5-HT1A Receptor mRNA Research Articles

MicroRNA-Dependent Control of Serotonin-Induced Pulmonary Arterial Contraction

Background: Serotonin (5-HT) is considered to play a role in pulmonary arterial hypertension by regulating vascular remodeling and smooth muscle contractility. Here, arteries from mice with inducible and smooth muscle-specific deletion of Dicer were used to address mechanisms by which microRNAs control 5-HT-induced contraction. Methods: Mice were used 5 weeks after Dicer deletion, and pulmonary artery contractility was analyzed by wire myography. Results: No change was seen in right ventricular systolic pressure following dicer deletion, but systemic blood pressure was reduced. Enhanced 5-HT-induced contraction in Dicer KO pulmonary arteries was associated with increased 5-HT2A receptor mRNA expression whereas 5-HT1B and 5-HT2B receptor mRNAs were unchanged. Contraction by the 5-HT2A agonist TCB-2 was increased in Dicer KO as was the response to the 5-HT2B agonist BW723C86. Effects of Src and protein kinase C inhibition were similar in control and KO arteries, but the effect of inhibition of Rho kinase was reduced. We identified miR-30c as a potential candidate for 5-HT2A receptor regulation as it repressed 5-HT2A mRNA and protein. Conclusion: Our findings show that 5-HT receptor signaling in the arterial wall is subject to regulation by microRNAs and that this entails altered 5-HT2A receptor expression and signaling.

Antidepressive-like effect of imperatorin from Angelica dahurica in prenatally stressed offspring rats through 5-hydroxytryptamine system.

Adolescence is a time of continued brain maturation, particularly in limbic and cortical regions, which undoubtedly plays a role in the physiological and emotional changes. Prenatally stressed offspring rats were used to investigate the potential antidepressive-like effects of imperatorin (IMP) extracted from the root of radix angelica. After 4 weeks of treatment of IMP, behavioral tests (sucrose-preference test, forced-swimming test, and open-field test) were measured. 5-hydroxytryptamine (5-HT) concentration in the hippocampus and frontal cortex was measured using an enzyme-linked immunosorbent assay. Serotonin transporters (5-HTT) and 5-HT1A receptor (5-HT1AR) mRNA expression in the hippocampus and frontal cortex were also determined by real-time PCR. Administration with IMP (15 and 30 mg/kg/day, intragastrically) for 28 days markedly increased the percentage of sucrose (anhedonia), decreased the immobility time, and increased the number of total crossings, center crossings, rearing, and grooming in the male prenatally stressed offspring. Meanwhile, we found that 5-HT concentration in the hippocampus and frontal cortex was significantly increased in the IMP-treated group. Subsequently, we found significantly decreased 5-HTT and increased 5-HT1AR mRNA expressions in the hippocampus and frontal cortex after IMP treatment in the prenatally stressed male offspring. IMP showed antidepressive-like effects and increased 5-HT concentration in male prenatally stressed offspring, suggesting that IMP could be of therapeutic use in preventing depressive-like behavior in adolescence.

Increased levels of 5HT2A receptor mRNA expression in peripheral blood mononuclear cells of patients with major depression: correlations with severity and duration of illness

Background: Neuroimaging, immunologic, and pharmacologic studies have emphasized the role of 5-HT2A and 5-HT3A serotonin receptors in the pathophysiology of major depression.Aim: The aim of this study was to measure the relative expression of 5-HT2A and 5-HT3A receptor mRNA in peripheral blood mononuclear cells (PBMCs) of patients with major depressive disorder (MDD).Method: 5-HT2A and 5-HT3A receptor mRNA expressions were examined in PBMCs of 25 medication-naïve-patients with MDD, 25 medication-free MDD patients, and 25 healthy controls. 5-HT2A and 5-HT3A receptor mRNA expressions were measured using real-time quantitative PCR. This study evaluated patients’ clinical symptoms using the Hamilton Depression Rating Scale-17 items (HDRS) and the Beck Depression Inventory (BDI).Results: Relative 5-HTR2A mRNA expression was significantly higher in PBMCs of all MDD patients when compared with healthy controls (Z = −3.875, p < 0.05). However, there was no significant difference in the relative levels of 5-HTR3A mRNA expression in PBMCs of all MDD patients when compared with healthy controls (Z = −1.328, p > 0.05). MDD patients showed significant correlations between 5-HTR2A mRNA expression and HDRS scores (rs = 0.902, p < 0.001) and BDI scores (rs = 0.878, p < 0.001).Conclusion: This study showed that depressed patients, irrespective of treatment, have higher 5-HTR2A mRNA levels in PBMCs than healthy subjects. It also provided evidence that 5-HTR2A mRNA levels in PBMCs of MDD patients could be associated with the severity of depression and the duration of the illness.

Traumatic shock causes elevation of the serotonin 5-HT2B receptor mRNA level in rat aorta

Previously we have shown that at traumatic shock in rats the force of contraction of isolated aorta in response to angiotensin II, vasopressin, endothelin 1, or norepinephrine is decreased. On the contrary, vasoconstriction caused by serotonin is increased. A possible reason of the alterations of neuroendocrine regulation of vascular tone in shock may be a change in the expression of the receptors of these agonists in blood vessels. In the present study, using real-time PCR, we demonstrated that a day after injury the contents of mRNA encoding receptors V1A for vasopressin, ETA for endothelin 1, and AT1 for angiotensin II are not changed in aorta. There was a slight increase of the serotonin 5-HT2A receptor mRNA (36 ± 16%; p = 0.41). The level of the 5-HT2B receptor mRNA in aorta, initially low (2% of the content of the mRNA of receptors 5-HT2A), after the injury increased 15.8 ± 0.3 times (p < 0.01). However, at traumatic shock there was no contraction of aorta in response to 5-HT2B receptor agonist BW723C86, while vasodilation of the isolated aorta preconstricted with norepinephrine in response to BW723C86 was similar to that of the vessel isolated from control rats. The data obtained suggest that the observed 5-HT2B receptor overexpression is not related to the increased serotonin-induced vasoconstriction and might cause other vascular pathological changes at traumatic shock.

Recruitment by the Repressor Freud-1 of Histone Deacetylase-Brg1 Chromatin Remodeling Complexes to Strengthen HTR1A Gene Repression.

Five-prime repressor element under dual repression binding protein-1 (Freud-1)/CC2D1A is genetically linked to intellectual disability and implicated in neuronal development. Freud-1 represses the serotonin-1A (5-HT1A) receptor gene HTR1A by histone deacetylase (HDAC)-dependent or HDAC-independent mechanisms in 5-HT1A-negative (e.g., HEK-293) or 5-HT1A-expressing cells (SK-N-SH), respectively. To identify the underlying mechanisms, Freud-1-associated proteins were affinity-purified from HEK-293 nuclear extracts and members of the Brg1/SMARCCA chromatin remodeling and Sin3A-HDAC corepressor complexes were identified. Pull-down assays using recombinant proteins showed that Freud-1 interacts directly with the Brg1 carboxyl-terminal domain; interaction with Brg1 required the carboxyl-terminal of Freud-1. Freud-1 complexes in HEK-293 and SK-N-SH cells differed, with low levels of BAF170/SMARCC2 and BAF57/SMARCE1 in HEK-293 cells and low-undetectable BAF155/SMARCC1, Sin3A, and HDAC1/2 in SK-N-SH cells. Similarly, by quantitative chromatin immunoprecipitation, Brg1-BAF170/57 and Sin3A-HDAC complexes were observed at the HTR1A promoter in HEK-293 cells, whereas in SK-N-SH cells, Sin3A-HDAC proteins were not detected. Quantifying 5-HT1A receptor mRNA levels in cells treated with siRNA to Freud-1, Brg1, or both RNAs addressed the functional role of the Freud-1-Brg1 complex. In HEK-293 cells, 5-HT1A receptor mRNA levels were increased only when both Freud-1 and Brg1 were depleted, but in SK-N-SH cells, depletion of either protein upregulated 5-HT1A receptor RNA. Thus, recruitment by Freud-1 of Brg1, BAF155, and Sin3A-HDAC complexes appears to strengthen repression of the HTR1A gene to prevent its expression inappropriate cell types, while recruitment of the Brg1-BAF170/57 complex is permissive to 5-HT1A receptor expression. Alterations in Freud-1-Brg1 interactions in mutants associated with intellectual disability could impair gene repression leading to altered neuronal development.

Enduring Loss of Serotonergic Control of Orbitofrontal Cortex Function Following Contingent and Noncontingent Cocaine Exposure.

Clinical descriptions of cocaine addiction include compulsive drug seeking and maladaptive decision-making despite substantial aversive consequences. Research suggests that this may result from altered orbitofrontal cortex (OFC) function and its participation in outcome-based behavior. Clinical and animal studies also implicate serotonin in the regulation of OFC function in addiction and other neuropsychiatric disorders. Here we test the hypothesis that exposure to cocaine, throughself-administration (CSA) or yoked-administration (CYA), alters the regulation of OFC function by 5-HT. Using whole-cell electrophysiology in brain slices from naïve rats we find that 5-HT1A receptors generate hyperpolarizing outward currents in layer-V OFC pyramidal neurons, and that 5-HT2A receptors increase glutamate release onto these cells. Following extended withdrawal from CSA or CYA, this 5-HT regulation of OFC activity is largely lost. In-situ hybridization of 5-HT receptor transcripts reveals that 5-HT1A receptor mRNA is unaffected and 5-HT2A receptor mRNA is significantly elevated after CSA or CYA. These results demonstrate that 5-HT control of OFC neurons is disrupted for extended periods following cocaine exposure. We hypothesize that this dysregulation of 5-HT signaling leads to enduring disruptions of OFC network activity that this is involved in impaired decision-making associated with cocaine addiction.

Exposure to manganese and lead disrupt the human placental serotonergic system

Objectives: Serotonin is crucial for placental function and fetal development. Maternal exposure to metals can interfere with the placenta functioning and fetal development. The aim of this study is to determine if low concentrations of manganese (Mn) and lead (Pb) alter placental serotonin system. Methods and results: Birth biological samples from a cohort of pregnant women were collected and Mn and Pb levels were measured in maternal and cord blood, and placenta. Expression of placental serotonin 5-HT2A receptor mRNA is lower in high-level groups of Pb and Mn in maternal blood compared to low-level groups. Placental expression of the serotonin transporter (SERT) protein is lower in high-level group of Pb in cord blood compared to low-level group. To better understand the effect of metals on the placental serotonin system, BeWo cell line (trophoblast model) was exposed to increasing concentrations of Mn and Pb. Exposure to 1 nM of Pb reduced SERT expression by 64% in BeWo cells. SERT activity in BeWo cells exposed to Mn (1000 nM) and Pb (0.01 nM) was decreased by 30% and 52%, respectively, and was accompanied by a decrease in serotonin cell level. Conclusion: This study shows that low concentrations of Mn and Pb affect placental serotonin system, which could disturb the proper course of pregnancy and fetal development.

SSRI use and clinical outcomes in epithelial ovarian cancer.

Selective serotonin reuptake inhibitor (SSRI) use is common among ovarian cancer patients. We examined the effect of SSRIs on survival and progression in ovarian cancer patients and effects of 5-HT on ovarian cancer cell (OCC) proliferation. Ovarian cancer patients from a 6-site study between 1994 and 2010 were included. Cox proportional hazards models were used for multivariate analysis. SSRI use was associated with decreased time to disease recurrence (HR 1.3, CI 1.0-1.6, p=0.03), but not overall survival (HR 1.1, CI 0.9-1.3, p=0.56). Compared to normal ovarian cells, most OCCs had elevated 5-HT2A receptor mRNA expression (up to 1600 fold greater expression). Clonogenic survival increased in cells treated with 10 uM (1.6 fold, p<0.001) and 20uM (1.9 fold, p=0.018) 5-HT. Mice receiving 5-HT injections had increases in tumor weight (p=0.07) and nodules (p=0.08) with increased Ki67 expression. Injections with sertraline doubled mean tumor weight in mice (p=0.16). 5-HT and sertraline both increased Ki67 expression in mouse tumors (p < 0.001).Patients using SSRIs had significantly decreased time to disease progression. It is possible that SSRIs alter serotonin levels in the tumor microenvironment, resulting in activation of proliferation pathways. Further characterization of serotonergic pathways in ovarian cancer is recommended to demonstrate safety of these medications.

Narcolepsy-like sleep disturbance in orexin knockout mice are normalized by the 5-HT1A receptor agonist 8-OH-DPAT.

Orexin knockout (KO) mice exhibit a phenotype that is similar to human narcolepsy, and monoamine-related compounds, such as psychostimulants and 5-HT uptake inhibitors, have been used for the treatment of narcoleptic disorders. However, little information is available regarding the pathophysiological features of orexin KO mice, particularly with respect to their narcoleptic-like disorder and how it is affected by monoamine-related compounds. The present study was designed to investigate both the nature of the neuronal changes in orexin KO mice and the therapeutic effects of monoamine-related compounds on the sleep disorder in orexin KO mice. A decrease in locomotor activity in the dark phase was observed in orexin KO mice, and psychostimulants and 5-HT-related compounds, such as 8-OH-DPAT (5-HT1A receptor agonist) and DOI (5-HT2 receptor agonist), inhibited this hypolocomotion. We also found that 5-HT1A receptor mRNA levels, but not those for 5-HT2 or dopamine receptors, were significantly decreased in the prefrontal cortex of orexin KO mice in the dark period and were accompanied by compromising the increase in 5-HT metabolite levels. In addition, the sleep disorder in orexin KO mice, as analyzed by a polysomnography during the dark period, was completely normalized by 8-OH-DPAT. These results suggest that a dysfunction of 5-HT1A receptors is involved in the narcoleptic-like sleep dysfunction in orexin KO mice, and such dysfunction may participate in orexin deficiency-induced sleep disorders. Further, the use of 5-HT1A receptor agonist could be useful for treating the sleep disorder under a deficiency of orexin.

P.1.015 Surface-based clustering of serotonergic and adrenergic receptor mRNA expression in the human cortex

Serotonin (5-hydroxytryptamine, 5-HT) has been shown to play a role in immunoregulation; however, little is known about specific subtypes of 5-HT receptors involved in peripheral immunomodulation. In the present study we used RT-PCR methods to examine the mRNA expression of 5-HT receptors in the cells of lymphoid tissues of the rat. All 13 rat 5-HT receptor genes cloned so far were examined in ex vivo isolated spleen, thymus, and peripheral blood lymphocytes, as well as in mitogen-stimulated spleen cells. Positive signals were obtained for 5-HT1B, 5-HT1F, 5-HT2A, 5-HT2B, 5-HT6, and 5-HT7 receptor mRNAs in all three compartments. Mitogen (ConA and PWM) stimulated cells additionally expressed mRNA corresponding to the 5HT-3 receptor subtype. In contrast, 5-HT1A, 5-HT1D, 5-HT2C, 5-HT4, 5-HT5A, and 5-HT5B mRNAs were not detected in any of the examined cell populations. These results may be useful as a starting point for future functional studies on immunomodulatory effects of 5-HT and may help to understand conflicting serotonergic effects on immune functions as found in the literature.

Effect of isorhynchophylline on head-shakes behavior and levels of monoamine neurotransmitter in model rats with Tourette syndrome

Objective To explore the effect of rhynchophylline and isorhynchophylline on head-shakes behavior and levels of monoamine neurotransmitter in model rats with Tourette syndrome. Methods 40 Wistar rats were randomly divided into DOI-induced head-shakes rats(HSR group), haloperidol group, rhynchophylline group and isorhynchophylline group with 10 in each group.The inhibitory effects of rhynchophylline and isorhynchophylline were estimated by observing the HSR behavior.Dopamine(DA) and 5-hydroxytryptamine(5-HT) in the rat striatum were detected by the enzyme-linked immunosorbent assay (ELISA) method.The 5-HT2A receptor mRNA expression in prefrontal lobe cortex of the rats was measured by real-time PCR. Results Compared with HSR group, the head shakes of the rats in haloperidol group and isorhynchophylline group were significantly decreased(P 0.05). There was no significant difference of head-shakes number between the haloperidol group and isorhynchophylline group(P>0.05). Compared with HSR group, DA levels in the rat striatum were significantly decreased in isorhynchophylline group and haloperidol group((152.35±5.80)μg/L vs (111.19±4.30)μg/L, (152.35±5.80)μg/L vs (126.42±3.17)μg/L, P 0.05). There was no significant change of 5-HT2A receptor mRNA expression in rat prefrontal lobe cortex in every group(P>0.05). Conclusion Isorhynchophylline may have an inhibitory effect on rats with DOI-induced HSR.Isorhynchophylline may decrease the DA levels in the rat stratum with DOI-induced HSR.Rhynchophylline has no significant inhibitory effect on head-shakes behavior and DA levels in the rat stratum with DOI-induced HSR. Key words: Rhynchophylline; Isorhynchophylline; Tourette syndrome; 5-hydroxytryptamine 2A receptor

Depression-like behaviour of MOAP-1-/- mice - altered serotonergic mechanisms

Event Abstract Back to Event Depression-like behaviour of MOAP-1-/- mice - altered serotonergic mechanisms Hui Zhao1*, Nur-Ezan Mohamed1, Su Jing Chan1, Victor C. Yu2 and Peter T. Wong1 1 National University of Singapore, Department of Pharmacology, Yong Loo Lin School of Medicine,, Singapore 2 National University of Singapore , Department of Pharmacy, Faculty of Science, Singapore Modulator of apoptosis 1 (MOAP-1), as an upstream protein of Bax, plays a key role in mediating Bax function. Bax KO mice have been reported to show depression-like behaviour. Our studies on MOAP-1-/- (KO) mice show that they exhibited similar depression-like behaviour in the force swimming test (FST) and tail suspension test (TST), when compared to wildtype (WT) controls. Here we report new findings that suggest altered serotonergic mechanisms in the MOAP-1 KO mice may underlie the depression-like behaviour. When the mice were subjected to stress in the form of 3 successive daily exposure to water, the level of expression of the tryptophan hydroxylase 2 (TPH2, the rate-limiting enzyme in the biosynthesis of serotonin) protein was significantly lower in the midbrain region of the KO mice when compared to the WT controls. Consistently, the number of TPH2-positive cells in the dorsal raphe nucleus (DRN) were observed to be significantly less in the KO mice using immunofluorescent staining. These results suggest that the KO mice were less able to respond to stress by increases in their central serotonergic activities. In support, we observed decreased plasma serotonin (5-HT) levels in KO mice when compared with WT mice. On the contrary, it is interesting to note that SERT (serotonin transporter), 5-HT1A, and 5-HT2A receptor mRNA expression levels in the midbrain remained unchanged. However, acute treatment with a single dose of the serotonin selective reuptake inhibitor fluoxetine decreased the immobility time (in the FST) of the KO mice, while that of the WT mice remained unchanged. Taken together, our findings strongly suggest that the absence of MOAP-1 in the KO mice resulted in a reduced capacity for the mice to adapt to stress through increases in central serotonergic activities. Keywords: Depression, behaviour, mouse model, midbrain, serotonergic Conference: 14th Meeting of the Asian-Pacific Society for Neurochemistry, Kuala Lumpur, Malaysia, 27 Aug - 30 Aug, 2016. Presentation Type: Poster Presentation Session Topic: 14th Meeting of the Asian-Pacific Society for Neurochemistry Citation: Zhao H, Mohamed N, Chan S, Yu VC and Wong PT (2016). Depression-like behaviour of MOAP-1-/- mice - altered serotonergic mechanisms. Conference Abstract: 14th Meeting of the Asian-Pacific Society for Neurochemistry. doi: 10.3389/conf.fncel.2016.36.00132 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 04 Aug 2016; Published Online: 11 Aug 2016. * Correspondence: Ms. Hui Zhao, National University of Singapore, Department of Pharmacology, Yong Loo Lin School of Medicine,, Singapore, Singapore, Singapore, a0123672@u.nus.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Hui Zhao Nur-Ezan Mohamed Su Jing Chan Victor C Yu Peter T Wong Google Hui Zhao Nur-Ezan Mohamed Su Jing Chan Victor C Yu Peter T Wong Google Scholar Hui Zhao Nur-Ezan Mohamed Su Jing Chan Victor C Yu Peter T Wong PubMed Hui Zhao Nur-Ezan Mohamed Su Jing Chan Victor C Yu Peter T Wong Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Effect of Chaihu-Shugan-San on the mRNA expression of the 5-HT1A receptor and cellular proliferation in the hippocampus of epileptic rats with depression.

Chaihu-Shugan-San (CHSGS) is a herbal preparation that has been shown to effectively relieve neurologic impairment and reduce depression. However, the efficacy of CHSGS in the treatment of patients with epilepsy with depression is unknown. Therefore, in the present study, adult rats were exposed to chronic mild stress following the establishment of chronic pilocarpine-induced epilepsy. Subsequently, a sucrose consumption test and open-field test (OFT) were performed to assess depression-like behavior. Rats were randomly divided into four groups: Control, model, fluoxetine (1.8 g/kg) and CHSGS (2.7 g/kg) groups. The control and model groups received normal saline. The mRNA expression levels of the 5-hydroxytryptamine 1A (5-HT1A) receptor and the number of 5-bromo-2′-deoxyuridine (BrdU)-labeled cells in the hippocampal dentate gyrus were detected using reverse transcription-quantitative polymerase chain reaction and immunohistochemical analysis, respectively. Treatment administration was conducted by once daily intragastric perfusion for 28 days. The mRNA expression levels of the 5-HT1A receptor, the number of BrdU-labeled cells in the hippocampal dentate gyrus, the consumption of sucrose, and frequency of vertical and horizontal movement scores in the OFT were enhanced in the fluoxetine and CHSGS groups compared with the model group (P<0.05). However, no statistically significant difference was detected between the fluoxetine and CHSGS groups. These data suggest that CHSGS is able to increase the expression of 5-HT1A receptor mRNA and cellular proliferation in the hippocampal dentate gyrus in epileptic rats with depression, and thus effectively improve certain symptoms of depression.

Expression of 5-Hydroxytryptamine Receptors in Human Urinary Bladders with Benign Prostatic Hyperplasia

This study investigated the mRNA expression pattern and distribution of 5-hydroxytryptamine (5-HT) receptors 5-HT2A, 5-HT2B, 5-HT3A, 5-HT4, and 5-HT7 within the urothelium and detrusor of normal bladder tissue and in the urothelium of bladders from patients with benign prostatic hyperplasia (BPH). Normal urinary bladder specimens were obtained from 13 patients undergoing radical cystectomy due to bladder cancer (normal group) and BPH specimens were obtained from 27 benign prostatic obstruction patients receiving transurethral prostatectomy or retropubic prostatectomy. Receptor subtype mRNA expression was determined by real-time reverse transcription polymerase chain reaction on urothelium, detrusor, and whole mucosal preparations. Receptor distribution was determined by immunohistochemistry. In normal tissues, expressions of 5-HT2B and 5-HT7 receptor mRNAs in the urothelium, detrusor, and whole mucosa were greater than the average expression for all receptor subtype mRNAs. 5-HT2B receptor protein was distributed in the apical urothelium and among the detrusor smooth muscle layers. In contrast, the 5-HT7 receptors were within the urothelium middle cell layers and detrusor smooth muscle cells. The expression pattern of each 5-HT receptor subtype mRNA within the BPH urothelium was similar to that in the normal urothelium. The expression level of 5-HT2A receptor mRNA in the BPH group was significantly lower than the normal group; however, the expressions of both 5-HT3A and 5-HT7 mRNAs were significantly higher. The expressions of both 5-HT2B and 5-HT4 mRNAs were not significantly different between the normal and BPH groups. In normal urinary bladders, the expressions of both 5-HT2B and 5-HT7 mRNAs were higher compared to the 5-HT2A, 5-HT3A, and 5-HT4 mRNAs. The distributions of 5-HT2B and 5-HT7 receptors were different in the urothelium and detrusor layers. The 5-HT3A and 5-HT7 receptor mRNAs in the BPH group were significantly higher compared to the normal urothelium, while the 5-HT2A mRNA was significantly lower. Asahi Kasei Pharma Corporation.

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

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

Serotonin-mediated modulation of hypoxia-induced intracellular calcium responses in glomus cells isolated from rat carotid body

In the present study, we examined serotonin (5-HT)-induced intracellular Ca2+ ([Ca2+]i) responses to hypoxia in glomus cells isolated from carotid body (CB) of the rat. 5-HT did not induce any [Ca2+]i responses in clustered glomus cells during normoxia (21% O2), whereas, the perfusion of hypoxic solution (1% O2) induced repetitive increases in [Ca2+]i in the same specimens. The frequency and magnitude of hypoxia-induced [Ca2+]i changes observed in the glomus cells were enhanced in the presence of 5-HT, and this response was inhibited by the 5-HT2 receptor antagonist, ketanserin. Furthermore, RT-PCR analysis detected the expression of 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, 5-HT3A, and 5-HT3B receptor mRNAs in extracts of the CB. These results suggest that 5-HT increases hypoxia-induced [Ca2+]i responses in glomus cells. 5-HT may elevate hypoxic responses in glomus cells in order to increase chemosensory activity of the CB.

Neuronal and neuroendocrine mechanisms of social rank and stress coping in teleost fish

Fights for social dominance are stressful and results in an activation of the brain serotonergic system. Subordinate animals in an established dominance hierarchy are characterized by a chronic elevation of brain serotonergic activity, an effect that seems to mediate the behavioural inhibition observed in these animals. By contrast, social dominance has been associated with elevated dopaminergic activity, and dopamine (DA) has behavioural effects to some extent opposing those of serotonin (5HT). In addition to effects of the social environment, brain monoaminergic functions are controlled by genetic factors. For instance, zebrafish (Danio rerio) classified as bold, showing a propensity for being social dominant, display higher expression of DA2b receptor mRNA than shy conspecifics. In rainbow trout (Oncorhynchus mykiss) and Baltic salmon (Salmo salar) bold and shy individuals differ in the expression of 5HT1A receptor mRNA. In salmonids, bold and shy fish also show divergent effects of stress on brain 5HT neurotransmission. Personality traits are to a large extent genetically controlled. However, teleost fish are extremely plastic and it is not clear to what extent “personality related” differences in monoaminergic, and peptidergic, systems is related to heritable factors or early social interaction.

Functional Analysis of 3-Mercaptopyruvate Sulfurtransferase Using Knockout Mice

3-mercaptopyruvate sulfurtransferase (MST) transfers sulfur from 3-mercaptopyruvate (3MP) or thiosulfate to a sulfur acceptor. We developed MST-knockout (MST-KO) mice to clarify the physiological role of MST. They showed increased anxiety-like behaviors. In the prefrontal cortex and hippocampus, levels of serotonin (5-hydroxytryptamin, 5-HT) and/or serotonin metabolite, 5-hydroxyindoleacetic acid were higher in MST-KO mice than in wild-type mice and further 5-HT2A receptor mRNA was increased. Experiments using MST-KO mouse revealed that MST produces hydrogen polysulfides from 3MP and sodium sulfide and hydrogen trisulfide was also enzymatically produced.

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

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.

Prevention of 5-hydroxytryptamine2C receptor RNA editing and alternate splicing in C57BL/6 mice activates the hypothalamic-pituitary-adrenal axis and alters mood.

The 5-hydroxytryptamine2C (5-HT)2C receptor is widely implicated in the aetiology of affective and eating disorders as well as regulation of the hypothalamo-pituitary-adrenal axis. Signalling through this receptor is regulated by A-to-I RNA editing, affecting three amino acids in the protein sequence, with unedited transcripts encoding a receptor (INI) that, in vitro, is hyperactive compared with edited isoforms. Targeted alteration (knock-in) of the Htr2c gene to generate ‘INI’ mice with no alternate splicing, solely expressing the full-length unedited isoform, did not produce an overt metabolic phenotype or altered anxiety behaviour, but did display reduced depressive-like and fear-associated behaviours. INI mice exhibited a hyperactive hypothalamo-pituitary-adrenal axis, with increased nadir plasma corticosterone and corticotrophin-releasing hormone expression in the hypothalamus but responded normally to chronic stress and showed normal circadian activity and activity in a novel environment. The circadian patterns of 5-HT2C receptor mRNA and mbii52, a snoRNA known to regulate RNA editing and RNA splicing of 5-HT2C receptor pre-mRNA, were altered in INI mice compared with wild-type control mice. Moreover, levels of 5-HT1A receptor mRNA were increased in the hippocampus of INI mice. These gene expression changes may underpin the neuroendocrine and behavioural changes observed in INI mice. However, the phenotype of INI mice was not consistent with a globally hyperactive INI receptor encoded by the unedited transcript in the absence of alternate splicing. Hence, the in vivo outcome of RNA editing may be neuronal cell type specific.