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Sample records for 5-ht uptake inhibitor

  1. Endogenous 5-HT outflow from chicken aorta by 5-HT uptake inhibitors and amphetamine derivatives

    PubMed Central

    DELGERMURUN, Dugar; ITO, Shigeo; OHTA, Toshio; YAMAGUCHI, Soichiro; OTSUGURO, Ken-ichi

    2015-01-01

    Chemoreceptor cells aggregating in clusters in the chicken thoracic aorta contain 5-hydroxytryptamine (5-HT) and have voltage-dependent ion channels and nicotinic acetylcholine receptors, which are characteristics typically associated with neurons. The aim of the present study was to investigate the effects of 5-HT uptake inhibitors, fluvoxamine, fluoxetine and clomipramine (CLM), and amphetamine derivatives, p-chloroamphetamine (PCA) and methamphetamine (MET), on endogenous 5-HT outflow from the isolated chick thoracic aorta in vitro. 5-HT was measured by using a HPLC system with electrochemical detection. The amphetamine derivatives and 5-HT uptake inhibitors caused concentration-dependent increases in endogenous 5-HT outflow. PCA was about ten times more effective in eliciting 5-HT outflow than MET. The 5-HT uptake inhibitors examined had similar potency for 5-HT outflow. PCA and CLM increased 5-HT outflow in a temperature-dependent manner. The outflow of 5-HT induced by PCA or 5-HT uptake inhibitors was independent of extracellular Ca2+ concentration. The 5-HT outflow induced by CLM, but not that by PCA, was dependent on the extracellular NaCl concentration. These results suggest that the 5-HT uptake system of 5-HT-containing chemoreceptor cells in the chicken thoracic aorta has characteristics similar to those of 5-HT-containing neurons in the mammalian central nervous system (CNS). PMID:26321443

  2. Preclinical characterization of WAY-211612: a dual 5-HT uptake inhibitor and 5-HT1A receptor antagonist and potential novel antidepressant

    PubMed Central

    Beyer, CE; Lin, Q; Platt, B; Malberg, J; Hornby, G; Sullivan, KM; Smith, DL; Lock, T; Mitchell, PJ; Hatzenbuhler, NT; Evrard, DA; Harrison, BL; Magolda, R; Pangalos, MN; Schechter, LE; Rosenzweig-Lipson, S; Andree, TH

    2009-01-01

    Background and purpose As a combination of 5-HT selective reuptake inhibitor (SSRI) with 5-HT1A receptor antagonism may yield a rapidly acting antidepressant, WAY-211612, a compound with both SSRI and 5-HT1A receptor antagonist activities, was evaluated in preclinical models. Experimental approach Occupancy studies confirmed the mechanism of action of WAY-211612, while its in vivo profile was characterized in microdialysis and behavioural models. Key results WAY-211612 inhibited 5-HT reuptake (Ki = 1.5 nmol·L−1; KB = 17.7 nmol·L−1) and exhibited full 5-HT1A receptor antagonist activity (Ki = 1.2 nmol·L−1; KB = 6.3 nmol·L−1; Imax 100% in adenyl cyclase assays; KB = 19.8 nmol·L−1; Imax 100% in GTPγS). WAY-211612 (3 and 30 mg·kg−1, po) occupied 5-HT reuptake sites in rat prefrontal cortex (56.6% and 73.6% respectively) and hippocampus (52.2% and 78.5%), and 5-HT1A receptors in the prefrontal cortex (6.7% and 44.7%), hippocampus (8.3% and 48.6%) and dorsal raphe (15% and 83%). Acute or chronic treatment with WAY-211612 (3–30 mg·kg−1, po) raised levels of cortical 5-HT approximately twofold, as also observed with a combination of an SSRI (fluoxetine; 30 mg·kg−1, s.c.) and a 5-HT1A antagonist (WAY-100635; 0.3 mg·kg−1, s.c). WAY-211612 (3.3–30 mg·kg−1, s.c.) decreased aggressive behaviour in the resident-intruder model, while increasing the number of punished crossings (3–30 mg·kg−1, i.p. and 10–56 mg·kg−1, po) in the mouse four-plate model and decreased adjunctive drinking behaviour (56 mg·kg−1, i.p.) in the rat scheduled-induced polydipsia model. Conclusions and implications These findings suggest that WAY-211612 may represent a novel antidepressant. PMID:19338583

  3. 5-HT1B Autoreceptors limit the effects of selective serotonin re-uptake inhibitors in mouse hippocampus and frontal cortex.

    PubMed

    Malagié, I; Trillat, A C; Bourin, M; Jacquot, C; Hen, R; Gardier, A M

    2001-02-01

    We used knockout mice and receptor antagonist strategies to investigate the contribution of the serotonin (5-hydroxytryptamine, 5-HT) 1B receptor subtype in mediating the effects of selective serotonin re-uptake inhibitors (SSRIs). Using in vivo intracerebral microdialysis in awake mice, we show that a single systemic administration of paroxetine (1 or 5 mg/kg, i.p.) increased extracellular serotonin levels [5-HT]ext in the ventral hippocampus and frontal cortex of wild-type and mutant mice. However, in the ventral hippocampus, paroxetine at the two doses studied induced a larger increase in [5-HT]ext in knockout than in wild-type mice. In the frontal cortex, the effect of paroxetine was larger in mutants than in wild-type mice at the 1 mg/kg, but not at 5 mg/kg. In addition, either the absence of the 5-HT1B receptor or its blockade with the mixed 5-HT1B/1D receptor antagonist, GR 127935, potentiated the effect of a single administration of paroxetine on extracellular 5-HT levels more in the ventral hippocampus than in the frontal cortex. These data suggest that 5-HT1B autoreceptors limit the effects of SSRIs on dialysate 5-HT levels at serotonergic nerve terminals.

  4. 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

  5. Effects of repeated oral doses of dexnorfenfluramine on 5-HT levels and 5-HT uptake sites in rat brain.

    PubMed

    Gobbi, M; Bergami, A; Caltavuturo, C; Valle, F D; Mennini, T; Caccia, S

    1996-11-15

    The effects of oral dexnorfenfluramine (DNF; 1-4 mg/kg, twice daily for 4 days), the active metabolite of dexfenfluramine, were examined on rat regional brain indole contents and [3H]citalopram binding. Two hours after the last dose, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were dose-dependently lowered at doses above 1.5 mg/kg, with slight regional differences. Cortical 5-HT uptake sites were reduced only at the highest dose. Above 2 mg/kg DNF also caused a more lasting reduction (4 weeks) of regional indoles and cortical 5-HT uptake sites. At this longer time while the decrease in hippocampal 5-HT levels and cortical 5-HT uptake sites remained essentially constant, cortical and striatal 5-HT levels were lowered less than at 2 h, suggesting a return toward control values.

  6. Effect of acute and chronic tramadol on [3H]-5-HT uptake in rat cortical synaptosomes

    PubMed Central

    Giusti, Pietro; Buriani, Alessandro; Cima, Lorenzo; Lipartiti, Maria

    1997-01-01

    Tramadol hydrochloride is a centrally acting opioid analgesic, the efficacy and potency of which is only five to ten times lower than that of morphine. Opioid, as well as non-opioid mechanisms, may participate in the analgesic activity of tramadol. [3H]-5-hydroxytryptamine (5-HT) uptake in rat isolated cortical synaptosomes was studied in the presence of tramadol, desipramine, fluoxetine, methadone and morphine. Methadone and tramadol inhibited synaptosomal [3H]-5-HT uptake with apparent Kis of 0.27±0.04 and 0.76±0.04 μM, respectively. Morphine essentially failed to inhibit [3H]-5-HT uptake (Ki 0.50±0.30 M). Methadone, morphine and tramadol were active in the hot plate test with ED50s of 3.5, 4.3 and 31 mg kg−1, respectively. At the highest tested dose (80 mg kg−1) tramadol produced only 77±5.3% of the maximal possible effect. When [3H]-5-HT uptake was examined in synaptosomes prepared from rats 30 min after a single dose of morphine, methadone or tramadol, only tramadol (31 mg kg−1, s.c., equal to the ED50 in the hot plate test) and methadone (35 mg kg−1, s.c., equal to the ED90 in the hot plate test) decreased uptake. Animals were chronically treated for 15 days with increasing doses of tramadol or methadone (5 to 40 mg kg−1 and 15 to 120 mg kg−1, s.c., respectively). Twenty-four hours after the last drug injection, a challenge dose of methadone (35 mg kg−1, s.c.) or tramadol (31 mg kg−1, s.c.) was administered. [3H]-5-HT uptake was not affected in synaptosomes prepared from rats chronically-treated with methadone, whereas chronic tramadol was still able to reduce this parameter by 42%. Rats chronically-treated with methadone showed a significant increase in [3H]-5-HT uptake (190%) 72 h after drug withdrawal. In contrast, [3H]-5-HT uptake in rats chronically-treated with tramadol (110%) did not differ significantly from control animals. These results further support the hypothesis that [3H]-5-HT uptake

  7. [5-HT1B serotonin receptors and antidepressant effects of selective serotonin reuptake inhibitors ].

    PubMed

    Gardier, A M; Trillat, A C; Malagié, I; David, D; Hascoët, M; Colombel, M C; Jolliet, P; Jacquot, C; Hen, R; Bourin, M

    2001-05-01

    We used knockout mice and receptor antagonist strategies to investigate the contribution of the serotonin (5-hydroxytryptamine, 5-HT) 5-HT1B receptor subtype in mediating the effects of selective serotonin reuptake inhibitors (SSRIs). Using in vivo intracerebral microdialysis in awake mice, we show that a single systemic administration of paroxetine (1 or 5 mg/kg, i.p.) increased extracellular serotonin levels [5-HT]ext in the ventral hippocampus and frontal cortex of wild-type and mutant mice. However, in the ventral hippocampus, paroxetine at the two doses studied induced a larger increase in [5-HT]ext in knockout than in wild-type mice. In the frontal cortex, the effect of paroxetine was larger in mutants than in wild-type mice at the 1 mg/kg dose but not at 5 mg/kg. In addition, either the absence of the 5-HT1B receptor or its blockade with the mixed 5-HT1B/1D receptor antagonist, GR 127935, potentiates the effect of a single administration of paroxetine on [5-HT]ext more in the ventral hippocampus than in the frontal cortex. Furthermore, we demonstrate that SSRIs decrease immobility in the forced swimming test; this effect is absent in 5-HT1B knockout mice and blocked by GR 127935 in wild-type suggesting therefore that activation of 5-HT1B receptors mediate the antidepressant-like effects of SSRIs. Taken together these data demonstrate that 5-HT1B autoreceptors appear to limit the effects of SSRI on dialysate 5-HT levels particularly in the hippocampus while presynaptic 5-HT1B heteroreceptors are likely to be required for the antidepressant activity of SSRIs.

  8. 3D QSAR based design of novel oxindole derivative as 5HT7 inhibitors.

    PubMed

    Chitta, Aparna; Sivan, Sree Kanth; Manga, Vijjulatha

    2014-06-01

    To understand the structural requirements of 5-hydroxytryptamine (5HT7) receptor inhibitors and to design new ligands against 5HT7 receptor with enhanced inhibitory potency, a three-dimensional quantitative structure-activity relationship study with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) for a data set of 56 molecules consisting of oxindole, tetrahydronaphthalene, aryl ketone substituted arylpiperazinealkylamide derivatives was performed. Derived model showed good statistical reliability in terms of predicting 5HT7 inhibitory activity of the molecules, based on molecular property fields like steric, electrostatic, hydrophobic, hydrogen bond donor and hydrogen bond acceptor fields. This is evident from statistical parameters like conventional r2 and a cross validated (q2) values of 0.985, 0.743 for CoMFA and 0.970, 0.608 for CoMSIA, respectively. Predictive ability of the models to determine 5HT7 antagonistic activity is validated using a test set of 16 molecules that were not included in the training set. Predictive r2 obtained for the test set was 0.560 and 0.619 for CoMFA and CoMSIA, respectively. Steric, electrostatic fields majorly contributed toward activity which forms the basis for design of new molecules. Absorption, distribution, metabolism and elimination (ADME) calculation using QikProp 2.5 (Schrodinger 2010, Portland, OR) reveals that the molecules confer to Lipinski's rule of five in majority of the cases.

  9. Electrophysiological evidence for rapid 5-HT₁A autoreceptor inhibition by vilazodone, a 5-HT₁A receptor partial agonist and 5-HT reuptake inhibitor.

    PubMed

    Ashby, Charles R; Kehne, John H; Bartoszyk, Gerd D; Renda, Matthew J; Athanasiou, Maria; Pierz, Kerri A; Seyfried, Christoph A

    2013-08-15

    This study examined the effect of vilazodone, a combined serotonin (5-HT) reuptake inhibitor and 5-HT(1A) receptor partial agonist, paroxetine and fluoxetine on the sensitivity of 5-HT(1A) autoreceptors of serotonergic dorsal raphe nucleus neurons in rats. These effects were assessed by determining the intravenous dose of (±)-8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) required to suppress the basal firing rate of these neurons by 50% (ID₅₀) in anesthetized rats using in vivo electrophysiology. 5-HT uptake inhibition was determined by the ability of the compounds to reverse (±)-p-chloroamphetamine (PCA)-induced rat hypothalamic 5-HT depletion ex vivo. Acute vilazodone administration (0.63 and 2.1 µmol/kg, s.c.), compared with vehicle, significantly increased (2-3-fold) the ID₅₀ of 8-OH-DPAT at 4 h, but not 24h after administration. Subchronic administration (3 days) significantly increased the ID₅₀ value at 4 h (3-4-fold) and at 24 h (~2-fold). In contrast, paroxetine and fluoxetine at doses that were supramaximal for 5-HT uptake inhibition did not significantly alter the ID₅₀ value of 8-OH-DPAT after acute or subchronic administration. Vilazodone antagonized the action of PCA 3.5 h and 5 h after a single dose (ID₅₀ 1.49 and 0.46 µmol/kg, s.c., respectively), but was inactive 18 h post-administration, corroborating the electrophysiological results at 24 h following acute administration. The results are consistent with the concept of rapid and, following repeated treatment, prolonged inhibition of 5-HT(1A) autoreceptors by vilazodone. This effect could occur by either direct interaction with, or desensitization of, these receptors, an effect which cannot be ascribed to vilazodone's 5-HT reuptake inhibiting properties. PMID:23872377

  10. Electrophysiological evidence for rapid 5-HT₁A autoreceptor inhibition by vilazodone, a 5-HT₁A receptor partial agonist and 5-HT reuptake inhibitor.

    PubMed

    Ashby, Charles R; Kehne, John H; Bartoszyk, Gerd D; Renda, Matthew J; Athanasiou, Maria; Pierz, Kerri A; Seyfried, Christoph A

    2013-08-15

    This study examined the effect of vilazodone, a combined serotonin (5-HT) reuptake inhibitor and 5-HT(1A) receptor partial agonist, paroxetine and fluoxetine on the sensitivity of 5-HT(1A) autoreceptors of serotonergic dorsal raphe nucleus neurons in rats. These effects were assessed by determining the intravenous dose of (±)-8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) required to suppress the basal firing rate of these neurons by 50% (ID₅₀) in anesthetized rats using in vivo electrophysiology. 5-HT uptake inhibition was determined by the ability of the compounds to reverse (±)-p-chloroamphetamine (PCA)-induced rat hypothalamic 5-HT depletion ex vivo. Acute vilazodone administration (0.63 and 2.1 µmol/kg, s.c.), compared with vehicle, significantly increased (2-3-fold) the ID₅₀ of 8-OH-DPAT at 4 h, but not 24h after administration. Subchronic administration (3 days) significantly increased the ID₅₀ value at 4 h (3-4-fold) and at 24 h (~2-fold). In contrast, paroxetine and fluoxetine at doses that were supramaximal for 5-HT uptake inhibition did not significantly alter the ID₅₀ value of 8-OH-DPAT after acute or subchronic administration. Vilazodone antagonized the action of PCA 3.5 h and 5 h after a single dose (ID₅₀ 1.49 and 0.46 µmol/kg, s.c., respectively), but was inactive 18 h post-administration, corroborating the electrophysiological results at 24 h following acute administration. The results are consistent with the concept of rapid and, following repeated treatment, prolonged inhibition of 5-HT(1A) autoreceptors by vilazodone. This effect could occur by either direct interaction with, or desensitization of, these receptors, an effect which cannot be ascribed to vilazodone's 5-HT reuptake inhibiting properties.

  11. [Homozygote mice deficient in serotonin 5-HT1B receptor and antidepressant effect of selective serotonin reuptake inhibitors].

    PubMed

    Trillat, A C; Malagié, I; Bourin, M; Jacquot, C; Hen, R; Gardier, A M

    1998-01-01

    We use the knockout mice strategy to investigate the contribution of the 5-HT1B receptor in mediating the effects of selective serotonin reuptake inhibitors (SSRI). Using microdialysis in awake 129/Sv mice, we show that the absence of the 5-HT1B receptor in mutant mice (KO 1B -/-) potentiated the effect of paroxetine on extracellular 5-HT levels in the ventral hippocampus, but not in the frontal cortex compared to wild-type mice (WT). Furthermore, using the forced swimming test, we demonstrate that SSRIs decreased immobility of WT mice, and this effect is absent in KO 1B -/- mice showing therefore that activation of 5-HT1B receptors mediate the antidepressant-like effects of SSRIs. Taken together these findings suggest that 5-HT1B autoreceptors limit the effects of SSRI particularly in the hippocampus while postsynaptic 5-HT1B receptors are required for the antidepressant activity of SSRIs.

  12. Design of novel quinazolinone derivatives as inhibitors for 5HT7 receptor.

    PubMed

    Chitta, Aparna; Jatavath, Mohan Babu; Fatima, Sabiha; Manga, Vijjulatha

    2012-02-01

    To study the pharmacophore properties of quinazolinone derivatives as 5HT(7) inhibitors, 3D QSAR methodologies, namely Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) were applied, partial least square (PLS) analysis was performed and QSAR models were generated. The derived model showed good statistical reliability in terms of predicting the 5HT(7) inhibitory activity of the quinazolione derivative, based on molecular property fields like steric, electrostatic, hydrophobic, hydrogen bond donor and hydrogen bond acceptor fields. This is evident from statistical parameters like q(2) (cross validated correlation coefficient) of 0.642, 0.602 and r(2) (conventional correlation coefficient) of 0.937, 0.908 for CoMFA and CoMSIA respectively. The predictive ability of the models to determine 5HT(7) antagonistic activity is validated using a test set of 26 molecules that were not included in the training set and the predictive r(2) obtained for the test set was 0.512 & 0.541. Further, the results of the derived model are illustrated by means of contour maps, which give an insight into the interaction of the drug with the receptor. The molecular fields so obtained served as the basis for the design of twenty new ligands. In addition, ADME (Adsorption, Distribution, Metabolism and Elimination) have been calculated in order to predict the relevant pharmaceutical properties, and the results are in conformity with required drug like properties.

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

    PubMed

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

    2016-05-27

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

  14. Exercise performance is not influenced by a 5-HT reuptake inhibitor.

    PubMed

    Meeusen, R; Piacentini, M F; Van Den Eynde, S; Magnus, L; De Meirleir, K

    2001-07-01

    The purpose of the present study was to examine the effect of a selective serotonin (5-HT) reuptake inhibitor (SSRI) on exercise performance during a 90 min time trial. Eight well trained male cyclists (VO2max 68.1 +/- 9.5 ml/kg/min) performed three 90 min time trials at 65% Wattmax. Blood samples were collected via an indwelling venous catheter for adrenocorticotropin hormone (ACTH), prolactin (PRL), cortisol, catecholamines, growth hormone (GH) and beta-endorphins. The evening before and the morning of the time trials, the subjects ingested a capsule containing either placebo (lactose) or 20 mg Fluoxetine-HCI (Prozac, Ely Lilly Belgium). A double blind, randomized, placebo controlled, cross-over design was performed. Performance was not influenced by the SSRI. As expected, all blood parameters increased significantly during exercise (p < 0.05). During the SSRI trial most parameters were slightly lower but only significantly for endorphins and PRL (p < 0.05). The results demonstrate that performance is not influenced by an SSRI, although some plasma hormones indicate a central effect of the drug. Surprisingly, the increases in PRL and endorphins were lower during the SSRI trial, meaning that the hormonal modulation during exercise might be regulated by the interaction between neurotransmitters rather than by serotonin alone. PMID:11510868

  15. Role of CCK in anti-exploratory action of paroxetine, 5-HT reuptake inhibitor.

    PubMed

    Kõks, Sulev; Bourin, Michel; Võikar, Vootele; Soosaar, Andres; Vasar, Eero

    1999-03-01

    The administration of paroxetine (0.5-8 mg/kg), a selective 5-HT reuptake inhibitor, induced a dose-dependent reduction of exploratory activity of rats in the motility test. In the elevated plus-maze paroxetine was less effective, only 8 mg/kg of paroxetine decreased the exploratory behaviour of rats. The doses of paroxetine (2-8 mg/kg) reducing the exploratory activity in the motility test increased the density of CCK receptors in the frontal cortex, but not in the hippocampus. The treatment of rats with the CCK(B) receptor antagonist LY288,513 (0.01-1 mg/kg) did not change the exploratory activity. However, the reduction of exploratory activity induced by the low dose of paroxetine (2 mg/kg), but not by the higher dose (8 mg/kg), was dose-dependently reversed by the administration of LY288,513. Moreover, LY288,513 did not affect the anti-exploratory action of paroxetine (8 mg/kg) in the elevated plus-maze. Diazepam at doses (0.5-1.0 mg/kg) not suppressing the locomotor activity did not change the anti-exploratory action of paroxetine in the motility test. It is likely that the anti-exploratory action of a low dose of paroxetine (2 mg/kg) is not related to the increase in anxiety, but rather to the reduction of exploratory drive. Evidence exists that this effect of paroxetine is mediated via the activation of CCK-ergic transmission.

  16. Platelet uptake of serotonin (5-HT) during ethanol withdrawal in male alcoholics

    SciTech Connect

    Neiman, J.; Beving, H.; Malmgren, R.

    1987-06-15

    Changes in the kinetic variables of the platelet serotonin uptake, Km and Vmax, were studied in 7 male alcoholics, admitted for detoxification and in sex- and age-matched volunteers. On admission the alcoholics had lower Km values than reference subjects (p less than 0.05). During detoxification the Km values normalized. Vmax was normal throughout the study in spite of the changes in platelet count. The results of the study suggest that the affinity of serotonin to its uptake receptor is transiently increased after a period of heavy drinking.

  17. GDM-associated insulin deficiency hinders the dissociation of SERT from ERp44 and down-regulates placental 5-HT uptake

    PubMed Central

    Li, Yicong; Hadden, Coedy; Singh, Preeti; Mercado, Charles P.; Murphy, Pamela; Dajani, Nafisa K.; Lowery, Curtis L.; Roberts, Drucilla J.; Maroteaux, Luc; Kilic, Fusun

    2014-01-01

    Serotonin (5-HT) transporter (SERT) regulates the level of 5-HT in placenta. Initially, we found that in gestational diabetes mellitus (GDM), whereas free plasma 5-HT levels were elevated, the 5-HT uptake rates of trophoblast were significantly down-regulated, due to impairment in the translocation of SERT molecules to the cell surface. We sought to determine the factors mediating the down-regulation of SERT in GDM trophoblast. We previously reported that an endoplasmic reticulum chaperone, ERp44, binds to Cys200 and Cys209 residues of SERT to build a disulfide bond. Following this posttranslational modification, before trafficking to the plasma membrane, SERT must be dissociated from ERp44; and this process is facilitated by insulin signaling and reversed by the insulin receptor blocker AGL2263. However, the GDM-associated defect in insulin signaling hampers the dissociation of ERp44 from SERT. Furthermore, whereas ERp44 constitutively occupies Cys200/Cys209 residues, one of the SERT glycosylation sites, Asp208 located between the two Cys residues, cannot undergo proper glycosylation, which plays an important role in the uptake efficiency of SERT. Herein, we show that the decrease in 5-HT uptake rates of GDM trophoblast is the consequence of defective insulin signaling, which entraps SERT with ERp44 and impairs its glycosylation. In this regard, restoring the normal expression of SERT on the trophoblast surface may represent a novel approach to alleviating some GDM-associated complications. PMID:25512553

  18. The tryptophan hydroxylase activation inhibitor, AGN-2979, decreases regional 5-HT synthesis in the rat brain measured with alpha-[14C]methyl-L-tryptophan: an autoradiographic study.

    PubMed

    Hasegawa, Shu; Kanemaru, Kazuya; Gittos, Maurice; Diksic, Mirko

    2005-10-15

    Many experimental conditions are stressful for animals. It is well known that stress induces tryptophan hydroxylase (TPH) activation, resulting in increased serotonin (5-HT) synthesis. In our experimental procedure to measure 5-HT synthesis using alpha-[(14)C]methyl-L-tryptophan (alpha-MTrp) autoradiographic method, the hind limbs of animals are restrained using a loose-fitted plaster cast such that the forelimbs of the animal remain free. The objective of the present investigation was to evaluate the changes, if any, in 5-HT synthesis, after injecting these restrained rats with the TPH activation inhibitor AGN-2979. The effect on regional 5-HT synthesis was studied using the alpha-MTrp autoradiographic method. The hypothesis was that the TPH activation inhibitor would reduce 5-HT synthesis, if TPH activation was induced by this restraint. The rats received injection of AGN-2979 (10 mg/kg, i.p.) or distilled water vehicle (1 mL/kg, i.p.) 1 h prior to tracer administration. The free- and total tryptophan concentrations were not significantly different between the treatment and control groups. The results demonstrate that 5-HT synthesis in AGN-2979 treated rats is significantly decreased (-12 to -35%) in both the raphe nuclei and their terminal areas when compared to the control rats. These findings suggest that restrained conditions, such as those used in our experimental protocol, induce TPH activation resulting in an increased 5-HT synthesis throughout the brain. The reduction in 5-HT synthesis in the AGN-2979 group is not related to a change in the plasma tryptophan. Because there was no activation in the pineal body, the structure having a different isoform of TPH, we can propose that it is only the brain TPH that becomes activated with this specific restraint.

  19. A Divergent SAR Study Allows Optimization of a Potent 5-HT2c Inhibitor to a Promising Antimalarial Scaffold

    PubMed Central

    2012-01-01

    From the 13 533 chemical structures published by GlaxoSmithKline in 2010, we identified 47 quality starting points for lead optimization. One of the most promising hits was the TCMDC-139046, a molecule presenting an indoline core, which is well-known for its anxiolytic properties by interacting with serotonin antagonist receptors 5-HT2. The inhibition of this target will complicate the clinical development of these compounds as antimalarials. Herein, we present the antimalarial profile of this series and our efforts to avoid interaction with this receptor, while maintaining a good antiparasitic potency. By using a double-divergent structure–activity relationship analysis, we have obtained a novel lead compound harboring an indoline core. PMID:24900481

  20. Effects of chronic paroxetine treatment on dialysate serotonin in 5-HT1B receptor knockout mice.

    PubMed

    Gardier, A M; David, D J; Jego, G; Przybylski, C; Jacquot, C; Durier, S; Gruwez, B; Douvier, E; Beauverie, P; Poisson, N; Hen, R; Bourin, M

    2003-07-01

    The role of serotonin (5-HT)1B receptors in the mechanism of action of selective serotonin re-uptake inhibitors (SSRI) was studied by using intracerebral in vivo microdialysis in conscious, freely moving wild-type and 5-HT1B receptor knockout (KO 5-HT1B) mice in order to compare the effects of chronic administration of paroxetine via osmotic minipumps (1 mg per kg per day for 14 days) on extracellular 5-HT levels ([5-HT]ext) in the medial prefrontal cortex and ventral hippocampus. Basal [5-HT]ext values in the medial prefrontal cortex and ventral hippocampus, approximately 20 h after removing the minipump, were not altered by chronic paroxetine treatment in both genotypes. On day 15, in the ventral hippocampus, an acute paroxetine challenge (1 mg/kg i.p.) induced a larger increase in [5-HT]ext in saline-pretreated mutant than in wild-type mice. This difference between the two genotypes in the effect of the paroxetine challenge persisted following chronic paroxetine treatment. Conversely, in the medial prefrontal cortex, the paroxetine challenge increased [5-HT]ext similarly in saline-pretreated mice of both genotypes. Such a challenge produced a further increase in cortical [5-HT]ext compared with that in saline-pretreated groups of both genotypes, but no differences were found between genotypes following chronic treatment. To avoid the interaction with raphe 5-HT1A autoreceptors, 1 micro m paroxetine was perfused locally through the dialysis probe implanted in the ventral hippocampus; similar increases in hippocampal [5-HT]ext were found in acutely or chronically treated wild-type mice. Systemic administration of the mixed 5-HT1B/1D receptor antagonist GR 127935 (4 mg/kg) in chronically treated wild-type mice potentiated the effect of a paroxetine challenge dose on [5-HT]ext in the ventral hippocampus, whereas systemic administration of the selective 5-HT1A receptor antagonist WAY 100635 did not. By using the zero net flux method of quantitative microdialysis in

  1. Serotonin 5-HT2 Receptor Interactions with Dopamine Function: Implications for Therapeutics in Cocaine Use Disorder

    PubMed Central

    Cunningham, Kathryn A.

    2015-01-01

    Cocaine exhibits prominent abuse liability, and chronic abuse can result in cocaine use disorder with significant morbidity. Major advances have been made in delineating neurobiological mechanisms of cocaine abuse; however, effective medications to treat cocaine use disorder remain to be discovered. The present review will focus on the role of serotonin (5-HT; 5-hydroxytryptamine) neurotransmission in the neuropharmacology of cocaine and related abused stimulants. Extensive research suggests that the primary contribution of 5-HT to cocaine addiction is a consequence of interactions with dopamine (DA) neurotransmission. The literature on the neurobiological and behavioral effects of cocaine is well developed, so the focus of the review will be on cocaine with inferences made about other monoamine uptake inhibitors and releasers based on mechanistic considerations. 5-HT receptors are widely expressed throughout the brain, and several different 5-HT receptor subtypes have been implicated in mediating the effects of endogenous 5-HT on DA. However, the 5-HT2A and 5-HT2C receptors in particular have been implicated as likely candidates for mediating the influence of 5-HT in cocaine abuse as well as to traits (e.g., impulsivity) that contribute to the development of cocaine use disorder and relapse in humans. Lastly, new approaches are proposed to guide targeted development of serotonergic ligands for the treatment of cocaine use disorder. PMID:25505168

  2. Serotonin 5-HT2 receptor interactions with dopamine function: implications for therapeutics in cocaine use disorder.

    PubMed

    Howell, Leonard L; Cunningham, Kathryn A

    2015-01-01

    Cocaine exhibits prominent abuse liability, and chronic abuse can result in cocaine use disorder with significant morbidity. Major advances have been made in delineating neurobiological mechanisms of cocaine abuse; however, effective medications to treat cocaine use disorder remain to be discovered. The present review will focus on the role of serotonin (5-HT; 5-hydroxytryptamine) neurotransmission in the neuropharmacology of cocaine and related abused stimulants. Extensive research suggests that the primary contribution of 5-HT to cocaine addiction is a consequence of interactions with dopamine (DA) neurotransmission. The literature on the neurobiological and behavioral effects of cocaine is well developed, so the focus of the review will be on cocaine with inferences made about other monoamine uptake inhibitors and releasers based on mechanistic considerations. 5-HT receptors are widely expressed throughout the brain, and several different 5-HT receptor subtypes have been implicated in mediating the effects of endogenous 5-HT on DA. However, the 5-HT2A and 5-HT2C receptors in particular have been implicated as likely candidates for mediating the influence of 5-HT in cocaine abuse as well as to traits (e.g., impulsivity) that contribute to the development of cocaine use disorder and relapse in humans. Lastly, new approaches are proposed to guide targeted development of serotonergic ligands for the treatment of cocaine use disorder. PMID:25505168

  3. [Behavioral pharmacological properties of the novel antidepressant paroxetine, a selective 5-HT uptake inhibitor].

    PubMed

    Yamamoto, T; Shibata, S; Shimazoe, T; Iwasaki, K; Ohno, M; Minamoto, Y; Furuya, Y; Miyamoto, K; Watanabe, S; Ueki, S

    1989-09-01

    The behavioral effects of paroxetine were investigated in mice and rats in comparison with imipramine and amitriptyline. 1) Locomotor activities were decreased by imipramine and amitriptyline but not by paroxetine in both animal species. 2) Paroxetine antagonized methamphetamine-induced hyperactivity in mice as did imipramine and amitriptyline. 3) Paroxetine showed a more potent antimuricidal effect in raphe-lesioned rats than imipramine and amitriptyline, and it also inhibited muricide in olfactory bulbectomized rats. 4) The immobility of rats in the forced swimming test was markedly decreased by imipramine and amitriptyline, but only slightly by paroxetine. 5) Like imipramine and amitriptyline, paroxetine potentiated the methamphetamine- or L-DOPA-induced stereotyped sniffing, and it inhibited oxotremorine-induced tremor. 6) Paroxetine antagonized reserpine-induced hypothermia, tetrabenazine-induced ptosis, and enhanced ether-induced anesthesia, all less potently than imipramine and amitriptyline. 7) The analgesic action of paroxetine was stronger than that of imipramine and amitriptyline. 8) Paroxetine did not antagonize maximal electroshock- or pentetrazol-induced convulsions and haloperidol- or THC-induced catalepsy in rats. In addition, paroxetine neither exerted muscle relaxation nor affected the shuttle-box type conditioned avoidance in rats. From these results, the behavioral effects of paroxetine, as compared with imipramine and amitriptyline, were characterized by its potent antimuricidal action in raphe-lesioned rats and its weak effect in the forced swimming test and by its less potent muscle relaxant, anticonvulsant, anticataleptic and anesthesia-potentiating actions.

  4. Comparative potencies of 3,4-methylenedioxymethamphetamine (MDMA) analogues as inhibitors of [3H]noradrenaline and [3H]5-HT transport in mammalian cell lines

    PubMed Central

    Montgomery, T; Buon, C; Eibauer, S; Guiry, P J; Keenan, A K; McBean, G J

    2007-01-01

    Background and purpose: Illegal ‘ecstasy' tablets frequently contain 3,4-methylenedioxymethamphetamine (MDMA)-like compounds of unknown pharmacological activity. Since monoamine transporters are one of the primary targets of MDMA action in the brain, a number of MDMA analogues have been tested for their ability to inhibit [3H]noradrenaline uptake into rat PC12 cells expressing the noradrenaline transporter (NET) and [3H]5-HT uptake into HEK293 cells stably transfected with the 5-HT transporter (SERT). Experimental approach: Concentration–response curves for the following compounds at both NET and SERT were determined under saturating substrate conditions: 4-hydroxy-3-methoxyamphetamine (HMA), 4-hydroxy-3-methoxymethamphetamine (HMMA), 3,4-methylenedioxy-N-hydroxyamphetamine (MDOH), 2,5-dimethoxy-4-bromophenylethylamine (2CB), 3,4-dimethoxymethamphetamine (DMMA), 3,4-methylenedioxyphenyl-2-butanamine (BDB), 3,4-methylenedioxyphenyl-N-methyl-2-butanamine (MBDB) and 2,3-methylenedioxymethamphetamine (2,3-MDMA). Key results: 2,3-MDMA was significantly less potent than MDMA at SERT, but equipotent with MDMA at NET. 2CB and BDB were both significantly less potent than MDMA at NET, but equipotent with MDMA at SERT. MBDB, DMMA, MDOH and the MDMA metabolites HMA and HMMA, were all significantly less potent than MDMA at both NET and SERT. Conclusions and implications: This study provides an important insight into the structural requirements of MDMA analogue affinity at both NET and SERT. It is anticipated that these results will facilitate understanding of the likely pharmacological actions of structural analogues of MDMA. PMID:17891159

  5. Functional expression of 5-HT{sub 2A} receptor in osteoblastic MC3T3-E1 cells

    SciTech Connect

    Hirai, Takao; Kaneshige, Kota; Kurosaki, Teruko; Nishio, Hiroaki

    2010-05-28

    In the previous study, we reported the gene expression for proteins related to the function of 5-hydroxytryptamine (5-HT, serotonin) and elucidated the expression patterns of 5-HT{sub 2} receptor subtypes in mouse osteoblasts. In the present study, we evaluated the possible involvement of 5-HT receptor subtypes and its inactivation system in MC3T3-E1 cells, an osteoblast cell line. DOI, a 5-HT{sub 2A} and 5-HT{sub 2C} receptor selective agonist, as well as 5-HT concentration-dependently increased proliferative activities of MC3T3-E1 cells in their premature period. This effect of 5-HT on cell proliferation were inhibited by ketanserin, a 5-HT{sub 2A} receptor specific antagonist. Moreover, both DOI-induced cell proliferation and phosphorylation of ERK1 and 2 proteins were inhibited by PD98059 and U0126, selective inhibitors of MEK in a concentration-dependent manner. Furthermore, treatment with fluoxetine, a 5-HT specific re-uptake inhibitor which inactivate the function of extracellular 5-HT, significantly increased the proliferative activities of MC3T3-E1 cells in a concentration-dependent manner. Our data indicate that 5-HT fill the role for proliferation of osteoblast cells in their premature period. Notably, 5-HT{sub 2A} receptor may be functionally expressed to regulate mechanisms underlying osteoblast cell proliferation, at least in part, through activation of ERK/MAPK pathways in MC3T3-E1 cells.

  6. 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.

  7. SB-649915-B, a novel 5-HT1A/B autoreceptor antagonist and serotonin reuptake inhibitor, is anxiolytic and displays fast onset activity in the rat high light social interaction test.

    PubMed

    Starr, Kathryn R; Price, Gary W; Watson, Jeannette M; Atkinson, Peter J; Arban, Roberto; Melotto, Sergio; Dawson, Lee A; Hagan, Jim J; Upton, Neil; Duxon, Mark S

    2007-10-01

    Preclinically, the combination of an SSRI and 5-HT autoreceptor antagonist has been shown to reduce the time to onset of anxiolytic activity compared to an SSRI alone. In accordance with this, clinical data suggest the coadministration of an SSRI and (+/-) pindolol can decrease the time to onset of anxiolytic/antidepressant activity. Thus, the dual-acting novel SSRI and 5-HT(1A/B) receptor antagonist, SB-649915-B, has been assessed in acute and chronic preclinical models of anxiolysis. SB-649915-B (0.1-1.0 mg/kg, i.p.) significantly reduced ultrasonic vocalization in male rat pups separated from their mothers (ED(50) of 0.17 mg/kg). In the marmoset human threat test SB-649915-B (3.0 and 10 mg/kg, s.c.) significantly reduced the number of postures with no effect on locomotion. In the rat high light social interaction (SI), SB-649915-B (1.0-7.5 mg/kg, t.i.d.) and paroxetine (3.0 mg/kg, once daily) were orally administered for 4, 7, and 21 days. Ex vivo inhibition of [(3)H]5-HT uptake was also measured following SI. SB-649915-B and paroxetine had no effect on SI after 4 days. In contrast to paroxetine, SB-649915-B (1.0 and 3.0 mg/kg, p.o., t.i.d.) significantly (p<0.05) increased SI time with no effect on locomotion, indicative of an anxiolytic-like profile on day 7. Anxiolysis was maintained after chronic (21 days) administration by which time paroxetine also increased SI significantly. 5-HT uptake was inhibited by SB-649915-B at all time points to a similar magnitude as that seen with paroxetine. In conclusion, SB-649915-B is acutely anxiolytic and reduces the latency to onset of anxiolytic behavior compared to paroxetine in the SI model.

  8. The 5-HT{sub 2A} serotoninergic receptor is expressed in the MCF-7 human breast cancer cell line and reveals a mitogenic effect of serotonin

    SciTech Connect

    Sonier, Brigitte; Arseneault, Madeleine; Lavigne, Carole; Ouellette, Rodney J.; Vaillancourt, Cathy . E-mail: cathy.vaillancourt@iaf.inrs.ca

    2006-05-19

    Serotonin (5-hydroxytryptamine, 5-HT) has been described as a mitogen in a variety of cell types and carcinomas. It exerts its mitogenic effect by interacting with a wide range of 5-HT receptor types. Certain studies suggest that some selective serotonin re-uptake inhibitors promote breast cancer in animals and humans. This study attempts to clarify the role of serotonin in promoting the growth of neoplastic mammary cells. Expression of the 5-HT{sub 2A} serotoninergic receptor subtype in MCF-7 cells was determined by RT-PCR, Western blotting, and immunofluorescence analysis. The mitogenic effect of 5-HT on MCF-7 cells was determined by means of the MTT proliferation assay. We have demonstrated that the 5-HT{sub 2A} receptor subtype is fully expressed in the MCF-7 human breast cancer cell line, in terms of encoding mRNA and receptor protein. Automated sequencing has confirmed that the 5-HT{sub 2A} receptor present in this cell line is identical to the 5-HT{sub 2A} receptor found in human platelets and in human cerebral cortex. Furthermore, this receptor was found by immunofluorescence to be on the plasma membrane. MTT proliferation assays revealed that 5-HT and DOI, a selective 5-HT{sub 2A} receptor subtype agonist, stimulated MCF-7 cell. These results indicate that 5-HT plays a mitogenic role in neoplastic mammary cells. Our data also indicate that 5-HT exerts this positive growth effect on MCF-7 cells through, in part, the 5-HT{sub 2A} receptor subtype, which is fully expressed in this cell line.

  9. 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.

  10. The role of 5-HT1A and 5-HT1B receptors in antidepressant drug actions in the mouse forced swimming test.

    PubMed

    Redrobe, J P; MacSweeney, C P; Bourin, M

    1996-12-30

    The forced swimming test is a behavioural model developed to predict the efficacy of antidepressant drugs. Few studies have been aimed at evaluating the mechanism of action of antidepressants in the forced swimming test. The present study was designed in order to further evaluate the mode of action of antidepressants in the forced swimming test, by using selective agonists and antagonists at 5-HT1A and 5-HT1B receptor sites. Agonists/antagonists and antidepressants were administered 45 min and 30 min, respectively, prior to testing. Prior administration of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (1 mg/kg, i.p.) induced anti-immobility effects with the tricyclic antidepressant imipramine (8 mg/kg, i.p.) and noradrenaline uptake inhibitors maprotiline (8 mg/kg, i.p.) and desipramine (16 mg/kg, i.p.), but not with fluoxetine (16 mg/kg, i.p.), citalopram (16 mg/kg, i.p.) or fluvoxamine (8 mg/kg, i.p.). These effects were antagonised by prior administration of 1-(2-methoxyphenyl)-4-[-(2-phthalimido)butyl]piperazine) (NAN 190) (0.5 mg/kg, i.p.). On the other hand, pretreatment with (+/-)-pindolol (32 mg/kg, i.p.) potentiated the effects of the selective serotonin reuptake inhibitors and was devoid of any activity with imipramine (8 mg/kg, i.p.), maprotiline (8 mg/kg, i.p.) or desipramine (16 mg/kg, i.p.). Prior administration of 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridyl)-1H-indole (RU 24969) enhanced the antidepressant-like effects of the selective serotonin reuptake inhibitors and imipramine (8 mg/kg, i.p.) in the forced swimming test. The anti-immobility effects of the selective serotonin reuptake inhibitors in the forced swimming test seem to be mediated by presynaptic 5-HT1A receptors as well as postsynaptic 5-HT1B receptors. Antidepressant-like effects of the noradrenaline uptake inhibitors seem, on the other hand, to be mediated by postsynaptic 5-HT1A receptors. Considering the variety of 5-HT receptors, it is possible that other subtypes may participate

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

    PubMed Central

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

    2012-01-01

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

  12. Serotonin increases ERK1/2 phosphorylation in astrocytes by stimulation of 5-HT2B and 5-HT2C receptors.

    PubMed

    Li, Baoman; Zhang, Shiquen; Li, Min; Hertz, Leif; Peng, Liang

    2010-11-01

    We have previously shown that fluoxetine causes ERK(1/2) phosphorylation in cultured mouse astrocytes mediated exclusively by stimulation of 5-HT(2B) receptors (Li et al., 2008b). This raises the question whether this is also the case for serotonin (5-HT) itself. In the present study serotonin was found to induce ERK(1/2) phosphorylation by stimulation of 5-HT(2B) receptors with high affinity (EC(50): 20-30 pM), and by stimulation of 5-HT(2C) receptor with low affinity (EC(50): 1 microM or higher). ERK(1/2) phosphorylation induced by stimulation of either 5-HT(2B) or 5-HT(2C) receptors was mediated by epidermal growth factor (EGF) receptor transactivation (Peng et al., this issue), shown by the inhibitory effect of AG1478, an inhibitor of the EGF receptor tyrosine kinase, and GM6001, an inhibitor of Zn-dependent metalloproteinases, and thus of 5-HT(2B) receptor-mediated EGF receptor agonist release. It is discussed that the high potency of the 5-HT(2B)-mediated effect is consistent with literature data for binding affinity of serotonin to cloned human 5-HT(2B) receptors and with observations of low extracellular concentrations of serotonin in brain, which would allow a demonstrated moderate and modality-dependent increase in specific brain areas to activate 5-HT(2B) receptors. In contrast the relevance of the observed 5-HT(2C) receptors on astrocytes is questioned.

  13. Agonist- and antagonist-induced up-regulation of surface 5-HT3A receptors

    PubMed Central

    Morton, Russell A; Baptista-Hon, Daniel T; Hales, Tim G; Lovinger, David M

    2015-01-01

    Background and Purpose The 5-HT3 receptor is a member of the pentameric ligand-gated ion channel family and is pharmacologically targeted to treat irritable bowel syndrome and nausea/emesis. Furthermore, many antidepressants elevate extracellular concentrations of 5-HT. This study investigates the functional consequences of exposure of recombinant 5-HT3A receptors to agonists and antagonists. Experimental Approach We used HEK cells stably expressing recombinant 5-HT3A receptors and the ND7/23 (mouse neuroblastoma/dorsal root ganglion hybrid) cell line, which expresses endogenous 5-HT3 receptors. Surface expression of recombinant 5-HT3A receptors, modified to contain the bungarotoxin (BTX) binding sequence, was quantified using fluorescence microscopy to image BTX-conjugated fluorophores. Whole cell voltage-clamp electrophysiology was used to measure the density of current mediated by 5-HT3A receptors. Key Results 5-HT3A receptors were up-regulated by the prolonged presence of agonists (5-HT and m-chlorophenylbiguanide) and antagonists (MDL-72222 and morphine). The up-regulation of 5-HT3A receptors by 5-HT and MDL-72222 was time- and concentration-dependent but was independent of newly translated receptors. The phenomenon was observed for recombinant rodent and human 5-HT3A receptors and for endogenous 5-HT3 receptors in neuronal ND7/23 cells. Conclusions and Implications Up-regulation of 5-HT3A receptors, following exposure to either agonists or antagonists suggests that this phenomenon may occur in response to different therapeutic agents. Medications that elevate 5-HT levels, such as the antidepressant inhibitors of 5-HT reuptake and antiemetic inhibitors of 5-HT3 receptor function, may both raise receptor expression. However, this will require further investigation in vivo. PMID:25989383

  14. 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

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

    PubMed

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

    2008-01-01

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

  16. Interaction of the alpha-adrenoceptor agonist oxymetazoline with serotonin 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D receptors.

    PubMed

    Schoeffter, P; Hoyer, D

    1991-04-17

    Oxymetazoline was recognized with nanomolar affinity by 5-HT1A, 5-HT1B and 5-HT1D binding sites and mimicked the effects of 5-hydroxytryptamine with about the same potency and intrinsic activity as the endogenous amine in the corresponding functional tests. At 5-HT1C receptors, oxymetazoline behaved as a mixed agonist-antagonist. Clonidine had minimal activity. Methiothepin antagonized the effects of oxymetazoline (7.4 less than pKB less than 8.8). Thus, oxymetazoline is a full and potent agonist at 5-HT1A, 5-HT1B and 5-HT1D receptors and a partial agonist at 5-HT1C receptors.

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

    PubMed

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

    2006-05-01

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

  18. 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.

  19. Distribution of 5-HT3, 5-HT4, and 5-HT7 Receptors Along the Human Colon

    PubMed Central

    Yaakob, Nor S; Chinkwo, Kenneth A; Chetty, Navinisha; Coupar, Ian M; Irving, Helen R

    2015-01-01

    Background/Aims Several disorders of the gastrointestinal tract are associated with abnormal serotonin (5-HT) signaling or metabolism where the 5-HT3 and 5-HT4 receptors are clinically relevant. The aim was to examine the distribution of 5-HT3, 5-HT4, and 5-HT7 receptors in the normal human colon and how this is associated with receptor interacting chaperone 3, G protein coupled receptor kinases, and protein LIN-7 homologs to extend previous observations limited to the sigmoid colon or the upper intestine. Methods Samples from ascending, transverse, descending, and sigmoid human colon were dissected into 3 separate layers (mucosa, longitudinal, and circular muscles) and ileum samples were dissected into mucosa and muscle layers (n = 20). Complementary DNA was synthesized by reverse transcription from extracted RNA and expression was determined by quantitative or end point polymerase chain reaction. Results The 5-HT3 receptor subunits were found in all tissues throughout the colon and ileum. The A subunit was detected in all samples and the C subunit was expressed at similar levels while the B subunit was expressed at lower levels and less frequently. The 5-HT3 receptor E subunit was mainly found in the mucosa layers. All splice variants of the 5-HT4 and 5-HT7 receptors were expressed throughout the colon although the 5-HT4 receptor d, g, and i variants were expressed less often. Conclusions The major differences in 5-HT receptor distribution within the human colon are in relation to the mucosa and muscular tissue layers where the 5-HT3 receptor E subunit is predominantly found in the mucosal layer which may be of therapeutic relevance. PMID:26130632

  20. Control of sensory neuron excitability by serotonin involves 5HT2C receptors and Ca(2+)-activated chloride channels.

    PubMed

    Salzer, Isabella; Gantumur, Enkhbileg; Yousuf, Arsalan; Boehm, Stefan

    2016-11-01

    Serotonin (5HT) is a constituent of the so-called "inflammatory soup" that sensitizes nociceptors during inflammation. Nevertheless, receptors and signaling mechanisms that mediate an excitation of dorsal root ganglion (DRG) neurons by 5HT remained controversial. Therefore, capsaicin-sensitive nociceptive neurons dissociated from rat DRGs were used to investigate effects of 5HT on membrane excitability and currents through ligand- as well as voltage-gated ion channels. In 58% of the neurons tested, 5HT increased action potential firing, an effect that was abolished by the 5HT2 receptor antagonist ritanserin, but not by the 5HT3 antagonist tropisetron. Unlike other algogenic mediators, such as PGE2 and bradykinin, 5HT did not affect currents through TTX-resistant Na(+) channels or Kv7 K(+) channels. In all neurons investigated, 5HT potentiated capsaicin-evoked currents through TRPV1 channels, an effect that was attenuated by antagonists at 5HT2A (4 F 4 PP), 5HT2B (SB 204741), as well as 5HT2C (RS 102221) receptors. 5HT triggered slowly arising inward Cl(-) currents in 53% of the neurons. This effect was antagonized by the 5HT2C receptor blocker only, and the current was prevented by an inhibitor of Ca(2+)-activated chloride channels (CaCC). The 5HT-induced increase in action potential firing was also abolished by this CaCC blocker and by the TRPV1 inhibitor capsazepine. Amongst the subtype selective 5HT2 antagonists, only RS 102221 (5HT2C-selectively) counteracted the rise in action potential firing elicited by 5HT. These results show that 5HT excites DRG neurons mainly via 5HT2C receptors which concomitantly mediate a sensitization of TRPV1 channels and an opening of CaCCs.

  1. 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

  2. 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. PMID:27106166

  3. Serotonin increases ERK1/2 phosphorylation in astrocytes by stimulation of 5-HT2B and 5-HT2C receptors.

    PubMed

    Li, Baoman; Zhang, Shiquen; Li, Min; Hertz, Leif; Peng, Liang

    2010-11-01

    We have previously shown that fluoxetine causes ERK(1/2) phosphorylation in cultured mouse astrocytes mediated exclusively by stimulation of 5-HT(2B) receptors (Li et al., 2008b). This raises the question whether this is also the case for serotonin (5-HT) itself. In the present study serotonin was found to induce ERK(1/2) phosphorylation by stimulation of 5-HT(2B) receptors with high affinity (EC(50): 20-30 pM), and by stimulation of 5-HT(2C) receptor with low affinity (EC(50): 1 microM or higher). ERK(1/2) phosphorylation induced by stimulation of either 5-HT(2B) or 5-HT(2C) receptors was mediated by epidermal growth factor (EGF) receptor transactivation (Peng et al., this issue), shown by the inhibitory effect of AG1478, an inhibitor of the EGF receptor tyrosine kinase, and GM6001, an inhibitor of Zn-dependent metalloproteinases, and thus of 5-HT(2B) receptor-mediated EGF receptor agonist release. It is discussed that the high potency of the 5-HT(2B)-mediated effect is consistent with literature data for binding affinity of serotonin to cloned human 5-HT(2B) receptors and with observations of low extracellular concentrations of serotonin in brain, which would allow a demonstrated moderate and modality-dependent increase in specific brain areas to activate 5-HT(2B) receptors. In contrast the relevance of the observed 5-HT(2C) receptors on astrocytes is questioned. PMID:20450948

  4. Blockade of 5-HT1A receptors by (+/-)-pindolol potentiates cortical 5-HT outflow, but not antidepressant-like activity of paroxetine: microdialysis and behavioral approaches in 5-HT1A receptor knockout mice.

    PubMed

    Guilloux, Jean-Philippe; David, Denis J P; Guiard, Bruno P; Chenu, Franck; Repérant, Christelle; Toth, Miklos; Bourin, Michel; Gardier, Alain M

    2006-10-01

    Selective serotonin reuptake inhibitors like paroxetine (Prx) often requires 4-6 weeks to achieve clinical benefits in depressed patients. Pindolol shortens this delay and it has been suggested that this effect is mediated by somatodendritic 5-hydroxytryptamine (5-HT) 1A autoreceptors. However clinical data on the beneficial effects of pindolol are conflicting. To study the effects of (+/-)-pindolol-paroxetine administration, we used genetical and pharmacological approaches in 5-HT1A knockout mice (5-HT1A-/-). Two assays, in vivo intracerebral microdialysis in awake mice and the forced swimming test (FST), were used to assess the antidepressant-like effects of this drug combination. Basal levels of extracellular serotonin, 5-HT ([5-HT]ext) in the frontal cortex (FCX) and the dorsal raphe nucleus (DRN) did not differ between the two strains of mice, suggesting a lack of tonic control of 5-HT1A autoreceptors on nerve terminal 5-HT release. Prx (1 and 4 mg/kg) dose-dependently increased cortical [5-HT]ext in both genotypes, but the effects were greater in mutants. The selective 5-HT1A receptor antagonist, WAY-100635 (0.5 mg/kg), or (+/-)-pindolol (5 and 10 mg/kg) potentiated the effects of Prx (4 mg/kg) on cortical [5-HT]ext in 5-HT1A+/+, but not in 5-HT1A-/- mice. Similar responses were obtained following local intra-raphe perfusion by reverse microdialysis of either WAY-100635 or (+/-)-pindolol (100 microM each). In the FST, Prx administration dose-dependently decreased the immobility time in both strains of mice, but the response was much greater in 5HT1A-/- mice. In contrast, (+/-)-pindolol blocked Prx-induced decreases in the immobility time while WAY-100635 had no effect in both genotypes. These findings using 5-HT1A-/- mice confirm that (+/-)-pindolol behaves as an antagonist of 5-HT1A autoreceptor in mice, but its blockade of paroxetine-induced antidepressant-like effects in the FST may be due to its binding to other neurotransmitter receptors.

  5. The influence of 5-HT2 and 5-HT4 receptor antagonists to modify drug induced disinhibitory effects in the mouse light/dark test

    PubMed Central

    Costall, Brenda; Naylor, Robert J

    1997-01-01

    The ability of 5-HT2 and 5-HT4 receptor antagonists to modify the disinhibitory profile of diazepam and other agents was investigated in male BKW mice in the light/dark test box. The 5-HT2A/2B/2C receptor antagonists ritanserin, MDL11939 and RP62203 and also methysergide, which failed to modify mouse behaviour when administered alone, caused dose-related enhancements (4 to 8 fold) in the potency of diazepam to disinhibit behavioural responding to the aversive situation of the test box. Ritanserin was shown to enhance the disinhibitory potency of other benzodiazepines, chlordiazepoxide (4 fold), temazepam (10 fold) and lorazepam (10 fold), the 5-HT1A receptor ligands, 8-OH-DPAT (25 fold), buspirone (100 fold) and lesopitron (500 fold), the 5-HT3 receptor antagonists, ondansetron (100 fold) R(+)-zacopride (100 fold) and S(−)-zacopride (greater than a 1000 fold), the substituted benzamides, sulpiride (10 fold) and tiapride (5 to 10 fold) and the cholecystokinin (CCK)A receptor antagonist, devazepide (100 fold). It also reduced the onset of action of disinhibition following treatment with the 5-HT synthesis inhibitor parachlorophenylalanine. Ritanserin failed to enhance the disinhibitory effects of the CCKB receptor antagonist CI-988, the angiotensin AT1 receptor antagonist losarten or the angiotensin converting enzyme inhibitor ceranapril. The 5-HT4 receptor antagonists SDZ205-557, GR113808 and SB204070 caused dose-related reductions in the disinhibitory effect of diazepam, returning values to those shown in vehicle treated controls. The antagonists failed to modify mouse behaviour when administered alone. GR113808 was also shown to cause a dose-related antagonism of the disinhibitory effects of chlordiazepoxide, lorazepam, 8-OH-DPAT, buspirone, lesopitron, ondansetron, R(+)-zacopride, sulpiride, tiapride, devazepide, CI-988, losarten, ceranapril and parachlorophenylalanine. It was concluded that in BKW mice (a) the failure of 5-HT2 and 5-HT4 receptor antagonists

  6. 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.

  7. 5-HT6 receptors and Alzheimer's disease.

    PubMed

    Ramírez, María Javier

    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.

  8. [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.

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

    PubMed

    Redrobe, J P; Bourin, M

    1997-05-01

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

  10. Differential involvement of 5-HT(1A) and 5-HT(1B/1D) receptors in human interferon-alpha-induced immobility in the mouse forced swimming test.

    PubMed

    Zhang, Hongmei; Wang, Wei; Jiang, Zhenzhou; Shang, Jing; Zhang, Luyong

    2010-01-01

    Although Interferon-alpha (IFN-alpha, CAS 9008-11-1) is a powerful drug in treating several viral infections and certain tumors, a considerable amount of neuropsychiatric side-effects such as depression and anxiety are an unavoidable consequence. Combination with the selective serotonin (5-HT) reuptake inhibitor (SSRI) fluoxetine (CAS 56296-78-7) significantly improved the situation. However, the potential 5-HT(1A) receptor- and 5-HT(1B) receptor-signals involved in the antidepressant effects are still unclear. The effects of 5-HT(1A) receptor- and 5-HT(1B) receptor signals were analyzed by using the mouse forced swimming test (FST), a predictive test of antidepressant-like action. The present results indicated that (1) fluoxetine (administrated intragastrically, 30 mg/kg; not subactive dose: 15 mg/kg) significantly reduced IFN-alpha-induced increase of the immobility time in the forced swimming test; (2) 5-HT(1A) receptor- and 5-HT(1B) receptor ligands alone or in combination had no effects on IFN-alpha-induced increase of the immobility time in the FST; (3) surprisingly, WAY 100635 (5-HT(1A) receptor antagonist, 634908-75-1) and 8-OH-DPAT(5-HT(1A) receptor agonist, CAS 78950-78-4) markedly enhanced the antidepressant effect of fluoxetine at the subactive dose (15 mg/kg, i. g.) on the IFN-alpha-treated mice in the FST. Further investigations showed that fluoxetine combined with WAY 100635 and 8-OH-DPAT failed to produce antidepressant effects in the FST. (4) Co-application of CGS 12066A (5-HT(1B) receptor agonist, CAS 109028-09-3) or GR 127935 (5-HT(1B/1D) receptor antagonist, CAS 148642-42-6) with fluoxetine had no synergistic effects on the IFN-alpha-induced increase of immobility time in FST. (5) Interestingly, co-administration of GR 127935, WAY 100635 and fluoxetine significantly reduced the IFN-alpha-induced increase in immobility time of FST, being more effective than co-administration of WAY 100635 and fluoxetine. All results suggest that (1) compared to

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

    PubMed

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

    2015-01-15

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

  12. Blockade of uptake for dopamine, but not norepinephrine or 5-HT, increases selection of high effort instrumental activity: Implications for treatment of effort-related motivational symptoms in psychopathology.

    PubMed

    Yohn, Samantha E; Errante, Emily E; Rosenbloom-Snow, Aaron; Somerville, Matthew; Rowland, Margaret; Tokarski, Kristin; Zafar, Nadia; Correa, Merce; Salamone, John D

    2016-10-01

    Deficits in behavioral activation, exertion of effort, and other psychomotor/motivational symptoms are frequently seen in people with depression and other disorders. Depressed people show a decision bias towards selection of low effort activities, and animal tests of effort-related decision making are being used as models of motivational dysfunctions seen in psychopathology. The present studies investigated the ability of drugs that block dopamine transport (DAT), norepinephrine transport (NET), and serotonin transport (SERT) to modulate work output in rats responding on a test of effort-related decision making (i.e., a progressive ratio (PROG)/chow feeding choice task). With this task, rats choose between working for a preferred food (high carbohydrate pellets) by lever pressing on a PROG schedule vs. obtaining a less preferred lab chow that is freely available in the chamber. The present studies focused on the effects of the selective DAT inhibitor GBR12909, the selective SERT inhibitor fluoxetine, and the selective NET inhibitors desipramine and atomoxetine. Acute and repeated administration of GBR12909 shifted choice behavior, increasing measures of PROG lever pressing but decreasing chow intake. In contrast, fluoxetine, desipramine and atomoxetine failed to increase lever pressing output, and actually decreased it at higher doses. In the behaviorally effective dose range, GBR12909 elevated extracellular dopamine levels in accumbens core as measured by microdialysis, but fluoxetine, desipramine and atomoxetine decreased extracellular dopamine. Thus, blockade of DAT increases selection of the high effort instrumental activity, while inhibition of SERT or NET does not. These results have implications for the use of monoamine uptake inhibitors for the treatment of effort-related psychiatric symptoms in humans. PMID:27329556

  13. Blockade of uptake for dopamine, but not norepinephrine or 5-HT, increases selection of high effort instrumental activity: Implications for treatment of effort-related motivational symptoms in psychopathology.

    PubMed

    Yohn, Samantha E; Errante, Emily E; Rosenbloom-Snow, Aaron; Somerville, Matthew; Rowland, Margaret; Tokarski, Kristin; Zafar, Nadia; Correa, Merce; Salamone, John D

    2016-10-01

    Deficits in behavioral activation, exertion of effort, and other psychomotor/motivational symptoms are frequently seen in people with depression and other disorders. Depressed people show a decision bias towards selection of low effort activities, and animal tests of effort-related decision making are being used as models of motivational dysfunctions seen in psychopathology. The present studies investigated the ability of drugs that block dopamine transport (DAT), norepinephrine transport (NET), and serotonin transport (SERT) to modulate work output in rats responding on a test of effort-related decision making (i.e., a progressive ratio (PROG)/chow feeding choice task). With this task, rats choose between working for a preferred food (high carbohydrate pellets) by lever pressing on a PROG schedule vs. obtaining a less preferred lab chow that is freely available in the chamber. The present studies focused on the effects of the selective DAT inhibitor GBR12909, the selective SERT inhibitor fluoxetine, and the selective NET inhibitors desipramine and atomoxetine. Acute and repeated administration of GBR12909 shifted choice behavior, increasing measures of PROG lever pressing but decreasing chow intake. In contrast, fluoxetine, desipramine and atomoxetine failed to increase lever pressing output, and actually decreased it at higher doses. In the behaviorally effective dose range, GBR12909 elevated extracellular dopamine levels in accumbens core as measured by microdialysis, but fluoxetine, desipramine and atomoxetine decreased extracellular dopamine. Thus, blockade of DAT increases selection of the high effort instrumental activity, while inhibition of SERT or NET does not. These results have implications for the use of monoamine uptake inhibitors for the treatment of effort-related psychiatric symptoms in humans.

  14. Antihistamine effect on synaptosomal uptake of serotonin, norepinephrine and dopamine

    NASA Technical Reports Server (NTRS)

    Brown, P. A.; Vernikos, J.

    1980-01-01

    A study on the effects of five H1 and H2 antihistamines on the synaptosomal uptake of serotonin (5HT), norepinephrine (NE), and dopamine (DA) is presented. Brain homogenates from female rats were incubated in Krebs-Ringer phosphate buffer solution in the presence of one of three radioactive neurotransmitters, and one of the five antihistamines. Low concentrations of pyrilamine competitively inhibited 5HT uptake, had little effect on NE uptake, and no effect on DA uptake. Promethazine, diphenhydramine, metiamide, and cimetidine had no effect on 5HT or DA uptake at the same concentration. Diphenhydramine had a small inhibitory effect on NE uptake. It is concluded that pyrilamine is a selective and potent competitive inhibitor of 5HT uptake at concentrations between .05 and .5 micromolars.

  15. Specific uptake of serotonin by murine lymphoid cells

    SciTech Connect

    Jackson, J.C.; Walker, R.F.; Brooks, W.H.; Roszman, T.L.

    1986-03-01

    Recently the authors confirmed and extended earlier observations that serotonin (5-hydroxytryptamine, 5HT) can influence immune function. Both 5HT and its precursor, 5-hydroxytryptophan inhibit the primary, in vivo antibody response to sheep red blood cells, in mice. Here, the authors report specific in vitro association of this amine with mouse splenocytes. Spleen cells from 6-8 week old CBA/J mice incorporated /sup 3/H-5HT(10/sup -8/ to 2.5 x 10/sup -6/M) in a saturable manner, at 37/sup 0/C. Specificity of uptake was indicated by competition with excess (10/sup -5/M) unlabelled 5HT and with 10/sup -5/M fluoxetine, a selective inhibitor of active 5HT reuptake in rat brain. The 5HT receptor antagonists, methysergide and cyproheptadine, also blocked 5HT uptake. Cell lysis and displacement studies revealed largely intracellular accumulation of /sup 3/H-5HT with little membrane association, in splenocytes. Hofstee analysis of uptake kinetics yielded an apparent Km of 0.82 +/- 0.22 x 10/sup -7/M and Vmax of 501 +/- 108 pM/3 x 10/sup 6/ cells/10 min. Spleen cells fractionated on Sephadex G10 showed virtually no specific 5HT uptake while peritoneal exudate cells from thioglycollate treated mice displayed 5HT uptake kinetics similar to those of splenocytes. The site of specific /sup 3/H-5HT incorporation within a population of spleen cells and the functional significance of this phenomenon to immunomodulation by 5HT remain to be elucidated.

  16. Autoradiographic Evaluation of [(18)F]FECUMI-101, a High Affinity 5-HT1AR Ligand in Human Brain.

    PubMed

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

    2016-05-12

    [(18)F]FECUMI-101 ([(18)F]1) is a 5HT1AR ligand demonstrating specific binding in brain regions corresponding to the distribution of 5-HT1AR in baboons. However, we detected moderate uptake of [(18)F]1 in baboon thalamus, a brain region lacking 5-HT1AR. We sought to investigate the relative binding of [(18)F]1 to 5-HT1AR, α1R, and 5-HT7R in vitro. Using autoradiography in human brain sections, specific binding of [(18)F]1 to 5-HT1AR was confirmed. However, [(18)F]1 also showed 26% binding to α1R in PFC. The hippocampal formation exhibited 51% and 92% binding of [(18)F]1 to α1R and 5-HT1AR, respectively. Thalamus and cerebellum showed very little binding. There is no measurable specific binding of [(18)F]1 to 5-HT7R and no effect of temperature on [(18)F]1 specific binding to 5-HT1AR or α1R. These results indicate that, while [(18)F]FECUMI-101 is not a completely selective 5-HT1AR ligand for receptor quantification, it may be useful for occupancy measurements of drugs acting at 5-HT1AR in vivo. PMID:27190597

  17. Spinal 5-HT7 receptors induce phrenic motor facilitation via EPAC-mTORC1 signaling.

    PubMed

    Fields, D P; Springborn, S R; Mitchell, G S

    2015-09-01

    Spinal serotonin type 7 (5-HT7) receptors elicit complex effects on motor activity. Whereas 5-HT7 receptor activation gives rise to long-lasting phrenic motor facilitation (pMF), it also constrains 5-HT2 receptor-induced pMF via "cross-talk inhibition." We hypothesized that divergent cAMP-dependent signaling pathways give rise to these distinct 5-HT7 receptor actions. Specifically, we hypothesized that protein kinase A (PKA) mediates cross-talk inhibition of 5-HT2 receptor-induced pMF whereas 5-HT7 receptor-induced pMF results from exchange protein activated by cAMP (EPAC) signaling. Anesthetized, paralyzed, and ventilated rats receiving intrathecal (C4) 5-HT7 receptor agonist (AS-19) injections expressed pMF for >90 min, an effect abolished by pretreatment with a selective EPAC inhibitor (ESI-05) but not a selective PKA inhibitor (KT-5720). Furthermore, intrathecal injections of a selective EPAC activator (8-pCPT-2'-Me-cAMP) were sufficient to elicit pMF. Finally, spinal mammalian target of rapamycin complex-1 (mTORC1) inhibition via intrathecal rapamycin abolished 5-HT7 receptor- and EPAC-induced pMF, demonstrating that spinal 5-HT7 receptors elicit pMF by an EPAC-mTORC1 signaling pathway. Thus 5-HT7 receptors elicit and constrain spinal phrenic motor plasticity via distinct signaling mechanisms that diverge at cAMP (EPAC vs. PKA). Selective manipulation of these molecules may enable refined regulation of serotonin-dependent spinal motor plasticity for therapeutic advantage. PMID:26269554

  18. Spinal 5-HT7 receptors induce phrenic motor facilitation via EPAC-mTORC1 signaling

    PubMed Central

    Fields, D. P.; Springborn, S. R.

    2015-01-01

    Spinal serotonin type 7 (5-HT7) receptors elicit complex effects on motor activity. Whereas 5-HT7 receptor activation gives rise to long-lasting phrenic motor facilitation (pMF), it also constrains 5-HT2 receptor-induced pMF via “cross-talk inhibition.” We hypothesized that divergent cAMP-dependent signaling pathways give rise to these distinct 5-HT7 receptor actions. Specifically, we hypothesized that protein kinase A (PKA) mediates cross-talk inhibition of 5-HT2 receptor-induced pMF whereas 5-HT7 receptor-induced pMF results from exchange protein activated by cAMP (EPAC) signaling. Anesthetized, paralyzed, and ventilated rats receiving intrathecal (C4) 5-HT7 receptor agonist (AS-19) injections expressed pMF for >90 min, an effect abolished by pretreatment with a selective EPAC inhibitor (ESI-05) but not a selective PKA inhibitor (KT-5720). Furthermore, intrathecal injections of a selective EPAC activator (8-pCPT-2′-Me-cAMP) were sufficient to elicit pMF. Finally, spinal mammalian target of rapamycin complex-1 (mTORC1) inhibition via intrathecal rapamycin abolished 5-HT7 receptor- and EPAC-induced pMF, demonstrating that spinal 5-HT7 receptors elicit pMF by an EPAC-mTORC1 signaling pathway. Thus 5-HT7 receptors elicit and constrain spinal phrenic motor plasticity via distinct signaling mechanisms that diverge at cAMP (EPAC vs. PKA). Selective manipulation of these molecules may enable refined regulation of serotonin-dependent spinal motor plasticity for therapeutic advantage. PMID:26269554

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

    PubMed

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

    2001-01-01

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

  20. Characterization, solubilization and partial purification of serotonin 5-HT1C receptors

    SciTech Connect

    Yagaloff, K.A.

    1986-01-01

    /sup 125/I-Lysergic acid diethylamide (/sup 125/I-LSD) binds with high affinity to a unique serotonergic site on rat choroid plexus. These sites were localized to choroid plexus epithelial cells using a novel high resolution autoradiographic technique. In membrane preparations, the serotonergic site density was 3100 fmol/mg protein, which is 10 fold higher than the density of any other serotonergic site in brain homogenates. The pharmacology of this site, termed the 5-HT1c site, does not match that of 5-Ht1a, 5-HT1b or 5HT2 serotonergic sites. 5-Ht1c sites were solubilized from pig choroid plexus using the zwitterionic detergent, CHAPS. High affinity labelling of the solubilized site was obtained using the serotonergic radioligand, N1-methyl-2-(/sup 125/I)lysergic acid diethylamide (/sup 125/I-MIL). Choroid plexus tumors obtained from transgenic mice were examined for the presence of serotonin 5-HT1c receptors. /sup 125/I-LSD binding to choroid plexus tumors displays a pharmacological profile that matches the properties of 5-HT1c receptors in normal choroid plexus. The tumor exhibits the highest site density of serotonin receptors (6600 fmol/mg protein) found in any tissue. /sup 125/I-LSD autoradiography of brain sections from transgenic mice shows high levels of specific labelling over the tumor. The affinities of various indolealkyl, phenlakyl and beta-carboline derivatives for the serotonin 5-HT1c receptor were measured in pig choroid plexus using /sup 125/I-MIL. Serotonin precursors and metabolites were all very weak inhibitors of specific /sup 125/I-MIL binding. Structure-affinity relationships were determined for a number of indolealkylamine analogues. Only serotonin is present in cerebrospinal fluid at concentrations near its 5-HT1c inhibition constant, suggesting that serotonin is the natural 5-HT1c agonist.

  1. 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

  2. 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

  3. Reduced signal transduction by 5-HT4 receptors after long-term venlafaxine treatment in rats

    PubMed Central

    Vidal, R; Valdizan, EM; Vilaró, MT; Pazos, A; Castro, E

    2010-01-01

    BACKGROUND AND PURPOSE The 5-HT4 receptor may be a target for antidepressant drugs. Here we have examined the effects of the dual antidepressant, venlafaxine, on 5-HT4 receptor-mediated signalling events. EXPERIMENTAL APPROACH The effects of 21 days treatment (p.o.) with high (40 mg·kg−1) and low (10 mg·kg−1) doses of venlafaxine, were evaluated at different levels of 5-HT4 receptor-mediated neurotransmission by using in situ hybridization, receptor autoradiography, adenylate cyclase assays and electrophysiological recordings in rat brain. The selective noradrenaline reuptake inhibitor, reboxetine (10 mg·kg−1, 21 days) was also evaluated on 5-HT4 receptor density. KEY RESULTS Treatment with a high dose (40 mg·kg−1) of venlafaxine did not alter 5-HT4 mRNA expression, but decreased the density of 5-HT4 receptors in caudate-putamen (% reduction = 26 ± 6), hippocampus (% reduction = 39 ± 7 and 39 ± 8 for CA1 and CA3 respectively) and substantia nigra (% reduction = 49 ± 5). Zacopride-stimulated adenylate cyclase activation was unaltered following low-dose treatment (10 mg·kg−1) while it was attenuated in rats treated with 40 mg·kg−1 of venlafaxine (% reduction = 51 ± 2). Furthermore, the amplitude of population spike in pyramidal cells of CA1 of hippocampus induced by zacopride was significantly attenuated in rats receiving either dose of venlafaxine. Chronic reboxetine did not modify 5-HT4 receptor density. CONCLUSIONS AND IMPLICATIONS Our data indicate a functional desensitization of 5-HT4 receptors after chronic venlafaxine, similar to that observed after treatment with the classical selective inhibitors of 5-HT reuptake. PMID:20880406

  4. 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

  5. Improved efficacy of fluoxetine in increasing hippocampal 5-hydroxytryptamine outflow in 5-HT(1B) receptor knock-out mice.

    PubMed

    Malagié, Isabelle; David, Denis J; Jolliet, Pascale; Hen, René; Bourin, Michel; Gardier, Alain M

    2002-05-17

    To test for the contribution of the 5-HT(1B) receptor subtype in mediating the effects of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), we used intracerebral in vivo microdialysis in awake, freely moving 5-HT(1B) receptor knock-out mice. We show that a single systemic administration of fluoxetine (1, 5 or 10 mg/kg, i.p.) increased extracellular serotonin levels [5-HT](ext) in the ventral hippocampus and frontal cortex of wild-type and mutant mice. However, in the ventral hippocampus, fluoxetine, at the three doses studied, induced a larger increase in [5-HT](ext) in knock-out than in wild-type mice. In the frontal cortex, the effect of fluoxetine did not differ between the two genotypes. The region-dependent response to fluoxetine described here in mutants confirms data we recently reported for another SSRI, paroxetine. These data suggest that 5-HT(1B) autoreceptors limit the effects of selective serotonin reuptake inhibitors on dialysate 5-HT levels at serotonergic nerve terminals located mainly in the ventral hippocampus. Alternative mechanisms, e.g., changes in 5-HT transporter and/or 5-HT(1A) receptor density in 5-HT(1B) receptor knock-out mice could also explain these findings.

  6. Brain 5-HT deficiency increases stress vulnerability and impairs antidepressant responses following psychosocial stress.

    PubMed

    Sachs, Benjamin D; Ni, Jason R; Caron, Marc G

    2015-02-24

    Brain serotonin (5-HT) deficiency and exposure to psychosocial stress have both been implicated in the etiology of depression and anxiety disorders, but whether 5-HT deficiency influences susceptibility to depression- and anxiety-like phenotypes induced by psychosocial stress has not been formally established. Most clinically effective antidepressants increase the extracellular levels of 5-HT, and thus it has been hypothesized that antidepressant responses result from the reversal of endogenous 5-HT deficiency, but this hypothesis remains highly controversial. Here we evaluated the impact of brain 5-HT deficiency on stress susceptibility and antidepressant-like responses using tryptophan hydroxylase 2 knockin (Tph2KI) mice, which display 60-80% reductions in brain 5-HT. Our results demonstrate that 5-HT deficiency leads to increased susceptibility to social defeat stress (SDS), a model of psychosocial stress, and prevents the fluoxetine (FLX)-induced reversal of SDS-induced social avoidance, suggesting that 5-HT deficiency may impair antidepressant responses. In light of recent clinical and preclinical studies highlighting the potential of inhibiting the lateral habenula (LHb) to achieve antidepressant and antidepressant-like responses, we also examined whether LHb inhibition could achieve antidepressant-like responses in FLX-insensitive Tph2KI mice subjected to SDS. Our data reveal that using designer receptors exclusively activated by designer drugs (DREADDs) to inhibit LHb activity leads to reduced SDS-induced social avoidance behavior in both WT and Tph2KI mice. This observation provides additional preclinical evidence that inhibiting the LHb might represent a promising alternative therapeutic approach under conditions in which selective 5-HT reuptake inhibitors are ineffective.

  7. Serotonin decreases aggression via 5-HT1A receptors in the fighting fish Betta splendens.

    PubMed

    Clotfelter, Ethan D; O'Hare, Erin P; McNitt, Meredith M; Carpenter, Russ E; Summers, Cliff H

    2007-01-01

    The role of the monoamine neurotransmitter serotonin (5-HT) in the modulation of conspecific aggression in the fighting fish (Betta splendens) was investigated using pharmacological manipulations. We used a fish's response to its mirror image as our index of aggressive behavior. We also investigated the effects of some manipulations on monoamine levels in the B. splendens brain. Acute treatment with 5-HT and with the 5-HT1A receptor agonist 8-OH-DPAT both decreased aggressive behavior; however, treatment with the 5-HT1A receptor antagonist WAY-100635 did not increase aggression. Chronic treatment with the selective serotonin reuptake inhibitor fluoxetine caused no significant changes in aggressive behavior and a significant decline in 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) concentrations. Treatment with the serotonin synthesis inhibitor p-chlorophenylalanine resulted in no change in aggression, yet serotonergic activity decreased significantly. Finally, a diet supplemented with L-tryptophan (Trp), the precursor to 5-HT, showed no consistent effects on aggressive behavior or brain monoamine concentrations. These results suggest a complex role for serotonin in the expression of aggression in teleost fishes, and that B. splendens may be a useful model organism in pharmacological and toxicological studies.

  8. Serotonin decreases aggression via 5-HT1A receptors in the fighting fish Betta splendens.

    PubMed

    Clotfelter, Ethan D; O'Hare, Erin P; McNitt, Meredith M; Carpenter, Russ E; Summers, Cliff H

    2007-01-01

    The role of the monoamine neurotransmitter serotonin (5-HT) in the modulation of conspecific aggression in the fighting fish (Betta splendens) was investigated using pharmacological manipulations. We used a fish's response to its mirror image as our index of aggressive behavior. We also investigated the effects of some manipulations on monoamine levels in the B. splendens brain. Acute treatment with 5-HT and with the 5-HT1A receptor agonist 8-OH-DPAT both decreased aggressive behavior; however, treatment with the 5-HT1A receptor antagonist WAY-100635 did not increase aggression. Chronic treatment with the selective serotonin reuptake inhibitor fluoxetine caused no significant changes in aggressive behavior and a significant decline in 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) concentrations. Treatment with the serotonin synthesis inhibitor p-chlorophenylalanine resulted in no change in aggression, yet serotonergic activity decreased significantly. Finally, a diet supplemented with L-tryptophan (Trp), the precursor to 5-HT, showed no consistent effects on aggressive behavior or brain monoamine concentrations. These results suggest a complex role for serotonin in the expression of aggression in teleost fishes, and that B. splendens may be a useful model organism in pharmacological and toxicological studies. PMID:17553555

  9. Increased 5-HT release mediates the anxiogenic response during benzodiazepine withdrawal: a review of supporting neurochemical and behavioural evidence.

    PubMed

    Andrews, N; File, S E

    1993-01-01

    This paper reviews the biochemical and behavioural evidence that the increased anxiety that occurs during benzodiazepine withdrawal is caused by increased 5-HT activity. In hippocampal slices taken from rats withdrawn for 24 h from chronic diazepam treatment (2 mg/kg/day for 21 days) there was a significant increase in K(+)-evoked release of [3H]5-HT and in 45Ca2+ uptake and both of these changes were reversed by the GABAB agonist, baclofen. Baclofen also reversed the anxiogenic response that is detected on withdrawal from chronic diazepam treatment. Other drugs that reduce 5-HT function (tianeptine which increases 5-HT uptake; buspirone, a 5-HT1A receptor agonist/partial agonist; zacopride, a 5-HT3 receptor antagonist) also reversed this anxiogenic response. Finally, we present data from a group of rats that did not develop tolerance to the anxiolytic effects of diazepam (2 mg/kg), even after 5 weeks treatment. This group failed to show an anxiogenic response on withdrawal from diazepam, nor was there an increase in hippocampal 5-HT release. We discuss the extent to which increased hippocampal 5-HT release can be causally linked to the increased anxiety during benzodiazepine withdrawal.

  10. Serotonin regulates β-casein expression via 5-HT7 receptors in human mammary epithelial MCF-12A cells.

    PubMed

    Chiba, Takeshi; Kimura, Soichiro; Takahashi, Katsuo; Morimoto, Yasunori; Maeda, Tomoji; Sanbe, Atsushi; Ueda, Hideo; Kudo, Kenzo

    2015-01-01

    We previously reported that serotonin (5-hydroxytryptamine; 5-HT) suppresses β-casein expression, a differentiation marker in mammary epithelial cells, via inhibition of the signal transducer and activator of transcription 5 (STAT5) phosphorylation in the human mammary epithelial cell line, MCF-12A. In this study, we investigated the expression pattern of the different 5-HT receptor subtypes in MCF-12A cells, and identified the receptors involved in 5-HT-mediated suppression of β-casein protein expression. β-Casein mRNA expression was inhibited by 30 µM 5-HT in a time-dependent manner. Treatment with 30 µM 5-HT for 72 h decreased β-casein protein levels and STAT5 phosphorylation (pSTAT5). The cells expressed four 5-HT receptors subtypes (5-HTR1D, 2B, 3A, and 7) at the mRNA and protein level, and their expression was elevated by prolactin (PRL) treatment. Additionally, the mRNA levels of 5-HTR1D and 5-HTR7 were significantly higher than the other 5-HT receptors in the cells. Tryptophan hydroxylase 1 mRNA was detectable in the cells in the absence of PRL, and PRL treatment significantly increased its expression. β-Casein and pSTAT5/STAT5 levels in the cells co-treated with 5-HT and a selective 5-HTR1D inhibitor, BRL15572, were equal to those observed in cells treated with 5-HT alone. However, in the cells co-treated with 5-HT and a selective 5-HTR7 inhibitor, SB269970, β-casein and pSTAT5/STAT5 levels increased in a SB269970 concentration-dependent manner. In conclusion, we showed that 5-HT regulates β-casein expression via 5-HTR7 in MCF-12A human mammary epithelial cells.

  11. 5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2013-01-01

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

  13. Chronic activation of 5-HT4 receptors or blockade of 5-HT6 receptors improve memory performances.

    PubMed

    Quiedeville, Anne; Boulouard, Michel; Hamidouche, Katia; Da Silva Costa-Aze, Virginie; Nee, Gerald; Rochais, Christophe; Dallemagne, Patrick; Fabis, Frédéric; Freret, Thomas; Bouet, Valentine

    2015-10-15

    5-HT4 and 5-HT6 serotonergic receptors are located in brain structures involved in memory processes. Neurochemical and behavioural studies have demonstrated that acute activation of 5-HT4 receptors (5-HT4R) or blockade of 5-HT6 receptors (5-HT6R) improves memory. To evaluate the potential of these two receptors as targets in the treatment of memory disorders encountered in several situations (ageing, Alzheimer's disease, schizophrenia, etc.), it is necessary to assess whether their beneficial effects occur after chronic administration, and if such treatment induces adverse effects. The goal of this study was to assess the effects of chronic 5-HT4R or 5-HT6R modulation on recognition memory, and to observe the possible manifestation of side effects (modification of weight gain, locomotor activity or exploratory behaviour, etc.). Mice were treated for 14 days with a 5-HT4R partial agonist (RS-67333) or a 5-HT6R antagonist (SB-271046) at increasing doses. Memory performances, locomotor activity, and exploration were assessed. Both chronic 5-HT4R activation and 5-HT6R blockade extended memory traces in an object recognition test, and were not associated with any adverse effects in the parameters assessed. Chronic modulation of one or both of these receptors thus seems promising as a potential strategy for the treatment memory deficits.

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

    PubMed

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

    2004-05-01

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

  15. Electrophysiological responses of serotoninergic dorsal raphe neurons to 5-HT1A and 5-HT1B agonists.

    PubMed

    Sprouse, J S; Aghajanian, G K

    1987-01-01

    A direct comparison was made of the effects of serotonin 5-HT1A and 5-HT1B selective compounds on the spontaneous firing rate of dorsal raphe serotoninergic neurons in chloral-hydrate-anesthetized rats. Following intravenous administration, the 5-HT1A selective compounds ipsapirone (TVX Q 7821) and LY 165163 potently inhibited single-unit activity in a dose-dependent manner whereas the 5-HT1B selective compounds, m-chlorophenylpiperazine (mCPP) and trifluoromethylphenylpiperazine (TFMPP), displayed only weak or irregular actions. Low microiontophoretic currents of ipsapirone and LY 165163 were also effective in suppressing spontaneous firing; dose-response relationships for the 5-HT1A compounds were indistinguishable from that of 5-HT itself. In contrast, dorsal raphe neurons were only weakly responsive to microiontophoretic application of mCPP and TFMPP; dose-response relationships for the 5-HT1B compounds were significantly displaced from that of 5-HT. In intracellular studies, ipsapirone and LY 165163, when added to the media bathing brain slices, mimicked the actions of 5-HT in hyperpolarizing dorsal raphe cell membranes and decreasing input resistance; however, the maximal effects of the 5-HT1A compounds on these membrane properties exceeded those of 5-HT. In summary, dorsal raphe 5-HT neurons appear highly responsive to 5-HT1A, but not to 5-HT1B compounds; these findings are discussed with regard to the 5-HT receptor subtypes as candidates for the somatodendritic autoreceptor of dorsal raphe neurons. PMID:3505364

  16. Interaction between 5-HT(1A) and 5-HT(1B) receptors: effects of 8-OH-DPAT-induced hypothermia in 5-HT(1B) receptor knockout mice.

    PubMed

    Gardier, A M; Gruwez, B; Trillat, A C; Jacquot, C; Hen, R; Bourin, M

    2001-06-15

    To test for adaptive compensatory changes that may have occurred in the functional activity of somatodendritic 5-HT(1A) receptors during the development of constitutive "knockout" mice lacking the 5-HT(1B) receptor subtype (5-HT(1B) -/- KO), we assayed for decrease in body temperature induced by an acute subcutaneous injection of the 5-HT(1A) receptor agonist, 8-hydroxy 2(di-n-propyl(amino)tetralin (8-OH-DPAT), either alone or in the presence of a selective 5-HT(1A) receptor antagonist, N-[4-(2-methoxyphenyl)-1-piperazinyl]-N-(2-pyridinyl) cyclo-hexanecarboxamide (WAY 100635). We compared dose-response curves, time course study, calculated ED(50) values (potency), maximal response to 8-OH-DPAT (efficacy) as well as measurements of the dose-dependent blockade of this response by WAY 100635 between wild-type controls and mutant mice. We found a higher efficacy of 8-OH-DPAT-induced hypothermia in 5-HT(1B) -/- KO compared to wild-type mice suggesting that an adaptive thermoregulatory process involving the functional activity of somatodendritic 5-HT(1A) receptors is altered in mutant mice lacking 5-HT(1B) receptors.

  17. Involvement of Organic Cation Transporter-3 and Plasma Membrane Monoamine Transporter in Serotonin Uptake in Human Brain Vascular Smooth Muscle Cells

    PubMed Central

    Li, Rachel W. S.; Yang, Cui; Kwan, Y. W.; Chan, S. W.; Lee, Simon M. Y.; Leung, George P. H.

    2013-01-01

    The serotonin (5-HT) uptake system is supposed to play a crucial part in vascular functions by “fine-tuning” the local concentration of 5-HT in the vicinity of 5-HT2 receptors in vascular smooth muscle cells. In this study, the mechanism of 5-HT uptake in human brain vascular smooth muscle cells (HBVSMCs) was investigated. [3H]5-HT uptake in HBVSMCs was Na+-independent. Kinetic analyses of [3H]5-HT uptake in HBVSMCs revealed a Km of 50.36 ± 10.2 mM and a Vmax of 1033.61 ± 98.86 pmol/mg protein/min. The specific serotonin re-uptake transporter (SERT) inhibitor citalopram, the specific norepinephrine transporter (NET) inhibitor desipramine, and the dopamine transporter (DAT) inhibitor GBR12935 inhibited 5-HT uptake in HBVSMCs with IC50 values of 97.03 ± 40.10, 10.49 ± 5.98, and 2.80 ± 1.04 μM, respectively. These IC50 values were 100-fold higher than data reported by other authors, suggesting that those inhibitors were not blocking their corresponding transporters. Reverse transcription-polymerase chain reaction results demonstrated the presence of mRNA for organic cation transporter (OCT)-3 and plasma membrane monoamine transporter (PMAT), but the absence of OCT-1, OCT-2, SERT, NET, and DAT. siRNA knockdown of OCT-3 and PMAT specifically attenuated 5-HT uptake in HBVSMCs. It is concluded that 5-HT uptake in HBVSMCs was mediated predominantly by a low-affinity and Na+-independent mechanism. The most probable candidates are OCT-3 and PMAT, but not the SERT. PMID:23407616

  18. 5-HT2C receptors in psychiatric disorders: A review.

    PubMed

    Chagraoui, A; Thibaut, F; Skiba, M; Thuillez, C; Bourin, M

    2016-04-01

    5-HT2Rs have a different genomic organization from other 5-HT2Rs. 5HT2CR undergoes post-transcriptional pre-mRNA editing generating diversity among RNA transcripts. Selective post-transcriptional editing could be involved in the pathophysiology of psychiatric disorders through impairment in G-protein interactions. Moreover, it may influence the therapeutic response to agents such as atypical antipsychotic drugs. Additionally, 5-HT2CR exhibits alternative splicing. Central serotonergic and dopaminergic systems interact to modulate normal and abnormal behaviors. Thus, 5HT2CR plays a crucial role in psychiatric disorders. 5HT2CR could be a relevant pharmacological target in the treatment of neuropsychiatric disorders. The development of drugs that specifically target 5-HT2C receptors will allow for better understanding of their involvement in the pathophysiology of psychiatric disorders including schizophrenia, anxiety, and depression. Among therapeutic means currently available, most drugs used to treat highly morbid psychiatric diseases interact at least partly with 5-HT2CRs. Pharmacologically, 5HT2CRs, have the ability to generate differentially distinct response signal transduction pathways depending on the type of 5HT2CR agonist. Although this receptor property has been clearly demonstrated, in vitro, the eventual beneficial impact of this property opens new perspectives in the development of agonists that could activate signal transduction pathways leading to better therapeutic efficiency with fewer adverse effects.

  19. Not All Antidepressants Are Created Equal: Differential Effects of Monoamine Uptake Inhibitors on Effort-Related Choice Behavior.

    PubMed

    Yohn, Samantha E; Collins, Samantha L; Contreras-Mora, Hector M; Errante, Emily L; Rowland, Margaret A; Correa, Merce; Salamone, John D

    2016-02-01

    Motivated behavior can be characterized by behavioral activation and high work output. Moreover, people with depression and other disorders show effort-related motivational symptoms, such as anergia, psychomotor retardation, and fatigue. Effort-based decision making is studied using tasks offering choices between high effort options leading to highly valued reinforcers vs low effort/low reward options, and such tasks could be useful as animal models of motivational symptoms. In the present studies the effort-related effects of the vesicular monoamine transport (VMAT-2) inhibitor tetrabenazine (TBZ) were investigated. TBZ blocks vesicular storage and also produces depressive symptoms in humans. Moreover, TBZ alters effort-based choice in rats, biasing animals toward low effort alternatives. The present studies investigated the ability of acute administration of various monoamine uptake inhibitors to reverse the effects of TBZ. Effort-related effects of TBZ were attenuated by the catecholamine uptake inhibitor and antidepressant bupropion, and this effect of bupropion was reversed by either D1 or D2 family antagonism. The effort-related effects of TBZ were also attenuated by the selective dopamine uptake blocker GBR12909. The 5-HT uptake inhibitor fluoxetine and the norepinephrine uptake inhibitor desipramine failed to reverse the effects of TBZ, and higher doses of these drugs, given alone or in combination with TBZ, led to further behavioral impairments. These results indicate that drugs acting on dopamine transmission are relatively effective at reversing the effort-related effects of TBZ, and are consistent with the hypothesis that drugs that enhance dopamine transmission may be effective at treating effort-related psychiatric symptoms in humans.

  20. The 5-HT1A receptor agonist flesinoxan shares discriminative stimulus properties with some 5-HT2 receptor antagonists.

    PubMed

    Herremans, A H; van der Heyden, J A; van Drimmelen, M; Olivier, B

    1999-10-01

    Ten homing pigeons were trained to discriminate the selective 5-HT1A receptor agonist flesinoxan (0.25 mg/kg p.o.) from its vehicle in a fixed-ratio (FR) 30 two-key operant drug discrimination procedure. The 5-HT2 receptor antagonist mianserin (ED50 = 4.8 mg/kg) fully substituted for flesinoxan, whereas ketanserin, ritanserin, mesulergine, and SB200646A substituted only partially, suggesting an interaction between 5-HT1A and 5-HT2 receptors. However, the 5-HT2 receptor agonists [DOI (0.6 mg/kg), TFMPP (10 mg/kg), mCPP (4 mg/kg)] were unable to antagonize the flesinoxan cue. The 5-HT1A receptor antagonists DU125530 (0.5-13 mg/kg) and WAY100,635 (0.1-1 mg/kg) partially antagonized the generalization of mianserin to flesinoxan. Taken together, these results are in accordance with the hypothesis that 5-HT1A receptor activation exerts an inhibitory effect on activation of 5-HT2 receptors. These results are in broad agreement with existing theories on 5-HT1A and 5-HT2 receptor interaction. Furthermore, it is argued that the discriminative stimulus properties of a drug may undergo qualitative changes with prolonged training.

  1. Prostaglandin potentiates 5-HT responses in stomach and ileum innervating visceral afferent sensory neurons

    SciTech Connect

    Kim, Sojin; Jin, Zhenhua; Lee, Goeun; Park, Yong Seek; Park, Cheung-Seog; Jin, Young-Ho

    2015-01-02

    Highlights: • Prostaglandin E2 (PGE{sub 2}) effect was tested on visceral afferent neurons. • PGE{sub 2} did not evoke response but potentiated serotonin (5-HT) currents up to 167%. • PGE{sub 2}-induced potentiation was blocked by E-prostanoid type 4 receptors antagonist. • PGE{sub 2} effect on 5-HT response was also blocked by protein kinase A inhibitor KT5720. • Thus, PGE{sub 2} modulate visceral afferent neurons via synergistic signaling with 5-HT. - Abstract: Gastrointestinal disorder is a common symptom induced by diverse pathophysiological conditions that include food tolerance, chemotherapy, and irradiation for therapy. Prostaglandin E{sub 2} (PGE{sub 2}) level increase was often reported during gastrointestinal disorder and prostaglandin synthetase inhibitors has been used for ameliorate the symptoms. Exogenous administration of PGE{sub 2} induces gastrointestinal disorder, however, the mechanism of action is not known. Therefore, we tested PGE{sub 2} effect on visceral afferent sensory neurons of the rat. Interestingly, PGE{sub 2} itself did not evoked any response but enhanced serotonin (5-HT)-evoked currents up to 167% of the control level. The augmented 5-HT responses were completely inhibited by a 5-HT type 3 receptor antagonist, ondansetron. The PGE{sub 2}-induced potentiation were blocked by a selective E-prostanoid type4 (EP{sub 4}) receptors antagonist, L-161,982, but type1 and 2 receptor antagonist AH6809 has no effect. A membrane permeable protein kinase A (PKA) inhibitor, KT5720 also inhibited PGE{sub 2} effects. PGE{sub 2} induced 5-HT current augmentation was observed on 15% and 21% of the stomach and ileum projecting neurons, respectively. Current results suggest a synergistic signaling in visceral afferent neurons underlying gastrointestinal disorder involving PGE{sub 2} potentiation of 5-HT currents. Our findings may open a possibility for screen a new type drugs with lower side effects than currently using steroidal prostaglandin

  2. 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.

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

    PubMed

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

    2015-02-01

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

  4. Recombinant saphenous vein 5-HT1B receptors of the rabbit: comparative pharmacology with human 5-HT1B receptors.

    PubMed

    Wurch, T; Palmier, C; Colpaert, F C; Pauwels, P J

    1997-01-01

    1. The rabbit recombinant saphenous vein 5-hydroxytryptamine1B (r 5-HT1B) receptor stably transfected in rat C6-glial cells was characterized by measuring adenosine 3':5'-cyclic monophosphate (cycle AMP) formation upon exposure to various 5-HT receptor ligands. The effects of agonists and antagonists were compared with their effects determined previously at the human cloned 5-HT1B (h 5-HT1B) receptor under similar experimental conditions. 2. Intact C6-glial cells expressing rb HT1B receptors exhibited [3H]-5-carboxamidotryptamine (5-CT) binding sites with a Kd of 0.80 +/- 0.13 nM and a Bmax between 225 to 570 fmol mg-1 protein. The binding affinities of a series of 5-HT receptor ligands determined in a membrane preparation with [3H]-5-CT or [3H]-N-[4-methoxy-3-(4-methylpiperazin-1-yl)phenyl]-3-methyl-4-(-4 -pyridyl) benzamide (GR 125,743) were similar. With the exception of ketanserin, ligand affinities were comparable to those determined at the clones h 5-HT1B receptor site. 3. rb 5-HT1B receptors were negatively coupled to cyclic AMP formation upon stimulation with 5-HT agonists. Of the several 5-HT agonists tested, 5-CT was the most potent, the potency rank order being: 5-CT > 5-HT > zolmitriptan > naratriptan > rizatriptan > sumatriptan > R (+)-8-(hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). The maximal responses of these agonists were similar to those induced by 5-HT. The potency of these agonists showed a positive correlation (r2 = 0.87; P < 0.002) with their potency at the cloned h 5-HT1B receptor subtype. 4. 2'-Methyl-4-(5-methyl-[1,2,4]oxadiazol-3-yl)-biphenyl-4-carboxylic acid [4-methoxy-e-(4-methyl-piperazin-1-yl)-phenyl]-amide (GR 127,935), methiothepin and ketanserin each behaved as silent, competitive antagonists at rb 5HT1B receptors; pKB values were 8.41, 8.32 and 7.05, respectively when naratriptan was used as an agonist. These estimates accorded with their binding affinities and the potencies found on 5-HT and/or sumatriptan

  5. In Vivo Electrochemical Evidence for Simultaneous 5-HT and Histamine Release in the Rat Substantia Nigra pars Reticulata Following Medial Forebrain Bundle Stimulation

    PubMed Central

    Hashemi, Parastoo; Dankoski, Elyse C.; Wood, Kevin M.; Ambrose, R. Ellen; Wightman, R. Mark

    2011-01-01

    Exploring the mechanisms of serotonin (5-hydoxytryptophan (5-HT)) in the brain requires an in vivo method that combines fast temporal resolution with chemical selectivity. Fast-scan cyclic voltammetry (FSCV) is a technique with sufficient temporal and chemical resolution for probing dynamic 5-HT neurotransmission events; however, traditionally it has not been possible to probe in vivo 5-HT mechanisms. Recently, we optimized FSCV for measuring 5-HT release and uptake in vivo in the substantia nigra pars reticulata (SNR) with electrical stimulation of the dorsal raphe nucleus (DRN) in the rat brain. Here, we address technical challenges associated with rat DRN surgery by electrically stimulating 5-HT projections in the medial forebrain bundle (MFB), a more accessible anatomical location. MFB stimulation elicits 5-HT in the SNR; furthermore, we find simultaneous release of an additional species. We use electrochemical and pharmacological methods and describe physiological, anatomical and independent chemical analyses to identify this species as histamine. We also show pharmacologically that increasing the lifetime of extracellular histamine significantly decreases 5-HT release, most likely due to increased activation of histamine H-3 receptors that inhibit 5-HT release. Despite this, under physiological conditions, we find by kinetic comparisons of DRN and MFB stimulations that the simultaneous release of histamine does not interfere with the quantitative 5-HT concentration profile. We therefore present a novel and robust electrical stimulation of the MFB that is technically less challenging than DRN stimulation to study 5-HT and histamine release in the SNR. PMID:21682723

  6. Involvement of the 5-HT(1A) receptor in the anti-immobility effects of fluvoxamine in the forced swimming test and mouse strain differences in 5-HT(1A) receptor binding.

    PubMed

    Sugimoto, Yumi; Furutani, Sachiko; Kajiwara, Yoshinobu; Hirano, Kazufumi; Yamada, Shizuo; Tagawa, Noriko; Kobayashi, Yoshiharu; Hotta, Yoshihiro; Yamada, Jun

    2010-03-10

    We previously demonstrated the presence of strain differences in baseline immobility time and sensitivity to the selective serotonin reuptake inhibitor (SSRI) fluvoxamine in five strains of mice (ICR, ddY, C57BL, DBA/2 and BALB/c mice). Furthermore, variations in serotonin (5-HT) transporter binding in the brain were strongly related to strain differences in baseline immobility and sensitivity to fluvoxamine. In the present study, we examined the involvement of the 5-HT(1A) receptor in anti-immobility effects in DBA/2 mice, which show high sensitivity to fluvoxamine. The anti-immobility effects of fluvoxamine in DBA/2 mice were inhibited by the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY 100635). However, the 5-HT(1B) receptor antagonist 3-[3-(dimethylamino)propyl]-4-hydroxy-N-[4-(4-pyridinyl)phenyl]benzamide (GR55562), the 5-HT(2) receptor antagonist 6-methyl-1-(methylethyl)-ergoline-8beta-carboxylic acid 2-hydroxy-1-methylpropyl ester (LY 53857), the 5-HT(3) receptor antagonist ondansetron and the 5-HT(4) receptor antagonist 4-amino-5-chloro-2-methoxy-benzoic acid 2-(diethylamino)ethyl ester (SDZ 205,557) did not influence the anti-immobility effects of fluvoxamine in DBA/2 mice. These results suggest that fluvoxamine-induced antidepressant-like effects in DBA/2 mice are mediated by the 5-HT(1A) receptor. We analyzed 5-HT(1A) receptor binding in the brains of five strains of mice. Strain differences in 5-HT(1A) receptor binding were observed. 5-HT(1A) receptor binding in brain was not correlated with baseline immobility time in the five strains of mice examined. These results suggest that, although the anti-immobility effects of fluvoxamine in DBA/2 mice are mediated by the 5-HT(1A) receptor, strain differences in 5-HT(1A) receptor binding are not related to variation in immobility time and responses to fluvoxamine.

  7. Serotonin via 5-HT7 receptors activates p38 mitogen-activated protein kinase and protein kinase C epsilon resulting in interleukin-6 synthesis in human U373 MG astrocytoma cells.

    PubMed

    Lieb, Klaus; Biersack, Lisa; Waschbisch, Anne; Orlikowski, Sonja; Akundi, Ravi Shankar; Candelario-Jalil, Eduardo; Hüll, Michael; Fiebich, Bernd L

    2005-05-01

    Serotonin [5-hydroxytryptamine (5-HT)] is a widely distributed neurotransmitter which is involved in neuroimmunomodulatory processes. Previously, it has been demonstrated that 5-HT may induce interleukin (IL)-6 expression in primary rat hippocampal astrocytes. The present study was undertaken to investigate the molecular pathways underlying this induction of IL-6 synthesis. As a model system, we used the human astrocytoma cell line U373 MG, which synthesizes IL-6 upon stimulation with various inducers. 5-HT dose- and time-dependently induced IL-6 protein synthesis. We identified several 5-HT receptors to be expressed on U373 MG cells, including the 5-HT1D, 5-HT2A, 5-HT3 and 5-HT7 receptors. In this report, we show that the 5-HT-induced IL-6 release is mediated by the 5-HT7 receptor based on several agonist/antagonists that were used. 5-HT-induced IL-6 synthesis is inhibited by the partially selective 5-HT7 receptor antagonist, pimozide, and the selective antagonist SB269970. Furthermore, IL-6 synthesis was induced by the 5-HT7 receptor agonist carboxamidotryptamin. In addition, we found p38 MAPKs and protein kinase C (PKC) epsilon to be involved in 5-HT-induced IL-6 synthesis as specific inhibitors of these enzymes (SB202190 and RO-31-8425, respectively) blocked 5-HT-induced IL-6 synthesis. Furthermore, 5-HT mediated the phosphorylation of both p38 MAPK as well as the PKC epsilon isoform. The p42/44 MAPKs, however, were not involved in 5-HT-induced IL-6 synthesis. This study shows, for the first time, a central role of 5-HT7 receptor linked to p38 MAPK and PKC epsilon for the induction of cytokine synthesis in astrocytic cells. PMID:15836614

  8. Pharmacological Characterization of 5-HT1A Autoreceptor-Coupled GIRK Channels in Rat Dorsal Raphe 5-HT Neurons

    PubMed Central

    Montalbano, Alberto; Corradetti, Renato; Mlinar, Boris

    2015-01-01

    G protein-activated inwardly rectifying potassium (GIRK) channels in 5-HT neurons are assumed to be principal effectors of 5-hydroxytryptamine 1A (5-HT1A) autoreceptors, but their pharmacology, subunit composition and the role in regulation of 5-HT neuron activity have not been fully elucidated. We sought for a pharmacological tool for assessing the functional role of GIRK channels in 5-HT neurons by characterizing the effects of drugs known to block GIRK channels in the submicromolar range of concentrations. Whole-cell voltage-clamp recording in brainstem slices were used to determine concentration-response relationships for the selected GIRK channel blockers on 5-HT1A autoreceptor-activated inwardly rectifying K+ conductance in rat dorsal raphe 5-HT neurons. 5-HT1A autoreceptor-activated GIRK conductance was completely blocked by the nonselective inwardly rectifying potassium channels blocker Ba2+ (EC50 = 9.4 μM, full block with 100 μM) and by SCH23390 (EC50 = 1.95 μM, full block with 30 μM). GIRK-specific blocker tertiapin-Q blocked 5-HT1A autoreceptor-activated GIRK conductance with high potency (EC50 = 33.6 nM), but incompletely, i.e. ~16% of total conductance resulted to be tertiapin-Q-resistant. U73343 and SCH28080, reported to block GIRK channels with submicromolar EC50s, were essentially ineffective in 5-HT neurons. Our data show that inwardly rectifying K+ channels coupled to 5-HT1A autoreceptors display pharmacological properties generally expected for neuronal GIRK channels, but different from GIRK1-GIRK2 heteromers, the predominant form of brain GIRK channels. Distinct pharmacological properties of GIRK channels in 5-HT neurons should be explored for the development of new therapeutic agents for mood disorders. PMID:26460748

  9. An in vitro investigation of the cardiovascular effects of the 5-HT(4) receptor selective agonists, velusetrag and TD-8954.

    PubMed

    Beattie, D T; Higgins, D L; Ero, M P; Amagasu, S M; Vickery, R G; Kersey, K; Hopkins, A; Smith, J A M

    2013-01-01

    The 5-HT(4) receptor agonists, and gastrointestinal (GI) prokinetic agents, cisapride and tegaserod, lack selectivity for the 5-HT(4) receptor. Cisapride is a potent human ether-à-go-go-related gene (hERG) potassium channel inhibitor while cisapride and tegaserod have significant affinity for 5-HT(1) and 5-HT(2) receptor subtypes. Marketing of both compounds was discontinued due to cardiovascular concerns (cardiac arrhythmias with cisapride and ischemic events with tegaserod). The reported association of tegaserod with ischemia has been postulated to involve coronary artery constriction or augmentation of platelet aggregation. This in vitro study investigated the effects of two of the new generation of highly selective 5-HT(4) receptor agonists, velusetrag and TD-8954, on canine, porcine and human coronary artery tone, human platelet aggregation and hERG potassium channel conductance. No significant off-target actions of velusetrag or TD-8954 were identified in these, and prior, studies. While cisapride inhibited potently the hERG channel currents, tegaserod failed to affect platelet aggregation, and had only a small contractile effect on the canine coronary artery at high concentrations. Tegaserod inhibited the 5-HT-induced contractile response in the porcine coronary artery. New generation 5-HT(4) receptor agonists hold promise for the treatment of patients suffering from GI motility disorders with a reduced cardiovascular risk. PMID:23201772

  10. Effects of 2-substituted-4-phenylquinolines on uptake of serotonin and norepinephrine by isolated brain synaptosomes

    SciTech Connect

    Alhaider, A.A.; Lein, E.J.; Ransom, R.W.; Bolger, M.B.

    1987-03-02

    In this present communication, the in vitro inhibition of the uptake of (/sup 3/H)-L-norepinephrine ((/sup 3/H) NE) and (/sup 3/H)-Serotonin ((/sup 3/H) 5-HT) by eleven synthesized 2-substituted-4-phenylquionlines were studied using rate brain synaptosomal preparations. Compounds with an open side chain were relatively weak inhibitors of the synaptosomal uptake of (/sup 3/H) NE and (/sup 3/H) 5HT. Compounds having a distance of three atoms between the terminal basic nitrogen of the side chain and the quinoline ring were better inhibitors of serotonin uptake than those compounds having a four-atom distance. The replacement of the side chain with a piperazine ring produced compounds which were more potent and selective inhibitors of the uptake of either (/sup 3/H) 5-HT or (/sup 3/H) NE. Further structure-activity relationships are also discussed. 13 references, 1 table.

  11. Antidepressant and anxiolytic effects of selective 5-HT6 receptor agonists in rats

    PubMed Central

    Carr, Gregory V.; Schechter, Lee E.; Lucki, Irwin

    2010-01-01

    Rationale Although selective serotonin reuptake inhibitors (SSRIs) produce clinical therapeutic effects on depression and anxiety through augmentation of serotonergic neurotransmission, there is little known about the potential contributions of the 5-HT6 receptor in the treatment of mood disorders. Objectives The aim of this study was to test the potential antidepressant-like and anxiolytic-like effects of the 5-HT6 receptor agonists WAY-208466 and WAY-181187 using established behavioral tests in rats. Methods In order to determine if the 5-HT6 receptor agonists possess antidepressant-like activity, rats were treated with WAY-208466 or WAY-181187 and tested in the modified rat forced swim test (FST). Also, the potential anxiolytic-like effects of WAY-208466 and WAY-181187 were measured using the defensive burying (DB) test and novelty-induced hypophagia (NIH) test. Results WAY-208466 and WAY-181187 produced both antidepressant-like and anxiolytic-like effects. Both compounds decreased immobility and increased swimming behavior in the FST. The effects of the 5-HT6 receptor agonists were similar to those seen after treatment with the SSRI fluoxetine. Both 5-HT6 receptor agonists also decreased burying duration in the DB test, indicative of anxiolytic activity in the test. The anxiolytic effects of WAY-208466 were reproduced in the NIH test. Assessment of the anxiolytic effects of WAY-181187 in the NIH was confounded by alterations in home cage feeding behavior. Conclusions These findings suggest that 5-HT6 receptor agonists may represent a new class of potential antidepressant and anxiolytic compounds and could possess a number of advantages over currently available treatments, including rapid onset of anxiolytic efficacy. PMID:20217056

  12. 5-HT1A Agonist Properties Contribute to a Robust Response to Vilazodone in the Novelty Suppressed Feeding Paradigm

    PubMed Central

    Garcia-Garcia, Alvaro L.; Navarro-Sobrino, Míriam; Pilosof, Gila; Banerjee, Pradeep; Dranovsky, Alex

    2016-01-01

    Background: Differences in 5-HT1A receptor function have been implicated in vulnerability to depression and in response to treatment. Adding 5-HT1A partial agonists to selective serotonin reuptake inhibitors has been touted as a strategy to increase their efficacy. Here we use the novelty suppressed feeding paradigm to compare the effects of vilazodone, a high-potency selective serotonin reuptake inhibitor, with high affinity for 5-HT1A receptors to the reference selective serotonin reuptake inhibitor fluoxetine across several mouse strains that differ in their response to selective serotonin reuptake inhibitors. Methods: To confirm 5-HT1A agonist activity, body temperature was measured after acute administration of vilazodone or fluoxetine, as administration of 5-HT1A agonists induces hypothermia. We next used 3 strains of mice to examine the effects of the drugs on latency in the novelty suppressed feeding, a paradigm generally sensitive to chronic but not acute effects of antidepressants. Results: Vilazodone induces robust hypothermia and blocks stress-induced hyperthermia in a 5-HT1A-dependent manner, consistent with agonist effects at 5-HT1A autoreceptors. In 129SvEv mice, vilazodone (10mg/kg/d) reduces the latency to eat in the novelty suppressed feeding test within 8 days, while no effect of fluoxetine (20mg/kg/d) was detected at that time. In contrast, both vilazodone and fluoxetine are effective at decreasing latency to eat in the novelty suppressed feeding paradigm in a strain with low autoreceptor levels. In mice with higher autoreceptor levels, no significant difference was detected between fluoxetine and vehicle (P=.8) or vilazodone and vehicle (P=.06). Conclusion: In mice, vilazodone may offer advantages in time of onset and efficacy over a reference selective serotonin reuptake inhibitor in the novelty suppressed feeding test. PMID:27352617

  13. The action of SDZ 205,557 at 5-hydroxytryptamine (5-HT3 and 5-HT4) receptors.

    PubMed Central

    Eglen, R. M.; Alvarez, R.; Johnson, L. G.; Leung, E.; Wong, E. H.

    1993-01-01

    1. The interaction of the novel antagonist, SDZ 205,557 (2-methoxy-4-amino-5-chloro benzoic acid 2-(diethylamino) ethyl ester), at 5-HT3 and 5-HT4 receptors has been assessed in vitro and in vivo. 2. In guinea-pig hippocampus and in the presence of 0.4 microM 5-carboxamidotryptamine, 5-HT4-mediated stimulation of adenylyl cyclase was competitively antagonized by SDZ 205,557, with a pA2 value of 7.5, and a Schild slope of 0.81. In rat carbachol-contracted oesophagus, 5-HT4-receptor mediated relaxations were surmountably antagonized by SDZ 205,557 with a similar pA2 value (7.3). This value was agonist-independent with the exception of (R)-zacopride, against which a significantly lower value (6.4) was observed. 3. In functional studies of 5-HT3 receptors, SDZ 205,557 exhibited an affinity of 6.2 in guinea-pig ileum compared with 6.9 at binding sites labelled by [3H]-quipazine in NG108-15 cells. In the anaesthetized, vagotomized micropig, SDZ 205,557 produced only a transient blockade of 5-HT4-mediated tachycardia. This contrasted with tropisetron, which was active for over 60 min after administration. The half-lives for the inhibitory responses of SDZ 205,557 and tropisetron were 23 and 116 min, respectively. 4. In conclusion, SDZ 205,557 has similar affinity for 5-HT3 and 5-HT4 receptors. The apparent selectivity observed in guinea-pig is due to the atypical nature of the 5-HT3 receptor in this species. The short duration of action of this novel antagonist may complicate its use in vivo. SDZ 205,557 should, therefore, be used with appropriate caution in studies defining the 5-HT4 receptor. PMID:8448587

  14. 5-HT4 receptors in isolated human corpus cavernosum?

    PubMed

    Hayes, E S; Adaikan, P G; Ratnam, S S; Ng, S C

    1999-08-01

    The novel serotonin subtype-4 (5-HT4) receptor agonist, SC53116 (SC), produced a limited relaxation of noradrenaline (NA) pre-contracted human corpus cavernosum (CC) smooth muscle in vitro. This effect was not significantly attenuated by the 5-HT4 antagonist SDZ250557 (SDZ). In the presence of (+/-) pindolol (1 microM) and methysergide (1 microM), employed to mask 5-HT1 and beta-adrenergic, and 5-HT2 receptors respectively, SC failed to relax NA pre-contracted CC strips to a greater extent than saline. Functional cAMP dependent relaxation pathways were demonstrated by a significant reduction in NA induced tone by prostaglandin E1 (PGE1) and isopropylnoradrenaline (IPNA), the action of the latter compound was effectively eliminated in the presence of (+/-) pindolol. Relaxation of NA induced tone caused by the nitric oxide donor nitro-glycerine (NTG) was significant and similar in the absence and presence of the 5-HT and beta-adrenergic antagonists. The results of this present study indicate that human corporal smooth muscle does not contain 5-HT4 receptors and that, although compounds like SC act to relax non-vascular smooth muscle via cAMP dependent mechanisms, 5-HT4 receptor agonists may be expected to be of limited utility in triggering cAMP dependent relaxation responses in human CC.

  15. Matrix stiffness affects endocytic uptake of MK2-inhibitor peptides.

    PubMed

    Brugnano, Jamie L; Panitch, Alyssa

    2014-01-01

    In this study, the role of substrate stiffness on the endocytic uptake of a cell-penetrating peptide was investigated. The cell-penetrating peptide, an inhibitor of mitogen-activated protein kinase activated protein kinase II (MK2), enters a primary mesothelial cell line predominantly through caveolae. Using tissue culture polystyrene and polyacrylamide gels of varying stiffness for cell culture, and flow cytometry quantification and enzyme-linked immunoassays (ELISA) for uptake assays, we showed that the amount of uptake of the peptide is increased on soft substrates. Further, peptide uptake per cell increased at lower cell density. The improved uptake seen on soft substrates in vitro better correlates with in vivo functional studies where 10-100 µM concentrations of the MK2 inhibitor cell penetrating peptide demonstrated functional activity in several disease models. Additional characterization showed actin polymerization did not affect uptake, while microtubule polymerization had a profound effect on uptake. This work demonstrates that cell culture substrate stiffness can play a role in endocytic uptake, and may be an important consideration to improve correlations between in vitro and in vivo drug efficacy.

  16. Matrix Stiffness Affects Endocytic Uptake of MK2-Inhibitor Peptides

    PubMed Central

    Brugnano, Jamie L.; Panitch, Alyssa

    2014-01-01

    In this study, the role of substrate stiffness on the endocytic uptake of a cell-penetrating peptide was investigated. The cell-penetrating peptide, an inhibitor of mitogen-activated protein kinase activated protein kinase II (MK2), enters a primary mesothelial cell line predominantly through caveolae. Using tissue culture polystyrene and polyacrylamide gels of varying stiffness for cell culture, and flow cytometry quantification and enzyme-linked immunoassays (ELISA) for uptake assays, we showed that the amount of uptake of the peptide is increased on soft substrates. Further, peptide uptake per cell increased at lower cell density. The improved uptake seen on soft substrates in vitro better correlates with in vivo functional studies where 10–100 µM concentrations of the MK2 inhibitor cell penetrating peptide demonstrated functional activity in several disease models. Additional characterization showed actin polymerization did not affect uptake, while microtubule polymerization had a profound effect on uptake. This work demonstrates that cell culture substrate stiffness can play a role in endocytic uptake, and may be an important consideration to improve correlations between in vitro and in vivo drug efficacy. PMID:24400117

  17. Effect of Uptake-one inhibitors on the uptake of norepinephrine and metaiodobenzylguanidine

    SciTech Connect

    Tobes, M.C.; Jaques, S. Jr.; Wieland, D.M.; Sisson, J.C.

    1985-08-01

    The mechanisms underlying the uptake of the radiopharmaceutical metaiodobenzylguanidine (MIBG) and the catecholamine norepinephrine (NE) were studied using cultured bovine adrenomedullary cells as an in vitro model system. Sodium-dependent and sodium-independent uptake systems have been identified and characterized for both MIBG and NE. The sodium-dependent uptake of Ne and MIBG was inhibited by the selective Uptake-one inhibitors, desmethylimipramine (DMI) and cocaine, whereas the sodium-independent uptake for NE and MIBG was much less sensitive to inhibition by these agents. The sodium-dependent uptake system fulfills the criteria for the neuronal Uptake-one system, and the sodium-independent uptake system fulfills the criteria for a passive diffusion mechanism. Arterial concentrations proximal to the dog adrenal were very small suggesting that the sodium-dependent (Uptake-one) system is predominant in vivo. Consistent with the in vitro observations, the in vivo uptake of MIBG and NE into dog adrenal medullae was effectively blocked by pretreatment with DMI or cocaine. Therefore, iodine-131 MIBG scintigraphy of the adrenal appears to reflect uptake by way of the Uptake-one system.

  18. 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

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2015-07-15

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

  1. 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.

  2. Signal Transduction Mechanism for Serotonin 5-HT2B Receptor-Mediated DNA Synthesis and Proliferation in Primary Cultures of Adult Rat Hepatocytes.

    PubMed

    Naito, Kota; Tanaka, Chizuru; Mitsuhashi, Manami; Moteki, Hajime; Kimura, Mitsutoshi; Natsume, Hideshi; Ogihara, Masahiko

    2016-01-01

    The involvement of serotonin (5-hydroxytryptamine; 5-HT) and the 5-HT2 receptor subtypes in the induction of DNA synthesis and proliferation was investigated in primary cultures of adult rat hepatocytes to elucidate the intracellular signal transduction mechanisms. Hepatocyte parenchymal cells maintained in a serum-free, defined medium, synthesized DNA and proliferated in the presence of 5-HT or a selective 5-HT2B receptor agonist, BW723C86, but not in the presence of 5-HT2A, or 5-HT2C receptor agonists (TCB-2 and CP809101, respectively), in a time- and dose-dependent manner. A selective 5-HT2B receptor antagonist, LY272015 (10(-7) M), and a specific phospholipase C (PLC) inhibitor, U-73122 (10(-6) M), as well as specific inhibitors of growth-related signal transducers-including AG1478, LY294002, PD98059, and rapamycin-completely inhibited 5-HT (10(-6) M)- or BW723C86 (10(-6) M)-induced hepatocyte DNA synthesis and proliferation. Both 5-HT and BW723C86 were shown to significantly stimulate the phosphorylation of epidermal growth factor (EGF)/transforming growth factor (TGF)-α receptor tyrosine kinase (p175 kDa) and extracellular signal-regulated kinase (ERK) 2 on Western blot analysis. These results suggest that the proliferative mechanism of activating 5-HT is mediated mainly through 5-HT2B receptor-stimulated Gq/PLC and EGF/TGF-α-receptor/phosphatidylinositol 3-kinase (PI3K)/ERK2/mammalian target of rapamycin (mTOR) signaling pathways in primary cultured hepatocytes.

  3. 5-HT(6) receptor recruitment of mTOR as a mechanism for perturbed cognition in schizophrenia.

    PubMed

    Meffre, Julie; Chaumont-Dubel, Séverine; Mannoury la Cour, Clotilde; Loiseau, Florence; Watson, David J G; Dekeyne, Anne; Séveno, Martial; Rivet, Jean-Michel; Gaven, Florence; Déléris, Paul; Hervé, Denis; Fone, Kevin C F; Bockaert, Joël; Millan, Mark J; Marin, Philippe

    2012-10-01

    Cognitive deficits in schizophrenia severely compromise quality of life and are poorly controlled by current antipsychotics. While 5-HT(6) receptor blockade holds special promise, molecular substrates underlying their control of cognition remain unclear. Using a proteomic strategy, we show that 5-HT(6) receptors physically interact with several proteins of the mammalian target of rapamycin (mTOR) pathway, including mTOR. Further, 5-HT(6) receptor activation increased mTOR signalling in rodent prefrontal cortex (PFC). Linking this signalling event to cognitive impairment, the mTOR inhibitor rapamycin prevented deficits in social cognition and novel object discrimination induced by 5-HT(6) agonists. In two developmental models of schizophrenia, specifically neonatal phencyclidine treatment and post-weaning isolation rearing, the activity of mTOR was enhanced in the PFC, and rapamycin, like 5-HT(6) antagonists, reversed these cognitive deficits. These observations suggest that recruitment of mTOR by prefrontal 5-HT(6) receptors contributes to the perturbed cognition in schizophrenia, offering new vistas for its therapeutic control.

  4. 5-HT2B antagonism arrests non-canonical TGF-β1-induced valvular myofibroblast differentiation

    PubMed Central

    Hutcheson, Joshua D.; Ryzhova, Larisa M.; Setola, Vincent; Merryman, W. David

    2012-01-01

    Transforming growth factor-β1 (TGF-β1) induces myofibroblast activation of quiescent aortic valve interstitial cells (AVICs), a differentiation process implicated in calcific aortic valve disease (CAVD). The ubiquity of TGF-β1 signaling makes it difficult to target in a tissue specific manner; however, the serotonin 2B receptor (5-HT2B) is highly localized to cardiopulmonary tissues and agonism of this receptor displays pro-fibrotic effects in a TGF-β1-dependent manner. Therefore, we hypothesized that antagonism of 5-HT2B opposes TGF-β1-induced pathologic differentiation of AVICs and may offer a druggable target to prevent CAVD. To test this hypothesis, we assessed the interaction of 5-HT2B antagonism with canonical and non-canonical TGF-β1 pathways to inhibit TGF-β1-induced activation of isolated porcine AVICs in vitro. Here we show that AVIC activation and subsequent calcific nodule formation is completely mitigated by 5-HT2B antagonism. Interestingly, 5-HT2B antagonism does not inhibit canonical TGF-β1 signaling as identified by Smad3 phosphorylation and activation of a partial plasminogen activator inhibitor-1 promoter (PAI-1, a transcriptional target of Smad3), but prevents non-canonical p38 MAPK phosphorylation. It was initially suspected that 5-HT2B antagonism prevents Src tyrosine kinase phosphorylation; however, we found that this is not the case and time-lapse microscopy indicates that 5-HT2B antagonism prevents non-canonical TGF-β1 signaling by physically arresting Src tyrosine kinase. This study demonstrates the necessity of non-canonical TGF-β1 signaling in leading to pathologic AVIC differentiation. Moreover, we believe that the results of this study suggest 5-HT2B antagonism as a novel therapeutic approach for CAVD that merits further investigation. PMID:22940605

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2011-08-01

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

  7. Regulation of the 5-HT3A receptor-mediated current by alkyl 4-hydroxybenzoates isolated from the seeds of Nelumbo nucifera.

    PubMed

    Youn, Ui Joung; Lee, Jun-Ho; Lee, Yoo Jin; Nam, Joo Won; Bae, Hyunsu; Seo, Eun-Kyoung

    2010-09-01

    Four known alkyl 4-hydroxybenzoates, i.e., methyl 4-hydroxybenzoate (1), ethyl 4-hydroxybenzoate (2), propyl 4-hydroxybenzoate (3), and butyl 4-hydroxybenzoate (4), were isolated from the seeds of Nelumbo nucifera Gaertner (Nymphaeaceae) for the first time. The structures of the isolates were identified by 1D- and 2D-NMR spectroscopy and comparison with published values. The compounds were evaluated for their effects on the 5-HT-stimulated inward current (I(5-HT)) mediated by the human 5-HT(3)A receptors expressed in Xenopus oocytes. Compounds 1 and 2 enhanced the I(5-HT), but 4 reduced it. These results indicate that 4 is an inhibitor of the 5-HT(3)A receptors expressed in Xenopus oocytes.

  8. Regulation of the 5-HT3A receptor-mediated current by alkyl 4-hydroxybenzoates isolated from the seeds of Nelumbo nucifera.

    PubMed

    Youn, Ui Joung; Lee, Jun-Ho; Lee, Yoo Jin; Nam, Joo Won; Bae, Hyunsu; Seo, Eun-Kyoung

    2010-09-01

    Four known alkyl 4-hydroxybenzoates, i.e., methyl 4-hydroxybenzoate (1), ethyl 4-hydroxybenzoate (2), propyl 4-hydroxybenzoate (3), and butyl 4-hydroxybenzoate (4), were isolated from the seeds of Nelumbo nucifera Gaertner (Nymphaeaceae) for the first time. The structures of the isolates were identified by 1D- and 2D-NMR spectroscopy and comparison with published values. The compounds were evaluated for their effects on the 5-HT-stimulated inward current (I(5-HT)) mediated by the human 5-HT(3)A receptors expressed in Xenopus oocytes. Compounds 1 and 2 enhanced the I(5-HT), but 4 reduced it. These results indicate that 4 is an inhibitor of the 5-HT(3)A receptors expressed in Xenopus oocytes. PMID:20860031

  9. 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

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

    PubMed Central

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

    2010-01-01

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

  11. Serotonin and the 5-HT7 receptor: the link between hepatocytes, IGF-1 and small intestinal neuroendocrine tumors.

    PubMed

    Svejda, Bernhard; Kidd, Mark; Timberlake, Andrew; Harry, Kathy; Kazberouk, Alexander; Schimmack, Simon; Lawrence, Ben; Pfragner, Roswitha; Modlin, Irvin M

    2013-07-01

    Platelet-derived serotonin (5-HT) is involved in liver regeneration. The liver is also the metastatic site for malignant enterochromaffin (EC) cell "carcinoid" (neuroendocrine) neoplasms, the principal cellular source of 5-HT. We hypothesized that 5-HT produced by metastatic EC cells played a role in the hepatic tumor-microenvironment principally via 5-HT₇ receptor-mediated activation of hepatocyte IGF-1 synthesis and secretion. Using isolated rat hepatocytes, we evaluated 5-HT₇ receptor expression (using PCR, sequencing and western blot). ELISA, cell transfection and western blots delineated 5-HT-mediated signaling pathways (pCREB, AKT and ERK). IGF-1 synthesis/secretion was evaluated using QPCR and ELISA. IGF-1 was tested on small intestinal neuroendocrine neoplasm proliferation, while IGF-1 production and 5-HT₇ expression were examined in an in vivo SCID metastasis model. Our results demonstrated evidence for a functional 5-HT₇ receptor. 5-HT activated cAMP/PKA activity, pCREB (130-205%, P < 0.05) and pERK/pAKT (1.2-1.75, P < 0.05). Signaling was reversed by the 5-HT₇ receptor antagonist SB269970. IGF-1 significantly stimulated proliferation of two small intestinal neuroendocrine neoplasm cell lines (EC₅₀: 7-70 pg/mL) and could be reversed by the small molecule inhibitor BMS-754807. IGF-1 and 5-HT were elevated (40-300×) in peri-tumoral hepatic tissue in nude mice, while 5-HT₇ was increased fourfold compared to sham-operated animals. We conclude that hepatocytes express a cAMP-coupled 5-HT₇ receptor, which, at elevated 5-HT concentrations that occur in liver metastases, signals via CREB/AKT and is linked to IGF-1 synthesis and secretion. Because IGF-1 regulates NEN proliferation, identification of a role for 5-HT₇ in the hepatic metastatic tumor microenvironment suggests the potential for novel therapeutic strategies for amine-producing mid-gut tumors. PMID:23578138

  12. Spinal 5-HT7 receptor activation induces long-lasting phrenic motor facilitation

    PubMed Central

    Hoffman, M S; Mitchell, G S

    2011-01-01

    Abstract Acute intermittent hypoxia elicits a form of serotonin-dependent respiratory plasticity known as phrenic long term facilitation (pLTF). Episodic spinal serotonin-2 (5-HT2) receptor activation on or near phrenic motor neurons is necessary for pLTF. A hallmark of pLTF is the requirement for serotonin-dependent synthesis of brain-derived neurotrophic factor (BDNF), and activation of its high affinity receptor, TrkB. Activation of spinal Gs protein-coupled adenosine 2A receptors (GsPCRs) elicits a unique form of long-lasting phrenic motor facilitation (PMF), but via unique mechanisms (BDNF independent TrkB trans-activation). We hypothesized that other GsPCRs elicit PMF, specifically serotonin-7 (5-HT7) receptors, which are expressed in phrenic motor neurons. Cervical spinal (C4) injections of a selective 5-HT7 receptor agonist, AS-19 (10 μm, 5 μl; 3 × 5 min), in anaesthetized, vagotomized and ventilated male Sprague–Dawley rats elicited long-lasting PMF (>120 min), an effect prevented by pretreatment with a 5-HT7 receptor antagonist (SB 269970; 5 mm, 7 μl). GsPCR activation ‘trans-activates’ TrkB by increasing synthesis of an immature TrkB isoform. Spinal injection of a TrkB inhibitor (k252a) and siRNAs that prevent TrkB (but not BDNF) mRNA translation both blocked 5-HT7 agonist-induced PMF, confirming a requirement for TrkB synthesis and activity. k252a affected late PMF (≥90 min) only. Spinal inhibition of the PI3K/AKT pathway blocked 5-HT7 agonist-induced PMF, whereas MEK/ERK inhibition delayed, but did not block, PMF. An understanding of signalling mechanisms giving rise to PMF may guide development of novel therapeutic strategies to treat ventilatory control disorders associated with respiratory insufficiency, such as spinal injury and motor neuron disease. PMID:21242254

  13. Variation within the serotonin (5-HT) 5-HT2C receptor system aligns with vulnerability to cocaine cue reactivity

    PubMed Central

    Anastasio, N C; Liu, S; Maili, L; Swinford, S E; Lane, S D; Fox, R G; Hamon, S C; Nielsen, D A; Cunningham, K A; Moeller, F G

    2014-01-01

    Cocaine dependence remains a challenging public health problem with relapse cited as a major determinant in its chronicity and severity. Environmental contexts and stimuli become reliably associated with its use leading to durable conditioned responses (‘cue reactivity') that can predict relapse as well as treatment success. Individual variation in the magnitude and influence of cue reactivity over behavior in humans and animals suggest that cue-reactive individuals may be at greater risk for the progression to addiction and/or relapse. In the present translational study, we investigated the contribution of variation in the serotonin (5-HT) 5-HT2C receptor (5-HT2CR) system in individual differences in cocaine cue reactivity in humans and rodents. We found that cocaine-dependent subjects carrying a single nucleotide polymorphism (SNP) in the HTR2C gene that encodes for the conversion of cysteine to serine at codon 23 (Ser23 variant) exhibited significantly higher attentional bias to cocaine cues in the cocaine-word Stroop task than those carrying the Cys23 variant. In a model of individual differences in cocaine cue reactivity in rats, we identified that high cocaine cue reactivity measured as appetitive approach behavior (lever presses reinforced by the discrete cue complex) correlated with lower 5-HT2CR protein expression in the medial prefrontal cortex and blunted sensitivity to the suppressive effects of the selective 5-HT2CR agonist WAY163909. Our translational findings suggest that the functional status of the 5-HT2CR system is a mechanistic factor in the generation of vulnerability to cocaine-associated cues, an observation that opens new avenues for future development of biomarker and therapeutic approaches to suppress relapse in cocaine dependence. PMID:24618688

  14. Relative activities on and uptake by human blood platelets of 5-hydroxytryptamine and several analogues

    PubMed Central

    Born, G. V. R.; Juengjaroen, Kanchana; Michal, F.

    1972-01-01

    1. The specificity of platelet receptor sites for 5-HT uptake and for the rapid morphological change and aggregation was investigated with 5-hydroxy-tryptamine (5-HT) and seventeen analogues as well as with some antagonists of 5-HT. 2. The analogues, with the exception of 5-hydroxy-N'N'-dibutyltryptamine, caused the rapid morphological change in platelets. In concentrations below those needed to produce the agonistic action (viz. 0.05-2.0 μM), these analogues themselves inhibited competitively the shape change caused by 5-HT. 3. The velocity of change in shape caused by 5-HT was reduced in low Na media. 4. Ten analogues produced platelet aggregation; three of these, viz. 5-methoxy-α-methyltryptamine, 5-hydroxy-α-methyltryptamine and 5-hydroxy-N'N'-diisopropyltryptamine), were approximately equipotent with 5-HT. Six analogues did not induce platelet aggregation. 5. All the analogues which prevented the initial change in shape of platelets caused by 5-HT also inhibited its aggregating effect, apparently competitively with low Ki values (0.02-1.6 μM). 6. As with the inhibition of shape change, the inhibition of aggregation shows relatively low structural specificity of the receptor site. 7. Methysergide was a potent inhibitor of shape change and aggregation (Ki∼0.03 μM); imipramine was much less inhibitory (Ki∼5-10 μM). 8. Only one analogue (5-hydroxy-α-methyltryptamine) was taken up like 5-HT by platelets. All the other analogues inhibited the uptake of 5-HT by platelets (Ki=0.2-2.7 μM). 9. Methysergide was a weak inhibitor of 5-HT uptake (Ki∼125 μM) whereas imipramine was very effective (Ki∼0.3 μM). 10. Our results show that the initial change in shape of platelets is required for and precedes aggregation. The structural specificity of the platelet receptor concerned with shape change and aggregation caused by 5-HT appears low whereas the uptake mechanism is a highly specific one. The uptake probably proceeds through more than one step, the

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

    PubMed

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

    2015-10-01

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

  16. 5-HT1A Receptors on Mature Dentate Gyrus Granule Cells are Critical for the Antidepressant Response

    PubMed Central

    Samuels, Benjamin Adam; Anacker, Christoph; Hu, Alice; Levinstein, Marjorie R.; Pickenhagen, Anouchka; Tsetsenis, Theodore; Madroñal, Noelia; Donaldson, Zoe R.; Drew, Liam John; Dranovsky, Alex; Gross, Cornelius T.; Tanaka, Kenji F.; Hen, René

    2015-01-01

    Selective serotonin reuptake inhibitors (SSRIs) are widely used antidepressants, but the mechanisms by which they influence behavior are only partially resolved. Adult hippocampal neurogenesis is necessary for some of the responses to SSRIs, but it is unknown whether the mature dentate gyrus granule cells (mature DG GCs) also contribute. We deleted Serotonin 1A receptor (5HT1AR; a receptor required for the SSRI response) specifically from DG GCs and found that the effects of the SSRI fluoxetine on behavior and the Hypothalamic-Pituitary-Adrenal (HPA) axis were abolished. By contrast, mice lacking 5HT1ARs only in young adult born granule cells (abGCs) showed normal fluoxetine responses. Importantly, 5HT1AR deficient mice engineered to express functional 5HT1ARs only in DG GCs responded to fluoxetine, indicating that 5HT1ARs in DG GCs are sufficient to mediate an antidepressant response. Taken together, these data indicate that both mature DG GCs and young abGCs must be engaged for an antidepressant response. PMID:26389840

  17. Neuromodulation in molluscan smooth muscle: the action of 5-HT, FMRFamide and purine compounds.

    PubMed

    Nelson, I D; Huddart, H

    1994-05-01

    1. The RR, OR, RS and RP muscles of Buccinum did not respond directly to 5-HT, but this monoamine converted their normally tonic ACh responses to fast twitch contractions with lowered tonic force. This action was not accompanied by significant membrane potential changes. 2. Pre-treatment with dibutyryl cAMP potentiated ACh responses and enhanced 5-HT modification of the responses. 3. All muscles responded strongly to FMRFamide with twitch contractions but this was not accompanied by significant membrane potential changes. 4. FMRFamide enhanced ACh contracture force and converted the responses into fast twitch activity. FMRFamide responses were dramatically inhibited by 5-HT with loss of all tonic force and fast twitch activity. 5. While dibutyryl cAMP did not affect FMRFamide responses, the IP3 inhibitor lithium, at very high concentrations, caused a significant diminution of FMRFamide responses. 6. All four muscles were unresponsive to adenosine and ATP but all except the RP responded in a dose-dependent manner to GTP and GTP-gamma-S over the 10(-7) - 10(-4) mol l-1 range. The responses showed moderate fast twitch activity which was unaccompanied by action potential discharges. Guanosine was without effect, except at very high concentrations where it inhibited FMRFamide responses. 7. ACh and GTP acted additively to increase muscle force and to enhance ACh-induced depolarization. Similarly both GTP and GTP-gamma-S acted additively, considerably enhancing FMRFamide responses. 8. It is proposed that 5-HT, FMRFamide and GTP may, via their separate receptors or by possible interaction with ion channels, activate secondary messenger systems to modify the calcium released by ACh-induced depolarization to modulate excitation-contraction coupling and force generation in these muscles.

  18. 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...

  19. 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]…

  20. No contractile effect for 5-HT1D and 5-HT1F receptor agonists in human and bovine cerebral arteries: similarity with human coronary artery

    PubMed Central

    Bouchelet, Isabelle; Case, Bruce; Olivier, André; Hamel, Edith

    2000-01-01

    Using subtype-selective 5-HT1 receptor agonists and/or the 5-HT1 receptor antagonist GR127935, we characterized in vitro the 5-HT receptor that mediates the contraction of human and bovine cerebral arteries. Further, we investigated which sumatriptan-sensitive receptors are present in human coronary artery by reverse-transcriptase polymerase chain reaction (RT–PCR). Agonists with affinity at the 5-HT1B receptor, such as sumatriptan, alniditan and/or IS-159, elicited dose-dependent contraction in both human and bovine cerebral arteries. They behaved as full agonists at the sumatriptan-sensitive 5-HT1 receptors in both species. In contrast, PNU-109291 and LY344864, selective agonists at 5-HT1D and 5-HT1F receptors, respectively, were devoid of any significant vasocontractile activity in cerebral arteries, or did not affect the sumatriptan-induced vasocontraction. The rank order of agonist potency was similar in both species and could be summarized as 5-HT=alniditan>sumatriptan=IS-159>>>PNU-109291=LY344864. In bovine cerebral arteries, the 5-HT1 receptor antagonist GR127935 dose-dependently inhibited the vasoconstrictions elicited by both 5-HT and sumatriptan, with respective pA2 values of 8.0 and 8.6. RT–PCR studies in human coronary arteries showed a strong signal for the 5-HT1B receptor while message for the 5-HT1F receptor was weak and less frequently detected. Expression of 5-HT1D receptor mRNA was not detected in any sample. The present results demonstrate that the triptan-induced contraction in brain vessels is mediated exclusively by the 5-HT1B receptor, which is also present in a majority of human coronary arteries. These results suggest that selective 5-HT1D and 5-HT1F receptor agonists might represent new antimigraine drugs devoid of cerebro- and cardiovascular effects. PMID:10711348

  1. Serotonin acts through 5-HT1 and 5-HT2 receptors to exert biphasic actions on GnRH neuron excitability in the mouse.

    PubMed

    Bhattarai, Janardhan P; Roa, Juan; Herbison, Allan E; Han, Seong Kyu

    2014-02-01

    The effect of serotonin (5-HT) on the electrical excitability of GnRH neurons was examined using gramicidin perforated-patch electrophysiology in transgenic GnRH-green fluorescent protein mice. In diestrous female, the predominant effect of 5-HT was inhibition (70%) with 50% of these cells also exhibiting a late-onset excitation. Responses were dose dependent (EC(50) = 1.2μM) and persisted in the presence of amino acid receptor antagonists and tetrodotoxin, indicating a predominant postsynaptic action of 5-HT. Studies in neonatal, juvenile, peripubertal, and adult mice revealed that 5-HT exerted less potent responses from GnRH neurons with advancing postnatal age in both sexes. In adult male mice, 5-HT exerted less potent hyperpolarizing responses with more excitations compared with females. In addition, adult proestrous female GnRH neurons exhibited reduced inhibition and a complete absence of biphasic hyperpolarization-excitation responses. Studies using 5-HT receptor antagonists demonstrated that the activation of 5-HT(1A) receptors mediated the inhibitory responses, whereas the excitation was mediated by the activation of 5-HT(2A) receptors. The 5-HT-mediated hyperpolarization involved both potassium channels and adenylate cyclase activation, whereas the 5-HT excitation was dependent on protein kinase C. The effects of exogenous 5-HT were replicated using fluoxetine, which enhances endogenous 5-HT levels. These studies demonstrate that 5-HT exerts a biphasic action on most GnRH neurons whereby a fast 5HT(1A)-mediated inhibition occurs alongside a slow 5-HT(2A) excitation. The balance of 5-HT-evoked inhibition vs excitation is developmentally regulated, sexually differentiated, and variable across the estrous cycle and may play a role in regulation of hypothalamic-pituitary-gonadal axis throughout postnatal development.

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

    PubMed Central

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

    2013-01-01

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

  3. 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

  4. Effect of acute and prolonged tianeptine administration on the 5-HT transporter: electrophysiological, biochemical and radioligand binding studies in the rat brain.

    PubMed

    Piñeyro, G; Deveault, L; Blier, P; Dennis, T; de Montigny, C

    1995-02-01

    In the present study, in vivo extracellular unitary recordings, in vitro [3H]5-HT uptake and [3H]cyanoimipramine binding assays were used to assess the effect of acute and prolonged administration of the putative antidepressant tianeptine, on the 5-hydroxytryptamine (5-HT) transporter. Microiontophoretic application of tianeptine onto dorsal hippocampus CA3 pyramidal neurons, as well as its intravenous administration (2 mg/kg), increased their firing frequency. Following intracerebroventricular administration of 5,7-dihydroxytryptamine, the activation induced by the microiontophoretic application of tianeptine remained unchanged, thus suggesting that the 5-HT carrier is not involved in this effect. Furthermore, in spite of its activating effect on CA3 pyramidal neuron firing frequency, the intravenous administration of tianeptine did not alter the time of recovery of these neurons from microiontophoretic applications of 5-HT, an index of 5-HT uptake activity. In keeping with this observation, the acute administration of tianeptine did not change the effectiveness of the 5-HT reuptake blocker paroxetine (1 mg/kg, i.v.) in prolonging the suppressant effect of microiontophoretically-applied 5-HT. However, in rats that had received tianeptine for 14 days (20 mg/kg/day, s.c.), the recovery time from the suppressant effect of microiontophoretic applications of 5-HT was reduced by 40% and the effectiveness of paroxetine (1 mg/kg, i.v.) was decreased. These effects were no longer observed following a 48 h washout period. In a second series of experiments, the ability of tianeptine to interfere with the uptake blocking capacity of paroxetine was assessed in vitro, using hippocampal slices obtained from rats that had been treated with tianeptine for 14 days (20 mg/kg/day, s.c.; by minipump).(ABSTRACT TRUNCATED AT 250 WORDS)

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

    PubMed

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

    2016-01-01

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

  6. 5-HT2A receptors control body temperature in mice during LPS-induced inflammation via regulation of NO production.

    PubMed

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

    2016-01-01

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

  7. Fluoxetine potentiation of methylphenidate-induced gene regulation in striatal output pathways: potential role for 5-HT1B receptor.

    PubMed

    Van Waes, Vincent; Ehrlich, Sarah; Beverley, Joel A; Steiner, Heinz

    2015-02-01

    Drug combinations that include the psychostimulant methylphenidate plus a selective serotonin reuptake inhibitor (SSRI) such as fluoxetine are increasingly used in children and adolescents. For example, this combination is indicated in the treatment of attention-deficit/hyperactivity disorder and depression comorbidity and other mental disorders. Such co-exposure also occurs in patients on SSRIs who use methylphenidate as a cognitive enhancer. The neurobiological consequences of these drug combinations are poorly understood. Methylphenidate alone can produce gene regulation effects that mimic addiction-related gene regulation by cocaine, consistent with its moderate addiction liability. We have previously shown that combining SSRIs with methylphenidate potentiates methylphenidate-induced gene regulation in the striatum. The present study investigated which striatal output pathways are affected by the methylphenidate + fluoxetine combination, by assessing effects on pathway-specific neuropeptide markers, and which serotonin receptor subtypes may mediate these effects. Our results demonstrate that a 5-day repeated treatment with fluoxetine (5 mg/kg) potentiates methylphenidate (5 mg/kg)-induced expression of both dynorphin (direct pathway marker) and enkephalin (indirect pathway). These changes were accompanied by correlated increases in the expression of the 5-HT1B, but not 5-HT2C, serotonin receptor in the same striatal regions. A further study showed that the 5-HT1B receptor agonist CP94253 (3-10 mg/kg) mimics the fluoxetine potentiation of methylphenidate-induced gene regulation. These findings suggest a role for the 5-HT1B receptor in the fluoxetine effects on striatal gene regulation. Given that 5-HT1B receptors are known to facilitate addiction-related gene regulation and behavior, our results suggest that SSRIs may enhance the addiction liability of methylphenidate by increasing 5-HT1B receptor signaling.

  8. The role of 5-HT1A receptors in mediating acute negative effects of antidepressants: implications in pediatric depression

    PubMed Central

    Rahn, K A; Cao, Y-J; Hendrix, C W; Kaplin, A I

    2015-01-01

    Acute antidepressant exposure elevates the frequency of impulsive behavior and suicidal thoughts in children and adolescents with major depressive disorder (MDD). Long-term antidepressant treatment, however, is beneficial for pediatric MDD, so it is necessary to explore novel treatments that prevent the potentially dangerous consequences of acute antidepressant initiation. In the present study, a treatment strategy designed to reverse the acute negative behavioral effects of antidepressants was tested in rodents. Co-administration of the 5-HT1A receptor (5-HT1AR) antagonist WAY-100635 reversed the negative effects of acute fluoxetine, a serotonin reuptake inhibitor, but not reboxetine, a norepinephrine reuptake inhibitor, supporting the involvement of 5-HT1AR in mediating the negative consequences of acute selective serotonin reuptake inhibitor (SSRI) treatment. No 5-HT1AR antagonists are currently approved for use in pediatric populations, so alternative strategies should be explored. One such strategy was suggested based on the hypothesis that the rate of 5-HT1AR activation and the subsequent inhibition of serotonergic neuron activity caused by acute SSRI administration is proportional to the loading rate of an antidepressant. Existing pharmacological data were examined, and significant correlations were observed between the half-life of antidepressants and the rate of suicide-related events (SREs). Specifically, antidepressants with longer half-lives have lower rates of SREs. On the basis of these data, novel dosing strategies were developed for five antidepressants to mimic the pharmacological profile of the antidepressant with the longest half-life, fluoxetine. These dosing strategies could be used to decrease the rate of SREs associated with acute antidepressant treatment in pediatric MDD until an improved pharmacological treatment is developed. PMID:25942044

  9. The 5-HT4 receptor: molecular cloning and pharmacological characterization of two splice variants.

    PubMed Central

    Gerald, C; Adham, N; Kao, H T; Olsen, M A; Laz, T M; Schechter, L E; Bard, J A; Vaysse, P J; Hartig, P R; Branchek, T A

    1995-01-01

    Molecular cloning efforts have provided primary amino acid sequence and signal transduction data for a large collection of serotonin receptor subtypes. These include five 5-HT1-like receptors, three 5-HT2 receptors, one 5-HT3 receptor, two 5-HT5 receptors, one 5-HT6 receptor and one 5-HT7 receptor. Molecular biological information on the 5-HT4 receptor is notably absent from this list. We now report the cloning of the pharmacologically defined 5-HT4 receptor. Using degenerate oligonucleotide primers, we identified a rat brain PCR fragment which encoded a '5-HT receptor-like' amino acid sequence. The corresponding full length cDNA was isolated from a rat brain cDNA library. Transiently expressed in COS-7 cells, this receptor stimulates adenylyl cyclase activity and is sensitive to the benzamide derivative cisapride. The response is also blocked by ICS-205930. Interestingly, we isolated two splice variants of the receptor, 5-HT4L and 5-HT4S, differing in the length and sequence of their C-termini. In rat brain, the 5-HT4S transcripts are restricted to the striatum, but the 5-HT4L transcripts are expressed throughout the brain, except in the cerebellum where it was barely detectable. In peripheral tissues, differential expression was also observed in the atrium of the heart where only the 5-HT4S isoform was detectable. Images PMID:7796807

  10. Excitation of rat colonic afferent fibres by 5-HT3 receptors

    PubMed Central

    Hicks, Gareth A; Coldwell, Jonathan R; Schindler, Marcus; Bland Ward, Philip A; Jenkins, David; Lynn, Penny A; Humphrey, Patrick P A; Blackshaw, L Ashley

    2002-01-01

    The gastrointestinal tract contains most of the body's 5-hydroxytryptamine (5-HT) and releases large amounts after meals or exposure to toxins. Increased 5-HT release occurs in patients with irritable bowel syndrome (IBS) and their peak plasma 5-HT levels correlate with pain episodes. 5-HT3 receptor antagonists reduce symptoms of IBS clinically, but their site of action is unclear and the potential for other therapeutic targets is unexplored. Here we investigated effects of 5-HT on sensory afferents from the colon and the expression of 5-HT3 receptors on their cell bodies in the dorsal root ganglia (DRG). Distal colon, inferior mesenteric ganglion and the lumbar splanchnic nerve bundle (LSN) were placed in a specialized organ bath. Eighty-six single fibres were recorded from the LSN. Three classes of primary afferents were found: 70 high-threshold serosal afferents, four low-threshold muscular afferents and 12 mucosal afferents. Afferent cell bodies were retrogradely labelled from the distal colon to the lumbar DRG, where they were processed for 5-HT3 receptor-like immunoreactivity. Fifty-six percent of colonic afferents responded to 5-HT (between 10−6 and 10−3 M) and 30 % responded to the selective 5-HT3 agonist, 2-methyl-5-HT (between 10−6 and 10−2 M). Responses to 2-methyl-5-HT were blocked by the 5-HT3 receptor antagonist alosetron (2 × 10−7 M), whereas responses to 5-HT were only partly inhibited. Twenty-six percent of L1 DRG cell bodies retrogradely labelled from the colon displayed 5-HT3 receptor-like immunoreactivity. We conclude that colonic sensory neurones expressing 5-HT3 receptors also functionally express the receptors at their peripheral endings. Our data reveal actions of 5-HT on colonic afferent endings via both 5-HT3 and non-5-HT3 receptors. PMID:12411529

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

    PubMed Central

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

    1996-01-01

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

  12. 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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2016-09-01

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

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

    PubMed

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

    2016-09-01

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

  18. Effects of ginger constituents on the gastrointestinal tract: role of cholinergic M3 and serotonergic 5-HT3 and 5-HT4 receptors.

    PubMed

    Pertz, Heinz H; Lehmann, Jochen; Roth-Ehrang, René; Elz, Sigurd

    2011-07-01

    The herbal drug ginger (Zingiber officinale Roscoe) may be effective for treating nausea, vomiting, and gastric hypomotility. In these conditions, cholinergic M (3) receptors and serotonergic 5-HT (3) and 5-HT (4) receptors are involved. The major chemical constituents of ginger are [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-shogaol. We studied the interaction of [6]-gingerol, [8]-gingerol, [10]-gingerol (racemates), and [6]-shogaol with guinea pig M (3) receptors, guinea pig 5-HT (3) receptors, and rat 5-HT (4) receptors. In whole segments of guinea pig ileum (bioassay for contractile M (3) receptors), [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-shogaol slightly but significantly depressed the maximal carbachol response at an antagonist concentration of 10 µM. In the guinea pig myenteric plexus preparation (bioassay for contractile 5-HT (3) receptors), 5-HT maximal responses were depressed by [10]-gingerol from 93 ± 3 % to 65 ± 6 % at an antagonist concentration of 3 µM and to 48 ± 3 % at an antagonist concentration of 5 µM following desensitization of 5-HT (4) receptors and blockade of 5-HT (1) and 5-HT (2) receptors. [6]-Shogaol (3 µM) induced depression to 61 ± 3 %. In rat esophageal tunica muscularis mucosae (bioassay for relaxant 5-HT (4) receptors), [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-shogaol (2-6.3 µM) showed no agonist effects. The maximal 5-HT response remained unaffected in the presence of the compounds. It is concluded that the efficiency of ginger in reducing nausea and vomiting may be based on a weak inhibitory effect of gingerols and shogaols at M (3) and 5-HT (3) receptors. 5-HT (4) receptors, which play a role in gastroduodenal motility, appear not to be involved in the action of these compounds. PMID:21305447

  19. The involvement of medial septum 5-HT1 and 5-HT2 receptors on ACPA-induced memory consolidation deficit: possible role of TRPC3, TRPC6 and TRPV2.

    PubMed

    Najar, Farzaneh; Nasehi, Mohammad; Haeri-Rohani, Seyed-Ali; Zarrindast, Mohammad-Reza

    2015-11-01

    The present study evaluates the roles of serotonergic receptors of the medial septum on amnesia induced by arachidonylcyclopropylamide (ACPA; as selective cannabinoid CB1 receptor agonist) in adult male Wistar rats. Cannulae were implanted in the medial septum of the brain of the rats. The animals were trained in a passive avoidance learning apparatus, and were tested 24 hours after training for step-through latency. Results indicated that post-training medial septum administration of CP94253 (5-HT1B/1D receptor agonist) and cinancerine (as 5-HT2 receptor antagonist) reduced the step-through latency showing an amnesic response, while GR127935 (5-HT1B/1D receptor antagonist) and αm5htm (as 5-HT2A/2B/2D receptor agonist) did not alter memory consolidation by themselves. On continuing the test, the results showed that CP94253 increased and GR127935 did not alter ACPA (0.02 µg/rat)-induced memory impairment, respectively. Other data indicated that αm5htm induced a modulatory effect, while cinancerine restored ACPA-induced amnesia. Using SKF-96365 (inhibitor of transient receptor potential TRPC3/6 and TRPV2 channels) demonstrated that TRPC3, TRPC3 and TRPV2 channels have a significant role, according to our results. PMID:26464456

  20. 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

  1. 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

  2. Anxiolytic profile of HG1, a 5-HT-moduline antagonist, in three mouse models of anxiety.

    PubMed

    Clénet, Florence; Hascoët, Martine; Fillion, Gilles; Galons, Hervé; Bourin, Michel

    2004-12-01

    HG1 is a new 5-HT-moduline antagonist which is itself an endogenous tetrapeptide specifically acting as an antagonist of 5-HT(1B) auto- and heteroreceptors. Blockade of endogenous 5-HT-moduline might provoke anxiolysis, so it could be a new therapeutic target in anxiety disorders. The aim of our study was to examine the effects of HG1 in three mouse models of anxiety: the four plates test (FPT), the black and white (B&W) model and the elevated plus maze (EPM). Male Swiss mice were intraperitoneally and acutely administered HG1 at the doses of 8, 16, 32 and 64 mg/kg. In these three tests, HG1 exhibited an anxiolytic profile similar to that of diazepam, the referential benzodiazepine compound, without affecting locomotor activity. In the three models used, HG1 was as efficient as benzodiazepine and may consequently exert its anxiolytic effects via the GABA-ergic system. We cannot exclude that it might also act through 5-HT receptors and rather have the profile of a selective serotonin reuptake inhibitor.

  3. Serotonin 5-HT3 Receptor-Mediated Vomiting Occurs via the Activation of Ca2+/CaMKII-Dependent ERK1/2 Signaling in the Least Shrew (Cryptotis parva)

    PubMed Central

    Zhong, Weixia; Hutchinson, Tarun E.; Chebolu, Seetha; Darmani, Nissar A.

    2014-01-01

    Stimulation of 5-HT3 receptors (5-HT3Rs) by 2-methylserotonin (2-Me-5-HT), a selective 5-HT3 receptor agonist, can induce vomiting. However, downstream signaling pathways for the induced emesis remain unknown. The 5-HT3R channel has high permeability to extracellular calcium (Ca2+) and upon stimulation allows increased Ca2+ influx. We examined the contribution of Ca2+/calmodulin-dependent protein kinase IIα (Ca2+/CaMKIIα), interaction of 5-HT3R with calmodulin, and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling to 2-Me-5-HT-induced emesis in the least shrew. Using fluo-4 AM dye, we found that 2-Me-5-HT augments intracellular Ca2+ levels in brainstem slices and that the selective 5-HT3R antagonist palonosetron, can abolish the induced Ca2+ signaling. Pre-treatment of shrews with either: i) amlodipine, an antagonist of L-type Ca2+ channels present on the cell membrane; ii) dantrolene, an inhibitor of ryanodine receptors (RyRs) Ca2+-release channels located on the endoplasmic reticulum (ER); iii) a combination of their less-effective doses; or iv) inhibitors of CaMKII (KN93) and ERK1/2 (PD98059); dose-dependently suppressed emesis caused by 2-Me-5-HT. Administration of 2-Me-5-HT also significantly: i) enhanced the interaction of 5-HT3R with calmodulin in the brainstem as revealed by immunoprecipitation, as well as their colocalization in the area postrema (brainstem) and small intestine by immunohistochemistry; and ii) activated CaMKIIα in brainstem and in isolated enterochromaffin cells of the small intestine as shown by Western blot and immunocytochemistry. These effects were suppressed by palonosetron. 2-Me-5-HT also activated ERK1/2 in brainstem, which was abrogated by palonosetron, KN93, PD98059, amlodipine, dantrolene, or a combination of amlodipine plus dantrolene. However, blockade of ER inositol-1, 4, 5-triphosphate receptors by 2-APB, had no significant effect on the discussed behavioral and biochemical parameters. This study demonstrates

  4. Functional Status of the Serotonin 5-HT2C Receptor (5-HT2CR) Drives Interlocked Phenotypes that Precipitate Relapse-Like Behaviors in Cocaine Dependence

    PubMed Central

    Anastasio, Noelle C; Stutz, Sonja J; Fox, Robert G; Sears, Robert M; Emeson, Ronald B; DiLeone, Ralph J; O'Neil, Richard T; Fink, Latham H; Li, Dingge; Green, Thomas A; Gerard Moeller, F; Cunningham, Kathryn A

    2014-01-01

    Relapse vulnerability in cocaine dependence is rooted in genetic and environmental determinants, and propelled by both impulsivity and the responsivity to cocaine-linked cues (‘cue reactivity'). The serotonin (5-hydroxytryptamine, 5-HT) 5-HT2C receptor (5-HT2CR) within the medial prefrontal cortex (mPFC) is uniquely poised to serve as a strategic nexus to mechanistically control these behaviors. The 5-HT2CR functional capacity is regulated by a number of factors including availability of active membrane receptor pools, the composition of the 5-HT2CR macromolecular protein complex, and editing of the 5-HT2CR pre-mRNA. The one-choice serial reaction time (1-CSRT) task was used to identify impulsive action phenotypes in an outbred rat population before cocaine self-administration and assessment of cue reactivity in the form of lever presses reinforced by the cocaine-associated discrete cue complex during forced abstinence. The 1-CSRT task reliably and reproducibly identified high impulsive (HI) and low impulsive (LI) action phenotypes; HI action predicted high cue reactivity. Lower cortical 5-HT2CR membrane protein levels concomitant with higher levels of 5-HT2CR:postsynaptic density 95 complex distinguished HI rats from LI rats. The frequency of edited 5-HT2CR mRNA variants was elevated with the prediction that the protein population in HI rats favors those isoforms linked to reduced signaling capacity. Genetic loss of the mPFC 5-HT2CR induced aggregate impulsive action/cue reactivity, suggesting that depressed cortical 5-HT2CR tone confers vulnerability to these interlocked behaviors. Thus, impulsive action and cue reactivity appear to neuromechanistically overlap in rodents, with the 5-HT2CR functional status acting as a neural rheostat to regulate, in part, the intersection between these vulnerability behaviors. PMID:23939424

  5. 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.

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

    PubMed

    Redrobe, J P; Bourin, M

    1998-08-01

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

  7. 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.

  8. Modulation of brainstem 5-HT1C receptors by serotonergic drugs in the rat.

    PubMed

    Pranzatelli, M R; Tailor, P T

    1994-10-01

    1. The sparse population of brainstem 5-hydroxytryptamine1C (5-HT1C) (also called 5-HT2C) receptors has received little attention despite its possible role in the serotonin syndrome and 5-HT-mediated shaking behavior. We characterized [3H]mesulergine binding in rat brainstem and, to determine if brainstem 5-HT1C sites respond to serotonergic manipulations, performed saturation studies of [3H]mesulergine binding in brainstem from rats treated chronically with 11 different 5-HT1C/2 agonists and antagonists. 2. In competition studies in vitro, the rank order of drug potency was most compatible with a 5-HT1C receptor binding site: mianserin, 5-HT, cinanserin, 1-(3-chlorophenyl)piperazine (m-CPP), 1-(2-5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), MDL 100,907, RU 24969, 5-carboxamidotryptamine (5-CT), 8-OH-DPAT, MDL 72,222. 3. Chronic treatment with the agonists quipazine and trifluoromethylphenylpiperazine (TFMPP) and the antagonists ritanserin and methiothepin significantly down-regulated brainstem 5-HT1C sites, which were 65% of [3H]mesulergine-labeled sites in brainstem. Only metergoline and ritanserin significantly increased pKD. 4. Chronic treatment in vivo with DOI, m-CPP, mianserin, methysergide, spiperone, cyproheptadine, and metergoline had no significant effect on BMAX at the dose studied. 5. These data suggest similarities in the regulation of 5-HT1C and 5-HT2 sites at which both 5-HT1C 2 agonists and antagonists also induce receptor down-regulation. 6. 5-HT1C/2 agonists and antagonists that did not down-regulate brainstem 5-HT1C sites may be more active in vivo at 5-HT2 sites, at 5-HT1C sites in other brain regions, have effects on 5-HT1C receptors not detectable at the recognition site, or differ for pharmacokinetic reasons.

  9. Interaction of 5-HT1B/D ligands with recombinant h 5-HT1A receptors: intrinsic activity and modulation by G-protein activation state.

    PubMed

    Pauwels, P J; Palmier, C; Dupuis, D S; Colpaert, F C

    1998-05-01

    Many 5-HT1B/D receptor ligands have affinity for 5-HT1A receptors. In the present study, the intrinsic activity of a series of 5-HT1B/D ligands was investigated at human 5-HT1A (h 5-HT1A) receptors by measuring G-protein activation in recombinant C6-glial and HeLa membranes, using agonist-stimulated [35S]GTPgammaS binding. In these two membrane preparations, the density of h 5-HT1A receptors (i.e., 246 to 320 fmol mg(-1) protein) and of their G-proteins, and the receptor: G-protein density ratio (0.08 to 0.18) appeared to be similar. It was found that: (i) the maximal [35S]GTPgammaS binding responses induced by the 5-HT1B/D receptor ligands in the HeLa preparation at 30 microM GDP were comparable to that of the native agonist 5-HT; (ii) as compared to 5-HT (1.00), similar potencies but lower maximal responses were observed in the C6-glial preparation at 0.3 microM GDP for zolmitriptan (0.89), dihydroergotamine (0.81), rizatriptan (0.71), CP122638 (0.69), naratriptan (0.60) and sumatriptan (0.53); and that (iii) maximal [35S]GTPgammaS binding responses induced by 5-HT1B/D ligands in the C6-glial preparation were either unaffected or significantly enhanced by increasing the GDP concentration from 0.3 to 30 microM and higher concentrations. These features differ from those observed with 5-HT1A receptor agonists; the latter display the same rank order of potency and efficacy in both membrane preparations, and increasing the amount of GDP with C6-glial membranes results in an attenuation of both the agonist's maximal effect and the apparent potency of partial agonists. The differential regulation of 5-HT1A and 5-HT1B/D agonist responses by GDP suggests that different G-protein subtypes are involved upon 5-HT1A receptor activation by 5-HT1A and 5-HT1B/D agonists. PMID:9650800

  10. 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...

  11. 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

  12. GPER1 stimulation alters posttranslational modification of RGSz1 and induces desensitization of 5-HT1A receptor signaling in the rat hypothalamus

    PubMed Central

    McAllister, Carrie E; Mi, Zhen; Mure, Minae; Li, Qian; Muma, Nancy A

    2014-01-01

    Hyperactivity of the hypothalamic-pituitary-adrenal axis is a consistent biological characteristic of depression and response normalization coincides with clinical responsiveness to antidepressant medications. Desensitization of serotonin 1A receptor (5-HT1AR) signaling in the hypothalamic paraventricular nucleus (PVN) follows selective serotonin reuptake inhibitor (SSRI) antidepressant treatment and contributes to the antidepressant response. Estradiol alone produces a partial desensitization of 5-HT1AR signaling, and synergizes with SSRIs to result in a complete and more rapid desensitization than with SSRIs alone as measured by a decrease in the oxytocin and adrenocorticotrophic hormone(ACTH) responses to 5-HT1AR stimulation. G protein-coupled estrogen receptor1 (GPER1) is necessary for estradiol-induced desensitization of 5-HT1AR signaling, although the underlying mechanisms are still unclear. We now find that stimulation of GPER1 with the selective agonist G-1 and non-selective stimulation of estrogen receptors dramatically alter isoform expression of a key component of the 5-HT1AR signaling pathway, RGSz1, a GTPase activating protein selective for Gαz, the Gα subunit necessary for 5-HT1AR-mediated hormone release. RGSz1 isoforms are differentially glycosylated, SUMOylated, and phosphorylated, and differentially distributed in subcellular organelles. High molecular weight RGSz1 is SUMOylated and glycosylated, localized to the detergent-resistant microdomain (DRM) of the cell membrane, and increased by estradiol and G-1 treatment. Because activated Gαz also localizes to the DRM, increased DRM-localized RGSz1 by estradiol and G-1could reduce Gαz activity, functionally uncoupling 5-HT1AR signaling. Peripheral G-1 treatment produced partial reduction in oxytocin and ACTH responses to 5-HT1AR-stimulation similar to direct injections into the PVN. Together, these results identify GPER1 and RGSz1 as novel targets for the treatment of depression. PMID:25402859

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

    PubMed

    Wolff, M C; Leander, J D

    2000-08-01

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

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

    PubMed

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

    2014-01-01

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

  15. The effect of 5-HT1A receptor agonists on locomotor activity in the guinea-pig.

    PubMed Central

    Evenden, J. L.

    1994-01-01

    1. The present study examined the effects of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), flesinoxan, ipsapirone and buspirone, all agonists at the 5-HT1A receptor, on the locomotor activity of guinea-pigs. The effects of these drugs were contrasted with those of the non-selective 5-HT agonist, 5-methoxy-N,N-dimethyl tryptamine (5-MeO-DMT) and the dopamine D2 antagonist, raclopride. 2. 8-OH-DPAT, flesinoxan and 5-MeO-DMT markedly increased the locomotor activity of naive, unhabituated guinea-pigs in a dose-dependent manner. Buspirone also did so, although to a lesser extent and for a shorter time. The doses at which this effect was seen were higher than those normally employed in rats. Ipsapirone and raclopride had no significant effects on locomotor activity. 3. The locomotor activity increasing effect of 1.0 mg kg-1 8-OH-DPAT was blocked by the selective 5-HT1A antagonist (S)-UH-301 (3.0 and 10.0 mg kg-1), but not by (-)-alprenolol (15.0 mg kg-1). Ipsapirone (30.0 mg kg-1) and raclopride (3.0 mg kg-1) antagonized 8-OH-DPAT-induced locomotor activity but only to a small extent. The 5-HT reuptake inhibitor, zimelidine (10.0 mg kg-1) had no effect. 4. The effect of the 5-HT1A agonists in the guinea-pig contrasts with the effects of 8-OH-DPAT on the locomotor activity of unhabituated rats and mice tested in the same apparatus, but are similar to the effects of 8-OH-DPAT on habituated rats, which show a low baseline of activity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7921613

  16. 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

    2015-12-01

    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.

  17. 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

    2015-12-01

    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. PMID:26631478

  18. Characterisation of the 5-HT receptor binding profile of eletriptan and kinetics of [3H]eletriptan binding at human 5-HT1B and 5-HT1D receptors.

    PubMed

    Napier, C; Stewart, M; Melrose, H; Hopkins, B; McHarg, A; Wallis, R

    1999-03-01

    The affinity of eletriptan ((R)-3-(1-methyl-2-pyrrolidinylmethyl)-5-[2-(phenylsulphonyl )ethyl]-1H-indole) for a range of 5-HT receptors was compared to values obtained for other 5-HT1B/1D receptor agonists known to be effective in the treatment of migraine. Eletriptan, like sumatriptan, zolmitriptan, naratriptan and rizatriptan had highest affinity for the human 5-HT1B, 5-HT1D and putative 5-ht1f receptor. Kinetic studies comparing the binding of [3H]eletriptan and [3H]sumatriptan to the human recombinant 5-HT1B and 5-HT1D receptors expressed in HeLa cells revealed that both radioligands bound with high specificity (>90%) and reached equilibrium within 10-15 min. However, [3H]eletriptan had over 6-fold higher affinity than [3H]sumatriptan at the 5-HT1D receptor (K(D)): 0.92 and 6.58 nM, respectively) and over 3-fold higher affinity than [3H]sumatriptan at the 5-HT1B receptor (K(D): 3.14 and 11.07 nM, respectively). Association and dissociation rates for both radioligands could only be accurately determined at the 5-HT1D receptor and then only at 4 degrees C. At this temperature, [3H]eletriptan had a significantly (P<0.05) faster association rate (K(on) 0.249 min(-1) nM(-1)) than [3H]sumatriptan (K(on) 0.024 min(-1) nM(-1)) and a significantly (P<0.05) slower off-rate (K(off) 0.027 min(-1) compared to 0.037 min(-1) for [3H]sumatriptan). These data indicate that eletriptan is a potent ligand at the human 5-HT1B, 5-HT1D, and 5-ht1f receptors and are consistent with its potent vasoconstrictor activity and use as a drug for the acute treatment of migraine headache. PMID:10193663

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

    PubMed

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

    2016-07-15

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

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

    PubMed

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

    1999-08-01

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

  1. 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.

  2. 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.

  3. Down-regulation of 5-HT1B and 5-HT1D receptors inhibits proliferation, clonogenicity and invasion of human pancreatic cancer cells.

    PubMed

    Gurbuz, Nilgun; Ashour, Ahmed A; Alpay, S Neslihan; Ozpolat, Bulent

    2014-01-01

    Pancreatic ductal adenocarcinoma is characterized by extensive local tumor invasion, metastasis and early systemic dissemination. The vast majority of pancreatic cancer (PaCa) patients already have metastatic complications at the time of diagnosis, and the death rate of this lethal type of cancer has increased over the past decades. Thus, efforts at identifying novel molecularly targeted therapies are priorities. Recent studies have suggested that serotonin (5-HT) contributes to the tumor growth in a variety of cancers including prostate, colon, bladder and liver cancer. However, there is lack of evidence about the impact of 5-HT receptors on promoting pancreatic cancer. Having considered the role of 5-HT-1 receptors, especially 5-HT1B and 5-HT1D subtypes in different types of malignancies, the aim of this study was to investigate the role of 5-HT1B and 5-HT1D receptors in PaCa growth and progression and analyze their potential as cytotoxic targets. We found that knockdown of 5-HT1B and 5-HT1D receptors expression, using specific small interfering RNA (siRNA), induced significant inhibition of proliferation and clonogenicity of PaCa cells. Also, it significantly suppressed PaCa cells invasion and reduced the activity of uPAR/MMP-2 signaling and Integrin/Src/Fak-mediated signaling, as integral tumor cell pathways associated with invasion, migration, adhesion, and proliferation. Moreover, targeting 5-HT1B and 5-HT1D receptors down-regulates zinc finger ZEB1 and Snail proteins, the hallmarks transcription factors regulating epithelial-mesenchymal transition (EMT), concomitantly with up-regulating of claudin-1 and E-Cadherin. In conclusion, our data suggests that 5-HT1B- and 5-HT1D- mediated signaling play an important role in the regulation of the proliferative and invasive phenotype of PaCa. It also highlights the therapeutic potential of targeting of 5-HT1B/1D receptors in the treatment of PaCa, and opens a new avenue for biomarkers identification, and valuable new

  4. Down-regulation of 5-HT1B and 5-HT1D receptors inhibits proliferation, clonogenicity and invasion of human pancreatic cancer cells.

    PubMed

    Gurbuz, Nilgun; Ashour, Ahmed A; Alpay, S Neslihan; Ozpolat, Bulent

    2014-01-01

    Pancreatic ductal adenocarcinoma is characterized by extensive local tumor invasion, metastasis and early systemic dissemination. The vast majority of pancreatic cancer (PaCa) patients already have metastatic complications at the time of diagnosis, and the death rate of this lethal type of cancer has increased over the past decades. Thus, efforts at identifying novel molecularly targeted therapies are priorities. Recent studies have suggested that serotonin (5-HT) contributes to the tumor growth in a variety of cancers including prostate, colon, bladder and liver cancer. However, there is lack of evidence about the impact of 5-HT receptors on promoting pancreatic cancer. Having considered the role of 5-HT-1 receptors, especially 5-HT1B and 5-HT1D subtypes in different types of malignancies, the aim of this study was to investigate the role of 5-HT1B and 5-HT1D receptors in PaCa growth and progression and analyze their potential as cytotoxic targets. We found that knockdown of 5-HT1B and 5-HT1D receptors expression, using specific small interfering RNA (siRNA), induced significant inhibition of proliferation and clonogenicity of PaCa cells. Also, it significantly suppressed PaCa cells invasion and reduced the activity of uPAR/MMP-2 signaling and Integrin/Src/Fak-mediated signaling, as integral tumor cell pathways associated with invasion, migration, adhesion, and proliferation. Moreover, targeting 5-HT1B and 5-HT1D receptors down-regulates zinc finger ZEB1 and Snail proteins, the hallmarks transcription factors regulating epithelial-mesenchymal transition (EMT), concomitantly with up-regulating of claudin-1 and E-Cadherin. In conclusion, our data suggests that 5-HT1B- and 5-HT1D-mediated signaling play an important role in the regulation of the proliferative and invasive phenotype of PaCa. It also highlights the therapeutic potential of targeting of 5-HT1B/1D receptors in the treatment of PaCa, and opens a new avenue for biomarkers identification, and valuable new

  5. 5-HT1A/1B, 5-HT6, and 5-HT7 serotonergic receptors recruitment in tonic-clonic seizure-induced antinociception: role of dorsal raphe nucleus.

    PubMed

    Freitas, Renato Leonardo; Ferreira, Célio Marcos dos Reis; Urbina, Maria Angélica Castiblanco; Mariño, Andrés Uribe; Carvalho, Andressa Daiane; Butera, Giuseppe; de Oliveira, Ana Maria; Coimbra, Norberto Cysne

    2009-05-01

    Pharmacological studies have been focused on the involvement of different neural pathways in the organization of antinociception that follows tonic-clonic seizures, including 5-hydroxytryptamine (5-HT)-, norepinephrine-, acetylcholine- and endogenous opioid peptide-mediated mechanisms, giving rise to more in-depth comprehension of this interesting post-ictal antinociceptive phenomenon. The present work investigated the involvement of 5-HT(1A/1B), 5-HT(6), and 5-HT(7) serotonergic receptors through peripheral pretreatment with methiothepin at doses of 0.5, 1.0, 2.0 and 3.0 mg/kg in the organization of the post-ictal antinociception elicited by pharmacologically (with pentylenetetrazole at 64 mg/kg)-induced tonic-clonic seizures. Methiothepin at 1.0 mg/kg blocked the post-ictal antinociception recorded after the end of seizures, whereas doses of 2.0 and 3.0 mg/kg potentiated the post-ictal antinociception. The nociceptive thresholds were kept higher than those of the control group. However, when the same 5-hydroxytryptamine receptors antagonist was microinjected (at 1.0, 3.0 and 5.0 microg/0.2 microL) in the dorsal raphe nucleus, a mesencephalic structure rich in serotonergic neurons and 5-HT receptors, the post-ictal hypo-analgesia was consistently antagonized. The present findings suggest a dual effect of methiothepin, characterized by a disinhibitory effect on the post-ictal antinociception when peripherally administered (possibly due to an antagonism of pre-synaptic 5-HT(1A) serotonergic autoreceptors in the pain endogenous inhibitory system) and an inhibitory effect (possibly due to a DRN post-synaptic 5-HT(1B), 5-HT(6), and 5-HT(7) serotonergic receptors blockade) when centrally administered. The present data also suggest that serotonin-mediated mechanisms of the dorsal raphe nucleus exert a key-role in the modulation of the post-ictal antinociception.

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

    PubMed Central

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

    2014-01-01

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

  7. The Role of 5-HT3 Receptors in Signaling from Taste Buds to Nerves

    PubMed Central

    Vandenbeuch, Aurelie; Voigt, Anja; Meyerhof, Wolfgang; Kinnamon, Sue C.; Finger, Thomas E.

    2015-01-01

    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-HT3A 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-HT3A 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. SIGNIFICANCE STATEMENT Historically, serotonin (5-hydroxytryptamine; 5-HT) has been described as a candidate neurotransmitter in the gustatory system and recent studies show that type III taste receptor cells release 5-HT in response to various taste stimuli. In the present study, we demonstrate that a subset of gustatory sensory neurons express functional

  8. 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 Central

    Weber, Tillmann; Vogt, Miriam A; Gartside, Sarah E; Berger, Stefan M; Lujan, Rafael; Lau, Thorsten; Herrmann, Elke; Sprengel, Rolf; Bartsch, Dusan; Gass, Peter

    2015-01-01

    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 Gria15-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 Gria15-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. PMID:25547714

  9. 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. PMID:15574737

  10. Receptor mechanisms for 5-hydroxytryptamine (5-HT) in isolated ovine umbilical vein.

    PubMed

    Zhang, L; Dyer, D C

    1990-08-10

    5-Hydroxytryptamine (5-HT) and 2,5-dimethoxy-4-methyl-amphetamine (DOM) produced a concentration-dependent contraction in isolated umbilical veins obtained from fetal lambs within 2 weeks of term. Contractions to 5-HT were antagonized by ketanserin, mianserin and methiothepin with the dissociation constants (KB) being 2.17 +/- 0.36, 1.37 +/- 0.55 and 1.98 +/- 0.48 nM, respectively. The order of potency of serotonergic agonists in this tissue was: DOM greater than 5-HT greater than alpha-methyl-5-HT greater than 1(3-chlorophenyl) piperazine (mCPP) greater than m-trifluoromethyl-phenylpiperazine (TFMPP) greater than 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) = 2-methyl-5-HT. alpha-Methyl-5-HT was a full agonist compared to 5-HT. DOM possessed greater affinity but less efficacy than that of 5-HT. The affinities and efficacies of the other agonists studied were lower than those of 5-HT. Variation in the sensitivity and potency of agonists is primarily due to variations in their affinity for 5-HT receptors. Assessment of receptor occupancy vs. functional response demonstrated very little, if any, receptor reserve for 5-HT receptors in this tissue. Contractile responses to DOM, 8-OH-DPAT, mCPP and 2-methyl-5-HT were effectively blocked by ketanserin. The dissociation constants (KB) of ketanserin against these agonists were as follows: DOM, 2.78 +/- 0.85 nM; 8-OH-DPAT, 3.47 +/- 1.12 nM; mCPP, 1.45 +/- 0.51 nM; 2-methyl-5-HT, 1.99 +/- 0.74 nM. The dissociation constant of MDL 72222 (3-tropanyl-3,5-dichlorobenzoate) vs. 5-HT was 13833 nM. No antagonism by prazosin (10(-7) M) or yohimbine (10(-7) M) of the responses to 5-HT was observed. These results indicate that 5-HT2 receptors are present in the ovine umbilical vein. 5-HT3 receptors were not present in this tissue. Activation of alpha-adrenoceptors was not involved in the contractions to 5-HT.

  11. LP-211 is a brain penetrant selective agonist for the serotonin 5-HT(7) receptor.

    PubMed

    Hedlund, Peter B; Leopoldo, Marcello; Caccia, Silvio; Sarkisyan, Gor; Fracasso, Claudia; Martelli, Giuliana; Lacivita, Enza; Berardi, Francesco; Perrone, Roberto

    2010-08-30

    We have determined the pharmacological profile of the new serotonin 5-HT(7) receptor agonist N-(4-cyanophenylmethyl)-4-(2-diphenyl)-1-piperazinehexanamide (LP-211). Radioligand binding assays were performed on a panel of 5-HT receptor subtypes. The compound was also evaluated in vivo by examining its effect on body temperature regulation in mice lacking the 5-HT(7) receptor (5-HT(7)(-/-)) and their 5-HT(7)(+/+) sibling controls. Disposition studies were performed in mice of both genotypes. It was found that LP-211 was brain penetrant and underwent metabolic degradation to 1-(2-diphenyl)piperazine (RA-7). In vitro binding assays revealed that RA-7 possessed higher 5-HT(7) receptor affinity than LP-211 and a better selectivity profile over a panel of 5-HT receptor subtypes. In vivo it was demonstrated that LP-211, and to a lesser degree RA-7, induced hypothermia in 5-HT(7)(+/+) but not in 5-HT(7)(-/-) mice. Our results suggest that LP-211 can be used as a 5-HT(7) receptor agonist in vivo. PMID:20600619

  12. Anxiolytic-like effects of 5-HT2 ligands on three mouse models of anxiety.

    PubMed

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

    2003-03-18

    The behavioural effects of 5-HT(2) receptor agonists, 5-HT(2A) and 5-HT(2C) receptor antagonists were investigated in the mouse four plates test (FPT), light/dark paradigm (L/D) and the elevated plus maze (EPM), in order to elucidate the role of the 5-HT(2) receptor subtypes in these models and to address the inconclusive results previously reported using rat psychopharmacological models. All compounds were administered intraperitoneally 30 min before each test. DOI, a preferential 5-HT(2A) agonist (0.5-8 mg/kg) and BW 723C86, a 5-HT(2B) agonist (8 and 16 mg/kg) provoked an anxiolytic-like response in the FPT. In the EPM, an anxiolytic-like effect was observed for DOI (0.5, 1 and 2 mg/kg), BW 723C86 (0.5, 4, 8 and 16 mg/kg), RO 60-0175 a 5-HT(2C) agonist (4 mg/kg) and the non-selective 5-HT(2) receptor agonist mCPP (0.25 mg/kg.). Ketanserin, a 5-HT(2A/2C) non-selective receptor antagonist (0.015 and 0.03 mg/kg), induced an anxiogenic-like effect in the L/D paradigm. The 5-HT(2C) antagonists (RS 10-2221, SDZ SER082 and SB 206553) were without effect in all three tests. These behavioural results are indicative of an anxiolytic-like action of 5-HT(2) receptor agonists, an anxiogenic-like effect of 5-HT(2A) receptor antagonism, whereas the blockade of 5-HT(2C) receptors are without effect in the mouse models studied.

  13. 5-HT potentiation of the GABAA response in the rat sacral dorsal commissural neurones

    PubMed Central

    Xu, Tian-Le; Pang, Zhi-Ping; Li, Ji-Shuo; Akaike, Norio

    1998-01-01

    The modulatory effect of 5-hydroxytryptamine (5-HT) on the γ-aminobutyric acidA (GABAA) response was investigated in the neurones freshly dissociated from the rat sacral dorsal commissural nucleus (SDCN) using the nystatin perforated patch recording configuration under the voltage-clamp conditions.5-HT potentiated GABA-induced Cl− current (IGABA) without affecting the reversal potential of IGABA and the apparent affinity of GABA to its receptor.α-Methyl-5-HT mimicked the potentiation effect of 5-HT on IGABA while ketanserine blocked it. 1-Oleoyl-2-acetyl-glycerol (OAG) potentiated IGABA, and the effect of 5-HT on IGABA was occluded by OAG pretreatment. In the presence of chelerythrine, 5-HT failed to potentiate IGABA, suggesting that protein kinase C (PKC) is involved in the pathway through which the activation of the 5-HT2 receptor potentiates the IGABA.The facilitatory effect of 5-HT on IGABA remained in the presence of BAPTA-AM. LiCl also had no effect on 5-HT-induced potentiation of IGABA.H-89, genistein, okadaic acid and pervanadate all had no effects on 5-HT potentiation of IGABA. Pertussis toxin treatment for 6–8 h did not block the facilitatory effect of 5-HT on IGABA.The present results show that GABAA receptor in the rat SDCN could be modulated in situ by 5-HT, one of the major transmitters involved in the supraspinal control of nociception, and that the phosphorylation of GABAA receptor by PKC may be sufficient to support such modulation. The results also strongly support the hypothesis that the cotransmission by 5-HT and GABA has an important role in the spinal cord. PMID:9690871

  14. A Novel Aminotetralin-Type Serotonin (5-HT) 2C Receptor-Specific Agonist and 5-HT2A Competitive Antagonist/5-HT2B Inverse Agonist with Preclinical Efficacy for Psychoses

    PubMed Central

    Morgan, Drake; Felsing, Daniel; Kondabolu, Krishnakanth; Rowland, Neil E.; Robertson, Kimberly L.; Sakhuja, Rajeev; Booth, Raymond G.

    2014-01-01

    Development of 5-HT2C agonists for treatment of neuropsychiatric disorders, including psychoses, substance abuse, and obesity, has been fraught with difficulties, because the vast majority of reported 5-HT2C selective agonists also activate 5-HT2A and/or 5-HT2B receptors, potentially causing hallucinations and/or cardiac valvulopathy. Herein is described a novel, potent, and efficacious human 5-HT2C receptor agonist, (−)-trans-(2S,4R)-4-(3′[meta]-bromophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (−)-MBP), that is a competitive antagonist and inverse agonist at human 5-HT2A and 5-HT2B receptors, respectively. (−)-MBP has efficacy comparable to the prototypical second-generation antipsychotic drug clozapine in three C57Bl/6 mouse models of drug-induced psychoses: the head-twitch response elicited by [2,5]-dimethoxy-4-iodoamphetamine; hyperlocomotion induced by MK-801 [(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (dizocilpine maleate)]; and hyperlocomotion induced by amphetamine. (−)-MBP, however, does not alter locomotion when administered alone, distinguishing it from clozapine, which suppresses locomotion. Finally, consumption of highly palatable food by mice was not increased by (−)-MBP at a dose that produced at least 50% maximal efficacy in the psychoses models. Compared with (−)-MBP, the enantiomer (+)-MBP was much less active across in vitro affinity and functional assays using mouse and human receptors and also translated in vivo with comparably lower potency and efficacy. Results indicate a 5-HT2C receptor-specific agonist, such as (−)-MBP, may be pharmacotherapeutic for psychoses, without liability for obesity, hallucinations, heart disease, sedation, or motoric disorders. PMID:24563531

  15. Yokukansan Increases 5-HT1A Receptors in the Prefrontal Cortex and Enhances 5-HT1A Receptor Agonist-Induced Behavioral Responses in Socially Isolated Mice

    PubMed Central

    Ueki, Toshiyuki; Mizoguchi, Kazushige; Yamaguchi, Takuji; Nishi, Akinori; Ikarashi, Yasushi; Hattori, Tomohisa; Kase, Yoshio

    2015-01-01

    The traditional Japanese medicine yokukansan has an anxiolytic effect, which occurs after repeated administration. In this study, to investigate the underlying mechanisms, we examined the effects of repeated yokukansan administration on serotonin 1A (5-HT1A) receptor density and affinity and its expression at both mRNA and protein levels in the prefrontal cortex (PFC) of socially isolated mice. Moreover, we examined the effects of yokukansan on a 5-HT1A receptor-mediated behavioral response. Male mice were subjected to social isolation stress for 6 weeks and simultaneously treated with yokukansan. Thereafter, the density and affinity of 5-HT1A receptors were analyzed by a receptor-binding assay. Levels of 5-HT1A receptor protein and mRNA were also measured. Furthermore, (±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT; a 5-HT1A receptor agonist) was injected intraperitoneally, and rearing behavior was examined. Social isolation stress alone did not affect 5-HT1A receptor density or affinity. However, yokukansan significantly increased receptor density and decreased affinity concomitant with unchanged protein and mRNA levels. Yokukansan also enhanced the 8-OH-DPAT-induced decrease in rearing behavior. These results suggest that yokukansan increases 5-HT1A receptors in the PFC of socially isolated mice and enhances their function, which might underlie its anxiolytic effects. PMID:26681968

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

    PubMed

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

    1995-10-01

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

  17. 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

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

    PubMed

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

    2007-06-01

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

  19. Role of 5-HT(1A) and 5-HT(1B) receptors in the antidepressant-like effect of piperine in the forced swim test.

    PubMed

    Mao, Qing-Qiu; Huang, Zhen; Ip, Siu-Po; Xian, Yan-Fang; Che, Chun-Tao

    2011-10-24

    Our previous studies have showed that treating mice with piperine significantly decreased the immobility time of the animals in the forced swim test and tail suspension test, which was related to up-regulation of serotonin (5-HT) level in the brain. The purpose of this study is to explore the contribution of 5-HT receptors in the antidepressant-like effect of piperine. The results showed that pre-treating mice with methiothepin (a non-selective 5-HT receptor antagonist, 0.1mg/kg, intraperitoneally), 4-(2'-methoxy-phenyl)-1-[2'-(n-2″-pyridinyl)-p-iodobenzamino-]ethyl-piperazine (a selective 5-HT(1A) receptor antagonist, 1mg/kg, subcutaneously) or 1-(2-(1-pyrrolyl)-phenoxy)-3-isopropylamino-2-propanol (a 5-HT(1B) receptor antagonist, 2.5mg/kg, intraperitoneally) was found to abolish the anti-immobility effect of piperine (10mg/kg, intraperitoneally) in the forced swim test. On the other hand, a sub-effective dose of piperine (1mg/kg, intraperitoneally) produced a synergistic antidepressant-like effect with (+)-8-hydroxy-2-(di-n-propylamino)tetralin (a 5-HT(1A) receptor agonist, 1mg/kg, intraperitoneally) or anpirtoline (a 5-HT(1B) receptor agonist, 0.25mg/kg, intraperitoneally). Taken together, these results suggest that the antidepressant-like effect of piperine in the mouse forced swim test may be mediated, at least in part, by the activation of 5-HT(1A) and 5-HT(1B) receptors.

  20. Phosphotidylinositol turnover in vascular, uterine, fundal, and tracheal smooth muscle: effect of serotonin (5HT)

    SciTech Connect

    Cohen, M.L.; Wittenauer, L.A.

    1986-03-01

    In brain, platelets, and aorta, 5HT has been reported to increase phosphotidylinositol turnover, an effect linked to 5HT/sub 2/ receptors. The authors examined the effect of 5HT on /sup 3/H-inositol-1-phosphate (/sup 3/H-I-P) in tissues possessing 5HT/sub 2/ receptors that mediate contraction to 5HT (rat jugular vein, aorta, uterus and guinea pig trachea) and in a tissue in which contraction to 5HT is not mediated by 5HT/sub 2/ receptors (rat stomach fundus). Tissues were incubated (37/sup 0/C, 95% O/sub 2/, 5% CO/sub 2/) with /sup 3/H-inositol (90 min), washed, LiCl/sub 2/ (10 mM) and 5HT added for 90 min, extracted, and /sup 3/H-I-P eluted from a Dowex-1 column. Basal /sup 3/H-I-P was 10-fold higher in the uterus than in the other tissues. 5HT (10/sup -6/-10/sup -4/M) increased /sup 3/H-I-P in the jugular vein, aorta, and uterus but not in the trachea or fundus. Maximum increase was greatest in the jugular vein (8-fold) with an ED/sub 50/ of 0.4 ..mu..M 5HT. The selective 5HT/sub 2/ receptor blocker, LY53857 (10/sup -8/M) antagonized the increase in /sup 3/H-I-P by 5HT in the jugular vein, aorta and uterus. Pargyline (10/sup -5/M) added to the trachea and fundus did not unmask an effect of 5HT (10/sup -4/M). These data suggest that (1) the jugular vein produced the most sensitive response to 5HT-induced increases in /sup 3/H-I-P, (2) increases in /sup 3/H-I-P by 5HT in smooth muscle may be linked to 5HT/sub 2/ receptors and (3) activation of 5HT/sub 2/ receptors as occurred in the trachea will not always increase /sup 3/H-I-P.

  1. Divergent effects of the ‘biased’ 5-HT1A receptor agonists F15599 and F13714 in a novel object pattern separation task

    PubMed Central

    van Goethem, N P; Schreiber, R; Newman-Tancredi, A; Varney, M; Prickaerts, J

    2015-01-01

    Background and Purpose Pattern separation, that is, the formation of distinct representations from similar inputs, is an important hippocampal process implicated in cognitive domains like episodic memory. A deficit in pattern separation could lead to memory impairments in several psychiatric and neurological disorders. Hence, mechanisms by which pattern separation can be increased are of potential therapeutic interest. Experimental approach 5-HT1A receptors are involved in spatial memory. Herein we tested the ‘biased’ 5-HT1A receptor agonists F15599, which preferentially activates post-synaptic heteroreceptors, and F13714, which preferentially activates raphe-located autoreceptors, in rats in a novel spatial task assessing pattern separation, the object pattern separation (OPS) task. Key Results The acetylcholinesterase inhibitor donepezil, which served as a positive control, significantly improved spatial pattern separation at a dose of 1 mg·kg−1, p.o. F15599 increased pattern separation at 0.04 mg·kg−1, i.p., while F13714 decreased pattern separation at 0.0025 mg·kg−1, i.p. The selective 5-HT1A receptor antagonist WAY-100635 (0.63 mg·kg−1, s.c.) counteracted the effects of both agonists. These data suggest that acute preferential activation of post-synaptic 5-HT1A heteroreceptors improves spatial pattern separation, whereas acute preferential activation of raphe-located 5-HT1A autoreceptors impairs performance. Conclusions and Implications We successfully established and validated a novel, simple and robust OPS task and observed a diverging profile of response with ‘biased’ 5-HT1A receptor agonists based on their targeting of receptors in distinct brain regions. Our data suggest that the post-synaptic 5-HT1A receptor consists of a potential novel molecular target to improve pattern separation performance. PMID:25572672

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

    PubMed Central

    Allen, John A.; Yadav, Prem N.

    2008-01-01

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

  3. Rats with constitutionally upregulated/downregulated platelet 5HT transporter: differences in anxiety-related behavior.

    PubMed

    Hranilovic, Dubravka; Cicin-Sain, Lipa; Bordukalo-Niksic, Tatjana; Jernej, Branimir

    2005-12-01

    Serotonin (5-hydroxytryptamine, 5HT) plays important roles in both embryonic development as a mediator of neurogenesis and in the mature brain as a neurotransmitter. Disturbances in serotonergic transmission have been indicated in several psychiatric disorders. In the search for the biological substrates of psychiatric diseases, studies using animal models represent complementary approaches to studies on human subjects. Wistar-Zagreb 5HT rats, with constitutionally upregulated/downregulated platelet 5HT transporter (termed high- and low-5HT rats, respectively), have been developed in our laboratory as a model for studying various aspects of 5HT function. In this work, we have searched for potential behavioral differences between Wistar-Zagreb 5HT rat sublines in three anxiety paradigms: hole-board, zero-maze, and social interaction test. In all three tests, significant differences in behavior between Wistar-Zagreb 5HT sublines have been observed, indicating higher levels of anxiety-related behavior in high-5HT rats. In the social interaction test, high-5HT animals spent less time in active contact with conspecifics and displayed a narrower spectrum of social behaviors than their low-5HT counterparts, while in the zero-maze and hole-board tasks, they showed a lower level of exploratory activity (head dips and nose pokes) in comparison to low-5HT rats. On the other hand, thigmotactic behavior (the percentage of time spent in open quadrants of zero-maze and the percentage of central holes visited in hole-board) did not differ between the sublines. The results suggest that as a result of selection process, a specific component of anxiety-related behavior (i.e. exploratory activity directed towards a novel environment and conspecifics) has been affected in Wistar-Zagreb 5HT rats. PMID:16139900

  4. Rats with constitutionally upregulated/downregulated platelet 5HT transporter: differences in anxiety-related behavior.

    PubMed

    Hranilovic, Dubravka; Cicin-Sain, Lipa; Bordukalo-Niksic, Tatjana; Jernej, Branimir

    2005-12-01

    Serotonin (5-hydroxytryptamine, 5HT) plays important roles in both embryonic development as a mediator of neurogenesis and in the mature brain as a neurotransmitter. Disturbances in serotonergic transmission have been indicated in several psychiatric disorders. In the search for the biological substrates of psychiatric diseases, studies using animal models represent complementary approaches to studies on human subjects. Wistar-Zagreb 5HT rats, with constitutionally upregulated/downregulated platelet 5HT transporter (termed high- and low-5HT rats, respectively), have been developed in our laboratory as a model for studying various aspects of 5HT function. In this work, we have searched for potential behavioral differences between Wistar-Zagreb 5HT rat sublines in three anxiety paradigms: hole-board, zero-maze, and social interaction test. In all three tests, significant differences in behavior between Wistar-Zagreb 5HT sublines have been observed, indicating higher levels of anxiety-related behavior in high-5HT rats. In the social interaction test, high-5HT animals spent less time in active contact with conspecifics and displayed a narrower spectrum of social behaviors than their low-5HT counterparts, while in the zero-maze and hole-board tasks, they showed a lower level of exploratory activity (head dips and nose pokes) in comparison to low-5HT rats. On the other hand, thigmotactic behavior (the percentage of time spent in open quadrants of zero-maze and the percentage of central holes visited in hole-board) did not differ between the sublines. The results suggest that as a result of selection process, a specific component of anxiety-related behavior (i.e. exploratory activity directed towards a novel environment and conspecifics) has been affected in Wistar-Zagreb 5HT rats.

  5. Signalling properties and pharmacology of a 5-HT7 -type serotonin receptor from Tribolium castaneum.

    PubMed

    Vleugels, R; Lenaerts, C; Vanden Broeck, J; Verlinden, H

    2014-04-01

    In the last decade, genome sequence data and gene structure information on invertebrate receptors has been greatly expanded by large sequencing projects and cloning studies. This information is of great value for the identification of receptors; however, functional and pharmacological data are necessary for an accurate receptor classification and for practical applications. In insects, an important group of neurotransmitter and neurohormone receptors, for which ample sequence information is available but pharmacological information is missing, are the biogenic amine G protein-coupled receptors (GPCRs). In the present study, we investigated the sequence information, pharmacology and signalling properties of a 5-HT7 -type serotonin receptor from the red flour beetle, Tribolium castaneum (Trica5-HT7 ). The receptor encoding cDNA shows considerable sequence similarity with cognate 5-HT7 receptors and phylogenetic analysis also clusters the receptor within this 5-HT receptor group. Real-time reverse transcription PCR demonstrated high expression levels in the brain, indicating the possible importance of this receptor in neural processes. Trica5-HT7 was dose-dependently activated by 5-HT, which induced elevated intracellular cyclic AMP levels but had no effect on calcium signalling. The synthetic agonists, α-methyl 5-HT, 5-methoxytryptamine, 5-carboxamidotryptamine and 8-hydroxy-2-(dipropylamino)tetralin hydrobromide, showed a response, although with a much lower potency and efficacy than 5-HT. Ketanserin and methiothepin were the most potent antagonists. Both showed characteristics of competitive inhibition on Trica5-HT7 . The signalling pathway and pharmacological profile offer important information that will facilitate functional and comparative studies of 5-HT receptors in insects and other invertebrates. The pharmacology of invertebrate 5-HT receptors differs considerably from that of vertebrates. The present study may therefore contribute to establishing a more

  6. Sulfonyl-containing modulators of serotonin 5-HT6 receptors and their pharmacophore models

    NASA Astrophysics Data System (ADS)

    Ivachtchenko, A. V.

    2014-05-01

    Data published in recent years on the synthesis of serotonin 5-HT6 receptor modulators are summarized. Modulators with high affinity for 5-HT6 receptors exhibiting different degrees of selectivity — from highly selective to semiselective and multimodal — are described. Clinical trial results are reported for the most promising serotonin 5-HT6 receptor modulators attracting special attention of medicinal chemists. The bibliography includes 128 references.

  7. Volunteer models for predicting antiemetic activity of 5-HT3-receptor antagonists.

    PubMed Central

    Minton, N A

    1994-01-01

    1. Selective 5-HT3-receptor antagonists are highly effective in preventing nausea and vomiting associated with chemotherapy, radiotherapy and surgery. Their pharmacological activity may be determined in vitro and in animal models of emesis. However, these methods may not give an accurate indication of the antiemetic dose range of 5-HT3-receptor antagonists in patients. Two volunteer models have been used to predict more accurately clinically effective antiemetic doses of 5-HT3-receptor antagonists. 2. The flare response to intradermal 5-HT is thought to be mediated by excitation of 5-HT3-receptors on cutaneous afferents, with release of substance P and subsequent vasodilation. Antagonism of the flare response appears to provide an indication of the effective antiemetic dose of 5-HT3-receptor antagonists but data on duration of action are conflicting. 3. Ipecacuanha-induced emesis is thought to be mediated through both peripheral and central 5-HT3-receptors. Antagonism of this response has demonstrated a close correlation with clinically effective antiemetic doses of the specific 5-HT3-receptor antagonist, ondansetron, and has the advantage of being more conceptually relevant than the flare model. 4. Further work, with newer 5-HT3-receptor antagonists, will clarify the role of these models as predictive of the use of these drugs in clinical practice. PMID:7917768

  8. 5-HT radioligands for human brain imaging with PET and SPECT.

    PubMed

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

    2013-01-01

    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-HT(1A), 5-HT(1B), 5-HT(2A), and 5-HT(4) 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.

  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

    2014-08-01

    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. The 5-HT3 receptor is essential for exercise-induced hippocampal neurogenesis and antidepressant effects.

    PubMed

    Kondo, M; Nakamura, Y; Ishida, Y; Shimada, S

    2015-11-01

    Exercise has a variety of beneficial effects on brain structure and function, such as hippocampal neurogenesis, mood and memory. Previous studies have shown that exercise enhances hippocampal neurogenesis, induces antidepressant effects and improves learning behavior. Brain serotonin (5-hydroxytryptamine, 5-HT) levels increase following exercise, and the 5-HT system has been suggested to have an important role in these exercise-induced neuronal effects. However, the precise mechanism remains unclear. In this study, analysis of the 5-HT type 3A receptor subunit-deficient (htr3a(-/-)) mice revealed that lack of the 5-HT type 3 (5-HT3) receptor resulted in loss of exercise-induced hippocampal neurogenesis and antidepressant effects, but not of learning enhancement. Furthermore, stimulation of the 5-HT3 receptor promoted neurogenesis. These findings demonstrate that the 5-HT3 receptor is the critical target of 5-HT action in the brain following exercise, and is indispensable for hippocampal neurogenesis and antidepressant effects induced by exercise. This is the first report of a pivotal 5-HT receptor subtype that has a fundamental role in exercise-induced morphological changes and psychological effects.

  11. Discovery of 2-substituted benzoxazole carboxamides as 5-HT3 receptor antagonists.

    PubMed

    Yang, Zhicai; Fairfax, David J; Maeng, Jun-Ho; Masih, Liaqat; Usyatinsky, Alexander; Hassler, Carla; Isaacson, Soshanna; Fitzpatrick, Kevin; DeOrazio, Russell J; Chen, Jianqing; Harding, James P; Isherwood, Matthew; Dobritsa, Svetlana; Christensen, Kevin L; Wierschke, Jonathan D; Bliss, Brian I; Peterson, Lisa H; Beer, Cathy M; Cioffi, Christopher; Lynch, Michael; Rennells, W Martin; Richards, Justin J; Rust, Timothy; Khmelnitsky, Yuri L; Cohen, Marlene L; Manning, David D

    2010-11-15

    A new class of 2-substituted benzoxazole carboxamides are presented as potent functional 5-HT(3) receptor antagonists. The chemical series possesses nanomolar in vitro activity against human 5-HT(3)A receptors. A chemistry optimization program was conducted and identified 2-aminobenzoxazoles as orally active 5-HT(3) receptor antagonists with good metabolic stability. These novel analogues possess drug-like characteristics and have potential utility for the treatment of diseases attributable to improper 5-HT(3) receptor function, especially diarrhea predominant irritable bowel syndrome (IBS-D).

  12. 5-HT-moduline, a 5-HT(1B/1D) receptor endogenous modulator, interacts with dopamine release measured in vivo by microdialysis.

    PubMed

    Bentué-Ferrer, D; Reymann, J M; Rousselle, J C; Massot, O; Bourin, M; Allain, H; Fillion, G

    1998-10-01

    5-Hydroxytryptamine-moduline (5-HT-moduline) is an endogenous tetrapeptide (Leu-Ser-Ala-Leu) recently isolated and characterized from mammalian brain. This compound interacts with 5-HT1B receptors as a non-competitive, high-affinity antagonist and has the properties of an allosteric modulator. 5-HT-moduline could play an important role in the regulation of serotonergic transmission and also, through heteroreceptors, dopaminergic transmission. The aim of this work was to examine the potential ability of 5-HT-moduline to modify the basal extracellular concentration of dopamine and its metabolites (3-methoxytyramine, dihydroxyphenylacetic acid and homovanillic acid), in the rat striatum and to determine its potential interaction with the stimulating activity of a specific 5-HT1B receptor agonist, 3-(1,2,5,6-tetrahydropyrid-4-yl) pyrrolo [3,2-b] pyrid-5-one (CP-93,129), on the release of dopamine. The technique is based on in vivo microdialysis using probes implanted in the striatum of the conscious rat. Results showed that the perfusion of 5-HT-moduline directly into this structure (1.25 mM) increased the striatal level of dopamine by two-fold (104% of the absolute basal release values, P = 0.0015) and that of 3-methoxytyramine by 3-fold (293%, P = 0.0001) without any change in the terminal metabolite concentrations. The intrastriatal administration of CP-93,129 induced a statistically significant, dose-dependent increase of dopamine levels (P < 0.0001). Coperfusion of 5-HT-moduline did not significantly alter the effect of CP-93,129 at 0.1 and 0.5 mM, but appeared to have an additive effect on the lowest dose (P = 0.0406). The results obtained show that 5-HT-moduline directly administered into the striatum increases the release of dopamine in this area. Presumably, this effect results from the desensitization of 5-HT1B receptors located on dopamine terminals. However, the fact that a 5-HT1B receptor agonist (CP-93,129) also increased the release of dopamine in the

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

    PubMed

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

    2014-06-01

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

  14. Astrocytic transactivation by alpha2A-adrenergic and 5-HT2B serotonergic signaling.

    PubMed

    Peng, Liang; Li, Baoman; Du, Ting; Kong, Ebenezer K C; Hu, Xiaoling; Zhang, Shiquen; Shan, Xiaolei; Zhang, Meixia

    2010-11-01

    EGF receptor transactivation has been known for more than ten years. It is a signal pathway in which a G-protein-coupled receptor (GPCR) signal leads to release of a growth factor, which in turn activates the EGF receptor-tyrosine kinase in the same or adjacent cells. Astrocytes express a number of GPCRs and play key roles in brain function. Astrocytic transactivation is of special interest, since its autocrine effect may regulate gene expression and alter cell functions in the cells themselves and its paracrine effect may provide additional opportunities for cross-talk between astrocytes and their neighbors, such as neurons. The signal pathways of EGF transactivation are complicated. This does not only apply to the pathways leading to shedding of growth factor(s), but also to the downstream signal pathways of the EGF receptor, i.e., MAPK and PI3K. The latter may vary according to the type of growth factor released, the sites of tyrosine phosphorylation on the EGF receptor, and the duration of the phosphorylation. Using primary cell cultures we have found that dexmedetomidine, a specific alpha(2)-adrenergic receptor, induced shedding of HB-EGF from astrocytes, which in turn transactivated EGF receptors and stimulated astrocytic c-Fos and FosB expression. At the same time released HB-EGF protected neurons from injury caused by H(2)O(2). We have also confirmed dexmedetomidine transactivation in the brain in vivo. EGF transactivation by 5-HT(2B) receptor stimulation was responsible for up-regulation of cPLA(2) in astrocytes by fluoxetine, an antidepressant and inhibitor of the serotonin transporter, which also is a specific 5-HT(2B) agonist. PMID:20450946

  15. An Orally Active Phenylaminotetralin-Chemotype Serotonin 5-HT7 and 5-HT1A Receptor Partial Agonist that Corrects Motor Stereotypy in Mouse Models.

    PubMed

    Canal, Clinton E; Felsing, Daniel E; Liu, Yue; Zhu, Wanying; Wood, JodiAnne T; Perry, Charles K; Vemula, Rajender; Booth, Raymond G

    2015-07-15

    Stereotypy (e.g., repetitive hand waving) is a key phenotype of autism spectrum disorder, Fragile X and Rett syndromes, and other neuropsychiatric disorders, and its severity correlates with cognitive and attention deficits. There are no effective treatments, however, for stereotypy. Perturbation of serotonin (5-HT) neurotransmission contributes to stereotypy, suggesting that distinct 5-HT receptors may be pharmacotherapeutic targets to treat stereotypy and related neuropsychiatric symptoms. For example, preclinical studies indicate that 5-HT7 receptor activation corrects deficits in mouse models of Fragile X and Rett syndromes, and clinical trials for autism are underway with buspirone, a 5-HT1A partial agonist with relevant affinity at 5-HT7 receptors. Herein, we report the synthesis, in vitro molecular pharmacology, behavioral pharmacology, and pharmacokinetic parameters in mice after subcutaneous and oral administration of (+)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine ((+)-5-FPT), a new, dual partial agonist targeting both 5-HT7 (Ki = 5.8 nM, EC50 = 34 nM) and 5-HT1A (Ki = 22 nM, EC50 = 40 nM) receptors. Three unique, heterogeneous mouse models were used to assess the efficacy of (+)-5-FPT to reduce stereotypy: idiopathic jumping in C58/J mice, repetitive body rotations in C57BL/6J mice treated with the NMDA antagonist, MK-801, and repetitive head twitching in C57BL/6J mice treated with the 5-HT2 agonist, DOI. Systemic (+)-5-FPT potently and efficaciously reduced or eliminated stereotypy in each of the mouse models without altering locomotor behavior on its own, and additional tests showed that (+)-5-FPT, at the highest behaviorally active dose tested, enhanced social interaction and did not cause behaviors indicative of serotonin syndrome. These data suggest that (+)-5-FPT is a promising medication for treating stereotypy in psychiatric disorders.

  16. Analysis of free ACh and 5-HT in milk from four different species and their bioactivity on 5-HT(3) and nACh receptors.

    PubMed

    Gallegos-Perez, Jose-Luis; Limon, Agenor; Reyes-Ruiz, Jorge M; Alshanqeeti, Ali S; Aljohi, Mohammad A; Miledi, Ricardo

    2014-07-25

    Milk is one of the most beneficial aliments and is highly recommended in normal conditions; however, in certain disorders, like irritable bowel syndrome, cow milk and dairy products worsen the gastric symptoms and their use is not recommended. Among the most recognized milk-induced gatrointestinal symptoms are abdominal pain, nausea and vomiting, which are processes controlled by cholinergic and serotonergic transmission. Whether the presence of bioavailable ACh and 5-HT in milk may contribute to normal peristalsis, or to the developing of these symptoms, is not known. In this work we attempt to determine whether the content of free ACh and 5-HT is of physiological significance in milk from four different species: cow (bovine), goat, camel and human. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to identify and quantify free ACh and 5-HT in milk, and activation of the serotonergic and cholinergic ionotropic receptors was investigated using electrophysiological experiments. Our principal hypothesis was that milk from these four species had sufficient free ACh and 5-HT to activate their correspondent receptors expressed in a heterologous system. Our results showed a more complex picture, in which free ACh and 5-HT and their ability to activate cholinergic and serotonergic receptors are not correlated. This work is a first step to elucidate whether 5-HT and ACh, at the concentrations present in the milk, can be associated to a direct function in the GI.

  17. Human serotonin 1D receptor is encoded by a subfamily of two distinct genes: 5-HT1D alpha and 5-HT1D beta.

    PubMed Central

    Weinshank, R L; Zgombick, J M; Macchi, M J; Branchek, T A; Hartig, P R

    1992-01-01

    The serotonin 1D (5-HT1D) receptor is a pharmacologically defined binding site and functional receptor site. Observed variations in the properties of 5-HT1D receptors in different tissues have led to the speculation that multiple receptor proteins with slightly different properties may exist. We report here the cloning, deduced amino acid sequences, pharmacological properties, and second-messenger coupling of a pair of human 5-HT1D receptor genes, which we have designated 5-HT1D alpha and 5-HT1D beta due to their strong similarities in sequence, pharmacological properties, and second-messenger coupling. Both genes are free of introns in their coding regions, are expressed in the human cerebral cortex, and can couple to inhibition of adenylate cyclase activity. The pharmacological binding properties of these two human receptors are very similar, and match closely the pharmacological properties of human, bovine, and guinea pig 5-HT1D sites. Both receptors exhibit high-affinity binding of sumatriptan, a new anti-migraine medication, and thus are candidates for the pharmacological site of action of this drug. Images PMID:1565658

  18. Stress-induced alterations in 5-HT1A receptor transcriptional modulators NUDR and Freud-1.

    PubMed

    Szewczyk, Bernadeta; Kotarska, Katarzyna; Daigle, Mireille; Misztak, Paulina; Sowa-Kucma, Magdalena; Rafalo, Anna; Curzytek, Katarzyna; Kubera, Marta; Basta-Kaim, Agnieszka; Nowak, Gabriel; Albert, Paul R

    2014-11-01

    The effect of stress on the mRNA and protein level of the 5-HT1A receptor and two of its key transcriptional modulators, NUDR and Freud-1, was examined in the prefrontal cortex (PFC) and hippocampus (Hp) using rodent models: olfactory bulbectomy (OB) and prenatal stress (PS) in male and female rats; chronic mild stress in male rats (CMS) and pregnancy stress. In PFC, CMS induced the most widespread changes, with significant reduction in both mRNA and protein levels of NUDR, 5-HT1A receptor and in Freud-1 mRNA; while in Hp 5-HT1A receptor and Freud-1 protein levels were also decreased. In male, but not female OB rats PFC Freud-1 and 5-HT1A receptor protein levels were reduced, while in Hp 5-HT1A receptor, Freud-1 and NUDR mRNA's but not protein were reduced. In PS rats PFC 5-HT1A receptor protein was reduced more in females than males; while in Hp Freud-1 protein was increased in females. In pregnancy stress, PFC NUDR, Freud-1 and 5-HT1A protein receptor levels were reduced, and in HP 5-HT1A receptor protein levels were also reduced; in HP only NUDR and Freud-1 mRNA levels were reduced. Overall, CMS and stress during pregnancy produced the most salient changes in 5-HT1A receptor and transcription factor expression, suggesting a primary role for altered transcription factor expression in chronic regulation of 5-HT1A receptor expression. By contrast, OB (in males) and PS (in females) produced gender-specific reductions in PFC 5-HT1A receptor protein levels, suggesting a role for post-transcriptional regulation. These and previous data suggest that chronic stress might be a key regulator of NUDR/Freud-1 gene expression.

  19. Role of central vagal 5-HT3 receptors in gastrointestinal physiology and pathophysiology

    PubMed Central

    Browning, Kirsteen N.

    2015-01-01

    Vagal neurocircuits are vitally important in the co-ordination and modulation of GI reflexes and homeostatic functions. 5-hydroxytryptamine (5-HT; serotonin) is critically important in the regulation of several of these autonomic gastrointestinal (GI) functions including motility, secretion and visceral sensitivity. While several 5-HT receptors are involved in these physiological responses, the ligand-gated 5-HT3 receptor appears intimately involved in gut-brain signaling, particularly via the afferent (sensory) vagus nerve. 5-HT is released from enterochromaffin cells in response to mechanical or chemical stimulation of the GI tract which leads to activation of 5-HT3 receptors on the terminals of vagal afferents. 5-HT3 receptors are also present on the soma of vagal afferent neurons, including GI vagal afferent neurons, where they can be activated by circulating 5-HT. The central terminals of vagal afferents also exhibit 5-HT3 receptors that function to increase glutamatergic synaptic transmission to second order neurons of the nucleus tractus solitarius within the brainstem. While activation of central brainstem 5-HT3 receptors modulates visceral functions, it is still unclear whether central vagal neurons, i.e., nucleus of the tractus solitarius (NTS) and dorsal motor nucleus of the vagus (DMV) neurons themselves also display functional 5-HT3 receptors. Thus, activation of 5-HT3 receptors may modulate the excitability and activity of gastrointestinal vagal afferents at multiple sites and may be involved in several physiological and pathophysiological conditions, including distention- and chemical-evoked vagal reflexes, nausea, and vomiting, as well as visceral hypersensitivity. PMID:26578870

  20. Development of imidazole alkanoic acids as mGAT3 selective GABA uptake inhibitors.

    PubMed

    Hack, Silke; Wörlein, Babette; Höfner, Georg; Pabel, Jörg; Wanner, Klaus T

    2011-05-01

    A new series of potential GABA uptake inhibitors starting from of 1H-imidazol-4-ylacetic acid with the carboxylic acid side chain originating from different positions and varying in length have been synthesized and tested for the inhibitory potency at the four GABA uptake transporters mGAT1-4 stably expressed in HEK cells. Further two bicyclic compounds with a rigidified carboxylic acid side chain were included in this study. The results of the biological tests indicated that most ω-imidazole alkanoic and alkenoic acid derivatives exhibit the highest potencies as GABA uptake inhibitors at mGAT3.

  1. The involvement of intracellular Ca2+ in 5-HT1B/1D receptor-mediated contraction of the rabbit isolated renal artery

    PubMed Central

    Hill, P B; Dora, K A; Hughes, A D; Garland, C J

    2000-01-01

    5-Hydroxytryptamine1B/1D (5-HT1B/1D) receptor coupling to contraction was investigated in endothelium-denuded rabbit isolated renal arteries, by simultaneously measuring tension and intracellular [Ca2+], and tension in permeabilized smooth muscle cells.In intact arterial segments, 1 nM–10 μM 5-HT failed to induce contraction or increase the fura-2 fluorescence ratio (in the presence of 1 μM ketanserin and prazosin to block 5-HT2 and α1-adrenergic receptors, respectively). However, in vessels pre-exposed to either 20 mM K+ or 30 nM U46619, 5-HT stimulated concentration-dependent increases in both tension and intracellular [Ca2+].1 nM–10 μM U46619 induced concentration-dependent contractions. In the presence of nifedipine (0.3 and 1 μM) the maximal contraction to U46619 (10 μM) was reduced by around 70%. The residual contraction was abolished by the putative receptor operated channel inhibitor, SKF 96365 (2 μM).With 0.3 μM nifedipine present, 100 nM U46619 evoked similar contraction to 30 nM U46619 in the absence of nifedipine, but contraction to 5-HT (1 nM–10 μM) was abolished.In permeabilized arterial segments, 10 mM caffeine, 1 μM IP3 or 100 μM phenylephrine, each evoked transient contractions by releasing Ca2+ from intracellular stores, whereas 5-HT had no effect. In intact arterial segments pre-stimulated with 20 mM K+, 5-HT-evoked contractions were unaffected by 1 μM thapsigargin, which inhibits sarco- and endoplasmic reticulum calcium-ATPases.In vessels permeabilized with α-toxin and then pre-contracted with Ca2+ and GTP, 5-HT evoked further contraction, reflecting increased myofilament Ca2+-sensitivity.Contraction linked to 5-HT1B/1D receptor stimulation in the rabbit renal artery can be explained by an influx of external Ca2+ through voltage-dependent Ca2+ channels and sensitization of the contractile myofilaments to existing levels of Ca2+, with no release of Ca2+ from intracellular stores. PMID

  2. Involvement of 5-HT receptor subtypes in the discriminative stimulus properties of mescaline.

    PubMed

    Appel, J B; Callahan, P M

    1989-01-01

    In order to further evaluate the extent to which particular 5-HT receptor subtypes (5-HT1, 5-HT2) might be involved in the behavioral effects of hallucinogenic drugs, rats were trained to discriminate mescaline (10 mg/kg i.p.) from saline and were given substitution (generalization) and combination (antagonism) tests with putatively selective serotonergic and related neuroactive compounds. The mescaline cue generalized to relatively high doses of the 5-HT2 agonists, 2,5-dimethoxy-4-methylamphetamine (DOM), LSD and psilocybin; the extent of generalization to 5-HT1 agonists (8-hydroxy-2-[diethylamino]tetralin (8-OHDPAT), RU-24969 and 8-hydroxy-2-[di-n-propylamino]tetralin (TFMPP] was unclear. Combinations of the training drug and sufficiently high doses of 5-HT2 antagonists (ketanserin, LY-53857, pirenperone) were followed by saline-lever responding; less selective central 5-HT (metergoline), and DA (SCH-23390, haloperidol) antagonists, did not block the mescaline cue. These data suggest that 5-HT2 receptors are involved in the stimulus properties of mescaline.

  3. 5-HT7 receptor signaling: improved therapeutic strategy in gut disorders

    PubMed Central

    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. PMID:25565996

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

    PubMed Central

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

    2009-01-01

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

  5. Central effects of 5-HT on respiratory and hypoglossal activities in the adult cat.

    PubMed

    Rose, D; Khater-Boidin, J; Toussaint, P; Duron, B

    1995-07-01

    The activities of the diaphragmatic, internal intercostal and hypoglossal-innervated muscles were studied in adult decerebrate cats in response to 5-HT and related agents (8-OH-DPAT and DOI). The drugs were placed on the floor of the IVth ventricle. The mean respiratory frequency (Fi) increased (124-193% of the control value) within 3 min of the 5-HT application, and decreased thereafter (30-90%). The mean Ti and Te changed similarly, but opposite to Fi. With some delay, the hypoglossal-innervated muscles were tonically activated or exhibited increased activities. Methysergide pretreatment completely blocked the effect of 5-HT on all the respiratory parameters and the hypoglossal-innervated muscles activities. The responses to 8-OH-DPAT and DOI indicate that 5-HT modulates the respiratory frequency via activation of both 5-HT1A and 5-HT2 receptors. Nevertheless, the effect of 5-HT on both the expiratory and hypoglossal-innervated muscles seems to depend on 5-HT2 receptors activation only.

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

    PubMed Central

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

    2012-01-01

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

  7. Comparative assessment of (18) F-Mefway as a serotonin 5-HT1A receptor PET imaging agent across species: Rodents, nonhuman primates, and humans.

    PubMed

    Mukherjee, Jogeshwar; Bajwa, Alisha K; Wooten, Dustin W; Hillmer, Ansel T; Pan, Min-Liang; Pandey, Suresh K; Saigal, Neil; Christian, Bradley T

    2016-05-01

    We have developed (18) F-trans-Mefway ((18) F-Mefway) for positron emission tomography (PET) imaging studies of serotonin 5-HT1A receptors which are implicated in various brain functions. Translation of imaging the 5-HT1A receptor in animal models to humans will facilitate an understanding of the role of the receptor in human brain disorders. We report comparative brain distribution of (18) F-Mefway in normal mice, rats, monkeys, and healthy human volunteers. Mefway was found to be very selective, with subnanomolar affinity for the 5-HT1A receptor. Affinities of >55 nM were found for all other human-cloned receptor subtypes tested. Mefway was found to be a poor substrate (>30 μM) for the multidrug resistance 1 protein, suggesting low likelihood of brain uptake being affected by P-glycoprotein. Cerebellum was used as a reference region in all imaging studies across all species due to the low levels of (18) F-Mefway binding. Consistent binding of (18) F-Mefway in cortical regions, hippocampus, and raphe was observed across all species. (18) F-Mefway in the human brain regions correlated with the known postmortem distribution of 5-HT1A receptors. Quantitation of raphe was affected by the resolution of the PET scanners in rodents, whereas monkeys and humans showed a raphe to cerebellum ratio of approximately 3. (18) F-Mefway appears to be an effective 5-HT1A receptor imaging agent in all models, including humans. (18) F-Mefway therefore may be used to quantify 5-HT1A receptor distribution in brain regions for the study of various CNS disorders. J. Comp. Neurol. 524:1457-1471, 2016. © 2015 Wiley Periodicals, Inc.

  8. 5-HT(1A)-receptor over-expressing mice: genotype and sex dependent responses to antidepressants in the forced swim-test.

    PubMed

    Günther, Lydia; Rothe, Julia; Rex, André; Voigt, Jörg-Peter; Millan, Mark J; Fink, Heidrun; Bert, Bettina

    2011-09-01

    Deficiencies in serotonergic neurotransmission are involved in the pathophysiology of depression. Due to its modulatory effect on serotonin (5-HT) release, the 5-HT(1A)-receptor is thought to play a decisive role in the therapy of this mood disorder. However, it is not fully understood how antidepressant effects are mediated by pre- and postsynaptic receptor sites. In this study we examined the impact of postsynaptic 5-HT(1A)-receptor over-expression in corticolimbic areas of male and female mice on the performance in the forced swim-test (FST). Furthermore, we investigated their response to the serotonin selective reuptake inhibitor (SSRI) citalopram in comparison to the selective noradrenaline reuptake inhibitor reboxetine, as well as the partial 5-HT(1A)-receptor agonists, buspirone and S 15535. Additionally, these drugs were evaluated in the open field-test in order to observe effects on motor activity. The density of 5-HT(1A)-receptors in discrete corticolimbic regions was determined in detail by quantitative autoradiography with [(3)H]8-OH-DPAT to investigate genotype as well as sex dependent differences in the expression pattern. [(3)H]8-OH-DPAT binding differed depending on sex with female mice of both genotypes displaying higher receptor binding in distinct brain areas. In the FST untreated male but not female over-expressing (OE) mice showed an antidepressant-like behaviour compared to wild-type (WT) mice. Citalopram yielded an antidepressant effect without influencing locomotor activity in OE mice but not in WT mice. Reboxetine had no antidepressant-like effect in OE mice, but sex-dependently in WT mice. The two partial agonists, buspirone and S 15535 produced no antidepressant-like activity in both genotypes and sexes, but aberrant motor effects. The antidepressant-like phenotype of male transgenic mice accounts for an involvement of postsynaptic 5-HT(1A)-receptors in the FST behaviour. In addition, the selective over-expression of postsynaptic 5-HT(1A

  9. Pharmacology of the hypothermic response to 5-HT1A receptor activation in humans.

    PubMed

    Lesch, K P; Poten, B; Söhnle, K; Schulte, H M

    1990-01-01

    The selective 5-HT1A receptor ligand ipsapirone (IPS) caused dose-related hypothermia in humans. The response was attenuated by the nonselective 5-HT1/2 receptor antagonist metergoline and was completely antagonized by the nonselective beta-adrenoceptor antagonist pindolol, which interacts stereoselectively with the 5-HT1A receptor. The selective beta 1-adrenergic antagonist betaxolol had no effect. The findings indicate that IPS-induced hypothermia specifically involves activation of (presynaptic) 5-HT1A receptors. Therefore, the hypothermic response to IPS may provide a convenient in vivo paradigma to assess the function of the presynaptic 5-HT receptor in affective disorders and its involvement in the effects of psychotropic drugs. PMID:1980461

  10. Pharmacology of the hypothermic response to 5-HT1A receptor activation in humans.

    PubMed

    Lesch, K P; Poten, B; Söhnle, K; Schulte, H M

    1990-01-01

    The selective 5-HT1A receptor ligand ipsapirone (IPS) caused dose-related hypothermia in humans. The response was attenuated by the nonselective 5-HT1/2 receptor antagonist metergoline and was completely antagonized by the nonselective beta-adrenoceptor antagonist pindolol, which interacts stereoselectively with the 5-HT1A receptor. The selective beta 1-adrenergic antagonist betaxolol had no effect. The findings indicate that IPS-induced hypothermia specifically involves activation of (presynaptic) 5-HT1A receptors. Therefore, the hypothermic response to IPS may provide a convenient in vivo paradigma to assess the function of the presynaptic 5-HT receptor in affective disorders and its involvement in the effects of psychotropic drugs.

  11. Effects of age of serotonin 5-HT2 receptors in cocaine abusers and normal subjects

    SciTech Connect

    Wang, G.J.; Volkow, N.D.; Logan, J.

    1995-05-01

    We measured the effect of age on serotonin 5-HT2 receptor availability and compared it with the effects on dopamine D2 receptors on 19 chronic cocaine abusers (35.2{plus_minus}9.8 years, range 18-54 years old) and 19 age matched normal controls using positron emission tomography (PET) and F-18 N-methylspiperone (NMS). 5-HT2 Receptor availability was measure din frontal (FR), occipital (OC), cingulate (CI) and orbitofrontal (OF) cortices using the ratio of the distribution volume in the region of interest to that in the cerebelium (CB) which is a function of Bmax/Kd. D2 receptor availability in the basal ganglia was measured using the {open_quotes}ratio index{close_quotes} (slope of striatum/CB versus time over 180 min of the scan) which is a function of Bmax. 5-HT2 Receptor availability differed among regions and were as follows: CI>OF>OC>FC.5-HT2 Receptor availability decreased significantly with age. This effect was more accentuated for 5-HT2 receptor availability in FR than in OC(df=1, p<0.025). Striatal dopamine D2 receptors were also found to decrease significantly with age (r=0.63, p<0.007). In a given subject, D2 receptor availability was significantly correlated with 5-HT2 receptor availability in FR (r=0.51, p<0.035) but not in OC. The values for 5-HT2 receptor availability were not different in normal subjects and cocaine abusers. These results document a decline in 5-HT2 and D2 receptors with age and document an association between frontal 5-HT2 and striatal D2 receptor availability. These results did not show any changes in 5-HT2 receptor availability in cocaine abusers as compared to control subjects.

  12. Effect of peripheral 5-HT on glucose and lipid metabolism in wether sheep.

    PubMed

    Watanabe, Hitoshi; Saito, Ryo; Nakano, Tatsuya; Takahashi, Hideyuki; Takahashi, Yu; Sumiyoshi, Keisuke; Sato, Katsuyoshi; Chen, Xiangning; Okada, Natsumi; Iwasaki, Shunsuke; Harjanti, Dian W; Sekiguchi, Natsumi; Sano, Hiroaki; Kitazawa, Haruki; Rose, Michael T; Ohwada, Shyuichi; Watanabe, Kouichi; Aso, Hisashi

    2014-01-01

    In mice, peripheral 5-HT induces an increase in the plasma concentrations of glucose, insulin and bile acids, and a decrease in plasma triglyceride, NEFA and cholesterol concentrations. However, given the unique characteristics of the metabolism of ruminants relative to monogastric animals, the physiological role of peripheral 5-HT on glucose and lipid metabolism in sheep remains to be established. Therefore, in this study, we investigated the effect of 5-HT on the circulating concentrations of metabolites and insulin using five 5-HT receptor (5HTR) antagonists in sheep. After fasting for 24 h, sheep were intravenously injected with 5-HT, following which-, plasma glucose, insulin, triglyceride and NEFA concentrations were significantly elevated. In contrast, 5-HT did not affect the plasma cholesterol concentration, and it induced a decrease in bile acid concentrations. Increases in plasma glucose and insulin concentrations induced by 5-HT were attenuated by pre-treatment with Methysergide, a 5HTR 1, 2 and 7 antagonist. Additionally, decreased plasma bile acid concentrations induced by 5-HT were blocked by pre-treatment with Ketanserin, a 5HTR 2A antagonist. However, none of the 5HTR antagonists inhibited the increase in plasma triglyceride and NEFA levels induced by 5-HT. On the other hand, mRNA expressions of 5HTR1D and 1E were observed in the liver, pancreas and skeletal muscle. These results suggest that there are a number of differences in the physiological functions of peripheral 5-HT with respect to lipid metabolism between mice and sheep, though its effect on glucose metabolism appears to be similar between these species.

  13. Role of spinal 5-HT receptors in cutaneous hypersensitivity induced by REM sleep deprivation.

    PubMed

    Wei, Hong; Ma, Ainiu; Wang, Yong-Xiang; Pertovaara, Antti

    2008-06-01

    Previous studies indicate that rapid eye movement (REM) sleep deprivation facilitates pain sensitivity. Since serotoninergic raphe neurons are involved both in regulation of sleep and descending pain modulation, we studied whether spinal 5-HT receptors have a role in sleep deprivation-induced facilitation of pain-related behavior. REM sleep deprivation of 48h was induced by the flower pot method in the rat. The pain modulatory influence of various serotoninergic compounds administered intrathecally was assessed by determining limb withdrawal response to monofilaments. REM sleep deprivation produced a marked hypersensitivity. Sleep deprivation-induced hypersensitivity and normal sensitivity in controls were reduced both by a 5-HT(1A) receptor antagonist (WAY-100635) and a 5-HT(2C) receptor antagonist (RS-102221). An antagonist of the 5-HT(3) receptor (LY-278584) failed to modulate hypersensitivity in sleep-deprived or control animals. Paradoxically, sensitivity in sleep-deprived and control animals was reduced not only by a 5-HT(1A) receptor antagonist but also by a 5-HT(1A) receptor agonist (8-OHDPAT). The results indicate that serotoninergic receptors in the spinal cord have a complex role in the control of sleep-deprivation induced cutaneous hypersensitivity as well as baseline sensitivity in control conditions. While endogenous serotonin acting on 5-HT(1A) and 5-HT(2C) receptors may facilitate mechanical sensitivity in animals with a sleep deprivation-induced hypersensitivity as well as in controls, increased activation of spinal 5-HT(1A) receptors by an exogenous agonist leads to suppression of mechanical sensitivity in both conditions. Spinal 5-HT(3) receptors do not contribute to cutaneous hypersensitivity induced by sleep deprivation.

  14. Involvement of 5-HT(2C) receptors in the anti-immobility effects of antidepressants in the forced swimming test in mice.

    PubMed

    Clenet, F; De Vos, A; Bourin, M

    2001-04-01

    Several recent studies have demonstrated that 5-HT(1A), 5-HT(1B) and 5-HT(3) receptors were implicated in the mechanism of action of antidepressants in the mouse forced swimming test. Despite extensive evidence for a role of 5-HT(2C) receptors in depression, the precise role of these receptors in the effects of clinically established antidepressants was not directly investigated in the mouse forced swimming test. This work was aimed at exploring interactions between several doses of Ro 60-0175, a recently available, full and selective 5-HT(2C) agonist, and antidepressant drugs in the mouse forced swimming test. Spontaneous locomotor activity was measured as an index of intact sensorimotor functions and the dose-effect of Ro 60-0175 alone, as well as interactions with several antidepressants, such as tricyclic antidepressants (imipramine, desipramine and maprotiline) and selective serotonin reuptake inhibitors (paroxetine, citalopram, fluoxetine, fluvoxamine and sertraline), were studied in the mouse forced swimming test. There was no intrinsic antidepressant-like effect of Ro 60-0175, but an impairment in locomotor function was detected when using doses higher than 4 mg/kg in the mouse. There was a synergistic effect of low doses of Ro 60-0175 with sub-active doses of imipramine, paroxetine, citalopram and fluvoxamine; an antagonism between the highest dose of Ro 60-0175 and the active doses of paroxetine and fluoxetine was also detected. There is evidence that 5-HT(2C) receptors may be involved in the action of antidepressants which are able to boost the concentration of serotonin in the synapse, i.e. SSRIs and imipramine

  15. Systemic inflammation alters central 5-HT function as determined by pharmacological MRI

    PubMed Central

    Couch, Yvonne; Martin, Chris J.; Howarth, Clare; Raley, Josie; Khrapitchev, Alexandre A.; Stratford, Michael; Sharp, Trevor; Sibson, Nicola R.; Anthony, Daniel C.

    2013-01-01

    Considerable evidence indicates a link between systemic inflammation and central 5-HT function. This study used pharmacological magnetic resonance imaging (phMRI) to study the effects of systemic inflammatory events on central 5-HT function. Changes in blood oxygenation level dependent (BOLD) contrast were detected in selected brain regions of anaesthetised rats in response to intravenous administration of the 5-HT-releasing agent, fenfluramine (10 mg/kg). Further groups of rats were pre-treated with the bacterial lipopolysaccharide (LPS; 0.5 mg/kg), to induce systemic inflammation, or the selective 5-HT2A receptor antagonist MDL100907 prior to fenfluramine. The resultant phMRI data were investigated further through measurements of cortical 5-HT release (microdialysis), and vascular responsivity, as well as a more thorough investigation of the role of the 5-HT2A receptor in sickness behaviour. Fenfluramine evoked a positive BOLD response in the motor cortex (+ 15.9 ± 2%) and a negative BOLD response in the dorsal raphe nucleus (− 9.9 ± 4.2%) and nucleus accumbens (− 7.7 ± 5.3%). In all regions, BOLD responses to fenfluramine were significantly attenuated by pre-treatment with LPS (p < 0.0001), but neurovascular coupling remained intact, and fenfluramine-evoked 5-HT release was not affected. However, increased expression of the 5-HT2A receptor mRNA and decreased 5-HT2A-dependent behaviour (wet-dog shakes) was a feature of the LPS treatment and may underpin the altered phMRI signal. MDL100907 (0.5 mg/kg), 5-HT2A antagonist, significantly reduced the BOLD responses to fenfluramine in all three regions (p < 0.0001) in a similar manner to LPS. Together these results suggest that systemic inflammation decreases brain 5-HT activity as assessed by phMRI. However, these effects do not appear to be mediated by changes in 5-HT release, but are associated with changes in 5-HT2A-receptor-mediated downstream signalling pathways. PMID:23473937

  16. 5-HT2 Receptor Regulation of Mitochondrial Genes: Unexpected Pharmacological Effects of Agonists and Antagonists.

    PubMed

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

    2016-04-01

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

  17. Pharmacological evidence that 5-HT1D activation induces renal vasodilation by NO pathway in rats.

    PubMed

    García-Pedraza, José-Ángel; García, Mónica; Martín, María-Luisa; Morán, Asunción

    2015-06-01

    5-HT is a powerful vasoconstrictor substance in renal vasculature (mainly by 5-HT₂ activation). Nevertheless, 5-HT is notable for its dual cardiovascular effects, producing both vasodilator and vasoconstrictor actions. This study aimed to investigate whether, behind the predominant serotonergic vasoconstrictor action, THE 5-HT system may exert renal vasodilator actions, and, if so, characterize the 5-HT receptors and possible indirect pathways. Renal perfusion pressure (PP), systemic blood pressure (SBP) and heart rate (HR) measurement in in situ autoperfused rat kidney was determined in phenylephrine infused rats. Intra arterial (i.a.) bolus administration of 5-HT (0.00000125-0.1 μg/kg) decreased renal PP in the presence of a phenylephrine continuous infusion (phenylephrine-infusion group), without modifying SBP or HR. These vasodilator responses were potentiated by 5-HT₂ antagonism (ritanserin, 1 mg/kg i.v.), whereas the responses were abolished by 5-HT₁ /₇ antagonist (methiothepin, 100 μg/kg i.v.) or 5-HT1D antagonist (LY310762, 1 mg/kg i.v.). The i.a. administration (0.00000125 to 0.1 μg/kg) of 5-CT or L-694,247 (5-HT1D agonist) mimicked 5-HT vasodilator effect, while other agonists (1-PBG, α-methyl-5-HT, AS-19 (5-HT₇), 8-OH-DPAT (5-HT1A) or CGS-12066B (5-HT1B)) did not alter baseline haemodynamic variables. L-694,247 vasodilation was abolished by i.v. bolus of antagonists LY310762 (5-HT1D, 1 mg/kg) or L-NAME (nitric oxide, 10 mg/kg), but not by i.v. bolus of indomethacin (cyclooxygenase, 2 mg/kg) or glibenclamide (ATP-dependent K(+) channel, 20 mg/kg). These outcomes suggest that 5-HT1D activation produces a vasodilator effect in the in situ autoperfused kidney of phenylephrine-infusion rats mediated by the NO pathway. PMID:25854421

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

    PubMed

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

    2001-11-01

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

  19. 5-hydroxytryptamine (5-HT) reduces total peripheral resistance during chronic infusion: direct arterial mesenteric relaxation is not involved

    PubMed Central

    2012-01-01

    Serotonin (5-hydroxytryptamine; 5-HT) delivered over 1 week results in a sustained fall in blood pressure in the sham and deoxycorticosterone acetate (DOCA)-salt rat. We hypothesized 5-HT lowers blood pressure through direct receptor-mediated vascular relaxation. In vivo, 5-HT reduced mean arterial pressure (MAP), increased heart rate, stroke volume, cardiac index, and reduced total peripheral resistance during a 1 week infusion of 5-HT (25 µg/kg/min) in the normotensive Sprague Dawley rat. The mesenteric vasculature was chosen as an ideal candidate for the site of 5-HT receptor mediated vascular relaxation given the high percentage of cardiac output the site receives. Real-time RT-PCR demonstrated that mRNA transcripts for the 5-HT2B, 5-HT1B, and 5-HT7 receptors are present in sham and DOCA-salt superior mesenteric arteries. Immunohistochemistry and Western blot validated the presence of the 5-HT2B, 5- HT1B and 5-HT7 receptor protein in sham and DOCA-salt superior mesenteric artery. Isometric contractile force was measured in endothelium-intact superior mesenteric artery and mesenteric resistance arteries in which the contractile 5- HT2A receptor was antagonized. Maximum concentrations of BW-723C86 (5- HT2B agonist), CP 93129 (5-HT1B agonist) or LP-44 (5-HT7 agonist) did not relax the superior mesenteric artery from DOCA-salt rats vs. vehicle. Additionally, 5-HT (10–9 M to 10–5 M) did not cause relaxation in either contracted mesenteric resistance arteries or superior mesenteric arteries from normotensive Sprague- Dawley rats. Thus, although 5-HT receptors known to mediate vascular relaxation are present in the superior mesenteric artery, they are not functional, and are therefore not likely involved in a 5-HT-induced fall in total peripheral resistance and MAP. PMID:22559843

  20. Vagal anandamide signaling via cannabinoid receptor 1 contributes to luminal 5-HT modulation of visceral nociception in rats.

    PubMed

    Feng, Chen-Chen; Yan, Xiu-Juan; Chen, Xin; Wang, Er-Man; Liu, Qing; Zhang, Li-Yan; Chen, Jun; Fang, Jing-Yuan; Chen, Sheng-Liang

    2014-08-01

    Serotonin (5-HT) plays pivotal roles in the pathogenesis of postinfectious irritable bowel syndrome (PI-IBS), and luminal 5-HT time-dependently modulates visceral nociception. We found that duodenal biopsies from PI-IBS patients exhibited increased 5-HT and decreased anandamide levels and that decreased anandamide was associated with abdominal pain severity, indicating a link between 5-HT and endocannabinoid signaling pathways in PI-IBS. To understand this, we investigated the role of endocannabinoids in 5-HT modulation of visceral nociception in a rat model. Acute intraduodenally applied 5-HT attenuated the visceromotor response (VMR) to colorectal distention, and this was reversed by the cannabinoid receptor 1 (CB1) antagonist AM251. Duodenal anandamide (but not 2-arachidonoylglycerol) content was greatly increased after luminal 5-HT treatment. This effect was abrogated by the 5-HT 3 receptor (5-HT3R) antagonist granisetron, which was luminally delivered to preferentially target vagal terminals. Chemical denervation of vagal afferents blocked 5-HT-evoked antinociception and anandamide release. Chronic luminal 5-HT exposure for 5 days increased baseline VMR and VMR post-5-HT (days 4 and 5). Duodenal levels of anandamide and N-acyl-phosphatidylethanolamine-specific phospholipase D (NAPE-PLD, the anandamide-synthesizing enzyme) protein gradually declined from day 1 to 5. The time-dependent effects of 5-HT were abolished by daily granisetron pretreatment. Daily pretreatment with CB1 agonists or anandamide from day 3 attenuated 5-HT-induced hyperalgesia. These data suggest that vagal 5-HT3R-mediated duodenal anandamide release contributes to acute luminal 5-HT-induced antinociception via CB1 signaling, whereas decreased anandamide is associated with hyperalgesia upon chronic 5-HT treatment. Further understanding of peripheral vagal anandamide signaling may provide insights into the mechanisms underlying 5-HT-related IBS.

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

    PubMed

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

    2016-02-01

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

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

    PubMed

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

    2008-02-01

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

  3. Distribution of serotonin 5-HT1A-binding sites in the brainstem and the hypothalamus, and their roles in 5-HT-induced sleep and ingestive behaviors in rock pigeons (Columba livia).

    PubMed

    dos Santos, Tiago Souza; Krüger, Jéssica; Melleu, Fernando Falkenburger; Herold, Christina; Zilles, Karl; Poli, Anicleto; Güntürkün, Onur; Marino-Neto, José

    2015-12-15

    Serotonin 1A receptors (5-HT1ARs), which are widely distributed in the mammalian brain, participate in cognitive and emotional functions. In birds, 5-HT1ARs are expressed in prosencephalic areas involved in visual and cognitive functions. Diverse evidence supports 5-HT1AR-mediated 5-HT-induced ingestive and sleep behaviors in birds. Here, we describe the distribution of 5-HT1ARs in the hypothalamus and brainstem of birds, analyze their potential roles in sleep and ingestive behaviors, and attempt to determine the involvement of auto-/hetero-5-HT1ARs in these behaviors. In 6 pigeons, the anatomical distribution of [(3)H]8-OH-DPAT binding in the rostral brainstem and hypothalamus was examined. Ingestive/sleep behaviors were recorded (1h) in 16 pigeons pretreated with MM77 (a heterosynaptic 5-HT1AR antagonist; 23 or 69 nmol) for 20 min, followed by intracerebroventricular ICV injection of 5-HT (N:8; 150 nmol), 8-OH-DPAT (DPAT, a 5-HT1A,7R agonist, 30 nmol N:8) or vehicle. 5-HT- and DPAT-induced sleep and ingestive behaviors, brainstem 5-HT neuronal density and brain 5-HT content were examined in 12 pigeons, pretreated by ICV with the 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) or vehicle (N:6/group). The distribution of brainstem and diencephalic c-Fos immunoreactivity after ICV injection of 5-HT, DPAT or vehicle (N:5/group) into birds provided with or denied access to water is also described. 5-HT1ARs are concentrated in the brainstem 5-HTergic areas and throughout the periventricular hypothalamus, preoptic nuclei and circumventricular organs. 5-HT and DPAT produced a complex c-Fos expression pattern in the 5-HT1AR-enriched preoptic hypothalamus and the circumventricular organs, which are related to drinking and sleep regulation, but modestly affected c-Fos expression in 5-HTergic neurons. The 5-HT-induced ingestivebehaviors and the 5-HT- and DPAT-induced sleep behaviors were reduced by MM77 pretreatment. 5,7-DHT increased sleep per se, decreased tryptophan

  4. (Phenylpiperazinyl-butyl)oxindoles as selective 5-HT7 receptor antagonists.

    PubMed

    Volk, Balázs; Barkóczy, József; Hegedus, Endre; Udvari, Szabolcs; Gacsályi, István; Mezei, Tibor; Pallagi, Katalin; Kompagne, Hajnalka; Lévay, György; Egyed, András; Hársing, László G; Spedding, Michael; Simig, Gyula

    2008-04-24

    A series of potent 5-hydroxytryptamine 7 (5-HT 7) ligands has been synthesized that contain a 1,3-dihydro-2 H-indol-2-one (oxindole) skeleton. The binding of these compounds to the 5-HT 7 and 5-HT 1A receptors was measured. Despite the structural similarity of these two serotonin receptor subtypes, several derivatives exhibited a high selectivity to the 5-HT 7 receptor. According to the structure-activity relationship observations, compounds unsubstituted at the oxindole nitrogen atom and containing a tetramethylene spacer between the oxindole skeleton and the basic nitrogen atom are the most potent ligands. Concerning the basic group, besides the moieties of the 4-phenylpiperazine type, halophenyl-1,2,3,6-tetrahydropyridines also proved to be 5-HT 7 receptor-ligands. Because of halogen substitution on the aromatic rings, good metabolic stability could be achieved. A representative of the family, 3-{4-[4-(4-chlorophenyl)-piperazin-1-yl]-butyl}-3-ethyl-6-fluoro-1,3-dihydro-2 H-indol-2-one ( 9e') exhibited selective 5-HT 7 antagonist activity ( K i = 0.79 nM). The in vivo pharmacological potencies of these 5-HT 7 receptor-ligands were estimated by the conflict drinking (Vogel) and the light-dark anxiolytic tests.

  5. Central effects of 5-HT on activity of respiratory and hypoglossally innervated muscles in newborn kittens.

    PubMed Central

    Khater-Boidin, J; Rose, D; Duron, B

    1996-01-01

    1. In decerebrate kittens (n = 29), electrical activity was studied in the 3rd intercartilaginous (inspiratory), the 9th internal intercostal (expiratory) and the hypoglossally innervated muscles (geniohyoid m. and sternohyoid m.) evoked by the application of 5-HT (n = 16) or related agents (5-HT1A agonist, 8-OH-DPAT (n = 6) and 5-HT2 agonist, DOI floor of the IVth ventricle. 2. The application of a control solution (n = 2) produced no significant changes either in minute inspiratory frequency (Fi) or in the electrical activity of the muscles studied. Except for these controls, only one trial with one dose of one drug was performed in a given kitten. 3. A dose-related decrease in Fi was observed in response to 5-HT. Low doses (50-500 nmol, n1 = 8) induced a long-lasting bradypnoea; high doses (5000-10,000 nmol, n2 = 8) induced prolonged periods of apnoea. 4. The apnoeas observed in tracheotomized (n = 3) or non-tracheotomized (n2 = 8) kittens were mainly of central origin and linked to the lengthening of expiratory time. The expiratory muscle activation came on with the reinforcement of the activity of hypoglossally innervated muscles. 5. Application of agonists showed that both the 5-HT-dependent modulation of Fi and the effects of 5-HT on the activity of the muscles studied resulted predominantly from activation of 5-HT2 receptors. PMID:8866368

  6. Central effects of 5-HT on activity of respiratory and hypoglossally innervated muscles in newborn kittens.

    PubMed

    Khater-Boidin, J; Rose, D; Duron, B

    1996-08-15

    1. In decerebrate kittens (n = 29), electrical activity was studied in the 3rd intercartilaginous (inspiratory), the 9th internal intercostal (expiratory) and the hypoglossally innervated muscles (geniohyoid m. and sternohyoid m.) evoked by the application of 5-HT (n = 16) or related agents (5-HT1A agonist, 8-OH-DPAT (n = 6) and 5-HT2 agonist, DOI floor of the IVth ventricle. 2. The application of a control solution (n = 2) produced no significant changes either in minute inspiratory frequency (Fi) or in the electrical activity of the muscles studied. Except for these controls, only one trial with one dose of one drug was performed in a given kitten. 3. A dose-related decrease in Fi was observed in response to 5-HT. Low doses (50-500 nmol, n1 = 8) induced a long-lasting bradypnoea; high doses (5000-10,000 nmol, n2 = 8) induced prolonged periods of apnoea. 4. The apnoeas observed in tracheotomized (n = 3) or non-tracheotomized (n2 = 8) kittens were mainly of central origin and linked to the lengthening of expiratory time. The expiratory muscle activation came on with the reinforcement of the activity of hypoglossally innervated muscles. 5. Application of agonists showed that both the 5-HT-dependent modulation of Fi and the effects of 5-HT on the activity of the muscles studied resulted predominantly from activation of 5-HT2 receptors.

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

    PubMed

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

    2013-10-01

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

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

    PubMed

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

    2016-07-15

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

  9. Measuring the serotonin uptake site using (/sup 3/H)paroxetine--a new serotonin uptake inhibitor

    SciTech Connect

    Gleiter, C.H.; Nutt, D.J.

    1988-01-01

    Serotonin is an important neurotransmitter that may be involved in ethanol preference and dependence. It is possible to label the serotonin uptake site in brain using the tricyclic antidepressant imipramine, but this also binds to other sites. We have used the new high-affinity uptake blocker paroxetine to define binding to this site and report it to have advantages over imipramine as a ligand.

  10. 3,4-methylenedioxymethamphetamine increases excitability in the dentate gyrus: role of 5HT2A receptor-induced PGE2 signaling.

    PubMed

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

    2016-03-01

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

  11. Modifications of plasma 5-HT concentrations during the allergic bronchoconstriction in guinea pigs.

    PubMed

    Arreola-Ramírez, José Luis; Vargas, Mario H; Manjarrez-Gutiérrez, Gabriel; Alquicira, Jesús; Gutiérrez, Julio; Córdoba, Guadalupe; Campos-Bedolla, Patricia; Segura-Medina, Patricia

    2013-09-01

    Several contractile mediators involved in the antigen-induced airway obstruction have been identified, but the role of 5-HT (5-hydroxytryptamine or serotonin) has been scantily investigated. In this work, the potential role of 5-HT in the allergic bronchoconstriction was evaluated through a pharmacological approach and plasma 5-HT measurement in blood samples from the right and left ventricles of anesthetized guinea-pigs. Intravenous 5-HT caused a dose-dependent increase of the lung resistance in anesthetized, nonsensitized guinea pigs. Likewise, in sensitized animals the antigenic challenge with ovalbumin also caused a transient bronchoconstriction (356 ± 60% the basal value), which was largely inhibited by the blockade of serotonergic receptors with methiothepin plus tropisetron (134 ± 10%, P = .007). Sensitized animals tended to have plasma 5-HT concentrations higher than nonsensitized controls, and shortly after the peak of the allergic bronchoconstriction the 5-HT levels in the left ventricle (blood flowing out from lungs) tended to be higher than in the right ventricle (blood entering the lungs), although data dispersion precluded the obtaining of statistical significance. Interestingly, the degree of bronchoconstriction highly correlated with the concentrations of 5-HT found in the left ventricle and measured either in platelet-rich plasma (r = 0.97 P = .007) or platelet-poor plasma (r = 0.97, P = .006). After the obstructive response subsided these correlations were lost, but now the degree of bronchoconstriction turned to be correlated with 5-HT concentration in platelet concentrate (r = 0.76, P = .03). In conclusion, our results suggested that 5-HT is actively released from lungs during the antigenic challenge and that this autacoid is involved in the generation of the airway obstruction.

  12. Therapeutic Potential of 5-HT2C Receptor Agonists for Addictive Disorders.

    PubMed

    Higgins, Guy A; Fletcher, Paul J

    2015-07-15

    The neurotransmitter 5-hydroxytryptamine (5-HT; serotonin) has long been associated with the control of a variety of motivated behaviors, including feeding. Much of the evidence linking 5-HT and feeding behavior was obtained from studies of the effects of the 5-HT releaser (dex)fenfluramine in laboratory animals and humans. Recently, the selective 5-HT2C receptor agonist lorcaserin received FDA approval for the treatment of obesity. This review examines evidence to support the use of selective 5-HT2C receptor agonists as treatments for conditions beyond obesity, including substance abuse (particularly nicotine, psychostimulant, and alcohol dependence), obsessive compulsive, and excessive gambling disorder. Following a brief survey of the early literature supporting a role for 5-HT in modulating food and drug reinforcement, we propose that intrinsic differences between SSRI and serotonin releasers may have underestimated the value of serotonin-based pharmacotherapeutics to treat clinical forms of addictive behavior beyond obesity. We then highlight the critical involvement of the 5-HT2C receptor in mediating the effect of (dex)fenfluramine on feeding and body weight gain and the evidence that 5-HT2C receptor agonists reduce measures of drug reward and impulsivity. A recent report of lorcaserin efficacy in a smoking cessation trial further strengthens the idea that 5-HT2C receptor agonists may have potential as a treatment for addiction. This review was prepared as a contribution to the proceedings of the 11th International Society for Serotonin Research Meeting held in Hermanus, South Africa, July 9-12, 2014.

  13. Differential modulation of feline defensive rage behavior in the medial hypothalamus by 5-HT1A and 5-HT2 receptors.

    PubMed

    Hassanain, M; Bhatt, S; Siegel, A

    2003-08-15

    Previous studies have established that the expression of defensive rage behavior in the cat is mediated over reciprocal pathways that link the medial hypothalamus and the dorsolateral quadrant of the midbrain periaqueductal gray matter (PAG). The present study was designed to determine the roles played by 5-HT(1A) and 5-HT(2C) receptors in the medial hypothalamus on the expression of defensive rage behavior elicited from electrical stimulation of the PAG. Monopolar stimulating electrodes were placed in the midbrain PAG from which defensive rage behavior could be elicited by electrical stimulation. During the course of this study, defensive rage was determined by measuring the latency of the "hissing" component of this behavior. Cannula-electrodes were implanted into sites within the medial hypothalamus from which defensive rage behavior could also be elicited by electrical stimulation in order that serotonergic compounds could be microinjected into behaviorally identifiable regions of the hypothalamus at a later time. Microinjections of the 5-HT(1A) receptor agonist 8-OHDPAT (0.1, 1.0 and 3.0 nmol) into the medial hypothalamus suppressed PAG-elicited hissing in a dose-dependent manner. Administration of the 5-HT(1A) antagonist p-MPPI (3.0 nmol) blocked the suppressive effects of 8-OHDPAT upon hissing. The suppressive effects of 8-OHDPAT were specific to defensive rage behavior because this drug (3 nmol) facilitated quiet biting attack. Microinjections of the 5-HT(2C) receptor agonist (+/-)-DOI hydrochloride into the medial hypothalamus (0.5, 1.0, and 3.0 nmol) facilitated the occurrence of PAG-elicited hissing in a dose-dependent manner. In turn, these facilitating effects were blocked by pretreatment with the selective 5-HT(2) antagonist, LY-53,857, which was microinjected into the same medial hypothalamic site. The findings of this study provide evidence that activation of 5-HT(1A) and 5-HT(2) receptors within the medial hypothalamus exert differential modulatory

  14. Differential modulation of feline defensive rage behavior in the medial hypothalamus by 5-HT1A and 5-HT2 receptors.

    PubMed

    Hassanain, M; Bhatt, S; Siegel, A

    2003-08-15

    Previous studies have established that the expression of defensive rage behavior in the cat is mediated over reciprocal pathways that link the medial hypothalamus and the dorsolateral quadrant of the midbrain periaqueductal gray matter (PAG). The present study was designed to determine the roles played by 5-HT(1A) and 5-HT(2C) receptors in the medial hypothalamus on the expression of defensive rage behavior elicited from electrical stimulation of the PAG. Monopolar stimulating electrodes were placed in the midbrain PAG from which defensive rage behavior could be elicited by electrical stimulation. During the course of this study, defensive rage was determined by measuring the latency of the "hissing" component of this behavior. Cannula-electrodes were implanted into sites within the medial hypothalamus from which defensive rage behavior could also be elicited by electrical stimulation in order that serotonergic compounds could be microinjected into behaviorally identifiable regions of the hypothalamus at a later time. Microinjections of the 5-HT(1A) receptor agonist 8-OHDPAT (0.1, 1.0 and 3.0 nmol) into the medial hypothalamus suppressed PAG-elicited hissing in a dose-dependent manner. Administration of the 5-HT(1A) antagonist p-MPPI (3.0 nmol) blocked the suppressive effects of 8-OHDPAT upon hissing. The suppressive effects of 8-OHDPAT were specific to defensive rage behavior because this drug (3 nmol) facilitated quiet biting attack. Microinjections of the 5-HT(2C) receptor agonist (+/-)-DOI hydrochloride into the medial hypothalamus (0.5, 1.0, and 3.0 nmol) facilitated the occurrence of PAG-elicited hissing in a dose-dependent manner. In turn, these facilitating effects were blocked by pretreatment with the selective 5-HT(2) antagonist, LY-53,857, which was microinjected into the same medial hypothalamic site. The findings of this study provide evidence that activation of 5-HT(1A) and 5-HT(2) receptors within the medial hypothalamus exert differential modulatory

  15. Identification of dual active agents targeting 5-HT1A and SERT by combinatorial virtual screening methods.

    PubMed

    Wang, Panpan; Yang, Fengyuan; Yang, Hong; Xu, Xiaofei; Liu, Duo; Xue, Weiwei; Zhu, Feng

    2015-01-01

    Selective serotonin reuptake inhibitors (SSRIs) are most adopted therapeutics marketed for major depression, and the efficacy of which are greatly reduced by their delayed onset of action and undesirable side effects. 5-HT1A receptor partial agonist and SERT inhibitor (SPARI) was proposed as a novel strategy to overcome the shortage of efficacy by a negative feedback control of 5-HT1A receptor. However, only one SPARI (vilazodone) has been approved for clinical use, and none is currently in clinical trial, which demonstrates a strong need for searching more novel SPARIs to facilitate antidepressants discovery. This work applied a combinatorial virtual screening method (CVSM) by integrating multiple tools. Statistic analysis reveals that CVSM surpasses single virtual screening methods in terms of hit rates and enrichment factors. By adopting optimized CVSM, 91 promising dual target leads form 15 scaffolds were identified, and 40% of these scaffolds have already been reported to show antidepressant related therapeutic effects. In sum, CVSM is capable in identifying novel SPARIs from large chemical libraries with extremely low false hit rate. PMID:26406003

  16. Design, Synthesis, and Evaluation of Tetrasubstituted Pyridines as Potent 5-HT2C Receptor Agonists

    PubMed Central

    2015-01-01

    A series of pyrido[3,4-d]azepines that are potent and selective 5-HT2C receptor agonists is disclosed. Compound 7 (PF-04781340) is identified as a suitable lead owing to good 5-HT2C potency, selectivity over 5-HT2B agonism, and in vitro ADME properties commensurate with an orally available and CNS penetrant profile. The synthesis of a novel bicyclic tetrasubstituted pyridine core template is outlined, including rationale to account for the unexpected formation of aminopyridine 13 resulting from an ammonia cascade cyclization. PMID:25815155

  17. 5-HT receptors involved in initiation or modulation of motor patterns: opportunities for drug development.

    PubMed

    Wallis, D I

    1994-08-01

    A clearer understanding of the role of descending systems in motor control can be achieved by using in vitro preparations of mammalian spinal cord that display patterned motor output, together with the use of selective pharmacological agents. It has been suggested that 5-HT is involved in either the initiation or the modulation of certain motor behaviours, and that it acts to enhance or regulate the motor pattern. Most attention has been paid to the locomotor rhythms underlying walking or swimming, and in respiratory pattern generation. In this article, David Wallis discusses the involvement of 5-HT1 and 5-HT2 receptors in these processes and the possible therapeutic relevance.

  18. Mechanism for the acute effects of organophosphate pesticides on the adult 5-HT system

    PubMed Central

    Judge, Sarah J.; Savy, Claire Y.; Campbell, Matthew; Dodds, Rebecca; Gomes, Larissa Kruger; Laws, Grace; Watson, Anna; Blain, Peter G.; Morris, Christopher M.; Gartside, Sarah E.

    2016-01-01

    The neurotransmitter serotonin (5-HT) is involved in mood disorder aetiology and it has been reported that (organophosphate) OP exposure affects 5-HT turnover. The aim of this study was to elucidate the mechanism underlying OP effects on the adult 5-HT system. First, acute in vivo administration of the OP diazinon (0, 1.3, 13 or 39 mg/kg i.p.) to male Hooded Lister rats inhibited the activity of the cholinergic enzyme acetylcholinesterase in blood and in the hippocampus, dorsal raphe nucleus (DRN), striatum and prefrontal cortex. Diazinon-induced cholinesterase inhibition was greatest in the DRN, the brain's major source of 5-HT neurones. Second, acute in vivo diazinon exposure (0 or 39 mg/kg i.p.) increased the basal firing rate of DRN neurones measured ex vivo in brain slices. The excitatory responses of DRN neurones to α1-adrenoceptor or AMPA/kainate receptor activation were not affected by in vivo diazinon exposure but the inhibitory response to 5-HT was attenuated, indicating 5-HT1A autoreceptor down-regulation. Finally, direct application of the diazinon metabolite diazinon oxon to naive rat brain slices increased the firing rate of DRN 5-HT neurones, as did chlorpyrifos-oxon, indicating the effect was not unique to diazinon. The oxon-induced augmentation of firing was blocked by the nicotinic acetylcholine receptor antagonist mecamylamine and the AMPA/kainate glutamate receptor antagonist DNQX. Together these data indicate that 1) acute OP exposure inhibits DRN cholinesterase, leading to acetylcholine accumulation, 2) the acetylcholine activates nicotinic receptors on 5-HT neurones and also on glutamatergic neurones, thus releasing glutamate and activating 5-HT neuronal AMPA/kainate receptors 3) the increase in 5-HT neuronal activity, and resulting 5-HT release, may lead to 5-HT1A autoreceptor down-regulation. This mechanism may be involved in the reported increase in risk of developing anxiety and depression following occupational OP exposure. PMID

  19. Altered photic and non-photic phase shifts in 5-HT(1A) receptor knockout mice.

    PubMed

    Smith, V M; Sterniczuk, R; Phillips, C I; Antle, M C

    2008-12-01

    The mammalian circadian clock located in the suprachiasmatic nucleus (SCN) is thought to be modulated by 5-HT. 5-HT is though to inhibit photic phase shifts by inhibiting the release of glutamate from retinal terminals, as well as by decreasing the responsiveness of retinorecipient cells in the SCN. Furthermore, there is also evidence that 5-HT may underlie, in part, non-photic phase shifts of the circadian system. Understanding the mechanism by which 5-HT accomplishes these goals is complicated by the wide variety of 5-HT receptors found in the SCN, the heterogeneous organization of both the circadian clock and the location of 5-HT receptors, and by a lack of sufficiently selective pharmacological agents for the 5-HT receptors of interest. Genetically modified animals engineered to lack a specific 5-HT receptor present an alternative avenue of investigation to understand how 5-HT regulates the circadian system. Here we examine behavioral and molecular responses to both photic and non-photic stimuli in mice lacking the 5-HT(1A) receptor. When compared with wild-type controls, these mice exhibit larger phase advances to a short late-night light pulse and larger delays to long 12 h light pulses that span the whole subjective night. Fos and mPer1 expression in the retinorecipient SCN is significantly attenuated following late-night light pulses in the 5-HT(1A) knockout animals. Finally, non-photic phase shifts to (+/-)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT) are lost in the knockout animals, while attenuation of the phase shift to the long light pulse due to rebound activity following a wheel lock is unaffected. These findings suggest that the 5-HT(1A) receptor plays an inhibitory role in behavioral phase shifts, a facilitatory role in light-induced gene expression, a necessary role in phase shifts to 8-OH-DPAT, and is not necessary for activity-induced phase advances that oppose photic phase shifts to long light pulses.

  20. Regulator of G-protein signaling 6 (RGS6) promotes anxiety and depression by attenuating serotonin-mediated activation of the 5-HT1A receptor-adenylyl cyclase axis

    PubMed Central

    Stewart, Adele; Maity, Biswanath; Wunsch, Amanda M.; Meng, Fantao; Wu, Qi; Wemmie, John A.; Fisher, Rory A.

    2014-01-01

    Targeting serotonin (5-HT) bioavailability with selective 5-HT reuptake inhibitors (SSRIs) remains the most widely used treatment for mood disorders. However, their limited efficacy, delayed onset of action, and side effects restrict their clinical utility. Endogenous regulator of G-protein signaling (RGS) proteins have been implicated as key inhibitors of 5-HT1ARs, whose activation is believed to underlie the beneficial effects of SSRIs, but the identity of the specific RGS proteins involved remains unknown. We identify RGS6 as the critical negative regulator of 5-HT1AR-dependent antidepressant actions. RGS6 is enriched in hippocampal and cortical neurons, 5-HT1AR-expressing cells implicated in mood disorders. RGS6−/− mice exhibit spontaneous anxiolytic and antidepressant behavior rapidly and completely reversibly by 5-HT1AR blockade. Effects of the SSRI fluvoxamine and 5-HT1AR agonist 8-OH-DPAT were also potentiated in RGS6+/− mice. The phenotype of RGS6−/− mice was associated with decreased CREB phosphorylation in the hippocampus and cortex, implicating enhanced Gαi-dependent adenylyl cyclase inhibition as a possible causative factor in the behavior observed in RGS6−/− animals. Our results demonstrate that by inhibiting serotonergic innervation of the cortical-limbic neuronal circuit, RGS6 exerts powerful anxiogenic and prodepressant actions. These findings indicate that RGS6 inhibition may represent a viable means to treat mood disorders or enhance the efficacy of serotonergic agents.—Stewart, A., Maity, B., Wunsch, A. M., Meng, F., Wu, Q., Wemmie, J. A., Fisher, R. A. Regulator of G-protein signaling 6 (RGS6) promotes anxiety and depression by attenuating serotonin-mediated activation of the 5-HT1A receptor-adenylyl cyclase axis. PMID:24421401

  1. Evidence of 5-HT components in human sperm: implications for protein tyrosine phosphorylation and the physiology of motility

    PubMed Central

    Jiménez-Trejo, Francisco; Tapia-Rodríguez, Miguel; Cerbón, Marco; Kuhn, Donald M; Manjarrez-Gutiérrez, Gabriel; Mendoza-Rodríguez, C Adriana; Picazo, Ofir

    2016-01-01

    Serotonin (5-hydroxytryptamine; C10H12N2O (5-HT)) is produced in the CNS and in some cells of peripheral tissues. In the mammalian male reproductive system, both 5-HT and tryptophan hydroxylase (TPH) have been described in Leydig cells of the testis and in principal cells of the caput epididymis. In capacitated hamster sperm, it has been shown that 5-HT promotes the acrosomal reaction. The aim of this work was to explore the existence of components of the serotoninergic system and their relevance in human sperm physiology. We used both immunocytochemistry and western blot to detect serotoninergic markers such as 5-HT, TPH1, MAOA, 5-HT1B, 5-HT3, and 5HTT; HPLC for TPH enzymatic activity; Computer Assisted Semen Analysis assays to measure sperm motility parameters and pharmacological approaches to show the effect of 5-HT in sperm motility and tyrosine phosphorylation was assessed by western blot. We found the presence of serotoninergic markers (5-HT, TPH1, MAOA, 5-HT1B, 5-HT2A, 5-HT3, 5-HTT, and TPH enzymatic activity) in human sperm. In addition, we observed a significant increase in tyrosine phosphorylation and changes in sperm motility after 5-HT treatment. In conclusion, our data demonstrate the existence of components of a serotoninergic system in human sperm and support the notion for a functional role of 5-HT in mammalian sperm physiology, which can be modulated pharmacologically. PMID:23028123

  2. 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.

  3. The effects of 5-HT on feeding behaviour in mianserin- or cyproheptadine-pretreated rats.

    PubMed

    Mancilla-Díaz, J M; Escartín-Pérez, R E; López-Alonso, V E

    2003-12-01

    We examined the effects of 5-HT on the feeding behaviour patterns of rats pretreated with mianserin (5-HT(1B/2A/1D receptor antagonist) or cyproheptadine (a 5-HT(2c) receptor antagonist), injected into the pariventricular hypothalamus nucleus (PVN). The animals were kept at 21 +/- 1 degrees C with a 12 h light and 12 h dark cycle on a self-selected feeding paradigm, and provided with freely available and separate sources of proteins, carbohydrates, fats and water. The results indicate that the suppressive effect of 5-HT on carbohydrate intake can be blocked by mianserin and cyproheptadine even at the onset of the natural (dark) feeding period; however, this is a distinct blockade in the paradigm of feeding behavior. All of the meal patterns of fat intake and rest remained unaffected.

  4. Fingerprint-based consensus virtual screening towards structurally new 5-HT(6)R ligands.

    PubMed

    Smusz, Sabina; Kurczab, Rafał; Satała, Grzegorz; Bojarski, Andrzej J

    2015-05-01

    Virtual screening towards the search of new 5-HT6R ligands was carried out with three different fingerprints used for molecules representation. Two structurally new compounds were found to be characterized by a significant 5-HT6R activity (Ki of 119 and 670 nM). The compounds do not possess a positive ionizable group in their structures and therefore they belong to the group of atypical, non-basic 5-HT6R ligands. The obtained hits were proved to fit well in the 5-HT6R binding cavity by docking and molecular dynamic simulation experiments. Moreover, an in silico evaluation of the ADMET properties of these compounds predicted their drug-like character. PMID:25866241

  5. Expression of hippocampal serotonin receptors 5-HT2C and 5-HT5A in a rat model of diet-induced obesity supplemented with tryptophan.

    PubMed

    Lopez-Esparza, Sarahi; Berumen, Laura C; Padilla, Karla; Miledi, Ricardo; García-Alcocer, Guadalupe

    2015-05-01

    Food intake regulation is a complex mechanism that involves endogenous substances and central nervous system structures like hypothalamus or even hippocampus. The neurotransmitter serotonin is distinguished as food intake mediator; within its multiples receptors, the 5-HT2C type is characterized by its inhibitory appetite action but there is no information about 5-HT5A receptors involvement in obesity disease. It is also unknown if there are any changes in the receptors expression in rats hippocampus with induced obesity during development through a high energy diet (HED) supplemented with tryptophan (W). To appreciate the receptors expression pattern in the hippocampus, obesity was induced to young Sprague Dawley rats through a HED and supplemented with W. Immunocytochemical and western blot techniques were used to study the receptor distribution and quantify the protein expression. The rats with HED diet developed obesity until week 13 of treatment. The 5-HT2C receptor expression decreased in CA1, CA2, CA3 and DG of HED group; and also in CA2, CA3 and DG for HEDW group. The 5-HT5A receptor expression only decreased in DG for HED group. Variations of the two serotonin receptors subtypes support their potential role in obesity.

  6. Target size analysis of serotonin 5-HT/sub 1/ and 5-HT/sub 2/ receptors in bovine brain membranes

    SciTech Connect

    Nishino, N.; Tanaka, C.

    1985-09-23

    Freeze-dried crude synaptic membranes prepared from bovine cerebral cortex and striatum were exposed to high energy gamma ray from the source of /sup 60/Co. The size of serotonin 5-HT/sub 1/ receptors labeled by (/sup 3/H)serotonin and that of 5-HT/sub 2/ receptors labeled by (/sup 3/H)spiperone or (/sup 3/H)ketanserin was determined by target size analyses. The values were 57,000 daltons, 145,000 daltons and 152,000 daltons for the cerebral cortex and 56,000 daltons, 141,000 daltons and 150,000 daltons for the striatum, respectively. The estimated sizes were deduced by reference to enzyme standards with known molecular masses and which were irradiated in parallel. These results demonstrate that the molecular entities in situ for 5-HT/sub 1/ receptors are distinct from those for 5-HT/sub 2/ receptors, thus supporting data on the existence of two distinct populations of serotonin receptors, hitherto evidenced physiopharmacologically.

  7. 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

  8. Application of quantitative structure-activity relationship models of 5-HT1A receptor binding to virtual screening identifies novel and potent 5-HT1A ligands.

    PubMed

    Luo, Man; Wang, Xiang Simon; Roth, Bryan L; Golbraikh, Alexander; Tropsha, Alexander

    2014-02-24

    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.

  9. Serotonin homeostasis and serotonin receptors as actors of cortical construction: special attention to the 5-HT3A and 5-HT6 receptor subtypes

    PubMed Central

    Vitalis, Tania; Ansorge, Mark S.; Dayer, Alexandre G.

    2013-01-01

    Cortical circuits control higher-order cognitive processes and their function is highly dependent on their structure that emerges during development. The construction of cortical circuits involves the coordinated interplay between different types of cellular processes such as proliferation, migration, and differentiation of neural and glial cell subtypes. Among the multiple factors that regulate the assembly of cortical circuits, 5-HT is an important developmental signal that impacts on a broad diversity of cellular processes. 5-HT is detected at the onset of embryonic telencephalic formation and a variety of serotonergic receptors are dynamically expressed in the embryonic developing cortex in a region and cell-type specific manner. Among these receptors, the ionotropic 5-HT3A receptor and the metabotropic 5-HT6 receptor have recently been identified as novel serotonergic targets regulating different aspects of cortical construction including neuronal migration and dendritic differentiation. In this review, we focus on the developmental impact of serotonergic systems on the construction of cortical circuits and discuss their potential role in programming risk for human psychiatric disorders. PMID:23801939

  10. Effects of polyamine inhibitors on zinc uptake by COMMA-1D mammary epithelial cells

    SciTech Connect

    Allen, J.C.; Haedrich, L.H. )

    1991-03-15

    Zn uptake or transport is stimulated by glucocorticoids in many types of epithelial cells, including the COMMA-1D mouse mammary cell line. The current objective was to determine whether polyamines also mediate glucocorticoid stimulation of Zn-uptake. Initially, cells grown in lactogenic hormone supplemented-media had approximately 65% greater {sup 65}Zn-uptake over 24 h than cells in nonsupplemented growth media (GM). {sup 65}Zn-uptake from HM with 10{sup {minus}5}M methylglyoxal-bis(guanylhydrazone) (MGBG) (s-adenosyl-methionine decarboxylase inhibitor to block polyamine synthesis) added was less than from GM. Exogenous spermidine added to the MGBG-HM media increased {sup 65}Zn-uptake. However, up to 10mM difluoromethylornithine (DFMO), a more specific inhibitor of sperimidine synthesis, had no significant effect on 24-h {sup 65}Zn-uptake by cells in HM. In GM, DFMO caused a slight dose-dependent decrease in {sup 65}Zn-uptake over the range 10{sup {minus}6} to 5 {times} 10{sup 3}M. Also, with 8 h of incubation, DFMO tended to decrease {sup 65}Zn-uptake in HM-stimulated cells. These data cannot yet distinguish between the possibilities that DFMO is inactivated during the 24-h incubation or that the dramatic effects of MGBG on {sup 65}Zn-uptake in these mammary-derived cells is not related to its inhibition of polyamine synthesis. Because COMMA-1D cells alter Zn uptake in response to lactogenic hormones and MGBG, the model system is suitable for further studies of the mechanisms of zinc transport in epithelia.

  11. Iodine Status in Turkish Populations and Exposure to Iodide Uptake Inhibitors

    PubMed Central

    Ozpinar, Aysel; Kelestimur, Fahrettin; Songur, Yildiran; Can, Ozge; Valentin, Liza; Caldwell, Kathleen; Arikan, Ender; Unsal, Ibrahim; Serteser, Mustafa; Inal, Tamer; Erdemgil, Yigit; Coskun, Abdurrahman; Bakirci, Nadi; Sezgin, Ozlem; Blount, Ben

    2014-01-01

    Perchlorate, nitrate, and thiocyanate are competitive inhibitors of the sodium iodide symporter of the thyroid membrane. These inhibitors can decrease iodine uptake by the symporter into the thyroid gland and may disrupt thyroid function. This study assesses iodine status and exposure to iodide uptake inhibitors of non-pregnant and non-lactating adult women living in three different cities in Turkey (Istanbul, Isparta and Kayseri). We measured iodine and iodide uptake inhibitors in 24-hr urines collected from study participants (N = 255). All three study populations were mildly iodine deficient, with median urinary iodine (UI) levels of 77.5 µg/L in Istanbul, 58.8 µg/L in Isparta, and 69.8 µg/L in Kayseri. Perchlorate doses were higher in the study population (median 0.13 µg/kg/day), compared with a reference population (median 0.059 µg/kg/day), but lower than the U.S. EPA reference dose (0.7 µg/kg/day). Urinary thiocyanate levels increased with increasing exposure to tobacco smoke, with non-smokers (268 µg/L) significantly lower than light smokers (1110 µg/L), who were significantly lower than heavy smokers (2410 µg/L). This pilot study provides novel data indicating that study participants were moderately iodine deficient and had higher intakes of the iodide uptake inhibitor perchlorate compared with a reference population. Further investigation is needed to characterize the thyroid impact resulting from iodine deficiency coupled with exposure to iodide uptake inhibitors such as perchlorate, thiocyanate and nitrate. PMID:24505430

  12. Functional expression of the serotonin 5-HT7 receptor in human glioblastoma cell lines

    PubMed Central

    Mahé, Cécile; Bernhard, Michel; Bobirnac, Ionel; Keser, Corinna; Loetscher, Erika; Feuerbach, Dominik; Dev, Kumlesh K; Schoeffter, Philippe

    2004-01-01

    Serotonin 5-HT7 receptors are present in astrocytes. Understanding their role in this type of cell would greatly benefit from the identification of astroglial cell lines expressing this receptor type. The aim of the present study was to assess the expression of native 5-HT7 receptors and 5-HT7 receptor mRNA in a number of human glioblastoma cell lines, by means of cAMP measurements, Western blot analysis and reverse transcriptase–polymerase chain reaction (RT–PCR) analysis. 5-Hydroxytryptamine (5-HT), 5-carboxamidotryptamine (5-CT), 5-methoxytryptamine (5-MeOT) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) induced concentration-dependent stimulations of cAMP accumulation in the human glioblastoma cell lines, U-373 MG, U-138 MG, U-87 MG, DBTRG-05MG, T98G, H4, CCF-STTG1 and Hs 683. The rank order of potency was 5-CT>5-HT=5-MeOT≫8-OH-DPAT. The effect of 5-CT was inhibited in a concentration-dependent manner by the selective 5-HT7 receptor antagonist SB-269970 in all human glioblastoma cells. Schild analyses yielded slope factors close to unity (0.89–1.13) and pA2 values of 8.69–9.05. Western blot analysis revealed the presence of immunoreactive bands corresponding to the human 5-HT7 receptor in extracts of all human glioblastoma cell lines. The presence of the three splice variants of the 5-HT7 receptor (5-HT7(a/b/d)) was visualized by RT–PCR analysis with specific primers in all human glioblastoma cell lines. In conclusion, human glioblastoma cell lines express functional 5-HT7 receptors and the three splice variants of the corresponding mRNA. These cell lines could serve as model systems of native 5-HT7 receptors in glial cells to investigate their putative role in processes like release of neurotrophic factors or inflammatory cytokines. PMID:15339860

  13. Functional expression of the serotonin 5-HT7 receptor in human glioblastoma cell lines.

    PubMed

    Mahé, Cécile; Bernhard, Michel; Bobirnac, Ionel; Keser, Corinna; Loetscher, Erika; Feuerbach, Dominik; Dev, Kumlesh K; Schoeffter, Philippe

    2004-10-01

    Serotonin 5-HT(7) receptors are present in astrocytes. Understanding their role in this type of cell would greatly benefit from the identification of astroglial cell lines expressing this receptor type. The aim of the present study was to assess the expression of native 5-HT(7) receptors and 5-HT(7) receptor mRNA in a number of human glioblastoma cell lines, by means of cAMP measurements, Western blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. 5-Hydroxytryptamine (5-HT), 5-carboxamidotryptamine (5-CT), 5-methoxytryptamine (5-MeOT) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) induced concentration-dependent stimulations of cAMP accumulation in the human glioblastoma cell lines, U-373 MG, U-138 MG, U-87 MG, DBTRG-05MG, T98G, H4, CCF-STTG1 and Hs 683. The rank order of potency was 5-CT>5-HT=5-MeOT>8-OH-DPAT. The effect of 5-CT was inhibited in a concentration-dependent manner by the selective 5-HT(7) receptor antagonist SB-269970 in all human glioblastoma cells. Schild analyses yielded slope factors close to unity (0.89-1.13) and pA(2) values of 8.69-9.05. Western blot analysis revealed the presence of immunoreactive bands corresponding to the human 5-HT(7) receptor in extracts of all human glioblastoma cell lines. The presence of the three splice variants of the 5-HT(7) receptor (5-HT(7(a/b/d))) was visualized by RT-PCR analysis with specific primers in all human glioblastoma cell lines. In conclusion, human glioblastoma cell lines express functional 5-HT(7) receptors and the three splice variants of the corresponding mRNA. These cell lines could serve as model systems of native 5-HT(7) receptors in glial cells to investigate their putative role in processes like release of neurotrophic factors or inflammatory cytokines. PMID:15339860

  14. Desvenlafaxine succinate: A new serotonin and norepinephrine reuptake inhibitor.

    PubMed

    Deecher, Darlene C; Beyer, Chad E; Johnston, Grace; Bray, Jenifer; Shah, S; Abou-Gharbia, M; Andree, Terrance H

    2006-08-01

    The purpose of this study was to characterize a new chemical entity, desvenlafaxine succinate (DVS). DVS is a novel salt form of the isolated major active metabolite of venlafaxine. Competitive radioligand binding assays were performed using cells expressing either the human serotonin (5-HT) transporter (hSERT) or norepinephrine (NE) transporter (hNET) with K(i) values for DVS of 40.2 +/- 1.6 and 558.4 +/- 121.6 nM, respectively. DVS showed weak binding affinity (62% inhibition at 100 microM) at the human dopamine (DA) transporter. Inhibition of [3H]5-HT or [3H]NE uptake by DVS for the hSERT or hNET produced IC50 values of 47.3 +/- 19.4 and 531.3 +/- 113.0 nM, respectively. DVS (10 microM), examined at a large number of nontransporter targets, showed no significant activity. DVS (30 mg/kg orally) rapidly penetrated the male rat brain and hypothalamus. DVS (30 mg/kg orally) significantly increased extracellular NE levels compared with baseline in the male rat hypothalamus but had no effect on DA levels using microdialysis. To mimic chronic selective serotonin reuptake inhibitor treatment and to block the inhibitory 5-HT(1A) autoreceptors, a 5-HT(1A) antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclo hexanecarboxamide maleate salt (WAY-100635) (0.3 mg/kg s.c.), was administered with DVS (30 mg/kg orally). 5-HT increased 78% compared with baseline with no additional increase in NE or DA levels. In conclusion, DVS is a new 5-HT and NE reuptake inhibitor in vitro and in vivo that demonstrates good brain-to-plasma ratios, suggesting utility in a variety of central nervous system-related disorders.

  15. Bidirectional regulation of emotional memory by 5-HT1B receptors involves hippocampal p11.

    PubMed

    Eriksson, T M; Alvarsson, A; Stan, T L; Zhang, X; Hascup, K N; Hascup, E R; Kehr, J; Gerhardt, G A; Warner-Schmidt, J; Arango-Lievano, M; Kaplitt, M G; Ogren, S O; Greengard, P; Svenningsson, P

    2013-10-01

    Cognitive impairments are common in depression and involve dysfunctional serotonin neurotransmission. The 5-HT1B receptor (5-HT(1B)R) regulates serotonin transmission, via presynaptic receptors, but can also affect transmitter release at heterosynaptic sites. This study aimed at investigating the roles of the 5-HT(1B)R, and its adapter protein p11, in emotional memory and object recognition memory processes by the use of p11 knockout (p11KO) mice, a genetic model for aspects of depression-related states. 5-HT(1B)R agonist treatment induced an impairing effect on emotional memory in wild type (WT) mice. In comparison, p11KO mice displayed reduced long-term emotional memory performance. Unexpectedly, 5-HT(1B)R agonist stimulation enhanced memory in p11KO mice, and this atypical switch was reversed after hippocampal adeno-associated virus mediated gene transfer of p11. Notably, 5-HT(1B)R stimulation increased glutamatergic neurotransmission in the hippocampus in p11KO mice, but not in WT mice, as measured by both pre- and postsynaptic criteria. Magnetic resonance spectroscopy demonstrated global hippocampal reductions of inhibitory GABA, which may contribute to the memory enhancement and potentiation of pre- and post-synaptic measures of glutamate transmission by a 5-HT(1B)R agonist in p11KO mice. It is concluded that the level of hippocampal p11 determines the directionality of 5-HT(1B)R action on emotional memory processing and modulates hippocampal functionality. These results emphasize the importance of using relevant disease models when evaluating the role of serotonin neurotransmission in cognitive deficits related to psychiatric disorders.

  16. 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.

  17. The function of 5-HT3 receptors on colonic transit in rats.

    PubMed

    Haga, K; Asano, K; Fukuda, T; Kobayakawa, T

    1995-12-01

    The function of serotonin (5-HT)3 receptors on colonic transit was investigated in unanesthetized rats. The colonic transit was accelerated by 5-HT (10 mg/kg, s.c.), 2-methyl-5-HT (30 mg/kg, s.c.), neostigmine (0.03-0.1 mg/kg, s.c.), corticotropin releasing factor (CRF; 1 microgram intracerebroventricular administration) and restraint stress (for 45 minutes). A potent and selective 5-HT3 receptor antagonist, azasetron (+/-)-N-(1-azabicyclo[2.2.2]oct-3-yl)-6-chloro- 4-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-8-carboxamide monohydrochloride ; 0.01-10 mg/kg, p.o. inhibited the 5-HT-, CRF- and stress-accelerated colonic transit in a dose-dependent manner. Ondansetron (10 mg/kg, p.o.) and granisetron (1 mg/kg, p.o) also inhibited the stress-accelerated colonic transit, but azasetron was more effective than these two drugs. Atropine methylbromide (0.1 mg/kg, s.c.) and tetrodotoxin (0.01 mg/kg, s.c.) inhibited the accelerated colonic transit under stress conditions, but methysergide (10 mg/kg, s.c.), SDZ205-557 (10 mg/kg, s.c.), domperidone (30 mg/kg, p.o.), trimebutine (300 mg/kg, p.o.), did not. Azasetron (10 micrograms) administered intracerebroventricularly did not inhibit the stress-induced acceleration. These results suggest that endogenous 5-HT which is released through stress accelerates the colonic transit via the 5-HT3 receptors and finally a cholinergic mechanism. It is considered that azasetron inhibits colonic transit particularly under stress conditions through the blockade of the peripheral 5-HT3 receptors. Azasetron may improve bowel function in stress-related colonic dysfunction like irritable bowel syndrome. PMID:8653566

  18. SAR of psilocybin analogs: discovery of a selective 5-HT 2C agonist.

    PubMed

    Sard, Howard; Kumaran, Govindaraj; Morency, Cynthia; Roth, Bryan L; Toth, Beth Ann; He, Ping; Shuster, Louis

    2005-10-15

    An SAR study of psilocybin and psilocin derivatives reveals that 1-methylpsilocin is a selective agonist at the h5-HT(2C) receptor. The corresponding phosphate derivative, 1-methylpsilocybin, shows efficacy in an animal model for obsessive-compulsive disorder, as does 4-fluoro-N,N-dimethyltryptamine. These results suggest a new area for development of novel 5-HT(2C) agonists with applications for drug discovery.

  19. Function and Distribution of 5-HT2 Receptors in the Honeybee (Apis mellifera)

    PubMed Central

    Thamm, Markus; Rolke, Daniel; Jordan, Nadine; Balfanz, Sabine; Schiffer, Christian; Baumann, Arnd; Blenau, Wolfgang

    2013-01-01

    Background Serotonin plays a pivotal role in regulating and modulating physiological and behavioral processes in both vertebrates and invertebrates. In the honeybee (Apis mellifera), serotonin has been implicated in division of labor, visual processing, and learning processes. Here, we present the cloning, heterologous expression, and detailed functional and pharmacological characterization of two honeybee 5-HT2 receptors. Methods Honeybee 5-HT2 receptor cDNAs were amplified from brain cDNA. Recombinant cell lines were established constitutively expressing receptor variants. Pharmacological properties of the receptors were investigated by Ca2+ imaging experiments. Quantitative PCR was applied to explore the expression patterns of receptor mRNAs. Results The honeybee 5-HT2 receptor class consists of two subtypes, Am5-HT2α and Am5-HT2β. Each receptor gene also gives rise to alternatively spliced mRNAs that possibly code for truncated receptors. Only activation of the full-length receptors with serotonin caused an increase in the intracellular Ca2+ concentration. The effect was mimicked by the agonists 5-methoxytryptamine and 8-OH-DPAT at low micromolar concentrations. Receptor activities were blocked by established 5-HT receptor antagonists such as clozapine, methiothepin, or mianserin. High transcript numbers were detected in exocrine glands suggesting that 5-HT2 receptors participate in secretory processes in the honeybee. Conclusions This study marks the first molecular and pharmacological characterization of two 5-HT2 receptor subtypes in the same insect species. The results presented should facilitate further attempts to unravel central and peripheral effects of serotonin mediated by these receptors. PMID:24324783

  20. Bidirectional regulation of emotional memory by 5-HT1B receptors involves hippocampal p11

    PubMed Central

    Eriksson, T M; Alvarsson, A; Stan, T L; Zhang, X; Hascup, K N; Hascup, E R; Kehr, J; Gerhardt, G A; Warner-Schmidt, J; Arango-Lievano, M; Kaplitt, M G; Ögren, S O; Greengard, P; Svenningsson, P

    2013-01-01

    Cognitive impairments are common in depression and involve dysfunctional serotonin neurotransmission. The 5-HT1B receptor (5-HT1BR) regulates serotonin transmission, via presynaptic receptors, but can also affect transmitter release at heterosynaptic sites. This study aimed at investigating the roles of the 5-HT1BR, and its adapter protein p11, in emotional memory and object recognition memory processes by the use of p11 knockout (p11KO) mice, a genetic model for aspects of depression-related states. 5-HT1BR agonist treatment induced an impairing effect on emotional memory in wild type (WT) mice. In comparison, p11KO mice displayed reduced long-term emotional memory performance. Unexpectedly, 5-HT1BR agonist stimulation enhanced memory in p11KO mice, and this atypical switch was reversed after hippocampal adeno-associated virus mediated gene transfer of p11. Notably, 5-HT1BR stimulation increased glutamatergic neurotransmission in the hippocampus in p11KO mice, but not in WT mice, as measured by both pre- and postsynaptic criteria. Magnetic resonance spectroscopy demonstrated global hippocampal reductions of inhibitory GABA, which may contribute to the memory enhancement and potentiation of pre- and post-synaptic measures of glutamate transmission by a 5-HT1BR agonist in p11KO mice. It is concluded that the level of hippocampal p11 determines the directionality of 5-HT1BR action on emotional memory processing and modulates hippocampal functionality. These results emphasize the importance of using relevant disease models when evaluating the role of serotonin neurotransmission in cognitive deficits related to psychiatric disorders. PMID:23032875

  1. Cannabidiol induces rapid-acting antidepressant-like effects and enhances cortical 5-HT/glutamate neurotransmission: role of 5-HT1A receptors.

    PubMed

    Linge, Raquel; Jiménez-Sánchez, Laura; Campa, Leticia; Pilar-Cuéllar, Fuencisla; Vidal, Rebeca; Pazos, Angel; Adell, Albert; Díaz, Álvaro

    2016-04-01

    Cannabidiol (CBD), the main non-psychotomimetic component of marihuana, exhibits anxiolytic-like properties in many behavioural tests, although its potential for treating major depression has been poorly explored. Moreover, the mechanism of action of CBD remains unclear. Herein, we have evaluated the effects of CBD following acute and chronic administration in the olfactory bulbectomy mouse model of depression (OBX), and investigated the underlying mechanism. For this purpose, we conducted behavioural (open field and sucrose preference tests) and neurochemical (microdialysis and autoradiography of 5-HT1A receptor functionality) studies following treatment with CBD. We also assayed the pharmacological antagonism of the effects of CBD to dissect out the mechanism of action. Our results demonstrate that CBD exerts fast and maintained antidepressant-like effects as evidenced by the reversal of the OBX-induced hyperactivity and anhedonia. In vivo microdialysis revealed that the administration of CBD significantly enhanced serotonin and glutamate levels in vmPFCx in a different manner depending on the emotional state and the duration of the treatment. The potentiating effect upon neurotransmitters levels occurring immediately after the first injection of CBD might underlie the fast antidepressant-like actions in OBX mice. Both antidepressant-like effect and enhanced cortical 5-HT/glutamate neurotransmission induced by CBD were prevented by 5-HT1A receptor blockade. Moreover, adaptive changes in pre- and post-synaptic 5-HT1A receptor functionality were also found after chronic CBD. In conclusion, our findings indicate that CBD could represent a novel fast antidepressant drug, via enhancing both serotonergic and glutamate cortical signalling through a 5-HT1A receptor-dependent mechanism.

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

    PubMed

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

    1995-10-01

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

  3. 5-HT7 receptors are involved in neurogenic dural vasodilatation in an experimental model of migraine.

    PubMed

    Wang, Xiaojuan; Fang, Yannan; Liang, Jianbo; Yan, Miansheng; Hu, Rong; Pan, Xiaoping

    2014-01-01

    Neurogenic dural vasodilation has been demonstrated to play an important role in migraine. 5-HT(7) receptors have been found on trigeminal nerve endings and middle meningeal arteries and demonstrated involved in the dilatation of meningeal arteries. The aim of the present study was to demonstrate whether 5-HT(7) receptors are involved in neurogenic dural vasodilation in migraine. The neurogenic dural vasodilation model of migraine was used in this study. Unilateral electrical stimulation of dura mater was performed in anesthetized male Sprague-Dawley rats. Animals were pretreated with selective 5-HT(7) receptor agonist AS19, 5-HT(7) receptor antagonist SB269970, 5-HT1B/1D receptor agonist sumatriptan, or vehicles. Blood flow of the middle meningeal artery (MMA) was measured by a laser Doppler flowmetry. AS19 significantly increased the basal and stimulated blood flows of the middle meningeal artery following electrical stimulation of dura mater, and its effect was dose dependent at the early stage. SB269970 and sumatriptan significantly reduced the basal and stimulated blood flows of middle meningeal artery. The present study demonstrates for the first time that 5-HT(7) receptors are involved in neurogenic dural vasodilation evoked by electrical stimulation of dura mater and maybe of relevance in the pathophysiology and treatment of migraine.

  4. Serotonin (5-HT) augmentation reduces provoked aggression associated with primary psychopathy traits.

    PubMed

    Fanning, Jennifer R; Berman, Mitchell E; Guillot, Casey R; Marsic, Angelika; McCloskey, Michael S

    2014-06-01

    Psychopathy has long been associated with aggressive behavior; however, the neurochemical underpinnings of this relationship are poorly understood. Serotonin (5-HT) neurotransmitter system abnormalities have been associated with provoked aggression in general. In addition, 5-HT dysregulation has been linked to empathy, a trait that is lacking in individuals who score high on primary psychopathy. The purpose of this study was to determine if 5-HT modulates the relationship between psychopathic traits and aggression. Participants (N = 47) completed a self-report measure of psychopathy and were then administered either 40 mg paroxetine (acutely augmenting 5-HT) or placebo. Aggression was assessed during a competitive reaction-time game in which electric shocks were exchanged with an increasingly provocative fictitious opponent. Results indicated that primary psychopathy (but not secondary psychopathy) was related to aggressive responding to provocation. Moreover, 5-HT augmentation attenuated this effect, supporting the notion that aggressive responding associated with primary psychopathic traits may be due in part to 5-HT dysregulation. PMID:22984854

  5. 5-HT Receptor Antagonism Attenuates the Ischemia-Reperfusion Injury After Rabbit Lung Preservation.

    PubMed

    Arreola-Ramírez, J L; Alquicira-Mireles, J; Morales-Hernández, P E; Vargas, M H; Villalba-Caloca, J; Segura-Medina, P

    2015-01-01

    The success of lung transplantation is threatened by the appearance of ischemia-reperfusion injury, which is characterized by increased vascular permeability. 5-Hydroxytryptamine (5-HT; serotonin) is known to produce microvascular leakage in the systemic circulation, but its possible role in ischemia-reperfusion injury after lung preservation has not been reported. In this work we measured the release of 5-HT during a 24-hour rabbit lung preservation, and the effect of methiothepin (antagonist of the majority of 5-HT receptors) and SB204741 (antagonist of 5-HT2B/2C receptors) on the modified capillary filtration coefficient (mKf,c) was evaluated at the end of this period. Our results showed that the highest release rate of 5-HT occurred during the first 15 minutes after the lung harvesting and progressively decreased in the following time intervals. The baseline mKf,c greatly increased after 24 hours of lung preservation, and this increment was partially reduced by methiothepin and even more by SB204741. We concluded that 5-HT may play an important role in the ischemia-reperfusion process after lung preservation.

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

    PubMed

    Aznar, Susana; Hervig, Mona El-Sayed

    2016-05-01

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

  7. Enhancement of the FGFR1 signaling in the FGFR1-5-HT1A heteroreceptor complex in midbrain raphe 5-HT neuron systems. Relevance for neuroplasticity and depression.

    PubMed

    Borroto-Escuela, Dasiel O; Pérez-Alea, Mileidys; Narvaez, Manuel; Tarakanov, Alexander O; Mudó, Giuseppa; Jiménez-Beristain, Antonio; Agnati, Luigi F; Ciruela, Francisco; Belluardo, Natale; Fuxe, Kjell

    2015-07-31

    New findings show existence of FGFR1-5-HT1A heteroreceptor complexes in 5-HT nerve cells of the dorsal and median raphe nuclei of the rat midbrain and hippocampus. Synergistic receptor-receptor interactions in these receptor complexes indicated their enhancing role in hippocampal plasticity. The existence of FGFR1-5-HT1A heteroreceptor complexes also in midbrain raphe 5-HT nerve cells open up the possibility that antidepressant drugs by increasing extracellular 5-HT levels can cause an activation of the FGF-2/FGFR1 mechanism in these nerve cells as well. Therefore, the agonist modulation of the FGFR1-5-HT1A heteroreceptor complexes and their specific role is now determined in rat medullary raphe RN33B cells and in the caudal midline raphe area of the midbrain rich in 5-HT nerve cells. The combined i.c.v. treatment with FGF-2 and the 5-HT1A agonist 8-OHDPAT synergistically increased FGFR1 and ERK1/2 phosphorylation in the raphe midline area of the midbrain and in the RN33B cells. Cotreatment with FGF2 and the 5-HT1A agonist induced RN33B cell differentiation as seen from development of an increased number and length of extensions per cell and their increased 5-HT immunoreactivity. These signaling and differentiation events were dependent on the receptor interface since they were blocked by incubation with TMV but not by TMII of the 5-HT1A receptor. Taken together, the 5-HT1A autoreceptors by being part of a FGFR1-5-HT1A heteroreceptor complex in the midbrain raphe 5-HT nerve cells appears to have also a trophic role in the central 5-HT neuron systems besides playing a key role in reducing the firing of these neurons.

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

    PubMed Central

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

    2013-01-01

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

  9. Expression of the 5-HT1A Serotonin Receptor in the Hippocampus Is Required for Social Stress Resilience and the Antidepressant-Like Effects Induced by the Nicotinic Partial Agonist Cytisine

    PubMed Central

    Mineur, Yann S; Einstein, Emily B; Bentham, Matthew P; Wigestrand, Mattis B; Blakeman, Sam; Newbold, Sylvia A; Picciotto, Marina R

    2015-01-01

    Nicotinic acetylcholine receptor (nAChR) blockers potentiate the effects of selective serotonin reuptake inhibitors (SSRIs) in some treatment-resistant patients; however, it is not known whether these effects are independent, or whether the two neurotransmitter systems act synergistically. We first determined that the SSRI fluoxetine and the nicotinic partial agonist cytisine have synergistic effects in a mouse model of antidepressant efficacy, whereas serotonin depletion blocked the effects of cytisine. Using a pharmacological approach, we found that the 5-HT1A agonist 8-OH-DPAT also potentiated the antidepressant-like effects of cytisine, suggesting that this subtype might mediate the interaction between the serotonergic and cholinergic systems. The 5-HT1A receptors are located both presynaptically and postsynaptically. We therefore knocked down 5-HT1A receptors in either the dorsal raphe (presynaptic autoreceptors) or the hippocampus (a brain area with high expression of 5-HT1A heteroreceptors sensitive to cholinergic effects on affective behaviors). Knockdown of 5-HT1A receptors in hippocampus, but not dorsal raphe, significantly decreased the antidepressant-like effect of cytisine. This study suggests that serotonin signaling through postsynaptic 5-HT1A receptors in the hippocampus is critical for the antidepressant-like effects of a cholinergic drug and begins to elucidate the molecular mechanisms underlying interactions between the serotonergic and cholinergic systems related to mood disorders. PMID:25288485

  10. Expression of the 5-HT1A serotonin receptor in the hippocampus is required for social stress resilience and the antidepressant-like effects induced by the nicotinic partial agonist cytisine.

    PubMed

    Mineur, Yann S; Einstein, Emily B; Bentham, Matthew P; Wigestrand, Mattis B; Blakeman, Sam; Newbold, Sylvia A; Picciotto, Marina R

    2015-03-01

    Nicotinic acetylcholine receptor (nAChR) blockers potentiate the effects of selective serotonin reuptake inhibitors (SSRIs) in some treatment-resistant patients; however, it is not known whether these effects are independent, or whether the two neurotransmitter systems act synergistically. We first determined that the SSRI fluoxetine and the nicotinic partial agonist cytisine have synergistic effects in a mouse model of antidepressant efficacy, whereas serotonin depletion blocked the effects of cytisine. Using a pharmacological approach, we found that the 5-HT1A agonist 8-OH-DPAT also potentiated the antidepressant-like effects of cytisine, suggesting that this subtype might mediate the interaction between the serotonergic and cholinergic systems. The 5-HT1A receptors are located both presynaptically and postsynaptically. We therefore knocked down 5-HT1A receptors in either the dorsal raphe (presynaptic autoreceptors) or the hippocampus (a brain area with high expression of 5-HT1A heteroreceptors sensitive to cholinergic effects on affective behaviors). Knockdown of 5-HT1A receptors in hippocampus, but not dorsal raphe, significantly decreased the antidepressant-like effect of cytisine. This study suggests that serotonin signaling through postsynaptic 5-HT1A receptors in the hippocampus is critical for the antidepressant-like effects of a cholinergic drug and begins to elucidate the molecular mechanisms underlying interactions between the serotonergic and cholinergic systems related to mood disorders.

  11. The effects of aging and chronic fluoxetine treatment on circadian rhythms and suprachiasmatic nucleus expression of neuropeptide genes and 5-HT1B receptors

    PubMed Central

    Duncan, Marilyn J.; Hester, James M.; Hopper, Jason A.; Franklin, Kathleen M.

    2010-01-01

    Age-related changes in circadian rhythms, including attenuation of photic phase shifts, are associated with changes in the central pacemaker in the suprachiasmatic nucleus (SCN). Aging decreases expression of mRNA for vasoactive intestinal peptide (VIP), a key neuropeptide for rhythm generation and photic phase shifts, and increases expression of serotonin transporters and 5-HT1B receptors, whose activation inhibits these phase shifts. Here we describe studies in hamsters showing that aging decreases SCN expression of mRNA for gastrin-releasing peptide, which also modulates photic phase resetting. Because serotonin innervation trophically supports SCN VIP mRNA expression, and serotonin transporters decrease extracellular serotonin, we predicted that chronic administration of the serotonin-selective reuptake inhibitor, fluoxetine, would attenuate the age-related changes in SCN VIP mRNA expression and 5-HT1B receptors. In situ hybridization studies showed that fluoxetine treatment does not alter SCN VIP mRNA expression, in either age group, at zeitgeber time (ZT)6 or 13 (ZT12 corresponds to lights off). However, receptor autoradiographic studies showed that fluoxetine prevents the age-related increase in SCN 5-HT1B receptors at ZT6, and decreases SCN 5-HT1B receptors in both ages at ZT13. Therefore, aging effects on SCN VIP mRNA and SCN 5-HT1B receptors are differentially regulated; the age-related increase in serotonin transporter sites mediates the latter but not the former. The studies also showed that aging and chronic fluoxetine treatment decrease total daily wheel running without altering the phase of the circadian wheel running rhythm, in contrast to previous reports of phase resetting by acute fluoxetine treatment. PMID:20525077

  12. Blockade of 5-HT3 receptor-mediated currents in dissociated frog sensory neurones by benzoxazine derivative, Y-25130.

    PubMed Central

    Yakushiji, T.; Akaike, N.

    1992-01-01

    1. The effect of Y-25130, ((+-)-N-(1-azabicyclo[2.2.2]oct-3-yl)-6-chloro-4-methyl-3-oxo-3,4-dih ydr o- 2H-1,4-benzoxazine-8-carboxamide hydrochloride), a high affinity 5-hydroxytryptamine3 (5-HT3) receptor ligand, was examined on the 5-HT-induced response in dissociated frog dorsal root ganglion (DRG) neurones by use of the extremely rapid concentration-jump ('concentration-clamp') and the conventional whole-cell patch-clamp techniques. 2. 5-HT induced a rapid transient inward current associated with an increase in membrane conductance at a holding potential of -70 mV. The current amplitude increased sigmoidally as 5-HT concentration increased. The half-maximum value (Ka) and the Hill coefficient estimated from the concentration-response curve were 1.7 x 10(-5) M and 1.7, respectively. 3. The current-voltage (I-V) relationship of 5-HT-induced current (I5-HT) showed inward rectification at potentials more positive than -40 mV. The reversal potential (E5-HT) was -11 mV. The E5-HT value was unaffected by total replacement of intracellular K+ by Cs+, indicating that the 5-HT-gated channels might be large cation channels. 4. Both the activation and inactivation phases of I5-HT were single exponentials. The time constants of activation and inactivation (tau a and tau i) decreased with increasing 5-HT concentration. 5. The 5-HT response was mimicked by a selective 5-HT3 receptor agonist, 2-methyl-5-HT, but the maximum response induced was approximately 25% that of 5-HT.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1472977

  13. 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

  14. Striatal 5-HT6 Receptors Regulate Cocaine Reinforcement in a Pathway-Selective Manner.

    PubMed

    Brodsky, Matthew; Gibson, Alec W; Smirnov, Denis; Nair, Sunila G; Neumaier, John F

    2016-08-01

    The nucleus accumbens (NAc) in the ventral striatum integrates many neurochemical inputs including dopamine and serotonin projections from midbrain nuclei to modulate drug reward. Although D1 and D2 dopamine receptors are differentially expressed in the direct and indirect pathway medium spiny neurons (dMSNs and iMSNs, respectively), 5-HT6 receptors are expressed in both pathways, more strongly than anywhere else in the brain, and are an intriguing target for neuropsychiatric disorders. In the present study, we used viral vectors utilizing dynorphin or enkephalin promoters to drive expression of 5-HT6 receptors or green fluorescent protein (GFP) selectively in the dMSNs or iMSNs of the NAc shell. Rats were then trained to self-administer cocaine. Increased 5-HT6 receptor expression in dMSNs did not change any parameter of cocaine self-administration measured. However, increasing 5-HT6 receptors in iMSNs reduced the amount of cocaine self-administered under fixed-ratio schedules, especially at low doses, increased the time to the first response and the length of the inter-infusion interval, but did not alter motivation as measured by progressive ratio 'break point' analysis. Modeling of cocaine pharmacokinetics in NAc showed that increased 5-HT6 receptors in iMSNs reduced the rat's preferred tissue cocaine concentration at each dose. Finally, increased 5-HT6 receptors in iMSNs facilitated conditioned place preference for a low dose of cocaine. We conclude that 5-HT6 receptors in iMSNs of NAcSh increase the sensitivity to the reinforcing properties of cocaine, particularly at low doses, suggesting that these receptors may be a therapeutic target for the treatment of cocaine addiction. PMID:27032690

  15. Serotonergic modulation in neuropathy induced by oxaliplatin: effect on the 5HT2C receptor.

    PubMed

    Baptista-de-Souza, Daniela; Di Cesare Mannelli, Lorenzo; Zanardelli, Matteo; Micheli, Laura; Nunes-de-Souza, Ricardo Luiz; Canto-de-Souza, Azair; Ghelardini, Carla

    2014-07-15

    Fluoxetine has been shown to be effective in clinical and experimental studies of neuropathic pain. Besides to increase serotonin levels in the synaptic cleft, fluoxetine is able to block the serotonergic 5-HT2C receptor subtype, which in turn has been involved in the modulation of neuropathic pain. This study investigated the effect of repeated treatments with fluoxetine on the neuropathic nociceptive response induced by oxaliplatin and the effects of both treatments on 5-HT2C receptor mRNA expression and protein levels in the rat spinal cord (SC), rostral ventral medulla (RVM), midbrain periaqueductal gray (PAG) and amygdala (Amy). Nociception was assessed by paw-pressure, cold plate and Von Frey tests. Fluoxetine prevented mechanical hypersensitivity and pain threshold alterations induced by oxaliplatin but did not prevent the impairment in weight gain induced by this anticancer drug. Ex vivo analysis revealed that oxaliplatin increased the 5-HT2C receptor mRNA expression and protein levels in the SC and PAG. Similar effects were observed in fluoxetine-treated animals but only within the PAG. While oxaliplatin decreased the 5-HT2C mRNA expression levels in the Amy, fluoxetine increased their protein levels in this area. Fluoxetine impaired the oxaliplatin effects on the 5-HT2C receptor mRNA expression in the SC and Amy and protein levels in the SC. All treatments increased of 5-HT2C receptor mRNA expression and protein levels in the PAG. These results suggest that the effects of fluoxetine on neuropathic pain induced by oxaliplatin are associated with quantitative changes in the 5-HT2C receptors located within important areas of the nociceptive system.

  16. 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

  17. Impact of intracellular domain flexibility upon properties of activated human 5-HT3 receptors*

    PubMed Central

    Kozuska, J L; Paulsen, I M; Belfield, W J; Martin, I L; Cole, D J; Holt, A; Dunn, S M J

    2014-01-01

    Background and Purpose It has been proposed that arginine residues lining the intracellular portals of the homomeric 5-HT3A receptor cause electrostatic repulsion of cation flow, accounting for a single-channel conductance substantially lower than that of the 5-HT3AB heteromer. However, comparison of receptor homology models for wild-type pentamers suggests that salt bridges in the intracellular domain of the homomer may impart structural rigidity, and we hypothesized that this rigidity could account for the low conductance. Experimental Approach Mutations were introduced into the portal region of the human 5-HT3A homopentamer, such that putative salt bridges were broken by neutralizing anionic partners. Single-channel and whole cell currents were measured in transfected tsA201 cells and in Xenopus oocytes respectively. Computational simulations of protein flexibility facilitated comparison of wild-type and mutant receptors. Key Results Single-channel conductance was increased substantially, often to wild-type heteromeric receptor values, in most 5-HT3A mutants. Conversely, introduction of arginine residues to the portal region of the heteromer, conjecturally creating salt bridges, decreased conductance. Gating kinetics varied significantly between different mutant receptors. EC50 values for whole-cell responses to 5-HT remained largely unchanged, but Hill coefficients for responses to 5-HT were usually significantly smaller in mutants. Computational simulations suggested increased flexibility throughout the protein structure as a consequence of mutations in the intracellular domain. Conclusions and Implications These data support a role for intracellular salt bridges in maintaining the quaternary structure of the 5-HT3 receptor and suggest a role for the intracellular domain in allosteric modulation of cooperativity and agonist efficacy. Linked Article This article is commented on by Vardy and Kenakin, pp. 1614–1616 of volume 171 issue 7. To view this commentary

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

    PubMed

    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

  19. Uptake Rate of Cationic Mitochondrial Inhibitor MKT-077 Determines Cellular Oxygen Consumption Change in Carcinoma Cells

    PubMed Central

    Chunta, John L.; Vistisen, Kerry S.; Yazdi, Zeinab; Braun, Rod D.

    2012-01-01

    Objective Since tumor radiation response is oxygen-dependent, radiosensitivity can be enhanced by increasing tumor oxygenation. Theoretically, inhibiting cellular oxygen consumption is the most efficient way to increase oxygen levels. The cationic, rhodacyanine dye-analog MKT-077 inhibits mitochondrial respiration and could be an effective metabolic inhibitor. However, the relationship between cellular MKT-077 uptake and metabolic inhibition is unknown. We hypothesized that rat and human mammary carcinoma cells would take up MKT-077, causing a decrease in oxygen metabolism related to drug uptake. Methods R3230Ac rat breast adenocarcinoma cells were exposed to MKT-077. Cellular MKT-077 concentration was quantified using spectroscopy, and oxygen consumption was measured using polarographic electrodes. MKT-077 uptake kinetics were modeled by accounting for uptake due to both the concentration and potential gradients across the plasma and mitochondrial membranes. These kinetic parameters were used to model the relationship between MKT-077 uptake and metabolic inhibition. MKT-077-induced changes in oxygen consumption were also characterized in MDA-MB231 human breast carcinoma cells. Results Cells took up MKT-077 with a time constant of ∼1 hr, and modeling showed that over 90% of intracellular MKT-077 was bound or sequestered, likely by the mitochondria. The uptake resulted in a rapid decrease in oxygen consumption, with a time constant of ∼30 minutes. Surprisingly the change in oxygen consumption was proportional to uptake rate, not cellular concentration. MKT-077 proved a potent metabolic inhibitor, with dose-dependent decreases of 45–73% (p = 0.003). Conclusions MKT-077 caused an uptake rate-dependent decrease in cellular metabolism, suggesting potential efficacy for increasing tumor oxygen levels and radiosensitivity in vivo. PMID:22616013

  20. Identification of spinal 5-HT sub 3 receptors and their role in the modulation of nociceptive responses in the rat

    SciTech Connect

    Glaum, S.R.

    1988-01-01

    The project consisted of two related studies: (1) the characterization of serotonin binding sites in crude and purified synaptic membranes prepared from the rat spinal cord, and (2) the association of serotonin binding sites with functional 5-HT receptor responses in the modulation of nociceptive information at the level of the spinal cord. The first series of experiments involved the preparation of membranes from the dorsal and ventral halves of the rat spinal cord and the demonstration of specific ({sup 3}H)serotonin binding to these membranes. High affinity binding sites which conformed to the 5-HT{sub 3} subtype were identified in dorsal, but not ventral spinal cord synaptic membranes. These experiments also confirmed the presence of high affinity ({sup 3}H)5-HT binding sites in dorsal spinal cord synaptic membranes of the 5-HT{sub 1} subtype. The second group of studies demonstrated the ability of selective 5-HT{sub 3} antagonists to inhibit the antinociceptive response to intrathecally administered 5-HT, as measured by a change in tail flick and hot plate latencies. Intrathecal pretreatment with the selective 5-HT{sub 3} antagonists ICS 205-930 or MDL 72222 abolished the antinociceptive effects of 5-HT. Furthermore, the selective 5-HT{sub 3} agonist 2-methyl-5-HT mimicked the antinociceptive effects of 5-HT.

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

    PubMed

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

    2014-08-01

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

  2. The Design, Synthesis and Structure-Activity Relationship of Mixed Serotonin, Norepinephrine and Dopamine Uptake Inhibitors

    NASA Astrophysics Data System (ADS)

    Chen, Zhengming; Yang, Ji; Skolnick, Phil

    The evolution of antidepressants over the past four decades has involved the replacement of drugs with a multiplicity of effects (e.g., TCAs) by those with selective actions (i.e., SSRIs). This strategy was employed to reduce the adverse effects of TCAs, largely by eliminating interactions with certain neurotransmitters or receptors. Although these more selective compounds may be better tolerated by patients, selective drugs, specifically SSRIs, are not superior to older drugs in treating depressed patients as measured by response and remission rates. It may be an advantage to increase synaptic levels of both serotonin and norepinephrine, as in the case of dual uptake inhibitors like duloxetine and venlafaxine. An important recent development has been the emergence of the triple-uptake inhibitors (TUIs/SNDRIs), which inhibit the uptake of the three neurotransmitters most closely linked to depression: serotonin, norepinephrine, and dopamine. Preclinical studies and clinical trials indicate that a drug inhibiting the reuptake of all three of these neurotransmitters could produce more rapid onset of action and greater efficacy than traditional antidepressants. This review will detail the medicinal chemistry involved in the design, synthesis and discovery of mixed serotonin, norepinephrine and dopamine transporter uptake inhibitors.

  3. SB 242084, a selective and brain penetrant 5-HT2C receptor antagonist.

    PubMed

    Kennett, G A; Wood, M D; Bright, F; Trail, B; Riley, G; Holland, V; Avenell, K Y; Stean, T; Upton, N; Bromidge, S; Forbes, I T; Brown, A M; Middlemiss, D N; Blackburn, T P

    1997-01-01

    SB 242084 has a high affinity (pKi 9.0) for the cloned human 5-HT2C receptor and 100- and 158-fold selectivity over the closely related cloned human 5-HT2B and 5-HT2A subtypes respectively. SB 242084 had over 100-fold selectivity over a range of other 5-HT, dopamine and adrenergic receptors. In studies of 5-HT-stimulated phosphatidylinositol hydrolysis using SH-SY5Y cells stably expressing the cloned human 5-HT2C receptor, SB 242084 acted as an antagonist with a pKb of 9.3, which closely resembled its corresponding receptor binding affinity. SB 242084 potently inhibited m-chlorophenylpiperazine (mCPP, 7 mgkg i.p. 20 min pre-test)-induced hypolocomotion in rats, a model of in vivo central 5-HT2C receptor function, with an ID50 of 0.11 mg/kg i.p., and 2.0 mg/kg p.o. SB 242084 (0.1-1 mg/kg i.p.) exhibited an anxiolytic-like profile in the rat social interaction test, increasing time spent in social interaction, but having no effect on locomotion. SB 242084 (0.1-1 mg/kg i.p.) also markedly increased punished responding in a rat Geller-Seifter conflict test of anxiety, but had no consistent effect on unpunished responding. A large acute dose of SB 242084 (30 mg/kg p.o.) had no effect on seizure susceptibility in the rat maximal electroshock seizure threshold test. Also, while SB 242084 (2 and 6 mg/kg p.o. 1 hr pre-test) antagonized the hypophagic response to mCPP, neither acute nor subchronic administration of the drug, for 5 days at 2 or 6 mg/kg p.o. twice daily, affected food intake or weight gain. The results suggest that SB 242084 is the first reported selective potent and brain penetrant 5-HT2C receptor antagonist and has anxiolytic-like activity, but does not possess either proconvulsant or hyperphagic properties which are characteristic of mutant mice lacking the 5-HT2C receptor. PMID:9225286

  4. Drug-induced defaecation in rats: role of central 5-HT1A receptors.

    PubMed Central

    Croci, T.; Landi, M.; Bianchetti, A.; Manara, L.

    1995-01-01

    1. We investigated the acute effects of 5-hydroxytryptamine (5-HT), and of the 5-HT1A receptor agonists, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), buspirone and SR 57746A, on rat faecal pellet output and water content. 2. 5-HT, 8-OH-DPAT, buspirone and SR 57746A, a new selective 5-HT1A receptor agonist, displaced [3H]-8-OH-DPAT from specific binding sites in rat hippocampus membranes (Ki, nM; 1.8, 1.2, 15, 3.1 respectively) and stimulated rat defaecation dose-dependently. SR 57746A and buspirone induced 1 g dry weight of faeces at 1.3 and 6.1 mg kg-1, p.o. (AD1) respectively. 8-OH-DPAT and 5-HT stimulated defaecation after s.c. injection (AD1, 0.07 and 7.5 mg kg-1, respectively). All these agents increased faecal water content. 3. The putative 5-HT1A receptor antagonist, pindolol, injected s.c. or i.c.v., significantly reduced the defaecation induced by systemically administered 8-OH-DPAT, buspirone or SR 57746A, but not 5-HT. 4. Pretreatment with p-chlorophenylalanine (i.p.) or 5,7-dihydroxytryptamine (i.c.v.), according to protocols designed to cause either generalized or CNS-limited 5-HT depletion respectively, also reduced the defaecation induced by buspirone or SR 57746A. 5. No specific 5-HT1A binding sites could be labelled by incubating rat colon membranes with [3H]-8-OH-DPAT, and in vitro preparations of rat colon segments showed no response to 8-OH-DPAT or SR 57746A up to 5 microM. 6. After eight days' repeated daily treatment, complete tolerance developed to the stimulant effects of SR 57746A and buspirone on faecal water content, but not on faecal pellet output.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7647978

  5. On the structural and mechanistic basis of function, classification, and ligand design for 5-HT receptors.

    PubMed

    Weinstein, H; Osman, R

    1990-01-01

    We review our results from the first computational simulations of a mechanism by which ligands can activate a 5-HT1A receptor, and relate the findings to information on the structure and function of the authentic receptor. The computational exploration of the recognition and activation mechanisms is carried out inside a protein selected as a model for the receptor based on cognate physicochemical and experimental data. A similar approach is applied to the 5-HT2 receptor. The interaction mechanisms at the two 5-HT receptor subtypes differ in the nature of the forces determining ligand-receptor interactions and the types of receptor activation mechanisms they entail. The main molecular property related to recognition at 5-HT1A receptors was shown to be the directional character of the electrostatic potential generated by the ligands in the molecular region corresponding to the indole in 5-HT. The corresponding recognition site was shown to have properties of a positively-charged (imidazolium) form of the side chain of a His residue. The mechanism of recognition at the 5-HT1A receptor was shown to be electrostatic, and conducive to a triggering of the receptor response through the change in the electronic structure of the imidazolium recognition site when it interacts with an activating ligand (agonist). This effect was shown to induce a proton transfer from the ring to a neighboring residue to which it can be hydrogen-bonded in the resting state. We show how this model for recognition and activation defines in molecular terms the mechanisms underlying the classical pharmacologic properties of agonists, partial agonists, and antagonists. The molecular correlates of pharmacologic efficacy emerge from the calculations of the effect of the ligands on the barriers for proton transfer, and on the energy drive for the proton transfer reaction. A different model is proposed for selective recognition at the 5-HT2 receptors, based on structural details of 5-HT-binding peptides

  6. 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

  7. Cloning and immunoreactivity of the 5-HT1Mac and 5-HT2Mac receptors in the central nervous system of the freshwater prawn Macrobrachium rosenbergii

    PubMed Central

    Vázquez-Acevedo, Nietzell; Reyes-Colón, Dalynés; Ruíz-Rodríguez, Eduardo A.; Rivera, Nilsa M.; Rosenthal, Joshua; Kohn, Andrea B.; Moroz, Leonid L.; Sosa, María A.

    2009-01-01

    Biogenic amines are implicated in several mental disorders, many of which involve social interactions. Simple model systems, such as crustaceans, are often more amenable than vertebrates for studying mechanisms underlying behaviors. Although various cellular responses of biogenic amines have been characterized in crustaceans, the mechanisms linking these molecules to behavior remain largely unknown. Observed effects of serotonin receptor agonists and antagonists in abdomen posture, escape responses, and fighting have led to the suggestion that biogenic amine receptors may play a role in modulating interactive behaviors. As a first step in understanding this potential role of such receptors, we have cloned and fully sequenced two serotonin receptors, 5-HT1Mac and 5-HT2Mac, from the CNS of the freshwater prawn Macrobrachium rosenbergii, and have mapped their CNS immunohistochemical distribution. 5-HT1Mac was found primarily on the membranes of subsets of cells in all CNS ganglia, in fibers that traverse all CNS regions, and in the cytoplasm of a small number of cells in the brain, circum- and subesophageal ganglia (SEG), most of which also appear to contain dopamine. The pattern of 5-HT2Mac immunoreactivity was found to differ significantly, being found mostly in the central neuropil area of all ganglia, in glomeruli of the brain’s olfactory lobes, and in the cytoplasm of a small number of neurons in the SEG, thoracic and some abdominal ganglia. The observed differences in terms of localization, distribution within cells, and intensity of immunoreactive staining throughout the prawn’s CNS suggest that these receptors are likely to play different roles. PMID:19184976

  8. Investigating the Motivational Mechanism of Altered Saline Consumption Following 5-HT1A Manipulation

    PubMed Central

    Caras, Melissa L.; MacKenzie, Kimberly; Rodwin, Benjamin; Katz, Donald B.

    2010-01-01

    The precise role played by serotonin (5-HT) in taste—an issue of great interest given the involvement of serotonin in human sensory and eating disorders—is a matter of considerable debate, perhaps because of the variety of methodologies that have been brought to bear by different researchers. Here, we use multiple methods to reveal the motivational mechanism whereby 5-HT1A receptor activation modulates drinking behavior. Subcutaneous injections of the selective 5-HT1A agonist 8-hydroxy-2-di-n-propylamino-tetralin (8-OH-DPAT), a drug that reduces 5-HT release by acting on presynaptic auto-receptors, dose-dependently increased consumption of 0.45M NaCl in a one-bottle test. In a two-bottle test, however, 8-OH-DPAT-treated animals (30 μg/kg/ml) demonstrated decreased NaCl preference—although our detection of this effect was obscured by adaptation to the drug across days. Rats’ performance in a brief access test confirmed that 8-OH-DPAT decreased preference for saline by both increasing water consumption and decreasing NaCl consumption. Finally, taste reactivity tests demonstrated that the latter result does not reflect decreased NaCl palatability. Overall, the results suggest that 8-OH-DPAT-induced 5-HT hypofunction increases thirst without substantially affecting the palatability of NaCl. PMID:18410179

  9. Improvement of ketamine-induced social withdrawal in rats: the role of 5-HT7 receptors.

    PubMed

    Hołuj, Małgorzata; Popik, Piotr; Nikiforuk, Agnieszka

    2015-12-01

    Social withdrawal, one of the core negative symptoms of schizophrenia, can be modelled in the social interaction (SI) test in rats using N-methyl-D-aspartate receptor glutamate receptor antagonists. We have recently shown that amisulpride, an antipsychotic with a high affinity for serotonin 5-HT7 receptors, reversed ketamine-induced SI deficits in rats. The aim of the present study was to further elucidate the potential involvement of 5-HT7 receptors in the prosocial action of amisulpride. Acute administration of amisulpride (3 mg/kg) and SB-269970 (1 mg/kg), a 5-HT7 receptor antagonist, reversed ketamine-induced social withdrawal, whereas sulpiride (20 or 30 mg/kg) and haloperidol (0.2 mg/kg) were ineffective. The 5-HT7 receptor agonist AS19 (10 mg/kg) abolished the prosocial efficacy of amisulpride (3 mg/kg). The coadministration of an inactive dose of SB-269970 (0.2 mg/kg) showed the prosocial effects of inactive doses of amisulpride (1 mg/kg) and sulpiride (20 mg/kg). The anxiolytic chlordiazepoxide (2.5 mg/kg) and the antidepressant fluoxetine (2.5 mg/kg) were ineffective in reversing ketamine-induced SI deficits. The present study suggests that the antagonism of 5-HT7 receptors may contribute towards the mechanisms underlying the prosocial action of amisulpride. These results may have therapeutic implications for the treatment of negative symptoms in schizophrenia and other disorders characterized by social withdrawal.

  10. Amisulpride promotes cognitive flexibility in rats: the role of 5-HT7 receptors.

    PubMed

    Nikiforuk, Agnieszka; Popik, Piotr

    2013-07-01

    The antagonism of 5-HT7 receptors may contribute to the antidepressant and procognitive actions of the atypical antipsychotic drug, amisulpride. It has been previously demonstrated that the selective 5-HT7 receptor antagonist reversed restraint stress-induced cognitive impairments in a rat model of frontal-dependent attentional set-shifting task (ASST). Therefore, the first aim of the present study was to assess the effectiveness of amisulpride against stress-evoked cognitive inflexibility. The second goal was to elucidate whether the pro-cognitive effect of amisulpride could be due to the compound's action at 5-HT7 receptors. Rats repeatedly exposed (1 h daily for 7 days) to restraint stress demonstrated impaired performance on the extra-dimensional (ED) set-shifting stage of the ASST. Amisulpride (3 mg/kg) given to stressed rats 30 min before testing reversed this restraint-induced cognitive inflexibility and improved ED performance of the unstressed control group. The 5-HT7 receptor agonist, AS19 (10 mg/kg), abolished the pro-cognitive efficacy of amisulpride (3 mg/kg). The present study suggests that the antagonism of 5-HT7 receptors may contribute to the mechanisms underlining the pro-cognitive action of amisulpride. These results may have therapeutic implications in frontal-like deficits associated with stress-related disorders.

  11. Chronic systemic administration of 5-HT produces weight loss in mature adult male rats.

    PubMed

    Edwards, S

    1995-09-01

    Adult male rats were allowed to free-feed until their body weights had stabilised. They were next trained onto a 4 h per day feeding regimen, until further stabilisation occurred. All rats then received saline injections for 5 days, to establish baseline body weights. One group was then injected with 5.0 mg/kg 5-HT daily for 30 days while the other group continued with saline. Progressive and significant weight loss occurred in the drug-treated animals. After 30 days, the 5-HT-treated rats had lost 7.0% of their baseline body weights, whereas the control group had gained 1.3%. At this point, the 5-HT treated rats were switched back to saline injections to investigate rebound effects. Although the group that had received 5-HT treatment showed evidence of rebound weight gain, mean weights at the end of the 10 day rebound period were still 4.5% lower than baseline values. These data clearly indicate that chronic systemic administration of 5-HT can produce considerable weight loss in rats.

  12. Aggression and anxiety in adolescent AAS-treated hamsters: A role for 5HT3 receptors.

    PubMed

    Morrison, Thomas R; Ricci, Lesley A; Melloni, Richard H

    2015-07-01

    Previously, we have shown that anabolic androgenic steroid (AAS) exposure throughout adolescence stimulates offensive aggression while also reducing anxious behaviors during the exposure period. Interestingly, AAS exposure through development correlates with alterations to the serotonin system in regions known to contain 5HT3 receptors that influence the control of both aggression and anxiety. Despite these effects, little is known about whether these separate developmental AAS-induced behavioral alterations occur as a function of a common neuroanatomical locus. To begin to address this question, we localized 5HT3 receptors in regions that have been implicated in aggression and anxiety. To examine the impact these receptors may have on AAS alterations to behavior, we microinjected the 5HT3 agonist mCPBG directly into a region know for its influence over aggressive behavior, the lateral division of the anterior hypothalamus, and recorded alterations to anxious behaviors using the elevated plus maze. AAS exposure primarily reduced the presence of 5HT3 receptors in aggression/anxiety regions. Accordingly, mCPBG blocked the anxiolytic effects of adolescent AAS exposure. These data suggest that the 5HT3 receptor plays a critical role in the circuit modulating developmental AAS-induced changes to both aggressive and anxious behaviors, and further implicates the lateral division of the anterior hypothalamus as an important center for the negative behavioral effects of developmental AAS-exposure.

  13. Palonosetron: a unique 5-HT3-receptor antagonist for the prevention of chemotherapy-induced emesis.

    PubMed

    Grunberg, Steven M; Koeller, James M

    2003-12-01

    Palonosetron (Aloxi) is a 5-HT(3)-receptor antagonist antiemetic indicated for the prevention of acute and delayed nausea and vomiting following moderately emetogenic chemotherapy and for acute nausea and vomiting following highly emetogenic chemotherapy. Although it is the fourth member of this class to enter the US market, palonosetron is distinguished by distinct pharmacological characteristics. It has a higher binding affinity for the 5-HT(3 )receptor and a terminal serum half-life at least four times greater than any other available agent of this class (approximately 40 h). The high affinity and long half-life may explain the persistence of antiemetic effect throughout the delayed emesis risk period. The indications for palonosetron are supported by one dose-ranging study and three large, randomised, Phase III studies that all demonstrated at least equivalent activity (and in some cases, superior activity) compared to other 5-HT(3)-receptor antagonists. In spite of the pharmacological differences, the side effect profile of palonosetron is comparable to that of other 5-HT(3)-receptor antagonists. Palonosetron may prove valuable in combination therapy for delayed emesis and may be an appropriate agent for clinical settings, such as multiple-day chemotherapy, where acute emesis is repeatedly induced. Palonosetron provides a convenience advantage if multiple-day 5-HT(3)-receptor antagonist therapy is anticipated and is a unique addition to the antiemetic armamentarium. PMID:14640928

  14. The Role of Hippocampal 5HT3 Receptors in Harmaline-Induced Memory Deficit

    PubMed Central

    Nasehi, Mohammad

    2015-01-01

    Introduction: The plethora of studies indicated that there is a cross talk relationship between harmaline and serotonergic (5-HT) system on cognitive and non-cognitive behaviors. Thus, the purpose of this study is to assess the effects of hippocampal 5-HT4 receptor on memory acquisition deficit induced by harmaline. Methods: Harmaline was injected peritoneally, while 5-HT4 receptor agonist (RS67333) and antagonist (RS23597-190) were injected intra-hippocampal. A single-trial step-down passive avoidance, open field and tail flick tasks were used for measurement of memory, locomotor activity and pain responses, respectively. Results: The data revealed that pre-training injection of higher dose of harmaline (1 mg/kg), RS67333 (0.5 ng/mouse) and RS23597-190 (0.5 ng/mouse) decreased memory acquisition process in the adult mice. Moreover, concurrent pre-training administration of subthreshold dose of RS67333 (0.005 ng/mouse) or RS23597-190 (0.005 ng/mouse) with subthreshold dose of harmaline (0.5 mg/kg, i.p.) intensify impairment of memory acquisition. All above interventions did not change locomotion and tail flick behaviors. Discussion: The results demonstrated that the synergistic effect between both hippocampal 5-HT4 receptor agonist and antagonist with impairment of memory acquisition induced by harmaline, indicating a modulatory effect for hippocampal 5HT4 receptor on Harmaline induced amnesia. PMID:26904173

  15. In the rat forced swimming test, NA-system mediated interactions may prevent the 5-HT properties of some subacute antidepressant treatments being expressed.

    PubMed

    Rénéric, Jean-Philippe; Bouvard, Manuel; Stinus, Luis

    2002-04-01

    In the rat forced swimming test (FST), reuptake inhibitors selective of either serotonin (5-HT) or noradrenaline (NA) decrease immobility duration, and increase, respectively, swimming and climbing behaviour. In this study, an almost total 6-OHDA-induced NA-depletion prevented the behavioural effects of desipramine, but not fluoxetine. Interestingly, the serotonin/noradrenaline-reuptake-inhibitor milnacipran, as well as a (desipramine+fluoxetine) combination, could produce both swimming and climbing behaviour in NA-lesioned rats, but not in non-lesioned. The new antidepressant mirtazapine, which enhances both 5-HT and NA transmissions, supposedly through the antagonizing of alpha(2)-adrenoreceptors, dose-dependently reduced immobility and increased climbing behaviour. Interestingly, a (mirtazapine+fluoxetine) combination treatment resulted in additive anti-immobility effects and in the summation of fluoxetine-induced swimming with mirtazapine-induced climbing. Taken together, these data suggest that the NA system mediates presynaptic inhibiting interactions on the 5-HT system, that may involve alpha(2)-receptors, and that may limit the efficacy of mixed serotonin/noradrenaline reuptake inhibition in subacute antidepressant treatments.

  16. 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.

  17. The Structure of the Mouse Serotonin 5-HT3 Receptor in Lipid Vesicles.

    PubMed

    Kudryashev, Mikhail; Castaño-Díez, Daniel; Deluz, Cédric; Hassaine, Gherici; Grasso, Luigino; Graf-Meyer, Alexandra; Vogel, Horst; Stahlberg, Henning

    2016-01-01

    The function of membrane proteins is best understood if their structure in the lipid membrane is known. Here, we determined the structure of the mouse serotonin 5-HT3 receptor inserted in lipid bilayers to a resolution of 12 Å without stabilizing antibodies by cryo electron tomography and subtomogram averaging. The reconstruction reveals protein secondary structure elements in the transmembrane region, the extracellular pore, and the transmembrane channel pathway, showing an overall similarity to the available X-ray model of the truncated 5-HT3 receptor determined in the presence of a stabilizing nanobody. Structural analysis of the 5-HT3 receptor embedded in a lipid bilayer allowed the position of the membrane to be determined. Interactions between the densely packed receptors in lipids were visualized, revealing that the interactions were maintained by the short horizontal helices. In combination with methodological improvements, our approach enables the structural analysis of membrane proteins in response to voltage and ligand gating.

  18. 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.

  19. Identification of serotonin 5-HT1A receptor partial agonists in ginger.

    PubMed

    Nievergelt, Andreas; Huonker, Peter; Schoop, Roland; Altmann, Karl-Heinz; Gertsch, Jürg

    2010-05-01

    Animal studies suggest that ginger (Zingiber officinale Roscoe) reduces anxiety. In this study, bioactivity-guided fractionation of a ginger extract identified nine compounds that interact with the human serotonin 5-HT(1A) receptor with significant to moderate binding affinities (K(i)=3-20 microM). [(35)S]-GTP gamma S assays indicated that 10-shogaol, 1-dehydro-6-gingerdione, and particularly the whole lipophilic ginger extract (K(i)=11.6 microg/ml) partially activate the 5-HT(1A) receptor (20-60% of maximal activation). In addition, the intestinal absorption of gingerols and shogaols was simulated and their interactions with P-glycoprotein were measured, suggesting a favourable pharmacokinetic profile for the 5-HT(1A) active compounds. PMID:20363635

  20. Dorsal raphe 5-HT(2C) receptor and GABA networks regulate anxiety produced by cocaine withdrawal.

    PubMed

    Craige, Caryne P; Lewandowski, Stacia; Kirby, Lynn G; Unterwald, Ellen M

    2015-06-01

    The serotonin system is intimately linked to both the mediation of anxiety and long-term effects of cocaine, potentially through interaction of inhibitory 5-HT2C receptor and gamma-aminobutyric acid (GABA) networks. This study characterized the function of the dorsal raphe (DR) 5-HT2C receptor and GABA network in anxiety produced by chronic cocaine withdrawal. C57BL/6 mice were injected with saline or cocaine (15 mg/kg) 3 times daily for 10 days, and tested on the elevated plus maze 30 min, 25 h, or 7 days after the last injection. Cocaine-withdrawn mice showed heightened anxiety-like behavior at 25 h of withdrawal, as compared to saline controls. Anxiety-like behavior was not different when mice were tested 30 min or 7 days after the last cocaine injection. Electrophysiology data revealed that serotonin cells from cocaine-withdrawn mice exhibited increased GABA inhibitory postsynaptic currents (IPSCs) in specific DR subregions dependent on withdrawal time (25 h or 7 d), an effect that was absent in cells from non-withdrawn mice (30 min after the last cocaine injection). Increased IPSC activity was restored to baseline levels following bath application of the 5-HT2C receptor antagonist, SB 242084. In a separate cohort of cocaine-injected mice at 25 h of withdrawal, both global and intra-DR blockade of 5-HT2C receptors prior to elevated plus maze testing attenuated anxiety-like behavior. This study demonstrates that DR 5-HT2C receptor blockade prevents anxiety-like behavior produced by cocaine withdrawal, potentially through attenuation of heightened GABA activity, supporting a role for the 5-HT2C receptor in mediating anxiety produced by cocaine withdrawal.

  1. 5-HT7 receptor activation promotes an increase in TrkB receptor expression and phosphorylation

    PubMed Central

    Samarajeewa, Anshula; Goldemann, Lolita; Vasefi, Maryam S.; Ahmed, Nawaz; Gondora, Nyasha; Khanderia, Chandni; Mielke, John G.; Beazely, Michael A.

    2014-01-01

    The serotonin (5-HT) type 7 receptor is expressed throughout the CNS including the cortex and hippocampus. We have previously demonstrated that the application of 5-HT7 receptor agonists to primary hippocampal neurons and SH-SY5Y cells increases platelet-derived growth factor (PDGF) receptor expression and promotes neuroprotection against N-methyl-D-aspartate-(NMDA)-induced toxicity. The tropomyosin-related kinase B (TrkB) receptor is one of the receptors for brain-derived neurotrophic factor (BDNF) and is associated with neurodevelopmental and neuroprotective effects. Application of LP 12 to primary cerebral cortical cultures, SH-SY5Y cells, as well as the retinal ganglion cell line, RGC-5, increased both the expression of full length TrkB as well as its basal phosphorylation state at tyrosine 816. The increase in TrkB expression and phosphorylation was observed as early as 30 min after 5-HT7 receptor activation. In addition to full-length TrkB, kinase domain-deficient forms may be expressed and act as dominant-negative proteins toward the full length receptor. We have identified distinct patterns of TrkB isoform expression across our cell lines and cortical cultures. Although TrkB receptor expression is regulated by cyclic AMP and Gαs-coupled GPCRs in several systems, we demonstrate that, depending on the model system, pathways downstream of both Gαs and Gα12 are involved in the regulation of TrkB expression by 5-HT7 receptors. Given the number of psychiatric and degenerative diseases associated with TrkB/BDNF deficiency and the current interest in developing 5-HT7 receptor ligands as pharmaceuticals, identifying signaling relationships between these two receptors will aid in our understanding of the potential therapeutic effects of 5-HT7 receptor ligands. PMID:25426041

  2. The 5-HT7 receptor as a potential target for treating drug and alcohol abuse.

    PubMed

    Hauser, Sheketha R; Hedlund, Peter B; Roberts, Amanda J; Sari, Youssef; Bell, Richard L; Engleman, Eric A

    2014-01-01

    Alcohol and drug abuse take a large toll on society and affected individuals. However, very few effective treatments are currently available to treat alcohol and drug addiction. Basic and clinical research has begun to provide some insights into the underlying neurobiological systems involved in the addiction process. Several neurotransmitter pathways have been implicated and distinct reward neurocircuitry have been proposed-including the mesocorticolimbic dopamine (MCL-DA) system and the extended amygdala. The serotonin (5-HT) neurotransmitter system is of particular interest and multiple 5-HT receptors are thought to play significant roles in alcohol and drug self-administration and the development of drug dependence. Among the 5-HT receptors, the 5-HT7 receptor is currently undergoing characterization as a potential target for the treatment of several psychiatric disorders. Although this receptor has received only limited research regarding addictive behaviors, aspects of its neuroanatomical, biochemical, physiological, pharmacological, and behavioral profiles suggest that it could play a key role in the addiction process. For instance, genomic studies in humans have suggested a link between variants in the gene encoding the 5-HT7 receptor and alcoholism. Recent behavioral testing using high-affinity antagonists in mice and preliminary tests with alcohol-preferring rats suggest that this receptor could mediate alcohol consumption and/or reinforcement and play a role in seeking/craving behavior. Interest in the development of new and more selective pharmacological agents for this receptor will aid in examining the 5-HT7 receptor as a novel target for treating addiction. PMID:25628528

  3. 5-HT(1A)-like receptor activation inhibits abstinence-induced methamphetamine withdrawal in planarians.

    PubMed

    Rawls, Scott M; Shah, Hardik; Ayoub, George; Raffa, Robert B

    2010-10-29

    No pharmacological therapy is approved to treat methamphetamine physical dependence, but it has been hypothesized that serotonin (5-HT)-enhancing drugs might limit the severity of withdrawal symptoms. To test this hypothesis, we used a planarian model of physical dependence that quantifies withdrawal as a reduction in planarian movement. Planarians exposed to methamphetamine (10 μM) for 60 min, and then placed (tested) into drug-free water for 5 min, displayed less movement (i.e., withdrawal) than either methamphetamine-naïve planarians tested in water or methamphetamine-exposed planarians tested in methamphetamine. A concentration-related inhibition of withdrawal was observed when methamphetamine-exposed planarians were placed into a solution containing either methamphetamine and 5-HT (0.1-100 μM) or methamphetamine and the 5-HT(1A) receptor agonist 8-hydroxy-N,N-dipropyl-2-aminotetralin (8-OH-DPAT) (10, 20 μM). Planarians with prior methamphetamine exposure displayed enhanced withdrawal when tested in a solution of the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (WAY 100635) (1 μM). Methamphetamine-induced withdrawal was not affected by the 5-HT(2B/2C) receptor agonist meta-chlorophenylpiperazine (m-CPZ) (0.1-20 μM). These results provide pharmacological evidence that serotonin-enhancing drugs inhibit expression of methamphetamine physical dependence in an invertebrate model of withdrawal, possibly through a 5-HT(1A)-like receptor-dependent mechanism.

  4. The 5-HT7 receptor as a potential target for treating drug and alcohol abuse

    PubMed Central

    Hauser, Sheketha R.; Hedlund, Peter B.; Roberts, Amanda J.; Sari, Youssef; Bell, Richard L.; Engleman, Eric A.

    2015-01-01

    Alcohol and drug abuse take a large toll on society and affected individuals. However, very few effective treatments are currently available to treat alcohol and drug addiction. Basic and clinical research has begun to provide some insights into the underlying neurobiological systems involved in the addiction process. Several neurotransmitter pathways have been implicated and distinct reward neurocircuitry have been proposed—including the mesocorticolimbic dopamine (MCL-DA) system and the extended amygdala. The serotonin (5-HT) neurotransmitter system is of particular interest and multiple 5-HT receptors are thought to play significant roles in alcohol and drug self-administration and the development of drug dependence. Among the 5-HT receptors, the 5-HT7 receptor is currently undergoing characterization as a potential target for the treatment of several psychiatric disorders. Although this receptor has received only limited research regarding addictive behaviors, aspects of its neuroanatomical, biochemical, physiological, pharmacological, and behavioral profiles suggest that it could play a key role in the addiction process. For instance, genomic studies in humans have suggested a link between variants in the gene encoding the 5-HT7 receptor and alcoholism. Recent behavioral testing using high-affinity antagonists in mice and preliminary tests with alcohol-preferring rats suggest that this receptor could mediate alcohol consumption and/or reinforcement and play a role in seeking/craving behavior. Interest in the development of new and more selective pharmacological agents for this receptor will aid in examining the 5-HT7 receptor as a novel target for treating addiction. PMID:25628528

  5. 5-HT Obesity Medication Efficacy via POMC Activation is Maintained During Aging

    PubMed Central

    Burke, Luke K.; Doslikova, Barbora; D'Agostino, Giuseppe; Garfield, Alastair S.; Farooq, Gala; Burdakov, Denis; Low, Malcolm J.; Rubinstein, Marcelo; Evans, Mark L.; Billups, Brian

    2014-01-01

    The phenomenon commonly described as the middle-age spread is the result of elevated adiposity accumulation throughout adulthood until late middle-age. It is a clinical imperative to gain a greater understanding of the underpinnings of age-dependent obesity and, in turn, how these mechanisms may impact the efficacy of obesity treatments. In particular, both obesity and aging are associated with rewiring of a principal brain pathway modulating energy homeostasis, promoting reduced activity of satiety pro-opiomelanocortin (POMC) neurons within the arcuate nucleus of the hypothalamus (ARC). Using a selective ARC-deficient POMC mouse line, here we report that former obesity medications augmenting endogenous 5-hydroxytryptamine (5-HT) activity d-fenfluramine and sibutramine require ARC POMC neurons to elicit therapeutic appetite-suppressive effects. We next investigated whether age-related diminished ARC POMC activity therefore impacts the potency of 5-HT obesity pharmacotherapies, lorcaserin, d-fenfluramine, and sibutramine and report that all compounds reduced food intake to a comparable extent in both chow-fed young lean (3–5 months old) and middle-aged obese (12–14 months old) male and female mice. We provide a mechanism through which 5-HT anorectic potency is maintained with age, via preserved 5-HT–POMC appetitive anatomical machinery. Specifically, the abundance and signaling of the primary 5-HT receptor influencing appetite via POMC activation, the 5-HT2CR, is not perturbed with age. These data reveal that although 5-HT obesity medications require ARC POMC neurons to achieve appetitive effects, the anorectic efficacy is maintained with aging, findings of clinical significance to the global aging obese population. PMID:25051442

  6. Gaddum and LSD: the birth and growth of experimental and clinical neuropharmacology research on 5-HT in the UK

    PubMed Central

    Green, A R

    2008-01-01

    The vasoconstrictor substance named serotonin was identified as 5-hydroxytryptamine (5-HT) by Maurice Rapport in 1949. In 1951, Rapport gave Gaddum samples of 5-HT substance allowing him to develop a bioassay to both detect and measure the amine. Gaddum and colleagues rapidly identified 5-HT in brain and showed that lysergic acid diethylamide (LSD) antagonized its action in peripheral tissues. Gaddum accordingly postulated that 5-HT might have a role in mood regulation. This review examines the role of UK scientists in the first 20 years following these major discoveries, discussing their role in developing assays for 5-HT in the CNS, identifying the enzymes involved in the synthesis and metabolism of 5-HT and investigating the effect of drugs on brain 5-HT. It reviews studies on the effects of LSD in humans, including Gaddum's self-administration experiments. It outlines investigations on the role of 5-HT in psychiatric disorders, including studies on the effect of antidepressant drugs on the 5-HT concentration in rodent and human brain, and the attempts to examine 5-HT biochemistry in the brains of patients with depressive illness. It is clear that a rather small group of both preclinical scientists and psychiatrists in the UK made major advances in our understanding of the role of 5-HT in the brain, paving the way for much of the knowledge now taken for granted when discussing ways that 5-HT might be involved in the control of mood and the idea that therapeutic drugs used to alleviate psychiatric illness might alter the function of cerebral 5-HT. PMID:18516072

  7. Gaddum and LSD: the birth and growth of experimental and clinical neuropharmacology research on 5-HT in the UK.

    PubMed

    Green, A R

    2008-08-01

    The vasoconstrictor substance named serotonin was identified as 5-hydroxytryptamine (5-HT) by Maurice Rapport in 1949. In 1951, Rapport gave Gaddum samples of 5-HT substance allowing him to develop a bioassay to both detect and measure the amine. Gaddum and colleagues rapidly identified 5-HT in brain and showed that lysergic acid diethylamide (LSD) antagonized its action in peripheral tissues. Gaddum accordingly postulated that 5-HT might have a role in mood regulation. This review examines the role of UK scientists in the first 20 years following these major discoveries, discussing their role in developing assays for 5-HT in the CNS, identifying the enzymes involved in the synthesis and metabolism of 5-HT and investigating the effect of drugs on brain 5-HT. It reviews studies on the effects of LSD in humans, including Gaddum's self-administration experiments. It outlines investigations on the role of 5-HT in psychiatric disorders, including studies on the effect of antidepressant drugs on the 5-HT concentration in rodent and human brain, and the attempts to examine 5-HT biochemistry in the brains of patients with depressive illness. It is clear that a rather small group of both preclinical scientists and psychiatrists in the UK made major advances in our understanding of the role of 5-HT in the brain, paving the way for much of the knowledge now taken for granted when discussing ways that 5-HT might be involved in the control of mood and the idea that therapeutic drugs used to alleviate psychiatric illness might alter the function of cerebral 5-HT.

  8. Reactions between beta-casomorphins-7 and 5-HT2-serotonin receptors.

    PubMed

    Sokolov, O Yu; Pryanikova, N A; Kost, N V; Zolotarev, Yu A; Ryukert, E N; Zozulya, A A

    2005-11-01

    Radioreceptor analysis showed that human beta-casomorphin-7 displaced 3H-spiperone from 5-HT2-serotonin receptors of the rat cerebral frontal cortex: EC50 8 +/- 1 microM. Human and bovine beta-casomorphin-7 dose-dependently blocked serotonin-induced human platelet aggregation: IC50 5 +/- 1 and 20 +/- 4 microM, respectively. It was proved that beta-casomorphins-7 act as 5-HT2-serotonin receptor antagonists; one of the mechanisms of their biological effects is presumably associated with modulation of the serotoninergic system.

  9. Effect of the 5-HT4 receptor and serotonin transporter on visceral hypersensitivity in rats.

    PubMed

    Yan, Chi; Xin-Guang, Liu; Hua-Hong, Wang; Jun-Xia, Li; Yi-Xuan, Li

    2012-10-01

    Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT(4) receptor and the serotonin transporter (SERT) as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times) between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT(4) receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05) and increased 5-HT(4) receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05). Treatment with fluoxetine (10 mg · kg(-1) · day(-1), days 36-42), tegaserod (1 mg · kg(-1) · day(-1), day 43), or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT(4) receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01) but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654). These results indicate that both the 5-HT(4) receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT level.

  10. 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.

  11. 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.

  12. 4-Fluorosulfonylpiperidines: selective 5-HT2A ligands for the treatment of insomnia.

    PubMed

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

    2005-08-15

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

  13. Inhibition of native 5-HT3 receptor-evoked contractions in guinea pig and mouse ileum by antimalarial drugs.

    PubMed

    Kelley, Stephen P; Walsh, Jacqueline; Kelly, Mark C; Muhdar, Simerjyot; Adel-Aziz, Mohammed; Barrett, Iain D; Wildman, Scott S

    2014-09-01

    Quinine, chloroquine and mefloquine are commonly used to treat malaria, however, with associated gastrointestinal (GI) side-effects. These drugs act as antagonists at recombinant 5-HT3 receptors and modulate gut peristalsis. These gastrointestinal side effects may be the result of antagonism at intestinal 5-HT3 receptors. Ileum from male C57BL/6 mice and guinea pigs was mounted longitudinally in organ baths. The concentration-response curves for 5-HT and the selective 5-HT3 agonist 2-Me-5-HT were obtained with 5-HT (pEC50 = 7.57 ± 0.33, 12) more potent (P = 0.004) than 2-Me-5-HT (pEC50 = 5.45 ± 0.58, n = 5) in mouse ileum. There was no difference in potency of 5-HT (pEC50 = 5.42 ± 0.15, n = 8) and 2-Me-5-HT (pIC50 = 5.01 ± 0.55, n = 11) in guinea pig ileum (P > 0.05). Quinine, chloroquine or mefloquine was applied for 10 min and inhibitions prior to submaximal agonist application. In mouse ileum, quinine, chloroquine and mefloquine antagonised 5-HT-induced contractions (pIC50 = 4.9 ± 0.17, n = 7; 4.76 ± 0.14, n = 5; 6.21 ± 0.2, n = 4, correspondingly) with mefloquine most potent (P < 0.05). Quinine, chloroquine and mefloquine antagonised 2-me-5-HT-induced contractions (pIC50 = 6.35 ± 0.11, n = 8; 4.64 ± 0.2, n = 7; 5.11 ± 0.22, n = 6, correspondingly) with quinine most potent (P < 0.05). In guinea-pig ileum, quinine, chloroquine and mefloquine antagonised 5-HT-induced contractions (pIC50 = 5.02 ± 0.15, n = 6; 4.54 ± 0.1, n = 7; 5.32 ± 0.13, n = 5) and 2-me-5-HT-induced contractions (pIC50 = 4.62 ± 0.25, n = 5; 4.56 ± 0.14, n = 6; 5.67 ± 0.12, n = 4) with chloroquine least potent against 5-HT and mefloquine most potent against 2-me-5-HT (P < 0.05). These results support previous studies identifying anti-malarial drugs as antagonists at recombinant 5-HT3 receptors and may also demonstrate the ability of these drugs to influence native 5-HT3 receptor-evoked contractile responses which may account for their associated GI side-effects. PMID:24886883

  14. 5-HT2C Receptor Desensitization Moderates Anxiety in 5-HTT Deficient Mice: From Behavioral to Cellular Evidence

    PubMed Central

    Martin, Cédric BP; Martin, Vincent S.; Trigo, José M.; Chevarin, Caroline; Maldonado, Rafael; Fink, Latham H.; Cunningham, Kathryn A.; Hamon, Michel; Lanfumey, Laurence

    2015-01-01

    Background: Desensitization and blockade of 5-HT2C receptors (5-HT2CR) have long been thought to be central in the therapeutic action of antidepressant drugs. However, besides behavioral pharmacology studies, there is little in vivo data documenting antidepressant-induced 5-HT2CR desensitization in specific brain areas. Methods: Mice lacking the 5-HT reuptake carrier (5-HTT-/-) were used to model the consequences of chronic 5-HT reuptake inhibition with antidepressant drugs. The effect of this mutation on 5-HT2CR was evaluated at the behavioral (social interaction, novelty-suppressed feeding, and 5-HT2CR–induced hypolocomotion tests), the neurochemical, and the cellular (RT-qPCR, mRNA editing, and c-fos–induced expression) levels. Results: Although 5-HTT-/- mice had an anxiogenic profile in the novelty-suppressed feeding test, they displayed less 5-HT2CR–mediated anxiety in response to the agonist m-chlorophenylpiperazine in the social interaction test. In addition, 5-HT2CR–mediated inhibition of a stress-induced increase in 5-HT turnover, measured in various brain areas, was markedly reduced in 5-HTT-/- mutants. These indices of tolerance to 5-HT2CR stimulation were associated neither with altered levels of 5-HT2CR protein and mRNA nor with changes in pre-mRNA editing in the frontal cortex. However, basal c-fos mRNA production in cells expressing 5-HT2CR was higher in 5-HTT-/- mutants, suggesting an altered basal activity of these cells following sustained 5-HT reuptake carrier inactivation. Furthermore, the increased c-fos mRNA expression in 5-HT2CR–like immune-positive cortical cells observed in wild-type mice treated acutely with the 5-HT2CR agonist RO-60,0175 was absent in 5-HTT-/- mutants. Conclusions: Such blunted responsiveness of the 5-HT2CR system, observed at the cell signaling level, probably contributes to the moderation of the anxiety phenotype in 5-HTT-/- mice. PMID:25522398

  15. Anorectic activities of serotonin uptake inhibitors: correlation with their potencies at inhibiting serotonin uptake in vivo and /sup 3/H-mazindol binding in vitro

    SciTech Connect

    Angel, I.; Taranger, M.A.; Claustre, Y.; Scatton, B.; Langer, S.Z.

    1988-01-01

    The mechanism of anorectic action of several serotonin uptake inhibitors was investigated by comparing their anorectic potencies with several biochemical and pharmacological properties and in reference to the novel compound SL 81.0385. The anorectic effect of the potent serotonin uptake inhibitor SL 81.0385 was potentiated by pretreatment with 5-hydroxytryptophan and blocked by the serotonin receptor antagonist metergoline. A good correlation was obtained between the ED/sub 50/ values of anorectic action and the ED/sub 50/ values of serotonin uptake inhibition in vivo (but not in vitro) for several specific serotonin uptake inhibitors. Most of the drugs tested displaced (/sup 3/H)-mazindol from its binding to the anorectic recognition site in the hypothalamus, except the pro-drug zimelidine which was inactive. Excluding zimelidine, a good correlation was obtained between the affinities of these drugs for (/sup 3/H)-mazindol binding and their anorectic action indicating that their anorectic activity may be associated with an effect mediated through this site. Taken together these results suggest that the anorectic action of serotonin uptake inhibitors is directly associated to their ability to inhibit serotonin uptake and thus increasing the synaptic levels of serotonin. The interactions of these drugs with the anorectic recognition site labelled with (/sup 3/H)-mazindol is discussed in connection with the serotonergic regulation of carbohydrate intake.

  16. The anxiety-like phenotype of 5-HT receptor null mice is associated with genetic background-specific perturbations in the prefrontal cortex GABA-glutamate system.

    PubMed

    Bruening, S; Oh, E; Hetzenauer, A; Escobar-Alvarez, S; Westphalen, R I; Hemmings, H C; Singewald, N; Shippenberg, T; Toth, M

    2006-11-01

    A deficit in the serotonin 5-HT(1A) receptor has been found in panic and post-traumatic stress disorders, and genetic inactivation of the receptor results in an anxiety-like phenotype in mice on both the C57Bl6 and Swiss-Webster genetic backgrounds. Anxiety is associated with increased neuronal activity in the prefrontal cortex and here we describe changes in glutamate and GABA uptake of C57Bl6 receptor null mice. Although these alterations were not present in Swiss-Webster null mice, we have previously reported reductions in GABA(A) receptor expression in these but not in C57Bl6 null mice. This demonstrates that inactivation of the 5-HT(1A) receptor elicits different and genetic background-dependent perturbations in the prefrontal cortex GABA/glutamate system. These perturbations can result in a change in the balance between excitation and inhibition, and indeed both C57Bl6 and Swiss-Webster null mice show signs of increased neuronal excitability. Because neuronal activity in the prefrontal cortex controls the extent of response to anxiogenic stimuli, the genetic background-specific perturbations in glutamate and GABA neurotransmission in C57Bl6 and Swiss-Webster 5-HT(1A) receptor null mice may contribute to their shared anxiety phenotype. Our study shows that multiple strains of genetically altered mice could help us to understand the common and individual features of anxiety.

  17. The effect of urapidil, an alpha-1 adrenoceptor antagonist and a 5-HT1A agonist, on the vascular tone of the porcine coronary and pulmonary arteries, the rat aorta and the human pulmonary artery.

    PubMed

    Bopp, Claire; Auger, Cyril; Diemunsch, Pierre; Schini-Kerth, Valérie

    2016-05-15

    Urapidil (Eupressyl(®)) an antihypertensive drug acting as an α1 antagonist and a 5-HT1A agonist, may be of special interest in the treatment of hypertension associated with preeclamptic toxaemia and hypoxia-induced pulmonary arterial vasoconstriction. However, the effect of urapidil on vascular tone has been poorly investigated. Vascular reactivity was evaluated using pulmonary and coronary arteries from 36 pigs, aortae from 22 rats and 9 human pulmonary artery samples suspended in organ chambers. Concentration-relaxation curves either to urapidil, 5-HT, or the 5-HT1A receptor agonist 8-OH-DPAT were constructed after pre-contraction of rings. Pig pulmonary and coronary artery rings were contracted with U46619, a thromboxane mimetic, rat aortic rings with either endothelin-1 or phenylephrine, and human pulmonary artery rings with U46619 or phenylephrine. Urapidil markedly inhibited phenylephrine-induced contractions in rat aortic rings with and without endothelium with a more pronounced effect observed in rings without endothelium. Both 5-HT and 8-OH-DPAT failed to induce relaxation in rat aortic rings with an intact endothelium. 5-HT, but not urapidil and 8-OH-DPAT, induced a concentration-dependent relaxation in the porcine coronary and pulmonary artery rings with an intact endothelium (P<0.05). 5-HT and phenylephrine but not urapidil caused concentration-dependent contractions in human pulmonary artery rings. The present findings, while confirming that urapidil is a potent inhibitor of α1-adrenoceptor-induced contraction, do not support the role of 5-HT1A receptor activation in the control of the vascular tone of the different types of arteries tested in response to urapidil. In addition, they indicate that urapidil seems to preferentially target arteries with endothelial dysfunction.

  18. Modulation of thyroidal radioiodide uptake by oncological pipeline inhibitors and Apigenin.

    PubMed

    Lakshmanan, Aparna; Scarberry, Daniel; Green, Jill A; Zhang, Xiaoli; Selmi-Ruby, Samia; Jhiang, Sissy M

    2015-10-13

    Targeted radioiodine therapy for thyroid cancer is based on selective stimulation of Na+/I- Symporter (NIS)-mediated radioactive iodide uptake (RAIU) in thyroid cells by thyrotropin. Patients with advanced thyroid cancer do not benefit from radioiodine therapy due to reduced or absent NIS expression. To identify inhibitors that can be readily translated into clinical care, we examined oncological pipeline inhibitors targeting Akt, MEK, PI3K, Hsp90 or BRAF in their ability to increase RAIU in thyroid cells expressing BRAFV600E or RET/PTC3 oncogene. Our data showed that (1) PI3K inhibitor GDC-0941 outperformed other inhibitors in RAIU increase mainly by decreasing iodide efflux rate to a great extent; (2) RAIU increase by all inhibitors was extensively reduced by TGF-β, a cytokine secreted in the invasive fronts of thyroid cancers; (3) RAIU reduction by TGF-β was mainly mediated by NIS reduction and could be reversed by Apigenin, a plant-derived flavonoid; and (4) In the presence of TGF-β, GDC-0941 with Apigenin co-treatment had the highest RAIU level in both BRAFV600E expressing cells and RET/PTC3 expressing cells. Taken together, Apigenin may serve as a dietary supplement along with small molecule inhibitors to improve radioiodine therapeutic efficacy on invasive tumor margins thereby minimizing future metastatic events.

  19. The atypical antipsychotics clozapine and olanzapine promote down-regulation and display functional selectivity at human 5-HT7 receptors

    PubMed Central

    Andressen, K W; Manfra, O; Brevik, C H; Ulsund, A H; Vanhoenacker, P; Levy, F O; Krobert, K A

    2015-01-01

    Background and Purpose Classically, ligands of GPCRs have been classified primarily upon their affinity and efficacy to activate a signal transduction pathway. Recent reports indicate that the efficacy of a particular ligand can vary depending on the receptor-mediated response measured (e.g. activating G proteins, other downstream responses, internalization). Previously, we reported that inverse agonists induce both homo- and heterologous desensitization, similar to agonist stimulation, at the Gs-coupled 5-HT7 receptor. The primary objective of this study was to determine whether different inverse agonists at the 5-HT7 receptor also induce internalization and/or degradation of 5-HT7 receptors. Experimental Approach HEK293 cells expressing 5-HT7(a, b or d) receptors were pre-incubated with 5-HT, clozapine, olanzapine, mesulergine or SB269970 and their effects upon receptor density, AC activity, internalization, recruitment of β-arrestins and lysosomal trafficking were measured. Key Results The agonist 5-HT and three out of four inverse agonists tested increased internalization independently of β-arrestin recruitment. Among these, only the atypical antipsychotics clozapine and olanzapine promoted lysosomal sorting and reduced 5-HT7 receptor density (∼60% reduction within 24 h). Inhibition of lysosomal degradation with chloroquine blocked the clozapine- and olanzapine-induced down-regulation of 5-HT7 receptors. Incubation with SB269970 decreased both 5-HT7(b) constitutive internalization and receptor density but increased 5-HT7(d) receptor density, indicating differential ligand regulation among the 5-HT7 splice variants. Conclusions and Implications Taken together, we found that various ligands differentially activate regulatory processes governing receptor internalization and degradation in addition to signal transduction. Thus, these data extend our understanding of functional selectivity at the 5-HT7 receptor. PMID:25884989

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

    PubMed

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

    2016-10-01

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

  1. Escitalopram attenuates β-amyloid-induced tau hyperphosphorylation in primary hippocampal neurons through the 5-HT1A receptor mediated Akt/GSK-3β pathway.

    PubMed

    Wang, Yan-Juan; Ren, Qing-Guo; Gong, Wei-Gang; Wu, Di; Tang, Xiang; Li, Xiao-Li; Wu, Fang-Fang; Bai, Feng; Xu, Lin; Zhang, Zhi-Jun

    2016-03-22

    Tau hyperphosphorylation is an important pathological feature of Alzheimer's disease (AD). To investigate whether escitalopram could inhibit amyloid-β (Aβ)-induced tau hyperphosphorylation and the underlying mechanisms, we treated the rat primary hippocampal neurons with Aβ1-42 and examined the effect of escitalopram on tau hyperphosphorylation. Results showed that escitalopram decreased Aβ1-42-induced tau hyperphosphorylation. In addition, escitalopram activated the Akt/GSK-3β pathway, and the PI3K inhibitor LY294002 blocked the attenuation of tau hyperphosphorylation induced by escitalopram. Moreover, the 5-HT1A receptor agonist 8-OH-DPAT also activated the Akt/GSK-3β pathway and decreased Aβ1-42-induced tau hyperphosphorylation. Furthermore, the 5-HT1A receptor antagonist WAY-100635 blocked the activation of Akt/GSK-3β pathway and the attenuation of tau hyperphosphorylation induced by escitalopram. Finally, escitalopram improved Aβ1-42 induced impairment of neurite outgrowth and spine density, and reversed Aβ1-42 induced reduction of synaptic proteins. Our results demonstrated that escitalopram attenuated Aβ1-42-induced tau hyperphosphorylation in primary hippocampal neurons through the 5-HT1A receptor mediated Akt/GSK-3β pathway. PMID:26950279

  2. Changes in functional properties and 5-HT modulation above and below a spinal transection in lamprey

    PubMed Central

    Becker, Matthew I.; Parker, David

    2015-01-01

    In addition to the disruption of neural function below spinal cord injuries (SCI), there also can be changes in neuronal properties above and below the lesion site. The relevance of these changes is generally unclear, but they must be understood if we are to provide rational interventions. Pharmacological approaches to improving locomotor function have been studied extensively, but it is still unclear what constitutes an optimal approach. Here, we have used the lamprey to compare the modulatory effects of 5-HT and lesion-induced changes in cellular and synaptic properties in unlesioned and lesioned animals. While analyses typically focus on the sub-lesion spinal cord, we have also examined effects above the lesion to see if there are changes here that could potentially contribute to the functional recovery. Cellular and synaptic properties differed in unlesioned and lesioned spinal cords and above and below the lesion site. The cellular and synaptic modulatory effects of 5-HT also differed in lesioned and unlesioned animals, again in region-specific ways above and below the lesion site. A role for 5-HT in promoting recovery was suggested by the potential for improvement in locomotor activity when 5-HT was applied to poorly recovered animals, and by the consistent failure of animals to recover when they were incubated in PCPA to deplete 5-HT. However, PCPA did not affect swimming in animals that had already recovered, suggesting a difference in 5-HT effects after lesioning. These results show changes in 5-HT modulation and cellular and synaptic properties after recovery from a spinal cord transection. Importantly, effects are not confined to the sub-lesion spinal cord but also occur above the lesion site. This suggests that the changes may not simply reflect compensatory responses to the loss of descending inputs, but reflect the need for co-ordinated changes above and below the lesion site. The changes in modulatory effects should be considered in pharmacological

  3. Pharmacological, neurochemical, and behavioral profile of JB-788, a new 5-HT1A agonist.

    PubMed

    Picard, M; Morisset, S; Cloix, J F; Bizot, J C; Guerin, M; Beneteau, V; Guillaumet, G; Hevor, T K

    2010-09-01

    A novel pyridine derivative, 8-{4-[(6-methoxy-2,3-dihydro-[1,4]dioxino[2,3-b]pyridine-3-ylmethyl)-amino]-butyl}-8-aza-spiro[4.5]decane-7,9-dione hydrochloride, termed JB-788, was designed to selectively target 5-HT(1A) receptors. In the present study, the pharmacological profile of JB-788 was characterized in vitro using radioligands binding tests and in vivo using neurochemical and behavioural experiments. JB-788 bound tightly to human 5-HT(1A) receptor expressed in human embryonic kidney 293 (HEK-293) cells with a K(i) value of 0.8 nM. Its binding affinity is in the same range as that observed for the (+/-)8-OH-DPAT, a reference 5HT(1A) agonist compound. Notably, JB-788 only bound weakly to 5-HT(1B) or 5-HT(2A) receptors and moreover the drug displayed only weak or indetectable binding to muscarinic, alpha(2), beta(1) and beta(2) adrenergic receptors, or dopaminergic D(1) receptors. JB-788 was found to display substantial binding affinity for dopaminergic D(2) receptors and, to a lesser extend to alpha(1) adrenoreceptors. JB-788 dose-dependently decreased forskolin-induced cAMP accumulation in HEK cells expressing human 5-HT(1A), thus acting as a potent 5-HT(1A) receptor agonist (E(max.) 75%, EC(50) 3.5 nM). JB-788 did not exhibit any D(2) receptor agonism but progressively inhibited the effects of quinpirole, a D(2) receptor agonist, in the cAMP accumulation test with a K(i) value of 250 nM. JB-788 induced a weak change in cAMP levels in mouse brain but, like some antipsychotics, transiently increased glycogen contents in various brain regions. Behavioral effects were investigated in mice using the elevated plus-maze. JB-788 was found to increase the time duration spent by animals in anxiogenic situations. Locomotor hyperactivity induced by methamphetamine in mouse, a model of antipsychotic activity, was dose-dependently inhibited by JB-788. Altogether, these results suggest that JB-788 displays pharmacological properties, which could be of interest in the area

  4. In vivo labeling of 5-hydroxytryptamine uptake sites in mouse brain with ( sup 3 H)-6-nitroquipazine

    SciTech Connect

    Hashimoto, K.; Goromaru, T. )

    1990-10-01

    6-Nitroquipazine (DU 24565; 6-nitro 2-piperazinylquinoline) is a very potent 5-hydroxytryptamine (5-HT; serotonin) uptake inhibitor. It has been demonstrated very recently that (3H)-6-nitroquipazine is a suitable radioligand for studying 5-HT uptake sites. The present study evaluates (3H)6-nitroquipazine as a radioligand for in vivo labeling of 5-HT uptake sites in mouse brain. Very high uptake of radioactivity in the brain after i.v. administration of (3H)-6-nitroquipazine was shown. Regional distribution of the radioactivity in mouse brain 3 hr after injection of (3H)-6-nitroquipazine was in the order (highest to lowest) hypothalamus greater than midbrain greater than striatum greater than hippocampus greater than cerebral cortex greater than medulla oblongata greater than cerebellum. The regional distribution of in vivo (3H)-6-nitroquipazine binding in mouse brain was highly correlated with that in rat brain obtained from previous in vitro binding studies. Coadministration of carrier 6-nitroquipazine (5 mg/kg) significantly decreased the radioactivity in the hypothalamus, whereas that in the cerebellum and cerebral cortex was increased. Because the cerebellum has very low density of (3H)-6-nitroquipazine binding sites, the radioactivity in the cerebellum could, therefore, reflect the amount on nonspecific binding and free ligand. Kinetic studies showed highest in vivo specific binding 1 hr after injection of (3H)-6-nitroquipazine and slow clearance of specific binding. Specific binding in the hypothalamus was inhibited in a stereoselective manner by the stereoisomers of norzimelidine. Furthermore, specific binding in the hypothalamus was reduced by several 5-HT uptake inhibitors, in a dose-dependent manner.

  5. Proton Pump Inhibitors Inhibit Metformin Uptake by Organic Cation Transporters (OCTs)

    PubMed Central

    Nies, Anne T.; Hofmann, Ute; Resch, Claudia; Schaeffeler, Elke; Rius, Maria; Schwab, Matthias

    2011-01-01

    Metformin, an oral insulin-sensitizing drug, is actively transported into cells by organic cation transporters (OCT) 1, 2, and 3 (encoded by SLC22A1, SLC22A2, or SLC22A3), which are tissue specifically expressed at significant levels in various organs such as liver, muscle, and kidney. Because metformin does not undergo hepatic metabolism, drug-drug interaction by inhibition of OCT transporters may be important. So far, comprehensive data on the interaction of proton pump inhibitors (PPIs) with OCTs are missing although PPIs are frequently used in metformin-treated patients. Using in silico modeling and computational analyses, we derived pharmacophore models indicating that PPIs (i.e. omeprazole, pantoprazole, lansoprazole, rabeprazole, and tenatoprazole) are potent OCT inhibitors. We then established stably transfected cell lines expressing the human uptake transporters OCT1, OCT2, or OCT3 and tested whether these PPIs inhibit OCT-mediated metformin uptake in vitro. All tested PPIs significantly inhibited metformin uptake by OCT1, OCT2, and OCT3 in a concentration-dependent manner. Half-maximal inhibitory concentration values (IC50) were in the low micromolar range (3–36 µM) and thereby in the range of IC50 values of other potent OCT drug inhibitors. Finally, we tested whether the PPIs are also transported by OCTs, but did not identify PPIs as OCT substrates. In conclusion, PPIs are potent inhibitors of the OCT-mediated metformin transport in vitro. Further studies are needed to elucidate the clinical relevance of this drug-drug interaction with potential consequences on metformin disposition and/or efficacy. PMID:21779389

  6. An electrophysiological investigation of the properties of 5-HT3 receptors of rabbit nodose ganglion neurones in culture.

    PubMed Central

    Peters, J. A.; Malone, H. M.; Lambert, J. J.

    1993-01-01

    1. The biophysical and pharmacological properties of 5-hydroxytryptamine (5-HT)-evoked currents in rabbit nodose ganglion neurones in culture have been determined by use of the whole-cell and outside-out membrane patch recording modes of the patch-clamp technique. 2. In 49% of cells investigated the bath application of 10(-5) M 5-HT at negative holding potentials elicited an inward current. The whole-cell response to 5-HT reversed in sign (E5-HT) at approximately -2 mV and exhibited inward rectification. 3. The influence of various ion substitutions upon E5-HT established that the 5-HT-evoked current is mainly mediated by a mixed Na+, K+ cation conductance with little or no contribution from Cl- ions. The omission of Ca2+ and Mg2+ from the extracellular solution enhanced the amplitude of the 5-HT-induced current. 4. On isolated outside-out membrane patches, the bath application of 10(-6) M 5-HT induced single channel currents with a chord conductance of approximately 17 pS at -70 mV and an average slope conductance of 19 pS over the range -100 to -40 mV. The 5-HT-induced single channels exhibited modest inward rectification and were reduced in frequency, but not amplitude, by the 5-HT3 receptor antagonist metoclopramide (10(-6) M). 5. The bath application of 5-HT (3 x 10(-7)-3 x 10(-5) M) to whole cells voltage clamped at -60 mV produced dose-dependent inward currents which were mimicked by 2-methyl-5-HT and 1-phenylbiguanide with equipotent molar ratios, relative to 5-HT, of 2.5 and 32 respectively. 6. Whole-cell inward currents produced by the local pressure application of 5-HT (10(-5) M) were unaffected by 10(-6) M methysergide, 10(-6) M ketanserin or 10(-6) M citalopram, but were concentration-dependently antagonized by the selective 5-HT3 receptor antagonists tropisetron (IC50 = 4.6 x 10(-11) M) ondansetron (IC50 = 5.7 x 10(-11) M), and bemesetron (IC50 = 3.3 x 10(-10) M). The response to 5-HT was also blocked by the non-selective antagonists metoclopramide

  7. Serotonin directly stimulates luteinizing hormone-releasing hormone release from GT1 cells via 5-HT7 receptors.

    PubMed

    Héry, M; François-Bellan, A M; Héry, F; Deprez, P; Becquet, D

    1997-10-01

    Luteinizing hormone-releasing hormone (LHRH release, which serves as the primary drive to the hypothalamic-pituitary gonadal axis, is controlled by many neuromediators. Serotonin has been implicated in this regulation. However, it is unclear whether the central effect of serotonin on LHRH secretion is exerted directly on LHRH neurosecretory neurons or indirectly via multisynaptic pathways. The present studies were undertaken in order to examine whether LHRH secretion from immortalized LHRH cell lines is directly regulated by serotonin and, if so, to identify the receptor subtype involved. 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a 5-HT1A/7 receptor agonist, stimulated LHRH release from GT1-1 cells. This effect was blocked by ritanserin, a 5-HT2/7 receptor antagonist, but not by SDZ-216-525, a 5-HT1A antagonist. Basal LHRH release was not affected by the 5-HT2 agonist DOI. Reverse transcription and polymerase chain reaction technique (RT-PCR) was used in order to identify 5-HT1A and 5-HT7 receptor mRNA in immortalized LHRH cell lines. GT1-1 cells express mRNA for the 5-HT7, but not the 5-HT1A receptor subtypes. These results demonstrate a direct stimulatory effect of serotonin on LHRH release via 5-HT7 receptor.

  8. 5-HT3 receptor-channels coupled with Na+ influx in human T cells: role in T cell activation.

    PubMed

    Khan, N A; Poisson, J P

    1999-09-01

    The study was conducted on a human (Jurkat) T cell line, loaded with a Na+ fluorescent probe, SBFI/AM. Serotonin and an agonist of 5-HT3 receptor-channels, 2-methyl-5HT, evoked Na+ influx, whereas the agonists of other serotonergic receptor subtypes, i.e., 5-HT1A and 5-HT1B receptors, failed to induce Na+ influx in these cells. By using 3H-BRL43694, an agonist of 5-HT3 receptor-channels, we characterized 5-HT3 lymphocyte receptors which exhibited a density (Bmax) of 300 +/- 20 fmol/10(6) cells and a Kd of 30 nM in Jurkat T cells. The T-cell 5-HT3 receptor-channel is not regulated either by the protein kinase C or by the free intracellular calcium concentrations as the agents known to activate the PKC and to induce increases in intracellular free calcium concentrations failed to influence the free intracellular Na+ concentrations, [Na+]i, in these cells. Furthermore, an increase in [Na+]i, induced by 2-methyl-5HT, via 5-HT3 receptor-channels seems to stimulate T-cell activation by facilitating the progression of T cells from S to G2/M phase of the cell cycle.

  9. Descending Control of Itch Transmission by the Serotonergic System via 5-HT1A-Facilitated GRP-GRPR Signaling

    PubMed Central

    Zhao, Zhong-Qiu; Liu, Xian-Yu; Jeffry, Joseph; Karunarathne, W.K. Ajith; Li, Jin-Lian; Munanairi, Admire; Zhou, Xuan-Yi; Li, Hui; Sun, Yan-Gang; Wan, Li; Wu, Zhen-Yu; Kim, Seungil; Huo, Fu-Quan; Mo, Ping; Barry, Devin M; Zhang, Chun-Kui; Kim, Ji-Young; Gautam, N.; Renner, Kenneth J.; Li, Yun-Qing; Chen, Zhou-Feng

    2014-01-01

    SUMMARY Central serotonin (5-HT) modulates somatosensory transduction, but how it achieves sensory modality-specific modulation remains unclear. Here we report that enhancing serotonergic tone via administration of 5-hydroxytryptophan potentiates itch sensation, whereas mice lacking 5-HT or serotonergic neurons in the brainstem exhibit markedly reduced scratching behavior. Through pharmacological and behavioral screening, we identified 5-HT1A as a key receptor in facilitating gastrin-releasing peptide (GRP)-dependent scratching behavior. Co-activation of 5-HT1A and GRP receptors (GRPR) greatly potentiates subthreshold, GRP-induced Ca2+ transients and action potential firing of GRPR+ neurons. Immunostaining, biochemical and biophysical studies suggest that 5-HT1A and GRPR may function as receptor heteromeric complexes. Furthermore, 5-HT1A blockade significantly attenuates, whereas its activation contributes to, long-lasting itch transmission. Thus, our studies demonstrate that the descending 5-HT system facilitates GRP-GRPR signaling via 5-HT1A to augment itch-specific outputs and a disruption of crosstalk between 5-HT1A and GRPR may be a useful anti-pruritic strategy. PMID:25453842

  10. 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.

  11. Amisulpride is a potent 5-HT7 antagonist: relevance for antidepressant actions in vivo

    PubMed Central

    Abbas, Atheir I.; Hedlund, Peter B.; Huang, Xi-Ping; Tran, Thuy B.; Meltzer, Herbert Y.; Roth, Bryan L.

    2010-01-01

    Rationale Amisulpride is approved for clinical use in treating schizophrenia in a number of European countries and also for treating dysthymia, a mild form of depression, in Italy. Amisulpride has also been demonstrated to be an antidepressant for patients with major depression in many clinical trials. In part because of the selective D2/D3 receptor antagonist properties of amisulpride, it has long been widely assumed that dopaminergic modulation is the proximal event responsible for mediating its antidepressant and antipsychotic properties. Objectives The purpose of these studies was to determine if amisulpride’s antidepressant actions are mediated by off-target interactions with other receptors. Materials and Methods We performed experiments that: (1) examined the pharmacological profile of amisulpride at a large number of CNS molecular targets and (2) after finding high potency antagonist affinity for human 5-HT7a serotonin receptors, characterized the actions of amisulpride as an antidepressant in wild-type and 5-HT7 receptor knock-out mice. Results We discovered that amisulpride was a potent competitive antagonist at 5-HT7a receptors and that interactions with no other molecular target investigated here could explain its antidepressant actions in vivo. Significantly, and in contrast to their wildtype littermates, 5-HT7 receptor knockout mice did not respond to amisulpride in a widely used rodent model of depression, the tail suspension test. Conclusions These results indicate that 5-HT7a receptor antagonism, and not D2/D3 receptor antagonism, likely underlies the antidepressant actions of amisulpride. PMID:19337725

  12. Serotonin (5-HT3) receptor antagonists for the reduction of symptoms of low anterior resection syndrome

    PubMed Central

    Itagaki, Ryohei; Koda, Keiji; Yamazaki, Masato; Shuto, Kiyohiko; Kosugi, Chihiro; Hirano, Atsushi; Arimitsu, Hidehito; Shiragami, Risa; Yoshimura, Yukino; Suzuki, Masato

    2014-01-01

    Purpose Serotonin (5-hydroxytryptamine [5-HT])3 receptor antagonists are effective for the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D), in which exaggerated intestinal/colonic hypermotility is often observed. Recent studies have suggested that the motility disorder, especially spastic hypermotility, seen in the neorectum following sphincter-preserving operations for rectal cancer may be the basis of the postoperative defecatory malfunction seen in these patients. We investigated the efficacy of 5-HT3 receptor antagonists in patients suffering from severe low anterior resection syndrome. Patients and methods A total of 25 male patients with complaints of uncontrollable urgency or fecal incontinence following sphincter-preserving operations were enrolled in this study. Defecatory status, assessed on the basis of incontinence score (0–20), urgency grade (0–3), and number of toilet visits per day, was evaluated using a questionnaire before and 1 month after the administration of the 5-HT3 antagonist ramosetron. Results All the parameters assessed improved significantly after taking ramosetron for 1 month. The effect was more prominent in cases whose anastomotic line was lower, ie, inside the anal canal. Defecatory function was better in patients who commenced ramosetron therapy within 6 months postoperatively, as compared to those who were not prescribed ramosetron for more than 7 months postoperatively. Conclusion These results suggest that 5-HT3 antagonists are effective for the treatment of low anterior resection syndrome, as in diarrhea-predominant irritable bowel syndrome. The improvement in symptoms is not merely time dependent, but it is related to treatment with 5-HT3 antagonists. PMID:24648748

  13. Activation of 5-HT3 receptors leads to altered responses 6 months after MDMA treatment.

    PubMed

    Gyongyosi, Norbert; Balogh, Brigitta; Katai, Zita; Molnar, Eszter; Laufer, Rudolf; Tekes, Kornelia; Bagdy, Gyorgy

    2010-03-01

    The recreational drug "Ecstasy" [3,4-methylenedioxymethamphetamine (MDMA)] has a well-characterised neurotoxic effect on the 5-hydroxytryptamine (5-HT) neurons in animals. Despite intensive studies, the long-term functional consequencies of the 5-HT neurodegeneration remains elusive. The aim of this study was to investigate whether any alteration of 5-hydroxytryptamine-3 (5-HT(3)) receptor functions on the sleep-wake cycle, motor activity, and quantitative EEG could be detected 6 months after a single dose of 15 mg/kg of MDMA. The selective 5-HT(3) receptor agonist m-chlorophenylbiguanide (mCPBG; 1 mg/kg, i.p.) or vehicle was administered to freely moving rats pre-treated with MDMA (15 mg/kg, i.p.) or vehicle 6 months earlier. Polysomnographic and motor activity recordings were performed. Active wake (AW), passive wake (PW), light slow wave sleep (SWS-1), deep slow wave sleep (SWS-2), and paradoxical sleep were classified. In addition, EEG power spectra were calculated for the second hour after mCPBG treatment for each stage. AW increased and SWS-1 decreased in the second hour after mCPBG treatment in control animals. mCPBG caused significant changes in the EEG power in states with cortical activation (AW, PW, paradoxical sleep). In addition, mCPBG had a biphasic effect on hippocampal theta power in AW with a decrease in 7 Hz and a stage-selective increase in the upper range (8-9 Hz). Effects of mCPBG on the time spent in AW and SWS-1 were eliminated or reduced in MDMA-treated animals. In addition, mCPBG did not increase the upper theta power of AW in rats pre-treated with MDMA. These data suggest long-term changes in 5-HT(3) receptor function after MDMA. PMID:20052506

  14. Alterations of cognitive function and 5-HT system in rats after long term microwave exposure.

    PubMed

    Li, Hai-Juan; Peng, Rui-Yun; Wang, Chang-Zhen; Qiao, Si-Mo; Yong, Zou; Gao, Ya-Bing; Xu, Xin-Ping; Wang, Shao-Xia; Dong, Ji; Zuo, Hong-Yan; Li, Zhao; Zhou, Hong-Mei; Wang, Li-Feng; Hu, Xiang-Jun

    2015-03-01

    The increased use of microwaves raises concerns about its impact on health including cognitive function in which neurotransmitter system plays an important role. In this study, we focused on the serotonin system and evaluated the long term effects of chronic microwave radiation on cognition and correlated items. Wistar rats were exposed or sham exposed to 2.856GHz microwaves with the average power density of 5, 10, 20 or 30mW/cm(2) respectively for 6min three times a week up to 6weeks. At different time points after the last exposure, spatial learning and memory function, morphology structure of the hippocampus, electroencephalogram (EEG) and neurotransmitter content (amino acid and monoamine) of rats were tested. Above results raised our interest in serotonin system. Tryptophan hydroxylase 1 (TPH1) and monoamine oxidase (MAO), two important rate-limiting enzymes in serotonin synthesis and metabolic process respectively, were detected. Expressions of serotonin receptors including 5-HT1A, 2A, 2C receptors were measured. We demonstrated that chronic exposure to microwave (2.856GHz, with the average power density of 5, 10, 20 and 30mW/cm(2)) could induce dose-dependent deficit of spatial learning and memory in rats accompanied with inhibition of brain electrical activity, the degeneration of hippocampus neurons, and the disturbance of neurotransmitters, among which the increase of 5-HT occurred as the main long-term change that the decrease of its metabolism partly contributed to. Besides, the variations of 5-HT1AR and 5-HT2CR expressions were also indicated. The results suggested that in the long-term way, chronic microwave exposure could induce cognitive deficit and 5-HT system may be involved in it.

  15. Long-Term Citalopram Treatment Alters the Stress Responses of the Cortical Dopamine and Noradrenaline Systems: the Role of Cortical 5-HT1A Receptors

    PubMed Central

    Kaneko, Fumi; Kishikawa, Yuki; Hanada, Yuuki; Yamada, Makiko; Kakuma, Tatsuyuki; Kawahara, Hiroshi; Nishi, Akinori

    2016-01-01

    Background: Cortical dopamine and noradrenaline are involved in the stress response. Citalopram, a selective serotonin reuptake inhibitor, has direct and indirect effects on the serotonergic system. Furthermore, long-term treatment with citalopram affects the dopamine and noradrenaline systems, which could contribute to the therapeutic action of antidepressants. Methods: The effects of long-term treatment with citalopram on the responses of the dopamine and noradrenaline systems in the rat prefrontal cortex to acute handling stress were evaluated using in vivo microdialysis. Results: Acute handling stress increased dopamine and noradrenaline levels in the prefrontal cortex. The dopamine and noradrenaline responses were suppressed by local infusion of a 5-HT1A receptor agonist, 7-(Dipropylamino)-5,6,7,8-tetrahydronaphthalen-1-ol;hydrobromide, into the prefrontal cortex. The dopamine response was abolished by long-term treatment with citalopram, and the abolished dopamine response was reversed by local infusion of a 5-HT1A receptor antagonist, (Z)-but-2-enedioic acid;N-[2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-pyridin-2-ylcyclohexanecarboxamide into the prefrontal cortex. On the other hand, long-term treatment with citalopram reduced the basal noradrenaline levels (approximately 40% of the controls), but not the basal dopamine levels. The noradrenaline response was maintained despite the low basal noradrenaline levels. Signaling from the 5-HT1A receptors and α2-adrenoceptors was not involved in the decrease in the basal noradrenaline levels but partially affected the noradrenaline response. Conclusions: Chronic citalopram treatment differentially suppresses the dopamine and noradrenaline systems in the prefrontal cortex, and the dopamine stress response was preferentially controlled by upregulating 5-HT1A receptor signaling. Our findings provide insight into how antidepressants modulate the dopamine and noradrenaline systems to overcome acute stress. PMID

  16. Cannabidiol attenuates catalepsy induced by distinct pharmacological mechanisms via 5-HT1A receptor activation in mice.

    PubMed

    Gomes, Felipe V; Del Bel, Elaine A; Guimarães, Francisco S

    2013-10-01

    Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa plant that produces antipsychotic effects in rodents and humans. It also reverses L-dopa-induced psychotic symptoms and improves motor function in Parkinson's patients. This latter effect raised the possibility that CBD could have beneficial effects on motor related striatal disorders. To investigate this possibility we evaluated if CBD would prevent catalepsy induced by drugs with distinct pharmacological mechanisms. The catalepsy test is largely used to investigate impairments of motor function caused by interference on striatal function. Male Swiss mice received acute pretreatment with CBD (5, 15, 30 or 60mg/kg, ip) 30min prior to the D2 receptor antagonist haloperidol (0.6mg/kg), the non-selective nitric oxide synthase (NOS) inhibitor L-nitro-N-arginine (L-NOARG, 80mg/kg) or the CB1 receptor agonist WIN55,212-2 (5mg/kg). The mice were tested 1, 2 or 4h after haloperidol, L-NOARG or WIN55,212-2 injection. These drugs significantly increased catalepsy time and this effect was attenuated dose-dependently by CBD. CBD, by itself, did not induce catalepsy. In a second set of experiments the mechanism of CBD effects was investigated. Thirty minutes before CBD (30mg/kg) the animals received the 5-HT1A receptor antagonist WAY100635 (0.1mg/kg). The anticataleptic effect of CBD was prevented by WAY100635. These findings indicate that CBD can attenuate catalepsy caused by different mechanisms (D2 blockade, NOS inhibition and CB1 agonism) via 5-HT1A receptor activation, suggesting that it could be useful in the treatment of striatal disorders.

  17. Modulatory effect of the 5-HT1A agonist buspirone and the mixed non-hallucinogenic 5-HT1A/2A agonist ergotamine on psilocybin-induced psychedelic experience.

    PubMed

    Pokorny, Thomas; Preller, Katrin H; Kraehenmann, Rainer; Vollenweider, Franz X

    2016-04-01

    The mixed serotonin (5-HT) 1A/2A/2B/2C/6/7 receptor agonist psilocybin dose-dependently induces an altered state of consciousness (ASC) that is characterized by changes in sensory perception, mood, thought, and the sense of self. The psychological effects of psilocybin are primarily mediated by 5-HT2A receptor activation. However, accumulating evidence suggests that 5-HT1A or an interaction between 5-HT1A and 5-HT2A receptors may contribute to the overall effects of psilocybin. Therefore, we used a double-blind, counterbalanced, within-subject design to investigate the modulatory effects of the partial 5-HT1A agonist buspirone (20mg p.o.) and the non-hallucinogenic 5-HT2A/1A agonist ergotamine (3mg p.o.) on psilocybin-induced (170 µg/kg p.o.) psychological effects in two groups (n=19, n=17) of healthy human subjects. Psychological effects were assessed using the Altered State of Consciousness (5D-ASC) rating scale. Buspirone significantly reduced the 5D-ASC main scale score for Visionary Restructuralization (VR) (p<0.001), which was mostly driven by a reduction of the VR item cluster scores for elementary and complex visual hallucinations. Further, buspirone also reduced the main scale score for Oceanic Boundlessness (OB) including derealisation and depersonalisation phenomena at a trend level (p=0.062), whereas ergotamine did not show any effects on the psilocybin-induced 5D-ASC main scale scores. The present finding demonstrates that buspirone exerts inhibitory effects on psilocybin-induced effects, presumably via 5-HT1A receptor activation, an interaction between 5-HT1A and 5-HT2A receptors, or both. The data suggest that the modulation of 5-HT1A receptor activity may be a useful target in the treatment of visual hallucinations in different psychiatric and neurological diseases. PMID:26875114

  18. Modulatory effect of the 5-HT1A agonist buspirone and the mixed non-hallucinogenic 5-HT1A/2A agonist ergotamine on psilocybin-induced psychedelic experience.

    PubMed

    Pokorny, Thomas; Preller, Katrin H; Kraehenmann, Rainer; Vollenweider, Franz X

    2016-04-01

    The mixed serotonin (5-HT) 1A/2A/2B/2C/6/7 receptor agonist psilocybin dose-dependently induces an altered state of consciousness (ASC) that is characterized by changes in sensory perception, mood, thought, and the sense of self. The psychological effects of psilocybin are primarily mediated by 5-HT2A receptor activation. However, accumulating evidence suggests that 5-HT1A or an interaction between 5-HT1A and 5-HT2A receptors may contribute to the overall effects of psilocybin. Therefore, we used a double-blind, counterbalanced, within-subject design to investigate the modulatory effects of the partial 5-HT1A agonist buspirone (20mg p.o.) and the non-hallucinogenic 5-HT2A/1A agonist ergotamine (3mg p.o.) on psilocybin-induced (170 µg/kg p.o.) psychological effects in two groups (n=19, n=17) of healthy human subjects. Psychological effects were assessed using the Altered State of Consciousness (5D-ASC) rating scale. Buspirone significantly reduced the 5D-ASC main scale score for Visionary Restructuralization (VR) (p<0.001), which was mostly driven by a reduction of the VR item cluster scores for elementary and complex visual hallucinations. Further, buspirone also reduced the main scale score for Oceanic Boundlessness (OB) including derealisation and depersonalisation phenomena at a trend level (p=0.062), whereas ergotamine did not show any effects on the psilocybin-induced 5D-ASC main scale scores. The present finding demonstrates that buspirone exerts inhibitory effects on psilocybin-induced effects, presumably via 5-HT1A receptor activation, an interaction between 5-HT1A and 5-HT2A receptors, or both. The data suggest that the modulation of 5-HT1A receptor activity may be a useful target in the treatment of visual hallucinations in different psychiatric and neurological diseases.

  19. Use of inhibitors for coastal bacteria and phytoplankton: Application to nitrogen uptake measurement

    NASA Astrophysics Data System (ADS)

    Trottet, Aurore; Fouilland, Eric; Leboulanger, Christophe; Lanouguère, Elodie; Bouvy, Marc

    2011-06-01

    For several decades, prokaryotic and eukaryotic inhibitors have been used to exclude bacteria from microalgal cultures and for investigating prey-predator relationships. Recently there has been considerable interest in using specific inhibitors for studying the interactions between bacteria and phytoplankton, by selective repression of either organism's activity. The effectiveness of chemical inhibitors must be tested before applying them to natural communities to partition metabolic activities between functional groups. Six different antibiotics selected from the most commonly reported in the literature were tested, at concentrations varying from 12.5 to 100 mg L -1, for their effect on bacterial growth and functional diversity of natural communities from Mediterranean coastal waters. Penicillin and streptomycin each at a final concentration of 100 mg L -1 significantly reduced bacterial growth within 2 h. There was a greater impact on bacterial functional diversity when both antibiotics were mixed together. This mixture did not have any significant effect on the growth of selected cultured phytoplankton strains, whereas the eukaryote inhibitor cycloheximide at 100 mg L -1 reduced growth within 2 h of incubation. The penicillin-streptomycin mixture and cycloheximide alone successfully partitioned NH 4+ and NO 3- uptake between bacteria and phytoplankton bi-weekly sampled in a coastal lagoon in Autumn, where bacterial contribution to total NH 4+ and NO 3- uptake averaged 46 and 41%, respectively. The use of specific inhibitors may be a valuable method for studying interactions, such as competition and mutualism, or lack of interaction between the different components of microbial communities and could be used to study their relative importance in biogeochemical fluxes.

  20. An Algorithm to Identify Target-Selective Ligands – A Case Study of 5-HT7/5-HT1A Receptor Selectivity

    PubMed Central

    Kurczab, Rafał; Canale, Vittorio; Zajdel, Paweł; Bojarski, Andrzej J.

    2016-01-01

    A computational procedure to search for selective ligands for structurally related protein targets was developed and verified for serotonergic 5-HT7/5-HT1A receptor ligands. Starting from a set of compounds with annotated activity at both targets (grouped into four classes according to their activity: selective toward each target, not-selective and not-selective but active) and with an additional set of decoys (prepared using DUD methodology), the SVM (Support Vector Machines) models were constructed using a selective subset as positive examples and four remaining classes as negative training examples. Based on these four component models, the consensus classifier was then constructed using a data fusion approach. The combination of two approaches of data representation (molecular fingerprints vs. structural interaction fingerprints), different training set sizes and selection of the best SVM component models for consensus model generation, were evaluated to determine the optimal settings for the developed algorithm. The results showed that consensus models with molecular fingerprints, a larger training set and the selection of component models based on MCC maximization provided the best predictive performance. PMID:27271158

  1. Akt inhibitors reduce glucose uptake independently of their effects on Akt.

    PubMed

    Tan, Shi-Xiong; Ng, Yvonne; James, David E

    2010-11-15

    The protein kinase Akt is involved in various cellular processes, including cell proliferation, growth and metabolism. Hyperactivation of Akt is commonly observed in human tumours and so this pathway has been the focus of targeted drug discovery. However, Akt also plays an essential role in other physiological processes, such as the insulin-regulated transport of glucose into muscle and fat cells. This process, which is essential for whole-body glucose homoeostasis in mammals, is thought to be mediated via Akt-dependent movement of GLUT4 glucose transporters to the plasma membrane. In the present study, we have investigated the metabolic side effects of non-ATP-competitive allosteric Akt inhibitors. In 3T3-L1 adipocytes, these inhibitors caused a decrease in the Akt signalling pathway concomitant with reduced glucose uptake. Surprisingly, a similar reduction in GLUT4 translocation to the plasma membrane was not observed. Further investigation revealed that the inhibitory effects of these compounds on glucose uptake in 3T3-L1 adipocytes were independent of the Akt signalling pathway. The inhibitors also inhibited glucose transport into other cell types, including human erythrocytes and T-47D breast cancer cells, suggesting that these effects are not specific to GLUT4. We conclude that these drugs may, at least in part, inhibit tumorigenesis through inhibition of tumour cell glucose transport.

  2. Effects of maturation, artery size, and chronic hypoxia on 5-HT receptor type in ovine cranial arteries.

    PubMed

    Teng, G Q; Williams, J; Zhang, L; Purdy, R; Pearce, W J

    1998-09-01

    To test the hypothesis that variations in cerebrovascular reactivity to 5-HT among arteries of different size or type, during maturation, or during acclimatization to high altitude involve differences in serotonergic receptor subtype, we determined relative agonist potency orders and antagonist affinities in common carotid (Com), main branch middle cerebral (Main), and second branch middle cerebral (2BR) arteries from term fetal lambs and nonpregnant adult sheep acclimatized at sea level or at an altitude of 3,820 m for approximately 110 days. In normoxic adult Com segments, agonist potency order was 5-hydroxytryptamine (5-HT) > 5-carboxamidotryptamine (5-CT) >/= 8-hydroxy-2(di-n-propylamino)tetraline (8-OH-DPAT); sumatriptan (Suma) produced no contractile response; and antagonist dissociation constant (pKb) values were 9.4 and 9.5 for ketanserin against 5-HT and 5-CT, 7.5 for GR-127935 against 5-HT, and 7.2 for SB-206553 against 5-HT. In normoxic adult Main segments, agonist potency order was 5-HT > 5-CT >/= Suma >/= DPAT, and pKb values were 9.1 and 9.2 for ketanserin against 5-HT and 5-CT and 7.4 and 8.5 for GR-127935 against 5-HT and Suma, respectively. In the 2BR segments from normoxic adults, agonist potency order was 5-CT > 5-HT > Suma > DPAT and pKb values were 7.4 and 7.2 for ketanserin against 5-HT and 5-CT and 10.0 and 8.7 for GR-127935 against 5-HT and Suma, respectively. Compared with normoxic adults, none of these values were significantly different in hypoxic adults and in fetuses only the pKb values for ketanserin against 5-HT in the 2BR segments (8.8) were greater. From these results we propose that the ratio of 5-HT2 to 5-HT1 receptors is greatest in the Com and decreases progressively to its smallest values in 2BR or smaller segments. Because this gradient appears stable and relatively resistant to the effects of maturation and chronic hypoxia, changes in reactivity associated with these perturbations may involve alterations in receptor density

  3. An interplay between the serotonin transporter (SERT) and 5-HT receptors controls stimulus-secretion coupling in sympathoadrenal chromaffin cells.

    PubMed

    Brindley, Rebecca L; Bauer, Mary Beth; Blakely, Randy D; Currie, Kevin P M

    2016-11-01

    Adrenal chromaffin cells (ACCs), the neuroendocrine arm of the sympathetic nervous system, secrete catecholamines to mediate the physiological response to stress. Although ACCs do not synthesize 5-HT, they express the serotonin transporter (SERT). Genetic variations in SERT are linked to several CNS disorders but the role(s) of SERT/5-HT in ACCs has remained unclear. Adrenal glands from wild-type mice contained 5-HT at ≈ 750 fold lower abundance than adrenaline, and in SERT(-/-) mice this was reduced by ≈80% with no change in catecholamines. Carbon fibre amperometry showed that SERT modulated the ability of 5-HT1A receptors to inhibit exocytosis. 5-HT reduced the number of amperometric spikes (vesicular fusion events) evoked by KCl in SERT(-/-) cells and wild-type cells treated with escitalopram, a SERT antagonist. The 5-HT1A receptor antagonist WAY100635 blocked the inhibition by 5-HT which was mimicked by the 5-HT1A agonist 8-OH-DPAT but not the 5-HT1B agonist CP93129. There was no effect on voltage-gated Ca(2+) channels, K(+) channels, or intracellular [Ca(2+)] handling, showing the 5-HT receptors recruit an atypical inhibitory mechanism. Spike charge and kinetics were not altered by 5-HT receptors but were reduced in SERT(-/-) cells compared to wild-type cells. Our data reveal a novel role for SERT and suggest that adrenal chromaffin cells might be a previously unrecognized hub for serotonergic control of the sympathetic stress response. PMID:27544824

  4. 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.

  5. (+)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.

  6. Reviewing the serotonin reuptake inhibitors (SSRIs) footprint in the aquatic biota: uptake, bioaccumulation and ecotoxicology.

    PubMed

    Silva, Liliana J G; Pereira, André M P T; Meisel, Leonor M; Lino, Celeste M; Pena, Angelina

    2015-02-01

    Selective serotonin re-uptake inhibitors (SSRIs) antidepressants are amongst the most prescribed pharmaceutical active substances throughout the world. Their presence, already described in different environmental compartments such as wastewaters, surface, ground and drinking waters, and sediments, and their remarkable effects on non-target organisms justify the growing concern about these emerging environmental pollutants. A comprehensive review of the literature data with focus on their footprint in the aquatic biota, namely their uptake, bioaccumulation and both acute and chronic ecotoxicology is presented. Long-term multigenerational exposure studies, at environmental relevant concentrations and in mixtures of related compounds, such as oestrogenic endocrine disruptors, continue to be sparse and are imperative to better know their environmental impact.

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

    PubMed

    Bovetto, S; Rouillard, C; Richard, D

    1996-11-01

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

  8. Selective serotonin re-uptake inhibitors (SSRIs) in the aquatic environment: an ecopharmacovigilance approach.

    PubMed

    Silva, Liliana J G; Lino, Celeste M; Meisel, Leonor M; Pena, Angelina

    2012-10-15

    Selective serotonin re-uptake inhibitors (SSRIs) antidepressants are among the most prescribed pharmaceutical active substances throughout the world. The occurrence of these widely used compounds in different environmental compartments (wastewaters, surface, ground and drinking waters, and sediments), justify the growing concern about these emerging environmental pollutants. Viewing an ecopharmacovigilance approach, a comprehensive discussion of the state of the art regarding different contamination sources, fate, degradation and occurrence is presented. Information on the current distribution levels and fate in different environmental matrices continues to be sparse and measures are imperative to improve awareness and encourage precautionary actions to minimize SSRIs' environmental impact. PMID:22940043

  9. Serotonin uptake in blood platelets of psychiatric patients

    SciTech Connect

    Meltzer, H.Y.; Arora, R.C.; Baber, R.; Tricou, B.J.

    1981-12-01

    Platelet serotonin (5-HT) uptake was determined in 72 newly admitted, unmedicated psychiatric patients. Decreased maximum velocity (Vmax) of 5-HT uptake was present in unipolar and bipolar depressed patients as well as schizoaffective depressed patients. The apparent Michaelis constant (km) of 5-HT uptake was normal in these groups, as was Vmax and Km in manic-depressive and chronic schizophrenic patients. Treatment of depressed patients with notriptyline hydrochloride or imipramine hydrochloride increased Km significantly. There was a trend for the increase in Km in the nortriptyline-treated patients to correlate with clinical improvement. Decreased 5-HT uptake in platelets provides additional evidence for the role of 5-HT in the pathophysiologic process of some forms of depression.

  10. Role of "Aplysia" Cell Adhesion Molecules during 5-HT-Induced Long-Term Functional and Structural Changes

    ERIC Educational Resources Information Center

    Han, Jin-Hee; Lim, Chae-Seok; Lee, Yong-Seok; Kandel, Eric R.; Kaang, Bong-Kiun

    2004-01-01

    We previously reported that five repeated pulses of 5-HT lead to down-regulation of the TM-apCAM isoform at the surface of "Aplysia" sensory neurons (SNs). We here examined whether apCAM down-regulation is required for 5-HT-induced long-term facilitation. We also analyzed the role of the cytoplasmic and extracellular domains by overexpressing…

  11. Role of 5-hydroxytryptamine 1B (5-HT1B) receptors in the regulation of ethanol intake in rodents

    PubMed Central

    Sari, Youssef

    2012-01-01

    Evidence indicates that the serotonergic system is important in mediating dependence on and craving for alcohol. Among serotonin receptors, 5-hydroxytryptamine 1B (5-HT1B) receptors have been associated with drug abuse including alcohol. In this review, the neurocircuitry involving 5-HT1B receptors in central reward brain regions related to alcohol intake are discussed in detail. Emphasis has been placed on the pharmacological manipulations of 5-HT1B receptor-mediated alcohol intake. Furthermore, 5-HT1B auto- and hetero-receptors regulate alcohol intake through the regulatory mechanism involving release of 5-HT, gamma-aminobutyric acid (GABA), dopamine, and glutamate is evaluated. Thus, interactions between 5-HT1B receptors and these neurotransmitter systems are suggested to modulate alcohol-drinking behavior. This review on the role of 5-HT1B receptors in neurotransmitter release and consequent alcohol intake provides important information about the potential therapeutic role of 5-HT1B receptors for the treatment of alcohol dependence. PMID:23118018

  12. Functional evidence for the rapid desensitization of 5-HT(3) receptors on vagal afferents mediating the Bezold-Jarisch reflex

    NASA Technical Reports Server (NTRS)

    Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

    2000-01-01

    The aim of this study was to determine whether 5-hydroxytryptamine (5-HT)(3) receptors on cardiopulmonary afferents mediating the Bezold-Jarisch reflex (BJR) desensitize upon repeated exposure to selective agonists. BJR-mediated falls in heart rate, diastolic arterial blood pressure and cardiac output elicited by the 5-HT(3)-receptor agonists, phenylbiguanide (100 microg/kg, i.v.) or 2-methyl-5-HT (100 microg/kg, i.v.), progressively diminished upon repeated injection in conscious rats. The BJR responses elicited by 5-HT (40 microg/kg, i.v.) were markedly reduced in rats which had received the above injections of phenylbiguanide or 2-methyl-5-HT whereas the BJR responses elicited by L-S-nitrosocysteine (10 micromol/kg, i.v.) were similar before and after the injections of the 5-HT(3) receptor agonists. These findings suggest that tachyphylaxis to 5-HT(3) receptor agonists may be due to the desensitization of 5-HT(3) receptors on cardiopulmonary afferents rather than the impairment of the central or peripheral processing of the BJR.

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

    PubMed

    Benyamina, Amine; Naassila, Mickaël; Bourin, Michel

    2012-07-30

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

  14. Molecular characterization and analysis of a putative 5-HT receptor involved in reproduction process of the pearl oyster Pinctada fucata.

    PubMed

    Wang, Qi; He, Maoxian

    2014-08-01

    5-HT (5-hydroxytryptamine; serotonin) has been linked to a variety of biological roles including gonad maturation and sequential spawning in bivalve molluscs. To gain a better understanding of the effects of 5-HT on developmental regulation in the pearl oyster Pinctada fucata, the isolation, cloning, and expression of the 5-HT receptor was investigated in this study. A full-length cDNA (2541 bp) encoding a putative 5-HT receptor (5-HTpf) of 471 amino acids was isolated from the ovary of the pearl oyster. It shared 71% and 51% homology, respectively, with the Crassostrea gigas 5-HT receptor and the Aplysia californica 5-HT1ap. The 5-HTpf sequence possessed the typical characteristics of seven transmembrane domains and a long third inner loop. Phylogenetic analysis also indicated that 5-HTpf was classified into the 5-HT1 subtype together with other invertebrate 5-HT1 receptors. Quantitative RT-PCR showed that 5-HTpf is widely expressed in all tissues tested, is involved in the gametogenesis cycle, embryonic and larval development stages, and expression is induced by E2 in ovarian tissues. These results suggest that 5-HTpf is involved in the reproductive process, specifically in the induction of oocyte maturation and spawning of P. fucata.

  15. Neurochemical effects of buspirone in rat hippocampus: evidence for selective activation of 5HT neurons.

    PubMed

    Mennini, T; Gobbi, M; Ponzio, F; Garattini, S

    1986-01-01

    The effect of buspirone on neurotransmitter systems in rat hippocampus has been evaluated in vitro and in vivo. In vitro buspirone does not affect the specific binding of 3H-flunitrazepam, 3H-GABA, 3H-dexetimide, but displaces 3H-5HT binding with nanomolar affinity. Oral administration of buspirone does not modify the hippocampal concentrations of GABA, acetylcholine, choline and of 3H-flunitrazepam specifically bound in vivo, but results in a dose-dependent reduction of 5HIAA and noradrenaline concentrations. While the effect on noradrenaline is also obtained in striatum of buspirone-treated animals, the effect on 5HIAA shows a regional specificity. The in vitro and in vivo data suggest that buspirone specifically activates 5HT neurons in hippocampus, and are compared with those obtained with diazepam. PMID:2421657

  16. Anxiolytic actions of the substance P (NK1) receptor antagonist L-760735 and the 5-HT1A agonist 8-OH-DPAT in the social interaction test in gerbils.

    PubMed

    Cheeta, S; Tucci, S; Sandhu, J; Williams, A R; Rupniak, N M; File, S E

    2001-10-12

    The gerbil social interaction test has previously detected anxiolytic effects of nicotine and diazepam. In the present study, the high affinity substance P (NK(1)) receptor antagonist L-760735 (3 mg/kg) significantly increased the time spent in social interaction, whereas its low affinity analogue L-781773 (3 mg/kg) was without effect. Diazepam (0.1 mg/kg) and the 5-HT(1A) receptor agonist 8-OH-DPAT (0.003 and 0.01 mg/kg) also increased social interaction, whereas an acute dose of the selective serotonin re-uptake inhibitor fluoxetine (10 mg/kg) decreased the time spent in social interaction. Diazepam (0.1 mg/kg) significantly increased locomotor activity, but this effect was independent of the increase in social interaction. The other drugs tested were without effect on locomotor activity. The present findings suggest that the gerbil social interaction may well provide a useful assay for detecting both anxiolytic and anxiogenic compounds, and suggests that the high affinity NK(1) receptor antagonist L-760735 may prove to be useful as an anxiolytic therapy.

  17. 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

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

    PubMed

    Maksay, Gábor; Simonyi, Miklós; Bikádi, Zsolt

    2004-10-01

    The N-terminal extracellular regions of heterooligomeric 3AB-type human 5-hydroxytryptamine receptors (5-HT3ABR) were modelled based on the crystal structure of snail acetylcholine binding protein AChBP. Stepwise rotation of subunit A by 5 degrees was performed between -10 degrees and 15 degrees 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 degrees 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-pi 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 pi-cation-pi 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.

  19. Structure-Activity Relationships of Constrained Phenylethylamine Ligands for the Serotonin 5-HT2 Receptors

    PubMed Central

    Isberg, Vignir; Paine, James; Leth-Petersen, Sebastian; Kristensen, Jesper L.; Gloriam, David E.

    2013-01-01

    Serotonergic ligands have proven effective drugs in the treatment of migraine, pain, obesity, and a wide range of psychiatric and neurological disorders. There is a clinical need for more highly 5-HT2 receptor subtype-selective ligands and the most attention has been given to the phenethylamine class. Conformationally constrained phenethylamine analogs have demonstrated that for optimal activity the free lone pair electrons of the 2-oxygen must be oriented syn and the 5-oxygen lone pairs anti relative to the ethylamine moiety. Also the ethyl linker has been constrained providing information about the bioactive conformation of the amine functionality. However, combined 1,2-constriction by cyclization has only been tested with one compound. Here, we present three new 1,2-cyclized phenylethylamines, 9–11, and describe their synthetic routes. Ligand docking in the 5-HT2B crystal structure showed that the 1,2-heterocyclized compounds can be accommodated in the binding site. Conformational analysis showed that 11 can only bind in a higher-energy conformation, which would explain its absent or low affinity. The amine and 2-oxygen interactions with D3.32 and S3.36, respectively, can form but shift the placement of the core scaffold. The constraints in 9–11 resulted in docking poses with the 4-bromine in closer vicinity to 5.46, which is polar only in the human 5-HT2A subtype, for which 9–11 have the lowest affinity. The new ligands, conformational analysis and docking expand the structure-activity relationships of constrained phenethylamines and contributes towards the development of 5-HT2 receptor subtype-selective ligands. PMID:24244317

  20. Astrocytic 5-HT(2B) receptor as in vitro and in vivo target of SSRIs.

    PubMed

    Peng, Liang; Huang, Jingyang

    2012-12-01

    Most studies in this journal describe recent patents. The present study only has one such reference. Instead, we hope that its contents will trigger investigation of antidepressant drugs along the suggested lines and lead to ensuing patent applications - first and foremost by more focus on astrocytes. Clinical research has already pointed towards the importance of these cells, which account for one quarter of brain cortical volume and at least as much of its oxidative metabolism. Astrocytes express a multitude of receptors, including 5-HT(2B) receptors. In cultured astrocytes acute treatment with any of the five SSRIs, fluoxetine, fluvoxamine, sertraline, paroxetine, and citalopram, stimulates equipotently and with sufficient affinity to be therapeutically relevant, the 5-HT(2B) receptor. Following EGF receptor transactivation and a resultant autocrine HB-EGF stimulation, these drugs activate two interdependent signal pathways i) the Ras-Raf-Mek-ERK phosphorylation pathway and ii) the PI3K-AKT-GSK-3β pathway, eventually altering gene expression. Chronic treatment with fluoxetine upregulates gene expression of cPLA₂, ADAR2, GluK2 and 5-HT(2B) receptors, and RNA editing of the later two in cultured astrocytes and in astrocytes obtained by fluorescence-activated cell sorting of cells from fluoxetinetreated mice. Chronic treatment also down-regulates the Gq-protein-coupled receptor-induced increase of intracellular Ca²⁺ by inhibiting TRPC function, compromising astrocytic Ca²⁺ re-filling. This affects glycogenolysis and several steps in the signal pathways. Since astrocytes in the mature brain and in our cultures do not express SERT, both acute and chronic effects in cultured astrocytes must be directly mediated by 5-HT(2B) receptor activation. PMID:22963281

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

    PubMed

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

    2008-05-31

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

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

    PubMed

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

    2012-06-01

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

  3. Serotonin 5-HT7 receptors coupled to induction of interleukin-6 in human microglial MC-3 cells.

    PubMed

    Mahé, Cécile; Loetscher, Erika; Dev, Kumlesh K; Bobirnac, Ionel; Otten, Uwe; Schoeffter, Philippe

    2005-07-01

    Brain serotonin 5-HT(7) receptors are known to be expressed in neurons and astrocytes. We now report the presence of these receptors in a third type of cell, microglial cells. 5-Hydroxytryptamine (5-HT), 5-carboxamidotryptamine (5-CT), 5-methoxytryptamine (5-MeOT) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) induced concentration-dependent stimulations of cAMP accumulation in the human microglial MC-3 cell line. The maximal effect of 5-HT was 3.4+/-0.3-fold stimulation (mean+/-S.E.M., n=5) above basal levels. The rank order of agonist potency (pEC50 values) was 5-CT (7.09)>5-HT (6.13)>or=5-MeOT (5.78)>8-OH-DPAT (ca. 5). The effect of 5-CT was inhibited in a concentration-dependent manner by the selective 5-HT7 receptor antagonist SB-269970 (pA2 value 9.03). Western blot analysis revealed the presence of immunoreactive bands corresponding to the human 5-HT7 receptor in extracts of MC-3 cells. The presence of two splice variants of the 5-HT7 receptor (5-HT7(a/b)) was visualized by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis with specific primers. In real-time PCR studies, the mRNA for interleukin-6 (IL-6) was found to be increased by 2.5-fold in MC-3 cells after 1 h incubation with 5-CT (1 microM) and this effect was fully blocked by the 5-HT7 receptor antagonist SB-269970 (1 microM). These data show that functional 5-HT7 receptors are present in human microglial MC-3 cells, suggesting that they are involved in neuroinflammatory processes. PMID:15992579

  4. Decreased Incentive Motivation Following Knockout or Acute Blockade of the Serotonin Transporter: Role of the 5-HT2C Receptor.

    PubMed

    Browne, Caleb J; Fletcher, Paul J

    2016-09-01

    Acute pharmacological elevation of serotonin (5-hydroxytryptamine; 5-HT) activity decreases operant responding for primary reinforcers, suggesting that 5-HT reduces incentive motivation. The mechanism by which 5-HT alters incentive motivation is unknown, but parallel evidence that 5-HT2C receptor agonists also reduce responding for primary reinforcers implicates this receptor as a potential candidate. These experiments examined whether chronic and acute disruptions of serotonin transporter (SERT) activity altered incentive motivation, and whether the 5-HT2C receptor mediated the effects of elevated 5-HT on behavior. To assess incentive motivation, we measured responding for three different reinforcers: a primary reinforcer (saccharin), a conditioned reinforcer (CRf), and an unconditioned sensory reinforcer (USRf). In the chronic condition, responding was compared between SERT knockout (SERT-KO) mice and their wild-type littermates. In the acute condition, responding was examined in wild-type mice following treatment with 10 or 20 mg/kg citalopram, or its vehicle. The ability of the selective 5-HT2C antagonist SB 242084 to prevent the effects of SERT-KO and citalopram on responding was subsequently examined. Both SERT-KO and citalopram reduced responding for saccharin, a CRf, and a USRf. Treatment with SB 242084 enhanced responding for a CRf and a USRf in SERT-KO mice and blocked the effects of citalopram on CRf and USRf responding. However, SB 242084 was unable to prevent the effects of SERT-KO or citalopram on responding for saccharin. These results support a powerful inhibitory function for 5-HT in the control of incentive motivation, and indicate that the 5-HT2C receptor mediates these effects of 5-HT in a reinforcer-dependent manner. PMID:27125304

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

    PubMed

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

    2005-06-01

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

  6. Identification of 5HT/sub 2/-receptors on longitudinal muscle of the guinea pig ileum

    SciTech Connect

    Engel, G.; Hoyer, D.; Kalkman, H.O.; Wick, M.B.

    1984-01-01

    In binding experiments with the radioligands (/sup 3/H)Ketanserin (HKet) and (/sup 125/I)LSD (ILSD) 21 compounds were investigated using rat brain cortex membranes. The pK/sub D/-values of the compounds were virtually independent of the radioligand used and their rank order was consistent with classification of the binding sites as being of the 5-HT/sub 2/-type. In contrast, in the longitudinal muscle of the guinea pig ileum in the presence of 0.3 microM cinanserin, ILSD labelled sites which were quite different to those in the cortex. In a functional test antagonism of the 5HT induced contraction of the guinea-pig ileum was measured in the presence of 1 microM atropine. The pharmacological inhibition constants (IC/sub 50/-values) of 8 compounds correlated well with the dissociation constants for HKet binding in the cortex and did not correlate with the data from ILSD binding in the guinea pig ileum. It is concluded that the ileum contains postjunctional 5HT/sub 2/-receptors which mediate contraction. The nature of the ILSD binding sites in the ileum remains to be elucidated.

  7. Oleanolic acid acrylate elicits antidepressant-like effect mediated by 5-HT1A receptor.

    PubMed

    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 (E max = 26 ± 2.0%) on 5-HT1A receptor. In conclusion, our findings showed antidepressant-like effect of D1 and possible involvement of 5-HT1A receptor.

  8. Reward processing by the dorsal raphe nucleus: 5-HT and beyond

    PubMed Central

    Zhou, Jingfeng; Liu, Zhixiang

    2015-01-01

    The dorsal raphe nucleus (DRN) represents one of the most sensitive reward sites in the brain. However, the exact relationship between DRN neuronal activity and reward signaling has been elusive. In this review, we will summarize anatomical, pharmacological, optogenetics, and electrophysiological studies on the functions and circuit mechanisms of DRN neurons in reward processing. The DRN is commonly associated with serotonin (5-hydroxytryptamine; 5-HT), but this nucleus also contains neurons of the neurotransmitter phenotypes of glutamate, GABA and dopamine. Pharmacological studies indicate that 5-HT might be involved in modulating reward- or punishment-related behaviors. Recent optogenetic stimulations demonstrate that transient activation of DRN neurons produces strong reinforcement signals that are carried out primarily by glutamate. Moreover, activation of DRN 5-HT neurons enhances reward waiting. Electrophysiological recordings reveal that the activity of DRN neurons exhibits diverse behavioral correlates in reward-related tasks. Studies so far thus demonstrate the strong power of DRN neurons in reward signaling and at the same time invite additional efforts to dissect the roles and mechanisms of different DRN neuron types in various processes of reward-related behaviors. PMID:26286655

  9. Nerve growth induces 5-HT sub 3 recognition sites in rat pheochromocytoma (PC12) cells

    SciTech Connect

    Gordon, J.C.; Rowland, H.C. )

    1990-01-01

    In rat pheochromocytoma (PC12) cells, nerve growth factor (7S NGF) induced the expression of recognition sites that bind the specific 5-HT{sub 3} antagonist (S-) ({sup 3}H) zacopride. Culturing PC12 cells for 8-12 days in the presence of 50 ng/ml NGF increased the density (B{sub max}) of (S-) ({sup 3}H) zacopride binding sites in cell membranes (0-100,000 x g fraction) from 0 to 105 fmoles/mg protein. This binding exhibited high affinity for (S-) ({sup 3}H) zacopride (K{sub d}=0.8 nM), was specific (>95%), and was inhibited by 5-HT{sub 3} compounds with a rank of potency (quipazine>ICS 205-930 > GR38032F > BRL 24924{approx}MDL 72222 > phenylbiguanide {le} seroton-in > 2-methyl-serotonin > metoclopramide) which was distinct from neuroblastoma cells. Thus, NGF-differentiated PC12 cells possess a 5-HT{sub 3} receptor and should be useful to investigate its regulation and biochemical mechanism of action.

  10. Blocking 5-HT2 receptor restores cardiovascular disorders in type 1 experimental diabetes

    PubMed Central

    García-Pedraza, José-Ángel; Ferreira-Santos, Pedro; Aparicio, Rubén; Montero, María-José; Morán, Asunción

    2016-01-01

    This study aimed to determine whether the serotonergic modulation, through selective 5-HT2 receptor blockade, restores cardiovascular disturbances in type 1 diabetic rats. Diabetes was induced by alloxan (150 mg/kg, s.c.) and maintained for 4 weeks. 5-HT2 receptor was blocked by sarpogrelate (30 mg/kg.day; 14 days; p.o.). Systolic blood pressure (SBP), heart rate (HR), glycaemia and body weight (BW) were monitored periodically. Animals were sacrificed at the end of the study and the heart, right kidney and thoracic aorta were removed; plasma samples were also obtained. Left ventricular hypertrophy index (LVH) and renal hypertrophy index (RH) were determined. Vascular function was studied in aorta rings; additionally, superoxide anion (O2•−) production (by lucigenin-enhanced chemiluminescence) and lipid peroxidation (by thiobarbituric acid reactive substances assay) were measured. Neither alloxan nor sarpogrelate treatments altered HR, LVH or endothelium-independent relaxation. SBP, glycaemia, BW, RH, O2•− production and lipid peroxidation were significantly altered in diabetic animals compared with controls. Sarpogrelate treatment considerably decreased SBP, RH, O2•− production and lipid peroxidation. Endothelium-dependent relaxation was severely reduced in diabetic animal aortas compared to controls; sarpogrelate treatment markedly improved it. Our outcomes show that selectively blocking 5-HT2 receptors has beneficial effects on impaired cardiovascular parameters in diabetes. PMID:27659784

  11. Tricyclic analogs cyclobenzaprine, amitriptyline and cyproheptadine inhibit the spinal reflex transmission through 5-HT(2) receptors.

    PubMed

    Honda, Motoko; Nishida, Takashi; Ono, Hideki

    2003-01-01

    The centrally acting muscle relaxant cyclobenzaprine decreases the amplitude of monosynaptic reflex potentials by inhibiting the facilitatory descending serotonergic influences in the spinal cord. Interestingly, the structure of cyclobenzaprine is much similar to those of amitriptyline and cyproheptadine. In the present study, we attempted to elucidate the relationship between 5-HT(2) receptor antagonistic and inhibitory effects of cyclobenzaprine, amitriptyline, cyproheptadine and ketanserin on the spinal reflexes. Cyclobenzaprine, amitriptyline, cyproheptadine, and ketanserin significantly inhibited facilitatory effects of 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) on flexor reflexes and mono- and polysynaptic spinal reflex potentials in spinalized rats. In intact rats, these drugs significantly reduced the mono- and polysynaptic reflex potentials. 5-HT depletion significantly prevented the depression of the spinal reflex potentials induced by these drugs. These results suggest that the inhibitory effects of cyclobenzaprine, amitriptyline, and cyproheptadine on mono- and polysynaptic reflex potentials are due to the inhibition of descending serotonergic systems through 5-HT(2) receptors in the spinal cord.

  12. Effects of the 5HT antagonist cyproheptadine on neuropsychological function in chronic schizophrenia.

    PubMed

    Chaudhry, I B; Soni, S D; Hellewell, J S E; Deakin, J F W

    2002-01-01

    This study tests the hypothesis that the ability of atypical neuroleptics to improve negative symptoms is due to 5HT-receptor antagonism and enhanced frontal lobe function. We investigated the effects of cyproheptadine (a 5HT2 antagonist) on neuropsychological tests of frontal lobe functions in chronic schizophrenic patients. Eighteen stable schizophrenic patients on depot neuroleptic medication participated in a 4-week double blind crossover study. Outcome measures were clinical symptoms rating scales, neuropsychological tests (verbal fluency, Stroop colour word task, trail making) and antisaccade eye movements. During the cyproheptadine phase statistically significant improvement was seen on Stroop colour word task, verbal fluency and Trail B tests. The ability to suppress reflexive eye movement to a target light in an anti saccade task was also significantly enhanced. The patients had low clinical ratings of negative symptoms and they were unaffected by cyproheptadine. The results indicate that 5HT2C receptors selectively modulate speed and motor control mechanisms related to frontal lobe functions but this was not associated with changes in symptoms.

  13. Reward processing by the dorsal raphe nucleus: 5-HT and beyond.

    PubMed

    Luo, Minmin; Zhou, Jingfeng; Liu, Zhixiang

    2015-09-01

    The dorsal raphe nucleus (DRN) represents one of the most sensitive reward sites in the brain. However, the exact relationship between DRN neuronal activity and reward signaling has been elusive. In this review, we will summarize anatomical, pharmacological, optogenetics, and electrophysiological studies on the functions and circuit mechanisms of DRN neurons in reward processing. The DRN is commonly associated with serotonin (5-hydroxytryptamine; 5-HT), but this nucleus also contains neurons of the neurotransmitter phenotypes of glutamate, GABA and dopamine. Pharmacological studies indicate that 5-HT might be involved in modulating reward- or punishment-related behaviors. Recent optogenetic stimulations demonstrate that transient activation of DRN neurons produces strong reinforcement signals that are carried out primarily by glutamate. Moreover, activation of DRN 5-HT neurons enhances reward waiting. Electrophysiological recordings reveal that the activity of DRN neurons exhibits diverse behavioral correlates in reward-related tasks. Studies so far thus demonstrate the strong power of DRN neurons in reward signaling and at the same time invite additional efforts to dissect the roles and mechanisms of different DRN neuron types in various processes of reward-related behaviors. PMID:26286655

  14. Suppressant effects of selective 5-HT2 antagonists on rapid eye movement sleep in rats.

    PubMed

    Tortella, F C; Echevarria, E; Pastel, R H; Cox, B; Blackburn, T P

    1989-04-24

    The effects of the novel, highly selective serotonin-2 (5-HT2) antagonists, ICI 169,369 and ICI 170,809, on 24 h EEG sleep-wake activity were studied in the rat. Both compounds caused a dose-related increase in the latency to rapid eye movement sleep (REMS) and significantly suppressed cumulative REMS time up to 12 h postinjection. In contrast, neither drug disrupted slow-wave sleep continuity in as much as the latency to non-REMS (NREMS) and cumulative NREMS time were unchanged. However, at the highest dose tested (20 mg/kg) ICI 170,809 did produce a significant increase in total NREMS time during the second half of the sleep-awake cycle. These results demonstrate effects of selective 5-HT2 antagonists on sleep in rats which appear to be specific for REMS behavior, suggesting that the priming influence of serotonin on REMS may involve 5-HT2 receptor subtypes. The relationship between the REMS suppressant actions of these compounds and their consideration as therapeutic agents in depression is discussed.

  15. Differentiations of 5-HT and GAS cells in the digestive canals of Rana chensinensis tadpoles

    PubMed Central

    LI, Xin-Yi; LI, Qian; ZHANG, Yu-Hui

    2014-01-01

    In the current study, 5-nydroxytryptamine (5-HT) and gastrin (GAS) cells in the digestive canals of Rana chensinensis tadpoles at different developmental stages were investigated by immunohistochemistry. Results showed that the 5-HT cells were only detected in the duodenum before metamorphosis began, and were extensively distributed in the stomach, duodenum, small intestine, and rectum thereafter, with the highest counts found in the duodenum and rectum when metamorphosis was completed. The GAS cells were only distributed in the stomach and duodenum, and only rarely detected in the duodenum before metamorphosis began, but increased in the stomach during metamorphosis and showed zonal distribution in the gastric mucosa when metamorphosis was completed. Metamorphosis is a critical period for amphibians, during which structural and functional physiological adaptations are required to transition from aquatic to terrestrial environments. During metamorphosis, the differentiations of 5-HT cells in the gastrointestinal canals of tadpoles could facilitate mucus secretion regulation, improve digestive canal lubrication, and help watershortage food digestion in terrestrial environments. Conversely, GAS cell differentiations during metamorphosis might contribute to the digestive and absorptive function transition from herbivore to omnivore. PMID:25017753

  16. Glossopharyngeal long-term facilitation requires serotonin 5-HT2 and NMDA receptors in rats

    PubMed Central

    Cao, Ying; Liu, Chun; Ling, Liming

    2009-01-01

    Although the glossopharyngeal nerve (IX) is mainly a sensory nerve, it innervates stylopharyngeus and some other pharyngeal muscles, whose excitations would likely improve upper airway patency since electrical IX stimulation increases pharyngeal airway size. As acute intermittent hypoxia (AIH) induces hypoglossal and genioglossal long-term facilitation (LTF), we hypothesized that AIH induces glossopharyngeal LTF, which requires serotonin 5-HT2 and NMDA receptors. Integrated IX activity was recorded in anesthetized, vagotomized, paralyzed and ventilated rats before, during and after 5 episodes of 3-min isocapnic 12% O2 with 3-min intervals of 50% O2. Either saline, ketanserin (5-HT2 antagonist, 2 mg/kg) or MK-801 (NMDA antagonist, 0.2 mg/kg) was (i.v.) injected 30–60 min before AIH. Both phasic and tonic IX activities were persistently increased (both P<0.05) after AIH in vehicle, but not ketanserin or MK-801, rats. Hypoxic glossopharyngeal responses were minimally changed after either drug. These data suggest that AIH induces both phasic and tonic glossopharyngeal LTF, which requires activation of 5-HT2 and NMDA receptors. PMID:20026287

  17. Mechanisms of action of the 5-HT1B/1D receptor agonists.

    PubMed

    Tepper, Stewart J; Rapoport, Alan M; Sheftell, Fred D

    2002-07-01

    Recent studies of the pathophysiology of migraine provide evidence that the headache phase is associated with multiple physiologic actions. These actions include the release of vasoactive neuropeptides by the trigeminovascular system, vasodilation of intracranial extracerebral vessels, and increased nociceptive neurotransmission within the central trigeminocervical complex. The 5-HT(1B/1D) receptor agonists, collectively known as triptans, are a major advance in the treatment of migraine. The beneficial effects of the triptans in patients with migraine are related to their multiple mechanisms of action at sites implicated in the pathophysiology of migraine. These mechanisms are mediated by 5-HT(1B/1D) receptors and include vasoconstriction of painfully dilated cerebral blood vessels, inhibition of the release of vasoactive neuropeptides by trigeminal nerves, and inhibition of nociceptive neurotransmission. The high affinity of the triptans for 5-HT(1B/1D) receptors and their favorable pharmacologic properties contribute to the beneficial effects of these drugs, including rapid onset of action, effective relief of headache and associated symptoms, and low incidence of adverse effects. PMID:12117355

  18. Enantioselective uptake of BOF-4272, a xanthine oxidase inhibitor with a chiral sulfoxide, by isolated rat hepatocytes.

    PubMed

    Naito, S; Nishimura, M

    2001-12-01

    The transport mechanisms of the enantiomers of BOF-4272, a new drug for the treatment of hyperuricemia, were studied using freshly prepared rat hepatocytes. BOF-4272 consists of S(-) and R(+) enantiomers due to a chiral center in the sulfoxide moiety. The uptake of these BOF-4272 enantiomers by hepatocytes was found to be temperature and dose dependent. The temperature-dependent uptake of the S(-) and R(+) enantiomers showed saturation kinetics. The Km values for the S(-) and R(+) enantiomers were 59.3 and 25.7 microM, respectively, which was a significant difference (p < 0.05). However, the maximal uptake rate was comparable for both enantiomers. Metabolic inhibitors such as antimycin, oligomycin, rotenone, carbonylcyanide m-chlorophenyl hydrazone, and carbonyl cyanide-p-(trifluromethoxy)-phenylhydrazone significantly inhibited uptake of the R(+) enantiomer, but had little effect on uptake of the S(-) enantiomer. Ouabain (an inhibitor of Na+/K(+)-ATPase) and p-nitrobenzylthioinosine (NBMPR, a nucleoside transporter inhibitor) showed no significant effects on the uptake of either enantiomer. Organic anions such as taurocholate and cholate reduced the uptake of both enantiomers. These results suggest that the hepatic uptake of both BOF-4272 enantiomers is not due to simple diffusion but also involves carrier-mediated uptake. We suggest that the carrier-mediated uptake of BOF-4272 enantiomers includes both NBMPR-insensitive facilitated diffusion and an active transport system in liver plasma membrane, and that the enantioselective uptake of BOF-4272 is due to differences in affinity for the active transporter.

  19. Effects of a phospholipase A/sub 2/ inhibitor on uptake and toxicity of liposomes containing plant phosphatidylinositol

    SciTech Connect

    Jett, M.; Alving, C.R.

    1986-05-01

    Plant phosphatidylinositol (PI) has been shown by us to have a direct cytotoxic effect on cultured tumor cells but not on normal cells. Synthetic PI containing /sup 14/C-linoleic acid in the sn-2 position, also showed the same pattern of selective cytotoxicity. When the metabolic fate of synthetic PI was examined with tumor cells, the radioactivity which no longer occurred as PI, was found as either products of phospholipase A/sub 2/ (93%, free fatty acids and phosphatidylcholine) or phospholipase C (7%, diglycerides). Uptake of liposomal PI was directly correlated with cytotoxicity. They tested a variety of inhibitors to see the effect on uptake and/or cytotoxicity of plant PI. General metabolic inhibitors such as metrizamide or sodium azide did not alter cellular uptake of the plant PI liposomes. Inhibitors of lipoxygenase formation, such as indomethacin, also did not alter the uptake or cytotoxicity induced by plant PI. Quinacrine, an inhibitor of phospholipase A/sub 2/, decreased the uptake of the PI containing liposomes to 50% of that seen in the presence or absence of any other inhibitor. Although quinacrine is itself toxic to cells, at low concentrations of quinacrine, plant PI did not show the same degree of cytotoxicity as in the absence of quinacrine. These data are compatible with the hypothesis that plant PI exerts cytotoxicity by serving as a substrate for phospholipase A/sub 2/.

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

    PubMed

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

    1995-10-01

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

  1. The modulation by 5-HT of glutamatergic inputs from the raphe pallidus to rat hypoglossal motoneurones, in vitro

    PubMed Central

    Bouryi, Vitali A; Lewis, David I

    2003-01-01

    Decreases in the activity of 5-HT-containing caudal raphe neurones during sleep are thought to be partially responsible for the resultant disfacilitation of hypoglossal motoneurones. Whilst 5-HT has a direct excitatory action on hypoglossal motoneurones as a result of activation of 5-HT2 receptors, microinjection of 5-HT2 antagonists into the hypoglossal nucleus reduces motor activity to a much lesser extent compared to the suppression observed during sleep suggesting other transmitters co-localised in caudal raphe neurones may also be involved. The aim of the present study was therefore to characterise raphe pallidus inputs to hypoglossal motoneurones. Whole cell recordings were made from hypoglossal motoneurones in vitro. 5-HT evoked a direct membrane depolarisation (8.45 ± 3.8 mV, P < 0.001) and increase in cell input resistance (53 ± 40 %, P < 0.001) which was blocked by the 5-HT2 antagonist, ritanserin (2.40 ± 2.7 vs. 7.04 ± 4.6 mV). Stimulation within the raphe pallidus evoked a monosynaptic EPSC that was significantly reduced by the AMPA/kainateantagonist, NBQX (22.8 ± 16 % of control, P < 0.001). In contrast, the 5-HT2 antagonist, ritanserin, had no effect on the amplitude of these EPSCs (106 ± 31 % of control, P = n.s.). 5-HT reduced these EPSCs to 50.0 ± 13 % of control (P < 0.001), as did the 5-HT1A agonist, 8-OH-DPAT (52.5 ± 17 %, P < 0.001) and the 5-HT1B agonist, CP 93129 (40.6 ± 29 %, P < 0.01). 8-OH-DPAT and CP 93129 increased the paired pulse ratio (1.38 ± 0.27 to 1.91 ± 0.54, P < 0.05 & 1.27 ± 0.08 to 1.44 ± 0.13, P < 0.01 respectively) but had no effect on the postsynaptic glutamate response (99 ± 4.4 % and 100 ± 2.5 %, P = n.s.). They also increased the frequency (P < 0.001), but not the amplitude, of miniature glutamatergic EPSCs in hypoglossal motoneurones. These data demonstrate that raphe pallidus inputs to hypoglossal motoneurones are predominantly glutamatergic in nature, with 5-HT decreasing the release of glutamate from

  2. 5-HT-1A receptor-mediated modulation of medullary expiratory neurones in the cat.

    PubMed Central

    Lalley, P M; Bischoff, A M; Richter, D W

    1994-01-01

    The involvement of the 5-HT-1A receptor in serotoninergic responses of stage 2 expiratory (E-2) neurones was investigated in pentobarbitone-anaesthetized, mechanically ventilated cats. The specific agonist of the 5-HT-1A receptor, 8-hydroxy-diproplaminotetralin (8-OH-DPAT), administered systemically or by ionophoresis directly on to the neurones, had a clear depressant effect. Administration of 8-OH-DPAT at doses of 10-50 micrograms kg-1 (I.V.) increased the membrane hyperpolarizations of E-2 neurones during the inspiratory and postinspiratory phases, and shortened their duration of activity in association with shortening of phrenic nerve activity. Discharges of E-2 neurones were also less intense. At doses of 50-90 micrograms kg-1, 8-OH-DPAT reduced or abolished inspiratory hyperpolarizations, and reduced expiratory depolarizations of membrane potential and discharge in parallel with inhibition of phrenic nerve discharges. The effects of the larger doses were reversed by I.V. injection of NAN-190, an antagonist at the 5-HT-1A receptor. Dose-dependent effects on the membrane potential and discharge of E-2 neurones, but not on phrenic nerve activity, were also seen by ionophoretic administration of 8-OH-DPAT on to E-2 neurones. At low currents, ejection of 8-OH-DPAT hyperpolarized the neurones without affecting the duration of inspiratory hyperpolarization and expiratory depolarization. This hyperpolarization depressed the intensity and the duration of expiratory discharges. Ejection with larger currents hyperpolarized the E-2 neurones further, and depressed expiratory depolarization leading to blockade of expiratory discharges. The effects on membrane potential were accompanied by decreased neuronal input resistance. This depressed the excitability of E-2 neurones as tested by discharge evoked by intracellular current injection. The amplitudes of action potentials decreased in parallel with the changes in input resistance. The effects were attributed to a

  3. Pharmacological analysis of G-protein activation mediated by guinea-pig recombinant 5-HT1B receptors in C6-glial cells: similarities with the human 5-HT1B receptor

    PubMed Central

    Pauwels, Petrus J; Wurch, Thierry; Palmier, Christiane; Colpaert, Francis C

    1998-01-01

    The guinea-pig recombinant 5-hydroxytryptamine1B (gp 5-HT1B) receptor stably transfected in rat C6-glial cells was characterized by monitoring G-protein activation in a membrane preparation with agonist-stimulated [35S]-GTPγS binding. The intrinsic activity of 5-HT receptor ligands was compared with that determined previously at the human recombinant 5-HT1B (h 5-HT1B) receptor under similar experimental conditions.Membrane preparations of C6-glial/gp 5-HT1B cells exhibited [3H]-5-carboxamidotryptamine (5-CT) and [3H] - N- [4-methoxy-3,4 - methylpiperazin-1-yl) phenyl] -3 - methyl - 4-(4 - pyridinyl)benzamide (GR 125743) binding sites with a pKd of 9.62 to 9.85 and a Bmax between 2.1 to 6.4 fmol mg−1 protein. The binding affinities of a series of 5-HT receptor ligands determined with [3H]-5-CT and [3H]-GR 125743 were similar. Ligand affinities were comparable to and correlated (r2: 0.74, P<0.001) with those determined at the recombinant h 5-HT1B receptor.[35S]-GTPγS binding to membrane preparations of C6-glial/gp 5-HT1B cells was stimulated by the 5-HT receptor agonists that were being investigated. The maximal responses of naratriptan, zolmitriptan, sumatriptan, N-methyl-3-[pyrrolidin-2(R)-ylmethyl]-1H-indol-5-ylmethylsulphonamide (CP122638), rizatriptan and dihydroergotamine were between 0.76 and 0.85 compared to 5-HT. The potency of these agonists showed a positive correlation (r2: 0.72, P=0.015) with their potency at the recombinant h 5-HT1B receptor. 1-naphthylpiperazine, (±)-cyanopindolol and (2′-methyl-4′-(5-methyl[1,2,4] oxadiazole-3-yl)biphenyl-4-carboxylic acid [4-methoxy-3-(4-methylpiperazin-1-yl)phenyl]amide (GR 127935) elicited an even smaller response (Emax: 0.32 to 0.63).The ligands 1′-methyl-5-(2′-methyl-4′-(5-methyl-1,2,4-oxadiazole-3-yl) biphenyl-4-carbonyl)-2,3,6,7-tetrahydrospiro [furo[2,3-f]indole-3-spiro-4′-piperidine] (SB224289), methiothepin and ritanserin displayed inhibition of basal [35S

  4. Pharmacological analysis of G-protein activation mediated by guinea-pig recombinant 5-HT1B receptors in C6-glial cells: similarities with the human 5-HT1B receptor.

    PubMed

    Pauwels, P J; Wurch, T; Palmier, C; Colpaert, F C

    1998-01-01

    1. The guinea-pig recombinant 5-hydroxytryptamine1B (gp 5-HT1B) receptor stably transfected in rat C6-glial cells was characterized by monitoring G-protein activation in a membrane preparation with agonist-stimulated [35S]-GTPgammaS binding. The intrinsic activity of 5-HT receptor ligands was compared with that determined previously at the human recombinant 5-HT1B (h 5-HT1B) receptor under similar experimental conditions. 2. Membrane preparations of C6-glial/gp 5-HT1B cells exhibited [3H]-5-carboxamidotryptamine (5-CT) and [3H]-N-[4-methoxy-3,4-methylpiperazin-1-yl) phenyl]-3-methyl-4-(4-pyridinyl)benzamide (GR 125743) binding sites with a pKd of 9.62 to 9.85 and a Bmax between 2.1 to 6.4 fmol mg(-1) protein. The binding affinities of a series of 5-HT receptor ligands determined with [3H]-5-CT and [3H]-GR 125743 were similar. Ligand affinities were comparable to and correlated (r2: 0.74, P<0.001) with those determined at the recombinant h 5-HT1B receptor. 3. [35S]-GTPgammaS binding to membrane preparations of C6-glial/gp 5-HT1B cells was stimulated by the 5-HT receptor agonists that were being investigated. The maximal responses of naratriptan, zolmitriptan, sumatriptan, N-methyl-3-[pyrrolidin-2(R)-ylmethyl]-1H-indol-5-ylmethyl sulphonamide (CP 122638), rizatriptan and dihydroergotamine were between 0.76 and 0.85 compared to 5-HT. The potency of these agonists showed a positive correlation (r2: 0.72, P=0.015) with their potency at the recombinant h 5-HT1B receptor. 1-naphthylpiperazine, (+/-)-cyanopindolol and (2'-methyl-4'-(5-methyl[1,2,4] oxadiazole-3-yl)biphenyl-4-carboxylic acid [4-methoxy-3-(4-methylpiperazin-1-yl)phenyl]amide (GR 127935) elicited an even smaller response (Emax: 0.32 to 0.63). 4. The ligands 1'-methyl-5-(2'-methyl-4'-(5-methyl-1,2,4-oxadiazole-3-yl) biphenyl-4-carbonyl)-2,3,6,7tetrahydrospiro [furo[2,3-f]indole-3-spiro-4'-piperidine] (SB224289), methiothepin and ritanserin displayed inhibition of basal [35S]-GTPgammaS binding at concentrations

  5. Posttranslational regulation of TPH1 is responsible for the nightly surge of 5-HT output in the rat pineal gland.

    PubMed

    Huang, Zheping; Liu, Tiecheng; Chattoraj, Asamanja; Ahmed, Samreen; Wang, Michael M; Deng, Jie; Sun, Xing; Borjigin, Jimo

    2008-11-01

    Serotonin (5-hydroxytryptamine, 5-HT), a precursor for melatonin production, is produced abundantly in the pineal gland of all vertebrate animals. The synthesis of 5-HT in the pineal gland is rate limited by tryptophan hydroxylase 1 (TPH1) whose activity displays a twofold increase at night. Earlier studies from our laboratory demonstrate that pineal 5-HT secretion exhibits dynamic circadian rhythms with elevated levels during the early night, and that the increase is controlled by adrenergic signaling at night. In this study, we report that (a) 5-HT total output from the pineal gland and TPH1 protein levels both display diurnal rhythms with a twofold increase at night; (b) stimulation of cAMP signaling elevates 5-HT output in vivo; (c) 5-HT total output and TPH1 protein content in rat pineal gland are both acutely inhibited by light exposure at night. Consistent with these findings, molecular analysis of TPH1 protein revealed that (a) TPH1 is phosphorylated at the serine 58 in vitro and in the night pineal gland; and (b) phosphorylation of TPH1 at this residue is required for cAMP-enhanced TPH1 protein stability. These data support the model that increased nocturnal 5-HT synthesis in the pineal gland is mediated by the phosphorylation of TPH1 at the serine 58, which elevates the TPH1 protein content and activity at night.

  6. A human serotonin 1D receptor variant (5HT1D beta) encoded by an intronless gene on chromosome 6.

    PubMed Central

    Demchyshyn, L; Sunahara, R K; Miller, K; Teitler, M; Hoffman, B J; Kennedy, J L; Seeman, P; Van Tol, H H; Niznik, H B

    1992-01-01

    An intronless gene encoding a serotonin receptor (5HT1D beta) has been cloned and functionally expressed in mammalian fibroblast cultures. Based on the deduced amino acid sequence, the gene encodes a 390-amino acid protein displaying considerable homology, within putative transmembrane domains (approximately 75% identity) to the canine and human 5HT1D receptors. Membranes prepared from CHO cells stably expressing the receptor bound [3H]serotonin with high affinity (Kd 4 nM) and displayed a pharmacological profile consistent, but not identical, with that of the characterized serotonin 5HT1D receptor. Most notably, metergoline and serotonergic piperazine derivatives, as a group, display 3- to 8-fold lower affinity for the 5HT1D beta receptor than for the 5HT1D receptor, whereas both receptors display similar affinities for tryptamine derivatives, including the antimigraine drug sumatriptan. Northern blot analysis revealed an mRNA of approximately 5.5 kilobases expressed in human and monkey frontal cortex, medulla, striatum, hippocampus and amygdala but not in cerebellum, olfactory tubercle, and pituitary. The 5