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Strekalova T, Moskvin O, Jain AY, Gorbunov N, Gorlova A, Sadovnik D, Umriukhin A, Cespuglio R, Yu WS, Tse ACK, Kalueff AV, Lesch KP, Lim LW. Molecular signature of excessive female aggression: study of stressed mice with genetic inactivation of neuronal serotonin synthesis. J Neural Transm (Vienna) 2023; 130:1113-1132. [PMID: 37542675 PMCID: PMC10460733 DOI: 10.1007/s00702-023-02677-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/21/2023] [Indexed: 08/07/2023]
Abstract
Aggression is a complex social behavior, critically involving brain serotonin (5-HT) function. The neurobiology of female aggression remains elusive, while the incidence of its manifestations has been increasing. Yet, animal models of female aggression are scarce. We previously proposed a paradigm of female aggression in the context of gene x environment interaction where mice with partial genetic inactivation of tryptophan hydroxylase-2 (Tph2+/- mice), a key enzyme of neuronal 5-HT synthesis, are subjected to predation stress resulting in pathological aggression. Using deep sequencing and the EBSeq method, we studied the transcriptomic signature of excessive aggression in the prefrontal cortex of female Tph2+/- mice subjected to rat exposure stress and food deprivation. Challenged mutants, but not other groups, displayed marked aggressive behaviors. We found 26 genes with altered expression in the opposite direction between stressed groups of both Tph2 genotypes. We identified several molecular markers, including Dgkh, Arfgef3, Kcnh7, Grin2a, Tenm1 and Epha6, implicated in neurodevelopmental deficits and psychiatric conditions featuring impaired cognition and emotional dysregulation. Moreover, while 17 regulons, including several relevant to neural plasticity and function, were significantly altered in stressed mutants, no alteration in regulons was detected in stressed wildtype mice. An interplay of the uncovered pathways likely mediates partial Tph2 inactivation in interaction with severe stress experience, thus resulting in excessive female aggression.
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Affiliation(s)
- Tatyana Strekalova
- Division of Molecular Psychiatry, Center of Mental Health, University Hospital of Würzburg, Würzburg, Germany
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Oleg Moskvin
- Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
- Singapore Medical School, BluMaiden Biosciences, Singapore, Singapore
| | - Aayushi Y Jain
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Nikita Gorbunov
- Division of Molecular Psychiatry, Center of Mental Health, University Hospital of Würzburg, Würzburg, Germany
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Anna Gorlova
- Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine and Department of Normal Physiology, Sechenov Moscow State Medical University, Moscow, Russia
| | - Daria Sadovnik
- Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine and Department of Normal Physiology, Sechenov Moscow State Medical University, Moscow, Russia
| | - Aleksei Umriukhin
- Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine and Department of Normal Physiology, Sechenov Moscow State Medical University, Moscow, Russia
| | - Raymond Cespuglio
- Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine and Department of Normal Physiology, Sechenov Moscow State Medical University, Moscow, Russia
- Neuroscience Research Center of Lyon, Beliv Plateau, Claude-Bernard Lyon-1 University, Bron, France
| | - Wing Shan Yu
- Neuromodulation Laboratory, School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR, China
| | - Anna Chung Kwan Tse
- Neuromodulation Laboratory, School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR, China
| | - Allan V Kalueff
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Center of Mental Health, University Hospital of Würzburg, Würzburg, Germany.
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
| | - Lee Wei Lim
- Neuromodulation Laboratory, School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR, China.
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Zhang Y, Wang Y, Zhang K, Liang X, Guan J, Jin J, Zhang Y, Xu F, Yang L, Fu J. Profile of 5-HT 2A receptor involved in signaling cascades associated to intracellular inflammation and apoptosis in hepatocytes and its role in carbon tetrachloride-induced hepatotoxicity. Cell Signal 2023; 105:110612. [PMID: 36709823 DOI: 10.1016/j.cellsig.2023.110612] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 01/14/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023]
Abstract
Previously, we found that the 5-HT2A receptor plays a key role in cell injury. However, the mechanism by which the 5-HT2A receptor mediates intracellular processes remains unclear. In this study, we aimed to clarify this intracellular process in hepatocyte LO2 cells and evaluate its role in CCl4-induced hepatotoxicity in mice. In vitro, both the agonist and overexpression of 5-HT2A receptor could promote 5-HT degradation by upregulating the expression of 5-HT synthases and monoamine oxidase-A (MAO-A) to cause overproduction of ROS in mitochondria. We refer to this as the activation of the 5-HT degradation system (5DS) axis, which leads to the phosphorylation of JNK, p38 MAPK, STAT3, and NF-κB; upregulation of Bax, cleaved-caspase3, and cleaved-caspase9; and downregulation of Bcl-2, followed by apoptosis and oversecretion of TNF-α and IL-1β in cells. This phenomenon could be markedly blocked by the 5-HT2A receptor antagonist, MAO-A inhibitor, or gene-silencing MAO-A. Through protein kinases C epsilon (PKCε) agonist treatment and gene silencing of the PKCε and 5-HT2A receptor, we demonstrated that the 5-HT2A receptor controls 5-HT synthases and MAO-A expression via the PKCε pathway in cells. Unexpectedly, we discovered that PKCε-mediated phosphorylation of the AKT/mTOR pathway is also a consequence of the activation of the 5DS axis. Furthermore, we confirmed that the inhibition of the 5DS axis using the 5-HT2A receptor antagonist could prevent hepatotoxicity induced by CCl4 both in vitro and in vivo, inhibiting the aforementioned signaling cascades, inflammation, and apoptosis, and that the 5DS activation area overlapped the necrotic area of mouse liver. Taken together, we revealed a 5DS axis in hepatocytes that controls the signaling cascades associated with inflammation and apoptosis and confirmed its role in CCl4-induced hepatotoxicity.
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Affiliation(s)
- Yuxin Zhang
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Yizhou Wang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, Nanjing 210009, China
| | - Kun Zhang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, Nanjing 210009, China
| | - Xiurui Liang
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Jing Guan
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Jiaqi Jin
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Yi Zhang
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Fan Xu
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Lin Yang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, Nanjing 210009, China.
| | - Jihua Fu
- Department of Physiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China.
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Shin EJ, Jeong JH, Nguyen BT, Sharma N, Nah SY, Chung YH, Lee Y, Byun JK, Nabeshima T, Ko SK, Kim HC. Ginsenoside Re Protects against Serotonergic Behaviors Evoked by 2,5-Dimethoxy-4-iodo-amphetamine in Mice via Inhibition of PKCδ-Mediated Mitochondrial Dysfunction. Int J Mol Sci 2021; 22:ijms22137219. [PMID: 34281274 PMCID: PMC8268959 DOI: 10.3390/ijms22137219] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/26/2021] [Accepted: 06/29/2021] [Indexed: 02/07/2023] Open
Abstract
It has been recognized that serotonin 2A receptor (5-HT2A) agonist 2,5-dimethoxy-4-iodo-amphetamine (DOI) impairs serotonergic homeostasis. However, the mechanism of DOI-induced serotonergic behaviors remains to be explored. Moreover, little is known about therapeutic interventions against serotonin syndrome, although evidence suggests that ginseng might possess modulating effects on the serotonin system. As ginsenoside Re (GRe) is well-known as a novel antioxidant in the nervous system, we investigated whether GRe modulates 5-HT2A receptor agonist DOI-induced serotonin impairments. We proposed that protein kinase Cδ (PKCδ) mediates serotonergic impairments. Treatment with GRe or 5-HT2A receptor antagonist MDL11939 significantly attenuated DOI-induced serotonergic behaviors (i.e., overall serotonergic syndrome behaviors, head twitch response, hyperthermia) by inhibiting mitochondrial translocation of PKCδ, reducing mitochondrial glutathione peroxidase activity, mitochondrial dysfunction, and mitochondrial oxidative stress in wild-type mice. These attenuations were in line with those observed upon PKCδ inhibition (i.e., pharmacologic inhibitor rottlerin or PKCδ knockout mice). Furthermore, GRe was not further implicated in attenuation mediated by PKCδ knockout in mice. Our results suggest that PKCδ is a therapeutic target for GRe against serotonergic behaviors induced by DOI.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Korea; (E.-J.S.); (B.-T.N.); (N.S.)
| | - Ji Hoon Jeong
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, College of Medicine, Chung-Ang University, Seoul 06974, Korea;
| | - Bao-Trong Nguyen
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Korea; (E.-J.S.); (B.-T.N.); (N.S.)
| | - Naveen Sharma
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Korea; (E.-J.S.); (B.-T.N.); (N.S.)
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, College of Medicine, Chung-Ang University, Seoul 06974, Korea;
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory, Department of Physiology, College of Veterinary Medicine and Bio/Molecular Informatics Center, Konkuk University, Seoul 05029, Korea;
| | - Yoon Hee Chung
- Department of Anatomy, College of Medicine, Chung-Ang University, Seoul 06974, Korea;
| | - Yi Lee
- Department of Industrial Plant Science & Technology, Chungbuk National University, Chungju 28644, Korea;
| | - Jae Kyung Byun
- Korea Society of Forest Environmental Research, Namyanju 12106, Korea;
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake 470-1192, Japan;
| | - Sung Kwon Ko
- Department of Oriental Medical Food and Nutrition, Semyung University, Jecheon 27136, Korea
- Correspondence: (S.K.K.); (H.-C.K.); Tel.: +82-33-250-6917 (H.-C.K.); Fax: +82-33-259-5631 (H.-C.K.)
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Korea; (E.-J.S.); (B.-T.N.); (N.S.)
- Correspondence: (S.K.K.); (H.-C.K.); Tel.: +82-33-250-6917 (H.-C.K.); Fax: +82-33-259-5631 (H.-C.K.)
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Stachowicz K. Indomethacin, a nonselective cyclooxygenase inhibitor, does not interact with MTEP in antidepressant-like activity, as opposed to imipramine in CD-1 mice. Eur J Pharmacol 2020; 888:173585. [PMID: 32971092 DOI: 10.1016/j.ejphar.2020.173585] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/16/2020] [Accepted: 09/17/2020] [Indexed: 02/03/2023]
Abstract
The contribution of metabotropic glutamate receptors (mGlu receptors) in depression is well known and tested worldwide. Our previous study showed the involvement of the cyclooxygenase-2 (COX-2) pathway in behavioral changes mediated by an antagonist of metabotropic glutamate receptor subtype 5 (mGlu5 receptor) 3-[(2-methyl-1,3-tiazol-4-yl)ethynyl]-pyridine (MTEP). Among others, we have found that chronic concomitant administration of a COX-2 inhibitor and sub-effective dose of MTEP accelerates antidepressant-like activity of MTEP. This paper seeks to explore whether the same effect would be observed with the use of a non-selective COX inhibitor 2-[1-(4-chlorobenzoyl)-5-methoxy-2-methylindol-3-yl]acetic acid (indomethacin). To that end, we have employed experimental procedure implemented in the earlier research. MTEP and indomethacin or MTEP + indomethacin were used chronically for 7 or 14 days. Then, the Porsolt test, tail suspension test and locomotor activity test were performed. Imipramine was used as a reference compound, as its action is connected with mGlu5 receptor. We found that, in contrast to COX-2 inhibition, indomethacin - acting both through COX-1 and COX-2 - did not release antidepressant-like potential of MTEP. The opposite effect was shown when imipramine was used.
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Affiliation(s)
- Katarzyna Stachowicz
- Department of Neurobiology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland.
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Phan DH, Shin EJ, Sharma N, Hoang Yen TP, Dang DK, Lee YS, Lee YJ, Nah SY, Cheong JH, Jeong JH, Kim HC. 5-HT 2A receptor-mediated PKCδ phosphorylation is critical for serotonergic impairments induced by p-chloroamphetamine in mice. Food Chem Toxicol 2020; 141:111395. [PMID: 32437895 DOI: 10.1016/j.fct.2020.111395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/18/2020] [Accepted: 04/29/2020] [Indexed: 02/06/2023]
Abstract
p-Chloroamphetamine (PCA), an amphetamine derivative, has been shown to induce serotonergic toxicity. However, the precise mechanism of serotonergic toxicity induced by PCA remains unclear. In this study, PCA treatment (20 mg/kg, i.p.) did not significantly change 5-HT1A receptor gene expression, but significantly increased 5-HT2A receptor gene expression. Furthermore, 5-HT2A receptor antagonist MDL11939, but not 5-HT1A receptor antagonist WAY100635, significantly attenuated PCA-induced serotonergic impairments. We investigated whether PCA activated a specific isoform of protein kinase C (PKC), since previous evidence indicated the involvement of PKC in neurotoxicity induced by amphetamines. We observed that PCA treatment significantly increased the expression levels of PKCδ among all PKC isoforms. MDL11939 treatment significantly attenuated PCA-induced phosphorylation of PKCδ. However, PCA-induced increase in 5-HT2A receptor gene expression was not altered by rottlerin (a pharmacological inhibitor of PKCδ) in mice, suggesting that 5-HT2A receptor is an upstream molecule for the activation of PKCδ. Rottlerin or PKCδ knockout significantly attenuated serotonergic behaviors. However, MDL11939 did not show any additional effects against the attenuation caused by PKCδ knockout in mice, suggesting that PKCδ gene is a molecular target for 5-HT2A receptor-mediated serotonergic effects. Our results suggest that 5-HT2A receptor mediates PCA-induced serotonergic impairments via activation of PKC.δ.
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Affiliation(s)
- Dieu Hien Phan
- Neuropsychopharmacology and Toxicology Program, BK21 PLUS Project, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea; School of Medicine and Pharmacy - Hoa Quy Ward, The University of Da Nang, Da Nang 550000, Viet Nam
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, BK21 PLUS Project, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Naveen Sharma
- Neuropsychopharmacology and Toxicology Program, BK21 PLUS Project, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Tran Phi Hoang Yen
- Faculty of Pharmacy, University of Medicine and Pharmacy of Ho Chi Minh City, 710000, Viet Nam
| | - Duy-Khanh Dang
- Pharmacy Faculty, Can Tho University of Medicine and Pharmacy, Can Tho City, 900000, Viet Nam
| | - Yong Sup Lee
- Department of Life and Nanopharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Yu Jeung Lee
- Clinical Pharmacy, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine and Bio/Molecular Informatics Center, Konkuk University, Seoul, 05029, Republic of Korea
| | - Jae Hoon Cheong
- Department of Pharmacy, Sahmyook University, Seoul, 01795, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, BK21 PLUS Project, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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NS398, a cyclooxygenase-2 inhibitor, reverses memory performance disrupted by imipramine in C57Bl/6J mice. Brain Res 2020; 1734:146741. [PMID: 32088181 DOI: 10.1016/j.brainres.2020.146741] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 11/21/2022]
Abstract
Imipramine has been widely used as an antidepressant in the clinic over the years. Unfortunately, it produces a detrimental effect on memory. At the same time, COX-2 inhibitors engagement in the mechanisms of memory formation, and synapse plastic changes has been well documented. Our previous studies have demonstrated the contribution of cyclooxygenase-2 (COX-2) inhibition to the parameters of the mGluR5 pathway in memory formation. Because chronic administration of imipramine has been shown to affect mGluR5, the purpose of this study was to verify the hypothesis of COX-2 pathway engagement in disrupting effects of imipramine. Imipramine is currently used as a reference compound, and therefore it seems important to decipher and understand mood-related pathways, as well as cognitive changes activated during its use. This study covers the examination of spatial, and motor parameters. To this end, C57Bl/6J mice received imipramine, and NS398 (a COX-2 inhibitor) alone, or in combination for 7 or 14 days. We performed the modified Barnes maze (MBM), modified rotarod (MR) tests, and electrophysiological studies. The harmful effect of imipramine on MBM learning was improved by NS398 use. The same modulatory role of the COX-2 inhibitor in procedural learning in the MR test was found. In conclusion, our data show the involvement of the COX-2 pathway in changes in the long-term memory, and procedural memory of C57Bl/6J mice after chronic imipramine treatment.
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Abiero A, Botanas CJ, Sayson LV, Custodio RJ, de la Peña JB, Kim M, Lee HJ, Seo JW, Ryu IS, Chang CM, Yang JS, Lee YS, Jang CG, Kim HJ, Cheong JH. 5-Methoxy-α-methyltryptamine (5-MeO-AMT), a tryptamine derivative, induces head-twitch responses in mice through the activation of serotonin receptor 2a in the prefrontal cortex. Behav Brain Res 2019; 359:828-835. [DOI: 10.1016/j.bbr.2018.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/10/2018] [Accepted: 07/24/2018] [Indexed: 12/20/2022]
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Felsing DE, Canal CE, Booth RG. Ligand-directed serotonin 5-HT 2C receptor desensitization and sensitization. Eur J Pharmacol 2019; 848:131-139. [PMID: 30689993 DOI: 10.1016/j.ejphar.2019.01.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/31/2022]
Abstract
Exposure of G protein-coupled receptors (GPCRs) to agonists can desensitize receptor signaling and lead to drug tolerance, whereas inverse agonists can sensitize signaling. For example, activation of serotonin 5-HT2C GPCRs is pharmacotherapeutic for obesity, but there is tolerance to the anorectic effect of the only approved 5-HT2C agonist, lorcaserin. We tested the hypothesis that different agonists or inverse agonists differentially desensitize or sensitize, respectively, canonical 5-HT2C-mediated activation of phospholipase C (PLC) signaling in vitro. Lorcaserin, which displays potency and efficacy equal to 5-HT, desensitized the 5-HT2C receptor significantly more than 5-HT (p<0.05). Agonist chemotypes such as 2-aminotetralins, with similar potency but lower efficacy than 5-HT, produced little 5-HT2C desensitization. The piperazine agonist 1-(3-chlorophenyl)piperazine (mCPP), with lower potency but similar efficacy as 5-HT, elicited desensitization indistinguishable from 5-HT, while the piperazine agonist aripiprazole, with lower potency and efficacy, did not desensitize 5-HT2C-PLC signaling. Several 5-HT2C agonists also were assessed for β-arrestin recruitment-lorcaserin was a 'super-agonist', but a 2-aminotetralin and aripiprazole had nil activity, suggesting they are biased towards 5-HT2C-PLC signaling. We observed robust positive correlations between the magnitude of 5-HT2C desensitization and agonist efficacy to stimulate PLC or to recruit β-arrestin. In contrast, different inverse agonists caused different magnitudes of 5-HT2C sensitization that did not correlate with efficacy (or potency) to inhibit constitutive 5-HT2C-PLC signaling. Assessment of the 5-HT2C-S407A point-mutated receptor indicated this residue's involvement in ligand-dependent desensitization, but we did not observe a role for protein kinase C.These data show that ligand structure uniquely impacts 5-HT2C desensitization and sensitization processes..
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Affiliation(s)
- Daniel E Felsing
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, United States.
| | - Clinton E Canal
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States.
| | - Raymond G Booth
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, United States; Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, United States.
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9
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Tran HQ, Shin EJ, Hoai Nguyen BC, Phan DH, Kang MJ, Jang CG, Jeong JH, Nah SY, Mouri A, Saito K, Nabeshima T, Kim HC. 5-HT 1A receptor agonist 8-OH-DPAT induces serotonergic behaviors in mice via interaction between PKCδ and p47phox. Food Chem Toxicol 2018; 123:125-141. [PMID: 30366073 DOI: 10.1016/j.fct.2018.10.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/18/2018] [Accepted: 10/22/2018] [Indexed: 12/22/2022]
Abstract
Serotonin syndrome is an adverse reaction due to increased serotonin (5-hydroxytryptophan: 5-HT) concentrations in the central nervous system (CNS). The full 5-HT1A receptor (5-HT1AR) agonist (±)-8-hydroxy-dipropylaminotetralin (8-OH-DPAT) has been recognized to elicit traditional serotonergic behaviors. Treatment with 8-OH-DPAT selectively increased PKCδ expression out of PKC isoforms and 5-HT turnover rate in the hypothalamus of wild-type mice. Treatment with 8-OH-DPAT resulted in oxidative burdens, co-immunoprecipitation of 5-HT1AR and PKCδ, and phosphorylation and membrane translocation of p47phox. Importantly, p47phox also interacted with 5-HT1AR or PKCδ in the presence of 8-OH-DPAT. Consistently, the interaction and oxidative burdens were attenuated by 5-HT1AR antagonism (i.e., WAY100635), PKCδ inhibition (i.e., rottlerin and genetic depletion of PKCδ), or NADPH oxidase/p47phox inhibition (i.e., apocynin and genetic depletion of p47phox). However, WAY100635, apocynin, or rottlerin did not exhibit any additive effects against the protective effect by inhibition of PKCδ or p47phox. Furthermore, apocynin, rottlerin, or WAY100635 also significantly protected from pro-inflammatory/pro-apoptotic changes induced by 8-OH-DPAT. Therefore, we suggest that 8-OH-DPAT-induced serotonergic behaviors requires oxidative stress, pro-inflammatory, and pro-apoptotic changes, that PKCδ or p47phox mediates the serotonergic behaviors induced by 8-OH-DPAT, and that the inhibition of PKCδ-dependent p47phox activation is critical for protecting against serotonergic behaviors.
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Affiliation(s)
- Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Bao-Chau Hoai Nguyen
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Dieu-Hien Phan
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Min-Ji Kang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul, 05029, Republic of Korea
| | - Akihiro Mouri
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi, 470-1192, Japan
| | - Kuniaki Saito
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi, 470-1192, Japan
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi, 470-1192, Japan; Aino University, Ibaraki, 576-0012, Japan; Japanese Drug Organization of Appropriate and Research, Nagoya, 468-0069, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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Acton D, Miles GB. Differential regulation of NMDA receptors by d-serine and glycine in mammalian spinal locomotor networks. J Neurophysiol 2017; 117:1877-1893. [PMID: 28202572 PMCID: PMC5411468 DOI: 10.1152/jn.00810.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/11/2017] [Accepted: 02/11/2017] [Indexed: 12/11/2022] Open
Abstract
We provide evidence that NMDARs within murine spinal locomotor networks determine the frequency and amplitude of ongoing locomotor-related activity in vitro and that NMDARs are regulated by d-serine and glycine in a synapse-specific and activity-dependent manner. In addition, glycine transporter-1 is shown to be an important regulator of NMDARs during locomotor-related activity. These results show how excitatory transmission can be tuned to diversify the output repertoire of spinal locomotor networks in mammals. Activation of N-methyl-d-aspartate receptors (NMDARs) requires the binding of a coagonist, either d-serine or glycine, in addition to glutamate. Changes in occupancy of the coagonist binding site are proposed to modulate neural networks including those controlling swimming in frog tadpoles. Here, we characterize regulation of the NMDAR coagonist binding site in mammalian spinal locomotor networks. Blockade of NMDARs by d(−)-2-amino-5-phosphonopentanoic acid (d-APV) or 5,7-dichlorokynurenic acid reduced the frequency and amplitude of pharmacologically induced locomotor-related activity recorded from the ventral roots of spinal-cord preparations from neonatal mice. Furthermore, d-APV abolished synchronous activity induced by blockade of inhibitory transmission. These results demonstrate an important role for NMDARs in murine locomotor networks. Bath-applied d-serine enhanced the frequency of locomotor-related but not disinhibited bursting, indicating that coagonist binding sites are saturated during the latter but not the former mode of activity. Depletion of endogenous d-serine by d-amino acid oxidase or the serine-racemase inhibitor erythro-β-hydroxy-l-aspartic acid (HOAsp) increased the frequency of locomotor-related activity, whereas application of l-serine to enhance endogenous d-serine synthesis reduced burst frequency, suggesting a requirement for d-serine at a subset of synapses onto inhibitory interneurons. Consistent with this, HOAsp was ineffective during disinhibited activity. Bath-applied glycine (1–100 µM) failed to alter locomotor-related activity, whereas ALX 5407, a selective inhibitor of glycine transporter-1 (GlyT1), enhanced burst frequency, supporting a role for GlyT1 in NMDAR regulation. Together these findings indicate activity-dependent and synapse-specific regulation of the coagonist binding site within spinal locomotor networks, illustrating the importance of NMDAR regulation in shaping motor output. NEW & NOTEWORTHY We provide evidence that NMDARs within murine spinal locomotor networks determine the frequency and amplitude of ongoing locomotor-related activity in vitro and that NMDARs are regulated by d-serine and glycine in a synapse-specific and activity-dependent manner. In addition, glycine transporter-1 is shown to be an important regulator of NMDARs during locomotor-related activity. These results show how excitatory transmission can be tuned to diversify the output repertoire of spinal locomotor networks in mammals.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
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Idkowiak-Baldys J, Baldys A, Raymond JR, Hannun YA. Sustained receptor stimulation leads to sequestration of recycling endosomes in a classical protein kinase C- and phospholipase D-dependent manner. J Biol Chem 2009; 284:22322-22331. [PMID: 19525236 PMCID: PMC2755955 DOI: 10.1074/jbc.m109.026765] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Indexed: 11/06/2022] Open
Abstract
Considerable insight has been garnered on initial mechanisms of endocytosis of plasma membrane proteins and their subsequent trafficking through the endosomal compartment. It is also well established that ligand stimulation of many plasma membrane receptors leads to their internalization. However, stimulus-induced regulation of endosomal trafficking has not received much attention. In previous studies, we showed that sustained stimulation of protein kinase C (PKC) with phorbol esters led to sequestration of recycling endosomes in a juxtanuclear region. In this study, we investigated whether G-protein-coupled receptors that activate PKC exerted effects on endosomal trafficking. Stimulation of cells with serotonin (5-hydroxytryptamine (5-HT)) led to sequestration of the 5-HT receptor (5-HT2AR) into a Rab11-positive juxtanuclear compartment. This sequestration coincided with translocation of PKC as shown by confocal microscopy. Mechanistically the observed sequestration of 5-HT2AR was shown to require continuous PKC activity because it was inhibited by pretreatment with classical PKC inhibitor Gö6976 and could be reversed by posttreatment with this inhibitor. In addition, classical PKC autophosphorylation was necessary for receptor sequestration. Moreover inhibition of phospholipase D (PLD) activity and inhibition of PLD1 and PLD2 using dominant negative constructs also prevented this process. Functionally this sequestration did not affect receptor desensitization or resensitization as measured by intracellular calcium increase. However, the PKC- and PLD-dependent sequestration of receptors resulted in co-sequestration of other plasma membrane proteins and receptors as shown for epidermal growth factor receptor and protease activated receptor-1. This led to heterologous desensitization of those receptors and diverted their cellular fate by protecting them from agonist-induced degradation. Taken together, these results demonstrate a novel role for sustained receptor stimulation in regulation of intracellular trafficking, and this process requires sustained stimulation of PKC and PLD.
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Affiliation(s)
| | - Aleksander Baldys
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and
- Medical and Research Services, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
| | - John R. Raymond
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and
- Medical and Research Services, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
| | - Yusuf A. Hannun
- From the Department of Biochemistry and Molecular Biology and
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Morioka N, Abdin JM, Morita K, Kitayama T, Nakata Y, Dohi T. The regulation of glycine transporter GLYT1 is mainly mediated by protein kinase Cα in C6 glioma cells. Neurochem Int 2008; 53:248-54. [DOI: 10.1016/j.neuint.2008.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 08/08/2008] [Accepted: 08/08/2008] [Indexed: 11/29/2022]
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Spitzer N, Cymbalyuk G, Zhang H, Edwards DH, Baro DJ. Serotonin transduction cascades mediate variable changes in pyloric network cycle frequency in response to the same modulatory challenge. J Neurophysiol 2008; 99:2844-63. [PMID: 18400960 DOI: 10.1152/jn.00986.2007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A fundamental question in systems biology addresses the issue of how flexibility is built into modulatory networks such that they can produce context-dependent responses. Here we examine flexibility in the serotonin (5-HT) response system that modulates the cycle frequency (cf) of a rhythmic motor output. We found that depending on the preparation, the same 5-min bath application of 5-HT to the pyloric network of the California spiny lobster, Panulirus interruptus, could produce a significant increase, decrease, or no change in steady-state cf relative to baseline. Interestingly, the mean circuit output was not significantly different among preparations prior to 5-HT application. We developed pharmacological tools to examine the preparation-to-preparation variability in the components of the 5-HT response system. We found that the 5-HT response system consisted of at least three separable components: a 5-HT(2betaPan)-like component mediated a rapid decrease followed by a sustained increase in cf; a 5-HT(1alphaPan)-like component produced a small and usually gradual increase in cf; at least one other component associated with an unknown receptor mediated a sustained decrease in cf. The magnitude of the change in cf produced by each component was highly variable, so that when summed they could produce either a net increase, decrease, or no change in cf depending on the preparation. Overall, our research demonstrates that the balance of opposing components of the 5-HT response system determines the direction and magnitude of 5-HT-induced change in steady-state cf relative to baseline.
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Affiliation(s)
- Nadja Spitzer
- Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, GA 30302-4010, USA
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Shi J, Zemaitaitis B, Muma NA. Phosphorylation of Galpha11 protein contributes to agonist-induced desensitization of 5-HT2A receptor signaling. Mol Pharmacol 2006; 71:303-13. [PMID: 17056873 DOI: 10.1124/mol.106.028241] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Agonist treatment causes desensitization of many G protein-coupled receptor systems. Recent advances have delineated changes in receptors in the desensitization response; however, the role of G proteins remains unclear. We investigated the role of phosphorylation of Galpha q/11 proteins in agonist-induced desensitization of serotonin 2A (5-HT2A) receptors. In an embryonic rat cortical cell line (A1A1v), 24-h treatment with 100 nM (-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI), a 5-HT(2A/2C) receptor agonist, decreased DOI-stimulated inositol phosphate accumulation and increased the phosphorylation of Galpha q/11 proteins, as demonstrated by immunoprecipitation of Galpha q/11 and both incorporation of 32P phosphate and labeling with a S/T/Y phosphorylation-dependent antibody. Treatment with DOI for 30 min induced desensitization but did not increase phosphorylation of Galpha q/11 proteins, suggesting that different mechanisms are involved in desensitization after short- and long-term treatments. Mutation of S154A in a protein kinase C (PKC) and calcium/calmodulin dependent kinase (CaMK) consensus site in Galpha11 significantly reduced DOI-stimulated phosphorylation of Galpha11 and DOI-induced desensitization of 5-HT2A receptor signaling. Inhibition of PKC and CaMK attenuated phosphorylation of Galpha q/11 proteins and DOI-induced desensitization of 5-HT2A receptors. Expression of Galpha11 S154D, a phosphorylation mimic, reduced DOI-stimulated inositol phosphate accumulation. DOI treatment for 24 h also produced heterologous desensitization, as indicated by decreased bradykinin-stimulated inositol phosphate accumulation. These data suggest that phosphorylation of Galpha11 protein by PKC and CaMK contributes to agonist-induced homologous desensitization of 5-HT2A receptor signaling as well as heterologous desensitization. The phosphorylation of Galpha protein represents a novel mechanism involved in regulation of receptor signaling and agonist-induced desensitization of G protein-coupled receptors.
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Affiliation(s)
- Ju Shi
- Department of Pharmacology Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
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Bowers BJ, Miyamoto-Ditmon J, Wehner JM. Regulation of 5-HT2A/C receptors and DOI-induced behaviors by protein kinase Cgamma. Pharmacol Biochem Behav 2006; 85:441-7. [PMID: 17109939 PMCID: PMC1868423 DOI: 10.1016/j.pbb.2006.09.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 09/13/2006] [Accepted: 09/26/2006] [Indexed: 11/15/2022]
Abstract
Protein kinase Cgamma (PKCgamma) null mutant mice demonstrate increased behavioral impulsivity and ethanol consumption. Pharmacological studies have shown that 5-HT(2A/C) receptors modulate impulsivity and ethanol consumption in rodents and that PKC can regulate 5-HT(2A/C) receptors. To determine whether PKCgamma plays a selective role in 5-HT(2A/C) receptor regulation, biochemical and behavioral experiments were performed in PKCgamma mutant and wild-type mice. DOI-stimulated phosphoinositol hydrolysis and [(125)I]-DOI saturation binding in the PFC, and quantitative autoradiography of [(125)I]-DOI binding sites in 15 brain regions were analyzed. DOI-induced head twitch responses (HTR) were measured in naive mice after an acute 2.5 mg/kg injection of DOI. Results indicated that DOI-induced HTR was significantly greater in mutant mice compared to wild-type mice. Results of the phosphoinositol hydrolysis, membrane binding, and autoradiography experiments indicated that in mutant mice, increased HTR was associated with increased 5-HT(2A/C) receptor function in the PFC, but not increased receptor number or affinity suggesting that PKCgamma regulates receptor function but not receptor number. These data support a role for 5-HT(2A/C) receptors in the PFC in mediating some of the behavioral differences observed between PKCgamma mutant and wild-type mice.
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Affiliation(s)
- Barbara J Bowers
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA.
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Saini HK, Takeda N, Goyal RK, Kumamoto H, Arneja AS, Dhalla NS. Therapeutic Potentials of Sarpogrelate in Cardiovascular Disease*. ACTA ACUST UNITED AC 2006; 22:27-54. [PMID: 14978517 DOI: 10.1111/j.1527-3466.2004.tb00130.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In view of the pivotal role of serotonin (5-HT) in a wide variety of cardiovascular disorders, extensive effort has been made to develop different types of 5-HT receptor antagonists for therapeutic use. On the basis of experimental studies, this article is focused on the potentials of sarpogrelate, a specific 5-HT2A receptor antagonist as an antiplatelet, antithrombotic, antiatherosclerotic and antianginal agent. The major effects of sarpogrelate are due to the inhibition of 5-HT-induced platelet aggregation and smooth muscle cell proliferation. This agent was found to attenuate the 5-HT-mediated increase in intracellular Ca2+ and ischemia-reperfusion injury in the heart. Sarpogrelate has been found to have beneficial effects in peripheral vascular disease, restenosis after coronary stenting, pulmonary hypertension, acute and chronic myocardial infarction.
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Affiliation(s)
- Harjot K Saini
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Department of Physiology, University of Manitoba, 351 Tache Avenue, Winnipeg, Manitoba R2H 2A6, Canada
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Van Oekelen D, Luyten WHML, Leysen JE. 5-HT2A and 5-HT2C receptors and their atypical regulation properties. Life Sci 2003; 72:2429-49. [PMID: 12650852 DOI: 10.1016/s0024-3205(03)00141-3] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The 5-HT(2A) and 5-HT(2C) receptors belong to the G-protein-coupled receptor (GPCR) superfamily. GPCRs transduce extracellular signals to the interior of cells through their interaction with G-proteins. The 5-HT(2A) and 5-HT(2C) receptors mediate effects of a large variety of compounds affecting depression, schizophrenia, anxiety, hallucinations, dysthymia, sleep patterns, feeding behaviour and neuro-endocrine functions. Binding of such compounds to either 5-HT(2) receptor subtype induces processes that regulate receptor sensitivity. In contrast to most other receptors, chronic blockade of 5-HT(2A) and 5-HT(2C) receptors leads not to an up- but to a (paradoxical) down-regulation. This review deals with published data involving such non-classical regulation of 5-HT(2A) and 5-HT(2C) receptors obtained from in vivo and in vitro studies. The underlying regulatory processes of the agonist-induced regulation of 5-HT(2A) and 5-HT(2C) receptors, commonly thought to be desensitisation and resensitisation, are discussed. The atypical down-regulation of both 5-HT(2) receptor subtypes by antidepressants, antipsychotics and 5-HT(2) antagonists is reviewed. The possible mechanisms of this paradoxical down-regulation are discussed, and a new hypothesis on possible heterologous regulation of 5-HT(2A) receptors is proposed.
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Affiliation(s)
- Dirk Van Oekelen
- Johnson and Johnson Pharmaceutical, p/a Janssen Pharmaceutica, Turnhoutseweg 30, B-2340 Beerse, Belgium
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Hanley NRS, Hensler JG. Mechanisms of ligand-induced desensitization of the 5-hydroxytryptamine(2A) receptor. J Pharmacol Exp Ther 2002; 300:468-77. [PMID: 11805206 DOI: 10.1124/jpet.300.2.468] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We have examined the cellular processes underlying the desensitization of the 5-hydroxytryptamine (5-HT)(2A) receptor induced by agonist or antagonist exposure. Treatment of C6 glioma cells with either 5-HT or the 5-HT(2A) receptor antagonist ketanserin resulted in an attenuation in 5-HT(2A) receptor function, specifically the accumulation of inositol phosphates stimulated by the partial agonist quipazine. 5-HT-induced desensitization of the 5-HT(2A) receptor involved receptor internalization through a clathrin- and dynamin-dependent process because it was prevented by concanavalin A, monodansylcadaverine, and by expression of the dominant negative mutants beta-arrestin (319-418) and dynamin K44A. Although short-term (i.e., 10 min) 5-HT and ketanserin exposure resulted in the same degree of desensitization, ketanserin-induced desensitization was not prevented by these agents and did not involve receptor internalization. In contrast, prolonged ketanserin exposure (i.e., 2 h) resulted in 5-HT(2A) receptor internalization through a clathrin- and dynamin-dependent process, as was observed after agonist treatment. Inhibitors of protein kinase C or calcium-calmodulin kinase II did not attenuate or prevent 5-HT-induced desensitization of the receptor. 5-HT(2A) receptor desensitization induced by 5-HT and prolonged ketanserin treatment, but not by short-term ketanserin treatment, was prevented by the expression of the dominant negative mutant of G protein-coupled receptor kinase (GRK)2, GRK2-K220R, and by an anti-GRK2/3 antibody. Our data indicate a dual mechanism of early and late desensitization by the antagonist ketanserin. Short-term ketanserin treatment reduced the specific binding of the agonist radioligand [(125)I](+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ([(125)I]DOI) and the ability of 5'-guanylylimidodiphosphate to attenuate this binding, suggesting that at the early stage of antagonist-induced desensitization the capacity of the 5-HT(2A) receptor to couple to G protein is impaired.
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Affiliation(s)
- Nicole R Sullivan Hanley
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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