Apomorphine prevents LPS-induced IL-23 p19 mRNA expression via inhibition of JNK and ATF4 in HAPI cells.

PubMed

Hara, Hirokazu; Kimoto, Dai; Kajita, Miho; Takada, Chisato; Kamiya, Tetsuro; Adachi, Tetsuo

2017-01-15

Inflammation has been reported to be closely related to exaggeration of cerebral ischemia and neurodegenerative diseases. Microglia, resident immune cells in the central nervous system, can be activated in response to neuronal injury and produce proinflammatory cytokines, resulting in further aggravation of neuronal injury. Interleukin (IL)-23, which consists of p19 and IL-12 p40 subunits, has been shown to be involved in brain injury associated with neuroinflammation. Apomorphine (Apo), a nonselective dopamine receptor agonist, has been used for clinical therapy of Parkinson's disease. Besides the pharmacological effect, Apo is known to have pleiotropic biological functions. In this study, to elucidate the effect of Apo on lipopolysaccharide (LPS)-induced IL-23 p19 mRNA expression in microglial cell line HAPI cells, we pretreated cells with various concentrations of Apo (10 - 30μM) for 8, 16, and 24h, followed by exposure to LPS (100ng/ml). Pretreatment with Apo dose- and time-dependently suppressed the induction of IL-23 p19 mRNA. However, this effect of Apo was exerted independently of dopamine receptors. JNK and ATF4, an endoplasmic reticulum (ER) stress-inducible transcription factor, were involved in expression of LPS-induced IL-23 p19 mRNA. Pretreatment with Apo (30μM) for 24h inhibited LPS-induced activation of JNK and the nuclear accumulation of ATF4. Thapsigargin (Tg), an ER stress inducer, stimulated IL-23 p19 mRNA expression via an ATF4 dependent mechanism. We also found that Apo inhibited Tg-induced ATF4 accumulation and IL-23 p19 mRNA expression. Taken together, our findings suggest that Apo exerts anti-inflammatory effects through inhibition of JNK and ATF4 signaling pathways. Copyright © 2016 Elsevier B.V. All rights reserved.

Au nanoparticle-based sensor for apomorphine detection in plasma

PubMed Central

Lucotti, Andrea; Tommasini, Matteo; Trusso, Sebastiano; de Grazia, Ugo; Ciusani, Emilio; Ossi, Paolo M

2015-01-01

Summary Artificially roughened gold surfaces with controlled nanostructure produced by pulsed laser deposition have been investigated as sensors for apomorphine detection aiming at clinical application. The use of such gold surfaces has been optimized using aqueous solutions of apomorphine in the concentration range between 3.3 × 10−4 M and 3.3 × 10−7 M. The experimental parameters have been investigated and the dynamic concentration range of the sensor has been assessed by the selection of two apomorphine surface enhanced Raman scattering (SERS) peaks. The sensor behavior used to detect apomorphine in unfiltered human blood plasma is presented and discussed. PMID:26734514

Ion-exchange and iontophoresis-controlled delivery of apomorphine.

PubMed

Malinovskaja, Kristina; Laaksonen, Timo; Kontturi, Kyösti; Hirvonen, Jouni

2013-04-01

The objective of this study was to test a drug delivery system that combines iontophoresis and cation-exchange fibers as drug matrices for the controlled transdermal delivery of antiparkinsonian drug apomorphine. Positively charged apomorphine was bound to the ion-exchange groups of the cation-exchange fibers until it was released by mobile counter-ions in the external solution. The release of the drug was controlled by modifying either the fiber type or the ionic composition of the external solution. Due to high affinity of apomorphine toward the ion-exchanger, a clear reduction in the in vitro transdermal fluxes from the fibers was observed compared to the respective fluxes from apomorphine solutions. Changes in the ionic composition of the donor formulations affected both the release and iontophoretic flux of the drug. Upon the application of higher co-ion concentrations or co-ions of higher valence in the donor formulation, the release from the fibers was enhanced, but the iontophoretic steady-state flux was decreased. Overall, the present study has demonstrated a promising approach using ion-exchange fibers for controlling the release and iontophoretic transdermal delivery of apomorphine. Copyright © 2012 Elsevier B.V. All rights reserved.

Post-trial apomorphine at an autoreceptor dose level can eliminate apomorphine conditioning and sensitization: support for the critical role of dopamine in re-consolidation.

PubMed

Carrera, Marinete Pinheiro; Carey, Robert J; Cruz Dias, Flávia Regina; dos Santos Sampaio, Maria de Fátima; de Matos, Liana Wermelinger

2013-01-01

Re-exposure to conditioned drug stimuli triggers re-consolidation processes. In the present study post-trial apomorphine treatments were administered in order to interact with the re-consolidation of an apomorphine conditioned/sensitized locomotor response. A low (0.05 mg/kg) and a high (2.0mg/kg) dose were used to inhibit or to enhance dopamine activity, respectively. Initially, groups received 5 daily apomorphine (2.0mg/kg)/vehicle treatments either paired or unpaired to open-field placement. The paired treatments generated a progressive locomotor response. Subsequently, all groups received a 5 min non-drug test for conditioning and a conditioned locomotor response was observed in the paired group. The groups received another apomorphine (2.0mg/kg)/vehicle treatment as a re-induction treatment. At this stage the post-trial protocol was initiated. One set of paired, unpaired and vehicle groups were given a low dose of apomorphine (0.05 mg/kg) post-trial; another set received a high dose of apomorphine (2.0mg/kg) post-trial. The remaining group set received vehicle post-trial. The low dose post-trial treatment eliminated the conditioned and sensitized locomotor response and the high dose post-trial treatment enhanced the conditioned and sensitized locomotor response. The efficacy of the post-trial apomorphine treatments to modify the conditioned and the sensitized response after a brief non-drug exposure to test cues supports the proposition that exteroceptive cues control conditioning and sensitization and that the interoceptive drug cues make little or no associational contribution to apomorphine conditioning and sensitization. In addition, the findings point to the importance of dopamine activation in both the acquisition and re-consolidation of conditioning processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Reversal of apomorphine locomotor sensitization by a single post-conditioning trial treatment with a low autoreceptor dose of apomorphine: a memory re-consolidation approach.

PubMed

Carrera, Marinete Pinheiro; Carey, Robert J; Dias, Flávia Regina Cruz; de Matos, Liana Wermelinger

2011-07-01

Sensitization is a common feature of psychostimulants and sensitization effects are generally considered to be linked to the addictive properties of these drugs. We used a conventional paired/unpaired Pavlovian protocol to induce a context specific sensitization to the locomotor stimulant effect of a high dose of apomorphine (2.0mg/kg). Two days following a 5 session sensitization induction phase, a brief 5min non-drug test for conditioning was conducted. Only the paired groups exhibited locomotor stimulant conditioned response effects. Immediately following this brief test for conditioning, the paired and the unpaired groups received injections of 0.05mg/kg apomorphine, 2.0mg/kg apomorphine or vehicle designed to differentially impact memory re-consolidation of the conditioning. Two days later, all groups received a sensitization challenge test with 2.0mg/kg apomorphine. The 2.0mg/kg apomorphine post-trial treatment potentiated sensitization while the 0.05mg/kg eliminated sensitization. These effects were only observed in the paired groups. The activation of dopaminergic systems by the high dose of apomorphine strengthened the drug/environment association whereas the inhibition of dopamine activity by the low auto-receptor dose eliminated this association. The results point to the importance of conditioning to context specific sensitization and targeting memory re-consolidation of conditioning as a paradigm to modify sensitization. Copyright © 2011 Elsevier Inc. All rights reserved.

Other formulations and future considerations for apomorphine for subcutaneous injection therapy.

PubMed

Koller, William; Stacy, Mark

2004-03-23

This manuscript reviews apomorphine administration in formulations other than intermittent bolus injection, and comments on other potential uses for this unique compound. Continuous sc apomorphine therapy has been shown to alter peak-dose dyskinesia thresholds in advancing patients, and in some instances may replace all other anti-parkinson therapies. In general continuous infusion of sc apomorphine at a rate of 4 mg/h is well tolerated, and has been postulated to be equivalent to approximately 600 mg levodopa/day. This therapy is associated with skin complications, particularly nodule formation, and focal panniculitis is seen in more than 50% of subjects. Optimal dosages for intranasal apomorphine range from 2 to 5 mg per inhalation with benefit seen at 7.5 minutes and duration of effect of 45 to 55 minutes. Side effects included nasal irritation, vestibulitis, dyskinesias, yawning, and nausea. Comparison of 3 mg sc and 30 mg sublingual apomorphine in 9 Parkinson's disease subjects in a blinded cross-over trial found that the time to peak benefit was beyond 40 minutes with sl apomorphine, compared to 21 minutes in the sc preparation. Chronic use of the sublingual formulation was associated with severe stomatitis in half the subjects, and markedly limited the treatment. Rectal administration of apomorphine has been evaluated in limited, usually post-operative settings. Administration of a 200 mg apomorphine rectal suppository resulted in an average time to benefit of 32 minutes with an average duration of 195 minutes. Sedation, nausea and faintness were reported as side effects. Although the diagnostic confirmation potential of this agent has been questioned, the drug may have an important role in evaluating the potential for benefit in the deep brain stimulation surgical setting.

Apomorphine Subcutaneous Injection for the Management of Morning Akinesia in Parkinson's Disease.

PubMed

Isaacson, Stuart; Lew, Mark; Ondo, William; Hubble, Jean; Clinch, Thomas; Pagan, Fernando

2017-01-01

In patients with motor fluctuations complicating Parkinson's disease (PD), delays in time-to-ON with levodopa are common. This open-label study aimed to assess the effect of apomorphine on time-to-ON in PD patients with morning akinesia. The safety population included 127 enrolled patients, and the full analysis set (FAS) included 88 patients. Patients completed a 7-day levodopa baseline period recording their time-to-ON following each morning dose of levodopa. Patients were titrated to an optimal dose of apomorphine (2-6 mg) while taking trimethobenzamide antiemetic therapy. Apomorphine was injected each morning for a 7-day treatment period and time-to-ON was self-recorded in 5-minute blocks. The primary efficacy variable was time-to-ON in the apomorphine treatment period versus the baseline levodopa period. Secondary assessments included and global impression scales. Safety and tolerability were assessed through adverse events (AEs). Patients receiving apomorphine achieved mean ± standard deviation (SD) time-to-ON 23.72 ± 14.55 minutes, reduced from 60.86 ± 18.11 minutes with levodopa ( P < 0.0001). Dose failures (defined as time-to-ON >60 minutes) were more commonly reported with levodopa versus apomorphine (46% vs. 7% of diary entries, respectively). Secondary endpoints supported the primary efficacy findings, with significant improvements from levodopa baseline to apomorphine treatment period (all P < 0.0001). The most common AEs were nausea and dizziness. Most patients who discontinued because of AEs did so in the titration phase. Apomorphine injections significantly reduced time-to-ON in PD patients experiencing delayed onset of their morning levodopa dose, and was well tolerated in most patients. After apomorphine treatment, fluctuating patients with morning akinesia experienced rapid and reliable improvement of time-to-ON.

Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes.

PubMed

Newman-Tancredi, Adrian; Cussac, Didier; Quentric, Yann; Touzard, Manuelle; Verrièle, Laurence; Carpentier, Nathalie; Millan, Mark J

2002-11-01

Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their

Differential involvement of dopamine D-1 and D-2 receptors in the circling behaviour induced by apomorphine, SK & F 38393, pergolide and LY 171555 in 6-hydroxydopamine-lesioned rats.

PubMed

Arnt, J; Hyttel, J

1985-01-01

The antagonistic effect of dopamine (DA) D-1 and D-2 antagonists against circling behaviour induced by various DA agonists in 6-OHDA-lesioned rats has been investigated. DA D-1/D-2 selectivity of agonists in vitro was measured by the stimulatory effect on DA-sensitive adenylate cyclase in rat striatal homogenates (D-1), the inhibitory effect on electrically-induced release of 3H-DA in rabbit striatal slices (D-2) and the affinity to 3H-piflutixol (D-1) and 3H-spiroperidol (D-2) binding sites in rat striatal membranes. The contralateral circling behaviour induced by the DA D-1 agonist SK & F 38393 was blocked by the DA D-1 antagonist, SCH 23390, and by the mixed DA D-1/D-2 antagonist cis(Z)-flupentixol, but was not influenced by the DA D-2 antagonists spiroperidol and clebopride. In contrast, circling behaviour induced by the preferential DA D-2 agonists pergolide and LY 171555 was blocked by clebopride, spiroperidol, and cis(Z)-flupentixol, but weakly or not influenced by SCH 23390. Apomorphine-induced circling behaviour was blocked by cis(Z)-flupentixol, partially antagonized by SCH 23390 and clebopride but not inhibited by spiroperidol, although the time-course of circling was changed. Combinations of SCH 23390 with spiroperidol or clebopride in low doses completely blocked the effect of apomorphine. These results indicate that DA D-1 and D-2 receptors mediate circling behaviour through separate mechanisms which can be independently manipulated with respective agonists and antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Apomorphine, dopamine and phenylethylamine reduce the proportion of phosphorylated insulin receptor substrate 1.

PubMed

Chiarenza, A; Scarselli, M; Novi, F; Lempereur, L; Bernardini, R; Corsini, G U; Maggio, R

2001-12-14

We tested the ability of dopamine, apomorphine, phenylethylamine and pergolide to inhibit the proliferation of fetal calf serum-stimulated human breast cancer (MCF)-7 cells. While the first three compounds were able to block the proliferation of MCF-7 cells, pergolide failed to do so (up to 100 microM). The inhibitory effect of dopamine, apomorphine and phenylethylamine was also evident in serum-starved insulin-stimulated MCF-7 cells. Apomorphine also inhibited the proliferation of the human oestrogen receptor-negative breast cancer (MDA-MB231) and prostate carcinoma (LNCaP) cell lines. In a second set of experiments, we measured the ability of dopamine, apomorphine, phenylethylamine and pergolide to inhibit the phosphorylation (or increase the dephosphorylation) of the insulin receptor substrate (IRS)-1, a major intracellular substrate of the insulin-like growth factor (IGF)-1 receptor. Dopamine, apomorphine and phenylethylamine all reduced to zero the level of phosphorylated IRS-1 with potencies ranging between 0.01 and 1 microM. Finally, we found that fibroblasts from IRS-1 null (-/-) mice were less sensitive to the anti-proliferative effect of apomorphine compared to fibroblasts from wild type-mice, suggesting that the inhibition of IRS-1 phosphorylation by apomorphine is an important aspect of the activity of this compound.

Pavlovian conditioning between co-administered drugs: elicitation of an apomorphine-induced antiparkinsonian response by scopolamine.

PubMed

Carey, R J

1991-01-01

Sprague-Dawley rats with unilateral 6-OHDA substantia nigra lesions were given combined scopolamine (0.5 mg/kg IP) and apomorphine (0.05 mg/kg SC) treatments. In this animal model, scopolamine, when administered separately, induces ipsilateral rotation and apomorphine, contralateral rotation. When these drugs are co-administered at 0.5 mg/kg and 0.05 mg/kg dose levels, respectively, animals rotate in the contralateral direction, creating the opportunity for the stimulus effect of scopolamine to become associated with the response effect of apomorphine. In tests with scopolamine (0.5 mg/kg), animals that previously had scopolamine and apomorphine co-administered rotated contralaterally in the test chamber, thereby behaving as if they had received apomorphine. Thus, scopolamine exhibited a functionally acquired conditioned stimulus (CS) property by eliciting the apomorphine response of contralateral rotation as a conditioned response. This acquired CS property was extinguished with separate scopolamine trials and reacquired following one scopolamine-apomorphine co-administration trial.

Effects of local infusions of apomorphine on the extracellular citrulline level in the striatum: Involvement of D1 and D2 dopamine receptors.

PubMed

Savel'ev, S A

2006-11-01

Studies using vital microdialysis and high-performance liquid chromatography showed that local infusion of the NO synthase inhibitor N-nitro-L-arginine (1 mM) into the striatum decreased, while infusion of the dopamine receptor agonist apomorphine (100 microM) increased the level of citrulline (a side product of nitric oxide synthesis) in the intercellular space of this structure in Sprague-Dawley rats. The increase in the citrulline level induced by infusions of apomorphine was completely prevented by local infusions of N-nitro-L-arginine (1 mM) and raclopride (10 microm), a dopamine D2 receptor blocker, but not by infusion of SCH-23390 (50 microm), a dopamine D1 receptor blocker. These data suggest that the increase in extracellular citrulline in the striatum induced by dopaminergic stimulation results from local increases in NO synthase activity and that this effect involves D2, but not D1 dopamine receptors.

The Role of Dopamine in Reinforcement: Changes in Reinforcement Sensitivity Induced by D[subscript 1]-Type, D[subscript 2]-Type, and Nonselective Dopamine Receptor Agonists

ERIC Educational Resources Information Center

Bratcher, Natalie A.; Farmer-Dougan, Valeri; Dougan, James D.; Heidenreich, Byron A.; Garris, Paul A.

2005-01-01

Dose-dependent changes in sensitivity to reinforcement were found when rats were treated with low, moderate, and high doses of the partial dopamine D[subscript 1]-type receptor agonist SKF38393 and with the nonselective dopamine agonist apomorphine, but did not change when rats were treated with similar doses of the selective dopamine D[subscript…

Differential agonist and inverse agonist profile of antipsychotics at D2L receptors coupled to GIRK potassium channels.

PubMed

Heusler, Peter; Newman-Tancredi, Adrian; Castro-Fernandez, Annabelle; Cussac, Didier

2007-03-01

The D(2) dopaminergic receptor represents a major target of antipsychotic drugs. Using the coupling of the human D(2long) (hD(2L)) receptor to G protein-coupled inward rectifier potassium (GIRK) channels in Xenopus laevis oocytes, we examined the activity of antipsychotic agents of different classes - typical, atypical, and a "new generation" of compounds, exhibiting a preferential D(2) and 5-HT(1A) receptor profile. When the hD(2L) receptor was coexpressed with GIRK channels, a series of reference compounds exhibited full agonist (dopamine, and quinpirole), partial agonist (apomorphine, (-)3-PPP, and (+)-UH232) or inverse agonist (raclopride, and L741626) properties. Sarizotan exhibited only very weak partial agonist action. At higher levels of receptor cRNA injected per oocyte, both partial agonist activity and inverse agonist properties were generally more pronounced. The inverse agonist action of L741626 was reversed by interaction with sarizotan, thus confirming the constitutive activity of wild-type hD(2L) receptors in the oocyte expression system. When antipsychotic agents were tested for their actions at the hD(2L) receptor, typical (haloperidol) as well as atypical (nemonapride, ziprasidone, and clozapine) compounds acted as inverse agonists. In contrast, among D(2)/5-HT(1A) antipsychotics, only SLV313 and F15063 behaved as inverse agonists, whilst the other members of this group (bifeprunox, SSR181507 and the recently marketed antipsychotic, aripiprazole) exhibited partial agonist properties. Thus, the X. laevis oocyte expression system highlights markedly different activity of antipsychotics at the hD(2L) receptor. These differential properties may translate to distinct therapeutic potential of these compounds.

Evaluating the Efficacy of Nocturnal Continuous Subcutaneous Apomorphine Infusion in Sleep Disorders in Advanced Parkinson's Disease: The APO-NIGHT Study.

PubMed

Fernández-Pajarín, Gustavo; Sesar, Ángel; Ares, Begoña; Castro, Alfonso

2016-10-19

There are not many data about the beneficial effect of nocturnal continuous subcutaneous apomorphine infusion (NCSAI) over sleep disturbances in advanced Parkinson's disease (PD). Evaluate the effect of the NCSAI in sleeping problems and insomnia due to nocturnal hypokinesia inadvanced PD. We assessed 17 advanced PD patients with several sleep disturbances measured by SCOPA-SLEEP and PDSS scales. All the patients were on apomorphine infusion during daytime. This therapy was extended to nighttime. We evaluated the patients before the onset and after six weeks with NCSAI. NCSAI allowed highly significant improvements in SCOPA-SLEEP and PDSS scales (p<0.0001), and daytime somnolence. NCSAI was well tolerated with no major adverse effects were noticed. This study shows and confirms the efficacy of NCSAI on the sleep disturbances related to advanced PD. We provide an easy protocol to start this therapy.

Sex differences in the response to apomorphine in rats.

PubMed

Masur, J; Boerngen, R; Tufik, S

1980-01-01

The response of male and female rats to the hypothermic and verticalization effect (climbing behavior) induced by different doses of apomorphine was studied. A clear sex difference was observed, males showing more verticalization than females. Conversely the females showed a greater decrease in body temperature than males. The verticalization response was also studied in rats of both sexes at seven different ages, varying from 15 to 100 days. At the earlier ages, both groups presented low levels of verticalization. Mature males (60-100 days of age) increased the verticalization response to apomorphine.

Rotigotine is a potent agonist at dopamine D1 receptors as well as at dopamine D2 and D3 receptors.

PubMed

Wood, Martyn; Dubois, Vanessa; Scheller, Dieter; Gillard, Michel

2015-02-01

Rotigotine acts as a dopamine receptor agonist with high affinity for the dopamine D2, D3, D4 and D5 receptors but with a low affinity for the dopamine D1 receptor. We have investigated this further in radioligand binding and functional studies and compared the profile of rotigotine with that of other drugs used in the treatment of Parkinson's disease (PD). The binding of rotigotine to human dopamine D1, D2, D3, D4 and D5 receptors was determined in radioligand binding studies using [(3)H]rotigotine and compared with that of standard antagonist radioligands. Functional interactions of rotigotine with human dopamine receptors was also determined. [(3)H]rotigotine can be used as an agonist radioligand to label all dopamine receptor subtypes and this can be important to derive agonist affinity estimates. Rotigotine maintains this high affinity in functional studies at all dopamine receptors especially D1, D2 and D3 receptors and, to a lesser extent, D4 and D5 receptors. Rotigotine, like apomorphine but unlike ropinirole and pramipexole, was a potent agonist at all dopamine receptors. Rotigotine is a high-potency agonist at human dopamine D1, D2 and D3 receptors with a lower potency at D4 and D5 receptors. These studies differentiate rotigotine from conventional dopamine D2 agonists, used in the treatment of PD, such as ropinirole and pramipexole which lack activity at the D1 and D5 receptors, but resembles that of apomorphine which has greater efficacy in PD than other dopamine agonists but has suboptimal pharmacokinetic properties. © 2014 The British Pharmacological Society.

Rotigotine is a potent agonist at dopamine D1 receptors as well as at dopamine D2 and D3 receptors

PubMed Central

Wood, Martyn; Dubois, Vanessa; Scheller, Dieter; Gillard, Michel

2015-01-01

Background and Purpose Rotigotine acts as a dopamine receptor agonist with high affinity for the dopamine D2, D3, D4 and D5 receptors but with a low affinity for the dopamine D1 receptor. We have investigated this further in radioligand binding and functional studies and compared the profile of rotigotine with that of other drugs used in the treatment of Parkinson's disease (PD). Experimental Approach The binding of rotigotine to human dopamine D1, D2, D3, D4 and D5 receptors was determined in radioligand binding studies using [3H]rotigotine and compared with that of standard antagonist radioligands. Functional interactions of rotigotine with human dopamine receptors was also determined. Key Results [3H]rotigotine can be used as an agonist radioligand to label all dopamine receptor subtypes and this can be important to derive agonist affinity estimates. Rotigotine maintains this high affinity in functional studies at all dopamine receptors especially D1, D2 and D3 receptors and, to a lesser extent, D4 and D5 receptors. Rotigotine, like apomorphine but unlike ropinirole and pramipexole, was a potent agonist at all dopamine receptors. Conclusions and Implications Rotigotine is a high-potency agonist at human dopamine D1, D2 and D3 receptors with a lower potency at D4 and D5 receptors. These studies differentiate rotigotine from conventional dopamine D2 agonists, used in the treatment of PD, such as ropinirole and pramipexole which lack activity at the D1 and D5 receptors, but resembles that of apomorphine which has greater efficacy in PD than other dopamine agonists but has suboptimal pharmacokinetic properties. PMID:25339241

Dimethylaminoethanol (deanol): effect on apomorphine-induced stereotypy and an animal model of tardive dyskinesia.

PubMed

Davis, K L; Hollister, L E; Vento, A L; Beilstein, B A; Rosekind, G R

1979-05-25

Dimethylaminoethanol (DMAE) was administered acutely to rats subsequently injected with spomorphine. A dose of 80 mg of DMAE had no effect on the severity of apomorphine-induced stereotypy. However, 160 mg of DMAE significantly diminished the severity of apomorphine-induced stereotypy. This dose of DMAE did not significantly alter spontaneous locomotor activity. DMAE did not reduced apomorphine-induced stereotypy in animals previously exposed to haloperidol and presumed to have postsynaptic dopamine receptor supersensitivity. These results with DMAE are contrasted with the effects of choline chloride, and suggest that choline chloride may be more effective than DMAE at augmenting striatal cholinergic activity.

Treatment with a GnRH receptor agonist, but not the GnRH receptor antagonist degarelix, induces atherosclerotic plaque instability in ApoE(-/-) mice.

PubMed

Knutsson, Anki; Hsiung, Sabrina; Celik, Selvi; Rattik, Sara; Mattisson, Ingrid Yao; Wigren, Maria; Scher, Howard I; Nilsson, Jan; Hultgårdh-Nilsson, Anna

2016-05-18

Androgen-deprivation therapy (ADT) for prostate cancer has been associated with increased risk for development of cardiovascular events and recent pooled analyses of randomized intervention trials suggest that this primarily is the case for patients with pre-existing cardiovascular disease treated with gonadotropin-releasing hormone receptor (GnRH-R) agonists. In the present study we investigated the effects of the GnRH-R agonist leuprolide and the GnRH-R antagonist degarelix on established atherosclerotic plaques in ApoE(-/-) mice. A shear stress modifier was used to produce both advanced and more stable plaques in the carotid artery. After 4 weeks of ADT, increased areas of necrosis was observed in stable plaques from leuprolide-treated mice (median and IQR plaque necrotic area in control, degarelix and leuprolide-treated mice were 0.6% (IQR 0-3.1), 0.2% (IQR 0-4.4) and 11.0% (IQR 1.0-19.8), respectively). There was also evidence of increased inflammation as assessed by macrophage immunohistochemistry in the plaques from leuprolide-treated mice, but we found no evidence of such changes in plaques from control mice or mice treated with degarelix. Necrosis destabilizes plaques and increases the risk for rupture and development of acute cardiovascular events. Destabilization of pre-existing atherosclerotic plaques could explain the increased cardiovascular risk in prostate cancer patients treated with GnRH-R agonists.

Agonistic antibody to angiotensin II type 1 receptor accelerates atherosclerosis in ApoE-/- mice

PubMed Central

Li, Weijuan; Chen, Yaoqi; Li, Songhai; Guo, Xiaopeng; Zhou, Wenping; Zeng, Qiutang; Liao, Yuhua; Wei, Yumiao

2014-01-01

This study aimed to investigate the effects of agonistic antibody to angiotensin II type 1 receptor (AT1-AA) on atherosclerosis in male ApoE-/- mice which were employed to establish the animal models of AT1-AA in two ways. In the first group, mice were injected subcutaneously with conjugated AT1 peptide at multiple sites; in the second group, mice were infused with AT1-AA prepared from rabbits that were treated with AT1 peptide intraperitoneally. Mice in each group were further randomly divided into five subgroups and treated with AT1 peptide/AT1-AA, AT1 peptide/AT1-AA plus valsartan, AT1 peptide/AT1-AA plus fenofibrate, AT1 peptide/ AT1-AA plus pyrrolidine dithiocarbamate (PDTC) and control vehicle, respectively. Antibodies were detected in mice (except for mice in control group). Aortic atherosclerotic lesions were assessed by oil red O staining, while plasma CRP, TNF-α, nuclear factor-kappa B (NF-κB) and H2O2 were determined by ELISA. CCR2 (the receptor of MCP-1), macrophages, and smooth muscle cells were detected by immunohistochemistry. P47phox, MCP-1 and eNOS were detected by RT-PCR, while P47phox, NF-κB and MCP-1 were detected by Western blot assay. The aortic atherosclerotic lesions were significantly increased in AT1 peptide/AT1-AA treated mice, along with simultaneous increases in inflammatory parameters. However, mice treated with valsartan, fenofibrate or PDTC showed alleviated progression of atherosclerosis and reductions in inflammatory parameters. Thus, AT1-AA may accelerate aortic atherosclerosis in ApoE-/- mice, which is mediated, at least in part, by the inflammatory reaction involving nicotinamide-adenine dinucleotide phosphate oxidase, reactive oxygen species, and NF-κB. In addition, valsartan, fenofibrate and PDTC may inhibit the AT1-AA induced atherosclerosis. PMID:25628779

Low tryptophan diet decreases brain serotonin and alters response to apomorphine

NASA Technical Reports Server (NTRS)

Sahakian, B. J.; Wurtman, R. J.; Barr, J. K.; Millington, W. R.; Chiel, H. J.

1979-01-01

The role of the serotoninergic system in the regulation of apomorphine-induced behavior, a behavior primarily controlled by dopaminergic neurotransmission, was investigated in rats fed on a low tryptophan diet since weaning. It was found that reductions in brain seritonin (5-HT) produced by diet result in decreased stereotypy after apomorphine administration. This indicates that although stereotyped behavior is primarily mediated by dopaminergic mechanisms, it can also be modulated by other neurotransmitter including 5-HT. It was also shown that changes in brain seritonin levels can affect psychomotor stimulant-induced hypothermia.

Binding Interactions of Dopamine and Apomorphine in D2High and D2Low States of Human Dopamine D2 Receptor Using Computational and Experimental Techniques.

PubMed

Durdagi, Serdar; Salmas, Ramin Ekhteiari; Stein, Matthias; Yurtsever, Mine; Seeman, Philip

2016-02-17

We have recently reported G-protein coupled receptor (GPCR) model structures for the active and inactive states of the human dopamine D2 receptor (D2R) using adrenergic crystal structures as templates. Since the therapeutic concentrations of dopamine agonists that suppress the release of prolactin are the same as those that act at the high-affinity state of the D2 receptor (D2High), D2High in the anterior pituitary gland is considered to be the functional state of the receptor. In addition, the therapeutic concentrations of anti-Parkinson drugs are also related to the dissociation constants in the D2High form of the receptor. The discrimination between the high- and low-affinity (D2Low) components of the D2R is not obvious and requires advanced computer-assisted structural biology investigations. Therefore, in this work, the derived D2High and D2Low receptor models (GPCR monomer and dimer three-dimensional structures) are used as drug-binding targets to investigate binding interactions of dopamine and apomorphine. The study reveals a match between the experimental dissociation constants of dopamine and apomorphine at their high- and low-affinity sites of the D2 receptor in monomer and dimer and their calculated dissociation constants. The allosteric receptor-receptor interaction for dopamine D2R dimer is associated with the accessibility of adjacent residues of transmembrane region 4. The measured negative cooperativity between agonist ligand at dopamine D2 receptor is also correctly predicted using the D2R homodimerization model.

Sensitive quantification of apomorphine in human plasma using a LC-ESI-MS-MS method.

PubMed

Abe, Emuri; Alvarez, Jean-Claude

2006-06-01

An analytical method based on liquid chromatography coupled with ion trap mass spectrometry (MS) detection with electrospray ionization interface has been developed for the identification and quantification of apomorphine in human plasma. Apomorphine was isolated from 0.5 mL of plasma using a liquid-liquid extraction with diethyl ether and boldine as internal standard, with satisfactory extraction recoveries. Analytes were separated on a 5-microm C18 Highpurity (Thermohypersil) column (150 mm x 2.1 mm I.D.) maintained at 30 degrees C, coupled to a precolumn (C18, 5-microm, 10 mm x 2.0 mm I.D., Thermo). The elution was achieved isocratically with a mobile phase of 2 mM NH4COOH buffer pH 3.8/acetonitrile (50/50, vol/vol) at a flow rate of 200 microL per minute. Data were collected either in full-scan MS mode at m/z 150 to 500 or in full-scan tandem mass spectrometry mode, selecting the [M+H]ion at m/z 268.0 for apomorphine and m/z 328.0 for boldine. The most intense daughter ion of apomorphine (m/z 237.1) and boldine (m/z 297.0) were used for quantification. Retention times were 2.03 and 2.11 minutes for boldine and apomorphine, respectively. Calibration curves were linear in the 0.025 to 20 ng/mL range. The limits of detection and quantification were 0.010 ng/mL and 0.025 ng/mL, respectively. Accuracy and precision of the assay were measured by analyzing 54 quality control samples for 3 days. At concentrations of 0.075, 1.5, and 15 ng/mL, intraday precisions were less than 10.1%, 5.3%, and 3.8%, and interday precisions were less than 4.8%, 6.6%, and 6.5%, respectively. Accuracies were in the 99.5 to 104.2% range. An example of a patient who was given 6 mg of apomorphine subcutaneously is shown, with concentrations of 14.1 ng/mL after 30 minutes and 0.20 ng/mL after 6 hours. The method described enables the unambiguous identification and quantification of apomorphine with very good sensitivity using only 0.5 mL of sample, and is very convenient for therapeutic drug

Novel liquid chromatographic assay for the low-level determination of apomorphine in plasma.

PubMed

Priston, M J; Sewell, G J

1996-05-31

A novel HPLC assay which is rapid, reproducible and sensitive has been developed for the analysis of apomorphine in plasma. The assay incorporates boldine as an internal standard, and uses solid-phase extraction on C18 mini-columns for sample clean-up and concentration, so enabling quantitation of apomorphine at 500 pg/ml using fluorescence detection (lambda(ex) 270 nm, lambda(em) 450 nm). The HPLC assay comprised a 25 cm-long Techopak C18 column and a mobile phase of (0.25 M sodium dihydrogen phosphate plus 0.25% heptane sulphonic acid, to pH 3.3 with orthophosphoric acid) containing 30% (v/v) methanol and 0.003% (w/v) EDTA, run at a flow-rate of 1.5 ml/min. Calibration plots prepared in plasma were linear over the range 1-30 ng/ml, (limit of quantitation (LOQ) = 490 pg/ml) with R.S.D. of 0.05% and R.E. of 5.0% at the level of 1 ng/ml. Preliminary pharmacokinetic data from two patients given apomorphine by 12 h subcutaneous infusion (patient A dose = 35 mg and patient B dose = 141 mg) showed apomorphine elimination from plasma to fit a two-compartment model, with initial half-lives of 8.2 and 46.6 min, elimination half-lives of 76.4 and 166.5 min and area under the plasma concentration-time curve (AUC) values of 236 and 405 ng h/ml, respectively.

Effect of non-selective dopaminergic receptor agonist on disrupted maternal behavior in olfactory bulbectomized mice.

PubMed

Sato, Atsushi; Nakagawasai, Osamu; Tan-No, Koichi; Onogi, Hiroshi; Niijima, Fukie; Tadano, Takeshi

2010-07-11

Olfactory bulbectomy (OBX) animals are considered a putative model of depression that produces behavioral, physiological, and neurochemical alterations resembling clinical depression. Depression is a critical cause of child abuse and neglect, and it has been reported that maternal behavior involves dopaminergic neurons of the mesolimbic pathway. In this study, we investigated the effect of apomorphine, a non-selective dopaminergic receptor agonist, on maternal behavior to examine the influence of activated brain dopaminergic function in OBX mice. In addition, we conducted the sucrose preference test to examine the reward system which has a critical relationship to mesolimbic dopaminergic function and maternal behavior. Maternal behavior was observed on postnatal day (PND) 0 and 4. OBX female mice showed a reduction in sucrose preference 2 weeks post surgery. OBX dams showed maternal behavior deficits on PND 0, and these deficits were ameliorated by administration of apomorphine. These results suggest that maternal behavior deficits in OBX dams may involve brain hypodopaminergic function in the central nervous system induced by OBX. Copyright 2010 Elsevier B.V. All rights reserved.

Effectiveness and adverse effects of the use of apomorphine and 3% hydrogen peroxide solution to induce emesis in dogs.

PubMed

Khan, Safdar A; McLean, Mary Kay; Slater, Margaret; Hansen, Steven; Zawistowski, Stephen

2012-11-01

To determine the effectiveness and adverse effects of apomorphine and 3% hydrogen peroxide solution used for emesis in dogs. Prospective observational study. 147 dogs that received apomorphine (IV or placed in the conjunctival sac) or 3% hydrogen peroxide solution (PO) to induce emesis after exposure to toxic agents. Data regarding signalment; agent information; type, dose, route, and number of emetic administrations; whether emesis was successful; number of times emesis occurred; percentage of ingested agent recovered; and adverse effects were collected via telephone during American Society for the Prevention of Cruelty to Animals Animal Poison Control Center operations and stored in a database for analysis. Mann-Whitney and Fisher exact tests were used to evaluate emetic success rates. Apomorphine and 3% hydrogen peroxide solution successfully induced emesis in 59 of 63 (94%) and 76 of 84 (90%) of dogs, respectively. Mean time to onset of emesis after the first dose of emetic was 14.5 and 18.6 minutes when hydrogen peroxide (n = 37) and apomorphine (31) were used, respectively, with mean durations of 42 and 27 minutes, respectively. Mean estimates for recovery of ingested agents were 48% for hydrogen peroxide and 52% for apomorphine. Adverse effects were reported in 16 of 112 (14%) dogs for which information was available. 3% hydrogen peroxide solution and apomorphine effectively induced emesis in dogs when used as directed. Emesis occurred within minutes after administration and helped recover substantial amounts of ingested agents. Adverse effects of both emetics were considered mild and self-limiting.

The Many Faces of Apomorphine: Lessons from the Past and Challenges for the Future.

PubMed

Auffret, Manon; Drapier, Sophie; Vérin, Marc

2018-06-01

Apomorphine is now recognized as the oldest antiparkinsonian drug on the market. Though still underused, it is increasingly prescribed in Europe for patients with advanced Parkinson's disease (PD) with motor fluctuations. However, its history is far from being limited to movement disorders. This paper traces the history of apomorphine, from its earliest empirical use, to its synthesis, pharmacological development, and numerous indications in human and veterinary medicine, in light of its most recent uses and newest challenges. From shamanic rituals in ancient Egypt and Mesoamerica, to the treatment of erectile dysfunction, from being discarded as a pharmacological tool to becoming an essential antiparkinsonian drug, the path of apomorphine in the therapeutic armamentarium has been tortuous and punctuated by setbacks and groundbreaking discoveries. Throughout history, three main clinical indications stood out: emetic (gastric emptying, respiratory disorders, aversive conditioning), sedative (mental disorders, clinical anesthesia, alcoholism), and antiparkinsonian (fluctuations). New indications may arise in the future, both in PD (palliative care, nonmotor symptoms, withdrawal of oral dopaminergic medication), and outside PD, with promising work in neuroprotection or addiction.

Apomorphine conditioning and sensitization: the paired/unpaired treatment order as a new major determinant of drug conditioned and sensitization effects.

PubMed

de Matos, Liana Wermelinger; Carey, Robert J; Carrera, Marinete Pinheiro

2010-09-01

Repeated treatments with psychostimulant drugs generate behavioral sensitization. In the present study we employed a paired/unpaired protocol to assess the effects of repeated apomorphine (2.0 mg/kg) treatments upon locomotion behavior. In the first experiment we assessed the effects of conditioning upon apomorphine sensitization. Neither the extinction of the conditioned response nor a counter-conditioning procedure in which we paired an inhibitory treatment (apomorphine 0.05 mg/kg) with the previously established conditioned stimulus modified the sensitization response. In the second experiment, we administered the paired/unpaired protocol in two phases. In the second phase, we reversed the paired/unpaired protocol. Following the first phase, the paired group alone exhibited conditioned locomotion in the vehicle test and a sensitization response. In the second phase, the initial unpaired group which received 5 paired apomorphine trials during the reversal phase did not develop a conditioned response but developed a potentiated sensitization response. This disassociation of the conditioned response from the sensitization response is attributed to an apomorphine anti-habituation effect that can generate a false positive Pavlovian conditioned response effect. The potentiated sensitization response induced by the treatment reversal protocol points to an important role for the sequential experience of the paired/unpaired protocol in behavioral sensitization. 2010 Elsevier Inc. All rights reserved.

Theranostic liposomes loaded with quantum dots and apomorphine for brain targeting and bioimaging

PubMed Central

Wen, Chih-Jen; Zhang, Li-Wen; Al-Suwayeh, Saleh A; Yen, Tzu-Chen; Fang, Jia-You

2012-01-01

Quantum dots (QDs) and apomorphine were incorporated into liposomes to eliminate uptake by the liver and enhance brain targeting. We describe the preparation, physicochemical characterization, in vivo bioimaging, and brain endothelial cell uptake of the theranostic liposomes. QDs and the drug were mainly located in the bilayer membrane and inner core of the liposomes, respectively. Spherical vesicles with a mean diameter of ~140 nm were formed. QDs were completely encapsulated by the vesicles. Nearly 80% encapsulation percentage was achieved for apomorphine. A greater fluorescence intensity was observed in mouse brains treated with liposomes compared to free QDs. This result was further confirmed by ex vivo imaging of the organs. QD uptake by the heart and liver was reduced by liposomal incorporation. Apomorphine accumulation in the brain increased by 2.4-fold after this incorporation. According to a hyperspectral imaging analysis, multifunctional liposomes but not the aqueous solution carried QDs into the brain. Liposomes were observed to have been efficiently endocytosed into bEND3 cells. The mechanisms involved in the cellular uptake were clathrin- and caveola-mediated endocytosis, which were energy-dependent. To the best of our knowledge, our group is the first to develop liposomes with a QD-drug hybrid for the aim of imaging and treating brain disorders. PMID:22619515

Theranostic liposomes loaded with quantum dots and apomorphine for brain targeting and bioimaging.

PubMed

Wen, Chih-Jen; Zhang, Li-Wen; Al-Suwayeh, Saleh A; Yen, Tzu-Chen; Fang, Jia-You

2012-01-01

Quantum dots (QDs) and apomorphine were incorporated into liposomes to eliminate uptake by the liver and enhance brain targeting. We describe the preparation, physicochemical characterization, in vivo bioimaging, and brain endothelial cell uptake of the theranostic liposomes. QDs and the drug were mainly located in the bilayer membrane and inner core of the liposomes, respectively. Spherical vesicles with a mean diameter of ~140 nm were formed. QDs were completely encapsulated by the vesicles. Nearly 80% encapsulation percentage was achieved for apomorphine. A greater fluorescence intensity was observed in mouse brains treated with liposomes compared to free QDs. This result was further confirmed by ex vivo imaging of the organs. QD uptake by the heart and liver was reduced by liposomal incorporation. Apomorphine accumulation in the brain increased by 2.4-fold after this incorporation. According to a hyperspectral imaging analysis, multifunctional liposomes but not the aqueous solution carried QDs into the brain. Liposomes were observed to have been efficiently endocytosed into bEND3 cells. The mechanisms involved in the cellular uptake were clathrin- and caveola-mediated endocytosis, which were energy-dependent. To the best of our knowledge, our group is the first to develop liposomes with a QD-drug hybrid for the aim of imaging and treating brain disorders.

F15063, a compound with D2/D3 antagonist, 5-HT1A agonist and D4 partial agonist properties: (II) Activity in models of positive symptoms of schizophrenia

PubMed Central

Depoortère, R; Bardin, L; Auclair, A L; Kleven, M S; Prinssen, E; Colpaert, F; Vacher, B; Newman-Tancredi, A

2007-01-01

Background and purpose: F15063 is a high affinity D2/D3 antagonist, D4 partial agonist, and high efficacy 5-HT1A agonist, with little affinity (40-fold lower than for D2 receptors) at other central targets. Here, the profile of F15063 was evaluated in models of positive symptoms of schizophrenia and motor side-effects. Experimental approach: Rodent behavioural tests were based on reversal of hyperactivity induced by psychostimulants and on measures of induction of catalepsy and ‘serotonin syndrome'. Key results: F15063 potently (ED50s: 0.23 to 1.10 mg kg−1 i.p.) reversed methylphenidate-induced stereotyped behaviors, blocked d-amphetamine and ketamine hyperlocomotion, attenuated apomorphine-induced prepulse inhibition (PPI) deficits, and was active in the conditioned avoidance test. In mice, it reversed apomorphine-induced climbing (ED50 = 0.30 mg kg−1 i.p.). F15063, owing to its 5-HT1A agonism, did not produce (ED50 > 40 mg kg−1 i.p.) catalepsy in rats and mice, a behavior predictive of occurrence of extra-pyramidal syndrome (EPS) in man. This absence of cataleptogenic activity was maintained upon sub-chronic treatment of rats for 5 days at 40 mg kg−1 p.o. Furthermore, F15063 did not induce the ‘serotonin syndrome' in rats (flat body posture and forepaw treading: ED50 >32 mg kg−1 i.p.). Conclusions and implications: F15063 conformed to the profile of an atypical antipsychotic, with potent actions in models of hyperdopaminergic activity but without inducing catalepsy. These data suggest that F15063 may display potent antipsychotic actions with low EPS liability. This profile is complemented by a favourable profile in rodent models of negative symptoms and cognitive deficits of schizophrenia (companion paper). PMID:17375086

The oxidation of apomorphine and other catechol compounds by horseradish peroxidase: relevance to the measurement of dihydropteridine reductase activity.

PubMed

Milstien, S; Kaufman, S

1987-03-19

It has been reported by Shen et al. (Shen, R.-S., Smith, R.V., Davis, P.J. and Abell, C.W. (1984) J. Biol. Chem. 259, 8894-9000) that apomorphine and dopamine are potent, non-competitive inhibitors of quinonoid dihydropteridine reductase. In this paper we show that apomorphine, dopamine and other catechol-containing compounds are oxidized rapidly to quinones by the horseradish peroxidase-H2O2 system which is used to generate the quinonoid dihydropterin substrate. These quinones react non-enzymatically with reduced pyridine nucleotides, depleting the other substrate of dihydropteridine reductase. When true initial rates of dihydropteridine reductase-dependent reduction of quinonoid dihydropterins are measured, neither apomorphine nor any other catechol-containing compound that has been tested has been found to inhibit dihydropteridine reductase.

Role of dopamine D4 receptors in copulatory behavior: Studies with selective D4 agonists and antagonists in male rats.

PubMed

Sanna, Fabrizio; Contini, Andrea; Melis, Maria Rosaria; Argiolas, Antonio

2015-10-01

Dopamine influences the anticipatory and consummatory phases of sexual behavior, by acting on receptors of the D2 family (D2, D3 and D4) and in particular of the D2 subtype, although evidence for a role of D4 receptors in erectile function and copulatory behavior is also available. In order to clarify such a role of D4 receptors, the effect of selective D4 receptor agonists and antagonists on copulatory behavior of sexually potent male rats in classic copulation tests with a receptive female, was compared with that of apomorphine and haloperidol, a classic dopamine receptor agonist and antagonist, respectively. PD-168,077 (0.05-0.2mg/kg) and ABT-724 (0.01-0.04mg/kg), two selective D4 receptor agonists, given subcutaneously, improved dose-dependently copulatory behavior as shown by the decrease of mount frequency and post ejaculatory interval induced by PD-168,077, and of mount frequency, ejaculation latency, post ejaculatory and inter intromission intervals induced by ABT-724, and by the increase of ejaculation frequency and copulatory efficacy induced by both drugs. Conversely, L-745,870 (1-5mg/kg), a selective D4 receptor antagonist, given intraperitoneally, impaired dose-dependently copulatory behavior, as shown by the increase in intromission and ejaculation latencies, mount frequency, post ejaculatory interval and the decrease in ejaculation frequency and copulatory efficacy induced by this drug. L-745,870 (5mg/kg) administered before PD-168,077 (0.2mg/kg) or ABT-724 (0.04mg/kg), also abolished completely the facilitatory effects of both PD-168,077 and ABT-724 on sexual behavior. These results confirm the involvement of D4 receptors in specific aspects of male rat copulatory behavior that overlap only partially with those influenced by apomorphine and haloperidol. Copyright © 2015 Elsevier Inc. All rights reserved.

Winter day lengths counteract stimulatory effects of apomorphine and yohimbine on sexual behavior of male Syrian hamsters.

PubMed

Piekarski, David J; Jarjisian, Stephan G; Zucker, Irving

2012-08-01

Yohimbine and apomorphine selectively act on noradrenergic and dopaminergic neural substrates to augment male sexual behavior (MSB) in several rodent species. The present study assessed whether these drugs can overcome the suppressive effects of short winter-like day lengths on MSB. Yohimbine treatments that markedly increase copulatory behavior of male hamsters in long days were completely ineffective in facilitating MSB when injected after gonadal regression induced by 16 wks of short day lengths and after complete gonadal recrudescence after 32 wks of short days; apomorphine was similarly ineffective. The brain circuit that mediates MSB either may be less responsive to yohimbine and apomorphine in short than long days, or these drugs may not produce equivalent neurotransmitter changes in the two day lengths. After 32 wks of short-day treatment, all males had undergone testicular recrudescence and successfully ejaculated on initial tests with sexually receptive females after a hiatus of at least 4 mo during which they were denied mating opportunities. This suggests that overwintering males in the field are in a state of reproductive readiness at the outset of spring conditions favorable for survival of offspring.

Kinetic characterization of ebselen, chelerythrine and apomorphine as glutaminase inhibitors.

PubMed

Thomas, Ajit G; Rojas, Camilo; Tanega, Cordelle; Shen, Min; Simeonov, Anton; Boxer, Matthew B; Auld, Douglas S; Ferraris, Dana V; Tsukamoto, Takashi; Slusher, Barbara S

2013-08-23

Glutaminase catalyzes the hydrolysis of glutamine to glutamate and plays a central role in the proliferation of neoplastic cells via glutaminolysis, as well as in the generation of excitotoxic glutamate in central nervous system disorders such as HIV-associated dementia (HAD) and multiple sclerosis. Both glutaminase siRNA and glutaminase inhibition have been shown to be effective in in vitro models of cancer and HAD, suggesting a potential role for small molecule glutaminase inhibitors. However, there are no potent, selective inhibitors of glutaminase currently available. The two prototypical glutaminase inhibitors, BPTES and DON, are either insoluble or non-specific. In a search for more drug-like glutaminase inhibitors, we conducted a screen of 1280 in vivo active drugs (Library of Pharmacologically Active Compounds (LOPAC(1280))) and identified ebselen, chelerythrine and (R)-apomorphine. The newly identified inhibitors exhibited 10 to 1500-fold greater affinities than DON and BPTES and over 100-fold increased efficiency of inhibition. Although non-selective, it is noteworthy that the affinity of ebselen for glutaminase is more potent than any other activity yet described. It is possible that the previously reported biological activity seen with these compounds is due, in part, to glutaminase inhibition. Ebselen, chelerythrine and apomorphine complement the armamentarium of compounds to explore the role of glutaminase in disease. Copyright © 2013 Elsevier Inc. All rights reserved.

Liraglutide, a GLP-1 receptor agonist, inhibits vascular smooth muscle cell proliferation by enhancing AMP-activated protein kinase and cell cycle regulation, and delays atherosclerosis in ApoE deficient mice.

PubMed

Jojima, Teruo; Uchida, Kohsuke; Akimoto, Kazumi; Tomotsune, Takanori; Yanagi, Kazunori; Iijima, Toshie; Suzuki, Kunihiro; Kasai, Kikuo; Aso, Yoshimasa

2017-06-01

Several studies have demonstrated that both native glucagon-like peptide-1 (GLP-1) and GLP-1 receptor agonists suppress the progression of atherosclerosis in animal models. We investigated whether liraglutide, a GLP-1 analogue, could prevent the development of atherosclerosis in apolipoprotein E knockout mice (ApoE -/- ) on a high-fat diet. We also examined the influence of liraglutide on angiotensin II-induced proliferation of rat vascular smooth muscle cells (VSMCs) via enhancement of AMP-activated protein kinase (AMPK) signaling and regulation of cell cycle progression. Treatment of ApoE -/- mice with liraglutide (400 μg/day for 4 weeks) suppressed atherosclerotic lesions and increased AMPK phosphorylation in the aortic wall. Liraglutide also improved the endothelial function of thoracic aortas harvested from ApoE -/- mice in an ex vivo study. Furthermore, liraglutide increased AMPK phosphorylation in rat VSMCs, while liraglutide-induced activation of AMPK was abolished by exendin 9-39, a GLP-1 antagonist. Moreover, angiotensin (Ang) II-induced proliferation of VSMCs was suppressed by liraglutide in a dose-dependent manner, and flow cytometry of Ang II-stimulated VSMCs showed that liraglutide reduced the percentage of cells in G2/M phase (by arrest in G0/G1 phase). These findings suggest that liraglutide may inhibit Ang II-induced VSMC proliferation by activating AMPK signaling and inducing cell cycle arrest, thus delaying the progression of atherosclerosis independently of its glucose-lowering effect. Copyright © 2017 Elsevier B.V. All rights reserved.

Nicotine blocks apomorphine-induced disruption of prepulse inhibition of the acoustic startle in rats: possible involvement of central nicotinic α7 receptors

PubMed Central

Suemaru, Katsuya; Yasuda, Kayo; Umeda, Kenta; Araki, Hiroaki; Shibata, Kazuhiko; Choshi, Tominari; Hibino, Satoshi; Gomita, Yutaka

2004-01-01

Nicotine has been reported to normalize deficits in auditory sensory gating in the cases of schizophrenia, suggesting an involvement of nicotinic acetylcholine receptors in attentional abnormalities. However, the mechanism remains unclear. The present study investigated the effects of nicotine on the disruption of prepulse inhibition (PPI) of the acoustic startle response induced by apomorphine or phencyclidine in rats. Over the dose range tested, nicotine (0.05–1 mg kg−1, s.c.) did not disrupt PPI. Neither methyllycaconitine (0.5–5 mg kg−1, s.c.), an α7 nicotinic receptor antagonist, nor dihydro-β-erythroidine (0.5–2 mg kg−1, s.c.), an α4β2 nicotinic receptor antagonist, had any effect on PPI. Nicotine (0.01–0.2 mg kg−1, s.c.) dose-dependently reversed the disruption of PPI induced by apomorphine (1 mg kg−1, s.c.), but had no effect on the disruption of PPI induced by phencyclidine (2 mg kg−1, s.c.). The reversal of apomorphine-induced PPI disruption by nicotine (0.2 mg kg−1) was eliminated by mecamylamine (1 mg kg−1, i.p.), but not by hexamethonium (10 mg kg−1, i.p.), indicating the involvement of central nicotinic receptors. The antagonistic action of nicotine on apomorphine-induced PPI disruption was dose-dependently blocked by methyllycaconitine (1 and 2 mg kg−1, s.c.). However, dihydro-β-erythroidine (1 and 2 mg kg−1, s.c.) had no effect. These results suggest that nicotine reverses the disruption of apomorphine-induced PPI through central α7 nicotinic receptors. PMID:15197106

Dissociable effects of the d- and l- enantiomers of govadine on the disruption of prepulse inhibition by MK-801 and apomorphine in male Long-Evans rats.

PubMed

Lins, Brittney R; Marks, Wendie N; Phillips, Anthony G; Howland, John G

2017-04-01

The search for novel antipsychotic drugs to treat schizophrenia is driven by the poor treatment efficacy, serious side effects, and poor patient compliance of current medications. Recently, a class of compounds known as tetrahydroprotoberberines, which includes the compound d,l -govadine, have shown promise in preclinical rodent tests relevant to schizophrenia. To date, the effect of govadine on prepulse inhibition (PPI), a test for sensorimotor gating commonly used to assess the effects of putative treatments for schizophrenia, has not been determined. The objective of the present study was to determine the effects of each enantiomer of govadine ( d - and l -govadine) on PPI alone and its disruption by the distinct pharmacological compounds apomorphine and MK-801. Male Long-Evans rats were treated systemically with d - or l -govadine and apomorphine or MK-801 prior to PPI. The PPI paradigm employed here included parametric manipulations of the prepulse intensity and the interval between the prepulse and pulse. Acute MK-801 (0.15 mg/kg) significantly increased the startle response to startle pulses alone, while both MK-801 and apomorphine (0.2 mg/kg) significantly increased reactivity to prepulse-alone trials. Both MK-801 and apomorphine disrupted PPI. In addition, d -govadine alone significantly disrupted PPI in the apomorphine experiment. Pretreatment with l -, but not d -, govadine (1.0 mg/kg) blocked the effect of apomorphine and MK-801 on PPI. Treatment of rats with l -govadine alone (0.3, 1.0, 3.0 mg/kg) also dose-dependently increased PPI. Given the high affinity of l -govadine for dopamine D2 receptors, these results suggest that further testing of l -govadine as an antipsychotic is warranted.

Dopaminergic agonists that result in ocular growth inhibition also elicit transient increases in choroidal thickness in chicks

PubMed Central

Nickla, Debora L.; Totonelly, Kristen; Dhillon, Balprit

2010-01-01

The dopaminergic system has been implicated in ocular growth regulation in chicks and monkeys. In both, dopamine D2 agonists inhibit the development of myopia in response to form deprivation, and in chicks, to negative lenses as well. Because there is mounting evidence that the choroidal response to defocus plays a role in ocular growth regulation, we asked whether the effective agonists also elicit transient thickening of the choroid concomitant with the growth inhibition. Negative lenses mounted on velcro rings were worn on one eye starting at age 8-12 days. Intravitreal injections (20 μl; dose=10 nmole) of the agonist (dissolved in saline) or saline, were given through the superior temporal sclera using a 30G needle. Eyes were injected daily at noon, for 4 days, and the lenses immediately replaced. Agonists used were apomorphine (non-specific; n=17), quinpirole (D2; n=10), SKF-38393 (D1; n=9), and saline controls (n=22). For the antagonists, the same protocol was used, but on each day, the lenses were removed for 2 hours. Immediately prior to lens-removal, the antagonist was injected (20 μl; dose=5 nmole). Antagonists used were methylergonovine (non-specific; n=12), spiperone (D2; n=20), SCH-23390 (D1 n=6) and saline controls (n=27). Comparisons to saline (continuous lens wear) controls were from the agonist experiment. Axial dimensions were measured using high frequency A-scan ultrasonography at the start of lens wear, and on day 4 prior to the injections, and then again 3 hours later. Refractive errors were measured using a Hartinger's refractometer at the end of the experiment. Apomorphine and quinpirole inhibited the refractive response to the hyperopic defocus induced by the negative lenses (drug vs saline controls: -1.3 and 1.2 D vs -5.6 D; p<0.005 for both). This effect was axial: both drugs prevented the excessive ocular elongation (change in axial length: 233 and 205 μm vs 417 um; p<0.01 for both). Both drugs were also associated with a transient

Antiemetic effects of a potent and selective neurokinin-1 receptor antagonist, FK886, on cisplatin- and apomorphine-induced emesis in dogs.

PubMed

Furukawa, Takako Yoshino; Nakayama, Hiroe; Kikuchi, Aya; Imazumi, Katsunori; Yamakuni, Hisashi; Sogabe, Hajime; Yamasaki, Sachiko; Takeshita, Koji; Matsuo, Masahiko; Manda, Toshitaka; Uchida, Wataru

2013-01-01

The antiemetic properties of a novel neurokinin-1 (NK1) receptor antagonist, FK886 ([3,5-bis(trifluoromethyl)phenyl][(2R)-2-(3-hydroxy-4-methylbenzyl)-4-{2-[(2S)-2-(methoxymethyl)morpholin-4-yl]ethyl}piperazin-1-yl]methanone dihydrochloride), were studied in dog models of cisplatin- and apomorphine-induced emesis. Intravenously administered FK886 (0.32-1 mg/kg) significantly inhibited cisplatin-induced acute emesis during the 5-h observation period. Nearly complete inhibition was observed at 1 mg/kg. At an equivalent dose range, orally administered FK886 also significantly inhibited emesis, indicating good oral absorption. Similarly, FK886 inhibited apomorphine-induced emetic responses effectively following both intravenous and oral administration. The effects were long lasting, with 1.6 mg/kg of FK886 completely blocking apomorphine-induced retching and vomiting after a 12-h pretreatment period. Furthermore, FK886 showed rapid onset of antiemetic activity after oral administration. At doses of 0.32 mg/kg or more, a pretreatment time of 0.5 h was sufficient for complete inhibition of apomorphine-induced emetic responses. This fast onset after oral administration was supported by pharmacokinetic data, which demonstrated plasma levels of FK886 after oral administration reached levels similar to those 30 min after intravenous administration. These results suggest that FK886 has excellent antiemetic properties in dogs, and that its rapid-onset and long-lasting properties might make it a promising antiemetic agent.

[Rapid and prolonged facilitation of stereotyped motor behavior (verticalization) induced by apomorphine in mice previously submitted to stimulation of dopaminergic receptors].

PubMed

Costentin, J; Marçais, H; Protais, P; Schwartz, J C

1976-03-01

The climbing behaviour, a stereotyped motor behaviour, is elicited in mice by stimulation of striatal dopamine receptor by low doses of apomorphine. The action of apomorphine is unexpectedly enhanced in animals pretreated with a single dose of this agent (5 mg/kg). This enhancement occurs as early as 2 h following the first administration and persists for at least 3 days. It is also observed after pretreatments with a combination of L-DOPA and dexamphetamine. This effect seems independent from the desensitization of the dopaminergic receptors involved in thermoregulation that we have previously reported.

An ionotropic but not a metabotropic glutamate agonist potentiates the pharmacological effects of olanzapine in the rat.

PubMed

Dall'Olio, Rossella; Rimondini, Roberto; Locchi, Federica; Voltattorni, Manuela; Gandolfi, Ottavio

2005-12-01

This study aimed to evaluate the possible potentiating action of ionotropic or metabotropic (metabotropic glutamate receptor type 5) glutamate agonists on pharmacological effects induced in rats by the atypical antipsychotic olanzapine. The administration of doses of olanzapine, which did not affect spontaneous motility, inhibited behaviors induced by the selective stimulation of 5HT(2A) and D(2) receptors. In particular, 0.03 or 0.06 mg/kg of olanzapine was sufficient to reduce, respectively, head shakes induced by the 5HT(2A) agonist 1-2,5-dimethoxy-4-iodophenyl-2-aminopropane (1 mg/kg) or hypermotility elicited by the D(2) stimulant quinpirole (0.15 mg/kg). Behavioral responses to a D(1)/D(2) agonist (apomorphine-induced stereotypies) were inhibited by doses of olanzapine that also influenced spontaneous behavior. The concomitant administration of D-cycloserine, an agonist at the glycine site on the N-methyl-D-aspartate receptor complex, given at a dose (3 mg/kg) that did not affect behavior, increased the inhibitory effect of olanzapine on the responses produced by 5HT2A, D(2) and D(1)/D(2) receptor stimulation. The concomitant administration of 2-chloro-5-hydroxyphenylglycine, an agonist of metabotropic glutamate receptor type 5, increased the inhibitory effect of olanzapine on the behaviors induced by the stimulation of D(2), but not 5HT2A or D(1)/D(2) receptors. As the effect on the serotonergic system seems important for the unusual pharmacological profile of atypical antipsychotics, the present results suggest that N-methyl-D-aspartate, but not metabotropic glutamate receptor type 5 agonists could be seen as promising therapeutic agents for increasing the pharmacological effects of olanzapine.

Identification and in Vivo Evaluation of Liver X Receptor β-Selective Agonists for the Potential Treatment of Alzheimer’s Disease

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

Stachel, Shawn J.; Zerbinatti, Celina; Rudd, Michael T.

2016-04-14

Herein, we describe the development of a functionally selective liver X receptor β (LXRβ) agonist series optimized for Emax selectivity, solubility, and physical properties to allow efficacy and safety studies in vivo. Compound 9 showed central pharmacodynamic effects in rodent models, evidenced by statistically significant increases in apolipoprotein E (apoE) and ATP-binding cassette transporter levels in the brain, along with a greatly improved peripheral lipid safety profile when compared to those of full dual agonists. These findings were replicated by subchronic dosing studies in non-human primates, where cerebrospinal fluid levels of apoE and amyloid-β peptides were increased concomitantly with anmore » improved peripheral lipid profile relative to that of nonselective compounds. These results suggest that optimization of LXR agonists for Emax selectivity may have the potential to circumvent the adverse lipid-related effects of hepatic LXR activity.« less

Activation of Adiponectin Receptor Regulates Proprotein Convertase Subtilisin/Kexin Type 9 Expression and Inhibits Lesions in ApoE-Deficient Mice.

PubMed

Sun, Lei; Yang, Xiaoxiao; Li, Qi; Zeng, Peng; Liu, Ying; Liu, Lipei; Chen, Yuanli; Yu, Miao; Ma, Chuanrui; Li, Xiaoju; Li, Yan; Zhang, Rongxin; Zhu, Yan; Miao, Qing Robert; Han, Jihong; Duan, Yajun

2017-07-01

The reduced adiponectin levels are associated with atherosclerosis. Adiponectin exerts its functions by activating adiponectin receptor (AdipoR). Proprotein convertase subtilisin kexin type 9 (PCSK9) degrades LDLR protein (low-density lipoprotein receptor) to increase serum LDL-cholesterol levels. PCSK9 expression can be regulated by PPARγ (peroxisome proliferator-activated receptor γ) or SREBP2 (sterol regulatory element-binding protein 2). The effects of AdipoR agonists on PCSK9 and LDLR expression, serum lipid profiles, and atherosclerosis remain unknown. At cellular levels, AdipoR agonists (ADP355 and AdipoRon) induced PCSK9 transcription/expression that solely depended on activation of PPAR-responsive element in the PCSK9 promoter. AdipoR agonists induced PPARγ expression; thus, the AdipoR agonist-activated PCSK9 expression/production was impaired in PPARγ deficient hepatocytes. Meanwhile, AdipoR agonists transcriptionally activated LDLR expression by activating SRE in the LDLR promoter. Moreover, AMP-activated protein kinase α (AMPKα) was involved in AdipoR agonist-activated PCSK9 expression. In wild-type mice, ADP355 increased PCSK9 and LDLR expression and serum PCSK9 levels, which was associated with activation of PPARγ, AMPKα and SREBP2 and reduction of LDL-cholesterol levels. In contrast, ADP355 reduced PCSK9 expression/secretion in apoE-deficient (apoE -/- ) mice, but it still activated hepatic LDLR, PPARγ, AMPKα, and SREBP2. More importantly, ADP355 inhibited lesions in en face aortas and sinus lesions in aortic root in apoE -/- mice with amelioration of lipid profiles. Our study demonstrates that AdipoR activation by agonists regulated PCSK9 expression differently in wild-type and apoE -/- mice. However, ADP355 activated hepatic LDLR expression and ameliorated lipid metabolism in both types of mice and inhibited atherosclerosis in apoE -/- mice. © 2017 American Heart Association, Inc.

Circadian-dependent effect of melatonin on dopaminergic D2 antagonist-induced hypokinesia and agonist-induced stereotypies in rats.

PubMed

Sumaya, I C; Byers, D M; Irwin, L N; Del Val, S; Moss, D E

2004-08-01

Although a melatonin/dopamine relationship has been well established in nonmotor systems wherein dopamine and melatonin share an antagonist relationship, less clear is the role melatonin may play in extrapyramidal dopaminergic function. Therefore, the purpose of the present experiments was to examine the relationship between melatonin and the dopaminergic D2 receptor system and behavior. Hypokinesia was induced in male Sprague-Dawley rats with fluphenazine (D2 antagonist, 0.4 mg/kg ip) and stereotypies with apomorphine (D2 agonist, 0.6 mg/kg sc) during the light (1200 h) and dark (2200 h) phases. As expected, fluphenazine induced severe hypokinesia during the light phase (482 +/- 176 s); however, unexpectedly, fluphenazine-induced hypokinesia during the dark was almost nonexistent (25 +/- 6 s). Furthermore, melatonin treatment (30 mg/kg ip) produced a strong interaction with fluphenazine in that it reduced fluphenazine-induced hypokinesia by nearly 80% in the light (112 +/- 45 s) but paradoxically increased the minimal fluphenazine-induced hypokinesia in the dark by more than 60% (70 +/- 17 s). Melatonin also reduced apomorphine-induced stereotypies by nearly 40% in the light but had no effect in the dark. Taken together, these data show (1) a strong and unexpected nocturnal effect of fluphenazine on hypokinesia and (2) provide support for an antagonistic melatonin/dopaminergic interaction in the context of motor behavior and D2 receptor function which appears to be critically dependent on the light/dark status of the dopaminergic system. Copyright 2004 Elsevier Inc.

Treatment of Parkinson's disease could be regulated by movement sensors: subcutaneous infusion of varying apomorphine doses according to the intensity of motor activity.

PubMed

Rodríguez-Molinero, Alejandro; Pérez-Martínez, David A; Català, Andreu; Cabestany, Joan; Yuste, Antonio

2009-04-01

Most recent therapeutic solutions to treat Parkinson's disease seek continuous administration of dopaminergic agonists, as for example rigotine patches or apomorphine infusion pumps. Such drug-delivery devices are aimed at preventing fluctuations in drug plasma levels, which could cause certain symptoms such as wearing-off periods or dyskinesia. However, we postulate that drug plasma levels should not keep constant, but rather adjust to the varying intensity of the different user's activities. The rationale behind this is that the drug amount appropriate to treat a patient at rest is lower than that required to treat the same patient when engaged in physical activity. We propose dynamic real-time dose adjustment, so that the doses increase as the patient starts performing physical activity, thus preventing off periods such as "freeze" phenomenon, and the doses reduce during the resting periods, thus preventing adverse effects. Small portable movement sensors are currently available, which detect the amount and type of activity in a continuous way. Combining such technology with infusion pumps to produce modified pumps capable of adjusting the infusion rate to the user's activity, seems to be feasible in the short-term.

D-1 and D-2 receptor blockade have additive cataleptic effects in mice, but receptor effects may interact in opposite ways.

PubMed

Klemm, W R; Block, H

1988-02-01

The dopaminergic role of D-1 and D-2 receptors in catalepsy was evaluated using drugs with preferential receptor affinities. The D-1 antagonist, SCH 23390, caused distinct catalepsy in mice at 1, 2, and 10 mg/kg, IP, but not at two lower doses. The selective D-1 blocker, molindone, also caused catalepsy at 5 and 10 mg/kg; and blockade of both receptor types produced additive cataleptogenic effects. Apomorphine (4 mg/kg), which is an agonist for both receptors, potentiated SCH 23390-induced catalepsy much more than it did the catalepsy induced by molindone; the potentiation was produced by higher, not lower, doses of apomorphine. To determine if the apomorphine potentiation was mediated by D-1 or D-2 receptors, we tested selective agonists in mice that were concurrently injected with selective blockers. SCH 23390-induced catalepsy was potentiated by a large dose of the D-2 agonist, bromocriptine. The catalepsy of D-2 blockade with molindone was not potentiated by the D-1 agonist, SKF 38393, which slightly disrupted the catalepsy of D-2 blockade. We conclude that catalepsy is not a simple D-2 blockade phenomenon and that preferential antagonism of either receptor type can cause catalepsy. Catalepsy is most profound when both receptor types are blocked. Dopamine agonists, in large concentrations, are known to promote movements, and thus it is not surprising that they tend to disrupt catalepsy.(ABSTRACT TRUNCATED AT 250 WORDS)

High but not low ECS stimulus intensity augments apomorphine-stimulated dopamine postsynaptic receptor functioning in rats.

PubMed

Andrade, Chittaranjan; Srinivasamurthy, Gurunath M; Vishwasenani, A; Prakash, G Sai; Srihari, B S; Chandra, J Suresh

2002-06-01

Clinical research shows that the antidepressant and cognitive adverse effects of electroconvulsive therapy are both dependent on the administered electrical stimulus intensity (dose); however, dose-dependent neurotransmitter system changes in the brain, which might underlie the therapeutic or adverse effects, remain to be demonstrated. We used a behavioral model to examine dose-related effects of electroconvulsive shock (ECS) on dopamine postsynaptic receptor functioning in the rat brain. In a factorially designed study, rats (n = 100) were treated with five once-daily ECSs at three levels (sham ECS, 30 mC ECS, and 120 mC ECS), and with drug at two levels (saline, and 1 mg/kg s.c. apomorphine). Motility was assessed in the small open field. Apomorphine-elicited, dopamine postsynaptic receptor-mediated hypermotility was significantly increased by 120 mC ECS but not by 30 mC ECS. An additional but unrelated finding was that, while the ECS seizure duration expectedly decreased across time, no dose-dependent effects were observed. ECS-induced dopamine postsynaptic receptor up-regulation may depend on the intensity of the administered electrical stimulus.

Basal ganglia and gait control: apomorphine administration and internal pallidum stimulation in Parkinson's disease.

PubMed

Grasso, R; Peppe, A; Stratta, F; Angelini, D; Zago, M; Stanzione, P; Lacquaniti, F

1999-05-01

Gait coordination was analyzed (four-camera 100 Hz ELITE system) in two groups of idiopathic Parkinson disease (PD) patients. Five patients underwent continuous infusion of apomorphine and were recorded in two different sessions (APO OFF and APO ON) in the same day. Three patients with a previous chronic electrode implantation in both internal globi pallidi (GPi) were recorded in the same experimental session with the electrodes on and off (STIM ON and STIM OFF). The orientation of both the trunk and the lower-limb segments was described with respect to the vertical in the sagittal plane. Lower-limb inter-segmental coordination was evaluated by analyzing the co-variation between thigh, shank, and foot elevation angles by means of orthogonal planar regression. At least 30 gait cycles per experimental condition were processed. We found that the trunk was bent forward in STIM OFF, whereas it was better aligned with the vertical in STIM ON in both PD groups. The legs never fully extended during the gait cycle in STIM OFF, whereas they extended before heel strike in STIM ON. The multisegmental coordination of the lower limb changed almost in parallel with the changes in trunk orientation. In STIM OFF, both the shape and the spatial orientation of the planar gait loops (thigh angle vs. shank angle vs. foot angle) differed from those of physiological locomotion, whereas in STIM ON the gait loop tended to resume features closer to the control. Switching the electrodes on and off in patients with GPi electrodes resulted in quasi-parallel changes of the trunk inclination and of the planar gait loop. The bulk of the data suggest that the basal-ganglia circuitry may be relevant in locomotion by providing an appropriate spatio-temporal framework for the control of posture and movement in a gravity-based body-centered frame of reference. Pallido-thalamic and/or pallido-mesencephalic pathways may influence the timing of the inter-segmental coordination for gait.

Agonist-induced glycogenolysis in rabbit retinal slices and cultures.

PubMed Central

Ghazi, H.; Osborne, N. N.

1989-01-01

1. The effects of different putative retinal transmitters and/or modulators on glycogenolysis in rabbit retinal slices and in retinal Müller cell cultures were examined. 2. Incubation of rabbit retinal slices or primary retinal cultures (either 3-5 day-old or 25-30 day-old) in a buffer solution containing [3H]-glucose resulted in the accumulation of newly synthesized [3H]-glycogen. 3. Noradrenaline (NA), isoprenaline, vasoactive intestinal peptide (VIP), 5-hydroxytryptamine (5-HT) and 8-hydroxy-dipropylaminetetralin (8-OH-DPAT) stimulated the hydrolysis of this newly formed 3H-polymer. The potency order of maximal stimulations was: VIP greater than NA greater than isoprenaline greater than 5-HT greater than 8-OH-DPAT. 4. The putative retinal transmitters, dopamine, gamma-aminobutyric acid (GABA), glycine and taurine and the muscarinic agonist carbachol (CCh) had no effect on [3H]-glycogen content. 5. The glycogenolytic effects of NA/isoprenaline and 5-HT/8-OH-DPAT appear to be mediated by beta-adrenoceptors and 5-HT1 receptors (possibly 5-HT1A), respectively while the VIP-induced response involved another receptor subtype. 6. Agonists which mediated [3H]-glycogen hydrolysis also stimulated an increase in adenosine 3':5'-cyclic monophosphate (cyclic AMP) formation. Both responses are blocked to a similar extent by the same antagonists and so are probably mediated via the same receptor subtypes. Moreover, dibutyryl cyclic AMP (db cyclic AMP) promoted tritiated glycogen breakdown in the three retinal preparations. 7. Not all receptors linked to cyclic AMP production however promote glycogenolysis. Dopamine and apomorphine stimulated cyclic AMP formation via D1-receptors without influencing glycogenolysis. These receptors are exclusively associated with neurones. PMID:2568145

Dopaminergic agonists that result in ocular growth inhibition also elicit transient increases in choroidal thickness in chicks.

PubMed

Nickla, Debora L; Totonelly, Kristen; Dhillon, Balprit

2010-11-01

The dopaminergic system has been implicated in ocular growth regulation in chicks and monkeys. In both, dopamine D2 agonists inhibit the development of myopia in response to form deprivation, and in chicks, to negative lenses as well. Because there is mounting evidence that the choroidal response to defocus plays a role in ocular growth regulation, we asked whether the effective agonists also elicit transient thickening of the choroid concomitant with the growth inhibition. Negative lenses mounted on velcro rings were worn on one eye starting at age 8-12 days. Intravitreal injections (20 μl; dose = 10 nmole) of the agonist (dissolved in saline) or saline, were given through the superior temporal sclera using a 30G needle. Eyes were injected daily at noon, for 4 days, and the lenses immediately replaced. Agonists used were apomorphine (non-specific; n = 17), quinpirole (D2; n = 10), SKF-38393 (D1; n = 9), and saline controls (n = 22). For the antagonists, the same protocol was used, but on each day, the lenses were removed for 2 h. Immediately prior to lens-removal, the antagonist was injected (20 μl; dose = 5 nmole). Antagonists used were methylergonovine (non-specific; n = 12), spiperone (D2; n = 20), SCH-23390 (D1; n = 6) and saline controls (n = 27). Comparisons to saline (continuous lens wear) controls were from the agonist experiment. Axial dimensions were measured using high frequency A-scan ultrasonography at the start of lens wear, and on day 4 prior to the injections, and then again 3 h later. Refractive errors were measured using a Hartinger's refractometer at the end of the experiment. Apomorphine and quinpirole inhibited the refractive response to the hyperopic defocus induced by the negative lenses (drug vs saline controls: -1.3 and 1.2 D vs -5.6 D; p < 0.005 for both). This effect was axial: both drugs prevented the excessive ocular elongation (change in axial length: 233 and 205 μm vs 417 μm; p < 0.01 for both

High-performance liquid chromatographic separation and electrochemical or spectrophotometric determination of R(-)N-n-propylnorapomorphine and R(-)10,11-methylenedioxy-N-n-propylnoraporphine in primate plasma.

PubMed

Lampen, P; Neumeyer, J L; Baldessarini, R J

1988-04-29

The dopamine receptor agonist R(-)N-n-propylnorapomorphine (NPA) and its proposed pro-drug R(-)10,11-methylenedioxy-N-n-propylnoraporphine (MDO-NPA) were isolated simultaneously from monkey plasma using a solid-phase extraction procedure. R(-)Apomorphine (APO) and R(-)10,11-methylenedioxyaporphine (MDO-APO) were added as internal standards, and separation and quantification were by high-performance liquid chromatography with electrochemical or ultraviolet detection of the free catechol and MDO compounds, respectively. The detection limits for NPA and MDO-NPA in plasma were 0.5 and 10 ng/ml and the coefficient of variation (S.D./mean) within assays and between days of assays for both drugs was 5.6% or less. Quantification of plasma levels of NPA and MDO-NPA was possible at ranges of 2-1000 and 40-5000 ng/ml, respectively, including concentrations found after intravenous administration of these agents.

Dopamine receptors play distinct roles in sexual behavior expression of rats with a different sexual motivational tone.

PubMed

Guadarrama-Bazante, Irma L; Canseco-Alba, Ana; Rodríguez-Manzo, Gabriela

2014-10-01

Dopamine (DA) plays a central role in the expression of male sexual behavior. The effects of DA-enhancing drugs on copulation seem to vary depending on the dose of the agonist used, the type of DA receptor activated, and the sexual condition of the animals. The aim of the present study was to carry out a systematic analysis of the effects of dopaminergic agonists on the expression of male sexual behavior by sexually competent rats in different sexual motivational states, that is when sexually active (sexually experienced) and when temporarily inhibited (sexually exhausted). To this end, the same doses of the nonselective DA receptor agonist apomorphine, the selective D2-like DA receptor agonist quinpirole, and the selective D1-like DA receptor agonist SKF38393 were injected intraperitoneally to sexually experienced or sexually exhausted male rats and their sexual behavior was recorded. Low apomorphine doses induced expression of sexual behavior in sexually satiated rats, but only reduced the intromission latency of sexually experienced rats. SKF38393 facilitated the expression of sexual behavior by sexually exhausted rats, but not that of sexually experienced males and quinpirole did not exert an effect in both types of animal. In line with these results, the apomorphine-induced reversal of sexual exhaustion was blocked by the D1-like receptor antagonist SCH23390. The data suggest that DA receptors play distinct roles in the expression of sexual behavior by male rats depending on their motivational state and that activation of D1-like receptors promotes the expression of sexual behavior in satiated rats.

Rotigotine Transdermal Patch Improves Swallowing in Dysphagic Patients with Parkinson's Disease.

PubMed

Hirano, Makito; Isono, Chiharu; Sakamoto, Hikaru; Ueno, Shuichi; Kusunoki, Susumu; Nakamura, Yusaku

2015-08-01

Abnormal swallowing, dysphagia, is a potentially fatal symptom in Parkinson's disease (PD) and is characterized by frequent silent aspiration, an unrecognized risk of suffocation and aspiration pneumonia. Several studies have reported that the injection of apomorphine, a dopamine agonist, alleviated dysphagia in some patients with PD. The effects of other antiparkinson medications against dysphagia remain controversial. Rotigotine is another dopamine agonist with non-oral administration, i.e., a transdermal patch. Its noninvasiveness seems to render this medicine even more suitable than apomorphine for dysphasic patients. However, no direct evidence has been reported. In the present retrospective open-label study, we for the first time objectively showed that rotigotine improved swallowing on videofluoroscopic examination in dysphagic patients with PD.

Prenatal ethanol enhances rotational behavior to apomorphine in the 24-month-old rat offspring with small striatal lesion.

PubMed

Gomide, Vânia C; Chadi, Gerson

2004-01-01

Pregnant Wistar rats received a hyperproteic liquid diet containing 37.5% ethanol-derived calories during gestation. Isocaloric amount of liquid diet, with maltose-dextrin substituted for ethanol, was given to control pair-fed dams. Offsprings were allowed to survive until 24 months of age. A set of aged female offsprings of both control diet and ethanol diet groups was registered for spontaneous motor activity, by means of an infrared motion sensor activity monitor, or for apomorphine-induced rotational behavior, while another lot of male offsprings was submitted to an unilateral striatal small mechanical lesion by a needle, 6 days before rotational recordings. Prenatal ethanol did not alter spontaneous motor parameters like resting time as well as the events of small and large movements in the aged offsprings. Bilateral circling behavior was already increased 5 min after apomorphine in the unlesioned offsprings of both the control and ethanol diet groups. However, it lasted more elevated for 45- to 75-min time intervals in the gestational ethanol-exposed offsprings, while decreasing faster in the control offsprings. Apomorphine triggered a strong and sustained elevation of contraversive turns in the striatal-lesioned 24-month-old offsprings of the ethanol group, but only a small and transient elevation was seen in the offsprings of the control diet group. Astroglial and microglial reactions were seen surrounding the striatal needle track lesion. Microdensitometric image analysis demonstrated no differences in the levels of tyrosine hydroxylase immunoreactivity in the striatum of 24-month-old unlesioned and lesioned offsprings of control and alcohol diet groups. The results suggest that ethanol exposure during gestation may alter the sensitivity of dopamine receptor in aged offsprings, which is augmented by even a small striatal lesion.

Mechanism of action of a peroxisome proliferator-activated receptor (PPAR)-delta agonist on lipoprotein metabolism in dyslipidemic subjects with central obesity.

PubMed

Ooi, Esther M M; Watts, Gerald F; Sprecher, Dennis L; Chan, Dick C; Barrett, P Hugh R

2011-10-01

Dyslipidemia increases the risk of cardiovascular disease in obesity. Peroxisome proliferator-activated receptor (PPAR)-δ agonists decrease plasma triglycerides and increase high-density lipoprotein (HDL)-cholesterol in humans. The aim of the study was to examine the effect of GW501516, a PPAR-δ agonist, on lipoprotein metabolism. Design, Setting, and Intervention: We conducted a randomized, double-blind, crossover trial of 6-wk intervention periods with placebo or GW501516 (2.5 mg/d), with 2-wk placebo washout between treatment periods. We recruited 13 dyslipidemic men with central obesity from the general community. We measured the kinetics of very low-density lipoprotein (VLDL)-, intermediate-density lipoprotein-, and low-density lipoprotein (LDL)-apolipoprotein (apo) B-100, plasma apoC-III, and high-density lipoprotein (HDL) particles (LpA-I and LpA-I:A-II). GW501516 decreased plasma triglycerides, fatty acid, apoB-100, and apoB-48 concentrations. GW501516 decreased the concentrations of VLDL-apoB by increasing its fractional catabolism and of apoC-III by decreasing its production rate (P < 0.05). GW501516 reduced VLDL-to-LDL conversion and LDL-apoB production. GW501516 increased HDL-cholesterol, apoA-II, and LpA-I:A-II concentrations by increasing apoA-II and LpA-I:A-II production (P < 0.05). GW501516 decreased cholesteryl ester transfer protein activity, and this was paralleled by falls in the triglyceride content of VLDL, LDL, and HDL and the cholesterol content of VLDL and LDL. GW501516 increased the hepatic removal of VLDL particles, which might have resulted from decreased apoC-III concentration. GW501516 increased apoA-II production, resulting in an increased concentration of LpA-I:A-II particles. This study elucidates the mechanism of action of this PPAR-δ agonist on lipoprotein metabolism and supports its potential use in treating dyslipidemia in obesity.

Effect of AVE 0991 angiotensin-(1-7) receptor agonist treatment on elemental and biomolecular content and distribution in atherosclerotic plaques of apoE-knockout mice

NASA Astrophysics Data System (ADS)

Kowalska, J.; Gajda, M.; Jawień, J.; Kwiatek, W. M.; Appel, K.; Dumas, P.

2013-12-01

Gene-targeted apolipoprotein E-knockout (apoE-KO) mice display early and highly progressive vascular lesions containing lipid deposits and they became a reliable animal model to study atherosclerosis. The aim of the present study was to investigate the effect of AVE 0991 angiotensin-(1-7) receptor agonist on the distribution of selected pro- and anti- inflammatory elements as well as biomolecules in atherosclerotic plaques of apoE-knockout mice. Synchrotron radiation-based X-ray fluorescence (micro-XRF) and Fourier Transform Infrared (micro-FTIR) microspectroscopies were applied. Two-month-old apoE-KO mice were fed for following four months diet supplemented with AVE 0991 (0.58 μmol/kg b.w. per day). Histological sections of ascending aortas were analyzed spectroscopically. The distribution of P, Ca, Fe and Zn were found to correspond with histological structure of the lesion. Significantly lower contents of P, Ca, Zn and significantly higher content of Fe were observed in animals treated with AVE 0991. Biomolecular analysis showed lower lipids saturation level and lower lipid to protein ratio in AVE 0991 treated group. Protein secondary structure was studied according to the composition of amide I band (1660 cm-1) and it demonstrated higher proportion of β-sheet structure as compared to α-helix in both studied groups.

Hyperactivity induced by stimulation of separate dopamine D-1 and D-2 receptors in rats with bilateral 6-OHDA lesions.

PubMed

Arnt, J

1985-08-26

The effects of DA agonists and antagonists with different dopamine (DA) D-1 and D-2 receptor selectivity have been studied in rats with bilateral 6-OHDA lesions. The D-1 agonist SK & F 38393, the D-2 agonist pergolide and the mixed agonist apomorphine all induced marked hyperactivity in lesioned rats in doses which were without stimulant effect in sham-operated animals. The hyperactivity induced by SK & F 38393 was blocked by the DA D-1 antagonist SCH 23390, but unaffected by the D-2 antagonists spiroperidol or clebopride. Pergolide-induced hyperactivity showed the reverse selectivity. The mixed D-1/D-2 antagonists, cis(Z)-flupentixol and cis(Z)-clopenthixol, however blocked the effect of both agonists. Apomorphine-induced hyperactivity was neither blocked by selective D-1 nor D-2 antagonists, but was dose-dependently inhibited by cis(Z)-flupentixol and cis(Z)-clopenthixol. Potent blockade was also obtained by combined treatment with SCH 23390 and spiroperidol, indicating the need of blocking both D-1 and D-2 receptors simultaneously. The results indicate that D-1 and D-2 receptor function can be independently manipulated in denervated rats and they confirm similar results obtained in rats with unilateral 6-OHDA lesions using circling behaviour.

Potentiation of cytotoxic chemotherapy by growth hormone-releasing hormone agonists.

PubMed

Jaszberenyi, Miklos; Rick, Ferenc G; Popovics, Petra; Block, Norman L; Zarandi, Marta; Cai, Ren-Zhi; Vidaurre, Irving; Szalontay, Luca; Jayakumar, Arumugam R; Schally, Andrew V

2014-01-14

The dismal prognosis of malignant brain tumors drives the development of new treatment modalities. In view of the multiple activities of growth hormone-releasing hormone (GHRH), we hypothesized that pretreatment with a GHRH agonist, JI-34, might increase the susceptibility of U-87 MG glioblastoma multiforme (GBM) cells to subsequent treatment with the cytotoxic drug, doxorubicin (DOX). This concept was corroborated by our findings, in vivo, showing that the combination of the GHRH agonist, JI-34, and DOX inhibited the growth of GBM tumors, transplanted into nude mice, more than DOX alone. In vitro, the pretreatment of GBM cells with JI-34 potentiated inhibitory effects of DOX on cell proliferation, diminished cell size and viability, and promoted apoptotic processes, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay, ApoLive-Glo multiplex assay, and cell volumetric assay. Proteomic studies further revealed that the pretreatment with GHRH agonist evoked differentiation decreasing the expression of the neuroectodermal stem cell antigen, nestin, and up-regulating the glial maturation marker, GFAP. The GHRH agonist also reduced the release of humoral regulators of glial growth, such as FGF basic and TGFβ. Proteomic and gene-expression (RT-PCR) studies confirmed the strong proapoptotic activity (increase in p53, decrease in v-myc and Bcl-2) and anti-invasive potential (decrease in integrin α3) of the combination of GHRH agonist and DOX. These findings indicate that the GHRH agonists can potentiate the anticancer activity of the traditional chemotherapeutic drug, DOX, by multiple mechanisms including the induction of differentiation of cancer cells.

Opposing Effects of Dopamine D1- and D2-Like Agonists on Intracranial Self-Stimulation in Male Rats

PubMed Central

Lazenka, Matthew F.; Legakis, Luke P.; Negus, S. Stevens

2016-01-01

Dopamine acts through dopamine type 1 receptors (comprised of D1 and D5 subtypes) and dopamine type 2 receptors (comprised of D2, D3 and D4 subtypes). Intracranial self-stimulation (ICSS) is one experimental procedure that can be used to evaluate abuse-related effects of drugs targeting dopamine receptors. This study evaluated effects of dopamine receptor ligands on ICSS in rats using experimental procedures that have been used previously to examine abused indirect dopamine agonists such as cocaine and amphetamine. Male Sprague-Dawley rats responded under a fixed-ratio 1 schedule for electrical stimulation of the medial forebrain bundle, and frequency of stimulation varied from 56–158 Hz in 0.05 log increments during each experimental session. Drug potency and time course were determined for the D1 ligands A77636, SKF82958, SKF38393, fenoldopam and SCH39166 and the D2/3 ligands sumanirole, apomorphine, quinpirole, PD128907, pramipexole, aripiprazole, eticolopride and PG01037. The high-efficacy D1 agonists A77636 and SKF82958 produced dose-dependent, time-dependent, and abuse-related facilitation of ICSS. Lower efficacy D1 ligands and all D2/3 ligands failed to facilitate ICSS at any dose or pretreatment time. A mixture of SKF82958 and quinpirole produced a mixture of effects produced by each drug alone. Quinpirole also failed to facilitate ICSS after regimens of repeated treatment with either quinpirole or cocaine. These studies provide more evidence for divergent effects of dopamine D1- and D2-family agonists on ICSS procedure in rats and suggest that ICSS may be a useful complement to other approaches for preclinical abuse potential assessment, in part because of the reproducibility of results. PMID:26987070

Long-term adherence to apomorphine infusion in patients with Parkinson disease: a 10-year observational study.

PubMed

Kimber, Thomas E; Fang, Jing; Huddy, Lynda J; Thompson, Philip D

2017-05-01

Patients with Parkinson disease (PD) commonly experience motor fluctuations and dyskinesias in response to oral dopaminergic medications. Affected patients may benefit from device-assisted therapy, such as medication infusion or deep brain stimulation surgery. This is the first Australian study of the long-term adherence to apomorphine infusion (AI) in patients with PD. To assess the adherence to AI in patients with PD in a single centre over a 10-year period and to find the reasons for discontinuation in patients who discontinued AI. This is an observational study of patients with PD treated with AI between 2004 and 2014. Outcome measures included changes in motor function and quality of life following AI, change in dose of other dopaminergic medications following AI, duration of infusion, adverse effects, reasons for cessation of AI and subsequent treatment after cessation. Mean duration of AI was 21.65 months. No patient achieved apomorphine monotherapy, and the mean reduction in the levodopa-equivalent dose of other dopaminergic medications after AI was 22.7%. The benefit of AI on motor function and quality of life was rated as 'much improved' or 'better' in 83% of patients. The most common reasons for discontinuation of AI were adverse effects and inadequate motor benefit. Most patients who discontinued AI were subsequently treated with another device-assisted therapy. AI is an effective therapy for severe motor response complications in PD, especially in the short and medium term. However, many patients cannot be maintained on AI in the longer term. © 2017 Royal Australasian College of Physicians.

Post-trial dopaminergic modulation of conditioned catalepsy: A single apomorphine induced increase/decrease in dopaminergic activation immediately following a conditioned catalepsy response can reverse/enhance a haloperidol conditioned and sensitized catalepsy response.

PubMed

Oliveira, Lucas Rangel; Dias, Flávia Regina Cruz; Santos, Breno Garone; Silva, Jade Leal Loureiro; Carey, Robert J; Carrera, Marinete Pinheiro

2016-09-15

Haloperidol can induce catalepsy and this drug effect can be conditioned as well as sensitized to contextual cues. We used a paired/unpaired Pavlovian conditioning protocol to establish haloperidol catalepsy conditioned and sensitized responses. Groups of rats were given 10 daily catalepsy tests following administration of vehicle (n=24) or haloperidol (1.0mg/kg) either paired (n=18) or unpaired (n=18) to testing. Subsequently, testing for conditioning was conducted and conditioning and sensitization of catalepsy were observed selectively in the paired group. Immediately following a second test for catalepsy conditioning, the groups were subdivided into 4 vehicle groups, 3 unpaired haloperidol groups and 3 paired haloperidol groups and were given one of three post-trial treatments (vehicle, 0.05mg/kg or 2.0mg/kg apomorphine). One day later the conditioned catalepsy test 3 was carried out and on the next day, a haloperidol challenge test was performed. The post-trial apomorphine treatments had major effects on the paired groups upon both conditioning and the haloperidol challenge test. The low dose apomorphine post-trial treatment enhanced both the conditioned and the haloperidol sensitized catalepsy responses. The high dose apomorphine post-trial treatment eliminated conditioned catalepsy and eliminated the initial acute catalepsy response to haloperidol that was induced in the vehicle control groups. These results demonstrate the sensitivity of conditioned drug cues to modification by increases/decreases in activity of the dopamine system in the immediate post-trial interval after a conditioning trial. This demonstration that post-trial dopaminergic drug treatments can modify conditioned drug behavior has broad implications for conditioned drug effects. Copyright © 2016 Elsevier B.V. All rights reserved.

Agonist-induced modulation of inverse agonist efficacy at the beta 2-adrenergic receptor.

PubMed

Chidiac, P; Nouet, S; Bouvier, M

1996-09-01

Sustained stimulation of several G protein-coupled receptors is known to lead to a reduction in the signaling efficacy. This phenomenon, named agonist-induced desensitization, has been best studied for the beta 2-adrenergic receptor (AR) and is characterized by a decreased efficacy of beta-adrenergic agonists to stimulate the adenylyl cyclase activity. Recently, several beta-adrenergic ligands were found to inhibit the spontaneous agonist-independent activity of the beta 2AR. These compounds, termed inverse agonists, have different inhibitory efficacies, ranging from almost neutral antagonists to full inverse agonists. The current study was undertaken to determine whether, as is the case for agonists, desensitization can affect the efficacies of inverse agonists. Agonist-promoted desensitization of the human beta 2AR expressed in Sf9 cells potentiated the inhibitory actions of the inverse agonists, with the extent of the potentiation being inversely proportional to their intrinsic activity. For example, desensitization increased the inhibitory action of the weak inverse agonist labetalol by 29%, whereas inhibition of the spontaneous activity by the strong inverse agonist timolol was not enhanced by the desensitizing stimuli. Interestingly, dichloroisoproterenol acted stochastically as either a weak partial agonist or a weak inverse agonist in control conditions but always behaved as an inverse agonist after desensitization. These data demonstrate that like for agonists, the efficacies of inverse agonists can be modulated by a desensitizing treatment. Also, the data show that the initial state of the receptor can determine whether a ligand behaves as a partial agonist or an inverse agonist.

β2 Agonists.

PubMed

Billington, Charlotte K; Penn, Raymond B; Hall, Ian P

2017-01-01

History suggests β agonists, the cognate ligand of the β 2 adrenoceptor, have been used as bronchodilators for around 5,000 years, and β agonists remain today the frontline treatment for asthma and chronic obstructive pulmonary disease (COPD). The β agonists used clinically today are the products of significant expenditure and over 100 year's intensive research aimed at minimizing side effects and enhancing therapeutic usefulness. The respiratory physician now has a therapeutic toolbox of long acting β agonists to prophylactically manage bronchoconstriction, and short acting β agonists to relieve acute exacerbations. Despite constituting the cornerstone of asthma and COPD therapy, these drugs are not perfect; significant safety issues have led to a black box warning advising that long acting β agonists should not be used alone in patients with asthma. In addition there are a significant proportion of patients whose asthma remains uncontrolled. In this chapter we discuss the evolution of β agonist use and how the understanding of β agonist actions on their principal target tissue, airway smooth muscle, has led to greater understanding of how these drugs can be further modified and improved in the future. Research into the genetics of the β 2 adrenoceptor will also be discussed, as will the implications of individual DNA profiles on the clinical outcomes of β agonist use (pharmacogenetics). Finally we comment on what the future may hold for the use of β agonists in respiratory disease.

Effects of amantadine on modification of dopamine dependent behaviours by molindone.

PubMed

Dhaware, B S; Balsara, J J; Nandal, N V; Chandorkar, A G

2000-08-01

Amantadine, a dopamine agonist is reported to act by releasing dopamine from the dopaminergic nerve terminals as an anti-Parkinsonian drug. In the present behavioural study in the rat, molindone-induced catalepsy and ptosis, which are dopamine dependent-behaviors are reversed by amantadine. Amantadine has also revered molindone-induced inhibition of traction response in mice. Our study indicates that amantadine, like other DA agonists, e.g. amphetamine and apomorphine can antagonize or even reverse the neuroleptic induced dopaminergic behaviors.

Dopamine activates masculine sexual behavior independent of the estrogen receptor alpha.

PubMed

Wersinger, S R; Rissman, E F

2000-06-01

Estrogen receptor alpha (ERalpha) is believed to be a critical part of the regulatory processes involved in normal reproduction and sexual behavior. However, in this study we show the ERalpha is not required for display of masculine sexual behavior. Male and female, ERalpha knock-out (ERalphaKO) and wild-type mice were gonadectomized and implanted with testosterone. Sexual behavior and social preferences were tested after injection of the dopamine agonist, apomorphine (APO), or vehicle. All wild-type mice showed normal masculine behavior, including mounts and pelvic thrusts in females, and ejaculation in males. In agreement with past reports, ERalphaKO mice, given vehicle, failed to show mating behavior. Yet, ERalphaKO males given APO showed masculine copulatory behavior and chemoinvestigatory behavior directed at females. ERalphaKO females, treated with APO, mounted and thrusted when tested with receptive females. HPLC revealed that wild-type and ERalphaKO mice had equivalent catecholamine content in brain regions associated with masculine sexual behavior. These data show that the ERalpha is not essential during development or adulthood for the expression of masculine sexual behavior in mice. Moreover, dopamine can activate sexual behavior via a mechanism that either acts on an ER other than ERalpha or via an estrogen-independent pathway.

Evidence that central dopamine receptors modulate sympathetic neuronal activity to the adrenal medulla to alter glucoregulatory mechanisms.

PubMed

Arnerić, S P; Chow, S A; Bhatnagar, R K; Webb, R L; Fischer, L J; Long, J P

1984-02-01

Previous reports suggest that analogs of dopamine (DA) can produce hyperglycemia in rats by interacting with DA receptors. Experiments reported here indicate the site of action and describe the metabolic sequalae associated with the hyperglycemic effect of apomorphine (APO), produced in conscious unrestrained rats. Apomorphine was more potent when administered by intracerebroventricular (i.c.v.) injection than when given subcutaneously (s.c.). Very small doses of the DA receptor antagonist pimozide, given intraventricularly, blocked the hyperglycemic effect of apomorphine administered subcutaneously. Sectioning of the spinal cord at thoracic vertebra T1-2 or sectioning the greater splanchnic nerve blocked apomorphine-induced hyperglycemia; whereas section of the superior colliculus or section at T5-6 had no effect. A dose of apomorphine or epinephrine (EPI) producing a similar degree of hyperglycemia elevated the concentration of EPI in serum to a similar degree, and the increase in EPI in serum preceded the increase in glucose in serum. Fasting animals for 2 or 18 hr had no significant effect on EPI- or apomorphine-induced hyperglycemia despite a reduction (91-93%) of the glycogen content of liver and skeletal muscle during the 18 hr fast. 5-Methoxyindole-2-carboxylic acid (MICA), an inhibitor of gluconeogenesis, blocked EPI- and apomorphine-induced hyperglycemia in rats fasted for 18 hr. However, 5-methoxyindole-2-carboxylic acid was ineffective in blocking hyperglycemia in animals fasted for 2 hr. Changes in insulin or glucagon in serum alone cannot account for the hyperglycemic action of apomorphine. These data demonstrate that apomorphine interacts with central DA receptors located in the hindbrain to activate sympathetic neuronal activity to the adrenal gland which subsequently releases epinephrine to alter homeostasis of glucose. Epinephrine may then, depending on the nutritional status, facilitate glycogenolytic or gluconeogenic processes to produce

The role of beta-arrestin2 in shaping fMRI BOLD responses to dopaminergic stimulation.

PubMed

Sahlholm, Kristoffer; Ielacqua, Giovanna D; Xu, Jinbin; Jones, Lynne A; Schlegel, Felix; Mach, Robert H; Rudin, Markus; Schroeter, Aileen

2017-07-01

The dopamine D 2 receptor (D 2 R) couples to inhibitory G i/o proteins and is targeted by antipsychotic and antiparkinsonian drugs. Beta-arrestin2 binds to the intracellular regions of the agonist-occupied D 2 R to terminate G protein activation and promote internalization, but also to initiate downstream signaling cascades which have been implicated in psychosis. Functional magnetic resonance imaging (fMRI) has proven valuable for measuring dopamine receptor-mediated changes in neuronal activity, and might enable beta-arrestin2 function to be studied in vivo. The present study examined fMRI blood oxygenation level dependent (BOLD) signal changes elicited by a dopamine agonist in wild-type (WT) and beta-arrestin2 knockout (KO) mice, to investigate whether genetic deletion of beta-arrestin2 prolongs or otherwise modifies D 2 R-dependent responses. fMRI BOLD data were acquired on a 9.4 T system. During scans, animals received 0.2 mg/kg apomorphine, i.v. In a subset of experiments, animals were pretreated with 2 mg/kg of the D 2 R antagonist, eticlopride. Following apomorphine administration, BOLD signal decreases were observed in caudate/putamen of WT and KO animals. The time course of response decay in caudate/putamen was significantly slower in KO vs. WT animals. In cingulate cortex, an initial BOLD signal decrease was followed by a positive response component in WT but not in KO animals. Eticlopride pretreatment significantly reduced apomorphine-induced BOLD signal changes. The prolonged striatal response decay rates in KO animals might reflect impaired D 2 R desensitization, consistent with the known function of beta-arrestin2. Furthermore, the apomorphine-induced positive response component in cingulate cortex may depend on beta-arrestin2 signaling downstream of D 2 R.

Effects of dopaminergic agents on progression of naturally occurring myopia in albino guinea pigs (Cavia porcellus).

PubMed

Jiang, Liqin; Long, Keli; Schaeffel, Frank; Zhou, Xiangtian; Zheng, Yibo; Ying, Huangfang; Lu, Fan; Stell, William K; Qu, Jia

2014-09-30

Disruption of dopaminergic signaling has been implicated in the abnormalities of ocular development in albinism, and many experiments have shown that retinal dopamine is a major regulator of postnatal eye growth and myopia in animal models. Therefore, in the present study we investigated whether progressive myopia, which can occur in albino guinea pigs without experimental manipulation of visual conditions, is affected by dopaminergic agents. Two-week-old albino guinea pigs, selected for being myopic (range refractive error [RE], -2 to -10 diopters [D]), received unilateral peribulbar injections of apomorphine (nonselective dopamine receptor agonist; 0, 7.5, 25, 75, 250, 750, and 2500 ng; n = 112), SKF38393 (D1-like agonist; 0, 10, 100, 1000 ng; n = 63), SCH23390 (D1-like antagonist; 0, 2500 ng; n = 27), quinpirole (D2-like agonist; 0, 10, 100, 1000 ng; n = 58), or sulpiride (D2-like antagonist; 0, 2500 ng; n = 24) once a day for four weeks. One noninjected group (n = 19) served as untreated control. Refractive states and axial dimensions of the eyes were measured without cycloplegia or general anesthetic, using eccentric infrared photoretinoscopy and A-scan ultrasonography, respectively, before treatment, and after 2 and 4 weeks of treatment. The main drug effects were analyzed by paired t-test or 2-way repeated measures ANOVA, as required. The naturally occurring progression of myopic RE was inhibited by apomorphine at relatively high doses (250 and 750 ng), SKF38393 at 100 ng (D1-like agonist), and sulpiride at 2500 ng (D2-like antagonist), but promoted by apomorphine at a lower dose (25 ng), quinpirole at 100 ng (D2-like agonist), and SCH23390 at 2500 ng (D1-like antagonist). All drugs affected primarily vitreous chamber depth, rather than anterior segment dimensions. Our data suggest that the activation of D1-like receptors inhibits, whereas activation of D2-like receptors promotes, progressive myopia in this animal model. The robust effects of antagonists

Mesolimbic and Nigrostriatal Dopaminergic Systems: Behavioral Neuropharmacology.

DTIC Science & Technology

1985-08-01

presented in Table Table III List of drugs D ru gVeh i c l e Intracerebral infusions Dopamine agonist~s Apomorphine hydrochloride 0.1% Na metabisulfite...saline GABA 0.9% saline Picrotoxin 0 .9%saline Systemic injections Dopamine agents d-Amphetamine sulfate 0.9% saline Aponiorphine hydrochloride 0.9...3H)methionine (15 Ci/mmole, lmCi/ml. 16 Amersham), 122 ul of freshly prepared pargyline hydrochloride (10.2 mM), 326 ul of I M Tris pH 10.8, 246 ul

PET Imaging of D2/3 agonist binding in healthy human subjects with the radiotracer [11C]-N-propyl-nor-apomorphine (NPA): preliminary evaluation and reproducibility studies

PubMed Central

Narendran, Rajesh; Frankle, W. Gordon; Mason, N. Scott; Laymon, Charles M.; Lopresti, Brian J; Price, Julie C.; Kendro, Steve; Vora, Shivangi; Litschge, Maralee; Mountz, James M.; Mathis, Chester A.

2009-01-01

Objective (-)-N-[11C]-Propyl-norapomorphine (NPA) is a full dopamine D2/3 receptor agonist radiotracer suitable for imaging D2/3 receptors configured in a state of high affinity for agonists using Positron Emission Tomography (PET). The aim of the present study was to define the optimal analytic method to derive accurate and reliable D2/3 receptor parameters with [11C]NPA. Methods Six healthy subjects (4 females/2 males) underwent two [11C]NPA scans in the same day. D2/3 receptor binding parameters were estimated using kinetic analysis (using 1- and 2- tissue compartment models) as well as simplified reference tissue method in the three functional subdivisions of the striatum (associative striatum, AST; limbic striatum LST and sensorimotor striatum SMST). The test-retest variability and intraclass correlation coefficient were assessed for distribution volume (VT), binding potential relative to plasma concentration (BPP), and binding potential relative to nondisplaceable uptake (BPND) Results A two-tissue compartment kinetic model adequately described the functional subdivisions of the striatum as well as cerebellum time-activity data. The reproducibility of VT was excellent (≤ 10%) in all regions, for this approach. The reproducibility of both BPP (≤ 12%) and BPND (≤ 10%) was also excellent. The intraclass correlation coefficient of BPP and BPND were acceptable as well (> 0.75) in the three functional subdivisions of the striatum. Although SRTM led to an underestimation of BPND values relative to that estimated by kinetic analysis by 8 to 13%, the values derived using both the methods were reasonably well correlated (r2 = 0.89, n = 84). Both methods were similarly effective at detecting the differences in [11C]NPA BPND between subjects. Conclusion The results of this study indicate that [11C]NPA can be used to measure D2/3 receptors configured in a state of high affinity for the agonists with high reliability and reproducibility in the functional subdivisions

Discrimination between olfactory receptor agonists and non-agonists.

PubMed

Topin, Jérémie; de March, Claire A; Charlier, Landry; Ronin, Catherine; Antonczak, Serge; Golebiowski, Jérôme

2014-08-11

A joint approach combining free-energy calculations and calcium-imaging assays on the broadly tuned human 1G1 olfactory receptor is reported. The free energy of binding of ten odorants was computed by means of molecular-dynamics simulations. This state function allows separating the experimentally determined eight agonists from the two non-agonists. This study constitutes a proof-of-principle for the computational deorphanization of olfactory receptors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the mechanism for PPAR agonists to enhance ABCA1 gene expression

PubMed Central

Ogata, Masaki; Tsujita, Maki; Hossain, Mohammad Anwar; Akita, Nobukatsu; Gonzalez, Frank J.; Staels, Bart; Suzuki, Shogo; Fukutomi, Tatsuya; Kimura, Genjiro; Yokoyama, Shinji

2009-01-01

Expression of ATP binding cassette transporter A1 (ABCA1), a major regulator of high density lipoprotein (HDL) biogenesis, is known to be up-regulated by the transcription factor liver X receptor (LXR) α, and expression is further enhanced by activation of the peroxisome proliferator activated receptors (PPARs). We investigated this complex regulatory network using specific PPAR agonists: four fibrates (fenofibrate, bezafibrate, gemfibrozil and LY518674), a PPAR δ agonist (GW501516) and a PPAR γ agonist (pioglitazone). All of these compounds increased the expression of LXRs, PPARs and ABCA1 mRNAs, and associated apoA-I-mediated lipid release in THP-1 macrophage, WI38 fibroblast and mouse fibroblast. When mouse fibroblasts lacking expression of PPAR α were examined, the effects of fenofibrate and LY518674 were markedly diminished while induction by other ligands were retained. The PPAR α promoter was activated by all of these compounds in an LXR α-dependent manner, and partially in a PPAR α-dependent manner, in mouse fibroblast. The LXR responsive element (LXRE)-luciferase activity was enhanced by all the compounds in an LXR α-dependent manner in mouse fibroblast. This activation was exclusively PPAR α-dependent by fenofibrate and LY518674, but nonexclusively by the others. We conclude that PPARs and LXRs are involved in the regulation of ABCA1 expression and HDL biogenesis in a cooperative signal transduction pathway. PMID:19201410

Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy

PubMed Central

Jakubík, J; Janíčková, H; El-Fakahany, EE; Doležal, V

2011-01-01

BACKGROUND AND PURPOSE Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5′-γ−thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M2 muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. EXPERIMENTAL APPROACH Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [35S]GTPγS and [3H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M2 muscarinic acetylcholine receptor. KEY RESULTS Agonists displayed biphasic competition curves with the antagonist [3H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [3H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from Gi/o G-proteins but only its dissociation from Gs/olf G-proteins. CONCLUSIONS AND IMPLICATIONS These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of Gi/o versus Gs/olf G-proteins that are not identified by conventional GTPγS binding. PMID:20958290

Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy.

PubMed

Jakubík, J; Janíčková, H; El-Fakahany, E E; Doležal, V

2011-03-01

Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5'-γ-thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M₂ muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [³⁵S]GTPγS and [³H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M₂ muscarinic acetylcholine receptor. Agonists displayed biphasic competition curves with the antagonist [³H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [³H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from G(i/o) G-proteins but only its dissociation from G(s/olf) G-proteins. These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of G(i/o) versus G(s/olf) G-proteins that are not identified by conventional GTPγS binding. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

A RETINOIC ACID β2-RECEPTOR AGONIST EXERTS CARDIOPROTECTIVE EFFECTS.

PubMed

Marino, Alice; Sakamoto, Takuya; Tang, Xiao-Han; Gudas, Lorraine J; Levi, Roberto

2018-06-15

We previously discovered that oral treatment with AC261066, a synthetic selective agonist for the retinoic acid β2-receptor (RARβ2), decreases oxidative stress in the liver, pancreas, and kidney of mice fed a high-fat diet (HFD). Since hyperlipidemic states are causally associated with myocardial ischemia and oxidative stress, we have now investigated the effects of AC261066 in an ex-vivo ischemia/reperfusion (I/R) injury model in hearts of two prototypic dysmetabolic mice. We found that a 6-week oral treatment with AC261066 in both genetically hypercholesterolemic (ApoE-/-) and obese (HFD-fed) wild-type mice exerts protective effects when their hearts are subsequently subjected to I/R ex vivo in the absence of added drug. In ApoE-/- mice this cardioprotection ensued without hyperlipidemic changes. Cardioprotection consisted of an attenuation of infarct size, diminution of norepinephrine (NE) spillover, and alleviation of reperfusion arrhythmias. This cardioprotection was associated with a reduction in oxidative stress and mast cell (MC) degranulation. We suggest that the reduction in myocardial injury and adrenergic activation, and the antiarrhythmic effects result from decreased formation of oxygen radicals and toxic aldehydes known to elicit the release of MC-derived renin, promoting the activation of local renin-angiotensin system (RAS) leading to enhanced NE release and reperfusion arrhythmias. Because these beneficial effects of AC261066 occurred at the ex-vivo level following oral drug treatment, our data suggest that AC261066 could be viewed as a therapeutic means to reduce I/R injury of the heart, and potentially also considered in the treatment of other cardiovascular ailments such as chronic arrhythmias, and cardiac failure. The American Society for Pharmacology and Experimental Therapeutics.

Species differences in the relative densities of D1- and D2-like dopamine receptor subtypes in the Japanese quail and rats: an in vitro quantitative receptor autoradiography study.

PubMed

Kleitz, Hayley K; Cornil, Charlotte A; Balthazart, Jacques; Ball, Gregory F

2009-01-01

Evidence has accumulated that the regulation of male sexual behavior by dopamine might not be the same in Japanese quail (and perhaps all birds) as it is in mammals. For example, the non-selective dopamine receptor agonist, apomorphine (APO), facilitates male sexual behavior in rats but inhibits it in quail. Although the general organization of the dopamine system is similar in birds and mammals, it is possible that the relative distribution and/or density of binding sites are different. We therefore compared the relative densities of D1-like and D2-like receptor subtypes in Japanese quail and rats, with the use of in vitro quantitative receptor autoradiography. Brain sections from 8 male rats and 8 male quail were labeled with [(3)H]SCH-23390 and [(3)H]Spiperone. In general we found a systematic species difference in the relative density of D1- vs. D2-like receptors such that the D2/D1 ratio is higher in quail than in rats in areas, known to be important target sites for dopamine action such as striatal regions or the preoptic area, which is also associated with activation of sexual behavior. This difference might explain the variation in the behavioral effectiveness of APO in rats as compared to quail; with a higher relative density of D2-like receptors in quail, a similar dose of APO would be more likely to activate inhibitory processes in quail than in rats. (c) 2009 S. Karger AG, Basel.

Sexual-incentive motivation and paced sexual behavior in female rats after treatment with drugs modifying dopaminergic neurotransmission.

PubMed

Ellingsen, Ellinor; Agmo, Anders

2004-03-01

The effects of the dopamine receptor agonist apomorphine, the dopamine releaser amphetamine, and the dopamine receptor antagonist cis(Z)-flupenthixol on sexual-incentive motivation and on paced-mating behavior were studied in female rats. Apomorphine, in the doses of 0.125 and 0.5 mg/kg, showed a tendency to reduce incentive motivation. Ambulatory activity was inhibited, evidenced both by diminished distance moved and reduced velocity of movement. Amphetamine (0.25 and 1 mg/kg) and flupenthixol (0.25 and 0.5 mg/kg) failed to modify incentive motivation while stimulating and reducing ambulatory activity, respectively. In the mating test, apomorphine enhanced the latency to enter the male's half and reduced the number of proceptive behaviors. However, these effects were associated with the appearance of stereotyped sniffing. Amphetamine increased the propensity to escape from the male after a mount without having other effects. Flupenthixol augmented the duration of the lordosis posture. Neither amphetamine nor flupenthixol affected sniffing. These data show that facilitated dopaminergic neurotransmission stimulates neither paced female sexual behavior nor sexual-incentive motivation. Dopamine receptor blockade has slight consequences. It is concluded that dopamine is not a transmitter of major importance for unconditioned female sexual motivation and behavior.

The epileptogenic spectrum of opiate agonists.

PubMed

Snead, O C; Bearden, L J

1982-11-01

The present authors gave mu, delta, kappa, epsilon and sigma opiate receptor agonists intracerebroventricularly to rats both singly and in combination while monitoring the electroencephalogram from cortical and depth electrodes. Dose-response curves were plotted with naloxone against the changes produced by each agonist, and the effect of a number of anticonvulsant drugs on agonist-induced seizures was ascertained. Each opiate agonist produced a different seizure pattern with a different naloxone dose-response curve and anticonvulsant profile. The order of convulsive potency was epsilon greater than delta greater than mu greater than sigma much greater than kappa. Petit mal-like seizure activity was unique to the delta agonist, leucine-enkephalin, while only the mu agonist, morphine produced generalized convulsive seizures. These experiments raise the possibility that opiate systems in the brain may be involved in the pathogenesis of a wide spectrum of seizure disorders.

Development of a rat model of sexual performance anxiety: effect of behavioural and pharmacological hyperadrenergic stimulation on APO-induced erections.

PubMed

Brien, S E; Smallegange, C; Gofton, W T; Heaton, J P W; Adams, M A

2002-04-01

As part of the multifactorial nature of erectile dysfunction, anxiety associated with sexual performance (SPA) remains a major contributing factor to its progression. In fact, the heightened sympathetic activity associated with sexual performance anxiety may be a key early component of this disruption of normal erectile responses. We are not aware that any animal models have been developed to assess this phenomenon. Using apomorphine (APO, 80 microg/kg s.c.)-induced erections in rats we characterised the effects of behavioural or pharmacological hyperadrenergic stimulation (that is, anxiety) on erections and hemodynamics. We developed an experimental SPA paradigm by exposing male rats to the stress of being observed by a larger, older male rat placed in close proximity to test rats during APO testing. In a separate group, adrenergic stress was simulated using a sympathomimetic, methoxamine (MXA) given prior to APO testing. In a third group, the changes in circulatory parameters (mean arterial pressure, heart rate) were determined following instrumentation with radiotelemetric transducers for each scenario. APO-induced erections were significantly lower in both the behavioural (1.25+/-0.8) and pharmacological (0.33+/-0.5) stressor paradigms compared to controls (2.81+/-0.9). Further, erections in MXA-treated rats were significantly lower than in the observed scenario. Despite the differences in erections hemodynamic assessments showed no differences in MAP or HR changes between the different experimental conditions. Thus, both the behavioural and pharmacological paradigms of SPA decreased erections, but did not affect the circulation. This suggests that the level of hyperadrenergic input required to induce erectile dysfunction can be subtle, and target only erectogenic pathways.

Evaluation of partial beta-adrenoceptor agonist activity.

PubMed

Lipworth, B J; Grove, A

1997-01-01

A partial beta-adrenoceptor (beta-AR) agonist will exhibit opposite agonist and antagonist activity depending on the prevailing degree of adrenergic tone or the presence of a beta-AR agonist with higher intrinsic activity. In vivo partial beta-AR agonist activity will be evident at rest with low endogenous adrenergic tone, as for example with chronotropicity (beta 1/beta 2), inotropicity (beta 1) or peripheral vasodilatation and finger tremor (beta 2). beta-AR blocking drugs which have partial agonist activity may exhibit a better therapeutic profile when used for hypertension because of maintained cardiac output without increased systemic vascular resistance, along with an improved lipid profile. In the presence of raised endogenous adrenergic tone such as exercise or an exogenous full agonist, beta-AR subtype antagonist activity will become evident in terms of effects on exercise induced heart rate (beta 1) and potassium (beta 2) responses. Reduction of exercise heart rate will occur to a lesser degree in the case of a beta-adrenoceptor blocker with partial beta 1-AR agonist activity compared with a beta-adrenoceptor blocker devoid of partial agonist activity. This may result in reduced therapeutic efficacy in the treatment of angina on effort when using beta-AR blocking drugs with partial beta 1-AR agonist activity. Effects on exercise hyperkalaemia are determined by the balance between beta 2-AR partial agonist activity and endogenous adrenergic activity. For predominantly beta 2-AR agonist such as salmeterol and salbutamol, potentiation of exercise hyperkalaemia occurs. For predominantly beta 2-AR antagonists such as carteolol, either potentiation or attenuation of exercise hyperkalaemia occurs at low and high doses respectively. beta 2-AR partial agonist activity may also be expressed as antagonism in the presence of an exogenous full agonist, as for example attenuation of fenoterol induced responses by salmeterol. Studies are required to investigate whether

Rescuing effects of RXR agonist bexarotene on aging-related synapse loss depend on neuronal LRP1.

PubMed

Tachibana, Masaya; Shinohara, Mitsuru; Yamazaki, Yu; Liu, Chia-Chen; Rogers, Justin; Bu, Guojun; Kanekiyo, Takahisa

2016-03-01

Apolipoprotein E (apoE) plays a critical role in maintaining synaptic integrity by transporting cholesterol to neurons through the low-density lipoprotein receptor related protein-1 (LRP1). Bexarotene, a retinoid X receptor (RXR) agonist, has been reported to have potential beneficial effects on cognition by increasing brain apoE levels and lipidation. To investigate the effects of bexarotene on aging-related synapse loss and the contribution of neuronal LRP1 to the pathway, forebrain neuron-specific LRP1 knockout (nLrp1(-/-)) and littermate control mice were administered with bexarotene-formulated diet (100mg/kg/day) or control diet at the age of 20-24 months for 8 weeks. Upon bexarotene treatment, levels of brain apoE and ATP-binding cassette sub-family A member 1 (ABCA1) were significantly increased in both mice. While levels of PSD95, glutamate receptor 1 (GluR1), and N-methyl-d-aspartate receptor NR1 subunit (NR1), which are key postsynaptic proteins that regulate synaptic plasticity, were decreased with aging, they were restored by bexarotene treatment in the brains of control but not nLrp1(-/-) mice. These results indicate that the beneficial effects of bexarotene on synaptic integrity depend on the presence of neuronal LRP1. However, we also found that bexarotene treatment led to the activation of glial cells, weight loss and hepatomegaly, which are likely due to hepatic failure. Taken together, our results demonstrate that apoE-targeted treatment through the RXR pathway has a potential beneficial effect on synapses during aging; however, the therapeutic application of bexarotene requires extreme caution due to its toxic side effects. Copyright © 2015 Elsevier Inc. All rights reserved.

Naloxone-blocked depriming effect of anxiolytic selank on apomorphine-induced behavioral manifestations of hyperfunction of dopamine system.

PubMed

Meshavkin, V K; Kost, N V; Sokolov, O Yu; Zolotarev, Yu A; Myasoedov, N F; Zozulya, A A

2006-11-01

Peptide anxiolytic selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) applied intraperitoneally in doses of 0.01, 0.1, 1.0, and 10.0 mg/kg to mice reduces behavioral manifestations of dopaminergic system induced by apomorphine in the verticalization test. This effect was comparable to that of atypical antipsychotic olanzapine in near-therapeutic doses (0.1 and 1.0 mg/kg, intraperitoneally) and was blocked with nonselective opioid receptor antagonist naloxone (10 mg/kg, intraperitoneally). Radioreceptor assay showed that selank did not displace nonselective D2-dopamine receptor antagonist (3)H-spiperone (EC50>100 microM) and delta- and micro-opioid receptor ligand 3H-DADLE (EC50>40 microM) from specific binding sites on rat brain membranes. It is hypothesized that the revealed behavioral effect of selank is mediated by its modulating effect on the endogenous opioid system and specifically, by its effect on activity of enkephalin-degrading enzymes.

Cortical oscillations scan using chirp-evoked potentials in 6-hydroxydopamine rat model of Parkinson's disease.

PubMed

Pérez-Alcázar, Marta; Nicolás, María Jesús; Valencia, Miguel; Alegre, Manuel; López-Azcárate, Jon; Iriarte, Jorge; Artieda, Julio

2010-01-15

There has been a growing interest during the last years on the relationship between Parkinson's disease and changes in the oscillatory activity, mostly in the cortico-basal motor loop. As Parkinson's disease (PD) is not limited to motor symptoms, it is logical to assume that the changes in oscillatory activity are not limited to this loop. Steady-state responses (SSR) are the result of averaging individual responses to trains of rhythmic stimuli delivered at a constant frequency. The amplitude of the response varies depending on the stimulus modality and stimulation rate, with a frequency of maximal response that is probably associated to the working frequency of the pathway involved. The study of SSR may be of interest in PD as a non-invasive test of cortical oscillatory activity. Our aim was to study the changes in auditory steady-state responses (ASSR) in the 6-hydroxydopamine (6-OHDA) model of Parkinson's disease in rats. We recorded the ASSR over the auditory cortex in a group of 10 control and 17 6-OHDA lesioned rats (the latter before and after the administration of the dopaminergic agonist apomorphine) both awake and under anesthesia with ketamine/xylazine, using chirp-modulated stimuli. The three conditions (control, lesion, lesion plus apomorphine) were compared with special emphasis on the amplitude, inter-trial phase coherence, and frequency of maximal response. A reduction in the frequency of maximal response (between 40 and 60 Hz) was observed in the 6-OHDA lesioned rats that was normalized after apomorphine injection. The administration of this dopaminergic agonist also reduced the inter-trial phase coherence of the response in frequencies above 170 Hz. These findings suggest that the nigrostriatal dopaminergic system may be involved in the regulation of oscillatory activity not only in motor circuits, but also in sensory responses. Copyright 2009 Elsevier B.V. All rights reserved.

Kappa Opioid Receptor Agonist and Brain Ischemia

PubMed Central

Chunhua, Chen; Chunhua, Xi; Megumi, Sugita; Renyu, Liu

2014-01-01

Opioid receptors, especially Kappa opioid receptor (KOR) play an important role in the pathophysiological process of cerebral ischemia reperfusion injury. Previously accepted KOR agonists activity has included anti-nociception, cardiovascular, anti-pruritic, diuretic, and antitussive effects, while compelling evidence from various ischemic animal models indicate that KOR agonist have neuroprotective effects through various mechanisms. In this review, we aimed to demonstrate the property of KOR agonist and its role in global and focal cerebral ischemia. Based on current preclinical research, the KOR agonists may be useful as a neuroprotective agent. The recent discovery of salvinorin A, highly selective non-opioid KOR agonist, offers a new tool to study the role of KOR in brain HI injury and the protective effects of KOR agonist. The unique pharmacological profile of salvinorin A along with the long history of human usage provides its high candidacy as a potential alternative medication for brain HI injury. PMID:25574482

Structural studies unravel the active conformation of apo RORγt nuclear receptor and a common inverse agonism of two diverse classes of RORγt inhibitors.

PubMed

Li, Xiang; Anderson, Marie; Collin, Delphine; Muegge, Ingo; Wan, John; Brennan, Debra; Kugler, Stanley; Terenzio, Donna; Kennedy, Charles; Lin, Siqi; Labadia, Mark E; Cook, Brian; Hughes, Robert; Farrow, Neil A

2017-07-14

The nuclear receptor retinoid acid receptor-related orphan receptor γt (RORγt) is a master regulator of the Th17/IL-17 pathway that plays crucial roles in the pathogenesis of autoimmunity. RORγt has recently emerged as a highly promising target for treatment of a number of autoimmune diseases. Through high-throughput screening, we previously identified several classes of inverse agonists for RORγt. Here, we report the crystal structures for the ligand-binding domain of RORγt in both apo and ligand-bound states. We show that apo RORγt adopts an active conformation capable of recruiting coactivator peptides and present a detailed analysis of the structural determinants that stabilize helix 12 (H12) of RORγt in the active state in the absence of a ligand. The structures of ligand-bound RORγt reveal that binding of the inverse agonists disrupts critical interactions that stabilize H12. This destabilizing effect is supported by ab initio calculations and experimentally by a normalized crystallographic B-factor analysis. Of note, the H12 destabilization in the active state shifts the conformational equilibrium of RORγt toward an inactive state, which underlies the molecular mechanism of action for the inverse agonists reported here. Our findings highlight that nuclear receptor structure and function are dictated by a dynamic conformational equilibrium and that subtle changes in ligand structures can shift this equilibrium in opposite directions, leading to a functional switch from agonists to inverse agonists. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Adverse Effects of GLP-1 Receptor Agonists

PubMed Central

Filippatos, Theodosios D.; Panagiotopoulou, Thalia V.; Elisaf, Moses S.

2014-01-01

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of injective anti-diabetic drugs that improve glycemic control and many other atherosclerosis-related parameters in patients with type 2 diabetes (T2D). However, the use of this relatively new class of drugs may be associated with certain adverse effects. Concerns have been expressed regarding the effects of these drugs on pancreatic and thyroid tissue, since animal studies and analyses of drug databases indicate an association of GLP-1 receptor agonists with pancreatitis, pancreatic cancer, and thyroid cancer. However, several meta-analyses failed to confirm a cause-effect relation between GLP-1 receptor agonists and the development of these adverse effects. One benefit of GLP-1 receptor agonists is that they do not cause hypoglycemia when combined with metformin or thiazolidinediones, but the dose of concomitant sulphonylurea or insulin may have to be decreased to reduce the risk of hypoglycemic episodes. On the other hand, several case reports have linked the use of these drugs, mainly exenatide, with the occurrence of acute kidney injury, primarily through hemodynamic derangement due to nausea, vomiting, and diarrhea. The most common symptoms associated with the use of GLP-1 receptor agonists are gastrointestinal symptoms, mainly nausea. Other common adverse effects include injection site reactions, headache, and nasopharyngitis, but these effects do not usually result in discontinuation of the drug. Current evidence shows that GLP-1 receptor agonists have no negative effects on the cardiovascular risk of patients with T2D. Thus, GLP-1 receptor agonists appear to have a favorable safety profile, but ongoing trials will further assess their cardiovascular effects. The aim of this review is to analyze critically the available data regarding adverse events of GLP-1 receptor agonists in different anatomic systems published in Pubmed and Scopus. Whenever possible, certain differences between GLP-1

Beta-agonists and animal welfare

USDA-ARS?s Scientific Manuscript database

The use of beta-agonists in animal feed is a high profile topic within the U.S. as consumers and activist groups continue to question its safety. The only beta-agonist currently available for use in swine is ractopamine hydrochloride (RAC). This is available as Paylean™ (Elanco Animal Health – FDA a...

Long-term studies of dopamine agonists.

PubMed

Hubble, Jean P

2002-02-26

Dopamine agonists have long been used as adjunctive therapy for the treatment of Parkinson's disease (PD). In more recent years these drugs have also been proved safe and effective as initial therapy in lieu of levodopa in the treatment of PD. Long-term levodopa therapy is associated with motor complications, including fluctuating response patterns and dyskinesia. By initially introducing a dopamine agonist as symptomatic drug therapy, it may be possible to postpone the use of levodopa and delay or prevent the development of motor complications. Recently, four clinical trials have explored this hypothesis by comparing the long-term response and side effects of levodopa with dopamine agonist therapy. The drugs studied have included ropinirole, pramipexole, cabergoline, and pergolide. In each of these projects, the occurrence of motor complications, such as wearing off and dyskinesia, was significantly less in the subjects assigned to initiation of therapy with a dopamine agonist. The addition of levodopa could be postponed by many months or even several years. Therefore, these long-term studies of dopamine agonists support the initiation of a dopamine agonist instead of levodopa in an effort to postpone levodopa-related motor complications. This therapeutic approach may be particularly appropriate in PD patients with a long treatment horizon on the basis of age and general good health. The extension phase of the long-term study comparing pramipexole with levodopa is ongoing, and follow-up information may help to establish the value of this treatment strategy.

Evaluation of AhR-agonists and AhR-agonist activity in sediments of Liaohe River protected areas, China.

PubMed

Zhang, Yun; Ke, Xin; Gui, Shaofeng; Wu, Xiaoqiong; Wang, Chunyong; Zhang, Haijun

2017-02-15

A total of 9 sediment samples of Liaohe River protected areas were collected to evaluate aryl hydrocarbon receptor agonists (AhR-agonists) and AhR-agonist activity via chemical analysis and in vitro H4IIE cell bioassay. Results indicated that bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (Bio-TEQs) ranged from 89.1 to 251.1pg/g dry weight. Concentrations of 16 EPA polycyclic aromatic hydrocarbons (PAHs), 12 dioxin-like polychlorinated biphenyls (PCBs), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) ranged from 256.8 to 560.1ng/g, 79.2 to 416.2pg/g, and 199.6 to 538.4pg/g, respectively. According to potency balance analysis, TEQ chem s based on PAHs, PCBs, and PCDD/Fs could contribute 16.56% to 26.11% of Bio-TEQs. This could be explained by the potential existence of unidentified AhR-agonists and the potential non-additive interactions among AhR-agonists in sediment extracts. Through the different contributions to Bio-TEQs, this study confirms that PCDD/Fs were the main pollutants that induced significantly AhR-agonist activity in sediments of Liaohe River protected areas. Copyright © 2016. Published by Elsevier Ltd.

Lipid and apolipoproteins (ApoAI, ApoB, Apo CIII, ApoE) disturbance in hemodialysis (HD) and renal transplant (Tx) patients.

PubMed

Janicki, Krzysztof; Solski, Janusz; Janicka, Lucyna; Kimak, Elzbieta; Bednarek-Skublewska, Anna; Stettner, Seweryn; Molas, Grzegorz

2004-01-01

The aim of the study was to evaluate the serum lipid and apolipoprotein profiles among patients after renal transplantation (Tx) and to compare them with the profiles obtained for permanently hemodialysed patients (HD). The investigations were performed at 15 Tx, 40 HD patients and the control group of 40 healthy subjects. There were significantly increased TG, ApoAIII, ApoE, TC/ HDL-C, ApoCIII non B, ApoCIII:B and decreased HDL-C, ApoAI, HDL-C/ApoAI, ApoAI/ApoCIII, ApoB/ApoCIII ratios comparing HD patients to the control group. There were increased TG, ApoCIII, ApoCIII non B, ApoB/ApoCIII ratios and decreased ApoAI/ApoCIII ratios in Tx patients as compared to the control subjects. Moreover, there were significantly higher HDL, ApoAI, HDL/ApoAI, ApoCIII non B and lower ApoE, ApoE/ApoB, ApoCIII:B ratios in Tx patients as compared to these of HD patients. Significant inverse correlation of the time which passed from executed Tx and ApoCIII:B ratio (r = -0.67; p < 0.01) at renal transplant patients were observed, which means the diminished risk of development of atherosclerosis.

Comparative cognitive effects of bilateral subthalamic stimulation and subcutaneous continuous infusion of apomorphine in Parkinson's disease.

PubMed

Alegret, Montse; Valldeoriola, Francesc; Martí, MaJosé; Pilleri, Manuela; Junqué, Carme; Rumià, Jordi; Tolosa, Eduardo

2004-12-01

Bilateral subthalamic deep brain stimulation (STN-DBS) and continuous subcutaneous infusion of apomorphine (APM-csi) can provide a comparable improvement on motor function in patients with advanced Parkinson's disease (PD), but the mechanisms by which both therapies exert their effects are different. We analyzed the cognitive effects of APM-csi. We also compared neuropsychological effects induced by STN-DBS and APM-csi in advanced PD to ascertain the neuropsychological aspects relevant in determining the therapeutic procedure that is the most appropriate in a particular patient. We studied 9 patients treated with STN-DBS and 7 patients with APM-csi. Neuropsychological measures included Rey's Auditory-Verbal Learning, Stroop, Trail Making, phonetic verbal fluency, and Judgment of Line Orientation tests. In the APM-csi group, significant changes were not observed in the neuropsychological tests performance. By contrast, in the STN-DBS group, moderate worsening was found in phonetic verbal fluency and Stroop Naming scores that was partially reversible at long-term follow-up and did not have consequences on regular activities. Consequently, these findings could be interpreted as being not relevant in deciding the most suitable treatment in a given patient. 2004 Movement Disorder Society.

Modification of kindled amygdaloid seizures by opiate agonists and antagonists.

PubMed

Albertson, T E; Joy, R M; Stark, L G

1984-03-01

The effects of 19 opiate agonists and antagonists on kindled amygdaloid seizures in the rat were studied. The mu agonists tended to reduce the length of elicited afterdischarges and behavioral ranks, while markedly increasing postictal electroencephalogram spikes and behavioral arrest time. These effects were reversed by naloxone. The kappa agonists reduced behavioral rank and variably reduced afterdischarge length with a concomitant lengthening of postictal behavioral arrest time and number of electroencephalogram spikes. The putative sigma agonist, SKF 10,047, reduced afterdischarge durations only at the higher doses tested. The decreases found after the sigma agonists in postictal electroencephalogram spiking and time of behavioral arrest were not reversed by naloxone. Only the lower doses of normeperidine were found to decrease seizure thresholds. The mixed agonist/antagonists (MAA) cyclazocine and cyclorphan markedly increased seizure threshold and reduced afterdischarge duration and behavioral rank. Only the MAA pentazocine tended to increase threshold but not suprathreshold afterdischarge durations. The order of ability to modify the ictal events was MAA (selected) greater than kappa agonists greater than mu agonists greater than sigma agonists. The increase in postictal events (behavior arrest and spikes) was caused most effectively by pretreatment with mu agonist greater than kappa agonist greater than selected MAA greater than sigma agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Dopamine agonists in the treatment of Parkinson's disease.

PubMed

Bonuccelli, Ubaldo; Pavese, Nicola

2006-01-01

Dopamine agonists are highly effective as adjunctive therapy to levodopa in advanced Parkinson's disease and have rapidly gained popularity as a monotherapy in the early stages of Parkinson's disease for patients less than 65-70 years old. In the latter case, dopamine agonists are about as effective as levodopa but patients demonstrate a lower tendency to develop motor complications. However, dopamine agonists lose efficacy over time and the number of patients remaining on agonist monotherapy decreases to less than 50% after 3 years of treatment. Thus, after a few years of treatment the majority of patients who started on dopamine agonists will be administered levodopa, in a combined dopaminergic therapy, in order to achieve a better control of motor symptoms.

Dopamine agonist withdrawal syndrome: implications for patient care.

PubMed

Nirenberg, Melissa J

2013-08-01

Dopamine agonists are effective treatments for a variety of indications, including Parkinson's disease and restless legs syndrome, but may have serious side effects, such as orthostatic hypotension, hallucinations, and impulse control disorders (including pathological gambling, compulsive eating, compulsive shopping/buying, and hypersexuality). The most effective way to alleviate these side effects is to taper or discontinue dopamine agonist therapy. A subset of patients who taper a dopamine agonist, however, develop dopamine agonist withdrawal syndrome (DAWS), which has been defined as a severe, stereotyped cluster of physical and psychological symptoms that correlate with dopamine agonist withdrawal in a dose-dependent manner, cause clinically significant distress or social/occupational dysfunction, are refractory to levodopa and other dopaminergic medications, and cannot be accounted for by other clinical factors. The symptoms of DAWS include anxiety, panic attacks, dysphoria, depression, agitation, irritability, suicidal ideation, fatigue, orthostatic hypotension, nausea, vomiting, diaphoresis, generalized pain, and drug cravings. The severity and prognosis of DAWS is highly variable. While some patients have transient symptoms and make a full recovery, others have a protracted withdrawal syndrome lasting for months to years, and therefore may be unwilling or unable to discontinue DA therapy. Impulse control disorders appear to be a major risk factor for DAWS, and are present in virtually all affected patients. Thus, patients who are unable to discontinue dopamine agonist therapy may experience chronic impulse control disorders. At the current time, there are no known effective treatments for DAWS. For this reason, providers are urged to use dopamine agonists judiciously, warn patients about the risks of DAWS prior to the initiation of dopamine agonist therapy, and follow patients closely for withdrawal symptoms during dopamine agonist taper.

Structure/function relationships of calcitonin analogues as agonists, antagonists, or inverse agonists in a constitutively activated receptor cell system.

PubMed

Pozvek, G; Hilton, J M; Quiza, M; Houssami, S; Sexton, P M

1997-04-01

The structure/function relationship of salmon calcitonin (sCT) analogues was investigated in heterologous calcitonin receptor (CTR) expression systems. sCT analogues with progressive amino-terminal truncations intermediate of sCT-(1-32) to sCT-(8-32) were examined for their ability to act as agonists, antagonists, or inverse agonists. Two CTR cell clones, B8-H10 and G12-E12, which express approximately 5 million and 25,000 C1b receptors/cell, respectively, were used for this study. The B8-H10 clone has an approximately 80-fold increase in basal levels of intracellular cAMP due to constitutive activation of the overexpressed receptor. In whole-cell competition binding studies, sCT-(1-32) was more potent than any of its amino-terminally truncated analogues in competition for 125I-sCT binding. In cAMP accumulation studies, sCT-(1-32) and modified analogues sCT-(2-32) and sCT-(3-32) had agonist activities. SDZ-216-710, with an amino-terminal truncation of four amino acids, behaved as a partial agonist/antagonist, whereas amino-terminal truncations of six or seven amino acid residues produced a 16-fold reduction in basal cAMP levels and attenuated the response to the agonist sCT-(1-32) in the constitutively active CTR system. This inverse agonist effect was insensitive to pertussis toxin inhibition. In contrast, the inverse agonist activity of these peptides was not observed in the nonconstitutively active CTR system, in which sCT analogues with amino-terminal truncations of four or more amino acids behaved as neutral competitive antagonists. These results suggest that the inverse agonist activity is mediated by stabilization of the inactive state of the receptor, which does not couple to G protein, and attenuates basal signaling initiated by ligand-independent activation of the effector adenylyl cyclase.

Identification of Determinants Required for Agonistic and Inverse Agonistic Ligand Properties at the ADP Receptor P2Y12

PubMed Central

Schmidt, Philipp; Ritscher, Lars; Dong, Elizabeth N.; Hermsdorf, Thomas; Cöster, Maxi; Wittkopf, Doreen; Meiler, Jens

2013-01-01

The ADP receptor P2Y12 belongs to the superfamily of G protein–coupled receptors (GPCRs), and its activation triggers platelet aggregation. Therefore, potent antagonists, such as clopidogrel, are of high clinical relevance in prophylaxis and treatment of thromboembolic events. P2Y12 displays an elevated basal activity in vitro, and as such, inverse agonists may be therapeutically beneficial compared with antagonists. Only a few inverse agonists of P2Y12 have been described. To expand this limited chemical space and improve understanding of structural determinants of inverse agonist-receptor interaction, this study screened a purine compound library for lead structures using wild-type (WT) human P2Y12 and 28 constitutively active mutants. Results showed that ATP and ATP derivatives are agonists at P2Y12. The potency at P2Y12 was 2-(methylthio)-ADP > 2-(methylthio)-ATP > ADP > ATP. Determinants required for agonistic ligand activity were identified. Molecular docking studies revealed a binding pocket for the ATP derivatives that is bordered by transmembrane helices 3, 5, 6, and 7 in human P2Y12, with Y105, E188, R256, Y259, and K280 playing a particularly important role in ligand interaction. N-Methyl-anthraniloyl modification at the 3′-OH of the 2′-deoxyribose leads to ligands (mant-deoxy-ATP [dATP], mant-deoxy-ADP) with inverse agonist activity. Inverse agonist activity of mant-dATP was found at the WT human P2Y12 and half of the constitutive active P2Y12 mutants. This study showed that, in addition to ADP and ATP, other ATP derivatives are not only ligands of P2Y12 but also agonists. Modification of the ribose within ATP can result in inverse activity of ATP-derived ligands. PMID:23093496

Agonist-Directed Desensitization of the β2-Adrenergic Receptor

PubMed Central

Goral, Vasiliy; Jin, Yan; Sun, Haiyan; Ferrie, Ann M.; Wu, Qi; Fang, Ye

2011-01-01

The β2-adrenergic receptor (β2AR) agonists with reduced tachyphylaxis may offer new therapeutic agents with improved tolerance profile. However, receptor desensitization assays are often inferred at the single signaling molecule level, thus ligand-directed desensitization is poorly understood. Here we report a label-free biosensor whole cell assay with microfluidics to determine ligand-directed desensitization of the β2AR. Together with mechanistic deconvolution using small molecule inhibitors, the receptor desensitization and resensitization patterns under the short-term agonist exposure manifested the long-acting agonism of salmeterol, and differentiated the mechanisms of agonist-directed desensitization between a full agonist epinephrine and a partial agonist pindolol. This study reveals the cellular mechanisms of agonist-selective β2AR desensitization at the whole cell level. PMID:21541288

ApoE polymorphisms in narcolepsy

PubMed Central

Gencik, Martin; Dahmen, Norbert; Wieczorek, Stefan; Kasten, Meike; Gencikova, Alexandra; Epplen, Jorg T

2001-01-01

Background Narcolepsy is a common neuropsychiatric disorder characterized by increased daytime sleepiness, cataplexy and hypnagogic hallucinations. Deficiency of the hypocretin neurotransmitter system was shown to be involved in the pathogenesis of narcolepsy in animals and men. There are several hints that neurodegeneration of hypocretin producing neurons in the hypothalamus is the pathological correlate of narcolepsy. The ApoE4 allele is a major contributing factor to early-onset neuronal degeneration in Alzheimer disease and other neurodegenerative diseases as well. Methods To clarify whether the ApoE4 phenotype predisposes to narcolepsy or associates with an earlier disease onset, we have genotyped the ApoE gene in 103 patients with narcolepsy and 101 healthy controls. Results The frequency of the E4 allele of the ApoE gene was 11% in the patient and 15% in the control groups. Furthermore, the mean age of onset did not differ between the ApoE4+ and ApoE4- patient groups. Conclusion Our results exclude the ApoE4 allele as a major risk factor for narcolepsy. PMID:11560764

Sports doping: emerging designer and therapeutic β2-agonists.

PubMed

Fragkaki, A G; Georgakopoulos, C; Sterk, S; Nielen, M W F

2013-10-21

Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future. © 2013.

Mixed Kappa/Mu Opioid Receptor Agonists: The 6β-Naltrexamines

PubMed Central

Cami-Kobeci, Gerta; Neal, Adrian P.; Bradbury, Faye A.; Purington, Lauren C.; Aceto, Mario D.; Harris, Louis S.; Lewis, John W.; Traynor, John R.; Husbands, Stephen M.

2011-01-01

Ligands from the naltrexamine series have consistently demonstrated agonist activity at kappa opioid receptors (KOR), with varying activity at the mu opioid receptor (MOR). Various 6β-cinnamoylamino derivatives were made with the aim of generating ligands with a KOR agonist/MOR partial agonist profile, as ligands with this activity may be of interest as treatment agents for cocaine abuse. The ligands all displayed the desired high affinity, non-selective binding in vitro and in the functional assays were high efficacy KOR agonists with some partial agonist activity at MOR. Two of the new ligands (12a, 12b) have been evaluated in vivo, with 12a acting as a KOR agonist, and therefore somewhat similar to the previously evaluated analogues 3–6, while 12b displayed predominant MOR agonist activity. PMID:19253970

Exploring the binding energy profiles of full agonists, partial agonists, and antagonists of the α7 nicotinic acetylcholine receptor.

PubMed

Tabassum, Nargis; Ma, Qianyun; Wu, Guanzhao; Jiang, Tao; Yu, Rilei

2017-09-01

Nicotinic acetylcholine receptors (nAChRs) belong to the Cys-loop receptor family and are important drug targets for the treatment of neurological diseases. However, the precise determinants of the binding efficacies of ligands for these receptors are unclear. Therefore, in this study, the binding energy profiles of various ligands (full agonists, partial agonists, and antagonists) were quantified by docking those ligands with structural ensembles of the α7 nAChR exhibiting different degrees of C-loop closure. This approximate treatment of interactions suggested that full agonists, partial agonists, and antagonists of the α7 nAChR possess distinctive binding energy profiles. Results from docking revealed that ligand binding efficacy may be related to the capacity of the ligand to stabilize conformational states with a closed C loop.

Epigenetic regulation of the TRAIL/Apo2L apoptotic pathway by histone deacetylase inhibitors: an attractive approach to bypass melanoma immunotherapy resistance

PubMed Central

Jazirehi, Ali R; Arle, Dylan

2013-01-01

TNF-related apoptosis-inducing ligand (TRAIL/Apo2L) is a major cytotoxic mechanism employed by cytotoxic T lymphocytes (CTL) and natural killer (NK) cells to eradicate malignant cells. TRAIL/Apo2L interacts with its cognate receptors located on tumor cell surface namely, TRAIL-R1 (DR4), TRAIL-R2 (DR5), TRAIL-R3 (DcR1), TRAIL-R4 (DcR2) and osteoprotegerin (OPG). The exact function of DcR1 and DcR2 remains elusive. TRAIL/Apo2L or agonistic monoclonal antibodies directed against TRAIL/Apo2L death-inducing receptors (DR4, DR5) have become an attractive immunological therapeutic tools in clinical oncology due to their selective killing of tumors and lack of affinity towards healthy cells. Though a potent anti-cancer modality, some cancer cells exhibit inherent or acquired resistance to TRAIL/Apo2L. Postulated resistance mechanisms include up-regulation of c-FLIP, down-regulation of caspase-8, down-regulation/shedding of death receptors and an imbalanced ratio of pro- to anti-apoptotic genes due to aberrant activity of cellular survival signal transduction pathways. The development of resistance has spurred the use of combination therapy, in particular using small molecule sensitizing agents, to restore apoptosis sensitivity. A novel category of such compounds is histone deacetylase inhibitors (HDACi), which block HDACs from removing acetyl groups from histone tails thereby preventing silencing of pro-apoptotic genes and regulating the expression of non-histone proteins (i.e., apoptosis-associated genes), are effective agents in some malignancies. Some HDACi, such as Suberoylanilide Hydroxamic Acid (SAHA), have received FDA approval for cancer treatment. In various melanoma preclinical models, HDACi in conjunction with TRAIL/Apo2L, via modulation of apoptotic machinery, have proven to overcome acquired/inherent resistance to either agent. Here, we discuss recent findings on the role of TRAIL/Apo2L and its agonistic mAbs in melanoma immunotherapy with discussions on

New thrombopoietin receptor agonists for platelet disorders.

PubMed

Homeida, S; Ebdon, C; Batty, P; Jackson, B; Kolade, S; Bateman, C; Peng, Y Y; Stasi, R

2012-04-01

Since thrombopoietin (TPO) was cloned in 1994, TPO receptor (TPO-R) agonists have been developed which have shown significant clinical activity in various conditions characterized by thrombocytopenia. First-generation TPO-R agonists were recombinant forms of human TPO. The clinical development of these molecules was discontinued after one of them, pegylated recombinant human megakaryocyte growth and development factor, was associated with the development of neutralizing autoantibodies cross-reacting with endogenous TPO. Second-generation TPO-R agonists are now available, which present no sequence homology to endogenous TPO. Two of these new agents, romiplostim and eltrombopag, have been granted marketing authorization for use in patients with primary immune thrombocytopenia unresponsive to conventional treatments. Clinical trials with TPO-R agonists are also ongoing in other thrombocytopenias, such as hepatitis C virus-related thrombocytopenia and the myelodysplastic syndromes. Copyright 2012 Prous Science, S.A.U. or its licensors. All rights reserved.

Frontal Decortication and Adaptive Changes in Striatal Cholinergic Neurons: Neuropharmacological and Behavioral Implications

DTIC Science & Technology

1989-11-24

ACh); choline (Oh); apomnorphine (APO); oxotremorine (OTMN); OXI, oxiracetam; SDHACU, sodium-dependent high affinity choline uptake: PC...control group, Dunnett’s test. TABLE 3- Restoration of the ACh increasing effect of oxotremorine by piracetam in DC rats. Striatal ACh content (nmoles/g...ACh content induced by oxotremorine and apomorphine useful model for studying means to restore the deficit in stria- acting at muscarine and dopamine

Sensitivity of GBM cells to cAMP agonist-mediated apoptosis correlates with CD44 expression and agonist resistance with MAPK signaling.

PubMed

Daniel, Paul M; Filiz, Gulay; Mantamadiotis, Theo

2016-12-01

In some cell types, activation of the second messenger cAMP leads to increased expression of proapoptotic Bim and subsequent cell death. We demonstrate that suppression of the cAMP pathway is a common event across many cancers and that pharmacological activation of cAMP in glioblastoma (GBM) cells leads to enhanced BIM expression and apoptosis in specific GBM cell types. We identified the MAPK signaling axis as the determinant of cAMP agonist sensitivity in GBM cells, with high MAPK activity corresponding to cAMP resistance and low activity corresponding to sensitization to cAMP-induced apoptosis. Sensitive cells were efficiently killed by cAMP agonists alone, while targeting both the cAMP and MAPK pathways in resistant GBM cells resulted in efficient apoptosis. We also show that CD44 is differentially expressed in cAMP agonist-sensitive and -resistant cells. We thus propose that CD44 may be a useful biomarker for distinguishing tumors that may be sensitive to cAMP agonists alone or cAMP agonists in combination with other pathway inhibitors. This suggests that using existing chemotherapeutic compounds in combination with existing FDA-approved cAMP agonists may fast track trials toward improved therapies for difficult-to-treat cancers, such as GBM.

Modification of opiate agonist binding by pertussis toxin

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

Abood, M.E.; Lee, N.M.; Loh, H.H.

1986-03-05

Opiate agonist binding is decreased by GTP, suggesting the possible involvement of GTP binding proteins in regulation of opiate receptor binding. This possibility was addressed by asking whether pertussis toxin treatment, which results in ADP-ribosylation and modification of G proteins, would alter opiate agonist binding. The striatum was chosen for the initial brain area to be studied, since regulation of opiate action in this area had been shown to be modified by pertussis toxin. Treatment of striatal membranes with pertussis toxin results in up to a 55% decrease in /sup 3/(H)-DADLE binding as compared with membranes treated identically without toxin.more » This corresponds to a near complete ADP-ribosylation of both G proteins in the striatal membrane. The decrease in agonist binding appears to be due to an altered affinity of the receptor for agonist as opposed to a decrease in the number of sites. This effect of pertussis toxin on opiate agonist binding demonstrates the actual involvement of G proteins in regulation of opiate receptor binding.« less

Reciprocity of agonistic support in ravens.

PubMed

Fraser, Orlaith N; Bugnyar, Thomas

2012-01-01

Cooperative behaviour through reciprocation or interchange of valuable services in primates has received considerable attention, especially regarding the timeframe of reciprocation and its ensuing cognitive implications. Much less, however, is known about reciprocity in other animals, particularly birds. We investigated patterns of agonistic support (defined as a third party intervening in an ongoing conflict to attack one of the conflict participants, thus supporting the other) in a group of 13 captive ravens, Corvus corax. We found support for long-term, but not short-term, reciprocation of agonistic support. Ravens were more likely to support individuals who preened them, kin and dominant group members. These results suggest that ravens do not reciprocate on a calculated tit-for-tat basis, but aid individuals from whom reciprocated support would be most useful and those with whom they share a good relationship. Additionally, dyadic levels of agonistic support and consolation (postconflict affiliation from a bystander to the victim) correlated strongly with each other, but we found no evidence to suggest that receiving agonistic support influences the victim's likelihood of receiving support (consolation) after the conflict ends. Our findings are consistent with an emotionally mediated form of reciprocity in ravens and provide additional support for convergent cognitive evolution in birds and mammals.

Reciprocity of agonistic support in ravens

PubMed Central

Fraser, Orlaith N.; Bugnyar, Thomas

2012-01-01

Cooperative behaviour through reciprocation or interchange of valuable services in primates has received considerable attention, especially regarding the timeframe of reciprocation and its ensuing cognitive implications. Much less, however, is known about reciprocity in other animals, particularly birds. We investigated patterns of agonistic support (defined as a third party intervening in an ongoing conflict to attack one of the conflict participants, thus supporting the other) in a group of 13 captive ravens, Corvus corax. We found support for long-term, but not short-term, reciprocation of agonistic support. Ravens were more likely to support individuals who preened them, kin and dominant group members. These results suggest that ravens do not reciprocate on a calculated tit-for-tat basis, but aid individuals from whom reciprocated support would be most useful and those with whom they share a good relationship. Additionally, dyadic levels of agonistic support and consolation (postconflict affiliation from a bystander to the victim) correlated strongly with each other, but we found no evidence to suggest that receiving agonistic support influences the victim’s likelihood of receiving support (consolation) after the conflict ends. Our findings are consistent with an emotionally mediated form of reciprocity in ravens and provide additional support for convergent cognitive evolution in birds and mammals. PMID:22298910

Common and unique responses to dopamine agonist therapy and deep brain stimulation in Parkinson's disease: an H(2)(15)O PET study.

PubMed

Bradberry, Trent J; Metman, Leonard Verhagen; Contreras-Vidal, José L; van den Munckhof, Pepijn; Hosey, Lara A; Thompson, Jennifer L W; Schulz, Geralyn M; Lenz, Fredrick; Pahwa, Rajesh; Lyons, Kelly E; Braun, Allen R

2012-10-01

Dopamine agonist therapy and deep brain stimulation (DBS) of the subthalamic nucleus (STN) are antiparkinsonian treatments that act on a different part of the basal ganglia-thalamocortical motor circuitry, yet produce similar symptomatic improvements. The purpose of this study was to identify common and unique brain network features of these standard treatments. We analyzed images produced by H(2)(15)O positron emission tomography (PET) of patients with Parkinson's disease (PD) at rest. Nine patients were scanned before and after injection of apomorphine, and 11 patients were scanned while bilateral stimulators were off and while they were on. Both treatments produced common deactivations of the neocortical sensorimotor areas, including the supplementary motor area, precentral gyrus, and postcentral gyrus, and in subcortical structures, including the putamen and cerebellum. We observed concomitant activations of the superior parietal lobule and the midbrain in the region of the substantia nigra/STN. We also detected unique, treatment-specific changes with possible motor-related consequences in the basal ganglia, thalamus, neocortical sensorimotor cortex, and posterolateral cerebellum. Unique changes in nonmotor regions may reflect treatment-specific effects on verbal fluency and limbic functions. Many of the common effects of these treatments are consistent with the standard pathophysiologic model of PD. However, the common effects in the cerebellum are not readily explained by the model. Consistent deactivation of the cerebellum is interesting in light of recent reports of synaptic pathways directly connecting the cerebellum and basal ganglia, and may warrant further consideration for incorporation into the model. Published by Elsevier Inc.

Medical and surgical management of advanced Parkinson's disease.

PubMed

Antonini, Angelo; Moro, Elena; Godeiro, Clecio; Reichmann, Heinz

2018-03-23

Advanced Parkinson's disease is characterized by the presence of motor fluctuations, various degree of dyskinesia, and disability with functional impact on activities of daily living and independence. Therapeutic management aims to extend levodopa benefit while minimizing motor complications and includes, in selected cases, the implementation of drug infusion and surgical techniques. In milder forms of motor complications, these can often be controlled with manipulation of levodopa dose and the introduction of supplemental therapies such as catechol-O-methyl transferase inhibitors, monoamine oxidase B inhibitors, and dopamine agonists including apomorphine. Clinical experience and evidence from published studies indicate that when these agents cannot satisfactorily control motor complications, patients should be assessed and considered for device-aided therapies. This review article summarizes some of the newer available therapeutic opportunities such as use of enzyme inhibitors like opicapone and safinamide, adenosine A 2A receptor antagonists, apomorphine and levodopa/carbidopa intestinal gel infusion, deep brain stimulation including the role of closed-loop and adaptive stimulation, and MRI-guided focused ultrasound. © 2018 International Parkinson and Movement Disorder Society. © 2018 International Parkinson and Movement Disorder Society.

Functional map of arrestin binding to phosphorylated opsin, with and without agonist.

PubMed

Peterhans, Christian; Lally, Ciara C M; Ostermaier, Martin K; Sommer, Martha E; Standfuss, Jörg

2016-06-28

Arrestins desensitize G protein-coupled receptors (GPCRs) and act as mediators of signalling. Here we investigated the interactions of arrestin-1 with two functionally distinct forms of the dim-light photoreceptor rhodopsin. Using unbiased scanning mutagenesis we probed the individual contribution of each arrestin residue to the interaction with the phosphorylated apo-receptor (Ops-P) and the agonist-bound form (Meta II-P). Disruption of the polar core or displacement of the C-tail strengthened binding to both receptor forms. In contrast, mutations of phosphate-binding residues (phosphosensors) suggest the phosphorylated receptor C-terminus binds arrestin differently for Meta II-P and Ops-P. Likewise, mutations within the inter-domain interface, variations in the receptor-binding loops and the C-edge of arrestin reveal different binding modes. In summary, our results indicate that arrestin-1 binding to Meta II-P and Ops-P is similarly dependent on arrestin activation, although the complexes formed with these two receptor forms are structurally distinct.

Mechanisms of inverse agonist action at D2 dopamine receptors

PubMed Central

Roberts, David J; Strange, Philip G

2005-01-01

Mechanisms of inverse agonist action at the D2(short) dopamine receptor have been examined. Discrimination of G-protein-coupled and -uncoupled forms of the receptor by inverse agonists was examined in competition ligand-binding studies versus the agonist [3H]NPA at a concentration labelling both G-protein-coupled and -uncoupled receptors. Competition of inverse agonists versus [3H]NPA gave data that were fitted best by a two-binding site model in the absence of GTP but by a one-binding site model in the presence of GTP. Ki values were derived from the competition data for binding of the inverse agonists to G-protein-uncoupled and -coupled receptors. Kcoupled and Kuncoupled were statistically different for the set of compounds tested (ANOVA) but the individual values were different in a post hoc test only for (+)-butaclamol. These observations were supported by simulations of these competition experiments according to the extended ternary complex model. Inverse agonist efficacy of the ligands was assessed from their ability to reduce agonist-independent [35S]GTPγS binding to varying degrees in concentration–response curves. Inverse agonism by (+)-butaclamol and spiperone occurred at higher potency when GDP was added to assays, whereas the potency of (−)-sulpiride was unaffected. These data show that some inverse agonists ((+)-butaclamol, spiperone) achieve inverse agonism by stabilising the uncoupled form of the receptor at the expense of the coupled form. For other compounds tested, we were unable to define the mechanism. PMID:15735658

ApoE4 induces Aβ42, tau, and neuronal pathology in the hippocampus of young targeted replacement apoE4 mice

PubMed Central

2013-01-01

Background Recent findings suggest that the pathological effects of apoE4, the most prevalent genetic risk factor for Alzheimer’s disease (AD), start many years before the onset of the disease and are already detectable at a young age. In the present study we investigated the extent to which such pathological and cognitive impairments also occur in young apoE4 mice. Results This study revealed that the levels of the presynaptic glutamatergic vesicular transporter, VGlut, in the CA3, CA1, and DG hippocampal subfields were lower in hippocampal neurons of young (4-month-old) apoE4-targeted replacement mice than in those of the apoE3 mice. In contrast, the corresponding inhibitory GABAergic nerve terminals and perikarya were not affected by apoE4. This synaptic effect was associated with hyperphosphorylation of tau in these neurons. In addition, apoE4 increased the accumulation of neuronal Aβ42 and induced mitochondrial changes, both of which were specifically pronounced in CA3 neurons. Spatial navigation behavioral studies revealed that these hippocampal pathological effects of apoE4 are associated with corresponding behavioral impairments. Time-course studies revealed that the effects of apoE4 on tau hyperphosphorylation and the mitochondria were already apparent at the age of 1 month and that the apoE4-driven accumulation of neuronal Aβ and reduced VGlut levels evolve later and are apparent at the age of 2–4 months. Furthermore, the levels of tau phosphorylation decrease in apoE3 mice and increase in apoE4 mice between 1 and 4 months, whereas the levels of Aβ42 decrease in apoE3 mice and are not affected in apoE4 mice over the same time period. Conclusions These findings show that apoE4 stimulates the accumulation of Aβ42 and hyperphosphorylated tau and reduces the levels of VGlut in hippocampal neurons of young apoE4-targeted replacement mice and that these neurochemical effects are associated with cognitive impairments. This model is not associated with

ApoE4 induces Aβ42, tau, and neuronal pathology in the hippocampus of young targeted replacement apoE4 mice.

PubMed

Liraz, Ori; Boehm-Cagan, Anat; Michaelson, Daniel M

2013-05-17

Recent findings suggest that the pathological effects of apoE4, the most prevalent genetic risk factor for Alzheimer's disease (AD), start many years before the onset of the disease and are already detectable at a young age. In the present study we investigated the extent to which such pathological and cognitive impairments also occur in young apoE4 mice. This study revealed that the levels of the presynaptic glutamatergic vesicular transporter, VGlut, in the CA3, CA1, and DG hippocampal subfields were lower in hippocampal neurons of young (4-month-old) apoE4-targeted replacement mice than in those of the apoE3 mice. In contrast, the corresponding inhibitory GABAergic nerve terminals and perikarya were not affected by apoE4.This synaptic effect was associated with hyperphosphorylation of tau in these neurons. In addition, apoE4 increased the accumulation of neuronal Aβ42 and induced mitochondrial changes, both of which were specifically pronounced in CA3 neurons. Spatial navigation behavioral studies revealed that these hippocampal pathological effects of apoE4 are associated with corresponding behavioral impairments. Time-course studies revealed that the effects of apoE4 on tau hyperphosphorylation and the mitochondria were already apparent at the age of 1 month and that the apoE4-driven accumulation of neuronal Aβ and reduced VGlut levels evolve later and are apparent at the age of 2-4 months. Furthermore, the levels of tau phosphorylation decrease in apoE3 mice and increase in apoE4 mice between 1 and 4 months, whereas the levels of Aβ42 decrease in apoE3 mice and are not affected in apoE4 mice over the same time period. These findings show that apoE4 stimulates the accumulation of Aβ42 and hyperphosphorylated tau and reduces the levels of VGlut in hippocampal neurons of young apoE4-targeted replacement mice and that these neurochemical effects are associated with cognitive impairments. This model is not associated with hypothesis-driven mechanistic

Activation of single heteromeric GABAA receptor ion channels by full and partial agonists

PubMed Central

Mortensen, Martin; Kristiansen, Uffe; Ebert, Bjarke; Frølund, Bente; Krogsgaard-Larsen, Povl; Smart, Trevor G

2004-01-01

The linkage between agonist binding and the activation of a GABAA receptor ion channel is yet to be resolved. This aspect was examined on human recombinant α1β2γ2S GABAA receptors expressed in human embryonic kidney cells using the following series of receptor agonists: GABA, isoguvacine, 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), isonipecotic acid, piperidine-4-sulphonic acid (P4S), imidazole-4-acetic acid (IAA), 5-(4-piperidyl)-3-isothiazolol (thio-4-PIOL) and 5-(4-piperidyl)-3-isoxazolol (4-PIOL). Whole-cell concentration–response curves enabled the agonists to be categorized into four classes based upon their maximum responses. Single channel analyses revealed that the channel conductance of 25–27 pS was unaffected by the agonists. However, two open states were resolved from the open period distributions with mean open times reduced 5-fold by the weakest partial agonists. Using saturating agonist concentrations, estimates of the channel shutting rate, α, ranged from 200 to 600 s−1. The shut period distributions were described by three or four components and for the weakest partial agonists, the interburst shut periods increased whilst the mean burst durations and longest burst lengths were reduced relative to the full agonists. From the burst analyses, the opening rates for channel activation, β, and the total dissociation rates, k−1, for the agonists leaving the receptor were estimated. The agonist efficacies were larger for the full agonists (E ∼7−9) compared to the weak partial agonists (∼0.4–0.6). Overall, changes in agonist efficacy largely determined the different agonist profiles with contributions from the agonist affinities and the degree of receptor desensitization. From this we conclude that GABAA receptor activation does not occur in a switch-like manner since the agonist recognition sites are flexible, accommodating diverse agonist structures which differentially influence the opening and shutting rates of the ion

Ghrelin and motilin receptor agonists: time to introduce bias into drug design.

PubMed

Sanger, G J

2014-02-01

Ghrelin and motilin receptor agonists increase gastric motility and are attractive drug targets. However, 14 years after the receptors were described (18-24 years since ligands became available) the inactivity of the ghrelin agonist TZP-102 in patients with gastroparesis joins the list of unsuccessful motilin agonists. Fundamental questions must be asked. Pustovit et al., have now shown that the ghrelin agonist ulimorelin evokes prolonged increases in rat colorectal propulsion yet responses to other ghrelin agonists fade. Similarly, different motilin agonists induce short- or long-lasting effects in a cell-dependent manner. Together, these and other data create the hypothesis that the receptors can be induced to preferentially signal ('biased agonism') via particular pathways to evoke different responses with therapeutic advantages/disadvantages. Biased agonism has been demonstrated for ghrelin. Are motilin agonists which cause long-lasting facilitation of human stomach cholinergic function (compared with motilin) biased agonists (e.g., camicinal, under development for patients with gastric hypo-motility)? For ghrelin, additional complications exist because the therapeutic aims/mechanisms of action are uncertain, making it difficult to select the best (biased) agonist. Will ghrelin agonists be useful treatments of nausea and/or as suggested by Pustovit et al., chronic constipation? How does ghrelin increase gastric motility? As gastroparesis symptoms poorly correlate with delayed gastric emptying (yet gastro-prokinetic drugs can provide relief: e.g., low-dose erythromycin), would low doses of ghrelin and motilin agonists relieve symptoms simply by restoring neuromuscular rhythm? These questions on design and functions need addressing if ghrelin and motilin agonists are to reach patients as drugs. © 2014 John Wiley & Sons Ltd.

Reverse Induced Fit-Driven MAS-Downstream Transduction: Looking for Metabotropic Agonists.

PubMed

Pernomian, Larissa; Gomes, Mayara S; de Paula da Silva, Carlos H Tomich; Rosa, Joaquin M C

2017-01-01

Protective effects of MAS activation have spurred clinical interests in developing MAS agonists. However, current bases that drive this process preclude that physiological concentrations of peptide MAS agonists induce an atypical signaling that does not reach the metabotropic efficacy of constitutive activation. Canonical activation of MAS-coupled G proteins is only achieved by supraphysiological concentrations of peptide MAS agonists or physiological concentrations of chemically modified analogues. These pleiotropic differences are because of two overlapped binding domains: one non-metabotropic site that recognizes peptide agonists and one metabotropic domain that recognizes modified analogues. It is feasible that supraphysiological concentrations of peptide MAS agonists undergo to chemical modifications required for binding to metabotropic domain. Receptor oligomerization enhances pharmacological parameters coupled to metabotropic signaling. The formation of receptor-signalosome complex makes the transduction of agonists more adaptive. Considering the recent identification of MAS-signalosome, we aimed to postulate the reverse induced fit hypothesis in which MAS-signalosome would trigger chemical modifications required for agonists bind to MAS metabotropic domain. Here we cover rational perspectives for developing novel metabotropic MAS agonists in the view of the reverse induced-fit hypothesis. Predicting a 3D model of MAS metabotropic domain may guide the screening of chemical modifications required for metabotropic efficacy. Pharmacophore-based virtual screening would select potential metabotropic MAS agonists from virtual libraries from human proteome. Rational perspectives that consider reverse induced fit hypothesis during MAS activation for developing metabotropic MAS agonists represents the best approach in providing MAS ligands with constitutive efficacy at physiological concentrations. Copyright© Bentham Science Publishers; For any queries, please email

Trial Watch: Toll-like receptor agonists for cancer therapy.

PubMed

Vacchelli, Erika; Eggermont, Alexander; Sautès-Fridman, Catherine; Galon, Jérôme; Zitvogel, Laurence; Kroemer, Guido; Galluzzi, Lorenzo

2013-08-01

Toll-like receptors (TLRs) have long been known for their ability to initiate innate immune responses upon exposure to conserved microbial components such as lipopolysaccharide (LPS) and double-stranded RNA. More recently, this family of pattern recognition receptors has been attributed a critical role in the elicitation of anticancer immune responses, raising interest in the development of immunochemotherapeutic regimens based on natural or synthetic TLR agonists. In spite of such an intense wave of preclinical and clinical investigation, only three TLR agonists are currently licensed by FDA for use in cancer patients: bacillus Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis that operates as a mixed TLR2/TLR4 agonist; monophosphoryl lipid A (MPL), a derivative of Salmonella minnesota that functions as a potent agonist of TLR4; and imiquimod, a synthetic imidazoquinoline that activates TLR7. One year ago, in the August and September issues of OncoImmunology , we described the main biological features of TLRs and discussed the progress of clinical studies evaluating the safety and therapeutic potential of TLR agonists in cancer patients. Here, we summarize the latest developments in this exciting area of research, focusing on preclinical studies that have been published during the last 13 mo and clinical trials launched in the same period to investigate the antineoplastic activity of TLR agonists.

Antipsychotic-like vs cataleptogenic actions in mice of novel antipsychotics having D2 antagonist and 5-HT1A agonist properties.

PubMed

Bardin, Laurent; Kleven, Mark S; Barret-Grévoz, Catherine; Depoortère, Ronan; Newman-Tancredi, Adrian

2006-09-01

A new generation of proven or potential antipsychotics, including aripiprazole, bifeprunox, SSR181507 and SLV313, exhibit agonist actions at serotonin 5-HT1A receptors, but little comparative data are available on their pharmacological profiles. Here, we compared in mice the in vivo antipsychotic-like vs cataleptogenic activities of these compounds with those of drugs that exhibit little interaction at 5-HT1A receptors, such as haloperidol, olanzapine and risperidone. All the drugs dose-dependently reduced apomorphine-induced climbing or sniffing and, with the exception of ziprasidone, produced complete suppression of these responses. In the bar catalepsy test, when administered alone, haloperidol, olanzapine and risperidone produced marked catalepsy, whereas, at doses up to 40 mg/kg, aripiprazole, SLV313, SSR181507, and sarizotan produced little or no catalepsy. The latter compounds, therefore, displayed a large separation between doses with 'antipsychotic-like' and those with cataleptogenic actions. When 5-HT1A receptors were blocked by pretreatment with WAY100635 (2.5 mg/kg, s.c.), cataleptogenic properties of SSR181507 and sarizotan were unmasked, and the catalepsy induced by bifeprunox was enhanced. In the case of aripiprazole and SLV313, although WAY100635 produced upward shifts in their dose-response, the magnitude of catalepsy appeared to reach an asymptotic plateau, suggesting that other mechanisms may be involved in their low cataleptogenic liability. The present data confirm that 5-HT1A receptor activation reduces or even completely prevents the cataleptogenic potential of novel antipsychotic agents. Further, they indicate that the balance of affinity and/or efficacy between D2 and 5-HT1A receptors profoundly influences their pharmacological activities, and will likely impact their therapeutic profiles.

Apolipoprotein E3 (ApoE3) but Not ApoE4 Protects against Synaptic Loss through Increased Expression of Protein Kinase Cϵ

PubMed Central

Sen, Abhik; Alkon, Daniel L.; Nelson, Thomas J.

2012-01-01

Synaptic loss is the earliest pathological change in Alzheimer disease (AD) and is the pathological change most directly correlated with the degree of dementia. ApoE4 is the major genetic risk factor for the age-dependent form of AD, which accounts for 95% of cases. Here we show that in synaptic networks formed from primary hippocampal neurons in culture, apoE3, but not apoE4, prevents the loss of synaptic networks produced by amyloid β oligomers (amylospheroids). Specific activators of PKCϵ, such as 8-(2-(2-pentyl-cyclopropylmethyl)-cyclopropyl)-octanoic acid methyl ester and bryostatin 1, protected against synaptic loss by amylospheroids, whereas PKCϵ inhibitors blocked this synaptic protection and also blocked the protection by apoE3. Blocking LRP1, an apoE receptor on the neuronal membrane, also blocked the protection by apoE. ApoE3, but not apoE4, induced the synthesis of PKCϵ mRNA and expression of the PKCϵ protein. Amyloid β specifically blocked the expression of PKCϵ but had no effect on other isoforms. These results suggest that protection against synaptic loss by apoE is mediated by a novel intracellular PKCϵ pathway. This apoE pathway may account for much of the protective effect of apoE and reduced risk for the age-dependent form of AD. This finding supports the potential efficacy of newly developed therapeutics for AD. PMID:22427674

Cancer immunotherapy: activating innate and adaptive immunity through CD40 agonists

PubMed Central

Beatty, Gregory L.; Li, Yan; Long, Kristen B.

2017-01-01

INTRODUCTION CD40 is a promising therapeutic target for cancer immunotherapy. In patients with advanced solid malignancies, CD40 agonists have demonstrated some anti-tumor activity and a manageable toxicity profile. A 2nd generation of CD40 agonists has now been designed with optimized Fc receptor (FcR) binding based on preclinical evidence suggesting a critical role for FcR engagement in defining the potency of CD40 agonists in vivo. AREAS COVERED We provide a comprehensive review using PubMed and Google Patent databases on the current clinical status of CD40 agonists, strategies for applying CD40 agonists in cancer therapy, and the preclinical data that supports and is guiding the future development of CD40 agonists. EXPERT COMMENTARY There is a wealth of preclinical data that provide rationale on several distinct approaches for using CD40 agonists in cancer immunotherapy. This data illustrates the need to strategically combine CD40 agonists with other clinically active treatment regimens in order to realize the full potential of activating CD40 in vivo. Thus, critical to the success of this class of immune-oncology drugs, which have the potential to restore both innate and adaptive immunosurveillance, will be the identification of biomarkers for monitoring and predicting responses as well as informing mechanisms of treatment resistance. PMID:27927088

Identification of M-CSF agonists and antagonists

DOEpatents

Pandit, Jayvardhan [Mystic, CT; Jancarik, Jarmila [Walnut Creek, CA; Kim, Sung-Hou [Moraga, CA; Koths, Kirston [El Cerrito, CA; Halenbeck, Robert [San Rafael, CA; Fear, Anna Lisa [Oakland, CA; Taylor, Eric [Oakland, CA; Yamamoto, Ralph [Martinez, CA; Bohm, Andrew [Armonk, NY

2000-02-15

The present invention is directed to methods for crystallizing macrophage colony stimulating factor. The present invention is also directed to methods for designing and producing M-CSF agonists and antagonists using information derived from the crystallographic structure of M-CSF. The invention is also directed to methods for screening M-CSF agonists and antagonists. In addition, the present invention is directed to an isolated, purified, soluble and functional M-CSF receptor.

Synthetic RORγt Agonists Enhance Protective Immunity

PubMed Central

Chang, Mi Ra; Dharmarajan, Venkatasubramanian; Doebelin, Christelle; Garcia-Ordonez, Ruben D.; Novick, Scott J.; Kuruvilla, Dana S.; Kamenecka, Theodore M.; Griffin, Patrick R.

2016-01-01

The T cell specific RORγ isoform RORγt has been shown to be the key lineage-defining transcription factor to initiate the differentiation program of TH17 and Tc17 cells, cells that have demonstrated anti-tumor efficacy. RORγt controls gene networks that enhance immunity including increased IL17 production and decreased immune suppression. Both synthetic and putative endogenous agonists of RORγt have been shown to increase the basal activity of RORγt enhancing TH17 cell proliferation. Here we show that activation of RORγt using synthetic agonists drives proliferation of TH17 cells while decreasing levels of the immune checkpoint protein PD-1, a mechanism that should enhance anti-tumor immunity while blunting tumor associated adaptive immune resistance. Interestingly, putative endogenous agonists drive proliferation of TH17 cells but do not repress PD-1. These findings suggest that synthetic agonists of RORγt should activate TC17/TH17 cells (with concomitant reduction in the Tregs population), repress PD-1, and produce IL17 in situ (a factor associated with good prognosis in cancer). Enhanced immunity and blockage of immune checkpoints has transformed cancer treatment, thus such a molecule would provide a unique approach for the treatment of cancer. PMID:26785144

Magnesium ions and opioid agonists in vincristine-induced neuropathy.

PubMed

Bujalska, Magdalena; Makulska-Nowak, Helena; Gumułka, Stanisław W

2009-01-01

Neuropathic pain is difficult to treat. Classic analgesics (i.e., opioid receptor agonists) usually possess low activity. Therefore other agents such as antidepressants, anticonvulsants, and corticosteroids are used. It is commonly known that NMDA antagonists increase analgesic activity of opioids. Unfortunately, clinical use of NMDA antagonists is limited because of the relatively frequent occurrence of adverse effects e.g., memory impairment, psychomimetic effects, ataxia and motor in-coordination. Magnesium ions (Mg(2+)) are NMDA receptor blockers in physiological conditions. Therefore, in this study the effect of opioid receptor agonists and the influence of Mg(2+) on the action of opioid agonists in vincristine-induced hyperalgesia were examined. Opioid agonists such as morphine (5 mg/kg, ip), and fentanyl (0.0625 mg/kg, ip), as well as the partial agonist buprenorphine (0.075 mg/kg, ip) administered alone on 5 consecutives days did not modify the hyperalgesia in vincristine rats. In contrast, pretreatment with a low dose of magnesium sulfate (30 mg/kg, ip) resulted in a progressive increase of the analgesic action of all three investigated opioids. After discontinuation of drug administration, the effect persisted for several days.

TLR9 agonist protects mice from radiation-induced gastrointestinal syndrome.

PubMed

Saha, Subhrajit; Bhanja, Payel; Liu, Laibin; Alfieri, Alan A; Yu, Dong; Kandimalla, Ekambar R; Agrawal, Sudhir; Guha, Chandan

2012-01-01

Radiation-induced gastrointestinal syndrome (RIGS) is due to the clonogenic loss of crypt cells and villi depopulation, resulting in disruption of mucosal barrier, bacterial invasion, inflammation and sepsis. Intestinal macrophages could recognize invading bacterial DNA via TLR9 receptors and transmit regenerative signals to the neighboring crypt. We therefore investigated whether systemic administration of designer TLR9 agonist could ameliorate RIGS by activating TLR9. Male C57Bl6 mice were distributed in four experimental cohorts, whole body irradiation (WBI) (8.4-10.4 Gy), TLR9 agonist (1 mg/kg s.c.), 1 h pre- or post-WBI and TLR9 agonist+WBI+iMyd88 (pretreatment with inhibitory peptide against Myd88). Animals were observed for survival and intestine was harvested for histological analysis. BALB/c mice with CT26 colon tumors in abdominal wall were irradiated with 14 Gy single dose of whole abdominal irradiation (AIR) for tumor growth study. Mice receiving pre-WBI TLR9 agonist demonstrated improvement of survival after 10.4 Gy (p<0.03), 9.4 Gy (p<0.008) and 8.4 Gy (p<0.002) of WBI, compared to untreated or iMyd88-treated controls. Post-WBI TLR9 agonist mitigates up to 8.4 Gy WBI (p<0.01). Histological analysis and xylose absorption test demonstrated significant structural and functional restitution of the intestine in WBI+TLR9 agonist cohorts. Although, AIR reduced tumor growth, all animals died within 12 days from RIGS. TLR9 agonist improved the survival of mice beyond 28 days post-AIR (p<0.008) with significant reduction of tumor growth (p<0.0001). TLR9 agonist treatment could serve both as a prophylactic or mitigating agent against acute radiation syndrome and also as an adjuvant therapy to increase the therapeutic ratio of abdominal Radiation Therapy for Gastro Intestinal malignancies.

TOXICITY OF AHR AGONISTS TO FISH EARLY LIFE STAGES

EPA Science Inventory

Fish early life stages are exceptionally sensitive to the lethal toxicity of chemicals that act as arylhydrocarbon receptor (AhR) agonists. Toxicity characterizations based on 2,3,7,8-tetrachlorodibenzo-p-dioxin, generally the most potent AhR agonist, support the toxicity equiva...

Dual Agonist Surrobody Simultaneously Activates Death Receptors DR4 and DR5 to Induce Cancer Cell Death.

PubMed

Milutinovic, Snezana; Kashyap, Arun K; Yanagi, Teruki; Wimer, Carina; Zhou, Sihong; O'Neil, Ryann; Kurtzman, Aaron L; Faynboym, Alexsandr; Xu, Li; Hannum, Charles H; Diaz, Paul W; Matsuzawa, Shu-ichi; Horowitz, Michael; Horowitz, Lawrence; Bhatt, Ramesh R; Reed, John C

2016-01-01

Death receptors of the TNF family are found on the surface of most cancer cells and their activation typically kills cancer cells through the stimulation of the extrinsic apoptotic pathway. The endogenous ligand for death receptors 4 and 5 (DR4 and DR5) is TNF-related apoptosis-inducing ligand, TRAIL (Apo2L). As most untransformed cells are not susceptible to TRAIL-induced apoptosis, death receptor activators have emerged as promising cancer therapeutic agents. One strategy to stimulate death receptors in cancer patients is to use soluble human recombinant TRAIL protein, but this agent has limitations of a short half-life and decoy receptor sequestration. Another strategy that attempted to evade decoy receptor sequestration and to provide improved pharmacokinetic properties was to generate DR4 or DR5 agonist antibodies. The resulting monoclonal agonist antibodies overcame the limitations of short half-life and avoided decoy receptor sequestration, but are limited by activating only one of the two death receptors. Here, we describe a DR4 and DR5 dual agonist produced using Surrobody technology that activates both DR4 and DR5 to induce apoptotic death of cancer cells in vitro and in vivo and also avoids decoy receptor sequestration. This fully human anti-DR4/DR5 Surrobody displays superior potency to DR4- and DR5-specific antibodies, even when combined with TRAIL-sensitizing proapoptotic agents. Moreover, cancer cells were less likely to acquire resistance to Surrobody than either anti-DR4 or anti-DR5 monospecific antibodies. Taken together, Surrobody shows promising preclinical proapoptotic activity against cancer cells, meriting further exploration of its potential as a novel cancer therapeutic agent. ©2015 American Association for Cancer Research.

Dual agonist Surrobody™ simultaneously activates death receptors DR4 and DR5 to induce cancer cell death

PubMed Central

Milutinovic, Snezana; Kashyap, Arun K.; Yanagi, Teruki; Wimer, Carina; Zhou, Sihong; O' Neil, Ryann; Kurtzman, Aaron L.; Faynboym, Alexsandr; Xu, Li; Hannum, Charles H.; Diaz, Paul W.; Matsuzawa, Shu-ichi; Horowitz, Michael; Horowitz, Lawrence; Bhatt, Ramesh R.; Reed, John C.

2015-01-01

Death receptors of the Tumor Necrosis Factor (TNF) family are found on surface of most cancer cells and their activation typically kills cancer cells through the stimulation of the extrinsic apoptotic pathway. The endogenous ligand for death receptors-4 and -5 (DR4 and DR5) is Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand, TRAIL (Apo2L). Since most untransformed cells are not susceptible to TRAIL-induced apoptosis, death receptor activators have emerged as promising cancer therapeutic agents. One strategy to stimulate death receptors in cancer patients is to use soluble human recombinant TRAIL protein, but this agent has limitations of a short half-life and decoy receptor sequestration. Another strategy that attempted to evade decoy receptor sequestration and to provide improved pharmacokinetic properties was to generate DR4 or DR5 agonist antibodies. The resulting monoclonal agonist antibodies overcame the limitations of short half-life and avoided decoy receptor sequestration, but are limited by activating only one of the two death receptors. Here, we describe a DR4 and DR5 dual agonist produced using Surrobody™ technology that activates both DR4 and DR5 to induce apoptotic death of cancer cells in vitro and in vivo and also avoids decoy receptor sequestration. This fully human anti-DR4/DR5 Surrobody displays superior potency to DR4- and DR5-specific antibodies, even when combined with TRAIL-sensitizing pro-apoptotic agents. Moreover, cancer cells were less likely to acquire resistance to Surrobody than either anti-DR4 or anti-DR5 mono-specific antibodies. Taken together, Surrobody shows promising preclinical pro-apoptotic activity against cancer cells, meriting further exploration of its potential as a novel cancer therapeutic agent. PMID:26516157

Genetic Restoration of Plasma ApoE Improves Cognition and Partially Restores Synaptic Defects in ApoE-Deficient Mice

PubMed Central

Wong, Wen Mai; Durakoglugil, Murat S.; Wasser, Catherine R.; Jiang, Shan; Xian, Xunde

2016-01-01

Alzheimer's disease (AD) is the most common form of dementia in individuals over the age of 65 years. The most prevalent genetic risk factor for AD is the ε4 allele of apolipoprotein E (ApoE4), and novel AD treatments that target ApoE are being considered. One unresolved question in ApoE biology is whether ApoE is necessary for healthy brain function. ApoE knock-out (KO) mice have synaptic loss and cognitive dysfunction; however, these findings are complicated by the fact that ApoE knock-out mice have highly elevated plasma lipid levels, which may independently affect brain function. To bypass the effect of ApoE loss on plasma lipids, we generated a novel mouse model that expresses ApoE normally in peripheral tissues, but has severely reduced ApoE in the brain, allowing us to study brain ApoE loss in the context of a normal plasma lipid profile. We found that these brain ApoE knock-out (bEKO) mice had synaptic loss and dysfunction similar to that of ApoE KO mice; however, the bEKO mice did not have the learning and memory impairment observed in ApoE KO mice. Moreover, we found that the memory deficit in the ApoE KO mice was specific to female mice and was fully rescued in female bEKO mice. Furthermore, while the AMPA/NMDA ratio was reduced in ApoE KO mice, it was unchanged in bEKO mice compared with controls. These findings suggest that plasma lipid levels can influence cognition and synaptic function independent of ApoE expression in the brain. SIGNIFICANCE STATEMENT One proposed treatment strategy for Alzheimer's disease (AD) is the reduction of ApoE, whose ε4 isoform is the most common genetic risk factor for the disease. A major concern of this strategy is that an animal model of ApoE deficiency, the ApoE knock-out (KO) mouse, has reduced synapses and cognitive impairment; however, these mice also develop dyslipidemia and severe atherosclerosis. Here, we have shown that genetic restoration of plasma ApoE to wild-type levels normalizes plasma lipids in ApoE KO

Electrophysiological Perspectives on the Therapeutic Use of Nicotinic Acetylcholine Receptor Partial AgonistsS⃞

PubMed Central

Trocmé-Thibierge, Caryn; Guendisch, Daniela; Al Rubaiy, Shehd Abdullah Abbas; Bloom, Stephen A.

2011-01-01

Partial agonist therapies rely variously on two hypotheses: the partial agonists have their effects through chronic low-level receptor activation or the partial agonists work by decreasing the effects of endogenous or exogenous full agonists. The relative significance of these activities probably depends on whether acute or chronic effects are considered. We studied nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus laevis oocytes to test a model for the acute interactions between acetylcholine (ACh) and weak partial agonists. Data were best-fit to a basic competition model that included an additional factor for noncompetitive inhibition. Partial agonist effects were compared with the nAChR antagonist bupropion in prolonged bath application experiments that were designed to mimic prolonged drug exposure typical of therapeutic drug delivery. A primary effect of prolonged application of nicotine was to decrease the response of all nAChR subtypes to acute applications of ACh. In addition, nicotine, cytisine, and varenicline produced detectable steady-state activation of α4β2* [(α4)2(β2)3, (α4)3(β2)2, and (α4)2(β2)2α5)] receptor subtypes that was not seen with other test compounds. Partial agonists produced no detectable steady-state activation of α7 nAChR, but seemed to show small potentiation of ACh-evoked responses; however, “run-up” of α7 ACh responses was also sometimes observed under control conditions. Potential off-target effects of the partial agonists therefore included the modulation of α7 responses by α4β2 partial agonists and decreases in α4β2* responses by α7-selective agonists. These data indicate the dual effects expected for α4β2* partial agonists and provide models and insights for utility of partial agonists in therapeutic development. PMID:21285282

Agonist-Specific Recruitment of Arrestin Isoforms Differentially Modify Delta Opioid Receptor Function

PubMed Central

Perroy, Julie; Walwyn, Wendy M.; Smith, Monique L.; Vicente-Sanchez, Ana; Segura, Laura; Bana, Alia; Kieffer, Brigitte L.; Evans, Christopher J.

2016-01-01

Ligand-specific recruitment of arrestins facilitates functional selectivity of G-protein-coupled receptor signaling. Here, we describe agonist-selective recruitment of different arrestin isoforms to the delta opioid receptor in mice. A high-internalizing delta opioid receptor agonist (SNC80) preferentially recruited arrestin 2 and, in arrestin 2 knock-outs (KOs), we observed a significant increase in the potency of SNC80 to inhibit mechanical hyperalgesia and decreased acute tolerance. In contrast, the low-internalizing delta agonists (ARM390, JNJ20788560) preferentially recruited arrestin 3 with unaltered behavioral effects in arrestin 2 KOs. Surprisingly, arrestin 3 KO revealed an acute tolerance to these low-internalizing agonists, an effect never observed in wild-type animals. Furthermore, we examined delta opioid receptor–Ca2+ channel coupling in dorsal root ganglia desensitized by ARM390 and the rate of resensitization was correspondingly decreased in arrestin 3 KOs. Live-cell imaging in HEK293 cells revealed that delta opioid receptors are in pre-engaged complexes with arrestin 3 at the cell membrane and that ARM390 strengthens this membrane interaction. The disruption of these complexes in arrestin 3 KOs likely accounts for the altered responses to low-internalizing agonists. Together, our results show agonist-selective recruitment of arrestin isoforms and reveal a novel endogenous role of arrestin 3 as a facilitator of resensitization and an inhibitor of tolerance mechanisms. SIGNIFICANCE STATEMENT Agonists that bind to the same receptor can produce highly distinct signaling events and arrestins are a major mediator of this ligand bias. Here, we demonstrate that delta opioid receptor agonists differentially recruit arrestin isoforms. We found that the high-internalizing agonist SNC80 preferentially recruits arrestin 2 and knock-out (KO) of this protein results in increased efficacy of SNC80. In contrast, low-internalizing agonists (ARM390 and JNJ20788560

Differential effects of AMPK agonists on cell growth and metabolism

PubMed Central

Vincent, Emma E.; Coelho, Paula P.; Blagih, Julianna; Griss, Takla; Viollet, Benoit; Jones, Russell G.

2016-01-01

As a sensor of cellular energy status, the AMP-activated protein kinase (AMPK) is believed to act in opposition to the metabolic phenotypes favored by proliferating tumor cells. Consequently, compounds known to activate AMPK have been proposed as cancer therapeutics. However, the extent to which the anti-neoplastic properties of these agonists are mediated by AMPK is unclear. Here we examined the AMPK-dependence of six commonly used AMPK agonists (metformin, phenformin, AICAR, 2DG, salicylate and A-769662) and their influence on cellular processes often deregulated in tumor cells. We demonstrate that the majority of these agonists display AMPK-independent effects on cell proliferation and metabolism with only the synthetic activator, A-769662, exerting AMPK-dependent effects on these processes. We find that A-769662 promotes an AMPK-dependent increase in mitochondrial spare respiratory capacity (SRC). Finally, contrary to the view of AMPK activity being tumor suppressive, we find A-769662 confers a selective proliferative advantage to tumor cells growing under nutrient deprivation. Our results indicate that many of the anti-growth properties of these agonists cannot be attributed to AMPK activity in cells, and thus any observed effects using these agonists should be confirmed using AMPK-deficient cells. Ultimately, our data urge caution, not only regarding the type of AMPK agonist proposed for cancer treatment, but also the context in which they are used. PMID:25241895

Plasmalogen modulation attenuates atherosclerosis in ApoE- and ApoE/GPx1-deficient mice.

PubMed

Rasmiena, Aliki A; Barlow, Christopher K; Stefanovic, Nada; Huynh, Kevin; Tan, Ricardo; Sharma, Arpeeta; Tull, Dedreia; de Haan, Judy B; Meikle, Peter J

2015-12-01

We previously reported a negative association of circulating plasmalogens (phospholipids with proposed atheroprotective properties) with coronary artery disease. Plasmalogen modulation was previously demonstrated in animals but its effect on atherosclerosis was unknown. We assessed the effect of plasmalogen enrichment on atherosclerosis of murine models with differing levels of oxidative stress. Six-week old ApoE- and ApoE/glutathione peroxidase-1 (GPx1)-deficient mice were fed a high-fat diet with/without 2% batyl alcohol (precursor to plasmalogen synthesis) for 12 weeks. Mass spectrometry analysis of lipids showed that batyl alcohol supplementation to ApoE- and ApoE/GPx1-deficient mice increased the total plasmalogen levels in both plasma and heart. Oxidation of plasmalogen in the treated mice was evident from increased level of plasmalogen oxidative by-product, sn-2 lysophospholipids. Atherosclerotic plaque in the aorta was reduced by 70% (P = 5.69E-07) and 69% (P = 2.00E-04) in treated ApoE- and ApoE/GPx1-deficient mice, respectively. A 40% reduction in plaque (P = 7.74E-03) was also seen in the aortic sinus of only the treated ApoE/GPx1-deficient mice. Only the treated ApoE/GPx1-deficient mice showed a decrease in VCAM-1 staining (-28%, P = 2.43E-02) in the aortic sinus and nitrotyrosine staining (-78%, P = 5.11E-06) in the aorta. Plasmalogen enrichment via batyl alcohol supplementation attenuated atherosclerosis in ApoE- and ApoE/GPx1-deficient mice, with a greater effect in the latter group. Plasmalogen enrichment may represent a viable therapeutic strategy to prevent atherosclerosis and reduce cardiovascular disease risk, particularly under conditions of elevated oxidative stress and inflammation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Lack of cocaine-like discriminative-stimulus effects of σ-receptor agonists in rats.

PubMed

Hiranita, Takato; Soto, Paul L; Tanda, Gianluigi; Katz, Jonathan L

2011-09-01

Previous studies demonstrated the effectiveness of selective σ-receptor (σR) agonists [1,3-di-o-tolylguanidine (DTG), PRE-084] as reinforcers in rats trained to self-administer cocaine. Similar to cocaine, these drugs increased nucleus accumbens shell dopamine levels, and effects of DTG, but not PRE-084, on dopamine seemed to be mediated by σRs. In addition, σR antagonists blocked self-administration of σR agonists, but were inactive against reinforcing and neurochemical effects of cocaine. Thus, pharmacologically distinct mechanisms likely underlie the reinforcing and neurochemical effects of σR agonists and cocaine. This study further examined the cocaine-like effects of σR agonists in rats trained to discriminate injections of cocaine from saline to assess the similarity of their subjective effects. Standard dopamine-uptake inhibitors (WIN 35,428, methylphenidate), but neither σR agonist (PRE-084, DTG), produced full cocaine-like discriminative-stimulus effects. The lack of effects of σR agonists was obtained regardless of route of administration (intraperitoneal, subcutaneous, or intravenous) or pretreatment time (5 or 30 min before sessions). The present results demonstrate differences in the discriminative-stimulus effects of cocaine and selective σR agonists, indicating that an overlap of subjective effects is not necessary for σR agonist self-administration. The previously found differences in neurochemical effects of cocaine and σR agonists may contribute to their different subjective effects.

Lack of Cocaine-Like Discriminative-Stimulus Effects of σ Receptor Agonists in Rats

PubMed Central

Hiranita, Takato; Soto, Paul L.; Tanda, Gianluigi; Katz, Jonathan L.

2013-01-01

Previous studies demonstrated effectiveness of selective sigma-receptor (σR) agonists (DTG, PRE-084) as reinforcers in rats trained to self-administer cocaine. Like cocaine, these drugs increased nucleus accumbens shell dopamine levels, and effects of DTG, but not PRE-084, on dopamine appeared to be mediated by σRs. Additionally, σR antagonists blocked self-administration of σR agonists, but were inactive against reinforcing and neurochemical effects of cocaine. Thus pharmacologically distinct mechanisms likely underlie the reinforcing and neurochemical effects of σR agonists and cocaine. The present study further examined the cocaine-like effects of σR agonists in rats trained to discriminate injections of cocaine from saline to assess the similarity of their subjective effects. Standard dopamine-uptake inhibitors (WIN 35,428, methylphenidate), but neither σR agonist (PRE-084, DTG) produced full cocaine-like discriminative-stimulus effects. The lack of effects of σR agonists was obtained regardless of route of administration (i.p., s.c. or i.v.) or pretreatment time (5- or 30-min before sessions). The present results demonstrate differences in the discriminative-stimulus effects of cocaine and selective σR agonists, indicating that an overlap of subjective effects is not necessary for σR agonist self-administration. The previously found differences in neurochemical effects of cocaine and σR agonists may contribute to their different subjective effects. PMID:21808192

Pharmacological characterization of the new histamine H4 receptor agonist VUF 8430

PubMed Central

Lim, Herman D; Adami, Maristella; Guaita, Elena; Werfel, Thomas; Smits, Rogier A; de Esch, Iwan JP; Bakker, Remko A; Gutzmer, Ralf; Coruzzi, Gabriella; Leurs, Rob

2009-01-01

Background and purpose: We compare the pharmacological profiles of a new histamine H4 receptor agonist 2-(2-guanidinoethyl)isothiourea (VUF 8430) with that of a previously described H4 receptor agonist, 4-methylhistamine. Experimental approach: Radioligand binding and functional assays were performed using histamine H4 receptors expressed in mammalian cell lines. Compounds were also evaluated ex vivo in monocyte-derived dendritic cells endogenously expressing H4 receptors and in vivo in anaesthetized rats for gastric acid secretion activity. Key results: Both VUF 8430 and 4-methylhistamine were full agonists at human H4 receptors with lower affinity at rat and mouse H4 receptors. Both compounds induced chemotaxis of monocyte-derived dendritic cells. VUF 8430 also showed reasonable affinity and was a full agonist at the H3 receptor. Agmatine is a metabolite of arginine, structurally related to VUF 8430, and was a H4 receptor agonist with micromolar affinity. At histamine H3 receptors, agmatine was a full agonist, whereas 4-methylhistamine was an agonist only at high concentrations. Both VUF 8430 and agmatine were inactive at H1 and H2 receptors, whereas 4-methylhistamine is as active as histamine at H2 receptors. In vivo, VUF 8430 only caused a weak secretion of gastric acid mediated by H2 receptors, whereas 4-methylhistamine, dimaprit, histamine and amthamine, at equimolar doses, induced 2.5- to 6-fold higher output than VUF 8430. Conclusions and implications: Our results suggest complementary use of 4-methylhistamine and VUF 8430 as H4 receptor agonists. Along with H4 receptor antagonists, both agonists can serve as useful pharmacological tools in studies of histamine H4 receptors. PMID:19413569

Differential effects of AMPK agonists on cell growth and metabolism.

PubMed

Vincent, E E; Coelho, P P; Blagih, J; Griss, T; Viollet, B; Jones, R G

2015-07-01

As a sensor of cellular energy status, the AMP-activated protein kinase (AMPK) is believed to act in opposition to the metabolic phenotypes favored by proliferating tumor cells. Consequently, compounds known to activate AMPK have been proposed as cancer therapeutics. However, the extent to which the anti-neoplastic properties of these agonists are mediated by AMPK is unclear. Here we examined the AMPK dependence of six commonly used AMPK agonists (metformin, phenformin, 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), 2-deoxy-D-glucose (2DG), salicylate and A-769662) and their influence on cellular processes often deregulated in tumor cells. We demonstrate that the majority of these agonists display AMPK-independent effects on cell proliferation and metabolism with only the synthetic activator, A-769662, exerting AMPK-dependent effects on these processes. We find that A-769662 promotes an AMPK-dependent increase in mitochondrial spare respiratory capacity. Finally, contrary to the view of AMPK activity being tumor suppressive, we find that A-769662 confers a selective proliferative advantage to tumor cells growing under nutrient deprivation. Our results indicate that many of the antigrowth properties of these agonists cannot be attributed to AMPK activity in cells, and thus any observed effects using these agonists should be confirmed using AMPK-deficient cells. Ultimately, our data urge caution not only regarding the type of AMPK agonist proposed for cancer treatment but also the context in which they are used.

Differential agonist sensitivity of glycine receptor α2 subunit splice variants

PubMed Central

Miller, Paul S; Harvey, Robert J; Smart, Trevor G

2004-01-01

The glycine receptor (GlyR) α2A and α2B splice variants differ by a dual, adjacent amino acid substitution from α2AV58,T59 to α2BI58,A59 in the N-terminal extracellular domain. Comparing the effects of the GlyR agonists, glycine, β-alanine and taurine, on the GlyR α2 isoforms, revealed a significant increase in potency for all three agonists at the α2B variant. The sensitivities of the splice variants to the competitive antagonist, strychnine, and to the biphasic modulator Zn2+, were comparable. In contrast, the allosteric inhibitor picrotoxin was more potent on GlyR α2A compared to GlyR α2B receptors. Coexpression of α2A or α2B subunits with the GlyR β subunit revealed that the higher agonist potencies observed with the α2B homomer were retained for the α2Bβ heteromer. The identical sensitivity to strychnine combined with a reduction in the maximum current induced by the partial agonist taurine at the GlyR α2A homomer, suggested that the changed sensitivity to agonists is in accordance with a modulation of agonist efficacy rather than agonist affinity. An effect on agonist efficacy was also supported by using a structural model of the GlyR, localising the region of splice variation to the proposed docking region between GlyR loop 2 and the TM2-3 loop, an area associated with channel activation. The existence of a spasmodic mouse phenotype linked to a GlyR α1A52S mutation, the equivalent position to the source of the α2 splice variation, raises the possibility that the GlyR α2 splice variants may be responsible for distinct roles in neuronal function. PMID:15302677

Evaluation of novel synthetic TLR7/8 agonists as vaccine adjuvants

PubMed Central

Smith, Alyson J.; Li, Yufeng; Bazin, Hélène G.; St-Jean, Julien R.; Larocque, Daniel; Evans, Jay T.; Baldridge, Jory R.

2016-01-01

Small-molecule adjuvants that boost and direct adaptive immunity provide a powerful means to increase the effectiveness of vaccines. Through rational design several novel imidazoquinoline and oxoadenine TLR7/8 agonists, each with unique molecular modifications, were synthesized and assessed for their ability to augment adaptive immunity. All agonists bound human TLR7 and TLR8 and induced maturation of both human mDCs and pDCs. All agonists prompted production of type I interferon and/or proinflammatory cytokines, albeit with varying potencies. In most in vitro assays, the oxoadenine class of agonists proved more potent than the imidazoquinolines. Therefore, an optimized oxoadenine TLR7/8 agonist that demonstrated maximal activity in the in vitro assays was further assessed in a vaccine study with the CRM197 antigen in a porcine model. Antigen-specific antibody production was greatly enhanced in a dose dependent manner, with antibody titers increased 800-fold compared to titers from pigs vaccinated with the non-adjuvanted vaccine. Moreover, pigs vaccinated with antigen containing the highest dose of adjuvant promoted a 13-fold increase in the percentage of antigen-specific CD3+/CD8+ T cells over pigs vaccinated with antigen alone. Together this work demonstrates the promise of these novel TLR7/8 agonists as effective human vaccine adjuvants. PMID:27402566

Muscarinic agonists for the treatment of cognition in schizophrenia.

PubMed

Sellin, Angela K; Shad, Mujeeb; Tamminga, Carol

2008-11-01

It is widely accepted that cholinergic activity at muscarinic receptors is required to maintain cognitive functions, including learning and memory. Memory domains are especially impaired in schizophrenia, which may explain difficulties in psychosocial rehabilitation of individuals with this illness. However, little is known about the mechanism of this impairment. To understand our current knowledge, we reviewed the literature since 1990 via a PubMed search for the terms "muscarinic", "schizophrenia", "cognition", "memory", "learning", and "agonist" in combination. We found 89 basic science/laboratory studies, case reports/series, case-control studies, cross-sectional studies, standardized controlled animal trials, standardized controlled human trials, and reviews. Although further research is required to fully understand the neuropharmacology of the cholinergic system in cognitive function in schizophrenia, we have examined the data currently available. In general, these data suggest that agonist activity at acetylcholine muscarinic type 1 (M1) receptors would enhance memory and learning in schizophrenia. We present an overview of likely side effects of muscarinic agonists. We outline the anticholinergic activity of several available antipsychotics and review the available M1 muscarinic agonists.

FXR agonist activity of conformationally constrained analogs of GW 4064.

PubMed

Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Navas, Frank; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Bruce Wisely, G

2009-08-15

Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

Novel Apo E-Derived ABCA1 Agonist Peptide (CS-6253) Promotes Reverse Cholesterol Transport and Induces Formation of preβ-1 HDL In Vitro

PubMed Central

Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques

2015-01-01

Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from the carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

Novel apo E-derived ABCA1 agonist peptide (CS-6253) promotes reverse cholesterol transport and induces formation of preβ-1 HDL in vitro

DOE PAGES

Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; ...

2015-07-24

Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from themore » carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

The ethyl acetate fraction of a methanolic extract of unripe noni (Morinda citrifolia Linn.) fruit exhibits a biphasic effect on the dopaminergic system in mice

PubMed Central

Pandy, Vijayapandi; Narasingam, Megala; Vijeepallam, Kamini; Mohan, Syam; Mani, Vasudevan; Mohamed, Zahurin

2017-01-01

In earlier ex vivo studies, we reported the biphasic effect of a methanolic extract of unripe Morinda citrifolia fruit (MMC) on dopamine-induced contractility in isolated rat vas deferens preparations. The present in vivo study was designed and undertaken to further explore our earlier ex vivo findings. This study examined the effect of the ethyl acetate fraction of a methanolic extract of unripe Morinda citrifolia Linn. fruit (EA-MMC; 5–100 mg/kg, p.o.) on the dopaminergic system using mouse models of apomorphine-induced climbing time and climbing behavior, methamphetamine-induced stereotypy (sniffing, biting, gnawing, and licking) and haloperidol-induced catalepsy using the bar test. Acute treatment with EA-MMC at a low dose (25 mg/kg, p.o.) significantly attenuated the apomorphine-induced climbing time and climbing behavior in mice. Similarly, EA-MMC (5 and 10 mg/kg, p.o.) significantly inhibited methamphetamine-induced stereotyped behavior in mice. These results demonstrated that the antidopaminergic effect of EA-MMC was observed at relatively lower doses (<25 mg/kg, p.o.). On the other hand, EA-MMC showed dopaminergic agonistic activity at a high dose (3,000 mg/kg, p.o.), which was evident from alleviation of haloperidol (a dopamine D2 blocker)-induced catalepsy in mice. Therefore, it is concluded that EA-MMC might possess a biphasic effect on the dopaminergic system, i.e., an antagonistic effect at lower doses (<25 mg/kg, p.o.) and an agonistic effect at higher doses (>1,000 mg/kg, p.o.). However, further receptor-ligand binding assays are necessary to confirm the biphasic effects of M. citrifolia fruit on the dopaminergic system. PMID:28450692

The ethyl acetate fraction of a methanolic extract of unripe noni (Morinda citrifolia Linn.) fruit exhibits a biphasic effect on the dopaminergic system in mice.

PubMed

Pandy, Vijayapandi; Narasingam, Megala; Vijeepallam, Kamini; Mohan, Syam; Mani, Vasudevan; Mohamed, Zahurin

2017-08-05

In earlier ex vivo studies, we reported the biphasic effect of a methanolic extract of unripe Morinda citrifolia fruit (MMC) on dopamine-induced contractility in isolated rat vas deferens preparations. The present in vivo study was designed and undertaken to further explore our earlier ex vivo findings. This study examined the effect of the ethyl acetate fraction of a methanolic extract of unripe Morinda citrifolia Linn. fruit (EA-MMC; 5-100 mg/kg, p.o.) on the dopaminergic system using mouse models of apomorphine-induced climbing time and climbing behavior, methamphetamine-induced stereotypy (sniffing, biting, gnawing, and licking) and haloperidol-induced catalepsy using the bar test. Acute treatment with EA-MMC at a low dose (25 mg/kg, p.o.) significantly attenuated the apomorphine-induced climbing time and climbing behavior in mice. Similarly, EA-MMC (5 and 10 mg/kg, p.o.) significantly inhibited methamphetamine-induced stereotyped behavior in mice. These results demonstrated that the antidopaminergic effect of EA-MMC was observed at relatively lower doses (<25 mg/kg, p.o.). On the other hand, EA-MMC showed dopaminergic agonistic activity at a high dose (3,000 mg/kg, p.o.), which was evident from alleviation of haloperidol (a dopamine D 2 blocker)-induced catalepsy in mice. Therefore, it is concluded that EA-MMC might possess a biphasic effect on the dopaminergic system, i.e., an antagonistic effect at lower doses (<25 mg/kg, p.o.) and an agonistic effect at higher doses (>1,000 mg/kg, p.o.). However, further receptor-ligand binding assays are necessary to confirm the biphasic effects of M. citrifolia fruit on the dopaminergic system.

D1 receptor agonist improves sleep-wake parameters in experimental parkinsonism.

PubMed

Hyacinthe, Carole; Barraud, Quentin; Tison, François; Bezard, Erwan; Ghorayeb, Imad

2014-03-01

Both excessive daytime sleepiness (EDS) and rapid eye movement (REM) sleep deregulation are part of Parkinson's disease (PD) non-motor symptoms and may complicate dopamine replacement therapy. We report here that dopamine agonists act differentially on sleep architecture in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine macaque monkey. Continuous sleep and wake electroencephalographic monitoring revealed no effect of the selective dopamine D2 receptor agonist quinpirole on EDS, whereas the selective dopamine D1 receptor agonist SKF38393 efficiently alleviated EDS and restored REM sleep to baseline values. The present results question the relevance of abandoning D1 receptor agonist treatment in PD as it might actually improve sleep-related disorders. Copyright © 2013 Elsevier Inc. All rights reserved.

Characterization of the hypothermic effects of imidazoline I2 receptor agonists in rats

PubMed Central

Thorn, David A; An, Xiao-Fei; Zhang, Yanan; Pigini, Maria; Li, Jun-Xu

2012-01-01

BACKGROUND AND PURPOSE Imidazoline I2 receptors have been implicated in several CNS disorders. Although several I2 receptor agonists have been described, no simple and sensitive in vivo bioassay is available for studying I2 receptor ligands. This study examined I2 receptor agonist-induced hypothermia as a functional in vivo assay of I2 receptor agonism. EXPERIMENTAL APPROACH Different groups of rats were used to examine the effects of I2 receptor agonists on the rectal temperature and locomotion. The pharmacological mechanisms were investigated by combining I2 receptor ligands and different antagonists. KEY RESULTS All the selective I2 receptor agonists examined (2-BFI, diphenyzoline, phenyzoline, CR4056, tracizoline, BU224 and S22687, 3.2–56 mg·kg–1, i.p.) dose-dependently and markedly decreased the rectal temperature (hypothermia) in rats, with varied duration of action. Pharmacological mechanism of the observed hypothermia was studied by combining the I2 receptor agonists (2-BFI, BU224, tracizoline and diphenyzoline) with imidazoline I2 receptor/ α2 adrenoceptor antagonist idazoxan, selective I1 receptor antagonist efaroxan, α2 adrenoceptor antagonist/5-HT1A receptor agonist yohimbine. Idazoxan but not yohimbine or efaroxan attenuated the hypothermic effects of 2-BFI, BU224, tracizoline and diphenyzoline, supporting the I2 receptor mechanism. In contrast, both idazoxan and yohimbine attenuated hypothermia induced by the α2 adrenoceptor agonist clonidine. Among all the I2 receptor agonists studied, only S22687 markedly increased the locomotor activity in rats. CONCLUSIONS AND IMPLICATIONS Imidazoline I2 receptor agonists can produce hypothermic effects, which are primarily mediated by I2 receptors. These data suggest that I2 receptor agonist-induced hypothermia is a simple and sensitive in vivo assay for studying I2 receptor ligands. PMID:22324428

Agonist activation of α7 nicotinic acetylcholine receptors via an allosteric transmembrane site

PubMed Central

Gill, JasKiran K.; Savolainen, Mari; Young, Gareth T.; Zwart, Ruud; Sher, Emanuele; Millar, Neil S.

2011-01-01

Conventional nicotinic acetylcholine receptor (nAChR) agonists, such as acetylcholine, act at an extracellular “orthosteric” binding site located at the interface between two adjacent subunits. Here, we present evidence of potent activation of α7 nAChRs via an allosteric transmembrane site. Previous studies have identified a series of nAChR-positive allosteric modulators (PAMs) that lack agonist activity but are able to potentiate responses to orthosteric agonists, such as acetylcholine. It has been shown, for example, that TQS acts as a conventional α7 nAChR PAM. In contrast, we have found that a compound with close chemical similarity to TQS (4BP-TQS) is a potent allosteric agonist of α7 nAChRs. Whereas the α7 nAChR antagonist metyllycaconitine acts competitively with conventional nicotinic agonists, metyllycaconitine is a noncompetitive antagonist of 4BP-TQS. Mutation of an amino acid (M253L), located in a transmembrane cavity that has been proposed as being the binding site for PAMs, completely blocks agonist activation by 4BP-TQS. In contrast, this mutation had no significant effect on agonist activation by acetylcholine. Conversely, mutation of an amino acid located within the known orthosteric binding site (W148F) has a profound effect on agonist potency of acetylcholine (resulting in a shift of ∼200-fold in the acetylcholine dose-response curve), but had little effect on the agonist dose-response curve for 4BP-TQS. Computer docking studies with an α7 homology model provides evidence that both TQS and 4BP-TQS bind within an intrasubunit transmembrane cavity. Taken together, these findings provide evidence that agonist activation of nAChRs can occur via an allosteric transmembrane site. PMID:21436053

Illegal use of beta-adrenergic agonists: European Community.

PubMed

Kuiper, H A; Noordam, M Y; van Dooren-Flipsen, M M; Schilt, R; Roos, A H

1998-01-01

The use of veterinary medicinal products within the European Community is governed by a series of directives and regulations that describe the requirements for safety, quality, and efficacy of these products. Veterinary therapeutic use of beta-agonists has only been approved in the case of clenbuterol for bronchodilatation in horses and calves and for tocolysis in cows. No beta-agonists have been permitted in the European Community for growth-promoting purposes in farm animals. Surveillance for the presence of residues of veterinary agents in food-producing animals and meat is regulated by the Directive 86/469/EEC containing specific guidelines for sampling procedures on farms and in slaughterhouses. The level and frequency of sampling is dependent on the category of compounds and animal species. When positive samples have been identified (above certain action levels), sampling intensity is increased. Results of monitoring programs in EU member states during 1992 and 1993 for the occurrence of residues of beta-agonists in food-producing animals vary substantially with respect to the percentages of positive samples, ranging from 0 to 7%. The variability is partly explained by differences in sampling strategies, detection methods, and action levels applied. Identification of the proper matrices for sampling and detection of beta-agonists is important. In the case of clenbuterol, hair and choroid retinal tissue are appropriate tissues because clenbuterol accumulates in these matrices. A clear decrease in the use of clenbuterol in cattle has been observed in The Netherlands, Germany, Northern Ireland, and Spanish Basque Country over the last 3 yr. This is partly due to intensified surveillance activities at farms and slaughterhouses by governmental agencies and production sector organizations. There are data on human intoxication following consumption of liver or meat from cattle treated with beta-agonists. At the concentrations of clenbuterol measured in contaminated

Agonist-Antagonist Interaction at the Cholinergic Receptor of Denervated Diaphragm,

DTIC Science & Technology

A study has been made of the cholinergic receptor induced by chronic denervation in the rat diaphragm. The agonists acetylcholine, carbachol and...muscle cells. Supramaximally effective doses of agonists caused desensitization of the preparation; however, there was no cross tachyphylaxis between acetylcholine and carbachol . (Author)

Different skeletal effects of the peroxisome proliferator activated receptor (PPAR)α agonist fenofibrate and the PPARγ agonist pioglitazone

PubMed Central

Syversen, Unni; Stunes, Astrid K; Gustafsson, Björn I; Obrant, Karl J; Nordsletten, Lars; Berge, Rolf; Thommesen, Liv; Reseland, Janne E

2009-01-01

Background All the peroxisome proliferator activated receptors (PPARs) are found to be expressed in bone cells. The PPARγ agonist rosiglitazone has been shown to decrease bone mass in mice and thiazolidinediones (TZDs) have recently been found to increase bone loss and fracture risk in humans treated for type 2 diabetes mellitus. The aim of the study was to examine the effect of the PPARα agonist fenofibrate (FENO) and the PPARγ agonist pioglitazone (PIO) on bone in intact female rats. Methods Rats were given methylcellulose (vehicle), fenofibrate or pioglitazone (35 mg/kg body weight/day) by gavage for 4 months. BMC, BMD, and body composition were measured by DXA. Histomorphometry and biomechanical testing of excised femurs were performed. Effects of the compounds on bone cells were studied. Results The FENO group had higher femoral BMD and smaller medullary area at the distal femur; while trabecular bone volume was similar to controls. Whole body BMD, BMC, and trabecular bone volume were lower, while medullary area was increased in PIO rats compared to controls. Ultimate bending moment and energy absorption of the femoral shafts were reduced in the PIO group, while similar to controls in the FENO group. Plasma osteocalcin was higher in the FENO group than in the other groups. FENO stimulated proliferation and differentiation of, and OPG release from, the preosteoblast cell line MC3T3-E1. Conclusion We show opposite skeletal effects of PPARα and γ agonists in intact female rats. FENO resulted in significantly higher femoral BMD and lower medullary area, while PIO induced bone loss and impairment of the mechanical strength. This represents a novel effect of PPARα activation. PMID:19331671

Identification of novel selective V2 receptor non-peptide agonists.

PubMed

Del Tredici, Andria L; Vanover, Kim E; Knapp, Anne E; Bertozzi, Sine M; Nash, Norman R; Burstein, Ethan S; Lameh, Jelveh; Currier, Erika A; Davis, Robert E; Brann, Mark R; Mohell, Nina; Olsson, Roger; Piu, Fabrice

2008-10-30

Peptides with agonist activity at the vasopressin V(2) receptor are used clinically to treat fluid homeostasis disorders such as polyuria and central diabetes insipidus. Of these peptides, the most commonly used is desmopressin, which displays poor bioavailability as well as potent activity at the V(1b) receptor, with possible stress-related adverse effects. Thus, there is a strong need for the development of small molecule chemistries with selective V(2) receptor agonist activity. Using the functional cell-based assay Receptor Selection and Amplification Technology (R-SAT((R))), a screening effort identified three small molecule chemotypes (AC-94544, AC-88324, and AC-110484) with selective agonist activity at the V(2) receptor. One of these compounds, AC-94544, displayed over 180-fold selectivity at the V(2) receptor compared to related vasopressin and oxytocin receptors and no activity at 28 other G protein-coupled receptors (GPCRs). All three compounds also showed partial agonist activity at the V(2) receptor in a cAMP accumulation assay. In addition, in a rat model of central diabetes insipidus, AC-94544 was able to significantly reduce urine output in a dose-dependent manner. Thus, AC-94544, AC-88324, and AC-110484 represent novel opportunities for the treatment of disorders associated with V(2) receptor agonist deficiency.

The estrogen receptor antagonist ICI 182,780 can act both as an agonist and an inverse agonist when estrogen receptor α AF-2 is modified

PubMed Central

Movérare-Skrtic, Sofia; Börjesson, Anna E.; Farman, Helen H.; Sjögren, Klara; Windahl, Sara H.; Lagerquist, Marie K.; Andersson, Annica; Stubelius, Alexandra; Carlsten, Hans; Gustafsson, Jan-Åke; Ohlsson, Claes

2014-01-01

The bone-sparing effect of estrogen is primarily mediated via estrogen receptor (ER) α, which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand-binding domain. It was recently demonstrated that the ER antagonist ICI 182,780 (ICI) acts as an ER agonist in uterus of mice with mutations in the ERα AF-2. To evaluate the estrogen-like effects of ICI in different tissues, ovariectomized wild-type mice and mice with mutations in the ERα AF-2 (ERαAF-20) were treated with ICI, estradiol, or vehicle for 3 wk. Estradiol increased the trabecular and cortical bone mass as well as the uterine weight, whereas it reduced fat mass, thymus weight, and the growth plate height in wild-type but not in ERαAF-20 mice. Although ICI had no effect in wild-type mice, it exerted tissue-specific effects in ERαAF-20 mice. It acted as an ERα agonist on trabecular bone mass and uterine weight, whereas no effect was seen on cortical bone mass, fat mass, or thymus weight. Surprisingly, a pronounced inverse agonistic activity was seen on the growth plate height, resulting in enhanced longitudinal bone growth. In conclusion, ICI uses ERα AF-1 in a tissue-dependent manner in mice lacking ERαAF-2, resulting in no effect, agonistic activity, or inverse agonistic activity. We propose that ERα lacking AF-2 is constitutively active in the absence of ligand in the growth plate, enabling ICI to act as an inverse agonist. PMID:24395795

The estrogen receptor antagonist ICI 182,780 can act both as an agonist and an inverse agonist when estrogen receptor α AF-2 is modified.

PubMed

Movérare-Skrtic, Sofia; Börjesson, Anna E; Farman, Helen H; Sjögren, Klara; Windahl, Sara H; Lagerquist, Marie K; Andersson, Annica; Stubelius, Alexandra; Carlsten, Hans; Gustafsson, Jan-Åke; Ohlsson, Claes

2014-01-21

The bone-sparing effect of estrogen is primarily mediated via estrogen receptor (ER) α, which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand-binding domain. It was recently demonstrated that the ER antagonist ICI 182,780 (ICI) acts as an ER agonist in uterus of mice with mutations in the ERα AF-2. To evaluate the estrogen-like effects of ICI in different tissues, ovariectomized wild-type mice and mice with mutations in the ERα AF-2 (ERαAF-2(0)) were treated with ICI, estradiol, or vehicle for 3 wk. Estradiol increased the trabecular and cortical bone mass as well as the uterine weight, whereas it reduced fat mass, thymus weight, and the growth plate height in wild-type but not in ERαAF-2(0) mice. Although ICI had no effect in wild-type mice, it exerted tissue-specific effects in ERαAF-2(0) mice. It acted as an ERα agonist on trabecular bone mass and uterine weight, whereas no effect was seen on cortical bone mass, fat mass, or thymus weight. Surprisingly, a pronounced inverse agonistic activity was seen on the growth plate height, resulting in enhanced longitudinal bone growth. In conclusion, ICI uses ERα AF-1 in a tissue-dependent manner in mice lacking ERαAF-2, resulting in no effect, agonistic activity, or inverse agonistic activity. We propose that ERα lacking AF-2 is constitutively active in the absence of ligand in the growth plate, enabling ICI to act as an inverse agonist.

Evaluation of novel synthetic TLR7/8 agonists as vaccine adjuvants.

PubMed

Smith, Alyson J; Li, Yufeng; Bazin, Hélène G; St-Jean, Julien R; Larocque, Daniel; Evans, Jay T; Baldridge, Jory R

2016-08-05

Small-molecule adjuvants that boost and direct adaptive immunity provide a powerful means to increase the effectiveness of vaccines. Through rational design several novel imidazoquinoline and oxoadenine TLR7/8 agonists, each with unique molecular modifications, were synthesized and assessed for their ability to augment adaptive immunity. All agonists bound human TLR7 and TLR8 and induced maturation of both human mDCs and pDCs. All agonists prompted production of type I interferon and/or proinflammatory cytokines, albeit with varying potencies. In most in vitro assays, the oxoadenine class of agonists proved more potent than the imidazoquinolines. Therefore, an optimized oxoadenine TLR7/8 agonist that demonstrated maximal activity in the in vitro assays was further assessed in a vaccine study with the CRM197 antigen in a porcine model. Antigen-specific antibody production was greatly enhanced in a dose dependent manner, with antibody titers increased 800-fold compared to titers from pigs vaccinated with the non-adjuvanted vaccine. Moreover, pigs vaccinated with antigen containing the highest dose of adjuvant promoted a 13-fold increase in the percentage of antigen-specific CD3(+)/CD8(+) T cells over pigs vaccinated with antigen alone. Together this work demonstrates the promise of these novel TLR7/8 agonists as effective human vaccine adjuvants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Physical Chemistry to the Rescue: Differentiating Nicotinic and Cholinergic Agonists

ERIC Educational Resources Information Center

King, Angela G.

2005-01-01

Researches suggest that two agonists can bind to the same binding site of an important transmembrane protein and elicit a biological response through strikingly different binding interactions. Evidence is provided which suggests two possible types of nicotinic acetylcholine receptor agonist binding like acetlycholine (cholinergic) or like nicotine…

Endogenous cannabinoid receptor agonists inhibit neurogenic inflammations in guinea pig airways.

PubMed

Yoshihara, Shigemi; Morimoto, Hiroshi; Ohori, Makoto; Yamada, Yumi; Abe, Toshio; Arisaka, Osamu

2005-09-01

Although neurogenic inflammation via the activation of C fibers in the airway must have an important role in the pathogenesis of asthma, their regulatory mechanism remains uncertain. The pharmacological profiles of endogenous cannabinoid receptor agonists on the activation of C fibers in airway tissues were investigated and the mechanisms how cannabinoids regulate airway inflammatory reactions were clarified. The effects of endogenous cannabinoid receptor agonists on electrical field stimulation-induced bronchial smooth muscle contraction, capsaicin-induced bronchoconstriction and capsaicin-induced substance P release in guinea pig airway tissues were investigated. The influences of cannabinoid receptor antagonists and K+ channel blockers to the effects of cannabinoid receptor agonists on these respiratory reactions were examined. Both endogenous cannabinoid receptor agonists, anandamide and palmitoylethanolamide, inhibited electrical field stimulation-induced guinea pig bronchial smooth muscle contraction, but not neurokinin A-induced contraction. A cannabinoid CB2 antagonist, SR 144528, reduced the inhibitory effect of endogenous agonists, but not a cannabinoid CB1 antagonist, SR 141716A. Inhibitory effects of agonists were also reduced by the pretreatment of large conductance Ca2+ -activated K+ channel (maxi-K+ channel) blockers, iberiotoxin and charybdotoxin, but not by other K+ channel blockers, dendrotoxin or glibenclamide. Anandamide and palmitoylethanolamide blocked the capsaicin-induced release of substance P-like immunoreactivity from guinea pig airway tissues. Additionally, intravenous injection of palmitoylethanolamide dose-dependently inhibited capsaicin-induced guinea pig bronchoconstriction, but not neurokinin A-induced reaction. However, anandamide did not reduce capsaicin-induced guinea pig bronchoconstriction. These findings suggest that endogenous cannabinoid receptor agonists inhibit the activation of C fibers via cannabinoid CB2 receptors and

ApoE isoform-dependent deficits in extinction of contextual fear conditioning.

PubMed

Olsen, R H J; Agam, M; Davis, M J; Raber, J

2012-10-01

The three major human apoE isoforms (apoE2, apoE3 and apoE4) are encoded by distinct alleles (ϵ2, ϵ3 and ϵ4). Compared with ϵ3, ϵ4 is associated with increased risk to develop Alzheimer's disease (AD), cognitive impairments in Parkinson's disease (PD), and other conditions. In contrast, a recent study indicated an increased susceptibility to the recurring and re-experiencing symptom cluster of Post-Traumatic Stress Disorder (PTSD), as well as related memory impairments, in patients carrying at least one ϵ2 allele. Contextual fear conditioning and extinction are used in human and animal models to study this symptom cluster. In this study, acquisition (day 1, training), consolidation (day 2, first day of re-exposure) and extinction (days 2-5) of conditioned contextual fear in human apoE2, apoE3 and apoE4 targeted replacement and C57BL/6J wild-type (WT) mice was investigated. Male and female apoE2 showed acquisition and retrieval of conditioned fear, but failed to exhibit extinction. In contrast, WT, apoE3 and apoE4 mice showed extinction. While apoE2 mice exhibited lower freezing in response to the context on day 2 than apoE3 and apoE4 mice, this cannot explain their extinction deficit as WT mice exhibited similar freezing levels as apoE2 mice on day 2 but still exhibited extinction. Elevating freezing through extended training preserved extinction in controls, but failed to ameliorate extinction deficits in apoE2 animals. These data along with clinical data showing an association of apoE2 with susceptibility to specific symptom clusters in PTSD supports an important role for apoE isoform in the extinction of conditioned fear. © 2012 The Authors. Genes, Brain and Behavior © 2012 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.

Partial agonist therapy in schizophrenia: relevance to diminished criminal responsibility.

PubMed

Gavaudan, Gilles; Magalon, David; Cohen, Julien; Lançon, Christophe; Léonetti, Georges; Pélissier-Alicot, Anne-Laure

2010-11-01

Pathological gambling (PG), classified in the DSM-IV among impulse control disorders, is defined as inappropriate, persistent gaming for money with serious personal, family, and social consequences. Offenses are frequently committed to obtain money for gambling. Pathological gambling, a planned and structured behavioral disorder, has often been described as a complication of dopamine agonist treatment in patients with Parkinson's disease. It has never been described in patients with schizophrenia receiving dopamine agonists. We present two patients with schizophrenia, previously treated with antipsychotic drugs without any suggestion of PG, who a short time after starting aripiprazole, a dopamine partial agonist, developed PG and criminal behavior, which totally resolved when aripiprazole was discontinued. Based on recent advances in research on PG and adverse drug reactions to dopamine agonists in Parkinson's disease, we postulate a link between aripiprazole and PG in both our patients with schizophrenia and raise the question of criminal responsibility. © 2010 American Academy of Forensic Sciences.

Binary agonist surface patterns prime platelets for downstream adhesion in flowing whole blood.

PubMed

Eichinger, Colin D; Hlady, Vladimir

2017-04-28

As platelets encounter damaged vessels or biomaterials, they interact with a complex milieu of surface-bound agonists, from exposed subendothelium to adsorbed plasma proteins. It has been shown that an upstream, surface-immobilized agonist is capable of priming platelets for enhanced adhesion downstream. In this study, binary agonists were integrated into the upstream position of flow cells and the platelet priming response was measured by downstream adhesion in flowing whole blood. A nonadditive response was observed in which platelets transiently exposed to two agonists exhibited greater activation and downstream adhesion than that from the sum of either agonist alone. Antibody blocking of one of the two upstream agonists eliminated nonadditive activation and downstream adhesion. Crosstalk between platelet activation pathways likely led to a synergistic effect which created an enhanced activation response in the platelet population. The existence of synergy between platelet priming pathways is a concept that has broad implications for the field of biomaterials hemocompatibility and platelet activity testing.

Cholinergic agonists increase intracellular calcium concentration in guinea pig vestibular hair cells.

PubMed

Han, W; Zhang, S; Han, D; Jiang, S; Yang, W

2001-07-01

To better understand the cholinergic receptors in vestibular hair cells (VHC) and their subtypes, and to investigate the effects of cholinergic agonists on intracellular calcium concentration ([Ca2+]i) in guinea pig VHCs. VHCs were isolated from guinea pig crista ampullaris by enzymatic and mechanical methods. The effect of cholinergic agonists on [Ca2+]i was examined using laser scanning confocal microscopy and the Ca2+ sensitive dye Fluo-3. The results showed that the addition of acetylcholine (ACh) and carbachol (CCh), muscamic and nicotinic agonists, induced [Ca2+]i increases in all the VHCs, whereas acetylcholine bromide (ACh-Br), a nicotinic agonist, induced the [Ca2+]i increase in only a small percentage of VHCs. The ACh or CCh-induced Ca2+ response could be partially suppressed by atropine. In the presence of 0.1 mmol/L atropine, the amplitudes of ACh or CCh-induced [Ca2+]i responses became significantly smaller than those in atropine free medium (P < 0.01). The results suggest the existence of cholinergic receptors in guinea pig VHCs. It is the muscamic agonists rather than nicontic receptors that dominate [Ca2+]i variation. Atropine can suppress muscamic agonist-induced Ca2+ responses.

PPARgamma agonists inhibit TGF-beta-PKA signaling in glomerulosclerosis.

PubMed

Zou, Rong; Xu, Gang; Liu, Xiao-cheng; Han, Min; Jiang, Jing-jing; Huang, Qian; He, Yong; Yao, Ying

2010-01-01

To study the probable mechanisms of the anti-glomerulosclerosis effects induced by peroxisome proliferator-activated receptor gamma (PPARgamma) agonists in rat intraglomerular mesangial cells (MCs). Cells were transfected with the pTAL-PPRE-tk-Luc(+) plasmid and then treated with different concentrations of PPARgamma agonist, either troglitazone or telmisartan, for the indicated times. Promega luciferase assays were subsequently used for the detection of PPARgamma activation. Protein expression levels were assessed by Western blot, and PepTag assays were used for the non-radioactive detection of protein kinase A (PKA) activity. The deposition of alpha-smooth muscle actin (alpha-SMA) and p-cyclic AMP responsive element binding protein (pCREB) were analyzed by confocal laser scanning. Both troglitazone and telmisartan remarkably inhibit the PKA activation and pCREB expression that is stimulated by TGF-beta. The PPARgamma agonists also inhibited alpha-SMA and collagen IV protein expression by blocking PKA activation. PPARgamma ligands effectively suppress the activation of MCs and the accumulation of collagen IV stimulated by TGF-beta in vitro. The renal protection provided by PPARgamma agonists is partly mediated via their blockade of TGF-beta/PKA signaling.

Parents&apos; Views of Schools&apos; Involvement Efforts

ERIC Educational Resources Information Center

Rodriguez, Raymond J.; Blatz, Erin T.; Elbaum, Batya

2014-01-01

Individual and focus group interviews were conducted with 96 parents of students with disabilities in 18 schools to explore parents&apos; views of schools&apos; efforts to engage them in their child&apos;s education. A mixed-methods approach was used to identify and evaluate the relative importance of eight themes related to schools&apos; efforts…

Adenosine-A1 Receptor Agonist Induced Hyperalgesic Priming Type II

PubMed Central

Araldi, Dioneia; Ferrari, Luiz F.; Levine, Jon D.

2016-01-01

We have recently shown that repeated exposure of the peripheral terminal of the primary afferent nociceptor to the mu-opioid receptor (MOR) agonist DAMGO ([D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin acetate salt) induces a model of the transition to chronic pain that we have termed Type II hyperalgesic priming. Similar to Type I hyperalgesic priming, there is a markedly prolonged response to subsequent administration of proalgesic cytokines, prototypically prostaglandin E2 (PGE2). However, Type II hyperalgesic priming differs from Type I in being rapidly induced, protein kinase A (PKA), rather than PKCε dependent, not reversed by a protein translation inhibitor, occurring in female as well as in male rats, and isolectin B4-negative neuron dependent. We report that as with the repeated injection of a MOR agonist, the repeated administration of an agonist at the A1-adenosine receptor, also a Gi-protein coupled receptor, N6-Cyclopentyladenosine (CPA), also produces priming similar to DAMGO-induced Type II hyperalgesic priming. In this study we demonstrate that priming induced by repeated exposure to this A1-adenosine receptor agonist shares the same mechanisms as MOR-agonist induced priming. However, the prolongation of PGE2 hyperalgesia induced by repeated administration of CPA depends on G-protein αi subunit activation, differently from DAMGO-induced Type II priming, in which it depends on the β/γ subunit. These data implicate a novel form of Gi-protein signaling pathway in the Type II hyperalgesic priming induced by repeated administration of an agonist at A1-adenosine receptor to the peripheral terminal of the nociceptor. PMID:26588695

Effect of beta-agonists on LAM progression and treatment.

PubMed

Le, Kang; Steagall, Wendy K; Stylianou, Mario; Pacheco-Rodriguez, Gustavo; Darling, Thomas N; Vaughan, Martha; Moss, Joel

2018-01-30

Lymphangioleiomyomatosis (LAM), a rare disease of women, is associated with cystic lung destruction resulting from the proliferation of abnormal smooth muscle-like LAM cells with mutations in the tuberous sclerosis complex (TSC) genes TSC1 and/or TSC2 The mutant genes and encoded proteins are responsible for activation of the mechanistic target of rapamycin (mTOR), which is inhibited by sirolimus (rapamycin), a drug used to treat LAM. Patients who have LAM may also be treated with bronchodilators for asthma-like symptoms due to LAM. We observed stabilization of forced expiratory volume in 1 s over time in patients receiving sirolimus and long-acting beta-agonists with short-acting rescue inhalers compared with patients receiving only sirolimus. Because beta-agonists increase cAMP and PKA activity, we investigated effects of PKA activation on the mTOR pathway. Human skin TSC2 +/- fibroblasts or LAM lung cells incubated short-term with isoproterenol (beta-agonist) showed a sirolimus-independent increase in phosphorylation of S6, a downstream effector of the mTOR pathway, and increased cell growth. Cells incubated long-term with isoproterenol, which may lead to beta-adrenergic receptor desensitization, did not show increased S6 phosphorylation. Inhibition of PKA blocked the isoproterenol effect on S6 phosphorylation. Thus, activation of PKA by beta-agonists increased phospho-S6 independent of mTOR, an effect abrogated by beta-agonist-driven receptor desensitization. In agreement, retrospective clinical data from patients with LAM suggested that a combination of bronchodilators in conjunction with sirolimus may be preferable to sirolimus alone for stabilization of pulmonary function.

Hyperactivity and impaired response habituation in hyperdopaminergic mice

PubMed Central

Zhuang, Xiaoxi; Oosting, Ronald S.; Jones, Sara R.; Gainetdinov, Raul R.; Miller, Gary W.; Caron, Marc G.; Hen, René

2001-01-01

Abnormal dopaminergic transmission is implicated in schizophrenia, attention deficit hyperactivity disorder, and drug addiction. In an attempt to model aspects of these disorders, we have generated hyperdopaminergic mutant mice by reducing expression of the dopamine transporter (DAT) to 10% of wild-type levels (DAT knockdown). Fast-scan cyclic voltammetry and in vivo microdialysis revealed that released dopamine was cleared at a slow rate in knockdown mice, which resulted in a higher extracellular dopamine concentration. Unlike the DAT knockout mice, the DAT knockdown mice do not display a growth retardation phenotype. They have normal home cage activity but display hyperactivity and impaired response habituation in novel environments. In addition, we show that both the indirect dopamine receptor agonist amphetamine and the direct agonists apomorphine and quinpirole inhibit locomotor activity in the DAT knockdown mice, leading to the hypothesis that a shift in the balance between dopamine auto and heteroreceptor function may contribute to the therapeutic effect of psychostimulants in attention deficit hyperactivity disorder. PMID:11172062

Effects of CDP-choline on striatal dopamine level and behavior in rats.

PubMed

Shibuya, M; Kageyama, N; Taniguchi, T; Hidaka, H; Fujiwara, M

1981-02-01

To further assess the effects of CDP (cytidine diphosphate)-choline on Parkinsonian symptoms, striatal dopamine (DA) was measured fluorometrically in rats after injection of CDP-choline. CDP-choline (300 mg/kg, i.p.) increased the DA content in the striatum (p less than 0.05) one hour after injection. The behavioral effect of CDP-choline was then tested in rats in which the unilateral nigro-striatal DA neurons had degenerated following an intranigral injection of 6-hydroxydopamine (6-OHDA). CDP-choline alone did not produce behavioral changes in these rats. However, pretreatment with a single dose of CDP-choline (900 mg/kg, i.p.) suppressed both the apomorphine-induced contralateral and the d-amphetamine-induced ipsilateral circling. The same dose of CDP-choline suppressed the number of treadmill revolutions in mice. On the other hand, a 7-day consecutive treatment with 300 mg/kg of CDP-choline enhanced the apomorphine-induced contralateral circling (by 42%, p less than 0.05). The same treatment with CDP-choline raised the striatal DA content by 29% (p less than 0.05) on the intact side, but not on the 6-OHDA injected side. These results indicate that CDP-choline has either a direct nor an indirect DA agonistic effect. The increase in DA content, decrease in locomotion and enhancement of the effect of apomorphine can be explained on the hypothesis that CDP-choline may act as an antagonist on the DA neurons and receptors. The validity of this apparently paradoxical use of CDP-choline with antagonistic effect on DA neurons in the treatment of Parkinson's disease is discussed.

Classical and atypical agonists activate M1 muscarinic acetylcholine receptors through common mechanisms.

PubMed

Randáková, Alena; Dolejší, Eva; Rudajev, Vladimír; Zimčík, Pavel; Doležal, Vladimír; El-Fakahany, Esam E; Jakubík, Jan

2015-07-01

We mutated key amino acids of the human variant of the M1 muscarinic receptor that target ligand binding, receptor activation, and receptor-G protein interaction. We compared the effects of these mutations on the action of two atypical M1 functionally preferring agonists (N-desmethylclozapine and xanomeline) and two classical non-selective orthosteric agonists (carbachol and oxotremorine). Mutations of D105 in the orthosteric binding site and mutation of D99 located out of the orthosteric binding site decreased affinity of all tested agonists that was translated as a decrease in potency in accumulation of inositol phosphates and intracellular calcium mobilization. Mutation of D105 decreased the potency of the atypical agonist xanomeline more than that of the classical agonists carbachol and oxotremorine. Mutation of the residues involved in receptor activation (D71) and coupling to G-proteins (R123) completely abolished the functional responses to both classical and atypical agonists. Our data show that both classical and atypical agonists activate hM1 receptors by the same molecular switch that involves D71 in the second transmembrane helix. The principal difference among the studied agonists is rather in the way they interact with D105 in the orthosteric binding site. Furthermore, our data demonstrate a key role of D105 in xanomeline wash-resistant binding and persistent activation of hM1 by wash-resistant xanomeline. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Presenilin 1 mutations influence processing and trafficking of the ApoE receptor apoER2.

PubMed

Wang, Wei; Moerman-Herzog, Andrea M; Slaton, Arthur; Barger, Steven W

2017-01-01

Presenilin (PS)-1 is an intramembrane protease serving as the catalytic component of γ-secretase. Mutations in the PS1 gene are the most common cause of familial Alzheimer's disease (FAD). The low-density lipoprotein (LDL)-receptor family member apoER2 is a γ-secretase substrate that has been associated with AD in several ways, including acting as a receptor for apolipoprotein E (ApoE). ApoER2 is processed by γ-secretase into a C-terminal fragment (γ-CTF) that appears to regulate gene expression. FAD PS1 mutations were tested for effects on apoER2. PS1 mutation R278I showed impaired γ-secretase activity for apoER2 in the basal state or after exposure to Reelin. PS1 M146V mutation permitted accumulation of apoER2 CTFs after Reelin treatment, whereas no difference was seen between wild-type (WT) and M146V in the basal state. PS1 L282V mutation, combined with the γ-secretase inhibitor N-(N-[3,5-Difluorophenacetyl]-L-alanyl)-S-phenylglycine t-butyl ester, greatly reduced the cell-surface levels of apoER2 without affecting total apoER2 levels, suggesting a defect in receptor trafficking. These findings indicate that impaired processing or localization of apoER2 may contribute to the pathogenic effects of FAD mutations in PS1. Published by Elsevier Inc.

Antisense inhibition of apoB synthesis with mipomersen reduces plasma apoC-III and apoC-III-containing lipoproteins.

PubMed

Furtado, Jeremy D; Wedel, Mark K; Sacks, Frank M

2012-04-01

Mipomersen, an antisense oligonucleotide that reduces hepatic production of apoB, has been shown in phase 2 studies to decrease plasma apoB, LDL cholesterol (LDL-C), and triglycerides. ApoC-III inhibits VLDL and LDL clearance, and it stimulates inflammatory responses in vascular cells. Concentrations of VLDL or LDL with apoC-III independently predict cardiovascular disease. We performed an exploratory posthoc analysis on a subset of hypercholesterolemic subjects obtained from a randomized controlled dose-ranging phase 2 study of mipomersen receiving 100, 200, or 300 mg/wk, or placebo for 13 wk (n = 8 each). ApoC-III-containing lipoproteins were isolated by immuno-affinity chromatography and ultracentrifugation. Mipomersen 200 and 300 mg/wk reduced total apoC-III from baseline by 6 mg/dl (38-42%) compared with placebo group (P < 0.01), and it reduced apoC-III in both apoB lipoproteins and HDL. Mipomersen 100, 200, and 300 mg doses reduced apoB concentration of LDL with apoC-III (27%, 38%, and 46%; P < 0.05). Mipomersen reduced apoC-III concentration in HDL. The drug had no effect on apoE concentration in total plasma and in apoB lipoproteins. In summary, antisense inhibition of apoB synthesis reduced plasma concentrations of apoC-III and apoC-III-containing lipoproteins. Lower concentrations of apoC-III and LDL with apoC-III are associated with reduced risk of coronary heart disease (CHD) in epidemiologic studies independent of traditional risk factors.

Antisense inhibition of apoB synthesis with mipomersen reduces plasma apoC-III and apoC-III-containing lipoproteins

PubMed Central

Furtado, Jeremy D.; Wedel, Mark K.; Sacks, Frank M.

2012-01-01

Mipomersen, an antisense oligonucleotide that reduces hepatic production of apoB, has been shown in phase 2 studies to decrease plasma apoB, LDL cholesterol (LDL-C), and triglycerides. ApoC-III inhibits VLDL and LDL clearance, and it stimulates inflammatory responses in vascular cells. Concentrations of VLDL or LDL with apoC-III independently predict cardiovascular disease. We performed an exploratory posthoc analysis on a subset of hypercholesterolemic subjects obtained from a randomized controlled dose-ranging phase 2 study of mipomersen receiving 100, 200, or 300 mg/wk, or placebo for 13 wk (n = 8 each). ApoC-III–containing lipoproteins were isolated by immuno-affinity chromatography and ultracentrifugation. Mipomersen 200 and 300 mg/wk reduced total apoC-III from baseline by 6 mg/dl (38–42%) compared with placebo group (P < 0.01), and it reduced apoC-III in both apoB lipoproteins and HDL. Mipomersen 100, 200, and 300 mg doses reduced apoB concentration of LDL with apoC-III (27%, 38%, and 46%; P < 0.05). Mipomersen reduced apoC-III concentration in HDL. The drug had no effect on apoE concentration in total plasma and in apoB lipoproteins. In summary, antisense inhibition of apoB synthesis reduced plasma concentrations of apoC-III and apoC-III–containing lipoproteins. Lower concentrations of apoC-III and LDL with apoC-III are associated with reduced risk of coronary heart disease (CHD) in epidemiologic studies independent of traditional risk factors. PMID:22301884

Interaction of ApoE3 and ApoE4 isoforms with an ITM2b/BRI2 mutation linked to the Alzheimer disease-like Danish dementia: Effects on learning and memory

PubMed Central

Biundo, Fabrizio; Ishiwari, Keita; Del Prete, Dolores; D’Adamio, Luciano

2015-01-01

Mutations in Amyloid β Precursor Protein (APP) and in genes that regulate APP processing – such as PSEN1/2 and ITM2b/BRI2 – cause familial dementia, such Familial Alzheimer disease (FAD), Familial Danish (FDD) and British (FBD) dementias. The ApoE gene is the major genetic risk factor for sporadic AD. Three major variants of ApoE exist in humans (ApoE2, ApoE3, and ApoE4), with the ApoE4 allele being strongly associated with AD. ITM2b/BRI2 is also a candidate regulatory node genes predicted to mediate the common patterns of gene expression shared by healthy ApoE4 carriers and late-onset AD patients not carrying ApoE4. This evidence provides a direct link between ITM2b/BRI2 and ApoE4. To test whether ApoE4 and pathogenic ITM2b/BRI2 interact to modulate learning and memory, we crossed a mouse carrying the ITM2b/BRI2 mutations that causes FDD knocked-in the endogenous mouse Itm2b/Bri2 gene (FDDKI mice) with human ApoE3 and ApoE4 targeted replacement mice. The resultant ApoE3, FDDKI/ApoE3, ApoE4, FDDKI/ApoE4 male mice were assessed longitudinally for learning and memory at 4, 6, 12, and 16– 17 months of age. The results showed that ApoE4-carrying mice displayed spatial working/short-term memory deficits relative to ApoE3-carrying mice starting in early middle age, while long-term spatial memory of ApoE4 mice was not adversely affected even at 16–17 months, and that the FDD mutation impaired working/short-term spatial memory in ApoE3-carrying mice and produced impaired long-term spatial memory in ApoE4-carrying mice in middle age. The present results suggest that the FDD mutation may differentially affect learning and memory in ApoE4 carriers and non-carriers. PMID:26528887

Interaction of ApoE3 and ApoE4 isoforms with an ITM2b/BRI2 mutation linked to the Alzheimer disease-like Danish dementia: Effects on learning and memory.

PubMed

Biundo, Fabrizio; Ishiwari, Keita; Del Prete, Dolores; D'Adamio, Luciano

2015-12-01

Mutations in Amyloid β Precursor Protein (APP) and in genes that regulate APP processing--such as PSEN1/2 and ITM2b/BRI2--cause familial dementia, such Familial Alzheimer disease (FAD), Familial Danish (FDD) and British (FBD) dementias. The ApoE gene is the major genetic risk factor for sporadic AD. Three major variants of ApoE exist in humans (ApoE2, ApoE3, and ApoE4), with the ApoE4 allele being strongly associated with AD. ITM2b/BRI2 is also a candidate regulatory node genes predicted to mediate the common patterns of gene expression shared by healthy ApoE4 carriers and late-onset AD patients not carrying ApoE4. This evidence provides a direct link between ITM2b/BRI2 and ApoE4. To test whether ApoE4 and pathogenic ITM2b/BRI2 interact to modulate learning and memory, we crossed a mouse carrying the ITM2b/BRI2 mutations that causes FDD knocked-in the endogenous mouse Itm2b/Bri2 gene (FDDKI mice) with human ApoE3 and ApoE4 targeted replacement mice. The resultant ApoE3, FDDKI/ApoE3, ApoE4, FDDKI/ApoE4 male mice were assessed longitudinally for learning and memory at 4, 6, 12, and 16-17 months of age. The results showed that ApoE4-carrying mice displayed spatial working/short-term memory deficits relative to ApoE3-carrying mice starting in early middle age, while long-term spatial memory of ApoE4 mice was not adversely affected even at 16-17 months, and that the FDD mutation impaired working/short-term spatial memory in ApoE3-carrying mice and produced impaired long-term spatial memory in ApoE4-carrying mice in middle age. The present results suggest that the FDD mutation may differentially affect learning and memory in ApoE4 carriers and non-carriers. Copyright © 2015 Elsevier Inc. All rights reserved.

Opioid-receptor subtype agonist-induced enhancements of sucrose intake are dependent upon sucrose concentration.

PubMed

Ruegg, H; Yu, W Z; Bodnar, R J

1997-07-01

Selective mu ([D-Ala2, N-Me-Phe4, Gly-ol5]-enkephalin (DAMGO)), delta1 ([D-Pen2, D-Pen5]-enkephalin (DPDPE)), delta2 ([D-Ala2, Glu4]-Deltorphin (Delt II)), kappa1 (U50488H) and kappa3 (naloxone benzoylhydrazone (NalBzOH)) opioid agonists each stimulate food intake in rats. Whereas studies with selective opioid antagonists implicate mu and kappa1 receptors in the mediation of sucrose intake, studies with selective opioid agonists implicate mu and delta receptors in the mediation of saccharin intake. The present study determined if specific delta1, delta2, kappa1, kappa3 and mu opioid-receptor subtype agonists produced similar alterations in sucrose intake as a function of sucrose concentration (0.5%, 2.5%, 10%) across a 1-h time-course. Each of these agonists significantly increased sucrose intake with variations in pattern, magnitude, and consistency as a function of sucrose concentration. Whereas the mu opioid agonist, DAMGO, and the delta1 opioid agonist, DPDPE, each enhanced sucrose intake at higher (2.5%, 10%), but not lower (0.5%), concentrations, the delta2 opioid agonist, Delt II, increased sucrose intake at lower (0.5%, 2.5%), but not higher (10%), concentrations. Kappa opioid agonists produced less consistent effects. The kappa1 opioid agonist, U50488H, increased sucrose intake at high (10%) concentrations and decreased sucrose intake at low (0.5%) concentrations, and the kappa3 opioid agonist, NalBzOH, inconsistently increased sucrose intake at the 0.5% (20 microg) and 10% (1 microg) concentrations. Thus, these data further implicate mu, delta1, and delta2 opioid mediation of palatable intake, particularly of its orosensory characteristics.

Generalized concentration addition: a method for examining mixtures containing partial agonists.

PubMed

Howard, Gregory J; Webster, Thomas F

2009-08-07

Environmentally relevant toxic exposures often consist of simultaneous exposure to multiple agents. Methods to predict the expected outcome of such combinations are critical both to risk assessment and to an accurate judgment of whether combinations are synergistic or antagonistic. Concentration addition (CA) has commonly been used to assess the presence of synergy or antagonism in combinations of similarly acting chemicals, and to predict effects of combinations of such agents. CA has the advantage of clear graphical interpretation: Curves of constant joint effect (isoboles) must be negatively sloped straight lines if the mixture is concentration additive. However, CA cannot be directly used to assess combinations that include partial agonists, although such agents are of considerable interest. Here, we propose a natural extension of CA to a functional form that may be applied to mixtures including full agonists and partial agonists. This extended definition, for which we suggest the term "generalized concentration addition," encompasses linear isoboles with slopes of any sign. We apply this approach to the simple example of agents with dose-response relationships described by Hill functions with slope parameter n=1. The resulting isoboles are in all cases linear, with negative, zero and positive slopes. Using simple mechanistic models of ligand-receptor systems, we show that the same isobole pattern and joint effects are generated by modeled combinations of full and partial agonists. Special cases include combinations of two full agonists and a full agonist plus a competitive antagonist.

Interaction between the mu-agonist dermorphin and the delta-agonist [D-Ala2, Glu4]deltorphin in supraspinal antinociception and delta-opioid receptor binding.

PubMed Central

Negri, L.; Improta, G.; Lattanzi, R.; Potenza, R. L.; Luchetti, F.; Melchiorri, P.

1995-01-01

1. In rats, the interaction between the mu-opioid agonist dermorphin and the delta-opioid agonist [D-Ala2, Glu4]deltorphin was studied in binding experiments to delta-opioid receptors and in the antinociceptive test to radiant heat. 2. When injected i.c.v., doses of [D-Ala2, Glu4]deltorphin higher than 20 nmol produced antinociception in the rat tail-flick test to radiant heat. Lower doses were inactive. None of the doses tested elicited the maximum achievable response. This partial antinociception was accomplished with an in vivo occupancy of more than 97% of brain delta-opioid receptors and of 17% of mu-opioid receptors. Naloxone (0.1 mg kg-1, s.c.), and naloxonazine (10 mg kg-1, i.v., 24 h before), but not the selective delta-opioid antagonist naltrindole, antagonized the antinociception. 3. In vitro competitive inhibition studies in rat brain membranes showed that [D-Ala2, Glu4]deltorphin displaced [3H]-naltrindole from two delta-binding sites of high and low affinity. The addition of 100 microM Gpp[NH]p produced a three fold increase in the [D-Ala2, Glu4]deltorphin Ki value for both binding sites. The addition of 10 nM dermorphin increased the Ki value of the delta-agonist for the high affinity site five times. When Gpp[NH]p was added to the incubation medium together with 10 nM dermorphin, the high affinity Ki of the delta-agonist increased 15 times. 4. Co-administration into the rat brain ventricles of subanalgesic doses of dermorphin and [D-Ala2, Glu4]deltorphin resulted in synergistic antinociceptive responses. 5. Pretreatment with naloxone or with the non-equilibrium mu-antagonists naloxonazine and beta-funaltrexamine completely abolished the antinociceptive response of the mu-delta agonist combinations. 6. Pretreatment with the delta-opioid antagonists naltrindole and DALCE reduced the antinociceptive response of the dermorphin-[D-Ala2, Glu4]deltorphin combinations to a value near that observed after the mu-agonist alone. At the dosage used, naltrindole

Small-molecule agonists for the glucagon-like peptide 1 receptor

PubMed Central

Knudsen, Lotte Bjerre; Kiel, Dan; Teng, Min; Behrens, Carsten; Bhumralkar, Dilip; Kodra, János T.; Holst, Jens J.; Jeppesen, Claus B.; Johnson, Michael D.; de Jong, Johannes Cornelis; Jorgensen, Anker Steen; Kercher, Tim; Kostrowicki, Jarek; Madsen, Peter; Olesen, Preben H.; Petersen, Jacob S.; Poulsen, Fritz; Sidelmann, Ulla G.; Sturis, Jeppe; Truesdale, Larry; May, John; Lau, Jesper

2007-01-01

The peptide hormone glucagon-like peptide (GLP)-1 has important actions resulting in glucose lowering along with weight loss in patients with type 2 diabetes. As a peptide hormone, GLP-1 has to be administered by injection. Only a few small-molecule agonists to peptide hormone receptors have been described and none in the B family of the G protein coupled receptors to which the GLP-1 receptor belongs. We have discovered a series of small molecules known as ago-allosteric modulators selective for the human GLP-1 receptor. These compounds act as both allosteric activators of the receptor and independent agonists. Potency of GLP-1 was not changed by the allosteric agonists, but affinity of GLP-1 for the receptor was increased. The most potent compound identified stimulates glucose-dependent insulin release from normal mouse islets but, importantly, not from GLP-1 receptor knockout mice. Also, the compound stimulates insulin release from perfused rat pancreas in a manner additive with GLP-1 itself. These compounds may lead to the identification or design of orally active GLP-1 agonists. PMID:17213325

beta-Adrenoceptor agonists enhance 5-hydroxytryptamine-mediated behavioural responses.

PubMed Central

Cowen, P. J.; Grahame-Smith, D. G.; Green, A. R.; Heal, D. J.

1982-01-01

The beta-adrenoceptor agonists, salbutamol, terbutaline and clenbuterol, were investigated for their effect on 5-hydroxytryptamine-mediated (5-HT) hyperactivity. 2 The lipophilic beta-adrenoceptor agonist, clenbuterol (5 mg/kg) enhanced the behaviours induced by quipazine (25 mg/kg), including headweaving, forepaw treading and hind-limb abduction and thus increased automated activity recording. Clenbuterol (5 mg/kg) also enhanced the hyperactivity syndrome produced by the 5-HT agonist, 5-methoxy N,N-dimethyltryptamine (2 mg/kg) and the combination of tranylcypromine (10 mg/kg) and L-tryptophan (50 mg/kg). Salbutamol and terbutaline potentiated quipazine-induced hyperactivity only when given at the higher dose of 20 mg/kg. 3 The effect of clenbuterol in enhancing quipazine hyperactivity was blocked by the centrally acting beta 1-adrenoceptor antagonist, metoprolol (5 mg/kg), but not by the beta 2-adrenoceptor antagonist, butoxamine (5 mg/kg) or the peripherally acting beta 1-adrenoceptor antagonist, atenolol (5 mg/kg). 4 Clenbuterol (5 mg/kg) did not enhance the circling responses produced by methamphetamine (0.5 mg/kg) in unilateral nigrostriatal-lesioned rats. 5 The results suggest that beta-adrenoceptor agonists in common with some established antidepressant treatments produce enhancement of 5-HT-mediated behavioural responses. PMID:6124294

Long-acting beta 2-agonists in chronic obstructive pulmonary disease.

PubMed

Llewellyn-Jones, Carol

2002-01-01

Until recently, the use of long-acting beta 2-agonists in chronic obstructive pulmonary disease has been understated. There is now evidence that they may offer benefits beyond bronchodilation. This article reviews the management of chronic obstructive pulmonary disease and looks at the place of long-acting beta 2-agonists as a first-line treatment option.

Importance of agonists in alpha-adrenoceptor classification and localisation of alpha1-adrenoceptors in human prostate.

PubMed

McGrath, J C; Naghadeh, M A; Pediani, J D; Mackenzie, J F; Daly, C J

1999-01-01

alpha-Adrenoceptor blocker drugs are commonly used in the clinical (non-surgical) treatment of BPH. alpha1-adrenoceptors were originally sub-divided using agonists but, subsequently, were sub-divided using only antagonists in ligand-ligand interactions, which did not require agonists at all. Ultimately, proof that adrenoceptors are functional receptors for the natural ligands, noradrenaline and adrenaline, requires that agonists be used. The earlier excitement engendered by finding varying agonist potency series in different tissues has not been revisited to place it in the context of current concepts of alpha1-adrenoceptor subtypes. This review will consider the advantages and limitations of different agonists for the study of alpha1-adrenoceptor subtypes including 'extreme' examples where the archetypal alpha1-adrenoceptor agonist phenylephrine activates alpha2-adrenoceptors and others where UK14304, often the alpha2-adrenoceptor agonist of choice, activates alpha1-adrenoceptors. New work will also be presented showing the interaction between agonists and the fluorescent alpha1-adrenoceptor antagonist QAPB. This introduces the novel point of view of studying the displacement of antagonists by agonists. Possible errors in antagonist classification arising from complexity in the actions of agonists and the recently developed method of fluorescent ligand binding on isolated living human prostatic smooth muscle cells will be discussed.

Flow-injection chemiluminescence method to detect a β2 adrenergic agonist.

PubMed

Zhang, Guangbin; Tang, Yuhai; Shang, Jian; Wang, Zhongcheng; Yu, Hua; Du, Wei; Fu, Qiang

2015-02-01

A new method for the detection of β2 adrenergic agonists was developed based on the chemiluminescence (CL) reaction of β2 adrenergic agonist with potassium ferricyanide-luminol CL. The effect of β2 adrenergic agonists including isoprenaline hydrochloride, salbutamol sulfate, terbutaline sulfate and ractopamine on the CL intensity of potassium ferricyanide-luminol was discovered. Detection of the β2 adrenergic agonist was carried out in a flow system. Using uniform design experimentation, the influence factors of CL were optimized. The optimal experimental conditions were 1 mmol/L of potassium ferricyanide, 10 µmol/L of luminol, 1.2 mmol/L of sodium hydroxide, a flow speed of 2.6 mL/min and a distance of 1.2 cm from 'Y2 ' to the flow cell. The linear ranges and limit of detection were 10-100 and 5 ng/mL for isoprenaline hydrochloride, 20-100 and 5 ng/mL for salbutamol sulfate, 8-200 and 1 ng/mL for terbutaline sulfate, 20-100 and 4 ng/mL for ractopamine, respectively. The proposed method allowed 200 injections/h with excellent repeatability and precision. It was successfully applied to the determination of three β2 adrenergic agonists in commercial pharmaceutical formulations with recoveries in the range of 96.8-98.5%. The possible CL reaction mechanism of potassium ferricyanide-luminol-β2 adrenergic agonist was discussed from the UV/vis spectra. Copyright © 2014 John Wiley & Sons, Ltd.

Update in TSH Receptor Agonists and Antagonists

PubMed Central

Neumann, Susanne

2012-01-01

The physiological role of the TSH receptor (TSHR) as a major regulator of thyroid function is well understood, but TSHRs are also expressed in multiple normal extrathyroidal tissues, and the physiological roles of TSHRs in these tissues are unclear. Moreover, TSHRs play a major role in several pathological conditions including hyperthyroidism, hypothyroidism, and thyroid tumors. Small molecule, “drug-like” TSHR agonists, neutral antagonists, and inverse agonists may be useful as probes of TSHR function in extrathyroidal tissues and as leads to develop drugs for several diseases of the thyroid. In this Update, we review the most recent findings regarding the development and use of these small molecule TSHR ligands. PMID:23019348

Targeted Delivery of LXR Agonist Using a Site-Specific Antibody-Drug Conjugate.

PubMed

Lim, Reyna K V; Yu, Shan; Cheng, Bo; Li, Sijia; Kim, Nam-Jung; Cao, Yu; Chi, Victor; Kim, Ji Young; Chatterjee, Arnab K; Schultz, Peter G; Tremblay, Matthew S; Kazane, Stephanie A

2015-11-18

Liver X receptor (LXR) agonists have been explored as potential treatments for atherosclerosis and other diseases based on their ability to induce reverse cholesterol transport and suppress inflammation. However, this therapeutic potential has been hindered by on-target adverse effects in the liver mediated by excessive lipogenesis. Herein, we report a novel site-specific antibody-drug conjugate (ADC) that selectively delivers a LXR agonist to monocytes/macrophages while sparing hepatocytes. The unnatural amino acid para-acetylphenylalanine (pAcF) was site-specifically incorporated into anti-CD11a IgG, which binds the α-chain component of the lymphocyte function-associated antigen 1 (LFA-1) expressed on nearly all monocytes and macrophages. An aminooxy-modified LXR agonist was conjugated to anti-CD11a IgG through a stable, cathepsin B cleavable oxime linkage to afford a chemically defined ADC. The anti-CD11a IgG-LXR agonist ADC induced LXR activation specifically in human THP-1 monocyte/macrophage cells in vitro (EC50-27 nM), but had no significant effect in hepatocytes, indicating that payload delivery is CD11a-mediated. Moreover, the ADC exhibited higher-fold activation compared to a conventional synthetic LXR agonist T0901317 (Tularik) (3-fold). This novel ADC represents a fundamentally different strategy that uses tissue targeting to overcome the limitations of LXR agonists for potential use in treating atherosclerosis.

Human ApoE Isoforms Differentially Modulate Glucose and Amyloid Metabolic Pathways in Female Brain: Evidence of the Mechanism of Neuroprotection by ApoE2 and Implications for Alzheimer's Disease Prevention and Early Intervention.

PubMed

Keeney, Jeriel Thomas-Richard; Ibrahimi, Shaher; Zhao, Liqin

2015-01-01

Three major genetic isoforms of apolipoprotein E (ApoE), ApoE2, ApoE3, and ApoE4, exist in humans and lead to differences in susceptibility to Alzheimer's disease (AD). This study investigated the impact of human ApoE isoforms on brain metabolic pathways involved in glucose utilization and amyloid-β (Aβ) degradation, two major areas that are significantly perturbed in preclinical AD. Hippocampal RNA samples from middle-aged female mice with targeted human ApoE2, ApoE3, and ApoE4 gene replacement were comparatively analyzed with a qRT-PCR custom array for the expression of 85 genes involved in insulin/insulin-like growth factor (Igf) signaling. Consistent with its protective role against AD, ApoE2 brain exhibited the most metabolically robust profile among the three ApoE genotypes. When compared to ApoE2 brain, both ApoE3 and ApoE4 brains exhibited markedly reduced levels of Igf1, insulin receptor substrates (Irs), and facilitated glucose transporter 4 (Glut4), indicating reduced glucose uptake. Additionally, ApoE4 brain exhibited significantly decreased Pparg and insulin-degrading enzyme (Ide), indicating further compromised glucose metabolism and Aβ dysregulation associated with ApoE4. Protein analysis showed significantly decreased Igf1, Irs, and Glut4 in ApoE3 brain, and Igf1, Irs, Glut4, Pparg, and Ide in ApoE4 brain compared to ApoE2 brain. These data provide the first documented evidence that human ApoE isoforms differentially affect brain insulin/Igf signaling and downstream glucose and amyloid metabolic pathways, illustrating a potential mechanism for their differential risk in AD. A therapeutic strategy that enhances brain insulin/Igf1 signaling activity to a more robust ApoE2-like phenotype favoring both energy production and amyloid homeostasis holds promise for AD prevention and early intervention.

Evaluation of peroxisome proliferator-activated receptor agonists on interleukin-5-induced eosinophil differentiation

PubMed Central

Smith, Steven G; Hill, Mike; Oliveria, John-Paul; Watson, Brittany M; Baatjes, Adrian J; Dua, Benny; Howie, Karen; Campbell, Heather; Watson, Rick M; Sehmi, Roma; Gauvreau, Gail M

2014-01-01

Peroxisome proliferator-activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin-5 (IL-5) -induced eosinophil differentiation from haemopoietic progenitor cells. Non-adherent mononuclear cells or CD34+ cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult® cultures with IL-5 (10 ng/ml) and IL-3 (25 ng/ml) in the presence of 1–1000 nm PPARα agonist (GW9578), PPARβ/δ agonist (GW501516), PPARγ agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony-forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood-extracted CD34+ cells cultured with IL-5 or IL-5 + IL-3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm, P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL-5-induced phosphorylation of extracellular signal-regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal-regulated kinase 1/2 signalling pathway. These findings indicate that the PPARγ agonist can attenuate tissue eosinophilia by interfering with local differentiative responses. PMID:24628018

β-Agonist-mediated Relaxation of Airway Smooth Muscle Is Protein Kinase A-dependent*

PubMed Central

Morgan, Sarah J.; Deshpande, Deepak A.; Tiegs, Brian C.; Misior, Anna M.; Yan, Huandong; Hershfeld, Alena V.; Rich, Thomas C.; Panettieri, Reynold A.; An, Steven S.; Penn, Raymond B.

2014-01-01

Inhaled β-agonists are effective at reversing bronchoconstriction in asthma, but the mechanism by which they exert this effect is unclear and controversial. PKA is the historically accepted effector, although this assumption is made on the basis of associative and not direct evidence. Recent studies have asserted that exchange protein activated by cAMP (Epac), not PKA, mediates the relaxation of airway smooth muscle (ASM) observed with β-agonist treatment. This study aims to clarify the role of PKA in the prorelaxant effects of β-agonists on ASM. Inhibition of PKA activity via expression of the PKI and RevAB peptides results in increased β-agonist-mediated cAMP release, abolishes the inhibitory effect of isoproterenol on histamine-induced intracellular calcium flux, and significantly attenuates histamine-stimulated MLC-20 phosphorylation. Analyses of ASM cell and tissue contraction demonstrate that PKA inhibition eliminates most, if not all, β-agonist-mediated relaxation of contracted smooth muscle. Conversely, Epac knockdown had no effect on the regulation of contraction or procontractile signaling by isoproterenol. These findings suggest that PKA, not Epac, is the predominant and physiologically relevant effector through which β-agonists exert their relaxant effects. PMID:24973219

Self-Administration of Cocaine Induces Dopamine-Independent Self-Administration of Sigma Agonists

PubMed Central

Hiranita, Takato; Mereu, Maddalena; Soto, Paul L; Tanda, Gianluigi; Katz, Jonathan L

2013-01-01

Sigma1 receptors (σ1Rs) are intracellularly mobile chaperone proteins implicated in several disease processes, as well as psychiatric disorders and substance abuse. Here we report that although selective σ1R agonists (PRE-084, (+)-pentazocine) lacked reinforcing effects in drug-naive rats, over the course of 28 experimental sessions, which was more than sufficient for acquisition of cocaine self-administration, responding was not maintained by either σ1R agonist. In contrast, after subjects self-administered cocaine σ1R agonists were readily self-administered. The induced reinforcing effects were long lasting; a response for which subjects had no history of reinforcement was newly conditioned with both σ1R agonists, extinguished when injections were discontinued, and reconditioned when σ1R agonists again followed responses. Experience with food reinforcement was ineffective as an inducer of σ1R agonist reinforcement. Although a variety of dopamine receptor antagonists blocked cocaine self-administration, consistent with its dopaminergic mechanism, PRE-084 self-administration was entirely insensitive to these drugs. Conversely, the σR antagonist, BD1063, blocked PRE-084 self-administration but was inactive against cocaine. In microdialysis studies i.v. PRE-084 did not significantly stimulate dopamine at doses that were self-administered in rats either with or without a cocaine self-administration experience. The results indicate that cocaine experience induces reinforcing effects of previously inactive σ1R agonists, and that the mechanism underlying these reinforcing effects is dopamine independent. It is further suggested that induced σ1R mechanisms may have an essential role in treatment-resistant stimulant abuse, suggesting new approaches for the development of effective medications for stimulant abuse. PMID:23187725

Self-administration of cocaine induces dopamine-independent self-administration of sigma agonists.

PubMed

Hiranita, Takato; Mereu, Maddalena; Soto, Paul L; Tanda, Gianluigi; Katz, Jonathan L

2013-03-01

Sigma(1) receptors (σ(1)Rs) are intracellularly mobile chaperone proteins implicated in several disease processes, as well as psychiatric disorders and substance abuse. Here we report that although selective σ(1)R agonists (PRE-084, (+)-pentazocine) lacked reinforcing effects in drug-naive rats, over the course of 28 experimental sessions, which was more than sufficient for acquisition of cocaine self-administration, responding was not maintained by either σ(1)R agonist. In contrast, after subjects self-administered cocaine σ(1)R agonists were readily self-administered. The induced reinforcing effects were long lasting; a response for which subjects had no history of reinforcement was newly conditioned with both σ(1)R agonists, extinguished when injections were discontinued, and reconditioned when σ(1)R agonists again followed responses. Experience with food reinforcement was ineffective as an inducer of σ(1)R agonist reinforcement. Although a variety of dopamine receptor antagonists blocked cocaine self-administration, consistent with its dopaminergic mechanism, PRE-084 self-administration was entirely insensitive to these drugs. Conversely, the σR antagonist, BD1063, blocked PRE-084 self-administration but was inactive against cocaine. In microdialysis studies i.v. PRE-084 did not significantly stimulate dopamine at doses that were self-administered in rats either with or without a cocaine self-administration experience. The results indicate that cocaine experience induces reinforcing effects of previously inactive σ(1)R agonists, and that the mechanism underlying these reinforcing effects is dopamine independent. It is further suggested that induced σ(1)R mechanisms may have an essential role in treatment-resistant stimulant abuse, suggesting new approaches for the development of effective medications for stimulant abuse.

Perioperative use of selective alpha-2 agonists and antagonists in small animals

PubMed Central

2004-01-01

Abstract Alpha-2 agonists are the only single class of anesthetic drugs that induce reliable, dose-dependent sedation, analgesia, and muscle relaxation in dogs and cats. Used at low doses, as adjuncts to injectable and inhalational anesthetics, selective alpha-2 agonists dramatically reduce the amount of anesthetic drug required to induce and maintain anesthesia. This reduction in anesthetic requirements is achieved without significant depression of pulmonary function and with limited effects on cardiovascular function. Selective alpha-2 agonists can also be used postoperatively to potentiate the analgesic effects of opioids and other drugs. Given the nearly ideal pharmacodynamic profile and reversibility of alpha-2 agonists, these drugs will play a central role in balanced approaches to anesthesia and the management of perioperative pain in healthy dogs and cats. PMID:15283516

Extrinsic factors regulate partial agonist efficacy of strychnine-sensitive glycine receptors

PubMed Central

Farroni, Jeffrey S; McCool, Brian A

2004-01-01

Background Strychnine-sensitive glycine receptors in many adult forebrain regions consist of alpha2 + beta heteromeric channels. This subunit composition is distinct from the alpha1 + beta channels found throughout the adult spinal cord. Unfortunately, the pharmacology of forebrain alpha2beta receptors are poorly defined compared to 'neonatal' alpha2 homomeric channels or 'spinal' alpha1beta heteromers. In addition, the pharmacologic properties of native alpha2beta glycine receptors have been generally distinct from receptors produced by heterologous expression. To identify subtype-specific pharmacologic tools for the forebrain alpha2beta receptors, it is important to identify a heterologous expression system that closely resembles these native glycine-gated chloride channels. Results While exploring pharmacological properties of alpha2beta glycine receptors compared to alpha2-homomers, we found that distinct heterologous expression systems appeared to differentially influence partial agonist pharmacology. The β-amino acid taurine possessed 30–50% efficacy for alpha2-containing receptor isoforms when expressed in HEK 293 cells. However, taurine efficacy was dramatically reduced in L-cell fibroblasts. Similar results were obtained for β-alanine. The efficacy of these partial agonists was also strongly reduced by the beta subunit. There were no significant differences in apparent strychnine affinity values calculated from concentration-response data between expression systems or subunit combinations. Nor did relative levels of expression correlate with partial agonist efficacy when compared within or between several different expression systems. Finally, disruption of the tubulin cytoskeleton reduced the efficacy of partial agonists in a subunit-dependent, but system-independent, fashion. Conclusions Our results suggest that different heterologous expression systems can dramatically influence the agonist pharmacology of strychnine-sensitive glycine receptors. In

Extrinsic factors regulate partial agonist efficacy of strychnine-sensitive glycine receptors.

PubMed

Farroni, Jeffrey S; McCool, Brian A

2004-08-09

Strychnine-sensitive glycine receptors in many adult forebrain regions consist of alpha2 + beta heteromeric channels. This subunit composition is distinct from the alpha1 + beta channels found throughout the adult spinal cord. Unfortunately, the pharmacology of forebrain alpha2beta receptors are poorly defined compared to 'neonatal' alpha2 homomeric channels or 'spinal' alpha1beta heteromers. In addition, the pharmacologic properties of native alpha2beta glycine receptors have been generally distinct from receptors produced by heterologous expression. To identify subtype-specific pharmacologic tools for the forebrain alpha2beta receptors, it is important to identify a heterologous expression system that closely resembles these native glycine-gated chloride channels. While exploring pharmacological properties of alpha2beta glycine receptors compared to alpha2-homomers, we found that distinct heterologous expression systems appeared to differentially influence partial agonist pharmacology. The beta-amino acid taurine possessed 30-50% efficacy for alpha2-containing receptor isoforms when expressed in HEK 293 cells. However, taurine efficacy was dramatically reduced in L-cell fibroblasts. Similar results were obtained for beta-alanine. The efficacy of these partial agonists was also strongly reduced by the beta subunit. There were no significant differences in apparent strychnine affinity values calculated from concentration-response data between expression systems or subunit combinations. Nor did relative levels of expression correlate with partial agonist efficacy when compared within or between several different expression systems. Finally, disruption of the tubulin cytoskeleton reduced the efficacy of partial agonists in a subunit-dependent, but system-independent, fashion. Our results suggest that different heterologous expression systems can dramatically influence the agonist pharmacology of strychnine-sensitive glycine receptors. In the systems examine here

Do agonistic motives matter more than anger? Three studies of cardiovascular risk in adolescents.

PubMed

Ewart, Craig K; Elder, Gavin J; Smyth, Joshua M; Sliwinski, Martin J; Jorgensen, Randall S

2011-09-01

Three motivational profiles have been associated with recurring psychological stress in low-income youth and young adults: Striving to control others (agonistic striving), striving to control the self (transcendence striving), and not asserting control (dissipated striving). Agonistic striving has been associated with elevated ambulatory blood pressure during daily activities. Three studies tested the hypotheses that: (1) agonistic striving is associated with poor anger regulation, and (2) agonistic striving and poor anger regulation interactively elevate blood pressure. Motivational profiles, anger regulation, and ambulatory blood pressure were assessed in a multiethnic sample of 264 urban youth. (1) anger regulation/recovery during laboratory challenge; (2) anger/blood pressure during daily activities (48 hours). Replication of the profiles in distant cities showed they occur with similar frequency across differences of region, race, and gender. Analyses controlling for body size, race, and gender revealed that individuals with the agonistic striving profile had higher ambulatory pressure, especially during social encounters. They became more openly angry and aggressive when challenged but did not exhibit difficulty regulating anger in the laboratory, nor did they feel angrier during monitoring. However, individuals with the agonistic striving profile who did display poor anger regulation in the lab had the highest blood pressure; deficient self-regulatory capability amplified the positive association between agonistic striving and cardiovascular risk in both genders and all ethnic groups. Although anger is thought to increase cardiovascular risk, present findings suggest that anger and elevated blood pressure are coeffects of agonistic struggles to control others.

Evaluation of peroxisome proliferator-activated receptor agonists on interleukin-5-induced eosinophil differentiation.

PubMed

Smith, Steven G; Hill, Mike; Oliveria, John-Paul; Watson, Brittany M; Baatjes, Adrian J; Dua, Benny; Howie, Karen; Campbell, Heather; Watson, Rick M; Sehmi, Roma; Gauvreau, Gail M

2014-07-01

Peroxisome proliferator-activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin-5 (IL-5) -induced eosinophil differentiation from haemopoietic progenitor cells. Non-adherent mononuclear cells or CD34(+) cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult(®) cultures with IL-5 (10 ng/ml) and IL-3 (25 ng/ml) in the presence of 1-1000 nm PPARα agonist (GW9578), PPARβ/δ agonist (GW501516), PPARγ agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony-forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood-extracted CD34(+) cells cultured with IL-5 or IL-5 + IL-3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm, P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL-5-induced phosphorylation of extracellular signal-regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal-regulated kinase 1/2 signalling pathway. These findings indicate that the PPARγ agonist can attenuate tissue eosinophilia by interfering with local differentiative responses. © 2014 John Wiley & Sons Ltd.

Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

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

Matsushita, Akitomo; Ohtsubo, Sena; Fujita, Tsugumi

Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compoundmore » action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC{sub 50} values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC{sub 50} = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other.« less

Differential effects of antipsychotic and propsychotic drugs on prepulse inhibition and locomotor activity in Roman high- (RHA) and low-avoidance (RLA) rats

PubMed Central

Oliveras, Ignasi; Sánchez-González, Ana; Sampedro-Viana, Daniel; Piludu, Maria Antonietta; Río-Alamos, Cristóbal; Giorgi, Osvaldo; Corda, Maria G.; Aznar, Susana; González-Maeso, Javier; Gerbolés, Cristina; Blázquez, Gloria; Cañete, Toni; Tobeña, Adolf

2017-01-01

Rationale Animal models with predictive and construct validity are necessary for developing novel and efficient therapeutics for psychiatric disorders. Objectives We have carried out a pharmacological characterization of the Roman high-(RHA-I) and low-avoidance (RLA-I) rat strains with different acutely administered propsychotic (DOI, MK-801) and antipsychotic drugs (haloperidol, clozapine), as well as apomorphine, on prepulse inhibition (PPI) of startle and locomotor activity (activity cages). Results RHA-I rats display a consistent deficit of PPI compared with RLA-I rats. The typical antipsychotic haloperidol (dopamine D2 receptor antagonist) reversed the PPI deficit characteristic of RHA-I rats (in particular at 65 and 70 dB prepulse intensities) and reduced locomotion in both strains. The atypical antipsychotic clozapine (serotonin/dopamine receptor antagonist) did not affect PPI in either strain, but decreased locomotion in a dose-dependent manner in both rat strains. The mixed dopamine D1/D2 agonist, apomorphine, at the dose of 0.05 mg/kg, decreased PPI in RHA-I, but not RLA-I rats. The hallucinogen drug DOI (5-HT2A agonist; 0.1–1.0 mg/kg) disrupted PPI in RLA-I rats in a dose-dependent manner at the 70 dB prepulse intensity, while in RHA-Irats, only the 0.5 mg/kg dose impaired PPI at the 80 dB prepulse intensity. DOI slightly decreased locomotion in both strains. Finally, clozapine attenuated the PPI impairment induced by the NMDA receptor antagonist MK-801 only in RLA-I rats. Conclusions These results add experimental evidence to the view that RHA-I rats represent a model with predictive and construct validity of some dopamine and 5-HT2A receptor-related features of schizophrenia. PMID:28154892

Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells

PubMed Central

Sharma, Pawan; Panebra, Alfredo; Pera, Tonio; Tiegs, Brian C.; Hershfeld, Alena; Kenyon, Lawrence C.

2015-01-01

Airway remodeling is a hallmark feature of asthma and chronic obstructive pulmonary disease. Clinical studies and animal models have demonstrated increased airway smooth muscle (ASM) mass, and ASM thickness is correlated with severity of the disease. Current medications control inflammation and reverse airway obstruction effectively but have limited effect on remodeling. Recently we identified the expression of bitter taste receptors (TAS2R) on ASM cells, and activation with known TAS2R agonists resulted in ASM relaxation and bronchodilation. These studies suggest that TAS2R can be used as new therapeutic targets in the treatment of obstructive lung diseases. To further establish their effectiveness, in this study we aimed to determine the effects of TAS2R agonists on ASM growth and promitogenic signaling. Pretreatment of healthy and asthmatic human ASM cells with TAS2R agonists resulted in a dose-dependent inhibition of ASM proliferation. The antimitogenic effect of TAS2R ligands was not dependent on activation of protein kinase A, protein kinase C, or high/intermediate-conductance calcium-activated K+ channels. Immunoblot analyses revealed that TAS2R agonists inhibit growth factor-activated protein kinase B phosphorylation without affecting the availability of phosphatidylinositol 3,4,5-trisphosphate, suggesting TAS2R agonists block signaling downstream of phosphatidylinositol 3-kinase. Furthermore, the antimitogenic effect of TAS2R agonists involved inhibition of induced transcription factors (activator protein-1, signal transducer and activator of transcription-3, E2 factor, nuclear factor of activated T cells) and inhibition of expression of multiple cell cycle regulatory genes, suggesting a direct inhibition of cell cycle progression. Collectively, these findings establish the antimitogenic effect of TAS2R agonists and identify a novel class of receptors and signaling pathways that can be targeted to reduce or prevent airway remodeling as well as

The Good, the Bad, and the Ugly: Agonistic Behaviour in Juvenile Crocodilians

PubMed Central

Brien, Matthew L.; Lang, Jeffrey W.; Webb, Grahame J.; Stevenson, Colin; Christian, Keith A.

2013-01-01

We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5–15 seconds), and occurred between 1600–2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes. PMID:24349018

Structure and biological activity of endogenous and synthetic agonists of GPR119

NASA Astrophysics Data System (ADS)

Tyurenkov, I. N.; Ozerov, A. A.; Kurkin, D. V.; Logvinova, E. O.; Bakulin, D. A.; Volotova, E. V.; Borodin, D. D.

2018-02-01

A G-protein-coupled receptor, GPR119, is a promising pharmacological target for a new class of hypoglycaemic drugs with an original mechanism of action, namely, increase in the glucose-dependent incretin and insulin secretion. In 2005, the first ligands were found and in the subsequent years, a large number of GPR119 agonists were synthesized in laboratories in various countries; the safest and most promising agonists have entered phase I and II clinical trials as agents for the treatment of type 2 diabetes mellitus and obesity. The review describes the major endogenous GPR119 agonists and the main trends in the design and modification of synthetic structures for increasing the hypoglycaemic activity. The data on synthetic agonists are arranged according to the type of the central core of the molecules. The bibliography includes 104 references.

β-Agonist-mediated relaxation of airway smooth muscle is protein kinase A-dependent.

PubMed

Morgan, Sarah J; Deshpande, Deepak A; Tiegs, Brian C; Misior, Anna M; Yan, Huandong; Hershfeld, Alena V; Rich, Thomas C; Panettieri, Reynold A; An, Steven S; Penn, Raymond B

2014-08-15

Inhaled β-agonists are effective at reversing bronchoconstriction in asthma, but the mechanism by which they exert this effect is unclear and controversial. PKA is the historically accepted effector, although this assumption is made on the basis of associative and not direct evidence. Recent studies have asserted that exchange protein activated by cAMP (Epac), not PKA, mediates the relaxation of airway smooth muscle (ASM) observed with β-agonist treatment. This study aims to clarify the role of PKA in the prorelaxant effects of β-agonists on ASM. Inhibition of PKA activity via expression of the PKI and RevAB peptides results in increased β-agonist-mediated cAMP release, abolishes the inhibitory effect of isoproterenol on histamine-induced intracellular calcium flux, and significantly attenuates histamine-stimulated MLC-20 phosphorylation. Analyses of ASM cell and tissue contraction demonstrate that PKA inhibition eliminates most, if not all, β-agonist-mediated relaxation of contracted smooth muscle. Conversely, Epac knockdown had no effect on the regulation of contraction or procontractile signaling by isoproterenol. These findings suggest that PKA, not Epac, is the predominant and physiologically relevant effector through which β-agonists exert their relaxant effects. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Do Agonistic Motives Matter More Than Anger? Three Studies of Cardiovascular Risk in Adolescents

PubMed Central

Ewart, Craig K.; Elder, Gavin J.; Smyth, Joshua M.; Sliwinski, Martin J.; Jorgensen, Randall S.

2011-01-01

Objective Three motivational profiles have been associated with recurring psychological stress in low-income youth and young adults: Striving to control others (agonistic striving), striving to control the self (transcendence striving), and not asserting control (dissipated striving); Agonistic Striving has been associated with elevated ambulatory blood pressure during daily activities. Three studies tested the hypotheses that: (1) Agonistic Striving is associated with poor anger regulation, and (2) Agonistic Striving and poor anger regulation interactively elevate blood pressure. Design Motivational profiles, anger regulation, and ambulatory blood pressure were assessed in a multiethnic sample of 264 urban youth. Main outcome measures (1) Anger regulation/recovery during laboratory challenge; (2) anger / blood pressure during daily activities (48 hours). Results and conclusion Replication of the profiles in distant cities showed they occur with similar frequency across differences of region, race, and gender. Analyses controlling for body size, race, and gender revealed that individuals with the Agonistic Striving profile had higher ambulatory pressure, especially during social encounters. They became more openly angry and aggressive when challenged, but did not exhibit difficulty regulating anger in the laboratory, nor did they feel more angry during monitoring. However, individuals with the Agonistic Striving profile who did display poor anger regulation in the lab had the highest blood pressure; deficient self-regulatory capability amplified the positive association between Agonistic Striving and cardiovascular risk in both genders and all ethnic groups. Although anger is thought to increase cardiovascular risk, present findings suggest that anger and elevated blood pressure are co-effects of agonistic struggles to control others. PMID:21534673

Bitter taste receptor agonists alter mitochondrial function and induce autophagy in airway smooth muscle cells.

PubMed

Pan, Shi; Sharma, Pawan; Shah, Sushrut D; Deshpande, Deepak A

2017-07-01

Airway remodeling, including increased airway smooth muscle (ASM) mass, is a hallmark feature of asthma and COPD. We previously identified the expression of bitter taste receptors (TAS2Rs) on human ASM cells and demonstrated that known TAS2R agonists could promote ASM relaxation and bronchodilation and inhibit mitogen-induced ASM growth. In this study, we explored cellular mechanisms mediating the antimitogenic effect of TAS2R agonists on human ASM cells. Pretreatment of ASM cells with TAS2R agonists chloroquine and quinine resulted in inhibition of cell survival, which was largely reversed by bafilomycin A1, an autophagy inhibitor. Transmission electron microscope studies demonstrated the presence of double-membrane autophagosomes and deformed mitochondria. In ASM cells, TAS2R agonists decreased mitochondrial membrane potential and increased mitochondrial ROS and mitochondrial fragmentation. Inhibiting dynamin-like protein 1 (DLP1) reversed TAS2R agonist-induced mitochondrial membrane potential change and attenuated mitochondrial fragmentation and cell death. Furthermore, the expression of mitochondrial protein BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 (Bnip3) and mitochondrial localization of DLP1 were significantly upregulated by TAS2R agonists. More importantly, inhibiting Bnip3 mitochondrial localization by dominant-negative Bnip3 significantly attenuated cell death induced by TAS2R agonist. Collectively the TAS2R agonists chloroquine and quinine modulate mitochondrial structure and function, resulting in ASM cell death. Furthermore, Bnip3 plays a central role in TAS2R agonist-induced ASM functional changes via a mitochondrial pathway. These findings further establish the cellular mechanisms of antimitogenic effects of TAS2R agonists and identify a novel class of receptors and pathways that can be targeted to mitigate airway remodeling as well as bronchoconstriction in obstructive airway diseases. Copyright © 2017 the American Physiological

Cholecystokinin type B receptor antagonist PD-136,450 is a partial secretory agonist in the stomach and a full agonist in the pancreas of the rat.

PubMed Central

Schmassmann, A; Garner, A; Flogerzi, B; Hasan, M Y; Sanner, M; Varga, L; Halter, F

1994-01-01

Gastrin (cholecystokinin type B (CCK-B)) receptor antagonists may help to elucidate the physiological role of gastrin, have therapeutic potential as acid antisecretory drugs, and may be of use as adjuvant therapy for gastrin sensitive tumours. In binding studies, the gastrin receptor antagonist PD-136,450 had at least 1000 fold greater affinity for gastrin (CCK-B) than CCK-A receptors. In this study the biological activity of PD-136,450 was evaluated in conscious and anaesthetised rats. PD-136,450 antagonised gastrin stimulated acid secretion after subcutaneous (IC50: 0.28 mumol/kg; conscious rats) and intravenous (IC50: 0.17 mumol/kg; anaesthetised rats) administration. In basal secreting fistula animals, the compound stimulated acid output to 30 (5)% of the maximal response to gastrin. Stimulant activity was not caused by gastrin release. As an agonist PD-136,450 was about 350 times less potent than gastrin-17 on a molar basis. In addition, PD-136,450 was a powerful agonist of pancreatic secretion in anaesthetised rats. The specific gastrin antagonist L-365,260 inhibited the (partial) agonist activity of PD-136,450 in the stomach and the specific CCK-A receptor antagonist L-364,718 inhibited the agonist activity of PD-136,450 in the pancreas. It is concluded that the agonist effect of PD-136,450 is mediated via interaction with the gastrin (CCK-B) receptor in the stomach and the CCK-A receptor in the pancreas. PMID:8307482

3D-Pharmacophore Identification for κ-Opioid Agonists Using Ligand-Based Drug-Design Techniques

NASA Astrophysics Data System (ADS)

Yamaotsu, Noriyuki; Hirono, Shuichi

A selective κ-opioid receptor (KOR) agonist might act as a powerful analgesic without the side effects of μ-opioid receptor-selective drugs such as morphine. The eight classes of known KOR agonists have different chemical structures, making it difficult to construct a pharmacophore model that takes them all into account. Here, we summarize previous efforts to identify the pharmacophore for κ-opioid agonists and propose a new three-dimensional pharmacophore model that encompasses the κ-activities of all classes. This utilizes conformational sampling of agonists by high-temperature molecular dynamics and pharmacophore extraction through a series of molecular superpositions.

Dopamine D5 receptor modulates male and female sexual behavior in mice.

PubMed

Kudwa, A E; Dominguez-Salazar, E; Cabrera, D M; Sibley, D R; Rissman, E F

2005-07-01

Dopamine exerts its actions through at least five receptor (DAR) isoforms. In female rats, D5 DAR may be involved in expression of sexual behavior. We used a D5 knockout (D5KO) mouse to assess the role of D5 DAR in mouse sexual behavior. Both sexes of D5KO mice are fertile and exhibit only minor disruptions in exploratory locomotion, startle, and prepulse inhibition responses. This study was conducted to characterize the sexual behavior of male and female D5KO mice relative to their WT littermates. Female WT and D5KO littermates were ovariectomized and given a series of sexual behavior tests after treatment with estradiol benzoate (EB) and progesterone (P). Once sexual performance was optimal the dopamine agonist, apomorphine (APO), was substituted for P. Male mice were observed in pair- and trio- sexual behavior tests. To assess whether the D5 DAR is involved in rewarding aspects of sexual behavior, WT and D5KO male mice were tested for conditioned place preference. Both WT and D5KO females can display receptivity after treatment with EB and P, but APO was only able to facilitate receptivity in EB-primed WT, not in D5KO, mice. Male D5KO mice display normal masculine sexual behavior in mating tests. In conditioned preference tests, WT males formed a conditioned preference for context associated with either intromissions alone or ejaculation as the unconditioned stimulus. In contrast, D5KO males only showed a place preference when ejaculation was paired with the context. In females, the D5 DAR is essential for the actions of dopamine on receptivity. In males, D5 DAR influences rewarding aspects of intromissions. Taken together, the work suggests that the D5 receptor mediates dopamine's action on sexual behavior in both sexes, perhaps via a reward pathway.

Inhibition of 5a-reductase in the nucleus accumbens counters sensorimotor gating deficits induced by dopaminergic activation

PubMed Central

Devoto, Paola; Frau, Roberto; Bini, Valentina; Pillolla, Giuliano; Saba, Pierluigi; Flore, Giovanna; Corona, Marta; Marrosu, Francesco; Bortolato, Marco

2012-01-01

Summary Cogent evidence highlights a key role of neurosteroids and androgens in schizophrenia. We recently reported that inhibition of steroid 5α-reductase (5αR), the rate-limiting enzyme in neurosteroid synthesis and androgen metabolism, elicits antipsychotic-like effects in humans and animal models, without inducing extrapyramidal side effects. To elucidate the anatomical substrates mediating these effects, we investigated the contribution of peripheral and neural structures to the behavioral effects of the 5αR inhibitor finasteride (FIN) on the prepulse inhibition (PPI) of the acoustic startle reflex (ASR), a rat paradigm that dependably simulates the sensorimotor gating impairments observed in schizophrenia and other neuropsychiatric disorders. The potential effect of drug-induced ASR modifications on PPI was excluded by measuring this index both as percent (%PPI) and absolute values (ΔPPI). In both orchidectomized and sham-operated rats, FIN prevented the %PPI deficits induced by the dopamine (DA) receptor agonists apomorphine (APO, 0.25 mg/kg, SC) and d-amphetamine (AMPH, 2.5 mg/kg, SC), although the latter effect was not corroborated by ΔPPI analysis. Conversely, APO-induced PPI deficits were countered by FIN infusions in the brain ventricles (10 μg/1 μl) and in the nucleus accumbens (NAc) shell and core (0.5 μg/0.5 μl/side). No significant PPI-ameliorating effect was observed following FIN injections in other brain regions, including dorsal caudate, basolateral amygdala, ventral hippocampus and medial prefrontal cortex, although a statistical trend was observed for the latter region. The efflux of DA in NAc was increased by systemic, but not intracerebral FIN administration. Taken together, these findings suggest that the role of 5αR in gating regulation is based on post-synaptic mechanisms in the NAc, and is not directly related to alterations in DA efflux in this region. PMID:22029952

The Influence of Teachers&apos; Conceptions on Their Students&apos; Learning: Children&apos;s Understanding of Sheet Music

ERIC Educational Resources Information Center

López-Íñiguez, Guadalupe; Pozo, Juan Ignacio

2014-01-01

Background: Despite increasing interest in teachers&apos; and students&apos; conceptions of learning and teaching, and how they influence their practice, there are few studies testing the influence of teachers&apos; conceptions on their students&apos; learning. Aims: This study tests how teaching conception (TC; with a distinction between…

The glycine transport inhibitor sarcosine is an inhibitory glycine receptor agonist.

PubMed

Zhang, Hai Xia; Lyons-Warren, Ariel; Thio, Liu Lin

2009-01-01

Sarcosine is an endogenous amino acid that is a competitive inhibitor of the type I glycine transporter (GlyT1), an N-methyl-d-aspartate receptor (NMDAR) co-agonist, and an important intermediate in one-carbon metabolism. Its therapeutic potential for schizophrenia further underscores its clinical importance. The structural similarity between sarcosine and glycine and sarcosine's ability to serve as an NMDAR co-agonist led us to examine whether sarcosine is also an agonist at the inhibitory glycine receptor (GlyR). We examined this possibility using whole-cell recordings from cultured embryonic mouse hippocampal neurons and found that sarcosine evoked a dose-dependent, strychnine sensitive, Cl(-) current that cross-inhibited glycine currents. Sarcosine evoked this current with Li(+) in the extracellular solution to block GlyT1, in neurons treated with the essentially irreversible GlyT1 inhibitor N[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine (NFPS), and in neurons plated in the absence of glia. These results indicate that the sarcosine currents did not result from GlyT1 inhibition or heteroexchange. We conclude that sarcosine is a GlyR agonist.

Rodent neurotoxicity bioassays for screening contaminated Great Lakes fish

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

Beattie, M.K.; Hoffman, R.; Gerstenberger, S.

1996-03-01

Standard laboratory rat neurotoxicity protocols were used to study the consequences resulting from the consumption of walleye (Stizostedion vitreum), whitefish (Coregonus clupeaformis), and lake trout (Salvelinus namaycush) from Lake Superior (LS) and the consumption of carp (Cyprinus carpio) from Little Lake Butte des Morte (LLBM) near Oshkosh, Wisconsin, USA. Two 90-d subchronic studies are described, including a 45-d exposure to fish diets using male Sprague-Dawley hooded rats, and a 90-d exposure to fish diets using female rats of the same species. Behavioral alterations were tested using a battery of behavioral tests. In addition, pharmacologic challenges using apomorphine and D-amphetamine weremore » administered to the rats to reveal latent neurotoxic effects. Cumulative fish consumption data were recorded daily, weight gain recorded weekly, and behavior data collected prior to exposure, and on days 7, 14, 55 {+-} 2, 85 {+-} 2. Motor activity data were collected on days 30 {+-} 2, 60 {+-} 2, and 90 {+-} 2 of the feeding protocols. Brain tissue from rodents fed these fish were subsequently analyzed for either mercury (Hg) or polychlorinated biphenyls (PCB). Mercury concentrations were increased in the brains of the walleye-fed rats, and PCB concentrations ranged from 0.5 nl/L to 10 nl/L in the brains of rats fed carp from LLBM, a Lake Michigan tributary. Adult male rats fed LLBM carp for 45 d exhibited the greatest behavior responses to the dopaminergic agonist apomorphine on the accelerating rotarod, although these differences were not significant. The 90-d exposure of LS walleye or Hg-spiked LS walleye resulted in behavior alterations on tactile startle response and second footsplay. D-Amphetamine challenge caused changes in tactile startle response, second footsplay, and accelerating rotarod performance after consuming walleye diets. Rats fed LLBM carp had altered behavioral responses to apomorphine on the accelerating rotarod.« less

Orodispersible sublingual piribedil to abort OFF episodes: a single dose placebo-controlled, randomized, double-blind, cross-over study.

PubMed

Rascol, Olivier; Azulay, Jean-Philippe; Blin, Olivier; Bonnet, Anne-Marie; Brefel-Courbon, Christine; Césaro, Pierre; Damier, Philippe; Debilly, Bérengère; Durif, Frank; Galitzky, Monique; Grouin, Jean-Marie; Pennaforte, Sylvie; Villafane, Gabriel; Yaici, Sadek; Agid, Yves

2010-02-15

S90049, a novel sublingual formulation of the non-ergoline D(2)-D(3) agonist piribedil, has a pharmacokinetic profile promising to provide rapid relief on motor signs in Parkinson's disease (PD). We assessed the efficacy and safety of S90049 in aborting OFF episodes responding to subcutaneous apomorphine in PD patients with motor fluctuations. This was a single-dose double-blind double-placebo 3 x 3 cross-over study. Optimal tested doses were determined during a previous open-label titration phase (S90049 median dose: 60 mg, apomorphine: 5 mg). Primary endpoint was the maximal change versus baseline in UPDRS motor score (Delta UPDRS III) assessed after drug administration following an overnight withdrawal of antiparkinsonian medications. Thirty patients (age: 60 +/- 8 years, PD duration: 12 +/- 6 years, UPDRS III OFF: 37 +/- 15) participated. S90049 was superior to placebo on Delta UPDRS III (-13 +/- 12 versus -7 +/- 9 respectively; estimated difference -5.2, 95% Confidence Interval (CI)[-10.4;0.05], P = 0.05). This was also true for secondary outcomes: number of patients switching from OFF to ON (17 on S90049 vs. 8 on placebo, P = 0.03), time to turn ON (P = 0.013) and duration of the ON phase (P = 0.03). In the 17 patients who switched ON on S90049, Delta UPDRS III was similar on S90049 (-21.2 +/- 10.1) and apomorphine (-23.6 +/- 14.1) (estimated difference: 4.0 95% CI [-2.9;10.9]). S90049 was well tolerated: no serious or unexpected adverse event occurred. A single dose of up to 60 mg of S90049 given sublingually was superior to placebo in improving UPDRS III and aborting a practical OFF in patients with advanced PD. Testing greater doses might improve response rate. (c) 2009 Movement Disorder Society.

Differential profile of typical, atypical and third generation antipsychotics at human 5-HT7a receptors coupled to adenylyl cyclase: detection of agonist and inverse agonist properties.

PubMed

Rauly-Lestienne, Isabelle; Boutet-Robinet, Elisa; Ailhaud, Marie-Christine; Newman-Tancredi, Adrian; Cussac, Didier

2007-10-01

5-HT(7) receptors are present in thalamus and limbic structures, and a possible role of these receptors in the pathology of schizophrenia has been evoked. In this study, we examined binding affinity and agonist/antagonist/inverse agonist properties at these receptors of a large series of antipsychotics, i.e., typical, atypical, and third generation compounds preferentially targeting D(2) and 5-HT(1A) sites. Adenylyl cyclase (AC) activity was measured in HEK293 cells stably expressing the human (h) 5-HT(7a) receptor isoform. 5-HT and 5-CT increased cyclic adenosine monophosphate level by about 20-fold whereas (+)-8-OH-DPAT, the antidyskinetic agent sarizotan, and the novel antipsychotic compound bifeprunox exhibited partial agonist properties at h5-HT(7a) receptors stimulating AC. Other compounds antagonized 5-HT-induced AC activity with pK (B) values which correlated with their pK (i) as determined by competition binding vs [(3)H]5-CT. The selective 5-HT(7) receptor ligand, SB269970, was the most potent antagonist. For antipsychotic compounds, the following rank order of antagonism potency (pK (B)) was ziprasidone > tiospirone > SSR181507 > or = clozapine > or = olanzapine > SLV-314 > SLV-313 > or = aripiprazole > or = chlorpromazine > nemonapride > haloperidol. Interestingly, pretreatment of HEK293-h5-HT(7a) cells with forskolin enhanced basal AC activity and revealed inverse agonist properties for both typical and atypical antipsychotics as well as for aripiprazole. In contrast, other novel antipsychotics exhibited diverse 5-HT(7a) properties; SLV-313 and SLV-314 behaved as quasi-neutral antagonists, SSR181507 acted as an inverse agonist, and bifeprunox as a partial agonist, as mentioned above. In conclusion, the differential properties of third generation antipsychotics at 5-HT(7) receptors may influence their antipsychotic profile.

Platelet-activating factor receptor agonists mediate xeroderma pigmentosum A photosensitivity.

PubMed

Yao, Yongxue; Harrison, Kathleen A; Al-Hassani, Mohammed; Murphy, Robert C; Rezania, Samin; Konger, Raymond L; Travers, Jeffrey B

2012-03-16

To date, oxidized glycerophosphocholines (Ox-GPCs) with platelet-activating factor (PAF) activity produced non-enzymatically have not been definitively demonstrated to mediate any known disease processes. Here we provide evidence that these Ox-GPCs play a pivotal role in the photosensitivity associated with the deficiency of the DNA repair protein xeroderma pigmentosum type A (XPA). It should be noted that XPA-deficient cells are known to have decreased antioxidant defenses. These studies demonstrate that treatment of human XPA-deficient fibroblasts with the pro-oxidative stressor ultraviolet B (UVB) radiation resulted in increased reactive oxygen species and PAF receptor (PAF-R) agonistic activity in comparison with gene-corrected cells. The UVB irradiation-generated PAF-R agonists were inhibited by antioxidants. UVB irradiation of XPA-deficient (Xpa-/-) mice also resulted in increased PAF-R agonistic activity and skin inflammation in comparison with control mice. The increased UVB irradiation-mediated skin inflammation and TNF-α production in Xpa-/- mice were blocked by systemic antioxidants and by PAF-R antagonists. Structural characterization of PAF-R-stimulating activity in UVB-irradiated XPA-deficient fibroblasts using mass spectrometry revealed increased levels of sn-2 short-chain Ox-GPCs along with native PAF. These studies support a critical role for PAF-R agonistic Ox-GPCs in the pathophysiology of XPA photosensitivity.

The therapeutic potential of nicotinic acetylcholine receptor agonists for pain control.

PubMed

Decker, M W; Meyer, M D; Sullivan, J P

2001-10-01

Due to the limitations of currently available analgesics, a number of novel alternatives are currently under investigation, including neuronal nicotinic acetylcholine receptor (nAChR) agonists. During the 1990s, the discovery of the antinociceptive properties of the potent nAChR agonist epibatidine in rodents sparked interest in the analgesic potential of this class of compounds. Although epibatidine also has several mechanism-related toxicities, the identification of considerable nAChR diversity suggested that the toxicities and therapeutic actions of the compound might be mediated by distinct receptor subtypes. Consistent with this view, a number of novel nAChR agonists with antinociceptive activity and improved safety profiles in preclinical models have now been identified, including A-85380, ABT-594, DBO-83, SIB-1663 and RJR-2403. Of these, ABT-594 is the most advanced and is currently in Phase II clinical evaluation. Nicotinically-mediated antinociception has been demonstrated in a variety of rodent pain models and is likely mediated by the activation of descending inhibitory pathways originating in the brainstem with the predominant high-affinity nicotine site in brain, the alpha4beta2 subtype, playing a critical role. Thus, preclinical findings suggest that nAChR agonists have the potential to be highly efficacious treatments in a variety of pain states. However, clinical proof-of-principle studies will be required to determine if nAChR agonists are active in pathological pain.

[Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

PubMed

Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

2014-01-01

Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs.

Comparative gene expression profiles induced by PPAR{gamma} and PPAR{alpha}/{gamma} agonists in rat hepatocytes

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

Rogue, Alexandra; Universite de Rennes 1, 35065 Rennes Cedex; Biologie Servier, 45520 Gidy

2011-07-01

Species-differential toxic effects have been described with PPAR{alpha} and PPAR{gamma} agonists between rodent and human liver. PPAR{alpha} agonists (fibrates) are potent hypocholesterolemic agents in humans while they induce peroxisome proliferation and tumors in rodent liver. By contrast, PPAR{gamma} agonists (glitazones) and even dual PPAR{alpha}/{gamma} agonists (glitazars) have caused idiosyncratic hepatic and nonhepatic toxicities in human without evidence of any damage in rodent during preclinical studies. The mechanisms involved in such differences remain largely unknown. Several studies have identified the major target genes of PPAR{alpha} agonists in rodent liver while no comprehensive analysis has been performed on gene expression changes inducedmore » by PPAR{gamma} and dual PPAR{alpha}/{gamma} agonists. Here, we investigated transcriptomes of rat hepatocytes after 24 h treatment with two PPAR{gamma} (troglitazone and rosiglitazone) and two PPAR{alpha}/{gamma} (muraglitazar and tesaglitazar) agonists. Although, hierarchical clustering revealed a gene expression profile characteristic of each PPAR agonist class, only a limited number of genes was specifically deregulated by glitazars. Functional analyses showed that many genes known as PPAR{alpha} targets were also modulated by both PPAR{gamma} and PPAR{alpha}/{gamma} agonists and quantitative differences in gene expression profiles were observed between these two classes. Moreover, most major genes modulated in rat hepatocytes were also found to be deregulated in rat liver after tesaglitazar treatment. Taken altogether, these results support the conclusion that differential toxic effects of PPAR{alpha} and PPAR{gamma} agonists in rodent liver do not result from transcriptional deregulation of major PPAR target genes but rather from qualitative and/or quantitative differential responses of a small subset of genes.« less

Verticalization of behavior elicited by dopaminergic mobilization is qualitatively different between C57BL/6J and DBA/2J mice.

PubMed

Tirelli, E; Witkin, J M

1994-10-01

Behavioral effects of dopaminergic stimulation were evaluated in C57BL/6J mice and compared to the effects occurring in DBA/2J mice, an inbred strain with reduced densities of striatal dopamine receptors. Effects of apomorphine (0.5-64 mg/kg) alone and in combination with cocaine (30 mg/kg) were assessed using a time-sampling technique that classified climbing and leaning in separate categories. Locomotion was also assessed in a separate experiment. Climbing occurred in DBA/2J mice only at doses of apomorphine that were 16 times higher than the smallest effective dose in C57BL/6J mice; nevertheless, relative to baseline values, effects were fairly comparable. By contrast, whereas DBA/2J mice showed dose-dependent leaning under apomorphine, C57BL/6J mice exhibited little leaning even at doses not producing climbing, and only after the highest apomorphine dose was leaning significantly increased. Apomorphine was equipotent in inducing gnawing across strains, although somewhat less efficacious in DBA/2J mice. When given alone, cocaine produced significant climbing, but not leaning or gnawing, in either strain. Whereas cocaine potentiated apomorphine-induced climbing and gnawing in both strains, apomorphine-induced leaning was not consistently changed by cocaine in either strain. These effects were not indirectly due to hyperkinesia, since neither apomorphine alone nor apomorphine and cocaine in combination was stimulant; apomorphine alone reduced locomotor activity and attenuated cocaine-induced hyperkinesia. The present data do not support a unitary, purely quantitative, account of insensitivity to dopaminergic stimulation based upon low densities of striatal dopamine receptors in DBA/2J mice. Rather, this constellation of results is suggestive of qualitative interstrain dissimilarities in dopaminergic responsiveness that could reflect organizational differences in receptor populations.

Map3k8 Modulates Monocyte State and Atherogenesis in ApoE-/- Mice.

PubMed

Sanz-Garcia, Carlos; Sánchez, Ángela; Contreras-Jurado, Constanza; Cales, Carmela; Barranquero, Cristina; Muñoz, Marta; Merino, Ramón; Escudero, Paula; Sanz, Maria-Jesús; Osada, Jesús; Aranda, Ana; Alemany, Susana

2017-02-01

Map3k8 (Cot/Tpl2) activates the MKK1/2-ERK1/2, MAPK pathway downstream from interleukin-1R, tumor necrosis factor-αR, NOD-2R (nucleotide-binding oligomerization domain-like 2R), adiponectinR, and Toll-like receptors. Map3k8 plays a key role in innate and adaptive immunity and influences inflammatory processes by modulating the functions of different cell types. However, its role in atherogenesis remains unknown. In this study, we analyzed the role of this kinase in this pathology. We show here that Map3k8 deficiency results in smaller numbers of Ly6C high CD11c low and Ly6C low CD11c high monocytes in ApoE - /- mice fed a high-fat diet (HFD). Map3k8 -/- ApoE -/- monocytes displayed high rates of apoptosis and reduced amounts of Nr4a1, a transcription factor known to modulate apoptosis in Ly6C low CD11c high monocytes. Map3k8 -/- ApoE -/- splenocytes and macrophages showed irregular patterns of cytokine and chemokine expression. Map3k8 deficiency altered cell adhesion and migration in vivo and decreased CCR2 expression, a determinant chemokine receptor for monocyte mobilization, on circulating Ly6C high CD11c low monocytes. Map3k8 -/- ApoE -/- mice fed an HFD showed decreased cellular infiltration in the atherosclerotic plaque, with low lipid content. Lesions had similar size after Map3k8 +/+ ApoE -/- bone marrow transplant into Map3k8 -/- ApoE -/- and Map3k8 +/+ ApoE -/- mice fed an HFD, whereas smaller plaques were observed after the transplantation of bone marrow lacking both ApoE and Map3k8. Map3k8 decreases apoptosis of monocytes and enhances CCR2 expression on Ly6C high CD11c low monocytes of ApoE -/- mice fed an HFD. These findings explain the smaller aortic lesions in ApoE -/- mice with Map3k8 -/- ApoE -/- bone marrow cells fed an HFD, supporting further studies of Map3k8 as an antiatherosclerotic target. © 2016 American Heart Association, Inc.

The Role of Agonistic Striving in the Association Between Cortisol and High Blood Pressure.

PubMed

Ewart, Craig K; Elder, Gavin J; Jorgensen, Randall S; Fitzgerald, Sheila T

2017-05-01

A social action theory of chronic stress proposes that agonistic striving (seeking to influence or control others) impairs cardiovascular health by magnifying the impact of high adversity-induced cortisol levels on blood pressure. We tested three predictions of social action theory: (1) the social action theory taxonomy of regulatory strivings characterizes young adults from high-adversity neighborhoods; (2) high cortisol levels predict high blood pressure more reliably in the subgroup with the agonistic striving profile than in subgroups with other profiles; (3) the association of higher cortisol and higher blood pressure with agonistic striving is not explained by negative affect (depressive symptoms/dysphoria, anger, hostility). Participants were young adults (N = 198, mean [SD] age = 32 [3.4] years); 71% female; 65% black) from disadvantaged urban neighborhoods. Motive profiles (including agonistic strivings) were assessed using the Social Competence Interview. Cortisol levels were derived from saliva samples; blood pressure level was obtained during two days of ambulatory monitoring. Psychological measures of negative affect were assessed using questionnaires. The predicted taxonomy of regulatory strivings was replicated in this sample; the interaction between cortisol and motive profile was significant (F(2, 91) = 6.72, p = .002); analyses of simple effects disclosed that higher cortisol levels predicted higher ambulatory blood pressure only in individuals who exhibited agonistic striving. Depressive symptoms/dysphoria, trait anger, and hostility were not correlated with agonistic striving, cortisol, or blood pressure. Agonistic striving may represent a distinctive (and novel) social-cognitive mechanism of toxic stress and cardiovascular risk.

Determination of beta-agonists in swine hair by μFIA and chemiluminescence.

PubMed

Chen, Xu; Luo, Yong; Shi, Bo; Gao, Zhigang; Du, Yuguang; Liu, Xianming; Zhao, Weijie; Lin, Bingcheng

2015-04-01

β-Agonists are a group of illegal feed additives. In this paper, it was found that the light emission produced by the oxidation of luminol by potassium ferricyanide was enhanced by the β-agonists (ractopamine, salbutamol, and terbutaline). Based on chemiluminescence phenomenon, a novel, rapid, and sensitive microflow injection analysis system on a microfluidic glass chip was established for determination of the β-agonists. The chip was fabricated from two glass plates (64 mm × 32 mm) with microchannels of 200 μm width and 100 μm depth. The detection limits were achieved at 2.0 × 10(-8) mol/L of ractopamine, 1.0 × 10(-8) mol/L of terbutaline and 5.0 × 10(-7) mol/L of salbutamol. In this report, our method was applied for determination of the β-agonists in swine hair from three different sources with satisfactory results. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preclinical evaluation of SMM-189, a cannabinoid receptor 2-specific inverse agonist.

PubMed

Presley, Chaela; Abidi, Ammaar; Suryawanshi, Satyendra; Mustafa, Suni; Meibohm, Bernd; Moore, Bob M

2015-08-01

Cannabinoid receptor 2 agonists and inverse agonists are emerging as new therapeutic options for a spectrum of autoimmune-related disease. Of particular interest, is the ability of CB2 ligands to regulate microglia function in neurodegenerative diseases and traumatic brain injury. We have previously reported the receptor affinity of 3',5'-dichloro-2,6-dihydroxy-biphenyl-4-yl)-phenyl-methanone (SMM-189) and the characterization of the beneficial effects of SMM-189 in the mouse model of mild traumatic brain injury. Herein, we report the further characterization of SMM-189 as a potent and selective CB2 inverse agonist, which acts as a noncompetitive inhibitor of CP 55,940. The ability of SMM-189 to regulate microglial activation, in terms of chemokine expression and cell morphology, has been determined. Finally, we have determined that SMM-189 possesses acceptable biopharmaceutical properties indicating that the triaryl class of CB2 inverse agonists are viable compounds for continued preclinical development for the treatment of neurodegenerative disorders and traumatic brain injury.

Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells.

PubMed

Sharma, Pawan; Panebra, Alfredo; Pera, Tonio; Tiegs, Brian C; Hershfeld, Alena; Kenyon, Lawrence C; Deshpande, Deepak A

2016-02-15

Airway remodeling is a hallmark feature of asthma and chronic obstructive pulmonary disease. Clinical studies and animal models have demonstrated increased airway smooth muscle (ASM) mass, and ASM thickness is correlated with severity of the disease. Current medications control inflammation and reverse airway obstruction effectively but have limited effect on remodeling. Recently we identified the expression of bitter taste receptors (TAS2R) on ASM cells, and activation with known TAS2R agonists resulted in ASM relaxation and bronchodilation. These studies suggest that TAS2R can be used as new therapeutic targets in the treatment of obstructive lung diseases. To further establish their effectiveness, in this study we aimed to determine the effects of TAS2R agonists on ASM growth and promitogenic signaling. Pretreatment of healthy and asthmatic human ASM cells with TAS2R agonists resulted in a dose-dependent inhibition of ASM proliferation. The antimitogenic effect of TAS2R ligands was not dependent on activation of protein kinase A, protein kinase C, or high/intermediate-conductance calcium-activated K(+) channels. Immunoblot analyses revealed that TAS2R agonists inhibit growth factor-activated protein kinase B phosphorylation without affecting the availability of phosphatidylinositol 3,4,5-trisphosphate, suggesting TAS2R agonists block signaling downstream of phosphatidylinositol 3-kinase. Furthermore, the antimitogenic effect of TAS2R agonists involved inhibition of induced transcription factors (activator protein-1, signal transducer and activator of transcription-3, E2 factor, nuclear factor of activated T cells) and inhibition of expression of multiple cell cycle regulatory genes, suggesting a direct inhibition of cell cycle progression. Collectively, these findings establish the antimitogenic effect of TAS2R agonists and identify a novel class of receptors and signaling pathways that can be targeted to reduce or prevent airway remodeling as well as

Effects of oxytocin on serotonin 1B agonist-induced autism-like behavior in mice.

PubMed

Lawson, Sarah K; Gray, Andrew C; Woehrle, Nancy S

2016-11-01

Social impairments in autism remain poorly understood and without approved pharmacotherapies. Novel animals models are needed to elucidate mechanisms and evaluate novel treatments for the social deficits in autism. Recently, serotonin 1B receptor (5-HT1B) agonist challenge in mice was shown to induce autism-like behaviors including perseveration, reduced prepulse inhibition, and delayed alternation deficits. However, the effects of 5-HT1B agonists on autism-related social behaviors in mice remain unknown. Here, we examine the effects of 5-HT1B agonist challenge on sociability and preference for social novelty in mice. We also examine the effects of 5-HT1B agonist treatment on average rearing duration, a putative rodent measure of non-selective attention. Non-selective attention is an associated feature of autism that is also not well understood. We show that 5-HT1B receptor activation reduces sociability, preference for social novelty, and rearing in mice. In addition, we examine the ability of oxytocin, an off-label treatment for the social impairments in autism, to reverse 5-HT1B agonist-induced social and attention deficits in mice. We show that oxytocin restores social novelty preference in mice treated with a 5-HT1B agonist. We also show that oxytocin attenuates 5-HT1B agonist-induced sociability and rearing deficits in mice. Our results suggest that 5-HT1B agonist challenge provides a useful pharmacological mouse model for aspects of autism, and implicate 5-HT1B in autism social and attention deficits. Moreover, our findings suggest that oxytocin may treat the social deficits in autism through a mechanism involving 5-HT1B. Copyright © 2016 Elsevier B.V. All rights reserved.

Systematic review: cardiovascular safety profile of 5-HT(4) agonists developed for gastrointestinal disorders.

PubMed

Tack, J; Camilleri, M; Chang, L; Chey, W D; Galligan, J J; Lacy, B E; Müller-Lissner, S; Quigley, E M M; Schuurkes, J; De Maeyer, J H; Stanghellini, V

2012-04-01

The nonselective 5-HT(4) receptor agonists, cisapride and tegaserod have been associated with cardiovascular adverse events (AEs). To perform a systematic review of the safety profile, particularly cardiovascular, of 5-HT(4) agonists developed for gastrointestinal disorders, and a nonsystematic summary of their pharmacology and clinical efficacy. Articles reporting data on cisapride, clebopride, prucalopride, mosapride, renzapride, tegaserod, TD-5108 (velusetrag) and ATI-7505 (naronapride) were identified through a systematic search of the Cochrane Library, Medline, Embase and Toxfile. Abstracts from UEGW 2006-2008 and DDW 2008-2010 were searched for these drug names, and pharmaceutical companies approached to provide unpublished data. Retrieved articles on pharmacokinetics, human pharmacodynamics and clinical data with these 5-HT(4) agonists, are reviewed and summarised nonsystematically. Articles relating to cardiac safety and tolerability of these agents, including any relevant case reports, are reported systematically. Two nonselective 5-HT(4) agonists had reports of cardiovascular AEs: cisapride (QT prolongation) and tegaserod (ischaemia). Interactions with, respectively, the hERG cardiac potassium channel and 5-HT(1) receptor subtypes have been suggested to account for these effects. No cardiovascular safety concerns were reported for the newer, selective 5-HT(4) agonists prucalopride, velusetrag, naronapride, or for nonselective 5-HT(4) agonists with no hERG or 5-HT(1) affinity (renzapride, clebopride, mosapride). 5-HT(4) agonists for GI disorders differ in chemical structure and selectivity for 5-HT(4) receptors. Selectivity for 5-HT(4) over non-5-HT(4) receptors may influence the agent's safety and overall risk-benefit profile. Based on available evidence, highly selective 5-HT(4) agonists may offer improved safety to treat patients with impaired GI motility. © 2012 Blackwell Publishing Ltd.

Systematic review: cardiovascular safety profile of 5-HT4 agonists developed for gastrointestinal disorders

PubMed Central

Tack, J; Camilleri, M; Chang, L; Chey, W D; Galligan, J J; Lacy, B E; Müller-Lissner, S; Quigley, E M M; Schuurkes, J; Maeyer, J H; Stanghellini, V

2012-01-01

Summary Background The nonselective 5-HT4 receptor agonists, cisapride and tegaserod have been associated with cardiovascular adverse events (AEs). Aim To perform a systematic review of the safety profile, particularly cardiovascular, of 5-HT4 agonists developed for gastrointestinal disorders, and a nonsystematic summary of their pharmacology and clinical efficacy. Methods Articles reporting data on cisapride, clebopride, prucalopride, mosapride, renzapride, tegaserod, TD-5108 (velusetrag) and ATI-7505 (naronapride) were identified through a systematic search of the Cochrane Library, Medline, Embase and Toxfile. Abstracts from UEGW 2006–2008 and DDW 2008–2010 were searched for these drug names, and pharmaceutical companies approached to provide unpublished data. Results Retrieved articles on pharmacokinetics, human pharmacodynamics and clinical data with these 5-HT4 agonists, are reviewed and summarised nonsystematically. Articles relating to cardiac safety and tolerability of these agents, including any relevant case reports, are reported systematically. Two nonselective 5-HT4 agonists had reports of cardiovascular AEs: cisapride (QT prolongation) and tegaserod (ischaemia). Interactions with, respectively, the hERG cardiac potassium channel and 5-HT1 receptor subtypes have been suggested to account for these effects. No cardiovascular safety concerns were reported for the newer, selective 5-HT4 agonists prucalopride, velusetrag, naronapride, or for nonselective 5-HT4 agonists with no hERG or 5-HT1 affinity (renzapride, clebopride, mosapride). Conclusions 5-HT4 agonists for GI disorders differ in chemical structure and selectivity for 5-HT4 receptors. Selectivity for 5-HT4 over non-5-HT4 receptors may influence the agent's safety and overall risk–benefit profile. Based on available evidence, highly selective 5-HT4 agonists may offer improved safety to treat patients with impaired GI motility. PMID:22356640

Beta2-adrenoceptor agonists for dysmenorrhoea.

PubMed

Fedorowicz, Zbys; Nasser, Mona; Jagannath, Vanitha A; Beaman, Jessica H; Ejaz, Kiran; van Zuuren, Esther J

2012-05-16

Dysmenorrhoea is a common gynaecological complaint that can affect as many as 50% of premenopausal women, 10% of whom suffer severely enough to be rendered incapacitated for one to three days during each menstrual cycle. Primary dysmenorrhoea is where women suffer from menstrual pain but lack any pathology in their pelvic anatomy. Beta2-adrenoceptor agonists have been used in the treatment of women with primary dysmenorrhoea but their effects are unclear. To determine the effectiveness and safety of beta2-adrenoceptor agonists in the treatment of primary dysmenorrhoea. We searched the Cochrane Menstrual Disorders and Subfertility Group Specialised Register; CENTRAL (The Cochrane Library 2011, Issue 8); MEDLINE; EMBASE; PsycINFO and the EBM Reviews databases. The last search was on 22 August 2011. Randomised controlled trials comparing beta2-adrenoceptor agonists with placebo or no treatment, each other or any other conventional treatment in women of reproductive age with primary dysmenorrhoea. Two review authors independently assessed trial quality and extracted the data. Five trials involving 187 women with an age range of 15 to 40 years were included. Oral isoxsuprine was compared with placebo in two trials; terbutaline oral spray, ritodrine chloride and oral hydroxyphenyl-orciprenalin were compared with placebo in a further three trials. Clinical diversity in the studies in terms of the interventions being evaluated, assessments at different time points and the use of different assessment tools mitigated against pooling of outcome data across studies in order to provide a summary estimate of effect for any of the comparisons. Only one study, with unclear risk of bias, reported pain relief with a combination of isoxsuprine, acetaminophen and caffeine. None of the other studies reported any significant clinical difference in effectiveness between the intervention and placebo. Adverse effects were reported with all of these medications in up to a quarter of the

Targeting GLP-1 receptor trafficking to improve agonist efficacy.

PubMed

Jones, Ben; Buenaventura, Teresa; Kanda, Nisha; Chabosseau, Pauline; Owen, Bryn M; Scott, Rebecca; Goldin, Robert; Angkathunyakul, Napat; Corrêa, Ivan R; Bosco, Domenico; Johnson, Paul R; Piemonti, Lorenzo; Marchetti, Piero; Shapiro, A M James; Cochran, Blake J; Hanyaloglu, Aylin C; Inoue, Asuka; Tan, Tricia; Rutter, Guy A; Tomas, Alejandra; Bloom, Stephen R

2018-04-23

Glucagon-like peptide-1 receptor (GLP-1R) activation promotes insulin secretion from pancreatic beta cells, causes weight loss, and is an important pharmacological target in type 2 diabetes (T2D). Like other G protein-coupled receptors, the GLP-1R undergoes agonist-mediated endocytosis, but the functional and therapeutic consequences of modulating GLP-1R endocytic trafficking have not been clearly defined. Here, we investigate a series of biased GLP-1R agonists with variable propensities for GLP-1R internalization and recycling. Compared to a panel of FDA-approved GLP-1 mimetics, compounds that retain GLP-1R at the plasma membrane produce greater long-term insulin release, which is dependent on a reduction in β-arrestin recruitment and faster agonist dissociation rates. Such molecules elicit glycemic benefits in mice without concomitant increases in signs of nausea, a common side effect of GLP-1 therapies. Our study identifies a set of agents with specific GLP-1R trafficking profiles and the potential for greater efficacy and tolerability as T2D treatments.

Peroxidative metabolism of beta2-agonists salbutamol and fenoterol and their analogues.

PubMed

Reszka, Krzysztof J; McGraw, Dennis W; Britigan, Bradley E

2009-06-01

Phenolic beta(2)-adrenoreceptor agonists salbutamol, fenoterol, and terbutaline relax smooth muscle cells that relieve acute airway bronchospasm associated with asthma. Why their use sometimes fails to relieve bronchospasm and why the drugs appear to be less effective in patients with severe asthma exacerbations remains unclear. We show that in the presence of hydrogen peroxide, both myeloperoxidase, secreted by activated neutrophils present in inflamed airways, and lactoperoxidase, which is naturally present in the respiratory system, catalyze oxidation of these beta(2)-agonists. Azide, cyanide, thiocyanate, ascorbate, glutathione, and methimazole inhibited this process, while methionine was without effect. Inhibition by ascorbate and glutathione was associated with their oxidation to corresponding radical species by the agonists' derived phenoxyl radicals. Using electron paramagnetic resonance (EPR), we detected free radical metabolites from beta(2)-agonists by spin trapping with 2-methyl-2-nitrosopropane (MNP). Formation of these radicals was inhibited by pharmacologically relevant concentrations of methimazole and dapsone. In alkaline buffers, radicals from fenoterol and its structural analogue, metaproteronol, were detected by direct EPR. Analysis of these spectra suggests that oxidation of fenoterol and metaproterenol, but not terbutaline, causes their transformation through intramolecular cyclization by addition of their amino nitrogen to the aromatic ring. Together, these results indicate that phenolic beta(2)-agonists function as substrates for airway peroxidases and that the resulting products differ in their structural and functional properties from their parent compounds. They also suggest that these transformations can be modulated by pharmacological approaches using appropriate peroxidase inhibitors or alternative substrates. These processes may affect therapeutic efficacy and also play a role in adverse reactions of the beta(2)-agonists.

NOP Receptor Mediates Anti-analgesia Induced by Agonist-Antagonist Opioids

PubMed Central

Gear, Robert W.; Bogen, Oliver; Ferrari, Luiz F.; Green, Paul G.; Levine, Jon D.

2014-01-01

Clinical studies have shown that agonist-antagonist opioid analgesics that produce their analgesic effect via action on the kappa-opioid receptor, produce a delayed-onset anti-analgesia in men but not women, an effect blocked by co-administration of a low dose of naloxone. We now report the same time-dependent anti-analgesia and its underlying mechanism in an animal model. Using the Randall-Selitto paw-withdrawal assay in male rats, we found that nalbuphine, pentazocine, and butorphanol each produced analgesia during the first hour followed by anti-analgesia starting at ~90 minutes after administration in males but not females, closely mimicking its clinical effects. As observed in humans, co-administration of nalbuphine with naloxone in a dose ratio of 12.5:1 blocked anti-analgesia but not analgesia. Administration of the highly selective kappa-opioid receptor agonist U69,593 produced analgesia without subsequent anti-analgesia, and confirmed by the failure of the selective kappa antagonist nor-binaltorphimine to block nalbuphine-induced anti-analgesia, indicating that anti-analgesia is not mediated by kappa-opioid receptors. We therefore tested the role of other receptors in nalbuphine anti-analgesia. Nociceptin/orphanin FQ (NOP) and sigma-1 and sigma-2 receptors were chosen on the basis of their known anti-analgesic effects and receptor binding studies. The selective NOP receptor antagonists, JTC801, and J113397, but not the sigma receptor antagonist, BD 1047, antagonized nalbuphine anti-analgesia. Furthermore, the NOP receptor agonist NNC 63-0532 produced anti-analgesia with the same delay in onset observed with the three agonist-antagonists, but without producing preceding analgesia and this anti-analgesia was also blocked by naloxone. These results strongly support the suggestion that clinically used agonist-antagonists act at the NOP receptor to produce anti-analgesia. PMID:24188792

Progesterone receptor isoforms, agonists and antagonists differentially reprogram estrogen signaling

PubMed Central

Singhal, Hari; Greene, Marianne E.; Zarnke, Allison L.; Laine, Muriel; Al Abosy, Rose; Chang, Ya-Fang; Dembo, Anna G.; Schoenfelt, Kelly; Vadhi, Raga; Qiu, Xintao; Rao, Prakash; Santhamma, Bindu; Nair, Hareesh B.; Nickisch, Klaus J.; Long, Henry W.; Becker, Lev; Brown, Myles; Greene, Geoffrey L.

2018-01-01

Major roadblocks to developing effective progesterone receptor (PR)-targeted therapies in breast cancer include the lack of highly-specific PR modulators, a poor understanding of the pro- or anti-tumorigenic networks for PR isoforms and ligands, and an incomplete understanding of the cross talk between PR and estrogen receptor (ER) signaling. Through genomic analyses of xenografts treated with various clinically-relevant ER and PR-targeting drugs, we describe how the activation or inhibition of PR differentially reprograms estrogen signaling, resulting in the segregation of transcriptomes into separate PR agonist and antagonist-mediated groups. These findings address an ongoing controversy regarding the clinical utility of PR agonists and antagonists, alone or in combination with tamoxifen, for breast cancer management. Additionally, the two PR isoforms PRA and PRB, bind distinct but overlapping genomic sites and interact with different sets of co-regulators to differentially modulate estrogen signaling to be either pro- or anti-tumorigenic. Of the two isoforms, PRA inhibited gene expression and ER chromatin binding significantly more than PRB. Differential gene expression was observed in PRA and PRB-rich patient tumors and PRA-rich gene signatures had poorer survival outcomes. In support of antiprogestin responsiveness of PRA-rich tumors, gene signatures associated with PR antagonists, but not PR agonists, predicted better survival outcomes. The better patient survival associated with PR antagonists versus PR agonists treatments was further reflected in the higher in vivo anti-tumor activity of therapies that combine tamoxifen with PR antagonists and modulators. This study suggests that distinguishing common effects observed due to concomitant interaction of another receptor with its ligand (agonist or antagonist), from unique isoform and ligand-specific effects will inform the development of biomarkers for patient selection and translation of PR

The convulsive and electroencephalographic changes produced by nonpeptidic delta-opioid agonists in rats: comparison with pentylenetetrazol.

PubMed

Jutkiewicz, Emily M; Baladi, Michelle G; Folk, John E; Rice, Kenner C; Woods, James H

2006-06-01

delta-Opioid agonists produce convulsions and antidepressant-like effects in rats. It has been suggested that the antidepressant-like effects are produced through a convulsant mechanism of action either through overt convulsions or nonconvulsive seizures. This study evaluated the convulsive and seizurogenic effects of nonpeptidic delta-opioid agonists at doses that previously were reported to produce antidepressant-like effects. In addition, delta-opioid agonist-induced electroencephalographic (EEG) and behavioral changes were compared with those produced by the chemical convulsant pentylenetetrazol (PTZ). For these studies, EEG changes were recorded using a telemetry system before and after injections of the delta-opioid agonists [(+)-4-[(alphaR)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)methyl]-N,N-diethylbenz (SNC80) and [(+)-4-[alpha(R)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide [(+)-BW373U86]. Acute administration of nonpeptidic delta-opioid agonists produced bilateral ictal and paroxysmal spike and/or sharp wave discharges. delta-Opioid agonists produced brief changes in EEG recordings, and tolerance rapidly developed to these effects; however, PTZ produced longer-lasting EEG changes that were exacerbated after repeated administration. Studies with antiepileptic drugs demonstrated that compounds used to treat absence epilepsy blocked the convulsive effects of nonpeptidic delta-opioid agonists. Overall, these data suggest that delta-opioid agonist-induced EEG changes are not required for the antidepressant-like effects of these compounds and that neural circuitry involved in absence epilepsy may be related to delta-opioid agonist-induced convulsions. In terms of therapeutic development, these data suggest that it may be possible to develop delta-opioid agonists devoid of convulsive properties.

The Glycine Transport Inhibitor Sarcosine Is an Inhibitory Glycine Receptor Agonist

PubMed Central

Zhang, Hai Xia; Lyons-Warren, Ariel; Thio, Liu Lin

2009-01-01

Summary Sarcosine is an endogenous amino acid that is a competitive inhibitor of the type I glycine transporter (GlyT1), an N-methyl-D-aspartate receptor (NMDAR) co-agonist, and an important intermediate in one-carbon metabolism. Its therapeutic potential for schizophrenia further underscores its clinical importance. The structural similarity between sarcosine and glycine and sarcosine's ability to serve as an NMDAR co-agonist led us to examine whether sarcosine is also an agonist at the inhibitory glycine receptor (GlyR). We examined this possibility using whole-cell recordings from cultured embryonic mouse hippocampal neurons and found that sarcosine evoked a dose-dependent, strychnine sensitive, Cl- current that cross-inhibited glycine currents. Sarcosine evoked this current with Li+ in the extracellular solution to block GlyT1, in neurons treated with the essentially irreversible GlyT1 inhibitor N[3-(4′-fluorophenyl)-3-(4′-phenylphenoxy)propyl]sarcosine (NFPS), and in neurons plated in the absence of glia. These results indicate that the sarcosine currents did not result from GlyT1 inhibition or heteroexchange. We conclude that sarcosine is a GlyR agonist. PMID:19619564

PPAR agonists regulate brain gene expression: relationship to their effects on ethanol consumption.

PubMed

Ferguson, Laura B; Most, Dana; Blednov, Yuri A; Harris, R Adron

2014-11-01

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that act as ligand-activated transcription factors. Although prescribed for dyslipidemia and type-II diabetes, PPAR agonists also possess anti-addictive characteristics. PPAR agonists decrease ethanol consumption and reduce withdrawal severity and susceptibility to stress-induced relapse in rodents. However, the cellular and molecular mechanisms facilitating these properties have yet to be investigated. We tested three PPAR agonists in a continuous access two-bottle choice (2BC) drinking paradigm and found that tesaglitazar (PPARα/γ; 1.5 mg/kg) and fenofibrate (PPARα; 150 mg/kg) decreased ethanol consumption in male C57BL/6J mice while bezafibrate (PPARα/γ/β; 75 mg/kg) did not. We hypothesized that changes in brain gene expression following fenofibrate and tesaglitazar treatment lead to reduced ethanol drinking. We studied unbiased genomic profiles in areas of the brain known to be important for ethanol dependence, the prefrontal cortex (PFC) and amygdala, and also profiled gene expression in liver. Genomic profiles from the non-effective bezafibrate treatment were used to filter out genes not associated with ethanol consumption. Because PPAR agonists are anti-inflammatory, they would be expected to target microglia and astrocytes. Surprisingly, PPAR agonists produced a strong neuronal signature in mouse brain, and fenofibrate and tesaglitazar (but not bezafibrate) targeted a subset of GABAergic interneurons in the amygdala. Weighted gene co-expression network analysis (WGCNA) revealed co-expression of treatment-significant genes. Functional annotation of these gene networks suggested that PPAR agonists might act via neuropeptide and dopaminergic signaling pathways in the amygdala. Our results reveal gene targets through which PPAR agonists can affect alcohol consumption behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

RNA-Seq Mouse Brain Regions Expression Data Analysis: Focus on ApoE Functional Network

PubMed

Babenko, Vladimir N; Smagin, Dmitry A; Kudryavtseva, Natalia N

2017-09-13

ApoE expression status was proved to be a highly specific marker of energy metabolism rate in the brain. Along with its neighbor, Translocase of Outer Mitochondrial Membrane 40 kDa (TOMM40) which is involved in mitochondrial metabolism, the corresponding genomic region constitutes the neuroenergetic hotspot. Using RNA-Seq data from a murine model of chronic stress a significant positive expression coordination of seven neighboring genes in ApoE locus in five brain regions was observed. ApoE maintains one of the highest absolute expression values genome-wide, implying that ApoE can be the driver of the neighboring gene expression alteration observed under stressful loads. Notably, we revealed the highly statistically significant increase of ApoE expression in the hypothalamus of chronically aggressive (FDR < 0.007) and defeated (FDR < 0.001) mice compared to the control. Correlation analysis revealed a close association of ApoE and proopiomelanocortin (Pomc) gene expression profiles implying the putative neuroendocrine stress response background of ApoE expression elevation therein.

Suppression of atherosclerosis by synthetic REV-ERB agonist

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

Sitaula, Sadichha; Billon, Cyrielle; Kamenecka, Theodore M.

2015-05-08

The nuclear receptors for heme, REV-ERBα and REV-ERBβ, play important roles in the regulation of metabolism and inflammation. Recently it was demonstrated that reduced REV-ERBα expression in hematopoetic cells in LDL receptor null mice led to increased atherosclerosis. We sought to determine if synthetic REV-ERB agonists that we have developed might have the ability to suppress atherosclerosis in this model. A previously characterized synthetic REV-ERB agonist, SR9009, was used to determine if activation of REV-ERB activity would affect atherosclerosis in LDL receptor deficient mice. Atherosclerotic plaque size was significantly reduced (p < 0.05) in mice administered SR9009 (100 mg/kg) for seven weeks comparedmore » to control mice (n = 10 per group). SR9009 treatment of bone marrow-derived mouse macrophages (BMDM) reduced the polarization of BMDMs to proinflammatory M1 macrophage while increasing the polarization of BMDMs to anti-inflammatory M2 macrophages. Our results suggest that pharmacological targeting of REV-ERBs may be a viable therapeutic option for treatment of atherosclerosis. - Highlights: • Synthetic REV-ERB agonist treatment reduced atherosclerosis in a mouse model. • Pharmacological activation of REV-ERB decreased M1 macrophage polarization. • Pharmacological activation of REV-ERB increased M2 macrophage polarization.« less

Post Hoc Analyses of ApoE Genotype-Defined Subgroups in Clinical Trials.

PubMed

Kennedy, Richard E; Cutter, Gary R; Wang, Guoqiao; Schneider, Lon S

2016-01-01

Many post hoc analyses of clinical trials in Alzheimer's disease (AD) and mild cognitive impairment (MCI) are in small Phase 2 trials. Subject heterogeneity may lead to statistically significant post hoc results that cannot be replicated in larger follow-up studies. We investigated the extent of this problem using simulation studies mimicking current trial methods with post hoc analyses based on ApoE4 carrier status. We used a meta-database of 24 studies, including 3,574 subjects with mild AD and 1,171 subjects with MCI/prodromal AD, to simulate clinical trial scenarios. Post hoc analyses examined if rates of progression on the Alzheimer's Disease Assessment Scale-cognitive (ADAS-cog) differed between ApoE4 carriers and non-carriers. Across studies, ApoE4 carriers were younger and had lower baseline scores, greater rates of progression, and greater variability on the ADAS-cog. Up to 18% of post hoc analyses for 18-month trials in AD showed greater rates of progression for ApoE4 non-carriers that were statistically significant but unlikely to be confirmed in follow-up studies. The frequency of erroneous conclusions dropped below 3% with trials of 100 subjects per arm. In MCI, rates of statistically significant differences with greater progression in ApoE4 non-carriers remained below 3% unless sample sizes were below 25 subjects per arm. Statistically significant differences for ApoE4 in post hoc analyses often reflect heterogeneity among small samples rather than true differential effect among ApoE4 subtypes. Such analyses must be viewed cautiously. ApoE genotype should be incorporated into the design stage to minimize erroneous conclusions.

Pharmacological characterization of ATPM [(-)-3-aminothiazolo[5,4-b]-N-cyclopropylmethylmorphinan hydrochloride], a novel mixed kappa-agonist and mu-agonist/-antagonist that attenuates morphine antinociceptive tolerance and heroin self-administration behavior.

PubMed

Wang, Yu-Jun; Tao, Yi-Min; Li, Fu-Ying; Wang, Yu-Hua; Xu, Xue-Jun; Chen, Jie; Cao, Ying-Lin; Chi, Zhi-Qiang; Neumeyer, John L; Zhang, Ao; Liu, Jing-Gen

2009-04-01

ATPM [(-)-3-amino-thiazolo[5,4-b]-N-cyclopropylmethylmorphinan hydrochloride] was found to have mixed kappa- and mu-opioid activity and identified to act as a full kappa-agonist and a partial mu-agonist by in vitro binding assays. The present study was undertaken to characterize its in vivo effects on morphine antinociceptive tolerance in mice and heroin self-administration in rats. ATPM was demonstrated to yield more potent antinociceptive effects than (-)U50,488H (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide). It was further found that the antinociceptive effects of ATPM were mediated by kappa- and mu-, but not delta-opioid, receptors. In addition to its agonist profile on the mu-receptor, ATPM also acted as a mu-antagonist, as measured by its inhibition of morphine-induced antinociception. It is more important that ATPM had a greater ratio of the ED(50) value of sedation to that of antinociception than (-)U50,488 (11.8 versus 3.7), indicative of a less sedative effect than (-)U50,488H. In addition, ATPM showed less potential to develop antinociceptive tolerance relative to (-)U50,488H and morphine. Moreover, it dose-dependently inhibited morphine-induced antinociceptive tolerance. Furthermore, it was found that chronic treatment of rats for 8 consecutive days with ATPM (0.5 mg/kg s.c.) produced sustained decreases in heroin self-administration. (-)U50,488H (2 mg/kg s.c.) also produced similar inhibitory effect. Taken together, our findings demonstrated that ATPM, a novel mixed kappa-agonist and mu-agonist/-antagonist, could inhibit morphine-induced antinociceptive tolerance, with less potential to develop tolerance and reduce heroin self-administration with less sedative effect. kappa-Agonists with some mu-activity appear to offer some advantages over selective kappa-agonists for the treatment of heroin abuse.

PPAR agonists reduce steatosis in oleic acid-overloaded HepaRG cells

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

Rogue, Alexandra; Université de Rennes 1, Faculté des Sciences Pharmaceutiques et Biologiques, 35043 Rennes Cedex; Biologie Servier, Gidy

2014-04-01

Although non-alcoholic fatty liver disease (NAFLD) is currently the most common form of chronic liver disease there is no pharmacological agent approved for its treatment. Since peroxisome proliferator-activated receptors (PPARs) are closely associated with hepatic lipid metabolism, they seem to play important roles in NAFLD. However, the effects of PPAR agonists on steatosis that is a common pathology associated with NAFLD, remain largely controversial. In this study, the effects of various PPAR agonists, i.e. fenofibrate, bezafibrate, troglitazone, rosiglitazone, muraglitazar and tesaglitazar on oleic acid-induced steatotic HepaRG cells were investigated after a single 24-hour or 2-week repeat treatment. Lipid vesicles stainedmore » by Oil-Red O and triglycerides accumulation caused by oleic acid overload, were decreased, by up to 50%, while fatty acid oxidation was induced after 2-week co-treatment with PPAR agonists. The greatest effects on reduction of steatosis were obtained with the dual PPARα/γ agonist muraglitazar. Such improvement of steatosis was associated with up-regulation of genes related to fatty acid oxidation activity and down-regulation of many genes involved in lipogenesis. Moreover, modulation of expression of some nuclear receptor genes, such as FXR, LXRα and CAR, which are potent actors in the control of lipogenesis, was observed and might explain repression of de novo lipogenesis. Conclusion: Altogether, our in vitro data on steatotic HepaRG cells treated with PPAR agonists correlated well with clinical investigations, bringing a proof of concept that drug-induced reversal of steatosis in human can be evaluated in in vitro before conducting long-term and costly in vivo studies in animals and patients. - Highlights: • There is no pharmacological agent approved for the treatment of NAFLD. • This study demonstrates that PPAR agonists can reduce fatty acid-induced steatosis. • Some nuclear receptors appear to be potent actors in the

Agemone mexicana flavanones; apposite inverse agonists of the β2-adrenergic receptor in asthma treatment.

PubMed

Eniafe, Gabriel O; Metibemu, Damilohun S; Omotuyi, Olaposi I; Ogunleye, Adewale J; Inyang, Olumide K; Adelakun, Niyi S; Adeniran, Yakubu O; Adewumi, Bamidele; Enejoh, Ojochenemi A; Osunmuyiwa, Joseph O; Shodehinde, Sidiqat A; Oyeneyin, Oluwatoba E

2018-01-01

Asthma is an inflammatory disease of the airway that poses a major threat to human health. With increase industrialization in the developed and developing countries, the incidence of asthma is on the rise. The β2-adrenergic receptor is an important target in designing anti-asthmatic drugs. The synthetic agonists of the β2-adrenergic receptor used over the years proved effective, but with indispensable side effects, thereby limiting their therapeutic use on a long-term scale. Inverse agonists of this receptor, although initially contraindicated, had been reported to have long-term beneficial effects. Phytochemicals from Agemone mexicana were screened against the human β2-adrenergic receptor in the agonist, inverse agonist, covalent agonist, and the antagonist conformations. Molecular docking of the phyto-constituents showed that the plant constituents bind better to the inverse agonist bound conformation of the protein, and revealed two flavanones; eriodictyol and hesperitin, with lower free energy (ΔG) values and higher affinities to the inverse agonist bound receptor than the co-crystallized ligand. Eriodictyol and hesperitin bind with the glide score of -10.684 and - 9.958 kcal/mol respectively, while the standard compound ICI-118551, binds with glide score of -9.503 kcal/mol. Further interaction profiling at the protein orthosteric site and ADME/Tox screening confirmed the drug-like properties of these compounds.

The APO*E3-Leiden mouse as an animal model for basal laminar deposit

PubMed Central

Kliffen, M.; Lutgens, E.; Daemen, M.; de Muinck, E. D; Mooy, C.; de Jong, P. T V M

2000-01-01

AIM—To investigate the APO*E3-Leiden mouse as an animal model for age related maculopathy (ARM) related extracellular deposits.
METHODS—Eyes were obtained from APO*E3-Leiden transgenic mice on a high fat/cholesterol (HFC) diet (n=12) or on a normal mouse chow (n=6), for 9 months. As controls, eyes were collected from APO-E knockout mice on the same diets. From each mouse one eye was processed for microscopic evaluation and immunohistochemistry with a polyclonal antibody directed against human apo-E. Electron microscopy was also performed.
RESULTS—All 12 eyes of the APO*E3-Leiden mice on an HFC diet contained basal laminar deposit (BLD; class 1 to class 3), whereas two of six APO*E3-Leiden mice on normal chow showed BLD class 1. The ultrastructural aspects of this BLD were comparable with those seen in early BLD in humans, and BLD showed immunoreaction with anti-human-apo-E antibodies. No BLD was found in any of the control mice. Drusen were not detected in any of the mice.
CONCLUSION—These results indicate that APO*E3-Leiden mice can be used as animal model for the pathogenesis of BLD, and that a HFC diet enhances the accumulation of this deposit. Furthermore, this study supports the previously suggested involvement of dysfunctional apo-E in the accumulation of extracellular deposits in ARM.

 PMID:11090485

Discovery of Peripheral κ-Opioid Receptor Agonists as Novel Analgesics.

PubMed

Suzuki, Shinya; Sugawara, Yuji; Inada, Hideaki; Tsuji, Riichiro; Inoue, Atsushi; Tanimura, Ryuji; Shimozono, Rieko; Konno, Mitsuhiro; Ohyama, Tomofumi; Higashi, Eriko; Sakai, Chizuka; Kawai, Koji

2017-01-01

κ-Opioid receptor agonists with high selectivity over the μ-opioid receptor and peripheral selectivity are attractive targets in the development of drugs for pain. We have previously attempted to create novel analgesics with peripheral selective κ-opioid receptor agonist on the basis of TRK-820. In this study, we elucidated the biological properties of 17-hydroxy-cyclopropylmethyl and 10α-hydroxy derivatives. These compounds were found to have better κ-opioid receptor selectivity and peripheral selectivity than TRK-820.

Choline as an agonist: determination of its agonistic potency on cholinergic receptors.

PubMed

Ulus, I H; Millington, W R; Buyukuysal, R L; Kiran, B K

1988-07-15

These experiments examined the potency of choline as a cholinergic agonist at both muscarinic and nicotinic receptors in rat brain and peripheral tissues. Choline stimulated the contraction of isolated smooth muscle preparations of the stomach fundus, urinary bladder and trachea and reduced the frequency of spontaneous contractions of the right atrium at high micromolar and low millimolar concentrations. The potency of choline to elicit a biological response varied markedly among these tissues; EC50 values ranged between 0.41 mM in the fundus to 14.45 mM in the atrium. Choline also displaced [3H]quinuclidinyl benzilate binding in a concentration-dependent manner although, again, its potency varied among different brain regions (Ki = 1.2 to 3.5 mM) and peripheral tissues (Ki = 0.28 to 3.00 mM). Choline exhibited a comparable affinity for nicotinic receptors. It stimulated catecholamine release from the vascularly perfused adrenal gland (EC50 = 1.3 mM) and displaced L-[3H]nicotine binding to membrane preparations of brain and peripheral tissues (Ki = 0.38 to 1.17 mM). However, the concentration of choline required to bind to cholinergic receptors in most tissues was considerably higher than serum levels either in controls (8-13 microM) or following the administration of choline chloride (200 microM). These results clearly demonstrate that choline is a weak cholinergic agonist. Its potency is too low to account for the central nervous system effects produced by choline administration, although the direct activation of cholinergic receptors in several peripheral tissues may explain some of its side effects.

Metabotropic glutamate receptor agonists potentiate a slow afterdepolarization in CNS neurons

NASA Technical Reports Server (NTRS)

Zheng, F.; Gallagher, J. P.

1992-01-01

We have previously reported that, in the rat dorsolateral septal nucleus (DLSN), metabotropic glutamate receptor (met-GluR) agonists evoked a slow depolarization accompanied by an increase in membrane conductance and burst firing. We have speculated that the burst firing elicited by met-GluR agonists may be due to activation or enhancement of a non-specific cation current, which exists in some DLSN neurons. Now we report that a slow afterdepolarization (sADP) mediated by a non-specific cation current was potentiated by both 1S,3R-ACPD and quisqualate. In addition, met-GluR agonists unmask a sADP in DLSN neurons which did not show a sADP under control conditions. Our data suggest that a non-specific cation current can be potentiated by activation of the met-GluR.

Short-term treatment with a 2-carba analog of cyclic phosphatidic acid induces lowering of plasma cholesterol levels in ApoE-deficient mice.

PubMed

Tsukahara, Tamotsu; Haniu, Hisao; Matsuda, Yoshikazu; Murakmi-Murofushi, Kimiko

2016-04-22

Plasma cholesterol levels are associated with an increased risk of developing atherosclerosis. An elevated low-density lipoprotein cholesterol (LDL-C) level is a hallmark of hypercholesterolemia in metabolic syndrome. Our previous study suggested that when acetylated LDL (AC-LDL) was co-applied with a PPARγ agonist, rosiglitazone (ROSI), many oil red O-positive macrophages could be observed. However, addition of cyclic phosphatidic acid (cPA) to ROSI-stimulated macrophages completely abolished oil red O-stained cells, indicating that cPA inhibits PPARγ-regulated AC-LDL uptake. This study aimed to determine whether metabolically stabilized cPA, in the form of a carba-derivative of cPA (2ccPA), could reduce plasma cholesterol levels and affect the expression of genes related to atherosclerosis in apolipoprotein E-knockout (apoE(-/-)) mice. 2ccPA reduced LDL-C levels in these mice (n = 3) from 460 to 330 mg/ml, from 420 to 350 mg/ml, and 420 to 281 mg/ml under a western-type diet. 2ccPA also reduced expression of lipid metabolism-related genes, cytokines, and chemokines in ApoE-deficient mice on a high-fat diet. Taken together, these results suggest that 2ccPA governs anti-atherogenic activities in the carotid arteries of apoE-deficient mice. Copyright © 2016 Elsevier Inc. All rights reserved.

SIRT1 reduces endothelial activation without affecting vascular function in ApoE-/- mice

PubMed Central

Stein, Sokrates; Schäfer, Nicola; Breitenstein, Alexander; Besler, Christian; Winnik, Stephan; Lohmann, Christine; Heinrich, Kathrin; Brokopp, Chad E.; Handschin, Christoph; Landmesser, Ulf; Tanner, Felix C.; Lüscher, Thomas F.; Matter, Christian M.

2010-01-01

Excessive production of reactive oxygen species (ROS) contributes to progression of atherosclerosis, at least in part by causing endothelial dysfunction and inflammatory activation. The class III histone deacetylase SIRT1 has been implicated in extension of lifespan. In the vasculature,SIRT1 gain-of-function using SIRT1 overexpression or activation has been shown to improve endothelial function in mice and rats via stimulation of endothelial nitric oxide (NO) synthase (eNOS). However, the effects of SIRT1 loss-of-function on the endothelium in atherosclerosis remain to be characterized. Thus, we have investigated the endothelial effects of decreased endogenous SIRT1 in hypercholesterolemic ApoE-/- mice. We observed no difference in endothelial relaxation and eNOS (Ser1177) phosphorylation between 20-week old male atherosclerotic ApoE-/- SIRT1+/- and ApoE-/- SIRT1+/+ mice. However, SIRT1 prevented endothelial superoxide production, inhibited NF-κB signaling, and diminished expression of adhesion molecules. Treatment of young hypercholesterolemic ApoE-/- SIRT1+/- mice with lipopolysaccharide to boost NF-κB signaling led to a more pronounced endothelial expression of ICAM-1 and VCAM-1 as compared to ApoE-/- SIRT1+/+ mice. In conclusion, endogenous SIRT1 diminishes endothelial activation in ApoE-/- mice, but does not affect endothelium-dependent vasodilatation. PMID:20606253

The potency of different serotonergic agonists in counteracting opioid evoked cardiorespiratory disturbances

PubMed Central

Dutschmann, M.; Waki, H.; Manzke, T.; Simms, A. E.; Pickering, A. E.; Richter, D. W.; Paton, J. F. R.

2009-01-01

Serotonin receptor (5-HTR) agonists that target 5-HT4(a)R and 5-HT1AR can reverse μ-opioid receptor (μ-OR)-evoked respiratory depression. Here, we have tested whether such rescuing by serotonin agonists also applies to the cardiovascular system. In working heart–brainstem preparations in situ, we have recorded phrenic nerve activity, thoracic sympathetic chain activity (SCA), vascular resistance and heart rate (HR) and in conscious rats, diaphragmatic electromyogram, arterial blood pressure (BP) and HR via radio-telemetry. In addition, the distribution of 5-HT4(a)R and 5-HT1AR in ponto-medullary cardiorespiratory networks was identified using histochemistry. Systemic administration of the μ-OR agonist fentanyl in situ decreased HR, vascular resistance, SCA and phrenic nerve activity. Subsequent application of the 5-HT1AR agonist 8-OH-DPAT further enhanced bradycardia, but partially compensated the decrease in vascular resistance, sympathetic activity and restored breathing. By contrast, the 5-HT4(a)R agonist RS67333 further decreased vascular resistance, HR and sympathetic activity, but partially rescued breathing. In conscious rats, administration of remifentanyl caused severe respiratory depression, a decrease in mean BP accompanied by pronounced bradyarrhythmia. 8-OH-DPAT restored breathing and prevented the bradyarrhythmia; however, BP and HR remained below baseline. In contrast, RS67333 further suppressed cardiovascular functions in vivo and only partially recovered breathing in some cases. The better recovery of μ-OR cardiorespiratory disturbance by 5-HT1AR than 5-HT4(a)R is supported by the finding that 5-HT1AR was more densely expressed in key brainstem nuclei for cardiorespiratory control compared with 5-HT4(a)R. We conclude that during treatment of severe pain, 5-HT1AR agonists may provide a useful tool to counteract opioid-mediated cardiorespiratory disturbances. PMID:19651661

ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy.

PubMed

Shi, Yang; Yamada, Kaoru; Liddelow, Shane Antony; Smith, Scott T; Zhao, Lingzhi; Luo, Wenjie; Tsai, Richard M; Spina, Salvatore; Grinberg, Lea T; Rojas, Julio C; Gallardo, Gilbert; Wang, Kairuo; Roh, Joseph; Robinson, Grace; Finn, Mary Beth; Jiang, Hong; Sullivan, Patrick M; Baufeld, Caroline; Wood, Michael W; Sutphen, Courtney; McCue, Lena; Xiong, Chengjie; Del-Aguila, Jorge L; Morris, John C; Cruchaga, Carlos; Fagan, Anne M; Miller, Bruce L; Boxer, Adam L; Seeley, William W; Butovsky, Oleg; Barres, Ben A; Paul, Steven M; Holtzman, David M

2017-09-28

APOE4 is the strongest genetic risk factor for late-onset Alzheimer disease. ApoE4 increases brain amyloid-β pathology relative to other ApoE isoforms. However, whether APOE independently influences tau pathology, the other major proteinopathy of Alzheimer disease and other tauopathies, or tau-mediated neurodegeneration, is not clear. By generating P301S tau transgenic mice on either a human ApoE knock-in (KI) or ApoE knockout (KO) background, here we show that P301S/E4 mice have significantly higher tau levels in the brain and a greater extent of somatodendritic tau redistribution by three months of age compared with P301S/E2, P301S/E3, and P301S/EKO mice. By nine months of age, P301S mice with different ApoE genotypes display distinct phosphorylated tau protein (p-tau) staining patterns. P301S/E4 mice develop markedly more brain atrophy and neuroinflammation than P301S/E2 and P301S/E3 mice, whereas P301S/EKO mice are largely protected from these changes. In vitro, E4-expressing microglia exhibit higher innate immune reactivity after lipopolysaccharide treatment. Co-culturing P301S tau-expressing neurons with E4-expressing mixed glia results in a significantly higher level of tumour-necrosis factor-α (TNF-α) secretion and markedly reduced neuronal viability compared with neuron/E2 and neuron/E3 co-cultures. Neurons co-cultured with EKO glia showed the greatest viability with the lowest level of secreted TNF-α. Treatment of P301S neurons with recombinant ApoE (E2, E3, E4) also leads to some neuronal damage and death compared with the absence of ApoE, with ApoE4 exacerbating the effect. In individuals with a sporadic primary tauopathy, the presence of an ε4 allele is associated with more severe regional neurodegeneration. In individuals who are positive for amyloid-β pathology with symptomatic Alzheimer disease who usually have tau pathology, ε4-carriers demonstrate greater rates of disease progression. Our results demonstrate that ApoE affects tau

Developing Preschool Teachers&apos; Knowledge of Students&apos; Number Conceptions

ERIC Educational Resources Information Center

Tsamir, Pessia; Tirosh, Dina; Levenson, Esther; Tabach, Michal; Barkai, Ruthi

2014-01-01

This article describes a study that investigates preschool teachers&apos; knowledge of their young students&apos; number conceptions and the teachers&apos; related self-efficacy beliefs. It also presents and illustrates elements of a professional development program designed explicitly to promote this knowledge among preschool teachers. Results…

Activation of muscle nicotinic acetylcholine receptor channels by nicotinic and muscarinic agonists

PubMed Central

Akk, Gustav; Auerbach, Anthony

1999-01-01

The dose-response parameters of recombinant mouse adult neuromuscular acetylcholine receptor channels (nAChR) activated by carbamylcholine, nicotine, muscarine and oxotremorine were measured. Rate constants for agonist association and dissociation, and channel opening and closing, were estimated from single-channel kinetic analysis.The dissociation equilibrium constants were (mM): ACh (0.16)carbamylcholine (5.1)>oxotremorine M (0.6)>nicotine (0.5)>muscarine (0.15).Rat neuronal α4β2 nAChR can be activated by all of the agonists. However, detailed kinetic analysis was impossible because the recordings lacked clusters representing the activity of a single receptor complex. Thus, the number of channels in the patch was unknown and the activation rate constants could not be determined.Considering both receptor affinity and agonist efficacy, muscarine and oxotremorine are significant agonists of muscle-type nAChR. The results are discussed in terms of structure-function relationships at the nAChR transmitter binding site. PMID:10602325

Preclinical evaluation of SMM-189, a cannabinoid receptor 2-specific inverse agonist

PubMed Central

Presley, Chaela; Abidi, Ammaar; Suryawanshi, Satyendra; Mustafa, Suni; Meibohm, Bernd; Moore, Bob M

2015-01-01

Cannabinoid receptor 2 agonists and inverse agonists are emerging as new therapeutic options for a spectrum of autoimmune-related disease. Of particular interest, is the ability of CB2 ligands to regulate microglia function in neurodegenerative diseases and traumatic brain injury. We have previously reported the receptor affinity of 3′,5′-dichloro-2,6-dihydroxy-biphenyl-4-yl)-phenyl-methanone (SMM-189) and the characterization of the beneficial effects of SMM-189 in the mouse model of mild traumatic brain injury. Herein, we report the further characterization of SMM-189 as a potent and selective CB2 inverse agonist, which acts as a noncompetitive inhibitor of CP 55,940. The ability of SMM-189 to regulate microglial activation, in terms of chemokine expression and cell morphology, has been determined. Finally, we have determined that SMM-189 possesses acceptable biopharmaceutical properties indicating that the triaryl class of CB2 inverse agonists are viable compounds for continued preclinical development for the treatment of neurodegenerative disorders and traumatic brain injury. PMID:26196013

Mapping of ApoE4 related white matter damage using diffusion MRI

NASA Astrophysics Data System (ADS)

Tsao, Sinchai; Gajawelli, Niharika; Hwang, Darryl H.; Kriger, Stephen; Law, Meng; Chui, Helena; Weiner, Michael; Lepore, Natasha

2014-04-01

ApoliopoproteinE Ɛ4 (ApoE-Ɛ4) polymorphism is the most well known genetic risk factor for developing Alzheimers Disease. The exact mechanism through which ApoE 4 increases AD risk is not fully known, but may be related to decreased clearance and increased oligomerization of Aβ. By making measurements of white matter integrity via diffusion MR and correlating the metrics in a voxel-based statistical analysis with ApoE-Ɛ4 genotype (whilst controlling for vascular risk factor, gender, cognitive status and age) we are able to identify changes in white matter associated with carrying an ApoE Ɛ4 allele. We found potentially significant regions (Puncorrected < 0:05) near the hippocampus and the posterior cingulum that were independent of voxels that correlated with age or clinical dementia rating (CDR) status suggesting that ApoE may affect cognitive decline via a pathway in dependent of normal aging and acute insults that can be measured by CDR and Framingham Coronary Risk Score (FCRS).

[Effect of Huanglian Jiedu Decoction on Monocyte Development in apoE Gene Knockout Mice].

PubMed

Chen, Bing; Kong, Ya-xian; Ll, Yu-mei; Xue, Xin; Zhang, Jian-ping; Zeng, Hui; Hu, Jing- qing; Ma, Ya-luan

2016-01-01

To observe monocyte (Mo) development in wild type C57BL/6 mice and apoE gene knockout (apoE(-/-)) mice, and to evaluate the immuno-regulatory effect of Huanglian Jiedu Decoction (HJD) on peripheral Mo development in apoE(-/-) mice. Four, 8, 12, and 16 weeks old female C57BL/6 mice were set up as control groups of different ages, while 4, 8, 12, and 16 weeks old female apoE(-/-) mice were set up as hyperlipidemia groups of different ages. Four-week old female C57BL/6 mice were recruited as a blank group. Four-week old female apoE(-/-) mice were randomly divided into the control group, the Western medicine group, and the Chinese medicine group by paired comparison, 5 in each group. Equivalent clinical dose was administered to mice according to body weight. Mice in the Western medicine group were administered with Atrovastatin at the daily dose of 10 mg/kg by gastrogavage, while those in the Chinese medicine group were administered with HJD at the daily dose of 5 g/kg by gastrogavage. Body weight was detected each week. After 4 weeks blood lipids levels (such as TG, TC, LDL-C, and HDL-C), and the proportions of Mo and Ly6c(hi) were detected. Compared with 4-week-old homogenic mice, the proportion of Mo decreased in 16-week-old C57BL/6 mice (P < 0.05). Levels of TC and TG, and the proportion of Ly6c(hi) subtype increased, but the proportion of Mo de- creased in 8-week-old apoE(-/-) mice (P <0. 05). Levels of TC, TG, and LDL-C increased in 12-week-old apoE(-/-) mice (P < 0.05). Levels of TC, TG, LDL-C, and HDL-C increased in 16-week-old apoE(-/-) mice (P < 0.05, P < 0.01). Compared with 8-week-old homogenic mice, the proportion of Mo decreased in 16-week-old C57BL/6 mice (P < 0.05); levels of TC and LDL-C increased in 12-week-old apoE(-/-) mice (P < 0.05); levels of TC and HDL-C increased in 16-week-old apoE(-/-) mice (P < 0.05, P < 0.01). Compared with C57BL/6 mice of the same age, TC and TG increased, HDL-C decreased (P < 0.01) in 4-and 8-week-old apoE(-/-) mice (P

Effect of beta-ADrenergic Agonist on Cyclic AMP Synthesis in Chicken Skeletal Muscle Cells in Culture

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Because it seems logical that these agonists exert their action on muscle through stimulation of cAMP synthesis, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax levels were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. In addition, the EC50 values for isoproterenol, cimaterol, clenbuterol, epinephrine, and albuterol were 360 nM, 630 nM, 900 nM, 2,470 nM, and 3,650 nM, respectively. Finally, dose response curves show that the concentrations of cimaterol and clenbuterol in culture media at concentrations known to cause significant muscle hypertrophy in animals had no detectable effect on stimulation of CAMP accumulation in chicken skeletal muscle cells.

An intrinsic agonist mechanism for activation of glucagon-like peptide-1 receptor by its extracellular domain

PubMed Central

Yin, Yanting; Zhou, X Edward; Hou, Li; Zhao, Li-Hua; Liu, Bo; Wang, Gaihong; Jiang, Yi; Melcher, Karsten; Xu, H Eric

2016-01-01

The glucagon-like peptide-1 receptor is a class B G protein coupled receptor (GPCR) that plays key roles in glucose metabolism and is a major therapeutic target for diabetes. The classic two-domain model for class B GPCR activation proposes that the apo-state receptor is auto-inhibited by its extracellular domain, which physically interacts with the transmembrane domain. The binding of the C-terminus of the peptide hormone to the extracellular domain allows the N-terminus of the hormone to insert into the transmembrane domain to induce receptor activation. In contrast to this model, here we demonstrate that glucagon-like peptide-1 receptor can be activated by N-terminally truncated glucagon-like peptide-1 or exendin-4 when fused to the receptor, raising the question regarding the role of N-terminal residues of peptide hormone in glucagon-like peptide-1 receptor activation. Mutations of cysteine 347 to lysine or arginine in intracellular loop 3 transform the receptor into a G protein-biased receptor and allow it to be activated by a nonspecific five-residue linker that is completely devoid of exendin-4 or glucagon-like peptide-1 sequence but still requires the presence of an intact extracellular domain. Moreover, the extracellular domain can activate the receptor in trans in the presence of an intact peptide hormone, and specific mutations in three extracellular loops abolished this extracellular domain trans-activation. Together, our data reveal a dominant role of the extracellular domain in glucagon-like peptide-1 receptor activation and support an intrinsic agonist model of the extracellular domain, in which peptide binding switches the receptor from the auto-inhibited state to the auto-activated state by releasing the intrinsic agonist activity of the extracellular domain. PMID:27917297

Receptor-selective, peptidase-resistant agonists at neurokinin NK-1 and NK-2 receptors: new tools for investigating neurokinin function.

PubMed

Hagan, R M; Ireland, S J; Jordan, C C; Beresford, I J; Deal, M J; Ward, P

1991-06-01

The pharmacological profiles of two novel neurokinin agonists have been investigated. delta Ava[L-Pro9,N-MeLeu10]SP(7-11) (GR73632) and [Lys3,Gly8-R-gamma-lactam-Leu9] NKA(3-10) (GR64349) are potent and selective agonists at NK-1 and NK-2 receptors respectively. In the guinea-pig isolated trachea preparation, contractions induced by these agonists were largely unaffected by inclusion of peptidase inhibitors in the bathing medium, indicating that these agonists are resistant to metabolism by peptidases. In the anaesthetised guinea-pig, both agonists were more potent bronchoconstrictor agents than either NKA or the SP analogue, SP methylester. In the anaesthetised rat, the NK-1 agonist, GR73632 was more potent than SP, NKA or NKB at causing the histamine-independent extravasation of plasma proteins into the skin after intradermal administration. The NK-2 agonist, GR64349 and the NK-3 agonist, senktide were without significant effect in this model. These agonists are useful tools for characterizing neurokinin receptor-mediated actions both in vitro and in vivo.

Ligand-based receptor tyrosine kinase partial agonists: New paradigm for cancer drug discovery?

PubMed

Riese, David J

2011-02-01

INTRODUCTION: Receptor tyrosine kinases (RTKs) are validated targets for oncology drug discovery and several RTK antagonists have been approved for the treatment of human malignancies. Nonetheless, the discovery and development of RTK antagonists has lagged behind the discovery and development of agents that target G-protein coupled receptors. In part, this is because it has been difficult to discover analogs of naturally-occurring RTK agonists that function as antagonists. AREAS COVERED: Here we describe ligands of ErbB receptors that function as partial agonists for these receptors, thereby enabling these ligands to antagonize the activity of full agonists for these receptors. We provide insights into the mechanisms by which these ligands function as antagonists. We discuss how information concerning these mechanisms can be translated into screens for novel small molecule- and antibody-based antagonists of ErbB receptors and how such antagonists hold great potential as targeted cancer chemotherapeutics. EXPERT OPINION: While there have been a number of important key findings into this field, the identification of the structural basis of ligand functional specificity is still of the greatest importance. While it is true that, with some notable exceptions, peptide hormones and growth factors have not proven to be good platforms for oncology drug discovery; addressing the fundamental issues of antagonistic partial agonists for receptor tyrosine kinases has the potential to steer oncology drug discovery in new directions. Mechanism based approaches are now emerging to enable the discovery of RTK partial agonists that may antagonize both agonist-dependent and -independent RTK signaling and may hold tremendous promise as targeted cancer chemotherapeutics.

The Therapeutic Potential of Nociceptin/Orphanin FQ Receptor Agonists as Analgesics without Abuse Liability

PubMed Central

2012-01-01

Although mu opioid (MOP) receptor agonists are the most commonly used analgesics for the treatment of moderate to severe pain in the clinic, the side effects of MOP agonists such as abuse liability limit their value as a medication. Research to identify novel analgesics without adverse effects is pivotal to advance the health care of humans. The nociceptin/orphanin FQ peptide (NOP) receptor, the fourth opioid receptor subtype, mediates distinctive actions in nonhuman primates which suggests the possibility that activity at this receptor may result in strong analgesia in the absence of virtually all of the side effects associated with MOP agonists. The present review highlights the recent progress of pharmacological studies of NOP-related ligands in primates. Selective NOP agonists, either peptidic or nonpeptidic, produce full analgesia in various assays in primates, when delivered systemically or intrathecally. Yet small molecule NOP agonists do not serve as reinforcers, indicating a lack of abuse liability. Given that NOP agonists have low abuse liability and that coactivation of NOP and MOP receptors produces synergistic antinociception, it is worth developing bifunctional NOP/MOP ligands. The outcomes of these studies and recent developments provide new perspectives to establish a translational bridge for understanding the biobehavioral functions of NOP receptors in primates and for facilitating the development of NOP-related ligands as a new generation of analgesics without abuse liability in humans. PMID:23421672

[Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

PubMed

Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

2014-09-01

Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

The ε3 and ε4 alleles of human APOE differentially affect tau phosphorylation in hyperinsulinemic and pioglitazone treated mice.

PubMed

To, Alvina W M; Ribe, Elena M; Chuang, Tsu Tshen; Schroeder, Joern E; Lovestone, Simon

2011-02-10

Impaired insulin signalling is increasingly thought to contribute to Alzheimer's disease (AD). The ε4 isoform of the APOE gene is the greatest genetic risk factor for sporadic, late onset AD, and is also associated with risk for type 2 diabetes mellitus (T2DM). Neuropathological studies reported the highest number of AD lesions in brain tissue of ε4 diabetic patients. However other studies assessing AD pathology amongst the diabetic population have produced conflicting reports and have failed to show an increase in AD-related pathology in diabetic brain. The thiazolidinediones (TZDs), peroxisome proliferator-activated receptor gamma agonists, are peripheral insulin sensitisers used to treat T2DM. The TZD, pioglitazone, improved memory and cognitive functions in mild to moderate AD patients. Since it is not yet clear how apoE isoforms influence the development of T2DM and its progression to AD, we investigated amyloid beta and tau pathology in APOE knockout mice, carrying human APOEε3 or ε4 transgenes after diet-induced insulin resistance with and without pioglitazone treatment. Male APOE knockout, APOEε3-transgenic and APOEε4-transgenic mice, together with background strain C57BL6 mice were kept on a high fat diet (HFD) or low fat diet (LFD) for 32 weeks, or were all fed HFD for 32 weeks and during the final 3 weeks animals were treated with pioglitazone or vehicle. All HFD animals developed hyperglycaemia with elevated plasma insulin. Tau phosphorylation was reduced at 3 epitopes (Ser396, Ser202/Thr205 and Thr231) in all HFD, compared to LFD, animals independent of APOE genotype. The introduction of pioglitazone to HFD animals led to a significant reduction in tau phosphorylation at the Ser202/Thr205 epitope in APOEε3 animals only. We found no changes in APP processing however the levels of soluble amyloid beta 40 was reduced in APOE knockout animals treated with pioglitazone.

Apomorphine

MedlinePlus

... needle unit. Wash your hands with soap and water. If you already have a medication cartridge in the injector pen, go to step 7 below. To insert a new medication cartridge into the injector pen, follow steps 3 through 6. Pull off the grey pen cap. Unscrew the cartridge holder from the ...

Effect of vibration frequency on agonist and antagonist arm muscle activity.

PubMed

Rodríguez Jiménez, Sergio; Benítez, Adolfo; García González, Miguel A; Moras Feliu, Gerard; Maffiuletti, Nicola A

2015-06-01

This study aimed to assess the effect of vibration frequency (f out) on the electromyographic (EMG) activity of the biceps brachii (BB) and triceps brachii (TB) muscles when acting as agonist and antagonist during static exercises with different loads. Fourteen healthy men were asked to hold a vibratory bar as steadily as possible for 10 s during lying row (pulling) and bench press (pushing) exercise at f out of 0 (non-vibration condition), 18, 31 and 42 Hz with loads of 20, 50, and 80 % of the maximum sustainable load (MSL). The root mean square of the EMG activity (EMGRMS) of the BB and TB muscles was expressed as a function of the maximal EMGRMS for respective muscles to characterize agonist activation and antagonist coactivation. We found that (1) agonist activation was greater during vibration (42 Hz) compared to non-vibration exercise for the TB but not for the BB muscle (p < 0.05); (2) antagonist activation was greater during vibration compared to non-vibration exercise for both BB (p < 0.01) and TB (p < 0.05) muscles; (3) the vibration-induced increase in antagonist coactivation was proportional to vibration f out in the range 18-42 Hz and (4) the vibration-induced increase in TB agonist activation and antagonist coactivation occurred at all loading conditions in the range 20-80 % MSL. The use of high vibration frequencies within the range of 18-42 Hz can maximize TB agonist activation and antagonist activation of both BB and TB muscles during upper limb vibration exercise.

Signal Use by Octopuses in Agonistic Interactions.

PubMed

Scheel, David; Godfrey-Smith, Peter; Lawrence, Matthew

2016-02-08

Cephalopods show behavioral parallels to birds and mammals despite considerable evolutionary distance [1, 2]. Many cephalopods produce complex body patterns and visual signals, documented especially in cuttlefish and squid, where they are used both in camouflage and a range of interspecific interactions [1, 3-5]. Octopuses, in contrast, are usually seen as solitary and asocial [6, 7]; their body patterns and color changes have primarily been interpreted as camouflage and anti-predator tactics [8-12], though the familiar view of the solitary octopus faces a growing list of exceptions. Here, we show by field observation that in a shallow-water octopus, Octopus tetricus, a range of visible displays are produced during agonistic interactions, and these displays correlate with the outcome of those interactions. Interactions in which dark body color by an approaching octopus was matched by similar color in the reacting octopus were more likely to escalate to grappling. Darkness in an approaching octopus met by paler color in the reacting octopus accompanied retreat of the paler octopus. Octopuses also displayed on high ground and stood with spread web and elevated mantle, often producing these behaviors in combinations. This study is the first to document the systematic use of signals during agonistic interactions among octopuses. We show prima facie conformity of our results to an influential model of agonistic signaling [13]. These results suggest that interactions have a greater influence on octopus evolution than has been recognized and show the importance of convergent evolution in behavioral traits. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gene-environment interaction of ApoE genotype and combat exposure on PTSD.

PubMed

Lyons, Michael J; Genderson, Margo; Grant, Michael D; Logue, Mark; Zink, Tyler; McKenzie, Ruth; Franz, Carol E; Panizzon, Matthew; Lohr, James B; Jerskey, Beth; Kremen, William S

2013-10-01

Factors determining who develops PTSD following trauma are not well understood. The €4 allele of the apolipoprotein E (apoE) gene is associated with dementia and unfavorable outcome following brain insult. PTSD is also associated with dementia. Given evidence that psychological trauma adversely affects the brain, we hypothesized that the apoE genotype moderates effects of psychological trauma on PTSD pathogenesis. To investigate the moderation of the relationship between PTSD symptoms and combat exposure, we used 172 participants with combat trauma sustained during the Vietnam War. PTSD symptoms were the dependent variable and number of combat experiences, apoE genotype, and the combat experiences × apoE genotype interaction were predictors. We also examined the outcome of a diagnosis of PTSD (n = 39) versus no PTSD diagnosis (n = 131). The combat × apoE genotype interaction was significant for both PTSD symptoms (P = .014) and PTSD diagnosis (P = .009). ApoE genotype moderates the relationship between combat exposure and PTSD symptoms. Although the pathophysiology of PTSD is not well understood, the €4 allele is related to reduced resilience of the brain to insult. Our results are consistent with the €4 allele influencing the effects of psychological trauma on the brain, thereby affecting the risk of PTSD. © 2013 Wiley Periodicals, Inc.

Characterization of 12 GnRH peptide agonists - a kinetic perspective.

PubMed

Nederpelt, Indira; Georgi, Victoria; Schiele, Felix; Nowak-Reppel, Katrin; Fernández-Montalván, Amaury E; IJzerman, Adriaan P; Heitman, Laura H

2016-01-01

Drug-target residence time is an important, yet often overlooked, parameter in drug discovery. Multiple studies have proposed an increased residence time to be beneficial for improved drug efficacy and/or longer duration of action. Currently, there are many drugs on the market targeting the gonadotropin-releasing hormone (GnRH) receptor for the treatment of hormone-dependent diseases. Surprisingly, the kinetic receptor-binding parameters of these analogues have not yet been reported. Therefore, this project focused on determining the receptor-binding kinetics of 12 GnRH peptide agonists, including many marketed drugs. A novel radioligand-binding competition association assay was developed and optimized for the human GnRH receptor with the use of a radiolabelled peptide agonist, [(125) I]-triptorelin. In addition to radioligand-binding studies, a homogeneous time-resolved FRET Tag-lite™ method was developed as an alternative assay for the same purpose. Two novel competition association assays were successfully developed and applied to determine the kinetic receptor-binding characteristics of 12 high-affinity GnRH peptide agonists. Results obtained from both methods were highly correlated. Interestingly, the binding kinetics of the peptide agonists were more divergent than their affinities with residence times ranging from 5.6 min (goserelin) to 125 min (deslorelin). Our research provides new insights by incorporating kinetic, next to equilibrium, binding parameters in current research and development that can potentially improve future drug discovery targeting the GnRH receptor. © 2015 The British Pharmacological Society.

Adenosine A2A receptor agonists with potent antiplatelet activity.

PubMed

Fuentes, Eduardo; Fuentes, Manuel; Caballero, Julio; Palomo, Iván; Hinz, Sonja; El-Tayeb, Ali; Müller, Christa E

2018-05-01

Selected adenosine A 2A receptor agonists (PSB-15826, PSB-12404, and PSB-16301) have been evaluated as new antiplatelet agents. In addition, radioligand-binding studies and receptor-docking experiments were performed in order to explain their differential biological effects on a molecular level. Among the tested adenosine derivatives, PSB-15826 was the most potent compound to inhibit platelet aggregation (EC 50 0.32 ± 0.05 µmol/L) and platelet P-selectin cell-surface localization (EC 50 0.062 ± 0.2 µmol/L), and to increase intraplatelets cAMP levels (EC 50 0.24 ± 0.01 µmol/L). The compound was more active than CGS21680 (EC 50 0.97±0.07 µmol/L) and equipotent to NECA (EC 50 0.31 ± 0.05 µmol/L) in platelet aggregation induced by ADP. In contrast to the results from cAMP assays, K i values determined in radioligand-binding studies were not predictive of the A 2A agonists' antiplatelet activity. Docking studies revealed the key molecular determinants of this new family of adenosine A 2A receptor agonists: differences in activities are related to π-stacking interactions between the ligands and the residue His264 in the extracellular loop of the adenosine A 2A receptor which may result in increased residence times. In conclusion, these results provide an improved understanding of the requirements of antiplatelet adenosine A 2A receptor agonists.

SAP deficiency mitigated atherosclerotic lesions in ApoE(-/-) mice.

PubMed

Zheng, Lingyun; Wu, Teng; Zeng, Cuiling; Li, Xiangli; Li, Xiaoqiang; Wen, Dingwen; Ji, Tianxing; Lan, Tian; Xing, Liying; Li, Jiangchao; He, Xiaodong; Wang, Lijing

2016-01-01

Serum amyloid P conpoent (SAP), a member of the pentraxin family, interact with pathogens and cell debris to promote their removal by macrophages and neutrophils and is co-localized with atherosclerotic plaques in patients. However, the exact mechanism of SAP in atherogenesis is still unclear. We investigated whether SAP influence macrophage recruitment and foam cell formation and ultimately affect atherosclerotic progression. we generated apoE(-/-); SAP(-/-) (DKO) mice and fed them western diet for 4 and 8 weeks to characterize atherosclerosis development. SAP deficiency effectively reduced plaque size both in the aorta (p = 0.0006 for 4 wks; p = 0.0001 for 8 wks) and the aortic root (p = 0.0061 for 4 wks; p = 0.0079 for 8wks) compared with apoE(-/-) mice. Meanwhile, SAP deficiency inhibited oxLDL-induced foam cell formation (p = 0.0004) compared with apoE(-/-) mice and SAP treatment increases oxLDL-induced foam cell formation (p = 0.002) in RAW cells. Besides, SAP deficiency reduced macrophages recruitment (p = 0.035) in vivo and in vitro (p = 0.026). Furthermore, SAP treatment enhanced CD36 (p = 0.007) and FcγRI (p = 0.031) expression induced by oxLDL through upregulating JNK and p38 MAPK phosphorylation whereas specific JNK1/2 inhibitor reduced CD36 (p = 0.0005) and FcγRI (P = 0.0007) expression in RAW cell. SAP deficiency also significantly decreased the expression of M1 and M2 macrophage markers and inflammatory cytokines in oxLDL-induced macrophages. SAP deficiency mitigated foam cell formation and atherosclerotic development in apoE(-/-) mice, due to reduction in macrophages recruitment, polarization and pro-inflammatory cytokines and inhibition the CD36/FcγR-dependent signaling pathway. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Measuring Beliefs in Centimeters: Private Knowledge Biases Preschoolers&apos; and Adults&apos; Representation of Others&apos; Beliefs

ERIC Educational Resources Information Center

Sommerville, Jessica A.; Bernstein, Daniel M.; Meltzoff, Andrew N.

2013-01-01

A novel task, using a continuous spatial layout, was created to investigate the degree to which (in centimeters) 3-year-old children&apos;s ("N" = 63), 5-year-old children&apos;s ("N" = 60), and adults&apos; ("N" = 60) own privileged knowledge of the location of an object biased their representation of a…

Rational design of orally-active, pyrrolidine-based progesterone receptor partial agonists

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

Thompson, Scott K.; Washburn, David G.; Frazee, James S.

2010-09-03

Using the X-ray crystal structure of an amide-based progesterone receptor (PR) partial agonist bound to the PR ligand binding domain, a novel PR partial agonist class containing a pyrrolidine ring was designed. Members of this class of N-alkylpyrrolidines demonstrate potent and highly selective partial agonism of the progesterone receptor, and one of these analogs was shown to be efficacious upon oral dosing in the OVX rat model of estrogen opposition.

Neuropeptide metabolism on intact, regional brain slices: effect of dopaminergic agents on substance P, cholecystokinin and Met-enkephalin degradation.

PubMed

Waters, S M; Konkoy, C S; Davis, T P

1995-08-01

Neuroleptic drugs have been shown to affect the level and messenger ribonucleic acid of specific neuropeptides. The effect of subchronically administered neuroleptics on neuropeptide metabolism, however, has not been systematically characterized. In the present study, the effect of neuroleptics and other dopaminergic compounds on substance P (SP), cholecystokinin and met-enkephalin degradation was determined on intact, regional, rat brain slices. After 7-day administration of haloperidol (1 mg/kg) or chlorpromazine (20 mg/kg), SP degradation was decreased in caudate-putamen and nucleus accumbens. After administration of the dopaminergic agonist apomorphine (5 mg/kg, b.i.d.), SP degradation was increased in the nucleus accumbens. The dopamine D2-receptor antagonist sulpiride (100 mg/kg, b.i.d.) produced no effect on SP degradation. Met-enkephalin degradation was decreased after haloperidol administration in both frontal cortex and caudate-putamen and unaffected by apomorphine administration. The metabolism of cholecystokinin was not affected by neuroleptic treatment. Studies performed with specific peptidase inhibitors suggested that neutral endopeptidase 24.11, metalloendopeptidase 24.15 and aminopeptidases degrade SP on caudate-putamen and nucleus accumbens slices. Therefore, alterations in these peptidases may be responsible for the change noted in SP degradation after dopaminergic compound administration. These metabolic changes noted after neuroleptic administration may therefore contribute to neuroleptic-induced alterations in regional peptide levels.

6'-Guanidinonaltrindole (6'-GNTI) is a G protein-biased κ-opioid receptor agonist that inhibits arrestin recruitment.

PubMed

Rives, Marie-Laure; Rossillo, Mary; Liu-Chen, Lee-Yuan; Javitch, Jonathan A

2012-08-03

κ-Opioid receptor (KOR) agonists do not activate the reward pathway stimulated by morphine-like μ-opioid receptor (MOR) agonists and thus have been considered to be promising nonaddictive analgesics. However, KOR agonists produce other adverse effects, including dysphoria, diuresis, and constipation. The therapeutic promise of KOR agonists has nonetheless recently been revived by studies showing that their dysphoric effects require arrestin recruitment, whereas their analgesic effects do not. Moreover, KOR agonist-induced antinociceptive tolerance observed in vivo has also been proposed to be correlated to the ability to induce arrestin-dependent phosphorylation, desensitization, and internalization of the receptor. The discovery of functionally selective drugs that are therapeutically effective without the adverse effects triggered by the arrestin pathway is thus an important goal. We have identified such an extreme G protein-biased KOR compound, 6'-guanidinonaltrindole (6'-GNTI), a potent partial agonist at the KOR receptor for the G protein activation pathway that does not recruit arrestin. Indeed, 6'-GNTI functions as an antagonist to block the arrestin recruitment and KOR internalization induced by other nonbiased agonists. As an extremely G protein-biased KOR agonist, 6'-GNTI represents a promising lead compound in the search for nonaddictive opioid analgesic as its signaling profile suggests that it will be without the dysphoria and other adverse effects promoted by arrestin recruitment and its downstream signaling.

Estradiol agonists inhibit human LoVo colorectal-cancer cell proliferation and migration through p53.

PubMed

Hsu, Hsi-Hsien; Kuo, Wei-Wen; Ju, Da-Tong; Yeh, Yu-Lan; Tu, Chuan-Chou; Tsai, Ying-Lan; Shen, Chia-Yao; Chang, Sheng-Huang; Chung, Li-Chin; Huang, Chih-Yang

2014-11-28

To investigate the effects of 17β-estradiol via estrogen receptors (ER) or direct administration of ER agonists on human colorectal cancer. LoVo cells were established from the Bioresource Collection and Research Center and cultured in phenol red-free DMEM (Sigma, United States). To investigate the effects of E2 and/or ER selective agonists on cellular proliferation, LoVo colorectal cells were treated with E2 or ER-selective agonists for 24 h and 48 h and subjected to the MTT (Sigma) assay to find the concentration. And investigate the effects of E2 and/or ER selective agonists on cell used western immunoblotting to find out the diversification of signaling pathways. In order to observe motility and migration the wound healing assay and a transwell chamber (Neuro Probe) plate were tased. For a quantitative measure, we counted the number of migrating cells to the wound area post-wounding for 24 h. We further examined the cellular migration-regulating factors urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA) and matrix metalloproteinase (MMP)-9 in human LoVo cells so gelatin zymography that we used and gelatinolytic activity was visualized by Coomassie blue staining. And these results are presented as means ± SE, and statistical comparisons were made using Student's t-test. The structure was first compared with E2 and ER agonists. We then treated the LoVo cells with E2 and ER agonists (10(-8) mol/L) for 24 h and 48 h and subsequently measured the cell viability using MTT assay. Our results showed that treatment with 17β-estradiol and/or ER agonists in human LoVo colorectal cancer cells activated p53 and then up-regulated p21 and p27 protein levels, subsequently inhibiting the downstream target gene, cyclin D1, which regulates cell proliferation. Taken together, our findings demonstrate the anti-tumorigenesis effects of 17β-estradiol and/or ER agonists and suggest that these compounds may prove to be a potential alternative

Find novel dual-agonist drugs for treating type 2 diabetes by means of cheminformatics.

PubMed

Liu, Lei; Ma, Ying; Wang, Run-Ling; Xu, Wei-Ren; Wang, Shu-Qing; Chou, Kuo-Chen

2013-01-01

The high prevalence of type 2 diabetes mellitus in the world as well as the increasing reports about the adverse side effects of the existing diabetes treatment drugs have made developing new and effective drugs against the disease a very high priority. In this study, we report ten novel compounds found by targeting peroxisome proliferator-activated receptors (PPARs) using virtual screening and core hopping approaches. PPARs have drawn increasing attention for developing novel drugs to treat diabetes due to their unique functions in regulating glucose, lipid, and cholesterol metabolism. The reported compounds are featured with dual functions, and hence belong to the category of dual agonists. Compared with the single PPAR agonists, the dual PPAR agonists, formed by combining the lipid benefit of PPARα agonists (such as fibrates) and the glycemic advantages of the PPARγ agonists (such as thiazolidinediones), are much more powerful in treating diabetes because they can enhance metabolic effects while minimizing the side effects. This was observed in the studies on molecular dynamics simulations, as well as on absorption, distribution, metabolism, and excretion, that these novel dual agonists not only possessed the same function as ragaglitazar (an investigational drug developed by Novo Nordisk for treating type 2 diabetes) did in activating PPARα and PPARγ, but they also had more favorable conformation for binding to the two receptors. Moreover, the residues involved in forming the binding pockets of PPARα and PPARγ among the top ten compounds are explicitly presented, and this will be very useful for the in-depth conduction of mutagenesis experiments. It is anticipated that the ten compounds may become potential drug candidates, or at the very least, the findings reported here may stimulate new strategies or provide useful insights for designing new and more powerful dual-agonist drugs for treating type 2 diabetes.

Comparative Gene Expression Profiles Induced by PPARγ and PPARα/γ Agonists in Human Hepatocytes

PubMed Central

Rogue, Alexandra; Lambert, Carine; Jossé, Rozenn; Antherieu, Sebastien; Spire, Catherine; Claude, Nancy; Guillouzo, André

2011-01-01

Background Several glitazones (PPARγ agonists) and glitazars (dual PPARα/γ agonists) have been developed to treat hyperglycemia and, simultaneously, hyperglycemia and dyslipidemia, respectively. However, most have caused idiosyncratic hepatic or extrahepatic toxicities through mechanisms that remain largely unknown. Since the liver plays a key role in lipid metabolism, we analyzed changes in gene expression profiles induced by these two types of PPAR agonists in human hepatocytes. Methodology/Principal Findings Primary human hepatocytes and the well-differentiated human hepatoma HepaRG cells were exposed to different concentrations of two PPARγ (troglitazone and rosiglitazone) and two PPARα/γ (muraglitazar and tesaglitazar) agonists for 24 h and their transcriptomes were analyzed using human pangenomic Agilent microarrays. Principal Component Analysis, hierarchical clustering and Ingenuity Pathway Analysis® revealed large inter-individual variability in the response of the human hepatocyte populations to the different compounds. Many genes involved in lipid, carbohydrate, xenobiotic and cholesterol metabolism, as well as inflammation and immunity, were regulated by both PPARγ and PPARα/γ agonists in at least a number of human hepatocyte populations and/or HepaRG cells. Only a few genes were selectively deregulated by glitazars when compared to glitazones, indicating that PPARγ and PPARα/γ agonists share most of their target genes. Moreover, some target genes thought to be regulated only in mouse or to be expressed in Kupffer cells were also found to be responsive in human hepatocytes and HepaRG cells. Conclusions/Significance This first comprehensive analysis of gene regulation by PPARγ and PPARα/γ agonists favor the conclusion that glitazones and glitazars share most of their target genes and induce large differential changes in gene profiles in human hepatocytes depending on hepatocyte donor, the compound class and/or individual compound, thereby

Cigarette smoke exposure inhibits contact hypersensitivity via the generation of platelet activating factor agonists

PubMed Central

Sahu, Ravi P.; Petrache, Irina; Van Demark, Mary J; Rashid, Badri M.; Ocana, Jesus A.; Tang, Yuxuan; Yi, Qiaofang; Turner, Matthew J.; Konger, Raymond L.; Travers, Jeffrey B.

2013-01-01

Previous studies have established that pro-oxidative stressors suppress host immunity due to their ability to generate oxidized lipids with PAF-receptor (PAF-R) agonist activity. Although exposure to the pro-oxidative stressor cigarette smoke (CS) is known to exert immunomodulatory effects, little is known regarding the role of platelet-activating factor (PAF) in these events. The current studies sought to determine the role of PAF-R signaling in CS-mediated immunomodulatory effects. We demonstrate that CS exposure induces the generation of a transient PAF-R agonistic activity in the blood of mice. CS exposure inhibits contact hypersensitivity in a PAF-R-dependent manner as PAF-R-deficient mice were resistant to these effects. Blocking PAF-R agonist production either by systemic antioxidants or treatment with serum PAF-acetyl hydrolase enzyme blocked both the CS-mediated generation of PAF-R-agonists and PAF-R dependent inhibition of CHS reactions, indicating a role for oxidized glycerophosphocholines with PAF-R agonistic activity in this process. In addition, cyclooxygenase-2 (COX-2) inhibition did not block PAF-R agonist production but prevented CS-induced inhibition of CHS. This suggests that COX-2 acts downstream of the PAF-R in mediating CS-induced systemic immunosuppression. Moreover, CS-exposure induced a significant increase in the expression of the regulatory T cell reporter gene in FoxP3EGFP mice but not in FoxP3EGFP mice on a PAF-R-deficient background. Finally, Treg depletion via anti-CD25 antibodies blocked CS-mediated inhibition of CHS, indicating the potential involvement of Tregs in CS-mediated systemic immunosuppression. These studies provide the first evidence that the pro-oxidative stressor CS can modulate cutaneous immunity via the generation of PAF-R agonists produced through lipid oxidation. PMID:23355733

Structure of an agonist-bound ionotropic glutamate receptor.

PubMed

Yelshanskaya, Maria V; Li, Minfen; Sobolevsky, Alexander I

2014-08-29

Ionotropic glutamate receptors (iGluRs) mediate most excitatory neurotransmission in the central nervous system and function by opening their ion channel in response to binding of agonist glutamate. Here, we report a structure of a homotetrameric rat GluA2 receptor in complex with partial agonist (S)-5-nitrowillardiine. Comparison of this structure with the closed-state structure in complex with competitive antagonist ZK 200775 suggests conformational changes that occur during iGluR gating. Guided by the structures, we engineered disulfide cross-links to probe domain interactions that are important for iGluR gating events. The combination of structural information, kinetic modeling, and biochemical and electrophysiological experiments provides insight into the mechanism of iGluR gating. Copyright © 2014, American Association for the Advancement of Science.

AMPK and PPARδ agonists are exercise mimetics

PubMed Central

Narkar, Vihang A.; Downes, Michael; Yu, Ruth T.; Embler, Emi; Wang, Yong-Xu; Banayo, Ester; Mihaylova, Maria M.; Nelson, Michael C.; Zou, Yuhua; Juguilon, Henry; Kang, Heonjoong; Shaw, Reuben; Evans, Ronald M.

2008-01-01

SUMMARY The benefits of endurance exercise on general health make it desirable to identify orally active agents that would mimic or potentiate the effects of exercise to treat metabolic diseases. Although certain natural compounds, such as reseveratrol, have endurance-enhancing activities, their exact metabolic targets remain elusive. We therefore tested the effect of pathway-specific drugs on endurance capacities of mice in a treadmill running test. We found that PPARβ/δ agonist and exercise training synergistically increase oxidative myofibers and running endurance in adult mice. Because training activates AMPK and PGC1α, we then tested whether the orally active AMPK agonist AICAR might be sufficient to overcome the exercise requirement. Unexpectedly, even in sedentary mice, 4 weeks of AICAR treatment alone induced metabolic genes and enhanced running endurance by 44%. These results demonstrate that AMPK-PPARδ pathway can be targeted by orally active drugs to enhance training adaptation or even to increase endurance without exercise. PMID:18674809

Antagonism of methoxyflurane-induced anesthesia in rats by benzodiazepine inverse agonists.

PubMed

Miller, D W; Yourick, D L; Tessel, R E

1989-11-28

Injection of the partial benzodiazepine inverse agonist Ro15-4513 (1-32 mg/kg i.p.) or nonconvulsant i.v. doses of the full benzodiazepine inverse agonist beta-CCE immediately following cessation of exposure of rats to an anesthetic concentration of methoxyflurane significantly antagonized the duration of methoxyflurane anesthesia as measured by recovery of the righting reflex and/or pain sensitivity. This antagonism was inhibited by the benzodiazepine antagonist Ro15-1788 at doses which alone did not alter the duration of methoxyflurane anesthesia. In addition, high-dose Ro15-4513 pretreatment (32 mg/kg) antagonized the induction and duration of methoxyflurane anesthesia but was unable to prevent methoxyflurane anesthesia or affect the induction or duration of anesthesia induced by the dissociative anesthetic ketamine (100 mg/kg). These findings indicate that methoxyflurane anesthesia can be selectively antagonized by the inverse agonistic action of Ro15-4513 and beta-CCE.

Alpha-2 adrenergic agonists for the prevention of cardiac complications among adults undergoing surgery.

PubMed

Duncan, Dallas; Sankar, Ashwin; Beattie, W Scott; Wijeysundera, Duminda N

2018-03-06

The surgical stress response plays an important role on the pathogenesis of perioperative cardiac complications. Alpha-2 adrenergic agonists attenuate this response and may help prevent postoperative cardiac complications. To determine the efficacy and safety of α-2 adrenergic agonists for reducing mortality and cardiac complications in adults undergoing cardiac surgery and non-cardiac surgery. We searched CENTRAL (2017, Issue 4), MEDLINE (1950 to April Week 4, 2017), Embase (1980 to May 2017), the Science Citation Index, clinical trial registries, and reference lists of included articles. We included randomized controlled trials that compared α-2 adrenergic agonists (i.e. clonidine, dexmedetomidine or mivazerol) against placebo or non-α-2 adrenergic agonists. Included trials had to evaluate the efficacy and safety of α-2 adrenergic agonists for preventing perioperative mortality or cardiac complications (or both), or measure one or more relevant outcomes (i.e. death, myocardial infarction, heart failure, acute stroke, supraventricular tachyarrhythmia and myocardial ischaemia). Two authors independently assessed trial quality, extracted data and independently performed computer entry of abstracted data. We contacted study authors for additional information. Adverse event data were gathered from the trials. We evaluated included studies using the Cochrane 'Risk of bias' tool, and the quality of the evidence underlying pooled treatment effects using GRADE methodology. Given the clinical heterogeneity between cardiac and non-cardiac surgery, we analysed these subgroups separately. We expressed treatment effects as pooled risk ratios (RR) with 95% confidence intervals (CI). We included 47 trials with 17,039 participants. Of these studies, 24 trials only included participants undergoing cardiac surgery, 23 only included participants undergoing non-cardiac surgery and eight only included participants undergoing vascular surgery. The α-2 adrenergic agonist studied

Virtual identification of novel PPARα/γ dual agonists by scaffold hopping of saroglitazar.

PubMed

Jia, Wen-Qing; Jing, Zhi; Liu, Xin; Feng, Xiao-Yan; Liu, Ya-Ya; Wang, Shu-Qing; Xu, Wei-Ren; Liu, Jian-Wen; Cheng, Xian-Chao

2017-10-28

The thiazolidinedione class PPARγ agonists as antidiabetic agents are restricted in clinical use because of the side effects such as edema, weight gain, and heart failure. The single and selective agonism of PPARγ is the main cause of side effects. The multi-target cooperative PPARα/γ dual agonist development is a hot topic in the antidiabetic medicinal chemistry field. Saroglitazar is the first approved PPARα/γ dual agonist, available in India for the treatment of diabetic dyslipidemia. It got rid of these side effects. With the aim of finding more protent PPARα/γ dual agonists, the scaffold hopping was used to replace α-o phenylpropionic acid skeleton of saroglitazar with L-tyrosine skeleton. Then, the structural modification was carried out designing 72 compounds. Considering the importance of chirality, opposite configuration of 72 compounds was also studied. 12 compounds with better -cdocker energy were screened by molecular docking. Subsequently, the pharmacokinetic properties and toxicity evaluated by ADMET prediction, 11 of them showed better properties. Comp#L-17-1 and comp#L-3-1 were regarded as representatives to study the binding stability by molecular dynamics (MD) simulations. The MD simulation results of comp#L-17-1-PPARs (α, γ) and comp#L-3-1-PPARs (α, γ) provided structure reference for the research and development of novel PPARα/γ dual agonists.

Combined ovulation triggering with GnRH agonist and hCG in IVF patients.

PubMed

Kasum, Miro; Kurdija, Kristijan; Orešković, Slavko; Čehić, Ermin; Pavičić-Baldani, Dinka; Škrgatić, Lana

2016-11-01

The aim of the review is to analyse the combination of a gonadotrophin releasing hormone (GnRH) agonist with a human chorionic gonadotrophin (hCG) trigger, for final oocyte maturation in in vitro fertilisation (IVF) cycles. The concept being a ''dual trigger'' combines a single dose of the GnRH agonist with a reduced or standard dosage of hCG at the time of triggering. The use of a GnRH agonist with a reduced dose of hCG in high responders demonstrated luteal phase support with improved pregnancy rates, similar to those after conventional hCG and a low risk of ovarian hyperstimulation syndrome (OHSS). The administration of a GnRH agonist and a standard hCG in normal responders, demonstrated significantly improved live-birth rates and a higher number of embryos of excellent quality, or cryopreserved embryos. The concept of the ''double trigger" represents a combination of a GnRH agonist and a standard hCG, when used 40 and 34 h prior to ovum pick-up, respectively. The use of the ''double trigger" has been successfully offered in the treatment of empty follicle syndrome and in patients with a history of immature oocytes retrieved or with low/poor oocytes yield. Further prospective studies are required to confirm the aforementioned observations prior to clinical implementation.

Antineoplastic Effects of PPARγ Agonists, with a Special Focus on Thyroid Cancer.

PubMed

Ferrari, Silvia Martina; Materazzi, Gabriele; Baldini, Enke; Ulisse, Salvatore; Miccoli, Paolo; Antonelli, Alessandro; Fallahi, Poupak

2016-01-01

Peroxisome Proliferator-Activated Receptor-γ (PPARγ) is a ligand-activated nuclear hormone receptor that functions as transcription factor and plays an important role in lipid metabolism and insulin sensitization. Recent studies have shown that PPARγ is overexpressed in many tumor types, including cancers of breast, lung, pancreas, colon, glioblastoma, prostate and thyroid differentiated/anaplastic cancers. These data suggest a role of PPARγ in tumor development and/or progression. PPARγ is emerging as a growth-limiting and differentiation-promoting factor, and it exerts a tumor suppressor role. Moreover, naturally-occurring and synthetic PPARγ agonists promote growth inhibition and apoptosis. Thiazolidinediones (TZDs) are synthetic agonists of PPARγ that were developed to treat type II diabetes. These compounds also display anticancer effects which appear mainly to be independent of their PPARγ agonist activity. Various preclinical and clinical studies strongly suggest a role for TZDs both alone and in combination with existing chemotherapeutic agents, for the treatment of cancer. Differentiation therapy involves the use of agents with the ability to induce differentiation in cells that have lost this ability, i.e. cancer cells, targeting pathways capable of re-activating blocked terminal differentiation programs. PPARγ agonists have been shown to induce differentiation in solid tumors such as thyroid differentiated/ anaplastic cancers and sarcomas. However, emerging data suggest that chronic use of TZDs is associated with increased risk of adverse cardiovascular events. The exploration of newer PPARγ agonists can help in unveiling the underlying mechanisms of these drugs, providing new molecules that are able to treat cancer, without increasing the cardiovascular risk of neoplastic patients.

PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR) AGONISTS AS PROMISING NEW MEDICATIONS FOR DRUG ADDICTION: PRECLINICAL EVIDENCE

PubMed Central

Foll, Bernard Le; Ciano, Patricia Di; Panlilio, Leigh V.; Goldberg, Steven R.; Ciccocioppo, Roberto

2013-01-01

This review examines the growing literature on the role of peroxisome proliferator-activated receptors (PPARs) in addiction. There are two subtypes of PPAR receptors that have been studied in addiction: PPAR-α and PPAR-γ. The role of each PPAR subtype in common models of addictive behavior, mainly pre-clinical models, is summarized. In particular, studies are reviewed that investigated the effects of PPAR-α agonists on relapse, sensitization, conditioned place preference, withdrawal and drug intake, and effects of PPAR-γ agonists on relapse, withdrawal and drug intake. Finally, studies that investigated the effects of PPAR agonists on neural pathways of addiction are reviewed. Taken together this preclinical data indicates that PPAR agonists are promising new medications for drug addiction treatment. PMID:23614675

Ethanol induces rotational behavior in 6-hydroxydopamine lesioned mice

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

Silverman, P.B.

1987-03-09

Mice with unilateal striatal lesions created by 6-hydroxydopamine (6HDA) injection were screened for rotational (circling) behavior in response to injection of amphetamine and apomorphine. Those that rotated ipsilaterally in response to amphetamine and contralaterally in response to apomorphine were subsequently challenged with 1 to 3 g/kg (i.p.) ethanol. Surprisingly, ethanol induced dose related contralateral (apomorphine-like) rotation which, despite gross intoxication, was quite marked in most animals. No significant correlation was found between the number of turns made following ethanol and made after apomorphine or amphetamine. 14 references, 2 figures, 1 table.

Reports of pathological gambling, hypersexuality, and compulsive shopping associated with dopamine receptor agonist drugs.

PubMed

Moore, Thomas J; Glenmullen, Joseph; Mattison, Donald R

2014-12-01

Severe impulse control disorders involving pathological gambling, hypersexuality, and compulsive shopping have been reported in association with the use of dopamine receptor agonist drugs in case series and retrospective patient surveys. These agents are used to treat Parkinson disease, restless leg syndrome, and hyperprolactinemia. To analyze serious adverse drug event reports about these impulse control disorders received by the US Food and Drug Administration (FDA) and to assess the relationship of these case reports with the 6 FDA-approved dopamine receptor agonist drugs. We conducted a retrospective disproportionality analysis based on the 2.7 million serious domestic and foreign adverse drug event reports from 2003 to 2012 extracted from the FDA Adverse Event Reporting System. Cases were selected if they contained any of 10 preferred terms in the Medical Dictionary for Regulatory Activities (MedDRA) that described the abnormal behaviors. We used the proportional reporting ratio (PRR) to compare the proportion of target events to all serious events for the study drugs with a similar proportion for all other drugs. We identified 1580 events indicating impulse control disorders from the United States and 21 other countries:710 fordopamine receptor agonist drugs and 870 for other drugs. The dopamine receptor agonist drugs had a strong signal associated with these impulse control disorders (n = 710; PRR = 277.6, P < .001). The association was strongest for the dopamine agonists pramipexole (n = 410; PRR = 455.9, P < .001) and ropinirole (n = 188; PRR = 152.5, P < .001), with preferential affinity for the dopamine D3 receptor. A signal was also seen for aripiprazole, an antipsychotic classified as a partial agonist of the D3 receptor (n = 37; PRR = 8.6, P < .001). Our findings confirm and extend the evidence that dopamine receptor agonist drugs are associated with these specific impulse control disorders. At present

Evolution of the Bifunctional Lead μ Agonist / δ Antagonist Containing the Dmt-Tic Opioid Pharmacophore.

PubMed

Balboni, Gianfranco; Salvadori, Severo; Trapella, Claudio; Knapp, Brian I; Bidlack, Jean M; Lazarus, Lawrence H; Peng, Xuemei; Neumeyer, John L

2010-02-17

Based on a renewed importance recently attributed to bi- or multifunctional opioids, we report the synthesis and pharmacological evaluation of some analogues derived from our lead μ agonist / δ antagonist, H-Dmt-Tic-Gly-NH-Bzl. Our previous studies focused on the importance of the C-teminal benzyl function in the induction of such bifunctional activity. The introduction of some substituents in the para position of the phenyl ring (-Cl, -CH(3), partially -NO(2), inactive -NH(2)) was found to give a more potent μ agonist / antagonist effect associated with a relatively unmodified δ antagonist activity (pA(2) = 8.28-9.02). Increasing the steric hindrance of the benzyl group (using diphenylmethyl and tetrahydroisoquinoline functionalities) substantially maintained the μ agonist and δ antagonist activities of the lead compound. Finally and quite unexpectedly D-Tic2, considered as a wrong opioid message now; inserted into the reference compound in lieu of L-Tic, provided a μ agonist / δ agonist better than our reference ligand (H-Dmt-Tic-Gly-NH-Ph) and was endowed with the same pharmacological profile.

Pharmacological characterization of 30 human melanocortin-4 receptor polymorphisms with the endogenous proopiomelanocortin-derived agonists, synthetic agonists, and the endogenous agouti-related protein antagonist.

PubMed

Xiang, Zhimin; Proneth, Bettina; Dirain, Marvin L; Litherland, Sally A; Haskell-Luevano, Carrie

2010-06-08

The melanocortin-4 receptor (MC4R) is a G-protein-coupled receptor (GPCR) that is expressed in the central nervous system and has a role in regulating feeding behavior, obesity, energy homeostasis, male erectile response, and blood pressure. Since the report of the MC4R knockout mouse in 1997, the field has been searching for links between this genetic biomarker and human obesity and type 2 diabetes. More then 80 single nucleotide polymorphisms (SNPs) have been identified from human patients, both obese and nonobese controls. Many significant studies have been performed examining the pharmacological characteristics of these hMC4R SNPs in attempts to identify a molecular defects/insights that might link a genetic factor to the obese phenotype observed in patients possessing these mutations. Our laboratory has previously reported the pharmacological characterization of 40 of these polymorphic hMC4 receptors with multiple endogenous and synthetic ligands. The goal of the current study is to perform a similar comprehensive side-by-side characterization of 30 additional human hMC4R with single nucleotide polymorphisms using multiple endogenous agonists [alpha-, beta-, and gamma(2)-melanocyte stimulating hormones (MSH) and adrenocorticotropin (ACTH)], the antagonist agouti-related protein hAGRP(87-132), and synthetic agonists [NDP-MSH, MTII, and the tetrapeptide Ac-His-dPhe-Arg-Trp-NH(2) (JRH887-9)]. These in vitro data, in some cases, provide a putative molecular link between dysfunctional hMC4R's and human obesity. These 30 hMC4R SNPs include R7H, R18H, R18L, S36Y, P48S, V50M, F51L, E61K, I69T, D90N, S94R, G98R, I121T, A154D, Y157S, W174C, G181D, F202L, A219 V, I226T, G231S, G238D, N240S, C271R, S295P, P299L, E308K, I317V, L325F, and 750DelGA. All but the N240S hMC4R were identified in obese patients. Additionally, we have characterized a double I102T/V103I hMC4R. In addition to the pharmacological characterization, the hMC4R variants were evaluated for cell surface

Synthesis and pharmacological characterization of beta2-adrenergic agonist enantiomers: zilpaterol.

PubMed

Kern, Christopher; Meyer, Thorsten; Droux, Serge; Schollmeyer, Dieter; Miculka, Christian

2009-03-26

The beta-adrenergic agonist 1 (zilpaterol) is used as production enhancer in cattle. Binding experiments of separated enantiomers on recombinant human beta(2)-adrenergic and mu-opioid receptors and functional studies showed that the (-)-1 enantiomer accounts for essentially all the beta(2)-adrenergic agonist activity and that it exhibits less affinity toward the mu-opioid receptor than (+)-1, which is a mu-opioid receptor antagonist. X-ray crystallography revealed the absolute configuration of (-)-1 to be 6R,7R.

Structural insights into selective agonist actions of tamoxifen on human estrogen receptor alpha.

PubMed

Chakraborty, Sandipan; Biswas, Pradip Kumar

2014-08-01

Tamoxifen-an anti-estrogenic ligand in breast tissues used as a first-line treatment in estrogen receptor (ER)-positive breast cancers-is associated with the development of resistance followed by resumption of tumor growth in about 30 % of cases. Whether tamoxifen assists in proliferation in such cases or whether any ligand-independent pathway to transcription exists is not fully understood; also, no ERα mutants have been detected so far that could lead to tamoxifen resistance. Using in silico conformational analysis of the ERα ligand binding domain (LBD), in the absence and presence of selective agonist (diethylstilbestrol; DES), antagonist (Faslodex; ICI), and selective estrogen receptor modulator (SERM; 4-hydroxy tamoxifen; 4-OHT) ligands, we have elucidated ligand-responsive structural modulations of the ERα-LBD dimer in its agonist and antagonist complexes to address the issue of "tamoxifen resistance". DES and ICI were found to stabilize the dimer in their agonist and antagonist conformations, respectively. The ERα-LBD dimer without the presence of any bound ligand also led to a stable structure in agonist conformation. However, binding of 4-OHT to the antagonist structure led to a flexible conformation allowing the protein to visit conformations populated by agonists as was evident from principal component analysis and radius of gyration plots. Further, the relaxed conformations of the 4-OHT bound protein exhibited a diminished size of the co-repressor binding pocket in the LBD, thus signaling a partial blockage of the co-repressor binding motif. Thus, the ability of 4-OHT-bound ERα-LBD to assume flexible conformations visited by agonists and reduced co-repressor binding surface at the LBD provide crucial structural insights into tamoxifen-resistance that complement our existing understanding.

Toll-like receptor 7 agonists are potent and rapid bronchodilators in guinea pigs

PubMed Central

Kaufman, Elad H.; Fryer, Allison D.; Jacoby, David B.

2011-01-01

Background Respiratory tract viral infections result in asthma exacerbations. Toll-like receptor (TLR) 7 is a receptor for viral single-stranded RNA and is expressed at high levels in the lungs. Objective Because TLR7 polymorphisms are associated with asthma, we examined the effects of TLR7 agonists in guinea pig airways. Methods We induced bronchoconstriction in guinea pigs in vivo by means of electrical stimulation of the vagus nerve or intravenous administration of acetylcholine and measured the effect of a TLR7 agonist administered intravenously. We induced contraction of airway smooth muscle in segments of isolated guinea pig tracheas in vitro and measured the effect of TLR7 agonists, antagonists, and pharmacologic inhibitors of associated signaling pathways administered directly to the bath. Results TLR7 agonists acutely inhibited bronchoconstriction in vivo and relaxed contraction of airway smooth muscle in vitro within minutes of administration. Airway relaxation induced by the TLR7 agonist R837 (imiquimod) was partially blocked with a TLR7 antagonist and was also blocked by inhibitors of large-conductance, calcium-activated potassium channels; prostaglandin synthesis; and nitric oxide generation. Another TLR7 agonist, 21-mer single-stranded phosphorothioated polyuridylic acid (PolyUs), mediated relaxation that was completely blocked by a TLR7 antagonist. Conclusions These data demonstrate a novel protective mechanism to limit bronchoconstriction and maintain airflow during respiratory tract viral infections. The fast time frame is inconsistent with canonical TLR7 signaling. R837 mediates bronchodilation by means of TLR7-dependent and TLR7-independent mechanisms, whereas PolyUs does so through only the TLR7-dependent mechanism. TLR7-independent mechanisms involve prostaglandins and large-conductance, calcium-activated potassium channels, whereas TLR7-dependent mechanisms involve nitric oxide. TLR7 is an attractive therapeutic target for its ability to

Gonadotropin-releasing Hormone Agonists, Orchiectomy, and Risk of Cardiovascular Disease: Semi-ecologic, Nationwide, Population-based Study.

PubMed

Thomsen, Frederik Birkebæk; Sandin, Fredrik; Garmo, Hans; Lissbrant, Ingela Franck; Ahlgren, Göran; Van Hemelrijck, Mieke; Adolfsson, Jan; Robinson, David; Stattin, Pär

2017-12-01

In observational studies, men with prostate cancer treated with gonadotropin-releasing hormone (GnRH) agonists had a higher risk of cardiovascular disease (CVD) compared to men who had undergone orchiectomy. However, selection bias may have influenced the difference in risk. To investigate the association of type of androgen deprivation therapy (ADT) with risk of CVD while minimising selection bias. Semi-ecologic study of 6556 men who received GnRH agonists and 3330 men who underwent orchiectomy as primary treatment during 1992-1999 in the Prostate Cancer Database Sweden 3.0. We measured the proportion of men who received GnRH agonists as primary treatment in 580 experimental units defined by healthcare provider, diagnostic time period, and age at diagnosis. Incident or fatal CVD events in units with high and units with low use of GnRH agonists were compared. Net and crude probabilities were also analysed. The risk of CVD was similar between units with the highest and units with the lowest proportion of GnRH agonist use (relative risk 1.01, 95% confidence interval [CI] 0.93-1.11). Accordingly, there was no difference in the net probability of CVD after GnRH agonist compared to orchiectomy (hazard ratio 1.02, 95% CI 0.96-1.09). The 10-yr crude probability of CVD was 0.56 (95% CI 0.55-0.57) for men on GnRH agonists and 0.52 (95% CI 0.50-0.54) for men treated with orchiectomy. The main limitation was the nonrandom allocation to treatment, with younger men with lower comorbidity and less advanced cancer more likely to receive GnRH agonists. Our data do not support previous observations that GnRH agonists increase the risk of CVD in comparison to orchiectomy. We found a similar risk of cardiovascular disease between medical and surgical treatment as androgen deprivation therapy for prostate cancer. Copyright © 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Dendritic cells tolerized with adenosine A2AR agonist attenuate acute kidney injury

PubMed Central

Li, Li; Huang, Liping; Ye, Hong; Song, Steven P.; Bajwa, Amandeep; Lee, Sang Ju; Moser, Emily K.; Jaworska, Katarzyna; Kinsey, Gilbert R.; Day, Yuan J.; Linden, Joel; Lobo, Peter I.; Rosin, Diane L.; Okusa, Mark D.

2012-01-01

DC-mediated NKT cell activation is critical in initiating the immune response following kidney ischemia/reperfusion injury (IRI), which mimics human acute kidney injury (AKI). Adenosine is an important antiinflammatory molecule in tissue inflammation, and adenosine 2A receptor (A2AR) agonists protect kidneys from IRI through their actions on leukocytes. In this study, we showed that mice with A2AR-deficient DCs are more susceptible to kidney IRI and are not protected from injury by A2AR agonists. In addition, administration of DCs treated ex vivo with an A2AR agonist protected the kidneys of WT mice from IRI by suppressing NKT production of IFN-γ and by regulating DC costimulatory molecules that are important for NKT cell activation. A2AR agonists had no effect on DC antigen presentation or on Tregs. We conclude that ex vivo A2AR–induced tolerized DCs suppress NKT cell activation in vivo and provide a unique and potent cell-based strategy to attenuate organ IRI. PMID:23093781

Neurotransmitter agonists inhibit inositol phosphate formation in the brain of bupropione-treated rats

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

Butler, P.D.; Hungund, B.; Suckow, R.

1986-03-05

Bupropione is a chemically unique antidepressant whose mechanism of action is not known. In this study they have evaluated the effect of chronic treatment with bupropione on the receptor-mediated release of inositol phosphates (IP) from brain slices in rats. Animals were implanted with Alzet osmotic pumps that delivered bupropione at a constant rate (40mg/kg/day) for 2 weeks. Cross-chopped slices of cerebral cortex from control and drug-treated rats were prelabelled with myo-/sup 3/H-inositol in HEPES buffer containing 11 mM LiCl. Accumulation of IP was measured in the presence and absence of the following agonists: Carbamylcholine (100..mu..m); norepinephrine (5..mu..M) and serotonin (10..mu..M).more » All agonists stimulated release of IP from slices of control animals but appeared to inhibit IP release in bupropione-treated rats. These results indicate that a phospholipase C inhibitor may appear following the activation of this enzyme by the agonist, and that the agonist-induced formation of the apparent inhibitor may be markedly enhanced after treatment with bupropione.« less

Differential effects of subtype-specific nicotinic acetylcholine receptor agonists on early and late hippocampal LTP.

PubMed

Kroker, Katja S; Rast, Georg; Rosenbrock, Holger

2011-12-05

Brain nicotinic acetylcholine receptors are involved in several neuropsychiatric disorders, e.g. Alzheimer's and Parkinson's diseases, Tourette's syndrome, schizophrenia, depression, autism, attention deficit hyperactivity disorder, and anxiety. Currently, approaches selectively targeting the activation of specific nicotinic acetylcholine receptors are in clinical development for treatment of memory impairment of Alzheimer's disease patients. These are α4β2 and α7 nicotinic acetylcholine receptor agonists which are believed to enhance cholinergic and glutamatergic neurotransmission, respectively. In order to gain a better insight into the mechanistic role of these two nicotinic acetylcholine receptors in learning and memory, we investigated the effects of the α4β2 nicotinic acetylcholine receptor agonist TC-1827 and the α7 nicotinic acetylcholine receptor partial agonist SSR180711 on hippocampal long-term potentiation (LTP), a widely accepted cellular experimental model of memory formation. Generally, LTP is distinguished in an early and a late form, the former being protein-synthesis independent and the latter being protein-synthesis dependent. TC-1827 was found to increase early LTP in a bell-shaped dose dependent manner, but did not affect late LTP. In contrast, the α7 nicotinic acetylcholine receptor partial agonist SSR180711 showed enhancing effects on both early and late LTP in a bell-shaped manner. Furthermore, SSR180711 not only increased early LTP, but also transformed it into late LTP, which was not observed with the α4β2 nicotinic acetylcholine receptor agonist. Therefore, based on these findings α7 nicotinic acetylcholine receptor (partial) agonists appear to exhibit stronger efficacy on memory improvement than α4β2 nicotinic acetylcholine receptor agonists. Copyright © 2011 Elsevier B.V. All rights reserved.

Dopamine agonist 3-PPP fails to protect against MPTP-induced toxicity.

PubMed

Muralikrishnan, Dhanasekaran; Ebadi, Manuchair; Brown-Borg, Holly M

2004-02-01

We investigated the neuroprotective effect of the dopamine agonist, 3-PPP [3-(3-hydroxyphenyl)-N-propylpiperidine] against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. MPTP (30 mg/kg, i.p., twice, 16 h apart) causes significant dopamine depletion in nucleus caudatus putamen (NCP) by 1 week. 3-PPP had no effect on the monoamine oxidase-B activity (MAO-B) activity in NCP. 3-PPP did not affect dopamine uptake, whereas mazindol significantly blocked the uptake of dopamine dose dependently. MPTP-induced behavioral changes in mice were not reduced by pretreatment with 3-PPP. This dopamine agonist did not prevent dopamine depletion caused by MPTP. MPP+ (20 microM) significantly inhibited the cell proliferation of SH-SY5Y dopaminergic neuronal cells. 3-PPP had no effect on the SH-SY5Y neuronal cell growth in culture and did not block the MPP(+)-induced cytotoxicity. This study shows that the dopamine agonist 3-PPP failed to protect against MPTP-induced dopaminergic neurotoxicity.

Increased hippocampal activation in ApoE-4 carriers and non-carriers with amnestic mild cognitive impairment.

PubMed

Tran, Tammy T; Speck, Caroline L; Pisupati, Aparna; Gallagher, Michela; Bakker, Arnold

2017-01-01

Increased fMRI activation in the hippocampus is recognized as a signature characteristic of the amnestic mild cognitive impairment (aMCI) stage of Alzheimer's disease (AD). Previous work has localized this increased activation to the dentate gyrus/CA3 subregion of the hippocampus and showed a correlation with memory impairments in those patients. Increased hippocampal activation has also been reported in carriers of the ApoE-4 allelic variation independently of mild cognitive impairment although these findings were not localized to a hippocampal subregion. To assess the ApoE-4 contribution to increased hippocampal fMRI activation, patients with aMCI genotyped for ApoE-4 status and healthy age-matched control participants completed a high-resolution fMRI scan while performing a memory task designed to tax hippocampal subregion specific functions. Consistent with previous reports, patients with aMCI showed increased hippocampal activation in the left dentate gyrus/CA3 region of the hippocampus as well as memory task errors attributable to this subregion. However, this increased fMRI activation in the hippocampus did not differ between ApoE-4 carriers and ApoE-4 non-carriers and the proportion of memory errors attributable to dentate gyrus/CA3 function did not differ between ApoE-4 carriers and ApoE-4 non-carriers. These results indicate that increased fMRI activation of the hippocampus observed in patients with aMCI is independent of ApoE-4 status and that ApoE-4 does not contribute to the dysfunctional hippocampal activation or the memory errors attributable to this subregion in these patients.

Glymphatic distribution of CSF-derived apoE into brain is isoform specific and suppressed during sleep deprivation.

PubMed

Achariyar, Thiyagaragan M; Li, Baoman; Peng, Weiguo; Verghese, Philip B; Shi, Yang; McConnell, Evan; Benraiss, Abdellatif; Kasper, Tristan; Song, Wei; Takano, Takahiro; Holtzman, David M; Nedergaard, Maiken; Deane, Rashid

2016-12-08

Apolipoprotein E (apoE) is a major carrier of cholesterol and essential for synaptic plasticity. In brain, it's expressed by many cells but highly expressed by the choroid plexus and the predominant apolipoprotein in cerebrospinal fluid (CSF). The role of apoE in the CSF is unclear. Recently, the glymphatic system was described as a clearance system whereby CSF and ISF (interstitial fluid) is exchanged via the peri-arterial space and convective flow of ISF clearance is mediated by aquaporin 4 (AQP4), a water channel. We reasoned that this system also serves to distribute essential molecules in CSF into brain. The aim was to establish whether apoE in CSF, secreted by the choroid plexus, is distributed into brain, and whether this distribution pattern was altered by sleep deprivation. We used fluorescently labeled lipidated apoE isoforms, lenti-apoE3 delivered to the choroid plexus, immunohistochemistry to map apoE brain distribution, immunolabeled cells and proteins in brain, Western blot analysis and ELISA to determine apoE levels and radiolabeled molecules to quantify CSF inflow into brain and brain clearance in mice. Data were statistically analyzed using ANOVA or Student's t- test. We show that the glymphatic fluid transporting system contributes to the delivery of choroid plexus/CSF-derived human apoE to neurons. CSF-delivered human apoE entered brain via the perivascular space of penetrating arteries and flows radially around arteries, but not veins, in an isoform specific manner (apoE2 > apoE3 > apoE4). Flow of apoE around arteries was facilitated by AQP4, a characteristic feature of the glymphatic system. ApoE3, delivered by lentivirus to the choroid plexus and ependymal layer but not to the parenchymal cells, was present in the CSF, penetrating arteries and neurons. The inflow of CSF, which contains apoE, into brain and its clearance from the interstitium were severely suppressed by sleep deprivation compared to the sleep state. Thus, choroid plexus

A Dietary Treatment Improves Cerebral Blood Flow and Brain Connectivity in Aging apoE4 Mice

PubMed Central

Wiesmann, Maximilian; Zerbi, Valerio; Jansen, Diane; Haast, Roy; Lütjohann, Dieter; Broersen, Laus M.; Heerschap, Arend

2016-01-01

APOE ε4 (apoE4) polymorphism is the main genetic determinant of sporadic Alzheimer's disease (AD). A dietary approach (Fortasyn) including docosahexaenoic acid, eicosapentaenoic acid, uridine, choline, phospholipids, folic acid, vitamins B12, B6, C, and E, and selenium has been proposed for dietary management of AD. We hypothesize that the diet could inhibit AD-like pathologies in apoE4 mice, specifically cerebrovascular and connectivity impairment. Moreover, we evaluated the diet effect on cerebral blood flow (CBF), functional connectivity (FC), gray/white matter integrity, and postsynaptic density in aging apoE4 mice. At 10–12 months, apoE4 mice did not display prominent pathological differences compared to wild-type (WT) mice. However, 16–18-month-old apoE4 mice revealed reduced CBF and accelerated synaptic loss. The diet increased cortical CBF and amount of synapses and improved white matter integrity and FC in both aging apoE4 and WT mice. We demonstrated that protective mechanisms on vascular and synapse health are enhanced by Fortasyn, independent of apoE genotype. We further showed the efficacy of a multimodal translational approach, including advanced MR neuroimaging, to study dietary intervention on brain structure and function in aging. PMID:27034849

GnRH agonist versus GnRH antagonist in ovarian stimulation: is the emperor naked?

PubMed

Orvieto, R; Rabinson, J; Meltzer, S; Homburg, R; Anteby, E; Zohav, E

2006-01-01

The aim of the study was to evaluate the influence of type of GnRH-analog used during controlled ovarian hyperstimulation (COH) on the outcome of in vitro fertilization (IVF) cycles. All consecutive women aged < or = 35 years admitted to our IVF unit from January 2001 to December 2004 were enrolled in the study. Only patients undergoing up to their third IVF cycle attempt were included. Ovarian stimulation characteristics, number of oocytes retrieved, number of embryos transferred, and clinical pregnancy rate were compared between women given GnRH-agonist or GnRH-antagonist during COH. Four hundred and eighty-seven consecutive IVF cycles were evaluated, 226 in the agonist group and 261 in the antagonist group. A clinical pregnancy was achieved in 93 patients in the agonist group (pregnancy rate 41.2% per cycle) and 66 patients in the antagonist grup (pregnancy rate 25.3%); this difference was statistically significant (p < 0.01). The agonist group also used significantly more gonadotropin ampoules, required longer stimulation, and had higher estradiol levels on the day of human chorionic gonadotropin administration. The midluteal long GhRH-agonist suppressive protocol should be the protocol of choice in young patients in their first three IVF cycle attempts.

Longitudinal Links between Fathers&apos; and Mothers&apos; Harsh Verbal Discipline and Adolescents&apos; Conduct Problems and Depressive Symptoms

ERIC Educational Resources Information Center

Wang, Ming-Te; Kenny, Sarah

2014-01-01

This study used cross-lagged modeling to examine reciprocal relations between maternal and paternal harsh verbal discipline and adolescents&apos; conduct problems and depressive symptoms. Data were from a sample of 976 two-parent families and their children (51% males; 54% European American, 40% African American). Mothers&apos; and fathers&apos;…

Rate constants of agonist binding to muscarinic receptors in rat brain medulla. Evaluation by competition kinetics

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

Schreiber, G.; Henis, Y.I.; Sokolovsky, M.

The method of competition kinetics, which measures the binding kinetics of an unlabeled ligand through its effect on the binding kinetics of a labeled ligand, was employed to investigate the kinetics of muscarinic agonist binding to rat brain medulla pons homogenates. The agonists studied were acetylcholine, carbamylcholine, and oxotremorine, with N-methyl-4-(TH)piperidyl benzilate employed as the radiolabeled ligand. Our results suggested that the binding of muscarinic agonists to the high affinity sites is characterized by dissociation rate constants higher by 2 orders of magnitude than those of antagonists, with rather similar association rate constants. Our findings also suggest that isomerization ofmore » the muscarinic receptors following ligand binding is significant in the case of antagonists, but not of agonists. Moreover, it is demonstrated that in the medulla pons preparation, agonist-induced interconversion between high and low affinity bindings sites does not occur to an appreciable extent.« less

High-Fat Diet Changes Hippocampal Apolipoprotein E (ApoE) in a Genotype- and Carbohydrate-Dependent Manner in Mice.

PubMed

Lane-Donovan, Courtney; Herz, Joachim

2016-01-01

Alzheimer's disease is a currently incurable neurodegenerative disease affecting millions of individuals worldwide. Risk factors for Alzheimer's disease include genetic risk factors, such as possession of ε4 allele of apolipoprotein E (ApoE4) over the risk-neutral ApoE3 allele, and lifestyle risk factors, such as diet and exercise. The intersection of these two sources of disease risk is not well understood. We investigated the impact of diet on ApoE levels by feeding wildtype, ApoE3, and ApoE4 targeted replacement (TR) mice with chow, high-fat, or ketogenic (high-fat, very-low-carbohydrate) diets. We found that high-fat diet affected both plasma and hippocampal levels of ApoE in an isoform-dependent manner, with high-fat diet causing a surprising reduction of hippocampal ApoE levels in ApoE3 TR mice. Conversely, the ketogenic diet had no effect on hippocampal ApoE. Our findings suggest that the use of dietary interventions to slow the progression AD should take ApoE genotype into consideration.

High-Fat Diet Changes Hippocampal Apolipoprotein E (ApoE) in a Genotype- and Carbohydrate-Dependent Manner in Mice

PubMed Central

Lane-Donovan, Courtney; Herz, Joachim

2016-01-01

Alzheimer’s disease is a currently incurable neurodegenerative disease affecting millions of individuals worldwide. Risk factors for Alzheimer’s disease include genetic risk factors, such as possession of ε4 allele of apolipoprotein E (ApoE4) over the risk-neutral ApoE3 allele, and lifestyle risk factors, such as diet and exercise. The intersection of these two sources of disease risk is not well understood. We investigated the impact of diet on ApoE levels by feeding wildtype, ApoE3, and ApoE4 targeted replacement (TR) mice with chow, high-fat, or ketogenic (high-fat, very-low-carbohydrate) diets. We found that high-fat diet affected both plasma and hippocampal levels of ApoE in an isoform-dependent manner, with high-fat diet causing a surprising reduction of hippocampal ApoE levels in ApoE3 TR mice. Conversely, the ketogenic diet had no effect on hippocampal ApoE. Our findings suggest that the use of dietary interventions to slow the progression AD should take ApoE genotype into consideration. PMID:26828652

Identification of PPARgamma Partial Agonists of Natural Origin (I): Development of a Virtual Screening Procedure and In Vitro Validation

PubMed Central

Guasch, Laura; Sala, Esther; Castell-Auví, Anna; Cedó, Lidia; Liedl, Klaus R.; Wolber, Gerhard; Muehlbacher, Markus; Mulero, Miquel; Pinent, Montserrat; Ardévol, Anna; Valls, Cristina; Pujadas, Gerard; Garcia-Vallvé, Santiago

2012-01-01

Background Although there are successful examples of the discovery of new PPARγ agonists, it has recently been of great interest to identify new PPARγ partial agonists that do not present the adverse side effects caused by PPARγ full agonists. Consequently, the goal of this work was to design, apply and validate a virtual screening workflow to identify novel PPARγ partial agonists among natural products. Methodology/Principal Findings We have developed a virtual screening procedure based on structure-based pharmacophore construction, protein-ligand docking and electrostatic/shape similarity to discover novel scaffolds of PPARγ partial agonists. From an initial set of 89,165 natural products and natural product derivatives, 135 compounds were identified as potential PPARγ partial agonists with good ADME properties. Ten compounds that represent ten new chemical scaffolds for PPARγ partial agonists were selected for in vitro biological testing, but two of them were not assayed due to solubility problems. Five out of the remaining eight compounds were confirmed as PPARγ partial agonists: they bind to PPARγ, do not or only moderately stimulate the transactivation activity of PPARγ, do not induce adipogenesis of preadipocyte cells and stimulate the insulin-induced glucose uptake of adipocytes. Conclusions/Significance We have demonstrated that our virtual screening protocol was successful in identifying novel scaffolds for PPARγ partial agonists. PMID:23226391

Individual Differences in Children&apos;s and Parents&apos; Generic Language

ERIC Educational Resources Information Center

Gelman, Susan A.; Ware, Elizabeth A.; Kleinberg, Felicia; Manczak, Erika M.; Stilwell, Sarah M.

2014-01-01

Generics ("&apos;Dogs&apos; bark") convey important information about categories and facilitate children&apos;s learning. Two studies with parents and their 2- or 4-year-old children (N = 104 dyads) examined whether individual differences in generic language use are as follows: (a) stable over time, contexts, and domains, and (b) linked…

Regulation of p53 Stability and Apoptosis by a ROR Agonist

PubMed Central

Wang, Yongjun; Solt, Laura A.; Kojetin, Douglas J.; Burris, Thomas P.

2012-01-01

Activation of p53 function leading to cell-cycle arrest and/or apoptosis is a promising strategy for development of anti-cancer therapeutic agents. Here, we describe a novel mechanism for stabilization of p53 protein expression via activation of the orphan nuclear receptor, RORα. We demonstrate that treatment of cancer cells with a newly described synthetic ROR agonist, SR1078, leads to p53 stabilization and induction of apoptosis. These data suggest that synthetic ROR agonists may hold utility in the treatment of cancer. PMID:22509368

Regulation of p53 stability and apoptosis by a ROR agonist.

PubMed

Wang, Yongjun; Solt, Laura A; Kojetin, Douglas J; Burris, Thomas P

2012-01-01

Activation of p53 function leading to cell-cycle arrest and/or apoptosis is a promising strategy for development of anti-cancer therapeutic agents. Here, we describe a novel mechanism for stabilization of p53 protein expression via activation of the orphan nuclear receptor, RORα. We demonstrate that treatment of cancer cells with a newly described synthetic ROR agonist, SR1078, leads to p53 stabilization and induction of apoptosis. These data suggest that synthetic ROR agonists may hold utility in the treatment of cancer.

Discovery of 3-aryl-4-isoxazolecarboxamides as TGR5 receptor agonists.

PubMed

Evans, Karen A; Budzik, Brian W; Ross, Sean A; Wisnoski, David D; Jin, Jian; Rivero, Ralph A; Vimal, Mythily; Szewczyk, George R; Jayawickreme, Channa; Moncol, David L; Rimele, Thomas J; Armour, Susan L; Weaver, Susan P; Griffin, Robert J; Tadepalli, Sarva M; Jeune, Michael R; Shearer, Todd W; Chen, Zibin B; Chen, Lihong; Anderson, Donald L; Becherer, J David; De Los Frailes, Maite; Colilla, Francisco Javier

2009-12-24

A series of 3-aryl-4-isoxazolecarboxamides identified from a high-throughput screening campaign as novel, potent small molecule agonists of the human TGR5 G-protein coupled receptor is described. Subsequent optimization resulted in the rapid identification of potent exemplars 6 and 7 which demonstrated improved GLP-1 secretion in vivo via an intracolonic dose coadministered with glucose challenge in a canine model. These novel TGR5 receptor agonists are potentially useful therapeutics for metabolic disorders such as type II diabetes and its associated complications.

Peroxidative Metabolism of β2-Agonists Salbutamol and Fenoterol and Their Analogs

PubMed Central

Reszka, Krzysztof J.; McGraw, Dennis W.; Britigan, Bradley E.

2009-01-01

Phenolic β2-adrenoreceptor agonists salbutamol, fenoterol and terbutaline relax smooth muscle cells that relieve acute airway bronchospasm associated with asthma. Why their use sometimes fails to relieve bronchospasm, and why the drugs appear to be less effective in patients with severe asthma exacerbations, remains unclear. We show that in the presence of hydrogen peroxide, both myeloperoxidase, secreted by activated neutrophils present in inflamed airways, and lactoperoxidase, which is naturally present in the respiratory system, catalyze oxidation of these β2-agonists. Azide, cyanide, thiocyanate, ascorbate, glutathione, and methimazole inhibited this process, while methionine was without effect. Inhibition by ascorbate and glutathione was associated with their oxidation to corresponding radical species by the agonists’-derived phenoxyl radicals. Using electron paramagnetic resonance (EPR), we detected free radical metabolites from β2-agonists by spin trapping with 2-methyl-2-nitrosopropane (MNP). Formation of these radicals was inhibited by pharmacologically-relevant concentrations of methimazole and dapsone. In alkaline buffers radicals from fenoterol and its structural analog, metaproteronol, were detected by direct EPR. Analysis of these spectra suggests that oxidation of fenoterol and metaproterenol, but not terbutaline, causes their transformation through intramolecular cyclization by addition of their amino nitrogen to the aromatic ring. Together, these results indicate that phenolic β2-agonists function as substrates for airway peroxidases and that the resulting products differ in their structural and functional properties from their parent compounds. They also suggest that these transformations can be modulated by pharmacological approaches using appropriate peroxidase inhibitors or alternative substrates. These processes may affect therapeutic efficacy and also play a role in adverse reactions of the β2-agonists. PMID:19462961

Oxytocin and Vasopressin Agonists and Antagonists as Research Tools and Potential Therapeutics

PubMed Central

Manning, M; Misicka, A; Olma, A; Bankowski, K; Stoev, S; Chini, B; Durroux, T; Mouillac, B; Corbani, M; Guillon, G

2012-01-01

We recently reviewed the status of peptide and nonpeptide agonists and antagonists for the V1a, V1b and V2 receptors for arginine vasopressin (AVP) and the oxytocin receptor for oxytocin (OT). In the present review, we update the status of peptides and nonpeptides as: (i) research tools and (ii) therapeutic agents. We also present our recent findings on the design of fluorescent ligands for V1b receptor localisation and for OT receptor dimerisation. We note the exciting discoveries regarding two novel naturally occurring analogues of OT. Recent reports of a selective VP V1a agonist and a selective OT agonist point to the continued therapeutic potential of peptides in this field. To date, only two nonpeptides, the V2/V1a antagonist, conivaptan and the V2 antagonist tolvaptan have received Food and Drug Administration approval for clinical use. The development of nonpeptide AVP V1a, V1b and V2 antagonists and OT agonists and antagonists has recently been abandoned by Merck, Sanofi and Pfizer. A promising OT antagonist, Retosiban, developed at Glaxo SmithKline is currently in a Phase II clinical trial for the prevention of premature labour. A number of the nonpeptide ligands that were not successful in clinical trials are proving to be valuable as research tools. Peptide agonists and antagonists continue to be very widely used as research tools in this field. In this regard, we present receptor data on some of the most widely used peptide and nonpeptide ligands, as a guide for their use, especially with regard to receptor selectivity and species differences. PMID:22375852

Discovery of novel acetanilide derivatives as potent and selective beta3-adrenergic receptor agonists.

PubMed

Maruyama, Tatsuya; Onda, Kenichi; Hayakawa, Masahiko; Matsui, Tetsuo; Takasu, Toshiyuki; Ohta, Mitsuaki

2009-06-01

In the search for potent and selective human beta3-adrenergic receptor (AR) agonists as potential drugs for the treatment of obesity and noninsulin-dependent (type II) diabetes, a novel series of acetanilide-based analogues were prepared and their biological activities were evaluated at the human beta3-, beta2-, and beta1-ARs. Among these compounds, 2-pyridylacetanilide (2f), pyrimidin-2-ylacetanilide (2u), and pyrazin-2-ylacetanilide (2v) derivatives exhibited potent agonistic activity at the beta3-AR with functional selectivity over the beta1- and beta2-ARs. In particular, compound 2u was found to be the most potent and selective beta3-AR agonist with an EC(50) value of 0.11 microM and no agonistic activity for either the beta1- or beta2-AR. In addition, 2f, 2u, and 2v showed significant hypoglycemic activity in a rodent diabetic model.

Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.

2003-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate CAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of CAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of CAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of CAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of CAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of CAMP by either epinephrine or isoproterenol.

Why Was Kelvin&apos;s Estimate of the Earth&apos;s Age Wrong?

ERIC Educational Resources Information Center

Lovatt, Ian; Syed, M. Qasim

2014-01-01

This is a companion to our previous paper in which we give a published example, based primarily on Perry&apos;s work, of a graph of ln "y" versus "t" when "y" is an exponential function of "t". This work led us to the idea that Lord Kelvin&apos;s (William Thomson&apos;s) estimate of the Earth&apos;s age was…

Newspapers and Newspaper Ink Contain Agonists for the Ah Receptor

PubMed Central

Bohonowych, Jessica E. S.; Zhao, Bin; Timme-Laragy, Alicia; Jung, Dawoon; Di Giulio, Richard T.; Denison, Michael S.

2010-01-01

Ligand-dependent activation of the aryl hydrocarbon receptor (AhR) pathway leads to a diverse array of biological and toxicological effects. The best-studied ligands for the AhR include polycyclic and halogenated aromatic hydrocarbons, the most potent of which is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, as new AhR ligands are identified and characterized, their structural and physiochemical diversity continues to expand. Our identification of AhR agonists in crude extracts from diverse materials raises questions as to the magnitude and extent of human exposure to AhR ligands through normal daily activities. We have found that solvent extracts of newspapers from countries around the world stimulate the AhR signaling pathway. AhR agonist activity was observed for dimethyl sulfoxide (DMSO), ethanol, and water extracts of printed newspaper, unprinted virgin paper, and black printing ink, where activation of luciferase reporter gene expression was transient, suggesting that the AhR active chemical(s) was metabolically labile. DMSO and ethanol extracts also stimulated AhR transformation and DNA binding, and also competed with [3H]TCDD for binding to the AhR. In addition, DMSO extracts of printed newspaper induced cytochrome P450 1A associated 7-ethoxyresorufin-O-deethylase activity in zebrafish embryos in vivo. Although the responsible bioactive chemical(s) remain to be identified, our results demonstrate that newspapers and printing ink contain relatively potent metabolically labile agonists of the AhR. Given the large amount of recycling and reprocessing of newspapers throughout the world, release of these easily extractable AhR agonists into the environment should be examined and their potential effects on aquatic organisms assessed. PMID:18203687

A Human Platelet Calcium Calculator Trained by Pairwise Agonist Scanning

PubMed Central

Lee, Mei Yan; Diamond, Scott L.

2015-01-01

Since platelet intracellular calcium mobilization [Ca(t)]i controls granule release, cyclooxygenase-1 and integrin activation, and phosphatidylserine exposure, blood clotting simulations require prediction of platelet [Ca(t)]i in response to combinatorial agonists. Pairwise Agonist Scanning (PAS) deployed all single and pairwise combinations of six agonists (ADP, convulxin, thrombin, U46619, iloprost and GSNO used at 0.1, 1, and 10xEC50; 154 conditions including a null condition) to stimulate platelet P2Y1/P2Y12 GPVI, PAR1/PAR4, TP, IP receptors, and guanylate cyclase, respectively, in Factor Xa-inhibited (250 nM apixaban), diluted platelet rich plasma that had been loaded with the calcium dye Fluo-4 NW. PAS of 10 healthy donors provided [Ca(t)]i data for training 10 neural networks (NN, 2-layer/12-nodes) per donor. Trinary stimulations were then conducted at all 0.1x and 1xEC50 doses (160 conditions) as was a sampling of 45 higher ordered combinations (four to six agonists). The NN-ensemble average was a calcium calculator that accurately predicted [Ca (t)]i beyond the single and binary training set for trinary stimulations (R = 0.924). The 160 trinary synergy scores, a normalized metric of signaling crosstalk, were also well predicted (R = 0.850) as were the calcium dynamics (R = 0.871) and high-dimensional synergy scores (R = 0.695) for the 45 higher ordered conditions. The calculator even predicted sequential addition experiments (n = 54 conditions, R = 0.921). NN-ensemble is a fast calcium calculator, ideal for multiscale clotting simulations that include spatiotemporal concentrations of ADP, collagen, thrombin, thromboxane, prostacyclin, and nitric oxide. PMID:25723389

Neonatal (+)-methamphetamine exposure in rats alters adult locomotor responses to dopamine D1 and D2 agonists and to a glutamate NMDA receptor antagonist, but not to serotonin agonists

PubMed Central

Graham, Devon L.; Amos-Kroohs, Robyn M.; Braun, Amanda A.; Grace, Curtis E.; Schaefer, Tori L.; Skelton, Matthew R.; Williams, Michael T.; Vorhees, Charles V.

2015-01-01

Neonatal exposure to (+)-methamphetamine (Meth) results in long-term behavioural abnormalities but its developmental mechanisms are unknown. In a series of experiments, rats were treated from post-natal days (PD) 11–20 (stage that approximates human development from the second to third trimester) with Meth or saline and assessed using locomotor activity as the readout following pharmacological challenge doses with dopamine, serotonin and glutamate agonists or antagonists during adulthood. Exposure to Meth early in life resulted in an exaggerated adult locomotor hyperactivity response to the dopamine D1 agonist SKF-82958 at multiple doses, a high dose only under-response activating effect of the D2 agonist quinpirole, and an exaggerated under-response to the activating effect of the N-methyl-D-aspartic acid (NMDA) receptor antagonist, MK-801. No change in locomotor response was seen following challenge with the 5-HT releaser p-chloroamphetamine or the 5-HT2/3 receptor agonist, quipazine. These are the first data to show that PD 11-20 Meth exposure induces long-lasting alterations to dopamine D1, D2 and glutamate NMDA receptor function and may suggest how developmental Meth exposure leads to many of its long-term adverse effects. PMID:22391043

Gonadotropin-releasing Hormone Agonist Overuse: Urologists’ Response to Reimbursement and Characteristics Associated with Persistent Overuse

PubMed Central

Ellis, Shellie D.; Nielsen, Matthew E.; Carpenter, William R.; Jackson, George L.; Wheeler, Stephanie B.; Liu, Huan; Weinberger, Morris

2015-01-01

BACKGROUND Medicare reimbursement cuts have been associated with declining Gonadotropin-releasing Hormone (GnRH) agonist overuse in localized prostate cancer. Medical school affiliation and foreign training have been associated with persistent overuse. However, physician-level prescribing changes and the practice type of persistent overusers have not been examined. We sought to describe physician-level changes in GnRH agonist overuse and test the association of time in practice and solo practice type with GnRH agonist overuse. METHODS We matched American Medical Association physician data for 2,138 urologists to SEER–Medicare data for 12,943 men diagnosed with early stage and lower grade adenocarcinoma of the prostate between 2000 and 2007. We conducted a population-based, retrospective study using multi-level modeling to control for patient and provider characteristics. RESULTS Three distinct patterns of GnRH agonist overuse were observed. Urologists’ time in practice was not associated with GnRH agonist overuse (OR 0.89; 95% CI 0.75–1.05).However, solo practice type (OR 1.65; 95% CI 1.34–2.02), medical school affiliation (OR 0.65; 95% CI 0.55–0.77), and patient race were. Compared to non-Hispanic whites, non-Hispanic blacks (OR 1.76; 95% CI 1.37–2.27), Hispanics (OR 1.41; 95% CI 1.12–1.79) and men of “other” race (OR 1.44; 95% CI 1.04–1.99) had greater odds of receiving unnecessary GnRH agonists. CONCLUSIONS GnRH agonist overuse remains high among some urologists who may be professionally isolated and difficult to reach. These urologists treat more vulnerable populations, which may contribute to health disparities in prostate cancer treatment quality. Nonetheless, these findings provide guidance to develop interventions to address overuse in prostate cancer. PMID:25849354

A molecular characterization of the agonist binding site of a nematode cys-loop GABA receptor

PubMed Central

Kaji, Mark D; Kwaka, Ariel; Callanan, Micah K; Nusrat, Humza; Desaulniers, Jean-Paul; Forrester, Sean G

2015-01-01

Background and Purpose Cys-loop GABA receptors represent important targets for human chemotherapeutics and insecticides and are potential targets for novel anthelmintics (nematicides). However, compared with insect and mammalian receptors, little is known regarding the pharmacological characteristics of nematode Cys-loop GABA receptors. Here we have investigated the agonist binding site of the Cys-loop GABA receptor UNC-49 (Hco-UNC-49) from the parasitic nematode Haemonchus contortus. Experimental Approach We used two-electrode voltage-clamp electrophysiology to measure channel activation by classical GABA receptor agonists on Hco-UNC-49 expressed in Xenopus laevis oocytes, along with site-directed mutagenesis and in silico homology modelling. Key Results The sulphonated molecules P4S and taurine had no effect on Hco-UNC-49. Other classical Cys-loop GABAA receptor agonists tested on the Hco-UNC-49B/C heteromeric channel had a rank order efficacy of GABA > trans-4-aminocrotonic acid > isoguvacine > imidazole-4-acetic acid (IMA) > (R)-(−)-4-amino-3-hydroxybutyric acid [R(−)-GABOB] > (S)-(+)-4-amino-3-hydroxybutyric acid [S(+)-GABOB] > guanidinoacetic acid > isonipecotic acid > 5-aminovaleric acid (DAVA) (partial agonist) > β-alanine (partial agonist). In silico ligand docking revealed some variation in binding between agonists. Mutagenesis of a key serine residue in binding loop C to threonine had minimal effects on GABA and IMA but significantly increased the maximal response to DAVA and decreased twofold the EC50 for R(−)- and S(+)-GABOB. Conclusions and Implications The pharmacological profile of Hco-UNC-49 differed from that of vertebrate Cys-loop GABA receptors and insect resistance to dieldrin receptors, suggesting differences in the agonist binding pocket. These findings could be exploited to develop new drugs that specifically target GABA receptors of parasitic nematodes. PMID:25850584

Metformin sensitizes triple-negative breast cancer to proapoptotic TRAIL receptor agonists by suppressing XIAP expression.

PubMed

Strekalova, Elena; Malin, Dmitry; Rajanala, Harisha; Cryns, Vincent L

2017-06-01

Despite robust antitumor activity in diverse preclinical models, TNF-related apoptosis-inducing ligand (TRAIL) receptor agonists have not demonstrated efficacy in clinical trials, underscoring the need to identify agents that enhance their activity. We postulated that the metabolic stress induced by the diabetes drug metformin would sensitize breast cancer cells to TRAIL receptor agonists. Human triple (estrogen receptor, progesterone receptor, and HER2)-negative breast cancer (TNBC) cell lines were treated with TRAIL receptor agonists (monoclonal antibodies or TRAIL peptide), metformin, or the combination. The effects on cell survival, caspase activation, and expression of TRAIL receptors and the antiapoptotic protein XIAP were determined. In addition, XIAP was silenced by RNAi in TNBC cells and the effects on sensitivity to TRAIL were determined. The antitumor effects of metformin, TRAIL, or the combination were evaluated in an orthotopic model of metastatic TNBC. Metformin sensitized diverse TNBC cells to TRAIL receptor agonists. Metformin selectively enhanced the sensitivity of transformed breast epithelial cells to TRAIL receptor agonist-induced caspase activation and apoptosis with little effect on untransformed breast epithelial cells. These effects of metformin were accompanied by robust reductions in the protein levels of XIAP, a negative regulator of TRAIL-induced apoptosis. Silencing XIAP in TNBC cells mimicked the TRAIL-sensitizing effects of metformin. Metformin also enhanced the antitumor effects of TRAIL in a metastatic murine TNBC model. Our findings indicate that metformin enhances the activity of TRAIL receptor agonists, thereby supporting the rationale for additional translational studies combining these agents.

Molecular interactions of agonist and inverse agonist ligands at serotonin 5-HT2C G protein-coupled receptors: computational ligand docking and molecular dynamics studies validated by experimental mutagenesis results

NASA Astrophysics Data System (ADS)

Córdova-Sintjago, Tania C.; Liu, Yue; Booth, Raymond G.

2015-02-01

To understand molecular determinants for ligand activation of the serotonin 5-HT2C G protein-coupled receptor (GPCR), a drug target for obesity and neuropsychiatric disorders, a 5-HT2C homology model was built according to an adrenergic β2 GPCR (β2AR) structure and validated using a 5-HT2B GPCR crystal structure. The models were equilibrated in a simulated phosphatidyl choline membrane for ligand docking and molecular dynamics studies. Ligands included (2S, 4R)-(-)-trans-4-(3'-bromo- and trifluoro-phenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalene-2-amine (3'-Br-PAT and 3'-CF3-PAT), a 5-HT2C agonist and inverse agonist, respectively. Distinct interactions of 3'-Br-PAT and 3'-CF3-PAT at the wild-type (WT) 5-HT2C receptor model were observed and experimental 5-HT2C receptor mutagenesis studies were undertaken to validate the modelling results. For example, the inverse agonist 3'-CF3-PAT docked deeper in the WT 5-HT2C binding pocket and altered the orientation of transmembrane helices (TM) 6 in comparison to the agonist 3'-Br-PAT, suggesting that changes in TM orientation that result from ligand binding impact function. For both PATs, mutation of 5-HT2C residues S3.36, T3.37, and F5.47 to alanine resulted in significantly decreased affinity, as predicted from modelling results. It was concluded that upon PAT binding, 5-HT2C residues T3.37 and F5.47 in TMs 3 and 5, respectively, engage in inter-helical interactions with TMs 4 and 6, respectively. The movement of TMs 5 and 6 upon agonist and inverse agonist ligand binding observed in the 5-HT2C receptor modelling studies was similar to movements reported for the activation and deactivation of the β2AR, suggesting common mechanisms among aminergic neurotransmitter GPCRs.

Co-administration of delta- and mu-opioid receptor agonists promotes peripheral opioid receptor function

PubMed Central

Schramm, Cicely L.; Honda, Christopher N.

2010-01-01

Enhancement of peripheral opioid analgesia following tissue injury or inflammation in animal models is well-documented, but clinical results of peripheral opioid therapy remain inconsistent. Previous studies in the central nervous system have shown that co-administration of μ- and δ-opioid receptor agonists can enhance analgesic outcomes; however, less is known about the functional consequences of opioid receptor interactions in the periphery. The present study examines the effects of intraplantar injection of the μ- and δ-opioid receptor agonists, morphine and deltorphin, alone and in combination on behavioral tests of nociception in naïve rats and on potassium-evoked release of CGRP from sciatic nerves of naïve rats. Neither drug alone affected nociceptive behaviors or CGRP release. Two separate measures of mechanical nociceptive sensitivity remained unchanged after co-administration of the two drugs. In contrast, when deltorphin was co-injected with morphine, dose-dependent and peripherally-restricted increases in paw withdrawal latencies to radiant heat were observed. Similarly, concentration-dependent inhibition of CGRP release was observed when deltorphin and morphine were administered in sequence prior to potassium stimulation. However, no inhibition was observed when morphine was administered prior to deltorphin. All combined opioid effects were blocked by co-application of antagonists. Deltorphin exposure also enhanced the in vivo and in vitro effects of another μ-opioid receptor agonist, DAMGO. Together, these results suggest that under normal conditions, δ-opioid receptor agonists enhance the effect of μ-opioid receptor agonists in the periphery, and local co-administration of δ- and μ-opioid receptor agonists may improve results of peripheral opioid therapy for the treatment of pain. PMID:20970925

Drugs for metabolic conditions and prostate cancer death in men on GnRH agonists.

PubMed

Bosco, Cecilia; Wong, Chloe; Garmo, Hans; Crawley, Danielle; Holmberg, Lars; Hammar, Niklas; Adolfsson, Jan; Stattin, Pär; Van Hemelrijck, Mieke

2018-02-01

To evaluate whether drugs for metabolic conditions influence prostate cancer-specific mortality in men starting gonadotrophin-releasing hormone (GnRH) agonists, as it is unclear whether metabolic syndrome and its related drugs is affecting treatment response in men with prostate cancer on GnRH agonists. We selected all men receiving GnRH agonists as primary treatment in the Prostate Cancer data Base Sweden (PCBaSe) (n = 9267). Use of drugs for metabolic conditions (i.e. anti-diabetes, anti-dyslipidaemia, and antihypertension) in relation to all-cause, cardiovascular disease (CVD), and prostate cancer-specific death were studied using multivariate Cox proportional hazard and Fine and Gray competing regression models. In all, 6322 (68%) men used at least one drug for a metabolic condition at GnRH agonist initiation: 46% on antihypertensive drugs only, 32% on drugs for dyslipidaemia and hypertension, and ~10% on drugs for more than two metabolic conditions. Cox models indicated a weak increased risk of prostate cancer death in men who were on drugs for hypertension only (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.03-1.23) or drugs for hyperglycaemia (HR 1.19, 95% CI 1.06-1.35) at GnRH agonist initiation. However, upon taking into account competing risk from CVD death, none of the drugs for metabolic conditions were associated with an increased risk of prostate cancer death. We did not find evidence for a better or worse response to GnRH agonists in men with prostate cancer who were also on drugs for hypertension, dyslipidaemia, or hyperglycaemia. © 2017 The Authors BJU International © 2017 BJU International Published by John Wiley & Sons Ltd.

Additive melanoma suppression with intralesional phospholipid conjugated TLR7 agonists and systemic IL-2

PubMed Central

Hayashi, Tomoko; Chan, Michael; Norton, John T.; Wu, Christina C.N.; Yao, Shiyin; Cottam, Howard B.; Tawatao, Rommel I.; Corr, Maripat; Carson, Dennis A; Daniels, Gregory A.

2010-01-01

Objective There remains a compelling need for the development of treatments for unresectable melanoma. Agents that stimulate the innate immune response could provide advantages for cell based therapies. However there are conflicting reports concerning whether Toll-like receptor (TLR) signaling controls tumor growth. The objective of this study was to evaluate the effect of the intralesional administration of a TLR7 agonist in melanoma therapy. Methods B16cOVA melanoma was implanted to TLR7−/− mice to evaluate the roles of stromal TLR7 on melanoma growth. To capitalize on the potential deleterious effects of TLR7 stimulation on tumor growth, we injected melanoma tumor nodules with a newly developed and potent TLR7 agonist. Results B16 melanoma nodules expanded more rapidly in mice deficient in TLR7- and MyD88- compared to TLR9-deficient and wild type mice. Repeated injections with low doses of unconjugated TLR7 agonist were more effective at attenuating nodule size than a single high dose injection. To improve efficacy we conjugated the agonist to phospholipid or polyethylene glycol-phospholipid, which retained TLR7 specificity. The phospholipid conjugate was indeed more effective in reducing lesion size. Furthermore intralesional administration of the phospholipid TLR7 agonist conjugate enhanced the anti-melanoma effects of systemic IL-2 treatment and prolonged the survival of mice compared to IL-2 alone. Conclusion TLR7/MyD88 signaling in the stroma is involved in melanoma growth. Intralesional administration of a TLR7 agonist reduces the growth of melanoma nodules and enhances the anti-melanoma effects of IL-2. PMID:21030882

Assembly of high-affinity insulin receptor agonists and antagonists from peptide building blocks

PubMed Central

Schäffer, Lauge; Brissette, Renee E.; Spetzler, Jane C.; Pillutla, Renuka C.; Østergaard, Søren; Lennick, Michael; Brandt, Jakob; Fletcher, Paul W.; Danielsen, Gillian M.; Hsiao, Ku-Chuan; Andersen, Asser S.; Dedova, Olga; Ribel, Ulla; Hoeg-Jensen, Thomas; Hansen, Per Hertz; Blume, Arthur J.; Markussen, Jan; Goldstein, Neil I.

2003-01-01

Insulin is thought to elicit its effects by crosslinking the two extracellular α-subunits of its receptor, thereby inducing a conformational change in the receptor, which activates the intracellular tyrosine kinase signaling cascade. Previously we identified a series of peptides binding to two discrete hotspots on the insulin receptor. Here we show that covalent linkage of such peptides into homodimers or heterodimers results in insulin agonists or antagonists, depending on how the peptides are linked. An optimized agonist has been shown, both in vitro and in vivo, to have a potency close to that of insulin itself. The ability to construct such peptide derivatives may offer a path for developing agonists or antagonists for treatment of a wide variety of diseases. PMID:12684539

Analysis of palmitoyl apo-astaxanthinals, apo-astaxanthinones, and their epoxides by UHPLC-PDA-ESI-MS.

PubMed

Weesepoel, Yannick; Gruppen, Harry; de Bruijn, Wouter; Vincken, Jean-Paul

2014-10-22

Food products enriched with fatty acid-esterified xanthophylls may result in deviating dietary apo-carotenoids. Therefore, free astaxanthin and its mono- and dipalmitate esters were subjected to two degradation processes in a methanolic model system: light-accelerated autoxidation and hypochlorous acid/hypochlorite (HOCl/OCl(-)) bleaching. Reversed phase ultrahigh-performance liquid chromatography photodiode array with in-line electrospray ionization mass spectrometry (RP-UHPLC-PDA-ESI-MS) was used for assessment of degradation products. Apo-astaxanthinals and -astaxanthinones containing 3 (apo-9) to 10 (apo-8') conjugated double bonds were found upon autoxidation for all three types of astaxanthin (except free apo-8'-astaxanthinal). Fragmentation of [M + H](+) and [M + Na](+) parent masses of apo-astaxanthins from dipalmitate astaxanthin indicated palmitate esterification. Astaxanthin monopalmitate degradation resulted in a mixture of free and palmitate apo-astaxanthins. HOCl/OCl(-) rapidly converted the astaxanthins into a mixture of epoxy-apo-9- and epoxy-apo-13-astaxanthinones. The palmitate ester bond was hardly affected by autoxidation, whereas for HOCl/OCl(-) the ester bond of the apo-astaxanthin palmitoyl esters was degraded.

Influence of metformin on mitochondrial subproteome in the brain of apoE knockout mice.

PubMed

Suski, Maciej; Olszanecki, Rafał; Chmura, Łukasz; Stachowicz, Aneta; Madej, Józef; Okoń, Krzysztof; Adamek, Dariusz; Korbut, Ryszard

2016-02-05

Neurodegenerative diseases are the set of progressive, age-related brain disorders, characterized by an excessive accumulation of mutant proteins in the certain regions of the brain. Such changes, collectively identified as causal factors of neurodegeneration, all impact mitochondria, imminently leading to their dysfunction. These observations predestine mitochondria as an attractive drug target for counteracting degenerative brain damage. The aim of this study was to use a differential proteomic approach to comprehensively assess the changes in mitochondrial protein expression in the brain of apoE-knockout mice (apoE(-/-)) and to investigate the influence of prolonged treatment with metformin - an indirect activator of AMP-activated protein kinase (AMPK) on the brain mitoproteome in apoE(-/-) mice. The quantitative assessment of the brain mitoproteome in apoE(-/-) revealed the changes in 10 proteins expression as compared to healthy C57BL/6J mice and 25 proteins expression in metformin-treated apoE(-/-) mice. Identified proteins mainly included apoptosis regulators, metabolic enzymes and structural proteins. In summary, our study provided proteomic characteristics suggesting the decrease of antioxidant defense and structural disturbances in the brain mitochondria of apoE(-/-) mice as compared to healthy controls. In this setting, the use of metformin changed the expression of several proteins primarily involved in metabolic processes, the regulation of apoptosis and the structural maintenance of mitochondria, what could potentially restore their native functionalities. Copyright © 2015 Elsevier B.V. All rights reserved.

Pharmacological Characterization of 30 Human Melanocortin-4 Receptor Polymorphisms with the Endogenous Proopiomelanocortin Derived Agonists, Synthetic Agonists, and the Endogenous Agouti-Related Protein (AGRP) Antagonist

PubMed Central

Xiang, Zhimin; Proneth, Bettina; Dirain, Marvin L.; Litherland, Sally A.; Haskell-Luevano, Carrie

2010-01-01

The melanocortin-4 receptor (MC4R) is a G-protein coupled receptor (GPCR) that is expressed in the central nervous system and has a role in regulating feeding behavior, obesity, energy homeostasis, male erectile response, and blood pressure. Since the report of the MC4R knockout mouse in 1997, the field has been searching for links between this genetic bio marker and human obesity and type 2 diabetes. More then 80 single nucleotide polymorphisms (SNPs) have been identified from human patients, both obese and non-obese controls. Many significant studies have been performed examining the pharmacological characteristics of these hMC4R SNPs in attempts to identify a molecular defects/insights that might link a genetic factor to the obese phenotype observed in patients possessing these mutations. Our laboratory has previously reported the pharmacological characterization of 40 of these polymorphic hMC4 receptors with multiple endogenous and synthetic ligands. The goal of the current study is to perform a similar comprehensive side-by-side characterization of 30 additional human hMC4R with single nucleotide polymorphisms using multiple endogenous agonists [α-, β, γ2-melanocyte stimulating hormones (MSH) and adrenocorticotropin (ACTH)], the antagonist agouti-related protein hAGRP(87-132), and synthetic agonists [NDP-MSH, MTII, and the tetrapeptide Ac-His-DPhe-Arg-Trp-NH2 (JRH887-9)]. These in vitro data, in some cases, provide a putative molecular link between dysfunctional hMC4R's and human obesity. These 30 hMC4R SNPs include R7H, R18H, R18L, S36Y, P48S, V50M, F51L, E61K, I69T, D90N, S94R, G98R, I121T, A154D, Y157S, W174C, G181D, F202L, A219V, I226T, G231S, G238D, N240S, C271R, S295P, P299L, E308K, I317V, L325F and 750DelGA. All but the N240S hMC4R were identified in obese patients. Additionally, we have characterized a double I102T/V103I hMC4R. In addition to the pharmacological characterization, the hMC4R variants were evaluated for cell surface expression by flow

Gene-Environment Interplay in the Link of Friends&apos; and Nonfriends&apos; Behaviors with Children&apos;s Social Reticence in a Competitive Situation

ERIC Educational Resources Information Center

Guimond, Fanny-Alexandra; Brendgen, Mara; Vitaro, Frank; Forget-Dubois, Nadine; Dionne, Ginette; Tremblay, Richard E.; Boivin, Michel

2014-01-01

This study used a genetically informed design to assess the effects of friends&apos; and nonfriends&apos; reticent and dominant behaviors on children&apos;s observed social reticence in a competitive situation. Potential gene-environment correlations (rGE) and gene-environment interactions (GxE) in the link between (a) friends&apos; and…

LHRH Agonists for the Treatment of Prostate Cancer: 2012

PubMed Central

Lepor, Herbert; Shore, Neal D

2012-01-01

The most recent guidelines on prostate cancer screening from the American Urological Association (2009), the National Comprehensive Cancer Network (2011), and the European Association of Urology (2011), as well as treatment and advances in disease monitoring, have increased the androgen deprivation therapy (ADT) population and the duration of ADT usage as the first-line treatment for metastatic prostate cancer. According to the European Association of Urology, gonadotropin-releasing hormone (GnRH) agonists have become the leading therapeutic option for ADT because they avoid the physical and psychological discomforts associated with orchiectomy. However, GnRH agonists display several shortcomings, including testosterone (T) surge (“clinical flare”) and microsurges. T surge delays the intended serologic endpoint of T suppression and may exacerbate clinical symptoms. Furthermore, ADT manifests an adverse-event spectrum that can impact quality of life with its attendant well-documented morbidities. Strategies to improve ADT tolerability include a holistic management approach, improved diet and exercise, and more specific monitoring to detect and prevent T depletion toxicities. Intermittent ADT, which allows hormonal recovery between treatment periods, has become increasingly utilized as a methodology for improving quality of life while not diminishing chronic ADT efficacy, and may also provide healthcare cost savings. This review assesses the present and potential future role of GnRH agonists in prostate cancer and explores strategies to minimize the adverse-event profile for patients receiving ADT. PMID:23172994

Heritable victimization and the benefits of agonistic relationships

PubMed Central

Lea, Amanda J.; Blumstein, Daniel T.; Wey, Tina W.; Martin, Julien G. A.

2010-01-01

Here, we present estimates of heritability and selection on network traits in a single population, allowing us to address the evolutionary potential of social behavior and the poorly understood link between sociality and fitness. To evolve, sociality must have some heritable basis, yet the heritability of social relationships is largely unknown. Recent advances in both social network analyses and quantitative genetics allow us to quantify attributes of social relationships and estimate their heritability in free-living populations. Our analyses addressed a variety of measures (in-degree, out-degree, attractiveness, expansiveness, embeddedness, and betweenness), and we hypothesized that traits reflecting relationships controlled by an individual (i.e., those that the individual initiated or were directly involved in) would be more heritable than those based largely on the behavior of conspecifics. Identifying patterns of heritability and selection among related traits may provide insight into which types of relationships are important in animal societies. As expected, we found that variation in indirect measures was largely explained by nongenetic variation. Yet, surprisingly, traits capturing initiated interactions do not possess significant additive genetic variation, whereas measures of received interactions are heritable. Measures describing initiated aggression and position in an agonistic network are under selection (0.3 < |S| < 0.4), although advantageous trait values are not inherited by offspring. It appears that agonistic relationships positively influence fitness and seemingly costly or harmful ties may, in fact, be beneficial. Our study highlights the importance of studying agonistic as well as affiliative relationships to understand fully the connections between sociality and fitness. PMID:21115836

Attributional Gender Bias: Teachers&apos; Ability and Effort Explanations for Students&apos; Math Performance

ERIC Educational Resources Information Center

Espinoza, Penelope; Arêas da Luz Fontes, Ana B.; Arms-Chavez, Clarissa J.

2014-01-01

Research is presented on the attributional gender bias: the tendency to generate different attributions (explanations) for female versus male students&apos; performance in math. Whereas boys&apos; successes in math are attributed to ability, girls&apos; successes are attributed to effort; conversely, boys&apos; failures in math are attributed to a…

Treatment of Obesity-Related Complications with Novel Classes of Naturally Occurring PPAR Agonists

PubMed Central

Bassaganya-Riera, Josep; Guri, Amir J.; Hontecillas, Raquel

2011-01-01

The prevalence of obesity and its associated comorbidities has grown to epidemic proportions in the US and worldwide. Thus, developing safe and effective therapeutic approaches against these widespread and debilitating diseases is important and timely. Activation of peroxisome proliferator-activated receptors (PPARs) α, γ, and δ through several classes of pharmaceuticals can prevent or treat a variety of metabolic and inflammatory diseases, including type II diabetes (T2D). Thus, PPARs represent important molecular targets for developing novel and better treatments for a wide range of debilitating and widespread obesity-related diseases and disorders. However, available PPAR γ agonistic drugs such as Avandia have significant adverse side effects, including weight gain, fluid retention, hepatotoxicity, and congestive heart failure. An alternative to synthetic agonists of PPAR γ is the discovery and development of naturally occurring and safer nutraceuticals that may be dual or pan PPAR agonists. The purpose of this paper is to summarize the health effects of three plant-derived PPAR agonists: abscisic acid (ABA), punicic acid (PUA), and catalpic acid (CAA) in the prevention and treatment of chronic inflammatory and metabolic diseases and disorders. PMID:21253508

Treatment of Obesity-Related Complications with Novel Classes of Naturally Occurring PPAR Agonists.

PubMed

Bassaganya-Riera, Josep; Guri, Amir J; Hontecillas, Raquel

2011-01-01

The prevalence of obesity and its associated comorbidities has grown to epidemic proportions in the US and worldwide. Thus, developing safe and effective therapeutic approaches against these widespread and debilitating diseases is important and timely. Activation of peroxisome proliferator-activated receptors (PPARs) α, γ, and δ through several classes of pharmaceuticals can prevent or treat a variety of metabolic and inflammatory diseases, including type II diabetes (T2D). Thus, PPARs represent important molecular targets for developing novel and better treatments for a wide range of debilitating and widespread obesity-related diseases and disorders. However, available PPAR γ agonistic drugs such as Avandia have significant adverse side effects, including weight gain, fluid retention, hepatotoxicity, and congestive heart failure. An alternative to synthetic agonists of PPAR γ is the discovery and development of naturally occurring and safer nutraceuticals that may be dual or pan PPAR agonists. The purpose of this paper is to summarize the health effects of three plant-derived PPAR agonists: abscisic acid (ABA), punicic acid (PUA), and catalpic acid (CAA) in the prevention and treatment of chronic inflammatory and metabolic diseases and disorders.

Modulation Effect of Peroxisome Proliferator-Activated Receptor Agonists on Lipid Droplet Proteins in Liver.

PubMed

Zhu, Yun-Xia; Zhang, Ming-Liang; Zhong, Yuan; Wang, Chen; Jia, Wei-Ping

2016-01-01

Peroxisome proliferator-activated receptor (PPAR) agonists are used for treating hyperglycemia and type 2 diabetes. However, the mechanism of action of these agonists is still under investigation. The lipid droplet-associated proteins FSP27/CIDEC and LSDP5, regulated directly by PPARγ and PPARα, are associated with hepatic steatosis and insulin sensitivity. Here, we evaluated the expression levels of FSP27/CIDEC and LSDP5 and the regulation of these proteins by consumption of a high-fat diet (HFD) or administration of PPAR agonists. Mice with diet-induced obesity were treated with the PPARγ or PPARα agonist, pioglitazone or fenofibrate, respectively. Liver tissues from db/db diabetic mice and human were also collected. Interestingly, FSP27/CIEDC was expressed in mouse and human livers and was upregulated in obese C57BL/6J mice. Fenofibrate treatment decreased hepatic triglyceride (TG) content and FSP27/CIDEC protein expression in mice fed an HFD diet. In mice, LSDP5 was not detected, even in the context of insulin resistance or treatment with PPAR agonists. However, LSDP5 was highly expressed in humans, with elevated expression observed in the fatty liver. We concluded that fenofibrate greatly decreased hepatic TG content and FSP27/CIDEC protein expression in mice fed an HFD, suggesting a potential regulatory role for fenofibrate in the amelioration of hepatic steatosis.

New-generation 5-HT4 receptor agonists: potential for treatment of gastrointestinal motility disorders.

PubMed

Manabe, Noriaki; Wong, Banny S; Camilleri, Michael

2010-06-01

Gastrointestinal (GI) dysmotility is an important mechanism in functional GI disorders (FGIDs) including constipation, irritable bowel syndrome, functional dyspepsia, and gastroparesis. 5-hydroxytryptamine(4) (5-HT(4)) receptors are targets for the treatment of GI motility disorders. However, older 5-HT(4) receptor agonists had limited clinical success because they were associated with changes in the function of the cardiac HERG potassium channel. We conducted a PubMed search using the following key words alone or in combination: 5-HT(4), safety, toxicity, pharmacokinetics, pharmacodynamics, clinical trial, cardiac, hERG, arrhythmia, potassium current, elderly, prucalopride, ATI-7505, and velusetrag (TD-5108), to review mechanisms of action, clinical efficacy, safety and tolerability of three new-generation 5-HT(4) receptor agonists. Prucalopride, ATI-7505, and velusetrag (TD-5108) are highly selective, high-affinity 5-HT(4) receptor agonists that are devoid of action on other receptors within their therapeutic range. Their efficacy has been demonstrated in pharmacodynamic studies which demonstrate acceleration of colonic transit and, to a variable degree, in clinical trials that significantly relieve chronic constipation. Currently available evidence shows that the new 5-HT(4) receptor agonists have safe cardiac profiles. New-generation 5-HT(4) receptor agonists and future drugs targeting organ-specific splice variants are promising approaches to treat GI dysmotility, particularly colonic diseases.

Antinociceptive action of NOP and opioid receptor agonists in the mouse orofacial formalin test.

PubMed

Rizzi, A; Ruzza, C; Bianco, S; Trapella, C; Calo', G

2017-08-01

Nociceptin/orphanin FQ (N/OFQ) modulates several biological functions, including pain transmission via selective activation of a specific receptor named NOP. The aim of this study was the investigation of the antinociceptive properties of NOP agonists and their interaction with opioids in the trigeminal territory. The orofacial formalin (OFF) test in mice was used to investigate the antinociceptive potential associated to the activation of NOP and opioid receptors. Mice subjected to OFF test displayed the typical biphasic nociceptive response and sensitivity to opioid and NSAID drugs. Mice knockout for the NOP gene displayed a robust pronociceptive phenotype. The NOP selective agonist Ro 65-6570 (0.1-1mgkg -1 ) and morphine (0.1-10mgkg -1 ) elicited dose dependent antinociceptive effects in the OFF with the alkaloid showing larger effects; the isobologram analysis of their actions demonstrated an additive type of interaction. The mixed NOP/opioid receptor agonist cebranopadol elicited potent (0.01-0.1mgkg -1 ) and robust antinociceptive effects. In the investigated dose range, all drugs did not modify the motor performance of the mice in the rotarod test. Collectively the results of this study demonstrated that selective NOP agonists and particularly mixed NOP/opioid agonists are worthy of development as innovative drugs to treat painful conditions of the trigeminal territory. Copyright © 2017 Elsevier Inc. All rights reserved.

5-Functionalized indazoles as glucocorticoid receptor agonists.

PubMed

Bai, Mei; Carr, Grant; Deorazio, Russell J; Friedrich, Thomas D; Dobritsa, Svetlana; Fitzpatrick, Kevin; Guzzo, Peter R; Kitchen, Douglas B; Lynch, Michael A; Peace, Denise; Sajad, Mohammed; Usyatinsky, Alexander; Wolf, Mark A

2010-05-15

An indazole based series of glucocorticoid receptor agonists is reported. The SAR exploration of this scaffold yielded compounds with nanomolar affinity for the glucocorticoid receptor with indications of selectivity for the preferred transrepression mechanism; in vivo efficacy was observed in the mouse LPS induced TNFalpha model for compound 28. Copyright 2010 Elsevier Ltd. All rights reserved.

Development of novel neurokinin 3 receptor (NK3R) selective agonists with resistance to proteolytic degradation.

PubMed

Misu, Ryosuke; Oishi, Shinya; Yamada, Ai; Yamamura, Takashi; Matsuda, Fuko; Yamamoto, Koki; Noguchi, Taro; Ohno, Hiroaki; Okamura, Hiroaki; Ohkura, Satoshi; Fujii, Nobutaka

2014-10-23

Neurokinin B (NKB) regulates the release of gonadotropin-releasing hormone (GnRH) via activation of the neurokinin-3 receptor (NK3R). We evaluated the biological stability of NK3R selective agonists to develop novel NK3R agonists to regulate reproductive functions. On the basis of degradation profiles, several peptidomimetic derivatives were designed. The modification of senktide with (E)-alkene dipeptide isostere generated a novel potent NK3R agonist with high stability and prolonged bioactivity.

Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Cureri, Peter A. (Technical Monitor)

2002-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of cAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of cAMP by either epinephrine or isoproterenol.

PPAR-γ Agonists As Antineoplastic Agents in Cancers with Dysregulated IGF Axis

PubMed Central

Vella, Veronica; Nicolosi, Maria Luisa; Giuliano, Stefania; Bellomo, Maria; Belfiore, Antonino; Malaguarnera, Roberta

2017-01-01

It is now widely accepted that insulin resistance and compensatory hyperinsulinemia are associated to increased cancer incidence and mortality. Moreover, cancer development and progression as well as cancer resistance to traditional anticancer therapies are often linked to a deregulation/overactivation of the insulin-like growth factor (IGF) axis, which involves the autocrine/paracrine production of IGFs (IGF-I and IGF-II) and overexpression of their cognate receptors [IGF-I receptor, IGF-insulin receptor (IR), and IR]. Recently, new drugs targeting various IGF axis components have been developed. However, these drugs have several limitations including the occurrence of insulin resistance and compensatory hyperinsulinemia, which, in turn, may affect cancer cell growth and survival. Therefore, new therapeutic approaches are needed. In this regard, the pleiotropic effects of peroxisome proliferator activated receptor (PPAR)-γ agonists may have promising applications in cancer prevention and therapy. Indeed, activation of PPAR-γ by thiazolidinediones (TZDs) or other agonists may inhibit cell growth and proliferation by lowering circulating insulin and affecting key pathways of the Insulin/IGF axis, such as PI3K/mTOR, MAPK, and GSK3-β/Wnt/β-catenin cascades, which regulate cancer cell survival, cell reprogramming, and differentiation. In light of these evidences, TZDs and other PPAR-γ agonists may be exploited as potential preventive and therapeutic agents in tumors addicted to the activation of IGF axis or occurring in hyperinsulinemic patients. Unfortunately, clinical trials using PPAR-γ agonists as antineoplastic agents have reached conflicting results, possibly because they have not selected tumors with overactivated insulin/IGF-I axis or occurring in hyperinsulinemic patients. In conclusion, the use of PPAR-γ agonists in combined therapies of IGF-driven malignancies looks promising but requires future developments. PMID:28275367

Local administration of a hedgehog agonist accelerates fracture healing in a mouse model

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

Kashiwagi, Miki; Division of Clinical Biotechnology, The University of Tokyo Graduate School of Medicine, Bunkyo-ku, Tokyo, 113-0033; Hojo, Hironori

Bone fracture healing is processed through multiple biological stages including the transition from cartilaginous callus to bony callus formation. Because of its specific, temporal and indispensable functions demonstrated by mouse genetic studies, Hedgehog (Hh) signaling is one of the most potent signaling pathways involved in these processes, but the effect of Hh-signaling activation by small compounds on the repair process had not yet been addressed. Here we examined therapeutic effects of local and one shot-administration of the Hh agonist known as smoothened agonist (SAG) on bone fracture healing in a mouse model. A quantitative analysis with three-dimensional micro-computed tomography showedmore » that SAG administration increased the size of both the cartilaginous callus and bony callus at 14 days after the surgery. A histological analysis showed that SAG administration increased the number of cells expressing a proliferation marker and a chondrocyte marker in cartilaginous callus as well as the cells expressing an osteoblast marker in bony callus. These results indicate that the SAG administration resulted in an enhancement of callus formation during bone fracture healing, which is at least in part mediated by an increase in chondrocyte proliferation in cartilaginous callus and the promotion of bone formation in bony callus. Therapeutic strategies with a SAG-mediated protocol may thus be useful for the treatment of bone fractures. - Highlights: • Local administration of a Hh agonist accelerates callus formation. • The Hh agonist administration promotes chondrocyte proliferation in the soft callus. • The Hh agonist administration increases osteoblast formation in the hard callus.« less

Comparison of the release of microRNAs and extracellular vesicles from platelets in response to different agonists.

PubMed

Ambrose, Ashley R; Alsahli, Mohammed A; Kurmani, Sameer A; Goodall, Alison H

2018-07-01

On activation platelets release microRNAs and extracellular vesicles (EV) into circulation. The release of EV from platelets has been shown to be dependent on the agonist; in this study, we investigated whether the microRNA profile or EV released from platelets was also agonist specific. Washed platelets from healthy subjects were maximally stimulated with agonists specific for the receptors for collagen (Glycoprotein VI (GPVI)), thrombin (PAR1/PAR4), or ADP (P2Y1/P2Y12) with/without inhibiting secondary mediators, using aspirin to block cyclooxygenase-1 and apyrase to remove ADP. The released microRNAs were profiled using TaqMan microRNA microarray cards. Platelet-derived EV (pdEV) were characterized by size (Nanoparticle Tracking Analysis, NTA), for procoagulant activity (Annexin-V binding and support of thrombin generation), and for the EV markers CD63 and HSP70. Platelet activation triggered the release of 57-79 different microRNAs, dependent upon agonist, with a core of 46 microRNAs observed with all agonists. There was a high level of correlation between agonists (r 2  > 0.98; p < 0.0001 for all), and with the microRNA content of the parent platelets (r 2  > 0.98; p < 0.0001). The 46 microRNAs seen in all samples are predicted to have significant effects on the translation of proteins involved in endocytosis, cell cycle control, and differentiation. MiR-223-3p was the most abundant in all samples and has previously been implicated in myeloid lineage development and demonstrated to have anti-inflammatory effects. Stimulation through GPVI produced a pdEV population with significantly more procoagulant activity than the other agonists. Apyrase significantly reduced microRNA and pdEV release, while aspirin had little effect. These data suggest that all tested agonists trigger the release of a similar microRNA profile while the procoagulant activity of the pdEV was agonist dependent. ADP was shown to play an important role in the release of both micro

ApoE and the role of very low density lipoproteins in adipose tissue inflammation

USDA-ARS?s Scientific Manuscript database

Our goal was too identify the role of triglyceride-rich lipoproteins and apoE, a major apolipoprotein in triglyceride-rich lipoproteins, in adipose tissue inflammation with high-fat diet induced obesity. Male apoE-/- and C57BL/6J wild-type mice fed high fat diets for 12 weeks were assessed for metab...

Beta agonists in livestock feed: status, health concerns, and international trade.

PubMed

Centner, T J; Alvey, J C; Stelzleni, A M

2014-09-01

Since the U.S. Food and Drug Administration approved ractopamine hydrochloride and zilpaterol hydrochloride in animal feeds, usage of those compounds has been a topic of worldwide debate. Ractopamine and zilpaterol are β-adrenergic agonists used as veterinary drugs to increase weight gain in certain animals raised for food. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established maximum residue limits for ractopamine, which were adopted by the Codex Alimentarius Commission (Codex). No maximum residue limits for zilpaterol have been adopted by JECFA, and new reports of animal mobility issues confront the use of this feed additive. However, many countries disagree with the Codex standards and are restricting or banning meat products containing β agonists. The bans by major importers of U.S. meat products have prompted some to advocate that the United States use the World Trade Organization dispute settlement body. This paper looks at the developments to provide a fuller accounting of what the issues may mean to U.S. firms selling meat products containing residues of β agonists.

Differential epileptogenic potentials of selective mu and delta opiate receptor agonists.

PubMed

Haffmans, J; Dzoljic, M R

1983-01-01

By using electroencephalographic (EEG) and electromyographic recordings in anaesthetized and free-moving rats, two opioid peptides, known as selective agonists for mu and delta opiate receptors, respectively, were examined for their epileptogenic properties. The delta receptor peptide (DSTLE, 4.6-18.6 nmol, intraventricularly, ivt), a putative delta opiate agonist, produced a dose-related increase of myoclonic contractions (MC) with epileptic discharges in anaesthetized rats and severe wet dog shakes, with occasionally falling down, in free-moving animals. Morphiceptin, a specific mu opiate agonist, used in equimolar doses and under the same experimental conditions, had a significantly less pronounced effect on the number of MC and epileptiform EEG phenomena. Similarly, DSTLE (18.6 nmol) injected in the CA2 area of the hippocampus, a region with a nearly equal distribution of mu and delta opiate receptors, induced epileptic discharges in anaesthetized and free-moving rats, while an equimolar dose of morphiceptin had no significant effect. It is suggested that the epileptiform activity of opioid peptides is mainly due to an activation of delta opiate receptors in the central nervous system.

Biphasic Effect of Melanocortin Agonists on Metabolic Rate and Body Temperature

PubMed Central

Lute, Beth; Jou, William; Lateef, Dalya M.; Goldgof, Margalit; Xiao, Cuiying; Piñol, Ramón A.; Kravitz, Alexxai V.; Miller, Nicole R.; Huang, Yuning George; Girardet, Clemence; Butler, Andrew A.; Gavrilova, Oksana; Reitman, Marc L.

2014-01-01

Summary The melanocortin system regulates metabolic homeostasis and inflammation. Melanocortin agonists have contradictorily been reported to both increase and decrease metabolic rate and body temperature. We find two distinct physiologic responses occurring at similar doses. Intraperitoneal administration of the nonselective melanocortin agonist MTII causes a melanocortin-4 receptor (Mc4r) mediated hypermetabolism/hyperthermia. This is preceded by a profound, transient hypometabolism/hypothermia that is preserved in mice lacking any one of Mc1r, Mc3r, Mc4r, or Mc5r. Three other melanocortin agonists also caused hypothermia, which is actively achieved via seeking a cool environment, vasodilation, and inhibition of brown adipose tissue thermogenesis. These results suggest that the hypometabolic/hypothermic effect of MTII is not due to a failure of thermoregulation. The hypometabolism/hypothermia was prevented by dopamine antagonists and MTII selectively activated arcuate nucleus dopaminergic neurons; these neurons may contribute to the hypometabolism/hypothermia. We propose that the hypometabolism/hypothermia is a regulated response, potentially beneficial during extreme physiologic stress. PMID:24981835

Stimulants as specific inducers of dopamine-independent σ agonist self-administration in rats.

PubMed

Hiranita, Takato; Soto, Paul L; Tanda, Gianluigi; Kopajtic, Theresa A; Katz, Jonathan L

2013-10-01

A previous study showed that cocaine self-administration induced dopamine-independent reinforcing effects of σ agonists mediated by their selective actions at σ1 receptors (σ1Rs), which are intracellularly mobile chaperone proteins implicated in abuse-related effects of stimulants. The present study assessed whether the induction was specific to self-administration of cocaine. Rats were trained to self-administer the dopamine releaser, d-methamphetamine (0.01-0.32 mg/kg per injection), the μ-opioid receptor agonist, heroin (0.001-0.032 mg/kg per injection), and the noncompetitive N-methyl-d-aspartate receptor/channel antagonist ketamine (0.032-1.0 mg/kg per injection). As with cocaine, self-administration of d-methamphetamine induced reinforcing effects of the selective σ1R agonists PRE-084 [2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate hydrochloride] and (+)-pentazocine (0.032-1.0 mg/kg per injection, each). In contrast, neither self-administration of heroin nor ketamine induced PRE-084 or (+)-pentazocine (0.032-10 mg/kg per injection, each) self-administration. Although the σ1R agonists did not maintain responding in subjects with histories of heroin or ketamine self-administration, substitution for those drugs was obtained with appropriate agonists (e.g., remifentanil, 0.1-3.2 µg/kg per injection, for heroin and (5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ((+)-MK 801; dizocilpine), 0.32-10.0 µg/kg per injection, for ketamine). The σR antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine dihydrobromide (BD 1008; 1.0-10 mg/kg) dose-dependently blocked PRE-084 self-administration but was inactive against d-methamphetamine, heroin, and ketamine. In contrast, PRE-084 self-administration was affected neither by the dopamine receptor antagonist (+)-butaclamol (10-100 μg/kg) nor by the opioid antagonist (-)-naltrexone (1.0-10 mg/kg), whereas these antagonists were active against d

Stimulants as Specific Inducers of Dopamine-Independent σ Agonist Self-Administration in Rats

PubMed Central

Hiranita, Takato; Soto, Paul L.; Tanda, Gianluigi; Kopajtic, Theresa A.

2013-01-01

A previous study showed that cocaine self-administration induced dopamine-independent reinforcing effects of σ agonists mediated by their selective actions at σ1 receptors (σ1Rs), which are intracellularly mobile chaperone proteins implicated in abuse-related effects of stimulants. The present study assessed whether the induction was specific to self-administration of cocaine. Rats were trained to self-administer the dopamine releaser, d-methamphetamine (0.01–0.32 mg/kg per injection), the μ-opioid receptor agonist, heroin (0.001–0.032 mg/kg per injection), and the noncompetitive N-methyl-d-aspartate receptor/channel antagonist ketamine (0.032–1.0 mg/kg per injection). As with cocaine, self-administration of d-methamphetamine induced reinforcing effects of the selective σ1R agonists PRE-084 [2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate hydrochloride] and (+)-pentazocine (0.032–1.0 mg/kg per injection, each). In contrast, neither self-administration of heroin nor ketamine induced PRE-084 or (+)-pentazocine (0.032–10 mg/kg per injection, each) self-administration. Although the σ1R agonists did not maintain responding in subjects with histories of heroin or ketamine self-administration, substitution for those drugs was obtained with appropriate agonists (e.g., remifentanil, 0.1–3.2 µg/kg per injection, for heroin and (5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ((+)-MK 801; dizocilpine), 0.32–10.0 µg/kg per injection, for ketamine). The σR antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine dihydrobromide (BD 1008; 1.0–10 mg/kg) dose-dependently blocked PRE-084 self-administration but was inactive against d-methamphetamine, heroin, and ketamine. In contrast, PRE-084 self-administration was affected neither by the dopamine receptor antagonist (+)-butaclamol (10–100 μg/kg) nor by the opioid antagonist (−)-naltrexone (1.0–10 mg/kg), whereas these antagonists were active

A Small Molecule Inverse Agonist for the Human Thyroid-Stimulating Hormone Receptor

PubMed Central

Neumann, Susanne; Huang, Wenwei; Eliseeva, Elena; Titus, Steve; Thomas, Craig J.; Gershengorn, Marvin C.

2010-01-01

Small molecule inverse agonists for the TSH receptor (TSHR) may be used as probes of the role of basal (or agonist-independent or constitutive) signaling and may have therapeutic potential as orally active drugs to inhibit basal signaling in patients with thyroid cancer and in some patients with hyperthyroidism. We describe the first small-molecule ligand [1;2-(3-((2,6-dimethylphenoxy)methyl)-4-methoxyphenyl)-3-(furan-2-ylmethyl)-2,3-dihydroquinazolin-4(1H)-one] that exhibits inverse agonist properties at TSHR. 1 inhibits basal and TSH-stimulated signaling, measured as cAMP production, by TSHRs in HEK-EM 293 cells stably expressing wild-type TSHRs; the antagonism of TSH-mediated signaling is competitive. 1 also inhibits basal signaling by wild-type TSHRs, and four constitutively active mutants of TSHR expressed transiently in HEK-EM 293 cells. 1 was active under more physiologically relevant conditions in primary cultures of human thyrocytes expressing endogenous TSHRs where it inhibited basal levels of mRNA transcripts for thyroglobulin, thyroperoxidase, sodium iodide symporter, and TSHR. These data serve as proof of principle that small, drug-like molecules can inhibit basal signaling by TSHR. We suggest that this small molecule is a lead compound for the development of higher-potency inverse agonists that can be used as probes of TSHR biology with therapeutic potential. PMID:20427476

Comparative Review of Approved Melatonin Agonists for the Treatment of Circadian Rhythm Sleep-Wake Disorders.

PubMed

Williams, Wilbur P Trey; McLin, Dewey E; Dressman, Marlene A; Neubauer, David N

2016-09-01

Circadian rhythm sleep-wake disorders (CRSWDs) are characterized by persistent or recurrent patterns of sleep disturbance related primarily to alterations of the circadian rhythm system or the misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep. These disorders collectively represent a significant unmet medical need, with a total prevalence in the millions, a substantial negative impact on quality of life, and a lack of studied treatments for most of these disorders. Activation of the endogenous melatonin receptors appears to play an important role in setting the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Therefore, melatonin agonists, which may be able to shift and/or stabilize the circadian phase, have been identified as potential therapeutic candidates for the treatment of CRSWDs. Currently, only one melatonin receptor agonist, tasimelteon, is approved for the treatment of a CRSWD: non-24-hour sleep-wake disorder (or non-24). However, three additional commercially available melatonin receptor agonists-agomelatine, prolonged-release melatonin, and ramelteon-have been investigated for potential use for treatment of CRSWDs. Data indicate that these melatonin receptor agonists have distinct pharmacologic profiles that may help clarify their clinical use in CRSWDs. We review the pharmacokinetic and pharmacodynamic properties of these melatonin agonists and summarize their efficacy profiles when used for the treatment of CRSWDs. Further studies are needed to determine the therapeutic potential of these melatonin agonists for most CRSWDs. © 2016 Vanda Pharmaceuticals, Inc. Pharmacotherapy published by Wiley Periodicals, Inc. on behalf of Pharmacotherapy Publications, Inc.

Conformationally constrained farnesoid X receptor (FXR) agonists: Naphthoic acid-based analogs of GW 4064.

PubMed

Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Jones, Stacey A; Kaldor, Istvan; Liu, Yaping; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Navas, Frank; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Wisely, G Bruce

2008-08-01

Starting from the known FXR agonist GW 4064 1a, a series of stilbene replacements were prepared. The 6-substituted 1-naphthoic acid 1b was an equipotent FXR agonist with improved developability parameters relative to 1a. Analog 1b also reduced the severity of cholestasis in the ANIT acute cholestatic rat model.

Middle-aged human apoE4 targeted-replacement mice show retention deficits on a wide range of spatial memory tasks.

PubMed

Bour, Alexandra; Grootendorst, Jeannette; Vogel, Elise; Kelche, Christian; Dodart, Jean-Cosme; Bales, Kelly; Moreau, Pierre-Henri; Sullivan, Patrick M; Mathis, Chantal

2008-11-21

Apolipoprotein (apo) E4, one of three human apoE (h-apoE) isoforms, has been identified as a major genetic risk factor for Alzheimer's disease and for cognitive deficits associated with aging. However, the biological mechanisms involving apoE in learning and memory processes are unclear. A potential isoform-dependent role of apoE in cognitive processes was studied in human apoE targeted-replacement (TR) mice. These mice express either the human apoE3 or apoE4 gene under the control of endogenous murine apoE regulatory sequences, resulting in physiological expression of h-apoE in both a temporal and spatial pattern similar to humans. Male and female apoE3-TR, apoE4-TR, apoE-knockout and C57BL/6J mice (15-18 months) were tested with spatial memory and avoidance conditioning tasks. Compared to apoE3-TR mice, spatial memory in female apoE4-TR mice was impaired based on their poor performances in; (i) the probe test of the water-maze reference memory task, (ii) the water-maze working memory task and (iii) an active avoidance Y-maze task. Retention performance on a passive avoidance task was also impaired in apoE4-TR mice, but not in other genotypes. These deficits in both spatial and avoidance memory tasks may be related to the anatomical and functional abnormalities previously reported in the hippocampus and the amygdala of apoE4-TR mice. We conclude that the apoE4-TR mice provide an excellent model for understanding the mechanisms underlying apoE4-dependent susceptibility to cognitive decline.

Differential activation of G-proteins by mu-opioid receptor agonists.

PubMed

Saidak, Zuzana; Blake-Palmer, Katherine; Hay, Debbie L; Northup, John K; Glass, Michelle

2006-03-01

We investigated the ability of the activated mu-opioid receptor (MOR) to differentiate between myristoylated G(alphai1) and G(alphaoA) type G(alpha) proteins, and the maximal activity of a range of synthetic and endogenous agonists to activate each G(alpha) protein. Membranes from HEK293 cells stably expressing transfected MOR were chaotrope extracted to denature endogenous G-proteins and reconstituted with specific purified G-proteins. The G(alpha) subunits were generated in bacteria and were demonstrated to be recognised equivalently to bovine brain purified G(alpha) protein by CB(1) cannabinoid receptors. The ability of agonists to catalyse the MOR-dependent GDP/[(35)S]GTP(gamma)S exchange was then compared for G(alphai1) and G(alphaoA). Activation of MOR by DAMGO produced a high-affinity saturable interaction for G(alphaoA) (K(m)=20+/-1 nM) but a low-affinity interaction with G(alphai1) (K(m)=116+/-12 nM). DAMGO, met-enkephalin and leucine-enkephalin displayed maximal G(alpha) activation among the agonists evaluated. Endomorphins 1 and 2, methadone and beta-endorphin activated both G(alpha) to more than 75% of the maximal response, whereas fentanyl partially activated both G-proteins. Buprenorphine and morphine demonstrated a statistically significant difference between the maximal activities between G(alphai1) and G(alphaoA). Interestingly, DAMGO, morphine, endomorphins 1 and 2, displayed significant differences in the potencies for the activation of the two G(alpha). Differences in maximal activity and potency, for G(alphai1) versus G(alphaoA), are both indicative of agonist selective activation of G-proteins in response to MOR activation. These findings may provide a starting point for the design of drugs that demonstrate greater selectivity between these two G-proteins and therefore produce a more limited range of effects.

Differential activation of G-proteins by μ-opioid receptor agonists

PubMed Central

Saidak, Zuzana; Blake-Palmer, Katherine; Hay, Debbie L; Northup, John K; Glass, Michelle

2006-01-01

We investigated the ability of the activated μ-opioid receptor (MOR) to differentiate between myristoylated Gαi1 and GαoA type Gα proteins, and the maximal activity of a range of synthetic and endogenous agonists to activate each Gα protein. Membranes from HEK293 cells stably expressing transfected MOR were chaotrope extracted to denature endogenous G-proteins and reconstituted with specific purified G-proteins. The Gα subunits were generated in bacteria and were demonstrated to be recognised equivalently to bovine brain purified Gα protein by CB1 cannabinoid receptors. The ability of agonists to catalyse the MOR-dependent GDP/[35S]GTPγS exchange was then compared for Gαi1 and GαoA. Activation of MOR by DAMGO produced a high-affinity saturable interaction for GαoA (Km=20±1 nM) but a low-affinity interaction with Gαi1 (Km=116±12 nM). DAMGO, met-enkephalin and leucine-enkephalin displayed maximal Gα activation among the agonists evaluated. Endomorphins 1 and 2, methadone and β-endorphin activated both Gα to more than 75% of the maximal response, whereas fentanyl partially activated both G-proteins. Buprenorphine and morphine demonstrated a statistically significant difference between the maximal activities between Gαi1 and GαoA. Interestingly, DAMGO, morphine, endomorphins 1 and 2, displayed significant differences in the potencies for the activation of the two Gα. Differences in maximal activity and potency, for Gαi1 versus GαoA, are both indicative of agonist selective activation of G-proteins in response to MOR activation. These findings may provide a starting point for the design of drugs that demonstrate greater selectivity between these two G-proteins and therefore produce a more limited range of effects. PMID:16415903

On the Relations between Parents&apos; Ideals and Children&apos;s Autonomy

ERIC Educational Resources Information Center

de Ruyter, Doret J.; Schinkel, Anders

2013-01-01

In this article Doret J. de Ruyter and Anders Schinkel argue that parents&apos; ideals can enhance children&apos;s autonomy, but that they may also have a detrimental effect on the development of children&apos;s autonomy. After describing the concept of "ideals" and elucidating a systems theoretical conception of autonomy, de Ruyter and…

Characterization of 12 GnRH peptide agonists – a kinetic perspective

PubMed Central

Nederpelt, Indira; Georgi, Victoria; Schiele, Felix; Nowak‐Reppel, Katrin; Fernández‐Montalván, Amaury E.; IJzerman, Adriaan P.

2015-01-01

Background and Purpose Drug‐target residence time is an important, yet often overlooked, parameter in drug discovery. Multiple studies have proposed an increased residence time to be beneficial for improved drug efficacy and/or longer duration of action. Currently, there are many drugs on the market targeting the gonadotropin‐releasing hormone (GnRH) receptor for the treatment of hormone‐dependent diseases. Surprisingly, the kinetic receptor‐binding parameters of these analogues have not yet been reported. Therefore, this project focused on determining the receptor‐binding kinetics of 12 GnRH peptide agonists, including many marketed drugs. Experimental Approach A novel radioligand‐binding competition association assay was developed and optimized for the human GnRH receptor with the use of a radiolabelled peptide agonist, [125I]‐triptorelin. In addition to radioligand‐binding studies, a homogeneous time‐resolved FRET Tag‐lite™ method was developed as an alternative assay for the same purpose. Key Results Two novel competition association assays were successfully developed and applied to determine the kinetic receptor‐binding characteristics of 12 high‐affinity GnRH peptide agonists. Results obtained from both methods were highly correlated. Interestingly, the binding kinetics of the peptide agonists were more divergent than their affinities with residence times ranging from 5.6 min (goserelin) to 125 min (deslorelin). Conclusions and Implications Our research provides new insights by incorporating kinetic, next to equilibrium, binding parameters in current research and development that can potentially improve future drug discovery targeting the GnRH receptor. PMID:26398856

Targeting alpha-7 nicotinic neurotransmission in schizophrenia: A novel agonist strategy

PubMed Central

Deutsch, Stephen I.; Schwartz, Barbara L.; Schooler, Nina R.; Brown, Clayton H.; Rosse, Richard B.; Rosse, Stephanie M.

2013-01-01

Alpha7 nicotinic acetylcholine receptor (α7 nAChR) agonists may be valuable treatments for negative symptoms and cognitive impairment in schizophrenia. Unfortunately, chronic exposure to an agonist may reduce the receptor’s sensitivity. Therefore, we combined CDP-choline, a dietary source of the direct agonist choline, with galantamine, a positive allosteric modulator (PAM) of nicotinic acetylcholine receptors, to improve the efficiency of transducing the choline signal and, possibly, preserve the receptor in a sensitive state. We conducted a single-site, double-blind randomized clinical trial comparing galantamine/CDP-choline to placebos in schizophrenia patients with negative symptoms who were receiving second generation antipsychotics. Forty-three subjects received galantamine and CDP-choline or matching placebos for 16 weeks. The primary outcome measure was the 5-item Marder negative-symptoms factor of the Positive and Negative Syndrome Scale (PANSS). Cognition and functioning were also assessed. Trial completion was high; 79%. There was no significant treatment effect on negative symptoms, other PANSS symptom factors, or the MATRICS Cognitive Consensus Battery. There were significant treatment effects in overall functioning and a test of free verbal recall. Three subjects discontinued treatment in the active treatment group for gastro-intestinal adverse events (AE). The most common AE for galantamine/CDP-choline was abdominal pain; for placebo it was headache and sweating. Although there was no significant treatment effect on negative symptoms, the direction of effect mirrored the effects on a cognitive measure and overall functioning. Further study of α7 nAChR agonist/PAMs are warranted in larger studies that will have greater power. PMID:23768813

The Case for the Use of PPARγ Agonists as an Adjunctive Therapy for Cerebral Malaria

PubMed Central

Serghides, Lena

2012-01-01

Cerebral malaria is a severe complication of Plasmodium falciparum infection associated with high mortality even when highly effective antiparasitic therapy is used. Adjunctive therapies that modify the pathophysiological processes caused by malaria are a possible way to improve outcome. This review focuses on the utility of PPARγ agonists as an adjunctive therapy for the treatment of cerebral malaria. The current knowledge of PPARγ agonist use in malaria is summarized. Findings from experimental CNS injury and disease models that demonstrate the potential for PPARγ agonists as an adjunctive therapy for cerebral malaria are also discussed. PMID:21772838

Small-molecule agonists for the thyrotropin receptor stimulate thyroid function in human thyrocytes and mice

PubMed Central

Neumann, Susanne; Huang, Wenwei; Titus, Steve; Krause, Gerd; Kleinau, Gunnar; Alberobello, Anna Teresa; Zheng, Wei; Southall, Noel T.; Inglese, James; Austin, Christopher P.; Celi, Francesco S.; Gavrilova, Oksana; Thomas, Craig J.; Raaka, Bruce M.; Gershengorn, Marvin C.

2009-01-01

Seven-transmembrane-spanning receptors (7TMRs) are prominent drug targets. However, small-molecule ligands for 7-transmembrane-spanning receptors for which the natural ligands are large, heterodimeric glycoprotein hormones, like thyroid-stimulating hormone (TSH; thyrotropin), have only recently been reported, and none are approved for human use. We have used quantitative high-throughput screening to identify a small-molecule TSH receptor (TSHR) agonist that was modified to produce a second agonist with increased potency. We show that these agonists are highly selective for human TSHR versus other glycoprotein hormone receptors and interact with the receptor's serpentine domain. A binding pocket within the transmembrane domain was defined by docking into a TSHR homology model and was supported by site-directed mutagenesis. In primary cultures of human thyrocytes, both TSH and the agonists increase mRNA levels for thyroglobulin, thyroperoxidase, sodium iodide symporter, and deiodinase type 2, and deiodinase type 2 enzyme activity. Moreover, oral administration of the agonist stimulated thyroid function in mice, resulting in increased serum thyroxine and thyroidal radioiodide uptake. Thus, we discovered a small molecule that activates human TSHR in vitro, is orally active in mice, and could be a lead for development of drugs to use in place of recombinant human TSH in patients with thyroid cancer. PMID:19592511

Discovery of N-(4-aryl-5-aryloxy-thiazol-2-yl)-amides as potent RORγt inverse agonists.

PubMed

Wang, Yonghui; Yang, Ting; Liu, Qian; Ma, Yingli; Yang, Liuqing; Zhou, Ling; Xiang, Zhijun; Cheng, Ziqiang; Lu, Sijie; Orband-Miller, Lisa A; Zhang, Wei; Wu, Qianqian; Zhang, Kathleen; Li, Yi; Xiang, Jia-Ning; Elliott, John D; Leung, Stewart; Ren, Feng; Lin, Xichen

2015-09-01

A novel series of N-(4-aryl-5-aryloxy-thiazol-2-yl)-amides as RORγt inverse agonists was discovered. Binding mode analysis of a RORγt partial agonist (2c) revealed by co-crystal structure in RORγt LBD suggests that the inverse agonists do not directly interfere with the interaction between H12 and the RORγt LBD. Detailed SAR exploration led to identification of potent RORγt inverse agonists such as 3m with a pIC50 of 8.0. Selected compounds in the series showed reasonable activity in Th17 cell differentiation assay as well as low intrinsic clearance in mouse liver microsomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Anatomical Basis for Opponent Process Mechanisms of Opiate Withdrawal

PubMed Central

Radke, Anna K.; Rothwell, Patrick E.; Gewirtz, Jonathan C.

2011-01-01

Opponent process theory predicts that the first step in the induction of drug withdrawal is the activation of reward-related circuitry. Using the acoustic startle reflex as a model of anxiety-like behavior in rats, we show the emergence of a negative affective state during withdrawal after direct infusion of morphine into the ventral tegmental area (VTA), the origin of the mesolimbic dopamine system. Potentiation of startle during withdrawal from systemic morphine exposure requires a decrease in opiate receptor stimulation in the VTA and can be relieved by administration of the dopamine receptor agonist apomorphine. Together, our results suggest that the emergence of anxiety during withdrawal from acute opiate exposure begins with activation of VTA mesolimbic dopamine circuitry, providing a mechanism for the opponent process view of withdrawal. PMID:21593338

Agonist Met antibodies define the signalling threshold required for a full mitogenic and invasive program of Kaposi's Sarcoma cells.

PubMed

Bardelli, Claudio; Sala, Marilena; Cavallazzi, Umberto; Prat, Maria

2005-09-09

We previously showed that the Kaposi Sarcoma line KS-IMM express a functional Met tyrosine kinase receptor, which, upon HGF stimulation, activates motogenic, proliferative, and invasive responses. In this study, we investigated the signalling pathways activated by HGF, as well as by Met monoclonal antibodies (Mabs), acting as full or partial agonists. The full agonist Mab mimics HGF in all biological and biochemical aspects. It elicits the whole spectrum of responses, while the partial agonist Mab induces only wound healing. These differences correlated with a more prolonged and sustained tyrosine phosphorylation of the receptor and MAPK evoked by HGF and by the full agonist Mab, relative to the partial agonist Mab. Since Gab1, JNK and PI 3-kinase are activated with same intensity and kinetics by HGF and by the two agonist antibodies, it is concluded that level and duration of MAPK activation by Met receptor are crucial for the induction of a full HGF-dependent mitogenic and invasive program in KS cells.

ICI 204448: a kappa-opioid agonist with limited access to the CNS.

PubMed Central

Shaw, J. S.; Carroll, J. A.; Alcock, P.; Main, B. G.

1989-01-01

1. A number of compounds were evaluated in an attempt to identify a kappa-opioid receptor agonist with limited access to the central nervous system. 2. Quaternary derivatives of the kappa-opioid agonists tifluadom, U-50488H and ethylketocyclazocine were essentially devoid of opioid activity in a range of isolated tissue preparations. 3. A novel compound - ICI 204448 - is described which produced a potent and naloxone-reversible inhibition of electrically-evoked contraction of the guinea-pig ileum, mouse vas deferens and rabbit vas deferens preparations. ICI 204448 was shown to displace the binding of the kappa-opioid ligand [3H]-bremazocine from guinea-pig cerebellum membranes. 4. Ex vivo binding studies in mice showed ICI 204448 to be well absorbed following subcutaneous administration. The brain levels achieved by ICI 20448 were substantially lower than those produced by kappa-agonists such as U-50488H and tifluadom. 5. A good correlation was found for a range of opioids between lipophilicity and degree of CNS penetration. PMID:2568146

Cell type-specific regulation of beta2-adrenoceptor mRNA by agonists.

PubMed

Danner, S; Lohse, M J

1997-07-16

Prolonged agonist stimulation of beta2-adrenoceptors results in receptor down-regulation which is often paralleled by a reduction of the corresponding mRNA. In this study, we investigated the agonist-dependent regulation of beta2-adrenoceptor mRNA in DDT1-MF2 smooth muscle cells and C6 glioma cells. In DDT1-MF2 cells the half-life of the mRNA was 12 h in monolayer compared to 2 h in suspension cultures. Under both conditions, the agonist isoproterenol reduced this half-life by a factor of 2. In contrast, in C6 glioma cells isoproterenol had no effect on the mRNA stability, even though it reduced mRNA levels by approximately 50%. Isoproterenol-induced downregulation of beta2-adrenoceptor mRNA was completely blocked in C6 cells by the presence of a protein synthesis inhibitor, while this was not so in DDT1-MF2-cells. These data show that beta2-adrenoceptor downregulation occurs via cell-type specific mechanisms.

Clinical use of deslorelin (GnRH agonist) in companion animals: a review.

PubMed

Lucas, X

2014-10-01

Over the years, many contraceptive medications have been developed for companion animals, but many secondary adverse effects have limited their use. A major advancement was achieved with the use of gonadotropin-releasing hormone (GnRH) analogues, mainly GnRH agonists, which mimic the effects of native GnRH. The development of effective low-dose, slow-release implants with potent agonists such as deslorelin (Suprelorin®, Virbac) have allowed their use to become widespread in recent years, with many potential benefits in companion animals. While the major application of deslorelin was initially male contraception, due to its two differing actions, either the stimulation of oestrus or the sterilization of fertility, its use has been increasing in the bitch as well. The aim of this study is to review the applications of deslorelin GnRH agonist implants in companion animal, such as dogs, cats and some exotic pets. © 2014 Blackwell Verlag GmbH.

Critical Pedagogy&apos;s Problem with Changing Teachers&apos; Dispositions towards Critical Teaching

ERIC Educational Resources Information Center

Neumann, Jacob W.

2013-01-01

Increasing teachers&apos; dispositions towards critical teaching is a fundamental goal for critical pedagogy. Because critical educational change cannot occur without teachers&apos; "buy-in," developing teachers&apos; inclination to implement critical teaching into their classrooms is a prerequisite for any successful critical pedagogy…

Appraisal of unimodal cues during agonistic interactions in Maylandia zebra

PubMed Central

Ben Ammar, Imen; Fernandez, Marie S.A.; Boyer, Nicolas; Attia, Joël; Fonseca, Paulo J.; Amorim, M. Clara P.; Beauchaud, Marilyn

2017-01-01

Communication is essential during social interactions including animal conflicts and it is often a complex process involving multiple sensory channels or modalities. To better understand how different modalities interact during communication, it is fundamental to study the behavioural responses to both the composite multimodal signal and each unimodal component with adequate experimental protocols. Here we test how an African cichlid, which communicates with multiple senses, responds to different sensory stimuli in a social relevant scenario. We tested Maylandia zebra males with isolated chemical (urine or holding water coming both from dominant males), visual (real opponent or video playback) and acoustic (agonistic sounds) cues during agonistic interactions. We showed that (1) these fish relied mostly on the visual modality, showing increased aggressiveness in response to the sight of a real contestant but no responses to urine or agonistic sounds presented separately, (2) video playback in our study did not appear appropriate to test the visual modality and needs more technical prospecting, (3) holding water provoked territorial behaviours and seems to be promising for the investigation into the role of the chemical channel in this species. Our findings suggest that unimodal signals are non-redundant but how different sensory modalities interplay during communication remains largely unknown in fish. PMID:28785523

Use of ß-adrenergic agonists in hybrid catfish

USDA-ARS?s Scientific Manuscript database

Ractopamine hydrochloride (RH) is a potent ß-adrenergic agonist that has been used in some species of fish to improve growth performance and dress out characteristics. While this metabolic modifier has been shown to have positive effects on growth of fish, little research has focused on the mechani...

Design and Discovery of Functionally Selective Serotonin 2C (5-HT2C) Receptor Agonists.

PubMed

Cheng, Jianjun; McCorvy, John D; Giguere, Patrick M; Zhu, Hu; Kenakin, Terry; Roth, Bryan L; Kozikowski, Alan P

2016-11-10

On the basis of the structural similarity of our previous 5-HT 2C agonists with the melatonin receptor agonist tasimelteon and the putative biological cross-talk between serotonergic and melatonergic systems, a series of new (2,3-dihydro)benzofuran-based compounds were designed and synthesized. The compounds were evaluated for their selectivity toward 5-HT 2A , 5-HT 2B , and 5-HT 2C receptors in the calcium flux assay with the ultimate goal to generate selective 5-HT 2C agonists. Selected compounds were studied for their functional selectivity by comparing their transduction efficiency at the G protein signaling pathway versus β-arrestin recruitment. The most functionally selective compound (+)-7e produced weak β-arrestin recruitment and also demonstrated less receptor desensitization compared to serotonin in both calcium flux and phosphoinositide (PI) hydrolysis assays. We report for the first time that selective 5-HT 2C agonists possessing weak β-arrestin recruitment can produce distinct receptor desensitization properties.

Simulations of Biased Agonists in the β2 Adrenergic Receptor with Accelerated Molecular Dynamics

PubMed Central

2013-01-01

The biased agonism of the G protein-coupled receptors (GPCRs), where in addition to a traditional G protein-signaling pathway a GPCR promotes intracellular signals though β-arrestin, is a novel paradigm in pharmacology. Biochemical and biophysical studies have suggested that a GPCR forms a distinct ensemble of conformations signaling through the G protein and β-arrestin. Here we report on the dynamics of the β2 adrenergic receptor bound to the β-arrestin and G protein-biased agonists and the empty receptor to further characterize the receptor conformational changes caused by biased agonists. We use conventional and accelerated molecular dynamics (aMD) simulations to explore the conformational transitions of the GPCR from the active state to the inactive state. We found that aMD simulations enable monitoring of the transition within the nanosecond time scale while capturing the known microscopic characteristics of the inactive states, such as the ionic lock, the inward position of F6.44, and water clusters. Distinct conformational states are shown to be stabilized by each biased agonist. In particular, in simulations of the receptor with the β-arrestin-biased agonist N-cyclopentylbutanepherine, we observe a different pattern of motions in helix 7 when compared to simulations with the G protein-biased agonist salbutamol that involves perturbations of the network of interactions within the NPxxY motif. Understanding the network of interactions induced by biased ligands and the subsequent receptor conformational shifts will lead to development of more efficient drugs. PMID:23879802

A cannabinoid 2 receptor agonist attenuates bone cancer-induced pain and bone loss

PubMed Central

Lozano, Alysia; Wright, Courtney; Vardanyan, Anna; King, Tamara; Largent-Milnes, Tally M.; Nelson, Mark; Jimenez-Andrade, Juan Miguel; Mantyh, Patrick W; Vanderah, Todd W.

2010-01-01

Aims Cannabinoid CB2 agonists have been shown to alleviate behavioral signs of inflammatory and neuropathic pain in animal models. AM1241, a CB2 agonist, does not demonstrate central nervous system side-effects seen with CB1 agonists such as hypothermia and catalepsy. Metastatic bone cancer causes severe pain in patients and is treated with analgesics such as opiates. Recent reports suggest that sustained opiates can produce paradoxical hyperalgesic actions and enhance bone destruction in a murine model of bone cancer. In contrast, CB2 selective agonists have been shown to reduce bone loss associated with a model of osteoporosis. Here we tested whether a CB2 agonist administered over a 7 day period inhibits bone cancer-induced pain as well as attenuates cancer-induced bone degradation. Main Methods A murine bone cancer model was used in which osteolytic sarcoma cells were injected into the intramedullary space of the distal end of the femur. Behavioral and radiographic image analysis was performed at days 7, 10 and 14 after injection of tumor cells into the femur. Key Findings Osteolytic sarcoma within the femur produced spontaneous and touch evoked behavioral signs of pain within the tumor-bearing limb. The systemic administration of AM1241 acutely or for 7 days significantly attenuated spontaneous and evoked pain in the inoculated limb. Sustained AM1241 significantly reduced bone loss and decreased the incidence of cancer-induced bone fractures. Significance These findings suggest a novel therapy for cancer-induced bone pain, bone loss and bone fracture while lacking many unwanted side effects seen with current treatments for bone cancer pain. PMID:20176037

Agonistic Human Antibodies Binding to Lecithin-Cholesterol Acyltransferase Modulate High Density Lipoprotein Metabolism*

PubMed Central

Gunawardane, Ruwanthi N.; Fordstrom, Preston; Piper, Derek E.; Masterman, Stephanie; Siu, Sophia; Liu, Dongming; Brown, Mike; Lu, Mei; Tang, Jie; Zhang, Richard; Cheng, Janet; Gates, Andrew; Meininger, David; Chan, Joyce; Carlson, Tim; Walker, Nigel; Schwarz, Margrit; Delaney, John; Zhou, Mingyue

2016-01-01

Drug discovery opportunities where loss-of-function alleles of a target gene link to a disease-relevant phenotype often require an agonism approach to up-regulate or re-establish the activity of the target gene. Antibody therapy is increasingly recognized as a favored drug modality due to multiple desirable pharmacological properties. However, agonistic antibodies that enhance the activities of the target enzymes are rarely developed because the discovery of agonistic antibodies remains elusive. Here we report an innovative scheme of discovery and characterization of human antibodies capable of binding to and agonizing a circulating enzyme lecithin cholesterol acyltransferase (LCAT). Utilizing a modified human LCAT protein with enhanced enzymatic activity as an immunogen, we generated fully human monoclonal antibodies using the XenoMouseTM platform. One of the resultant agonistic antibodies, 27C3, binds to and substantially enhances the activity of LCAT from humans and cynomolgus macaques. X-ray crystallographic analysis of the 2.45 Å LCAT-27C3 complex shows that 27C3 binding does not induce notable structural changes in LCAT. A single administration of 27C3 to cynomolgus monkeys led to a rapid increase of plasma LCAT enzymatic activity and a 35% increase of the high density lipoprotein cholesterol that was observed up to 32 days after 27C3 administration. Thus, this novel scheme of immunization in conjunction with high throughput screening may represent an effective strategy for discovering agonistic antibodies against other enzyme targets. 27C3 and other agonistic human anti-human LCAT monoclonal antibodies described herein hold potential for therapeutic development for the treatment of dyslipidemia and cardiovascular disease. PMID:26644477

Allosteric activation of the follicle-stimulating hormone (FSH) receptor by selective, nonpeptide agonists.

PubMed

Yanofsky, Stephen D; Shen, Emily S; Holden, Frank; Whitehorn, Erik; Aguilar, Barbara; Tate, Emily; Holmes, Christopher P; Scheuerman, Randall; MacLean, Derek; Wu, May M; Frail, Donald E; López, Francisco J; Winneker, Richard; Arey, Brian J; Barrett, Ronald W

2006-05-12

The pituitary glycoprotein hormones, luteinizing hormone and follicle-stimulating hormone (FSH), act through their cognate receptors to initiate a series of coordinated physiological events that results in germ cell maturation. Given the importance of FSH in regulating folliculogenesis and fertility, the development of FSH mimetics has been sought to treat infertility. Currently, purified and recombinant human FSH are the only FSH receptor (FSH-R) agonists available for infertility treatment. By screening unbiased combinatorial chemistry libraries, using a cAMP-responsive luciferase reporter assay, we discovered thiazolidinone agonists (EC50's = 20 microm) of the human FSH-R. Subsequent analog library screening and parallel synthesis optimization resulted in the identification of a potent agonist (EC50 = 2 nm) with full efficacy compared with FSH that was FSH-R-selective and -dependent. The compound mediated progesterone production in Y1 cells transfected with the human FSH-R (EC50 = 980 nm) and estradiol production from primary rat ovarian granulosa cells (EC50 = 10.5 nm). This and related compounds did not compete with FSH for binding to the FSH-R. Use of human FSH/thyroid-stimulating hormone (TSH) receptor chimeras suggested a novel mechanism for receptor activation through a binding site independent of the natural hormone binding site. This study is the first report of a high affinity small molecule agonist that activates a glycoprotein hormone receptor through an allosteric mechanism. The small molecule FSH receptor agonists described here could lead to an oral alternative to the current parenteral FSH treatments used clinically to induce ovarian stimulation for both in vivo and in vitro fertilization therapy.

Pharmacologic Treatment with GABAB Receptor Agonist of Methamphetamine-Induced Cognitive Impairment in Mice

PubMed Central

Mizoguchi, Hiroyuki; Yamada, Kiyofumi

2011-01-01

Methamphetamine (METH) is a highly addictive drug, and addiction to METH has increased to epidemic proportions worldwide. Chronic use of METH causes psychiatric symptoms, such as hallucinations and delusions, and long-term cognitive deficits, which are indistinguishable from paranoid schizophrenia. The GABA receptor system is known to play a significant role in modulating the dopaminergic neuronal system, which is related to behavioral changes induced by drug abuse. However, few studies have investigated the effects of GABA receptor agonists on cognitive deficits induced by METH. In the present review, we show that baclofen, a GABA receptor agonist, is effective in treating METH-induced impairment of object recognition memory and prepulse inhibition (PPI) of the startle reflex, a measure of sensorimotor gating in mice. Acute and repeated treatment with METH induced a significant impairment of PPI. Furthermore, repeated but not acute treatment of METH resulted in a long-lasting deficit of object recognition memory. Baclofen, a GABAB receptor agonist, dose-dependently ameliorated the METH-induced PPI deficits and object recognition memory impairment in mice. On the other hand, THIP, a GABAA receptor agonist, had no effect on METH-induced cognitive deficits. These results suggest that GABAB receptors may constitute a putative new target in treating cognitive deficits in chronic METH users. PMID:21886573

Effects of different isoforms of apoE on aggregation of the α-synuclein protein implicated in Parkinson's disease.

PubMed

Emamzadeh, Fatemeh Nouri; Aojula, Harmesh; McHugh, Patrick C; Allsop, David

2016-04-08

Parkinson's disease is a progressive brain disorder due to the degeneration of dopaminergic neurons in the substantia nigra. The accumulation of aggregated forms of α-synuclein protein into Lewy bodies is one of the characteristic features of this disease although the pathological role of any such protein deposits in causing neurodegeneration remains elusive. Here, the effects of different apolipoprotein E isoforms (apoE2, apoE3, apoE4) on the aggregation of α-synuclein in vitro were examined using thioflavin T assays and also an immunoassay to detect the formation of multimeric forms. Our results revealed that the aggregation of α-synuclein is influenced by apoE concentration. At low concentrations of apoE (<15nM), all of the isoforms were able to increase the aggregation of α-synuclein (50μM), with apoE4 showing the greatest stimulatory effect. This is in contrast to a higher concentration (>15nM) of these isoforms, where a decrease in the aggregation of α-synuclein was noted. The data show that exceptionally low levels of apoE may seed α-syn aggregation, which could potentially lead to the pathogenesis of α-synuclein-induced neurodegeneration. On the other hand, higher levels of apoE could potentially lower the degree of α-synuclein aggregation and confer protection. The differential effects noted with apoE4 could explain why this particular isoform results in an earlier age of onset for Parkinson's disease. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Alcohol Screening among Opioid Agonist Patients in a Primary Care Clinic and an Opioid Treatment Program.

PubMed

Klimas, Jan; Muench, John; Wiest, Katharina; Croff, Raina; Rieckman, Traci; McCarty, Dennis

2015-01-01

Problem alcohol use is associated with adverse health and economic outcomes, especially among people in opioid agonist treatment. Screening, brief intervention, and referral to treatment (SBIRT) are effective in reducing alcohol use; however, issues involved in SBIRT implementation among opioid agonist patients are unknown. To assess identification and treatment of alcohol use disorders, we reviewed clinical records of opioid agonist patients screened for an alcohol use disorder in a primary care clinic (n = 208) and in an opioid treatment program (n = 204) over a two-year period. In the primary care clinic, 193 (93%) buprenorphine patients completed an annual alcohol screening and six (3%) had elevated AUDIT scores. In the opioid treatment program, an alcohol abuse or dependence diagnosis was recorded for 54 (27%) methadone patients. Practitioner focus groups were completed in the primary care (n = 4 physicians) and the opioid treatment program (n = 11 counselors) to assess experience with and attitudes towards screening opioid agonist patients for alcohol use disorders. Focus groups suggested that organizational, structural, provider, patient, and community variables hindered or fostered alcohol screening. Alcohol screening is feasible among opioid agonist patients. Effective implementation, however, requires physician training and systematic changes in workflow.

Agonist-induced conformational changes in the G-protein-coupling domain of the β2 adrenergic receptor

PubMed Central

Ghanouni, Pejman; Steenhuis, Jacqueline J.; Farrens, David L.; Kobilka, Brian K.

2001-01-01

The majority of extracellular physiologic signaling molecules act by stimulating GTP-binding protein (G-protein)-coupled receptors (GPCRs). To monitor directly the formation of the active state of a prototypical GPCR, we devised a method to site specifically attach fluorescein to an endogenous cysteine (Cys-265) at the cytoplasmic end of transmembrane 6 (TM6) of the β2 adrenergic receptor (β2AR), adjacent to the G-protein-coupling domain. We demonstrate that this tag reports agonist-induced conformational changes in the receptor, with agonists causing a decline in the fluorescence intensity of fluorescein-β2AR that is proportional to the biological efficacy of the agonist. We also find that agonists alter the interaction between the fluorescein at Cys-265 and fluorescence-quenching reagents localized to different molecular environments of the receptor. These observations are consistent with a rotation and/or tilting of TM6 on agonist activation. Our studies, when compared with studies of activation in rhodopsin, indicate a general mechanism for GPCR activation; however, a notable difference is the relatively slow kinetics of the conformational changes in the β2AR, which may reflect the different energetics of activation by diffusible ligands. PMID:11353823

Hexim1 heterozygosity stabilizes atherosclerotic plaque and decreased steatosis in ApoE null mice fed atherogenic diet.

PubMed

Dhar-Mascareno, Manya; Rozenberg, Inna; Iqbal, Jahangir; Hussain, M Mahmood; Beckles, Daniel; Mascareno, Eduardo

2017-02-01

Hexim-1 is an inhibitor of RNA polymerase II transcription elongation. Decreased Hexim-1 expression in animal models of chronic diseases such as left ventricular hypertrophy, obesity and cancer triggered significant changes in adaptation and remodeling. The main aim of this study was to evaluate the role of Hexim1 in lipid metabolism focused in the progression of atherosclerosis and steatosis. We used the C57BL6 apolipoprotein E (ApoE null) crossed bred to C57BL6Hexim1 heterozygous mice to obtain ApoE null - Hexim1 heterozygous mice (ApoE-HT). Both ApoE null backgrounds were fed high fat diet for twelve weeks. Then, we evaluated lipid metabolism, atherosclerotic plaque formation and liver steatosis. In order to understand changes in the transcriptome of both backgrounds during the progression of steatosis, we performed Affymetrix mouse 430 2.0 microarray. After 12 weeks of HFD, ApoE null and ApoE-HT showed similar increase of cholesterol and triglycerides in plasma. Plaque composition was altered in ApoE-HT. Additionally, liver triglycerides and steatosis were decreased in ApoE-HT mice. Affymetrix analysis revealed that decreased steatosis might be due to impaired inducible SOCS3 expression in ApoE-HT mice. In conclusion, decreased Hexim-1 expression does not alter cholesterol metabolism in ApoE null background after HFD. However, it promotes stable atherosclerotic plaque and decreased steatosis by promoting the anti-inflammatory TGFβ pathway and blocking the expression of the inducible and pro-inflammatory expression of SOCS3 respectively. Published by Elsevier Ltd.

A Novel Aminotetralin-Type Serotonin (5-HT) 2C Receptor-Specific Agonist and 5-HT2A Competitive Antagonist/5-HT2B Inverse Agonist with Preclinical Efficacy for Psychoses

PubMed Central

Morgan, Drake; Felsing, Daniel; Kondabolu, Krishnakanth; Rowland, Neil E.; Robertson, Kimberly L.; Sakhuja, Rajeev; Booth, Raymond G.

2014-01-01

Development of 5-HT2C agonists for treatment of neuropsychiatric disorders, including psychoses, substance abuse, and obesity, has been fraught with difficulties, because the vast majority of reported 5-HT2C selective agonists also activate 5-HT2A and/or 5-HT2B receptors, potentially causing hallucinations and/or cardiac valvulopathy. Herein is described a novel, potent, and efficacious human 5-HT2C receptor agonist, (−)-trans-(2S,4R)-4-(3′[meta]-bromophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (−)-MBP), that is a competitive antagonist and inverse agonist at human 5-HT2A and 5-HT2B receptors, respectively. (−)-MBP has efficacy comparable to the prototypical second-generation antipsychotic drug clozapine in three C57Bl/6 mouse models of drug-induced psychoses: the head-twitch response elicited by [2,5]-dimethoxy-4-iodoamphetamine; hyperlocomotion induced by MK-801 [(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (dizocilpine maleate)]; and hyperlocomotion induced by amphetamine. (−)-MBP, however, does not alter locomotion when administered alone, distinguishing it from clozapine, which suppresses locomotion. Finally, consumption of highly palatable food by mice was not increased by (−)-MBP at a dose that produced at least 50% maximal efficacy in the psychoses models. Compared with (−)-MBP, the enantiomer (+)-MBP was much less active across in vitro affinity and functional assays using mouse and human receptors and also translated in vivo with comparably lower potency and efficacy. Results indicate a 5-HT2C receptor-specific agonist, such as (−)-MBP, may be pharmacotherapeutic for psychoses, without liability for obesity, hallucinations, heart disease, sedation, or motoric disorders. PMID:24563531

Peroxisome proliferator-activated receptor agonists modulate neuropathic pain: a link to chemokines?

PubMed Central

Freitag, Caroline M.; Miller, Richard J.

2014-01-01

Chronic pain presents a widespread and intractable medical problem. While numerous pharmaceuticals are used to treat chronic pain, drugs that are safe for extended use and highly effective at treating the most severe pain do not yet exist. Chronic pain resulting from nervous system injury (neuropathic pain) is common in conditions ranging from multiple sclerosis to HIV-1 infection to type II diabetes. Inflammation caused by neuropathy is believed to contribute to the generation and maintenance of neuropathic pain. Chemokines are key inflammatory mediators, several of which (MCP-1, RANTES, MIP-1α, fractalkine, SDF-1 among others) have been linked to chronic, neuropathic pain in both human conditions and animal models. The important roles chemokines play in inflammation and pain make them an attractive therapeutic target. Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear receptors known for their roles in metabolism. Recent research has revealed that PPARs also play a role in inflammatory gene repression. PPAR agonists have wide-ranging effects including inhibition of chemokine expression and pain behavior reduction in animal models. Experimental evidence suggests a connection between the pain ameliorating effects of PPAR agonists and suppression of inflammatory gene expression, including chemokines. In early clinical research, one PPARα agonist, palmitoylethanolamide (PEA), shows promise in relieving chronic pain. If this link can be better established, PPAR agonists may represent a new drug therapy for neuropathic pain. PMID:25191225

Monitoring of PAEMs and beta-agonists in urine for a small group of experimental subjects and PAEs and beta-agonists in drinking water consumed by the same subjects.

PubMed

Liou, Saou-Hsing; Yang, Gordon C C; Wang, Chih-Lung; Chiu, Yu-Han

2014-07-30

This 5-month study contains two parts: (1) to monitor the concentrations of 11 phthalate esters metabolites (PAEMs) and two beta-agonists in human urine samples collected from a small group of consented participants including 16 females and five males; and (2) to analyze the residues of phthalate esters (PAEs) and beta-agonists in various categories of drinking water consumed by the same group of subjects. Each category of human urine and drinking water had 183 samples of its own. The analytical results showed that nine PAEMs were detected in human urine and eight PAEs were detected in drinking water samples. It was found that average concentrations of PAEMs increased as the age increased, but no significant difference between sexes. Further, using the principal component analysis, the loadings of age effect were found to be two times greater than that of gender effect in terms of four DEHP metabolites. Regarding beta-agonists of concern (i.e., ractopamine and salbutamol), they were neither detected in human urine nor drinking water samples in this study. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of bezafibrate, PPAR pan-agonist, and GW501516, PPARdelta agonist, on development of steatohepatitis in mice fed a methionine- and choline-deficient diet.

PubMed

Nagasawa, Tatsuya; Inada, Yoichi; Nakano, Shigeru; Tamura, Toru; Takahashi, Tetsuaki; Maruyama, Kazuyasu; Yamazaki, Yoshinobu; Kuroda, Junji; Shibata, Nobuo

2006-04-24

We evaluated the effects of bezafibrate, a peroxisome proliferator-activated receptor (PPAR) pan-agonist, and GW501516, a PPARdelta agonist, on mice fed a methionine- and choline-deficient (MCD) diet, a model of non-alcholic steatohepatitis (NASH), to investigate (a) the efficacy of bezafibrate against non-alcholic steatohepatitis and (b) the relation between non-alcholic steatohepatitis and the functional role of PPARdelta. Bezafibrate (50 or 100 mg/kg/day) and GW501516 (10 mg/kg/day) were administered by gavage once a day for 5 weeks. Hepatic lipid contents, plasma triglyceride, high density lipoprotein (HDL)-cholesterol and alanine aminotransferase (ALT) concentrations were evaluated, as were histopathological changes in the liver and hepatic mRNA expression levels. Bezafibrate and GW501516 inhibited the MCD-diet-induced elevations of hepatic triglyceride and thiobarbituric acid-reactants contents and the histopathological increases in fatty droplets within hepatocytes, liver inflammation and number of activated hepatic stellate cells. In this model, bezafibrate and GW501516 increased the levels of hepatic mRNAs associated with fatty acid beta-oxidation [acyl-CoA oxidase (ACO), carnitine palmitoyltransferase-1 (CPT-1), liver-fatty acid binding protein (L-FABP) and peroxisomal ketothiolase], and reduced the levels of those associated with inflammatory cytokines or chemokine [transforming growth factor (TGF)-beta1, interleukin (IL)-6, IL-1beta, monocyte chemoattractant protein (MCP)-1, tumor necrosis factor (TNF) alpha and nuclear factor (NF)-kappaB1]. In addition, bezafibrate characteristically reduced the elevation in the level of plasma ALT, but enhanced that in plasma adiponectin and increased the mRNA expression levels of its receptors (adiponectin receptors 1 and 2). These results suggest that (a) bezafibrate (especially) and GW501516 might improve hepatic steatosis via an improvement in fatty acid beta-oxidation and a direct prevention of inflammation, (b

ApoE gene and exceptional longevity: Insights from three independent cohorts.

PubMed

Garatachea, Nuria; Emanuele, Enzo; Calero, Miguel; Fuku, Noriyuki; Arai, Yasumichi; Abe, Yukiko; Murakami, Haruka; Miyachi, Motohiko; Yvert, Thomas; Verde, Zoraida; Zea, Ma Ascensión; Venturini, Letizia; Santiago, Catalina; Santos-Lozano, Alejandro; Rodríguez-Romo, Gabriel; Ricevuti, Giovanni; Hirose, Nobuyoshi; Rábano, Alberto; Lucia, Alejandro

2014-05-01

The ApoE gene is associated with the risk of Alzheimer or cardiovascular disease but its influence on exceptional longevity (EL) is uncertain. Our primary purpose was to determine, using a case-control design, if the ApoE gene is associated with EL. We compared ApoE allele/genotype frequencies among the following cohorts: cases (centenarians, most with 1+ major disease condition; n=163, 100-111years) and healthy controls (n=1039, 20-85years) from Spain; disease-free cases (centenarians; n=79, 100-104years) and healthy controls (n=597, age 27-81years) from Italy; and cases (centenarians and semi-supercentenarians, most with 1+ major disease condition; n=729, 100-116years) and healthy controls (n=498, 23-59years) from Japan. Our main findings were twofold. First, the ε4-allele was negatively associated with EL in the three cohorts, with the following odds ratio (OR) values (adjusted by sex) having been found: 0.55 (95% confidence interval (CI): 0.33, 0.94), P=0.030 (Spain); 0.41 (95%CI: 0.18, 0.99), P=0.05 (Italy); and 0.35 (95%CI: 0.26, 0.57), P<0.001 (Japan). Second, although no association was found in the Spanish cohort (OR=1.42 (95%CI: 0.89, 2.26), P=0.145), the ε2-allele was positively associated with EL in the Italian (OR=2.14 (95%CI: 1.18, 3.45), P=0.01) and Japanese subjects (OR=1.81 (95%CI: 1.25, 2.63), P=0.002). Notwithstanding the limitations of case-control designs, our data suggest that the ApoE might be a candidate to influence EL. The ε4-allele appears to decrease the likelihood of reaching EL among individuals of different ethnic/geographic origins. An additional, novel finding of our study was that the ε2-allele might favor EL, at least in the Italian and Japanese cohorts. Copyright © 2014 Elsevier Inc. All rights reserved.

Hypotensive effects of ghrelin receptor agonists mediated through a novel receptor.

PubMed

Callaghan, Brid; Kosari, Samin; Pustovit, Ruslan V; Sartor, Daniela M; Ferens, Dorota; Ban, Kung; Baell, Jonathan; Nguyen, Trung V; Rivera, Leni R; Brock, James A; Furness, John B

2014-03-01

Some agonists of ghrelin receptors cause rapid decreases in BP. The mechanisms by which they cause hypotension and the pharmacology of the receptors are unknown. The effects of ligands of ghrelin receptors were investigated in rats in vivo, on isolated blood vessels and on cells transfected with the only molecularly defined ghrelin receptor, growth hormone secretagogue receptor 1a (GHSR1a). Three agonists of GHSR1a receptors, ulimorelin, capromorelin and CP464709, caused a rapid decrease in BP in the anaesthetized rat. The effect was not reduced by either of two GHSR1a antagonists, JMV2959 or YIL781, at doses that blocked effects on colorectal motility, in vivo. The rapid hypotension was not mimicked by ghrelin, unacylated ghrelin or the unacylated ghrelin receptor agonist, AZP531. The early hypotension preceded a decrease in sympathetic nerve activity. Early hypotension was not reduced by hexamethonium or by baroreceptor (sino-aortic) denervation. Ulimorelin also relaxed isolated segments of rat mesenteric artery, and, less potently, relaxed aorta segments. The vascular relaxation was not reduced by JMV2959 or YIL781. Ulimorelin, capromorelin and CP464709 activated GHSR1a in transfected HEK293 cells at nanomolar concentrations. JMV2959 and YIL781 both antagonized effects in these cells, with their pA2 values at the GHSR1a receptor being 6.55 and 7.84. Our results indicate a novel vascular receptor or receptors whose activation by ulimorelin, capromorelin and CP464709 lowered BP. This receptor is activated by low MW GHSR1a agonists, but is not activated by ghrelin. © 2013 The British Pharmacological Society.

Hypotensive effects of ghrelin receptor agonists mediated through a novel receptor

PubMed Central

Callaghan, Brid; Kosari, Samin; Pustovit, Ruslan V; Sartor, Daniela M; Ferens, Dorota; Ban, Kung; Baell, Jonathan; Nguyen, Trung V; Rivera, Leni R; Brock, James A; Furness, John B

2014-01-01

BACKGROUND AND PURPOSE Some agonists of ghrelin receptors cause rapid decreases in BP. The mechanisms by which they cause hypotension and the pharmacology of the receptors are unknown. EXPERIMENTAL APPROACH The effects of ligands of ghrelin receptors were investigated in rats in vivo, on isolated blood vessels and on cells transfected with the only molecularly defined ghrelin receptor, growth hormone secretagogue receptor 1a (GHSR1a). KEY RESULTS Three agonists of GHSR1a receptors, ulimorelin, capromorelin and CP464709, caused a rapid decrease in BP in the anaesthetized rat. The effect was not reduced by either of two GHSR1a antagonists, JMV2959 or YIL781, at doses that blocked effects on colorectal motility, in vivo. The rapid hypotension was not mimicked by ghrelin, unacylated ghrelin or the unacylated ghrelin receptor agonist, AZP531. The early hypotension preceded a decrease in sympathetic nerve activity. Early hypotension was not reduced by hexamethonium or by baroreceptor (sino-aortic) denervation. Ulimorelin also relaxed isolated segments of rat mesenteric artery, and, less potently, relaxed aorta segments. The vascular relaxation was not reduced by JMV2959 or YIL781. Ulimorelin, capromorelin and CP464709 activated GHSR1a in transfected HEK293 cells at nanomolar concentrations. JMV2959 and YIL781 both antagonized effects in these cells, with their pA2 values at the GHSR1a receptor being 6.55 and 7.84. CONCLUSIONS AND IMPLICATIONS Our results indicate a novel vascular receptor or receptors whose activation by ulimorelin, capromorelin and CP464709 lowered BP. This receptor is activated by low MW GHSR1a agonists, but is not activated by ghrelin. PMID:24670149

GPR40 partial agonists and AgoPAMs: Differentiating effects on glucose and hormonal secretions in the rodent

PubMed Central

Pachanski, Michele J.; Kirkland, Melissa E.; Kosinski, Daniel T.; Mane, Joel; Cheewatrakoolpong, Boonlert; Xue, Jiyan; Szeto, Daphne; Forrest, Gail; Miller, Corin; Bunzel, Michelle; Plummer, Christopher W.; Chobanian, Harry R.; Miller, Michael W.; Souza, Sarah; Thomas-Fowlkes, Brande S.; Ogawa, Aimie M.; Weinglass, Adam B.; Di Salvo, Jerry; Li, Xiaoyan; Feng, Yue; Tatosian, Daniel A.; Howard, Andrew D.; Colletti, Steven L.

2017-01-01

GPR40 agonists are effective antidiabetic agents believed to lower glucose through direct effects on the beta cell to increase glucose stimulated insulin secretion. However, not all GPR40 agonists are the same. Partial agonists lower glucose through direct effects on the pancreas, whereas GPR40 AgoPAMs may incorporate additional therapeutic effects through increases in insulinotrophic incretins secreted by the gut. Here we describe how GPR40 AgoPAMs stimulate both insulin and incretin secretion in vivo over time in diabetic GK rats. We also describe effects of AgoPAMs in vivo to lower glucose and body weight beyond what is seen with partial GPR40 agonists in both the acute and chronic setting. Further comparisons of the glucose lowering profile of AgoPAMs suggest these compounds may possess greater glucose control even in the presence of elevated glucagon secretion, an unexpected feature observed with both acute and chronic treatment with AgoPAMs. Together these studies highlight the complexity of GPR40 pharmacology and the potential additional benefits AgoPAMs may possess above partial agonists for the diabetic patient. PMID:29053717

Impaired β-arrestin recruitment and reduced desensitization by non-catechol agonists of the D1 dopamine receptor.

PubMed

Gray, David L; Allen, John A; Mente, Scot; O'Connor, Rebecca E; DeMarco, George J; Efremov, Ivan; Tierney, Patrick; Volfson, Dmitri; Davoren, Jennifer; Guilmette, Edward; Salafia, Michelle; Kozak, Rouba; Ehlers, Michael D

2018-02-14

Selective activation of dopamine D1 receptors (D1Rs) has been pursued for 40 years as a therapeutic strategy for neurologic and psychiatric diseases due to the fundamental role of D1Rs in motor function, reward processing, and cognition. All known D1R-selective agonists are catechols, which are rapidly metabolized and desensitize the D1R after prolonged exposure, reducing agonist response. As such, drug-like selective D1R agonists have remained elusive. Here we report a novel series of selective, potent non-catechol D1R agonists with promising in vivo pharmacokinetic properties. These ligands stimulate adenylyl cyclase signaling and are efficacious in a rodent model of Parkinson's disease after oral administration. They exhibit distinct binding to the D1R orthosteric site and a novel functional profile including minimal receptor desensitization, reduced recruitment of β-arrestin, and sustained in vivo efficacy. These results reveal a novel class of D1 agonists with favorable drug-like properties, and define the molecular basis for catechol-specific recruitment of β-arrestin to D1Rs.

Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors.

PubMed

Koshimizu, Taka-Aki; Kashiwazaki, Aki; Taniguchi, Junichi

2016-05-03

Reducing Na(+) in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na(+)-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na(+) sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na(+) increased cell surface [(3)H]AVP binding and decreased receptor internalization. Substitution of Na(+) by Cs(+) or NH4(+) inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na(+) over Cs(+). Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations.

Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors

PubMed Central

Koshimizu, Taka-aki; Kashiwazaki, Aki; Taniguchi, Junichi

2016-01-01

Reducing Na+ in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na+-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na+ sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na+ increased cell surface [3H]AVP binding and decreased receptor internalization. Substitution of Na+ by Cs+ or NH4+ inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na+ over Cs+. Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations. PMID:27138239

Behavioural and biochemical responses following activation of midbrain dopamine pathways by receptor selective neurokinin agonists.

PubMed

Elliott, P J; Mason, G S; Stephens-Smith, M; Hagan, R M

1991-06-01

Preferential activation of mesolimbic and nigro-striatal dopamine (DA) pathways by receptor-selective and peptidase-resistant neurokinin (NK) agonists is reported. The DA cell body region of the mesolimbic pathway appears to be activated by NK agonists selective for NK-1 and NK-3 receptors whereas the DA cell bodies in the substantia nigra are under an excitatory NK-2 receptor-mediated influence. Stimulation of the mesolimbic DA pathway by NK-1 (Ava[L-Pro9,N-Me-Leu10]SP (7-11) [GR73632]) or NK-3 (Senktide) agonists increase locomotor activity. Additional studies showed that this elevated motor response observed after intra-VTA infusion of GR73632 was accompanied by a corresponding increase in DA turnover in the terminal fields of this pathway. Similarly, unilateral activation of the nigro-striatal DA pathway by NK-2 selective agonists (Ava (D-Pro9) SP (7-11) [GR51667] or [Lys3,Gly8,R-Lac-Leu9]NKA (3-10) [GR64349]) elicit contralateral rotational activity and an increase in DA turnover in the ipsilateral striatum. The rotational response was attenuated by prior administration of an NK-2 antagonist (cyclo (Gln, Trp, Phe, Gly, Leu, Met)] L-659877]) into the nigra. Peripheral injection of haloperidol, a DA antagonist, also blocked the NK-2 agonist induced rotations.

Agonist antibody that induces human malignant cells to kill one another

PubMed Central

Yea, Kyungmoo; Zhang, Hongkai; Xie, Jia; Jones, Teresa M.; Lin, Chih-Wei; Francesconi, Walter; Berton, Fulvia; Fallahi, Mohammad; Sauer, Karsten; Lerner, Richard A.

2015-01-01

An attractive, but as yet generally unrealized, approach to cancer therapy concerns discovering agents that change the state of differentiation of the cancer cells. Recently, we discovered a phenomenon that we call “receptor pleiotropism” in which agonist antibodies against known receptors induce cell fates that are very different from those induced by the natural agonist to the same receptor. Here, we show that one can take advantage of this phenomenon to convert acute myeloblastic leukemic cells into natural killer cells. Upon induction with the antibody, these leukemic cells enter into a differentiation cascade in which as many as 80% of the starting leukemic cells can be differentiated. The antibody-induced killer cells make large amounts of perforin, IFN-γ, and granzyme B and attack and kill other members of the leukemic cell population. Importantly, induction of killer cells is confined to transformed cells, in that normal bone marrow cells are not induced to form killer cells. Thus, it seems possible to use agonist antibodies to change the differentiation state of cancer cells into those that attack and kill other members of the malignant clone from which they originate. PMID:26487683

Effect of a muscarinic M3 receptor agonist on gastric motility.

PubMed

Chiba, Toshimi; Kudara, Norihiko; Sato, Masaki; Inomata, Masaaki; Orii, Seishi; Suzuki, Kazuyuki

2007-11-01

Muscarinic M3 receptors exist in the gastrointestinal wall in humans and the muscarinic M3 agonist cevimeline hydrochloride (Evoxac) is a candidate therapeutic agent for the treatment of xerostomia in Sjögren's syndrome. However, M3 receptor agonists are not known to show efficacy for diseases associated with abnormal gastrointestinal motility. Herein the effects are reported of cevimeline on gastric motility in two patients with non-ulcer dyspepsia. The patients both received long-term proton pump inhibitor therapy for 6 months, but their symptoms persisted. Then cevimeline was administered orally for 8 weeks at 30 mg three times daily (90 mg/day) and their dyspepsia symptoms improved. Electrogastrography was performed to examine gastric motility before and after administration of the M3 agonist. The fasting or nocturnal wave rate was significantly increased after administration compared with before administration, but no significant postprandial changes were seen. No adverse effects of cevimeline were observed. This drug might be a candidate therapeutic agent for non-ulcer dyspepsia. Because its postprandial effects on gastrointestinal motility are unclear, a dose-finding clinical study should be performed in the future.

Evaluation of Mucociliary Clearance by Three Dimension Micro-CT-SPECT in Guinea Pig: Role of Bitter Taste Agonists.

PubMed

Ortiz, Jose Luis; Ortiz, Amparo; Milara, Javier; Armengot, Miguel; Sanz, Celia; Compañ, Desamparados; Morcillo, Esteban; Cortijo, Julio

2016-01-01

Different image techniques have been used to analyze mucociliary clearance (MCC) in humans, but current small animal MCC analysis using in vivo imaging has not been well defined. Bitter taste receptor (T2R) agonists increase ciliary beat frequency (CBF) and cause bronchodilation but their effects in vivo are not well understood. This work analyzes in vivo nasal and bronchial MCC in guinea pig animals using three dimension (3D) micro-CT-SPECT images and evaluates the effect of T2R agonists. Intranasal macroaggreggates of albumin-Technetium 99 metastable (MAA-Tc99m) and lung nebulized Tc99m albumin nanocolloids were used to analyze the effect of T2R agonists on nasal and bronchial MCC respectively, using 3D micro-CT-SPECT in guinea pig. MAA-Tc99m showed a nasal mucociliary transport rate of 0.36 mm/min that was increased in presence of T2R agonist to 0.66 mm/min. Tc99m albumin nanocolloids were homogeneously distributed in the lung of guinea pig and cleared with time-dependence through the bronchi and trachea of guinea pig. T2R agonist increased bronchial MCC of Tc99m albumin nanocolloids. T2R agonists increased CBF in human nasal ciliated cells in vitro and induced bronchodilation in human bronchi ex vivo. In summary, T2R agonists increase MCC in vivo as assessed by 3D micro-CT-SPECT analysis.

Differentiation of δ, μ, and κ opioid receptor agonists based on pharmacophore development and computed physicochemical properties

NASA Astrophysics Data System (ADS)

Filizola, Marta; Villar, Hugo O.; Loew, Gilda H.

2001-04-01

Compounds that bind with significant affinity to the opioid receptor types, δ, μ, and κ, with different combinations of activation and inhibition at these three receptors could be promising behaviorally selective agents. Working on this hypothesis, the chemical moieties common to three different sets of opioid receptor agonists with significant affinity for each of the three receptor types δ, μ, or κ were identified. Using a distance analysis approach, common geometric arrangements of these chemical moieties were found for selected δ, μ, or κ opioid agonists. The chemical and geometric commonalities among agonists at each opioid receptor type were then compared with a non-specific opioid recognition pharmacophore recently developed. The comparison provided identification of the additional requirements for activation of δ, μ, and κ opioid receptors. The distance analysis approach was able to clearly discriminate κ-agonists, while global molecular properties for all compounds were calculated to identify additional requirements for activation of δ and μ receptors. Comparisons of the combined geometric and physicochemical properties calculated for each of the three sets of agonists allowed the determination of unique requirements for activation of each of the three opioid receptors. These results can be used to improve the activation selectivity of known opioid agonists and as a guide for the identification of novel selective opioid ligands with potential therapeutic usefulness.

Divergent systemic and local inflammatory response to hind limb demand ischemia in wild-type and ApoE-/- mice.

PubMed

Crawford, Robert S; Albadawi, Hassan; Robaldo, Alessandro; Peck, Michael A; Abularrage, Christopher J; Yoo, Hyung-Jin; Lamuraglia, Glenn M; Watkins, Michael T

2013-08-01

We designed studies to determine whether the ApoE-/- phenotype modulates the local skeletal muscle and systemic inflammatory (plasma) responses to lower extremity demand ischemia. The ApoE-/- phenotype is an experimental model for atherosclerosis in humans. Aged female ApoE-/- and C57BL6 mice underwent femoral artery ligation, then were divided into sedentary and demand ischemia (exercise) groups on day 14. We assessed baseline and postexercise limb perfusion and hind limb function. On day 14, animals in the demand ischemia group underwent daily treadmill exercise through day 28. Sedentary mice were not exercised. On day 28, we harvested plasma and skeletal muscle from ischemic limbs from sedentary and exercised mice. We assayed muscle for angiogenic and proinflammatory proteins, markers of skeletal muscle regeneration, and evidence of skeletal muscle fiber maturation. Hind limb ischemia was similar in ApoE-/- and C57 mice before the onset of exercise. Under sedentary conditions, plasma vascular endothelial cell growth factor and interleukin-6, but not keratinocyte chemoattractant factor (KC) or macrophage inflammatory protein-2 (MIP-2), were higher in ApoE (P < 0.0001). After exercise, plasma levels of vascular endothelial cell growth factor, KC, and MIP-2, but not IL-6, were lower in ApoE (P < 0.004). The cytokines KC and MIP-2 in muscle were greater in exercised ApoE-/- mice compared with C57BL6 mice (P = 0.01). Increased poly-ADP-ribose activity and mature muscle regeneration were associated with demand ischemia in the C57BL6 mice, compared with the ApoE-/- mice (P = 0.01). Demand limb ischemia in the ApoE-/- phenotype exacerbated the expression of select systemic cytokines in plasma and blunted indices of muscle regeneration. Copyright © 2013 Elsevier Inc. All rights reserved.

Selective agonists of somatostatin receptor subtype 1 or 2 injected peripherally induce antihyperalgesic effect in two models of visceral hypersensitivity in mice

PubMed Central

Mulak, Agata; Larauche, Muriel; Biraud, Mandy; Million, Mulugeta; Rivier, Jean; Taché, Yvette

2014-01-01

Somatostatin interacts with 5 G-protein-coupled receptor (sst1–5). Octreotide, a stable sst2≫3≥5 agonist, octreotide, exerts a visceral anti-hyperalgesic effect in experimental and clinical studies. Little is known on the receptor subtypes involved. We investigated the influence of the stable sst1–5 agonist, ODT8-SST and selective receptor subtype peptide agonists (3 or 10 μg/mouse) injected intraperitoneally (ip) on visceral hypersensitivity in mice induced by repeated noxious colorectal distensions (4 sets of 3 CRD, each at 55 mmHg) or corticotropin-releasing factor receptor 1 agonist, cortagine given between 2 sets of graded CRD (15, 30, 45, and 60 mmHg, 3 times each pressure). The mean visceromotor response (VMR) was assessed using a non-invasive manometry method and values were expressed as percentage of the VMR to the 1st set of CRD baseline or to the 60 mmHg CRD, respectively. ODT8-SST (10 μg) and the sst2 agonist, S-346-011 (3 and 10 μg) prevented mechanically-induced visceral hypersensitivity in the 3 sets of CRD, the sst1 agonist (10 μg) blocked only the 2nd set and showed a trend at 3 μg while the sst4 agonist had no effect. The selective sst2 antagonist, S-406-028 blocked the sst2 agonist but not the sst1 agonist effect. The sst1 agonist (3 and 10 μg) prevented cortagine-induced hypersensitivity to CRD at each pressure while the sst2 agonist at 10 μg reduced it. These data indicate that in addition to sst2, the sst1 agonist may provide a novel promising target to alleviate visceral hypersensitivity induced by mechanoreceptor sensitization and more prominently, stress-related visceral nociceptive sensitization. PMID:25451334

Selective agonists of somatostatin receptor subtype 1 or 2 injected peripherally induce antihyperalgesic effect in two models of visceral hypersensitivity in mice.

PubMed

Mulak, Agata; Larauche, Muriel; Biraud, Mandy; Million, Mulugeta; Rivier, Jean; Taché, Yvette

2015-01-01

Somatostatin interacts with five G-protein-coupled receptor (sst1-5). Octreotide, a stable sst2≫3≥5 agonist, exerts a visceral anti-hyperalgesic effect in experimental and clinical studies. Little is known on the receptor subtypes involved. We investigated the influence of the stable sst1-5 agonist, ODT8-SST and selective receptor subtype peptide agonists (3 or 10μg/mouse) injected intraperitoneally (ip) on visceral hypersensitivity in mice induced by repeated noxious colorectal distensions (four sets of three CRD, each at 55mmHg) or corticotropin-releasing factor receptor 1 agonist, cortagine given between two sets of graded CRD (15, 30, 45, and 60mmHg, three times each pressure). The mean visceromotor response (VMR) was assessed using a non-invasive manometry method and values were expressed as percentage of the VMR to the 1st set of CRD baseline or to the 60mmHg CRD, respectively. ODT8-SST (10μg) and the sst2 agonist, S-346-011 (3 and 10μg) prevented mechanically induced visceral hypersensitivity in the three sets of CRD, the sst1 agonist (10μg) blocked only the 2nd set and showed a trend at 3μg while the sst4 agonist had no effect. The selective sst2 antagonist, S-406-028 blocked the sst2 agonist but not the sst1 agonist effect. The sst1 agonist (3 and 10μg) prevented cortagine-induced hypersensitivity to CRD at each pressure while the sst2 agonist at 10μg reduced it. These data indicate that in addition to sst2, the sst1 agonist may provide a novel promising target to alleviate visceral hypersensitivity induced by mechanoreceptor sensitization and more prominently, stress-related visceral nociceptive sensitization. Copyright © 2014 Elsevier Inc. All rights reserved.

Teaching Laura Kipnis&apos;s "Love&apos;s Labors" in "Ways of Reading"

ERIC Educational Resources Information Center

Fike, Matthew A.

2013-01-01

This essay describes a method of teaching a very challenging anthology piece: Laura Kipnis&apos;s "Love&apos;s Labors" (chapter 1 of her 2003 "Against Love: A Polemic"). The method, although designed for a critical thinking course, should also provide resources for those who teach Kipnis&apos;s work in writing courses. Using…

Differential Binding of Human ApoE Isoforms to Insulin Receptor is Associated with Aberrant Insulin Signaling in AD Brain Samples.

PubMed

Chan, Elizabeth S; Chen, Christopher; Soong, Tuck Wah; Wong, Boon-Seng

2018-03-01

Apolipoprotein E4 (ApoE4) is the strongest genetic risk factor for sporadic Alzheimer's disease (AD), where inheritance of this isoform predisposes development of AD in a gene dose-dependent manner. Although the mode of action of ApoE4 on AD onset and progression remains unknown, we have previously shown that ApoE4, and not ApoE3 expression, resulted in insulin signaling deficits in the presence of amyloid beta (Aβ). However, these reports were not conducted with clinical samples that more accurately reflect human disease. In this study, we investigated the effect of ApoE genotype on the insulin signaling pathway in control and AD human brain samples. We found that targets of the insulin signaling pathway were attenuated in AD cases, regardless of ApoE isoform. We also found a decrease in GluR1 subunit expression, and an increase NR2B subunit expression in AD cases, regardless of ApoE isoform. Lastly, we observed that more insulin receptor (IR) was immunoprecipitated in control cases, and more Aβ was immunoprecipitated with AD cases. But, when comparing among AD cases, we found that more IR was immunoprecipitated with ApoE3 than ApoE4, and more Aβ was immunoprecipitated with ApoE4 than ApoE3. Our results suggest that the difference in IR binding and effect on protein expression downstream of the IR may affect onset and progression of AD.

PF-06827443 Displays Robust Allosteric Agonist and Positive Allosteric Modulator Activity in High Receptor Reserve and Native Systems.

PubMed

Moran, Sean P; Cho, Hyekyung P; Maksymetz, James; Remke, Daniel H; Hanson, Ryan M; Niswender, Colleen M; Lindsley, Craig W; Rook, Jerri M; Conn, P Jeffrey

2018-04-25

Positive allosteric modulators (PAMs) of the M 1 subtype of muscarinic acetylcholine receptor have attracted intense interest as an exciting new approach for improving the cognitive deficits in schizophrenia and Alzheimer's disease. Recent evidence suggests that the presence of intrinsic agonist activity of some M 1 PAMs may reduce efficacy and contribute to adverse effect liability. However, the M 1 PAM PF-06827443 was reported to have only weak agonist activity at human M 1 receptors but produced M 1 -dependent adverse effects. We now report that PF-06827443 is an allosteric agonist in cell lines expressing rat, dog, and human M 1 and use of inducible cell lines shows that agonist activity of PF-06827443 is dependent on receptor reserve. Furthermore, PF-06827443 is an agonist in native tissue preparations and induces behavioral convulsions in mice similar to other ago-PAMs. These findings suggest that PF-06827443 is a robust ago-PAM, independent of species, in cell lines and native systems.

Structure-guided development of dual β2 adrenergic/dopamine D2 receptor agonists.

PubMed

Weichert, Dietmar; Stanek, Markus; Hübner, Harald; Gmeiner, Peter

2016-06-15

Aiming to discover dual-acting β2 adrenergic/dopamine D2 receptor ligands, a structure-guided approach for the evolution of GPCR agonists that address multiple targets was elaborated. Starting from GPCR crystal structures, we describe the design, synthesis and biological investigation of a defined set of compounds leading to the identification of the benzoxazinone (R)-3, which shows agonist properties at the adrenergic β2 receptor and substantial G protein-promoted activation at the D2 receptor. This directed approach yielded molecular probes with tuned dual activity. The congener desOH-3 devoid of the benzylic hydroxyl function was shown to be a β2 adrenergic antagonist/D2 receptor agonist with Ki values in the low nanomolar range. The compounds may serve as a promising starting point for the investigation and treatment of neurological disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

Potent and selective oxytocin receptor agonists without disulfide bridges.

PubMed

Adachi, Yusuke; Sakimura, Katsuya; Shimizu, Yuji; Nakayama, Masaharu; Terao, Yasuko; Yano, Takahiko; Asami, Taiji

2017-06-01

Oxytocin (OT) is a neuropeptide involved in a wide variety of physiological actions, both peripherally and centrally. Many human studies have revealed the potential of OT to treat autism spectrum disorders and schizophrenia. OT interacts with the OT receptor (OTR) as well as vasopressin 1a and 1b receptors (V 1a R, V 1b R) as an agonist, and agonistic activity for V 1a R and V 1b R may have a negative impact on the therapeutic effects of OTR agonism in the CNS. An OTR-selective agonistic peptide, FE 202767, in which the structural differences from OT are a sulfide bond instead of a disulfide bond, and N-alkylglycine replacement for Pro at position 7, was reported. However, the effects of amino acid substitutions in OT have not been comprehensively investigated to compare OTR, V 1a R, and V 1b R activities. This led us to obtain a new OTR-selective analog by comprehensive amino acid substitutions of OT and replacement of the disulfide bond. A systematic amino acid scanning (Ala, Leu, Phe, Ser, Glu, or Arg) of desamino OT (dOT) at positions 2, 3, 4, 5, 7, and 8 revealed the tolerability for the substitution at positions 7 and 8. Further detailed study showed that trans-4-hydroxyproline (trans-Hyp) at position 7 and γ-methylleucine [Leu(Me)] at position 8 were markedly effective for improving receptor selectivity without decreasing the potency at the OTR. Subsequently, a combination of these amino acid substitutions with the replacement of the disulfide bond of dOT analogs with a sulfide bond (carba analog) or an amide bond (lactam analog) yielded several promising analogs, including carba-1-[trans-Hyp 7 ,Leu(Me) 8 ]dOT (14) with a higher potency (7.2pM) at OTR than that of OT and marked selectivity (>10,000-fold) over V 1a R and V 1b R. Hence, we investigated comprehensive modification of OT and obtained new OT analogs that exhibited high potency at OTR with marked selectivity. These OTR-selective agonists could be useful to investigate OTR-mediated effects on

Partial agonists for α4β2 nicotinic receptors stimulate dopaminergic neuron firing with relatively enhanced maximal effects

PubMed Central

Chen, Ying; Broad, Lisa M; Phillips, Keith G; Zwart, Ruud

2012-01-01

BACKGROUND AND PURPOSE Partial agonists selective for α4β2 nicotinic ACh receptors have been developed for smoking cessation as they induce weak activation of native α4β2* receptors and inhibit effect of nicotine. However, it is unclear whether at brain functions there is an existence of receptor reserve that allows weak receptor activation to induce maximum physiological effects. We assessed the extent of α4β2 partial agonist-induced increase of firing rate in dopaminergic neurons and evaluated the influence of receptor reserve. EXPERIMENTAL APPROACH The relative maximal effects and potencies of six nicotinic agonists were assessed on recombinant human α4β2 and α7 receptors expressed in mammalian cell lines by measuring calcium influx. Agonist-induced increase of the spontaneous firing rate of dopaminergic neurons was recorded using microelectrodes in the ventral tegmental area of rat brain slices. KEY RESULTS All α4β2 partial and full agonists increased the firing rate concentration-dependently. Their sensitivity to subtype-selective antagonists showed predominant activation of native α4β2* receptors. However, partial agonists with relative maximal effects as low as 33% on α4β2 receptors maximally increased the firing rate and induced additional depolarization block of firing, demonstrating that partial activation of receptors caused the maximum increase in firing rate in the presence of a receptor reserve. CONCLUSIONS AND IMPLICATIONS Partial α4β2 agonists induced relatively enhanced effects on the firing rate of dopaminergic neurons, and the effect was mainly attributed to the existence of native α4β2* receptor reserve. The results have implications in the understanding of physiological effects and therapeutic efficacies of α4β2 partial agonists. PMID:21838750

Use of GnRH agonist implants for long-term suppression of fertility in extensively managed heifers and cows.

PubMed

D'Occhio, Michael J; Fordyce, Geoffry; Whyte, Tim R; Jubb, Tristan F; Fitzpatrick, Lee A; Cooper, Neil J; Aspden, William J; Bolam, Matt J; Trigg, Timothy E

2002-12-16

The ability of gonadotrophin releasing hormone (GnRH) agonist implants to suppress ovarian activity and prevent pregnancies, long-term, was examined in heifers and cows maintained under extensive management. At three cattle stations, heifers (2-year-old) and older cows (3- to 16-year-old) were assigned to a control group that received no treatment, or were treated with high-dose (12 mg, Station A) or low-dose (8 mg, Station B and Station C) GnRH agonist implants. The respective numbers of control and GnRH agonist-treated animals (heifers + cows) at each station were: Station A, 20 and 99; Station B, 19 and 89; Station C, 20 and 76. Animals were maintained with 4% bulls and monitored for pregnancy at 2-monthly intervals for approximately 12 months. Pregnancy rates for control heifers and control cows ranged from 60-90% and 80-100%, respectively, depending on the study site. The respective number of animals (heifers + cows) treated with GnRH agonist that conceived, and days to first conception, were: Station A, 9 (9%) and 336 +/- 3 days; Station B, 8 (10%) and 244 +/- 13 days; Station C, 20 (26%) and 231 +/- 3 days. Treatment with high-dose GnRH agonist prevented pregnancies for longer (approximately 300 days) than treatment with low-dose GnRH agonist (approximately 200 days). In the majority of heifers and cows treated with GnRH agonist, ovarian follicular growth was restricted to early antral follicles (2-4mm). The findings indicate that GnRH agonist implants have considerable potential as a practical technology to suppress ovarian activity and control reproduction in female cattle maintained in extensive rangelands environments. The technology also has broader applications in diverse cattle production systems. Copyright 2002 Elsevier Science B.V.

Definition of agonists and design of antagonists for alloreactive T cell clones using synthetic peptide libraries.

PubMed

de Koster, H S; Vermeulen, C J; Hiemstra, H S; Amons, R; Drijfhout, J W; Koning, F

1999-04-01

Alloreactive T cells form an important barrier for organ transplantation. To reduce the risk of rejection patients are given immunosuppressive drugs, which increase the chance of infection and the incidence of malignancies. It has been shown that a large proportion of alloreactive T cells specifically recognize peptides present in the groove of the allogeneic MHC molecule. This implies that it might be possible to modulate the alloresponse by peptides with antagonistic properties, thus preventing rejection without the side effects of general immunosuppression. Peptide antagonists can be designed on the basis of the original agonist, yet for alloreactive T cells these agonists are usually unknown. In this study we have used a dedicated synthetic peptide library to identify agonists for HLA-DR3-specific alloreactive T cell clones. Based on these agonists, altered peptide ligands (APL) were designed. Three APL could antagonize an alloreactive T cell clone in its response against the library-derived agonist as well as in its response against the original allodeterminant, HLA-DR3. This demonstrates that peptide libraries can be used to design antagonists for alloreactive T cells without knowledge about the nature of the actual allostimulatory peptide. Since the most potent agonists are selected, this strategy permits detection of potent antagonists. The results, however, also suggest that the degree of peptide dependency of alloreactive T cell clones may dictate whether a peptide antagonist can be found for such clones. Whether peptide antagonists will be valuable in the development of donor-patient-specific immunosuppression may therefore depend on the specificity of the in vivo-generated alloreactive T cells.

A Potent and Site-Selective Agonist of TRPA1.

PubMed

Takaya, Junichiro; Mio, Kazuhiro; Shiraishi, Takuya; Kurokawa, Tatsuki; Otsuka, Shinya; Mori, Yasuo; Uesugi, Motonari

2015-12-23

TRPA1 is a member of the transient receptor potential (TRP) cation channel family that is expressed primarily on sensory neurons. This chemosensor is activated through covalent modification of multiple cysteine residues with a wide range of reactive compounds including allyl isothiocyanate (AITC), a spicy component of wasabi. The present study reports on potent and selective agonists of TRPA1, discovered through screening 1657 electrophilic molecules. In an effort to validate the mode of action of hit molecules, we noted a new TRPA1-selective agonist, JT010 (molecule 1), which opens the TRPA1 channel by covalently and site-selectively binding to Cys621 (EC50 = 0.65 nM). The results suggest that a single modification of Cys621 is sufficient to open the TRPA1 channel. The TRPA1-selective probe described herein might be useful for further mechanistic studies of TRPA1 activation.

Calculus Students&apos; and Instructors&apos; Conceptualizations of Slope: A Comparison across Academic Levels

ERIC Educational Resources Information Center

Nagle, Courtney; Moore-Russo, Deborah; Viglietti, Janine; Martin, Kristi

2013-01-01

This study considers tertiary calculus students&apos; and instructors&apos; conceptualizations of slope. Qualitative techniques were employed to classify responses to 5 items using conceptualizations of slope identified across various research settings. Students&apos; responses suggest that they rely on procedurally based conceptualizations of…

The cathelicidin protein CRAMP is a potential atherosclerosis self-antigen in ApoE(-/-) mice

PubMed Central

Mihailovic, Peter M.; Lio, Wai Man; Yano, Juliana; Zhao, Xiaoning; Zhou, Jianchang; Chyu, Kuang-Yuh; Shah, Prediman K.; Cercek, Bojan

2017-01-01

Auto-immunity is believed to contribute to inflammation in atherosclerosis. The antimicrobial peptide LL-37, a fragment of the cathelicidin protein precursor hCAP18, was previously identified as an autoantigen in psoriasis. Given the reported link between psoriasis and coronary artery disease, the biological relevance of the autoantigen to atherosclerosis was tested in vitro using a truncated (t) form of the mouse homolog of hCAP18, CRAMP, on splenocytes from athero-prone ApoE(-/-) mice. Stimulation with tCRAMP resulted in increased CD8+ T cells with Central Memory and Effector Memory phenotypes in ApoE(-/-) mice, differentially activated by feeding with normal chow or high fat diet. Immunization of ApoE(-/-) with different doses of the shortened peptide (Cramp) resulted in differential outcomes with a lower dose reducing atherosclerosis whereas a higher dose exacerbating the disease with increased neutrophil infiltration of the atherosclerotic plaques. Low dose Cramp immunization also resulted in increased splenic CD8+ T cell degranulation and reduced CD11b+CD11c+ conventional dendritic cells (cDCs), whereas high dose increased CD11b+CD11c+ cDCs. Our results identified CRAMP, the mouse homolog of hCAP-18, as a potential self-antigen involved in the immune response to atherosclerosis in the ApoE(-/-) mouse model. PMID:29091929

The four As associated with pathological Parkinson disease gamblers: anxiety, anger, age, and agonists

PubMed Central

Shapiro, Michael A; Chang, Yu Ling; Munson, Sarah K; Jacobson, Charles E; Rodriguez, Ramon L; Skidmore, Frank M; Okun, Michael S; Fernandez, Hubert H

2007-01-01

Several studies have related pathological gambling in PD to dopamine agonist therapy. A mail-in survey was sent to PD patients seen at the University of Florida Movement Disorders Center to determine gambling frequency and behavior, and any lifestyle or environmental factors associated with compulsive gambling in PD. 462 surveys were sent and 127 completed surveys were returned, of which ten were from patients who met criteria for compulsive gambling. All ten were taking dopamine agonists coincident with the compulsive gambling. Compulsive gamblers were younger, and psychological distress measures revealed that compulsive gamblers exhibited higher levels of anxiety, anger, and confusion. Thus in this cohort, we have uncovered the several characteristics of the most likely PD compulsive gambler, namely: (young) age, “angry”, “anxious”, and using a (dopamine) agonist. PMID:19300546

The four As associated with pathological Parkinson disease gamblers: anxiety, anger, age, and agonists.

PubMed

Shapiro, Michael A; Chang, Yu Ling; Munson, Sarah K; Jacobson, Charles E; Rodriguez, Ramon L; Skidmore, Frank M; Okun, Michael S; Fernandez, Hubert H

2007-02-01

Several studies have related pathological gambling in PD to dopamine agonist therapy. A mail-in survey was sent to PD patients seen at the University of Florida Movement Disorders Center to determine gambling frequency and behavior, and any lifestyle or environmental factors associated with compulsive gambling in PD. 462 surveys were sent and 127 completed surveys were returned, of which ten were from patients who met criteria for compulsive gambling. All ten were taking dopamine agonists coincident with the compulsive gambling. Compulsive gamblers were younger, and psychological distress measures revealed that compulsive gamblers exhibited higher levels of anxiety, anger, and confusion. Thus in this cohort, we have uncovered the several characteristics of the most likely PD compulsive gambler, namely: (young) age, "angry", "anxious", and using a (dopamine) agonist.

Smooth muscle cells in atherosclerosis originate from the local vessel wall and not circulating progenitor cells in ApoE knockout mice.

PubMed

Bentzon, Jacob F; Weile, Charlotte; Sondergaard, Claus S; Hindkjaer, Johnny; Kassem, Moustapha; Falk, Erling

2006-12-01

Recent studies of bone marrow (BM)-transplanted apoE knockout (apoE-/-) mice have concluded that a substantial fraction of smooth muscle cells (SMCs) in atherosclerosis arise from circulating progenitor cells of hematopoietic origin. This pathway, however, remains controversial. In the present study, we reexamined the origin of plaque SMCs in apoE-/- mice by a series of BM transplantations and in a novel model of atherosclerosis induced in surgically transferred arterial segments. We analyzed plaques in lethally irradiated apoE-/- mice reconstituted with sex-mismatched BM cells from eGFP+ apoE-/- mice, which ubiquitously express enhanced green fluorescent protein (eGFP), but did not find a single SMC of donor BM origin among approximately 10,000 SMC profiles analyzed. We then transplanted arterial segments between eGFP+ apoE-/- and apoE-/- mice (isotransplantation except for the eGFP transgene) and induced atherosclerosis focally within the graft by a recently invented collar technique. No eGFP+ SMCs were found in plaques that developed in apoE-/- artery segments grafted into eGFP+ apoE-/- mice. Concordantly, 96% of SMCs were eGFP+ in plaques induced in eGFP+ apoE-/- artery segments grafted into apoE-/- mice. These experiments show that SMCs in atherosclerotic plaques are exclusively derived from the local vessel wall in apoE-/- mice.

Toll-Like Receptor–2/6 and Toll-Like Receptor–9 Agonists Suppress Viral Replication but Not Airway Hyperreactivity in Guinea Pigs

PubMed Central

Evans, Scott E.; Dickey, Burton F.; Fryer, Allison D.; Jacoby, David B.

2013-01-01

Respiratory virus infections cause airway hyperreactivity (AHR). Preventative strategies for virus-induced AHR remain limited. Toll-like receptors (TLRs) have been suggested as a therapeutic target because of their central role in triggering antiviral immune responses. Previous studies showed that concurrent treatment with TLR2/6 and TLR9 agonists reduced lethality and the microbial burden in murine models of bacterial and viral pneumonia. This study investigated the effects of TLR2/6 and TLR9 agonist pretreatment on parainfluenza virus pneumonia and virus-induced AHR in guinea pigs in vivo. Synthetic TLR2/6 lipopeptide agonist Pam2CSK4 and Class C oligodeoxynucleotide TLR9 agonist ODN2395, administered in combination 24 hours before virus infection, significantly reduced viral replication in the lung. Despite a fivefold reduction in viral titers, concurrent TLR2/6 and TLR9 agonist pretreatment did not prevent virus-induced AHR or virus-induced inhibitory M2 muscarinic receptor dysfunction. Interestingly, the TLR agonists independently caused non–M2-dependent AHR. These data confirm the therapeutic antiviral potential of TLR agonists, while suggesting that virus inhibition may be insufficient to prevent virus-induced airway pathophysiology. Furthermore, TLR agonists independently cause AHR, albeit through a distinctly different mechanism from that of parainfluenza virus. PMID:23449736

Suppression of atherosclerosis by synthetic REV-ERB agonist

PubMed Central

Sitaula, Sadichha; Billon, Cyrielle; Kamenecka, Theodore M.; Solt, Laura A.; Burris, Thomas P.

2015-01-01

The nuclear receptors for heme, REV-ERBα and REV-ERBβ, play important roles in the regulation of metabolism and inflammation. Recently it was demonstrated that reduced REV-ERBα expression in hematopoetic cells in LDL receptor null mice led to increased atherosclerosis. We sought to determine if synthetic REV-ERB agonists that we have developed might have the ability to suppress atherosclerosis in this model. A previously characterized synthetic REV-ERB agonist, SR9009, was used to determine if activation of REV-ERB activity would affect atherosclerosis in LDL receptor deficient mice. Atherosclerotic plaque size was significantly reduced (p < 0.05) in mice administered SR9009 (100 mg/kg) for seven weeks compared to control mice (n = 10 per group). SR9009 treatment of bone marrow-derived mouse macrophages (BMDM) reduced the polarization of BMDMs to proinflammatory M1 macrophage while increasing the polarization of BMDMs to anti-inflammatory M2 macrophages. Our results suggest that pharmacological targeting of REV-ERBs may be a viable therapeutic option for treatment of atherosclerosis. PMID:25800870

Identification of Buctopamine and Mebuctopamine, a β2 Receptor Agonist and Its Metabolite, in Swine Hair and Feed Additives.

PubMed

Chen, Ying-Heng; Yang, Chia-Ying; Cheng, Chih Wen; Lin, Yi-Ying; Kuo, Su Lien; Hsin, Ling-Wei

2017-05-17

4-[2-(t-Butylamino)-1-hydroxyethyl]phenol (buctopamine, 4), a new β 2 receptor agonist (β 2 -agonist), was found to be an adulterant in feed additives for swine in Taiwan, where using β 2 -agonists in food-production animals is prohibited. Buctopamine and its metabolite, 4-[2-(t-butylamino)-1-hydroxyethyl]-2-methoxyphenol (mebuctopamine, 2), were detected in swine hair specimens. Authentic compounds 2 and 4 were synthesized with 98.6% and 97.7% purity, respectively, as reference standards for analysis, and both compounds were more hydrophilic than ractopamine and clenbuterol. In a preliminary pharmacological evaluation, compounds 2 and 4 exhibited moderate human β 2 receptor binding affinity and did not show significant affinities for the human α 1 , α 2 , β 1 , and β 3 receptors. After addition of compounds 2-4 into the β 2 -agonist library, a multiresidue analysis of 26 β 2 -agonists by using triple quadrupole LC/MS/MS for routine screening conducted by regulatory authorities was established, in which the common limits of quantification for the 26 β 2 -agonists in swine feed and hair are 10 and 25 ng/g, respectively. In addition, the illegal use of buctopamine (4) has been effectively prevented. The results of this study are also useful for controlling the illegal use of new β 2 -agonists in food-production animals.

Nitric oxide donor beta2-agonists: furoxan derivatives containing the fenoterol moiety and related furazans.

PubMed

Buonsanti, M Federica; Bertinaria, Massimo; Stilo, Antonella Di; Cena, Clara; Fruttero, Roberta; Gasco, Alberto

2007-10-04

The structure of fenoterol, a beta2-adrenoceptor agonist used in therapy, has been joined with furoxan NO-donor moieties to give new NO-donor beta2-agonists. The furazan analogues, devoid of the property to release NO, were also synthesized for comparison. All the compounds retained beta2-agonistic activity at micromolar or submicromolar concentration when tested on guinea pig tracheal rings precontracted with carbachol. Among the furoxan derivatives, the NO contribution to trachea relaxation was evident with product 15b at micromolar concentrations. All the new NO-donor hybrids were able to dilate rat aortic strips precontracted with phenylephrine. Both furoxan and furazan derivatives displayed antioxidant activity greater than that of fenoterol.

Effects of kappa opioid agonists alone and in combination with cocaine on heart rate and blood pressure in conscious squirrel monkeys.

PubMed

Schindler, Charles W; Graczyk, Zofi; Gilman, Joanne P; Negus, S Stevens; Bergman, Jack; Mello, Nancy K; Goldberg, Steven R

2007-12-08

As kappa agonists have been proposed as treatments for cocaine abuse, the cardiovascular effects of the kappa opioid receptor agonists ethylketocyclazocine (EKC) and enadoline were investigated in conscious squirrel monkeys. Both EKC and enadoline increased heart rate with little effect on blood pressure. This effect appeared to be specific for kappa receptors as the mu opioid agonist morphine did not mimic the effects of the kappa agonists. The opioid antagonist naltrexone, at a dose of 1.0 mg/kg, blocked the effect of EKC. An action at both central and peripheral receptors may be responsible for the heart rate increase following kappa agonist treatment. The ganglionic blocker chlorisondamine partially antagonized the effect of EKC on heart rate, suggesting central involvement, while the peripherally-acting agonist ICI 204,448 ((+/-)-1-[2,3- (Dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride) also increased heart rate, supporting a peripheral site of action. When given in combination with cocaine, EKC produced effects that were sub-additive, suggesting that the kappa agonists may be used safely as cocaine abuse treatments.

Characterization and expression of amphioxus ApoD gene encoding an archetype of vertebrate ApoD proteins.

PubMed

Wang, Lei; Zhang, Shicui; Liu, Zhenhui; Li, Hongyan; Wang, Yongjun; Jiang, Shengjuan

2007-01-01

Here we report a homologue of the apolipoprotein D gene (AmphiApoD) in amphioxus, Branchiostoma belcheri tsingtauense, the first such finding in a basal chordate cephalochordate. The main features of the protein predicted from AmphiApoD are characteristic of the apolipoprotein D. Phylogenetic analysis places AmphiApoD at the base of the phylogenetic tree, suggesting that AmphiApoD is the archetype of the vertebrate ApoD genes. Both whole mount in situ hybridization and Northern blotting and RT-PCR as well as in situ hybridization histochemistry reveal that AmphiApoD is expressed in tissues derived from mesoderm and endoderm including notochord and hind-gut, which contrasts with the strong expression patterns of ApoD genes in the ectodermal derivatives in mammals and birds. The expression profiles of the ApoD gene may have been changed to be expressed in the endo-mesodermal derivatives in amphioxus after the vertebrate and cephalochordate lineages diverged; alternatively, the ApoD gene may first have been expressed in the endo-mesoderm during embryogenesis in the last common ancestor of all chordates, and subsequently came to be expressed in the ectodermal derivatives of vertebrates including mammals and birds.

ApoA-I/A-II-HDL positively associates with apoB-lipoproteins as a potential atherogenic indicator.

PubMed

Kido, Toshimi; Kondo, Kazuo; Kurata, Hideaki; Fujiwara, Yoko; Urata, Takeyoshi; Itakura, Hiroshige; Yokoyama, Shinji

2017-11-29

We recently reported distinct nature of high-density lipoproteins (HDL) subgroup particles with apolipoprotein (apo) A-I but not apoA-II (LpAI) and HDL having both (LpAI:AII) based on the data from 314 Japanese. While plasma HDL level almost exclusively depends on concentration of LpAI having 3 to 4 apoA-I molecules, LpAI:AII appeared with almost constant concentration regardless of plasma HDL levels having stable structure with two apoA-I and one disulfide-dimeric apoA-II molecules (Sci. Rep. 6; 31,532, 2016). The aim of this study is further characterization of LpAI:AII with respect to its role in atherogenesis. Association of LpAI, LpAI:AII and other HDL parameters with apoB-lipoprotein parameters was analyzed among the cohort data above. ApoA-I in LpAI negatively correlated with the apoB-lipoprotein parameters such as apoB, triglyceride, nonHDL-cholesterol, and nonHDL-cholesterol + triglyceride, which are apparently reflected in the relations of the total HDL parameters to apoB-lipoproteins. In contrast, apoA-I in LpAI:AII and apoA-II positively correlated to the apoB-lipoprotein parameters even within their small range of variation. These relationships are independent of sex, but may slightly be influenced by the activity-related CETP mutations. The study suggested that LpAI:AII is an atherogenic indicator rather than antiatherogenic. These sub-fractions of HDL are to be evaluated separately for estimating atherogenic risk of the patients.

Long-Acting β2-Agonists in Asthma: Enantioselective Safety Studies are Needed.

PubMed

Jacobson, Glenn A; Raidal, Sharanne; Hostrup, Morten; Calzetta, Luigino; Wood-Baker, Richard; Farber, Mark O; Page, Clive P; Walters, E Haydn

2018-05-01

Long-acting β2-agonists (LABAs) such as formoterol and salmeterol are used for prolonged bronchodilatation in asthma, usually in combination with inhaled corticosteroids (ICSs). Unexplained paradoxical asthma exacerbations and deaths have been associated with LABAs, particularly when used without ICS. LABAs clearly demonstrate effective bronchodilatation and steroid-sparing activity, but long-term treatment can lead to tolerance of their bronchodilator effects. There are also concerns with regard to the effects of LABAs on bronchial hyperresponsiveness (BHR), where long-term use is associated with increased BHR and loss of bronchoprotection. A complicating factor is that formoterol and salmeterol are both chiral compounds, usually administered as 50:50 racemic (rac-) mixtures of two enantiomers. The chiral nature of these compounds has been largely forgotten in the debate regarding LABA safety and effects on BHR, particularly that (S)-enantiomers of β2-agonists may be deleterious to asthma control. LABAs display enantioselective pharmacokinetics and pharmacodynamics. Biological plausibility of the deleterious effects of β2-agonists (S)-enantiomers is provided by in vitro and in vivo studies from the short-acting β2-agonist (SABA) salbutamol. Supportive clinical findings include the fact that patients in emergency departments who demonstrate a blunted response to salbutamol are more likely to benefit from (R)-salbutamol than rac-salbutamol, and resistance to salbutamol appears to be a contributory mechanism in rapid asthma deaths. More effort should therefore be applied to investigating potential enantiospecific effects of LABAs on safety, specifically bronchoprotection. Safety studies directly assessing the effects of LABA (S)-enantiomers on BHR are long overdue.

Therapeutic Potential of 5-HT2C Receptor Agonists for Addictive Disorders.

PubMed

Higgins, Guy A; Fletcher, Paul J

2015-07-15

The neurotransmitter 5-hydroxytryptamine (5-HT; serotonin) has long been associated with the control of a variety of motivated behaviors, including feeding. Much of the evidence linking 5-HT and feeding behavior was obtained from studies of the effects of the 5-HT releaser (dex)fenfluramine in laboratory animals and humans. Recently, the selective 5-HT2C receptor agonist lorcaserin received FDA approval for the treatment of obesity. This review examines evidence to support the use of selective 5-HT2C receptor agonists as treatments for conditions beyond obesity, including substance abuse (particularly nicotine, psychostimulant, and alcohol dependence), obsessive compulsive, and excessive gambling disorder. Following a brief survey of the early literature supporting a role for 5-HT in modulating food and drug reinforcement, we propose that intrinsic differences between SSRI and serotonin releasers may have underestimated the value of serotonin-based pharmacotherapeutics to treat clinical forms of addictive behavior beyond obesity. We then highlight the critical involvement of the 5-HT2C receptor in mediating the effect of (dex)fenfluramine on feeding and body weight gain and the evidence that 5-HT2C receptor agonists reduce measures of drug reward and impulsivity. A recent report of lorcaserin efficacy in a smoking cessation trial further strengthens the idea that 5-HT2C receptor agonists may have potential as a treatment for addiction. This review was prepared as a contribution to the proceedings of the 11th International Society for Serotonin Research Meeting held in Hermanus, South Africa, July 9-12, 2014.

Muscarinic and nicotinic acetylcholine receptor agonists: current scenario in Alzheimer's disease therapy.

PubMed

Verma, Stuti; Kumar, Ashwini; Tripathi, Timir; Kumar, Awanish

2018-04-16

Alzheimer's disease (AD) has become the primary cause of dementia. It shows a progressive cognitive dysfunction with degenerating neurons. Acetylcholine receptors (AChRs) propagate the cognitive ability and it consists of two primary members namely muscarinic (mAChRs) and nicotinic receptors (nAChRs). Where mAChRs is G-protein coupled receptor, (nAChRs) are ligand-gated ion channels. The conventional therapeutic regimen for AD consists of three acetylcholinestearse inhibitors while a single NMDA receptor antagonist. Researchers around the globe are developing new and modifying the existing AChRs agonists to develop lead candidates with lower risk to benefit ratio where benefits clearly outweigh the adverse events. We have searched PubMed, MEDLINE, Google scholar, Science Direct and, Web of Science with keywords "Muscarinic/Nicotinic acetylcholine receptor, agonists and, AD". The literature search included articles written in English. Scientific relevance for clinical studies, basic science studies is eligibility criteria for articles referred in this paper. M1 is the primary muscarinic subtype while α7 is the primary nAChR subtype that is responsible for cognition and memory and these two have been the major recent experimental targets for mAChR agonist strategy. The last cholinergic receptor agonist to enter phase 3 trial was EVP-6124 (Enceniclin) but was withdrawn due to severe gastrointestinal adverse effects. We aim to present an overview of the efforts and achievements in targeting Muscarinic and Nicotinic acetylcholine receptor in the current review for development of better AD therapeutics. © 2018 Royal Pharmaceutical Society.

Extension&apos;s Role in Developing a Farmers&apos; Market

ERIC Educational Resources Information Center

Civittolo, David

2012-01-01

Interest in access to local food is increasing. Communities of all types and sizes have volunteers interested in creating farmers&apos; markets. Extension can play an important role in the development of farmers&apos; markets because it is ideally suited to organize and coordinate these volunteer energies. By helping community volunteers focus…

Gingerols: a novel class of vanilloid receptor (VR1) agonists

PubMed Central

Dedov, Vadim N; Tran, Van H; Duke, Colin C; Connor, Mark; Christie, MacDonald J; Mandadi, Sravan; Roufogalis, Basil D

2002-01-01

Gingerols, the pungent constituents of ginger, were synthesized and assessed as agonists of the capsaicin-activated VR1 (vanilloid) receptor. [6]-Gingerol and [8]-gingerol evoked capsaicin-like intracellular Ca2+ transients and ion currents in cultured DRG neurones. These effects of gingerols were blocked by capsazepine, the VR1 receptor antagonist. The potency of gingerols increased with increasing size of the side chain and with the overall hydrophobicity in the series. We conclude that gingerols represent a novel class of naturally occurring VR1 receptor agonists that may contribute to the medicinal properties of ginger, which have been known for centuries. The gingerol structure may be used as a template for the development of drugs acting as moderately potent activators of the VR1 receptor. PMID:12411409

The opioid receptor triple agonist DPI-125 produces analgesia with less respiratory depression and reduced abuse liability.

PubMed

Yi, Shou-Pu; Kong, Qing-Hong; Li, Yu-Lei; Pan, Chen-Ling; Yu, Jie; Cui, Ben-Qiang; Wang, Ying-Fei; Wang, Guan-Lin; Zhou, Pei-Lan; Wang, Li-Li; Gong, Ze-Hui; Su, Rui-Bin; Shen, Yue-Hai; Yu, Gang; Chang, Kwen-Jen

2017-07-01

Opioid analgesics remain the first choice for the treatment of moderate to severe pain, but they are also notorious for their respiratory depression and addictive effects. This study focused on the pharmacology of a novel opioid receptor mixed agonist DPI-125 and attempted to elucidate the relationship between the δ-, μ- and κ-receptor potency ratio and respiratory depression and abuse liability. Five diarylmethylpiperazine compounds (DPI-125, DPI-3290, DPI-130, KUST202 and KUST13T02) were selected for this study. PKA fluorescence redistribution assays in CHO cells individually expressing δ-, μ- or κ-receptors were used to measure the agonist potency. The respiratory safety profiles were estimated in rats by the ratio of ED 50 (pCO 2 increase)/ED 50 (antinociception). The abuse liability of DPI-125 was evaluated with a self-administration model in rhesus monkeys. The observed agonist potencies of DPI-125 for δ-, μ- and κ-opioid receptors were 4.29±0.36, 11.10±3.04, and 16.57±4.14 nmol/L, respectively. The other four compounds were also mixed agonists with varying potencies. DPI-125 exhibited a high respiratory safety profile, clearly related to its high δ-receptor potency. The ratio of the EC 50 potencies for the μ- and δ-receptors was found to be positively correlated with the respiratory safety ratio. DPI-125 has similar potencies for μ- and κ-receptors, which is likely the reason for its reduced abuse potential. Our results demonstrate that the opioid receptor mixed agonist DPI-125 is safer and less addictive than traditional μ-agonist analgesics. These findings suggest that the development of δ>μ∼κ opioid receptor mixed agonists is feasible, and such compounds could represent a promising class of potent analgesics with wider therapeutic windows.

5-HT4 receptor agonists enhance both cholinergic and nitrergic activities in human isolated colon circular muscle.

PubMed

Cellek, S; John, A K; Thangiah, R; Dass, N B; Bassil, A K; Jarvie, E M; Lalude, O; Vivekanandan, S; Sanger, G J

2006-09-01

Previous studies have demonstrated mixed inhibitory and facilitatory effects of 5-hydroxytryptamine-4 (5-HT(4)) receptor agonists on electrical field stimulation (EFS)-induced responses in human isolated colon. Here we report three types of responses to EFS in human isolated colon circular muscle: monophasic cholinergic contraction during EFS, biphasic response (nitrergic relaxation during EFS followed by cholinergic contraction after termination of EFS) and triphasic response (cholinergic contraction followed by nitrergic relaxation during EFS and a tachykininergic contraction after EFS). The effects of two 5-HT(4) receptor agonists, prucalopride and tegaserod were then investigated on monophasic responses only. Each compound inhibited contractions during EFS in a concentration-dependent manner. In the presence of N(omega)-nitro-l-arginine methyl ester (l-NAME) however, prucalopride and tegaserod enhanced the contractions in a concentration-dependent manner. In strips where the tone was elevated with substance-P and treated with scopolamine, EFS-induced relaxations were enhanced by the two agonists. The above observed effects by the two agonists were abolished by 5-HT(4) receptor antagonist SB-204070. The two agonists did not alter the tone raised by substance-P in the presence of scopolamine and l-NAME and did not affect carbachol-induced contractions in the presence of tetrodotoxin. These results suggest that in the circular muscle of human colon, 5-HT(4) receptor agonists simultaneously facilitate the activity of neurones which release the inhibitory and excitatory neurotransmitters, nitric oxide and acetylcholine respectively.

Transcriptional Modulation of the Immune Response by Peroxisome Proliferator-Activated Receptor-α Agonists in Autoimmune Disease1

PubMed Central

Gocke, Anne R.; Hussain, Rehana Z.; Yang, Yuhong; Peng, Haiyan; Weiner, Jeffrey; Ben, Li-Hong; Drew, Paul D.; Stuve, Olaf; Lovett-Racke, Amy E.; Racke, Michael K.

2010-01-01

Peroxisome proliferator-activated receptor-α (PPARα) agonists have been shown to have a therapeutic benefit in experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis (MS). In this study, we investigated the mechanism by which the PPARα agonist gemfibrozil induces immune deviation and protects mice from EAE. We demonstrated that treatment with gemfibrozil increases expression of the Th2 transcription factor GATA-3 and decreases expression of the Th1 transcription factor T-bet in vitro and directly ex vivo. These changes correlated with an increase in nuclear PPARα expression. Moreover, the protective effects of PPARα agonists in EAE were shown to be partially dependent on IL-4 and to occur in a receptor-dependent manner. PPARα was demonstrated, for the first time, to regulate the IL-4 and IL-5 genes and to bind the IL-4 promoter in the presence of steroid receptor coactivator-1, indicating that PPARα can directly transactivate the IL-4 gene. Finally, therapeutic administration of PPARα agonists ameliorated clinically established EAE, suggesting that PPARα agonists may provide a treatment option for immune-mediated inflammatory diseases. PMID:19299749

Ovariectomy modify local renin-angiotensin-aldosterone system gene expressions in the heart of ApoE (-/-) mice.