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Sample records for 5-ht2a receptor density

  1. 5-HT2A Serotonin Receptor Density in Adult Male Rats’ Hippocampus after Morphine-based Conditioned Place Preference

    PubMed Central

    Mohammadi, Rabie; Jahanshahi, Mehrdad; Jameie, Seyed Behnamedin

    2016-01-01

    Introduction: A close interaction exists between the brain opioid and serotonin (5-HT) neurotransmitter systems. Brain neurotransmitter 5-HT plays an important role in the regulation of reward-related processing. However, a few studies have investigated the potential role of 5-HT2A receptors in this behavior. Therefore, the aim of the present study was to assess the influence of morphine and Conditioned Place Preference (CPP) on the density of 5-HT2A receptor in neurons of rat hippocampal formation. Methods: Morphine (10 mg/kg, IP) was injected in male Wistar rats for 7 consecutive days (intervention group), but control rats received just normal saline (1 mL/kg, IP). We used a hotplate test of analgesia to assess induction of tolerance to analgesic effects of morphine on days 1 and 8 of injections. Later, two groups of rats were sacrificed one day after 7 days of injections, their whole brains removed, and the striatum and PFC immediately dissected. Then, the NR1 gene expression was examined with a semi-quantitative RT-PCR method. Results: Our data showed that the maximum response was obtained with 2.5 mg/kg of morphine. The density of 5-HT2A receptor in different areas of the hippocampus increased significantly at sham-morphine and CPP groups (P<0.05). On the other hand, the CPP groups had more 5-HT2A receptors than sham-morphine groups and also the sham-morphine groups had more 5-HT2A receptors than the control groups. Conclusion: We concluded that the phenomenon of conditioned place preference induced by morphine can cause a significant increase in the number of serotonin 5-HT2A receptors in neurons of all areas of hippocampus. PMID:27563418

  2. INSIGHTS INTO THE REGULATION OF 5-HT2A RECEPTORS BY SCAFFOLDING PROTEINS AND KINASES

    PubMed Central

    Allen, John A.; Yadav, Prem N.

    2008-01-01

    SUMMARY 5-HT2A serotonin receptors are essential molecular targets for the actions of LSD-like hallucinogens and atypical antipsychotic drugs. 5-HT2A serotonin receptors also mediate a variety of physiological processes in peripheral and central nervous systems including platelet aggregation, smooth muscle contraction, and the modulation of mood and perception. Scaffolding proteins have emerged as important regulators of 5-HT2A receptors and our recent studies suggest multiple scaffolds exist for 5-HT2A receptors including PSD95, arrestin, and caveolin. In addition, a novel interaction has emerged between p90 ribosomal S6 kinase and 5-HT2A receptors which attenuates receptor signaling. This article reviews our recent studies and emphasizes the role of scaffolding proteins and kinases in the regulation of 5-HT2A trafficking, targeting and signaling. PMID:18640136

  3. Evaluation of structural effects on 5-HT2A receptor antagonism by aporphines: identification of a new aporphine with 5-HT2A antagonist activity

    PubMed Central

    Ponnala, Shashikanth; Gonzales, Junior; Kapadia, Nirav; Navarro, Hernan A.; Harding, Wayne W.

    2014-01-01

    A set of aporphine analogs related to nantenine was evaluated for antagonist activity at 5-HT2A and α1A adrenergic receptors. With regards to 5-HT2A receptor antagonism, a C2 allyl group is detrimental to activity. The chiral center of nantenine is not important for 5-HT2A antagonist activity, however the N6 nitrogen atom is a critical feature for 5-HT2A antagonism. Compound 12b was the most potent 5-HT2A aporphine antagonist identified in this study and has similar potency to previously identified aporphine antagonists 2 and 3. The ring A and N6 modifications examined were detrimental to α1A antagonism. A slight eutomeric preference for the R enantiomer of nantenine was observed in relation to α1A antagonism. PMID:24630561

  4. Increased hypothalamic 5-HT2A receptor gene expression and effects of pharmacologic 5-HT2A receptor inactivation in obese A{sup y} mice

    SciTech Connect

    Nonogaki, Katsunori . E-mail: knonogaki-tky@umin.ac.jp; Nozue, Kana; Oka, Yoshitomo

    2006-12-29

    Serotonin (5-hydroxytryptamine; 5-HT) 2A receptors contribute to the effects of 5-HT on platelet aggregation and vascular smooth muscle cell proliferation, and are reportedly involved in decreases in plasma levels of adiponectin, an adipokine, in diabetic subjects. Here, we report that systemic administration of sarpogrelate, a 5-HT2A receptor antagonist, suppressed appetite and increased hypothalamic pro-opiomelanocortin and cocaine- and amphetamine-regulated transcript, corticotropin releasing hormone, 5-HT2C, and 5-HT1B receptor gene expression. A{sup y} mice, which have ectopic expression of the agouti protein, significantly increased hypothalamic 5-HT2A receptor gene expression in association with obesity compared with wild-type mice matched for age. Systemic administration of sarpogrelate suppressed overfeeding, body weight gain, and hyperglycemia in obese A{sup y} mice, whereas it did not increase plasma adiponectin levels. These results suggest that obesity increases hypothalamic 5-HT2A receptor gene expression, and pharmacologic inactivation of 5-HT2A receptors inhibits overfeeding and obesity in A{sup y} mice, but did not increase plasma adiponectin levels.

  5. Activated astrocytes display increased 5-HT2a receptor expression in pathological states.

    PubMed

    Wu, C; Singh, S K; Dias, P; Kumar, S; Mann, D M

    1999-08-01

    In human brain tissues from patients dying with cerebral infarction, hypertensive encephalopathy, Alzheimer's disease, Huntington's disease, frontotemporal dementia, and Creutzfeldt-Jakob disease there is an activation of astrocytes. Such activated astrocytes display GFAP and strong 5-HT(2A), but not 5-HT(2B) or 5-HT(2C), receptor immunoreactivity; this 5-HT(2A) reaction has not been observed in normal, nonactivated astrocytes. It is suggested that an up-regulation of 5-HT(2A) receptors may be part of an early response reaction in astrocytes, possibly designed to maintain homeostasis or to induce secondary message pathways involving trophic factors or glycogenolysis. PMID:10415157

  6. Expression of serotonin 5-HT(2A) receptors in the human cerebellum and alterations in schizophrenia.

    PubMed

    Eastwood, S L; Burnet, P W; Gittins, R; Baker, K; Harrison, P J

    2001-11-01

    The occurrence of human cerebellar serotonin 5-HT(2A) receptors (5-HT(2A)R) is equivocal and their status in schizophrenia unknown. Using a range of techniques, we investigated cerebellar 5-HT(2A)R expression in 16 healthy subjects and 16 subjects with schizophrenia. Immunocytochemistry with a monoclonal antibody showed labelling of Purkinje cell bodies and dendrites, as well as putative astrocytes. Western blots showed a major band at approximately 45 kDa. Receptor autoradiography and homogenate binding with [(3)H]ketanserin revealed cerebellar 5-HT(2A)R binding sites present at levels approximately a third of that in prefrontal cortex. 5-HT(2A)R mRNA was detected by reverse transcriptase-polymerase chain reaction, with higher relative levels in men than women. Several aspects of 5-HT(2A)R expression were altered in schizophrenia. 5-HT(2A)R immunoreactivity in Purkinje cells was partially redistributed from soma to dendrites and was increased in white matter. 5-HT(2A)R mRNA was decreased in the male patients. 5-HT(2A)R measured by dot blots and [(3)H]ketanserin binding (B(max) and K(d)) were not significantly altered in schizophrenia. These data show that 5-HT(2A)R gene products (mRNA, protein, binding sites) are expressed in the human cerebellum at nonnegligible levels; this bears upon 5-HT(2A)R imaging studies which use the cerebellum as a reference region. 5-HT(2A)R expression is altered in schizophrenia; the shift of 5-HT(2A)R from soma to dendrites is noteworthy since atypical antipsychotics have the opposite effect. Finally, the results emphasise that expression of a receptor gene is a mutifaceted process. Measurement of multiple parameters is necessary to give a clear picture of the normal situation and to show the profile of alterations in a disease. PMID:11574947

  7. Reduced 5-HT2A receptor signaling following selective bilateral amygdala damage

    PubMed Central

    Schlaepfer, Thomas E.; Matusch, Andreas; Reich, Harald; Shah, Nadim J.; Zilles, Karl; Maier, Wolfgang; Bauer, Andreas

    2009-01-01

    Neurobiological evidence implicates the amygdala as well as serotonergic (serotonin, 5-HT) signaling via postsynaptic 5-HT2A receptors as essential substrates of anxiety behaviors. Assuming a functional interdependence of these substrates, we hypothesized that a low-fear behavioral phenotype due to bilateral lesion of the amygdala would be associated with significant 5-HT2A receptor changes. Thus, we used [18F]altanserin positron emission tomography (PET) referenced to radioligand plasma levels and corrected for partial volume effects to quantify the spatial distribution of 5-HT2A receptor binding potential (BPP) in a rare patient with Urbach–Wiethe disease and selective bilateral amygdala calcification damage relative to 10 healthy control subjects. Consistent with our a priori hypothesis, we observed a 70% global decrease in 5-HT2A receptor BPP in the Urbach–Wiethe patient relative to controls. Thus, brain abnormalities in this patient are not restricted to the amygdala, but extend to overall 5-HT neurotransmission via 5-HT2A receptors. Our findings provide important insights into the molecular architecture of human anxiety behaviors and suggest the 5-HT2A receptor as a promising pharmacological target to control pathological anxiety. PMID:19015089

  8. Serotonin 5-HT2A receptor gene variants influence antidepressant response to repeated total sleep deprivation in bipolar depression.

    PubMed

    Benedetti, Francesco; Barbini, Barbara; Bernasconi, Alessandro; Fulgosi, Mara Cigala; Colombo, Cristina; Dallaspezia, Sara; Gavinelli, Chiara; Marino, Elena; Pirovano, Adele; Radaelli, Daniele; Smeraldi, Enrico

    2008-12-12

    5-HT2A receptor density in prefrontal cortex was associated with depression and suicide. 5-HT2A receptor gene polymorphism rs6313 was associated with 5-HT2A receptor binding potential, with the ability of individuals to use environmental support in order to prevent depression, and with sleep improvement after antidepressant treatment with mirtazapine. Studies on response to antidepressant drugs gave inconsistent results. Here we studied the effect of rs6313 on response to repeated total sleep deprivation (TSD) in 80 bipolar depressed inpatients treated with three consecutive TSD cycles (each one made of 36 h awake followed by a night of undisturbed sleep). All genotype groups showed comparable acute effects of the first TSD, but patients homozygotes for the T variant had better perceived and observed benefits from treatment than carriers of the C allele. These effects became significant after the first recovery night and during the following days, leading to a 36% higher final response rate (Hamilton depression rating<8). The higher density of postsynaptic excitatory 5-HT2A receptors in T/T homozygotes could have led to higher behavioural effects of increased 5-HT neurotransmission due to repeated TSD. Other possible mechanisms involve allostatic/homeostatic adaptation to sleep loss, and a different effect of the allele variants on epigenetic influences. Results confirm the interest for individual gene variants of the serotonin pathway in shaping clinical characteristics of depression and antidepressant response.

  9. Activation of 5-HT2A/2C receptors reduces the excitability of cultured cortical neurons.

    PubMed

    Hu, Lingli; Liu, Chunhua; Dang, Minyan; Luo, Bin; Guo, Yiping; Wang, Haitao

    2016-10-01

    The abundant forebrain serotonergic projections are believed to modulate the activities of cortical neurons. 5-HT2 receptor among multiple subtypes of serotonin receptors contributes to the modulation of excitability, synaptic transmissions and plasticity. In the present study, whole-cell patch-clamp recording was adopted to examine whether activation of 5-HT2A/2C receptors would have any impact on the excitability of cultured cortical neurons. We found that 2,5-Dimethoxy-4-iodoamphetamine (DOI), a selective 5-HT2A/2C receptor agonist, rapidly and reversibly depressed spontaneous action potentials mimicking the effect of serotonin. The decreased excitability was also observed for current-evoked firing. Additionally DOI increased neuronal input resistance. Hyperpolarization-activated cyclic nucleotide-gated cationic channels (HCN) did not account for the inhibition of spontaneous firing. The synaptic contribution was ruled out in that DOI augmented excitation and attenuated inhibition to actually favor an increase in the excitability. Our findings revealed that activation of 5-HT2A/2C receptors reduces neuronal excitability, which would deepen our understanding of serotonergic modulation of cortical activities. PMID:27585751

  10. 5-HT2A receptor activation is necessary for CO2-induced arousal

    PubMed Central

    Smith, Haleigh R.; MacAskill, Amanda; Richerson, George B.

    2015-01-01

    Hypercapnia-induced arousal from sleep is an important protective mechanism pertinent to a number of diseases. Most notably among these are the sudden infant death syndrome, obstructive sleep apnea and sudden unexpected death in epilepsy. Serotonin (5-HT) plays a significant role in hypercapnia-induced arousal. The mechanism of 5-HT's role in this protective response is unknown. Here we sought to identify the specific 5-HT receptor subtype(s) involved in this response. Wild-type mice were pretreated with antagonists against 5-HT receptor subtypes, as well as antagonists against adrenergic, cholinergic, histaminergic, dopaminergic, and orexinergic receptors before challenge with inspired CO2 or hypoxia. Antagonists of 5-HT2A receptors dose-dependently blocked CO2-induced arousal. The 5-HT2C receptor antagonist, RS-102221, and the 5-HT1A receptor agonist, 8-OH-DPAT, attenuated but did not completely block CO2-induced arousal. Blockade of non-5-HT receptors did not affect CO2-induced arousal. None of these drugs had any effect on hypoxia-induced arousal. 5-HT2 receptor agonists were given to mice in which 5-HT neurons had been genetically eliminated during embryonic life (Lmx1bf/f/p) and which are known to lack CO2-induced arousal. Application of agonists to 5-HT2A, but not 5-HT2C, receptors, dose-dependently restored CO2-induced arousal in these mice. These data identify the 5-HT2A receptor as an important mediator of CO2-induced arousal and suggest that, while 5-HT neurons can be independently activated to drive CO2-induced arousal, in the absence of 5-HT neurons and endogenous 5-HT, 5-HT receptor activation can act in a permissive fashion to facilitate CO2-induced arousal via another as yet unidentified chemosensor system. PMID:25925320

  11. Serotonin 5-HT(2A) receptor activation induces 2-arachidonoylglycerol release through a phospholipase c-dependent mechanism.

    PubMed

    Parrish, Jason C; Nichols, David E

    2006-11-01

    To date, several studies have demonstrated that phospholipase C-coupled receptors stimulate the production of endocannabinoids, particularly 2-arachidonoylglycerol. There is now evidence that endocannabinoids are involved in phospholipase C-coupled serotonin 5-HT(2A) receptor-mediated behavioral effects in both rats and mice. The main objective of this study was to determine whether activation of the 5-HT(2A) receptor leads to the production and release of the endocannabinoid 2-arachidonoylglycerol. NIH3T3 cells stably expressing the rat 5-HT(2A) receptor were first incubated with [(3)H]-arachidonic acid for 24 h. Following stimulation with 10 mum serotonin, lipids were extracted from the assay medium, separated by thin layer chromatography, and analyzed by liquid scintillation counting. Our results indicate that 5-HT(2A) receptor activation stimulates the formation and release of 2-arachidonoylglycerol. The 5-HT(2A) receptor-dependent release of 2-arachidonoylglycerol was partially dependent on phosphatidylinositol-specific phospholipase C activation. Diacylglycerol produced downstream of 5-HT(2A) receptor-mediated phospholipase D or phosphatidylcholine-specific phospholipase C activation did not appear to contribute to 2-arachidonoylglycerol formation in NIH3T3-5HT(2A) cells. In conclusion, our results support a functional model where neuromodulatory neurotransmitters such as serotonin may act as regulators of endocannabinoid tone at excitatory synapses through the activation of phospholipase C-coupled G-protein coupled receptors. PMID:17010161

  12. 5-HT2A Receptor Binding in the Frontal Cortex of Parkinson's Disease Patients and Alpha-Synuclein Overexpressing Mice: A Postmortem Study.

    PubMed

    Rasmussen, Nadja Bredo; Olesen, Mikkel Vestergaard; Brudek, Tomasz; Plenge, Per; Klein, Anders Bue; Westin, Jenny E; Fog, Karina; Wörtwein, Gitta; Aznar, Susana

    2016-01-01

    The 5-HT2A receptor is highly involved in aspects of cognition and executive function and seen to be affected in neurodegenerative diseases like Alzheimer's disease and related to the disease pathology. Even though Parkinson's disease (PD) is primarily a motor disorder, reports of impaired executive function are also steadily being associated with this disease. Not much is known about the pathophysiology behind this. The aim of this study was thereby twofold: (1) to investigate 5-HT2A receptor binding levels in Parkinson's brains and (2) to investigate whether PD associated pathology, alpha-synuclein (AS) overexpression, could be associated with 5-HT2A alterations. Binding density for the 5-HT2A-specific radioligand [(3)H]-MDL 100.907 was measured in membrane suspensions of frontal cortex tissue from PD patients. Protein levels of AS were further measured using western blotting. Results showed higher AS levels accompanied by increased 5-HT2A receptor binding in PD brains. In a separate study, we looked for changes in 5-HT2A receptors in the prefrontal cortex in 52-week-old transgenic mice overexpressing human AS. We performed region-specific 5-HT2A receptor binding measurements followed by gene expression analysis. The transgenic mice showed lower 5-HT2A binding in the frontal association cortex that was not accompanied by changes in gene expression levels. This study is one of the first to look at differences in serotonin receptor levels in PD and in relation to AS overexpression. PMID:27579212

  13. 5-HT2A Receptor Binding in the Frontal Cortex of Parkinson's Disease Patients and Alpha-Synuclein Overexpressing Mice: A Postmortem Study.

    PubMed

    Rasmussen, Nadja Bredo; Olesen, Mikkel Vestergaard; Brudek, Tomasz; Plenge, Per; Klein, Anders Bue; Westin, Jenny E; Fog, Karina; Wörtwein, Gitta; Aznar, Susana

    2016-01-01

    The 5-HT2A receptor is highly involved in aspects of cognition and executive function and seen to be affected in neurodegenerative diseases like Alzheimer's disease and related to the disease pathology. Even though Parkinson's disease (PD) is primarily a motor disorder, reports of impaired executive function are also steadily being associated with this disease. Not much is known about the pathophysiology behind this. The aim of this study was thereby twofold: (1) to investigate 5-HT2A receptor binding levels in Parkinson's brains and (2) to investigate whether PD associated pathology, alpha-synuclein (AS) overexpression, could be associated with 5-HT2A alterations. Binding density for the 5-HT2A-specific radioligand [(3)H]-MDL 100.907 was measured in membrane suspensions of frontal cortex tissue from PD patients. Protein levels of AS were further measured using western blotting. Results showed higher AS levels accompanied by increased 5-HT2A receptor binding in PD brains. In a separate study, we looked for changes in 5-HT2A receptors in the prefrontal cortex in 52-week-old transgenic mice overexpressing human AS. We performed region-specific 5-HT2A receptor binding measurements followed by gene expression analysis. The transgenic mice showed lower 5-HT2A binding in the frontal association cortex that was not accompanied by changes in gene expression levels. This study is one of the first to look at differences in serotonin receptor levels in PD and in relation to AS overexpression.

  14. 5-HT2A Receptor Binding in the Frontal Cortex of Parkinson's Disease Patients and Alpha-Synuclein Overexpressing Mice: A Postmortem Study

    PubMed Central

    Rasmussen, Nadja Bredo; Olesen, Mikkel Vestergaard; Plenge, Per; Klein, Anders Bue; Westin, Jenny E.; Fog, Karina

    2016-01-01

    The 5-HT2A receptor is highly involved in aspects of cognition and executive function and seen to be affected in neurodegenerative diseases like Alzheimer's disease and related to the disease pathology. Even though Parkinson's disease (PD) is primarily a motor disorder, reports of impaired executive function are also steadily being associated with this disease. Not much is known about the pathophysiology behind this. The aim of this study was thereby twofold: (1) to investigate 5-HT2A receptor binding levels in Parkinson's brains and (2) to investigate whether PD associated pathology, alpha-synuclein (AS) overexpression, could be associated with 5-HT2A alterations. Binding density for the 5-HT2A-specific radioligand [3H]-MDL 100.907 was measured in membrane suspensions of frontal cortex tissue from PD patients. Protein levels of AS were further measured using western blotting. Results showed higher AS levels accompanied by increased 5-HT2A receptor binding in PD brains. In a separate study, we looked for changes in 5-HT2A receptors in the prefrontal cortex in 52-week-old transgenic mice overexpressing human AS. We performed region-specific 5-HT2A receptor binding measurements followed by gene expression analysis. The transgenic mice showed lower 5-HT2A binding in the frontal association cortex that was not accompanied by changes in gene expression levels. This study is one of the first to look at differences in serotonin receptor levels in PD and in relation to AS overexpression. PMID:27579212

  15. Discovering the mechanisms underlying serotonin (5-HT)2A and 5-HT2C receptor regulation following nicotine withdrawal in rats.

    PubMed

    Zaniewska, Magdalena; Alenina, Natalia; Wydra, Karolina; Fröhler, Sebastian; Kuśmider, Maciej; McCreary, Andrew C; Chen, Wei; Bader, Michael; Filip, Małgorzata

    2015-08-01

    We have previously demonstrated that nicotine withdrawal produces depression-like behavior and that serotonin (5-HT)2A/2C receptor ligands modulate that mood-like state. In the present study we aimed to identify the mechanisms (changes in radioligand binding, transcription or RNA-editing) related to such a behavioral outcome. Rats received vehicle or nicotine (0.4 mg/kg, s.c.) for 5 days in home cages. Brain 5-HT2A/2C receptors were analyzed on day 3 of nicotine withdrawal. Nicotine withdrawal increased [(3)H]ketanserin binding to 5-HT2A receptors in the ventral tegmental area and ventral dentate gyrus, yet decreased binding in the nucleus accumbens shell. Reduction in [(3)H]mesulergine binding to 5-HT2C receptors was seen in the ventral dentate gyrus. Profound decrease in the 5-HT2A receptor transcript level was noted in the hippocampus and ventral tegmental area. Out of five 5-HT2C receptor mRNA editing sites, deep sequencing data showed a reduction in editing at the E site and a trend toward reduction at the C site in the hippocampus. In the ventral tegmental area, a reduction for the frequency of CD 5-HT2C receptor transcript was seen. These results show that the reduction in the 5-HT2A receptor transcript level may be an auto-regulatory response to the increased receptor density in the hippocampus and ventral tegmental area during nicotine withdrawal, while decreased 5-HT2C receptor mRNA editing may explain the reduction in receptor labeling in the hippocampus. Serotonin (5-HT)2A/2C receptor ligands alleviate depression-like state in nicotine-withdrawn rats. Here, we show that the reduction in 5-HT2A receptor transcript level may be an auto-regulatory response to the increased receptor number in the hippocampus and ventral tegmental area during nicotine withdrawal, while attenuated 5-HT2C receptor mRNA editing in the hippocampus might explain reduced inverse agonist binding to 5-HT2C receptor and suggest a shift toward a population of more active receptors. 5

  16. The serotonin 5-HT2A and 5-HT2C receptors interact with specific sets of PDZ proteins.

    PubMed

    Bécamel, Carine; Gavarini, Sophie; Chanrion, Benjamin; Alonso, Gérard; Galéotti, Nathalie; Dumuis, Aline; Bockaert, Joël; Marin, Philippe

    2004-05-01

    The 5-hydroxytryptamine type 2A (5-HT(2A)) receptor and the 5-HT(2C) receptor are closely related members of the G-protein-coupled receptors activated by serotonin that share very similar pharmacological profiles and cellular signaling pathways. These receptors express a canonical class I PDZ ligand (SXV) at their C-terminal extremity. Here, we have identified proteins that interact with the PDZ ligand of the 5-HT(2A) and 5-HT(2C) receptors by a proteomic approach associating affinity chromatography using immobilized synthetic peptides encompassing the PDZ ligand and mass spectrometry. We report that both receptor C termini interact with specific sets of PDZ proteins in vitro. The 5-HT(2C) receptor but not the 5-HT(2A) receptor binds to the Veli-3.CASK.Mint1 ternary complex and to SAP102. In addition, the 5-HT(2C) receptor binds more strongly to PSD-95 and MPP-3 than the 5-HT(2A) receptor. In contrast, a robust interaction between the 5-HT(2A) receptor and the channel-interacting PDZ protein CIPP was found, whereas CIPP did not significantly associate with the 5-HT(2C) receptor. We also show that residues located at the -1 position and upstream the PDZ ligand in the C terminus of the 5-HT(2A) and 5-HT(2C) receptors are major determinants in their interaction with specific PDZ proteins. Immunofluorescence and electron microscopy studies strongly suggested that these specific interactions also take place in living cells and that the 5-HT(2) receptor-PDZ protein complexes occur in intracellular compartments. The interaction of the 5-HT(2A) and the 5-HT(2C) receptor with specific sets of PDZ proteins may contribute to their different signal transduction properties.

  17. The role of serotonin 5-HT2A receptors in memory and cognition

    PubMed Central

    Zhang, Gongliang; Stackman, Robert W.

    2015-01-01

    Serotonin 5-HT2A receptors (5-HT2ARs) are widely distributed in the central nervous system, especially in brain region essential for learning and cognition. In addition to endogenous 5-HT, several hallucinogens, antipsychotics, and antidepressants function by targeting 5-HT2ARs. Preclinical studies show that 5-HT2AR antagonists have antipsychotic and antidepressant properties, whereas agonist ligands possess cognition-enhancing and hallucinogenic properties. Abnormal 5-HT2AR activity is associated with a number of psychiatric disorders and conditions, including depression, schizophrenia, and drug addiction. In addition to its traditional activity as a G protein-coupled receptor (GPCR), recent studies have defined novel operations of 5-HT2ARs. Here we review progress in the (1) receptor anatomy and biology: distribution, signaling, polymerization and allosteric modulation; and (2) receptor functions: learning and memory, hallucination and spatial cognition, and mental disorders. Based on the recent progress in basic research on the 5-HT2AR, it appears that post-training 5-HT2AR activation enhances non-spatial memory consolidation, while pre-training 5-HT2AR activation facilitates fear extinction. Further, the potential influence that 5-HT2AR-elicited visual hallucinations may have on visual cue (i.e., landmark) guided spatial cognition is discussed. We conclude that the development of selective 5-HT2AR modulators to target distinct signaling pathways and neural circuits represents a new possibility for treating emotional, neuropsychiatric, and neurodegenerative disorders. PMID:26500553

  18. Expression of α(1)-adrenergic receptors in rat prefrontal cortex: cellular co-localization with 5-HT(2A) receptors.

    PubMed

    Santana, Noemí; Mengod, Guadalupe; Artigas, Francesc

    2013-06-01

    The prefrontal cortex (PFC) is involved in behavioural control and cognitive processes that are altered in schizophrenia. The brainstem monoaminergic systems control PFC function, yet the cells/networks involved are not fully known. Serotonin (5-HT) and norepinephrine (NE) increase PFC neuronal activity through the activation of α(1)-adrenergic receptors (α(1)ARs) and 5-HT(2A) receptors (5-HT(2A)Rs), respectively. Neurochemical and behavioural interactions between these receptors have been reported. Further, classical and atypical antipsychotic drugs share nm in vitro affinity for α(1)ARs while having preferential affinity for D(2) and 5-HT(2A)Rs, respectively. Using double in situ hybridization we examined the cellular expression of α(1)ARs in pyramidal (vGluT1-positive) and GABAergic (GAD(65/67)-positive) neurons in rat PFC and their co-localization with 5-HT(2A)Rs. α(1)ARs are expressed by a high proportion of pyramidal (59-85%) and GABAergic (52-79%) neurons. The expression in pyramidal neurons exhibited a dorsoventral gradient, with a lower percentage of α(1)AR-positive neurons in infralimbic cortex compared to anterior cingulate and prelimbic cortex. The expression of α(1A), α(1B) and α(1D) adrenergic receptors was segregated in different layers and subdivisions. In all them there is a high co-expression with 5-HT(2A)Rs (∼80%). These observations indicate that NE controls the activity of most PFC pyramidal neurons via α(1)ARs, either directly or indirectly, via GABAergic interneurons. Antipsychotic drugs can thus modulate the activity of PFC via α(1)AR blockade. The high co-expression with 5-HT(2A)Rs indicates a convergence of excitatory serotonergic and noradrenergic inputs onto the same neuronal populations. Moreover, atypical antipsychotics may exert a more powerful control of PFC function through the simultaneous blockade of α(1)ARs and 5-HT(2A)Rs.

  19. 5-HT2A receptors control body temperature in mice during LPS-induced inflammation via regulation of NO production.

    PubMed

    Voronova, Irina P; Khramova, Galina M; Kulikova, Elizabeth A; Petrovskii, Dmitrii V; Bazovkina, Daria V; Kulikov, Alexander V

    2016-01-01

    G protein-coupled 5-HT2A receptors are involved in the regulation of numerous normal and pathological physiological functions. At the same time, its involvement in the regulation of body temperature (Tb) in normal conditions is obscure. Here we study the effect of the 5-HT2A receptor activation or blockade on Tb in sick animals. The experiments were carried out on adult C57BL/6 mouse males. Systemic inflammation and sickness were produced by lipopolysaccharide (LPS, 0.1mg/kg, ip), while the 5-HT2A receptor was stimulated or blocked through the administration of the receptor agonist DOI or antagonist ketanserin (1mg/kg), respectively. LPS, DOI or ketanserin alone produced no effect on Tb. However, administration of LPS together with a peripheral or central ketanserin injection reduced Tb (32.2°C). Ketanserin reversed the LPS-induced expression of inducible NO synthase in the brain. Consequently, an involvement of NO in the mechanism of the hypothermic effect of ketanserin in sick mice was hypothesized. Administration of LPS together with NO synthase inhibitor, l-nitro-arginine methyl ester (60mg/kg, ip) resulted in deep (28.5°C) and prolonged (8h) hypothermia, while administration of l-nitro-arginine methyl ester alone produced no effect on Tb. Thus, 5-HT2A receptors play a key role in Tb control in sick mice. Blockade of this GPCR produces hypothermia in mice with systemic inflammation via attenuation of LPS-induced NO production. These results indicate an unexpected role of 5-HT2A receptors in inflammation and NO production and have a considerable biological impact on understanding the mechanism of animal adaptation to pathogens and parasites. Moreover, adverse side effects of 5-HT2A receptor antagonists in patients with inflammation may be expected. PMID:26621247

  20. 5-HT2A receptors control body temperature in mice during LPS-induced inflammation via regulation of NO production.

    PubMed

    Voronova, Irina P; Khramova, Galina M; Kulikova, Elizabeth A; Petrovskii, Dmitrii V; Bazovkina, Daria V; Kulikov, Alexander V

    2016-01-01

    G protein-coupled 5-HT2A receptors are involved in the regulation of numerous normal and pathological physiological functions. At the same time, its involvement in the regulation of body temperature (Tb) in normal conditions is obscure. Here we study the effect of the 5-HT2A receptor activation or blockade on Tb in sick animals. The experiments were carried out on adult C57BL/6 mouse males. Systemic inflammation and sickness were produced by lipopolysaccharide (LPS, 0.1mg/kg, ip), while the 5-HT2A receptor was stimulated or blocked through the administration of the receptor agonist DOI or antagonist ketanserin (1mg/kg), respectively. LPS, DOI or ketanserin alone produced no effect on Tb. However, administration of LPS together with a peripheral or central ketanserin injection reduced Tb (32.2°C). Ketanserin reversed the LPS-induced expression of inducible NO synthase in the brain. Consequently, an involvement of NO in the mechanism of the hypothermic effect of ketanserin in sick mice was hypothesized. Administration of LPS together with NO synthase inhibitor, l-nitro-arginine methyl ester (60mg/kg, ip) resulted in deep (28.5°C) and prolonged (8h) hypothermia, while administration of l-nitro-arginine methyl ester alone produced no effect on Tb. Thus, 5-HT2A receptors play a key role in Tb control in sick mice. Blockade of this GPCR produces hypothermia in mice with systemic inflammation via attenuation of LPS-induced NO production. These results indicate an unexpected role of 5-HT2A receptors in inflammation and NO production and have a considerable biological impact on understanding the mechanism of animal adaptation to pathogens and parasites. Moreover, adverse side effects of 5-HT2A receptor antagonists in patients with inflammation may be expected.

  1. Reelin influences the expression and function of dopamine D2 and serotonin 5-HT2A receptors: a comparative study.

    PubMed

    Varela, M J; Lage, S; Caruncho, H J; Cadavid, M I; Loza, M I; Brea, J

    2015-04-01

    Reelin is an extracellular matrix protein that plays a critical role in neuronal guidance during brain neurodevelopment and in synaptic plasticity in adults and has been associated with schizophrenia. Reelin mRNA and protein levels are reduced in various structures of post-mortem schizophrenic brains, in a similar way to those found in heterozygous reeler mice (HRM). Reelin is involved in protein expression in dendritic spines that are the major location where synaptic connections are established. Thus, we hypothesized that a genetic deficit in reelin would affect the expression and function of dopamine D2 and serotonin 5-HT2A receptors that are associated with the action of current antipsychotic drugs. In this study, D2 and 5-HT2A receptor expression and function were quantitated by using radioligand binding studies in the frontal cortex and striatum of HRM and wild-type mice (WTM). We observed increased expression (p<0.05) in striatum membranes and decreased expression (p<0.05) in frontal cortex membranes for both dopamine D2 and serotonin 5-HT2A receptors from HRM compared to WTM. Our results show parallel alterations of D2 and 5-HT2A receptors that are compatible with a possible hetero-oligomeric nature of these receptors. These changes are similar to changes described in schizophrenic patients and provide further support for the suitability of using HRM as a model for studying this disease and the effects of antipsychotic drugs. PMID:25637489

  2. The antidepressant 5-HT2A receptor antagonists pizotifen and cyproheptadine inhibit serotonin-enhanced platelet function.

    PubMed

    Lin, Olivia A; Karim, Zubair A; Vemana, Hari Priya; Espinosa, Enma V P; Khasawneh, Fadi T

    2014-01-01

    There is considerable interest in defining new agents or targets for antithrombotic purposes. The 5-HT2A receptor is a G-protein coupled receptor (GPCR) expressed on many cell types, and a known therapeutic target for many disease states. This serotonin receptor is also known to regulate platelet function. Thus, in our FDA-approved drug repurposing efforts, we investigated the antiplatelet activity of cyproheptadine and pizotifen, two antidepressant 5-HT2A Receptor antagonists. Our results revealed that cyproheptadine and pizotifen reversed serotonin-enhanced ADP-induced platelet aggregation in vitro and ex vivo. And the inhibitory effects of these two agents were found to be similar to that of EMD 281014, a 5-HT2A Receptor antagonist under development. In separate experiments, our studies revealed that these 5-HT2A receptor antagonists have the capacity to reduce serotonin-enhanced ADP-induced elevation in intracellular calcium levels and tyrosine phosphorylation. Using flow cytometry, we also observed that cyproheptadine, pizotifen, and EMD 281014 inhibited serotonin-enhanced ADP-induced phosphatidylserine (PS) exposure, P-selectin expression, and glycoprotein IIb-IIIa activation. Furthermore, using a carotid artery thrombosis model, these agents prolonged the time for thrombotic occlusion in mice in vivo. Finally, the tail-bleeding time was investigated to assess the effect of cyproheptadine and pizotifen on hemostasis. Our findings indicated prolonged bleeding time in both cyproheptadine- and pizotifen-treated mice. Notably, the increases in occlusion and bleeding times associated with these two agents were comparable to that of EMD 281014, and to clopidogrel, a commonly used antiplatelet drug, again, in a fashion comparable to clopidogrel and EMD 281014. Collectively, our data indicate that the antidepressant 5-HT2A antagonists, cyproheptadine and pizotifen do exert antiplatelet and thromboprotective effects, but similar to clopidogrel and EMD 281014, their

  3. Anti-thrombotic and vascular effects of AR246686, a novel 5-HT2A receptor antagonist.

    PubMed

    Adams, John W; Ramirez, Juan; Ortuno, Danny; Shi, Yunqing; Thomsen, William; Richman, Jeremy G; Morgan, Michael; Dosa, Peter; Teegarden, Bradley R; Al-Shamma, Hussien; Behan, Dominic P; Connolly, Daniel T

    2008-05-31

    We have evaluated the anti-platelet and vascular pharmacology of AR246686, a novel 5-hydroxytryptamine2A (5-HT2A) receptor antagonist. AR246686 displayed high affinity binding to membranes of HEK cells stably expressing recombinant human and rat 5-HT2A receptors (Ki=0.2 nM and 0.4 nM, respectively). Functional antagonism (IC50=1.9 nM) with AR246686 was determined by inhibition of ligand-independent inositol phosphate accumulation in the 5-HT2A stable cell line. We observed 8.7-fold and 1360-fold higher affinity of AR246686 for the 5-HT2A receptor vs. 5-HT2C and 5-HT2B receptors, respectively. AR246686 inhibited 5-HT-induced amplification of ADP-stimulated human platelet aggregation (IC50=21 nM). Similar potency was observed for inhibition of 5-HT stimulated DNA synthesis in rat aortic smooth muscle cells (IC(50)=10 nM) and 5-HT-mediated contraction in rat aortic rings. Effects of AR246686 on arterial thrombosis and bleeding time were studied in a rat model of femoral artery occlusion. Oral dosing of AR246686 to rats resulted in prolongation of time to occlusion at 1 mg/kg, whereas increased bleeding time was observed at a dose of 20 mg/kg. In contrast, both bleeding time and time to occlusion were increased at the same dose (10 mg/kg) of clopidogrel. These results demonstrate that AR246686 is a high affinity 5-HT2A receptor antagonist with potent activity on platelets and vascular smooth muscle. Further, oral administration results in anti-thrombotic effects at doses that are free of significant effects on traumatic bleeding time.

  4. APORPHINOID ANTAGONISTS OF 5-HT2A RECEPTORS: FURTHER EVALUATION OF RING A SUBSTITUENTS AND THE SIZE OF RING C

    PubMed Central

    Ponnala, Shashikanth; Kapadia, Nirav; Navarro, Hernán A.; Harding, Wayne W.

    2014-01-01

    A series of ring A modified analogs of nantenine as well as structural variants in ring C were synthesized and evaluated for antagonist activity at 5-HT2A and α1A receptors. Halogenation improves 5-HT2A antagonist potency in molecules containing a C1 methoxyl/C2 methoxyl or C1 methoxyl/C2 hydroxyl moiety. Bromination or iodination (but not chlorination) with the latter moiety also significantly increased α1A antagonist potency. Homologation or contraction of ring C adversely affected antagonist activity at both receptors, implying that a six-membered ring C motif is beneficial for high antagonist potency at both receptors. Molecular docking studies suggest that the improved antagonist activity (by virtue of improved affinity) of C3 halogenated aporphines in this study, is attributable to favorable interactions with the C3 halogen and F339 and/or F340. PMID:24766771

  5. Chronic treatment with LY341495 decreases 5-HT(2A) receptor binding and hallucinogenic effects of LSD in mice.

    PubMed

    Moreno, José L; Holloway, Terrell; Rayannavar, Vinayak; Sealfon, Stuart C; González-Maeso, Javier

    2013-03-01

    Hallucinogenic drugs, such as lysergic acid diethylamide (LSD), mescaline and psilocybin, alter perception and cognitive processes. All hallucinogenic drugs have in common a high affinity for the serotonin 5-HT(2A) receptor. Metabotropic glutamate 2/3 (mGlu2/3) receptor ligands show efficacy in modulating the cellular and behavioral responses induced by hallucinogenic drugs. Here, we explored the effect of chronic treatment with the mGlu2/3 receptor antagonist 2S-2-amino-2-(1S,2S-2-carboxycyclopropan-1-yl)-3-(xanth-9-yl)-propionic acid (LY341495) on the hallucinogenic-like effects induced by LSD (0.24mg/kg). Mice were chronically (21 days) treated with LY341495 (1.5mg/kg), or vehicle, and experiments were carried out one day after the last injection. Chronic treatment with LY341495 down-regulated [(3)H]ketanserin binding in somatosensory cortex of wild-type, but not mGlu2 knockout (KO), mice. Head-twitch behavior, and expression of c-fos, egr-1 and egr-2, which are responses induced by hallucinogenic 5-HT(2A) agonists, were found to be significantly decreased by chronic treatment with LY341495. These findings suggest that repeated blockade of the mGlu2 receptor by LY341495 results in reduced 5-HT(2A) receptor-dependent hallucinogenic effects of LSD.

  6. N-acetylcysteine modulates hallucinogenic 5-HT(2A) receptor agonist-mediated responses: behavioral, molecular, and electrophysiological studies.

    PubMed

    Lee, Mei-Yi; Chiang, Chun-Cheng; Chiu, Hong-Yi; Chan, Ming-Huan; Chen, Hwei-Hsien

    2014-06-01

    N-acetylcysteine (NAC) has been reported to reverse the psychotomimetic effects in the rodent phencyclidine model of psychosis and shown beneficial effects in treating patients with schizophrenia. The effect of NAC has been associated with facilitating the activity of cystine-glutamate antiporters on glial cells concomitant with the release of non-vesicular glutamate, which mainly stimulates the presynaptic metabotropic glutamate receptor subtype 2 receptors (mGluR2). Recent evidence demonstrated that functional interactions between serotonin 5-HT2A receptor (5-HT(2A)R) and mGluR2 are responsible to unique cellular responses when targeted by hallucinogenic drugs. The present study determined the effects of NAC on hallucinogenic 5-HT(2A)R agonist (±)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-elicited behavioral and molecular responses in mice and DOI-evoked field potentials in the mouse cortical slices. NAC significantly attenuated DOI-induced head twitch response and expression of c-Fos and Egr-2 in the infralimbic and motor cortex and suppressed the increase in the frequency of excitatory field potentials elicited by DOI in the medial prefrontal cortex. In addition, the cystine-glutamate antiporter inhibitor (S)-4-carboxyphenylglycine (CPG) and the mGluR2 antagonist LY341495 reversed the suppressing effects of NAC on DOI-induced head twitch and molecular responses and increased frequency of excitatory field potentials, supporting that NAC attenuates the 5-HT(2A)R-mediated hallucinogenic effects via increased activity of cystine-glutamate antiporter followed by activation of mGluR2 receptors. These findings implicate NAC as a potential therapeutic agent for hallucinations and psychosis associated with hallucinogen use and schizophrenia.

  7. Blockade of 5-HT2A receptors suppresses hyperthermic but not cardiovascular responses to psychosocial stress in rats.

    PubMed

    Beig, M I; Baumert, M; Walker, F R; Day, T A; Nalivaiko, E

    2009-03-31

    The aim of this study was to determine whether 5-HT2A receptors mediate cardiovascular and thermogenic responses to acute psychological stresses. For this purpose, adult male Wistar hooded rats instrumented for telemetric recordings of either electrocardiogram (ECG) (n=12) or arterial pressure (n=12) were subjected, on different days, to four 15-min episodes of social defeat. Prior to stress, animals received s.c. injection of the selective 5-HT2A receptor antagonist SR-46349B (trans-4-((3Z)3-[(2-dimethylaminoethyl)oxyimino]-3-(2-fluorophenyl)propen-1-yl)-phenol, hemifumarate) (at doses of 0.3, 1.0 and 3.0 mg/kg) or vehicle. The drug had no effect on basal heart rate or heart rate variability indexes, arterial pressure, and core body temperature. Social defeat elicited significant and substantial tachycardic (347+/-7 to 500+/-7 bpm), pressor (77+/-4 to 97+/-4 mm Hg) and hyperthermic (37.0+/-0.3 to 38.5+/-0.1 degrees C) responses. Blockade of 5-HT2A receptors, at all doses of the antagonist, completely prevented stress-induced hyperthermia. In contrast, stress-induced cardiovascular responses were not affected by the blockade (except small reduction of tachycardia by the highest dose of the drug). We conclude that in rats, 5-HT2A receptors mediate stress-induced hyperthermic responses, but are not involved in the genesis of stress-induced rises in heart rate or arterial pressure, and do not participate in cardiovascular control at rest. PMID:19356699

  8. Clozapine, but not olanzapine, disrupts conditioned avoidance response in rats by antagonizing 5-HT2A/2C receptors.

    PubMed

    Li, Ming; Sun, Tao; Mead, Alexa

    2012-04-01

    The present study was designed to assess the role of 5-HT(2A/2C) receptors in the acute and repeated effect of clozapine and olanzapine in a rat conditioned avoidance response model, a validated model of antipsychotic activity. Male Sprague-Dawley rats that were previously treated with either phencyclidine (0.5-2.0 mg/kg, sc), amphetamine (1.25-5.0 mg/kg, sc), or saline and tested in a prepulse inhibition of acoustic startle study were used. They were first trained to acquire avoidance response to a white noise (CS1) and a pure tone (CS2) that differed in their ability to predict the occurrence of footshock. Those who acquired avoidance response were administered with clozapine (10.0 mg/kg, sc) or olanzapine (1.0 mg/kg, sc) together with either saline or 1-2,5-dimethoxy-4-iodo-amphetamine (DOI, a selective 5-HT(2A/2C) agonist, 1.0 or 2.5 mg/kg, sc), and their conditioned avoidance responses were tested for four consecutive days. After two drug-free retraining days, the long-term repeated effect was assessed in a challenge test during which all rats were injected with a low dose of clozapine (5 mg/kg, sc) or olanzapine (0.5 mg/kg). Results show that pretreatment of DOI dose-dependently reversed the acute disruptive effect of clozapine on both CS1 and CS2 avoidance responses, whereas it had little effect in reversing the acute effect of olanzapine. On the challenge test, pretreatment of DOI did not alter the clozapine-induced tolerance or the olanzapine-induced sensitization effect. These results confirmed our previous findings and suggest that clozapine, but not olanzapine, acts on through 5-HT(2A/2C) receptors to achieve its acute avoidance disruptive effect and likely its therapeutic effects. The long-term clozapine tolerance and olanzapine sensitization effects appear to be mediated by non-5-HT(2A/2C) receptors.

  9. C-(4,5,6-trimethoxyindan-1-yl)methanamine: a mescaline analogue designed using a homology model of the 5-HT2A receptor.

    PubMed

    McLean, Thomas H; Chambers, James J; Parrish, Jason C; Braden, Michael R; Marona-Lewicka, Danuta; Kurrasch-Orbaugh, Deborah; Nichols, David E

    2006-07-13

    A conformationally restricted analogue of mescaline, C-(4,5,6-trimethoxyindan-1-yl)-methanamine, was designed using a 5-HT(2A) receptor homology model. The compound possessed 3-fold higher affinity and potency than and efficacy equal to that of mescaline at the 5-HT(2A) receptor. The new analogue substituted fully for LSD in drug discrimination studies and was 5-fold more potent than mescaline. Resolution of this analogue into its enantiomers corroborated the docking experiments, showing the R-(+) isomer to have higher affinity and potency and to have efficacy similar to that of mescaline at the 5-HT(2A) receptor.

  10. Latent inhibition is attenuated by noise and partially restored by a 5-HT2A receptor antagonist.

    PubMed

    McDonald, L M; Moran, P M; Vythelingum, G N; Joseph, M H; Stephenson, J D; Gray, J A

    2002-12-01

    Latent inhibition (LI) is a model of attention, which is a cognitive process that can be modulated by stressors such as chronic intermittent broadband noise, e.g. caused by building work, which is particularly stressful to rats. The aim of this study was to analyse the effect of chronic noise stress, caused by a building project, on LI, and its interaction with SR 46,349B, a 5-HT2A receptor antagonist. Control groups from LI experiments conducted during periods of chronic intermittent noise were compared with control groups from LI experiments conducted in normal quiet conditions. The interaction of SR 46,349B with the effects of chronic noise stress was then tested. Chronic intermittent noise attenuated LI, an effect which was partially reversed by SR 46,349B, 2.4 mg/kg i.p. Attenuation of LI by chronic intermittent noise and reversal of this effect by SR 46,349B support suggestions that stress can modulate attention and that 5-HT2A receptors are involved in mediating the effects of chronic stress.

  11. Effects of dominance status on conditioned defeat and expression of 5-HT1A and 5-HT2A receptors

    PubMed Central

    Morrison, Kathleen E.; Swallows, Cody L.; Cooper, Matthew A.

    2011-01-01

    Past experience can alter how individuals respond to stressful events. The brain serotonin system is a key factor modulating stress-related behavior and may contribute to individual variation in coping styles. In this study we investigated whether dominant and subordinate hamsters respond differently to social defeat and whether their behavioral responses are associated with changes in 5-HT1A and 5-HT2A receptor immunoreactivity in several limbic brain regions. We paired weight-matched hamsters in daily aggressive encounters for two weeks so that they formed a stable dominance relationship. We also included controls that were exposed to an empty cage each day for two weeks. Twenty-four hours after the final pairing or empty cage exposure, subjects were socially defeated in 3, 5-min encounters with a more aggressive hamster. Twenty-four hours after social defeat, animals were tested for conditioned defeat in a 5-min social interaction test with a non-aggressive intruder. We collected brains following conditioned defeat testing and performed immunohistochemistry for 5-HT1A and 5-HT2A receptors. We found that dominants showed less submissive and defensive behavior at conditioned defeat testing compared to both subordinates and controls. Additionally, both dominants and subordinates had an increased number of 5-HT1A immunopositive cells in the basolateral amygdala compared to controls. Subordinates also had more 5-HT1A immunopositive cells in the dorsal medial amygdala than did controls. Finally, dominants had fewer 5-HT1A immunopositive cells in the paraventricular nucleus of the hypothalamus compared to controls. Our results indicate that dominant social status results in a blunted conditioned defeat response and a distinct pattern of 5-HT1A receptor expression, which may contribute to resistance to conditioned defeat. PMID:21362435

  12. Effects of dominance status on conditioned defeat and expression of 5-HT1A and 5-HT2A receptors.

    PubMed

    Morrison, Kathleen E; Swallows, Cody L; Cooper, Matthew A

    2011-08-01

    Past experience can alter how individuals respond to stressful events. The brain serotonin system is a key factor modulating stress-related behavior and may contribute to individual variation in coping styles. In this study we investigated whether dominant and subordinate hamsters respond differently to social defeat and whether their behavioral responses are associated with changes in 5-HT1A and 5-HT2A receptor immunoreactivity in several limbic brain regions. We paired weight-matched hamsters in daily aggressive encounters for two weeks so that they formed a stable dominance relationship. We also included controls that were exposed to an empty cage each day for two weeks. Twenty-four hours after the final pairing or empty cage exposure, subjects were socially defeated in 3, 5-min encounters with a more aggressive hamster. Twenty-four hours after social defeat, animals were tested for conditioned defeat in a 5-min social interaction test with a non-aggressive intruder. We collected brains following conditioned defeat testing and performed immunohistochemistry for 5-HT1A and 5-HT2A receptors. We found that dominants showed less submissive and defensive behavior at conditioned defeat testing compared to both subordinates and controls. Additionally, both dominants and subordinates had an increased number of 5-HT1A immunopositive cells in the basolateral amygdala compared to controls. Subordinates also had more 5-HT1A immunopositive cells in the dorsal medial amygdala than did controls. Finally, dominants had fewer 5-HT1A immunopositive cells in the paraventricular nucleus of the hypothalamus compared to controls. Our results indicate that dominant social status results in a blunted conditioned defeat response and a distinct pattern of 5-HT1A receptor expression, which may contribute to resistance to conditioned defeat.

  13. The 5-HT2A serotonin receptor in executive function: Implications for neuropsychiatric and neurodegenerative diseases.

    PubMed

    Aznar, Susana; Hervig, Mona El-Sayed

    2016-05-01

    Executive function entails the interplay of a group of cognitive processes enabling the individual to anticipate consequences, attain self-control, and undertake appropriate goal-directed behaviour. Serotonin signalling at serotonin 2A receptors (5-HT2AR) has important effects on these behavioural and cognitive pathways, with the prefrontal cortex (PFC) as the central actor. Indeed, the 5-HT2ARs are highly expressed in PFC, where they modulate cortical activity and local network oscillations (brain waves). Numerous psychiatric and neurodegenerative diseases result in disrupted executive function. Animal and human studies have linked these disorders with alterations in the 5-HT2AR system, making this an important pharmacological target for the treatment of disorders with impaired cognitive function. This review aims to describe the current state of knowledge on the role of 5-HT2AR signalling in components of executive function, and how 5-HT2AR systems may relate to executive dysfunctions occurring in psychiatric and neurodegenerative diseases. We hope thereby to provide insight into how pharmacotherapy targeting the 5-HT2AR may ameliorate (or exacerbate) aspects of these disorders. PMID:26891819

  14. 4-Bromo-2,5-dimethoxyphenethylamine (2C-B) and structurally related phenylethylamines are potent 5-HT2A receptor antagonists in Xenopus laevis oocytes

    PubMed Central

    Villalobos, Claudio A; Bull, Paulina; Sáez, Patricio; Cassels, Bruce K; Huidobro-Toro, J Pablo

    2004-01-01

    We recently described that several 2-(2,5-dimethoxy-4-substituted phenyl)ethylamines (PEAs), including 4-I=2C-I, 4-Br=2C-B, and 4-CH3=2C-D analogs, are partial agonists at 5-HT2C receptors, and show low or even negligible intrinsic efficacy at 5-HT2A receptors. These results raised the proposal that these drugs may act as 5-HT2 antagonists. To test this hypothesis, Xenopus laevis oocytes were microinjected with the rat clones for 5-HT2A or 5-HT2C receptors. The above-mentioned PEAs and its 4-H analog (2C-H) blocked the 5-HT-induced currents at 5-HT2A, but not at the 5-HT2C receptor, revealing 5-HT2 receptor subtype selectivity. The 5-HT2A receptor antagonism required a 2-min preincubation to attain maximum inhibition. All PEAs tested shifted the 5-HT concentration–response curves to the right and downward. Their potencies varied with the nature of the C(4) substituent; the relative rank order of their 5-HT2A receptor antagonist potency was 2C-I>2C-B>2C-D>2C-H. The present results demonstrate that in X. laevis oocytes, a series of 2,5-dimethoxy-4-substituted PEAs blocked the 5-HT2A but not the 5-HT2C receptor-mediated responses. As an alternative hypothesis, we suggest that the psychostimulant activity of the PEAs may not be exclusively associated with partial or full 5-HT2A receptor agonism. PMID:15006903

  15. Pyramidal Neurons in Rat Prefrontal Cortex Projecting to Ventral Tegmental Area and Dorsal Raphe Nucleus Express 5-HT2A Receptors

    PubMed Central

    Vázquez-Borsetti, Pablo; Cortés, Roser

    2009-01-01

    The prefrontal cortex (PFC) is involved in higher brain functions altered in schizophrenia. Classical antipsychotics modulate cortico-limbic circuits mainly through subcortical D2 receptor blockade, whereas second generation (atypical) antipsychotics preferentially target cortical 5-HT receptors. Anatomical and functional evidence supports a PFC-based control of the brainstem monoaminergic nuclei. Using a combination of retrograde tracing experiments and in situ hybridization we report that a substantial proportion of PFC pyramidal neurons projecting to the dorsal raphe (DR) and/or ventral tegmental area (VTA) express 5-HT2A receptors. Cholera-toxin B application into the DR and the VTA retrogradely labeled projection neurons in the medial PFC (mPFC) and in orbitofrontal cortex (OFC). In situ hybridization of 5-HT2A receptor mRNA in the same tissue sections labeled a large neuronal population in mPFC and OFC. The percentage of DR-projecting neurons expressing 5-HT2A receptor mRNA was ∼60% in mPFC and ∼75% in OFC (n = 3). Equivalent values for VTA-projecting neurons were ∼55% in both mPFC and ventral OFC. Thus, 5-HT2A receptor activation/blockade in PFC may have downstream effects on dopaminergic and serotonergic systems via direct descending pathways. Atypical antipsychotics may distally modulate monoaminergic cells through PFC 5-HT2A receptor blockade, presumably decreasing the activity of neurons receiving direct cortical inputs. PMID:19029064

  16. Small molecule drug screening in Drosophila identifies the 5HT2A receptor as a feeding modulation target

    PubMed Central

    Gasque, Gabriel; Conway, Stephen; Huang, Juan; Rao, Yi; Vosshall, Leslie B.

    2013-01-01

    Dysregulation of eating behavior can lead to obesity, which affects 10% of the adult population worldwide and accounts for nearly 3 million deaths every year. Despite this burden on society, we currently lack effective pharmacological treatment options to regulate appetite. We used Drosophila melanogaster larvae to develop a high-throughput whole organism screen for drugs that modulate food intake. In a screen of 3630 small molecules, we identified the serotonin (5-hydroxytryptamine or 5-HT) receptor antagonist metitepine as a potent anorectic drug. Using cell-based assays we show that metitepine is an antagonist of all five Drosophila 5-HT receptors. We screened fly mutants for each of these receptors and found that serotonin receptor 5-HT2A is the sole molecular target for feeding inhibition by metitepine. These results highlight the conservation of molecular mechanisms controlling appetite and provide a method for unbiased whole-organism drug screens to identify novel drugs and molecular pathways modulating food intake. PMID:23817146

  17. Potential role of cortical 5-HT(2A) receptors in the anxiolytic action of cyamemazine in benzodiazepine withdrawal.

    PubMed

    Benyamina, Amine; Naassila, Mickaël; Bourin, Michel

    2012-07-30

    The antipsychotic cyamemazine is a potent serotonin 5-HT(2A) receptor (5-HT(2AR)) antagonist. A positron emission tomography (PET) study in human patients showed that therapeutic doses of cyamemazine produced near saturation of 5-HT(2AR) occupancy in the frontal cortex, whereas dopamine D(2) occupancy remained below the level for motor side effects observed with typical antipsychotics. Recently, numerous studies have revealed the involvement of 5-HT(2AR) in the pathophysiology of anxiety and a double-blind, randomized clinical trial showed similar efficacy of cyamemazine and bromazepam in reducing the anxiety associated with benzodiazepine withdrawal. Therefore, we reviewed the above articles about 5-HT(2AR) and anxiety in order to understand better the anxiolytic mechanisms of cyamemazine in benzodiazepine withdrawal. The 5-HT(2AR) is the most abundant serotonin receptor subtype in the cortex. Non-pharmacological studies with antisense oligodeoxynucleotides and genetically modified mice clearly showed that cortical 5-HT(2AR) signaling positively modulates anxiety-like behavior. With a few exceptions, most other studies reviewed here further support this view. Therefore, the anxiolytic efficacy of cyamemazine in benzodiazepine withdrawal can be due to a 5-HT(2AR) antagonistic activity at the cortical level.

  18. Cartography of 5-HT1A and 5-HT2A Receptor Subtypes in Prefrontal Cortex and Its Projections.

    PubMed

    Mengod, Guadalupe; Palacios, José M; Cortés, Roser

    2015-07-15

    Since the development of chemical neuroanatomical tools in the 1960s, a tremendous wealth of information has been generated on the anatomical components of the serotonergic system, at the microscopic level in the brain including the prefrontal cortex (PFC). The PFC receives a widespread distribution of serotonin (5-hydroxytryptamine, 5-HT) terminals from the median and dorsal raphe nuclei. 5-HT receptors were first visualized using radioligand autoradiography in the late 1980s and early 1990s and showed, in contrast to 5-HT innervation, a differential distribution of binding sites associated with different 5-HT receptor subtypes. Due to the cloning of the different 5-HT receptor subtype genes in the late 1980s and early 1990s, it was possible, using in situ hybridization histochemistry, to localize cells expressing mRNA for these receptors. Double in situ hybridization histochemistry and immunohistochemistry allowed for the chemical characterization of the phenotype of cells expressing 5-HT receptors. Tract tracing technology allowed a detailed cartography of the neuronal connections of PFC and other brain areas. Based on these data, maps have been constructed that reflect our current understanding of the different circuits where 5-HT receptors can modulate the electrophysiological, pharmacological, and behavioral functions of the PFC. We will review current knowledge regarding the cellular localization of 5-HT1A and 5-HT2A receptors in mammalian PFC and their possible functions in the neuronal circuits of the PFC. We will discuss data generated in our laboratory as well as in others, focusing on localization in the pyramidal and GABAergic neuronal cell populations in different mammalian species using molecular neuroanatomy and on the connections with other brain regions. PMID:25739427

  19. Cartography of 5-HT1A and 5-HT2A Receptor Subtypes in Prefrontal Cortex and Its Projections.

    PubMed

    Mengod, Guadalupe; Palacios, José M; Cortés, Roser

    2015-07-15

    Since the development of chemical neuroanatomical tools in the 1960s, a tremendous wealth of information has been generated on the anatomical components of the serotonergic system, at the microscopic level in the brain including the prefrontal cortex (PFC). The PFC receives a widespread distribution of serotonin (5-hydroxytryptamine, 5-HT) terminals from the median and dorsal raphe nuclei. 5-HT receptors were first visualized using radioligand autoradiography in the late 1980s and early 1990s and showed, in contrast to 5-HT innervation, a differential distribution of binding sites associated with different 5-HT receptor subtypes. Due to the cloning of the different 5-HT receptor subtype genes in the late 1980s and early 1990s, it was possible, using in situ hybridization histochemistry, to localize cells expressing mRNA for these receptors. Double in situ hybridization histochemistry and immunohistochemistry allowed for the chemical characterization of the phenotype of cells expressing 5-HT receptors. Tract tracing technology allowed a detailed cartography of the neuronal connections of PFC and other brain areas. Based on these data, maps have been constructed that reflect our current understanding of the different circuits where 5-HT receptors can modulate the electrophysiological, pharmacological, and behavioral functions of the PFC. We will review current knowledge regarding the cellular localization of 5-HT1A and 5-HT2A receptors in mammalian PFC and their possible functions in the neuronal circuits of the PFC. We will discuss data generated in our laboratory as well as in others, focusing on localization in the pyramidal and GABAergic neuronal cell populations in different mammalian species using molecular neuroanatomy and on the connections with other brain regions.

  20. Maternal lipopolysaccharide treatment differentially affects 5-HT(2A) and mGlu2/3 receptor function in the adult male and female rat offspring.

    PubMed

    Wischhof, Lena; Irrsack, Ellen; Dietz, Frank; Koch, Michael

    2015-10-01

    Maternal infection during pregnancy increases the risk for the offspring to develop schizophrenia. However, it is still not fully understood which biochemical mechanisms are responsible for the emergence of neuropsychiatric symptoms following prenatal immune activation. The serotonin (5-hydroxytryptamine, 5-HT) and glutamate system have prominently been associated with the schizophrenia pathophysiology but also with the mechanism of antipsychotic drug actions. Here, we investigated the behavioral and cellular response to 5-HT2A and metabotropic glutamate (mGlu)2/3 receptor stimulation in male and female offspring born to lipopolysaccharide (LPS)-treated mothers. Additionally, we assessed protein expression levels of prefrontal 5-HT2A and mGlu2 receptors. Prenatally LPS-exposed male and female offspring showed locomotor hyperactivity and increased head-twitch behavior in response to the 5-HT2A receptor agonist DOI. In LPS-exposed male offspring, the mGlu2/3 receptor agonist LY379268 failed to reduce DOI-induced prepulse inhibition deficits. In LPS-males, the behavioral changes were further accompanied by enhanced DOI-induced c-Fos protein expression and an up-regulation of prefrontal 5-HT2A receptors. No changes in either 5-HT2A or mGlu2 receptor protein levels were found in female offspring. Our data support the hypothesis of an involvement of maternal infection during pregnancy contributing, at least partially, to the pathology of schizophrenia. Identifying biochemical alterations that parallel the behavioral deficits may help to improve therapeutic strategies in the treatment of this mental illness. Since most studies in rodents almost exclusively include male subjects, our data further contribute to elucidating possible gender differences in the effects of prenatal infection on 5-HT2A and mGlu2/3 receptor function. PMID:26051401

  1. THE SEROTONIN (5-HT) 5-HT2A RECEPTOR: ASSOCIATION WITH INHERENT AND COCAINE-EVOKED BEHAVIORAL DISINHIBITION IN RATS

    PubMed Central

    Anastasio, Noelle C.; Stoffel, Erin C.; Fox, Robert G.; Bubar, Marcy J.; Rice, Kenner C.; Moeller, F. Gerard; Cunningham, Kathryn A.

    2011-01-01

    Alterations in the balance of functional activity within the serotonin (5-HT) system are hypothesized to underlie impulse control. Cocaine-dependent subjects consistently demonstrate greater impulsivity relative to non-drug using control subjects. Preclinical studies suggest that the 5-HT2A receptor (5-HT2AR) contributes to the regulation of impulsive behavior and also mediates some of the behavioral effects of cocaine. We hypothesized that the selective 5-HT2AR antagonist M100907 would reduce inherent levels of impulsivity and attenuate impulsive responding induced by cocaine in two animal models of impulsivity, the differential reinforcement of low rate (DRL) task and the one-choice serial reaction time (1-CSRT) task. M100907 reduced rates of responding in the DRL task and premature responding in the 1-CSRT task. Conversely, cocaine disrupted rates of responding in the DRL task and increased premature responding in the 1-CSRT task. M100907 attenuated cocaine-induced increases in specific markers of behavioral disinhibition in the DRL and 1-CSRT tasks. These results suggest that the 5-HT2AR regulates inherent impulsivity, and that blockade of the 5-HT2AR alleviates specific aspects of elevated levels of impulsivity induced by cocaine exposure. These data point to the 5-HT2AR as an important regulatory substrate in impulse control. PMID:21499079

  2. Activation of 5-HT2a Receptors in the Basolateral Amygdala Promotes Defeat-Induced Anxiety and the Acquisition of Conditioned Defeat in Syrian Hamsters

    PubMed Central

    Clinard, Catherine T.; Bader, Lauren R.; Sullivan, Molly A.; Cooper, Matthew A.

    2014-01-01

    Conditioned defeat is a model in Syrian hamsters (Mesocricetus auratus) in which normal territorial aggression is replaced by increased submissive and defensive behavior following acute social defeat. The conditioned defeat response involves both a fear-related memory for a specific opponent as well as anxiety-like behavior indicated by avoidance of novel conspecifics. We have previously shown that systemic injection of a 5-HT2a receptor antagonist reduces the acquisition of conditioned defeat. Because neural activity in the basolateral amygdala (BLA) is critical for the acquisition of conditioned defeat and BLA 5-HT2a receptors can modulate anxiety but have a limited effect on emotional memories, we investigated whether 5-HT2a receptor modulation alters defeat-induced anxiety but not defeat-related memories. We injected the 5-HT2a receptor antagonist MDL 11,939 (0 mM, 1.7 mM or 17 mM) or the 5-HT2a receptor agonist TCB-2 (0 mM, 8 mM or 80 mM) into the BLA prior to social defeat. We found that injection of MDL 11,939 into the BLA impaired acquisition of the conditioned defeat response and blocked defeat-induced anxiety in the open field, but did not significantly impair avoidance of former opponents in the Y-maze. Furthermore, we found that injection of TCB-2 into the BLA increased the acquisition of conditioned defeat and increased anxiety-like behavior in the open field, but did not alter avoidance of former opponents. Our data suggest that 5-HT2a receptor signaling in the BLA is both necessary and sufficient for the development of conditioned defeat, likely via modulation of defeat-induced anxiety. PMID:25458113

  3. Genotype-Dependent Difference in 5-HT2C Receptor-Induced Hypolocomotion: Comparison with 5-HT2A Receptor Functional Activity

    PubMed Central

    Bazovkina, Darya V.; Kondaurova, Elena M.; Naumenko, Vladimir S.; Ponimaskin, Evgeni

    2015-01-01

    In the present study behavioral effects of the 5-HT2C serotonin receptor were investigated in different mouse strains. The 5-HT2C receptor agonist MK-212 applied intraperitoneally induced significant dose-dependent reduction of distance traveled in the open field test in CBA/Lac mice. This effect was receptor-specific because it was inhibited by the 5-HT2C receptor antagonist RS102221. To study the role of genotype in 5-HT2C receptor-induced hypolocomotion, locomotor activity of seven inbred mouse strains was measured after MK-212 acute treatment. We found that the 5-HT2C receptor stimulation by MK-212 decreased distance traveled in the open field test in CBA/Lac, C57Bl/6, C3H/He, and ICR mice, whereas it failed to affect locomotor activity in DBA/2J, Asn, and Balb/c mice. We also compared the interstrain differences in functional response to 5-HT2C and 5-HT2A receptors activation measured by the quantification of receptor-mediated head-twitches. These experiments revealed significant positive correlation between 5-HT2C and 5-HT2A receptors functional responses for all investigated mouse strains. Moreover, we found that 5-HT2A receptor activation with DOI did not change locomotor activity in CBA/Lac mice. Taken together, our data indicate the implication of 5-HT2C receptors in regulation of locomotor activity and suggest the shared mechanism for functional responses mediated by 5-HT2C and 5-HT2A receptors. PMID:26380122

  4. Genotype-Dependent Difference in 5-HT2C Receptor-Induced Hypolocomotion: Comparison with 5-HT2A Receptor Functional Activity.

    PubMed

    Bazovkina, Darya V; Kondaurova, Elena M; Naumenko, Vladimir S; Ponimaskin, Evgeni

    2015-01-01

    In the present study behavioral effects of the 5-HT2C serotonin receptor were investigated in different mouse strains. The 5-HT2C receptor agonist MK-212 applied intraperitoneally induced significant dose-dependent reduction of distance traveled in the open field test in CBA/Lac mice. This effect was receptor-specific because it was inhibited by the 5-HT2C receptor antagonist RS102221. To study the role of genotype in 5-HT2C receptor-induced hypolocomotion, locomotor activity of seven inbred mouse strains was measured after MK-212 acute treatment. We found that the 5-HT2C receptor stimulation by MK-212 decreased distance traveled in the open field test in CBA/Lac, C57Bl/6, C3H/He, and ICR mice, whereas it failed to affect locomotor activity in DBA/2J, Asn, and Balb/c mice. We also compared the interstrain differences in functional response to 5-HT2C and 5-HT2A receptors activation measured by the quantification of receptor-mediated head-twitches. These experiments revealed significant positive correlation between 5-HT2C and 5-HT2A receptors functional responses for all investigated mouse strains. Moreover, we found that 5-HT2A receptor activation with DOI did not change locomotor activity in CBA/Lac mice. Taken together, our data indicate the implication of 5-HT2C receptors in regulation of locomotor activity and suggest the shared mechanism for functional responses mediated by 5-HT2C and 5-HT2A receptors. PMID:26380122

  5. Genotype-Dependent Difference in 5-HT2C Receptor-Induced Hypolocomotion: Comparison with 5-HT2A Receptor Functional Activity.

    PubMed

    Bazovkina, Darya V; Kondaurova, Elena M; Naumenko, Vladimir S; Ponimaskin, Evgeni

    2015-01-01

    In the present study behavioral effects of the 5-HT2C serotonin receptor were investigated in different mouse strains. The 5-HT2C receptor agonist MK-212 applied intraperitoneally induced significant dose-dependent reduction of distance traveled in the open field test in CBA/Lac mice. This effect was receptor-specific because it was inhibited by the 5-HT2C receptor antagonist RS102221. To study the role of genotype in 5-HT2C receptor-induced hypolocomotion, locomotor activity of seven inbred mouse strains was measured after MK-212 acute treatment. We found that the 5-HT2C receptor stimulation by MK-212 decreased distance traveled in the open field test in CBA/Lac, C57Bl/6, C3H/He, and ICR mice, whereas it failed to affect locomotor activity in DBA/2J, Asn, and Balb/c mice. We also compared the interstrain differences in functional response to 5-HT2C and 5-HT2A receptors activation measured by the quantification of receptor-mediated head-twitches. These experiments revealed significant positive correlation between 5-HT2C and 5-HT2A receptors functional responses for all investigated mouse strains. Moreover, we found that 5-HT2A receptor activation with DOI did not change locomotor activity in CBA/Lac mice. Taken together, our data indicate the implication of 5-HT2C receptors in regulation of locomotor activity and suggest the shared mechanism for functional responses mediated by 5-HT2C and 5-HT2A receptors.

  6. Extensive Rigid Analogue Design Maps the Binding Conformation of Potent N-Benzylphenethylamine 5-HT2A Serotonin Receptor Agonist Ligands

    PubMed Central

    2012-01-01

    Based on the structure of the superpotent 5-HT2A agonist 2-(4-bromo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine, which consists of a ring-substituted phenethylamine skeleton modified with an N-benzyl group, we designed and synthesized a small library of constrained analogues to identify the optimal arrangement of the pharmacophoric elements of the ligand. Structures consisted of diversely substituted tetrahydroisoquinolines, piperidines, and one benzazepine. Based on the structure of (S,S)-9b, which showed the highest affinity of the series, we propose an optimal binding conformation. (S,S)-9b also displayed 124-fold selectivity for the 5-HT2A over the 5-HT2C receptor, making it the most selective 5-HT2A receptor agonist ligand currently known. PMID:23336049

  7. In Vivo Quantification of 5-HT2A Brain Receptors in Mdr1a KO Rats with 123I-R91150 Single-Photon Emission Computed Tomography.

    PubMed

    Dumas, Noé; Moulin-Sallanon, Marcelle; Fender, Pascal; Tournier, Benjamin B; Ginovart, Nathalie; Charnay, Yves; Millet, Philippe

    2015-01-01

    Our goal was to identify suitable image quantification methods to image 5-hydroxytryptamine2A (5-HT2A) receptors in vivo in Mdr1a knockout (KO) rats (i.e., P-glycoprotein KO) using 123I-R91150 single-photon emission computed tomography (SPECT). The 123I-R91150 binding parameters estimated with different reference tissue models (simplified reference tissue model [SRTM], Logan reference tissue model, and tissue ratio [TR] method) were compared to the estimates obtained with a comprehensive three-tissue/seven-parameter (3T/7k)-based model. The SRTM and Logan reference tissue model estimates of 5-HT2A receptor (5-HT2AR) nondisplaceable binding potential (BPND) correlated well with the absolute receptor density measured with the 3T/7k gold standard (r > .89). Quantification of 5-HT2AR using the Logan reference tissue model required at least 90 minutes of scanning, whereas the SRTM required at least 110 minutes. The TR method estimates were also highly correlated to the 5-HT2AR density (r > .91) and only required a single 20-minute scan between 100 and 120 minutes postinjection. However, a systematic overestimation of the BPND values was observed. The Logan reference tissue method is more convenient than the SRTM for the quantification of 5-HT2AR in Mdr1a KO rats using 123I-R91150 SPECT. The TR method is an interesting and simple alternative, despite its bias, as it still provides a valid index of 5-HT2AR density. PMID:26105563

  8. Lack of Association between the Serotonin Transporter (5-HTT) and Serotonin Receptor (5-HT2A) Gene Polymorphisms with Smoking Behavior among Malaysian Malays

    PubMed Central

    Rozak, Nur Iwani A; Ahmad, Imran; Gan, Siew Hua; Abu Bakar, Ruzilawati

    2014-01-01

    Abstract An insertion/deletion polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) and a polymorphism (rs6313) in the serotonin 2A receptor gene (5-HT2A) have previously been linked to smoking behavior. The objective of this study was to determine the possible association of the 5-HTTLPR and 5-HT2A gene polymorphisms with smoking behavior within a population of Malaysian male smokers (n=248) and non-smokers (n=248). The 5-HTTLPR genotypes were determined using the polymerase chain reaction (PCR) and were classified as short (S) alleles or long (L) alleles. The 5HT2A genotypes were determined using PCR-restriction fragment length polymorphisms (PCR-RFLP). No significant differences in the distribution frequencies of the alleles were found between the smokers and the non-smokers for the 5-HTTLPR polymorphism (x2 = 0.72, P>0.05) or the 5HT2A polymorphism (x2 = 0.73, P>0.05). This is the first study conducted on Malaysian Malay males regarding the association of 5-HTTLPR and 5HT2A polymorphisms and smoking behavior. However, the genes were not found to be associated with smoking behavior in our population. PMID:25853073

  9. Allosteric signaling through an mGlu2 and 5-HT2A heteromeric receptor complex and its potential contribution to schizophrenia.

    PubMed

    Moreno, José L; Miranda-Azpiazu, Patricia; García-Bea, Aintzane; Younkin, Jason; Cui, Meng; Kozlenkov, Alexey; Ben-Ezra, Ariel; Voloudakis, Georgios; Fakira, Amanda K; Baki, Lia; Ge, Yongchao; Georgakopoulos, Anastasios; Morón, José A; Milligan, Graeme; López-Giménez, Juan F; Robakis, Nikolaos K; Logothetis, Diomedes E; Meana, J Javier; González-Maeso, Javier

    2016-01-12

    Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) can form multiprotein complexes (heteromers), which can alter the pharmacology and functions of the constituent receptors. Previous findings demonstrated that the Gq/11-coupled serotonin 5-HT2A receptor and the Gi/o-coupled metabotropic glutamate 2 (mGlu2) receptor-GPCRs that are involved in signaling alterations associated with psychosis-assemble into a heteromeric complex in the mammalian brain. In single-cell experiments with various mutant versions of the mGlu2 receptor, we showed that stimulation of cells expressing mGlu2-5-HT2A heteromers with an mGlu2 agonist led to activation of Gq/11 proteins by the 5-HT2A receptors. For this crosstalk to occur, one of the mGlu2 subunits had to couple to Gi/o proteins, and we determined the relative location of the Gi/o-contacting subunit within the mGlu2 homodimer of the heteromeric complex. Additionally, mGlu2-dependent activation of Gq/11, but not Gi/o, was reduced in the frontal cortex of 5-HT2A knockout mice and was reduced in the frontal cortex of postmortem brains from schizophrenic patients. These findings offer structural insights into this important target in molecular psychiatry.

  10. Functional selectivity of hallucinogenic phenethylamine and phenylisopropylamine derivatives at human 5-hydroxytryptamine (5-HT)2A and 5-HT2C receptors.

    PubMed

    Moya, Pablo R; Berg, Kelly A; Gutiérrez-Hernandez, Manuel A; Sáez-Briones, Patricio; Reyes-Parada, Miguel; Cassels, Bruce K; Clarke, William P

    2007-06-01

    2,5-Dimethoxy-4-substituted phenylisopropylamines and phenethylamines are 5-hydroxytryptamine (serotonin) (5-HT)(2A/2C) agonists. The former are partial to full agonists, whereas the latter are partial to weak agonists. However, most data come from studies analyzing phospholipase C (PLC)-mediated responses, although additional effectors [e.g., phospholipase A(2) (PLA(2))] are associated with these receptors. We compared two homologous series of phenylisopropylamines and phenethylamines measuring both PLA(2) and PLC responses in Chinese hamster ovary-K1 cells expressing human 5-HT(2A) or 5-HT(2C) receptors. In addition, we assayed both groups of compounds as head shake inducers in rats. At the 5-HT(2C) receptor, most compounds were partial agonists for both pathways. Relative efficacy of some phenylisopropylamines was higher for both responses compared with their phenethylamine counterparts, whereas for others, no differences were found. At the 5-HT(2A) receptor, most compounds behaved as partial agonists, but unlike findings at 5-HT(2C) receptors, all phenylisopropylamines were more efficacious than their phenethylamine counterparts. 2,5-Dimethoxyphenylisopropylamine activated only the PLC pathway at both receptor subtypes, 2,5-dimethoxyphenethylamine was selective for PLC at the 5-HT(2C) receptor, and 2,5-dimethoxy-4-nitrophenethylamine was PLA(2)-specific at the 5-HT(2A) receptor. For both receptors, the rank order of efficacy of compounds differed depending upon which response was measured. The phenylisopropylamines were strong head shake inducers, whereas their phenethylamine congeners were not, in agreement with in vitro results and the involvement of 5-HT(2A) receptors in the head shake response. Our results support the concept of functional selectivity and indicate that subtle changes in ligand structure can result in significant differences in the cellular signaling profile.

  11. APD125, a Selective Serotonin 5-HT2A Receptor Inverse Agonist, Significantly Improves Sleep Maintenance in Primary Insomnia

    PubMed Central

    Rosenberg, Russell; Seiden, David J.; Hull, Steven G.; Erman, Milton; Schwartz, Howard; Anderson, Christen; Prosser, Warren; Shanahan, William; Sanchez, Matilde; Chuang, Emil; Roth, Thomas

    2008-01-01

    Introduction: Insomnia is a condition affecting 10% to 15% of the adult population and is characterized by difficulty falling asleep, difficulty staying asleep, or nonrestorative sleep, accompanied by daytime impairment or distress. This study evaluates APD125, a selective inverse agonist of the 5-HT2A receptor, for treatment of chronic insomnia, with particular emphasis on sleep maintenance. In phase 1 studies, APD125 improved sleep maintenance and was well tolerated. Methodology: Adult subjects (n = 173) with DSM-IV defined primary insomnia were randomized into a multicenter, double-blind, placebo-controlled, 3-way crossover study to compare 2 doses of APD125 (10 mg and 40 mg) with placebo. Each treatment period was 7 days with a 7- to 9-day washout period between treatments. Polysomnographic recordings were performed at the initial 2 screening nights and at nights (N) 1/2 and N 6/7 of each treatment period. Results: APD125 was associated with significant improvements in key sleep maintenance parameters measured by PSG. Wake time after sleep onset decreased (SEM) by 52.5 (3.2) min (10 mg) and 53.5 (3.5) min (40 mg) from baseline to N 1/2 vs. 37.8 (3.4) min for placebo, (P < 0.0001 for both doses vs placebo), and by 51.7 (3.4) min (P = 0.01) and 48.0 (3.6) min (P = 0.2) at N 6/7 vs. 44.0 (3.8) min for placebo. Significant APD125 effects on wake time during sleep were also seen (P < 0.0001 N 1/2, P < 0.001 N 6/7). The number of arousals and number of awakenings decreased significantly with APD125 treatment compared to placebo. Slow wave sleep showed a statistically significant dose-dependent increase. There was no significant decrease in latency to persistent sleep. No serious adverse events were reported, and no meaningful differences in adverse event profiles were observed between either dose of APD125 and placebo. APD125 was not associated with next-day psychomotor impairment as measured by Digit Span, Digit Symbol Copy, and Digit Symbol Coding Tests

  12. Involvement of 5-HT2A receptors in MDMA reinforcement and cue-induced reinstatement of MDMA-seeking behaviour.

    PubMed

    Orejarena, María Juliana; Lanfumey, Laurence; Maldonado, Rafael; Robledo, Patricia

    2011-08-01

    The serotonergic system appears crucial for (±)-3,4-methylenedioxymethamphetamine (MDMA) reinforcing properties. Current evidence indicates that serotonin 5-HT2A receptors (5-HT2ARs) modulate mesolimbic dopamine (DA) activity and several behavioural responses related to the addictive properties of psychostimulants. This study evaluated the role of 5-HT2ARs in MDMA-induced reinforcement and hyperlocomotion, and the reinstatement of MDMA-seeking behaviour. Basal and MDMA-stimulated extracellular levels of DA in the nucleus accumbens (NAc) and serotonin and noradrenaline in the prefrontal cortex were also assessed. Self-administration of MDMA was blunted in 5-HT2AR knockout (KO) mice compared to wild-type (WT) littermates at both doses tested (0.125 and 0.25 mg/kg per infusion). Horizontal locomotion was increased by MDMA (10 and 20 mg/kg i.p.) to a higher extent in KO than in WT mice. DA outflow in the NAc was lower in KO compared to WT mice under basal conditions and after MDMA (20 mg/kg) challenge. In WT mice, MDMA (5 and 10 mg/kg i.p.) priming did not reinstate MDMA-seeking behaviour, while cue-induced reinstatement was prominent. This cue-induced reinstatement was blocked by administration of the selective 5-HT2AR antagonist, SR46349B (eplivanserin) at a dose of 0.5 mg/kg, but not at 0.25 mg/kg. Our results indicate that 5-HT2ARs are crucial for MDMA-induced reinforcement and cue-induced reinstatement of MDMA-seeking behaviour. These effects are probably due to the modulation of mesolimbic dopaminergic activity.

  13. 3,4-methylenedioxymethamphetamine increases excitability in the dentate gyrus: role of 5HT2A receptor-induced PGE2 signaling.

    PubMed

    Collins, Stuart A; Huff, Courtney; Chiaia, Nicolas; Gudelsky, Gary A; Yamamoto, Bryan K

    2016-03-01

    3,4-methylenedioxymethamphetamine (MDMA) is a widely abused psychostimulant, which causes release of serotonin in various forebrain regions. Recently, we reported that MDMA increases extracellular glutamate concentrations in the dentate gyrus, via activation of 5HT2A receptors. We examined the role of prostaglandin signaling in mediating the effects of 5HT2A receptor activation on the increases in extracellular glutamate and the subsequent long-term loss of parvalbumin interneurons in the dentate gyrus caused by MDMA. Administration of MDMA into the dentate gyrus of rats increased PGE2 concentrations which was prevented by coadministration of MDL100907, a 5HT2A receptor antagonist. MDMA-induced increases in extracellular glutamate were inhibited by local administration of SC-51089, an inhibitor of the EP1 prostaglandin receptor. Systemic administration of SC-51089 during injections of MDMA prevented the decreases in parvalbumin interneurons observed 10 days later. The loss of parvalbumin immunoreactivity after MDMA exposure coincided with a decrease in paired-pulse inhibition and afterdischarge threshold in the dentate gyrus. These changes were prevented by inhibition of EP1 and 5HT2A receptors during MDMA. Additional experiments revealed an increased susceptibility to kainic acid-induced seizures in MDMA-treated rats, which could be prevented with SC51089 treatments during MDMA exposure. Overall, these findings suggest that 5HT2A receptors mediate MDMA-induced PGE2 signaling and subsequent increases in glutamate. This signaling mediates parvalbumin cell losses as well as physiologic changes in the dentate gyrus, suggesting that the lack of the inhibition provided by these neurons increases the excitability within the dentate gyrus of MDMA-treated rats. We hypothesized that the widely abused psychostimulant MDMA causes a loss of parvalbumin (PV) cells and increases excitability in the dentate gyrus. MDMA increases serotonin (5HT) release and activates 5HT2A

  14. Tolerance to LSD and DOB induced shaking behaviour: differential adaptations of frontocortical 5-HT(2A) and glutamate receptor binding sites.

    PubMed

    Buchborn, Tobias; Schröder, Helmut; Dieterich, Daniela C; Grecksch, Gisela; Höllt, Volker

    2015-03-15

    Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD) and dimethoxy-bromoamphetamine (DOB), provoke stereotype-like shaking behaviour in rodents, which is hypothesised to engage frontocortical glutamate receptor activation secondary to serotonin2A (5-HT2A) related glutamate release. Challenging this hypothesis, we here investigate whether tolerance to LSD and DOB correlates with frontocortical adaptations of 5-HT2A and/or overall-glutamate binding sites. LSD and DOB (0.025 and 0.25 mg/kg, i.p.) induce a ketanserin-sensitive (0.5 mg/kg, i.p., 30-min pretreatment) increase in shaking behaviour (including head twitches and wet dog shakes), which with repeated application (7× in 4 ds) is undermined by tolerance. Tolerance to DOB, as indexed by DOB-sensitive [(3)H]spiroperidol and DOB induced [(35)S]GTP-gamma-S binding, is accompanied by a frontocortical decrease in 5-HT2A binding sites and 5-HT2 signalling, respectively; glutamate-sensitive [(3)H]glutamate binding sites, in contrast, remain unchanged. As to LSD, 5-HT2 signalling and 5-HT2A binding, respectively, are not or only marginally affected, yet [(3)H]glutamate binding is significantly decreased. Correlation analysis interrelates tolerance to DOB to the reduced 5-HT2A (r=.80) as well as the unchanged [(3)H]glutamate binding sites (r=.84); tolerance to LSD, as opposed, shares variance with the reduction in [(3)H]glutamate binding sites only (r=.86). Given that DOB and LSD both induce tolerance, one correlating with 5-HT2A, the other with glutamate receptor adaptations, it might be inferred that tolerance can arise at either level. That is, if a hallucinogen (like LSD in our study) fails to induce 5-HT2A (down-)regulation, glutamate receptors (activated postsynaptic to 5-HT2A related glutamate release) might instead adapt and thus prevent further overstimulation of the cortex. PMID:25513973

  15. Tolerance to LSD and DOB induced shaking behaviour: differential adaptations of frontocortical 5-HT(2A) and glutamate receptor binding sites.

    PubMed

    Buchborn, Tobias; Schröder, Helmut; Dieterich, Daniela C; Grecksch, Gisela; Höllt, Volker

    2015-03-15

    Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD) and dimethoxy-bromoamphetamine (DOB), provoke stereotype-like shaking behaviour in rodents, which is hypothesised to engage frontocortical glutamate receptor activation secondary to serotonin2A (5-HT2A) related glutamate release. Challenging this hypothesis, we here investigate whether tolerance to LSD and DOB correlates with frontocortical adaptations of 5-HT2A and/or overall-glutamate binding sites. LSD and DOB (0.025 and 0.25 mg/kg, i.p.) induce a ketanserin-sensitive (0.5 mg/kg, i.p., 30-min pretreatment) increase in shaking behaviour (including head twitches and wet dog shakes), which with repeated application (7× in 4 ds) is undermined by tolerance. Tolerance to DOB, as indexed by DOB-sensitive [(3)H]spiroperidol and DOB induced [(35)S]GTP-gamma-S binding, is accompanied by a frontocortical decrease in 5-HT2A binding sites and 5-HT2 signalling, respectively; glutamate-sensitive [(3)H]glutamate binding sites, in contrast, remain unchanged. As to LSD, 5-HT2 signalling and 5-HT2A binding, respectively, are not or only marginally affected, yet [(3)H]glutamate binding is significantly decreased. Correlation analysis interrelates tolerance to DOB to the reduced 5-HT2A (r=.80) as well as the unchanged [(3)H]glutamate binding sites (r=.84); tolerance to LSD, as opposed, shares variance with the reduction in [(3)H]glutamate binding sites only (r=.86). Given that DOB and LSD both induce tolerance, one correlating with 5-HT2A, the other with glutamate receptor adaptations, it might be inferred that tolerance can arise at either level. That is, if a hallucinogen (like LSD in our study) fails to induce 5-HT2A (down-)regulation, glutamate receptors (activated postsynaptic to 5-HT2A related glutamate release) might instead adapt and thus prevent further overstimulation of the cortex.

  16. A comparison of the behavioural effects of 5-HT2A and 5-HT2C receptor agonists in the pigeon.

    PubMed

    Wolff, M C; Leander, J D

    2000-08-01

    Activity at the 5-HT2A receptor versus that of the 5-HT2C receptor was studied in three behavioural paradigms. In pigeons trained to discriminate 0.32 mg/kg of 1-(2,5-diemethoxy-4-iodophenyl)-2-aminopropane (DOI) (a mixed 5-HT2A/C receptor agonist) from vehicle, quipazine (0.1-1 mg/kg) and m-chlorophenylpiperazine (mCPP) (1-3 mg/kg) substituted for DOI in a dose-related manner, and this generalization was blocked by MDL100907 (0.0001-0.01 mg/kg), a selective 5-HT2A receptor antagonist. RO60-0175 (a relatively selective 5-HT2C agonist) induced partial substitution at 3 mg/kg that was antagonized by both MDL100907 and by 3 mg/kg of SB242084, a relatively selective 5-HT2C antagonist. MK212 (a mixed 5-HT2C/A agonist) induced partial substitution that was antagonized by SB242084, but not by MDL100907. On a progressive ratio 5 operant schedule (PR5) for food reinforcement, DOI, quipazine, mCPP, MK212 and R060-0175 decreased the break point; mCPP, DOI, MK212 and quipazine also induced vomiting. Although MDL100907 antagonized both the reductions of break point and vomiting, SB242084 only partially attenuated the decrease in break point observed with MK212 and DOI, and was unable to eliminate vomiting. Thus pharmacological activity at the 5-HT2A receptor can be behaviourally distinguished from pharmacological activity at the 5-HT2C receptor in the pigeon. Furthermore, the decrease in the break point of a PR5 schedule induced by 5-HT2C receptor agonists may be related to decreased appetite, whereas that induced by 5-HT2A receptor agonists may be due to unrelated factors, such as emesis. PMID:11103887

  17. The role of the 5-HT2A and 5-HT2C receptors in the stimulus effects of hallucinogenic drugs. I: Antagonist correlation analysis.

    PubMed

    Fiorella, D; Rabin, R A; Winter, J C

    1995-10-01

    Investigations conducted over the past 3 decades have demonstrated that serotonergic receptors, specifically the 5-HT2A and 5-HT2C subtypes, play an important role in the behavioral effects of hallucinogenic compounds. The present study was designed to determine the respective significance of these two receptors in the stimulus effects of LSD and (-)DOM in the rat. Specifically, the interactions of a series of serotonergic antagonists (risperidone, pirenpirone, metergoline, ketanserin, loxapine, LY53857, pizotyline, spiperone, cyprohepatadine, mesulergine, promethazine, and thioridazine) with the LSD stimulus and the (-)DOM stimulus in LSD-trained subjects was defined. From these data, IC50 values were determined for the inhibition of the LSD-appropriate responding elicited by either 0.1 mg/kg LSD (15-min pretreatment time) or 0.4 mg/kg (-)DOM (75-min pretreatment). In addition, the affinities of these antagonists for 5-HT2A and 5-HT2C receptors were determined in radioligand competition studies, 5-HT2A affinity correlated significantly with IC50 values for the blockade of the LSD (r = +0.75, P < 0.05) and (-)DOM (r = +0.95, P < 0.001) stimuli in the LSD trained subjects. 5-HT2C affinity did not correlate significantly with either series of IC50 values. These data indicate that (1) the stimulus effects of LSD, and (2) the substitution of (-)DOM for the LSD stimulus are mediated by agonist activity at 5-HT2A receptors.

  18. Effect of fluvoxamine on platelet 5-HT2A receptors as studied by [3H]lysergic acid diethylamide ([3H]LSD) binding in healthy volunteers.

    PubMed

    Spigset, O; Mjörndal, T

    1997-09-01

    Alterations in platelet 5-HT2A receptor characteristics have been reported in major depression as well as in other psychiatric diseases, and some effort has been made to utilize platelet 5-HT2A receptor status as a biological correlate to antidepressant drug response. In order to investigate whether treatment with a selective serotonin reuptake inhibitor affects platelet 5-HT2A receptors, we have studied platelet [3H]lysergic acid diethylamide ([3H]LSD) binding in healthy subjects treated with fluvoxamine in increasing dosage once weekly for 4 weeks. After 1 week of fluvoxamine treatment (25 mg/day), both Bmax and Kd were significantly lower than before the start of the treatment (19.9 versus 25.5 fmol/mg protein, P = 0.005 for Bmax; 0.45 versus 0.93 nM, P = 0.006 for Kd). Bmax returned to baseline during week 2, whereas Kd was lower than the baseline value throughout the treatment period. After discontinuation of fluvoxamine treatment, there was a significant increase in Kd (0.50 nM before discontinuation vs. 1.14 nM after discontinuation; P = 0.001), but not in Bmax. The study demonstrates that fluvoxamine affects platelet 5-HT2A receptor status irrespective of underlying psychiatric disease, and that this effect is evident already after 1 week at a subtherapeutic fluvoxamine dose.

  19. Exploring the relationship between binding modes of 9-(aminomethyl)-9,10-dihydroanthracene and cyproheptadine analogues at the 5-HT2A serotonin receptor.

    PubMed

    Westkaemper, R B; Runyon, S P; Savage, J E; Roth, B L; Glennon, R A

    2001-02-26

    Comparison of the serotonin 5-HT2A receptor affinities of a parallel series of structural analogues of the novel ligand 9-aminomethyl-9,10-dihydroanthracene (AMDA) and a structurally similar prototypical tricyclic amine cyproheptadine suggests that the two agents bind to the receptor in different fashions. Examination of ligand-receptor model complexes supports the experimental data and suggests a potential origin for the differences in binding modes.

  20. MDMA-induced loss of parvalbumin interneurons within the dentate gyrus is mediated by 5HT2A and NMDA receptors.

    PubMed

    Collins, Stuart A; Gudelsky, Gary A; Yamamoto, Bryan K

    2015-08-15

    MDMA is a widely abused psychostimulant which causes a rapid and robust release of the monoaminergic neurotransmitters dopamine and serotonin. Recently, it was shown that MDMA increases extracellular glutamate concentrations in the dorsal hippocampus, which is dependent on serotonin release and 5HT2A/2C receptor activation. The increased extracellular glutamate concentration coincides with a loss of parvalbumin-immunoreactive (PV-IR) interneurons of the dentate gyrus region. Given the known susceptibility of PV interneurons to excitotoxicity, we examined whether MDMA-induced increases in extracellular glutamate in the dentate gyrus are necessary for the loss of PV cells in rats. Extracellular glutamate concentrations increased in the dentate gyrus during systemic and local administration of MDMA. Administration of the NMDA receptor antagonist, MK-801, during systemic injections of MDMA, prevented the loss of PV-IR interneurons seen 10 days after MDMA exposure. Local administration of MDL100907, a selective 5HT2A receptor antagonist, prevented the increases in glutamate caused by reverse dialysis of MDMA directly into the dentate gyrus and prevented the reduction of PV-IR. These findings provide evidence that MDMA causes decreases in PV within the dentate gyrus through a 5HT2A receptor-mediated increase in glutamate and subsequent NMDA receptor activation.

  1. Development of a Multiplex Assay for Studying Functional Selectivity of Human Serotonin 5-HT2A Receptors and Identification of Active Compounds by High-Throughput Screening.

    PubMed

    Iglesias, Alba; Lage, Sonia; Cadavid, Maria Isabel; Loza, Maria Isabel; Brea, José

    2016-09-01

    G protein-coupled receptors (GPCRs) exist as collections of conformations in equilibrium, and the efficacy of drugs has been proposed to be associated with their absolute and relative affinities for these different conformations. The serotonin 2A (5-HT2A) receptor regulates multiple physiological functions, is involved in the pathophysiology of schizophrenia, and serves as an important target of atypical antipsychotic drugs. This receptor was one of the first GPCRs for which the functional selectivity phenomenon was observed, with its various ligands exerting differential effects on the phospholipase A2 (PLA2) and phospholipase C (PLC) signaling pathways. We aimed to develop a multiplex functional assay in 96-well plates for the simultaneous measurement of the PLA2 and PLC pathways coupled to 5-HT2A receptors; this approach enables the detection of either functional selectivity or cooperativity phenomena in early drug screening stages. The suitability of the method for running screening campaigns was tested using the Prestwick Chemical Library, and 22 confirmed hits with activities of more than 90% were identified; 11 of these hits produced statistically significant differences between the two effector pathways. Thus, we have developed a miniaturized multiplex assay in 96-well plates to measure functional selectivity for 5-HT2A receptors in the early stages of the drug discovery process. PMID:27095818

  2. Synthesis and in vitro evaluation of [18F]FECIMBI-36: A potential agonist PET ligand for 5-HT2A/2C receptors

    PubMed Central

    Prabhakaran, Jaya; Underwood, Mark D.; Dileep Kumar, J. S.; Simpson, Norman R.; Kassir, Suham A.; Bakalian, Mihran J.; Mann, J. John; Arango, Victoria

    2016-01-01

    Radiosynthesis and in vitro evaluation of [18F]-2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-(2-fluoroethoxy)benzyl)ethanamine, ([18F]FECIMBI-36) or ([18F]1), a potential agonist PET imaging agent for 5-HT2A/2C receptors is described. Syntheses of reference standard 1 and the corresponding des-fluoroethyl radiolabeling precursor (2) were achieved with 75% and 65% yields, respectively. In vitro pharmacology assay of FECIMBI-36 by [3H]-ketanserin competition binding assay obtained from NIMH-PDSP showed high affinities to 5-HT2AR (Ki = 1 nM) and 5-HT2CR (Ki = 1.7 nM). Radiolabeling of FECIMBI-36 was achieved from the boc-protected precursor 2 using [18F]-fluoroethyltosylate in presence of Cs2CO3 in DMSO followed by removal of the protective group. [18F]1 was isolated using RP-HPLC in 25 ± 5% yield, purity ≥95% and specific activity 1–2 Ci/μmol (N = 6). In vitro autoradiography studies demonstrate that [18F]1 selectively label 5-HT2A and 5-HT2C receptors in slide-mounted sections of postmortem human brain using phosphor imaging. Our results indicate the potential of [18F]1 for imaging 5-HT2A/2C receptors in the high affinity state in vivo using PET imaging. PMID:26253634

  3. Synthesis and in vitro evaluation of [18F]FECIMBI-36: A potential agonist PET ligand for 5-HT2A/2C receptors.

    PubMed

    Prabhakaran, Jaya; Underwood, Mark D; Kumar, J S Dileep; Simpson, Norman R; Kassir, Suham A; Bakalian, Mihran J; Mann, J John; Arango, Victoria

    2015-09-15

    Radiosynthesis and in vitro evaluation of [(18)F]-2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-(2-fluoroethoxy)benzyl)ethanamine, ([(18)F]FECIMBI-36) or ([(18)F]1), a potential agonist PET imaging agent for 5-HT2A/2C receptors is described. Syntheses of reference standard 1 and the corresponding des-fluoroethyl radiolabeling precursor (2) were achieved with 75% and 65% yields, respectively. In vitro pharmacology assay of FECIMBI-36 by [(3)H]-ketanserin competition binding assay obtained from NIMH-PDSP showed high affinities to 5-HT2AR (Ki = 1nM) and 5-HT2CR (Ki=1.7 nM). Radiolabeling of FECIMBI-36 was achieved from the boc-protected precursor 2 using [(18)F]-fluoroethyltosylate in presence of Cs2CO3 in DMSO followed by removal of the protective group. [(18)F]1 was isolated using RP-HPLC in 25 ± 5% yield, purity > 95% and specific activity 1-2Ci/μmol (N = 6). In vitro autoradiography studies demonstrate that [(18)F]1 selectively label 5-HT2A and 5-HT2C receptors in slide-mounted sections of postmortem human brain using phosphor imaging. Our results indicate the potential of [(18)F]1 for imaging 5-HT2A/2C receptors in the high affinity state in vivo using PET imaging.

  4. Role of 5-HT2A and 5-HT2C receptors in the stimulus effects of hallucinogenic drugs. II: Reassessment of LSD false positives.

    PubMed

    Fiorella, D; Rabin, R A; Winter, J C

    1995-10-01

    In the context of animal studies of hallucinogens, an LSD-false positive is defined as a drug known to be devoid of hallucinogenic activity in humans but which nonetheless fully mimics LSD in animals. Quipazine, MK-212, lisuride, and yohimbine have all been reported to be LSD false positives. The present study was designed to determine whether these compounds also substitute for the stimulus effects of the more pharmacologically selective hallucinogen (-)DOM (0.56 mg/kg, 75-min pretreatment time). The LSD and (-)DOM stimuli fully generalized to quipazine (3.0 mg/kg) and lisuride (0.2 mg/kg), but only partially generalized to MK-212 (0.1-1.0 mg/kg) and yohimbine (2-20 mg/kg). In combination tests, pirenpirone (0.08 mg/kg), a compound with both D2 and 5-HT2A affinity, blocked the substitution of quipazine and lisuride for the (-)DOM stimulus. Ketanserin (2.5 mg/kg), an antagonist with greater than 1 order of magnitude higher affinity for 5-HT2A receptors than either 5-HT2C or D2 receptors, also fully blocked the substitution of these compounds for the (-)DOM stimulus, while the selective D2 antagonist thiothixene (0.1-1.0 mg/kg) failed to block the substitution of lisuride for the (-)DOM stimulus. These results suggest that quipazine and lisuride substitute for the stimulus properties of the phenylalkglamine hallucinogen (-)DOM via agonist activity at 5-HT2A receptors. In addition, these results suggest that 5-HT2A agonist activity may be required, but is not in itself sufficient, for indolamine and phenylalkglamine compounds to elicit hallucinations in humans. Finally, it is concluded that MK-212 and yohimbine are neither LSD nor (-)DOM false positives.

  5. Implication of 5-HT2A subtype receptors in DOI activity in the four-plates test-retest paradigm in mice.

    PubMed

    Ripoll, Nadège; Hascoët, Martine; Bourin, Michel

    2006-01-01

    The four-plates test (FPT) is an animal model of anxiety which allows the detection of anxiolytic effect not only of benzodiazepines (BZDs) but also of other non-BZDs anxiolytic compounds such as antidepressants (ADs). Furthermore, DOI, a 5-HT(2A/2C) agonist, has been shown to exert an anxiolytic-like effect in this model. Retesting mice in animal models of anxiety (test-retest paradigm) induces an anxiogenic-like and a loss of anxiolytic-like effects in response to BZDs and ADs. On the contrary, DOI has been reported to oppose the fear potentiation induced by trial 1 in the FPT. Despite DOI is considered as one of the most selective 5-HT(2A) available, it acts as agonist at all three 5-HT(2) receptor subtypes (5-HT(2A), 5-HT(2B) and 5-HT(2C)). The aim of this study was thus to investigate in the FPT test-retest paradigm, which 5-HT(2) receptor subtype(s) was involved in the DOI-induced effect in experienced mice. The effect of DOI (0.25-4 mg/kg) and the agonists, 5-HT(2B), BW 723C86 (1-16 mg/kg) and 5-HT(2C), RO 60-0175 (0.25-4 mg/kg) have also been studied. Then, antagonism studies were conducted combinating the 5-HT(2A) receptor antagonist SR 46349B, the 5-HT(2B/2C) receptor antagonist SB 206553 or the selective 5-HT(2C) receptor antagonist RS 10-2221 (at the doses of 0.1 and 1 mg/kg) with the DOI (1 mg/kg). Our study shows that the BW 723C86 had no effect on retesting mice, whereas it exerted an anxiolytic-like effect in naive mice. By contrast to DOI, the RO 60-0175 had no effect neither in naive nor experienced mice. Furthermore, only the SR 46349B antagonized the DOI-induced anti-punishment effect. Diazepam included as a positive control also increased in each case the number of punished passages in naive mice. Our findings altogether also suggest that DOI exerts its anxiolytic-like effect in the FPT test-retest paradigm through 5-HT(2A) receptors.

  6. Participation of 5-HT1-like and 5-HT2A receptors in the contraction of human temporal artery by 5-hydroxytryptamine and related drugs.

    PubMed Central

    Verheggen, R.; Freudenthaler, S.; Meyer-Dulheuer, F.; Kaumann, A. J.

    1996-01-01

    1. We investigated the hypothesis that, as in some other large human arteries, 5-HT-induced contraction of the temporal artery is mediated through two co-existing receptor populations, 5-HT1-like- and 5-HT2A. Temporal arterial segments were obtained from patients undergoing brain surgery and rings prepared set up to contract with 5-HT and related agents. Fractions of maximal 5-HT responses mediated through 5-HT1-like and 5-HT2A receptors, f1 and f2 = 1-f1, were estimated by use of the 5-HT2A-selective antagonist ketanserin. 2. In rings with intact endothelium 5-HT evoked contractions with a -log EC50, M of 7.0. Ketanserin (10-1000 nM) antagonized part of the 5-HT-induced contractions. Ketanserin-resistant components of 5-HT-induced contractions were found with -log EC50, M of 6.9 and f1 of 0.17 (100 nM ketanserin) and -log EC50, M of 6.4 and f1 of 0.20 (1000 nM ketanserin). 3. In rings with endothelial function attenuated by enzymatic treatment, 5-HT caused contractions with a -log EC50, M of 7.2 that were partially blocked by ketanserin. Ketanserin-resistant components of 5-HT-induced contractions were found with -log EC50, M 7.4 and f1 of 0.16 (100 nM ketanserin) and -log EC50, M of 7.5 and f1 of 0.14 (1000 nM ketanserin). 4. The ketanserin-resistant component of 5-HT-evoked contraction was blocked by methiothepin (100-1000 nM) consistent with mediation through 5-HT1-like receptors. 5. In rings with intact endothelium the 5-HT1-like-selective agonist, sumatriptan, caused small contractions with a -log EC50, M of 6.5 and intrinsic activity of 0.21 with respect to 5-HT that were resistant to blockade by 1000 nM ketanserin but antagonized by 100 nM methiothepin. 6. In rings with intact endothelium the 5-HT2A receptor partial agonist SK&F 103829 (2,3,4,5-tetrahydro-8[methyl sulphonyl]-1H3-benzazepin-7-ol methensulphonate) contracted rings with a -log EC50, M of 5.0 and an intrinsic activity of 0.49 with respect to 5-HT; the effects were antagonized by ketanserin 1000

  7. Evidence for a 5-HT2A receptor mode of action in the anxiolytic-like properties of DOI in mice.

    PubMed

    Nic Dhonnchadha, Bríd Aine; Hascoët, Martine; Jolliet, Pascale; Bourin, Michel

    2003-12-17

    DOI [(+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane] displays a high affinity for the rat 5-HT2A, 5-HT2B and 5-HT2C receptors (pKi 7.3, 7.4 and 7.8, respectively) and acts as an agonist. DOI (0.5-4 mg/kg, i.p. 30 min pre-test) increased the number of punished passages in the mouse four plates test (FPT). The anti-punishment action of DOI (1 mg/kg, i.p. 30 min pre-test) was abolished by prior treatment with the selective 5-HT2A receptor antagonist SR 46949B (0.1 and 1 mg/kg, i.p. 45 min pre-test) but not by the selective 5-HT2C receptor antagonist RS 10-2221 (0.1 and 1 mg/kg, i.p. 45 min pre-test) nor the selective 5-HT2C/2B receptor antagonist SB 206553 (0.1 and 1 mg/kg, i.p. 45 min pre-test). An anxiolytic-like action was also observed for DOI (1 mg/kg) in the elevated plus maze (EPM). The anxiolytic-like action of DOI (1 mg/kg, i.p. 30 min pre-test) was antagonised by pre-treatment with SR 46949B (0.125 and 0.5 mg/kg, i.p. 45 min pre-test) but not by RS 10-2221 (0.1 and 1 mg/kg, i.p. 45 min pre-test) nor SB 206553 (0.1 and 1 mg/kg, i.p. 45 min pre-test). In conclusion, DOI produced an anxiolytic-like profile in the mouse FPT and EPM. These effects are likely to be 5-HT2A receptor mediated.

  8. A Model of Post-Infection Fatigue Is Associated with Increased TNF and 5-HT2A Receptor Expression in Mice.

    PubMed

    Couch, Yvonne; Xie, Qin; Lundberg, Louise; Sharp, Trevor; Anthony, Daniel C

    2015-01-01

    It is well documented that serotonin (5-HT) plays an important role in psychiatric illness. For example, myalgic encephalomyelitis (ME/CFS), which is often provoked by infection, is a disabling illness with an unknown aetiology and diagnosis is based on symptom-specific criteria. However, 5-HT2A receptor expression and peripheral cytokines are known to be upregulated in ME. We sought to examine the relationship between the 5-HT system and cytokine expression following systemic bacterial endotoxin challenge (LPS, 0.5 mg/kg i.p.), at a time when the acute sickness behaviours have largely resolved. At 24 hours post-injection mice exhibit no overt changes in locomotor behaviour, but do show increased immobility in a forced swim test, as well as decreased sucrose preference and reduced marble burying activity, indicating a depressive-like state. While peripheral IDO activity was increased after LPS challenge, central activity levels remained stable and there was no change in total brain 5-HT levels or 5-HIAA/5-HT. However, within the brain, levels of TNF and 5-HT2A receptor mRNA within various regions increased significantly. This increase in receptor expression is reflected by an increase in the functional response of the 5-HT2A receptor to agonist, DOI. These data suggest that regulation of fatigue and depressive-like moods after episodes of systemic inflammation may be regulated by changes in 5-HT receptor expression, rather than by levels of enzyme activity or cytokine expression in the CNS. PMID:26147001

  9. A Model of Post-Infection Fatigue Is Associated with Increased TNF and 5-HT2A Receptor Expression in Mice

    PubMed Central

    Couch, Yvonne; Xie, Qin; Lundberg, Louise; Sharp, Trevor; Anthony, Daniel C.

    2015-01-01

    It is well documented that serotonin (5-HT) plays an important role in psychiatric illness. For example, myalgic encephalomyelitis (ME/CFS), which is often provoked by infection, is a disabling illness with an unknown aetiology and diagnosis is based on symptom-specific criteria. However, 5-HT2A receptor expression and peripheral cytokines are known to be upregulated in ME. We sought to examine the relationship between the 5-HT system and cytokine expression following systemic bacterial endotoxin challenge (LPS, 0.5mg/kg i.p.), at a time when the acute sickness behaviours have largely resolved. At 24 hours post-injection mice exhibit no overt changes in locomotor behaviour, but do show increased immobility in a forced swim test, as well as decreased sucrose preference and reduced marble burying activity, indicating a depressive-like state. While peripheral IDO activity was increased after LPS challenge, central activity levels remained stable and there was no change in total brain 5-HT levels or 5-HIAA/5-HT. However, within the brain, levels of TNF and 5-HT2A receptor mRNA within various regions increased significantly. This increase in receptor expression is reflected by an increase in the functional response of the 5-HT2A receptor to agonist, DOI. These data suggest that regulation of fatigue and depressive-like moods after episodes of systemic inflammation may be regulated by changes in 5-HT receptor expression, rather than by levels of enzyme activity or cytokine expression in the CNS. PMID:26147001

  10. Multiple conformations of 5-HT2A and 5-HT 2C receptors in rat brain: an autoradiographic study with [125I](±)DOI.

    PubMed

    López-Giménez, Juan F; Vilaró, M Teresa; Palacios, José M; Mengod, Guadalupe

    2013-10-01

    Earlier autoradiographic studies with the 5-HT2 receptor agonist [(125)I](±)DOI in human brain showed unexpected biphasic competition curves for various 5-HT2A antagonists. We have performed similar studies in rat brain regions with selective 5-HT2A (M100907) and 5-HT2C (SB242084) antagonists together with ketanserin and mesulergine. The effect of GTP analogues on antagonist competition was also studied. Increasing concentrations of Gpp(NH)p or GTPγS resulted in a maximal inhibition of [(125)I](±)DOI-specific binding of approximately 50 %. M100907 competed biphasically in all regions. In the presence of 100 μM Gpp(NH)p, M100907 still displaced biphasically the remaining [(125)I](±)DOI binding. Ketanserin showed biphasic curves in some regions and monophasic curves in others. In the latter, Gpp(NH)p evidenced an additional high-affinity site. SB242084 competed biphasically in brainstem nuclei and monophasically in the other regions. In most areas, SB242084 affinities were not notably altered by Gpp(NH)p. Mesulergine competed monophasically in all regions without alteration by Gpp(NH)p. These results conform with the extended ternary complex model of receptor action: receptor exists as an equilibrium of multiple conformations, i.e. ground (R), partly activated (R*) and activated G-protein-coupled (R*G) conformation/s. Thus, [(125)I](±)DOI would label multiple conformations of both 5-HT2A and 5-HT2C receptors in rat brain, and M100907 and ketanserin would recognise these conformations with different affinities.

  11. Changes in the 5-HT2A receptor system in the pre-mammillary hypothalamus of the ewe are related to regulation of LH pulsatile secretion by an endogenous circannual rhythm

    PubMed Central

    Chemineau, Philippe; Daveau, Agnès; Pelletier, Jean; Malpaux, Benoît; Karsch, Fred J; Viguié, Catherine

    2003-01-01

    Background We wanted to determine if changes in the expression of serotonin 2A receptor (5HT2A receptor) gene in the premammillary hypothalamus are associated with changes in reproductive neuroendocrine status. Thus, we compared 2 groups of ovariectomized-estradiol-treated ewes that expressed high vs low LH pulsatility in two different paradigms (2 groups per paradigm): (a) refractoriness (low LH secretion) or not (high LH secretion) to short days in pineal-intact Ile-de-France ewes (RSD) and (b) endogenous circannual rhythm (ECR) in free-running pinealectomized Suffolk ewes in the active or inactive stage of their reproductive rhythm. Results In RSD ewes, density of 5HT2A receptor mRNA (by in situ hybridization) was significantly higher in the high LH group (25.3 ± 1.4 vs 21.4 ± 1.5 grains/neuron, P < 0.05) and 3H-Ketanserin binding (a specific radioligand) of the median part of the premammillary hypothalamus tended to be higher in the high group (29.1 ± 4.0 vs 24.6 ± 4.2 fmol/mg tissu-equivalent; P < 0.10). In ECR ewes, density of 5HT2A receptor mRNA and 3H-Ketanserin binding were both significantly higher in the high LH group (20.8 ± 1.6 vs 17.0 ± 1.5 grains/neuron, P < 0.01, and 19.7 ± 5.0 vs 7.4 ± 3.4 fmol/mg tissu-equivalent; P < 0.05, respectively). Conclusions We conclude that these higher 5HT2A receptor gene expression and binding activity of 5HT2A receptor in the premammillary hypothalamus are associated with stimulation of LH pulsatility expressed before the development of refractoriness to short days and prior to the decline of reproductive neuroendocrine activity during expression of the endogenous circannual rhythm. PMID:12553884

  12. Differential effects of neonatal handling on anxiety, corticosterone response to stress, and hippocampal glucocorticoid and serotonin (5-HT)2A receptors in Lewis rats.

    PubMed

    Durand, M; Sarrieau, A; Aguerre, S; Mormède, P; Chaouloff, F

    1998-05-01

    Neonatal handling (during the first 3 weeks of age) has been reported by others to diminish the hypothalamo-pituitary-adrenal (HPA) responsivity to stress in adult Long Evans rats, an effect involving a serotonin (5-HT)2A receptor-mediated increase in glucocorticoid receptor (GR) gene expression in the frontal cortex and the hippocampus. In addition, handled animals may also display enduring reductions in anxiety-related behaviours, including in the elevated plus-maze. We have thus analysed the aforementioned neuroendocrine and behavioural consequences of neonatal stress in male and female adult Lewis rats, a strain characterised by its high anxiety and its hyporesponsive HPA axis. Plasma corticosterone, but not behavioural, responses to an elevated plus-maze test were decreased in handled rats. Besides, hippocampal mineralocorticoid receptor (MR) and GR binding capacities were not different between handled and non-handled Lewis rats, an observation which could be extended to our adult Long Evans rats. Lastly, neither hippocampal nor cortical 5-HT2A receptor binding capacities in adult Lewis rats were affected by prior handling. In keeping with the failure to detect early handling-induced increases in hippocampal GR binding in 3-week old Lewis and Long Evans rats, the present study reinforces past findings indicating that environmental and genetic factors are crucial variables in the neonatal handling paradigm.

  13. Role for serotonin2A (5-HT2A) and 2C (5-HT2C) receptors in experimental absence seizures.

    PubMed

    Venzi, Marcello; David, François; Bellet, Joachim; Cavaccini, Anna; Bombardi, Cristiano; Crunelli, Vincenzo; Di Giovanni, Giuseppe

    2016-09-01

    Absence seizures (ASs) are the hallmark of childhood/juvenile absence epilepsy. Monotherapy with first-line anti-absence drugs only controls ASs in 50% of patients, indicating the need for novel therapeutic targets. Since serotonin family-2 receptors (5-HT2Rs) are known to modulate neuronal activity in the cortico-thalamo-cortical loop, the main network involved in AS generation, we investigated the effect of selective 5-HT2AR and 5-HT2CR ligands on ASs in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well established polygenic rat model of these non-convulsive seizures. GAERS rats were implanted with fronto-parietal EEG electrodes under general anesthesia, and their ASs were later recorded under freely moving conditions before and after intraperitoneal administration of various 5-HT2AR and 5-HT2CR ligands. The 5-HT2A agonist TCB-2 dose-dependently decreased the total time spent in ASs, an effect that was blocked by the selective 5-HT2A antagonist MDL11,939. Both MDL11,939 and another selective 5-HT2A antagonist (M100,907) increased the length of individual seizures when injected alone. The 5-HT2C agonists lorcaserin and CP-809,101 dose-dependently suppressed ASs, an effect blocked by the selective 5-HT2C antagonist SB 242984. In summary, 5-HT2ARs and 5-HT2CRs negatively control the expression of experimental ASs, indicating that selective agonists at these 5-HT2R subtypes might be potential novel anti-absence drugs.

  14. Role for serotonin2A (5-HT2A) and 2C (5-HT2C) receptors in experimental absence seizures.

    PubMed

    Venzi, Marcello; David, François; Bellet, Joachim; Cavaccini, Anna; Bombardi, Cristiano; Crunelli, Vincenzo; Di Giovanni, Giuseppe

    2016-09-01

    Absence seizures (ASs) are the hallmark of childhood/juvenile absence epilepsy. Monotherapy with first-line anti-absence drugs only controls ASs in 50% of patients, indicating the need for novel therapeutic targets. Since serotonin family-2 receptors (5-HT2Rs) are known to modulate neuronal activity in the cortico-thalamo-cortical loop, the main network involved in AS generation, we investigated the effect of selective 5-HT2AR and 5-HT2CR ligands on ASs in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well established polygenic rat model of these non-convulsive seizures. GAERS rats were implanted with fronto-parietal EEG electrodes under general anesthesia, and their ASs were later recorded under freely moving conditions before and after intraperitoneal administration of various 5-HT2AR and 5-HT2CR ligands. The 5-HT2A agonist TCB-2 dose-dependently decreased the total time spent in ASs, an effect that was blocked by the selective 5-HT2A antagonist MDL11,939. Both MDL11,939 and another selective 5-HT2A antagonist (M100,907) increased the length of individual seizures when injected alone. The 5-HT2C agonists lorcaserin and CP-809,101 dose-dependently suppressed ASs, an effect blocked by the selective 5-HT2C antagonist SB 242984. In summary, 5-HT2ARs and 5-HT2CRs negatively control the expression of experimental ASs, indicating that selective agonists at these 5-HT2R subtypes might be potential novel anti-absence drugs. PMID:27085605

  15. The 5-HT(2A) receptor and serotonin transporter in Asperger's disorder: A PET study with [¹¹C]MDL 100907 and [¹¹C]DASB.

    PubMed

    Girgis, Ragy R; Slifstein, Mark; Xu, Xiaoyan; Frankle, W Gordon; Anagnostou, Evdokia; Wasserman, Stacey; Pepa, Lauren; Kolevzon, Alexander; Abi-Dargham, Anissa; Laruelle, Marc; Hollander, Eric

    2011-12-30

    Evidence from biochemical, imaging, and treatment studies suggest abnormalities of the serotonin system in autism spectrum disorders, in particular in frontolimbic areas of the brain. We used the radiotracers [(11)C]MDL 100907 and [(11)C]DASB to characterize the 5-HT(2A) receptor and serotonin transporter in Asperger's Disorder. Seventeen individuals with Asperger's Disorder (age=34.3 ± 11.1 years) and 17 healthy controls (age=33.0 ± 9.6 years) were scanned with [(11)C]MDL 100907. Of the 17 patients, eight (age=29.7 ± 7.0 years) were also scanned with [¹¹C]DASB, as were eight healthy controls (age=28.7 ± 7.0 years). Patients with Asperger's Disorder and healthy control subjects were matched for age, gender, and ethnicity, and all had normal intelligence. Metabolite-corrected arterial plasma inputs were collected and data analyzed by two-tissue compartment modeling. The primary outcome measure was regional binding potential BP(ND). Neither regional [¹¹C]MDL 100907 BP(ND) nor [¹¹C]DASB BP(ND) was statistically different between the Asperger's and healthy subjects. This study failed to find significant alterations in binding parameters of 5-HT(2A) receptors and serotonin transporters in adult subjects with Asperger's disorder.

  16. A double dissociation in the effects of 5-HT2A and 5-HT2C receptors on the acquisition and expression of conditioned defeat in Syrian hamsters

    PubMed Central

    Harvey, Marquinta L.; Swallows, Cody L.; Cooper, Matthew A.

    2012-01-01

    Previous research indicates that serotonin enhances the development of stress-induced changes in behavior, although it is unclear which serotonin receptors mediate this effect. 5-HT2 receptors are potential candidates because activation at these receptors is associated with increased fear and anxiety. In this study we investigated whether pharmacological treatments targeting 5-HT2 receptors would alter the acquisition and expression of conditioned defeat. Conditioned defeat is a social defeat model in Syrian hamsters in which individuals display increased submissive and defensive behavior and a loss of territorial aggression when tested with a novel intruder 24 hours after an acute social defeat. The nonselective 5-HT2 receptor agonist mCPP (0.0, 0.3, 1.0 or 3.0 mg/kg) was injected either prior to social defeat training or prior to conditioned defeat testing. Also, the 5-HT2A receptor antagonist MDL 11,939 (0.0, 0.5 or 2.0 mg/kg) was injected either prior to social defeat training or prior to conditioned defeat testing. Injection of mCPP prior to testing increased the expression of conditioned defeat, but injection of mCPP prior to training did not alter the acquisition of conditioned defeat. Conversely, injection of MDL 11,939 prior to training reduced the acquisition of conditioned defeat, but injection of MDL 11,939 prior to testing did not alter the expression of conditioned defeat. Our data suggest that mCPP activates 5-HT2C receptors during testing to enhance the display of submissive and defensive behavior, whereas MDL 11,939 blocks 5-HT2A receptors during social defeat to disrupt the development of the conditioned defeat response. In sum, these results suggest that serotonin acts at separate 5-HT2 receptors to facilitate the acquisition and expression of defeat-induced changes in social behavior. PMID:22708954

  17. Cardiac baroreflex facilitation evoked by hypothalamus and prefrontal cortex stimulation: role of the nucleus tractus solitarius 5-HT2A receptors.

    PubMed

    Sévoz-Couche, C; Comet, M A; Bernard, J F; Hamon, M; Laguzzi, R

    2006-10-01

    We previously showed that serotonin (5-HT2) receptor activation in the nucleus of the tractus solitarius (NTS) produced hypotension, bradycardia, and facilitation of the baroreflex bradycardia. Activation of the preoptic area (POA) of the hypothalamus, which is involved in shock-evoked passive behaviors, induces similar modifications. In addition, previous studies showed that blockade of the infralimbic (IL) part of the medial prefrontal cortex, which sends projections to POA, produced an inhibitory influence on the baroreflex cardiac response. Thus, to assess the possible implication of NTS 5-HT2 receptors in passive cardiovascular responses, we analyzed in anesthetized rats the effects of NTS inhibition and NTS 5-HT2 receptor blockade on the cardiovascular modifications induced by chemical (0.3 M D,L-homocysteic acid) and electrical (50 Hz, 150-200 microA) stimulation of IL or POA. Intra-NTS microinjections of muscimol, a GABAA receptor agonist, prevented the decreases in blood pressure and heart rate normally evoked by IL or POA activation. In addition, we found that intra-NTS microinjection of R(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine-methanol, a specific 5-HT2A receptor antagonist, did not affect the decreases in cardiovascular baseline parameters induced by IL or POA stimulation but prevented the facilitation of the aortic baroreflex bradycardia normally observed during IL (+65 and +60%) or POA (+70 and +69%) electrical and chemical stimulation, respectively. These results show that NTS 5-HT2A receptors play a key role in the enhancement of the cardiac response of the baroreflex but not in the changes in basal heart rate and blood pressure induced by IL or POA stimulation. PMID:16763082

  18. Effects of imipramine and bupropion on the duration of immobility of ACTH-treated rats in the forced swim test: involvement of the expression of 5-HT2A receptor mRNA.

    PubMed

    Kitamura, Yoshihisa; Fujitani, Yoshika; Kitagawa, Kouhei; Miyazaki, Toshiaki; Sagara, Hidenori; Kawasaki, Hiromu; Shibata, Kazuhiko; Sendo, Toshiaki; Gomita, Yutaka

    2008-02-01

    We examined the effect of chronic administration of imipramine and bupropion, monoamine reuptake inhibitors, on the duration of immobility in the forced swim test and serotonin (5-HT)(2A) receptor function in the form of 5-HT(2A) receptor mRNA levels in rats chronically treated with adrenocorticotropic hormone (ACTH). The immobility-decreasing effect of bupropion without imipramine did not influence the chronic ACTH treatment. The effect on the expression of 5-HT(2A) receptor mRNA of chronic ACTH treatment was decreased by bupropion, but not imipramine. These results suggest that bupropion has the effect of reducing immobility time in the forced swim test in the tricyclic antidepressant-resistant depressive model induced by chronic ACTH treatment in rats, and that decreased 5-HT(2A) receptor mRNA levels may be involved in this phenomenon.

  19. Serotonin contracts the rat mesenteric artery by inhibiting 4-aminopyridine-sensitive Kv channels via the 5-HT2A receptor and Src tyrosine kinase.

    PubMed

    Sung, Dong Jun; Noh, Hyun Ju; Kim, Jae Gon; Park, Sang Woong; Kim, Bokyung; Cho, Hana; Bae, Young Min

    2013-01-01

    Serotonin (5-hydroxytryptamine (5-HT)) is a neurotransmitter that regulates a variety of functions in the nervous, gastrointestinal and cardiovascular systems. Despite such importance, 5-HT signaling pathways are not entirely clear. We demonstrated previously that 4-aminopyridine (4-AP)-sensitive voltage-gated K(+) (Kv) channels determine the resting membrane potential of arterial smooth muscle cells and that the Kv channels are inhibited by 5-HT, which depolarizes the membranes. Therefore, we hypothesized that 5-HT contracts arteries by inhibiting Kv channels. Here we studied 5-HT signaling and the detailed role of Kv currents in rat mesenteric arteries using patch-clamp and isometric tension measurements. Our data showed that inhibiting 4-AP-sensitive Kv channels contracted arterial rings, whereas inhibiting Ca(2+)-activated K(+), inward rectifier K(+) and ATP-sensitive K(+) channels had little effect on arterial contraction, indicating a central role of Kv channels in the regulation of resting arterial tone. 5-HT-induced arterial contraction decreased significantly in the presence of high KCl or the voltage-gated Ca(2+) channel (VGCC) inhibitor nifedipine, indicating that membrane depolarization and the consequent activation of VGCCs mediate the 5-HT-induced vasoconstriction. The effects of 5-HT on Kv currents and arterial contraction were markedly prevented by the 5-HT2A receptor antagonists ketanserin and spiperone. Consistently, α-methyl 5-HT, a 5-HT2 receptor agonist, mimicked the 5-HT action on Kv channels. Pretreatment with a Src tyrosine kinase inhibitor, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine, prevented both the 5-HT-mediated vasoconstriction and Kv current inhibition. Our data suggest that 4-AP-sensitive Kv channels are the primary regulator of the resting tone in rat mesenteric arteries. 5-HT constricts the arteries by inhibiting Kv channels via the 5-HT2A receptor and Src tyrosine kinase pathway. PMID:24336234

  20. Serotonin (5-HT) and 5-HT2A receptor agonists suppress lipolysis in primary rat adipose cells.

    PubMed

    Hansson, Björn; Medina, Anya; Fryklund, Claes; Fex, Malin; Stenkula, Karin G

    2016-05-27

    Serotonin (5-HT) is a biogenic monoamine that functions both as a neurotransmitter and a circulating hormone. Recently, the metabolic effects of 5-HT have gained interest and peripheral 5-HT has been proposed to influence lipid metabolism in various ways. Here, we investigated the metabolic effects of 5-HT in isolated, primary rat adipose cells. Incubation with 5-HT suppressed β-adrenergically stimulated glycerol release and decreased phosphorylation of protein kinase A (PKA)-dependent substrates, hormone sensitive lipase (Ser563) and perilipin (Ser522). The inhibitory effect of 5-HT on lipolysis enhanced the anti-lipolytic effect of insulin, but sustained in the presence of phosphodiesterase inhibitors, OPC3911 and isobuthylmethylxanthine (IBMX). The relative expression of 5-HT1A, -2B and -4 receptor class family were significantly higher in adipose tissue compared to adipose cells, whereas 5-HT1D, -2A and -7 were highly expressed in isolated adipose cells. Similar to 5-HT, 5-HT2 receptor agonists reduced lipolysis while 5-HT1 receptor agonists rather decreased non-stimulated and insulin-stimulated glucose uptake. Together, these data provide evidence of a direct effect of 5-HT on adipose cells, where 5-HT suppresses lipolysis and glucose uptake, which could contribute to altered systemic lipid- and glucose metabolism. PMID:27109474

  1. 5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats

    PubMed Central

    Martin-Gronert, Malgorzata S.; Stocker, Claire J.; Wargent, Edward T.; Cripps, Roselle L.; Garfield, Alastair S.; Jovanovic, Zorica; D'Agostino, Giuseppe; Yeo, Giles S. H.; Cawthorne, Michael A.; Arch, Jonathan R. S.; Heisler, Lora K.; Ozanne, Susan E.

    2016-01-01

    ABSTRACT Although obesity is a global epidemic, the physiological mechanisms involved are not well understood. Recent advances reveal that susceptibility to obesity can be programmed by maternal and neonatal nutrition. Specifically, a maternal low-protein diet during pregnancy causes decreased intrauterine growth, rapid postnatal catch-up growth and an increased risk for diet-induced obesity. Given that the synthesis of the neurotransmitter 5-hydroxytryptamine (5-HT) is nutritionally regulated and 5-HT is a trophic factor, we hypothesised that maternal diet influences fetal 5-HT exposure, which then influences development of the central appetite network and the subsequent efficacy of 5-HT to control energy balance in later life. Consistent with our hypothesis, pregnant rats fed a low-protein diet exhibited elevated serum levels of 5-HT, which was also evident in the placenta and fetal brains at embryonic day 16.5. This increase was associated with reduced levels of 5-HT2CR, the primary 5-HT receptor influencing appetite, in the fetal, neonatal and adult hypothalamus. As expected, a reduction of 5-HT2CR was associated with impaired sensitivity to 5-HT-mediated appetite suppression in adulthood. 5-HT primarily achieves effects on appetite by 5-HT2CR stimulation of pro-opiomelanocortin (POMC) peptides within the arcuate nucleus of the hypothalamus (ARC). We show that 5-HT2ARs are also anatomically positioned to influence the activity of ARC POMC neurons and that mRNA encoding 5-HT2AR is increased in the hypothalamus of in utero growth-restricted offspring that underwent rapid postnatal catch-up growth. Furthermore, these animals at 3 months of age are more sensitive to appetite suppression induced by 5-HT2AR agonists. These findings not only reveal a 5-HT-mediated mechanism underlying the programming of susceptibility to obesity, but also provide a promising means to correct it, by treatment with a 5-HT2AR agonist. PMID:26769798

  2. Potential Modes of Interaction of 9-Aminomethyl-9,10-dihydroanthracene (AMDA) Derivatives with the 5-HT2A Receptor: A Ligand Structure-Affinity Relationship, Receptor Mutagenesis and Receptor Modeling Investigation⊕

    PubMed Central

    Runyon, Scott P.; Mosier, Philip D.; Roth, Bryan L.; Glennon, Richard A.; Westkaemper, Richard B.

    2011-01-01

    The effects of 3-position substitution of 9-aminomethyl-9,10-dihydroanthracene (AMDA) on 5-HT2A receptor affinity were determined and compared to a parallel series of DOB-like 1-(2,5-dimethoxyphenyl)-2-aminopropanes substituted at the 4-position. The results were interpreted within the context of 5-HT2A receptor models that suggest that members of the DOB-like series can bind to the receptor in two distinct modes that correlate with the compounds’ functional activity. Automated ligand docking and molecular dynamics suggest that all of the AMDA derivatives, the parent of which is a 5-HT2A antagonist, bind in a fashion analogous to that for the sterically demanding antagonist DOB-like compounds. The failure of the F3406.52L mutation to adversely affect the affinity of AMDA and the 3-bromo derivative is consistent with the proposed modes of orientation. Evaluation of ligand-receptor complex models suggest that a valine/threonine exchange between the 5-HT2A and D2 receptors may be the origin of selectivity for AMDA and two substituted derivatives. PMID:18847250

  3. Synthesis and structure-affinity relationships of novel small molecule natural product derivatives capable of discriminating between serotonin 5-HT1A, 5-HT2A, 5-HT2C receptor subtypes

    PubMed Central

    Cummings, David F.; Canseco, Diana C.; Sheth, Pratikkumar; Johnson, James E.; Schetz, John A.

    2010-01-01

    Efforts to develop ligands that distinguish between clinically relevant 5-HT2A and 5-HT2C serotonin receptor subtypes have been challenging, because their sequences have high homology. Previous studies reported that a novel aplysinopsin belonging to a chemical class of natural products isolated from a marine sponge was selective for the 5-HT2C over the 5-HT2A receptor subtype. Our goal was to explore the 5-HT2A/2C receptor structure-affinity relationships of derivatives based on the aplysinopsin natural product pharmacophore. Twenty aplysinopsin derivatives were synthesized, purified and tested for their affinities for cloned human serotonin 5-HT1A, 5-HT2A and 5-HT2C receptor subtypes. Four compounds in this series had >30-fold selectivity for 5-HT2A or 5-HT2C receptors. The compound (E)-5-((5,6-dichloro-1H-indol-3-yl)methylene)-2-imino-1,3-dimethylimidazolidin-4-one (UNT-TWU-22, 16) had approximately 2100-fold selectivity for the serotonin 5-HT2C receptor subtype: an affinity for 5-HT2C equal to 46 nM and no detectable affinity for the 5-HT1A or 5-HT2A receptor subtypes. The two most important factors controlling 5-HT2A or 5-HT2C receptor subtype selectivity were the combined R1, R3-alkylation of the imidazolidinone ring and the type and number of halogens on the indole ring of the aplysinopsin pharmacophore. PMID:20570529

  4. Metabotropic glutamate mGlu2 receptor is necessary for the pharmacological and behavioral effects induced by hallucinogenic 5-HT2A receptor agonists.

    PubMed

    Moreno, José L; Holloway, Terrell; Albizu, Laura; Sealfon, Stuart C; González-Maeso, Javier

    2011-04-15

    Hallucinogenic drugs, including mescaline, psilocybin and lysergic acid diethylamide (LSD), act at serotonin 5-HT2A receptors (5-HT2ARs). Metabotropic glutamate receptor 2/3 (mGluR2/3) ligands show efficacy in modulating the responses induced by activation of 5-HT2ARs. The formation of a 5-HT2AR-mGluR2 complex suggests a functional interaction that affects the hallucinogen-regulated cellular signaling pathways. Here, we tested the cellular and behavioral effects of hallucinogenic 5-HT2AR agonists in mGluR2 knockout (mGluR2-KO) mice. Mice were intraperitoneally injected with the hallucinogens DOI (2 mg/kg) and LSD (0.24 mg/kg), or vehicle. Head-twitch behavioral response, expression of c-fos, which is induced by all 5-HT2AR agonists, and expression of egr-2, which is hallucinogen-specific, were determined in wild type and mGluR2-KO mice. [(3)H]Ketanserin binding displacement curves by DOI were performed in mouse frontal cortex membrane preparations. Head twitch behavior was abolished in mGluR2-KO mice. The high-affinity binding site of DOI was undetected in mGluR2-KO mice. The hallucinogen DOI induced c-fos in both wild type and mGluR2-KO mice. However, the induction of egr-2 by DOI was eliminated in mGlu2-KO mice. These findings suggest that the 5-HT2AR-mGluR2 complex is necessary for the neuropsychological responses induced by hallucinogens.

  5. Potentiation of 5-methoxy-N,N-dimethyltryptamine-induced hyperthermia by harmaline and the involvement of activation of 5-HT1A and 5-HT2A receptors.

    PubMed

    Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

    2015-02-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are serotonin (5-HT) analogs often abused together, which alters thermoregulation that may indicate the severity of serotonin toxicity. Our recent studies have revealed that co-administration of monoamine oxidase inhibitor harmaline leads to greater and prolonged exposure to 5-HT agonist 5-MeO-DMT that might be influenced by cytochrome P450 2D6 (CYP2D6) status. This study was to define the effects of harmaline and 5-MeO-DMT on thermoregulation in wild-type and CYP2D6-humanized (Tg-CYP2D6) mice, as well as the involvement of 5-HT receptors. Animal core body temperatures were monitored noninvasively in the home cages after implantation of telemetry transmitters and administration of drugs. Harmaline (5 and 15 mg/kg, i.p.) alone was shown to induce hypothermia that was significantly affected by CYP2D6 status. In contrast, higher doses of 5-MeO-DMT (10 and 20 mg/kg) alone caused hyperthermia. Co-administration of harmaline (2, 5 or 15 mg/kg) remarkably potentiated the hyperthermia elicited by 5-MeO-DMT (2 or 10 mg/kg), which might be influenced by CYP2D6 status at certain dose combination. Interestingly, harmaline-induced hypothermia was only attenuated by 5-HT1A receptor antagonist WAY-100635, whereas 5-MeO-DMT- and harmaline-5-MeO-DMT-induced hyperthermia could be suppressed by either WAY-100635 or 5-HT2A receptor antagonists (MDL-100907 and ketanserin). Moreover, stress-induced hyperthermia under home cage conditions was not affected by WAY-100635 but surprisingly attenuated by MDL-100907 and ketanserin. Our results indicate that co-administration of monoamine oxidase inhibitor largely potentiates 5-MeO-DMT-induced hyperthermia that involves the activation of both 5-HT1A and 5-HT2A receptors. These findings shall provide insights into development of anxiolytic drugs and new strategies to relieve the lethal hyperthermia in serotonin toxicity.

  6. Serotonin 5-HT2A receptor binding in platelets from healthy subjects as studied by [3H]-lysergic acid diethylamide ([3H]-LSD): intra- and interindividual variability.

    PubMed

    Spigset, O; Mjörndal, T

    1997-04-01

    In studies on platelet 5-HT2A receptor binding in patients with neuropsychiatric disorders, there has been a marked variability and a considerable overlap of values between patients and controls. The causes of the large variability in 5-HT2A receptor parameters is still unsettled. In the present study, we have quantified the intra- and interindividual variability of platelet 5-HT2A receptor binding in 112 healthy subjects and explored factors that may influence 5-HT2A receptor binding, using [3H]-lysergic acid diethylamide as radioligand. Age, gender, blood pressure, and metabolic capacity of the liver enzymes CYP2D6 and CYP2C19 did not influence Bmax and Kd values. Body weight and body mass index (BMI) showed a negative correlation with Kd (p = .04 and .03, respectively), but not with Bmax. Bmax was significantly lower in the light half of the year than in the dark half of the year (p = .001), and Kd was significantly lower in the fall than in the summer and winter (p < .001). In females, there was a significant increase in Bmax from week 1 to week 2 of the menstrual cycle (p = .03). Females taking contraceptive pills had significantly higher Kd than drug-free females in weeks 1 and 4 of the menstrual cycle (p = .04). This study shows that a number of factors should be taken into account when using platelet 5-HT2A receptor binding in studies of neuropsychiatric disorders.

  7. Cognitive Impairment Induced by Delta9-tetrahydrocannabinol Occurs through Heteromers between Cannabinoid CB1 and Serotonin 5-HT2A Receptors

    PubMed Central

    Lanfumey, Laurence; Cordomí, Arnau; Pastor, Antoni; de La Torre, Rafael; Gasperini, Paola; Navarro, Gemma; Howell, Lesley A.; Pardo, Leonardo; Lluís, Carmen; Canela, Enric I.; McCormick, Peter J.; Maldonado, Rafael; Robledo, Patricia

    2015-01-01

    Activation of cannabinoid CB1 receptors (CB1R) by delta9-tetrahydrocannabinol (THC) produces a variety of negative effects with major consequences in cannabis users that constitute important drawbacks for the use of cannabinoids as therapeutic agents. For this reason, there is a tremendous medical interest in harnessing the beneficial effects of THC. Behavioral studies carried out in mice lacking 5-HT2A receptors (5-HT2AR) revealed a remarkable 5-HT2AR-dependent dissociation in the beneficial antinociceptive effects of THC and its detrimental amnesic properties. We found that specific effects of THC such as memory deficits, anxiolytic-like effects, and social interaction are under the control of 5-HT2AR, but its acute hypolocomotor, hypothermic, anxiogenic, and antinociceptive effects are not. In biochemical studies, we show that CB1R and 5-HT2AR form heteromers that are expressed and functionally active in specific brain regions involved in memory impairment. Remarkably, our functional data shows that costimulation of both receptors by agonists reduces cell signaling, antagonist binding to one receptor blocks signaling of the interacting receptor, and heteromer formation leads to a switch in G-protein coupling for 5-HT2AR from Gq to Gi proteins. Synthetic peptides with the sequence of transmembrane helices 5 and 6 of CB1R, fused to a cell-penetrating peptide, were able to disrupt receptor heteromerization in vivo, leading to a selective abrogation of memory impairments caused by exposure to THC. These data reveal a novel molecular mechanism for the functional interaction between CB1R and 5-HT2AR mediating cognitive impairment. CB1R-5-HT2AR heteromers are thus good targets to dissociate the cognitive deficits induced by THC from its beneficial antinociceptive properties. PMID:26158621

  8. Antidepressant-like activity of Tagetes lucida Cav. is mediated by 5-HT(1A) and 5-HT(2A) receptors.

    PubMed

    Bonilla-Jaime, H; Guadarrama-Cruz, G; Alarcon-Aguilar, F J; Limón-Morales, O; Vazquez-Palacios, G

    2015-10-01

    It has been demonstrated that the aqueous extract of Tagetes lucida Cav. shows an antidepressant-like effect on the forced swimming test (FST) in rats. The aim of this study was to analyze the participation of the serotoninergic system in the antidepressant-like effect of the aqueous extract of T. lucida. Different doses of the extract of T. lucida were administered at 72, 48, 24, 18 and 1 h before FST. The animals were pretreated with a 5-HT1A receptor antagonist (WAY-100635, 0.5 mg/kg), a 5-HT2A receptor antagonist (ketanserin, 5 mg/kg), a β-noradrenergic receptor antagonist (propranolol, 200 mg/kg), and with a α2-noradrenergic receptor antagonist (yohimbine, 1 mg/kg) alone or combined with the extract and pretreated with a serotonin synthesis inhibitor (PCPA) before treatment with 8-OH-DPAT + the extract of T. lucida. In addition, suboptimal doses of the 5-HT1A agonist (8-OH-DPAT) + non-effective dose of extract was analyzed in the FST. To determine the presence of flavonoids, the aqueous extract of T. lucida (20 µl, 4 mg/ml) was injected in HPLC; however, a quercetin concentration of 7.72 mg/g of extract weight was detected. A suboptimal dose of 8-OH-DPAT + extract of T. lucida decreased immobility and increased swimming and climbing. An antidepressant-like effect with the aqueous extract of T. lucida at doses of 100 and 200 mg/kg was observed on the FST with decreased immobility behavior and increased swimming; however, this effect was blocked by WAY-100635, ketanserin and PCPA but not by yohimbine and propranolol, suggesting that the extract of T. lucida could be modulating the release/reuptake of serotonin.

  9. Examination of the hippocampal contribution to serotonin 5-HT2A receptor-mediated facilitation of object memory in C57BL/6J mice.

    PubMed

    Zhang, Gongliang; Cinalli, David; Cohen, Sarah J; Knapp, Kristina D; Rios, Lisa M; Martínez-Hernández, José; Luján, Rafael; Stackman, Robert W

    2016-10-01

    The rodent hippocampus supports non-spatial object memory. Serotonin 5-HT2A receptors (5-HT2AR) are widely expressed throughout the hippocampus. We previously demonstrated that the activation of 5-HT2ARs enhanced the strength of object memory assessed 24 h after a limited (i.e., weak memory) training procedure. Here, we examined the subcellular distribution of 5-HT2ARs in the hippocampal CA1 region and underlying mechanisms of 5-HT2AR-mediated object memory consolidation. Analyses with immuno-electron microscopy revealed the presence of 5-HT2ARs on the dendritic spines and shafts of hippocampal CA1 neurons, and presynaptic terminals in the CA1 region. In an object recognition memory procedure that places higher demand on the hippocampus, only post-training systemic or intrahippocampal administration of the 5-HT2AR agonist TCB-2 enhanced object memory. Object memory enhancement by TCB-2 was blocked by the 5-HT2AR antagonist, MDL 11,937. The memory-enhancing dose of systemic TCB-2 increased extracellular glutamate levels in hippocampal dialysate samples, and increased the mean in vivo firing rate of hippocampal CA1 neurons. In summary, these data indicate a pre- and post-synaptic distribution of 5-HT2ARs, and activation of 5-HT2ARs selectively enhanced the consolidation of object memory, without affecting encoding or retrieval. The 5-HT2AR-mediated facilitation of hippocampal memory may be associated with an increase in hippocampal neuronal firing and glutamate efflux during a post-training time window in which recently encoded memories undergo consolidation.

  10. Molecular Pharmacology and Ligand Docking Studies Reveal a Single Amino Acid Difference between Mouse and Human Serotonin 5-HT2A Receptors That Impacts Behavioral Translation of Novel 4-Phenyl-2-dimethylaminotetralin Ligands

    PubMed Central

    Cordova-Sintjago, Tania; Liu, Yue; Kim, Myong S.; Morgan, Drake; Booth, Raymond G.

    2013-01-01

    During translational studies to develop 4-phenyl-2-dimethylaminotetralin (PAT) compounds for neuropsychiatric disorders, the (2R,4S)-trans-(+)- and (2S,4R)-trans-(−)-enantiomers of the analog 6-hydroxy-7-chloro-PAT (6-OH-7-Cl-PAT) demonstrated unusual pharmacology at serotonin (5-HT) 5-HT2 G protein–coupled receptors (GPCRs). The enantiomers had similar affinities (Ki) at human (h) 5-HT2A receptors (∼70 nM). In an in vivo mouse model of 5-HT2A receptor activation [(±)-(2,5)-dimethoxy-4-iodoamphetamine (DOI)–elicited head twitch], however, (−)-6-OH-7-Cl-PAT was about 5-fold more potent than the (+)-enantiomer at attenuating the DOI-elicited response. It was discovered that (+)-6-OH-7-Cl-PAT (only) had ∼40-fold-lower affinity at mouse (m) compared with h5-HT2A receptors. Molecular modeling and computational ligand docking studies indicated that the 6-OH moiety of (+)- but not (−)-6-OH-7-Cl-PAT could form a hydrogen bond with serine residue 5.46 of the h5-HT2A receptor. The m5-HT2A as well as m5-HT2B, h5-HT2B, m5-HT2C, and h5-HT2C receptors have alanine at position 5.46, obviating this interaction; (+)-6-OH-7-Cl-PAT also showed ∼50-fold lower affinity than (−)-6-OH-7-Cl-PAT at m5-HT2C and h5-HT2C receptors. Mutagenesis studies confirmed that 5-HT2A S5.46 is critical for (+)- but not (−)-6-OH-7-Cl-PAT binding, as well as function. The (+)-6-OH-7-Cl-PAT enantiomer showed partial agonist effects at h5-HT2A wild-type (WT) and m5-HT2A A5.46S point-mutated receptors but did not activate m5-HT2A WT and h5-HT2A S5.46A point-mutated receptors, or h5-HT2B, h5-HT2C, and m5-HT2C receptors; (−)-6-OH-7-Cl-PAT did not activate any of the 5-HT2 receptors. Experiments also included the (2R,4S)-trans-(+)- and (2S,4R)-trans-(−)-enantiomers of 6-methoxy-7-chloro-PAT to validate hydrogen bonding interactions proposed for the corresponding 6-OH analogs. Results indicate that PAT ligand three-dimensional structure impacts target receptor binding and translational

  11. Blonanserin Ameliorates Phencyclidine-Induced Visual-Recognition Memory Deficits: the Complex Mechanism of Blonanserin Action Involving D3-5-HT2A and D1-NMDA Receptors in the mPFC

    PubMed Central

    Hida, Hirotake; Mouri, Akihiro; Mori, Kentaro; Matsumoto, Yurie; Seki, Takeshi; Taniguchi, Masayuki; Yamada, Kiyofumi; Iwamoto, Kunihiro; Ozaki, Norio; Nabeshima, Toshitaka; Noda, Yukihiro

    2015-01-01

    Blonanserin differs from currently used serotonin 5-HT2A/dopamine-D2 receptor antagonists in that it exhibits higher affinity for dopamine-D2/3 receptors than for serotonin 5-HT2A receptors. We investigated the involvement of dopamine-D3 receptors in the effects of blonanserin on cognitive impairment in an animal model of schizophrenia. We also sought to elucidate the molecular mechanism underlying this involvement. Blonanserin, as well as olanzapine, significantly ameliorated phencyclidine (PCP)-induced impairment of visual-recognition memory, as demonstrated by the novel-object recognition test (NORT) and increased extracellular dopamine levels in the medial prefrontal cortex (mPFC). With blonanserin, both of these effects were antagonized by DOI (a serotonin 5-HT2A receptor agonist) and 7-OH-DPAT (a dopamine-D3 receptor agonist), whereas the effects of olanzapine were antagonized by DOI but not by 7-OH-DPAT. The ameliorating effect was also antagonized by SCH23390 (a dopamine-D1 receptor antagonist) and H-89 (a protein kinase A (PKA) inhibitor). Blonanserin significantly remediated the decrease in phosphorylation levels of PKA at Thr197 and of NR1 (an essential subunit of N-methyl-D-aspartate (NMDA) receptors) at Ser897 by PKA in the mPFC after a NORT training session in the PCP-administered mice. There were no differences in the levels of NR1 phosphorylated at Ser896 by PKC in any group. These results suggest that the ameliorating effect of blonanserin on PCP-induced cognitive impairment is associated with indirect functional stimulation of the dopamine-D1-PKA-NMDA receptor pathway following augmentation of dopaminergic neurotransmission due to inhibition of both dopamine-D3 and serotonin 5-HT2A receptors in the mPFC. PMID:25120077

  12. Combined serotonin (5-HT)1A agonism, 5-HT(2A) and dopamine D₂ receptor antagonism reproduces atypical antipsychotic drug effects on phencyclidine-impaired novel object recognition in rats.

    PubMed

    Oyamada, Yoshihiro; Horiguchi, Masakuni; Rajagopal, Lakshmi; Miyauchi, Masanori; Meltzer, Herbert Y

    2015-05-15

    Subchronic administration of an N-methyl-D-aspartate receptor (NMDAR) antagonist, e.g. phencyclidine (PCP), produces prolonged impairment of novel object recognition (NOR), suggesting they constitute a hypoglutamate-based model of cognitive impairment in schizophrenia (CIS). Acute administration of atypical, e.g. lurasidone, but not typical antipsychotic drugs (APDs), e.g. haloperidol, are able to restore NOR following PCP (acute reversal model). Furthermore, atypical APDs, when co-administered with PCP, have been shown to prevent development of NOR deficits (prevention model). Most atypical, but not typical APDs, are more potent 5-HT(2A) receptor inverse agonists than dopamine (DA) D2 antagonists, and have been shown to enhance cortical and hippocampal efflux and to be direct or indirect 5-HT(1A) agonists in vivo. To further clarify the importance of these actions to the restoration of NOR by atypical APDs, sub-effective or non-effective doses of combinations of the 5-HT(1A) partial agonist (tandospirone), the 5-HT(2A) inverse agonist (pimavanserin), or the D2 antagonist (haloperidol), as well as the combination of all three agents, were studied in the acute reversal and prevention PCP models of CIS. Only the combination of all three agents restored NOR and prevented the development of PCP-induced deficit. Thus, this triple combination of 5-HT(1A) agonism, 5-HT(2A) antagonism/inverse agonism, and D2 antagonism is able to mimic the ability of atypical APDs to prevent or ameliorate the PCP-induced NOR deficit, possibly by stimulating signaling cascades from D1 and 5-HT(1A) receptor stimulation, modulated by D2 and 5-HT(2A) receptor antagonism. PMID:25448429

  13. The antidepressant-like activity of 6-methoxy-2-[4-(2-methoxyphenyl)piperazin-1-yl]-9H-xanthen-9-one involves serotonergic 5-HT(1A) and 5-HT(2A/C) receptors activation.

    PubMed

    Pytka, Karolina; Walczak, Maria; Kij, Agnieszka; Rapacz, Anna; Siwek, Agata; Kazek, Grzegorz; Olczyk, Adrian; Gałuszka, Adam; Waszkielewicz, Anna; Marona, Henryk; Sapa, Jacek; Filipek, Barbara

    2015-10-01

    Xanthone derivatives have been shown to posses many biological properties. Some of them act within the central nervous system and show neuroprotective or antidepressant-like properties. Taking this into account we investigated antidepressant-like activity in mice and the possible mechanism of action of 6-methoxy-2-[4-(2-methoxyphenyl)piperazin-1-yl]-9H-xanthen-9-one (HBK-11) - a new xanthone derivative. We demonstrated that HBK-11 produced antidepressant-like effects in the forced swim test and tail suspension test, comparable to that of venlafaxine. The combined treatment with sub-effective doses of HBK-11 and fluoxetine (but not reboxetine or bupropion) significantly reduced the immobility in the forced swim test. Moreover, the antidepressant-like activity of HBK-11 in the aforementioned test was blocked by p-chlorophenylalanine, and significantly reduced by serotonergic 5HT1A receptor antagonist - WAY-1006335 and 5HT2A/C receptor antagonist - ritanserin. As none of the above treatments influenced the spontaneous locomotor activity, it can be concluded that HBK-11 mediates its activity through a serotonergic system, and its antidepressant-like effect involves 5HT1A and 5HT2A/C receptor activation. Furthermore, at antidepressant-like doses HBK-11 did not cause the mice to display locomotor deficits in rotarod or chimney tests. Considering the pharmacokinetic profile, HBK-11 demonstrated rapid absorption after i.p. administration, high clearance value, short terminal half-life, very high volume of distribution and incomplete bioavailability. The compound studied had good penetration into the brain tissue of mice. Since studied xanthone derivative seems to present interesting, untypical mechanism of antidepressant-like action i.e. 5HT2A/C receptor activation, it may have a potential in the treatment of depressive disorders, and surely requires further studies. PMID:26210317

  14. Inhibition of SNL-induced upregulation of CGRP and NPY in the spinal cord and dorsal root ganglia by the 5-HT(2A) receptor antagonist ketanserin in rats.

    PubMed

    Wang, Dongmei; Chen, Tingjun; Gao, Yun; Quirion, Rémi; Hong, Yanguo

    2012-05-01

    Our previous study has demonstrated that topical and systemic administration of the 5-HT(2A) receptor antagonist ketanserin attenuates neuropathic pain. To explore the mechanisms involved, we examined whether ketanserin reversed the plasticity changes associated with calcitonin gene-related peptides (CGRP) and neuropeptide Y (NPY) which may reflect distinct mechanisms: involvement and compensatory protection. Behavioral responses to thermal and tactile stimuli after spinal nerve ligation (SNL) at L5 demonstrated neuropathic pain and its attenuation in the vehicle- and ketanserin-treated groups, respectively. SNL surgery induced an increase in CGRP and NPY immunoreactivity (IR) in laminae I-II of the spinal cord. L5 SNL produced an expression of NPY-IR in large, medium and small diameter neurons in dorsal root ganglion (DRG) only at L5, but not adjacent L4 and L6. Daily injection of ketanserin (0.3 mg/kg, s.c.) for two weeks suppressed the increase in CGRP-IR and NPY-IR in the spinal cord or DRG. The present study demonstrated that: (1) the expression of CGRP was enhanced in the spinal dorsal horn and NPY was expressed in the DRG containing injured neurons, but not in the adjacent DRG containing intact neurons, following L5 SNL; (2) the maladaptive changes in CGRP and NPY expression in the spinal cord and DRG mediated the bioactivity of 5-HT/5-HT(2A) receptors in neuropathic pain and (3) the blockade of 5-HT(2A) receptors by ketanserin reversed the evoked upregulation of both CGRP and NPY in the spinal cord and DRG contributing to the inhibition of neuropathic pain.

  15. The highly selective 5-hydroxytryptamine (5-HT)2A receptor antagonist, EMD 281014, significantly increases swimming and decreases immobility in male congenital learned helpless rats in the forced swim test.

    PubMed

    Patel, Jignesh G; Bartoszyk, Gerd D; Edwards, Emmeline; Ashby, Charles R

    2004-04-01

    We examined the effect of the highly selective 5-hydroxytryptamine (5-HT)(2A) receptor antagonist 7-[4-[2-(4-fluoro-phenyl)-ethyl]-piperazine-1-carbonyl]-1H-indole-3-carbonitrile HCl (EMD 281014) in congenital learned helpless male rats in the forced swim test. The administration of EMD-281014 (0.3-30 mg/kg i.p.) to congenital learned helpless rats dose-dependently and significantly (at 10 and 30 mg/kg) decreased immobility and increased swimming compared to vehicle-treated animals. Thus, EMD 281014 produces effects in the forced swim test resembling those of antidepressants.

  16. The role of the 5-HT2A and 5-HT2C receptors in the stimulus effects of hallucinogenic drugs. III: The mechanistic basis for supersensitivity to the LSD stimulus following serotonin depletion.

    PubMed

    Fiorella, D; Helsley, S; Lorrain, D S; Rabin, R A; Winter, J C

    1995-10-01

    The present study was designed to determine the effects of p-chlorophenylalanine (PCPA) and p-chloroamphetamine (PCA) administration on (1) the levels of serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in rat brain, (2) the sensitivity of LSD-trained rats to the stimulus effects of LSD, and (3) the maximal levels of 5-HT2A and 5-HT2C receptor mediated phosphoinositide (PI) hydrolysis in rat brain. PCA and PCPA both produced a significant depletion of whole brain 5-HT and 5-HIAA concentrations. The depletion of serotonin with PCPA, but not PCA, resulted in supersensitivity of LSD-trained subjects to the stimulus effects of LSD. Neither PCPA nor PCA treatment altered the maximal level of 5-HT2A receptor-mediated PI hydrolysis. However, PCPA, but not PCA, treatment resulted in a significant upregulation (46%, P < 0.05) of the maximal level of 5-HT2C receptor mediated PI hydrolysis. These data suggest that upregulation of the 5-HT2C receptor mediates the supersensitivity to LSD discriminative stimulus which follows the depletion of central nervous system serotonin by PCPA.

  17. Binding of [(3)H]lysergic acid diethylamide to serotonin 5-HT(2A) receptors and of [(3)H]paroxetine to serotonin uptake sites in platelets from healthy children, adolescents and adults.

    PubMed

    Sigurdh, J; Spigset, O; Allard, P; Mjörndal, T; Hägglöf, B

    1999-11-01

    Possible age effects on binding of [(3)H]lysergic acid diethylamide ([(3)H]LSD) to serotonin 5-HT(2A) receptors and of [(3)H]paroxetine to serotonin uptake sites were studied in platelets from healthy children (11-12 years of age), adolescents (16-17 years of age) and adults. Significant overall age effects were found both for the number of binding sites (B(max)) for [(3)H]LSD binding (p < 0.001), the affinity constant (K(d)) for [(3)H]LSD binding (p < 0.001), B(max) for [(3)H]paroxetine binding (p < 0.001) and K(d) for [(3)H] paroxetine binding (p = 0.006). In general, there was a decrease in B(max) with increasing age, which predominantly occurred between the ages 11-12 years and 16-17 years for the 5-HT(2A) receptor, and after 16-17 years of age for the serotonin uptake site. These developmental changes might have an impact on the effect of treatment with serotonergic drugs in children and adolescents. When the platelet serotonin variables investigated are employed in studies in children or adolescents, age matching or, alternatively, introduction of age control in the statistical analysis should be performed.

  18. 5-HT(2A) and mGlu2 receptor binding levels are related to differences in impulsive behavior in the Roman Low- (RLA) and High- (RHA) avoidance rat strains.

    PubMed

    Klein, A B; Ultved, L; Adamsen, D; Santini, M A; Tobeña, A; Fernandez-Teruel, A; Flores, P; Moreno, M; Cardona, D; Knudsen, G M; Aznar, S; Mikkelsen, J D

    2014-03-28

    The Roman Low- and High-Avoidance rat strains (RLA-I vs RHA-I) have been bidirectionally selected and bred according to their performance in the two-way active avoidance response in the shuttle-box test. Numerous studies have reported a pronounced divergence in emotionality between the two rat strains including differences in novelty seeking, anxiety, stress coping, and susceptibility to addictive substances. However, the underlying molecular mechanisms behind these divergent phenotypes are not known. Here, we determined impulsivity using the 5-choice serial reaction time task and levels of serotonin transporter (SERT), 5-HT(2A) and 5-HT(1A) receptor binding using highly specific radioligands ((3)H-escitalopram, (3)H-MDL100907 and (3)H-WAY100635) and mGlu2/3 receptor binding ((3)H-LY341495) using receptor autoradiography in fronto-cortical sections from RLA-I (n=8) and RHA-I (n=8) male rats. In the more impulsive RHA-I rats, 5-HT(2A), 5-HT(1A) and SERT binding in the frontal cortex was significantly higher compared to RLA-I rats. In contrast, mGlu2/3 receptor binding was decreased by 40% in RHA-I rats compared to RLA-I rats. To differentiate between mGlu2 and mGlu3 receptor protein levels, these were further studied using western blotting, which showed non-detectable levels of mGlu2 receptor protein in RHA rats, while no differences were observed for mGlu3 receptor protein levels. Collectively, these data show general congenital differences in the serotonergic system and a pronounced difference in mGlu2 receptor protein levels. We suggest that the differences in the serotonergic system may mediate some of the phenotypic characteristics in this strain such as hyper-impulsivity and susceptibility to drug addiction. PMID:24412375

  19. The Combination of Marketed Antagonists of α1b-Adrenergic and 5-HT2A Receptors Inhibits Behavioral Sensitization and Preference to Alcohol in Mice: A Promising Approach for the Treatment of Alcohol Dependence

    PubMed Central

    Trovero, Fabrice; David, Sabrina; Bernard, Philippe; Puech, Alain; Bizot, Jean-Charles; Tassin, Jean-Pol

    2016-01-01

    Alcohol-dependence is a chronic disease with a dramatic and expensive social impact. Previous studies have indicated that the blockade of two monoaminergic receptors, α1b-adrenergic and 5-HT2A, could inhibit the development of behavioral sensitization to drugs of abuse, a hallmark of drug-seeking and drug-taking behaviors in rodents. Here, in order to develop a potential therapeutic treatment of alcohol dependence in humans, we have blocked these two monoaminergic receptors by a combination of antagonists already approved by Health Agencies. We show that the association of ifenprodil (1 mg/kg) and cyproheptadine (1 mg/kg) (α1-adrenergic and 5-HT2 receptor antagonists marketed as Vadilex ® and Periactine ® in France, respectively) blocks behavioral sensitization to amphetamine in C57Bl6 mice and to alcohol in DBA2 mice. Moreover, this combination of antagonists inhibits alcohol intake in mice habituated to alcohol (10% v/v) and reverses their alcohol preference. Finally, in order to verify that the effect of ifenprodil was not due to its anti-NMDA receptors property, we have shown that a combination of prazosin (0.5 mg/kg, an α1b-adrenergic antagonist, Mini-Press ® in France) and cyproheptadine (1 mg/kg) could also reverse alcohol preference. Altogether these findings strongly suggest that combined prazosin and cyproheptadine could be efficient as a therapy to treat alcoholism in humans. Finally, because α1b-adrenergic and 5-HT2A receptors blockade also inhibits behavioral sensitization to psychostimulants, opioids and tobacco, it cannot be excluded that this combination will exhibit some efficacy in the treatment of addiction to other abused drugs. PMID:26968030

  20. 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

  1. Effects of the 5-HT₆ receptor antagonists SB-399885 and RO-4368554 and of the 5-HT(2A) receptor antagonist EMD 281014 on sleep and wakefulness in the rat during both phases of the light-dark cycle.

    PubMed

    Monti, Jaime M; Jantos, Héctor

    2011-01-01

    The effects of the 5-HT₆ receptor antagonists SB-399885 (2.5, 5 and 10 mg/kg) and RO-4368554 (2.5, 5 and 10 mg/kg) and of the 5-HT(2A) receptor antagonist EMD 281014 (2.5, 5 and 10 mg/kg) were studied in rats implanted for chronic sleep procedures. Administration of 10 mg/kg SB-399885, i.p., to rats 2 h after the beginning of the light phase of the light-dark cycle caused a significant increase of wakefulness (W) and a reduction of slow wave sleep (SWS), REM sleep (REMS) and the number of REM periods during 6-h recording sessions. Light sleep was increased after the whole range of doses. The increase of W and reduction of SWS and REMS occurred predominantly during the first 2-h period whereas light sleep was augmented over the first and the second 2-h recording periods. Injection of RO-4368554 (10 mg/kg, i.p.) 2 h after the beginning of the light period significantly increased W and reduced SWS and REMS during the first 2-h recording period. Administration of EMD 281014 (10 mg/kg, i.p.) during the light phase significantly increased SWS and reduced light sleep during 6-h sessions. REMS and the number of REM period were reduced with the entire range of doses. The reduction of REMS and light sleep and the increase of SWS occurred predominantly during the first and the second 2-h of recording, respectively. Injection of SB-399885 (10 mg/kg, i.p.) 2 h after the beginning of the dark period induced a significant reduction of REMS during the first 2-h of recording. In contrast, RO-4368554 did not modify values corresponding to sleep variables during the dark period. Treatment with EMD 281014 (2.5-10 mg/kg, i.p.) during the dark phase significantly increased SWS during the second 2-h period. Our study supports the proposal that blockade of postsynaptic 5-HT₆ receptors with systemic administration of SB-399885 and RO-4368554 increases W and reduces SWS and REMS during the light phase of the sleep-wake cycle. SB-399885 also induces a suppression of REMS during the dark

  2. Distinct effect of 5-HT1A and 5-HT2A receptors in the medial nucleus of the amygdala on tonic immobility behavior.

    PubMed

    de Paula, Bruna Balbino; Leite-Panissi, Christie Ramos Andrade

    2016-07-15

    The tonic immobility (TI) response is an innate fear behavior associated with intensely dangerous situations, exhibited by many species of invertebrate and vertebrate animals. In humans, it is possible that TI predicts the severity of posttraumatic stress disorder symptoms. This behavioral response is initiated and sustained by the stimulation of various groups of neurons distributed in the telencephalon, diencephalon and brainstem. Previous research has found the highest Fos-IR in the posteroventral part of the medial nucleus of the amygdala (MEA) during TI behavior; however, the neurotransmission of this amygdaloid region involved in the modulation of this innate fear behavior still needs to be clarified. Considering that a major drug class used for the treatment of psychopathology is based on serotonin (5-HT) neurotransmission, we investigated the effects of serotonergic receptor activation in the MEA on the duration of TI. The results indicate that the activation of the 5HT1A receptors or the blocking of the 5HT2 receptors of the MEA can promote a reduction in fear and/or anxiety, consequently decreasing TI duration in guinea pigs. In contrast, blocking the 5HT1A receptors or activating the 5HT2 receptors in this amygdalar region increased the TI duration, suggesting an increase in fear and/or anxiety. These alterations do not appear to be due to a modification of spontaneous motor activity, which might non-specifically affect TI duration. Thus, these results suggest a distinct role of the 5HT receptors in the MEA in innate fear modulation. PMID:27150816

  3. Hallucinogen-like effects of 2-([2-(4-cyano-2,5-dimethoxyphenyl) ethylamino]methyl)phenol (25CN-NBOH), a novel N-benzylphenethylamine with 100-fold selectivity for 5-HT2A receptors, in mice

    PubMed Central

    Gray, Bradley W.; Bailey, Jessica M.; Smith, Douglas; Hansen, Martin; Kristensen, Jesper L.

    2014-01-01

    Rationale 2-([2-(4-cyano-2,5-dimethoxyphenyl)ethylamino]methyl)phenol (25CN-NBOH) is structurally similar to N-benzyl substituted phenethylamine hallucinogens currently emerging as drugs of abuse. 25CN-NBOH exhibits dramatic selectivity for 5-HT2A receptors in vitro, but has not been behaviorally characterized. Objective 25CN-NBOH was compared to the traditional phenethylamine hallucinogen R(−)-2,5-dimethoxy-4-iodoamphetamine (DOI) using mouse models of drug-elicited head twitch behavior and drug discrimination. Methods Drug-elicited head twitches were quantified for 10 min following administration of various doses of either DOI or 25CN-NBOH, with and without pretreatments of 0.01 mg/kg 5-HT2A antagonist M100907 or 3.0 mg/kg 5-HT2C antagonist RS102221. The capacity of 25CN-NBOH to attenuate DOI-elicited head twitch was also investigated. Mice were trained to discriminate DOI or M100907 from saline, and 25CN-NBOH was tested for generalization. Results 25CN-NBOH induced a head twitch response in the mouse that was lower in magnitude than that of DOI, blocked by M100907, but not altered by RS102221. DOI-elicited head twitch was dose-dependently attenuated by 25CN-NBOH pretreatment. 25CN-NBOH produced an intermediate degree of generalization (55%) for the DOI training dose, and these interoceptive effects were attenuated by M100907. Finally, 25CN-NBOH did not generalize to M100907 at any dose, but ketanserin fully substituted in these animals. Conclusions 25CN-NBOH was behaviorally active, but less effective than DOI in two mouse models of hallucinogenic effects. The effectiveness with which M100907 antagonized the behavioral actions of 25CN-NBOH strongly suggests that the 5-HT2A receptor is an important site of agonist action for this compound in vivo. PMID:25224567

  4. Effects of central activation of serotonin 5-HT2A/2C or dopamine D2/3 receptors on the acute and repeated effects of clozapine in the conditioned avoidance response test

    PubMed Central

    Feng, Min; Gao, Jun; Sui, Nan; Li, Ming

    2014-01-01

    Rationale: Acute administration of clozapine (a gold standard of atypical antipsychotics) disrupts avoidance response in rodents, while repeated administration often causes a tolerance effect. Objective: The present study investigated the neuroanatomical basis and receptor mechanisms of acute and repeated effects of clozapine treatment in the conditioned avoidance response test in male Sprague-Dawley rats. Methods: DOI (2,5-dimethoxy-4-iodo-amphetamine, a preferential 5-HT2A/2C agonist) or quinpirole (a preferential dopamine D2/3 agonist) was microinjected into the medial prefrontal cortex (mPFC) or nucleus accumbens shell (NAs), and their effects on the acute and long-term avoidance-disruptive effect of clozapine were tested. Results: Intra-mPFC microinjection of quinpirole enhanced the acute avoidance disruptive effect of clozapine (10 mg/kg, sc), while DOI microinjections reduced it marginally. Repeated administration of clozapine (10 mg/kg, sc) daily for 5 days caused a progressive decrease in its inhibition of avoidance responding, indicating tolerance development. Intra-mPFC microinjection of DOI at 25.0 (but not 5.0) μg/side during this period completely abolished the expression of clozapine tolerance. This was indicated by the finding that clozapine-treated rats centrally infused with 25.0 μg/side DOI did not show higher levels of avoidance responses than the vehicle-treated rats in the clozapine challenge test. Microinjection of DOI into the mPFC immediately before the challenge test also decreased the expression of clozapine tolerance. Conclusions: Acute behavioral effect of clozapine can be enhanced by activation of the D2/3 receptors in the mPFC. Clozapine tolerance expression relies on the neuroplasticity initiated by its antagonist action against 5-HT2A/2C receptors in the mPFC. PMID:25288514

  5. D-serine deficiency attenuates the behavioral and cellular effects induced by the hallucinogenic 5-HT(2A) receptor agonist DOI.

    PubMed

    Santini, Martin A; Balu, Darrick T; Puhl, Matthew D; Hill-Smith, Tiffany E; Berg, Alexandra R; Lucki, Irwin; Mikkelsen, Jens D; Coyle, Joseph T

    2014-02-01

    Both the serotonin and glutamate systems have been implicated in the pathophysiology of schizophrenia, as well as in the mechanism of action of antipsychotic drugs. Psychedelic drugs act through the serotonin 2A receptor (5-HT2AR), and elicit a head-twitch response (HTR) in mice, which directly correlates to 5-HT2AR activation and is absent in 5-HT2AR knockout mice. The precise mechanism of this response remains unclear, but both an intrinsic cortico-cortical pathway and a thalamo-cortical pathway involving glutamate release have been proposed. Here, we used a genetic model of NMDAR hypofunction, the serine racemase knockout (SRKO) mouse, to explore the role of glutamatergic transmission in regulating 5-HT2AR-mediated cellular and behavioral responses. SRKO mice treated with the 5-HT2AR agonist (±)-2,5-dimethoxy-4-iodoamphetamine (DOI) showed a clearly diminished HTR and lower induction of c-fos mRNA. These altered functional responses in SRKO mice were not associated with changes in cortical or hippocampal 5-HT levels or in 5-HT2AR and metabotropic glutamate-2 receptor (mGluR2) mRNA and protein expression. Together, these findings suggest that D-serine-dependent NMDAR activity is involved in mediating the cellular and behavioral effects of 5-HT2AR activation.

  6. Dual role of serotonin in the acquisition and extinction of reward-driven learning: involvement of 5-HT1A, 5-HT2A and 5-HT3 receptors.

    PubMed

    Frick, Luciana Romina; Bernardez-Vidal, Micaela; Hocht, Christian; Zanutto, Bonifacio Silvano; Rapanelli, Maximiliano

    2015-01-15

    Serotonin (5-HT) has been proposed as a possible encoder of reward. Nevertheless, the role of this neurotransmitter in reward-based tasks is not well understood. Given that the major serotonergic circuit in the rat brain comprises the dorsal raphe nuclei and the medial prefrontal cortex (mPFC), and because the latter structure is involved in the control of complex behaviors and expresses 1A (5-HT1A), 2A (5-HT2A), and 3 (5-HT3) receptors, the aim was to study the role of 5-HT and of these receptors in the acquisition and extinction of a reward-dependent operant conditioning task. Long Evans rats were trained in an operant conditioning task while receiving fluoxetine (serotonin reuptake inhibitor, 10mg/kg), tianeptine (serotonin reuptake enhancer, 10mg/kg), buspirone (5-HT1A partial agonist, 10mg/kg), risperidone (5-HT2A antagonist, 1mg/kg), ondansetron (5-HT3 antagonist, 2mg/kg) or vehicle. Then, animals that acquired the operant conditioning without any treatment were trained to extinct the task in the presence of the pharmacological agents. Fluoxetine impaired acquisition but improved extinction. Tianeptine administration induced the opposite effects. Buspirone induced a mild deficit in acquisition and had no effects during the extinction phase. Risperidone administration resulted in learning deficits during the acquisition phase, although it promoted improved extinction. Ondansetron treatment showed a deleterious effect in the acquisition phase and an overall improvement in the extinction phase. These data showed a differential role of 5-HT in the acquisition and extinction of an operant conditioning task, suggesting that it may have a dual function in reward encoding. PMID:24949809

  7. Binding of [3H]paroxetine to serotonin uptake sites and of [3H]lysergic acid diethylamide to 5-HT2A receptors in platelets from women with premenstrual dysphoric disorder during gonadotropin releasing hormone treatment.

    PubMed

    Bixo, M; Allard, P; Bäckström, T; Mjörndal, T; Nyberg, S; Spigset, O; Sundström-Poromaa, I

    2001-08-01

    Changes in serotonergic parameters have been reported in psychiatric conditions such as depression but also in the premenstrual dysphoric disorder (PMDD). In addition, hormonal effects on serotonergic activity have been established. In the present study, binding of [3H]paroxetine to platelet serotonin uptake sites and binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin (5-HT)2A receptors were studied in patients with PMDD treated with a low dose of a gonadotropin releasing hormone (GnRH) agonist (buserelin) or placebo and compared to controls. The PMDD patients were relieved of premenstrual symptoms like depression and irritability during buserelin treatment. The number of [3H]paroxetine binding sites (Bmax) were significantly higher in the follicular phase in untreated PMDD patients compared to controls. When treated with buserelin the difference disappeared. No differences in [3H]LSD binding between the three groups were shown. The present study demonstrated altered platelet [3H]paroxetine binding characteristics in women with PMDD compared to controls. Furthermore, [3H]paroxetine binding was affected by PMDD treatment with a low dose of buserelin. The results are consistent with the hypothesis that changes in serotonergic transmission could be a trait in the premenstrual dysphoric disorder.

  8. Extending David Horrobin's membrane phospholipid theory of schizophrenia: overactivity of cytosolic phospholipase A(2) in the brain is caused by overdrive of coupled serotonergic 5HT(2A/2C) receptors in response to stress.

    PubMed

    Eggers, Arnold E

    2012-12-01

    David Horrobin's membrane phospholipid theory of schizophrenia has held up well over time because his therapeutic prediction that dietary supplementation with eicosapentaenoic acid (EPA) would have a therapeutic effect has been partially verified and undergoes continued testing. In the final version of his theory, he hypothesized that there was hyperactivity of phosphoslipase A(2) (PLA(2)) or a related enzyme but did not explain how the hyperactivity came about. It is known that serotonergic 5HT(2A/2C) receptors are coupled to PLA(2), which hydrolyzes both arachidonic acid (AA) and EPA from diacylglycerides at the sn-2 position. In this paper, Horrobin's theory is combined with a previously published theory of chronic stress in which it was hypothesized that a disinhibited dorsal raphe nucleus, the principal nucleus of the serotonergic system, can organize the neuropathology of diseases such as migraine, hypertension, and the metabolic syndrome. The new or combined theory is that schizophrenia is a disease of chronic stress in which a disinhibited DRN causes widespread serotonergic overdrive in the cerebral cortex. This in turn causes overdrive of cPLA(2) and both central and peripheral depletion of AA and EPA. Because EPA is present in smaller amounts, it falls below threshold for maintaining an intracellular balance between AA-derived and EPA-derived second messenger cascades, which leads to abnormal patterns of neuronal firing. There are two causes of neuronal dysfunction: the disinhibited DRN and EPA depletion. Schizophrenia is statistically associated with metabolic syndrome, hypertension, and migraine because they form a cluster of diseases with similar pathophysiology. The theory provides an explanation for both the central and peripheral phospholipid abnormalities in schizophrenia. It also explains the role of stress in schizophrenia, elevated serum PLA(2) activity in schizophrenia, the relationship between untreated schizophrenia and metabolic syndrome

  9. The serotonergic hallucinogen 5-methoxy-N,N-dimethyltryptamine disrupts cortical activity in a regionally-selective manner via 5-HT(1A) and 5-HT(2A) receptors.

    PubMed

    Riga, Maurizio S; Bortolozzi, Analia; Campa, Letizia; Artigas, Francesc; Celada, Pau

    2016-02-01

    5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural hallucinogen, acting as a non-selective serotonin 5-HT(1A)/5-HT(2A)-R agonist. Psychotomimetic agents such as the non-competitive NMDA-R antagonist phencyclidine and serotonergic hallucinogens (DOI and 5-MeO-DMT) disrupt cortical synchrony in the low frequency range (<4 Hz) in rat prefrontal cortex (PFC), an effect reversed by antipsychotic drugs. Here we extend these observations by examining the effect of 5-MeO-DMT on low frequency cortical oscillations (LFCO, <4 Hz) in PFC, visual (V1), somatosensory (S1) and auditory (Au1) cortices, as well as the dependence of these effects on 5-HT(1A)-R and 5-HT(2A)-R, using wild type (WT) and 5-HT(2A)-R knockout (KO2A) anesthetized mice. 5-MeO-DMT reduced LFCO in the PFC of WT and KO2A mice. The effect in KO2A mice was fully prevented by the 5-HT(1A)-R antagonist WAY-100635. Systemic and local 5-MeO-DMT reduced 5-HT release in PFC mainly via 5-HT(1A)-R. Moreover, 5-MeO-DMT reduced LFCO in S1, Au1 and V1 of WT mice and only in V1 of KO2A mice, suggesting the involvement of 5-HT(1A)-R activation in the 5-MeO-DMT-induced disruption of V1 activity. In addition, antipsychotic drugs reversed 5-MeO-DMT effects in WT mice. The present results suggest that the hallucinogen action of 5-MeO-DMT is mediated by simultaneous alterations of the activity of sensory (S1, Au1, V1) and associative (PFC) cortical areas, also supporting a role of 5-HT(1A)-R stimulation in V1 and PFC, in addition to the well-known action on 5-HT(2A)-R. Moreover, the reversal by antipsychotic drugs of 5-MeO-DMT effects adds to previous literature supporting the usefulness of the present model in antipsychotic drug development.

  10. Synthesis and Structure–Activity Relationships of N-Benzyl Phenethylamines as 5-HT2A/2C Agonists

    PubMed Central

    2014-01-01

    N-Benzyl substitution of 5-HT2A receptor agonists of the phenethylamine structural class of psychedelics (such as 4-bromo-2,5-dimethoxyphenethylamine, often referred to as 2C-B) confer a significant increase in binding affinity as well as functional activity of the receptor. We have prepared a series of 48 compounds with structural variations in both the phenethylamine and N-benzyl part of the molecule to determine the effects on receptor binding affinity and functional activity at 5-HT2A and 5-HT2C receptors. The compounds generally had high affinity for the 5-HT2A receptor with 8b having the highest affinity at 0.29 nM but with several other compounds also exhibiting subnanomolar binding affinities. The functional activity of the compounds was distributed over a wider range with 1b being the most potent at 0.074 nM. Most of the compounds exhibited low to moderate selectivity (1- to 40-fold) for the 5-HT2A receptor in the binding assays, although one compound 6b showed an impressive 100-fold selectivity for the 5-HT2A receptor. In the functional assay, selectivity was generally higher with 1b being more than 400-fold selective for the 5-HT2A receptor. PMID:24397362

  11. Heterocomplex formation of 5-HT2A-mGlu2 and its relevance for cellular signaling cascades.

    PubMed

    Delille, Hannah K; Becker, Judith M; Burkhardt, Sabrina; Bleher, Barbara; Terstappen, Georg C; Schmidt, Martin; Meyer, Axel H; Unger, Liliane; Marek, Gerard J; Mezler, Mario

    2012-06-01

    Dopamine, serotonin and glutamate play a role in the pathophysiology of schizophrenia. In the brain a functional crosstalk between the serotonin receptor 5-HT(2A) and the metabotropic glutamate receptor mGlu(2) has been demonstrated. Such a crosstalk may be mediated indirectly through neuronal networks or directly by receptor oligomerization. A direct link of the 5-HT(2A)-mGlu(2) heterocomplex formation to receptor function, i.e. to intracellular signaling, has not been fully demonstrated yet. Here we confirm the formation of 5-HT(2A)-mGlu(2) heterocomplexes using quantitative Snap/Clip-tag based HTRF methods. Additionally, mGlu(2) formed complexes with 5-HT(2B) and mGlu(5) but not 5-HT(2C) indicating that complex formation is not specific to the 5-HT(2A)-mGlu(2) pair. We studied the functional consequences of the 5-HT(2A)-mGlu(2) heterocomplex addressing cellular signaling pathways. Co-expression of receptors in HEK-293 cells had no relevant effects on signaling mediated by the individual receptors when mGlu(2) agonists, antagonists and PAMs, or 5-HT(2A) hallucinogenic and non-hallucinogenic agonists and antagonists were used. Hallucinogenic 5-HT(2A) agonists induced signaling through G(q/11), but not G(i) and thus did not lead to modulation of intracellular cAMP levels. In membranes of the medial prefrontal cortex [(3)H]-LY341495 binding competition of mGlu(2/3) agonist LY354740 was not influenced by 2,5-dimethoxy-4-iodoamphetamine (DOI). Taken together, the formation of GPCR heterocomplexes does not necessarily translate into second messenger effects. These results do not put into question the well-documented functional cross-talk of the two receptors in the brain, but do challenge the biological relevance of the 5-HT(2A)-mGlu(2) heterocomplex.

  12. Hallucinogenic 5-HT2AR agonists LSD and DOI enhance dopamine D2R protomer recognition and signaling of D2-5-HT2A heteroreceptor complexes.

    PubMed

    Borroto-Escuela, Dasiel O; Romero-Fernandez, Wilber; Narvaez, Manuel; Oflijan, Julia; Agnati, Luigi F; Fuxe, Kjell

    2014-01-01

    Dopamine D2LR-serotonin 5-HT2AR heteromers were demonstrated in HEK293 cells after cotransfection of the two receptors and shown to have bidirectional receptor-receptor interactions. In the current study the existence of D2L-5-HT2A heteroreceptor complexes was demonstrated also in discrete regions of the ventral and dorsal striatum with in situ proximity ligation assays (PLA). The hallucinogenic 5-HT2AR agonists LSD and DOI but not the standard 5-HT2AR agonist TCB2 and 5-HT significantly increased the density of D2like antagonist (3)H-raclopride binding sites and significantly reduced the pKiH values of the high affinity D2R agonist binding sites in (3)H-raclopride/DA competition experiments. Similar results were obtained in HEK293 cells and in ventral striatum. The effects of the hallucinogenic 5-HT2AR agonists on D2R density and affinity were blocked by the 5-HT2A antagonist ketanserin. In a forskolin-induced CRE-luciferase reporter gene assay using cotransfected but not D2R singly transfected HEK293 cells DOI and LSD but not TCB2 significantly enhanced the D2LR agonist quinpirole induced inhibition of CRE-luciferase activity. Haloperidol blocked the effects of both quinpirole alone and the enhancing actions of DOI and LSD while ketanserin only blocked the enhancing actions of DOI and LSD. The mechanism for the allosteric enhancement of the D2R protomer recognition and signalling observed is likely mediated by a biased agonist action of the hallucinogenic 5-HT2AR agonists at the orthosteric site of the 5-HT2AR protomer. This mechanism may contribute to the psychotic actions of LSD and DOI and the D2-5-HT2A heteroreceptor complex may thus be a target for the psychotic actions of hallunicogenic 5-HT2A agonists.

  13. The influence of 5-HT(2A) activity on a 5-HT(2C) specific in vivo assay used for early identification of multiple acting SERT and 5-HT(2C) receptor ligands.

    PubMed

    Éliás, Olivér; Nógrádi, Katalin; Domány, György; Szakács, Zoltán; Kóti, János; Szántay, Csaba; Tarcsay, Ákos; Keserű, György M; Gere, Anikó; Kiss, Béla; Kurkó, Dalma; Kolok, Sándor; Némethy, Zsolt; Kapui, Zoltán; Hellinger, Éva; Vastag, Mónika; Sághy, Katalin; Kedves, Rita; Gyertyán, István

    2016-02-01

    As a result of our exploratory programme aimed at elaborating dually acting compounds towards the serotonin (5-HT) transporter (SERT) and the 5-HT2C receptor a novel series of 3-amino-1-phenylpropoxy substituted diphenylureas was identified. From that collection two promising compounds (2 and 3) exhibiting highest 5-HT2C receptor affinity strongly inhibited the 5-HT2C receptor agonist 1-(3-chlorophenyl)piperazine (mCPP) induced hypomotility in mice. In further pursuance of that objective (2-aminoethyl)(benzyl)sulfamoyl diphenylureas and diphenylpiperazines have also been elaborated. Herein we report the synthesis of potent multiple-acting compounds from this new class. However, when two optimized representatives (6 and 14) possessing the desired in vitro profile were tested neither reduced the motor activity of mCPP treated animals. Comparative albeit limited in vitro structure-activity relationship (SAR) analysis and detailed in vivo studies are discussed and explanation for their intricate behaviour is proposed.

  14. 4-Fluorosulfonylpiperidines: selective 5-HT2A ligands for the treatment of insomnia.

    PubMed

    Fish, L Rebecca; Gilligan, Myra T; Humphries, Alexander C; Ivarsson, Magnus; Ladduwahetty, Tammy; Merchant, Kevin J; O'Connor, Desmond; Patel, Smita; Philipps, Elisabeth; Vargas, Hugo M; Hutson, Peter H; MacLeod, Angus M

    2005-08-15

    Incorporation of fluorine at the 4-position of an existing series of sulfonyl piperidine 5-HT2A antagonists gave compounds with increased selectivity over the IKr potassium channel. This work led to the identification of 3b, a compound that gave no increase in QTc in the anesthetized dog up to plasma levels as high as 148 microM. Furthermore, 3b has been shown to increase slow-wave sleep bout duration and to decrease the number of awakenings in rats, indicating the potential utility of 5-HT2A antagonists in the treatment of insomnia.

  15. Molecular Determinants for Ligand Binding at Serotonin 5-HT2A and 5-HT2C GPCRs: Experimental Affinity Results Analyzed by Molecular Modeling and Ligand Docking Studies

    PubMed Central

    Sakhuja, Rajeev; Kondabolu, Krishnakanth; Canal, Clinton E.; Booth, Raymond G.

    2013-01-01

    Ligands that activate the serotonin 5-HT2C G protein-coupled receptor (GPCR) may be therapeutic for psychoses, addiction, and other neuropsychiatric disorders. Ligands that are antagonists at the closely related 5-HT2A GPCR also may treat neuropsychiatric disorders; in contrast, 5-HT2A activation may cause hallucinations. 5-HT2C-specific agonist drug design is challenging because 5-HT2 GPCRs share 80% transmembrane (TM) homology, same second messenger signaling, and no crystal structures are reported. To help delineate molecular determinants underlying differential binding and activation of 5-HT2 GPCRs, 5-HT2A, and 5-HT2C homology models were built from the β2-adrenergic GPCR crystal structure and equilibrated in a lipid phosphatidyl choline bilayer performing molecular dynamics simulations. Ligand docking studies at the 5-HT2 receptor models were conducted with the (2R, 4S)- and (2S, 4R)-enantiomers of the novel 5-HT2C agonist/5-HT2A/2B antagonist trans-4-phenyl-N,N-dimethyl-2-aminotetralin (PAT) and its 4′-chlorophenyl congners. Results indicate PAT–5-HT2 molecular interactions especially in TM domain V are important for the (2R, 4S) enantiomer, whereas, TM domain VI and VII interactions are more important for the (2S, 4R) enantiomer. PMID:23913978

  16. 1,4-Disubstituted aromatic piperazines with high 5-HT2A/D2 selectivity: Quantitative structure-selectivity investigations, docking, synthesis and biological evaluation.

    PubMed

    Möller, Dorothee; Salama, Ismail; Kling, Ralf C; Hübner, Harald; Gmeiner, Peter

    2015-09-15

    Simultaneous targeting of dopamine D2 and 5-HT2A receptors for the treatment of schizophrenia is one key feature of typical and atypical antipsychotics. In most of the top-selling antipsychotic drugs like aripiprazole and risperidone, high affinity to both receptors can be attributed to the presence of 1,4-disubstituted aromatic piperazines or piperidines as primary receptor recognition elements. Taking advantage of our in-house library of phenylpiperazine-derived dopamine receptor ligands and experimental data, we established highly significant CoMFA and CoMSIA models for the prediction of 5-HT2A over D2 selectivity. Subsequently, the models were applied to identify the selective candidates 55-57 from our newly synthesized library of GPCR ligands comprising a pyrazolo[1,5-a]pyridine head group and a 1,2,3-triazole based linker unit. The test compound 57 showed subnanomolar a Ki value (0.64 nM) for 5-HT2A and more than 10- and 30-fold selectivity over the dopamine receptor isoforms D2S and D2L, respectively. PMID:26299826

  17. Effects of the 5-HT2A agonist psilocybin on mismatch negativity generation and AX-continuous performance task: implications for the neuropharmacology of cognitive deficits in schizophrenia.

    PubMed

    Umbricht, Daniel; Vollenweider, Franz X; Schmid, Liselotte; Grübel, Claudia; Skrabo, Anja; Huber, Theo; Koller, Rene

    2003-01-01

    Previously the NMDA (N-methyl-D-aspartate) receptor (NMDAR) antagonist ketamine was shown to disrupt generation of the auditory event-related potential (ERP) mismatch negativity (MMN) and the performance of an 'AX'-type continuous performance test (AX-CPT)--measures of auditory and visual context-dependent information processing--in a similar manner as observed in schizophrenia. This placebo-controlled study investigated effects of the 5-HT(2A) receptor agonist psilocybin on the same measures in 18 healthy volunteers. Psilocybin administration induced significant performance deficits in the AX-CPT, but failed to reduce MMN generation significantly. These results indirectly support evidence that deficient MMN generation in schizophrenia may be a relatively distinct manifestation of deficient NMDAR functioning. In contrast, secondary pharmacological effects shared by NMDAR antagonists and the 5-HT(2A) agonist (ie disruption of glutamatergic neurotransmission) may be the mechanism underlying impairments in AX-CPT performance observed during both psilocybin and ketamine administration. Comparable deficits in schizophrenia may result from independent dysfunctions of 5-HT(2A) and NMDAR-related neurotransmission.

  18. 5-HT2A Gene Variants Moderate the Association between PTSD and Reduced Default Mode Network Connectivity.

    PubMed

    Miller, Mark W; Sperbeck, Emily; Robinson, Meghan E; Sadeh, Naomi; Wolf, Erika J; Hayes, Jasmeet P; Logue, Mark; Schichman, Steven A; Stone, Angie; Milberg, William; McGlinchey, Regina

    2016-01-01

    The default mode network (DMN) has been used to study disruptions of functional connectivity in a wide variety of psychiatric and neurological conditions, including posttraumatic stress disorder (PTSD). Studies indicate that the serotonin system exerts a modulatory influence on DMN connectivity; however, no prior study has examined associations between serotonin receptor gene variants and DMN connectivity in either clinical or healthy samples. We examined serotonin receptor single nucleotide polymorphisms (SNPs), PTSD, and their interactions for association with DMN connectivity in 134 White non-Hispanic veterans. We began by analyzing candidate SNPs identified in prior meta-analyses of relevant psychiatric traits and found that rs7997012 (an HTR2A SNP), implicated previously in anti-depressant medication response in the Sequenced Treatment Alternatives for Depression study (STAR(*)D; McMahon et al., 2006), interacted with PTSD to predict reduced connectivity between the posterior cingulate cortex (PCC) and the right medial prefrontal cortex and right middle temporal gyrus (MTG). rs130058 (HTR1B) was associated with connectivity between the PCC and right angular gyrus. We then expanded our analysis to 99 HTR1B and HTR2A SNPs and found two HTR2A SNPs (rs977003 and rs7322347) that significantly moderated the association between PTSD severity and the PCC-right MTG component of the DMN after correcting for multiple testing. Finally, to obtain a more precise localization of the most significant SNP × PTSD interaction, we performed a whole cortex vertex-wise analysis of the rs977003 effect. This analysis revealed the locus of the pre-frontal effect to be in portions of the superior frontal gyrus, while the temporal lobe effect was centered in the middle and inferior temporal gyri. These findings point to the influence of HTR2A variants on DMN connectivity and advance knowledge of the role of 5-HT2A receptors in the neurobiology of PTSD. PMID:27445670

  19. 5-HT2A Gene Variants Moderate the Association between PTSD and Reduced Default Mode Network Connectivity

    PubMed Central

    Miller, Mark W.; Sperbeck, Emily; Robinson, Meghan E.; Sadeh, Naomi; Wolf, Erika J.; Hayes, Jasmeet P.; Logue, Mark; Schichman, Steven A.; Stone, Angie; Milberg, William; McGlinchey, Regina

    2016-01-01

    The default mode network (DMN) has been used to study disruptions of functional connectivity in a wide variety of psychiatric and neurological conditions, including posttraumatic stress disorder (PTSD). Studies indicate that the serotonin system exerts a modulatory influence on DMN connectivity; however, no prior study has examined associations between serotonin receptor gene variants and DMN connectivity in either clinical or healthy samples. We examined serotonin receptor single nucleotide polymorphisms (SNPs), PTSD, and their interactions for association with DMN connectivity in 134 White non-Hispanic veterans. We began by analyzing candidate SNPs identified in prior meta-analyses of relevant psychiatric traits and found that rs7997012 (an HTR2A SNP), implicated previously in anti-depressant medication response in the Sequenced Treatment Alternatives for Depression study (STAR*D; McMahon et al., 2006), interacted with PTSD to predict reduced connectivity between the posterior cingulate cortex (PCC) and the right medial prefrontal cortex and right middle temporal gyrus (MTG). rs130058 (HTR1B) was associated with connectivity between the PCC and right angular gyrus. We then expanded our analysis to 99 HTR1B and HTR2A SNPs and found two HTR2A SNPs (rs977003 and rs7322347) that significantly moderated the association between PTSD severity and the PCC-right MTG component of the DMN after correcting for multiple testing. Finally, to obtain a more precise localization of the most significant SNP × PTSD interaction, we performed a whole cortex vertex-wise analysis of the rs977003 effect. This analysis revealed the locus of the pre-frontal effect to be in portions of the superior frontal gyrus, while the temporal lobe effect was centered in the middle and inferior temporal gyri. These findings point to the influence of HTR2A variants on DMN connectivity and advance knowledge of the role of 5-HT2A receptors in the neurobiology of PTSD. PMID:27445670

  20. Effect of GABAergic ligands on the anxiolytic-like activity of DOI (a 5-HT(2A/2C) agonist) in the four-plate test in mice.

    PubMed

    Massé, Fabienne; Hascoët, Martine; Bourin, Michel

    2007-01-01

    5-HTergic and GABAergic systems are involved in neurobiology of anxiety. Precedent studies have demonstrated that SSRIs possessed an anxiolytic-like effect in the four-plate test (FPT) at doses that did not modify spontaneous locomotor activity. This effect seems to be mediated through the activation of 5-HT(2A) postsynaptic receptors. The purpose of the present study was to examine the implication of GABA system in the anxiolytic-like activity of DOI in the FPT. To achieve this, the co-administration of DOI (5-HT(2A/2C) receptor agonists) with GABA(A) and GABA(B) receptor ligands was evaluated in the FPT. Alprazolam, diazepam and muscimol (for higher dose) potentiated the anxiolytic-like effect of DOI. Bicuculline, picrotoxin and baclofen inhibited the anxiolytic-like effect of DOI. Flumazenil and CGP 35348 had no effect on the anxiolytic-like activity of DOI. These results suggest that the GABA system seems to be strongly implicated in the anxiolytic-like activity of DOI in the FPT.

  1. Evidence for a common biological basis of the Absorption trait, hallucinogen effects, and positive symptoms: epistasis between 5-HT2a and COMT polymorphisms.

    PubMed

    Ott, Ulrich; Reuter, Martin; Hennig, Juergen; Vaitl, Dieter

    2005-08-01

    Absorption represents a disposition to experience altered states of consciousness characterized by intensively focused attention. It is correlated with hypnotic susceptibility and includes phenomena ranging from vivid perceptions and imaginations to mystical experiences. Based on the assumption that drug-induced and naturally occurring mystical experiences share common neural mechanisms, we hypothesized that Absorption is influenced by the T102C polymorphism affecting the 5-HT2a receptor, which is known to be an important target site of hallucinogens like LSD. Based on the pivotal role ascribed to the prefrontal executive control network for absorbed attention and positive symptoms in schizophrenia, it was further hypothesized that Absorption is associated with the VAL158MET polymorphism of the catechol-O-methyltransferase (COMT) gene affecting the dopaminergic neurotransmitter system. The Tellegen Absorption Scale was administered to 336 subjects (95 male, 241 female). Statistical analysis revealed that the group with the T/T genotype of the T102C polymorphism, implying a stronger binding potential of the 5-HT2a receptor, indeed had significantly higher Absorption scores (F = 10.00, P = 0.002), while no main effect was found for the COMT polymorphism. However, the interaction between T102C and COMT genotypes yielded significance (F = 3.89; P = 0.049), underlining the known functional interaction between the 5-HT and the dopaminergic system. These findings point to biological foundations of the personality trait of Absorption.

  2. Contrasting mechanisms of action and sensitivity to antipsychotics of phencyclidine versus amphetamine: importance of nucleus accumbens 5-HT2A sites for PCP-induced locomotion in the rat.

    PubMed

    Millan, M J; Brocco, M; Gobert, A; Joly, F; Bervoets, K; Rivet, J; Newman-Tancredi, A; Audinot, V; Maurel, S

    1999-12-01

    In the present study, the comparative mechanisms of action of phencyclidine (PCP) and amphetamine were addressed employing the parameter of locomotion in rats. PCP-induced locomotion (PLOC) was potently blocked by the selective serotonin (5-HT)2A vs. D2 antagonists, SR46349, MDL100,907, ritanserin and fananserin, which barely affected amphetamine-induced locomotion (ALOC). In contrast, the selective D2 vs. 5-HT2A antagonists, eticlopride, raclopride and amisulpride, preferentially inhibited ALOC vs. PLOC. The potency of these drugs and 12 multireceptorial antipsychotics in inhibiting PLOC vs. ALOC correlated significantly with affinities at 5-HT2A vs. D2 receptors, respectively. Amphetamine and PCP both dose dependently increased dialysate levels of dopamine (DA) and 5-HT in the nucleus accumbens, striatum and frontal cortex (FCX) of freely moving rats, but PCP was proportionally more effective than amphetamine in elevating levels of 5-HT vs. DA in the accumbens. Further, whereas microinjection of PCP into the accumbens elicited locomotion, its introduction into the striatum or FCX was ineffective. The action of intra-accumbens PCP, but not intra-accumbens amphetamine, was abolished by SR46349 and clozapine. Parachloroamphetamine, which depleted accumbens pools of 5-HT but not DA, likewise abolished PLOC without affecting ALOC. In contrast, intra-accumbens 6-hydroxydopamine (6-OHDA), which depleted DA but not 5-HT, abolished ALOC but only partially attenuated PLOC. In conclusion, PLOC involves (indirect) activation of accumbens-localized 5-HT2A receptors by 5-HT. PLOC is, correspondingly, more potently blocked than ALOC by antipsychotics displaying marked affinity at 5-HT2A receptors.

  3. The effects of the preferential 5-HT2A agonist psilocybin on prepulse inhibition of startle in healthy human volunteers depend on interstimulus interval.

    PubMed

    Vollenweider, Franz X; Csomor, Philipp A; Knappe, Bernhard; Geyer, Mark A; Quednow, Boris B

    2007-09-01

    Schizophrenia patients exhibit impairments in prepulse inhibition (PPI) of the startle response. Hallucinogenic 5-HT(2A) receptor agonists are used for animal models of schizophrenia because they mimic some symptoms of schizophrenia in humans and induce PPI deficits in animals. Nevertheless, one report indicates that the 5-HT(2A) receptor agonist psilocybin increases PPI in healthy humans. Hence, we investigated these inconsistent results by assessing the dose-dependent effects of psilocybin on PPI in healthy humans. Sixteen subjects each received placebo or 115, 215, and 315 microg/kg of psilocybin at 4-week intervals in a randomized and counterbalanced order. PPI at 30-, 60-, 120-, 240-, and 2000-ms interstimulus intervals (ISIs) was measured 90 and 165 min after drug intake, coinciding with the peak and post-peak effects of psilocybin. The effects of psilocybin on psychopathological core dimensions and sustained attention were assessed by the Altered States of Consciousness Rating Scale (5D-ASC) and the Frankfurt Attention Inventory (FAIR). Psilocybin dose-dependently reduced PPI at short (30 ms), had no effect at medium (60 ms), and increased PPI at long (120-2000 ms) ISIs, without affecting startle reactivity or habituation. Psilocybin dose-dependently impaired sustained attention and increased all 5D-ASC scores with exception of Auditory Alterations. Moreover, psilocybin-induced impairments in sustained attention performance were positively correlated with reduced PPI at the 30 ms ISI and not with the concomitant increases in PPI observed at long ISIs. These results confirm the psilocybin-induced increase in PPI at long ISIs and reveal that psilocybin also produces a decrease in PPI at short ISIs that is correlated with impaired attention and consistent with deficient PPI in schizophrenia.

  4. The effect of intrahippocampal injections of ritanserin (5HT2A/2C antagonist) and granisetron (5HT3 antagonist) on learning as assessed in the spatial version of the water maze.

    PubMed

    Naghdi, Nasser; Harooni, Hooman E

    2005-02-28

    5HT(2A/2C) and 5HT(3) receptors have an important role in cognitive behavior specially in spatial learning and memory but the literature concerning the role of these receptors in hippocampus in cognition remains controversial. In the present study a 5HT(2A/2C) antagonist ritanserin (0, 2, 4, 8 microg/0.5 microl) and a 5HT(3) antagonist granisetron (0.0, 0.05, 0.25, 0.5 microg/0.5 microl) were injected bilaterally into the CA1 region of rat hippocampus, 20 min before each training session in Morris Water Maze (MWM) task. Compare with control group, ritanserin (4 microg/0.5 microl) significantly reduced the escape latency and traveled distance of swimming to platform, but granisetron (0.25 microg/0.5 microl) significantly increased those parameters. Both drugs had no effect on escape latency and traveled distance of a non-spatial visual discrimination task. These results suggest a differential role of 5HT(2A/2C) and 5HT(3) receptors during spatial learning that ritanserin improves rat performance in spatial discrimination task whereas granisetron impairs it.

  5. Association study of T102C 5-HT2A polymorphism in schizophrenic patients: diagnosis, psychopathology, and suicidal behavior

    PubMed Central

    Correa, Humberto; De Marco, Luiz; Boson, Wolfanga; Nicolato, Rodrigo; Teixeira, Antó L.; Campo, Valdir R.; Romano-Silva, Marco A.

    2007-01-01

    The objective of this study was to examine the association between the serotonin (5-HT)2A gene polymorphism (102T/C) and suicidal behavior in schizophrenic inpatients. We studied 129 subjects who met the diagnostic criteria for schizophrenia according to a structured clinicai interview (MINI-PLUS), Patients underwent a semistructured interview to assess suicide attempt history and its characteristics, in addition, at least one close relative of the patient was interviewed to assess prohand and family suicidal behavior. Healthy controls were students and hospital staff members free of psychiatric and medical illness. Genotypes were determined after polymerase chain reaction amplification of the region of 5-HT2A/T102C containing the polymorphic site and digestion with the restriction enzyme Hpall, We found no association between suicidal attempt history and suicide attempt characteristics and genotypic or aileie frequencies. Suicidal behavior was also not associated with demographic or psychopathological characteristics. These results suggest that the S-HT2A gene polymorphism (102T/C) is not involved in genetic susceptibility to suicidal behavior, but further studies in a larger sample are needed. PMID:17506229

  6. Pharmacogenetic Study of Serotonin Transporter and 5HT2A Genotypes in Autism

    PubMed Central

    Najjar, Fedra; Owley, Thomas; Mosconi, Matthew W.; Jacob, Suma; Hur, Kwan; Guter, Stephen J.; Sweeney, John A.; Gibbons, Robert D; Bishop, Jeffrey R.

    2015-01-01

    Abstract Objective: The purpose of this study was to determine whether polymorphisms in the serotonin transporter (SLC6A4) and serotonin-2A receptor (HTR2A) genes are associated with response to escitalopram in patients with autism spectrum disorder (ASD). Methods: Forty-four participants with ASD were enrolled in a 6 week, forced titration, open label examination of the selective serotonin reuptake inhibitor (SSRI) escitalopram. Doses increased at weekly intervals starting at 2.5mg daily with a maximum possible dose of 20 mg daily achieved by the end of the study. If adverse events were experienced, participants subsequently received the previously tolerated dose for the duration of study. SLC6A4 (5-HTTLPR) and HTR2A (rs7997012) genotype groups were assessed in relation to treatment outcomes and drug doses. Results: Insistence on sameness and irritability symptoms significantly improved over the course of the 6 week treatment period (p<0.0001) in this open-label trial. There were no significant differences observed in the rate of symptom improvement over time across genotype groups. Similarly, dosing trajectory was not significantly associated with genotype groups. Conclusions: Previous studies have identified SLC6A4 and HTR2A associations with SSRI response in patients with depression and 5-HTTLPR (SLC6A4) associations with escitalopram response in ASD. We did not observe evidence for similar relationships in this ASD study. PMID:26262902

  7. Clonidine potentiates the effects of 5-HT1A, 5-HT1B and 5-HT2A/2C antagonists and 8-OH-DPAT in the mouse forced swimming test.

    PubMed

    Redrobe, J P; Bourin, M

    1998-08-01

    The present study was undertaken to identify the receptor subtypes involved in clonidine's ability to enhance the effects of antidepressant drugs in the mouse forced swimming test. Clonidine (0.06 mg/kg, i.p.) significantly enhanced the antidepressant-like effects of subactive doses of the 5-HT1A receptor agonist, 8-OH-DPAT (1 mg/kg, i.p.; P<0.01); the 5-HT1A receptor antagonist, NAN 190 (0.5 mg/kg, i.p.; P<0.01); the 5-HT1A/1B autoreceptor antagonist, (+/-) pindolol (32 mg/kg, i.p.; P<0.01); the 5-HT2A/2C receptor antagonist, ritanserin (4 mg/kg, i.p.; P<0.01). Pretreatment with clonidine failed to increase mobility when administered in combination with the 5-HT1B receptor agonist, RU 24969 (1 mg/kg, i.p.) or the 5-HT2A receptor antagonist, ketanserin (8 mg/kg, i.p.). In conclusion, clonidine-induced anti-immobility effects are more likely mediated by 5-HT1A and 5-HT2C receptors, as well as alpha-2-adrenergic autoreceptors situated on noradrenergic neurones. The results of the present study also demonstrate that serotonergic receptor function can influence alpha-2-adrenoreceptor mediated responses in the mouse forced swimming test.

  8. Modulating the rate and rhythmicity of perceptual rivalry alternations with the mixed 5-HT2A and 5-HT1A agonist psilocybin.

    PubMed

    Carter, Olivia L; Pettigrew, John D; Hasler, Felix; Wallis, Guy M; Liu, Guang B; Hell, Daniel; Vollenweider, Franz X

    2005-06-01

    Binocular rivalry occurs when different images are presented simultaneously to corresponding points within the left and right eyes. Under these conditions, the observer's perception will alternate between the two perceptual alternatives. Motivated by the reported link between the rate of perceptual alternations, symptoms of psychosis and an incidental observation that the rhythmicity of perceptual alternations during binocular rivalry was greatly increased 10 h after the consumption of LSD, this study aimed to investigate the pharmacology underlying binocular rivalry and to explore the connection between the timing of perceptual switching and psychosis. Psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine, PY) was chosen for the study because, like LSD, it is known to act as an agonist at serotonin (5-HT)1A and 5-HT2A receptors and to produce an altered state sometimes marked by psychosis-like symptoms. A total of 12 healthy human volunteers were tested under placebo, low-dose (115 microg/kg) and high-dose (250 microg/kg) PY conditions. In line with predictions, under both low- and high-dose conditions, the results show that at 90 min postadministration (the peak of drug action), rate and rhythmicity of perceptual alternations were significantly reduced from placebo levels. Following the 90 min testing period, the perceptual switch rate successively increased, with some individuals showing increases well beyond pretest levels at the final testing, 360 min postadministration. However, as some subjects had still not returned to pretest levels by this time, the mean phase duration at 360 min was not found to differ significantly from placebo. Reflecting the drug-induced changes in rivalry phase durations, subjects showed clear changes in psychological state as indexed by the 5D-ASC (altered states of consciousness) rating scales. This study suggests the involvement of serotonergic pathways in binocular rivalry and supports the previously proposed role of a brainstem

  9. The serotonin 2C receptor potently modulates the head-twitch response in mice induced by a phenethylamine hallucinogen

    PubMed Central

    Canal, Clinton E.; Olaghere da Silva, Uade B.; Gresch, Paul J.; Watt, Erin E.; Sanders-Bush, Elaine

    2010-01-01

    Rationale Hallucinogenic serotonin 2A (5-HT2A) receptor partial agonists, such as (±)-1-(2,5-dimethoxy-4-iodo-phenyl)-2-aminopropane hydrochloride (DOI), induce a frontal cortex-dependent head-twitch response (HTR) in rodents, a behavioral proxy of a hallucinogenic response that is blocked by 5-HT2A receptor antagonists. In addition to 5-HT2A receptors, DOI and most other serotonin-like hallucinogens have high affinity and potency as partial agonists at 5-HT2C receptors. Objectives We tested for involvement of 5-HT2C receptors in the HTR induced by DOI. Results Comparison of 5-HT2C receptor knockout and wild-type littermates revealed an approximately 50% reduction in DOI-induced HTR in knockout mice. Also, pretreatment with either the 5-HT2C receptor antagonist SB206553 or SB242084 eradicated a twofold difference in DOI-induced HTR between the standard inbred mouse strains C57BL/6J and DBA/2J, and decreased the DOI-induced HTR by at least 50% in both strains. None of several measures of 5-HT2A receptors in frontal cortex explained the strain difference, including 5-HT2A receptor density, Gαq or Gαi/o protein levels, phospholipase C activity, or DOI-induced expression of Egr1 and Egr2. 5-HT2C receptor density in the brains of C57BL/6J and DBA/2J was also equivalent, suggesting that 5-HT2C receptor-mediated intracellular signaling or other physiological modulators of the HTR may explain the strain difference in response to DOI. Conclusions We conclude that the HTR to DOI in mice is strongly modulated by 5-HT2C receptor activity. This novel finding invites reassessment of hallucinogenic mechanisms involving 5-HT2 receptors. PMID:20165943

  10. The Relationship Between Single Nucleotide Polymorphisms in 5-HT2A Signal Transduction-Related Genes and the Response Efficacy to Selective Serotonin Reuptake Inhibitor Treatments in Chinese Patients with Major Depressive Disorder

    PubMed Central

    Li, Heng-Fen; Yu, Xue; He, Cha-Ye; Kou, Shao-Jie; Cao, Su-Xia

    2012-01-01

    Objective: To explore the possible relationship between six single nucleotide polymorphisms (SNPs) (rs6311 and rs6305 of 5-HT2A, rs5443 of Gβ3, rs2230739 of ACDY9, rs1549870 of PDE1A and rs255163 of CREB1, which are all related with 5-HT2A the signal transduction pathway) and the response efficacy to selective serotonin reuptake inhibitor (SSRI) treatments in major depressive disorder (MDD) Chinese. Methods: This study included 194 depressed patients to investigate the influence of 6 polymorphisms in 5-HT2A signal transduction-related genes on the efficacy of SSRIs assessed over 1 year. The efficacies of SSRIs on 194 MDD patients were evaluated in an 8-week open-trial study. Over 1 year, a follow-up study was completed for 174 of them to observe the long-term efficacy of SSRIs. The optimal-scaling regression analysis was used for testing the relationship between the different genotypes of five SNPs and the efficacy in MDD. Results: It showed that the patients with rs5443TT and rs2230739GG have a relatively good efficacy in response to short-term SSRIs. We also found that good efficacy appeared in depressed patients with rs2230739GG in response to long-term SSRIs. Conclusions: It suggested that different genotypes of rs5443 and rs2230739 might influence the signal transduction pathways of second message and affect therapeutic efficacy. PMID:22480177

  11. Activation of serotonin2A receptors in the medial septum-diagonal band of Broca complex enhanced working memory in the hemiparkinsonian rats.

    PubMed

    Li, Li-Bo; Zhang, Li; Sun, Yi-Na; Han, Ling-Na; Wu, Zhong-Heng; Zhang, Qiao-Jun; Liu, Jian

    2015-04-01

    Serotonin2A (5-HT2A) receptors are highly expressed in the medial septum-diagonal band of Broca complex (MS-DB), especially in parvalbumin (PV)-positive neurons linked to hippocampal theta rhythm, which is involved in cognition. Cognitive impairments commonly occur in Parkinson's disease. Here we performed behavioral, electrophysiological, neurochemical and immunohistochemical studies in rats with complete unilateral 6-hydroxydopamine lesions of the medial forebrain bundle (MFB) to assess the importance of dopamine (DA) depletion and MS-DB 5-HT2A receptors for working memory. The MFB lesions resulted in working memory impairment and decreases in firing rate and density of MS-DB PV-positive neurons, peak frequency of hippocampal theta rhythm, and DA levels in septohippocampal system and medial prefrontal cortex (mPFC) compared to control rats. Intra-MS-DB injection of high affinity 5-HT2A receptor agonist TCB-2 enhanced working memory, increased firing rate of PV-positive neurons and peak frequency of hippocampal theta rhythm, elevated DA levels in the hippocampus and mPFC, and decreased 5-HT level in the hippocampus in control and lesioned rats. Compared to control rats, the duration of the excitatory effect produced by TCB-2 on the firing rate of PV-positive neurons was markedly shortened in lesioned rats, indicating dysfunction of 5-HT2A receptors. These findings suggest that unilateral lesions of the MFB in rats induced working memory deficit, and activation of MS-DB 5-HT2A receptors enhanced working memory, which may be due to changes in the activity of septohippocampal network and monoamine levels in the hippocampus and mPFC. PMID:25486618

  12. Activation of serotonin2A receptors in the medial septum-diagonal band of Broca complex enhanced working memory in the hemiparkinsonian rats.

    PubMed

    Li, Li-Bo; Zhang, Li; Sun, Yi-Na; Han, Ling-Na; Wu, Zhong-Heng; Zhang, Qiao-Jun; Liu, Jian

    2015-04-01

    Serotonin2A (5-HT2A) receptors are highly expressed in the medial septum-diagonal band of Broca complex (MS-DB), especially in parvalbumin (PV)-positive neurons linked to hippocampal theta rhythm, which is involved in cognition. Cognitive impairments commonly occur in Parkinson's disease. Here we performed behavioral, electrophysiological, neurochemical and immunohistochemical studies in rats with complete unilateral 6-hydroxydopamine lesions of the medial forebrain bundle (MFB) to assess the importance of dopamine (DA) depletion and MS-DB 5-HT2A receptors for working memory. The MFB lesions resulted in working memory impairment and decreases in firing rate and density of MS-DB PV-positive neurons, peak frequency of hippocampal theta rhythm, and DA levels in septohippocampal system and medial prefrontal cortex (mPFC) compared to control rats. Intra-MS-DB injection of high affinity 5-HT2A receptor agonist TCB-2 enhanced working memory, increased firing rate of PV-positive neurons and peak frequency of hippocampal theta rhythm, elevated DA levels in the hippocampus and mPFC, and decreased 5-HT level in the hippocampus in control and lesioned rats. Compared to control rats, the duration of the excitatory effect produced by TCB-2 on the firing rate of PV-positive neurons was markedly shortened in lesioned rats, indicating dysfunction of 5-HT2A receptors. These findings suggest that unilateral lesions of the MFB in rats induced working memory deficit, and activation of MS-DB 5-HT2A receptors enhanced working memory, which may be due to changes in the activity of septohippocampal network and monoamine levels in the hippocampus and mPFC.

  13. Inhibition of alpha oscillations through serotonin-2A receptor activation underlies the visual effects of ayahuasca in humans.

    PubMed

    Valle, Marta; Maqueda, Ana Elda; Rabella, Mireia; Rodríguez-Pujadas, Aina; Antonijoan, Rosa Maria; Romero, Sergio; Alonso, Joan Francesc; Mañanas, Miquel Àngel; Barker, Steven; Friedlander, Pablo; Feilding, Amanda; Riba, Jordi

    2016-07-01

    Ayahuasca is an Amazonian psychotropic plant tea typically obtained from two plants, Banisteriopsis caapi and Psychotria viridis. It contains the psychedelic 5-HT2A and sigma-1 agonist N,N-dimethyltryptamine (DMT) plus β-carboline alkaloids with monoamine-oxidase (MAO)-inhibiting properties. Although the psychoactive effects of ayahuasca have commonly been attributed solely to agonism at the 5-HT2A receptor, the molecular target of classical psychedelics, this has not been tested experimentally. Here we wished to study the contribution of the 5-HT2A receptor to the neurophysiological and psychological effects of ayahuasca in humans. We measured drug-induced changes in spontaneous brain oscillations and subjective effects in a double-blind randomized placebo-controlled study involving the oral administration of ayahuasca (0.75mg DMT/kg body weight) and the 5-HT2A antagonist ketanserin (40mg). Twelve healthy, experienced psychedelic users (5 females) participated in four experimental sessions in which they received the following drug combinations: placebo+placebo, placebo+ayahuasca, ketanserin+placebo and ketanserin+ayahuasca. Ayahuasca induced EEG power decreases in the delta, theta and alpha frequency bands. Current density in alpha-band oscillations in parietal and occipital cortex was inversely correlated with the intensity of visual imagery induced by ayahuasca. Pretreatment with ketanserin inhibited neurophysiological modifications, reduced the correlation between alpha and visual effects, and attenuated the intensity of the subjective experience. These findings suggest that despite the chemical complexity of ayahuasca, 5-HT2A activation plays a key role in the neurophysiological and visual effects of ayahuasca in humans. PMID:27039035

  14. Inhibition of alpha oscillations through serotonin-2A receptor activation underlies the visual effects of ayahuasca in humans.

    PubMed

    Valle, Marta; Maqueda, Ana Elda; Rabella, Mireia; Rodríguez-Pujadas, Aina; Antonijoan, Rosa Maria; Romero, Sergio; Alonso, Joan Francesc; Mañanas, Miquel Àngel; Barker, Steven; Friedlander, Pablo; Feilding, Amanda; Riba, Jordi

    2016-07-01

    Ayahuasca is an Amazonian psychotropic plant tea typically obtained from two plants, Banisteriopsis caapi and Psychotria viridis. It contains the psychedelic 5-HT2A and sigma-1 agonist N,N-dimethyltryptamine (DMT) plus β-carboline alkaloids with monoamine-oxidase (MAO)-inhibiting properties. Although the psychoactive effects of ayahuasca have commonly been attributed solely to agonism at the 5-HT2A receptor, the molecular target of classical psychedelics, this has not been tested experimentally. Here we wished to study the contribution of the 5-HT2A receptor to the neurophysiological and psychological effects of ayahuasca in humans. We measured drug-induced changes in spontaneous brain oscillations and subjective effects in a double-blind randomized placebo-controlled study involving the oral administration of ayahuasca (0.75mg DMT/kg body weight) and the 5-HT2A antagonist ketanserin (40mg). Twelve healthy, experienced psychedelic users (5 females) participated in four experimental sessions in which they received the following drug combinations: placebo+placebo, placebo+ayahuasca, ketanserin+placebo and ketanserin+ayahuasca. Ayahuasca induced EEG power decreases in the delta, theta and alpha frequency bands. Current density in alpha-band oscillations in parietal and occipital cortex was inversely correlated with the intensity of visual imagery induced by ayahuasca. Pretreatment with ketanserin inhibited neurophysiological modifications, reduced the correlation between alpha and visual effects, and attenuated the intensity of the subjective experience. These findings suggest that despite the chemical complexity of ayahuasca, 5-HT2A activation plays a key role in the neurophysiological and visual effects of ayahuasca in humans.

  15. Brain structures implicated in the four-plate test in naïve and experienced Swiss mice using injection of diazepam and the 5-HT2A agonist DOI.

    PubMed

    Petit-Demoulière, Benoit; Massé, Fabienne; Cogrel, Nicolas; Hascoët, Martine; Bourin, Michel

    2009-12-01

    Four-plate test-retest (FPT-R) is a useful tool to study aversive memory and abolishment of benzodiazepine effects in experienced mice to four-plate test (FPT), namely one-trial tolerance. In the present study, we have used local injections paradigm, in order to localize structures implied in anxiolytic-like effects of two drugs in naïve and experienced mice: a benzodiazepine, diazepam that is only active in naïve mice; and a 5-HT(2A/2C) agonist, DOI that exert its anxiolytic-like effect both in naïve and experienced mice. Periacqueductal grey substance, three sub-regions of hippocampus (CA1, CA2 and CA3) and two nuclei of amygdala (BLA and LA) have been studied. Local injections did not cause any modifications of ambulatory activity. DOI injections elicit anxiolytic-like effects only when injected into CA2, in naïve and experienced mice. Diazepam had an anxiolytic-like effect in naïve mice, only when injected into lateral nucleus of amygdala; and in experienced mice when injected into PAG. These results help us to better understand the way of action of these two compounds and the structures functionally involved in their effects and in one-trial tolerance (OTT).

  16. 5-Hydroxytryptamine 2A receptor signaling cascade modulates adiponectin and plasminogen activator inhibitor 1 expression in adipose tissue.

    PubMed

    Uchida-Kitajima, Shoko; Yamauchi, Toshimasa; Takashina, Youko; Okada-Iwabu, Miki; Iwabu, Masato; Ueki, Kohjiro; Kadowaki, Takashi

    2008-09-01

    Knowledge of the regulatory factors associated with down-regulation of adiponectin gene expression and up-regulation of PAI-1 gene expression is crucial to understand the pathophysiological basis of obesity and metabolic diseases, and could establish new treatment strategies for these conditions. We showed that expression of 5-HT(2A) receptors was up-regulated in hypertrophic 3T3-L1 adipocytes, which exhibited decreased expression of adiponectin and increased expression of PAI-1. 5-HT(2A) receptor antagonists and suppression of 5-HT(2A) receptor gene expression enhanced adiponectin expression. Activation of Gq negatively regulated adiponectin expression, and inhibition of mitogen-activated protein kinase reversed the Gq-induced effect. Moreover, the 5-HT(2A) receptor blockade reduced PAI-1 expression. These findings indicate that antagonism of 5-HT(2A) receptors in adipocytes could improve the obesity-linked decreases in adiponectin expression and increases in PAI-1 expression.

  17. Regulation of rat cortical 5-hydroxytryptamine2A-receptor mediated electrophysiological responses by repeated daily treatment with electroconvulsive shock or imipramine

    PubMed Central

    Marek, Gerard J.

    2008-01-01

    Down-regulation of 5-hydroxytryptamine2A (5-HT2A) receptors has been a consistent effect induced by most antidepressant drugs. In contrast, electroconvulsive shock (ECS) up-regulates the number of 5-HT2A receptor binding sites. However, the effects of antidepressants on 5-HT2A receptor-mediated responses on identified cells of the cerebral cortex has not been examined. The purpose of the present study was to compare the effects of the tricyclic antidepressant imipramine and ECS on 5-HT2A receptor-mediated electrophysiological responses involving glutamatergic and GABAergic neurotransmission in the rat medial prefrontal cortex (mPFC) and piriform cortex, respectively. The electrophysiological effects of activating 5-HT2A receptors was consistent with 5-HT2A receptor binding regulation for imipramine and ECS except for the mPFC where chronic ECS decreased the potency of 5-HT at a 5-HT2A receptor-mediated response. These findings are consistent with the general hypothesis that chronic antidepressant treatments shift the balance of serotonergic neurotransmission towards inhibitory effects in the cortex. PMID:18294819

  18. Regulation of rat cortical 5-hydroxytryptamine2A receptor-mediated electrophysiological responses by repeated daily treatment with electroconvulsive shock or imipramine.

    PubMed

    Marek, Gerard J

    2008-07-01

    Down-regulation of 5-hydroxytryptamine(2A) (5-HT(2A)) receptors has been a consistent effect induced by most antidepressant drugs. In contrast, electroconvulsive shock (ECS) up-regulates the number of 5-HT(2A) receptor binding sites. However, the effects of antidepressants on 5-HT(2A) receptor-mediated responses on identified cells of the cerebral cortex have not been examined. The purpose of the present study was to compare the effects of the tricyclic antidepressant imipramine and ECS on 5-HT(2A) receptor-mediated electrophysiological responses involving glutamatergic and GABAergic neurotransmission in the rat medial prefrontal cortex (mPFC) and piriform cortex, respectively. The electrophysiological effects of activating 5-HT(2A) receptors were consistent with 5-HT(2A) receptor binding regulation for imipramine and ECS except for the mPFC where chronic ECS decreased the potency of 5-HT at a 5-HT(2A) receptor-mediated response. These findings are consistent with the general hypothesis that chronic antidepressant treatments shift the balance of serotonergic neurotransmission towards inhibitory effects in the cortex.

  19. 5-Hydroxytryptamine2A serotonin receptors in the primate cerebral cortex: possible site of action of hallucinogenic and antipsychotic drugs in pyramidal cell apical dendrites.

    PubMed

    Jakab, R L; Goldman-Rakic, P S

    1998-01-20

    To identify the cortical sites where 5-hydroxytryptamine2A (5-HT2A) serotonin receptors respond to the action of hallucinogens and atypical antipsychotic drugs, we have examined the cellular and subcellular distribution of these receptors in the cerebral cortex of macaque monkeys (with a focus on prefrontal areas) by using light and electron microscopic immunocytochemical techniques. 5-HT2A receptor immunoreactivity was detected in all cortical layers, among which layers II and III and layers V and VI were intensely stained, and layer IV was weakly labeled. The majority of the receptor-labeled cells were pyramidal neurons and the most intense immunolabeling was consistently confined to their parallelly aligned proximal apical dendrites that formed two intensely stained bands above and below layer IV. In double-label experiments, 5-HT2A label was found in calbindin D28k-positive, nonphosphorylated-neurofilament-positive, and immuno-negative pyramidal cells, suggesting that probably all pyramidal cells express 5-HT2A receptors. 5-HT2A label was also found in large- and medium-size interneurons, some of which were immuno-positive for calbindin. 5-HT2A receptor label was also associated with axon terminals. These findings reconcile the data on the receptor's cortical physiology and localization by (i) establishing that 5-HT2A receptors are located postsynaptically and presynaptically, (ii) demonstrating that pyramidal neurons constitute the major 5-HT2A-receptor-expressing cells in the cortex, and (iii) supporting the view that the apical dendritic field proximal to the pyramidal cell soma is the "hot spot" for 5-HT2A-receptor-mediated physiological actions relevant to normal and "psychotic" functional states of the cerebral cortex.

  20. Serotonin 2a Receptor and Serotonin 1a Receptor Interact Within the Medial Prefrontal Cortex During Recognition Memory in Mice

    PubMed Central

    Morici, Juan F.; Ciccia, Lucia; Malleret, Gaël; Gingrich, Jay A.; Bekinschtein, Pedro; Weisstaub, Noelia V.

    2015-01-01

    Episodic memory, can be defined as the memory for unique events. The serotonergic system one of the main neuromodulatory systems in the brain appears to play a role in it. The serotonin 2a receptor (5-HT2aR) one of the principal post-synaptic receptors for 5-HT in the brain, is involved in neuropsychiatric and neurological disorders associated with memory deficits. Recognition memory can be defined as the ability to recognize if a particular event or item was previously encountered and is thus considered, under certain conditions, a form of episodic memory. As human data suggest that a constitutively decrease of 5-HT2A signaling might affect episodic memory performance we decided to compare the performance of mice with disrupted 5-HT2aR signaling (htr2a−/−) with wild type (htr2a+/+) littermates in different recognition memory and working memory tasks that differed in the level of proactive interference. We found that ablation of 5-HT2aR signaling throughout development produces a deficit in tasks that cannot be solved by single item strategy suggesting that 5-HT2aR signaling is involved in interference resolution. We also found that in the absence of 5-HT2aR signaling serotonin has a deleterious effect on recognition memory retrieval through the activation of 5-HT1aR in the medial prefrontal cortex. PMID:26779016

  1. Serotonin 2a Receptor and Serotonin 1a Receptor Interact Within the Medial Prefrontal Cortex During Recognition Memory in Mice.

    PubMed

    Morici, Juan F; Ciccia, Lucia; Malleret, Gaël; Gingrich, Jay A; Bekinschtein, Pedro; Weisstaub, Noelia V

    2015-01-01

    Episodic memory, can be defined as the memory for unique events. The serotonergic system one of the main neuromodulatory systems in the brain appears to play a role in it. The serotonin 2a receptor (5-HT2aR) one of the principal post-synaptic receptors for 5-HT in the brain, is involved in neuropsychiatric and neurological disorders associated with memory deficits. Recognition memory can be defined as the ability to recognize if a particular event or item was previously encountered and is thus considered, under certain conditions, a form of episodic memory. As human data suggest that a constitutively decrease of 5-HT2A signaling might affect episodic memory performance we decided to compare the performance of mice with disrupted 5-HT2aR signaling (htr2a (-/-)) with wild type (htr2a (+/+)) littermates in different recognition memory and working memory tasks that differed in the level of proactive interference. We found that ablation of 5-HT2aR signaling throughout development produces a deficit in tasks that cannot be solved by single item strategy suggesting that 5-HT2aR signaling is involved in interference resolution. We also found that in the absence of 5-HT2aR signaling serotonin has a deleterious effect on recognition memory retrieval through the activation of 5-HT1aR in the medial prefrontal cortex. PMID:26779016

  2. Up-regulation of 5-HT2B receptor density and receptor-mediated glycogenolysis in mouse astrocytes by long-term fluoxetine administration.

    PubMed

    Kong, Ebenezer K C; Peng, Liang; Chen, Ye; Yu, Albert C H; Hertz, Leif

    2002-02-01

    The effects were studied of short-term (1 week) versus long-term (2-3 weeks) fluoxetine treatment of primary cultures of mouse astrocytes, differentiated by treatment with dibutyryl cyclic AMP. From previous experiments it is known that acute treatment with fluoxetine stimulates glycogenolysis and increases free cytosolic Ca2+ concentration ([Ca2+]i]) in these cultures, whereas short-term (one week) treatment with 10 microM down-regulates the effects on glycogen and [Ca2+]i, when fluoxetine administration is renewed (or when serotonin is administered). Moreover, antagonist studies have shown that these responses are evoked by activation of a 5-HT2, receptor that is different from the 5-HT2A receptor and therefore at that time tentatively were interpreted as being exerted on 5-HT2C receptors. In the present study the cultures were found by RT-PCR to express mRNA for 5-HT2A and 5-HT2B receptors, but not for the 5-HT2C receptor, identifying the 5-HT2 receptor activated by fluoxetine as the 5-HT2B receptor, the most recently cloned 5-Ht2 receptor and a 5-HT receptor known to be more abundant in human, than in rodent, brain. Both short-term and long-term treatment with fluoxetine increased the specific binding of [3H]mesulergine, a ligand for alL three 5-HT2 receptors. Long-term treatment with fluoxetine caused an agonist-induced up-regulation of the glycogenolytic response to renewed administration of fluoxetine, whereas short-term treatment abolished the fluoxetine-induced hydrolysis of glycogen. Thus, during a treatment period similar to that required for fluoxetine's clinical response to occur, 5-HT2B-mediated effects are initially down-regulated and subsequently up-regulated. PMID:11930908

  3. Behavioral tolerance to lysergic acid diethylamide is associated with reduced serotonin-2A receptor signaling in rat cortex.

    PubMed

    Gresch, Paul J; Smith, Randy L; Barrett, Robert J; Sanders-Bush, Elaine

    2005-09-01

    Tolerance is defined as a decrease in responsiveness to a drug after repeated administration. Tolerance to the behavioral effects of hallucinogens occurs in humans and animals. In this study, we used drug discrimination to establish a behavioral model of lysergic acid diethylamide (LSD) tolerance and examined whether tolerance to the stimulus properties of LSD is related to altered serotonin receptor signaling. Rats were trained to discriminate 60 microg/kg LSD from saline in a two-lever drug discrimination paradigm. Two groups of animals were assigned to either chronic saline treatment or chronic LSD treatment. For chronic treatment, rats from each group were injected once per day with either 130 microg/kg LSD or saline for 5 days. Rats were tested for their ability to discriminate either saline or 60 microg/kg LSD, 24 h after the last chronic injection. Rats receiving chronic LSD showed a 44% reduction in LSD lever selection, while rats receiving chronic vehicle showed no change in percent choice on the LSD lever. In another group of rats receiving the identical chronic LSD treatment, LSD-stimulated [35S]GTPgammaS binding, an index of G-protein coupling, was measured in the rat brain by autoradiography. After chronic LSD, a significant reduction in LSD-stimulated [35S]GTPgammaS binding was observed in the medial prefrontal cortex and anterior cingulate cortex. Furthermore, chronic LSD produced a significant reduction in 2,5-dimethoxy-4-iodoamphetamine-stimulated [35S]GTPgammaS binding in medial prefrontal cortex and anterior cingulate cortex, which was blocked by MDL 100907, a selective 5-HT2A receptor antagonist, but not SB206553, a 5-HT2C receptor antagonist, indicating a reduction in 5-HT2A receptor signaling. 125I-LSD binding to 5-HT2A receptors was reduced in cortical regions, demonstrating a reduction in 5-HT2A receptor density. Taken together, these results indicate that adaptive changes in LSD-stimulated serotonin receptor signaling may mediate tolerance

  4. Dynamic alterations of serotonergic metabolism and receptors during social isolation of low- and high-active mice.

    PubMed

    Rilke, O; Freier, D; Jähkel, M; Oehler, J

    1998-04-01

    Alterations induced by social isolation (1 day to 18 weeks) in low- and high-active mice (LAM and HAM) were studied in respect to serotonin metabolism, [3H]-8-OH-DPAT binding of presynaptic (midbrain), postsynaptic (hippocampus) 5-HT1A receptors and [3H]-ketanserin binding of cortical 5-HT2A receptors. Individual housing of mice was associated with reduction of serotonin metabolism, depending on isolation time and brain structure. Whereas a transient decrease in the striatum and cortex was detected between 1 week and 6 weeks, reduction of cerebellar and hippocampal serotonin metabolism was found later (12-18 weeks). Serotonergic systems of HAM were found to be more reactive to environmental disturbances, and their serotonin metabolism was more affected by social isolation. Isolation-induced upregulation of cortical 5-HT2A receptors was measured only in HAM. Densities of postsynaptic 5-HT1A receptors in the hippocampus did differ either in grouped or isolated mice. However, there were significant differences in hippocampal 5-HT1A receptor affinity, especially between 1 day and 3 weeks. Transient downregulation of presynaptic 5-HT1A receptors in the midbrain was found in isolated mice between 3 and 6 weeks. These results are discussed in terms of interactions between serotonergic alterations and isolation-induced aggression.

  5. Quantitative phosphoproteomics unravels biased phosphorylation of serotonin 2A receptor at Ser280 by hallucinogenic versus nonhallucinogenic agonists.

    PubMed

    Karaki, Samah; Becamel, Carine; Murat, Samy; Mannoury la Cour, Clotilde; Millan, Mark J; Prézeau, Laurent; Bockaert, Joël; Marin, Philippe; Vandermoere, Franck

    2014-05-01

    The serotonin 5-HT(2A) receptor is a primary target of psychedelic hallucinogens such as lysergic acid diethylamine, mescaline, and psilocybin, which reproduce some of the core symptoms of schizophrenia. An incompletely resolved paradox is that only some 5-HT(2A) receptor agonists exhibit hallucinogenic activity, whereas structurally related agonists with comparable affinity and activity lack such a psychoactive activity. Using a strategy combining stable isotope labeling by amino acids in cell culture with enrichment in phosphorylated peptides by means of hydrophilic interaction liquid chromatography followed by immobilized metal affinity chromatography, we compared the phosphoproteome in HEK-293 cells transiently expressing the 5-HT(2A) receptor and exposed to either vehicle or the synthetic hallucinogen 1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane (DOI) or the nonhallucinogenic 5-HT(2A) agonist lisuride. Among the 5995 identified phosphorylated peptides, 16 sites were differentially phosphorylated upon exposure of cells to DOI versus lisuride. These include a serine (Ser(280)) located in the third intracellular loop of the 5-HT(2A) receptor, a region important for its desensitization. The specific phosphorylation of Ser(280) by hallucinogens was further validated by quantitative mass spectrometry analysis of immunopurified receptor digests and by Western blotting using a phosphosite specific antibody. The administration of DOI, but not of lisuride, to mice, enhanced the phosphorylation of 5-HT(2A) receptors at Ser(280) in the prefrontal cortex. Moreover, hallucinogens induced a less pronounced desensitization of receptor-operated signaling in HEK-293 cells and neurons than did nonhallucinogenic agonists. The mutation of Ser(280) to aspartic acid (to mimic phosphorylation) reduced receptor desensitization by nonhallucinogenic agonists, whereas its mutation to alanine increased the ability of hallucinogens to desensitize the receptor. This study reveals a biased

  6. Quantitative Phosphoproteomics Unravels Biased Phosphorylation of Serotonin 2A Receptor at Ser280 by Hallucinogenic versus Nonhallucinogenic Agonists*

    PubMed Central

    Karaki, Samah; Becamel, Carine; Murat, Samy; Mannoury la Cour, Clotilde; Millan, Mark J.; Prézeau, Laurent; Bockaert, Joël; Marin, Philippe; Vandermoere, Franck

    2014-01-01

    The serotonin 5-HT2A receptor is a primary target of psychedelic hallucinogens such as lysergic acid diethylamine, mescaline, and psilocybin, which reproduce some of the core symptoms of schizophrenia. An incompletely resolved paradox is that only some 5-HT2A receptor agonists exhibit hallucinogenic activity, whereas structurally related agonists with comparable affinity and activity lack such a psychoactive activity. Using a strategy combining stable isotope labeling by amino acids in cell culture with enrichment in phosphorylated peptides by means of hydrophilic interaction liquid chromatography followed by immobilized metal affinity chromatography, we compared the phosphoproteome in HEK-293 cells transiently expressing the 5-HT2A receptor and exposed to either vehicle or the synthetic hallucinogen 1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane (DOI) or the nonhallucinogenic 5-HT2A agonist lisuride. Among the 5995 identified phosphorylated peptides, 16 sites were differentially phosphorylated upon exposure of cells to DOI versus lisuride. These include a serine (Ser280) located in the third intracellular loop of the 5-HT2A receptor, a region important for its desensitization. The specific phosphorylation of Ser280 by hallucinogens was further validated by quantitative mass spectrometry analysis of immunopurified receptor digests and by Western blotting using a phosphosite specific antibody. The administration of DOI, but not of lisuride, to mice, enhanced the phosphorylation of 5-HT2A receptors at Ser280 in the prefrontal cortex. Moreover, hallucinogens induced a less pronounced desensitization of receptor-operated signaling in HEK-293 cells and neurons than did nonhallucinogenic agonists. The mutation of Ser280 to aspartic acid (to mimic phosphorylation) reduced receptor desensitization by nonhallucinogenic agonists, whereas its mutation to alanine increased the ability of hallucinogens to desensitize the receptor. This study reveals a biased phosphorylation of

  7. Lysergic acid diethylamide-induced Fos expression in rat brain: role of serotonin-2A receptors.

    PubMed

    Gresch, P J; Strickland, L V; Sanders-Bush, E

    2002-01-01

    Lysergic acid diethylamide (LSD) produces altered mood and hallucinations in humans and binds with high affinity to serotonin-2A (5-HT(2A)) receptors. Although LSD interacts with other receptors, the activation of 5-HT(2A) receptors is thought to mediate the hallucinogenic properties of LSD. The goal of this study was to identify the brain sites activated by LSD and to determine the influence of 5-HT(2A) receptors in this activation. Rats were pretreated with the 5-HT(2A) receptor antagonist MDL 100907 (0.3 mg/kg, i.p.) or vehicle 30 min prior to LSD (500 microg/kg, i.p.) administration and killed 3 h later. Brain tissue was examined for Fos protein expression by immunohistochemistry. LSD administration produced a five- to eight-fold increase in Fos-like immunoreactivity in medial prefrontal cortex, anterior cingulate cortex, and central nucleus of amygdala. However, in dorsal striatum and nucleus accumbens no increase in Fos-like immunoreactivity was observed. Pretreatment with MDL 100907 completely blocked LSD-induced Fos-like immunoreactivity in medial prefrontal cortex and anterior cingulate cortex, but only partially blocked LSD-induced Fos-like immunoreactivity in amygdala. Double-labeled immunohistochemistry revealed that LSD did not induce Fos-like immunoreactivity in cortical cells expressing 5-HT(2A) receptors, suggesting an indirect activation of cortical neurons. These results indicate that the LSD activation of medial prefrontal cortex and anterior cingulate cortex is mediated by 5-HT(2A) receptors, whereas in amygdala 5-HT(2A) receptor activation is a component of the response. These findings support the hypothesis that the medial prefrontal cortex, anterior cingulate cortex, and perhaps the amygdala, are important regions involved in the production of hallucinations.

  8. Increased numbers of motor activity peaks during light cycle are associated with reductions in adrenergic alpha(2)-receptor levels in a transgenic Huntington's disease rat model.

    PubMed

    Bode, Felix J; Stephan, Michael; Wiehager, Sara; Nguyen, Huu Phuc; Björkqvist, Maria; von Hörsten, Stephan; Bauer, Andreas; Petersén, Asa

    2009-12-14

    Huntington's disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in the HD gene. Besides psychiatric, motor and cognitive symptoms, HD patients suffer from sleep disturbances. In order to screen a rat model transgenic for HD (tgHD rats) for sleep-wake cycle dysregulation, we monitored their circadian activity peaks in the present study. TgHD rats of both sexes showed hyperactivity during the dark cycle and more frequent light cycle activity peaks indicative for a disturbed sleep-wake cycle. Focusing on males at the age of 4 and 14 months, analyses of receptor levels in the hypothalamus and the basal forebrain revealed that 5-HT(2A)- and adrenergic alpha(2)-receptor densities in these regions were significantly altered in tgHD rats compared to their wild-type littermates. Adrenergic receptor densities correlated negatively with the light cycle hyperactivity peaks at later stages of the disease in male tgHD rats. Furthermore, reduced leptin levels, a feature associated with circadian misalignment, were present. Our study demonstrates that the male tgHD rat is a suitable model to investigate HD associated sleep alterations. Further studies are warranted to elucidate the role of adrenergic- and 5-HT(2A)-receptors as therapeutic targets for dysregulation of the circadian activity in HD.

  9. Presynaptic serotonin 2A receptors modulate thalamocortical plasticity and associative learning

    PubMed Central

    Barre, Alexander; Berthoux, Coralie; De Bundel, Dimitri; Valjent, Emmanuel; Bockaert, Joël; Marin, Philippe; Bécamel, Carine

    2016-01-01

    Higher-level cognitive processes strongly depend on a complex interplay between mediodorsal thalamus nuclei and the prefrontal cortex (PFC). Alteration of thalamofrontal connectivity has been involved in cognitive deficits of schizophrenia. Prefrontal serotonin (5-HT)2A receptors play an essential role in cortical network activity, but the mechanism underlying their modulation of glutamatergic transmission and plasticity at thalamocortical synapses remains largely unexplored. Here, we show that 5-HT2A receptor activation enhances NMDA transmission and gates the induction of temporal-dependent plasticity mediated by NMDA receptors at thalamocortical synapses in acute PFC slices. Expressing 5-HT2A receptors in the mediodorsal thalamus (presynaptic site) of 5-HT2A receptor-deficient mice, but not in the PFC (postsynaptic site), using a viral gene-delivery approach, rescued the otherwise absent potentiation of NMDA transmission, induction of temporal plasticity, and deficit in associative memory. These results provide, to our knowledge, the first physiological evidence of a role of presynaptic 5-HT2A receptors located at thalamocortical synapses in the control of thalamofrontal connectivity and the associated cognitive functions. PMID:26903620

  10. On the role of 5-HT(1A) receptor gene in behavioral effect of brain-derived neurotrophic factor.

    PubMed

    Naumenko, Vladimir S; Kondaurova, Elena M; Bazovkina, Daria V; Tsybko, Anton S; Il'chibaeva, Tatyana V; Popova, Nina K

    2014-08-01

    Experiments were made on a congenic AKR.CBA-D13Mit76C (76C) mouse strain created by transferring a chromosome 13 fragment containing the 5-HT1A receptor gene from a CBA strain to an AKR background. It was shown that 76C mice differed from AKR mice by decreased 5-HT1A receptor and tryptophan hydroxylase-2 (tph-2) genes expression in the midbrain. Functional activity of 5-HT2A receptors and 5-HT(2A) receptor mRNA levels in the midbrain and hippocampus of 76C mice were decreased compared with AKR mice. Central brain-derived neurotrophic factor (BDNF) administration (300 ng i.c.v.) reduced 5-HT1A and 5-HT(2A) receptor mRNA levels in the frontal cortex and tph-2 mRNA level in the midbrain of AKR mice. However, BDNF failed to produce any effect on the expression of 5-HT(1A) , 5-HT(2A) , and tph-2 genes in 76C mice but decreased functional activity of 5-HT(2A) receptors in 76C mice and increased it in AKR mice. BDNF restored social deficiency in 76C mice but produced asocial behavior (aggressive attacks towards young mice) in AKR mice. The data indicate that a small genetic variation altered the response to BDNF and show an important role of 5-HT(1A) receptor gene in the 5-HT system response to BDNF treatment and in behavioral effects of BDNF.

  11. Behavioral evidence for interactions between a hallucinogenic drug and group II metabotropic glutamate receptors.

    PubMed

    Gewirtz, J C; Marek, G J

    2000-11-01

    Recent electrophysiological studies in our laboratory have demonstrated a physiological interaction between 5-HT(2A) and metabotropic glutamate2/3 (mGlu2/3) receptors in the medial prefrontal cortex. Several behavioral studies have found that phenethylamine hallucinogens with partial agonist activity at 5-HT(2A) receptors induce head shakes when directly administered into the medial prefrontal cortex. The purpose of the present experiments was to examine whether an interaction occurs between mGlu2/3 and 5-HT(2A) receptors on a behavioral level using head shakes induced by phenethylamine hallucinogens as a model of 5-HT(2A) receptor activation. Administration of the mGlu2/3 agonist LY354740 (0.3-10 mg/kg, ip) suppressed head shakes induced by the phenethylamine hallucinogen 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). Conversely, administration of the mGlu2/3 antagonist LY341495 (1 mg/kg, ip) enhanced the frequency of DOI-induced head shakes. Taken together, these results raise the possibility that the psychomimetic properties of hallucinogenic drugs may be mediated in part, via increased glutamate release following activation of 5-HT(2A) receptors.

  12. Activation of serotonin 2A receptors underlies the psilocybin-induced effects on α oscillations, N170 visual-evoked potentials, and visual hallucinations.

    PubMed

    Kometer, Michael; Schmidt, André; Jäncke, Lutz; Vollenweider, Franz X

    2013-06-19

    Visual illusions and hallucinations are hallmarks of serotonergic hallucinogen-induced altered states of consciousness. Although the serotonergic hallucinogen psilocybin activates multiple serotonin (5-HT) receptors, recent evidence suggests that activation of 5-HT2A receptors may lead to the formation of visual hallucinations by increasing cortical excitability and altering visual-evoked cortical responses. To address this hypothesis, we assessed the effects of psilocybin (215 μg/kg vs placebo) on both α oscillations that regulate cortical excitability and early visual-evoked P1 and N170 potentials in healthy human subjects. To further disentangle the specific contributions of 5-HT2A receptors, subjects were additionally pretreated with the preferential 5-HT2A receptor antagonist ketanserin (50 mg vs placebo). We found that psilocybin strongly decreased prestimulus parieto-occipital α power values, thus precluding a subsequent stimulus-induced α power decrease. Furthermore, psilocybin strongly decreased N170 potentials associated with the appearance of visual perceptual alterations, including visual hallucinations. All of these effects were blocked by pretreatment with the 5-HT2A antagonist ketanserin, indicating that activation of 5-HT2A receptors by psilocybin profoundly modulates the neurophysiological and phenomenological indices of visual processing. Specifically, activation of 5-HT2A receptors may induce a processing mode in which stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation through the modulation of α oscillations. Furthermore, the observed reduction of N170 visual-evoked potentials may be a key mechanism underlying 5-HT2A receptor-mediated visual hallucinations. This change in N170 potentials may be important not only for psilocybin-induced states but also for understanding acute hallucinatory states seen in psychiatric disorders, such as schizophrenia and Parkinson's disease. PMID:23785166

  13. Activation of serotonin 2A receptors underlies the psilocybin-induced effects on α oscillations, N170 visual-evoked potentials, and visual hallucinations.

    PubMed

    Kometer, Michael; Schmidt, André; Jäncke, Lutz; Vollenweider, Franz X

    2013-06-19

    Visual illusions and hallucinations are hallmarks of serotonergic hallucinogen-induced altered states of consciousness. Although the serotonergic hallucinogen psilocybin activates multiple serotonin (5-HT) receptors, recent evidence suggests that activation of 5-HT2A receptors may lead to the formation of visual hallucinations by increasing cortical excitability and altering visual-evoked cortical responses. To address this hypothesis, we assessed the effects of psilocybin (215 μg/kg vs placebo) on both α oscillations that regulate cortical excitability and early visual-evoked P1 and N170 potentials in healthy human subjects. To further disentangle the specific contributions of 5-HT2A receptors, subjects were additionally pretreated with the preferential 5-HT2A receptor antagonist ketanserin (50 mg vs placebo). We found that psilocybin strongly decreased prestimulus parieto-occipital α power values, thus precluding a subsequent stimulus-induced α power decrease. Furthermore, psilocybin strongly decreased N170 potentials associated with the appearance of visual perceptual alterations, including visual hallucinations. All of these effects were blocked by pretreatment with the 5-HT2A antagonist ketanserin, indicating that activation of 5-HT2A receptors by psilocybin profoundly modulates the neurophysiological and phenomenological indices of visual processing. Specifically, activation of 5-HT2A receptors may induce a processing mode in which stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation through the modulation of α oscillations. Furthermore, the observed reduction of N170 visual-evoked potentials may be a key mechanism underlying 5-HT2A receptor-mediated visual hallucinations. This change in N170 potentials may be important not only for psilocybin-induced states but also for understanding acute hallucinatory states seen in psychiatric disorders, such as schizophrenia and Parkinson's disease.

  14. G-protein Receptor Kinase 5 Regulates the Cannabinoid Receptor 2-induced Up-regulation of Serotonin 2A Receptors*

    PubMed Central

    Franklin, Jade M.; Carrasco, Gonzalo A.

    2013-01-01

    We have recently reported that cannabinoid agonists can up-regulate and enhance the activity of serotonin 2A (5-HT2A) receptors in the prefrontal cortex (PFCx). Increased expression and activity of cortical 5-HT2A receptors has been associated with neuropsychiatric disorders, such as anxiety and schizophrenia. Here we report that repeated CP55940 exposure selectively up-regulates GRK5 proteins in rat PFCx and in a neuronal cell culture model. We sought to examine the mechanism underlying the regulation of GRK5 and to identify the role of GRK5 in the cannabinoid agonist-induced up-regulation and enhanced activity of 5-HT2A receptors. Interestingly, we found that cannabinoid agonist-induced up-regulation of GRK5 involves CB2 receptors, β-arrestin 2, and ERK1/2 signaling because treatment with CB2 shRNA lentiviral particles, β-arrestin 2 shRNA lentiviral particles, or ERK1/2 inhibitor prevented the cannabinoid agonist-induced up-regulation of GRK5. Most importantly, we found that GRK5 shRNA lentiviral particle treatment prevented the cannabinoid agonist-induced up-regulation and enhanced 5-HT2A receptor-mediated calcium release. Repeated cannabinoid exposure was also associated with enhanced phosphorylation of CB2 receptors and increased interaction between β-arrestin 2 and ERK1/2. These latter phenomena were also significantly inhibited by GRK5 shRNA lentiviral treatment. Our results suggest that sustained activation of CB2 receptors, which up-regulates 5-HT2A receptor signaling, enhances GRK5 expression; the phosphorylation of CB2 receptors; and the β-arrestin 2/ERK interactions. These data could provide a rationale for some of the adverse effects associated with repeated cannabinoid agonist exposure. PMID:23592773

  15. 5-HT2 receptors mediate functional modulation of GABAa receptors and inhibitory synaptic transmissions in human iPS-derived neurons

    PubMed Central

    Wang, Haitao; Hu, Lingli; Liu, Chunhua; Su, Zhenghui; Wang, Lihui; Pan, Guangjin; Guo, Yiping; He, Jufang

    2016-01-01

    Neural progenitors differentiated from induced pluripotent stem cells (iPS) hold potentials for treating neurological diseases. Serotonin has potent effects on neuronal functions through multiple receptors, underlying a variety of neural disorders. Glutamate and GABA receptors have been proven functional in neurons differentiated from iPS, however, little is known about 5-HT receptor-mediated modulation in such neuronal networks. In the present study, human iPS were differentiated into cells possessing featured physiological properties of cortical neurons. Whole-cell patch-clamp recording was used to examine the involvement of 5-HT2 receptors in functional modulation of GABAergic synaptic transmission. We found that serotonin and DOI (a selective agonist of 5-HT2A/C receptor) reversibly reduced GABA-activated currents, and this 5-HT2A/C receptor mediated inhibition required G protein, PLC, PKC, and Ca2+ signaling. Serotonin increased the frequency of miniature inhibitory postsynaptic currents (mIPSCs), which could be mimicked by α-methylserotonin, a 5-HT2 receptor agonist. In contrast, DOI reduced both frequency and amplitude of mIPSCs. These findings suggested that in iPS-derived human neurons serotonin postsynaptically reduced GABAa receptor function through 5-HT2A/C receptors, but presynaptically other 5-HT2 receptors counteracted the action of 5-HT2A/C receptors. Functional expression of serotonin receptors in human iPS-derived neurons provides a pre-requisite for their normal behaviors after grafting. PMID:26837719

  16. Differential interactions of indolealkylamines with 5-hydroxytryptamine receptor subtypes.

    PubMed

    McKenna, D J; Repke, D B; Lo, L; Peroutka, S J

    1990-03-01

    Affinities of drugs for 21 indolealkylamine derivatives, some with putative hallucinogenic activity, were determined at 5-HT1A, 5-HT2A and 5-HT2B recognition sites, using radioligand competition studies. Nearly all of the derivatives displayed greatest potency for the 5-HT2A receptor, labelled by [125I]R-(-)DOI in the cortex of the rat. Most derivatives displayed 2-10 times lower affinity at the HT2B receptor labelled by [3H]ketanserin in bovine cortex. Derivatives lacking ring substituents displayed lower affinities for all of the recognition sites, compared to derivatives substituted in the 4- or 5-position of the indole ring. The 4-hydroxylated derivatives displayed 25-380-fold selectivity for the 5-HT2A site, vs the 5-HT1A site, while the 5-substituted derivatives displayed approximately equal potency at the 5-HT1A and 5-HT2A sites. Affinity of all the compounds at the 5-HT2B site was greater than 300 nM. The 6-substituted derivatives displayed greater than micromolar affinities for all of the 5-HT recognition sites examined. The size of the N,N-dialkyl substituent was a secondary determinant of affinity, with groups larger than N,N-diisopropyl resulting in a marked reduction in affinity at both the 5-HT2A and 5-HT1A recognition sites. This study demonstrated that hallucinogenic 4-hydroxy-indolealkylamines, like psychotomimetic phenylisopropylamines, bind potently and selectively to the 5-HT2A recognition site, labelled by [125I]R-(-)DOI. This provides further evidence indicating that this recently described subtype of the 5-HT2 receptor may partially mediate the action of hallucinogenic agents.

  17. Serotonin 2A receptor agonist binding in the human brain with [11C]Cimbi-36

    PubMed Central

    Ettrup, Anders; da Cunha-Bang, Sophie; McMahon, Brenda; Lehel, Szabolcs; Dyssegaard, Agnete; Skibsted, Anine W; Jørgensen, Louise M; Hansen, Martin; Baandrup, Anders O; Bache, Søren; Svarer, Claus; Kristensen, Jesper L; Gillings, Nic; Madsen, Jacob; Knudsen, Gitte M

    2014-01-01

    [11C]Cimbi-36 was recently developed as a selective serotonin 2A (5-HT2A) receptor agonist radioligand for positron emission tomography (PET) brain imaging. Such an agonist PET radioligand may provide a novel, and more functional, measure of the serotonergic system and agonist binding is more likely than antagonist binding to reflect 5-HT levels in vivo. Here, we show data from a first-in-human clinical trial with [11C]Cimbi-36. In 29 healthy volunteers, we found high brain uptake and distribution according to 5-HT2A receptors with [11C]Cimbi-36 PET. The two-tissue compartment model using arterial input measurements provided the most optimal quantification of cerebral [11C]Cimbi-36 binding. Reference tissue modeling was feasible as it induced a negative but predictable bias in [11C]Cimbi-36 PET outcome measures. In five subjects, pretreatment with the 5-HT2A receptor antagonist ketanserin before a second PET scan significantly decreased [11C]Cimbi-36 binding in all cortical regions with no effects in cerebellum. These results confirm that [11C]Cimbi-36 binding is selective for 5-HT2A receptors in the cerebral cortex and that cerebellum is an appropriate reference tissue for quantification of 5-HT2A receptors in the human brain. Thus, we here describe [11C]Cimbi-36 as the first agonist PET radioligand to successfully image and quantify 5-HT2A receptors in the human brain. PMID:24780897

  18. Phosphoinositide system-linked serotonin receptor subtypes and their pharmacological properties and clinical correlates.

    PubMed Central

    Pandey, S C; Davis, J M; Pandey, G N

    1995-01-01

    Serotonergic neurotransmission represents a complex mechanism involving pre- and post-synaptic events and distinct 5-HT receptor subtypes. Serotonin (5-HT) receptors have been classified into several categories, and they are termed as 5-HT1, 5-HT2, 5-HT3, 5-HT4, 5-HT5, 5-HT6 and 5-HT7 type receptors. 5-HT1 receptors have been further subdivided into 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E and 5-HT1F. 5-HT2 receptors have been divided into 5-HT2A, 5-HT2B and 5-HT2C receptors. All 5-HT2 receptor subtypes are linked to the multifunctional phosphoinositide (PI) signalling system. 5-HT3 receptors are considered ion-gated receptors and are also linked to the PI signalling system by an unknown mechanism. The 5-HT2A receptor subtype is the most widely studied of the 5-HT receptors in psychiatric disorders (for example, suicide, depression and schizophrenia) as well as in relation to the mechanism of action of antidepressant drugs. The roles of 5-HT2C and 5-HT3 receptors in psychiatric disorders are less clear. These 5-HT receptors also play an important role in alcoholism. It has been shown that 5-HT2A, 5-HT2C and 5-HT3 antagonists cause attenuation of alcohol intake in animals and humans. However, the exact mechanisms are unknown. The recent cloning of the cDNAs for 5-HT2A, 5-HT2C and 5-HT3 receptors provides the opportunity to explore the molecular mechanisms responsible for the alterations in these receptors during illness as well as pharmacotherapy. This review article will focus on the current research into the pharmacological properties, molecular biology, and clinical correlates of 5-HT2A, 5-HT2C and 5-HT3 receptors. PMID:7786883

  19. Antidepressant, Antipsychotic, and Hallucinogen Drugs for the Treatment of Psychiatric Disorders: A Convergence at the Serotonin-2A Receptor.

    PubMed

    Howland, Robert H

    2016-07-01

    Antidepressant, atypical antipsychotic, and hallucinogen drugs mediate their actions in part by interactions with the serotonin-2A (5HT2A) receptor. Serotonergic hallucinogen drugs, such as psilocybin, bind most potently as agonists at the 5HT2A receptor, producing profound changes in perception, mood, and cognition. Some of these drugs have been or are currently being investigated in small Phase 2 studies for depression, alcoholism, smoking cessation, anxiety, and posttraumatic stress disorder. However, unlike the synergistic effects of combining antidepressant and atypical antipsychotic drugs, the potential therapeutic effects of hallucinogen drugs may be attenuated by the concurrent use of these medications because antidepressant and atypical antipsychotic drugs desensitize and/or down-regulate 5HT2A receptors. This finding has important implications for optimizing the potential therapeutic use of hallucinogen drugs in psychiatry. [Journal of Psychosocial Nursing and Mental Health Services, 54(7), 21-24.]. PMID:27362381

  20. Structure and function of the third intracellular loop of the 5-hydroxytryptamine2A receptor: the third intracellular loop is alpha-helical and binds purified arrestins.

    PubMed

    Gelber, E I; Kroeze, W K; Willins, D L; Gray, J A; Sinar, C A; Hyde, E G; Gurevich, V; Benovic, J; Roth, B L

    1999-05-01

    Understanding the precise structure and function of the intracellular domains of G protein-coupled receptors is essential for understanding how receptors are regulated, and how they transduce their signals from the extracellular milieu to intracellular sites. To understand better the structure and function of the intracellular domain of the 5-hydroxytryptamine2A (5-HT2A) receptor, a model G(alpha)q-coupled receptor, we overexpressed and purified to homogeneity the entire third intracellular loop (i3) of the 5-HT2A receptor, a region previously implicated in G-protein coupling. Circular dichroism spectroscopy of the purified i3 protein was consistent with alpha-helical and beta-loop, -turn, and -sheet structure. Using random peptide phage libraries, we identified several arrestin-like sequences as i3-interacting peptides. We subsequently found that all three known arrestins (beta-arrestin, arrestin-3, and visual arrestin) bound specifically to fusion proteins encoding the i3 loop of the 5-HT(2A) receptor. Competition binding studies with synthetic and recombinant peptides showed that the middle portion of the i3 loop, and not the extreme N and C termini, was likely to be involved in i3-arrestin interactions. Dual-label immunofluorescence confocal microscopic studies of rat cortex indicated that many cortical pyramidal neurons coexpressed arrestins (beta-arrestin or arrestin-3) and 5-HT2A receptors, particularly in intracellular vesicles. Our results demonstrate (a) that the i3 loop of the 5-HT2A receptor represents a structurally ordered domain composed of alpha-helical and beta-loop, -turn, and -sheet regions, (b) that this loop interacts with arrestins in vitro, and is hence active, and (c) that arrestins are colocalized with 5-HT2A receptors in vivo.

  1. Interaction of psychoactive tryptamines with biogenic amine transporters and serotonin receptor subtypes

    PubMed Central

    Blough, Bruce E.; Landavazo, Antonio; Decker, Ann M.; Partilla, John S.; Baumann, Michael H.; Rothman, Richard B.

    2014-01-01

    Rationale Synthetic hallucinogenic tryptamines, especially those originally described by Alexander Shulgin, continue to be abused in the United States. The range of subjective experiences produced by different tryptamines suggests that multiple neurochemical mechanisms are involved in their actions, in addition to the established role of agonist activity at serotonin-2A (5-HT2A) receptors. Objectives This study evaluated the interaction of a series of synthetic tryptamines with biogenic amine neurotransmitter transporters and with serotonin (5-HT) receptor subtypes implicated in psychedelic effects. Methods Neurotransmitter transporter activity was determined in rat brain synaptosomes. Receptor activity was determined using calcium mobilization and DiscoveRx PathHunter® assays in HEK293, Gα16-CHO, and CHOk1 cells transfected with human receptors. Results Twenty-one tryptamines were analyzed in transporter uptake and release assays, and 5-HT2A, serotonin 1A (5-HT1A), and 5-HT2A β-arrestin functional assays. Eight of the compounds were found to have 5-HT-releasing activity. Thirteen compounds were found to be 5-HT uptake inhibitors or were inactive. All tryptamines were 5-HT2A agonists with a range of potencies and efficacies, but only a few compounds were 5-HT1A agonists. Most tryptamines recruited β-arrestin through 5-HT2A activation. Conclusions All psychoactive tryptamines are 5-HT2A agonists, but 5-HT transporter (SERT) activity may contribute significantly to the pharmacology of certain compounds. The in vitro transporter data confirm structure-activity trends for releasers and uptake inhibitors whereby releasers tend to be structurally smaller compounds. Interestingly, two tertiary amines were found to be selective substrates at SERT, which dispels the notion that 5-HT-releasing activity is limited only to primary or secondary amines. PMID:24800892

  2. Genetic dysfunction of serotonin 2A receptor hampers response to antidepressant drugs: A translational approach.

    PubMed

    Qesseveur, Gaël; Petit, Anne Cécile; Nguyen, Hai Thanh; Dahan, Lionel; Colle, Romain; Rotenberg, Samuel; Seif, Isabelle; Robert, Pauline; David, Denis; Guilloux, Jean-Philippe; Gardier, Alain M; Verstuyft, Céline; Becquemont, Laurent; Corruble, Emmanuelle; Guiard, Bruno P

    2016-06-01

    Pharmacological studies have yielded valuable insights into the role of the serotonin 2A (5-HT2A) receptor in major depressive disorder (MDD) and antidepressant drugs (ADs) response. However, it is still unknown whether genetic variants in the HTR2A gene affect the therapeutic outcome of ADs and the mechanism underlying the regulation of such response remains poorly described. In this context, a translational human-mouse study offers a unique opportunity to address the possibility that variations in the HTR2A gene may represent a relevant marker to predict the efficacy of ADs. In a first part of this study, we investigated in depressed patients the effect of three HTR2A single nucleotide polymorphisms (SNPs), selected for their potential functional consequences on 5-HT2A receptor (rs6313, rs6314 and rs7333412), on response and remission rates after 3 months of antidepressant treatments. We also explored the consequences of the constitutive genetic inactivation of the 5-HT2A receptor (i.e. in 5-HT2A(-/-) mice) on the activity of acute and prolonged administration of SSRIs. Our clinical data indicate that GG patients for the rs7333412 SNP were less prone to respond to ADs than AA/AG patients. In the preclinical study, we demonstrated that the 5-HT2A receptor exerts an inhibitory influence on the neuronal activity of the serotonergic system after acute administration of SSRIs. However, while the chronic administration of the SSRIs escitalopram or fluoxetine elicited a progressive increased in the firing rate of 5-HT neurons in 5-HT2A(+/+) mice, it failed to do so in 5-HT2A(-/-) mutants. These electrophysiological impairments were associated with a decreased ability of the chronic administration of fluoxetine to stimulate hippocampal plasticity and to produce antidepressant-like activities. Genetic loss of the 5-HT2A receptor compromised the activity of chronic treatment with SSRIs, making this receptor a putative marker to predict ADs response. PMID:26764241

  3. Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens.

    PubMed

    Rickli, Anna; Moning, Olivier D; Hoener, Marius C; Liechti, Matthias E

    2016-08-01

    The present study investigated interactions between the novel psychoactive tryptamines DiPT, 4-OH-DiPT, 4-OH-MET, 5-MeO-AMT, and 5-MeO-MiPT at monoamine receptors and transporters compared with the classic hallucinogens lysergic acid diethylamide (LSD), psilocin, N,N-dimethyltryptamine (DMT), and mescaline. We investigated binding affinities at human monoamine receptors and determined functional serotonin (5-hydroxytryptamine [5-HT]) 5-HT2A and 5-HT2B receptor activation. Binding at and the inhibition of human monoamine uptake transporters and transporter-mediated monoamine release were also determined. All of the novel tryptamines interacted with 5-HT2A receptors and were partial or full 5-HT2A agonists. Binding affinity to the 5-HT2A receptor was lower for all of the tryptamines, including psilocin and DMT, compared with LSD and correlated with the reported psychoactive doses in humans. Several tryptamines, including psilocin, DMT, DiPT, 4-OH-DiPT, and 4-OH-MET, interacted with the serotonin transporter and partially the norepinephrine transporter, similar to 3,4-methylenedioxymethamphetamine but in contrast to LSD and mescaline. LSD but not the tryptamines interacted with adrenergic and dopaminergic receptors. In conclusion, the receptor interaction profiles of the tryptamines predict hallucinogenic effects that are similar to classic serotonergic hallucinogens but also MDMA-like psychoactive properties.

  4. Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens.

    PubMed

    Rickli, Anna; Moning, Olivier D; Hoener, Marius C; Liechti, Matthias E

    2016-08-01

    The present study investigated interactions between the novel psychoactive tryptamines DiPT, 4-OH-DiPT, 4-OH-MET, 5-MeO-AMT, and 5-MeO-MiPT at monoamine receptors and transporters compared with the classic hallucinogens lysergic acid diethylamide (LSD), psilocin, N,N-dimethyltryptamine (DMT), and mescaline. We investigated binding affinities at human monoamine receptors and determined functional serotonin (5-hydroxytryptamine [5-HT]) 5-HT2A and 5-HT2B receptor activation. Binding at and the inhibition of human monoamine uptake transporters and transporter-mediated monoamine release were also determined. All of the novel tryptamines interacted with 5-HT2A receptors and were partial or full 5-HT2A agonists. Binding affinity to the 5-HT2A receptor was lower for all of the tryptamines, including psilocin and DMT, compared with LSD and correlated with the reported psychoactive doses in humans. Several tryptamines, including psilocin, DMT, DiPT, 4-OH-DiPT, and 4-OH-MET, interacted with the serotonin transporter and partially the norepinephrine transporter, similar to 3,4-methylenedioxymethamphetamine but in contrast to LSD and mescaline. LSD but not the tryptamines interacted with adrenergic and dopaminergic receptors. In conclusion, the receptor interaction profiles of the tryptamines predict hallucinogenic effects that are similar to classic serotonergic hallucinogens but also MDMA-like psychoactive properties. PMID:27216487

  5. Modulation of GABA release from the thalamic reticular nucleus by cocaine and caffeine: role of serotonin receptors.

    PubMed

    Goitia, Belén; Rivero-Echeto, María Celeste; Weisstaub, Noelia V; Gingrich, Jay A; Garcia-Rill, Edgar; Bisagno, Verónica; Urbano, Francisco J

    2016-02-01

    Serotonin receptors are targets of drug therapies for a variety of neuropsychiatric and neurodegenerative disorders. Cocaine inhibits the re-uptake of serotonin (5-HT), dopamine, and noradrenaline, whereas caffeine blocks adenosine receptors and opens ryanodine receptors in the endoplasmic reticulum. We studied how 5-HT and adenosine affected spontaneous GABAergic transmission from thalamic reticular nucleus. We combined whole-cell patch clamp recordings of miniature inhibitory post-synaptic currents (mIPSCs) in ventrobasal thalamic neurons during local (puff) application of 5-HT in wild type (WT) or knockout mice lacking 5-HT2A receptors (5-HT2A -/-). Inhibition of mIPSCs frequency by low (10 μM) and high (100 μM) 5-HT concentrations was observed in ventrobasal neurons from 5-HT2A -/- mice. In WT mice, only 100 μM 5-HT significantly reduced mIPSCs frequency. In 5-HT2A -/- mice, NAN-190, a specific 5-HT1A antagonist, prevented the 100 μM 5-HT inhibition while blocking H-currents that prolonged inhibition during post-puff periods. The inhibitory effects of 100 μM 5-HT were enhanced in cocaine binge-treated 5-HT2A -/- mice. Caffeine binge treatment did not affect 5-HT-mediated inhibition. Our findings suggest that both 5-HT1A and 5-HT2A receptors are present in pre-synaptic thalamic reticular nucleus terminals. Serotonergic-mediated inhibition of GABA release could underlie aberrant thalamocortical physiology described after repetitive consumption of cocaine. Our findings suggest that both 5-HT1A , 5-HT2A and A1 receptors are present in pre-synaptic TRN terminals. 5-HT1A and A1 receptors would down-regulate adenylate cyclase, whereas 5-HT1A would also increase the probability of the opening of G-protein-activated inwardly rectifying K(+) channels (GIRK). Sustained opening of GIRK channels would hyperpolarize pre-synaptic terminals activating H-currents, resulting in less GABA release. 5-HT2A -would activate PLC and IP3 , increasing intracellular [Ca(2+) ] and

  6. Serotonin 2A and 2B receptor-induced phrenic motor facilitation: differential requirement for spinal NADPH oxidase activity

    PubMed Central

    MacFarlane, P.M.; Vinit, S.; Mitchell, G.S.

    2011-01-01

    Acute intermittent hypoxia (AIH) facilitates phrenic motor output by a mechanism that requires spinal serotonin (type 2) receptor activation, NADPH oxidase activity and formation of reactive oxygen species (ROS). Episodic spinal serotonin (5-HT) receptor activation alone, without changes in oxygenation, is sufficient to elicit NADPH oxidase-dependent phrenic motor facilitation (pMF). Here we investigated: 1) whether serotonin 2A and/or 2B (5-HT2a/b) receptors are expressed in identified phrenic motor neurons, and 2) which receptor subtype is capable of eliciting NADPH-oxidase-dependent pMF. In anesthetized, artificially ventilated adult rats, episodic C4 intrathecal injections (3 × 6µl injections, 5 min intervals) of a 5-HT2a (DOI) or 5-HT2b (BW723C86) receptor agonist elicited progressive and sustained increases in integrated phrenic nerve burst amplitude (i.e. pMF), an effect lasting at least 90 minutes post-injection for both receptor subtypes. 5-HT2a and 5-HT2b receptor agonist-induced pMF were both blocked by selective antagonists (ketanserin and SB206553, respectively), but not by antagonists to the other receptor subtype. Single injections of either agonist failed to elicit pMF, demonstrating a need for episodic receptor activation. Phrenic motor neurons retrogradely labeled with cholera toxin B fragment expressed both 5-HT2a and 5-HT2b receptors. Pre-treatment with NADPH oxidase inhibitors (apocynin and DPI) blocked 5-HT2b, but not 5-HT2a-induced pMF. Thus, multiple spinal type 2 serotonin receptors elicit pMF, but they act via distinct mechanisms that differ in their requirement for NADPH oxidase activity. PMID:21223996

  7. Dot-blot assay for the low density lipoprotein receptor

    SciTech Connect

    Maggi, F.M.; Catapano, A.L.

    1987-01-01

    We describe a new method for detecting the interaction of low density lipoprotein with its receptor using unmodified nitrocellulose as support for membrane protein. The method is specific and sensitive down to 3 micrograms of membrane protein. Unlabeled LDL, but not HDL, competes with /sup 125/I-labeled LDL for binding, and binding is abolished by pretreatment of the membranes with pronase and is dependent upon the presence of Ca2+. Furthermore, modification of arginine or lysine residues on LDL abolishes the lipoprotein interaction with the receptor protein supported on the nitrocellulose. When the membranes are solubilized with octyl glucoside, purification steps of the receptor can be directly followed with no interference of the detergent, therefore eliminating the need for its removal. The increased expression of LDL receptors on liver membranes from estradiol-treated rats was also demonstrated. We suggest, therefore, that this method can be used to detect the presence of LDL receptors on minute amounts of membrane protein.

  8. Dorsal prefrontal cortical serotonin 2A receptor binding indices are differentially related to individual scores on harm avoidance.

    PubMed

    Baeken, Chris; Bossuyt, Axel; De Raedt, Rudi

    2014-02-28

    Although the serotonergic system has been implicated in healthy as well as in pathological emotional states, knowledge about its involvement in personality is limited. Earlier research on this topic suggests that post-synaptic 5-HT2A receptors could be involved in particular in frontal cortical areas. In drug-naïve healthy individuals, we examined the relationship between these 5-HT2A receptors and the temperament dimension harm avoidance (HA) using 123I-5-I-R91150 single photon emission computed tomography (SPECT). HA is a personality feature closely related to stress, anxiety and depression proneness, and it is thought to be mediated by the serotonergic system. We focused on the prefrontal cortices as these regions are frequently implicated in cognitive processes related to a variety of affective disorders. We found a positive relationship between dorsal prefrontal cortical (DPFC) 5-HT2A receptor binding indices (BI) and individual HA scores. Further, our results suggest that those individuals with a tendency to worry or to ruminate are particularly prone to display significantly higher 5-HT2A receptor BI in the left DPFC. Although we only examined psychologically healthy individuals, this relationship suggests a possible vulnerability for affective disorders. PMID:24412555

  9. 5-HT2 Receptor Regulation of Mitochondrial Genes: Unexpected Pharmacological Effects of Agonists and Antagonists.

    PubMed

    Harmon, Jennifer L; Wills, Lauren P; McOmish, Caitlin E; Demireva, Elena Y; Gingrich, Jay A; Beeson, Craig C; Schnellmann, Rick G

    2016-04-01

    In acute organ injuries, mitochondria are often dysfunctional, and recent research has revealed that recovery of mitochondrial and renal functions is accelerated by induction of mitochondrial biogenesis (MB). We previously reported that the nonselective 5-HT2 receptor agonist DOI [1-(4-iodo-2,5-dimethoxyphenyl)propan-2-amine] induced MB in renal proximal tubular cells (RPTCs). The goal of this study was to determine the role of 5-HT2 receptors in the regulation of mitochondrial genes and oxidative metabolism in the kidney. The 5-HT2C receptor agonist CP-809,101 [2-[(3-chlorophenyl)methoxy]-6-(1-piperazinyl)pyrazine] and antagonist SB-242,084 [6-chloro-2,3-dihydro-5-methyl-N-[6-[(2-methyl-3-pyridinyl)oxy]-3-pyridinyl]-1H-indole-1-carboxyamide dihydrochloride] were used to examine the induction of renal mitochondrial genes and oxidative metabolism in RPTCs and in mouse kidneys in the presence and absence of the 5-HT2C receptor. Unexpectedly, both CP-809,101 and SB-242,084 increased RPTC respiration and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) mRNA expression in RPTCs at 1-10 nM. In addition, CP-809,101 and SB-242,084 increased mRNA expression of PGC-1α and the mitochondrial proteins NADH dehydrogenase subunit 1 and NADH dehydrogenase (ubiquinone) β subcomplex 8 in mice. These compounds increased mitochondrial genes in RPTCs in which the 5-HT2C receptor was downregulated with small interfering RNA and in the renal cortex of mice lacking the 5-HT2C receptor. By contrast, the ability of these compounds to increase PGC-1α mRNA and respiration was blocked in RPTCs treated with 5-HT2A receptor small interfering RNA or the 5-HT2A receptor antagonist eplivanserin. In addition, the 5-HT2A receptor agonist NBOH-2C-CN [4-[2-[[(2-hydroxyphenyl)methyl]amino]ethyl]-2,5-dimethoxybenzonitrile] increased RPTC respiration at 1-100 nM. These results suggest that agonism of the 5-HT2A receptor induces MB and that the classic 5-HT2C receptor agonist CP

  10. Characterisation of human 5-hydroxytryptamine2A and 5-hydroxytryptamine2C receptors expressed in the human neuroblastoma cell line SH-SY5Y: comparative stimulation by hallucinogenic drugs.

    PubMed

    Newton, R A; Phipps, S L; Flanigan, T P; Newberry, N R; Carey, J E; Kumar, C; McDonald, B; Chen, C; Elliott, J M

    1996-12-01

    Stable transfection of the human neuroblastoma cell line SH-SY5Y with the human 5-hydroxytryptamine2A (5-HT2A) or 5-HT2C receptor cDNA produced cell lines demonstrating ligand affinities that correlated closely with those for the corresponding endogenous receptors in human frontal cortex and choroid plexus, respectively. Stimulation of the recombinant receptors by 5-HT induced phosphoinositide hydrolysis with higher potency but lower efficacy at the 5-HT2C receptor (pEC50 = 7.80 +/- 0.06) compared with the 5-HT2A receptor (pEC50 = 7.30 +/- 0.08). Activation of the 5-HT2A receptor caused a transient fourfold increase in intracellular Ca2+ concentration. Whole-cell recordings of cells clamped at -50 mV demonstrated a small inward current (2 pA) in response to 10 microM 5-HT for both receptors. There were no differences in potency or efficacy of phosphoinositide hydrolysis among four hallucinogenic [d-lysergic acid diethylamide (LSD), 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane (DOI), 5-methoxy-N,N-dimethyltryptamine, and mescaline] and three nonhallucinogenic drugs (m-chlorophenylpiperazine, quipazine, and ergotamine). Comparison of equipotent doses producing 20% of the maximal response induced by 5-HT revealed selective activation of the 5-HT2A receptor by LSD and to a lesser degree by DOI, mescaline, and ergotamine. Quipazine and 5-methoxy-N,N-dimethyltryptamine were relatively nonselective, whereas m-chlorophenylpiperazine selectively activated the 5-HT2C receptor. It is unlikely therefore that hallucinosis is mediated primarily by activity at the 5-HT2C receptor, whereas activity at the 5-HT2A receptor may represent an important but not unique mechanism associated with hallucinogenic drug action.

  11. Antagonism of lateral saphenous vein serotonin receptors from steers grazing endophyte-free, wild-type, or novel endophyte-infected tall fescue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pharmacologic profiling of 5-hydroxytryptamine (5HT) receptors of bovine lateral saphenous vein has shown that cattle grazing endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum) have altered responses to ergovaline (ERV), 5HT, 5HT2A and 5HT7 agonists. To determine if 5HT...

  12. Serotonin 2A Receptors in Obsessive-Compulsive Disorder: a Positron Emission Tomography Study with [11C]MDL 100907

    PubMed Central

    Simpson, H. Blair; Slifstein, Mark; Bender, James; Xu, Xiaoyan; Hackett, Elizabeth; Maher, Michael J.; Abi-Dargham, Anissa

    2014-01-01

    Background Serotonergic abnormalities are hypothesized to contribute to obsessive-compulsive disorder (OCD). This study used positron emission tomography (PET) with the radioligand [11C]MDL 100907 to examine whether the distribution of one of the serotonin receptors, the 5-HT2A receptor, is altered in OCD. Methods Nineteen OCD subjects, free of psychiatric medications and depression, and 19 matched healthy controls underwent PET scans following injection of [11C]MDL 100907. Total distribution volumes (VT) were derived by kinetic analysis using the arterial input function. Two measures of 5-HT2A availability were computed (BPND and BPP). Groups were compared using a region of interest (ROI) analysis and voxelwise analysis of spatially normalized parametric maps. ROIs included cortical regions (orbitofrontal, dorsolateral prefrontal, medial prefrontal, anterior cingulate, temporal, parietal, occipital, and insular cortex) and limbic regions (entorhinal cortex, parahippocampal gyrus, and medial temporal lobe). Results No significant group differences were observed in [11C]MDL 100907 BPND or BPP in the ROIs or in the voxelwise analysis of BPND maps. There was a significant correlation in the orbitofrontal cortex between [11C] MDL 100907 binding and age of onset, with earlier age of onset associated with higher binding. Conclusions In contrast to prior reports, people with OCD (free of psychiatric medications and depression) are not characterized as a group by major changes in 5-HT2A availability in cortical or limbic brain regions. Further research is warranted to examine potential differences in 5-HT2A availability between early and late onset OCD and to assess 5-HT2A function in relation to other neurotransmitter systems implicated in OCD. PMID:21855857

  13. The 5-hydroxytryptamine2A receptor antagonist R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl-4-piperidinemethanol (M100907) attenuates impulsivity after both drug-induced disruption (dizocilpine) and enhancement (antidepressant drugs) of differential-reinforcement-of-low-rate 72-s behavior in the rat.

    PubMed

    Ardayfio, Paul A; Benvenga, Mark J; Chaney, Stephen F; Love, Patrick L; Catlow, John; Swanson, Steven P; Marek, Gerard J

    2008-12-01

    Previous work has suggested that N-methyl-d-aspartate (NMDA) receptor antagonism and 5-hydroxytryptamine (5-HT)(2A) receptor blockade may enhance and attenuate, respectively, certain types of impulsivity mediated by corticothalamostriatal circuits. More specifically, past demonstrations of synergistic "antidepressant-like" effects of a 5-HT(2A) receptor antagonist and fluoxetine on differential-reinforcement-of-low-rate (DRL) 72-s schedule of operant reinforcement may speak to the role of 5-HT(2A) receptor blockade with respect to response inhibition as an important prefrontal cortical executive function relating to motor impulsivity. To examine the dynamic range over which 5-HT(2A) receptor blockade may exert effects on impulsivity, [R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl-4-piperidinemethanol] (M100907) was examined both alone and in combination with the psychotomimetic NMDA receptor antagonist dizocilpine [e.g., (-)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate; MK-801] and two different antidepressants, the tricyclic antidepressant desmethylimipramine (DMI) and the monoamine oxidase inhibitor tranylcypromine in rats performing under a DRL 72-s schedule. MK-801 increased the response rate, decreased the number of reinforcers obtained, and exerted a leftward shift in the inter-response time (IRT) distribution as expected. A dose of M100907 that exerted minimal effect on DRL behavior by itself attenuated the psychotomimetic effects of MK-801. Extending previous M100907-fluoxetine observations, addition of a minimally active dose of M100907 to low doses of DMI and tranylcypromine enhanced the antidepressant-like effect of the antidepressants. Therefore, it may be that a tonic excitation of 5-HT(2A) receptors modulates impulsivity and function of corticothalamostriatal circuits over an extensive dynamic range. PMID:18772320

  14. The farnesoid X receptor induces very low density lipoprotein receptor gene expression.

    PubMed

    Sirvent, Audrey; Claudel, Thierry; Martin, Geneviève; Brozek, John; Kosykh, Vladimir; Darteil, Raphaël; Hum, Dean W; Fruchart, Jean-Charles; Staels, Bart

    2004-05-21

    The farnesoid X receptor (FXR) is a nuclear receptor activated by bile acids (BAs). In response to ligand-binding, FXR regulates many genes involved in BA, lipid, and lipoprotein metabolism. To identify new FXR target genes, microarray technology was used to profile total RNA extracted from HepG2 cells treated with the natural FXR agonist chenodeoxycholic acid (CDCA). Interestingly, a significant increase of transcript level of the very low density lipoprotein receptor (VLDLR) was observed. Our data, resulting from selective FXR activation, FXR RNA silencing and FXR-deficient mice, clearly demonstrate that BAs up-regulate VLDLR transcript levels via a FXR-dependent mechanism in vitro in human and in vivo in mouse liver cells.

  15. Activation of mGlu2/3 metabotropic glutamate receptors negatively regulates the stimulation of inositol phospholipid hydrolysis mediated by 5-hydroxytryptamine2A serotonin receptors in the frontal cortex of living mice.

    PubMed

    Molinaro, G; Traficante, A; Riozzi, B; Di Menna, L; Curto, M; Pallottino, S; Nicoletti, F; Bruno, V; Battaglia, G

    2009-08-01

    The interaction between 5-hydroxytryptamine(2A) (5-HT(2A)) serotonin receptors and metabotropic glutamate (mGlu) 2/3 receptors underlies the antipsychotic activity of mGlu2/3 receptor agonists in experimental animals and humans. The molecular nature of this interaction is only partially known. We here report for the first time that pharmacological activation of mGlu2/3 receptors attenuates the stimulation of polyphosphoinositide (PI) hydrolysis mediated by 5-HT(2A) receptors in the frontal cortex of living mice. Mice were injected intracerebroventricularly with [myo-(3)H]inositol and treated with drugs 1 h after a pretreatment with lithium, which blocks the conversion of inositol monophosphate into free inositol. Systemic injection of the mGlu2/3 receptor agonist (-)-2-oxa-4-aminocyclo[3.1.0]hexane-4,6-dicarboxylic acid (LY379268) inhibited the stimulation of PI hydrolysis induced by the hallucinogenic 5-HT(2A) receptor agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) without affecting the stimulation by mGlu1/5 or muscarinic receptors. The action of LY379268 was prevented by the preferential mGlu2/3 receptor antagonist (2S,1'S,2'S)-2-(9-xanthylmethyl)-2-(2'-carboxycyclopropyl)glycine (LY341495). N-(4'-cyano-biphenyl-3-yl)-N-(3-pyridinylmethyl)-ethanesulfonamide hydrochloride (LY566332), a selective mGlu2 receptor enhancer, also reduced DOI-stimulated PI hydrolysis when combined with subthreshold doses of LY379268. Systemic LY379268 inhibited DOI-stimulated PI hydrolysis in mice lacking either mGlu2 or mGlu3 receptors but was inactive in double mGlu2/mGlu3 receptor knockout mice, suggesting that both mGlu2 and mGlu3 receptors interact with 5-HT(2A) receptors. Surprisingly, contrasting results were obtained in cortical slice preparations, where LY379268 amplified both DOI- and 3,5-dihydroxyphenylglycine-stimulated PI hydrolysis. Amplification was abrogated by the mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)pyridine, suggesting that

  16. Aromatic interactions impact ligand binding and function at serotonin 5-HT2C G protein-coupled receptors: receptor homology modelling, ligand docking, and molecular dynamics results validated by experimental studies

    NASA Astrophysics Data System (ADS)

    Córdova-Sintjago, Tania; Villa, Nancy; Fang, Lijuan; Booth, Raymond G.

    2014-02-01

    The serotonin (5-hydroxytryptamine, 5-HT) 5-HT2 G protein-coupled receptor (GPCR) family consists of types 2A, 2B, and 2C that share ∼75% transmembrane (TM) sequence identity. Agonists for 5-HT2C receptors are under development for psychoses; whereas, at 5-HT2A receptors, antipsychotic effects are associated with antagonists - in fact, 5-HT2A agonists can cause hallucinations and 5-HT2B agonists cause cardiotoxicity. It is known that 5-HT2A TM6 residues W6.48, F6.51, and F6.52 impact ligand binding and function; however, ligand interactions with these residues at the 5-HT2C receptor have not been reported. To predict and validate molecular determinants for 5-HT2C-specific activation, results from receptor homology modelling, ligand docking, and molecular dynamics simulation studies were compared with experimental results for ligand binding and function at wild type and W6.48A, F6.51A, and F6.52A point-mutated 5-HT2C receptors.

  17. Effects of serotonin 2A/1A receptor stimulation on social exclusion processing.

    PubMed

    Preller, Katrin H; Pokorny, Thomas; Hock, Andreas; Kraehenmann, Rainer; Stämpfli, Philipp; Seifritz, Erich; Scheidegger, Milan; Vollenweider, Franz X

    2016-05-01

    Social ties are crucial for physical and mental health. However, psychiatric patients frequently encounter social rejection. Moreover, an increased reactivity to social exclusion influences the development, progression, and treatment of various psychiatric disorders. Nevertheless, the neuromodulatory substrates of rejection experiences are largely unknown. The preferential serotonin (5-HT) 2A/1A receptor agonist, psilocybin (Psi), reduces the processing of negative stimuli, but whether 5-HT2A/1A receptor stimulation modulates the processing of negative social interactions remains unclear. Therefore, this double-blind, randomized, counterbalanced, cross-over study assessed the neural response to social exclusion after the acute administration of Psi (0.215 mg/kg) or placebo (Pla) in 21 healthy volunteers by using functional magnetic resonance imaging (fMRI) and resting-state magnetic resonance spectroscopy (MRS). Participants reported a reduced feeling of social exclusion after Psi vs. Pla administration, and the neural response to social exclusion was decreased in the dorsal anterior cingulate cortex (dACC) and the middle frontal gyrus, key regions for social pain processing. The reduced neural response in the dACC was significantly correlated with Psi-induced changes in self-processing and decreased aspartate (Asp) content. In conclusion, 5-HT2A/1A receptor stimulation with psilocybin seems to reduce social pain processing in association with changes in self-experience. These findings may be relevant to the normalization of negative social interaction processing in psychiatric disorders characterized by increased rejection sensitivity. The current results also emphasize the importance of 5-HT2A/1A receptor subtypes and the Asp system in the control of social functioning, and as prospective targets in the treatment of sociocognitive impairments in psychiatric illnesses.

  18. Effects of serotonin 2A/1A receptor stimulation on social exclusion processing.

    PubMed

    Preller, Katrin H; Pokorny, Thomas; Hock, Andreas; Kraehenmann, Rainer; Stämpfli, Philipp; Seifritz, Erich; Scheidegger, Milan; Vollenweider, Franz X

    2016-05-01

    Social ties are crucial for physical and mental health. However, psychiatric patients frequently encounter social rejection. Moreover, an increased reactivity to social exclusion influences the development, progression, and treatment of various psychiatric disorders. Nevertheless, the neuromodulatory substrates of rejection experiences are largely unknown. The preferential serotonin (5-HT) 2A/1A receptor agonist, psilocybin (Psi), reduces the processing of negative stimuli, but whether 5-HT2A/1A receptor stimulation modulates the processing of negative social interactions remains unclear. Therefore, this double-blind, randomized, counterbalanced, cross-over study assessed the neural response to social exclusion after the acute administration of Psi (0.215 mg/kg) or placebo (Pla) in 21 healthy volunteers by using functional magnetic resonance imaging (fMRI) and resting-state magnetic resonance spectroscopy (MRS). Participants reported a reduced feeling of social exclusion after Psi vs. Pla administration, and the neural response to social exclusion was decreased in the dorsal anterior cingulate cortex (dACC) and the middle frontal gyrus, key regions for social pain processing. The reduced neural response in the dACC was significantly correlated with Psi-induced changes in self-processing and decreased aspartate (Asp) content. In conclusion, 5-HT2A/1A receptor stimulation with psilocybin seems to reduce social pain processing in association with changes in self-experience. These findings may be relevant to the normalization of negative social interaction processing in psychiatric disorders characterized by increased rejection sensitivity. The current results also emphasize the importance of 5-HT2A/1A receptor subtypes and the Asp system in the control of social functioning, and as prospective targets in the treatment of sociocognitive impairments in psychiatric illnesses. PMID:27091970

  19. Effects of serotonin 2A/1A receptor stimulation on social exclusion processing

    PubMed Central

    Preller, Katrin H.; Pokorny, Thomas; Hock, Andreas; Kraehenmann, Rainer; Stämpfli, Philipp; Seifritz, Erich; Scheidegger, Milan; Vollenweider, Franz X.

    2016-01-01

    Social ties are crucial for physical and mental health. However, psychiatric patients frequently encounter social rejection. Moreover, an increased reactivity to social exclusion influences the development, progression, and treatment of various psychiatric disorders. Nevertheless, the neuromodulatory substrates of rejection experiences are largely unknown. The preferential serotonin (5-HT) 2A/1A receptor agonist, psilocybin (Psi), reduces the processing of negative stimuli, but whether 5-HT2A/1A receptor stimulation modulates the processing of negative social interactions remains unclear. Therefore, this double-blind, randomized, counterbalanced, cross-over study assessed the neural response to social exclusion after the acute administration of Psi (0.215 mg/kg) or placebo (Pla) in 21 healthy volunteers by using functional magnetic resonance imaging (fMRI) and resting-state magnetic resonance spectroscopy (MRS). Participants reported a reduced feeling of social exclusion after Psi vs. Pla administration, and the neural response to social exclusion was decreased in the dorsal anterior cingulate cortex (dACC) and the middle frontal gyrus, key regions for social pain processing. The reduced neural response in the dACC was significantly correlated with Psi-induced changes in self-processing and decreased aspartate (Asp) content. In conclusion, 5-HT2A/1A receptor stimulation with psilocybin seems to reduce social pain processing in association with changes in self-experience. These findings may be relevant to the normalization of negative social interaction processing in psychiatric disorders characterized by increased rejection sensitivity. The current results also emphasize the importance of 5-HT2A/1A receptor subtypes and the Asp system in the control of social functioning, and as prospective targets in the treatment of sociocognitive impairments in psychiatric illnesses. PMID:27091970

  20. Deletion of CB2 cannabinoid receptor induces schizophrenia-related behaviors in mice.

    PubMed

    Ortega-Alvaro, Antonio; Aracil-Fernández, Auxiliadora; García-Gutiérrez, María S; Navarrete, Francisco; Manzanares, Jorge

    2011-06-01

    The possible role of the CB(2) receptor (CB(2)r) in psychiatric disorders has been considered. Several animal models use knockout (KO) mice that display schizophrenia-like behaviors and this study evaluated the role of CB(2)r in the regulation of such behaviors. Mice lacking the CB(2)r (CB(2)KO) were challenged in open field, light-dark box, elevated plus-maze, tail suspension, step down inhibitory avoidance, and pre-pulse inhibition tests (PPI). Furthermore, the effects of treatment with cocaine and risperidone were evaluated using the OF and the PPI test. Gene expression of dopamine D(2) (D(2)r), adrenergic-α(2C) (α(2C)r), serotonergic 5-HT(2A) and 5-HT(2C) receptors (5-HT(2A)r and 5-HT(2C)r) were studied by RT-PCR in brain regions related to schizophrenia. Deletion of CB(2)r decreased motor activity in the OF test, but enhanced response to acute cocaine and produced mood-related alterations, PPI deficit, and cognitive impairment. Chronic treatment with risperidone tended to impair PPI in WT mice, whereas it 'normalized' the PPI deficit in CB(2)KO mice. CB(2)KO mice presented increased D(2)r and α(2C)r gene expressions in the prefrontal cortex (PFC) and locus coeruleus (LC), decreased 5-HT(2C)r gene expression in the dorsal raphe (DR), and 5-HT(2A)r gene expression in the PFC. Chronic risperidone treatment in WT mice left α(2C)r gene expression unchanged, decreased D(2)r gene expression (15 μg/kg), and decreased 5-HT(2C)r and 5-HT(2A)r in PFC and DR. In CB(2)KO, the gene expression of D(2)r in the PFC, of α(2C)r in the LC, and of 5-HT(2C)r and 5-HT(2A)r in PFC was reduced; 5-HT(2C)r and 5-HT(2A)r gene expressions in DR were increased after treatment with risperidone. These results suggest that deletion of CB(2)r has a relation with schizophrenia-like behaviors. Pharmacological manipulation of CB(2)r may merit further study as a potential therapeutic target for the treatment of schizophrenia-related disorders. PMID:21430651

  1. Differential contributions of serotonin receptors to the behavioral effects of indoleamine hallucinogens in mice.

    PubMed

    Halberstadt, Adam L; Koedood, Liselore; Powell, Susan B; Geyer, Mark A

    2011-11-01

    Psilocin (4-hydroxy-N,N-dimethyltryptamine) is a hallucinogen that acts as an agonist at 5-HT(1A), 5-HT(2A), and 5-HT(2C) receptors. Psilocin is the active metabolite of psilocybin, a hallucinogen that is currently being investigated clinically as a potential therapeutic agent. In the present investigation, we used a combination of genetic and pharmacological approaches to identify the serotonin (5-HT) receptor subtypes responsible for mediating the effects of psilocin on head twitch response (HTR) and the behavioral pattern monitor (BPM) in C57BL/6J mice. We also compared the effects of psilocin with those of the putative 5-HT(2C) receptor-selective agonist 1-methylpsilocin and the hallucinogen and non-selective serotonin receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT). Psilocin, 1-methylpsilocin, and 5-MeO-DMT induced the HTR, effects that were absent in mice lacking the 5-HT(2A) receptor gene. When tested in the BPM, psilocin decreased locomotor activity, holepoking, and time spent in the center of the chamber, effects that were blocked by the selective 5-HT(1A) antagonist WAY-100635 but were not altered by the selective 5-HT(2C) antagonist SB 242,084 or by 5-HT(2A) receptor gene deletion. 5-MeO-DMT produced similar effects when tested in the BPM, and the action of 5-MeO-DMT was significantly attenuated by WAY-100635. Psilocin and 5-MeO-DMT also decreased the linearity of locomotor paths, effects that were mediated by 5-HT(2C) and 5-HT(1A) receptors, respectively. In contrast to psilocin and 5-MeO-DMT, 1-methylpsilocin (0.6-9.6 mg/kg) was completely inactive in the BPM. These findings confirm that psilocin acts as an agonist at 5-HT(1A), 5-HT(2A), and 5-HT(2C) receptors in mice, whereas the behavioral effects of 1-methylpsilocin indicate that this compound is acting at 5-HT(2A) sites but is inactive at the 5-HT(1A) receptor. The fact that 1-methylpsilocin displays greater pharmacological selectivity than psilocin indicates that 1-methylpsilocin

  2. Serotonin 5-hydroxytryptamine(2A) receptor activation suppresses tumor necrosis factor-alpha-induced inflammation with extraordinary potency.

    PubMed

    Yu, Bangning; Becnel, Jaime; Zerfaoui, Mourad; Rohatgi, Rasika; Boulares, A Hamid; Nichols, Charles D

    2008-11-01

    The G protein-coupled serotonin 5-hydroxytryptamine (5-HT)(2A) receptor is primarily recognized for its role in brain neurotransmission, where it mediates a wide variety of functions, including certain aspects of cognition. However, there is significant expression of this receptor in peripheral tissues, where its importance is largely unknown. We have now discovered that activation of 5-HT(2A) receptors in primary aortic smooth muscle cells provides a previously unknown and extremely potent inhibition of tumor necrosis factor (TNF)-alpha-mediated inflammation. 5-HT(2A) receptor stimulation with the agonist (R)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(R)-DOI] rapidly inhibits a variety of TNF-alpha-mediated proinflammatory markers, including intracellular adhesion molecule 1 (ICAM-1), vascular adhesion molecule 1 (VCAM-1), and interleukin (IL)-6 gene expression, nitric-oxide synthase activity, and nuclear translocation of nuclear factor kappaB, with IC(50) values of only 10 to 20 pM. It is significant that proinflammatory markers can also be inhibited by (R)-DOI hours after treatment with TNF-alpha. With the exception of a few natural toxins, no current drugs or small molecule therapeutics demonstrate a comparable potency for any physiological effect. TNF-alpha-mediated inflammatory pathways have been strongly implicated in a number of diseases, including atherosclerosis, rheumatoid arthritis, psoriasis, type II diabetes, depression, schizophrenia, and Alzheimer's disease. Our results indicate that activation of 5-HT(2A) receptors represents a novel, and extraordinarily potent, potential therapeutic avenue for the treatment of disorders involving TNF-alpha-mediated inflammation. Note that because (R)-DOI can significantly inhibit the effects of TNF-alpha many hours after the administration of TNF-alpha, potential therapies could be aimed not only at preventing inflammation but also treating inflammatory injury that has already occurred or is ongoing. PMID

  3. Collagenase-3 binds to a specific receptor and requires the low density lipoprotein receptor-related protein for internalization

    NASA Technical Reports Server (NTRS)

    Barmina, O. Y.; Walling, H. W.; Fiacco, G. J.; Freije, J. M.; Lopez-Otin, C.; Jeffrey, J. J.; Partridge, N. C.

    1999-01-01

    We have previously identified a specific receptor for collagenase-3 that mediates the binding, internalization, and degradation of this ligand in UMR 106-01 rat osteoblastic osteosarcoma cells. In the present study, we show that collagenase-3 binding is calcium-dependent and occurs in a variety of cell types, including osteoblastic and fibroblastic cells. We also present evidence supporting a two-step mechanism of collagenase-3 binding and internalization involving both a specific collagenase-3 receptor and the low density lipoprotein receptor-related protein. Ligand blot analysis shows that (125)I-collagenase-3 binds specifically to two proteins ( approximately 170 kDa and approximately 600 kDa) present in UMR 106-01 cells. Western blotting identified the 600-kDa protein as the low density lipoprotein receptor-related protein. Our data suggest that the 170-kDa protein is a specific collagenase-3 receptor. Low density lipoprotein receptor-related protein-null mouse embryo fibroblasts bind but fail to internalize collagenase-3, whereas UMR 106-01 and wild-type mouse embryo fibroblasts bind and internalize collagenase-3. Internalization, but not binding, is inhibited by the 39-kDa receptor-associated protein. We conclude that the internalization of collagenase-3 requires the participation of the low density lipoprotein receptor-related protein and propose a model in which the cell surface interaction of this ligand requires a sequential contribution from two receptors, with the collagenase-3 receptor acting as a high affinity primary binding site and the low density lipoprotein receptor-related protein mediating internalization.

  4. MHC Class I Limits Hippocampal Synapse Density by Inhibiting Neuronal Insulin Receptor Signaling

    PubMed Central

    Dixon-Salazar, Tracy J.; Fourgeaud, Lawrence; Tyler, Carolyn M.; Poole, Julianna R.; Park, Joseph J.

    2014-01-01

    Proteins of the major histocompatibility complex class I (MHCI) negatively regulate synapse density in the developing vertebrate brain (Glynn et al., 2011; Elmer et al., 2013; Lee et al., 2014), but the underlying mechanisms remain largely unknown. Here we identify a novel MHCI signaling pathway that involves the inhibition of a known synapse-promoting factor, the insulin receptor. Dominant-negative insulin receptor constructs decrease synapse density in the developing Xenopus visual system (Chiu et al., 2008), and insulin receptor activation increases dendritic spine density in mouse hippocampal neurons in vitro (Lee et al., 2011). We find that genetically reducing cell surface MHCI levels increases synapse density selectively in regions of the hippocampus where insulin receptors are expressed, and occludes the neuronal insulin response by de-repressing insulin receptor signaling. Pharmacologically inhibiting insulin receptor signaling in MHCI-deficient animals rescues synapse density, identifying insulin receptor signaling as a critical mediator of the tonic inhibitory effects of endogenous MHCI on synapse number. Insulin receptors co-immunoprecipitate MHCI from hippocampal lysates, and MHCI unmasks a cytoplasmic epitope of the insulin receptor that mediates downstream signaling. These results identify an important role for an MHCI–insulin receptor signaling pathway in circuit patterning in the developing brain, and suggest that changes in MHCI expression could unexpectedly regulate neuronal insulin sensitivity in the aging and diseased brain. PMID:25164678

  5. N-Benzyl-5-methoxytryptamines as Potent Serotonin 5-HT2 Receptor Family Agonists and Comparison with a Series of Phenethylamine Analogues

    PubMed Central

    2015-01-01

    A series of N-benzylated-5-methoxytryptamine analogues was prepared and investigated, with special emphasis on substituents in the meta position of the benzyl group. A parallel series of several N-benzylated analogues of 2,5-dimethoxy-4-iodophenethylamine (2C-I) also was included for comparison of the two major templates (i.e., tryptamine and phenethylamine). A broad affinity screen at serotonin receptors showed that most of the compounds had the highest affinity at the 5-HT2 family receptors. Substitution at the para position of the benzyl group resulted in reduced affinity, whereas substitution in either the ortho or the meta position enhanced affinity. In general, introduction of a large lipophilic group improved affinity, whereas functional activity often followed the opposite trend. Tests of the compounds for functional activity utilized intracellular Ca2+ mobilization. Function was measured at the human 5-HT2A, 5-HT2B, and 5-HT2C receptors, as well as at the rat 5-HT2A and 5-HT2C receptors. There was no general correlation between affinity and function. Several of the tryptamine congeners were very potent functionally (EC50 values from 7.6 to 63 nM), but most were partial agonists. Tests in the mouse head twitch assay revealed that many of the compounds induced the head twitch and that there was a significant correlation between this behavior and functional potency at the rat 5-HT2A receptor. PMID:25547199

  6. Single cell laser dissection with molecular beacon polymerase chain reaction identifies 2A as the predominant serotonin receptor subtype in hypoglossal motoneurons.

    PubMed

    Zhan, G; Shaheen, F; Mackiewicz, M; Fenik, P; Veasey, S C

    2002-01-01

    We hypothesize that sleep state-dependent withdrawal of serotonin (5-hydroxytryptamine, 5-HT) at upper airway (UAW) dilator motoneurons contributes significantly to sleep-related suppression of dilator muscle activity in obstructive sleep apnea. Identification of 5-HT receptor subtypes involved in postsynaptic facilitation of UAW motoneuron activity may provide pharmacotherapies for this prevalent disorder. We have adapted two assays to provide semi-quantitative measurements of mRNA copy numbers for 5-HT receptor subtypes in single UAW motoneurons. Specifically, soma of 111 hypoglossal (XII) motoneurons in 10 adult male rats were captured using a laser dissection microscope, and then used individually in single round molecular beacon polymerase chain reaction (PCR) for real-time quantitation of 5-HT(2A), 5-HT(2C), 5-HT(3), 5-HT(4), 5-HT(5A), 5-HT(5B), 5-HT(6) or 5-HT(7) receptor. Receptor mRNA copy numbers from single XII motoneurons were compared to control samples from within the XII nucleus and lateral medulla. All 20 motoneuronal soma assayed for the 5-HT(2A) receptor had measurable copy numbers (7028+/-2656 copies/cell). In contrast, copy numbers for the 5-HT(2A) receptor in XII non-motoneuronal (n=17) and lateral medulla (n=15) samples were 81+/-51 copies and 83+/-35 copies, respectively, P<0.05. Seven of 13 XII motoneurons assayed had measurable 5-HT(2C) receptor copy numbers of mRNA (287+/-112 copies/cell). XII soma had minimal 5-HT(3), 5-HT(4), 5-HT(5A), 5-HT(5B), 5-HT(6) or 5-HT(7) receptor mRNA. 5-HT(2A) receptor mRNA presence within XII motoneurons was confirmed with digoxigenin-labeled in situ hybridization. In summary, combined use of laser dissection and molecular beacon PCR revealed 5-HT(2A) receptor as the predominant 5-HT receptor mRNA in XII motoneurons, and identified small quantities of 5-HT(2C) receptor. This information will allow a more complete understanding of serotonergic control of respiratory activity.

  7. Particulate Matter Promotes In Vitro Receptor-Recognizable Low-Density Lipoprotein Oxidation and Dysfunction of Lipid Receptors

    PubMed Central

    Manzano-León, Natalia; Mas-Oliva, Jaime; Sevilla-Tapia, Laura; Morales-Bárcenas, Rocío; Serrano, Jesús; O’Neill, Marie S.; García-Cuellar, Claudia M.; Quintana, Raúl; Vázquez-López, Inés

    2015-01-01

    Particulate matter may promote cardiovascular disease, possibly as a consequence of its oxidative potential. Studies using susceptible animals indicate that particulate matter aggravates atherosclerosis by increasing lipid/macrophage content in plaques. Macrophage lipid uptake requires oxidized low-density lipoprotein and scavenger receptors; same receptors are involved in particulate matter uptake. We studied in vitro particulate matter potential to oxidize low-density lipoproteins and subsequent cell uptake through scavenger receptors. Particulate matter-induced low-density lipoproteins oxidation was evaluated by the thiobarbituric acid assay. Binding/internalization was tested in wild type and scavenger receptor–transfected Chinese hamster ovary cells, and in RAW264.7 cells using fluorescently labeled low-density lipoproteins. Dose-dependent binding/internalization only occurred in scavenger receptor–transfected Chinese hamster ovary cells and RAW264.7 cells. Competition binding/internalization using particles showed that particulate matter induced decreased binding (~50%) and internalization (~70%) of particle-oxidized low-density lipoproteins and native low-density lipoproteins. Results indicate that particulate matter was capable of oxidizing low-density lipoproteins, favoring macrophage internalization, and also altered scavenger and low-density lipoproteins receptor function. PMID:23297186

  8. Antidepressant- and anxiolytic-like activity of 7-phenylpiperazinylalkyl-1,3-dimethyl-purine-2,6-dione derivatives with diversified 5-HT₁A receptor functional profile.

    PubMed

    Partyka, Anna; Chłoń-Rzepa, Grażyna; Wasik, Anna; Jastrzębska-Więsek, Magdalena; Bucki, Adam; Kołaczkowski, Marcin; Satała, Grzegorz; Bojarski, Andrzej J; Wesołowska, Anna

    2015-01-01

    Continuing our earlier study in a group of purine-2,6-dione derivatives of long chain arylpiperazines (LCAPs), a series of 8-unsubstituted 7-phenylpiperazin-4-yl-alkyl (4-14) and 7-tetrahydroisoquinolinyl-alkyl (15-17) analogues were synthesized and their serotonin 5-HT1A, 5-HT2A, 5-HT6, 5-HT7 and dopamine D2 receptor affinities were determined. The study allowed us to identify some potent 5-HT1A receptor ligands with additional moderate affinity for 5-HT2A, 5-HT7 and dopamine D2 receptors. Compounds 9, 12, 13 and 14, with the highest 5HT1A receptor affinity, were selected for further functional in vivo studies and behavioural evaluation of antidepressant- and antianxiety-like activity. Compounds 9, 12 and 13 showed features of agonists of pre- and/or post-synaptic 5-HT1A receptors, whereas 14 was classified as an antagonist of postsynaptic sites. Moreover, derivatives 9 and 14 acted as antagonists of 5-HT2A receptors. In behavioural studies, compounds 9 and 13 showed antidepressant-like activity in the mouse forced swim test, and their effects were similar or stronger than those of imipramine. Compounds 9, 12 and 14 displayed potential anxiolytic-like properties in the mouse four-plate test, similar or even greater than those of the reference anxiolytic drug, diazepam.

  9. Aminergic receptors in astrogliotic plaques from patients with multiple sclerosis.

    PubMed

    Zeinstra, Esther; te Riele, Paula; Langlois, Xavier; Wilczak, Nadine; Leysen, Josée; de Keyser, Jacques

    2002-10-11

    Cultured astrocytes express a spectrum of neurotransmitter receptors. However, little is known about these receptors in situ. We previously reported the absence of beta(2) adrenergic receptors on astrocytes in multiple sclerosis (MS). Here we used [(3)H]-radioligands and receptor autoradiography to screen for a variety of other aminergic receptors in six silent chronic astrogliotic plaques in brain tissue obtained from five patients with MS. Dopamine D(1) and histamine H(1) receptors were absent. We detected specific binding for cholinergic muscarinic receptors > dopamine D(2), alpha(1-) and alpha(2)-adrenergic receptors > 5-HT(1A), 5-HT(1B/D), 5-HT(2A), 5-HT(2c), 5-HT(4), and dopamine D(3) receptors. Radiotracers for these aminergic receptors might be useful for studying astrogliosis in patients with MS, and compounds acting at some of these receptors may have potential to modulate astroglial function in MS. PMID:12361847

  10. New halogenated tris-(phenylalkyl)amines as h5-HT2B receptor ligands.

    PubMed

    Kapadia, Nirav; Ahmed, Shahrear; Harding, Wayne W

    2016-07-15

    A series of compounds in which various halogen substituents were incorporated into a phenyl ring of a tris-(phenylalkyl)amine scaffold, was synthesized and evaluated for affinity to h5-HT2 receptors. In general, all compounds were found to have good affinity for the 5-HT2B receptor and were selective over 5-HT2A and 5-HT2C receptors. Compound 9i was the most selective compound in this study and is the highest affinity 5-HT2B receptor ligand bearing a tris-(phenylalkyl)amine scaffold to date. PMID:27261181

  11. Estrogen alters the diurnal rhythm of alpha 1-adrenergic receptor densities in selected brain regions

    SciTech Connect

    Weiland, N.G.; Wise, P.M.

    1987-11-01

    Norepinephrine regulates the proestrous and estradiol-induced LH surge by binding to alpha 1-adrenergic receptors. The density of alpha 1-receptors may be regulated by estradiol, photoperiod, and noradrenergic neuronal activity. We wished to determine whether alpha 1-receptors exhibit a diurnal rhythm in ovariectomized and/or estradiol-treated female rats, whether estradiol regulates alpha 1-receptors in those areas of brain involved with LH secretion and/or sexual behavior, and whether the concentrations of alpha-receptors vary inversely relative to previously reported norepinephrine turnover patterns. Young female rats, maintained on a 14:10 light-dark cycle were ovariectomized. One week later, half of them were outfitted sc with Silastic capsules containing estradiol. Groups of animals were decapitated 2 days later at 0300, 1000, 1300, 1500, 1800, and 2300 h. Brains were removed, frozen, and sectioned at 20 micron. Sections were incubated with (/sup 3/H)prazosin in Tris-HCl buffer, washed, dried, and exposed to LKB Ultrofilm. The densities of alpha 1-receptors were quantitated using a computerized image analysis system. In ovariectomized rats, the density of alpha 1-receptors exhibited a diurnal rhythm in the suprachiasmatic nucleus (SCN), medial preoptic nucleus (MPN), and pineal gland. In SCN and MPN, receptor concentrations were lowest during the middle of the day and rose to peak levels at 1800 h. In the pineal gland, the density of alpha 1-receptors was lowest at middark phase, rose to peak levels before lights on, and remained elevated during the day. Estradiol suppressed the density of alpha 1 binding sites in the SCN, MPN, median eminence, ventromedial nucleus, and the pineal gland but had no effect on the lateral septum. Estrogen treatment altered the rhythm of receptor densities in MPN, median eminence, and the pineal gland.

  12. Low density lipoprotein receptor related protein 1 variant interacts with saturated fatty acids in Puerto Ricans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low density lipoprotein related receptor protein 1 (LRP1) is a multi-functional endocytic receptor that is highly expressed in adipocytes and the hypothalamus. Animal models and in vitro studies support a role for LRP1 in adipocyte metabolism and leptin signaling, but genetic polymorphisms have not ...

  13. Enriched Expression of Serotonin 1B and 2A Receptor Genes in Macaque Visual Cortex and their Bidirectional Modulatory Effects on Neuronal Responses

    PubMed Central

    Watakabe, Akiya; Komatsu, Yusuke; Sadakane, Osamu; Shimegi, Satoshi; Takahata, Toru; Higo, Noriyuki; Tochitani, Shiro; Hashikawa, Tsutomu; Naito, Tomoyuki; Osaki, Hironobu; Sakamoto, Hiroshi; Okamoto, Masahiro; Ishikawa, Ayako; Hara, Shin-ichiro; Akasaki, Takafumi; Sato, Hiromichi

    2009-01-01

    To study the molecular mechanism how cortical areas are specialized in adult primates, we searched for area-specific genes in macaque monkeys and found striking enrichment of serotonin (5-hydroxytryptamine, 5-HT) 1B receptor mRNA, and to a lesser extent, of 5-HT2A receptor mRNA, in the primary visual area (V1). In situ hybridization analyses revealed that both mRNA species were highly concentrated in the geniculorecipient layers IVA and IVC, where they were coexpressed in the same neurons. Monocular inactivation by tetrodotoxin injection resulted in a strong and rapid (<3 h) downregulation of these mRNAs, suggesting the retinal activity dependency of their expression. Consistent with the high expression level in V1, clear modulatory effects of 5-HT1B and 5-HT2A receptor agonists on the responses of V1 neurons were observed in in vivo electrophysiological experiments. The modulatory effect of the 5-HT1B agonist was dependent on the firing rate of the recorded neurons: The effect tended to be facilitative for neurons with a high firing rate, and suppressive for those with a low firing rate. The 5-HT2A agonist showed opposite effects. These results suggest that this serotonergic system controls the visual response in V1 for optimization of information processing toward the incoming visual inputs. PMID:19056862

  14. Neurotransmitter receptor density changes in Pitx3ak mice--a model relevant to Parkinson's disease.

    PubMed

    Cremer, J N; Amunts, K; Graw, J; Piel, M; Rösch, F; Zilles, K

    2015-01-29

    Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by alterations of nigrostriatal dopaminergic neurotransmission. Compared to the wealth of data on the impairment of the dopamine system, relatively limited evidence is available concerning the role of major non-dopaminergic neurotransmitter systems in PD. Therefore, we comprehensively investigated the density and distribution of neurotransmitter receptors for glutamate, GABA, acetylcholine, adrenaline, serotonin, dopamine and adenosine in brains of homozygous aphakia mice being characterized by mutations affecting the Pitx3 gene. This genetic model exhibits crucial hallmarks of PD on the neuropathological, symptomatic and pharmacological level. Quantitative receptor autoradiography was used to characterize 19 different receptor binding sites in eleven brain regions in order to understand receptor changes on a systemic level. We demonstrated striking differential changes of neurotransmitter receptor densities for numerous receptor types and brain regions, respectively. Most prominent, a strong up-regulation of GABA receptors and associated benzodiazepine binding sites in different brain regions and concomitant down-regulations of striatal nicotinic acetylcholine and serotonergic receptor densities were found. Furthermore, the densities of glutamatergic kainate, muscarinic acetylcholine, adrenergic α1 and dopaminergic D2/D3 receptors were differentially altered. These results present novel insights into the expression of neurotransmitter receptors in Pitx3(ak) mice supporting findings on PD pathology in patients and indicating on the possible underlying mechanisms. The data suggest Pitx3(ak) mice as an appropriate new model to investigate the role of neurotransmitter receptors in PD. Our study highlights the relevance of non-dopaminergic systems in PD and for the understanding of its molecular pathology. PMID:25451278

  15. Effect of neoadjuvant chemotherapy on low-density lipoprotein (LDL) receptor and LDL receptor-related protein 1 (LRP-1) receptor in locally advanced breast cancer.

    PubMed

    Pires, L A; Hegg, R; Freitas, F R; Tavares, E R; Almeida, C P; Baracat, E C; Maranhão, R C

    2012-06-01

    Low-density lipoprotein (LDL) receptors are overexpressed in most neoplastic cell lines and provide a mechanism for the internalization and concentration of drug-laden nanoemulsions that bind to these receptors. The aim of the present study was to determine whether the administration of standard chemotherapeutic schemes can alter the expression of LDL and LDL receptor-related protein 1 (LRP-1) receptors in breast carcinoma. Fragments of tumoral and normal breast tissue from 16 consecutive volunteer women with breast cancer in stage II or III were obtained from biopsies before the beginning of neoadjuvant chemotherapy and after chemotherapy, from fragments excised during mastectomy. Tissues were analyzed by immunohistochemistry for both receptors. Because complete response to treatment was achieved in 4 patients, only the tumors from 12 were analyzed. Before chemotherapy, there was overexpression of LDL receptor in the tumoral tissue compared to normal breast tissue in 8 of these patients. LRP-1 receptor overexpression was observed in tumors of 4 patients. After chemotherapy, expression of both receptors decreased in the tumors of 6 patients, increased in 4 and was unchanged in 2. Nonetheless, even when chemotherapy reduced receptors expression, the expression was still above normal. The fact that chemotherapy does not impair LDL receptors expression supports the use of drug carrier systems that target neoplastic cells by the LDL receptor endocytic pathway in patients on conventional chemotherapy.

  16. Effect of neoadjuvant chemotherapy on low-density lipoprotein (LDL) receptor and LDL receptor-related protein 1 (LRP-1) receptor in locally advanced breast cancer

    PubMed Central

    Pires, L.A.; Hegg, R.; Freitas, F.R.; Tavares, E.R.; Almeida, C.P.; Baracat, E.C.; Maranhão, R.C.

    2012-01-01

    Low-density lipoprotein (LDL) receptors are overexpressed in most neoplastic cell lines and provide a mechanism for the internalization and concentration of drug-laden nanoemulsions that bind to these receptors. The aim of the present study was to determine whether the administration of standard chemotherapeutic schemes can alter the expression of LDL and LDL receptor-related protein 1 (LRP-1) receptors in breast carcinoma. Fragments of tumoral and normal breast tissue from 16 consecutive volunteer women with breast cancer in stage II or III were obtained from biopsies before the beginning of neoadjuvant chemotherapy and after chemotherapy, from fragments excised during mastectomy. Tissues were analyzed by immunohistochemistry for both receptors. Because complete response to treatment was achieved in 4 patients, only the tumors from 12 were analyzed. Before chemotherapy, there was overexpression of LDL receptor in the tumoral tissue compared to normal breast tissue in 8 of these patients. LRP-1 receptor overexpression was observed in tumors of 4 patients. After chemotherapy, expression of both receptors decreased in the tumors of 6 patients, increased in 4 and was unchanged in 2. Nonetheless, even when chemotherapy reduced receptors expression, the expression was still above normal. The fact that chemotherapy does not impair LDL receptors expression supports the use of drug carrier systems that target neoplastic cells by the LDL receptor endocytic pathway in patients on conventional chemotherapy. PMID:22570085

  17. Effects of chronic fluoxetine treatment on catalepsy and the immune response in mice with a genetic predisposition to freezing reactions: the roles of types 1A and 2A serotonin receptors and the tph2 and SERT genes.

    PubMed

    Tikhonova, M A; Alperina, E L; Tolstikova, T G; Bazovkina, D V; Di, V Y; Idova, G V; Kulikov, A V; Popova, N K

    2010-06-01

    ASC (Antidepressant-Sensitive Catalepsy) mice, bred for a high predisposition to catalepsy, are characterized by depression-like behavior and decreased immune responses. Chronic administration of fluoxetine, which is a selective serotonin reuptake inhibitor antidepressant widely used in clinical practice, to mice of this strain weakened catalepsy and normalized the number of rosette-forming cells in the spleen. In mice of the parental cataleptic strain CBA/Lac, fluoxetine had no effect on the level of catalepsy or the immune response. Analysis of the effects of fluoxetine on the functional activity of 5-HT(1A) and 5-HT(2A) receptors, and the expression of 5-HT(1A) receptor genes in the frontal cortex and midbrain and 5-HT(2A) receptors in the frontal cortex, as well as the tryptophan hydroxylase-2 and the serotonin transporter genes in the midbrain showed that the antidepressant had no effect on these parameters in ASC mice, but decreased the functional activity of 5-HT(2A) receptors in CBA/Lac mice. The possibility that the actions of fluoxetine on catalepsy and the immune response in mice with depression-like states are mediated via other serotoninergic mechanisms is discussed.

  18. Sex, social status, and CRF receptor densities in naked mole-rats.

    PubMed

    Beery, Annaliese K; Bicks, Lucy; Mooney, Skyler J; Goodwin, Nastacia L; Holmes, Melissa M

    2016-02-01

    Naked mole-rats (Heterocephalus glaber) live in groups that are notable for their large size and caste structure, with breeding monopolized by a single female and a small number of males. Recent studies have demonstrated substantial differences between the brains of breeders and subordinates induced by changes in social standing. Corticotropin-releasing factor (CRF) receptors-which bind the hormone CRF as well as related peptides-are important regulators of stress and anxiety, and are emerging as factors affecting social behavior. We conducted autoradiographic analyses of CRF1 and CRF2 receptor binding densities in female and male naked mole-rats varying in breeding status. Both globally and in specific brain regions, CRF1 receptor densities varied with breeding status. CRF1 receptor densities were higher in subordinates across brain regions, and particularly in the piriform cortex and cortical amygdala. Sex differences were present in CRF2 receptor binding densities, as is the case in multiple vole species. CRF2 receptor densities were higher in females, both globally and in the cortical amygdala and lateral amygdalar nucleus. These results provide novel insights into the neurobiology of social hierarchy in naked mole-rats, and add to a growing body of work that links changes in the CRF system with social behavior.

  19. Imidazoline I2 receptor density increases with the malignancy of human gliomas

    PubMed Central

    Callado, L; Martin-Gomez, J; Ruiz, J; Garibi, J; Meana, J

    2004-01-01

    Objective: To investigate the feasibility of using the measurement of imidazoline I2 receptor expression to differentiate glial tumours from other types of brain tumours and for grading the different gliomas. Methods: The specific binding of [3H]idazoxan to imidazoline I2 receptors was measured in homogenates from human gliomas of different grades. Results: The density of imidazoline I2 receptors was significantly greater in the three types of malignant glial tumours than in postmortem control brain or non-glial tumours. The increase in density correlated with the malignancy grade of the gliomas. No significant differences in affinity values were observed. Conclusion: These results suggest that the density of imidazoline I2 receptors may be a useful radioligand parameter for the differentiation of glial tumours from other types of brain tumours and for grading the different gliomas. PMID:15090584

  20. Effects of serotonin on expression of the LDL receptor family member LR11 and 7-ketocholesterol-induced apoptosis in human vascular smooth muscle cells

    SciTech Connect

    Nagayama, Daiji; Ishihara, Noriko; Bujo, Hideaki; Shirai, Kohji; Tatsuno, Ichiro

    2014-04-18

    Highlights: • The dedifferentiation of VSMCs in arterial intima is involved in atherosclerosis. • 5-HT showed proliferative effect on VSMCs which was abolished by sarpogrelate. • 5-HT enhanced expression of LR11 mRNA in VSMCs which was abolished by sarpogrelate. • 5-HT suppressed 7KCHO-induced apoptosis of VSMCs via caspase-3/7-dependent pathway. • The mechanisms explain the 5-HT-induced remodeling of arterial structure. - Abstract: Serotonin (5-HT) is a known mitogen for vascular smooth muscle cells (VSMCs). The dedifferentiation and proliferation/apoptosis of VSMCs in the arterial intima represent one of the atherosclerotic changes. LR11, a member of low-density lipoprotein receptor family, may contribute to the proliferation of VSMCs in neointimal hyperplasia. We conducted an in vitro study to investigate whether 5-HT is involved in LR11 expression in human VSMCs and apoptosis of VSMCs induced by 7-ketocholesterol (7KCHO), an oxysterol that destabilizes plaque. 5-HT enhanced the proliferation of VSMCs, and this effect was abolished by sarpogrelate, a selective 5-HT2A receptor antagonist. Sarpogrelate also inhibited the 5-HT-enhanced LR11 mRNA expression in VSMCs. Furthermore, 5-HT suppressed the 7KCHO-induced apoptosis of VSMCs via caspase-3/7-dependent pathway. These findings provide new insights on the changes in the differentiation stage of VSMCs mediated by 5-HT.

  1. In dystrophic hamsters losartan affects control of ventilation and dopamine D1 receptor density.

    PubMed

    Schlenker, Evelyn H

    2010-08-31

    The BIO 14.6 hamster (DV), an animal model of limb-girdle muscular dystrophy, has elevated angiotensin AT1 receptors that may affect ventilation. Moreover, AT1 receptors may modulate expression of dopamine D1 receptors. We investigated if chronic treatment of BIO 14.6 hamsters (DL) with losartan, an AT1 receptor blocker, affects D1 receptor density in the striatum and nucleus tractus solitarius (NTS) and normalizes ventilation during exposure to air, hypoxia, following hypoxia, and hypercapnia, Ventilation was evaluated using plethysmography. Compared to the golden Syrian hamsters (GS), DV hamsters exhibited lower hypercapnic and hypoxic responsiveness and ventilation during hypercapnic exposure. Relative to GS, DL hamsters increased breathing frequency in air and maintained ventilation during hypercapnia. Post-hypoxic minute ventilation decline occurred in DV but not in DL or GS hamsters. DL hamsters exhibited higher D1 receptor density in the striatum and NTS relative to DV hamsters. Thus, in dystrophic hamsters chronic losartan treatment stimulated frequency of breathing and increased the density of D1 receptors.

  2. Acetylcholine receptor clustering is triggered by a change in the density of a nonreceptor molecule

    PubMed Central

    1990-01-01

    Acetylcholine receptors become clustered at the neuromuscular junction during synaptogenesis, at least in part via lateral migration of diffusely expressed receptors. We have shown previously that electric fields initiate a specific receptor clustering event which is dependent on lateral migration in aneural muscle cell cultures (Stollberg, J., and S. E. Fraser. 1988. J. Cell Biol. 107:1397-1408). Subsequent work with this model system ruled out the possibility that the clustering event was triggered by increasing the receptor density beyond a critical threshold (Stollberg, J., and S. E. Fraser. 1990. J. Neurosci. 10:247-255). This leaves two possibilities: the clustering event could be triggered by the field-induced change in the density of some other molecule, or by a membrane voltage-sensitive mechanism (e.g., a voltage- gated calcium signal). Electromigration is a slow, linear process, while voltage-sensitive mechanisms respond in a rapid, nonlinear fashion. Because of this the two possibilities make different predictions about receptor clustering behavior in response to pulsed or alternating electric fields. In the present work we have studied subcellular calcium distributions, as well as receptor clustering, in response to such fields. Subcellular calcium distributions were quantified and found to be consistent with the predicted nonlinear response. Receptor clustering, however, behaves in accordance with the predictions of a linear response, consistent with the electromigration hypothesis. The experiments demonstrate that a local increase in calcium, or, more generally, a voltage-sensitive mechanism, is not sufficient and probably not necessary to trigger receptor clustering. Experiments with slowly alternating electric fields confirm the view that the clustering of acetylcholine receptors is initiated by a local change in the density of some non-receptor molecule. PMID:2229185

  3. Distinct Hepatic Receptors for Low Density Lipoprotein and Apolipoprotein E in Humans

    NASA Astrophysics Data System (ADS)

    Hoeg, Jeffrey M.; Demosky, Stephen J.; Gregg, Richard E.; Schaefer, Ernst J.; Brewer, H. Bryan

    1985-02-01

    Since the liver is a central organ for lipid and lipoprotein synthesis and catabolism, hepatic receptors for specific apolipoproteins on plasma lipoproteins would be expected to modulate lipid and lipoprotein metabolism. The role of hepatic receptors for low density lipoproteins and apolipoprotein E-containing lipoproteins was evaluated in patients with complementary disorders in lipoprotein metabolism: abetalipoproteinemia and homozygous familial hypercholesterolemia. In addition, hepatic membranes from a patient with familial hypercholesterolemia were studied and compared before and after portacaval shunt surgery. The results establish that the human liver has receptors for apolipoproteins B and E. Furthermore, in the human, hepatic receptors for low density lipoproteins and apolipoprotein E are genetically distinct and can undergo independent control.

  4. The role of 5-HT7 receptor antagonism in the amelioration of MK-801-induced learning and memory deficits by the novel atypical antipsychotic drug lurasidone.

    PubMed

    Horisawa, Tomoko; Nishikawa, Hiroyuki; Toma, Satoko; Ikeda, Atsushi; Horiguchi, Masakuni; Ono, Michiko; Ishiyama, Takeo; Taiji, Mutsuo

    2013-05-01

    Lurasidone is a novel atypical antipsychotic with high affinity for dopamine D2, serotonin 5-HT7 and 5-HT2A receptors. We previously reported that lurasidone and the selective 5-HT7 receptor antagonist, SB-656104-A improved learning and memory deficits induced by MK-801, an N-methyl-d-aspartate (NMDA) receptor antagonist, in the rat passive avoidance test. In this study, we first examined the role of the 5-HT7 receptor antagonistic activity of lurasidone in its pro-cognitive effect to ameliorate MK-801-induced deficits in the rat passive avoidance test. The 5-HT7 receptor agonist, AS19, (2S)-(+)-5-(1,3,5-trimethylpyrazol-4-yl)-2-(dimethylamino) tetralin, (3 mg/kg, s.c.) completely blocked the attenuating effects of lurasidone (3 mg/kg, p.o.), highlighting the importance of 5-HT7 receptor antagonism in the pro-cognitive effect of lurasidone. AS19 (3 mg/kg, s.c.) also blocked the ameliorating effect of SB-656104-A (10 mg/kg, i.p.) in the same experimental paradigm. To further extend our observation, we next tested whether 5-HT7 receptor antagonism still led to the amelioration of MK-801-induced deficits when combined with D2 and 5-HT2A receptor antagonists, and found that SB-656104-A (10 mg/kg, i.p.) significantly ameliorated MK-801-induced deficits even in the presence of the D2 receptor antagonist raclopride (0.1 mg/kg, s.c.) and 5-HT2A receptor antagonist ketanserin (1 mg/kg, s.c.). Taken together, these results suggest that the 5-HT7 receptor antagonistic activity of lurasidone plays an important role in its effectiveness against MK-801-induced deficits, and may contribute to its pharmacological actions in patients with schizophrenia.

  5. Multiple receptor subtypes mediate the effects of serotonin on rat subfornical organ neurons

    NASA Technical Reports Server (NTRS)

    Scrogin, K. E.; Johnson, A. K.; Schmid, H. A.

    1998-01-01

    The subfornical organ (SFO) receives significant serotonergic innervation. However, few reports have examined the functional effects of serotonin on SFO neurons. This study characterized the effects of serotonin on spontaneously firing SFO neurons in the rat brain slice. Of 31 neurons tested, 80% responded to serotonin (1-100 microM) with either an increase (n = 15) or decrease (n = 10) in spontaneous activity. Responses to serotonin were dose dependent and persisted after synaptic blockade. Excitatory responses could also be mimicked by the 5-hydroxytryptamine (5-HT)2A/2C receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI; 1-10 microM) and could be blocked by the 5-HT2A/2C-receptor antagonist LY-53,857 (10 microM). LY-53,857 unmasked inhibitory responses to serotonin in 56% of serotonin-excited cells tested. Serotonin-inhibited cells were also inhibited by the 5-HT1A-receptor agonist 8-hydroxy-2(di-n-propylamino)tetralin (8-OH-DPAT; 1-10 microM; n = 7). The data indicate that SFO neurons are responsive to serotonin via postsynaptic activation of multiple receptor subtypes. The results suggest that excitatory responses to serotonin are mediated by 5-HT2A or 5-HT2C receptors and that inhibitory responses may be mediated by 5-HT1A receptors. In addition, similar percentages of serotonin-excited and -inhibited cells were also sensitive to ANG II. As such the functional relationship between serotonin and ANG II in the SFO remains unclear.

  6. Support for 5-HT2C receptor functional selectivity in vivo utilizing structurally diverse, selective 5-HT2C receptor ligands and the 2,5-dimethoxy-4-iodoamphetamine elicited head-twitch response model

    PubMed Central

    Canal, Clinton E.; Booth, Raymond G.; Morgan, Drake

    2013-01-01

    There are seemingly conflicting data in the literature regarding the role of serotonin (5-HT) 5-HT2C receptors in the mouse head-twitch response (HTR) elicited by the hallucinogenic 5-HT2A/2B/2C receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI). Namely, both 5-HT2C receptor agonists and antagonists, regarding 5-HT2C receptor-mediated Gq-phospholipase C (PLC) signaling, reportedly attenuate the HTR response. The present experiments tested the hypothesis that both classes of 5-HT2C receptor compounds could attenuate the DOI-elicited-HTR in a single strain of mice, C57Bl/6J. The expected results were considered in accordance with ligand functional selectivity. Commercially-available 5-HT2C agonists (CP 809101, Ro 60-0175, WAY 161503, mCPP, and 1-methylpsilocin), novel 4-phenyl-2-N,N-dimethyl-aminotetralin (PAT)-type 5-HT2C agonists (with 5-HT2A/2B antagonist activity), and antagonists selective for 5-HT2A (M100907), 5-HT2C (SB-242084), and 5-HT2B/2C (SB-206553) receptors attenuated the DOI-elicited-HTR. In contrast, there were differential effects on locomotion across classes of compounds. The 5-HT2C agonists and M100907 decreased locomotion, SB-242084 increased locomotion, SB-206553 resulted in dose-dependent biphasic effects on locomotion, and the PATs did not alter locomotion. In vitro molecular pharmacology studies showed that 5-HT2C agonists potent for attenuating the DOI-elicited-HTR also reduced the efficacy of DOI to activate mouse 5-HT2C receptor-mediated PLC signaling in HEK cells. Although there were differences in affinities of a few compounds at mouse compared to human 5-HT2A or 5-HT2C receptors, all compounds tested retained their selectivity for either receptor, regardless of receptor species. Results indicate that 5-HT2C receptor agonists and antagonists attenuate the DOI-elicited-HTR in C57Bl/6J mice, and suggest that structurally diverse 5-HT2C ligands result in different 5-HT2C receptor signaling outcomes compared to DOI. PMID:23353901

  7. Membrane receptors for very low density lipoprotein (VLDL) inhibitor of lymphocyte proliferation

    SciTech Connect

    Yi, P.I.; Beck, G.; Zucker, S.

    1981-06-01

    Physiologic concentrations of human plasma very low density lipoproteins inhibit the DNA synthesis of lymphocytes stimulated by allogeneic cells or lectins. In this report reachers have compared the effects of isolated lipoproteins (very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL)) and lipoprotein-depleted plasma (LDP) on DNA synthesis by phytohemagglutinin-stimulated human lymphocytes. The relative potency for the inhibition of lymphocyte proliferation was VLDL greater than LDL greater than HDL greater than LDP. Fifty percent inhibition of DNA synthesis was observed at a VLDL protein concentration of 1.5--2.0 microgram/ml. Researchers have further demonstrated the presence of specific receptors for VLDL on human lymphocytes. Native VLDL was more effective than LDL in competing for 125I-VLDL binding sites. Subsequent to binding to lymphocytes, 125I-VLDL was internalized and degraded to acid-soluble products. Based on a Scatchard analysis of VLDL binding at 4 degrees C, the number of VLDL receptors per lymphocyte was estimated at 28,000 +/- 1300. Based on an estimated mean binding affinity for the VLDL receptor complex at half saturation of approximately 8.8 X 10(7) liter/mole, it is estimated that 91% of lymphocyte VLDL receptors are occupied at physiologic VLDL concentrations in blood. Although the immune regulatory role of plasma lipoproteins is uncertain, researchers suggest tha VLDL and LDL-In may maintain circulating blood lymphocytes in a nonproliferative state via their respective cell receptor mechanisms.

  8. Dynamic dual-tracer MRI-guided fluorescence tomography to quantify receptor density in vivo

    PubMed Central

    Davis, Scott C.; Samkoe, Kimberley S.; Tichauer, Kenneth M.; Sexton, Kristian J.; Gunn, Jason R.; Deharvengt, Sophie J.; Hasan, Tayyaba; Pogue, Brian W.

    2013-01-01

    The up-regulation of cell surface receptors has become a central focus in personalized cancer treatment; however, because of the complex nature of contrast agent pharmacokinetics in tumor tissue, methods to quantify receptor binding in vivo remain elusive. Here, we present a dual-tracer optical technique for noninvasive estimation of specific receptor binding in cancer. A multispectral MRI-coupled fluorescence molecular tomography system was used to image the uptake kinetics of two fluorescent tracers injected simultaneously, one tracer targeted to the receptor of interest and the other tracer a nontargeted reference. These dynamic tracer data were then fit to a dual-tracer compartmental model to estimate the density of receptors available for binding in the tissue. Applying this approach to mice with deep-seated gliomas that overexpress the EGF receptor produced an estimate of available receptor density of 2.3 ± 0.5 nM (n = 5), consistent with values estimated in comparative invasive imaging and ex vivo studies. PMID:23671066

  9. The antidepressant effects of curcumin in the forced swimming test involve 5-HT1 and 5-HT2 receptors.

    PubMed

    Wang, Rui; Xu, Ying; Wu, Hong-Li; Li, Ying-Bo; Li, Yu-Hua; Guo, Jia-Bin; Li, Xue-Jun

    2008-01-01

    Curcuma longa is a main constituent of many traditional Chinese medicines, such as Xiaoyao-san, used to manage mental disorders effectively. Curcumin is a major active component of C. longa and its antidepressant-like effect has been previously demonstrated in the forced swimming test. The purpose of this study was to explore the possible contribution of serotonin (5-HT) receptors in the behavioral effects induced by curcumin in this animal model of depression. 5-HT was depleted by the tryptophan hydroxylase inhibitor p-chlorophenylalanine (PCPA, 100 mg/kg, i.p.) prior to the administration of curcumin, and the consequent results showed that PCPA blocked the anti-immobility effect of curcumin in forced swimming test, suggesting the involvement of the serotonergic system. Moreover, pre-treatment of pindolol (10 mg/kg, i.p., a beta-adrenoceptors blocker/5-HT(1A/1B) receptor antagonist), 4-(2'-methoxy-phenyl)-1-[2'-(n-2''-pyridinyl)-p-iodobenzamino-]ethyl-piperazine (p-MPPI, 1 mg/kg, s.c., a selective 5-HT(1A) receptor antagonist), or 1-(2-(1-pyrrolyl)-phenoxy)-3-isopropylamino-2-propanol (isamoltane, 2.5 mg/kg, i.p., a 5-HT(1B) receptor antagonist) was found to prevent the effect of curcumin (10 mg/kg) in forced swimming test. On the other hand, a sub-effective dose of curcumin (2.5 mg/kg, p.o.) produced a synergistic effect when given jointly with (+)-8-hydroxy-2-(di-n-propylamino)tetralin, (8-OH-DPAT, 1 mg/kg, i.p., a 5-HT(1A) receptor agonist), anpirtoline (0.25 mg/kg, i.p., a 5-HT(1B) receptor agonist) or ritanserin (4 mg/kg, i.p., a 5-HT(2A/2C) receptor antagonist), but not with ketanserin (5 mg/kg, i.p., a 5-HT(2A/2C) receptor antagonist with higher affinity to 5-HT(2A) receptor) or R(-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI, 1 mg/kg, i.p., a 5-HT(2A) receptor agonist). Taken together, these results indicate that the antidepressant-like effect of curcumin in the forced swimming test is related to serotonergic system and may be mediated by, at least

  10. Density functional theory and conductivity studies of boron-based anion receptors

    DOE PAGESBeta

    Leung, Kevin; Chaudhari, Mangesh I.; Rempe, Susan B.; Fenton, Kyle R.; Pratt, III, Harry D.; Staiger, Chad L.; Nagasubramanian, Ganesan

    2015-07-10

    Anion receptors that bind strongly to fluoride anions in organic solvents can help dissolve the lithium fluoride discharge products of primary carbon monofluoride (CFx) batteries, thereby preventing the clogging of cathode surfaces and improving ion conductivity. The receptors are also potentially beneficial to rechargeable lithium ion and lithium air batteries. We apply Density Functional Theory (DFT) to show that an oxalate-based pentafluorophenyl-boron anion receptor binds as strongly, or more strongly, to fluoride anions than many phenyl-boron anion receptors proposed in the literature. Experimental data shows marked improvement in electrolyte conductivity when this oxalate anion receptor is present. The receptor ismore » sufficiently electrophilic that organic solvent molecules compete with F– for boron-site binding, and specific solvent effects must be considered when predicting its F– affinity. To further illustrate the last point, we also perform computational studies on a geometrically constrained boron ester that exhibits much stronger gas-phase affinity for both F– and organic solvent molecules. After accounting for specific solvent effects, however, its net F– affinity is about the same as the simple oxalate-based anion receptor. Lastly, we propose that LiF dissolution in cyclic carbonate organic solvents, in the absence of anion receptors, is due mostly to the formation of ionic aggregates, not isolated F– ions.« less

  11. Density functional theory and conductivity studies of boron-based anion receptors

    SciTech Connect

    Leung, Kevin; Chaudhari, Mangesh I.; Rempe, Susan B.; Fenton, Kyle R.; Pratt, III, Harry D.; Staiger, Chad L.; Nagasubramanian, Ganesan

    2015-07-10

    Anion receptors that bind strongly to fluoride anions in organic solvents can help dissolve the lithium fluoride discharge products of primary carbon monofluoride (CFx) batteries, thereby preventing the clogging of cathode surfaces and improving ion conductivity. The receptors are also potentially beneficial to rechargeable lithium ion and lithium air batteries. We apply Density Functional Theory (DFT) to show that an oxalate-based pentafluorophenyl-boron anion receptor binds as strongly, or more strongly, to fluoride anions than many phenyl-boron anion receptors proposed in the literature. Experimental data shows marked improvement in electrolyte conductivity when this oxalate anion receptor is present. The receptor is sufficiently electrophilic that organic solvent molecules compete with F for boron-site binding, and specific solvent effects must be considered when predicting its F affinity. To further illustrate the last point, we also perform computational studies on a geometrically constrained boron ester that exhibits much stronger gas-phase affinity for both F and organic solvent molecules. After accounting for specific solvent effects, however, its net F affinity is about the same as the simple oxalate-based anion receptor. Lastly, we propose that LiF dissolution in cyclic carbonate organic solvents, in the absence of anion receptors, is due mostly to the formation of ionic aggregates, not isolated F ions.

  12. Neuronal low-density lipoprotein receptor-related protein 1 binds and endocytoses prion fibrils via receptor cluster 4

    PubMed Central

    Jen, Angela; Parkyn, Celia J.; Mootoosamy, Roy C.; Ford, Melanie J.; Warley, Alice; Liu, Qiang; Bu, Guojun; Baskakov, Ilia V.; Moestrup, Søren; McGuinness, Lindsay; Emptage, Nigel; Morris, Roger J.

    2010-01-01

    For infectious prion protein (designated PrPSc) to act as a template to convert normal cellular protein (PrPC) to its distinctive pathogenic conformation, the two forms of prion protein (PrP) must interact closely. The neuronal receptor that rapidly endocytoses PrPC is the low-density lipoprotein receptor-related protein 1 (LRP1). We show here that on sensory neurons LRP1 is also the receptor that binds and rapidly endocytoses smaller oligomeric forms of infectious prion fibrils, and recombinant PrP fibrils. Although LRP1 binds two molecules of most ligands independently to its receptor clusters 2 and 4, PrPC and PrPSc fibrils bind only to receptor cluster 4. PrPSc fibrils out-compete PrPC for internalization. When endocytosed, PrPSc fibrils are routed to lysosomes, rather than recycled to the cell surface with PrPC. Thus, although LRP1 binds both forms of PrP, it traffics them to separate fates within sensory neurons. The binding of both to ligand cluster 4 should enable genetic modification of PrP binding without disrupting other roles of LRP1 essential to neuronal viability and function, thereby enabling in vivo analysis of the role of this interaction in controlling both prion and LRP1 biology. PMID:20048341

  13. The low density lipoprotein receptor-related protein/alpha2-macroglobulin receptor is a receptor for connective tissue growth factor.

    PubMed

    Segarini, P R; Nesbitt, J E; Li, D; Hays, L G; Yates, J R; Carmichael, D F

    2001-11-01

    Connective tissue growth factor (CTGF) expression is regulated by transforming growth factor-beta (TGF-beta) and strong up-regulation occurs during wound healing; in situ hybridization data indicate that there are high levels of CTGF expression in fibrotic lesions. Recently the binding parameters of CTGF to both high and lower affinity cell surface binding components have been characterized. Affinity cross-linking and SDS-polyacrylamide gel electrophoresis analysis demonstrated the binding of CTGF to a cell surface protein with a mass of approximately 620 kDa. We report here the purification of this protein by affinity chromatography on CTGF coupled to Sepharose and sequence information obtained by mass spectroscopy. The binding protein was identified as the multiligand receptor, low density lipoprotein receptor-related protein/alpha2-macroglobulin receptor (LRP). The identification of LRP as a receptor for CTGF was validated by several studies: 1) binding competition with many ligands that bind to LRP, including receptor-associated protein; 2) immunoprecipitation of CTGF-receptor complex with LRP antibodies; and 3) cells that are genetically deficient for LRP were unable to bind CTGF. Last, CTGF is rapidly internalized and degraded and this process is LRP-dependent. In summary, our data indicate that LRP is a receptor for CTGF, and may play an important role in mediating CTGF biology.

  14. Corticotropin-releasing factor receptor densities vary with photoperiod and sociality.

    PubMed

    Beery, Annaliese K; Vahaba, Daniel M; Grunberg, Diana M

    2014-11-01

    Life in social groups relies on prosocial behaviors as well as on reduction of antisocial behaviors such as aggression and territoriality. The mechanisms supporting variation in behaviors that give rise to group living (sociality) are largely unknown. Female meadow voles exhibit natural seasonal variation in sociality: females are aggressive and territorial in summer, while in winter they share burrows and nest in mixed-sex groups. This behavioral shift is paralleled in the lab by day length-dependent variation in partner preference formation and social huddling. We exploit natural variation in meadow vole sociality in order to examine changes in neural pathways that coincide with environmental and behavioral variations. Mounting evidence suggests that the corticotropin-releasing factor system, encompassing multiple peptides and two receptor subtypes (CRF1 and CRF2), may play an important role in regulating social behaviors. We report day-length dependent variation in CRF1 and CRF2 receptor binding in female meadow voles, and relate these findings to previously collected oxytocin receptor (OTR) binding data and behavioral data for the same individuals. CRF1 receptor binding was greater in summer-like long day lengths (LD), particularly in the hippocampus, while CRF2 receptor binding was greater in winter-like short day lengths (SD) in the cingulate cortex and hippocampus. OTR varied with day length in the bed nucleus of the stria terminalis, nucleus accumbens, and hippocampus. SD voles huddled more extensively than LD voles, and greater huddling time was associated with more CRF1 receptor binding and less CRF2 receptor binding in subregions of the lateral septum. CRF2 receptor associations with behavior mirrored those of OTR in the lateral septum. Finally, estradiol treatment affected density of CRF receptors in multiple brain regions. CRF receptors and their ligands are promising candidates for enhancing understanding of the regulation of non-sexual social

  15. Electron density topography based model to explore N-methyl-D-aspartate receptor channel blockers

    NASA Astrophysics Data System (ADS)

    Ingle, Snehal V.; Joshi, Kaustubh A.

    2016-03-01

    The dwell time of a molecule in a voltage dependent NMDA receptor channel is an important factor in defining its activity as channel blocker. A model has been designed, based on quantum chemical descriptors like geometrical parameters, charge distribution, electron density topography and global reactivity descriptors, to shed lights on the dwell time of a channel blocker. Structure and charge distribution studies indicate polarization of molecules with the electron density located at the core of the molecule. Electron density topography reveals ring critical point (ρrcp), emerging as a signature parameter to understand the dwell time of a channel blocker molecule.

  16. Investigation of the role of 5-HT2 receptor subtypes in the control of the bladder and the urethra in the anaesthetized female rat

    PubMed Central

    Mbaki, Y; Ramage, A G

    2008-01-01

    Background and purpose: Micturition is controlled by central 5-HT-containing pathways. 5-HT2 receptors have been implicated in this system especially in control of the urethra, which is a drug target for treating urinary incontinence. This study investigates the role of each of the three subtypes of this receptor with emphasis on sphincter regulation. Experimental approach: Recordings of urethral and bladder pressure, external urethral sphincter (EUS) EMG, as well as the micturition reflex induced by bladder distension along with blood pressure and heart rate were made in anaesthetized rats. The effects of agonists and antagonists for 5-HT2 receptor subtypes were studied on these variables. Key results: The 5-HT2C agonists Ro 60-0175, WAY 161503 and mCPP, i.v., activated the EUS, increased urethral pressure and inhibited the micturition reflex. The effects of Ro 60-0175 on the EUS were blocked by the 5-HT2C antagonist SB 242084 and the 5-HT2A antagonists, ketanserin and MDL 100907. SB 242084 also blocked the inhibitory action on the reflex, while the 5-HT2B antagonist RS 127445 only blocked the increase in urethral pressure. The 5-HT2A receptor agonist DOI given i.v. or i.t. but not i.c.v. activated the EUS. Conclusions and implications: 5-HT2A/2C receptors located in the sacral spinal cord activate the EUS, while central 5-HT2C receptors inhibit the micturition reflex and 5-HT2B receptors, probably at the level of the urethra, increase urethral smooth muscle tone. Furthermore, 5-HT2B and 5-HT2C receptors do not seem to play an important role in the physiological regulation of micturition. PMID:18604238

  17. Role of CRH in the effects of 5-HT-receptor agonists on food intake and metabolic rate.

    PubMed

    Bovetto, S; Rouillard, C; Richard, D

    1996-11-01

    Two series of experiments were conducted to investigate the role of corticotropin-releasing hormone (CRH) in the effects of 5-hydroxytryptamine (5-HT) on energy intake and energy expenditure. The first set of experiments was carried out to confirm the influence of 5-HT1A-, 5-HT1B-, 5-HT2A/2C-receptor agonists on the activation of the hypothalamic-pituitary-adrenal axis. Plasma corticosterone levels were measured, and a double-immunolabeling procedure was used to determine whether the neuronal activity marker, c-Fos protein (Fos), could be found within brain neurons containing CRH after treatments with 5-HT1A-, 5-HT1B-, 5-HT2A/2C-receptor agonists. The second series of experiments was conducted to assess the involvement of CRH in the effects of 5-HT on food intake and metabolic rate (VO2). The effects of the 5-HT1A-, 5-HT1B-, 5-HT2A/2C-receptor agonists on food intake and VO2 were measured in rats treated with the CRH antagonist, alpha-helical CRH-(9-41). In both experiments rats were intraperitoneally injected with either a vehicle (NaCl 0.9%), the 5-HT1A-receptor agonist (+/-)-8-hydroxy-2-(di-n-propylamino) tetralin hydrobromide (8-OH-DPAT), the 5-HT1B-receptor agonist 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole succinate (RU-24969), or the 5-HT2A/2C-receptor agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI). Fos immunoreactivity was detectable within the CRH-containing neurons of the paraventricular nucleus of the hypothalamus (PVH) after injection of each of the 5-HT-receptor agonists used. The CRH antagonist alpha-helical CRH-(9-41) attenuated the increases in metabolic rate induced by DOI and 8-OH-DPAT. alpha-Helical CRH did not, however, prevent the effects of RU-24969 and DOI on either nocturnal metabolic rate or food intake. The present results provide further evidence for a role of CRH in 5-HT-mediated thermogenic effect, which likely involves the 5-HT2A/2C receptor during the day and the 5-HT1A receptor during the night

  18. Decreased striatal dopamine receptor binding in primary focal dystonia: a D2 or D3 defect?

    PubMed Central

    Karimi, Morvarid; Moerlein, Stephen M.; Videen, Tom O.; Luedtke, Robert R.; Taylor, Michelle; Mach, Robert H.; Perlmutter, Joel S.

    2010-01-01

    Dystonia is an involuntary movement disorder characterized by repetitive patterned or sustained muscle contractions causing twisting or abnormal postures. Several lines of evidence suggest that abnormalities of dopaminergic pathways contribute to the pathophysiology of dystonia. In particular dysfunction of D2-like receptors that mediate function of the indirect pathway in the basal ganglia may play a key role. We have demonstrated with positron emission tomography (PET) that patients with primary focal cranial or hand dystonia have reduced putamenal specific binding of [18F]spiperone a non-selective D2-like radioligand with nearly equal affinity for serotonergic 5-HT(2A) sites. We then repeated the study with [18F]N-methyl-benperidol (NMB), a more selective D2-like receptor radioligand with minimal affinity for 5-HT(2A). Surprisingly, there was no decrease in NMB binding in the putamen of subjects with dystonia. Our findings excluded reductions of putamenal uptake greater than 20% with 95% confidence intervals. Following analysis of the in vitro selectivity of NMB and spiperone demonstrated that NMB was highly selective for D2 receptors relative to D3 receptors (200-fold difference in affinity), whereas spiperone has similar affinity for all three of the D2-like receptor subtypes. These findings coupled with other literature suggest that a defect in D3, rather than D2, receptor expression may be associated with primary focal dystonia. PMID:20960437

  19. Pyrrolo[1,3]benzothiazepine-based serotonin and dopamine receptor antagonists. Molecular modeling, further structure-activity relationship studies, and identification of novel atypical antipsychotic agents.

    PubMed

    Campiani, Giuseppe; Butini, Stefania; Fattorusso, Caterina; Catalanotti, Bruno; Gemma, Sandra; Nacci, Vito; Morelli, Elena; Cagnotto, Alfredo; Mereghetti, Ilario; Mennini, Tiziana; Carli, Miriana; Minetti, Patrizia; Di Cesare, M Assunta; Mastroianni, Domenico; Scafetta, Nazzareno; Galletti, Bruno; Stasi, M Antonietta; Castorina, Massimo; Pacifici, Licia; Vertechy, Mario; Di Serio, Stefano; Ghirardi, Orlando; Tinti, Ornella; Carminati, Paolo

    2004-01-01

    Recently we reported the pharmacological characterization of the 9,10-dihydropyrrolo[1,3]benzothiazepine derivative (S)-(+)-8 as a novel atypical antipsychotic agent. This compound had an optimum pK(i) 5-HT(2A)/D(2) ratio of 1.21 (pK(i) 5-HT(2A) = 8.83; pK(i) D(2) = 7.79). The lower D(2) receptor affinity of (S)-(+)-8 compared to its enantiomer was explained by the difficulty in reaching the conformation required to optimally fulfill the D(2) pharmacophore. With the aim of finding novel atypical antipsychotics we further investigated the core structure of (S)-(+)-8, synthesizing analogues with specific substituents; the structure-activity relationship (SAR) study was also expanded with the design and synthesis of other analogues characterized by a pyrrolo[2,1-b][1,3]benzothiazepine skeleton, substituted on the benzo-fused ring or on the pyrrole system. On the 9,10-dihydro analogues the substituents introduced on the pyrrole ring were detrimental to affinity for dopamine and for 5-HT(2A) receptors, but the introduction of a double bond at C-9/10 on the structure of (S)-(+)-8 led to a potent D(2)/5-HT(2A) receptor ligand with a typical binding profile (9f, pK(i) 5-HT(2A)/D(2) ratio of 1.01, log Y = 8.43). Then, to reduce D(2) receptor affinity and restore atypicality on unsaturated analogues, we exploited the effect of specific substitutions on the tricyclic system of 9f. Through a molecular modeling approach we generated a novel series of potential atypical antipsychotic agents, with optimized 5HT(2A)/D(2) receptor affinity ratios and that were easier to synthesize and purify than the reference compound (S)-(+)-8. A number of SAR trends were identified, and among the analogues synthesized and tested in binding assays, 9d and 9m were identified as the most interesting, giving atypical log Y scores respectively 4.98 and 3.18 (pK(i) 5-HT(2A)/D(2) ratios of 1.20 and 1.30, respectively). They had a multireceptor affinity profile and could be promising atypical agents

  20. Stimulation of glutamate receptors in the ventral tegmental area is necessary for serotonin-2 receptor-induced increases in mesocortical dopamine release.

    PubMed

    Pehek, E A; Hernan, A E

    2015-04-01

    Modulation of dopamine (DA) released by serotonin-2 (5-HT2) receptors has been implicated in the mechanism of action of antipsychotic drugs. The mesocortical DA system has been implicated particularly in the cognitive deficits observed in schizophrenia. Agonism at 5-HT2A receptors in the prefrontal cortex (PFC) is associated with increases in cortical DA release. Evidence indicates that 5-HT2A receptors in the cortex regulate mesocortical DA release through stimulation of a "long-loop" feedback system from the PFC to the ventral tegmental area (VTA) and back. However, a causal role for VTA glutamate in the 5-HT2-induced increases in PFC DA has not been established. The present study does so by measuring 5-HT2 agonist-induced DA release in the cortex after infusions of glutamate antagonists into the VTA of the rat. Infusions of a combination of a N-methyl-d-aspartic acid (NMDA) (AP-5: 2-amino-5-phosphopentanoic acid) and an AMPA/kainate (CNQX: 6-cyano-7-nitroquinoxaline-2,3-dione) receptor antagonist into the VTA blocked the increases in cortical DA produced by administration of the 5-HT2 agonist DOI [(±)-2,5-dimethoxy-4-iodoamphetamine] (2.5mg/kg s.c.). These results demonstrate that stimulation of glutamate receptors in the VTA is necessary for 5-HT2 agonist-induced increases in cortical DA.

  1. Stimulation of glutamate receptors in the ventral tegmental area is necessary for serotonin-2 receptor-induced increases in mesocortical dopamine release.

    PubMed

    Pehek, E A; Hernan, A E

    2015-04-01

    Modulation of dopamine (DA) released by serotonin-2 (5-HT2) receptors has been implicated in the mechanism of action of antipsychotic drugs. The mesocortical DA system has been implicated particularly in the cognitive deficits observed in schizophrenia. Agonism at 5-HT2A receptors in the prefrontal cortex (PFC) is associated with increases in cortical DA release. Evidence indicates that 5-HT2A receptors in the cortex regulate mesocortical DA release through stimulation of a "long-loop" feedback system from the PFC to the ventral tegmental area (VTA) and back. However, a causal role for VTA glutamate in the 5-HT2-induced increases in PFC DA has not been established. The present study does so by measuring 5-HT2 agonist-induced DA release in the cortex after infusions of glutamate antagonists into the VTA of the rat. Infusions of a combination of a N-methyl-d-aspartic acid (NMDA) (AP-5: 2-amino-5-phosphopentanoic acid) and an AMPA/kainate (CNQX: 6-cyano-7-nitroquinoxaline-2,3-dione) receptor antagonist into the VTA blocked the increases in cortical DA produced by administration of the 5-HT2 agonist DOI [(±)-2,5-dimethoxy-4-iodoamphetamine] (2.5mg/kg s.c.). These results demonstrate that stimulation of glutamate receptors in the VTA is necessary for 5-HT2 agonist-induced increases in cortical DA. PMID:25637799

  2. Is there a gender difference of somatostatin-receptor density in the human brain?

    PubMed

    Pichler, Robert; Maschek, Wilhelmine; Crespillo, Carmen; Esteva, Isabel; Soriguer, Federico

    2002-01-01

    Animal experiments and observations in human brains have convincingly shown that sexual differentiation not only concerns the genitalia but also the brain. This has been investigated also in the light of a possible explanation of a presumed biological aetiology of transsexuality. The volume of the central subdivision of the bed nucleus of the stria terminalis, a brain area that is essential for sexual behaviour, has been reported to be larger in men than in women. Additionally, the number of somatostatin expressing neurons in this region was shown to be higher in men than in women. As neuronal production of somatostatin is involved the idea is striking whether somatostatin-receptor density in the cortex of cerebral hemispheres might be related to gender identity. We investigated in vivo the density of somatostatin-receptors in selected regions of the human brain in both sexes by means of receptor scintigraphy. Basal ganglia tracer uptake of 111-In-Pentreotide was equally low in both genders at 0,80% +/ 0,26 (related to tracer uptake of the whole brain layer). Temporal cortex accumulated at 2,9% +/ 1,1 in men and at 2,3% +/ 0,76 in women. Frontal brain region had an uptake of 3,0% +/ 1,4 in male and of 2,5% +/ 1,3 in female. This shows a tendency in males for relatively augmented uptake indicating higher somatostatin receptor density in temporal and frontal cerebral cortex.

  3. Functional balance between T cell chimeric receptor density and tumor associated antigen density: CTL mediated cytolysis and lymphokine production.

    PubMed

    Weijtens, M E; Hart, E H; Bolhuis, R L

    2000-01-01

    Genetically engineered expression of tumor-specific single chain antibody chimeric receptors (ch-Rec) on human T lymphocytes endow these cells with the parental monoclonal antibody (mAb) dictated tumor specificity and may be useful for clinical immuno-genetherapy. Therefore it was of importance to assess how the densities of tumor-specific receptors and tumor associated antigens (TAA), respectively, affect primary human T lymphocyte functions in relation to target cell susceptibilities to lysis. We therefore studied the functional balance between ch-Rec densities on human T lymphocytes and TAA on tumor cells. The gene construct encoding a ch-Rec derived from (1) a renal carcinoma cell (RCC) specific mouse mAb (G250), and (2) the human signal transducing Fc(epsilon)RI gamma-chain was used. To obtain ch-RecHIGH-POS and ch-RecLOW-POS T lymphocytes, two distinct retroviral vectors were used to introduce the gene constructs into primary human T lymphocytes. Levels of ch-Rec-redirected T lymphocyte mediated tumor cell lysis, as well as lymphokine production were determined using RCC lines as target/stimulator cells, which express either no or increasing densities of the TAA. A functional and dynamic balance between ch-Rec densities on cytotoxic T lymphocytes (CTLs) on the one hand and TAA densities on RCCs on the other, was found. In short, ch-RecHIGH-POS CTLs are triggered by TAAHIGH-POS as well as TAALOW-POS RCCs to lyse tumor cells and produce (IFN-gamma and TNF-alpha) lymphokine. In contrast, ch-RecLOW-POS T lymphocytes are only triggered for cytolysis and lymphokine production by relatively TAAHIGH-POS RCCs. In conclusion, (1) the activation of T lymphocyte responses is co-determined by the expression levels of the ch-Rec on T lymphocytes and the TAA on tumor cells and (2) at relatively high T lymphocyte ch-Rec expression levels the CTLs lyse tumor cells with a wide range of TAA densities. Gene Therapy (2000) 7, 35-42. PMID:10680014

  4. Receptor-mediated delivery of photoprotective agents by low-density lipoprotein

    SciTech Connect

    Mosley, S.T.; Yang, Y.L.; Falck, J.R.; Anderson, R.G.W.

    1984-12-01

    Low density lipoprotein (LDL) has been used to deliver toxic molecules to cells by receptor-mediated endocytosis. In these studies, the cholesteryl ester core of LDL was replaced with a lipophilic, toxic molecule. The authors report that photoprotective azo dyes can be stably incorporated into LDL, and that this reconstituted LDL protects cells from the photosensitizing action of pyrene methanol (PM) in a receptor-dependent process. The photoprotective action of the azo dye is due to its ability to scavenge singlet oxygen that is produced by the photosensitive agent in response to UV light.

  5. The chemokine receptors ACKR2 and CCR2 reciprocally regulate lymphatic vessel density

    PubMed Central

    Lee, Kit M; Danuser, Renzo; Stein, Jens V; Graham, Delyth; Nibbs, Robert JB; Graham, Gerard J

    2014-01-01

    Macrophages regulate lymphatic vasculature development; however, the molecular mechanisms regulating their recruitment to developing, and adult, lymphatic vascular sites are not known. Here, we report that resting mice deficient for the inflammatory chemokine-scavenging receptor, ACKR2, display increased lymphatic vessel density in a range of tissues under resting and regenerating conditions. This appears not to alter dendritic cell migration to draining lymph nodes but is associated with enhanced fluid drainage from peripheral tissues and thus with a hypotensive phenotype. Examination of embryonic skin revealed that this lymphatic vessel density phenotype is developmentally established. Further studies indicated that macrophages and the inflammatory CC-chemokine CCL2, which is scavenged by ACKR2, are associated with this phenotype. Accordingly, mice deficient for the CCL2 signalling receptor, CCR2, displayed a reciprocal phenotype of reduced lymphatic vessel density. Further examination revealed that proximity of pro-lymphangiogenic macrophages to developing lymphatic vessel surfaces is increased in ACKR2-deficient mice and reduced in CCR2-deficient mice. Therefore, these receptors regulate vessel density by reciprocally modulating pro-lymphangiogenic macrophage recruitment, and proximity, to developing, resting and regenerating lymphatic vessels. PMID:25271254

  6. Receptor density is key to the alpha2/beta interferon differential activities.

    PubMed

    Moraga, Ignacio; Harari, Daniel; Schreiber, Gideon; Uzé, Gilles; Pellegrini, Sandra

    2009-09-01

    Multiple type I interferons (IFN-alpha/beta) elicit Jak/Stat activation, rapid gene induction, and pleiotropic effects, such as differentiation, antiviral protection, and blocks in proliferation, which are dependent on the IFN subtype and the cellular context. To date, ligand- and receptor-specific molecular determinants underlying IFN-alpha/beta differential activities or potencies have been well characterized. To analyze cellular determinants that impact subtype-specific potency, human fibrosarcoma U5A-derived clones, exhibiting a gradient of IFN sensitivity by virtue of increasing receptor levels, were monitored for Jak/Stat signaling, gene induction, cell cycle lengthening, and apoptosis. In cells with scarce receptors, IFN-beta was more potent than IFN-alpha2 in antiproliferative activity, while the two subtypes were equipotent in all other readouts. Conversely, in cells with abundant receptors, IFN-alpha2 matched or even surpassed IFN-beta in all readouts tested. Our results suggest that the differential activities of the IFN subtypes are dictated not only by the intrinsic ligand/receptor binding kinetics but also by the density of cell surface receptor components.

  7. SSRI augmentation of antipsychotic alters expression of GABA(A) receptor and related genes in PMC of schizophrenia patients.

    PubMed

    Silver, Henry; Susser, Ehud; Danovich, Lena; Bilker, Warren; Youdim, Moussa; Goldin, Vladimir; Weinreb, Orly

    2011-06-01

    Clinical studies have shown that negative symptoms of schizophrenia unresponsive to antipsychotic given alone can improve after augmentation with SSRI antidepressant. Laboratory investigations into the mechanism of this synergism showed that co-administration of SSRI and antipsychotic produces changes in GABA(A) receptor and related systems, which differ from the effects of each drug alone. To examine the clinical relevance of these findings, the current study examined the effects of SSRI augmentation treatment on GABA(A) receptor and related systems in schizophrenia patients. Schizophrenia patients with high levels of negative symptoms unresponsive to antipsychotic treatment received add-on fluvoxamine (100 mg/d). Blood was taken before and 1, 3 and 6 wk after adding fluvoxamine and peripheral mononuclear cells (PMC) isolated. RNA encoding for GABA(A)β3, 5-HT2A, and 5-HT7 receptors, PKCβ2, and brain-derived neurotrophic factor (BDNF) was assayed with real-time RT-PCR. Plasma BDNF protein was assayed using ELISA. Clinical symptoms were assessed with validated rating scales. We found significant increase in mRNA encoding for GABA(A)β3 and 5-HT2A, 5-HT7 receptors and BDNF and a reduction in PKCβ2 mRNA. Plasma BDNF protein concentrations were increased. There were significant correlations among the genes. Clinical symptoms improved significantly. mRNA expression of PKCβ2, 5-HT2A and 5-HT7 showed significant associations with clinical symptoms. Combined SSRI+antipsychotic treatment is associated with changes in GABA(A) receptor and in related signalling systems in patients. These changes may be part of the mechanism of clinically effective drug action and may prove to be biomarkers of pharmacological response.

  8. A case of 25I-NBOMe (25-I) intoxication: a new potent 5-HT2A agonist designer drug

    PubMed Central

    Rose, S. Rutherfoord; Poklis, Justin L.; Poklis, Alphonse

    2014-01-01

    Context Abuse of synthetic stimulant compounds resulting in significant toxicity is being increasingly reported by poison centers. Toxicologic assessment is complicated by inconsistent manufacturing processes and limited laboratory testing. We describe a case of self-reported exposure to 25-I (25I-NBOMe), a novel phenethylamine derivative, with subsequent quantification in serum. Case details An 18-year-old male presented to the emergency department (ED) with severe agitation and hallucinations after jumping out of a moving car. He was tachycardiac (150–160 bpm) and hypertensive (150–170 mm Hg systolic and 110 mg Hg diastolic), and required physical restraints and treatment with intravenous lorazepam administration. His symptoms gradually improved and vital signs returned to normal over 48 h, though he continued to have episodes of aggressiveness. An assay was developed by our analytical toxicology laboratory for 25-I, and serum obtained during ED evaluation and treatment was found to contain 0.76 ng/ml of 25-I. Case discussion For 25I-NBOMe, 25-I is a common abbreviation for 25I-NBOMe, which is a (n-benzyl) phenethylamine in the 2C “family.” Initially synthesized for research, cases of self-reported use of 25-I have recently appeared in the literature, some of which contain qualitative urine conf rmation. There are no commercially available quantitative assays, and no previous reports have published serum concentrations. 25-I is a potent new synthetic drug with apparent significant behavioral toxicity that can be detected and quantified in serum. PMID:23473462

  9. Effect of prenatal stress on density of NMDA receptors in rat brain.

    PubMed

    Tavassoli, Elham; Saboory, Ehsan; Teshfam, Masood; Rasmi, Yusef; Roshan-Milani, Shiva; Ilkhanizadeh, Behrooz; Hesari, Ali Kalantari

    2013-12-01

    N-methyl-D-aspartate (NMDA) receptors are important excitatory receptors which contribute to many brain functions. Altered NMDA receptor levels cause maldevelopment of corticostriatal and corticolimbic pathways, which is a neurobiological predisposing factor for development of epilepsy, schizophrenia and other idiopathic psychotic disorders. It was hypothesized that prenatal stress could play a role in pathophysiology of these disorders by affecting expression of the receptors through releasing corticosterone. Sixty-eight virgin female Wistar rats were selected and mated with male rats with the same genotype. Then, the pregnant rats were subjected to restraint or predator stress on 15th, 16th and 17th gestation days. Prenatal stress consisted of restraint or predator stresses of the dams under normal room conditions. After parturition, the pups were studied in terms of density of NMDA receptors in brain at different time points. Meanwhile, blood sample was obtained and corticosterone blood level (CBL) was measured. The pups were then compared with the pups born to unstressed dams. Stress induced significant rise in CBL and NMDA receptors in brain of the offspring. CBL was significantly higher among the stressed rats compared to the control ones; there was significant difference between the two stresses and between the two sexes. The male pups were affected more severely. Stressful events during gestation had important effects on NMDA receptors of the offspring. It can be concluded that stress-induced elevation of NMDA receptors and corticosterone might mediate altered susceptibility to epilepsy and decrease ability of learning and memory and other stress-induced neurologic disorders. PMID:24120877

  10. Multiple, diverse senile plaque-associated proteins are ligands of an apolipoprotein E receptor, the alpha 2-macroglobulin receptor/low-density-lipoprotein receptor-related protein.

    PubMed

    Rebeck, G W; Harr, S D; Strickland, D K; Hyman, B T

    1995-02-01

    Both apolipoprotein E and its receptor, the low-density-lipoprotein receptor-related protein (LRP), are associated with senile plaques in Alzheimer's disease. We examined the relationship of other LRP-related molecules to senile plaques. LRP is a multifunctional receptor that binds and rapidly internalizes at least seven ligands: apolipoprotein E, activated alpha 2-macroglobulin, tissue and urokinase-type plasminogen activators, plasminogen activator inhibitor-1, lipoprotein lipase, and lactoferrin. Using immunohistochemistry, we showed that all of these ligands, representing a diverse group of otherwise apparently unrelated proteins, accumulate on senile plaques. We also studied expression of the receptor-associated protein, a physiological inhibitor of LRP, in the hippocampal formation from normal subjects and Alzheimer's disease patients. Receptor-associated protein colocalizes with LRP on neuronal soma, but not on neuronal processes or reactive astrocytes. It is not present on senile plaques. These results suggest that senile plaque-associated LRP can bind its ligands, but clearance of these compounds may be impaired in the vicinity of senile plaques.

  11. Lectin-like oxidized low-density lipoprotein receptor (LOX-1) in sickle cell disease vasculopathy.

    PubMed

    Chen, Mingyi; Qiu, Hong; Lin, Xin; Nam, David; Ogbu-Nwobodo, Lucy; Archibald, Hannah; Joslin, Amelia; Wun, Ted; Sawamura, Tatsuya; Green, Ralph

    2016-09-01

    Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL. Increased expression of LOX-1 has been demonstrated in atherosclerotic lesions and diabetic vasculopathy. In this study, we investigate the expression of LOX-1 receptor in sickle cell disease (SCD) vasculopathy. Expression of LOX-1 in brain vascular endothelium is markedly increased and LOX-1 gene expression is upregulated in cultured human brain microvascular endothelial cells by incubation with SCD erythrocytes. Also, the level of circulating soluble LOX-1 concentration is elevated in the plasma of SCD patients. Increased LOX-1 expression in endothelial cells is potentially involved in the pathogenesis of SCD vasculopathy. Soluble LOX-1 concentration in SCD may provide a novel biomarker for risk stratification of sickle cell vascular complications. PMID:27519944

  12. Receptor mediated uptake of paclitaxel from a synthetic high density lipoprotein nanocarrier.

    PubMed

    Mooberry, Linda K; Nair, Maya; Paranjape, Sulabha; McConathy, Walter J; Lacko, Andras G

    2010-01-01

    The purpose of these studies was to determine the mechanism(s) whereby paclitaxel (PTX), is taken up by cancer cells, once encapsulated into synthetic/reconstituted high density lipoprotein (rHDL). The uptake of PTX was found to be facilitated by the scavenger receptor type B-1 (SR-B1) when drug-loaded rHDL particles were incubated with cells that express the SRB1 receptor. Studies with double-labeled, PTX containing rHDL nanoparticles showed that prostate cancer (PC-3) cells incorporated PTX primarily via a selective (SR-B1 type) uptake mechanism. In the presence of a 10-fold excess of plasma HDL, PTX uptake decreased to 30% of the control. These findings suggest that the incorporation of lipophilic drugs by cancer cells from rHDL nanoparticles is facilitated by a receptor mediated (SR-B1) mechanism.

  13. Autonomous bacterial localization and gene expression based on nearby cell receptor density

    PubMed Central

    Wu, Hsuan-Chen; Tsao, Chen-Yu; Quan, David N; Cheng, Yi; Servinsky, Matthew D; Carter, Karen K; Jee, Kathleen J; Terrell, Jessica L; Zargar, Amin; Rubloff, Gary W; Payne, Gregory F; Valdes, James J; Bentley, William E

    2013-01-01

    Escherichia coli were genetically modified to enable programmed motility, sensing, and actuation based on the density of features on nearby surfaces. Then, based on calculated feature density, these cells expressed marker proteins to indicate phenotypic response. Specifically, site-specific synthesis of bacterial quorum sensing autoinducer-2 (AI-2) is used to initiate and recruit motile cells. In our model system, we rewired E. coli's AI-2 signaling pathway to direct bacteria to a squamous cancer cell line of head and neck (SCCHN), where they initiate synthesis of a reporter (drug surrogate) based on a threshold density of epidermal growth factor receptor (EGFR). This represents a new type of controller for targeted drug delivery as actuation (synthesis and delivery) depends on a receptor density marking the diseased cell. The ability to survey local surfaces and initiate gene expression based on feature density represents a new area-based switch in synthetic biology that will find use beyond the proposed cancer model here. PMID:23340842

  14. Apolipoprotein E on Hepatitis C Virion Facilitates Infection through Interaction with Low Density Lipoprotein Receptor

    PubMed Central

    Owen, David M.; Huang, Hua; Ye, Jin; Gale, Michael

    2009-01-01

    Hepatitis C virus (HCV) infection is a major cause of liver disease. HCV associates with host apolipoproteins and enters hepatocytes through complex processes involving some combination of CD81, claudin-I, occludin, and scavenger receptor BI. Here we show that infectious HCV resembles very low density lipoprotein (VLDL) and that entry involves co-receptor function of the low density lipoprotein receptor (LDL-R). Blocking experiments demonstrate that β-VLDL itself or anti-apolipoprotein E (apoE) antibody can block HCV entry. Knockdown of the LDL-R by treatment with 25-hydroxycholesterol or siRNA ablated ligand uptake and reduced HCV infection of cells, whereas infection was rescued upon cell ectopic LDL-R expression. Analyses of gradient-fractionated HCV demonstrate that apoE is associated with HCV virions exhibiting peak infectivity and dependence upon the LDL-R for cell entry. Our results define the LDL-R as a cooperative HCV co-receptor that supports viral entry and infectivity through interaction with apoE ligand present in an infectious HCV/lipoprotein complex comprising the virion. Disruption of HCV/LDL-R interactions by altering lipoprotein metabolism may therefore represent a focus for future therapy. PMID:19751943

  15. Packing Density of the Erythropoietin Receptor Transmembrane Domain Correlates with Amplification of Biological Responses

    SciTech Connect

    Becker, Verena; Sengupta, D; Ketteler, Robin; Ullmann, G. Matthias; Smith, Jeremy C; Klingmuller, Ursula

    2008-10-01

    The formation of signal-promoting dimeric or oligomeric receptor complexes at the cell surface is modulated by self-interaction of their transmembrane (TM) domains. To address the importance of TM domain packing density for receptor functionality, we examined a set of asparagine mutants in the TM domain of the erythropoietin receptor (EpoR). We identified EpoR-T242N as a receptor variant that is present at the cell surface similar to wild-type EpoR but lacks visible localization in vesicle-like structures and is impaired in efficient activation of specific signaling cascades. Analysis by a molecular modeling approach indicated an increased interhelical distance for the EpoR-T242N TM dimer. By employing the model, we designed additional mutants with increased or decreased packing volume and confirmed a correlation between packing volume and biological responsiveness. These results propose that the packing density of the TM domain provides a novel layer for fine-tuned regulation of signal transduction and cellular decisions.

  16. In vivo demonstration of altered benzodiazepine receptor density in patients with generalised epilepsy.

    PubMed Central

    Savic, I; Pauli, S; Thorell, J O; Blomqvist, G

    1994-01-01

    Electrophysiological data suggest that an abnormal oscillatory pattern of discharge in cortical and thalamic neurons may be the major mechanism underlying primary generalised epilepsy. No neurochemical or anatomical substrate for this theory has hitherto been demonstrated in humans and the pathophysiology of primary generalised epilepsy remains unknown. By means of PET and the benzodiazepine (BZ) ligand [11C]flumazenil it has been previously shown that the BZ receptor density is reduced in the epileptic foci of patients with partial epilepsy. In the present study the method was further developed and used in a comparative analysis of cortical, cerebellar, and subcortical BZ receptor binding in patients with primary generalised tonic and clonic seizures (n = 8), and healthy controls (n = 8). Patients with generalised seizures had an increased BZ receptor density in the cerebellar nuclei (p = 0.006) and decreased density in the thalamus (p = 0.003). No significant changes were seen in the cerebral and cerebellar cortex or in the basal ganglia. The observed alterations suggest that the gamma-amino-butyric acid (GABA)-BZ system may be affected in the cerebello-thalamocortical loop of patients with generalised epilepsy and indicate possible targets for selective pharmacological treatment. Images PMID:8021664

  17. Cell receptor and surface ligand density effects on dynamic states of adhering circulating tumor cells.

    PubMed

    Zheng, Xiangjun; Cheung, Luthur Siu-Lun; Schroeder, Joyce A; Jiang, Linan; Zohar, Yitshak

    2011-10-21

    Dynamic states of cancer cells moving under shear flow in an antibody-functionalized microchannel are investigated experimentally and theoretically. The cell motion is analyzed with the aid of a simplified physical model featuring a receptor-coated rigid sphere moving above a solid surface with immobilized ligands. The motion of the sphere is described by the Langevin equation accounting for the hydrodynamic loadings, gravitational force, receptor-ligand bindings, and thermal fluctuations; the receptor-ligand bonds are modeled as linear springs. Depending on the applied shear flow rate, three dynamic states of cell motion have been identified: (i) free motion, (ii) rolling adhesion, and (iii) firm adhesion. Of particular interest is the fraction of captured circulating tumor cells, defined as the capture ratio, via specific receptor-ligand bonds. The cell capture ratio decreases with increasing shear flow rate with a characteristic rate. Based on both experimental and theoretical results, the characteristic flow rate increases monotonically with increasing either cell-receptor or surface-ligand density within certain ranges. Utilizing it as a scaling parameter, flow-rate dependent capture ratios for various cell-surface combinations collapse onto a single curve described by an exponential formula.

  18. Aldosterone-reversible decrease in the density of renal peripheral benzodiazepine receptors in the rat after adrenalectomy

    SciTech Connect

    Basile, A.S.; Ostrowski, N.L.; Skolnick, P.

    1987-03-01

    A statistically significant decrease in the density of peripheral benzodiazepine receptors was observed in renal membranes of rats beginning 2 weeks after adrenalectomy when compared with sham-operated controls. This decrease in peripheral benzodiazepine receptor density was manifest as a decrease in the maximum binding of two ligands, (/sup 3/H)Ro 5-4864 and (/sup 3/H)PK 11195, without accompanying changes in their Kd for this site. Similar changes were not seen in another aldosterone-sensitive organ, the submandibular salivary gland. The decrease in peripheral benzodiazepine receptor density observed in adrenalectomized rat renal membranes was restored to control levels after 1 week of aldosterone administration using a dose (12.5 micrograms/kg/day) that had no effect on peripheral benzodiazepine receptor density in sham-operated animals. In contrast, dexamethasone administration (50 micrograms/kg/day, 1 week) had no effect on renal peripheral benzodiazepine receptor density when administered to either adrenalectomized or sham-operated rats. Further, adrenal demedullation had no effect on renal peripheral benzodiazepine receptor density or affinity. The decrease in peripheral benzodiazepine receptor density was localized to the renal cortex and the outer stripe of the medulla by gross dissection of renal slices and renal tissue section autoradiography. The specific effect of adrenalectomy on renal peripheral benzodiazepine receptor density, the lack of direct effect of aldosterone on (/sup 3/H) Ro 5-4864 binding and the localization of the change in peripheral benzodiazepine receptor density to the renal cortex and outer stripe suggest that these changes may reflect an adaptation of the renal nephron (possibly the distal convoluted tubule, intermediate tubule and/or the collecting duct) to the loss of mineralocorticoid hormones.

  19. Optimization of 2-phenylcyclopropylmethylamines as selective serotonin 2C receptor agonists and their evaluation as potential antipsychotic agents.

    PubMed

    Cheng, Jianjun; Giguère, Patrick M; Onajole, Oluseye K; Lv, Wei; Gaisin, Arsen; Gunosewoyo, Hendra; Schmerberg, Claire M; Pogorelov, Vladimir M; Rodriguiz, Ramona M; Vistoli, Giulio; Wetsel, William C; Roth, Bryan L; Kozikowski, Alan P

    2015-02-26

    The discovery of a new series of compounds that are potent, selective 5-HT2C receptor agonists is described herein as we continue our efforts to optimize the 2-phenylcyclopropylmethylamine scaffold. Modifications focused on the alkoxyl substituent present on the aromatic ring led to the identification of improved ligands with better potency at the 5-HT2C receptor and excellent selectivity against the 5-HT2A and 5-HT2B receptors. ADMET studies coupled with a behavioral test using the amphetamine-induced hyperactivity model identified four compounds possessing drug-like profiles and having antipsychotic properties. Compound (+)-16b, which displayed an EC50 of 4.2 nM at 5-HT2C, no activity at 5-HT2B, and an 89-fold selectivity against 5-HT2A, is one of the most potent and selective 5-HT2C agonists reported to date. The likely binding mode of this series of compounds to the 5-HT2C receptor was also investigated in a modeling study, using optimized models incorporating the structures of β2-adrenergic receptor and 5-HT2B receptor. PMID:25633969

  20. Chronic imipramine treatment reduces inhibitory properties of group II mGlu receptors without affecting their density or affinity.

    PubMed

    Pałucha, Agnieszka; Brański, Piotr; Kĺak, Kinga; Sowa, Magdalena

    2007-01-01

    An increasing body of evidence indicates an important role of the glutamatergic system in the pathophysiology of depression. Not only ionotropic but also metabotropic glutamate receptors (mGlu receptors) have been suggested to be involved in the mechanism of action of antidepressant drugs. Moreover, several mGlu receptor ligands possess a great antidepressant potential. Group II mGlu receptor antagonists have been shown to induce antidepressant-like effects in rodents. An influence of chronic antidepressant treatment on group II mGlu receptors has also been suggested. In our studies, we examined an influence of repeated (21-day) imipramine treatment on the density of group II mGlu receptors and affinity of mGlu2 and mGlu3 receptor radioligand [3H]-LY341495 for group II mGlu receptors in the rat brain hippocampus and frontal cortex. Moreover, we analyzed an influence of chronic imipramine administration on the ability of group II mGlu receptor agonist, 2R,4R-APDC, to inhibit forskolin-stimulated cAMP accumulation in the rat brain cortical slices. We found that inhibitory properties of group II mGlu receptors were diminished after chronic, but not acute imipramine administration. However, no changes in the density or affinity of the mGlu2 and mGlu3 receptor ligand for group II mGlu receptors were observed. PMID:18048952

  1. Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

    SciTech Connect

    Junker, L.H.; Davis, R.A. )

    1989-12-01

    The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of (14C)cholesterol from (2-14C)acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of (14C)cholesterol from (2-14C)acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis.

  2. Partial role of 5-HT2 and 5-HT3 receptors in the activity of antidepressants in the mouse forced swimming test.

    PubMed

    Redrobe, J P; Bourin, M

    1997-05-01

    The present study was designed to evaluate the roles of 5-HT2 and 5-HT3 receptors in the mouse forced swimming test, by using selective agonists and antagonists of 5-HT(2A/C) and 5-HT3 receptor sites. Agonists/antagonists and antidepressants were administered 45 min and 30 min, respectively, prior to testing. Pretreatment with (+/-)-2,5-dimethoxy-4-iodoamphetamine (DOI) (4 mg/kg, i.p.) or 2-methyl-5-HT (4 mg/kg, i.p.) had no effect on the anti-immobility effects of any antidepressant tested. Prior administration of ritanserin (4 mg/kg, i.p.) or ketanserin (8 mg/kg, i.p.), on the other hand, potentiated the effects of sub-active doses of imipramine (8 mg/kg, i.p.) and desipramine (16 mg/kg, i.p.) but not of maprotiline (8 mg/kg, i.p.), fluoxetine (16 mg/kg, i.p.), citalopram (16 mg/kg, i.p.) or fluvoxamine (8 mg/kg, i.p.). Pretreatment with ondansetron (1 X 10(-5) mg/kg, i.p.) enhanced the antidepressant-like effects of sub-active doses of the selective serotonin reuptake inhibitors. The results of the present study suggested that, in the forced swimming test, the selective serotonin reuptake inhibitors act partially through 5-HT3 receptor sites, whereas the tricyclic antidepressants exert effects at 5-HT(2A/C) receptor sites. Anti-immobility effects of the selective noradrenaline reuptake inhibitor, maprotiline, do not seem to be mediated by 5-HT(2A/C) or 5-HT3 receptor function.

  3. A discrepancy between platelet alpha 2-receptor density and functional circulatory changes in hypertensives

    SciTech Connect

    Mores, N.; Martire, M.; Pistritto, G.; Cardillo, C.; Folli, G. )

    1990-09-01

    To investigate whether differences exist in peripheral alpha 2-adrenoceptors between normotensive and hypertensive subjects, we determined platelet alpha 2-adrenoceptor density in 10 (7 males) untreated essential hypertensives (mean age of 51.1 years, range of 44-59 years) and in 10 age- and sex-matched normotensive controls. Moreover, in hypertensive patients, we examined the relationship between receptor density and cardiovascular reactivity to mental arithmetic, static handgrip, and bicycle exercise, to verify the hypothesis that alpha 2-adrenoceptors might play a role in modulation of hemodynamic response to sympathetic stimuli. alpha 2-Adrenoceptor density, as calculated by binding of (3H)yohimbine to platelets, was significantly higher in essential hypertensives (314.8 +/- 38.7 fmol/mg) than in normotensive subjects (213.6 +/- 34.7 fmol/mg) (p less than 0.05), whereas receptor affinity was similar in both groups (4.0 +/- 0.5 nM hypertensives, 4.3 +/- 0.5 nM normotensives; p greater than 0.05). Mental arithmetic increased mean arterial pressure (MAP) by 21.5% from basal values and heart rate (HR) by 13.2%. During isometric exercise, MAP increased by 38.1% and HR by 24.7%, while during bicycle ergometry, mean increases in MAP and HR from baseline were of 27.2 and 54.3%, respectively. No correlation was found between platelet alpha 2-adrenoceptor density and percent changes in MAP induced by all tests, or between adrenoceptors and absolute basal and peak MAP values. Our findings suggest that in hypertensive patients, peripheral alpha 2-adrenoceptors are increased with respect to matched normotensives, but these receptors seem not to be involved in the modulation of cardiovascular adaptation to enhanced sympathetic activity.

  4. The myeloperoxidase product hypochlorous acid generates irreversible high-density lipoprotein receptor inhibitors

    PubMed Central

    Binder, Veronika; Ljubojevic, Senka; Haybaeck, Johannes; Holzer, Michael; El-Gamal, Dalia; Schicho, Rudolf; Pieske, Burkert; Heinemann, Akos; Marsche, Gunther

    2014-01-01

    Objective Elevated levels of advanced oxidation protein products (AOPPs) have been described in several chronic inflammatory diseases, like chronic renal insufficiency, rheumatoid arthritis and atherosclerosis. Recent findings revealed that AOPPs are inhibitors of the major high-density lipoprotein (HDL) receptor, scavenger receptor class B, type 1 (SR-BI). Here we investigated what oxidation induced structural alterations convert plasma albumin into an HDL-receptor inhibitor. Approach and Results Exposure of albumin to the physiological oxidant, hypochlorous acid, generated high affinity SR-BI ligands. Protection of albumin lysine-residues prior exposure to hypochlorous acid as well as regeneration of N-chloramines after oxidation of albumin completely prevented binding of oxidized albumin to SR-BI, indicating that modification of albumin lysine-residues is required to generate SR-BI ligands. Of particular interest, N-chloramines within oxidized albumin promoted irreversible binding to SR-BI, resulting in permanent receptor blockade. We observed that the SR-BI inhibitory activity of albumin isolated from chronic kidney disease patients correlated with the content of the myeloperoxidase-specific oxidation product 3-chlorotyrosine and was associated with alterations in the composition of HDL. Conclusion Given that several potential atheroprotective activities of HDL are mediated by SR-BI, the present results raise the possibility that oxidized plasma albumin, through permanent SR-BI blockade, contributes to the pathophysiology of cardiovascular disease. PMID:23493288

  5. Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

    PubMed Central

    Landowski, Lila M.; Young, Kaylene M.

    2016-01-01

    The central nervous system (CNS) is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL) receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions. PMID:26949399

  6. Sleep deprivation increases A1 adenosine receptor density in the rat brain

    PubMed Central

    Elmenhorst, David; Basheer, Radhika; McCarley, Robert W.; Bauer, Andreas

    2013-01-01

    Adenosine, increasing after sleep deprivation and acting via the A1 adenosine receptor (A1AR), is likely a key factor in the homeostatic control of sleep. This study examines the impact of sleep deprivation on A1AR density in different parts of the rat brain with [3H]CPFPX autoradiography. Binding of [3H]CPFPX was significantly increased in parietal cortex (PAR) (7%), thalamus (11%) and caudate-putamen (9%) after 24 h of sleep deprivation compared to a control group with an undisturbed circadian sleep-wake rhythm. Sleep deprivation of 12 h changed receptor density regionally between −5% and +9% (motor cortex (M1), statistically significant) compared to the circadian control group. These results suggest cerebral A1ARs are involved in effects of sleep deprivation and the regulation of sleep. The increase of A1AR density could serve the purpose of not only maintaining the responsiveness to increased adenosine levels but also amplifying the effect of sleep deprivation and is in line with a sleep-induced homoeostatic reorganization at the synaptic level. PMID:19146833

  7. Ontogenic increase in PGE2 and PGF2 alpha receptor density in brain microvessels of pigs.

    PubMed Central

    Li, D. Y.; Varma, D. R.; Chemtob, S.

    1994-01-01

    1. The hypothesis that the relative vasoconstrictor ineffectiveness of prostaglandin E2 (PGE2) and PGF2 alpha on cerebral vessels of newborn pigs might be due to fewer receptors for these prostanoids was tested by comparing receptors for PGE2 (EP) and PGF2 alpha (FP) in cerebral microvessels from newborn and adult pigs. 2. Specific binding of [3H]-PGE2 and [3H]-PGF2 alpha to membranes prepared from brain microvessels showed that EP and FP receptor density (Bmax) in tissues from newborn animals was less than 50% of that determined in tissues from adults. By contrast, estimates of affinity (KD) were unchanged. 3. Specifically bound [3H]-PGE2 to brain microvessels from both the newborn and adult was displaced by AH 6809 (EP1-selective antagonist) by 80-90%, and only by approximately 30-35% by both 11-deoxy PGE1 (EP2/EP3 agonist) and M&B 28,767 (EP3 agonist); butaprost (EP2 agonist) was completely ineffective. 4. PGE2, 17-phenyl trinor PGE2 (EP1 agonist), PGF2 alpha and fenprostalene (PGF2 alpha analogue) caused significantly less increase in inositol 1,4,5-triphosphate (IP3) in brain microvessels from the newborn than in those from adult pigs. The stimulation of IP3 by PGE2 and 17-phenyl trinor PGE2 was almost completely inhibited by the EP1 antagonist, AH 6809. 5. PGE2, 11-deoxy PGE1 and M&B 28,767 produced small reduction of adenosine 3':5'-cyclic monophosphate (cyclic AMP) production in adult vessels but no effect in newborn tissues. 6. The lower density of EP and FP receptors in microvessels of newborn pigs compared to adults may explain the reduced ability of PGE2 and PGF2 alpha to stimulate production of IP3 in tissues from newborn animals.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8032662

  8. Molecular studies of pH-dependent ligand interactions with the low-density lipoprotein receptor.

    PubMed

    Yamamoto, Taichi; Chen, Hsuan-Chih; Guigard, Emmanuel; Kay, Cyril M; Ryan, Robert O

    2008-11-01

    The release of ligand from the low-density lipoprotein receptor (LDLR) has been postulated to involve a "histidine switch"-induced intramolecular rearrangement that discharges bound ligand. A recombinant soluble low-density lipoprotein receptor (sLDLR) was employed in ligand binding experiments with a fluorescently tagged variant apolipoprotein E N-terminal domain (apoE-NT). Binding was monitored as a function of fluorescence resonance energy transfer (FRET) from excited Trp residues in sLDLR to an extrinsic fluorophore covalently attached to Trp-null apoE3-NT. In binding experiments with wild-type (WT) sLDLR, FRET-dependent AEDANS fluorescence decreased as the pH was lowered. To investigate the role of His190, His562, and His586 in sLDLR in pH-dependent ligand binding and discharge, site-directed mutagenesis studies were performed. Compared to WT sLDLR, triple His --> Ala mutant sLDLR displayed attenuated pH-dependent ligand binding and a decreased level of ligand release as a function of low pH. When these His residues were substituted for Lys, the positively charged side chain of which does not ionize over this pH range, ligand binding was nearly abolished at all pH values. When sequential His to Lys mutants were examined, the evidence suggested that His562 and His586 function cooperatively. Whereas the sedimentation coefficient for WT sLDLR increased when the pH was reduced from 7 to 5, no such change occurred in the case of the triple Lys mutant receptor or a His562Lys/His586Lys double mutant receptor. The data support the existence of a cryptic, histidine side chain ionization-dependent alternative ligand that modulates ligand discharge via conformational reorganization.

  9. Development of 5-HT1A receptor radioligands to determine receptor density and changes in endogenous 5-HT.

    PubMed

    Jagoda, Elaine M; Lang, Lixin; Tokugawa, Joji; Simmons, Ashlie; Ma, Ying; Contoreggi, Carlo; Kiesewetter, Dale; Eckelman, William C

    2006-05-01

    [(18)F]FCWAY and [(18)F]FPWAY, analogues of the high affinity 5-HT(1A) receptor (5-HT(1A)R) antagonist WAY100635, were evaluated in rodents as potential radiopharmaceuticals for determining 5-HT(1A)R density and changes in receptor occupancy due to changes in endogenous serotonin (5-HT) levels. The in vivo hippocampus specific binding ratio [(hippocampus(uptake)/cerebellum(uptake))-1] of [(18)F]FPWAY was decreased to 32% of the ratio of [(18)F]FCWAY, indicating that [(18)F]FPWAY has lower affinity than [(18)F]FCWAY. The 5-HT(1A)R selectivity of [(18)F]FPWAY was confirmed using ex vivo autoradiography studies with 5-HT(1A)R knockout, heterozygous, and wildtype mice.Pre- or post-treatment of awake rodents in tissue dissection studies with paroxetine had no effect on hippocampal binding of [(18)F]FCWAY or [(18)F]FPWAY compared to controls, indicating neither tracer was sensitive to changes in endogenous 5-HT. In mouse ex vivo autoradiography studies in which awake mice were treated with fenfluramine following the [(18)F]FPWAY, a significant decrease was not observed in the hippocampus specific binding ratios. In rat dissection studies with fenfluramine administered following [(18)F]FPWAY or [(18)F]FBWAY ([(18)F]-MPPF) in awake or urethane-anesthetized rats, no significant differences in the specific binding ratios of the hippocampus were observed compared to their respective controls. [(18)F]FPWAY and [(18)F]FBWAY uptakes in all brain regions were increased variably in the anesthetized group (with the greatest increase in the hippocampus) vs. the awake group, but were decreased in the fenfluramine-treated anesthetized group vs. the anesthetized group. These data are best explained by changes in blood flow caused by urethane and fenfluramine, which varies from region to region in the brain. PMID:16440292

  10. Phagocytosis of aggregated lipoprotein by macrophages: Low density lipoprotein receptor-dependent foam-cell formation

    SciTech Connect

    Suits, A.G.; Chait, A.; Aviram, M.; Heinecke, J.W. )

    1989-04-01

    Low density lipoprotein (LDL) modified by incubation with phospholipase C (PLC-LDL) aggregates in solution and is rapidly taken up and degraded by human and mouse macrophages, producing foam cells in vitro. Human, mouse, and rabbit macrophages degraded {sup 125}I-labeled PLC-LDL ({sup 125}I-PLC-LDL) more rapidly than native {sup 125}I-labeled LDL ({sup 125}I-LDL), while nonphagocytic cells such as human fibroblasts and bovine aortic endothelial cells degraded {sup 125}I-PLC-LDL more slowly than {sup 125}I-LDL. This suggested the mechanism for internalization of PLC-LDL was phagocytosis. When examined by electron microscopy, mouse peritoneal macrophages appeared to be phagocytosing PLC-LDL. The uptake and degradation of {sup 125}I-PLC-LDL by human macrophages was inhibited >80% by the monoclonal antibody C7 (IgG2b) produced by hybridoma C7, which blocks the ligand binding domain of the LDL receptor. Similarly, methylation of {sup 125}I-LDL ({sup 125}I-MeLDL) prior to treatment with phospholipase C decreased its subsequent uptake and degradation by human macrophages by >90%. The uptake and degradation of phospholipase C-modified {sup 125}I-MeLDL by macrophages could be restored by incubation of the methylated lipoprotein with apoprotein E, a ligand recognized by the LDL receptor. These results indicate that macrophages internalize PLC-LDL by LDL receptor-dependent phagocytosis.

  11. Antibodies against low-density lipoprotein receptor-related protein 4 induce myasthenia gravis.

    PubMed

    Shen, Chengyong; Lu, Yisheng; Zhang, Bin; Figueiredo, Dwight; Bean, Jonathan; Jung, Jiung; Wu, Haitao; Barik, Arnab; Yin, Dong-Min; Xiong, Wen-Cheng; Mei, Lin

    2013-12-01

    Myasthenia gravis (MG) is the most common disorder affecting the neuromuscular junction (NMJ). MG is frequently caused by autoantibodies against acetylcholine receptor (AChR) and a kinase critical for NMJ formation, MuSK; however, a proportion of MG patients are double-negative for anti-AChR and anti-MuSK antibodies. Recent studies in these subjects have identified autoantibodies against low-density lipoprotein receptor-related protein 4 (LRP4), an agrin receptor also critical for NMJ formation. LRP4 autoantibodies have not previously been implicated in MG pathogenesis. Here we demonstrate that mice immunized with the extracellular domain of LRP4 generated anti-LRP4 antibodies and exhibited MG-associated symptoms, including muscle weakness, reduced compound muscle action potentials (CMAPs), and compromised neuromuscular transmission. Additionally, fragmented and distorted NMJs were evident at both the light microscopic and electron microscopic levels. We found that anti-LRP4 sera decreased cell surface LRP4 levels, inhibited agrin-induced MuSK activation and AChR clustering, and activated complements, revealing potential pathophysiological mechanisms. To further confirm the pathogenicity of LRP4 antibodies, we transferred IgGs purified from LRP4-immunized rabbits into naive mice and found that they exhibited MG-like symptoms, including reduced CMAP and impaired neuromuscular transmission. Together, these data demonstrate that LRP4 autoantibodies induce MG and that LRP4 contributes to NMJ maintenance in adulthood. PMID:24200689

  12. Multiple microvascular and astroglial 5-hydroxytryptamine receptor subtypes in human brain: molecular and pharmacologic characterization.

    PubMed

    Cohen, Z; Bouchelet, I; Olivier, A; Villemure, J G; Ball, R; Stanimirovic, D B; Hamel, E

    1999-08-01

    Physiologic and anatomic evidence suggest that 5-hydroxytryptamine (5-HT) neurons regulate local cerebral blood flow and blood-brain barrier permeability. To evaluate the possibility that some of these effects occur directly on the blood vessels, molecular and/or pharmacologic approaches were used to assess the presence of 5-HT receptors in human brain microvascular fractions, endothelial and smooth muscle cell cultures, as well as in astroglial cells which intimately associate with intraparenchymal blood vessels. Isolated microvessels and capillaries consistently expressed messages for the h5-HT1B, h5-HT1D, 5-HT1F, 5-HT2A but not 5-HT7 receptors. When their distribution within the vessel wall was studied in more detail, it was found that capillary endothelial cells exhibited mRNA for the h5-HT1D and for the 5-HT7 receptors whereas microvascular smooth muscle cells, in addition to h5-HT1D and 5-HT7, also showed polymerase chain reaction products for h5-HT1B receptors. Expression of 5-HT1F and 5-HT2A receptor mRNAs was never detected in any of the microvascular cell cultures. In contrast, messages for all 5-HT receptors tested were detected in human brain astrocytes with a predominance of the 5-HT2A and 5-HT7 subtypes. In all cultures, sumatriptan inhibited (35-58%, P < .05) the forskolin-stimulated production of cyclic AMP, an effect blocked by the 5-HT1B/1D receptor antagonists GR127935 and GR55562. In contrast, 5-carboxamidotryptamine induced strong increases (> or = 400%, P < .005) in basal cyclic AMP levels that were abolished by mesulergine, a nonselective 5-HT7 receptor antagonist. Only astroglial cells showed a ketanserin-sensitive increase (177%, P < .05) in IP3 formation when exposed to 5-HT. These results show that specific populations of functional 5-HT receptors are differentially distributed within the various cellular compartments of the human cortical microvascular bed, and that human brain astroglial cells are endowed with multiple 5-HT receptors

  13. Lipopolysaccharide Is Cleared from the Circulation by Hepatocytes via the Low Density Lipoprotein Receptor

    PubMed Central

    Topchiy, Elena; Cirstea, Mihai; Kong, HyeJin Julia; Boyd, John H.; Wang, Yingjin; Russell, James A.; Walley, Keith R.

    2016-01-01

    Sepsis is the leading cause of death in critically ill patients. While decreased Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) function improves clinical outcomes in murine and human sepsis, the mechanisms involved have not been fully elucidated. We tested the hypothesis that lipopolysaccharide (LPS), the major Gram-negative bacteria endotoxin, is cleared from the circulation by hepatocyte Low Density Lipoprotein Receptors (LDLR)—receptors downregulated by PCSK9. We directly visualized LPS uptake and found that LPS is rapidly taken up by hepatocytes into the cell periphery. Over the course of 4 hours LPS is transported towards the cell center. We next found that clearance of injected LPS from the blood was reduced substantially in Ldlr knockout (Ldlr-/-) mice compared to wild type controls and, simultaneously, hepatic uptake of LPS was also reduced in Ldlr-/- mice. Specifically examining the role of hepatocytes, we further found that primary hepatocytes isolated from Ldlr-/- mice had greatly decreased LPS uptake. In the HepG2 immortalized human hepatocyte cell line, LDLR silencing similarly resulted in decreased LPS uptake. PCSK9 treatment reduces LDLR density on hepatocytes and, therefore, was another independent strategy to test our hypothesis. Incubation with PCSK9 reduced LPS uptake by hepatocytes. Taken together, these findings demonstrate that hepatocytes clear LPS from the circulation via the LDLR and PCSK9 regulates LPS clearance from the circulation during sepsis by downregulation of hepatic LDLR. PMID:27171436

  14. Oxytocin receptor density is associated with male mating tactics and social monogamy.

    PubMed

    Ophir, Alexander G; Gessel, Ana; Zheng, Da-Jiang; Phelps, Steven M

    2012-03-01

    Despite its well-described role in female affiliation, the influence of oxytocin on male pairbonding is largely unknown. However, recent human studies indicate that this nonapeptide has a potent influence on male behaviors commonly associated with monogamy. Here we investigated the distribution of oxytocin receptors (OTR) throughout the forebrain of the socially monogamous male prairie vole (Microtus ochrogaster). Because males vary in both sexual and spatial fidelity, we explored the extent to which OTR predicted monogamous or non-monogamous patterns of space use, mating success and sexual fidelity in free-living males. We found that monogamous males expressed higher OTR density in the nucleus accumbens than non-monogamous males, a result that mirrors species differences in voles with different mating systems. OTR density in the posterior portion of the insula predicted mating success. Finally, OTR in the hippocampus and septohippocampal nucleus, which are nuclei associated with spatial memory, predicted patterns of space use and reproductive success within mating tactics. Our data highlight the importance of oxytocin receptor in neural structures associated with pairbonding and socio-spatial memory in male mating tactics. The role of memory in mating systems is often neglected, despite the fact that mating tactics impose an inherently spatial challenge for animals. Identifying mechanisms responsible for relating information about the social world with mechanisms mediating pairbonding and mating tactics is crucial to fully appreciate the suite of factors driving mating systems. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

  15. Oxytocin receptor density is associated with male mating tactics and social monogamy

    PubMed Central

    Ophir, Alexander G.; Gessel, Ana; Zheng, Da-Jiang; Phelps, Steven M.

    2012-01-01

    Despite its well-described role in female affiliation, the influence of oxytocin on male pairbonding is largely unknown. However, recent human studies indicate that this nonapeptide has a potent influence on male behaviors commonly associated with monogamy. Here we investigated the distribution of oxytocin receptors (OTR) throughout the forebrain of the socially monogamous male prairie vole (Microtus ochrogaster). Because males vary in both sexual and spatial fidelity, we explored the extent to which OTR predicted monogamous or non-monogamous patterns of space use, mating success and sexual fidelity in free-living males. We found that monogamous males expressed higher OTR density in the nucleus accumbens than non-monogamous males, a result that mirrors species differences in voles with different mating systems. OTR density in the posterior portion of the insula predicted mating success. Finally, OTR in the hippocampus and septohippocampal nucleus, which are nuclei associated with spatial memory, predicted patterns of space use and reproductive success within mating tactics. Our data highlight the importance of oxytocin receptor in neural structures associated with pairbonding and socio-spatial memory in male mating tactics. The role of memory in mating systems is often neglected, despite the fact that mating tactics impose an inherently spatial challenge for animals. Identifying mechanisms responsible for relating information about the social world with mechanisms mediating pairbonding and mating tactics is crucial to fully appreciate the suite of factors driving mating systems. PMID:22285648

  16. Dopamine D1, D2, D3 Receptors, Vesicular Monoamine Transporter Type-2 (VMAT2) and Dopamine Transporter (DAT) Densities in Aged Human Brain

    PubMed Central

    Sun, Jianjun; Xu, Jinbin; Cairns, Nigel J.; Perlmutter, Joel S.; Mach, Robert H.

    2012-01-01

    The dopamine D1, D2, D3 receptors, vesicular monoamine transporter type-2 (VMAT2), and dopamine transporter (DAT) densities were measured in 11 aged human brains (aged 77–107.8, mean: 91 years) by quantitative autoradiography. The density of D1 receptors, VMAT2, and DAT was measured using [3H]SCH23390, [3H]dihydrotetrabenazine, and [3H]WIN35428, respectively. The density of D2 and D3 receptors was calculated using the D3-preferring radioligand, [3H]WC-10 and the D2-preferring radioligand [3H]raclopride using a mathematical model developed previously by our group. Dopamine D1, D2, and D3 receptors are extensively distributed throughout striatum; the highest density of D3 receptors occurred in the nucleus accumbens (NAc). The density of the DAT is 10–20-fold lower than that of VMAT2 in striatal regions. Dopamine D3 receptor density exceeded D2 receptor densities in extrastriatal regions, and thalamus contained a high level of D3 receptors with negligible D2 receptors. The density of dopamine D1 linearly correlated with D3 receptor density in the thalamus. The density of the DAT was negligible in the extrastriatal regions whereas the VMAT2 was expressed in moderate density. D3 receptor and VMAT2 densities were in similar level between the aged human and aged rhesus brain samples, whereas aged human brain samples had lower range of densities of D1 and D2 receptors and DAT compared with the aged rhesus monkey brain. The differential density of D3 and D2 receptors in human brain will be useful in the interpretation of PET imaging studies in human subjects with existing radiotracers, and assist in the validation of newer PET radiotracers having a higher selectivity for dopamine D2 or D3 receptors. PMID:23185343

  17. Differences in adenosine A-1 and A-2 receptor density revealed by autoradiography in methylxanthine-sensitive and insensitive mice

    SciTech Connect

    Jarvis, M.F.; Williams, M.

    1988-07-01

    Two strains of inbred mice, CBA/J and SWR/J, have been identified which are, respectively, sensitive and insensitive to the behavioral and toxic effects of methylxanthines. Autoradiographic analyses of brain adenosine receptors were conducted with (/sup 3/H)CHA to label adenosine A-1 receptors and (/sup 3/H)NECA, in the presence of 50 nM CPA, to label adenosine A-2 receptors. For both mouse strains, adenosine A-1 receptors were most highly concentrated in the hippocampus and cerebellum whereas adenosine A-2 receptors were selectively localized in the striatum. CBA/J mice displayed a 30% greater density of adenosine A-1 receptors in the hippocampal CA-1 and CA-3 regions and in the cerebellum as compared to the SWR/J mice. The number of A-2 receptors (Bmax) was 40% greater in the striatum and olfactory tubercle of CBA/J as compared to SWR/J mice. No significant regional differences in A-1 or A-2 receptor affinities were observed between these inbred strains of mice. These results indicate that the differential sensitivity to methylxanthines between these mouse strains may reflect a genetically mediated difference in regional adenosine receptor densities.

  18. Studies of activated GPIIb/IIIa receptors on the luminal surface of adherent platelets. Paradoxical loss of luminal receptors when platelets adhere to high density fibrinogen.

    PubMed Central

    Coller, B S; Kutok, J L; Scudder, L E; Galanakis, D K; West, S M; Rudomen, G S; Springer, K T

    1993-01-01

    The accessibility of activated GPIIb/IIIa receptors on the luminal surface of platelets adherent to damaged blood vessels or atherosclerotic plaques is likely to play a crucial role in subsequent platelet recruitment. To define better the factors involved in this process, we developed a functional assay to assess the presence of activated, luminal GPIIb/IIIa receptors, based on their ability to bind erythrocytes containing a high density of covalently coupled RGD-containing peptides (thromboerythrocytes). Platelets readily adhered to wells coated with purified type I rat skin collagen and the adherent platelets bound a dense lawn of thromboerythrocytes. With fibrinogen-coated wells, platelet adhesion increased as the fibrinogen-coating concentration increased, reaching a plateau at about 11 micrograms/ml. Thromboerythrocyte binding to the platelets adherent to fibrinogen showed a paradoxical response, increasing at fibrinogen coating concentrations up to approximately 4-6 micrograms/ml and then dramatically decreasing at higher fibrinogen-coating concentrations. Scanning electron microscopy demonstrated that the morphology of platelets adherent to collagen was similar to that of platelets adherent to low density fibrinogen, with extensive filopodia formation and ruffling. In contrast, platelets adherent to high density fibrinogen showed a bland, flattened appearance. Immunogold staining of GPIIb/IIIa receptors demonstrated concentration of the receptors on the filopodia, and depletion of receptors on the flattened portion of the platelets. Thus, there is a paradoxical loss of accessible, activated GPIIb/IIIa receptors on the luminal surface of platelets adherent to high density fibrinogen. Two factors may contribute to this result: engagement of GPIIb/IIIa receptors with fibrinogen on the abluminal surface leading to the loss of luminal receptors, and loss of luminal filopodia that interact with thromboerythrocytes. These data provide insight into the differences

  19. Regulation of Rac1 activation by the low density lipoprotein receptor-related protein.

    PubMed

    Ma, Zhong; Thomas, Keena S; Webb, Donna J; Moravec, Radim; Salicioni, Ana Maria; Mars, Wendy M; Gonias, Steven L

    2002-12-23

    The low density lipoprotein receptor-related protein (LRP-1) binds and mediates the endocytosis of multiple ligands, transports the urokinase-type plasminogen activator receptor (uPAR) and other membrane proteins into endosomes, and binds intracellular adaptor proteins involved in cell signaling. In this paper, we show that in murine embryonic fibroblasts (MEFs) and L929 cells, LRP-1 functions as a major regulator of Rac1 activation, and that this activity depends on uPAR. LRP-1-deficient MEFs demonstrated increased Rac1 activation compared with LRP-1-expressing MEFs, and this property was reversed by expressing the VLDL receptor, a member of the same gene family as LRP-1, with overlapping ligand-binding specificity. Neutralizing the activity of LRP-1 with receptor-associated protein (RAP) increased Rac1 activation and cell migration in MEFs and L929 cells. The same parameters were unaffected by RAP in uPAR-/- MEFs, prepared from uPAR gene knockout embryos, and in uPAR-deficient LM-TK- cells. Untreated uPAR+/+ MEFs demonstrated substantially increased Rac1 activation compared with uPAR-/- MEFs. In addition to Rac1, LRP-1 suppressed activation of extracellular signal-regulated kinase (ERK) in MEFs; however, it was Rac1 (and not ERK) that was responsible for the effects of LRP-1 on MEF migration. Thus, LRP-1 regulates two signaling proteins in the same cell (Rac1 and ERK), both of which may impact on cell migration. In uPAR-negative cells, LRP-1 neutralization does not affect Rac1 activation, and other mechanisms by which LRP-1 may regulate cell migration are not unmasked.

  20. Serotonin 2A Receptors Differentially Contribute to Abuse-Related Effects of Cocaine and Cocaine-Induced Nigrostriatal and Mesolimbic Dopamine Overflow in Nonhuman Primates

    PubMed Central

    Murnane, Kevin S.; Winschel, Jake; Schmidt, Karl T.; Stewart, LaShaya M.; Rose, Samuel J.; Cheng, Kejun; Rice, Kenner C.

    2013-01-01

    Two of the most commonly used procedures to study the abuse-related effects of drugs in laboratory animals are intravenous drug self-administration and reinstatement of extinguished behavior previously maintained by drug delivery. Intravenous self-administration is widely accepted to model ongoing drug-taking behavior, whereas reinstatement procedures are accepted to model relapse to drug taking following abstinence. Previous studies indicate that 5-HT2A receptor antagonists attenuate the reinstatement of cocaine-maintained behavior but not cocaine self-administration in rodents. Although the abuse-related effects of cocaine have been closely linked to brain dopamine systems, no previous study has determined whether this dissociation is related to differential regulation of dopamine neurotransmission. To elucidate the neuropharmacological and neuroanatomical mechanisms underlying this phenomenon, we evaluated the effects of the selective 5-HT2A receptor antagonist M100907 on intravenous cocaine self-administration and drug- and cue-primed reinstatement in rhesus macaques (Macaca mulatta). In separate subjects, we evaluated the role of 5-HT2A receptors in cocaine-induced dopamine overflow in the nucleus accumbens (n = 4) and the caudate nucleus (n = 5) using in vivo microdialysis. Consistent with previous studies, M100907 (0.3 mg/kg, i.m.) significantly attenuated drug- and cue-induced reinstatement but had no significant effects on cocaine self-administration across a range of maintenance doses. Importantly, M100907 (0.3 mg/kg, i.m.) attenuated cocaine-induced (1.0 mg/kg, i.v.) dopamine overflow in the caudate nucleus but not in the nucleus accumbens. These data suggest that important abuse-related effects of cocaine are mediated by distinct striatal dopamine projection pathways. PMID:23946394

  1. Serotonin 2A receptors differentially contribute to abuse-related effects of cocaine and cocaine-induced nigrostriatal and mesolimbic dopamine overflow in nonhuman primates.

    PubMed

    Murnane, Kevin S; Winschel, Jake; Schmidt, Karl T; Stewart, LaShaya M; Rose, Samuel J; Cheng, Kejun; Rice, Kenner C; Howell, Leonard L

    2013-08-14

    Two of the most commonly used procedures to study the abuse-related effects of drugs in laboratory animals are intravenous drug self-administration and reinstatement of extinguished behavior previously maintained by drug delivery. Intravenous self-administration is widely accepted to model ongoing drug-taking behavior, whereas reinstatement procedures are accepted to model relapse to drug taking following abstinence. Previous studies indicate that 5-HT2A receptor antagonists attenuate the reinstatement of cocaine-maintained behavior but not cocaine self-administration in rodents. Although the abuse-related effects of cocaine have been closely linked to brain dopamine systems, no previous study has determined whether this dissociation is related to differential regulation of dopamine neurotransmission. To elucidate the neuropharmacological and neuroanatomical mechanisms underlying this phenomenon, we evaluated the effects of the selective 5-HT2A receptor antagonist M100907 on intravenous cocaine self-administration and drug- and cue-primed reinstatement in rhesus macaques (Macaca mulatta). In separate subjects, we evaluated the role of 5-HT2A receptors in cocaine-induced dopamine overflow in the nucleus accumbens (n = 4) and the caudate nucleus (n = 5) using in vivo microdialysis. Consistent with previous studies, M100907 (0.3 mg/kg, i.m.) significantly attenuated drug- and cue-induced reinstatement but had no significant effects on cocaine self-administration across a range of maintenance doses. Importantly, M100907 (0.3 mg/kg, i.m.) attenuated cocaine-induced (1.0 mg/kg, i.v.) dopamine overflow in the caudate nucleus but not in the nucleus accumbens. These data suggest that important abuse-related effects of cocaine are mediated by distinct striatal dopamine projection pathways. PMID:23946394

  2. Illuminating epidermal growth factor receptor densities on filopodia through plasmon coupling.

    PubMed

    Wang, Jing; Boriskina, Svetlana V; Wang, Hongyun; Reinhard, Björn M

    2011-08-23

    Filopodia have been hypothesized to act as remote sensors of the cell environment, but many details of the sensor function remain unclear. We investigated the distribution of the epidermal growth factor (EGF) receptor (EGFR) density on filopodia and on the dorsal cell membrane of A431 human epidermoid carcinoma cells using a nanoplasmonic enabled imaging tool. We targeted cell surface EGFR with 40 nm diameter Au nanoparticles (NPs) using a high affinity multivalent labeling strategy and determined relative NP binding affinities spatially resolved through plasmon coupling. Distance-dependent near-field interactions between the labels generated a NP density (ρ)-dependent spectral response that facilitated a spatial mapping of the EGFR density distribution on subcellular length scales in an optical microscope in solution. The measured ρ values were significantly higher on filopodia than on the cellular surface, which is indicative of an enrichment of EGFR on filopodia. A detailed characterization of the spatial distribution of the NP immunolabels through scanning electron microscopy (SEM) confirmed the findings of the all-optical plasmon coupling studies and provided additional structural details. The NPs exhibited a preferential association with the sides of the filopodia. We calibrated the ρ-dependent spectral response of the Au immunolabels through correlation of optical spectroscopy and SEM. The experimental dependence of the measured plasmon resonance wavelength (λ(res)) of the interacting immunolabels on ρ was well described by the fit λ(res) = 595.0 nm - 46.36 nm exp(-ρ/51.48) for ρ ≤ 476 NPs/μm(2). The performed correlated spectroscopic/SEM studies pave the way toward quantitative immunolabeling studies of EGFR and other important cell surface receptors in an optical microscope. PMID:21761914

  3. High-Density Lipoproteins Rescue Diabetes-Impaired Angiogenesis via Scavenger Receptor Class B Type I.

    PubMed

    Tan, Joanne T M; Prosser, Hamish C G; Dunn, Louise L; Vanags, Laura Z; Ridiandries, Anisyah; Tsatralis, Tania; Leece, Laura; Clayton, Zoë E; Yuen, Sui Ching G; Robertson, Stacy; Lam, Yuen Ting; Celermajer, David S; Ng, Martin K C; Bursill, Christina A

    2016-10-01

    Disordered neovascularization and impaired wound healing are important contributors to diabetic vascular complications. We recently showed that high-density lipoproteins (HDLs) enhance ischemia-mediated neovascularization, and mounting evidence suggests HDL have antidiabetic properties. We therefore hypothesized that HDL rescue diabetes-impaired neovascularization. Streptozotocin-induced diabetic mice had reduced blood flow recovery and neovessel formation in a hindlimb ischemia model compared with nondiabetic mice. Reconstituted HDL (rHDL) infusions in diabetic mice restored blood flow recovery and capillary density to nondiabetic levels. Topical rHDL application rescued diabetes-impaired wound closure, wound angiogenesis, and capillary density. In vitro, rHDL increased key mediators involved in hypoxia-inducible factor-1α (HIF-1α) stabilization, including the phosphoinositide 3-kinase/Akt pathway, Siah1, and Siah2, and suppressed the prolyl hydroxylases (PHD) 2 and PHD3. rHDL rescued high glucose-induced impairment of tubulogenesis and vascular endothelial growth factor (VEGF) A protein production, a finding associated with enhanced phosphorylation of proangiogenic mediators VEGF receptor 2 and endothelial nitric oxide synthase. Siah1/2 small interfering RNA knockdown confirmed the importance of HIF-1α stability in mediating rHDL action. Lentiviral short hairpin RNA knockdown of scavenger receptor class B type I (SR-BI) in vitro and SR-BI(-/-) diabetic mice in vivo attenuated rHDL rescue of diabetes-impaired angiogenesis, indicating a key role for SR-BI. These findings provide a greater understanding of the vascular biological effects of HDL, with potential therapeutic implications for diabetic vascular complications. PMID:27284113

  4. The antidepressant activity of inositol in the forced swim test involves 5-HT(2) receptors.

    PubMed

    Einat, H; Clenet, F; Shaldubina, A; Belmaker, R H; Bourin, M

    2001-01-01

    The effect of inositol as an antidepressant was previously demonstrated in both animal models of depression-like behavior and in clinical trials. Unlike most antidepressant drugs, inositol does not have a clear target in the synapse and was not demonstrated to alter monoamine levels in the brain. The present study attempted to draw a psychopharmacological profile of inositol's behavioral effects by exploring the interactions between the drug and specific receptor agonists and antagonists in the forced swim test. Rats received inositol treatment (or control) in combination with the serotonergic metabolism inhibitor PCPA or with the noradrenergic neurotoxin DSP-4. Results indicated that PCPA but not DSP-4 abolished the ability of inositol to cause a reduction in immobility time in the forced swim test. In mice, the specific 5-HT(2A)/5-HT(2C) antagonist ritanserin, but not the 5-HT(1A)/5-HT(1B)/beta adrenergic antagonist pindolol, abolished inositol's effect in the forced swim test. The 5-HT(2A)/5-HT(2C) agonist DOI and the 5-HT(1A) agonist 8-OH-DPAT did not have any significant effects on inositol's activity. The present data indicates that the antidepressant effect of inositol may involve 5-HT(2) receptors. It is thus possible that the effects of reuptake antidepressant drugs and the effects of inositol may have a common final pathway.

  5. Radixin regulates synaptic GABAA receptor density and is essential for reversal learning and short-term memory

    PubMed Central

    Hausrat, Torben J.; Muhia, Mary; Gerrow, Kimberly; Thomas, Philip; Hirdes, Wiebke; Tsukita, Sachiko; Heisler, Frank F.; Herich, Lena; Dubroqua, Sylvain; Breiden, Petra; Feldon, Joram; Schwarz, Jürgen R; Yee, Benjamin K.; Smart, Trevor G.; Triller, Antoine; Kneussel, Matthias

    2015-01-01

    Neurotransmitter receptor density is a major variable in regulating synaptic strength. Receptors rapidly exchange between synapses and intracellular storage pools through endocytic recycling. In addition, lateral diffusion and confinement exchanges surface membrane receptors between synaptic and extrasynaptic sites. However, the signals that regulate this transition are currently unknown. GABAA receptors containing α5-subunits (GABAAR-α5) concentrate extrasynaptically through radixin (Rdx)-mediated anchorage at the actin cytoskeleton. Here we report a novel mechanism that regulates adjustable plasma membrane receptor pools in the control of synaptic receptor density. RhoA/ROCK signalling regulates an activity-dependent Rdx phosphorylation switch that uncouples GABAAR-α5 from its extrasynaptic anchor, thereby enriching synaptic receptor numbers. Thus, the unphosphorylated form of Rdx alters mIPSCs. Rdx gene knockout impairs reversal learning and short-term memory, and Rdx phosphorylation in wild-type mice exhibits experience-dependent changes when exposed to novel environments. Our data suggest an additional mode of synaptic plasticity, in which extrasynaptic receptor reservoirs supply synaptic GABAARs. PMID:25891999

  6. Amount of stroma is associated with mammographic density and stromal expression of oestrogen receptor in normal breast tissues.

    PubMed

    Gabrielson, Marike; Chiesa, Flaminia; Paulsson, Janna; Strell, Carina; Behmer, Catharina; Rönnow, Katarina; Czene, Kamila; Östman, Arne; Hall, Per

    2016-07-01

    Following female sex and age, mammographic density is considered one of the strongest risk factors for breast cancer. Despite the association between mammographic density and breast cancer risk, little is known about the underlying histology and biological basis of breast density. To better understand the mechanisms behind mammographic density we assessed morphology, proliferation and hormone receptor status in relation to mammographic density in breast tissues from healthy women. Tissues were obtained from 2012-2013 by ultrasound-guided core needle biopsy from 160 women as part of the Karma (Karolinska mammography project for risk prediction for breast cancer) project. Mammograms were collected through routine mammography screening and mammographic density was calculated using STRATUS. The histological composition, epithelial and stromal proliferation status and hormone receptor status were assessed through immunohistochemical staining. Higher mammographic density was significantly associated with a greater proportion of stromal and epithelial tissue and a lower proportion of adipose tissue. Epithelial expression levels of Ki-67, oestrogen receptor (ER) and progesterone receptor (PR) were not associated with mammographic density. Epithelial Ki-67 was associated with a greater proportion of epithelial tissue, and epithelial PR was associated with a greater proportion of stromal and a lower proportion of adipose tissue. Epithelial ER was not associated with any tissues. In contrast, expression of ER in the stroma was significantly associated with a greater proportion of stroma, and negatively associated with the amount of adipose tissue. High mammographic density is associated with higher amount of stroma and epithelium and less amount of fat, but is not associated with a change in epithelial proliferation or receptor status. Increased expressions of both epithelial PR and stromal ER are associated with a greater proportion of stroma, suggesting hormonal involvement

  7. Hypercholesterolemia, low density lipoprotein receptor and proprotein convertase subtilisin/kexin-type 9

    PubMed Central

    Gu, Hong-mei; Zhang, Da-wei

    2015-01-01

    Abstract Atherosclerotic cardiovascular disease is the main cause of mortality and morbidity in the world. Plasma levels of low density lipoprotein cholesterol (LDL-C) are positively correlated with the risk of atherosclerosis. High plasma LDL concentrations in patients with hypercholesterolemia lead to build-up of LDL in the inner walls of the arteries, which becomes oxidized and promotes the formation of foam cells, consequently initiating atherosclerosis. Plasma LDL is mainly cleared through the LDL receptor (LDLR) pathway. Mutations in the LDLR cause familiar hypercholesterolemia and increase the risk of premature coronary heart disease. The expression of LDLR is regulated at the transcriptional level via the sterol regulatory element binding protein 2 (SREBP-2) and at the posttranslational levels mainly through proprotein convertase subtilisin/kexin-type 9 (PCSK9) and inducible degrader of the LDLR (IDOL). In this review, we summarize the latest advances in the studies of PCSK9. PMID:26445568

  8. Increased uptake of alpha-hydroxy aldehyde-modified low density lipoprotein by macrophage scavenger receptors.

    PubMed

    Kawamura, M; Heinecke, J W; Chait, A

    2000-07-01

    Reactive aldehydes can be formed during the oxidation of lipids, glucose, and amino acids and during the nonenzymatic glycation of proteins. Low density lipoprotein (LDL) modified with malondialdehyde are taken up by scavenger receptors on macrophages. In the current studies we determined whether alpha-hydroxy aldehydes also modify LDL to a form recognized by macrophage scavenger receptors. LDL modified by incubation with glycolaldehyde, glyceraldehyde, erythrose, arabinose, or glucose (alpha-hydroxy aldehydes that possess two, three, four, five, and six carbon atoms, respectively) exhibited decreased free amino groups and increased mobility on agarose gel electrophoresis. The lower the molecular weight of the aldehyde used for LDL modification, the more rapid and extensive was the derivatization of free amino groups. Approximately 50-75% of free lysine groups in LDL were modified after incubation with glyceraldehyde, glycolaldehyde, or erythrose for 24-48 h. Less extensive reductions in free amino groups were observed when LDL was incubated with arabinose or glucose, even at high concentration for up to 5 days. LDL modified with glycolaldehyde and glyceraldehyde labeled with (125)I was degraded more extensively by human monocyte-derived macrophages than was (125)I-labeled native LDL. Conversely, LDL modified with (125)I-labeled erythrose, arabinose, or glucose was degraded less rapidly than (125)I-labeled native LDL. Competition for the degradation of LDL modified with (125)I-labeled glyceraldehyde was nearly complete with acetyl-, glycolaldehyde-, and glyceraldehyde-modified LDL, fucoidin, and advanced glycation end product-modified bovine serum albumin, and absent with unlabeled native LDL. These results suggest that short-chain alpha-hydroxy aldehydes react with amino groups on LDL to yield moieties that are important determinants of recognition by macrophage scavenger receptors.

  9. Acceleration of atherogenesis by COX-1-dependent prostanoid formation in low density lipoprotein receptor knockout mice.

    PubMed

    Praticò, D; Tillmann, C; Zhang, Z B; Li, H; FitzGerald, G A

    2001-03-13

    The cyclooxygenase (COX) product, prostacyclin (PGI(2)), inhibits platelet activation and vascular smooth-muscle cell migration and proliferation. Biochemically selective inhibition of COX-2 reduces PGI(2) biosynthesis substantially in humans. Because deletion of the PGI(2) receptor accelerates atherogenesis in the fat-fed low density lipoprotein receptor knockout mouse, we wished to determine whether selective inhibition of COX-2 would accelerate atherogenesis in this model. To address this hypothesis, we used dosing with nimesulide, which inhibited COX-2 ex vivo, depressed urinary 2,3 dinor 6-keto PGF(1alpha) by approximately 60% but had no effect on thromboxane formation by platelets, which only express COX-1. By contrast, the isoform nonspecific inhibitor, indomethacin, suppressed platelet function and thromboxane formation ex vivo and in vivo, coincident with effects on PGI(2) biosynthesis indistinguishable from nimesulide. Indomethacin reduced the extent of atherosclerosis by 55 +/- 4%, whereas nimesulide failed to increase the rate of atherogenesis. Despite their divergent effects on atherogenesis, both drugs depressed two indices of systemic inflammation, soluble intracellular adhesion molecule-1, and monocyte chemoattractant protein-1 to a similar but incomplete degree. Neither drug altered serum lipids and the marked increase in vascular expression of COX-2 during atherogenesis. Accelerated progression of atherosclerosis is unlikely during chronic intake of specific COX-2 inhibitors. Furthermore, evidence that COX-1-derived prostanoids contribute to atherogenesis suggests that controlled evaluation of the effects of nonsteroidal anti-inflammatory drugs and/or aspirin on plaque progression in humans is timely.

  10. Involvement of second messengers in regulation of the low-density lipoprotein receptor gene

    SciTech Connect

    Auwerx, J.H. . ECHEM Labs.); Chait, A.; Wolfbauer, G.; Deeb, S.S. . Dept. of Medicine)

    1989-06-01

    Transcription of the low-density lipoprotein receptor (LDL-R) gene in the human monocytic leukemic cell line THP-1 and in the human hepatocarcinoma cell line Hep-G2 is regulated by second messengers of the diacylglycerol-protein kinase C (DAG-PKC), inositol 1,4,5-triphosphate-Ca/sup 2+/, and cyclic AMP pathways. Exogeneous phospholipase C (which releases DAG and inositol 1,4,5-triphosphate), PKC activators (phorbol esters and DAG), Ca/sup 2+/ ionophores, and a cyclic AMP analog all transiently induced accumulation of LDL-R mRNA. The effects of these three signal-transducing pathways were to a large extend additive. Furthermore, PKC stimulation effected an increase in LDL binding, which suggested that the increase in LDL-R mRNA resulted in an increase in functional cell surface receptor activity. These results suggest that uptake of cholesterol by these cells is under control of both intracellular cholesterol levels and external signals.

  11. Anionic phospholipids inhibit apolipoprotein E--low-density lipoprotein receptor interactions.

    PubMed

    Yamamoto, Taichi; Ryan, Robert O

    2007-03-16

    Apolipoprotein E (apoE) is a ligand for members of the low-density lipoprotein receptor (LDLR) family. Lipid-free apoE is not recognized by LDLR, yet interaction with lipid confers receptor recognition properties. Although lipid interaction is known to induce a conformational change in apoE, it is not known if the lipid composition of the resulting complex influences binding. Using reconstituted lipoprotein particles of apoE3 N-terminal (NT) domain and dimyristoylphosphatidylcholine (DMPC), maximal LDLR binding was observed at DMPC:apoE3-NT ratios >2.5:1 (w/w). ApoE3-NT lipid particles prepared with egg sphingomyelin were functional as LDLR ligands while complexes formed with the anionic phospholipids dimyristoylphosphatidylglycerol or dimyristoylphosphatidylserine (DMPS) were not. In the case of apoE3-NT, lipid particles comprised of a mixture of DMPC and DMPS, a DMPS concentration dependent inhibition of LDLR binding activity was observed. Thus, in addition to affecting apoE conformational status, the lipid composition of ligand particles can modulate LDLR binding activity.

  12. Myocardial blood flow and adenosine A2A receptor density in endurance athletes and untrained men

    PubMed Central

    Heinonen, Ilkka; Nesterov, Sergey V; Liukko, Kaisa; Kemppainen, Jukka; Någren, Kjell; Luotolahti, Matti; Virsu, Pauliina; Oikonen, Vesa; Nuutila, Pirjo; Kujala, Urho M; Kainulainen, Heikki; Boushel, Robert; Knuuti, Juhani; Kalliokoski, Kari K

    2008-01-01

    Previous human studies have shown divergent results concerning the effects of exercise training on myocardial blood flow (MBF) at rest or during adenosine-induced hyperaemia in humans. We studied whether these responses are related to alterations in adenosine A2A receptor (A2AR) density in the left-ventricular (LV) myocardium, size and work output of the athlete's heart, or to fitness level. MBF at baseline and during intravenous adenosine infusion, and A2AR density at baseline were measured using positron emission tomography, and by a novel A2AR tracer in 10 healthy male endurance athletes (ET) and 10 healthy untrained (UT) men. Structural LV parameters were measured with echocardiography. LV mass index was 71% higher in ET than UT (193 ± 18 g m−2versus 114 ± 13 g m−2, respectively). MBF per gram of tissue was significantly lower in the ET than UT at baseline, but this was only partly explained by reduced LV work load since MBF corrected for LV work was higher in ET than UT, as well as total MBF. The MBF during adenosine-induced hyperaemia was reduced in ET compared to UT, and the fitter the athlete was, the lower was adenosine-induced MBF. A2AR density was not different between the groups and was not coupled to resting or adenosine-mediated MBF. The novel findings of the present study show that the adaptations in the heart of highly trained endurance athletes lead to relative myocardial ‘overperfusion’ at rest. On the other hand hyperaemic perfusion is reduced, but is not explained by A2AR density. PMID:18772204

  13. The effect of the sigma-1 receptor selective compound LS-1-137 on the DOI-induced head twitch response in mice.

    PubMed

    Malik, Maninder; Rangel-Barajas, Claudia; Mach, Robert H; Luedtke, Robert R

    2016-09-01

    Several receptor mediated pathways have been shown to modulate the murine head twitch response (HTR). However, the role of sigma receptors in the murine (±)-2,5-dimethoxy-4-iodoamphetamine (DOI)-induced HTR has not been previously investigated. We examined the ability of LS-1-137, a novel sigma-1 vs. sigma-2 receptor selective phenylacetamide, to modulate the DOI-induced HTR in DBA/2J mice. We also assessed the in vivo efficacy of reference sigma-1 receptor antagonists and agonists PRE-084 and PPCC. The effect of the sigma-2 receptor selective antagonist RHM-1-86 was also examined. Rotarod analysis was performed to monitor motor coordination after LS-1-137 administration. Radioligand binding techniques were used to determine the affinity of LS-1-137 at 5-HT2A and 5-HT2C receptors. LS-1-137 and the sigma-1 receptor antagonists haloperidol and BD 1047 were able to attenuate a DOI-induced HTR, indicating that LS-1-137 was acting in vivo as a sigma-1 receptor antagonist. LS-1-137 did not compromise rotarod performance within a dose range capable of attenuating the effects of DOI. Radioligand binding studies indicate that LS-1-137 exhibits low affinity binding at both 5-HT2A and 5-HT2C receptors. Based upon the results from these and our previous studies, LS-1-137 is a neuroprotective agent that attenuates the murine DOI-induced HTR independent of activity at 5-HT2 receptor subtypes, D2-like dopamine receptors, sigma-2 receptors and NMDA receptors. LS-1-137 appears to act as a sigma-1 receptor antagonist to inhibit the DOI-induced HTR. Therefore, the DOI-induced HTR can be used to assess the in vivo efficacy of sigma-1 receptor selective compounds. PMID:27397487

  14. The effect of the sigma-1 receptor selective compound LS-1-137 on the DOI-induced head twitch response in mice.

    PubMed

    Malik, Maninder; Rangel-Barajas, Claudia; Mach, Robert H; Luedtke, Robert R

    2016-09-01

    Several receptor mediated pathways have been shown to modulate the murine head twitch response (HTR). However, the role of sigma receptors in the murine (±)-2,5-dimethoxy-4-iodoamphetamine (DOI)-induced HTR has not been previously investigated. We examined the ability of LS-1-137, a novel sigma-1 vs. sigma-2 receptor selective phenylacetamide, to modulate the DOI-induced HTR in DBA/2J mice. We also assessed the in vivo efficacy of reference sigma-1 receptor antagonists and agonists PRE-084 and PPCC. The effect of the sigma-2 receptor selective antagonist RHM-1-86 was also examined. Rotarod analysis was performed to monitor motor coordination after LS-1-137 administration. Radioligand binding techniques were used to determine the affinity of LS-1-137 at 5-HT2A and 5-HT2C receptors. LS-1-137 and the sigma-1 receptor antagonists haloperidol and BD 1047 were able to attenuate a DOI-induced HTR, indicating that LS-1-137 was acting in vivo as a sigma-1 receptor antagonist. LS-1-137 did not compromise rotarod performance within a dose range capable of attenuating the effects of DOI. Radioligand binding studies indicate that LS-1-137 exhibits low affinity binding at both 5-HT2A and 5-HT2C receptors. Based upon the results from these and our previous studies, LS-1-137 is a neuroprotective agent that attenuates the murine DOI-induced HTR independent of activity at 5-HT2 receptor subtypes, D2-like dopamine receptors, sigma-2 receptors and NMDA receptors. LS-1-137 appears to act as a sigma-1 receptor antagonist to inhibit the DOI-induced HTR. Therefore, the DOI-induced HTR can be used to assess the in vivo efficacy of sigma-1 receptor selective compounds.

  15. mRNA for low density lipoprotein receptor in brain and spinal cord of immature and mature rabbits

    SciTech Connect

    Hofmann, S.L.; Russell, D.W.; Goldstein, J.L.; Brown, M.S.

    1987-09-01

    Hybridization studies with (/sup 32/P)cDNA probes revealed detectable amounts of mRNA for the low density lipoprotein (LDL) receptor in the central nervous system (CNS) of rabbits. mRNA levels were highest in the medulla/pons and spinal cord, which were the most heavily myelinated regions that were studied. Lower, but detectable levels were present in cerebral cortex, hypothalamus, thalamus, midbrain, and cerebellum. In the medulla/pons and spinal cord, the levels of receptor mRNA were in a range comparable to that detected in the liver. The levels of receptor mRNA in whole brain were constant from 3 days of age to adulthood and, thus, did not vary in proportion to the rate of myelin synthesis. LDL receptor mRNA in the CNS was produced by the same gene that produced the liver and adrenal mRNA as revealed by the demonstration of a deletion in the neural mRNA of Watanabe-heritable hyperlipidemic (WHHL) rabbits identical to the deletion in the LDL receptor gene of these mutant animals. Using antibodies directed against the bovine LDL receptor, the authors showed that LDL receptor protein is present in the medulla/pons of adult cows. The cell types that express LDL receptors in the CNS and the functions of these receptors are unknown.

  16. Syntheses and pharmacological evaluation of two potent antagonists for dopamine D4 receptors: [11C]YM-50001 and N-[2-[4-(4-Chlorophenyl)-piperizin-1-yl]ethyl]-3-[11C]methoxybenzamide.

    PubMed

    Zhang, Ming-Rong; Haradahira, Terushi; Maeda, Jun; Okauchi, Takashi; Kawabe, Kouichi; Noguchi, Junko; Kida, Takayo; Suzuki, Kazutoshi; Suhara, Tetsuya

    2002-02-01

    Two benzamide derivatives as dopamine D4 receptor antagonists, YM-50001(4) and N- [2-[4-(4-chlorophenyl]piperizin-1-yl]ethyl]-3-methoxybenzamide (9), were labeled by positron-emitter (11C), and their pharmacological specificities to dopamine D4 receptors were examined by quantitative autoradiography and positron emission tomography (PET). Radiosyntheses were accomplished by O-methylation of corresponding phenol precursors (5 and 10) with [11C]CH3I followed by HPLC purifications. In vitro binding on rat brain slices showed different distribution patterns and pharmacological properties between the two radioligands. The [11C]4 showed the highest binding in the striatum, which was inhibited not only by 10 microM 4 but also by 10 microM raclopride, a selective dopamine D2 receptor antagonist. In contrast, [11C]9 showed the highest binding in the cerebral cortex, which was inhibited by several D4 receptor antagonists (9, RBI-254, L-745,870), but not by any other receptor ligands (D1/D5, D2/D3, 5-HT1A, 5-HT2A, sigma1 and alpha1) tested. In vivo brain distribution of [11C]9 in rat showed the highest uptake in the frontal cortex, a region that has a high density of D4 receptors. These results indicate that the pharmacological property of [11C]9 matches the rat brain D4 receptors, but that of [11C]4 rather appears to match the rat brain D2 receptors. The results for the benzamide [11C]9 prompted us to further evaluate its potential as a PET radioligand for D4 receptors by employing PET on monkey brain. Unfortunately, in contrast to rats, neither specific binding nor differences in regional uptake of radioactivity were observed in monkey brain after intravenous 11C]9 injection. Based on that specific activities of radioligands might be critical in mapping the neurotransmitter receptors if they are only faintly expressed in the brain, 11C]9 with an extremely high specific activity (1810 GBq/micromol) was used for PET study. However, the effort to determine the specific binding

  17. Tissue specific regulation of peripheral-type benzodiazepine receptor density after chemical sympathectomy

    SciTech Connect

    Basile, A.S.; Skolnick, P.

    1988-01-01

    The characteristics of (/sup 3/H)Ro 5-4864 binding to peripheral benzodiazepine receptors (PBR) in the central nervous system and peripheral tissues were examined after chemical sympathectomy with 6-hydroxydopamine (6-OHDA). One week after the intracisternal administration of 6-OHDA, the number of (/sup 3/H)Ro 5-4864 binding sites (Bmax) in the hypothalamus and striatum increased 41 and 50% respectively, concurrent with significant reductions in catecholamine content. An increase (34%) in the Bmax of (/sup 3/H)Ro 5-4864 to cardiac ventricle was observed one week after parenteral 6-OHDA administration. In contrast, the B/sub max/ of (/sup 3/H)Ro 5-4684 to pineal gland decreased 48% after 6-OHDA induced reduction in norepinephrine content. The Bmax values for (/sup 3/H)Ro 5-4864 binding to other tissues (including lung, kidney, spleen, cerebral cortex, cerebellum, hippocampus and olfactory bulbs) were unaffected by 6-OHDA administration. The density of pineal, but not cardiac PBR was also reduced after reserpine treatment, an effect reversed by isoproterenol administration. These findings demonstrate that alterations in sympathetic input may regulate the density of PBR in both the central nervous system and periphery in a tissue specific fashion. 33 references, 4 tables.

  18. Selective estrogen receptor modulators (SERMs) enhance neurogenesis and spine density following focal cerebral ischemia.

    PubMed

    Khan, Mohammad M; Wakade, Chandramohan; de Sevilla, Liesl; Brann, Darrell W

    2015-02-01

    Selective estrogen receptor modulators (SERMs) have been reported to enhance synaptic plasticity and improve cognitive performance in adult rats. SERMs have also been shown to induce neuroprotection against cerebral ischemia and other CNS insults. In this study, we sought to determine whether acute regulation of neurogenesis and spine remodeling could be a novel mechanism associated with neuroprotection induced by SERMs following cerebral ischemia. Toward this end, ovariectomized adult female rats were either implanted with pellets of 17β-estradiol (estrogen) or tamoxifen, or injected with raloxifene. After one week, cerebral ischemia was induced by the transient middle-cerebral artery occlusion (MCAO) method. Bromodeoxyuridine (BrdU) was injected to label dividing cells in brain. We analyzed neurogenesis and spine density at day-1 and day-5 post MCAO. In agreement with earlier findings, we observed a robust induction of neurogenesis in the ipsilateral subventricular zone (SVZ) of both the intact as well as ovariectomized female rats following MCAO. Interestingly, neurogenesis in the ipsilateral SVZ following ischemia was significantly higher in estrogen and raloxifene-treated animals compared to placebo-treated rats. In contrast, this enhancing effect on neurogenesis was not observed in tamoxifen-treated rats. Finally, both SERMs, as well as estrogen significantly reversed the spine density loss observed in the ischemic cortex at day-5 post ischemia. Taken, together these results reveal a profound structural remodeling potential of SERMs in the brain following cerebral ischemia. This article is part of a Special Issue entitled "Sex steroids and brain disorders".

  19. Dendritic spine density of prefrontal layer 6 pyramidal neurons in relation to apical dendrite sculpting by nicotinic acetylcholine receptors

    PubMed Central

    Kang, Lily; Tian, Michael K.; Bailey, Craig D. C.; Lambe, Evelyn K.

    2015-01-01

    Prefrontal layer 6 (L6) pyramidal neurons play an important role in the adult control of attention, facilitated by their strong activation by nicotinic acetylcholine receptors. These neurons in mouse association cortex are distinctive morphologically when compared to L6 neurons in primary cortical regions. Roughly equal proportions of the prefrontal L6 neurons have apical dendrites that are “long” (reaching to the pial surface) vs. “short” (terminating in the deep layers, as in primary cortical regions). This distinct prefrontal morphological pattern is established in the post-juvenile period and appears dependent on nicotinic receptors. Here, we examine dendritic spine densities in these two subgroups of prefrontal L6 pyramidal neurons under control conditions as well as after perturbation of nicotinic acetylcholine receptors. In control mice, the long neurons have significantly greater apical and basal dendritic spine density compared to the short neurons. Furthermore, manipulations of nicotinic receptors (chrna5 deletion or chronic developmental nicotine exposure) have distinct effects on these two subgroups of L6 neurons: apical spine density is significantly reduced in long neurons, and basal spine density is significantly increased in short neurons. These changes appear dependent on the α5 nicotinic subunit encoded by chrna5. Overall, the two subgroups of prefrontal L6 neurons appear positioned to integrate information either across cortex (long neurons) or within the deep layers (short neurons), and nicotinic perturbations differently alter spine density within each subgroup. PMID:26500498

  20. Breast density and parenchymal texture measures as potential risk factors for estrogen-receptor positive breast cancer

    NASA Astrophysics Data System (ADS)

    Keller, Brad M.; Chen, Jinbo; Conant, Emily F.; Kontos, Despina

    2014-03-01

    Accurate assessment of a woman's risk to develop specific subtypes of breast cancer is critical for appropriate utilization of chemopreventative measures, such as with tamoxifen in preventing estrogen-receptor positive breast cancer. In this context, we investigate quantitative measures of breast density and parenchymal texture, measures of glandular tissue content and tissue structure, as risk factors for estrogen-receptor positive (ER+) breast cancer. Mediolateral oblique (MLO) view digital mammograms of the contralateral breast from 106 women with unilateral invasive breast cancer were retrospectively analyzed. Breast density and parenchymal texture were analyzed via fully-automated software. Logistic regression with feature selection and was performed to predict ER+ versus ER- cancer status. A combined model considering all imaging measures extracted was compared to baseline models consisting of density-alone and texture-alone features. Area under the curve (AUC) of the receiver operating characteristic (ROC) and Delong's test were used to compare the models' discriminatory capacity for receptor status. The density-alone model had a discriminatory capacity of 0.62 AUC (p=0.05). The texture-alone model had a higher discriminatory capacity of 0.70 AUC (p=0.001), which was not significantly different compared to the density-alone model (p=0.37). In contrast the combined density-texture logistic regression model had a discriminatory capacity of 0.82 AUC (p<0.001), which was statistically significantly higher than both the density-alone (p<0.001) and texture-alone regression models (p=0.04). The combination of breast density and texture measures may have the potential to identify women specifically at risk for estrogen-receptor positive breast cancer and could be useful in triaging women into appropriate risk-reduction strategies.

  1. α7 Nicotinic Acetylcholine Receptors Occur at Postsynaptic Densities of AMPA Receptor-Positive and -Negative Excitatory Synapses in Rat Sensory Cortex

    PubMed Central

    Levy, Robert B.; Aoki, Chiye

    2010-01-01

    NMDA receptor (NMDAR) activation requires concurrent membrane depolarization, and glutamatergic synapses lacking AMPA receptors (AMPARs) are often considered “silent” in the absence of another source of membrane depolarization. During the second postnatal week, NMDA currents can be enhanced in rat auditory cortex through activation of the α7 nicotinic acetylcholine receptor (α7nAChR). Electrophysiological results support a mainly presynaptic role for α7nAChR at these synapses. However, immunocytochemical evidence that α7nAChR is prevalent at postsynaptic sites of glutamatergic synapses in hippocampus and neocortex, along with emerging electrophysiological evidence for postsynaptic nicotinic currents in neocortex and hippocampus, has prompted speculation that α7nAChR allows for activation of NMDAR postsynaptically at synapses lacking AMPAR. Here we used dual immunolabeling and electron microscopy to examine the distribution of α7nAChR relative to AMPAR (GluR1, GluR2, and GluR3 subunits combined) at excitatory synapses in somatosensory cortex of adult and 1-week-old rats. α7nAChR occurred discretely over most of the thick postsynaptic densities in all cortical layers of both age groups. AMPAR immunoreactivity was also detectable at most synapses; its distribution was independent of that of α7nAChR. In both age groups, approximately one-quarter of asymmetrical synapses were α7nAChR positive and AMPAR negative. The variability of postsynaptic α7nAChR labeling density was greater at postnatal day (PD) 7 than in adulthood, and PD 7 neuropil contained a subset of small AMPA receptor-negative synapses with a high density of α7nAChR immunoreactivity. These observations support the idea that acetylcholine receptors can aid in activating glutamatergic synapses and work together with AMPA receptors to mediate postsynaptic excitation throughout life. PMID:12077196

  2. Low-Density Lipoprotein Receptor-Related Protein-1 Protects Against Hepatic Insulin Resistance and Hepatic Steatosis.

    PubMed

    Ding, Yinyuan; Xian, Xunde; Holland, William L; Tsai, Shirling; Herz, Joachim

    2016-05-01

    Low-density lipoprotein receptor-related protein-1 (LRP1) is a multifunctional uptake receptor for chylomicron remnants in the liver. In vascular smooth muscle cells LRP1 controls reverse cholesterol transport through platelet-derived growth factor receptor β (PDGFR-β) trafficking and tyrosine kinase activity. Here we show that LRP1 regulates hepatic energy homeostasis by integrating insulin signaling with lipid uptake and secretion. Somatic inactivation of LRP1 in the liver (hLRP1KO) predisposes to diet-induced insulin resistance with dyslipidemia and non-alcoholic hepatic steatosis. On a high-fat diet, hLRP1KO mice develop a severe Metabolic Syndrome secondary to hepatic insulin resistance, reduced expression of insulin receptors on the hepatocyte surface and decreased glucose transporter 2 (GLUT2) translocation. While LRP1 is also required for efficient cell surface insulin receptor expression in the absence of exogenous lipids, this latent state of insulin resistance is unmasked by exposure to fatty acids. This further impairs insulin receptor trafficking and results in increased hepatic lipogenesis, impaired fatty acid oxidation and reduced very low density lipoprotein (VLDL) triglyceride secretion. PMID:27322467

  3. Serotonin1A receptors in the pathophysiology of schizophrenia: development of novel cognition-enhancing therapeutics.

    PubMed

    Sumiyoshi, Tomiki; Bubenikova-Valesova, Vera; Horacek, Jiri; Bert, Bettina

    2008-10-01

    Serotonin (5-HT) receptors have been suggested to play key roles in psychosis, cognition, and mood via influence on neurotransmitters, synaptic integrity, and neural plasticity. Specifically, genetic evidence indicates that 5-HT(1A), 5-HT(2A), and 5-HT(2C) receptor single-nucleotide polymorphisms (SNPs) are related to psychotic symptoms, cognitive disturbances, and treatment response in schizophrenia. Data from animal research suggest the role of 5-HT in cognition via its influence on dopaminergic, cholinergic, glutamatergic, and GABAergic function. This article provides up-to-date findings on the role of 5-HT receptors in endophenotypic variations in schizophrenia and the development of newer cognition-enhancing medications, based on basic science and clinical evidence. Imaging genetics studies on associations of polymorphisms of several 5-HT receptor subtypes with brain structure, function, and metabolism suggest a role for the prefrontal cortex and the parahippocampal gyrus in cognitive impairments of schizophrenia. Data from animal experiments to determine the effect of agonists/antagonists at 5-HT(1A), 5-HT(2A), and 5-HT(2C) receptors on behavioral performance in animal models of schizophrenia based on the glutamatergic hypothesis provide useful information. For this purpose, standard as well as novel cognitive tasks provide a measure of memory/information processing and social interaction. In order to scrutinize mixed evidence for the ability of 5-HT(1A) agonists/antagonists to improve cognition, behavioral data in various paradigms from transgenic mice overexpressing 5-HT(1A) receptors provide valuable insights. Clinical trials reporting the advantage of 5-HT(1A) partial agonists add to efforts to shape pharmacologic perspectives concerning cognitive enhancement in schizophrenia by developing novel compounds acting on 5-HT receptors. Overall, these lines of evidence from translational research will facilitate the development of newer pharmacologic strategies

  4. Genetic influences on bone density: Physiological correlates of vitamin D receptor gene alleles in premonopausal women

    SciTech Connect

    Howard, G.; Nguyen, T.; Morrison, N.

    1995-09-01

    Common vitamin D receptor (VDR) gene alleles have recently been shown to contribute to the genetic variability in bone mass and bone turnover; however, the physiological mechanisms involved are unknown. To examine this, the response to 7 days of 2 {mu}g oral 1,25-dihydroxyvitamin D[1,25-(OH){sub 2}D] (calcitrol) stimulation was assessed in 21 premenopausal women, homozygous for one or other of the common VDR alleles (bb, N = 11; BB, n = 10). Indices of bone turnover and calcium homeostasis were measured during 2 weeks. Baseline osteocalcin, 1,25-(OH){sub 2}D, type I collagen carboxyterminal telopeptide, and inorganic phosphate levels were significantly higher and spinal bone mineral density was significantly lower in the BB allelic group. After calcitrol administration, similar levels of 1,25-(OH){sub 2}D were attained throughout the study in both genotypic groups. The increase in serum osteocalcin levels in the BB group was significantly less than that in the bb group (11% vs. 32%, P = 0.01). The genotype-related baseline difference in osteocalcin levels was not apparent at the similar serum 1,25-(OH){sub 2}D levels. By contrast, the baseline differences in phosphate and type I collagen carboxyterminal telopeptide persisted throughout the study. Serum ionized calcium levels did not differ between genotypes, nor did it move out of normal range values. However, parathyroid hormone was less suppressed in the low bone density group (38% vs. 11%, P = 0.01). These data indicate that the VDR alleles are associated with differences in the vitamin D endocrine system and may have important implications in relation to the pathophysiology of osteoporosis. 35 refs., 2 figs., 1 tab.

  5. The low-density lipoprotein receptor-related protein 1 and amyloid-β clearance in Alzheimer’s disease

    PubMed Central

    Kanekiyo, Takahisa; Bu, Guojun

    2014-01-01

    Accumulation and aggregation of amyloid-β (Aβ) peptides in the brain trigger the development of progressive neurodegeneration and dementia associated with Alzheimer’s disease (AD). Perturbation in Aβ clearance, rather than Aβ production, is likely the cause of sporadic, late-onset AD, which accounts for the majority of AD cases. Since cellular uptake and subsequent degradation constitute a major Aβ clearance pathway, the receptor-mediated endocytosis of Aβ has been intensely investigated. Among Aβ receptors, the low-density lipoprotein receptor-related protein 1 (LRP1) is one of the most studied receptors. LRP1 is a large endocytic receptor for more than 40 ligands, including apolipoprotein E, α2-macroglobulin and Aβ. Emerging in vitro and in vivo evidence demonstrates that LRP1 is critically involved in brain Aβ clearance. LRP1 is highly expressed in a variety of cell types in the brain including neurons, vascular cells and glial cells, where LRP1 functions to maintain brain homeostasis and control Aβ metabolism. LRP1-mediated endocytosis regulates cellular Aβ uptake by binding to Aβ either directly or indirectly through its co-receptors or ligands. Furthermore, LRP1 regulates several signaling pathways, which also likely influences Aβ endocytic pathways. In this review, we discuss how LRP1 regulates the brain Aβ clearance and how this unique endocytic receptor participates in AD pathogenesis. Understanding of the mechanisms underlying LRP1-mediated Aβ clearance should enable the rational design of novel diagnostic and therapeutic strategies for AD. PMID:24904407

  6. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein.

    PubMed

    Thakkar, Shraddha; Wang, Xianwei; Khaidakov, Magomed; Dai, Yao; Gokulan, Kuppan; Mehta, Jawahar L; Varughese, Kottayil I

    2015-01-01

    Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential. PMID:26578342

  7. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein.

    PubMed

    Thakkar, Shraddha; Wang, Xianwei; Khaidakov, Magomed; Dai, Yao; Gokulan, Kuppan; Mehta, Jawahar L; Varughese, Kottayil I

    2015-11-18

    Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential.

  8. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein

    NASA Astrophysics Data System (ADS)

    Thakkar, Shraddha; Wang, Xianwei; Khaidakov, Magomed; Dai, Yao; Gokulan, Kuppan; Mehta, Jawahar L.; Varughese, Kottayil I.

    2015-11-01

    Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential.

  9. Functional Differences of Very-Low-Density Lipoprotein Receptor Splice Variants in Regulating Wnt Signaling

    PubMed Central

    Chen, Qian; Takahashi, Yusuke; Oka, Kazuhiro

    2016-01-01

    The very-low-density lipoprotein receptor (VLDLR) negatively regulates Wnt signaling. VLDLR has two major alternative splice variants, VLDLRI and VLDLRII, but their biological significance and distinction are unknown. Here we found that most tissues expressed both VLDLRI and VLDLRII, while the retina expressed only VLDLRII. The shed soluble VLDLR extracellular domain (sVLDLR-N) was detected in the conditioned medium of retinal pigment epithelial cells, interphotoreceptor matrix, and mouse plasma, indicating that ectodomain shedding of VLDLR occurs endogenously. VLDLRII displayed a higher ectodomain shedding rate and a more potent inhibitory effect on Wnt signaling than VLDLRI in vitro and in vivo. O-glycosylation, which is present in VLDLRI but not VLDLRII, determined the differential ectodomain shedding rates. Moreover, the release of sVLDLR-N was inhibited by a metalloproteinase inhibitor, TAPI-1, while it was promoted by phorbol 12-myristate 13-acetate (PMA). In addition, sVLDLR-N shedding was suppressed under hypoxia. Further, plasma levels of sVLDLR-N were reduced in both type 1 and type 2 diabetic mouse models. We concluded that VLDLRI and VLDLRII had differential roles in regulating Wnt signaling and that decreased plasma levels of sVLDLR-N may contribute to Wnt signaling activation in diabetic complications. Our study reveals a novel mechanism for intercellular regulation of Wnt signaling through VLDLR ectodomain shedding. PMID:27528615

  10. Insight into the Binding Mode of Agonists of the Nicotinic Acetylcholine Receptor from Calculated Electron Densities

    PubMed Central

    Beck, Michael E; Gutbrod, Oliver; Matthiesen, Svend

    2015-01-01

    Insect nicotinic acetylcholine receptors (nAChRs) are among the most prominent and most economically important insecticide targets. Thus, an understanding of the modes of binding of respective agonists is important for the design of specific compounds with favorable vertebrate profiles. In the case of nAChRs, the lack of available high-resolution X-ray structures leaves theoretical considerations as the only viable option. Starting from classical homology and docking approaches, binding mode hypotheses are created for five agonists of the nAChR, covering insecticides in the main group 4 of the Insecticide Resistance Action Committee (IRAC) mode of action (MoA) classification, namely, neonicotinoids, nicotine, sulfoxaflor, and butenolides. To better understand these binding modes, the topologies of calculated electron densities of small-model systems are analyzed in the framework of the quantum theory of atoms in molecules. The theoretically obtained modes of binding are very much in line with the biology-driven IRAC MoA classification of the investigated ligands. PMID:26175091

  11. Polymorphism of the low-density lipoprotein receptor-related protein 5 gene and fracture risk.

    PubMed

    Wang, Chao; Zhang, Gang; Gu, Mingyong; Zhou, Zhenyu; Cao, Xuecheng

    2014-01-01

    Several molecular epidemiological studies have been conducted to examine the association between low-density lipoprotein receptor-related proteins (LRP5) Ala1330Val polymorphism and fracture; however, the conclusions remained controversial. We therefore performed an extensive meta-analysis on 10 published studies with 184479 subjects. Electronic databases, including PubMed, Excerpta Medica Database (EMBASE), Cochrane, Elsevier Science Direct and China National Knowledge Infrastructure (CNKI) databases were searched. Summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using random-effects models. LRP5 Ala1330Val polymorphism was associated with a significantly increased risk of fracture (OR = 1.10; 95% CI, 1.06-1.14; I(2) = 29%). We also found that this polymorphism increased fracture risk in Caucasians. In the subgroup analysis according to gender, women was significantly associated with risk of fracture. In the subgroup analysis by type of fracture, LRP5 Ala1330Val polymorphism showed increased osteoporotic fracture risk. In conclusion, this meta-analysis suggested that an increased risk of fracture was associated with the LRP5 Ala1330Val polymorphism.

  12. Expression of the very low-density lipoprotein receptor (VLDL-r), an apolipoprotein-E receptor, in the central nervous system and in Alzheimer`s disease

    SciTech Connect

    Christie, R.H.; Chung, Haeyong; Rebeck, G.W.; Hyman, B.T.

    1996-04-01

    The very low density lipoprotein receptor (VLDL-r) is a cell-surface molecule specialized for the internalization of multiple diverse ligands, including apolipoprotein E (apoE)-containing lipoprotein particles, via clathrin-coated pits. Its structure is similar to the low-density lipoprotein receptor (LDL-r), although the two have substantially different systemic distributions and regulatory pathways. The present work examines the distribution of VLDL-r in the central nervous system (CNS) and in relation to senile plaques in Alzheimer disease (AD). VLDL-r is present on resting and activated microglia, particularly those associated with senile plaques (SPs). VLDL-r immunoreactivity is also found in cortical neurons. Two exons of VLDL-r mRNA are differentially spliced in the mature receptor mRNA. One set of splice forms gives rise to receptors containing (or lacking) an extracellular O-linked glycosylation domain near the transmembrane portion of the molecule. The other set of splice forms appears to be brain-specific, and is responsible for the presence or absence of one of the cysteine-rich repeat regions in the binding region of the molecule. Ratios of the receptor variants generated from these splice forms do not differ substantially across different cortical areas or in AD. We hypothesize that VLDL-r might contribute to metabolism of apoE and apoE/A{beta} complexes in the brain. Further characterization of apoE receptors in Alzheimer brain may help lay the groundwork for understanding the role of apoE in the CNS and in the pathophysiology of AD. 43 refs., 5 figs.

  13. Higher density of serotonin-1A receptors in the hippocampus and cerebral cortex of alcohol-preferring P rats

    SciTech Connect

    Wong, D.T.; Threlkeld, P.G. ); Lumeng, L.; Li, Ting-Kai )

    1990-01-01

    Saturable ({sup 3}H)-80HDPAT binding to 5HT-1A receptors in membranes prepared from hippocampus and frontal cerebral cortex of alcohol-preferring (P) rats and of alcohol-nonpreferring (NP) rats has been compared. The B{sub max} values or densities of recognition sites for 5HT-1A receptors in both brain areas of the P rats are 38 and 44 percent lower in the P rats than in the NP rats. The corresponding K{sub D} values are 38 and 44 percent lower in the P rats than in the NP rats, indicating higher affinities of the recognition sites for the 5HT-1A receptors in hippocampus and cerebral cortex of the P rats. These findings indicate either an enrichment of 5HT-1A receptor density during selective breeding for alcohol preference or an upregulation of 5HT-1A receptors of 5HT found in these brain areas of P rats as compared with the NP rats.

  14. Identification of the lectin-like receptor for oxidized low-density lipoprotein in human macrophages and its potential role as a scavenger receptor.

    PubMed Central

    Yoshida, H; Kondratenko, N; Green, S; Steinberg, D; Quehenberger, O

    1998-01-01

    A new receptor for oxidized low-density lipoprotein (LDL), lectin-like oxidized LDL receptor-1 (LOX-1), has recently been cloned from bovine endothelial cells and human lung. A limited tissue-distribution study suggested that the protein was mainly produced by the vascular endothelium. In the present study we demonstrate that LOX-1 is also expressed in macrophages, where it may function as a scavenger receptor. LOX-1 was not detected in undifferentiated THP-1 cells or in freshly isolated human blood monocytes. However, mature human monocyte-derived macrophages and differentiated THP-1 cells showed high levels of LOX-1 transcripts. Consistent with these results, immunofluorescence staining and FACS analysis demonstrated that LOX-1 protein is expressed on the plasma membrane of macrophages. Western-blot analysis of membranes from macrophages (but not those from monocytes) identified a single band, with an apparent molecular mass of about 40 kDa, that displayed oxidized LDL-binding activity. These results suggest that differentiation induces the expression of LOX-1 in macrophages, where it may play a role as a scavenger receptor and/or a receptor for oxidized LDL. PMID:9693095

  15. Assessment of dopamine receptor densities in the human brain with carbon-11-labeled N-methylspiperone

    SciTech Connect

    Wagner, H.N. Jr.; Burns, H.D.; Dannals, R.F.; Wong, D.F.; Langstroem, B.; Duelfer, T.; Frost, J.J.; Ravert, H.T.; Links, J.M.; Rosenbloom, S.B.

    1984-01-01

    We describe the use of carbon-11-labeled 3-N-methylspiperone, a ligand that preferentially binds to dopamine receptors in vivo, to image the receptors by positron emission tomography scanning in baboons and, for the first time, in a human. The method has now been used in 58 humans for noninvasive assessment of the state of brain dopamine receptors under normal and pathological conditions.

  16. Vitamin D receptor alleles and bone mineral density in a normal premenopausal Brazilian female population.

    PubMed

    Lazaretti-Castro, M; Duarte-de-Oliveira, M A; Russo, E M; Vieira, J G

    1997-08-01

    Studies on the association between vitamin D receptor (VDR) polymorphism and bone mineral density (BMD) in different populations have produced conflicting results probably due to ethnic differences in the populations studied. The Brazilian population is characterized by a very broad genetic background and a high degree of miscegenation. Of an initial group of 164, we studied 127 women from the city of São Paulo, aged 20 to 47 years (median, 31 years), with normal menses, a normal diet and no history of diseases or use of any medication that could alter BMD. VDR genotype was assessed by PCR amplification followed by BsmI digestion of DNA isolated from peripheral leukocytes. BMD was measured using dual energy X-ray absorptiometry (Lunar DPX) at the lumbar site (L2-L4) and femoral neck. Most of the women (77.6%) were considered to be of predominantly European ancestry (20.6% of them reported also native American ancestry), 12.8% were of African-Brazilian ancestry and 9.6% of Asian ancestry, 41.0% (52) were classified as bb, 48.8% (62) as Bb and 10.2% (13) as BB. The BB, Bb and bb groups did not differ in age, height, weight, body mass index or age at menarche. Lumbar spine BMD was significantly higher in the bb group (1.22 +/- 0.16 g/cm2) than in the BB group (1.08 +/- 0.14; P < 0.05), and the Bb group presented an intermediate value (1.17 +/- 0.15). Femoral neck BMD was higher in the bb group (0.99 +/- 0.11 g/cm2) compared to Bb (0.93 +/- 0.12) and BB (0.90 +/- 0.09) (P < 0.05). These data indicate that there is a significant correlation between the VDR BsmI genotype and BMD in healthy Brazilian premenopausal females. PMID:9361720

  17. Lectin-like Oxidized Low-Density Lipoprotein (LDL) Receptor (LOX-1): A Chameleon Receptor for Oxidized LDL.

    PubMed

    Zeya, Bushra; Arjuman, Albina; Chandra, Nimai Chand

    2016-08-16

    LOX-1, one of the main receptors for oxLDL, is found mainly on the surface of endothelial cells. It is a multifacet 52 kDa type II transmembrane protein that structurally belongs to the C-type lectin family. It exists with short intracellular N-terminal and long extracellular C-terminal hydrophilic domains separated by a hydrophobic domain of 26 amino acids. LOX-1 acts like a bifunctional receptor either showing pro-atherogenicity by activating the NFκB-mediated down signaling cascade for gene activation of pro-inflammatory molecules or playing an atheroprotective agent by receptor-mediated uptake of oxLDL in the presence of an anti-inflammatory molecule like IL-10. Mildly, moderately, and highly oxidized LDL show their characteristic features upon LOX-1 activation and its ligand binding indenture. The polymorphic LOX-1 genes are intensively associated with increased susceptibility to myocardial diseases. The splicing variant LOX IN dimerizes with the native form of LOX-1 and protects cells from damage by oxidized LDL. In the developing field of regenerating medicine, LOX-1 is a potential target for therapeutic intervention.

  18. Lectin-like Oxidized Low-Density Lipoprotein (LDL) Receptor (LOX-1): A Chameleon Receptor for Oxidized LDL.

    PubMed

    Zeya, Bushra; Arjuman, Albina; Chandra, Nimai Chand

    2016-08-16

    LOX-1, one of the main receptors for oxLDL, is found mainly on the surface of endothelial cells. It is a multifacet 52 kDa type II transmembrane protein that structurally belongs to the C-type lectin family. It exists with short intracellular N-terminal and long extracellular C-terminal hydrophilic domains separated by a hydrophobic domain of 26 amino acids. LOX-1 acts like a bifunctional receptor either showing pro-atherogenicity by activating the NFκB-mediated down signaling cascade for gene activation of pro-inflammatory molecules or playing an atheroprotective agent by receptor-mediated uptake of oxLDL in the presence of an anti-inflammatory molecule like IL-10. Mildly, moderately, and highly oxidized LDL show their characteristic features upon LOX-1 activation and its ligand binding indenture. The polymorphic LOX-1 genes are intensively associated with increased susceptibility to myocardial diseases. The splicing variant LOX IN dimerizes with the native form of LOX-1 and protects cells from damage by oxidized LDL. In the developing field of regenerating medicine, LOX-1 is a potential target for therapeutic intervention. PMID:27419271

  19. Influence of Estrogen Receptor α Polymorphisms on Bone Density in Response to Habitual Exercise in Japanese Postmenopausal Women

    PubMed Central

    Kondo, Hiroyo; Nagatomo, Fumiko; Ishihara, Akihiko

    2014-01-01

    Estrogen receptor α (ERα) is one of candidate genes for osteoporosis. This study examined the influence of ERα gene, PvuII, and XbaI genotypes on bone density of calcaneus in response to habitual exercise. ERα polymorphisms were detected using PvuII and XbaI restriction enzymes in 316 Japanese postmenopausal women. The bone density was significantly lower in the women carrying PP, pp, or xx genotype without habitual exercise than in the age-matched women without those genotypes. The women carrying Pp genotype without habitual exercise had normal bone density compared to those without Pp genotype. The women carrying PPxx or ppxx polymorphism without habitual exercise had low bone density compared to those with habitual exercise. Thus, the reduction of bone density was attenuated in the women carrying PPxx or ppxx with habitual exercise. In addition, habitual exercise was highly effective for the bone density in the women carrying xx homozygote. These findings indicate that analyses of XbaI and PvuII polymorphisms of ERα may be useful to predict the effect of exercise on bone density, and habitual exercise attenuates the reduction of bone density in women with some genotypes. PMID:25152917

  20. Treadmill running frequency on anxiety and hippocampal adenosine receptors density in adult and middle-aged rats.

    PubMed

    Costa, Marcelo S; Ardais, Ana Paula; Fioreze, Gabriela T; Mioranzza, Sabrina; Botton, Paulo Henrique S; Portela, Luis Valmor; Souza, Diogo O; Porciúncula, Lisiane O

    2012-01-10

    Physical exercise protocols have varied widely across studies raising the question of whether there is an optimal intensity, duration and frequency that would produce maximal benefits in attenuating symptoms related to anxiety disorders. Although physical exercise causes modifications in neurotransmission systems, the involvement of neuromodulators such as adenosine has not been investigated after chronic exercise training. Anxiety-related behavior was assessed in the elevated plus-maze in adult and middle-aged rats submitted to 8 weeks of treadmill running 1, 3 or 7 days/week. The speed of running was weekly adjusted to maintain moderate intensity. The hippocampal adenosine A1 and A2A receptors densities were also assessed. Treadmill running protocol was efficient in increasing physical exercise capacity in adult and middle-aged rats. All frequencies of treadmill running equally decreased the time spent in the open arms in adult animals. Middle-aged treadmill control rats presented lower time spent in the open arms than adult treadmill control rats. However, treadmill running one day/week reversed this age effect. Adenosine A1 receptor was not changed between groups, but treadmill running counteracted the age-related increase in adenosine A2A receptors. Although treadmill running, independent from frequency, triggered anxiety in adult rats and treadmill running one day/week reversed the age-related anxiety, no consistent relationship was found with hippocampal adenosine receptors densities. Thus, our data suggest that as a complementary therapy in the management of mental disturbances, the frequency and intensity of physical exercise should be taken into account according to age. Besides, this is the first study reporting the modulation of adenosine receptors after chronic physical exercise, which could be important to prevent neurological disorders associated to increase in adenosine A2A receptors.

  1. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    SciTech Connect

    Lee, Ha Young; Kim, Sang Doo; Baek, Suk-Hwan; Choi, Joon Hyuk; Cho, Kyung-Hyun; Zabel, Brian A.; Bae, Yoe-Sik

    2013-03-29

    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  2. A systematic investigation of the differential roles for ventral tegmentum serotonin 1- and 2-type receptors on food intake in the rat.

    PubMed

    Pratt, Wayne E; Clissold, Kara A; Lin, Peagan; Cain, Amanda E; Ciesinski, Alexa F; Hopkins, Thomas R; Ilesanmi, Adeolu O; Kelly, Erin A; Pierce-Messick, Zachary; Powell, Daniel S; Rosner, Ian A

    2016-10-01

    Central serotonin (5-HT) pathways are known to influence feeding and other ingestive behaviors. Although the ventral tegmentum is important for promoting the seeking and consumption of food and drugs of abuse, the roles of 5-HT receptor subtypes in this region on food intake have yet to be comprehensively examined. In these experiments, food restricted rats were given 2-h access to rat chow; separate groups of non-restricted animals had similar access to a sweetened fat diet. Feeding and locomotor activity were monitored following ventral tegmentum stimulation or blockade of 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2B, or 5-HT2C receptors. 5-HT1A receptor stimulation transiently inhibited rearing behavior and chow intake in food-restricted rats, and had a biphasic effect on non-restricted rats offered the palatable diet. 5-HT1B receptor agonism transiently inhibited feeding in restricted animals, but did not affect intake of non-restricted rats. In contrast, 5-HT1B receptor antagonism decreased palatable feeding. Although stimulation of ventral tegmental 5-HT2B receptors with BW723C86 did not affect hunger-driven food intake, it significantly affected palatable feeding, with a trend for an increasing intake at 2.0µg/side but not at 5.0µg/side. Antagonism of the same receptor modestly but significantly inhibited feeding of the palatable diet at 5.0µg/side ketanserin. Neither stimulation nor blockade of 5-HT2A or 5-HT2C receptors caused prolonged effects on intake or locomotion. These data suggest that serotonin's effects on feeding within the ventral tegmentum depend upon the specific receptor targeted, as well as whether intake is motivated by food restriction or the palatable nature of the offered diet. PMID:27431937

  3. A systematic investigation of the differential roles for ventral tegmentum serotonin 1- and 2-type receptors on food intake in the rat.

    PubMed

    Pratt, Wayne E; Clissold, Kara A; Lin, Peagan; Cain, Amanda E; Ciesinski, Alexa F; Hopkins, Thomas R; Ilesanmi, Adeolu O; Kelly, Erin A; Pierce-Messick, Zachary; Powell, Daniel S; Rosner, Ian A

    2016-10-01

    Central serotonin (5-HT) pathways are known to influence feeding and other ingestive behaviors. Although the ventral tegmentum is important for promoting the seeking and consumption of food and drugs of abuse, the roles of 5-HT receptor subtypes in this region on food intake have yet to be comprehensively examined. In these experiments, food restricted rats were given 2-h access to rat chow; separate groups of non-restricted animals had similar access to a sweetened fat diet. Feeding and locomotor activity were monitored following ventral tegmentum stimulation or blockade of 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2B, or 5-HT2C receptors. 5-HT1A receptor stimulation transiently inhibited rearing behavior and chow intake in food-restricted rats, and had a biphasic effect on non-restricted rats offered the palatable diet. 5-HT1B receptor agonism transiently inhibited feeding in restricted animals, but did not affect intake of non-restricted rats. In contrast, 5-HT1B receptor antagonism decreased palatable feeding. Although stimulation of ventral tegmental 5-HT2B receptors with BW723C86 did not affect hunger-driven food intake, it significantly affected palatable feeding, with a trend for an increasing intake at 2.0µg/side but not at 5.0µg/side. Antagonism of the same receptor modestly but significantly inhibited feeding of the palatable diet at 5.0µg/side ketanserin. Neither stimulation nor blockade of 5-HT2A or 5-HT2C receptors caused prolonged effects on intake or locomotion. These data suggest that serotonin's effects on feeding within the ventral tegmentum depend upon the specific receptor targeted, as well as whether intake is motivated by food restriction or the palatable nature of the offered diet.

  4. The low density lipoprotein receptor-related protein 1: Unique tissue-specific functions revealed by selective gene knockout studies

    PubMed Central

    Lillis, Anna P.; Van Duyn, Lauren B.; Murphy-Ullrich, Joanne E.; Strickland, Dudley K.

    2008-01-01

    The low-density lipoprotein (LDL) receptor-related protein (originally called LRP, but now referred to as LRP1) is a large endocytic receptor that is widely expressed in several tissues. LRP1 is a member of the LDL receptor family that plays diverse roles in various biological processes including lipoprotein metabolism, degradation of proteases, activation of lysosomal enzymes and cellular entry of bacterial toxins and viruses. Deletion of the LRP1 gene leads to lethality in mice, revealing a critical, but as of yet, undefined role in development. Tissue-specific gene deletion studies reveal an important contribution of LRP1 in the vasculature, central nervous system, in macrophages and in adipocytes. Three important properties of LRP1 dictate its diverse role in physiology: first, its ability to recognize more than thirty distinct ligands; second, its ability to bind a large number of cytoplasmic adaptor proteins via determinants located on its cytoplasmic domain in a phosphorylation-specific manner; and third, its ability to associate with and modulate the activity of other transmembrane receptors such as integrins and receptor tyrosine kinases. PMID:18626063

  5. Sustained Recreational Use of Ecstasy Is Associated with Altered Pre and Postsynaptic Markers of Serotonin Transmission in Neocortical Areas: A PET Study with [11C]DASB and [11C]MDL 100907

    PubMed Central

    Urban, Nina BL; Girgis, Ragy R; Talbot, Peter S; Kegeles, Lawrence S; Xu, X; Frankle, W Gordon; Hart, Carl L; Slifstein, Mark; Abi-Dargham, Anissa; Laruelle, Marc

    2012-01-01

    3,4-Methylenedioxymethamphetamine (MDMA), the main psychoactive component of the recreational drug ecstasy, is a potent serotonin (5-HT) releaser. In animals, MDMA induces 5-HT depletion and toxicity in 5-HT neurons. The aim of this study was to investigate both presynaptic (5-HT transporter, SERT) and postsynaptic (5-HT2A receptor) markers of 5-HT transmission in recently abstinent chronic MDMA users compared with matched healthy controls. We hypothesized that MDMA use is associated with lower SERT density and concomitant upregulation of 5-HT2A receptors. Positron emission tomography studies using the SERT ligand [11C]DASB and the 5-HT2A receptor ligand [11C]MDL 100907 were evaluated in 13 current and recently detoxified MDMA users and 13 matched healthy controls. MDMA users reported a mean duration of ecstasy use of 8 years, regular exposure, and at least 2 weeks of abstinence before the scans. SERT and 5-HT2A receptor availability (binding potential, BPND) were analyzed with a two-tissue compartment model with arterial input function. Current recreational MDMA use was significantly associated with lower SERT BPND and higher 5-HT2A receptor BPND in cortical, but not subcortical regions. Decreased SERT BPND was regionally associated with upregulated 5-HT2A receptor BPND. In light of the animal literature, the most parsimonious interpretation is that repeated exposure to MDMA in humans, even in moderate amounts, leads to damage in 5-HT neuron terminals innervating the cortex. Alterations in mood, cognition, and impulse control associated with these changes might contribute to sustain MDMA use. The reversibility of these changes upon abstinence remains to be firmly established. PMID:22353758

  6. Neurochemical correlates of accumbal dopamine D2 and amygdaloid 5-HT 1B receptor densities on observational learning of aggression.

    PubMed

    Suzuki, Hideo; Lucas, Louis R

    2015-06-01

    Social learning theory postulates that individuals learn to engage in aggressive behavior through observing an aggressive social model. Prior studies have shown that repeatedly observing aggression, also called "chronic passive exposure to aggression," changes accumbal dopamine D2 receptor (D2R) and amygdaloid 5-HT1B receptor (5-HT1BR) densities in observers. But, the association between these outcomes remains unknown. Thus, in our study, we used a rat paradigm to comprehensively examine the linkage between aggression, D2R density in the nucleus accumbens core (AcbC) and shell (AcbSh), and 5-HT1BR density in the medial (MeA), basomedial (BMA), and basolateral (BLA) amygdala following chronic passive exposure to aggression. Male Sprague-Dawley rats (N = 72) were passively exposed to either aggression or nonaggression acutely (1 day) or chronically (23 days). When observer rats were exposed to aggression chronically, they showed increased aggressive behavior and reduced D2R density in bilateral AcbSh. On the other hand, exposure to aggression, regardless of exposure length, increased the 5-HT1BR density in bilateral BLA. Finally, low D2R in the AcbSh significantly interacted with high 5-HT1BR density in the BLA to predict high levels of aggression in observer rats. Our results advance our understanding of the neurobiological mechanisms in the observational learning of aggression, highlighting that dopamine-serotonin interaction, or AcbSh-BLA interaction, may contribute to a risk factor for aggression in observers who chronically witness aggressive interactions.

  7. Neurochemical Correlates of Accumbal Dopamine D2 and Amygdaloid 5-HT1B Receptor Densities on Observational Learning of Aggression

    PubMed Central

    Suzuki, Hideo; Lucas, Louis R.

    2015-01-01

    Social learning theory postulates that individuals learn to engage in aggressive behavior through observing an aggressive social model. Prior studies have shown that repeatedly observing aggression, also called “chronic passive exposure to aggression,” changes accumbal dopamine D2 receptor (D2R) and amygdaloid 5-HT1B receptor (5-HT1BR) densities in observers. But, the association between these outcomes remains unknown. Thus, our study used a rat paradigm to comprehensively examine the linkage between aggression, D2R density in the nucleus accumbens core (AcbC) and shell (AcbSh), and 5-HT1BR density in the medial (MeA), basomedial (BMA), and basolateral (BLA) amygdala following chronic passive exposure to aggression. Male Sprague-Dawley rats (N = 72) were passively exposed to either aggression or non-aggression acutely (1 day) or chronically (23 days). When observer rats were exposed to aggression chronically, they showed increased aggressive behavior and reduced D2R density in the bilateral AcbSh. On the other hand, exposure to aggression, regardless of exposure length, increased 5-HT1BR density in the bilateral BLA. Finally, low D2R in the AcbSh significantly interacted with high 5-HT1BR density in the BLA in predicting high levels of aggression in observer rats. Our results advance our understanding of the neurobiological mechanisms for observational learning of aggression, highlighting that dopamine-serotonin interaction, or AcbSh-BLA interaction, may contribute to a risk factor for aggression in observers who chronically witness aggressive interactions. PMID:25650085

  8. PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density

    PubMed Central

    Chen, Xiaobing; Levy, Jonathan M.; Hou, Austin; Winters, Christine; Azzam, Rita; Sousa, Alioscka A.; Leapman, Richard D.; Nicoll, Roger A.; Reese, Thomas S.

    2015-01-01

    The postsynaptic density (PSD)-95 family of membrane-associated guanylate kinases (MAGUKs) are major scaffolding proteins at the PSD in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. How MAGUKs underlie synaptic strength at the molecular level is still not well understood. Here, we explore the structural and functional roles of MAGUKs at hippocampal excitatory synapses by simultaneous knocking down PSD-95, PSD-93, and synapse-associated protein (SAP)102 and combining electrophysiology and transmission electron microscopic (TEM) tomography imaging to analyze the resulting changes. Acute MAGUK knockdown greatly reduces synaptic transmission mediated by α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) and N-methyl-d-aspartate receptors (NMDARs). This knockdown leads to a significant rise in the number of silent synapses, diminishes the size of PSDs without changes in pre- or postsynaptic membrane, and depletes the number of membrane-associated PSD-95–like vertical filaments and transmembrane structures, identified as AMPARs and NMDARs by EM tomography. The differential distribution of these receptor-like structures and dependence of their abundance on PSD size matches that of AMPARs and NMDARs in the hippocampal synapses. The loss of these structures following MAGUK knockdown tracks the reduction in postsynaptic AMPAR and NMDAR transmission, confirming the structural identities of these two types of receptors. These results demonstrate that MAGUKs are required for anchoring both types of glutamate receptors at the PSD and are consistent with a structural model where MAGUKs, corresponding to membrane-associated vertical filaments, are the essential structural proteins that anchor and organize both types of glutamate receptors and govern the overall molecular organization of the PSD. PMID:26604311

  9. Changes in striatal D2-receptor density following chronic treatment with amphetamine as assessed with PET in nonhuman primates.

    PubMed

    Ginovart, N; Farde, L; Halldin, C; Swahn, C G

    1999-02-01

    Recent brain imaging studies suggest that schizophrenia may be related to abnormally high amphetamine-induced dopamine release. It is known that repeated use of amphetamine may cause paranoid psychosis and persisting stereotypies. The biochemical background for these signs and symptoms has not been clarified. In this study, positron emission tomography and [11C]raclopride were used to determine central D2-dopamine receptor density (Bmax) and apparent affinity (K(D)app) in Cynomolgus monkeys before and after 14 days of treatment with d-amphetamine sulphate (2 mg/kg/day; s.c.). One day after withdrawal from amphetamine, K(D)app was increased, suggesting [11C]raclopride competition with elevated concentration of dopamine. At 7 and 14 days after withdrawal, there was a 19-26% decrease in Bmax but no change in K(D)app as compared to baseline. Although this study was performed on two monkeys only, there was thus no support for the view that chronic intermittent hyperactivity of the dopamine system may be related to an upregulation of striatal D2-dopamine receptors. Repeated administration of amphetamine may, rather, cause a long-lasting downregulation of the D2-receptor density, which may be a neurochemical correlate to the abnormal movements, anhedonia, anxiety, and depression seen in psychostimulant abusers.

  10. Evidence for chronically altered cortical serotonin function in human female recreational ecstasy (MDMA) polydrug users

    PubMed Central

    Di Iorio, Christina R; Watkins, Tristan J; Dietrich, Mary S; Cao, Aize; Blackford, Jennifer U; Rogers, Baxter; Ansari, Mohammed S; Baldwin, Ronald M; Li, Rui; Kessler, Robert M; Salomon, Ronald M; Benningfield, Margaret; Cowan, Ronald L

    2012-01-01

    Context MDMA (ecstasy) is a popular recreational drug that produces loss of serotonin (5-HT) axons in animal models. Whether MDMA produces chronic reductions in 5-HT signaling in humans remains controversial. Objective To determine if MDMA use is associated with chronic reductions in serotonin signaling in female human cerebral cortex as reflected by increased 5-HT2A receptors. Design Cross sectional case-control study comparing 5-HT2A receptor levels in abstinent female MDMA polydrug users to MDMA-naive females; within-group design assessing the association of lifetime MDMA use and 5-HT2A receptors. Subjects had at least 90 days abstinence from MDMA use as verified by hair sampling. Cortical 5-HT2A receptor levels were assayed with the 5HT2A-specific Positron Emission Tomography (PET) radioligand [18F]setoperone. Setting Academic Medical Center Research Laboratory. Participants Volunteer female MDMA users (N=14) and MDMA-naive controls (N=10). Main exclusion criteria were non-drug-related DSM-IV axis I psychiatric disorders and general medical illness. Main Outcome Measure Cortical 5-HT2A receptor non-displaceable binding potential (5-HT2ABPND). Results MDMA users had increased 5-HT2ABPND in occipital-parietal (19.7%), temporal (20.5%), occipito-temporal-parietal (18.3%), frontal (16.6%), and fronto-parietal (18.5%) regions (p<0.05; corrected). Lifetime MDMA use associated positively with 5-HT2ABPND in fronto-parietal (β=0.665;p=0.007), occipito-temporal (β=0.798;p=0.002), fronto-limbic (β=0.634;p=0.024), and frontal (β=0.691;p=0.008) regions. In contrast, there were no regions in which MDMA use was inversely associated with receptor levels. There were no statistically significant effects of the duration of MDMA abstinence on 5-HT2ABPND. Conclusions Human recreational MDMA use is associated with long-lasting increases in 5-HT2A receptor density. 5-HT2A receptor levels correlate positively with lifetime MDMA use and do not decrease with abstinence. These

  11. Factor VIII Interacts with the Endocytic Receptor Low-density Lipoprotein Receptor-related Protein 1 via an Extended Surface Comprising "Hot-Spot" Lysine Residues.

    PubMed

    van den Biggelaar, Maartje; Madsen, Jesper J; Faber, Johan H; Zuurveld, Marleen G; van der Zwaan, Carmen; Olsen, Ole H; Stennicke, Henning R; Mertens, Koen; Meijer, Alexander B

    2015-07-01

    Lysine residues are implicated in driving the ligand binding to the LDL receptor family. However, it has remained unclear how specificity is regulated. Using coagulation factor VIII as a model ligand, we now study the contribution of individual lysine residues in the interaction with the largest member of the LDL receptor family, low-density lipoprotein receptor-related protein (LRP1). Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and SPR interaction analysis on a library of lysine replacement variants as two independent approaches, we demonstrate that the interaction between factor VIII (FVIII) and LRP1 occurs over an extended surface containing multiple lysine residues. None of the individual lysine residues account completely for LRP1 binding, suggesting an additive binding model. Together with structural docking studies, our data suggest that FVIII interacts with LRP1 via an extended surface of multiple lysine residues that starts at the bottom of the C1 domain and winds around the FVIII molecule. PMID:25903134

  12. Factor VIII Interacts with the Endocytic Receptor Low-density Lipoprotein Receptor-related Protein 1 via an Extended Surface Comprising “Hot-Spot” Lysine Residues♦

    PubMed Central

    van den Biggelaar, Maartje; Madsen, Jesper J.; Faber, Johan H.; Zuurveld, Marleen G.; van der Zwaan, Carmen; Olsen, Ole H.; Stennicke, Henning R.; Mertens, Koen; Meijer, Alexander B.

    2015-01-01

    Lysine residues are implicated in driving the ligand binding to the LDL receptor family. However, it has remained unclear how specificity is regulated. Using coagulation factor VIII as a model ligand, we now study the contribution of individual lysine residues in the interaction with the largest member of the LDL receptor family, low-density lipoprotein receptor-related protein (LRP1). Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and SPR interaction analysis on a library of lysine replacement variants as two independent approaches, we demonstrate that the interaction between factor VIII (FVIII) and LRP1 occurs over an extended surface containing multiple lysine residues. None of the individual lysine residues account completely for LRP1 binding, suggesting an additive binding model. Together with structural docking studies, our data suggest that FVIII interacts with LRP1 via an extended surface of multiple lysine residues that starts at the bottom of the C1 domain and winds around the FVIII molecule. PMID:25903134

  13. Correlation between GABA(A) receptor density and vagus nerve stimulation in individuals with drug-resistant partial epilepsy.

    PubMed

    Marrosu, Francesco; Serra, Alessandra; Maleci, Alberto; Puligheddu, Monica; Biggio, Giovanni; Piga, Mario

    2003-01-01

    Vagus nerve stimulation (VNS) is an important option for the treatment of drug-resistant epilepsy. Through delivery of a battery-supplied intermittent current, VNS protects against seizure development in a manner that correlates experimentally with electrophysiological modifications. However, the mechanism by which VNS inhibits seizures in humans remains unclear. The impairment of gamma-aminobutyric acid (GABA)-mediated neuronal inhibition associated with epilepsy has suggested that GABA(A) receptors might contribute to the therapeutic efficacy of VNS. We have now applied single photon emission computed tomography (SPECT) with the benzodiazepine receptor inverse agonist [123I]iomazenil to examine cortical GABA(A) receptor density (GRD) before and 1 year after implantation of a VNS device in 10 subjects with drug-resistant partial epilepsy. VNS therapeutic responses resulted significantly correlated with the normalization of GRD. Moreover, a comparable control group, scheduled for a possible VNS implant, failed to show significant GRD variations after 1 year of a stable anti-epileptic treatment. These results suggest that VNS may modulate the cortical excitability of brain areas associated with epileptogenesis and that GABA(A) receptor plasticity contributes to this effect.

  14. Initial hepatic removal of chylomicron remnants is unaffected but endocytosis is delayed in mice lacking the low density lipoprotein receptor.

    PubMed Central

    Herz, J; Qiu, S Q; Oesterle, A; DeSilva, H V; Shafi, S; Havel, R J

    1995-01-01

    Two endocytic receptors, the low density lipoprotein (LDL) receptor (LDLR) and the LDLR-related protein (LRP), are thought to act in concert in the hepatic uptake of partially metabolized dietary lipoproteins, the chylomicron remnants. We have evaluated the role of these two receptors in the hepatic metabolism of chylomicron remnants in normal mice and in LDLR-deficient [LDLR (-/-)] mice. The rate of chylomicron remnant removal by the liver was normal up to 30 min after intravenous injection of chylomicrons into LDLR (-/-) mice and was unaffected by receptor-associated protein (RAP), a potent inhibitor of ligand binding to LRP. In contrast, endocytosis of the remnants by the hepatocytes, measured by their accumulation in the endosomal fraction and by the rate of hydrolysis of component cholesteryl esters, was dramatically reduced in the absence of the LDLR. Coadministration of RAP prevented the continuing hepatic removal of chylomicron remnants in LDL (-/-) mice after 30 min, consistent with blockade of the slow endocytosis by a RAP-sensitive process. Taken together with previous studies, our results are consistent with a model in which the initial hepatic removal of chylomicron remnants is primarily mediated by mechanisms that do not include LDLR or LRP, possibly involving glycosaminoglycan-bound hepatic lipase and apolipoprotein E. After the remnants bind to these alternative sites on the hepatocyte surface, endocytosis is predominantly mediated by the LDLR and also by a slower and less efficient backup process that is RAP sensitive and therefore most likely involves LRP. PMID:7753850

  15. A human embryonic lung fibroblast with a high density of muscarinic acetylcholine receptors.

    PubMed

    André, C; Marullo, S; Convents, A; Lü, B Z; Guillet, J G; Hoebeke, J; Strosberg, D A

    1988-01-15

    Binding studies with the radiolabeled muscarinic antagonists dexetimide, quinuclidinyl benzilate and N-methylscopolamine showed that the human embryonic lung fibroblast CCL137 possesses approximately 2 X 10(5) muscarinic receptors/cell, i.e. 2.1 pmol/mg membrane protein. These receptors showed a marked stereoselectivity towards dexetimide and levetimide and only low affinity for another antagonist, pirenzepine. The muscarinic agonist carbamylcholine inhibited forskolin-stimulated adenylate cyclase and induced phosphatidylinositide turnover in the intact cells. Both effects were inhibited by the muscarinic antagonist atropine. Affinity labeling with tritiated propylbenzylcholine mustard revealed a protein of 72 kDa. Finally, down-regulation of the membrane receptors following prolonged treatment with the agonist carbamylcholine was assessed by means of the hydrophilic antagonist N-methylscopolamine. PMID:2828056

  16. Mitochondrial Ultrastructural Alterations and Declined M2 Receptor Density Were Involved in Cardiac Dysfunction in Rats after Long Term Treatment with Autoantibodies against M2 Muscarinic Receptor

    PubMed Central

    Wang, Jin; Wang, Li; Wu, Ye; Wang, Jie; Lv, Tingting; Liu, Huirong

    2015-01-01

    . Mitochondrial damage and the down-regulation of M2 receptor density and affinity may be involved in the process. PMID:26086781

  17. Neonatal handling reduces angiotensin II receptor density in the medial preoptic area and paraventricular nucleus but not in arcuate nucleus and locus coeruleus of female rats.

    PubMed

    Gomes, Cármen Marilei; Donadio, Márcio Vinícius Fagundes; Franskoviaki, Inélia; Anselmo-Franci, Janete A; Franci, Celso Rodrigues; Lucion, Aldo Bolten; Sanvitto, Gilberto Luiz

    2006-01-01

    Neonatal handling alters the hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic-pituitary-gonads axis (HPG) in adult animals, and angiotensin II (Ang II) modulates the functions in these axes. We tested whether neonatal handling could change the density of Ang II receptors in some central areas in female rats. Results showed decreased density of the Ang II receptors in the medial preoptic area (MPOA) and hypothalamic paraventricular nucleus (PVN) of the neonatal handled group.

  18. Oxidized low density lipoprotein receptor-1 mediates oxidized low density lipoprotein-induced apoptosis in human umbilical vein endothelial cells: role of reactive oxygen species.

    PubMed

    Chen, Xiu-ping; Xun, Ke-li; Wu, Qin; Zhang, Tian-tai; Shi, Jing-shan; Du, Guan-hua

    2007-07-01

    Studies have shown that oxidized low density lipoprotein (ox-LDL) elicits both necrotic and apoptotic cell death and several mechanisms have been proposed. Ox-LDL induces reactive oxygen species (ROS), a second messenger that might be involved in apoptosis, formation in different types of cells including endothelial cells (ECs) and smooth muscle cells (SMCs). As lectin-like ox-LDL receptor-1 (LOX-1) was the main receptor for ox-LDL, this study was designed to determine whether the apoptosis induced by ox-LDL was mediated by LOX-1 in cultured human umbilical vein endothelial cells (HUVECs) and whether there is an association between LOX-1 mediated apoptosis and the production of ROS. After exposure to ox-LDL (50,100, and 150 microg/ml for 18 h), HUVECs exhibit typical apoptotic characteristics as determined by transmission electron microscopy and flow cytometry analysis in a dose-dependent pattern. Ox-LDL increases intracellular ROS formation including superoxide anion (O2-) and hydrogen peroxide (H2O2) in a dose-dependent and time-dependent manner. Pretreatment with anti-LOX-1 mAb, Vitamin C, apocynin or catalase significantly reduced ROS production and prevented ox-LDL-induced apoptosis, while indomethacin or allopurinol had no effect. These results suggest that LOX-1 mediates ox-LDL-induced apoptosis in endothelial cells and that ROS production and NADPH oxidase might play an important role in ox-LDL-induced apoptosis.

  19. Cortical Serotonin Type-2 Receptor Density in Parents of Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Goldberg, Jeremy; Anderson, George M.; Zwaigenbaum, Lonnie; Hall, Geoffrey B. C.; Nahmias, Claude; Thompson, Ann; Szatmari, Peter

    2009-01-01

    Parents (N = 19) of children with autism spectrum disorders (ASD) and adult controls (N = 17) underwent positron emission tomography (PET) using [[superscript 18]F]setoperone to image cortical serotonin type-2 (5-HT2) receptors. The 5-HT2 binding potentials (BPs) were calculated by ratioing [[superscript 18]F]setoperone intensity in regions of…

  20. 5-Hydroxytryptamine Receptor Subtypes and their Modulators with Therapeutic Potentials

    PubMed Central

    Pithadia, Anand B.; Jain, Sunita M.

    2009-01-01

    5-hydroxytryptamine (5-HT) has become one of the most investigated and complex biogenic amines. The main receptors and their subtypes, e.g., 5-HTI (5-HT1A, 5-HT1B, 5-HTID, 5-HTIE and 5-HT1F), 5-HT2 (5-HT2A, 5-HT2B and 5-HT2C), 5-HT3, 5-HT4, 5-HT5 (5-HT5A, 5-HT5B), 5-HT6 and 5-HT7 have been identified. Specific drugs which are capable of either selectively stimulating or inhibiting these receptor subtypes are being designed. This has generated therapeutic potentials of 5-HT receptor modulators in a variety of disease conditions. Conditions where 5-HT receptor modulators have established their use with distinct efficacy and advantages include migraine, anxiety, psychosis, obesity and cancer therapy-induced vomiting by cytotoxic drugs and radiation. Discovery of 5-HT, its biosynthesis, metabolism, physiological role and the potential of 5-HT receptor modulators in various nervous, cardiovascular and gastrointestinal tract disorders, bone growth and micturition have been discussed in this article. Keywords 5-hydroxytryptamine (5-HT) receptors; Modulators; Biogenic amines PMID:22505971

  1. Regulation of the membrane estrogen receptor-α: role of cell density, serum, cell passage number, and estradiol

    PubMed Central

    CAMPBELL, CELESTE H.; BULAYEVA, NATALIYA; BROWN, DAVID B.; GAMETCHU, BAHIRU; WATSON, CHERYL S.

    2005-01-01

    We used modified immunocytochemical conditions to quantify a membrane form of estrogen receptor-α (mERα) in a rat pituitary tumor cell line, GH3/B6/F10. We studied the regulation of mERα vs. levels of intracellular ERα (iERα) using our 96-well plate immunoassay. The anti-ERα antibody C542 was used to label the ERα (via conjugated alkaline phosphatase) in fixed permeabilized (for iERα) vs. nonpermeabilized cells (for mERα). Expression of mERα was highest at low cell densities (<1000 cells/well) and decreased significantly at densities where cellular processes touched, whereas the more abundant iERα increased with increasing cell density over the same range. Serum starvation for 48 h caused increases in mERα, whereas iERα levels showed no significant changes. A large decline in mERα and iERα levels with cell passage number was observed. Minutes after nM 17β-estradiol (E2) treatment, a portion of the cells rounded up and detached from the culture plate, whereas nM cholesterol had no such effect. Although E2 treatment did not change mERα levels, the antigen was reorganized from a fine particulate to aggregation into asymmetric large granules of staining. That common culturing conditions favor down-regulation of mERα may explain the relatively few reports of this protein in other experimental systems.—Campbell, C. H., Bulayeva, N., Brown, D. B., Gametchu, B., Watson, C. S. Regulation of the membrane estrogen receptor-α: role of cell density, serum, cell passage number, and estradiol. PMID:12468456

  2. Discriminative stimulus properties of 1.25mg/kg clozapine in rats: Mediation by serotonin 5-HT2 and dopamine D4 receptors.

    PubMed

    Prus, Adam J; Wise, Laura E; Pehrson, Alan L; Philibin, Scott D; Bang-Andersen, Benny; Arnt, Jørn; Porter, Joseph H

    2016-10-01

    The atypical antipsychotic drug clozapine remains one of most effective treatments for schizophrenia, given a lack of extrapyramidal side effects, improvements in negative symptoms, cognitive impairment, and in symptoms in treatment-resistant schizophrenia. The adverse effects of clozapine, including agranulocytosis, make finding a safe clozapine-like a drug a goal for drug developers. The drug discrimination paradigm is a model of interoceptive stimulus that has been used in an effort to screen experimental drugs for clozapine-like atypical antipsychotic effects. The present study was conducted to elucidate the receptor-mediated stimulus properties that form this clozapine discriminative cue by testing selective receptor ligands in rats trained to discriminate a 1.25mg/kg dose of clozapine from vehicle in a two choice drug discrimination task. Full substitution occurred with the 5-HT2A inverse agonist M100907 and the two preferential D4/5-HT2/α1 receptor antagonists Lu 37-114 ((S)-1-(3-(2-(4-(1H-indol-5-yl)piperazin-1-yl)ethyl)indolin-1-yl)ethan-1-one) and Lu 37-254 (1-(3-(4-(1H-indol-5-yl)piperazin-1-yl)propyl)-3,4-dihydroquinolin-2(1H)-one). Partial substitution occurred with the D4 receptor antagonist Lu 38-012 and the α1 adrenoceptor antagonist prazosin. Drugs selective for 5-HT2C, 5-HT6 muscarinic, histamine H1, and benzodiazepine receptors did not substitute for clozapine. The present findings suggest that 5-HT2A inverse agonism and D4 receptor antagonism mediate the discriminative stimulus properties of 1.25mg/kg clozapine in rats, and further confirm that clozapine produces a complex compound discriminative stimulus. PMID:27502027

  3. Human Serotonin 5-HT2C G Protein-Coupled Receptor Homology Model from the β2 Adrenoceptor Structure: Ligand Docking and Mutagenesis Studies

    PubMed Central

    RDOVA-SINTJAGO, TANIA CÓ; VILLA, NANCY; CANAL, CLINTON; BOOTH, RAYMOND

    2013-01-01

    Activation of the serotonin (5-hydroxytryptamine, 5-HT) 5HT2C G protein-coupled receptor (GPCR) is proposed as novel pharmacotherapy for obesity and neuropsychiatric disorders. In contrast, activation of the 5-HT2A and 5-HT2B GPCRs is associated with untoward hallucinogenic and cardiopulmonary effects, respectively. There is no crystal structure available to guide design of 5-HT2C receptor-specific ligands. For this reason, a homology model of the 5-HT2C receptor was built based on the crystal structure of the human β2 adrenoceptor GPCR to delineate molecular determinants of ligand–receptor interactions for drug design purposes. Computational and experimental studies were carried out to validate the model. Binding of N(CH3)2-PAT [(1R, 3S)-(−)-trans-1-phenyl-3-N,N-dimethylamino-1,2,3,4-tetrahydronaphthalene], a novel 5-HT2C agonist/5-HT2A/2B inverse agonist, and its secondary [NH(CH3)-PAT] and primary (NH2-PAT) amine analogs were studied at the 5-HT2C wild type (WT) and D3.32A, S3.36A, and Y7.43A 5-HT2C point-mutated receptors. Reference ligands included the tertiary amines lisuride and mesulergine and the primary amine 5-HT. Modeling results indicated that 5-HT2C residues D3.32, S3.36, and Y7.43 play a role in ligand binding. Experimental ligand binding results with WT and point-mutated receptors confirmed the impact of D3.32, S3.36, and Y7.43 on ligand affinity. PMID:24244046

  4. Accounting for pharmacokinetic differences in dual-tracer receptor density imaging.

    PubMed

    Tichauer, K M; Diop, M; Elliott, J T; Samkoe, K S; Hasan, T; St Lawrence, K; Pogue, B W

    2014-05-21

    Dual-tracer molecular imaging is a powerful approach to quantify receptor expression in a wide range of tissues by using an untargeted tracer to account for any nonspecific uptake of a molecular-targeted tracer. This approach has previously required the pharmacokinetics of the receptor-targeted and untargeted tracers to be identical, requiring careful selection of an ideal untargeted tracer for any given targeted tracer. In this study, methodology capable of correcting for tracer differences in arterial input functions, as well as binding-independent delivery and retention, is derived and evaluated in a mouse U251 glioma xenograft model using an Affibody tracer targeted to epidermal growth factor receptor (EGFR), a cell membrane receptor overexpressed in many cancers. Simulations demonstrated that blood, and to a lesser extent vascular-permeability, pharmacokinetic differences between targeted and untargeted tracers could be quantified by deconvolving the uptakes of the two tracers in a region of interest devoid of targeted tracer binding, and therefore corrected for, by convolving the uptake of the untargeted tracer in all regions of interest by the product of the deconvolution. Using fluorescently labeled, EGFR-targeted and untargeted Affibodies (known to have different blood clearance rates), the average tumor concentration of EGFR in four mice was estimated using dual-tracer kinetic modeling to be 3.9 ± 2.4 nM compared to an expected concentration of 2.0 ± 0.4 nM. However, with deconvolution correction a more equivalent EGFR concentration of 2.0 ± 0.4 nM was measured. PMID:24743262

  5. Accounting for pharmacokinetic differences in dual-tracer receptor density imaging

    NASA Astrophysics Data System (ADS)

    Tichauer, K. M.; Diop, M.; Elliott, J. T.; Samkoe, K. S.; Hasan, T.; St. Lawrence, K.; Pogue, B. W.

    2014-05-01

    Dual-tracer molecular imaging is a powerful approach to quantify receptor expression in a wide range of tissues by using an untargeted tracer to account for any nonspecific uptake of a molecular-targeted tracer. This approach has previously required the pharmacokinetics of the receptor-targeted and untargeted tracers to be identical, requiring careful selection of an ideal untargeted tracer for any given targeted tracer. In this study, methodology capable of correcting for tracer differences in arterial input functions, as well as binding-independent delivery and retention, is derived and evaluated in a mouse U251 glioma xenograft model using an Affibody tracer targeted to epidermal growth factor receptor (EGFR), a cell membrane receptor overexpressed in many cancers. Simulations demonstrated that blood, and to a lesser extent vascular-permeability, pharmacokinetic differences between targeted and untargeted tracers could be quantified by deconvolving the uptakes of the two tracers in a region of interest devoid of targeted tracer binding, and therefore corrected for, by convolving the uptake of the untargeted tracer in all regions of interest by the product of the deconvolution. Using fluorescently labeled, EGFR-targeted and untargeted Affibodies (known to have different blood clearance rates), the average tumor concentration of EGFR in four mice was estimated using dual-tracer kinetic modeling to be 3.9 ± 2.4 nM compared to an expected concentration of 2.0 ± 0.4 nM. However, with deconvolution correction a more equivalent EGFR concentration of 2.0 ± 0.4 nM was measured.

  6. Culture density regulates both the cholinergic phenotype and the expression of the CNTF receptor in P19 neurons.

    PubMed

    Parnas, D; Linial, M

    1997-04-01

    The P19 embryonal carcinoma cells differentiate into neurons, astrocytes, and fibroblast-like cells following induction with retinoic acid. The cells mature into functional neurons, as determined by their ability to release neurotransmitters in a Ca(2+)- and depolarization-dependent manner. P19 neurons in culture represent a mixed population in terms of their neurotransmitter phenotype. The cholinergic phenotype of these neurons is modulated by culture density. Cholinergic markers, such as the vesicular acetylcholine transporter, acetyl cholinesterase, and choline acetyltransferase, are expressed in about 85% of the cells in sparse cultures and are largely suppressed at high cell densities. In contrast, glutamate release is enhanced in dense P19 neuronal cultures. The factor mediating the density effect is concentrated exclusively on the cell membrane of P19 neurons and not on the nonneuronal cells, which also differentiate from P19 embryonal carcinoma cells. This membrane-associated component retains its functionality, even after membrane fixation. The downregulation of the cholinergic properties in dense cultures is paralleled by a downregulation of the alpha subunit of the ciliary neurotrophic factor (CNTF) receptor. Thus, it is suggested that the membrane-associated factor, which mediates the density effect, downregulates the cholinergic phenotype by inhibiting the responsiveness of these neurons to CNTF. We further suggest that the P19 cell line can serve as a model system for the study of neurotransmitter phenotype acquisition and plasticity throughout neuronal differentiation. PMID:9188041

  7. Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis

    SciTech Connect

    Williams, K.J.; Vallabhajosula, S.; Rahman, I.U.; Donnelly, T.M.; Parker, T.S.; Weinrauch, M.; Goldsmith, S.J.

    1988-01-01

    The metabolism of infused /sup 111/In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t/sub 1/2/) for clearance of /sup 111/In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits. By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue sores. Disappearance of excess plasma cholesterol was > 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative ..gamma.. camera imaging, hepatic trapping of /sup 111/In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance. Aortic uptake of /sup 111/In was < 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, the results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.

  8. Effects of High Fat Feeding and Diabetes on Regression of Atherosclerosis Induced by Low-Density Lipoprotein Receptor Gene Therapy in LDL Receptor-Deficient Mice

    PubMed Central

    Willecke, Florian; Yuan, Chujun; Oka, Kazuhiro; Chan, Lawrence; Hu, Yunying; Barnhart, Shelley; Bornfeldt, Karin E.; Goldberg, Ira J.; Fisher, Edward A.

    2015-01-01

    We tested whether a high fat diet (HFD) containing the inflammatory dietary fatty acid palmitate or insulin deficient diabetes altered the remodeling of atherosclerotic plaques in LDL receptor knockout (Ldlr-/-) mice. Cholesterol reduction was achieved by using a helper-dependent adenovirus (HDAd) carrying the gene for the low-density lipoprotein receptor (Ldlr; HDAd-LDLR). After injection of the HDAd-LDLR, mice consuming either HFD, which led to insulin resistance but not hyperglycemia, or low fat diet (LFD), showed regression compared to baseline. However there was no difference between the two groups in terms of atherosclerotic lesion size, or CD68+ cell and lipid content. Because of the lack of effects of these two diets, we then tested whether viral-mediated cholesterol reduction would lead to defective regression in mice with greater hyperglycemia. In both normoglycemic and streptozotocin (STZ)-treated hyperglycemic mice, HDAd-LDLR significantly reduced plasma cholesterol levels, decreased atherosclerotic lesion size, reduced macrophage area and lipid content, and increased collagen content of plaque in the aortic sinus. However, reductions in anti-inflammatory and ER stress-related genes were less pronounced in STZ-diabetic mice compared to non-diabetic mice. In conclusion, HDAd-mediated Ldlr gene therapy is an effective and simple method to induce atherosclerosis regression in Ldlr-/- mice in different metabolic states. PMID:26046657

  9. Low-density Lipoprotein Receptor-related Proteins in a Novel Mechanism of Axon Guidance and Peripheral Nerve Regeneration.

    PubMed

    Landowski, Lila M; Pavez, Macarena; Brown, Lachlan S; Gasperini, Robert; Taylor, Bruce V; West, Adrian K; Foa, Lisa

    2016-01-15

    The low-density lipoprotein receptor-related protein receptors 1 and 2 (LRP1 and LRP2) are emerging as important cell signaling mediators in modulating neuronal growth and repair. We examined whether LRP1 and LRP2 are able to mediate a specific aspect of neuronal growth: axon guidance. We sought to identify LRP1 and LRP2 ligands that could induce axonal chemoattraction, which might have therapeutic potential. Using embryonic sensory neurons (rat dorsal root ganglia) in a growth cone turning assay, we tested a range of LRP1 and LRP2 ligands for the ability to guide growth cone navigation. Three ligands were chemorepulsive: α-2-macroglobulin, tissue plasminogen activator, and metallothionein III. Conversely, only one LRP ligand, metallothionein II, was found to be chemoattractive. Chemoattraction toward a gradient of metallothionein II was calcium-dependent, required the expression of both LRP1 and LRP2, and likely involves further co-receptors such as the tropomyosin-related kinase A (TrkA) receptor. The potential for LRP-mediated chemoattraction to mediate axonal regeneration was examined in vivo in a model of chemical denervation in adult rats. In these in vivo studies, metallothionein II was shown to enhance epidermal nerve fiber regeneration so that it was complete within 7 days compared with 14 days in saline-treated animals. Our data demonstrate that both LRP1 and LRP2 are necessary for metallothionein II-mediated chemotactic signal transduction and that they may form part of a signaling complex. Furthermore, the data suggest that LRP-mediated chemoattraction represents a novel, non-classical signaling system that has therapeutic potential as a disease-modifying agent for the injured peripheral nervous system.

  10. Low-density Lipoprotein Receptor-related Proteins in a Novel Mechanism of Axon Guidance and Peripheral Nerve Regeneration*

    PubMed Central

    Landowski, Lila M.; Pavez, Macarena; Brown, Lachlan S.; Gasperini, Robert; Taylor, Bruce V.; West, Adrian K.; Foa, Lisa

    2016-01-01

    The low-density lipoprotein receptor-related protein receptors 1 and 2 (LRP1 and LRP2) are emerging as important cell signaling mediators in modulating neuronal growth and repair. We examined whether LRP1 and LRP2 are able to mediate a specific aspect of neuronal growth: axon guidance. We sought to identify LRP1 and LRP2 ligands that could induce axonal chemoattraction, which might have therapeutic potential. Using embryonic sensory neurons (rat dorsal root ganglia) in a growth cone turning assay, we tested a range of LRP1 and LRP2 ligands for the ability to guide growth cone navigation. Three ligands were chemorepulsive: α-2-macroglobulin, tissue plasminogen activator, and metallothionein III. Conversely, only one LRP ligand, metallothionein II, was found to be chemoattractive. Chemoattraction toward a gradient of metallothionein II was calcium-dependent, required the expression of both LRP1 and LRP2, and likely involves further co-receptors such as the tropomyosin-related kinase A (TrkA) receptor. The potential for LRP-mediated chemoattraction to mediate axonal regeneration was examined in vivo in a model of chemical denervation in adult rats. In these in vivo studies, metallothionein II was shown to enhance epidermal nerve fiber regeneration so that it was complete within 7 days compared with 14 days in saline-treated animals. Our data demonstrate that both LRP1 and LRP2 are necessary for metallothionein II-mediated chemotactic signal transduction and that they may form part of a signaling complex. Furthermore, the data suggest that LRP-mediated chemoattraction represents a novel, non-classical signaling system that has therapeutic potential as a disease-modifying agent for the injured peripheral nervous system. PMID:26598525

  11. Acute physical stress induces the alteration of the serotonin 1A receptor density in the hippocampus.

    PubMed

    Choi, Jae Yong; Shin, Sora; Lee, Minkyung; Jeon, Tae Joo; Seo, Youngbeom; Kim, Chul Hoon; Kim, Dong Goo; Yi, Chi Hoon; Lee, Kyochul; Choi, Tae Hyun; Kang, Jee Hae; Ryu, Young Hoon

    2014-08-01

    Stress affects the serotonergic system, which is associated with depression. Previous research has showed that chronic stress causes the deactivation of the limbic system. However, the influence of the acute physical stress on the serotonergic system in vivo was primarily unclear. The purpose of this research is to elucidate the effects of the acute physical stress in vivo using PET. For quantification of the 5-HT1A receptors in the brain, we measured [(18)F]Mefway uptake in the two experiment groups (control and despair rats). The despair group was subjected to the external stressful situation (i.e., forced swimming) and total duration time of immobility, refers to the despair severity, and was analyzed. In the intercomparison experiment, the resulting PET images of [(18)F]Mefway in the despair rat displayed a significant reduction of radioactivity in the hippocampus (HP) compared with the control. The nondisplaceable binding potential (BPND ) refers to the ratio of the concentration of radioligand in the receptor-rich region (i.e., HP) to the concentration of that in the receptor-free region (i.e., cerebellum). The hippocampal uptake and the BPND in the despair group were respectively about 25 and 18% lower than those of the control group. The ratio of specific binding to nonspecific binding in the despair group was 18% lower than that of the control. In the intracomparison experiments, the BPND and immobility in the despair group showed a strong negative correlation. Taken together, the data illustrates that an acute physical stress induces the change in the serotonergic system that correlates with the behavioral despair.

  12. Serotonin aggravates exercise-induced cardiac ischemia in the dog: effect of serotonin receptor antagonists.

    PubMed

    Guilbert, Frédérique; Lainée, Pierre; Dubreuil, Brigitte; McCort, Gary; O'Connor, Stephen E; Janiak, Philip; Herbert, Jean-Marc

    2004-08-16

    We investigated the effects of serotonin (5-HT), SL65.0472 (7-fluoro-2-oxo-4-[2-[4-thieno[3,2-c]pyridine-4-yl)piperazin-1-yl]ethyl]-1,2-dihydroquinoline-1-acetamide, a 5-HT(1B)/5-HT(2A) receptor antagonist) and ketanserin (a 5-HT(2A) receptor antagonist) during exercise-induced cardiac ischemia in conscious dogs. Dogs were administered a hypercholesterolemic diet and an inhibitor of nitric oxide synthetase to produce chronic endothelial dysfunction. Myocardial ischemia was induced by a treadmill exercise test associated with limitation of left anterior descending coronary blood flow. Infusion of serotonin during exercise produced dose-related cardiovascular changes (after 10 microg/kg/min; heart rate +27+/-6 bpm, systolic blood pressure +18+/-3 mm Hg, left circumflex coronary blood flow +64+/-8 ml/min, myocardial segment length shortening in the ischemic zone -5.9+/-1.9%, P<0.05). SL65.0472 blocked serotonin-induced increases in blood pressure, rate pressure product and circumflex coronary artery flow (100 microg/kg i.v., P<0.05) and reduced serotonin-induced ischemic myocardial segment length shortening (300 microg/kg i.v., P<0.05). Ketanserin (30-300 microg/kg i.v.) had no significant effect on any serotonin-induced changes during exercise. Thus, SL65.0472 opposes serotonin-induced myocardial dysfunction in a dog model of exercise-induced ischemia.

  13. Low-density lipoprotein receptor genetic polymorphism in chronic hepatitis C virus Egyptian patients affects treatment response

    PubMed Central

    Naga, Mazen; Amin, Mona; Algendy, Dina; Elbadry, Ahmed; Fawzi, May; Foda, Ayman; Esmat, Serag; Sabry, Dina; Rashed, Laila; Gabal, Samia; Kamal, Manal

    2015-01-01

    AIM: To correlate a genetic polymorphism of the low-density lipoprotein (LDL) receptor with antiviral responses in Egyptian chronic hepatitis C virus (HCV) patients. METHODS: Our study included 657 HCV-infected patients with genotype 4 who received interferon-based combination therapy. Patients were divided into two groups based on their response to therapy: 356 were responders, and 301 were non-responders. Patients were compared to 160 healthy controls. All patients and controls underwent a thorough physical examination, measurement of body mass index (BMI) and the following laboratory tests: serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, albumin, total bilirubin, direct bilirubin, prothrombin time, prothrombin concentration, INR, complete blood count, serum creatinine, fasting blood sugar, HCV antibody, and hepatitis B surface antigen. All HCV patients were further subjected to the following laboratory tests: HCV-RNA using quantitative polymerase chain reaction (PCR), antinuclear antibodies, thyroid-stimulating hormone, an LDL receptor (LDLR) genotype study of LDLR exon8c.1171G>A and exon10c.1413G>A using real-time PCR-based assays, abdominal ultrasonography, ultrasonographic-guided liver biopsy, and histopathological examination of liver biopsies. Correlations of LDL receptor polymorphisms with HAI, METAVIR score, presence of steatosis, and BMI were performed in all cases. RESULTS: There were no statistically significant differences in response rates between the different types of interferon used or LDLR exon10c.1413G>A. However, there was a significant difference in the frequency of the LDL receptor exon8c.1171G>A genotype between cases (AA: 25.9%, GA: 22.2%, GG: 51.9%) and controls (AA: 3.8%, GA: 53.1% and GG: 43.1%) (P < 0.001). There was a statistically significant difference in the frequency of the LDLR exon 8C:1171 G>A polymorphism between responders (AA: 3.6%, GA: 15.2%, GG: 81.2%) and non-responders (AA: 52.2%, GA: 30

  14. Antagonism of lateral saphenous vein serotonin receptors from steers grazing endophyte-free, wild-type, or novel endophyte-infected tall fescue.

    PubMed

    Klotz, J L; Aiken, G E; Johnson, J M; Brown, K R; Bush, L P; Strickland, J R

    2013-09-01

    Pharmacologic profiling of serotonin (5HT) receptors of bovine lateral saphenous vein has shown that cattle grazing endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum) have altered responses to ergovaline, 5HT, 5HT2A, and 5HT7 agonists. To determine if 5HT receptor activity of tall fescue alkaloids is affected by grazing endophyte-free (EF), wild-type [Kentucky-31 (KY31)], novel endophyte AR542-infected (MAXQ), or novel endophyte AR584-infected (AR584) tall fescue, contractile responses of lateral saphenous veins biopsied from cattle grazing these different fescue-endophyte combinations were evaluated in presence or absence of antagonists for 5HT2A (ketanserin) or 5HT7 (SB-269970) receptors. Biopsies were conducted over 2 yr on 35 mixed-breed steers (361.5 ± 6.3 kg) grazing EF (n = 12), KY31 (n = 12), MAXQ (n = 6), or AR584 (n = 5) pasture treatments (3 ha) between 84 and 98 d (Yr 1) or 108 to 124 d (Yr 2). Segments (2 to 3 cm) of vein were surgically biopsied, sliced into 2- to 3-mm cross-sections, and suspended in a myograph chamber containing 5 mL of oxygenated Krebs-Henseleit buffer (95% O2/5% CO2; pH = 7.4; 37°C). Veins were exposed to increasing concentrations of 5HT, ergovaline, and ergovaline + 1 × 10(-5) M ketanserin or + 1 × 10(-6) M SB-269970 in Yr 1. In Yr 2, ergotamine and ergocornine were evaluated in presence or absence of 1 × 10(-5) M ketanserin. Contractile response data were normalized to a reference addition of 1 × 10(-4) M norepinephrine. In Yr 1, contractile response to 5HT and ergovaline were least (P < 0.05) in KY31 pastures and the presence of ketanserin greatly reduced (P < 0.05) the response to ergovaline in all pastures. However, presence of SB-269970 did not (P = 0.91) alter contractile response to ergovaline. In Yr 2, there was no difference in contractile response to ergotamine (P = 0.13) or ergocornine (P = 0.99) across pasture treatments, but ketanserin reduced (P < 0.05) the contractile response to

  15. Translational neurophysiological markers for activity of the metabotropic glutamate receptor (mGluR2) modulator JNJ-40411813: Sleep EEG correlates in rodents and healthy men.

    PubMed

    Ahnaou, A; de Boer, P; Lavreysen, H; Huysmans, H; Sinha, V; Raeymaekers, L; Van De Casteele, T; Cid, J M; Van Nueten, L; Macdonald, G J; Kemp, J A; Drinkenburg, W H I M

    2016-04-01

    Alterations in rapid eye movement sleep (REM) have been suggested as valid translational efficacy markers: activation of the metabotropic glutamate receptor 2 (mGluR2) was shown to increase REM latency and to decrease REM duration. The present paper addresses the effects on vigilance states of the mGluR2 positive allosteric modulator (PAM) JNJ-40411813 at different circadian times in rats and after afternoon dosing in humans. Due to its dual mGluR2 PAM/serotonin 2A (5-HT2A) receptor antagonism in rodents, mGlu2R specificity of effects was studied in wild-type (WT) and mGluR2 (-/-) mice. 5-HT2A receptor occupancy was determined in humans using positron emission tomography (PET). Tolerance development was examined in rats after chronic dosing. EEG oscillations and network connectivity were assessed using multi-channel EEG. In rats, JNJ-40411813 increased deep sleep time and latency of REM onset but reduced REM time when administered 2 h after 'lights on' (CT2): this was sustained after chronic dosing. At CT5 similar effects were elicited, at CT10 only deep sleep was enhanced. Withdrawal resulted in baseline values, while re-administration reinstated drug effects. Parieto-occipital cortical slow theta and gamma oscillations were correlated with low locomotion. The specificity of functional response was confirmed in WT but not mGluR2 (-/-) mice. A double-blind, placebo-controlled polysomnographic study in healthy, elderly subjects showed that 500 mg of JNJ-40411813 consistently increased deep sleep time, but had no effect on REM parameters. This deep sleep effect was not explained by 5-HT2A receptor binding, as in the PET study even 700 mg only marginally displaced the tracer. JNJ-40411813 elicited comparable functional responses in rodents and men if circadian time of dosing was taken into account. These findings underscore the translational potential of sleep mechanisms in evaluating mGluR2 therapeutics when administered at the appropriate circadian time.

  16. Combined unilateral blockade of cholinergic, peptidergic, and serotonergic receptors in the ventral respiratory column does not affect breathing in awake or sleeping goats

    PubMed Central

    Muere, Clarissa; Neumueller, Suzanne; Olesiak, Samantha; Miller, Justin; Langer, Thomas; Hodges, Matthew R.; Pan, Lawrence

    2015-01-01

    Previous work in intact awake and sleeping goats has found that unilateral blockade of excitatory inputs in the ventral respiratory column (VRC) elicits changes in the concentrations of multiple neurochemicals, including serotonin (5-HT), substance P, glycine, and GABA, while increasing or having no effect on breathing. These findings are consistent with the concept of interdependence between neuromodulators, whereby attenuation of one modulator elicits compensatory changes in other modulators to maintain breathing. Because there is a large degree of redundancy and multiplicity of excitatory inputs to the VRC, we herein tested the hypothesis that combined unilateral blockade of muscarinic acetylcholine (mACh), neurokinin-1 (NK1, the receptor for substance P), and 5-HT2A receptors would elicit changes in multiple neurochemicals, but would not change breathing. We unilaterally reverse-dialyzed a cocktail of antagonists targeting these receptors into the VRC of intact adult goats. Breathing was continuously monitored while effluent fluid from dialysis was collected for quantification of neurochemicals. We found that neither double blockade of mACh and NK1 receptors, nor triple blockade of mACh, NK1, and 5-HT2A receptors significantly affected breathing (P ≥ 0.05) in goats that were awake or in non-rapid eye movement (NREM) sleep. However, both double and triple blockade increased the effluent concentration of substance P (P < 0.001) and decreased GABA concentrations. These findings support our hypothesis and, together with past data, suggest that both in wakefulness and NREM sleep, multiple neuromodulator systems collaborate to stabilize breathing when a deficit in one or multiple excitatory neuromodulators exists. PMID:26023224

  17. Electric field-induced redistribution and postfield relaxation of low density lipoprotein receptors on cultured human fibroblasts

    PubMed Central

    1985-01-01

    The lateral mobility of unliganded low density lipoprotein-receptor (LDL-R) on the surface of human fibroblasts has been investigated by studying the generation and relaxation of concentration differences induced by exposure of the cultured cells to steady electric fields. The topographic distribution of receptors was determined by fluorescence microscopy of cells labeled with the intensely fluorescent, biologically active LDL derivative dioctadecylindolcarbocyanine LDL (dil(3)-LDL), or with native LDL and anti-LDL indirect immunofluorescence. Exposure of the LDL-receptor- internalization defective J. D. cells (GM2408A) to an electric field of 10 V/cm for 1 h at 22 degrees C causes greater than 80% of the cells to have an asymmetric distribution of LDL-R; receptors accumulate at the more negative pole of the cell. In contrast, only 20% of LDL- internalization normal GM3348 cells exposed to identical conditions have asymmetrical distributions. Phase micrographs taken during electric-field exposure rule out cell movement as the responsible mechanism for the effect. In both cell types, postfield labeling with the F-actin-specific fluorescent probe nitrobenzoxadiazole-phallacidin shows that no topographic alteration of the actin cytoskeleton accompanies the redistribution of cell surface LDL-Rs, and indirect immunofluorescence labeling of the coat protein clathrin shows that coated pits do not redistribute asymmetrically. Measurements of the postfield relaxation in the percentage of GM2408A cells showing an asymmetric distribution allow an estimate of the effective postfield diffusion coefficient of the unliganded LDL-R. At 37 degrees C, D = 2.0 X 10(-9) cm2/s, decreasing to 1.1 X 10(-9) cm2/s at 22 degrees C, and D = 3.5 X 10(-10) cm2/s at 10 degrees C. These values are substantially larger than those measured by photobleaching methods for the LDL-R complexed with dil(3)-LDL on intact cells, but are comparable to those measured on membrane blebs, and are consistent

  18. Comparative analysis of oxytocin receptor density in the nucleus accumbens: an adaptation for female and male alloparental care?

    PubMed

    Olazábal, Daniel E

    2014-01-01

    Parental behavior is commonly displayed by progenitors. However, other individuals, genetically related (e.g. siblings, aunts, uncles) or not with the newborns, also display parental behavior (commonly called alloparental, or adoptive behavior). I hypothesize that species that live in family or social groups where other non-reproductive members (males and females) take care of infants, have brain adaptations to promote or facilitate that behavioral response. The present work revises the evidence supporting the hypothesis that high density of oxytocin receptors (OXTR) in the nucleus accumbens (NA) is one of those adaptations. All species known to have high NA OXTR show not only female, but also male alloparental care. Therefore, I predict that high NA OXTR could be present in all species in which juvenile and adult male alloparental behavior have been observed. Strategies to test this and other alternative working hypothesis and its predictions are presented. PMID:25446893

  19. Expression of low density lipoprotein receptor-related protein 4 (Lrp4) gene in the mouse germ cells.

    PubMed

    Yamaguchi, Yasuka L; Tanaka, Satomi S; Kasa, Miyuki; Yasuda, Kunio; Tam, Patrick P L; Matsui, Yasuhisa

    2006-08-01

    The low density lipoprotein receptor-related protein 4 gene (Lrp4) was identified by subtractive screening of cDNAs of the migratory primordial germ cells (PGCs) of E8.5-9.5 embryo and E3.5 blastocysts. Lrp4 is expressed in PGCs in the hindgut and the dorsal mesentery of E9.5 embryos, and in germ cells in the genital ridges of male and female E10.5-13.5 embryos. Lrp4 is also expressed in spermatogonia of the neonatal and adult testes and in the immature oocytes and follicular cells of the adult ovary. The absence of Lrp4 expression in the blastocyst, embryonic stem cells and embryonic germ cells suggests the Lrp4 is a molecular marker that distinguishes the germ cells from embryo-derived pluripotent stem cells. PMID:16434236

  20. Association of mammographic density with hormone receptors in invasive breast cancers: results from a case-only study.

    PubMed

    Heusinger, Katharina; Jud, Sebastian M; Häberle, Lothar; Hack, Carolin C; Adamietz, Boris R; Meier-Meitinger, Martina; Lux, Michael P; Wittenberg, Thomas; Wagner, Florian; Loehberg, Christian R; Uder, Michael; Hartmann, Arndt; Schulz-Wendtland, Rüdiger; Beckmann, Matthias W; Fasching, Peter A

    2012-12-01

    For many breast cancer (BC) risk factors, there is growing evidence concerning molecular subtypes for which the risk factor is specific. With regard to mammographic density (MD), there are inconsistent data concerning its association with estrogen receptor (ER) and progesterone receptor (PR) expression. The aim of our study was to analyze the association between ER and PR expression and MD. In our case-only study, data on BC risk factors, hormone receptor expression and MD were available for 2,410 patients with incident BC. MD was assessed as percent MD (PMD) using a semiautomated method by two readers for every patient. The association of ER/PR and PMD was studied with multifactorial analyses of covariance with PMD as the target variable and including well-known factors that are also associated with MD, such as age, parity, use of hormone replacement therapy, and body mass index (BMI). In addition to the commonly known associations between PMD and age, parity, BMI and hormone replacement therapy, a significant inverse association was found between PMD and ER expression levels. Patients with ER-negative tumors had an average PMD of 38%, whereas patients with high ER expression had a PMD of 35%. A statistical trend toward a positive association between PMD and PR expression was also seen. PMD appears to be inversely associated with ER expression and may correlate positively with PR expression. These effects were independent of other risk factors such as age, BMI, parity, and hormone replacement therapy, possibly suggesting other pathways that mediate this effect.

  1. Chronic Aerobic Exercise Decreases Lectin-Like Low Density Lipoprotein (LOX-1) Receptor Expression in Heart of Diabetic Rat

    PubMed Central

    Riahi, Simin; Mohammadi, Mohammad Taghi; Sobhani, Vahid; Ababzadeh, Shima

    2016-01-01

    Background: Overexpression of lectin-like low density lipoprotein (LOX-1) receptor plays an important role in hyperglycemia-induced vascular complications such as atherosclerosis. Based on the beneficial effects of exercise on preventing cardiovascular complications of diabetes, we aimed to examine the protective effects of aerobic exercise on expression of LOX-1 receptor and production of free radicals in the heart of diabetic rats. Methods: Four groups of rats were used: (n = 5 per group): sedentary normal, trained normal, sedentary diabetes and trained diabetes. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg/kg). The exercise protocol was consisted of swimming 30 min/day, 5 days/week for eight weeks. Plasma glucose was evaluated at initiation, weeks 4 and 8 of experiment. At the end of experiment, rats were sacrificed and the heart was removed for determination of nitrate, malondialdehyde, and LOX-1 gene expression. Results: In normal non-diabetic rats, the blood glucose level was <150 mg/dl; however, the induction of diabetes resulted in levels more than >400 mg/dl. Gene expression of LOX-1 was increased in the heart of diabetic rats. Exercise reduced the gene expression of this protein in diabetic states without reducing the blood glucose. Finally, swimming exercise decreased the malondialdehyde and nitrate levels in heart tissue both in control and diabetic rats. Conclusion: Swimming exercise reduces heart expression of the LOX-1 receptor in accompany with reduction of free radicals production. Since these parameters are important in generation of diabetic complications, swimming exercise is a good candidate for reducing these complications. PMID:26432573

  2. Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis.

    PubMed Central

    Williams, K J; Vallabhajosula, S; Rahman, I U; Donnelly, T M; Parker, T S; Weinrauch, M; Goldsmith, S J

    1988-01-01

    The metabolism of infused 111In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t1/2) for clearance of 111In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits (means +/- SEM; n = 4). By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue stores. Disappearance of excess plasma cholesterol was greater than 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative gamma camera imaging, hepatic trapping of 111In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance, acquiring 22.0% +/- 1.7% (WHHL) and 16.8% +/- 1.0% (normal of total 111In. Aortic uptake of 111In was less than 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, our results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia. PMID:3422421

  3. Functional Selectivity and Antidepressant Activity of Serotonin 1A Receptor Ligands

    PubMed Central

    Chilmonczyk, Zdzisław; Bojarski, Andrzej Jacek; Pilc, Andrzej; Sylte, Ingebrigt

    2015-01-01

    Serotonin (5-HT) is a monoamine neurotransmitter that plays an important role in physiological functions. 5-HT has been implicated in sleep, feeding, sexual behavior, temperature regulation, pain, and cognition as well as in pathological states including disorders connected to mood, anxiety, psychosis and pain. 5-HT1A receptors have for a long time been considered as an interesting target for the action of antidepressant drugs. It was postulated that postsynaptic 5-HT1A agonists could form a new class of antidepressant drugs, and mixed 5-HT1A receptor ligands/serotonin transporter (SERT) inhibitors seem to possess an interesting pharmacological profile. It should, however, be noted that 5-HT1A receptors can activate several different biochemical pathways and signal through both G protein-dependent and G protein-independent pathways. The variables that affect the multiplicity of 5-HT1A receptor signaling pathways would thus result from the summation of effects specific to the host cell milieu. Moreover, receptor trafficking appears different at pre- and postsynaptic sites. It should also be noted that the 5-HT1A receptor cooperates with other signal transduction systems (like the 5-HT1B or 5-HT2A/2B/2C receptors, the GABAergic and the glutaminergic systems), which also contribute to its antidepressant and/or anxiolytic activity. Thus identifying brain specific molecular targets for 5-HT1A receptor ligands may result in a better targeting, raising a hope for more effective medicines for various pathologies. PMID:26262615

  4. Functional Selectivity and Antidepressant Activity of Serotonin 1A Receptor Ligands.

    PubMed

    Chilmonczyk, Zdzisław; Bojarski, Andrzej Jacek; Pilc, Andrzej; Sylte, Ingebrigt

    2015-01-01

    Serotonin (5-HT) is a monoamine neurotransmitter that plays an important role in physiological functions. 5-HT has been implicated in sleep, feeding, sexual behavior, temperature regulation, pain, and cognition as well as in pathological states including disorders connected to mood, anxiety, psychosis and pain. 5-HT1A receptors have for a long time been considered as an interesting target for the action of antidepressant drugs. It was postulated that postsynaptic 5-HT1A agonists could form a new class of antidepressant drugs, and mixed 5-HT1A receptor ligands/serotonin transporter (SERT) inhibitors seem to possess an interesting pharmacological profile. It should, however, be noted that 5-HT1A receptors can activate several different biochemical pathways and signal through both G protein-dependent and G protein-independent pathways. The variables that affect the multiplicity of 5-HT1A receptor signaling pathways would thus result from the summation of effects specific to the host cell milieu. Moreover, receptor trafficking appears different at pre- and postsynaptic sites. It should also be noted that the 5-HT1A receptor cooperates with other signal transduction systems (like the 5-HT1B or 5-HT2A/2B/2C receptors, the GABAergic and the glutaminergic systems), which also contribute to its antidepressant and/or anxiolytic activity. Thus identifying brain specific molecular targets for 5-HT1A receptor ligands may result in a better targeting, raising a hope for more effective medicines for various pathologies. PMID:26262615

  5. Low-density lipoprotein receptor-related protein 1: a physiological Aβ homeostatic mechanism with multiple therapeutic opportunities

    PubMed Central

    Sagare, Abhay P.; Deane, Rashid; Zlokovic, Berislav V.

    2012-01-01

    Low-density lipoprotein receptor-related protein-1 (LRP1) is the main cell surface receptor involved in brain and systemic clearance of the Alzheimer's disease (AD) toxin amyloid-beta (Aβ). In plasma, a soluble form of LRP1 (sLRP1) is the major transport protein for peripheral Aβ. LRP1 in brain endothelium and mural cells mediates Aβ efflux from brain by providing a transport mechanism for A across the blood-brain barrier (BBB). sLRP1 maintains a plasma ‘sink’ activity for Aβ through binding of peripheral Aβ which in turn inhibits re-entry of free plasma Aβ into the brain. LRP1 in the liver mediates systemic clearance of Aβ. In AD, LRP1 expression at the BBB is reduced and Aβ binding to circulating sLRP1 is compromised by oxidation. Cell surface LRP1 and circulating sLRP1 represent druggable targets which can be therapeutically modified to restore the physiological mechanisms of brain Aβ homeostasis. In this review, we discuss how increasing LRP1 expression at the BBB and liver with lifestyle changes, statins, plant-based active principles and/or gene therapy on one hand, and how replacing dysfunctional plasma sLRP1 on the other regulate Aβ clearance from brain ultimately controlling the onset and/or progression of AD. PMID:22820095

  6. Sympathetic denervation does not alter the density or properties of alpha-1 adrenergic receptors in rat vas deferens

    SciTech Connect

    Abel, P.W.; Johnson, R.D.; Martin, T.J.; Minneman, K.P.

    1985-06-01

    Alpha-1 adrenergic receptors in surgically denervated rat vas deferens were studied using radioligand binding assays of (/sup 125/I) BE 2254 ((/sup 125/I)BE) and contraction measurements. Scatchard analysis of saturation isotherms of specific (/sup 125/I)BE binding showed no change in the affinity or density of binding sites 4, 7 or 14 days after denervation of rat vas deferens. The potency of norepinephrine in inhibiting specific (/sup 125/I)BE binding was also unchanged 7 days after denervation of vas deferens. The potency of phenylephrine in causing contractions in vitro did not change 4, 7 or 14 days after denervation of vas deferens; however, there was a significant increase in the maximum contractile response to phenylephrine at all time points. After partial inactivation of alpha-1 adrenergic receptors in vitro with phenoxybenzamine, there was an equivalent reduction in the number of (/sup 125/I)BE binding sites in the control and 14-day denervated vas deferens. The equilibrium dissociation constants calculated from contractile measurements for norepinephrine were the same in the control and denervated tissues. However, there was a 2.2-fold increase in contractile sensitivity to norepinephrine 14 days after denervation and a 3.6-fold increase in contractile sensitivity to methacholine 7 days after denervation.

  7. Lipoprotein binding and endosomal itinerary of the low density lipoprotein receptor-related protein in rat liver.

    PubMed Central

    Lund, H; Takahashi, K; Hamilton, R L; Havel, R J

    1989-01-01

    The high affinity of 45Ca binding to the low density lipoprotein receptor (LDL-R) and the LDL-R-related protein (LRP) was utilized to study the subcellular distribution of these two proteins in rat liver. Like the LDL-R, LRP was manyfold enriched in rat liver endosomal membranes with a relative distribution in early and late endosomal compartments consistent with recycling between endosomes and the cell surface. The high concentration of LRP in hepatic endosomal membranes greatly facilitated demonstration of Ca-dependent binding of apolipoprotein E- and B-containing lipoproteins in ligand blots. LRP was severalfold more abundant than the LDL-R in hepatic parenchymal cells, showed extensive degradation in hepatic endosomes, and was found in high concentrations in the Golgi apparatus and endoplasmic reticulum. These data suggest a high rate of synthesis of LRP that appeared to be unaffected by treatment of rats with estradiol. The repeating cysteine-rich A-motif found in the ligand-binding domain of LRP appeared to be responsible for Ca binding by LRP, LDL-R, and complement factor C9 and accounted for immunological cross-reactivity among these proteins. Weaker ligand-blotting properties and an extraordinary susceptibility to proteolysis most likely contribute to the difficulty of detecting LRP in conventional assays for lipoprotein receptors. Our data suggest an extensive proteolytic processing of this protein and are consistent with a functional role of LRP in lipoprotein metabolism. Images PMID:2594771

  8. The Role of Surface Receptor Density in Surface-Initiated Polymerizations for Cancer Cell Isolation.

    PubMed

    Lilly, Jacob L; Berron, Brad J

    2016-06-01

    Fluid biopsies potentially offer a minimally invasive alternative to traditional tissue biopsies for the continual monitoring of metastatic cancer. Current established technologies for isolating circulating tumor cells (CTCs) suffer from poor purity and yield and require fixatives that preclude the collection of viable cells for longitudinal analyses of biological function. Antigen specific lysis (ASL) is a rapid, high-purity method of cell isolation based on targeted protective coatings on antigen-presenting cells and lysis depletion of unprotected antigen-negative cells. In ASL, photoinitiators are specifically labeled on cell surfaces that enable subsequent surface-initiated polymerization. Critically, the significant determinants of process yield have yet to be investigated for this emerging technology. In this work, we show that the labeling density of photoinitiators is strongly correlated with the yield of intact cells during ASL by flow cytometry analysis. Results suggest ASL is capable of delivering ∼25% of targeted cells after isolation using traditional antibody labeling approaches. Monomer formulations of two molecular weights of PEG-diacrylate (Mn ∼ 575 and 3500) are examined. The gelation response during ASL polymerization is also investigated via protein microarray analogues on planar glass. Finally, a density threshold of photoinitiator labeling required for protection during lysis is determined for both monomer formulations. These results indicate ASL is a promising technology for high yield CTC isolation for rare-cell function assays and fluid biopsies. PMID:27206735

  9. Elucidating the structures and cooperative binding mechanism of cesium salts to the multitopic ion-pair receptor through density functional theory calculations.

    PubMed

    Sadhu, Biswajit; Sundararajan, Mahesh; Velmurugan, Gunasekaran; Venuvanalingam, Ponnambalam

    2015-09-21

    Designing new and innovative receptors for the selective binding of radionuclides is central to nuclear waste management processes. Recently, a new multi-topic ion-pair receptor was reported which binds a variety of cesium salts. Due to the large size of the receptor, quantum chemical calculations on the full ion-pair receptors are restricted, thus the binding mechanisms are not well understood at the molecular level. We have assessed the binding strengths of various cesium salts to the recently synthesized multi-topic ion-pair receptor molecule using density functional theory based calculations. Our calculations predict that the binding of cesium salts to the receptor predominantly occurs via the cooperative binding mechanism. Cesium and the anion synergistically assist each other to bind favorably inside the receptor. Energy decomposition analysis on the ion-pair complexes shows that the Cs salts are bound to the receptor mainly through electrostatic interactions with small contribution from covalent interactions for large ionic radius anions. Further, QTAIM analysis characterizes the importance of different inter-molecular interactions between the ions and the receptor inside the ion-pair complexes. The role of the crystallographic solvent molecule contributes significantly by ~10 kcal mol(-1) to the overall binding affinities which is quite significant. Further, unlike the recent molecular mechanics (MM) calculations, our calculated binding affinity trends for various Cs ion-pair complexes (CsF, CsCl and CsNO3) are now in excellent agreement with the experimental binding affinity trends. PMID:26227949

  10. Effect of alcohol on hepatic receptor of high density lipoproteins (HDL)

    SciTech Connect

    Lin, R.C.; Miller, B.M. V.A. Medical Center, Indianapolis, IN )

    1991-03-11

    Moderate alcohol intake has been shown to increase HDL cholesterol and proteins. The seemingly protective effect' of moderate alcohol drinking against cardiovascular diseases has been attributed to an increase in serum HDL. In this study, the authors show that a receptor for HDL is present in rat liver. Rat liver membrane was prepared by stepwise ultracentrifugation. Apo Al was iodinated using {sup 125}I-NaI and IODO-beads. HDL was labeled by incubating with {sup 125}I-apo Al then refloated be centrifugation. Binding of {sup 125}I-HDL to rat liver membrane reached equilibrium by 2-3 h and was saturable at 37C. The binding was inhibited 80% by excess unlabeled HDL, but was inhibited only 25% by excess LDL. It could also be inhibited by preincubating HDL with anti-apo Al or anti-apo E antisera but not with anti-apo AIV or control sera. The binding affinity of HDL to the liver membrane of rats fed alcohol for 5 wk was 50% that of their pair-fed controls. Thus a decrease in the binding of HDL to liver membrane due to alcohol-drinking may result in a slower clearance of HDL by the liver and consequently a higher HDL concentration in the serum.

  11. Serotonin acts through 5-HT1 and 5-HT2 receptors to exert biphasic actions on GnRH neuron excitability in the mouse.

    PubMed

    Bhattarai, Janardhan P; Roa, Juan; Herbison, Allan E; Han, Seong Kyu

    2014-02-01

    The effect of serotonin (5-HT) on the electrical excitability of GnRH neurons was examined using gramicidin perforated-patch electrophysiology in transgenic GnRH-green fluorescent protein mice. In diestrous female, the predominant effect of 5-HT was inhibition (70%) with 50% of these cells also exhibiting a late-onset excitation. Responses were dose dependent (EC(50) = 1.2μM) and persisted in the presence of amino acid receptor antagonists and tetrodotoxin, indicating a predominant postsynaptic action of 5-HT. Studies in neonatal, juvenile, peripubertal, and adult mice revealed that 5-HT exerted less potent responses from GnRH neurons with advancing postnatal age in both sexes. In adult male mice, 5-HT exerted less potent hyperpolarizing responses with more excitations compared with females. In addition, adult proestrous female GnRH neurons exhibited reduced inhibition and a complete absence of biphasic hyperpolarization-excitation responses. Studies using 5-HT receptor antagonists demonstrated that the activation of 5-HT(1A) receptors mediated the inhibitory responses, whereas the excitation was mediated by the activation of 5-HT(2A) receptors. The 5-HT-mediated hyperpolarization involved both potassium channels and adenylate cyclase activation, whereas the 5-HT excitation was dependent on protein kinase C. The effects of exogenous 5-HT were replicated using fluoxetine, which enhances endogenous 5-HT levels. These studies demonstrate that 5-HT exerts a biphasic action on most GnRH neurons whereby a fast 5HT(1A)-mediated inhibition occurs alongside a slow 5-HT(2A) excitation. The balance of 5-HT-evoked inhibition vs excitation is developmentally regulated, sexually differentiated, and variable across the estrous cycle and may play a role in regulation of hypothalamic-pituitary-gonadal axis throughout postnatal development.

  12. Quantitative autoradiographic analysis of /sup 125/I-pindolol binding in Fischer 344 rat brain: changes in beta-adrenergic receptor density with aging

    SciTech Connect

    Miller, J.A.; Zahniser, N.R.

    1988-05-01

    Age-related changes in beta-adrenergic receptor density in Fischer 344 rat brain were examined using in vitro /sup 125/I-pindolol (IPIN) binding and quantitative autoradiographic analysis. Localized protein concentrations were determined using a new quantitative histological technique, and these were used to normalize the densities of receptors. Saturation binding studies in brain sections revealed 40-50% decreases in beta-adrenergic receptor density in the thalamus of 23-25-month-old and the cerebellum and brainstem of both 18-19-month-old and 23-25-month-old compared to 4-6-month-old rats. The loss of cerebellar beta-adrenergic receptors may be correlated with reports of deficits in sensitivity to beta-adrenergic-mediated transmission in the cerebellum of aged rats. No changes in specific IPIN binding with age were observed in rat cortex or hippocampus. In all areas examined no age-related differences were observed in receptor affinity. No changes in protein concentration were found in any of the areas examined in the different aged animals. These results demonstrate a region-specific loss of beta-adrenergic receptors with age in the brain of Fischer 344 rats.

  13. Expression of lectin-like oxidized low density lipoprotein receptor-1 in human and murine macrophages: upregulated expression by TNF-alpha.

    PubMed

    Moriwaki, H; Kume, N; Kataoka, H; Murase, T; Nishi, E; Sawamura, T; Masaki, T; Kita, T

    1998-11-27

    Uptake of oxidized low density lipoprotein (Ox-LDL) and subsequent foam cell transformation have been implicated in early atherogenesis. Although multiple molecules, including class A and B scavenger receptors, have been identified as Ox-LDL receptors, additional receptors may also be involved in this process. Here, we provide evidence that lectin-like Ox-LDL receptor-1 (LOX-1), a novel Ox-LDL receptor initially identified in vascular endothelial cells, is also expressed in macrophages in humans and mice. Expression of LOX-1 can be induced after macrophage-like differentiation in vitro in human peripheral blood monocytes and the related cell line THP-1 cells. Furthermore, LOX-1 expression can also be detected in resident peritoneal macrophages, and can be upregulated by an inflammatory cytokine TNF-alpha. These results suggest that LOX-1 in macrophages may play an important role in Ox-LDL uptake and subsequent foam cell formation in this cell type.

  14. Antagonism of Secreted PCSK9 Increases Low Density Lipoprotein Receptor Expression in HepG2 Cells

    SciTech Connect

    McNutt, Markey C.; Kwon, Hyock Joo; Chen, Chiyuan; Chen, Justin R.; Horton, Jay D.; Lagace, Thomas A.

    2009-07-10

    PCSK9 is a secreted protein that degrades low density lipoprotein receptors (LDLRs) in liver by binding to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. It is not known whether PCSK9 causes degradation of LDLRs within the secretory pathway or following secretion and reuptake via endocytosis. Here we show that a mutation in the LDLR EGF-A domain associated with familial hypercholesterolemia, H306Y, results in increased sensitivity to exogenous PCSK9-mediated cellular degradation because of enhanced PCSK9 binding affinity. The crystal structure of the PCSK9-EGF-A(H306Y) complex shows that Tyr-306 forms a hydrogen bond with Asp-374 in PCSK9 at neutral pH, which strengthens the interaction with PCSK9. To block secreted PCSK9 activity, LDLR (H306Y) subfragments were added to the medium of HepG2 cells stably overexpressing wild-type PCSK9 or gain-of-function PCSK9 mutants associated with hypercholesterolemia (D374Y or S127R). These subfragments blocked secreted PCSK9 binding to cell surface LDLRs and resulted in the recovery of LDLR levels to those of control cells. We conclude that PCSK9 acts primarily as a secreted factor to cause LDLR degradation. These studies support the concept that pharmacological inhibition of the PCSK9-LDLR interaction extracellularly will increase hepatic LDLR expression and lower plasma low density lipoprotein levels.

  15. Magnetic Resonance Imaging Detection of Tumor Cells by Targeting Low-Density Lipoprotein Receptors with Gd-Loaded Low-Density Lipoprotein Particles1

    PubMed Central

    Crich, Simonetta Geninatti; Lanzardo, Stefania; Alberti, Diego; Belfiore, Simona; Ciampa, Anna; Giovenzana, Giovanni B; Lovazzano, Clara; Pagliarin, Roberto; Aime, Silvio

    2007-01-01

    Gd-DO3A-diph and Gd-AAZTAC17 are lipophilic magnetic resonance imaging (MRI) agents that display high affinity for low-density lipoprotein (LDL) particles. However, on binding to LDL, Gd-DO3A-diph shows a decreased hydration that results in a lower enhancement of water proton relaxation rate. Conversely, Gd-AAZTAC17 displays a strong relaxation enhancement at the imaging fields. Each LDL particle can load up to 100 and 400 UNITS of Gd-DO3A-diph and Gd-AAZTAC17, respectively. Their LDL adducts are taken up by human hepatoblastoma G2 (HepG2) and melanoma B16 tumor cells when added to the incubation medium. T1 measurements of the labeled cells indicate that Gd-AAZTAC17 is significantly more efficient than Gd-DO3A-diph. Furthermore, it has been found that HepG2 hepatoma cells can internalize higher amounts of Gd-AAZTAC17 than B16 cells and the involvement of LDL receptors (LDLRs) has been demonstrated in competition assays with free LDL. Gd-AAZTAC17/LDL adduct proved to be an efficient probe in the magnetic resonance (MR) visualization of subcutaneous tumors in animal models obtained by injecting B16 melanoma cells into the right flank of mice. Finally, confocal microscopy validation of the distribution of LDL-based probes in the tumor has been obtained by doping the Gd-AAZTAC17/LDL adduct with a fluorescent phospholipid moiety. PMID:18084612

  16. Lipoprotein receptors in copper-deficient rats: high density lipoprotein binding to liver membranes

    SciTech Connect

    Hassel, C.A.; Lei, K.Y.; Marchello, J.A.

    1986-03-05

    In copper-deficient rats, the observed hyperlipoproteinemia was mainly due to the elevation in high density lipoproteins (HDL). This study was designed to determine whether an impairment in the binding of HDL to liver membrane is responsible for the hyperlipoproteinemia. Sixty male Sprague-Dawley rats were randomly divided into 2 treatments, namely copper (Cu) deficient and adequate (less than 1 and 8 mg Cu/kg of diet). After 8 weeks, plasma, heart and liver tissues were obtained. Reduction in liver Cu content and elevation in heart to body weight ratio and plasma cholesterol confirmed that rats fed the test diet were Cu-deficient. Plasma HDL isolated from both Cu-deficient and control rats were iodinated and bound to liver membranes prepared from rats of each treatment. Binding of /sup 125/I-HDL was competitively inhibited by unlabelled rat HDL from both treatments, but not by human LDL. Scatchard analysis of specific binding data showed that maximal /sup 125/I-HDL binding (per mg membrane protein) to membranes prepared from Cu-deficient rats was not lower than controls. Furthermore, the amount of /sup 125/I-HDL from deficient rats specifically bound to liver membranes prepared from either treatment was not less than the amount of /sup 125/I-HDL from control rats bound to the same membranes. The data suggest that the hyperlipoproteinemia in Cu-deficient rats may not have resulted from a decrease in the number of hepatic HDL binding sites.

  17. ANTIDEPRESSANT-LIKE EFFECTS OF LOW KETAMINE DOSE IS ASSOCIATED WITH INCREASED HIPPOCAMPAL AMPA/NMDA RECEPTOR DENSITY RATIO IN FEMALE WISTAR-KYOTO RATS

    PubMed Central

    Tizabi, Yousef; Bhatti, Babur H; Manaye, Kebreten F; Das, Jharna R; Akinfiresoye, Luli

    2012-01-01

    Preclinical as well as limited clinical studies indicate that ketamine, a non-competitive glutamate NMDA receptor antagonist, may exert a quick and prolonged antidepressant effect. It has been postulated that ketamine action is due to inhibition of NMDA and stimulation of AMPA receptors. Here, we sought to determine whether ketamine would exert antidepressant effects in Wistar-Kyoto (WKY) rats, a putative animal model of depression and whether this effect would be associated with changes in AMPA/NMDA receptor densities in the hippocampus. Adult female WKY rats and their control Wistar rats were subjected to acute and chronic ketamine doses and their locomotor activity (LMA) and immobility in the forced swim test (FST) were evaluated. Hippocampal AMPA and NMDA receptor densities were also measured following a chronic ketamine dose. Ketamine, both acutely (0.5–5.0 mg/kg ip) and chronically (0.5–2.5 mg/kg daily for 10 days) resulted in a dose-dependent and prolonged decrease in immobility in the FST in WKY rats only, suggesting an antidepressant-like effect in this model. Chronic treatment with an effective dose of ketamine also resulted in an increase in AMPA/NMDA receptor density ratio in the hippocampus of WKY rats. LMA was not affected by any ketamine treatment in either strain. These results indicate a rapid and lasting antidepressant-like effect of a low ketamine dose in WKY rat model of depression. Moreover, the increase in AMPA/NMDA receptor density in hippocampus could be a contributory factor to behavioral effects of ketamine. These findings suggest potential therapeutic benefit in simultaneous reduction of central NMDA and elevation of AMPA receptor function in treatment of depression. PMID:22521815

  18. Characterization of the 5-hydroxytryptamine receptors mediating contraction in the pig isolated intravesical ureter

    PubMed Central

    Hernández, Medardo; Barahona, María Victoria; Simonsen, Ulf; Recio, Paz; Rivera, Luis; Martínez, Ana Cristina; García-Sacristán, Albino; Orensanz, Luis M; Prieto, Dolores

    2003-01-01

    This study was designed to investigate the effect of 5-hydroxytryptamine (5-HT) and to characterize the 5-HT receptors involved in 5-HT responses in the pig intravesical ureter. 5-HT (0.01–10 μM) concentration-dependently increased the tone of intravesical ureteral strips, whereas the increases in phasic contractions were concentration-independent. The 5-HT2 receptor agonist α-methyl 5-HT, mimicked the effect on tone whereas weak or no response was obtained with 5-CT, 8-OH-DPAT, m-chlorophenylbiguanide and RS 67333, 5-HT1, 5-HT1A, 5-HT3 and 5-HT4 receptor agonists, respectively. 5-HT did not induce relaxation of U46619-contracted ureteral preparations. Pargyline (100 μM), a monoaminooxidase A/B activity inhibitor, produced leftward displacements of the concentration-response curves for 5-HT. 5-HT-induced tone was reduced by the 5-HT2 and 5-HT2A receptor antagonists ritanserine (0.1 μM) and spiperone (0.2 μM), respectively. However, 5-HT contraction was not antagonized by cyanopindolol (2 μM), SDZ–SER 082 (1 μM), Y-25130 (1 μM) and GR 113808 (0.1 μM), which are respectively, 5-HT1A/1B, 5-HT2B/2C, 5-HT3, and 5-HT4 selective receptor antagonists. Removal of the urothelium did not modify 5-HT-induced contractions. Blockade of neuronal voltage-activated sodium channels, α-adrenergic receptors and adrenergic neurotransmission with tetrodotoxin (1 μM), phentolamine (0.3 μM) and guanethidine (10 μM), respectively, reduced the contractions to 5-HT. However, physostigmine (1 μM), atropine (0.1 μM) and suramin (30 μM), inhibitors of cholinesterase activity, muscarinic- and purinergic P2-receptors, respectively, failed to modify the contractions to 5-HT. These results suggest that 5-HT increases the tone of the pig intravesical ureter through 5-HT2A receptors located at the smooth muscle. Part of the 5-HT contraction is indirectly mediated via noradrenaline release from sympathetic nerves. PMID:12522083

  19. Structure and chromosomal assignment of the human lectin-like oxidized low-density-lipoprotein receptor-1 (LOX-1) gene.

    PubMed Central

    Aoyama, T; Sawamura, T; Furutani, Y; Matsuoka, R; Yoshida, M C; Fujiwara, H; Masaki, T

    1999-01-01

    We have reported the cDNA cloning of a modified low-density-lipoprotein (LDL) receptor, designated lectin-like oxidized LDL receptor-1 (LOX-1), which is postulated to be involved in endothelial dysfunction and the pathogenesis of atherosclerosis. Here, we determined the organization of the human LOX-1 gene, including the 5'-regulatory region. The 5'-regulatory region contained several potential cis-regulatory elements, such as GATA-2 binding element, c-ets-1 binding element, 12-O-tetradecanoylphorbol 13-acetate-responsive element and shear-stress-responsive elements, which may mediate the endothelium-specific and inducible expression of LOX-1. The major transcription-initiation site was found to be located 29 nucleotides downstream of the TATA box and 61 nucleotides upstream from the translation-initiation codon. The minor initiation site was found to be 5 bp downstream from the major site. Most of the promoter activity of the LOX-1 gene was ascribed to the region (-150 to -90) containing the GC and CAAT boxes. The coding sequence was divided into 6 exons by 5 introns. The first 3 exons corresponded to the different functional domains of the protein (cytoplasmic, transmembrane and neck domains), and the residual 3 exons encoded the carbohydrate-recognition domain similar to the case of other C-type lectin genes. The LOX-1 gene was a single-copy gene and assigned to the p12.3-p13.2 region of chromosome 12. Since the locus for a familial hypertension has been mapped to the overlapping region, LOX-1 might be the gene responsible for the hypertension. PMID:10085242

  20. Dietary herring improves plasma lipid profiles and reduces atherosclerosis in obese low-density lipoprotein receptor-deficient mice.

    PubMed

    Gabrielsson, Britt G; Wikström, Johannes; Jakubowicz, Robert; Marmon, Sofia K; Carlsson, Nils-Gunnar; Jansson, Nina; Gan, Li-Ming; Undeland, Ingrid; Lönn, Malin; Holmäng, Agneta; Sandberg, Ann-Sofie

    2012-03-01

    Diet is a significant modifiable risk factor for cardiovascular disease and high fish intake has been associated with vascular health in population studies. However, intervention studies have been inconclusive. In this study, male low-density lipoprotein receptor-deficient mice were given 16-week high fat/high sucrose diets, supplemented with either minced herring fillets or minced beef. The diets were matched in total fat and cholesterol content; taurine content and fatty acid composition was analysed. Body weights were recorded throughout the study; plasma lipids were analysed at week 8 and 16. Body composition and adipocyte size were evaluated at study end. Atherosclerosis was evaluated at week 12 (ultrasound) and at termination (en face histology). Herring-fed mice had a higher proportion of long-chain n-3 polyunsaturated fatty acids in the hepatic triacylglycerides (TAG) and phospholipid fractions. The herring-fed mice had increased body weight (P=0.007), and reduced epididymal adipocyte size (P=0.009), despite similar food intake and body composition as the beef-fed mice. The herring-fed mice had lower plasma TAG and very-low-density lipoprotein (VLDL)-cholesterol concentrations throughout the study (TAG; P=0.0012 and 0.004, VLDL-cholesterol; P=0.006 and 0.041, week 8 and 16, respectively). At week 16, the herring-fed had higher plasma concentrations of HDL-cholesterol (P=0.004) and less atherosclerotic lesions in the aortic arch (P=0.007) compared with the beef-fed mice. In conclusion, dietary herring in comparison to beef markedly improved vascular health in this mouse model, suggesting that herring provides an added value beyond its content of macronutrients.

  1. Tissue-type plasminogen activator suppresses activated stellate cells through low-density lipoprotein receptor-related protein 1.

    PubMed

    Kang, Liang-I; Isse, Kumiko; Koral, Kelly; Bowen, William C; Muratoglu, Selen; Strickland, Dudley K; Michalopoulos, George K; Mars, Wendy M

    2015-10-01

    Hepatic stellate cell (HSC) activation and trans-differentiation into myofibroblast (MFB)-like cells is key for fibrogenesis after liver injury and a potential therapeutic target. Recent studies demonstrated that low-density lipoprotein receptor-related protein 1 (LRP1)-dependent signaling by tissue-type plasminogen activator (t-PA) is a pro-fibrotic regulator of the MFB phenotype in kidney. This study investigated whether LRP1 signaling by t-PA is also relevant to HSC activation following injury. Primary and immortalized rat HSCs were treated with t-PA and assayed by western blot, MTT, and TUNEL. In vitro results were then verified using an in vivo, acute carbon tetrachloride (CCl4) injury model that examined the phenotype and recovery kinetics of MFBs from wild-type animals vs mice with a global (t-PA) or HSC-targeted (LRP1) deletion. In vitro, in contrast to kidney MFBs, exogenous, proteolytically inactive t-PA suppressed, rather than induced, activation markers in HSCs following phosphorylation of LRP1. This process was mediated by LRP1 as inhibition of t-PA binding to LRP1 blocked the effects of t-PA. In vivo, following acute injury, phosphorylation of LRP1 on activated HSCs occurred immediately prior to their disappearance. Mice lacking t-PA or LRP1 retained higher densities of activated HSCs for a longer time period compared with control mice after injury cessation. Hence, t-PA, an FDA-approved drug, contributes to the suppression of activated HSCs following injury repair via signaling through LRP1. This renders t-PA a potential target for exploitation in treating patients with fibrosis.

  2. Lack of association of vitamin D receptor BsmI gene polymorphism with bone mineral density in Spanish postmenopausal women

    PubMed Central

    Rodriguez-Velasco, Francisco J.; Vera, Vicente; Lavado-Garcia, Jesus M.; Fernandez, Pilar

    2015-01-01

    Osteoporosis is a polygenic disorder that is determined by the effects of several genes, each with relatively modest effects on bone mass. The aim of this study was to determine whether the vitamin D receptor single nucleotide polymorphism BsmI is associated with bone mineral density (BMD) in Spanish postmenopausal women. A total of 210 unrelated healthy postmenopausal women aged 60 ± 8 years were genotyped using TaqMan® SNP Genotyping Assays. Lumbar and femoral BMD were determined by dual-energy X-ray absorptiometry (DEXA). Daily calcium and vitamin D intake were determined by a food questionnaire. No differences were found in the femoral neck, trochanter, Ward’s Triangle, L2, L3, L4, L2-L4, or between the femoral neck and total hip BMD after further adjustment for potential confounding factors (P > 0.05) (age, BMI, years since menopause and daily calcium intake). The BsmI polymorphism in the VDR gene was not associated with BMD in Spanish postmenopausal women. PMID:26157644

  3. Dysregulation of the Low-Density Lipoprotein Receptor Pathway Is Involved in Lipid Disorder-Mediated Organ Injury

    PubMed Central

    Zhang, Yang; Ma, Kun Ling; Ruan, Xiong Zhong; Liu, Bi Cheng

    2016-01-01

    The low-density lipoprotein receptor (LDLR) pathway is a negative feedback system that plays important roles in the regulation of plasma and intracellular cholesterol homeostasis. To maintain a cholesterol homeostasis, LDLR expression is tightly regulated by sterol regulatory element-binding protein-2 (SREBP-2) and SREBP cleavage-activating protein (SCAP) in transcriptional level and by proprotein convertase subtilisin/kexin type 9 (PCSK9) in posttranscriptional level. The dysregulation of LDLR expression results in abnormal lipid accumulation in cells and tissues, such as vascular smooth muscle cells, hepatic cells, renal mesangial cells, renal tubular cells and podocytes. It has been demonstrated that inflammation, renin-angiotensin system (RAS) activation, and hyperglycemia induce the disruption of LDLR pathway, which might contribute to lipid disorder-mediated organ injury (atherosclerosis, non-alcoholic fatty liver disease, kidney fibrosis, etc). The mammalian target of rapamycin (mTOR) pathway is a critical mediator in the disruption of LDLR pathway caused by pathogenic factors. The mTOR complex1 activation upregulates LDLR expression at the transcriptional and posttranscriptional levels, consequently resulting in lipid deposition. This paper mainly reviews the mechanisms for the dysregulation of LDLR pathway and its roles in lipid disorder-mediated organ injury under various pathogenic conditions. Understanding these mechanisms leading to the abnormality of LDLR expression contributes to find potential new drug targets in lipid disorder-mediated diseases. PMID:27019638

  4. Adipose tissue deficiency results in severe hyperlipidemia and atherosclerosis in the low-density lipoprotein receptor knockout mice.

    PubMed

    Wang, Mengyu; Gao, Mingming; Liao, Jiawei; Qi, Yanfei; Du, Ximing; Wang, Yuhui; Li, Ling; Liu, George; Yang, Hongyuan

    2016-05-01

    Adipose tissue can store over 50% of whole-body cholesterol; however, the physiological role of adipose tissue in cholesterol metabolism and atherogenesis has not been directly assessed. Here, we examined lipoprotein metabolism and atherogenesis in a unique mouse model of severe lipodystrophy: the Seipin(-/-) mice, and also in mice deficient in both low-density lipoprotein receptor (Ldlr) and Seipin: the Ldlr(-/-)Seipin(-/-) mice. Plasma cholesterol was moderately increased in the Seipin(-/-) mice when fed an atherogenic diet. Strikingly, plasma cholesterol reached ~6000 mg/dl in the Seipin(-/-)Ldlr(-/-) mice on an atherogenic diet, as compared to ~1000 mg/dl in the Ldlr(-/-) mice on the same diet. The Seipin(-/-)Ldlr(-/-) mice also developed spontaneous atherosclerosis on chow diet and severe atherosclerosis on an atherogenic diet. Rosiglitazone treatment significantly reduced the hypercholesterolemia of the Seipin(-/-)Ldlr(-/-) mice, and also alleviated the severity of atherosclerosis. Our results provide direct evidence, for the first time, that the adipose tissue plays a critical role in the clearance of plasma cholesterol. Our results also reveal a previously unappreciated strong link between adipose tissue and LDLR in plasma cholesterol metabolism.

  5. Ultrasound-targeted microbubble destruction improves the low density lipoprotein receptor gene expression in HepG{sub 2} cells

    SciTech Connect

    Guo Dongping; Li Xiaoyu; Sun, Ping; Tang Yibo; Chen Xiuying; Chen Qi; Fan Leming . E-mail: lmfan@njmu.edu.cn; Zang Bin; Shao Lizheng; Li Xiaorong

    2006-05-05

    Ultrasound-targeted microbubble destruction had been employed in gene delivery and promised great potential. Liver has unique features that make it attractive for gene therapy. However, it poses formidable obstacles to hepatocyte-specific gene delivery. This study was designed to test the efficiency of therapeutic gene transfer and expression mediated by ultrasound/microbubble strategy in HepG{sub 2} cell line. Air-filled albumin microbubbles were prepared and mixed with plasmid DNA encoding low density lipoprotein receptor (LDLR) and green fluorescent protein. The mixture of the DNA and microbubbles was administer to cultured HepG{sub 2} cells under variable ultrasound conditions. Transfection rate of the transferred gene and cell viability were assessed by FACS analysis, confocal laser scanning microscopy, Western blot analysis and Trypan blue staining. The result demonstrated that microbubbles with ultrasound irradiation can significantly elevate exogenous LDLR gene expression and the expressed LDLRs were functional and active to uptake their ligands. We conclude that ultrasound-targeted microbubble destruction has the potential to promote safe and efficient LDLR gene transfer into hepatocytes. With further refinement, it may represent an effective nonviral avenue of gene therapy for liver-involved genetic diseases.

  6. Characterization of a receptor for oxidized low-density lipoproteins on rat Kupffer cells: similarity to macrosialin.

    PubMed Central

    Van Velzen, A G; Da Silva, R P; Gordon, S; Van Berkel, T J

    1997-01-01

    Rat liver Kupffer cell membranes contain a protein that recognizes specifically oxidized low-density lipoproteins (oxLDL). Visualization after blotting under reducing conditions indicates that the receptor is a monomeric protein, with an estimated molecular mass of 115-120 kDa. N-Glycosidase F and endoglycosidase F treatment resulted in a fall in estimated molecular mass of 24 and 11 kDa respectively, whereas O-glycosidase was ineffective. No effect on the extent of interaction with oxLDL was noticed, suggesting that glycans are not essential for ligand recognition. Using a polyclonal antibody to mouse macrosialin, we visualized macrosialin on blot, and compared this glycoprotein with the oxLDL-binding protein. It appears that the two glycoproteins have a similar molecular mass and are comparably affected by treatment with the different glycosidases. Incubation with trypsin resulted in a reduction in the estimated molecular mass of about 25 kDa for both the oxLDL-binding protein and macrosialin. These results indicate that the oxLDL-binding protein and macrosialin are identical, suggesting a role for macrosialin in modified LDL catabolism. PMID:9065757

  7. Evidence of association of vitamin D receptor Apa I gene polymorphism with bone mineral density in postmenopausal women with osteoporosis.

    PubMed

    Dundar, Umit; Solak, Mustafa; Kavuncu, Vural; Ozdemir, Mujgan; Cakir, Tuncay; Yildiz, Handan; Evcik, Deniz

    2009-10-01

    The vitamin D receptor (VDR) was the first candidate gene to be studied in relation to osteoporosis, and most attention has focused on polymorphisms situated near the 3' flank of VDR. The aim of this study was to investigate the association about VDR gene Apa I polymorphism with bone mineral density (BMD) in postmenopausal women with osteoporosis. We studied a total of 136 postmenopausal women with a mean age of 56.36 +/- 10.29 years. Among them, a total of 75 had osteoporosis, 37 had osteopenia, and 24 had normal BMD. Venous blood samples were obtained for evaluation of bone metabolism and genotyping. The VDR Apa I genotype was determined by polymerase chain reaction-restriction fragment length polymorphism. BMDs at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry. Postmenopausal women with aa genotype had significantly lower BMD values (grams per centimeter square) at lumbar spines compared to persons with AA genotype. Also, postmenopausal women with AA genotype had significantly higher serum Ca level than the subjects with aa genotype. In conclusion, our result may indicate that VDR Apa I gene polymorphism may be responsible for a important part of the heritable component of lumbar spine BMD in postmenopausal women, possibly related to impaired calcium absorption from the bowel.

  8. Dopamine receptor D1 and postsynaptic density gene variants associate with opiate abuse and striatal expression levels.

    PubMed

    Jacobs, M M; Ökvist, A; Horvath, M; Keller, E; Bannon, M J; Morgello, S; Hurd, Y L

    2013-11-01

    Opioid drugs are highly addictive and their abuse has a strong genetic load. Dopamine-glutamate interactions are hypothesized to be important for regulating neural systems central for addiction vulnerability. Balanced dopamine-glutamate interaction is mediated through several functional associations, including a physical link between discs, large homolog 4 (Drosophila) (DLG4, PSD-95) and dopamine receptor 1 (DRD1) within the postsynaptic density to regulate DRD1 trafficking. To address whether genetic associations with heroin abuse exist in relation to dopamine and glutamate and their potential interactions, we evaluated single-nucleotide polymorphisms of key genes within these systems in three populations of opiate abusers and controls, totaling 489 individuals from Europe and the United States. Despite significant differences in racial makeup of the separate samples, polymorphisms of DRD1 and DLG4 were found to be associated with opiate abuse. In addition, a strong gene-gene interaction between homer 1 homolog (Drosophila) (HOMER1) and DRD1 was predicted to occur in Caucasian subjects. This interaction was further analyzed by evaluating DRD1 genotype in relation to HOMER1b/c protein expression in postmortem tissue from a subset of Caucasian subjects. DRD1 rs265973 genotype correlated with HOMER1b/c levels in the striatum, but not cortex or amygdala; the correlation was inversed in opiate abusers as compared with controls. Cumulatively, these results support the hypothesis that there may be significant, genetically influenced interactions between glutamatergic and dopaminergic pathways in opiate abusers.

  9. Low density lipoprotein receptor-related protein 1 mediated endocytosis of β1-integrin influences cell adhesion and cell migration.

    PubMed

    Rabiej, Verena K; Pflanzner, Thorsten; Wagner, Timo; Goetze, Kristina; Storck, Steffen E; Eble, Johannes A; Weggen, Sascha; Mueller-Klieser, Wolfgang; Pietrzik, Claus U

    2016-01-01

    The low density lipoprotein receptor-related protein 1 (LRP1) has been shown to interact with β1-integrin and regulate its surface expression. LRP1 knock-out cells exhibit altered cytoskeleton organization and decreased cell migration. Here we demonstrate coupled endocytosis of LRP1 and β1-integrin and the involvement of the intracellular NPxY2 motif of LRP1 in this process. Mouse embryonic fibroblasts harboring a knock in replacement of the NPxY2 motif of LRP1 by a multiple alanine cassette (AAxA) showed elevated surface expression of β1-integrin and decreased β1-integrin internalization rates. As a consequence, cell spreading was altered and adhesion rates were increased in our cell model. Cells formed more focal adhesion complexes, whereby in vitro cell migration rates were decreased. Similar results could be observed in a corresponding mouse model, the C57Bl6 LRP1 NPxYxxL knock in mice, therefore, the biochemistry of cellular adhesion was altered in primary cortical neurons. In vivo cell migration experiments demonstrated a disturbance of neuroblast cell migration along the rostral migratory stream. In summary, our results indicate that LRP1 interacts with β1-integrin mediating integrin internalization and thus correlates with downstream signaling of β1-integrin such as focal adhesion dynamics. Consequently, the disturbance of this interaction resulted in a dysfunction in in vivo and in vitro cell adhesion and cell migration.

  10. Amino acid sequence and domain structure of entactin. Homology with epidermal growth factor precursor and low density lipoprotein receptor

    PubMed Central

    1988-01-01

    Entactin (nidogen), a 150-kD sulfated glycoprotein, is a major component of basement membranes and forms a highly stable noncovalent complex with laminin. The complete amino acid sequence of mouse entactin has been derived from sequencing of cDNA clones. The 5.9-kb cDNA contains a 3,735-bp open reading frame followed by a 3'- untranslated region of 2.2 kb. The open reading frame encodes a 1,245- residue polypeptide with an unglycosylated Mr of 136,500, a 28-residue signal peptide, two Asn-linked glycosylation sites, and two potential Ca2+-binding sites. Analysis of the deduced amino acid sequence predicts that the molecule consists of two globular domains of 70 and 36 kD separated by a cysteine-rich domain of 28 kD. The COOH-terminal globular domain shows homology to the EGF precursor and the low density lipoprotein receptor. Entactin contains six EGF-type cysteine-rich repeat units and one copy of a cysteine-repeat motif found in thyroglobulin. The Arg-Gly-Asp cell recognition sequence is present in one of the EGF-type repeats, and a synthetic peptide from the putative cell-binding site of entactin was found to promote the attachment of mouse mammary tumor cells. PMID:3264556

  11. Dopamine receptor D1 and post-synaptic density gene variants associate with opiate abuse and striatal expression levels

    PubMed Central

    Jacobs, Michelle M.; Ökvist, Anna; Horvath, Monika; Keller, Eva; Bannon, Michael J.; Morgello, Susan; Hurd, Yasmin L.

    2013-01-01

    Opioid drugs are highly addictive and their abuse has a strong genetic load. Dopamine-glutamate interactions are hypothesized to be important for regulating neural systems central for addiction vulnerability. Balanced dopamine-glutamate interaction is mediated through several functional associations, including a physical link between discs, large homolog 4 (Drosophila) (DLG4, PSD-95) and dopamine receptor 1 (DRD1) within the postsynaptic density to regulate DRD1 trafficking. To address whether genetic associations with heroin abuse exist in relation to dopamine and glutamate and their potential interactions, we evaluated single nucleotide polymorphisms of key genes within these systems in three populations of opiate abusers and controls, totaling 489 individuals from Europe and the USA. Despite significant differences in racial makeup of the separate samples, polymorphisms of DRD1 and DLG4 were found to be associated with opiate abuse. In addition, a strong gene-gene interaction between homer 1 homolog (Drosophila) (HOMER1) and DRD1 was predicted to occur in Caucasian subjects. This interaction was further analyzed by evaluating DRD1 genotype in relation to HOMER1b/c protein expression in postmortem tissue from a subset of Caucasian subjects. DRD1 rs265973 genotype correlated with HOMER1b/c levels in the striatum, but not cortex or amgydala; the correlation was inversed in opiate abusers as compared to controls. Cumulatively, these results support the hypothesis that there may be significant, genetically-influenced interactions between glutamatergic and dopaminergic pathways in opiate abusers. PMID:23044706

  12. Known vitamin D receptor polymorphisms are not associated with bone mineral density measures in pediatric Cushing disease

    PubMed Central

    Lodish, Maya B.; Mastroyannis, Spyridon A.; Sinaii, Ninet; Boikos, Sosipatros A.; Stratakis, Constantine A.

    2014-01-01

    Background Decreased bone mineral density (BMD) has been documented in adults with Cushing disease (CD), and allelic variants of the vitamin D receptor (VDR) gene have been associated with osteopenia. Genetic factors play an important role in bone accrual and its response to various diseases; among them, the most studied are the allelic variants of the VDR gene. There is debate as to whether or not described variants in the VDR gene have an effect on BMD. We previously investigated the Taq I and Apa I VDR alleles for an association with low BMD in women with depression and evidence of endogenous hypercortisolism. Methods In the current study, we sought to analyze whether BMD differences in patients with CD were associated with the Taq I and Apa I VDR allelotypes. Results The data showed lack of association between BMD and VDR polymorphisms. Conclusions This study suggests that the effect of endogenous hypercortisolism on bone in the context of CD is independent of VDR genotypes. PMID:22570981

  13. Mutations in the very low-density lipoprotein receptor VLDLR cause cerebellar hypoplasia and quadrupedal locomotion in humans

    PubMed Central

    Ozcelik, Tayfun; Akarsu, Nurten; Uz, Elif; Caglayan, Safak; Gulsuner, Suleyman; Onat, Onur Emre; Tan, Meliha; Tan, Uner

    2008-01-01

    Quadrupedal gait in humans, also known as Unertan syndrome, is a rare phenotype associated with dysarthric speech, mental retardation, and varying degrees of cerebrocerebellar hypoplasia. Four large consanguineous kindreds from Turkey manifest this phenotype. In two families (A and D), shared homozygosity among affected relatives mapped the trait to a 1.3-Mb region of chromosome 9p24. This genomic region includes the VLDLR gene, which encodes the very low-density lipoprotein receptor, a component of the reelin signaling pathway involved in neuroblast migration in the cerebral cortex and cerebellum. Sequence analysis of VLDLR revealed nonsense mutation R257X in family A and single-nucleotide deletion c2339delT in family D. Both these mutations are predicted to lead to truncated proteins lacking transmembrane and signaling domains. In two other families (B and C), the phenotype is not linked to chromosome 9p. Our data indicate that mutations in VLDLR impair cerebrocerebellar function, conferring in these families a dramatic influence on gait, and that hereditary disorders associated with quadrupedal gait in humans are genetically heterogeneous. PMID:18326629

  14. Low-Density Lipoprotein Receptor-Related Protein 6 (LRP6) Is a Novel Nutritional Therapeutic Target for Hyperlipidemia, Non-Alcoholic Fatty Liver Disease, and Atherosclerosis.

    PubMed

    Go, Gwang-woong

    2015-06-01

    Low-density lipoprotein receptor-related protein 6 (LRP6) is a member of the low-density lipoprotein receptor family and has a unique structure, which facilitates its multiple functions as a co-receptor for Wnt/β-catenin signaling and as a ligand receptor for endocytosis. The role LRP6 plays in metabolic regulation, specifically in the nutrient-sensing pathway, has recently garnered considerable interest. Patients carrying an LRP6 mutation exhibit elevated levels of LDL cholesterol, triglycerides, and fasting glucose, which cooperatively constitute the risk factors of metabolic syndrome and atherosclerosis. Since the discovery of this mutation, the general role of LRP6 in lipid homeostasis, glucose metabolism, and atherosclerosis has been thoroughly researched. These studies have demonstrated that LRP6 plays a role in LDL receptor-mediated LDL uptake. In addition, when the LRP6 mutant impaired Wnt-LRP6 signaling, hyperlipidemia, non-alcoholic fatty liver disease, and atherosclerosis developed. LRP6 regulates lipid homeostasis and body fat mass via the nutrient-sensing mechanistic target of the rapamycin (mTOR) pathway. Furthermore, the mutant LRP6 triggers atherosclerosis by activating platelet-derived growth factor (PDGF)-dependent vascular smooth muscle cell differentiation. This review highlights the exceptional opportunities to study the pathophysiologic contributions of LRP6 to metabolic syndrome and cardiovascular diseases, which implicate LRP6 as a latent regulator of lipid metabolism and a novel therapeutic target for nutritional intervention. PMID:26046396

  15. Substituted methcathinones differ in transporter and receptor interactions

    PubMed Central

    Eshleman, Amy J; Wolfrum, Katherine M; Hatfield, Meagan G; Johnson, Robert A; Murphy, Kevin V; Janowsky, Aaron

    2013-01-01

    The use of synthetic methcathinones, components of “bath salts,” is a world-wide health concern. These compounds, structurally similar to methamphetamine (METH) and 3,4-methylendioxymethamphetamine (MDMA), cause tachycardia, hallucinations and psychosis. We hypothesized that these potentially neurotoxic and abused compounds display differences in their transporter and receptor interactions as compared to amphetamine counterparts. 3,4-Methylenedioxypyrovalerone and naphyrone had high affinity for radioligand binding sites on recombinant human dopamine (hDAT), serotonin (hSERT) and norepinephrine (hNET) transporters, potently inhibited [3H]neurotransmitter uptake, and, like cocaine, did not induce transporter-mediated release. Butylone was a lower affinity uptake inhibitor. In contrast, 4-fluoromethcathinone, mephedrone and methylone had higher inhibitory potency at uptake compared to binding and generally induced release of preloaded [3H]neurotransmitter from hDAT, hSERT and hNET (highest potency at hNET), and thus are transporter substrates, similar to METH and MDMA. At hNET, 4-fluoromethcathinone was a more efficacious releaser than METH. These substituted methcathinones had low uptake inhibitory potency and low efficacy at inducing release via human vesicular monoamine transporters (hVMAT2). These compounds were low potency 1) h5-HT1A receptor partial agonists, 2) h5-HT2A receptor antagonists, 3) weak h5-HT2C receptor antagonists. This is the first report on aspects of substituted methcathinone efficacies at serotonin (5-HT) receptors and in superfusion release assays. Additionally, the drugs had no affinity for dopamine receptors, and high- mid-micromolar affinity for hSigma1 receptors. Thus, direct interactions with hVMAT2 and serotonin, dopamine, and hSigma1 receptors may not explain psychoactive effects. The primary mechanisms of action may be as inhibitors or substrates of DAT, SERT and NET. PMID:23583454

  16. 5-Hydroxytryptamine (serotonin)2A receptors in rat anterior cingulate cortex mediate the discriminative stimulus properties of d-lysergic acid diethylamide.

    PubMed

    Gresch, Paul J; Barrett, Robert J; Sanders-Bush, Elaine; Smith, Randy L

    2007-02-01

    d-Lysergic acid diethylamide (LSD), an indoleamine hallucinogen, produces profound alterations in mood, thought, and perception in humans. The brain site(s) that mediates the effects of LSD is currently unknown. In this study, we combine the drug discrimination paradigm with intracerebral microinjections to investigate the anatomical localization of the discriminative stimulus of LSD in rats. Based on our previous findings, we targeted the anterior cingulate cortex (ACC) to test its involvement in mediating the discriminative stimulus properties of LSD. Rats were trained to discriminate systemically administered LSD (0.085 mg/kg s.c.) from saline. Following acquisition of the discrimination, bilateral cannulae were implanted into the ACC (AP, +1.2 mm; ML, +/-1.0 mm; DV, -2.0 mm relative to bregma). Rats were tested for their ability to discriminate varying doses of locally infused LSD (0.1875, 0.375, and 0.75 microg/side) or artificial cerebrospinal fluid (n = 3-7). LSD locally infused into ACC dose-dependently substituted for systemically administered LSD, with 0.75 microg/side LSD substituting completely (89% correct). Systemic administration of the selective 5-hydroxytryptamine (serotonin) (5-HT)(2A) receptor antagonist R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine-methanol (M100907; 0.4 mg/kg) blocked the discriminative cue of LSD (0.375 microg/side) infused into ACC (from 68 to 16% drug lever responding). Furthermore, M100907 (0.5 microg/microl/side) locally infused into ACC completely blocked the stimulus effects of systemic LSD (0.04 mg/kg; from 80 to 12% on the LSD lever). Taken together, these data indicate that 5-HT(2A) receptors in the ACC are a primary target mediating the discriminative stimulus properties of LSD.

  17. Dopamine D2/3 receptor antagonism reduces activity-based anorexia

    PubMed Central

    Klenotich, S J; Ho, E V; McMurray, M S; Server, C H; Dulawa, S C

    2015-01-01

    Anorexia nervosa (AN) is an eating disorder characterized by severe hypophagia and weight loss, and an intense fear of weight gain. Activity-based anorexia (ABA) refers to the weight loss, hypophagia and paradoxical hyperactivity that develops in rodents exposed to running wheels and restricted food access, and provides a model for aspects of AN. The atypical antipsychotic olanzapine was recently shown to reduce both AN symptoms and ABA. We examined which component of the complex pharmacological profile of olanzapine reduces ABA. Mice received 5-HT2A/2C, 5-HT3, dopamine D1-like, D2, D3 or D2/3 antagonist treatment, and were assessed for food intake, body weight, wheel running and survival in ABA. D2/3 receptor antagonists eticlopride and amisulpride reduced weight loss and hypophagia, and increased survival during ABA. Furthermore, amisulpride produced larger reductions in weight loss and hypophagia than olanzapine. Treatment with either D3 receptor antagonist SB277011A or D2 receptor antagonist L-741,626 also increased survival. All the other treatments either had no effect or worsened ABA. Overall, selective antagonism of D2 and/or D3 receptors robustly reduces ABA. Studies investigating the mechanisms by which D2 and/or D3 receptors regulate ABA, and the efficacy for D2/3 and/or D3 antagonists to treat AN, are warranted. PMID:26241351

  18. Dopamine D2/3 receptor antagonism reduces activity-based anorexia.

    PubMed

    Klenotich, S J; Ho, E V; McMurray, M S; Server, C H; Dulawa, S C

    2015-08-04

    Anorexia nervosa (AN) is an eating disorder characterized by severe hypophagia and weight loss, and an intense fear of weight gain. Activity-based anorexia (ABA) refers to the weight loss, hypophagia and paradoxical hyperactivity that develops in rodents exposed to running wheels and restricted food access, and provides a model for aspects of AN. The atypical antipsychotic olanzapine was recently shown to reduce both AN symptoms and ABA. We examined which component of the complex pharmacological profile of olanzapine reduces ABA. Mice received 5-HT(2A/2C), 5-HT3, dopamine D1-like, D2, D3 or D2/3 antagonist treatment, and were assessed for food intake, body weight, wheel running and survival in ABA. D2/3 receptor antagonists eticlopride and amisulpride reduced weight loss and hypophagia, and increased survival during ABA. Furthermore, amisulpride produced larger reductions in weight loss and hypophagia than olanzapine. Treatment with either D3 receptor antagonist SB277011A or D2 receptor antagonist L-741,626 also increased survival. All the other treatments either had no effect or worsened ABA. Overall, selective antagonism of D2 and/or D3 receptors robustly reduces ABA. Studies investigating the mechanisms by which D2 and/or D3 receptors regulate ABA, and the efficacy for D2/3 and/or D3 antagonists to treat AN, are warranted.

  19. Pharmacological and pharmacokinetic properties of JNJ-40411813, a positive allosteric modulator of the mGlu2 receptor

    PubMed Central

    Lavreysen, Hilde; Ahnaou, Abdellah; Drinkenburg, Wilhelmus; Langlois, Xavier; Mackie, Claire; Pype, Stefan; Lütjens, Robert; Le Poul, Emmanuel; Trabanco, Andrés A; Nuñez, José María Cid

    2015-01-01

    Compounds modulating metabotropic glutamate type 2 (mGlu2) receptor activity may have therapeutic benefits in treating psychiatric disorders like schizophrenia and anxiety. The pharmacological and pharmacokinetic properties of a novel mGlu2 receptor-positive allosteric modulator (PAM), 1-butyl-3-chloro-4-(4-phenyl-1-piperidinyl)-2(1H)-pyridinone (JNJ-40411813/ADX71149) are described here. JNJ-40411813 acts as a PAM at the cloned mGlu2 receptor: EC50 = 147 ± 42 nmol/L in a [35S]GTPγS binding assay with human metabotropic glutamate type 2 (hmGlu2) CHO cells and EC50 = 64 ± 29 nmol/L in a Ca2+ mobilization assay with hmGlu2 Gα16 cotransfected HEK293 cells. [35S]GTPγS autoradiography on rat brain slices confirmed PAM activity of JNJ-40411813 on native mGlu2 receptor. JNJ-40411813 displaced [3H]JNJ-40068782 and [3H]JNJ-46281222 (mGlu2 receptor PAMs), while it failed to displace [3H]LY341495 (a competitive mGlu2/3 receptor antagonist). In rats, JNJ-40411813 showed ex vivo mGlu2 receptor occupancy using [3H]JNJ-46281222 with ED50 of 16 mg/kg (p.o.). PK-PD modeling using the same radioligand resulted in an EC50 of 1032 ng/mL. While JNJ-40411813 demonstrated moderate affinity for human 5HT2A receptor in vitro (Kb = 1.1 μmol/L), higher than expected 5HT2A occupancy was observed in vivo (in rats, ED50 = 17 mg/kg p.o.) due to a metabolite. JNJ-40411813 dose dependently suppressed REM sleep (LAD, 3 mg/kg p.o.), and promoted and consolidated deep sleep. In fed rats, JNJ-40411813 (10 mg/kg p.o.) was rapidly absorbed (Cmax 938 ng/mL at 0.5 h) with an absolute oral bioavailability of 31%. Collectively, our data show that JNJ-40411813 is an interesting candidate to explore the therapeutic potential of mGlu2 PAMs, in in vivo rodents experiments as well as in clinical studies. PMID:25692015

  20. Association between soluble lectin-like oxidized low-density lipoprotein receptor 1 levels and coronary slow flow phenomenon

    PubMed Central

    Caglar, Ilker Murat; Ozde, Cem; Caglar, Fatma Nihan Turhan; Akturk, Ibrahim Faruk; Ugurlucan, Murat; Karakaya, Osman

    2016-01-01

    Introduction The coronary slow flow phenomenon (CSFP) has been associated with myocardial ischemia, myocardial infarction, life-threatening arrhythmias, sudden cardiac death and increased cardiovascular mortality similar to coronary artery disease (CAD). Possible underlying mechanisms of CSFP are endothelial dysfunction, chronic inflammation, microvascular dysfunction and diffuse atherosclerosis. Soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) seems to play an important role in the pathogenesis of atherosclerosis. We hypothesized that sLOX-1 might be associated with CSFP, and aimed to research the relationship between sLOX-1 and CSFP. Material and methods Forty patients with angiographically proven CSFP and 43 patients with a normal coronary flow pattern (NCFP) were included in this study. Coronary blood flow was measured according to the Thrombolysis In Myocardial Infarction (TIMI) frame count method. sLOX-1 levels were measured in all study subjects. Results Serum levels of sLOX-1 were significantly higher in the CSFP group than the NCFP group (1061.80 ±422.20 ng/ml vs. 500.043 ±282.97 ng/ml, p < 0.001, respectively). Multivariate logistic regression analysis including sLOX-1, MPV, GGT and uric acid levels revealed a significant association between sLOX-1 levels and CSFP (Exp (B)/OR: 1.006, 95% CI: 1.002–1.010, p = 0.001). Conclusions The present study demonstrated that serum sLOX-1 levels were significantly higher in patients with CSFP and there was a strong association between high sLOX-1 levels and CSFP. High serum sLOX-1 levels may have an important role in the pathogenesis of CSFP. Future studies are needed to confirm these results. PMID:26925116

  1. Withania somnifera reverses Alzheimer's disease pathology by enhancing low-density lipoprotein receptor-related protein in liver

    PubMed Central

    Sehgal, Neha; Gupta, Alok; Valli, Rupanagudi Khader; Joshi, Shanker Datt; Mills, Jessica T.; Hamel, Edith; Khanna, Pankaj; Jain, Subhash Chand; Thakur, Suman S.; Ravindranath, Vijayalakshmi

    2012-01-01

    A 30-d course of oral administration of a semipurified extract of the root of Withania somnifera consisting predominantly of withanolides and withanosides reversed behavioral deficits, plaque pathology, accumulation of β-amyloid peptides (Aβ) and oligomers in the brains of middle-aged and old APP/PS1 Alzheimer's disease transgenic mice. It was similarly effective in reversing behavioral deficits and plaque load in APPSwInd mice (line J20). The temporal sequence involved an increase in plasma Aβ and a decrease in brain Aβ monomer after 7 d, indicating increased transport of Aβ from the brain to the periphery. Enhanced expression of low-density lipoprotein receptor-related protein (LRP) in brain microvessels and the Aβ-degrading protease neprilysin (NEP) occurred 14–21 d after a substantial decrease in brain Aβ levels. However, significant increase in liver LRP and NEP occurred much earlier, at 7 d, and were accompanied by a rise in plasma sLRP, a peripheral sink for brain Aβ. In WT mice, the extract induced liver, but not brain, LRP and NEP and decreased plasma and brain Aβ, indicating that increase in liver LRP and sLRP occurring independent of Aβ concentration could result in clearance of Aβ. Selective down-regulation of liver LRP, but not NEP, abrogated the therapeutic effects of the extract. The remarkable therapeutic effect of W. somnifera mediated through up-regulation of liver LRP indicates that targeting the periphery offers a unique mechanism for Aβ clearance and reverses the behavioral deficits and pathology seen in Alzheimer's disease models. PMID:22308347

  2. Biodistribution of AAV8 Vectors Expressing Human Low-Density Lipoprotein Receptor in a Mouse Model of Homozygous Familial Hypercholesterolemia

    PubMed Central

    Chen, Shu-Jen; Sanmiguel, Julio; Lock, Martin; McMenamin, Deirdre; Draper, Christine; Limberis, Maria P.; Kassim, Sadik H.; Somanathan, Suryanarayan; Bell, Peter; Johnston, Julie C.; Rader, Daniel J.

    2013-01-01

    Abstract Recombinant adeno-associated viral vectors based on serotype 8 (AAV8) transduce liver with superior tropism following intravenous (IV) administration. Previous studies conducted by our lab demonstrated that AAV8-mediated transfer of the human low-density lipoprotein receptor (LDLR) gene driven by a strong liver-specific promoter (thyroxin-binding globulin [TBG]) leads to high level and persistent gene expression in the liver. The approach proved efficacious in reducing plasma cholesterol levels and resulted in the regression of atherosclerotic lesions in a murine model of homozygous familial hypercholesterolemia (hoFH). Prior to advancing this vector, called AAV8.TBG.hLDLR, to the clinic, we set out to investigate vector biodistribution in an hoFH mouse model following IV vector administration to assess the safety profile of this investigational agent. Although AAV genomes were present in all organs at all time points tested (up to 180 days), vector genomes were sequestered mainly in the liver, which contained levels of vector 3 logs higher than that found in other organs. In both sexes, the level of AAV genomes gradually declined and appeared to stabilize 90 days post vector administration in most organs although vector genomes remained high in liver. Vector loads in the circulating blood were high and close to those in liver at the early time point (day 3) but rapidly decreased to a level close to the limit of quantification of the assay. The results of this vector biodistribution study further support a proposed clinical trial to evaluate AAV8 gene therapy for hoFH patients. PMID:24070336

  3. Biodistribution of AAV8 vectors expressing human low-density lipoprotein receptor in a mouse model of homozygous familial hypercholesterolemia.

    PubMed

    Chen, Shu-Jen; Sanmiguel, Julio; Lock, Martin; McMenamin, Deirdre; Draper, Christine; Limberis, Maria P; Kassim, Sadik H; Somanathan, Suryanarayan; Bell, Peter; Johnston, Julie C; Rader, Daniel J; Wilson, James M

    2013-12-01

    Recombinant adeno-associated viral vectors based on serotype 8 (AAV8) transduce liver with superior tropism following intravenous (IV) administration. Previous studies conducted by our lab demonstrated that AAV8-mediated transfer of the human low-density lipoprotein receptor (LDLR) gene driven by a strong liver-specific promoter (thyroxin-binding globulin [TBG]) leads to high level and persistent gene expression in the liver. The approach proved efficacious in reducing plasma cholesterol levels and resulted in the regression of atherosclerotic lesions in a murine model of homozygous familial hypercholesterolemia (hoFH). Prior to advancing this vector, called AAV8.TBG.hLDLR, to the clinic, we set out to investigate vector biodistribution in an hoFH mouse model following IV vector administration to assess the safety profile of this investigational agent. Although AAV genomes were present in all organs at all time points tested (up to 180 days), vector genomes were sequestered mainly in the liver, which contained levels of vector 3 logs higher than that found in other organs. In both sexes, the level of AAV genomes gradually declined and appeared to stabilize 90 days post vector administration in most organs although vector genomes remained high in liver. Vector loads in the circulating blood were high and close to those in liver at the early time point (day 3) but rapidly decreased to a level close to the limit of quantification of the assay. The results of this vector biodistribution study further support a proposed clinical trial to evaluate AAV8 gene therapy for hoFH patients. PMID:24070336

  4. Minimally modified low-density lipoprotein induces macrophage endoplasmic reticulum stress via toll-like receptor 4.

    PubMed

    Yao, Shutong; Yang, Nana; Song, Guohua; Sang, Hui; Tian, Hua; Miao, Cheng; Zhang, Ying; Qin, Shucun

    2012-07-01

    Minimally modified low-density lipoprotein (mm-LDL) induces intimal foam cell formation, which is promoted by endoplasmic reticulum stress (ERS), a cross-point to link cellular processes with multiple risk factors that exist in all stages of atherosclerosis. However, it remains unclear whether mm-LDL-induced lipid accumulation in macrophages involves ERS and its underlying mechanisms. We showed that mm-LDL induced the accumulation of lipid droplets in RAW264.7 macrophages with increased free cholesterol in the endoplasmic reticulum, which was markedly attenuated by pretreatment with an antibody against toll-like receptor 4 (TLR4). Additionally, mm-LDL stimulated the transport of Cy3-labeled activating transcription factor 6 (ATF6), a key sensor to the unfolded protein response (UPR), from cytoplasm into nucleus. The expression of phosphorylated inositol-requiring enzyme 1 (p-IRE1), another sensor to the UPR, and its two downstream molecules, X box binding protein 1 and glucose-regulated protein 78 (GRP78), were significantly upregulated by mm-LDL. The alterations induced by mm-LDL were all significantly inhibited by antibodies against TLR4 or CD36. In addition, the upregulation of p-IRE1 and GRP78 and the nuclear translocation of ATF6 induced by mm-LDL were significantly attenuated by TLR4 siRNA. These results suggest that mm-LDL may induce free cholesterol accumulation in the endoplasmic reticulum and subsequently stimulate ERS and activate the UPR signaling pathway mediated by ATF6 and IRE1 in macrophages, a process that is potentially mediated by TLR4. PMID:22480542

  5. Development of Accelerated Coronary Atherosclerosis Model Using Low Density Lipoprotein Receptor Knock-Out Swine with Balloon Injury

    PubMed Central

    Ogita, Manabu; Miyauchi, Katsumi; Onishi, Akira; Tsuboi, Shuta; Wada, Hideki; Konishi, Hirokazu; Naito, Ryo; Dohi, Tomotaka; Kasai, Takatoshi; Kojima, Yuko; Schwartz, Robert S.; Daida, Hiroyuki

    2016-01-01

    Background Several animal models have facilitated the evaluation and pathological understanding of atherosclerosis, but a definitive animal model of coronary atherosclerosis is not available. We therefore developed low density lipoprotein receptor knockout (LDLR-KO) pigs with hypercholesterolemia, a model which rapidly developed coronary atherosclerosis following balloon injury. Methods and Results We deleted LDLR exon regions from cultured porcine fetal fibroblasts and cloned LDLR knockout (LDLR-KO) embryos microinjecting fetal fibroblast nuclei into enucleated oocytes. Twelve LDLR-KO pigs were fed a 2.0% cholesterol and 20% fat diet. Baseline serum LDL cholesterol level was 510.0±86.1 mg/dL. Balloon injury was created in 46 coronary segments and necropsy were obtained 2, 4, 8 and 12 weeks later. Coronary artery sections were reviewed to evaluate lesion progression. We found lipid accumulation with foam cells and inflammatory cells beginning four weeks after balloon injury. The mean ratio of macrophages to plaque area was significantly higher in the four- weeks and eight-week animals compared with those at 2-weeks (8.79% ± 5.98% and 17.00% ± 10.38% vs. 1.14% ± 1.88%, P < 0.0001). At 12 weeks the ratio decreased toward the level at 2 week level (4.00% ± 4.56%, P = 0.66 vs. baseline). Advanced coronary atherosclerotic lesions contained lipid pools at eight-weeks with fibrous components beginning at 12 weeks. Conclusions We developed a model of rapid coronary atherosclerosis using LDLR KO pigs with balloon injury. This model may be useful for preclinical evaluation of medication or devices, and may also help investigate mechanisms of plaque progression. PMID:27631974

  6. Recombinant hepatitis C virus-envelope protein 2 interactions with low-density lipoprotein/CD81 receptors

    PubMed Central

    Urbaczek, Ana Carolina; Ximenes, Valdecir Farias; Afonso, Ana; Generoso, Wesley Cardoso; Nogueira, Camila Tita; Tansini, Aline; Cappelini, Luciana Teresa Dias; Malagó, Wilson; da Silva, Flávio Henrique; da Fonseca, Luiz Marcos; da Costa, Paulo Inácio

    2015-01-01

    Hepatitis C virus (HCV) envelope protein 2 (E2) is involved in viral binding to host cells. The aim of this work was to produce recombinant E2B and E2Y HCV proteins in Escherichia coli and Pichia pastoris, respectively, and to study their interactions with low-density lipoprotein receptor (LDLr) and CD81 in human umbilical vein endothelial cells (HUVEC) and the ECV304 bladder carcinoma cell line. To investigate the effects of human LDL and differences in protein structure (glycosylated or not) on binding efficiency, the recombinant proteins were either associated or not associated with lipoproteins before being assayed. The immunoreactivity of the recombinant proteins was analysed using pooled serum samples that were either positive or negative for hepatitis C. The cells were immunophenotyped by LDLr and CD81 using flow cytometry. Binding and binding inhibition assays were performed in the presence of LDL, foetal bovine serum (FCS) and specific antibodies. The results revealed that binding was reduced in the absence of FCS, but that the addition of human LDL rescued and increased binding capacity. In HUVEC cells, the use of antibodies to block LDLr led to a significant reduction in the binding of E2B and E2Y. CD81 antibodies did not affect E2B and E2Y binding. In ECV304 cells, blocking LDLr and CD81 produced similar effects, but they were not as marked as those that were observed in HUVEC cells. In conclusion, recombinant HCV E2 is dependent on LDL for its ability to bind to LDLr in HUVEC and ECV304 cells. These findings are relevant because E2 acts to anchor HCV to host cells; therefore, high blood levels of LDL could enhance viral infectivity in chronic hepatitis C patients. PMID:26018451

  7. Bone Mineral Density Changes Among Women Initiating Proton Pump Inhibitors or H2 Receptor Antagonists: A SWAN Cohort Study

    PubMed Central

    Solomon, Daniel H; Diem, Susan J; Ruppert, Kristine; Juan Lian, Yin; Liu, Chih-Chin; Wohlfart, Alyssa; Greendale, Gail A; Finkelstein, Joel S

    2015-01-01

    Proton pump inhibitors (PPIs) have been associated with diminished bone mineral density (BMD) and an increased risk of fracture; however, prior studies have not yielded consistent results, and many have suboptimal ascertainment of both PPI use and BMD. We used data from the Study of Women’s Health Across the Nation (SWAN), a multicenter, multi-ethnic, community-based longitudinal cohort study of women across the menopause transition to examine the association between annualized BMD changes and new use of PPIs. We compared changes in BMD in new PPI users with changes in BMD in new users of histamine 2 receptor antagonists (H2RAs) and with changes in BMD in subjects who did not use either class of medications. Mixed linear regression models included recognized risk factors for osteoporosis, including demographics, menopausal transition stage, body mass index (BMI), lifestyle factors, as well as comorbidities and concomitant medications. To provide further evidence for the validity of our analytic approach, we also examined the effects of hormone-replacement therapy (HT), a class of medications that should reduce bone loss, on changes in BMD as an internal positive control group. We identified 207 new users of PPIs, 185 new users of H2RAs, and 1,676 non-users. Study subjects had a mean age of 50 years and were followed for a median of 9.9 years. Adjusted models found no difference in the annualized BMD change at the lumbar spine, femoral neck, or total hip in PPI users compared with H2RA users or non-users. These results were robust to sensitivity analyses. BMD increased as expected in HT users, supporting the validity of our study design. These longitudinal analyses plus similar prior studies argue against an association between PPI use and BMD loss. PMID:25156141

  8. Lipoprotein(a) Catabolism Is Regulated by Proprotein Convertase Subtilisin/Kexin Type 9 through the Low Density Lipoprotein Receptor*

    PubMed Central

    Romagnuolo, Rocco; Scipione, Corey A.; Boffa, Michael B.; Marcovina, Santica M.; Seidah, Nabil G.; Koschinsky, Marlys L.

    2015-01-01

    Elevated levels of lipoprotein(a) (Lp(a)) have been identified as an independent risk factor for coronary heart disease. Plasma Lp(a) levels are reduced by monoclonal antibodies targeting proprotein convertase subtilisin/kexin type 9 (PCSK9). However, the mechanism of Lp(a) catabolism in vivo and the role of PCSK9 in this process are unknown. We report that Lp(a) internalization by hepatic HepG2 cells and primary human fibroblasts was effectively reduced by PCSK9. Overexpression of the low density lipoprotein (LDL) receptor (LDLR) in HepG2 cells dramatically increased the internalization of Lp(a). Internalization of Lp(a) was markedly reduced following treatment of HepG2 cells with a function-blocking monoclonal antibody against the LDLR or the use of primary human fibroblasts from an individual with familial hypercholesterolemia; in both cases, Lp(a) internalization was not affected by PCSK9. Optimal Lp(a) internalization in both hepatic and primary human fibroblasts was dependent on the LDL rather than the apolipoprotein(a) component of Lp(a). Lp(a) internalization was also dependent on clathrin-coated pits, and Lp(a) was targeted for lysosomal and not proteasomal degradation. Our data provide strong evidence that the LDLR plays a role in Lp(a) catabolism and that this process can be modulated by PCSK9. These results provide a direct mechanism underlying the therapeutic potential of PCSK9 in effectively lowering Lp(a) levels. PMID:25778403

  9. Bone mineral density changes among women initiating proton pump inhibitors or H2 receptor antagonists: a SWAN cohort study.

    PubMed

    Solomon, Daniel H; Diem, Susan J; Ruppert, Kristine; Lian, Yin Juan; Liu, Chih-Chin; Wohlfart, Alyssa; Greendale, Gail A; Finkelstein, Joel S

    2015-02-01

    Proton pump inhibitors (PPIs) have been associated with diminished bone mineral density (BMD) and an increased risk of fracture; however, prior studies have not yielded consistent results, and many have suboptimal ascertainment of both PPI use and BMD. We used data from the Study of Women's Health Across the Nation (SWAN), a multicenter, multi-ethnic, community-based longitudinal cohort study of women across the menopause transition to examine the association between annualized BMD changes and new use of PPIs. We compared changes in BMD in new PPI users with changes in BMD in new users of histamine 2 receptor antagonists (H2RAs) and with changes in BMD in subjects who did not use either class of medications. Mixed linear regression models included recognized risk factors for osteoporosis, including demographics, menopausal transition stage, body mass index (BMI), lifestyle factors, as well as comorbidities and concomitant medications. To provide further evidence for the validity of our analytic approach, we also examined the effects of hormone-replacement therapy (HT), a class of medications that should reduce bone loss, on changes in BMD as an internal positive control group. We identified 207 new users of PPIs, 185 new users of H2RAs, and 1,676 non-users. Study subjects had a mean age of 50 years and were followed for a median of 9.9 years. Adjusted models found no difference in the annualized BMD change at the lumbar spine, femoral neck, or total hip in PPI users compared with H2RA users or non-users. These results were robust to sensitivity analyses. BMD increased as expected in HT users, supporting the validity of our study design. These longitudinal analyses plus similar prior studies argue against an association between PPI use and BMD loss. PMID:25156141

  10. Differential effects of three 5-HT receptor antagonists on the performance of rats in attentional and working memory tasks.

    PubMed

    Ruotsalainen, S; Sirviö, J; Jäkälä, P; Puumala, T; MacDonald, E; Riekkinen, P

    1997-05-01

    The effects of three different serotonin (5-HT) receptor antagonists (ketanserin, methysegide, methiothepin) in the modulation of attention, working memory and behavioural activity were investigated in this study by assessing the performance of rats in two separate cognitive models; the 5-choice serial reaction time (5-CSRT) task, which measures attention, and the delayed non-matching to position (DNMTP) task, which measures working memory. Methysergide and methiothepin bind at the 5-HT1 and 5-HT2 as well as the 5-HT5-7 receptors, with varying degrees of selectivity, and ketanserin binds at the 5-HT2A receptors rather selectively. None of these agents bind to any significant extent to 5-HT3 or 5-HT4 receptors. In the 5-CSRT task, neither methiothepin (0.15 mg/kg) nor ketanserin (1.0 and 3.0 mg/kg) impaired the choice accuracy of rats, although they induced sedation. The low doses of methysergide (1.5 and 3.0 mg/kg) slightly increased the behavioural activity of rats, whereas the high dose of methysergide (15.0 mg/kg) reduced behavioural activity and slightly reduced choice accuracy of the rats in the attentional task (monitoring of visual stimuli) under the baseline conditions or curtailed stimulus duration. This effect was not augmented at the reduced stimulus intensity. These findings suggest that the high dose of methysergide did not interfere with the visual discrimination of rats. Furthermore, methysergide did not reduce motivation for this task, since it did not increase food collection latencies. In the DNMTP task, methiothepin (0.15 mg/kg) induced a delay non-dependent deficit in choice accuracy. This could be due to an impaired alternation ability or akinesia, which increases an actual delay between sample and choice. Methiothepin (0.15 mg/kg) also interfered with behavioural activity of rats. Interestingly, ketanserin (1.0 mg/kg and 3.0 mg/kg) and methysergide (3.0-15.0 mg/kg) neither impaired the choice accuracy nor reduced the behavioural activity of

  11. Spinal 5-HT-receptors and tonic modulation of transmission through a withdrawal reflex pathway in the decerebrated rabbit.

    PubMed Central

    Clarke, R. W.; Harris, J.; Houghton, A. K.

    1996-01-01

    1. In decerebrated, non-spinalized rabbits, intrathecal administration of either of the selective 5-HT1A-receptor antagonists (S)WAY-100135 or WAY-100635 resulted in dose-dependent enhancement of the reflex responses of gastrocnemius motoneurones evoked by electrical stimulation of all myelinated afferents of the sural nerve. The approximate ED50 for WAY-100635 was 0.9 nmol and that for (S)WAY-100135 13 nmol. Intrathecal doses of the antagonists which caused maximal facilitation of reflexes in non-spinalized rabbits had no effect in spinalized preparations. 2. In non-spinalized animals, intravenous administration of (S)WAY-100135 was significantly less effective in enhancing reflexes than when it was given by the intrathecal route. 3. When given intrathecally, the selective 5-HT 2A/2C-receptor antagonist, ICI 170,809, produced a bellshaped dose-effect curve, augmenting reflexes at low doses (< or = 44 nmol), but reducing them at higher doses (982 nmol). Idazoxan, the selective alpha 2-adrenoceptor antagonist, was less effective in enhancing reflex responses when given intrathecally after ICI 170,809 compared to when it was given alone. Intravenous ICI 170,809 resulted only in enhancement of reflexes and the facilitatory effects of subsequent intrathecal administration of idazoxan were not compromised. 4. The selective 5-HT3-receptor blocker ondansetron faciliated gastrocnemius medialis reflex responses in a dose-related manner when given by either intrathecal or intravenous routes. This drug was slightly more potent when given i.v. and it did not alter the efficacy of subsequent intrathecal administration of idazoxan. 5. None of the antagonists had any consistent effects on arterial blood pressure or heart rate. 6. These data are consistent with the idea that, in the decrebrated rabbit, 5-HT released from descending axons has multiple roles in controlling transmission through the sural-gastrocnemius medialis reflex pathway. Thus, it appears 5-HT tonically inhibits

  12. Six DNA polymorphisms in the low density lipoprotein receptor gene: their genetic relationship and an example of their use for identifying affected relatives of patients with familial hypercholesterolaemia.

    PubMed Central

    Humphries, S; King-Underwood, L; Gudnason, V; Seed, M; Delattre, S; Clavey, V; Fruchart, J C

    1993-01-01

    We have determined the relative allele frequency and estimated linkage disequilibrium between six DNA polymorphisms of the low density lipoprotein (LDL) receptor gene. Polymorphisms were detected using the enzymes SfaNI, TaqI, StuI, HincII, AvaII, and NcoI after DNA amplification by the polymerase chain reaction. Strong linkage disequilibrium was detected between many of the pair wise comparisons in a sample of 60 patients heterozygous for familial hypercholesterolaemia (FH). Using the enzymes HincII, NcoI, and SfaNI, 85% of patients were heterozygous for at least one polymorphism and thus potentially informative for cosegregation studies. The polymorphisms were used to follow the inheritance of the defective allele of the LDL receptor gene in the relatives of a patient with FH. Assays of LDL receptor activity on lymphoblastoid cell lines from two members of the family was used to confirm that the proband, but not the hypercholesterolaemic brother, had a defect in the LDL receptor. In the family, none of the children had inherited the allele of the LDL receptor gene inferred to be defective. The problems associated with this cosegregation approach to identify relatives of patients with a clinical diagnosis of FH are discussed. PMID:8098067

  13. The use of low density lipoprotein receptor activity of lymphocytes to determine the prevalence of familial hypercholesterolaemia in a rural South African community.

    PubMed Central

    Steyn, K; Weight, M J; Dando, B R; Christopher, K J; Rossouw, J E

    1989-01-01

    The diagnosis of heterozygous familial hypercholesterolaemia in three rural South African communities in which hypercholesterolaemia is very prevalent could be confirmed by the measurement of low density lipoprotein (LDL) receptor activity in circulating lymphocytes. A nominal cut off point could be proposed which separated the LDL receptor activity of 24 clinically diagnosed heterozygous FH patients and 31 healthy people. LDL receptor activity was measured as total degradation of 125I-LDL and expressed as ng LDL/mg cell protein/6 hours. The cut off point was set at 970 ng/mg protein/6 hours. This proposed cut off point was tested by assaying the LDL receptor of three homozygous FH patients and seven of their obligate heterozygous FH first degree relatives. The three homozygous FH patients showed no receptor activity and the activity of the seven obligate heterozygous first degree relatives fell below the proposed cut off point. To determine the prevalence of FH in the study population, all persons aged 15 to 24 years whose total cholesterol levels fell above the 80th centile for their age and sex, as well as their families, were approached (n = 114). The LDL receptor activity in lymphocytes of 77 of these persons aged 15 to 24 years was determined after applying the exclusion criteria. Ten of the 77 participants had LDL receptor activity below 970 ng LDL/mg protein/6 hours and were therefore diagnosed as being heterozygous FH patients. The calculation of the prevalence (corrected for exclusions) revealed that one in 71 of the 15 to 24 year old permanent residents in the predominantly Afrikaans speaking community suffered from heterozygous FH. This is higher than any FH prevalence previously reported for any group. PMID:2918524

  14. Post-synaptic Density-95 (PSD-95) Binding Capacity of G-protein-coupled Receptor 30 (GPR30), an Estrogen Receptor That Can Be Identified in Hippocampal Dendritic Spines*

    PubMed Central

    Akama, Keith T.; Thompson, Louisa I.; Milner, Teresa A.; McEwen, Bruce S.

    2013-01-01

    The estrogen 17β-estradiol (E2) modulates dendritic spine plasticity in the cornu ammonis 1 (CA1) region of the hippocampus, and GPR30 (G-protein coupled estrogen receptor 1 (GPER1)) is an estrogen-sensitive G-protein-coupled receptor (GPCR) that is expressed in the mammalian brain and in specific subregions that are responsive to E2, including the hippocampus. The subcellular localization of hippocampal GPR30, however, remains unclear. Here, we demonstrate that GPR30 immunoreactivity is detected in dendritic spines of rat CA1 hippocampal neurons in vivo and that GPR30 protein can be found in rat brain synaptosomes. GPR30 immunoreactivity is identified at the post-synaptic density (PSD) and in the adjacent peri-synaptic zone, and GPR30 can associate with the spine scaffolding protein PSD-95 both in vitro and in vivo. This PSD-95 binding capacity of GPR30 is specific and determined by the receptor C-terminal tail that is both necessary and sufficient for PSD-95 interaction. The interaction with PSD-95 functions to increase GPR30 protein levels residing at the plasma membrane surface. GPR30 associates with the N-terminal tandem pair of PDZ domains in PSD-95, suggesting that PSD-95 may be involved