101
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Role of glycosphingolipids in the function of human serotonin1A
receptors. J Neurochem 2012; 123:716-24. [DOI: 10.1111/jnc.12008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 09/02/2012] [Accepted: 09/04/2012] [Indexed: 11/26/2022]
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102
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Rodríguez JJ, Noristani HN, Verkhratsky A. The serotonergic system in ageing and Alzheimer's disease. Prog Neurobiol 2012; 99:15-41. [DOI: 10.1016/j.pneurobio.2012.06.010] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 05/24/2012] [Accepted: 06/22/2012] [Indexed: 01/11/2023]
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103
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Louie AS, Harrington LE, Valliant JF. The preparation and characterization of functionalized carboranes and Re/Tc-metallocarboranes as platforms for developing molecular imaging probes: Structural and cage isomerism studies. Inorganica Chim Acta 2012. [DOI: 10.1016/j.ica.2012.03.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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104
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Samadi Rad B, Ghasemi A, Seifi M, Samadikuchaksaraei A, Baybordi F, Danaei N. Serotonin 1A receptor genetic variations, suicide, and life events in the Iranian population. Psychiatry Clin Neurosci 2012; 66:337-43. [PMID: 22624739 DOI: 10.1111/j.1440-1819.2012.02333.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM The association of serotonin 1A receptor (5-HTR1A) gene polymorphisms with suicidal behavior has been reported in several previous studies, but the results have been inconsistent, which might be due to ethnic differences. The aim of the present study was therefore to investigate the association between polymorphisms -1019C>G, 47C>T (Pro16Leu) and 815G>A (Gly272Asp) and suicidal behavior, taking into account age, gender, and the presence of stressful life and loss events in 1 year prior to suicide. METHODS A total of 191 suicide victims and 218 healthy control subjects were included in the present study. 5-HT1RA gene polymorphisms were determined on polymerase chain reaction-restriction fragment length polymorphism. RESULTS The distribution of -1019C>G genotypes was significantly different in suicide victims and healthy controls (P = 0.002), and the GG genotype was associated with a significantly higher number of more stressful life and loss events in the suicide victims (P = 0.017, P = 0.037, respectively). The distribution of 47C>T (Pro16Leu) and 815G>A (Gly272Asp) genotypes was not significantly different in the suicide victims and control subjects (P > 0.05). Moreover, these genotypes were not associated with stressful life and loss events (P > 0.05). CONCLUSION The frequency of the -1019G allele in the 5-HTR1A gene was higher in suicide victims (with stressful life events) as compared with the control group. In contrast, neither 47C>T (Pro16Leu) nor 815G>A (Gly272Asp) polymorphisms were related with suicide and stressful life events.
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Affiliation(s)
- Bahram Samadi Rad
- Research Center of Iranian Legal Medicine Organization, Tehran, Iran
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105
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Sahu SK, Saxena R, Chattopadhyay A. Cholesterol depletion modulates detergent resistant fraction of human serotonin(1A) receptors. Mol Membr Biol 2012; 29:290-8. [PMID: 22594670 DOI: 10.3109/09687688.2012.688147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Insolubility of membrane components in non-ionic detergents such as Triton X-100 at low temperature is a widely used biochemical criterion to identify, isolate and characterize membrane domains. In this work, we monitored the detergent insolubility of the serotonin(1A) receptor in CHO cell membranes and its modulation by membrane cholesterol. The serotonin(1A) receptor is an important member of the G-protein coupled receptor family. It is implicated in the generation and modulation of various cognitive, behavioral and developmental functions and serves as a drug target. Our results show that a significant fraction (∼28%) of the serotonin(1A) receptor resides in detergent-resistant membranes (DRMs). Interestingly, the fraction of the serotonin(1A) receptor in DRMs exhibits a reduction upon membrane cholesterol depletion. In addition, we show that contents of DRM markers such as flotillin-1, caveolin-1 and GM₁ are altered in DRMs upon cholesterol depletion. These results assume significance since the function of the serotonin(1A) receptor has previously been shown to be affected by membrane lipids, specifically cholesterol. Our results are relevant in the context of membrane organization of the serotonin(1A) receptor in particular, and G-protein coupled receptors in general.
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Affiliation(s)
- Santosh Kumar Sahu
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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106
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The 5HT1a receptor agonist 8-Oh DPAT induces protection from lipofuscin accumulation and oxidative stress in the retinal pigment epithelium. PLoS One 2012; 7:e34468. [PMID: 22509307 PMCID: PMC3317995 DOI: 10.1371/journal.pone.0034468] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Accepted: 03/02/2012] [Indexed: 12/14/2022] Open
Abstract
Age-related macular degeneration (AMD), a major cause of blindness in the elderly, is associated with oxidative stress, lipofuscin accumulation and retinal degeneration. The aim of this study was to determine if a 5-HT(1A) receptor agonist can reduce lipofuscin accumulation, reduce oxidative damage and prevent retinal cell loss both in vitro and in vivo. Autophagy-derived and photoreceptor outer segment (POS)-derived lipofuscin formation was assessed using FACS analysis and confocal microscopy in cultured retinal pigment epithelial (RPE) cells in the presence or absence of the 5-HT(1A) receptor agonist, 8-OH DPAT. 8-OH DPAT treatment resulted in a dose-dependent reduction in both autophagy- and POS-derived lipofuscin compared to control. Reduction in autophagy-induced lipofuscin was sustained for 4 weeks following removal of the drug. The ability of 8-OH DPAT to reduce oxidative damage following exposure to 200 µM H(2)O(2) was assessed. 8-OH DPAT reduced superoxide generation and increased mitochondrial superoxide dismutase (MnSOD) levels and the ratio of reduced glutathione to the oxidized form of glutathione in H(2)O(2)-treated cells compared to controls and protected against H(2)O(2)-initiated lipid peroxidation, nitrotyrosine levels and mitochondrial damage. SOD2 knockdown mice, which have an AMD-like phenotype, received daily subcutaneous injections of either saline, 0.5 or 5.0 mg/kg 8-OH DPAT and were evaluated at monthly intervals. Systemic administration of 8-OH DPAT improved the electroretinogram response in SOD2 knockdown eyes of mice compared to knockdown eyes receiving vehicle control. There was a significant increase in the ONL thickness in mice treated with 8-OH DPAT at 4 months past the time of MnSOD knockdown compared to untreated controls together with a 60% reduction in RPE lipofuscin. The data indicate that 5-HT(1A) agonists can reduce lipofuscin accumulation and protect the retina from oxidative damage and mitochondrial dysfunction. 5-HT(1A) receptor agonists may have potential as therapeutic agents in the treatment of retinal degenerative disease.
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107
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Removal of sphingomyelin headgroup inhibits the ligand binding function of hippocampal serotonin1A receptors. Biochem Biophys Res Commun 2012; 419:321-5. [DOI: 10.1016/j.bbrc.2012.02.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 02/03/2012] [Indexed: 11/23/2022]
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108
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Chattopadhyay A, Paila YD, Shrivastava S, Tiwari S, Singh P, Fantini J. Sphingolipid-Binding Domain in the Serotonin1A Receptor. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 749:279-93. [DOI: 10.1007/978-1-4614-3381-1_19] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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109
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Renner U, Zeug A, Woehler A, Niebert M, Dityatev A, Dityateva G, Gorinski N, Guseva D, Abdel-Galil D, Fröhlich M, Döring F, Wischmeyer E, Richter DW, Neher E, Ponimaskin EG. Heterodimerization of serotonin receptors 5-HT1A and 5-HT7 differentially regulates receptor signalling and trafficking. J Cell Sci 2012; 125:2486-99. [DOI: 10.1242/jcs.101337] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Serotonin receptors 5-HT1A and 5-HT7 are highly co-expressed in brain regions implicated in depression. However, their functional interaction has not been established. In the present study we show that 5-HT1A and 5-HT7 receptors form heterodimers both in vitro and in vivo. Foerster resonance energy transfer-based assays revealed that, in addition to heterodimers, homodimers composed either by 5-HT1A or 5-HT7 receptors together with monomers co-exist in cells. The highest affinity to form the complex was obtained for the 5-HT7-5-HT7 homodimers, followed by the 5-HT7-5-HT1A heterodimers and 5-HT1A-5-HT1A homodimers. Functionally, heterodimerization decreases 5-HT1A receptor-mediated activation of Gi-protein without affecting 5-HT7 receptor-mediated signalling. Moreover, heterodimerization markedly decreases the ability of the 5-HT1A receptor to activate G-protein gated inwardly rectifying potassium channels in a heterologous system. The inhibitory effect on such channels was also preserved in hippocampal neurons, demonstrating a physiological relevance of heteromerization in vivo. In addition, heterodimerization is critically involved in initiation of the serotonin-mediated 5-HT1A receptor internalization and also enhances the ability of the 5-HT1A receptor to activate the mitogen-activated protein kinases. Finally, we found that production of 5-HT7 receptors in hippocampus continuously decreases during postnatal development, indicating that the relative concentration of 5-HT1A-5-HT7 heterodimers and, consequently, their functional importance undergoes pronounced developmental changes.
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110
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Lutz PE, Pradhan AA, Goeldner C, Kieffer BL. Sequential and opposing alterations of 5-HT(1A) receptor function during withdrawal from chronic morphine. Eur Neuropsychopharmacol 2011; 21:835-40. [PMID: 21402471 PMCID: PMC3149735 DOI: 10.1016/j.euroneuro.2011.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 02/03/2011] [Accepted: 02/10/2011] [Indexed: 12/15/2022]
Abstract
Addiction is a brain chronic relapsing disorder associated with emotional distress. The serotonergic system and especially the 5-HT(1A) receptor crucially regulate emotional behaviors both in humans and rodents. Using [(35)S]GTPγS autoradiography in mice, we show that 5-HT(1A) receptor function is enhanced by chronic morphine treatment in the medial prefrontal cortex, and decreased in dorsal raphe nucleus one week later, two regions involved in emotional processing. These molecular adaptations could contribute to the development of emotional disorders experienced by former opiate addicts.
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Affiliation(s)
- Pierre-Eric Lutz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
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111
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Abstract
Patient phenotypes in pharmacological pain treatment varies between individuals, which could be partly assigned to their genotypes regarding the targets of classical analgesics (OPRM1, PTGS2) or associated signalling pathways (KCNJ6). Translational and genetic research have identified new targets, for which new analgesics are being developed. This addresses voltage-gated sodium, calcium and potassium channels, for which SCN9A, CACNA1B, KCNQ2 and KCNQ3, respectively, are primary gene candidates because they code for the subunits of the respective channels targeted by analgesics currently in clinical development. Mutations in voltage gated transient receptor potential (TRPV) channels are known from genetic pain research and may modulate the effects of analgesics under development targeting TRPV1 or TRPV3. To this add ligand-gated ion channels including nicotinic acetylcholine receptors, ionotropic glutamate-gated receptors and ATP-gated purinergic P2X receptors with most important subunits coded by CHRNA4, GRIN2B and P2RX7. Among G protein coupled receptors, δ-opioid receptors (coded by OPRD1), cannabinoid receptors (CNR1 and CNR2), metabotropic glutamate receptors (mGluR5 coded by GRM5), bradykinin B(1) (BDKRB1) and 5-HT(1A) (HTR1A) receptors are targeted by new analgesic substances. Finally, nerve growth factor (NGFB), its tyrosine kinase receptor (NTRK1) and the fatty acid amide hydrolase (FAAH) have become targets of interest. For most of these genes, functional variants have been associated with neuro-psychiatric disorders and not yet with analgesia. However, research on the genetic modulation of pain has already identified variants in these genes, relative to pain, which may facilitate the pharmacogenetic assessments of new analgesics. The increased number of candidate pharmacogenetic modulators of analgesic actions may open opportunities for the broader clinical implementation of genotyping information.
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Affiliation(s)
- Jörn Lötsch
- pharmazentrum frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany.
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112
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Mao QQ, Huang Z, Ip SP, Xian YF, Che CT. Role of 5-HT(1A) and 5-HT(1B) receptors in the antidepressant-like effect of piperine in the forced swim test. Neurosci Lett 2011; 504:181-184. [PMID: 21964383 DOI: 10.1016/j.neulet.2011.09.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 09/14/2011] [Accepted: 09/16/2011] [Indexed: 11/29/2022]
Abstract
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.
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Affiliation(s)
- Qing-Qiu Mao
- School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; College of Pharmacy, Zhejiang Chinese Medicine University, Hangzhou, 310053 Zhejiang, China
| | - Zhen Huang
- College of Pharmacy, Zhejiang Chinese Medicine University, Hangzhou, 310053 Zhejiang, China
| | - Siu-Po Ip
- School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
| | - Yan-Fang Xian
- School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Chun-Tao Che
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL 60612, USA
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113
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Paila YD, Kombrabail M, Krishnamoorthy G, Chattopadhyay A. Oligomerization of the serotonin(1A) receptor in live cells: a time-resolved fluorescence anisotropy approach. J Phys Chem B 2011; 115:11439-47. [PMID: 21866959 DOI: 10.1021/jp201458h] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The serotonin(1A) receptor is a representative member of the G-protein coupled receptor (GPCR) superfamily and serves as an important target in the development of therapeutic agents for neuropsychiatric disorders. Oligomerization of GPCRs is an important contemporary issue since it is believed to be a crucial determinant for cellular signaling. In this work, we monitored the oligomerization status of the serotonin(1A) receptor tagged to enhanced yellow fluorescent protein (5-HT(1A)R-EYFP) in live cells utilizing time-resolved fluorescence anisotropy decay. We interpret the unresolved fast component of the observed anisotropy decay as fluorescence resonance energy transfer (FRET) between 5-HT(1A)R-EYFP molecules (homo-FRET). Homo-FRET enjoys certain advantages over hetero-FRET in the analysis of receptor oligomerization. Our results reveal the presence of constitutive oligomers of the serotonin(1A) receptor in live cells. We further show that the oligomerization status of the receptor is independent of ligand stimulation and sphingolipid depletion. Interestingly, acute (but not chronic) cholesterol depletion appears to enhance the oligomerization process. Importantly, our results are independent of receptor expression level, thereby ruling out complications arising due to high expression. These results have potential implications in future therapeutic strategies in pathophysiological conditions in which serotonin(1A) receptors are implicated.
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Affiliation(s)
- Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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114
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Singh P, Jafurulla M, Paila YD, Chattopadhyay A. Desmosterol replaces cholesterol for ligand binding function of the serotonin(1A) receptor in solubilized hippocampal membranes: support for nonannular binding sites for cholesterol? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2428-34. [PMID: 21763272 DOI: 10.1016/j.bbamem.2011.06.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 06/25/2011] [Accepted: 06/27/2011] [Indexed: 01/07/2023]
Abstract
The serotonin(1A) receptor is an important member of the G-protein coupled receptor family, and is involved in the generation and modulation of a variety of cognitive and behavioral functions. Solubilization of the hippocampal serotonin(1A) receptor by CHAPS is accompanied by loss of cholesterol that results in a reduction in specific agonist binding activity. Replenishment of cholesterol to solubilized membranes restores membrane cholesterol content and significantly recovers specific agonist binding. In order to test the stringency of cholesterol requirement, we solubilized native hippocampal membranes followed by replenishment with desmosterol. Desmosterol is the immediate biosynthetic precursor of cholesterol in the Bloch pathway differing only in a double bond at the 24th position. Our results show that replenishment with desmosterol restores ligand binding of serotonin(1A) receptors. This is consistent with earlier results showing that desmosterol can replace cholesterol in a large number of cases. However, these results appear to be contradictory to our earlier findings, performed by sterol manipulation utilizing methyl-β-cyclodextrin, in which we observed that replacing cholesterol with desmosterol is unable to restore specific ligand binding of the hippocampal serotonin(1A) receptor. We discuss the possible molecular mechanism, in terms of nonannular lipid binding sites around the receptor, giving rise to these differences.
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115
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Metabolic depletion of sphingolipids enhances the mobility of the human serotonin1A receptor. Biochem Biophys Res Commun 2011; 411:180-4. [DOI: 10.1016/j.bbrc.2011.06.127] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 06/18/2011] [Indexed: 12/22/2022]
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116
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Ganguly S, Clayton AHA, Chattopadhyay A. Organization of higher-order oligomers of the serotonin₁(A) receptor explored utilizing homo-FRET in live cells. Biophys J 2011; 100:361-8. [PMID: 21244832 DOI: 10.1016/j.bpj.2010.12.3692] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 11/16/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022] Open
Abstract
The serotonin₁(A) receptor is a representative member of the GPCR superfamily and serves as an important drug target. The possible role of GPCR oligomerization in receptor function is an active area of research. We monitored the oligomerization state of serotonin₁(A) receptors using homo-FRET and fluorescence lifetime measurements. Homo-FRET is estimated by a reduction in fluorescence anisotropy and provides a superior approach for exploring oligomerization. In addition, homo-FRET offers the possibility of detecting higher-order oligomers. On the basis of an observed increase in fluorescence anisotropy upon progressive photobleaching and analysis of the difference between the extrapolated anisotropy and the predicted anisotropy of an immobile monomer, we propose the presence of constitutive oligomers of the serotonin₁(A) receptor. To the best of our knowledge, these results constitute the first report of higher-order oligomers for the serotonin₁(A) receptor. We further show that cholesterol depletion and antagonist treatment result in a reduced population of higher-order oligomers. In contrast, agonist stimulation and destabilization of the actin cytoskeleton lead to an increased contribution from higher oligomers. These results provide novel insight into the oligomerization status of the serotonin₁(A) receptor that could enhance the ability to design better therapeutic strategies to combat diseases related to malfunctioning of GPCRs.
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Affiliation(s)
- Sourav Ganguly
- Centre for Cellular and Molecular Biology, Hyderabad, India
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117
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Ganguly S, Saxena R, Chattopadhyay A. Reorganization of the actin cytoskeleton upon G-protein coupled receptor signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1921-9. [PMID: 21501584 DOI: 10.1016/j.bbamem.2011.04.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 03/29/2011] [Accepted: 04/01/2011] [Indexed: 12/28/2022]
Abstract
The actin cytoskeleton is involved in a multitude of cellular responses besides providing structural support. While the role of the actin cytoskeleton in cellular processes such as trafficking and motility has been extensively studied, reorganization of the actin cytoskeleton upon signaling by G-protein coupled receptors (GPCRs) represents a relatively unexplored area. The G-protein coupled receptor superfamily is an important protein family in mammals, involved in signal transduction across membranes. G-protein coupled receptors act as major signaling hubs and drug targets. The serotonin(1A) receptor is a representative member of the G-protein coupled receptor superfamily and plays a crucial role in the generation and modulation of various cognitive, developmental and behavioral functions. In order to monitor the changes in the actin cytoskeleton upon serotonin(1A) receptor signaling in a quantitative manner, we developed an approach based on high magnification imaging of F-actin in cells, followed by image reconstruction. Our results suggest that the actin cytoskeleton is reorganized in response to serotonin(1A) receptor signaling. In addition, we show that reorganization of the actin cytoskeleton is strongly dependent on adenosine 3',5'-cyclic monophosphate level, and is mediated by the activation of protein kinase A. Our results are consistent with the possibility of a feedback mechanism involving the actin cytoskeleton, adenosine 3',5'-cyclic monophosphate level and the serotonin(1A) receptor.
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Affiliation(s)
- Sourav Ganguly
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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118
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Ganguly S, Clayton AHA, Chattopadhyay A. Fixation alters fluorescence lifetime and anisotropy of cells expressing EYFP-tagged serotonin1A receptor. Biochem Biophys Res Commun 2011; 405:234-7. [PMID: 21219865 DOI: 10.1016/j.bbrc.2011.01.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 01/05/2011] [Indexed: 11/15/2022]
Abstract
Fluorescence microscopic approaches represent powerful techniques to monitor molecular interactions in the cellular milieu. Measurements of fluorescence lifetime and anisotropy enjoy considerable popularity in this context. These measurements are often performed on live as well as fixed cells. We report here that formaldehyde-induced cell fixation introduces heterogeneities in the fluorescence emission of serotonin(1A) receptors tagged to enhanced yellow fluorescent protein, and alters fluorescence lifetime and anisotropy significantly. To the best of our knowledge, our results constitute the first report on the effect of formaldehyde fixation on fluorescence parameters of cellular proteins. We conclude that fluorescence parameters derived from fixed cells should be interpreted with caution.
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Affiliation(s)
- Sourav Ganguly
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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119
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Saxena R, Chattopadhyay A. Membrane organization and dynamics of the serotonin1A receptor in live cells. J Neurochem 2011; 116:726-33. [PMID: 21214564 DOI: 10.1111/j.1471-4159.2010.07037.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The G-protein coupled receptor (GPCR) superfamily is one of the largest classes of molecules involved in signal transduction across the plasma membrane. The serotonin(1A) receptor is a representative member of the GPCR superfamily and serves as an important target in the development of therapeutic agents for neuropsychiatric disorders such as anxiety and depression. In the context of the pharmacological relevance of the serotonin(1A) receptor, the membrane organization and dynamics of this receptor in the cellular environment assume relevance. We have highlighted results, obtained from fluorescence microscopy-based approaches, related to domain organization and dynamics of the serotonin(1A) receptor. A fraction of serotonin(1A) receptors displays detergent insolubility, monitored using green fluorescent protein, that increases upon depletion of membrane cholesterol. Fluorescence recovery after photobleaching measurements with varying bleach spot sizes show that lateral diffusion parameters of serotonin(1A) receptors in normal cells are consistent with models describing diffusion of molecules in a homogenous membrane. Interestingly, these characteristics are altered in cholesterol-depleted cells. Taken together, we conclude that the serotonin(1A) receptor exhibits dynamic confinement in the cellular plasma membranes. Progress in understanding GPCR organization and dynamics would result in better insight into our overall understanding of GPCR function in health and disease.
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Affiliation(s)
- Roopali Saxena
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, Andhra Pradesh, India
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120
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Jafurulla M, Tiwari S, Chattopadhyay A. Identification of cholesterol recognition amino acid consensus (CRAC) motif in G-protein coupled receptors. Biochem Biophys Res Commun 2010; 404:569-73. [PMID: 21146498 DOI: 10.1016/j.bbrc.2010.12.031] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 12/04/2010] [Indexed: 12/13/2022]
Abstract
G-protein coupled receptors (GPCRs) are the largest class of molecules involved in signal transduction across membranes, and represent major targets in the development of novel drug candidates in all clinical areas. Membrane cholesterol has been reported to have an important role in the function of a number of GPCRs. Several structural features of proteins, believed to result in preferential association with cholesterol, have been recognized. Cholesterol recognition/interaction amino acid consensus (CRAC) sequence represents such a motif. Many proteins that interact with cholesterol have been shown to contain the CRAC motif in their sequence. We report here the presence of CRAC motifs in three representative GPCRs, namely, rhodopsin, the β(2)-adrenergic receptor, and the serotonin(1A) receptor. Interestingly, the function of these GPCRs has been previously shown to be dependent on membrane cholesterol. The presence of CRAC motifs in GPCRs indicates that interaction of cholesterol with GPCRs could be specific in nature. Further analysis shows that CRAC motifs are inherent characteristic features of the serotonin(1A) receptor and are conserved over natural evolution. These results constitute the first report of the presence of CRAC motifs in GPCRs and provide novel insight in the molecular nature of GPCR-cholesterol interaction.
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Affiliation(s)
- Md Jafurulla
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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121
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Ohno Y. Therapeutic role of 5-HT1A receptors in the treatment of schizophrenia and Parkinson's disease. CNS Neurosci Ther 2010; 17:58-65. [PMID: 21091640 DOI: 10.1111/j.1755-5949.2010.00211.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
5-HT(1A) receptors have long been implicated in the pathogenesis and treatment of anxiety and depressive disorders. Recently, several lines of studies have revealed new insights into the therapeutic role of 5-HT(1A) receptors in treating schizophrenia and Parkinson's disease. Specifically, 5-HT(1A) receptors seem to be a promising target for alleviating antipsychotic-induced extrapyramidal side effects (EPS) and cognitive/affective disorders in schizophrenia. In the treatment of patients with Parkinson's disease, 5-HT(1A) agonists are expected to improve not only affective symptoms (e.g., anxiety and depression), but also the core parkinsonian symptoms as well as antiparkinsonian agents-induced side effects (e.g., L-DOPA-induced dyskinesia). Here, the therapeutic mechanisms mediated by 5-HT(1A) receptors in schizophrenia and Parkinson's disease are reviewed. This evidence should encourage discovery of new 5-HT(1A) ligands, which can resolve the unmet clinical needs in the current therapy.
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Affiliation(s)
- Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka, Japan.
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122
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Paila YD, Tiwari S, Sengupta D, Chattopadhyay A. Molecular modeling of the human serotonin(1A) receptor: role of membrane cholesterol in ligand binding of the receptor. MOLECULAR BIOSYSTEMS 2010; 7:224-34. [PMID: 20967314 DOI: 10.1039/c0mb00148a] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Serotonin(1A) receptors are important neurotransmitter receptors and belong to the superfamily of G-protein coupled receptors (GPCRs). Although it is an important drug target, the crystal structure of the serotonin(1A) receptor has not been solved yet. Earlier homology models of the serotonin(1A) receptor were generated using rhodopsin as a template. We have used two recent crystal structures of the human β(2)-adrenergic receptor, one of which shows specific cholesterol binding site(s), as templates to model the human serotonin(1A) receptor. Since the sequence similarity between the serotonin(1A) receptor and β(2)-adrenergic receptor is considerably higher than the similarity between the serotonin(1A) receptor and rhodopsin, our model is more reliable. Based on these templates, we generated models of the serotonin(1A) receptor in the absence and presence of cholesterol. The receptor model appears more compact in the presence of cholesterol. We validated the stability of 'compactness' using coarse-grain MD simulation. Importantly, all ligands exhibit higher binding energies when docked to the receptor in the presence of cholesterol, thereby implying that membrane cholesterol facilitates ligand binding to the serotonin(1A) receptor. To the best of our knowledge, this is one of the first reports in which lipid-specific receptor conformations have been modeled by homology modeling.
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Affiliation(s)
- Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India.
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123
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Lacivita E, Masotti AC, Jafurulla M, Saxena R, Rangaraj N, Chattopadhyay A, Colabufo NA, Berardi F, Perrone R, Leopoldo M. Identification of a red-emitting fluorescent ligand for in vitro visualization of human serotonin 5-HT(1A) receptors. Bioorg Med Chem Lett 2010; 20:6628-32. [PMID: 20888762 DOI: 10.1016/j.bmcl.2010.09.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 09/03/2010] [Accepted: 09/04/2010] [Indexed: 01/24/2023]
Abstract
The 5-HT(1A) receptor subtype is the most thoroughly studied serotonin receptor subtype. We report here the design, synthesis and characterization of two new fluorescent ligands for the 5-HT(1A) receptor. The new 1-arylpiperazine-based red-emitting fluorescent compound 6 displayed good binding affinity at the 5-HT(1A) receptor (K(i)=35 nM) and was able to label specifically the human 5-HT(1A) receptor stably expressed in CHO cells visualized using confocal laser scanning microscopy.
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Affiliation(s)
- Enza Lacivita
- Università degli Studi di Bari A. Moro, Dipartimento Farmaco-Chimico, via Orabona, 4, 70125 Bari, Italy
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124
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Paila YD, Jindal E, Goswami SK, Chattopadhyay A. Cholesterol depletion enhances adrenergic signaling in cardiac myocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:461-5. [PMID: 20851100 DOI: 10.1016/j.bbamem.2010.09.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 09/08/2010] [Accepted: 09/08/2010] [Indexed: 10/19/2022]
Abstract
Cardiac myocytes endogenously express α and β adrenergic receptors, prototypes of the G-protein coupled receptor superfamily. Depending upon the dose of norepinephrine (agonist) exposure, hypertrophy and apoptosis are initiated by differential induction of two discrete constituents of the transcription factor AP-1, i.e., FosB and Fra-1. We explored differential adrenergic signaling as a paradigm for understanding how cholesterol dictates cells to choose hypertrophy or apoptosis. For this, we used fosB and fra-1 promoter-reporter constructs for monitoring adrenergic signaling. We show that cholesterol depletion enhances norepinephrine-mediated signaling in cardiac myocytes. Importantly, this increased signaling is reduced to original level upon cholesterol replenishment. We used specific ligands for α and β adrenergic receptors and show that the enhanced signaling upon cholesterol depletion is a combined effect of both α and β adrenergic receptors. These results constitute the first report demonstrating the effect of cholesterol on adrenergic signaling using a direct end-point gene expression.
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Affiliation(s)
- Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research Uppal Road, Hyderabad 500 007, India
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125
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Ganguly S, Chattopadhyay A. Cholesterol depletion mimics the effect of cytoskeletal destabilization on membrane dynamics of the serotonin1A receptor: A zFCS study. Biophys J 2010; 99:1397-407. [PMID: 20816051 PMCID: PMC2931730 DOI: 10.1016/j.bpj.2010.06.031] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 06/14/2010] [Accepted: 06/15/2010] [Indexed: 01/23/2023] Open
Abstract
Single-point fluorescence correlation spectroscopy (FCS) of membrane-bound molecules suffers from a number of limitations leading to inaccurate estimation of diffusion parameters. To overcome such problems and with the overall goal of addressing membrane heterogeneities, we performed z-scan FCS (zFCS) of the serotonin(1A) receptor. We analyzed the results according to FCS diffusion laws that provide information on the organization of the diffusing species. Analysis of our results shows that the diffusion coefficients of the receptor and a fluorescently labeled phospholipid are similar when probed at length scales approximately 210 nm. We discuss the significance of the spatiotemporal evolution of dynamics of membrane-bound molecules in the overall context of membrane domains and heterogeneity. Importantly, our results show that the serotonin(1A) receptor exhibits confinement in cell membranes, possibly due to interaction with the actin cytoskeleton. Surprisingly, depletion of membrane cholesterol appears to reduce receptor confinement in a manner similar to that observed in the case of cytoskeletal destabilization, implying possible changes in the actin cytoskeleton induced upon cholesterol depletion. These results constitute the first report on G-protein-coupled receptor dynamics utilizing a combination of zFCS and the FCS diffusion laws, and present a convenient approach to explore cell membrane heterogeneity at the submicron level.
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Affiliation(s)
| | - Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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126
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Role of cortical and striatal 5-HT1A receptors in alleviating antipsychotic-induced extrapyramidal disorders. Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:877-81. [PMID: 20398719 DOI: 10.1016/j.pnpbp.2010.04.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/07/2010] [Accepted: 04/07/2010] [Indexed: 11/22/2022]
Abstract
Previous studies have revealed that 5-HT(1A) agonists ameliorate antipsychotic-induced extrapyramidal symptoms (EPS) through postsynaptic 5-HT(1A) receptors. Here, we conducted an intracerebral microinjection study of (+/-)-8-hydroxy-2-(di-n-propylamino)-tetralin ((+/-)8-OH-DPAT) to determine the action site of the 5-HT(1A) agonist in alleviating EPS. Bilateral microinjection of(+/-)8-OH-DPAT (5 microg/1microL per side) either into the primary motor cortex (MC) or the dorsolateral striatum (dlST) significantly attenuated haloperidol-induced catalepsy in rats. The anticataleptic action of (+/-)8-OH-DPAT was more prominent with the MC injection than with the dlST injection. WAY-100135 (a selective 5-HT(1A) antagonist) completely antagonized the reversal of haloperidol-induced catalepsy both by intracortical and intrastriatal (+/-)8-OH-DPAT. Furthermore, lesioning of dopamine neurons with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (30 mg/kg/day, i.p., for 4 days) did not alter the anti-EPS actions of (+/-)8-OH-DPAT in a mouse pole test. The present results strongly suggest that 5-HT(1A) agonist alleviates antipsychotic-induced EPS by activating postsynaptic 5-HT(1A) receptors in the MC and dlST, probably through non-dopaminergic mechanisms.
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127
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Shrivastava S, Pucadyil TJ, Paila YD, Ganguly S, Chattopadhyay A. Chronic Cholesterol Depletion Using Statin Impairs the Function and Dynamics of Human Serotonin1A Receptors. Biochemistry 2010; 49:5426-35. [DOI: 10.1021/bi100276b] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sandeep Shrivastava
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
| | - Thomas J. Pucadyil
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
| | - Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
| | - Sourav Ganguly
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
| | - Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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128
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Paila YD, Ganguly S, Chattopadhyay A. Metabolic Depletion of Sphingolipids Impairs Ligand Binding and Signaling of Human Serotonin1A Receptors. Biochemistry 2010; 49:2389-97. [DOI: 10.1021/bi1001536] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
| | - Sourav Ganguly
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
| | - Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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129
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Pharmacophore-based 3D QSAR studies on a series of high affinity 5-HT1A receptor ligands. Eur J Med Chem 2010; 45:1508-14. [PMID: 20133028 DOI: 10.1016/j.ejmech.2009.12.059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 12/18/2009] [Indexed: 11/21/2022]
Abstract
5-HT(1A) receptor antagonists have been employed to treat depression, but the lack of structural information on this receptor hampers the design of specific and selective ligands. In this study, we have performed CoMFA studies on a training set of arylpiperazines (high affinity 5-HT(1A) receptor ligands) and to produce an effective alignment of the data set, a pharmacophore model was produced using Galahad. A statistically significant model was obtained, indicating a good internal consistency and predictive ability for untested compounds. The information gathered from our receptor-independent pharmacophore hypothesis is in good agreement with results from independent studies using different approaches. Therefore, this work provides important insights on the chemical and structural basis involved in the molecular recognition of these compounds.
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130
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Paila YD, Chattopadhyay A. Membrane cholesterol in the function and organization of G-protein coupled receptors. Subcell Biochem 2010; 51:439-66. [PMID: 20213554 DOI: 10.1007/978-90-481-8622-8_16] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cholesterol is an essential component of higher eukaryotic membranes and plays a crucial role in membrane organization, dynamics and function. The G-protein coupled receptors (GPCRs) are the largest class of molecules involved in signal transduction across membranes, and represent major targets in the development of novel drug candidates in all clinical areas. Membrane cholesterol has been reported to have a modulatory role in the function of a number of GPCRs. Two possible mechanisms have been previously suggested by which membrane cholesterol could influence the structure and function of GPCRs (i) through a direct/specific interaction with GPCRs, or (ii) through an indirect way by altering membrane physical properties in which the receptor is embedded, or due to a combination of both. Recently reported crystal structures of GPCRs have shown structural evidence of cholesterol binding sites. Against this backdrop, we recently proposed a novel mechanism by which membrane cholesterol could affect structure and function of GPCRs. According to our hypothesis, cholesterol binding sites in GPCRs could represent 'nonannular' binding sites. Interestingly, previous work from our laboratory has demonstrated that membrane cholesterol is required for the function of the serotonin(1A) receptor (a representative GPCR), which could be due to specific interaction of the receptor with cholesterol. Based on these results, we envisage that there could be specific/nonannular cholesterol binding site(s) in the serotonin(1A) receptor. We have analyzed putative cholesterol binding sites from protein databases in the serotonin(1A) receptor. Our analysis shows that cholesterol binding sites are inherent characteristic features of serotonin(1A) receptors and are conserved through natural evolution. Progress in deciphering molecular details of the GPCR-cholesterol interaction in the membrane would lead to better insight into our overall understanding of GPCR function in health and disease, thereby enhancing our ability to design better therapeutic strategies to combat diseases related to malfunctioning of GPCRs.
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Affiliation(s)
- Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, 500 007, India
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131
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Ohno Y, Sofue N, Imaoku T, Morishita E, Kumafuji K, Sasa M, Serikawa T. Serotonergic Modulation of Absence-Like Seizures in Groggy Rats: a Novel Rat Model of Absence Epilepsy. J Pharmacol Sci 2010; 114:99-105. [DOI: 10.1254/jphs.10156fp] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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132
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Lacivita E, Leopoldo M, Masotti AC, Inglese C, Berardi F, Perrone R, Ganguly S, Jafurulla M, Chattopadhyay A. Synthesis and characterization of environment-sensitive fluorescent ligands for human 5-HT1A receptors with 1-arylpiperazine structure. J Med Chem 2009; 52:7892-6. [PMID: 19705871 DOI: 10.1021/jm900706d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of "long-chain" 1-(2-methoxyphenyl)piperazine derivatives containing an environment-sensitive fluorescent moiety (4-amino-1,8-naphthalimide, 4-dimethylaminophthalimide, dansyl) was synthesized. The compounds displayed very high to moderate 5-HT(1A) receptor affinity and good fluorescence properties. 6-Amino-2-[5-[4-(2-methoxyphenyl)-1-piperazinyl]pentyl]-1H-benz[de]isoquinoline-1,3(2H)-dione (4) combined very high 5-HT(1A) receptor affinity (K(i) = 0.67 nM), high fluorescence emission in CHCl(3), and undetectable fluorescence emission in aqueous solution. It was evaluated for its ability to visualize 5-HT(1A) receptors overexpressed in CHO cells by fluorescence microscopy.
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Affiliation(s)
- Enza Lacivita
- Dipartimento Farmaco-Chimico, Universita degli Studi di Bari, via Orabona 4, 70125 Bari, Italy
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133
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Prasad R, Paila YD, Jafurulla M, Chattopadhyay A. Membrane cholesterol depletion from live cells enhances the function of human serotonin1A receptors. Biochem Biophys Res Commun 2009; 389:333-7. [DOI: 10.1016/j.bbrc.2009.08.148] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Accepted: 08/25/2009] [Indexed: 10/20/2022]
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134
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Ganguly S, Singh P, Manoharlal R, Prasad R, Chattopadhyay A. Differential dynamics of membrane proteins in yeast. Biochem Biophys Res Commun 2009; 387:661-5. [DOI: 10.1016/j.bbrc.2009.07.054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 07/13/2009] [Indexed: 10/20/2022]
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135
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Prasad R, Paila YD, Chattopadhyay A. Membrane cholesterol depletion enhances ligand binding function of human serotonin1A receptors in neuronal cells. Biochem Biophys Res Commun 2009; 390:93-6. [PMID: 19781522 DOI: 10.1016/j.bbrc.2009.09.072] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Accepted: 09/16/2009] [Indexed: 12/16/2022]
Abstract
Membrane lipid composition of cells in the nervous system is unique and displays remarkable diversity. Cholesterol metabolism and homeostasis in the central nervous system and their role in neuronal function represent important determinants in neuropathogenesis. The serotonin(1A) receptor is an important member of the G-protein coupled receptor superfamily, and is involved in a variety of cognitive, behavioral, and developmental functions. We report here, for the first time, that the ligand binding function of human serotonin(1A) receptors exhibits an increase in membranes isolated from cholesterol-depleted neuronal cells. Our results gain pharmacological significance in view of the recently described structural evidence of specific cholesterol binding site(s) in GPCRs, and could be useful in designing better therapeutic strategies for neurodegenerative diseases associated with GPCRs.
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Affiliation(s)
- Rajesh Prasad
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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136
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Fantini J, Barrantes FJ. Sphingolipid/cholesterol regulation of neurotransmitter receptor conformation and function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2345-61. [PMID: 19733149 DOI: 10.1016/j.bbamem.2009.08.016] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2009] [Revised: 07/17/2009] [Accepted: 08/28/2009] [Indexed: 10/20/2022]
Abstract
Like all other monomeric or multimeric transmembrane proteins, receptors for neurotransmitters are surrounded by a shell of lipids which form an interfacial boundary between the protein and the bulk membrane. Among these lipids, cholesterol and sphingolipids have attracted much attention because of their well-known propensity to segregate into ordered platform domains commonly referred to as lipid rafts. In this review we present a critical analysis of the molecular mechanisms involved in the interaction of cholesterol/sphingolipids with neurotransmitter receptors, in particular acetylcholine and serotonin receptors, chosen as representative members of ligand-gated ion channels and G protein-coupled receptors. Cholesterol and sphingolipids interact with these receptors through typical binding sites located in both the transmembrane helices and the extracellular loops. By altering the conformation of the receptors ("chaperone-like" effect), these lipids can regulate neurotransmitter binding, signal transducing functions, and, in the case of multimeric receptors, subunit assembly and subsequent receptor trafficking to the cell surface. Several sphingolipids (especially gangliosides) also exhibit low/moderate affinity for neurotransmitters. We suggest that such lipids could facilitate (i) the attachment of neurotransmitters to the post-synaptic membrane and in some cases (ii) their subsequent delivery to specific protein receptors. Overall, various experimental approaches provide converging evidence that the biological functions of neurotransmitters and their receptors are highly dependent upon sphingolipids and cholesterol, which are active partners of synaptic transmission. Several decades of research have been necessary to untangle the skein of a complex network of molecular interactions between neurotransmitters, their receptors, cholesterol and sphingolipids. This sophisticated crosstalk between all four distinctive partners may allow a fine biochemical tuning of synaptic transmission.
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Affiliation(s)
- Jacques Fantini
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille (CRN2M), University of Aix-Marseille 2 and Aix-Marseille 3, CNRS UMR 6231, INRA USC 2027, Faculté des Sciences de St. Jérôme, Laboratoire des Interactions Moléculaires et Systèmes Membranaires, Marseille, France
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137
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Singh P, Saxena R, Paila YD, Jafurulla M, Chattopadhyay A. Differential effects of cholesterol and desmosterol on the ligand binding function of the hippocampal serotonin(1A) receptor: implications in desmosterolosis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2169-73. [PMID: 19616511 DOI: 10.1016/j.bbamem.2009.07.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 06/18/2009] [Accepted: 07/08/2009] [Indexed: 01/19/2023]
Abstract
Cholesterol is a unique molecule in terms of high level of in-built stringency, fine tuned by natural evolution for its ability to optimize physical properties of higher eukaryotic cell membranes in relation to biological functions. We previously demonstrated the requirement of membrane cholesterol in maintaining the ligand binding activity of the hippocampal serotonin(1A) receptor. In order to test the molecular stringency of the requirement of cholesterol, we depleted cholesterol from native hippocampal membranes followed by replenishment with desmosterol. Desmosterol is an immediate biosynthetic precursor of cholesterol in the Bloch pathway differing only in a double bond at the 24th position in the alkyl side chain. Our results show that replenishment with desmosterol does not restore ligand binding activity of the serotonin(1A) receptor although replenishment with cholesterol led to significant recovery of ligand binding. This is in spite of similar membrane organization (order) in these membranes, as monitored by fluorescence anisotropy measurements. The requirement for restoration of ligand binding activity therefore appears to be more stringent than the requirement for the recovery of overall membrane order. These novel results have potential implications in understanding the interaction of membrane lipids with this important neuronal receptor in diseases such as desmosterolosis.
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Affiliation(s)
- Pushpendra Singh
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad 500 007, India
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138
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Mukherjee S, Kalipatnapu S, Pucadyil TJ, Chattopadhyay A. Monitoring the organization and dynamics of bovine hippocampal membranes utilizing differentially localized fluorescent membrane probes. Mol Membr Biol 2009; 23:430-41. [PMID: 17060160 DOI: 10.1080/09687860600803223] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Previous work from our laboratory has established bovine hippocampal membranes as a convenient natural source for studying neuronal receptors such as the G-protein coupled serotonin1A receptor. In this paper, we have explored the organization and dynamics of bovine hippocampal membranes using environment-sensitive and differentially localized fluorescent probes NBD-PE and NBD-cholesterol, utilizing wavelength-selective and time-resolved fluorescence measurements. The NBD group in NBD-PE is localized at the membrane interface while in NBD-cholesterol it is localized deeper in the membrane. Our results show that native hippocampal membranes offer considerable motional restriction as evidenced from red edge excitation shift of NBD probes. However, this effect progressively decreases with increasing cholesterol depletion in the case of NBD-cholesterol, possibly indicating a reduction in membrane heterogeneity. In contrast, REES of NBD-PE in hippocampal membranes does not show any significant change upon cholesterol depletion indicating relative lack of sensitivity of the membrane interface to cholesterol depletion. These observations are supported by changes in fluorescence polarization with cholesterol depletion. Taken together, these results imply that the deeper hydrocarbon region of the hippocampal membrane is more sensitive to changes in membrane organization and dynamics due to cholesterol depletion than the interfacial region. The motional restriction in native membranes is maintained even in the absence of proteins. The fluorescence lifetimes of both the NBD probes show slight reduction upon cholesterol depletion indicating a change in micro-environmental polarity possibly due to water penetration. These results are relevant in understanding the complex organization of hippocampal membranes and could have possible functional implications.
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139
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Kalipatnapu S, Chattopadhyay A. Membrane organization of the human serotonin1Areceptor monitored by detergent insolubility using GFP fluorescence. Mol Membr Biol 2009; 22:539-47. [PMID: 16373325 DOI: 10.1080/09687860500421738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Insolubility in non-ionic detergents such as Triton X-100 at low temperature is a widely used biochemical criterion for characterization of membrane domains. In view of the emerging role of membrane organization in the function of G-protein coupled receptors, we have examined detergent insolubility of the 5-HT(1A) receptor in CHO cells using a novel GFP fluorescence approach developed by us. Using this approach, we have explored the membrane organization of the serotonin(1A) receptor tagged to enhanced yellow fluorescent protein (5-HT(1A)R-EYFP) stably expressed in CHO-K1 cells under conditions of varying detergent concentration, reduced membrane cholesterol and agonist stimulation. Our results show that a small yet significant fraction of the 5-HT(1A) receptor exhibits detergent insolubility, which increases upon depletion of membrane cholesterol. Stimulation of 5-HT(1A)R-EYFP by its endogenous ligand, serotonin, did not cause a significant change in the detergent insolubility of the receptor. Taken together, our results on detergent insolubility of 5-HT(1A)R-EYFP provide new insights into the membrane organization of the 5-HT(1A) receptor and could be relevant in the analysis of membrane organization of other G-protein coupled receptors.
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140
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Fonseca FV, Mecawi AS, Araujo IG, Almeida-Pereira G, Magalhães-Nunes AP, Badauê-Passos D, Reis LC. Role of the 5-HT1A somatodendritic autoreceptor in the dorsal raphe nucleus on salt satiety signaling in rats. Exp Neurol 2009; 217:353-60. [DOI: 10.1016/j.expneurol.2009.03.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 03/13/2009] [Accepted: 03/14/2009] [Indexed: 02/04/2023]
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141
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Suicide, stress and serotonin receptor 1A promoter polymorphism -1019C>G in Slovenian suicide victims. Eur Arch Psychiatry Clin Neurosci 2009; 259:234-8. [PMID: 19224112 DOI: 10.1007/s00406-008-0861-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 11/28/2008] [Indexed: 12/13/2022]
Abstract
Implication of serotonergic system in suicide and suicide attempts has been discussed for several years. One of the most abundant serotonin receptors in the mammalian brain is the receptor 1A (5-HT1A); studies of its polymorphisms and suicide have provided very inconsistent results so far. The suggestion that the G allele depresses HTR1A autoreceptor expression, and therefore reduces serotonergic neurotransmission that might predispose to depression and suicide, made the promoter polymorphism -1019C>G a very promising candidate gene. In our study we analyzed promoter polymorphism -1019C>G on 323 suicide victims and 190 controls (all of Slovenian origin), taking into account sex, suicide method, and in case of suicide victims also stressful life events. Differences in the distributions of genotype and allele frequencies were not statistically significant between suicide victims and control group, and the same was found for distributions according to sex and suicide method. For 62 suicide victims information about stressful life events in the month prior to the suicide and in childhood was provided. For analysis we combined CG/GG genotypes and compared them to the CC genotype. More stressful life events in the month prior to the suicide were reported for the subgroup with CC genotype (mean number of events = 2.53; SD = 1.50) in comparison to subgroup with CG/GG genotypes (mean number of events = 1.58; SD = 1.32; P < 0.05). However, subgroups of suicide victims with CC or CG/GG genotypes did not differ regarding numbers of reported stressful life events in childhood (P > 0.05). Our study provides no evidence for the implication of HTR1A promoter polymorphism in suicide in general, but it suggests further studies that would take into account the interconnected network of suicide completion, genetic background and stress, beside other risk factors.
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Shpakov AO. Structural functional characteristic of neuronal serotonin receptors and molecular mechanisms of their coupling with G-proteins. NEUROCHEM J+ 2009. [DOI: 10.1134/s1819712409010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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143
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Moulin-Sallanon M, Charnay Y, Ginovart N, Perret P, Lanfumey L, Hamon M, Hen R, Fagret D, Ibáñez V, Millet P. Acute and chronic effects of citalopram on 5-HT1A receptor-labeling by [18F]MPPF and -coupling to receptors-G proteins. Synapse 2009; 63:106-16. [PMID: 19016488 DOI: 10.1002/syn.20588] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Selective serotonin reuptake inhibitors take several weeks to produce their maximal therapeutic antidepressant effect. This delay has been attributed to the gradual desensitization of somatodendritic serotonin 5-HT(1A) autoreceptors. We evaluated adaptive changes of 5-HT(1A) receptors after acute and chronic citalopram challenges in rat. Small animal positron emission tomography trial and quantitative ex vivo autoradiography studies using [(18)F]MPPF were employed, as well as in vitro 8-OH-DPAT-stimulated [(35)S]-GTPgammaS binding assay. Additionally, 5-HT(1A) receptor knock-out mice were used to assess the specificity of [(18)F]MPPF. Acute treatment with citalopram did not alter [(18)F]MPPF binding in dorsal raphe nucleus (DR), frontal cortex, or hippocampus. The absence of [(18)F]MPPF binding in the brain of 5-HT(1A) knock-out mice demonstrates the specificity of MPPF for 5-HT(1A) receptor brain imaging, but the high affinity of [(18)F]MPPF compared to 5-HT suggests that it would only be displaced by dramatic increases in extracellular 5-HT. Chronic citalopram did not modify 5-HT(1A) receptor density in any of the brain regions studied. In addition, this treatment did not modify 8-OH-DPAT-stimulated [(35)S]-GTPgammaS binding in DR, although a significant increase was observed in frontal cortex and hippocampus. [(18)F]MPPF appears to be an efficient radioligand to quantify specifically 5-HT(1A) receptor density in brain imaging. The delayed therapeutic efficacy of citalopram did not appear to be linked to either a downregulation of 5-HT(1A) receptors or to a 5-HT(1A) receptor-G protein decoupling process in serotonergic neurons, but to increased functional sensitivity of postsynaptic 5-HT(1A) receptors.
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Briones-Aranda A, Castillo-Salazar M, Picazo O. Adrenalectomy modifies the hippocampal 5-HT1A receptors and the anxiolytic-like effect of 8-OH-DPAT in rats. Pharmacol Biochem Behav 2009; 92:182-9. [DOI: 10.1016/j.pbb.2008.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 11/15/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
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145
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Are specific nonannular cholesterol binding sites present in G-protein coupled receptors? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:295-302. [DOI: 10.1016/j.bbamem.2008.11.020] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 11/18/2008] [Accepted: 11/20/2008] [Indexed: 11/23/2022]
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146
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LeGreve TA, James III WH, Zwier TS. Solvent Effects on the Conformational Preferences of Serotonin: Serotonin−(H2O)n, n = 1,2. J Phys Chem A 2008; 113:399-410. [PMID: 19099446 DOI: 10.1021/jp807031y] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Tracy A. LeGreve
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084
| | | | - Timothy S. Zwier
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084
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Paila YD, Chattopadhyay A. The function of G-protein coupled receptors and membrane cholesterol: specific or general interaction? Glycoconj J 2008; 26:711-20. [DOI: 10.1007/s10719-008-9218-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 10/29/2008] [Accepted: 11/07/2008] [Indexed: 01/21/2023]
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148
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Quantitative trait locus analysis identifies rat genomic regions related to amphetamine-induced locomotion and Galpha(i3) levels in nucleus accumbens. Neuropsychopharmacology 2008; 33:2735-46. [PMID: 18216777 PMCID: PMC2818767 DOI: 10.1038/sj.npp.1301667] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Identification of the genetic factors that underlie stimulant responsiveness in animal models has significant implications for better understanding and treating stimulant addiction in humans. F(2) progeny derived from parental rat strains F344/NHsd and LEW/NHsd, which differ in responses to drugs of abuse, were used in quantitative trait locus (QTL) analyses to identify genomic regions associated with amphetamine-induced locomotion (AIL) and G-protein levels in the nucleus accumbens (NAc). The most robust QTLs were observed on chromosome 3 (maximal log ratio statistic score (LRS(max))=21.3) for AIL and on chromosome 2 (LRS(max)=22.0) for Galpha(i3). A 'suggestive' QTL (LRS(max)=12.5) was observed for AIL in a region of chromosome 2 that overlaps with the Galpha(i3) QTL. Novelty-induced locomotion (NIL) showed different QTL patterns from AIL, with the most robust QTL on chromosome 13 (LRS(max)=12.2). Specific unique and overlapping genomic regions influence AIL, NIL, and inhibitory G-protein levels in the NAc. These findings suggest that common genetic mechanisms influence certain biochemical and behavioral aspects of stimulant responsiveness.
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Jafurulla M, Pucadyil TJ, Chattopadhyay A. Effect of sphingomyelinase treatment on ligand binding activity of human serotonin1A receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2022-5. [DOI: 10.1016/j.bbamem.2008.07.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 07/07/2008] [Accepted: 07/09/2008] [Indexed: 01/24/2023]
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150
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Effect of capsaicin on ligand binding activity of the hippocampal serotonin1A receptor. Glycoconj J 2008; 26:733-8. [DOI: 10.1007/s10719-008-9185-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Revised: 08/20/2008] [Accepted: 08/26/2008] [Indexed: 11/26/2022]
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