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Mohammadi Amirabad L, Ahangari G, Derakhshan Deilami G. Significant changes of 5-Hydroxytriptamine 3A receptor gene expression in peripheral blood mononuclear cells of allergic asthmatic patients. Iran J Allergy Asthma Immunol 2014; 13:33-39. [PMID: 24338226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 10/06/2013] [Accepted: 03/03/2013] [Indexed: 06/03/2023]
Abstract
Asthma is a chronic inflammatory disorder of the airways. The stress is a factor for asthma which indicates a disorder in the function of communicational mediators of nervous and immunological systems such as neurotransmitters. A study indicated that blood serotonin concentration increases in asthmatic patients. Other study indicates that one kind of the serotonin receptors, named 5HT3A, on PBMCs causes secretion of series of pro-inflammatory cytokines which play important roles in allergic asthma disease. Thus, we evaluated the ratio expression level of 5HT3A subtype receptors in asthma. The Peripheral Blood Mononuclear Cells were separated from whole blood of 30 allergic asthmatic patients and 30 normal controls by a gradient density centrifugation technique, then the total cellular RNA was extracted and the cDNA was synthesized. This process was followed by real-time PCR using primer pairs specific for 5-hydroxytryptamine 3A subtype receptor mRNA and beta-actin as internal control. Results revealed that relative gene expression of 5-hydroxytryptamine 3A subtype receptor increased significantly in Peripheral Blood Mononuclear Cells of patients with asthma in comparison with normal individuals. To conclude, considering 5-hydroxytryptamine 3A subtype receptor role in accomplishment of asthma symptoms, this increase in its expression may exacerbate the seriousness of asthma disease.
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Affiliation(s)
- Leila Mohammadi Amirabad
- Department of Medical Genetics, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran.
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Matsumoto K, Nakajima T, Sakai H, Kato S, Sagara A, Arakawa K, Tashima K, Narita M, Horie S. Increased expression of 5-HT3 and NK 1 receptors in 5-fluorouracil-induced mucositis in mouse jejunum. Dig Dis Sci 2013; 58:3440-51. [PMID: 23695873 DOI: 10.1007/s10620-013-2709-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/26/2013] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Although 5-fluorouracil (5-FU) is a widely used as chemotherapy agent, severe mucositis develops in approximately 80% of patients. 5-FU-induced small intestinal mucositis can cause nausea and vomiting. The current study was designed to investigate peripheral alterations due to the 5-FU-induced mucositis of neuronal and non-neuronal 5-HT3 and NK1 receptor expression by immunohistochemical analysis. METHODS 5-FU was administered by i.p. injection to C57BL/6 mice. After 4 days, segments of the jejunum were removed. The specimens were analyzed by immunohistochemistry, real-time PCR, and enzyme immunoassay. RESULTS The numbers of 5-HT3 receptor immunopositive cells and nerve fibers in mucosa were increased by 5-FU treatment. The 5-HT3 receptor immunopositive cell bodies were found only in jejunal submucosa and myenteric plexus in the 5-FU-treated mice. The numbers of NK1 receptor cells in mucosa and immunopositive expression of NK1 receptors in deep muscular plexus were dramatically increased in 5-FU-treated mice. Real-time PCR demonstrated that 5-FU treatment significantly increased mRNA levels of 5-HT3A, 5-HT3B, and NK1 receptors. The amounts of 5-HT and substance P increased after 5-FU treatment. The 5-HT3 or NK1 receptor immunopositive cells colocalized with both 5-HT and substance P. Furthermore, 5-HT3 and NK1 receptors colocalized with CD11b. CONCLUSIONS The 5-HT3 and NK1 immunopositive macrophages and mucosal mast cells in lamina propria release 5-HT and substance P, which in turn activate their corresponding receptors on mucosal cells in autocrine and paracrine manners. It is assumed to result in the release of 5-HT and substance P in mucosa.
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Affiliation(s)
- Kenjiro Matsumoto
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Josai International University, 1 Gumyo, Togane, Chiba, 283-8555, Japan,
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Huang Y, Morozov A. Hippocampal deletion of BDNF gene attenuates gamma oscillations in area CA1 by up-regulating 5-HT3 receptor. PLoS One 2011; 6:e16480. [PMID: 21298058 PMCID: PMC3027673 DOI: 10.1371/journal.pone.0016480] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 12/21/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Pyramidal neurons in the hippocampal area CA3 express high levels of BDNF, but how this BDNF contributes to oscillatory properties of hippocampus is unknown. METHODOLOGY/PRINCIPAL FINDINGS Here we examined carbachol-induced gamma oscillations in hippocampal slices lacking BDNF gene in the area CA3. The power of oscillations was reduced in the hippocampal area CA1, which coincided with increases in the expression and activity of 5-HT3 receptor. Pharmacological block of this receptor partially restored power of gamma oscillations in slices from KO mice, but had no effect in slices from WT mice. CONCLUSION/SIGNIFICANCE These data suggest that BDNF facilitates gamma oscillations in the hippocampus by attenuating signaling through 5-HT3 receptor. Thus, BDNF modulates hippocampal oscillations through serotonergic system.
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Affiliation(s)
- Ying Huang
- Unit on Behavioral Genetics, Laboratory of Molecular Pathophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Alexei Morozov
- Unit on Behavioral Genetics, Laboratory of Molecular Pathophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America
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Chetty N, Coupar IM, Chess-Williams R, Kerr KP. Demonstration of 5-HT3 receptor function and expression in the mouse bladder. Naunyn Schmiedebergs Arch Pharmacol 2007; 375:359-68. [PMID: 17607564 DOI: 10.1007/s00210-007-0173-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 06/02/2007] [Indexed: 11/30/2022]
Abstract
The aim of this study was to demonstrate the presence of 5-HT(3) receptors in the mouse bladder and to determine their location. Bladder strips from female mice were set up in gassed Krebs-Henseleit solution at 37 degrees C and contractions recorded in response to electrical field stimulation (8 Hz, 60 V, 0.5-ms pulse duration) applied for 2 s every 50 s. The potentiating effects of 5-hydroxytryptamine (5-HT) were recorded (in the presence of 1-microM methysergide and 1-microM GR125487 to isolate the 5-HT(3) receptor response), and contractions were expressed as a percentage of the response to 0.1-M KCl. Responses to (5-HT) were also obtained in the presence of the 5-HT(3) receptor antagonist, ondansetron. RT-PCR was used to detect the expression of the 5-HT(3A) and 5-HT(3B) subunit transcripts of the mouse 5-HT(3) receptor. 5-HT and 5-HT(3) receptor agonists caused concentration-dependent increases in the force of neurogenic contractions without affecting the baseline tone. The rank order of potency was: meta-chloro-phenylbiguanide (m-CPB) = 5-HT > 2-methyl-5-HT (2m5-HT) = 1-phenylbiguanide (1-PBG). The respective pEC(50) values were: 6.42 +/- 0.2 = 5.95 +/- 0.19 > 5.35 +/- 0.12 = 5.14 +/- 0.13. m-CPB acted as a full agonist (E (max) = 40.65 +/- 3.81% KCl), but both 2m5-HT and 1-PBG acted as lower potency partial agonists. Ondansetron (30, 100, 300 nM) caused concentration-related rightward displacements to the concentration-effect curve to 5-HT. Nonlinear regression analysis of the effect of the ondansetron concentrations on the pEC(50) values produced a pK(B) value of 8.29 +/- 0.22. Desensitization of sensory nerves to the contractile effect of capsaicin (10 microM for 60 min) did not alter the ability of 5-HT to potentiate neurogenic contractions. 5-HT (3 microM) inhibited contractions induced by direct muscle stimulation (lignocaine, 300 microM and 10-ms pulse width). m-CPB also caused the same effect with a pIC(50) of 6.62 +/- 0.10 and an E (max) of 48.03 +/- 2.25%. The concentration-response curve to m-CPB was shifted rightwards by ondansetron (1 microM) giving an apparent pK(B) value of 8.15 +/- 0.33. mRNA for both the 5-HT(3A) and 5-HT(3B) receptor subunits was detected in the detrusor as well as the mucosa with a greater relative expression of the 5-HT(3A) subunit in both layers. This study demonstrates that 5-HT mediates enhanced neurogenic contractions of the mouse bladder muscle by an action at 5-HT(3) receptors located prejunctionally on nonsensory nerve elements. Additionally, an inhibitory postjunctional population of the 5-HT(3) receptor was identified. The presence of the 5-HT(3) receptor was confirmed by the expression of both 5-HT(3A) and 5-HT(3B) receptor subunits of the 5-HT(3) receptor.
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Affiliation(s)
- N Chetty
- Department of Pharmaceutical Biology, Victorian College of Pharmacy, Monash University, Parkville, Victoria 3052, Australia
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Ballaz SJ, Akil H, Watson SJ. Analysis of 5-HT6 and 5-HT7 receptor gene expression in rats showing differences in novelty-seeking behavior. Neuroscience 2007; 147:428-38. [PMID: 17543469 DOI: 10.1016/j.neuroscience.2007.04.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Revised: 04/14/2007] [Accepted: 04/16/2007] [Indexed: 11/22/2022]
Abstract
Sensation-seeking is a human personality trait associated with a greater propensity to use psychoactive substances. A rat model showing face validity of this human trait has been developed. The model is based on the variety of behavioral responses that rats exhibit in a novel and inescapable environment, with some animals (high-responders, HR) being highly active, and others (low-responders, LR) showing less exploration. More active rats (HR) also show increased drug-taking and decreased anxiety-like behavior. There is evidence that response to novelty may rely on differential 5-HT-mediated neurotransmission. This research focuses on the recently discovered 5-HT6 and 5-HT7 receptors which share affinity for neuroleptic drugs and hallucinogens. To date, emerging evidence suggests that 5-HT6 and 5-HT7 may be involved in cognition and mood regulation, respectively. To further our knowledge of their behavioral attributes, we compared patterns of gene expression for these receptors in the brains of HR and LR rats. As a control, gene expression for the 5-HT3 receptor was investigated because its contribution to anxiety and addiction is only weakly demonstrated. Transcript levels for 5-HT6 in the olfactory tubercle inversely correlated with the level of locomotion in a novel environment. Phenotype differences in mRNA signal for 5-HT6 showed a complex pattern in the dentate gyrus. LR rats were statistically higher in the most anterior region of the dentate gyrus, while HR rats were higher in median areas of the dentate gyrus. Levels of 5-HT7 transcript in HR rats were significantly lower than LR rats in pivotal areas for information trafficking, such as thalamo-cortical projection areas and dorsal hippocampus. By contrast, phenotype differences in 5-HT3 expression were not found in areas of the limbic cortex and mesolimbic system. Taken together, these results provide new insight into the potential contribution of 5-HT to novelty-seeking behavior and associated behaviors such as substance abuse.
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MESH Headings
- Animals
- Autoradiography
- Brain Chemistry/genetics
- Brain Chemistry/physiology
- Dentate Gyrus/metabolism
- Dentate Gyrus/physiology
- Emotions/physiology
- Exploratory Behavior/physiology
- Gene Expression/physiology
- Image Processing, Computer-Assisted
- In Situ Hybridization
- Male
- Motor Activity/physiology
- Olfactory Bulb/metabolism
- Olfactory Bulb/physiology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Receptors, Serotonin/biosynthesis
- Receptors, Serotonin/genetics
- Receptors, Serotonin, 5-HT3/biosynthesis
- Receptors, Serotonin, 5-HT3/genetics
- Thalamus/metabolism
- Thalamus/physiology
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Affiliation(s)
- S J Ballaz
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109-0720, USA.
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Quirk PL, Siegel RE. The serotonin type 3A receptor facilitates luteinizing hormone release and LHbeta promoter activity in immortalized pituitary gonadotropes. Endocrine 2005; 27:37-43. [PMID: 16077169 DOI: 10.1385/endo:27:1:037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 04/14/2005] [Accepted: 04/28/2005] [Indexed: 11/11/2022]
Abstract
The 5-hydroxytryptamine type 3A receptor (5-HT3AR) is a ligand-gated cation channel activated by serotonin. This receptor is expressed throughout the nervous system as well as in the pituitary gland. Although it has been documented that the 5-HT3AR modulates exocytosis in neurons, its role in the pituitary gland has not been determined. Previous research has shown that the 5-HT3AR modulates circulating gonadotropin levels in vivo. It is unclear, however, if its activation in the pituitary gland mediates these effects or if receptors elsewhere in the hypothalamus-pituitary-gondal axis are responsible. To investigate the potential for the 5-HT3AR to modulate gonadotropin release from pituitary gonadotropes, the gonadotrope-derived LbetaT2 cell line was used as a model system and radioimmunoassays were employed to investigate how 5-HT3AR activation influences luteinizing hormone (LH) release. Our studies demonstrate that gonadotropin releasing hormone (GnRH)-stimulated LH release was decreased by the 5-HT3AR-specific antagonist MDL 72222 in a concentration-dependent manner. In addition, it was found that overexpressing the 5-HT3AR in LbetaT2 cells enhanced both basal and GnRH-stimulated LH release and also increased LHbeta gene promoter activity. These results suggest that the 5-HT3AR may participate in the hypothalamus-pituitary-gonadal axis at the level of the pituitary gonadotrope to mediate pituitary hormone release.
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Affiliation(s)
- Phillip L Quirk
- Medical Sciences Program, Indiana Universtiy, Bloomington, IN, USA
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Abstract
RIC-3 has been identified as a molecule essential for the recruitment of functional nicotinic acetylcholine receptors composed of alpha7, but it exhibits inhibitory effects on alpha4beta2 or alpha3beta4 receptors. In this study, we investigated the role of RIC-3 in the recruitment of 5-hydroxytryptamine type 3A (5-HT(3A)) receptors to the cell surface. Although RIC-3 is not essential for the surface transport of 5-HT(3A) receptors, we found that its presence enhances both receptor transport and function in a concentration-dependent manner. RIC-3 is localized to the endoplasmic reticulum, as evidenced by co-localization with the chaperone molecule, binding protein (BiP). RIC-3 is not detected at significant levels on the cell surface when expressed alone or in the presence of 5-HT(3A). RIC-3 and 5-HT(3A) show a low level interaction that is transient (<4 h). That RIC-3 can interact with an endoplasmic reticulum-retained 5-HT(3A) construct, combined with the transient interaction observed and lack of significant surface-expressed RIC-3, suggests that RIC-3 may play a role in 5-HT(3A) receptor folding, assembly, or transport to the cell surface.
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Affiliation(s)
- Aixin Cheng
- Department of Pharmacology & Neuroscience, Ninewells Medical School, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
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Abstract
BACKGROUND Drug discrimination studies using selective antagonists and agonists have suggested that 5-HT3 receptors may modulate ethanol's discriminative stimulus effects. However, conflicting data between laboratories leaves the issue of 5-HT3 receptor involvement in ethanol's discriminative stimulus effects in question. The present study utilized transgenic mice that over-express 5-HT3 receptors in conjunction with traditional pharmacological techniques to examine the contribution of 5-HT3 receptors to ethanol's discriminative stimulus. METHODS Ten 5-HT3 over-expressing (5-HT3 OE) and 18 B6SJL wild-type (WT) mice were trained to discriminate 1.5 g/kg ethanol from saline in daily 15 min, milk reinforced operant sessions. After training, ethanol substitution and response-rate suppression dose response curves were determined for ethanol, midazolam, dizocilpine, cocaine, mCPP, MD-354, YC-30 and MDL-72222. Antagonism tests combining ethanol with MDL-72222 and ondansetron were also conducted. RESULTS The 5-HT3 OE and WT mice learned the ethanol discrimination in a comparable number of training sessions. Similar patterns of substitution were generated in both groups of mice for most test drugs. 5-HT3 OE mice were more sensitive to the rate suppressing effects of dizocilpine and MDL-72222 than were WT mice. Neither of the 5-HT3 antagonist tested significantly attenuated ethanol's discriminative stimulus effects in either 5-HT3 OE or WT mice. CONCLUSIONS The results of the present study are consistent with a minimal role of 5-HT3 receptors in transducing ethanol's discriminative stimulus effects. Over-expression of 5-HT3 receptors does not alter the relative efficacy of GABAA positive modulators or NMDA antagonists for producing ethanol-like discriminative stimulus effects. However, 5-HT3 receptor over-expression does appear to modulate the response-rate altering effects of the uncompetitive NMDA antagonist, dizocilpine, and the 5-HT3 antagonist, MDL-72222.
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MESH Headings
- Animals
- Discrimination, Psychological/drug effects
- Discrimination, Psychological/physiology
- Dose-Response Relationship, Drug
- Ethanol/pharmacology
- Gene Expression Regulation/physiology
- Mice
- Mice, Transgenic
- Reaction Time/drug effects
- Reaction Time/genetics
- Receptors, Serotonin, 5-HT3/biosynthesis
- Receptors, Serotonin, 5-HT3/genetics
- Receptors, Serotonin, 5-HT3/physiology
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Affiliation(s)
- Keith L Shelton
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298-0613, USA.
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Bhattacharya A, Dang H, Zhu QM, Schnegelsberg B, Rozengurt N, Cain G, Prantil R, Vorp DA, Guy N, Julius D, Ford APDW, Lester HA, Cockayne DA. Uropathic observations in mice expressing a constitutively active point mutation in the 5-HT3A receptor subunit. J Neurosci 2004; 24:5537-48. [PMID: 15201326 PMCID: PMC6729324 DOI: 10.1523/jneurosci.5658-03.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutant mice with a hypersensitive serotonin (5-HT)3A receptor were generated through targeted exon replacement. A valine to serine mutation (V13'S) in the channel-lining M2 domain of the 5-HT3A receptor subunit rendered the 5-HT3 receptor 70-fold more sensitive to serotonin and produced constitutive activity when combined with the 5-HT3B subunit. Mice homozygous for the mutant allele (5-HT3Avs/vs) had decreased levels of 5-HT3A mRNA. Measurements on sympathetic ganglion cells in these mice showed that whole-cell serotonin responses were reduced, and that the remaining 5-HT3 receptors were hypersensitive. Male 5-HT3Avs/vs mice died at 2-3 months of age, and heterozygous (5-HT3Avs/+) males and homozygous mutant females died at 4-6 months of age from an obstructive uropathy. Both male and female 5-HT3A mutant mice had urinary bladder mucosal and smooth muscle hyperplasia and hypertrophy, whereas male mutant mice had additional prostatic smooth muscle and urethral hyperplasia. 5-HT3A mutant mice had marked voiding dysfunction characterized by a loss of micturition contractions with overflow incontinence. Detrusor strips from 5-HT3Avs/vs mice failed to contract to neurogenic stimulation, despite overall normal responses to a cholinergic agonist, suggestive of altered neuronal signaling in mutant mouse bladders. Consistent with this hypothesis, decreased nerve fiber immunoreactivity was observed in the urinary bladders of 5-HT3Avs/vs compared with 5-HT3A wild-type (5-HT3A+/+) mice. These data suggest that persistent activation of the hypersensitive and constitutively active 5-HT3A receptor in vivo may lead to excitotoxic neuronal cell death and functional changes in the urinary bladder, resulting in bladder hyperdistension, urinary retention, and overflow incontinence.
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Pons S, Sallette J, Bourgeois JP, Taly A, Changeux JP, Devillers-Thiéry A. Critical role of the C-terminal segment in the maturation and export to the cell surface of the homopentameric alpha7-5HT3A receptor. Eur J Neurosci 2004; 20:2022-30. [PMID: 15450081 DOI: 10.1111/j.1460-9568.2004.03673.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many neurological pathologies are related to misfolded proteins. During folding and assembly in the endoplasmic reticulum, the nicotinic acetylcholine receptor (nAChR) subunits undergo several conformational changes to acquire the ability to bind ligands. After folding and maturation, by mechanisms largely unknown, receptors are exported to the cell surface. We investigated the maturational role of the extracellular C-terminal segment located at the boundary between the extracellular and the transmembrane domains. In the functional chimeric alpha7-5HT3A receptor used as a model system, amino acids from the C-terminal segment were successively deleted or mutated. Upon progressive shortening of the peptide we observed less and less alpha-bungarotoxin binding sites until no sites could be detected when the entire peptide had been deleted (chimera Del 5). Protein synthesis and pentameric assembly were not altered. In Del 5 transfected cells, pentameric receptors present in the endoplasmic reticulum were not detected on the cell surface where Del 5 proteins appeared as patches. With the Del 5 chimera, export of proteins to the cell surface diminished to about half that of wild-type. We propose that the C-terminal segment plays a double role: (i) through an interaction between the penultimate tyrosine residue of the C-terminal segment and the Cys loop of the N-terminal domain, it locks the receptor in a mature alpha-bungarotoxin binding conformation; (ii) this mature conformation, in turn, masks a retention signal present in the first transmembrane segment allowing properly assembled and matured receptors to escape to the cell surface.
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Affiliation(s)
- S Pons
- Laboratoire Récepteurs et Cognition, Département de Neuroscience, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris 15, France
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Grailhe R, de Carvalho LP, Paas Y, Le Poupon C, Soudant M, Bregestovski P, Changeux JP, Corringer PJ. Distinct subcellular targeting of fluorescent nicotinic alpha 3 beta 4 and serotoninergic 5-HT3A receptors in hippocampal neurons. Eur J Neurosci 2004; 19:855-62. [PMID: 15009132 DOI: 10.1111/j.1460-9568.2004.03153.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nicotinic acetylcholine receptors (nAChRs) and the 5-HT3 serotonin receptor subtype belong to a superfamily of neurotransmitter-gated ion channels involved in fast synaptic communication throughout the nervous system. Their trafficking to the neuron plasmalemma, as well as their targeting to specific subcellular compartments, is critical for understanding their physiological role. In order to investigate the cellular distribution of these receptors, we tagged the N-termini of alpha3beta4-nAChR subunits and the 5-HT3AR subunit with cyan and yellow fluorescent proteins (CFP, YFP). The fusion subunits were coexpressed in human embryonic kidney (HEK-293) cells, where they assemble into functional receptor channels, as well as in primary cultures of hippocampal neurons. Fluorescence microscopy of living cells revealed that the heteropentameric alpha3CFP-beta4 and YFP-alpha3beta4 receptors are mainly distributed in the endoplasmic reticulum, while the homopentameric YFP-5-HT3A receptor was localized both to the plasma membrane and within intracellular compartments. Moreover, the YFP-5-HT3A receptor was found to be targeted to the micropodia in HEK-293 cells and to the dendritic spines in hippocampal neurons, where it could be accessed by extracellularly applied specific fluorescent probes. The efficient targeting of the YFP-5-HT3A to the cytoplasmic membrane is in line with the large serotonin-elicited currents (nA range) measured by whole-cell voltage-clamp recordings in transfected HEK-293 cells. In contrast, alpha3beta4-nAChRs expressed in the same cells yielded weaker ACh-evoked responses. Taken together, the fluorescent and electrophysiological studies presented here demonstrate the predominant intracellular location of alpha3beta4-nACh receptors and the predominant expression of the 5-HT3AR in dendritic surface loci.
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Affiliation(s)
- Régis Grailhe
- Récepteurs et Cognition, Unité de recherche associée D1284, CNRS, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris, France.
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Kaya N, Shen T, Lu SG, Zhao FL, Herness S. A paracrine signaling role for serotonin in rat taste buds: expression and localization of serotonin receptor subtypes. Am J Physiol Regul Integr Comp Physiol 2004; 286:R649-58. [PMID: 14715493 DOI: 10.1152/ajpregu.00572.2003] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent advances in peripheral taste physiology now suggest that the classic linear view of information processing within the taste bud is inadequate and that paracrine processing, although undemonstrated, may be an essential feature of peripheral gustatory transduction. Taste receptor cells (TRCs) express multiple neurotransmitters of unknown function that could potentially participate in a paracrine role. Serotonin is expressed in a subset of TRCs with afferent synapses; additionally, TRCs respond physiologically to serotonin. This study explored the expression and cellular localization of serotonin receptor subtypes in TRCs as a possible route of paracrine communication. RT-PCR was performed on RNA extracted from rat posterior taste buds with 14 primer sets representing 5-HT1 through 5-HT7 receptor subtype families. Data suggest that 5-HT1A and 5-HT3 receptors are expressed in taste buds. Immunocytochemistry with a 5-HT1A-specific antibody demonstrated that subsets of TRCs were immunopositive for 5-HT1A. With the use of double-labeling, serotonin- and 5-HT1A-immunopositive cells were observed exclusively in nonoverlapping populations. On the other hand, 5-HT3-immunopositive taste receptor cells were not observed. This observation, combined with other data, suggests 5-HT3 is expressed in postsynaptic neural elements within the bud. We hypothesize that 5-HT release from TRCs activates postsynaptic 5-HT3 receptors on afferent nerve fibers and, via a paracrine route, inhibits neighboring TRCs via 5-HT1A receptors. The role of the 5-HT1A-expressing TRC within the taste bud remains to be explored.
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MESH Headings
- Animals
- Electrophoresis, Polyacrylamide Gel
- Fluorescent Antibody Technique
- Immunohistochemistry
- Male
- Paracrine Communication/physiology
- RNA/analysis
- RNA/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT1A/biosynthesis
- Receptor, Serotonin, 5-HT1A/physiology
- Receptors, Serotonin/biosynthesis
- Receptors, Serotonin/physiology
- Receptors, Serotonin, 5-HT3/biosynthesis
- Receptors, Serotonin, 5-HT3/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Serotonin/physiology
- Signal Transduction/physiology
- Spectrophotometry, Ultraviolet
- Taste Buds/metabolism
- Taste Buds/physiology
- Tissue Fixation
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Affiliation(s)
- Namik Kaya
- College of Dentistry, The Ohio State University, 305 West 12th Ave., Columbus, OH 43210, USA
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Fiebich BL, Akundi RS, Seidel M, Geyer V, Haus U, Müller W, Stratz T, Candelario-Jalil E. Expression of 5-HT3A receptors in cells of the immune system. Scand J Rheumatol Suppl 2004; 119:9-11. [PMID: 15515405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
There is evidence from both human and animal research that 5-hydroxytryptamine3 (5-HT3) receptor antagonists, particularly tropisetron, exert analgesic and antiinflammatory effects. However, the underlying mechanisms of these effects including the expression of 5-HT3 receptors in cells of the immune system have not yet been investigated in detail. Therefore, we investigated the expression of the 5-HT3A receptor in primary human monocytes, chondrocytes, T-cells, dendritic cells, and synovial tissue. We found that 5-HT3A receptors are expressed in monocytes, chondrocytes, T-cells, and synovial tissue but not in dendritic cells. Our data show that 5-HT3A receptors are widely expressed in cells of the immune system and that they might play an important role in inflammatory events and in the observed antiphlogistic effects of 5-HT3 receptor antagonists.
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Affiliation(s)
- B L Fiebich
- Department of Psychiatry and Psychotherapy, University of Freiburg Medical School, Germany.
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14
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Mössner R, Schmitt A, Hennig T, Benninghoff J, Gerlach M, Riederer P, Deckert J, Lesch KP. Quantitation of 5HT3 receptors in forebrain of serotonin transporter deficient mice. J Neural Transm (Vienna) 2004; 111:27-35. [PMID: 14714213 DOI: 10.1007/s00702-003-0074-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2003] [Indexed: 11/25/2022]
Abstract
Mice deficient in the serotonin transporter (5HTT) display highly elevated extracellular 5HT levels. 5HT exerts ist effects via at least fourteen different cloned 5HT receptors located pre- and postsynaptically. In contrast to the other 5HT receptors, the 5HT3 receptor is a ionotropic receptor with ligand-gated cation channel function. Since G-protein-coupled 5HT receptors show extensive adaptive changes in 5HTT-deficient mice, we investigated whether 5HT3 receptors are also altered in these mice. Using quantitative autoradiography, we found that 5HT3 receptors are upregulated in frontal cortex (+46%), parietal cortex (+42%), and in stratum oriens of the CA3 region of the hippocampus (+18%) of 5HTT knockout mice. Changes in 5HT3 receptor mRNA expression, as determined by quantitative in situ hybridisation, were less pronounced. The adaptive changes of 5HT3 receptor expression constitute a part of the complex regulatory pattern of 5HT receptors in 5HTT knockout mice.
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Affiliation(s)
- R Mössner
- Department of Psychiatry and Psychotherapy, University of Wuerzburg, Germany.
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15
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Abstract
We describe the functional properties of a nicotinic alpha9/serotonin subtype 3A (5HT3A) chimeric receptor expressed in Xenopus laevis oocytes. The chimera preserved ligand-binding properties of alpha9 and channel properties of 5HT3A. Thus, it responded to acetylcholine in a concentration-dependent manner with an EC50 of 70 microM but not to serotonin. It was blocked by methyllycaconitine, strychnine, atropine and nicotine, with the same rank order of potency as alpha9 receptors. The current-voltage relationship of currents through the alpha9/5HT3A chimera was similar to that of the 5HT3A receptors. These results are an evidence of functional coupling between the ligand-binding and the channel domains of the chimeric receptor.
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Affiliation(s)
- Miguel Verbitsky
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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16
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Morales M, Wang SD, Diaz-Ruiz O, Jho DHJ. Cannabinoid CB1 receptor and serotonin 3 receptor subunit A (5-HT3A) are co-expressed in GABA neurons in the rat telencephalon. J Comp Neurol 2003; 468:205-16. [PMID: 14648680 DOI: 10.1002/cne.10968] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Among all described serotonin (5-HT) receptors in mammals, the type three (5-HT3) is the only ligand-gated ion channel receptor for serotonin. By using double in situ hybridization histochemistry, we found co-expression of the functional 5-HT3A subunit of the 5-HT3 receptor and the central CB1 cannabinoid receptor in neurons of the rat telencephalon. Double-labeled 5-HT3A/CB1 neurons were found in the anterior olfactory nucleus, superficial and deep layers of the cortex, hippocampal formation (hippocampus, dentate gyrus, subiculum, and entorhinal cortex) and amygdala. Analysis of the proportion of neurons co-expressing 5-HT3A and CB1 receptors in the cortex and amygdala showed that, depending on the brain region, 37-53% of all neurons expressing the 5-HT3A subunit also expressed CB1 transcripts; 16-72% of the total population of neurons expressing CB1 mRNA co-expressed the 5-HT3A subunit. By using a combination of double in situ hybridization and immunohistochemistry, we demonstrated that 5-HT3A/CB1-expressing neurons contained the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). These results imply that in distinct regions of the telencephalon, GABA neurons that react to cannabinoids may also be responsive to serotonin through 5-HT3 receptors. Cellular coexistence of 5-HT3A and CB1 transcripts in interneurons of the cortex, hippocampal formation, and amygdala suggest possible interactions between the cannabinoid and serotonergic systems at the level of GABA neurotransmission in brain areas involved in cognition, memory, and emotion.
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MESH Headings
- Animals
- Cannabinoids/analysis
- Cannabinoids/biosynthesis
- Cannabinoids/genetics
- Gene Expression Regulation/physiology
- Male
- Neurons/chemistry
- Neurons/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/analysis
- Receptor, Cannabinoid, CB1/biosynthesis
- Receptor, Cannabinoid, CB1/genetics
- Receptors, Serotonin, 5-HT3/analysis
- Receptors, Serotonin, 5-HT3/biosynthesis
- Receptors, Serotonin, 5-HT3/genetics
- Telencephalon/chemistry
- Telencephalon/metabolism
- gamma-Aminobutyric Acid/analysis
- gamma-Aminobutyric Acid/biosynthesis
- gamma-Aminobutyric Acid/genetics
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Affiliation(s)
- Marisela Morales
- National Institute on Drug Abuse, Intramural Research Program, Cellular Neurophysiology, Baltimore, Maryland 21224, USA.
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