic-acid and DPPH-determined antioxidant capacity. Our data indicate exponential decay of the concentrations of the analysed compounds as a function of microdialysis sampling time. Water-stressed Opuntia show decreased ascorbic acid levels and increased the others antioxidants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Critical evaluation of colon submucosal microdialysis in awake, mobile rats.

PubMed

Cibicek, Norbert; Ehrmann, Jiri; Proskova, Jitka; Vecera, Rostislav

2018-01-01

Sensors able to record large bowel physiology and biochemistry in situ in awake rodents are lacking. Microdialysis is a mini-invasive technique that may be utilized to continuously deliver or recover low-molecular substances from various tissues. In this experiment we evaluated the feasibility of in vivo microdialysis to monitor extracellular fluid chemistry in the descending colon submucosa of conscious, freely moving rodents. Following surgical implantation of a microdialysis probe, male Wistar rats were housed in metabolic cages where they were analgized and clinically followed for four days with free access to standard diet and water. To assess local microcirculation and probe function, glucose, lactate, glucose-to-lactate ratio and urea clearance were determined in the dialysates from the three postoperative days with focus on the final 24-h period. In an attempt to mitigate the expected tissue inflammatory response, one group of animals had the catheters perfused with 5-aminosalicylic acid-enriched medium with final concentration 1 μmol/L. For verification of probe position and the assessment of the surrounding foreign body reaction, standard histological and immunohistochemical methods were employed. Microdialysis of rat gut is associated with considerable technical challenges that may lead to the loss of probe function and high drop-out rate. In this setting, limited data did not allow to draw any firm conclusion regarding local anti-inflammatory effectiveness of 5-aminosalicylic acid perfusion. Although intestinal microdialysis may be suitable for larger anesthetized animals, low reproducibility of the presented method compromises its routine experimental use in awake and freely moving small-sized rodents.

Neuronal LRP1 Regulates Glucose Metabolism and Insulin Signaling in the Brain

PubMed Central

Liu, Chia-Chen; Hu, Jin; Tsai, Chih-Wei; Yue, Mei; Melrose, Heather L.; Kanekiyo, Takahisa

2015-01-01

Alzheimer's disease (AD) is a neurological disorder characterized by profound memory loss and progressive dementia. Accumulating evidence suggests that Type 2 diabetes mellitus, a metabolic disorder characterized by insulin resistance and glucose intolerance, significantly increases the risk for developing AD. Whereas amyloid-β (Aβ) deposition and neurofibrillary tangles are major histological hallmarks of AD, impairment of cerebral glucose metabolism precedes these pathological changes during the early stage of AD and likely triggers or exacerbates AD pathology. However, the mechanisms linking disturbed insulin signaling/glucose metabolism and AD pathogenesis remain unclear. The low-density lipoprotein receptor-related protein 1 (LRP1), a major apolipoprotein E receptor, plays critical roles in lipoprotein metabolism, synaptic maintenance, and clearance of Aβ in the brain. Here, we demonstrate that LRP1 interacts with the insulin receptor β in the brain and regulates insulin signaling and glucose uptake. LRP1 deficiency in neurons leads to impaired insulin signaling as well as reduced levels of glucose transporters GLUT3 and GLUT4. Consequently, glucose uptake is reduced. By using an in vivo microdialysis technique sampling brain glucose concentration in freely moving mice, we further show that LRP1 deficiency in conditional knock-out mice resulted in glucose intolerance in the brain. We also found that hyperglycemia suppresses LRP1 expression, which further exacerbates insulin resistance, glucose intolerance, and AD pathology. As loss of LRP1 expression is seen in AD brains, our study provides novel insights into insulin resistance in AD. Our work also establishes new targets that can be explored for AD prevention or therapy. PMID:25855193

The atypical antipsychotic quetiapine increases both noradrenaline and dopamine release in the rat prefrontal cortex.

PubMed

Pira, Luigi; Mongeau, Raymond; Pani, Luca

2004-11-03

Quetiapine is a novel atypical antipsychotic drug with multi-receptorial affinity. Using in vivo microdialysis, we investigated if quetiapine modulates extracellular noradrenaline and dopamine in brain areas generally believed to be involved in the pathophysiology of schizophrenia and in the action of antipsychotic drugs. Quetiapine (5, 10 and 20 mg/kg, i.p.) increased levels of noradrenaline in both the prefrontal cortex and the caudate nucleus, while it increased dopamine levels mainly in the prefrontal cortex. It is argued that the marked increase of dopaminergic transmission in the prefrontal cortex induced by quetiapine might be relevant to its therapeutical action.

Rasgrf2 controls dopaminergic adaptations to alcohol in mice.

PubMed

Easton, Alanna C; Rotter, Andrea; Lourdusamy, Anbarasu; Desrivières, Sylvane; Fernández-Medarde, Alberto; Biermann, Teresa; Fernandes, Cathy; Santos, Eugenio; Kornhuber, Johannes; Schumann, Gunter; Müller, Christian P

2014-10-01

Alcohol abuse leads to serious health problems with no effective treatment available. Recent evidence suggests a role for ras-specific guanine-nucleotide releasing factor 2 (RASGRF2) in alcoholism. Rasgrf2 is a calcium sensor and MAPK/ERK activating protein, which has been linked to neurotransmitter release and monoaminergic receptor adaptations. Rasgrf2 knock out (KO) mice do not develop a dopamine response in the nucleus accumbens after an alcohol challenge and show a reduced consumption of alcohol. The present study aims to further characterise the role of Rasgrf2 in dopaminergic activation beyond the nucleus accumbens following alcohol treatment. Using in vivo microdialysis we found that alcohol induces alterations in dopamine levels in the dorsal striatum between wildtype (WT) and Rasgrf2 KO mice. There was no difference in the expression of dopamine transporter (DAT), dopamine receptor regulating factor (DRRF), or dopamine D2 receptor (DRD2) mRNA in the brain between Rasgrf2 KO and WT mice. After sub-chronic alcohol treatment, DAT and DRRF, but not DRD2 mRNA expression differed between WT and Rasgrf2 KO mice. Brain adaptations were positively correlated with splenic expression levels. These data suggest that Rasgrf2 controls dopaminergic signalling and adaptations to alcohol also in other brain regions, beyond the nucleus accumbens. Copyright © 2014 Elsevier Inc. All rights reserved.

Ethanol induces taurine release in the amygdala: an in vivo microdialysis study.

PubMed

Quertemont, E; Dahchour, A; Ward, R J; Witte, P

1999-01-01

The effect of acute IP ethanol injections on the extracellular aspartate, glutamate, taurine and GABA content of the basolateral amygdala microdialysate was investigated in relationship with total brain ethanol. Each acute intraperitoneal injection of ethanol, 0.5, 1.0, 2.0 and 3.0 g/kg body weight, induced an immediate increase in microdialysate taurine; both 0.5 and 1.0 g/kg ethanol evoked an increase during the first 20 minutes following injection which returned to baseline value by 40 minutes, despite the fact that ethanol was detectable in the brain until 60 or 120 minutes, respectively. After either 2.0 or 3.0 g/kg ethanol there was an increase in taurine of gradual intensity which gradually declined to reach baseline values by 100 minutes. In contrast, the ethanol concentration for 2.0 g/kg remained elevated at the end of the 120 minutes; approximately 25 mg ethanol/mg protein. The stimulated release of taurine within the amygdala could participate in the regulation of ethanoli-nduced changes in osmolarity, since taurine is postulated to act as an osmoregulator in the brain. Taurine could also mediate or interact with ethanol-induced central nervous system effects, as it exerts a modulatory action on cell excitability and neurotransmitter processes.

Application of long-term microdialysis in circadian rhythm research

PubMed Central

Borjigin, Jimo; Liu, Tiecheng

2008-01-01

Our laboratory has pioneered long-term microdialysis to monitor pineal melatonin secretion in living animals across multiple circadian cycles. There are numerous advantages of this approach for rhythm analysis: (1) we can precisely define melatonin onset and offset phases; (2) melatonin is a reliable and stable neuroendocrine output of the circadian clock (versus behavioral output which is sensitive to stress or other factors); (3) melatonin measurements can be performed extremely frequently, permitting high temporal resolution (10 min sampling intervals), which allows detection of slight changes in phase; (4) the measurements can be performed for more than four weeks, allowing perturbations of the circadian clock to be followed long-term in the same animals; (5) this is an automated process (microdialysis coupled with on-line HPLC analysis), which increases accuracy and bypasses the labor-intensive and error-prone manual handling of dialysis samples; and (6) our approach allows real-time investigation of circadian rhythm function and permits appropriate timely adjustments of experimental conditions. The longevity of microdialysis probes, the key to the success of this approach, depends at least in part on the methods of the construction and implantation of dialysis probes. In this article, we have detailed the procedures of construction and surgical implantation of microdialysis probes used currently in our laboratory, which are significantly improved from our previous methods. PMID:18045670

Resuscitation from experimental traumatic brain injury by magnolol therapy.

PubMed

Wang, Che-Chuan; Lin, Kao-Chang; Lin, Bor-Shyh; Chio, Chung-Ching; Kuo, Jinn-Rung

2013-10-01

The purpose of the present study was to determine whether magnolol, a free radical scavenger, mitigates the deleterious effects of traumatic brain injury (TBI). Traumatic brain injuries were induced in anesthetized male Sprague-Dawley rats using fluid percussion, and the rats were divided into groups treated with magnolol (2 mg/kg, intravenously) or vehicle. A group of rats that did not undergo TBI induction was also studied as controls. Biomarkers of TBI, including glycerol and 2,3-dihydroxybenzoic acid, were evaluated by microdialysis. Infraction volume, extent of neuronal apoptosis, and antiapoptosis factor transforming growth factor β1 (TGF-β1) were also measured. Functional outcomes were assessed by motor assays. Compared with the rats without TBI, the animals with TBI exhibited higher hippocampal glycerol and 2,3-dihydroxybenzoic acid. Relative to the vehicle-treated group, the magnolol-treated group showed decreased hippocampal levels of glycerol and hydroxyl radical levels. The magnolol-treated rats also exhibited decreased cerebral infarction volume and neuronal apoptosis and increased antiapoptosis-associated factor TGF-β1 expression. These effects were translated into improved motor function post TBI. Our results suggest that intravenous magnolol injection mitigates the deleterious effects of TBI in rats based on its potent free radical scavenging capability, and the mechanism of anti-neuronal apoptosis is partly due to an increase in TGF-β1 expression in the ischemic cortex. Copyright © 2013 Elsevier Inc. All rights reserved.

Role of neutrophils in radical production during ischemia and reperfusion of the rat brain: effect of neutrophil depletion on extracellular ascorbyl radical formation.

PubMed

Matsuo, Y; Kihara, T; Ikeda, M; Ninomiya, M; Onodera, H; Kogure, K

1995-11-01

A growing body of experimental data indicate that oxygen radicals may mediate the brain injury during ischemia-reperfusion. One potential source of oxygen radicals is activated neutrophils. To study the role of neutrophils in radical production during cerebral ischemia-reperfusion, we evaluated the effects of depletion of circulating neutrophils by administration of an anti-neutrophil monoclonal antibody (RP3) on radical formation in rats with 1-h middle cerebral artery (MCA) occlusion. In the present study, we employed a new electron spin resonance method coupled with brain microdialysis. The method uses the endogenous ascorbyl radical (AR) concentration as a marker of oxygen radicals and requires no spin-trapping agents. In the vehicle controls, extracellular AR decreased during MCA occlusion. After reperfusion, AR significantly increased at 30 min and 1 h, returned to near basal level until 2 h, and increased again at 24 h after reperfusion. In the rats treated with RP3, AR decreased during MCA occlusion to the same extent as in the vehicle control. However, RP3 treatment completely inhibited the increase in extracellular AR after reperfusion. RP3 treatment exerted no effect on the changes in extracellular ascorbate or tissue PO2 throughout the experimental period. In conclusion, neutrophils are a major source of oxygen radicals during reperfusion after focal cerebral ischemia.

The 5-HT(1A) receptor agonist, 8-OH-DPAT, attenuates stress-induced anorexia in conjunction with the suppression of hypothalamic serotonin release in rats.

PubMed

Shimizu, N; Hori, T; Ogino, C; Kawanishi, T; Hayashi, Y

2000-12-22

The effect of the selective 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) on stress-induced anorexia and serotonin (5-HT) release in the rat hypothalamus was studied with brain microdialysis. Subcutaneous injection of 8-OH-DPAT (1 mg/kg) significantly attenuated the immobilization-induced anorexia for 3 h, but had no effect during the following 9 h. Injection of 8-OH-DPAT itself had no effect on basal release of 5-HT, while it significantly blocked the immobilization-induced 5-HT release in the lateral hypothalamus. The results suggest that 8-OH-DPAT attenuated the stress-induced anorexia through the activation of 5-HT(1A) autoreceptors in dorsal raphe nucleus.

Ultrafiltrate and microdialysis DL probe in vitro recoveries: electrolytes and metabolites

NASA Technical Reports Server (NTRS)

Janle, E. M.; Cregor, M.

1996-01-01

UF ultrafiltration and DL microdialysis probes are well-suited for sampling interstitial concentrations of ions and metabolites in peripheral tissue. The first step in utilization of membrane sampling techniques is to determine the recovery characteristics of the probes in vitro.

Platelet activating factor induces transient blood-brain barrier opening to facilitate edaravone penetration into the brain.

PubMed

Fang, Weirong; Zhang, Rui; Sha, Lan; Lv, Peng; Shang, Erxin; Han, Dan; Wei, Jie; Geng, Xiaohan; Yang, Qichuan; Li, Yunman

2014-03-01

The blood-brain barrier (BBB) greatly limits the efficacy of many neuroprotective drugs' delivery to the brain, so improving drug penetration through the BBB has been an important focus of research. Here we report that platelet activating factor (PAF) transiently opened BBB and facilitated neuroprotectant edaravone penetration into the brain. Intravenous infusion with PAF induced a transient BBB opening in rats, reflected by increased Evans blue leakage and mild edema formation, which ceased within 6 h. Furthermore, rat regional cerebral blood flow (rCBF) declined acutely during PAF infusion, but recovered slowly. More importantly, this transient BBB opening significantly increased the penetration of edaravone into the brain, evidenced by increased edaravone concentrations in tissue interstitial fluid collected by microdialysis and analyzed by Ultra-performance liquid chromatograph combined with a hybrid quadrupole time-of-flight mass spectrometer (UPLC-MS/MS). Similarly, incubation of rat brain microvessel endothelial cells monolayer with 1 μM PAF for 1 h significantly increased monolayer permeability to (125)I-albumin, which recovered 1 h after PAF elimination. However, PAF incubation with rat brain microvessel endothelial cells for 1 h did not cause detectable cytotoxicity, and did not regulate intercellular adhesion molecule-1, matrix-metalloproteinase-9 and P-glycoprotein expression. In conclusion, PAF could induce transient and reversible BBB opening through abrupt rCBF decline, which significantly improved edaravone penetration into the brain. Platelet activating factor (PAF) transiently induces BBB dysfunction and increases BBB permeability, which may be due to vessel contraction and a temporary decline of regional cerebral blood flow (rCBF) triggered by PAF. More importantly, the PAF induced transient BBB opening facilitates neuroprotectant edaravone penetration into brain. The results of this study may provide a new approach to improve drug delivery into the brain. © 2013 International Society for Neurochemistry.

A comparative study on the skin penetration of pure tryptanthrin and tryptanthrin in Isatis tinctoria extract by dermal microdialysis coupled with isotope dilution ESI-LC-MS.

PubMed

Oberthür, Christine; Heinemann, Christian; Elsner, Peter; Benfeldt, Eva; Hamburger, Matthias

2003-05-01

The indolo[2,1- b]quinazoline alkaloid tryptanthrin has recently been identified as a pharmacologically active compound in Isatis tinctoria, with potent dual inhibitory activity on prostaglandin and leukotriene synthesis. To investigate the skin penetration of tryptanthrin from solutions of pure compound and Isatis extracts, we developed and validated a cutaneous microdialysis model using ex vivo pig foreleg. Microdialysis was performed by placing linear probes in the dermis of the skin in situ, and tryptanthrin concentrations in the dialysates were determined by isotope dilution electrospray ionization LC-MS in the selected ion mode. Measurable concentrations of tryptanthrin were detected 30 min after application. A dose-dependent increase in tryptanthrin concentrations in the dialysate was observed for the Isatis extracts, but not for pure tryptanthrin. Microscopic analysis showed that the pure compound crystallized from the solution but remained in an amorphous state in the extracts.

The unsuitability of implantable Doppler probes for the early detection of renal vascular complications – a porcine model for prevention of renal transplant loss

PubMed Central

Jespersen, Bente; Møldrup, Ulla; Keller, Anna K.

2017-01-01

Background Vascular occlusion is a rare, but serious complication after kidney transplantation often resulting in graft loss. We therefore aimed to develop an experimental porcine model for stepwise reduction of the renal venous blood flow and to compare an implantable Doppler probe and microdialysis for fast detection of vascular occlusion. Methods In 20 pigs, implantable Doppler probes were placed on the renal artery and vein and a microdialysis catheter was placed in the renal cortex. An arterial flowprobe served as gold standard. Following two-hour baseline measurements, the pigs were randomised to stepwise venous occlusion, complete venous occlusion, complete arterial occlusion or controls. Results All parameters were stable through baseline measurements. Glutamate and lactate measured by microdialysis increased significantly (p = 0.02 and p = 0.03 respectively) 30 minutes after a 2/3 (66%) reduction in renal blood flow. The implantable Doppler probe was not able to detect flow changes until there was total venous occlusion. Microdialysis detected changes in local metabolism after both arterial and venous occlusion; the implantable Doppler probe could only detect vascular occlusions on the vessel it was placed. Conclusions We developed a new model for stepwise renal venous blood flow occlusion. Furthermore, the first comparison of the implantable Doppler probe and microdialysis for detection of renal vascular occlusions was made. The implantable Doppler probe could only detect flow changes after a complete occlusion, whereas microdialysis detected changes earlier, and could detect both arterial and venous occlusion. Based on these results, the implantable Doppler probe for early detection of vascular occlusions cannot be recommended. PMID:28542429

Abuse-Related Neurochemical Effects of Para-Substituted Methcathinone Analogs in Rats: Microdialysis Studies of Nucleus Accumbens Dopamine and Serotonin

PubMed Central

Suyama, Julie A.; Sakloth, Farhana; Kolanos, Renata; Glennon, Richard A.; Lazenka, Matthew F.; Negus, S. Stevens

2016-01-01

Methcathinone (MCAT) is a monoamine releaser and parent compound to a new class of designer drugs that includes the synthetic cathinones mephedrone and flephedrone. Using MCAT and a series of para-substituted (or 4-substituted) MCAT analogs, it has been previously shown that expression of abuse-related behavioral effects in rats correlates both with the volume of the para substituent and in vitro neurochemical selectivity to promote monoamine release via the dopamine (DA) versus serotonin (5-HT) transporters in rat brain synaptosomes. The present study used in vivo microdialysis to determine the relationship between these previous measures and the in vivo neurochemical selectivity of these compounds to alter nucleus accumbens (NAc) DA and 5-HT levels. Male Sprague-Dawley rats were implanted with bilateral guide cannulae targeting the NAc. MCAT and five para-substituted analogs (4-F, 4-Cl, 4-Br, 4-CH3, and 4-OCH3) produced dose- and time-dependent increases in NAc DA and/or 5-HT levels. Selectivity was determined as the dose required to increase peak 5-HT levels by 250% divided by the dose required to increase peak DA levels by 250%. This measure of in vivo neurochemical selectivity varied across compounds and correlated with 1) in vivo expression of abuse-related behavioral effects (r = 0.89, P = 0.02); 2) in vitro selectivity to promote monoamine release via DA and 5-HT transporters (r = 0.95, P < 0.01); and 3) molecular volume of the para substituent (r = −0.85, P = 0.03). These results support a relationship between these molecular, neurochemical, and behavioral measures and support a role for molecular structure as a determinant of abuse-related neurochemical and behavioral effects of MCAT analogs. PMID:26645638

Blockade of the high-affinity noradrenaline transporter (NET) by the selective 5-HT reuptake inhibitor escitalopram: an in vivo microdialysis study in mice

PubMed Central

Nguyen, Hai T; Guiard, Bruno P; Bacq, Alexandre; David, Denis J; David, Indira; Quesseveur, Gaël; Gautron, Sophie; Sanchez, Connie; Gardier, Alain M

2013-01-01

BACKGROUND AND PURPOSE Escitalopram, the S(+)-enantiomer of citalopram is the most selective 5-HT reuptake inhibitor approved. Although all 5-HT selective reuptake inhibitors (SSRIs) increase extracellular levels of 5-HT ([5-HT]ext). some also enhance, to a lesser extent, extracellular levels of noradrenaline ([NA]ext). However, the mechanisms by which SSRIs activate noradrenergic transmission in the brain remain to be determined. EXPERIMENTAL APPROACH This study examined the effects of escitalopram, on both [5-HT]ext and [NA]ext in the frontal cortex (FCx) of freely moving wild-type (WT) and mutant mice lacking the 5-HT transporter (SERT−/−) by using intracerebral microdialysis. We explored the possibilities that escitalopram enhances [NA]ext, either by a direct mechanism involving the inhibition of the low- or high-affinity noradrenaline transporters, or by an indirect mechanism promoted by [5-HT]ext elevation. The forced swim test (FST) was used to investigate whether enhancing cortical [5-HT]ext and/or [NA]ext affected the antidepressant-like activity of escitalopram. KEY RESULTS In WT mice, a single systemic administration of escitalopram produced a significant increase in cortical [5-HT]ext and [NA]ext. As expected, escitalopram failed to increase cortical [5-HT]ext in SERT−/− mice, whereas its neurochemical effects on [NA]ext persisted in these mutants. In WT mice subjected to the FST, escitalopram increased swimming parameters without affecting climbing behaviour. Finally, escitalopram, at relevant concentrations, failed to inhibit cortical noradrenaline and 5-HT uptake mediated by low-affinity monoamine transporters. CONCLUSIONS AND IMPLICATIONS These experiments suggest that escitalopram enhances, although moderately, cortical [NA]extin vivo by a direct mechanism involving the inhibition of the high-affinity noradrenaline transporter (NET). PMID:22233336

Microdialysate concentration changes do not provide sufficient information to evaluate metabolic effects of lactate supplementation in brain-injured patients

PubMed Central

Rothman, Douglas L; Nordström, Carl-Henrik

2016-01-01

Cerebral microdialysis is a widely used clinical tool for monitoring extracellular concentrations of selected metabolites after brain injury and to guide neurocritical care. Extracellular glucose levels and lactate/pyruvate ratios have high diagnostic value because they can detect hypoglycemia and deficits in oxidative metabolism, respectively. In addition, patterns of metabolite concentrations can distinguish between ischemia and mitochondrial dysfunction, and are helpful to choose and evaluate therapy. Increased intracranial pressure can be life-threatening after brain injury, and hypertonic solutions are commonly used for pressure reduction. Recent reports have advocated use of hypertonic sodium lactate, based on claims that it is glucose sparing and provides an oxidative fuel for injured brain. However, changes in extracellular concentrations in microdialysate are not evidence that a rise in extracellular glucose level is beneficial or that lactate is metabolized and improves neuroenergetics. The increase in glucose concentration may reflect inhibition of glycolysis, glycogenolysis, and pentose phosphate shunt pathway fluxes by lactate flooding in patients with mitochondrial dysfunction. In such cases, lactate will not be metabolizable and lactate flooding may be harmful. More rigorous approaches are required to evaluate metabolic and physiological effects of administration of hypertonic sodium lactate to brain-injured patients. PMID:27604313

A Comparison of Oxidative Lactate Metabolism in Traumatically Injured Brain and Control Brain.

PubMed

Jalloh, Ibrahim; Helmy, Adel; Howe, Duncan J; Shannon, Richard J; Grice, Peter; Mason, Andrew; Gallagher, Clare N; Murphy, Michael P; Pickard, John D; Menon, David K; Carpenter, T Adrian; Hutchinson, Peter J; Carpenter, Keri L H

2018-05-18

Metabolic abnormalities occur after traumatic brain injury (TBI). Glucose is conventionally regarded as the major energy substrate, although lactate can also be an energy source. We compared 3- 13 C lactate metabolism in TBI with "normal" control brain and muscle, measuring 13 C-glutamine enrichment to assess tricarboxylic acid (TCA) cycle metabolism. Microdialysis catheters in brains of nine patients with severe TBI, five non-TBI brain surgical patients, and five resting muscle (non-TBI) patients were perfused (24 h in brain, 8 h in muscle) with 8 mmol/L sodium 3- 13 C lactate. Microdialysate analysis employed ISCUS and nuclear magnetic resonance. In TBI, with 3- 13 C lactate perfusion, microdialysate glucose concentration increased nonsignificantly (mean +11.9%, p = 0.463), with significant increases (p = 0.028) for lactate (+174%), pyruvate (+35.8%), and lactate/pyruvate ratio (+101.8%). Microdialysate 13 C-glutamine fractional enrichments (median, interquartile range) were: for C4 5.1 (0-11.1) % in TBI and 5.7 (4.6-6.8) % in control brain, for C3 0 (0-5.0) % in TBI and 0 (0-0) % in control brain, and for C2 2.9 (0-5.7) % in TBI and 1.8 (0-3.4) % in control brain. 13 C-enrichments were not statistically different between TBI and control brain, showing both metabolize 3- 13 C lactate via TCA cycle, in contrast to muscle. Several patients with TBI exhibited 13 C-glutamine enrichment above the non-TBI control range, suggesting lactate oxidative metabolism as a TBI "emergency option."

Dopamine D1 receptor-dependent regulation of extracellular citrulline level in the rat nucleus accumbens during conditioned fear response.

PubMed

Saulskaya, Natalia B; Fofonova, Nellia V; Sudorghina, Polina V; Saveliev, Sergey A

2008-08-01

Nucleus accumbens (N.Acc) contains a subclass of nitric oxide (NO)-generating interneurons that are presumably regulated by the dopamine input. Receptor mechanisms underlying dopamine-NO interaction in the N.Acc are poorly understood. In the current study, we used in vivo microdialysis combined with high-performance liquid chromatography to examine participation of dopamine D1 receptors in regulation of extracellular levels of citrulline (an NO co-product) in the medial N.Acc of Sprague-Dawley rats during both pharmacological challenge and a conditioned fear response. The intraaccumbal infusion of the D1 receptor agonist SKF-38393 (100-500 microM) increased dose-dependently the local dialysate citrulline levels. The SKF-38393-induced increase in extracellular citrulline was prevented by intraaccumbal infusions of 500 microM 7-nitroindazole, a neuronal NO synthase inhibitor. In behavioral microdialysis experiment, the accumbal levels of extracellular citrulline markedly increased in rats given a mild footshock paired with tone. The presentation of the tone previously paired with footshock (the conditioned fear response) produced a "conditioned" rise of extracellular citrulline levels in the N.Acc which was attenuated by intraaccumbal infusion of 100 microM SCH-23390, a dopamine D1 receptor antagonist, and prevented by intraaccumbal infusion of 500 microM 7-nitroindazole. The results suggest that in the N.Acc, the dopamine D1 receptors might regulate the neuronal NO synthase activity; this dopamine-dependent mechanism seems to participate in activation of the neuronal NO synthase and probably NO formation in this brain area during the conditioned fear response.

An in vitro Comparison of Microdialysis Relative Recovery of Met- and Leu-Enkephalin Using Cyclodextrins and Antibodies as Affinity Agents

PubMed Central

Fletcher, Heidi J.; Stenken, Julie A.

2008-01-01

Cyclodextrins and antibodies have been used as affinity agents to improve relative recovery during microdialysis sampling. Two neuropeptides, methionine-enkephalin (ME) and leucine-enkephalin (LE), were chosen to compare the use of cyclodextrins and antibodies as possible affinity agents for improving their relative recovery across polycarbonate and polyethersulfone membranes during in vitro sampling. Cyclodextrins (CD) including β-CD, 2-hydroxypropyl-β-cyclodextrin (2HPβ-CD), and γ-CD gave improvements of relative recovery for both peptides of less than 2-fold as compared to controls. Comparisons of relative recovery between tyrosine-glycine-glycine, tyrosine, and phenylalanine using different cyclodextrins in the perfusion fluid were also obtained. Inclusion of an antibody against met-enkephalin in the microdialysis perfusion fluid resulted in relative recovery increases of up to 2.5-fold. These results show that using antibodies as affinity agents during microdialysis sampling may be more effective agents to improve the relative recovery of these opioid neuropeptides. PMID:18558138

Temporal Profiles Dissociate Regional Extracellular Ethanol versus Dopamine Concentrations

PubMed Central

2015-01-01

In vivo monitoring of dopamine via microdialysis has demonstrated that acute, systemic ethanol increases extracellular dopamine in regions innervated by dopaminergic neurons originating in the ventral tegmental area and substantia nigra. Simultaneous measurement of dialysate dopamine and ethanol allows comparison of the time courses of their extracellular concentrations. Early studies demonstrated dissociations between the time courses of brain ethanol concentrations and dopaminergic responses in the nucleus accumbens (NAc) elicited by acute ethanol administration. Both brain ethanol and extracellular dopamine levels peak during the first 5 min following systemic ethanol administration, but the dopamine response returns to baseline while brain ethanol concentrations remain elevated. Post hoc analyses examined ratios of the dopamine response (represented as a percent above baseline) to tissue concentrations of ethanol at different time points within the first 25–30 min in the prefrontal cortex, NAc core and shell, and dorsomedial striatum following a single intravenous infusion of ethanol (1 g/kg). The temporal patterns of these “response ratios” differed across brain regions, possibly due to regional differences in the mechanisms underlying the decline of the dopamine signal associated with acute intravenous ethanol administration and/or to the differential effects of acute ethanol on the properties of subpopulations of midbrain dopamine neurons. This Review draws on neurochemical, physiological, and molecular studies to summarize the effects of acute ethanol administration on dopamine activity in the prefrontal cortex and striatal regions, to explore the potential reasons for the regional differences observed in the decline of ethanol-induced dopamine signals, and to suggest directions for future research. PMID:25537116

Using cholinergic M1 receptor positive allosteric modulators to improve memory via enhancement of brain cholinergic communication.

PubMed

Chambon, Caroline; Jatzke, Claudia; Wegener, Nico; Gravius, Andreas; Danysz, Wojciech

2012-12-15

Benzylquinolone carboxylic acid (BQCA) is a recently described cholinergic muscarinic M(1) receptor positive allosteric modulator having potential as cognitive enhancer in dementia. The present study focused on the characterisation of BQCA's mode of action in relation to positive effects on memory and side-effects in an animal model. To get insight into this mode of action, in vitro receptor potency/left shift experiments in cells stably expressing the rat's M(1) receptor were performed. They revealed an inflection point value of BQCA corresponding to 306nM, and potentiation of the agonist response up to 47-fold in presence of 10μM of BQCA. In vivo, brain microdialysis showed a maximal brain level of 270nM, 40min after i.p. administration at 10mg/kg. Based on in vitro data obtained with this dose, it can be concluded that BQCA reaches brain levels which should potentiate the agonist response about 4-fold. Behavioural data confirmed that BQCA used at 10mg/kg attenuated scopolamine-induced memory deficit in a spontaneous alternation task. Moreover, BQCA showed no side effect at 10mg/kg and above in spontaneous locomotion and salivation tests. The profile of BQCA observed in the present study displays a clear advantage over the M(1)-M(3) agonist cevimeline. The present data show the therapeutic potential of the M(1) receptor positive allosteric modulator BQCA for the treatment of memory deficits observed in Alzheimer's disease. Copyright © 2012. Published by Elsevier B.V.

Microdialysis as a way to measure antibiotics concentration in tissues.

PubMed

Marchand, Sandrine; Chauzy, Alexia; Dahyot-Fizelier, Claire; Couet, William

2016-09-01

As for all other drugs, antibiotics must reach their pharmacodynamic target in order to exert their effect, but because infection may occur in various tissues the distribution of antibiotics has always been of particular concern. In this article, we will first critically review the various methodologies available to study antibiotics tissue distribution, including microdialysis, secondly we will show how basic pharmacokinetic concepts may help to predict or interpret antibiotics tissue distribution and third we will address the question of linking antibiotics tissue distribution with their antimicrobial effect, using modern pharmacokinetic-pharmacodynamic methods. Copyright © 2016 Elsevier Ltd. All rights reserved.

Targeted Deletion of Kynurenine 3-Monooxygenase in Mice

PubMed Central

Giorgini, Flaviano; Huang, Shao-Yi; Sathyasaikumar, Korrapati V.; Notarangelo, Francesca M.; Thomas, Marian A. R.; Tararina, Margarita; Wu, Hui-Qiu; Schwarcz, Robert; Muchowski, Paul J.

2013-01-01

Kynurenine 3-monooxygenase (KMO), a pivotal enzyme in the kynurenine pathway (KP) of tryptophan degradation, has been suggested to play a major role in physiological and pathological events involving bioactive KP metabolites. To explore this role in greater detail, we generated mice with a targeted genetic disruption of Kmo and present here the first biochemical and neurochemical characterization of these mutant animals. Kmo−/− mice lacked KMO activity but showed no obvious abnormalities in the activity of four additional KP enzymes tested. As expected, Kmo−/− mice showed substantial reductions in the levels of its enzymatic product, 3-hydroxykynurenine, in liver, brain, and plasma. Compared with wild-type animals, the levels of the downstream metabolite quinolinic acid were also greatly decreased in liver and plasma of the mutant mice but surprisingly were only slightly reduced (by ∼20%) in the brain. The levels of three other KP metabolites: kynurenine, kynurenic acid, and anthranilic acid, were substantially, but differentially, elevated in the liver, brain, and plasma of Kmo−/− mice, whereas the liver and brain content of the major end product of the enzymatic cascade, NAD+, did not differ between Kmo−/− and wild-type animals. When assessed by in vivo microdialysis, extracellular kynurenic acid levels were found to be significantly elevated in the brains of Kmo−/− mice. Taken together, these results provide further evidence that KMO plays a key regulatory role in the KP and indicate that Kmo−/− mice will be useful for studying tissue-specific functions of individual KP metabolites in health and disease. PMID:24189070

Regional muscle tissue saturation is an indicator of global inadequate circulation during cardiopulmonary bypass: a randomized porcine study using muscle, intestinal and brain tissue metabolomics.

PubMed

Thomassen, Sisse Anette; Kjærgaard, Benedict; Sørensen, Preben; Andreasen, Jan Jesper; Larsson, Anders; Rasmussen, Bodil Steen

2017-04-01

Muscle tissue saturation (StO 2 ) measured with near-infrared spectroscopy has generally been considered a measurement of the tissue microcirculatory condition. However, we hypothesized that StO 2 could be more regarded as a fast and reliable measure of global than of regional circulatory adequacy and tested this with muscle, intestinal and brain metabolomics at normal and two levels of low cardiopulmonary bypass blood flow rates in a porcine model. Twelve 80 kg pigs were connected to normothermic cardiopulmonary bypass with a blood flow of 60 mL/kg/min for one hour, reduced randomly to 47.5 mL/kg/min (Group I) or 35 mL/kg/min (Group II) for one hour followed by one hour of 60 mL/kg/min in both groups. Regional StO 2 was measured continuously above the musculus gracilis (non-cannulated leg). Metabolomics were obtained by brain tissue oxygen monitoring system (Licox) measurements of the brain and microdialysis perfusate from the muscle, intestinal mucosa and brain. A non-parametric statistical method was used. The systemic parameters showed profound systemic ischaemia during low CPB blood flow. StO 2 did not change markedly in Group I, but in Group II, StO 2 decreased immediately when blood flow was reduced and, furthermore, was not restored despite blood flow being normalized. Changes in the metabolomics from the muscle, colon and brain followed the changes in StO 2 . We found, in this experimental cardiopulmonary bypass model, that StO 2 reacted rapidly when the systemic circulation became inadequate and, furthermore, reliably indicate insufficient global tissue perfusion even when the systemic circulation was restored after a period of systemic hypoperfusion.

Neuronal LRP1 regulates glucose metabolism and insulin signaling in the brain.

PubMed

Liu, Chia-Chen; Hu, Jin; Tsai, Chih-Wei; Yue, Mei; Melrose, Heather L; Kanekiyo, Takahisa; Bu, Guojun

2015-04-08

Alzheimer's disease (AD) is a neurological disorder characterized by profound memory loss and progressive dementia. Accumulating evidence suggests that Type 2 diabetes mellitus, a metabolic disorder characterized by insulin resistance and glucose intolerance, significantly increases the risk for developing AD. Whereas amyloid-β (Aβ) deposition and neurofibrillary tangles are major histological hallmarks of AD, impairment of cerebral glucose metabolism precedes these pathological changes during the early stage of AD and likely triggers or exacerbates AD pathology. However, the mechanisms linking disturbed insulin signaling/glucose metabolism and AD pathogenesis remain unclear. The low-density lipoprotein receptor-related protein 1 (LRP1), a major apolipoprotein E receptor, plays critical roles in lipoprotein metabolism, synaptic maintenance, and clearance of Aβ in the brain. Here, we demonstrate that LRP1 interacts with the insulin receptor β in the brain and regulates insulin signaling and glucose uptake. LRP1 deficiency in neurons leads to impaired insulin signaling as well as reduced levels of glucose transporters GLUT3 and GLUT4. Consequently, glucose uptake is reduced. By using an in vivo microdialysis technique sampling brain glucose concentration in freely moving mice, we further show that LRP1 deficiency in conditional knock-out mice resulted in glucose intolerance in the brain. We also found that hyperglycemia suppresses LRP1 expression, which further exacerbates insulin resistance, glucose intolerance, and AD pathology. As loss of LRP1 expression is seen in AD brains, our study provides novel insights into insulin resistance in AD. Our work also establishes new targets that can be explored for AD prevention or therapy. Copyright © 2015 the authors 0270-6474/15/355851-09$15.00/0.

Low dose naltrexone administration in morphine dependent rats attenuates withdrawal-induced norepinephrine efflux in forebrain.

PubMed

Van Bockstaele, Elisabeth J; Qian, Yaping; Sterling, Robert C; Page, Michelle E

2008-05-15

The administration of low dose opioid antagonists has been explored as a potential means of detoxification in opiate dependence. Previous results from our laboratory have shown that concurrent administration of low dose naltrexone in the drinking water of rats implanted with subcutaneous morphine pellets attenuates behavioral and biochemical signs of withdrawal in brainstem noradrenergic nuclei. Noradrenergic projections originating from the nucleus tractus solitarius (NTS) and the locus coeruleus (LC) have previously been shown to be important neural substrates involved in the somatic expression of opiate withdrawal. The hypothesis that low dose naltrexone treatment attenuates noradrenergic hyperactivity typically associated with opiate withdrawal was examined in the present study by assessing norepinephrine tissue content and norepinephrine efflux using in vivo microdialysis coupled to high performance liquid chromatography (HPLC) with electrochemical detection (ED). The frontal cortex (FC), amygdala, bed nucleus of the stria terminalis (BNST) and cerebellum were analyzed for tissue content of norepinephrine following withdrawal in morphine dependent rats. Naltrexone-precipitated withdrawal elicited a significant decrease in tissue content of norepinephrine in the BNST and amygdala. This decrease was significantly attenuated in the BNST of rats that received low dose naltrexone pre-treatment compared to controls. No significant difference was observed in the other brain regions examined. In a separate group of rats, norepinephrine efflux was assessed with in vivo microdialysis in the BNST or the FC of morphine dependent rats or placebo treated rats subjected to naltrexone-precipitated withdrawal that received either naltrexone in their drinking water (5 mg/L) or unadulterated water. Following baseline dialysate collection, withdrawal was precipitated by injection of naltrexone and sample collection continued for an additional 4 h. At the end of the experiment, animals were transcardially perfused and the brains were removed for verification of probe placement. Low dose naltrexone pre-treatment significantly attenuated withdrawal-induced increases of extracellular norepinephrine in the BNST, with a smaller effect in the FC. These findings suggest that alterations in norepinephrine release associated with withdrawal may be attenuated in forebrain targets of noradrenergic brainstem neurons that may underlie reduced behavioral signs of withdrawal following low dose naltrexone administration.

[Amino acid changes following intraperitoneal administration of Tityus zulianus scorpion venom in mice. Study with subcutaneous microdialysis and capillary electrophoresis].

PubMed

Páez, Ximena; Mazzei-Dávila, Carmen Amalia; Quiñonez, Belkis; D'Suze, Gina; Hernández, Luis

2003-12-01

Scorpion human envenoming is a public health hazard in the southwest of Venezuela. Tityus zulianus is one of the scorpion species whose venom causes lung edema and cardiac failure in children. These occasionally deadly manifestations have been attributed to a massive sympathetic discharge. The intraperitoneal administration of T. zulianus venom (20 micrograms/g mouse) to anesthetized mice during subcutaneous microdialysis caused increased secretions, dyspnea, seizures and death between 30 min to 2 h. Seven amino acids were analyzed by capillary electrophoresis with laser induced fluorescence detection (CE-LIFD) in the collected samples before and after the venom administration. We found an increase of arginine (39%), phenylalanine (40%) and glutamate (94%), with no changes in valine, serine and aspartate, changes were significant when the injection of venom and vehicle were compared and before vs after venom injection. Further investigation is needed to know if the observed changes could be related to the molecular mechanisms of the venom or some of its components and therefore with the envenoming symptoms. To our knowledge, this is the first report with subcutaneous microdialysis and CE-LIFD coupling in scorpion envenomation studies in vivo, in mice.

Involvement of intracellular Zn2+ signaling in LTP at perforant pathway-CA1 pyramidal cell synapse.

PubMed

Tamano, Haruna; Nishio, Ryusuke; Takeda, Atsushi

2017-07-01

Physiological significance of synaptic Zn 2+ signaling was examined at perforant pathway-CA1 pyramidal cell synapses. In vivo long-term potentiation (LTP) at perforant pathway-CA1 pyramidal cell synapses was induced using a recording electrode attached to a microdialysis probe and the recording region was locally perfused with artificial cerebrospinal fluid (ACSF) via the microdialysis probe. Perforant pathway LTP was not attenuated under perfusion with CaEDTA (10 mM), an extracellular Zn 2+ chelator, but attenuated under perfusion with ZnAF-2DA (50 μM), an intracellular Zn 2+ chelator, suggesting that intracellular Zn 2+ signaling is required for perforant pathway LTP. Even in rat brain slices bathed in CaEDTA in ACSF, intracellular Zn 2+ level, which was measured with intracellular ZnAF-2, was increased in the stratum lacunosum-moleculare where perforant pathway-CA1 pyramidal cell synapses were contained after tetanic stimulation. These results suggest that intracellular Zn 2+ signaling, which originates in internal stores/proteins, is involved in LTP at perforant pathway-CA1 pyramidal cell synapses. Because the influx of extracellular Zn 2+ , which originates in presynaptic Zn 2+ release, is involved in LTP at Schaffer collateral-CA1 pyramidal cell synapses, synapse-dependent Zn 2+ dynamics may be involved in plasticity of postsynaptic CA1 pyramidal cells. © 2017 Wiley Periodicals, Inc.

Characterization of peripheral-compartment kinetics of antibiotics by in vivo microdialysis in humans.

PubMed Central

Müller, M; Haag, O; Burgdorff, T; Georgopoulos, A; Weninger, W; Jansen, B; Stanek, G; Pehamberger, H; Agneter, E; Eichler, H G

1996-01-01

The calculation of pharmacokinetic/pharmacodynamic surrogates from concentrations in serum has been shown to yield important information for the evaluation of antibiotic regimens. Calculations based on concentrations in serum, however, may not necessarily be appropriate for peripheral-compartment infections. The aim of the present study was to apply the microdialysis technique for the study of the peripheral-compartment pharmacokinetics of select antibiotics in humans. Microdialysis probes were inserted into the skeletal muscle and adipose tissue of healthy volunteers and into inflamed and noninflamed dermis of patients with cellulitis. Thereafter, volunteers received either cefodizime (2,000 mg as an intravenous bolus; n = 6), cefpirome (2,000 mg as an intravenous bolus; n = 6), fleroxacin (400 mg orally n = 6), or dirithromycin (250 mg orally; n = 4); the patients received phenoxymethylpenicillin (4.5 x 10(6) U orally; n = 3). Complete concentration-versus-time profiles for serum and tissues could be obtained for all compounds. Major pharmacokinetic parameters (elimination half-life, peak concentration in serum, time to peak concentration, area under the concentration-time curve [AUC], and AUC/MIC ratio) were calculated for tissues. For cefodizime and cefpirome, the AUCtissue/AUCserum ratios were 0.12 to 0.35 and 1.20 to 1.79, respectively. The AUCtissue/AUCserum ratios were 0.34 to 0.38 for fleroxacin and 0.42 to 0.49 for dirithromycin. There was no visible difference in the time course of phenoxymethylpenicillin in inflamed and noninflamed dermis. We demonstrated, by means of microdialysis, that the concept of pharmacokinetic/pharmacodynamic surrogate markers for evaluation of antibiotic regimens originally developed for serum pharmacokinetics can be extended to peripheral-tissue pharmacokinetics. This novel information may be useful for the rational development of dosage schedules and may improve predictions regarding therapeutic outcome. PMID:9124826

Anandamide enhances extracellular levels of adenosine and induces sleep: an in vivo microdialysis study.

PubMed

Murillo-Rodriguez, Eric; Blanco-Centurion, Carlos; Sanchez, Cristina; Piomelli, Daniele; Shiromani, Priyattam J

2003-12-15

The principal component of marijuana, delta-9-tetrahydrocannabinol increases sleep in humans. Endogenous cannabinoids, such as N-arachidonoylethanolamine (anandamide), also increase sleep. However, the mechanism by which these molecules promote sleep is not known but might involve a sleep-inducing molecule such as adenosine. Microdialysis samples were collected from the basal forebrain in order to detect levels of adenosine before and after injection of anandamide. Rats were implanted for sleep studies, and a cannula was placed in the basal forebrain to collect microdialysis samples. Samples were analyzed using high-performance liquid chromatography. Basic neuroscience research laboratory. Three-month-old male F344 rats. At the start of the lights-on period, animals received systemic injections of dimethyl sulfoxide (vehicle), anandamide, SR141716A (cannabinoid receptor 1 [CB1] antagonist), or SR141716A and anandamide. One hour after injections, microdialysis samples were collected (5 microL) from the basal forebrain every hour over a 20-minute period for 5 hours. The samples were immediately analyzed via high-performance liquid chromatography for adenosine levels. Sleep was also recorded continuously over the same period. Anandamide increased adenosine levels compared to vehicle controls with the peak levels being reached during the third hour after drug injection. There was a significant increase in slow-wave sleep during the third hour. The induction in sleep and the rise in adenosine were blocked by the CB1-receptor antagonist, SR141716A. Anandamide increased adenosine levels in the basal forebrain and also increased sleep. The soporific effects of anandamide were mediated by the CB1 receptor, since the effects were blocked by the CB1-receptor antagonist. These findings identify a potential therapeutic use of endocannabinoids to induce sleep in conditions where sleep may be severely attenuated.

Electrochemical sensing of total antioxidant capacity and polyphenol content in wine samples using amperometry online-coupled with microdialysis.

PubMed

Jakubec, Petr; Bancirova, Martina; Halouzka, Vladimir; Lojek, Antonin; Ciz, Milan; Denev, Petko; Cibicek, Norbert; Vacek, Jan; Vostalova, Jitka; Ulrichova, Jitka; Hrbac, Jan

2012-08-15

This work describes the method for total antioxidant capacity (TAC) and/or total content of phenolics (TCP) analysis in wines using microdialysis online-coupled with amperometric detection using a carbon microfiber working electrode. The system was tested on 10 selected wine samples, and the results were compared with total reactive antioxidant potential (TRAP), oxygen radical absorbance capacity (ORAC), and chemiluminescent determination of total antioxidant capacity (CL-TAC) methods using Trolox and catechin as standards. Microdialysis online-coupled with amperometric detection gives similar results to the widely used cyclic voltammetry methodology and closely correlates with ORAC and TRAP. The problem of electrode fouling is overcome by the introduction of an electrochemical cleaning step (1-2 min at the potential of 0 V vs Ag/AgCl). Such a procedure is sufficient to fully regenerate the electrode response for both red and white wine samples as well as catechin/Trolox standards. The appropriate size of microdialysis probes enables easy automation of the electrochemical TAC/TCP measurement using 96-well microtitration plates.

Comparison of different amino acid derivatives and analysis of rat brain microdialysates by liquid chromatography tandem mass spectrometry.

PubMed

Uutela, Päivi; Ketola, Raimo A; Piepponen, Petteri; Kostiainen, Risto

2009-02-09

The efficiencies of three derivatisation reagents that react with either the amine (9-fluorenylmethyl chloroformate (FMOC)) or the carboxylic acid group (butanol) of amino acid or with both types of functional groups (propyl chloroformate) were compared in the analysis of amino acids by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS). Separation of 20 amino acids derivatised with these three reagents was studied on reversed-phase chromatography. Linearity, repeatability and limits of detection of the LC-ESI-MS/MS method were determined by analysing FMOC-, butanol- and propyl chloroformate-derivatised lysine, beta-aminobutyric acid, threonine and glutamic acid. The limits of detection for the derivatised amino acids (7.5-75fmol) were as much as 2-60 times lower than those of the corresponding underivatised molecules. The best linearity was observed for amino acids derivatised with propyl chloroformate or butanol (r(2)=0.996-0.999, range=100-8500nmolL(-1)). Propyl chloroformate was the best suited of the reagents tested for the analysis of amino acids with LC-MS/MS and was used for the analysis of amino acids in rat brain microdialysis samples.

A new minimal-stress freely-moving rat model for preclinical studies on intranasal administration of CNS drugs.

PubMed

Stevens, Jasper; Suidgeest, Ernst; van der Graaf, Piet Hein; Danhof, Meindert; de Lange, Elizabeth C M

2009-08-01

To develop a new minimal-stress model for intranasal administration in freely moving rats and to evaluate in this model the brain distribution of acetaminophen following intranasal versus intravenous administration. Male Wistar rats received one intranasal cannula, an intra-cerebral microdialysis probe, and two blood cannulas for drug administration and serial blood sampling respectively. To evaluate this novel model, the following experiments were conducted. 1) Evans Blue was administered to verify the selectivity of intranasal exposure. 2) During a 1 min infusion 10, 20, or 40 microl saline was administered intranasally or 250 microl intravenously. Corticosterone plasma concentrations over time were compared as biomarkers for stress. 3) 200 microg of the model drug acetaminophen was given in identical setup and plasma, and brain pharmacokinetics were determined. In 96% of the rats, only the targeted nasal cavity was deeply colored. Corticosterone plasma concentrations were not influenced, neither by route nor volume of administration. Pharmacokinetics of acetaminophen were identical after intravenous and intranasal administration, although the Cmax in microdialysates was reached a little earlier following intravenous administration. A new minimal-stress model for intranasal administration in freely moving rats has been successfully developed and allows direct comparison with intravenous administration.

Effect of perinatal asphyxia and carbamazepine treatment on cortical dopamine and DOPAC levels.

PubMed

López-Pérez, Silvia J; Morales-Villagrán, Alberto; Medina-Ceja, Laura

2015-02-13

One of the most important manifestations of perinatal asphyxia is the occurrence of seizures, which are treated with antiepileptic drugs, such as carbamazepine. These early seizures, combined with pharmacological treatments, may influence the development of dopaminergic neurotransmission in the frontal cortex. This study aimed to determine the extracellular levels of dopamine and its main metabolite DOPAC in 30-day-old rats that had been asphyxiated for 45 min in a low (8%) oxygen chamber at a perinatal age and treated with daily doses of carbamazepine. Quantifications were performed using microdialysis coupled to a high-performance liquid chromatography (HPLC) system in basal conditions and following the use of the chemical stimulus. Significant decreases in basal and stimulated extracellular dopamine and DOPAC content were observed in the frontal cortex of the asphyxiated group, and these decreases were partially recovered in the animals administered daily doses of carbamazepine. Greater basal dopamine concentrations were also observed as an independent effect of carbamazepine. Perinatal asphyxia plus carbamazepine affects extracellular levels of dopamine and DOPAC in the frontal cortex and stimulated the release of dopamine, which provides evidence for the altered availability of dopamine in cortical brain areas during brain development.

Microsomal metabolism of calycosin, formononetin and drug-drug interactions by dynamic microdialysis sampling and HPLC-DAD-MS analysis.

PubMed

Wen, Xiao-Dong; Qi, Lian-Wen; Li, Bin; Li, Ping; Yi, Ling; Wang, Ya-Qiong; Liu, E-Hu; Yang, Xiao-Lin

2009-08-15

A dynamic microdialysis sampling method with liquid chromatography-diode array detection and time-of-flight mass spectrometry (LC-DAD-TOF/MS) analysis was developed to investigate rat microsomal metabolisms of calycosin and formononetin, and their drug-drug interactions. Two hydroxylated metabolites from calycosin, and three hydroxylated or 4'-O-demethylated derivatives from formononetin were detected and identified after co-incubation with microsomes. Calibration curves offered linear ranges of two orders of magnitude with r(2)>0.999 for calycosin, formononetin and daidzein. The quantitative LC method provides a range of 0.028-0.034microg/mL for limits of detection, overall precision less than 5% and accuracy less than 3% by RSD. Besides, calycosin and formononetin were found to produce the depressive effect on the CYP450 enzyme reaction, and inhibit phase I enzyme reaction of each other when they are concurrent. Dynamic microdialysis sampling with LC-DAD-TOF/MS analysis developed in this work is a powerful tool for in vitro metabolism studies of drugs and metabolic interactions.

Effect of barrier perturbation on cutaneous penetration of salicylic acid in hairless rats: in vivo pharmacokinetics using microdialysis and non-invasive quantification of barrier function.

PubMed

Benfeldt, E; Serup, J

1999-09-01

The penetration of topically applied drugs is altered in diseased or barrier-damaged skin. We used microdialysis in the dermis to measure salicylic acid (SA) penetration in hairless rats following application to normal (unmodified) skin (n = 11) or skin with perturbed barrier function from (1) tape-stripping (n = 5), (2) sodium lauryl sulphate (SLS) 2% for 24 h (n = 3) or (3) delipidization by acetone (n = 4). Prior to the experiment, transepidermal water loss (TEWL) and erythema were measured. Two microdialysis probes were inserted into the dermis on the side of the trunk and 5% SA in ethanol was applied in a chamber overlying the probes. Microdialysis sampling was continued for 4 h, followed by measurements of probe depth by ultrasound scanning. SA was detectable in all samples and rapidly increasing up to 130 min. Microdialysates collected between 80 and 200 min showed mean SA concentrations of 3 microg/ml in unmodified and acetone-treated skin, whereas mean SA concentrations were 280 microg/ml in SLS-pretreated skin and 530 microg/ml in tape-stripped skin (P < 0.001). The penetration of SA correlated with barrier perturbation measured by TEWL (P < 0.001) and erythema (P < 0.001). A correlation between dermal probe depth and SA concentration was found in unmodified skin (P = 0.04). Microdialysis sampling in anatomical regions remote from the dosed site excluded the possibility that SA levels measured were due to systemic absorption. Microdialysis sampling of cutaneous penetration was highly reproducible. Impaired barrier function, caused by irritant dermatitis or tape stripping, resulted in an 80- to 170-fold increase in the drug level in the dermis. This dramatic increase in drug penetration could be relevant to humans, in particular to topical treatment of skin diseases and to occupational toxicology.

Studies on the neuroprotective action of kynurenine mono-oxygenase inhibitors in post-ischemic brain damage.

PubMed

Moroni, Flavio; Carpenedo, Raffaella; Cozzi, Andrea; Meli, Elena; Chiarugi, Alberto; Pellegrini-Giampietro, Domenico E

2003-01-01

Kynurenine 3-mono-oxygenase (KMO) inhibitors facilitate kynurenic acid (KYNA) neosynthesis and reduce the formation of 3OH-kynurenine (3-HK) and quinolinic acid (QUIN). They also attenuate post-ischemic brain damage and decrease glutamate (Glu) content in brain extracellular spaces. To investigate KMO mechanism(s) of neuroprotection, we performed experiments in gerbils subjected to bilateral carotid occlusion and in organotypic rat hippocampal slice cultures exposed to oxygen and glucose deprivation (OGD). In gerbils, direct application of KYNA (100 nM, through reverse microdialysis in the hippocampus) completely prevented the increase in Glu output induced by transient (5 min) occlusion of the carotids. In rat hippocampal slices exposed for 30 min to OGD, KMO inhibitors (m-nitrobenzoyl)-alanine (mNBA, 30-100 microM) or 3,4-dimethoxy-[-N-4-(nitrophenyl)thiazol-2yl]-benzenesulfonamide (Ro 61-8048, 1-10 microM) reduced post-ischemic neuronal death and increased KYNA concentrations in the incubation medium. KYNA may antagonize glycineb or alpha7 nicotinic acetylcholine receptors but the concentrations in the incubation medium never reached values that could efficiently antagonize receptor function. On the contrary, 3-HK (1-10 microM) added to slices exposed to OGD in the presence of KMO inhibitors completely prevented the neuroprotective effects of the inhibitors. Our findings suggest that KMO inhibitors reduce OGD-induced pyramidal cell death by decreasing 3-HK (and possibly QUIN) synthesis.

Monoamine reuptake inhibition and mood-enhancing potential of a specified oregano extract.

PubMed

Mechan, Annis O; Fowler, Ann; Seifert, Nicole; Rieger, Henry; Wöhrle, Tina; Etheve, Stéphane; Wyss, Adrian; Schüler, Göde; Colletto, Biagio; Kilpert, Claus; Aston, James; Elliott, J Martin; Goralczyk, Regina; Mohajeri, M Hasan

2011-04-01

A healthy, balanced diet is essential for both physical and mental well-being. Such a diet must include an adequate intake of micronutrients, essential fatty acids, amino acids and antioxidants. The monoamine neurotransmitters, serotonin, dopamine and noradrenaline, are derived from dietary amino acids and are involved in the modulation of mood, anxiety, cognition, sleep regulation and appetite. The capacity of nutritional interventions to elevate brain monoamine concentrations and, as a consequence, with the potential for mood enhancement, has not been extensively evaluated. The present study investigated an extract from oregano leaves, with a specified range of active constituents, identified via an unbiased, high-throughput screening programme. The oregano extract was demonstrated to inhibit the reuptake and degradation of the monoamine neurotransmitters in a dose-dependent manner, and microdialysis experiments in rats revealed an elevation of extracellular serotonin levels in the brain. Furthermore, following administration of oregano extract, behavioural responses were observed in mice that parallel the beneficial effects exhibited by monoamine-enhancing compounds when used in human subjects. In conclusion, these data show that an extract prepared from leaves of oregano, a major constituent of the Mediterranean diet, is brain-active, with moderate triple reuptake inhibitory activity, and exhibits positive behavioural effects in animal models. We postulate that such an extract may be effective in enhancing mental well-being in humans.

The serotonin-dopamine interaction measured with positron emission tomography (PET) and C-11 raclopride in normal human subjects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, G.S.; Dewey, S.L.; Logan, J.

1994-05-01

Our previous studies have shown that the interaction between serotonin and dopamine can be measured with C-11 raclopride and PET in the baboon brain. A series of studies was undertaken to extend dim findings to the normal human brain. PET studies were conducted in male control subjects (n=8) using the CTI 931 tomograph. Two C-11 raclopride scans were performed, prior to and 180 minutes following administration of the selective serotonin releasing agent, fenfluramine (60mg/PO). The neuroendocrine response to fenfluramine challenge is commonly used in psychiatric research as an index of serotonin activity. The C-11 raclopride data were analyzed with themore » distribution volume method. For the group of subjects, an increase was observed in the striatum to cerebellum ratio (specific to non-specific binding ratio), in excess of the test-retest variability of the ligand. Variability in response was observed across subjects. These results are consistent with our previous findings in the baboon that citalopram administration increased C-11 raclopride binding, consistent with a decrease in endogenous dopamine. In vivo microdialysis studies in freely moving rats confirmed that citalopram produces a time-dependent decrease in extracellular dopamine levels, consistent with the PET results. In vivo PET studies of the serotonin-dopamine interaction are relevant to the evaluation of etiologic and therapeutic mechanisms in schizophrenia and affective disorder.« less

Creatine supplementation reduces sleep need and homeostatic sleep pressure in rats.

PubMed

Dworak, Markus; Kim, Tae; Mccarley, Robert W; Basheer, Radhika

2017-06-01

Sleep has been postulated to promote brain energy restoration. It is as yet unknown if increasing the energy availability within the brain reduces sleep need. The guanidine amino acid creatine (Cr) is a well-known energy booster in cellular energy homeostasis. Oral Cr-monohydrate supplementation (CS) increases exercise performance and has been shown to have substantial effects on cognitive performance, neuroprotection and circadian rhythms. The effect of CS on cellular high-energy molecules and sleep-wake behaviour is unclear. Here, we examined the sleep-wake behaviour and brain energy metabolism before and after 4-week-long oral administration of CS in the rat. CS decreased total sleep time and non-rapid eye movement (NREM) sleep significantly during the light (inactive) but not during the dark (active) period. NREM sleep and NREM delta activity were decreased significantly in CS rats after 6 h of sleep deprivation. Biochemical analysis of brain energy metabolites showed a tendency to increase in phosphocreatine after CS, while cellular adenosine triphosphate (ATP) level decreased. Microdialysis analysis showed that the sleep deprivation-induced increase in extracellular adenosine was attenuated after CS. These results suggest that CS reduces sleep need and homeostatic sleep pressure in rats, thereby indicating its potential in the treatment of sleep-related disorders. © 2017 European Sleep Research Society.

Effects of methiothepin on changes in brain serotonin release induced by repeated administration of high doses of anorectic serotoninergic drugs

NASA Technical Reports Server (NTRS)

Gardier, A. M.; Kaakkola, S.; Erfurth, A.; Wurtman, R. J.

1992-01-01

We previously observed, using in vivo microdialysis, that the potassium-evoked release of frontocortical serotonin (5-HT) is suppressed after rats receive high doses (30 mg/kg, i.p., daily for 3 days) of fluoxetine, a selective blocker of 5-HT reuptake. We now describe similar impairments in 5-HT release after repeated administration of two other 5-HT uptake blockers, zimelidine and sertraline (both at 20 mg/kg, i.p. for 3 days) as well as after dexfenfluramine (7.5 mg/kg, i.p. daily for 3 days), a drug which both releases 5-HT and blocks its reuptake. Doses of these indirect serotonin agonists were about 4-6 times the drug's ED50 in producing anorexia, a serotonin-related behavior. In addition, methiothepin (20 microM), a non-selective receptor antagonist, locally perfused through the dialysis probe 24 h after the last drug injection, enhanced K(+)-evoked release of 5-HT at serotoninergic nerve terminals markedly in control rats and slightly in rats treated with high doses of dexfenfluramine or fluoxetine. On the other hand, pretreatment with methiothepin (10 mg/kg, i.p.) one hour before each of the daily doses of fluoxetine or dexfenfluramine given for 3 days, totally prevented the decrease in basal and K(+)-evoked release of 5-HT. Finally, when methiothepin was injected systemically the day before the first of 3 daily injections of dexfenfluramine, it partially attenuated the long-term depletion of brain 5-HT and 5-HIAA levels induced by repeated administration of high doses of dexfenfluramine. These data suggest that drugs which bring about the prolonged blockade of 5-HT reuptake - such as dexfenfluramine and fluoxetine - can, by causing prolonged increases in intrasynaptic 5-HT levels as measured by in vivo microdialysis, produce receptor-mediated long-term changes in the processes controlling serotonin levels and dynamics.

Sex, Drugs and Gluttony: How the Brain Controls Motivated Behaviors

PubMed Central

Hull, Elaine M.

2011-01-01

Bart Hoebel has forged a view of an integrated neural network that mediates both natural rewards and drug use. He pioneered the use of microdialysis, and also effectively used electrical stimulation, lesions, microinjections, and immunohistochemistry. He found that feeding, stimulant drug administration, and electrical stimulation of the lateral hypothalamus (LH) all increased dopamine (DA) release in the nucleus accumbens (NAc). However, whereas DA in the NAc enhanced motivation, DA in the LH inhibited motivated behaviors. The Hull lab has pursued some of those ideas. We have suggested that serotonin (5-HT) in the perifornicalLH inhibits sexual behavior by inhibiting orexin/hypocretin neurons (OX/HCRT), which would otherwise excite neurons in the mesocorticolimbic DA tract. We have shown that DA release in the medial preoptic area (MPOA) is very important for male sexual behavior, and that testosterone, glutamate, nitric oxide (NO) and previous sexual experience promote MPOA DA release and mating. Future research should follow Bart Hoebel’s emphasis on neural systems and interactions among brain areas and neurotransmitters. PMID:21554895

Reinforcing and neurochemical effects of the "bath salts" constituents 3,4-methylenedioxypyrovalerone (MDPV) and 3,4-methylenedioxy-N-methylcathinone (methylone) in male rats.

PubMed

Schindler, Charles W; Thorndike, Eric B; Goldberg, Steven R; Lehner, Kurt R; Cozzi, Nicholas V; Brandt, Simon D; Baumann, Michael H

2016-05-01

3,4-Methylenedioxypyrovalerone (MDPV) and 3,4-methylenedioxy-N-methylcathinone (methylone) are synthetic drugs found in so-called "bath salts" products. Both drugs exert their effects by interacting with monoamine transporter proteins. MDPV is a potent uptake blocker at transporters for dopamine and norepinephrine while methylone is a non-selective releaser at transporters for dopamine, norepinephrine, and serotonin (5-HT). We hypothesized that prominent 5-HT-releasing actions of methylone would render this drug less reinforcing than MDPV. To test this hypothesis, we compared behavioral effects of MDPV and methylone using intravenous (i.v.) self-administration on a fixed-ratio 1 schedule in male rats. Additionally, neurochemical effects of the drugs were examined using in vivo microdialysis in nucleus accumbens, in a separate cohort of rats. MDPV self-administration (0.03 mg/kg/inj) was acquired rapidly and reached 40 infusions per session, similar to the effects of cocaine (0.5 mg/kg/inj), by the end of training. In contrast, methylone self-administration (0.3 and 0.5 mg/kg/inj) was acquired slowly, and response rates only reached 20 infusions per session by the end of training. In dose substitution studies, MDPV and cocaine displayed typical inverted U-shaped dose-effect functions, but methylone did not. In vivo microdialysis revealed that i.v. MDPV (0.1 and 0.3 mg/kg) increased extracellular dopamine while i.v. methylone (1 and 3 mg/kg) increased extracellular dopamine and 5-HT. Our findings support the hypothesis that elevations in extracellular 5-HT in the brain can dampen positive reinforcing effects of cathinone-type drugs. Nevertheless, MDPV and methylone are both self-administered by rats, suggesting these drugs possess significant abuse liability in humans.

Nicotine- and methamphetamine-induced dopamine release evaluated with in-vivo binding of radiolabelled raclopride to dopamine D2 receptors: comparison with in-vivo microdialysis data.

PubMed

Kim, Sang Eun; Han, Seung-Moo

2009-07-01

The effect of substances which alter extracellular dopamine (DA) concentration has been studied by measuring changes in the binding of radiolabelled raclopride, a DA D2 receptor ligand that is sensitive to endogenous DA. To better characterize the relationship between extracellular DA concentration and DA D2 receptor binding of raclopride, we compared the changes of extracellular DA concentration (measured using in-vivo microdialysis) and in-vivo [3H]raclopride binding induced by different doses of methamphetamine (Meth) and nicotine, drugs that enhance DA release with and without blocking DA transporters (DATs), respectively, in rat striatum. Nicotine elicited a modest increase of striatal extrasynaptic extracellular DA, while Meth produced a marked increase of striatal extrasynaptic DA in a dose-dependent manner. There was a close correlation between the decrease in [3H]raclopride in-vivo binding and the increase in extrasynaptic DA concentration induced by both nicotine (r2=0.95, p<0.001) and Meth (r2=0.98, p=0.001), supporting the usefulness of the radiolabelled raclopride-binding measurement for the non-invasive assessment of DA release following interventions in the living brain. However, the linear regression analysis revealed that the ratio of percent DA increase to percent [3H]raclopride binding reduction was 25-fold higher for Meth (34.8:1) than for nicotine (1.4:1). The apparent discrepancy in the extrasynaptic DA-[3H]raclopride binding relationship between the DA-enhancing drugs with and without DAT-blocking property indicates that the competition between endogenous DA and radiolabelled raclopride takes place at the intrasynaptic rather than extrasynaptic DA D2 receptors and reflects synaptic concentration of DA.

beta-Alanine elevates dopamine levels in the rat nucleus accumbens: antagonism by strychnine.

PubMed

Ericson, Mia; Clarke, Rhona B C; Chau, PeiPei; Adermark, Louise; Söderpalm, Bo

2010-04-01

Glycine receptors (GlyRs) in the nucleus accumbens (nAc) have recently been suggested to be involved in the reinforcing and dopamine-elevating properties of ethanol via a neuronal circuitry involving the VTA. Apart from ethanol, both glycine and taurine have the ability to modulate dopamine output via GlyRs in the same brain region. In the present study, we wanted to explore whether yet another endogenous ligand for the GlyR, beta-alanine, had similar effects. To this end, we monitored dopamine in the nAc by means of in vivo microdialysis and found that local perfusion of beta-alanine increased dopamine output. In line with previous observations investigating ethanol, glycine and taurine, the competitive GlyR antagonist strychnine completely blocked the dopamine elevation. The present results suggest that beta-alanine has the ability to modulate dopamine levels in the nAc via strychnine-sensitive GlyRs, and are consistent with previous studies suggesting the importance of this receptor for modulating dopamine output.

Microdialysis assessment of shock wave lithotripsy-induced renal injury.

PubMed

Brown, S A; Munver, R; Delvecchio, F C; Kuo, R L; Zhong, P; Preminger, G M

2000-09-01

Shock wave lithotripsy (SWL) is the primary treatment modality for managing the majority of symptomatic renal calculi. However, the fundamental mechanisms for stone fragmentation and the resultant morphologic changes that occur are not fully understood. Furthermore, a thorough understanding of the complex biologic pathways involved in SWL-induced renal injury does not exist at present. To elucidate the biologic processes involved in tissue injury after SWL, an animal model was designed to mimic the pathogenesis of high-energy SWL in humans. Juvenile female swine were anesthetized, and a midline laparotomy incision was performed to expose the right kidney. Using an introducer apparatus, a microdialysis probe was placed into the renal parenchyma of the right kidney lower pole and a tunnel was generated to exit the distal ends of the inlet and outlet tubing outside the body. After a 72-hour postoperative recovery period, SWL was performed to the lower pole renal region of the kidney, as a microdialysis pump continuously infused dialysate through the inlet tubing. Microdialysis fluids were collected during SWL, and lipid peroxidation, as measured by conjugated diene concentrations, was monitored. All microdialysis probes remained patent for a total of 2000 shock waves. A significant elevation in conjugated diene levels was observed in the SWL versus untreated kidneys after 1000 shock waves were administered (P <0.02). This animal model is unique in that it represents the first system for the real-time collection of renal interstitial fluids during SWL. Analysis of this fluid may provide insight into the physiologic mechanisms responsible for shock wave-induced renal injury.

Acute concomitant effects of MDMA binge dosing on extracellular 5-HT, locomotion and body temperature and the long-term effect on novel object discrimination in rats.

PubMed

Rodsiri, Ratchanee; Spicer, Clare; Green, A Richard; Marsden, Charles A; Fone, Kevin C F

2011-02-01

3,4-methylenedioxymethamphetamine (MDMA, ecstasy) produces an acute release of 5-HT in the brain, together with increased locomotion and hyperthermia. This study examined whether the acute functional changes of locomotor activity and body temperature are related to enhanced 5-HT release induced by MDMA. We concomitantly measured changes in extraneuronal 5-HT by in vivo brain microdialysis and used radiotelemetry to measure locomotion and body temperature to establish whether any positive correlations occur between these three parameters. 'Binge-type' repeated administration of low doses of MDMA (3 and 6 mg/kg given at 2-h intervals three times) were given to provide drug exposure similar to that experienced by recreational drug users. MDMA induced acute hyperactivity, changes in core body temperature (both hypothermia and hyperthermia) and elevation of hippocampal 5-HT overflow, all of which were dependent on the dose of MDMA administered. The change in locomotor activity and the magnitude of the hyperthermia appeared to be unrelated both to each other and to the magnitude of MDMA-induced 5-HT release. The study also found evidence of long-term disruption of novel object discrimination 2 weeks following "binge-type" repeated MDMA administration. MDMA-induced 5-HT release in the brain was not responsible for either the hyperthermia or increased locomotor activity that occurred. Since neither dose schedule of MDMA induced a neurotoxic loss of brain 5-HT 2 weeks after its administration, the impairment of recognition memory found in novel object discrimination probably results from other long-term changes yet to be established.

Levels of heroin and its metabolites in blood and brain extracellular fluid after i.v. heroin administration to freely moving rats

PubMed Central

Gottås, A; Øiestad, E L; Boix, F; Vindenes, V; Ripel, Å; Thaulow, C H; Mørland, J

2013-01-01

BACKGROUND AND PURPOSE Heroin, with low affinity for μ-opioid receptors, has been considered to act as a prodrug. In order to study the pharmacokinetics of heroin and its active metabolites after i.v. administration, we gave a bolus injection of heroin to rats and measured the concentration of heroin and its metabolites in blood and brain extracellular fluid (ECF). EXPERIMENTAL APPROACH After an i.v. bolus injection of heroin to freely moving Sprague–Dawley rats, the concentrations of heroin and metabolites in blood samples from the vena jugularis and in microdialysis samples from striatal brain ECF were measured by ultraperformance LC-MS/MS. KEY RESULTS Heroin levels decreased very fast, both in blood and brain ECF, and could not be detected after 18 and 10 min respectively. 6-Monoacetylmorphine (6-MAM) increased very rapidly, reaching its maximal concentrations after 2.0 and 4.3 min, respectively, and falling thereafter. Morphine increased very slowly, reaching its maximal levels, which were six times lower than the highest 6-MAM concentrations, after 12.6 and 21.3 min, with a very slow decline during the rest of the experiment and only surpassing 6-MAM levels at least 30 min after injection. CONCLUSIONS AND IMPLICATIONS After an i.v. heroin injection, 6-MAM was the predominant opioid present shortly after injection and during the first 30 min, not only in the blood but also in rat brain ECF. 6-MAM might therefore mediate most of the effects observed shortly after heroin intake, and this finding questions the general assumption that morphine is the main and most important metabolite of heroin. PMID:23865556

Prevention of Glutamate Accumulation and Upregulation of Phospho-Akt may Account for Neuroprotection Afforded by Bergamot Essential Oil against Brain Injury Induced by Focal Cerebral Ischemia in Rat.

PubMed

Amantea, Diana; Fratto, Vincenza; Maida, Simona; Rotiroti, Domenicantonio; Ragusa, Salvatore; Nappi, Giuseppe; Bagetta, Giacinto; Corasaniti, Maria Tiziana

2009-01-01

The effects of bergamot essential oil (BEO; Citrus bergamia, Risso) on brain damage caused by permanent focal cerebral ischemia in rat were investigated. Administration of BEO (0.1-0.5 ml/kg but not 1 ml/kg, given intraperitoneally 1 h before occlusion of the middle cerebral artery, MCAo) significantly reduced infarct size after 24 h permanent MCAo. The most effective dose (0.5 ml/kg) resulted in a significant reduction of infarct extension throughout the brain, especially in the medial striatum and the motor cortex as revealed by TTC staining of tissue slices. Microdialysis experiments show that BEO (0.5 ml/kg) did not affect basal amino acid levels, whereas it significantly reduced excitatory amino acid, namely aspartate and glutamate, efflux in the frontoparietal cortex typically observed following MCAo. Western blotting experiments demonstrated that these early effects were associated, 24 h after permanent MCAo, to a significant increase in the phosphorylation and activity of the prosurvival kinase, Akt. Indeed, BEO significantly enhanced the phosphorylation of the deleterious downstream kinase, GSK-3beta, whose activity is negatively regulated via phosphorylation by Akt.

Clonazepam increases in vivo striatal extracellular glucose in diabetic rats after glucose overload.

PubMed

Gomez, Rosane; Barros, Helena M T

2003-12-01

Hyperglycemia modulates brain function, including neuronal excitability, neurotransmitter release and behavioral changes. There may be connections between the GABAergic system, glucose sensing neurons and glucose in the neuronal environment that shed light on the mechanism by which GABA(A) agents influence depressive behavior in diabetic rats submitted to the forced swimming test. We aimed to investigate whether clonazepam (CNZ), a GABA(A) receptor positive modulator, modifies in vivo striatal extracellular glucose levels in diabetic rats under fasting condition or after oral glucose overload. Streptozotocin diabetic and nondiabetic rats were submitted to in vivo striatal microdialysis. Perfusate samples were collected at baseline, during fasting and following administration of CNZ (0.25 mg/kg) and oral glucose overload. Blood glucose and striatal extracellular glucose were measured simultaneously at several time points. Fasting striatal glucose levels were higher in diabetic than in nondiabetic rats and the differences between these animals were maintained after glucose overload. The increases in extracellular striatal glucose after glucose overload were around 40% and blood to brain transference was decreased in diabetics. CNZ treatment paradoxically increased striatal glucose after glucose overload in diabetic rats, which may mark the dysfunction in brain glucose homeostasis.

A stereotaxic atlas of the forebrain of the bank vole (Clethrionomys glareolus).

PubMed

Vandebroek, I; Bouche, K; D'Herde, K; Caemaert, J; Roels, F; Odberg, F O

1999-04-01

In this article part of the forebrain of the bank vole (Clethrionomys glareolus) is presented in stereotaxic coordinates. The stereotaxic procedure was performed as follows. With the vole's head mounted in a stereotaxic adaptor, internal reference tracks were made with a 0.5-mm diameter microdialysis cannula and India ink, 2 mm in front and 2.6 mm behind the skull landmark bregma. Brains were fixed for 72 h in 4% commercial formaldehyde in sodiumcacodylate buffer containing 1% CaCl2. To determine shrinkage they were weighed before and after fixation. After embedding in paraffin they were sectioned at 25 microm and stained with Nissl. Photomicrographs were taken from the brain of one animal while its frontal (antero-posterior) coordinates of five neural structures were compared with those of 12 other voles. Variability was also checked in lateral and vertical directions at frontal level -1.0 mm (relative to bregma). The results show that the distance between the two skull landmarks bregma and lambda correlates significantly and negatively with the antero-posterior position of each of the brain areas. On the basis of these results an equation is proposed to improve accuracy in locating neural structures that deviate due to biological variability.

The influence of hyperthermia on intracranial pressure, cerebral oximetry and cerebral metabolism in traumatic brain injury

PubMed Central

Nyholm, Lena; Howells, Tim; Lewén, Anders; Hillered, Lars; Enblad, Per

2017-01-01

Background Hyperthermia is a common secondary insult in traumatic brain injury (TBI). The aim was to evaluate the relationship between hyperthermia and intracranial pressure (ICP), and if intracranial compliance and cerebral blood flow (CBF) pressure autoregulation affected that relationship. The relationships between hyperthermia and cerebral oximetry (BtipO2) and cerebral metabolism were also studied. Methods A computerized multimodality monitoring system was used for data collection at the neurointensive care unit. Demographic and monitoring data (temperature, ICP, blood pressure, microdialysis, BtipO2) were analyzed from 87 consecutive TBI patients. ICP amplitude was used as measure of compliance, and CBF pressure autoregulation status was calculated using collected blood pressure and ICP values. Mixed models and comparison between groups were used. Results The influence of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) was small, but individual differences were seen. Linear mixed models showed that hyperthermia raises ICP slightly more when temperature increases in the groups with low compliance and impaired CBF pressure autoregulation. There was also a tendency (not statistically significant) for increased BtipO2, and for increased pyruvate and lactate, with higher temperature, while the lactate/pyruvate ratio and glucose were stable. Conclusions The major finding was that the effects of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) were not extensive in general, but there were exceptional cases. Hyperthermia treatment has many side effects, so it is desirable to identify cases in which hyperthermia is dangerous. Information from multimodality monitoring may be used to guide treatment in individual patients. PMID:28463046

Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and arginine decarboxylase levels

PubMed Central

Zhu, Meng-Yang; Wang, Wei-Ping; Huang, Jingjing; Feng, Yang-Zheng; Regunathan, Soundar; Bissette, Garth

2008-01-01

Agmatine, an endogenous amine derived from decarboxylation of L-arginine catalyzed by arginine decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and arginine decarboxylase expression in rat brains. Sprague-Dawley rats were subjected to two hour immobilization stress daily for seven days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with β-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50 mg/kg/day, i.p.). Likewise, endogenous agmatine levels measured by high performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92% to 265% of controls, were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. These results demonstrate that administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and arginine decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism. PMID:18832001

High temporal resolution delayed analysis of clinical microdialysate streams† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7an01209h

PubMed Central

Gowers, S. A. N.; Hamaoui, K.; Cunnea, P.; Anastasova, S.; Curto, V. F.; Vadgama, P.; Yang, G.-Z.; Papalois, V.; Drakakis, E. M.; Fotopoulou, C.; Weber, S. G.

2018-01-01

This paper presents the use of tubing to store clinical microdialysis samples for delayed analysis with high temporal resolution, offering an alternative to traditional discrete offline microdialysis sampling. Samples stored in this way were found to be stable for up to 72 days at –80 °C. Examples of how this methodology can be applied to glucose and lactate measurement in a wide range of in vivo monitoring experiments are presented. This paper presents a general model, which allows for an informed choice of tubing parameters for a given storage time and flow rate avoiding high back pressure, which would otherwise cause the microdialysis probe to leak, while maximising temporal resolution. PMID:29336454

Monitoring Molecules in Neuroscience Then and Now

PubMed Central

Rice, Margaret E.

2017-01-01

The 16th International Conference on Monitoring Molecules in Neuroscience (MMiN) was held in Gothenburg, Sweden in late spring 2016. This conference originated as a methods meeting focused on in vivo voltammetric techniques and microdialysis. Over time, however, the scope has evolved to include a number of other methods for neurochemical detection that range from single-cell fluorescence in vitro and in vivo in animal models to whole-brain imaging in humans. Overall, MMiN provides a unique forum for introducing new developments in neurochemical detection, as well as for reporting exciting neurobiological insights provided by established and novel methods. This Viewpoint includes a brief history of the meeting, factors that have contributed its evolution, and some highlights of MMiN 2016. PMID:28169519

Monitoring Molecules in Neuroscience Then and Now.

PubMed

Rice, Margaret E

2017-02-15

The 16th International Conference on Monitoring Molecules in Neuroscience (MMiN) was held in Gothenburg, Sweden in late spring 2016. This conference originated as a methods meeting focused on in vivo voltammetric techniques and microdialysis. Over time, however, the scope has evolved to include a number of other methods for neurochemical detection that range from single-cell fluorescence in vitro and in vivo in animal models to whole-brain imaging in humans. Overall, MMiN provides a unique forum for introducing new developments in neurochemical detection, as well as for reporting exciting neurobiological insights provided by established and novel methods. This Viewpoint includes a brief history of the meeting, factors that have contributed its evolution, and some highlights of MMiN 2016.

The effects of postnatal alcohol exposure and galantamine on the context pre-exposure facilitation effect and acetylcholine efflux using in vivo microdialysis

PubMed Central

Perkins, Amy E.; Fadel, Jim R.; Kelly, Sandra J.

2015-01-01

Fetal alcohol spectrum disorders (FASD) affect 2–5% of children. FASD have been shown to cause damage to multiple brain regions, but damage to the hippocampus specifically may explain deficits in learning and memory that are hallmark symptoms of FASD. The acetylcholine neurotransmitter system is a major input to the hippocampus and is a possible target of developmental alcohol exposure. Alcohol (3.0 g/kg/day) was administered via intragastric intubation to developing male rat pups (postnatal day [PD] 2–10; ethanol-treated [ET]), with controls receiving a sham intubation (IC) or no treatment (NC). In Experiment 1, in vivo microdialysis was used to measure acetylcholine efflux in adolescents (PD 32–35). During microdialysis, the effects of a high K+/Ca2+ aCSF solution (PD 32–33) and an acute galantamine (acetylcholinesterase [AChE] inhibitor) injection (2.0 mg/kg; PD 34–35) on acetylcholine efflux were measured. Alcohol-exposed animals did not differ in acetylcholine efflux at baseline. However, alcohol-exposed animals had a decrease in K+/Ca2+-induced acetylcholine efflux compared to non-treated controls, and an enhanced acetylcholine response to galantamine compared to both control groups. Experiment 2 tested whether chronic administration of galantamine (2.0 mg/kg; PD 11–30) could attenuate alcohol-induced learning deficits in the context pre-exposure facilitation effect (CPFE; PD 30–32). Neither chronic galantamine nor postnatal alcohol exposure influenced performance in the CPFE task. Immunohistochemistry was used to measure expression of choline acetyltransferase (ChAT; medial septum), vesicular acetylcholine transporter (vAChT; ventral CA1), and the alpha7 nicotinic acetylcholine receptor (α7 nAChR; ventral CA1) following microdialysis (Exp. 1) or chronic galantamine and behavioral testing (Exp. 2). Neither alcohol exposure nor behavioral testing significantly altered the density of vAChT or α7 nAChRs in the ventral CA1 region of the hippocampus. The average number of ChAT+ cells was increased in the ET animals that displayed the context-shock association; there were no changes in the IC and NC animals that learned the context-shock association or in any of the animals that were in the control task that entailed no learning. Taken together, these results indicate that the hippocampal acetylcholine system is significantly disrupted under conditions of pharmacological manipulations (e.g., galantamine) in alcohol-exposed animals. Furthermore, ChAT was up-regulated in alcohol-exposed animals that learned to associate the context and shock, which may account for their ability to perform this task. Developmental alcohol exposure may disrupt learning and memory in adolescence via a cholinergic mechanism. PMID:25837482

Role of ATP-binding cassette and solute carrier transporters in erlotinib CNS penetration and intracellular accumulation.

PubMed

Elmeliegy, Mohamed A; Carcaboso, Angel M; Tagen, Michael; Bai, Feng; Stewart, Clinton F

2011-01-01

To study the role of drug transporters in central nervous system (CNS) penetration and cellular accumulation of erlotinib and its metabolite, OSI-420. After oral erlotinib administration to wild-type and ATP-binding cassette (ABC) transporter-knockout mice (Mdr1a/b(-/-), Abcg2(-/-), Mdr1a/b(-/-)Abcg2(-/-), and Abcc4(-/-)), plasma was collected and brain extracellular fluid (ECF) was sampled using intracerebral microdialysis. A pharmacokinetic model was fit to erlotinib and OSI-420 concentration-time data, and brain penetration (P(Brain)) was estimated by the ratio of ECF-to-unbound plasma area under concentration-time curves. Intracellular accumulation of erlotinib was assessed in cells overexpressing human ABC transporters or SLC22A solute carriers. P(Brain) in wild-type mice was 0.27 ± 0.11 and 0.07 ± 0.02 (mean ± SD) for erlotinib and OSI-420, respectively. Erlotinib and OSI-420 P(Brain) in Abcg2(-/-) and Mdr1a/b(-/-)Abcg2(-/-) mice were significantly higher than in wild-type mice. Mdr1a/b(-/-) mice showed similar brain ECF penetration as wild-type mice (0.49 ± 0.37 and 0.04 ± 0.02 for erlotinib and OSI-420, respectively). In vitro, erlotinib and OSI-420 accumulation was significantly lower in cells overexpressing breast cancer resistance protein (BCRP) than in control cells. Only OSI-420, not erlotinib, showed lower accumulation in cells overexpressing P-glycoprotein (P-gp) than in control cells. The P-gp/BCRP inhibitor elacridar increased erlotinib and OSI-420 accumulation in BCRP-overexpressing cells. Erlotinib uptake was higher in OAT3- and OCT2-transfected cells than in empty vector control cells. Abcg2 is the main efflux transporter preventing erlotinib and OSI-420 penetration in mouse brain. Erlotinib and OSI-420 are substrates for SLC22A family members OAT3 and OCT2. Our findings provide a mechanistic basis for erlotinib CNS penetration, cellular uptake, and efflux mechanisms. ©2010 AACR.

Microdialysis Sampling Techniques Applied to Studies of the Foreign Body Reaction

PubMed Central

Sides, Cynthia R.; Stenken, Julie A.

2014-01-01

Implanted materials including drug delivery devices and chemical sensors undergo what is termed the foreign body reaction (FBR). Depending on the device and its intended application, the FBR can have differing consequences. An extensive scientific research effort has been devoted to elucidating the cellular and molecular mechanisms that drive the FBR. Important, yet relatively unexplored, research includes the localized tissue biochemistry and the chemical signaling events that occur throughout the FBR. This review provides an overview of the mechanisms of the FBR, describes how the FBR affects different implanted devices, and illustrates the role that microdialysis sampling can play in further elucidating the chemical communication processes that drive FBR outcomes. PMID:24269987

Characterization of beta-phenylethylamine-induced monoamine release in rat nucleus accumbens: a microdialysis study.

PubMed

Nakamura, M; Ishii, A; Nakahara, D

1998-05-22

In vivo microdialysis was used to investigate the effect of beta-phenylethylamine on extracellular levels of monoamines and their metabolites in the nucleus accumbens of conscious rats. At all doses tested (1, 10 and 100 microM), infusion of beta-phenylethylamine through the microdialysis probe significantly increased extracellular levels of dopamine in the nucleus accumbens. These increases were dose-related. The increase in dopamine levels induced by 100 microM beta-phenylethylamine was not affected by co-perfusion of 4 microM tetrodotoxin. The ability of 100 microM beta-phenylethylamine to increase the extracellular level of dopamine was comparable to that of the same dose of methamphetamine. On the other hand, beta-phenylethylamine had a much less potent enhancing effect on 5-hydroxytryptamine (5-HT) than dopamine levels. Only the highest dose (100 microM) caused a statistically significant effect on 5-HT levels. Over the dose range tested (1, 10 and 100 microM), beta-phenylethylamine had no effect on extracellular metabolite levels of dopamine and 5-HT. The results suggest that beta-phenylethylamine increases the efflux of monoamines, preferentially dopamine, without affecting monoamine metabolism, in the nucleus accumbens.

Optical coherence tomography: imaging architect for dermal microdialysis in psoriasis

NASA Astrophysics Data System (ADS)

O'Connell, M.-L.; O'Connor, W.; Ramsay, B.; Guihen, E.; Ho, W. L.; Leahy, M. J.

2011-03-01

Optical coherence tomography (OCT) has been used as part of a ground breaking translational study to shed some light on one of the worlds most prevalent autoimmune diseases; psoriasis. The work successfully integrates the fields of optical imaging, biochemistry and dermatology in conducting a dermal microdialysis (DMD) trial for quantitative histamine assessment amongst a group of psoriasis sufferers. The DMD process involves temporary insertion of microscopic hollow tubes into a layer of skin to measure the levels of histamine and other important biological molecules in psoriasis. For comparison purposes, DMD catheters were implanted into healthy, peri-lesional and lesional skin regions. The catheters' entry and exit points and their precise locations in the epidermal layer of the skin were confirmed using OCT thus obtaining high resolution, wide-field images of the affected skin as well as catheter placement whilst local microdialysis enabled a tissue chemistry profile to be obtained from these three skin regions including histamine, a local immune system activator known to contribute towards itch and inflammation. Together these tools offer a synergistic approach in the clinical assessment of the disease. In addition, OCT delivered a non-invasive and rapid method for analyzing the affected skin architecture.

Effects on sleep and dopamine levels of microdialysis perfusion of cannabidiol into the lateral hypothalamus of rats.

PubMed

Murillo-Rodríguez, Eric; Palomero-Rivero, Marcela; Millán-Aldaco, Diana; Mechoulam, Raphael; Drucker-Colín, René

2011-03-14

The major non-psychoactive component of Cannabis sativa, cannabidiol (CBD), displays a plethora of actions including wakefulness. In the present study, we addressed whether perfusing CBD via microdialysis into lateral hypothalamus (LH) during the lights-on period would modify the sleep-wake cycle of rats as well as the contents of dopamine (DA) collected from nucleus accumbens (AcbC). Additionally, we tested whether perfusion of CBD into LH would block the sleep rebound after a sleep deprivation period. Electroencephalogram and electromyogram electrodes were implanted in rats as well as a guide-cannula aimed to LH or AcbC. CBD perfusion was carried out via cannulae placed into LH whereas contents of DA were collected from AcbC and analyzed using HPLC means. We found that microdialysis perfusion of CBD (30, 60, or 90 nM) into LH of rat enhances alertness and suppresses sleep. This effect was accompanied with an increase in DA extracellular levels collected from the AcbC. Furthermore, perfusion of CBD into LH after total sleep deprivation prevented the sleep rebound. These findings enhance the investigation about the neurobiological properties of CBD on sleep modulation. Copyright © 2011 Elsevier Inc. All rights reserved.

Brain Tissue Responses to Neural Implants Impact Signal Sensitivity and Intervention Strategies

PubMed Central

2015-01-01

Implantable biosensors are valuable scientific tools for basic neuroscience research and clinical applications. Neurotechnologies provide direct readouts of neurological signal and neurochemical processes. These tools are generally most valuable when performance capacities extend over months and years to facilitate the study of memory, plasticity, and behavior or to monitor patients’ conditions. These needs have generated a variety of device designs from microelectrodes for fast scan cyclic voltammetry (FSCV) and electrophysiology to microdialysis probes for sampling and detecting various neurochemicals. Regardless of the technology used, the breaching of the blood–brain barrier (BBB) to insert devices triggers a cascade of biochemical pathways resulting in complex molecular and cellular responses to implanted devices. Molecular and cellular changes in the microenvironment surrounding an implant include the introduction of mechanical strain, activation of glial cells, loss of perfusion, secondary metabolic injury, and neuronal degeneration. Changes to the tissue microenvironment surrounding the device can dramatically impact electrochemical and electrophysiological signal sensitivity and stability over time. This review summarizes the magnitude, variability, and time course of the dynamic molecular and cellular level neural tissue responses induced by state-of-the-art implantable devices. Studies show that insertion injuries and foreign body response can impact signal quality across all implanted central nervous system (CNS) sensors to varying degrees over both acute (seconds to minutes) and chronic periods (weeks to months). Understanding the underlying biological processes behind the brain tissue response to the devices at the cellular and molecular level leads to a variety of intervention strategies for improving signal sensitivity and longevity. PMID:25546652

Nitric oxide synthase inhibition with the antipterin VAS203 improves outcome in moderate and severe traumatic brain injury: a placebo-controlled randomized Phase IIa trial (NOSTRA).

PubMed

Stover, John F; Belli, Antonio; Boret, Henry; Bulters, Diederik; Sahuquillo, Juan; Schmutzhard, Erich; Zavala, Elisabeth; Ungerstedt, Urban; Schinzel, Reinhard; Tegtmeier, Frank

2014-10-01

Traumatic brain injury (TBI) is an important cause of death and disability. Safety and pharmacodynamics of 4-amino-tetrahydrobiopterin (VAS203), a nitric oxide (NO)-synthase inhibitor, were assessed in TBI in an exploratory Phase IIa study (NOSynthase Inhibition in TRAumatic brain injury=NOSTRA). The study included 32 patients with TBI in six European centers. In a first open Cohort, eight patients received three 12-h intravenous infusions of VAS203 followed by a 12-h infusion-free interval over 3 days (total dose 15 mg/kg). Patients in Cohorts 2 and 3 (24) were randomized 2:1 to receive either VAS203 or placebo as an infusion for 48 or 72 h, respectively (total dose 20 and 30 mg/kg). Effects of VAS203 on intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain metabolism using microdialysis, and the therapy intensity level (TIL) were end points. In addition, exploratory analysis of the extended Glasgow Outcome Score (eGOS) after 6 months was performed. Metabolites of VAS203 were detected in cerebral microdialysates. No significant differences between treatment and placebo groups were observed for ICP, CPP, and brain metabolism. TIL on day 6 was significantly decreased (p<0.04) in the VAS203 treated patients. The eGOS after 6 months was significantly higher in treated patients compared with placebo (p<0.01). VAS203 was not associated with hepatic, hematologic, or cardiac toxic effects. At the highest dose administered, four of eight patients receiving VAS203 showed transitory acute kidney injury (stage 2-3). In conclusion, the significant improvement in clinical outcome indicates VAS203-mediated neuroprotection after TBI. At the highest dose, VAS203 is associated with a risk of acute kidney injury.

Brain oxytocin in social fear conditioning and its extinction: involvement of the lateral septum.

PubMed

Zoicas, Iulia; Slattery, David A; Neumann, Inga D

2014-12-01

Central oxytocin (OXT) has anxiolytic and pro-social properties both in humans and rodents, and has been proposed as a therapeutic option for anxiety and social dysfunctions. Here, we utilized a mouse model of social fear conditioning (SFC) to study the effects of OXT on social fear, and to determine whether SFC causes alterations in central OXT receptor (OXTR) binding and local OXT release. Central infusion of OXT, but not arginine vasopressin, prior to social fear extinction training completely abolished social fear expression in an OXTR-mediated fashion without affecting general anxiety or locomotion. SFC caused increased OXTR binding in the dorso-lateral septum (DLS), central amygdala, dentate gyrus, and cornu ammunis 1, which normalized after social fear extinction, suggesting that these areas form part of a brain network involved in the development and neural support of social fear. Microdialysis revealed that the increase in OXT release observed in unconditioned mice within the DLS during social fear extinction training was attenuated in conditioned mice. Consequently, increasing the availability of local OXT by infusion of OXT into the DLS reversed social fear. Thus, alterations in the brain OXT system, including altered OXTR binding and OXT release within the DLS, play an important role in SFC and social fear extinction. Thus, we suggest that the OXT system is adversely affected in disorders associated with social fear, such as social anxiety disorder and reinstalling an appropriate balance of the OXT system may alleviate some of the symptoms.

Zinc release in the lateral nucleus of the amygdala by stimulation of the entorhinal cortex.

PubMed

Takeda, Atsushi; Imano, Sachie; Itoh, Hiromasa; Oku, Naoto

2006-11-06

Zinc release in the lateral nucleus of the amygdala was examined using rat brain slices. The lateral and basolateral nuclei in the amygdala were evidently stained by Timm's sulfide-silver staining method. When the amygdala including both the nuclei was stimulated with 100 mM KCl by means of in vivo microdialysis, extracellular zinc concentration was increased significantly. Zinc release in the lateral nucleus of the amygdala innervated by the entorhinal cortex was next examined in brain slices double-stained with zinc and calcium indicators. Extracellular zinc signal (ZnAF-2) in the lateral nucleus was increased with intracellular calcium signal (calcium orange) during delivery of tetanic stimuli to the entorhinal cortex. Both the increases were completely inhibited by addition of 1 micro M tetrodotoxin, a sodium channel blocker. Furthermore, calcium signal in the lateral nucleus during delivery of tetanic stimuli to the entorhinal cortex was increased in the presence of 10 micro M CNQX, an AMPA/KA receptor antagonist, and this increase was facilitated by addition of 1 mM CaEDTA, a membrane-impermeable zinc chelator. The present study suggested that zinc is released in the lateral nucleus of the amygdala by depolarization of the entorhinal neurons. In the lateral nucleus, zinc released may suppress the increase in presynaptic calcium signal.

Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity

PubMed Central

Sacchi, Silvia; Novellis, Vito De; Paolone, Giovanna; Nuzzo, Tommaso; Iannotta, Monica; Belardo, Carmela; Squillace, Marta; Bolognesi, Paolo; Rosini, Elena; Motta, Zoraide; Frassineti, Martina; Bertolino, Alessandro; Pollegioni, Loredano; Morari, Michele; Maione, Sabatino; Errico, Francesco; Usiello, Alessandro

2017-01-01

D-aspartate levels in the brain are regulated by the catabolic enzyme D-aspartate oxidase (DDO). D-aspartate activates NMDA receptors, and influences brain connectivity and behaviors relevant to schizophrenia in animal models. In addition, recent evidence reported a significant reduction of D-aspartate levels in the post-mortem brain of schizophrenia-affected patients, associated to higher DDO activity. In the present work, microdialysis experiments in freely moving mice revealed that exogenously administered D-aspartate efficiently cross the blood brain barrier and stimulates L-glutamate efflux in the prefrontal cortex (PFC). Consistently, D-aspartate was able to evoke L-glutamate release in a preparation of cortical synaptosomes through presynaptic stimulation of NMDA, mGlu5 and AMPA/kainate receptors. In support of a potential therapeutic relevance of D-aspartate metabolism in schizophrenia, in vitro enzymatic assays revealed that the second-generation antipsychotic olanzapine, differently to clozapine, chlorpromazine, haloperidol, bupropion, fluoxetine and amitriptyline, inhibits the human DDO activity. In line with in vitro evidence, chronic systemic administration of olanzapine induces a significant extracellular release of D-aspartate and L-glutamate in the PFC of freely moving mice, which is suppressed in Ddo knockout animals. These results suggest that the second-generation antipsychotic olanzapine, through the inhibition of DDO activity, increases L-glutamate release in the PFC of treated mice. PMID:28393897

Pharmacological characterization of RS-1259, an orally active dual inhibitor of acetylcholinesterase and serotonin transporter, in rodents: possible treatment of Alzheimer's disease.

PubMed

Abe, Yasuyuki; Aoyagi, Atsushi; Hara, Takao; Abe, Kazumi; Yamazaki, Reina; Kumagae, Yoshihiro; Naruto, Shunji; Koyama, Kazuo; Marumoto, Shinji; Tago, Keiko; Toda, Narihiro; Takami, Kazuko; Yamada, Naho; Ori, Mayuko; Kogen, Hiroshi; Kaneko, Tsugio

2003-09-01

A dual inhibitor of acetylcholinesterase (AChE) and serotonin transporter (SERT), RS-1259 (4-[1S)-methylamino-3-(4-nitrophenoxy)]propylphenyl N,N-dimethylcarbamate (fumaric acid)(1/2)salt), was newly synthesized. RS-1259 simultaneously inhibited AChE and SERT in the brain following an oral administration in mice and rats. Actual simultaneous elevation of extracellular levels of 5-HT and ACh in the rat hippocampus was confirmed by microdialysis. The compound was as effective as SERT inhibitors such as fluoxetine and fluvoxamine in a 5-hydroxytryptophan-enhancing test in mice. Spatial memory deficits in the two-platform task of a water maze in aged rats were ameliorated by RS-1259 as well as donepezil. Both RS-1259 and donepezil increased the awake episodes in the daytime electroencephalogram of rats. Although RS-1259 was weaker than donepezil in enhancing central cholinergic transmission, as observed by ACh elevation in the hippocampus and memory enhancement in aged rats, the efficacy of RS-1259 on the consciousness level, which reflects the whole activity in the brain, was almost the same as that of donepezil. These results suggest that both cholinergic and serotonergic systems are involved in maintaining brain arousal and that a dual inhibitor of AChE and SERT may be useful for the treatment of cognitive disorders associated with reduced brain activity such as in Alzheimer's disease.

Skin glucose metabolism and microvascular blood flow during local insulin delivery and after an oral glucose load.

PubMed

Iredahl, Fredrik; Högstedt, Alexandra; Henricson, Joakim; Sjöberg, Folke; Tesselaar, Erik; Farnebo, Simon

2016-10-01

Insulin causes capillary recruitment in muscle and adipose tissue, but the metabolic and microvascular effects of insulin in the skin have not been studied in detail. The aim of this study was to measure glucose metabolism and microvascular blood flow in the skin during local insulin delivery and after an oral glucose load. Microdialysis catheters were inserted intracutanously in human subjects. In eight subjects two microdialysis catheters were inserted, one perfused with insulin and one with control solution. First the local effects of insulin was studied, followed by a systemic provocation by an oral glucose load. Additionally, as control experiment, six subjects did not recieve local delivery of insulin or the oral glucose load. During microdialysis the local blood flow was measured by urea clearance and by laser speckle contrast imaging (LSCI). Within 15 minutes of local insulin delivery, microvascular blood flow in the skin increased (urea clearance: P=.047, LSCI: P=.002) paralleled by increases in pyruvate (P=.01) and lactate (P=.04), indicating an increase in glucose uptake. An oral glucose load increased urea clearance from the catheters, indicating an increase in skin perfusion, although no perfusion changes were detected with LSCI. The concentration of glucose, pyruvate and lactate increased in the skin after the oral glucose load. Insulin has metabolic and vasodilatory effects in the skin both when given locally and after systemic delivery through an oral glucose load. © 2016 John Wiley & Sons Ltd.

Activation of the mesocortical dopamine system by feeding: lack of a selective response to stress.

PubMed

Taber, M T; Fibiger, H C

1997-03-01

There is wide agreement that catecholamine systems in the prefrontal cortex are activated by stressful stimuli. To date, however, the extent to which other stimuli can increase the activity of these systems has received little attention. In the present study, the effects of tail pinch stress and feeding on dopamine and noradrenaline release in the prefrontal cortex of rats were examined using in vivo brain microdialysis. Both stimuli increased dopamine release, with peak effects reaching 212% above baseline for tail pinch and 165% above baseline for feeding. The effects of the two stimuli on peak dopamine release were not significantly different. Both stimuli also significantly increased noradrenaline release, with peak effects reaching 128% above baseline for tail pinch and 98% above baseline for feeding. The effects of the two stimuli on peak noradrenaline release were not significantly different. These results indicate that activation of catecholaminergic afferents to the prefrontal cortex is not specific to stress, but also occurs in response to non-stressors with positive motivational valence.

Improving amphetamine therapeutic selectivity: N,N-dimethyl-MTA has dopaminergic effects and does not produce aortic contraction.

PubMed

Sotomayor-Zárate, Ramón; Jara, Pablo; Araos, Patricio; Vinet, Raúl; Quiroz, Gabriel; Renard, Georgina M; Espinosa, Pedro; Hurtado-Guzmán, Claudio; Moya, Pablo R; Iturriaga-Vásquez, Patricio; Gysling, Katia; Reyes-Parada, Miguel

2014-05-01

Amphetamine derivatives have therapeutic potential in diseases such as attention deficit hyperactivity disorder, narcolepsy and obesity. However, their prolonged use has been associated with cardiovascular toxicity and addiction. In recent years, we have studied the pharmacological effects of amphetamine derivatives such as methylthioamphetamine (MTA) and N,N-dimethyl-thioamphetamine, with the aim of improving their therapeutic selectivity. In this work, we show that similarly to MTA, N,N-dimethyl-thioamphetamine has effects on the dopamine system, producing a significant increase in extracellular levels of dopamine (as measured by in vivo brain microdialysis) and locomotor activity, which is a behavioural measure of dopaminergic activation. However, unlike MTA, N,N-dimethyl- thioamphetamine does not produce aortic contraction in vitro. Our results show that N,N-dimethyl-thioamphetamine is a drug that retains the dopaminergic effects of amphetamine derivatives but exhibits a lower potential for producing cardiovascular side effects. © 2013 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Application of Light-cured Dental Adhesive Resin for Mounting Electrodes or Microdialysis Probes in Chronic Experiments

PubMed Central

Okumura, Tetsu; Okanoya, Kazuo; Tani, Jun

2007-01-01

In chronic recording experiments, self-curing dental acrylic resins have been used as a mounting base of electrodes or microdialysis-probes. Since these acrylics do not bond to the bone, screws have been used as anchors. However, in small experimental animals like finches or mouse, their craniums are very fragile and can not successfully hold the anchors. In this report, we propose a new application of light-curing dental resins for mounting base of electrodes or microdialysis probes in chronic experiments. This material allows direct bonding to the cranium. Therefore, anchor screws are not required and surgical field can be reduced considerably. Past experiences show that the bonding effect maintains more than 2 months. Conventional resin's window of time when the materials are pliable and workable is a few minutes. However, the window of working time for these dental adhesives is significantly wider and adjustable. PMID:18997897

Multimodality Monitoring for Cerebral Perfusion Pressure Optimization in Comatose Patients with Intracerebral Hemorrhage

PubMed Central

Ko, Sang-Bae; Choi, H. Alex; Parikh, Gunjan; Helbok, Raimund; Schmidt, J. Michael; Lee, Kiwon; Badjatia, Neeraj; Claassen, Jan; Connolly, E. Sander; Mayer, Stephan A.

2011-01-01

Background and Purpose Limited data exists to recommend specific cerebral perfusion pressure (CPP) targets in patients with intracerebral hemorrhage (ICH). We sought to determine the feasibility of brain multimodality monitoring (MMM) for optimizing CPP and potentially reducing secondary brain injury after ICH. Methods We retrospectively analyzed brain MMM data targeted at perihematomal brain tissue in 18 comatose ICH patients (median monitoring: 164 hours). Physiological measures were averaged over one-hour intervals corresponding to each microdialysis sample. Metabolic crisis (MC) was defined as a lactate/pyruvate ratio (LPR) >40 with a brain glucose concentration <0.7 mmol/L. Brain tissue hypoxia (BTH) was defined as PbtO2 <15 mm Hg. Pressure reactivity index (PRx) and oxygen reactivity index (ORx) were calculated. Results Median age was 59 years, median GCS score 6, and median ICH volume was 37.5 ml. The risk of BTH, and to a lesser extent MC, increased with lower CPP values. Multivariable analyses showed that CPP <80 mm Hg was associated with a greater risk of BTH (OR 1.5, 95% CI 1.1–2.1, P=0.01) compared to CPP >100 mm Hg as a reference range. Six patients died (33%). Survivors had significantly higher CPP and PbtO2 and lower ICP values starting on post-bleed day 4, whereas LPR and PRx values were lower, indicating preservation of aerobic metabolism and pressure autoregulation. Conclusions PbtO2 monitoring can be used to identify CPP targets for optimal brain tissue oxygenation. In patients who do not undergo MMM, maintaining CPP >80 mm Hg may reduce the risk of BTH. PMID:21852615

Sex, drugs and gluttony: how the brain controls motivated behaviors.

PubMed

Hull, Elaine M

2011-07-25

Bart Hoebel has forged a view of an integrated neural network that mediates both natural rewards and drug use. He pioneered the use of microdialysis, and also effectively used electrical stimulation, lesions, microinjections, and immunohistochemistry. He found that feeding, stimulant drug administration, and electrical stimulation of the lateral hypothalamus (LH) all increased dopamine (DA) release in the nucleus accumbens (NAc). However, whereas DA in the NAc enhanced motivation, DA in the LH inhibited motivated behaviors. The Hull lab has pursued some of those ideas. We have suggested that serotonin (5-HT) in the perifornical LH inhibits sexual behavior by inhibiting orexin/hypocretin neurons (OX/HCRT), which would otherwise excite neurons in the mesocorticolimbic DA tract. We have shown that DA release in the medial preoptic area (MPOA) is very important for male sexual behavior, and that testosterone, glutamate, nitric oxide (NO) and previous sexual experience promote MPOA DA release and mating. Future research should follow Bart Hoebel's emphasis on neural systems and interactions among brain areas and neurotransmitters. Copyright © 2011 Elsevier Inc. All rights reserved.

Evidence for a role of transporter-mediated currents in the depletion of brain serotonin induced by serotonin transporter substrates.

PubMed

Baumann, Michael H; Bulling, Simon; Benaderet, Tova S; Saha, Kusumika; Ayestas, Mario A; Partilla, John S; Ali, Syed F; Stockner, Thomas; Rothman, Richard B; Sandtner, Walter; Sitte, Harald H

2014-05-01

Serotonin (5-HT) transporter (SERT) substrates like fenfluramine and 3,4-methylenedioxymethamphetamine cause long-term depletion of brain 5-HT, while certain other substrates do not. The 5-HT deficits produced by SERT substrates are dependent upon transporter proteins, but the exact mechanisms responsible are unclear. Here, we compared the pharmacology of several SERT substrates: fenfluramine, d-fenfluramine, 1-(m-chlorophenyl)piperazine (mCPP) and 1-(m-trifluoromethylphenyl)piperainze (TFMPP), to establish relationships between acute drug mechanisms and the propensity for long-term 5-HT depletions. In vivo microdialysis was carried out in rat nucleus accumbens to examine acute 5-HT release and long-term depletion in the same subjects. In vitro assays were performed to measure efflux of [(3)H]5-HT in rat brain synaptosomes and transporter-mediated ionic currents in SERT-expressing Xenopus oocytes. When administered repeatedly to rats (6 mg/kg, i.p., four doses), all drugs produce large sustained elevations in extracellular 5-HT (>5-fold) with minimal effects on dopamine. Importantly, 2 weeks after dosing, only rats exposed to fenfluramine and d-fenfluramine display depletion of brain 5-HT. All test drugs evoke fluoxetine-sensitive efflux of [(3)H]5-HT from synaptosomes, but d-fenfluramine and its bioactive metabolite d-norfenfluramine induce significantly greater SERT-mediated currents than phenylpiperazines. Our data confirm that drug-induced 5-HT release probably does not mediate 5-HT depletion. However, the magnitude of transporter-mediated inward current may be a critical factor in the cascade of events leading to 5-HT deficits. This hypothesis warrants further study, especially given the growing popularity of designer drugs that target SERT.

Evidence for a Role of Transporter-Mediated Currents in the Depletion of Brain Serotonin Induced by Serotonin Transporter Substrates

PubMed Central

Baumann, Michael H; Bulling, Simon; Benaderet, Tova S; Saha, Kusumika; Ayestas, Mario A; Partilla, John S; Ali, Syed F; Stockner, Thomas; Rothman, Richard B; Sandtner, Walter; Sitte, Harald H

2014-01-01

Serotonin (5-HT) transporter (SERT) substrates like fenfluramine and 3,4-methylenedioxymethamphetamine cause long-term depletion of brain 5-HT, while certain other substrates do not. The 5-HT deficits produced by SERT substrates are dependent upon transporter proteins, but the exact mechanisms responsible are unclear. Here, we compared the pharmacology of several SERT substrates: fenfluramine, d-fenfluramine, 1-(m-chlorophenyl)piperazine (mCPP) and 1-(m-trifluoromethylphenyl)piperainze (TFMPP), to establish relationships between acute drug mechanisms and the propensity for long-term 5-HT depletions. In vivo microdialysis was carried out in rat nucleus accumbens to examine acute 5-HT release and long-term depletion in the same subjects. In vitro assays were performed to measure efflux of [3H]5-HT in rat brain synaptosomes and transporter-mediated ionic currents in SERT-expressing Xenopus oocytes. When administered repeatedly to rats (6 mg/kg, i.p., four doses), all drugs produce large sustained elevations in extracellular 5-HT (>5-fold) with minimal effects on dopamine. Importantly, 2 weeks after dosing, only rats exposed to fenfluramine and d-fenfluramine display depletion of brain 5-HT. All test drugs evoke fluoxetine-sensitive efflux of [3H]5-HT from synaptosomes, but d-fenfluramine and its bioactive metabolite d-norfenfluramine induce significantly greater SERT-mediated currents than phenylpiperazines. Our data confirm that drug-induced 5-HT release probably does not mediate 5-HT depletion. However, the magnitude of transporter-mediated inward current may be a critical factor in the cascade of events leading to 5-HT deficits. This hypothesis warrants further study, especially given the growing popularity of designer drugs that target SERT. PMID:24287719

Microdialysis of Soil P: A means to mimic root uptake?

NASA Astrophysics Data System (ADS)

Schack-Kirschner, Helmer; Demand, Dominic; Lang, Friederike

2017-04-01

Standard procedures to assess P availability in soils are based on batch experiments with various extractants. However, in most soils P nutrition is less limited by bulk stocks but by slow diffusion of phosphate through the soil solution. More comparable to the root's approach is to strip phosphate locally from the solid phase by lowering the soil-solution concentration, which can be achieved by establishing an infinite diffusional sink, such as DGT. An alternative diffusive sampling technique is microdialysis (MD), well established in pharmacokinetics. Briefly, this method uses miniaturized flow-through probes where the perfusate gets in diffusive contact to the external solution by a semipermeable membrane. Important aspects of P supply to roots resemble MD sampling. This is not only the mostly diffusive transport, but also an elongated capillary tube-like geometry of absorption. The diameter of typical commercial MD probes is around 500μm. One additional inherent feature of microdialysis is the possibility to release low-molecular substances from the perfusate by diffusion into the matrix, such as carboxylates. However, microdialysis has yet not been used for P in soils. We tested microdialysis in topsoils of an acid beech forest, of an unfertilized grassland and of a fertilized crop site. Three perfusates have been used: 1 mM KNO3, electrolyte + 0.1 mM citric acid, and electrolyte + 1 mM citric acid. We observed rates of uptake into the probes in a range between 1.5*10-15 and 6.7*10-14 mol s-1cm-1 in case of no citrate addition. Surprisingly, these uptake rates were mostly independent of the bulk stocks. Citrate addition increased P yields only in the higher concentration but not in the forest soil. The order of magnitude of MD uptake rates from the soil samples matched root-length related uptake rates from other studies. The micro-radial citrate release in MD reflects the processes controlling phosphate mobilization in the rhizosphere better than measurements based on "flooding" of soil samples with citric acid in batch experiments. Important challenges in MD with phosphate are small volumes of dialysate with extremely low concentrations and a high variability of results due to soil heterogeneity and between-probe variability. We conclude that MD is a promising tool to complement existing P-analytical procedures, especially when spatial aspects or the release of mobilizing substances are in focus.

DERMAL DRUG LEVELS OF ANTIBIOTIC (CEPHALEXIN) DETERMINED BY ELECTROPORATION AND TRANSCUTANEOUS SAMPLING (ETS) TECHNIQUE

PubMed Central

Sammeta, SM; Vaka, SRK; Murthy, S. Narasimha

2009-01-01

The purpose of this project was to assess the validity of a novel “Electroporation and transcutaneous sampling (ETS)” technique for sampling cephalexin from the dermal extracellular fluid (ECF). This work also investigated the plausibility of using cephalexin levels in the dermal ECF as a surrogate for the drug level in the synovial fluid. In vitro and in vivo studies were carried out using hair less rats to assess the workability of ETS. Cephalexin (20mg/kg) was administered i.v. through tail vein and the time course of drug concentration in the plasma was determined. In the same rats, cephalexin concentration in the dermal ECF was determined by ETS and microdialysis techniques. In a separate set of rats, only intraarticular microdialysis was carried out determine the time course of cephalexin concentration in synovial fluid. The drug concentration in the dermal ECF determined by ETS and microdialysis did not differ significantly from each other and so as were the pharmacokinetic parameters. The results provide validity to the ETS technique. Further, there was a good correlation (~0.9) between synovial fluid and dermal ECF levels of cephalexin indicating that dermal ECF levels could be used as a potential surrogate for cephalexin concentration in the synovial fluid. PMID:19067398

Long-term Calibration Considerations during Subcutaneous Microdialysis Sampling in Mobile Rats

PubMed Central

Mou, Xiaodun; Lennartz, Michelle; Loegering, Daniel J.; Stenken, Julie A.

2010-01-01

The level at which implanted sensors and sampling devices maintain their calibration is an important research area. In this work, microdialysis probes with identical geometry and different membranes, polycarbonate/polyether (PC) or polyethersulfone (PES), were used with internal standards (vitamin B12 (MW 1355), antipyrine (MW 188) and 2-deoxyglucose (2-DG, MW 164)) and endogenous glucose to investigate changes in their long-term calibration after implantation into the subcutaneous space of Sprague-Dawley rats. Histological analysis confirmed an inflammatory response to the microdialysis probes and the presence of a collagen capsule. The membrane extraction efficiency (percentage delivered to the tissue space) for antipyrine and 2-DG was not altered throughout the implant lifetime for either PC- or PES-membranes. Yet, Vitamin B12 extraction efficiency and collected glucose concentrations decreased during the implant lifetime. Antipyrine was administered i.v. and its concentrations obtained in both PC-and PES-membrane probes were significantly reduced between the implant day and seven (PC) or 10 (PES) days post implantation suggesting that solute supply is critical for in vivo extraction efficiency. For the low molecular weight solutes such as antipyrine and glucose, localized delivery is not affected by the foreign body reaction, but recovery is significantly reduced. For Vitamin B12, a larger solute, the fibrotic capsule formed around the probe significantly restricts diffusion from the implanted microdialysis probes. PMID:20223515

Sex hormones regulate cerebral drug metabolism via brain miRNAs: down-regulation of brain CYP2D by androgens reduces the analgesic effects of tramadol

PubMed Central

Li, Jie; Xie, Mengmeng; Wang, Xiaoshuang; Ouyang, Xiufang; Wan, Yu; Dong, Guicheng; Yang, Zheqiong; Yang, Jing; Yue, Jiang

2015-01-01

Background and Purpose Brain cytochrome P450 2D (CYP2D) metabolises exogenous neurotoxins, endogenous substances and neurotransmitters. Brain CYP2D can be regulated in an organ-specific manner, but the possible regulatory mechanisms are poorly understood. We investigated the involvement of miRNAs in the selective regulation of brain CYP2D by testosterone and the corresponding alteration of the pharmacological profiles of tramadol by testosterone. Experimental Approach The regulation of CYP2D and brain-enriched miRNAs by testosterone was investigated using SH-SY5Y cells, U251 cells, and HepG2 cells as well as orchiectomized growth hormone receptor knockout (GHR-KO) mice and rats. Concentration–time curves of tramadol in rat brain were determined using a microdialysis technique. The analgesic action of tramadol was assessed by the tail-flick test in rats. Key Results miR-101 and miR-128-2 bound the 3′-untranslated region of the CYP2D6 mRNA and decreased its level. Testosterone decreased CYP2D6 catalytic function via the up-regulation of miR-101 and miR-128-2 in SH-SY5Y and U251 cells, but not in HepG2 cells. Orchiectomy decreased the levels of miR-101 and miR-128-2 in the hippocampus of male GHR-KO mice, indicating that androgens regulate miRNAs directly, not via the alteration of growth hormone secretion patterns. Changes in the pharmacokinetic and pharmacodynamic profiles of tramadol by orchiectomy was attenuated by either testosterone supplementation or a specific brain CYP2D inhibitor. Conclusions and Implications The selective regulation of brain CYP2D via brain-enriched miRNAs, following changes in androgen levels, such as in testosterone therapy, androgen deprivation therapy and/or ageing may alter the response to centrally active substances. PMID:26031356

Locomotor stimulation produced by 3,4-methylenedioxymethamphetamine (MDMA) is correlated with dialysate levels of serotonin and dopamine in rat brain

PubMed Central

Baumann, Michael H.; Clark, Robert D.; Rothman, Richard B.

2008-01-01

(±)-3,4-Methylenedioxymethamphetmine (MDMA, or Ecstasy) is an illicit drug that evokes transporter-mediated release of monoamines, including serotonin (5-HT) and dopamine (DA). Here we monitored the effects of MDMA on neurochemistry and motor activity in rats, as a means to evaluate relationships between 5-HT, DA, and behavior. Male rats undergoing in vivo microdialysis were housed in chambers equipped with photobeams for measurement of ambulation (i.e., forward locomotion) and stereotypy (i.e., head weaving and forepaw treading). Microdialysis probes were placed into the n. accumbens, striatum or prefrontal cortex in separate groups of rats. Dialysate samples were assayed for 5-HT and DA by microbore HPLC-ECD. Rats received two i.v. injections of MDMA, 1 mg/kg followed by 3 mg/kg 60 min later; neurochemical and locomotor parameters were measured concurrently. MDMA produced dose-related elevations in extracellular 5-HT and DA in all regions, with the magnitude of 5-HT release always exceeding that of DA release. MDMA-induced ambulation was positively correlated with dialysate DA levels in all regions (P<0.05-0.0001) and with dialysate 5-HT in striatum and cortex (P<0.001-0.0001). Stereotypy was strongly correlated with dialysate 5-HT in all areas (P<0.001-0.0001) and with dialysate DA in accumbens and striatum (P<0.001-0.0001). These data support previous work and suggest the complex spectrum of behaviors produced by MDMA involves 5-HT and DA in a region- and modality-specific manner. PMID:18403002

PET/CT imaging evidence of FUS-mediated (18)F-FDG uptake changes in rat brain

PubMed Central

Kim, Hyungmin; Park, Mi-Ae; Wang, Shuyan; Chiu, Alan; Fischer, Krisztina; Yoo, Seung-Schik

2013-01-01

Purpose: Transcranial focused ultrasound (FUS) delivers highly focused acoustic energy to a small region of the brain in a noninvasive manner. Recent studies have revealed that FUS, which is administered either in pulsed or continuous waves, can elicit or suppress neural tissue excitability. This neuromodulatory property of FUS has been demonstrated via direct motion detection, electrophysiological recordings, functional magnetic resonance imaging (fMRI), confocal imaging, and microdialysis sampling of neurotransmitters. This study presents new evidence of local increase in glucose metabolism induced by FUS to the rat brain using FDG (18-fludeoxyglucose) positron emission tomography (PET). Methods: Sprague–Dawley rats underwent sonication to a unilateral hemispheric area of the brain prior to PET scan. The pulsed sonication (350 kHz, tone burst duration of 0.5 ms, pulse repetition frequency of 1 kHz, and duration of 300 ms) was applied in 2 s intervals for 40 min immediately after the FDG injection via tail vein. Subsequently, the PET was acquired in dynamic list-mode to image FDG activity for an hour, and reconstructed into a single volume representing standardized uptake value (SUV). The raw SUV as well as its asymmetry index (AI) were measured from five different volume-of-interests (VOIs) of the brain for both hemispheres, and compared between sonicated and unsonicated groups. Results: Statistically significant hemispheric changes in SUV were observed only at the center of sonication focus within the FUS group [paired t-test; t(7) = 3.57, p < 0.05]. There were no significant hemispheric differences in SUV within the control group in any of the VOIs. A statistically significant elevation in AI (t-test; t(7) = 3.40, p < 0.05) was observed at the center of sonication focus (7.9 ± 2.5%, the deviations are in standard error) among the FUS group when compared to the control group (−0.8 ± 1.2%). Conclusions: Spatially distinct increases in the glucose metabolic activity in the rat brain is present only at the center of sonication focus, suggesting localized functional neuromodulation mediated by the sonication. PMID:23464343

On-line preconcentration of fluorescent derivatives of catecholamines in cerebrospinal fluid using flow-gated capillary electrophoresis.

PubMed

Zhang, Qiyang; Gong, Maojun

2016-06-10

Flow-gated capillary electrophoresis (CE) coupled with microdialysis has become an important tool for in vivo bioanalytical measurements because it is capable of performing rapid and efficient separations of complex biological mixtures thus enabling high temporal resolution in chemical monitoring. However, the limit of detection (LOD) is often limited to a micro- or nano-molar range while many important target analytes have picomolar or sub-nanomolar levels in brain and other tissues. To enhance the capability of flow-gated CE for catecholamine detection, a novel and simple on-line sample preconcentration method was developed exclusively for fluorescent derivatives of catecholamines that were fluorogenically derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide. The effective preconcentration coupled with the sensitive laser-induced fluorescence (LIF) detection lowered the LOD down to 20pM for norepinephrine (NE) and 50pM for dopamine (DA) at 3-fold of S/N ratio, and the signal enhancement was estimated to be over 100-fold relative to normal injection when standard analytes were dissolved in artificial cerebrospinal fluid (aCSF). The basic focusing principle is novel since the sample plug contains borate while the background electrolyte (BGE) is void of borate. This strategy took advantage of the complexation between diols and borate, through which one negative charge was added to the complex entity. The sample derivatization mixture was electrokinetically injected into a capillary via the flow-gated injection, and then NE and DA derivatives were selectively focused to a narrow zone by the reversible complexation. Separation of NE and DA derivatives was executed by incoming surfactants of cholate and deoxycholate mixed in the front BGE plug. This on-line preconcentration method was finally applied to the detection of DA in rat cerebrospinal fluid (CSF) via microdialysis and on-line derivatization. It is anticipated that the method would be valuable for in vivo monitoring of DA and NE in various brain regions of live animals on flow-gated CE or microchip platforms. Published by Elsevier B.V.

Effects of beta-phenylethylamine on dopaminergic neurons of the ventral tegmental area in the rat: a combined electrophysiological and microdialysis study.

PubMed

Ishida, Kota; Murata, Mikio; Katagiri, Nobuyuki; Ishikawa, Masago; Abe, Kenji; Kato, Masatoshi; Utsunomiya, Iku; Taguchi, Kyoji

2005-08-01

The effects of systemic administration of beta-phenylethylamine (beta-PEA) and microiontophoretically applied beta-PEA on the spontaneous discharge of dopamine (DA) neurons in the ventral tegmental area (VTA) of the anesthetized rat were examined. Intravenous administration of beta-PEA (1.0, 2.5, and 5.0 mg/kg) and microiontophoretic applications of beta-PEA caused inhibitory responses in DA neurons. Systemic administration and microiontophoretic applications of beta-PEA induced dose- or current-dependent responses. The systemic beta-PEA-induced inhibitory responses were reversed by pretreatment with the DA D(2) receptor antagonists haloperidol (0.5 mg/kg i.p.) and sulpiride (10 mg/kg i.p). Pretreatment with reserpine (5 mg/kg i.p. 24 h earlier) did not completely block the systemic administration of beta-PEA (2.5 mg/kg) inhibition. A microdialysis study of freely moving rats demonstrated that the extracellular DA level increased significantly in response to local application of beta-PEA (100 muM) in the VTA via a microdialysis probe, and local application of beta-PEA-stimulated somatodendritic DA release in the VTA. The beta-PEA-induced release of DA was calcium ion-independent and was enhanced by pretreatment with pertussis toxin. These findings indicate that beta-phenylethylamine inhibits DA neuron activity via DA D(2) autoreceptors in the rat VTA and that this inhibitory effect is mediated by the somatodendritic DA release.

In vivo microdialysis for the evaluation of transfersomes as a novel transdermal delivery vehicle for cinnamic acid.

PubMed

Zhang, Yong-Tai; Xu, Yue-Ming; Zhang, Su-Juan; Zhao, Ji-Hui; Wang, Zhi; Xu, Ding-Qin; Feng, Nian-Ping

2014-03-01

In this study, cinnamic acid-loaded transfersomes were prepared and dermal microdialysis sampling was used in Sprague-Dawley rats to compare the amount of drug released into the skin using transfersomes as transdermal carriers with that released on using conventional liposomes. The formulation of cinnamic acid-loaded transfersomes was optimized by a uniform design through in vitro transdermal permeation studies. Hydration time was confirmed as a significant factor influencing the entrapment efficiency of transfersomes, further affecting their transdermal flux in vitro. The fluxes of cinnamic acid from transfersomes were all higher than those from conventional liposomes, and the flux from the optimal transfersome formulation was 3.01-fold higher than that from the conventional liposomes (p < 0.05). An in vivo microdialysis sampling method revealed that the dermal drug concentrations from transfersomes applied on various skin regions were much lower than those required with conventional liposomes. After the administration of drug-containing transfersomes and liposomes on abdominal skin regions of rats for a period of 10 h, the Cmax of cinnamic acid from the compared liposomes was 3.21 ± 0.25 μg/mL and that from the transfersomes was merely 0.59 ± 0.02 μg/mL. The results suggest that transfersomes can be used as carriers to enhance the transdermal delivery of cinnamic acid, and that these vehicles may penetrate the skin in the complete form, given their significant deformability.

Changes in blood flow and cellular metabolism at a myofascial trigger point with trigger point release (ischemic compression): a proof-of-principle pilot study

PubMed Central

Moraska, Albert F.; Hickner, Robert C.; Kohrt, Wendy M.; Brewer, Alan

2012-01-01

Objective To demonstrate proof-of-principle measurement for physiological change within an active myofascial trigger point (MTrP) undergoing trigger point release (ischemic compression). Design Interstitial fluid was sampled continuously at a trigger point before and after intervention. Setting A biomedical research clinic at a university hospital. Participants Two subjects from a pain clinic presenting with chronic headache pain. Interventions A single microdialysis catheter was inserted into an active MTrP of the upper trapezius to allow for continuous sampling of interstitial fluid before and after application of trigger point therapy by a massage therapist. Main Outcome Measures Procedural success, pain tolerance, feasibility of intervention during sample collection, determination of physiologically relevant values for local blood flow, as well as glucose and lactate concentrations. Results Both patients tolerated the microdialysis probe insertion into the MTrP and treatment intervention without complication. Glucose and lactate concentrations were measured in the physiological range. Following intervention, a sustained increase in lactate was noted for both subjects. Conclusions Identifying physiological constituents of MTrP’s following intervention is an important step toward understanding pathophysiology and resolution of myofascial pain. The present study forwards that aim by showing proof-of-concept for collection of interstitial fluid from an MTrP before and after intervention can be accomplished using microdialysis, thus providing methodological insight toward treatment mechanism and pain resolution. Of the biomarkers measured in this study, lactate may be the most relevant for detection and treatment of abnormalities in the MTrP. PMID:22975226

Brain infection with Staphylococcus aureus leads to high extracellular levels of glutamate, aspartate, γ-aminobutyric acid, and zinc.

PubMed

Hassel, Bjørnar; Dahlberg, Daniel; Mariussen, Espen; Goverud, Ingeborg Løstegaard; Antal, Ellen-Ann; Tønjum, Tone; Maehlen, Jan

2014-12-01

Staphylococcal brain infections may cause mental deterioration and epileptic seizures, suggesting interference with normal neurotransmission in the brain. We injected Staphylococcus aureus into rat striatum and found an initial 76% reduction in the extracellular level of glutamate as detected by microdialysis at 2 hr after staphylococcal infection. At 8 hr after staphylococcal infection, however, the extracellular level of glutamate had increased 12-fold, and at 20 hr it had increased >30-fold. The extracellular level of aspartate and γ-aminobutyric acid (GABA) also increased greatly. Extracellular Zn(2+) , which was estimated at ∼2.6 µmol/liter in the control situation, was increased by 330% 1-2.5 hr after staphylococcal infection and by 100% at 8 and 20 hr. The increase in extracellular glutamate, aspartate, and GABA appeared to reflect the degree of tissue damage. The area of tissue damage greatly exceeded the area of staphylococcal infiltration, pointing to soluble factors being responsible for cell death. However, the N-methyl-D-aspartate receptor antagonist MK-801 ameliorated neither tissue damage nor the increase in extracellular neuroactive amino acids, suggesting the presence of neurotoxic factors other than glutamate and aspartate. In vitro staphylococci incubated with glutamine and glucose formed glutamate, so bacteria could be an additional source of infection-related glutamate. We conclude that the dramatic increase in the extracellular concentration of neuroactive amino acids and zinc could interfere with neurotransmission in the surrounding brain tissue, contributing to mental deterioration and a predisposition to epileptic seizures, which are often seen in brain abscess patients. © 2014 Wiley Periodicals, Inc.

Determination of muscle-specific glucose flux using radioactive stereoisomers and microdialysis

NASA Technical Reports Server (NTRS)

MacLean, D. A.; Ettinger, S. M.; Sinoway, L. I.; Lanoue, K. F.

2001-01-01

The purpose of the present study was to evaluate a novel approach for determining skeletal muscle-specific glucose flux using radioactive stereoisomers and the microdialysis technique. Microdialysis probes were inserted into the vastus lateralis muscle of human subjects and perfused (4 microl/min) with a Ringer solution containing small amounts of radioactive D- and L-glucose as the internal reference markers for determining probe recovery as well as varying concentrations of insulin (0-10 microM). The rationale behind this approach was that both stereoisomers would be equally affected by the factors that determine probe recovery, with the exception of L-glucose, which is nonmetabolizable and would not be influenced by tissue uptake. Therefore, any differences in the probe recovery ratios between the D- and L-stereoisomers represent changes in skeletal muscle glucose uptake directly at the tissue level. There were no differences in probe recovery between the D- (42.3 +/- 3.5%) and L- (41.2 +/- 3.5) stereoisomers during the control period (no insulin), which resulted in a D/L ratio of 1.04 +/- 0.03. However, during insulin perfusion (1 microM), The D/L ratio increased to 1.62 +/- 0.08 and 1.58 +/- 0.07 (P < 0.05) during the two collection (0-15 and 15-30 min) periods, respectively. This was accomplished solely by an increase (P < 0.05) in D-glucose probe recovery, as L-glucose probe recovery remained unchanged. In a second set of experiments, the perfusion of 10 microM insulin did not increase the D/L ratio (1.40 +/- 0.11) above that observed during 1.0 microM (1.41 +/- 0.07) insulin perfusion. These data suggest that this method is sufficiently sensitive to detect differences in insulin-stimulated glucose uptake; thus the use of radioactive stereoisomers in conjunction with the microdialysis technique provides a novel and useful technique for determining tissue-specific glucose flux and insulin sensitivity.

In vivo effects of phosphodiesterase inhibition on basal cyclic guanosine monophosphate levels in the prefrontal cortex, hippocampus and cerebellum of freely moving rats.

PubMed

Marte, Antonella; Pepicelli, Olimpia; Cavallero, Anna; Raiteri, Maurizio; Fedele, Ernesto

2008-11-15

We have characterized the various phosphodiesterases (PDE) that degrade cyclic GMP in the prefrontal cortex, hippocampus, and cerebellum using the microdialysis technique to measure in vivo extracellular cyclic GMP in awake rats. The following PDE blockers were used (100 and 1,000 microM): 8-methoxymethyl-IBMX (8-MM-IBMX), erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), milrinone, rolipram, and zaprinast. For solubility reasons, sildenafil was tested only at 100 microM. All drugs were administered locally in the brain regions through the dialysis probe. At 100 microM, 8-MM-IBMX enhanced the cyclic nucleotide extracellular levels in the prefrontal cortex and hippocampus but not in the cerebellum; EHNA and milrinone were active only in the hippocampus; rolipram was devoid of any effect; zaprinast and sildenafil were effective in all three brain areas. At 1 mM, 8-MM-IBMX, milrinone, and zaprinast increased extracellular cyclic GMP in all the brain regions examined, EHNA became active also in the prefrontal cortex and rolipram showed a significant effect only in the cerebellum. This is the first in vivo functional study showing that, in cortex, PDE1, -2, and -5/9 degrade cGMP, with PDE9 probably playing a major role; in hippocampus, PDE5/9 and PDE1 are mainly involved and seem almost equally active, but PDE2 and -3 also contribute; in cerebellum, PDE5/9 are the main cGMP hydrolyzing enzymes, but also PDE1 and -4 significantly operate.

Effects of acute chlorpyrifos exposure on in vivo acetylcholine accumulation in rat striatum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karanth, Subramanya; Liu, Jing; Mirajkar, Nikita

2006-10-01

This study examined the acute effects of chlorpyrifos (CPF) on cholinesterase inhibition and acetylcholine levels in the striatum of freely moving rats using in vivo microdialysis. Adult, male Sprague-Dawley rats were treated with vehicle (peanut oil, 2 ml/kg) or CPF (84, 156 or 279 mg/kg, sc) and functional signs of toxicity, body weight and motor activity recorded. Microdialysis was conducted at 1, 4 and 7 days after CPF exposure for measurement of acetylcholine levels in striatum. Rats were then sacrificed and the contralateral striatum and diaphragm were collected for biochemical measurements. Few overt signs of cholinergic toxicity were noted inmore » any rats. Body weight gain was significantly affected in the high-dose (279 mg/kg) group only, while motor activity (nocturnal rearing) was significantly reduced in all CPF-treated groups at one day (84 mg/kg) or from 1-4 days (156 and 279 mg/kg) after dosing. Cholinesterase activities in both diaphragm and striatum were markedly inhibited (50-92%) in a time-dependent manner, but there were relatively minimal dose-related changes. In contrast, time- and dose-dependent changes in striatal acetylcholine levels were noted, with significantly higher levels noted in the high-dose group compared to other groups. Maximal increases in striatal acetylcholine levels were observed at 4-7 days after dosing (84 mg/kg, 7-9-fold; 156 mg/kg, 10-13-fold; 279 mg/kg, 35-57-fold). Substantially higher acetylcholine levels were noted when an exogenous cholinesterase inhibitor was included in the perfusion buffer, but CPF treatment-related differences were substantially lower in magnitude under those conditions. The results suggest that marked differences in acetylcholine accumulation can occur with dosages of CPF eliciting relatively similar degrees of cholinesterase inhibition. Furthermore, the minimal expression of classic signs of cholinergic toxicity in the presence of extensive brain acetylcholine accumulation suggests that some compensatory process(es) downstream from synaptic neurotransmitter accumulation limits the expression of toxicity following acute CPF exposure.« less

Relationships among the behavioral, noradrenergic, and pituitary–adrenal responses to interleukin-1 and the effects of indomethacin

PubMed Central

Wieczorek, Marek; Dunn, Adrian J.

2007-01-01

Peripheral administration of interleukin-1 (IL-1) is known to activate the hypothalamo–pituitary–adrenal axis (HPA axis) and brain noradrenergic systems. We studied the relationship between these responses using in vivo microdialysis to assess the release of hypothalamic norepinephrine (NE), while simultaneously sampling blood for ACTH and corticosterone, and monitoring body temperature and behavior in freely moving rats. Rats were implanted with microdialysis probes in the medial hypothalamus, with intravenous catheters, and with telethermometers in the abdomen. Each rat was injected with saline and IL-1β (1 μg ip) in random order, monitoring microdialysate NE, body temperature and plasma ACTH and corticosterone for 2–4 h after injection. Saline injections were followed by transient increases in microdialysate NE and in plasma ACTH and corticosterone. IL-1β injections resulted in prolonged elevations of microdialysate NE, as well as plasma ACTH and corticosterone, and body temperature. IL-1β also induced shivering and a prolonged depression of locomotor activity. Pretreatment with indomethacin (10 mg/kg sc) prevented the IL-1β-induced increases in body temperature and the apparent increase in hypothalamic NE release, but only attenuated the IL-1β-induced shivering and the increase in plasma ACTH. The results indicate a close temporal relationship between the release of NE and HPA axis activation. Such a relationship is also supported by the similar effects of indomethacin pretreatment on NE and ACTH. The shivering is likely involved in the increase in body temperature, but indomethacin only attenuated the shivering while it blocked the fever. However, the effects of indomethacin clearly indicate that neither the increase in body temperature nor the increase in hypothalamic NE release was essential for HPA axis activation. These results suggest that hypothalamic NE is involved in the IL-1-induced HPA axis activation, but that this is not the only mechanism by which the HPA axis is activated by intraperitoneally injected IL-1. PMID:16330180

Relationships among the behavioral, noradrenergic, and pituitary-adrenal responses to interleukin-1 and the effects of indomethacin.

PubMed

Wieczorek, Marek; Dunn, Adrian J

2006-09-01

Peripheral administration of interleukin-1 (IL-1) is known to activate the hypothalamo-pituitary-adrenal axis (HPA axis) and brain noradrenergic systems. We studied the relationship between these responses using in vivo microdialysis to assess the release of hypothalamic norepinephrine (NE), while simultaneously sampling blood for ACTH and corticosterone, and monitoring body temperature and behavior in freely moving rats. Rats were implanted with microdialysis probes in the medial hypothalamus, with intravenous catheters, and with telethermometers in the abdomen. Each rat was injected with saline and IL-1beta (1 microg ip) in random order, monitoring microdialysate NE, body temperature and plasma ACTH and corticosterone for 2-4 h after injection. Saline injections were followed by transient increases in microdialysate NE and in plasma ACTH and corticosterone. IL-1beta injections resulted in prolonged elevations of microdialysate NE, as well as plasma ACTH and corticosterone, and body temperature. IL-1beta also induced shivering and a prolonged depression of locomotor activity. Pretreatment with indomethacin (10 mg/kg sc) prevented the IL-1beta-induced increases in body temperature and the apparent increase in hypothalamic NE release, but only attenuated the IL-1beta-induced shivering and the increase in plasma ACTH. The results indicate a close temporal relationship between the release of NE and HPA axis activation. Such a relationship is also supported by the similar effects of indomethacin pretreatment on NE and ACTH. The shivering is likely involved in the increase in body temperature, but indomethacin only attenuated the shivering while it blocked the fever. However, the effects of indomethacin clearly indicate that neither the increase in body temperature nor the increase in hypothalamic NE release was essential for HPA axis activation. These results suggest that hypothalamic NE is involved in the IL-1-induced HPA axis activation, but that this is not the only mechanism by which the HPA axis is activated by intraperitoneally injected IL-1.

Transferrin receptor antibody-modified α-cobrotoxin-loaded nanoparticles enable drug delivery across the blood-brain barrier by intranasal administration

NASA Astrophysics Data System (ADS)

Liu, Lin; Zhang, Xiangyi; Li, Wuchao; Sun, Haozhen; Lou, Yan; Zhang, Xingguo; Li, Fanzhu

2013-11-01

A novel drug carrier for brain delivery, maleimide-poly(ethyleneglycol)-poly(lactide) (maleimide-PEG-PLA) nanoparticles (NPs) conjugated with mouse-anti-rat monoclonal antibody OX26 (OX26-NPs), was developed and its brain delivery property was evaluated. The diblock copolymers of maleimide-PEG-PLA were synthesized and applied to α-cobrotoxin (αCT)-loaded NPs which were characterized by transmission electron micrograph imaging, Fourier-transform IR, and X-ray diffraction. The NPs encapsulating αCT had a round and vesicle-like shape with a mean diameter around 100 nm, and the OX26 had covalently conjugated to the surface of NPs. MTT studies in brain microvascular endothelial cells (BMEC) revealed a moderate decrease in the cell viability of αCT, when incorporated in OX26-NPs compared to free αCT in solution. A higher affinity of the OX26-αCT-NPs to the BMEC was shown in comparison to αCT-NPs. Then, OX26-αCT-NPs were intranasally (i.n.) administered to rats, and αCT in the periaqueductal gray was monitored for up to 480 min using microdialysis technique in free-moving rats, with i.n. αCT-NPs, i.n. OX26-αCT-NPs, intramuscular injection (i.m.) αCT-NPs, and i.m. OX26-αCT-NPs. The brain transport results showed that the corresponding absolute bioavailability ( F abs) of i.n. OX26-αCT-NPs were about 125 and 155 % with i.n. αCT-NPs and i.m. OX26-αCT-NPs, respectively, and it was found that both the C max and AUC of the four groups were as follows: i.n. OX26-αCT-NPs > i.n. αCT-NPs > i.m. OX26-αCT-NPs > i.m. αCT-NPs, while αCT solution, as control groups, could hardly enter the brain. These results indicated that OX26-NPs are promising carriers for peptide brain delivery.

Effects of systemic carbidopa on dopamine synthesis in rat hypothalamus and striatum

NASA Technical Reports Server (NTRS)

Kaakkola, S.; Tuomainen, P.; Wurtman, R. J.; Maennistoe, P. T.

1991-01-01

Significant concentrations of carbidopa (CD) were found in rat hypothalamus, striatum, and in striatal microdialysis efflux after intraperitoneal administration of the drug. Efflux levels peaked one hour after administration of 100 mg/kg at 0.37 microg/kg or about 2 percent of serum levels. Concurrent CD levels in hypothalamus and striatum were about 2.5 percent and 1.5 percent, respectively, of corresponding serum levels. Levels of dopamine and its principal metabolites in striatal efflux were unaffected. The removal of the brain blood by saline perfusion decreased the striatal and hypothalamic CD concentrations only by 33 percent and 16 percent, respectively. In other rats receiving both CD and levodopa (LD), brain L-dopa, dopamine, and 3,4-dihydroxyphenvlacetic acid (DOPAC) levels after one hour tended to be proportionate to LD dose. When the LD dose remained constant, increasing the CD dose dose-dependently enhanced L-dopa levels in the hypothalamus and striatum. However, dopamine levels did not increase but, in contrast, decreased dose-dependently (although significantly only in the hypothalamus). CD also caused dose-dependent decrease in striatal 3-O-methyldopa (3-OMD) and in striatal and hypothalamic homovanillic acid (HVA), when the LD dose was 50 mg/kg. We conclude that, at doses exceedimg 50 mg/kg, sufficient quantities of CD enter the brain to inhibit dopamine formation, especially in the hypothalamus. Moreover, high doses of LD/CD, both of which are themselves catechols, can inhibit the O-methylation of brain catecholamines formed from the LD.

Effects of systemic carbidopa on dopamine synthesis in rat hypothalamus and striatum

NASA Technical Reports Server (NTRS)

Kaakkola, S.; Tuomainen, P.; Wurtman, R. J.; Mannisto, P. T.

1992-01-01

Significant concentrations of carbidopa (CD) were found in rat hypothalamus, striatum, and in striatal microdialysis efflux after intraperitoneal administration of the drug. Efflux levels peaked one hour after administration of 100 mg/kg at 0.37 micrograms/ml, or about 2% of serum levels. Concurrent CD levels in hypothalamus and striatum were about 2.5% and 1.5%, respectively, of corresponding serum levels. Levels of dopamine and its principal metabolites in striatal efflux were unaffected. The removal of the brain blood by saline perfusion decreased the striatal and hypothalamic CD concentrations only by 33% and 16%, respectively. In other rats receiving both CD and levodopa (LD), brain L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels after one hour tended to be proportionate to LD dose. When the LD dose remained constant, increasing the CD dose dose-dependently enhanced L-dopa levels in the hypothalamus and striatum. However dopamine levels did not increase but, in contrast, decreased dose-dependently (although significantly only in the hypothalamus). CD also caused dose-dependent decrease in striatal 3-O-methyldopa (3-OMD) and in striatal and hypothalamic homovanillic acid (HVA), when the LD dose was 50 mg/kg. We conclude that, at doses exceeding 50 mg/kg, sufficient quantities of CD enter the brain to inhibit dopamine formation, especially in the hypothalamus. Moreover, high doses of LD/CD, both of which are themselves catechols, can inhibit the O-methylation of brain catecholamines formed from the LD.

Neurocircuitry for modeling drug effects.

PubMed

Noori, Hamid R; Spanagel, Rainer; Hansson, Anita C

2012-09-01

The identification and functional understanding of the neurocircuitry that mediates alcohol and drug effects that are relevant for the development of addictive behavior is a fundamental challenge in addiction research. Here we introduce an assumption-free construction of a neurocircuitry that mediates acute and chronic drug effects on neurotransmitter dynamics that is solely based on rodent neuroanatomy. Two types of data were considered for constructing the neurocircuitry: (1) information on the cytoarchitecture and neurochemical connectivity of each brain region of interest obtained from different neuroanatomical techniques; (2) information on the functional relevance of each region of interest with respect to alcohol and drug effects. We used mathematical data mining and hierarchical clustering methods to achieve the highest standards in the preprocessing of these data. Using this approach, a dynamical network of high molecular and spatial resolution containing 19 brain regions and seven neurotransmitter systems was obtained. Further graph theoretical analysis suggests that the neurocircuitry is connected and cannot be separated into further components. Our analysis also reveals the existence of a principal core subcircuit comprised of nine brain regions: the prefrontal cortex, insular cortex, nucleus accumbens, hypothalamus, amygdala, thalamus, substantia nigra, ventral tegmental area and raphe nuclei. Finally, by means of algebraic criteria for synchronizability of the neurocircuitry, the suitability for in silico modeling of acute and chronic drug effects is indicated. Indeed, we introduced as an example a dynamical system for modeling the effects of acute ethanol administration in rats and obtained an increase in dopamine release in the nucleus accumbens-a hallmark of drug reinforcement-to an extent similar to that seen in numerous microdialysis studies. We conclude that the present neurocircuitry provides a structural and dynamical framework for large-scale mathematical models and will help to predict chronic drug effects on brain function. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

Activation of the reticulothalamic cholinergic pathway by the major metabolites of aniracetam.

PubMed

Nakamura, K; Shirane, M

1999-09-10

The aim of the study was to further investigate the effects of aniracetam, a cognition enhancer, and its metabolites on the brain cholinergic system. We measured choline acetyltransferase activity and acetylcholine release using in vivo brain microdialysis in stroke-prone spontaneously hypertensive rats (SHRSP). The enzyme activity in the pons-midbrain and hippocampus, and basal acetylcholine release in the nucleus reticularis thalami were lower in SHRSP than in age-matched Wistar Kyoto rats, indicating central cholinergic deficits in SHRSP. Repeated treatment of aniracetam (50 mg/kg p.o. x 11 for 6 days) preferentially increased the enzyme activity in the thalamus, whereas decreased it in the striatum. Among the metabolites of aniracetam, local perfusion of N-anisoyl-gamma-aminobutyric acid (GABA, 0.1 and/or 1 microM) and p-anisic acid (1 microM) into the nucleus reticularis thalami, dorsal hippocampus and prefrontal cortex of SHRSP produced a significant but delayed increase of acetylcholine release. We failed, however, to find any effect of aniracetam itself. A direct injection of N-anisoyl-GABA (1 nmol) into the pedunculopontine tegmental nucleus of SHRSP enhanced the release in the nucleus reticularis thalami. Thus, these data prove that aniracetam can facilitate central cholinergic neurotransmission via both metabolites. Based on its pharmacokinetic profile, N-anisoyl-GABA may contribute to the clinical effects of aniracetam, mainly by acting on the reticulothalamic cholinergic pathway.

Neuroprotective effects of ebselen following forebrain ischemia: involvement of glutamate and nitric oxide.

PubMed

Koizumi, Hiroyasu; Fujisawa, Hirosuke; Suehiro, Eiichi; Shirao, Satoshi; Suzuki, Michiyasu

2011-01-01

Ebselen is a mimic of glutathione peroxidase that reacts with peroxynitrite and inhibits nitric oxide (NO) synthase. Ebselen has beneficial effects on the neurological outcome of patients with stroke. In this study, the mechanisms by which ebselen can elicit neuroprotective effects against ischemic brain injury were investigated in male Wistar rats. Experimental forebrain ischemia was induced by bilateral common carotid artery occlusion with hemorrhagic hypotension. Ebselen was administered to animals in the treatment group 2 hours prior to the induction of forebrain ischemia, and placebo was administered in the control group. Cerebral blood flow (CBF) was measured by the hydrogen clearance method. Cortical extracellular levels of excitatory amino acids (EAAs) and NO were evaluated using in vivo microdialysis. Neuronal damage in the CA1 subfield of the hippocampus was assessed in brains harvested after a 24-hour period of survival. CBF did not recover to normal physiological levels after ischemic insults in either the control or treatment groups. The differences in the sequential changes in extracellular EAA and NO levels between groups were not statistically significant. There was a significantly larger mean density of intact, undamaged neurons in the CA1 subfield in the treatment group than in the control group. The neuroprotective effects of ebselen were reflected in the histological findings, without significant inhibition of glutamate release or NO synthesis during the acute phase of experimentally induced cerebral ischemia.

In vitro and in vivo physiology of low nanomolar concentrations of Zn2+ in artificial cerebrospinal fluid.

PubMed

Tamano, Haruna; Nishio, Ryusuke; Shakushi, Yukina; Sasaki, Miku; Koike, Yuta; Osawa, Misa; Takeda, Atsushi

2017-02-17

Artificial cerebrospinal fluid (ACSF), i.e., brain extracellular medium, which includes Ca 2+ and Mg 2+ , but not other divalent cations such as Zn 2+ , has been used for in vitro and in vivo experiments. The present study deals with the physiological significance of extracellular Zn 2+ in ACSF. Spontaneous presynaptic activity is suppressed in the stratum lucidum of brain slices from young rats bathed in ACSF containing 10 nM ZnCl 2 , indicating that extracellular Zn 2+ modifies hippocampal presynaptic activity. To examine the in vivo action of 10 nM ZnCl 2 on long-term potentiation (LTP), the recording region was perfused using a recording electrode attached to a microdialysis probe. The magnitude of LTP was not modified in young rats by perfusion with ACSF containing 10 nM ZnCl 2 , compared to perfusion with ACSF without Zn 2+ , but attenuated by perfusion with ACSF containing 100 nM ZnCl 2 . Interestingly, the magnitude of LTP was not modified in aged rats even by perfusion with ACSF containing 100 nM ZnCl 2 , but enhanced by perfusion with ACSF containing 10 mM CaEDTA, an extracellular Zn 2+ chelator. The present study indicates that the basal levels of extracellular Zn 2+ , which are in the range of low nanomolar concentrations, are critical for synaptic activity and perhaps increased age-dependently.

In vitro and in vivo physiology of low nanomolar concentrations of Zn2+ in artificial cerebrospinal fluid

PubMed Central

Tamano, Haruna; Nishio, Ryusuke; Shakushi, Yukina; Sasaki, Miku; koike, Yuta; Osawa, Misa; Takeda, Atsushi

2017-01-01

Artificial cerebrospinal fluid (ACSF), i.e., brain extracellular medium, which includes Ca2+ and Mg2+, but not other divalent cations such as Zn2+, has been used for in vitro and in vivo experiments. The present study deals with the physiological significance of extracellular Zn2+ in ACSF. Spontaneous presynaptic activity is suppressed in the stratum lucidum of brain slices from young rats bathed in ACSF containing 10 nM ZnCl2, indicating that extracellular Zn2+ modifies hippocampal presynaptic activity. To examine the in vivo action of 10 nM ZnCl2 on long-term potentiation (LTP), the recording region was perfused using a recording electrode attached to a microdialysis probe. The magnitude of LTP was not modified in young rats by perfusion with ACSF containing 10 nM ZnCl2, compared to perfusion with ACSF without Zn2+, but attenuated by perfusion with ACSF containing 100 nM ZnCl2. Interestingly, the magnitude of LTP was not modified in aged rats even by perfusion with ACSF containing 100 nM ZnCl2, but enhanced by perfusion with ACSF containing 10 mM CaEDTA, an extracellular Zn2+ chelator. The present study indicates that the basal levels of extracellular Zn2+, which are in the range of low nanomolar concentrations, are critical for synaptic activity and perhaps increased age-dependently. PMID:28211543

Effect of Brain CYP2B Inhibition on Brain Nicotine Levels and Nicotine Self-Administration

PubMed Central

Garcia, Kristine L P; Coen, Kathy; Miksys, Sharon; Lê, Anh Dzung; Tyndale, Rachel F

2015-01-01

The CYP2B enzyme is expressed in human and rat brain, and metabolizes many CNS-acting drugs. The gene that encodes human CYP2B6 is highly polymorphic, where the variation in brain enzyme levels could result in altered brain drug levels. CYP2B can metabolize nicotine, the main psychoactive ingredient in cigarettes; if altered brain CYP2B activity can influence nicotine brain levels, it could influence nicotine-mediated behaviors. To investigate this, a mechanism-based inhibitor selective for CYP2B, C8-xanthate (20 μg), was administered intracerebroventricularly (ICV) into the brain of rats, and 22 h later, nicotine levels were measured by in vivo microdialysis following nicotine (150 μg/kg intravenous). Brain nicotine levels from 15 to 30 min and the AUC0–45min were both twofold higher (p<0.05) with C8-xanthate vs vehicle pretreatment; there was no difference in peripheral nicotine levels. Rats were then given ICV pretreatment with C8-xanthate/ASCF and underwent intravenous nicotine self-administration with 3.75–30 μg/kg per infusion dose. C8-xanthate pretreatment increased responding in progressive ratio (15 μg/kg per infusion dose, p<0.05). In a separate cohort, C8-xanthate increased the percentage of rats that acquired self-administration (7.5 μg/kg per infusion dose, p<0.05) from 40% after vehicle pretreatment to 100%, with no difference in peripheral nicotine levels measured at the end of behavior. In a third cohort, C8-xanthate increased the number of sessions required to meet extinction criteria (p<0.05). Together these data demonstrate that the brain CYP2B activity can influence nicotine brain levels and subsequent behaviors independent of hepatic metabolism. This suggests that human smokers with variable CYP2B brain levels could have different nicotine levels and reinforcement, which might have a role in smoking behaviors and dependence. PMID:25652250

Systemic Injections of Cannabidiol Enhance Acetylcholine Levels from Basal Forebrain in Rats.

PubMed

Murillo-Rodríguez, Eric; Arankowsky-Sandoval, Gloria; Rocha, Nuno Barbosa; Peniche-Amante, Rodrigo; Veras, André Barciela; Machado, Sérgio; Budde, Henning

2018-06-06

Cannabis sativa is a plant that contains more than 500 components, of which the most studied are Δ 9 -tetrahydrocannabinol (Δ 9 -THC) and cannabidiol (CBD). Several studies have indicated that CBD displays neurobiological effects, including wake promotion. Moreover, experimental evidence has shown that injections of CBD enhance wake-related compounds, such as monoamines (dopamine, serotonin, epinephrine, and norepinephrine). However, no clear evidence is available regarding the effects of CBD on additional wake-related neurochemicals such as acetylcholine (ACh). Here, we demonstrate that systemic injections of CBD (0, 5, 10 or 30 mg/kg, i.p.) at the beginning of the lights-on period, increase the extracellular levels of ACh collected from the basal forebrain and measured by microdialysis and HPLC means. Moreover, the time course effects on the contents of ACh were present 5 h post-injection of CBD. Altogether, these data demonstrate that CBD increases ACh levels in a brain region related to wake control. This study is the first to show the effects of ACh levels in CBD-treated rats and suggests that the basal forebrain might be a site of action of CBD for wakefulness modulation.

Episodic Dural Stimulation in Awake Rats: A Model for Recurrent Headache

PubMed Central

Oshinsky, Michael L.; Gomonchareonsiri, Sumittra

2014-01-01

Objectives To model, in rats, the development of chronic trigeminal nociceptive hypersensitivity seen in patients with recurrent headache. Background Pathophysiology studies suggest that patients with recurrent migraine headache experience repeated bouts of dural nociceptor activation. In some patients, the severity and frequency of headache attacks increase over time. Patients with recurrent headache are hypersensitive to nitric oxide donors, such as glyceryl trinitrate (GTN). Current trigeminal pain models do not reflect the repeated episodic nature of dural nociceptor activation in patients with recurrent headache. Repeated nociceptor activation creates long-lasting changes in the periphery and brain due to activity-dependent neuronal plasticity. An animal model of repeated activation of dural nociceptors will facilitate the study of the physiological changes caused by repeated, episodic pain and the factors important for the transition of episodic to chronic migraine. Methods We induced dural inflammation by infusing an inflammatory soup (IS) through a cannula on the dura in awake behaving rats. This was repeated 3 times per week for up to 4 weeks. Periorbital pressure sensory testing was used to monitor the change in trigeminal sensitivity. Rats were challenged with GTN to test the hypothesis that many dural stimulations are required to model the hypersensitivity of migraine patients. Quantitative trigeminal sensory testing and microdialysis in the trigeminal nucleus caudalis (TNC) were used to measure GTN hypersensitivity. Results Multiple infusions of IS (>8), over weeks, induced a long-lasting decrease in periorbital pressure thresholds that lasted >3 weeks after the last infusion. In contrast, IS infusion in IS-naive rats and those that received 3 IS infusions produced only short-lasting decreases in periorbital pressure thresholds. Rats that received more than 8 IS infusions showed a marked increase in their neurochemical and behavioral responses to GTN. In these rats, GTN induced a decrease in periorbital von Frey thresholds that lasted >5 hours. In contrast, in rats that received only 3 IS infusions, GTN caused a threshold decrease for 1.5 hour. In vivo microdialysis in the TNC showed that GTN increased extracellular glutamate levels in rats with more than 8 IS infusions to 7.7 times the basal levels. In IS-naive rats and those that received only 3 IS infusions, the extracellular glutamate levels rose to only 1.7 and 1.9 times the basal level, respectively. Conclusions Repeated IS stimulation of the dura produces a chronic state of trigeminal hypersensitivity and potentiates the response to GTN. This hyperresponsiveness outlasts the last IS infusion and is the basis of our rat model of recurrent headache. This model can be used to study the changes in the brain and periphery induced by repeated trigeminovascular nociceptor activation and has the potential to elucidate the mechanisms for the transition of episodic to chronic headache. PMID:17635594

Bioactive nitric oxide concentration does not increase during reactive hyperemia in human skin.

PubMed

Zhao, J L; Pergola, P E; Roman, L J; Kellogg, D L

2004-02-01

This study examined whether nitric oxide (NO) is involved in the cutaneous response to reactive hyperemia (RH) in the human forearm. We enrolled seven healthy volunteers. NO concentrations were monitored using a NO selective amperometric electrode (ISO-NOP200, World Precision Instruments) inserted into the skin of the forearm. Laser-Doppler flowmetry (Moor Instruments) was used for monitoring skin blood flow (SkBF) at the same site. SkBF and NO levels were monitored and recorded continuously throughout the experiment. An intradermal microdialysis probe was inserted adjacent to the NO electrode for drug delivery. Data collection began 140 min after the NO electrodes and microdialysis probes were inserted. RH was achieved by the inflation of a blood pressure cuff to 25 mmHg above systolic pressure for 7 min after which the pressure in the cuff was abruptly released. Acetylcholine (ACh) was given by microdialysis probe at the end of RH study to verify the ability of the electrode system to detect changes in the NO concentration. SkBF and NO data before RH and immediately, 2, 5, 7, and 10 min after cuff deflation were used for analysis. SkBF increased immediately after release of the occlusion (P < 0.0001) and remained elevated for 2 min. No significant NO changes occurred with the increases in LDF. ACh induced increases in both SkBF and NO (P < 0.000 and P < 0.037, respectively). We conclude that RH increases SkBF by mechanisms that do not require a measurable increase in NO concentrations.

INTERSTITIAL PLASMIN ACTIVITY WITH EPSILON AMINOCAPROIC ACID: TEMPORAL AND REGIONAL HETEROGENEITY

PubMed Central

Reust, Daryl L.; Reeves, Scott T.; Abernathy, James H.; Dixon, Jennifer A.; Gaillard, William F.; Mukherjee, Rupak; Koval, Christine N.; Stroud, Robert E.; Spinale, Francis G.

2010-01-01

Background Epsilon aminocaproic acid (EACA) is used in cardiac surgery to modulate plasmin activity (PLact). The present study developed a fluorogenic-microdialysis system to measure in-vivo region specific temporal changes in PLact following EACA administration. Methods Pigs (25-35kg) received EACA (75mg/kg, n=7) or saline in which microdialysis probes were placed in the liver, myocardium, kidney and quadricep muscle. The microdialysate contained a plasmin specific fluorogenic peptide and fluorescence emission, which directly reflected PLact, determined at baseline, 30, 60, 90 and 120 minutes following EACA/vehicle infusion. Results EACA caused significant decreases in liver and quadricep PLact at 60, 90, 120 minutes and at 30, 60, 120 minutes respectively (p<0.05). In contrast, EACA induced significant biphasic changes in heart and kidney PLact profiles with initial increases followed by decreases at 90 and 120 minutes (p<0.05). The peak EACA interstitial concentrations for all compartments occurred at 30 minutes post infusion, and were 5-fold higher in the renal compartment and 4-fold higher in the myocardium, when compared to the liver or muscle (p<0.05). Conclusions Using a large animal model and in-vivo microdialysis measurements of plasmin activity, the unique findings from this study were 2-fold. First, EACA induced temporally distinct plasmin activity profiles within the plasma and interstitial compartments. Second, EACA caused region specific changes in plasmin activity profiles. These temporal and regional heterogeneic effects of EACA may have important therapeutic considerations when managing fibrinolysis in the perioperative period. PMID:20417774

Interstitial plasmin activity with epsilon aminocaproic acid: temporal and regional heterogeneity.

PubMed

Reust, Daryl L; Reeves, Scott T; Abernathy, James H; Dixon, Jennifer A; Gaillard, William F; Mukherjee, Rupak; Koval, Christine N; Stroud, Robert E; Spinale, Francis G

2010-05-01

Epsilon aminocaproic acid (EACA) is used in cardiac surgery to modulate plasmin activity (PLact). The present study developed a fluorogenic-microdialysis system to measure in vivo region specific temporal changes in PLact after EACA administration. Pigs (25 to 35 kg) received EACA (75 mg/kg, n = 7) or saline in which microdialysis probes were placed in the liver, myocardium, kidney, and quadricep muscle. The microdialysate contained a plasmin-specific fluorogenic peptide and fluorescence emission, which directly reflected PLact, determined at baseline, 30, 60, 90, and 120 minutes after EACA/vehicle infusion. Epsilon aminocaproic acid caused significant decreases in liver and quadricep PLact at 60, 90, 120 minutes, and at 30, 60, and 120 minutes, respectively (p < 0.05). In contrast, EACA induced significant biphasic changes in heart and kidney PLact profiles with initial increases followed by decreases at 90 and 120 minutes (p < 0.05). The peak EACA interstitial concentrations for all compartments occurred at 30 minutes after infusion, and were fivefold higher in the renal compartment and fourfold higher in the myocardium, when compared with the liver or muscle (p < 0.05). Using a large animal model and in vivo microdialysis measurements of plasmin activity, the unique findings from this study were twofold. First, EACA induced temporally distinct plasmin activity profiles within the plasma and interstitial compartments. Second, EACA caused region-specific changes in plasmin activity profiles. These temporal and regional heterogeneic effects of EACA may have important therapeutic considerations when managing fibrinolysis in the perioperative period. Copyright (c) 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Local opiate receptors in the sinoatrial node moderate vagal bradycardia.

PubMed

Farias, M; Jackson, K; Stanfill, A; Caffrey, J L

2001-02-20

Met-enkephalin-arg-phe (MEAP) interrupts vagal bradycardia when infused into the systemic circulation. This study was designed to locate the opiate receptors functionally responsible for this inhibition. Previous observations suggested that the receptors were most likely located in either intracardiac parasympathetic ganglia or the pre-junctional nerve terminals innervating the sinoatrial node. In this study 10 dogs were instrumented with a microdialysis probe inserted into the sinoatrial node. The functional position of the probe was tested by briefly introducing norepinephrine into the probe producing an increase in heart rate of more than 30 beats/min. Vagal stimulations were conducted at 0.5, 1.2 and 4 Hz during vehicle infusion (saline ascorbate). Cardiovascular responses during vagal stimulation were recorded on-line. MEAP was infused directly into the sinoatrial node via the microdialysis probe. The evaluation of vagal bradycardia was repeated during the nodal application of MEAP, diprenorphine (opiate antagonist), and diprenorphine co-infused with MEAP. MEAP introduced into the sinoatrial node via the microdialysis probe reduced vagal bradycardia by more than half. Simultaneous local nodal blockade of these receptors with the opiate antagonist, diprenorphine, eliminated the effect of MEAP demonstrating the participation by opiate receptors. Systemic infusions of MEAP produced a reduction in vagal bradycardia nearly identical to that observed during nodal administration. When local nodal opiate receptors were blocked with diprenorphine, the systemic effect of MEAP was eliminated. These data lead us to suggest that the opiate receptors responsible for the inhibition of vagal bradycardia are located within the sinoatrial node with few, if any, participating extra-nodal or ganglionic receptors.

Current Opportunities for Clinical Monitoring of Axonal Pathology in Traumatic Brain Injury

PubMed Central

Tsitsopoulos, Parmenion P.; Abu Hamdeh, Sami; Marklund, Niklas

2017-01-01

Traumatic brain injury (TBI) is a multidimensional and highly complex disease commonly resulting in widespread injury to axons, due to rapid inertial acceleration/deceleration forces transmitted to the brain during impact. Axonal injury leads to brain network dysfunction, significantly contributing to cognitive and functional impairments frequently observed in TBI survivors. Diffuse axonal injury (DAI) is a clinical entity suggested by impaired level of consciousness and coma on clinical examination and characterized by widespread injury to the hemispheric white matter tracts, the corpus callosum and the brain stem. The clinical course of DAI is commonly unpredictable and it remains a challenging entity with limited therapeutic options, to date. Although axonal integrity may be disrupted at impact, the majority of axonal pathology evolves over time, resulting from delayed activation of complex intracellular biochemical cascades. Activation of these secondary biochemical pathways may lead to axonal transection, named secondary axotomy, and be responsible for the clinical decline of DAI patients. Advances in the neurocritical care of TBI patients have been achieved by refinements in multimodality monitoring for prevention and early detection of secondary injury factors, which can be applied also to DAI. There is an emerging role for biomarkers in blood, cerebrospinal fluid, and interstitial fluid using microdialysis in the evaluation of axonal injury in TBI. These biomarker studies have assessed various axonal and neuroglial markers as well as inflammatory mediators, such as cytokines and chemokines. Moreover, modern neuroimaging can detect subtle or overt DAI/white matter changes in diffuse TBI patients across all injury severities using magnetic resonance spectroscopy, diffusion tensor imaging, and positron emission tomography. Importantly, serial neuroimaging studies provide evidence for evolving axonal injury. Since axonal injury may be a key risk factor for neurodegeneration and dementias at long-term following TBI, the secondary injury processes may require prolonged monitoring. The aim of the present review is to summarize the clinical short- and long-term monitoring possibilities of axonal injury in TBI. Increased knowledge of the underlying pathophysiology achieved by advanced clinical monitoring raises hope for the development of novel treatment strategies for axonal injury in TBI. PMID:29209266

Characterization of noradrenaline release in the locus coeruleus of freely moving awake rats by in vivo microdialysis.

PubMed

Fernández-Pastor, Begoña; Mateo, Yolanda; Gómez-Urquijo, Sonia; Javier Meana, J

2005-07-01

The origin and regulation of noradrenaline (NA) in the locus coeruleus (LC) is unknown. The neurochemical features of NA overflow (nerve impulse dependence, neurotransmitter synthesis, vesicle storage, reuptake, alpha2-adrenoceptor-mediated regulation) were characterized in the LC. Brain microdialysis was performed in awake rats. Dialysates were analyzed for NA. NA in the LC decreased via local infusion of Ca2+-free medium (-42+/-5%) or the sodium channel blocker tetrodotoxine (TTX) (-47+/-8%) but increased (333+/-40%) via KCl-induced depolarization. The tyrosine hydroxylase (TH) inhibitor alpha-methyl-p-tyrosine (250 mg kg(-1), i.p.) and the vesicle depletory drug reserpine (5 mg kg(-1), i.p.) decreased NA. Therefore, extracellular NA in the LC satisfies the criteria for an impulse flow-dependent vesicular exocytosis of neuronal origin. Local perfusion of the alpha2-adrenoceptor agonist clonidine (0.1-100 microM) decreased NA (E(max)=-79+/-5%) in the LC, whereas the opposite effect (E(max)=268+/-53%) was observed with the alpha2A-adrenoceptor antagonist BRL44408 (0.1-100 microM). This suggests a tonic modulation of NA release through local alpha2A-adrenoceptors. The selective NA reuptake inhibitor desipramine (DMI) (0.1-100 microM) administered into the LC increased NA in the LC (E(max)=223+/-40%) and simultaneously decreased NA in the cingulate cortex, confirming the modulation exerted by NA in the LC on firing activity of noradrenergic cells and on the subsequent NA release in noradrenergic terminals. Synaptic processes underlying NA release in the LC are similar to those in noradrenergic terminal areas. NA in the LC could represent local somatodendritic release, but also the presence of neurotransmitter release from collateral axon terminals.

Differential Acetylcholine Release in the Prefrontal Cortex and Hippocampus During Pavlovian Trace and Delay Conditioning

PubMed Central

Flesher, M. Melissa; Butt, Allen E.; Kinney-Hurd, Brandee L.

2011-01-01

Pavlovian trace conditioning critically depends on the medial prefrontal cortex (mPFC) and hippocampus (HPC), whereas delay conditioning does not depend on these brain structures. Given that the cholinergic basal forebrain system modulates activity in both the mPFC and HPC, it was reasoned that the level of acetylcholine (ACh) release in these regions would show distinct profiles during testing in trace and delay conditioning paradigms. To test this assumption, microdialysis probes were implanted unilaterally into the mPFC and HPC of rats that were pre-trained in appetitive trace and delay conditioning paradigms using different conditional stimuli in the two tasks. On the day of microdialysis testing, dialysate samples were collected during a quiet baseline interval before trials were initiated, and again during performance in separate blocks of trace and delay conditioning trials in each animal. ACh levels were quantified using high performance liquid chromatography and electrochemical detection techniques. Consistent with our hypothesis, results showed that ACh release in the mPFC was greater during trace conditioning than during delay conditioning. The level of ACh released during trace conditioning in the HPC was also greater than the levels observed during delay conditioning. While ACh efflux in both the mPFC and HPC selectively increased during trace conditioning, ACh levels in the mPFC during trace conditioning testing showed the greatest increases observed. These results demonstrate a dissociation in cholinergic activation of the mPFC and HPC during performance in trace but not delay appetitive conditioning, where this cholinergic activity may contribute to attentional mechanisms, adaptive response timing, or memory consolidation necessary for successful trace conditioning. PMID:21514394

Three-dimensional printed sample load/inject valves enabling online monitoring of extracellular calcium and zinc ions in living rat brains.

PubMed

Su, Cheng-Kuan; Hsia, Sheng-Chieh; Sun, Yuh-Chang

2014-08-01

We have developed a simple and low-cost flow injection system coupled to a quadruple ICP-MS for the direct and continuous determination of multi-element in microdialysates. To interface microdialysis sampling to an inductively coupled plasma mass spectrometer (ICP-MS), we employed 3D printing to manufacture an as-designed sample load/inject valve featuring an in-valve sample loop for precise handling of microliter samples with a dissolved solids content of 0.9% NaCl (w/v). To demonstrate the practicality of our developed on-line system, we applied the 3D printed valve equipped a 5-μL sample loop to minimize the occurrence of salt matrix effects and facilitate an online dynamic monitoring of extracellular calcium and zinc ions in living rat brains. Under the practical condition (temporal resolution: 10h(-1)), dynamic profiling of these two metal ions in living rat brain extracellular fluid after probe implantation (the basal values for Ca and Zn were 12.11±0.10mg L(-1) and 1.87±0.05μg L(-1), respectively) and real-time monitoring of the physiological response to excitotoxic stress elicited upon perfusing a solution of 2.5mM N-methyl-d-aspartate were performed. Copyright © 2014 Elsevier B.V. All rights reserved.

Inhibition of prolyl oligopeptidase by KYP-2047 fails to increase the extracellular neurotensin and substance P levels in rat striatum.

PubMed

Jalkanen, Aaro J; Savolainen, Katja; Forsberg, Markus M

2011-09-15

Prolyl oligopeptidase (PREP, EC 3.4.21.26) hydrolyzes neuropeptides, such as neurotensin and substance P in vitro, but its importance in the in vivo metabolism of these peptides has not been proved. This is the first report where intracerebral microdialysis combined with highly sensitive radioimmunoassay has been used to investigate the effect of PREP inhibition on the brain extracellular peptide levels in conscious rats. We show that PREP inhibition by KYP-2047 (50μmol/kg=17mg/kg, intraperitoneally, that effectively inhibits PREP in the brain), has no effect on the neurotensin and substance P levels in the striatum extracellular space. This provides a further piece of evidence in support of the proposition that PREP is not significantly responsible for the in vivo cleavage of substance P or neurotensin, and that occasional positive cognitive effects associated with some PREP inhibitors are not mediated through elevated extracellular levels of these peptides. Direct regulation of peptide processing by PREP is not likely because the enzyme is located intracellularly and the peptide substrates are mostly extracellular. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Amperometric determination of 6-mercaptopurine on functionalized multi-wall carbon nanotubes modified electrode by liquid chromatography coupled with microdialysis and its application to pharmacokinetics in rabbit.

PubMed

Cao, Xu-Ni; Lin, Li; Zhou, Yu-Yan; Shi, Guo-Yue; Zhang, Wen; Yamamoto, Katsunobu; Jin, Li-Tong

2003-07-27

In this paper, multi-wall carbon nanotubes functionalized with carboxylic groups modified electrode (MWNT-COOH CME) was fabricated. This chemically modified electrode (CME) can be used as the working electrode in the liquid chromatography for the determination of 6-mercaptopurine (6-MP). The results indicate that the CME exhibits efficiently electrocatalytic oxidation for 6-MP with relatively high sensitivity, stability and long-life. The peak currents of 6-MP are linear to its concentrations ranging from 4.0 x 10(-7) to 1.0 x 10(-4) mol l(-1) with the calculated detection limit (S/N=3) of 2.0 x 10(-7) mol l(-1). Coupled with microdialysis, the method has been successfully applied to the pharmacokinetic study of 6-MP in rabbit blood. This method provides a fast, sensible and simple technique for the pharmacokinetic study of 6-MP in vivo.

Serotonergic neurotoxic metabolites of ecstasy identified in rat brain.

PubMed

Jones, Douglas C; Duvauchelle, Christine; Ikegami, Aiko; Olsen, Christopher M; Lau, Serrine S; de la Torre, Rafael; Monks, Terrence J

2005-04-01

The selective serotonergic neurotoxicity of 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) depends on their systemic metabolism. We have recently shown that inhibition of brain endothelial cell gamma-glutamyl transpeptidase (gamma-GT) potentiates the neurotoxicity of both MDMA and MDA, indicating that metabolites that are substrates for this enzyme contribute to the neurotoxicity. Consistent with this view, glutathione (GSH) and N-acetylcysteine conjugates of alpha-methyl dopamine (alpha-MeDA) are selective neurotoxicants. However, neurotoxic metabolites of MDMA or MDA have yet to be identified in brain. Using in vivo microdialysis coupled to liquid chromatography-tandem mass spectroscopy and a high-performance liquid chromatography-coulometric electrode array system, we now show that GSH and N-acetylcysteine conjugates of N-methyl-alpha-MeDA are present in the striatum of rats administered MDMA by subcutaneous injection. Moreover, inhibition of gamma-GT with acivicin increases the concentration of GSH and N-acetylcysteine conjugates of N-methyl-alpha-MeDA in brain dialysate, and there is a direct correlation between the concentrations of metabolites in dialysate and the extent of neurotoxicity, measured by decreases in serotonin (5-HT) and 5-hydroxyindole acetic (5-HIAA) levels. Importantly, the effects of acivicin are independent of MDMA-induced hyperthermia, since acivicin-mediated potentiation of MDMA neurotoxicity occurs in the context of acivicin-mediated decreases in body temperature. Finally, we have synthesized 5-(N-acetylcystein-S-yl)-N-methyl-alpha-MeDA and established that it is a relatively potent serotonergic neurotoxicant. Together, the data support the contention that MDMA-mediated serotonergic neurotoxicity is mediated by the systemic formation of GSH and N-acetylcysteine conjugates of N-methyl-alpha-MeDA (and alpha-MeDA). The mechanisms by which such metabolites access the brain and produce selective serotonergic neurotoxicity remain to be determined.

Short-term dopaminergic regulation of GABA release in dopamine deafferented caudate-putamen is not directly associated with glutamic acid decarboxylase gene expression.

PubMed

O'Connor, W T; Lindefors, N; Brené, S; Herrera-Marschitz, M; Persson, H; Ungerstedt, U

1991-07-08

In vivo microdialysis and in situ hybridization were combined to study dopaminergic regulation of gamma-amino butyric acid (GABA) neurons in rat caudate-putamen (CPu). Potassium-stimulated GABA release in CPu was elevated following a dopamine deafferentation. Local perfusion with exogenous dopamine (50 microM) for 3 h via the microdialysis probe attenuated the potassium-stimulated increase in extracellular GABA in CPu. Expression of glutamic acid decarboxylase (GAD) mRNA was also increased in the dopamine deafferented CPu. However, local perfusion with dopamine had no significant attenuating effect on the increased GAD mRNA expression. These findings indicate that dopaminergic regulation of GABA neurons in the dopamine deafferented CPu includes both a short-term effect at the level of GABA release independent of changes in GAD mRNA expression and a long-term modulation at the level of GAD gene expression.

Tyrosine - Effects on catecholamine release

NASA Technical Reports Server (NTRS)

Acworth, Ian N.; During, Matthew J.; Wurtman, Richard J.

1988-01-01

Tyrosine administration elevates striatal levels of dopamine metabolites in animals given treatments that accelerate nigrostriatal firing, but not in untreated rats. We examined the possibility that the amino acid might actually enhance dopamine release in untreated animals, but that the technique of measuring striatal dopamine metabolism was too insensitive to demonstrate such an effect. Dopamine release was assessed directly, using brain microdialysis of striatal extracellular fluid. Tyrosine administration (50-200 mg/kg IP) did indeed cause a dose related increase in extracellular fluid dopamine levels with minor elevations in levels of DOPAC and HVA, its major metabolites, which were not dose-related. The rise in dopamine was short-lived, suggesting that receptor-mediated feedback mechanisms responded to the increased dopamine release by diminishing neuronal firing or sensitivity to tyrosine. These observations indicate that measurement of changes in striatal DOPAC and HVA, if negative, need not rule out increases in nigrostriatal dopamine release.

Aniracetam enhances glutamatergic transmission in the prefrontal cortex of stroke-prone spontaneously hypertensive rats.

PubMed

Togashi, Hiroko; Nakamura, Kazuo; Matsumoto, Machiko; Ueno, Ken-ichi; Ohashi, Satoshi; Saito, Hideya; Yoshioka, Mitsuhiro

2002-03-08

The effects of aniracetam, a cognition enhancer, on extracellular levels of glutamate (Glu), gamma-aminobutyric acid (GABA) and nitric oxide metabolites (NOx) were examined in the prefrontal cortex (PFC) and the basolateral amygdala (AMG) in stroke-prone spontaneously hypertensive rats (SHRSP) using in vivo microdialysis. Basal release of Glu, was lower in the AMG of SHRSP than in normotensive Wistar Kyoto rats, whereas no difference in GABA and NOx was noted. Aniracetam (100 mg/kg, p.o.) significantly increased the area under the curve of Glu levels in the PFC, but not in the AMG, of SHRSP. Aniracetam failed to exert any remarkable effects on GABA or NOx levels in either brain region. Our findings suggest that aniracetam enhances cortical glutamatergic release, which may be the mechanism involved in the ameliorating effects of aniracetam on various neuronal dysfunctions.

[GABA-NO interaction in the N. Accumbens during danger-induced inhibition of exploratory behavior].

PubMed

Saul'skaia, N V; Terekhova, E A

2013-01-01

In Sprague-Dawley rats by means of in vivo microdialysis combined with HPLC analysis, it was shown that presentation to rats during exploratory activity of a tone previously pared with footshock inhibited the exploration and prevented the exploration-induced increase in extracellular levels of citrulline (an NO co-product) in the medial n. accumbens. Intra-accumbal infusions of 20 μM bicuculline, a GABA(A)-receptor antagonist, firstly, partially restored the exploration-induced increase of extracellular citrulline levels in this brain area, which was inhibited by presentation of the tone, previously paired with foot-shock and, secondly, prevented the inhibition of exploratory behavior produced by this sound signal of danger. The data obtained indicate for the first time that signals of danger inhibit exploratory behavior and exploration-induced activation of the accumbal nitrergic system via GABA(A)-receptor mechanisms.

Cerebral Taurine Levels are Associated with Brain Edema and Delayed Cerebral Infarction in Patients with Aneurysmal Subarachnoid Hemorrhage.

PubMed

Kofler, Mario; Schiefecker, Alois; Ferger, Boris; Beer, Ronny; Sohm, Florian; Broessner, Gregor; Hackl, Werner; Rhomberg, Paul; Lackner, Peter; Pfausler, Bettina; Thomé, Claudius; Schmutzhard, Erich; Helbok, Raimund

2015-12-01

Cerebral edema and delayed cerebral infarction (DCI) are common complications after aneurysmal subarachnoid hemorrhage (aSAH) and associated with poor functional outcome. Experimental data suggest that the amino acid taurine is released into the brain extracellular space secondary to cytotoxic edema and brain tissue hypoxia, and therefore may serve as a biomarker for secondary brain injury after aSAH. On the other hand, neuroprotective mechanisms of taurine treatment have been described in the experimental setting. We analyzed cerebral taurine levels using high-performance liquid chromatography in the brain extracellular fluid of 25 consecutive aSAH patients with multimodal neuromonitoring including cerebral microdialysis (CMD). Patient characteristics and clinical course were prospectively recorded. Associations with CMD-taurine levels were analyzed using generalized estimating equations with an autoregressive process to handle repeated observations within subjects. CMD-taurine levels were highest in the first days after aSAH (11.2 ± 3.2 µM/l) and significantly decreased over time (p < 0.001). Patients with brain edema on admission or during hospitalization (N = 20; 80 %) and patients developing DCI (N = 5; 20 %) had higher brain extracellular taurine levels compared to those without (Wald = 7.3, df = 1, p < 0.01; Wald = 10.1, df = 1, p = 0.001, respectively) even after adjusting for disease severity and CMD-probe location. There was no correlation between parenteral taurine supplementation and brain extracellular taurine (p = 0.6). Moreover, a significant correlation with brain extracellular glutamate (r = 0.82, p < 0.001), lactate (r = 0.56, p < 0.02), pyruvate (r = 0.39, p < 0.01), potassium (r = 0.37, p = 0.01), and lactate-to-pyruvate ratio (r = 0.24, p = 0.02) was found. Significantly higher CMD-taurine levels were found in patients with brain edema or DCI after aneurysmal subarachnoid hemorrhage. Its value as a potential biomarker deserves further investigation.

Ferrum nano particles and multiwall carbon nano tubes based electrode as FIA detector for determination of amino acids in hypothalamus microdialysis fluids

NASA Astrophysics Data System (ADS)

Sun, L.; Wang, J.; Wang, Y. T.; Yu, L.; Peng, H.; Zhu, J. Z.

2017-01-01

An amperometric electrode based on multiwall carbon nanotubes (MWCNTs) and Fe nanoparticles (NPs) has been successfully fabricated. Combined with Flow Injection Analysis (FIA) and chromatography separation column, the electrode exhibits linear response in the concentration range of 0.1 -12 μM and the sensitivity of 30.0 nA μM-1 for most of amino acids. The determination of 17 amino acids in the hypothalamus microdialysis fluids of guinea pigs, illustrates that the electrode is a powerful tool to investigate physiology and pathology mechanisms

Safinamide Differentially Modulates In Vivo Glutamate and GABA Release in the Rat Hippocampus and Basal Ganglia.

PubMed

Morari, Michele; Brugnoli, Alberto; Pisanò, Clarissa Anna; Novello, Salvatore; Caccia, Carla; Melloni, Elsa; Padoani, Gloria; Vailati, Silvia; Sardina, Marco

2018-02-01

Safinamide has been recently approved as an add-on to levodopa therapy for Parkinson disease. In addition to inhibiting monoamine oxidase type B, it blocks sodium channels and modulates glutamate (Glu) release in vitro. Since this property might contribute to the therapeutic action of the drug, we undertook the present study to investigate whether safinamide inhibits Glu release also in vivo and whether this effect is consistent across different brain areas and is selective for glutamatergic neurons. To this aim, in vivo microdialysis was used to monitor the spontaneous and veratridine-induced Glu and GABA release in the hippocampus and basal ganglia of naive, awake rats. Brain levels of safinamide were measured as well. To shed light on the mechanisms underlying the effect of safinamide, sodium currents were measured by patch-clamp recording in rat cortical neurons. Safinamide maximally inhibited the veratridine-induced Glu and GABA release in hippocampus at 15 mg/kg, which reached free brain concentrations of 1.89-1.37 µ M. This dose attenuated veratridine-stimulated Glu (but not GABA) release in subthalamic nucleus, globus pallidus, and substantia nigra reticulata, but not in striatum. Safinamide was ineffective on spontaneous neurotransmitter release. In vitro, safinamide inhibited sodium channels, showing a greater affinity at depolarized (IC 50 = 8 µ M) than at resting (IC 50 = 262 µ M) potentials. We conclude that safinamide inhibits in vivo Glu release from stimulated nerve terminals, likely via blockade of sodium channels at subpopulations of neurons with specific firing patterns. These data are consistent with the anticonvulsant and antiparkinsonian actions of safinamide and provide support for the nondopaminergic mechanism of its action. Copyright © 2018 The Author(s).

Quantitative evaluation of the neuroprotective effects of thiopental sodium, propofol, and halothane on brain ischemia in the gerbil: effects of the anesthetics on ischemic depolarization and extracellular glutamate concentration.

PubMed

Kobayashi, Motomu; Takeda, Yoshimasa; Taninishi, Hideki; Takata, Ken; Aoe, Hisami; Morita, Kiyoshi

2007-07-01

Although propofol and thiopental are commonly used as neuroprotective agents, it has not been determined which is more neuroprotective. This study was designed to quantitatively evaluate the neuroprotective effects of thiopental, propofol, and halothane on brain ischemia by determining P50, ischemic time necessary for causing 50% neuronal damage. Gerbils were anesthetized with thiopental, propofol, or halothane and underwent 2-vessel occlusion (0, 3, 5 or 10 min). Direct current potentials were measured in bilateral CA1 regions, in which histologic evaluation was performed 5 days later. In some animals, extracellular glutamate concentrations (microdialysis) were measured during 7.5 minutes of ischemia. P50 in the thiopental, propofol, and halothane groups were estimated to be 8.4, 6.5 (P<0.05, vs. thiopental), and 5.1 (P<0.05) minutes, respectively. Durations of ischemic depolarization were equally reduced in the thiopental and propofol groups compared with that in the halothane group. Severity of neuronal damage with identical duration of ischemic depolarization was attenuated by thiopental compared with the effect of propofol. Maximum glutamate concentrations in the thiopental and propofol group were significantly reduced compared with that in the halothane groups but were comparable. By using P50, we found that the neuroprotective effect of thiopental was greater than that of propofol. Although duration of ischemic depolarization was equally reduced in thiopental and propofol groups, thiopental has a greater suppressive effect on neuronal injury during identical duration of ischemic depolarization than propofol does. Glutamate concentration during brain ischemia tended to be attenuated more by thiopental than by propofol, but it was not statistically significant.

Improvement of Neuroenergetics by Hypertonic Lactate Therapy in Patients with Traumatic Brain Injury Is Dependent on Baseline Cerebral Lactate/Pyruvate Ratio

PubMed Central

Quintard, Hervé; Patet, Camille; Zerlauth, Jean-Baptiste; Suys, Tamarah; Bouzat, Pierre; Pellerin, Luc; Meuli, Reto; Magistretti, Pierre J.

2016-01-01

Abstract Energy dysfunction is associated with worse prognosis after traumatic brain injury (TBI). Recent data suggest that hypertonic sodium lactate infusion (HL) improves energy metabolism after TBI. Here, we specifically examined whether the efficacy of HL (3h infusion, 30–40 μmol/kg/min) in improving brain energetics (using cerebral microdialysis [CMD] glucose as a main therapeutic end-point) was dependent on baseline cerebral metabolic state (assessed by CMD lactate/pyruvate ratio [LPR]) and cerebral blood flow (CBF, measured with perfusion computed tomography [PCT]). Using a prospective cohort of 24 severe TBI patients, we found CMD glucose increase during HL was significant only in the subgroup of patients with elevated CMD LPR >25 (n = 13; +0.13 [95% confidence interval (CI) 0.08–0.19] mmol/L, p < 0.001; vs. +0.04 [–0.05–0.13] in those with normal LPR, p = 0.33, mixed-effects model). In contrast, CMD glucose increase was independent from baseline CBF (coefficient +0.13 [0.04–0.21] mmol/L when global CBF was <32.5 mL/100 g/min vs. +0.09 [0.04–0.14] mmol/L at normal CBF, both p < 0.005) and systemic glucose. Our data suggest that improvement of brain energetics upon HL seems predominantly dependent on baseline cerebral metabolic state and support the concept that CMD LPR – rather than CBF – could be used as a diagnostic indication for systemic lactate supplementation following TBI. PMID:26421521

Detection and quantification of microRNA in cerebral microdialysate.

PubMed

Bache, Søren; Rasmussen, Rune; Rossing, Maria; Hammer, Niels Risør; Juhler, Marianne; Friis-Hansen, Lennart; Nielsen, Finn Cilius; Møller, Kirsten

2015-05-07

Secondary brain injury accounts for a major part of the morbidity and mortality in patients with spontaneous aneurysmal subarachnoid hemorrhage (SAH), but the pathogenesis and pathophysiology remain controversial. MicroRNAs (miRNAs) are important posttranscriptional regulators of complementary mRNA targets and have been implicated in the pathophysiology of other types of acute brain injury. Cerebral microdialysis is a promising tool to investigate these mechanisms. We hypothesized that miRNAs would be present in human cerebral microdialysate. RNA was extracted and miRNA profiles were established using high throughput real-time quantification PCR on the following material: 1) Microdialysate sampled in vitro from A) a solution of total RNA extracted from human brain, B) cerebrospinal fluid (CSF) from a neurologically healthy patient, and C) a patient with SAH; and 2) cerebral microdialysate and CSF sampled in vivo from two patients with SAH. MiRNAs were categorized according to their relative recovery (RR) and a pathway analysis was performed for miRNAs exhibiting a high RR in vivo. Seventy-one of the 160 miRNAs detected in CSF were also found in in vivo microdialysate from SAH patients. Furthermore specific miRNAs consistently exhibited either a high or low RR in both in vitro and in vivo microdialysate. Analysis of repeatability showed lower analytical variation in microdialysate than in CSF. MiRNAs are detectable in cerebral microdialysate; a large group of miRNAs consistently showed a high RR in cerebral microdialysate. Measurement of cerebral interstitial miRNA concentrations may aid in the investigation of secondary brain injury in neurocritical conditions.

Sleep Duration Varies as a Function of Glutamate and GABA in Rat Pontine Reticular Formation

PubMed Central

Watson, Christopher J.; Lydic, Ralph; Baghdoyan, Helen A.

2011-01-01

The oral part of the pontine reticular formation (PnO) is a component of the ascending reticular activating system and plays a role in the regulation of sleep and wakefulness. The PnO receives glutamatergic and GABAergic projections from many brain regions that regulate behavioral state. Indirect, pharmacological evidence has suggested that glutamatergic and GABAergic signaling within the PnO alters traits that characterize wakefulness and sleep. No previous studies have simultaneously measured endogenous glutamate and GABA from rat PnO in relation to sleep and wakefulness. The present study utilized in vivo microdialysis coupled on-line to capillary electrophoresis with laser-induced fluorescence to test the hypothesis that concentrations of glutamate and GABA in the PnO vary across the sleep/wake cycle. Concentrations of glutamate and GABA were significantly higher during wakefulness than during NREM sleep and REM sleep. Regression analysis revealed that decreases in glutamate and GABA accounted for a significant portion of the variance in the duration of NREM sleep and REM sleep episodes. These data provide novel support for the hypothesis that endogenous glutamate and GABA in the PnO contribute to the regulation of sleep duration. PMID:21679185

Therapeutic efficacy of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) against organophosphate intoxication.

PubMed

Bueters, Tjerk J H; Groen, Bas; Danhof, Meindert; IJzerman, Ad P; Van Helden, Herman P M

2002-11-01

The objective of the present study was to investigate whether reduction of central acetylcholine (ACh) accumulation by adenosine receptor agonists could serve as a generic treatment against organophosphate (OP) poisoning. The OPs studied were tabun ( O-ethyl- N-dimethylphosphoramidocyanidate), sarin (isopropylmethylphosphonofluoridate), VX ( O-ethyl- S-2-diisopropylaminoethylmethylphosphonothiolate) and parathion ( O, O-diethyl- O-(4-nitrophenyl)phosphorothioate). The efficacy of the adenosine A(1) receptor agonist N(6)-cyclopentyladenosine (CPA) against an OP intoxication was examined on the basis of the occurrence of clinical symptoms that are directly associated with such intoxication. CPA (1-2 mg/kg) effectively attenuated the cholinergic symptoms and prevented mortality in lethally tabun- or sarin-intoxicated rats. In contrast, CPA (2 mg/kg) proved to be ineffective against VX or parathion intoxication. Intracerebral microdialysis studies revealed that survival of sarin-poisoned and CPA-treated animals coincided with a minor elevation of extracellular ACh concentrations in the brain relative to the baseline value, whereas an 11-fold increase in transmitter levels was observed in animals not treated with CPA. In VX-intoxicated rats, however, the ACh amounts increased 18-fold, irrespective of treatment with CPA. The striatal acetylcholinesterase (AChE) activity following a lethal sarin intoxication was completely abolished in the vehicle-treated animals, whereas 10% and 60% AChE activity remained in animals treated with 2 mg/kg CPA 1 min after or 2 min prior to the poisoning, respectively. In VX-intoxicated animals the AChE activity in the brain was strongly reduced (striatum 10%, hippocampus 1%) regardless of the CPA treatment. These results demonstrate that CPA is highly effective against tabun or sarin poisoning, but fails to protect against VX or parathion. Survival and attenuation of clinical signs in tabun- or sarin-poisoned animals are associated with a reduction of ACh accumulation and with protection of AChE activity in the brain.

In vivo studies on insulin permeability of an immunoisolation device intended for islet transplantation using the microdialysis technique.

PubMed

Rafael, E; Wernerson, A; Arner, P; Tibell, A

1999-01-01

In this study, insulin was injected into Theracyte immunoisolation devices to analyze changes in the permeability of the device over time after implantation. The recovery of insulin was studied after subcutaneous implantation of the devices in rats, using the microdialysis technique. The area under the insulin concentration vs. time curves (AUC) after insulin injection in devices implanted 1 day previously did not differ significantly from the AUC after subcutaneous injection. At 1, 2 and 4 weeks after implantation, the recovery of insulin was significantly reduced, but at 3 months, the AUC was not significantly different from that in the control group. Histological examination showed that the number of vascular profiles within 15 microm of the device were significantly higher at 2, 4 weeks and 3 months after transplantation when compared to numbers at 1 week. The design of the device allows transplantation of cells at a chosen time point after its implantation. Delayed filling of the device would allow neovascularization of the device surface before graft implantation and we suggest that such a schedule might improve function of the encapsulated graft.

Effects of growth hormone-releasing hormone on sleep and brain interstitial fluid amyloid-β in an APP transgenic mouse model.

PubMed

Liao, Fan; Zhang, Tony J; Mahan, Thomas E; Jiang, Hong; Holtzman, David M

2015-07-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by impairment of cognitive function, extracellular amyloid plaques, intracellular neurofibrillary tangles, and synaptic and neuronal loss. There is substantial evidence that the aggregation of amyloid β (Aβ) in the brain plays a key role in the pathogenesis of AD and that Aβ aggregation is a concentration dependent process. Recently, it was found that Aβ levels in the brain interstitial fluid (ISF) are regulated by the sleep-wake cycle in both humans and mice; ISF Aβ is higher during wakefulness and lower during sleep. Intracerebroventricular infusion of orexin increased wakefulness and ISF Aβ levels, and chronic sleep deprivation significantly increased Aβ plaque formation in amyloid precursor protein transgenic (APP) mice. Growth hormone-releasing hormone (GHRH) is a well-documented sleep regulatory substance which promotes non-rapid eye movement sleep. GHRHR(lit/lit) mice that lack functional GHRH receptor have shorter sleep duration and longer wakefulness during light periods. The current study was undertaken to determine whether manipulating sleep by interfering with GHRH signaling affects brain ISF Aβ levels in APPswe/PS1ΔE9 (PS1APP) transgenic mice that overexpress mutant forms of APP and PSEN1 that cause autosomal dominant AD. We found that intraperitoneal injection of GHRH at dark onset increased sleep and decreased ISF Aβ and that delivery of a GHRH antagonist via reverse-microdialysis suppressed sleep and increased ISF Aβ. The diurnal fluctuation of ISF Aβ in PS1APP/GHRHR(lit/lit) mice was significantly smaller than that in PS1APP/GHRHR(lit/+) mice. However despite decreased sleep in GHRHR deficient mice, this was not associated with an increase in Aβ accumulation later in life. One of several possibilities for the finding is the fact that GHRHR deficient mice have GHRH-dependent but sleep-independent factors which protect against Aβ deposition. Copyright © 2014 Elsevier Inc. All rights reserved.

Blockade of glutamate release by botulinum neurotoxin type A in humans: A dermal microdialysis study

PubMed Central

da Silva, Larissa Bittencourt; Karshenas, Ali; Bach, Flemming W; Rasmussen, Sten; Arendt-Nielsen, Lars; Gazerani, Parisa

2014-01-01

BACKGROUND: The analgesic action of botulinum neurotoxin type A (BoNTA) has been linked to the blockade of peripheral release of neuropeptides and neurotransmitters in animal models; however, there is no direct evidence of this in humans. OBJECTIVES: To investigate the effect of BoNTA on glutamate release in humans, using an experimental model of pain and sensitization provoked by capsaicin plus mild heat. METHODS: Twelve healthy volunteers (six men, six women) were pretreated with BoNTA (10 U) on the volar forearm and with a saline control on the contralateral side. Dermal microdialysis was applied one week later to collect interstitial samples before and after the application of a capsaicin patch (8%) plus mild heat (40°C/60 min) to provoke glutamate release, pain and vasodilation. Samples were collected every hour for 3 h using linear microdialysis probes (10 mm, 100 kD). Dialysate was analyzed for glutamate concentration. Pain intensity and skin vasomotor reactions (temperature and blood flow changes) were also recorded. RESULTS: BoNTA significantly reduced glutamate release compared with saline (P<0.05). The provoked pain intensity was lower in the BoNTA-pretreated arm (P<0.01). The reduction in pain scores was not correlated with glutamate level. Cutaneous blood flow (P<0.05), but not cutaneous temperature (P≥0.05), was significantly reduced by BoNTA. There was a correlation between glutamate level and skin blood flow (r=0.58/P<0.05) but not skin temperature (P≥0.05). No differences according to sex were observed in any response. CONCLUSIONS: The present study provided the first direct evidence supporting the inhibitory effect of BoNTA on glutamate release in human skin, which is potentially responsible for some of the analgesic action of BoNTA. PMID:24851237

In vivo evaluation of glucose permeability of an immunoisolation device intended for islet transplantation: a novel application of the microdialysis technique.

PubMed

Rafael, E; Wernerson, A; Arner, P; Wu, G S; Tibell, A

1999-01-01

Immunoisolation devices consist of semipermeable membranes chosen to protect the islets from the immune system but still allow sufficient passage of nutrients, oxygen, and the therapeutic products, insulin. The exchange between the device and the microcirculation will influence the survival of the graft as well as the metabolic efficacy of the islet implant. Glucose is the important trigger factor for insulin secretion. In this study, we evaluate the in vivo glucose permeability of the Theracyte immunoisolation device at various times after implantation. Empty devices were implanted s.c. in rats. The glucose kinetics in the device was compared to that in the SC tissue during i.v. glucose tolerance tests (IVGTTs), using the microdialysis technique. In rats studied on day 1, or 1, 2, and 4 weeks after implantation, the peak glucose levels (Cmax) were significantly lower, the times-to-peak (TTP) were significantly longer, and the areas under the curve during the first 40 min (AUC(0-40)) were significantly smaller in the device than in the SC fat. However, at 3 months all parameters improved and Cmax, TTP, and AUC(0-40) in the device did not differ significantly from those measured in the SC fat. Thus, during the first 4 weeks the device constitutes a significant diffusion barrier, but at 3 months the exchange between the lumen of devices and the blood stream improves. Our data indicate that implantation of the device several months before transplantation of the cellular graft would improve the exchange across the membrane during the early posttransplant period. This should have positive effects on graft survival and function. We also suggest that microdialysis is a useful tool for evaluating the in vivo performance of macroencapsulation devices.

A novel microdialysis-dissolution/permeation system for testing oral dosage forms: A proof-of-concept study.

PubMed

Fong, Sophia Yui Kau; Poulsen, Jessie; Brandl, Martin; Bauer-Brandl, Annette

2017-01-01

A novel microdialysis-dissolution/permeation (M-D/P) system was developed for the biopharmaceutical assessment of oral drug formulations. This system consists of a side-by-side diffusion chamber, a microdialysis unit fixed within the dissolution chamber for continuous sampling, and a biomimetic Permeapad® as the intestinal barrier. In the M-D/P system, the concentration of the molecularly dissolved drug (with MWCO <20kDa) was measured over time in the dissolution compartment (representing the gastrointestinal tract) while the concentration of the permeated drug was measured in the acceptor compartment (representing the blood). The kinetics of both the dissolution process and the permeation process were simultaneously quantified under circumstances that mimic physiological conditions. For the current proof-of-concept study, hydrocortisone (HCS) in the form of slowly dissolving solvate crystals and buffer and the biorelevant fasted state simulated intestinal fluids (FaSSIF), were employed as the model drug and dissolution media, respectively. The applicability of the M-D/P system to dissolution and permeation profiling of HCS in buffer and in FaSSIF has been successfully demonstrated. Compared to the conventional direct sampling method (using filter of 0.1-0.45μm), sampling by the M-D/P system exhibited distinct advantages, including (1) showing minimal disturbance of the permeation process, (2) differentiating "molecularly" dissolved drugs from "apparently" dissolved drugs during dissolution of HCS in FaSSIF, and (3) being less laborious and having better sampling temporal resolution. M-D/P system appeared to be a promising, simple and routine tool that allows for the researchers' intensive comprehension of the interplay of dissolution and permeation thus helping for better oral formulation screening and as an ultimate goal, for better dosage forms assessment. Copyright © 2016. Published by Elsevier B.V.

Investigating local and long-range neuronal network dynamics by simultaneous optogenetics, reverse microdialysis and silicon probe recordings in vivo

PubMed Central

Taylor, Hannah; Schmiedt, Joscha T.; Çarçak, Nihan; Onat, Filiz; Di Giovanni, Giuseppe; Lambert, Régis; Leresche, Nathalie; Crunelli, Vincenzo; David, Francois

2014-01-01

Background The advent of optogenetics has given neuroscientists the opportunity to excite or inhibit neuronal population activity with high temporal resolution and cellular selectivity. Thus, when combined with recordings of neuronal ensemble activity in freely moving animals optogenetics can provide an unprecedented snapshot of the contribution of neuronal assemblies to (patho)physiological conditions in vivo. Still, the combination of optogenetic and silicone probe (or tetrode) recordings does not allow investigation of the role played by voltage- and transmitter-gated channels of the opsin-transfected neurons and/or other adjacent neurons in controlling neuronal activity. New method and results We demonstrate that optogenetics and silicone probe recordings can be combined with intracerebral reverse microdialysis for the long-term delivery of neuroactive drugs around the optic fiber and silicone probe. In particular, we show the effect of antagonists of T-type Ca2+ channels, hyperpolarization-activated cyclic nucleotide-gated channels and metabotropic glutamate receptors on silicone probe-recorded activity of the local opsin-transfected neurons in the ventrobasal thalamus, and demonstrate the changes that the block of these thalamic channels/receptors brings about in the network dynamics of distant somatotopic cortical neuronal ensembles. Comparison with existing methods This is the first demonstration of successfully combining optogenetics and neuronal ensemble recordings with reverse microdialysis. This combination of techniques overcomes some of the disadvantages that are associated with the use of intracerebral injection of a drug-containing solution at the site of laser activation. Conclusions The combination of reverse microdialysis, silicone probe recordings and optogenetics can unravel the short and long-term effects of specific transmitter- and voltage-gated channels on laser-modulated firing at the site of optogenetic stimulation and the actions that these manipulations exert on distant neuronal populations. PMID:25004203

Investigating local and long-range neuronal network dynamics by simultaneous optogenetics, reverse microdialysis and silicon probe recordings in vivo.

PubMed

Taylor, Hannah; Schmiedt, Joscha T; Carçak, Nihan; Onat, Filiz; Di Giovanni, Giuseppe; Lambert, Régis; Leresche, Nathalie; Crunelli, Vincenzo; David, Francois

2014-09-30

The advent of optogenetics has given neuroscientists the opportunity to excite or inhibit neuronal population activity with high temporal resolution and cellular selectivity. Thus, when combined with recordings of neuronal ensemble activity in freely moving animals optogenetics can provide an unprecedented snapshot of the contribution of neuronal assemblies to (patho)physiological conditions in vivo. Still, the combination of optogenetic and silicone probe (or tetrode) recordings does not allow investigation of the role played by voltage- and transmitter-gated channels of the opsin-transfected neurons and/or other adjacent neurons in controlling neuronal activity. We demonstrate that optogenetics and silicone probe recordings can be combined with intracerebral reverse microdialysis for the long-term delivery of neuroactive drugs around the optic fiber and silicone probe. In particular, we show the effect of antagonists of T-type Ca(2+) channels, hyperpolarization-activated cyclic nucleotide-gated channels and metabotropic glutamate receptors on silicone probe-recorded activity of the local opsin-transfected neurons in the ventrobasal thalamus, and demonstrate the changes that the block of these thalamic channels/receptors brings about in the network dynamics of distant somatotopic cortical neuronal ensembles. This is the first demonstration of successfully combining optogenetics and neuronal ensemble recordings with reverse microdialysis. This combination of techniques overcomes some of the disadvantages that are associated with the use of intracerebral injection of a drug-containing solution at the site of laser activation. The combination of reverse microdialysis, silicone probe recordings and optogenetics can unravel the short and long-term effects of specific transmitter- and voltage-gated channels on laser-modulated firing at the site of optogenetic stimulation and the actions that these manipulations exert on distant neuronal populations. Copyright © 2014. Published by Elsevier B.V.

Continuous monitoring of bisulfide variation in microdialysis effluents by on-line droplet-based microfluidic fluorescent sensor.

PubMed

Zhu, Xiaocui; Xu, Lei; Wu, Tongbo; Xu, Anqin; Zhao, Meiping; Liu, Shaorong

2014-05-15

We demonstrate a novel fluorescent sensor for real-time and continuous monitoring of the variation of bisulfide in microdialysis effluents by using a nanoparticle-glutathione-fluorescein isothiocyanate (AuNP-GSH-FITC) probe coupled with on-line droplet-based microfluidic chip. The AuNP-GSH-FITC fluorescent probe was firstly developed and used for bisulfide detection in bulk solution by quantitative real-time PCR, which achieved a linear working range from 0.1 μM to 5.0 μM and a limit of detection of ~50 nM. The response time was less than 2 min. With the aid of co-immobilized thiol-polyethylene glycol, the probe exhibited excellent stability and reproducibility in high salinity solutions, including artificial cerebrospinal fluids (aCSF). By adding 0.1% glyoxal to the probe solution, the assay allowed quantification of bisulfide in the presence of cysteine at the micro-molarity level. Using the AuNP-GSH-FITC probe, a droplet-based microfluidic fluorescent sensor was further constructed for online monitoring of bisulfide variation in the effluent of microdialysis. By using fluorescence microscope-charge-coupled device camera as the detector, the integrated microdialysis/microfluidic chip device achieved a detection limit of 2.0 μM and a linear response from 5.0 μM to 50 μM for bisulfide in the tested sample. The method was successfully applied for the on-line measurement of bisulfide variation in aCSF and serum samples. It will be a very useful tool for tracking the variation of bisulfide or hydrogen sulfide in extracellular fluids. Copyright © 2013 Elsevier B.V. All rights reserved.

Neurotensin analog selective for hypothermia over antinociception and exhibiting atypical neuroleptic-like properties.

PubMed

Boules, M; McMahon, B; Warrington, L; Stewart, J; Jackson, J; Fauq, A; McCormick, D; Richelson, E

2001-11-16

Neurotensin (NT) is a tridecapeptide neurotransmitter in the central nervous system. It has been implicated in the therapeutic effects of neuroleptics. Central activity of NT can only be demonstrated by direct injection into the brain, since it is readily degraded by peptidases in the periphery. We have developed many NT(8-13) analogs that are resistant to peptidase degradation and can cross the blood-brain barrier (BBB). In this study, we report on one of these analogs, NT77L. NT77L induced hypothermia (ED(50)=6.5 mg/kg, i.p.) but induced analgesia only at the highest dose examined (20 mg/kg, i.p.). Like the atypical neuroleptic clozapine, NT77L blocked the climbing behavior in rats induced by the dopamine agonist apomorphine (600 microg/kg) with an ED(50) of 5.6 mg/kg (i.p.), without affecting the licking and the sniffing behaviors. By itself NT77L did not cause catalepsy, but it moderately reversed haloperidol-induced catalepsy with an ED(50) of 6.0 mg/kg (i.p.). Haloperidol alone did not lower body temperature, but it potentiated the body temperature lowering effect of NT77L. In studies using in vivo microdialysis NT77L showed similar effects on dopamine turnover to those of clozapine, and significantly different from those of haloperidol in the striatum. In the prefrontal cortex, NT77L significantly increased serotonergic transmission as evidenced by increased 5-hydroxyindole acetic acid:5-hydroxytryptamine (5-HIAA:5-HT) ratio. Thus, NT77L selectively caused hypothermia, over antinociception, while exhibiting atypical neuroleptic-like effects.

Brain kinetics of methylphenidate (Ritalin) enantiomers after oral administration.

PubMed

Ding, Yu-Shin; Gatley, S John; Thanos, Panayotis K; Shea, Colleen; Garza, Victor; Xu, Youwen; Carter, Pauline; King, Payton; Warner, Don; Taintor, Nicholas B; Park, Daniel J; Pyatt, Bea; Fowler, Joanna S; Volkow, Nora D

2004-09-01

Methylphenidate (MP) (Ritalin) is widely used for the treatment of attention deficit hyperactivity disorder (ADHD). It is a chiral drug, marketed as the racemic mixture of d- and l-threo enantiomers. Our previous studies (PET and microdialysis) in humans, baboons, and rats confirm the notion that pharmacological specificity of MP resides predominantly in the d-isomer. A recent report that intraperitoneally (i.p.) administered l-threo-MP displayed potent, dose-dependent inhibition of cocaine- or apomorphine-induced locomotion in rats, raises the question of whether l-threo-MP has a similar effect when given orally. It has been speculated that l-threo-MP is poorly absorbed in humans when it is given orally because of rapid presystemic metabolism. To investigate whether l-threo-MP or its metabolites can be delivered to the brain when it is given orally, and whether l-threo-MP is pharmacologically active. PET and MicroPET studies were carried out in baboons and rats using orally delivered C-11-labeled d- and l-threo-MP ([methyl-(11)C]d-threo-MP and [methyl-(11)C]l-threo-MP). In addition, we assessed the effects of i.p. l-threo-MP on spontaneous and cocaine-stimulated locomotor activity in mice. There was a higher global uptake of carbon-11 in both baboon and rat brain for oral [(11)C]l-threo-MP than for oral [(11)C]d-threo-MP. Analysis of the chemical form of radioactivity in rat brain after [(11)C]d-threo-MP indicated mainly unchanged tracer, whereas with [(11)C]l-threo-MP, it was mainly a labeled metabolite. The possibility that this labeled metabolite might be [(11)C]methanol or [(11)C]CO(2), derived from demethylation, was excluded by ex vivo studies in rats. When l-threo-MP was given i.p. to mice at a dose of 3 mg/kg, it neither stimulated locomotor activity nor inhibited the increased locomotor activity due to cocaine administration. These results suggest that, in animal models, l-threo-MP or its metabolite(s) is (are) absorbed from the gastrointestinal tract and enters the brain after oral administration, but that l-threo-MP may not be pharmacologically active. These results are pertinent to the question of whether l-threo-MP contributes to the behavioral and side effect profile of MP during treatment of ADHD. Copyright 2004 Wiley-Liss, Inc.

Music and Methamphetamine: Conditioned Cue-induced Increases in Locomotor Activity and Dopamine Release in Rats

PubMed Central

Polston, J.E.; Rubbinaccio, H.Y.; Morra, J.T.; Sell, E.M.; Glick, S.D.

2011-01-01

Associations between drugs of abuse and cues facilitate the acquisition and maintenance of addictive behaviors. Although significant research has been done to elucidate the role that simple discriminative or discrete conditioned stimuli (e.g., a tone or a light) play in addiction, less is known about complex environmental cues. The purpose of the present study was to examine the role of a musical conditioned stimulus by assessing locomotor activity and in vivo microdialysis. Two groups of rats were given non-contingent injections of methamphetamine (1.0 mg/kg) or vehicle and placed in standard conditioning chambers. During these conditioning sessions both groups were exposed to a continuous conditioned stimulus, in the form of a musical selection (“Four” by Miles Davis) played repeatedly for ninety minutes. After seven consecutive conditioning days subjects were given one day of rest, and subsequently tested for locomotor activity or dopamine release in the absence of drug while the musical conditioned stimulus was continually present. The brain regions examined included the basolateral amygdala, nucleus accumbens, and prefrontal cortex. The results show that music is an effective contextual conditioned stimulus, significantly increasing locomotor activity after repeated association with methamphetamine. Furthermore, this musical conditioned stimulus significantly increased extracellular dopamine levels in the basolateral amygdala and nucleus accumbens. These findings support other evidence showing the importance of these brain regions in conditioned learning paradigms, and demonstrate that music is an effective conditioned stimulus warranting further investigation. PMID:21145911

GLT-1-Dependent Disruption of CNS Glutamate Homeostasis and Neuronal Function by the Protozoan Parasite Toxoplasma gondii

PubMed Central

David, Clément N.; Frias, Elma S.; Szu, Jenny I.; Vieira, Philip A.; Hubbard, Jacqueline A.; Lovelace, Jonathan; Michael, Marena; Worth, Danielle; McGovern, Kathryn E.; Ethell, Iryna M.; Stanley, B. Glenn; Korzus, Edward; Fiacco, Todd A.; Binder, Devin K.; Wilson, Emma H.

2016-01-01

The immune privileged nature of the CNS can make it vulnerable to chronic and latent infections. Little is known about the effects of lifelong brain infections, and thus inflammation, on the neurological health of the host. Toxoplasma gondii is a parasite that can infect any mammalian nucleated cell with average worldwide seroprevalence rates of 30%. Infection by Toxoplasma is characterized by the lifelong presence of parasitic cysts within neurons in the brain, requiring a competent immune system to prevent parasite reactivation and encephalitis. In the immunocompetent individual, Toxoplasma infection is largely asymptomatic, however many recent studies suggest a strong correlation with certain neurodegenerative and psychiatric disorders. Here, we demonstrate a significant reduction in the primary astrocytic glutamate transporter, GLT-1, following infection with Toxoplasma. Using microdialysis of the murine frontal cortex over the course of infection, a significant increase in extracellular concentrations of glutamate is observed. Consistent with glutamate dysregulation, analysis of neurons reveal changes in morphology including a reduction in dendritic spines, VGlut1 and NeuN immunoreactivity. Furthermore, behavioral testing and EEG recordings point to significant changes in neuronal output. Finally, these changes in neuronal connectivity are dependent on infection-induced downregulation of GLT-1 as treatment with the ß-lactam antibiotic ceftriaxone, rescues extracellular glutamate concentrations, neuronal pathology and function. Altogether, these data demonstrate that following an infection with T. gondii, the delicate regulation of glutamate by astrocytes is disrupted and accounts for a range of deficits observed in chronic infection. PMID:27281462

Non-invasive determination of glucose directly in raw fruits using a continuous flow system based on microdialysis sampling and amperometric detection at an integrated enzymatic biosensor.

PubMed

Vargas, E; Ruiz, M A; Campuzano, S; Reviejo, A J; Pingarrón, J M

2016-03-31

A non-destructive, rapid and simple to use sensing method for direct determination of glucose in non-processed fruits is described. The strategy involved on-line microdialysis sampling coupled with a continuous flow system with amperometric detection at an enzymatic biosensor. Apart from direct determination of glucose in fruit juices and blended fruits, this work describes for the first time the successful application of an enzymatic biosensor-based electrochemical approach to the non-invasive determination of glucose in raw fruits. The methodology correlates, through previous calibration set-up, the amperometric signal generated from glucose in non-processed fruits with its content in % (w/w). The comparison of the obtained results using the proposed approach in different fruits with those provided by other method involving the same commercial biosensor as amperometric detector in stirred solutions pointed out that there were no significant differences. Moreover, in comparison with other available methodologies, this microdialysis-coupled continuous flow system amperometric biosensor-based procedure features straightforward sample preparation, low cost, reduced assay time (sampling rate of 7 h(-1)) and ease of automation. Copyright © 2016 Elsevier B.V. All rights reserved.

Integration of Microdialysis Sampling and Microchip Electrophoresis with Electrochemical Detection

PubMed Central

Mecker, Laura C.; Martin, R. Scott

2009-01-01

Here we describe the fabrication, optimization, and application of a microfluidic device that integrates microdialysis (MD) sampling, microchip electrophoresis (ME), and electrochemical detection (EC). The manner in which the chip is produced is reproducible and enables the fixed alignment of the MD/ME and ME/EC interfaces. Poly(dimethylsiloxane) (PDMS) -based valves were used for the discrete injection of sample from the hydrodynamic MD dialysate stream into a separation channel for analysis with ME. To enable the integration of ME with EC detection, a palladium decoupler was used to isolate the high voltages associated with electrophoresis from micron-sized carbon ink detection electrodes. Optimization of the ME/EC interface was needed to allow the use of biologically appropriate perfusate buffers containing high salt content. This optimization included changes in the fabrication procedure, increases in the decoupler surface area, and a programmed voltage shutoff. The ability of the MD/ME/EC system to sample a biological system was demonstrated by using a linear probe to monitor the stimulated release of dopamine from a confluent layer of PC 12 cells. To our knowledge, this is the first report of a microchip-based system that couples microdialysis sampling with microchip electrophoresis and electrochemical detection. PMID:19551945

Site-specific activation of dopamine and serotonin transmission by aniracetam in the mesocorticolimbic pathway of rats.

PubMed

Nakamura, K; Shirane, M; Koshikawa, N

2001-04-06

The effects of aniracetam on extracellular levels of dopamine (DA), serotonin (5-HT) and their metabolites were examined in five brain regions in freely moving stroke-prone spontaneously hypertensive rats (SHRSP) using in vivo microdialysis. Basal DA release in SHRSP was uniformly lower in all regions tested than that in age-matched control Wistar Kyoto rats. 3,4-Dihydroxyphenylacetic acid and homovanillic acid levels were altered in the basolateral amygdala, dorsal hippocampus and prefrontal cortex of SHRSP. While basal 5-HT release decreased in the striatum and increased in the basolateral amygdala, there was no associated change in 5-hydroxyindoleacetic acid levels. Systemic administration of aniracetam to SHRSP enhanced both DA and 5-HT release with partly associated change in their metabolite levels in the prefrontal cortex, basolateral amygdala and dorsal hippocampus, but not in the striatum and nucleus accumbens shell, in a dose-dependent manner (30 and/or 100 mg/kg p.o.). Microinjection (1 and 10 ng) of aniracetam or its metabolites (N-anisoyl-GABA and 2-pyrrolidinone) into the nucleus accumbens shell produced no turning behavior. These findings indicate that SHRSP have a dopaminergic hypofunction throughout the brain and that aniracetam elicits a site-specific activation in mesocorticolimbic dopaminergic and serotonergic pathways in SHRSP, possibly via nicotinic acetylcholine receptors in the ventral tegmental area and raphe nuclei. The physiological roles in the aniracetam-sensitive brain regions may closely link with their clinical efficacy towards emotional disturbances appearing after cerebral infarction.

Regional Differential Effects of the Novel Histamine H3 Receptor Antagonist 6-[(3-Cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-N-methyl-3-pyridinecarboxamide hydrochloride (GSK189254) on Histamine Release in the Central Nervous System of Freely Moving Rats

PubMed Central

Giannoni, Patrizia; Medhurst, Andrew D.; Passani, Maria Beatrice; Giovannini, Maria Grazia; Ballini, Chiara; Corte, Laura Della

2010-01-01

After oral administration, the nonimidazole histamine H3 receptor antagonist, 6-[(3-cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-N-methyl-3-pyridinecarboxamide hydrochloride (GSK189254), increased histamine release from the tuberomammillary nucleus, where all histaminergic somata are localized, and from where their axons project to the entire brain. To further understand functional histaminergic circuitry in the brain, dual-probe microdialysis was used to pharmacologically block H3 receptors in the tuberomammillary nucleus, and monitor histamine release in projection areas. Perfusion of the tuberomammillary nucleus with GSK189254 increased histamine release from the tuberomammillary nucleus, nucleus basalis magnocellularis, and cortex, but not from the striatum or nucleus accumbens. Cortical acetylcholine (ACh) release was also increased, but striatal dopamine release was not affected. When administered locally, GSK189254 increased histamine release from the nucleus basalis magnocellularis, but not from the striatum. Thus, defined by their sensitivity to GSK189254, histaminergic neurons establish distinct pathways according to their terminal projections, and can differentially modulate neurotransmitter release in a brain region-specific manner. Consistent with its effects on cortical ACh release, systemic administration of GSK189254 antagonized the amnesic effects of scopolamine in the rat object recognition test, a cognition paradigm with important cortical components. PMID:19815811

Development of a population pharmacokinetic model to predict brain distribution and dopamine D2 receptor occupancy of raclopride in non-anesthetized rat.

PubMed

Wong, Yin Cheong; Ilkova, Trayana; van Wijk, Rob C; Hartman, Robin; de Lange, Elizabeth C M

2018-01-01

Raclopride is a selective antagonist of the dopamine D2 receptor. It is one of the most frequently used in vivo D2 tracers (at low doses) for assessing drug-induced receptor occupancy (RO) in animals and humans. It is also commonly used as a pharmacological blocker (at high doses) to occupy the available D2 receptors and antagonize the action of dopamine or drugs on D2 in preclinical studies. The aims of this study were to comprehensively evaluate its pharmacokinetic (PK) profiles in different brain compartments and to establish a PK-RO model that could predict the brain distribution and RO of raclopride in the freely moving rat using a LC-MS based approach. Rats (n=24) received a 10-min IV infusion of non-radiolabeled raclopride (1.61μmol/kg, i.e. 0.56mg/kg). Plasma and the brain tissues of striatum (with high density of D2 receptors) and cerebellum (with negligible amount of D2 receptors) were collected. Additional microdialysis experiments were performed in some rats (n=7) to measure the free drug concentration in the extracellular fluid of the striatum and cerebellum. Raclopride concentrations in all samples were analyzed by LC-MS. A population PK-RO model was constructed in NONMEM to describe the concentration-time profiles in the unbound plasma, brain extracellular fluid and brain tissue compartments and to estimate the RO based on raclopride-D2 receptor binding kinetics. In plasma raclopride showed a rapid distribution phase followed by a slower elimination phase. The striatum tissue concentrations were consistently higher than that of cerebellum tissue throughout the whole experimental period (10-h) due to higher non-specific tissue binding and D2 receptor binding in the striatum. Model-based simulations accurately predicted the literature data on rat plasma PK, brain tissue PK and D2 RO at different time points after intravenous or subcutaneous administration of raclopride at tracer dose (RO <10%), sub-pharmacological dose (RO 10%-30%) and pharmacological dose (RO >30%). For the first time a predictive model that could describe the quantitative in vivo relationship between dose, PK and D2 RO of raclopride in non-anesthetized rat was established. The PK-RO model could facilitate the selection of optimal dose and dosing time when raclopride is used as tracer or as pharmacological blocker in various rat studies. The LC-MS based approach, which doses and quantifies a non-radiolabeled tracer, could be useful in evaluating the systemic disposition and brain kinetics of tracers. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Novel integrated microdialysis-amperometric system for in vitro detection of dopamine secreted from PC12 cells: design, construction, and validation.

PubMed

Migheli, Rossana; Puggioni, Giulia; Dedola, Sonia; Rocchitta, Gaia; Calia, Giammario; Bazzu, Gianfranco; Esposito, Giovanni; Lowry, John P; O'Neill, Robert D; Desole, M S; Miele, Egidio; Serra, Pier A

2008-09-15

A novel dual channel in vitro apparatus, derived from a previously described design, has been coupled with dopamine (DA) microsensors for the flow-through detection of DA secreted from PC12 cells. The device, including two independent microdialysis capillaries, was loaded with a solution containing PC12 cells while a constant phosphate-buffered saline (PBS) medium perfusion was carried out using a dual channel miniaturized peristaltic pump. One capillary was perfused with normal PBS, whereas extracellular calcium was removed from extracellular fluid of the second capillary. After a first period of stabilization and DA baseline recording, KCl (75 mM) was added to the perfusion fluid of both capillaries. In this manner, a simultaneous "treatment-control" experimental design was performed to detect K+-evoked calcium-dependent DA secretion. For this purpose, self-referencing DA microsensors were developed, and procedures for making, testing, and calibrating them are described in detail. The electronic circuitry was derived from previously published schematics and optimized for dual sensor constant potential amperometry applications. The microdialysis system was tested and validated in vitro under different experimental conditions, and DA secretion was confirmed by high-performance liquid chromatography with electrochemical detection (HPLC-EC). PC12 cell viability was quantified before and after each experiment. The proposed apparatus serves as a reliable model for studying the effects of different drugs on DA secretion through the direct comparison of extracellular DA increase in treatment-control experiments performed on the same initial PC12 cell population.

Neuropeptide Signaling in Crustaceans Probed by Mass Spectrometry

NASA Astrophysics Data System (ADS)

Liang, Zhidan

Neuropeptides are one of the most diverse classes of signaling molecules whose identities and functions are not yet fully understood. They have been implicated in the regulation of a wide range of physiological processes, including feeding-related and motivated behaviors, and also environmental adaptations. In this work, improved mass spectrometry-based analytical platforms were developed and applied to the crustacean systems to characterize signaling molecules. This dissertation begins with a review of mass spectrometry-based neuropeptide studies from both temporal- and spatial-domains. This review is then followed by several chapters detailing a few research projects related to the crustacean neuropeptidomic characterization and comparative analysis. The neuropeptidome of crayfish, Orconectes rusticus is characterized for the first time using mass spectrometry-based tools. In vivo microdialysis sampling technique offers the capability of direct sampling from extracellular space in a time-resolved manner. It is used to investigate the secreted neuropeptide and neurotransmitter content in Jonah crab, Cancer borealis, in this work. A new quantitation strategy using alternative mass spectrometry data acquisition approach is developed and applied for the first time to quantify neuropeptides. Coupling of this method with microdialysis enables the study of neuropeptide dynamics concurrent with different behaviors. Proof-of-principle experiments validating this approach have been carried out in Jonah crab, Cancer borealis to study feeding- and circadian rhythm-related neuropeptide changes using micoridialysis in a time-resolved manner. This permits a close correlation between behavioral and neurochemical changes, providing potential candidates for future validation of regulatory roles. In addition to providing spatial information, mass spectrometry imaging (MSI) technique enables the characterization of signaling molecules while preserving the temporal resolution. A novel MSI-based platform is developed by interfacing with microdialysis sample collection and is applied to the study of in vivo neuropeptide degradation profiles in an off-line 'real-time' fashion. This unique platform provides novel insights into neuropeptide inactivation/elimination process, which is an essential step to understand peptidergic signaling pathway. In addition to neuropeptides, this platform has been further modified to study secreted neurotransmitters, and small molecule metabolites that might interact with neuropeptides in crustacean for the first time. This work not only reports improvements upon neuropeptides identification and quantitation by developing improved analytical strategies, but also provides important evidence for the potential roles of several neuropeptides in regulating food intake and circadian rhythm behaviors. Novel platform that integrates MALDI-MSI with microdialysis in exploring neurochemical changes in dynamic biological events is also presented, which could be potentially applied to many other systems in future research. Collectively this dissertation research develops new analytical methods and improves our fundamental understanding of neuropeptide signaling.

Effects of COMT inhibitors on striatal dopamine metabolism: A microdialysis study

NASA Technical Reports Server (NTRS)

Kaakkola, S.; Wurtman, R. J.

1992-01-01

In vivo microdialysis was used to examine the effect of two new catechol-O-methyltransferase (COMT) inhibitors, Ro 40-7592 and OR-611, on extracellular levels of dopamine, dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in rat striatum. The interactions of the COMT inhibitors with nomifensine, clorgyline, and deprenyl were also studied. Ro 40-7592 (3-30 mg/kg. i.p.) decreased dose-dependently the efflux of HVA, increased that of DOPAC, and tended to increase that of dopamine. Higher doses of OR-611 (30-100 mg/kg, i.p.) also decreased the dialysate level of HVA, increased that of DOPAC, and tended to increase that of dopamine. Ro 40-7592 was about ten-fold as potent as OR-611. Neither of the COMT inhibitors changed dialysate levels of 6-HIAA. An OR-611 dose of 10 mg/kg i.p. had no significant effect, in contrast to Ro 40-7592, on any of the parameters studied; this dose was thus used to differentiate between the effects of central and peripheral COMT inhibition. Both nomifensine (15 mg/kg, i.p.) and clorgyline (4 mg/kg, i.p.) alone elevated extracellular dopamine levels, and lowered those of DOPAC and HVA, though there were quantitative and temporal differences between the drugs. L-deprenyl (1 mg/kg, i.p.) alone had no significant effect on any of the compounds measured. Ro 40-7592 (10 mg/kg, i.p.) potentiated the effect of nomifensine on dopamine efflux, and it tended to increase clorgyline-induced dopamine efflux. DOPAC levels in dialysates were significantly increased by combinations of Ro 40-7592 and nomifensine or clorgyline, whereas HVA remained about as low as they were after Ro 40-7592 alone. Ro 40-7592 had no significant interactions with L-deprenyl. OR-611 (10 mg/kg, i.p.) did not modify the effects on dopamine metabolism of nomifensine, clorgyline, or L-deprenyl. These data show that Ro 40-7592 is a potent centrally active COMT inhibitor, whereas OR-611 is principally a peripherally active inhibitor. Use of drugs which inhibit brain COMT can considerably modify dopamine metabolism. COMT inhibitors may be of clinical significance in treating Parkinson's disease.

S-(N, N-diethylcarbamoyl)glutathione (carbamathione), a disulfiram metabolite and its effect on nucleus accumbens and prefrontal cortex dopamine, GABA, and glutamate: A microdialysis study

PubMed Central

Faiman, Morris D.; Kaul, Swetha; Latif, Shaheen A.; Williams, Todd D.; Lunte, Craig E.

2015-01-01

Disulfiram (DSF), used for the treatment of alcohol use disorders (AUDs) for over six decades, most recently has shown promise for treating cocaine dependence. Although DSF’s mechanism of action in alcohol abuse is due to the inhibition of liver mitochondrial aldehyde dehydrogenase (ALDH2), its mechanism of action in the treatment of cocaine dependence is unknown. DSF is a pro-drug, forming a number of metabolites each with discrete pharmacological actions. One metabolite formed during DSF bioactivation is S-(N, N-diethylcarbamoyl) glutathione (carbamathione) (carb). We previously showed that carb affects glutamate binding. In the present studies, we employed microdialysis techniques to investigate the effect of carb administration on dopamine (DA), GABA, and glutamate (Glu) in the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC), two brain regions implicated in substance abuse dependence. The effect of DSF on DA, GABA, and Glu in the NAc also was determined. Both studies were carried out in male rats. Carb (20, 50, 200 mg/kg i v) in a dose-dependent manner increased DA, decreased GABA, and had a biphasic effect on Glu, first increasing and then decreasing Glu in both the NAc and mPFC. These changes all occurred concurrently. After carb administration, NAc and mPFC carb, as well as carb in plasma, were rapidly eliminated with a half-life for each approximately 4 min, while the changes in DA, GABA, and GLu in the NAc and mPFC persisted for approximately two hours. The maximal increase in carb (Cmax) in the NAc and mPFC after carb administration was dose-dependent, as was the area under the curve (AUC). DSF (200 mg/kg i p) also increased DA, decreased GABA, and had a biphasic effect on Glu in the NAc similar to that observed in the NAc after carb administration. When the cytochrome P450 inhibitor N-benzylimidazole (NBI) (20 mg/kg i p) was administered before DSF dosing, no carb could be detected in the NAc and plasma and also no changes in NAc DA, GABA, and GLu occurred. Changes in these neurotransmitters occurred only if carb was formed from DSF. When NBI was administered prior to dosing with carb, the increase in DA, decrease in GABA, and biphasic effect on GLu was similar to that seen after dosing with carb only. The i p or i v administration of carb showed similar changes in DA, GABA, and GLu, except the time to reach Cmax for DA as well as the changes in GABA, and GLu after i p administration occurred later. The elimination half-life of carb and the area under the curve (AUC) were similar after both routes of administration. It is concluded that carb must be formed from DSF before any changes in DA, GABA, and GLu in the NAc and mPFC are observed. DSF and carb, when administered to rats, co-release DA, GABA, and GLu. Carb, once formed can cross the blood brain barrier and enter the brain. Although inhibition of liver ALDH2 is the accepted mechanism for DSF’s action in treating AUDs, the concurrent changes in DA, GABA, and GLu in the NAc and mPFC after DSF administration suggest that changes in these neurotransmitters as a potential mechanism of action not only for AUDs, but also for cocaine dependence cannot be excluded. PMID:23891816

Toward continuous glucose monitoring with planar modified biosensors and microdialysis. Study of temperature, oxygen dependence and in vivo experiment.

PubMed

Ricci, Francesco; Caprio, Felice; Poscia, Alessandro; Valgimigli, Francesco; Messeri, Dimitri; Lepori, Elena; Dall'Oglio, Giorgio; Palleschi, Giuseppe; Moscone, Danila

2007-04-15

Glucose biosensors based on the use of planar screen-printed electrodes modified with an electrochemical mediator and with glucose oxidase have been optimised for their application in the continuous glucose monitoring in diabetic patients. A full study of their operative stability and temperature dependence has been accomplished, thus giving useful information for in vivo applications. The effect of dissolved oxygen concentration in the working solution was also studied in order to evaluate its effect on the linearity of the sensors. Glucose monitoring performed with serum samples was performed to evaluate the effect of matrix components on operative stability and demonstrated an efficient behaviour for 72 h of continuous monitoring. Finally, these studies led to a sensor capable of detecting glucose at concentrations as low as 0.04 mM and with a good linearity up to 2.0 mM (at 37 degrees C) with an operative stability of ca. 72 h, thus demonstrating the possible application of these sensors for continuous glucose monitoring in conjunction with a microdialysis probe. Moreover, preliminary in vivo experiments for ca. 20 h have demonstrated the feasibility of this system.

Neurogenetics of Aggressive Behavior – Studies in Rodents

PubMed Central

Takahashi, Aki; Miczek, Klaus A.

2014-01-01

Aggressive behavior is observed in many animal species, such as insects, fish, lizards, frogs, and most mammals including humans. This wide range of conservation underscores the importance of aggressive behavior in the animals’ survival and fitness, and the likely heritability of this behavior. Although typical patterns of aggressive behavior differ between species, there are several concordances in the neurobiology of aggression among rodents, primates, and humans. Studies with rodent models may eventually help us to understand the neurogenetic architecture of aggression in humans. However, it is important to recognize the difference between the ecological and ethological significance of aggressive behavior (species-typical aggression) and maladaptive violence (escalated aggression) when applying the findings of aggression research using animal models to human or veterinary medicine. Well-studied rodent models for aggressive behavior in the laboratory setting include the mouse (Mus musculus), rat (Rattus norvegicus), hamster (Mesocricetus auratus), and prairie vole (Microtus ochrogaster). The neural circuits of rodent aggression have been gradually elucidated by several techniques e.g. immunohistochemistry of immediate-early gene (c-Fos) expression, intracranial drug microinjection, in vivo microdialysis, and optogenetics techniques. Also, evidence accumulated from the analysis of gene-knockout mice shows the involvement of several genes in aggression. Here we review the brain circuits that have been implicated in aggression, such as the hypothalamus, prefrontal cortex (PFC), dorsal raphe nucleus (DRN), nucleus accumbens (NAc), and olfactory system. We then discuss the roles of glutamate and γ-aminobutyric acid (GABA), major inhibitory and excitatory amino acids in the brain, as well as their receptors, in controlling aggressive behavior, focusing mainly on recent findings. At the end of this chapter, we discuss how genes can be identified that underlie individual differences in aggression, using the so-called forward genetics approach. PMID:24318936

Prefrontal Norepinephrine Determines Attribution of “High” Motivational Salience

PubMed Central

Ventura, Rossella; Latagliata, Emanuele Claudio; Morrone, Cristina; La Mela, Immacolata; Puglisi-Allegra, Stefano

2008-01-01

Intense motivational salience attribution is considered to have a major role in the development of different psychopathologies. Numerous brain areas are involved in “normal” motivational salience attribution processes; however, it is not clear whether common or different neural mechanisms also underlie intense motivational salience attribution. To elucidate this a brain area and a neural system had to be envisaged that were involved only in motivational salience attribution to highly salient stimuli. Using intracerebral microdialysis, we found that natural stimuli induced an increase in norepinephrine release in the medial prefrontal cortex of mice proportional to their salience, and that selective prefrontal norepinephrine depletion abolished the increase of norepinephrine release in the medial prefrontal cortex induced by exposure to appetitive (palatable food) or aversive (light) stimuli independently of salience. However, selective norepinephrine depletion in the medial prefrontal cortex impaired the place conditioning induced exclusively by highly salient stimuli, thus indicating that prefrontal noradrenergic transmission determines approach or avoidance responses to both reward- and aversion-related natural stimuli only when the salience of the unconditioned natural stimulus is high enough to induce sustained norepinephrine outflow. This affirms that prefrontal noradrenergic transmission determines motivational salience attribution selectively when intense motivational salience is processed, as in conditions that characterize psychopathological outcomes. PMID:18725944

Clozapine and GABA transmission in schizophrenia disease models: establishing principles to guide treatments.

PubMed

O'Connor, William T; O'Shea, Sean D

2015-06-01

Schizophrenia disease models are necessary to elucidate underlying changes and to establish new therapeutic strategies towards a stage where drug efficacy in schizophrenia (against all classes of symptoms) can be predicted. Here we summarise the evidence for a GABA dysfunction in schizophrenia and review the functional neuroanatomy of five pathways implicated in schizophrenia, namely the mesocortical, mesolimbic, ventral striopallidal, dorsal striopallidal and perforant pathways including the role of local GABA transmission and we describe the effect of clozapine on local neurotransmitter release. This review also evaluates psychotropic drug-induced, neurodevelopmental and environmental disease models including their compatibility with brain microdialysis. The validity of disease models including face, construct, etiological and predictive validity and how these models constitute theories about this illness is also addressed. A disease model based on the effect of the abrupt withdrawal of clozapine on GABA release is also described. The review concludes that while no single animal model is entirely successful in reproducing schizophreniform symptomatology, a disease model based on an ability to prevent and/or reverse the abrupt clozapine discontinuation-induced changes in GABA release in brain regions implicated in schizophrenia may be useful for hypothesis testing and for in vivo screening of novel ligands not limited to a single pharmacological class. Copyright © 2015 Elsevier Inc. All rights reserved.

Design of a dynamic optical tissue phantom to model extravasation pharmacokinetics

NASA Astrophysics Data System (ADS)

Zhang, Jane Y.; Ergin, Aysegul; Andken, Kerry Lee; Sheng, Chao; Bigio, Irving J.

2010-02-01

We describe an optical tissue phantom that enables the simulation of drug extravasation from microvessels and validates computational compartmental models of drug delivery. The phantom consists of a microdialysis tubing bundle to simulate the permeable blood vessels, immersed in either an aqueous suspension of titanium dioxide (TiO2) or a TiO2 mixed agarose scattering medium. Drug administration is represented by a dye circulated through this porous microdialysis tubing bundle. Optical pharmacokinetic (OP) methods are used to measure changes in the absorption coefficient of the scattering medium due to the arrival and diffusion of the dye. We have established particle sizedependent concentration profiles over time of phantom drug delivery by intravenous (IV) and intra-arterial (IA) routes. Additionally, pharmacokinetic compartmental models are implemented in computer simulations for the conditions studied within the phantom. The simulated concentration-time profiles agree well with measurements from the phantom. The results are encouraging for future optical pharmacokinetic method development, both physical and computational, to understand drug extravasation under various physiological conditions.

A ketogenic diet modifies glutamate, gamma-aminobutyric acid and agmatine levels in the hippocampus of rats: A microdialysis study.

PubMed

Calderón, Naima; Betancourt, Luis; Hernández, Luis; Rada, Pedro

2017-03-06

The ketogenic diet (KD) is acknowledged as an unconventional option in the treatment of epilepsy. Several lines of investigation point to a possible role of glutamate and gamma-aminobutyric acid (GABA) as main contributors in this protective effect. Other biomolecules could also be involved in the beneficial consequence of the KD, for example, the diamine agmatine has been suggested to block imidazole and glutamate NMDA receptor and serves as an endogenous anticonvulsant in different animal models of epilepsy. In the present report, we have used microdialysis coupled to capillary electrophoresis to monitor microdialysate levels of GABA, glutamate and agmatine in the hippocampus of rats submitted to a KD for 15days compared to rats on a normal rat chow diet. A significant increase in GABA and agmatine levels while no change in glutamate levels was observed. These results support the notion that the KD modifies different transmitters favoring inhibitory over excitatory neurotransmitters. Copyright © 2017 Elsevier B.V. All rights reserved.

Sodium ion transport participates in non-neuronal acetylcholine release in the renal cortex of anesthetized rabbits.

PubMed

Shimizu, Shuji; Akiyama, Tsuyoshi; Kawada, Toru; Sata, Yusuke; Turner, Michael James; Fukumitsu, Masafumi; Yamamoto, Hiromi; Kamiya, Atsunori; Shishido, Toshiaki; Sugimachi, Masaru

2017-09-01

This study examined the mechanism of release of endogenous acetylcholine (ACh) in rabbit renal cortex by applying a microdialysis technique. In anesthetized rabbits, a microdialysis probe was implanted into the renal cortex and perfused with Ringer's solution containing high potassium concentration, high sodium concentration, a Na + /K + -ATPase inhibitor (ouabain), or an epithelial Na + channel blocker (benzamil). Dialysate samples were collected at baseline and during exposure to each agent, and ACh concentrations in the samples were measured by high-performance liquid chromatography. High potassium had no effect on renal ACh release. High sodium increased dialysate ACh concentrations significantly. Ouabain increased dialysate ACh concentration significantly. Benzamil decreased dialysate ACh concentrations significantly both at baseline and under high sodium. The finding that high potassium-induced depolarization does not increase ACh release suggests that endogenous ACh is released in renal cortex mainly by non-neuronal mechanism. Sodium ion transport may be involved in the non-neuronal ACh release.

Sexual odor preference and dopamine release in the nucleus accumbens by estrous olfactory cues in sexually naïve and experienced male rats.

PubMed

Fujiwara, Masaya; Chiba, Atsuhiko

2018-03-01

Sexual behavior is a natural reward that activates mesolimbic dopaminergic system. Microdialysis studies have shown that extracellular level of dopamine (DA) in the nucleus accumbens (NAcc) significantly increases during copulation in male rats. The NAcc DA level is also known to be increased during the presentation of a sexually receptive female before mating. This rise in DA was probably associated with sexual motivation elicited by incentive stimuli from the receptive female. These microdialysis studies, however, did not thoroughly investigated if olfactory stimuli from estrous females could significantly increase the extracellular DA in the NAcc of male rats. The present study was designed to examine systematically the relationship between the expression of preference for the olfactory stimuli from estrous females and the effects of these stimuli on the extracellular DA levels in the NAcc measured by in vivo microdialysis in male Long-Evans (LE) rats. We used two types of olfactory stimuli, either airborne odors (volatile stimuli) or soiled bedding (volatile plus nonvolatile stimuli). The sexually experienced male rats, which experienced six ejaculations, significantly preferred both of these olfactory stimuli from estrous females as opposed to males. Exposure to these female olfactory stimuli gradually increased extracellular DA in the NAcc, which reached significantly higher level above baseline during the period following the removal of the stimuli although not during the 15-min stimulus presentation period. The sexually naïve male rats, on the other hand, showed neither preference for olfactory stimuli from estrous females nor increase in the NAcc DA after exposure to these stimuli. These data suggest that in male LE rats olfactory stimuli from estrous females in and of themselves can be conditional cues that induce both incentive motivation and a significant increase in the NAcc DA probably as a result of being associated with sexual reward through copulatory experience. Copyright © 2017. Published by Elsevier Inc.

Influence of biophase distribution and P-glycoprotein interaction on pharmacokinetic-pharmacodynamic modelling of the effects of morphine on the EEG

PubMed Central

Groenendaal, D; Freijer, J; de Mik, D; Bouw, M R; Danhof, M; de Lange, E C M

2007-01-01

Background and purpose: The aim was to investigate the influence of biophase distribution including P-glycoprotein (Pgp) function on the pharmacokinetic-pharmacodynamic correlations of morphine's actions in rat brain. Experimental approach: Male rats received a 10-min infusion of morphine as 4 mg kg−1, combined with a continuous infusion of the Pgp inhibitor GF120918 or vehicle, 10 or 40 mg kg−1. EEG signals were recorded continuously and blood samples were collected. Key results: Profound hysteresis was observed between morphine blood concentrations and effects on the EEG. Only the termination of the EEG effect was influenced by GF120918. Biophase distribution was best described with an extended catenary biophase distribution model, with a sequential transfer and effect compartment. The rate constant for transport through the transfer compartment (k1e) was 0.038 min−1, being unaffected by GF120918. In contrast, the rate constant for the loss from the effect compartment (keo) decreased 60% after GF120918. The EEG effect was directly related to concentrations in the effect compartment using the sigmoidal Emax model. The values of the pharmacodynamic parameters E0, Emax, EC50 and Hill factor were 45.0 μV, 44.5 μV, 451 ng ml−1 and 2.3, respectively. Conclusions and implications: The effects of GF120918 on the distribution kinetics of morphine in the effect compartment were consistent with the distribution in brain extracellular fluid (ECF) as estimated by intracerebral microdialysis. However, the time-course of morphine concentrations at the site of action in the brain, as deduced from the biophase model, is distinctly different from the brain ECF concentrations. PMID:17471181

Population pharmacokinetic modelling of non-linear brain distribution of morphine: influence of active saturable influx and P-glycoprotein mediated efflux

PubMed Central

Groenendaal, D; Freijer, J; de Mik, D; Bouw, M R; Danhof, M; de Lange, E C M

2007-01-01

Background and purpose: Biophase equilibration must be considered to gain insight into the mechanisms underlying the pharmacokinetic-pharmacodynamic (PK-PD) correlations of opioids. The objective was to characterise in a quantitative manner the non-linear distribution kinetics of morphine in brain. Experimental approach: Male rats received a 10-min infusion of 4 mg kg−1 of morphine, combined with a continuous infusion of the P-glycoprotein (Pgp) inhibitor GF120918 or vehicle, or 40 mg kg−1 morphine alone. Unbound extracellular fluid (ECF) concentrations obtained by intracerebral microdialysis and total blood concentrations were analysed using a population modelling approach. Key results: Blood pharmacokinetics of morphine was best described with a three-compartment model and was not influenced by GF120918. Non-linear distribution kinetics in brain ECF was observed with increasing dose. A one compartment distribution model was developed, with separate expressions for passive diffusion, active saturable influx and active efflux by Pgp. The passive diffusion rate constant was 0.0014 min−1. The active efflux rate constant decreased from 0.0195 min−1 to 0.0113 min−1 in the presence of GF120918. The active influx was insensitive to GF120918 and had a maximum transport (Nmax/Vecf) of 0.66 ng min−1 ml−1 and was saturated at low concentrations of morphine (C50=9.9 ng ml−1). Conclusions and implications: Brain distribution of morphine is determined by three factors: limited passive diffusion; active efflux, reduced by 42% by Pgp inhibition; low capacity active uptake. This implies blood concentration-dependency and sensitivity to drug-drug interactions. These factors should be taken into account in further investigations on PK-PD correlations of morphine. PMID:17471182

Study of the interaction of 6-mercaptopurine with protein by microdialysis coupled with LC and electrochemical detection based on functionalized multi-wall carbon nanotubes modified electrode.

PubMed

Cao, Xu-Ni; Lin, Li; Zhou, Yu-Yan; Zhang, Wen; Shi, Guo-Yue; Yamamoto, Katsunobu; Jin, Li-Tong

2003-07-14

Microdialysis sampling coupled with liquid chromatography and electrochemical detection (LC-ECD) was developed and applied to study the interaction of 6-Mercaptopurine (6-MP) with bovine serum albumin (BSA). In the LC-ECD, the multi-wall carbon nanotubes fuctionalized with carboxylic groups modified electrode (MWNT-COOH CME) was used as the working electrode for the determination of 6-MP. The results indicated that this chemically modified electrode (CME) exhibited efficiently electrocatalytic oxidation for 6-MP with relatively high sensitivity, stability and long-life. The peak currents of 6-MP were linear to its concentrations ranging from 4.0 x 10(-7) to 1.0 x 10(-4) mol l(-1) with the calculated detection limit (S/N = 3) of 2.0 x 10(-7) mol l(-1). The method had been successfully applied to assess the association constant (K) and the number of the binding sites (n) on a BSA molecular, which calculated by Scatchard equation, were 3.97 x 10(3) mol(-1) l and 1.51, respectively. This method provided a fast, sensible and simple technique for the study of drug-protein interactions.

"Heart-cut" bidimensional achiral-chiral liquid chromatography applied to the evaluation of stereoselective metabolism, in vivo biological activity and brain response to chiral drug candidates targeting the central nervous system.

PubMed

Battisti, Umberto M; Citti, Cinzia; Larini, Martina; Ciccarella, Giuseppe; Stasiak, Natalia; Troisi, Luigino; Braghiroli, Daniela; Parenti, Carlo; Zoli, Michele; Cannazza, Giuseppe

2016-04-22

A "heart-cut" two-dimensional achiral-chiral liquid chromatography triple-quadrupole mass spectrometry method (LC-LC-MS/MS) was developed and coupled to in vivo cerebral microdialysis to evaluate the brain response to the chiral compound (±)-7-chloro-5-(3-furanyl)-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxide ((±)-1), a potent positive allosteric modulator (PAM) of AMPA receptor. The method was successfully employed to evaluate also its stereoselective metabolism and in vitro biological activity. In particular, the LC achiral method developed, employs a pentafluorinated silica based column (Discovery HS-F5) to separate dopamine, acetylcholine, serotonin, (±)-1 and its two hepatic metabolites. In the "heart-cut" two-dimension achiral-chiral configuration, (±)-1 and (±)-1-d4 eluted from the achiral column (1st dimension), were transferred to a polysaccharide-based chiral column (2nd dimension, Chiralcel OD-RH) by using an automatic six-port valve. Single enantiomers of (±)-1 were separated and detected using electrospray positive ionization mode and quantified in selected reaction monitoring mode. The method was validated and showed good performance in terms of linearity, accuracy and precision. The new method employed showed several possible applications in the evaluation of: (a) brain response to neuroactive compounds by measuring variations in the brain extracellular levels of selected neurotransmitters and other biomarkers; (b) blood brain barrier penetration of drug candidates by measuring the free concentration of the drug in selected brain areas; (c) the presence of drug metabolites in the brain extracellular fluid that could prove very useful during drug discovery; (d) a possible stereoselective metabolization or blood brain barrier stereoselective crossing of chiral drugs. Finally, compared to the methods reported in the literature, this technique avoids the necessity of euthanizing an animal at each time point to measure drug concentration in whole brain tissue and provides continuous monitoring of extracellular concentrations of single chiral drug enantiomers along with its metabolites in specific brain regions at each selected time point for a desired period by using a single animal. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantification of Phenol, Phenyl Glucuronide, and Phenyl Sulfate in Blood of Unanesthetized Rainbow Trout by On-line Microdialysis Sampling

EPA Science Inventory

In this study we have developed a novel method to estimate in vivo rates of metabolism in unanesthetized fish. This method provides a basis for evaluating the accuracy of in vitro-in vivo metabolism extrapolations. As such, this research will lead to improved risk assessments f...

Effect of acute administration of hypericum perforatum-CO2 extract on dopamine and serotonin release in the rat central nervous system.

PubMed

Di Matteo, V; Di Giovanni, G; Di Mascio, M; Esposito, E

2000-01-01

The hydromethanolic extract of Hypericum perforatum has been shown to be an effective antidepressant, although its mechanism of action is still unclear. In this study, in vivo microdialysis was used to investigate the effects of Hypericum perforatum-CO2 extract on dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) release in various areas of brain. Administration of Hypericum perforatum extract (1 mg/kg, p.o.) caused a slight, but significant increase of DA outflow both in the nucleus accumbens and the striatum. The maximal increase of DA efflux (+19.22+/-1.93%, relative to the control group) in the nucleus accumbens occurred 100 min after administration of Hypericum perforatum. In the striatum, the extract maximally enhanced DA outflow (+24.83+/-7.49 %, relative to the control group) 80 min after administration. Extraneuronal DOPAC levels were not significantly affected by Hypericum perforatum treatment. Moreover, Hypericum perforatum (1 mg/kg, p.o.) did not produce any significant effect on either 5-HT or 5-HIAA efflux in the ventral hippocampus. This study shows for the first time that Hypericum perforatum extract is capable of increasing in vivo DA release.

Intranasal administration of oxytocin: behavioral and clinical effects, a review.

PubMed

Veening, Jan G; Olivier, Berend

2013-09-01

The intranasal (IN-) administration of substances is attracting attention from scientists as well as pharmaceutical companies. The effects are surprisingly fast and specific. The present review explores our current knowledge about the routes of access to the cranial cavity. 'Direct-access-pathways' from the nasal cavity have been described but many additional experiments are needed to answer a variety of open questions regarding anatomy and physiology. Among the IN-applied substances oxytocin (OT) has an extensive history. Originally applied in women for its physiological effects related to lactation and parturition, over the last decade most studies focused on their behavioral 'prosocial' effects: from social relations and 'trust' to treatment of 'autism'. Only very recently in a microdialysis study in rats and mice, the 'direct-nose-brain-pathways' of IN-OT have been investigated directly, implying that we are strongly dependent on results obtained from other IN-applied substances. Especially the possibility that IN-OT activates the 'intrinsic' OT-system in the hypothalamus as well needs further clarification. We conclude that IN-OT administration may be a promising approach to influence human communication but that the existing lack of information about the neural and physiological mechanisms involved is a serious problem for the proper understanding and interpretation of the observed effects. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sleep duration varies as a function of glutamate and GABA in rat pontine reticular formation.

PubMed

Watson, Christopher J; Lydic, Ralph; Baghdoyan, Helen A

2011-08-01

The oral part of the pontine reticular formation (PnO) is a component of the ascending reticular activating system and plays a role in the regulation of sleep and wakefulness. The PnO receives glutamatergic and GABAergic projections from many brain regions that regulate behavioral state. Indirect, pharmacological evidence has suggested that glutamatergic and GABAergic signaling within the PnO alters traits that characterize wakefulness and sleep. No previous studies have simultaneously measured endogenous glutamate and GABA from rat PnO in relation to sleep and wakefulness. The present study utilized in vivo microdialysis coupled on-line to capillary electrophoresis with laser-induced fluorescence to test the hypothesis that concentrations of glutamate and GABA in the PnO vary across the sleep/wake cycle. Concentrations of glutamate and GABA were significantly higher during wakefulness than during non-rapid eye movement sleep and rapid eye movement sleep. Regression analysis revealed that decreases in glutamate and GABA accounted for a significant portion of the variance in the duration of non-rapid eye movement sleep and rapid eye movement sleep episodes. These data provide novel support for the hypothesis that endogenous glutamate and GABA in the PnO contribute to the regulation of sleep duration. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

Microdialysis measurements of lamellar perfusion and energy metabolism during the development of laminitis in the oligofructose model.

PubMed

Medina-Torres, C E; Underwood, C; Pollitt, C C; Castro-Olivera, E M; Hodson, M P; Richardson, D W; van Eps, A W

2016-03-01

Failure of lamellar energy metabolism, with or without ischaemia, may be important in the pathophysiology of sepsis-associated laminitis. To examine lamellar perfusion and energy balance during laminitis development in the oligofructose model using tissue microdialysis. In vivo experiment. Six Standardbred horses underwent laminitis induction using the oligofructose model (OFT group) and 6 horses were untreated controls (CON group). Microdialysis probes were placed in the lamellar tissue of one forelimb (all horses) as well as the skin dermis of the tail in OFT horses. Dialysate and plasma samples were collected every 2 h for 24 h and concentrations of energy metabolites (glucose, lactate, pyruvate) and standard indices of energy metabolism (lactate to glucose ratio [L:G] and lactate to pyruvate ratio [L:P]) determined. Microdialysis urea clearance was used to estimate changes in tissue perfusion. Data were analysed nonparametrically. Median glucose concentration decreased to <30% of baseline by 8 h in OFT lamellar (P = <0.01) and skin (P<0.01) dialysate. Lactate increased mildly in skin dialysate (P = 0.04) and plasma (P = 0.05) but not lamellar dialysate in OFT horses. Median pyruvate concentration decreased to <50% of baseline in OFT lamellar dialysate (P = 0.03). A >5-fold increase in median L:G compared with baseline occurred in OFT lamellar and skin dialysate (P<0.03). From a baseline of <20, median L:P increased to a peak of 80 in OFT skin and 38.7 in OFT lamellar dialysates (P<0.02); however, OFT lamellar dialysate L:P was not significantly different from CON. Urea concentration decreased significantly in OFT lamellar dialysate (increased urea clearance) but not in OFT skin or CON lamellar dialysate. Increased lamellar perfusion occurred during the development of sepsis-associated laminitis in the oligofructose model. Glucose concentrations in the lamellar interstitium decreased, suggesting increased glucose consumption but there was no definitive evidence of lamellar energy failure. © 2015 EVJ Ltd.

Increased adipose tissue lipolysis after a 2-week high-fat diet in sedentary overweight/obese men.

PubMed

Howe, Harold R; Heidal, Kimberly; Choi, Myung Dong; Kraus, Ray M; Boyle, Kristen; Hickner, Robert C

2011-07-01

The purpose of this study was to determine if a high-fat diet would result in a higher lipolytic rate in subcutaneous adipose tissue than a lower-fat diet in sedentary nonlean men. Six participants (healthy males; 18-40 years old; body mass index, 25-37 kg/m(2)) underwent 2 weeks on a high-fat or well-balanced diet of similar energy content (approximately 6695 kJ) in randomized order with a 10-day washout period between diets. Subcutaneous abdominal adipose tissue lipolysis was determined over the course of a day using microdialysis after both 2-week diet sessions. Average interstitial glycerol concentrations (index of lipolysis) as determined using microdialysis were higher after the high-fat diet (210.8 ± 27.9 μmol/L) than after a well-balanced diet (175.6 ± 23.3 μmol/L; P = .026). There was no difference in adipose tissue microvascular blood flow as determined using the microdialysis ethanol technique. These results demonstrate that healthy nonlean men who diet on the high-fat plan have a higher lipolytic rate in subcutaneous abdominal adipose tissue than when they diet on a well-balanced diet plan. This higher rate of lipolysis may result in a higher rate of fat mass loss on the high-fat diet; however, it remains to be determined if this higher lipolytic rate in men on the high-fat diet results in a more rapid net loss of triglyceride from the abdominal adipose depots, or if the higher lipolytic rate is counteracted by an increased rate of lipid storage. Copyright © 2011 Elsevier Inc. All rights reserved.

Increased adipose tissue lipolysis after a two-week high-fat diet in sedentary overweight/obese men

PubMed Central

Howe, Harold R; Heidal, Kimberly; Choi, Myung Dong; Kraus, Ray M.; Boyle, Kristen; Hickner, Robert C.

2013-01-01

Background/Objectives The purpose of this study was to determine if a high fat diet would result in a higher lipolytic rate in subcutaneous adipose tissue than a lower fat diet in sedentary non-lean men. Subjects/Methods Six participants (healthy males: 18-40 yrs old: body mass index 25-37 kg/m2) underwent two weeks on a high-fat or well-balanced diet of similar caloric content (approx. 1600 kcal) in randomized order with a ten-day washout period between diets. Subcutaneous abdominal adipose tissue lipolysis was determined over the course of a day using microdialysis after both two-week diet sessions. Results Average interstitial glycerol concentrations (index of lipolysis) as determined using microdialysis were higher following the high-fat diet (210.8 ±27.9 μM) than following a well-balanced diet (175.6 ± 23.3 μM; P = 0.026). There was no difference in adipose tissue microvascular blood flow as determined using the microdialysis ethanol technique. Conclusions These results demonstrate that healthy non-lean men who diet on the high-fat plan have a higher lipolytic rate in subcutaneous abdominal adipose tissue than when they diet on a well-balanced diet plan. This higher rate of lipolysis may result in a higher rate of fat mass loss on the high-fat diet; however, it remains to be determined if this higher lipolytic rate in men on the high-fat diet results in a more rapid net loss of triglyceride from the abdominal adipose depots, or if the higher lipolytic rate is counteracted by an increased rate of lipid storage. PMID:21040937

Muscle oxygenation and glycolysis in females with trapezius myalgia during stress and repetitive work using microdialysis and NIRS.

PubMed

Sjøgaard, Gisela; Rosendal, Lars; Kristiansen, Jesper; Blangsted, Anne K; Skotte, Jørgen; Larsson, Britt; Gerdle, Björn; Saltin, Bengt; Søgaard, Karen

2010-03-01

The aim of this investigation was to study female workers active in the labour market for differences between those with trapezius myalgia (MYA) and without (CON) during repetitive pegboard (PEG) and stress (STR) tasks regarding (1) relative muscle load, (2) trapezius muscle blood flow, (3) metabolite accumulation, (4) oxygenation, and (5) pain development. Among 812 female employees (age 30-60 years) at 7 companies with high prevalence of neck/shoulder complaints, clinical examination identified 43 MYA and 19 CON. At rest, during PEG, and STR the trapezius muscle was measured using (1) EMG and MMG, (2) microdialysis, and (3) NIRS. Further, subjective pain ratings were scored (VAS). EMGrms in %MVE (Maximal Voluntary EMG-activity), was significantly higher among MYA than CON during PEG (11.74 +/- 9.09 vs. 7.42 +/- 5.56%MVE) and STR (5.47 +/- 5.00 vs. 3.28 +/- 1.94%MVE). MANOVA showed a group and time effect regarding data from the microdialysis: for MYA versus CON group differences demonstrated lower muscle blood flow and higher lactate and pyruvate concentrations. Potassium and glucose only showed time effects. NIRS showed similar initial decreases in oxygenation with PEG in both groups, but only in CON a significant increase back to baseline during PEG. VAS score at rest was highest among MYA and increased during PEG, but not for CON. The results showed significant differences between CON and MYA regarding muscle metabolism at rest and with PEG and STR. Higher relative muscle load during PEG and STR, insufficient muscle blood flow and oxygenation may account for the higher lactate, pyruvate and pain responses among MYA versus CON.

Prefrontal cortical network activity: Opposite effects of psychedelic hallucinogens and D1/D5 dopamine receptor activation

PubMed Central

Lambe, Evelyn K.; Aghajanian, George K.

2007-01-01

The fine-tuning of network activity provides a modulating influence on how information is processed and interpreted in the brain. Here, we use brain slices of rat prefrontal cortex to study how recurrent network activity is affected by neuromodulators known to alter normal cortical function. We previously determined that glutamate spillover and stimulation of extrasynaptic NMDA receptors are required to support hallucinogen-induced cortical network activity. Since microdialysis studies suggest that psychedelic hallucinogens and dopamine D1/D5 receptor agonists have opposite effects on extracellular glutamate in prefrontal cortex, we hypothesized that these two families of psychoactive drugs would have opposite effects on cortical network activity. We found that network activity can be enhanced by DOI (a psychedelic hallucinogen that is a partial agonist of serotonin 5-HT2A/2C receptors) and suppressed by the selective D1/D5 agonist SKF 38393. This suppression could be mimicked by direct activation of adenylyl cyclase with forskolin or by addition of a cAMP analog. These findings are consistent with previous work showing that activation of adenylyl cyclase can upregulate neuronal glutamate transporters, thereby decreasing synaptic spillover of glutamate. Consistent with this hypothesis, a low concentration of the glutamate transporter inhibitor TBOA restored electrically-evoked recurrent activity in the presence of a selective D1/D5 agonist, whereas recurrent activity in the presence of a low level of the GABAA antagonist bicuculline was not resistant to suppression by the D1/D5 agonist. The tempering of network UP states by D1/D5 receptor activation may have implications for the proposed use of D1/D5 agonists in the treatment of schizophrenia. PMID:17293055

Strain differences in basal and post-citalopram extracellular 5-HT in the mouse medial prefrontal cortex and dorsal hippocampus: relation with tryptophan hydroxylase-2 activity.

PubMed

Calcagno, E; Canetta, A; Guzzetti, S; Cervo, L; Invernizzi, R W

2007-11-01

We used the microdialysis technique to compare basal extracellular serotonin (5-HT) and the response to citalopram in different strains of mice with functionally different allelic forms of tryptophan hydroxylase-2 (TPH-2), the rate-limiting enzyme in brain 5-HT synthesis. DBA/2J, DBA/2N and BALB/c mice carrying the 1473G allele of TPH-2 had less dialysate 5-HT in the medial prefrontal cortex and dorsal hippocampus (DH) (20-40% reduction) than C57BL/6J and C57BL/6N mice carrying the 1473C allele. Extracellular 5-HT estimated by the zero-net flux method confirmed the result of conventional microdialysis. Citalopram, 1.25, 5 and 20 mg/kg, dose-dependently raised extracellular 5-HT in the medial prefrontal cortex of C57BL/6J mice, with maximum effect at 5 mg/kg, but had significantly less effect in DBA/2J and BALB/c mice and in the DH of DBA/2J mice. A tryptophan (TRP) load enhanced basal extracellular 5-HT in the medial prefrontal cortex of DBA/2J mice but did not affect citalopram's ability to raise cortical and hippocampal extracellular 5-HT. The impairment of 5-HT synthesis quite likely accounts for the reduction of basal 5-HT and the citalopram-induced rise in mice carrying the mutated enzyme. These findings might explain why DBA/2 and BALB/c mice do not respond to citalopram in the forced swimming test. Although TRP could be a useful strategy to improve the antidepressant effect of citalopram (Cervo et al. 2005), particularly in subjects with low 5-HT synthesis, the contribution of serotonergic and non-serotonergic mechanisms to TRP's effect remains to be elucidated.

Involvement of 5-HT3 receptors in the action of vortioxetine in rat brain: Focus on glutamatergic and GABAergic neurotransmission.

PubMed

Riga, Maurizio S; Sánchez, Connie; Celada, Pau; Artigas, Francesc

2016-09-01

The antidepressant vortioxetine is a 5-HT3-R, 5-HT7-R and 5-HT1D-R antagonist, 5-HT1B-R partial agonist, 5-HT1A-R agonist, and serotonin (5-HT) transporter (SERT) inhibitor. Vortioxetine occupies all targets at high therapeutic doses and only SERT and 5-HT3-R at low doses. Vortioxetine increases extracellular monoamine concentrations in rat forebrain more than selective serotonin reuptake inhibitors (SSRI) and shows pro-cognitive activity in preclinical models. Given its high affinity for 5-HT3-R (Ki = 3.7 nM), selectively expressed in GABA interneurons, we hypothesized that vortioxetine may disinhibit glutamatergic and monoaminergic neurotransmission following 5-HT3-R blockade. Here we assessed vortioxetine effect on pyramidal neuron activity and extracellular 5-HT concentration using in vivo extracellular recordings of rat medial prefrontal cortex (mPFC) pyramidal neurons and microdialysis in mPFC and ventral hippocampus (vHPC). Vortioxetine, but not escitalopram, increased pyramidal neuron discharge in mPFC. This effect was prevented by SR57227A (5-HT3-R agonist) and was mimicked by ondansetron (5-HT3-R antagonist) and by escitalopram/ondansetron combinations. In microdialysis experiments, ondansetron augmented the 5-HT-enhancing effect of escitalopram in mPFC and vHPC. Local ondansetron in vHPC augmented escitalopram effect, indicating the participation of intrinsic mechanisms. Since 5-HT neurons express GABAB receptors, we examined their putative involvement in controlling 5-HT release after 5-HT3-R blockade. Co-perfusion of baclofen (but not muscimol) reversed the increased 5-HT levels produced by vortioxetine and escitalopram/ondansetron combinations in vHPC. The present results suggest that vortioxetine increases glutamatergic and serotonergic neurotransmission in rat forebrain by blocking 5-HT3 receptors in GABA interneurons. Copyright © 2016. Published by Elsevier Ltd.

Triple electrical channels on a triple fluid swivel and its use to monitor intracranial temperature with a thermocouple.

PubMed

Parada, M A; Puig de Parada, M; Hernandez, L; Hoebel, B G

1995-08-01

A low-torque, bubble-free and multiple-channel fluid swivel of easy construction was recently described. This paper describes the design, construction and testing of 3 electrical channels added to the original fluid swivel. The new channels were tested monitoring intrahypothalamic temperature (T(hy)) by means of a copper-constantan thermocouple in freely moving rats, before and after a single intraperitoneal (i.p.) amphetamine injection (3 mg/kg). This test showed an increase in T(hy) after the injection and the maintenance of the electrical continuity along the whole testing period, even when the animals were hyperactive. With this improvement the original swivel was transformed in a more versatile device for experiments requiring fluid handlings and electrophysiological manipulations. Electrical stimulation as in kindling or brain self-stimulation, and electrophysiological recordings as in electroencephalography, electromiography, electrocardiography, in vivo voltammetry and even neuronal unit recording, are just examples of the electrophysiological methods that can be combined with drug self-administration and microdialysis using the present device.

[Mediolateral gradient of the nucleus accumbens nitrergic activation during exploratory behavior].

PubMed

Saul'skaia, N B; Sudorgina, P V

2012-04-01

In Sprague-Dawley rats, by means of in vivo microdialysis combined with HPLC analysis it has been shown that an exploratory behavior in a new environment is accompanied by a rise in extracellular levels of citrulline (an NO co-product) in the mediolateral regions of the n. accumbens with the maximum observed in the medial n. accumbens. Infusions of 7-nitroindazole (0.5 mM), a neuronal NO synthase inhibitor, into the medial n. accumbens prevented the exploration-induced rise of extracellular citrulline levels in this area. The second presentation of the same chamber did not produce any significant changes of extracellular citrulline levels in the medial n. accumbens, although there was a tendency of a small increase. The presentation of a familiar chamber did not affect citrulline extracellular levels in this area. The data obtained indicate for the first time that exploratory activity in a new environment is accompanied by the nitrergic activation in the entire n. accumbens with the maximal activation in the medial part of this brain area.

New method for monitoring nitric oxide in vivo using microdialysis sampling and chemiluminescence reaction

NASA Astrophysics Data System (ADS)

Yao, Dachun; Evmiridis, Nick P.; Zhou, Yikai; Xu, Shunqing; Zhou, Huarong

2001-09-01

A new method employing a combination of micro dialysis sampling and chemiluminescence reaction was developed to monitor nitric oxide (NO) in vivo. A special probe was designed with an interference-free membrane to achieve a very high selectivity for NO. High sensitivity was achieved by optimizing the working system and improving the NO sampling time. This system was used in vivo to monitor blood and brain tissue in rats and rabbits. We have established that this system is sensitive enough to detect variations in NO production in difference physiological state. The system can detect NO in the linear range of 5nM-1(mu) M, with a detection limit of 1nM, and real NO concentrations in our experimental animals were found to be in the range of 1-5 nM or even less. Finally, the effects of body temperature, NO donors, Viagra, NO activators, NO cofactors, NO interference were investigated carefully in different physiological situations.

Mechanisms and time course of menthol-induced cutaneous vasodilation

PubMed Central

Craighead, Daniel H.; McCartney, Nathaniel B.; Tumlinson, James H.; Alexander, Lacy M.

2017-01-01

Menthol is a vasoactive compound that is widely used in topical analgesic agents. Menthol induces cutaneous vasodilation, however the underlying mechanisms are unknown. Determining the rates of appearance and clearance of menthol in the skin is important for optimizing topical treatment formulation and dosing. The purpose of this study was to determine the mechanisms contributing to menthol-mediated cutaneous vasodilation and to establish a time course for menthol appearance/clearance in the skin. Ten young (23±1 years, 5 males 5 females) subjects participated in two protocols. In study 1, four intradermal microdialysis fibers were perfused with increasing doses of menthol (0.1-500mM) and inhibitors for nitric oxide (NO), endothelium derived hyperpolarizing factors (EDHFs), and sensory nerves. Skin blood flow was measured with laser Doppler flowmetry and normalized to %CVCmax. In study 2, two intradermal microdialysis fibers were perfused with lactated Ringer's solution. 0.017mL•cm-2 of a 4% menthol gel was placed over each fiber. 5μL samples of dialysate from the microdialysis fibers were collected every 30 minutes and analyzed for the presence of menthol with high performance gas chromatography/mass spectrometry. Skin blood flow (laser speckle contrast imaging) and subjective ratings of menthol sensation were simultaneously obtained with dialysate samples. In study 1, menthol induced cutaneous vasodilation at all doses ≥100mM (all p<0.05). However, inhibition of either NO, EDHFs, or sensory nerves fully inhibited menthol-mediated vasodilation (all p>0.05). In study 2, significant menthol was detected in dialysate 30 minutes post menthol application (0.89ng, p=0.0002). Relative to baseline, cutaneous vasodilation was elevated from minutes 15-45 and ratings of menthol sensation were elevated from minute 5-60 post menthol application (all p<0.05). Menthol induces cutaneous vasodilation in the skin through multiple vasodilator pathways, including NO, EDHF, and sensory nerves. Topical menthol is detectable in the skin within 30 minutes and is cleared by 60 minutes. Skin blood flow and perceptual measures follow a similar time course as menthol appearance/clearance. PMID:27899298

Modulation of basal and stress-induced amygdaloid substance P release by the potent and selective NK1 receptor antagonist L-822429.

PubMed

Singewald, Nicolas; Chicchi, Gary G; Thurner, Clemens C; Tsao, Kwei-Lan; Spetea, Mariana; Schmidhammer, Helmut; Sreepathi, Hari Kishore; Ferraguti, Francesco; Singewald, Georg M; Ebner, Karl

2008-09-01

It has been shown that anxiety and stress responses are modulated by substance P (SP) released within the amygdala. However, there is an important gap in our knowledge concerning the mechanisms regulating extracellular SP in this brain region. To study a possible self-regulating role of SP, we used a selective neurokinin-1 (NK1) receptor antagonist to investigate whether blockade of NK1 receptors results in altered basal and/or stress-evoked SP release in the medial amygdala (MeA), a critical brain area for a functional involvement of SP transmission in enhanced anxiety responses induced by stressor exposure. In vitro binding and functional receptor assays revealed that L-822429 represents a potent and selective rat NK1 receptor antagonist. Intra-amygdaloid administration of L-822429 via inverse microdialysis enhanced basal, but attenuated swim stress-induced SP release, while the low-affinity enantiomer of L-822429 had no effect. Using light and electron microscopy, synaptic contacts between SP-containing fibres and dendrites expressing NK1 receptors was demonstrated in the medial amygdala. Our findings suggest self-regulatory capacity of SP-mediated neurotransmission that differs in the effect on basal and stress-induced release of SP. Under basal conditions endogenous SP can serve as a signal that tonically inhibits its own release via a NK1 receptor-mediated negative feedback action, while under stress conditions SP release is further facilitated by activation of NK1 receptors, likely leading to high local levels of SP and activation of receptors to which SP binds with lower affinity.

Oxytocin-induced yawning: sites of action in the brain and interaction with mesolimbic/mesocortical and incertohypothalamic dopaminergic neurons in male rats.

PubMed

Sanna, Fabrizio; Argiolas, Antonio; Melis, Maria Rosaria

2012-09-01

Oxytocin (80 ng) induces yawning when injected into the caudal part of the ventral tegmental area, the hippocampal ventral subiculum and the posteromedial nucleus of the amygdala of male rats. The behavioural response occurred concomitantly with an increase in the concentration of extracellular dopamine and its main metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the dialysate obtained from the shell of the nucleus accumbens and of the prelimbic medial prefrontal cortex by means of intracerebral microdialysis. Both oxytocin responses were significantly reduced by d(CH₂)₅Tyr(Me)²-Orn⁸-vasotocin, a selective oxytocin receptor antagonist, injected in the above brain areas 15 min before oxytocin. Similar results were obtained by activating central oxytocinergic neurons originating in the paraventricular nucleus of the hypothalamus and projecting to the ventral tegmental area, the hippocampus and the amygdala, with the dopamine agonist apomorphine given at a dose that induces yawning when injected into the paraventricular nucleus. Since oxytocin is considered a key regulator of emotional and social reward that enhances amygdala-dependent, socially reinforced learning and emotional empathy, mesolimbic and mesocortical dopamine neurons play a key role in motivation and reward, and yawning in mammals is considered a primitive, unconscious form of empathy, the present results support the hypothesis that oxytocinergic neurons originating in the paraventricular nucleus of the hypothalamus and projecting to the above brain areas and mesolimbic and mesocortical dopaminergic neurons participate in the complex neural circuits that play a role in the above mentioned functions. Copyright © 2012 Elsevier Inc. All rights reserved.

Cannabinoids reduce cAMP levels in the striatum of freely moving rats: an in vivo microdialysis study.

PubMed

Wade, Mark R; Tzavara, Eleni T; Nomikos, George G

2004-04-16

The cannabinoid receptor subtype 1 (CB1R) is a member of the G(i)-protein-coupled receptor family and cannabinoid signaling is largely dependent on the suppression of adenylyl cyclase-catalyzed cAMP production. In cell lines transfected with the CB1R or in native tissue preparations, treatment with cannabinoid agonists reduces both basal and forskolin-stimulated cAMP synthesis. We measured extracellular cAMP concentrations in the striatum of freely moving rats utilizing microdialysis to determine if changes in cAMP concentrations in response to CB1R agonists can be monitored in vivo. Striatal infusion of the CB1R agonist WIN55,212-2 (100 microM or 1 mM), dose-dependently decreased basal and forskolin-stimulated extracellular cAMP. These effects were reversed by co-infusion of the CB1R antagonist SR141716A (30 microM), which alone had no effect up to the highest concentration tested (300 microM). These data indicate that changes in extracellular cAMP concentrations in response to CB1R stimulation can be monitored in vivo allowing the study of cannabinoid signaling in the whole animal.

Simultaneous Determination of Oleanolic Acid and Ursolic Acid by in Vivo Microdialysis via UHPLC-MS/MS Using Magnetic Dispersive Solid Phase Extraction Coupling with Microwave-Assisted Derivatization and Its Application to a Pharmacokinetic Study of Arctiumlappa L. Root Extract in Rats.

PubMed

Zheng, Zhenjia; Zhao, Xian-En; Zhu, Shuyun; Dang, Jun; Qiao, Xuguang; Qiu, Zhichang; Tao, Yanduo

2018-04-18

Simultaneous detection of oleanolic acid and ursolic acid in rat blood by in vivo microdialysis can provide important pharmacokinetics information. Microwave-assisted derivatization coupled with magnetic dispersive solid phase extraction was established for the determination of oleanolic acid and ursolic acid by liquid chromatography tandem mass spectrometry. 2'-Carbonyl-piperazine rhodamine B was first designed and synthesized as the derivatization reagent, which was easily adsorbed onto the surface of Fe 3 O 4 /graphene oxide. Simultaneous derivatization and extraction of oleanolic acid and ursolic acid were performed on Fe 3 O 4 /graphene oxide. The permanent positive charge of the derivatization reagent significantly improved the ionization efficiencies. The limits of detection were 0.025 and 0.020 ng/mL for oleanolic acid and ursolic acid, respectively. The validated method was shown to be promising for sensitive, accurate, and simultaneous determination of oleanolic acid and ursolic acid. It was used for their pharmacokinetics study in rat blood after oral administration of Arctiumlappa L. root extract.

Drug pharmacokinetics and pharmacodynamics: PET and microdial studies of SR 46349B, a selective 5HT2 antagonist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, P.; Dewey, S.L.; Gatley, S.J.

1994-05-01

The brain serotonin system is an important molecular target in drug development. SR 46349B is a propenone oxime ether derivative with a high affinity and selectivity for the serotonin 5HT2 receptor (Kd=1.2 nM). We have labeled SR 46349B with carbon-11 via N-methylation of a nor-precursor (supplied by Sanofi Recherche) with C-11 methyl iodide. Purification by HPLC gave [11C]SR 46349B in 98% radiochemical purity with a specific activity of 1.5 Ci/{mu}mol. Serial PET studies were carried out in a baboon for a 60 minute study period with a two hour time interval between studies. The first study was at baseline andmore » the second after pretreatment with altanserin (0.5 mg/kg iv, 30 min prior to [11C]SR 46349B). Carbon-11 peaked at ca. 20 minutes in the frontal, parietal, temporal and occipital cortices where it plateaued for the rest of the study. Cerebellum, thalamus and striatum peaked at ca. 10 minutes and cleared to 62%, 72% and 80% of peak by 60 min. At 60 minutes, the frontal cortex to cerebellum ratio was 1.5. Treatment with altanserin reduced the frontal cortex to cerebellum ratio to 1.0. HPLC of mouse brain homogenate after [11C]SR 46349B showed >94% of the C-11 was parent compound. Microdialysis in freely moving rats after injection of SR 46349B (n=6; 10 mg/kg, ip) showed an average peak increase in extracellular dopamine of 375% which is higher than the 150% effect of altanserin. Spontaneous movements were markedly reduced. The pharmacokinetics of [11C] SR 46349B in cortical areas is consistent with the long term effects of SR 46349B on 5HT2 receptors and the elevations in extracellular dopamine without increased locomotor activity are consistent with serotonin mediated disinhibition of striatal dopamine release via blockade of serotonin receptors.« less

Effects of aniracetam on extracellular levels of transmitter amino acids in the hippocampus of the conscious gerbils: an intracranial microdialysis study.

PubMed

Yu, Siming; Cai, Jingxia

2003-03-27

The effects of aniracetam on extracellular amino acid levels in the hippocampus of conscious gerbils, with or without transient cerebral ischemia/reperfusion, were measured by microdialysis and reverse phase-high performance liquid chromatography. Increased extracellular levels of aspartate and glutamate that were observed in the hippocampus of conscious gerbils during transient global forebrain ischemia were reversed by aniracetam. In contrast, the level of extracellular gamma-aminobutyric acid was increased, while taurine was maintained at a higher level than other amino acids by administration of aniracetam (100 mg/kg, p.o.) 60 min before ischemia. Further, in contrast to ischemic animals, administration of aniracetam (100 mg/kg, p.o.) enhanced the release of glutamate and aspartate in the normal gerbil hippocampus. The results suggest that these effects might be due to a partial calcium agonist activity of aniracetam, and that the effects of aniracetam on amino acid levels might be a mechanism of protection against delayed neuronal death in the ischemic hippocampus, thereby improving memory dysfunction induced by ischemia/reperfusion.

Extracellular levels of amino acids and choline in human high grade gliomas: an intraoperative microdialysis study.

PubMed

Bianchi, L; De Micheli, E; Bricolo, A; Ballini, C; Fattori, M; Venturi, C; Pedata, F; Tipton, K F; Della Corte, L

2004-01-01

The concentrations of endogenous amino acids and choline in the extracellular fluid of human cerebral gliomas have been measured, for the first time, by in vivo microdialysis. Glioblastoma growth was associated with increased concentrations of choline, GABA, isoleucine, leucine, lysine, phenylalanine, taurine, tyrosine, and valine. There was no difference between grade III and grade IV tumors in the concentrations of phenylalanine, isoleucine, tyrosine, valine, and lysine, whereas the concentrations of choline, aspartate, taurine, GABA, leucine, and glutamate were significantly different in the two tumor-grade subgroups. In contrast to the other compounds, the concentration of glutamate was decreased in glioma. The parenchyma adjacent to the tumor showed significant changes only in the extracellular concentration of glutamate, isoleucine, and valine. The concentrations of choline and the amino acids, glutamate, leucine, taurine, and tyrosine showed significant positive correlations with the degree of cell proliferation. Epilepsy, which is relatively common in subjects with gliomas, was shown to be a significant confounding variable when the extracellular concentrations of aspartate, glutamate and GABA were considered.

Tph2 gene deletion enhances amphetamine-induced hypermotility: effect of 5-HT restoration and role of striatal noradrenaline release.

PubMed

Carli, Mirjana; Kostoula, Chrysaugi; Sacchetti, Giuseppina; Mainolfi, Pierangela; Anastasia, Alessia; Villani, Claudia; Invernizzi, Roberto William

2015-11-01

Variants of tryptophan hydroxylase-2 (Tph2), the gene encoding enzyme responsible for the synthesis of brain serotonin (5-HT), have been associated with neuropsychiatric disorders, substance abuse and addiction. This study assessed the effect of Tph2 gene deletion on motor behavior and found that motor activity induced by 2.5 and 5 mg/kg amphetamine was enhanced in Tph2(-/-) mice. Using the in vivo microdialysis technique we found that the ability of amphetamine to stimulate noradrenaline (NA) release in the striatum was reduced by about 50% in Tph2(-/-) mice while the release of dopamine (DA) was not affected. Tph2 deletion did not affect the release of NA and DA in the prefrontal cortex. The role of endogenous 5-HT in enhancing the effect of amphetamine was confirmed showing that treatment with the 5-HT precursor 5-hydroxytryptophan (10 mg/kg) restored tissue and extracellular levels of brain 5-HT and the effects of amphetamine on striatal NA release and motor activity in Tph2(-/-) mice. Treatment with the NA precursor dihydroxyphenylserine (400 mg/kg) was sufficient to restore the effect of amphetamine on striatal NA release and motor activity in Tph2(-/-) mice. These findings indicate that amphetamine-induced hyperactivity is attenuated by endogenous 5-HT through the inhibition of striatal NA release. Tph2(-/-) mice may be a useful preclinical model to assess the role of 5-HT-dependent mechanisms in the action of psychostimulants. Acute sensitivity to the motor effects of amphetamine has been associated to increased risk of psychostimulant abuse. Here, we show that deletion of Tph2, the gene responsible for brain 5-HT synthesis, enhances the motor effect of amphetamine in mice through the inhibition of striatal NA release. This suggests that Tph2(-/-) mice is a useful preclinical model to assess the role of 5-HT-dependent mechanisms in psychostimulants action. Tph2, tryptophan hydroxylase-2. © 2015 International Society for Neurochemistry.

Development of an On-animal Separation-based Sensor for Monitoring Drug Metabolism in Freely Roaming Sheep

PubMed Central

Scott, David E.; Willis, Sean D.; Gabbert, Seth; Johnson, Dave A.; Naylor, Erik; Janle, Elsa M.; Krichevsky, Janice E.; Lunte, Craig E.; Lunte, Susan M.

2015-01-01

The development of an on-animal separation-based sensor that can be employed for monitoring drug metabolism in a freely roaming sheep is described. The system consists of microdialysis sampling coupled directly to microchip electrophoresis with electrochemical detection (MD-ME-EC). Separations were accomplished using an all-glass chip with integrated platinum working and reference electrodes. Discrete samples from the microdialysis flow were introduced into the electrophoresis chip using a flow-gated injection approach. Electrochemical detection was accomplished in-channel using a two-electrode isolated potentiostat. Nitrite was separated by microchip electrophoresis using reverse polarity and a run buffer consisting of 50 mM phosphate at pH 7.4. The entire system was under telemetry control. The system was first tested with rats to monitor the production of nitrite following introduction of nitroglycerin into the subdermal tissue using a linear probe. The data acquired using the on-line MD-ME-EC system was compared to that obtained off-line analysis by liquid chromatography with electrochemical detection (LC-EC), using a second microdialysis probe implanted parallel to the first probe in the same animal. The MD-ME-EC device was then used on-animal to monitor the subdermal metabolism of nitroglycerin in sheep. The ultimate goal is to use this device to simultaneously monitor drug metabolism and behavior in a freely roaming animal. PMID:25697221

Bedside diagnosis of mitochondrial dysfunction after malignant middle cerebral artery infarction.

PubMed

Nielsen, T H; Schalén, W; Ståhl, N; Toft, P; Reinstrup, P; Nordström, C H

2014-08-01

The study explores whether the cerebral biochemical pattern in patients treated with hemicraniectomy after large middle cerebral artery infarcts reflects ongoing ischemia or non-ischemic mitochondrial dysfunction. The study includes 44 patients treated with decompressive hemicraniectomy (DCH) due to malignant middle cerebral artery infarctions. Chemical variables related to energy metabolism obtained by microdialysis were analyzed in the infarcted tissue and in the contralateral hemisphere from the time of DCH until 96 h after DCH. Reperfusion of the infarcted tissue was documented in a previous report. Cerebral lactate/pyruvate ratio (L/P) and lactate were significantly elevated in the infarcted tissue compared to the non-infarcted hemisphere (p < 0.05). From 12 to 96 h after DCH the pyruvate level was significantly higher in the infarcted tissue than in the non-infarcted hemisphere (p < 0.05). After a prolonged period of ischemia and subsequent reperfusion, cerebral tissue shows signs of protracted mitochondrial dysfunction, characterized by a marked increase in cerebral lactate level with a normal or increased cerebral pyruvate level resulting in an increased LP-ratio. This biochemical pattern contrasts to cerebral ischemia, which is characterized by a marked decrease in cerebral pyruvate. The study supports the hypothesis that it is possible to diagnose cerebral mitochondrial dysfunction and to separate it from cerebral ischemia by microdialysis and bed-side biochemical analysis.

Analyzing Thioflavin T Binding to Amyloid Fibrils by an Equilibrium Microdialysis-Based Technique

PubMed Central

Kuznetsova, Irina M.; Sulatskaya, Anna I.; Uversky, Vladimir N.; Turoverov, Konstantin K.

2012-01-01

A new approach for the determination of the amyloid fibril – thioflavin T (ThT) binding parameters (the number of binding modes, stoichiometry, and binding constants of each mode) is proposed. This approach is based on the absorption spectroscopy determination of the concentration of free and bound to fibril dye in solutions, which are prepared by equilibrium microdialysis. Furthermore, the proposed approach allowed us, for the first time, to determine the absorption spectrum, molar extinction coefficient, and fluorescence quantum yield of the ThT bound to fibril by each binding modes. This approach is universal and can be used for determining the binding parameters of any dye interaction with a receptor, such as ANS binding to proteins in the molten globule state or to protein amorphous aggregates. PMID:22383971

Analyzing thioflavin T binding to amyloid fibrils by an equilibrium microdialysis-based technique.

PubMed

Kuznetsova, Irina M; Sulatskaya, Anna I; Uversky, Vladimir N; Turoverov, Konstantin K

2012-01-01

A new approach for the determination of the amyloid fibril - thioflavin T (ThT) binding parameters (the number of binding modes, stoichiometry, and binding constants of each mode) is proposed. This approach is based on the absorption spectroscopy determination of the concentration of free and bound to fibril dye in solutions, which are prepared by equilibrium microdialysis. Furthermore, the proposed approach allowed us, for the first time, to determine the absorption spectrum, molar extinction coefficient, and fluorescence quantum yield of the ThT bound to fibril by each binding modes. This approach is universal and can be used for determining the binding parameters of any dye interaction with a receptor, such as ANS binding to proteins in the molten globule state or to protein amorphous aggregates.

N-terminal galanin-(1-16) fragment is an agonist at the hippocampal galanin receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fisone, G.; Berthold, M.; Bedecs, K.

1989-12-01

The galanin N-terminal fragment (galanin-(1-16)) has been prepared by solid-phase synthesis and by enzymic cleavage of galanin by endoproteinase Asp-N. This peptide fragment displaced {sup 125}I-labeled galanin in receptor autoradiography experiments on rat forebrain and spinal cord and in equilibrium binding experiments from high-affinity binding sites in the ventral hippocampus with an IC50 of approximately 3 nM. In tissue slices of the same brain area, galanin-(1-16), similarly to galanin, inhibited the muscarinic agonist-stimulated breakdown of inositol phospholipids. Upon intracerebroventricular administration, galanin-(1-16) (10 micrograms/15 microliters) also inhibited the scopolamine (0.3 mg/kg, s.c.)-evoked release of acetylcholine, as studied in vivo by microdialysis.more » Substitution of (L-Trp2) for (D-Trp2) resulted in a 500-fold loss in affinity as compared with galanin-(1-16). It is concluded that, in the ventral hippocampus, the N-terminal galanin fragment (galanin-(1-16)) is recognized by the galanin receptors controlling acetylcholine release and muscarinic agonist-stimulated inositol phospholipid breakdown as a high-affinity agonist and that amino acid residue (Trp2) plays an important role in the receptor-ligand interactions.« less

Comparison of extracellular striatal acetylcholine and brain seizure activity following acute exposure to the nerve agents cyclosarin and tabun in freely moving guinea pigs.

PubMed

O'Donnell, John C; Acon-Chen, Cindy; McDonough, John H; Shih, Tsung-Ming

2010-11-01

Organophosphorus nerve agents like cyclosarin and tabun are potent cholinesterase inhibitors. The inhibition of acetylcholinesterase, which is responsible for breaking down acetylcholine (ACh) at the synapse and neuromuscular junction, leads to a build-up of extracellular ACh and a series of toxic consequences including hypersecretion, tremor, convulsion/seizure, respiratory distress, coma, and death. This study employed simultaneous and continuous electroencephalographic recording and striatal microdialysis collection for quantification of ACh changes (via subsequent HPLC analysis) during acute exposure to a 1.0 × LD(50) subcutaneous dose of either cyclosarin or tabun to investigate differences in cholinergic and behavioral effects. Information about the unique mechanisms and consequences of different nerve agents is intended to aid in the development of broad-spectrum medical countermeasures for nerve agents. At the dose administered, non-seizure and sustained seizure responses were observed in both agent groups and in the tabun-exposed group some subjects experienced an unsustained seizure response. Significant extracellular ACh increases were only observed in seizure groups. Cyclosarin and tabun were found to exhibit some unique cholinergic and ictogenic characteristics. Lethality only occurred in subjects experiencing sustained seizure, and there was no difference in lethality between agent groups that progressed to sustained seizure.

Physiological and biochemical principles underlying volume-targeted therapy--the "Lund concept".

PubMed

Nordström, Carl-Henrik

2005-01-01

The optimal therapy of sustained increase in intracranial pressure (ICP) remains controversial. The volume-targeted therapy ("Lund concept") discussed in this article focuses on the physiological volume regulation of the intracranial compartments. The balance between effective transcapillary hydrostatic and osmotic pressures constitutes the driving force for transcapillary fluid exchange. The low permeability for sodium and chloride combined with the high crystalloid osmotic pressure (approximately 5700 mmHg) on both sides of the blood-brain barrier (BBB) counteracts fluid exchange across the intact BBB. Additionally, variations in systemic blood pressure generally are not transmitted to these capillaries because cerebral intracapillary hydrostatic pressure (and blood flow) is physio-logically tightly autoregulated. Under pathophysiological conditions, the BBB may be partially disrupted. Transcapillary water exchange is then determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Pressure autoregulation of cerebral blood flow is likely to be impaired in these conditions. A high cerebral perfusion pressure accordingly increases intracapillary hydrostatic pressure and leads to increased intracerebral water content and an increase in ICP. The volume-targeted "Lund concept" has been evaluated in experimental and clinical studies to examine the physiological and biochemical (utilizing intracerebral microdialysis) effects, and the clinical experiences have been favorable.

Effects of head-up vs. supine CPR on cerebral oxygenation and cerebral metabolism - a prospective, randomized porcine study.

PubMed

Putzer, Gabriel; Braun, Patrick; Martini, Judith; Niederstätter, Ines; Abram, Julia; Lindner, Andrea Katharina; Neururer, Sabrina; Mulino, Miriam; Glodny, Bernhard; Helbok, Raimund; Mair, Peter

2018-05-01

Recent studies have shown that during cardiopulmonary resuscitation (CPR) head-up position (HUP) as compared to standard supine position (SUP) decreases intracranial pressure (ICP) and increases cerebral perfusion pressure (CPP). The impact of this manoeuvre on brain oxygenation and metabolism is not clear. We therefore investigated HUP as compared to SUP during basic life support (BLS) CPR for their effect on brain oxygenation and metabolism. Twenty pigs were anaesthetized and instrumented. After 8 min of cardiac arrest (CA) pigs were randomized to either HUP or SUP and resuscitated mechanically for 20 min. Mean arterial pressure (MAP), ICP, CPP, cerebral regional oxygen saturation (rSO 2 ) and brain tissue oxygen tension (P bt O 2 ) were measured at baseline, after CA and every 5 min during CPR. Cerebral venous oxygen saturation (S cv O 2 ) was measured at baseline, after CA and after 20 min of CPR. Cerebral microdialysis parameters, e.g. lactate/pyruvate ratio (L/P ratio) were taken at baseline and the end of the experiment. ICP was significantly lower in HUP compared to SUP animals after 5 min (18.0 ± 4.5 vs. 24.1 ± 5.2 mmHg; p = 0.033) and 20 min (12.0 ± 3.4 vs. 17.8 ± 4.3 mmHg; p = 0.023) of CPR. Accordingly, CPP was significantly higher in the HUP group after 5 min (11.2 ± 9.5 vs. 1.0 ± 9.2 mmHg; p = 0.045) and 20 min (3.4 ± 6.4 vs. -3.8 ± 2.8 mmHg; p = 0.023) of CPR. However, no difference was found in rSO 2 , P bt O 2 , S cv O 2 and L/P ratio between groups after 20 min of CPR. In this animal model of BLS CPR, HUP as compared to SUP did not improve cerebral oxygenation or metabolism. Copyright © 2018. Published by Elsevier B.V.

BDNF–TrkB signaling in the nucleus accumbens shell of mice has key role in methamphetamine withdrawal symptoms

PubMed Central

Ren, Q; Ma, M; Yang, C; Zhang, J-C; Yao, W; Hashimoto, K

2015-01-01

Depression is a core symptom of methamphetamine (METH) withdrawal during the first several weeks of abstinence. However, the precise mechanisms underlying METH withdrawal symptoms remain unknown. Brain-derived neurotrophic factor (BDNF) and its specific receptor, tropomyosin-related kinase (TrkB), have a role the in pathophysiology of depression. In this study, we examined the role of BDNF–TrkB signaling in different brain regions of male mice with METH withdrawal symptoms. Repeated METH (3 mg kg−1 per day for 5 days) administration to mice caused a long-lasting depression-like behavior including anhedonia. Western blot analysis showed that BDNF levels in the nucleus accumbens (NAc) of METH-treated mice were significantly higher than those of control mice whereas BDNF levels in other regions, including the prefrontal cortex and hippocampus, were not altered. METH-induced depression-like behavior, behavioral sensitization and dendritic changes in the NAc shell were improved by subsequent subchronic administration of TrkB antagonist ANA-12 (0.5 mg kg−1 per day for 14 days), but not TrkB agonist 7,8-dihydroxyflavone (10 mg kg−1 per day for 14 days). In vivo microdialysis showed that METH (1 mg kg−1)-induced dopamine release in NAc shell of METH-treated mice was attenuated after subsequent subchronic ANA-12 administration. Interestingly, a single bilateral infusion of ANA-12 into the NAc shell, but not NAc core, showed a rapid and long-lasting therapeutic effect. However, ketamine and paroxetine had no effect. These findings suggest that increased BDNF–TrkB signaling in the NAc shell has an important role in the behavioral abnormalities after withdrawal from repeated METH administration, and that TrkB antagonists are potential therapeutic drugs for withdrawal symptoms in METH abusers. PMID:26506052

A Functional Tph2 C1473G Polymorphism Causes an Anxiety Phenotype via Compensatory Changes in the Serotonergic System

PubMed Central

Berger, Stefan M; Weber, Tillmann; Perreau-Lenz, Stephanie; Vogt, Miriam A; Gartside, Sarah E; Maser-Gluth, Christiane; Lanfumey, Laurence; Gass, Peter; Spanagel, Rainer; Bartsch, Dusan

2012-01-01

The association of single-nucleotide polymorphisms (SNPs) in the human tryptophan hydroxylase 2 (TPH2) gene with anxiety traits and depression has been inconclusive. Observed inconsistencies might result from the fact that TPH2 polymorphisms have been studied in a genetically heterogeneous human population. A defined genetic background, control over environmental factors, and the ability to analyze the molecular and neurochemical consequences of introduced genetic alterations constitute major advantages of investigating SNPs in inbred laboratory mouse strains. To investigate the behavioral and neurochemical consequences of a functional C1473G SNP in the mouse Tph2 gene, we generated congenic C57BL/6N mice homozygous for the Tph2 1473G allele. The Arg447 substitution in the TPH2 enzyme resulted in a significant reduction of the brain serotonin (5-HT) in vivo synthesis rate. Despite decreased 5-HT synthesis, we could detect neither a reduction of brain region-specific 5-HT concentrations nor changes in baseline and stress-induced 5-HT release using a microdialysis approach. However, using a [35S]GTP-γ-S binding assay and 5-HT1A receptor autoradiography, a functional desensitization of 5-HT1A autoreceptors could be identified. Furthermore, behavioral analysis revealed a distinct anxiety phenotype in homozygous Tph2 1473G mice, which could be reversed with chronic escitalopram treatment. Alterations in depressive-like behavior could not be detected under baseline conditions or after chronic mild stress. These findings provide evidence for an involvement of functional Tph2 polymorphisms in anxiety-related behaviors, which are likely not caused directly by alterations in 5-HT content or release but are rather due to compensatory changes during development involving functional desensitization of 5-HT1A autoreceptors. PMID:22491354

Pharmacological profile of opicapone, a third-generation nitrocatechol catechol-O-methyl transferase inhibitor, in the rat.

PubMed

Bonifácio, M J; Torrão, L; Loureiro, A I; Palma, P N; Wright, L C; Soares-da-Silva, P

2015-04-01

Catechol-O-methyltransferase (COMT) is an important target in the levodopa treatment of Parkinson's disease; however, the inhibitors available have problems, and not all patients benefit from their efficacy. Opicapone was developed to overcome those limitations. In this study, opicapone's pharmacological properties were evaluated as well as its potential cytotoxic effects. The pharmacodynamic effects of opicapone were explored by evaluating rat COMT activity and levodopa pharmacokinetics, in the periphery through microdialysis and in whole brain. The potential cytotoxicity risk of opicapone was explored in human hepatocytes by assessing cellular ATP content and mitochondrial membrane potential. Opicapone inhibited rat peripheral COMT with ED50 values below 1.4 mg⋅kg(-1) up to 6 h post-administration. The effect was sustained over the first 8 h and by 24 h COMT had not returned to control values. A single administration of opicapone resulted in increased and sustained plasma levodopa levels with a concomitant reduction in 3-O-methyldopa from 2 h up to 24 h post-administration, while tolcapone produced significant effects only at 2 h post-administration. The effects of opicapone on brain catecholamines after levodopa administration were sustained up to 24 h post-administration. Opicapone was also the least potent compound in decreasing both the mitochondrial membrane potential and the ATP content in human primary hepatocytes after a 24 h incubation period. Opicapone has a prolonged inhibitory effect on peripheral COMT, which extends the bioavailability of levodopa, without inducing toxicity. Thus, it exhibits some improved properties compared to the currently available COMT inhibitors. © 2014 The British Pharmacological Society.

The neuroprotective properties of the superoxide dismutase mimetic tempol correlate with its ability to reduce pathological glutamate release in a rodent model of stroke

PubMed Central

Dohare, Preeti; Hyzinski-García, María C.; Vipani, Aarshi; Bowens, Nicole H.; Nalwalk, Julia W.; Feustel, Paul J.; Keller, Richard W.; Jourd’heuil, David; Mongin, Alexander A.

2014-01-01

The contribution of oxidative stress to ischemic brain damage is well established. Nevertheless, for unknown reasons, several clinically tested antioxidant therapies failed to show benefits in human stroke. Based on our previous in vitro work, we hypothesized that the neuroprotective potency of antioxidants is related to their ability to limit release of the excitotoxic amino acids, glutamate and aspartate. We explored the effects of two antioxidants, tempol and edaravone, on amino acid release in the brain cortex, in a rat model of transient occlusion of the middle cerebral artery (MCAo). Amino acid levels were quantified using a microdialysis approach, with the probe positioned in the ischemic penumbra as verified by a laser Doppler technique. Two-hour MCAo triggered a dramatic increase in the levels of glutamate, aspartate, taurine and alanine. Microdialysate delivery of 10 mM tempol reduced the amino acid release by 60–80%, while matching levels of edaravone had no effect. In line with these latter data, an intracerebroventri-cular injection of tempol but not edaravone (500 nmols each, 15 minutes prior to MCAo) reduced infarction volumes by ~50% and improved neurobehavioral outcomes. In vitro assays showed that tempol was superior in removing superoxide anion, whereas edaravone was more potent in scavenging hydrogen peroxide, hydroxyl radical, and peroxynitrite. Overall, our data suggests that the neuroprotective properties of tempol are likely related to its ability to reduce tissue levels of the superoxide anion and pathological glutamate release, and, in such a way, limit progression of brain infarction within ischemic penumbra. These new findings may be instrumental in developing new antioxidant therapies for treatment of stroke. PMID:25224033

Monitoring in traumatic brain injury.

PubMed

Matz, P G; Pitts, L

1997-01-01

In the past several years, improvements in technology have advanced the monitoring capabilities for patients with TBI. The primary goal of monitoring the patient with TBI is to prevent secondary insults to the brain, primarily cerebral ischemia. Cerebral ischemia may occur early and without clinical correlation and portends a poor outcome. Measurement of ICP is the cornerstone of monitoring in the patient with TBI. Monitoring of ICP provides a measurement of CPP and a rough estimation of CBF. However, with alterations in pressure autoregulation, measurement of CPP does not always allow for determination of CBF. To circumvent this problem, direct measurements of CBF can be performed using clearance techniques (133Xe, N2O, Xe-CT) or invasive monitoring techniques (LDF, TDF, NIRS). Although direct and quantitative, clearance techniques do not allow for continuous monitoring. Invasive CBF monitoring techniques are new, and artifactual results can be problematic. The techniques of jugular venous saturation monitoring and TCD are well established and are powerful adjuncts to ICP monitoring. They allow the clinician to monitor cerebral oxygen extraction and blood flow velocity, respectively, for any given CPP. Use of TCD may predict posttraumatic vasospasm before clinical sequelae. Jugular venous saturation monitoring may detect clinically occult episodes of cerebral ischemia and increased oxygen extraction. Jugular venous saturation monitoring optimizes the use of hyperventilation in the treatment of intracranial hypertension. Although PET and SPECT scanning allow direct measurement of CMRO2, these techniques have limited application currently. Similarly, microdialysis is in its infancy but has demonstrated great promise for metabolic monitoring. EEG and SEP are excellent adjuncts to the monitoring arsenal and provide immediate information on current brain function. With improvements in electronic telemetry, functional monitoring by EEG or SEP may become an important part of routine monitoring in TBI.

Modulation of sibutramine-induced increases in extracellular noradrenaline concentration in rat frontal cortex and hypothalamus by α2-adrenoceptors

PubMed Central

Wortley, K E; Heal, D J; Stanford, S C

1999-01-01

The effects of sibutramine (0.25–10 mg kg−1 i.p.) on extracellular noradrenaline concentration in the frontal cortex and hypothalamus of freely-moving rats were investigated using microdialysis. The role of presynaptic α2-adrenoceptors in modulating the effects of sibutramine in these brain areas was also determined.Sibutramine induced an increase in extracellular noradrenaline concentration, the magnitude of which paralleled dose, in both brain areas. In the cortex, this increase was gradual and sustained, whereas in the hypothalamus it was more rapid and of shorter duration.In both the cortex and hypothalamus, pretreatment of rats with the α2-adrenoceptor antagonist RX821002 (3 mg kg−1 i.p.) potentiated increases in the accumulation of extracellular noradrenaline induced by sibutramine (10 mg kg−1 i.p.), by 7 and 10 fold respectively. RX821002 also reduced the latency of sibutramine to reach its maximum effect in the cortex, but not in the hypothalamus.Infusion of RX821002 (1 μM) via the probe increased the accumulation of extracellular noradrenaline induced by sibutramine (10 mg kg−1 i.p.) in both brain areas. In the hypothalamus, the effects of RX821002 on the accumulation of noradrenaline induced by sibutramine were 2 fold greater than those in the cortex.These findings support evidence that sibutramine inhibits the reuptake of noradrenaline in vivo, but that the accumulation of extracellular noradrenaline is limited by noradrenergic activation of presynaptic α2-adrenoceptors. Furthermore, the data suggest that terminal α2-adrenoceptors in the hypothalamus exert a greater inhibitory effect over the control of extracellular noradrenaline accumulation than do those in the cortex. PMID:10516646

Development of intraoperative electrochemical detection: wireless instantaneous neurochemical concentration sensor for deep brain stimulation feedback

PubMed Central

Van Gompel, Jamie J.; Chang, Su-Youne; Goerss, Stephan J.; Kim, In Yong; Kimble, Christopher; Bennet, Kevin E.; Lee, Kendall H.

2010-01-01

Deep brain stimulation (DBS) is effective when there appears to be a distortion in the complex neurochemical circuitry of the brain. Currently, the mechanism of DBS is incompletely understood; however, it has been hypothesized that DBS evokes release of neurochemicals. Well-established chemical detection systems such as microdialysis and mass spectrometry are impractical if one is assessing changes that are happening on a second-to-second time scale or for chronically used implanted recordings, as would be required for DBS feedback. Electrochemical detection techniques such as fast-scan cyclic voltammetry (FSCV) and amperometry have until recently remained in the realm of basic science; however, it is enticing to apply these powerful recording technologies to clinical and translational applications. The Wireless Instantaneous Neurochemical Concentration Sensor (WINCS) currently is a research device designed for human use capable of in vivo FSCV and amperometry, sampling at subsecond time resolution. In this paper, the authors review recent advances in this electrochemical application to DBS technologies. The WINCS can detect dopamine, adenosine, and serotonin by FSCV. For example, FSCV is capable of detecting dopamine in the caudate evoked by stimulation of the subthalamic nucleus/substantia nigra in pig and rat models of DBS. It is further capable of detecting dopamine by amperometry and, when used with enzyme linked sensors, both glutamate and adenosine. In conclusion, WINCS is a highly versatile instrument that allows near real-time (millisecond) detection of neurochemicals important to DBS research. In the future, the neurochemical changes detected using WINCS may be important as surrogate markers for proper DBS placement as well as the sensor component for a “smart” DBS system with electrochemical feedback that allows automatic modulation of stimulation parameters. Current work is under way to establish WINCS use in humans. PMID:20672923

On the Accuracy of In Vivo Ethanol and Acetaldehyde Monitoring, a Key Tile in the Puzzle of Acetaldehyde as a Neuroactive Agent.

PubMed

Enrico, Paolo; Diana, Marco

2017-01-01

Over the last 20 years researchers have explored the postulated role of acetaldehyde (ACD) as a mediator of some of the actions of ethanol (EtOH) in the central nervous system (CNS). However, efforts have been hampered mainly by the difficulty of directly measuring in vivo EtOH and ACD levels in the CNS and thus, our knowledge is based on indirect evidences. Although technically challenging, the development of reliable methods for in vivo measurement of ACD and EtOH is of paramount importance to solve the " puzzle of acetaldehyde as a neuroactive agent. " In this short review we discuss the recent advances on brain EtOH pharmacokinetic and state-of-the-art available techniques that could be used for in vivo detect EtOH and ACD both non-invasively (magnetic resonance spectroscopy), and invasively (microdialysis and biosensors). Among the different in vivo sampling techniques described, particular emphasis is paid to the field of enzyme-based amperometric biosensors. Biosensors have gained much attention in recent years for their ability to online monitor biological signals in vivo , and several micro- and nano-structured devices have been successfully used for in vivo studies. Owing to their high temporal and spatial resolution, biosensors could provide the adequate technology for studying in vivo EtOH pharmacokinetic.

Functional Analysis of Dopaminergic Systems in a DYT1 Knock-in Mouse Model of Dystonia

PubMed Central

Song, Chang-Hyun; Fan, Xueliang; Exeter, Cicely J.; Hess, Ellen J.; Jinnah, H. A.

2012-01-01

The dystonias are a group of disorders characterized by involuntary twisting movements and abnormal posturing. The most common of the inherited dystonias is DYT1 dystonia, which is due to deletion of a single GAG codon (ΔE) in the TOR1A gene that encodes torsinA. Since some forms of dystonia have been linked with dysfunction of brain dopamine pathways, the integrity of these pathways was explored in a knock-in mouse model of DYT1 dystonia. In DYT1(ΔE) knock-in mice, neurochemical measures revealed only small changes in the content of dopamine or its metabolites in tissue homogenates from caudoputamen or midbrain, but microdialysis studies revealed robust decreases in baseline and amphetamine-stimulated extracellular dopamine in the caudoputamen. Quantitative stereological methods revealed no evidence for striatal or midbrain atrophy, but substantia nigra neurons immunopositive for tyrosine hydroxylase were slightly reduced in numbers and enlarged in size. Behavioral studies revealed subtle abnormalities in gross motor activity and motor coordination without overt dystonia. Neuropharmacological challenges of dopamine systems revealed normal behavioral responses to amphetamine and a minor increase in sensitivity to haloperidol. These results demonstrate that this DYT1(ΔE) knock-in mouse model of dystonia harbors neurochemical and structural changes of the dopamine pathways, as well as motor abnormalities. PMID:22659308

Effect of Melanotan-II on Brain Fos Immunoreactivity and Oxytocin Neuronal Activity and Secretion in Rats.

PubMed

Paiva, L; Sabatier, N; Leng, G; Ludwig, M

2017-02-01

Melanocortins stimulate the central oxytocin systems that are involved in regulating social behaviours. Alterations in central oxytocin have been linked to neurological disorders such as autism, and melanocortins have been proposed for therapeutic treatment. In the present study, we investigated how systemic administration of melanotan-II (MT-II), a melanocortin agonist, affects oxytocin neuronal activity and secretion in rats. The results obtained show that i.v., but not intranasal, administration of MT-II markedly induced Fos expression in magnocellular neurones of the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus, and this response was attenuated by prior i.c.v. administration of the melanocortin antagonist, SHU-9119. Electrophysiological recordings from identified magnocellular neurones of the SON showed that i.v. administration of MT-II increased the firing rate in oxytocin neurones but did not trigger somatodendritic oxytocin release within the SON as measured by microdialysis. Our data suggest that, after i.v., but not intranasal, administration of MT-II, the activity of magnocellular neurones of the SON is increased. Because previous studies showed that SON oxytocin neurones are inhibited in response to direct application of melanocortin agonists, the actions of i.v. MT-II are likely to be mediated at least partly indirectly, possibly by activation of inputs from the caudal brainstem, where MT-II also increased Fos expression. © 2016 British Society for Neuroendocrinology.

Topical penetration of commercial salicylate esters and salts using human isolated skin and clinical microdialysis studies

PubMed Central

Cross, Sheree E; Anderson, Chris; Roberts, Michael S

1998-01-01

Aims The penetration of active ingredients from topically applied anti-inflammatory pharmaceutical products into tissues below the skin is the basis of their therapeutic efficacy. There is still controversy as to whether these agents are capable of direct penetration by diffusion through the tissues or whether redistribution in the systemic circulation is responsible for their tissue deposition below the application site. Methods The extent of direct penetration of salicylate from commercial ester and salt formulations into the dermal and subcutaneous tissue of human volunteers was determined using the technique of cutaneous microdialysis. We also examined differences in the extent of hydrolysis of the methylester of salicylate applied topically in human volunteers and in vitro skin diffusion cells using full-thickness skin and epidermal membranes. Results The present study showed that whilst significant levels of salicylate could be detected in the dermis and subcutaneous tissue of volunteers treated with the methylsalicylate formulation, negligible levels of salicylate were seen following application of the triethanolamine salicylate formulation. The tissue levels of salicylate from the methylsalicylate formulation were approx. 30-fold higher than the plasma concentrations. Conclusion The absorption and tissue concentration profiles for the commercial methylsalicylate formulation are indicative of direct tissue penetration and not solely redistribution by the systemic blood supply. PMID:9690946

Target-Triggered Switching on and off the Luminescence of Lanthanide Coordination Polymer Nanoparticles for Selective and Sensitive Sensing of Copper Ions in Rat Brain.

PubMed

Huang, Pengcheng; Wu, Fangying; Mao, Lanqun

2015-07-07

Copper ions (Cu(2+)) in the central nervous system play a crucial role in the physiological and pathological events, so simple, selective, and sensitive detection of cerebral Cu(2+) is of great importance. In this work, we report a facile yet effective fluorescent method for sensing of Cu(2+) in rat brain using one kind of lanthanide coordination polymer nanoparticle, adenosine monophosphate (AMP) and terbium ion (Tb(3+)), i.e., AMP-Tb, as the sensing platform. Initially, a cofactor ligand, 5-sulfosalicylic acid (SSA), as the sensitizer, was introduced into the nonluminescent AMP-Tb suspension, resulting in switching on the luminescence of AMP-Tb by the removal of coordinating water molecules and concomitant energy transfer from SSA to Tb(3+). The subsequent addition of Cu(2+) into the resulting SSA/AMP-Tb can strongly quench the fluorescence because the specific coordination interaction between SSA and Cu(2+) rendered energy transfer from SSA to Tb(3+) inefficient. The decrease ratio of the fluorescence intensities of SSA/AMP-Tb at 550 nm show a linear relationship for Cu(2+) within the concentration range from 1.5 to 24 μM with a detection limit of 300 nM. The method demonstrated here is highly selective and is free from the interference of metal ions, amino acids, and the biological species commonly existing in the brain such as dopamine, lactate, and glucose. Eventually, by combining the microdialysis technique, the present method has been successfully applied in the detection of cerebral Cu(2+) in rat brain with the basal dialysate level of 1.91 ± 0.40 μM (n = 3). This method is very promising to be used for investigating the physiological and pathological events that cerebral Cu(2+) participates in.

Cortical and sub-cortical effects in primate models of cocaine use: implications for addiction and the increased risk of psychiatric illness.

PubMed

Bradberry, Charles W

2011-02-01

Drug abuse is a serious risk factor for the incidence and severity of multiple psychiatric illnesses. Understanding the neurobiological consequences of repeated exposure to abused drugs can help to inform how those risks are manifested in terms of specific neurochemical mechanisms and brain networks. This review examines selective studies in non-human primates that employed a cocaine self-administration model. Neurochemical consequences of chronic exposure appear to differ from observations in rodent studies. Whereas chronic intermittent exposure in the rodent is usually associated with a dose-dependent increase in dopaminergic response to a cocaine challenge, in the rhesus monkey, high cumulative exposure was not observed to cause a sensitized dopamine response. These non-human primate observations are concordant with clinical findings in human users. The results of cue exposure studies on dopaminergic transmission are also reviewed. Direct microdialysis measurements indicate that there is not a sustained increase in dopamine associated with cocaine-linked cues. As an alternative to striatal dopaminergic mechanisms mediating cue effects, single unit studies in prefrontal cortex during self-administration in monkeys suggests the orbitofrontal and anterior cingulate cortex are strongly engaged by cocaine cues. Based on the strong clinical imaging literature on cortical and cognitive dysfunction associated with addiction, it is proposed that the strong engagement of cortical systems during repeated cocaine reinforcement results in maladaptive changes that contribute to the risks of drug use for exacerbation of other psychiatric disorders.

Glutamatergic transmission in the nucleus of the solitary tract modulates memory through influences on amygdala noradrenergic systems.

PubMed

Miyashita, Teiko; Williams, Cedric L

2002-02-01

The authors examined whether glutamate release from the vagus nerve onto the nucleus of the solitary tract (NTS) is one mechanism by which the vagus influences memory and neural activity in limbic structures. Rats trained to drink from a spout were given a footshock (0.35 mA) on Day 5 after approaching the spout. Phosphate-buffered saline or 5.0, 50.0, or 100.0 nmol/0.5 microl glutamate was then infused into the NTS. Glutamate (5.0 or 50.0 nmol) significantly enhanced memory on the retention test. In Experiment 2, this effect was attenuated by blocking noradrenergic receptors in the amygdala with propranolol (0.3 microg/0.5 microl). Experiment 3 used in vivo microdialysis to determine whether footshock plus glutamate (50.0 nmol) alters noradrenergic output in the amygdala. These treatments caused a significant and long-lasting increase in amygdala noradrenergic concentrations. The results indicate that glutamate may be one transmitter that conveys the effects of vagal activation on brain systems that process memory.

Ethyl cellulose nanocarriers and nanocrystals differentially deliver dexamethasone into intact, tape-stripped or sodium lauryl sulfate-exposed ex vivo human skin - assessment by intradermal microdialysis and extraction from the different skin layers.

PubMed

Döge, Nadine; Hönzke, Stefan; Schumacher, Fabian; Balzus, Benjamin; Colombo, Miriam; Hadam, Sabrina; Rancan, Fiorenza; Blume-Peytavi, Ulrike; Schäfer-Korting, Monika; Schindler, Anke; Rühl, Eckart; Skov, Per Stahl; Church, Martin K; Hedtrich, Sarah; Kleuser, Burkhard; Bodmeier, Roland; Vogt, Annika

2016-11-28

Understanding penetration not only in intact, but also in lesional skin with impaired skin barrier function is important, in order to explore the surplus value of nanoparticle-based drug delivery for anti-inflammatory dermatotherapy. Herein, short-term ex vivo cultures of (i) intact human skin, (ii) skin pretreated with tape-strippings and (iii) skin pre-exposed to sodium lauryl sulfate (SLS) were used to assess the penetration of dexamethasone (Dex). Intradermal microdialysis was utilized for up to 24h after drug application as commercial cream, nanocrystals or ethyl cellulose nanocarriers applied at the therapeutic concentration of 0.05%, respectively. In addition, Dex was assessed in culture media and extracts from stratum corneum, epidermis and dermis after 24h, and the results were compared to those in heat-separated split skin from studies in Franz diffusion cells. Providing fast drug release, nanocrystals significantly accelerated the penetration of Dex. In contrast to the application of cream and ethyl cellulose nanocarriers, Dex was already detectable in eluates after 6h when applying nanocrystals on intact skin. Disruption of the skin barrier further accelerated and enhanced the penetration. Encapsulation in ethyl cellulose nanocarriers delayed Dex penetration. Interestingly, for all formulations highly increased concentrations in the dialysate were observed in tape-stripped skin, whereas the extent of enhancement was less in SLS-exposed skin. The results were confirmed in tissue extracts and were in line with the predictions made by in vitro release studies and ex vivo Franz diffusion cell experiments. The use of 45kDa probes further enabled the collection of inflammatory cytokines. However, the estimation of glucocorticoid efficacy by Interleukin (IL)-6 and IL-8 analysis was limited due to the trauma induced by the probe insertion. Ex vivo intradermal microdialysis combined with culture media analysis provides an effective, skin-sparing method for preclinical assessment of novel drug delivery systems at therapeutic doses in models of diseased skin. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the Levels of Pro-Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle – A Microdialysis Study

PubMed Central

Christidis, Nikolaos; Ghafouri, Bijar; Larsson, Anette; Palstam, Annie; Mannerkorpi, Kaisa; Bileviciute-Ljungar, Indre; Löfgren, Monika; Bjersing, Jan; Kosek, Eva; Gerdle, Björn; Ernberg, Malin

2015-01-01

Objective Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repetitive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions. Material and Methods 32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour microdialysis session, to sample IL-1β, IL-6, IL-8, and TNF from the most painful point of the vastus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0–100) and fatigue Borg’s Rating of Perceived Exertion Scale; 6–20) were assessed before and during the entire microdialysis session. Results The repetitive dynamic contractions increased pain in the patients with fibromyalgia (P < .001) and induced fatigue in both groups (P < .001). Perceived fatigue was significantly higher among patients with fibromyalgia than controls (P < .001). The levels of IL-1β did not change during contractions in either group. The levels of TNF did not change during contractions in patients with fibromyalgia, but increased in controls (P < .001) and were significantly higher compared to patients with fibromyalgia (P = .033). The levels of IL-6 and IL-8 increased in both groups alike during and after contractions (P’s < .001). There were no correlations between pain or fatigue and cytokine levels after contractions. Conclusion There were no differences between patients with fibromyalgia and controls in release of pro-inflammatory cytokines, and no correlations between levels of pro-inflammatory cytokines and pain or fatigue. Thus, this study indicates that IL-1β, IL-6, IL-8, and TNF do not seem to play an important role in maintenance of muscle pain in fibromyalgia. PMID:26624891

A novel dynamic approach for automatic microsampling and continuous monitoring of metal ion release from soils exploiting a dedicated flow-through microdialyser.

PubMed

Miró, Manuel; Jimoh, Modupe; Frenzel, Wolfgang

2005-05-01

In this paper, a novel concept is presented for automatic microsampling and continuous monitoring of metal ions in soils with minimum disturbance of the sampling site. It involves a hollow-fiber microdialyser that is implanted in the soil body as a miniaturized sensing device. The idea behind microdialysis in this application is to mimic the function of a passive sampler to predict the actual, rather than potential, mobility and bioavailability of metal traces. Although almost quantitative dialysis recoveries were obtained for lead (> or = 98%) from aqueous model solutions with sufficiently long capillaries (l > or = 30 mm, 200 microm i.d.) at perfusion rates of 2.0 microL min(-1), the resistance of an inert soil matrix was found to reduce metal uptake by 30%. Preliminary investigation of the potential of the microdialysis analyser for risk assessment of soil pollution, and for metal partitioning studies, were performed by implanting the dedicated probe in a laboratory-made soil column and hyphenating it with electrothermal atomic absorption spectrometry (ETAAS), so that minute, well-defined volumes of clean microdialysates were injected on-line into the graphite furnace. A noteworthy feature of the implanted microdialysis-based device is the capability to follow the kinetics of metal release under simulated natural scenarios or anthropogenic actions. An ancillary flow set-up was arranged in such a way that a continuous flow of leaching solution--mild extractant (10(-2) mol L(-1) CaCl2), acidic solution (10(-3) mol L(-1) HNO3), or chelating agent (10(-4) or 10(-2) mol L(-1) EDTA)--was maintained through the soil body, while the concentration trends of inorganic (un-bound) metal species at the soil-liquid interface could be monitored at near real-time. Hence, relevant qualitative and quantitative information about the various mobile fractions is obtained, and metal-soil phase associations can also be elucidated. Finally, stimulus-response schemes adapted from neurochemical applications and pharmacokinetic studies are to be extended to soil research as an alternative means of local monitoring of extraction processes after induction of a chemical change in the outer boundary of the permselective dialysis membrane.

The long pursued Holy Grail of the true "alcoholic" rat.

PubMed

Gessa, Gian Luigi

2016-08-15

An anthology of microdialysis and electrophysiological studies on ethanol effect on mesolimbic dopaminergic neurons is presented. The usefulness of rats with innate preference for ethanol, such as the Sardinian alcohol-preferring (sP), in studying ethanol rewarding and reinforcing effects is signaled. The generation of the long sought "alcoholics rat" from sP rats is announced. Rats of the sP line avoid the shortcomings of using rats non selected for ethanol preference. Copyright © 2016. Published by Elsevier B.V.

The effects of postnatal alcohol exposure and galantamine on the context pre-exposure facilitation effect and acetylcholine efflux using in vivo microdialysis.

PubMed

Perkins, Amy E; Fadel, Jim R; Kelly, Sandra J

2015-05-01

Fetal alcohol spectrum disorders (FASD) are characterized by damage to multiple brain regions, including the hippocampus, which is involved in learning and memory. The acetylcholine neurotransmitter system provides major input to the hippocampus and is a possible target of developmental alcohol exposure. Alcohol (3.0 g/kg/day) was administered via intubation to male rat pups (postnatal day [PD] 2-10; ethanol-treated [ET]). Controls received a sham intubation (IC) or no treatment (NC). Acetylcholine efflux was measured using in vivo microdialysis (PD 32-35). ET animals were not different at baseline, but had decreased K(+)/Ca(2+)-induced acetylcholine efflux compared to NC animals and an enhanced acetylcholine response to galantamine (acetylcholinesterase inhibitor; 2.0 mg/kg) compared to both control groups. A separate cohort of animals was tested in the context pre-exposure facilitation effect task (CPFE; PD 30-32) following postnatal alcohol exposure and administration of galantamine (2.0 mg/kg; PD 11-30). Neither chronic galantamine nor postnatal alcohol exposure influenced performance in the CPFE task. Using immunohistochemistry, we found that neither alcohol exposure nor behavioral testing significantly altered the density of vesicular acetylcholine transporter or alpha7 nicotinic acetylcholine receptor in the ventral hippocampus (CA1). In the medial septum, the average number of choline acetyltransferase (ChAT+) cells was increased in ET animals that displayed the context-shock association; there were no changes in IC and NC animals that learned the context-shock association or in any animals that were in the control task that entailed no learning. Taken together, these results indicate that the hippocampal acetylcholine system is significantly disrupted under conditions of pharmacological manipulations (e.g., galantamine) in alcohol-exposed animals. Furthermore, ChAT was up‑regulated in ET animals that learned the CPFE, which may account for their ability to perform this task. In sum, developmental alcohol exposure may disrupt learning and memory in adolescence via a cholinergic mechanism. Copyright © 2015 Elsevier Inc. All rights reserved.

Combining Microdialysis and Electrophysiology in Cerebral Cortex to Delineate Functional Implications of Acetylcholine Gradients

NASA Astrophysics Data System (ADS)

Nelson, Kari L.

The neuronal network in cerebral cortex is a dynamic system that can undergo changes in collective neural activity as the organism changes its behavior. For example, during sleep and quiet restful awake state, many neurons tend to fire together in synchrony. In contrast, during alert awake states, firing patterns of neurons tend to be more asynchronous, firing more independently. These changes in population-level synchrony are defined as changes in cortical state. Response to sensory input is state-dependent, i.e., change in cortical state can impact the sensory information processing in cortex and introduce trial-to-trial variability in response to the same repeated stimuli. How the brain maintains reliable perception in spite of such trial-to-trial variability is a longstanding important question in neuroscience research. This dissertation is centered on two hypotheses. The first hypothesis is that different parts of the cortex can be in different states simultaneously. The second hypothesis is that inhomogeneity in cortical states can benefit the system by enabling the cortical network to maintain reliable sensory detection. If one part of the system is in a state that is not good for detection, then another part of the system could be in a different state that is good for detection, thus compensating and maintaining good detection for the system as a whole. These hypotheses were tested on anesthetized rats and awake mice. In anesthetized rats, cholinergic neuromodulation via microdialysis (muD) probes was used to induce cortical state changes in the somatosensory barrel cortex. Changes in cortical state and response to whisker stimulus was recorded with a microelectrode array (MEA). In awake mice, nucleus basalis was optogenetically stimulated by inserting an optic fiber in basal forebrain and response to visual stimulus was analyzed. The results demonstrated heterogeneity in cortical state across the spatial extent of cortical network. Changes in sensory response followed this heterogeneity and sensory detection was not reliable at the level of single neurons or small regions of cortex. The greater population of neurons, on the other hand, maintained reliable sensory detection, suggesting that heterogeneous state can be functionally beneficial for the cortical network.

Early metabolic responses to lithium/pilocarpine-induced status epilepticus in rat brain.

PubMed

Imran, Imran; Hillert, Markus H; Klein, Jochen

2015-12-01

The lithium-pilocarpine model of status epilepticus is a well-known animal model of temporal lobe epilepsy. We combined this model with in vivo microdialysis to investigate energy metabolites and acute cellular membrane damage during seizure development. Rats were implanted with dialysis probes and pretreated with lithium chloride (127 mg/kg i.p.). Twenty-four hours later, they received pilocarpine (30 mg/kg s.c.) which initiated seizures within 30 min. In the dialysate from rat hippocampus, we observed a transient increase in glucose and a prominent, five-fold increase in lactate during seizures. Lactate release was because of neuronal activation as it was strongly reduced by infusion of tetrodotoxin, administration of atropine or when seizures were terminated by diazepam or ketamine. In ex vivo assays, mitochondrial function as measured by respirometry was not affected by 90 min of seizures. Extracellular levels of choline, however, increased two-fold and glycerol levels 10-fold, which indicate cellular phospholipid breakdown during seizures. Within 60 min of pilocarpine administration, hydroxylation of salicylate increased two-fold and formation of isoprostanes 20-fold, revealing significant oxidative stress in hippocampal tissue. Increases in lactate, glycerol and isoprostanes were abrogated, and increases in choline were completely prevented, when hippocampal probes were perfused with calcium-free solution. Similarly, administration of pregabalin (100 mg/kg i.p.), a calcium channel ligand, 15 min prior to pilocarpine strongly attenuated parameters of membrane damage and oxidative stress. We conclude that seizure development in a rat model of status epilepticus is accompanied by increases in extracellular lactate, choline and glycerol, and by oxidative stress, while mitochondrial function remains intact for at least 90 min. Membrane damage depends on calcium influx and can be prevented by treatment with pregabalin. Status epilepticus (SE) was induced in rats by lithium-pilocarpine ('Pilo') administration, and extracellular metabolites were measured by microdialysis. Seizures caused several-fold increases in lactate levels which were attenuated by diazepam ('Diaz'), ketamine, atropine and tetrodotoxin (TTX). Indicators of oxidative stress and membrane damage were also increased during seizures. Omission of calcium and pregabalin, a calcium channel blocker, reduced cellular damage induced by SE. © 2015 International Society for Neurochemistry.

Reduced prefrontal dopaminergic activity in valproic acid-treated mouse autism model.

PubMed

Hara, Yuta; Takuma, Kazuhiro; Takano, Erika; Katashiba, Keisuke; Taruta, Atsuki; Higashino, Kosuke; Hashimoto, Hitoshi; Ago, Yukio; Matsuda, Toshio

2015-08-01

Previous studies suggest that dysfunction of neurotransmitter systems is associated with the pathology of autism in humans and the disease model rodents, but the precise mechanism is not known. Rodent offspring exposed prenatally to VPA shows autism-related behavioral abnormalities. The present study examined the effect of prenatal VPA exposure on brain monoamine neurotransmitter systems in male and female mice. The prenatal VPA exposure did not affect the levels of dopamine (DA), noradrenaline (NA), serotonin (5-HT) and their metabolites in the prefrontal cortex and striatum, while it significantly reduced methamphetamine (METH) (1.0 mg/kg)-induced hyperlocomotion in male offspring. In vivo microdialysis study demonstrated that prenatal VPA exposure attenuated METH-induced increases in extracellular DA levels in the prefrontal cortex, while it did not affect those in extracellular NA and 5-HT levels. Prenatal VPA exposure also decreased METH-induced c-Fos expression in the prefrontal cortex and the mRNA levels of DA D1 and D2 receptors in the prefrontal cortex. These effects of VPA were not observed in the striatum. In contrast to male offspring, prenatal VPA exposure did not affect METH-induced increases in locomotor activity and prefrontal DA levels and the D1 and D2 receptor mRNA levels in the prefrontal cortex in female offspring. These findings suggest that prenatal VPA exposure causes hypofunction of prefrontal DA system in a sex-dependent way. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection of basal acetylcholine release in the microdialysis of rat frontal cortex by high-performance liquid chromatography using a horseradish peroxidase-osmium redox polymer electrode with pre-enzyme reactor.

PubMed

Kato, T; Liu, J K; Yamamoto, K; Osborne, P G; Niwa, O

1996-06-28

To determine the basal acetylcholine level in the dialysate of rat frontal cortex, a horseradish peroxidase-osmium redox polymer-modified glassy carbon electrode (HRP-GCE) was employed instead of the conventional platinum electrode used in high-performance liquid chromatography-electrochemical detection (HPLC-ED). In initial experiments, an oxidizable unknown compound interfered with the detection of basal acetylcholine release on HPLC-HRP-GCE. An immobilized peroxidase-choline oxidase precolumn (pre-reactor) was included in the HPLC system, to eliminate the interference from the unknown compound. This combination could detect less than 10 fmol of standard acetylcholine and basal acetylcholine levels in the dialysate from a conventional concentric design microdialysis probe, without the use of cholinesterase inhibitor, and may facilitate physiological investigation of cholinergic neuronal activity in the central nervous system.

Caffeine potentiates the enhancement by choline of striatal acetylcholine release

NASA Technical Reports Server (NTRS)

Johnson, D. A.; Ulus, I. H.; Wurtman, R. J.

1992-01-01

We investigated the effect of peripherally administered caffeine (50 mg/kg), choline (30, 60, or 120 mg/kg) or combinations of both drugs on the spontaneous release of acetylcholine (ACh) from the corpus striatum of anesthetized rats using in vivo microdialysis. Caffeine alone or choline in the 30 or 60 mg/kg dose failed to increase ACh in microdialysis samples; the 120 mg/kg choline dose significantly enhanced ACh during the 80 min following drug administration. Coadministration of caffeine with choline significantly increased ACh release after each of the choline doses tested. Peak microdialysate levels with the 120 mg/kg dose were increased 112% when caffeine was additionally administered, as compared with 54% without caffeine. These results indicate that choline administration can enhance spontaneous ACh release from neurons, and that caffeine, a drug known to block adenosine receptors on these neurons, can amplify the choline effect.

Central l-proline attenuates stress-induced dopamine and serotonin metabolism in the chick forebrain.

PubMed

Hamasu, Kousuke; Shigemi, Kazutaka; Kabuki, Yusuke; Tomonaga, Shozo; Denbow, D Michael; Furuse, Mitsuhiro

2009-08-21

Using microdialysis, we investigated the effect of l-proline on monoamine release in the medio-rostral neostriatum/hyperstriatum ventrale (MNH) of freely moving and restricted chicks. A 30 min handling-stress resulted in a significant increase in extracellular homovallinic acid (HVA), a dopamine metabolite, and 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite, in the MNH. l-Proline, perfused through the microdialysis probe into the MNH during the stressed condition, significantly attenuated the average dialysate concentration of HVA produced by handling-stress. Handling-stress resulted in a significant increase in 5-HIAA levels in the control group, which were attenuated by profusion with l-proline. l-Proline did not significantly modify basal concentrations of HVA or 5-HIAA in the MNH during control conditions. These results show that perfusion of l-proline modified the turnover/metabolism of dopamine and serotonin in the MNH caused by handling-stress.

Microdialysis unit for molecular weight separation

DOEpatents

Smith, Richard D.; Liu, Chuanliang

1999-01-01

The present invention relates generally to an apparatus and method for separating high molecular weight molecules from low molecular weight molecules. More specifically, the invention relates to the use of microdialysis for removal of the salt (low molecular weight molecules) from a nucleotide sample (high molecular weight molecules) for ESI-MS analysis. The dialysis or separation performance of the present invention is improved by (1) increasing dialysis temperature thereby increasing desalting efficiency and improving spectrum quality; (2) adding piperidine and imidazole to the dialysis buffer solution and reducing charge states and further increasing detection sensitivity for DNA; (3) using low concentrations (0-2.5 mM NH4OAc) of dialysis buffer and shifting the DNA negative ions to higher charge states, producing a nearly 10-fold increase in detection sensitivity and a slightly decreased desalting efficiency, or (4) any combination of (1), (2), and (3).

Regulation of striatal nitric oxide synthesis by local dopamine and glutamate interactions

PubMed Central

Park, Diana J.; West, Anthony R.

2009-01-01

Nitric oxide (NO) is a key neuromodulator of corticostriatal synaptic transmission. We have shown previously that dopamine (DA) D1/5 receptor stimulation facilitates neuronal NO synthase (nNOS) activity in the intact striatum. To study the impact of local manipulations of D1/5 and glutamatergic NMDA receptors on striatal nNOS activity, we combined the techniques of in vivo amperometry and reverse microdialysis. Striatal NO efflux was monitored proximal to the microdialysis probe in urethane anesthetized rats during local infusion of vehicle or drug. NO efflux elicited by systemic administration of SKF-81297 was blocked following intrastriatal infusion of: 1) the D1/5 receptor antagonist SCH-23390, 2) the nNOS inhibitor 7-nitroindazole, 3) the nonspecific ionotropic glutamate receptor antagonist kynurenic acid, and 4) the selective NMDA receptor antagonist 3-phosphonopropyl-piperazine-2-carboxylic acid. Glycine coperfusion did not affect SKF-81297-induced NO efflux. Furthermore, intrastriatal infusion of SKF-81297 potentiated NO efflux evoked during electrical stimulation of the motor cortex. The facilitatory effects of cortical stimulation and SKF-81297 were both blocked by intrastriatal infusion of SCH-23390, indicating that striatal D1/5 receptor activation is necessary for the activation of nNOS by corticostriatal afferents. These studies demonstrate for the first time that reciprocal DA-glutamate interactions play a critical role in stimulating striatal nNOS activity. PMID:19799710

Cutaneous microdialysis as a novel means of continuously stimulating eccrine sweat glands in vivo.

PubMed

Morgan, Caroline J; Friedmann, Peter S; Church, Martin K; Clough, Geraldine F

2006-06-01

Previous studies of the pharmacological regulation of sweat gland function in humans have administered agonists or antagonists systemically, by local intradermal injection or by iontophoresis. This has not allowed prolonged or steady-state activation of sweat glands to be examined. In this study, we used the technique of dermal microdialysis to administer pharmacological agents singly and in combination for up to 5 hours. Muscarinic stimulation with pilocarpine nitrate (50 mug ml(-1) to 1.66 mg ml(-1)) produced a sigmoid dose response curve, with maximal sweating (measured as transepidermal water loss) (mean 70 g m(-2) hour(-1)) after 15 minutes. This was sustained at steady-state levels (55 g m(-2) hour(-1)) until perfusion stopped. Perfusion with atropine (0.003 mg ml(-1)) reduced sweating below baseline and blocked pilocarpine-induced sweating completely. Noradrenaline (0.005 mg ml(-1)) induced much lower sweat rates than pilocarpine (56.8+/-1.62 g m(-2) hour(-1) vs 8.2+/-1.2 g m(-2) hour(-1), respectively, P<0.001) and this was unaffected by co-administration of atropine. This method has made it possible to show that sweat glands are capable of sustaining near maximal activity for at least 5 hours. The method has future application in investigation of conditions with disordered sweat gland activity.

Preclinical pilot study monitoring topical drug penetration and dermal bioavailability of a peptidase inhibitor from different galenic formulations into pig dermis, using cutaneous microdialysis.

PubMed

Quist, S R; Heimburg, A; Bank, U; Mahnkopf, D; Koch, G; Gollnick, H; Täger, M; Ansorge, S

2017-08-01

Cutaneous microdialysis (CM) is an ex vivo technique that allows study of tissue chemistry, including bioavailability of actual tissue concentration of unbound drug in the interstitial fluid of the body. To test the penetration and dermal bioavailability of galenic formulations of the small-molecule IP10.C8, a dual-protease inhibitor of the dipeptidyl peptidase and aminopeptidase families. Using CM, we tested the penetration and dermal bioavailability of IP10.C8 into the dermis and subcutis of pigs, and determined the tissue concentration of IP10.C8 enzymatically, using an enzyme activity assay (substrate Gly-Pro-pNA) and high performance liquid chromatography. Dermal bioavailability was enhanced by using microemulsion or the addition of the penetration enhancer oleic acid to a hydroxyethylcellulose (HEC) gel formulation. Dermal bioavailability was also enhanced when galenic formulations were prepared with higher pH (7.5 vs. 6.5) or higher drug concentration (5% vs. 1%) in HEC gel. It seems possible, using CM for topical skin penetration testing in anaesthetized domestic pigs, to test the bioavailability of newly designed drugs. However, the experimental time is limited due to the anaesthesia, and is dependent on drug recovery. Validation of this technique for routine use is challenging, and more experiments are needed to validate this preclinical set-up. © 2017 British Association of Dermatologists.

Changes of noradrenergic activity and lipolysis in the subcutaneous abdominal adipose tissue of hypo- and hyperthyroid patients: an in vivo microdialysis study.

PubMed

Nedvidkova, Jara; Haluzik, Martin; Bartak, Vladimir; Dostalova, Ivana; Vlcek, Petr; Racek, Pavel; Taus, Michal; Behanova, Magdalena; Svacina, Stepan; Alesci, Salvatore; Pacak, Karel

2004-06-01

Thyroid function plays an important role in the regulation of overall metabolic rate and lipid metabolism. However, it is uncertain whether thyroid hormones directly affect lipolysis in adipose tissue and to what extent those changes contribute to overall metabolic phenotype. Our study was designed, using the microdialysis technique, to determine basal and isoprenaline-stimulated local lipolysis and to determine local concentrations of lipolysis-regulating catecholamines in abdominal subcutaneous adipose tissue in 12 patients with hypothyroidism, 6 patients with hyperthyroidism, and 12 healthy control subjects. Plasma norepinephrine (NE) concentrations in hypothyroid subjects were significantly higher than in the control and hyperthyroid groups. In contrast, systemic, adipose NE levels in hypothyroid patients were decreased relative to controls. Hyperthyroidism, on the other hand, resulted in four-fold higher adipose NE levels. Basal lipolysis measured by glycerol concentrations in adipose tissue was significantly attenuated in hypothyroid patients and markedly increased in hyperthyroid patients in comparison with the control group. In addition to differences in basal lipolysis, hypothyroidism resulted in attenuated, and hyperthyroidism in enhanced, lipolytic response to local stimulation with beta(1,2)-adrenergic agonist isoprenaline. These results demonstrate that lipolysis in abdominal subcutaneous adipose tissue is strongly modulated by thyroid function. We suggest that thyroid hormones regulate lipolysis primarily by affecting local NE concentration and/or adrenergic postreceptor signaling.

Optimization and evaluation of pluronic lecithin organogels as a transdermal delivery vehicle for sinomenine.

PubMed

Ba, Wenqiang; Li, Zhou; Wang, Lisheng; Wang, Ding; Liao, Weiguo; Fan, Wentao; Wu, Yinai; Liao, Fengyun; Yu, Jianye

2016-08-01

The purpose of the present study was to prepare and optimize sinomenine (SIN) pluronic lecithin organogels system (PLO), and to evaluate the permeability of the optimized PLO in vitro and in vivo. Box-Behnken design was used to optimize the PLO and the optimized formulation was pluronic F127 of 19.61%, lecithin of 3.60% and SIN of 1.27%. The formulation was evaluated its skin permeation and drug deposition both in vitro and in vivo compared with gel. Permeation and deposition studies of PLO were carried out with Franz diffusion cells in vitro and with microdialysis in vivo. In vitro studies, permeation rate (Jss) of SIN from PLO was 146.55 ± 2.93 μg/cm(2)/h, significantly higher than that of gel (120.39 μg/cm(2)/h) and the amount of SIN deposited in skin from the PLO was 10.08 ± 0.86 μg/cm(2), significantly larger than that from gel (6.01 ± 0.04 μg/cm(2)). In vivo skin microdialysis studies showed that the maximum concentration (Cmax) of SIN from PLO in "permeation study" and "drug-deposition study" were 150.27 ± 20.85 μg/ml and 67.95 μg/ml, respectively, both significantly higher than that of SIN from gel (29.66 and 6.73 μg/ml). The results recommend that PLO can be used as an advantageous transdermal delivery vehicle to enhance the permeation and skin deposition of SIN.

Effects of dimethylaminoethanol pyroglutamate (DMAE p-Glu) against memory deficits induced by scopolamine: evidence from preclinical and clinical studies.

PubMed

Blin, Olivier; Audebert, Christine; Pitel, Séverine; Kaladjian, Arthur; Casse-Perrot, Catherine; Zaim, Mohammed; Micallef, Joelle; Tisne-Versailles, Jacky; Sokoloff, Pierre; Chopin, Philippe; Marien, Marc

2009-12-01

Dimethylaminoethanol pyroglutamate (DMAE p-Glu) is a compound resulting from the reaction between dimethylaminoethanol (an indirect precursor of acetylcholine) and pyroglutamic acid (a cyclic derivative of glutamic acid having procholinergic properties and promnesic effects in both animals and man). The present study undertook preclinical and clinical evaluations to test a potential therapeutic utility for DMAE p-Glu in cognitive impairments related to central cholinergic deficit. In preclinical study, DMAE p-Glu was studied in rats by intracerebral microdialysis in conscious freely moving animals, on performance of rats in the Morris water maze test of spatial memory, and on the deficit in passive avoidance behavior induced by scopolamine. The clinical study examined the effect of DMAE p-Glu on cognitive deficits induced by an intravenous injection of scopolamine in healthy young male subjects. In rat experiments, DMAE p-Glu increased the extracellular levels of choline and acetylcholine in the medial prefrontal cortex, as assessed by intracerebral microdialysis, improved performance in a test of spatial memory, and reduced scopolamine-induced memory deficit in passive avoidance behavior. Clinical study results show that scopolamine induced a memory deficit and that DMAE p-Glu produced a significant positive effect on scores in the Buschke test, as well as a slight but significant difference on choice reaction time. These results indicate that DMAE p-Glu reduces the deleterious effect of scopolamine on long-term memory in healthy volunteers and suggest that DMAE p-Glu might be effective in reducing memory deficits in patients with cognitive impairment.

Manganese exposure alters extracellular GABA, GABA receptor and transporter protein and mRNA levels in the developing rat brain

PubMed Central

Anderson, Joel G.; Fordahl, Steve C.; Cooney, Paula T.; Weaver, Tara L.; Colyer, Christa L.; Erikson, Keith M.

2011-01-01

Unlike other essential trace elements (e.g., zinc and iron) it is the toxicity of manganese (Mn) that is more common in human populations than its deficiency. Data suggest alterations in dopamine biology may drive the effects associated with Mn neurotoxicity, though recently γ-aminobutyric acid (GABA) has been implicated. In addition, iron deficiency (ID), a common nutritional problem, may cause disturbances in neurochemistry by facilitating accumulation of Mn in the brain. Previous data from our lab have shown decreased brain tissue levels of GABA as well as decreased 3H-GABA uptake in synaptosomes as a result of Mn exposure and ID. These results indicate a possible increase in the concentration of extracellular GABA due to alterations in expression of GABA transport and receptor proteins. In this study weanling-male Sprague-Dawley rats were randomly placed into one of four dietary treatment groups: control (CN; 35 mg Fe/kg diet), iron-deficient (ID; 6 mg Fe/kg diet), CN with Mn supplementation (via the drinking water; 1 g Mn/L) (CNMn), and ID with Mn supplementation (IDMn). Using in vivo microdialysis, an increase in extracellular GABA concentrations in the striatum was observed in response to Mn exposure and ID although correlational analysis reveals that extracellular GABA is related more to extracellular iron levels and not Mn. A diverse effect of Mn exposure and ID was observed in the regions examined via Western blot and RT-PCR analysis, with effects on mRNA and protein expression of GAT-1, GABAA, and GABAB differing between and within the regions examined. For example, Mn exposure reduced GAT-1 protein expression by approximately 50% in the substantia nigra, while increasing mRNA expression approximately four-fold, while in the caudate putamen mRNA expression was decreased with no effect on protein expression. These data suggest that Mn exposure results in an increase in extracellular GABA concentrations via altered expression of transport and receptor proteins, which may be the basis of the neurological characteristics of manganism. PMID:18771689

Preparation of rotigotine-loaded microspheres and their combination use with L-DOPA to modify dyskinesias in 6-OHDA-lesioned rats.

PubMed

Wang, Aiping; Wang, Lexi; Sun, Kaoxiang; Liu, Wanhui; Sha, Chunjie; Li, Youxin

2012-09-01

To prepare rotigotine loaded microspheres (RoMS) to achieve continuous dopaminergic stimulation (CDS) for the treatment of Parkinson's disease (PD) and investigate both the therapeutic benefit and inducibility of AIMs of administration of RoMS combination with L-DOPA in 6-OHDA-leisioned rats. Rotigotine was encapsulated into poly(lactic-co-glycolic acid) (PLGA) microspheres by an oil-in-water emulsion solvent evaporation technique. In vitro characteristics and in vivo pharmacokinetics of RoMS either in rat blood or brain (by microdialysis) were investigated. Contraversive rotations and AIMs were observed to investigate the therapeutic benefit and the propensity to induce dyskinesia of RoMS or RoMS combination with L-DOPA in 6-OHDA-lesioned rats. RoMS displayed continuous-release characteristics of rotigotine in animals and exhibited a steady efficacy lasted for 2 weeks in 6-OHDA-lesioned rats. No significant difference of the therapeutic benefit between the treatment of RoMS and pulsatile L-DOPA combination and mono L-DOPA was found. While the dyskinesia was significantly decreased with the treatment of RoMS and pulsatile L-DOPA combination compared to mono L-DOPA. RoMS could supply an alternative of CDS for the treatment of PD and the study indicates a potential advantage of RoMS for the treatment of mild and advanced PD patient in combination with L-DOPA.

Pharmacological Blockade of Serotonin 5-HT7 Receptor Reverses Working Memory Deficits in Rats by Normalizing Cortical Glutamate Neurotransmission

PubMed Central

Bonaventure, Pascal; Aluisio, Leah; Shoblock, James; Boggs, Jamin D.; Fraser, Ian C.; Lord, Brian; Lovenberg, Timothy W.; Galici, Ruggero

2011-01-01

The role of 5-HT7 receptor has been demonstrated in various animal models of mood disorders; however its function in cognition remains largely speculative. This study evaluates the effects of SB-269970, a selective 5-HT7 antagonist, in a translational model of working memory deficit and investigates whether it modulates cortical glutamate and/or dopamine neurotransmission in rats. The effect of SB-269970 was evaluated in the delayed non-matching to position task alone or in combination with MK-801, a non-competitive NMDA receptor antagonist, and, in separate experiments, with scopolamine, a non-selective muscarinic antagonist. SB-269970 (10 mg/kg) significantly reversed the deficits induced by MK-801 (0.1 mg/kg) but augmented the deficit induced by scopolamine (0.06 mg/kg). The ability of SB-269970 to modulate MK-801-induced glutamate and dopamine extracellular levels was separately evaluated using biosensor technology and microdialysis in the prefrontal cortex of freely moving rats. SB-269970 normalized MK-801 -induced glutamate but not dopamine extracellular levels in the prefrontal cortex. Rat plasma and brain concentrations of MK-801 were not affected by co-administration of SB-269970, arguing for a pharmacodynamic rather than a pharmacokinetic mechanism. These results indicate that 5-HT7 receptor antagonists might reverse cognitive deficits associated with NMDA receptor hypofunction by selectively normalizing glutamatergic neurotransmission. PMID:21701689

MK-801-induced behavioural sensitisation alters dopamine release and turnover in rat prefrontal cortex.

PubMed

Cui, Xiaoying; Lefevre, Emilia; Turner, Karly M; Coelho, Carlos M; Alexander, Suzy; Burne, Thomas H J; Eyles, Darryl W

2015-02-01

Repeated exposure to psychostimulants that either increase dopamine (DA) release or target N-methyl-D-aspartate (NMDA) receptors can induce behavioural sensitisation, a phenomenon that may be important for the processes of addiction and even psychosis. A critical component of behavioural sensitisation is an increase in DA release within mesocorticolimbic circuits. In particular, sensitisation to amphetamine leads to increased DA release within well-known sub-cortical brain regions and also regulatory regions such as prefrontal cortex (PFC). However, it is unknown how DA release within the PFC of animals is altered by sensitisation to NMDA receptor antagonists. The aims of the present study were twofold, firstly to examine whether a single dose of dizocilpine maleate (MK-801) could induce long-term behavioural sensitisation and secondly to examine DA release in the PFC of sensitised rats. Behavioural sensitisation was assessed by measuring locomotion after drug exposure. DA release in the PFC was measured using freely moving microdialysis. We show that a single dose of MK-801 can induce sensitisation to subsequent MK-801 exposure in a high percentage of rats (66 %). Furthermore, rats sensitised to MK-801 have altered DA release and turnover in the PFC compared with non-sensitised rats. Schizophrenia patients have been postulated to have 'endogenous sensitisation' to psychostimulants. MK-801-induced sensitised rats, in particular when compared with non-sensitised rats, provide a useful model for studying PFC dysfunction in schizophrenia.

Infusion of fluoxetine, a serotonin reuptake inhibitor, in the shell region of the nucleus accumbens increases blood glucose concentrations in rats.

PubMed

Diepenbroek, C; Rijnsburger, M; Eggels, L; van Megen, K M; Ackermans, M T; Fliers, E; Kalsbeek, A; Serlie, M J; la Fleur, S E

2017-01-10

The brain is well known to regulate blood glucose, and the hypothalamus and hindbrain, in particular, have been studied extensively to understand the underlying mechanisms. Nuclei in these regions respond to alterations in blood glucose concentrations and can alter glucose liver output or glucose tissue uptake to maintain blood glucose concentrations within strict boundaries. Interestingly, several cortico-limbic regions also respond to alterations in glucose concentrations and have been shown to project to hypothalamic nuclei and glucoregulatory organs. For instance, electrical stimulation of the shell of the nucleus accumbens (sNAc) results in increased circulating concentrations of glucose and glucagon and activation of the lateral hypothalamus (LH). Whether this is caused by the simultaneous increase in serotonin release in the sNAc remains to be determined. To study the effect of sNAc serotonin on systemic glucose metabolism, we implanted bilateral microdialysis probes in the sNAc of male Wistar rats and infused fluoxetine, a serotonin reuptake inhibitor, or vehicle after which blood glucose, endogenous glucose production (EGP) and glucoregulatory hormones were measured. Fluoxetine in the sNAc for 1h significantly increased blood glucose concentrations without an effect on glucoregulatory hormones. This increase was accompanied by a higher EGP in the fluoxetine infused rats compared to the controls. These data provide further evidence for a role of sNAc-serotonin in the regulation of glucose metabolism. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Amphetamine regulation of mesolimbic dopamine/cholecystokinin neurotransmission.

PubMed

Hurd, Y L; Lindefors, N; Brodin, E; Brené, S; Persson, H; Ungerstedt, U; Hökfelt, T

1992-04-24

The effects of acute and repeated amphetamine administration on mesolimbic dopamine (DA) neurons was assessed by studying DA and cholecystokinin (CCK) release in the nucleus accumbens (Acc), as well as effects on mRNA genes regulating DA and CCK synthesis in ventral tegmental area (VTA) cells in rats. Amphetamine (1.5 mg/kg) markedly increased extracellular levels of DA in the medial Acc (assessed by in vivo microdialysis) in drug-naive animals, about twice the amount released in animals repeatedly administered the drug for the previous 7 days (twice daily). CCK overflow was found to mirror the DA responses in that the very transient elevation of CCK monitored in drug-naive animals was attenuated in those with prior amphetamine use. The attenuation of both DA and CCK overflow in the medial Acc was found to be associated with a decrease in the number of CCK mRNA-positive VTA neurons (assessed by in situ hybridization histochemistry). Although the number of cells expressing CCK mRNA were decreased, the gene expression in those positive CCK and tyrosine hydroxylase mRNA cells in the VTA was significantly increased. The CCK mRNA neurons in the VTA were positively identified as those projecting to the medial Acc by the local perfusion of Fluoro-gold retrograde tracer via microdialysis probes located in the Acc.

Integration of Microchip Electrophoresis with Electrochemical Detection Using an Epoxy-Based Molding Method to Embed Multiple Electrode Materials

PubMed Central

Johnson, Alicia S.; Selimovic, Asmira; Martin, R. Scott

2012-01-01

This paper describes the use of epoxy-encapsulated electrodes to integrate microchip-based electrophoresis with electrochemical detection. Devices with various electrode combinations can easily be developed. This includes a palladium decoupler with a downstream working electrode material of either gold, mercury/gold, platinum, glassy carbon, or a carbon fiber bundle. Additional device components such as the platinum wires for the electrophoresis separation and the counter electrode for detection can also be integrated into the epoxy base. The effect of the decoupler configuration was studied in terms of the separation performance, detector noise, and the ability to analyze samples of a high ionic strength. The ability of both glassy carbon and carbon fiber bundle electrodes to analyze a complex mixture was demonstrated. It was also shown that a PDMS-based valving microchip can be used along with the epoxy embedded electrodes to integrate microdialysis sampling with microchip electrophoresis and electrochemical detection, with the microdialysis tubing also being embedded in the epoxy substrate. This approach enables one to vary the detection electrode material as desired in a manner where the electrodes can be polished and modified in a similar fashion to electrochemical flow cells used in liquid chromatography. PMID:22038707

In vivo release of non-neuronal acetylcholine from the human skin as measured by dermal microdialysis: effect of botulinum toxin

PubMed Central

Schlereth, Tanja; Birklein, Frank; Haack, Katrin an; Schiffmann, Susanne; Kilbinger, Heinz; Kirkpatrick, Charles James; Wessler, Ignaz

2005-01-01

Acetylcholine is synthesized in the majority of non-neuronal cells, for example in human skin. In the present experiments, the in vivo release of acetylcholine was measured by dermal microdialysis. Two microdialysis membranes were inserted intradermally at the medial shank of volunteers. Physiological saline containing 1 μM neostigmine was perfused at a constant rate of 4 μl min−1 and the effluent was collected in six subsequent 20 min periods. Acetylcholine was measured by high-pressure liquid chromatography (HPLC) combined with bioreactors and electrochemical detection. Analysis of the effluent by HPLC showed an acetylcholine peak that disappeared, when the analytical column was packed with acetylcholine-specific esterase, confirming the presence of acetylcholine. In the absence of neostigmine, 71±51 pmol acetylcholine (n=4) was found during a 120 min period. The amount increased to 183±43 pmol (n=34), when the perfusion medium contained 1 μM neostigmine. Injection of 100 MU botulinum toxin subcutaneously blocked sweating completely, but the release of acetylcholine was not affected (botulinum toxin treated skin: 116±70 pmol acetylcholine/120 min; untreated skin: 50±20 pmol; n=4). Quinine (1 mM), inhibitor of organic cation transporters, and carnitine (0.1 mM), substrate of the Na+-dependent carnitine transporter OCTN2, tended to reduce acetylcholine release (by 40%, not significant). Our experiments demonstrate, for the first time, the in vivo release of non-neuronal acetylcholine in human skin. Organic cation transporters are not predominantly involved in the release of non-neuronal acetylcholine from the human skin. PMID:16273117

In vivo continuous glucose monitoring using a chip based near infrared sensor

NASA Astrophysics Data System (ADS)

Ben Mohammadi, L.; Sigloch, S.; Frese, I.; Welzel, K.; Göddel, M.; Klotzbücher, T.

2014-05-01

Diabetes is a serious health condition considered to be one of the major healthcare epidemics of modern era. An effective treatment of this disease can be only achieved by reliable continuous information on blood glucose levels. In this work we present a minimally invasive, chip-based near infrared (NIR) sensor, combined with microdialysis, for continuous glucose monitoring (CGM). The sensor principle is based on difference absorption spectroscopy in the 1st overtone band of the near infrared spectrum. The device features a multi-emitter LED and InGaAs-Photodiodes, which are located on a single electronic board (non-disposable part), connected to a personal computer via Bluetooth. The disposable part consists of a chip containing the fluidic connections for microdialysis, two fluidic channels acting as optical transmission cells and total internally reflecting mirrors for in- and out-coupling of the LED light to the chip and to the detectors. The sensor is combined with an intraveneous microdialysis to separate the glucose from the cells and proteins in the blood and operates without any chemical consumption. In vitro measurements showed a linear relationship between glucose concentration and the integrated difference signal with a coefficient of determination of 99 % in the relevant physiological concentration range from 0 to 400 mg/dl. In vivo measurements on 10 patients showed that the NIR-CGM sensor data reflects the blood reference values adequately, if a proper calibration and signal drift compensation is applied. The MARE (mean absolute relative error) value taken over all patient data is 13.8 %. The best achieved MARE value is at 4.8 %, whereas the worst is 25.8 %, with a standard deviation of 5.5 %.

Carbon dioxide, oxygen, and pH detection in animal adipose tissue by means of extracorporeal microdialysis

NASA Astrophysics Data System (ADS)

Baldini, F.; Bizzarri, A.; Cajlakovic, M.; Feichtner, F.; Gianesello, L.; Giannetti, A.; Gori, G.; Konrad, C.; Mencaglia, A. A.; Mori, E.; Pavoni, V.; Perna, A. M.; Trono, C.

2007-05-01

Atypical physiological symptoms can be developed in healthy people under critically ill conditions. pH, pO II and pCO II are informative indicators of the conditions of a living system and can be valuable in determining the physiologic status of the critically ill patients. The continuous monitoring of these small molecules into the interstitial fluid (ISF) is a promising approach to reduce diagnostic blood loss and painful stress associated with blood sampling. Microdialysis is the approach followed for the extraction of the sample from the subcutaneous adipose tissue; the drawn interstitial fluid flows through a microfluidic circuit formed by the microdialysis catheter in series with a glass capillary on the internal wall of which the appropriate chemistry for sensing is immobilised. Absorption changes for pH sensor and modulation of the fluorescence lifetime for pO II and pCO II are the working principle. Phenol red covalently bound into the internal wall of a glass capillary by means of the Mannich reaction and platinum(II) tetrakis-pentafluorophenyl-porphyrine entrapped within a polymerised polystyrene layer are the chemical transducers used for pH and oxygen detection; the ion pair 8- hydroxypyrene-1,3,6-trisulfonic acid trisodium salt/ tetraoctylammonium hydroxide, dissolved in a silicon-based polymeric matrix, is used for the carbon dioxide detection. A suitable hemorrhagic shock model was developed in order to validate clinically the developed sensors in the condition of extreme stress and the obtained results show that the adipose tissue can become an alternative site for the continuous oitoring of pH, pO II and pCO II.

Doxorubicin-loaded Zein in situ gel for interstitial chemotherapy.

PubMed

Cao, Xiaoying; Geng, Jianning; Su, Suwen; Zhang, Linan; Xu, Qian; Zhang, Li; Xie, Yinghua; Wu, Shaomei; Sun, Yongjun; Gao, Zibin

2012-01-01

A novel drug delivery system of doxorubicin (DOX)-loaded Zein in situ gel for interstitial chemotherapy was investigated in this study. The possible mechanisms of drug release were described according to morphological analysis by optical microscopy and scanning electronic microscope (SEM). In vitro and in vivo anti-tumor activity studies showed that DOX-loaded Zein in situ gel was superior to DOX solution. Local pharmacokinetics in tumor tissue was studied by quantitative analysis with confocal laser scanning microscopy (CLSM) combined with microdialysis technology. A pharmacokinetics mathematical model of DOX-loaded Zein in situ gel in tumors was then built.

Cerebral taurine release mechanisms in vivo: pharmacological investigations in rats using microdialysis for proof of principle.

PubMed

Scheller, D; Korte, M; Szathmary, S; Tegtmeier, F

2000-06-01

Cerebral taurine acts as neurotransmitter, as neuromodulator, or as osmoregulator. To investigate its release mechanisms in vivo, we combined the microdialysis technique with a variety of experimental paradigms. Taurine release was stimulated by either NMDA, NO or a hypotonic solution locally with or without the addition of the NMDA antagonists APV or Ketamine, or the NO synthase inhibitor L-NAME. Alternatively, the neuroprotective drug lubeluzole was applied i.v. NMDA, NO or the hypotonic solution stimulated the release of taurine. NMDA-mediated taurine release was inhibited by either APV, Ketamine or the NO synthase inhibitor L-NAME. Lubeluzole had no effect. Under the hypotonic conditions only lubeluzole was effective. These data confirm in vivo that the NMDA-induced taurine release is mediated via the NO cascade. By contrast, the release after a hypotonic stimulus is not related to the NO cascade. Instead, Na(+)- and/or Ca(2+)-mediated events might have been attenuated by lubeluzole.

Inhibition of neuropeptide degradation suppresses sweating but increases the area of the axon reflex flare.

PubMed

Schlereth, Tanja; Breimhorst, Markus; Werner, Nicolas; Pottschmidt, Katrin; Drummond, Peter D; Birklein, Frank

2013-04-01

The neuropeptides CGRP (calcitonin gene-elated peptide) and substance P (SP) mediate neurogenic inflammation. Both are degraded by the neutral endopeptidase (NEP) which can be blocked by phosphoramidon. The aim was to evaluate the effect of NEP inhibition on sweating and vasodilatation. Dermal microdialysis was performed on the skin of 39 subjects. Two fibres were perfused with phosphoramidon (0.01%, 0.02% or 0.2%), two with saline. Acetylcholine (ACh) was either added to the microdialysis perfusate (n = 30, 10(-2)  m) or thermoregulatory sweating was induced (n = 9). Co-application of phosphoramidon reduced cholinergic and thermoregulatory sweating. However, the flare size - a localized increase in superficial blood flow after ACh-application - was significantly increased. The increase in flare size is most probably due to increased CGRP levels. The inhibition of sweating by phosphoramidon may involve an increase in SP, a reduction in CGRP-degradation fragments or a direct inhibitory action of phosphoramidon. © 2013 John Wiley & Sons A/S.

Recognition unit-free and self-cleaning photoelectrochemical sensing platform on TiO2 nanotube photonic crystals for sensitive and selective detection of dopamine release from mouse brain.

PubMed

Xin, Yanmei; Li, Zhenzhen; Wu, Wenlong; Fu, Baihe; Wu, Hongjun; Zhang, Zhonghai

2017-01-15

For implementing sensitive and selective detection of biological molecules, the biosensors are been designed more and more complicated. The exploration of detection platform in a simple way without loss their sensitivity and selectivity is always a big challenge. Herein, a prototype of recognition biomolecule unit-free photoelectrochemical (PEC) sensing platform with self-cleaning activity is proposed with TiO 2 nanotube photonic crystal (TiO 2 NTPCs) materials as photoelectrode, and dopamine (DA) molecule as both sensitizer and target analyte. The unique adsorption between DA and TiO 2 NTPCs induces the formation of charge transfer complex, which not only expends the optical absorption of TiO 2 into visible light region, thus significantly boosts the PEC performance under illumination of visible light, but also implements the selective detection of DA on TiO 2 photoelectrode. This simple but efficient PEC analysis platform presents a low detection limit of 0.15nm for detection of DA, which allows to realize the sensitive and selective determination of DA release from the mouse brain for its practical application after coupled with a microdialysis probe. The DA functionalized TiO 2 NTPCs PEC sensing platform opens up a new PEC detection model, without using extra-biomolecule auxiliary, just with target molecule naturally adsorbed on the electrode for sensitive and selective detection, and paves a new avenue for biosensors design with minimalism idea. Copyright © 2016 Elsevier B.V. All rights reserved.

Rivastigmine improves isolation rearing-induced prepulse inhibition deficits via muscarinic acetylcholine receptors in mice.

PubMed

Higashino, Kosuke; Ago, Yukio; Umeki, Takahiro; Hasebe, Shigeru; Onaka, Yusuke; Hashimoto, Hitoshi; Takuma, Kazuhiro; Matsuda, Toshio

2016-02-01

The acetylcholinesterase inhibitors donepezil, galantamine, and rivastigmine are used for the treatment of Alzheimer's disease. We previously demonstrated that donepezil and galantamine differentially affect isolation rearing-induced prepulse inhibition (PPI) deficits and that this might be due to differential effects on brain muscarinic acetylcholine (mACh) receptor function in mice. We examined the effects of rivastigmine on isolation rearing-induced PPI deficits, brain ACh levels, and mACh receptor function in mice. Acoustic startle responses were measured in a startle chamber. Microdialysis was performed, and the levels of dopamine and ACh in the prefrontal cortex were measured. Rivastigmine (0.3 mg/kg) improved PPI deficits, and this improvement was antagonized by the mACh receptor antagonist telenzepine but not by the nicotinic ACh receptor antagonist mecamylamine. Rivastigmine increased extracellular ACh levels by approximately 2-3-fold, less than the increase produced by galantamine. Rivastigmine enhanced the effect of the mACh receptor agonist N-desmethylclozapine on prefrontal dopamine release, a marker of mACh receptor function, and this increase was blocked by telenzepine. In contrast, galantamine did not affect N-desmethylclozapine-induced dopamine release. Furthermore, rivastigmine did not affect cortical dopamine release induced by the serotonin1A receptor agonist osemozotan, suggesting that the effect of rivastigmine has specificity for mACh receptors. Taken together with our previous finding that marked increases in ACh levels are required for the PPI deficit improvement induced by galantamine, our present results suggest that rivastigmine improves isolation rearing-induced PPI deficits by increasing ACh levels and by concomitantly enhancing mACh receptor function.

Preclinical examination of clofarabine in pediatric ependymoma: intratumoral concentrations insufficient to warrant further study.

PubMed

Patel, Yogesh T; Jacus, Megan O; Boulos, Nidal; Dapper, Jason D; Davis, Abigail D; Vuppala, Pradeep K; Freeman, Burgess B; Mohankumar, Kumarasamypet M; Throm, Stacy L; Gilbertson, Richard J; Stewart, Clinton F

2015-05-01

Clofarabine, a deoxyadenosine analog, was an active anticancer drug in our in vitro high-throughput screening against mouse ependymoma neurospheres. To characterize the clofarabine disposition in mice for further preclinical efficacy studies, we evaluated the plasma and central nervous system disposition in a mouse model of ependymoma. A plasma pharmacokinetic study of clofarabine (45 mg/kg, IP) was performed in CD1 nude mice bearing ependymoma to obtain initial plasma pharmacokinetic parameters. These estimates were used to derive D-optimal plasma sampling time points for cerebral microdialysis studies. A simulation of clofarabine pharmacokinetics in mice and pediatric patients suggested that a dosage of 30 mg/kg IP in mice would give exposures comparable to that in children at a dosage of 148 mg/m(2). Cerebral microdialysis was performed to study the tumor extracellular fluid (ECF) disposition of clofarabine (30 mg/kg, IP) in the ependymoma cortical allografts. Plasma and tumor ECF concentration-time data were analyzed using a nonlinear mixed effects modeling approach. The median unbound fraction of clofarabine in mouse plasma was 0.79. The unbound tumor to plasma partition coefficient (K pt,uu: ratio of tumor to plasma AUCu,0-inf) of clofarabine was 0.12 ± 0.05. The model-predicted mean tumor ECF clofarabine concentrations were below the in vitro 1-h IC50 (407 ng/mL) for ependymoma neurospheres. Thus, our results show the clofarabine exposure reached in the tumor ECF was below that associated with an antitumor effect in our in vitro washout study. Therefore, clofarabine was de-prioritized as an agent to treat ependymoma, and further preclinical studies were not pursued.

Preclinical examination of clofarabine in pediatric ependymoma: Intratumoral concentrations insufficient to warrant further study

PubMed Central

Patel, Yogesh T.; Jacus, Megan O.; Boulos, Nidal; Dapper, Jason D.; Davis, Abigail D.; Vuppala, Pradeep K.; Freeman, Burgess B.; Mohankumar, Kumarasamypet M.; Throm, Stacy L.; Gilbertson, Richard J.; Stewart, Clinton F.

2015-01-01

Clofarabine, a deoxyadenosine analog, was an active anticancer drug in our in vitro high-throughput screening against mouse ependymoma neurospheres. To characterize the clofarabine disposition in mice for further preclinical efficacy studies, we evaluated the plasma and central nervous system (CNS) disposition in a mouse model of ependymoma. A plasma pharmacokinetic study of clofarabine (45 mg/kg, IP) was performed in CD1 nude mice bearing ependymoma to obtain initial plasma pharmacokinetic parameters. These estimates were used to derive D-optimal plasma sampling time-points for cerebral microdialysis studies. A simulation of clofarabine pharmacokinetics in mice and pediatric patients suggested that a dosage of 30 mg/kg, IP in mice would give exposures comparable to that in children at a dosage of 148 mg/m2. Cerebral microdialysis was performed to study the tumor extracellular fluid (ECF) disposition of clofarabine (30 mg/kg, IP) in the ependymoma cortical allografts. Plasma and tumor ECF concentration-time data were analyzed using a nonlinear mixed effects modeling approach. The median unbound fraction of clofarabine in mouse plasma was 0.79. The unbound tumor to plasma partition coefficient (Kpt,uu: ratio of tumor to plasma AUCu,0-inf) of clofarabine was 0.12±0.05. The model predicted mean tumor ECF clofarabine concentrations were below the in vitro 1-hr IC50 (407 ng/mL) for ependymoma neurospheres. Thus, our results show the clofarabine exposure reached in the tumor ECF was below that associated with an antitumor effect in our in vitro washout study. Therefore, clofarabine was de-prioritized as an agent to treat ependymoma, and further preclinical studies were not pursued. PMID:25724157

A New Drug Design Targeting the Adenosinergic System for Huntington's Disease

PubMed Central

Lin, Jiun-Tsai; Lin, Chia-I; Liu, Eric Minwei; Lin, Chun-Jung; Chen, Wan-Ping; Shen, Yuh-Chiang; Chen, Hui-Mei; Chen, Jhih-Bin; Lai, Hsing-Lin; Yang, Chieh-Wen; Chiang, Ming-Chang; Wu, Yu-Shuo; Chang, Chen; Chen, Jiang-Fan; Fang, Jim-Min; Lin, Yun-Lian; Chern, Yijuang

2011-01-01

Background Huntington's disease (HD) is a neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The expanded CAG repeats are translated into polyglutamine (polyQ), causing aberrant functions as well as aggregate formation of mutant Htt. Effective treatments for HD are yet to be developed. Methodology/Principal Findings Here, we report a novel dual-function compound, N 6-(4-hydroxybenzyl)adenine riboside (designated T1-11) which activates the A2AR and a major adenosine transporter (ENT1). T1-11 was originally isolated from a Chinese medicinal herb. Molecular modeling analyses showed that T1-11 binds to the adenosine pockets of the A2AR and ENT1. Introduction of T1-11 into the striatum significantly enhanced the level of striatal adenosine as determined by a microdialysis technique, demonstrating that T1-11 inhibited adenosine uptake in vivo. A single intraperitoneal injection of T1-11 in wildtype mice, but not in A2AR knockout mice, increased cAMP level in the brain. Thus, T1-11 enters the brain and elevates cAMP via activation of the A2AR in vivo. Most importantly, addition of T1-11 (0.05 mg/ml) to the drinking water of a transgenic mouse model of HD (R6/2) ameliorated the progressive deterioration in motor coordination, reduced the formation of striatal Htt aggregates, elevated proteasome activity, and increased the level of an important neurotrophic factor (brain derived neurotrophic factor) in the brain. These results demonstrate the therapeutic potential of T1-11 for treating HD. Conclusions/Significance The dual functions of T1-11 enable T1-11 to effectively activate the adenosinergic system and subsequently delay the progression of HD. This is a novel therapeutic strategy for HD. Similar dual-function drugs aimed at a particular neurotransmitter system as proposed herein may be applicable to other neurotransmitter systems (e.g., the dopamine receptor/dopamine transporter and the serotonin receptor/serotonin transporter) and may facilitate the development of new drugs for other neurodegenerative diseases. PMID:21713039

Effects of microdialyzed oxotremorine, carbachol, epibatidine, and scopolamine on intraspinal release of acetylcholine in the rat.

PubMed

Höglund, A U; Hamilton, C; Lindblom, L

2000-10-01

Intrathecally administered cholinergic agonists such as oxotremorine (muscarinic), carbachol (mixed nicotinic and muscarinic agonist), and epibatidine (nicotinic) have all been shown to reduce nociception in behavioral studies. Thus, there is substantial evidence for a role of acetylcholine (ACh) in the control of nociception in the spinal cord, but the mechanisms regulating ACh release are not known. The present study was initiated to establish a rat model to study which mechanisms are involved in the control of ACh release. Spinal microdialysis probes were inserted intraspinally at the C1-C5 spinal level in isoflurane-anesthetized rats. The probes were perfused with Ringer's solution containing 10 microM neostigmine to prevent degradation of ACh. Oxotremorine, carbachol, epibatidine, and scopolamine, dissolved in Ringer's solution, were administered intraspinally via dialysis and 30 microliter/10-min samples of dialysate were collected for HPLC analysis of ACh content. The release of ACh was found to be constant in the control (Ringer's only) situation during the experimental period of 150 min. Oxotremorine (100-1000 microM), carbachol (1 mM), and epibatidine (50-5000 microM) enhanced but scopolamine (50-200 nM) decreased the intraspinal release of ACh. Oxotremorine (ED(50) = 118 microM) and epibatidine (ED(50) = 175 microM) were found to produce a dose-dependent increase of ACh release. Cholinergic agonists caused an increase of intraspinal ACh and the antagonist scopolamine caused a decreased release of ACh. The data do not support an autoreceptor function of either nicotinic or muscarinic receptors in the spinal cord, contrary to what has been observed in the brain.

Subchronic nandrolone administration reduces cocaine-induced dopamine and 5-hydroxytryptamine outflow in the rat nucleus accumbens.

PubMed

Kurling-Kailanto, Sanna; Kankaanpää, Aino; Seppälä, Timo

2010-04-01

The abuse of anabolic androgenic steroids (AASs) is not only a problem in the world of sports but is associated with the polydrug use of nonathletes. Investigations of the neurochemical effects of AAS have focused in part on the monoaminergic systems, involving, among other things, the development of dependence. We have previously shown that pretreatment with nandrolone decanoate attenuates dose-dependently the increase in extracellular dopamine (DA) concentration evoked by amphetamine and 3,4-methylenedioyxymethamphetamine in the nucleus accumbens (NAc). The aim of this study was to investigate whether the nandrolone pre-exposure modulates the acute neurochemical and behavioral effects of cocaine in rats and whether the effects are long lasting. DA, 5-hydroxytryptamine (5-HT), and their metabolites were measured from samples collected from the NAc by microdialysis. The behavior of the animals was recorded. The present study demonstrates that five injections of nandrolone (5 and 20 mg/kg) inhibited cocaine-evoked DA and 5-HT outflow in the NAc, locomotor activity (LMA), and stereotyped behavior in experimental animals, and that these effects are seen even after elimination of nandrolone from bloodstream. Given that accumbal outflow of DA and 5-HT, as well as LMA and stereotyped behavior, is related to gratification of stimulant drugs, this study suggests that nandrolone, at the doses tested, has a significant effect on the pleasurable properties of cocaine. Furthermore, because neurochemical and behavioral responses were still attenuated after a fairly long recovery period, it seems that nandrolone may induce long-lasting changes in the brains of rat.

Microdialysis of glucose in subcutaneous adipose tissue up to 3 weeks in healthy volunteers.

PubMed

Wientjes, K J; Vonk, P; Vonk-van Klei, Y; Schoonen, A J; Kossen, N W

1998-09-01

To measure possible changes in dialysate glucose concentrations over time, to validate the diffusional model for glucose transport from tissue to the probe, and to evaluate the actual glucose concentration in adipose tissue. Glucose concentrations in the subcutaneous adipose tissue of five healthy subjects (age 25 +/- 2.7 years, BMI 23.2 +/- 2.3 kg/m2 [mean +/- SD]) were measured by the microdialysis technique and compared with blood glucose. We applied microdialysis probes with hollow fibers of various membrane length (10-35 mm), used eight perfusion flow rates (0.5-20 microl/min), and perfused four glucose solutions (0.0, 2.8, 8.3, 11.1 mmol/l). After implantation, a substantial decrease in glucose recovery to the lowest value of 26 +/- 10% of the final plateau value was noted during the first few hours (n = 4). Recovery increased and stabilized after 5-9 days at 84.0 +/- 7.4% of capillary blood glucose when a flow rate of 0.5 microl/min was applied. According to the zero net-flux method, the glucose concentration in equilibrium, Cequi, with the surrounding tissue can be obtained. This concentration also decreases; however, 1 h after recovery, Cequi increases again over 1 or 2 days to a stable value that is not significantly different from the measured capillary blood glucose (P < 0.05). Using various perfusion flow rates and probes (membrane length 10-35 mm), it is shown that diffusion is the rate-limiting process for glucose transport through tissue. Insertion of the microdialysis probes causes damage to the adipose cells and the vascular bed around the probe. Glucose recovery decreases because of a lower blood supply. In 5-9 days, glucose recovery increases; apparently, this time is needed to repair the microstructure of tissue around the probe. After stabilization of the recovery, no loss of probe permeability, which is due to biocompatibility problems, was seen. The change during the 2 days in equilibrium concentration is probably caused by an inflammation reaction that consumes glucose around the probe. The individual increase in recovery during the 1st days after probe insertion until a stable plateau value is reached (flow rate >0 microl/min) is complicated for short-term clinical glucose measurements in adipose tissue. After stabilization, the mean equilibrium concentration of all subjects was equal to the mean capillary blood glucose concentration. Therefore, we conclude that capillary blood glucose concentration probably is the driving force for diffusion through the capillary wall into the probe and is not some interstitial concentration.

Effects of the neurotoxin MPTP and pargyline protection on extracellular energy metabolites and dopamine levels in the striatum of freely moving rats.

PubMed

Bazzu, Gianfranco; Rocchitta, Gaia; Migheli, Rossana; Alvau, Maria Domenica; Zinellu, Manuel; Puggioni, Giulia; Calia, Giammario; Mercanti, Giulia; Giusti, Pietro; Desole, Maria Speranza; Serra, Pier Andrea

2013-11-13

The neurotoxin MPTP is known to induce dopamine release and depletion of ATP in the striatum of rats. Therefore, we studied the changes induced by MPTP and pargyline protection both on striatal dopamine release and on extracellular energy metabolites in freely moving rats, using dual asymmetric-flow microdialysis. A dual microdialysis probe was inserted in the right striatum of rats. MPTP (25mg/kg, 15mg/kg, 10mg/kg) was intraperitoneally administered for three consecutive days. MAO-B inhibitor pargyline (15mg/kg) was systemically administered before neurotoxin administration. The first MPTP dose induced an increase in dialysate dopamine and a decrease of DOPAC levels in striatal dialysate. After the first neurotoxin administration, increases in striatal glucose, lactate, pyruvate, lactate/pyruvate (L/P) and lactate/glucose (L/G) ratios were observed. Subsequent MPTP administrations showed a progressive reduction of dopamine, glucose and pyruvate levels with a concomitant further increase in lactate levels and L/P and L/G ratios. At day 1, pargyline pre-treatment attenuated the MPTP-induced changes in all studied analytes. Starting from day 2, pargyline prevented the depletion of dopamine, glucose and pyruvate while reduced the increase of lactate, L/P ratio and L/G ratio. These in vivo results suggest a pargyline neuroprotection role against the MPTP-induced energetic impairment consequent to mitochondrial damage. This neuroprotective effect was confirmed by TH immunostaining of the substantia nigra. © 2013 Elsevier B.V. All rights reserved.

Forced swimming-induced oxytocin release into blood and brain: Effects of adrenalectomy and corticosterone treatment.

PubMed

Torner, Luz; Plotsky, Paul M; Neumann, Inga D; de Jong, Trynke R

2017-03-01

The oxytocin (OXT) system is functionally linked to the HPA axis in a reciprocal and complex manner. Certain stressors are known to cause the simultaneous release of OXT and adrenocorticotrophic hormone (ACTH) followed by corticosterone (CORT). Furthermore, brain OXT attenuates ACTH and CORT responses. Although there are some indications of CORT influencing OXT neurotransmission, specific effects of CORT on neurohypophyseal or intra-hypothalamic release of OXT have not been studied in detail. In the present set of experiments, adult male rats were adrenalectomized (ADX) or sham-operated and fitted with a jugular vein catheter and/or microdialysis probe targeting the hypothalamic paraventricular nucleus (PVN). Blood samples and dialysates were collected before and after forced swimming (FS) and analyzed for CORT, ACTH and AVP concentrations (in plasma) and OXT concentrations (in plasma and dialysates). Experimental treatments included acute infusion of CORT (70 or 175μg/kg i.v.) 5min prior to FS, or subcutaneous placement of 40% CORT pellets resulting in stable CORT levels in the normal basal range. Although ADX did not alter basal OXT concentrations either in plasma or in microdialysates from the PVN, it did cause an exaggerated peripheral secretion of OXT and a blunted intra-PVN release of OXT in response to FS. CORT pellets did not influence either of these ADX-induced effects, while acute infusion of 175μg/kg CORT rescued the stress-induced rise in OXT release within the PVN and modestly increased peripheral OXT secretion. In conclusion, these results indicate that CORT regulates both peripheral and intracerebral OXT release, but in an independent manner. Whereas the peripheral secretion of OXT occurs simultaneously to HPA axis activation in response to FS and is modestly influenced by CORT, HPA axis activation and circulating CORT strongly contribute to the stress-induced stimulation of OXT release within the PVN. Copyright © 2016 Elsevier Ltd. All rights reserved.

Neurotoxic Effects of 5-MeO-DIPT: A Psychoactive Tryptamine Derivative in Rats.

PubMed

Noworyta-Sokołowska, Karolina; Kamińska, Katarzyna; Kreiner, Grzegorz; Rogóż, Zofia; Gołembiowska, Krystyna

2016-11-01

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT, 'foxy') is one of the most popular tryptamine hallucinogens in the illicit drug market. It produces serious adverse effects, but its pharmacological profile is not well recognized. In vitro data have shown that 5-MeO-DIPT acts as a potent serotonin transporter (SERT) inhibitor and displays high affinity at serotonin 5-HT1A, 5-HT2A, and 5-HT2C receptors. In this study, using microdialysis in freely moving rats, we examined the effect of 5-MeO-DIPT on dopamine (DA), serotonin (5-HT), and glutamate release in the rat striatum, nucleus accumbens, and frontal cortex. In search of a possible neurotoxic effect of 5-MeO-DIPT, we measured DA and 5-HT tissue content in the above rat brain regions and also determined the oxidative DNA damage with the comet assay. Moreover, we tested drug-elicited head-twitch response and a forepaw treading induced by 8-OH-DPAT. 5-MeO-DIPT at doses of 5, 10, and 20 mg/kg increased extracellular DA, 5-HT, and glutamate level but the differences in the potency were found between brain regions. 5-MeO-DIPT increased 5-HT and decreased 5-HIAA tissue content which seems to result from SERT inhibition. On the other hand, a decrease in DA, DOPAC, and HVA tissue contents suggests possible adaptive changes in DA turnover or damage of DA terminals by 5-MeO-DIPT. DNA single and double-strand breaks persisted up to 60 days after the treatment, indicating marked neurotoxicity of 5-MeO-DIPT. The induction of head-twitch response and potentiation of forepaw treading induced by 8-OH-DPAT indicate that hallucinogenic activity seems to be mediated through the stimulation of 5-HT2A and 5-HT1A receptors by 5-MeO-DIPT.

Pharmacological Characterization of H05, a Novel Serotonin and Noradrenaline Reuptake Inhibitor with Moderate 5-HT2A Antagonist Activity for the Treatment of Depression.

PubMed

Xu, Xiangqing; Wei, Yaqin; Guo, Qiang; Zhao, Song; Liu, Zhiqiang; Xiao, Ting; Liu, Yani; Qiu, Yinli; Hou, Yuanyuan; Zhang, Guisen; Wang, KeWei

2018-06-01

Multitarget antidepressants selectively inhibiting monoaminergic transporters and 5-hydroxytryptamine (5-HT) 2A receptor have demonstrated higher efficacy and fewer side effects than selective serotonin reuptake inhibitors. In the present study, we synthesized a series of novel 3-(benzo[d][1,3]dioxol-4-yloxy)-3-arylpropyl amine derivatives, among which compound H05 was identified as a lead, exhibiting potent inhibitory effects on both serotonin ( K i = 4.81 nM) and norepinephrine (NE) ( K i = 6.72 nM) transporters and moderate 5-HT 2A antagonist activity (IC 50 = 60.37 nM). H05 was able to dose-dependently reduce the immobility duration in mouse forced swimming test and tail suspension test, with the minimal effective doses lower than those of duloxetine, and showed no stimulatory effect on locomotor activity. The administration of H05 (5, 10, and 20 mg/kg, by mouth) significantly shortened the immobility time of adrenocorticotropin-treated rats that serve as a model of treatment-resistant depression, whereas imipramine (30 mg/kg, by mouth) and duloxetine (30 mg/kg, by mouth) showed no obvious effects. Chronic treatment with H05 reversed the depressive-like behaviors in a rat model of chronic unpredictable mild stress and a mouse model of corticosterone-induced depression. Microdialysis analysis revealed that the administration of H05 at either 10 or 20 mg/kg increased the release of 5-HT and NE from the frontal cortex. The pharmacokinetic (PK) and brain penetration analyses suggest that H05 has favorable PK properties with good blood-brain penetration ability. Therefore, it can be concluded that H05, a novel serotonin and NE reuptake inhibitor with 5-HT 2A antagonist activity, possesses efficacious activity in the preclinical models of depression and treatment-resistant depression, and it may warrant further evaluation for clinical development. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

[Effect of (+/-)-pindolol on the central 5-HT1A receptor by the use of in vivo microdialysis and hippocampal slice preparations].

PubMed

Tsuji, Keiichiro

2002-06-01

Although it is suggested that (+/-)-pindolol, a beta-adrenergic/5-HT1A receptor antagonist, may enhance the efficacy of selective serotonin reuptake inhibitors (SSRI), the results of double-blind studies are contradictory and recent animal studies suggest that (+/-)-pindolol may act as a partial agonist to the 5-HT1A receptor. In this study we have investigated the effect of (+/-)-pindolol on both pre- and postsynaptic 5-HT1A receptors using in vivo microdialysis and hippocampal slice preparations. (+/-)-pindolol and flesinoxan, a 5-HT1A receptor full agonist, significantly decreased the extracellular levels of 5-HT in the raphe and prefrontal cortex. The 5-HT and other 5-HT1A receptor agonists, flesinoxan and 8-hydroxy-2- (di-n-propylamino)tetralon (8-OH-DPAT), significantly decreased the population excitatory postsynaptic potential (EPSP) in the CA3-CA1 excitatory synapse in a dose-dependent manner. The effect of 5-HT and other 5-HT1A receptor agonists accompanied the increase in paired-pulse facilitation (ppf) induced by short-interval two stimuli and were reversed by the coadministration of the 5-HT1A receptor agonist, NAN-190, but not by (+/-)-pindolol. (+/-)-pindolol also suppressed the EPSP, but this effect was not reversed by NAN-190. These results suggest that (+/-)-pindolol acts as a partial agonist to the somatodendritic 5-HT1A receptor in the raphe, whereas it may have no action on the postsynaptic 5-HT1A receptor in the hippocampus.

AN IN VIVO MICRODIALYSIS METHOD FOR THE QUALITATIVE ANALYSIS OF HEPATIC PHASE I METABOLITES OF PHENOL IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

EPA Science Inventory

Development of reliable and accurate methodologies for determination of xenobiotic hepatic biotransformation rate and capacity parameters is important to the derivation of precise physiologically-based toxicokinetic (PB-TK) models. Biotransformation data incorporated into PB-TK m...

Monoamine Release during Unihemispheric Sleep and Unihemispheric Waking in the Fur Seal

PubMed Central

Lyamin, Oleg I.; Lapierre, Jennifer L.; Kosenko, Peter O.; Kodama, Tohru; Bhagwandin, Adhil; Korneva, Svetlana M.; Peever, John H.; Mukhametov, Lev M.; Siegel, Jerome M.

2016-01-01

Study Objectives: Our understanding of the role of neurotransmitters in the control of the electroencephalogram (EEG) has been entirely based on studies of animals with bilateral sleep. The study of animals with unihemispheric sleep presents the opportunity of separating the neurochemical substrates of waking and sleep EEG from the systemic, bilateral correlates of sleep and waking states. Methods: The release of histamine (HI), norepinephrine (NE), and serotonin (5HT) in cortical and subcortical areas (hypothalamus, thalamus and caudate nucleus) was measured in unrestrained northern fur seals (Callorhinus ursinus) using in vivo microdialysis, in combination with, polygraphic recording of EEG, electrooculogram, and neck electromyogram. Results: The pattern of cortical and subcortical HI, NE, and 5HT release in fur seals is similar during bilaterally symmetrical states: highest in active waking, reduced in quiet waking and bilateral slow wave sleep, and lowest in rapid eye movement (REM) sleep. Cortical and subcortical HI, NE, and 5HT release in seals is highly elevated during certain waking stimuli and behaviors, such as being sprayed with water and feeding. However, in contrast to acetylcholine (ACh), which we have previously studied, the release of HI, NE, and 5HT during unihemispheric sleep is not lateralized in the fur seal. Conclusions: Among the studied neurotransmitters most strongly implicated in waking control, only ACh release is asymmetric in unihemispheric sleep and waking, being greatly increased on the activated side of the brain. Commentary: A commentary on this article appears in this issue on page 491. Citation: Lyamin OI, Lapierre JL, Kosenko PO, Kodama T, Bhagwandin A, Korneva SM, Peever JH, Mukhametov LM, Siegel JM. Monoamine release during unihemispheric sleep and unihemispheric waking in the fur seal. SLEEP 2016;39(3):625–636. PMID:26715233

Malignant infarction of the middle cerebral artery in a porcine model. A pilot study.

PubMed

Arikan, Fuat; Martínez-Valverde, Tamara; Sánchez-Guerrero, Ángela; Campos, Mireia; Esteves, Marielle; Gandara, Dario; Torné, Ramon; Castro, Lidia; Dalmau, Antoni; Tibau, Joan; Sahuquillo, Juan

2017-01-01

Interspecies variability and poor clinical translation from rodent studies indicate that large gyrencephalic animal stroke models are urgently needed. We present a proof-of-principle study describing an alternative animal model of malignant infarction of the middle cerebral artery (MCA) in the common pig and illustrate some of its potential applications. We report on metabolic patterns, ionic profile, brain partial pressure of oxygen (PtiO2), expression of sulfonylurea receptor 1 (SUR1), and the transient receptor potential melastatin 4 (TRPM4). A 5-hour ischemic infarct of the MCA territory was performed in 5 2.5-to-3-month-old female hybrid pigs (Large White x Landrace) using a frontotemporal approach. The core and penumbra areas were intraoperatively monitored to determine the metabolic and ionic profiles. To determine the infarct volume, 2,3,5-triphenyltetrazolium chloride staining and immunohistochemistry analysis was performed to determine SUR1 and TRPM4 expression. PtiO2 monitoring showed an abrupt reduction in values close to 0 mmHg after MCA occlusion in the core area. Hourly cerebral microdialysis showed that the infarcted tissue was characterized by reduced concentrations of glucose (0.03 mM) and pyruvate (0.003 mM) and increases in lactate levels (8.87mM), lactate-pyruvate ratio (4202), glycerol levels (588 μM), and potassium concentration (27.9 mmol/L). Immunohistochemical analysis showed increased expression of SUR1-TRPM4 channels. The aim of the present proof-of-principle study was to document the feasibility of a large animal model of malignant MCA infarction by performing transcranial occlusion of the MCA in the common pig, as an alternative to lisencephalic animals. This model may be useful for detailed studies of cerebral ischemia mechanisms and the development of neuroprotective strategies.

Dynamic changes in dopamine neuron function after DNSP-11 treatment: effects in vivo and increased ERK 1/2 phosphorylation in vitro.

PubMed

Fuqua, Joshua L; Littrell, Ofelia M; Lundblad, Martin; Turchan-Cholewo, Jadwiga; Abdelmoti, Lina G; Galperin, Emilia; Bradley, Luke H; Cass, Wayne A; Gash, Don M; Gerhardt, Greg A

2014-04-01

Glial cell-line derived neurotrophic factor (GDNF) has demonstrated robust effects on dopamine (DA) neuron function and survival. A post-translational processing model of the human GDNF proprotein theorizes the formation of smaller, amidated peptide(s) from the proregion that exhibit neurobiological function, including an 11-amino-acid peptide named dopamine neuron stimulating peptide-11 (DNSP-11). A single treatment of DNSP-11 was delivered to the substantia nigra in the rat to investigate effects on DA-neuron function. Four weeks after treatment, potassium (K+) and D-amphetamine evoked DA release were studied in the striatum using microdialysis. There were no significant changes in DA-release after DNSP-11 treatment determined by microdialysis. Dopamine release was further examined in discrete regions of the striatum using high-speed chronoamperometry at 1-, 2-, and 4-weeks after DNSP-11 treatment. Two weeks after DNSP-11 treatment, potassium-evoked DA release was increased in specific subregions of the striatum. However, spontaneous locomotor activity was unchanged by DNSP-11 treatment. In addition, we show that a single treatment of DNSP-11 in the MN9D dopaminergic neuronal cell line results in phosphorylation of ERK1/2, which suggests a novel cellular mechanism responsible for increases in DA function. Copyright © 2014 Elsevier Inc. All rights reserved.

Prolonged head-down tilt exposure reduces maximal cutaneous vasodilator and sweating capacity in humans

NASA Technical Reports Server (NTRS)

Crandall, C. G.; Shibasaki, M.; Wilson, T. E.; Cui, J.; Levine, B. D.

2003-01-01

Cutaneous vasodilation and sweat rate are reduced during a thermal challenge after simulated and actual microgravity exposure. The effects of microgravity exposure on cutaneous vasodilator capacity and on sweat gland function are unknown. The purpose of this study was to test the hypothesis that simulated microgravity exposure, using the 6 degrees head-down tilt (HDT) bed rest model, reduces maximal forearm cutaneous vascular conductance (FVC) and sweat gland function and that exercise during HDT preserves these responses. To test these hypotheses, 20 subjects were exposed to 14 days of strict HDT bed rest. Twelve of those subjects exercised (supine cycle ergometry) at 75% of pre-bed rest heart rate maximum for 90 min/day throughout HDT bed rest. Before and after HDT bed rest, maximal FVC was measured, via plethysmography, by heating the entire forearm to 42 degrees C for 45 min. Sweat gland function was assessed by administering 1 x 10(-6) to 2 M acetylcholine (9 doses) via intradermal microdialysis while simultaneously monitoring sweat rate over the microdialysis membranes. In the nonexercise group, maximal FVC and maximal stimulated sweat rate were significantly reduced after HDT bed rest. In contrast, these responses were unchanged in the exercise group. These data suggest that 14 days of simulated microgravity exposure, using the HDT bed rest model, reduces cutaneous vasodilator and sweating capacity, whereas aerobic exercise training during HDT bed rest preserves these responses.

In Vivo Methods for the Assessment of Topical Drug Bioavailability

PubMed Central

Herkenne, Christophe; Alberti, Ingo; Naik, Aarti; Kalia, Yogeshvar N.; Mathy, François-Xavier; Préat, Véronique

2007-01-01

This paper reviews some current methods for the in vivo assessment of local cutaneous bioavailability in humans after topical drug application. After an introduction discussing the importance of local drug bioavailability assessment and the limitations of model-based predictions, the focus turns to the relevance of experimental studies. The available techniques are then reviewed in detail, with particular emphasis on the tape stripping and microdialysis methodologies. Other less developed techniques, including the skin biopsy, suction blister, follicle removal and confocal Raman spectroscopy techniques are also described. PMID:17985216

Increased in vivo release of neuropeptide S in the amygdala of freely moving rats after local depolarisation and emotional stress.

PubMed

Ebner, Karl; Rjabokon, Alesja; Pape, Hans-Christian; Singewald, Nicolas

2011-10-01

Intracerebral microdialysis in conjunction with a highly sensitive radioimmunoassay was used to study the in vivo release of neuropeptide S (NPS) within the amygdala of freely moving rats. NPS was consistently detected in basolateral amygdala dialysates and the release considerably enhanced in response to local depolarisation as well as exposure to forced swim stress. Thus, our data demonstrate for the first time emotional stress-induced release of NPS in the amygdala supporting a functional role of endogenous NPS in stress/anxiety-related phenomena.

The Role of Glutamate Release on Voltage-Dependent Anion Channels (VDAC)-Mediated Apoptosis in an Eleven Vessel Occlusion Model in Rats

PubMed Central

Park, Eunkuk; Lee, Gi-Ja; Choi, Samjin; Choi, Seok-Keun; Chae, Su-Jin; Kang, Sung-Wook; Pak, Youngmi Kim; Park, Hun-Kuk

2010-01-01

Voltage-dependent anion channel (VDAC) is the main protein in mitochondria-mediated apoptosis, and the modulation of VDAC may be induced by the excessive release of extracellular glutamate. This study examined the role of glutamate release on VDAC-mediated apoptosis in an eleven vessel occlusion model in rats. Male Sprague-Dawley rats (250–350 g) were used for the 11 vessel occlusion ischemic model, which were induced for a 10-min transient occlusion. During the ischemic and initial reperfusion episode, the real-time monitoring of the extracellular glutamate concentration was measured using an amperometric microdialysis biosensor and the cerebral blood flow (CBF) was monitored by laser-Doppler flowmetry. To confirm neuronal apoptosis, the brains were removed 72 h after ischemia to detect the neuron-specific nuclear protein and pro-apoptotic proteins (cleaved caspase-3, VDAC, p53 and BAX). The changes in the mitochondrial morphology were measured by atomic force microscopy. A decrease in the % of CBF was observed, and an increase in glutamate release was detected after the onset of ischemia, which continued to increase during the ischemic period. A significantly higher level of glutamate release was observed in the ischemia group. The increased glutamate levels in the ischemia group resulted in the activation of VDAC and pro-apoptotic proteins in the hippocampus with morphological alterations to the mitochondria. This study suggests that an increase in glutamate release promotes VDAC-mediated apoptosis in an 11 vessel occlusion ischemic model. PMID:21203570

Cardiovascular responses and neurotransmitter changes during static muscle contraction following blockade of inducible nitric oxide synthase (iNOS) within the ventrolateral medulla.

PubMed

Ally, Ahmmed; Phattanarudee, Siripan; Kabadi, Shruti; Patel, Maitreyee; Maher, Timothy J

2006-05-23

The enzyme nitric oxide synthase (NOS) which is necessary for the production of nitric oxide from L-arginine exists in three isoforms: neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS). Our previous studies have demonstrated the roles of nNOS and eNOS within the rostral (RVLM) and caudal ventrolateral medulla (CVLM) in modulating cardiovascular responses during static skeletal muscle contraction via altering localized glutamate and GABA levels (Brain Res. 977 (2003) 80-89; Neuroscience Res. 52 (2005) 21-30). In this study, we investigated the role of iNOS within the RVLM and CVLM on cardiovascular responses and glutamatergic/GABAergic neurotransmission during the exercise pressor reflex. Bilateral microdialysis of a selective iNOS antagonist, aminoguanidine (AGN; 1.0 microM), for 60 min into the RVLM attenuated increases in mean arterial pressure (MAP), heart rate (HR), and extracellular glutamate levels during a static muscle contraction. Levels of GABA within the RVLM were increased. After 120 min of discontinuation of the drug, MAP and HR responses and glutamate/GABA concentrations recovered to baseline values during a subsequent muscle contraction. In contrast, bilateral application of AGN (1.0 microM) into CVLM potentiated cardiovascular responses and glutamate concentration while attenuating levels of GABA during a static muscle contraction. All values recovered after 120 min of discontinuation of the drug. These results demonstrate that iNOS within the ventrolateral medulla plays an important role in modulating cardiovascular responses and glutamatergic/GABAergic neurotransmission that regulates the exercise pressor reflex.

The AMP-activated protein kinase is involved in the regulation of ketone body production by astrocytes.

PubMed

Blázquez, C; Woods, A; de Ceballos, M L; Carling, D; Guzmán, M

1999-10-01

The possible role of the AMP-activated protein kinase (AMPK), a highly conserved stress-activated kinase, in the regulation of ketone body production by astrocytes was studied. AMPK activity in rat cortical astrocytes was three times higher than in rat cortical neurons. AMPK in astrocytes was shown to be functionally active. Thus, incubation of astrocytes with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a cell-permeable activator of AMPK, stimulated both ketogenesis from palmitate and carnitine palmitoyltransferase I. This was concomitant to a decrease of intracellular malonyl-CoA levels and an inhibition of acetyl-CoA carboxylase/fatty acid synthesis and 3-hydroxy-3-methylglutaryl-CoA reductase/cholesterol synthesis. Moreover, in microdialysis experiments AICAR was shown to stimulate brain ketogenesis markedly. The effect of chemical hypoxia on AMPK and the ketogenic pathway was studied subsequently. Incubation of astrocytes with azide led to a remarkable drop of fatty acid beta-oxidation. However, activation of AMPK during hypoxia compensated the depression of beta-oxidation, thereby sustaining ketone body production. This effect seemed to rely on the cascade hypoxia --> increase of the AMP/ATP ratio --> AMPK stimulation --> acetyl-CoA carboxylase inhibition --> decrease of malonyl-CoA concentration --> carnitine palmitoyltransferase I deinhibition --> enhanced ketogenesis. Furthermore, incubation of neurons with azide blunted lactate oxidation, but not 3-hydroxybutyrate oxidation. Results show that (a) AMPK plays an active role in the regulation of ketone body production by astrocytes, and (b) ketone bodies produced by astrocytes during hypoxia might be a substrate for neuronal oxidative metabolism.

Exercise leads to the re-emergence of the cholinergic/nestin neuronal phenotype within the medial septum/diagonal band and subsequent rescue of both hippocampal ACh efflux and spatial behavior.

PubMed

Hall, Joseph M; Savage, Lisa M

2016-04-01

Exercise has been shown to improve cognitive functioning in a range of species, presumably through an increase in neurotrophins throughout the brain, but in particular the hippocampus. The current study assessed the ability of exercise to restore septohippocampal cholinergic functioning in the pyrithiamine-induced thiamine deficiency (PTD) rat model of the amnestic disorder Korsakoff Syndrome. After voluntary wheel running or sedentary control conditions (stationary wheel attached to the home cage), PTD and control rats were behaviorally tested with concurrent in vivo microdialysis, at one of two time points: 24-h or 2-weeks post-exercise. It was found that only after the 2-week adaption period did exercise lead to an interrelated sequence of events in PTD rats that included: (1) restored spatial working memory; (2) rescued behaviorally-stimulated hippocampal acetylcholine efflux; and (3) within the medial septum/diagonal band, the re-emergence of the cholinergic (choline acetyltransferase [ChAT+]) phenotype, with the greatest change occurring in the ChAT+/nestin+ neurons. Furthermore, in control rats, exercise followed by a 2-week adaption period improved hippocampal acetylcholine efflux and increased the number of neurons co-expressing the ChAT and nestin phenotype. These findings demonstrate a novel mechanism by which exercise can modulate the mature cholinergic/nestin neuronal phenotype leading to improved neurotransmitter function as well as enhanced learning and memory. Copyright © 2016 Elsevier Inc. All rights reserved.

5-HT has contrasting effects in the frontal cortex, but not the hypothalamus, on changes in noradrenaline efflux induced by the monoamine releasing-agent, d-amphetamine, and the reuptake inhibitor, BTS 54 354.

PubMed

Géranton, Sandrine M; Heal, David J; Stanford, S Clare

2004-03-01

There is extensive evidence for functional interactions between central noradrenergic and serotonergic neurones. Here, dual-probe microdialysis was used in freely-moving rats to compare the effects of 5-HT on noradrenergic transmission in the rat frontal cortex and hypothalamus. We studied the effects of the 5-HT synthesis inhibitor, para-chlorophenylalanine (pCPA; which depleted 5-HT stores in both the frontal cortex and the hypothalamus), on spontaneous efflux of noradrenaline and on the noradrenergic responses to d-amphetamine, and the monoamine reuptake inhibitor, BTS 54 354. pCPA pretreatment alone did not affect spontaneous noradrenaline efflux in either brain region, whether or not alpha2-autoreceptors were inactivated by administration of the alpha2-antagonist, atipamezole (1 mg/kg i.p). However, in the frontal cortex, pCPA pretreatment augmented the amplitude of, and prolonged, the noradrenergic response to local infusion of d-amphetamine (10 microM). In contrast, pCPA abolished the increase in cortical noradrenaline efflux induced by local infusion of BTS 54 354 (50 microM). In the hypothalamus, pCPA did not affect the amplitude of the response to either of these agents but did prolong the effects of d-amphetamine on noradrenaline efflux. These findings suggest that serotonergic transmission has complex effects on the noradrenergic response to drugs that increase noradrenergic transmission in the frontal cortex, but has less influence in the hypothalamus.

Acetylcholine Release in the Hippocampus and Striatum during Place and Response Training

ERIC Educational Resources Information Center

Pych, Jason C.; Chang, Qing; Colon-Rivera, Cynthia; Haag, Renee; Gold, Paul E.

2005-01-01

These experiments examined the release of acetylcholine in the hippocampus and striatum when rats were trained, within single sessions, on place or response versions of food-rewarded mazes. Microdialysis samples of extra-cellular fluid were collected from the hippocampus and striatum at 5-min increments before, during, and after training. These…

Methods to measure target site penetration of antibiotics in critically ill patients.

PubMed

Schwameis, Richard; Zeitlinger, Markus

2013-02-01

While several tools are necessary to repair a car, the engineer knows exactly which instrument he has to utilize at different parts of the broken machine. Likewise, depending on the information we are interested in, we have to choose different tools to investigate and consecutively understand the multiple aspects that are involved in pharmacokinetics of antimicrobial agents in critically ill patients. Some techniques, like blood sampling, microdialysis or positrons emission tomography (PET) will allow for obtaining continues concentration time profiles while others like bronchoalveolar lavage (BAL), biopsy or surgical tissue samples can only be used a limited number of times per subject. PET and methods based on tissue homogenization will deliver an average of the actual concentrations in intra - and extracellular compartments while investigations in isolated blood cells or microdialysis allow for more distinguished allocation of a concentration to a defined compartment. The present review aims at discussing the advantages and disadvantages of the various methods used for assessing pharmacokinetics in critically ill patients with regard to specific aspects of pharmacokinetic research and further reviews data of selected antibiotics as examples for applications of the individual techniques.

Crystallization and preliminary X-ray analysis of a novel thermoalkalophilic poly(3-hydroxybutyrate) depolymerase (PhaZ7) from Paucimonas lemoignei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapetaniou, Evangelia G.; Braaz, Reinhard; Jendrossek, Dieter

2005-05-01

A novel thermoalkalophilic depolymerase, PhaZ7, from P. lemoignei was crystallized by the microdialysis technique. Crystals belong to space group C2 and diffract to 2.75 Å resolution at a synchrotron source. Polyhydroxyalkanoates (PHA) are biodegradable polyesters that have attracted commercial and academic interest as environmentally friendly materials. A number of enzymes are able to degrade polyhydroxyalkanoates to water-soluble products. PhaZ7 poly(3-hydroxybutyrate) (PHB) depolymerase (EC 3.1.1.75), a 342-amino-acid hydrolase from the PHA-degrading bacterium Paucimonas lemoignei, has been found to possess substrate specificity for amorphous PHA. PhaZ7 was crystallized by the microdialysis method. Thin rod-like crystals were grown in low ionic strength solutionmore » and found to belong to the monoclinic space group C2, with unit-cell parameters a = 225.8, b = 46.5, c = 171.3, β = 128.9°. A complete data set was collected to 2.75 Å resolution at 100 K using synchrotron radiation.« less

Tolerance to 3,4-Methylenedioxymethamphetamine (MDMA) in Rats Exposed to Single High-Dose Binges

PubMed Central

Baumann, Michael H.; Clark, Robert D.; Franken, Frederick H.; Rutter, John J.; Rothman, Richard B.

2008-01-01

3,4-Methylenedioxymethamphetamine (MDMA or Ecstasy) stimulates the transporter-mediated release of monoamines, including serotonin (5-HT). High-dose exposure to MDMA causes persistent 5-HT deficits (e.g., depletion of brain 5-HT) in animals, yet the functional and clinical relevance of such deficits are poorly defined. Here we examine functional consequences of MDMA-induced 5-HT depletions in rats. Male rats received binges of 3 ip injections of MDMA or saline, one injection every 2 h; MDMA was given at a threshold pharmacological dose (1.5 mg/kg × 3, low dose) or at a 5-fold higher amount (7.5 mg/kg × 3, high dose). One week later, jugular catheters and intracerebral guide cannulae were implanted. Two weeks after binges, rats received acute iv challenge injections of 1 and 3 mg/kg MDMA. Neuroendocrine effects evoked by iv MDMA (prolactin and corticosterone secretion) were assessed via serial blood sampling, while neurochemical effects (5-HT and dopamine release) were assessed via microdialysis in brain. MDMA binges elevated core temperatures only in the high-dose group, with these same rats exhibiting ~50% loss of forebrain 5-HT two weeks later. Prior exposure to MDMA did not alter baseline plasma hormones or dialysate monoamines, and effects of iv MDMA were similar in saline and low-dose groups. By contrast, rats pretreated with high-dose MDMA displayed significant reductions in evoked hormone secretion and 5-HT release when challenged with iv MDMA. As tolerance developed only in rats exposed to high-dose binges, hyperthermia and 5-HT depletion are implicated in this phenomenon. Our results suggest that MDMA tolerance in humans may reflect 5-HT deficits which could contribute to further dose escalation. PMID:18313226

Brain serotonin content regulates the manifestation of tramadol-induced seizures in rats: disparity between tramadol-induced seizure and serotonin syndrome.

PubMed

Fujimoto, Yohei; Funao, Tomoharu; Suehiro, Koichi; Takahashi, Ryota; Mori, Takashi; Nishikawa, Kiyonobu

2015-01-01

Tramadol-induced seizures might be pathologically associated with serotonin syndrome. Here, the authors investigated the relationship between serotonin and the seizure-inducing potential of tramadol. Two groups of rats received pretreatment to modulate brain levels of serotonin and one group was treated as a sham control (n = 6 per group). Serotonin modulation groups received either para-chlorophenylalanine or benserazide + 5-hydroxytryptophan. Serotonin, dopamine, and histamine levels in the posterior hypothalamus were then measured by microdialysis, while simultaneously infusing tramadol until seizure onset. In another experiment, seizure threshold with tramadol was investigated in rats intracerebroventricularly administered with either a serotonin receptor antagonist (methysergide) or saline (n = 6). Pretreatment significantly affected seizure threshold and serotonin fluctuations. The threshold was lowered in para-chlorophenylalanine group and raised in benserazide + 5-hydroxytryptophan group (The mean ± SEM amount of tramadol needed to induce seizures; sham: 43.1 ± 4.2 mg/kg, para-chlorophenylalanine: 23.2 ± 2.8 mg/kg, benserazide + 5-hydroxytryptophan: 59.4 ± 16.5 mg/kg). Levels of serotonin at baseline, and their augmentation with tramadol infusion, were less in the para-chlorophenylalanine group and greater in the benserazide + 5-hydroxytryptophan group. Furthermore, seizure thresholds were negatively correlated with serotonin levels (correlation coefficient; 0.71, P < 0.01), while intracerebroventricular methysergide lowered the seizure threshold (P < 0.05 vs. saline). The authors determined that serotonin-reduced rats were predisposed to tramadol-induced seizures, and that serotonin concentrations were negatively associated with seizure thresholds. Moreover, serotonin receptor antagonism precipitated seizure manifestation, indicating that tramadol-induced seizures are distinct from serotonin syndrome.

Effect of Buyang Huanwu decoction on amino acid content in cerebrospinal fluid of rats during ischemic/reperfusion injury.

PubMed

Wang, Lisheng; Huang, Yuwei; Wu, Junhong; Lv, Gengbin; Zhou, Liling; Jia, Jie

2013-12-01

The inhibitory effect of Buyang Huanwu decoction (BYHWD) on ischemic injury has been proven, but it is not clear how amino acid levels in cerebrospinal fluid (CSF) are associated with BYHWD treatment, nor the mechanism by which BYHWD protects the brain from ischemia/reperfusion injury. We investigated the effect of BYHWD on the amino acid content of CSF in rats during ischemia-reperfusion injury. Ischemia was imposed by right middle cerebral artery occlusion (MCAO). CSF was continuously collected from the striatum via brain microdialysis before and after ischemia/reperfusion. We used on-line derivatization combined with high-performance liquid chromatography with fluorescence detection (HPLC-FD) to determine levels of glutamate (Glu), aspartate (Asp), glycine (Gly), taurine (Tau), and γ-aminobutyric acid (GABA) in CSF. The MCAO model displayed an infarct lesion in the ipsilateral hemisphere and nerve injuries, as the left upper limb was unable to extend and turn leftward. Significant increases in excitatory and inhibitory amino acids were observed in the CSF of the ischemic rats relative to the sham-operated group (P<0.01). Treatment with BYHWD reduced the areas of cerebral infarction and improved the neurological behavior scores of rats after MCAO. BYHWD treatment was also associated with a significant decrease in excitatory amino acids and increase in inhibitory amino acids in the CSF. Only the higher dose of BYHWD (20mg/kg) affected all these levels significantly. Attenuated excitatory toxicity and reduced areas of cerebral infarction associated with BYHWD treatment might be due to a protective mechanism induced by BYHWD against ischemia/reperfusion injury. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison between male and female rats in a model of self-administration of a chocolate-flavored beverage: Behavioral and neurochemical studies.

PubMed

Contini, Andrea; Sanna, Fabrizio; Maccioni, Paola; Colombo, Giancarlo; Argiolas, Antonio

2018-05-15

The existence of sex differences was studied in a rat model of operant self-administration of a chocolate-flavored beverage (CFB), which possesses strong reinforcing properties and is avidly consumed by rats. Whether these differences occurred concomitantly to changes in extracellular dopamine in the dialysate obtained from the nucleus accumbens, was assessed by intracerebral microdialysis. Male, ovariectomized and intact female rats showed similar self-administration profiles, with minor differences in both acquisition and maintenance phases. Intact females self-administered larger amounts of CFB, when expressed per body weight, than males and ovariectomized females, in spite of similar values of lever-responding, latency to the first lever-response and consumption efficiency (a measure of rat's licking effectiveness) in males, ovariectomized and intact females and no difference in breakpoint value and number of lever-responses emerged when males, ovariectomized and intact females were exposed to a progressive ratio schedule of reinforcement. Intracerebral microdialysis revealed a slight but significant increase in dopamine activity in the shell of the nucleus accumbens of male rats when compared to intact female rats during CFB self-administration. The above differences may be caused by the hormonal (mainly estradiol) fluctuations that occur during the estrus cycle in intact females. Accordingly, in intact females CFB self-administration and dopamine activity were found to fluctuate across the estrus cycle, with lower parameters of CFB self-administration and lower dopamine activity in the Proestrus and Estrus phases vs. the Metestrus and Diestrus phases of the cycle. Copyright © 2018 Elsevier B.V. All rights reserved.

Differential impact of pavlovian drug conditioned stimuli on in vivo dopamine transmission in the rat accumbens shell and core and in the prefrontal cortex.

PubMed

Bassareo, Valentina; De Luca, Maria Antonietta; Di Chiara, Gaetano

2007-04-01

Conditioned stimuli (CSs) by pavlovian association with reinforcing drugs (US) are thought to play an important role in the acquisition, maintenance and relapse of drug dependence. The aim of this study was to investigate by microdialysis the impact of pavlovian drug CSs on behaviour and on basal and drug-stimulated dopamine (DA) in three terminal DA areas: nucleus accumbens shell, core and prefrontal cortex (PFCX). Conditioned rats were trained once a day for 3 days by presentation of Fonzies filled box (FFB, CS) for 10 min followed by administration of morphine (1 mg/kg), nicotine (0.4 mg/kg) or saline, respectively. Pseudo-conditioned rats were presented with the FFB 10 h after drug or saline administration. Rats were implanted with microdialysis probes in the shell, core and PFCX. The effect of stimuli conditioned with morphine and nicotine on DA and on DA response to drugs was studied. Drug CSs elicited incentive reactions and released DA in the shell and PFCX but not in the core. Pre-exposure to morphine CS potentiated DA release to morphine challenge in the shell but not in the core and PFCX. This effect was related to the challenge dose of morphine and was stimulus-specific since a food CS did not potentiate the shell DA response to morphine. Pre-exposure to nicotine CS potentiated DA release in the shell and PFCX. The results show that drug CSs stimulate DA release in the shell and medial PFCX and specifically potentiate the primary stimulant drug effects on DA transmission.

Fast and sensitive HPLC/UV method for cefazolin quantification in plasma and subcutaneous tissue microdialysate of humans and rodents applied to pharmacokinetic studies in obese individuals.

PubMed

Palma, Eduardo Celia; Laureano, João Victor; de Araújo, Bibiana Verlindo; Meinhardt, Nelson Guardiola; Stein, Airton Tetelbom; Dalla Costa, Teresa

2018-04-14

Antimicrobial prophylactic dosing of morbidly obese patients may differ from normal weighted individuals owing to alterations in drug tissue distribution. Drug subcutaneous tissue distribution can be investigated by microdialysis patients and animals. The need for cefazolin prophylactic dose adjustment in obese patients remains under discussion. The paper describes the validation of an HPLC-UV method for cefazolin quantification in plasma and microdialysate samples from clinical and pre-clinical studies. A C 18 column with an isocratic mobile phase was used for drug separation, with detection at 272 nm. Total and unbound cefazolin lower limit of quantitation was 5 μg/mL in human plasma, 2 μg/mL in rat plasma, and 0.5 and 0.025 μg/mL in human and rat microdialysate samples, respectively. The maximum intra- and inter-day imprecisions were 10.7 and 8.1%, respectively. The inaccuracy was <9.7%. The limit of quantitation imprecision and inaccuracy were < 15%. Cefazolin stability in the experimental conditions was confirmed. Cefazolin plasma concentrations and subcutaneous tissue penetration were determined by microdialysis in morbidly obese patients (2 g i.v. bolus) and diet-induced obese rats (30 mg/kg i.v. bolus) using the method. This method has the main advantages of easy plasma clean-up and practicability and has proven to be useful in cefazolin clinical and pre-clinical pharmacokinetic investigations. Copyright © 2018 John Wiley & Sons, Ltd.

Specific multi-nutrient enriched diet enhances hippocampal cholinergic transmission in aged rats.

PubMed

Cansev, Mehmet; van Wijk, Nick; Turkyilmaz, Mesut; Orhan, Fulya; Sijben, John W C; Broersen, Laus M

2015-01-01

Fortasyn Connect (FC) is a specific nutrient combination designed to target synaptic dysfunction in Alzheimer's disease by providing neuronal membrane precursors and other supportive nutrients. The aim of the present study was to investigate the effects of FC on hippocampal cholinergic neurotransmission in association with its effects on synaptic membrane formation in aged rats. Eighteen-month-old male Wistar rats were randomized to receive a control diet for 4 weeks or an FC-enriched diet for 4 or 6 weeks. At the end of the dietary treatments, acetylcholine (ACh) release was investigated by in vivo microdialysis in the right hippocampi. On completion of microdialysis studies, the rats were sacrificed, and the left hippocampi were obtained to determine the levels of choline, ACh, membrane phospholipids, synaptic proteins, and choline acetyltransferase. Our results revealed that supplementation with FC diet for 4 or 6 weeks, significantly enhanced basal and stimulated hippocampal ACh release and ACh tissue levels, along with levels of phospholipids. Feeding rats the FC diet for 6 weeks significantly increased the levels of choline acetyltransferase, the presynaptic marker Synapsin-1, and the postsynaptic marker PSD-95, but decreased levels of Nogo-A, a neurite outgrowth inhibitor. These data show that the FC diet enhances hippocampal cholinergic neurotransmission in aged rats and suggest that this effect is mediated by enhanced synaptic membrane formation. These data provide further insight into cellular and molecular mechanisms by which FC may support memory processes in Alzheimer's disease. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

The complexity of minocycline serum protein binding.

PubMed

Zhou, Jian; Tran, Brian T; Tam, Vincent H

2017-06-01

Serum protein binding is critical for understanding the pharmacology of antimicrobial agents. Tigecycline and eravacycline were previously reported to have atypical non-linear protein binding; the percentage of free fraction decreased with increasing total concentration. In this study, we extended the investigation to other tetracyclines and examined the factors that might impact protein binding. Different minocycline concentrations (0.5-50 mg/L) and perfusion media (saline, 0.1 M HEPES buffer and 0.1 and 1 M PBS) were examined by in vitro microdialysis. After equilibration, two dialysate samples were taken from each experiment and the respective antimicrobial agent concentrations were analysed by validated LC-MS/MS methods. For comparison, the serum protein bindings of doxycycline and levofloxacin were also determined. The free fraction of minocycline decreased with increasing total concentration, and the results depended on the perfusion media used. The trends of minocycline protein binding in mouse and human sera were similar. In addition, serum protein binding of doxycycline showed the same concentration-dependent trend as minocycline, while the results of levofloxacin were concentration independent. The serum protein bindings of minocycline and doxycycline are negatively correlated with their total concentrations. It is possible that all tetracyclines share the same pharmacological property. Moreover, the specific perfusion media used could also impact the results of microdialysis. Additional studies are warranted to understand the mechanism(s) and clinical implications of serum protein binding of tetracyclines. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evaluation of intraprostatic metabolism of 1,25-dihydroxyvitamin D(3) (calcitriol) using a microdialysis technique.

PubMed

Konety, Badrinath R; Somogyi, George; Atan, Ali; Muindi, Josephia; Chancellor, Michael B; Getzenberg, Robert H

2002-06-01

1,25-dihydroxyvitamin D(3) (calcitriol) inhibits prostate cancer growth in vitro and in vivo. We used a prostate microdialysis technique to better understand the intraprostatic pharmacokinetics of calcitriol, which in turn would facilitate planning for systemic calcitriol therapy in patients with prostate cancer. Male Sprague-Dawley rats were treated with 5 microg of calcitriol intravenously. Animals were either intact (group 1, n = 6) or castrated (group 2, n = 3). Prostate microdialysis was performed by perfusing Krebs solution through a 5-mm linear probe. Effluents were collected hourly from 0 to 20 hours or until death. Serum was collected at baseline and at the end of the experiment. Serum was also obtained from untreated rats at 0, 1, 2, 3, 4, 6, 8, 12, and 24 hours after intraperitoneal injection of calcitriol. Calcitriol levels were measured by radioimmunoassay. The average baseline intraprostatic level of calcitriol in prostate dialysate in intact rats was 21.1 pg/mL (+/-7.5); it was 88 pg/mL (+/-98.4) after calcitriol administration. In castrated animals, the values were 16.6 pg/mL (+/-5.3) and 25.3 pg/mL (+/-10.7). Two peaks in intraprostatic calcitriol levels were observed after intravenous administration: at less than 6 hours after injection and at more than 13 hours after injection. The mean total calcitriol exposure (area under the concentration versus time curve) in the prostate was 297.6 (+/-159) pg/hr/mL (intact) and 272.7 (+/-123.6) pg/hr/mL (castrated). The baseline serum levels were 0.1 to 1 ng/mL and reached a peak of more than 100 ng/mL within 1 hour of intraperitoneal injection. This technique permits real-time measurement of intraprostatic pharmacokinetics of calcitriol. The ratio of the intraprostatic area under the concentration versus time curve to the serum area under the concentration versus time curve of calcitriol was less than 1:100. Hence, within 24 hours of calcitriol administration, only a fraction (less than 1%) of the serum level is detectable in prostatic tissue. A bimodal peak in intraprostatic calcitriol levels is observed. This technique could be used to determine the tissue levels of calcitriol more accurately and to conduct additional studies to better elucidate the effects of castration on the intraprostatic pharmacokinetics of calcitriol.

Dopamine transporter-dependent and -independent actions of trace amine beta-phenylethylamine.

PubMed

Sotnikova, Tatyana D; Budygin, Evgeny A; Jones, Sara R; Dykstra, Linda A; Caron, Marc G; Gainetdinov, Raul R

2004-10-01

Beta-phenylethylamine (beta-PEA) is an endogenous amine that is found in trace amounts in the brain. It is believed that the locomotor-stimulating action of beta-PEA, much like amphetamine, depends on its ability to increase extracellular dopamine (DA) concentrations owing to reversal of the direction of dopamine transporter (DAT)-mediated DA transport. beta-PEA can also bind directly to the recently identified G protein-coupled receptors, but the physiological significance of this interaction is unclear. To assess the mechanism by which beta-PEA mediates its effects, we compared the neurochemical and behavioral effects of this amine in wild type (WT), heterozygous and 'null' DAT mutant mice. In microdialysis studies, beta-PEA, administered either systemically or locally via intrastriatal infusion, produced a pronounced outflow of striatal DA in WT mice whereas no increase was detected in mice lacking the DAT (DAT-KO mice). Similarly, in fast-scan voltammetry studies beta-PEA did not alter DA release and clearance rate in striatal slices from DAT-KO mice. In behavioral studies beta-PEA produced a robust but transient increase in locomotor activity in WT and heterozygous mice. In DAT-KO mice, whose locomotor activity and stereotypy are increased in a novel environment, beta-PEA (10-100 mg/kg) exerted a potent inhibitory action. At high doses, beta-PEA induced stereotypies in WT and heterozygous mice; some manifestations of stereotypy were also observed in the DAT-KO mice. These data demonstrate that the DAT is required for the striatal DA-releasing and hyperlocomotor actions of beta-PEA. The inhibitory action on hyperactivity and certain stereotypies induced by beta-PEA in DAT-KO mice indicate that targets other than the DAT are responsible for these effects.

Monoaminergic Psychomotor Stimulants: Discriminative Stimulus Effects and Dopamine Efflux

PubMed Central

Desai, Rajeev I.; Paronis, Carol A.; Martin, Jared; Desai, Ramya

2010-01-01

The present studies were conducted to investigate the relationship between discriminative stimulus effects of indirectly acting monoaminergic psychostimulants and their ability to increase extracellular levels of dopamine (DA) in the nucleus accumbens (NAcb) shell. First, the behavioral effects of methamphetamine (MA), cocaine (COC), 1-[2-[bis(4-fluorophenyl-)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR 12909), d-amphetamine, and methylphenidate were established in rats trained to discriminate intraperitoneal injections of 0.3 mg/kg MA from saline. In other studies, in vivo microdialysis was used to determine the effects of MA, COC, and GBR 12909 on extracellular DA levels in the NAcb shell. Results show that all drugs produced dose-related and full substitution for the discriminative stimulus effects of 0.3 mg/kg MA. In microdialysis studies, cumulatively administered MA (0.3–3 mg/kg), COC (3–56 mg/kg), and GBR 12909 (3–30 mg/kg) produced dose-dependent increases in DA efflux in the NAcb shell to maxima of approximately 1200 to 1300% of control values. The increase in DA levels produced by MA and COC was rapid and short-lived, whereas the effect of GBR 12909 was slower and longer lasting. Dose-related increases in MA lever selection produced by MA, COC, and GBR 12909 corresponded with graded increases in DA levels in the NAcb shell. Doses of MA, COC, and GBR 12909 that produced full substitution increased DA levels to approximately 200 to 400% of control values. Finally, cumulatively administered MA produced comparable changes in DA levels in both naive and 0.3 mg/kg MA-trained rats. These latter results suggest that sensitization of DA release does not play a prominent role in the discriminative stimulus effects of psychomotor stimulants. PMID:20190012

The neuropharmacology of prolactin secretion elicited by 3,4-methylenedioxymethamphetamine (“ecstasy”): A concurrent microdialysis and plasma analysis study

PubMed Central

Murnane, K.S.; Kimmel, H.L.; Rice, K.C.; Howell, L.L

2012-01-01

3,4-methylenedioxymethamphetamine (MDMA) is a substituted phenethylamine that is widely abused as the street drug “ecstasy”. Racemic MDMA (S,R(+/−)-MDMA) and its stereoisomers elicit complex spectrums of psychobiological, neurochemical, and hormonal effects. In this regard, recent findings demonstrated that S,R(+/−)-MDMA and its stereoisomer R(−)-MDMA elicit increases in striatal extracellular serotonin levels and plasma levels of the hormone prolactin in rhesus monkeys. In the present mechanistic study, we evaluated the role of the serotonin transporter and the 5-HT2A receptor in S,R(+/−)-MDMA- and R(−)-MDMA-elicited prolactin secretion in rhesus monkeys through concurrent microdialysis and plasma analysis determinations and drug interaction experiments. Concurrent neurochemical and hormone determinations showed a strong positive temporal correlation between serotonin release and prolactin secretion. Consistent with their distinct mechanisms of action and previous studies showing that the serotonin transporter inhibitor fluoxetine attenuates the behavioral and neurochemical effects of S,R(+/−)-MDMA, pretreatment with fluoxetine attenuated serotonin release elicited by either S,R(+/−)-MDMA or R(−)-MDMA. As hypothesized, at a dose that had no significant effects on circulating prolactin levels when administered alone, fluoxetine also attenuated prolactin secretion elicited by S,R(+/−)-MDMA. In contrast, combined pretreatment with both fluoxetine and the selective 5-HT2A receptor antagonist M100907 was required to attenuate prolactin secretion elicited by R(−)-MDMA, suggesting that this stereoisomer of S,R(+/−)-MDMA elicits prolactin secretion through both serotonin release and direct agonism of 5-HT2A receptors. Accordingly, these findings inform our understanding of the neuropharmacology of both S,R(+/−)-MDMA and R(−)-MDMA and the regulation of prolactin secretion. PMID:22197270

A genetic determinant of the striatal dopamine response to alcohol in men

PubMed Central

Ramchandani, Vijay A.; Umhau, John; Pavon, Francisco J.; Ruiz-Velasco, Victor; Margas, Wojciech; Sun, Hui; Damadzic, Ruslan; Eskay, Robert; Schoor, Michael; Thorsell, Annika; Schwandt, Melanie L.; Sommer, Wolfgang H.; George, David T.; Parsons, Loren H.; Herscovitch, Peter; Hommer, Daniel; Heilig, Markus

2010-01-01

Excessive alcohol use, a major cause of morbidity and mortality, is less well understood than other addictive disorders. Dopamine release in ventral striatum is a common element of drug reward, but alcohol has an unusually complex pharmacology, and humans vary greatly in their alcohol responses. This variation is related to genetic susceptibility for alcoholism, which contributes more than half of alcoholism risk. Here, we report that a functional OPRM1 A118G polymorphism is a major determinant of striatal dopamine responses to alcohol. Social drinkers recruited based on OPRM1 genotype were challenged in separate sessions with alcohol and placebo under pharmacokinetically controlled conditions, and examined for striatal dopamine release using positron emission tomography and [11C]-raclopride displacement. A striatal dopamine response to alcohol was restricted to carriers of the minor 118G allele. To directly establish the causal role of OPRM1 A118G variation, we generated two humanized mouse lines, carrying the respective human sequence variant. Brain microdialysis showed a four-fold greater peak dopamine response to an alcohol challenge in h/mOPRM1-118GG than in h/mOPRM1-118AA mice. OPRM1 A118G variation is a genetic determinant of dopamine responses to alcohol, a mechanism by which it likely modulates alcohol reward. PMID:20479755

SYSTEMIC ADMINISTRATION OF KAINIC ACID INCREASES GABA LEVELS IN PERFUSATE FROM THE HIPPOCAMPUS OF RATS IN VIVO

EPA Science Inventory

The ventral hippocampi of male, Fischer-344 rats were implanted with microdialysis probes and the effects of systemically administered kainic acid (KA) (8 mg/kg, s.c.) on the in vivo release of amino acids were measured for four hours after administration. n order to measure GABA...

IN VIVO KINETICS OF PHENYLGLUCURONIDE, A PHASE II CONJUGATE OF PHENOLE, IN BLOOD AND URINE OF RAINBOW TROUT

EPA Science Inventory

The kinetics of phenylglucuronide (PG) in blood and urine of spinally-transected rainbow trout were investigated using microdialysis sampling techniques. Trout weighing 0.9 to 1.3 kg were dosed continuously with PG for an additional 48 h. PG could not be detected in expired branc...

Is chlormethiazole neuroprotective in experimental global cerebral ischemia? A microdialysis and behavioral study.

PubMed

Thaminy, S; Reymann, J M; Heresbach, N; Allain, H; Lechat, P; Bentué-Ferrer, D

1997-04-01

Chlormethiazole, an anticonvulsive agent, has been shown to have a possible neuroprotective effect against cerebral ischemia. In addition, chlormethiazole inhibits methamphetamine-induced release of dopamine, protecting against this neurotransmitter's neurotoxicity. The aim of this work was to ascertain whether, in experimental cerebral ischemia, chlormethiazole administration attenuated the ischemia-induced rise of the extracellular concentration of aminergic neurotransmitters and whether it reduces ischemia-induced deficits in memory and learning. Histology for assessment of ischemic damage was a so included. The four-vessel occlusion rat model was used to induce global cerebral ischemia. Aminergic neurotransmitters and their metabolites in the striatal extracellular fluid obtained by microdialysis were assayed by high-performance liquid chromatography-electrochemical detection. The drug was administered either IP (50 mg/kg-1) or directly through the dialysis probe (30 microM) 80 min before ischemia. For the behavioral test and histology, the drug was given IP (100 mg/kg-1) 1 h postischemia. The results obtained did not demonstrate any statistically significant evidence that chlormethiazole has an effect on the ischemia-induced rise in extracellular dopamine and serotonin levels. There was also no variation in metabolite levels. Behavioral measures (learning, recall) were not changed appreciably by the treatment. We observed no significant cell protection in the hippocampus (CA1, CA1), striatum, and entorhinal cortex in animals treated with chlormethiazole. We conclude that, under our experimental conditions, chlormethiazole has little or no effect on the neurochemical, neurobehavioral, and histological consequences of global cerebral ischemia.

Escherichia coli FtsH (HflB) degrades a membrane-associated TolAI-II-beta-lactamase fusion protein under highly denaturing conditions.

PubMed

Cooper, K W; Baneyx, F

2001-03-01

TolAI--II--beta-lactamase, a fusion protein consisting of the inner membrane and transperiplasmic domains of TolA followed by TEM--beta-lactamase associated with the inner membrane but remained confined to the cytoplasm when expressed at high level in Escherichia coli. Although the fusion protein was resistant to proteolysis in vivo, it was hydrolyzed during preparative SDS-polyacrylamide electrophoresis and when insoluble cellular fractions unfolded with 5 M urea were subjected to microdialysis. Inhibitor profiling studies revealed that both a metallo- and serine protease were involved in TolAI--II--beta-lactamase degradation under denaturing conditions. The in vitro degradation rates of the fusion protein were not affected when insoluble fractions were harvested from a strain lacking protease IV, but were significantly reduced when microdialysis experiments were conducted with material isolated from an isogenic ftsH1 mutant. Adenine nucleotides were not required for degradation, and ATP supplementation did not accelerate the apparent rate of TolAI--II--beta-lactamase hydrolysis under denaturing conditions. Our results indicate that the metalloprotease active site of FtsH remains functional in the presence of 3--5 M urea and suggest that the ATPase and proteolytic activities of FtsH can be uncoupled if the substrate is sufficiently unstructured. Thus, a key role of the FtsH AAA module appears to be the net unfolding of bound substrates so that they can be efficiently engaged by the protease active site. Copyright 2001 Academic Press.

Memory Trace Reactivation and Behavioral Response during Retrieval Are Differentially Modulated by Amygdalar Glutamate Receptors Activity: Interaction between Amygdala and Insular Cortex

ERIC Educational Resources Information Center

Osorio-Gómez, Daniel; Guzmán-Ramos, Kioko; Bermúdez-Rattoni, Federico

2017-01-01

The insular cortex (IC) is required for conditioned taste aversion (CTA) retrieval. However, it remains unknown which cortical neurotransmitters levels are modified upon CTA retrieval. Using in vivo microdialysis, we observed that there were clear elevations in extracellular glutamate, norepinephrine, and dopamine in and around the center of the…

Beta-phenylethylamine stimulates striatal acetylcholine release through activation of the AMPA glutamatergic pathway.

PubMed

Ishida, Kota; Murata, Mikio; Kato, Masatoshi; Utsunomiya, Iku; Hoshi, Keiko; Taguchi, Kyoji

2005-09-01

Using an in vivo intra-striatal microdialysis technique, we examined the effects of systemically administered beta-phenylethylamine (beta-PEA), a psychomotor stimulating trace amine, on striatal acetylcholine release in freely moving rats. Infusion of N-methyl-D-aspartic acid (NMDA; 10(-5) M) significantly increased acetylcholine release. In addition, locally applied amino-3-hydroxy-5-methylisozasole-4-propionic acid (AMPA; 10(-5) M) significantly increased acetylcholine release in the striatum. Intra-striatal application of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 10(-5) M), an AMPA-type glutamatergic receptor antagonist, had little effect on acetylcholine release, while application of MK-801 (10(-5) M, 10(-6) M), an NMDA-type glutamatergic receptor antagonist, significantly reduced acetylcholine release. Acetylcholine within striatal perfusate was significantly increased by intraperitoneal administration of beta-PEA in a dose-dependent manner. This increase in acetylcholine release was completely blocked by application of CNQX (10(-5) M) through the microdialysis probe into the striatum. However, increased acetylcholine response to systemic beta-PEA was unaltered by addition of MK-801 to the perfusion medium. These results suggest a regulatory function of beta-PEA, mediated by AMPA-type glutamatergic receptors, on the release of acetylcholine in the rat striatum.

GABA release in the zona incerta of the sheep in response to the sight and ingestion of food and salt.

PubMed

Kendrick, K M; Hinton, M R; Baldwin, B A

1991-05-31

In order to establish which neurotransmitters may influence the activity of zona incerta neurones in the sheep which respond selectively to the sight or ingestion of food, we have measured the release of amino acid and monoamine neurotransmitters from this region using microdialysis sampling. Co-ordinates for the placement of microdialysis probes in regions of the zona incerta where cells respond to the sight or ingestion of food were first established by making single-unit extracellular recordings. When animals were food-deprived results showed that release of gamma-aminobutyric acid (GABA) was increased in response to the sight and ingestion of food but not of aspartate, glutamate, taurine, noradrenaline, dopamine or serotonin. This release of GABA was absent when the animals were shown non-food objects or saw or ingested salt solutions. When the same animals were physiologically sodium-depleted GABA release was evoked by the sight and ingestion of salt solutions and release following the sight and ingestion of food was significantly reduced. These results provide further evidence that GABA is an important neurotransmitter in neural circuits controlling the regulation of food intake.

Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides.

PubMed

Weir, Graeme; Ramage, Lynne E; Akyol, Murat; Rhodes, Jonathan K; Kyle, Catriona J; Fletcher, Alison M; Craven, Thomas H; Wakelin, Sonia J; Drake, Amanda J; Gregoriades, Maria-Lena; Ashton, Ceri; Weir, Nick; van Beek, Edwin J R; Karpe, Fredrik; Walker, Brian R; Stimson, Roland H

2018-06-05

Current understanding of in vivo human brown adipose tissue (BAT) physiology is limited by a reliance on positron emission tomography (PET)/computed tomography (CT) scanning, which has measured exogenous glucose and fatty acid uptake but not quantified endogenous substrate utilization by BAT. Six lean, healthy men underwent 18 fluorodeoxyglucose-PET/CT scanning to localize BAT so microdialysis catheters could be inserted in supraclavicular BAT under CT guidance and in abdominal subcutaneous white adipose tissue (WAT). Arterial and dialysate samples were collected during warm (∼25°C) and cold exposure (∼17°C), and blood flow was measured by 133 xenon washout. During warm conditions, there was increased glucose uptake and lactate release and decreased glycerol release by BAT compared with WAT. Cold exposure increased blood flow, glycerol release, and glucose and glutamate uptake only by BAT. This novel use of microdialysis reveals that human BAT is metabolically active during warm conditions. BAT activation substantially increases local lipolysis but also utilization of other substrates such as glutamate. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Reliable long-term continuous blood glucose monitoring for patients in critical care using microdialysis and infrared spectrometry

NASA Astrophysics Data System (ADS)

Heise, H. Michael; Damm, Uwe; Kondepati, Venkata R.

2006-02-01

For clinical research, in-vivo blood glucose monitoring is an ongoing important topic to improve glycemic control in patients with non-adequate blood glucose regulation. Critically ill patients received much interest, since the intensive insulin therapy treatment, as established for diabetics, reduces mortality significantly. Despite the existence of commercially available, mainly amperometric biosensors, continued interest is in infrared spectroscopic techniques for reagent-free glucose monitoring. For stable long-term operation, avoiding also sensor recalibration, a bed-side device coupled to a micro-dialysis probe was developed for quasi-continuous glucose monitoring. Multivariate calibration is required for glucose concentration prediction due to the complex composition of dialysates from interstitial body fluid. Measurements were carried out with different test persons, each experiment lasting for more than 8 hours. Owing to low dialysis recovery rates, glucose concentrations in the dialysates were between 0.83 and 4.44 mM. Standard errors of prediction (SEP) obtained with Partial Least Squares (PLS) calibration and different cross-validation strategies were mainly between 0.13 and 0.18 mM based on either full interval data or specially selected spectral variables.

Quantification of extracellular levels of corticosterone in the basolateral amygdaloid complex of freely-moving rats: a dialysis study of circadian variation and stress-induced modulation.

PubMed

Bouchez, Gaëlle; Millan, Mark J; Rivet, Jean-Michel; Billiras, Rodolphe; Boulanger, Raphaël; Gobert, Alain

2012-05-03

Corticosterone influences emotion and cognition via actions in a diversity of corticolimbic structures, including the amygdala. Since extracellular levels of corticosterone in brain have rarely been studied, we characterized a specific and sensitive enzymatic immunoassay for microdialysis quantification of corticosterone in the basolateral amygdaloid complex of freely-moving rats. Corticosterone levels showed marked diurnal variation with an evening (dark phase) peak and stable, low levels during the day (light phase). The "anxiogenic agents", FG7142 (20 mg/kg) and yohimbine (10 mg/kg), and an environmental stressor, 15-min forced-swim, induced marked and sustained (1-3 h) increases in dialysis levels of corticosterone in basolateral amygdaloid complex. They likewise increased dialysis levels of dopamine and noradrenaline, but not serotonin and GABA. As compared to basal corticosterone levels of ~200-300 pg/ml, the elevation provoked by forced-swim was ca. 20-fold and this increase was abolished by adrenalectomy. Interestingly, stress-induced rises of corticosterone levels in basolateral amygdaloid complex were abrogated by combined but not separate administration of the corticotrophin releasing factor(1) (CRF(1)) receptor antagonist, CP154,526, and the vasopressin(1b) (V(1b)) receptor antagonist, SSR149,415. Underpinning their specificity, they did not block forced-swim-induced elevations in dopamine and noradrenaline. In conclusion, extracellular levels of corticosterone in the basolateral amygdaloid complex display marked diurnal variation. Further, they are markedly elevated by acute stressors, the effects of which are mediated (in contrast to concomitant elevations in levels of monoamines) by co-joint recruitment of CRF(1) and V(1b) receptors. Copyright © 2012 Elsevier B.V. All rights reserved.

Comprehensive behavioral study of mGluR3 knockout mice: implication in schizophrenia related endophenotypes

PubMed Central

2014-01-01

Background We previously performed systematic association studies of glutamate receptor gene family members with schizophrenia, and found positive associations of polymorphisms in the GRM3 (a gene of metabotropic glutamate receptor 3: mGluR3) with the disorder. Physiological roles of GRM3 in brain functions and its functional roles in the pathogenesis of schizophrenia remain to be resolved. Results We generated mGluR3 knockout (KO) mice and conducted comprehensive behavioral analyses. KO mice showed hyperactivity in the open field, light/dark transition, and 24-hour home cage monitoring tests, impaired reference memory for stressful events in the Porsolt forced swim test, impaired contextual memory in cued and contextual fear conditioning test, and impaired working memory in the T-Maze forced alternation task test. Hyperactivity and impaired working memory are known as endophenotypes of schizophrenia. We examined long-term synaptic plasticity by assessing long-term potentiation (LTP) in the CA1 region in the hippocampi of KO and wild-type (WT) mice. We observed no differences in the amplitude of LTP between the two genotypes, suggesting that mGluR3 is not essential for LTP in the CA1 region of the mouse hippocampus. As hyperactivity is typically associated with increased dopaminergic transmission, we performed in vivo microdialysis measurements of extracellular dopamine in the nucleus accumbens of KO and WT mice. We observed enhancements in the methamphetamine (MAP)-induced release of dopamine in KO mice. Conclusions These results demonstrate that a disturbance in the glutamate-dopamine interaction may be involved in the pathophysiology of schizophrenia-like behavior, such as hyperactivity in mGluR3 KO mice. PMID:24758191

[The effects of lesions in the compact part of the substantia nigra on glutamate and GABA release in the pedunculopontine nucleus].

PubMed

Blanco-Lezcano, L; Rocha-Arrieta, L L; Alvarez-González, L; Martínez-Martí, L; Pavón-Fuentes, N; González-Fraguela, M E; Bauzá-Calderín, Y; Coro-Grave de Peralta, Y

The pedunculopontine nucleus (PPN), co-localized with the mesencephalic locomotor region, has been proposed as a key structure in the physiopathology of Parkinson's disease. The goal of the present study was to assess if the aminoacid neurotransmitter release in the PPN is modified by the degeneration of dopaminergic cells, from substantia nigra pars compacta in 6-hydroxidopamine (6-OHDA)-lesioned rats. In addition, it was studied the aminoacid neurotransmitter release in the PPN of rats with lesion of the subthalamic nucleus by quinolinic acid (QUIN) (100 nmol) intracerebral injection. Rats were assigned to five groups: untreated rats (I) (n = 13), 6-OHDA lesion (II) (n = 11), 6-OHDA + QUIN lesion (III) (n = 9), sham-operated (IV) (n = 10), QUIN, STN (V) lesioned (n = 9). The extracellular concentrations of glutamic acid (GLU) and gamma-aminobutyric acid (GABA) were determined by brain microdialysis and high performance liquid chromatography (HPLC). RESULTS. GLU released in PPN from 6-OHDA lesioned rats (group II), was significantly increased in comparison with the others groups (F(4, 47) = 18.21, p < 0.001). GABA released shows significant differences between experimental groups (F(4, 45) = 12.75, p < 0.001). It was detected a higher valour (p < 0.05) in-group II. The groups III and IV exhibited intermeddle valour (p < 0.001) and groups I and IV (p < 0.001) showed the lower GABA extracellular concentrations. The infusion of artificial cerebrospinal fluid with higher potassium (100 mmol) induced an increase in the GLU and GABA released in all groups, which confirm the neuronal origin of the extracellular content. These results are in agreement with the current model of basal ganglia functioning and suggest the role of STN-PPN projection in the physiopathology of Parkinson's disease.

18-Methoxycoronaridine Blocks Context-induced Reinstatement Following Cocaine Self-administration in Rats

PubMed Central

Polston, J.E.; Pritchett, C.E.; Sell, E.M.; Glick, S.D.

2012-01-01

Numerous studies utilizing drug self-administration have shown the importance of conditioned cues in maintaining and reinstating addictive behaviors. However, most used simple cues that fail to replicate the complexity of cues present in human craving and addiction. We have recently shown that music can induce behavioral and neurochemical changes in rats following classical conditioning with psychostimulants. However, such effects have yet to be characterized utilizing operant self-administration procedures, particularly with regard to craving and relapse. The goal of the present study was to validate the effectiveness of music as a contextual conditioned stimulus using cocaine in an operant reinstatement model of relapse. Rats were trained to lever press for cocaine with a musical cue, and were subsequently tested during reinstatement sessions to determine how musical conditioning affected drug seeking behavior. Additionally, in vivo microdialysis was used to determine basolateral amygdala involvement during reinstatement. Lastly, tests were conducted to determine whether the putative anti-addictive agent 18-methoxycoronaridine (18-MC) could attenuate cue-induced drug seeking behavior. Our results show that music-conditioned animals exhibited increased drug seeking behaviors when compared to controls during reinstatement test sessions. Furthermore, music-conditioned subjects exhibited increased extracellular dopamine in the basolateral amygdala during reinstatement sessions. Perhaps most importantly, 18-MC blocked musical cue-induced reinstatement. Thus, music can be a powerful contextual conditioned cue in rats, capable of inducing changes in both brain neurochemistry and drug seeking behavior during abstinence. The fact that 18-MC blocked cue-induced reinstatement suggests that α3β4 nicotinic receptors may be involved in the mechanism of craving, and that 18-MC may help prevent relapse to drug addiction in humans. PMID:22885280

Microvascular Endothelial Dysfunction in Sedentary, Obese Humans is mediated by NADPH Oxidase; Influence of Exercise Training

PubMed Central

La Favor, Justin D.; Dubis, Gabriel S.; Yan, Huimin; White, Joseph D.; Nelson, Margaret A.M.; Anderson, Ethan J.; Hickner, Robert C.

2016-01-01

Objective The objectives of this study were to determine the impact of in vivo reactive oxygen species (ROS) on microvascular endothelial function in obese human subjects and to determine the efficacy of an aerobic exercise intervention on alleviating obesity-associated dysfunctionality. Approach and Results Young, sedentary men and women were divided into lean (BMI 18–25; n=14), intermediate (BMI 28–32.5; n=13), and obese (BMI 33–40; n=15) groups. A novel microdialysis technique was utilized to detect elevated interstitial hydrogen peroxide (H2O2) and superoxide levels in the vastus lateralis of obese compared to both lean and intermediate subjects. Nutritive blood flow was monitored in the vastus lateralis via the microdialysis-ethanol technique. A decrement in acetylcholine-stimulated blood flow revealed impaired microvascular endothelial function in the obese subjects. Perfusion of apocynin, an NADPH oxidase (Nox) inhibitor, lowered (normalized) H2O2 and superoxide levels and reversed microvascular endothelial dysfunction in obese subjects. Following 8-weeks of exercise, H2O2 levels were decreased in the obese subjects and microvascular endothelial function in these subjects was restored to levels similar to lean subjects. Skeletal muscle protein expression of the Nox subunits p22phox, p47phox, and p67phox were increased in obese relative to lean subjects, where p22phox and p67phox expression was attenuated by exercise training in obese subjects. Conclusions This study implicates Nox as a source of excessive ROS production in skeletal muscle of obese individuals, and links excessive Nox derived ROS to microvascular endothelial dysfunction in obesity. Furthermore, aerobic exercise training proved to be an effective strategy for alleviating these maladies. PMID:27765769

Alteration in plasma and striatal levels of d-serine after d-serine administration with or without nicergoline: An in vivo microdialysis study.

PubMed

Onozato, Mayu; Nakazawa, Hiromi; Ishimaru, Katsuyuki; Nagashima, Chihiro; Fukumoto, Minori; Hakariya, Hitomi; Sakamoto, Tatsuya; Ichiba, Hideaki; Fukushima, Takeshi

2017-09-01

d-Serine (d-Ser), a co-agonist of N -methyl-d-aspartate receptor (NMDAR), is effective for treating schizophrenia. The present study investigated changes in plasma and striatal d-Ser levels in Sprague-Dawley (SD) rats after intraperitoneal d-Ser administration alone or together with nicergoline (Nic), a commercial cerebral ameliorating drug, using in vivo microdialysis (MD) to explore the function of Nic. Phosphate-buffered saline (PBS) or Nic (0, 1.0, or 3.0 mg/kg) followed by d-Ser (5.0, 10.0, 20.0, and 50.0 mg/kg for PBS or 20.0 mg/kg for Nic) was administered intraperitoneally to male SD rats, and the profiles of d-Ser levels in plasma and striatal MD samples were examined by high-performance liquid chromatography (HPLC) with fluorescence detection. The area under the curve (AUC) for the MD and plasma samples was also calculated and statistically compared among groups. AUC values of d-Ser increased in a d-Ser dose-dependent manner in plasma samples, while a proportional increase in the AUC values of striatal MD samples was only observed in d-Ser doses up to 20 mg/kg. The Nic co-administered group showed a significant increase in the AUC of plasma d-Ser in a Nic dose-dependent manner, but the AUC in striatal d-Ser significantly decreased with increasing Nic doses suggesting that Nic may prevent excess d-Ser from penetrating the central nervous system (CNS). Nic may prevent an excessive distribution of exogenous d-Ser, such as that from a dietary origin, into the CNS by suppressing excitatory neurotransmission through NMDAR.

Response of brain oxygenation and metabolism to deep hypothermic circulatory arrest in newborn piglets: comparison of pH-stat and alpha-stat strategies.

PubMed

Markowitz, Scott D; Mendoza-Paredes, Alberto; Liu, Huiping; Pastuszko, Peter; Schultz, Steven P; Schears, Gregory J; Greeley, William J; Wilson, David F; Pastuszko, Anna

2007-07-01

To determine the effect of pH-stat as compared with alpha-stat management on brain oxygenation, level of striatal extracellular dopamine, phosphorylation, and levels of protein kinase B (Akt) and cyclic adenosine 3', 5'-monophosphate response element-binding protein (CREB), and levels of extracellular signal-regulated kinase (ERK)1/2, Bcl-2, and Bax in a piglet model of deep hypothermic circulatory arrest (DHCA). The piglets were placed on cardiopulmonary bypass (CPB), cooled with pH-stat or alpha-stat to 18 degrees C, subjected to 90 minutes of DHCA, rewarmed, weaned from CPB, and maintained for two hours recovery. The cortical oxygen was measured by: quenching of phosphorescence; dopamine by microdialysis; phosphorylation of CREB (p-CREB), ERK (p-ERK) 1/2, Akt (p-Akt), and level of Bcl-2, Bax by Western blots. Oxygen pressure histograms for the microvasculature of the cortex show substantially higher oxygen levels during cooling and during the oxygen depletion period after cardiac arrest (up to 15 minutes) when using pH-stat compared with alpha-stat management. Significant increases in dopamine occurred at 45 minutes and 60 minutes of DHCA in the alpha-stat and pH-stat groups, respectively. The p-CREB and p-Akt in the pH-stat group were significantly higher than in the alpha-stat group (140 +/- 9%, p < 0.05 and 125 +/- 6%, p < 0.05, respectively). There was no significant difference in p-ERK1/2 and Bax. The Bcl-2 increased in the pH-stat group to 121 +/- 4% (p < 0.05) compared with the alpha-stat group. The ratio Bcl-2:Bax increased in the pH-stat group compared with the alpha-stat group. The increase in p-CREB, p-Akt, Bcl-2, Bcl-2/Bax, and delay in increase of dopamine indicated that pH-stat, in the piglet model, prolongs "safe" time of DHCA and provides some brain protection against ischemic injury.

Deriving Therapies for Children with Primary CNS Tumors Using Pharmacokinetic Modeling and Simulation of Cerebral Microdialysis Data

PubMed Central

Jacus, M.O.; Throm, S.L.; Turner, D.C.; Patel, Y.T.; Freeman, B.B.; Morfouace, M.; Boulos, N.; Stewart, C. F.

2014-01-01

The treatment of children with primary central nervous system (CNS) tumors continues to be a challenge despite recent advances in technology and diagnostics. In this overview, we describe our approach for identifying and evaluating active anticancer drugs through a process that enables rational translation from the lab to the clinic. The preclinical approach we discuss uses tumor subgroup-specific models of pediatric CNS tumors, cerebral microdialysis sampling of tumor extracellular fluid (tECF), and pharmacokinetic modeling and simulation to overcome challenges that currently hinder researchers in this field. This approach involves performing extensive systemic (plasma) and target site (CNS tumor) pharmacokinetic studies. Pharmacokinetic modeling and simulation of the data derived from these studies are then used to inform future decisions regarding drug administration, including dosage and schedule. Here, we also present how our approach was used to examine two FDA approved drugs, simvastatin and pemetrexed, as candidates for new therapies for pediatric CNS tumors. We determined that due to unfavorable pharmacokinetic characteristics and insufficient concentrations in tumor tissue in a mouse model of ependymoma, simvastatin would not be efficacious in further preclinical trials. In contrast to simvastatin, pemetrexed was advanced to preclinical efficacy studies after our studies determined that plasma exposures were similar to those in humans treated at similar tolerable dosages and adequate unbound concentrations were found in tumor tissue of medulloblastoma-bearing mice. Generally speaking, the high clinical failure rates for CNS drug candidates can be partially explained by the fact that therapies are often moved into clinical trials without extensive and rational preclinical studies to optimize the transition. Our approach addresses this limitation by using pharmacokinetic and pharmacodynamic modeling of data generated from appropriate in vivo models to support the rational testing and usage of innovative therapies in children with CNS tumors. PMID:24269626

Roles of p75NTR, long-term depression and cholinergic transmission in anxiety and acute stress coping

PubMed Central

Martinowich, Keri; Schloesser, Robert J.; Lu, Yuan; Jimenez, Dennisse V.; Paredes, Daniel; Greene, Joshua S.; Greig, Nigel H.; Manji, Husseini K.; Lu, Bai

2011-01-01

Background Stress is causally associated with anxiety. While the underlying cellular mechanisms are not well understood, the basal forebrain cholinergic neurons (BFCNs) have been implicated in stress response. p75NTR is a pan-neurotrophin receptor expressed almost exclusively in BFCNs in adult brain. The present study investigates whether and how p75NTR, via regulation of the cholinergic system and hippocampal synaptic plasticity, influences stress-related behaviors. Methods We used a combination of slice electrophysiology, behavioral analyses, pharmacology, in vivo microdialysis and neuronal activity mapping to assess the role of p75NTR in mood and stress-related behaviors and its underlying cellular and molecular mechanisms. Results We show that acute stress enables hippocampal long-term depression (LTD) in adult wild-type mice, but not in mice lacking p75NTR. The p75NTR mutant mice also exhibit two distinct behavioral impairments: baseline anxiety-like behavior and a deficit in coping with and recovering from stressful situations. Blockade of stress-enabled LTD with a GluA2-derived peptide impaired stress recovery without affecting baseline anxiety. Pharmacological manipulations of cholinergic transmission mimicked the p75NTR perturbation in both baseline anxiety and responses to acute stress. Finally, we show evidence of misregulated cholinergic signaling in animals with p75NTR deletion. Conclusions Our results suggest that loss of p75NTR leads to changes in hippocampal cholinergic signaling, which may be involved in regulation of stress-enabled hippocampal LTD and in modulating behaviors related to stress and anxiety. PMID:21978521

Mu opioid receptors in GABAergic forebrain neurons moderate motivation for heroin and palatable food

PubMed Central

Charbogne, Pauline; Gardon, Olivier; Martín-García, Elena; Keyworth, Helen L.; Matsui, Aya; Mechling, Anna E.; Bienert, Thomas; Nasseef, Taufiq; Robé, Anne; Moquin, Luc; Darcq, Emmanuel; Ben Hamida, Sami; Robledo, Patricia; Matifas, Audrey; Befort, Katia; Gavériaux-Ruff, Claire; Harsan, Laura-Adela; Von Everfeldt, Dominik; Hennig, Jurgen; Gratton, Alain; Kitchen, Ian; Bailey, Alexis; Alvarez, Veronica A.; Maldonado, Rafael; Kieffer, Brigitte L.

2016-01-01

BACKGROUND Mu opioid receptors (MORs) are central to pain control, drug reward and addictive behaviors, but underlying circuit mechanisms have been poorly explored by genetic approaches. Here we investigate the contribution of MORs expressed in GABAergic forebrain neurons to major biological effects of opiates, and also challenge the canonical disinhibition model of opiate reward. METHODS We used Dlx5/6-mediated recombination to create conditional Oprm1 mice in GABAergic forebrain neurons. We characterized the genetic deletion by histology, electrophysiology and microdialysis, probed neuronal activation by c-Fos immunohistochemistry and resting state-functional magnetic resonance imaging, and investigated main behavioral responses to opiates, including motivation to obtain heroin and palatable food. RESULTS Mutant mice showed MOR transcript deletion mainly in the striatum. In the ventral tegmental area (VTA), local MOR activity was intact, and reduced activity was only observed at the level of striatonigral afferents. Heroin-induced neuronal activation was modified at both sites, and whole-brain functional networks were altered in live animals. Morphine analgesia was not altered, neither was physical dependence to chronic morphine. In contrast, locomotor effects of heroin were abolished, and heroin-induced catalepsy was increased. Place preference to heroin was not modified, but remarkably, motivation to obtain heroin and palatable food was enhanced in operant self-administration procedures. CONCLUSIONS Our study reveals dissociable MOR functions across mesocorticolimbic networks. Thus beyond a well-established role in reward processing, operating at the level of local VTA neurons, MORs also moderate motivation for appetitive stimuli within forebrain circuits that drive motivated behaviors. PMID:28185645

Striatal dysfunction increases basal ganglia output during motor cortex activation in parkinsonian rats.

PubMed

Belluscio, Mariano A; Riquelme, Luis A; Murer, M Gustavo

2007-05-01

During movement, inhibitory neurons in the basal ganglia output nuclei show complex modulations of firing, which are presumptively driven by corticostriatal and corticosubthalamic input. Reductions in discharge should facilitate movement by disinhibiting thalamic and brain stem nuclei while increases would do the opposite. A proposal that nigrostriatal dopamine pathway degeneration disrupts trans-striatal pathways' balance resulting in sustained overactivity of basal ganglia output nuclei neurons and Parkinson's disease clinical signs is not fully supported by experimental evidence, which instead shows abnormal synchronous oscillatory activity in animal models and patients. Yet, the possibility that variation in motor cortex activity drives transient overactivity in output nuclei neurons in parkinsonism has not been explored. In Sprague-Dawley rats with 6-hydroxydopamine (6-OHDA)-induced nigrostriatal lesions, approximately 50% substantia nigra pars reticulata (SNpr) units show abnormal cortically driven slow oscillations of discharge. Moreover, these units selectively show abnormal responses to motor cortex stimulation consisting in augmented excitations of an odd latency, which overlapped that of inhibitory responses presumptively mediated by the trans-striatal direct pathway in control rats. Delivering D1 or D2 dopamine agonists into the striatum of parkinsonian rats by reverse microdialysis reduced these abnormal excitations but had no effect on pathological oscillations. The present study establishes that dopamine-deficiency related changes of striatal function contribute to producing abnormally augmented excitatory responses to motor cortex stimulation in the SNpr. If a similar transient overactivity of basal ganglia output were driven by motor cortex input during movement, it could contribute to impeding movement initiation or execution in Parkinson's disease.

α1-Adrenoceptors in the hippocampal dentate gyrus involved in learning-dependent long-term potentiation during active-avoidance learning in rats.

PubMed

Lv, Jing; Zhan, Su-Yang; Li, Guang-Xie; Wang, Dan; Li, Ying-Shun; Jin, Qing-Hua

2016-11-09

The hippocampus is the key structure for learning and memory in mammals and long-term potentiation (LTP) is an important cellular mechanism responsible for learning and memory. The influences of norepinephrine (NE) on the modulation of learning and memory, as well as LTP, through β-adrenoceptors are well documented, whereas the role of α1-adrenoceptors in learning-dependent LTP is not yet clear. In the present study, we measured extracellular concentrations of NE in the hippocampal dentate gyrus (DG) region using an in-vivo brain microdialysis and high-performance liquid chromatography techniques during the acquisition and extinction of active-avoidance behavior in freely moving conscious rats. Next, the effects of prazosin (an antagonist of α1-adrenoceptor) and phenylephrine (an agonist of the α1-adrenoceptor) on amplitudes of field excitatory postsynaptic potential were measured in the DG region during the active-avoidance behavior. Our results showed that the extracellular concentration of NE in the DG was significantly increased during the acquisition of active-avoidance behavior and gradually returned to the baseline level following extinction training. A local microinjection of prazosin into the DG significantly accelerated the acquisition of the active-avoidance behavior, whereas a local microinjection of phenylephrine retarded the acquisition of the active-avoidance behavior. Furthermore, in all groups, the changes in field excitatory postsynaptic potential amplitude were accompanied by corresponding changes in active-avoidance behavior. Our results suggest that NE activation of α1-adrenoceptors in the hippocampal DG inhibits active-avoidance learning by modulation of synaptic efficiency in rats.

Neurochemical and Neurotoxic Effects of MDMA (Ecstasy) and Caffeine After Chronic Combined Administration in Mice.

PubMed

Górska, Anna Maria; Kamińska, Katarzyna; Wawrzczak-Bargieła, Agnieszka; Costa, Giulia; Morelli, Micaela; Przewłocki, Ryszard; Kreiner, Grzegorz; Gołembiowska, Krystyna

2018-04-01

MDMA (3,4-methylenedioxymethamphetamine) is a psychostimulant popular as a recreational drug because of its effect on mood and social interactions. MDMA acts at dopamine (DA) transporter (DAT) and serotonin (5-HT) transporter (SERT) and is known to induce damage of dopamine and serotonin neurons. MDMA is often ingested with caffeine. Caffeine as a non-selective adenosine A1/A2A receptor antagonist affects dopaminergic and serotonergic transmissions. The aim of the present study was to determine the changes in DA and 5-HT release in the mouse striatum induced by MDMA and caffeine after their chronic administration. To find out whether caffeine aggravates MDMA neurotoxicity, the content of DA and 5-HT, density of brain DAT and SERT, and oxidative damage of nuclear DNA were determined. Furthermore, the effect of caffeine on MDMA-induced changes in striatal dynorphin and enkephalin and on behavior was assessed. The DA and 5-HT release was determined with in vivo microdialysis, and the monoamine contents were measured by HPLC with electrochemical detection. DNA damage was assayed with the alkaline comet assay. DAT and SERT densities were determined by immunohistochemistry, while prodynorphin (PDYN) and proenkephalin were determined by quantitative PCR reactions. The behavioral changes were measured by the open-field (OF) test and novel object recognition (NOR) test. Caffeine potentiated MDMA-induced DA release while inhibiting 5-HT release in the mouse striatum. Caffeine also exacerbated the oxidative damage of nuclear DNA induced by MDMA but diminished DAT decrease in the striatum and worsened a decrease in SERT density produced by MDMA in the frontal cortex. Neither the striatal PDYN expression, increased by MDMA, nor exploratory and locomotor activities of mice, decreased by MDMA, were affected by caffeine. The exploration of novel object in the NOR test was diminished by MDMA and caffeine. Our data provide evidence that long-term caffeine administration has a powerful influence on functions of dopaminergic and serotonergic neurons in the mouse brain and on neurotoxic effects evoked by MDMA.

In vitro and in vivo characterization of JNJ-31020028 (N-(4-{4-[2-(diethylamino)-2-oxo-1-phenylethyl]piperazin-1-yl}-3-fluorophenyl)-2-pyridin-3-ylbenzamide), a selective brain penetrant small molecule antagonist of the neuropeptide Y Y(2) receptor.

PubMed

Shoblock, James R; Welty, Natalie; Nepomuceno, Diane; Lord, Brian; Aluisio, Leah; Fraser, Ian; Motley, S Timothy; Sutton, Steve W; Morton, Kirsten; Galici, Ruggero; Atack, John R; Dvorak, Lisa; Swanson, Devin M; Carruthers, Nicholas I; Dvorak, Curt; Lovenberg, Timothy W; Bonaventure, Pascal

2010-02-01

The lack of potent, selective, brain penetrant Y(2) receptor antagonists has hampered in vivo functional studies of this receptor. Here, we report the in vitro and in vivo characterization of JNJ-31020028 (N-(4-{4-[2-(diethylamino)-2-oxo-1-phenylethyl]piperazin-1-yl}-3-fluorophenyl)-2-pyridin-3-ylbenzamide), a novel Y(2) receptor antagonist. The affinity of JNJ-31020028 was determined by inhibition of the PYY binding to human Y(2) receptors in KAN-Ts cells and rat Y(2) receptors in rat hippocampus. The functional activity was determined by inhibition of PYY-stimulated calcium responses in KAN-Ts cells expressing a chimeric G protein Gqi5 and in the rat vas deferens (a prototypical Y(2) bioassay). Ex vivo receptor occupancy was revealed by receptor autoradiography. JNJ-31020028 was tested in vivo with microdialysis, in anxiety models, and on corticosterone release. JNJ-31020028 bound with high affinity (pIC(50) = 8.07 +/- 0.05, human, and pIC(50) = 8.22 +/- 0.06, rat) and was >100-fold selective versus human Y(1), Y(4), and Y(5) receptors. JNJ-31020028 was demonstrated to be an antagonist (pK(B) = 8.04 +/- 0.13) in functional assays. JNJ-31020028 occupied Y(2) receptor binding sites (approximately 90% at 10 mg/kg) after subcutaneous administration in rats. JNJ-31020028 increased norepinephrine release in the hypothalamus, consistent with the colocalization of norepinephrine and neuropeptide Y. In a variety of anxiety models, JNJ-31020028 was found to be ineffective, although it did block stress-induced elevations in plasma corticosterone, without altering basal levels, and normalized food intake in stressed animals without affecting basal food intake. These results suggest that Y(2) receptors may not be critical for acute behaviors in rodents but may serve modulatory roles that can only be elucidated under specific situational conditions.

Metabotropic Glutamate Receptor 7 Modulates the Rewarding Effects of Cocaine in Rats: Involvement of a Ventral Pallidal GABAergic Mechanism

PubMed Central

Li, Xia; Li, Jie; Peng, Xiao-Qing; Spiller, Krista; Gardner, Eliot L; Xi, Zheng-Xiong

2013-01-01

The metabotropic glutamate receptor 7 (mGluR7) has received much attention as a potential target for the treatment of epilepsy, major depression, and anxiety. In this study, we investigated the possible involvement of mGluR7 in cocaine reward in animal models of drug addiction. Pretreatment with the selective mGluR7 allosteric agonist N,N’-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082; 1-20 mg/kg, i.p.) dose-dependently inhibited cocaine-induced enhancement of electrical brain-stimulation reward and intravenous cocaine self-administration under both fixed-ratio and progressive-ratio reinforcement conditions, but failed to alter either basal or cocaine-enhanced locomotion or oral sucrose self-administration, suggesting a specific inhibition of cocaine reward. Microinjections of AMN082 (1–5 μg/μl per side) into the nucleus accumbens (NAc) or ventral pallidum (VP), but not dorsal striatum, also inhibited cocaine self-administration in a dose-dependent manner. Intra-NAc or intra-VP co-administration of 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazolo[4,5-c]pyridin-4(5H)-one (MMPIP, 5 μg/μl per side), a selective mGluR7 allosteric antagonist, significantly blocked AMN082’s action, suggesting an effect mediated by mGluR7 in these brain regions. In vivo microdialysis demonstrated that cocaine (10 mg/kg, i.p.) priming significantly elevated extracellular DA in the NAc or VP, while decreasing extracellular GABA in VP (but not in NAc). AMN082 pretreatment selectively blocked cocaine-induced changes in extracellular GABA, but not in DA, in both naive rats and cocaine self-administration rats. These data suggest: (1) mGluR7 is critically involved in cocaine’s acute reinforcement; (2) GABA-, but not DA-, dependent mechanisms in the ventral striatopallidal pathway appear to underlie AMN082’s actions; and (3) AMN082 or other mGluR7-selective agonists may be useful in the treatment of cocaine addiction. PMID:19158667

The Sigma-2 Receptor Selective Agonist Siramesine (Lu 28-179) Decreases Cocaine-Reinforced Pavlovian Learning and Alters Glutamatergic and Dopaminergic Input to the Striatum

PubMed Central

Klawonn, Anna M.; Nilsson, Anna; Rådberg, Carl F.; Lindström, Sarah H.; Ericson, Mia; Granseth, Björn; Engblom, David; Fritz, Michael

2017-01-01

Drug addiction is a chronic, debilitating disease that affects millions of people around the world causing a substantial societal burden. Despite decades of research efforts, treatment possibilities remain limited and relapse represents the most treatment-resistant element. Neurosteroid sigma-1 receptors have been meticulously studied in psychostimulant reinforced Pavlovian learning, while the sigma-2 receptor subtype has remained unexplored. Recent development of selective sigma-2 receptor ligands have now made it possible to investigate if the sigma-2 receptor system is a potential target to treat drug addiction. We examined the effect of the sigma-2 receptor agonist Siramesine (Lu 28-179) on cocaine-associated locomotion, Pavlovian learning, and reward neurocircuitry using electrophysiology recordings and in vivo microdialysis. We found that Siramesine significantly attenuated conditioned place preference acquisition and expression, as well as it completely blocked cocaine-primed reinstatement. Siramesine, in a similar manner as the selective sigma-1 receptor antagonist BD 1063, decreased acute locomotor responses to cocaine. Immunohistochemistry suggests co-expression of progesterone receptor membrane component 1/sigma-2 receptors and vesicular glutamate transporter 1 in presynaptic boutons of the nucleus accumbens (NAc). Whole-cell voltage clamp recordings of neurons in the NAc indicated that Siramesine decreases the presynaptic release probability of glutamate. Further, we demonstrated, via in vivo microdialysis, that Siramesine significantly decreased cocaine-evoked dopamine release in the striatum of freely moving mice. Collectively, these findings demonstrate that sigma-2 receptors regulate neurocircuitry responsible for positive reinforcement and thereby play a role in cocaine-reinforced Pavlovian behaviors. PMID:29066971

Is early detection of anastomotic leakage possible by intraperitoneal microdialysis and intraperitoneal cytokines after anterior resection of the rectum for cancer?

PubMed

Matthiessen, Peter; Strand, Ida; Jansson, Kjell; Törnquist, Cathrine; Andersson, Magnus; Rutegård, Jörgen; Norgren, Lars

2007-11-01

This prospective study assessed methods of detecting intraperitoneal ischemia and inflammatory response in patients with and without postoperative complications after anterior resection of the rectum. In 23 patients operated on with anterior resection of the rectum for rectal carcinoma, intraperitoneal lactate, pyruvate, and glucose levels were monitored postoperatively for six days by using microdialysis with catheters applied in two locations: intraperitoneally near the anastomosis, and in the central abdominal cavity. A reference catheter was placed subcutaneously in the pectoral region. Cytokines, interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha, were measured in intraperitoneal fluid by means of a pelvic drain for two postoperative days. The intraperitoneal lactate/pyruvate ratio near the anastomosis was higher on postoperative Day 5 (P = 0.029) and Day 6 (P = 0.009) in patients with clinical anastomotic leakage (n = 7) compared with patients without leakage (n = 16). The intraperitoneal levels of IL-6 (P = 0.002; P = 0.012, respectively) and IL-10 (P = 0.002; P = 0.041, respectively) were higher on postoperative Days 1 and 2 in the leakage group, and TNF-alpha was higher in the leakage group on Day 1 (P = 0.011). In-hospital clinical anastomotic leakage was diagnosed on median Day 6, and leakage after hospital discharge on median Day 20. The intraperitoneal lactate/pyruvate ratio and cytokines, IL-6, IL-10, and TNF-alpha, were increased in patients who developed symptomatic anastomotic leakage before clinical symptoms were evident.

Development of a simultaneous PET/microdialysis method to identify the optimal dose of 11C-raclopride for small animal imaging

PubMed Central

Schiffer, Wynne K.; Alexoff, David L.; Shea, Colleen; Logan, Jean; Dewey, Stephen L.

2005-01-01

In the field of small animal positron emission tomography (PET), the assumptions underlying human and primate kinetic models may not be sustained in rodents. That is, the threshold dose at which a pharmacologic response occurs may be lower in small animals. In order to define this relationship, we combined microPET imaging using 11C-raclopride with microdialysis measures of extracellular fluid (ECF) dopamine (DA). In addition, we performed a series of studies in which a known mass of raclopride was microinfused into one striatum prior to a high specific activity (SA) systemic injection of 11C-raclopride. This single-injection approach provided a high and low SA region of radiotracer binding in the same animal during the same scanning session. Our data demonstrate that the binding potential (BP) declines above 3.5 pmol/ml (0.35 μg), with an ED50 of 8.55 ± 5.62 pmol/ml. These data also provide evidence that BP may be compromised by masses of raclopride below 2.0 pmol/ml (0.326 μg). Increases in ECF DA were produced by mass doses of raclopride over 3.9 pmol/ml (0.329 μg) with an ED50 of 8.53 ± 2.48 pmol/ml. Taken together, it appears that an optimal range of raclopride mass exists between 2.0 and 3.5 pmol/ml, around which the measured BP can be compromised by system sensitivity, endogenous DA, or excessive competition with unlabeled compound. PMID:15848236

The HIV-1 associated protein, Tat1–86, impairs dopamine transporters and interacts with cocaine to reduce nerve terminal function: a no-net-flux microdialysis study

PubMed Central

Ferris, Mark J.; Frederick-Duus, Danielle; Fadel, Jim; Mactutus, Charles F.; Booze, Rosemarie M.

2009-01-01

Injection drug use accounts for approximately one-third of HIV-infections in the United States. HIV associated proteins have been shown to interact with various drugs of abuse to incite concerted neurotoxicity. One common area for their interaction is the nerve terminal, including dopamine transporter (DAT) systems. However, results regarding DAT function and regulation in HIV-infection, regardless of drug use, are mixed. Thus, the present experiments were designed to explicitly control Tat and cocaine administration in an in vivo model in order to reconcile differences that exist in the literature to date. We examined Tat plus cocaine-induced alterations using no-net-flux microdialysis, which is sensitive to alterations in DAT function, in order to test the potential for DAT as an early mediator of HIV-induced oxidative stress and neurodegeneration in vivo. Within 5 hours of intra-accumbal administration of the HIV-associated protein, Tat, we noted a significant reduction in local DAT efficiency with little change in DA overflow/release dynamics. Further, at 48 hrs post-Tat administration, we demonstrated a concerted effect of the HIV-protein Tat with cocaine on both uptake and release function. Finally, we discuss the extent to which DAT dysfunction may be considered a predecessor to generalized nerve terminal dysfunction. Characterization of DAT dysfunction in vivo may provide an early pharamacotherapeutic target, which in turn may prevent or attenuate downstream mediators of neurotoxicity (i.e., reactive species) to DA systems occurring in NeuroAIDS. PMID:19344635

The GABA uptake inhibitor beta-alanine reduces pilocarpine-induced tremor and increases extracellular GABA in substantia nigra pars reticulata as measured by microdialysis.

PubMed

Ishiwari, Keita; Mingote, Susana; Correa, Merce; Trevitt, Jennifer T; Carlson, Brian B; Salamone, John D

2004-12-30

Substantia nigra pars reticulata (SNr) is a major output nucleus of the basal ganglia that receives GABAergic projections from neostriatum and globus pallidus. Previous research has shown that local pharmacological manipulations of GABA in SNr can influence tremulous jaw movements in rats. Tremulous jaw movements are defined as rapid vertical deflections of the lower jaw that resemble chewing but are not directed at a particular stimulus, and evidence indicates that these movements share many characteristics with parkinsonian tremor in humans. In order to investigate the role of GABA in motor functions related to tremor, the present study tested the GABA uptake blocker beta-alanine for its ability to reduce pilocarpine-induced tremulous jaw movements. In a parallel experiment, the effect of an active dose of beta-alanine on dialysate levels of GABA in SNr was assessed using microdialysis methods. GABA levels in dialysis samples were measured using high performance liquid chromatography with electrochemical detection. beta-Alanine (250-500 mg/kg) significantly reduced tremulous jaw movements induced by pilocarpine (4.0 mg/kg). Moreover, systemic administration of beta-alanine at a dose that reduced tremulous jaw movements (500 mg/kg) resulted in a substantial increase in extracellular levels of GABA in SNr compared to the pre-injection baseline. Thus, the present results are consistent with the hypothesis that GABAergic tone in SNr plays a role in the regulation of tremulous jaw movements. This research may lead to a better understanding of how parkinsonian symptoms are modulated by SNr GABA mechanisms.

Sequential enzymatic derivatization coupled with online microdialysis sampling for simultaneous profiling of mouse tumor extracellular hydrogen peroxide, lactate, and glucose.

PubMed

Su, Cheng-Kuan; Tseng, Po-Jen; Chiu, Hsien-Ting; Del Vall, Andrea; Huang, Yu-Fen; Sun, Yuh-Chang

2017-03-01

Probing tumor extracellular metabolites is a vitally important issue in current cancer biology. In this study an analytical system was constructed for the in vivo monitoring of mouse tumor extracellular hydrogen peroxide (H 2 O 2 ), lactate, and glucose by means of microdialysis (MD) sampling and fluorescence determination in conjunction with a smart sequential enzymatic derivatization scheme-involving a loading sequence of fluorogenic reagent/horseradish peroxidase, microdialysate, lactate oxidase, pyruvate, and glucose oxidase-for step-by-step determination of sampled H 2 O 2 , lactate, and glucose in mouse tumor microdialysate. After optimization of the overall experimental parameters, the system's detection limit reached as low as 0.002 mM for H 2 O 2 , 0.058 mM for lactate, and 0.055 mM for glucose, based on 3 μL of microdialysate, suggesting great potential for determining tumor extracellular concentrations of lactate and glucose. Spike analyses of offline-collected mouse tumor microdialysate and monitoring of the basal concentrations of mouse tumor extracellular H 2 O 2 , lactate, and glucose, as well as those after imparting metabolic disturbance through intra-tumor administration of a glucose solution through a prior-implanted cannula, were conducted to demonstrate the system's applicability. Our results evidently indicate that hyphenation of an MD sampling device with an optimized sequential enzymatic derivatization scheme and a fluorescence spectrometer can be used successfully for multi-analyte monitoring of tumor extracellular metabolites in living animals. Copyright © 2016 Elsevier B.V. All rights reserved.

Malignant infarction of the middle cerebral artery in a porcine model. A pilot study

PubMed Central

Martínez-Valverde, Tamara; Sánchez-Guerrero, Ángela; Campos, Mireia; Esteves, Marielle; Gandara, Dario; Torné, Ramon; Castro, Lidia; Dalmau, Antoni; Tibau, Joan

2017-01-01

Background and purpose Interspecies variability and poor clinical translation from rodent studies indicate that large gyrencephalic animal stroke models are urgently needed. We present a proof-of-principle study describing an alternative animal model of malignant infarction of the middle cerebral artery (MCA) in the common pig and illustrate some of its potential applications. We report on metabolic patterns, ionic profile, brain partial pressure of oxygen (PtiO2), expression of sulfonylurea receptor 1 (SUR1), and the transient receptor potential melastatin 4 (TRPM4). Methods A 5-hour ischemic infarct of the MCA territory was performed in 5 2.5-to-3-month-old female hybrid pigs (Large White x Landrace) using a frontotemporal approach. The core and penumbra areas were intraoperatively monitored to determine the metabolic and ionic profiles. To determine the infarct volume, 2,3,5-triphenyltetrazolium chloride staining and immunohistochemistry analysis was performed to determine SUR1 and TRPM4 expression. Results PtiO2 monitoring showed an abrupt reduction in values close to 0 mmHg after MCA occlusion in the core area. Hourly cerebral microdialysis showed that the infarcted tissue was characterized by reduced concentrations of glucose (0.03 mM) and pyruvate (0.003 mM) and increases in lactate levels (8.87mM), lactate-pyruvate ratio (4202), glycerol levels (588 μM), and potassium concentration (27.9 mmol/L). Immunohistochemical analysis showed increased expression of SUR1-TRPM4 channels. Conclusions The aim of the present proof-of-principle study was to document the feasibility of a large animal model of malignant MCA infarction by performing transcranial occlusion of the MCA in the common pig, as an alternative to lisencephalic animals. This model may be useful for detailed studies of cerebral ischemia mechanisms and the development of neuroprotective strategies. PMID:28235044

Hyperbaric oxygen therapy may overcome nitric oxide blockage during cyanide intoxication.

PubMed

Polzik, Peter; Hansen, Marco Bo; Olsen, Niels Vidiendal; Grøndal, Olav; Hyldegaard, Ole

2017-01-01

To determine the effects of a blockade of nitric oxide (NO) synthesis on hyperbaric oxygen (HBO₂) therapy during cyanide (CN) intoxication. 39 anesthetized female Sprague-Dawley rats were exposed to CN intoxication (5.4 mg/kg intra-arterially) with or without previous nitric oxide synthase (NOS) inhibition by L-NG-nitroarginine methyl ester (L-NAME) injection (40 mg/kg intraperitoneally). Subsequently, either HBO₂ therapy (284 kPa/90 minutes), normobaric oxygen therapy (100% oxygen/90 minutes) or nothing was administered. Intracerebral microdialysis was used to measure the interstitial brain concentration of lactate, glucose, glycerol and lactate/pyruvate ratios. L-NAME potentiated CN intoxication by higher maximum and prolonged lactate (in mM: 0. 5 ± 0.3 vs. 0.7 ± 0.4, P ⟨ 0.005) concentrations compared with solely CN-intoxicated rats. The same trend was found for mean glucose, glycerol and lactate/pyruvate ratio levels. During HBO₂ treatment a sustained reduction occurred in mean lactate levels (in mM: 0.5 ± 0.5 vs. 0.7 ± 0.4, P ⟨ 0.01) regardless of NOS blockade by L-NAME. The same trend was found for mean glucose and glycerol levels. The results suggest that blocking NOS using L-NAME can worsen acute CN intoxication. HBO₂ treatment can partially overcome this block and continue to ameliorate CN intoxication.

Transcranial direct-current stimulation increases extracellular dopamine levels in the rat striatum

PubMed Central

Tanaka, Tomoko; Takano, Yuji; Tanaka, Satoshi; Hironaka, Naoyuki; Kobayashi, Kazuto; Hanakawa, Takashi; Watanabe, Katsumi; Honda, Manabu

2013-01-01

Background: Transcranial direct-current stimulation (tDCS) is a non-invasive procedure that achieves polarity-dependent modulation of neuronal membrane potentials. It has recently been used as a functional intervention technique for the treatment of psychiatric and neurological diseases; however, its neuronal mechanisms have not been fully investigated in vivo. Objective/Hypothesis: To investigate whether the application of cathodal or anodal tDCS affects extracellular dopamine and serotonin levels in the rat striatum. Methods: Stimulation and in vivo microdialysis were carried out under urethane anesthesia, and microdialysis probes were slowly inserted into the striatum. After the collection of baseline fractions in the rat striatum, cathodal or anodal tDCS was applied continuously for 10 min with a current intensity of 800 μA from an electrode placed on the skin of the scalp. Dialysis samples were collected every 10 min until at least 400 min after the onset of stimulation. Results: Following the application of cathodal, but not anodal, tDCS for 10 min, extracellular dopamine levels increased for more than 400 min in the striatum. There were no significant changes in extracellular serotonin levels. Conclusion: These findings suggest that tDCS has a direct and/or indirect effect on the dopaminergic system in the rat basal ganglia. PMID:23596399

Paramecium caudatum as a source of nitric oxide: Chemiluminescent detection based on Bluestar® Forensic reagent connected with microdialysis.

PubMed

Bancirova, Martina

2017-11-01

Nitric oxide (NO) chemistry inside the body is the most interesting part of its behavior. NO is involved in controlling blood pressure, and in transmitting nerve signals and a variety of other signaling processes. To explain the behavior of NO, it is necessary to determine its immediate concentration or observe time-dependent changes in its concentration. In Paramecium caudatum, NO is formed by calcium-dependent nNOS (NOS1)-like protein, which is distributed in the cytoplasm. NO synthesis affects the ciliary beat and consequent motility of cells and blocked NO synthesis reduces the ability of cells to move. The possibility of online coupling of microdialysis (of P. caudatum solution) with NO detection is demonstrated. Direct measurement of NO is carried out using dilute Bluestar ® Forensic reagent (luminol-H 2 O 2 system; one of the NO detections is based upon the chemiluminescent reaction between NO and the luminol-H 2 O 2 system, which is specifically reactive to NO). The effect of a nitric oxide synthase inhibitor, NG-nitro-l-arginine methyl ester was observed. NO production was inhibited and the movement of P. caudatum was restricted. These effects were time dependent and after a specific time were reversed. Copyright © 2017 John Wiley & Sons, Ltd.

Minimally invasive monitoring of skeletal muscle hypermetabolism induced by the phosphodiesterase-III-inhibitor milrinone and sodium fluoride.

PubMed

Schuster, Frank; Johannsen, Stephan; Roewer, Norbert; Anetseder, Martin

2013-04-01

We hypothesized that the phosphodiesterase-III-inhibitor milrinone and the non-specific G-protein activator sodium fluoride increase the skeletal muscular lactate levels as a sign of a hypermetabolic response. With approval of the local animal care committee Sprague-Dawley rats were killed and artificially perfused either with Ringer's solution or sodium fluoride 110 mM, while milrinone 1.32 mM or Ringer's solution at 1 μl/min was applied via microdialysis probes in both hind limbs. Lactate was measured spectrophotometrically in the dialysate. Baseline lactate levels before drug application did not differ between hind limbs. Local infusion of milrinone via microdialysis did not significantly increase intramuscular lactate concentrations compared with the Ringer control group. Muscular perfusion with sodium fluoride resulted in a significant increase of lactate and was potentiated by combination with local milrinone. Phosphodiesterase-III-inhibition alone does not significantly influence the lactate levels in skeletal muscle of sacrificed rats. Sodium fluoride infusion leads to an intramuscular lactate increase, which was further potentiated by local inhibition of phosphodiesterase-III. The fluoride-mediated hypermetabolic response following sodium fluoride could be a possible explanation for the observed myotoxic adverse effects in individuals treated by fluoride-containing agents. © 2012 The Authors. JPP © 2012. Royal Pharmaceutical Society.

Efficacious Cefazolin Prophylactic Dose for Morbidly Obese Women Undergoing Bariatric Surgery Based on Evidence from Subcutaneous Microdialysis and Populational Pharmacokinetic Modeling.

PubMed

Palma, Eduardo Celia; Meinhardt, Nelson Guardiola; Stein, Airton Tetelbom; Heineck, Isabela; Fischer, Maria Isabel; de Araújo, BibianaVerlindo; Dalla Costa, Teresa

2018-04-11

To determine the efficacious cefazolin prophylactic dose for bariatric surgery using free subcutaneous concentrations accessed by microdialysis after 2 g or 3 g i.v. bolus dosing to morbidly obese women and POPPK modeling. A POPPK model with variable plasma and subcutaneous tissue protein binding was developed to simultaneously describe plasma and tissue data sets. The outcomes was predicted for common surgical site infection (SSI) bacteria over 3, 4, 5 and 6 h periods postdose, as probability of target attainment (PTA) using Monte Carlo simulation. CFZ 2 g warrant up to 5 h SSI prophylaxis for bacteria with MICs ≤1 mg/L such as Escherichia coli and Staphylococcus aureus. For species such as Klebsiella pneumoniae, which present MIC distribution frequency of 2 mg/L, the maintenance of PTA ≥ 90% occurs with a 3 g dose for surgeries lasting up to 5 h, and 2 g dose provide an adequate response up to 4 h (PTA of 89%). Effectiveness of CFZ 2 g is similar to 3 g against bacteria with a MIC up to 2 mg/L, especially if the surgery does not last for more than 4 h.

Ocular silicon distribution and clearance following intravitreal injection of porous silicon microparticles

PubMed Central

Nieto, Alejandra; Hou, Huiyuan; Sailor, Michael J.; Freeman, William R.; Cheng, Lingyun

2013-01-01

Porous silicon (pSi) microparticles have been investigated for intravitreal drug delivery and demonstrated good biocompatibility. With the appropriate surface chemistry, pSi can reside in vitreous for months or longer. However, ocular distribution and clearance pathway of its degradation product, silicic acid, are not well understood. In the current study, rabbit ocular tissue was collected at different time point following fresh pSi (day 1, 5, 9, 16, and 21) or oxidized pSi (day 3, 7, 14, 21, and 35) intravitreal injection. In addition, dual-probe simultaneous microdialysis of aqueous and vitreous humor was performed following a bolus intravitreal injection of 0.25 mL silicic acid (150 μg/mL) and six consecutive microdialysates were collected every 20 min. Silicon was quantified from the samples using inductively coupled plasma-optical emission spectroscopy. The study showed that following the intravitreal injection of oxidized pSi, free silicon was consistently higher in the aqueous than in the retina (8.1 ± 6.5 vs. 3.4 ± 3.9 μg/mL, p = 0.0031). The area under the concentration-time curve (AUC) of the retina was only about 24% that of the aqueous. The mean residence time was 16 days for aqueous, 13 days for vitreous, 6 days for retina, and 18 days for plasma. Similarly, following intravitreal fresh pSi, free silicon was also found higher in aqueous than in retina (7 ± 4.7 vs. 3.4 ± 4.1 μg/mL, p = 0.014). The AUC for the retina was about 50% of the AUC for the aqueous. The microdialysis revealed the terminal half-life of free silicon in the aqueous was 30 min and 92 min in the vitreous; the AUC for aqueous accounted for 38% of the AUC for vitreous. Our studies indicate that aqueous humor is a significant pathway for silicon egress from the eye following intravitreal injection of pSi crystals. PMID:24036388

Enhancement of cortical extracellular 5-HT by 5-HT1A and 5-HT2C receptor blockade restores the antidepressant-like effect of citalopram in non-responder mice.

PubMed

Calcagno, Eleonora; Guzzetti, Sara; Canetta, Alessandro; Fracasso, Claudia; Caccia, Silvio; Cervo, Luigi; Invernizzi, Roberto W

2009-07-01

We recently found that the response of DBA/2 mice to SSRIs in the forced swim test (FST) was impaired and they also had a smaller basal and citalopram-stimulated increase in brain extracellular serotonin (5-HT) than 'responder' strains. We employed intracerebral microdialysis, FST and selective antagonists of 5-HT1A and 5-HT2C receptors to investigate whether enhancing the increase in extracellular 5-HT reinstated the anti-immobility effect of citalopram in the FST. WAY 100635 (0.3 mg/kg s.c.) or SB 242084 (1 mg/kg s.c.), respectively a selective 5-HT1A and 5-HT2C receptor antagonist, raised the effect of citalopram (5 mg/kg) on extracellular 5-HT in the medial prefrontal cortex of DBA/2N mice (citalopram alone 5.2+/-0.3 fmol/20 microl, WAY 100635+citalopram 9.9+/-2.1 fmol/20 microl, SB 242084+ citalopram 7.6+/-1.0 fmol/20 microl) to the level reached in 'responder' mice given citalopram alone. The 5-HT receptor antagonists had no effect on the citalopram-induced increase in extracellular 5-HT in the dorsal hippocampus. The combination of citalopram with WAY 100635 or SB 242084 significantly reduced immobility time in DBA/2N mice that otherwise did not respond to either drug singly. Brain levels of citalopram in mice given citalopram alone or with 5-HT antagonists did not significantly differ. The results confirm that impaired 5-HT transmission accounts for the lack of effect of citalopram in the FST and suggest that enhancing the effect of SSRIs on extracellular 5-HT, through selective blockade of 5-HT1A and 5-HT2C receptors, could be a useful strategy to restore the response in treatment-resistant depression.

Role of the Suprachiasmatic and Arcuate Nuclei in Diurnal Temperature Regulation in the Rat.

PubMed

Guzmán-Ruiz, Mara Alaide; Ramirez-Corona, Arlen; Guerrero-Vargas, Natali Nadia; Sabath, Elizabeth; Ramirez-Plascencia, Oscar Daniel; Fuentes-Romero, Rebecca; León-Mercado, Luis Abel; Basualdo Sigales, MariCarmen; Escobar, Carolina; Buijs, Ruud Marinus

2015-11-18

In mammals, daily changes in body temperature (Tb) depend on the integrity of the suprachiasmatic nucleus (SCN). Fasting influences the Tb in the resting period and the presence of the SCN is essential for this process. However, the origin of this circadian/metabolic influence is unknown. We hypothesized that, not only the SCN but also the arcuate nucleus (ARC), are involved in the Tb setting through afferents to the thermoregulatory median preoptic nucleus (MnPO). Therefore, we investigated by neuronal tracing and microdialysis experiments the possible targeting of the MnPO by the SCN and the ARC in male Wistar rats. We observed that vasopressin release from the SCN decreases the temperature just before light onset, whereas α-melanocyte stimulating hormone release, especially at the end of the dark period, maintains high temperature. Both peptides have opposite effects on the brown adipose tissue activity through thermoregulatory nuclei such as the dorsomedial nucleus of the hypothalamus and the dorsal raphe nucleus. The present study indicates that the coordination between circadian and metabolic signaling within the hypothalamus is essential for an adequate temperature control. When circadian and metabolic systems are not well synchronized, individuals may develop metabolic diseases. The underlying mechanisms are unknown. Here, we demonstrate that the balance between the releases of neuropeptides derived from the biological clock and from a metabolic sensory organ as the arcuate nucleus, are essential for an adequate temperature control. These observations show that brain areas involved in circadian and metabolic functions of the body need to interact to produce a coherent arrangement of physiological processes associated with temperature control. Copyright © 2015 the authors 0270-6474/15/3515419-11$15.00/0.

Oral methylphenidate alleviates the fine motor dysfunction caused by chronic postnatal manganese exposure in adult rats.

PubMed

Beaudin, Stéphane A; Strupp, Barbara J; Lasley, Stephen M; Fornal, Casimir A; Mandal, Shyamali; Smith, Donald R

2015-04-01

Developmental manganese (Mn) exposure is associated with motor dysfunction in children and animal models, but little is known about the underlying neurochemical mechanisms or the potential for amelioration by pharmacotherapy. We investigated whether methylphenidate (MPH) alleviates fine motor dysfunction due to chronic postnatal Mn exposure, and whether Mn exposure impairs brain extracellular dopamine (DA) and norepinephrine (NE) in the prefrontal cortex (PFC) and striatum in adult animals. Rats were orally exposed to 0 or 50 mg Mn/kg/day from postnatal day 1 until the end of the study (PND 145). The staircase test was used to assess skilled forelimb function. Oral MPH (2.5 mg/kg/day) was administered daily 1 h before staircase testing for 16 days. DA and NE levels were measured by dual probe microdialysis. Results show that Mn exposure impaired reaching and grasping skills and the evoked release of DA and NE in the PFC and striatum of adult rats. Importantly, oral MPH treatment fully alleviated the fine motor deficits in the Mn-exposed animals, but did not affect forelimb skills of control rats not exposed to Mn. These results suggest that catecholaminergic hypofunctioning in the PFC and striatum may underlie the Mn-induced fine motor dysfunction, and that oral MPH pharmacotherapy is an effective treatment approach for alleviating this dysfunction in adult animals. The therapeutic potential of MPH for the treatment of motor dysfunction in Mn-exposed children and adults appears promising pending further characterization of MPH efficacy in other functional areas (eg, attention) believed to be affected by developmental Mn exposure. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Effect of novel atypical antipsychotic, blonanserin, on extracellular neurotransmitter level in rat prefrontal cortex.

PubMed

Ohoyama, Keiko; Yamamura, Satoshi; Hamaguchi, Tatsuya; Nakagawa, Masanori; Motomura, Eishi; Shiroyama, Takashi; Tanii, Hisashi; Okada, Motohiro

2011-02-25

To clarify the mechanisms of action of blonanserin, an atypical antipsychotic drug, we studied the effects of systemic administration of blonanserin and risperidone on extracellular levels of norepinephrine, dopamine, serotonin, GABA and glutamate in the medial prefrontal cortex using microdialysis, and neuronal firing in the ventral tegmental area, locus coeruleus, dorsal raphe nucleus and mediodorsal thalamic nucleus using radiotelemetry. The binding affinities of blonanserin to D(2) and 5-HT(2A) receptors in the rat brain were confirmed and found to be similar. Blonanserin transiently increased neuronal firing in locus coeruleus and ventral tegmental area but not in dorsal raphe nucleus or mediodorsal thalamic nucleus, whereas risperidone increased the firing in locus coeruleus, ventral tegmental area and dorsal raphe nucleus but not in mediodorsal thalamic nucleus. Blonanserin persistently increased frontal extracellular levels of norepinephrine and dopamine but not serotonin, GABA or glutamate, whereas risperidone persistently increased those of norepinephrine, dopamine and serotonin but not GABA or glutamate. These results suggest a pharmacological correlation between the stimulatory effects of these antipsychotics on frontal monoamine release and neuronal activity in monoaminergic nuclei. Inhibition of the α(2) adrenoceptor increased extracellular monoamine levels and enhanced blonanserin-induced increase in extracellular serotonin level. These results indicated that the combination of antagonism of D(2) and 5-HT(2A) receptors contribute to the rise in extracellular levels of norepinephrine and dopamine, and that α(2) adrenoceptors play important roles in frontal serotonin release. They also suggest that blonanserin-induced activation of monoaminergic transmission could be, at least partially, involved in atypical antipsychotic properties of blonanserin. Copyright © 2010 Elsevier B.V. All rights reserved.

Mu Opioid Receptors in Gamma-Aminobutyric Acidergic Forebrain Neurons Moderate Motivation for Heroin and Palatable Food.

PubMed

Charbogne, Pauline; Gardon, Olivier; Martín-García, Elena; Keyworth, Helen L; Matsui, Aya; Mechling, Anna E; Bienert, Thomas; Nasseef, Taufiq; Robé, Anne; Moquin, Luc; Darcq, Emmanuel; Ben Hamida, Sami; Robledo, Patricia; Matifas, Audrey; Befort, Katia; Gavériaux-Ruff, Claire; Harsan, Laura-Adela; von Elverfeldt, Dominik; Hennig, Jurgen; Gratton, Alain; Kitchen, Ian; Bailey, Alexis; Alvarez, Veronica A; Maldonado, Rafael; Kieffer, Brigitte L

2017-05-01

Mu opioid receptors (MORs) are central to pain control, drug reward, and addictive behaviors, but underlying circuit mechanisms have been poorly explored by genetic approaches. Here we investigate the contribution of MORs expressed in gamma-aminobutyric acidergic forebrain neurons to major biological effects of opiates, and also challenge the canonical disinhibition model of opiate reward. We used Dlx5/6-mediated recombination to create conditional Oprm1 mice in gamma-aminobutyric acidergic forebrain neurons. We characterized the genetic deletion by histology, electrophysiology, and microdialysis; probed neuronal activation by c-Fos immunohistochemistry and resting-state functional magnetic resonance imaging; and investigated main behavioral responses to opiates, including motivation to obtain heroin and palatable food. Mutant mice showed MOR transcript deletion mainly in the striatum. In the ventral tegmental area, local MOR activity was intact, and reduced activity was only observed at the level of striatonigral afferents. Heroin-induced neuronal activation was modified at both sites, and whole-brain functional networks were altered in live animals. Morphine analgesia was not altered, and neither was physical dependence to chronic morphine. In contrast, locomotor effects of heroin were abolished, and heroin-induced catalepsy was increased. Place preference to heroin was not modified, but remarkably, motivation to obtain heroin and palatable food was enhanced in operant self-administration procedures. Our study reveals dissociable MOR functions across mesocorticolimbic networks. Thus, beyond a well-established role in reward processing, operating at the level of local ventral tegmental area neurons, MORs also moderate motivation for appetitive stimuli within forebrain circuits that drive motivated behaviors. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Mechanisms of Kappa Opioid Receptor Potentiation of Dopamine D2 Receptor Function in Quinpirole-Induced Locomotor Sensitization in Rats.

PubMed

Escobar, Angélica P; González, Marcela P; Meza, Rodrigo C; Noches, Verónica; Henny, Pablo; Gysling, Katia; España, Rodrigo A; Fuentealba, José A; Andrés, María E

2017-08-01

Increased locomotor activity in response to the same stimulus is an index of behavioral sensitization observed in preclinical models of drug addiction and compulsive behaviors. Repeated administration of quinpirole, a D2/D3 dopamine agonist, induces locomotor sensitization. This effect is potentiated and accelerated by co-administration of U69593, a kappa opioid receptor agonist. The mechanism underlying kappa opioid receptor potentiation of quinpirole-induced locomotor sensitization remains to be elucidated. Immunofluorescence anatomical studies were undertaken in mice brain slices and rat presynaptic synaptosomes to reveal kappa opioid receptor and D2R pre- and postsynaptic colocalization in the nucleus accumbens. Tonic and phasic dopamine release in the nucleus accumbens of rats repeatedly treated with U69593 and quinpirole was assessed by microdialysis and fast scan cyclic voltammetry. Anatomical data show that kappa opioid receptor and D2R colocalize postsynaptically in medium spiny neurons of the nucleus accumbens and the highest presynaptic colocalization occurs on the same dopamine terminals. Significantly reduced dopamine levels were observed in quinpirole, and U69593-quinpirole treated rats, explaining sensitization of D2R. Presynaptic inhibition induced by kappa opioid receptor and D2R of electrically evoked dopamine release was faster in U69593-quinpirole compared with quinpirole-repeatedly treated rats. Pre- and postsynaptic colocalization of kappa opioid receptor and D2R supports a role for kappa opioid receptor potentiating both the D2R inhibitory autoreceptor function and the inhibitory action of D2R on efferent medium spiny neurons. Kappa opioid receptor co-activation accelerates D2R sensitization by contributing to decrease dopamine release in the nucleus accumbens. © The Author 2017. Published by Oxford University Press on behalf of CINP.

Reduced dopamine and glutamate neurotransmission in the nucleus accumbens of quinpirole-sensitized rats hints at inhibitory D2 autoreceptor function.

PubMed

Escobar, Angélica P; Cornejo, Francisca A; Olivares-Costa, Montserrat; González, Marcela; Fuentealba, José A; Gysling, Katia; España, Rodrigo A; Andrés, María E

2015-09-01

Dopamine from the ventral tegmental area and glutamate from several brain nuclei converge in the nucleus accumbens (NAc) to drive motivated behaviors. Repeated activation of D2 receptors with quinpirole (QNP) induces locomotor sensitization and compulsive behaviors, but the mechanisms are unknown. In this study, in vivo microdialysis and fast scan cyclic voltammetry in adult anesthetized rats were used to investigate the effect of repeated QNP on dopamine and glutamate neurotransmission within the NAc. Following eight injections of QNP, a significant decrease in phasic and tonic dopamine release was observed in rats that displayed locomotor sensitization. Either a systemic injection or the infusion of QNP into the NAc decreased dopamine release, and the extent of this effect was similar in QNP-sensitized and control rats, indicating that inhibitory D2 autoreceptor function is maintained despite repeated activation of D2 receptors and decreased dopamine extracellular levels. Basal extracellular levels of glutamate in the NAc were also significantly lower in QNP-treated rats than in controls. Moreover, the increase in NAc glutamate release induced by direct stimulation of medial prefrontal cortex was significantly lower in QNP-sensitized rats. Together, these results indicate that repeated activation of D2 receptors disconnects NAc from medial prefrontal cortex and ventral tegmental area. Repeated administration of the dopamine D2 receptor agonist quinpirole (QNP) induces locomotor sensitization. We found that the NAc of QNP-sensitized rats has reduced glutamate levels coming from prefrontal cortex together with a decreased phasic and tonic dopamine neurotransmission but a conserved presynaptic D2 receptor function. We suggest that locomotor sensitization is because of increased affinity state of D2 post-synaptic receptors. © 2015 International Society for Neurochemistry.

Nucleus accumbens hyperpolarization-activated cyclic nucleotide-gated channels modulate methamphetamine self-administration in rats.

PubMed

Cao, Dan-Ni; Song, Rui; Zhang, Shu-Zhuo; Wu, Ning; Li, Jin

2016-08-01

Methamphetamine addiction is believed to primarily result from increased dopamine release and the inhibition of dopamine uptake. Some evidence suggests that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play important roles in the functional modulation of dopaminergic neurons and the pathophysiology of related diseases. However, little is known about the effects of HCN channels on methamphetamine addiction. The present study investigated the role of brain HCN channels in methamphetamine addiction. Acute intracerebroventricular (i.c.v.) injection or bilateral intra-accumbens microinjections of non-selective HCN channel blocker ZD7288 (0.3125 and 0.625 μg) significantly reduced both methamphetamine (0.0125 or 0.05 mg/kg/infusion)-induced self-administration under fixed ratio 2 reinforcement and the breakpoint of methamphetamine (0.05 mg/kg/infusion) under progressive ratio reinforcement in rats. Moreover, compared with i.c.v. injection, bilateral intra-accumbens microinjections of ZD7288 exerted stronger inhibitory effects, suggesting that blockade of HCN channels in the nucleus accumbens reduced the reinforcing effects of and motivation for methamphetamine. We also found that ZD7288 (0.625 and 1.25 μg, i.c.v.) significantly decreased methamphetamine (1 mg/kg, intraperitoneal (i.p.))-induced hyperactivity with no effect on the spontaneous activity in rats. Finally, in vivo microdialysis experiments showed that the HCN channel blockade using ZD7288 (0.625 and 1.25 μg, i.c.v.) decreased methamphetamine (1 mg/kg, i.p.)-induced elevation of extracellular dopamine levels in the nucleus accumbens. These results indicate that HCN channels in the nucleus accumbens are involved in the reinforcing properties of methamphetamine and highlight the importance of HCN channels in the regulation of dopamine neurotransmission underlying methamphetamine addiction.

Pharmacology of basimglurant (RO4917523, RG7090), a unique metabotropic glutamate receptor 5 negative allosteric modulator in clinical development for depression.

PubMed

Lindemann, Lothar; Porter, Richard H; Scharf, Sebastian H; Kuennecke, Basil; Bruns, Andreas; von Kienlin, Markus; Harrison, Anthony C; Paehler, Axel; Funk, Christoph; Gloge, Andreas; Schneider, Manfred; Parrott, Neil J; Polonchuk, Liudmila; Niederhauser, Urs; Morairty, Stephen R; Kilduff, Thomas S; Vieira, Eric; Kolczewski, Sabine; Wichmann, Juergen; Hartung, Thomas; Honer, Michael; Borroni, Edilio; Moreau, Jean-Luc; Prinssen, Eric; Spooren, Will; Wettstein, Joseph G; Jaeschke, Georg

2015-04-01

Major depressive disorder (MDD) is a serious public health burden and a leading cause of disability. Its pharmacotherapy is currently limited to modulators of monoamine neurotransmitters and second-generation antipsychotics. Recently, glutamatergic approaches for the treatment of MDD have increasingly received attention, and preclinical research suggests that metabotropic glutamate receptor 5 (mGlu5) inhibitors have antidepressant-like properties. Basimglurant (2-chloro-4-[1-(4-fluoro-phenyl)-2,5-dimethyl-1H-imidazol-4-ylethynyl]-pyridine) is a novel mGlu5 negative allosteric modulator currently in phase 2 clinical development for MDD and fragile X syndrome. Here, the comprehensive preclinical pharmacological profile of basimglurant is presented with a focus on its therapeutic potential for MDD and drug-like properties. Basimglurant is a potent, selective, and safe mGlu5 inhibitor with good oral bioavailability and long half-life supportive of once-daily administration, good brain penetration, and high in vivo potency. It has antidepressant properties that are corroborated by its functional magnetic imaging profile as well as anxiolytic-like and antinociceptive features. In electroencephalography recordings, basimglurant shows wake-promoting effects followed by increased delta power during subsequent non-rapid eye movement sleep. In microdialysis studies, basimglurant had no effect on monoamine transmitter levels in the frontal cortex or nucleus accumbens except for a moderate increase of accumbal dopamine, which is in line with its lack of pharmacological activity on monoamine reuptake transporters. These data taken together, basimglurant has favorable drug-like properties, a differentiated molecular mechanism of action, and antidepressant-like features that suggest the possibility of also addressing important comorbidities of MDD including anxiety and pain as well as daytime sleepiness and apathy or lethargy. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Mephedrone, compared with MDMA (ecstasy) and amphetamine, rapidly increases both dopamine and 5-HT levels in nucleus accumbens of awake rats

PubMed Central

Kehr, J; Ichinose, F; Yoshitake, S; Goiny, M; Sievertsson, T; Nyberg, F; Yoshitake, T

2011-01-01

BACKGROUND AND PURPOSE The designer drug 1-(4-methylphenyl)-2-methylaminopropan-1-one (4-methylmethcathinone, mephedrone) is reported to possess psychostimulant, entactogenic and hallucinogenic effects. The purpose of this study was to examine the effects of acute administration of mephedrone on extracellular levels of dopamine (DA) and 5-HT in the nucleus accumbens of awake rats and compare these effects with those induced by 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and amphetamine. EXPERIMENTAL APPROACH Microdialysis sampling was performed while simultaneously recording locomotor activity in rats and the monoamines were determined by HPLC with electrochemical detection. KEY RESULTS Mephedrone (3 mg·kg−1 s.c.) and (+)-amphetamine (1 mg·kg−1 s.c.) caused rapid increases in extracellular DA levels of 496% and 412%, respectively, whereas MDMA (3 mg·kg−1 s.c.) showed only a moderate effect (235%). The corresponding 5-HT levels increased to 941% (mephedrone) and 911% (MDMA), but only to 165% following amphetamine. The calculated t1/2 values for elimination rate of mephedrone, MDMA and amphetamine-induced increases in extracellular DA levels were 25, 303 and 51 min, the corresponding t1/2 values for 5-HT were 26, 48 and 84 min, respectively. Locomotor activity was increased most by amphetamine, whereas both mephedrone and MDMA showed about three times lower and shorter-lasting effects. CONCLUSIONS AND IMPLICATIONS The neurochemical and functional properties of mephedrone resemble those of MDMA, but it also shows an amphetamine-like effect in that it evokes a rapid release and elimination of DA in the brain reward system, a feature that may contribute to its potent re-inforcing properties. PMID:21615721

In vivo evaluation of the hippocampal glutamate, GABA and the BDNF levels associated with spatial memory performance in a rodent model of neuropathic pain.

PubMed

Saffarpour, S; Shaabani, M; Naghdi, N; Farahmandfar, M; Janzadeh, A; Nasirinezhad, F

2017-06-01

Patients with chronic pain usually suffer from learning and memory impairment which may significantly decrease their quality of life. Despite laboratory and clinical studies, the mechanism underlying this memory impairment remains elusive. We evaluated the effect of chronic pain on the glutamate and GABA levels and BDNF expression in the CA1 region of hippocampus as a possible explanation for memory impairment related to neuropathic pain. In this respect, 30 male rats were randomly allocated to 3 groups as control, sham and neuropathic. Neuropathic pain was induced by a chronic constriction injury of the sciatic nerve (CCI) and mechanical allodynia and the spatial memory was assessed using the Von Frey filaments and Morris water maze respectively. To determine the potential mechanisms, the in vivo extracellular levels of glutamate and γ-aminobutyric acid (GABA) were measured by microdialysis and the brain-derived neurotrophic factor (BDNF) expression was determined by using western blots technique in the hippocampus on days 14 and 21 post-CCI. We showed that CCI impaired spatial learning and memory in Morris water maze (MWM) task. BDNF expression level and glutamate concentration significantly decreased in rats with chronic constriction injury of the sciatic nerve (P<0.001, F=7.3, F=23.23). In addition, GABA increased in hippocampal CA1 region (P<0.001, F=39.2) when the pain threshold was minimum. Nevertheless, these changes reversed while pain was relieved spontaneously. Chronic pain induced by constriction of the sciatic nerve impairs the spatial learning and memory function in rats. This effect exerts through the increase in GABA concentration and decrease in the glutamate and BDNF levels in the CA1 region of the hippocampus. Copyright © 2017 Elsevier Inc. All rights reserved.

GEBR-7b, a novel PDE4D selective inhibitor that improves memory in rodents at non-emetic doses.

PubMed

Bruno, O; Fedele, E; Prickaerts, J; Parker, L A; Canepa, E; Brullo, C; Cavallero, A; Gardella, E; Balbi, A; Domenicotti, C; Bollen, E; Gijselaers, H J M; Vanmierlo, T; Erb, K; Limebeer, C L; Argellati, F; Marinari, U M; Pronzato, M A; Ricciarelli, R

2011-12-01

Strategies designed to enhance cerebral cAMP have been proposed as symptomatic treatments to counteract cognitive deficits. However, pharmacological therapies aimed at reducing PDE4, the main class of cAMP catabolizing enzymes in the brain, produce severe emetic side effects. We have recently synthesized a 3-cyclopentyloxy-4-methoxybenzaldehyde derivative, structurally related to rolipram, and endowed with selective PDE4D inhibitory activity. The aim of the present study was to investigate the effect of the new drug, namely GEBR-7b, on memory performance, nausea, hippocampal cAMP and amyloid-β (Aβ) levels. To measure memory performance, we performed object recognition tests on rats and mice treated with GEBR-7b or rolipram. The emetic potential of the drug, again compared with rolipram, was evaluated in rats using the taste reactivity test and in mice using the xylazine/ketamine anaesthesia test. Extracellular hippocampal cAMP was evaluated by intracerebral microdialysis in freely moving rats. Levels of soluble Aβ peptides were measured in hippocampal tissues and cultured N2a cells by elisa. GEBR-7b increased hippocampal cAMP, did not influence Aβ levels and improved spatial, as well as object memory performance in the object recognition tests. The effect of GEBR-7b on memory was 3 to 10 times more potent than that of rolipram, and its effective doses had no effect on surrogate measures of emesis in rodents. Our results demonstrate that GEBR-7b enhances memory functions at doses that do not cause emesis-like behaviour in rodents, thus offering a promising pharmacological perspective for the treatment of memory impairment. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Protection from inorganic mercury effects on the in vivo dopamine release by ionotropic glutamate receptor antagonists and nitric oxide synthase inhibitors.

PubMed

Vidal, Lucía; Durán, Rafael; Faro, Lilian F; Campos, Francisco; Cervantes, Rosa C; Alfonso, Miguel

2007-09-05

The possible role of ionotropics glutamate receptors on the HgCl(2)-induced dopamine (DA) release from rat striatum was investigated by using in vivo brain microdialysis technique after administration of selective NMDA and AMPA/Kainate receptors antagonists dizocilpine (MK-801), D (-)-2-amino-5-phoshonopentanoic acid (AP5), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Moreover, we have also studied the effects of nitric oxide synthase (NOS) inhibitors L-nitro-arginine methyl ester (L-NAME) and 7-nitro-indazol (7-NI) on HgCl(2)-induced DA release. Intraestriatal infusion of 1mM HgCl(2) increased striatal DA to 1717.2+/-375.4% respect to basal levels. Infusion of 1mM HgCl(2) in 400 microM MK-801 pre-treated animals produced an increase on striatal DA levels 61% smaller than that induced in non-pre-treated animals. In the case of AP5, this treatment reduced 92% the increase produced by HgCl(2) as compared to non-pre-treated rats. Nevertheless, the administration of CNQX did not produce any effect on HgCl(2)-induced dopamine release. Intrastriatal infusion of 1mM HgCl(2) in 100 microM L-NAME pre-treated animals produced an increase on extracellular DA levels 82% smaller than produced by HgCl(2) alone. In addition, the pre-treatment with 7-NI reduced 90% the increase produced by infusion of HgCl(2) alone in rats. Thus, HgCl(2)-induced DA release could be produced at last in part, by overstimulation of NMDA receptors with NO production, since administration of NMDA receptor antagonists and NOS inhibitors protected against HgCl(2) effects on DA release.

Influx of extracellular Zn(2+) into the hippocampal CA1 neurons is required for cognitive performance via long-term potentiation.

PubMed

Takeda, A; Suzuki, M; Tempaku, M; Ohashi, K; Tamano, H

2015-09-24

Physiological significance of synaptic Zn(2+) signaling was examined in the CA1 of young rats. In vivo CA1 long-term potentiation (LTP) was induced using a recording electrode attached to a microdialysis probe and the recording region was locally perfused with artificial cerebrospinal fluid (ACSF) via the microdialysis probe. In vivo CA1 LTP was inhibited under perfusion with CaEDTA and ZnAF-2DA, extracellular and intracellular Zn(2+) chelators, respectively, suggesting that the influx of extracellular Zn(2+) is required for in vivo CA1 LTP induction. The increase in intracellular Zn(2+) was chelated with intracellular ZnAF-2 in the CA1 1h after local injection of ZnAF-2DA into the CA1, suggesting that intracellular Zn(2+) signaling induced during learning is blocked with intracellular ZnAF-2 when the learning was performed 1h after ZnAF-2DA injection. Object recognition was affected when training of object recognition test was performed 1h after ZnAF-2DA injection. These data suggest that intracellular Zn(2+) signaling in the CA1 is required for object recognition memory via LTP. Surprisingly, in vivo CA1 LTP was affected under perfusion with 0.1-1μM ZnCl2, unlike the previous data that in vitro CA1 LTP was enhanced in the presence of 1-5μM ZnCl2. The influx of extracellular Zn(2+) into CA1 pyramidal cells has bidirectional action in CA1 LTP. The present study indicates that the degree of extracellular Zn(2+) influx into CA1 neurons is critical for LTP and cognitive performance. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Rapid analysis of glutamate, glutamine and GABA in mice frontal cortex microdialysis samples using HPLC coupled to electrospray tandem mass spectrometry.

PubMed

Defaix, Celine; Solgadi, Audrey; Pham, Thu Ha; Gardier, Alain M; Chaminade, Pierre; Tritschler, Laurent

2018-04-15

In vivo measurement of multiple neurotransmitters is highly interesting but remains challenging in the field of neuroscience. GABA and l-glutamic acid are the major inhibitory and excitatory neurotransmitters, respectively, in the central nervous system, and their changes are related to a variety of diseases such as anxiety and major depressive disorder. This study described a simple method allowing the simultaneous LC-MS/MS quantification of l-glutamic acid, glutamine and GABA. Analytes were acquired from samples of the prefrontal cortex by microdialysis technique in freely moving mice. The chromatographic separation was performed by hydrophilic interaction liquid chromatography (HILIC) with a core-shell ammonium-sulfonic acid modified silica column using a gradient elution with mobile phases consisting of a 25 mM pH 3.5 ammonium formate buffer and acetonitrile. The detection of l-glutamic acid, glutamine and GABA, as well as the internal standards [d6]-GABA and [d5]-glutamate was performed on a triple quadrupole mass spectrometer in positive electrospray ionization and multiple reaction monitoring mode. The limit of quantification was 0.63 ng/ml for GABA, 1.25 ng/ml for l-glutamic acid and 3.15 ng/ml for glutamine, and the intra-day and inter-day accuracy and precision have been assessed for the three analytes. Therefore, the physiological relevance of the method was successfully applied for the determination of basal extracellular levels and potassium-evoked release of these neuroactive substances in the prefrontal cortex in adult awake C57BL/6 mice. Copyright © 2018 Elsevier B.V. All rights reserved.

A multi-enzyme microreactor-based online electrochemical system for selective and continuous monitoring of acetylcholine.

PubMed

Lin, Yuqing; Yu, Ping; Mao, Lanqun

2015-06-07

This study demonstrates an online electrochemical system (OECS) for selective and continuous measurements of acetylcholine (ACh) through efficiently integrating in vivo microdialysis, a multi-enzyme microreactor and an electrochemical detector. A multi-enzyme microreactor was prepared first by co-immobilizing two kinds of enzymes, i.e. choline oxidase (ChOx) and catalase (Cat), onto magnetite nanoparticles and then confining the as-formed nanoparticles into a fused-silica capillary with the assistance of an external magnet. The multi-enzyme microreactor was settled between an in vivo microdialysis sampling system and an electrochemical detector to suppress the interference from choline toward ACh detection. Selective detection of ACh was accomplished using the electrochemical detector with ACh esterase (AChE) and ChOx as the recognition units for ACh and Prussian blue (PB) as the electrocatalyst for the reduction of hydrogen peroxide (H2O2). The current recorded with the OECS was linear with the concentration of ACh (I/nA = -3.90CACh/μM + 1.21, γ = 0.998) within a concentration range of 5 μM to 100 μM. The detection limit, based on a signal-to-noise ratio of 3, was calculated to be 1 μM. Interference investigation demonstrates that the OECS did not produce an observable current response toward physiological levels of common electroactive species, such as ascorbic acid (AA), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and uric acid (UA). The high selectivity and the good linearity in combination with the high stability may enable the OECS developed here as a potential system for continuous monitoring of cerebral ACh release in some physiological and pathological processes.