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Sample records for 5-ht transporter binding

  1. Platelet 5-hydroxytryptamine (5-HT) transporter and 5-HT2A receptor binding after chronic hypercorticosteronemia, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane administration or neurotoxin-induced depletion of central nervous system 5-HT in the rat.

    PubMed

    Owens, M J; Ballenger, C A; Knight, D L; Nemeroff, C B

    1996-09-01

    There is considerable evidence that the number of platelet 5-hydroxytryptamine (5-HT) transporter binding sites, as measured by [3H]imipramine binding, are significantly decreased, and platelet 5-HT2 receptor density is increased, in drug-free patients with major depression. To investigate whether these changes in the platelet 5-HT transporter or 5-HT2 receptor sites resulted from known or hypothesized biochemical changes observed in major depression, we examined, in the rat, whether a chronic hyperglucocorticoid state, or decreases or increases in central nervous system 5-HT neurotransmission, altered binding of the selective ligands [3H]citalopram and [125I] (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane to platelet and brain 5-HT transporters and 5-HT2 receptors, respectively. Chronic (6 weeks) hypercorticosteronemia did not alter either brain or platelet 5-HT transporter or 5-HT2A receptor binding. Similarly, 8-week administration of the 5-HT2A/5-HT2C agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, at a dose which down-regulates brain 5-HT2A/2C receptors, did not alter brain or platelet 5-HT transporters or platelet 5-HT2A receptors. Additionally, para-chloroamphetamine-(11 weeks) or fenfluramine-induced chronic (1.5-10 weeks) depletion of central nervous system 5-HT did not alter platelet 5-HT transporter or 5-HT2A receptor binding. Finally, there was no correlation between the number of 5-HT transporters in brain and platelets in any of the control or treatment groups. These findings suggest that the observed changes in platelet 5-HT transporter and 5-HT2A receptor binding in depressed patients are more apt to be of genetic origin (i.e., trait-dependent) rather than an epiphenomenon of hypercortisolemia or altered central nervous system 5-HT status.

  2. Effects of olanzapine and betahistine co-treatment on serotonin transporter, 5-HT2A and dopamine D2 receptor binding density.

    PubMed

    Lian, Jiamei; Huang, Xu-Feng; Pai, Nagesh; Deng, Chao

    2013-12-02

    Olanzapine is widely used in treating multiple domains of schizophrenia symptoms but induces serious metabolic side-effects. Recent evidence has showed that co-treatment of betahistine (a histaminergic H1 receptor agonist and H3 receptor antagonist) is effective for preventing olanzapine-induced weight gain/obesity, however it is not clear whether this co-treatment affects on the primary therapeutic receptor binding sites of olanzapine such as serotonergic 5-HT2A receptors (5-HT2AR) and dopaminergic D2 receptors (D2R). Therefore, this study investigated the effects of this co-treatment on 5-HT2AR, 5-HT transporter (5-HTT) and D2R bindings in various brain regions involved in antipsychotic efficacy. Female Sprague Dawley rats were administered orally (t.i.d.) with either olanzapine (1mg/kg), betahistine (2.7 mg/kg), olanzapine plus betahistine (O+B), or vehicle (control) for 2 weeks. Quantitative autoradiography was used to detect the density of [(3)H]ketanserin, [(3)H]paroxetine and [(3)H]raclopride binding site to 5-HT2AR, 5-HTT and D2R. Compared to the controls, olanzapine significantly decreased [(3)H]ketanserin bindings to 5-HT2AR in the prefrontal cortex, cingulate cortex, and nucleus accumbens. Similar changes in 5-HT2AR bindings in these nuclei were also observed in the O+B co-treatment group. Olanzapine also significantly decreased [(3)H]paroxetine binding to 5-HTT in the ventral tegmental area and substantia nigra, however, both olanzapine only and O+B co-treatment did not affect [(3)H]raclopride binding to D2R. The results confirmed the important role of 5-HT2AR in the efficacy of olanzapine, which is not influenced by the O+B co-treatment. Therefore, betahistine co-treatment would be an effective combination therapy to reduce olanzapine-induced weight gain side-effects without affecting olanzapine's actions on 5-HT2AR transmissions.

  3. Studies of the biogenic amine transporters. V. Demonstration of two binding sites for the cocaine analog [125I]RTI-55 associated with the 5-HT transporter in rat brain membranes.

    PubMed

    Silverthorn, M L; Dersch, C M; Baumann, M H; Cadet, J L; Partilla, J S; Rice, K C; Carroll, F I; Becketts, K M; Brockington, A; Rothman, R B

    1995-04-01

    Earlier work characterized the binding of the high-affinity cocaine analog 3 beta-(4-125iodophenyl)-tropane-2-carboxylic acid methyl ester ([125I]RTI-55) to membranes prepared from rat caudate. That investigation demonstrated that [125I]RTI-55-labeled serotonin (5-HT) transporters in addition to dopamine (DA) transporters and resolved [125I]RTI-55 binding to 5-HT transporters into two distinct components. In the present study, we characterized [125I]RTI-55 binding to membranes prepared from whole rat brain minus caudate. The first series of experiments established that [125I]RTI-55 labels both DA and 5-HT transporters and that 50 nM paroxetine and either 1000 nM 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)homopiperazine (LR1111) or 500 nM (RTI-120) could be used to block [125I]RTI-55 binding to the 5-HT and DA transporters, thereby generating selective assay conditions for the DA and 5-HT transporters, respectively. Selective lesioning of dopaminergic and serotonergic neurons with intracerebroventricular 6-hydroxydopamine and 5,7-dihydroxytryptamine selectively decreased [125I]RTI-55 binding to DA and 5-HT transporters, respectively, thereby confirming the selectivity of the assay conditions. The ligand-selectivity pattern of the whole brain minus caudate 5-HT transporter correlated significantly with that of the caudate 5-HT transporter, although there were some striking differences for selected test agents. Additional experiments resolved [125I]RTI-55 binding to the 5-HT transporter into two components. A ligand-selectivity analysis of the two components failed to identify a highly selective test agent. In summary, the major findings of the present study are that [125I]RTI-55 labels both DA and 5-HT transporters in membranes prepared from whole brain minus caudate, that 50 nM paroxetine and either 1000 nM LR1111 or 500 nM RTI-120 can be used as a blocking agent to generate selective assay conditions for the DA and 5-HT transporters, respectively, and that [125

  4. Methylene blue inhibits function of the 5-HT transporter

    PubMed Central

    Oz, Murat; Isaev, Dmytro; Lorke, Dietrich E; Hasan, Muhammed; Petroianu, Georg; Shippenberg, Toni S

    2012-01-01

    BACKGROUND AND PURPOSE Methylene blue (MB) is commonly employed as a treatment for methaemoglobinaemia, malaria and vasoplegic shock. An increasing number of studies indicate that MB can cause 5-HT toxicity when administered with a 5-HT reuptake inhibitor. MB is a potent inhibitor of monoamine oxidases, but other targets that may contribute to MB toxicity have not been identified. Given the role of the 5-HT transporter (SERT) in the regulation of extracellular 5-HT concentrations, the present study aimed to characterize the effect of MB on SERT. EXPERIMENTAL APPROACH Live cell imaging, in conjunction with the fluorescent SERT substrate 4-(4-(dimethylamino)-styryl)-N-methylpyridinium (ASP+), [3H]5-HT uptake and whole-cell patch-clamp techniques were employed to examine the effects of MB on SERT function. KEY RESULTS In EM4 cells expressing GFP-tagged human SERT (hSERT), MB concentration-dependently inhibited ASP+ accumulation (IC50: 1.4 ± 0.3 µM). A similar effect was observed in N2A cells. Uptake of [3H]5-HT was decreased by MB pretreatment. Furthermore, patch-clamp studies in hSERT expressing cells indicated that MB significantly inhibited 5-HT-evoked ion currents. Pretreatment with 8-Br-cGMP did not alter the inhibitory effect of MB on hSERT activity, and intracellular Ca2+ levels remained unchanged during MB application. Further experiments revealed that ASP+ binding to cell surface hSERT was reduced after MB treatment. In whole-cell radioligand experiments, exposure to MB (10 µM; 10 min) did not alter surface binding of the SERT ligand [125I]RTI-55. CONCLUSIONS AND IMPLICATIONS MB modulated SERT function and suggested that SERT may be an additional target upon which MB acts to produce 5-HT toxicity. PMID:21542830

  5. Comparative receptor mapping of serotoninergic 5-HT3 and 5-HT4 binding sites*

    NASA Astrophysics Data System (ADS)

    López-Rodríguez, María L.; Morcillo, María José; Benhamú, Bellinda; Rosado, María Luisa

    1997-11-01

    The clinical use of currently available drugs acting at the5-HT4 receptor has been hampered by their lack of selectivityover 5-HT3 binding sites. For this reason, there is considerableinterest in the medicinal chemistry of these serotonin receptor subtypes, andsignificant effort has been made towards the discovery of potent and selectiveligands. Computer-aided conformational analysis was used to characterizeserotoninergic 5-HT3 and 5-HT4 receptorrecognition. On the basis of the generally accepted model of the5-HT3 antagonist pharmacophore, we have performed a receptormapping of this receptor binding site, following the active analog approach(AAA) defined by Marshall. The receptor excluded volume was calculated as theunion of the van der Waals density maps of nine active ligands(pKi ≥ 8.9), superimposed in pharmacophoric conformations.Six inactive analogs (pKi < 7.0) were subsequently used todefine the essential volume, which in its turn can be used to define theregions of steric intolerance of the 5-HT3 receptor. Five activeligands (pKi ≥ 9.3) at 5-HT4 receptors wereused to construct an antagonist pharmacophore for this receptor, and todetermine its excluded volume by superimposition of pharmacophoricconformations. The volume defined by the superimposition of five inactive5-HT4 receptor analogs that possess the pharmacophoric elements(pKi ≤ 6.6) did not exceed the excluded volume calculated forthis receptor. In this case, the inactivity may be due to the lack of positiveinteraction of the amino moiety with a hypothetical hydrophobic pocket, whichwould interact with the voluminous substituents of the basic nitrogen ofactive ligands. The difference between the excluded volumes of both receptorshas confirmed that the main difference is indeed in the basic moiety. Thus,the 5-HT3 receptor can only accommodate small substituents inthe position of the nitrogen atom, whereas the 5-HT4 receptorrequires more voluminous groups. Also, the basic nitrogen is located at ca

  6. High trait aggression in men is associated with low 5-HT levels, as indexed by 5-HT4 receptor binding.

    PubMed

    da Cunha-Bang, Sofi; Mc Mahon, Brenda; Fisher, Patrick MacDonald; Jensen, Peter Steen; Svarer, Claus; Knudsen, Gitte Moos

    2016-04-01

    Impulsive aggression has commonly been associated with a dysfunction of the serotonin (5-HT) system: many, but not all, studies point to an inverse relationship between 5-HT and aggression. As cerebral 5-HT4 receptor (5-HT4R) binding has recently been recognized as a proxy for stable brain levels of 5-HT, we here test the hypothesis in healthy men and women that brain 5-HT levels, as indexed by cerebral 5-HT4R, are inversely correlated with trait aggression and impulsivity. Sixty-one individuals (47 men) underwent positron emission tomography scanning with the radioligand [(11)C]SB207145 for quantification of brain 5-HT4R binding. The Buss-Perry Aggression Questionnaire (BPAQ) and the Barratt Impulsiveness Scale were used for assessment of trait aggression and trait impulsivity. Among male subjects, there was a positive correlation between global 5-HT4R and BPAQ total score (P = 0.037) as well as BPAQ physical aggression (P = 0.025). No main effect of global 5-HT4R on trait aggression or impulsivity was found in the mixed gender sample, but there was evidence for sex interaction effects in the relationship between global 5-HT4R and BPAQ physical aggression. In conclusion we found that low cerebral 5-HT levels, as indexed by 5-HT4R binding were associated with high trait aggression in males, but not in females.

  7. Contractile 5-HT1 receptors in human isolated pial arterioles: correlation with 5-HT1D binding sites.

    PubMed Central

    Hamel, E.; Bouchard, D.

    1991-01-01

    1. The 5-hydroxytryptamine (5-HT) receptor responsible for inducing vasoconstriction in human isolated pial arterioles has been pharmacologically characterized. 2. Of several 5-HT agonists tested, 5-carboxamidotryptamine (5-CT) was the most potent and the rank order of agonist potency can be summarized as: 5-CT greater than 5-HT greater than RU 24969 = alpha-methyl-5-HT = methysergide much greater than MDL 72832 = 2-methyl-5-HT much greater than 2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydro-naphthalene (8-OH-DPAT). With few exceptions, the maximal contractile responses of these agonists were comparable to that induced by 5-HT. 3. A correlation analysis performed between the agonists vascular potency (pD2 values) and their affinities (pKD values) published at various subtypes of 5-HT binding sites showed a positive significant correlation with rat cortical 5-HT1B (r = 0.86; P less than 0.01) and human caudate 5-HT1D (r = 0.98; P less than 0.005) subtypes. 4. Selective antagonists at 5-HT2 (ketanserin, mianserin, MDL 11939) and 5-HT3 (MDL 72222) sites were totally devoid of inhibitory activity on the 5-HT-induced contraction, an observation which agreed with the agonist data and further excluded activation of these receptors. In contrast, the 5-HT1-like/5-HT2 antagonist methiothepin and the non-selective 5-HT1D compound metergoline inhibited with high affinity the contraction induced by 5-HT with respective pA2 values of 8.55 +/- 0.16 and 6.88 +/- 0.05. This contractile response was, however, insensitive to 5-HT1B (propranolol) and 5-HT1C (mesulergine, mianserin) antagonists.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2043924

  8. Effects of MDMA and related analogs on plasma 5-HT: relevance to 5-HT transporters in blood and brain.

    PubMed

    Yubero-Lahoz, Samanta; Ayestas, Mario A; Blough, Bruce E; Partilla, John S; Rothman, Richard B; de la Torre, Rafael; Baumann, Michael H

    2012-01-15

    (±)-3,4-Methylenedioxymethamphetamine (MDMA) is an illicit drug that evokes transporter-mediated release of serotonin (5-HT) in the brain. 5-HT transporter (SERT) proteins are also expressed in non-neural tissues (e.g., blood), and evidence suggests that MDMA targets platelet SERT to increase plasma 5-HT. Here we tested two hypotheses related to the effects of MDMA on circulating 5-HT. First, to determine if MDMA metabolites might contribute to actions of the drug in vivo, we used in vitro microdialysis in rat blood specimens to examine the effects of MDMA and its metabolites on plasma 5-HT. Second, to determine whether effects of MDMA on plasma 5-HT might be used as an index of central SERT activity, we carried out in vivo microdialysis in blood and brain after intravenous MDMA administration. The in vitro results show that test drugs evoke dose-related increases in plasma 5-HT ranging from two- to sevenfold above baseline, with MDMA and its metabolite, (±)-3,4-methylenedioxyamphetamine (MDA), producing the largest effects. The ability of MDMA and related analogs to elevate plasma 5-HT is correlated with their potency as SERT substrates in rat brain synaptosomes. The in vivo results reveal that MDMA causes concurrent increases in extracellular 5-HT in blood and brain, but there are substantial individual differences in responsiveness to the drug. Collectively, our findings indicate that MDMA and its metabolites increase plasma 5-HT by a SERT-dependent mechanism, and suggest the possibility that measures of evoked 5-HT release in blood may reflect central SERT activity.

  9. Amelioration of hypoxia-induced striatal 5-HT(2A) receptor, 5-HT transporter and HIF1 alterations by glucose, oxygen and epinephrine in neonatal rats.

    PubMed

    Anju, T R; Paulose, C S

    2011-09-20

    Alterations in neurotransmitters and its receptors expression induce brain injury during neonatal hypoxic insult. Molecular processes regulating the serotonergic receptors play an important role in the control of respiration under hypoxic insult. The present study focused on the serotonergic regulation of neonatal hypoxia and its resuscitation methods. Receptor binding assays and gene expression studies were done to evaluate the changes in 5HT(2A) receptors and its transporter in the corpus striatum of hypoxic neonatal rats and hypoxic rats resuscitated with glucose, oxygen and epinephrine. Total 5HT and 5HT(2A) receptor number was increased in hypoxic neonates along with an up regulation of 5HT(2A) receptor and 5HT transporter gene. The enhanced striatal 5HT(2A) receptors modulate the ventilatory response to hypoxia. Immediate glucose resuscitation was found to ameliorate the receptor and transporter alterations. Hypoxia induced ATP depletion mediated reduction in blood glucose levels can be encountered by glucose administration and oxygenation helps in overcoming the anaerobic condition. The adverse effect of immediate oxygenation and epinephrine supplementation was also reported. This has immense clinical significance in establishing a proper resuscitation for the management of neonatal hypoxia.

  10. PET imaging of the serotonin transporter and 5HT1A receptor in alcohol dependence

    PubMed Central

    Martinez, Diana; Slifstein, Mark; Gil, Roberto; Hwang, Dah-Ren; Huang, Yiyun; Perez, Audrey; Frankle, W. Gordon; Laruelle, Marc; Krystal, John; Abi-Dargham, Anissa

    2009-01-01

    Background Rodent models as well as studies in humans have suggested alterations in serotonin (5HT) innervation and transmission in early onset genetically determined or type II alcoholism. This study examines two indices of serotonergic transmission, 5HT transporter levels and 5-HT1A availability, in vivo, in type II alcoholism. This is the first report of combined tracers for pre and post-synaptic serotonergic transmission in the same alcoholic subjects and the first study of 5HT1A receptors in alcoholism. Method Fourteen alcohol dependent subjects were scanned (11 with both tracers, 1 with [11C]DASB only and two with [11C]WAY100635 only). Twelve healthy controls (HC) subjects were scanned with [11C]DASB and another 13 were scanned with [11C]WAY100635. Binding Potential (BPp, mL/cm3) and the specific to nonspecific partition coefficient (BPND, unitless) were derived for both tracers using 2 tissue compartment model and compared to HC across different brain regions. Relationships to severity of alcoholism were assessed. Results No significant differences were observed in regional BPp or BPND between patients and controls in any of the regions examined. No significant relationships were observed between regional 5HT transporter availability, 5-HT1A availability, and disease severity with the exception of a significant negative correlation between SERT and years of dependence in amygdala and insula. Conclusion This study did not find alterations in measures of 5-HT1A or 5HT transporter levels in patients with type II alcoholism. PMID:18962444

  11. Characterization of 5-HT1D receptor binding sites in post-mortem human brain cortex.

    PubMed Central

    Martial, J; de Montigny, C; Cecyre, D; Quirion, R

    1991-01-01

    The present study provides further evidence for the presence of serotonin1D (5-HT1D) receptors in post-mortem human brain. Receptor binding parameters in temporal cortex homogenates were assessed using [3H]5-HT in the presence of 100 nM 8-OH-DPAT, 1 microM propranolol and 1 microM mesulergine to prevent labelling of the 5-HT1A, 5-HT1B and 5-HT1C sites, respectively. Under these conditions, [3H]5-HT apparently bound to a class of high affinity (Kd = 5.0 +/- 1.0 nM) low capacity (Bmax = 96 +/- 23 fmol/mg protein) sites. In competition experiments, 5-HT and 5-carboxyamidotryptamine (5-CT), as well as ergotamine, lysergic acid, sumatriptan and RU-24969 exhibited high affinity for these sites. This pharmacological profile is concordant with the ligand selectivity pattern reported for 5-HT1D receptors in other species and thus provides further evidence for its existence in human temporal cortex. In addition, the competition profile of some ligands, particularly of unlabelled 5-HT, 5-CT and ergotamine, revealed the existence of a lower affinity binding site. The latter suggests receptor heterogeneity or the presence of a lower affinity state of 5-HT1D receptors. PMID:1911737

  12. Regulation of extrasynaptic 5-HT by serotonin reuptake transporter function in 5-HT-absorbing neurons underscores adaptation behavior in Caenorhabditis elegans.

    PubMed

    Jafari, Gholamali; Xie, Yusu; Kullyev, Andrey; Liang, Bin; Sze, Ji Ying

    2011-06-15

    Serotonin [5-hydroxytryptamine (5-HT)]-absorbing neurons use serotonin reuptake transporter (SERT) to uptake 5-HT from extracellular space but do not synthesize it. While 5-HT-absorbing neurons have been identified in diverse organisms from Caenorhabditis elegans to humans, their function has not been elucidated. Here, we show that SERT in 5-HT-absorbing neurons controls behavioral response to food deprivation in C. elegans. The AIM and RIH interneurons uptake 5-HT released from chemosensory neurons and secretory neurons. Genetic analyses suggest that 5-HT secreted by both synaptic vesicles and dense core vesicles diffuse readily to the extrasynaptic space adjacent to the AIM and RIH neurons. Loss of mod-5/SERT function blocks the 5-HT absorption. mod-5/SERT mutants have been shown to exhibit exaggerated locomotor response to food deprivation. We found that transgenic expression of MOD-5/SERT in the 5-HT-absorbing neurons fully corrected the exaggerated behavior. Experiments of cell-specific inhibition of synaptic transmission suggest that the synaptic release of 5-HT from the 5-HT-absorbing neurons is not required for this behavioral modulation. Our data point to the role of 5-HT-absorbing neurons as temporal-spatial regulators of extrasynaptic 5-HT. Regulation of extrasynaptic 5-HT levels by 5-HT-absorbing neurons may represent a fundamental mechanism of 5-HT homeostasis, integrating the activity of 5-HT-producing neurons with distant targets in the neural circuits, and could be relevant to some actions of selective serotonin reuptake inhibitors in humans.

  13. 5-HT1B autoreceptor regulation of serotonin transporter activity in synaptosomes

    PubMed Central

    Hagan, Catherine E.; McDevitt, Ross A.; Liu, Yusha; Furay, Amy R.; Neumaier, John F.

    2012-01-01

    Serotonin-1B (5-HT1B) autoreceptors are located in serotonin (5-HT) terminals along with serotonin transporters (SERT), and play a critical role in autoregulation of serotonergic neurotransmission, and are implicated in disorders of serotonergic function, particularly emotional regulation. SERT modulates serotonergic neurotransmission by high-affinity reuptake of 5-HT. Alterations in SERT activity are associated with increased risk for depression and anxiety. Several neurotransmitter receptors are known to regulate SERT Km and Vmax, and previous work suggests that 5-HT1B autoreceptors may regulate 5-HT reuptake, in addition to modulating 5-HT release and synthesis. We used rotating disk electrode voltammetry to investigate 5-HT1B autoreceptor regulation of SERT-mediated 5-HT uptake into synaptosomes. The selective 5-HT1B antagonist SB224289 decreased SERT activity in synaptosomes prepared from wild-type but not 5-HT1B knockout mice, whereas SERT uptake was enhanced after pre-treatment with the selective 5-HT1B agonist CP94253. Furthermore, SERT activity varies as a function of 5-HT1B receptor expression—specifically, genetic deletion of 5-HT1B decreased SERT function, while viral-mediated overexpression of 5-HT1B autoreceptors in rat raphe neurons increased SERT activity in rat hippocampal synaptosomes. Considered collectively, these results provide evidence that 5-HT1B autoreceptors regulate SERT activity. Since SERT clearance rate varies as a function of 5-HT1B autoreceptor expression levels and is modulated by both activation and inhibition of 5-HT1B autoreceptors, this dynamic interaction may be an important mechanism of serotonin autoregulation with therapeutic implications. PMID:22961814

  14. Quantitation of 5HT3 receptors in forebrain of serotonin transporter deficient mice.

    PubMed

    Mössner, R; Schmitt, A; Hennig, T; Benninghoff, J; Gerlach, M; Riederer, P; Deckert, J; Lesch, K P

    2004-01-01

    Mice deficient in the serotonin transporter (5HTT) display highly elevated extracellular 5HT levels. 5HT exerts ist effects via at least fourteen different cloned 5HT receptors located pre- and postsynaptically. In contrast to the other 5HT receptors, the 5HT3 receptor is a ionotropic receptor with ligand-gated cation channel function. Since G-protein-coupled 5HT receptors show extensive adaptive changes in 5HTT-deficient mice, we investigated whether 5HT3 receptors are also altered in these mice. Using quantitative autoradiography, we found that 5HT3 receptors are upregulated in frontal cortex (+46%), parietal cortex (+42%), and in stratum oriens of the CA3 region of the hippocampus (+18%) of 5HTT knockout mice. Changes in 5HT3 receptor mRNA expression, as determined by quantitative in situ hybridisation, were less pronounced. The adaptive changes of 5HT3 receptor expression constitute a part of the complex regulatory pattern of 5HT receptors in 5HTT knockout mice.

  15. The binding characteristics and orientation of a novel radioligand with distinct properties at 5-HT3A and 5-HT3AB receptors

    PubMed Central

    Thompson, Andrew J.; Verheij, Mark H.P.; Verbeek, Joost; Windhorst, Albert D.; de Esch, Iwan J.P.; Lummis, Sarah C.R.

    2014-01-01

    VUF10166 (2-chloro-3-(4-methyl piperazin-1-yl)quinoxaline) is a ligand that binds with high affinity to 5-HT3 receptors. Here we synthesise [3H]VUF10166 and characterise its binding properties at 5-HT3A and 5-HT3AB receptors. At 5-HT3A receptors [3H]VUF10166 displayed saturable binding with a Kd of 0.18 nM. Kinetic measurements gave monophasic association (6.25 × 107 M−1 min−1) and dissociation (0.01 min−1) rates that yielded a similar Kd value (0.16 nM). At 5-HT3AB receptors two association (6.15 × 10−7, 7.23 M−1 min−1) and dissociation (0.024, 0.162 min−1) rates were seen, yielding Kd values (0.38 nM and 22 nM) that were consistent with values obtained in saturation (Kd = 0.74 nM) and competition (Ki = 37 nM) binding experiments respectively. At both receptor types, specific binding was inhibited by classical 5-HT3 receptor-selective orthosteric ligands (5-HT, allosetron, d-tubocurarine, granisetron, mCPBG, MDL72222, quipazine), but not by non-competitive antagonists (bilobalide, ginkgolide B, picrotoxin) or competitive ligands of other Cys-loop receptors (ACh, bicuculline, glycine, gabazine). To explore VUF10166 ligand–receptor interactions we used in silico modelling and docking, and tested the predictions using site directed mutagenesis. The data suggest that VUF10166 adopts a similar orientation to 5-HT3 receptor agonists bound in AChBP (varenicline) and 5HTBP (5-HT) crystal structures. PMID:25174552

  16. The relation of developmental changes in brain serotonin transporter (5HTT) and 5HT1A receptor binding to emotional behavior in female rhesus monkeys: effects of social status and 5HTT genotype.

    PubMed

    Embree, M; Michopoulos, V; Votaw, J R; Voll, R J; Mun, J; Stehouwer, J S; Goodman, M M; Wilson, M E; Sánchez, M M

    2013-01-03

    The goal of the present study was to examine how social subordination stress and 5HTT polymorphisms affect the development of brain serotonin (5HT) systems during the pubertal transition in female rhesus monkeys. We also examined associations with developmental changes in emotional reactivity in response to a standardized behavioral test, the Human Intruder (HI). Our findings provide the first longitudinal evidence of developmental increases in 5HT1A receptor and 5HTT binding in the brain of female primates from pre- to peripuberty. The increase in 5HT1A BP(ND) in these socially housed female rhesus monkeys is a robust finding, occurring across all groups, regardless of social status or 5HTT genotype, and occurring in the left and right hemispheres of all prefrontal regions studied, as well as the amygdala, hippocampus, hypothalamus, and raphe nuclei. 5HTT BP(ND) also showed an increase with age in raphe, anterior cingulate cortex, and dorsolateral prefrontal cortex. These changes in brain 5HT systems take place as females establish more adult-like patterns of social behavior, as well as during the HI paradigm. Indeed, the main developmental changes in behavior during the HI (increase in freezing and decrease in submission/appeasement) were related to neurodevelopmental increases in 5HT1A receptors and 5HTT, because the associations between these behaviors and 5HT endpoints emerge at peripuberty. We detected an effect of social status on 5HT1A BP(ND) in the hypothalamus and on 5HTT BP(ND) in the orbitofrontal cortex, with subordinates showing higher BP(ND) than dominants in both cases during the pubertal transition. No main effects of 5HTT genotype were observed for 5HT1A or 5HTT BP(ND). Our findings indicate that adolescence in female rhesus monkeys is a period of central 5HT reorganization, partly influenced by exposure to the social stress of subordination, that likely functions to integrate adrenal and gonadal systems and shape the behavioral response to

  17. A quantitative model of amphetamine action on the 5-HT transporter

    PubMed Central

    Sandtner, Walter; Schmid, Diethart; Schicker, Klaus; Gerstbrein, Klaus; Koenig, Xaver; Mayer, Felix P; Boehm, Stefan; Freissmuth, Michael; Sitte, Harald H

    2014-01-01

    Background and Purpose Amphetamines bind to the plasmalemmal transporters for the monoamines dopamine (DAT), noradrenaline (NET) and 5-HT (SERT); influx of amphetamine leads to efflux of substrates. Various models have been proposed to account for this amphetamine-induced reverse transport in mechanistic terms. A most notable example is the molecular stent hypothesis, which posits a special amphetamine-induced conformation that is not likely in alternative access models of transport. The current study was designed to evaluate the explanatory power of these models and the molecular stent hypothesis. Experimental Approach Xenopus laevis oocytes and HEK293 cells expressing human (h) SERT were voltage-clamped and exposed to 5-HT, p-chloroamphetamine (pCA) or methylenedioxyamphetamine (MDMA). Key Results In contrast to the currents induced by 5-HT, pCA-triggered currents through SERT decayed slowly in Xenopus laevis oocytes once the agonist was removed (consistent with the molecular stent hypothesis). However, when SERT was expressed in HEK293 cells, currents induced by 3 or 100 μM pCA decayed 10 or 100 times faster, respectively, after pCA removal. Conclusions and Implications This discrepancy in decay rates is inconsistent with the molecular stent hypothesis. In contrast, a multistate version of the alternative access model accounts for all the observations and reproduces the kinetic parameters extracted from the electrophysiological recordings. A crucial feature that explains the action of amphetamines is their lipophilic nature, which allows for rapid diffusion through the membrane. PMID:24251585

  18. Radioligand binding evidence implicates the brain 5-HT2 receptor as a site of action for LSD and phenylisopropylamine hallucinogens.

    PubMed

    Titeler, M; Lyon, R A; Glennon, R A

    1988-01-01

    Alterations in brain serotonergic function have been implicated in the mechanism of action of LSD, mescaline, and other similarly acting hallucinogenic drugs of abuse such as STP (2,5-dimethoxyphenylisopropylamine; DOM). In order to test the hypothesis that the mechanism of action of LSD and phenylisopropylamine hallucinogens is through stimulation of a specific brain serotonin receptor sub-type, the affinities of these compounds for radiolabelled 5-HT2, 5-HT1A, 5-HT1B, and 5-HT1C receptors have been determined using recently developed in vitro radioligand binding methodologies. The 5-HT2 receptor was labelled with the agonist/hallucinogen radioligand 3H-DOB (4-bromo-2,5-dimethoxyphenylisopropylamine). The 5-HT1A, 5-HT1B, and 5-HT1C receptors were labelled with 3H-OH-DPAT, 3H-5-HT, and 3H-mesulergine, respectively. In general, the phenylisopropylamines displayed 10-100 fold higher affinities for the 5-HT2 receptor than for the 5-HT1C receptor and 100-1000 fold higher affinities for the 5-HT2 receptor than for the 5-HT1A or 5-HT1B receptor. There was a strong correlation between hallucinogenic potencies and 5-HT2 receptor affinities of the phenylisopropylamines (r = 0.90); the correlation coefficients for the 5-HT1A, 5-HT1B, and 5-HT1C were 0.73, 0.85, and 0.78, respectively. Because there is no evidence that 5-HT1A-selective or 5-HT1B-selective agonists are hallucinogenic and because the phenylisopropylamines are potent hallucinogens, a 5-HT2 receptor interaction is implicated and supports our previous suggestions to this effect. A secondary role for 5-HT1C receptors cannot be discounted at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Palonosetron-5-HT3 Receptor Interactions As Shown by a Binding Protein Cocrystal Structure.

    PubMed

    Price, Kerry L; Lillestol, Reidun K; Ulens, Chris; Lummis, Sarah C R

    2016-12-21

    Palonosetron is a potent 5-HT3 receptor antagonist and an effective therapeutic agent against emesis. Here we identify the molecular determinants of compound recognition in the receptor binding site by obtaining a high resolution structure of palonosetron bound to an engineered acetylcholine binding protein that mimics the 5-HT3 receptor binding site, termed 5-HTBP, and by examining the potency of palonosetron in a range of 5-HT3 receptors with mutated binding site residues. The structural data indicate that palonosetron forms a tight and effective wedge in the binding pocket, made possible by its rigid tricyclic ring structure and its interactions with binding site residues; it adopts a binding pose that is distinct from the related antiemetics granisetron and tropisetron. The functional data show many residues previously shown to interact with agonists and antagonists in the binding site are important for palonosetron binding, and indicate those of particular importance are W183 (a cation-π interaction and a hydrogen bond) and Y153 (a hydrogen bond). This information, and the availability of the structure of palonosetron bound to 5-HTBP, should aid the development of novel and more efficacious drugs that act via 5-HT3 receptors.

  20. Benzothiazoles as probes for the 5HT1A receptor and the serotonin transporter (SERT): a search for new dual-acting agents as potential antidepressants.

    PubMed

    Zhu, Xue Y; Etukala, Jagan R; Eyunni, Suresh V K; Setola, Vincent; Roth, Bryan L; Ablordeppey, Seth Y

    2012-07-01

    The synthesis and evaluation of several benzothiazole-based compounds are described in an attempt to identify novel dual-acting 5HT(1A) receptor and SERT inhibitors as new antidepressants. Binding affinities at the 5HT(1A) receptor and the serotonin transporter do not appear to be congruent and other areas of the binding sites would need to be explored in order to improve binding simultaneously at both sites. Compounds 20 and 23 show moderate binding affinity at the 5HT(1A) receptor and the SERT site and thus, have the potential to be further explored as dual-acting agents. In addition, compound 20 binds with low affinity to the dopamine transporter (DAT), the norepinephrine transporter (NET) and 5HT(2C) receptor, which are desirable properties as selectivity for SERT (and not DAT or NET) is associated with an absence of cardiovascular side effects.

  1. Application of Quantitative Structure–Activity Relationship Models of 5-HT1A Receptor Binding to Virtual Screening Identifies Novel and Potent 5-HT1A Ligands

    PubMed Central

    2015-01-01

    The 5-hydroxytryptamine 1A (5-HT1A) serotonin receptor has been an attractive target for treating mood and anxiety disorders such as schizophrenia. We have developed binary classification quantitative structure–activity relationship (QSAR) models of 5-HT1A receptor binding activity using data retrieved from the PDSP Ki database. The prediction accuracy of these models was estimated by external 5-fold cross-validation as well as using an additional validation set comprising 66 structurally distinct compounds from the World of Molecular Bioactivity database. These validated models were then used to mine three major types of chemical screening libraries, i.e., drug-like libraries, GPCR targeted libraries, and diversity libraries, to identify novel computational hits. The five best hits from each class of libraries were chosen for further experimental testing in radioligand binding assays, and nine of the 15 hits were confirmed to be active experimentally with binding affinity better than 10 μM. The most active compound, Lysergol, from the diversity library showed very high binding affinity (Ki) of 2.3 nM against 5-HT1A receptor. The novel 5-HT1A actives identified with the QSAR-based virtual screening approach could be potentially developed as novel anxiolytics or potential antischizophrenic drugs. PMID:24410373

  2. Caulis Sinomenii extracts activate DA/NE transporter and inhibit 5HT transporter.

    PubMed

    Zhao, Gang; Bi, Cheng; Qin, Guo-Wei; Guo, Li-He

    2009-08-01

    Caulis Sinomenii (QFT) has analgesic, sedative, and anxiolytic-like actions, and is proven effective for improving drug dependence that is known to be associated with abnormal monoaminergic transmission. We assessed whether QFT would be biologically active in functionally regulating monoamine transporters using CHO cells expressing dopamine transporter (DAT), norepinephrine transporter (NET), or serotonin transporter (SERT) (i.e. D8, N1, or S6 cells, respectively). Here, we showed that its primary extracts, such as QA, QC, QE, QD, and QB (QFT ethanol, chloroform, ethyl acetate, alkaloid-free chloroform, and alkaloid-containing chloroform extract, respectively), and secondary extracts, such as QE-2, - 3, - 5, - 7, QD-1, - 2, - 3, - 4, - 5, and QB-1, - 2, - 3, - 4, - 5 (fractioned from QE, QD, and QB, respectively), in differing degrees, either increased DA/ NE uptake by corresponding D8/N1 cells or decreased 5HT uptake by S6 cells; wherein, QE-2, QD-3, and QE-7 were potent DA/NE uptake activators while both QE-7 and QB-5 were potent 5HT uptake inhibitors. Furthermore, the enhancement of DA/NE uptake was dependent of DAT/NET activity, and the inhibition of 5HT uptake was typical of competition. Thus, QFT extracts, especially QE-2 and QE-7 (both with stronger potencies), are novel monoamine transporter modulators functioning as DAT/ NET activators and/or SERT inhibitors, and would likely improve neuropsychological disorders through regulating monoamine transporters.

  3. 3D Pharmacophore, hierarchical methods, and 5-HT4 receptor binding data.

    PubMed

    Varin, Thibault; Saettel, Nicolas; Villain, Jonathan; Lesnard, Aurelien; Dauphin, François; Bureau, Ronan; Rault, Sylvain

    2008-10-01

    5-Hydroxytryptamine subtype-4 (5-HT(4)) receptors have stimulated considerable interest amongst scientists and clinicians owing to their importance in neurophysiology and potential as therapeutic targets. A comparative analysis of hierarchical methods applied to data from one thousand 5-HT(4) receptor-ligand binding interactions was carried out. The chemical structures were described as chemical and pharmacophore fingerprints. The definitions of indices, related to the quality of the hierarchies in being able to distinguish between active and inactive compounds, revealed two interesting hierarchies with the Unity (1 active cluster) and pharmacophore fingerprints (4 active clusters). The results of this study also showed the importance of correct choice of metrics as well as the effectiveness of a new alternative of the Ward clustering algorithm named Energy (Minimum E-Distance method). In parallel, the relationship between these classifications and a previously defined 3D 5-HT(4) antagonist pharmacophore was established.

  4. 5-HT system and cognition.

    PubMed

    Meneses, A

    1999-12-01

    The study of 5-hydroxytryptamine (5-HT) system has benefited from the identification, classification and cloning of multiple 5-HT receptors (5-HT1 to 5-HT7). Growing evidence suggests that 5-HT is important in learning and memory and all its receptors might be implicated in this. Actually, 5-HT pathways, 5-HT reuptake site/transporter complex and 5-HT receptors show regional distribution in brain areas implicated in learning and memory. Likewise, the stimulation or blockade of presynaptic 5-HT1A, 5-HT1B, 5-HT(2A/2C) and 5-HT3 receptors, postsynaptic 5-HT(2B/2C) and 5-HT4 receptors and 5-HT uptake/transporter sites modulate these processes. Available evidence strongly suggests that the 5-HT system may be important in normal function, the treatment and/or pathogenesis of cognitive disorders. Further investigation will help to specify the 5-HT system nature involvement in cognitive processes, pharmacotherapies, their mechanisms and action sites and to determine under which conditions they could operate. In this regard, it is probable that selective drugs with agonists, neutral antagonist, agonists or inverse agonist properties for 5-HT1A, 5-HT(1B/1D), 5-HT(2A/2B/2C), 5-HT4 and 5-HT7 receptors could constitute a new therapeutic opportunity for learning and memory alterations.

  5. New 1-arylindoles based serotonin 5-HT7 antagonists. Synthesis and binding evaluation studies.

    PubMed

    Sagnes, Charlène; Fournet, Guy; Satala, Grzegorz; Bojarski, Andrzej J; Joseph, Benoît

    2014-03-21

    Based on 5-HT1A and 5-HT7 ligand MR25003 scaffold, a new series of 1-aryl indole analogues were prepared and evaluated against 5-HT7 receptors. Modulations of aryl moieties provided a large number of new indolic derivatives. Most of compounds tested have displayed 5-HT7 affinity in the nanomolar range. Among them, 1-(naphthyl)indole derivative 3p (Ki (5-HT7) = 4.5 nM) showed also a good selectivity over 5-HT1A, 5-HT2A and 5-HT6 receptors. This compound was pharmacology characterized as an antagonist.

  6. The psychostimulant d-threo-(R,R)-methylphenidate binds as an agonist to the 5HT(1A) receptor.

    PubMed

    Markowitz, J S; DeVane, C L; Ramamoorthy, S; Zhu, Hao-Jie

    2009-02-01

    The present study was undertaken to determine whether d-threo-(R,R)-methylphenidate (MPH) was exerting binding activity as an agonist or antagonist of 5-HT1A and 5-HT2B receptors. [35S]guanosine5'[gamma-thio]triphosphate ([35S]GTPgammaS) binding assay and field-stimulated Guinea pig ileum assay were used to determine 5-HT(1A) receptor agonism and antagonism activity of d-threo-(R,R)-MPH. The results suggested d-threo-(R,R)-MPH induced 5-HT(1A) receptor agonist activity at 100 microM. The Guinea pig ileum functional assay showed that d-threo-(R,R)-MPH produced agonist-like reduction of neurogenic twitch with an EC50 5.65 +/- 0.36 microM. At 30 microM concentrations, d-threo-(R,R)-MPH produced 171 +/- 4.24% of the relaxation relative to that caused by 0.12 microM 8-OH-DPAT. However, d-threo-(R,R)-MPH exhibited no significant pharmacological activity in rat stomach fundus 5-HT(2B) receptor functional assay. Thus, d-threo-(R,R)-MPH appears to act as a selective 5-HT(1A) receptor agonist in vitro. It is speculated that the activation of 5-HT(1A) receptor might play a partial role in d-threo-(R,R)-MPH mediated dopamine (DA) release in the brain.

  7. Antidepressant activity: contribution of brain microdialysis in knock-out mice to the understanding of BDNF/5-HT transporter/5-HT autoreceptor interactions

    PubMed Central

    Gardier, Alain M.

    2013-01-01

    Why antidepressants vary in terms of efficacy is currently unclear. Despite the leadership of selective serotonin reuptake inhibitors (SSRIs) in the treatment of depression, the precise neurobiological mechanisms involved in their therapeutic action are poorly understood. A better knowledge of molecular interactions between monoaminergic system, pre- and post-synaptic partners, brain neuronal circuits and regions involved may help to overcome limitations of current treatments and identify new therapeutic targets. Intracerebral in vivo microdialysis (ICM) already provided important information about the brain mechanism of action of antidepressants first in anesthetized rats in the early 1990s, and since then in conscious wild-type or knock-out mice. The principle of ICM is based on the balance between release of neurotransmitters (e.g., monoamines) and reuptake by selective transporters [e.g., serotonin transporter for serotonin 5-hydroxytryptamine (5-HT)]. Complementary to electrophysiology, this technique reflects pre-synaptic monoamines release and intrasynaptic events corresponding to ≈80% of whole brain tissue content. The inhibitory role of serotonergic autoreceptors infers that they limit somatodendritic and nerve terminal 5-HT release. It has been proposed that activation of 5-HT1A and 5-HT1B receptor sub-types limits the antidepressant-like activity of SSRIs. This hypothesis is based partially on results obtained in ICM experiments performed in naïve, non-stressed rodents. The present review will first remind the principle and methodology of ICM performed in mice. The crucial need of developing animal models that display anxiety and depression-like behaviors, neurochemical and brain morphological phenotypes reminiscent of these mood disorders in humans, will be underlined. Recently developed genetic mouse models have been generated to independently manipulate 5-HT1A auto and heteroreceptors and ICM helped to clarify the role of the pre-synaptic component

  8. Regional distribution of 5-HT transporters in the brain of wild type and 'Purkinje cell degeneration' mutant mice: a quantitative autoradiographic study with [3H]citalopram.

    PubMed

    Le Marec, N; Hébert, C; Amdiss, F; Botez, M I; Reader, T A

    1998-09-01

    The neurological mutant 'Purkinje cell degeneration' (pcd) is characterized by a primary degeneration of Purkinje cells, as well as by retrograde and secondary partial degeneration of cerebellar granule cells and inferior olivary neurons, and can be considered as an animal model of human degenerative ataxias. The serotonin (5-HT) innervation was examined in wild type and pcd mice, by quantifying 5-HT uptake sites, or transporters, using [3H]citalopram binding autoradiography. In both wild type and pcd mutants, the highest densities of 5-HT transporters were in mesencephalic and rostral pontine regions, in limbic structures, in hypothalamus and in discrete thalamic divisions, while the lowest labelling was found in cerebellum and brainstem reticular formation. In pcd mice, although [3H]citalopram labelling was higher in cerebellar cortex and deep cerebellar nuclei, when binding densities were corrected for surface area, the up-regulation of 5-HT transporters was present only in deep cerebellar nuclei. Also, higher labelling was found in nuclei raphe dorsalis and medialis, in ventral divisions of rostral neostriatum, caudal neostriatum, rostral globus pallidus, posteromedial amygdaloid nucleus, septum, olfactory tubercles, vertical limb of Broca's diagonal band, periventricular, latero-ventral and medio-ventral thalamic nuclei, medial geniculate nucleus, anterior hypothalamus and entorhinal cortex. The results indicate a relative integrity of the 5-HT innervation, but with a reorganization of serotoninergic terminals in the cerebellum, in particular in the deep cerebellar nuclei. This suggests that in progressive cerebellar degeneration, as found in the pcd mutant, the modified 5-HT system may still participate in motor functions by exerting an overall modulation of excitatory amino acid neurotransmission, but the availability of 5-HT may be altered in defined brain targets, as is the case for other spontaneous cerebellar mutants, in particular for the 'Lurcher

  9. Discovery of SMP-304, a novel benzylpiperidine derivative with serotonin transporter inhibitory activity and 5-HT1A weak partial agonistic activity showing the antidepressant-like effect.

    PubMed

    Yoshinaga, Hidefumi; Masumoto, Shuji; Koyama, Koji; Kinomura, Naoya; Matsumoto, Yuji; Kato, Taro; Baba, Satoko; Matsumoto, Kenji; Horisawa, Tomoko; Oki, Hitomi; Yabuuchi, Kazuki; Kodo, Toru

    2017-01-01

    We report the discovery of a novel benzylpiperidine derivative with serotonin transporter (SERT) inhibitory activity and 5-HT1A receptor weak partial agonistic activity showing the antidepressant-like effect. The 3-methoxyphenyl group and the phenethyl group of compound 1, which has weak SERT binding activity, but potent 5-HT1A binding activity, were optimized, leading to compound 35 with potent and balanced dual SERT and 5-HT1A binding activity, but also potent CYP2D6 inhibitory activity. Replacement of the methoxy group in the left part of compound 35 with a larger alkoxy group, such as ethoxy, isopropoxy or methoxy-ethoxy group ameliorated CYP2D6 inhibition, giving SMP-304 as a candidate. SMP-304 with serotonin uptake inhibitory activity and 5-HT1A weak partial agonistic activity, which could work as a 5-HT1A antagonist, displayed faster onset of antidepressant-like effect than a representative SSRI paroxetine in an animal model.

  10. Inactivation of 5HT transport in mice: modeling altered 5HT homeostasis implicated in emotional dysfunction, affective disorders, and somatic syndromes.

    PubMed

    Lesch, K P; Mössner, R

    2006-01-01

    Animal models have not only become an essential tool for investigating the neurobiological function of genes that are involved in the etiopathogenesis of human behavioral and psychiatric disorders but are also fundamental in the development novel therapeutic strategies. As an example, inactivation of the serotonin (5HT) transporter (5Htt, Slc6a4) gene in mice expanded our view of adaptive 5HT uptake regulation and maintenance of 5HT homeostasis in the developing human brain and molecular processes underlying anxiety-related traits, as well as affective spectrum disorders including depression. 5Htt-deficient mice have been employed as a model complementary to direct studies of genetically complex traits and disorders, with important findings in biochemical, morphological, behavioral, and pharmacological areas. Based on growing evidence for a critical role of the 5HTT in the integration of synaptic connections in the rodent, nonhuman primate, and human brain during critical periods of development and adult life, more in-depth knowledge of the molecular mechanisms implicated in these fine-tuning processes is currently evolving. Moreover, demonstration of a joint influence of the 5HTT variation and environmental sources during early brain development advanced our understanding of the mechanism of genexgene and genexenvironment interactions in the developmental neurobiology of anxiety and depression. Lastly, imaging techniques, which become increasingly elaborate in displaying the genomic influence on brain system activation in response to environmental cues, have provided the means to bridge the gap between small effects of 5HTT variation and complex behavior, as well as psychopathological dimensions. The combination of elaborate genetic, epigenetic, imaging, and behavioral analyses will continue to generate new insight into 5HTT's role as a master control gene of emotion regulation.

  11. Autoradiographic characterization of (+-)-1-(2,5-dimethoxy-4-( sup 125 I) iodophenyl)-2-aminopropane (( sup 125 I)DOI) binding to 5-HT2 and 5-HT1c receptors in rat brain

    SciTech Connect

    Appel, N.M.; Mitchell, W.M.; Garlick, R.K.; Glennon, R.A.; Teitler, M.; De Souza, E.B. )

    1990-11-01

    The 5-HT2 (serotonin) receptor has traditionally been labeled with antagonist radioligands such as (3H)ketanserin and (3H)spiperone, which label both agonist high-affinity (guanyl nucleotide-sensitive) and agonist low-affinity (guanyl nucleotide-insensitive) states of this receptor. The hallucinogen 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) is an agonist which labels the high-affinity guanyl nucleotide-sensitive state of brain 5-HT2 receptors selectively. In the present study, conditions for autoradiographic visualization of (+/-)-(125I)DOI-labeled 5-HT2 receptors were optimized and binding to slide-mounted sections was characterized with respect to pharmacology, guanyl nucleotide sensitivity and anatomical distribution. In slide-mounted rat brain sections (+/-)-(125I)DOI binding was saturable, of high affinity (KD approximately 4 nM) and displayed a pharmacologic profile typical of 5-HT2 receptors. Consistent with coupling of 5-HT2 receptors in the high-affinity state to a guanyl nucleotide regulatory protein, (125I)DOI binding was inhibited by guanyl nucleotides but not by adenosine triphosphate. Patterns of autoradiographic distribution of (125I)DOI binding to 5-HT2 receptors were similar to those seen with (3H)ketanserin- and (125I)-lysergic acid diethylamide-labeled 5-HT2 receptors. However, the density of 5-HT2 receptors labeled by the agonist (125I)DOI was markedly lower (30-50%) than that labeled by the antagonist (3H)ketanserin. High densities of (125I)DOI labeling were present in olfactory bulb, anterior regions of cerebral cortex (layer IV), claustrum, caudate putamen, globus pallidus, ventral pallidum, islands of Calleja, mammillary nuclei and inferior olive. Binding in hippocampus, thalamus and hypothalamus was generally sparse.

  12. 5-Hydroxytryptamine (5-HT) Cellular Sequestration during Chronic Exposure Delays 5-HT3 Receptor Resensitization due to Its Subsequent Release*

    PubMed Central

    Hothersall, J. Daniel; Alexander, Amy; Samson, Andrew J.; Moffat, Christopher; Bollan, Karen A.; Connolly, Christopher N.

    2014-01-01

    The serotonergic synapse is dynamically regulated by serotonin (5-hydroxytryptamine (5-HT)) with elevated levels leading to the down-regulation of the serotonin transporter and a variety of 5-HT receptors, including the 5-HT type-3 (5-HT3) receptors. We report that recombinantly expressed 5-HT3 receptor binding sites are reduced by chronic exposure to 5-HT (IC50 of 154.0 ± 45.7 μm, t½ = 28.6 min). This is confirmed for 5-HT3 receptor-induced contractions in the guinea pig ileum, which are down-regulated after chronic, but not acute, exposure to 5-HT. The loss of receptor function does not involve endocytosis, and surface receptor levels are unaltered. The rate and extent of down-regulation is potentiated by serotonin transporter function (IC50 of 2.3 ± 1.0 μm, t½ = 3.4 min). Interestingly, the level of 5-HT uptake correlates with the extent of down-regulation. Using TX-114 extraction, we find that accumulated 5-HT remains soluble and not membrane-bound. This cytoplasmically sequestered 5-HT is readily releasable from both COS-7 cells and the guinea pig ileum. Moreover, the 5-HT level released is sufficient to prevent recovery from receptor desensitization in the guinea pig ileum. Together, these findings suggest the existence of a novel mechanism of down-regulation where the chronic release of sequestered 5-HT prolongs receptor desensitization. PMID:25281748

  13. Chronic betahistine co-treatment reverses olanzapine's effects on dopamine D₂ but not 5-HT2A/2C bindings in rat brains.

    PubMed

    Lian, Jiamei; Huang, Xu-Feng; Pai, Nagesh; Deng, Chao

    2015-01-02

    Olanzapine is widely prescribed for treating schizophrenia and other mental disorders, although it leads to severe body weight gain/obesity. Chronic co-treatment with betahistine has been found to significantly decrease olanzapine-induced weight gain; however, it is not clear whether this co-treatment affects the therapeutic effects of olanzapine. This study investigated the effects of chronic treatment of olanzapine and/or betahistine on the binding density of the serotonergic 5-HT2A (5-HT2AR) and 5-HT2C (5-HT2CR) receptors, 5-HT transporter (5-HTT), and dopaminergic D₂ receptors (D₂R) in the brain regions involved in antipsychotic efficacy, including the prefrontal cortex (PFC), cingulate cortex (Cg), nucleus accumbens (NAc), and caudate putamen (CPu). Rats were treated with olanzapine (1 mg/kg, t.i.d.) or vehicle for 3.5 weeks, and then olanzapine treatment was withdrawn for 19 days. From week 6, the two groups were divided into 4 groups (n=6) for 5 weeks' treatment: (1) olanzapine-only (1 mg/kg, t.i.d.), (2) betahistine-only (9.6 mg/kg, t.i.d.), (3) olanzapine and betahistine co-treatment (O+B), and (4) vehicle. Compared to the control, the olanzapine-only treatment significantly decreased the bindings of 5-HT2AR, 5-HT2CR, and 5-HTT in the PFC, Cg, and NAc. Similar changes were observed in the rats receiving the O+B co-treatment. The olanzapine-only treatment significantly increased the D₂R binding in the Cg, NAc, and CPu, while the betahistine-only treatment reduced D₂R binding. The co-treatment of betahistine reversed the D₂R bindings in the NAc and CPu that were increased by olanzapine. Therefore, chronic O+B co-treatment has similar effects on serotonin transmission as the olanzapine-only treatment, but reverses the D₂R that is up-regulated by chronic olanzapine treatment. The co-treatment maintains the therapeutic effects of olanzapine but decreases/prevents the excess weight gain.

  14. Reduced 5-HT(1B) receptor binding in the dorsal brain stem after cognitive behavioural therapy of major depressive disorder.

    PubMed

    Tiger, Mikael; Rück, Christian; Forsberg, Anton; Varrone, Andrea; Lindefors, Nils; Halldin, Christer; Farde, Lars; Lundberg, Johan

    2014-08-30

    Major depression is a significant contributor to the global burden of disease, and its pathophysiology is largely unknown. The serotonin hypothesis is, however, the model with most supporting data, although the details are only worked out to some extent. Recent clinical imaging measurements indeed imply a role in major depressive disorder (MDD) for the inhibitory serotonin autoreceptor 5-hydroxytryptamine1B (5-HT1B). The aim of the current study was to examine 5-HT1B receptor binding in the brain of MDD patients before and after psychotherapy. Ten patients with an ongoing untreated moderate depressive episode were examined with positron emission tomography (PET) and the 5-HT1B receptor selective radioligand [(11)C]AZ10419369, before and after treatment with internet-based cognitive behavioural therapy. All of the patients examined responded to treatment, and 70% were in remission by the time of the second PET measurement. A statistically significant 33% reduction of binding potential (BPND) was found in the dorsal brain stem (DBS) after treatment. No other significant changes in BPND were found. The DBS contains the raphe nuclei, which regulate the serotonin system. This study gives support for the importance of serotonin and the 5-HT1B receptor in the biological response to psychological treatment of MDD.

  15. Synthesis and molecular modeling of new 1-aryl-3-[4-arylpiperazin-1-yl]-1-propane derivatives with high affinity at the serotonin transporter and at 5-HT(1A) receptors.

    PubMed

    Orús, Lara; Pérez-Silanes, Silvia; Oficialdegui, Ana-M; Martínez-Esparza, Javier; Del Castillo, Juan-C; Mourelle, Marisa; Langer, Thierry; Guccione, Salvatore; Donzella, Giuseppina; Krovat, Eva M; Poptodorov, Konstantin; Lasheras, Berta; Ballaz, Santiago; Hervías, Isabel; Tordera, Rosa; Del Río, Joaquín; Monge, Antonio

    2002-09-12

    It has been proposed that 5-HT(1A) receptor antagonists augment the antidepressant efficacy of selective serotonin (5-HT) reuptake inhibitors. In a search toward new and efficient antidepressants, 1-(aryl)-3-[4-arylpiperazin-1-yl]-1-propane molecular hybrids were designed, synthesized, and evaluated for 5-HT reuptake inhibition and 5-HT(1A) receptor affinity. The design was based in coupling structural moieties related to inhibition of serotonin reuptake, such as benzo[b]thiophene derivatives to arylpiperazines, typical 5-HT(1A) receptor ligands. In binding studies, several compounds showed affinity at the 5-HT transporter and at 5-HT(1A) receptors. Molecular modeling studies predicted the pharmacophore elements required for high affinity binding and the features that enable to discriminate between agonist, partial agonist, or antagonist action at 5-HT(1A) receptors and 5-HT transporter inhibition. Solvent interactions in desolvation prior to the binding step along with enthalpy and enthropy compensations might be responsible to explain agonist, partial agonist, and antagonist character. Hydrogen-bonding capability seems to be important to break hydrogen interhelical hydrogen bonds or alternatively to form other bonds upon ligand binding. Partial agonists and antagonists are unable to do this as the full agonist, which interacts closely by long-range forces or directly. The compounds showing the higher affinity at both the 5-HT transporter (K(i) < 50 nM) and the 5-HT(1A) receptors (K(i) < 20 nM) were further explored for their ability to stimulate [(35)S]GTPgammaS binding or to antagonize 8-hydroxy-2-di-n-propylamino-tetralin (8-OH-DPAT)-stimulated [(35)]GTPgammaS binding to rat hippocampal membranes, an index of agonist/antagonist action at 5-HT(1A) receptors, respectively. Compound 8g exhibited agonist activity (EC(50) = 30 nM) in this assay, whereas compounds 7g and 8h,i behaved as weak partial agonists and 7h-j and 8j,l antagonized the R(+)-8-OH

  16. In vivo binding of /sup 125/I-LSD to serotonin 5-HT/sub 2/ receptors in mouse brain

    SciTech Connect

    Hartig, P.R.; Scheffel, U., Frost, J.J.; Wagner, H.N. Jr.

    1985-08-19

    The binding of /sup 125/I-LSD (2-(/sup 125/I)-lysergic acid diethylamide) was studied in various mouse brain regions following intravenous injection of the radioligand. The high specific activity of /sup 125/I-LSD enabled the injection of low mass doses (14ng/kg), which are well below the threshold for induction of any known physiological effect of the probe. The highest levels of /sup 125/I-LSD binding were found in the frontal cortex, olfactory tubercles, extra-frontal cortex and striatum while the lowest level was found in the cerebellum. Binding was saturable in the frontal cortex but increased linearly in the cerebellum with increasing doses of /sup 125/I-LSD. Serotonergic compounds potently inhibited /sup 125/I-LSD binding in cortical regions, olfactory tubercles, and hypothalamus but had no effect in the cerebellum. Dopaminergic compounds caused partial inhibition of binding in the striatum while adrenergic compounds were inactive. From these studies the authors conclude that /sup 125/I-LSD labels serotonin 5-HT/sub 2/ receptor sites in cortical regions with no indication that other receptor sites are labeled. In the olfactory tubercles and hypothalamus, /sup 125/I-LSD labeling occurs predominantly or entirely at serotonic 5-HT/sub 2/ sites. In the striatum, /sup 125/I-LSD labels approximately equal proportions of serotonergic and dopaminergic sites. These data indicate that /sup 125/I-LSD labels serotonin receptors in vivo and suggests that appropriate derivatives of 2I-LSD may prove useful for tomographic imaging of serotonin 5-HT/sub 2/ receptors in the mammalian cortex.

  17. 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.

  18. Pharmacokinetic–pharmacodynamic modelling of fluvoxamine 5-HT transporter occupancy in rat frontal cortex

    PubMed Central

    Geldof, M; Freijer, J I; van Beijsterveldt, L; Langlois, X; Danhof, M

    2008-01-01

    Background and purpose: The pharmacokinetic–pharmacodynamic (PK–PD) correlation of fluvoxamine 5-HT transporter (SERT) occupancy was determined in rat frontal cortex ex vivo. Experimental approach: Rats (n=47) with permanent arterial and venous cannulas received a 30 min intravenous infusion of fluvoxamine (1 or 7.3 mg kg−1). At various time points after dosing, brains were collected for determination of fluvoxamine concentration and SERT occupancy. In addition, the time course of fluvoxamine concentration in plasma was determined up to the time of brain collection. In a separate study (n=26), the time course of fluvoxamine concentration in brain extracellular fluid (ECF) and plasma was determined. The results of the investigations were interpreted by nonlinear mixed effects modeling Key results: Highest SERT occupancy was reached at the first time point (10 or 15 min) and maintained for 1.5 and 7 h after 1 and 7.3 mg kg−1, respectively. Thereafter, SERT occupancy decreased linearly at a rate of 8% h−1. SERT occupancy could be directly related to plasma, brain ECF and brain tissue concentrations by a hyperbolic function (Bmax model). Maximal SERT occupancy (Bmax) was 95%. Estimated concentrations at half-maximal SERT occupancy (EC50) in plasma, ECF and brain tissue were 0.48, 0.22 and 14.8 ng mL−1 respectively. The minimum value of the objective function decreased 12 points for ECF and brain tissue concentrations relative to plasma (P<0.01), presumably as a result of nonlinear brain distribution. Conclusions and implications: The proposed PK–PD model constitutes a useful basis for prediction of the time course of ex vivo SERT occupancy in behavioural studies with selective serotonin reuptake inhibitors. PMID:18493251

  19. Correlated gene expression encoding serotonin (5-HT) receptor 4 and 5-HT transporter in proximal colonic segments of mice across different colonization states and sexes.

    PubMed

    Reigstad, C S; Linden, D R; Szurszewski, J H; Sonnenburg, J L; Farrugia, G; Kashyap, P C

    2016-09-01

    The production and handling of serotonin (5-HT) is an important determinant of colonic motility and has been reported to be altered in gastrointestinal (GI) disorders such as irritable bowel syndrome (IBS). Recent studies suggest that the intestinal microbiota and sex of the host can influence expression of genes involved in 5-HT biosynthesis and signaling. While expression of genes in serotonergic pathways has been shown to be variable, it remains unclear whether genes within this pathway are coregulated. As a first step in that direction, we investigated potential correlations in relative mRNA expression of serotonergic genes, in the proximal colon isolated from male and female mice in different states of microbial association: germ-free (GF), humanized (ex-germ-free colonized with human gut microbiota, HM), and conventionally raised (CR) mice. Among the 10 pairwise comparisons conducted between five serotonergic transcripts, Tph1, Chga, Maoa, Slc6a4, and Htr4, we found a strong, positive correlation between colonic expression of Slc6a4 and Htr4 across different colonization states and sexes. We also identified a positive correlation between the expression of Tph1 and Chga; however, there were no correlations observed between any other tested pair of 5-HT-related transcripts. These data suggest that correlated expression of Slc6a4 and Htr4 likely involves coregulation of genes located on different chromosomes which modulate serotonergic activity in the gut. Further work will need to be done to understand the pathways and cell types responsible for this correlated expression, given the important role of 5-HT in gastrointestinal physiology.

  20. Development of 5-HT transporter density and long-term effects of methylphenidate in an animal model of ADHD.

    PubMed

    Roessner, Veit; Manzke, Till; Becker, Andreas; Rothenberger, Aribert; Bock, Nathalie

    2009-01-01

    Although stimulants as the treatment of choice are widely prescribed in ADHD, little is known about their long-term neurobiological effects. Hence, for the first time the present study examined the long-term effects of chronic methylphenidate (MPH) administration on striatal 5-hydroxytryptamine transporter (5-HTT) densities in an animal model of ADHD. First, it compared the normal development of striatal 5-HTT densities of spontaneously hypertensive rats (SHR) as an animal model of ADHD and Wistar Kyoto (WKY) rats as controls; binding of the highly selective ligand of 5-HTT [(3)H]paroxetine was determined on membrane preparations of the striatum of SHR and WKY rats on postnatal days 25, 50, and 90, i.e. from the time of weaning until adulthood. Second, the long-term effect of chronic administration of 2 mg/kg per day MPH at two different developmental stages (days 25-39 or 50-64) on the striatal 5-HTT density was examined in both rat strains at day 90. Long-term effects of MPH treatment on striatal 5-HTT density in adulthood could be ruled out in both healthy (WKY) and "ADHD" rats (SHR). But a higher striatal 5-HTT density in older SHR versus WKY rats might indicate ADHD specific changes in the 5-HT system that needs further investigation not only in animals.

  1. Cloned human 5-HT1A receptor pharmacology determined using agonist binding and measurement of cAMP accumulation.

    PubMed

    Sharif, Najam A; Drace, Colene D; Williams, Gary W; Crider, Julie Y

    2004-10-01

    Twenty agonists and nine antagonists were evaluated for their ability to compete for [3H]-8-hydroxy-2-(di-n-propylamino)tetralin ([3H]-8-OH-DPAT) binding to the cloned human serotonin-1A (ch-5-HT1A) receptor expressed in Chinese hamster ovary cells and for their ability to alter adenylyl cyclase activity in the same cells. The most potent full agonists of high affinity included N,N-dipropyl-5-carboxamidotryptamine (pEC50=9.6 +/- 0.1), MDL 73005EF (pEC50=9.3 +/- 0.2), 5-methyl-urapidil (pEC50=9.2 +/- 0.1), 5-carboxamidotryptamine (pEC50=9.1 +/- 0.2), R(+)-8-OH-DPAT (pEC50=8.6 +/- 0.1) and BMY-7378 (pEC50=8.6 +/- 0.1). WB-4101 (pEC50=8.3 +/- 0.2; IA=79%), clozapine (pEC50=8.1 +/- 0.3; IA=29%), (buspirone (pEC50=7.6 +/- 0.2; IA=79%), quipazine (pEC50 <5; IA=45%) and R-DOI (pEC50 < 5; IA=31%) were weaker agonists with partial agonist properties. The most potent antagonists were WAY-100,635 (pKi=10.2 +/- 0.1), methiothepin (pKi=8.8 +/- 0.2), spiperone (pKi=8.7 +/- 0.2) and NAN-190 (pKi=8.5 +/- 0.2). The receptor affinities and functional potencies were well correlated (r=0.88; P <0.0001). Our binding data correlated well with the pharmacology of endogenous 5-HT1A receptors in the rabbit iris-ciliary body (r=0.91; P <0.001) and rat hippocampus (r=0.93, P <0.0001). Our functional cAMP data correlated well with other cAMP accumulation data (r=0.8, P <0.01 vs calf hippocampus) but less so with [35S]-GTPgammaS binding to the ch-5-HT(1A) receptor as a functional activity read-out (r=0.58, P <0.05). The present study provides a detailed pharmacological characterization of the ch-5-HT1A receptor using binding and functional assays.

  2. Changes in characteristics of the specific binding of [3H]LY-278584, a 5-HT3-receptor antagonist, on differentiated NG108-15 cells.

    PubMed

    Matsushima, Kayoko; Imanishi, Takashi; Asano, Hajime; Funakami, Yoshinori; Wada, Tetsuyuki; Ichida, Seiji

    2010-01-01

    We have reported previously that the concentration of intracellular Ca2+ evoked by serotonin (5-HT) was significantly augmented in differentiated NG108-15 (NG) cells treated with dibutyryl cAMP and the enhanced response occurred via 5-HT3 receptors. We investigated changes in the characteristics for specific binding of [(3)H]LY-278584 (a specific antagonist of the 5-HT3 receptor) on membranes from differentiated NG cells. The results indicated that the K(d) and B(max) values for the specific binding to differentiated NG cells were significantly smaller and larger, respectively, than those for undifferentiated NG cells. The binding was significantly inhibited by 10 nM tropisetron, a specific 5-HT3-receptor antagonist, but not by any other types of 5-HT-receptor antagonists. These results suggested that the enhanced response by 5-HT in differentiated NG cells was due to both qualitative and quantitative changes in the 5-HT3 receptor.

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

    PubMed Central

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

    2013-01-01

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

  4. Decreased agonist, but not antagonist, binding to the naturally occurring Thr92Lys variant of the h5-HT7(a) receptor.

    PubMed

    Brüss, Michael; Kiel, Sibylle; Bönisch, Heinz; Kostanian, Arevat; Göthert, Manfred

    2005-08-01

    In the present study on transfected human embryonic kidney (HEK)293 cells, we aimed at establishing whether expression of the naturally occurring Thr92Lys variation of the Gs-coupled h5-HT7(a) receptor leads to changes of ligand binding properties, of agonist-evoked cAMP formation and/or of antagonist-mediated blockade of the latter. Binding of [3H]5-carboxamidotryptamine ([3H]5-CT) to membranes and stimulated [3H]cAMP accumulation in whole cells were determined. Saturation binding experiments in membranes of transiently transfected cells expressing either the wild-type or the variant receptor revealed a single binding site in both cases and no difference in Bmax between both receptor isoforms. In competition binding experiments in membranes of stably transfected cells, the Thr92Lys variant exhibited a 2.8-11 times lower binding affinity of the ligands 5-hydroxytryptamine (5-HT), 5-CT, 5-methoxy-3-(1,2,3,6-tetrahydropyridin-4yl)-1H-indole (RU24969), (+/-)-hydroxy-2-(di-n-propylamino)tetralin hydrobromide (8-OH-DPAT) and sumatriptan compared to the wild-type receptor. However, the variant did not differ from the wild-type with respect to the binding properties of the antagonists (R)-3-(2-(2-(4-methylpiperidin-1-yl)ethyl)-pyrrolodine-1-sulfonyl)phenol hydrochloride (SB-269970), risperidone, mesulergine and clozapine. In agreement with the decreased binding affinity of 5-HT, 5-CT, RU24969 and 8-OH-DPAT for the variant receptor, these agonists were less potent in stimulating [3H]cAMP accumulation in cells stably expressing the Thr92Lys h5-HT7(a) receptor. Sumatriptan did not stimulate cAMP accumulation in spite of its affinity for both receptor isoforms pointing to a putative weak antagonistic property of this drug at the h5-HT7 receptor. SB-269970 and clozapine were equipotent at both the variant and the wild-type receptor in producing a rightward shift of the 5-HT concentration-response curve for its stimulant effect on [3H]cAMP accumulation. In view of, e.g., the

  5. Localization of serotoni (5-hydroxytryptamine, 5-HT) with partial purification and characterization of a serotonin binding protein in the intestinal tissue of the nematode Ascaris suum

    SciTech Connect

    Martin, R.E.

    1989-01-01

    An intracellular 5-HT binding protein (SBP) from intestinal tissue was partially purified and characterized. Binding of ({sup 3}H) 5-HT to the protein appeared to be Fe{sup +2}-sensitive and maximal (20.8pmol/mg protein) at 5 {times} 10{sup {minus}4}M Fe{sup +2} and 10{sup {minus}7}M ({sup 3}H) 5-HT. There were two 5-HT binding sites present at optimum Fe{sup +2} concentrations. The Bmax values of these sites were more sensitive to Fe{sup +2} than Kd values. Sulfhydryl reducing agents, cation chelators, Fe{sup +3}, Ca{sup +2} and antagonists of 5-HT uptake and storage inhibited binding of 5-HT to SBP. Gel exclusion chromatography indicated the presence of a 45Kda SBP that in 5 {times} 10{sup {minus}5}M Fe{sup +2} may form aggregates ranging in size from approximately 80 to >1000Kda. The data indicate these in vitro aggregates may correspond to the electron-opaque patches observed in situ. Ascaris suum may provide a model system to further elucidate the physiological role of analogous serotonin binding proteins that have been identified in mammalian systems.

  6. 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.

  7. Spatial orientation of the antagonist granisetron in the ligand-binding site of the 5-HT3 receptor.

    PubMed

    Yan, Dong; White, Michael M

    2005-08-01

    The serotonin type 3 receptor (5-HT(3)R) is a member of the cys-loop ligand-gated ion channel (LGIC) superfamily. Like almost all membrane proteins, high-resolution structural data are unavailable for this class of receptors. We have taken advantage of the high degree of homology between LGICs and the acetylcholine binding protein (AChBP) from the freshwater snail Lymnea stagnalis, for which high-resolution structural data are available, to create a structural model for the extracellular (i.e., ligand-binding) domain of the 5-HT(3)R and to perform a series of ligand docking experiments to delineate the architecture of the ligand-binding site. Structural models were created using homology modeling with the AChBP as a template. Docking of the antagonist granisetron was carried out using a Lamarckian genetic algorithm to produce models of ligand-receptor complexes. Two energetically similar conformations of granisetron in the binding site were obtained from the docking simulations. In one model, the indazole ring of granisetron is near Trp90 and the tropane ring is near Arg92; in the other, the orientation is reversed. We used double-mutant cycle analysis to determine which of the two orientations is consistent with experimental data and found that the data are consistent with the model in which the indazole ring of granisetron interacts with Arg92 and the tropane ring interacts with Trp90. The combination of molecular modeling with double-mutant cycle analysis offers a powerful approach for the delineation of the architecture of the ligand-binding site.

  8. 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.

  9. Autoradiographic Mapping of 5-HT(1B/1D) Binding Sites in the Rhesus Monkey Brain Using [carbonyl-C]zolmitriptan.

    PubMed

    Lindhe, Orjan; Almqvist, Per; Kågedal, Matts; Gustafsson, Sven-Åke; Bergström, Mats; Nilsson, Dag; Antoni, Gunnar

    2011-01-01

    Zolmitriptan is a serotonin 5-HT(1B/1D) receptor agonist that is an effective and well-tolerated drug for migraine treatment. In a human positron emission tomography study, [(11)C]zolmitriptan crossed the blood-brain barrier but no clear pattern of regional uptake was discernable. The objective of this study was to map the binding of [(11)C]zolmitriptan in Rhesus monkey brain using whole hemisphere in vitro autoradiography with [(11)C]zolmitriptan as a radioligand. In saturation studies, [(11)C]zolmitriptan showed specific (90%) binding to a population of high-affinity binding sites (Kd 0.95-5.06 nM). There was regional distribution of binding sites with the highest density in the ventral pallidum, followed by the external globus pallidus, substantia nigra, visual cortex, and nucleus accumbens. In competitive binding studies with 5-HT(1) receptor antagonists, [(11)C]zolmitriptan binding was blocked by selective 5-HT(1B) and 5-HT(1D) ligands in all target areas. There was no appreciable change in binding with the addition of a 5-HT(1A) receptor antagonist.

  10. 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.

  11. 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

  12. Cardiovascular afferents cause the release of 5-HT in the nucleus tractus solitarii; this release is regulated by the low- (PMAT) not the high-affinity transporter (SERT)

    PubMed Central

    Hosford, Patrick S; Millar, Julian; Ramage, Andrew G

    2015-01-01

    Key points The nucleus tractus solitarii (NTS) integrates visceral afferent information essential for cardiovascular haemostasis. Using fast-cyclic voltammetry in anaesthetized rats, 5-HT (serotonin) release was detected in NTS in response to activation of these afferents. Removal of 5-HT from the extracellular space is usually regulated by the low-capacity, high-affinity 5-HT transporter (5-HTT/SERT). The present data demonstrate that 5-HT removal in the NTS is regulated by the plasma membrane monoamine transporter (PMAT), a high-capacity, low-affinity transporter. The present data also demonstrate that the 5-HT released by afferent activation comes from at least two different sources. It is suggested that one of these sources is the afferents themselves. These results demonstrate a physiological role for the low-affinity uptake transporter in the regulation of 5-HT concentration in NTS. Abstract The nucleus tractus solitarii (NTS) integrates inputs from cardiovascular afferents and thus is crucial for cardiovascular homeostasis. These afferents primarily release glutamate, although 5-HT has also been shown to play a role in their actions. Using fast-cyclic voltammetry, an increase in 5-HT concentrations (range 12–50 nm) could be detected in the NTS in anaesthetized rats in response to electrical stimulation of the vagus and activation of cardiopulmonary, chemo- and baroreceptor reflexes. This 5-HT signal was not potentiated by the serotonin transporter (SERT) or the noradrenaline transporter (NET) inhibitors citalopram and desipramine (1 mg kg−1). However, decynium-22 (600 μg kg−1), an organic cation 3 transporter (OCT3)/plasma membrane monoamine transporter (PMAT) inhibitor, increased the 5-HT signal by 111 ± 21% from 29 ± 10 nm. The effectiveness of these inhibitors was tested against the removal time of 5-HT and noradrenaline applied by microinjection to the NTS. Citalopram and decynium-22 attenuated the removal of 5-HT but not

  13. Identification of residues in transmembrane regions III and VI that contribute to the ligand binding site of the serotonin 5-HT6 receptor.

    PubMed

    Boess, F G; Monsma, F J; Sleight, A J

    1998-11-01

    We have examined the ligand binding site of the serotonin 5-HT6 receptor using site-directed mutagenesis. Replacing the highly conserved Asp106 in transmembrane region III by asparagine eliminated D-[3H]-lysergic acid diethylamide ([3H]LSD) binding to the mutant receptor transiently expressed in HEK293 cells. The potency of 5-HT and LSD to stimulate adenylyl cyclase was reduced by 3,600- and 500-fold, respectively, suggesting that an ionic interaction between the positively charged amino group of 5-HT and D106 is essential for high-affinity binding and important for receptor activation. In addition, basal cyclic AMP levels in cells expressing this mutant were increased. Mutation of a tryptophan residue one helix turn toward the extracellular side of transmembrane region III (Trp102) to phenylalanine produced significant changes in the binding affinity and potency of several ligands, consistent with a role of this residue in the formation of the ligand binding site. The exchange of two neighboring residues in the carboxy-terminal half of transmembrane region VI (Ala287 and Asn288) for leucine and serine resulted in a mutant receptor with increased affinities (seven- to 30-fold) for sumatriptan and several ergopeptine ligands. The identification of these interactions will help to improve models of the 5-HT6 receptor ligand binding site.

  14. Identification of essential residues for binding and activation in the human 5-HT7(a) serotonin receptor by molecular modeling and site-directed mutagenesis

    PubMed Central

    Impellizzeri, Agata Antonina Rita; Pappalardo, Matteo; Basile, Livia; Manfra, Ornella; Andressen, Kjetil Wessel; Krobert, Kurt Allen; Messina, Angela; Levy, Finn Olav; Guccione, Salvatore

    2015-01-01

    The human 5-HT7 receptor is expressed in both the central nervous system and peripheral tissues and is a potential drug target in behavioral and psychiatric disorders. We examined molecular determinants of ligand binding and G protein activation by the human 5-HT7(a) receptor. The role of several key residues in the 7th transmembrane domain (TMD) and helix 8 were elucidated combining in silico and experimental mutagenesis. Several single and two double point mutations of the 5-HT7(a) wild type receptor were made (W7.33V, E7.35T, E7.35R, E7.35D, E7.35A, R7.36V, Y7.43A, Y7.43F, Y7.43T, R8.52D, D8.53K; E7.35T-R7.36V, R8.52D-D8.53K), and their effects upon ligand binding were assessed by radioligand binding using a potent agonist (5-CT) and a potent antagonist (SB269970). In addition, the ability of the mutated 5-HT7(a) receptors to activate G protein after 5-HT-stimulation was determined through activation of adenylyl cyclase. In silico investigation on mutated receptors substantiated the predicted importance of TM7 and showed critical roles of residues E7.35, W7.33, R7.36 and Y7.43 in agonist and antagonist binding and conformational changes of receptor structure affecting adenylyl cyclase activation. Experimental data showed that mutants E7.35T and E7.35R were incapable of ligand binding and adenylyl cyclase activation, consistent with a requirement for a negatively charged residue at this position. The mutant R8.52D was unable to activate adenylyl cyclase, despite unaffected ligand binding, consistent with the R8.52 residue playing an important role in the receptor-G protein interface. The mutants Y7.43A and Y7.43T displayed reduced agonist binding and AC agonist potency, not seen in Y7.43F, consistent with a requirement for an aromatic residue at this position. Knowledge of the molecular interactions important in h5-HT7 receptor ligand binding and G protein activation will aid the design of selective h5-HT7 receptor ligands for potential pharmacological use. PMID

  15. Identification of essential residues for binding and activation in the human 5-HT7(a) serotonin receptor by molecular modeling and site-directed mutagenesis.

    PubMed

    Impellizzeri, Agata Antonina Rita; Pappalardo, Matteo; Basile, Livia; Manfra, Ornella; Andressen, Kjetil Wessel; Krobert, Kurt Allen; Messina, Angela; Levy, Finn Olav; Guccione, Salvatore

    2015-01-01

    The human 5-HT7 receptor is expressed in both the central nervous system and peripheral tissues and is a potential drug target in behavioral and psychiatric disorders. We examined molecular determinants of ligand binding and G protein activation by the human 5-HT7(a) receptor. The role of several key residues in the 7th transmembrane domain (TMD) and helix 8 were elucidated combining in silico and experimental mutagenesis. Several single and two double point mutations of the 5-HT7(a) wild type receptor were made (W7.33V, E7.35T, E7.35R, E7.35D, E7.35A, R7.36V, Y7.43A, Y7.43F, Y7.43T, R8.52D, D8.53K; E7.35T-R7.36V, R8.52D-D8.53K), and their effects upon ligand binding were assessed by radioligand binding using a potent agonist (5-CT) and a potent antagonist (SB269970). In addition, the ability of the mutated 5-HT7(a) receptors to activate G protein after 5-HT-stimulation was determined through activation of adenylyl cyclase. In silico investigation on mutated receptors substantiated the predicted importance of TM7 and showed critical roles of residues E7.35, W7.33, R7.36 and Y7.43 in agonist and antagonist binding and conformational changes of receptor structure affecting adenylyl cyclase activation. Experimental data showed that mutants E7.35T and E7.35R were incapable of ligand binding and adenylyl cyclase activation, consistent with a requirement for a negatively charged residue at this position. The mutant R8.52D was unable to activate adenylyl cyclase, despite unaffected ligand binding, consistent with the R8.52 residue playing an important role in the receptor-G protein interface. The mutants Y7.43A and Y7.43T displayed reduced agonist binding and AC agonist potency, not seen in Y7.43F, consistent with a requirement for an aromatic residue at this position. Knowledge of the molecular interactions important in h5-HT7 receptor ligand binding and G protein activation will aid the design of selective h5-HT7 receptor ligands for potential pharmacological use.

  16. 5-HT(1A) receptor and 5-HTT binding during the menstrual cycle in healthy women examined with [(11)C] WAY100635 and [(11)C] MADAM PET.

    PubMed

    Jovanovic, Hristina; Karlsson, Per; Cerin, Asta; Halldin, Christer; Nordström, Anna-Lena

    2009-04-30

    The aim of the present study was to explore the effects of the menstrual cycle phases on 5-HT(1A) receptor and 5-HTT binding potentials (BPs) in healthy women by using positron emission tomography (PET). Women were investigated in the follicular and luteal phase of the menstrual cycle with radioligands [(11)C]WAY10035 (n=13) and [(11)C]MADAM (n=8) to study 5-HT(1A) and 5-HTT BPs. The BPs values were quantified using the simplified reference tissue model. The phases of the menstrual cycle were characterized by transvaginal ultrasound (TSV) and plasma levels of hormones estradiol (E(2)), progesterone (P(4)), follicle stimulating hormone (FSH) and luteinizing hormone (LH).The 5-HT(1A) receptor and 5-HTT BPs did not significantly differ between follicular and luteal phases in any of the investigated regions. There were no significant correlations between the change in E(2) or P(4) values with the change in 5-HT(1A) receptor or 5-HTT BPs. The results provide principally a new in vivo finding in human female biology, suggesting the absence of influence of menstrual cycle phase on 5-HT(1A) receptors or 5-HTT. The finding however does not preclude that gonadal hormones differentially influence central serotonin system inwomen and men, which might contribute to gender differences in serotonin-associated disorders.

  17. The influences of reserpine and imipramine on the 5-HT2 receptor binding site and its coupled second messenger in rat cerebral cortex.

    PubMed

    Lee, Ming-Jen; Wei, Jiann-Wu

    2013-08-31

    An investigation on the molecular mechanism of depression state, less attention was focused on changes at the intracellular messenger level. In this study the effects of reserpine, a monoamine depletor, and imipramine, an antidepressant, on serotonin-2 (5-HT2) receptor binding and its second messenger system of rat cerebral cortex were studied. The level of inositol 4-monophosphate (IP1) accumulation elicited by 100 microM 5-HT via activation of the 5-HT2 receptor on cerebral cortical slices at twelve hours after a single dose of reserpine (2 mg/kg, i.p.) was significantly higher in treated rats, when compared to that of saline-treated rats; this significant level lasted for at least four days. The level of IP1 accumulation in rat cerebral cortical slices elicited by 100 microM serotonin was higher in the group pretreated with reserpine (0.25 mg/kg/day) sub-chronically for seven days than the group pretreated with normal saline. In the receptor binding study, the maximum binding (B(max)) of 5-HT2 receptor binding was increased, when compared to the corresponding controls; whereas, the dissociation equilibrium constant (K(d)) value of the 5-HT2 receptor was found unchanged in the reserpine treated group. Increases in the sensitivity of phosphoinositol (PI) turnover coupled with the 5-HT2 receptor were also found in the long-term (21 days) low dose (0.1 mg/kg/day) administration of reserpine. However, a long-term administration of imipramine (10 mg/kg/day) reduced the function of the PI turnover coupled with the 5-HT2 receptor. Results obtained from the combined use of reserpine and imipramine demonstrated that this combination was able to antagonize the super-sensitivity of the second messenger responses in 5-HT2 receptor induced by long-term treatment with reserpine. Long-term treatment with reserpine but not imipramine also caused an increase in the B(max) of the 5-HT2 receptor. This up-regulation of the 5-HT2 receptor by reserpine could be antagonized by

  18. Exploration of the ligand binding site of the human 5-HT(4) receptor by site-directed mutagenesis and molecular modeling.

    PubMed

    Mialet, J; Dahmoune, Y; Lezoualc'h, F; Berque-Bestel, I; Eftekhari, P; Hoebeke, J; Sicsic, S; Langlois, M; Fischmeister, R

    2000-06-01

    Among the five human 5-HT(4) (h5-HT(4)) receptor isoforms, the h5-HT(4(a)) receptor was studied with a particular emphasis on the molecular interactions involved in ligand binding. For this purpose, we used site-directed mutagenesis of the transmembrane domain. Twelve mutants were constructed with a special focus on the residue P4.53 of helix IV which substitutes in h5-HT(4) receptors the highly conserved S residue among the rhodopsin family receptors. The mutated receptors were transiently expressed in COS-7 cells. Ligand binding or competition studies with two h5-HT(4) receptor agonists, serotonin and ML10302 and two h5-HT(4) receptor antagonists, [(3)H]-GR113808 and ML10375 were performed on wild type and mutant receptors. Functional activity of the receptors was evaluated by measuring the ability of serotonin to stimulate adenylyl cyclase. Ligand binding experiments revealed that [(3)H]-GR113808 did not bind to mutants P4.53A, S5.43A, F6.51A, Y7.43A and to double mutant F6.52V/N6.55L. On the other hand mutations D3.32N, S5.43A and Y7.43A appeared to promote a dramatic decrease of h5-HT(4(a)) receptor functional activity. From these studies, S5.43 and Y7.43 clearly emerged as common anchoring sites to antagonist [(3)H]-GR113808 and to serotonin. According to these results, we propose ligand-receptor complex models with serotonin and [(3)H]-GR113808. For serotonin, three interaction points were selected including ionic interaction with D3.32, a stabilizing interaction of this ion pair by Y7.43 and a hydrogen bond with S5.43. [(3)H]-GR113808 was also docked, based on the same type of interactions with S5.43 and D3.32: the proposed model suggested a possible role of P4.53 in helix IV structure allowing the involvement of a close hydrophobic residue, W4.50, in a hydrophobic pocket for hydrophobic interactions with the indole ring of [(3)H]-GR113808.

  19. Cation-pi interactions in ligand recognition by serotonergic (5-HT3A) and nicotinic acetylcholine receptors: the anomalous binding properties of nicotine.

    PubMed

    Beene, Darren L; Brandt, Gabriel S; Zhong, Wenge; Zacharias, Niki M; Lester, Henry A; Dougherty, Dennis A

    2002-08-13

    A series of tryptophan analogues has been introduced into the binding site regions of two ion channels, the ligand-gated nicotinic acetylcholine and serotonin 5-HT(3A) receptors, using unnatural amino acid mutagenesis and heterologous expression in Xenopus oocytes. A cation-pi interaction between serotonin and Trp183 of the serotonin channel 5-HT(3A)R is identified for the first time, precisely locating the ligand-binding site of this receptor. The energetic contribution of the observed cation-pi interaction between a tryptophan and the primary ammonium ion of serotonin is estimated to be approximately 4 kcal/mol, while the comparable interaction with the quaternary ammonium of acetylcholine is approximately 2 kcal/mol. The binding mode of nicotine to the nicotinic receptor of mouse muscle is examined by the same technique and found to differ significantly from that of the natural agonist, acetylcholine.

  20. 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.

  1. 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.

  2. Hydrogen peroxide (H/sub 2/O/sub 2/) stimulates the active transport of 5-hydroxytryptamine (5-HT) into platelets

    SciTech Connect

    Bosin, T.R.

    1986-03-01

    Platelets function in a variety of physiological and pathological processes which may be altered by oxidant injury. One such process is the active transport 5-HT, which is an important mechanism in the control of circulating 5-HT levels. Exposure of mouse platelets (10/sup 8//ml) to H/sub 2/O/sub 2/ caused a time-dependent and dose-dependent increase in 5-HT (10/sup -7/M) uptake. The uptake 4 and 10 min following H/sub 2/O/sub 2/ (50 ..mu..M) was 228% and 145% of control values, respectively. Fluoxetine (10/sup -6/M) blocked all 5-HT uptake and catalase (1500 U/ml) blocked the H/sub 2/O/sub 2/-stimulated uptake. Enzymatically produced H/sub 2/O/sub 2/ (glucose/glucose oxidase) and xanthine (X)/xanthine oxidase (XO) generated oxygen radicals produced quantitatively and qualitatively similar results. The stimulatory response of platelets to X/XO generated oxidants was unaffected by superoxide dismutase (250 U/ml) but, was inhibited using heat-denatured XO, allopurinol (0.5 mM) and catalase; fluoxetine inhibited all 5-HT uptake. Platelets exposed to X/XO in the presence of chelated (EDTA, 100 ..mu..M) or unchelated FeSO/sub 4/, FeNH/sub 4/(SO/sub 4/)/sub 2/ or CuCl (50 ..mu..M) did not have altered 5-HT uptake. These data indicate that brief exposure of platelets to physiological levels of H/sub 2/O/sub 2/ results in marked, reversible stimulation of active 5-HT uptake which may represent a homeostatic defense mechanism when H/sub 2/O/sub 2/ is elevated in the platelet microenvironment.

  3. Serotonin transporter, 5-HT1A receptor, and behavior in DBA/2J mice in comparison with four inbred mouse strains.

    PubMed

    Popova, Nina K; Naumenko, Vladimir S; Tibeikina, Marina A; Kulikov, Alexander V

    2009-12-01

    Prepulse inhibition (PPI), the reduction in acoustic startle produced when it is preceded by a weak prepulse stimulus, is impaired in schizophrenic patients. The DBA/2J mouse strain displayed deficient PPI and is therefore suggested as an experimental animal model for the loss of sensorimotor gating in schizophrenia. Brain serotonin (5-HT) has been implicated in the pathophysiology of several psychiatric disorders, including major depressive disorder and schizophrenia. In the present study, behavior, 5-HT transporter (5-HTT) mRNA level, 5-HT(1A) receptor mRNA level, and 5-HT(1A) receptor density in the brain regions were studied in DBA/2J mice in comparison with four inbred mouse strains (CBA/Lac, C57BL/6, BALB/c, and ICR). A decrease in 5-HTT mRNA level in the midbrain and a reduced density of 5-HT(1A) receptors in the frontal cortex without significant changes in 5-HT(1A) receptor mRNA level in DBA/2J mice were found. It was shown that, along with decreased PPI, DBA/2J mice demonstrated considerably reduced immobility in the tail suspension test and in the forced swim test. No significant interstrain differences in intermale aggression, or in light-dark box and elevated plus-maze tests, were found. The results suggested the involvement of decreased 5-HTT gene expression and 5-HT(1A) receptor density in genetically defined PPI deficiency and showed a lack of any association between PPI deficiency and predisposition to aggressive, anxiety, and depressive-like behaviors.

  4. 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.

  5. Cerebral metabolic responses to 5-HT2A/C receptor activation in mice with genetically modified serotonin transporter (SERT) expression.

    PubMed

    Dawson, Neil; Ferrington, Linda; Lesch, Klaus-Peter; Kelly, Paul A T

    2011-01-01

    Variation in the human serotonin transporter gene (hSERT; 5-HTT) resulting in a life-long alteration in SERT function influences anxiety and the risk of developing affective disorders. The mechanisms underlying the influence of the hSERT gene on these phenotypes remain unclear but may involve altered 5-HT receptor function. Here we characterise the cerebral metabolic response to 5-HT(2A/C) receptor activation in two transgenic mouse models of altered SERT function, SERT knock-out (SERT KO) and hSERT over-expressing (hSERT OE) mice, to test the hypothesis that genetically mediated variability in SERT expression alters 5-HT(2A/C) function. We found that a constitutive increase in SERT expression (hSERT OE) enhanced, whereas a constitutive decrease in SERT expression (SERT KO) attenuated, 5-HT(2A/C) function. Therefore, altered 5-HT(2A/C) receptor functioning in response to hSERT gene variation may contribute to its influence on affective phenotypes.

  6. Interaction between serotonin 5-HT2A receptor gene and dopamine transporter (DAT1) gene polymorphisms influences personality trait of persistence in Austrian Caucasians.

    PubMed

    Schosser, Alexandra; Fuchs, Karoline; Scharl, Theresa; Schloegelhofer, Monika; Kindler, Jochen; Mossaheb, Nilufar; Kaufmann, Rainer M; Leisch, Friedrich; Kasper, Siegfried; Sieghart, Werner; Aschauer, Harald N

    2010-03-01

    We examined 89 normal volunteers using Cloninger's Temperament and Character Inventory (TCI). Genotyping the 102T/C polymorphism of the serotonin 5HT2A receptor gene and the ser9gly polymorphism in exon 1 of the dopamine D3 receptor (DRD3) gene was performed using PCR-RFLP, whereas the dopamine transporter (DAT1) gene variable number of tandem repeats (VNTR) polymorphism was investigated using PCR amplification followed by electrophoresis in an 8% acrylamide gel with a set of size markers. We found a nominally significant association between gender and harm avoidance (P=0.017; women showing higher scores). There was no association of either DAT1, DRD3 or 5HT2A alleles or genotypes with any dimension of the TCI applying Kruskal-Wallis rank-sum tests. Comparing homozygote and heterozygote DAT1 genotypes, we found higher novelty seeking scores in homozygotes (P=0.054). We further found a nominally significant interaction between DAT1 and 5HT2A homo-/heterozygous gene variants (P=0.0071; DAT1 and 5HT2A genotypes P value of 0.05), performing multivariate analysis of variance (MANOVA). Examining the temperamental TCI subscales, this interaction was associated with persistence (genotypes: P=0.004; homo-/heterozygous gene variants: P=0.0004). We conclude that an interaction between DAT1 and 5HT2A genes might influence the temperamental personality trait persistence.

  7. Centrally acting hypotensive agents with affinity for 5-HT1A binding sites inhibit forskolin-stimulated adenylate cyclase activity in calf hippocampus.

    PubMed Central

    Schoeffter, P.; Hoyer, D.

    1988-01-01

    1. A number of centrally acting hypotensive agents and other ligands with high affinity for 5-hydroxytryptamine1A (5-HT1A) recognition sites have been tested on forskolin-stimulated adenylate cyclase activity in calf hippocampus, a functional model for 5-HT1A-receptors. 2. Concentration-dependent inhibition of forskolin-stimulated adenylate cyclase activity was elicited by the reference 5-HT1-receptor agonists (mean EC50 value, nM): 5-HT (22), 5-carboxamidotryptamine (5-CT, 3.2), 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT, 8.6), N,N-dipropyl-5-carboxamidotryptamine (DP-5-CT, 2.3), 1-[2-(4-aminophenyl)ethyl]-4-(3-trifluoromethylphenyl)-piperazine (PAPP or LY 165163, 20), 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H indole (RU 24969, 20), buspirone (65) and ipsapirone (56). Emax amounted to 18-20% inhibition for all but the latter two agonists (14%). 3. The following hypotensive agents with high affinity for 5-HT1A sites were potent agonists in this system (mean EC50 value, nM): flesinoxan (24), indorenate (99), erythro-1-(1-[2-(1,4-benzodioxan-2-yl)-2-hydroxyethyl]-4-piperidyl )- 2-benzimidazolinone (R 28935, 2.5), urapidil (390) and 5-methyl-urapidil (3.5). The first two agents were full agonists, whereas the latter three acted as partial agonists with 60-80% efficacy. 4. Metergoline and methysergide behaved as full agonists and cyanopindolol as a partial agonist with low efficacy. Spiroxatrine and 2-(2,6-dimethoxyphenoxyethyl)aminomethyl- 1,4-benzodioxane (WB 4101) which bind to 5-HT1A sites with nanomolar affinity, were agonists and inhibited potently forskolin-stimulated adenylate cyclase in calf hippocampus, showing mean EC50 values of 23 and 15 nM, respectively. Spiroxatrine and WB 4101 yielded 90% and 50% efficacy, respectively. 5. Spiperone and methiothepin (each 1 microM) caused rightward shifts of the concentration-effect curve to 8-OH-DPAT, without loss of the maximal effect, as did the partial agonist cyanopindolol (0.1 microM) and the

  8. Influence of sodium substitutes on 5-HT-mediated effects at mouse 5-HT3 receptors

    PubMed Central

    Barann, M; Schmidt, K; Göthert, M; Urban, B W; Bönisch, H

    2004-01-01

    The influence of sodium ion substitutes on the 5-hydroxytryptamine (5-HT)-induced flux of the organic cation [14C]guanidinium through the ion channel of the mouse 5-HT3 receptor and on the competition of 5-HT with the selective 5-HT3 receptor antagonist [3H]GR 65630 was studied, unless stated otherwise, in mouse neuroblastoma N1E-115 cells. Under physiological conditions (135 mM sodium), 5-HT induced a concentration-dependent [14C]guanidinium influx with an EC50 (1.3 μM) similar to that in electrophysiological studies. The stepwise replacement of sodium by increasing concentrations of the organic cation hydroxyethyl trimethylammonium (choline) concentration dependently caused both a rightward shift of the 5-HT concentration–response curve and an increase in the maximum effect of 5-HT. Complete replacement of sodium resulted in a 34-fold lower potency of 5-HT and an almost two times higher maximal response. A low potency of 5-HT in choline buffer was also observed in other 5-HT3 receptor-expressing rodent cell lines (NG 108-15 or NCB 20). Replacement of Na+ by Li+ left the potency and maximal effects of 5-HT almost unchanged. Replacement by tris (hydroxymethyl) methylamine (Tris), tetramethylammonium (TMA) or N-methyl-D-glucamine (NMDG) caused an increase in maximal response to 5-HT similar to that caused by choline. The potency of 5-HT was only slightly reduced by Tris, to a high degree decreased by TMA (comparable to the decrease by choline), but not influenced by NMDG. The potency of 5-HT in inhibiting [3H]GR65630 binding to intact cells was 35-fold lower when sodium was completely replaced by choline, but remained unchanged after replacement by NMDG. The results are compatible with the suggestion that choline competes with 5-HT for the 5-HT3 receptor; the increase in maximal response may be partly due to a choline-mediated delay of the 5-HT-induced desensitization. For studies of 5-HT-evoked [14C]guanidinium flux through 5-HT3 receptor channels, NMDG appears

  9. 5-HT(1A) receptors and memory.

    PubMed

    Meneses, Alfredo; Perez-Garcia, Georgina

    2007-01-01

    The study of 5-hydroxytryptamine (5-HT) systems has benefited from the identification, classification and cloning of multiple 5-HT receptors (5-HT(1)-5-HT(7)). Increasing evidence suggests that 5-HT pathways, reuptake site/transporter complex and 5-HT receptors represent a strategic distribution for learning and memory. A key question still remaining is whether 5-HT markers (e.g., receptors) are directly or indirectly contributing to the physiological and pharmacological basis of memory and its pathogenesis or, rather, if they represent protective or adaptable mechanisms (at least in initial stages). In the current paper, the major aim is to revise recent advances regarding mammalian 5-HT(1A) receptors in light of their physiological, pathophysiological and therapeutic implications in memory. An attempt is made to identify and discuss sources of discrepancies by employing an analytic approach to examine the nature and degree of difficulty of behavioral tasks used, as well as implicating other factors (for example, brain areas, training time or duration, and drug administration) which might offer new insights into the understanding and interpretation of these data. In this context, 8-OH-DPAT deserves special attention since for many years it has been the more selective 5-HT drug and, hence, more frequently used. As 5-HT(1A) receptors are key components of serotonergic signaling, investigation of their memory mechanisms and action sites and the conditions under which they might operate, could yield valuable insights. Moreover, selective drugs with agonists, neutral antagonists or inverse agonist properties for 5-HT(1A) (and 5-HT(7)) receptors may constitute a new therapeutic opportunity for learning and memory disorders.

  10. Higher Pre-treatment 5-HT1A Receptor Binding Potential in Bipolar Disorder Depression is Associated with Treatment Remission: A Naturalistic Treatment Pilot PET Study

    PubMed Central

    Lan, Martin J; Hesselgrave, Natalie; Ciarleglio, Adam; Ogden, R Todd; Sullivan, Gregory M; Mann, J John; Parsey, Ramin V

    2013-01-01

    Bipolar Disorder is a major cause of disability and a high risk for suicide. The pathophysiology of the disorder remains largely unknown. Medication choice for bipolar depression patients involves trial and error. Our group reported previously that brain serotonin 1A (5HT1A) receptor binding measured by positron emission tomography (PET) is higher in bipolar depression. We now investigated whether pretreatment 5HT1A levels correlates with antidepressant medication outcome. 41 medication-free DSM-IV diagnosed, bipolar patients in a major depressive episode (MDE) had brain PET scans performed using [11C]WAY-100635 and a metabolite corrected arterial input function. The patients then received naturalistic psychopharmacologic treatment as outpatients and a follow up Hamilton Depression Rating Scale (HDRS) after 3 months of treatment. Patients with 24 item HDRS scores less than 10 were considered to have remitted. A linear mixed effects model was used to compare BPF (binding potential, proportional to the total number of available receptors) in 13 brain regions of interest between remitters and non-remitters. 34 patients completed 3 months of treatment and ratings; 9 had remitted. Remitters and non-remitters did not differ in age, sex or recent medication history with serotonergic medications. Remitters had higher [11C]WAY-100635 BPF across all brain regions compared with non-remitters (p=0.02). Higher pre-treatment brain 5HT1A receptor binding was associated with remission after 3 months of pharmacological treatment in bipolar depression. Prospective treatment studies are warranted to determine whether this test predicts outcome of specific types of treatment. PMID:23720414

  11. Higher pretreatment 5-HT1A receptor binding potential in bipolar disorder depression is associated with treatment remission: a naturalistic treatment pilot PET study.

    PubMed

    Lan, Martin J; Hesselgrave, Natalie; Ciarleglio, Adam; Ogden, R Todd; Sullivan, Gregory M; Mann, J John; Parsey, Ramin V

    2013-11-01

    Bipolar disorder is a major cause of disability and a high risk for suicide. The pathophysiology of the disorder remains largely unknown. Medication choice for bipolar depression patients involves trial and error. Our group reported previously that brain serotonin 1A (5-HT(1A)) receptor binding measured by positron emission tomography (PET) is higher in bipolar depression. We now investigated whether pretreatment 5-HT(1A) levels correlates with antidepressant medication outcome. Forty-one medication-free DSM-IV diagnosed, bipolar patients in a major depressive episode had brain PET scans performed using [(11)C]WAY-100635 and a metabolite corrected arterial input function. The patients then received naturalistic psychopharmacologic treatment as outpatients and a follow up Hamilton Depression Rating Scale (HDRS) after 3 months of treatment. Patients with 24 item HDRS scores less than 10 were considered to have remitted. A linear mixed effects model was used to compare BP(F) (binding potential, proportional to the total number of available receptors) in 13 brain regions of interest between remitters and nonremitters. Thirty-four patients completed 3 months of treatment and ratings; 9 had remitted. Remitters and nonremitters did not differ in age, sex, or recent medication history with serotonergic medications. Remitters had higher [(11)C]WAY-100635 BP(F) across all brain regions compared with nonremitters (P = 0.02). Higher pretreatment brain 5-HT(1A) receptor binding was associated with remission after 3 months of pharmacological treatment in bipolar depression. Prospective treatment studies are warranted to determine whether this test predicts outcome of specific types of treatment.

  12. Measurement of 5-HT(1A) receptor density and in-vivo binding parameters of [(18)F]mefway in the nonhuman primate.

    PubMed

    Wooten, Dustin W; Hillmer, Ansel T; Moirano, Jeffrey M; Ahlers, Elizabeth O; Slesarev, Maxim; Barnhart, Todd E; Mukherjee, Jogeshwar; Schneider, Mary L; Christian, Bradley T

    2012-08-01

    The goal of this work was to characterize the in-vivo behavior of [(18)F]mefway as a suitable positron emission tomography (PET) radiotracer for the assay of 5-hydroxytryptamine(1A) (5-HT(1A)) receptor density (B(max)). Six rhesus monkeys were studied using a multiple-injection (M-I) protocol consisting of three sequential bolus injections of [(18)F]mefway. Injection times and amounts of unlabeled mefway were optimized for the precise measurement of B(max) and specific binding parameters k(off) and k(on) for estimation of apparent K(D). The PET time series were acquired for 180 minutes with arterial sampling performed throughout. Compartmental analysis using the arterial input function was performed to obtain estimates for K(1), k(2), k(off), B(max), and K(Dapp) in the cerebral cortex and raphe nuclei (RN) using a model that accounted for nontracer doses of mefway. Averaged over subjects, highest binding was seen in the mesial temporal and dorsal anterior cingulate cortices with B(max) values of 42±8 and 36±8 pmol/mL, respectively, and lower values in the superior temporal cortex, RN, and parietal cortex of 24±4, 19±4, and 13±2 pmol/mL, respectively. The K(Dapp) of mefway for the 5-HT(1A) receptor sites was 4.3±1.3 nmol/L. In conclusion, these results show that M-I [(18)F]mefway PET experiments can be used for the in-vivo measurement of 5-HT(1A) receptor density.

  13. Women with Multiple Chemical Sensitivity Have Increased Harm Avoidance and Reduced 5-HT1A Receptor Binding Potential in the Anterior Cingulate and Amygdala

    PubMed Central

    Åhs, Fredrik; Savic, Ivanka

    2013-01-01

    Multiple chemical sensitivity (MCS) is a common condition, characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the underlying mechanisms are unknown. Contrary to the expectations it was recently found that persons with MCS activate the odor-processing brain regions less than controls, while their activation of the anterior cingulate cortex (ACC) is increased. The present follow-up study was designed to test the hypotheses that MCS subjects have increased harm avoidance and deviations in the serotonin system, which could render them intolerant to environmental odors. Twelve MCS and 11 control subjects, age 22–44, all working or studying females, were included in a PET study where 5-HT1A receptor binding potential (BP) was assessed after bolus injection of [11C]WAY100635. Psychological profiles were assessed by the Temperament and Character Inventory and the Swedish universities Scales of Personality. All MCS and 12 control subjects were also tested for emotional startle modulation in an acoustic startle test. MCS subjects exhibited significantly increased harm avoidance, and anxiety compared to controls. They also had a reduced 5-HT1A receptor BP in amygdala (p = 0.029), ACC (p = 0.005) (planned comparisons, significance level 0.05), and insular cortex (p = 0.003; significance level p<0.005 with Bonferroni correction), and showed an inverse correlation between degree of anxiety and the BP in the amygdala (planned comparison). No group by emotional category difference was found in the startle test. Increased harm avoidance and the observed changes in the 5-HT1A receptor BP in the regions processing harm avoidance provides a plausible pathophysiological ground for the symptoms described in MCS, and yields valuable information for our general understanding of idiopathic environmental intolerances. PMID:23349968

  14. Metabolic and Cardiovascular Benefits and Risks of EMD386088—A 5-HT6 Receptor Partial Agonist and Dopamine Transporter Inhibitor

    PubMed Central

    Kotańska, Magdalena; Śniecikowska, Joanna; Jastrzębska-Więsek, Magdalena; Kołaczkowski, Marcin; Pytka, Karolina

    2017-01-01

    Since 5-HT6 receptors play role in controlling feeding and satiety and dopamine is essential for normal feeding behavior, we evaluated the ability of EMD 386088—5-HT6 receptor partial agonist and dopamine transporter inhibitor—to reduce body weight in obese rats, as well as its anorectic properties (calorie intake reduction) in rat model of excessive eating and the influence on metabolism (plasma glucose and glycerol levels). We also determined the effect of the studied compound on pica behavior in rats and its influence on blood pressure after single administration. EMD 386088 reduced body weight in obese rats fed high-fat diet and decreased calorie intake in both models applied (rat model of obesity and of excessive eating). In both models EMD 386088 regulated plasma glucose and increased plasma glycerol levels. The latter proves that the compound reduced body fat. We think that it might have increased lipolysis, but this requires further studies. The reduction in glucose levels is the first symptom of metabolic disorders compensation. EMD 386088 did not cause pica behavior in rats but increased blood pressure after single administration. We think that partial 5-HT6 agonists might have potential in the treatment of obesity. Thus, EMD 386088 requires extended studies. PMID:28228713

  15. Mode of action of peppermint oil and (-)-menthol with respect to 5-HT3 receptor subtypes: binding studies, cation uptake by receptor channels and contraction of isolated rat ileum.

    PubMed

    Heimes, Katharina; Hauk, Florian; Verspohl, Eugen J

    2011-05-01

    Peppermint oil (Mentha × piperita L. (Lamiaceae) has been shown to exert potent antiemetic properties, but its mode of action has not yet been elucidated. Among its active constituents (-)-menthol is the most important. Three different in vitro models were used to investigate the effects on 5-HT(3) receptors (serotonin receptor subtype): [(14)C]guanidinium influx into N1E-115 cells which express 5-HT(3) receptors, isotonic contractions of the isolated rat ileum and equilibrium competition binding studies using a radioactively labelled 5-HT(3) receptor antagonist ([(3)H]GR65630) (3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1-propanone). Both peppermint oil and (-)-menthol inhibited [(14)C]guanidinium influx through 5-HT(3) receptor channels as well as contractions of the ileum induced by serotonin. Neither the peppermint oil nor (-)-menthol, however, was able to displace [(3)H]GR65630 from 5-HT(3) binding sites. It may be concluded that peppermint oil and (-)-menthol exert their antiemetic effect at least partly by acting on the 5-HT(3) receptor ion-channel complex, probably by binding to a modulatory site distinct from the serotonin binding site.

  16. COMMUNICATION BETWEEN 5-HT AND SMALL GTPases

    PubMed Central

    Mercado, Charles P.; Ziu, Endrit; Kilic, Fusun

    2011-01-01

    Advances over the past decade have improved our understanding of the serotonin (5-HT) biology outside the central nervous system specifically the molecular mechanisms of serotonergic signaling in association with small GTPases. It is now recognized that the communication between 5-HT and GTPases plays important roles in peripheral tissues, vascular cells and are involved in coagulation, hypertension, inflammation, healing and protection. Furthermore, 5-HT receptors as heterotrimeric GTP-binding protein-coupled receptors act as effector protein on the small GTPases. Therefore, the antagonists or agonists of the effector proteins of small GTPases could be useful therapeutic agents for the treatment of several diseases and disorders. PMID:21320798

  17. Measuring endogenous 5-HT release by emission tomography: promises and pitfalls

    PubMed Central

    Paterson, Louise M; Tyacke, Robin J; Nutt, David J; Knudsen, Gitte M

    2010-01-01

    Molecular in vivo neuroimaging techniques can be used to measure regional changes in endogenous neurotransmitters, evoked by challenges that alter synaptic neurotransmitter concentration. This technique has most successfully been applied to the study of endogenous dopamine release using positron emission tomography, but has not yet been adequately extended to other neurotransmitter systems. This review focuses on how the technique has been applied to the study of the 5-hydroxytryptamine (5-HT) system. The principles behind visualising fluctuations in neurotransmitters are introduced, with reference to the dopaminergic system. Studies that aim to image acute, endogenous 5-HT release or depletion at 5-HT receptor targets are summarised, with particular attention to studies in humans. Radiotracers targeting the 5-HT1A, 5-HT2A, and 5-HT4 receptors and the serotonin reuptake transporter have been explored for their sensitivity to 5-HT fluctuations, but with mixed outcomes; tracers for these targets cannot reliably image endogenous 5-HT in humans. Shortcomings in our basic knowledge of the mechanisms underlying changes in binding potential are addressed, and suggestions are made as to how the selection of targets, radiotracers, challenge paradigms, and experimental design might be optimised to improve our chances of successfully imaging endogenous neurotransmitters in the future. PMID:20664611

  18. 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.

  19. Design and synthesis of dual 5-HT1A and 5-HT7 receptor ligands.

    PubMed

    Ofori, Edward; Zhu, Xue Y; Etukala, Jagan R; Peprah, Kwakye; Jordan, Kamanski R; Adkins, Adia A; Bricker, Barbara A; Kang, Hye J; Huang, Xi-Ping; Roth, Bryan L; Ablordeppey, Seth Y

    2016-08-15

    5-HT1A and 5-HT7 receptors have been at the center of discussions recently due in part to their major role in the etiology of major central nervous system diseases such as depression, sleep disorders, and schizophrenia. As part of our search to identify dual targeting ligands for these receptors, we have carried out a systematic modification of a selective 5HT7 receptor ligand culminating in the identification of several dual 5-HT1A and 5-HT7 receptor ligands. Compound 16, a butyrophenone derivative of tetrahydroisoquinoline (THIQ), was identified as the most potent agent with low nanomolar binding affinities to both receptors. Interestingly, compound 16 also displayed moderate affinity to other clinically relevant dopamine receptors. Thus, it is anticipated that compound 16 may serve as a lead for further exploitation in our quest to identify new ligands with the potential to treat diseases of CNS origin.

  20. Serotonin 5-HT1A receptors as targets for agents to treat psychiatric disorders: rationale and current status of research.

    PubMed

    Celada, Pau; Bortolozzi, Analía; Artigas, Francesc

    2013-09-01

    Psychiatric disorders represent a large economic burden in modern societies. However, pharmacological treatments are still far from optimal. Drugs used in the treatment of major depressive disorder (MDD) and anxiety disorders (selective serotonin [5-HT] reuptake inhibitors [SSRIs] and serotonin-noradrenaline reuptake inhibitors [SNRIs]) are pharmacological refinements of first-generation tricyclic drugs, discovered by serendipity, and show low efficacy and slowness of onset. Moreover, antipsychotic drugs are partly effective in positive symptoms of schizophrenia, yet they poorly treat negative symptoms and cognitive deficits. The present article reviews the neurobiological basis of 5-HT1A receptor (5-HT1A-R) function and the role of pre- and postsynaptic 5-HT1A-Rs in the treatment of MDD, anxiety and psychotic disorders. The activation of postsynaptic 5-HT1A-Rs in corticolimbic areas appears beneficial for the therapeutic action of antidepressant drugs. However, presynaptic 5-HT1A-Rs play a detrimental role in MDD, since individuals with high density or function of presynaptic 5-HT1A-Rs are more susceptible to mood disorders and suicide, and respond poorly to antidepressant drugs. Moreover, the indirect activation of presynaptic 5-HT1A-Rs by SSRIs/SNRIs reduces 5-HT neuron activity and terminal 5-HT release, thus opposing the elevation of extracellular 5-HT produced by blockade of the serotonin transporter (SERT) in the forebrain. Chronic antidepressant treatment desensitizes presynaptic 5-HT1A-Rs, thus reducing the effectiveness of the 5-HT1A autoreceptor-mediated negative feedback. The prevention of this process by the non-selective partial agonist pindolol accelerates clinical antidepressant effects. Two new antidepressant drugs, vilazodone (marketed in the USA) and vortioxetine (in development) incorporate partial 5-HT1A-R agonist properties with SERT blockade. Several studies with transgenic mice have also established the respective role of pre- and

  1. Synergistic Effect between Maternal Infection and Adolescent Cannabinoid Exposure on Serotonin 5HT1A Receptor Binding in the Hippocampus: Testing the “Two Hit” Hypothesis for the Development of Schizophrenia

    PubMed Central

    Dalton, Victoria S.; Verdurand, Mathieu; Walker, Adam; Hodgson, Deborah M.; Zavitsanou, Katerina

    2012-01-01

    Infections during pregnancy and adolescent cannabis use have both been identified as environmental risk factors for schizophrenia. We combined these factors in an animal model and looked at their effects, alone and in combination, on serotonin 5HT1A receptor binding (5HT1AR) binding longitudinally from late adolescence to adulthood. Pregnant rats were exposed to the viral mimic poly I:C on embryonic day 15. Adolescent offspring received daily injections of the cannabinoid HU210 for 14 days starting on postnatal day (PND) 35. Hippocampal and cortical 5HT1AR binding was quantified autoradiographically using [3H]8-OH-DPAT, in late adolescent (PND 55), young adult (PND 65) and adult (PND 90) rats. Descendants of poly I:C treated rats showed significant increases of 15–18% in 5HT1AR in the hippocampus (CA1) compared to controls at all developmental ages. Offspring of poly I:C treated rats exposed to HU210 during adolescence exhibited even greater elevations in 5HT1AR (with increases of 44, 29, and 39% at PNDs 55, 65, and 90). No effect of HU210 alone was observed. Our results suggest a synergistic effect of prenatal infection and adolescent cannabinoid exposure on the integrity of the serotoninergic system in the hippocampus that may provide the neurochemical substrate for abnormal hippocampal-related functions relevant to schizophrenia. PMID:23738203

  2. A Hybrid Structural Approach to Analyze Ligand Binding by the Serotonin Type 4 Receptor (5-HT4)*

    PubMed Central

    Padayatti, Pius S.; Wang, Liwen; Gupta, Sayan; Orban, Tivadar; Sun, Wenyu; Salom, David; Jordan, Steven R.; Palczewski, Krzysztof; Chance, Mark R.

    2013-01-01

    Hybrid structural methods have been used in recent years to understand protein-protein or protein-ligand interactions where high resolution crystallography or NMR data on the protein of interest has been limited. For G protein-coupled receptors (GPCRs), high resolution structures of native structural forms other than rhodopsin have not yet been achieved; gaps in our knowledge have been filled by creative crystallography studies that have developed stable forms of receptors by multiple means. The neurotransmitter serotonin (5-hydroxytryptamine) is a key GPCR-based signaling molecule affecting many physiological manifestations in humans ranging from mood and anxiety to bowel function. However, a high resolution structure of any of the serotonin receptors has not yet been solved. Here, we used structural mass spectrometry along with theoretical computations, modeling, and other biochemical methods to develop a structured model for human serotonin receptor subtype 4(b) in the presence and absence of its antagonist GR125487. Our data confirmed the overall structure predicted by the model and revealed a highly conserved motif in the ligand-binding pocket of serotonin receptors as an important participant in ligand binding. In addition, identification of waters in the transmembrane region provided clues as to likely paths mediating intramolecular signaling. Overall, this study reveals the potential of hybrid structural methods, including mass spectrometry, to probe physiological and functional GPCR-ligand interactions with purified native protein. PMID:23378516

  3. Role of 5-HT6 receptors in memory formation.

    PubMed

    Meneses, A

    2001-09-01

    Mice lacking the 5-HT(6) receptor presented neither gross anatomical or behavioral abnormalities nor obvious changes in microscopic brain morphology, and their performance in rotarod, open field and novel object testing paradigms revealed no differences compared with wild-type animals. Nevertheless, an association between the 5-HT(6) receptor polymorphism C267T and Alzheimer's disease has been reported. Interestingly, the 5-HT(6) antisense oligonucleotide decreased 5-HT(6) gene expression and enhanced spatial learning acquisition in the water maze. Similarly, injection of the 5-HT(6) receptor antagonist Ro-04-6790 improved learning consolidation in an autoshaping task, while mCPP, scopolamine and dizocilpine decreased performance. The effect induced by scopolamine or dizocilpine, but not that induced by mCPP, was completely or partially reversed by Ro-04-6790. Ro-04-6790 did not modify the 8-OH-DPAT facilitatory effects on learning consolidation. Since Ro-04-6790 facilitatory effect was unaffected by 5-HT(1A), 5-HT(2A/2B/2C), 5-HT(3), 5-HT(4) or 5-HT(7) receptor blockade, the facilitatory effect induced by Ro-04-6790 involved specifically 5-HT6 receptors. Similarly, the 5-HT(6) receptor antagonist SB-271046 improved retention in the water maze and produced a significant performance improvement in aged rats in an operant-delayed alternation task. A series of Ro-04-6790 analogues that penetrate the brain and specifically bind to 5-HT(6) receptors reversed scopolamine-induced retention deficit in a passive avoidance learning test. Collectively, these data provide further support to the notion that 5-HT systems, via 5-HT(6) receptors, also play a significant role in memory formation under normal and dysfunctional memory conditions.

  4. Conservation of 5-HT1A receptor-mediated autoinhibition of serotonin (5-HT) neurons in mice with altered 5-HT homeostasis.

    PubMed

    Araragi, Naozumi; Mlinar, Boris; Baccini, Gilda; Gutknecht, Lise; Lesch, Klaus-Peter; Corradetti, Renato

    2013-01-01

    Firing activity of serotonin (5-HT) neurons in the dorsal raphe nucleus (DRN) is controlled by inhibitory somatodendritic 5-HT1A autoreceptors. This autoinhibitory mechanism is implicated in the etiology of disorders of emotion regulation, such as anxiety disorders and depression, as well as in the mechanism of antidepressant action. Here, we investigated how persistent alterations in brain 5-HT availability affect autoinhibition in two genetically modified mouse models lacking critical mediators of serotonergic transmission: 5-HT transporter knockout (Sert-/-) and tryptophan hydroxylase-2 knockout (Tph2-/-) mice. The degree of autoinhibition was assessed by loose-seal cell-attached recording in DRN slices. First, application of the 5-HT1A-selective agonist R(+)-8-hydroxy-2-(di-n-propylamino)tetralin showed mild sensitization and marked desensitization of 5-HT1A receptors in Tph2-/- mice and Sert-/- mice, respectively. While 5-HT neurons from Tph2-/- mice did not display autoinhibition in response to L-tryptophan, autoinhibition of these neurons was unaltered in Sert-/- mice despite marked desensitization of their 5-HT1A autoreceptors. When the Tph2-dependent 5-HT synthesis step was bypassed by application of 5-hydroxy-L-tryptophan (5-HTP), neurons from both Tph2-/- and Sert-/- mice decreased their firing rates at significantly lower concentrations of 5-HTP compared to wildtype controls. Our findings demonstrate that, as opposed to the prevalent view, sensitivity of somatodendritic 5-HT1A receptors does not predict the magnitude of 5-HT neuron autoinhibition. Changes in 5-HT1A receptor sensitivity may rather be seen as an adaptive mechanism to keep autoinhibition functioning in response to extremely altered levels of extracellular 5-HT resulting from targeted inactivation of mediators of serotonergic signaling.

  5. Long-term estrogen therapy and 5-HT(2A) receptor binding in postmenopausal women; a single photon emission tomography (SPET) study.

    PubMed

    Compton, J; Travis, M J; Norbury, R; Erlandsson, K; van Amelsvoort, T; Daly, E; Waddington, W; Matthiasson, P; Eersels, J L H; Whitehead, M; Kerwin, R W; Ell, P J; Murphy, D G M

    2008-01-01

    Variation in estrogen level is reported by some to affect brain maturation and memory. The neurobiological basis for this may include modulation of the serotonergic system. No neuroimaging studies have directly examined the effect of extended estrogen therapy (ET), on the 5-HT(2A) receptor in human brain. We investigated the effect of long-term ET on cortical 5-HT(2A) receptor availability in postmenopausal women. In a cross-sectional study, we compared cortical 5-HT(2A) receptor availability in 17 postmenopausal ERT-naive women and 17 long-term oophorectomised estrogen-users, age- and IQ-matched using single photon emission tomography and the selective 5-HT(2A) receptor ligand (123)I-5-I-R91150. Also, we used the Revised Wechsler Memory Scale to relate memory function to 5-HT(2A) receptor availability. Never-users had significantly higher 5-HT(2A) receptor availability than estrogen-users in hippocampus (1.17 vs. 1.11, respectively, p=0.02), although this did not remain significant after correction for multiple comparisons. Hippocampal 5-HT(2A) receptor availability correlated negatively with verbal and general memory and delayed recall (r=-0.45, p=0.01; r=-0.40, p=0.02; r=-0.36, p=0.04). Right superior temporal 5-HT(2A) receptor availability correlated negatively with verbal memory (r=-0.36, p=0.04). In estrogen-users, receptor availability correlated negatively with verbal and general memory (r=-0.70, p=0.002; r=-0.69, p=0.002); and in never-users, receptor availability negatively correlated with attention and concentration (r=-0.54, p=0.02). Long-term ET may be associated with lower 5-HT(2A) receptor availability in hippocampus. This may reflect increased activity within the serotonergic pathway leading to down-regulation of post-synaptic receptor. Also, increased availability of the 5-HT(2A) receptor in hippocampus is associated with poorer memory function.

  6. A new serotonin 5-HT6 receptor antagonist with procognitive activity – Importance of a halogen bond interaction to stabilize the binding

    NASA Astrophysics Data System (ADS)

    González-Vera, Juan A.; Medina, Rocío A.; Martín-Fontecha, Mar; Gonzalez, Angel; de La Fuente, Tania; Vázquez-Villa, Henar; García-Cárceles, Javier; Botta, Joaquín; McCormick, Peter J.; Benhamú, Bellinda; Pardo, Leonardo; López-Rodríguez, María L.

    2017-01-01

    Serotonin 5-HT6 receptor has been proposed as a promising therapeutic target for cognition enhancement though the development of new antagonists is still needed to validate these molecules as a drug class for the treatment of Alzheimer’s disease and other pathologies associated with memory deficiency. As part of our efforts to target the 5-HT6 receptor, new benzimidazole-based compounds have been designed and synthesized. Site-directed mutagenesis and homology models show the importance of a halogen bond interaction between a chlorine atom of the new class of 5-HT6 receptor antagonists identified herein and a backbone carbonyl group in transmembrane domain 4. In vitro pharmacological characterization of 5-HT6 receptor antagonist 7 indicates high affinity and selectivity over a panel of receptors including 5-HT2B subtype and hERG channel, which suggests no major cardiac issues. Compound 7 exhibited in vivo procognitive activity (1 mg/kg, ip) in the novel object recognition task as a model of memory deficit.

  7. A new serotonin 5-HT6 receptor antagonist with procognitive activity – Importance of a halogen bond interaction to stabilize the binding

    PubMed Central

    González-Vera, Juan A.; Medina, Rocío A.; Martín-Fontecha, Mar; Gonzalez, Angel; de la Fuente, Tania; Vázquez-Villa, Henar; García-Cárceles, Javier; Botta, Joaquín; McCormick, Peter J.; Benhamú, Bellinda; Pardo, Leonardo; López-Rodríguez, María L.

    2017-01-01

    Serotonin 5-HT6 receptor has been proposed as a promising therapeutic target for cognition enhancement though the development of new antagonists is still needed to validate these molecules as a drug class for the treatment of Alzheimer’s disease and other pathologies associated with memory deficiency. As part of our efforts to target the 5-HT6 receptor, new benzimidazole-based compounds have been designed and synthesized. Site-directed mutagenesis and homology models show the importance of a halogen bond interaction between a chlorine atom of the new class of 5-HT6 receptor antagonists identified herein and a backbone carbonyl group in transmembrane domain 4. In vitro pharmacological characterization of 5-HT6 receptor antagonist 7 indicates high affinity and selectivity over a panel of receptors including 5-HT2B subtype and hERG channel, which suggests no major cardiac issues. Compound 7 exhibited in vivo procognitive activity (1 mg/kg, ip) in the novel object recognition task as a model of memory deficit. PMID:28117458

  8. A new serotonin 5-HT6 receptor antagonist with procognitive activity - Importance of a halogen bond interaction to stabilize the binding.

    PubMed

    González-Vera, Juan A; Medina, Rocío A; Martín-Fontecha, Mar; Gonzalez, Angel; de la Fuente, Tania; Vázquez-Villa, Henar; García-Cárceles, Javier; Botta, Joaquín; McCormick, Peter J; Benhamú, Bellinda; Pardo, Leonardo; López-Rodríguez, María L

    2017-01-24

    Serotonin 5-HT6 receptor has been proposed as a promising therapeutic target for cognition enhancement though the development of new antagonists is still needed to validate these molecules as a drug class for the treatment of Alzheimer's disease and other pathologies associated with memory deficiency. As part of our efforts to target the 5-HT6 receptor, new benzimidazole-based compounds have been designed and synthesized. Site-directed mutagenesis and homology models show the importance of a halogen bond interaction between a chlorine atom of the new class of 5-HT6 receptor antagonists identified herein and a backbone carbonyl group in transmembrane domain 4. In vitro pharmacological characterization of 5-HT6 receptor antagonist 7 indicates high affinity and selectivity over a panel of receptors including 5-HT2B subtype and hERG channel, which suggests no major cardiac issues. Compound 7 exhibited in vivo procognitive activity (1 mg/kg, ip) in the novel object recognition task as a model of memory deficit.

  9. Effect of mouse chromosome 13 terminal fragment on liability to catalepsy and expression of tryptophane hydroxylase-2, serotonin transporter, and 5-HT1A receptor genes in the brain.

    PubMed

    Kulikov, A V; Naumenko, V S; Bazovkina, D V; Dee, V Yu; Osipova, D V; Popova, N K

    2009-05-01

    Congenic mice obtained by genome fragments transfer from one strain to another are a potent tool for studies of the molecular mechanisms of behavioral mutations. The 59-70 cM fragment of chromosome 13 containing the locus determining predisposition to freezing reaction (catalepsy) and the gene encoding 5-HT(1A) receptor were transferred from cataleptic CBA/Lac mice into the genome of catalepsy-resistant AKR/J mice. The impact of this fragment for the severity of catalepsy and expression of genes encoding tryptophane hydroxylase-2, serotonin transporter, and 5-HT(1A) receptor was studied. Half of mice of the resultant congenic AKR.CBA-D13Mit76 strain exhibited pronounced catalepsy, similarly to donor CBA animals. The expression of 5-HT(1A) receptor gene in the midbrain of AKR animals was significantly higher than in CBA. The level of 5-HT(1A) receptor mRNA in AKR.CBA-D13Mit76 animals was significantly higher than in the donor strain. Mice of parental AKR and CBA strains did not differ from each other and from AKR.CBA-D13Mit76 animals by the levels of tryptophane hydroxylase-2 and serotonin transporter genes mRNA. These data prove the location of catalepsy regulating gene in the distal fragment of chromosome 13. The recipient strain genome enhanced the expression of 5-HT(1A) receptor gene in the brain without modulating the expression of catalepsy gene.

  10. The rapid recovery of 5-HT cell firing induced by the antidepressant vortioxetine involves 5-HT(3) receptor antagonism.

    PubMed

    Bétry, Cécile; Pehrson, Alan L; Etiévant, Adeline; Ebert, Bjarke; Sánchez, Connie; Haddjeri, Nasser

    2013-06-01

    The therapeutic effect of current antidepressant drugs appears after several weeks of treatment and a significant number of patients do not respond to treatment. Here, we report the effects of the multi-modal antidepressant vortioxetine (Lu AA21004), a 5-HT(3) and 5-HT(7) receptor antagonist, 5-HT(1B) receptor partial agonist, 5-HT(1A) receptor agonist and 5-HT transporter (SERT) inhibitor, on rat 5-HT neurotransmission. Using in vivo electrophysiological recordings in the dorsal raphe nucleus of anaesthetized rats, we assessed the acute and subchronic effects of vortioxetine and/or the selective 5-HT(3) receptor agonist, SR57227 or the selective 5-HT(1A) receptor agonist flesinoxan, on 5-HT neuronal firing activity. Using ex-vivo autoradiography, we correlated SERT occupancy and presumed 5-HT firing activity. The selective serotonin reuptake inhibitor, fluoxetine, was used as comparator. Importantly, the recovery of 5-HT neuronal firing was achieved after 1 d with vortioxetine and 14 d with fluoxetine. SR57227 delayed this recovery. In contrast, vortioxetine failed to alter the reducing action of 3 d treatment of flesinoxan. Acute dosing of vortioxetine inhibited neuronal firing activity more potently than fluoxetine. SR57227 prevented the suppressant effect of vortioxetine, but not of fluoxetine. In contrast, flesinoxan failed to modify the suppressant effect of vortioxetine acutely administered. Differently to fluoxetine, vortioxetine suppressed neuronal firing without saturating occupancy at the SERT. Vortioxetine produced a markedly faster recovery of 5-HT neuronal firing than fluoxetine. This is at least partly due to 5-HT(3) receptor antagonism of vortioxetine in association with its reduced SERT occupancy.

  11. The arylpiperazine derivatives N-(4-cyanophenylmethyl)-4-(2-diphenyl)-1-piperazinehexanamide and N-benzyl-4-(2-diphenyl)-1-piperazinehexanamide exert a long-lasting inhibition of human serotonin 5-HT7 receptor binding and cAMP signaling.

    PubMed

    Atanes, Patricio; Lacivita, Enza; Rodríguez, Javier; Brea, José; Burgueño, Javier; Vela, José Miguel; Cadavid, María Isabel; Loza, María Isabel; Leopoldo, Marcello; Castro, Marián

    2013-12-01

    We performed a detailed in vitro pharmacological characterization of two arylpiperazine derivatives, compound N-(4-cyanophenylmethyl)-4-(2-diphenyl)-1-piperazinehexanamide (LP-211) previously identified as a high-affinity brain penetrant ligand for 5-hydroxytryptamine (serotonin) type 7 (5-HT7) receptors, and its analog N-benzyl-4-(2-diphenyl)-1-piperazinehexanamide (MEL-9). Both ligands exhibited competitive displacement of [(3)H]-(2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]pyrrolidine ([(3)H]-SB-269970) radioligand binding and insurmountable antagonism of 5-carboxamidotryptamine (5-CT)-stimulated cyclic adenosine monophosphate (cAMP) signaling in human embryonic kidney (HEK293) cells stably expressing human 5-HT7 receptors. They also inhibited forskolin-stimulated adenylate cyclase activity in 5-HT7-expressing HEK293 cells but not in the parental cell line. The compounds elicited long-lasting (at least 24 h) concentration-dependent inhibition of radioligand binding at 5-HT7-binding sites in whole-cell radioligand binding assays, after pretreatment of the cells with the compounds and subsequent compound removal. In cAMP assays, pretreatment of cells with the compounds rendered 5-HT7 receptors unresponsive to 5-CT and also rendered 5-HT7-expressing HEK293 cells unresponsive to forskolin. Compound 1-(2-biphenyl)piperazine (RA-7), a known active metabolite of LP-211 present in vivo, was able to partially inhibit 5-HT7 radioligand binding in a long-lasting irreversible manner. Hence, LP-211 and MEL-9 were identified as high-affinity long-acting inhibitors of human 5-HT7 receptor binding and function in cell lines. The detailed in vitro characterization of these two pharmacological tools targeting 5-HT7 receptors may benefit the study of 5-HT7 receptor function and it may lead to the development of novel selective pharmacological tools with defined functional properties at 5-HT7 receptors.

  12. 5-HT3 receptors as important mediators of nausea and vomiting due to chemotherapy.

    PubMed

    Navari, Rudolph M

    2015-10-01

    Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles, and patient risk factors significantly influence CINV. The use of a combination of a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist, dexamethasone, and a neurokinin-1 (NK-1) receptor antagonist has significantly improved the control of acute and delayed emesis in single-day chemotherapy. The first generation 5-HT3 receptor antagonists have been very effective in the control of chemotherapy induced emesis in the first 24 h postchemotherapy (acute emesis), but have not been as effective against delayed emesis (24-120 h postchemotherapy). Palonosetron, a second generation 5-HT3 receptor antagonist with a different half-life, a different binding capacity, and a different mechanism of action than the first generation 5-HT3 receptor antagonists appears to be the most effective agent in its class. Despite the control of emesis, nausea has not been well controlled by current agents. Olanzapine, a FDA approved antipsychotic that blocks multiple neurotransmitters: dopamine at D1, D2, D3, D4 brain receptors, serotonin at 5-HT2a, 5-HT2c, 5-HT3, 5-HT6 receptors, catecholamines at alpha1 adrenergic receptors, acetylcholine at muscarinic receptors, and histamine at H1 receptors, has emerged in recent trials as an effective preventative agent for chemotherapy-induced emesis and nausea, as well as a very effective agent for the treatment of breakthrough emesis and nausea. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  13. Serotonin (5-HT) 5-HT2A Receptor (5-HT2AR):5-HT2CR Imbalance in Medial Prefrontal Cortex Associates with Motor Impulsivity.

    PubMed

    Anastasio, Noelle C; Stutz, Sonja J; Fink, Latham H L; Swinford-Jackson, Sarah E; Sears, Robert M; DiLeone, Ralph J; Rice, Kenner C; Moeller, F Gerard; Cunningham, Kathryn A

    2015-07-15

    A feature of multiple neuropsychiatric disorders is motor impulsivity. Recent studies have implicated serotonin (5-HT) systems in medial prefrontal cortex (mPFC) in mediating individual differences in motor impulsivity, notably the 5-HT2AR receptor (5-HT2AR) and 5-HT2CR. We investigated the hypothesis that differences in the ratio of 5-HT2AR:5-HT2CR protein expression in mPFC would predict the individual level of motor impulsivity and that the engineered loss of the 5-HT2CR would result in high motor impulsivity concomitant with elevated 5-HT2AR expression and pharmacological sensitivity to the selective 5-HT2AR antagonist M100907. High and low impulsive rats were identified in a 1-choice serial reaction time task. Native protein levels of the 5-HT2AR and the 5-HT2CR predicted the intensity of motor impulsivity and the 5-HT2AR:5-HT2CR ratio in mPFC positively correlated with levels of premature responses in individual outbred rats. The possibility that the 5-HT2AR and 5-HT2CR act in concert to control motor impulsivity is supported by the observation that high phenotypic motor impulsivity associated with a diminished mPFC synaptosomal 5-HT2AR:5-HT2CR protein:protein interaction. Knockdown of mPFC 5-HT2CR resulted in increased motor impulsivity and triggered a functional disruption of the local 5-HT2AR:5-HT2CR balance as evidenced by a compensatory upregulation of 5-HT2AR protein expression and a leftward shift in the potency of M100907 to suppress impulsive behavior. We infer that there is an interactive relationship between the mPFC 5-HT2AR and 5-HT2CR, and that a 5-HT2AR:5-HT2CR imbalance may be a functionally relevant mechanism underlying motor impulsivity.

  14. Serotonin (5-HT) 5-HT2A Receptor (5-HT2AR):5-HT2CR Imbalance in Medial Prefrontal Cortex Associates with Motor Impulsivity

    PubMed Central

    Anastasio, Noelle C.; Stutz, Sonja J.; Fink, Latham H. L.; Swinford-Jackson, Sarah E.; Sears, Robert M; DiLeone, Ralph J.; Rice, Kenner C.; Moeller, F. Gerard; Cunningham, Kathryn A.

    2016-01-01

    A feature of multiple neuropsychiatric disorders is motor impulsivity. Recent studies have implicated serotonin (5-HT) systems in medial prefrontal cortex (mPFC) in mediating individual differences in motor impulsivity, notably the 5-HT2AR receptor (5-HT2AR) and 5-HT2CR. We investigated the hypothesis that differences in the ratio of 5-HT2AR:5-HT2CR protein expression in mPFC would predict the individual level of motor impulsivity and that the engineered loss of the 5-HT2CR would result in high motor impulsivity concomitant with elevated 5-HT2AR expression and pharmacological sensitivity to the selective 5-HT2AR antagonist M100907. High and low impulsive rats were identified in a 1-choice serial reaction time task. Native protein levels of the 5-HT2AR and the 5-HT2CR predicted the intensity of motor impulsivity and the 5-HT2AR:5-HT2CR ratio in mPFC positively correlated with levels of premature responses in individual outbred rats. The possibility that the 5-HT2AR and 5-HT2CR act in concert to control motor impulsivity is supported by the observation that high phenotypic motor impulsivity associated with a diminished mPFC synaptosomal 5-HT2AR:5-HT2CR protein:protein interaction. Knockdown of mPFC 5-HT2CR resulted in increased motor impulsivity and triggered a functional disruption of the local 5-HT2AR:5-HT2CR balance as evidenced by a compensatory upregulation of 5-HT2AR protein expression and a leftward shift in the potency of M100907 to suppress impulsive behavior. We infer that there is an interactive relationship between the mPFC 5-HT2AR and 5-HT2CR, and that a 5-HT2AR:5-HT2CR imbalance may be a functionally-relevant mechanism underlying motor impulsivity. PMID:26120876

  15. 5-HT1A and 5-HT7 receptor crosstalk in the regulation of emotional memory: implications for effects of selective serotonin reuptake inhibitors.

    PubMed

    Eriksson, Therese M; Holst, Sarah; Stan, Tiberiu L; Hager, Torben; Sjögren, Benita; Ogren, Sven Öve; Svenningsson, Per; Stiedl, Oliver

    2012-11-01

    This study utilized pharmacological manipulations to analyze the role of direct and indirect activation of 5-HT(7) receptors (5-HT(7)Rs) in passive avoidance learning by assessing emotional memory in male C57BL/6J mice. Additionally, 5-HT(7)R binding affinity and 5-HT(7)R-mediated protein phosphorylation of downstream signaling targets were determined. Elevation of 5-HT by the selective serotonin reuptake inhibitor (SSRI) fluoxetine had no effect by itself, but facilitated emotional memory performance when combined with the 5-HT(1A)R antagonist NAD-299. This facilitation was blocked by the selective 5-HT(7)R antagonist SB269970, revealing excitatory effects of the SSRI via 5-HT(7)Rs. The enhanced memory retention by NAD-299 was blocked by SB269970, indicating that reduced activation of 5-HT(1A)Rs results in enhanced 5-HT stimulation of 5-HT(7)Rs. The putative 5-HT(7)R agonists LP-44 when administered systemically and AS19 when administered both systemically and into the dorsal hippocampus failed to facilitate memory. This finding is consistent with the low efficacy of LP-44 and AS19 to stimulate protein phosphorylation of 5-HT(7)R-activated signaling cascades. In contrast, increasing doses of the dual 5-HT(1A)R/5-HT(7)R agonist 8-OH-DPAT impaired memory, while co-administration with NAD-299 facilitated of emotional memory in a dose-dependent manner. This facilitation was blocked by SB269970 indicating 5-HT(7)R activation by 8-OH-DPAT. Dorsohippocampal infusion of 8-OH-DPAT impaired passive avoidance retention through hippocampal 5-HT(1A)R activation, while 5-HT(7)Rs appear to facilitate memory processes in a broader cortico-limbic network and not the hippocampus alone.

  16. Multiple 5-HT receptors in the guinea-pig superior cervical ganglion.

    PubMed Central

    Watkins, C. J.; Newberry, N. R.

    1996-01-01

    1. We have studied the pharmacology of the depolarization by 5-hydroxytryptamine (5-HT) of the guinea-pig isolated superior cervical ganglion (SCG) using the grease-gap technique. We studied the effects of selective and non-selective antagonists on the responses to 5-HT and other 5-HT receptor agonists. 2. We have extended the pharmacology of the 5-HT3 receptor in this preparation by studying the effects of granisetron, BRL 46470 and mianserin on the concentration-response curve (CRC) to 2-methyl-5-HT. As with other 5-HT3 receptor antagonists, these compounds exhibited a lower affinity for guinea-pig 5-HT3 receptors than for rat 5-HT3 receptors. 3. We have confirmed that low concentrations of 5-HT (< or = 1 microM) mediate ketanserin-sensitive responses and higher concentrations of 5-HT also recruit 5-HT3 receptors. The responses to low concentrations of 5-HT were antagonized by low concentrations of ketanserin, spiperone, mianserin, DOI and LSD indicating probably mediation by 5-HT2A receptors. At high concentrations, the hallucinogen, DOI, but not LSD, evoked a ketanserin-sensitive depolarization. 4. Although mianserin could bind to the 5-HT2A receptors in this preparation, we could not demonstrate a down-regulation of depolarizations evoked by these receptors after a 10 day oral treatment with mianserin (10 mg kg-1, daily). 5. 5-Carboxamidotryptamine (5-CT) evoked a prolonged depolarization. Although high concentrations of 5-CT (> or = microM) appeared to activate 5-HT2A receptors, lower concentrations of 5-CT evoked a response with a distinct pharmacology. After studying the action of 20 selective and non-selective 5-HT receptor ligands we believe that this response may be mediated by a novel receptor; but its pharmacology is closest to that of receptors in the 5-HT2 receptor family. Like 5-CT, 5-HT (3-300 microM) could evoke an LSD-sensitive response in the presence of the 5-HT2 receptor antagonist, ketanserin and the 5-HT3 receptor antagonist, tropisetron

  17. Vortioxetine, but not escitalopram or duloxetine, reverses memory impairment induced by central 5-HT depletion in rats: evidence for direct 5-HT receptor modulation.

    PubMed

    Jensen, Jesper Bornø; du Jardin, Kristian Gaarn; Song, Dekun; Budac, David; Smagin, Gennady; Sanchez, Connie; Pehrson, Alan Lars

    2014-01-01

    Depressed patients suffer from cognitive dysfunction, including memory deficits. Acute serotonin (5-HT) depletion impairs memory and mood in vulnerable patients. The investigational multimodal acting antidepressant vortioxetine is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, 5-HT1B receptor partial agonist, 5-HT1A receptor agonist and 5-HT transporter (SERT) inhibitor that enhances memory in normal rats in novel object recognition (NOR) and conditioned fear (Mørk et al., 2013). We hypothesized that vortioxetine's 5-HT receptor mechanisms are involved in its memory effects, and therefore investigated these effects in 5-HT depleted rats. Four injections of the irreversible tryptophan hydroxylase inhibitor 4-chloro-dl-phenylalanine methyl ester hydrochloride (PCPA, 86mg/kg, s.c.) induced 5-HT depletion, as measured in hippocampal homogenate and microdialysate. The effects of acute challenge with vortioxetine or the 5-HT releaser fenfluramine on extracellular 5-HT were measured in PCPA-treated and control rats. PCPA's effects on NOR and spontaneous alternation (SA) performance were assessed along with the effects of acute treatment with 5-hydroxy-l-tryptophan (5-HTP), vortioxetine, the selective 5-HT reuptake inhibitor escitalopram, or the 5-HT norepinephrine reuptake inhibitor duloxetine. SERT occupancies were estimated by ex vivo autoradiography. PCPA depleted central 5-HT by >90% in tissue and microdialysate, and impaired NOR and SA performance. Restoring central 5-HT with 5-HTP reversed these deficits. At similar SERT occupancies (>90%) vortioxetine, but not escitalopram or duloxetine, restored memory performance. Acute fenfluramine significantly increased extracellular 5-HT in control and PCPA-treated rats, while vortioxetine did so only in control rats. Thus, vortioxetine restores 5-HT depletion impaired memory performance in rats through one or more of its receptor activities.

  18. 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.

  19. Serotonin (5-HT) regulates neurite outgrowth through 5-HT1A and 5-HT7 receptors in cultured hippocampal neurons.

    PubMed

    Rojas, Paulina S; Neira, David; Muñoz, Mauricio; Lavandero, Sergio; Fiedler, Jenny L

    2014-08-01

    Serotonin (5-HT) production and expression of 5-HT receptors (5-HTRs) occur early during prenatal development. Recent evidence suggests that, in addition to its classical role as a neurotransmitter, 5-HT regulates neuronal connectivity during mammalian development by modulating cell migration and neuronal cytoarchitecture. Given the variety of 5-HTRs, researchers have had difficulty clarifying the specific role of each receptor subtype in brain development. Signalling mediated by the G-protein-coupled 5-HT1A R and 5-HT7 R, however, has been associated with neuronal plasticity. Thus, we hypothesized that 5-HT promotes neurite outgrowth through 5-HT1A R and 5-HT7 R. The involvement of 5-HT1A R and 5-HT7 R in the morphology of rat hippocampal neurons was evaluated by treating primary cultures at 2 days in vitro with 5-HT and specific antagonists for 5-HT1A R and 5-HT7 R (WAY-100635 and SB269970, respectively). The stimulation of hippocampal neurons with 100 nM 5-HT for 24 hr produced no effect on either the number or the length of primary neurites. Nonetheless, after 5HT7 R was blocked, the addition of 5-HT increased the number of primary neurites, suggesting that 5HT7 R could inhibit neuritogenesis. In contrast, 5-HT induced secondary neurite outgrowth, an effect inhibited by 1 μM WAY-100635 or SB269970. These results suggest that both serotonergic receptors participate in secondary neurite outgrowth. We conclude that 5-HT1A R and 5-HT7 R regulate neuronal morphology in primary hippocampal cultures by promoting secondary neurite outgrowth.

  20. Assessment of the roles of serines 5.43(239) and 5.46(242) for binding and potency of agonist ligands at the human serotonin 5-HT2A receptor.

    PubMed

    Braden, Michael R; Nichols, David E

    2007-11-01

    We assessed the relative importance of two serine residues located near the top of transmembrane helix 5 of the human 5-HT(2A) receptor, comparing the wild type with S5.43(239)A or S5.46(242)A mutations. Using the ergoline lysergic acid diethylamide (LSD), and a series of substituted tryptamine and phenethylamine 5-HT(2A) receptor agonists, we found that Ser5.43(239) is more critical for agonist binding and function than Ser5.46(242). Ser5.43(239) seems to engage oxygen substituents at either the 4- or 5-position of tryptamine ligands and the 5-position of phenylalkylamine ligands. Even when a direct binding interaction cannot occur, our data suggest that Ser5.43(239) is still important for receptor activation. Polar ring-substituted tryptamine ligands also seem to engage Ser5.46(242), but tryptamines lacking such a substituent may adopt an alternate binding orientation that does not engage this residue. Our results are consistent with the role of Ser5.43(239) as a hydrogen bond donor, whereas Ser5.46(242) seems to serve as a hydrogen bond acceptor. These results are consistent with the functional topography and utility of our in silico-activated homology model of the h5-HT(2A) receptor. In addition, being more distal from the absolutely conserved Pro5.50, a strong interaction with Ser5.43(239) may be more effective in straightening the kink in helix 5, a feature that is possibly common to all type A GPCRs that have polar residues at position 5.43.

  1. Cerebral 5-HT release correlates with [(11)C]Cimbi36 PET measures of 5-HT2A receptor occupancy in the pig brain.

    PubMed

    Jørgensen, Louise M; Weikop, Pia; Villadsen, Jonas; Visnapuu, Tanel; Ettrup, Anders; Hansen, Hanne D; Baandrup, Anders O; Andersen, Flemming L; Bjarkam, Carsten R; Thomsen, Carsten; Jespersen, Bo; Knudsen, Gitte M

    2017-02-01

    Positron emission tomography (PET) can, when used with appropriate radioligands, non-invasively generate temporal and spatial information about acute changes in brain neurotransmitter systems. We for the first time evaluate the novel 5-HT2A receptor agonist PET radioligand, [(11)C]Cimbi-36, for its sensitivity to detect changes in endogenous cerebral 5-HT levels, as induced by different pharmacological challenges. To enable a direct translation of PET imaging data to changes in brain 5-HT levels, we calibrated the [(11)C]Cimbi-36 PET signal in the pig brain by simultaneous measurements of extracellular 5-HT levels with microdialysis and [(11)C]Cimbi-36 PET after various acute interventions (saline, citalopram, citalopram + pindolol, fenfluramine). In a subset of pigs, para-chlorophenylalanine pretreatment was given to deplete cerebral 5-HT. The interventions increased the cerebral extracellular 5-HT levels to 2-11 times baseline, with fenfluramine being the most potent pharmacological enhancer of 5-HT release, and induced a varying degree of decline in [(11)C]Cimbi-36 binding in the brain, consistent with the occupancy competition model. The observed correlation between changes in the extracellular 5-HT level in the pig brain and the 5-HT2A receptor occupancy indicates that [(11)C]Cimbi-36 binding is sensitive to changes in endogenous 5-HT levels, although only detectable with PET when the 5-HT release is sufficiently high.

  2. Molecular dynamics of 5-HT1A and 5-HT2A serotonin receptors with methylated buspirone analogues

    NASA Astrophysics Data System (ADS)

    Bronowska, Agnieszka; Chilmonczyk, Zdzisław; Leś, Andrzej; Edvardsen, Øyvind; Østensen, Roy; Sylte, Ingebrigt

    2001-11-01

    In the present study experimentally determined ligand selectivity of three methylated buspirone analogues (denoted as MM2, MM5 and P55) towards 5-HT1A and 5-HT2A serotonin receptors was theoretically investigated on a molecular level. The relationships between the ligand structure and 5-HT1A and 5-HT2A receptor affinities were studied and the results were found to be in agreement with the available site-directed mutagenesis and binding affinity data. Molecular dynamics (MD) simulations of ligand-receptor complexes were performed for each investigated analogue, docked twice into the central cavity of 5-HT1A/5-HT2A, each time in a different orientation. Present results were compared with our previous theoretical results, obtained for buspirone and its non-methylated analogues. It was found that due to the presence of the methyl group in the piperazine ring the ligand position alters and the structure of the ligand-receptor complex is modified. Further, the positions of derivatives with pyrimidinyl aromatic moiety and quinolinyl moiety are significantly different at the 5-HT2A receptor. Thus, methylation of such derivatives alters the 3D structures of ligand-receptor complexes in different ways. The ligand-induced changes of the receptor structures were also analysed. The obtained results suggest, that helical domains of both receptors have different dynamical behaviour. Moreover, both location and topography of putative binding sites for buspirone analogues are different at 5-HT1A and 5-HT2A receptors.

  3. Classification of 5-HT(1A) receptor ligands on the basis of their binding affinities by using PSO-Adaboost-SVM.

    PubMed

    Cheng, Zhengjun; Zhang, Yuntao; Zhou, Changhong; Zhang, Wenjun; Gao, Shibo

    2009-07-29

    In the present work, the support vector machine (SVM) and Adaboost-SVM have been used to develop a classification model as a potential screening mechanism for a novel series of 5-HT(1A) selective ligands. Each compound is represented by calculated structural descriptors that encode topological features. The particle swarm optimization (PSO) and the stepwise multiple linear regression (Stepwise-MLR) methods have been used to search descriptor space and select the descriptors which are responsible for the inhibitory activity of these compounds. The model containing seven descriptors found by Adaboost-SVM, has showed better predictive capability than the other models. The total accuracy in prediction for the training and test set is 100.0% and 95.0% for PSO-Adaboost-SVM, 99.1% and 92.5% for PSO-SVM, 99.1% and 82.5% for Stepwise-MLR-Adaboost-SVM, 99.1% and 77.5% for Stepwise-MLR-SVM, respectively. The results indicate that Adaboost-SVM can be used as a useful modeling tool for QSAR studies.

  4. Hippocampal 5-HT1A Receptor and Spatial Learning and Memory

    PubMed Central

    Glikmann-Johnston, Yifat; Saling, Michael M.; Reutens, David C.; Stout, Julie C.

    2015-01-01

    Spatial cognition is fundamental for survival in the topographically complex environments inhabited by humans and other animals. The hippocampus, which has a central role in spatial cognition, is characterized by high concentration of serotonin (5-hydroxytryptamine; 5-HT) receptor binding sites, particularly of the 1A receptor (5-HT1A) subtype. This review highlights converging evidence for the role of hippocampal 5-HT1A receptors in spatial learning and memory. We consider studies showing that activation or blockade of the 5-HT1A receptors using agonists or antagonists, respectively, lead to changes in spatial learning and memory. For example, pharmacological manipulation to induce 5-HT release, or to block 5-HT uptake, have indicated that increased extracellular 5-HT concentrations maintain or improve memory performance. In contrast, reduced levels of 5-HT have been shown to impair spatial memory. Furthermore, the lack of 5-HT1A receptor subtype in single gene knockout mice is specifically associated with spatial memory impairments. These findings, along with evidence from recent cognitive imaging studies using positron emission tomography (PET) with 5-HT1A receptor ligands, and studies of individual genetic variance in 5-HT1A receptor availability, strongly suggests that 5-HT, mediated by the 5-HT1A receptor subtype, plays a key role in spatial learning and memory. PMID:26696889

  5. 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

  6. 5-HT7 receptor activation inhibits mechanical hypersensitivity secondary to capsaicin sensitization in mice.

    PubMed

    Brenchat, Alex; Romero, Luz; García, Mónica; Pujol, Marta; Burgueño, Javier; Torrens, Antoni; Hamon, Michel; Baeyens, José Manuel; Buschmann, Helmut; Zamanillo, Daniel; Vela, José Miguel

    2009-02-01

    This work aimed to evaluate the potential role of the 5-HT(7) receptor in nociception secondary to a sensitizing stimulus in mice. For this purpose, the effects of relevant ligands (5-HT(7) receptor agonists: AS-19, MSD-5a, E-55888; 5-HT(7) receptor antagonists: SB-258719, SB-269970; 5-HT(1A) receptor agonist: F-13640; 5-HT(1A) receptor antagonist: WAY-100635) were assessed on capsaicin-induced mechanical hypersensitivity, a pain behavior involving hypersensitivity of dorsal horn neurons (central sensitization). For the 5-HT(7) receptor agonists used, binding profile and intrinsic efficacy to stimulate cAMP formation in HEK-293F cells expressing the human 5-HT(7) receptor were also evaluated. AS-19 and E-55888 were selective for 5-HT(7) receptors. E-55888 was a full agonist whereas AS-19 and MSD-5a behaved as partial agonists, with maximal effects corresponding to 77% and 61%, respectively, of the cAMP response evoked by the full agonist 5-HT. Our in vivo results revealed that systemic administration of 5-HT(7) receptor agonists exerted a clear-cut dose-dependent antinociceptive effect that was prevented by 5-HT(7) receptor antagonists, but not by the 5-HT(1A) receptor antagonist. The order of efficacy (E-55888>AS-19>MSD-5a) matched their in vitro efficacy as 5-HT(7) receptor agonists. Contrary to agonists, a dose-dependent promotion of mechanical hypersensitivity was observed after administration of 5-HT(7) receptor antagonists, substantiating the involvement of the 5-HT(7) receptor in the control of capsaicin-induced mechanical hypersensitivity. These findings suggest that serotonin exerts an inhibitory role in the control of nociception through activation of 5-HT(7) receptors, and point to a new potential therapeutic use of 5-HT(7) receptor agonists in the field of analgesia.

  7. 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.

  8. Serotonin and psychostimulant addiction: focus on 5-HT1A-receptors.

    PubMed

    Müller, Christian P; Carey, Robert J; Huston, Joseph P; De Souza Silva, Maria A

    2007-02-01

    Serotonin(1A)-receptors (5-HT(1A)-Rs) are important components of the 5-HT system in the brain. As somatodendritic autoreceptors they control the activity of 5-HT neurons, and, as postsynaptic receptors, the activity in terminal areas. Cocaine (COC), amphetamine (AMPH), methamphetamine (METH) and 3,4-methylenedioxymethamphetamine ("Ecstasy", MDMA) are psychostimulant drugs that can lead to addiction-related behavior in humans and in animals. At the neurochemical level, these psychostimulant drugs interact with monoamine transporters and increase extracellular 5-HT, dopamine and noradrenalin activity in the brain. The increase in 5-HT, which, in addition to dopamine, is a core mechanism of action for drug addiction, hyperactivates 5-HT(1A)-Rs. Here, we first review the role of the various 5-HT(1A)-R populations in spontaneous behavior to provide a background to elucidate the contribution of the 5-HT(1A)-Rs to the organization of psychostimulant-induced addiction behavior. The progress achieved in this field shows the fundamental contribution of brain 5-HT(1A)-Rs to virtually all behaviors associated with psychostimulant addiction. Importantly, the contribution of pre- and postsynaptic 5-HT(1A)-Rs can be dissociated and frequently act in opposite directions. We conclude that 5-HT(1A)-autoreceptors mainly facilitate psychostimulant addiction-related behaviors by a limitation of the 5-HT response in terminal areas. Postsynaptic 5-HT(1A)-Rs, in contrast, predominantly inhibit the expression of various addiction-related behaviors directly. In addition, they may also influence the local 5-HT response by feedback mechanisms. The reviewed findings do not only show a crucial role of 5-HT(1A)-Rs in the control of brain 5-HT activity and spontaneous behavior, but also their complex role in the regulation of the psychostimulant-induced 5-HT response and subsequent addiction-related behaviors.

  9. Deletion of Munc18-1 in 5-HT Neurons Results in Rapid Degeneration of the 5-HT System and Early Postnatal Lethality

    PubMed Central

    Dudok, Jacobus J.; Groffen, Alexander J. A.; Toonen, Ruud F. T.; Verhage, Matthijs

    2011-01-01

    The serotonin (5-HT) system densely innervates many brain areas and is important for proper brain development. To specifically ablate the 5-HT system we generated mutant mice carrying a floxed Munc18-1 gene and Cre recombinase driven by the 5-HT-specific serotonin reuptake transporter (SERT) promoter. The majority of mutant mice died within a few days after birth. Immunohistochemical analysis of brains of these mice showed that initially 5-HT neurons are formed and the cortex is innervated with 5-HT projections. From embryonic day 16 onwards, however, 5-HT neurons started to degenerate and at postnatal day 2 hardly any 5-HT projections were present in the cortex. The 5-HT system of mice heterozygous for the floxed Munc18-1 allele was indistinguishable from control mice. These data show that deletion of Munc18-1 in 5-HT neurons results in rapid degeneration of the 5-HT system and suggests that the 5-HT system is important for postnatal survival. PMID:22140524

  10. The 5-HT1-like receptor mediating the increase in canine external carotid blood flow: close resemblance to the 5-HT1D subtype.

    PubMed Central

    Villalón, C M; Terrón, J A

    1994-01-01

    1. It has recently been shown that the increase in external carotid blood flow induced by 5-hydroxy-tryptamine (5-HT) in the anaesthetized dog, being mimicked by 5-carboxamidotryptamine (5-CT), inhibited by methiothepin, vagosympathectomy and sympatho-inhibitory drugs, and resistant to blockade by ritanserin and MDL 72222, is mediated by stimulation of prejunctional 5-HT1-like receptors leading to an inhibitory action on carotid sympathetic nerves; these 5-HT1-like receptors are unrelated to either the 5-HT1A, 5-HT1B or 5-HT1C (now 5-HT2C) receptor subtypes. Inasmuch as 5-CT, 5-methoxytryptamine, sumatriptan and metergoline display high affinity, amongst other 5-HT binding sites, for the 5-HT1D subtype, in the present study we have used these drugs in an attempt to determine whether the above inhibitory prejunctional 5-HT1-like receptors correlate with the 5-HT1D subtype. 2. One-minute intracarotid (i.c.) infusions of 5-HT (0.3, 1, 3 and 10 micrograms), 5-CT (0.01, 0.03, 0.1 and 0.3 micrograms), 5-methoxytryptamine (1, 3, 10 and 30 micrograms) and sumatriptan (1, 3, 10, 30 and 100 micrograms) resulted in dose-dependent increases in external carotid blood flow (without changes in mean arterial blood pressure or heart rate) with the following rank order of agonist potency: 5-CT >> 5-HT > 5-methoxytryptamine > or = sumatriptan. Interestingly, sumatriptan-induced vasodilatation was followed by a more pronounced vasoconstriction. 3. The external carotid vasodilator effects of 5-HT, 5-CT, 5-methoxytryptamine and sumatriptan were dose-dependently and specifically antagonized by metergoline (10, 30 and/or 100 micrograms kg-1, i.v.).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7812603

  11. Selective siRNA-mediated suppression of 5-HT1A autoreceptors evokes strong anti-depressant-like effects.

    PubMed

    Bortolozzi, A; Castañé, A; Semakova, J; Santana, N; Alvarado, G; Cortés, R; Ferrés-Coy, A; Fernández, G; Carmona, M C; Toth, M; Perales, J C; Montefeltro, A; Artigas, F

    2012-06-01

    Depression is a major health problem worldwide. Most prescribed anti-depressants, the selective serotonin reuptake inhibitors (SSRI) show limited efficacy and delayed onset of action, partly due to the activation of somatodendritic 5-HT(1A)-autoreceptors by the excess extracellular serotonin (5-HT) produced by SSRI in the raphe nuclei. Likewise, 5-HT(1A) receptor (5-HT(1A)R) gene polymorphisms leading to high 5-HT(1A)-autoreceptor expression increase depression susceptibility and decrease treatment response. In this study, we report on a new treatment strategy based on the administration of small-interfering RNA (siRNA) to acutely suppress 5-HT(1A)-autoreceptor-mediated negative feedback mechanisms. We developed a conjugated siRNA (C-1A-siRNA) by covalently binding siRNA targeting 5-HT(1A) receptor mRNA with the SSRI sertraline in order to concentrate it in serotonin axons, rich in serotonin transporter (SERT) sites. The intracerebroventricular (i.c.v.) infusion of C-1A-siRNA to mice resulted in its selective accumulation in serotonin neurons. This evoked marked anti-depressant-like effects in the forced swim and tail suspension tests, but did not affect anxiety-like behaviors in the elevated plus-maze. In parallel, C-1A-siRNA administration markedly decreased 5-HT(1A)-autoreceptor expression and suppressed 8-OH-DPAT-induced hypothermia (a pre-synaptic 5-HT(1A)R effect in mice) without affecting post-synaptic 5-HT(1A)R expression in hippocampus and prefrontal cortex. Moreover, i.c.v. C-1A-siRNA infusion augmented the increase in extracellular serotonin evoked by fluoxetine in prefrontal cortex to the level seen in 5-HT(1A)R knockout mice. Interestingly, intranasal C-1A-siRNA administration produced the same effects, thus opening the way to the therapeutic use of C-1A-siRNA. Hence, C-1A-siRNA represents a new approach to treat mood disorders as monotherapy or in combination with SSRI.

  12. Menthol inhibits 5-HT3 receptor-mediated currents.

    PubMed

    Ashoor, Abrar; Nordman, Jacob C; Veltri, Daniel; Yang, Keun-Hang Susan; Shuba, Yaroslav; Al Kury, Lina; Sadek, Bassem; Howarth, Frank C; Shehu, Amarda; Kabbani, Nadine; Oz, Murat

    2013-11-01

    The effects of alcohol monoterpene menthol, a major active ingredient of the peppermint plant, were tested on the function of human 5-hydroxytryptamine type 3 (5-HT3) receptors expressed in Xenopus laevis oocytes. 5-HT (1 μM)-evoked currents recorded by two-electrode voltage-clamp technique were reversibly inhibited by menthol in a concentration-dependent (IC50 = 163 μM) manner. The effects of menthol developed gradually, reaching a steady-state level within 10-15 minutes and did not involve G-proteins, since GTPγS activity remained unaltered and the effect of menthol was not sensitive to pertussis toxin pretreatment. The actions of menthol were not stereoselective as (-), (+), and racemic menthol inhibited 5-HT3 receptor-mediated currents to the same extent. Menthol inhibition was not altered by intracellular 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid injections and transmembrane potential changes. The maximum inhibition observed for menthol was not reversed by increasing concentrations of 5-HT. Furthermore, specific binding of the 5-HT3 antagonist [(3)H]GR65630 was not altered in the presence of menthol (up to 1 mM), indicating that menthol acts as a noncompetitive antagonist of the 5-HT3 receptor. Finally, 5-HT3 receptor-mediated currents in acutely dissociated nodose ganglion neurons were also inhibited by menthol (100 μM). These data demonstrate that menthol, at pharmacologically relevant concentrations, is an allosteric inhibitor of 5-HT3 receptors.

  13. 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.

  14. 5-HT systems: emergent targets for memory formation and memory alterations.

    PubMed

    Meneses, Alfredo

    2013-01-01

    Drugs acting through 5-hydroxytryptamine (serotonin or 5-HT) systems modulate memory and its alterations, although the mechanisms involved are poorly understood. 5-HT drugs may present promnesic and/or antiamnesic (or even being amnesic) effects. Key questions regarding 5-HT markers include whether receptors directly or indirectly participate and/or contribute to the physiological and pharmacological basis of memory and its pathogenesis; hence, the major aim of this article was to examine recent advances in emergent targets of the 5-HT systems for memory formation and memory alterations. Recent reviews and findings are summarized, mainly in the context of the growing notion of memory deficits in brain disorders (e.g., posttraumatic stress disorder, mild cognitive impairment, consumption of drugs, poststroke cognitive dysfunctions, schizophrenia, Parkinson disease, and infection-induced memory impairments). Mainly, mammalian and (some) human data were the focus. At least agonists and antagonists for 5-HT1A/1B, 5-HT2A/2B/2C, 5-HT3, 5-HT4, 5-HT6, and 5-HT7 receptors as well as serotonin uptake inhibitors seem to have a promnesic and/or antiamnesic effect in different conditions and 5-HT markers seem to be associated to neural changes. Available evidence offers clues about the possibilities, but the exact mechanisms remain unclear. For instance, 5-HT transporter expression seems to be a reliable neural marker related to memory mechanisms and its alterations.

  15. Structure-activity relationships of quinoxaline-based 5-HT3A and 5-HT3AB receptor-selective ligands.

    PubMed

    Thompson, Andrew J; Verheij, Mark H P; van Muijlwijk-Koezen, Jacqueline E; Lummis, Sarah C R; Leurs, Rob; de Esch, Iwan J P

    2013-06-01

    Until recently, discriminating between homomeric 5-HT3A and heteromeric 5-HT3AB receptors was only possible with ligands that bind in the receptor pore. This study describes the first series of ligands that can discriminate between these receptor types at the level of the orthosteric binding site. During a recent fragment screen, 2-chloro-3-(4-methylpiperazin-1-yl)quinoxaline (VUF10166) was identified as a ligand that displays an 83-fold difference in [(3)H]granisetron binding affinity between 5-HT3A and 5-HT3AB receptors. Fragment hit exploration, initiated from VUF10166 and 3-(4-methylpiperazin-1-yl)quinoxalin-2-ol, resulted in a series of compounds with higher affinity at either 5-HT3A or 5-HT3AB receptors. These ligands reveal that a single atom is sufficient to change the selectivity profile of a compound. At the extremes of the new compounds were 2-amino-3-(4-methylpiperazin-1-yl)quinoxaline, which showed 11-fold selectivity for the 5-HT3A receptor, and 2-(4-methylpiperazin-1-yl)quinoxaline, which showed an 8.3-fold selectivity for the 5-HT3AB receptor. These compounds represent novel molecular tools for studying 5-HT3 receptor subtypes and could help elucidate their physiological roles.

  16. Functions of 5-HT2A receptor and its antagonists in the cardiovascular system.

    PubMed

    Nagatomo, Takafumi; Rashid, Mamunur; Abul Muntasir, Habib; Komiyama, Tadazumi

    2004-10-01

    The serotonin (5-hydroxytryptamine, 5-HT) receptors have conventionally been divided into seven subfamilies, most of which have several subtypes. Among them, 5-HT(2A) receptor is associated with the contraction of vascular smooth muscle, platelet aggregation and thrombus formation and coronary artery spasms. Accordingly, selective 5-HT(2A) antagonists may have potential in the treatment of cardiovascular diseases. Sarpogrelate, a selective 5-HT(2A) antagonist, has been introduced clinically as a therapeutic agent for the treatment of ischemic diseases associated with thrombosis. Molecular modeling studies also suggest that sarpogrelate is a 5-HT(2A) selective antagonist and is likely to have pharmacological effects beneficial in the treatment of cardiovascular diseases. This review describes the above findings as well as the signaling linkages of the 5-HT(2A) receptors and the mode of agonist binding to 5-HT(2A) receptor using data derived from molecular modeling and site-directed mutagenesis.

  17. Pharmacological Characterization of a 5-HT1-Type Serotonin Receptor in the Red Flour Beetle, Tribolium castaneum

    PubMed Central

    Vleugels, Rut; Lenaerts, Cynthia; Baumann, Arnd; Vanden Broeck, Jozef; Verlinden, Heleen

    2013-01-01

    Serotonin (5-hydroxytryptamine, 5-HT) is known for its key role in modulating diverse physiological processes and behaviors by binding various 5-HT receptors. However, a lack of pharmacological knowledge impedes studies on invertebrate 5-HT receptors. Moreover, pharmacological information is urgently needed in order to establish a reliable classification system for invertebrate 5-HT receptors. In this study we report on the molecular cloning and pharmacological characterization of a 5-HT1 receptor from the red flour beetle, Tribolium castaneum (Trica5-HT1). The Trica5-HT1 receptor encoding cDNA shows considerable sequence similarity with members of the 5-HT1 receptor class. Real time PCR showed high expression in the brain (without optic lobes) and the optic lobes, consistent with the role of 5-HT as neurotransmitter. Activation of Trica5-HT1 in mammalian cells decreased NKH-477-stimulated cyclic AMP levels in a dose-dependent manner, but did not influence intracellular Ca2+ signaling. We studied the pharmacological profile of the 5-HT1 receptor and demonstrated that α-methylserotonin, 5-methoxytryptamine and 5-carboxamidotryptamine acted as agonists. Prazosin, methiothepin and methysergide were the most potent antagonists and showed competitive inhibition in presence of 5-HT. This study offers important information on a 5-HT1 receptor from T. castaneum facilitating functional research of 5-HT receptors in insects and other invertebrates. The pharmacological profiles may contribute to establish a reliable classification scheme for invertebrate 5-HT receptors. PMID:23741451

  18. Lamotrigine, an antiepileptic drug, inhibits 5-HT3 receptor currents in NCB-20 neuroblastoma cells

    PubMed Central

    Kim, Ki Jung; Jeun, Seung Hyun

    2017-01-01

    Lamotrigine is an antiepileptic drug widely used to treat epileptic seizures. Using whole-cell voltage clamp recordings in combination with a fast drug application approach, we investigated the effects of lamotrigine on 5-hydroxytryptamine (5-HT)3 receptors in NCB-20 neuroblastoma cells. Co-application of lamotrigine (1~300 µM) resulted in a concentration-dependent reduction in peak amplitude of currents induced by 3 µM of 5-HT for an IC50 value of 28.2±3.6 µM with a Hill coefficient of 1.2±0.1. These peak amplitude decreases were accompanied by the rise slope reduction. In addition, 5-HT3-mediated currents evoked by 1 mM dopamine, a partial 5-HT3 receptor agonist, were inhibited by lamotrigine co-application. The EC50 of 5-HT for 5-HT3 receptor currents were shifted to the right by co-application of lamotrigine without a significant change of maximal effect. Currents activated by 5-HT and lamotrigine co-application in the presence of 1 min pretreatment of lamotrigine were similar to those activated by 5-HT and lamotrigine co-application alone. Moreover, subsequent application of lamotrigine in the presence of 5-HT and 5-hydroxyindole, known to attenuate 5-HT3 receptor desensitization, inhibited 5-HT3 receptor currents in a concentration-dependent manner. The deactivation of 5-HT3 receptor was delayed by washing with an external solution containing lamotrigine. Lamotrigine accelerated the desensitization process of 5-HT3 receptors. There was no voltage-dependency in the inhibitory effects of lamotrigine on the 5-HT3 receptor currents. These results indicate that lamotrigine inhibits 5-HT3-activated currents in a competitive manner by binding to the open state of the channels and blocking channel activation or accelerating receptor desensitization. PMID:28280410

  19. Lamotrigine, an antiepileptic drug, inhibits 5-HT3 receptor currents in NCB-20 neuroblastoma cells.

    PubMed

    Kim, Ki Jung; Jeun, Seung Hyun; Sung, Ki-Wug

    2017-03-01

    Lamotrigine is an antiepileptic drug widely used to treat epileptic seizures. Using whole-cell voltage clamp recordings in combination with a fast drug application approach, we investigated the effects of lamotrigine on 5-hydroxytryptamine (5-HT)3 receptors in NCB-20 neuroblastoma cells. Co-application of lamotrigine (1~300 µM) resulted in a concentration-dependent reduction in peak amplitude of currents induced by 3 µM of 5-HT for an IC50 value of 28.2±3.6 µM with a Hill coefficient of 1.2±0.1. These peak amplitude decreases were accompanied by the rise slope reduction. In addition, 5-HT3-mediated currents evoked by 1 mM dopamine, a partial 5-HT3 receptor agonist, were inhibited by lamotrigine co-application. The EC50 of 5-HT for 5-HT3 receptor currents were shifted to the right by co-application of lamotrigine without a significant change of maximal effect. Currents activated by 5-HT and lamotrigine co-application in the presence of 1 min pretreatment of lamotrigine were similar to those activated by 5-HT and lamotrigine co-application alone. Moreover, subsequent application of lamotrigine in the presence of 5-HT and 5-hydroxyindole, known to attenuate 5-HT3 receptor desensitization, inhibited 5-HT3 receptor currents in a concentration-dependent manner. The deactivation of 5-HT3 receptor was delayed by washing with an external solution containing lamotrigine. Lamotrigine accelerated the desensitization process of 5-HT3 receptors. There was no voltage-dependency in the inhibitory effects of lamotrigine on the 5-HT3 receptor currents. These results indicate that lamotrigine inhibits 5-HT3-activated currents in a competitive manner by binding to the open state of the channels and blocking channel activation or accelerating receptor desensitization.

  20. 5-HT 1A/1B receptor-mediated effects of the selective serotonin reuptake inhibitor, citalopram, on sleep: studies in 5-HT 1A and 5-HT 1B knockout mice.

    PubMed

    Monaca, Christelle; Boutrel, Benjamin; Hen, René; Hamon, Michel; Adrien, Joëlle

    2003-05-01

    Selective serotonin reuptake inhibitors (SSRIs) are extensively used for the treatment of depression. Aside from their antidepressant properties, they provoke a deficit in paradoxical sleep (PS) that is most probably mediated by the transporter blockade-induced increase in serotonin concentration in the extracellular space. Such an effect can be accounted for by the action of serotonin at various types of serotonergic receptors involved in PS regulation, among which the 5-HT(1A) and 5-HT(1B) types are the best candidates. According to this hypothesis, we examined the effects of citalopram, the most selective SSRI available to date, on sleep in the mouse after inactivation of 5-HT(1A) or 5-HT(1B) receptors, either by homologous recombination of their encoding genes, or pharmacological blockade with selective antagonists. For this purpose, sleep parameters of knockout mice that do not express these receptors and their wild-type counterparts were monitored during 8 h after injection of citalopram alone or in association with 5-HT(1A) or 5-HT(1B) receptor antagonists. Citalopram induced mainly a dose-dependent inhibition of PS during 2-6 h after injection, which was observed in wild-type and 5-HT(1B)-/- mice, but not in 5-HT(1A)-/- mutants. This PS inhibition was fully antagonized by pretreatment with the 5-HT(1A) antagonist WAY 100635, but only partially with the 5-HT(1B) antagonist GR 127935. These data indicate that the action of the SSRI citalopram on sleep in the mouse is essentially mediated by 5-HT(1A) receptors. Such a mechanism of action provides further support to the clinical strategy of antidepressant augmentation by 5-HT(1A) antagonists, because the latter would also counteract the direct sleep-inhibitory side-effects of SSRIs.

  1. Effects of Constant Flickering Light on Refractive Status, 5-HT and 5-HT2A Receptor in Guinea Pigs

    PubMed Central

    Li, Tao; Zheng, Changyue; Ji, Shunmei; Ma, Yuanyuan; Zhang, Shuangshuang; Zhou, Xiaodong

    2016-01-01

    light could cause progressive myopia in guinea pigs. 5-HT and 5-HT2A receptor increased both in form deprivation myopia and flickering light induced myopia, indicating that 5-HT possibly involved in myopic development via binding to5-HT2A receptor. PMID:27959948

  2. Electroacupuncture Restores 5-HT System Deficit in Chronic Mild Stress-Induced Depressed Rats

    PubMed Central

    Tu, Ya; Yang, Xiuyan; Liu, Ping

    2016-01-01

    Objective. The current study is designed to investigate the antidepressant efficacy of electroacupuncture (EA) treatment by evaluating its effect on the synthesis, metabolism, reuptake, and receptors of 5-hydroxytryptamine (5-HT), so as to clarify the molecular mechanisms of EA for antidepression. Materials and Methods. Solitary combined with the chronic unpredictable mild stress (CUMS) was used to establish the rat model with depression. The depressed rats were supplied with EA treatment for 4 weeks, and the behavior change and the following indices including 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), monoamine oxidase A (MAO-A), tryptophan hydroxylase (TPH), 5-HT transporter (SERT), 5-HT1A, and 5-HT2A in hippocampus and prefrontal cortex were examined. Results. EA treatment significantly improved the behavior of rats and increased 5-HT level in hippocampus of depressed rats. Similarly, EA treatment could significantly increase protein and mRNA expression of TPH and 5-HT1A during 5-HT synthesis process in hippocampus of depressed rats. However, EA treatment had no effect on the activity of MAO-A and the expression of SERT protein and mRNA. Conclusion. Antidepressant efficacy of EA treatment can be accomplished through enhancing 5-HT synthesis, upregulating 5-HT1A level, and improving 5-HT content in brain and synaptic gaps. PMID:27994633

  3. Guinea pig hippocampal 5-HT(1E) receptors: a tool for selective drug development.

    PubMed

    Klein, Michael T; Teitler, Milt

    2009-04-01

    Recent studies have indicated that the serotonin [5-hydroxytryptamine (5-HT)] 1E receptor, originally discovered in human brain tissue, is not expressed in rat or mouse brain. Thus, there have been few reports on 5-HT(1E) receptor drug development. However, expression of 5-HT(1E) receptor mRNA has been shown in guinea pig brain. To establish this species as an animal model for 5-HT(1E) drug development, we identified brain regions that exhibit 5-carboxyamidotryptamine, ritanserin, and LY344864 - insensitive [(3)H]5-HT binding (characteristic of the 5-HT(1E) receptor). In hippocampal homogenates, where 5-HT(1E) receptor density was sufficiently high for radioligand binding analysis, 100 nM 5-carboxyamidotryptamine, 30 nM ritanserin, and 100 nM LY344864 were used to mask [(3)H]5-HT binding at non-5-HT(1E) receptors. The K(d) of [(3)H]5-HT was 5.7 +/- 0.7 nM and is indistinguishable from the cloned receptor K(d) of 6.5 +/- 0.6 nM. The affinities of 16 drugs for the cloned and hippocampal-expressed guinea pig 5-HT(1E) receptors are essentially identical (R(2) = 0.97). These findings indicate that using these conditions autoradiographical distribution and signal transduction studies of the 5-HT(1E) receptor in guinea pig brain are feasible. Using the guinea pig as an animal model should provide important insights into possible functions of this receptor and the therapeutic potential of selective human 5-HT(1E) drugs.

  4. Allosteric modulation of the effects of the 5-HT reuptake inhibitor escitalopram on the rat hippocampal synaptic plasticity.

    PubMed

    Mnie-Filali, Ouissame; El Mansari, Mostafa; Espana, Agnès; Sànchez, Connie; Haddjeri, Nasser

    2006-02-27

    The present in vivo electrophysiological studies in anesthetized rat were undertaken to assess the effects of the selective serotonin (5-HT) reuptake inhibitor (SSRI) escitalopram alone or in combination with the R-citalopram (the S- and R-enantiomers of citalopram), on both long-term potentiation (LTP) in the CA(1) region of dorsal hippocampus and spontaneous firing activity of dorsal raphe (DR) 5-HT neurons. At the postsynaptic level, neither escitalopram (10 mg/kg, i.p.) nor R-citalopram (20 mg/kg, i.p.) modified basal synaptic transmission but only escitalopram impaired LTP expression. Importantly, R-citalopram counteracted significantly the escitalopram-induced decrease of LTP. At the pre-synaptic level, escitalopram (25-75 microg/kg, i.v.) dose-dependently suppressed the spontaneous firing activity of DR 5-HT neurons and this suppressant effect was significantly prevented by a prior injection of R-citalopram (10 mg/kg, i.p.). These results support a role of allosteric binding sites of 5-HT transporter in the regulation of long-lasting CA(1) synaptic plasticity and DR 5-HT neuronal firing activity.

  5. Control of Amygdala Circuits by 5-HT Neurons via 5-HT and Glutamate Cotransmission

    PubMed Central

    Bannerman, David M.

    2017-01-01

    The serotonin (5-HT) system and the amygdala are key regulators of emotional behavior. Several lines of evidence suggest that 5-HT transmission in the amygdala is implicated in the susceptibility and drug treatment of mood disorders. Therefore, elucidating the physiological mechanisms through which midbrain 5-HT neurons modulate amygdala circuits could be pivotal in understanding emotional regulation in health and disease. To shed light on these mechanisms, we performed patch-clamp recordings from basal amygdala (BA) neurons in brain slices from mice with channelrhodopsin genetically targeted to 5-HT neurons. Optical stimulation of 5-HT terminals at low frequencies (≤1 Hz) evoked a short-latency excitation of BA interneurons (INs) that was depressed at higher frequencies. Pharmacological analysis revealed that this effect was mediated by glutamate and not 5-HT because it was abolished by ionotropic glutamate receptor antagonists. Optical stimulation of 5-HT terminals at higher frequencies (10–20 Hz) evoked both slow excitation and slow inhibition of INs. These effects were mediated by 5-HT because they were blocked by antagonists of 5-HT2A and 5-HT1A receptors, respectively. These fast glutamate- and slow 5-HT-mediated responses often coexisted in the same neuron. Interestingly, fast-spiking and non-fast-spiking INs displayed differential modulation by glutamate and 5-HT. Furthermore, optical stimulation of 5-HT terminals did not evoke glutamate release onto BA principal neurons, but inhibited these cells directly via activation of 5-HT1A receptors and indirectly via enhanced GABA release. Collectively, these findings suggest that 5-HT neurons exert a frequency-dependent, cell-type-specific control over BA circuitry via 5-HT and glutamate co-release to inhibit the BA output. SIGNIFICANCE STATEMENT The modulation of the amygdala by serotonin (5-HT) is important for emotional regulation and is implicated in the pathogenesis and treatment of affective disorders

  6. Rabies virus selectively alters 5-HT1 receptor subtypes in rat brain.

    PubMed

    Ceccaldi, P E; Fillion, M P; Ermine, A; Tsiang, H; Fillion, G

    1993-04-15

    Rabies virus infection in man induces a series of clinical symptoms, some suggesting involvement of the central serotonergic system. The results of the present study show that, 5 days after rabies virus infection in rat, the total reversible high-affinity binding of [3H]5-HT in the hippocampus is not affected, suggesting that 5-HT1A binding is not altered. 5-HT1B sites identified by [125I]cyanopindolol binding are not affected in the cortex 3 and 5 days after the infection. Accordingly, the cellular inhibitory effect of trifluoromethylphenylpiperazine (TFMPP) on the [3H]acetylcholine-evoked release, presumably related to 5-HT1B receptor activity, is not modified 3 days after infection. In contrast, [3H]5-HT binding determined in the presence of drugs masking 5-HT1A, 5-HT1B and 5-HT1C receptors, is markedly (50%) reduced 3 days after the viral infection. These results suggest that 5-HT1D-like receptor subtypes may be affected specifically and at an early stage after rabies viral infection.

  7. Uptake of taurine, GABA, 5-HT, and dopamine by blood platelets in progressive myoclonus epilepsy.

    PubMed

    Airaksinen, E M

    1979-10-01

    The uptakes of four neurotransmitters (taurine, GABA, 5-HT, and dopamine) by blood platelets from patients with degenerative-type progressive myoclonus epilepsy (PME) and from controls were studied using different incubation times and different concentrations. Only the uptakes of taurine differed significantly between patients and controls: patients' uptakes were 70% to 80% of control values at 10, 30, 60, and 120 min of incubation time. Km values were approximately the same, but Vmax values in PME patients were lower, showing quantitative but not qualitative differences in taurine uptake by platelets in PME. These results suggest that a defect or an inhibitory mechanism of some factor needed in the transport or binding of taurine (but not of GABA, 5-HT, and dopamine) is present in PME.

  8. 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

    2014-01-03

    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.

  9. Polysynaptic excitatory postsynaptic potentials that trigger spasms after spinal cord injury in rats are inhibited by 5-HT1B and 5-HT1F receptors.

    PubMed

    Murray, Katherine C; Stephens, Marilee J; Rank, Michelle; D'Amico, Jessica; Gorassini, Monica A; Bennett, David J

    2011-08-01

    Sensory afferent transmission and associated spinal reflexes are normally inhibited by serotonin (5-HT) derived from the brain stem. Spinal cord injury (SCI) that eliminates this 5-HT innervation leads to a disinhibition of sensory transmission and a consequent emergence of unusually long polysynaptic excitatory postsynaptic potentials (EPSPs) in motoneurons. These EPSPs play a critical role in triggering long polysynaptic reflexes (LPRs) that initiate muscles spasms. In the present study we examined which 5-HT receptors modulate the EPSPs and whether these receptors adapt to a loss of 5-HT after chronic spinal transection in rats. The EPSPs and associated LPRs recorded in vitro in spinal cords from chronic spinal rats were consistently inhibited by 5-HT(1B) or 5-HT(1F) receptor agonists, including zolmitriptan (5-HT(1B/1D/1F)) and LY344864 (5-HT(1F)), with a sigmoidal dose-response relation, from which we computed the 50% inhibition (EC(50)) and potency (-log EC(50)). The potencies of 5-HT receptor agonists were highly correlated with their binding affinity to 5-HT(1B) and 5-HT(1F) receptors, and not to other 5-HT receptors. Zolmitriptan also inhibited the LPRs and general muscle spasms recorded in vivo in the awake chronic spinal rat. The 5-HT(1B) receptor antagonists SB216641 and GR127935 and the inverse agonist SB224289 reduced the inhibition of LPRs by 5-HT(1B) agonists (zolmitriptan). However, when applied alone, SB224289, SB216641, and GR127935 had no effect on the LPRs, indicating that 5-HT(1B) receptors do not adapt to chronic injury, remaining silent, without constitutive activity. The reduction in EPSPs with zolmitriptan unmasked a large glycine-mediated inhibitory postsynaptic current (IPSC) after SCI. This IPSC and associated chloride current reversed at -73 mV, slightly below the resting membrane potential. Zolmitriptan did not change motoneuron properties. Our results demonstrate that 5-HT(1B/1F) agonists, such as zolmitriptan, can restore inhibition

  10. The interaction of trichloroethanol with murine recombinant 5-HT3 receptors.

    PubMed Central

    Downie, D L; Hope, A G; Belelli, D; Lambert, J J; Peters, J A; Bentley, K R; Steward, L J; Chen, C Y; Barnes, N M

    1995-01-01

    1. The effects of ethanol, chloral hydrate and trichloroethanol upon the 5-HT3 receptor have been investigated by use of electrophysiological techniques applied to recombinant 5-HT3 receptor subunits (5-HT3R-A or 5-HT3R-As) expressed in Xenopus laevis oocytes. Additionally, the influence of trichloroethanol upon the specific binding of [3H]-granisetron to membrane preparations of HEK 293 cells stably transfected with the murine 5-HT3R-As subunit and 5-HT3 receptors endogenous to NG 108-15 cell membranes was assessed. 2. Ethanol (30-300 mM), chloral hydrate (1-30 mM) and trichloroethanol (0.3-10 mM), produced a reversible, concentration-dependent, enhancement of 5-HT-mediated currents recorded from oocytes expressing either the 5-HT3R-A, or the 5-HT3R-As subunit. 3. Trichloroethanol (5 mM) produced a parallel leftward shift of the 5-HT concentration-response curve, reducing the EC50 for 5-HT from 1 +/- 0.04 microM (n = 4) to 0.5 +/- 0.01 microM (n = 4) for oocytes expressing the 5-HT3R-A. A similar shift, from 2.1 +/- 0.05 microM (n = 11) to 1.3 +/- 0.1 microM (n = 4), was observed in oocytes expressing the 5-HT3R-As subunit. Trichloroethanol (5 mM) had little or no effect upon the maximum current produced by 5-HT for either recombinant receptor. 4. Trichloroethanol (5 mM) similarly reduced the EC50 for 2-methyl-5-HT from 13 +/- 0.4 microM (n = 4) to 4.6 +/- 0.2 microM (n = 4) and from 15 +/- 2 microM (n = 4) to 5 +/- 0.4 microM (n = 4) for oocytes expressing the 5-HT3R-A and 5-HT3R-As subunit respectively. Additionally, trichloroethanol (5 mM) produced a clear enhancement of the maximal current to 2-methyl-5-HT (expressed as a percentage of the maximal current to 5-HT) from 63 +/- 0.7% (n = 4) to 101 +/- 1.6% (n = 4) and from 9 +/- 0.2% (n = 4) to 74 +/- 2% (n = 4) for oocytes expressing the 5-HT3R-A and 5-HT3R-As subunit respectively. 5. Trichloroethanol (2.5 mM) had no effect upon the Kd, or Bmax, of specific [3H]-granisetron binding to membrane homogenates of NG

  11. Differential classification of vascular smooth muscle and endothelial cell 5-HT receptors by use of tryptamine analogues.

    PubMed Central

    Leff, P.; Martin, G. R.; Morse, J. M.

    1987-01-01

    In ring preparations of the rabbit external jugular vein contracted with the thromboxane-mimetic U-46619, submicromolar concentrations of 5-hydroxytryptamine (5-HT) and chemically related analogues produced relaxations that were dependent on the integrity of the vascular endothelium. The receptor mediating endothelium-dependent relaxations was evidently similar to previously described endothelial 5-HT receptors since relaxation responses to alpha-methyl-5-HT were not blocked by atropine, (+/-)-propranolol, yohimbine, indomethacin, ketanserin or MDL-72222, but were non-competitively antagonized by methysergide, methiothepin and cyproheptadine. The activities of some tryptamine agonists and antagonists at the endothelial 5-HT receptor in rabbit jugular vein were compared with their activities at the smooth muscle 5-HT2-receptor in rabbit aortic rings. Differences in the tryptamines' affinities and relative efficacies showed that the endothelial 5-HT receptor was not of the 5-HT2-type. The high agonist potencies of 5-HT and 5-carboxamidotryptamine, the susceptibility to antagonism by both methiothepin and methysergide and the resistance to blockade by selective 5-HT2 and 5-HT3 ('M') receptor antagonists implies that the endothelial receptor belongs to the '5-HT1-like' class. However, the agonist potency order 5-HT = alpha-methyl-5-HT greater than 5-carboxamidotryptamine suggested that the receptor is not the same as the peripheral '5-HT1-like' receptors reported to mediate directly contraction of the dog saphenous vein or relaxation of vascular and non-vascular smooth muscles. At these receptors, the potency order is 5-carboxamidotryptamine greater than 5-HT greater than alpha-methyl-5-HT. These results constitute preliminary evidence that peripheral '5-HT1-like' receptors, like central 5-HT1 recognition sites, are a heterogeneous population. Further comparative studies with a wider range of receptor probes are necessary to establish whether or not these receptors

  12. Involvement of 5-HT3 receptors in the action of vortioxetine in rat brain: Focus on glutamatergic and GABAergic neurotransmission.

    PubMed

    Riga, Maurizio S; Sánchez, Connie; Celada, Pau; Artigas, Francesc

    2016-09-01

    The antidepressant vortioxetine is a 5-HT3-R, 5-HT7-R and 5-HT1D-R antagonist, 5-HT1B-R partial agonist, 5-HT1A-R agonist, and serotonin (5-HT) transporter (SERT) inhibitor. Vortioxetine occupies all targets at high therapeutic doses and only SERT and 5-HT3-R at low doses. Vortioxetine increases extracellular monoamine concentrations in rat forebrain more than selective serotonin reuptake inhibitors (SSRI) and shows pro-cognitive activity in preclinical models. Given its high affinity for 5-HT3-R (Ki = 3.7 nM), selectively expressed in GABA interneurons, we hypothesized that vortioxetine may disinhibit glutamatergic and monoaminergic neurotransmission following 5-HT3-R blockade. Here we assessed vortioxetine effect on pyramidal neuron activity and extracellular 5-HT concentration using in vivo extracellular recordings of rat medial prefrontal cortex (mPFC) pyramidal neurons and microdialysis in mPFC and ventral hippocampus (vHPC). Vortioxetine, but not escitalopram, increased pyramidal neuron discharge in mPFC. This effect was prevented by SR57227A (5-HT3-R agonist) and was mimicked by ondansetron (5-HT3-R antagonist) and by escitalopram/ondansetron combinations. In microdialysis experiments, ondansetron augmented the 5-HT-enhancing effect of escitalopram in mPFC and vHPC. Local ondansetron in vHPC augmented escitalopram effect, indicating the participation of intrinsic mechanisms. Since 5-HT neurons express GABAB receptors, we examined their putative involvement in controlling 5-HT release after 5-HT3-R blockade. Co-perfusion of baclofen (but not muscimol) reversed the increased 5-HT levels produced by vortioxetine and escitalopram/ondansetron combinations in vHPC. The present results suggest that vortioxetine increases glutamatergic and serotonergic neurotransmission in rat forebrain by blocking 5-HT3 receptors in GABA interneurons.

  13. 5-HT2 receptors facilitate JC polyomavirus entry.

    PubMed

    Assetta, Benedetta; Maginnis, Melissa S; Gracia Ahufinger, Irene; Haley, Sheila A; Gee, Gretchen V; Nelson, Christian D S; O'Hara, Bethany A; Allen Ramdial, Stacy-ann A; Atwood, Walter J

    2013-12-01

    The human JC polyomavirus (JCPyV) causes the rapidly progressing demyelinating disease progressive multifocal leukoencephalopathy (PML). The disease occurs most often in individuals with AIDS but also occurs in individuals receiving immunomodulatory therapies for immune-related diseases such as multiple sclerosis. JCPyV infection of host cells requires the pentasaccharide lactoseries tetrasaccharide c (LSTc) and the serotonin receptor 5-hydroxytryptamine (5-HT) receptor 5-HT2AR. While LSTc is involved in the initial attachment of virus to cells via interactions with VP1, the mechanism by which 5-HT2AR contributes to infection is not clear. To further define the roles of serotonin receptors in infection, HEK293A cells, which are poorly permissive to JCPyV, were transfected with 14 different isoforms of serotonin receptor. Only 5-HT2 receptors were found to support infection by JCPyV. None of the other 11 isoforms of serotonin receptor supported JCPyV infection. Expression of 5-HT2 receptors did not increase binding of JCPyV to cells, but this was not unexpected, given that the cells uniformly expressed the major attachment receptor, LSTc. Infection of these cells remained sensitive to inhibition with soluble LSTc, confirming that LSTc recognition is required for JCPyV infection. Virus internalization into HEK293A cells was significantly and specifically enhanced when 5HT2 receptors were expressed. Taken together, these data confirm that the carbohydrate LSTc is the attachment receptor for JCPyV and that the type 2 serotonin receptors contribute to JCPyV infection by facilitating entry.

  14. Antidepressant-Like Activity of YL-0919: A Novel Combined Selective Serotonin Reuptake Inhibitor and 5-HT1A Receptor Agonist

    PubMed Central

    Zhang, Li-ming; Xue, Rui; Xu, Xiao-dan; Zhao, Nan; Qiu, Zhi-kun; Wang, Xian-wang; Zhang, You-zhi; Yang, Ri-fang; Li, Yun-feng

    2013-01-01

    It has been suggested that drugs combining activities of selective serotonin reuptake inhibitor and 5-HT1A receptor agonist may form a novel strategy for higher therapeutic efficacy of antidepressant. The present study aimed to examine the pharmacology of YL-0919, a novel synthetic compound with combined high affinity and selectivity for serotonin transporter and 5-HT1A receptors. We performed in vitro binding and function assays and in vivo behavioral tests to assess the pharmacological properties and antidepressant-like efficacy of YL-0919. YL-0919 displayed high affinity in vitro to both 5-HT1A receptor and 5-HT transporter prepared from rat cortical tissue. It exerted an inhibitory effect on forskolin-stimulated cAMP formation and potently inhibited 5-HT uptake in both rat cortical synaptosomes and recombinant cells. After acute p.o. administration, very low doses of YL-0919 reduced the immobility time in tail suspension test and forced swimming test in mice and rats, with no significant effect on locomotor activity in open field test. Furthermore, WAY-100635 (a selective 5-HT1A receptor antagonist, 0.3 mg/kg) significantly blocked the effect of YL-0919 in tail suspension test and forced swimming test. In addition, chronic YL-0919 treatment significantly reversed the depressive-like behaviors in chronically stressed rats. These findings suggest that YL-0919, a novel structure compound, exerts dual effect on the serotonergic system, as both 5-HT1A receptor agonist and 5-HT uptake blocker, showing remarkable antidepressant effects in animal models. Therefore, YL-0919 may be used as a new option for the treatment of major depressive disorder. PMID:24367588

  15. Antidepressant-like activity of YL-0919: a novel combined selective serotonin reuptake inhibitor and 5-HT1A receptor agonist.

    PubMed

    Chen, Hong-xia; Jin, Zeng-liang; Zhang, Li-ming; Xue, Rui; Xu, Xiao-dan; Zhao, Nan; Qiu, Zhi-kun; Wang, Xian-wang; Zhang, You-zhi; Yang, Ri-fang; Li, Yun-feng

    2013-01-01

    It has been suggested that drugs combining activities of selective serotonin reuptake inhibitor and 5-HT1A receptor agonist may form a novel strategy for higher therapeutic efficacy of antidepressant. The present study aimed to examine the pharmacology of YL-0919, a novel synthetic compound with combined high affinity and selectivity for serotonin transporter and 5-HT1A receptors. We performed in vitro binding and function assays and in vivo behavioral tests to assess the pharmacological properties and antidepressant-like efficacy of YL-0919. YL-0919 displayed high affinity in vitro to both 5-HT1A receptor and 5-HT transporter prepared from rat cortical tissue. It exerted an inhibitory effect on forskolin-stimulated cAMP formation and potently inhibited 5-HT uptake in both rat cortical synaptosomes and recombinant cells. After acute p.o. administration, very low doses of YL-0919 reduced the immobility time in tail suspension test and forced swimming test in mice and rats, with no significant effect on locomotor activity in open field test. Furthermore, WAY-100635 (a selective 5-HT1A receptor antagonist, 0.3 mg/kg) significantly blocked the effect of YL-0919 in tail suspension test and forced swimming test. In addition, chronic YL-0919 treatment significantly reversed the depressive-like behaviors in chronically stressed rats. These findings suggest that YL-0919, a novel structure compound, exerts dual effect on the serotonergic system, as both 5-HT1A receptor agonist and 5-HT uptake blocker, showing remarkable antidepressant effects in animal models. Therefore, YL-0919 may be used as a new option for the treatment of major depressive disorder.

  16. 5-HT6 receptors and Alzheimer's disease

    PubMed Central

    2013-01-01

    During the past 20 years, the 5-HT6 receptor has received increasing attention and become a promising target for improving cognition. Several studies with structurally different compounds have shown that not only antagonists but also 5-HT6 receptor agonists improve learning and memory in animal models. A large number of publications describing the development of ligands for this receptor have come to light, and it is now quite evident that 5-HT6 receptors have great pharmaceutical potential in terms of related patents. However, 5-HT6 receptor functionality is much more complex than initially defined. According to the existing data, different cellular pathways may be activated, depending on the drug being used. This article reviews preclinical and clinical evidence of the effects that 5-HT6 receptor compounds have on cognition. In addition, the biochemical and neurochemical mechanisms of action through which 5-HT6 receptor compounds can influence cognition will be described. Overall, several 5-HT6-targeted compounds can reasonably be regarded as powerful drug candidates for the treatment of Alzheimer's disease. PMID:23607787

  17. Stimulation of 5-HT1A, 5-HT1B, 5-HT2A/2C, 5-HT3 and 5-HT4 receptors or 5-HT uptake inhibition: short- and long-term memory.

    PubMed

    Meneses, Alfredo

    2007-11-22

    In order to determine whether short- (STM) and long-term memory (LTM) function in serial or parallel manner, serotonin (5-hydroxtryptamine, 5-HT) receptor agonists were tested in autoshaping task. Results show that control-vehicle animals were modestly but significantly mastering the autoshaping task as illustrated by memory scores between STM and LTM. Thus, post-training administration of 8-OHDPAT (agonist for 5-HT(1A/7) receptors) only at 0.250 and 0.500 mg/kg impaired both STM and LTM. CGS12066 (agonist for 5-HT(1B)) produced biphasic affects, at 5.0 mg/kg impaired STM but at 1.0 and 10.0 mg/kg, respectively, improved or impaired LTM. DOI (agonist for 5-HT(2A/2C) receptors) dose-dependently impaired STM and, at 10.0 mg/kg only impaired LTM. Both, STM and LTM were impaired by either mCPP (mainly agonist for 5-HT(2C) receptors) or mesulergine (mainly antagonist for 5-HT(2C) receptors) lower dose. The 5-HT(3) agonist mCPBG at 1.0 impaired STM and its higher dose impaired both STM and LTM. RS67333 (partial agonist for 5-HT(4) receptors), at 5.0 and 10.0 mg/kg facilitated both STM and LTM. The higher dose of fluoxetine (a 5-HT uptake inhibitor) improved both STM and LTM. Using as head-pokes during CS as an indirect measure of food-intake showed that of 30 memory changes, 21 of these were unrelated to the former. While some STM or LTM impairments can be attributed to decrements in food-intake, but not memory changes (either increase or decreases) produced by 8-OHDPAT, CGS12066, RS67333 or fluoxetine. Except for animals treated with DOI, mCPBG or fluoxetine, other groups treated with 5-HT agonists 6 h following autoshaping training showed similar LTM and unmodified CS-head-pokes scores.

  18. Vortioxetine restores reversal learning impaired by 5-HT depletion or chronic intermittent cold stress in rats.

    PubMed

    Wallace, Ashley; Pehrson, Alan L; Sánchez, Connie; Morilak, David A

    2014-10-01

    Current treatments for depression, including serotonin-specific reuptake inhibitors (SSRIs), are only partially effective, with a high incidence of residual symptoms, relapse, and treatment resistance. Loss of cognitive flexibility, a component of depression, is associated with dysregulation of the prefrontal cortex. Reversal learning, a form of cognitive flexibility, is impaired by chronic stress, a risk factor for depression, and the stress-induced impairment in reversal learning is sensitive to chronic SSRI treatment, and is mimicked by serotonin (5-HT) depletion. Vortioxetine, a novel, multimodal-acting antidepressant, is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, a 5-HT1B receptor partial agonist, a 5-HT1A receptor agonist, and inhibits the 5-HT transporter. Using adult male rats, we first investigated the direct effects of vortioxetine, acting at post-synaptic 5-HT receptors, on reversal learning that was compromised by 5-HT depletion using 4-chloro-DL-phenylalanine methyl ester hydrochloride (PCPA), effectively eliminating any contribution of 5-HT reuptake blockade. PCPA induced a reversal learning impairment that was alleviated by acute or sub-chronic vortioxetine administration, suggesting that post-synaptic 5-HT receptor activation contributes to the effects of vortioxetine. We then investigated the effects of chronic dietary administration of vortioxetine on reversal learning that had been compromised in intact animals exposed to chronic intermittent cold (CIC) stress, to assess vortioxetine's total pharmacological effect. CIC stress impaired reversal learning, and chronic vortioxetine administration prevented the reversal-learning deficit. Together, these results suggest that the direct effect of vortioxetine at 5-HT receptors may contribute to positive effects on cognitive flexibility deficits, and may enhance the effect of 5-HT reuptake blockade.

  19. 5-HT2A receptors are involved in cognitive but not antidepressant effects of fluoxetine.

    PubMed

    Castañé, Anna; Kargieman, Lucila; Celada, Pau; Bortolozzi, Analía; Artigas, Francesc

    2015-08-01

    The prefrontal cortex (PFC) plays a crucial role in cognitive and affective functions. It contains a rich serotonergic (serotonin, 5-HT) innervation and a high density of 5-HT receptors. Endogenous 5-HT exerts robust actions on the activity of pyramidal neurons in medial PFC (mPFC) via excitatory 5-HT2A and inhibitory 5-HT1A receptors, suggesting the involvement of 5-HT neurotransmission in cortical functions. However, the underlying mechanisms must be elucidated. Here we examine the role of 5-HT2A receptors in the processing of emotional and cognitive signals evoked by increasing the 5-HT tone after acute blockade of the 5-HT transporter. Fluoxetine (5-20mg/kg i.p.) dose-dependently reduced the immobility time in the tail-suspension test in wild-type (WT) and 5-HT2Aknockout (KO2A) mice, with non-significant differences between genotypes. Fluoxetine (10mg/kg i.p.) significantly impaired mice performance in the novel object recognition test 24h post-administration in WT, but not in KO2A mice. The comparable effect of fluoxetine on extracellular 5-HT in the mPFC of both genotypes suggests that presynaptic differences are not accountable. In contrast, single unit recordings of mPFC putative pyramidal neurons showed that fluoxetine (1.8-7.2mg/kg i.v.) significantly increased neuronal discharge in KO2A but not in WT mice. This effect is possibly mediated by an altered excitatory/inhibitory balance in the PFC in KO2A mice. Overall, the present results suggest that 5-HT2A receptors play a detrimental role in long-term memory deficits mediated by an excess 5-HT in PFC.

  20. Do imipramine and dihydroergosine possess two components - one stimulating 5-HT sub 1 and the other inhibiting 5-HT sub 2 receptors

    SciTech Connect

    Pericic, D.; Mueck-Seler, D. )

    1990-01-01

    The mechanisms by which imipramine and dihydroergosine stimulate the 5-HT syndrome in rats and inhibit the head-twitch response in rats and mice were studied. Imipramine- and dihydroergosine-included stimulation of the 5-HT syndrome was inhibited stereoselectively by propranolol, a high affinity ligand for 5-HT{sub 1} receptor sites, but not by ritanserin, a specific 5-HT{sub 2} receptor antagonist. (-) -Propranolol potentiated the inhibitory effect of imipramine, but not of dihydroergosine on the head-twitch response, while ritanserin was without effect. As expected, 8-OH-DPAT, a selective 5-HT{sub 1A} receptor agonist, stimulated, and 5-HT{sub 1B} agonists CGS 12066B and 1-(trifluoromethylphenyl) piperazine (TFMPP) failed to stimulate the 5-HT syndrome induced in rats by pargyline and 5-HTP administration. A higher dose of ritanserin inhibited the syndrome. While 8-OH-DPAT alone produced all behavioral components of the 5-HT syndrome, dihydroergosine or imipramine alone even at very high doses never produced tremor or a more intensive forepaw padding as seen when these drugs were given in combination with pargyline and 5-HTP. A single administration of (-)-propranolol also inhibited the head-twitch response. This effect lasted in mice longer that after ritanserin administration. In in vitro experiments dihydroergosine expressed approximately twenty-fold higher affinity for {sup 3}H-ketanserin binding sites than imipramine.

  1. Robust presynaptic serotonin 5-HT1B receptor inhibition of the striatonigral output and its sensitization by chronic fluoxetine treatment

    PubMed Central

    Ding, Shengyuan; Li, Li

    2015-01-01

    The striatonigral projection is a striatal output pathway critical to motor control, cognition, and emotion regulation. Its axon terminals in the substantia nigra pars reticulata (SNr) express a high level of serotonin (5-HT) type 1B receptors (5-HT1BRs), whereas the SNr also receives an intense 5-HT innervation that expresses 5-HT transporters, providing an anatomic substrate for 5-HT and selective 5-HT reuptake inhibitor (SSRI)-based antidepressant treatment to regulate the striatonigral output. In this article we show that 5-HT, by activating presynaptic 5-HT1BRs on the striatonigral axon terminals, potently inhibited the striatonigral GABA output, as reflected in the reduction of the striatonigral inhibitory postsynaptic currents in SNr GABA neurons. Functionally, 5-HT1BR agonism reduced the striatonigral GABA output-induced pause of the spontaneous high-frequency firing in SNr GABA neurons. Equally important, chronic SSRI treatment with fluoxetine enhanced this presynaptic 5-HT1BR-mediated pause reduction in SNr GABA neurons. Taken together, these results indicate that activation of the 5-HT1BRs on the striatonigral axon terminals can limit the motor-promoting GABA output. Furthermore, in contrast to the desensitization of 5-HT1 autoreceptors, chronic SSRI-based antidepressant treatment sensitizes this presynaptic 5-HT1BR-mediated effect in the SNr, a novel cellular mechanism that alters the striatonigral information transfer, potentially contributing to the behavioral effects of chronic SSRI treatment. PMID:25787955

  2. 5-HT induces cAMP production in crypt colonocytes at a 5-HT4 receptor.

    PubMed

    Albuquerque, F C; Smith, E H; Kellum, J M

    1998-07-01

    Previous studies demonstrate that both 5-hydroxytryptamine (5-HT) and cyclic AMP (cAMP) induce chloride efflux from crypt colonocytes in the rat distal colon; antagonist studies suggest that the 5-HT response is mediated primarily by the 5-HT4 receptor. Since this receptor is known to be positively coupled to adenylate cyclase, we postulated that 5-HT should induce generation of cAMP, which should be inhibited by 5-HT4 antagonists. Method. Mucosal cells from rat distal colon were taken by a sequential calcium chelation technique for enrichment of crypt cells. Cytokeratin stains demonstrated that >99% of cells were colonocytes. [3H]Thymidine uptake studies demonstrate a fivefold increased incorporation in this cell preparation compared to earlier fractions. 3-Isobutyl-l-methylxanthine (IBMX, 100 microM) was added to all cell suspensions in order to prevent cAMP metabolism. Cell suspensions were incubated for 2 min at 37 degreesC with different concentrations of 5-HT (n = 7). cAMP was measured by enzyme immunoassay. In another series of experiments, 5-HT (0.3 microM) stimulation of cAMP was similarly measured in the presence and absence of 5-HT receptor antagonists: 10 microM 5-HTP-DP (5-HT1P; n = 4), 0.1 microM ketanserin (5-HT2A; n = 4), 0.3 microM ondansetron (5-HT3; n = 4), 3 microM tropisetron (5-HT3 and 5-HT4; n = 4), and 10 nM GR-113808 (5-HT4; n = 5). Results. 5-HT produced a dose-dependent increase in cAMP. The increase was significant at concentrations >/=0.3 microM when compared to cells incubated with IBMX alone. In the second series of experiment, 5-HT-induced generation of cAMP at a dose of 0.3 microM was significantly inhibited in the presence of GR-113808 and tropisetron. Conclusion. 5-HT acts at a 5-HT4 receptor to induce production of cAMP in rat distal crypt colonocytes.

  3. Serotonergic 5-HT7 receptors and cognition.

    PubMed

    Gasbarri, Antonella; Pompili, Assunta

    2014-01-01

    The abundant distribution of serotonin (5-HT) in different areas of the central nervous system can explain the involvement of this neurotransmitter in the regulation of several functions, such as sleep, pain, feeding, and sexual and emotional behaviors. Moreover, the serotonergic system is also involved in other more complex roles, such as cognition, including learning and memory processes. Recent studies led to the discovery of various types and subtypes of receptors differentially associated to cognitive mechanisms. 5-HT7 is the most recently discovered receptor for 5-HT; therefore, it is also one of the least well characterized. Studies exist hypothesizing the role of 5-HT7 on the modulation of learning and memory processes and other cognitive functions. Moreover, much attention has been devoted to the possible role of 5-HT7 receptors in psychiatric disorders. Therefore, the aim of this review is to clarify the behavioral role of the recently discovered 5-HT7 type receptor and highlight its involvement in the cognitive functions, with particular attention to the modulation of learning and memory processes, thus providing a basis to obtain new therapeutic agents and strategies for the treatment of cognitive disorders.

  4. [5-HT1A/5-HT7 receptor interplay: Chronic activation of 5-HT7 receptors decreases the functional activity of 5-HT1A receptor and its сontent in the mouse brain].

    PubMed

    Kondaurova, E M; Bazovkina, D V; Naumenko, V S

    2017-01-01

    Serotonin receptors 5-HT1A and 5-HT7 are involved in the development of various psychopathologies. Some data indicate that there is an interplay between 5-HT1A 5-HT7 receptors that could be implicated in the regulation of their function. This work analyzed the effects of chronic 5-HT7 activation on the functional activity of 5-HT7 and 5-HT1A receptors, on the corresponding protein levels, and on the expression of genes encoding 5-HT7 and 5-HT1A receptors in the mouse brain. Chronic administration of the 5-HT7 selective agonist LP44 (20.5 nmol, i.c.v., 14 days) produced considerable desensitization of both 5-HT7 and 5-HT1A receptors. In LP44-treated mice, the hypothermic responses mediated by both 5-HT7 and 5-HT1A receptors were attenuated. Moreover, the levels of 5-HT1A receptor protein in the midbrain and the frontal cortex of LP44-treated mice were significantly decreased. However, the brain levels of 5-HT7 receptor protein did not differ between LP44-treated and control mice. Chronic LP44 treatment did not alter the expression of the 5-HT7 and 5-HT1A receptor genes in all investigated brain structure. These data suggest that 5-HT7 receptors participate in the posttranscriptional regulation of the 5-HT1A receptors functioning.

  5. Cloning, expression and pharmacology of a truncated splice variant of the human 5-HT7 receptor (h5-HT7(b))

    PubMed Central

    Jasper, J R; Kosaka, A; To, Z P; Chang, D J; Eglen, R M

    1997-01-01

    The rat 5-hydroxytryptamine (5-HT)7 receptor displays two splice variations, a long form, and a truncated splice isoform, arising from the introduction of a stop codon near the carboxy-terminus. The human 5-HT7 receptor gene contains at least two introns and encodes a 445 amino acid 5-HT receptor. A truncated splice variation in the human 5-HT7 receptor was isolated from a human placental cDNA library. In accordance with current NC-IUPHAR nomenclature guidelines, it is suggested that this receptor be denoted as the h5-HT7(b) receptor and the long form of the receptor as h5-HT7(a). The h5-HT7(b) receptor was stably expressed in HEK 293 cells and ligand affinities were determined by displacement of [3H]-5-carboxyamidotryptamine (5-CT; Kd=0.28±0.06 nM, Bmax=7.3±1.7 pmol mg−1 protein). The rank order of affinities (pKi) for a series of ligands was: 5-carboxamidotryptamine (5-CT, 9.65)>5-hydroxytryptamine (5-HT, 9.41)>methiothepin (8.87)>mesulergine (7.87)>8-hydroxy-2(di-n-propylamino)tetralin (8-OH-DPAT, 6.85)>ketanserin (6.44). The h5-HT7(b) receptor coupled positively to adenylyl cyclase in HEK 293 cells. This response was elicited by a number of agonists with the following order of potency (pEC50): 5-CT (8.7±0.11)>5-MeOT (5-methoxytryptamine; 8.1±0.20)>5-HT (7.5±0.13)>tryptamine (5.6±0.36)>8-OH-DPAT (5.3±0.28)>5-methoxytryptamine (5.0±0.06). This rank order was comparable to that observed in the radioligand binding studies. In a similar fashion to that described for the 5-HT7(a) receptor, PCR studies suggested that the 5-HT7(b) receptor mRNA is found in great abundance throughout the brain, in the small intestine and aorta. It is concluded that the h5-HT7 receptor, like the rat receptor, exists as splice variants exhibiting similar pharmacology, signal transduction and distribution. It is thus likely that there exists a complex physiological role for alternate splicing products of the 5-HT7 receptor gene. PMID:9298538

  6. Voltage-dependent transient currents of human and rat 5-HT transporters (SERT) are blocked by HEPES and ion channel ligands.

    PubMed

    Li, Ming; Farley, Robert A; Lester, Henry A

    2002-02-27

    The hyperpolarization-activated transient current of mammalian 5-hydroxytryptamine transporters (SERT) expressed in Xenopus oocytes was studied. Human (h) and rat (r) SERT transient currents are blocked by HEPES with changes in the waveform kinetics, and the blockade of hSERT has use-dependent properties. HEPES also changes the time course of the prepriming step, especially for hSERT. Transient currents at hSERT and rSERT are also blocked by spermine and spermidine in the mM range, and by fluoxetine, cocaine, QX-314, and QX-222 in the microM range. These pharmacological and kinetic properties of transient current blockade emphasize the similarities between the transient current and phenomena at ion channels.

  7. 5-HT1A and 5-HT7 receptors contribute to lurasidone-induced dopamine efflux.

    PubMed

    Huang, Mei; Horiguchi, Masakuni; Felix, Anna R; Meltzer, Herbert Y

    2012-05-09

    Lurasidone is a novel, atypical antipsychotic drug with serotonin [5-hydroxytryptamine (5-HT)]2A, 5-HT7, dopamine (DA) D2 antagonist, and 5-HT1A receptor partial agonist properties. The ability of lurasidone to reverse the effects of subchronic administration phencyclidine, to impair novel object recognition in rats, an animal model of cognitive impairment in schizophrenia, is dependent, in part, on its 5-HT1A agonist and 5-HT7 receptor antagonist properties. We tested whether 5-HT1A partial agonism or 5-HT7 antagonism, or both, contributed to the ability of lurasidone to enhance cortical and hippocampal DA efflux, which may be related to its ability to improve cognition. Here, we report that lurasidone, 0.25 and 0.5, but not 0.1 mg/kg, subcutaneously, significantly increased DA efflux in the prefrontal cortex and hippocampus in a dose-dependent manner. Lurasidone, 0.5 mg/kg, also produced a smaller increase in DA efflux in the nucleus accumbens. Pretreatment with the 5-HT1A receptor antagonist, WAY100635 (0.2 mg/kg, subcutaneously), partially blocked the lurasidone-induced cortical and hippocampal DA efflux. Further, subeffective doses of the 5-HT1A receptor agonist, tandospirone (0.2 mg/kg), or the 5-HT7 antagonist, SB269970 (0.3 mg/kg), potentiated the ability of a subeffective dose of lurasidone (0.1 mg/kg) to increase DA efflux in the prefrontal cortex. These findings suggest that the effects of lurasidone on the prefrontal cortex and hippocampus, DA efflux are dependent, at least partially, on its 5-HT1A agonist and 5-HT7 antagonist properties and may contribute to its efficacy to reverse the effects of subchronic phencyclidine treatment and improve schizophrenia.

  8. 5-HT Radioligands for Human Brain Imaging With PET and SPECT

    PubMed Central

    Paterson, Louise M.; Kornum, Birgitte R.; Nutt, David J.; Pike, Victor W.; Knudsen, Gitte M.

    2014-01-01

    The serotonergic system plays a key modulatory role in the brain and is the target for many drug treatments for brain disorders either through reuptake blockade or via interactions at the 14 subtypes of 5-HT receptors. This review provides the history and current status of radioligands used for positron emission tomography (PET) and single photon emission computerized tomography (SPECT) imaging of human brain serotonin (5-HT) receptors, the 5-HT transporter (SERT), and 5-HT synthesis rate. Currently available radioligands for in vivo brain imaging of the 5-HT system in humans include antagonists for the 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT4 receptors, and for SERT. Here we describe the evolution of these radioligands, along with the attempts made to develop radioligands for additional serotonergic targets. We describe the properties needed for a radioligand to become successful and the main caveats. The success of a PET or SPECT radioligand can ultimately be assessed by its frequency of use, its utility in humans, and the number of research sites using it relative to its invention date, and so these aspects are also covered. In conclusion, the development of PET and SPECT radioligands to image serotonergic targets is of high interest, and successful evaluation in humans is leading to invaluable insight into normal and abnormal brain function, emphasizing the need for continued development of both SPECT and PET radioligands for human brain imaging. PMID:21674551

  9. Platelet 5-HT(1A) receptor correlates with major depressive disorder in drug-free patients.

    PubMed

    Zhang, Zhang-Jin; Wang, Di; Man, Sui Cheung; Ng, Roger; McAlonan, Grainne M; Wong, Hei Kiu; Wong, Wendy; Lee, Jade; Tan, Qing-Rong

    2014-08-04

    The platelet serotonergic system has potential biomarker utility for major depressive disorder (MDD). In the present study, platelet expression of 5-HT1A receptors and serotonin transporter (SERT) proteins, and serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were quantified in 53 patients with MDD and 22 unaffected controls. All were drug-free, non-smokers and had no other psychiatric and cardiovascular comorbidity. The severity of depression symptoms was evaluated using the 17-item Hamilton Depression Rating Scale (HAMD-17) and the Self-rating Depression Scale (SDS). Patients with MDD had significantly higher expression of platelet 5-HT1A receptors but significantly lower contents of platelet 5-HT, platelet-poor plasma (PPP) 5-HT and PPP 5-HIAA compared to healthy controls, and this was correlated with the severity of depression. SERT expression did not differ between the two groups. Correlation analysis confirmed a strong, inverse relationship between the 5-HT1A receptor expression and the 5-HT and 5-HIAA levels. Thus overexpression of platelet 5-HT1A receptors and reduced 5-HT tone may function as a peripheral marker of depression.

  10. Memory formation and memory alterations: 5-HT6 and 5-HT7 receptors, novel alternative.

    PubMed

    Meneses, Alfredo

    2014-01-01

    Agonists and antagonists of the 5-hydroxytryptamine (serotonin) receptor6 (5-HT6) or receptor7 (5-HT7) might improve memory and/or reverse amnesia, although the mechanisms involved are poorly understood. Hence, the current work summarizes recent reviews and findings involving these receptors. Evidence indicates that diverse 5-HT6 receptor antagonists produce promnesic and/or antiamnesic effect in conditions, such as memory formation, age-related cognitive impairments and memory deficit in preclinical studies, as well as in diseases such as schizophrenia, Parkinson's, and Alzheimer's disease (AD). Memory, aging, and AD modify 5-HT6 receptors and signaling cascades; likewise, the modulation of 5-HT6 drugs on memory seems to be accompanied with neural changes. Moreover, 5-HT7 receptors are localized in brain areas mediating memory, including the cortex, hippocampus (e.g., Zola-Morgan and Squire, 1993) and raphe nuclei; however, the role of these receptors on memory has yet to be fully explored. Hence, findings and reviews are summarized in this work. Evidence suggests that both 5-HT7 receptor agonists and antagonists might have promnesic and anti-amnesic effects. These effects seem to be dependent on the basal level of performance, i.e., normal or impaired. Available evidence suggests that a potential utility of 5-HT6 and 5-HT7 receptor in mild-to-moderate AD patients and other memory dysfunctions as therapeutic targets.

  11. Interplay between serotonin 5-HT1A and 5-HT7 receptors in depressive disorders.

    PubMed

    Naumenko, Vladimir S; Popova, Nina K; Lacivita, Enza; Leopoldo, Marcello; Ponimaskin, Evgeni G

    2014-07-01

    Serotonin (5-hydroxytryptamine or 5-HT) is an important neurotransmitter regulating a wide range of physiological and pathological functions via activation of heterogeneously expressed 5-HT receptors. Besides the important role of 5-HT receptors in the pathogenesis of depressive disorders and in their clinical medications, underlying mechanisms are far from being completely understood. This review focuses on possible cross talk between two serotonin receptors, 5-HT1A and the 5-HT7 . Although these receptors are highly co-expressed in brain regions implicated in depression, and most agonists developed for the 5-HT1A or 5-HT7 receptors have cross-reactivity, their functional interaction has not been yet established. It has been recently shown that 5-HT1A and 5-HT7 receptors form homo- and heterodimers both in vitro and in vivo. From the functional point of view, heterodimerization has been shown to play an important role in regulation of receptor-mediated signaling and internalization, suggesting the implication of heterodimerization in the development and maintenance of depression. Interaction between these receptors is also of clinical interest, because both receptors represent an important pharmacological target for the treatment of depression and anxiety.

  12. Medial hypothalamic 5-hydroxytryptamine (5-HT)1A receptors regulate neuroendocrine responses to stress and exploratory locomotor activity: application of recombinant adenovirus containing 5-HT1A sequences.

    PubMed

    Li, Qian; Holmes, Andrew; Ma, Li; Van de Kar, Louis D; Garcia, Francisca; Murphy, Dennis L

    2004-12-01

    Our previous studies found that serotonin transporter (SERT) knock-out mice showed increased sensitivity to minor stress and increased anxiety-like behavior but reduced locomotor activity. These mice also showed decreased density of 5-hydroxytryptamine (5-HT1A) receptors in the hypothalamus, amygdala, and dorsal raphe. To evaluate the contribution of hypothalamic 5-HT1A receptors to these phenotypes of SERT knock-out mice, two studies were conducted. Recombinant adenoviruses containing 5-HT1A sense and antisense sequences (Ad-1AP-sense and Ad-1AP-antisense) were used to manipulate 5-HT1A receptors in the hypothalamus. The expression of the 5-HT1A genes is controlled by the 5-HT1A promoter, so that they are only expressed in 5-HT1A receptor-containing cells. (1) Injection of Ad-1AP-sense into the hypothalamus of SERT knock-out mice restored 5-HT1A receptors in the medial hypothalamus; this effect was accompanied by elimination of the exaggerated adrenocorticotropin responses to a saline injection (minor stress) and reduced locomotor activity but not by a change in increased exploratory anxiety-like behavior. (2) To further confirm the observation in SERT-/- mice, Ad-1AP-antisense was injected into the hypothalamus of normal mice. The density and the function of 5-HT1A receptors in the medial hypothalamus were significantly reduced in Ad-1AP-antisense-treated mice. Compared with the control group (injected with Ad-track), Ad-1A-antisense-treated mice showed a significant reduction in locomotor activity, but again no changes in exploratory anxiety-like behaviors, tested by elevated plus-maze and open-field tests. Thus, the present results demonstrate that medial hypothalamic 5-HT1A receptors regulate stress responses and locomotor activity but may not regulate exploratory anxiety-like behaviors.

  13. Serotonergic markers in platelets of patients with major depression: upregulation of 5-HT2 receptors.

    PubMed Central

    Hrdina, P D; Bakish, D; Chudzik, J; Ravindran, A; Lapierre, Y D

    1995-01-01

    The uptake of [3H]5-HT and the density (Bmax) as well as affinity (Kd) of 5-HT uptake sites labelled with [3H]paroxetine and of 5-HT2 receptors labelled by [3H]LSD were determined in platelets from 25 medication-free patients with major depression and 20 normal controls. The density (Bmax) of 5-HT2 receptors was found to be significantly increased (by 52%) in platelets from depressed patients, particularly females. No changes were found in the affinity (Kd) of 5-HT2 receptors and in 5-HT uptake or [3H]paroxetine binding parameters. Density of 5-HT2 receptors positively correlated with that of [3H]paroxetine sites in control but not in depressed subjects. No correlation was found between the HAMD scores and Bmax of [3H]LSD binding. The results suggest that upregulation of platelet 5-HT2 receptors is a useful biological marker in major depression, particularly in females. PMID:7865496

  14. Neuroticism and serotonin 5-HT1A receptors in healthy subjects.

    PubMed

    Hirvonen, Jussi; Tuominen, Lauri; Någren, Kjell; Hietala, Jarmo

    2015-10-30

    Neuroticism is a personality trait associated with vulnerability for mood and anxiety disorders. Serotonergic mechanisms likely contribute to neuroticism. Serotonin 5-HT1A receptors are altered in mood and anxiety disorders, but whether 5-HT1A receptors are associated with neuroticism in healthy subjects is unclear. We measured brain serotonin 5-HT1A receptor in 34 healthy subjects in vivo using positron emission tomography (PET) and [carbonyl-(11)C]WAY-100635. Binding potential (BPP) was determined using the golden standard of kinetic compartmental modeling using arterial blood samples and radiometabolite determination. Personality traits were assessed using the Karolinska Scales of Personality. We found a strong negative association between serotonin 5-HT1A receptor BPP and neuroticism. That is, individuals with high neuroticism tended to have lower 5-HT1A receptor binding than individuals with low neuroticism. This finding was confirmed with an independent voxel-based whole-brain analysis. Other personality traits did not correlate with 5-HT1A receptor BPP. Previous observations have reported lower serotonin 5-HT1A receptor density in major depression. This neurobiological finding may be a trait-like phenomenon and partly explained by higher neuroticism in patients with affective disorders. The link between personality traits and 5-HT1A receptors should be studied in patients with major depression.

  15. Memory time-course: mRNA 5-HT1A and 5-HT7 receptors.

    PubMed

    Perez-Garcia, Georgina; Meneses, Alfredo

    2009-08-24

    In an attempt to clarify conflicting results about serotonin (5-hydroxytryptamine, 5-HT) 5-HT(1A) and 5-HT(7) receptors in memory formation, their mRNA expression was determined by RT-PCR in key brain areas for explicit and implicit memory. The time-course (0-120 h) of autoshaped responses was progressive and mRNA 5-HT(1A) or 5-HT(7) receptors expression monotonically augmented or declined in prefrontal cortex, hippocampus and raphe nuclei, respectively. At 24-48 h acutely 8-OH-DPAT (0.062 mg/kg) administration enhanced memory and attenuated mRNA 5-HT(1A)<5-HT(7) receptors expression respect to saline group. WAY100635 (0.3 mg/kg) or SB-269970 (10.0 mg/kg) did not affect the former, partially blocked or reversed the latter, respectively. Furthermore, lower WAY100635 (0.001-0.1 mg/kg) or SB-269970 (1.0-5.0 mg/kg) doses plus 8-OHDPAT not affected memory; however both combinations suppressed or up-regulated mRNA expression 5-HT(1A) or 5-HT(7) receptors. In contrast, AS19 (5.0 mg/kg) facilitated memory consolidation, decreased or increased hippocampal 5-HT(7) and 5-HT(1A) receptors expression. Together these data revealed that, when both 5-HT(1A) and 5-HT(7) receptors were stimulated by 8-OHDPAT under memory consolidation, subtle changes emerged, not evident at behavioral level though detectable at genes expression. Notably, high levels of efficient memory were maintained even when serotonergic tone, via either 5-HT(1A) or 5-HT(7) receptor, was down- or up-regulated. Nevertheless, WAY100635 plus SB-269970 impaired memory consolidation and suppressed their expression. Considering that serotonergic changes are prominent in AD patients with an earlier onset of disease the present approach might be useful in the identification of functional changes associated to memory formation, memory deficits and reversing or even preventing these deficits.

  16. 5-Chloroindole: a potent allosteric modulator of the 5-HT3 receptor

    PubMed Central

    Newman, Amy S; Batis, Nikolaos; Grafton, Gillian; Caputo, Francesca; Brady, Catherine A; Lambert, Jeremy J; Peters, John A; Gordon, John; Brain, Keith L; Powell, Andrew D; Barnes, Nicholas M

    2013-01-01

    Background and Purpose The 5-HT3 receptor is a ligand-gated ion channel that is modulated allosterically by various compounds including colchicine, alcohols and volatile anaesthetics. However the positive allosteric modulators (PAMs) identified to date have low affinity, which hinders investigation because of non-selective effects at pharmacologically active concentrations. The present study identifies 5-chloroindole (Cl-indole) as a potent PAM of the 5-HT3 receptor. Experimental Approach 5-HT3 receptor function was assessed by the increase in intracellular calcium and single-cell electrophysiological recordings in HEK293 cells stably expressing the h5-HT3A receptor and also the mouse native 5-HT3 receptor that increases neuronal contraction of bladder smooth muscle. Key Results Cl-indole (1–100 μM) potentiated agonist (5-HT) and particularly partial agonist [(S)-zacopride, DDP733, RR210, quipazine, dopamine, 2-methyl-5-HT, SR57227A, meta chlorophenyl biguanide] induced h5-HT3A receptor-mediated responses. This effect of Cl-indole was also apparent at the mouse native 5-HT3 receptor. Radioligand-binding studies identified that Cl-indole induced a small (∼twofold) increase in the apparent affinity of 5-HT for the h5-HT3A receptor, whereas there was no effect upon the affinity of the antagonist, tropisetron. Cl-indole was able to reactivate desensitized 5-HT3 receptors. In contrast to its effect on the 5-HT3 receptor, Cl-indole did not alter human nicotinic α7 receptor responses. Conclusions and Implications The present study identifies Cl-indole as a relatively potent and selective PAM of the 5-HT3 receptor; such compounds will aid investigation of the molecular basis for allosteric modulation of the 5-HT3 receptor and may assist the discovery of novel therapeutic drugs targeting this receptor. Linked Articles Recent reviews on allosteric modulation can be found at: Kenakin, T (2013). New concepts in pharmacological efficacy at 7TM receptors: IUPHAR Review 2

  17. 5-HT1 agonists reduce 5-hydroxytryptamine release in rat hippocampus in vivo as determined by brain microdialysis.

    PubMed Central

    Sharp, T.; Bramwell, S. R.; Grahame-Smith, D. G.

    1989-01-01

    1. An intracerebral perfusion method, brain microdialysis, was used to assess changes of 5-hydroxytryptamine (5-HT) release in the ventral hippocampus of the chloral hydrate-anaesthetized rat in response to systemic administration of a variety of 5-HT1 receptor agonists. 2. A stable output of reliably detectable endogenous 5-HT was measured in dialysates collected from ventral hippocampus with the 5-HT reuptake inhibitor, citalopram, present in the perfusion medium. 3. Under these conditions the putative 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) caused a dose-dependent (5-250 micrograms kg-1, s.c.) reduction of 5-HT in hippocampal dialysates. 4. Similarly, the putative 5-HT1A agonists gepirone (5 mg kg-1, s.c.), ipsapirone (5 mg kg-1, s.c.) and buspirone (5 mg kg-1, s.c.) markedly reduced levels of 5-HT in hippocampal perfusates whereas their common metabolite 1-(2-pyrimidinyl) piperazine (5 mg kg-1, s.c.), which does not bind to central 5-HT1A recognition sites, had no effect. 5. 5-Methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole (RU 24969), a drug with reported high affinity for brain 5-HT1B binding sites, also produced a dose-dependent (0.25-5 mg kg-1, s.c.) decrease of hippocampal 5-HT output. 6. These data are direct biochemical evidence that systemically administered putative 5-HT1A and 5-HT1B agonists markedly inhibit 5-HT release in rat ventral hippocampus in vivo. PMID:2466516

  18. The 5-HT1-like receptor mediating the increase in canine external carotid blood flow: close resemblance to the 5-HT1D subtype.

    PubMed

    Villalón, C M; Terrón, J A

    1994-09-01

    1. It has recently been shown that the increase in external carotid blood flow induced by 5-hydroxy-tryptamine (5-HT) in the anaesthetized dog, being mimicked by 5-carboxamidotryptamine (5-CT), inhibited by methiothepin, vagosympathectomy and sympatho-inhibitory drugs, and resistant to blockade by ritanserin and MDL 72222, is mediated by stimulation of prejunctional 5-HT1-like receptors leading to an inhibitory action on carotid sympathetic nerves; these 5-HT1-like receptors are unrelated to either the 5-HT1A, 5-HT1B or 5-HT1C (now 5-HT2C) receptor subtypes. Inasmuch as 5-CT, 5-methoxytryptamine, sumatriptan and metergoline display high affinity, amongst other 5-HT binding sites, for the 5-HT1D subtype, in the present study we have used these drugs in an attempt to determine whether the above inhibitory prejunctional 5-HT1-like receptors correlate with the 5-HT1D subtype. 2. One-minute intracarotid (i.c.) infusions of 5-HT (0.3, 1, 3 and 10 micrograms), 5-CT (0.01, 0.03, 0.1 and 0.3 micrograms), 5-methoxytryptamine (1, 3, 10 and 30 micrograms) and sumatriptan (1, 3, 10, 30 and 100 micrograms) resulted in dose-dependent increases in external carotid blood flow (without changes in mean arterial blood pressure or heart rate) with the following rank order of agonist potency: 5-CT > 5-HT > 5-methoxytryptamine > or = sumatriptan. Interestingly, sumatriptan-induced vasodilatation was followed by a more pronounced vasoconstriction. 3. The external carotid vasodilator effects of 5-HT, 5-CT, 5-methoxytryptamine and sumatriptan were dose-dependently and specifically antagonized by metergoline (10, 30 and/or 100 micrograms kg-1, i.v.). In addition, 5-methoxytryptamine- and sumatriptan-induced vasodilator effects were, respectively, markedly inhibited or abolished after vagosympathectomy, as previously shown for 5-CT and 5-HT.4. Sumatriptan showed tachyphylaxis in its vasodilator component and antagonized 5-HT-induced external carotid vasodilatation in a specific manner

  19. A behavioural and biochemical study in mice and rats of putative selective agonists and antagonists for 5-HT1 and 5-HT2 receptors.

    PubMed Central

    Goodwin, G. M.; Green, A. R.

    1985-01-01

    Radioligand binding techniques have demonstrated the existence of 5-hydroxytryptamine (5-HT) binding subtypes: 5-HT2, 5-HT1A and 5-HT1B. These techniques have also indicated that certain drugs appear to show sub-type specificity: 8-hydroxy-2-(di-n-propylamino)tetralin(8-OH-DPAT), a 5-HT1A agonist; 5-methoxy-3(1,2,3,6-tetrahydropyridin-4-yl)1-H indole (RU 24969), a 5-HT1B agonist; and ritanserin, a 5-HT2 antagonist. (-)-Propranolol is a 5-HT1 antagonist of uncertain sub-type specificity. An examination has been made in mice and rats of the behavioural and biochemical effects of these drugs to determine whether the binding sites have physiological functions and further characterise the behavioural models. Administration of carbidopa (25 mg kg-1) plus 5-hydroxytryptophan (100 mg kg-1) produced head-twitch behaviour in mice which was antagonized by ritanserin (ED50 = 65 micrograms kg-1) but not (-)-propranolol (20 mg kg-1). 8-OH-DPAT (1-10 mg kg-1 s.c.) and RU 24949 (5 mg kg-1 i.p.) did not produce head-twitch behaviour. 8-OH-DPAT decreased 5-HTP- but not 5-methoxy-N-N-dimethyltryptamine (5 mg kg-1)-induced head-twitch by a (-)-propranolol-insensitive mechanism. Locomotor activity produced in mice by RU 24969 (3 mg kg-1) was antagonized by (-)-propranolol (20 mg kg-1) but not the (+)-isomer. (-)-Propranolol did not antagonize the behaviour induced in rats. In mice, both 8-OH-DPAT and RU 24969 markedly inhibited whole brain 5-HT synthesis and this effect was not antagonized by (-)-propranolol. In rats, 8-OH-DPAT (3 mg kg-1 s.c.) produced all the behavioural changes seen after quipazine (25 mg kg-1). (-)-Propranolol inhibited the behaviour changes produced by both agonists, while ritanserin antagonized the behaviour produced by quipazine but not 8-OH-DPAT. It is concluded, therefore, that the 5-HT1A receptor exists between the 5-HT2 receptor and the behavioural effectors. 8-OH-DPAT (at 20 degrees C ambient temperature) rapidly decreased rat body temperature, an effect

  20. Synthesis and Docking of Novel 3-Indolylpropyl Derivatives as New Polypharmacological Agents Displaying Affinity for 5-HT1A R/SERT.

    PubMed

    Pessoa-Mahana, Hernán; Silva-Matus, Paul; Pessoa-Mahana, C David; Chung, Hery; Iturriaga-Vásquez, Patricio; Quiroz, Gabriel; Möller-Acuña, Patricia; Zapata-Torres, Gerald; Saitz-Barría, Claudio; Araya-Maturana, Ramiro; Reyes-Parada, Miguel

    2017-01-01

    A series of novel 3-indolylpropyl derivatives was synthesized and evaluated for their binding affinities at the serotonin-1A receptor subtype (5-HT1A R) and the 5-HT transporter (SERT). Compounds 11b and 14b exhibited the highest affinities at the 5-HT1A R (Ki  = 43 and 56 nM), whereas compounds 11c and 14a were the most potent analogs at the SERT (Ki  = 34 and 17 nM). On the other hand, compounds 14b and 11d showed potent activity at both targets, displaying a profile that makes them promising leads for the search for novel potent ligands with a dual mechanism of action. Molecular docking studies in all the compounds unveiled relevant drug-target interactions, which allowed rationalizing the observed affinities.

  1. Effects of 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists on gastrointestinal motor activity in dogs

    PubMed Central

    Morita, Hiroki; Mochiki, Erito; Takahashi, Nobuyuki; Kawamura, Kiyoshi; Watanabe, Akira; Sutou, Toshinaga; Ogawa, Atsushi; Yanai, Mitsuhiro; Ogata, Kyoichi; Fujii, Takaaki; Ohno, Tetsuro; Tsutsumi, Souichi; Asao, Takayuki; Kuwano, Hiroyuki

    2013-01-01

    AIM: To study the effects of 5-hydroxytryptamine (5-HT) receptor antagonists on normal colonic motor activity in conscious dogs. METHODS: Colonic motor activity was recorded using a strain gauge force transducer in 5 dogs before and after 5-HT2B, 5-HT3 and 5-HT4 receptor antagonist administration. The force transducers were implanted on the serosal surfaces of the gastric antrum, terminal ileum, ileocecal sphincter and colon. Test materials or vehicle alone was administered as an intravenous bolus injection during a quiescent period of the whole colon in the interdigestive state. The effects of these receptor antagonists on normal gastrointestinal motor activity were analyzed. RESULTS: 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists had no contractile effect on the fasting canine terminal ileum. The 5-HT3 and 5-HT4 receptor antagonists inhibited phase III of the interdigestive motor complex of the antrum and significantly inhibited colonic motor activity. In the proximal colon, the inhibitory effect was dose dependent. Dose dependency, however, was not observed in the distal colon. The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity. CONCLUSION: The 5-HT3 and 5-HT4 receptor antagonists inhibited normal colonic motor activity. The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity. PMID:24151388

  2. Receptor and transporter binding and activity profiles of albiflorin extracted from Radix paeoniae Alba

    PubMed Central

    Jin, Zeng-liang; Gao, Nana; Xu, Weizhe; Xu, Pingxiang; Li, Shuaiqi; Zheng, Yuan-yuan; Xue, Ming

    2016-01-01

    Albiflorin, a traditional Chinese herb, is a main component of Radix paeoniae Alba, which has been used for the treatment of depressive disorders since ancient times. However, the mechanism of the antidepressant effect of albiflorin is poorly understood. Thus, we explored the binding profile of albiflorin at neurotransmitter receptors and transporters. We also characterised the in vivo effect of albiflorin on monoaminergic systems by using microanalysis to determine the extracellular levels of serotonin (5-HT) and norepinephrine (NE) in the hypothalamus of freely moving rats administered albiflorin. We found that albiflorin inhibited the uptake of 5-HT and NE and displayed robust binding affinities for the transporters of both neurotransmitters. By contrast, albiflorin (10 μM) showed no significant affinity to a wide array of central nervous system receptors. The results of our in vivo microdialysis studies showed that administration of albiflorin (3.5, 7.0, 14.0 mg/kg) significantly increased extracellular concentrations of 5-HT and NE in the hypothalamus of freely moving rats. Overall, the current study showed that albiflorin is a novel 5-HT and NE reuptake inhibitor with high selectivity. PMID:27646789

  3. MDMA-induced neurotoxicity: long-term effects on 5-HT biosynthesis and the influence of ambient temperature.

    PubMed

    O'Shea, Esther; Orio, Laura; Escobedo, Isabel; Sanchez, Veronica; Camarero, Jorge; Green, Alfred Richard; Colado, Maria Isabel

    2006-07-01

    1. 3,4-Methylenedioxymethamphetamine (MDMA or 'ecstasy') decreases the 5-HT concentration, [3H]-paroxetine binding and tryptophan hydroxylase activity in rat forebrain, which has been interpreted as indicating 5-HT neurodegeneration. This has been questioned, particularly the 5-HT loss, as MDMA can also inhibit tryptophan hydroxylase. We have now evaluated the validity of these parameters as a reflection of neurotoxicity. 2. Male DA rats were administered MDMA (12.5 mg kg(-1), i.p.) and killed up to 32 weeks later. 5-HT content and [3H]-paroxetine binding were measured in the cortex, hippocampus and striatum. Parallel groups of treated animals were administered NSD-1015 for determination of in vivo tryptophan hydroxylase activity and 5-HT turnover rate constant. 3. Tissue 5-HT content and [3H]-paroxetine binding were reduced in the cortex (26-53%) and hippocampus (25-74%) at all time points (1, 2, 4, 8 and 32 weeks). Hydroxylase activity was similarly reduced up to 8 weeks, but had recovered at 32 weeks. The striatal 5-HT concentration and [3H]-paroxetine binding recovered by week 4 and hydroxylase activity after week 1. In all regions, the reduction in 5-HT concentration did not result in an altered 5-HT synthesis rate constant. 4. Administering MDMA to animals when housed at 4 degrees C prevented the reduction in [3H]-paroxetine binding and hydroxylase activity observed in rats housed at 22 degrees C, but not the reduction in 5-HT concentration. 5. These data indicate that MDMA produces long-term damage to serotoninergic neurones, but this does not produce a compensatory increase in 5-HT synthesis in remaining terminals. It also highlights the fact that measurement of tissue 5-HT concentration may overestimate neurotoxic damage.

  4. Role of 5-HT1B, 5-HT2A and 5-HT2C receptors in learning.

    PubMed

    Meneses, A; Hong, E

    1997-08-01

    The effects of post-training (i.p.) injection of TFMPP, mCPP, DOI or 1-NP in the autoshaping learning task was explored. Furthermore, the post-training effects of these agonists after treatment with the antagonists (+/-)-pindolol, (+/-)-propranolol, NAN-190, ketanserin, ritanserin, mesulergine, MDL-72222 or p-chloroamphetamine (5-HT depleter) were studied. Rats were individually trained with a lever-press response (conditioned response; CR) on the autoshaping task and tested 24 h later. The results showed that the injection of TFMPP (1-10 mg/kg), mCPP (1-10 mg/kg), 1-NP (0.1-1.0 mg/kg) or mesulergine (0.4 mg/kg) decreased the rate of CR, while DOI (0.01-0.1 mg/kg) and ritanserin (0.5 mg/kg) and ketanserin (0.001-0.1 mg/kg) increased it. However, the effect induced by TFMPP was reversed by (+/-)-pindolol, ketanserin, ritanserin and PCA; the mCPP-induced effect was antagonized by (+/-)-propranolol, ketanserin, ritanserin and MDL-72222; and the effect produced by 1-NP was reversed by ketanserin, ritanserin and PCA. In addition, the increment in CR provoked by DOI was enhanced by ketanserin, and reversed by ritanserin, mesulergine and PCA. These findings suggest that TFMPP, 1-NP and DOI exerted their effects via stimulation of presynaptic 5-HT receptors. The effects of mCPP most probably reflect activation of postsynaptic receptors. The present data suggest that both 5-HT1B and 5-HT2A-2C receptors play a significant role in the consolidation of learning.

  5. Individual Differences in Impulsive Action Reflect Variation in the Cortical Serotonin 5-HT2A Receptor System

    PubMed Central

    Fink, Latham HL; Anastasio, Noelle C; Fox, Robert G; Rice, Kenner C; Moeller, F Gerard; Cunningham, Kathryn A

    2015-01-01

    Impulsivity is an important feature of multiple neuropsychiatric disorders, and individual variation in the degree of inherent impulsivity could play a role in the generation or exacerbation of problematic behaviors. Serotonin (5-HT) actions at the 5-HT2AR receptor (5-HT2AR) promote and 5-HT2AR antagonists suppress impulsive action (the inability to withhold premature responses; motor impulsivity) upon systemic administration or microinfusion directly into the medial prefrontal cortex (mPFC), a node in the corticostriatal circuit that is thought to play a role in the regulation of impulsive action. We hypothesized that the functional capacity of the 5-HT2AR, which is governed by its expression, localization, and protein/protein interactions (eg, postsynaptic density 95 (PSD95)), may drive the predisposition to inherent impulsive action. Stable high-impulsive (HI) and low-impulsive (LI) phenotypes were identified from an outbred rodent population with the 1-choice serial reaction time (1-CSRT) task. HI rats exhibited a greater head-twitch response following administration of the preferential 5-HT2AR agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) and were more sensitive to the effects of the selective 5-HT2AR antagonist M100907 to suppress impulsive action relative to LI rats. A positive correlation was observed between levels of premature responses and 5-HT2AR binding density in frontal cortex ([3H]-ketanserin radioligand binding). Elevated mPFC 5-HT2AR protein expression concomitant with augmented association of the 5-HT2AR with PSD95 differentiated HI from LI rats. The observed differential sensitivity of HI and LI rats to 5-HT2AR ligands and associated distinct 5-HT2AR protein profiles provide evidence that spontaneously occurring individual differences in impulsive action reflect variation in the cortical 5-HT2AR system. PMID:25666313

  6. Predictive In Silico Studies of Human 5-hydroxytryptamine Receptor Subtype 2B (5-HT2B) and Valvular Heart Disease

    PubMed Central

    Reid, Terry-Elinor; Kumar, Krishna

    2014-01-01

    Serotonin (5-HT) receptors are neuromodulator neurotransmitter receptors which when activated generate a signal transduction pathway within cells resulting in cell-cell communication. 5-hydroxytryptamine (serotonin) receptor 2B (5-HT2B) is a subtype of the seven members of 5-hydroxytrytamine (5-HT) family of receptors which is the largest member of the super family of 7-transmembrane G-protein coupled receptors (GPCRs). Not only do 5-HT receptors play physiological roles in the cardiovascular system, gastrointestinal and endocrine function and the central nervous, but they also play a role in behavioral functions. In particular 5-HT2B receptor is wide spread with regards to its distribution throughout bodily tissues and is expressed at high levels in the lungs, peripheral tissues, liver, kidney and prostate just to name a few. Hence 5-HT2B participates in multiple biological functions including CNS regulation, regulation of gastrointestinal motality, cardiovascular regulation and 5-HT transport system regulation. While 5-HT2B is a viable drug target and has therapeutic indications for treating obesity, psychotherapy, Parkinson’s disease etc. there is a growing concern regarding adverse drug reactions, specifically valvulopathy associated with 5-HT2B agonists. Due to the sequence homology experienced by 5-HT2 subtypes there is also a concern regarding the off target effects of 5-HT2A and 5-HT2C agonists. The concept of subtype selectivity is of paramount importance and can be tackled with the aid of in silico studies, specifically cheminformatics, to develop models to predict valvulopathy associated toxicity of drug candidates prior to clinical trials. This review has highlighted three in silico approaches thus far that have been successful in either predicting 5-HT2B toxicity of molecules or identifying important interactions between 5-HT2B and drug molecules that bring about valvulopathy related toxicities. PMID:23675941

  7. Aminoalkyl Derivatives of 8-Alkoxypurine-2,6-diones: Multifunctional 5-HT1A /5-HT7 Receptor Ligands and PDE Inhibitors with Antidepressant Activity.

    PubMed

    Chłoń-Rzepa, Grażyna; Zagórska, Agnieszka; Żmudzki, Paweł; Bucki, Adam; Kołaczkowski, Marcin; Partyka, Anna; Wesołowska, Anna; Kazek, Grzegorz; Głuch-Lutwin, Monika; Siwek, Agata; Starowicz, Gabriela; Pawłowski, Maciej

    2016-12-01

    In the search for potential psychotropic agents, a new series of 3,7-dimethyl- and 1,3-dimethyl-8-alkoxypurine-2,6-dione derivatives of arylpiperazines, perhydroisoquinolines, or tetrahydroisoquinolines with flexible alkylene spacers (5-16 and 21-32) were synthesized and evaluated for 5-HT1A /5-HT7 receptor affinities as well as PDE4B1 and PDE10A inhibitory properties. The 1-(4-(4-(2-hydroxyphenyl)piperazin-1-yl)butyl)-3,7-dimethyl-8-propoxypurine-2,6-dione (16) and 7-(2-hydroxyphenyl)piperazinylalkyl-1,3-dimethyl-8-ethoxypurine-2,6-diones (31 and 32) as potent dual 5-HT1A /5-HT7 receptor ligands with antagonistic activity produced an antidepressant-like effect in the forced swim test in mice. This effect was similar to that produced by citalopram. All the tested compounds were stronger phosphodiesterase isoenzyme inhibitors than theophylline and theobromine. The most potent compounds, 15 and 16, were characterized by 51 and 52% inhibition, respectively, of PDE4B1 activity at a concentration of 10(-5)  M. Concerning the above findings, it may be assumed that the inhibition of PDE4B1 may impact on the signal strength and specificity resulting from antagonism toward the 5-HT1 and 5-HT7 receptors, especially in the case of compounds 15 and 16. This dual receptor and enzyme binding mode was analyzed and explained via molecular modeling studies.

  8. Pet imaging of human pituitary 5-HT2 receptors with F-18 setoperone

    SciTech Connect

    Fischman, A.J.; Bonab, A.A.; Babich, J.W.

    1995-05-01

    Serotonin (5-HT) receptors play an important role in the regulation of pituitary function. In particular, 5HT agonists stimulate ACTH, {beta}-endorphin, prolactin and growth hormone secretion but inhibit TSH release. 5-HT binding sites have been identified by autoradiographic studies of rat and human pituitary. In the present investigation, we used PET with F-18 setoperone to image 5-HT2 receptors in normal humans. Setoperone, a piperidine derivative with potent 5-HT2 receptor blocking properties was labelled with F-18 by nucleophilic substitution on the nitro derivative. After HPLC purification, specific activity was between 10,000 and 15,000 mCi/{mu} mole and radiochemical purity was >98%. Six healthy male volunteers were injected with 5-7 mCi of F-18. Setoperone and serial PET images and arterial blood samples were collected over 2 hrs. Specific binding to 5-HT2 receptors in the frontal cortex (FC), striatum (ST) and pituitary (P) was quantitated using the cerebellum (C) as reference. The tracer showed clear retention in FC, ST and P (known to contain a high density of 5-HT2 receptors) relative to C (known to be devoid of 5-HT2 receptors). In all subjects, FC/C, ST/C and P/C ratios increased during the first hr. and remained stable thereafter. For FC and ST, the ratios reached similar values; 3.92{plus_minus}0.73 and 3.53{plus_minus}0.32. For pituitary, a significantly higher ratio, was measured at all times; 6.53{plus_minus}1.82 (p<0.01). These results indicate that F-18 setoperone is an effective PET radiopharmaceutical for imaging 5-HT2 receptors in the human pituitary. Future applications of this agent could provide important new insights into neuroendocrine function.

  9. Constitutively Active 5-HT Receptors: An Explanation of How 5-HT Antagonists Inhibit Gut Motility in Species Where 5-HT is Not an Enteric Neurotransmitter?

    PubMed Central

    Spencer, Nick J.

    2015-01-01

    Antagonists of 5-Hydroxytryptamine (5-HT) receptors are well known to inhibit gastrointestinal (GI)-motility and transit in a variety of mammals, including humans. Originally, these observations had been interpreted by many investigators (including us) as evidence that endogenous 5-HT plays a major role in GI motility. This seemed a logical assumption. However, the story changed dramatically after recent studies revealed that 5-HT antagonists still blocked major GI motility patterns (peristalsis and colonic migrating motor complexes) in segments of intestine depleted of all 5-HT. Then, these results were further supported by Dr. Gershons' laboratory, which showed that genetic deletion of all genes that synthesizes 5-HT had minor, or no inhibitory effects on GI transit in vivo. If 5-HT was essential for GI motility patterns and transit, then one would expect major disruptions in motility and transit when 5-HT synthesis was genetically ablated. This does not occur. The inhibitory effects of 5-HT antagonists on GI motility clearly occur independently of any 5-HT in the gut. Evidence now suggests that 5-HT antagonists act on 5-HT receptors in the gut which are constitutively active, and don't require 5-HT for their activation. This would explain a long-standing mystery of how 5-HT antagonists inhibit gut motility in species like mice, rats, and humans where 5-HT is not an enteric neurotransmitter. Studies are now increasingly demonstrating that the presence of a neurochemical in enteric neurons does not mean they function as neurotransmitters. Caution should be exercised when interpreting any inhibitory effects of 5-HT antagonists on GI motility. PMID:26732863

  10. Dopamine neurotransmission is involved in the attenuating effects of 5-HT3 receptor antagonist MDL 72222 on acute methamphetamine-induced locomotor hyperactivity in mice.

    PubMed

    Yoo, Ji-Hoon; Nam, Yun-Sun; Lee, Seok-Yong; Jang, Choon-Gon

    2008-01-01

    We have previously shown that 5-HT3 receptors are involved in the development and expression of methamphetamine (MAP)-induced locomotor sensitization in mice. In the present study, we further examined whether the dopaminergic system is involved in the attenuating effects of MDL 72222, a 5-HT3 receptor antagonist, on acute MAP-induced locomotor hyperactivity. For this, we examined alterations of dopamine (DA) in the form of D1 receptor, D2 receptor, and dopamine transporter (DAT) binding labeled with [3H]SCH23390 for D1, [3H]raclopride for D2, and [3H]mazindol for DAT binding in the mouse brains with acute MAP exposure or pretreatment of MDL 72222 with MAP. No significant differences were detected in the D1 receptor, D2 receptor, or DAT binding between any of the groups studied. Interestingly, we found increased DA levels in the striatum following acute MAP exposure; these increased levels were reversed by pretreatment with MDL 72222, but did not affect 5-HT levels in the dorsal raphe. Overall, our results suggest that dopamine neurotransmission plays an important role in the attenuating effects of 5-HT3 receptor antagonist MDL 72222 on acute MAP-induced locomotor hyperactivity in mice.

  11. Synthesis and evaluation of methylated arylazepine compounds for PET imaging of 5-HT(2c) receptors.

    PubMed

    Granda, Michael L; Carlin, Stephen M; Moseley, Christian K; Neelamegam, Ramesh; Mandeville, Joseph B; Hooker, Jacob M

    2013-02-20

    The serotonin 5-HT(2c) receptor is implicated in a number of diseases including obesity, depression, anxiety, and schizophrenia. In order to ascribe the role of 5-HT(2c) in these diseases, a method for measuring 5-HT(2c )density and function in vivo, such as with positron emission tomography (PET), must be developed. Many high-affinity and relatively selective ligands exist for 5-HT(2c) but cannot be accessed with current radiosynthetic methods for use as PET radiotracers. We propose that N-methylation of an arylazepine moiety, a frequent structural feature in 5-HT(2c) ligands, may be a suitable method for producing new radiotracers for 5-HT(2c). The impact of N-methylation has not been previously reported. For the agonists that we selected herein, N-methylation was found to increase affinity up to 8-fold without impairing selectivity. Compound 5, an N-methylated azetidine-derived arylazepine, was found to be brain penetrant and reached a brain/blood ratio of 2.05:1. However, our initial test compound was rapidly metabolized within 20 min of administration and exhibited high nonspecific binding. N-Methylation, with 16 ± 3% isolated radiochemical yield (decay corrected), is robust and may facilitate screening other 5-HT(2c) ligands as radiotracers for PET.

  12. Synthesis and Evaluation of Methylated Arylazepine Compounds for PET Imaging of 5-HT2c Receptors

    PubMed Central

    2012-01-01

    The serotonin 5-HT2c receptor is implicated in a number of diseases including obesity, depression, anxiety, and schizophrenia. In order to ascribe the role of 5-HT2c in these diseases, a method for measuring 5-HT2c density and function in vivo, such as with positron emission tomography (PET), must be developed. Many high-affinity and relatively selective ligands exist for 5-HT2c but cannot be accessed with current radiosynthetic methods for use as PET radiotracers. We propose that N-methylation of an arylazepine moiety, a frequent structural feature in 5-HT2c ligands, may be a suitable method for producing new radiotracers for 5-HT2c. The impact of N-methylation has not been previously reported. For the agonists that we selected herein, N-methylation was found to increase affinity up to 8-fold without impairing selectivity. Compound 5, an N-methylated azetidine-derived arylazepine, was found to be brain penetrant and reached a brain/blood ratio of 2.05:1. However, our initial test compound was rapidly metabolized within 20 min of administration and exhibited high nonspecific binding. N-Methylation, with 16 ± 3% isolated radiochemical yield (decay corrected), is robust and may facilitate screening other 5-HT2c ligands as radiotracers for PET. PMID:23421677

  13. Sex differences in the serotonin 1A receptor and serotonin transporter binding in the human brain measured by PET.

    PubMed

    Jovanovic, Hristina; Lundberg, Johan; Karlsson, Per; Cerin, Asta; Saijo, Tomoyuki; Varrone, Andrea; Halldin, Christer; Nordström, Anna-Lena

    2008-02-01

    Women and men differ in serotonin associated psychiatric conditions, such as depression, anxiety and suicide. Despite this, very few studies focus on sex differences in the serotonin system. Of the biomarkers in the serotonin system, serotonin(1A) (5-HT(1A)) receptor is implicated in depression, and anxiety and serotonin transporter (5-HTT) is a target for selective serotonin reuptake inhibitors, psychotropic drugs used in the treatment of these disorders. The objective of the present study was to study sex related differences in the 5-HT(1A) receptor and 5-HTT binding potentials (BP(ND)s) in healthy humans, in vivo. Positron emission tomography and selective radioligands [(11)C]WAY100635 and [(11)C]MADAM were used to evaluate binding potentials for 5-HT(1A) receptors (14 women and 14 men) and 5-HTT (8 women and 10 men). The binding potentials were estimated both on the level of anatomical regions and voxel wise, derived by the simplified reference tissue model and wavelet/Logan plot parametric image techniques respectively. Compared to men, women had significantly higher 5-HT(1A) receptor and lower 5-HTT binding potentials in a wide array of cortical and subcortical brain regions. In women, there was a positive correlation between 5-HT(1A) receptor and 5-HTT binding potentials for the region of hippocampus. Sex differences in 5-HT(1A) receptor and 5-HTT BP(ND) may reflect biological distinctions in the serotonin system contributing to sex differences in the prevalence of psychiatric disorders such as depression and anxiety. The result of the present study may help in understanding sex differences in drug treatment responses to drugs affecting the serotonin system.

  14. The 5-HT1-like receptors mediating inhibition of sympathetic vasopressor outflow in the pithed rat: operational correlation with the 5-HT1A, 5-HT1B and 5-HT1D subtypes

    PubMed Central

    Villalón, Carlos M; Centurión, David; Rabelo, Gonzalo; de Vries, Peter; Saxena, Pramod R; Sánchez-López, Araceli

    1998-01-01

    It has been suggested that the inhibition of sympathetically-induced vasopressor responses produced by 5-hydroxytryptamine (5-HT) in pithed rats is mediated by 5-HT1-like receptors. The present study has re-analysed this suggestion with regard to the classification schemes recently proposed by the NC-IUPHAR subcommittee on 5-HT receptors.Intravenous (i.v.) continuous infusions of 5-HT and the 5-HT1 receptor agonists, 8-OH-DPAT (5-HT1A), indorenate (5-HT1A), CP 93,129 (5-HT1B) and sumatriptan (5-HT1B/1D), resulted in a dose-dependent inhibition of sympathetically-induced vasopressor responses.The sympatho-inhibitory responses induced by 5-HT, 8-OH-DPAT, indorenate, CP 93,129 or sumatriptan were analysed before and after i.v. treatment with blocking doses of the putative 5-HT receptor antagonists, WAY 100635 (5-HT1A), cyanopindolol (5-HT1A/1B) or GR 127935 (5-HT1B/1D). Thus, after WAY 100635, the responses to 5-HT and indorenate, but not to 8-OH-DPAT, CP 93,129 and sumatriptan, were blocked. After cyanopindolol, the responses to 5-HT, indorenate and CP 93,129 were abolished, whilst those to 8-OH-DPAT and sumatriptan (except at the lowest frequency of stimulation) remained unaltered. In contrast, after GR 127935, the responses to 5-HT, CP 93,129 and sumatriptan, but not to 8-OH-DPAT and indorenate, were abolished.In additional experiments, the inhibition induced by 5-HT was not modified after 5-HT7 receptor blocking doses of mesulergine.The above results suggest that the 5-HT1-like receptors, which inhibit the sympathetic vasopressor outflow in pithed rats, display the pharmacological profile of the 5-HT1A, 5-HT1B and 5-HT1D, but not that of 5-HT7, receptors. PMID:9692787

  15. Regulatory role of a neurotransmitter (5-HT) on glial Na+/K(+)-ATPase in the rat brain.

    PubMed

    Mercado, R; Hernández, J

    1992-07-01

    In the present work we studied the effect of serotonin (5-HT) on the kinetics of Na+/K(+)-ATPase in subcellular preparations of the cerebral cortex from male Wistar rats using various concentrations of ATP and K+ with and without added 5-HT. Also we studied the effect of 5-HT on the enzyme in glial or neuronal preparations. The results indicated that there was a significant increase (P < 0.05) of the Vmax in the presence of 5-HT in the whole tissue preparation (homogenate) but not in the subcellular fractions, suggesting that the interaction could be preferentially with the glial pump. Further results supported that this was the case since activation by 5-HT was mainly in the glial preparations. Kinetic data and the binding of [3H]ouabain supported that the enzyme is activated by 5-HT through the exposure of more enzymatic active sites.

  16. Selective 5HT2A and 5HT6 Receptor Antagonists Promote Sleep in Rats

    PubMed Central

    Morairty, Stephen R.; Hedley, Linda; Flores, Judith; Martin, Renee; Kilduff, Thomas S.

    2008-01-01

    Study Objectives: Serotonin (5-HT) has long been implicated in the control of sleep and wakefulness. This study evaluated the hypnotic efficacy of the 5-HT6 antagonist RO4368554 (RO) and the 5-HT2A receptor antagonist MDL100907 (MDL) relative to zolpidem. Design: A randomized, repeated-measures design was utilized in which Wistar rats received intraperitoneal injections of RO (1.0, 3.0, and 10 mg/kg), MDL (0.1, 1.0 and 3.0 mg/kg), zolpidem (10 mg/kg), or vehicle in the middle of the dark (active) period. Electroencephalogram, electromyogram, body temperature (Tb) and locomotor activity were analyzed for 6 hours after injection. Measurements and Results: RO, MDL, and zolpidem all produced significant increases in sleep and decreases in waking, compared with vehicle control. All 3 doses of MDL produced more consolidated sleep, increased non-rapid eye movement sleep (NREM) sleep, and increased electroencephalographic delta power during NREM sleep. The highest dose of RO (10.0 mg/kg) produced significant increases in sleep and decreases in waking during hour 2 following dosing. These increases in sleep duration were associated with greater delta power during NREM sleep. ZO Zolpidem induced sleep with the shortest latency and significantly increased NREM sleep and delta power but also suppressed rapid eye movement sleep sleep; in contrast, neither RO nor MDL affected rapid eye movement sleep. Whereas RO did not affect Tb, both zolpidem and MDL reduced Tb relative to vehicle-injected controls. Conclusions: These results support a role for 5-HT2A receptor modulation in NREM sleep and suggest a previously unrecognized role for 5-HT6 receptors in sleep-wake regulation. Citation: Morairty SR; Hedley L; Flores J; Martin R; Kilduff TS. Selective 5HT2A and 5HT6 receptor antagonists promote sleep in rats. SLEEP 2008;31(1):34-44. PMID:18220076

  17. 5-HT(2B) receptors are required for serotonin-selective antidepressant actions.

    PubMed

    Diaz, S L; Doly, S; Narboux-Nême, N; Fernández, S; Mazot, P; Banas, S M; Boutourlinsky, K; Moutkine, I; Belmer, A; Roumier, A; Maroteaux, L

    2012-02-01

    The therapeutic effects induced by serotonin-selective reuptake inhibitor (SSRI) antidepressants are initially triggered by blocking the serotonin transporter and rely on long-term adaptations of pre- and post-synaptic receptors. We show here that long-term behavioral and neurogenic SSRI effects are abolished after either genetic or pharmacological inactivation of 5-HT(2B) receptors. Conversely, direct agonist stimulation of 5-HT(2B) receptors induces an SSRI-like response in behavioral and neurogenic assays. Moreover, the observation that (i) this receptor is expressed by raphe serotonergic neurons, (ii) the SSRI-induced increase in hippocampal extracellular serotonin concentration is strongly reduced in the absence of functional 5-HT(2B) receptors and (iii) a selective 5-HT(2B) agonist mimics SSRI responses, supports a positive regulation of serotonergic neurons by 5-HT(2B) receptors. The 5-HT(2B) receptor appears, therefore, to positively modulate serotonergic activity and to be required for the therapeutic actions of SSRIs. Consequently, the 5-HT(2B) receptor should be considered as a new tractable target in the combat against depression.

  18. Side effect profile of 5-HT treatments for Parkinson's disease and L-DOPA-induced dyskinesia in rats

    PubMed Central

    Lindenbach, D; Palumbo, N; Ostock, C Y; Vilceus, N; Conti, M M; Bishop, C

    2015-01-01

    BACKGROUND AND PURPOSE Treatment of Parkinson's disease (PD) with L-DOPA eventually causes abnormal involuntary movements known as dyskinesias in most patients. Dyskinesia can be reduced using compounds that act as direct or indirect agonists of the 5-HT1A receptor, but these drugs have been reported to worsen PD features and are known to produce ‘5-HT syndrome’, symptoms of which include tremor, myoclonus, rigidity and hyper-reflexia. EXPERIMENTAL APPROACH Sprague-Dawley rats were given unilateral nigrostriatal dopamine lesions with 6-hydroxydopamine. Each of the following three purportedly anti-dyskinetic 5-HT compounds were administered 15 min before L-DOPA: the full 5-HT1A agonist ±-8-hydroxy-2-dipropylaminotetralin (±8-OH-DPAT), the partial 5-HT1A agonist buspirone or the 5-HT transporter inhibitor citalopram. After these injections, animals were monitored for dyskinesia, 5-HT syndrome, motor activity and PD akinesia. KEY RESULTS Each 5-HT drug dose-dependently reduced dyskinesia by relatively equal amounts (±8-OH-DPAT ≥ citalopram ≥ buspirone), but 5-HT syndrome was higher with ±8-OH-DPAT, lower with buspirone and not present with citalopram. Importantly, with or without L-DOPA, all three compounds provided an additional improvement of PD akinesia. All drugs tempered the locomotor response to L-DOPA suggesting dyskinesia reduction, but vertical rearing was reduced with 5-HT drugs, potentially reflecting features of 5-HT syndrome. CONCLUSIONS AND IMPLICATIONS The results suggest that compounds that indirectly facilitate 5-HT1A receptor activation, such as citalopram, may be more effective therapeutics than direct 5-HT1A receptor agonists because they exhibit similar anti-dyskinesia efficacy, while possessing a reduced side effect profile. PMID:25175895

  19. A short history of the 5-HT2C receptor: from the choroid plexus to depression, obesity and addiction treatment.

    PubMed

    Palacios, Jose M; Pazos, Angel; Hoyer, Daniel

    2017-03-07

    This paper is a personal account on the discovery and characterization of the 5-HT2C receptor (first known as the 5-HT1C receptor) over 30 years ago and how it translated into a number of unsuspected features for a G protein-coupled receptor (GPCR) and a diversity of clinical applications. The 5-HT2C receptor is one of the most intriguing members of the GPCR superfamily. Initially referred to as 5-HT1CR, the 5-HT2CR was discovered while studying the pharmacological features and the distribution of [(3)H]mesulergine-labelled sites, primarily in the brain using radioligand binding and slice autoradiography. Mesulergine (SDZ CU-085), was, at the time, best defined as a ligand with serotonergic and dopaminergic properties. Autoradiographic studies showed remarkably strong [(3)H]mesulergine-labelling to the rat choroid plexus. [(3)H]mesulergine-labelled sites had pharmacological properties different from, at the time, known or purported 5-HT receptors. In spite of similarities with 5-HT2 binding, the new binding site was called 5-HT1C because of its very high affinity for 5-HT itself. Within the following 10 years, the 5-HT1CR (later named 5-HT2C) was extensively characterised pharmacologically, anatomically and functionally: it was one of the first 5-HT receptors to be sequenced and cloned. The 5-HT2CR is a GPCR, with a very complex gene structure. It constitutes a rarity in the GPCR family: many 5-HT2CR variants exist, especially in humans, due to RNA editing, in addition to a few 5-HT2CR splice variants. Intense research led to therapeutically active 5-HT2C receptor ligands, both antagonists (or inverse agonists) and agonists: keeping in mind that a number of antidepressants and antipsychotics are 5-HT2CR antagonists/inverse agonists. Agomelatine, a 5-HT2CR antagonist is registered for the treatment of major depression. The agonist Lorcaserin is registered for the treatment of aspects of obesity and has further potential in addiction, especially nicotine/ smoking

  20. 5-HT7 receptor modulators: Amino groups attached to biphenyl scaffold determine functional activity.

    PubMed

    Kim, Youngjae; Park, Hyeri; Lee, Jeongeun; Tae, Jinsung; Kim, Hak Joong; Min, Sun-Joon; Rhim, Hyewhon; Choo, Hyunah

    2016-11-10

    5-HT7 receptor (5-HT7R) agonists and antagonists have been reported to be used for treatment of neuropathic pain and depression, respectively. In this study, as a novel scaffold for 5-HT7R modulators, we designed and prepared a series of biphenyl-3-yl-methanamine derivatives with various amino groups. Evaluation of functional activities as well as binding affinities of the title compounds identified partial agonists (EC50 = 0.55-3.2 μM) and full antagonists (IC50 = 5.57-23.1 μM) depending on the amino substituents. Molecular docking study suggested that the ligand-based switch in functional activity from agonist to antagonist results from the size of the amino groups and thereby different binding modes to 5-HT7R. In particular, interaction of the ligand with Arg367 of 5-HT7R is shown to differentiate agonists and antagonists. In the pharmacophore model study, two distinct pharmacophore models can tell whether a ligand is an agonist or an antagonist. Taken together, this study provides valuable information for designing novel compounds with selective agonistic or antagonistic properties against 5-HT7R.

  1. A new class of arylpiperazine derivatives: the library synthesis on SynPhase lanterns and biological evaluation on serotonin 5-HT(1A) and 5-HT(2A) receptors.

    PubMed

    Zajdel, Paweł; Subra, Gilles; Bojarski, Andrzej J; Duszyńska, Beata; Pawłowski, Maciej; Martinez, Jean

    2004-01-01

    An efficient solid-supported method for the synthesis of a new class of arylpiperazine derivatives containing amino acid residues has been developed. A 72-membered library was synthesized on SynPhase Lanterns functionalized by a BAL linker. A one-pot cleavage/cyclization step of aspartic and glutamic acid derivatives yielded succinimide- and pyroglutamyl-containing ligands (chemsets 9 and 10). The library representatives under study showed different levels of affinity for 5-HT(1A) and 5-HT(2A) receptors (estimated K(i) = 24-4000 and 1-2130 nM, respectively). Several dual 5-HT(1A)/5-HT(2A) ligands were found, of which two (9(3,3) and 9(3,5)) displayed high 5-HT(2A) affinity comparable to that of the reference drug ritanserin. A set of individual fragment contributions for the prediction of 5-HT(1A) and 5-HT(2A) affinity of all the library members were defined on the basis of the Free-Wilson analysis of 26 compounds. An alkylarylpiperazine fragment had essentially the same impact on the affinity for both receptors, whereas different terminal amide fragments were preferred by 5-HT(1A) (chemset 17, R(2) = adamantyl) and 5-HT(2A) (chemset 9, R(2) = norborn-2-ylmethyl) binding sites.

  2. Rigidized 1-aryl sulfonyl tryptamines: synthesis and pharmacological evaluation as 5-HT6 receptor ligands.

    PubMed

    Nirogi, Ramakrishna; Dwarampudi, Adireddy; Kambhampati, Ramasastry; Bhatta, Venugopalarao; Kota, Laxman; Shinde, Anil; Badange, Rajesh; Jayarajan, Pradeep; Bhyrapuneni, Gopinadh; Dubey, P K

    2011-08-01

    A series of N(1)-arylsulfonyl-3-(pyrrolidin-3-yl)-1H-indole and N(1)-arylsulfonyl-3-(4-chloro-2,5-dihydro-1H-pyrrol-3-yl)-1H-indole derivatives (tryptamine derivatives with rigidized side chain) have been prepared and tested for their binding affinity to 5-HT(6) receptor. Several compounds displayed potent binding affinity for the 5-HT(6) receptor when tested in in vitro binding assay. The primary SAR indicates that rigidification of dimethylamino alkyl chain at C(3) of indole carbon maintains the binding affinity to 5-HT(6)R. The lead compound N(1)-benzenesulfonyl-3-(4-chloro-1-methyl-2,5-dihydro-1H-pyrrol-3-yl)-1H-indole, 10a (K(b)=0.1 nM) has shown excellent in vitro affinity and was active in animal models of cognition like NORT and water maze.

  3. Aryl biphenyl-3-ylmethylpiperazines as 5-HT7 receptor antagonists.

    PubMed

    Kim, Jeeyeon; Kim, Youngjae; Tae, Jinsung; Yeom, Miyoung; Moon, Bongjin; Huang, Xi-Ping; Roth, Bryan L; Lee, Kangho; Rhim, Hyewhon; Choo, Il Han; Chong, Youhoon; Keum, Gyochang; Nam, Ghilsoo; Choo, Hyunah

    2013-11-01

    The 5-HT7 receptor (5-HT7 R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5-HT7 R antagonist SB-269970 exhibited antidepressant-like activity, whereas systemic administration of the 5-HT7 R agonist AS-19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5-HT7 R antagonists or agonists, aryl biphenyl-3-ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5-HT7 R. Among the synthesized compounds, 1-([2'-methoxy-(1,1'-biphenyl)-3-yl]methyl)-4-(2-methoxyphenyl)piperazine (28) was the best binder to the 5-HT7 R (pKi =7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5-HT7 R over other serotonin receptor subtypes, such as 5-HT1 R, 5-HT2 R, 5-HT3 R, and 5-HT6 R. In a molecular modeling study, the 2-methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function.

  4. Synthesis and characterization of photoaffinity probes that target the 5-HT3 receptor.

    PubMed

    Jack, Thomas; Ruepp, Marc-David; Thompson, Andrew J; Mühlemann, Oliver; Lochner, Martin

    2014-01-01

    The 5-HT3 receptor is one of several ion channels responsible for the transmission of nerve impulses in the peripheral and central nervous systems. Until now, it has been difficult to characterize transmembrane receptors with classical structural biology approaches like X-ray crystallography. The use of photoaffinity probes is an alternative approach to identify regions in the protein where small molecules bind. To this end, we present two photoaffinity probes based on granisetron, a well known antagonist of the 5-HT3 receptor. These new probes show nanomolar binding affinity for the orthosteric binding site. In addition, we investigated their reactivity using irradiation experiments.

  5. Biochemical profile of YM992, a novel selective serotonin reuptake inhibitor with 5-HT2A receptor antagonistic activity.

    PubMed

    Hatanaka, K; Nomura, T; Hidaka, K; Takeuchi, H; Yatsugi, S; Fujii, M; Yamaguchi, T

    1996-01-01

    YM992, (S)-2-[[(7-fluoro-4-indanyl)oxy]methyl]morpholine monohydrochloride, exhibited the biochemical profile of a selective serotonin (5-HT) reuptake inhibitor (SSRI) with 5-HT2A receptor antagonistic activity. YM922 showed the same high affinity as fluoxetine against the 5-HT reuptake site (Ki = 21 nM) and a similar affinity to that of crazodone against the 5-HT2A receptor (Ki = 86 nM). In other receptor binding studies, an affinity for the adrenergic alpha 1 receptor (Ki = 200 nM) and 5-HT2C receptor (Ki = 680 nM) was observed. In a monoamine uptake study, YM992 showed a selective 5-HT uptake inhibition (IC50 = 0.15 microM), but only very weakly inhibited both noradrenaline (NA) and dopamine (DA) uptake (IC50 = 3.1 microM (NA), > 10 microM (DA)). YM992 was also found to potently inhibit the aggregation of human platelets (IC50 = 1.9 microM), revealing antagonistic activity for the 5-HT2A receptor in vitro. Enhanced serotonergic neurotransmission, in particular that mediated by the 5-HT1A receptor, has recently been reported to be important in the long-term treatment of depressive disorders with antidepressants. In addition, some 5-HT1A receptor-mediated responses are known to be potentiated by co-administration of 5-HT2A receptor antagonists. Thus, YM992, having both selective 5-HT reuptake inhibition and 5-HT2A antagonistic activity, might show potent therapeutic activity as a novel antidepressant in comparison with conventional SSRIs.

  6. On the role of brain 5-HT7 receptor in the mechanism of hypothermia: comparison with hypothermia mediated via 5-HT1A and 5-HT3 receptor.

    PubMed

    Naumenko, Vladimir S; Kondaurova, Elena M; Popova, Nina K

    2011-12-01

    Intracerebroventricular administration of selective agonist of serotonin 5-HT(7) receptor LP44 (4-[2-(methylthio)phenyl]-N-(1,2,3,4-tetrahydro-1-naphthalenyl)-1-pyperasinehexanamide hydrochloride; 10.3, 20.5 or 41.0 nmol) produced considerable hypothermic response in CBA/Lac mice. LP44-induced (20.5 nmol) hypothermia was significantly attenuated by the selective 5-HT(7) receptor antagonist SB 269970 (16.1 fmol, i.c.v.) pretreatment. At the same time, intraperitoneal administration of LP44 in a wide range of doses 1.0, 2.0 or 10.0 mg/kg (2.0, 4.0, 20.0 μmol/kg) did not cause considerable hypothermic response. These findings indicate the implication of central, rather than peripheral 5-HT(7) receptors in the regulation of hypothermia. The comparison of LP44-induced (20.5 nmol) hypothermic reaction in eight inbred mouse strains (DBA/2J, CBA/Lac, C57BL/6, BALB/c, ICR, AKR/J, C3H and Asn) was performed and a significant effect of genotype was found. In the same eight mouse strains, functional activity of 5-HT(1A) and 5-HT(3) receptors was studied. The comparison of hypothermic responses produced by 5-HT(7) receptor agonist LP44 (20.5 nmol, i.c.v.) and 5-HT(1A) receptor agonist 8-OH-DPAT 1.0 mg/kg, i.p. (3.0 μmol/kg), 5-HT(3) receptor agonist m-CPBG (40.0 nmol, i.c.v.) did not reveal considerable interstrain correlations between 5-HT(7) and 5-HT(1A) or 5-HT(3) receptor-induced hypothermia. The selective 5-HT(7) receptor antagonist SB 269970 (16.1 fmol, i.c.v.) failed to attenuate the hypothermic effect of 8-OH-DPAT 1.0 mg/kg, i.p. (3.0 μmol/kg) and m-CPBG (40.0 nmol, i.c.v.) indicating that the brain 5-HT(7) receptor is not involved in the hypothermic effects of 8-OH-DPAT or m-CPBG. The obtained results suggest that the central 5-HT(7) receptor plays an essential role in the mediation of thermoregulation independent of 5-HT(1A) and 5-HT(3) receptors.

  7. Mice with compromised 5-HTT function lack phosphotyrosine-mediated inhibitory control over prefrontal 5-HT responses.

    PubMed

    Goodfellow, Nathalie M; Sargin, Derya; Ansorge, Mark S; Gingrich, Jay A; Lambe, Evelyn K

    2014-04-23

    The activity of the prefrontal cortex is essential for normal emotional processing and is strongly modulated by serotonin (5-HT). Yet, little is known about the regulatory mechanisms that control the activity of the prefrontal 5-HT receptors. Here, we found and characterized a deregulation of prefrontal 5-HT receptor electrophysiological signaling in mouse models of disrupted serotonin transporter (5-HTT) function, a risk factor for emotional and cognitive disturbances. We identified a novel tyrosine kinase-dependent mechanism that regulates 5-HT-mediated inhibition of prefrontal pyramidal neurons. We report that mice with compromised 5-HTT, resulting from either genetic deletion or brief treatment with selective serotonin reuptake inhibitors during development, have amplified 5-HT1A receptor-mediated currents in adulthood. These greater inhibitory effects of 5-HT are accompanied by enhanced downstream coupling to Kir3 channels. Notably, in normal wild-type mice, we found that these larger 5-HT1A responses can be mimicked through inhibition of Src family tyrosine kinases. By comparison, in our 5-HTT mouse models, the larger 5-HT1A responses were rapidly reduced through inhibition of tyrosine phosphatases. Our findings implicate tyrosine phosphorylation in regulating the electrophysiological effects of prefrontal 5-HT1A receptors with implications for neuropsychiatric diseases associated with emotional dysfunction, such as anxiety and depressive disorders.

  8. Molecular imaging of the 5-HT(1A) receptor in relation to human cognition.

    PubMed

    Borg, Jacqueline

    2008-12-16

    Animal studies and pharmacological studies in man have suggested that the serotonin 5-HT(1A) receptor may serve as a biomarker for cognitive functioning and a target for treatment of cognitive impairment. Consistent findings in man have nonetheless hitherto remained sparse. Positron emission tomography (PET) imaging of the 5-HT(1A) receptor in patients with Alzheimer's disease, schizophrenia and depression implicate an alteration in 5-HT(1A) receptor binding compared to control subjects, but it is yet unknown whether these alterations are related to the cognitive impairment associated with these disorders. Pharmacological challenge studies using 5-HT(1A) agonism and antagonism to manipulate the serotonin system support involvement of the 5-HT(1A) receptor in human cognition, mainly in verbal memory functioning. However, the effect varies across studies and it remains unclear if the 5-HT(1A) receptor serves as a validated target for treatment of cognitive deficits. This lack of confirmation of experimental preclinical data, calls for increased efforts in translational research. Molecular imaging techniques such as PET, holds the potential to facilitate translational neuroscience by confirming observations from animal models in man, and aid development of validated animal models of use for advancement of pharmacological treatment. Furthermore, in combination with molecular genetics, molecular imaging may suggest novel strategies for prevention and intervention, based on an understanding of the molecular mechanisms involved in disease pathogenesis of major neuropsychiatric disorder and associated cognitive impairment.

  9. Pharmacological profile of lurasidone, a novel antipsychotic agent with potent 5-hydroxytryptamine 7 (5-HT7) and 5-HT1A receptor activity.

    PubMed

    Ishibashi, Tadashi; Horisawa, Tomoko; Tokuda, Kumiko; Ishiyama, Takeo; Ogasa, Masaaki; Tagashira, Rie; Matsumoto, Kenji; Nishikawa, Hiroyuki; Ueda, Yoko; Toma, Satoko; Oki, Hitomi; Tanno, Norihiko; Saji, Ikutaro; Ito, Akira; Ohno, Yukihiro; Nakamura, Mitsutaka

    2010-07-01

    Lurasidone [(3aR,4S,7R,7aS)-2-[(1R,2R)-2-[4-(1,2-benzisothiazol-3-yl)piperazin-1-ylmethyl]cyclohexylmethyl]hexahydro-4,7-methano-2H-isoindole-1,3-dione hydrochloride; SM-13496] is an azapirone derivative and a novel antipsychotic candidate. The objective of the current studies was to investigate the in vitro and in vivo pharmacological properties of lurasidone. Receptor binding affinities of lurasidone and several antipsychotic drugs were tested under comparable assay conditions using cloned human receptors or membrane fractions prepared from animal tissue. Lurasidone was found to have potent binding affinity for dopamine D(2), 5-hydroxytryptamine 2A (5-HT(2A)), 5-HT(7), 5-HT(1A), and noradrenaline alpha(2C) receptors. Affinity for noradrenaline alpha(1), alpha(2A), and 5-HT(2C) receptors was weak, whereas affinity for histamine H(1) and muscarinic acetylcholine receptors was negligible. In vitro functional assays demonstrated that lurasidone acts as an antagonist at D(2) and 5-HT(7) receptors and as a partial agonist at the 5-HT(1A) receptor subtype. Lurasidone showed potent effects predictive of antipsychotic activity, such as inhibition of methamphetamine-induced hyperactivity and apomorphine-induced stereotyped behavior in rats, similar to other antipsychotics. Furthermore, lurasidone had only weak extrapyramidal effects in rodent models. In animal models of anxiety disorders and depression, treatment with lurasidone was associated with significant improvement. Lurasidone showed a preferential effect on the frontal cortex (versus striatum) in increasing dopamine turnover. Anti-alpha(1)-noradrenergic, anticholinergic, and central nervous system (CNS) depressant actions of lurasidone were also very weak. These results demonstrate that lurasidone possesses antipsychotic activity and antidepressant- or anxiolytic-like effects with potentially reduced liability for extrapyramidal and CNS depressant side effects.

  10. Isolation of the serotoninergic 5-HT4(e) receptor from human heart and comparative analysis of its pharmacological profile in C6-glial and CHO cell lines

    PubMed Central

    Mialet, Jeanne; Berque-Bestel, Isabelle; Eftekhari, Pierre; Gastineau, Monique; Giner, Mireille; Dahmoune, Yamina; Donzeau-Gouge, Patrick; Hoebeke, Johan; Langlois, Michel; Sicsic, Sames; Fischmeister, Rodolphe; Lezoualc'h, Frank

    2000-01-01

    RT–PCR technique was used to clone the human 5-HT4(e) receptor (h5-HT4(e)) from heart atrium. We showed that this h5-HT4(e) receptor splice variant is restricted to brain and heart atrium. Recombinant h5-HT4(e) receptor was stably expressed in CHO and C6-glial cell lines at 347 and 88 fmol mg−1 protein, respectively. Expression of h5-HT4(e) receptors at the cell membrane was confirmed by immunoblotting. The receptor binding profile, determined by competition with [3H]-GR113808 of a number of 5-HT4 ligands, was consistent with that previously reported for other 5-HT4 receptor isoforms. Surprisingly, we found that the rank order of potencies (EC50) of 5-HT4 agonists obtained from adenylyl cyclase functional assays was inversely correlated to their rank order of affinities (Ki) obtained from binding assays. Furthermore, EC50 values for 5-HT, renzapride and cisapride were 2 fold lower in C6-glial cells than in CHO cells. ML10302 and renzapride behaved like partial agonists on the h5-HT4(e) receptor. These results are in agreement with the reported low efficacy of the these two compounds on L-type Ca2+ currents and myocyte contractility in human atrium. A constitutive activity of the h5-HT4(e) receptor was observed in CHO cells in the absence of any 5-HT4 ligand and two 5-HT4 antagonists, GR113808 and ML10375, behaved as inverse agonists. These data show that the h5-HT4(e) receptor has a pharmacological profile which is close to the native h5-HT4 receptor in human atrium with a functional potency which is dependent on the cellular context in which the receptor is expressed. PMID:10683202

  11. Behavioural evidence for a functional interaction between central 5-HT2 and 5-HT1A receptors.

    PubMed Central

    Backus, L. I.; Sharp, T.; Grahame-Smith, D. G.

    1990-01-01

    1. The possibility of 5-HT2 receptor modulation of central 5-HT1A receptor function has been examined using the 5-hydroxytryptamine (5-HT) behavioural syndrome induced by 5-HT1A receptor active drugs in rats. 2. The 5-HT2/5-HTIC antagonist ritanserin (0.1-2 mg kg-1) increased the 5-HT behavioural syndrome induced by submaximally effective doses of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and gepirone. 3. Pretreatment with the 5-HT2/5-HT1C antagonist ICI 170,809 (0.25-5 mg kg-1) also enhanced the behavioural syndrome induced by 8-OH-DPAT or 5-MeODMT. 4. The 5-HT2/alpha 1-adrenoceptor antagonist ketanserin in a low dose (0.25 mg kg-1) significantly increased the 5-HT behavioural syndrome induced by 8-OH-DPAT or 5-MeODMT, while in a higher dose (2.5 mg kg-1) this drug decreased the response. Experiments with prazosin indicate that the higher dose of ketanserin might reduce the 5-HT behavioural syndrome through blockade of alpha 1-adrenoceptors. 5. Ritanserin and ICI 170,809 had no effect on apomorphine-induced stereotypy or hyperactivity, indicating that these drugs do not produce non-specific behavioural activation. 6. Ritanserin and ICI 170,809 inhibited quipazine-induced wet dog shakes at doses similar to those enhancing the 5-HT behavioural syndrome. 7. We suggest that ritanserin, ICI 170,809 and ketanserin enhance 5-HT1A agonist-induced behaviour through blockade of an inhibitory 5-HT2 receptor regulating or coupled to 5-HT1A receptor-mediated function. PMID:2145051

  12. Serotonin transporter binding after recovery from bulimia nervosa

    PubMed Central

    Pichika, Rama; Buchsbaum, Monte S.; Bailer, Ursula; Hoh, Carl; DeCastro, Alex; Buchsbaum, Bradley R.; Kaye, Walter

    2011-01-01

    Objective Physiological and pharmacological studies indicate that altered brain serotonin (5-HT) activity could contribute to a susceptibility to develop appetitive and behavioural alterations that are characteristic of bulimia nervosa (BN). Methods Eight individuals recovered from BN (REC BN) and eight healthy control women were scanned with [11C]DASB and positron emission tomography imaging of the 5-HT transporter (5-HTT). Logan graphical analysis was applied and parametric binding potential (BPnon displaceable (ND)) images were generated. Voxel-by-voxel t-tests and a region of interest (ROI) analysis were conducted. Results REC BN had significantly lower [11C]DASB BPND in midbrain, superior and inferior cingulate and significantly higher [11C]DASB BPND in anterior cingulate and superior temporal gyrus in the voxel based analysis. ROI analysis indicated lower [11C]DASB BPND in midbrain (p=.07), containing the dorsal raphe, in REC BN, consistent with our earlier studies. Discussion These preliminary findings of a small scale study confirm and extend previous data suggesting that ill and recovered BN have altered 5-HTT measures, which potentially contribute to BN symptomology and/or differential responses to medication. PMID:21671458

  13. 5-HT spatial distribution imaging with multiphoton excitation of 5-HT correlative visible fluorescence in live cells

    NASA Astrophysics Data System (ADS)

    Zhang, Zhihong; Zeng, Shaoqun; Liu, Yafeng; Zhou, Wei; Chen, Tongsheng; Luo, Qingming

    2002-04-01

    The autofluorescence of 5-Hydroxytryptamine (5-HT) loaded rat mucosal mast cells (RBL-2H3 cells) is imaged with multiphoton excitation laser scanning microscope (MPELSM). 5-HT correlative visible fluorescence (Fco-vis) excited with 740-nm multiphoton excitation is observed in live cells for the first time, and the generating mechanism of 5-HT Fco-vis is studied. The spatial distribution of 5-HT in live cells is imaged at high spatial resolution in our experiment, which provides a new way to study the correlation between 5-HT spatial distribution and content, and the cellular functional state in live tissue or cells.

  14. Similar anxiolytic effects of agonists targeting serotonin 5-HT1A or cannabinoid CB receptors on zebrafish behavior in novel environments

    PubMed Central

    Connors, Kristin A.; Valenti, Theodore W.; Lawless, Kelly; Sackerman, James; Onaivi, Emmanuel S.; Brooks, Bryan W.; Gould, Georgianna G.

    2014-01-01

    The discovery that selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine are present and bioaccumulate in aquatic ecosystems have spurred studies of fish serotonin transporters (SERTs) and changes in SSRI-sensitive behaviors as adverse outcomes relevant for risk assessment. Many SSRIs also act at serotonin 5-HT1A receptors. Since capitolizing on this action may improve treatments of clinical depression and other psychiatric disorders, novel multimodal drugs that agonize 5-HT1A and block SERT were introduced. In mammals both 5-HT1A and CB agonists, such as buspirone and WIN55,212-2, reduce anxious behaviors. Immunological and behavioral evidence suggests that 5-HT1A-like receptors may function similarly in zebrafish (Danio rerio), yet their pharmacological properties are not well characterized. Herein we compared the density of [3H] 8-hydroxy-2-di-n-propylamino tetralin (8-OH-DPAT) binding to 5-HT1A-like sites in the zebrafish brain, to that of simalarly Gαi/o-coupled cannabinoid receptors. [3H] 8-OH-DPAT specific binding was 176 ± 8, 275 ± 32, and 230 ± 36 fmol/mg protein in the hypothalamus, optic tectum, and telencephalon. [3H] WIN55,212-2 binding density was higher in those same brain regions at 6 ± 0.3, 5.5 ± 0.4 and 7.3 ± 0.3 pm/mg protein. The aquatic light-dark plus maze was used to examine behavioral effects of 5-HT1A and CB receptor agonists on zebrafish novelty-based anxiety. With acute exposure to the 5-HT1A partial-agonist buspirone (50 mg/L), or dietary exposure to WIN55,212-2 (7 μg/week) zebrafish spent more time in and/or entered white arms more often than controls (p < 0.05). Acute exposure to WIN55,212-2 at 0.5-50 mg/L, reduced mobility. These behavioral findings suggest that azipirones, like cannabinoid agonists, have anxiolytic and/or sedative properties on fish in novel environments. These observations highlight the need to consider potential ecological risks of azapirones and multimodal antidepressants in the future. PMID

  15. Compositions and methods related to serotonin 5-HT1A receptors

    DOEpatents

    Mukherjee, Jogeshwar [Irvine, CA; Saigal, Neil [Fresno, CA; Saigal, legal representative, Harsh

    2012-09-25

    Contemplated substituted arylpiperazinyl compounds, and most preferably .sup.18F-Mefway, exhibit desirable in vitro and in vivo binding characteristics to the 5-HT1A receptor. Among other advantageous parameters, contemplated compounds retain high binding affinity, display optimal lipophilicity, and are radiolabeled efficiently with .sup.18F-fluorine in a single step. Still further, contemplated compounds exhibit high target to non-target ratios in receptor-rich regions both in vitro and in vivo, and selected compounds can be effectively and sensitively displaced by serotonin, thus providing a quantitative tool for measuring 5-HT1A receptors and serotonin concentration changes in the living brain.

  16. Compositions and methods related to serotonin 5-HT1A receptors

    DOEpatents

    Mukherjee, Jogeshwar; Saigal, Neil

    2010-06-08

    Contemplated substituted arylpiperazinyl compounds, and most preferably 18F-Mefway, exhibit desirable in vitro and in vivo binding characteristics to the 5-HT1A receptor. Among other advantageous parameters, contemplated compounds retain high binding affinity, display optimal lipophilicity, and are radiolabeled efficiently with 18F-fluorine in a single step. Still further, contemplated compounds exhibit high target to non-target ratios in receptor-rich regions both in vitro and in vivo, and selected compounds can be effectively and sensitively displaced by serotonin, thus providing a quantitative tool for measuring 5-HT1A receptors and serotonin concentration changes in the living brain.

  17. Compositions and methods related to serotonin 5-HT1A receptors

    DOEpatents

    Mukherjee, Jogeshwar; Saigal, Neil; Saigal, legal representative, Harsh

    2012-09-25

    Contemplated substituted arylpiperazinyl compounds, and most preferably 18F-Mefway, exhibit desirable in vitro and in vivo binding characteristics to the 5-HT1A receptor. Among other advantageous parameters, contemplated compounds retain high binding affinity, display optimal lipophilicity, and are radiolabeled efficiently with 18F-fluorine in a single step. Still further, contemplated compounds exhibit high target to non-target ratios in receptor-rich regions both in vitro and in vivo, and selected compounds can be effectively and sensitively displaced by serotonin, thus providing a quantitative tool for measuring 5-HT1A receptors and serotonin concentration changes in the living brain.

  18. The GR127935-sensitive 5-HT1 receptors mediating canine internal carotid vasoconstriction: resemblance to the 5-HT1B, but not to the 5-HT1D or 5-ht1F, receptor subtype

    PubMed Central

    Centurión, David; Sánchez-López, Araceli; De Vries, Peter; Saxena, Pramod R; Villalón, Carlos M

    2001-01-01

    This study has further investigated the pharmacological profile of the GR127935-sensitive 5-HT1 receptors mediating vasoconstriction in the internal carotid bed of anaesthetized vagosympathectomized dogs. One-minute intracarotid infusions of the agonists 5-hydroxytryptamine (5-HT; 0.1–10 μg min−1; endogenous ligand) and sumatriptan (0.3–10 μg min−1; 5-HT1B/1D), but not PNU-142633 (1–1000 μg min−1; 5-HT1D) or LY344864 (1–1000 μg min−1; 5-ht1F), produced dose-dependent decreases in internal carotid blood flow without changing blood pressure or heart rate. The responses to 5-HT were apparently resistant to blockade by i.v. administration of the antagonists SB224289 (300 μg kg−1; 5-HT1B), BRL15572 (300 μg kg−1; 5-HT1D) or ritanserin (100 μg kg−1; 5-HT2). In contrast, the responses to sumatriptan were antagonized by SB224289, but not by BRL15572. In the animals receiving SB224289, but not those receiving BRL15572, the subsequent administration of ritanserin abolished the 5-HT-induced vasoconstriction and unmasked a vasodilator component. Similarly, in ritanserin-treated animals, the subsequent administration of SB224289, but not BRL15572, completely blocked the 5-HT-induced vasoconstriction, revealing vasodilatation. In animals receiving initially BRL15572, the subsequent administration of SB224289 did not affect (except at 10 μg min−1) the vasoconstrictor responses to 5-HT. Notably, in animals pretreated with 1000 μg kg−1 of mesulergine, a 5-HT2/7 receptor antagonist, 5-HT produced a dose-dependent vasoconstriction, which was practically abolished by SB224289. After BRL15572, no further blockade was produced and the subsequent administration of ritanserin was similarly inactive. These results suggest that the GR127935-sensitive 5-HT1 receptors mediating canine internal carotid vasoconstriction resemble the 5-HT1B but not the 5-HT1D or 5-ht1F, receptor subtype. PMID:11226129

  19. Effect of Selective 5-HT6R Agonist on Expression of 5-HT Receptor and Neurotransmitter in Vascular Dementia Rats

    PubMed Central

    Yu, Haining; Chen, Tao; Zhou, Li; Tang, Jiyou

    2017-01-01

    Background 5-HT6 receptor (5-HT6R) has pluripotent roles regulating secretion of neurotransmitters. However, whether 5-HT6R is involved in the development of vascular dementia (VD) remains unclear. To evaluate the role and mechanism of 5-HT6R in VD, this study established a rat VD model to evaluate the effect of selective 5-HT6R agonist on the expression of 5-HT6R mRNA and neurotransmitter. Material/Methods Eighty healthy male SD rats (7 weeks old) were randomly assigned to sham, model, 5-HT6R agonist, and placebo groups (N=20 each). A rat VD model was generated by permeant bilateral ligation of the common carotid artery. 5-HT6R agonist, placebo, or saline were given intraperitoneally for 4 weeks. The Morris water maze was utilized to test learning and memory function. Brains were extracted to separate the cortex and hippocampal tissues, in which glutamate and γ-aminobutyric acid (GABA) levels were analyzed. mRNA and protein levels of 5-HT6R were determined by RT-PCR and immunohistochemistry (IHC), respectively. Results Model rats had longer escape latency and fewer crossing platform times. Contents of DA, Glu, GABA, and Ach were lowered in cortical and hippocampal tissues, and 5-HT6R expression was suppressed (p<0.05). The application of 5-HT6R agonist shortened escape latency and increased the number of passing through the platform. It also improved hippocampal CA1 neuronal damage and elevated DA, Glu, GABA, and Ach contents and expression of 5-HT6R. Expression of 5-HT6R was not different from the placebo group. Conclusions Selective 5-HT6R agonist can alleviate learning deficit of VD rats, possibly via improving neurotransmitter levels in brain regions. PMID:28196966

  20. Effects of the 5-HT receptor antagonists GR127935 (5-HT1B/1D) and MDL100907 (5-HT2A) in the consolidation of learning.

    PubMed

    Meneses, A; Terrón, J A; Hong, E

    1997-12-01

    We have previously reported that 5-HT1B/1D and 5-HT2A/2B/2C receptors play a role in learning and memory. The present investigation was devoted to analyze further in the autoshaping learning task: (1) the effects of the 5-HT1A/1B/1D receptor agonist, GR46611, the 5-HT1B/1D receptor antagonist, GR127935, and the selective 5-HT2A receptor antagonist, MDL100907. Consistent with a role of 5-HT1B/1D receptors in learning, the post-training injection of GR46611 (1-10 mg/kg) decreased the consolidation of learning whereas GR127935 (10 mg/kg) increased it; the effects of both drugs were reversed by PCA pretreatment. GR127935 abolished the decrease induced by GR46611, TFMPP and mCPP, whereas MDL100907 (0.1-3.0 mg/kg) had no effect by itself but abolished the effects of DOI, ketanserin and TFMPP and moderately inhibited the effects elicited by mCPP, 1-NP and mesulergine. Neither did GR127935 nor MDL100907 significantly modify the increase in the consolidation of learning induced by 8-OH-DPAT. Thus, the present findings suggest that stimulation of presynaptic 5-HT1B/1D receptors impairs the consolidation of learning whilst stimulation of 5-HT2A/2C receptors enhances it; the blockade of 5-HT2A receptors has no effects. In addition, 5-HT2 receptors seem to modulate this cognitive stage.

  1. (+)Lysergic acid diethylamide, but not its nonhallucinogenic congeners, is a potent serotonin 5HT1C receptor agonist

    SciTech Connect

    Burris, K.D.; Breeding, M.; Sanders-Bush, E. )

    1991-09-01

    Activation of central serotonin 5HT2 receptors is believed to be the primary mechanism whereby lysergic acid diethylamide (LSD) and other hallucinogens induce psychoactive effects. This hypothesis is based on extensive radioligand binding and electrophysiological and behavioral studies in laboratory animals. However, the pharmacological profiles of 5HT2 and 5HT1C receptors are similar, making it difficult to distinguish between effects due to activation of one or the other receptor. For this reason, it was of interest to investigate the interaction of LSD with 5HT1C receptors. Agonist-stimulated phosphoinositide hydrolysis in rat choroid plexus was used as a direct measure of 5HT1C receptor activation. (+)LSD potently stimulated phosphoinositide hydrolysis in intact choroid plexus and in cultures of choroid plexus epithelial cells, with EC50 values of 9 and 26 nM, respectively. The effect of (+)LSD in both systems was blocked by 5HT receptor antagonists with an order of activity consistent with interaction at 5HT1C receptors. Neither (+)-2-bromo-LSD nor lisuride, two nonhallucinogenic congeners of LSD, were able to stimulate 5HT1C receptors in cultured cells or intact choroid plexus. In contrast, lisuride, like (+)LSD, is a partial agonist at 5HT2 receptors in cerebral cortex slices and in NIH 3T3 cells transfected with 5HT2 receptor cDNA. The present finding that (+)LSD, but not its nonhallucinogenic congeners, is a 5HT1C receptor agonist suggests a possible role for these receptors in mediating the psychoactive effects of LSD.

  2. Galanin (1-15) enhances the antidepressant effects of the 5-HT1A receptor agonist 8-OH-DPAT: involvement of the raphe-hippocampal 5-HT neuron system.

    PubMed

    Millón, Carmelo; Flores-Burgess, Antonio; Narváez, Manuel; Borroto-Escuela, Dasiel O; Santín, Luis; Gago, Belen; Narváez, José Angel; Fuxe, Kjell; Díaz-Cabiale, Zaida

    2016-12-01

    Galanin N-terminal fragment (1-15) [GAL(1-15)] is associated with depression-related and anxiogenic-like effects in rats. In this study, we analyzed the ability of GAL(1-15) to modulate 5-HT1A receptors (5-HT1AR), a key receptor in depression. GAL(1-15) enhanced the antidepressant effects induced by the 5-HT1AR agonist 8-OH-DPAT in the forced swimming test. These effects were stronger than the ones induced by Galanin (GAL). This action involved interactions at receptor level since GAL(1-15) affected the binding characteristics and the mRNA levels of 5-HT1AR in the dorsal hippocampus and dorsal raphe. The involvement of the GALR2 was demonstrated with the GALR2 antagonist M871. Proximity ligation assay experiments indicated that 5-HT1AR are in close proximity with GALR1 and GALR2 in both regions and in raphe RN33B cells. The current results indicate that GAL(1-15) enhances the antidepressant effects induced by 8-OH-DPAT acting on 5-HT1AR operating as postjunctional or as autoreceptors. These results may give the basis for the development of drugs targeting potential GALR1-GALR2-5-HT1AR heteroreceptor complexes linked to the raphe-hippocampal 5-HT neurons for the treatment of depression.

  3. Pharmacological and genetic interventions in serotonin (5-HT)(2C) receptors to alter drug abuse and dependence processes.

    PubMed

    Filip, Małgorzata; Spampinato, Umberto; McCreary, Andrew C; Przegaliński, Edmund

    2012-10-02

    The present review provides an overview on serotonin (5-hydroxytryptamine; 5-HT)(2C) receptors and their relationship to drug dependence. We have focused our discussion on the impact of 5-HT(2C) receptors on the effects of different classes of addictive drugs, illustrated by reference to data using pharmacological and genetic tools. The neurochemical mechanism of the interaction between 5-HT(2C) receptors, with focus on the mesocorticolimbic dopaminergic system, and drugs of abuse (using cocaine as an example) is discussed. Finally, we integrate recent nonclinical and clinical research and information with marketed products possessing 5-HT(2C) receptor binding affinities. Accordingly, available nonclinical data and some clinical observations targeting 5-HT(2C) receptors may offer innovative translational strategies for combating drug dependence.This article is part of a Special Issue entitled: Brain Integration.

  4. Withdrawal from chronic cocaine up-regulates 5-HT1B receptors in the rat brain.

    PubMed

    Przegaliński, Edmund; Czepiel, Klaudia; Nowak, Ewa; Dlaboga, Daniel; Filip, Małgorzata

    2003-11-20

    In the present study we examined the effect of prolonged treatment with cocaine (a sensitization and discrimination paradigm) on the expression of serotonin (5-HT)(1B) receptors in rat brain structures using a quantitative autoradiographic analysis. To estimate the distribution of 5-HT(1B) receptors in several brain coronal sections, we used [N-methyl-(3)H]GR 125743, a 5-HT(1B/1D) receptor antagonist, in the presence of ketanserin (a drug used to block 5-HT(1D) receptors). The binding of [N-methyl-(3)H]GR 125743 in the areas containing dopamine cell bodies (the ventral tegmental area, the substantia nigra) and terminals (the nucleus accumbens shell and core, but not in the caudate-putamen) and in the subiculum of the hippocampus was increased after withdrawal from repeated cocaine in both the discrimination and the sensitization paradigms, either being effective as confirmed by behavioral experiments. Neither acute cocaine injection nor the psychostimulant challenge following its repeated administration affected the binding of [N-methyl-(3)H]GR 125743 in the above brain areas. Our results indicate that withdrawal from chronic cocaine induces up-regulation of 5-HT(1B) receptors in a number of rat brain structures.

  5. New insight into the therapeutic role of 5-HT1A receptors in central nervous system disorders.

    PubMed

    Ohno, Yukihiro

    2010-06-01

    The serotonergic system plays a crucial role in regulating psychoemotional, cognitive and motor functions in the central nervous system (CNS). Among 5-HT receptor subtypes, 5-HT(1A) receptors have long been implicated in the pathogenesis and treatment of anxiety and depressive disorders. 5-HT(1A) receptors function as both presynaptic (autoreceptor) and postsynaptic receptors in specific brain regions such as the limbic areas, septum and raphe nuclei. 5-HT(1A) receptors negatively regulate cAMP-dependent signal transduction and inhibit neuronal activity by opening G-protein-gated inwardly rectifying potassium channels. The therapeutic action of 5-HT(1A) agonists and their mechanism in alleviating anxiety and depressive disorders have been well documented. In addition, recent studies have revealed new insights into the therapeutic role of 5-HT(1A) receptors in treating various CNS disorders, including not only depressive disorders (e.g., delayed onset of action and refractory symptoms), but also schizophrenia (e.g., cognitive impairment and antipsychotic-induced extrapyramidal side effects) and Parkinson's disease (e.g., extrapyramidal motor symptoms and L-DOPA-induced dyskinesia). These lines of evidences encourage us to design new generation 5-HT(1A) ligands such as 5-HT(1A) agonists with greater potency, higher selectivity and improved pharmacokinetic properties, and 5-HT(1A) ligands which combine multiple pharmacological actions (e.g., inhibition of serotonin transporter, dopamine D(2) receptors and other 5-HT receptor subtypes). Such new 5-HT(1A) ligands may overcome clinical efficacy limitations and/or improve adverse reactions in current CNS therapies.

  6. Peripheral 5-HT1A and 5-HT7 Serotonergic Receptors Modulate Parasympathetic Neurotransmission in Long-Term Diabetic Rats

    PubMed Central

    Restrepo, Beatriz; Martín, María Luisa; San Román, Luis; Morán, Asunción

    2010-01-01

    We analyzed the modulation of serotonin on the bradycardia induced in vivo by vagal electrical stimulation in alloxan-induced long-term diabetic rats. Bolus intravenous administration of serotonin had a dual effect on the bradycardia induced either by vagal stimulation or exogenous Ach, increasing it at low doses and decreasing it at high doses of 5-hydroxytryptamine (5-HT), effect reproduced by 5-carboxamidotryptamine maleate (5-CT), a 5-HT1/7 agonist. The enhancement of the bradycardia at low doses of 5-CT was reproduced by 5-HT1A agonist 8-hydroxy-2-dipropylaminotetralin hydrobromide (8-OH-DPAT) and abolished by WAY-100,635, 5-HT1A antagonist. Pretreatment with 5-HT1 antagonist methiothepin blocked the stimulatory and inhibitory effect of 5-CT, whereas pimozide, 5-HT7 antagonist, only abolished 5-CT inhibitory action. In conclusion, long-term diabetes elicits changes in the subtype of the 5-HT receptor involved in modulation of vagally induced bradycardia. Activation of the 5-HT1A receptors induces enhancement, whereas attenuation is due to 5-HT7 receptor activation. This 5-HT dual effect occurs at pre- and postjunctional levels. PMID:21403818

  7. Possible roles of 5-HT in vein graft failure due to intimal hyperplasia 5-HT, nitric oxide and vein graft.

    PubMed

    Kodama, Akio; Itoh, Takeo; Komori, Kimihiro

    2014-02-01

    For vascular occlusive disease, an autologous vein graft is the most suitable conduit for arterial reconstruction. Intimal hyperplasia, resulting from the migration and proliferation of vascular smooth muscle cells, is a major obstacle to patency after vein grafting. The degree to which the function of nitric oxide (NO) in the vein graft is preserved has been reported to be associated with the magnitude of intimal hyperplasia. Serotonin (5-HT) is released from platelets in the vascular system and plays physiological roles in controlling the vascular tone. The subtype receptors contributing to the 5-HT-induced mechanical responses vary by vessel type (artery and vein) and among species (dogs, rabbits, rats, and so on). Recent studies have demonstrated that 5-HT induces vasoconstriction through the activation of 5-HT2A receptors in smooth muscle cells or vasodilatation through the activation of endothelial 5-HT1B receptors in arteries from various animals. However, the effects of 5-HT have not been clarified in grafted veins. We herein demonstrate the responses to 5-HT in un-operated veins and then autogenous vein grafts. Next, we describe the effects of chronic in vivo administration of Rho-kinase inhibitors and 5-HT2A receptor antagonists, both of which reduce the 5-HT-induced contraction and intimal hyperplasia in vein grafts. Further studies targeting 5-HT are required to evaluate its possible benefits for autologous vein grafts with respect to vasospasm, function, and patency.

  8. Convergence of melatonin and serotonin (5-HT) signaling at MT2/5-HT2C receptor heteromers.

    PubMed

    Kamal, Maud; Gbahou, Florence; Guillaume, Jean-Luc; Daulat, Avais M; Benleulmi-Chaachoua, Abla; Luka, Marine; Chen, Patty; Kalbasi Anaraki, Dina; Baroncini, Marc; Mannoury la Cour, Clotilde; Millan, Mark J; Prevot, Vincent; Delagrange, Philippe; Jockers, Ralf

    2015-05-01

    Inasmuch as the neurohormone melatonin is synthetically derived from serotonin (5-HT), a close interrelationship between both has long been suspected. The present study reveals a hitherto unrecognized cross-talk mediated via physical association of melatonin MT2 and 5-HT2C receptors into functional heteromers. This is of particular interest in light of the "synergistic" melatonin agonist/5-HT2C antagonist profile of the novel antidepressant agomelatine. A suite of co-immunoprecipitation, bioluminescence resonance energy transfer, and pharmacological techniques was exploited to demonstrate formation of functional MT2 and 5-HT2C receptor heteromers both in transfected cells and in human cortex and hippocampus. MT2/5-HT2C heteromers amplified the 5-HT-mediated Gq/phospholipase C response and triggered melatonin-induced unidirectional transactivation of the 5-HT2C protomer of MT2/5-HT2C heteromers. Pharmacological studies revealed distinct functional properties for agomelatine, which shows "biased signaling." These observations demonstrate the existence of functionally unique MT2/5-HT2C heteromers and suggest that the antidepressant agomelatine has a distinctive profile at these sites potentially involved in its therapeutic effects on major depression and generalized anxiety disorder. Finally, MT2/5-HT2C heteromers provide a new strategy for the discovery of novel agents for the treatment of psychiatric disorders.

  9. RU 24969-induced emesis in the cat - 5-HT1 sites other than 5-HT1A, 5-HT1B or 5-HT1C implicated

    NASA Technical Reports Server (NTRS)

    Lucot, James B.

    1990-01-01

    RU 24969 was administered s.c. to cats and found to elicit emesis with a maximally effective dose of 1.0 mg/kg 5-Methoxytryptamine was found to have lower efficacy and to produce a higher incidence of nonspecific effects while trifluoromethylphenylpiperizine (TFMPP) was devoid of emetic effects. The emesis elicited by 1.0 mg/kg of RU 24969 was not altered by pretreatment with phentolamine, haloperidol, yohimbine or (-)-propranolol, indicating that catecholamines played no role in this response. The emesis was prevented by metergoline and methysergide but not by ketanserin, cyproheptadine, mesulergine, ICS 205 930, methiothepin, trimethobenzamide or BMY 7378. An indirect argument is presented that implicates a role for 5-HT1D sites. This conclusion must remain tentative until drugs selective for this site are synthesized and tested. The emesis was also prevented by 8-hydroxy-2-(di-n-propylamine)tetralin (8-OH-DPAT), confirming that this drug has a general antiemetic effect in cats.

  10. Incubation of cocaine cue reactivity associates with neuroadaptations in the cortical serotonin (5-HT) 5-HT2C receptor (5-HT2CR) system.

    PubMed

    Swinford-Jackson, S E; Anastasio, N C; Fox, R G; Stutz, S J; Cunningham, K A

    2016-06-02

    Intensification of craving elicited by drug-associated cues during abstinence occurs over time in human cocaine users while elevation of cue reactivity ("incubation") is observed in rats exposed to extended forced abstinence from cocaine self-administration. Incubation in rodents has been linked to time-dependent neuronal plasticity in the medial prefrontal cortex (mPFC). We tested the hypothesis that incubation of cue reactivity during abstinence from cocaine self-administration is accompanied by lower potency and/or efficacy of the selective serotonin (5-HT) 5-HT2C​ receptor (5-HT2CR) agonist WAY163909 to suppress cue reactivity and a shift in the subcellular localization profile of the mPFC 5-HT2CR protein. We observed incubation of cue reactivity (measured as lever presses reinforced by the discrete cue complex) between Day 1 and Day 30 of forced abstinence from cocaine relative to sucrose self-administration. Pharmacological and biochemical analyses revealed that the potency of the selective 5-HT2CR agonist WAY163909 to suppress cue reactivity, the expression of synaptosomal 5-HT2CR protein in the mPFC, and the membrane to cytoplasmic expression of the 5-HT2CR in mPFC were lower on Day 30 vs. Day 1 of forced abstinence from cocaine self-administration. Incubation of cue reactivity assessed during forced abstinence from sucrose self-administration did not associate with 5-HT2CR protein expression in the mPFC. Collectively, these outcomes are the first indication that neuroadaptations in the 5-HT2CR system may contribute to incubation of cocaine cue reactivity.

  11. G-protein-linked serotonin receptors in mouse kidney exhibit identical properties to 5-HT1b receptors in brain

    SciTech Connect

    Ciaranello, R.D.; Tan, G.L.; Dean, R. )

    1990-03-01

    The serotonin 1b (5-HT1b) receptor is thought to mediate both pre- and postsynaptic actions of serotonin. Until recently 5-HT1b sites were thought to be present only in rodent brain. We now report the presence of high-affinity (125I)iodocyanopindolol ((125I) ICYP) binding sites in the mouse renal medulla with properties identical to those of brain 5-HT1b receptors. In vitro receptor autoradiography demonstrates that (125I)ICYP binding is highly localized to the outer stripe of the renal medulla. Association and dissociation kinetics, saturation analysis and competition displacement analyses indicate that renal medullary (125I)ICYP binding sites exhibit identical properties with brain 5-HT1b receptors. Incubation of renal medullary or brain membranes with guanylimidodiphosphate results in a decreased affinity of 5-HT1b sites for 5-HT and (125I)ICYP; this can be reversed by the addition of a purified mixture of G proteins (Gi/Go). Treatment of brain or kidney membranes with N-ethylmaleimide results in a decrease in 5-HT1b binding which can also be restored by reconstitution with purified G proteins. Adenylyl cyclase from renal medullary homogenates or minces can be stimulated more than 3-fold by forskolin and attenuated by 5-HT. These results indicate that mouse kidney contains high-affinity 5-HT1b receptors with identical properties to those found in brain. These are localized in the outer stripe of the renal medulla and are functionally coupled to adenylyl cyclase inhibitor (Gi) G-proteins.

  12. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2016-09-01

    Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects.

  13. The antimalarial drug proguanil is an antagonist at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2014-12-01

    Proguanil is an antimalarial prodrug that is metabolized to 4-chlorophenyl-1-biguanide (CPB) and the active metabolite cycloguanil (CG). These compounds are structurally related to meta-chlorophenyl biguanide (mCPBG), a 5-hydroxytryptamine 3 (5-HT3) receptor agonist. Here we examine the effects of proguanil and its metabolites on the electrophysiology and ligand-binding properties of human 5-HT3A receptors expressed in Xenopus oocytes and human embryonic kidney 293 cells, respectively. 5-HT3 receptor responses were reversibly inhibited by proguanil, with an IC50 of 1.81 μM. Competitive antagonism was shown by a lack of voltage-dependence, Schild plot (Kb = 1.70 μM), and radioligand competition (Ki = 2.61 μM) with the 5-HT3 receptor antagonist [(3)H]granisetron. Kinetic measurements (kon = 4.0 × 10(4) M(-1) s(-1) ; koff = 0.23 s(-1)) were consistent with a simple bimolecular reaction scheme with a Kb of 4.35 μM. The metabolites CG and CPB similarly inhibited 5-HT3 receptors as assessed by IC50 (1.48 and 4.36 μM, respectively), Schild plot (Kb = 2.97 and 11.4 μM), and radioligand competition (Ki = 4.89 and 0.41 μM). At higher concentrations, CPB was a partial agonist (EC50 = 14.1 μM; I/Imax = 0.013). These results demonstrate that proguanil competitively inhibits 5-HT3 receptors, with an IC50 that exceeds whole-blood concentrations following its oral administration. They may therefore be responsible for the occasional gastrointestinal side effects, nausea, and vomiting reported following its use. Clinical development of related compounds should therefore consider effects at 5-HT3 receptors as an early indication of possible unwanted gastrointestinal side effects.

  14. Positive and negative feedback learning and associated dopamine and serotonin transporter binding after methamphetamine

    PubMed Central

    Stolyarova, Alexandra; O’Dell, Steve J.; Marshall, John F.; Izquierdo, Alicia

    2014-01-01

    Learning from mistakes and prospectively adjusting behavior in response to reward feedback is an important facet of performance monitoring. Dopamine (DA) pathways play an important role in feedback learning and a growing literature has also emerged on the importance of serotonin (5HT) in reward learning, particularly during punishment or reward omission (negative feedback). Cognitive impairments resulting from psychostimulant exposure may arise from altered patterns in feedback learning, which in turn may be modulated by DA and 5HT transmission. We analyzed long-term, off-drug changes in learning from positive and negative feedback and associated striatal DA transporter (DAT) and frontocortical 5HT transporter (SERT) binding in rats pretreated with methamphetamine (mAMPH). Specifically, we assessed the reversal phase of pairwise visual discrimination learning in rats receiving single dose- (mAMPHsingle) vs. escalating-dose exposure (mAMPHescal). Using fine-grained trial-by-trial analyses, we found increased sensitivity to and reliance on positive feedback in mAMPH-pretreated animals, with the mAMPHsingle group showing more pronounced use of this type of feedback. In contrast, overall negative feedback sensitivity was not altered following any mAMPH treatment. In addition to validating the enduring effects of mAMPH on early reversal learning, we found more consecutive error commissions before the first correct response in mAMPH-pretreated rats. This behavioral rigidity was negatively correlated with subregional frontocortical SERT whereas positive feedback sensitivity negatively correlated with striatal DAT binding. These results provide new evidence for the overlapping, yet dissociable roles of DA and 5HT systems in overcoming perseveration and in learning new reward rules. PMID:24959862

  15. Positive and negative feedback learning and associated dopamine and serotonin transporter binding after methamphetamine.

    PubMed

    Stolyarova, Alexandra; O'Dell, Steve J; Marshall, John F; Izquierdo, Alicia

    2014-09-01

    Learning from mistakes and prospectively adjusting behavior in response to reward feedback is an important facet of performance monitoring. Dopamine (DA) pathways play an important role in feedback learning and a growing literature has also emerged on the importance of serotonin (5HT) in reward learning, particularly during punishment or reward omission (negative feedback). Cognitive impairments resulting from psychostimulant exposure may arise from altered patterns in feedback learning, which in turn may be modulated by DA and 5HT transmission. We analyzed long-term, off-drug changes in learning from positive and negative feedback and associated striatal DA transporter (DAT) and frontocortical 5HT transporter (SERT) binding in rats pretreated with methamphetamine (mAMPH). Specifically, we assessed the reversal phase of pairwise visual discrimination learning in rats receiving single dose- (mAMPHsingle) vs. escalating-dose exposure (mAMPHescal). Using fine-grained trial-by-trial analyses, we found increased sensitivity to and reliance on positive feedback in mAMPH-pretreated animals, with the mAMPHsingle group showing more pronounced use of this type of feedback. In contrast, overall negative feedback sensitivity was not altered following any mAMPH treatment. In addition to validating the enduring effects of mAMPH on early reversal learning, we found more consecutive error commissions before the first correct response in mAMPH-pretreated rats. This behavioral rigidity was negatively correlated with subregional frontocortical SERT whereas positive feedback sensitivity negatively correlated with striatal DAT binding. These results provide new evidence for the overlapping, yet dissociable roles of DA and 5HT systems in overcoming perseveration and in learning new reward rules.

  16. The serotonin 5-HT3 receptor: a novel neurodevelopmental target.

    PubMed

    Engel, Mareen; Smidt, Marten P; van Hooft, Johannes A

    2013-01-01

    Serotonin (5-hydroxytryptamine, 5-HT), next to being an important neurotransmitter, recently gained attention as a key-regulator of pre- and postnatal development in the mammalian central nervous system (CNS). Several receptors for 5-HT are expressed in the developing brain including a ligand-gated ion channel, the 5-HT3 receptor. Over the past years, evidence has been accumulating that 5-HT3 receptors are involved in the regulation of neurodevelopment by serotonin. Here, we review the spatial and temporal expression patterns of 5-HT3 receptors in the pre- and early postnatal rodent brain and its functional implications. First, 5-HT3 receptors are expressed on GABAergic interneurons in neocortex and limbic structures derived from the caudal ganglionic eminence. Mature inhibitory GABAergic interneurons fine-tune neuronal excitability and thus are crucial for the physiological function of the brain. Second, 5-HT3 receptors are expressed on specific glutamatergic neurons, Cajal-Retzius cells in the cortex and granule cells in the cerebellum, where they regulate morphology, positioning, and connectivity of the local microcircuitry. Taken together, the 5-HT3 receptor emerges as a potential key-regulator of network formation and function in the CNS, which could have a major impact on our understanding of neurodevelopmental disorders in which 5-HT plays a role.

  17. New arylpiperazinylalkyl derivatives of 8-alkoxy-purine-2,6-dione and dihydro[1,3]oxazolo[2,3-f]purinedione targeting the serotonin 5-HT1A /5-HT2A /5-HT7 and dopamine D2 receptors.

    PubMed

    Chłoń-Rzepa, Grażyna; Zagórska, Agnieszka; Bucki, Adam; Kołaczkowski, Marcin; Pawłowski, Maciej; Satała, Grzegorz; Bojarski, Andrzej J; Partyka, Anna; Wesołowska, Anna; Pękala, Elżbieta; Słoczyńska, Karolina

    2015-04-01

    To obtain potential antidepressants and/or antipsychotics, a series of new long-chain arylpiperazine derivatives of 8-alkoxy-purine-2,6-dione (10-24) and dihydro[1,3]oxazolo[2,3-f]purinedione (30-34) were synthesized and their serotonin (5-HT1A , 5-HT2A , 5-HT6 , 5-HT7 ) and dopamine (D2 ) receptor affinities were determined. The study allowed the identification of some potent 5-HT1A /5-HT7 /D2 ligands with moderate affinity for 5-HT2A sites. The binding mode of representative compounds from both chemical classes (11 and 31) in the site of 5-HT1A receptor was analyzed in computational studies. In functional in vitro studies, the selected compounds 15 and 16 showed antagonistic properties for the evaluated receptors. 8-Methoxy-7-{4-[4-(2-methoxyphenyl)-piperazin-1-yl]-butyl}-1,3-dimethyl-purine-2,6-dione (15) showed a lack of activity in terms and under the conditions of the forced swim, four plate and amphetamine-induced hyperactivity tests in mice, probably as a result of its high first pass effect in the liver.

  18. 5-HT7 receptors as modulators of neuronal excitability, synaptic transmission and plasticity: physiological role and possible implications in autism spectrum disorders

    PubMed Central

    Ciranna, Lucia; Catania, Maria Vincenza

    2014-01-01

    Serotonin type 7 receptors (5-HT7) are expressed in several brain areas, regulate brain development, synaptic transmission and plasticity, and therefore are involved in various brain functions such as learning and memory. A number of studies suggest that 5-HT7 receptors could be potential pharmacotherapeutic target for cognitive disorders. Several abnormalities of serotonergic system have been described in patients with autism spectrum disorder (ASD), including abnormal activity of 5-HT transporter, altered blood and brain 5-HT levels, reduced 5-HT synthesis and altered expression of 5-HT receptors in the brain. A specific role for 5-HT7 receptors in ASD has not yet been demonstrated but some evidence implicates their possible involvement. We have recently shown that 5-HT7 receptor activation rescues hippocampal synaptic plasticity in a mouse model of Fragile X Syndrome, a monogenic cause of autism. Several other studies have shown that 5-HT7 receptors modulate behavioral flexibility, exploratory behavior, mood disorders and epilepsy, which include core and co-morbid symptoms of ASD. These findings further suggest an involvement of 5-HT7 receptors in ASD. Here, we review the physiological roles of 5-HT7 receptors and their implications in Fragile X Syndrome and other ASD. PMID:25221471

  19. 5-HT7 receptors as modulators of neuronal excitability, synaptic transmission and plasticity: physiological role and possible implications in autism spectrum disorders.

    PubMed

    Ciranna, Lucia; Catania, Maria Vincenza

    2014-01-01

    Serotonin type 7 receptors (5-HT7) are expressed in several brain areas, regulate brain development, synaptic transmission and plasticity, and therefore are involved in various brain functions such as learning and memory. A number of studies suggest that 5-HT7 receptors could be potential pharmacotherapeutic target for cognitive disorders. Several abnormalities of serotonergic system have been described in patients with autism spectrum disorder (ASD), including abnormal activity of 5-HT transporter, altered blood and brain 5-HT levels, reduced 5-HT synthesis and altered expression of 5-HT receptors in the brain. A specific role for 5-HT7 receptors in ASD has not yet been demonstrated but some evidence implicates their possible involvement. We have recently shown that 5-HT7 receptor activation rescues hippocampal synaptic plasticity in a mouse model of Fragile X Syndrome, a monogenic cause of autism. Several other studies have shown that 5-HT7 receptors modulate behavioral flexibility, exploratory behavior, mood disorders and epilepsy, which include core and co-morbid symptoms of ASD. These findings further suggest an involvement of 5-HT7 receptors in ASD. Here, we review the physiological roles of 5-HT7 receptors and their implications in Fragile X Syndrome and other ASD.

  20. Pathways and Barriers for Ion Translocation through the 5-HT3A Receptor Channel

    PubMed Central

    Di Maio, Danilo; Chandramouli, Balasubramanian; Brancato, Giuseppe

    2015-01-01

    Pentameric ligand gated ion channels (pLGICs) are ionotropic receptors that mediate fast intercellular communications at synaptic level and include either cation selective (e.g., nAChR and 5-HT3) or anion selective (e.g., GlyR, GABAA and GluCl) membrane channels. Among others, 5-HT3 is one of the most studied members, since its first cloning back in 1991, and a large number of studies have successfully pinpointed protein residues critical for its activation and channel gating. In addition, 5-HT3 is also the target of a few pharmacological treatments due to the demonstrated benefits of its modulation in clinical trials. Nonetheless, a detailed molecular analysis of important protein features, such as the origin of its ion selectivity and the rather low conductance as compared to other channel homologues, has been unfeasible until the recent crystallization of the mouse 5-HT3A receptor. Here, we present extended molecular dynamics simulations and free energy calculations of the whole 5-HT3A protein with the aim of better understanding its ion transport properties, such as the pathways for ion permeation into the receptor body and the complex nature of the selectivity filter. Our investigation unravels previously unpredicted structural features of the 5-HT3A receptor, such as the existence of alternative intersubunit pathways for ion translocation at the interface between the extracellular and the transmembrane domains, in addition to the one along the channel main axis. Moreover, our study offers a molecular interpretation of the role played by an arginine triplet located in the intracellular domain on determining the characteristic low conductance of the 5-HT3A receptor, as evidenced in previous experiments. In view of these results, possible implications on other members of the superfamily are suggested. PMID:26465896

  1. Inflammation and peripheral 5-HT7 receptors: the role of 5-HT7 receptors in carrageenan induced inflammation in rats.

    PubMed

    Albayrak, Abdulmecit; Halici, Zekai; Cadirci, Elif; Polat, Beyzagul; Karakus, Emre; Bayir, Yasin; Unal, Deniz; Atasoy, Mustafa; Dogrul, Ahmet

    2013-09-05

    The aim of this study was: (1) to investigate possible role for 5-HT7 receptors in carrageenan induced inflammatory paw oedema in rats; (2) to determine the presence of 5-HT7 receptors in rat paw tissue; (3) to observe the effects of 5-HT7 receptor agonist and antagonist administration on inflammation; and (4) to determine a unique mechanism for inflammatory processes via 5-HT7 receptors. Effects of 5-HT7 receptor agonist, antagonist and indomethacin were investigated in carrageenan induced paw oedema in rats. Blood and tissue samples were collected and evaluated biochemically for serum cytokine levels, tissue oxidant-antioxidant balance and histopathologically for inflammatory cell accumulation. We performed Real Time PCR analyses for tissue 5-HT7 receptor and COX mRNA expressions. The 5-HT7 receptor agonist AS-19 exerted significant anti-inflammatory effect both alone and in combination with indomethacin. Antagonist, SB269970, did not affect inflammation alone but decreased the effects of agonist when co-administered. 5-HT7 mRNA levels were higher in the carrageenan group than healthy control. Carrageenan+indometacin group decreased the mRNA expression of 5-HT7 when compared to carrageenan group. While agonist administration decreased 5-HT7 mRNA expression when compared to carrageenan group. Agonist decreased paw COX expression. Agonist also decreased serum cytokine levels and tissue oxidative stress. In conclusion, this study demonstrated for the first time that 5-HT7 receptors are expressed in rat paw tissue and that this expression responds to inflammatory stimuli. The 5-HT7 receptor may be a promising new therapeutic target for prevention of inflammation and inflammatory disorders and may also provide a new glimpse into inflammation pathophysiology.

  2. AHR-16303B, a novel antagonist of 5-HT2 receptors and voltage-sensitive calcium channels

    SciTech Connect

    Barrett, R.J.; Appell, K.C.; Kilpatrick, B.F.; Proakis, A.G.; Nolan, J.C.; Walsh, D.A. )

    1991-01-01

    In vivo and in vitro methods were used to characterize AHR-16303B, a novel compound with antagonistic action at 5-HT2 receptors and voltage-sensitive calcium channels. The 5-HT2 receptor-antagonistic properties of AHR-16303B were demonstrated by inhibition of (a) (3H)ketanserin binding to rat cerebral cortical membranes (IC50 = 165 nM); (b) 5-hydroxytryptamine (5-HT)-induced foot edema in rats (minimum effective dose, (MED) = 0.32 mg/kg orally, p.o.); (c) 5-HT-induced vasopressor responses in spontaneously hypertensive rats (SHR) (ID50 = 0.18 mg/kg intravenously (i.v.), 1.8 mg/kg p.o.), (d) 5-HT-induced antidiuresis in rats (MED = 1 mg/kg p.o.), and (e) platelet aggregation induced by 5-HT + ADP (IC50 = 1.5 mM). The calcium antagonist properties of AHR-16303B were demonstrated by inhibition of (a) (3H)nimodipine binding to voltage-sensitive calcium channels on rabbit skeletal muscle membranes (IC50 = 15 nM), (b) KCl-stimulated calcium flux into cultured PC12 cells (IC50 = 81 nM), and (c) CaCl2-induced contractions of rabbit thoracic aortic strips (pA2 = 8.84). AHR-16303B had little or no effect on binding of radioligands to dopamine2 (DA2) alpha 1, alpha 2, H1, 5-HT1 alpha, beta 2, muscarinic M1, or sigma opioid receptors; had no effect on 5-HT3 receptor-mediated vagal bradycardia; and had only minor negative inotropic, chronotropic, and dromotropic effects on isolated guinea pig atria. In conscious SHR, 30 mg/kg p.o. AHR-16303B completely prevented the vasopressor responses to i.v. 5-HT, and decreased blood pressure (BP) by 24% 3 h after dosing.

  3. The phytocannabinoid, Δ9-tetrahydrocannabivarin, can act through 5-HT1A receptors to produce antipsychotic effects

    PubMed Central

    Cascio, Maria Grazia; Zamberletti, Erica; Marini, Pietro; Parolaro, Daniela; Pertwee, Roger G

    2015-01-01

    Background and Purpose This study aimed to address the questions of whether Δ9-tetrahydrocannabivarin (THCV) can (i) enhance activation of 5-HT1A receptors in vitro and (ii) induce any apparent 5-HT1A receptor-mediated antipsychotic effects in vivo. Experimental Approach In vitro studies investigated the effect of THCV on targeting by 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) of 5-HT1A receptors in membranes obtained from rat brainstem or human 5-HT1A CHO cells, using [35S]-GTPγS and 8-[3H]-OH-DPAT binding assays. In vivo studies investigated whether THCV induces signs of 5-HT1A receptor-mediated antipsychotic effects in rats. Key Results THCV (i) potently, albeit partially, displaced 8-[3H]-OH-DPAT from specific binding sites in rat brainstem membranes; (ii) at 100 nM, significantly enhanced 8-OH-DPAT-induced activation of receptors in these membranes; (iii) produced concentration-related increases in 8-[3H]-OH-DPAT binding to specific sites in membranes of human 5-HT1A receptor-transfected CHO cells; and (iv) at 100 nM, significantly enhanced 8-OH-DPAT-induced activation of these human 5-HT1A receptors. In phencyclidine-treated rats, THCV, like clozapine (i) reduced stereotyped behaviour; (ii) decreased time spent immobile in the forced swim test; and (iii) normalized hyperlocomotor activity, social behaviour and cognitive performance. Some of these effects were counteracted by the 5-HT1A receptor antagonist, WAY100635, or could be reproduced by the CB1 antagonist, AM251. Conclusions and Implications Our findings suggest that THCV can enhance 5-HT1A receptor activation, and that some of its apparent antipsychotic effects may depend on this enhancement. We conclude that THCV has therapeutic potential for ameliorating some of the negative, cognitive and positive symptoms of schizophrenia. PMID:25363799

  4. GABA and 5-HT chitosan nanoparticles decrease striatal neuronal degeneration and motor deficits during liver injury.

    PubMed

    Shilpa, J; Paulose, C S

    2014-07-01

    The metabolic alterations resulted from hepatic injury and cell loss lead to synaptic defects and neurodegeneration that undoubtedly contribute motor deficits. In the present study, GABA and 5-HT chitosan nanoparticles mediated liver cell proliferation influenced by growth factor and cytokines and neuronal survival in corpus striatum of partially hepatectomised rats was evaluated. Liver cell proliferation was initiated and progressed by the combined effect of increased expression of growth factor, insulin like growth factor-1 and decreased expressions of cytokines, tumor necrosis factor-α and Akt-1. This was confirmed by the extent of incorporation of thymidine analogue, BrdU, in the DNA of rapidly dividing cells. Inappropriate influx of compounds to corpus striatum resulting from incomplete metabolism elevated GABAB and 5-HT2A neurotransmissions compared to those treated with nanoparticles. This directly influenced cyclic AMP response element binding protein, glial cell derived neurotrophic factor and brain derived neurotrophic factor in the corpus striatum that facilitate neurogenesis, neuronal survival, development, differentiation and neuroprotection. Motor deficits due to liver injury followed striatal neuronal damage were scored by grid walk and rotarod studies, which confirmed the regain of motor activity by GABA and 5-HT chitosan nanoparticle treatment. The present study revealed the therapeutic significance of GABA and 5-HT chitosan nanoparticles in liver based diseases and related striatal neuronal damage that influenced by GABA and 5-HT.

  5. Signal transduction and functional selectivity of F15599, a preferential post-synaptic 5-HT1A receptor agonist

    PubMed Central

    Newman-Tancredi, A; Martel, J-C; Assié, M-B; Buritova, J; Lauressergues, E; Cosi, C; Heusler, P; Slot, L Bruins; Colpaert, FC; Vacher, B; Cussac, D

    2009-01-01

    Background and purpose: Activation of post-synaptic 5-HT1A receptors may provide enhanced therapy against depression. We describe the signal transduction profile of F15599, a novel 5-HT1A receptor agonist. Experimental approach: F15599 was compared with a chemical congener, F13714, and with (+)8-OH-DPAT in models of signal transduction in vitro and ex vivo. Key results: F15599 was highly selective for 5-HT1A receptors in binding experiments and in [35S]-GTPγS autoradiography of rat brain, where F15599 increased labelling in regions expressing 5-HT1A receptors. In cell lines expressing h5-HT1A receptors, F15599 more potently stimulated extracellular signal-regulated kinase (ERK1/2) phosphorylation, compared with G-protein activation, internalization of h5-HT1A receptors or inhibition of cAMP accumulation. F13714, (+)8-OH-DPAT and 5-HT displayed a different rank order of potency for these responses. F15599 stimulated [35S]-GTPγS binding more potently in frontal cortex than raphe. F15599, unlike 5-HT, more potently and efficaciously stimulated Gαi than Gαo activation. In rat prefrontal cortex (a region expressing post-synaptic 5-HT1A receptors), F15599 potently activated ERK1/2 phosphorylation and strongly induced c-fos mRNA expression. In contrast, in raphe regions (expressing pre-synaptic 5-HT1A receptors) F15599 only weakly or did not induce c-fos mRNA expression. Finally, despite its more modest affinity in vitro, F15599 bound to 5-HT1A receptors in vivo almost as potently as F13714. Conclusions and implications: F15599 showed a distinctive activation profiles for 5-HT1A receptor-mediated signalling pathways, unlike those of reference agonists and consistent with functional selectivity at 5-HT1A receptors. In rat, F15599 potently activated signalling in prefrontal cortex, a feature likely to underlie its beneficial effects in models of depression and cognition. PMID:19154445

  6. The Role of 5-HT2A, 5-HT2C and mGlu2 Receptors in the Behavioral Effects of Tryptamine Hallucinogens N,N-Dimethyltryptamine and N,N-Diisopropyltryptamine in Rats and Mice

    PubMed Central

    Carbonaro, Theresa M.; Eshleman, Amy J.; Forster, Michael J.; Cheng, Kejun; Rice, Kenner C.; Gatch, Michael B.

    2014-01-01

    Rationale: Serotonin 5-HT2A and 5-HT2C receptors are thought to be the primary pharmacological mechanisms for serotonin-mediated hallucinogenic drugs, but recently there has been interest in metabotropic glutamate (mGluR2) receptors as contributors to the mechanism of hallucinogens. Objective: The present study assesses the role of these 5-HT and glutamate receptors as molecular targets for two tryptamine hallucinogens, N,N-dimethyltryptamine (DMT) and N,N-diisopropyltryptamine (DiPT). Methods: Drug discrimination, head twitch and radioligand binding assays were used. A 5-HT2AR inverse agonist (MDL100907), 5-HT2CR antagonist (SB242084) and mGluR2/3 agonist (LY379268) were tested for their ability to attenuate the discriminative stimulus effects of DMT and DiPT; an mGluR2/3 antagonist (LY341495) was tested for potentiation. MDL100907 was used to attenuate head twitches induced by DMT and DiPT. Radioligand binding studies and inosital-1-phosphate (IP-1) accumulation were performed at the 5-HT2CR for DiPT. Results: MDL100907 fully blocked the discriminative stimulus effects of DMT, but only partially blocked DiPT. SB242084 partially attenuated the discriminative stimulus effects of DiPT, but produced minimal attenuation of DMT’s effects. LY379268 produced potent, but only partial blockade of the discriminative stimulus effects of DMT. LY341495 facilitated DMT- and DiPT-like effects. Both compounds elicited head twitches (DiPT>DMT) which were blocked by MDL1000907. DiPT was a low potency full agonist at 5-HT2CR in vitro. Conclusions: The 5-HT2AR likely plays a major role in mediating the effects of both compounds. 5-HT2C and mGluR2 receptors likely modulate the discriminative stimulus effects of both compounds to some degree. PMID:24985890

  7. Behavioral and neurochemical pharmacology of six psychoactive substituted phenethylamines: Mouse locomotion, rat drug discrimination and in vitro receptor and transporter binding and function

    PubMed Central

    Eshleman, Amy J.; Forster, Michael J.; Wolfrum, Katherine M.; Johnson, Robert A.; Janowsky, Aaron; Gatch, Michael B.

    2014-01-01

    Rationale Psychoactive substituted phenethylamines 2,5-dimethoxy-4-chlorophenethylamine (2C-C); 2,5-dimethoxy-4-methylphenethylamine (2C-D); 2,5-dimethoxy-4-ethylphenethylamine (2C-E); 2,5-dimethoxy-4-iodophenethylamine (2C-I); 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2) and 2,5-dimethoxy-4-chloroamphetamine (DOC) are used recreationally and may have deleterious side effects. Objectives This study compares behavioral effects and mechanisms of action of these substituted phenethylamines with those of hallucinogens and a stimulant. Methods The effects of these compounds on mouse locomotor activity and in rats trained to discriminate dimethyltryptamine, (−)DOM, (+)LSD, (±)MDMA and (S+)methamphetamine were assessed. Binding and functional activity of the phenethylamines at 5-HT1A, 5-HT2A, 5-HT2C receptors and monoamine transporters were assessed using cells heterologously expressing these proteins. Results The phenethylamines depressed mouse locomotor activity, although 2C-D and 2C-E stimulated activity at low doses. The phenethylamines except 2C-T-2 fully substituted for at least one hallucinogenic training compound but none fully substituted for (+)-methamphetamine. At 5-HT1A receptors, only 2C-T-2 and 2C-I were partial-to-full very low potency agonists. In 5-HT2A arachidonic acid release assays, the phenethylamines were partial to full agonists except 2C-I which was an antagonist. All compounds were full agonists at 5-HT2A and 5-HT2C receptor inositol phosphate assays. Only 2C-I had moderate affinity for, and very low potency at, the serotonin transporter. Conclusions The discriminative stimulus effects of 2C-C, 2C-D, 2C-E, 2C-I and DOC were similar to those of several hallucinogens but not methamphetamine. Additionally, the substituted phenethylamines were full agonists at 5-HT2A and 5-HT2C receptors, but for 2C-T-2, this was not sufficient to produce hallucinogenlike discriminative stimulus effects. Additionally, the 5-HT2A inositol phosphate pathway may

  8. The selective 5-HT2A receptor antagonist M100907 enhances antidepressant-like behavioral effects of the SSRI fluoxetine.

    PubMed

    Marek, Gerard J; Martin-Ruiz, Raul; Abo, Allyson; Artigas, Francesc

    2005-12-01

    The addition of low doses of atypical antipsychotic drugs, which saturate 5-HT(2A) receptors, enhances the therapeutic effect of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) in patients with major depression as well as treatment-refractory obsessive-compulsive disorder. The purpose of the present studies was to test the effects of combined treatment with a low dose of a highly selective 5-HT(2A) receptor antagonist (M100907; formerly MDL 100,907) and low doses of a SSRI using a behavioral screen in rodents (the differential-reinforcement-of low rate 72-s schedule of reinforcement; DRL 72-s) which previously has been shown to be sensitive both to 5-HT(2) antagonists and SSRIs. M100907 has a approximately 100-fold or greater selectivity at 5-HT(2A) receptors vs other 5-HT receptor subtypes, and would not be expected to appreciably occupy non-5-HT(2A) receptors at doses below 100 microg/kg. M100907 increased the reinforcement rate, decreased the response rate, and shifted the inter-response time distributions to the right in a pattern characteristic of antidepressant drugs. In addition, a positive synergistic interaction occurred when testing low doses of the 5-HT(2A) receptor antagonist (6.25-12.5 microg/kg) with clinically relevant doses of the SSRI fluoxetine (2.5-5 mg/kg), which both exerted minimal antidepressant-like effects by themselves. In vivo microdialysis study revealed that a low dose of M100907 (12.5 microg/kg) did not elevate extracellular 5-HT levels in the prefrontal cortex over those observed with fluoxetine alone (5 mg/kg). These results will be discussed in the context that the combined blockade of 5-HT(2A) receptors and serotonin transporters (SERT) may result in greater efficacy in treating neuropsychiatric syndromes than blocking either site alone.

  9. Pharmacological profile of the 5-HT-induced inhibition of cardioaccelerator sympathetic outflow in pithed rats: correlation with 5-HT1 and putative 5-ht5A/5B receptors

    PubMed Central

    Sánchez-López, Araceli; Centurión, David; Vázquez, Erika; Arulmani, Udayasankar; Saxena, Pramod R; Villalón, Carlos M

    2003-01-01

    Continuous infusions of 5-hydroxytryptamine (5-HT) inhibit the tachycardiac responses to preganglionic (C7-T1) sympathetic stimulation in pithed rats pretreated with desipramine. The present study identified the pharmacological profile of this inhibitory action of 5-HT. The inhibition induced by intravenous (i.v.) continuous infusions of 5-HT (5.6 μg kg−1 min−1) on sympathetically induced tachycardiac responses remained unaltered after i.v. treatment with saline or the antagonists GR 127935 (5-HT1B/1D), the combination of WAY 100635 (5-HT1A) plus GR 127935, ritanserin (5-HT2), tropisetron (5-HT3/4), LY215840 (5-HT7) or a cocktail of antagonists/inhibitors consisting of yohimbine (α2), prazosin (α1), ritanserin, GR 127935, WAY 100635 and indomethacin (cyclooxygenase), but was abolished by methiothepin (5-HT1/2/6/7 and recombinant 5-ht5A/5B). These drugs, used in doses high enough to block their respective receptors/mechanisms, did not modify the sympathetically induced tachycardiac responses per se. I.v. continuous infusions of the agonists 5-carboxamidotryptamine (5-CT; 5-HT1/7 and recombinant 5-ht5A/5B), CP 93,129 (r5-HT1B), sumatriptan (5-HT1B/1D), PNU-142633 (5-HT1D) and ergotamine (5-HT1B/1D and recombinant 5-ht5A/5B) mimicked the above sympatho-inhibition to 5-HT. In contrast, the agonists indorenate (5-HT1A) and LY344864 (5-ht1F) were inactive. Interestingly, 5-CT-induced cardiac sympatho-inhibition was abolished by methiothepin, the cocktail of antagonists/inhibitors, GR 127935 or the combination of SB224289 (5-HT1B) plus BRL15572 (5-HT1D), but remained unchanged when SB224289 or BRL15572 were given separately. Therefore, 5-HT-induced cardiac sympatho-inhibition, being unrelated to 5-HT2, 5-HT3, 5-HT4, 5-ht6, 5-HT7 receptors, α1/2-adrenoceptor or prostaglandin synthesis, seems to be primarily mediated by (i) 5-HT1 (probably 5-HT1B/1D) receptors and (ii) a novel mechanism antagonized by methiothepin that, most likely, involves putative 5-ht5A/5B

  10. 5-HT(1A) and 5-HT(7) receptors differently modulate AMPA receptor-mediated hippocampal synaptic transmission.

    PubMed

    Costa, L; Trovato, C; Musumeci, S A; Catania, M V; Ciranna, L

    2012-04-01

    We have studied the effects of 5-HT(1A) and 5-HT(7) serotonin receptor activation in hippocampal CA3-CA1 synaptic transmission using patch clamp on mouse brain slices. Application of either 5-HT or 8-OH DPAT, a mixed 5-HT(1A)/5-HT(7) receptor agonist, inhibited AMPA receptor-mediated excitatory post synaptic currents (EPSCs); this effect was mimicked by the 5-HT(1A) receptor agonist 8-OH PIPAT and blocked by the 5-HT(1A) antagonist NAN-190. 8-OH DPAT increased paired-pulse facilitation and reduced the frequency of mEPSCs, indicating a presynaptic reduction of glutamate release probability. In another group of neurons, 8-OH DPAT enhanced EPSC amplitude but did not alter paired-pulse facilitation, suggesting a postsynaptic action; this effect persisted in the presence of NAN-190 and was blocked by the 5-HT(7) receptor antagonist SB-269970. To confirm that EPSC enhancement was mediated by 5-HT(7) receptors, we used the compound LP-44, which is considered a selective 5-HT(7) agonist. However, LP-44 reduced EPSC amplitude in most cells and instead increased EPSC amplitude in a subset of neurons, similarly to 8-OH DPAT. These effects were respectively antagonized by NAN-190 and by SB-269970, indicating that under our experimental condition LP-44 behaved as a mixed agonist. 8-OH DPAT also modulated the current evoked by exogenously applied AMPA, inducing either a reduction or an increase of amplitude in distinct neurons; these effects were respectively blocked by 5-HT(1A) and 5-HT(7) receptor antagonists, indicating that both receptors exert a postsynaptic action. Our results show that 5-HT(1A) receptors inhibit CA3-CA1 synaptic transmission acting both pre- and postsynaptically, whereas 5-HT(7) receptors enhance CA3-CA1 synaptic transmission acting exclusively at a postsynaptic site. We suggest that a selective pharmacological targeting of either subtype may be envisaged in pathological loss of hippocampal-dependent cognitive functions. In this respect, we underline the

  11. Agonist properties of N,N-dimethyltryptamine at serotonin 5-HT2A and 5-HT2C receptors.

    PubMed

    Smith, R L; Canton, H; Barrett, R J; Sanders-Bush, E

    1998-11-01

    Extensive behavioral and biochemical evidence suggests an agonist role at the 5-HT2A receptor, and perhaps the 5-HT2C receptor, in the mechanism of action of hallucinogenic drugs. However the published in vitro pharmacological properties of N,N-dimethyltryptamine (DMT), an hallucinogenic tryptamine analog, are not consistent with this hypothesis. We, therefore, undertook an extensive investigation into the properties of DMT at 5-HT2A and 5-HT2C receptors. In fibroblasts transfected with the 5-HT2A receptor or the 5-HT2C receptor, DMT activated the major intracellular signaling pathway (phosphoinositide hydrolysis) to an extent comparable to that produced by serotonin. Because drug efficacy changes with receptor density and cellular microenvironment, we also examined the properties of DMT in native preparations using a behavioral and biochemical approach. Rats were trained to discriminate an antagonist ketanserin from an agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) in a two-lever choice paradigm. Pharmacological studies showed that responding on the DOI and ketanserin lever reflected agonist and antagonist activity at 5-HT2A receptors, and hence, was a suitable model for evaluating the in vivo functional properties of DMT. Like other 5-HT2A receptor agonists, DMT substituted fully for DOI. Intact choroid plexus was used to evaluate the agonist properties at endogenous 5-HT2C receptors; DMT was a partial agonist at 5-HT2C receptors in this native preparation. Thus, we conclude that DMT behaves as an agonist at both 5-HT2A and 5-HT2A receptors. One difference was evident in that the 5-HT2C, but not the 5-HT2A, receptor showed a profound desensitization to DMT over time. This difference is interesting in light of the recent report that the hallucinogenic activity of DMT does not tolerate in humans and suggests the 5-HT2C receptor plays a less prominent role in the action of DMT.

  12. Bivalent Ligands for the Serotonin 5-HT3 Receptor

    PubMed Central

    2011-01-01

    The serotonin 5-HT3 receptor is a ligand-gated ion channel, which by virtue of its pentameric architecture, can be considered to be an intriguing example of intrinsically multivalent biological receptors. This paper describes a general design approach to the study of multivalency in this multimeric ion channel. Bivalent ligands for 5-HT3 receptor have been designed by linking an arylpiperazine moiety to probes showing different functional features. Both homobivalent and heterobivalent ligands have shown 5-HT3 receptor affinity in the nanomolar range, providing evidence for the viability of our design approach. Moreover, the high affinity shown by homobivalent ligands suggests that bivalency is a promising approach in 5-HT3 receptor modulation and provides the rational basis for applying the concepts of multivalency to the study of 5-HT3 receptor function. PMID:24900351

  13. Molecular dynamics simulation of the structure and dynamics of 5-HT3 serotonin receptor

    NASA Astrophysics Data System (ADS)

    Antonov, M. Yu.; Popinako, A. V.; Prokopiev, G. A.

    2016-10-01

    In this work, we investigated structure, dynamics and ion transportation in transmembrane domain of the 5-HT3 serotonin receptor. High-resolution (0.35 nm) structure of the 5-HT3 receptor in complex with stabilizing nanobodies was determined by protein crystallography in 2014 (Protein data bank (PDB) code 4PIR). Transmembrane domain of the structure was prepared in complex with explicit membrane environment (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC)) and solvent (TIP3P water model). Molecular dynamics protocols for simulation and stabilization of the transmembrane domain of the 5-HT3 receptor model were developed and 60 ns simulation of the structure was conducted in order to explore structural parameters of the system. We estimated the mean force profile for Na+ ions using umbrella sampling method.

  14. 5-HTT and 5-HT(1A) receptor occupancy of the novel substance vortioxetine (Lu AA21004). A PET study in control subjects.

    PubMed

    Stenkrona, Per; Halldin, Christer; Lundberg, Johan

    2013-10-01

    Vortioxetine (Lu AA21004) is a new potential substance for the treatment of anxiety and mood disorders. It has high affinity for the 5-HT transporter (5-HTT) and moderate affinity for the 5-HT1A receptor in vitro. Positron emission tomography (PET) has commonly been used to examine the relation between dose/plasma concentration and occupancy to predict relevant dose intervals in a clinical setting. In this study 11 control subjects were examined with PET and [¹¹C]MADAM at baseline, after a single dose and after 9 days of dosing with Lu AA21004 (2.5, 10 or 60 mg) for quantification of 5-HTT occupancy. Four subjects were examined with PET and [¹¹C]WAY 100635 at baseline, after a single dose and after 9 days of dosing of Lu AA21004 (30 mg) for quantification of 5-HT(1A) occupancy. To allow for quantification of binding in the raphe nuclei, PET data were analyzed using wavelet aided parametric imaging. 5-HTT occupancy ranged from 2 (mean, 2.5 mg day 1) to 97% (60 mg day 9). The apparent affinity of Lu AA21004 binding to 5-HTT (KD(ND)) was calculated to 16.7 nM (R=0.95), and the corresponding oral dose (KD(ND)-dose) to 8.5 mg (R=0.91). No significant occupancy of 5-HT(1A) receptors was found after dosing of 30 mg Lu AA21004. Based on the literature and the present [¹¹C]MADAM binding data, a dose of 20-30 mg Lu AA21004 is suggested to give clinically relevant occupancy of the 5-HTT.

  15. Down-regulation of cerebellar 5-HT(2C) receptors in pilocarpine-induced epilepsy in rats: therapeutic role of Bacopa monnieri extract.

    PubMed

    Krishnakumar, Amee; Abraham, Pretty Mary; Paul, Jes; Paulose, C S

    2009-09-15

    Epilepsy is a syndrome of episodic brain dysfunction characterized by recurrent unpredictable, spontaneous seizures. Cerebellar dysfunction is a recognized complication of temporal lobe epilepsy and it is associated with seizure generation, motor deficits and memory impairment. Serotonin is known to exert a modulatory action on cerebellar function through 5HT(2C) receptors. 5-HT(2C) receptors are novel targets for developing anti-convulsant drugs. In the present study, we investigated the changes in the 5-HT(2C) receptors binding and gene expression in the cerebellum of control, epileptic and Bacopa monnieri treated epileptic rats. There was a significant down regulation of the 5-HT content (p<0.001), 5-HT(2C) gene expression (p<0.001) and 5-HT(2C) receptor binding (p<0.001) with an increased affinity (p<0.001). Carbamazepine and B. monnieri treatments to epileptic rats reversed the down regulated 5-HT content (p<0.01), 5-HT(2C) receptor binding (p<0.001) and gene expression (p<0.01) to near control level. Also, the Rotarod test confirms the motor dysfunction and recovery by B. monnieri treatment. These data suggest the neuroprotective role of B. monnieri through the upregulation of 5-HT(2C) receptor in epileptic rats. This has clinical significance in the management of epilepsy.

  16. Differential expression of 5-HT-related genes in symptomatic pulmonary embolism patients

    PubMed Central

    Jin, Yun; Wang, Lemin; Duan, Qianglin; Gong, Zhu; Yang, Fan; Song, Yanli

    2015-01-01

    Objective: Whole human genome oligo microarrays were employed to systematically investigate the mRNA expression profile of 5-HT synthetase, transporter, receptor, and factors in 5-HT signaling pathway in peripheral blood karyocytes from pulmonary embolism (PE) patients. Methods: A total of 20 PE patients and 20 healthy subjects matched in gender and age were recruited. The human genome microarrays were performed to detect the mRNA expression profile of 5-HT synthetase, transporter, receptor, and factors in 5-HT signal pathway of two groups. The random variance model corrected t-test was used for analysis. Results: Our results showed (1) tryptophan hydroxylase (TPH1)-related gene expression was markedly down-regulated in PE patients (P < 0.01); (2) monoamine oxidases (MAO)-related gene (MAOB) expression was significantly up-regulated in PE patients (P < 0.01); (3) the expression of 17 genes of 7 5-HT receptors showed a down-regulated tendency in PE patients, and significant difference was observed in the expression of HTR1E, HTR3B, HTR4 and HTR5A between them (P < 0.05); (4) the expression of DalDAG-GEF I, Tubby, PKA and EPAC in 5-HT signal pathways was dramatically up-regulated in PE patients (P < 0.05); the expression of SPA1, RIAM, RAPL, Talin, PKC, PLC and Pyk2 was remarkably up-regulated in PE patients (P < 0.05); (5) the expression of integrin genes ITGA2B, ITGB1 and ITGB3 was significantly up-regulated in PE patients (P < 0.05). Conclusion: In PE patients, the expression of TPH1 and HTR4 was down-regulated as a negative feedback; the MAOB expression was up-regulated. Consistent with the expression of 5-HTR1E and 5-HTR4 and the abnormally activated Tubby, the expression of integrins in platelets was activated. PMID:25785024

  17. [On the role of selective silencer Freud-1 in the regulation of the brain 5-HT(1A) receptor gene expression].

    PubMed

    Naumenko, V S; Osipova, D V; Tsybko, A S

    2010-01-01

    Selective 5-HT(1A) receptor silencer (Freud-1) is known to be one of the main factors for transcriptional regulation of brain serotonin 5-HT(1A) receptor. However, there is a lack of data on implication of Freud-1 in the mechanisms underlying genetically determined and experimentally altered 5-HT(1A) receptor system state in vivo. In the present study we have found a difference in the 5-HT(1A) gene expression in the midbrain of AKR and CBA inbred mouse strains. At the same time no distinction in Freud-1 expression was observed. We have revealed 90.3% of homology between mouse and rat 5-HT(1A) receptor DRE-element, whereas there was no difference in DRE-element sequence between AKR and CBA mice. This indicates the absence of differences in Freud-1 binding site in these mouse strains. In the model of 5-HT(1A) receptor desensitization produced by chronic 5-HT(1A) receptor agonist administration, a significant reduction of 5-HT(1A) receptor gene expression together with considerable increase of Freud-1 expression were found. These data allow us to conclude that the selective silencer of 5-HT(1A) receptor, Freud-1, is involved in the compensatory mechanisms that modulate the functional state of brain serotonin system, although it is not the only factor for 5-HT(1A) receptor transcriptional regulation.

  18. 5-HT1A receptor pharmacophores to screen for off-target activity of α1-adrenoceptor antagonists

    NASA Astrophysics Data System (ADS)

    Ngo, Tony; Nicholas, Timothy J.; Chen, Junli; Finch, Angela M.; Griffith, Renate

    2013-04-01

    The α1-adrenoceptors (α1-ARs), in particular the α1A-AR subtype, are current therapeutic targets of choice for the treatment of urogenital conditions, such as benign prostatic hyperplasia (BPH). Due to the similarity between the transmembrane domains of the α1-AR subtypes, and the serotonin receptor subtype 1A (5-HT1A-R), currently used α1-AR subtype-selective drugs to treat BPH display considerable off-target affinity for the 5-HT1A-R, leading to side effects. We describe the construction and validation of pharmacophores for 5-HT1A-R agonists and antagonists. Through the structural diversity of the training sets used in their development, these pharmacophores define the properties of a compound needed to bind to 5-HT1A receptors. Using these and previously published pharmacophores in virtual screening and profiling, we have identified unique chemical compounds (hits) that fit the requirements to bind to our target, the α1A-AR, selectively over the off-target, the 5-HT1A-R. Selected hits have been obtained and their affinities for α1A-AR, α1B-AR and 5-HT1A-R determined in radioligand binding assays, using membrane preparations which contain human receptors expressed individually. Three of the tested hits demonstrate statistically significant selectivity for α1A-AR over 5-HT1A-R. All seven tested hits bind to α1A-AR, with two compounds displaying K i values below 1 μM, and a further two K i values of around 10 μM. The insights and knowledge gained through the development of the new 5-HT1A-R pharmacophores will greatly aid in the design and synthesis of derivatives of our lead compound, and allow the generation of more efficacious and selective ligands.

  19. Toward Biophysical Probes for the 5-HT3 Receptor: Structure−Activity Relationship Study of Granisetron Derivatives

    PubMed Central

    2010-01-01

    This report describes the synthesis and biological characterization of novel granisetron derivatives that are antagonists of the human serotonin (5-HT3A) receptor. Some of these substituted granisetron derivatives showed low nanomolar binding affinity and allowed the identification of positions on the granisetron core that might be used as attachment points for biophysical tags. A BODIPY fluorophore was appended to one such position and specifically bound to 5-HT3A receptors in mammalian cells. PMID:20146481

  20. Towards metabolically stable 5-HT7 receptor ligands: a study on 1-arylpiperazine derivatives and related isosters.

    PubMed

    Lacivita, Enza; De Giorgio, Paola; Patarnello, Daniela; Niso, Mauro; Colabufo, Nicola A; Berardi, Francesco; Perrone, Roberto; Satala, Grzegorz; Duszynska, Beata; Bojarski, Andrzej J; Leopoldo, Marcello

    2013-10-01

    Serotonin 7 (5-hydroxytryptamine7 or 5-HT7) is the most recently identified serotonin receptor. It is involved in mood disorders and is studied as a target for antidepressants. Here, we report on the structural manipulation of the 5-HT7 receptor ligand 4-[2-(3-methoxyphenyl)ethyl]-1-(2-methoxyphenyl)piperazine (1a) aimed at obtaining 5-HT7 receptor ligands endowed with good in vitro metabolic stability. A set of N-[3-methoxyphenyl)ethyl-substituted] 1-arylpiperazine, 4-arylpiperidine and 1-aryl-4-aminopiperidine was synthesized and tested in radioligand binding assays at human cloned 5-HT7 and 5-HT1A receptors. In vitro metabolic stability of the target compounds was assessed after incubation with rat hepatic S9 microsomal fraction. Among the new compounds, 1-(2-biphenyl)-4-[2-(3-methoxyphenyl)ethyl]piperazine (1d) and 4-(2-biphenyl)-1-[2-(3-methoxyphenyl)ethyl]piperidine (2d) showed a good compromise between affinity at 5-HT7 receptor (K i = 7.5 nM and 13 nM, respectively) and in vitro metabolic stability (26 and 65 % recovery of parent compound, respectively) but were poorly selective over 5-HT1A receptor.

  1. New N- and O-arylpiperazinylalkyl pyrimidines and 2-methylquinazolines derivatives as 5-HT7 and 5-HT1A receptor ligands: Synthesis, structure-activity relationships, and molecular modeling studies.

    PubMed

    Intagliata, Sebastiano; Modica, Maria N; Pittalà, Valeria; Salerno, Loredana; Siracusa, Maria A; Cagnotto, Alfredo; Salmona, Mario; Kurczab, Rafał; Romeo, Giuseppe

    2017-02-01

    Based on our earlier studies of structure activity relationships on 4-substituted piperazine derivatives, in this work we synthesized a novel set of long-chain arylpiperazines with the purpose of elucidating if some structural modifications in the terminal fragment could affect the binding affinity for the 5-HT7 and 5-HT1A receptors. In this new series, the quinazolinone system of the previous derivatives was replaced by a 6-phenylpyrimidine or a 2-methylquinazoline, which were used as versatile building blocks for the preparation of new compounds. A 4-arylpiperazine moiety through a five methylene chain was anchored at the nitrogen or oxygen atom of the heterocyclic scaffolds. The substituents borne by the piperazine nucleus were phenyl, phenylmethyl, 3- or 4-chlorophenyl, and 2-ethoxyphenyl. Binding tests, performed on human cloned 5-HT7 and 5-HT1A receptors, showed that, among the newly synthesized derivatives, 4-[5-[4-(2-ethoxyphenyl)-1-piperazinyl]pentoxy]-6-phenyl-pyrimidine (13) and 3-[5-[4-(2-ethoxyphenyl)-1-piperazinyl]pentyl]-2-methyl-4(3H)-quinazolinone (20) displayed the best affinity values, Ki=23.5 and 8.42nM for 5-HT7 and 6.96 and 2.99nM for 5-HT1A receptors, respectively. Moreover, the functional properties for both compounds were further evaluated using the cAMP assay. Finally, a molecular modeling study has been performed for 5-HT7 and 5-HT1A receptor homology models to investigate the binding mode of N- and O-alkylated pyrimidinones/pyrimidines 4-13, 2-methylquinazolinones/quinazolines 17-22, and previously reported 2- and 3-substituted quinazolinones 23-30.

  2. Subunit rotation models activation of serotonin 5-HT3AB receptors by agonists

    NASA Astrophysics Data System (ADS)

    Maksay, Gábor; Simonyi, Miklós; Bikádi, Zsolt

    2004-10-01

    The N-terminal extracellular regions of heterooligomeric 3AB-type human 5-hydroxytryptamine receptors (5-HT 3ABR) were modelled based on the crystal structure of snail acetylcholine binding protein AChBP. Stepwise rotation of subunit A by 5° was performed between -10° and 15° to mimic agonist binding and receptor activation. Anticlockwise rotation reduced the size of the binding cavity in interface AB and reorganised the network of hydrogen bonds along the interface. AB subunit dimers with different rotations were applied for docking of ligands with different efficacies: 5-HT, m-chlorophenylbiguanide, SR 57227, quinolinyl piperazine and lerisetron derivatives. All ligands were docked into the dimer with -10° rotation representing ligand-free, open binding cavities similarly, without pharmacological discrimination. Their ammonium ions were in hydrogen bonding distance to the backbone carbonyl of W183. Anticlockwise rotation and contraction of the binding cavity led to distinctive docking interactions of agonists with E129 and cation-π interactions of their ammonium ions. Side chains of several further amino acids participating in docking (Y143, Y153, Y234 and E236) are in agreement with the effects of point mutations in the binding loops. Our model postulates that 5-HT binds to W183 in a hydrophobic cleft as well as to E236 in a hydrophilic vestibule. Then it elicits anticlockwise rotation to draw in loop C via π-cation-π interactions of␣its ammonium ion with W183 and Y234. Finally, closure of the binding cavity might end in rebinding of 5-HT to E129 in the hydrophilic vestibule.

  3. Role of Serotonin via 5-HT2B Receptors in the Reinforcing Effects of MDMA in Mice

    PubMed Central

    Doly, Stéphane; Bertran-Gonzalez, Jesus; Callebert, Jacques; Bruneau, Alexandra; Banas, Sophie Marie; Belmer, Arnauld; Boutourlinsky, Katia; Hervé, Denis; Launay, Jean-Marie; Maroteaux, Luc

    2009-01-01

    The amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) reverses dopamine and serotonin transporters to produce efflux of dopamine and serotonin, respectively, in regions of the brain that have been implicated in reward. However, the role of serotonin/dopamine interactions in the behavioral effects of MDMA remains unclear. We previously showed that MDMA-induced locomotion, serotonin and dopamine release are 5-HT2B receptor-dependent. The aim of the present study was to determine the contribution of serotonin and 5-HT2B receptors to the reinforcing properties of MDMA. We show here that 5-HT2B−/− mice do not exhibit behavioral sensitization or conditioned place preference following MDMA (10 mg/kg) injections. In addition, MDMA-induced reinstatement of conditioned place preference after extinction and locomotor sensitization development are each abolished by a 5-HT2B receptor antagonist (RS127445) in wild type mice. Accordingly, MDMA-induced dopamine D1 receptor-dependent phosphorylation of extracellular regulated kinase in nucleus accumbens is abolished in mice lacking functional 5-HT2B receptors. Nevertheless, high doses (30 mg/kg) of MDMA induce dopamine-dependent but serotonin and 5-HT2B receptor-independent behavioral effects. These results underpin the importance of 5-HT2B receptors in the reinforcing properties of MDMA and illustrate the importance of dose-dependent effects of MDMA on serotonin/dopamine interactions. PMID:19956756

  4. The effects of chronic ethanol self-administration on hippocampal 5-HT1A receptors in monkeys

    PubMed Central

    Burnett, Elizabeth J.; Grant, Kathleen A.; Davenport, April T.; Hemby, Scott E.; Friedman, David P.

    2014-01-01

    BACKGROUND Chronic alcohol consumption reduces brain serotonin and alters the synaptic mechanisms involved in memory formation. Hippocampal 5-HT1A receptors modulate these mechanisms, but the neuroadaptive response of 5HT1A receptors to chronic alcohol self-administration is not well understood. METHODS Hippocampal tissue from monkeys that voluntarily self-administered ethanol for 12 months (n=9) and accompanying controls (n=8) were prepared for in vitro receptor autoradiography and laser capture microdissection. The 5-HT1A receptor antagonist, [3H]MPPF, and the agonist, [3H]8-OH-DPAT, were used to measure total and G-protein coupled 5-HT1A receptors respectively. The expression of the genes encoding the 5-HT1A receptor and its trafficking protein Yif1B was measured in microdissected dentate gyrus (DG) granule cells and CA1 pyramidal neurons. RESULTS An increase in G-protein coupled, but not total, receptors was observed in the posterior pyramidal cell layer of CA1 in ethanol drinkers compared to controls. Chronic ethanol self-administration was also associated with an up-regulation of total and G-protein coupled 5-HT1A receptors in the posterior DG polymorphic layer. Changes in receptor binding were not associated with concomitant changes in 5-HT1A receptor mRNA expression. Chronic ethanol self-administration was associated with a significant increase in Yif1B gene expression in posterior CA1 pyramidal neurons. CONCLUSIONS Chronic, ethanol self-administration up-regulates hippocampal 5-HT1A receptor density in a region-specific manner that does not appear to be due to alterations at the level of transcription but instead may be due to increased receptor trafficking. Further exploration of the mechanisms mediating chronic ethanol-induced 5-HT1A receptor up-regulation and how hippocampal neurotransmission is altered is warranted. PMID:24467872

  5. Studies of the biogenic amine transporters. IV. Demonstration of a multiplicity of binding sites in rat caudate membranes for the cocaine analog [125I]RTI-55.

    PubMed

    Rothman, R B; Cadet, J L; Akunne, H C; Silverthorn, M L; Baumann, M H; Carroll, F I; Rice, K C; de Costa, B R; Partilla, J S; Wang, J B

    1994-07-01

    The drug 3 beta-[4'-iodophenyl]tropan-2 beta-carboxylic acid methyl ester (RTI-55) is a cocaine congener with high affinity for the dopamine transporter (Kd < 1 nM). The present study characterized [125I]RTI-55 binding to membranes prepared from rat, monkey and human caudates and COS cells transiently expressing the cloned rat dopamine (DA) transporter. Using the method of binding surface analysis, two binding sites were resolved in rat caudate: a high-capacity binding site (site 1, Bmax = 11,900 fmol/mg of protein) and a low-capacity site (site 2, Bmax = 846 fmol/mg of protein). The Kd (or Ki) values of selected drugs at the two sites were as follows: (Ki for high-capacity site and Ki for low-capacity site, respectively): RTI-55 (0.76 and 0.21 nM), 1-[2-diphenyl-methoxy)ethyl]-4-(3-phenylpropyl)piperazine (0.79 and 358 nM), mazindol (37.6 and 631 nM), 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane (45.0 and 540 nM) and cocaine (341 and 129 nM). Nisoxetine, a selective noradrenergic uptake blocker, had low affinity for both sites. Serotonergic uptake blockers had a high degree of selectivity and high affinity for the low-capacity binding site (Ki of citalopram = 0.38 nM; Ki of paroxetine = 0.033 nM). The i.c.v. administration of 5,7-dihydroxytryptamine to rats pretreated with nomifensine (to protect dopaminergic and noradrenergic nerve terminals) selectively decreased the Bmax of site 2, strongly supporting the idea that site 2 is a binding site on the serotonin (5-HT) transporter. This serotonergic lesion also increased the affinity of [125I]RTI-55 for the DA transporter by 10-fold. The ligand selectivity of the caudate 5-HT transporter was different from the [I125]RTI-55 binding site on the 5-HT transporter present in membranes prepared from whole rat brain minus caudate. The [125I]RTI-55 binding to the DA transporter was further resolved into two components, termed sites 1a and 1b, by using human and monkey (Macaca mulatta) caudate membranes but not the

  6. Shuyu Capsules Relieve Premenstrual Syndrome Depression by Reducing 5-HT3AR and 5-HT3BR Expression in the Rat Brain

    PubMed Central

    Li, Fang; Feng, Jizhen; Gao, Dongmei; Wang, Jieqiong; Song, Chunhong; Wei, Sheng

    2016-01-01

    The effects of the Shuyu capsule on 5-HT3AR and 5-HT3BR expression in a rat model of premenstrual syndrome (PMS) depression and on 5-HT3AR and 5-HT3BR expression and hippocampal neuron 5-HT3 channel current were investigated, to elucidate its mechanism of action against PMS depression. PMS depression model rats were divided into depression and Shuyu- and fluoxetine-treated groups, which were compared to control rats for frontal lobe and hippocampal 5-HT3AR and 5-HT3BR expression and behavior. The depressed model rats displayed symptoms of depression, which were reduced in treated and normal control rats. Frontal lobe and hippocampal 5-HT3AR and 5-HT3BR levels were significantly higher in the model versus the control group and were significantly lower in the Shuyu group. As compared to control rats, the 5-HT3R channel current in the model group was significantly higher; the 5-HT3R channel current in hippocampal neurons treated with serum from Shuyu group rats was significantly lower than that in those treated with model group serum. Thus, PMS depression may be related to 5-HT3AR and 5-HT3BR expression and increased 5-HT3 channel current. Shuyu capsules rectified abnormal 5-HT3AR and 5-HT3BR expression and 5-HT3 channel current changes in a rat model; this finding may provide insight into treating PMS depression. PMID:27725889

  7. 2-Amino-6-chloro-3,4-dihydroquinazoline: A novel 5-HT3 receptor antagonist with antidepressant character.

    PubMed

    Dukat, Małgorzata; Alix, Katie; Worsham, Jessica; Khatri, Shailesh; Schulte, Marvin K

    2013-11-01

    2-Amino-6-chloro-3,4-dihydroquinazoline HCl (A6CDQ, 4) binds at 5-HT3 serotonin receptors and displays antidepressant-like action in the mouse tail suspension test (TST). Empirically, 4 was demonstrated to be a 5-HT3 receptor antagonist (two-electrode voltage clamp recordings using frog oocytes; IC50=0.26μM), and one that should readily penetrate the blood-brain barrier (logP=1.86). 5-HT3 receptor antagonists represent a potential approach to the development of new antidepressants, and 4 is an example of a structurally novel 5-HT3 receptor antagonist that is active in a preclinical antidepressant model (i.e., the mouse TST).

  8. Upregulation of 5-HT2C receptors in hippocampus of pilocarpine-induced epileptic rats: antagonism by Bacopa monnieri.

    PubMed

    Krishnakumar, Amee; Nandhu, M S; Paulose, C S

    2009-10-01

    Emotional disturbances, depressive mood, anxiety, aggressive behavior, and memory impairment are the common psychiatric features associated with temporal lobe epilepsy (TLE). The present study was carried out to investigate the role of Bacopa monnieri extract in hippocampus of pilocarpine-induced temporal lobe epileptic rats through the 5-HT(2C) receptor in relation to depression. Our results showed upregulation of 5-HT(2C) receptors with a decreased affinity in hippocampus of pilocarpine-induced epileptic rats. Also, there was an increase in 5-HT(2C) gene expression and inositol triphosphate content in epileptic hippocampus. Carbamazepine and B. monnieri treatments reversed the alterations in 5-HT(2C) receptor binding, gene expression, and inositol triphosphate content in treated epileptic rats as compared to untreated epileptic rats. The forced swim test confirmed the depressive behavior pattern during epilepsy that was nearly completely reversed by B. monnieri treatment.

  9. Spinal 5-HT1A, not the 5-HT1B or 5-HT3 receptors, mediates descending serotonergic inhibition for late-phase mechanical allodynia of carrageenan-induced peripheral inflammation.

    PubMed

    Kim, Joung Min; Jeong, Seong Wook; Yang, Jihoon; Lee, Seong Heon; Kim, Woon Mo; Jeong, Seongtae; Bae, Hong Beom; Yoon, Myung Ha; Choi, Jeong Il

    2015-07-23

    Previous electrophysiological studies demonstrated a limited role of 5-hydroxytryptamine 3 receptor (5-HT3R), but facilitatory role of 5-HT1AR and 5-HT1BR in spinal nociceptive processing of carrageenan-induced inflammatory pain. The release of spinal 5-HT was shown to peak in early-phase and return to baseline in late-phase of carrageenan inflammation. We examined the role of the descending serotonergic projections involving 5-HT1AR, 5-HT1BR, and 5-HT3R in mechanical allodynia of early- (first 4h) and late-phase (24h after) carrageenan-induced inflammation. Intrathecal administration of 5-HT produced a significant anti-allodynic effect in late-phase, but not in early-phase. Similarly, intrathecal 5-HT1AR agonist (8-OH-DPAT) attenuated the intensity of late-phase allodynia in a dose dependent fashion which was antagonized by 5-HT1AR antagonist (WAY-100635), but produced no effect on the early-phase allodynia. However, other agonists or antagonists of 5-HT1BR (CP-93129, SB-224289) and 5-HT3R (m-CPBG, ondansetron) did not produce any anti- or pro-allodynic effect in both early- and late- phase allodynia. These results suggest that spinal 5-HT1A, but not 5-HT1B or 5-HT3 receptors mediate descending serotonergic inhibition on nociceptive processing of late-phase mechanical allodynia in carrageenan-induced inflammation.

  10. Pharmacological profile of DA-6886, a novel 5-HT4 receptor agonist to accelerate colonic motor activity in mice.

    PubMed

    Lee, Min Jung; Cho, Kang Hun; Park, Hyun Min; Sung, Hyun Jung; Choi, Sunghak; Im, Weonbin

    2014-07-15

    DA-6886, the gastrointestinal prokinetic benzamide derivative is a novel 5-HT4 receptor agonist being developed for the treatment of constipation-predominant irritable bowel syndrome (IBS-C). The purpose of this study was to characterize in vitro and in vivo pharmacological profile of DA-6886. We used various receptor binding assay, cAMP accumulation assay, organ bath experiment and colonic transit assay in normal and chemically constipated mice. DA-6886 exhibited high affinity and selectivity to human 5-HT4 receptor splice variants, with mean pKi of 7.1, 7.5, 7.9 for the human 5-HT4a, 5-HT4b and 5-HT4d, respectively. By contrast, DA-6886 did not show significant affinity for several receptors including dopamine D2 receptor, other 5-HT receptors except for 5-HT2B receptor (pKi value of 6.2). The affinity for 5-HT4 receptor was translated into functional agonist activity in Cos-7 cells expressing 5-HT4 receptor splice variants. Furthermore, DA-6886 induced relaxation of the rat oesophagus preparation (pEC50 value of 7.4) in a 5-HT4 receptor antagonist-sensitive manner. The evaluation of DA-6886 in CHO cells expressing hERG channels revealed that it inhibited hERG channel current with an pIC50 value of 4.3, indicating that the compound was 1000-fold more selective for the 5-HT4 receptor over hERG channels. In the normal ICR mice, oral administration of DA-6886 (0.4 and 2mg/kg) resulted in marked stimulation of colonic transit. Furthermore, in the loperamide-induced constipation mouse model, 2mg/kg of DA-6886 significantly improved the delay of colonic transit, similar to 10mg/kg of tegaserod. Taken together, DA-6886 is a highly potent and selective 5-HT4 receptor agonist to accelerate colonic transit in mice, which might be therapeutic agent having a favorable safety profile in the treatment of gastrointestinal motor disorders such as IBS-C and chronic constipation.

  11. Tianeptine: 5-HT uptake sites and 5-HT(1-7) receptors modulate memory formation in an autoshaping Pavlovian/instrumental task.

    PubMed

    Meneses, Alfredo

    2002-05-01

    Recent studies using invertebrate and mammal species have revealed that, endogenous serotonin (5-hydroxytryptamine, 5-HT) modulates cognitive processes, particularly learning and memory, though, at present, it is unclear the manner, where, and how long 5-HT systems are involved. Hence in this work, an attempt was made to study the effects of 5-HT endogenous on memory formation, using a 5-HT uptake facilitator (tianeptine) and, selective 5-HT(1-7) receptor antagonists to determine whether 5-HT uptake sites and which 5-HT receptors are involved, respectively. Results showed that post-training tianeptine injection enhanced memory consolidation in an autoshaping Pavlovian/instrumental learning task, which has been useful to detect changes on memory formation elicited by drugs or aging. On interaction experiments, ketanserin (5-HT(1D/2A/2C) antagonist) slightly enhanced tianeptine effects, while WAY 100635 (5-HT(1A) antagonist), SB-224289 (5-HT(1B) inverse agonist), SB-200646 (5-HT(2B/2C) antagonist), ondansetron (5-HT(3) antagonist), GR 127487 (5-HT(4) antagonist), Ro 04-6790 (5-HT(6) antagonist), DR 4004 (5-HT(7) antagonist), or fluoxetine (an inhibitor of 5-HT reuptake) blocked the facilitatory tianeptine effect. Notably, together tianeptine and Ro 04-6790 impaired learning consolidation. Moreover, 5-HT depletion completely reversed the tianeptine effect. Tianeptine also normalized an impaired memory elicited by scopolamine (an antimuscarinic) or dizocilpine (non-competitive glutamatergic antagonist), while partially reversed that induced by TFMPP (5-HT(1B/1D/2A-2C/7) agonist/antagonist). Finally, tianeptine-fluoxetine coadministration had no effect on learning consolidation; nevertheless, administration of an acetylcholinesterase inhibitor, phenserine, potentiated subeffective tianeptine or fluoxetine doses. Collectively, these data confirmed that endogenously 5-HT modulates, via uptake sites and 5-HT(1-7) receptors, memory consolidation, and are consistent with the

  12. Verbal memory and 5-HT1A receptors in healthy volunteers--A PET study with [carbonyl-(11)C]WAY-100635.

    PubMed

    Penttilä, Jani; Hirvonen, Jussi; Tuominen, Lauri; Lumme, Ville; Ilonen, Tuula; Någren, Kjell; Hietala, Jarmo

    2016-03-01

    The serotonin 5-HT1A receptor is a putative drug development target in disorders with cognitive and in particular memory deficits. However, previous human positron emission tomography (PET) studies on 5-HT1A receptor binding and memory functions have yielded discrepant results. We explored the association between verbal memory and 5-HT1A receptor binding in 24 healthy subjects (14 male, 10 female, aged 18-41 years). The cognitive tests included the Wechsler Memory Scale-Revised (WMS-R), Wechsler Adult Intelligence Scale-Revised (WAIS-R) and Wisconsin Card Sorting Test (WCST). 5-HT1A receptor binding was measured with PET and the radioligand [carbonyl-(11)C]WAY-100635, which was quantified with the gold standard method based on kinetic modeling using arterial blood samples. We found that global 5-HT1A receptor binding was positively correlated with measures of verbal memory, such that subjects who had higher receptor binding tended to have better verbal memory than subjects who had lower receptor binding. Regional analyses suggested significant correlations in multiple neocortical brain regions and the raphe nuclei. We did not find significant correlations between 5-HT1A receptor binding and executive functions as measured with WCST. We conclude that neocortical as well as raphe 5-HT1A receptors are involved in verbal memory function in man.

  13. Platelet serotonin uptake and paroxetine binding among allelic genotypes of the serotonin transporter in alcoholics.

    PubMed

    Javors, Martin A; Seneviratne, Chamindi; Roache, John D; Ait-Daoud, Nassima; Bergeson, Susan E; Walss-Bass, M Consuelo; Akhtar, Fatema Z; Johnson, Bankole A

    2005-01-01

    Expression rates of long (L) and short (S) alleles of the serotonin (5-HT) transporter (5-HTT) gene have been shown to differ under various circumstances. We compared 5-HTT uptake (function) level and paroxetine binding (density) in platelets of alcoholics as indices of 5-HTT expression rate among LL, LS, and SS genotypes. Concentration curves of [3H]5-HT and [3H]paroxetine were used to quantify the equilibrium constant (Km) and maximum 5-HT uptake rate (Vmax) for 5-HTT uptake into intact platelets and the dissociation constant (Kd) and maximum specific binding density (Bmax) for paroxetine binding to platelet membranes, respectively. Genotypes were determined using electrophoresis with fluorescent markers. Vmax for 5-HTT uptake did not correlate with Bmax for paroxetine binding (r=-0.095, P=0.415). Means of Vmax and Bmax did not differ in a statistically significant manner among LL, LS, and SS genotypes in these alcoholic subjects. However, Vmax for LL and SS appeared to have a bimodal distribution, so the percentage of subjects with Vmax <200 fmol/min-10(7) platelets was statistically significantly higher in LL than in SS (51.5% vs. 22.7%, respectively), with an odds ratio of 3.6 (P<0.05). The percentage of Vmax <200 fmol/min-10(7) platelets for LS was 39.3% (not significant vs. LL or SS). Previous studies of healthy human controls have shown that 5-HTT density in raphe nuclei and 5-HTT uptake in platelets are higher in the LL genotype than in S carriers. Our findings in currently drinking alcoholics support the hypothesis that those with the LL genotype of the 5'-HTTLPR region of the 5-HTT gene have reduced 5-HTT function.

  14. Concentration-Dependent Dual Mode of Zn Action at Serotonin 5-HT1A Receptors: In Vitro and In Vivo Studies.

    PubMed

    Satała, Grzegorz; Duszyńska, Beata; Stachowicz, Katarzyna; Rafalo, Anna; Pochwat, Bartlomiej; Luckhart, Christine; Albert, Paul R; Daigle, Mireille; Tanaka, Kenji F; Hen, René; Lenda, Tomasz; Nowak, Gabriel; Bojarski, Andrzej J; Szewczyk, Bernadeta

    2016-12-01

    Recent data has indicated that Zn can modulate serotonergic function through the 5-HT1A receptor (5-HT1AR); however, the exact mechanisms are unknown. In the present studies, radioligand binding assays and behavioural approaches were used to characterize the pharmacological profile of Zn at 5-HT1ARs in more detail. The influence of Zn on agonist binding to 5-HT1ARs stably expressed in HEK293 cells was investigated by in vitro radioligand binding methods using the agonist [(3)H]-8-OH-DPAT. The in vivo effects of Zn were compared with those of 8-OH-DPAT in hypothermia, lower lip retraction (LLR), 5-HT behavioural syndrome and the forced swim (FST) tests. In the in vitro studies, biphasic effects, which involved allosteric potentiation of agonist binding at sub-micromolar Zn concentrations and inhibition at sub-millimolar Zn concentrations, were found. The in vivo studies showed that Zn did not induce LLR or elements of 5-HT behavioural syndrome but blocked such effects induced by 8-OH-DPAT. Zn decreased body temperature in rats and mice; however, Zn failed to induce hypothermia in the 5-HT1A autoreceptor knockout mice. In the FST, Zn potentiated the effect of 8-OH-DPAT. However, in the FST performed with the 5-HT1A autoreceptor knockout mice, the anti-immobility effect of Zn was partially blocked. Both the binding and behavioural studies suggest a concentration-dependent dual mechanism of Zn action at 5-HT1ARs, with potentiation at low dose and inhibition at high dose. Moreover, the in vivo studies indicate that Zn can modulate both presynaptic and postsynaptic 5-HT1ARs; however, Zn's effects at presynaptic receptors seem to be more potent.

  15. Extended characterisation of the serotonin 2A (5-HT2A) receptor-selective PET radiotracer 11C-MDL100907 in humans: quantitative analysis, test-retest reproducibility, and vulnerability to endogenous 5-HT tone

    PubMed Central

    Talbot, Peter S.; Slifstein, Mark; Hwang, Dah-Ren; Huang, Yiyun; Scher, Erica; Abi-Dargham, Anissa; Laruelle, Marc

    2011-01-01

    Introduction scanning properties and analytic methodology of the 5-HT2A receptor-selective positron emission tomography (PET) tracer 11C-MDL100907 have been partially characterised in previous reports. We present an extended characterisation in healthy human subjects. Methods 64 11C-MDL100907 PET scans with metabolite-corrected arterial input function were performed in 39 healthy adults (18–55 yr). 12 subjects were scanned twice (duration 150 min) to provide data on plasma analysis, model order estimation, and stability and test-retest characteristics of outcome measures. All other scans were 90 min duration. 3 subjects completed scanning at baseline and following 5-HT2A receptor antagonist medication (risperidone or ciproheptadine) to provide definitive data on the suitability of the cerebellum as reference region. 10 subjects were scanned under reduced 5-HT and control conditions using rapid tryptophan depletion to investigate vulnerability to competition with endogenous 5-HT. 13 subjects were scanned as controls in clinical protocols. Pooled data were used to analyze the relationship between tracer injected mass and receptor occupancy, and age-related decline in 5-HT2A receptors. Results optimum analytic method was a 2-tissue compartment model with arterial input function. However, basis function implementation of SRTM may be suitable for measuring between-group differences non-invasively and warrants further investigation. Scan duration of 90 minutes achieved stable outcome measures in all cortical regions except orbitofrontal which required 120 minutes. Binding potential (BPP and BPND) test-retest variability was very good (7–11%) in neocortical regions other than orbitofrontal, and moderately good (14–20%) in orbitofrontal cortex and medial temporal lobe. Saturation occupancy of 5-HT2A receptors by risperidone validates the use of the cerebellum as a region devoid of specific binding for the purposes of PET. We advocate a mass limit of 4.6 µg to remain

  16. Antidepressant- and Anxiolytic-Like Effects of New Dual 5-HT1A and 5-HT7 Antagonists in Animal Models

    PubMed Central

    Pytka, Karolina; Partyka, Anna; Jastrzębska-Więsek, Magdalena; Siwek, Agata; Głuch-Lutwin, Monika; Mordyl, Barbara; Kazek, Grzegorz; Rapacz, Anna; Olczyk, Adrian; Gałuszka, Adam; Błachuta, Marian; Waszkielewicz, Anna; Marona, Henryk; Sapa, Jacek; Filipek, Barbara; Wesołowska, Anna

    2015-01-01

    The aim of this study was to further characterize pharmacological properties of two phenylpiperazine derivatives: 1-{2-[2-(2,6-dimethlphenoxy)ethoxy]ethyl}-4-(2-methoxyphenyl)piperazynine hydrochloride (HBK-14) and 2-[2-(2-chloro-6-methylphenoxy)ethoxy]ethyl-4-(2- methoxyphenyl)piperazynine dihydrochloride (HBK-15) in radioligand binding and functional in vitro assays as well as in vivo models. Antidepressant-like properties were investigated in the forced swim test (FST) in mice and rats. Anxiolytic-like activity was evaluated in the four-plate test in mice and elevated plus maze test (EPM) in rats. Imipramine and escitalopram were used as reference drugs in the FST, and diazepam was used as a standard anxiolytic drug in animal models of anxiety. Our results indicate that HBK-14 and HBK-15 possess high or moderate affinity for serotonergic 5-HT2, adrenergic α1, and dopaminergic D2 receptors as well as being full 5-HT1A and 5-HT7 receptor antagonists. We also present their potent antidepressant-like activity (HBK-14—FST mice: 2.5 and 5 mg/kg; FST rats: 5 mg/kg) and (HBK-15—FST mice: 1.25, 2.5 and 5 mg/kg; FST rats: 1.25 and 2.5 mg/kg). We show that HBK-14 (four-plate test: 2.5 and 5 mg/kg; EPM: 2.5 mg/kg) and HBK-15 (four-plate test: 2.5 and 5 mg/kg; EPM: 5 mg/kg) possess anxiolytic-like properties. Among the two, HBK-15 has stronger antidepressant-like properties, and HBK-14 displays greater anxiolytic-like activity. Lastly, we demonstrate the involvement of serotonergic system, particularly 5-HT1A receptor, in the antidepressant- and anxiolytic-like actions of investigated compounds. PMID:26554929

  17. 5-HT1B receptor-mediated contractions in human temporal artery: evidence from selective antagonists and 5-HT receptor mRNA expression

    PubMed Central

    Verheggen, R; Hundeshagen, A G; Brown, A M; Schindler, M; Kaumann, A J

    1998-01-01

    In the human temporal artery both 5-HT1-like and 5-HT2A receptors mediate the contractile effects of 5-hydroxytryptamine (5-HT) and we have suggested that the 5-HT1-like receptors resemble more closely recombinant 5-HT1B than 5-HT1D receptors. To investigate further which subtype is involved, we investigated the blockade of 5-HT-induced contractions by the 5-HT1B-selective antagonist SB-224289 (2,3,6,7-tetrahydro-1′-methyl-5-{2-methyl-4′[(5-methyl-1,2,4-oxadiazole-3-yl) biphenyl-4-yl] carbonyl} furo[2,3-f]indole-3-spiro-4′-piperidine oxalate) and the 5-HT1D-selective antagonist BRL-15572 (1-phenyl-3[4-3-chlorophenyl piperazin-1-yl] phenylpropan-2-ol). We also used RT-PCR to search for the mRNA of 5-HT1B, 5-HT1D and other 5-HT receptors.The contractile effects of 5-HT in temporal artery rings were partially antagonized by SB-224289 (20, 200 nM) (apparent KB=1 nM) and ketanserin (1 μM) but not by BRL-15572 (500 nM).Sumatriptan evoked contractions (EC50, 170 nM) that were resistant to blockade by BRL-15572 (500 nM) but antagonized by SB-224289 (20, 200 nM).The potency of 5-HT (EC50) was estimated to be 94 nM for the ketanserin-sensitive receptor and 34 nM for the SB-224289-sensitive receptor. The fraction of maximal 5-HT response mediated through SB-224289-sensitive receptors was 0.20–0.67, the remainder being mediated through ketanserin-sensitive receptors.We detected arterial receptor mRNA for the following receptors (incidence): 5-HT1B (8/8), 5-HT1D (2/8), 5-HT1F (0/4), 5-HT2A (0/8), 5-HT2B (0/8), 5-HT2C (0/8), 5-HT4 (4/8) and 5-HT7 (4/8).We conclude that the ketanserin-resistant fraction of the 5-HT effects and the effects of sumatriptan are mediated by 5-HT1B receptors. The lack of antagonism by BRL-15572 rules out 5-HT1D receptors as mediators of the contractile effects of 5-HT and sumatriptan. PMID:9723944

  18. MDMA stimulus generalization to the 5-HT(1A) serotonin agonist 8-hydroxy-2- (di-n-propylamino)tetralin.

    PubMed

    Glennon, R A; Young, R

    2000-07-01

    The abused substance N-methyl-1-(3, 4-methylenedioxyphenyl)-2-aminopropane, or MDMA, serves as a training drug in animals. Because the 5-HT(1A) receptor antagonist NAN-190 has been shown to partially antagonize the MDMA stimulus, and because NAN-190 binds at several different types of receptors, in the present study we examined other agents (e.g., adrenergic, dopaminergic, sigma) in tests of stimulus generalization and stimulus antagonism to determine their influence on the MDMA stimulus. Each of these agents (i.e., clenbuterol, S(-)propranolol, R(+)SCH-23390, amantadine, NANM) was without effect on MDMA-appropriate responding. The finding that NAN-190 behaves as a 5-HT(1A) partial agonist in some studies prompted examination of the 5-HT(1A) receptor agonist 8-OH DPAT and its optical isomers. MDMA-stimulus generalization occurred to racemic 8-OH DPAT (ED(50) = 0.3 mg/kg), R(+)8-OH DPAT (ED(50) = 0.2 mg/kg), and to the 5-HT(1A) receptor partial agonist S(-)8-OH DPAT (ED(50) = 0.4 mg/kg). The results suggest that the MDMA stimulus might possess a 5-HT(1A) component of action. Furthermore, because 8-OH DPAT is known to enhance the stimulus effects of hallucinogens as discriminative stimuli, and because MDMA reportedly enhances the effects of hallucinogenic agents in humans ("flipping," "candy flipping"), this latter MDMA-induced phenomenon might involve a 5-HT(1A) mechanism.

  19. S100B interacts with the serotonin 5-HT7 receptor to regulate a depressive-like behavior.

    PubMed

    Stroth, Nikolas; Svenningsson, Per

    2015-12-01

    The serotonin 5-HT7 receptor (5-HT7) is an emerging target for psychiatric pharmacotherapy. Recent observations in rodent models and humans suggest that its blockade mediates antidepressant efficacy. In the present study, we identify the Ca(2+)-binding protein S100B as an interacting partner of 5-HT7 and show that S100B negatively regulates inducible cyclic AMP (cAMP) accumulation in transfected HeLa cells and mouse cortical astrocytes. Overexpression of S100B causes brain region-specific dysregulation of the cAMP pathway in vivo, such that concentrations of cAMP in the frontal cortex are higher in S100B transgenic female mice compared to wild-types. Finally, S100B transgenic female mice show depressive-like behavior in the forced swim test (FST) and pharmacological blockade of 5-HT7 with SB269970 normalizes FST behavior. Taken together, our results show that S100B affects behavioral despair in female mice through functional interaction with the 5-HT7 receptor. Furthermore, we identify S100B as a cAMP-regulatory protein in cultured astrocytes and the murine frontal cortex. Future experiments will clarify whether there is a direct link between the 5-HT7-associated and cAMP-regulatory actions of S100B.

  20. Activation of 5-HT7 receptor stimulates neurite elongation through mTOR, Cdc42 and actin filaments dynamics.

    PubMed

    Speranza, Luisa; Giuliano, Teresa; Volpicelli, Floriana; De Stefano, M Egle; Lombardi, Loredana; Chambery, Angela; Lacivita, Enza; Leopoldo, Marcello; Bellenchi, Gian C; di Porzio, Umberto; Crispino, Marianna; Perrone-Capano, Carla

    2015-01-01

    Recent studies have indicated that the serotonin receptor subtype 7 (5-HT7R) plays a crucial role in shaping neuronal morphology during embryonic and early postnatal life. Here we show that pharmacological stimulation of 5-HT7R using a highly selective agonist, LP-211, enhances neurite outgrowth in neuronal primary cultures from the cortex, hippocampus and striatal complex of embryonic mouse brain, through multiple signal transduction pathways. All these signaling systems, involving mTOR, the Rho GTPase Cdc42, Cdk5, and ERK, are known to converge on the reorganization of cytoskeletal proteins that subserve neurite outgrowth. Indeed, our data indicate that neurite elongation stimulated by 5-HT7R is modulated by drugs affecting actin polymerization. In addition, we show, by 2D Western blot analyses, that treatment of neuronal cultures with LP-211 alters the expression profile of cofilin, an actin binding protein involved in microfilaments dynamics. Furthermore, by using microfluidic chambers that physically separate axons from the soma and dendrites, we demonstrate that agonist-dependent activation of 5-HT7R stimulates axonal elongation. Our results identify for the first time several signal transduction pathways, activated by stimulation of 5-HT7R, that converge to promote cytoskeleton reorganization and consequent modulation of axonal elongation. Therefore, the activation of 5-HT7R might represent one of the key elements regulating CNS connectivity and plasticity during development.

  1. 5-HT2 receptor distribution shown by [18F] setoperone PET in high-functioning autistic adults.

    PubMed

    Beversdorf, David Q; Nordgren, Richard E; Bonab, Ali A; Fischman, Alan J; Weise, Steven B; Dougherty, Darin D; Felopulos, Gretchen J; Zhou, Feng C; Bauman, Margaret L

    2012-01-01

    The serotonergic system is implicated in disordered emotional behavior. Autism is characterized by impaired processing of emotional information. The serotonergic (5-HT) system is also critically involved in brain development, and abnormal brain synthesis of serotonin is observed in autism. Furthermore, whole blood and platelet serotonin have been reported to be elevated in autism. The authors examined the CNS serotonin system in autism in vivo. 5-HT2 receptors were visualized by PET imaging of [18F]setoperone-binding in this pilot study of 6 high-functioning autistic adults and 10 matched-control participants. Autism subjects had less thalamic [18F]setoperone binding than controls, when covaried for age, but no difference reached significance in other areas. A negative relationship between thalamic binding and history of language impairment was also observed. Further studies will be needed to gain a clearer picture of the role of the 5-HT system in autism.

  2. Role of maternal 5-HT(1A) receptor in programming offspring emotional and physical development.

    PubMed

    van Velzen, A; Toth, M

    2010-11-01

    Serotonin(1A) receptor (5-HT(1A)R) deficiency has been associated with anxiety and depression and mice with genetic receptor inactivation exhibit heightened anxiety. We have reported that 5-HT(1A)R is not only a genetic but also a maternal 'environmental' factor in the development of anxiety in Swiss-Webster mice. Here, we tested whether the emergence of maternal genotype-dependent adult anxiety is preceded by early behavioral abnormalities or whether it is manifested following a normal emotional development. Pups born to null or heterozygote mothers had significantly reduced ultrasonic vocalization (USV) between postnatal day (P) 4 and 12, indicating an influence of the maternal genotype. The offspring's own genotype had an effect limited to P4. Furthermore, we observed reduced weight gain in the null offspring of null but not heterozygote mothers, indicating that a complete maternal receptor deficiency compromises physical development of the offspring. Except a short perinatal deficit during the dark period, heterozygote females displayed normal maternal behavior, which, with the early appearance of USV deficit, suggests a role for 5-HT(1A)R during pre-/perinatal development. Consistent with this notion, adult anxiety in the offspring is determined during the pre-/perinatal period. In contrast to heterozygote females, null mothers exhibited impaired pup retrieval and nest building that may explain the reduced weight gain of their offspring. Taken together, our data indicate an important role for the maternal 5-HT(1A)R in regulating emotional and physical development of their offspring. Because reduced receptor binding has been reported in depression, including postpartum depression, reduced 5-HT(1A)R function in mothers may influence the emotional development of their offspring.

  3. 5-HT2 receptor blockade exhibits 5-HT vasodilator effects via nitric oxide, prostacyclin and ATP-sensitive potassium channels in rat renal vasculature.

    PubMed

    García-Pedraza, J A; García, M; Martín, M L; Rodríguez-Barbero, A; Morán, A

    2016-04-01

    The aim of this study was to determine whether orally sarpogrelate (selective 5-HT2 antagonist) treatment (30 mg/kg/day; 14 days) could modify 5-HT renal vasoconstrictor responses, characterizing 5-HT receptors and mediator mechanisms involved in serotonergic responses in the in situ autoperfused rat kidney. Intra-arterial (i.a.) injections of 5-HT (0.00000125 to 0.1 μg/kg) decreased renal perfusion pressure (RPP) but did not affect the mean blood pressure (MBP). i.a. agonists 5-CT (5-HT1/7), CGS-12066B (5-HT1B), L-694,247 (5-HT1D) or AS-19 (5-HT7) mimicked renal 5-HT vasodilator effect. However, neither 8-OH-DPAT (5-HT1A) nor 1-phenylbiguanide (5-HT3) modified RPP. Moreover: (i) GR-55562 (5-HT1B antagonist) and L-NAME (nitric oxide synthase [NOS] inhibitor) blocked CGS-12066B-induced vasodilator response, (ii) LY310762 (5-HT1D antagonist) and indomethacin (non-selective cyclooxygenase inhibitor) blocked L-694,247-induced vasodilator response; (iii) SB-258719 (5-HT7 antagonist) and glibenclamide (ATP-sensitive K+ channel blocker) blocked AS-19-induced vasodilator response; and (iv) 5-HT- or 5-CT-elicited renal vasodilation was significantly blocked by the mixture of GR-55562 + LY310762 + SB-258719. Furthermore, eNOS and iNOS proteins and prostacyclin levels are overexpressed in sarpogrelate-treated rats. Our data suggest that 5-HT exerts renal vasodilator effect in the in situ autoperfused sarpogrelate-treated rat kidney, mediated by 5-HT1D, 5-HT1B and 5-HT7 receptors, involving cyclooxygenase-derived prostacyclin, nitric oxide synthesis/release and ATP-sensitive K+ channels, respectively.

  4. N-desalkylquetiapine, a potent norepinephrine reuptake inhibitor and partial 5-HT1A agonist, as a putative mediator of quetiapine's antidepressant activity.

    PubMed

    Jensen, Niels H; Rodriguiz, Ramona M; Caron, Marc G; Wetsel, William C; Rothman, Richard B; Roth, Bryan L

    2008-09-01

    Quetiapine is an atypical antipsychotic drug that is also US FDA approved for treating bipolar depression, albeit by an unknown mechanism. To discover the potential mechanism for this apparently unique action, we screened quetiapine, its metabolite N-Desalkylquetiapine, and dibenzo[b,f][1,4]thiazepine-11(10-H)-one (DBTO) against a large panel of G-protein-coupled receptors, ion channels, and neurotransmitter transporters. DBTO was inactive at all tested molecular targets. N-Desalkylquetiapine had a high affinity (3.4 nM) for the histamine H(1) receptor and moderate affinities (10-100 nM) for the norepinephrine reuptake transporter (NET), the serotonin 5-HT(1A), 5-HT(1E), 5-HT(2A), 5-HT(2B), 5-HT(7) receptors, the alpha(1B)-adrenergic receptor, and the M(1), M(3), and M(5) muscarinic receptors. The compound had low affinities (100-1000 nM) for the 5-HT(1D), 5-HT(2C), 5-HT(3), 5-HT(5), 5-HT(6), alpha(1A), alpha(2A), alpha(2B), alpha(2C), H(2), M(2), M(4), and dopamine D(1), D(2), D(3), and D(4) receptors. N-Desalkylquetiapine potently inhibited human NE transporter with a K(i) of 12 nM, about 100-fold more potent than quetiapine itself. N-Desalkylquetiapine was also 10-fold more potent and more efficacious than quetiapine at the 5-HT(1A) receptor. N-Desalkylquetiapine was an antagonist at 5-HT(2A), 5-HT(2B), 5-HT(2C), alpha(1A), alpha(1D), alpha(2A), alpha(2C), H(1), M(1), M(3), and M(5) receptors. In the mouse tail suspension test, N-Desalkylquetiapine displayed potent antidepressant-like activity in VMAT2 heterozygous mice at doses as low as 0.1 mg/kg. These data strongly suggest that the antidepressant activity of quetiapine is mediated, at least in part, by its metabolite N-Desalkylquetiapine through NET inhibition and partial 5-HT(1A) agonism. Possible contributions of this metabolite to the side effects of quetiapine are discussed.

  5. 5-HT receptors and reward-related behaviour: a review.

    PubMed

    Hayes, Dave J; Greenshaw, Andrew J

    2011-05-01

    The brain's serotonin (5-HT) system is key in the regulation of reward-related behaviours, from eating and drinking to sexual activity. The complexity of studying this system is due, in part, to the fact that 5-HT acts at many receptor subtypes throughout the brain. The recent development of drugs with greater selectivity for individual receptor subtypes has allowed for rapid advancements in our understanding of this system. Use of these drugs in combination with animal models entailing selective reward measures (i.e. intracranial self-stimulation, drug self-administration, conditioned place preference) have resulted in a greater understanding of the pharmacology of reward-related processing and behaviour (particularly regarding drugs of abuse). The putative roles of each 5-HT receptor subtype in the pharmacology of reward are outlined and discussed here. It is concluded that the actions of 5-HT in reward are receptor subtype-dependent (and thus should not be generalized) and that all studied subtypes appear to have a unique profile which is determined by content (e.g. receptor function, localization - both throughout the brain and within the synapse) and context (e.g. type of behavioural paradigm, type of drug). Given evidence of altered reward-related processing and serotonergic function in numerous neuropsychiatric disorders, such as depression, schizophrenia, and addiction, a clearer understanding of the role of 5-HT receptor subtypes in this context may lead to improved drug development and therapeutic approaches.

  6. Serotonin Transporter and Receptor Expression in Osteocytic MLO-Y4 Cells

    PubMed Central

    BLIZIOTES, M.; ESHLEMAN, A.; BURT-PICHAT, B.; ZHANG, X.-W.; HASHIMOTO, J.; WIREN, K.; CHENU, C.

    2006-01-01

    Neurotransmitter regulation of bone metabolism has been a subject of increasing interest and investigation. We reported previously that osteoblastic cells express a functional serotonin (5-HT) signal transduction system, with mechanisms for responding to and regulating uptake of 5-HT. The clonal murine osteocytic cell line, MLO-Y4, demonstrates expression of the serotonin transporter (5-HTT), and the 5-HT1A, and 5-HT2A receptors by real-time RT-PCR and immunoblot analysis. Immunohistochemistry using antibodies for the 5-HTT, and the 5-HT1A and 5-HT2A receptors reveals expression of all three proteins in both osteoblasts and osteocytes in rat tibia. 5-HTT binding sites were demonstrated in the MLO-Y4 cells with nanomolar affinity for the stable cocaine analog [125I]RTI-55. Imipramine and fluoxetine, antagonists with specificity for 5-HTT, show the highest potency to antagonize [125I]RTI-55 binding in the MLO-Y4 cells. GBR-12935, a relatively selective dopamine transporter antagonist, had a much lower potency, as did desipramine, a selective norepinephrine transporter antagonist. The maximal [3H]5-HT uptake rate in MLO-Y4 cells was 2.85 pmol/15 min/well, with a Km value of 290 nM. Imipramine and fluoxetine inhibited specific [3H]5-HT uptake with IC50 values in the nanomolar range. 5-HT rapidly stimulated PGE2 release from MLO-Y4 cells; the EC50 for 5-HT was 0.1 μM, with a 3-fold increase seen at 60 min. The rate limiting enzyme for serotonin synthesis, tryptophan hydroxylase, is expressed in MLO-Y4 cells as well as osteoblastic MC3T3-E1 cells. Thus, osteocytes, as well as osteoblasts, are capable of 5-HT synthesis, and express functional receptor and transporter components of the 5-HT signal transduction system. PMID:16884969

  7. Role of spinal 5-HT5A, and 5-HT1A/1B/1D, receptors in neuropathic pain induced by spinal nerve ligation in rats.

    PubMed

    Avila-Rojas, Sabino Hazael; Velázquez-Lagunas, Isabel; Salinas-Abarca, Ana Belen; Barragán-Iglesias, Paulino; Pineda-Farias, Jorge Baruch; Granados-Soto, Vinicio

    2015-10-05

    Serotonin (5-HT) participates in pain modulation by interacting with different 5-HT receptors. The role of 5-HT5A receptor in neuropathic pain has not previously studied. The purpose of this study was to investigate: A) the role of 5-HT5A receptors in rats subjected to spinal nerve injury; B) the expression of 5-HT5A receptors in dorsal spinal cord and dorsal root ganglia (DRG). Neuropathic pain was induced by L5/L6 spinal nerve ligation. Tactile allodynia in neuropathic rats was assessed with von Frey filaments. Western blot methodology was used to determine 5-HT5A receptor protein expression. Intrathecal administration (on day 14th) of 5-HT (10-100 nmol) or 5-carboxamidotryptamine (5-CT, 0.03-0.3 nmol) reversed nerve injury-induced tactile allodynia. Intrathecal non-selective (methiothepin, 0.1-0.8 nmol) and selective (SB-699551, 1-10 nmol) 5-HT5A receptor antagonists reduced, by ~60% and ~25%, respectively, the antiallodynic effect of 5-HT (100 nmol) or 5-CT (0.3 nmol). Moreover, both selective 5-HT1A and 5-HT1B/1D receptor antagonists, WAY-100635 (0.3-1 nmol) and GR-127935 (0.3-1 nmol), respectively, partially diminished the antiallodynic effect of 5-HT or 5-CT by about 30%. Injection of antagonists, by themselves, did not affect allodynia. 5-HT5A receptors were expressed in the ipsilateral dorsal lumbar spinal cord and DRG and L5/L6 spinal nerve ligation did not modify 5-HT5A receptor protein expression in those sites. Results suggest that 5-HT5A receptors reduce pain processing in the spinal cord and that 5-HT and 5-CT reduce neuropathic pain through activation of 5-HT5A and 5-HT1A/1B/1D receptors. These receptors could be an important part of the descending pain inhibitory system.

  8. The role of the serotonin receptor subtypes 5-HT1A and 5-HT7 and its interaction in emotional learning and memory

    PubMed Central

    Stiedl, Oliver; Pappa, Elpiniki; Konradsson-Geuken, Åsa; Ögren, Sven Ove

    2015-01-01

    Serotonin [5-hydroxytryptamine (5-HT)] is a multifunctional neurotransmitter innervating cortical and limbic areas involved in cognition and emotional regulation. Dysregulation of serotonergic transmission is associated with emotional and cognitive deficits in psychiatric patients and animal models. Drugs targeting the 5-HT system are widely used to treat mood disorders and anxiety-like behaviors. Among the fourteen 5-HT receptor (5-HTR) subtypes, the 5-HT1AR and 5-HT7R are associated with the development of anxiety, depression and cognitive function linked to mechanisms of emotional learning and memory. In rodents fear conditioning and passive avoidance (PA) are associative learning paradigms to study emotional memory. This review assesses the role of 5-HT1AR and 5-HT7R as well as their interplay at the molecular, neurochemical and behavioral level. Activation of postsynaptic 5-HT1ARs impairs emotional memory through attenuation of neuronal activity, whereas presynaptic 5-HT1AR activation reduces 5-HT release and exerts pro-cognitive effects on PA retention. Antagonism of the 5-HT1AR facilitates memory retention possibly via 5-HT7R activation and evidence is provided that 5HT7R can facilitate emotional memory upon reduced 5-HT1AR transmission. These findings highlight the differential role of these 5-HTRs in cognitive/emotional domains of behavior. Moreover, the results indicate that tonic and phasic 5-HT release can exert different and potentially opposing effects on emotional memory, depending on the states of 5-HT1ARs and 5-HT7Rs and their interaction. Consequently, individual differences due to genetic and/or epigenetic mechanisms play an essential role for the responsiveness to drug treatment, e.g., by SSRIs which increase intrasynaptic 5-HT levels thereby activating multiple pre- and postsynaptic 5-HTR subtypes. PMID:26300776

  9. The role of the serotonin receptor subtypes 5-HT1A and 5-HT7 and its interaction in emotional learning and memory.

    PubMed

    Stiedl, Oliver; Pappa, Elpiniki; Konradsson-Geuken, Åsa; Ögren, Sven Ove

    2015-01-01

    Serotonin [5-hydroxytryptamine (5-HT)] is a multifunctional neurotransmitter innervating cortical and limbic areas involved in cognition and emotional regulation. Dysregulation of serotonergic transmission is associated with emotional and cognitive deficits in psychiatric patients and animal models. Drugs targeting the 5-HT system are widely used to treat mood disorders and anxiety-like behaviors. Among the fourteen 5-HT receptor (5-HTR) subtypes, the 5-HT1AR and 5-HT7R are associated with the development of anxiety, depression and cognitive function linked to mechanisms of emotional learning and memory. In rodents fear conditioning and passive avoidance (PA) are associative learning paradigms to study emotional memory. This review assesses the role of 5-HT1AR and 5-HT7R as well as their interplay at the molecular, neurochemical and behavioral level. Activation of postsynaptic 5-HT1ARs impairs emotional memory through attenuation of neuronal activity, whereas presynaptic 5-HT1AR activation reduces 5-HT release and exerts pro-cognitive effects on PA retention. Antagonism of the 5-HT1AR facilitates memory retention possibly via 5-HT7R activation and evidence is provided that 5HT7R can facilitate emotional memory upon reduced 5-HT1AR transmission. These findings highlight the differential role of these 5-HTRs in cognitive/emotional domains of behavior. Moreover, the results indicate that tonic and phasic 5-HT release can exert different and potentially opposing effects on emotional memory, depending on the states of 5-HT1ARs and 5-HT7Rs and their interaction. Consequently, individual differences due to genetic and/or epigenetic mechanisms play an essential role for the responsiveness to drug treatment, e.g., by SSRIs which increase intrasynaptic 5-HT levels thereby activating multiple pre- and postsynaptic 5-HTR subtypes.

  10. Physiological, pathophysiological and therapeutic roles of 5-HT systems in learning and memory.

    PubMed

    Meneses, A

    1998-01-01

    Multiple 5-hydroxytryptamine (5-HT) receptors have been identified (5-HT1A/1B/1D/1E/1F, 5-HT2A/2B/2C, 5-HT3A/3B, 5-HT4A/4B, 5-HT5A/5B, 5-HT6 and 5-HT7A/7B/7C/7D) and extensive evidence suggests that 5-HT receptors have a role in learning and memory. Indeed, available evidence strongly supports physiological, pathophysiological and therapeutic roles of 5-HT systems in cognitive processes, although the evidence seems incomplete. Indeed, there has been a clear tendency to use pre-learning administration most frequently, whereas post-learning and pre-retention administration protocols have been utilized in only a few studies, and probably this trend has led to missed relevant information. For instance, when pre- vs post-training administration of 5-HT1A agonist, 5-HT2 antagonists and 5-HT4 agonists have been compared contrasting findings were reported in aversive and appetitive learning tasks. Emerging evidence also indicates that 5-HT1A and 5-HT4 receptor agonists, as well as, 5-HT1A antagonists, 5-HT2 antagonists, 5-HT3 antagonists and 5-HT uptake inhibitors may have therapeutic utility in the treatment of Alzheimer's disease and amnesia. Inasmuch as the activation or blockade of diverse 5-HT receptors is able to modulate cognitive processes, and 5-HT uptake inhibition could have therapeutic applications in the treatment of cognitive disorders, it seems evident that the role of 5-HT in learning and memory is more complex than a simple imbalance. Consequently, the notion that activation of the 5-HT systems impairs performance, whereas reduced serotonergic function may facilitate learning, must be reconsidered.

  11. Vortioxetine dose-dependently reverses 5-HT depletion-induced deficits in spatial working and object recognition memory: a potential role for 5-HT1A receptor agonism and 5-HT3 receptor antagonism.

    PubMed

    du Jardin, Kristian Gaarn; Jensen, Jesper Bornø; Sanchez, Connie; Pehrson, Alan L

    2014-01-01

    We previously reported that the investigational multimodal antidepressant, vortioxetine, reversed 5-HT depletion-induced memory deficits while escitalopram and duloxetine did not. The present report studied the effects of vortioxetine and the potential impact of its 5-HT1A receptor agonist and 5-HT3 receptor antagonist properties on 5-HT depletion-induced memory deficits. Recognition and spatial working memory were assessed in the object recognition (OR) and Y-maze spontaneous alternation (SA) tests, respectively. 5-HT depletion was induced in female Long-Evans rats using 4-cholro-DL-phenylalanine methyl ester HCl (PCPA) and receptor occupancies were determined by ex vivo autoradiography. Rats were acutely dosed with vortioxetine, ondansetron (5-HT3 receptor antagonist) or flesinoxan (5-HT1A receptor agonist). The effects of chronic vortioxetine administration on 5-HT depletion-induced memory deficits were also assessed. 5-HT depletion reliably impaired memory performance in both the tests. Vortioxetine reversed PCPA-induced memory deficits dose-dependently with a minimal effective dose (MED) ≤0.1mg/kg (∼80% 5-HT3 receptor occupancy; OR) and ≤3.0mg/kg (5-HT1A, 5-HT1B, 5-HT3 receptor occupancy: ∼15%, 60%, 95%) in SA. Ondansetron exhibited a MED ≤3.0μg/kg (∼25% 5-HT3 receptor occupancy; OR), but was inactive in the SA test. Flesinoxan had a MED ≤1.0mg/kg (∼25% 5-HT1A receptor occupancy; SA); only 1.0mg/kg ameliorated deficits in the NOR. Chronic p.o. vortioxetine administration significantly improved memory performance in OR and occupied 95%, 66%, and 9.5% of 5-HT3, 5-HT1B, and 5-HT1A receptors, respectively. Vortioxetine's effects on SA performance may involve 5-HT1A receptor agonism, but not 5-HT3 receptor antagonism, whereas the effects on OR performance may involve 5-HT3 receptor antagonism and 5-HT1A receptor agonism.

  12. Repeated lysergic acid diethylamide in an animal model of depression: Normalisation of learning behaviour and hippocampal serotonin 5-HT2 signalling.

    PubMed

    Buchborn, Tobias; Schröder, Helmut; Höllt, Volker; Grecksch, Gisela

    2014-06-01

    A re-balance of postsynaptic serotonin (5-HT) receptor signalling, with an increase in 5-HT1A and a decrease in 5-HT2A signalling, is a final common pathway multiple antidepressants share. Given that the 5-HT1A/2A agonist lysergic acid diethylamide (LSD), when repeatedly applied, selectively downregulates 5-HT2A, but not 5-HT1A receptors, one might expect LSD to similarly re-balance the postsynaptic 5-HT signalling. Challenging this idea, we use an animal model of depression specifically responding to repeated antidepressant treatment (olfactory bulbectomy), and test the antidepressant-like properties of repeated LSD treatment (0.13 mg/kg/d, 11 d). In line with former findings, we observe that bulbectomised rats show marked deficits in active avoidance learning. These deficits, similarly as we earlier noted with imipramine, are largely reversed by repeated LSD administration. Additionally, bulbectomised rats exhibit distinct anomalies of monoamine receptor signalling in hippocampus and/or frontal cortex; from these, only the hippocampal decrease in 5-HT2 related [(35)S]-GTP-gamma-S binding is normalised by LSD. Importantly, the sham-operated rats do not profit from LSD, and exhibit reduced hippocampal 5-HT2 signalling. As behavioural deficits after bulbectomy respond to agents classified as antidepressants only, we conclude that the effect of LSD in this model can be considered antidepressant-like, and discuss it in terms of a re-balance of hippocampal 5-HT2/5-HT1A signalling.

  13. Selective 5-HT7 Receptor Activation May Enhance Synaptic Plasticity Through N-methyl-D-aspartate (NMDA) Receptor Activity in the Visual Cortex.

    PubMed

    Xiang, Kangjian; Zhao, Xuefei; Li, Youjun; Zheng, Liang; Wang, Jue; Li, Yan-Hai

    2016-01-01

    Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter that modulates N-methyl-D-aspartate (NMDA) receptor activity by binding to several different 5-HT receptor subtypes. In the present study, we used whole-cell patch-clamp recordings in transverse slice preparations to test the role of 5-HT receptors in modulating the NMDA receptor-mediated miniature excitatory postsynaptic currents (mEPSCs) in layer II/III pyramidal neurons of the rat visual cortex. We found that the NMDA receptor-mediated component of mEPSCs could be potentiated by exogenously applied 5-HT. Similar results were obtained by exogenously applied 5-CT or 8-OH-DPAT (the 5-HT1A and 5-HT7 receptor agonist). A specific antagonist for the 5-HT7 receptor, SB-269970, completely blocked the increase in NMDA receptor-mediated component of mEPSCs by 5-CT or 8- OH-DPAT. Moreover, the selective 5-HT1A receptor antagonist, WAY-100135, displayed no influence on the enhancement in NMDA receptor-mediated component of mEPSCs by 5-CT or 8-OHDPAT. These results indicated that the increase in NMDA receptor-mediated component of mEPSCs by 5-HT in layer II/III pyramidal neurons of the young rat visual cortex requires activation of 5-HT7 receptors, but not 5-HT1A receptors. These observations might be clinically relevant to schizophrenia and Alzheimer's disease (AD), where enhancing NMDA receptor-mediated neurotransmission is considered to be a promising strategy for treatment of these diseases.

  14. Important messages in the 'post': recent discoveries in 5-HT neurone feedback control.

    PubMed

    Sharp, Trevor; Boothman, Laura; Raley, Josie; Quérée, Philip

    2007-12-01

    The neurotransmitter 5-hydroxytryptamine (5-HT, serotonin) mediates important brain functions and contributes to the pathophysiology and successful drug treatment of many common psychiatric disorders, especially depression. It is established that a key mechanism involved in the control of 5-HT neurones is feedback inhibition by presynaptic 5-HT autoreceptors, which are located on 5-HT cell bodies and nerve terminals. However, recent experiments have discovered an unexpected complexity of 5-HT neurone control, specifically in the form of postsynaptic 5-HT feedback mechanisms. These mechanisms have the physiological effects of 5-HT autoreceptors but use additional 5-HT receptor subtypes and operate through neural inputs to 5-HT neurones. A postsynaptic feedback system that excites 5-HT neurones has also been reported. This article discusses current knowledge of the pharmacology and physiology of these new found 5-HT feedback mechanisms and considers their possible contribution to depression pathophysiology and utility as a resource of novel antidepressant drug strategies.

  15. Design, synthesis, and biological evaluation of new 5-HT4 receptor agonists: application as amyloid cascade modulators and potential therapeutic utility in Alzheimer's disease.

    PubMed

    Russo, Olivier; Cachard-Chastel, Marthe; Rivière, Céline; Giner, Mireille; Soulier, Jean-Louis; Berthouze, Magali; Richard, Tristan; Monti, Jean-Pierre; Sicsic, Sames; Lezoualc'h, Frank; Berque-Bestel, Isabelle

    2009-04-23

    Serotonin 5-HT(4) receptor (5-HT(4)R) agonists are of particular interest for the treatment of Alzheimer's disease because of their ability to ameliorate cognitive deficits and to modulate production of amyloid beta-protein (Abeta). However, despite the range of 5-HT(4)R agonists synthesized to date, potent and selective 5-HT(4)R agonists are still lacking. In the present study, two libraries of molecules based on the scaffold of ML10302, a highly specific and partial 5-HT(4)R agonist, were efficiently prepared by parallel supported synthesis and their binding affinities and agonist activities evaluated. Furthermore, we showed that, in vivo, the two best candidates exhibited neuroprotective activity by increasing the level of the soluble form of the amyloid precursor protein (sAPPalpha) in the cortex and hippocampus of mice. Interestingly, one of these compounds could also inhibit Abeta fibril formation in vitro.

  16. Synthesis and evaluation of 1-[2-(4-[(11)C]methoxyphenyl)phenyl]piperazine for imaging of the serotonin 5-HT7 receptor in the rat brain.

    PubMed

    Shimoda, Yoko; Yui, Joji; Xie, Lin; Fujinaga, Masayuki; Yamasaki, Tomoteru; Ogawa, Masanao; Nengaki, Nobuki; Kumata, Katsushi; Hatori, Akiko; Kawamura, Kazunori; Zhang, Ming-Rong

    2013-09-01

    1-[2-(4-Methoxyphenyl)phenyl]piperazine (4) is a potent serotonin 5-HT7 receptor antagonist (Ki=2.6nM) with a low binding affinity for the 5-HT1A receptor (Ki=476nM). As a potential positron emission tomography (PET) radiotracer for the 5-HT7 receptor, [(11)C]4 was synthesized at high radiochemical yield and specific activity, by O-[(11)C]methylation of 2'-(piperazin-1-yl)-[1,1'-biphenyl]-4-ol (6) with [(11)C]methyl iodide. Autoradiography revealed that [(11)C]4 showed in vitro specific binding with 5-HT7 in the rat brain regions, such as the thalamus which is a region with high 5-HT7 expression. Metabolite analysis indicated that intact [(11)C]4 in the brain exceeded 90% of the radioactive components at 15min after the radiotracer injection, although two radiolabeled metabolites were found in the rat plasma. The PET study of rats showed moderated uptake of [(11)C]4 in the brain (1.2SUV), but no significant regional difference in radioactivity in the brain. Pretreatment with 5-HT7-selective antagonist SB269970 (3) did not decrease the uptake of [(11)C]4 in the rat brain. Further studies are warranted that focus on the development of PET ligand candidates with higher binding affinity for 5-HT7 and higher in vivo stability in brain than 4.

  17. [Medical economics evaluation of 5-HT3 receptor antagonist drugs].

    PubMed

    Utsunomiya, Junpei; Hirano, Shigeki; Fukui, Aiko; Funabashi, Kazuaki; Deguchi, Yuko; Yamada, Susumu; Naito, Kazuyuki

    2010-10-01

    At Komaki City Hospital, the drug cost in connection with cancer chemotherapy was re-examined as part of improved management along with the introduction of DPC in July 2008. With due attention to the 5-HT3 receptor antagonists, both the change from injections to oral drugs and the change from brand-name drugs to generic drugs were tried between July 2008 and June 2009. After that, in order to examine the economic impact of these changes, we investigated and analyzed the number of medications, the cost of medicine purchased, and the average drug cost per medication of the 5-HT3 receptor antagonists between April 2008 and September 2009. As a result, the cost of 5-HT3 receptor antagonists purchased decreased greatly, and the impact of the improvement was mainly due to the change to oral drugs, and partially to the change to generic drugs. Therefore, from the viewpoint of hospital economic improvement in DPC, it was thought that the change to oral drugs(5-HT3 receptor antagonists)is given top priority.

  18. QGP-1 cells release 5-HT via TRPA1 activation; a model of human enterochromaffin cells.

    PubMed

    Doihara, Hitoshi; Nozawa, Katsura; Kojima, Ryosuke; Kawabata-Shoda, Eri; Yokoyama, Toshihide; Ito, Hiroyuki

    2009-11-01

    Recently, we discovered that transient receptor potential ankyrin1 channel (TRPA1) is highly expressed in human and rat enterochromaffin (EC) cells, and those TRPA1 agonists such as allyl isothiocyanates (AITC) and cinnamaldehyde (CA) enhance the release of serotonin (5-hydroxytryptamine; 5-HT) from EC cells in vitro. In this study, QGP-1 cells, a human pancreatic endocrine cell line, were found to highly express TRPA1 and EC cell marker genes, such as tryptophan hydroxylase 1 (TPH1), chromogranin A (CgA), synaptophysin, ATP-dependent vesicular monoamine transporter 1 (VMAT1), metabotropic glutamate receptor 4 (mGluR4), beta1-adrenergic receptor (ADB1), muscarinic 4 acetylcholine receptor (ACM4), substance P, serotonin transporter (SERT), and guanylin. Furthermore, the TRPA1 agonists AITC, CA, and acrolein concentration dependently evoked an increase in intracellular Ca(2+) influx and the release of 5-HT in QGP-1 cells. The effects of these TRPA1 agonists were inhibited by ruthenium red, a TRPA1 antagonist, and TRPA1-specific siRNA. These results indicate that the Ca(2+) influx increase and 5-HT release induced by AITC, CA and acrolein in QGP-1 cells were mediated by TRPA1, and that the QGP-1 cell line could be a new model for the investigation of TRPA1 function in the human EC cell.

  19. Evidence for 5-HT1B/1D and 5-HT2A receptors mediating constriction of the canine internal carotid circulation

    PubMed Central

    Centurión, David; Ortiz, Mario I; Sánchez-López, Araceli; De Vries, Peter; Saxena, Pramod R; Villalón, Carlos M

    2001-01-01

    The present study has investigated the preliminary pharmacological profile of the receptors mediating vasoconstriction to 5-hydroxytryptamine (5-HT) in the internal carotid bed of vagosympathectomised dogs. One minute intracarotid infusions of the agonists 5-HT (0.1–10 μg min−1), sumatriptan (0.3–10 μg min−1; 5-HT1B/1D), 5-methoxytryptamine (1–100 μg min−1; 5-HT1, 5-HT2, 5-HT4, 5-ht6 and 5-HT7) or DOI (0.31–10 μg min−1; 5-HT2), but not 5-carboxamidotryptamine (0.01–0.3 μg min−1; 5-HT1, 5-ht5A and 5-HT7), 1-(m-chlorophenyl)-biguanide (mCPBG; 1–1000 μg min−1; 5-HT3) or cisapride (1–1000 μg min−1; 5-HT4), resulted in dose-dependent decreases in internal carotid blood flow, without changing blood pressure or heart rate. The vasoconstrictor responses to 5-HT, which remained unaffected after saline, were resistant to blockade by i.v. administration of the antagonists ritanserin (100 μg kg−1; 5-HT2A/2B/2C) in combination with tropisetron (3000 μg kg−1; 5-HT3/4) or the cyclo-oxygenase inhibitor, indomethacin (5000 μg kg−1), but were abolished by the 5-HT1B/1D receptor antagonist, GR127935 (30 μg kg−1). Interestingly, after administration of GR127935, the subsequent administration of ritanserin unmasked a dose-dependent vasodilator component. GR127935 or saline did not practically modify the vasoconstrictor effects of 5-MeO-T. In animals receiving GR127935, the subsequent administration of ritanserin abolished the vasoconstrictor responses to 5-MeO-T unmasking a dose-dependent vasodilator component. The vasoconstriction induced by sumatriptan was antagonized by GR127935, but not by ritanserin. Furthermore, ritanserin (100 μg kg−1) or ketanserin (100 μg kg−1; 5-HT2A), but not GR127935, abolished DOI-induced vasoconstrictor responses. The above results suggest that 5-HT-induced internal carotid vasoconstriction is predominantly mediated by 5-HT1B/1D and 5-HT2A receptors

  20. The 5-HT[subscript 3A] Receptor Is Essential for Fear Extinction

    ERIC Educational Resources Information Center

    Kondo, Makoto; Nakamura, Yukiko; Ishida, Yusuke; Yamada, Takahiro; Shimada, Shoichi

    2014-01-01

    The 5-HT [subscript 3] receptor, the only ionotropic 5-HT receptor, is expressed in limbic regions, including the hippocampus, amygdala, and cortex. However, it is not known whether it has a role in fear memory processes. Analysis of 5-HT [subscript 3A] receptor knockout mice in fear conditioning paradigms revealed that the 5-HT [subscript 3A]…

  1. 5-HT2CRs expressed by pro-opiomelanocortin neurons regulate insulin sensitivity in liver

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mice lacking 5-HT 2C receptors displayed hepatic insulin resistance, a phenotype normalized by re-expression of 5-HT2CRs only in pro-opiomelanocortin (POMC) neurons. 5-HT2CR deficiency also abolished the anti-diabetic effects of meta-chlorophenylpiperazine (a 5-HT2CR agonist); these effects were re...

  2. Serotonin modifies the spontaneous spiking activity of gracile nucleus neurons in rats: role of 5-HT1A and 5-HT2 receptors.

    PubMed

    Grasso, C; Li Volsi, G; Barresi, M

    2016-06-01

    We tested the effects of microiontophoretic application of serotonin (5-HT) on the firing rate of neurons located in the gracile nucleus (GN) of rats. Application of 5-HT1A and 5-HT2 agonists and antagonists respectively mimicked/ modulated and blocked the effects produced by the amine, respectively. Among the tested neurons, 88.2% modified their background firing activity in the presence of 5-HT. Responsive neurons decreased their mean firing activity (MFA) in 56.7% of cases and increased it in the remaining 43.3%. To ascertain the specificity of the effects induced by 5-HT, we utilized 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) and alpha-methyl-5-hydroxytryptamine (α-MET-5-HT), agonists for 5-HT1A and 5-HT2 receptors, respectively. The microiontophoresis of 8-OH-DPAT modified the background firing rate of all GN neurons (100% of tested neurons) mimicking the decrease of MFA evoked by 5-HT. The application of a-MET-5-HT modified the MFA in 76.9% of tested neurons, decreasing it in 61.5% of cases and increasing in the remaining 23.1%. The decrease of MFA induced by 8-OH-DPAT was antagonized by application of the 5-HT1A receptor antagonist N-[2-[-(2-Methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate salt (WAY100635), while application of 5-HT2 receptor antagonist ketanserine tartrate (KET) antagonized only the increase of MFA induced by a-MET-5-HT. These results indicate that 5-HT is able to modulate the background firing activity of GN neurons by 5-HT1A and 5-HT2 receptors.

  3. The Pharmacology of TD-8954, a Potent and Selective 5-HT4 Receptor Agonist with Gastrointestinal Prokinetic Properties

    PubMed Central

    Beattie, David T.; Armstrong, Scott R.; Vickery, Ross G.; Tsuruda, Pamela R.; Campbell, Christina B.; Richardson, Carrie; McCullough, Julia L.; Daniels, Oranee; Kersey, Kathryn; Li, Yu-Ping; Kim, Karl H. S.

    2011-01-01

    This study evaluated the in vitro and in vivo pharmacological properties of TD-8954, a potent and selective 5-HT4 receptor agonist. TD-8954 had high affinity (pKi = 9.4) for human recombinant 5-HT4(c) (h5-HT4(c)) receptors, and selectivity (>2,000-fold) over all other 5-hydroxytryptamine (5-HT) receptors and non-5-HT receptors, ion channels, enzymes and transporters tested (n = 78). TD-8954 produced an elevation of cAMP in HEK-293 cells expressing the h5-HT4(c) receptor (pEC50 = 9.3), and contracted the guinea pig colonic longitudinal muscle/myenteric plexus preparation (pEC50 = 8.6). TD-8954 had moderate intrinsic activity in the in vitro assays. In conscious guinea pigs, subcutaneous administration of TD-8954 (0.03–3 mg/kg) increased the colonic transit of carmine red dye, reducing the time taken for its excretion. Following intraduodenal dosing to anesthetized rats, TD-8954 (0.03–10 mg/kg) evoked a dose-dependent relaxation of the esophagus. Following oral administration to conscious dogs, TD-8954 (10 and 30 μg/kg) produced an increase in contractility of the antrum, duodenum, and jejunum. In a single ascending oral dose study in healthy human subjects, TD-8954 (0.1–20 mg) increased bowel movement frequency and reduced the time to first stool. It is concluded that TD-8954 is a potent and selective 5-HT4 receptor agonist in vitro, with robust in vivo stimulatory activity in the gastrointestinal (GI) tract of guinea pigs, rats, dogs, and humans. TD-8954 may have clinical utility in patients with disorders of reduced GI motility. PMID:21687517

  4. Long-term Stress with Hyperglucocorticoidemia-induced Hepatic Steatosis with VLDL Overproduction Is Dependent on both 5-HT2 Receptor and 5-HT Synthesis in Liver

    PubMed Central

    Fu, Jihua; Ma, Shaoxin; Li, Xin; An, Shanshan; Li, Tao; Guo, Keke; Lin, Min; Qu, Wei; Wang, Shanshan; Dong, Xinyue; Han, Xiaoyu; Fu, Ting; Huang, Xinping; Wang, Tianying; He, Siyu

    2016-01-01

    Hepatic triglycerides production and adipose lipolysis are pivotal for long-term stress (LTS) or hyperglucocorticoidemia-induced insulin resistance. 5-hydroxytryptamine (5-HT) has been demonstrated to induce hepatic lipid metabolic abnormality by activating mammalian target of rapamycin (mTOR). In present study, we explored whether 5-HT is involved in LTS effects in liver using restraint stress-exposed rats and cultured primary rat hepatocytes and HepG2 cells. LTS with hyperglucocorticoidemia induced hepatic 5-HT synthetic increase with tryptophan hydroxylase 1 (Tph1) up-regulation, and 5-HT2 receptor (5-HT2R, including 5-HT2A, 2B receptor) up-regulation in liver and visceral adipose, as well as hepatic mTOR activation with triglycerides and VLDL overproduction with steatosis, and visceral adipose lipolytic increase with high blood free fatty acids (FFAs) level. 5-HT exposure exhibited LTS-like effects in both tissues, and both LTS and 5-HT effects could be abolished significantly by blocking 5-HT2R. In HepG2 cells dexamethasone or palmitate-induced mTOR activation with triglycerides and VLDL overproduction were accompanied by up-regulations of 5-HT synthesis and 5-HT2R, which were significantly abolished by gene silencing Tph1 or 5-HT2R and were almost fully abolished by co-silencing of both, especially on VLDL overproduction. Chemical inhibition of Tph1 or/and 5-HT2R in both hepatocytes exhibited similar abolishment with genetic inhibition on dexamethason-induced effects. 5-HT-stimulated effects in both hepatocytes were fully abolished by blocking 5-HT2R, while 5-HT itself also up-regulated 5-HT2R. In conclusion, up-regulated hepatic 5-HT synthesis and 5-HT2R induced by both glucocorticoid and FFAs are crucial for LTS-induced hepatic steatosis with VLDL overproduction, while 5-HT by acting on 5-HT2R mediates mTOR activation in liver. PMID:26884719

  5. Long-term Stress with Hyperglucocorticoidemia-induced Hepatic Steatosis with VLDL Overproduction Is Dependent on both 5-HT2 Receptor and 5-HT Synthesis in Liver.

    PubMed

    Fu, Jihua; Ma, Shaoxin; Li, Xin; An, Shanshan; Li, Tao; Guo, Keke; Lin, Min; Qu, Wei; Wang, Shanshan; Dong, Xinyue; Han, Xiaoyu; Fu, Ting; Huang, Xinping; Wang, Tianying; He, Siyu

    2016-01-01

    Hepatic triglycerides production and adipose lipolysis are pivotal for long-term stress (LTS) or hyperglucocorticoidemia-induced insulin resistance. 5-hydroxytryptamine (5-HT) has been demonstrated to induce hepatic lipid metabolic abnormality by activating mammalian target of rapamycin (mTOR). In present study, we explored whether 5-HT is involved in LTS effects in liver using restraint stress-exposed rats and cultured primary rat hepatocytes and HepG2 cells. LTS with hyperglucocorticoidemia induced hepatic 5-HT synthetic increase with tryptophan hydroxylase 1 (Tph1) up-regulation, and 5-HT2 receptor (5-HT2R, including 5-HT2A, 2B receptor) up-regulation in liver and visceral adipose, as well as hepatic mTOR activation with triglycerides and VLDL overproduction with steatosis, and visceral adipose lipolytic increase with high blood free fatty acids (FFAs) level. 5-HT exposure exhibited LTS-like effects in both tissues, and both LTS and 5-HT effects could be abolished significantly by blocking 5-HT2R. In HepG2 cells dexamethasone or palmitate-induced mTOR activation with triglycerides and VLDL overproduction were accompanied by up-regulations of 5-HT synthesis and 5-HT2R, which were significantly abolished by gene silencing Tph1 or 5-HT2R and were almost fully abolished by co-silencing of both, especially on VLDL overproduction. Chemical inhibition of Tph1 or/and 5-HT2R in both hepatocytes exhibited similar abolishment with genetic inhibition on dexamethason-induced effects. 5-HT-stimulated effects in both hepatocytes were fully abolished by blocking 5-HT2R, while 5-HT itself also up-regulated 5-HT2R. In conclusion, up-regulated hepatic 5-HT synthesis and 5-HT2R induced by both glucocorticoid and FFAs are crucial for LTS-induced hepatic steatosis with VLDL overproduction, while 5-HT by acting on 5-HT2R mediates mTOR activation in liver.

  6. Novel and Potent 5-Piperazinyl Methyl-N 1-aryl Sulfonyl Indole Derivatives as 5-HT6 Receptor Ligands.

    PubMed

    Nirogi, Ramakrishna V S; Kothmirkar, Prabhakar; Kambhampati, Ramasastri; Konda, Jagadish Babu; Arepalli, Sobhanadri; Pamuleti, Narasimhareddy G; Deshpande, Amol D; Bandyala, Trinathreddy; Shinde, Anil K; Dubey, P K

    2010-10-14

    The exclusive distribution of 5-HT6 receptors in the brain regions associated with learning and memory makes it an ideal target for cognitive disorders. A novel series of 5-piperazinyl methyl-N 1-aryl sulfonyl indoles were designed and synthesized as 5-HT6R ligands. Most of the synthesized compounds are potent when tested by in vitro radioligand binding assay. The lead compound from the series does not have the CYP liabilities and is active in an animal model of cognition.

  7. Downregulation of 5-HT7 Serotonin Receptors by the Atypical Antipsychotics Clozapine and Olanzapine. Role of Motifs in the C-Terminal Domain and Interaction with GASP-1.

    PubMed

    Manfra, Ornella; Van Craenenbroeck, Kathleen; Skieterska, Kamila; Frimurer, Thomas; Schwartz, Thue W; Levy, Finn Olav; Andressen, Kjetil Wessel

    2015-07-15

    The human 5-HT7 serotonin receptor, a G-protein-coupled receptor (GPCR), activates adenylyl cyclase constitutively and upon agonist activation. Biased ligands differentially activate 5-HT7 serotonin receptor desensitization, internalization and degradation in addition to G protein activation. We have previously found that the atypical antipsychotics clozapine and olanzapine inhibited G protein activation and, surprisingly, induced both internalization and lysosomal degradation of 5-HT7 receptors. Here, we aimed to determine the mechanism of clozapine- and olanzapine-mediated degradation of 5-HT7 receptors. In the C-terminus of the 5-HT7 receptor, we identified two YXXΦ motifs, LR residues, and a palmitoylated cysteine anchor as potential sites involved in receptor trafficking to lysosomes followed by receptor degradation. Mutating either of these sites inhibited clozapine- and olanzapine-mediated degradation of 5-HT7 receptors and also interfered with G protein activation. In addition, we tested whether receptor degradation was mediated by the GPCR-associated sorting protein-1 (GASP-1). We show that GASP-1 binds the 5-HT7 receptor and regulates the clozapine-mediated degradation. Mutations of the identified motifs and residues, located in or close to Helix-VIII of the 5-HT7 receptor, modified antipsychotic-stimulated binding of proteins (such as GASP-1), possibly by altering the flexibility of Helix-VIII, and also interfered with G protein activation. Taken together, our data demonstrate that binding of clozapine or olanzapine to the 5-HT7 receptor leads to antagonist-mediated lysosomal degradation by exposing key residues in the C-terminal tail that interact with GASP-1.

  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. Interaction of Pyridostigmine with the 5-HT(3) Receptor Antagonist Ondansetron in Guinea Pigs

    DTIC Science & Technology

    1993-05-13

    5 - HT3 RECEPTOR - ANTAGONIST .ONDANSETRON IN GUINEA PIGS BR. Capacio, CE. Byers...apart. REFERENCES 1. Fozard JR. 5 -HT; The Enigma Variations. =JE, 8, 501-506 (December 1987). 2. Watling KJ. 5 - HT3 Receptor Agonists and Antagonists . In... 5 -HT receptor subtype three antagonists (5HT 3 ) such as the compound ondansetron (OND) have been identified as useful in the treatment of

  10. Reductions in Brain 5-HT1B Receptor Availability in Primarily Cocaine-Dependent Humans

    PubMed Central

    Matuskey, David; Bhagwagar, Zubin; Planeta, Beata; Pittman, Brian; Gallezot, Jean-Dominique; Chen, Jason; Wanyiri, Jane; Najafzadeh, Soheila; Ropchan, Jim; Geha, Paul; Huang, Yiyun; Potenza, Marc N.; Neumeister, Alexander; Carson, Richard E.; Malison, Robert T.

    2014-01-01

    Background Preclinical evidence implicates the 5-HT1B receptor in cocaine’s effects. This study explores 5-HT1B in humans by examining receptor availability in vivo with primary cocaine-dependent (CD) subjects using positron emission tomography (PET). Methods Fourteen medically healthy CD subjects (mean age=41±6 yrs) were compared to 14 age-matched healthy control subjects (41±8 yrs) with no past or current history of cocaine or other illicit substance abuse. Participants received an MRI and then a PET scan with the highly selective 5HT1B tracer, [11C]P943, for purposes of quantifying regional binding potential (BPND). Voxel-based morphometry (VBM) and gray matter masking (GMM) were also employed to control for potential partial volume effects. Results [11C]P943 PET imaging data in nine candidate regions (amygdala, anterior cingulate cortex, caudate, frontal cortex, hypothalamus, pallidum, putamen, thalamus and ventral striatum) showed significant or nearly significant reductions of BPND in CD subjects in three regions, including the anterior cingulate (−16%; P<0.01), hypothalamus (−16%, P=0.03) and frontal cortex (−7%, P=0.08). VBM showed significant gray matter reductions in the frontal cortex of CD subjects. After GMM, statistically significant reductions in [11C]P943 BPND were either retained (anterior cingulate, −14%, p=0.01; hypothalamus, −20%, P<0.01) or achieved (frontal cortex, −14%, p<0.01). Whole brain voxel-wise parameter estimation confirmed these results. Secondary analyses were also significant in some regions for years of cocaine and daily tobacco use. Conclusions The reductions found in this study suggest that 5-HT1B receptors may contribute to the etiology and/or expression of cocaine dependence and potentially represent a target for medication development. PMID:24433854

  11. Synthesis and structure-activity relationship of novel conformationally restricted analogues of serotonin as 5-HT6 receptor ligands.

    PubMed

    Nirogi, Ramakrishna V S; Kambhampati, Ramasastri; Kothmirkar, Prabhakar; Konda, Jagadishbabu; Bandyala, Thrinath Reddy; Gudla, Parandhama; Arepalli, Sobhanadri; Gangadasari, Narasimhareddy P; Shinde, Anil K; Deshpande, Amol D; Dwarampudi, Adireddy; Chindhe, Anil K; Dubey, Pramod Kumar

    2012-06-01

    5-Hydroxytryptamine 6 receptors (5-HT(6)R) are being perceived as the possible target for treatment of cognitive disorders as well as obesity. The present article deals with the design, synthesis, in vitro binding and structure-activity relationship of a novel series of tetracyclic tryptamines with the rigidized N-arylsulphonyl, N-arylcarbonyl and N-benzyl substituents as 5-HT(6) receptor ligands. The chiral sulphonyl derivatives 15a and 17a showed high affinity at 5-HT(6)R with the K(i) of 23.4 and 20.5 nM, respectively. The lead compound from the series 15a has acceptable ADME properties, adequate brain penetration and is active in animal models of cognition like Novel Object Recognition Task (NORT) and water maze.

  12. Characterization of 5-HT receptors mediating constriction of porcine carotid arteriovenous anastomoses; involvement of 5-HT1B/1D and novel receptors

    PubMed Central

    De Vries, Peter; Villalón, Carlos M; Heiligers, Jan P C; Saxena, Pramod R

    1998-01-01

    It was previously shown that porcine cranial arteriovenous anastomoses (AVAs) constrict to 5-hydroxytryptamine (5-HT), ergotamine, dihydroergotamine, as well as sumatriptan and that sumatriptan acts exclusively via 5-HT1B/1D receptors. The present study was devoted to establish the contribution of 5-HT1B/1D receptors in the constriction of AVAs elicited by 5-HT (in presence of 0.5 mg kg−1 ketanserin), ergotamine and dihydroergotamine in anaesthetized pigs.Intracarotid infusion of 5-HT (2 μg kg−1 min−1) and intravenous doses of ergotamine (2.5–20 μg kg−1) and dihydroergotamine (3–100 μg kg−1) reduced AVA and increased nutrient blood flows and vascular conductances. The vasodilator response to 5-HT, observed mainly in the skin and ear, was much more prominent than that of the ergot alkaloids.Treatment with the 5-HT1B/1D receptor antagonist GR127935 (0.5 mg kg−1, i.v.) significantly attenuated both ergot-induced AVA constriction and arteriolar dilatation, whereas GR127935 only slightly affected the carotid vascular effects of 5-HT.The results suggest that 5-HT constricts carotid AVAs primarily via receptors, which seem to differ from those (5-HT1B/1D) stimulated by sumatriptan. The ergot alkaloids produce AVA constriction for a substantial part via 5-HT1B/1D receptors, but also stimulate unidentified receptors. Both these non-5-HT1B/1D receptors may be targets for the development of novel antimigraine drugs.The moderate vasodilator response to the ergot derivatives seems to be mediated, at least in part, by 5-HT1B/1D receptors, whereas the arteriolar dilatation caused by 5-HT may be mediated by other, possibly 5-HT7 receptors. PMID:9605562

  13. 5-HT1A and 5-HT1B receptors differentially modulate rate and timing of auditory responses in the mouse inferior colliculus

    PubMed Central

    Ramsey, Lissandra Castellan Baldan; Sinha, Shiva R.; Hurley, Laura M.

    2010-01-01

    Serotonin is a physiological signal that translates both internal and external information about behavioral context into changes in sensory processing through a diverse array of receptors. The details of this process, particularly how receptors interact to shape sensory encoding, are poorly understood. In the inferior colliculus, a midbrain auditory nucleus, serotonin (5-HT) 1A receptors have suppressive and 5-HT1B receptors have facilitatory effects on evoked responses of neurons. We explored how these two receptor classes interact by testing three hypotheses: that they 1) affect separate neuron populations, 2) affect different response properties, or 3) have different endogenous patterns of activation. The first two hypotheses were tested by iontophoretic application of 5-HT1A and 5-HT1B receptor agonists individually and together to neurons in vivo. 5-HT1A and 5-HT1B agonists affected overlapping populations of neurons. During co-application, 5-HT1A and 5-HT1B agonists influenced spike rate and frequency bandwidth additively, with each moderating the effect of the other. In contrast, although both agonists individually influenced latencies and interspike intervals, the 5-HT1A agonist dominated these measurements during co-application. The third hypothesis was tested by applying antagonists of the 5-HT1A and 5-HT1B receptors. Blocking 5-HT1B receptors was complementary to activation of the receptor, but blocking 5-HT1A receptors was not, suggesting the endogenous activation of additional receptor types. These results suggest that cooperative interactions between 5-HT1A and 5-HT1B receptors shape auditory encoding in the IC, and that the effects of neuromodulators within sensory systems may depend nonlinearly on the specific profile of receptors that are activated. PMID:20646059

  14. Serotonin (5-HT) inhibits Factor XIII-A-mediated plasma fibronectin matrix assembly and crosslinking in osteoblast cultures via direct competition with transamidation.

    PubMed

    Cui, Cui; Kaartinen, Mari T

    2015-03-01

    Serotonin (5-HT)--a monoamine with a variety of physiological functions--has recently emerged as a major regulator of bone mass. 5-HT is synthesized in the brain and the gut, and gut-derived 5-HT contributes to circulating 5-HT levels and is a negative modulator of bone mass and quality. 5-HT's negative effects on the skeleton are considered to be mediated via its receptors and transporter in osteoblasts and osteoclasts; however, 5-HT can also incorporate covalently into proteins via a transglutaminase-mediated serotonylation reaction, which in turn can alter protein function. Plasma fibronectin (pFN)--a major component of the bone extracellular matrix that regulates bone matrix quality in vivo--is a major transglutaminase substrate in bone and in osteoblast cultures. We have recently demonstrated that pFN assembly into osteoblast culture matrix requires a Factor XIII-A (FXIII-A) transglutaminase-mediated crosslinking step that regulates both quantity and quality of type I collagen matrix in vitro. In this study, we show that 5-HT interferes with pFN assembly into the extracellular matrix in osteoblast cultures, which in turn has major consequences on matrix assembly and mineralization. 5-HT treatment of MC3T3-E1 osteoblast cultures dramatically decreased both pFN fibrillogenesis as analyzed by immunofluorescence microscopy and pFN levels in DOC-soluble and DOC-insoluble matrix fractions. This was accompanied by an increase in pFN levels in the culture media. Analysis of the media showed covalent incorporation of 5-HT into pFN. Minor co-localization of pFN with 5-HT was also seen in extracellular fibrils. 5-HT also showed co-localization with FXIII-A on the cell surface and inhibited its transamidation activity directly. 5-HT treatment of osteoblast cultures resulted in a discontinuous pFN matrix and impaired type I collagen deposition, decreased alkaline phosphatase and lysyl oxidase activity, and delayed mineralization of the cultures. Addition of excess

  15. Effects of amyloid-β peptides on the serotoninergic 5-HT1A receptors in the rat hippocampus.

    PubMed

    Verdurand, Mathieu; Bérod, Anne; Le Bars, Didier; Zimmer, Luc

    2011-01-01

    A recent [(18)F]MPPF-positron emission tomography study has highlighted an overexpression of 5-HT(1A) receptors in the hippocampus of patients with mild cognitive impairment compared to a decrease in those with Alzheimer's disease (AD) [Truchot, L., Costes, S.N., Zimmer, L., Laurent, B., Le Bars, D., Thomas-Antérion, C., Croisile, B., Mercier, B., Hermier, M., Vighetto, A., Krolak-Salmon, P., 2007. Up-regulation of hippocampal serotonin metabolism in mild cognitive impairment. Neurology 69 (10), 1012-1017]. We used in vivo and in vitro neuroimaging to evaluate the longitudinal effects of injecting amyloid-β (Aβ) peptides (1-40) into the dorsal hippocampus of rats. In vivo microPET imaging showed no significant change in [(18)F]MPPF binding in the dorsal hippocampus over time, perhaps due to spatial resolution. However, in vitro autoradiography with [(18)F]MPPF (which is antagonist) displayed a transient increase in 5-HT(1A) receptor density 7 days after Aβ injection, whereas [(18)F]F15599 (a radiolabelled 5-HT(1A) agonist) binding was unchanged suggesting that the overexpressed 5-HT(1A) receptors were in a non-functional state. Complementary histology revealed a loss of glutamatergic neurons and an intense astroglial reaction at the injection site. Although a neurogenesis process cannot be excluded, we propose that Aβ injection leads to a transient astroglial overexpression of 5-HT(1A) receptors in compensation for the local neuronal loss. Exploration of the functional consequences of these serotoninergic modifications during the neurodegenerative process may have an impact on therapeutics targeting 5-HT(1A) receptors in AD.

  16. The 5-HT1A receptor in Major Depressive Disorder

    PubMed Central

    Kaufman, Joshua; DeLorenzo, Christine; Choudhury, Sunia; Parsey, Ramin V.

    2016-01-01

    Major Depressive Disorder (MDD) is a highly prevalent psychiatric diagnosis that is associated with a high degree of morbidity and mortality. This debilitating disorder is currently one of the leading causes of disability nationwide and is predicted to be the leading cause of disease burden by the year 2030. A large body of previous research has theorized that serotonergic dysfunction, specifically of the serotonin (5-HT) 1A receptor, plays a key role in the development of MDD. The purpose of this review is to describe the evolution of our current understanding of the serotonin 1A (5-HT1A) receptor and its role in the pathophysiology MDD through the discussion of animal, post-mortem, positron emission tomography (PET), pharmacologic and genetic studies. PMID:26851834

  17. The 5-HT1A receptor in Major Depressive Disorder.

    PubMed

    Kaufman, Joshua; DeLorenzo, Christine; Choudhury, Sunia; Parsey, Ramin V

    2016-03-01

    Major Depressive Disorder (MDD) is a highly prevalent psychiatric diagnosis that is associated with a high degree of morbidity and mortality. This debilitating disorder is currently one of the leading causes of disability nationwide and is predicted to be the leading cause of disease burden by the year 2030. A large body of previous research has theorized that serotonergic dysfunction, specifically of the serotonin (5-HT) 1A receptor, plays a key role in the development of MDD. The purpose of this review is to describe the evolution of our current understanding of the serotonin 1A (5-HT1A) receptor and its role in the pathophysiology MDD through the discussion of animal, post-mortem, positron emission tomography (PET), pharmacologic and genetic studies.

  18. Role of 5-HT2 receptors in diabetes: Swertiamarin seco-iridoid glycoside might be a possible 5-HT2 receptor modulator.

    PubMed

    Sonawane, Rakesh Deelip; Deore, Vijaykumar B; Patil, Savita D; Patil, Chandragouda R; Surana, Sanjay J; Goyal, Ramesh K

    2015-05-15

    In the present review, we are focusing on modulators of 5-HT2 receptors, swertiamarin and their role in diabetes. These drugs possess both central and peripheral actions in various animal models of depression, diabetes and obesity. Swertiamarin and 5-HT2 antagonist are reported antidepressant, hypolipidemic and beneficial in peripheral vasculopathy. In contrast to this, 5-HT2C selective agonist decreases hyperglycemia, hyperlipidemia and insulin secretogogue by action. Selective serotonin reuptake inhibitors (SSRIs) are known antidepressant having weight gain as an adverse effect. Swertiamarin has similar pharmacological actions as 5-HT2 antagonist and 5-HT2C selective agonist. This warrants that swertiamarin might modulate 5-HT2 receptors rather than affecting the uptake of serotonin. In the light of present investigation, the mechanism of these drugs can correlate the role of central and peripheral 5-HT2 receptors in diabetes.

  19. Synthesis and structure-activity relationships of new carbonyl guanidine derivatives as novel dual 5-HT2B and 5-HT7 receptor antagonists.

    PubMed

    Moritomo, Ayako; Yamada, Hiroyoshi; Watanabe, Toshihiro; Itahana, Hirotsune; Akuzawa, Shinobu; Okada, Minoru; Ohta, Mitsuaki

    2013-12-15

    To identify potent dual 5-HT2B and 5-HT7 receptor antagonists, we synthesized a series of novel carbonyl guanidine derivatives and examined their structure-activity relationships. Among these compounds, N-(9-hydroxy-9H-fluorene-2-carbonyl)guanidine (10) had a good in vitro profile, that is, potent affinity for human 5-HT2B and 5-HT7 receptor subtypes (Ki=1.8 nM and Ki=17.6 nM, respectively) and high selectivity over 5-HT2A, 5-HT2C, α1, D2 and M1 receptors. Compound 10 also showed a suppressing effect on 5-HT-induced dural protein extravasation in guinea pigs when orally administered.

  20. Psychological, neuroimaging, and biochemical studies on functional association between impulsive behavior and the 5-HT2A receptor gene polymorphism in humans.

    PubMed

    Nomura, Michio; Nomura, Yasuyuki

    2006-11-01

    It has been suggested that impulsive behavior is caused by dysfunctional serotonergic 5-HT neurotransmission in the central nervous system (CNS). Brain neuroimaging studies have shown that behavioral inhibition is linked to the activation of cortex sites such as the ventral frontal cortex. Positron emission tomography (PET) imaging with [(18)F]altanserin to characterize 5-HT(2A) receptor binding revealed a reduction in 5-HT(2A) binding in the ventral frontal cortex in women who had recovered from impulsive diseases. These clinical, neuroimaging, and pharmacological studies appear to support the hypothesis that functional alteration of neurotransmission due to genetic polymorphisms of the 5-HT receptors may be involved in impulsive behavior modulation. Following evaluation by a self-reporting measure, it was proposed that a polymorphism in the promoter of the 5-HT(2A) receptor gene is the underlying cause of impulsive behavior; however, this hypothesis is not convincing. We examined whether the polymorphism in the 5-HT(2A) receptor gene promoter is involved in impulsive aggression by evaluating a behavioral task (Go/No-go task) in normal volunteers. The polymorphism of the 5-HT(2A) receptor gene promoter in lymphocytes from 71 volunteers was analyzed by using PCR. Impulsivity was defined as the number of commission errors (responding when one should not) recorded during a Go/No-go task; a larger number of commission errors indicate greater difficulty in inhibiting impulsive behavior. The subjects of the A-1438A allele group for the 5-HT(2A) receptor gene made more commission errors under the punishment-reward (PR)condition in a Go/No-go task than those in the G-1438G group. In the present review, we discuss and suggest the possible involvement of the A-1438A polymorphism of the 5HT2A receptor gene promoter in impulsive behavior. This hypothesis was evaluated by using a behavioral task measure that could directly reveal impulsive behavioral traits in humans.

  1. Structure-activity relationships of a series of substituted benzamides: potent D2/5-HT2 antagonists and 5-HT1a agonists as neuroleptic agents.

    PubMed

    Norman, M H; Rigdon, G C; Hall, W R; Navas, F

    1996-03-01

    A series of substituted (4-(4-(1,2-benzisothiazol-3-yl)-1-piperazinyl)butyl)benzamide derivatives was prepared and evaluated as potential atypical antipsychotic agents. The target compounds were readily prepared from their benzoyl chloride, benzoic acid, or isatoic anhydride precursors, and they were evaluated in vitro for their ability to bind to dopamine D2, serotonin 5-HT2, and serotonin 5-HT1a receptors. To assess the potential antipsychotic activity of these compounds, we investigated their ability to inhibit the apomorphine-induced climbing response in mice. Selected compounds were evaluated further to determine their side-effect potentials. Structure-activity relationships of both mono- and polysubstituted benzamides are discussed herein. While several analogues had potent in vitro and in vivo activities indicative of potential atypical antipsychotic activity, anthranilamide 77 (1192U90) ddemonstrated a superior pharmacological profile. As a result of this investigation, 1192U90 (2-amino-N-(4-(4-(1,2-benzisothiazol-3-yl)-1-piperazinyl)butyl)ben zamide hydrochloride) was selected for further evaluation and is currently in phase I clinical trials as a potential atypical antipsychotic agent.

  2. Peripheral and spinal 5-HT receptors participate in cholestatic itch and antinociception induced by bile duct ligation in rats

    PubMed Central

    Tian, Bin; Wang, Xue-Long; Huang, Ya; Chen, Li-Hua; Cheng, Ruo-Xiao; Zhou, Feng-Ming; Guo, Ran; Li, Jun-Cheng; Liu, Tong

    2016-01-01

    Although 5-HT has been implicated in cholestatic itch and antinociception, two common phenomena in patients with cholestatic disease, the roles of 5-HT receptor subtypes are unclear. Herein, we investigated the roles of 5-HT receptors in itch and antinociception associated with cholestasis, which was induced by common bile duct ligation (BDL) in rats. 5-HT-induced enhanced scratching and antinociception to mechanical and heat stimuli were demonstrated in BDL rats. 5-HT level in the skin and spinal cord was significantly increased in BDL rats. Quantitative RT-PCR analysis showed 5-HT1B, 5-HT1D, 5-HT2A, 5-HT3A, 5-HT5B, 5-HT6, and 5-HT7 were up-regulated in peripheral nervous system and 5-HT1A, 5-HT1F, 5-HT2B, and 5-HT3A were down-regulated in the spinal cord of BDL rats. Intradermal 5-HT2, 5-HT3, and 5-HT7 receptor agonists induced scratching in BDL rats, whereas 5-HT3 agonist did not induce scratching in sham rats. 5-HT1A, 5-HT2, 5-HT3, and 5-HT7 agonists or antagonists suppressed itch in BDL rats. 5-HT1A agonist attenuated, but 5-HT1A antagonist enhanced antinociception in BDL rats. 5-HT2 and 5-HT3 agonists or antagonists attenuated antinociception in BDL rats. Our data suggested peripheral and central 5-HT system dynamically participated in itch and antinociception under cholestasis condition and targeting 5-HT receptors may be an effective treatment for cholestatic itch. PMID:27824106

  3. [5-HT3 receptor antagonist als analgetics in rheumatic diseases].

    PubMed

    Müller, W; Fiebich, B L; Stratz, T

    2006-10-01

    Various rheumatic diseases like fibromyalgia, systemic inflammatory rheumatic disorders and localized diseases, such as arthritides and activated arthroses, tendinopathies and periarthropathies, as well as trigger points can be improved considerably by treatment with the 5-HT3 receptor antagonist tropisetron. Particularly in the latter group of diseases, local injections have done surprisingly rapid analgesic action. This effect matches that of local anesthetics, but lasts considerably longer and is comparable to local injections of local anesthetics combined with corticosteroids. The action of the 5-HT3 receptor antagonists can be attributed to an antinociceptive effect that occurs at the same time as an antiphlogistic and probably also an immunosuppressive effect. Whereas an inhibited release of substance P from the nociceptors, and possibly some other neurokins as well, seems to be the most likely explanation for the antinociceptive action, the antiphlogistic effect is primarily due to an inhibited formation of various different phlogistic substances; in some conditions, like systemic inflammatory rheumatic diseases, for example, the 5-HT3 receptor antagonists may exert an immunosuppressive effect in addition to this.

  4. The serotonin 5-HT7 receptors: two decades of research.

    PubMed

    Gellynck, Evelien; Heyninck, Karen; Andressen, Kjetil W; Haegeman, Guy; Levy, Finn Olav; Vanhoenacker, Peter; Van Craenenbroeck, Kathleen

    2013-10-01

    Like most neurotransmitters, serotonin possesses a simple structure. However, the pharmacological consequences are more complex and diverse. Serotonin is involved in numerous functions in the human body including the control of appetite, sleep, memory and learning, temperature regulation, mood, behavior, cardiovascular function, muscle contraction, endocrine regulation, and depression. Low levels of serotonin may be associated with several disorders, namely increase in aggressive and angry behaviors, clinical depression, Parkinson's disease, obsessive-compulsive disorder, eating disorders, migraine, irritable bowel syndrome, tinnitus, and bipolar disease. These effects are mediated via different serotonin (5-HT) receptors. In this review, we will focus on the last discovered member of this serotonin receptor family, the 5-HT7 receptor. This receptor belongs to the G protein-coupled receptor superfamily and was cloned two decades ago. Later, different splice variants were described but no major functional differences have been described so far. All 5-HT7 receptor variants are coupled to Gαs proteins and stimulate cAMP formation. Recently, several interacting proteins have been reported, which can influence receptor signaling and trafficking.

  5. The effects of the 5-HT(6) receptor agonist EMD and the 5-HT(7) receptor agonist AS19 on memory formation.

    PubMed

    Meneses, A; Perez-Garcia, G; Liy-Salmeron, G; Flores-Galvez, D; Castillo, C; Castillo, E

    2008-12-16

    Growing evidence indicates that 5-hydrohytryptamine (5-HT) receptors mediate learning and memory. Particularly interesting are 5-HT(6) and 5-HT(7) receptors, which are localized in brain areas involved in memory formation. Interestingly, recently selective 5-HT(6) and 5-HT(7) receptor agonists and antagonists have become available. Previous evidence indicates that 5-HT(6) or 5-HT(7) receptors antagonists had no effects, improved memory formation and/or reversed amnesia. Herein, the effects of EMD (a 5-HT(6) receptor agonist) and AS19 (a 5-HT(7) receptor agonist) in the associative learning task of autoshaping were studied. Post-training systemic administration of EMD (1-10 mg/kg) or AS19 (1-10 mg/kg) were tested in short-term memory (STM) and long-term memory (LTM). Results showed that only EMD 5.0mg/kg impaired both STM and LTM. AS19 at 1-10 mg/kg significantly impaired STM but not LTM. In those groups used to test only LTM, EMD impaired it; while AS19 improved LTM. Moreover, in the interaction experiments, the STM EMD-impairment effect was partially reversed by the selective 5-HT(6) receptor antagonist SB-399885 (10 mg/kg). The STM AS19-impairment effect (5.0 mg/kg) was not altered by the selective 5-HT(1A) antagonist WAY 100635 (0.3 mg/kg) but reversed by the selective 5-HT(7) receptor antagonist SB-269970 (10.0 mg/kg). The AS19-SB-269970 combination impaired LTM. Taken together these data suggest that the stimulation of 5-HT(6) impaired both STM and LTM. 5-HT(7) receptors stimulation impaired STM but improved LTM. And these results are discussed in the context of their possible neural bases.

  6. The atypical 5-HT2 receptor mediating tachycardia in pithed rats: pharmacological correlation with the 5-HT2A receptor subtype

    PubMed Central

    Centurión, David; Ortiz, Mario I; Saxena, Pramod R; Villalón, Carlos M

    2002-01-01

    In pithed rats, 5-HT mediates tachycardia both directly (by 5-HT2 receptors) and indirectly (by a tyramine-like effect). The receptor mediating tachycardia directly has been classified as an ‘atypical' 5-HT2 receptor since it was ‘weakly' blocked by ketanserin. Moreover, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a 5-HT2 agonist, failed to mimic 5-HT-induced tachycardia. Since 5-HT2 receptors consist of 5-HT2A, 5-HT2B and 5-HT2C subtypes, this study investigated if these subtypes mediate the above response. In pithed rats, intraperitoneally (i.p.) pre-treated with reserpine (5 mg kg−1), intravenous (i.v.) administration of 5-HT, 5-methoxytryptamine (5-MeO-T), 1-(3-chlorophenyl) piperazine (mCPP) and 5-carboxamidotryptamine (5-CT) (10, 30, 100 and 300 μg kg−1 each), produced dose-dependent tachycardic responses. Interestingly, DOI (10 – 1000 μg kg−1, i.v.) induced only slight, dose-unrelated, tachycardic responses, whilst the 5-HT2C agonist, Ro 60-0175 (10 – 1000 μg kg−1, i.v.), produced a slight tachycardia only at 300 and 1000 μg kg−1. In contrast, sumatriptan and 1-(m-trifluoromethylphenyl)- piperazine (TFMPP) were inactive. The rank order of potency was: 5-HT⩾5-MeO-T> mCPP⩾5-CT⩾DOI>Ro 60-0175. The tachycardic responses to 5-HT, which remained unaffected after i.v. saline (0.3 and 1 ml kg−1) or propranolol (3 mg kg−1), were selectively blocked by the 5-HT2A antagonists ketanserin (30 and 100 μg kg−1) or spiperone (10 and 30 μg kg−1) as well as by the non-selective 5-HT2 antagonists, ritanserin (10 and 30 μg kg−1) or mesulergine (100 μg kg−1). Remarkably, these responses were unaffected by the antagonists rauwolscine (5-HT2B), SB204741 (5-HT2B/2C) or Ro 04-6790 (5-ht6) (300 and 1000 μg kg−1 each). These results suggest that the ‘atypical' 5-HT2 receptors mediating tachycardia in reserpinized pithed rats are pharmacologically similar to the 5-HT2A

  7. Bi-directional modulation of BNST neurons by 5-HT: Molecular expression and functional properties of excitatory 5-HT receptor subtypes

    PubMed Central

    Guo, Ji-Dong; Hammack, Sayamwong E.; Hazra, Rimi; Levita, Liat; Rainnie, Donald G.

    2009-01-01

    Activation of neurons in the anterolateral bed nucleus of the stria terminalis (BNSTALG) plays an important role in mediating the behavioral response to stressful and anxiogenic stimuli. Application of 5-HT elicits complex postsynaptic responses in BNSTALG neurons, which includes 1) membrane hyperpolarization (5-HTHyp), 2) hyperpolarization followed by depolarization (5-HTHyp-Dep), 3) depolarization (5-HTDep) or 4) no response (5-HTNR). We have shown that the inhibitory response is mediated by activation of postsynaptic 5-HT1A receptors. Here, we used a combination of in vitro whole-cell patch-clamp recording and single cell reverse transcriptase polymerase chain reaction (RT-PCR) to determine the pharmacological properties and molecular profile of 5-HT receptor subtypes mediating the excitatory response to 5-HT in BNSTALG neurons. We show that the depolarizing component of both the 5-HTHyp/Dep and the 5-HTDep response was mediated by activation of 5-HT2A, 5-HT2C and/or 5-HT7 receptors. Single cell RT-PCR data revealed that 5-HT7 receptors (46%) and 5-HT1A receptors (41%) are the most prevalent receptor subtypes expressed in BNSTALG neurons. Moreover, 5-HT receptor subtypes are differentially expressed in Type I – III BNSTALG neurons. Hence, 5-HT2C receptors are almost exclusively expressed by Type III neurons, whereas 5-HT7 receptors are expressed by Type I and II neurons, but not Type III neurons. Conversely, 5-HT2A receptors are found predominantly in Type II neurons. Finally, bi-directional modulation of individual neurons occurs only in Type I and II neurons. Significantly the distribution of 5-HT receptor subtypes in BNSTALG neurons predicted the observed expression pattern of 5-HT responses determined pharmacologically. Together, these results suggest that 5-HT can differentially modulate the excitability of Type I – III neurons, and further suggest that bi-directional modulation of BNSTALG neurons occurs primarily through an interplay between 5-HT1A and

  8. 5-HT manipulation and dietary choice: variable carbohydrate (Polycose) suppression demonstrated only under specific experimental conditions.

    PubMed

    Lawton, C L; Blundell, J E

    1993-01-01

    The effects of six 5-HT anorectic agents, d-fenfluramine (5-HT releaser and reuptake inhibitor), fluoxetine (5-HT reuptake inhibitor), mCPP (5-HT1B/5-HT1C receptor agonist), RU24969 (5-HT1A/5-HT1B receptor agonist), MK212 (5-HT1C receptor agonist) and DOI (5-HT2/5-HT1C receptor agonist), and two non-5-HT anorectic agents, salbutamol (beta 2-adrenergic agonist) and d-amphetamine (catecholaminergic agonist), were examined in an experimental procedure designed to disclose selective effects on carbohydrate consumption. In this procedure, a revised version of what we have termed "The Classic Sclafani Paradigm", animals are presented with powdered Polycose as an optional carbohydrate supplement to hydrated chow (nutritionally complete diet). All drugs produced significant reductions in total (hydrated chow plus powdered Polycose) intake. However, only the 5-HT drugs DOI and fluoxetine exerted significantly stronger anorectic effects on intake of powdered Polycose than on intake of hydrated chow. d-Fenfluramine also showed a tendency to selectively suppress Polycose intake but this effect marginally failed to reach significance. These results suggest that when experimental conditions are favourable, what appears to be selective carbohydrate (Polycose) suppression can be demonstrated with certain 5-HT drugs. They also suggest that a selective effect on carbohydrate intake is not the most prominent feeding response to 5-HT drugs.

  9. Effects of methysergide and 5-hydroxytryptamine on carotid blood flow distribution in pigs: further evidence for the presence of atypical 5-HT receptors.

    PubMed Central

    Saxena, P. R.; Verdouw, P. D.

    1984-01-01

    The effects of acute (50-350 micrograms kg-1, i.v.) and subacute (350 micrograms kg-1 orally per day for six days) administration of methysergide, and of intra-arterial infusions of 0.5 and 2.0 micrograms kg-1 min-1 5-hydroxytryptamine (5-HT) on the distribution of carotid blood flow into the capillary (nutrient) and arterio-venous anastomotic (AVA) fractions were studied in anaesthetized pigs. The acute, but not the subacute, administration of methysergide caused a moderate reduction of carotid blood flow. This reduction, noticed only in the AVA fraction, was due to a constriction of the arterio-venous anastomoses (AVAs). Both doses of 5-HT reduced total carotid blood flow but its nutrient fraction--particularly that distributed to the skin and ears--increased substantially. The AVA fraction was greatly diminished. After treatment with methysergide, 5-HT no longer reduced the total carotid blood flow, but increased it. Despite this reversal the constriction of AVAs by the amine was only slightly diminished. On the other hand, the vasodilatation of the nutrient channels was enhanced. The results of the interaction between methysergide and 5-HT provide further evidence for the presence of 'atypical' 5-HT receptors (probably corresponding to 5-HT1 binding sites) mediating AVA contraction and nutrient vasodilatation. The 5-HT2 receptors mediate vasoconstriction and are located in the large conducting arteries and possibly, in smaller numbers, in the AVAs and arterioles. PMID:6478112

  10. Anxiolytic-like effects observed in rats exposed to the elevated zero-maze following treatment with 5-HT2/5-HT3/5-HT4 ligands

    PubMed Central

    Bell, Rob; Duke, Aaron A.; Gilmore, Paula E.; Page, Deaglan; Bègue, Laurent

    2014-01-01

    The present study examined the effects of administering selective 5-HT antagonists and agonists to rats tested in the elevated zero-maze (EZM) model of anxiety. The EZM paradigm has advantages over the elevated plus-maze (EPM) paradigm with respect to measuring anxiety, yet has been utilized less frequently. Three experiments were conducted each with a diazepam control (0.25, 0.5 and 0.75 mg/kg). In the first experiment, we administered the 5-HT2C antagonist RS 102221 (0.5, 1.0, and 2.0 mg/kg) and 5-HT2C agonist MK-212 (0.25, 0.5 and 0.75 mg/kg); in the second experiment, we administered the 5-HT3 antagonist Y-25130 (0.1, 1.0 and 3.0 mg/kg) and 5-HT3 agonist SR 57227A (0.1, 1.0 and 3.0 mg/kg), and in the third experiment, we administered the 5-HT4 antagonist RS 39604 (0.01, 0.1, 1.0 mg/kg) and 5-HT4 agonist RS 67333 (0.01, 0.1 and 0.5 mg/kg). The administration of 5-HT2/3/4 subtype antagonists all generated behavioral profiles indicative of anxiolytic-like effects in the EZM, which was apparent from examination of both traditional and ethological measures. While little effect was observed from 5-HT2 and 5-HT3 agonists, the 5-HT4 agonist RS 67333 was found to produce a paradoxical anxiolytic-like effect similar to that produced by the 5-HT4 antagonist RS 39604. We conclude by discussing the implications of these findings. PMID:24457553

  11. Differences in agonist dissociation constant estimates for 5-HT at 5-HT2-receptors: a problem of acute desensitization?

    PubMed Central

    Leff, P.; Martin, G. R.

    1988-01-01

    1. The agonist dissociation constant for 5-hydroxytryptamine (5-HT) was estimated in the guinea-pig isolated trachea by the method of receptor inactivation. The value obtained (pKA = 6.45) was significantly lower than estimates previously obtained in the rabbit aorta and rat jugular vein, although all three tissues are supposed to contain the same 5-HT2 class of receptor. 2. The antagonist dissociation constant for alpha,alpha-dimethyltryptamine was also estimated in the guinea-pig trachea. The pKB value (5.43) was not significantly different from previous estimates in the rabbit aorta and rat jugular vein, consistent with receptor homogeneity between the three tissues. 3. The effect-time profiles corresponding to individual 5-HT applications were more transient in the guinea-pig trachea than in the rabbit aorta. This difference could be accounted for using a simple model of acute receptor desensitization (Leff, 1986), assuming that the conversion of active agonist-receptor complexes into inactive ones was faster in the guinea-pig trachea than in the rabbit aorta. 4. Computer simulation of the desensitization model showed that the discrepancy of pKA estimates for 5-HT between the rabbit aorta and guinea-pig trachea could also be explained using the same rate constant difference that accounted for the difference in effect-time profiles. This analysis indicated that the estimate made in the trachea was erroneously low, whereas that made in the aorta was concluded to be correct. 5. The apparent association between transience of response and pKA estimates is discussed with particular attention to the reliability of agonist affinity estimates in receptor classification. PMID:3228675

  12. Signalling pathways activated by 5-HT(1B)/5-HT(1D) receptors in native smooth muscle and primary cultures of rabbit renal artery smooth muscle cells.

    PubMed

    Hinton, J M; Hill, P; Jeremy, J; Garland, C

    2000-01-01

    The potential of primary cultures of rabbit renal artery vascular smooth muscle cells (VSMCs) was assessed as a means to investigate the signalling pathways linked to 5-hydroxytryptamine (5-HT) 5-HT(1B)/5-HT(1D) receptors in native arteries. In renal artery segments denuded of endothelium, incubated with ketanserin and prazosin (each 1 microM), and prestimulated with 20 mM K(+) Krebs buffer, 5-HT and CP 93,129, a 5-HT(1B) receptor agonist, evoked concentration-dependent contractions. GR 127935, a 5-HT(1B)/5-HT(1D) receptor antagonist, significantly antagonised 5-HT-evoked contractions at nanomolar concentrations. Reverse transcription polymerase chain reaction (RT-PCR) of mRNA from smooth muscle cells from the isolated renal artery and from primary cultures of VSMCs from the same artery expressed mRNA transcripts for the 5-HT(1B) receptor and the 5-HT(1D) receptor in both preparations. The sequence of the PCR fragments corresponded to the known sequence for these receptors. Application of 5-HT evoked a concentration-dependent, pertussis toxin (PTx)-sensitive reduction in cyclic AMP in both cultured cells and intact artery (cyclic AMP concentration reduced by 65.53 +/- 3.33 and 52.65 +/- 5.34% from basal with 10 microM 5-HT, respectively). The effect of 10 microM 5-HT on cAMP was increased in the presence of 20 mM K(+) (reduced by 82.50 +/- 2.50 and 87.54 +/- 3.97%, respectively). In intact arteries, contraction through 5-HT(1B)/5-HT(1D) receptors was significantly attenuated by inhibitors of phosphatidylinositol 3-kinase (wortmannin) and activated mitogen-activated protein kinase (MAPK), MEK (U0126). In the cultured VSMCs, activated MAPK was identified by immunocytochemistry and immunoblotting after stimulation with 5-HT, but only if 20 mM K(+) was present at the onset of stimulation. These data provide the first direct evidence that 5-HT(1B)/5-HT(1B) receptors are linked to the activation of MAPK and indicate that primary cultures of renal VSMCs could provide a

  13. 5-HT is a potent relaxant in rat superior mesenteric veins.

    PubMed

    Watts, Stephanie W; Darios, Emma S; Seitz, Bridget M; Thompson, Janice M

    2015-02-01

    Serotonin (5-HT, 5-hydroxytryptamine) reduces blood pressure of the conscious rat when administered chronically (1 week). 5-HT does not directly relax isolated arteries, and microsphere experiments in 5-HT-infused rats suggested that 5-HT increased flow to the splanchnic bed. We hypothesized that 5-HT increased splanchnic flow because of direct venous relaxation; our focus was thus on the superior mesenteric vein (SMV) as an important vein in splanchnic circulation. Real-time RT-PCR, immunohistochemistry and Western analyses supported the predominant expression of the 5-HT2B and 5-HT7 receptor in the SMV. The SMV was mounted in tissue baths for measurement of isometric contraction. 5-HT caused a concentration-dependent relaxation of the endothelin-1 (ET-1)-contracted vein. The threshold of 5-HT-induced venous relaxation was significantly lower than for 5-HT-induced venous contraction (∼2 vs. 700 nmol/L, respectively). A series of serotonergic agonists established in their use of receptor characterization was tested, and the following rank order of potency found for agonist-induced relaxation (receptor selectivity): 5-CT (5-HT1/5-HT7)>5-HT = LP-44 (5-HT7)>PNU109291 (5-HT1D) = BW723C86 (5-HT2B). 8-OH-DPAT (5-HT1A/7), CP93129 (5-HT1B), mCPBG (5-HT3/4), AS19 (5-HT7) and TCB-2 (5-HT2A) did not relax the isolated vein. Consistent with these findings, two different 5-HT7 receptor antagonists SB 269970 and LY215840 but not the 5-HT2B receptor antagonist LY272015 nor the nitric oxide synthase inhibitor LNNA abolished 5-CT-induced relaxation of the isolated SMV. 5-CT (1 μg kg(-1) min(-1), sc) also reduced blood pressure over 7 days. These findings suggest that 5-HT directly relaxes the SMV primarily through activation of the 5-HT7 receptor.

  14. GR-127935-sensitive mechanism mediating hypotension in anesthetized rats: are 5-HT5B receptors involved?

    PubMed

    Sánchez-Maldonado, Carolina; López-Sánchez, Pedro; Anguiano-Robledo, Liliana; Leopoldo, Marcello; Lacivita, Enza; Terrón, José A

    2015-04-01

    The 5-HT1B/1D receptor antagonist, GR-127935, inhibits hypotensive responses produced by the 5-HT1A, 5-HT1B/1D and 5-HT7 receptor agonist, and 5-HT5A/5B receptor ligand, 5-carboxamidotryptamine (5-CT), in rats. This work further characterized the above mechanism using more selective 5-HT1B and 5-HT1D receptor antagonists. Also, expression of 5-HT5A and 5-HT5B receptor mRNAs in blood vessels was searched by reverse transcription polymerase chain reaction. Decreases in diastolic blood pressure induced by 5-CT (0.001-10 μg/kg, intravenously) were analyzed in anesthetized rats that had received intravenous vehicle (1 mL/kg), SB-224289 (5-HT1B antagonist; 0.3 and 1.0 mg/kg), BRL15572 (5-HT1D antagonist; 0.3 and 1.0 mg/kg), SB-224289 + BRL15572 (0.3 mg/kg, each), or SB-224289 + BRL15572 (0.3 mg/kg, each) + GR-127935 (1 mg/kg). Because only the latter treatment inhibited 5-CT-induced hypotension, suggestive of a mechanism unrelated to 5-HT1B/1D receptors, the effects of antagonists/ligands at 5-HT5A (SB-699551, 1 mg/kg), 5-HT6 (SB-399885, 1 mg/kg), and 5-HT1B/1D/5A/5B/7 receptors (ergotamine, 0.1 mg/kg) on 5-CT-induced hypotension were tested. Interestingly, only ergotamine blocked 5-CT-induced responses; this effect closely paralleled that of SB-224289 + BRL-15572 + GR-127935. Neither did ergotamine nor GR-127935 inhibit hypotensive responses induced by the 5-HT7 receptor agonist, LP-44. Faint but clear bands corresponding to 5-HT5A and 5-HT5B receptor mRNAs in aorta and mesenteric arteries were detected. Results suggest that the GR-127935-sensitive mechanism mediating hypotension in rats is unrelated to 5-HT1B, 5-HT1D, 5-HT5A, 5-HT6, and 5-HT7 receptors. This mechanism, however, resembles putative 5-HT5B receptors.

  15. 5-HT is a potent relaxant in rat superior mesenteric veins

    PubMed Central

    Watts, Stephanie W; Darios, Emma S; Seitz, Bridget M; Thompson, Janice M

    2015-01-01

    Serotonin (5-HT, 5-hydroxytryptamine) reduces blood pressure of the conscious rat when administered chronically (1 week). 5-HT does not directly relax isolated arteries, and microsphere experiments in 5-HT-infused rats suggested that 5-HT increased flow to the splanchnic bed. We hypothesized that 5-HT increased splanchnic flow because of direct venous relaxation; our focus was thus on the superior mesenteric vein (SMV) as an important vein in splanchnic circulation. Real-time RT-PCR, immunohistochemistry and Western analyses supported the predominant expression of the 5-HT2B and 5-HT7 receptor in the SMV. The SMV was mounted in tissue baths for measurement of isometric contraction. 5-HT caused a concentration-dependent relaxation of the endothelin-1 (ET-1)-contracted vein. The threshold of 5-HT-induced venous relaxation was significantly lower than for 5-HT-induced venous contraction (∼2 vs. 700 nmol/L, respectively). A series of serotonergic agonists established in their use of receptor characterization was tested, and the following rank order of potency found for agonist-induced relaxation (receptor selectivity): 5-CT (5-HT1/5-HT7)>5-HT = LP-44 (5-HT7)>PNU109291 (5-HT1D) = BW723C86 (5-HT2B). 8-OH-DPAT (5-HT1A/7), CP93129 (5-HT1B), mCPBG (5-HT3/4), AS19 (5-HT7) and TCB-2 (5-HT2A) did not relax the isolated vein. Consistent with these findings, two different 5-HT7 receptor antagonists SB 269970 and LY215840 but not the 5-HT2B receptor antagonist LY272015 nor the nitric oxide synthase inhibitor LNNA abolished 5-CT-induced relaxation of the isolated SMV. 5-CT (1 μg kg−1 min−1, sc) also reduced blood pressure over 7 days. These findings suggest that 5-HT directly relaxes the SMV primarily through activation of the 5-HT7 receptor. PMID:25692021

  16. Evidence for the existence of FGFR1-5-HT1A heteroreceptor complexes in the midbrain raphe 5-HT system.

    PubMed

    Borroto-Escuela, Dasiel O; Narvaez, Manuel; Pérez-Alea, Mileidys; Tarakanov, Alexander O; Jiménez-Beristain, Antonio; Mudó, Giuseppa; Agnati, Luigi F; Ciruela, Francisco; Belluardo, Natale; Fuxe, Kjell

    2015-01-02

    The ascending midbrain 5-HT neurons known to contain 5-HT1A autoreceptors may be dysregulated in depression due to a reduced trophic support. With in situ proximity ligation assay (PLA) and supported by co-location of the FGFR1 and 5-HT1A immunoreactivities in midbrain raphe 5-HT cells, evidence for the existence of FGFR1-5-HT1A heteroreceptor complexes were obtained in the dorsal and median raphe nuclei of the Sprague-Dawley rat. Their existence in the rat medullary raphe RN33B cell cultures was also established. After combined FGF-2 and 8-OH-DPAT treatment, a marked and significant increase in PLA positive clusters was found in the RN33B cells. Similar results were reached upon coactivation by agonists in HEK293T cells using the Fluorescent Resonance Energy Transfer (FRET) technique resulting in increased FRETmax and reduced FRET50 values. The heteroreceptor complex formation was dependent on TMV of the 5-HT1A receptor since it was blocked by incubation with TMV but not with TMII. Taken together, the 5-HT1A autoreceptors by being recruited into a FGFR1-5-HT1A heteroreceptor complex in the midbrain raphe 5-HT nerve cells may develop a novel function, namely a trophic role in many midbrain 5-HT neuron systems originating from the dorsal and medianus raphe nuclei.

  17. (3H)WB4101 labels the 5-HT1A serotonin receptor subtype in rat brain. Guanine nucleotide and divalent cation sensitivity

    SciTech Connect

    Norman, A.B.; Battaglia, G.; Creese, I.

    1985-12-01

    In the presence of a 30 nM prazosin mask, (/sup 3/H)-2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1,4-benzodioxane ((/sup 3/H)WB4101) can selectively label 5-HT1 serotonin receptors. Serotonin exhibits high affinity (Ki = 2.5 nM) and monophasic competition for (/sup 3/H) WB4101 binding in cerebral cortex. We have found a significant correlation (r = 0.96) between the affinities of a number of serotonergic and nonserotonergic compounds at (/sup 3/H)WB4101-binding sites in the presence of 30 nM prazosin and (/sup 3/H) lysergic acid diethylamide ((/sup 3/H)LSD)-labeled 5-HT1 serotonin receptors in homogenates of rat cerebral cortex. Despite similar pharmacological profiles, distribution studies indicate that, in the presence of 5 mM MgSO4, the Bmax of (/sup 3/H)WB4101 is significantly lower than the Bmax of (/sup 3/H)LSD in various brain regions. WB4101 competition for (/sup 3/H) LSD-labeled 5-HT1 receptors fits best to a computer-derived model assuming two binding sites, with the KH for WB4101 being similar to the KD of (/sup 3/H)WB4101 binding derived from saturation experiments. This suggests that (/sup 3/H)WB4101 labels only one of the subtypes of the 5-HT1 serotonin receptors labeled by (/sup 3/H)LSD. The selective 5-HT1A serotonin receptor antagonist, spiperone, and the selective 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino) tetraline, exhibit high affinity and monophasic competition for (/sup 3/H)WB4101 but compete for multiple (/sup 3/H)LSD 5-HT1 binding sites. These data indicate that (/sup 3/H)WB4101 selectively labels the 5-HT1A serotonin receptor, whereas (/sup 3/H) LSD appears to label both the 5-HT1A and the 5-HT1B serotonin receptor subtypes. The divalent cations, Mn2+, Mg2+, and Ca2+ were found to markedly increase the affinity and Bmax of (/sup 3/H)WB4101 binding in cerebral cortex. Conversely, the guanine nucleotides guanylylimidodiphosphate and GTP, but not the adenosine nucleotide ATP, markedly reduce the Bmax of (/sup 3/H)WB4101 binding.

  18. Potential antidepressant properties of SR 57746A, a novel compound with selectivity and high affinity for 5-HT1A receptors.

    PubMed

    Cervo, L; Bendotti, C; Tarizzo, G; Cagnotto, A; Skorupska, M; Mennini, T; Samanin, R

    1994-02-21

    SR 57746A, 4-(3-trifluoromethylphenyl)-N-[2-(naphth-2-yl)ethyl]-1,2,3,6- tetrahydropyridine HCl, was studied for its specific 5-HT1A receptor agonist action and antidepressant-like effects in the rat. The compound showed a high affinity for 5-HT1A specific binding sites in the rat hippocampus (IC50 3 nM), moderate affinity (10(-7)-10(-6) M) for dopamine D2 receptor, 5-HT uptake, 5-HT2 and alpha 1-adrenoceptor binding sites and practically no effect on binding sites of monoamine, GABAA, benzodiazepine and histamine receptors. It inhibited forskolin-stimulated adenylate cyclase activity in rat hippocampal membranes at concentrations of 10(-6) and 10(-5) M. The effect of 10(-6) M SR 57746A on forskolin-stimulated adenylate cyclase activity was completely antagonized by 10(-6) M (-)-propranolol. Administered per os as a three-dose course to rats, SR 57746A significantly increased struggling in the forced swimming test at doses from 0.3 to 3 mg/kg. Single doses had no such effect. The effect of a three-dose course with 1 mg/kg SR 57746A on rats' struggling was antagonized by pretreatment with 5 mg/kg i.p. metergoline, a non-selective 5-HT receptor antagonist, and by 20 mg/kg i.p. (-)-propranolol, an antagonist at 5-HT1 receptors. Three oral doses of 100 mg/kg parachlorophenylalanine, an inhibitor of 5-HT synthesis, and 100 mg/kg i.p. (+/-)-sulpiride, an antagonist at dopamine D2 receptors, also antagonized the effect of SR 57746A in the forced swimming test. The results show that SR 57746A has selectivity and high affinity for 5-HT1A receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Autoradiographic distribution of 5-HT7 receptors in the human brain using [3H]mesulergine: comparison to other mammalian species

    PubMed Central

    Martín-Cora, Francisco J; Pazos, Angel

    2003-01-01

    The main aim of this investigation was to delineate the distribution of the 5-HT7 receptor in human brain. Autoradiographic studies in guinea-pig and rat brain were also carried out in order to revisit and compare the anatomical distribution of 5-HT7 receptors in different mammalian species.Binding studies were performed in rat frontal cortex membranes using 10 nM [3H]mesulergine in the presence of raclopride (10 μM) and DOI (0.8 μM). Under these conditions, a binding site with pharmacological characteristics consistent with those of the 5-HT7 receptors was identified (rank order of binding affinity values: 5-CT>5-HT>5-MeOT>mesulergine ≈methiothepin>8-OH-DPAT=spiperone ≈(+)-butaclamol≫imipramine ≈(±)-pindolol≫ondansetron ≈clonidine ≈prazosin).The autoradiographic studies revealed that the anatomical distribution of 5-HT7 receptors throughout the human brain was heterogenous. High densities were found over the caudate and putamen nuclei, the pyramidal layer of the CA2 field of the hippocampus, the centromedial thalamic nucleus, and the dorsal raphe nucleus. The inner layer of the frontal cortex, the dentate gyrus of the hippocampus, the subthalamic nucleus and superior colliculus, among others, presented intermediate concentrations of 5-HT7 receptors. A similar brain anatomical distribution of 5-HT7 receptors was observed in all three mammalian species studied.By using [3H]mesulergine, we have mapped for the first time the anatomical distribution of 5-HT7 receptors in the human brain, overcoming the limitations previously found in radiometric studies with other radioligands, and also revisiting the distribution in guinea-pig and rat brain. PMID:14656806

  20. CREB-mediated synaptogenesis and neurogenesis is crucial for the role of 5-HT1a receptors in modulating anxiety behaviors

    PubMed Central

    Zhang, Jing; Cai, Cheng-Yun; Wu, Hai-Yin; Zhu, Li-Juan; Luo, Chun-Xia; Zhu, Dong-Ya

    2016-01-01

    Serotonin 1a-receptor (5-HT1aR) has been specifically implicated in the pathogenesis of anxiety. However, the mechanism underlying the role of 5-HT1aR in anxiety remains poorly understood. Here we show in mice that the transcription factor cAMP response element binding protein (CREB) in the hippocampus functions as an effector of 5-HT1aR in modulating anxiety-related behaviors. We generated recombinant lentivirus LV-CREB133-GFP expressing a dominant negative CREB which could not be phosphorylated at Ser133 to specifically reduce CREB activity, and LV-VP16-CREB-GFP expressing a constitutively active fusion protein VP16-CREB which could be phosphorylated by itself to specifically enhance CREB activity. LV-CREB133-GFP neutralized 5-HT1aR agonist-induced up-regulation of synapse density, spine density, dendrite complexity, neurogenesis, and the expression of synapsin and spinophilin, two well-characterized synaptic proteins, and abolished the anxiolytic effect of 5-HT1aR agonist; whereas LV-VP16-CREB-GFP rescued the 5-HT1aR antagonist-induced down-regulation of synapse density, spine density, dendrite complexity, neurogenesis and synapsin and spinophilin expression, and reversed the anxiogenic effect of 5-HT1aR antagonist. The deletion of neurogenesis by irradiation or the diminution of synaptogenesis by knockdown of synapsin expression abolished the anxiolytic effects of both CREB and 5-HT1aR activation. These findings suggest that CREB-mediated hippoacampus structural plasticity is crucial for the role of 5-HT1aR in modulating anxiety-related behaviors. PMID:27404655

  1. 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

  2. Mechanisms intrinsic to 5-HT2B receptor-induced potentiation of NMDA receptor responses in frog motoneurones.

    PubMed

    Holohean, Alice M; Hackman, John C

    2004-10-01

    In the presence of NMDA receptor open-channel blockers [Mg(2+); (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801); 1-amino-3,5-dimethyladamantane (memantine)] and TTX, high concentrations (30-100 microm) of either 5-hydroxytryptamine (5-HT) or alpha-methyl-5-hydroxytryptamine (alpha-Me-5-HT) significantly potentiated NMDA-induced depolarizations of frog spinal cord motoneurones. Potentiation was blocked by LY-53,857 (10-30 microm), SB 206553 (10 microm), and SB 204741 (30 microm), but not by spiroxatrine (10 microm), WAY 100,635 (1-30 microm), ketanserin (10 microm), RS 102221 (10 microm), or RS 39604 (10-20 microm). Therefore, alpha-Me-5-HT's facilitatory effects appear to involve 5-HT(2B) receptors. These effects were G-protein dependent as they were prevented by prior treatment with guanylyl-5'-imidodiphosphate (GMP-PNP, 100 microm) and H-Arg-Pro-Lys-Pro-Gln-Gln-D-Trp-Phe-D-Trp-D-Trp-Met-NH(2) (GP antagonist 2A, 3-6 microm), but not by pertussis toxin (PTX, 3-6 ng ml(-1), 48 h preincubation). This potentiation was not reduced by protein kinase C inhibition with staurosporine (2.0 microm), U73122 (10 microm) or N-(2-aminoethyl)-5-isoquinolinesulfonamide HCl (H9) (77 microm) or by intracellular Ca(2+) depletion with thapsigargin (0.1 microm) (which inhibits Ca(2+)/ATPase). Exposure of the spinal cord to the L-type Ca(2+) channel blockers nifedipine (10 microm), KN-62 (5 microm) or gallopamil (100 microm) eliminated alpha-Me-5-HT's effects. The calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphtalenesulfonamide (W7) (100 microm) diminished the potentiation. However, the calcium/calmodulin-dependent protein kinase II (CaM Kinase II) blocker KN-93 (10 microm) did not block the 5-HT enhancement of the NMDA responses. In summary, activation of 5-HT(2B) receptors by alpha-Me-5-HT facilitates NMDA-depolarizations of frog motoneurones via a G-protein, a rise in [Ca(2+)](i) from the entry of extracellular Ca(2+) through L-type Ca(2

  3. F 11440, a potent, selective, high efficacy 5-HT1A receptor agonist with marked anxiolytic and antidepressant potential.

    PubMed

    Koek, W; Patoiseau, J F; Assié, M B; Cosi, C; Kleven, M S; Dupont-Passelaigue, E; Carilla-Durand, E; Palmier, C; Valentin, J P; John, G; Pauwels, P J; Tarayre, J P; Colpaert, F C

    1998-10-01

    F 11440 (4-methyl-2-[4-(4-(pyrimidin-2-yl)-piperazino)-butyl]-2H, 4H-1,2,4-triazin-3,5-dione) was the outcome of a research effort guided by the hypothesis that the magnitude of the intrinsic activity of agonists at 5-HT1A receptors determines the magnitude of their antidepressant and anxiolytic-like effects. The affinity of F 11440 for 5-HT1A binding sites (pKi, 8.33) was higher than that of buspirone (pKi, 7.50), and somewhat lower than that of flesinoxan (pKi, 8.91). In vivo, F 11440 was 4- to 20-fold more potent than flesinoxan, and 30- to 60-fold more potent than buspirone, in exerting 5-HT1A agonist activity at pre- and postsynaptic receptors in rats (measured by, for example, its ability to decrease hippocampal extracellular serotonin (5-HT) levels and to increase plasma corticosterone levels, respectively). F 11440 did not have detectable antidopaminergic activity (unlike buspirone, which inhibited all of the directly observable behavioral effects of methylphenidate in rats), showed no evidence of antihistaminergic activity (unlike flesinoxan, which protected against the effects of a histamine aerosol in guinea pigs), and had a 70-fold separation between its 5-HT1A agonist and alpha-1 adrenergic antagonist properties (measured as the ability to inhibit the methoxamineinduced increase in blood pressure in rats), unlike flesinoxan, which showed a <3-fold separation. In HeLa cells expressing human 5-HT1A receptors, F 11440 decreased the forskolin-induced increase in AMP, and, based on its maximal effect, was found to have an intrinsic activity of 1.0 relative to that of 5-HT, which was significantly higher than that of buspirone (0.49), ipsapirone (0.46) and flesinoxan (0.93). Consistent with the aforementioned hypothesis, F 11440 produced anxiolytic- and antidepressant-like effects in animal models (i.e., increased punished responding in a pigeon conflict procedure and decreased immobility in a rat forced swimming test, respectively) that were more

  4. Impaired effect of activation of rat hippocampal 5-HT7 receptors, induced by treatment with the 5-HT7 receptor antagonist SB 269970.

    PubMed

    Kusek, M; Sowa, J; Tokarski, K; Hess, G

    2015-04-01

    Effects of the 5-HT(7) receptor antagonist SB 269970, administered for 14 days (1.25 mg/kg), were studied in ex vivo slices of rat hippocampus. To activate the 5-HT(7) receptor, 5-carboxamidotryptamine (5-CT, 200 nM) was applied in the presence of WAY 100635 (2 μM), a 5-HT(1A) receptor antagonist. In contrast to control preparations, no 5-HT(7) receptor-mediated increase in excitability nor depolarization and an increase in the input resistance of CA1 and CA3 pyramidal neurons were present in slices prepared from rats treated with SB 269970. The treatment also abolished the stimulatory effect of 5-HT(7) receptor activation on spontaneous excitatory postsynaptic currents recorded from CA1 stratum radiatum/lacunosum-moleculare interneurons. These data demonstrate that repeated administration of SB 269970 impairs the reactivity of the CA1 hippocampal neuronal network to 5-HT(7) receptor activation.

  5. Rational Drug Design Leading to the Identification of a Potent 5-HT(2C) Agonist Lacking 5-HT(2B) Activity.

    PubMed

    Chen, Gang; Cho, Sung Jin; Huang, Xi-Ping; Jensen, Niels H; Svennebring, Andreas; Sassano, Maria F; Roth, Bryan L; Kozikowski, Alan P

    2011-12-08

    The 5-HT(2C) receptor is an attractive drug target in the quest for new therapeutics to treat a variety of human disorders. We have previously undertaken a structural optimization campaign that has led to some potent and moderately selective 5-HT(2C) receptor agonists. After expanding our structure-function library, we were able to combine our datasets so as to allow the design of compounds of improved selectivity and potency. We disclose herein the structural optimization of our previously reported 5-HT(2B)/5-HT(2C) agonists, which has led to the identification of a highly selective 5-HT(2C) agonist, (+)-trans-[2-(2-cyclopropylmethoxyphenyl)cyclopropyl]methylamine hydrochloride, with an EC(50) of 55 nM and no detectable agonism at the 5-HT(2B) receptor.

  6. A Pharmacological Analysis of an Associative Learning Task: 5-HT1 to 5-HT7 Receptor Subtypes Function on a Pavlovian/Instrumental Autoshaped Memory

    PubMed Central

    Meneses, Alfredo

    2003-01-01

    Recent studies using both invertebrates and mammals have revealed that endogenous serotonin (5-hydroxytryptamine [5-HT]) modulates plasticity processes, including learning and memory. However, little is currently known about the mechanisms, loci, or time window of the actions of 5-HT. The aim of this review is to discuss some recent results on the effects of systemic administration of selective agonists and antagonists of 5-HT on associative learning in a Pavlovian/instrumental autoshaping (P/I-A) task in rats. The results indicate that pharmacological manipulation of 5-HT1-7 receptors or 5-HT reuptake sites might modulate memory consolidation, which is consistent with the emerging notion that 5-HT plays a key role in memory formation. PMID:14557609

  7. A pharmacological analysis of an associative learning task: 5-HT(1) to 5-HT(7) receptor subtypes function on a pavlovian/instrumental autoshaped memory.

    PubMed

    Meneses, Alfredo

    2003-01-01

    Recent studies using both invertebrates and mammals have revealed that endogenous serotonin (5-hydroxytryptamine [5-HT]) modulates plasticity processes, including learning and memory. However, little is currently known about the mechanisms, loci, or time window of the actions of 5-HT. The aim of this review is to discuss some recent results on the effects of systemic administration of selective agonists and antagonists of 5-HT on associative learning in a Pavlovian/instrumental autoshaping (P/I-A) task in rats. The results indicate that pharmacological manipulation of 5-HT1-7 receptors or 5-HT reuptake sites might modulate memory consolidation, which is consistent with the emerging notion that 5-HT plays a key role in memory formation.

  8. We Need 2C but Not 2B: Developing Serotonin 2C (5-HT2C) Receptor Agonists for the Treatment of CNS Disorders.

    PubMed

    Cheng, Jianjun; Kozikowski, Alan P

    2015-12-01

    The serotonin 2C (5-HT2C ) receptor has been identified as a potential drug target for the treatment of a variety of central nervous system (CNS) disorders, such as obesity, substance abuse, and schizophrenia. In this Viewpoint article, recent progress in developing selective 5-HT2C agonists for use in treating these disorders is summarized, including the work of our group. Challenges in this field and the possible future directions are described. Homology modeling as a method to predict the binding modes of 5-HT2C ligands to the receptor is also discussed. Compared to known ligands, the improved pharmacological profiles of the 2-phenylcyclopropylmethylamine-based 5-HT2C agonists make them preferred candidates for further studies.

  9. We Need 2C but Not 2B: Developing Serotonin 2C (5-HT2C) Receptor Agonists for the Treatment of CNS Disorders

    PubMed Central

    Cheng, Jianjun; Kozikowski, Alan P.

    2016-01-01

    The serotonin 2C (5-HT2C) receptor has been identified as a potential drug target for the treatment of a variety of central nervous system (CNS) disorders, such as obesity, substance abuse, and schizophrenia. In this Viewpoint article, recent progress in developing selective 5-HT2C agonists for use in treating these disorders is summarized, including the work of our group. Challenges in this field and the possible future directions are described. Homology modeling as a method to predict the binding modes of 5-HT2C ligands to the receptor is also discussed. Compared to known ligands, the improved pharmacological profiles of the 2-phenylcyclopropylmethylamine-based 5-HT2C agonists make them preferred candidates for further studies. PMID:26507582

  10. 5-HT6 receptor agonism facilitates emotional learning

    PubMed Central

    Pereira, Marcela; Martynhak, Bruno J.; Andreatini, Roberto; Svenningsson, Per

    2015-01-01

    Serotonin (5-HT) and its receptors play crucial roles in various aspects of mood and cognitive functions. However, the role of specific 5-HT receptors in these processes remains to be better understood. Here, we examined the effects of the selective and potent 5-HT6 agonist (WAY208466) on mood, anxiety and emotional learning in mice. Male C57Bl/6J mice were therefore tested in the forced swim test (FST), elevated plus-maze (EPM), and passive avoidance tests (PA), respectively. In a dose-response experiment, mice were treated intraperitoneally with WAY208466 at 3, 9, or 27 mg/kg and examined in an open field arena open field test (OFT) followed by the FST. 9 mg/kg of WAY208466 reduced immobility in the FST, without impairing the locomotion. Thus, the dose of 9 mg/kg was subsequently used for tests of anxiety and emotional learning. There was no significant effect of WAY208466 in the EPM. In the PA, mice were trained 30 min before the treatment with saline or WAY208466. Two separate sets of animals were used for short term memory (tested 1 h post-training) or long term memory (tested 24 h post-training). WAY208466 improved both short and long term memories, evaluated by the latency to enter the dark compartment, in the PA. The WAY208466-treated animals also showed more grooming and rearing in the light compartment. To better understand the molecular mechanisms and brain regions involved in the facilitation of emotional learning by WAY208466, we studied its effects on signal transduction and immediate early gene expression. WAY208466 increased the levels of phospho-Ser845-GluA1 and phospho-Ser217/221-MEK in the caudate-putamen. Levels of phospho-Thr202/204-Erk1/2 and the ratio mature BDNF/proBDNF were increased in the hippocampus. Moreover, WAY208466 increased c-fos in the hippocampus and Arc expression in both hippocampus and prefrontal cortex (PFC). The results indicate antidepressant efficacy and facilitation of emotional learning by 5-HT6 receptor agonism via

  11. 5-HT7 receptor signaling: improved therapeutic strategy in gut disorders.

    PubMed

    Kim, Janice J; Khan, Waliul I

    2014-01-01

    Serotonin (5-hydroxytryptamine; 5-HT) is most commonly known for its role as a neurotransmitter in the central nervous system (CNS). However, the majority of the body's 5-HT is produced in the gut by enterochromaffin (EC) cells. Alterations in 5-HT signaling have been associated with various gut disorders including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and enteric infections. Recently, our studies have identified a key role for 5-HT in the pathogenesis of experimental colitis. 5-HT7 receptors are expressed in the gut and very recently, we have shown evidence of 5-HT7 receptor expression on intestinal immune cells and demonstrated a key role for 5-HT7 receptors in generation of experimental colitis. This review summarizes the key findings of these studies and provides a comprehensive overview of our current knowledge of the 5-HT7 receptor in terms of its pathophysiological relevance and therapeutic potential in intestinal inflammatory conditions, such as IBD.

  12. Adult AMPA GLUA1 receptor subunit loss in 5-HT neurons results in a specific anxiety-phenotype with evidence for dysregulation of 5-HT neuronal activity.

    PubMed

    Weber, Tillmann; Vogt, Miriam A; Gartside, Sarah E; Berger, Stefan M; Lujan, Rafael; Lau, Thorsten; Herrmann, Elke; Sprengel, Rolf; Bartsch, Dusan; Gass, Peter

    2015-05-01

    Both the glutamatergic and serotonergic (5-HT) systems are implicated in the modulation of mood and anxiety. Descending cortical glutamatergic neurons regulate 5-HT neuronal activity in the midbrain raphe nuclei through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors. To analyze the functional role of GLUA1-containing AMPA receptors in serotonergic neurons, we used the Cre-ERT2/loxP-system for the conditional inactivation of the GLUA1-encoding Gria1 gene selectively in 5-HT neurons of adult mice. These Gria1(5-HT-/-) mice exhibited a distinct anxiety phenotype but showed no alterations in locomotion, depression-like behavior, or learning and memory. Increased anxiety-related behavior was associated with significant decreases in tryptophan hydroxylase 2 (TPH2) expression and activity, and subsequent reductions in tissue levels of 5-HT, its metabolite 5-hydroxyindoleacetic acid (5-HIAA), and norepinephrine in the raphe nuclei. However, TPH2 expression and activity as well as monoamine levels were unchanged in the projection areas of 5-HT neurons. Extracellular electrophysiological recordings of 5-HT neurons revealed that, while α1-adrenoceptor-mediated excitation was unchanged, excitatory responses to AMPA were enhanced and the 5-HT1A autoreceptor-mediated inhibitory response to 5-HT was attenuated in Gria1(5-HT-/-) mice. Our data show that a loss of GLUA1 protein in 5-HT neurons enhances AMPA receptor function and leads to multiple local molecular and neurochemical changes in the raphe nuclei that dysregulate 5-HT neuronal activity and induce anxiety-like behavior.

  13. Characterization of the 5-HT receptor subtypes involved in the motor behaviours produced by intrathecal administration of 5-HT agonists in rats.

    PubMed Central

    Fone, K. C.; Robinson, A. J.; Marsden, C. A.

    1991-01-01

    1. The motor behavioural effects of intrathecal injections of 5-hydroxytryptamine (5-HT) and a variety of 5-HT receptor agonists were examined in adult Wistar rats to establish; (a) which 5-HT receptor subtype/s elicit each behaviour and (b) whether these receptors are located within the spinal cord. 2. Intrathecal injection of 5-methoxy-N,N'-dimethyltryptamine (5-MeODMT), (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI) or 2,5-dimethoxy-alpha,4-dimethylbenzene ethamine hydrochloride (DOM) produced dose-related back muscle contractions (BMC) and wet dog shakes (WDS) which were both markedly attenuated by intraperitoneal pretreatment with either ritanserin (1 mg kg-1), ketanserin (0.16 mg kg-1) or mianserin (0.6 mg kg-1) indicating the involvement of 5-HT2 receptors in both these motor behaviours. Both fluoxetine (1-20 mg kg-1, i.p.) and high doses of 5-HT (50 micrograms) following fluoxetine (5 mg kg-1, i.p.) also elicited BMC, further confirming the involvement of 5-HT in this behaviour. 3. Intrathecal 5-carboxamidotryptamine (5-CT) evoked a marked wet-dog shake response without producing any BMC. Intrathecal pretreatment with 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT) enhanced, while in contrast 2-methyl-5-HT pretreatment attenuated, 5-HT agonist-induced BMC without affecting WDS. These data suggest that the spinal 5-HT2 receptors mediating BMC are positively modulated by 5-HT1A but negatively influenced by 5-HT3 receptor activation and may be of a different subtype to the supra-spinal 5-HT2 receptors which elicit WDS.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1 Figure 5 PMID:1832068

  14. Ethanol and Mesolimbic Serotonin/Dopamine Interactions Via 5-HT1B Receptors

    DTIC Science & Technology

    2006-03-01

    5 - HT3 receptor antagonist antagonized systemic ethanol- induced increases of DA release in the VTA [10] or the NACC [9]. Moreover, the...experiments with a selective 5 -HT1B receptor antagonist such as SB 216641 are required to strengthen this conclusion. The future experiments will be... receptor antagonist ), but not BRL 15572 (a 5 -HT1D/1A receptor antagonist ) or WAY 100635 (a 5 -HT1A receptor antagonist ). Administration

  15. Role of dorsal raphe nucleus 5-HT(1A) and 5-HT(2) receptors in tonic immobility modulation in guinea pigs.

    PubMed

    Ferreira, Mateus Dalbem; Menescal-de-Oliveira, Leda

    2009-08-18

    Tonic immobility (TI) is an innate defensive behavior characterized by a state of physical inactivity and diminished responsiveness to environmental stimuli. Behavioral adaptations to changes in the external and internal milieu involve complex neuronal network activity and a large number of chemical neurotransmitters. The TI response is thought to be influenced by serotonin (5-HT) activity in the central nervous system (CNS) of vertebrates, but the neuronal groups involved in the mechanisms underlying this behavior are poorly understood. Owing to its extensive afferents and efferents, the dorsal raphe nucleus (DRN) has been implicated in a great variety of physiological and behavioral functions. In the current study, we investigated the influence of serotonergic 5-HT(1A) and 5-HT(2) receptor activity within the DRN on the modulation of TI behavior in the guinea pig. Microinjection of a 5-HT(1A) receptor agonist (8-OH-DPAT, 0.01 and 0.1 microg) decreased TI behavior, an effect blocked by pretreatment with WAY-100635 (0.033 microg), a 5-HT(1A) antagonist. In contrast, activation of 5-HT(2) receptors within the DRN (alpha-methyl-5-HT, 0.5 microg) increased the TI duration, and this effect could be reversed by pretreatment with an ineffective dose (0.01 microg) of ketanserine. Since the 5-HT(1A) and 5-HT(2) agonists decreased and increased, respectively, the duration of TI, different serotonin receptor subtypes may play distinct roles in the modulation of TI in the guinea pig.

  16. Autoradiographic evaluation of [3H]CUMI-101, a novel, selective 5-HT1AR ligand in human and baboon brain

    PubMed Central

    Dileep Kumar, J. S.; Parsey, Ramin V.; Kassir, Suham A.; Majo, Vattoly J.; Milak, Matthew S.; Prabhakaran, Jaya; Underwood, Mark D.; Mann, J. John; Arango, Victoria

    2014-01-01

    [11C]CUMI-101 is the first selective serotonin receptor (5-HT1AR) partial agonist radiotracer for positron emission tomography (PET) tested in vivo in nonhuman primates and humans. We evaluated specific binding of [3H]CUMI-101 by quantitative autoradiography studies in postmortem baboon and human brain sections using the 5- HT1AR antagonist WAY100635 as a displacer. The regional and laminar distributions of [3H]CUMI-101 binding in baboon and human brain sections matched the known distribution of [3H]8-OH-DPAT and [3H]WAY100635. Prazosin did not measurably displace [3H]CUMI-101 binding in baboon or human brain sections, thereby ruling out [3H]CUMI-101 binding to α1-adrenergic receptors. This study demonstrates that [11C]CUMI-101 is a selective 5-HT1AR ligand for in vivo and in vitro studies in baboon and human brain. PMID:23454434

  17. Neuronal localization of the 5-HT2 receptor family in the amygdaloid complex.

    PubMed

    Bombardi, Cristiano

    2014-01-01

    The amygdaloid complex (or amygdala), a heterogeneous structure located in the medial portion of the temporal lobe, is composed of deep, superficial, and "remaining" nuclei. This structure is involved in the generation of emotional behavior, in the formation of emotional memories and in the modulation of the consolidation of explicit memories for emotionally arousing events. The serotoninergic fibers originating in the dorsal and medial raphe nuclei are critically involved in amygdalar functions. Serotonin (5-hydroxytryptamine, 5-HT) regulates amygdalar activity through the activation of the 5-HT2 receptor family, which includes three receptor subtypes: 5-HT2A, 5-HT2B, and 5-HT2C. The distribution and the functional activity of the 5-HT2 receptor family has been studied more extensively than that of the 5-HT2A receptor subtypes, especially in the deep nuclei. In these nuclei, the 5-HT2A receptor is expressed on both pyramidal and non-pyramidal neurons, and could play a critical role in the formation of emotional memories. However, the exact role of the 5-HT2A receptor subtypes, as well as that of the 5-HT2B and 5-HT2C receptor subtypes, in the modulation of the amygdalar microcircuits requires additional study. The present review reports data concerning the distribution and the functional roles of the 5-HT2 receptor family in the amygdala.

  18. Evidence that the anorexia induced by lipopolysaccharide is mediated by the 5-HT2C receptor.

    PubMed

    von Meyenburg, Claudia; Langhans, Wolfgang; Hrupka, Brian J

    2003-01-01

    Rats consistently reduce their food intake following injections of bacterial lipopolysaccharides (LPS). Because inhibition of serotonergic (5-HT) activity by 8-OH-DPAT (5-HT(1A) activation) attenuates LPS-induced anorexia, we conducted a series of studies to examine whether other 5-HT-receptors are involved in the mediation of peripheral LPS-induced anorexia. In all experiments, rats were injected with LPS (100 microg/kg body weight [BW] ip) at lights out (hour 0). Antagonists were administered peripherally at hour 4, shortly after the onset of anorexia, which presumably follows the enhanced cytokine production after LPS. Food intake was then recorded during the subsequent 2 h or longer. 5-HT receptor antagonists cyanopindolol and SB 224289 (5-HT(1B)), ketanserin (5-HT(2A)), RS-102221 (5-HT(2C)), and metoclopramide (5-HT(3)) failed to attenuate LPS-induced anorexia. In contrast, both ritanserin (5-HT(2A/C)-receptor antagonist) (0.5 mg/kg BW) and SB 242084 (5-HT(2C)) (0.3 mg/kg BW) attenuated LPS-induced anorexia at doses that did not alter food intake in non-LPS-treated rats (all P<.01). Our results suggest that at least part of the anorexia following peripheral LPS administration is mediated through an enhanced 5-HT-ergic activity and the 5-HT(2C) receptor.

  19. 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

  20. Transcriptional regulation of the 5-HT1A receptor: implications for mental illness.

    PubMed

    Albert, Paul R

    2012-09-05

    The serotonin-1A (5-HT(1A)) receptor is an abundant post-synaptic 5-HT receptor (heteroreceptor) implicated in regulation of mood, emotion and stress responses and is the major somatodendritic autoreceptor that negatively regulates 5-HT neuronal activity. Based on animal models, an integrated model for opposing roles of pre- and post-synaptic 5-HT(1A) receptors in anxiety and depression phenotypes and response to antidepressants is proposed. Understanding differential transcriptional regulation of pre- versus post-synaptic 5-HT(1A) receptors could provide better tools for their selective regulation. This review examines the transcription factors that regulate brain region-specific basal and stress-induced expression of the 5-HT(1A) receptor gene (Htr1a). A functional polymorphism, rs6295 in the Htr1a promoter region, blocks the function of specific repressors Hes1, Hes5 and Deaf1, resulting in increased 5-HT(1A) autoreceptor expression in animal models and humans. Its association with altered 5-HT(1A) expression, depression, anxiety and antidepressant response are related to genotype frequency in different populations, sample homogeneity, disease outcome measures and severity. Preliminary evidence from gene × environment studies suggests the potential for synergistic interaction of stress-mediated repression of 5-HT(1A) heteroreceptors, and rs6295-induced upregulation of 5-HT(1A) autoreceptors. Targeted therapeutics to inhibit 5-HT(1A) autoreceptor expression and induce 5-HT(1A) heteroreceptor expression may ameliorate treatment of anxiety and major depression.

  1. Immunohistological localization of 5-HT in the CNS and feeding system of the Stable Fly

    Technology Transfer Automated Retrieval System (TEKTRAN)

    5-HT immunoreactive neurons were detected in the CNS of the stable fly. The finding of strong innervations of the cibarial pump muscles and the foregut by 5-HT IR neurons in the feeding-related systems suggests that 5-HT may play a crucial role in the control of the feeding behavior in both the larv...

  2. 5-Hydroxytryptamine (5-HT)4 receptors in post mortem human brain tissue: distribution, pharmacology and effects of neurodegenerative diseases.

    PubMed Central

    Reynolds, G P; Mason, S L; Meldrum, A; De Keczer, S; Parnes, H; Eglen, R M; Wong, E H

    1995-01-01

    1. The distribution, pharmacology and effects of neurodegenerative diseases on 5-HT4 receptors in human brain have been characterized in vitro. 2. The 5-HT4 receptor in post mortem human brain tissue was specifically labelled with [3H]-GR 113808. In human putamen, this ligand labelled a homogeneous population of sites, with an apparent affinity (-log Kd) of 10.1 and a density (Bmax) of 5.73 fmol mg-1 tissue. The pharmacology of this site was characterized by use of a series of displacing ligands, and the following rank order of apparent affinities (with mean +/- s.d. -log Ki values in parentheses) was generated: GR113808 (10.05 +/- 0.04) > SDZ 205,557 (8.65 +/- 0.08) > DAU 6285 (7.95 +/- 0.04) > BIMU-1 (7.81 +/- 0.06) > DAU 6215 (7.42 +/- 0.23) > tropisetron (7.39 +/- 0.23) > 5-HT (7.32 +/- 1.00) > BIMU-8 (7.25 +/- 0.04) > (R)-zacopride (5.82 +/- 0.04). The Hill coefficients were not significantly different from unity, consistent with an interaction at a single site. A comparison of the affinities of these compounds with those obtained from guinea-pig striatum indicated no evidence of species differences. 3. The regional distribution of 5-HT4 receptors was assessed by determining the density of binding sites for [3H]-GR 113808.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7780656

  3. The 5-HT1A serotonin receptor is located on calbindin- and parvalbumin-containing neurons in the rat brain.

    PubMed

    Aznar, Susana; Qian, Zhaoxia; Shah, Reshma; Rahbek, Birgitte; Knudsen, Gitte M

    2003-01-03

    The 5-HT(1A) receptor is a well-characterized serotonin receptor playing a role in many central nervous functions and known to be involved in depression and other mental disorders. In situ hybridization, immunocytochemical, and binding studies have shown that the 5-HT(1A) receptor is widely distributed in the rat brain, with a particularly high density in the limbic system. The receptor's localization in the different neuronal subtypes, which may be of importance for understanding its role in neuronal circuitries, is, however, unknown. In this study we show by immunocytochemical double-labeling techniques, that the 5-HT(1A) receptor is present on both pyramidal and principal cells, and calbindin- and parvalbumin-containing neurons, which generally define two different subtypes of interneurons. Moreover, semiquantitative analysis showed that the receptor's distribution in the different neuronal types varies between brain areas. In cortex, hippocampus, hypothalamus, and amygdala the receptor was located on both principal cells and calbindin- and parvalbumin-containing neurons. In septum and thalamus, the receptor was mostly present on calbindin- and parvalbumin-containing cells. Especially in the medial septum and thalamic reticular nucleus, the receptor highly colocalized with parvalbumin-positive neurons. These results suggest a diverse function of the 5-HT(1A) receptor in modulating neuronal circuitry in different brain areas, that may depend on the type of neuron the receptor is predominantly located on.

  4. Oleanolic acid acrylate elicits antidepressant-like effect mediated by 5-HT1A receptor

    PubMed Central

    Fajemiroye, James O.; Polepally, Prabhakar R.; Chaurasiya, Narayan D.; Tekwani, Babu L.; Zjawiony, Jordan K.; Costa, Elson A.

    2015-01-01

    The development of new drugs for the treatment of depression is strategic to achieving clinical needs of patients. This study evaluates antidepressant-like effect and neural mechanisms of four oleanolic acid derivatives i.e. acrylate (D1), methacrylate (D2), methyl fumarate (D3) and ethyl fumarate (D4). All derivatives were obtained by simple one-step esterification of oleanolic acid prior to pharmacological screening in the forced swimming (FS) and open field (OF) tests. Pharmacological tools like α-methyl-p-tyrosine (AMPT, catecholamine depletor), p-chlorophenylalanine (serotonin depletor), prazosin (PRAZ, selective α1-receptor antagonist), WAY-100635 (selective serotonin 5-HT1A receptor antagonist) as well as monoamine oxidase (MAO) and functional binding assays were conducted to investigate possible neural mechanisms. In the FS test, D1 showed the most promising antidepressant-like effect without eliciting locomotor incoordination. Unlike group of mice pretreated with AMPT 100 mg/kg, PCPA 100 mg/kg or PRAZ 1 mg/kg, the effect of D1 was attenuated by WAY-100635 0.3 mg/kg pretreatment. D1 demonstrated moderate inhibition of MAO-A (IC50 = 48.848 ± 1.935 μM), potency (pEC50 = 6.1 ± 0.1) and intrinsic activity (Emax = 26 ± 2.0%) on 5-HT1A receptor. In conclusion, our findings showed antidepressant-like effect of D1 and possible involvement of 5-HT1A receptor. PMID:26199018

  5. Brown adipose tissue sympathetic nerve activity is potentiated by activation of 5-hydroxytryptamine (5-HT)1A/5-HT7 receptors in the rat spinal cord

    PubMed Central

    Madden, C. J.; Morrison, S. F.

    2008-01-01

    In urethane-chloralose anesthetized, neuromuscularly blocked, ventilated rats, microinjection of NMDA (12 pmol) into the right fourth thoracic segment (T4) spinal intermediolateral nucleus (IML) immediately increased ipsilateral brown adipose tissue (BAT) sympathetic nerve activity (SNA; peak +492% of control), expired CO2 (+0.1%) heart rate (+48 beats min−1) and arterial pressure (+8 mmHg). The increase in BAT SNA evoked by T4 IML microinjection of NMDA was potentiated when it was administered immediately following a T4 IML microinjection of 5-hydroxytryptamine (5-HT, 100 pmol) or the 5-HT1A/5-HT7 receptor agonist, 8-OH-DPAT (600 pmol), (area under the curve: 184%, and 259% of the NMDA-only response, respectively). In contrast, T4 IML microinjection of the 5-HT2 receptor agonist, DOI (28 pmol) did not potentiate the NMDA-evoked increase in BAT SNA (101% of NMDA-only response). Microinjection into the T4 IML of the selective 5-HT1A antagonist, WAY-100635 (500 pmol), plus the 5-HT7 antagonist, SB-269970 (500 pmol), prevented the 5-HT-induced potentiation of the NMDA-evoked increase in BAT SNA. When administered separately, WAY-100635 (800 pmol) and SB-269970 (800 pmol) attenuated the 8-OH-DPAT-induced potentiation of the NMDA-evoked increase in BAT SNA through effects on the amplitude and duration of the response, respectively. The selective 5-HT2 receptor antagonist, ketanserin (100 pmol), did not attenuate the potentiations of the NMDA-evoked increase in BAT SNA induced by either 5-HT or 8-OH-DPAT. These results demonstrate that activation of 5-HT1A/5-HT7 receptors can act synergistically with NMDA receptor activation within the IML to markedly increase BAT SNA. PMID:18082230

  6. Role of 5-HT5A and 5-HT1B/1D receptors in the antinociception produced by ergotamine and valerenic acid in the rat formalin test.

    PubMed

    Vidal-Cantú, Guadalupe C; Jiménez-Hernández, Mildred; Rocha-González, Héctor I; Villalón, Carlos M; Granados-Soto, Vinicio; Muñoz-Islas, Enriqueta

    2016-06-15

    Sumatriptan, dihydroergotamine and methysergide inhibit 1% formalin-induced nociception by activation of peripheral 5-HT1B/1D receptors. This study set out to investigate the pharmacological profile of the antinociception produced by intrathecal and intraplantar administration of ergotamine (a 5-HT1B/1D and 5-HT5A/5B receptor agonist) and valerenic acid (a partial agonist at 5-HT5A receptors). Intraplantar injection of 1% formalin in the right hind paw resulted in spontaneous flinching behavior of the injected hindpaw of female Wistar rats. Intrathecal ergotamine (15nmol) or valerenic acid (1 nmol) blocked in a dose dependent manner formalin-induced nociception. The antinociception by intrathecal ergotamine (15nmol) or valerenic acid (1nmol) was partly or completely blocked by intrathecal administration of the antagonists: (i) methiothepin (non-selective 5-HT5A/5B; 0.01-0.1nmol); (ii) SB-699551 (selective 5-HT5A; up to 10nmol); (iii) anti-5-HT5A antibody; (iv) SB-224289 (selective 5-HT1B; 0.1-1nmol); or (v) BRL-15572 (selective 5-HT1D; 0.1-1nmol). Likewise, antinociception by intraplantar ergotamine (15nmol) and valerenic acid (10nmol) was: (i) partially blocked by methiothepin (1nmol), SB-699551 (10nmol) or SB-224289 (1nmol); and (ii) abolished by BRL-15572 (1nmol). The above doses of antagonists (which did not affect per se the formalin-induced nociception) were high enough to completely block their respective receptors. Our results suggest that ergotamine and valerenic acid produce antinociception via 5-HT5A and 5-HT1B/1D receptors located at both spinal and peripheral sites. This provides new evidence for understanding the modulation of nociceptive pathways in inflammatory pain.

  7. Studies of the biogenic amine transporters. VII. Characterization of a novel cocaine binding site identified with [125I]RTI-55 in membranes prepared from human, monkey and guinea pig caudate.

    PubMed

    Rothman, R B; Silverthorn, M L; Glowa, J R; Matecka, D; Rice, K C; Carroll, F I; Partilla, J S; Uhl, G R; Vandenbergh, D J; Dersch, C M

    1998-04-01

    [125I]RTI-55 is a cocaine analog with high affinity for dopamine (DA) and serotonin (5-HT) transporters. Quantitative ligand binding studies revealed a novel high affinity [125I]RTI-55 binding site assayed under 5-HT transporter (SERT) conditions which has low affinity for almost all classic biogenic amine transporter ligands, including high affinity 5-HT transporter inhibitors such as paroxetine, but which retains high affinity for cocaine analogs. This site, termed SERT(site2) for its detection under 5-HT transporter conditions (not for an association with the SERT) occurs in monkey caudate, human caudate, and guinea pig caudate membranes, but not in rat caudate membranes. SERT(site2) is distinguished from the DA transporter (DAT) and SERT by several criteria, including a distinct ligand-selectivity profile, the inability to detect SERT(site2) in cells stably expressing the cloned human DAT, and insensitivity to irreversible ligands which inhibit [125I]RTI-55 binding to the DAT and SERT. Perhaps the most striking finding about SERT(site2) is that a wide range of representative antidepressant agents have very low affinity for SERT(site2). The affinity of cocaine for this site is not very different from the concentration cocaine achieves in the brain at pharmacological doses. Viewed collectively with the observation that ligands with high affinity for SERT(site2) are mostly cocaine analogs, these data lead us to speculate that actions of cocaine which differ from those of classic biogenic amine uptake inhibitors may be mediated in part via SERT(site2).

  8. The Role of 5-HT3 Receptors in Signaling from Taste Buds to Nerves.

    PubMed

    Larson, Eric D; Vandenbeuch, Aurelie; Voigt, Anja; Meyerhof, Wolfgang; Kinnamon, Sue C; Finger, Thomas E

    2015-12-02

    Activation of taste buds triggers the release of several neurotransmitters, including ATP and serotonin (5-hydroxytryptamine; 5-HT). Type III taste cells release 5-HT directly in response to acidic (sour) stimuli and indirectly in response to bitter and sweet tasting stimuli. Although ATP is necessary for activation of nerve fibers for all taste stimuli, the role of 5-HT is unclear. We investigated whether gustatory afferents express functional 5-HT3 receptors and, if so, whether these receptors play a role in transmission of taste information from taste buds to nerves. In mice expressing GFP under the control of the 5-HT(3A) promoter, a subset of cells in the geniculate ganglion and nerve fibers in taste buds are GFP-positive. RT-PCR and in situ hybridization confirmed the presence of 5-HT(3A) mRNA in the geniculate ganglion. Functional studies show that only those geniculate ganglion cells expressing 5-HT3A-driven GFP respond to 10 μM 5-HT and this response is blocked by 1 μM ondansetron, a 5-HT3 antagonist, and mimicked by application of 10 μM m-chlorophenylbiguanide, a 5-HT3 agonist. Pharmacological blockade of 5-HT3 receptors in vivo or genetic deletion of the 5-HT3 receptors reduces taste nerve responses to acids and other taste stimuli compared with controls, but only when urethane was used as the anesthetic. We find that anesthetic levels of pentobarbital reduce taste nerve responses apparently by blocking the 5-HT3 receptors. Our results suggest that 5-HT released from type III cells activates gustatory nerve fibers via 5-HT3 receptors, accounting for a significant proportion of the neural taste response.

  9. Methylenedioxymethamphetamine induces spontaneous tail-flicks in the rat via 5-HT1A receptors.

    PubMed

    Millan, M J; Colpaert, F C

    1991-02-07

    In rats lightly restrained in horizontal cylinders, (+/-)-3,4-methylenedioxymethamphetamine (MDMA) dose dependently (0.16-10.0 mg/kg, s.c.) elicited spontaneous tail-flicks; that is, tail-flicks in the absence of extraneous stimulation. In contrast, amphetamine over a similar dose-range was inactive. Selective inhibitors of 5-hydroxytryptamine (5-HT) uptake and carrier-mediated 5-HT release, paroxetine and citalopram, did not induce spontaneous tail-flicks themselves and blocked those induced by MDMA. In distinction, maprotiline and bupropion, selective inhibitors of noradrenaline and dopamine uptake, respectively, failed to modify the action of MDMA. Spontaneous tail-flicks elicited by MDMA were unaffected by the selective 5-HT3 receptor antagonists, ICS 205,930 and GR 38032F. They were attenuated by the mixed 5-HT1/5-HT2 receptor antagonist, methiotepin, the mixed 5-HT1A/5-HT1B receptor antagonist, (-)-alprenolol and the mixed 5-HT1A/5-HT2 receptor antagonist, spiperone, but not by the selective 5-HT1C/5-HT2 receptor antagonists, ritanserin, ICI 169,369 and ketanserin. The novel 5-HT1A receptor antagonists, BMY 7378 and NAN-190, each abolished MDMA-evoked spontaneous tail-flicks. Selective D1, D2, alpha 1, alpha 2, beta 1 and beta 2 antagonists had little influence upon induction of spontaneous tail-flicks by MDMA. These data indicate that MDMA evokes spontaneous tail-flicks in the rat via a release of 5-HT which acts at 5-HT1A receptors. Thus, 5-HT1A receptors appear to be involved in the acute functional actions of MDMA.

  10. Differences in 5-HT2A and mGlu2 Receptor Expression Levels and Repressive Epigenetic Modifications at the 5-HT2A Promoter Region in the Roman Low- (RLA-I) and High- (RHA-I) Avoidance Rat Strains.

    PubMed

    Fomsgaard, Luna; Moreno, Jose L; de la Fuente Revenga, Mario; Brudek, Tomasz; Adamsen, Dea; Rio-Alamos, Cristobal; Saunders, Justin; Klein, Anders Bue; Oliveras, Ignasi; Cañete, Toni; Blazquez, Gloria; Tobeña, Adolf; Fernandez-Teruel, Albert; Gonzalez-Maeso, Javier; Aznar, Susana

    2017-03-06

    The serotonin 2A (5-HT2A) and metabotropic glutamate 2 (mGlu2) receptors regulate each other and are associated with schizophrenia. The Roman high- (RHA-I) and the Roman low- (RLA-I) avoidance rat strains present well-differentiated behavioral profiles, with the RHA-I strain emerging as a putative genetic rat model of schizophrenia-related features. The RHA-I strain shows increased 5-HT2A and decreased mGlu2 receptor binding levels in prefrontal cortex (PFC). Here, we looked for differences in gene expression and transcriptional regulation of these receptors. The striatum (STR) was included in the analysis. 5-HT2A, 5-HT1A, and mGlu2 mRNA and [(3)H]ketanserin binding levels were measured in brain homogenates. As expected, 5-HT2A binding was significantly increased in PFC in the RHA-I rats, while no difference in binding was observed in STR. Surprisingly, 5-HT2A gene expression was unchanged in PFC but significantly decreased in STR. mGlu2 receptor gene expression was significantly decreased in both PFC and STR. No differences were observed for the 5-HT1A receptor. Chromatin immunoprecipitation assay revealed increased trimethylation of histone 3 at lysine 27 (H3K27me3) at the promoter region of the HTR2A gene in the STR. We further looked at the Akt/GSK3 signaling pathway, a downstream point of convergence of the serotonin and glutamate system, and found increased phosphorylation levels of GSK3β at tyrosine 216 and increased β-catenin levels in the PFC of the RHA-I rats. These results reveal region-specific regulation of the 5-HT2A receptor in the RHA-I rats probably due to absence of mGlu2 receptor that may result in differential regulation of downstream pathways.

  11. Kinetic modeling of the serotonin 5-HT1B receptor radioligand [11C]P943 in humans

    PubMed Central

    Gallezot, Jean-Dominique; Nabulsi, Nabeel; Neumeister, Alexander; Planeta-Wilson, Beata; Williams, Wendol A; Singhal, Tarun; Kim, Sunhee; Maguire, R Paul; McCarthy, Timothy; Frost, J James; Huang, Yiyun; Ding, Yu-Shin; Carson, Richard E

    2010-01-01

    [11C]P943 is a new radioligand recently developed to image and quantify serotonin 5-Hydroxytryptamine (5-HT1B) receptors with positron emission tomography (PET). The purpose of this study was to evaluate [11C]P943 for this application in humans, and to determine the most suitable quantification method. Positron emission tomography data and arterial input function measurements were acquired in a cohort of 32 human subjects. Using arterial input functions, compartmental modeling, the Logan graphical analysis, and the multilinear method MA1 were tested. Both the two tissue-compartment model and MA1 provided good fits of the PET data and reliable distribution volume estimates. Using the cerebellum as a reference region, BPND binding potential estimates were computed. [11C]P943 BPND estimates were significantly correlated with in vitro measurements of the density of 5-HT1B receptors, with highest values in the occipital cortex and pallidum. To evaluate noninvasive methods, two- and three-parameter graphical analyses, Simplified Reference Tissue Models (SRTM and SRTM2), and Multilinear Reference Tissue Models (MRTM and MRTM2) were tested. The MRTM2 model provided the best correlation with MA1 binding-potential estimates. Parametric images of the volume of distribution or binding potential of [11C]P943 could be computed using both MA1 and MRTM2. The results show that [11C]P943 provides quantitative measurements of 5-HT1B binding potential. PMID:19773803

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

    PubMed

    Viñals, Xavier; Moreno, Estefanía; 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

    2015-07-01

    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.

  13. 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

  14. Molecular and functional characterization of proteins interacting with the C-terminal domains of 5-HT2 receptors: emergence of 5-HT2 "receptosomes".

    PubMed

    Gavarini, Sophie; Bécamel, Carine; Chanrion, Benjamin; Bockaert, Joël; Marin, Philippe

    2004-06-01

    Many cellular functions are carried out by multiprotein complexes. The last five years of research have revealed that many G-protein coupled receptor (GPCR) functions that are not mediated by G proteins involve protein networks, which interact with their intracellular domains. This review focuses on one family of GPCRs activated by serotonin, the 5-HT(2) receptor family, which comprises three closely related subtypes, the 5-HT(2A), the 5-HT(2B) and the 5-HT(2c) receptors. These receptors still raise particular interest, because a large number of psychoactive drugs including hallucinogens, anti-psychotics, anxiolytics and anti-depressants, mediate their action, at least in part, through activation of 5-HT(2) receptors. Recent studies based on two-hybrid screens, proteomic, biochemical and cell biology approaches, have shown that the C-terminal domains of 5-HT(2) receptors interact with intracellular proteins. To date, the protein network associated with the C-terminus of the 5-HT(2C) receptor has been the most extensively characterized, using a proteomic approach combining affinity chromatography, mass spectrometry and immunoblotting. It includes scaffolding proteins containing one or several PDZ domains, signalling proteins and proteins of the cytoskeleton. Data indicating that the protein complexes interacting with 5-HT(2) receptor C-termini tightly control receptor trafficking and receptor-mediated signalling will also be reviewed.

  15. Fluvoxamine, a selective serotonin reuptake inhibitor, and 5-HT2C receptor inactivation induce appetite-suppressing effects in mice via 5-HT1B receptors.

    PubMed

    Nonogaki, Katsunori; Nozue, Kana; Takahashi, Yukiko; Yamashita, Nobuyuki; Hiraoka, Shuichi; Kumano, Hiroaki; Kuboki, Tomifusa; Oka, Yohsitomo

    2007-10-01

    Serotonin (5-hydroxytryptamine; 5-HT) 2C receptors and the downstream melanocortin pathway are suggested to mediate the appetite-suppressing effects of 5-HT drugs such as m-chlorophenylpiperazine (mCPP) and fenfluramine. Here, we report that fluvoxamine (3-30 mg/kg), a selective serotonin reuptake inhibitor (SSRI), in the presence of SB 242084 (1-2 mg/kg), a selective 5-HT2C receptor antagonist, exerts appetite-suppressing effects while fluvoxamine or SB 242084 alone has no effect. The appetite-suppressing effects were attenuated in the presence of SB 224289 (5 mg/kg), a selective 5-HT1B receptor antagonist. Moreover, CP 94253 (5-10 mg/kg), a selective 5-HT1B receptor agonist, exerted appetite-suppressing effects and significantly increased hypothalamic pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) gene expression and decreased hypothalamic orexin gene expression. These results suggest that fluvoxamine and inactivation of 5-HT2C receptors exert feeding suppression through activation of 5-HT1B receptors, and that 5-HT1B receptors up-regulate hypothalamic POMC and CART gene expression and down-regulate hypothalamic orexin gene expression in mice.

  16. Downregulated hypothalamic 5-HT3 receptor expression and enhanced 5-HT3 receptor antagonist-mediated improvement in fatigue-like behaviour in cholestatic rats.

    PubMed

    Nguyen, H; Wang, H; le, T; Ho, W; Sharkey, K A; Swain, M G

    2008-03-01

    The serotonin neurotransmitter system, including the 5-HT(3) receptor, has been implicated in the genesis of fatigue in patients with liver disease. Therefore, we examined the possible role of 5-HT(3) receptors in cholestasis-associated fatigue. Rats were either bile duct resected (BDR) or sham resected and studied 10 days postsurgery. A significant decrease in hypothalamic 5-HT(3) receptor expression was detected by immunohistochemistry and Western blot in BDR vs sham rats, coupled with increased hypothalamic serotonin turnover identified by an elevated 5-hydroxyindoleacetic acid (5-HIAA) to 5-HT ratio in BDR vs sham rats. To examine fatigue-like behaviour, an activity meter was used. BDR rats exhibited significantly lower locomotor activity than did sham animals. Subcutaneous injection of the 5-HT(3) receptor antagonist tropisetron (0.1 mg kg(-1)) resulted in significantly increased locomotor activity in BDR rats compared to the activity in saline-treated controls, but was without effect in sham rats. However, a 10-fold higher dose of tropisetron significantly increased locomotor activity in both BDR and sham rats compared to saline-injected controls. These findings indicate that cholestasis in the rat is associated with increased hypothalamic serotonin turnover, decreased hypothalamic 5-HT(3) receptor expression, and enhanced sensitivity to locomotor activation induced by 5-HT(3) receptor antagonism, thereby implicating the 5-HT(3) receptor system in cholestasis associated fatigue.

  17. 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.

  18. The 5-HT deficiency theory of depression: perspectives from a naturalistic 5-HT deficiency model, the tryptophan hydroxylase 2Arg439His knockin mouse

    PubMed Central

    Jacobsen, Jacob P. R.; Medvedev, Ivan O.; Caron, Marc G.

    2012-01-01

    A decreased level of brain 5-hydroxytryptamine (5-HT) has been theorized to be a core pathogenic factor in depression for half a century. The theory arose from clinical observations that drugs enhancing extracellular levels of 5-HT (5-HTExt) have antidepressant effects in many patients. However, whether such drugs indeed correct a primary deficit remains unresolved. Still, a number of anomalies in putative biomarkers of central 5-HT function have been repeatedly reported in depression patients over the past 40 years, collectively indicating that 5-HT deficiency could be present in depression, particularly in severely ill and/or suicidal patients. This body of literature on putative 5-HT biomarker anomalies and depression has recently been corroborated by data demonstrating that such anomalies indeed occur consequent to severely reduced 5-HTExt levels in a mouse model of naturalistic 5-HT deficiency, the tryptophan hydroxylase 2 His439 knockin (Tph2KI) mouse. In this review, we will critically assess the evidence for 5-HT deficiency in depression and the possible role of polymorphisms in the Tph2 gene as a causal factor in 5-HT deficiency, the latter investigated from a clinical as well as preclinical angle. PMID:22826344

  19. [CROSS-TALK BETWEEN 5-HT1A AND 5-HT7 RECEPTORS: ROLE IN THE AUTOREGULATION OF THE BRAIN SEROTONIN SYSTEM AND IN MECHANISM OF ANTIDEPRESSANTS ACTION].

    PubMed

    Popova, N K; Ponimaskin, E G; Naumenko, V S

    2015-11-01

    Recent studies considerably extended our knowledge of the mechanisms and physiological role of the interaction between different receptors in the brain. Current review summarizes data on the formation of receptor complexes and the role of such complexes in the autoregulation of the brain serotonin system, behavioral abnormalities and mechanism of antidepressants action. Particular attention is paid to 5-HT1A and 5-HT7 receptor heterodimers. The results described in the present review indicate that: i) dimerization and formation of mobile receptor complexes is a common feature for the members of G-protein coupled receptor superfamily; ii) 5-HT7 receptor appears to be a modulator for 5-HT1A receptor - the key autoregulator of the brain serotonin system; iii) 5-HT1A/5-HT7 receptor complexes formation is one of the mechanisms for inactivation and desensitization of the 5-HTIA receptors in the brain; iv) differences in the 5-HT7 receptor and 5-HTIA/5-HT7 heterodimers density define different sensitivity of pre- and postsynaptic 5-HTlA receptors to chronic treatment with selective serotonin reuptake inhibitors.

  20. In Vivo Effect of a 5-HT7 Receptor Agonist on 5-HT Neurons and GABA Interneurons in the Dorsal Raphe Nuclei of Sham and PD Rats.

    PubMed

    Wang, Shuang; Zhao, Yan; Gao, Jie; Guo, Yufang; Wang, Xiang; Huo, Jian; Wei, Ping; Cao, Jian

    2017-03-01

    The 5-hydroxytryptamine (5-HT; serotonin) neurotransmission is severely affected by the degeneration of nigrostriatal dopaminergic neurons. Here, we report the effects of the systemic administration of the 5-HT7 receptor agonist AS-19. In sham rats, the mean response of the 5-HT neurons in the dorsal raphe nucleus (DRN) to systemic AS-19 was excitatory and the mean response of the γ-aminobutyric acid (GABA) interneurons was inhibitory. In Parkinson disease (PD) rats, the same dose did not affect the 5-HT neurons and only high doses (640 μg/kg intravenous) were able to the increase GABA interneuron activity. These results indicate that DRN 5-HT neurons and GABA interneurons are regulated by the activation of 5-HT7 receptors and that the degeneration of the nigrostriatal pathway leads to decreased responses of these neurons to AS-19, which in turn suggests that the 5-HT7 receptors on 5-HT neurons and GABA interneurons in PD rats are dysfunctional and downregulated.

  1. What Do We Really Know About 5-HT1A Receptor Signaling in Neuronal Cells?

    PubMed Central

    Rojas, Paulina S.; Fiedler, Jenny L.

    2016-01-01

    Serotonin (5-HT) is a neurotransmitter that plays an important role in neuronal plasticity. Variations in the levels of 5-HT at the synaptic cleft, expression or dysfunction of 5-HT receptors may alter brain development and predispose to various mental diseases. Here, we review the transduction pathways described in various cell types transfected with recombinant 5-HT1A receptor (5-HT1AR), specially contrasting with those findings obtained in neuronal cells. The 5-HT1AR is detected in early stages of neural development and is located in the soma, dendrites and spines of hippocampal neurons. The 5-HT1AR differs from other 5-HT receptors because it is coupled to different pathways, depending on the targeted cell. The signaling pathway associated with this receptor is determined by Gα isoforms and some cascades involve βγ signaling. The activity of 5-HT1AR usually promotes a reduction in neuronal excitability and firing, provokes a variation in cAMP and Ca2+, levels which may be linked to specific types of behavior and cognition. Furthermore, evidence indicates that 5-HT1AR induces neuritogesis and synapse formation, probably by modulation of the neuronal cytoskeleton through MAPK and phosphoinositide-3-kinase (PI3K)-Akt signaling pathways. Advances in understanding the actions of 5-HT1AR and its association with different signaling pathways in the central nervous system will reveal their pivotal role in health and disease. PMID:27932955