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Effect of the dietary intake of fish oil on psycho-social behavioral disorder caused by social-defeat stress. Physiol Behav 2022; 254:113913. [PMID: 35835180 DOI: 10.1016/j.physbeh.2022.113913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/27/2022] [Accepted: 07/10/2022] [Indexed: 11/22/2022]
Abstract
Exposure to psychosocial stress is a risk factor for human diseases such as depression. Social defeat stress (SDS) is a well-known rodent model of human psychosocial stress, and animals exposed to SDS show social avoidance behavior. Fish oil, which is rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), is expected to decrease the risk of depressive disorders. In this study, we determined whether fish oil affects the social behavior of SDS-exposed mice and measured serotonin levels and expression of genes related to tryptophan (TRP) metabolism in the hippocampus. The experimental animals were fed a diet containing fish oil during SDS exposure. For the fish oil treatment, experimental mice were fed a diet containing fish oil at low (L-FO), middle (M-FO), and high (H-FO) concentrations. The control group was supplemented with an equivalent amount of canola oil (no fish oil: N-FO). After the SDS protocol, we performed a social interaction test and assessed the sociality of experimental mice. In the N-FO group, SDS-exposed mice showed negative social interactions compared with non-stressed mice. The L-FO and H-FO groups showed negative social interactions after SDS exposure; however, the M-FO group did not exhibit negative social behavior. The serotonin levels of SDS-exposed mice were lower than those of non-stressed mice in the N-FO group. In contrast with these results in the N-FO group, there was no difference in serotonin levels between SDS-exposed and non-stressed mice in the FO groups. In addition, the expression of genes related to TRP metabolism in SDS-exposed mice increased in the N-FO group, but not in the FO group. These results suggest that fish oil improves the psychosocial behavioral disorders caused by SDS. This improvement could be explained by the increase in serotonin synthesis in the hippocampus.
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Vizcarra VS, Barber KR, Franca-Solomon G, Majuta L, Smith A, Langlais PR, Largent-Milnes TM, Vanderah TW, Riegel AC. Targeting 5-HT 2A receptors and Kv7 channels in PFC to attenuate chronic neuropathic pain in rats using a spared nerve injury model. Neurosci Lett 2022; 789:136864. [PMID: 36063980 PMCID: PMC10088904 DOI: 10.1016/j.neulet.2022.136864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 10/14/2022]
Abstract
Chronic pain remains a disabling disease with limited therapeutic options. Pyramidal neurons in the prefrontal cortex (PFC) express excitatory Gq-coupled 5-HT2A receptors (5-HT2AR) and their effector system, the inhibitory Kv7 ion channel. While recent publications show these cells innervate brainstem regions important for regulating pain, the cellular mechanisms underlying the transition to chronic pain are not well understood. The present study examined whether local blockade of 5-HT2AR or enhanced Kv7 ion channel activity in the PFC would attenuate mechanical allodynia associated with spared nerve injury (SNI) in rats. Following SNI, we show that inhibition of PFC 5-HT2ARs with M100907 or opening of PFC Kv7 channels with retigabine reduced mechanical allodynia. Parallel proteomic and RNAScope experiments evaluated 5-HT2AR/Kv7 channel protein and mRNA. Our results support the role of 5-HT2ARs and Kv7 channels in the PFC in the maintenance of chronic pain.
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Affiliation(s)
- Velia S Vizcarra
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA; Translational Biomedical Sciences Graduate Program, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box URNI, Rochester, NY, 14642, USA
| | - Kara R Barber
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA
| | - Gabriela Franca-Solomon
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA
| | - Lisa Majuta
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA
| | - Angela Smith
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA; Interdisciplinary Graduate Program in Neuroscience, University of Iowa, 52242, USA
| | - Paul R Langlais
- Department of Medicine, Division of Endocrinology, University of Arizona College of Medicine, Tucson, Arizona, 85721, USA
| | - Tally M Largent-Milnes
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA; Neuroscience Graduate Interdisciplinary Program, University of Arizona, Tucson, Arizona, 85721, USA; Comprehensive Pain and Addiction-Center (CPA-C), University of Arizona Health Sciences, 85721, USA; The Center of Excellence in Addiction Studies (CEAS), University of Arizona, Tucson, Arizona, 85721, USA
| | - Todd W Vanderah
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA; Neuroscience Graduate Interdisciplinary Program, University of Arizona, Tucson, Arizona, 85721, USA; Comprehensive Pain and Addiction-Center (CPA-C), University of Arizona Health Sciences, 85721, USA; The Center of Excellence in Addiction Studies (CEAS), University of Arizona, Tucson, Arizona, 85721, USA
| | - Arthur C Riegel
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, 85721, USA; Neuroscience Graduate Interdisciplinary Program, University of Arizona, Tucson, Arizona, 85721, USA; Comprehensive Pain and Addiction-Center (CPA-C), University of Arizona Health Sciences, 85721, USA; The Center of Excellence in Addiction Studies (CEAS), University of Arizona, Tucson, Arizona, 85721, USA; Department of Neuroscience, College of Science, University of Arizona, Tucson, Arizona, 85721, USA; James C. Wyant College of Optical Sciences, the University of Arizona, Tucson, Arizona, 85721, USA.
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Raval NR, Johansen A, Donovan LL, Ros NF, Ozenne B, Hansen HD, Knudsen GM. A Single Dose of Psilocybin Increases Synaptic Density and Decreases 5-HT 2A Receptor Density in the Pig Brain. Int J Mol Sci 2021; 22:E835. [PMID: 33467676 PMCID: PMC7830000 DOI: 10.3390/ijms22020835] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 02/06/2023] Open
Abstract
A single dose of psilocybin, a psychedelic and serotonin 2A receptor (5-HT2AR) agonist, may be associated with antidepressant effects. The mechanism behind its antidepressive action is unknown but could be linked to increased synaptogenesis and down-regulation of cerebral 5-HT2AR. Here, we investigate if a single psychedelic dose of psilocybin changes synaptic vesicle protein 2A (SV2A) and 5-HT2AR density in the pig brain. Twenty-four awake pigs received either 0.08 mg/kg psilocybin or saline intravenously. Twelve pigs (n = 6/intervention) were euthanized one day post-injection, while the remaining twelve pigs were euthanized seven days post-injection (n = 6/intervention). We performed autoradiography on hippocampus and prefrontal cortex (PFC) sections with [3H]UCB-J (SV2A), [3H]MDL100907 (5-HT2AR antagonist) and [3H]Cimbi-36 (5-HT2AR agonist). One day post psilocybin injection, we observed 4.42% higher hippocampal SV2A density and lowered hippocampal and PFC 5-HT2AR density (-15.21% to -50.19%). These differences were statistically significant in the hippocampus for all radioligands and in the PFC for [3H]Cimbi-36 only. Seven days post-intervention, there was still significantly higher SV2A density in the hippocampus (+9.24%) and the PFC (+6.10%), whereas there were no longer any differences in 5-HT2AR density. Our findings suggest that psilocybin causes increased persistent synaptogenesis and an acute decrease in 5-HT2AR density, which may play a role in psilocybin's antidepressive effects.
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Affiliation(s)
- Nakul Ravi Raval
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Annette Johansen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Lene Lundgaard Donovan
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Nídia Fernandez Ros
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
| | - Brice Ozenne
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Department of Public Health, Section of Biostatistics, Faculty of Health and Medical Sciences, University of Copenhagen, 1014 Copenhagen, Denmark
| | - Hanne Demant Hansen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Gitte Moos Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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Tsybko AS, Ilchibaeva TV, Filimonova EA, Eremin DV, Popova NK, Naumenko VS. The Chronic Treatment With 5-HT 2A Receptor Agonists Affects the Behavior and the BDNF System in Mice. Neurochem Res 2020; 45:3059-3075. [PMID: 33095437 DOI: 10.1007/s11064-020-03153-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 09/13/2020] [Accepted: 10/15/2020] [Indexed: 01/09/2023]
Abstract
Serotonin 5-HT2A receptors and the brain-derived neurotrophic factor (BDNF) are involved in the pathophysiology and treatment of many psychiatric diseases. However, the interaction between 5-HT2A and BDNF is still poorly understood. In the present paper, the effects of chronic treatment with mixed 5-HT2A/2C receptor agonist DOI, highly selective 5-HT2A agonists TCB-2 and 25CN-NBOH on behavior and the BDNF system have been investigated. Chronic treatment of males of C57Bl/6 mice with DOI, TCB-2 and 25CN-NBOH (1 mg/kg, i.p., 14 days) resulted in desensitization of 5-HT2A receptors. Treatment with 25CN-NBOH significantly increased startle amplitude. At the same time all used drugs failed to affect anxiety, exploratory and stereotyped behavior as well as spatial memory and learning. TCB-2 and 25CN-NBOH increased the BDNF mRNA level. All 5-HT2A agonists increased the proBDNF level but failed to alter the mature BDNF protein level. TrkB and p75NTR mRNA levels were affected by all utilized agonists. All drugs decreased the total level as well as membrane TrkB protein one indicating downregulation of TrkB receptors. All agonists decreased the membrane p75NTR protein level. Thus, we have shown for the first time that the chronic activation of the 5-HT2A receptor with agonists has affected the BDNF system almost on all levels-transcription, proBDNF production, TrkB and p75NTR receptors' level. The obtained data suggested possible suppression in BDNF-TrkB signaling under chronic treatment with 5-HT2A agonists.
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Affiliation(s)
- Anton S Tsybko
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of Russian Academy of Sciences, Prospekt Lavrentyeva, 10, 630090, Novosibirsk, Russia.
| | - Tatiana V Ilchibaeva
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of Russian Academy of Sciences, Prospekt Lavrentyeva, 10, 630090, Novosibirsk, Russia
| | - Elena A Filimonova
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of Russian Academy of Sciences, Prospekt Lavrentyeva, 10, 630090, Novosibirsk, Russia
| | - Dmitry V Eremin
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of Russian Academy of Sciences, Prospekt Lavrentyeva, 10, 630090, Novosibirsk, Russia
| | - Nina K Popova
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of Russian Academy of Sciences, Prospekt Lavrentyeva, 10, 630090, Novosibirsk, Russia
| | - Vladimir S Naumenko
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of Russian Academy of Sciences, Prospekt Lavrentyeva, 10, 630090, Novosibirsk, Russia
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Custodio RJP, Sayson LV, Botanas CJ, Abiero A, You KY, Kim M, Lee HJ, Yoo SY, Lee KW, Lee YS, Seo J, Ryu IS, Kim HJ, Cheong JH. 25B-NBOMe, a novel N-2-methoxybenzyl-phenethylamine (NBOMe) derivative, may induce rewarding and reinforcing effects via a dopaminergic mechanism: Evidence of abuse potential. Addict Biol 2020; 25:e12850. [PMID: 31749223 DOI: 10.1111/adb.12850] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 10/08/2019] [Accepted: 10/14/2019] [Indexed: 01/26/2023]
Abstract
An increasing number of N-2-methoxybenzyl-phenethylamine (NBOMe) derivatives are being misused worldwide, including the potent hallucinogen 2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine (25B-NBOMe). However, the number of studies characterizing the abuse potential and psychopharmacological properties of 25B-NBOMe is limited; thus, we examined its rewarding and reinforcing effects using conditioned place preference (CPP) and self-administration (SA) tests. Pretreatment with SCH23390 (SCH), Haloperidol (HAL), and ketanserin (KS), antagonists of dopamine D1 (DRD1 ), dopamine D2 (DRD2 ), and serotonin 2A (5-HT2A receptor) receptors, respectively, was utilized during a CPP test to investigate the involvement of the dopaminergic and serotonergic systems in 25B-NBOMe-mediated effects. We also examined the effects of 25B-NBOMe on the expression of dopamine-related proteins in the nucleus accumbens (NAcc) and ventral tegmental area (VTA). Then, we measured the dopamine level, phosphorylated CREB (p-CREB), deltaFosB (ΔFosB), and brain-derived neurotrophic factor (BDNF) in the NAcc. In addition, we explored the involvement of 5-HT2A receptors in the 25B-NBOMe-induced head twitch response (HTR). We also examined the effects of 25B-NBOMe on brain wave activity using electroencephalography. 25B-NBOMe elicited CPP and SA. SCH and HAL blocked 25B-NBOMe-induced CPP, whereas KS did not. Moreover, 25B-NBOMe altered the DRD1 , DRD2 , and dopamine transporter expression and increased dopamine levels. It also induced changes in p-CREB, ΔFosB, and BDNF expression. 25B-NBOMe induced HTR and increased 5-HT2A receptor mRNA levels, effects inhibited by KS. Furthermore, 25B-NBOMe altered delta and gamma wave activity, which was normalized by SCH and HAL. These findings show that 25B-NBOMe may induce rewarding and reinforcing effects via a dopaminergic mechanism, suggesting its abuse potential.
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Affiliation(s)
- Raly James Perez Custodio
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Leandro Val Sayson
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Chrislean Jun Botanas
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Arvie Abiero
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Kyung Yi You
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Mikyung Kim
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Hyun Jun Lee
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Sung Yeun Yoo
- Medicinal Chemistry Laboratory, Department of Pharmacy and Department of Life and Nanopharmaceutical Sciences, College of Pharmacy Kyung Hee University Seoul Republic of Korea
| | - Kun Won Lee
- Medicinal Chemistry Laboratory, Department of Pharmacy and Department of Life and Nanopharmaceutical Sciences, College of Pharmacy Kyung Hee University Seoul Republic of Korea
| | - Yong Sup Lee
- Medicinal Chemistry Laboratory, Department of Pharmacy and Department of Life and Nanopharmaceutical Sciences, College of Pharmacy Kyung Hee University Seoul Republic of Korea
| | - Joung‐Wook Seo
- Center for Safety Pharmacology Korea Institute of Toxicology Daejeon Republic of Korea
| | - In Soo Ryu
- Center for Safety Pharmacology Korea Institute of Toxicology Daejeon Republic of Korea
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
| | - Jae Hoon Cheong
- Uimyung Research Institute for Neuroscience, College of Pharmacy Sahmyook University Seoul Republic of Korea
- School of Pharmacy Chonbuk National University Jeonju‐si Republic of Korea
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Castellanos JP, Woolley C, Bruno KA, Zeidan F, Halberstadt A, Furnish T. Chronic pain and psychedelics: a review and proposed mechanism of action. Reg Anesth Pain Med 2020; 45:486-494. [DOI: 10.1136/rapm-2020-101273] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/01/2020] [Accepted: 04/06/2020] [Indexed: 12/22/2022]
Abstract
The development of chronic pain is a complex mechanism that is still not fully understood. Multiple somatic and visceral afferent pain signals, when experienced over time, cause a strengthening of certain neural circuitry through peripheral and central sensitization, resulting in the physical and emotional perceptual chronic pain experience. The mind-altering qualities of psychedelics have been attributed, through serotonin 2A (5-HT2A) receptor agonism, to ‘reset’ areas of functional connectivity (FC) in the brain that play prominent roles in many central neuropathic states. Psychedelic substances have a generally favorable safety profile, especially when compared with opioid analgesics. Clinical evidence to date for their use for chronic pain is limited; however, several studies and reports over the past 50 years have shown potential analgesic benefit in cancer pain, phantom limb pain and cluster headache. While the mechanisms by which the classic psychedelics may provide analgesia are not clear, several possibilities exist given the similarity between 5-HT2A activation pathways of psychedelics and the nociceptive modulation pathways in humans. Additionally, the alterations in FC seen with psychedelic use suggest a way that these agents could help reverse the changes in neural connections seen in chronic pain states. Given the current state of the opioid epidemic and limited efficacy of non-opioid analgesics, it is time to consider further research on psychedelics as analgesics in order to improve the lives of patients with chronic pain conditions.
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Abiero A, Ryu IS, Botanas CJ, Custodio RJP, Sayson LV, Kim M, Lee HJ, Kim HJ, Seo JW, Cho MC, Lee KW, Yoo SY, Jang CG, Lee YS, Cheong JH. Four Novel Synthetic Tryptamine Analogs Induce Head-Twitch Responses and Increase 5-HTR2a in the Prefrontal Cortex in Mice. Biomol Ther (Seoul) 2019; 28:83-91. [PMID: 31230432 PMCID: PMC6939696 DOI: 10.4062/biomolther.2019.049] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/08/2019] [Accepted: 05/23/2019] [Indexed: 12/22/2022] Open
Abstract
Tryptamines are monoamine alkaloids with hallucinogenic properties and are widely abused worldwide. To hasten the regulations of novel substances and predict their abuse potential, we designed and synthesized four novel synthetic tryptamine analogs: Pyrrolidino tryptamine hydrochloride (PYT HCl), Piperidino tryptamine hydrochloride (PIT HCl), N,N-dibutyl tryptamine hydrochloride (DBT HCl), and 2-Methyl tryptamine hydrochloride (2-MT HCl). Then, we evaluated their rewarding and reinforcing effects using the conditioned place preference (CPP) and self-administration (SA) paradigms. We conducted an open field test (OFT) to determine the effects of the novel compounds on locomotor activity. A head-twitch response (HTR) was also performed to characterize their hallucinogenic properties. Lastly, we examined the effects of the compounds on 5-HTR1a and 5-HTR2a in the prefrontal cortex using a quantitative real-time polymerase chain reaction (qRT-PCR) assay. None of the compounds induced CPP in mice or initiated SA in rats. PYT HCl and PIT HCl reduced the locomotor activity and elevated the 5-HTR1a mRNA levels in mice. Acute and repeated treatment with the novel tryptamines elicited HTR in mice. Furthermore, a drug challenge involving a 7-day abstinence from drug use produced higher HTR than acute and repeated treatments. Both the acute treatment and drug challenge increased the 5-HTR2a mRNA levels. Ketanserin blocked the induced HTR. Taken together, the findings suggest that PYT HCl, PIT HCl, DBT HCl, and 2-MT HCl produce hallucinogenic effects via 5-HTR2a stimulation, but may have low abuse potential.
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Affiliation(s)
- Arvie Abiero
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - In Soo Ryu
- Center for Safety Pharmacology, Korea Institute of Toxicology, Daejeon 34114, Republic of Korea
| | - Chrislean Jun Botanas
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - Raly James Perez Custodio
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - Leandro Val Sayson
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - Mikyung Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - Hyun Jun Lee
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
| | - Joung-Wook Seo
- Center for Safety Pharmacology, Korea Institute of Toxicology, Daejeon 34114, Republic of Korea
| | - Min Chang Cho
- Medicinal Chemistry Laboratory, Department of Pharmacy & Department of Life and Nanopharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Kun Won Lee
- Medicinal Chemistry Laboratory, Department of Pharmacy & Department of Life and Nanopharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Sung Yeun Yoo
- Medicinal Chemistry Laboratory, Department of Pharmacy & Department of Life and Nanopharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yong Sup Lee
- Medicinal Chemistry Laboratory, Department of Pharmacy & Department of Life and Nanopharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Jae Hoon Cheong
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, Seoul 01795, Republic of Korea
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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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Abstract
The dorsal cochlear nucleus (DCN) is one of the first stations within the central auditory pathway where the basic computations underlying sound localization are initiated and heightened activity in the DCN may underlie central tinnitus. The neurotransmitter serotonin (5-hydroxytryptamine; 5-HT), is associated with many distinct behavioral or cognitive states, and serotonergic fibers are concentrated in the DCN. However, it remains unclear what is the function of this dense input. Using a combination of in vitro electrophysiology and optogenetics in mouse brain slices, we found that 5-HT directly enhances the excitability of fusiform principal cells via activation of two distinct 5-HT receptor subfamilies, 5-HT2A/2CR (5-HT2A/2C receptor) and 5-HT7R (5-HT7 receptor). This excitatory effect results from an augmentation of hyperpolarization-activated cyclic nucleotide-gated channels (Ih or HCN channels). The serotonergic regulation of excitability is G-protein-dependent and involves cAMP and Src kinase signaling pathways. Moreover, optogenetic activation of serotonergic axon terminals increased excitability of fusiform cells. Our findings reveal that 5-HT exerts a potent influence on fusiform cells by altering their intrinsic properties, which may enhance the sensitivity of the DCN to sensory input.
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Thompson PM, Cruz DA, Olukotun DY, Delgado PL. Serotonin receptor, SERT mRNA and correlations with symptoms in males with alcohol dependence and suicide. Acta Psychiatr Scand 2012; 126:165-74. [PMID: 22176604 DOI: 10.1111/j.1600-0447.2011.01816.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This study tested the hypothesis that abnormalities in components of the serotonin (5HT) system in the prefrontal cortex are associated with suicide in alcohol-dependent subjects. Second, we assessed the relationship of lifetime impulsivity and mood symptoms with prefrontal cortex 5-HT measures. METHOD Tissue was obtained from Brodmann's areas (BA) 9 and 24 in postmortem samples of individuals who were alcohol dependent with suicide (n = 5), alcohol dependent without suicide (n = 9) and normal controls (n = 5). Serotonin receptor (5HT) and serotonin reuptake transporter (SERT) mRNA were measured. Interviews with next of kin estimated lifetime impulsivity and mood symptoms in the last week of life. RESULTS Serotonin receptor 1A (5HT1A) mRNA in BA 9 was elevated in the alcohol dependence without suicide group compared with controls. In the alcohol dependence with suicide group, anxiety symptoms were associated with decreased BA 24 SERT mRNA and depressive symptoms with BA 9 5HT1A mRNA expression. In the alcohol dependent only group impulsivity is correlated with increased BA 9, and BA 24 serotonin receptor 2A mRNA. CONCLUSION Our data suggest region-specific change, rather than global serotonin blunting is involved in alcohol dependence and suicide. It also suggests that symptoms are differentially influenced by prefrontal cortex serotonin receptor mRNA levels.
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Affiliation(s)
- P M Thompson
- Department of Psychiatry, University of Texas Health Science Center San Antonio Southwest Brain Bank, USA.
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Naumenko VS, Tsybko AS, Bazovkina DV, Popova NK. Involvement of 5-HT2A receptors in genetic mechanisms of autoregulation of brain 5-HT system. Mol Biol 2012. [DOI: 10.1134/s0026893312020100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Nijenhuis CM, Horst PGJT, Berg LTWDJVD, Wilffert B. Disturbed development of the enteric nervous system after in utero exposure of selective serotonin re-uptake inhibitors and tricyclic antidepressants. Part 1: Literature review. Br J Clin Pharmacol 2012; 73:16-26. [PMID: 21815911 DOI: 10.1111/j.1365-2125.2011.04075.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The increase in selective serotonin re-uptake inhibitor (SSRI) use during pregnancy, questions concerning abnormal development of the enteric nervous system (ENS), increase in laxative use in children and the association of fluoxetine with infantile hypertrophic pyloric stenosis (IHPS) gave rise to this pharmacological literature review. The role of 5-HT and the NE uptake in ontogeny of the ENS and the effects SSRIs and TCAs might have on the development of the ENS were investigated. The literature study showed that SSRIs may influence the development of the ENS in two ways. Blockage of the serotonin re-uptake transporter (SERT) during foetal development could influence migration, differentiation and survival of cells. This could lead to abnormal development in the first trimester of pregnancy. The other way is that 5-HT seems to be a growth factor in the primitive ENS. This growth factor like action is mediated through the 5-HT(2B) receptor and stimulation of this receptor by SSRIs influences the fate of late-developing enteric neurons. This could lead to abnormal development in the second and third trimester. TCAs could influence the development of the ENS, besides through inhibition of the SERT, through inhibition of the norepinephrine transporter (NET). Expression of the NET seems to be essential for a full development of enteric neurons and especially for serotonergic neurons. In addition the NET was detected early in ontogeny and precedes neuronal differentiation, which suggests that TCAs might influence development of the ENS when exposed early in pregnancy. The insights of this study gave rise to hypotheses which will be tested in an epidemiological cohort study.
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Affiliation(s)
- Cynthia M Nijenhuis
- Department of Pharmaco-epidemiology and Pharmaco-economy, University of Groningen, Groningen, The Netherlands
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13
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Dougherty JP, Aloyo VJ. Pharmacological and behavioral characterization of the 5-HT2A receptor in C57BL/6N mice. Psychopharmacology (Berl) 2011; 215:581-93. [PMID: 21340474 DOI: 10.1007/s00213-011-2207-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 01/27/2011] [Indexed: 11/30/2022]
Abstract
RATIONALE The serotonin (5-HT) 2A receptor is implicated in numerous psychiatric disorders, making it an important, clinically relevant target. Despite the availability of transgenic mouse lines, the native mouse 5-HT(2A) receptor is not well-characterized. OBJECTIVES The goals of the current study were to determine 5-HT(2A) and 5-HT(2C) receptor densities in mouse cortex, establish a pharmacological profile of the mouse 5-HT(2A) receptor, and determine the effects of chronic drug treatment on 5-HT(2A) receptor density and 5-HT(2A) receptor-mediated behavior. METHODS Receptor densities were determined in cortex and frontal cortex via saturation binding assays using [(3)H]ketanserin or [(3)H]mesulergine. A pharmacological profile was established by displacing [(3)H]ketanserin binding with several ligands. Chronic treatment with 5-HT(2A/2C) receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI), 5-HT(2A) receptor antagonist, MDL 11939, or vehicle was followed by 5-HT(2A) receptor density determination. Head twitch responses (HTRs) were counted on select days. RESULTS Mice had high 5-HT(2A), but low 5-HT(2C) receptor densities. Ligand binding affinities for mouse 5-HT(2A) receptors correlated with rat, but not rabbit or human, affinities. Chronically DOI-treated mice displayed reduced HTRs and 5-HT(2A) receptor density compared to saline-treated mice. Receptor density was unchanged following chronic treatment with MDL 11939. CONCLUSIONS The current study provides some basic information about mouse 5-HT(2A) and 5-HT(2C) receptors and provides comparisons to rats, rabbits, and humans. The current chronic agonist treatment study demonstrated an important similarity between the 5-HT(2A) receptor in mice, rats, and rabbits, while antagonist treatment revealed an interesting difference from previous studies in rabbits.
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Affiliation(s)
- John P Dougherty
- Drexel University College of Medicine, Philadelphia, PA 19102, USA.
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15
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Stress impairs 5-HT2A receptor-mediated serotonergic facilitation of GABA release in juvenile rat basolateral amygdala. Neuropsychopharmacology 2009; 34:410-23. [PMID: 18536707 DOI: 10.1038/npp.2008.71] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The occurrence of stress and anxiety disorders has been closely associated with alterations of the amygdala GABAergic system. In these disorders, dysregulation of the serotonergic system, a very important modulator of the amygdala GABAergic system, is also well recognized. The present study, utilizing a learned helplessness stress rat model, was designed to determine whether stress is capable of altering serotonergic modulation of the amygdala GABAergic system. In control rats, administration of 5-HT or alpha-methyl-5-HT, a 5-HT(2) receptor agonist, to basolateral amygdala (BLA) slices dramatically enhanced frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). This effect was blocked by selective 5-HT(2A) receptor antagonists while a selective 5-HT(2B) receptor agonist and a selective 5-HT(2C) receptor agonist were without effect on sIPSCs. Double immunofluorescence labeling demonstrated that the 5-HT(2A) receptor is primarily localized to parvalbumin-containing BLA interneurons. Thus, serotonin primarily acts via 5-HT(2A) receptors to facilitate BLA GABAergic inhibition. In stressed rats, the 5-HT(2A) receptor-mediated facilitative actions were severely impaired. Quantitative RT-PCR and western blot analysis showed that the impairment of 5-HT(2A) receptor signaling primarily resulted from receptor downregulation. The stress-induced effect appeared to be specific to 5-HT(2A) receptors because stress had no significant impact on other serotonin receptors, as well as histamine H(3) receptor and alpha(2) adrenoceptor signaling in the BLA. This severe impairment of 5-HT(2A) receptor-mediated facilitation of BLA GABAergic inhibition might result in an amygdala circuitry with hyperexcitability, and a lower threshold of activation, and thus be an important mechanism underlying the emergence of stress-associated psychiatric symptoms.
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16
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Muma NA, Singh RK, Vercillo MS, D'Souza DN, Zemaitaitis B, Garcia F, Damjanoska KJ, Zhang Y, Battaglia G, Van de Kar LD. Chronic olanzapine activates the Stat3 signal transduction pathway and alters expression of components of the 5-HT2A receptor signaling system in rat frontal cortex. Neuropharmacology 2007; 53:552-62. [PMID: 17675105 PMCID: PMC2075101 DOI: 10.1016/j.neuropharm.2007.06.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/12/2007] [Accepted: 06/20/2007] [Indexed: 12/19/2022]
Abstract
The mechanisms underlying desensitization of serotonin 2A (5-HT(2A)) receptor signaling by antagonists are unclear but may involve changes in gene expression mediated via signal transduction pathways. In cells in culture, olanzapine causes desensitization of 5-HT(2A) receptor signaling and increases the levels of regulators of G protein signaling (RGS) 7 protein dependent on phosphorylation/activation of the Janus kinase 2 (Jak2)/signal transducers and activators of transcription 3 (Stat3) signaling pathway. In the current study, the 5-HT(2A) receptor signaling system in rat frontal cortex was examined following 7 days of daily treatment with 0.5, 2.0 or 10.0 mg/kg i.p. olanzapine. Olanzapine increased phosphorylation of Stat3 in rats treated daily with 10 mg/kg olanzapine and caused a dose-dependent desensitization of 5-HT(2A) receptor-mediated phospholipase C activity. There were dose-dependent increases in the levels of membrane-associated 5-HT(2A) receptor, G(alpha11) and G(alphaq) protein levels but no changes in the G(beta) protein levels. With olanzapine treatment, RGS4 protein levels increase in the membrane-fraction and decrease in the cytosolic fraction by similar amounts suggesting a redistribution of RGS4 protein within neurons. RGS7 protein levels increase in both the membrane and cytosolic fractions in rats treated daily with 10mg/kg olanzapine. The olanzapine-induced increase in Stat3 activity could underlie the increase in RGS7 protein expression in vivo as previously demonstrated in cultured cells. Furthermore, the increases in membrane-associated RGS proteins could play a role in desensitization of signaling by terminating the activated G(alphaq/11) proteins more rapidly.
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Affiliation(s)
- N A Muma
- Department of Pharmacology, Loyola University Medical Center, Maywood, IL 60153, USA.
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17
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Shi J, Damjanoska KJ, Singh RK, Carrasco GA, Garcia F, Grippo AJ, Landry M, Sullivan NR, Battaglia G, Muma NA. Agonist Induced-Phosphorylation of Gα11Protein Reduces Coupling to 5-HT2AReceptors. J Pharmacol Exp Ther 2007; 323:248-56. [PMID: 17646429 DOI: 10.1124/jpet.107.122317] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously demonstrated that 24-h treatment with (-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI) causes phosphorylation of Galpha11 protein at serine 154 and that this phosphorylation causes desensitization of serotonin (5-HT) 2A receptor signaling in A1A1v cells (Shi et al., 2007). We now report that treatment of A1A1v cells with DOI for 24 h produces a greater reduction in the Bmax of [125I](+/-)-DOI-labeled high-affinity binding sites (46%) than the reduction of [3H]ketanserin binding sites (25%). Although the KD values are not altered, there is a smaller amount of GTPgammaS [guanosine 5'-3-O-(thio)triphosphate]-sensitive [125I](+/-)-DOI binding in DOI-treated cells. These results suggest that DOI treatment causes down-regulation of 5-HT2A receptors and reductions in G protein-coupled 5-HT2A receptors. In contrast, in cells transfected with the phosphorylation state mimic G(alpha11)S154D, GTPgammaS-sensitive [125I](+/-)-DOI binding was decreased by 48%; however, there was no significant difference in the KD and Bmax values of [125I](+/-)-DOI-labeled receptors. The receptor binding experiments suggest that phosphorylation of Galpha11 on serine 154 reduces coupling of 5-HT2A receptors, whereas DOI causes down-regulation of 5-HT2A receptors in addition to the phosphorylation-induced uncoupling of Galpha11 to 5-HT2A receptors. To determine whether DOI increases phosphorylation of Galphaq/11 protein in vivo, rats were treated with 1 mg/kg/day DOI or saline for 1 to 7 days. Seven days of DOI treatment significantly decreased phospholipase C activity stimulated by an Emax concentration of 5-HT by 40% and increased phosphorylation of Galphaq/11 proteins by 51% in the frontal cortex. These data suggest that DOI causes phosphorylation of Galphaq/11 in vivo and could thereby contribute to the desensitization of 5-HT2A receptors.
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Affiliation(s)
- Ju Shi
- Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA
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18
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Cheung THC, Bezzina G, Body S, Fone KCF, Bradshaw CM, Szabadi E. Tolerance to the effect of 2,5-dimethoxy-4-iodoamphetamine (DOI) on free-operant timing behaviour: interaction between behavioural and pharmacological mechanisms. Psychopharmacology (Berl) 2007; 192:521-35. [PMID: 17333133 DOI: 10.1007/s00213-007-0743-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 02/09/2007] [Indexed: 12/25/2022]
Abstract
RATIONALE The psychostimulant d-amphetamine, the D(2/3) dopamine receptor agonist quinpirole and the 5-HT(2) receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) have similar effects on free-operant timing behaviour. There is evidence that tolerance develops to the effects of psychostimulants on timing performance during chronic treatment; this tolerance is generally attributed to behavioural adaptation rather than to pharmacological desensitisation. There have been no previous investigations of tolerance to the effect of DOI on free-operant timing behaviour. OBJECTIVE To demonstrate tolerance to DOI's effect on timing performance and to examine the nature of this tolerance. MATERIALS AND METHODS Rats were trained under the free-operant psychophysical procedure to press two levers (A and B) in 80-s trials in which reinforcement was provided intermittently for responding on A in the first half and B in the second half of the trial. Percent responding on B (%B) was recorded in successive 8-s epochs of the trials; logistic functions were fitted to the data from each rat for the derivation of timing indices (T (50) [time corresponding to %B = 50]; Weber fraction). RESULTS In experiment 1, DOI (0.25 mg kg(-1)) reduced T (50) compared to vehicle; tolerance to this effect was seen after repeated daily treatments with DOI if the rats were exposed to behavioural training during the period of treatment but not if the repeated treatments took place during a 'holiday' from behavioural training. In experiment 2, repeated treatment with DOI resulted in tolerance to the effect of DOI on T (50) and cross-tolerance to the effect of d-amphetamine (0.4 mg kg(-1)), but no cross-tolerance was seen to the effect of quinpirole (0.08 mg kg(-1)). CONCLUSIONS The results indicate that behavioural adaptation is involved in the development of tolerance to DOI's effect on timing. The finding of cross-tolerance to d-amphetamine but not to quinpirole suggests that the reduction of T (50) in the free-operant psychophysical procedure may be brought about by two distinct pharmacological mechanisms, one activated by DOI and d-amphetamine, and the other by quinpirole.
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Affiliation(s)
- T H C Cheung
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, UK.
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19
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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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20
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Urban JD, Clarke WP, von Zastrow M, Nichols DE, Kobilka B, Weinstein H, Javitch JA, Roth BL, Christopoulos A, Sexton PM, Miller KJ, Spedding M, Mailman RB. Functional selectivity and classical concepts of quantitative pharmacology. J Pharmacol Exp Ther 2006; 320:1-13. [PMID: 16803859 DOI: 10.1124/jpet.106.104463] [Citation(s) in RCA: 830] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The concept of intrinsic efficacy has been enshrined in pharmacology for half of a century, yet recent data have revealed that many ligands can differentially activate signaling pathways mediated via a single G protein-coupled receptor in a manner that challenges the traditional definition of intrinsic efficacy. Some terms for this phenomenon include functional selectivity, agonist-directed trafficking, and biased agonism. At the extreme, functionally selective ligands may be both agonists and antagonists at different functions mediated by the same receptor. Data illustrating this phenomenon are presented from serotonin, opioid, dopamine, vasopressin, and adrenergic receptor systems. A variety of mechanisms may influence this apparently ubiquitous phenomenon. It may be initiated by differences in ligand-induced intermediate conformational states, as shown for the beta(2)-adrenergic receptor. Subsequent mechanisms that may play a role include diversity of G proteins, scaffolding and signaling partners, and receptor oligomers. Clearly, expanded research is needed to elucidate the proximal (e.g., how functionally selective ligands cause conformational changes that initiate differential signaling), intermediate (mechanisms that translate conformation changes into differential signaling), and distal mechanisms (differential effects on target tissue or organism). Besides the heuristically interesting nature of functional selectivity, there is a clear impact on drug discovery, because this mechanism raises the possibility of selecting or designing novel ligands that differentially activate only a subset of functions of a single receptor, thereby optimizing therapeutic action. It also may be timely to revise classic concepts in quantitative pharmacology and relevant pharmacological conventions to incorporate these new concepts.
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MESH Headings
- Animals
- Humans
- Ligands
- Protein Conformation
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/physiology
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/physiology
- Receptors, Dopamine D1/chemistry
- Receptors, Dopamine D1/drug effects
- Receptors, Dopamine D1/physiology
- Receptors, Dopamine D2/chemistry
- Receptors, Dopamine D2/drug effects
- Receptors, Dopamine D2/physiology
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/physiology
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/physiology
- Receptors, Vasopressin/chemistry
- Receptors, Vasopressin/drug effects
- Receptors, Vasopressin/physiology
- Signal Transduction
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Affiliation(s)
- Jonathan D Urban
- Curriculum in Toxicology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7160, USA
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21
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Marek GJ, Wright RA, Schoepp DD. 5-Hydroxytryptamine2A (5-HT2A) receptor regulation in rat prefrontal cortex: interaction of a phenethylamine hallucinogen and the metabotropic glutamate2/3 receptor agonist LY354740. Neurosci Lett 2006; 403:256-60. [PMID: 16759803 DOI: 10.1016/j.neulet.2006.05.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 04/23/2006] [Accepted: 05/02/2006] [Indexed: 02/08/2023]
Abstract
5-Hydroxytryptamine2A (5-HT2A) receptor regulation is atypical compared to most other monoaminergic receptors in that chronic administration of both antagonists and agonists results in down-regulation of cortical 5-HT2A receptor number and the functional in vitro and in vivo effects. We have recently found that midline thalamic lesions, which appeared to block glutamate release induced by activation of 5-HT2A receptors, also increased 5-HT2A receptor binding in layers I and Va of the medial prefrontal cortex (mPFC). These layers contain the highest density of both 5-HT2A receptors and thalamocortical terminals from the midline and intralaminar thalamic nuclei. These findings suggest the hypothesis that excitatory amino acid release plays a role in regulation of postsynaptic 5-HT2A receptors, and that down-regulation of 5-HT2A receptors by 5-HT2A agonists may not be attributed only to simple occupancy of the receptor by direct agonists. Therefore, we examined the effect of a single 30 min pretreatment with the metabotropic glutamate2/3 (mGlu2/3) receptor agonist (1S,2S,5R,6S)-2-aminobicyclo[3.1.0] hexane-2,6-dicarboxylate monohydrate (LY354740; 10 mg/kg, i.p.) on the second of three consecutive days of 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI) treatment (1.25 mg/kg, i.p.). The subchronic DOI administration significantly decreased binding of [125I]DOI to 5-HT2A receptors in layers I and Va of the mPFC by approximately 25%. In contrast, a single dose of LY354740 on Day 2 of this regimen completely blocked the DOI-induced down-regulation. Thus, a presumed hypoglutamatergic state secondary to thalamic lesions and increased glutamate release induced by a subchronic regimen of a 5-HT2A agonist (and hallucinogenic drug) differentially regulate prefrontal cortical 5-HT2A receptor binding.
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Affiliation(s)
- Gerard J Marek
- Yale School of Medicine, Department of Psychiatry, New Haven, CT 06508, USA.
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22
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Damjanoska KJ, Heidenreich BA, Kindel GH, D'Souza DN, Zhang Y, Garcia F, Battaglia G, Wolf WA, Van de Kar LD, Muma NA. Agonist-Induced Serotonin 2A Receptor Desensitization in the Rat Frontal Cortex and Hypothalamus. J Pharmacol Exp Ther 2004; 309:1043-50. [PMID: 14976228 DOI: 10.1124/jpet.103.062067] [Citation(s) in RCA: 18] [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
This study examined the time course and possible mechanisms of agonist-induced desensitization of 5-hydroxytryptamine serotonin 2A receptors in the rat frontal cortex and hypothalamic paraventricular nucleus after 1, 4, and 7 days of treatment with (-)-1-(2,5-dimethoxy-4-iodophenyl)2-aminopropane HCl [(-)-DOI] (1 mg/kg i.p.), a selective 5-HT(2A/2C) receptor agonist. In the frontal cortex, 5-HT-mediated phospholipase C (PLC) enzyme activity decreased by 24 to 30% after 4 to 7 days of (-)-DOI treatment without any significant changes in the guanosine 5'-3-O-(thio)triphosphate-mediated PLC enzyme activity. Additionally, treatment with (-)-DOI did not significantly change the levels of G(alpha11), regulator of G protein signaling (RGS)4, or RGS7 proteins in the frontal cortex, whereas G(alphaq) protein levels in the frontal cortex decreased (47%) only after 7 daily (-)-DOI injections. The functional status of 5-HT(2A) receptors in the hypothalamic paraventricular nucleus was examined using 5-HT(2A) receptor-mediated increases in plasma hormone levels. Plasma adrenocorticotrophic hormone (ACTH) and oxytocin measurements showed that 5-HT(2A) receptor desensitization began after only 1 day of (-)-DOI treatment, and the desensitization continued to increase after 4 and 7 days of treatment (ACTH response decreased 64.2-67.7%; oxytocin response decreased 82.3-90.1%). There were no significant alterations in levels of G(alphaq) or G(alpha11) lamic paraventricular proteins in the hypothanucleus. In conclusion, these results suggest that chronically administered (-)-DOI induces desensitization of 5-HT(2A) receptors in vivo, via a reduction in the ability of 5-HT(2A) receptors to activate G proteins without consistently altering levels of G(alpha) proteins or RGS proteins.
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Affiliation(s)
- K J Damjanoska
- Center for Serotonin Disorders Research, Department of Pharmacology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Ave., Maywood, IL 60153, USA
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23
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Enguix MJ, Sánchez L, Villazón M, Brea J, Tristán H, Caruncho HJ, Cadavid MI, Loza MI. Differential regulation of rat peripheral 5-HT(2A) and 5-HT(2B) receptor systems: influence of drug treatment. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2003; 368:79-90. [PMID: 12861437 DOI: 10.1007/s00210-003-0775-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2002] [Accepted: 05/08/2003] [Indexed: 10/26/2022]
Abstract
Most studies of 5-HT(2) receptor regulation have been carried out on the central nervous system (CNS) (which expresses 5-HT(2A) and 5-HT(2C) receptors); very few in vitro studies have addressed the peripheral receptors 5-HT(2A) and 5-HT(2B). The aim of this investigation was to compare the possible short- and long-term processes regulating these peripheral receptors in the rat. The in vitro contractile response elicited by serotonin (5-HT, 10 micro M) in the rat gastric fundus (5-HT(2B) receptor system) was rapid and followed by a partial fade to a steady state, in contrast with the rat thoracic aorta response (5-HT(2A) receptor system), which was more stable, slower and sustained. To characterize drug-receptor interactions, cumulative concentration/response curves (CCRCs) for 5-HT were constructed ex vivo for rat tissues treated with drugs acting at these receptors. Rats were examined 4 or 24 h after a single, i.p. administration of (+/-)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(+/-)DOI, 1 or 2.5 mg/kg], clozapine, cyproheptadine or rauwolscine (10 mg/kg), 48 h after a single i.p. administration of (+/-)DOI (2.5 mg/kg), clozapine or cyproheptadine (10 mg/kg) or 24 h after the last of with 15 daily i.p. administrations of (+/-)DOI (1 or 2.5 mg/kg), clozapine, cyproheptadine or rauwolscine (10 mg/kg). In the aorta, E(max) (the maximum response elicited by 5-HT) was unchanged 4 h after a single dose of any of the drugs tested. However, 24 h after a single dose, E(max) was lower in animals treated with (+/-)DOI (2.5 mg/kg), clozapine or cyproheptadine than in controls, whilst 48 h after a single dose of (+/-)DOI (2.5 mg/kg), clozapine or cyproheptadine there was no difference in E(max) between experimental and control animals. After chronic treatment with (+/-)DOI (2.5 mg/kg), clozapine and cyproheptadine, E(max) was lower than in controls. In the gastric fundus, E(max) 4 h after a single dose of each drug was lower than in controls, and the response recovered by 24 or 48 h. Following chronic treatment, E(max) was significantly lower than in controls for each drug used. These findings suggest first, that regulation of peripheral 5-HT(2) receptors (5-HT(2A) and 5-HT(2B)) is a functionally significant phenomenon in vivo, and occurs after administration of both agonists and antagonists. Second, the kinetics of peripheral 5-HT(2) receptor regulation were similar in both in vivo and ex vivo experiments. The 5-HT(2B) receptors in rat gastric fundus are more sensitive to drug-induced regulation than the 5-HT(2A) rat aortic receptors. Finally, long-term regulation of both receptors stabilizes short-term desensitization for longer.
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MESH Headings
- Amphetamines/pharmacology
- Animals
- Antipsychotic Agents/pharmacology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/physiology
- Clozapine/pharmacology
- Cyproheptadine/pharmacology
- Gastric Fundus/drug effects
- Gastric Fundus/metabolism
- Gastric Fundus/physiology
- In Vitro Techniques
- Ligands
- Male
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Muscle, Smooth/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2B/drug effects
- Receptor, Serotonin, 5-HT2B/metabolism
- Serotonin/metabolism
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Yohimbine/pharmacology
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Affiliation(s)
- M J Enguix
- School of Pharmacy, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain
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24
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Abstract
Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.
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Affiliation(s)
- Mark J Millan
- Psychopharmacology Department, Centre de Rescherches de Croissy, Institut de Recherches (IDR) Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, Paris, France.
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25
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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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26
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Qu Y, Chang L, Klaff J, Balbo A, Rapoport SI. Imaging brain phospholipase A2 activation in awake rats in response to the 5-HT2A/2C agonist (+/-)2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI). Neuropsychopharmacology 2003; 28:244-52. [PMID: 12589377 DOI: 10.1038/sj.npp.1300022] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Incorporation coefficients k(*) of intravenously injected [(3)H]arachidonic acid from blood into brain reflect the release from phospholipids of arachidonic acid by receptor-initiated activation of phospholipase A(2) (PLA(2)). In unanesthetized adult rats, 2.5 mg/kg intraperitoneally (i.p.) (+/-)2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI), which is a 5-HT(2A/2C) receptor agonist, has been reported to produce the behavioral changes of what is known as the 5-HT(2) syndrome, but only a few small regional decrements in brain glucose metabolism. In this study, 2.5 mg/kg i.p. DOI, when administered to unanesthetized rats, produced widespread and significant increases, of the order of 60%, in k(*) for arachidonate, particularly in neocortical brain regions reported to have high densities of 5-HT(2A) receptors. The increases could be entirely blocked by chronic pretreatment with mianserin, a 5-HT(2) receptor antagonist. The results suggest that the 5-HT(2) syndrome involves widespread brain activation of PLA(2) via 5-HT(2A) receptors, leading to the release of the second messenger, arachidonic acid. Chronic mianserin, a 5-HT(2) antagonist, prevents this activation.
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Affiliation(s)
- Ying Qu
- Brain Physiology and Metabolism Section, National Institute of Aging, National Institute of Health, Bethesda, MD 20892, USA.
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27
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Van Oekelen D, Megens A, Meert T, Luyten WHML, Leysen JE. Role of 5-HT(2) receptors in the tryptamine-induced 5-HT syndrome in rats. Behav Pharmacol 2002; 13:313-8. [PMID: 12218512 DOI: 10.1097/00008877-200207000-00008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We distinguished the functions of the different 5-hydroxytryptamine-2 (5-HT(2)) receptor (5-HT(2)R) subtypes in the tryptamine-induced 5-HT syndrome in rats using (1) the 5-HT(2A)R antagonist R93274 (N-[(3-p-fluorophenyl-1-propyl)-4-methyl-4-piperidinyl]-4-amino-5-iodo-2-methoxybenzamide), the 5-HT(2A/C)R antagonist R99647 (2-(dimethylaminomethyl)2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine), the 5-HT(2B/C)R antagonist SB-242084 (6-chloro-5-methyl-1-[[2-[(2-methyl-3-pyridyl)oxy]-5-pyridyl]carbamoyl]-indoline), and several 5-HT(2)R antagonists (ketanserin, risperidone, pipamperone and mianserin); and (2) chronic 5-HT(2)R activation by 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM). In contrast to SB-242084, the selective 5-HT(2A)R antagonist R93274 as well as the non-selective 5-HT(2A)R antagonists (R99647, ketanserin, risperidone, pipamperone and mianserin) significantly inhibited tryptamine-induced forepaw treading and tremors, and reversed peripherally mediated cyanosis into hyperaemia; only the 5-HT(2A/C)R antagonists R99647 and mianserin inhibited the tryptamine-induced hunched back. Intermittent DOM administration (intravenously every 48 h for 12 days) did not change the centrally mediated tryptamine-induced forepaw treading, tremors and hunched back at 1, 4 or 7 days after the last DOM pretreatment. The DOM-induced head twitch response, measured immediately after every DOM injection, was not affected. In contrast, peripherally mediated cyanosis was reversed into hyperaemia in 75, 11 and 20% of all pretreated rats at 1, 4 and 7 days, respectively, after the last DOM administration. Taken together, these finding suggest that central 5-HT(2A)Rs mediate tryptamine-induced forepaw treading and tremors, that peripheral 5-HT Rs mediate tryptamine-induced cyanosis, and that 5-HT(2A)Rs mediate tryptamine-induced hunched back. Peripheral 5-HT(2C)Rs are more sensitive to desensitization after intermittent treatment with an agonist than central 5-HT(2A)Rs.
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MESH Headings
- DOM 2,5-Dimethoxy-4-Methylamphetamine/pharmacology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Brain/drug effects
- Brain/metabolism
- Male
- Rats
- Rats, Wistar
- Receptor, Serotonin, 5-HT2A
- Receptor, Serotonin, 5-HT2B
- Receptor, Serotonin, 5-HT2C
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
- Serotonin Antagonists/administration & dosage
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Serotonin Syndrome/chemically induced
- Serotonin Syndrome/metabolism
- Tryptamines
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Affiliation(s)
- D Van Oekelen
- Discovery Research, Janssen Research Foundation, Beerse, Belgium
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28
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Birzniece V, Johansson IM, Wang MD, Bäckström T, Olsson T. Ovarian hormone effects on 5-hydroxytryptamine(2A) and 5-hydroxytryptamine(2C) receptor mRNA expression in the ventral hippocampus and frontal cortex of female rats. Neurosci Lett 2002; 319:157-61. [PMID: 11834317 DOI: 10.1016/s0304-3940(01)02570-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Alterations in female gonadal hormones are associated with anxiety and mood changes. The aim of the present study was to determine influences of chronic gonadal hormone supplementation on 5-HT(2A) and 5-HT(2C) receptor mRNA levels in the ventral hippocampus and the frontal cerebral cortex. Ovariectomized adult female Sprague-Dawley rats (n=37) received implantation of subcutaneous pellets containing different dosages of 17beta-estradiol alone or in combination with progesterone, or placebo pellets, for 2 weeks. Serotonin receptor mRNA levels were analyzed by in situ hybridization in the ventral hippocampus and 5-HT(2A) receptor mRNA also in the frontal cortex. Estradiol treatment in combination with low-dose progesterone increased 5-HT(2A) receptor mRNA by 43% in the CA2 region of the ventral hippocampus, while estradiol combined with high-dose progesterone increased the expression of this gene by 84% in ventral CA1. 5-HT(2A) mRNA expression in the frontal cortex was not influenced by hormone manipulation. 5-HT(2C) receptor gene expression was in the ventral hippocampus decreased in the CA2, ventral CA1 and the subiculum subregions by high-dose estradiol treatment (8-20% decreases). Effects on mood by gonadal hormones can be mediated, at least partly, through influences on 5-HT(2A) and 5-HT(2C) receptor expression.
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Affiliation(s)
- Vita Birzniece
- Department of Public Health and Clinical Medicine, Umeå University Hospital, Sweden.
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29
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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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30
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Anji A, Sullivan Hanley NR, Kumari M, Hensler JG. The role of protein kinase C in the regulation of serotonin-2A receptor expression. J Neurochem 2001; 77:589-97. [PMID: 11299321 DOI: 10.1046/j.1471-4159.2001.00261.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have investigated in C6 glioma cells the involvement of protein kinase C (PKC) in the regulation of serotonin-(2A) receptor (5-HT(2A) receptor) expression by agonist treatment. Comparison of the time-courses of agonist-induced downregulation of receptor number and mRNA indicate that a decrease in the number of 5-HT(2A) receptor binding sites in response to serotonin (5-HT) treatment is preceded by a decrease in 5-HT(2A) receptor mRNA. This decrease in 5-HT(2A) receptor mRNA as a result of agonist exposure was not due to a change in the stability or half-life of the transcript. Pretreatment of cells with the PKC inhibitor bisindolylmaleimide blocked the decrease in 5-HT(2A) receptor mRNA levels, and attenuated the down-regulation of 5-HT(2A) receptor binding sites induced by treatment with 5-HT. Experiments performed with the PKC inhibitors calphostin C and Gö 6976 confirmed that PKC was involved in the regulation of 5-HT(2A) receptor mRNA by agonist and implicate the conventional subgroup of PKC isoforms. Western blot analysis, using isoform-specific anti-PKC antibodies showed that under our culture conditions C6 glioma cells express the conventional isoforms PKC alpha, PKC gamma, as well as the novel isoforms PKC delta, PKC epsilon, and the atypical isoforms PKC lambda and PKC iota. Upon treatment with 5-HT for 10 min levels of the conventional isoforms PKC alpha and PKC gamma increased in the nuclear fraction. Taken together, our results implicate PKC alpha and/or PKC gamma in the regulation of 5-HT(2A) mRNA receptor and binding sites in response to agonist treatment.
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Affiliation(s)
- A Anji
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, Texas, USA
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