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Wang X, Yi R, Liang X, Zhang N, Zhong F, Lu Y, Chen W, Yu T, Zhang L, Wang H, Zhou L. Myelin modulates the process of isoflurane anesthesia through the regulation of neural activity. CNS Neurosci Ther 2024; 30:e14922. [PMID: 39138640 PMCID: PMC11322027 DOI: 10.1111/cns.14922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 07/01/2024] [Accepted: 08/04/2024] [Indexed: 08/15/2024] Open
Abstract
AIMS The mechanism underlying the reversible unconsciousness induced by general anesthetics (GA) remains unclear. Recent studies revealed the critical roles of myelin and oligodendrocytes (OLs) in higher functions of the brain. However, it is unknown whether myelin actively participates in the regulation of GA. The aim of this study is to investigate the roles and possible mechanisms of myelin in the regulation of consciousness alterations induced by isoflurane anesthesia. METHODS First, demyelination models for the entire brain and specific neural nuclei were established to investigate the potential role of myelination in the regulation of GA, as well as its possible regional specificity. c-Fos staining was then performed on the demyelinated nuclei to verify the impact of myelin loss on neuronal activity. Finally, the activity of neurons during isoflurane anesthesia in demyelinated mice was recorded by optical fiber photometric calcium signal. The related behavioral indicators and EEG were recorded and analyzed. RESULTS A prolonged emergence time was observed from isoflurane anesthesia in demyelinated mice, which suggested the involvement of myelin in regulating GA. The demyelination in distinct nuclei by LPC further clarified the region-specific roles of isoflurane anesthesia regulation by myelin. The effect of demyelination on isoflurane anesthesia in the certain nucleus was consistent with that in neurons towards isoflurane anesthesia. Finally, we found that the mechanism of myelin in the modulation of isoflurane anesthesia is possibly through the regulation of neuronal activity. CONCLUSIONS In brief, myelin in the distinct neural nucleus plays an essential role in regulating the process of isoflurane anesthesia. The possible mechanism of myelin in the regulation of isoflurane anesthesia is neuronal activity modification by myelin integrity during GA. Our findings enhanced the comprehension of myelin function, and offered a fresh perspective for investigating the neural mechanisms of GA.
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Affiliation(s)
- Xu Wang
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
| | - Rulan Yi
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Xiaoling Liang
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
| | - Ning Zhang
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
| | - Fuwang Zhong
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
| | - Yali Lu
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
| | - Wenjia Chen
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
| | - Tian Yu
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Linyong Zhang
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Haiying Wang
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Liang Zhou
- Key Laboratory of Anesthesia and Organ Protection (Zunyi Medical University), Ministry of EducationZunyi Medical UniversityZunyiChina
- Key Laboratory of Brain ScienceZunyi Medical UniversityZunyiChina
- Guizhou Key Laboratory of Anesthesia and Organ ProtectionZunyi Medical UniversityZunyiChina
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
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Li X, Feng D, Ma S, Li M, Zhao S, Tang M. Ventral hippocampus is more sensitive to fluoxetine-induced changes in extracellular 5-HT concentration, membrane 5-HT transporter level and immobility times. Neuropharmacology 2024; 242:109766. [PMID: 37858884 DOI: 10.1016/j.neuropharm.2023.109766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 09/26/2023] [Accepted: 10/15/2023] [Indexed: 10/21/2023]
Abstract
Hippocampal responses to selective 5-HT reuptake inhibitor (SSRI) have long been studied. However, its sub-regional involvements in mediating SSRI's pharmacological effects have not been fully addressed. The current study sought to investigate neurochemical, neurobiological and neurobehavioral changes in response to direct fluoxetine perfusion into the ventral and dorsal sub-regions of the hippocampus in C57BL/6 mice. Following fluoxetine perfusion, time courses of dialysate 5-HT, 5-HT transporter (5-HTT) protein (total, membrane and cytoplasmic fractions), locomotion, and immobility times in the forced swim test (FST) and tail suspension test (TST) were determined. At baseline, 5-HT uptake efficiency assessed by the no-net-flux microdialysis, and 5-HTT protein were measured as well. Results show that fluoxetine dose-dependently increased dialysate 5-HT, lowered membrane 5-HTT protein and increased cytoplasmic fraction without changing the total level, decreased immobility times in both the FST and TST, with greater responses all detected in the ventral sub-region compared to the dorsal sub-region. Fluoxetine didn't affect locomotor activity, ruling out the possibility that fluoxetine's effects on immobility maybe due to alteration in locomotion. Besides, lower 5-HT uptake efficiency and lower membrane 5-HTT protein level were found in the ventral sub-region at baseline. Together, the sub-regional differences at baseline and in responses to fluoxetine added powerful evidence to support the existence of two distinct 5-HT sub-systems in the hippocampus, with greater changes to fluoxetine detected in the ventral sub-system.
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Affiliation(s)
- Xiang Li
- Department of Pharmacy, The Fourth Affiliated Hospital of China Medical University, Shenyang, 110032, China
| | - Dan Feng
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Shenglu Ma
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Mingxing Li
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Shulei Zhao
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Man Tang
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China.
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3
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Dincer B, Halici Z, Cadirci E. Investigation of the Role of Stimulation and Blockade of 5-HT 7 Receptors in Ketamine Anesthesia. J Mol Neurosci 2020; 71:1095-1111. [PMID: 33200380 DOI: 10.1007/s12031-020-01732-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/12/2020] [Indexed: 12/17/2022]
Abstract
Although several pieces of evidence have indicated the ability of the serotonin-7 receptor (5-HTR7) to modulate N-methyl-D-aspartate receptor (NMDAR) activation, the possible impact on ketamine anesthesia has not been examined directly. The purpose of the present study is thus to investigate the possible role of the 5-HTR7 in ketamine anesthesia using a 5-HTR7 agonist and/or antagonist. The influence of a 5-HTR7 agonist/antagonist on ketamine anesthesia for behavioral impact was assessed by testing potential anesthetic parameters. Its functional impact was assessed by mRNA expression with real-time PCR and immunostaining in the hippocampus and prefrontal cortex of mice. Two different doses of ketamine-high and low-were administered to induce anesthesia. In the high-dose ketamine-applied group in particular, the administration of both the 5-HTR7 agonist and antagonist intensified the anesthetic effect of ketamine. The reflection of the change in anesthesia parameters to 5-HTR7 expression was observed as an increase in the hippocampus and a decrease in the prefrontal cortex in the anesthetized groups by stimulation of 5-HTR7. It is noteworthy that the results of NMDAR expressions are parallel to the results of the 5-HTR7 expressions of both the hippocampus and the prefrontal cortex. The 5-HTR7 may play a role in ketamine anesthesia. It may act through NMDAR in ketamine anesthesia, depending on the parallelism between both receptors.
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Affiliation(s)
- Busra Dincer
- Department of Pharmacology, Faculty of Pharmacy, Erzincan Binali Yildirim University, Erzincan, 24100, Turkey
| | - Zekai Halici
- Department of Pharmacology, Faculty of Medicine, Ataturk University, Erzurum, 25240, Turkey.,Clinical Research, Development and Design Application and Research Center, Ataturk University, Erzurum, 25240, Turkey
| | - Elif Cadirci
- Department of Pharmacology, Faculty of Medicine, Ataturk University, Erzurum, 25240, Turkey. .,Clinical Research, Development and Design Application and Research Center, Ataturk University, Erzurum, 25240, Turkey.
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Ackels T, Jordan R, Schaefer AT, Fukunaga I. Respiration-Locking of Olfactory Receptor and Projection Neurons in the Mouse Olfactory Bulb and Its Modulation by Brain State. Front Cell Neurosci 2020; 14:220. [PMID: 32765224 PMCID: PMC7378796 DOI: 10.3389/fncel.2020.00220] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 06/22/2020] [Indexed: 01/10/2023] Open
Abstract
For sensory systems of the brain, the dynamics of an animal’s own sampling behavior has a direct consequence on ensuing computations. This is particularly the case for mammalian olfaction, where a rhythmic flow of air over the nasal epithelium entrains activity in olfactory system neurons in a phenomenon known as sniff-locking. Parameters of sniffing can, however, change drastically with brain states. Coupled to the fact that different observation methods have different kinetics, consensus on the sniff-locking properties of neurons is lacking. To address this, we investigated the sniff-related activity of olfactory sensory neurons (OSNs), as well as the principal neurons of the olfactory bulb (OB), using 2-photon calcium imaging and intracellular whole-cell patch-clamp recordings in vivo, both in anesthetized and awake mice. Our results indicate that OSNs and OB output neurons lock robustly to the sniff rhythm, but with a slight temporal shift between behavioral states. We also observed a slight delay between methods. Further, the divergent sniff-locking by tufted cells (TCs) and mitral cells (MCs) in the absence of odor can be used to determine the cell type reliably using a simple linear classifier. Using this classification on datasets where morphological identification is unavailable, we find that MCs use a wider range of temporal shifts to encode odors than previously thought, while TCs have a constrained timing of activation due to an early-onset hyperpolarization. We conclude that the sniff rhythm serves as a fundamental rhythm but its impact on odor encoding depends on cell type, and this difference is accentuated in awake mice.
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Affiliation(s)
- Tobias Ackels
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Rebecca Jordan
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Andreas T Schaefer
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Izumi Fukunaga
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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Li X, Sun X, Sun J, Zu Y, Zhao S, Sun X, Li L, Zhang X, Wang W, Liang Y, Wang W, Liang X, Sun C, Guan X, Tang M. Depressive-like state sensitizes 5-HT 1A and 5-HT 1B auto-receptors in the dorsal raphe nucleus sub-system. Behav Brain Res 2020; 389:112618. [PMID: 32360167 DOI: 10.1016/j.bbr.2020.112618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 12/14/2022]
Abstract
Dorsal raphe (DR) and median raphe (MR) 5-HT neurons are two distinct sub-systems known to be regulated by 5-HT1A and 5-HT1B auto-receptors. Whether the auto-receptors in each sub-system are functionally altered in depressive-like state remains unknown. The present study is aimed to study a specific circuit (DR-ventral hippocampus and MR-dorsal hippocampus) within each sub-system to investigate changes in receptor sensitivity in the pathogenesis of depression. A mouse model of depression was developed through the social defeat paradigm, and was then treated with fluoxetine (FLX). 5-HT1A auto-receptor in the neuronal cell body (DR or MR) and 5-HT1B auto-receptor in the axonal terminal (ventral or dorsal hippocampus) were directly targeted by local perfusion of antagonists (5-HT1A: WAY100635; 5-HT1B: GR127935) through reverse microdialysis. Time courses of dialysate 5-HT measured at the axonal terminal were subsequently determined for each circuit. At baseline, 5-HT1A and 5-HT1B antagonists dose-dependently increased dialysate 5-HT, with sub-circuit specificity. In the depressive-like state, greater increases in dialysate 5-HT were observed only in the DR-ventral hippocampus circuit following local delivery of both antagonists, which were then fully restored following the FLX treatment. In contrast, no changes were observed in the MR-dorsal hippocampus circuit. Our results demonstrate differential changes in sensitivities of 5-HT1A and 5-HT1B auto-receptors in the DR-ventral hippocampus and MR-dorsal hippocampus circuits. 5-HT1A and 5-HT1B auto-receptors in the DR-ventral hippocampus circuit are sensitized in the depressive-like state. Taken together, these results suggest that the DR sub-system maybe the neural substrate mediating depressive phenotypes.
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Affiliation(s)
- Xiang Li
- Department of Pharmacy, The Fourth Affiliated Hospital of China Medical University, Shenyang, 110032, China
| | - Xianan Sun
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Jing Sun
- Department of Outpatient, Rocket Force University of Engineering Clinic Affiliated to 986 Hospital of Air Force, Xi'an, 710043, China
| | - Yi Zu
- Department of Academic Quality Assurance, China Medical University, Shenyang, 110122, China
| | - Shulei Zhao
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, 20993, USA
| | - Xiao Sun
- Department of Internal Medicine, Shenyang Women's and Children's Hospital, Shenyang, 110011, China
| | - Lu Li
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Xinjing Zhang
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Wei Wang
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Yuezhu Liang
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Wenyao Wang
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Xuankai Liang
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Chi Sun
- Department of Academic Quality Assurance, China Medical University, Shenyang, 110122, China
| | - Xue Guan
- Department of Academic Quality Assurance, China Medical University, Shenyang, 110122, China
| | - Man Tang
- Department of Clinical Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122, China.
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6
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Sial OK, Parise EM, Parise LF, Gnecco T, Bolaños-Guzmán CA. Ketamine: The final frontier or another depressing end? Behav Brain Res 2020; 383:112508. [PMID: 32017978 PMCID: PMC7127859 DOI: 10.1016/j.bbr.2020.112508] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/15/2020] [Accepted: 01/23/2020] [Indexed: 12/12/2022]
Abstract
Two decades ago, the observation of a rapid and sustained antidepressant response after ketamine administration provided an exciting new avenue in the search for more effective therapeutics for the treatment of clinical depression. Research elucidating the mechanism(s) underlying ketamine's antidepressant properties has led to the development of several hypotheses, including that of disinhibition of excitatory glutamate neurons via blockade of N-methyl-d-aspartate (NMDA) receptors. Although the prominent understanding has been that ketamine's mode of action is mediated solely via the NMDA receptor, this view has been challenged by reports implicating other glutamate receptors such as AMPA, and other neurotransmitter systems such as serotonin and opioids in the antidepressant response. The recent approval of esketamine (Spravato™) for the treatment of depression has sparked a resurgence of interest for a deeper understanding of the mechanism(s) underlying ketamine's actions and safe therapeutic use. This review aims to present our current knowledge on both NMDA and non-NMDA mechanisms implicated in ketamine's response, and addresses the controversy surrounding the antidepressant role and potency of its stereoisomers and metabolites. There is much that remains to be known about our understanding of ketamine's antidepressant properties; and although the arrival of esketamine has been received with great enthusiasm, it is now more important than ever that its mechanisms of action be fully delineated, and both the short- and long-term neurobiological/functional consequences of its treatment be thoroughly characterized.
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MESH Headings
- Antidepressive Agents/pharmacology
- Antidepressive Agents/therapeutic use
- Depressive Disorder, Major/drug therapy
- Depressive Disorder, Treatment-Resistant/drug therapy
- Dopamine Plasma Membrane Transport Proteins/drug effects
- Excitatory Amino Acid Antagonists/pharmacology
- Excitatory Amino Acid Antagonists/therapeutic use
- Humans
- Ketamine/pharmacology
- Ketamine/therapeutic use
- Norepinephrine Plasma Membrane Transport Proteins/drug effects
- Receptor, Muscarinic M1/drug effects
- Receptors, AMPA/drug effects
- Receptors, Dopamine D2/drug effects
- Receptors, N-Methyl-D-Aspartate/drug effects
- Receptors, Opioid, delta/drug effects
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, mu/drug effects
- Receptors, Serotonin, 5-HT3/drug effects
- Receptors, sigma/drug effects
- Serotonin Plasma Membrane Transport Proteins/drug effects
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Affiliation(s)
- Omar K Sial
- Texas A&M University: Department of Psychological and Brain Sciences, 4325 TAMU, College Station, TX, 77843, USA
| | - Eric M Parise
- Fishberg Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY, 10029, USA
| | - Lyonna F Parise
- Fishberg Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY, 10029, USA
| | - Tamara Gnecco
- Texas A&M University: Department of Psychological and Brain Sciences, 4325 TAMU, College Station, TX, 77843, USA
| | - Carlos A Bolaños-Guzmán
- Texas A&M University: Department of Psychological and Brain Sciences, 4325 TAMU, College Station, TX, 77843, USA.
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Gartside SE, Yurttaser AE, Burns AL, Jovanović N, Smith KJ, Amegashiti NS, Olthof BMJ. A role for nitric oxide in serotonin neurons of the midbrain raphe nuclei. Eur J Neurosci 2020; 51:1881-1899. [DOI: 10.1111/ejn.14713] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/03/2020] [Accepted: 02/25/2020] [Indexed: 01/24/2023]
Affiliation(s)
- Sarah E. Gartside
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | | | - Amy L. Burns
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | - Nebojša Jovanović
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | - Katie J. Smith
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | | | - Bas M. J. Olthof
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
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Pham TH, Gardier AM. Fast-acting antidepressant activity of ketamine: highlights on brain serotonin, glutamate, and GABA neurotransmission in preclinical studies. Pharmacol Ther 2019; 199:58-90. [DOI: 10.1016/j.pharmthera.2019.02.017] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/25/2019] [Indexed: 12/13/2022]
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Li Y, Zu Y, Li X, Zhao S, Ou F, Li L, Zhang X, Wang W, He T, Liang Y, Sun X, Tang M. Acute corticosterone treatment elicits antidepressant-like actions on the hippocampal 5-HT and the immobility phenotype. Brain Res 2019; 1714:166-173. [DOI: 10.1016/j.brainres.2019.02.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/09/2019] [Accepted: 02/18/2019] [Indexed: 10/27/2022]
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Llamosas N, Perez-Caballero L, Berrocoso E, Bruzos-Cidon C, Ugedo L, Torrecilla M. Ketamine promotes rapid and transient activation of AMPA receptor-mediated synaptic transmission in the dorsal raphe nucleus. Prog Neuropsychopharmacol Biol Psychiatry 2019; 88:243-252. [PMID: 30075169 DOI: 10.1016/j.pnpbp.2018.07.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/10/2018] [Accepted: 07/29/2018] [Indexed: 01/03/2023]
Abstract
Accumulating evidence indicates that the antidepressant effects of ketamine are, in part, mediated by an increase in the AMPA receptor-mediated neurotransmission in depression related areas, such as the prefrontal cortex (PFC). Therefore, activity in PFC-projecting areas related to major depression, such as the dorsal raphe nucleus (DR), may also be modulated by ketamine. We used whole-cell patch-clamp recordings and western blot experiments to determine whether ketamine promotes acute and maintained alterations in glutamatergic transmission and mTOR pathway in the DR. Bath perfusion of ketamine, but not the NMDA receptor antagonist D-AP5, increased the frequency of AMPA receptor-mediated spontaneous EPSCs (sEPSCs) in DR neurons. However, ketamine did not affect evoked EPSCs or spontaneous inhibitory currents (sIPSCs). Pre-incubation of DR slices with the mTOR inhibitor PP242 decreased the frequency of sEPSCs and prevented the effect of ketamine. The results also show that while no electrophysiological effects were detected 24 h after ketamine administration, phosphorylation levels of mTOR were significantly increased in the DR. Nevertheless, expression levels of synaptic proteins were unaffected at that time. Altogether, the present data demonstrate that ketamine transiently increases spontaneous AMPA receptor-mediated neurotransmission in the DR.
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Affiliation(s)
- Nerea Llamosas
- Department of Pharmacology, School of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - Laura Perez-Caballero
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid Neuropsychopharmacology and Psychobiology Research Group, Psychobiology Area, Department of Psychology, University of Cadiz, 11510, Spain
| | - Esther Berrocoso
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid Neuropsychopharmacology and Psychobiology Research Group, Psychobiology Area, Department of Psychology, University of Cadiz, 11510, Spain
| | - Cristina Bruzos-Cidon
- Department of Pharmacology, School of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - Luisa Ugedo
- Department of Pharmacology, School of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - Maria Torrecilla
- Department of Pharmacology, School of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
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Gretenkord S, Rees A, Whittington MA, Gartside SE, LeBeau FEN. Dorsal vs. ventral differences in fast Up-state-associated oscillations in the medial prefrontal cortex of the urethane-anesthetized rat. J Neurophysiol 2016; 117:1126-1142. [PMID: 28003411 PMCID: PMC5340880 DOI: 10.1152/jn.00762.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/20/2016] [Accepted: 12/21/2016] [Indexed: 01/08/2023] Open
Abstract
We demonstrate, in the urethane-anesthetized rat, that within the medial prefrontal cortex (mPFC) there are clear subregional differences in the fast network oscillations associated with the slow oscillation Up-state. These differences, particularly between the dorsal and ventral subregions of the mPFC, may reflect the different functions and connectivity of these subregions. Cortical slow oscillations (0.1–1 Hz), which may play a role in memory consolidation, are a hallmark of non-rapid eye movement (NREM) sleep and also occur under anesthesia. During slow oscillations the neuronal network generates faster oscillations on the active Up-states and these nested oscillations are particularly prominent in the PFC. In rodents the medial prefrontal cortex (mPFC) consists of several subregions: anterior cingulate cortex (ACC), prelimbic (PrL), infralimbic (IL), and dorsal peduncular cortices (DP). Although each region has a distinct anatomy and function, it is not known whether slow or fast network oscillations differ between subregions in vivo. We have simultaneously recorded slow and fast network oscillations in all four subregions of the rodent mPFC under urethane anesthesia. Slow oscillations were synchronous between the mPFC subregions, and across the hemispheres, with no consistent amplitude difference between subregions. Delta (2–4 Hz) activity showed only small differences between subregions. However, oscillations in the spindle (6–15 Hz)-, beta (20–30 Hz), gamma (30–80 Hz)-, and high-gamma (80–150 Hz)-frequency bands were consistently larger in the dorsal regions (ACC and PrL) compared with ventral regions (IL and DP). In dorsal regions the peak power of spindle, beta, and gamma activity occurred early after onset of the Up-state. In the ventral regions, especially the DP, the oscillatory power in the spindle-, beta-, and gamma-frequency ranges peaked later in the Up-state. These results suggest variations in fast network oscillations within the mPFC that may reflect the different functions and connectivity of these subregions. NEW & NOTEWORTHY We demonstrate, in the urethane-anesthetized rat, that within the medial prefrontal cortex (mPFC) there are clear subregional differences in the fast network oscillations associated with the slow oscillation Up-state. These differences, particularly between the dorsal and ventral subregions of the mPFC, may reflect the different functions and connectivity of these subregions.
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Affiliation(s)
- Sabine Gretenkord
- Institute of Neuroscience, Newcastle University, Medical School, Newcastle-upon-Tyne, United Kingdom.,Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and
| | - Adrian Rees
- Institute of Neuroscience, Newcastle University, Medical School, Newcastle-upon-Tyne, United Kingdom
| | - Miles A Whittington
- York-Hull Medical School, F1-Department of Biology, York University, Heslington, United Kingdom
| | - Sarah E Gartside
- Institute of Neuroscience, Newcastle University, Medical School, Newcastle-upon-Tyne, United Kingdom
| | - Fiona E N LeBeau
- Institute of Neuroscience, Newcastle University, Medical School, Newcastle-upon-Tyne, United Kingdom;
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12
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Potential involvement of serotonergic signaling in ketamine's antidepressant actions: A critical review. Prog Neuropsychopharmacol Biol Psychiatry 2016; 71:27-38. [PMID: 27262695 DOI: 10.1016/j.pnpbp.2016.05.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/24/2016] [Accepted: 05/31/2016] [Indexed: 02/07/2023]
Abstract
A single i.v. infusion of ketamine, classified as an N-methyl-d-aspartate (NMDA) receptor antagonist, may alleviate depressive symptoms within hours of administration in treatment resistant depressed patients, and the antidepressant effect may last for several weeks. These unique therapeutic properties have prompted researchers to explore the mechanisms mediating the antidepressant effects of ketamine, but despite many efforts, no consensus on its antidepressant mechanism of action has been reached. Recent preclinical reports have associated the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT) with the antidepressant-like action of ketamine. Here, we review the current evidence for a serotonergic role in ketamine's antidepressant effects. The pharmacological profile of ketamine may include equipotent activity on several non-NMDA targets, and the current hypotheses for the mechanisms responsible for ketamine's antidepressant activity do not appear to preclude the possibility that non-glutamate neurotransmitters are involved in the antidepressant effects. At multiple levels, the serotonergic and glutamatergic systems interact, and such crosstalk could support the notion that changes in serotonergic neurotransmission may impact ketamine's antidepressant potential. In line with these prospects, ketamine may increase 5-HT levels in the prefrontal cortex of rats, plausibly via hippocampal NMDA receptor inhibition and activation of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. In addition, a number of preclinical studies suggest that the antidepressant-like effects of ketamine may depend on endogenous activation of 5-HT receptors. Recent imaging and behavioral data predominantly support a role for 5-HT1A or 5-HT1B receptors, but the full range of 5-HT receptors has currently not been systematically investigated in this context. Furthermore, the nature of any 5-HT dependent mechanism in ketamine's antidepressant effect is currently not understood, and therefore, more studies are warranted to confirm this hypothesis and explore the specific pathways that might implicate 5-HT.
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13
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Miguelez C, Navailles S, De Deurwaerdère P, Ugedo L. The acute and long-term L-DOPA effects are independent from changes in the activity of dorsal raphe serotonergic neurons in 6-OHDA lesioned rats. Br J Pharmacol 2016; 173:2135-46. [PMID: 26805402 PMCID: PMC4908202 DOI: 10.1111/bph.13447] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 01/15/2016] [Accepted: 01/21/2016] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE L-DOPA is still the most efficacious pharmacological treatment for Parkinson's disease. However, in the majority of patients receiving long-term therapy with L-DOPA, its efficacy is compromised by motor complications, notably L-DOPA-induced dyskinesia. Evidence suggests that the serotonergic system is involved in the therapeutic and the side effects of L-DOPA. Here, we investigate if long-term L-DOPA treatment alters the activity of the dorsal raphe nucleus (DRN) and its responses to serotonergic drugs. EXPERIMENTAL APPROACH We measured the responses of serotonergic neurons to acute and chronic L-DOPA treatment using in vivo electrophysiological single unit-extracellular recordings in the 6-OHDA-lesion rat model of Parkinson's disease. KEY RESULTS The results showed that neither acute nor chronic L-DOPA administration (6 mg·kg(-1) s.c.) altered the properties of serotonergic-like neurons. Furthermore, no correlation was found between the activity of these neurons and the magnitude of L-DOPA-induced dyskinesia. In dyskinetic rats, the inhibitory response induced by the 5-HT1A receptor agonist 8-OH-DPAT (0.0625-16 μg·kg(-1) , i.v.) was preserved. Nonetheless, L-DOPA impaired the ability of the serotonin reuptake inhibitor fluoxetine (0.125-8 mg·kg(-1) , i.v) to inhibit DRN neuron firing rate in dyskinetic animals. CONCLUSIONS AND IMPLICATIONS Although serotonergic neurons are involved in the dopaminergic effects of L-DOPA, we provide evidence that the effect of L-DOPA is not related to changes of the activity of DRN neurons. Rather, L-DOPA might reduce the efficacy of drugs that normally enhance the extracellular levels of serotonin. LINKED ARTICLES This article is part of a themed section on Updating Neuropathology and Neuropharmacology of Monoaminergic Systems. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.13/issuetoc.
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Affiliation(s)
- C Miguelez
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of the Basque Country (UPV/EHU), Leioa, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain
| | - S Navailles
- Université de Bordeaux, Institut des Maladies Neurodégénératives, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, Bordeaux, France
| | - P De Deurwaerdère
- Université de Bordeaux, Institut des Maladies Neurodégénératives, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, Bordeaux, France
| | - L Ugedo
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of the Basque Country (UPV/EHU), Leioa, Spain
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14
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Zhan Q, Buchanan GF, Motelow JE, Andrews J, Vitkovskiy P, Chen WC, Serout F, Gummadavelli A, Kundishora A, Furman M, Li W, Bo X, Richerson GB, Blumenfeld H. Impaired Serotonergic Brainstem Function during and after Seizures. J Neurosci 2016; 36:2711-22. [PMID: 26937010 PMCID: PMC4879214 DOI: 10.1523/jneurosci.4331-15.2016] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/11/2016] [Accepted: 01/23/2016] [Indexed: 12/30/2022] Open
Abstract
Impaired breathing, cardiac function, and arousal during and after seizures are important causes of morbidity and mortality. Previous work suggests that these changes are associated with depressed brainstem function in the ictal and post-ictal periods. Lower brainstem serotonergic systems are postulated to play an important role in cardiorespiratory changes during and after seizures, whereas upper brainstem serotonergic and other systems regulate arousal. However, direct demonstration of seizure-associated neuronal activity changes in brainstem serotonergic regions has been lacking. Here, we performed multiunit and single-unit recordings from medullary raphe and midbrain dorsal raphe nuclei in an established rat seizure model while measuring changes in breathing rate and depth as well as heart rate. Serotonergic neurons were identified by immunohistochemistry. Respiratory rate, tidal volume, and minute ventilation were all significantly decreased during and after seizures in this model. We found that population firing of neurons in the medullary and midbrain raphe on multiunit recordings was significantly decreased during the ictal and post-ictal periods. Single-unit recordings from identified serotonergic neurons in the medullary raphe revealed highly consistently decreased firing during and after seizures. In contrast, firing of midbrain raphe serotonergic neurons was more variable, with a mixture of increases and decreases. The markedly suppressed firing of medullary serotonergic neurons supports their possible role in simultaneously impaired cardiorespiratory function in seizures. Decreased arousal likely arises from depressed population activity of several neuronal pools in the upper brainstem and forebrain. These findings have important implications for preventing morbidity and mortality in people living with epilepsy. SIGNIFICANCE STATEMENT Seizures often cause impaired breathing, cardiac dysfunction, and loss of consciousness. The brainstem and, specifically, brainstem serotonin neurons are thought to play an important role in controlling breathing, cardiac function, and arousal. We used an established rat seizure model to study the overall neuronal activity in the brainstem as well as firing of specific serotonin neurons while measuring cardiorespiratory function. Our results demonstrated overall decreases in brainstem neuronal activity and marked downregulation of lower brainstem serotonin neuronal firing in association with decreased breathing and heart rate during and after seizures. These findings point the way toward new treatments to augment brainstem function and serotonin, aiming to prevent seizure complications and reduce morbidity and mortality in people living with epilepsy.
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Affiliation(s)
- Qiong Zhan
- Departments of Neurology, Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China, Department of Neurology, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | | | | | | | | | | | | | | | | | | | - Wei Li
- Departments of Neurology, Department of Neurosurgery, Jinling Hospital, School of Medicine Nanjing University, Nanjing Jiangsu 210002, China, and
| | - Xiao Bo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - George B Richerson
- Departments of Neurology and Molecular Physiology and Biophysics, and Veterans Affairs Medical Center, Iowa City, Iowa 52246
| | - Hal Blumenfeld
- Departments of Neurology, Neuroscience, and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut 06520,
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15
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Johansen SL, Iceman KE, Iceman CR, Taylor BE, Harris MB. Isoflurane causes concentration-dependent inhibition of medullary raphé 5-HT neurons in situ. Auton Neurosci 2015. [PMID: 26213357 DOI: 10.1016/j.autneu.2015.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Anesthetics have a profound influence on a myriad of autonomic processes. Mechanisms of general anesthesia, and how these mechanisms give rise to the multifaceted state of anesthesia, are largely unknown. The ascending and descending serotonin (5-HT) networks are key modulators of autonomic pathways, and are critically involved in homeostatic reflexes across the motor, somatosensory, limbic and autonomic systems. These 5-HT networks are thought to contribute to anesthetic effects, but how anesthetics affect 5-HT neuron function remains a pertinent question. We hypothesized that the volatile anesthetic isoflurane inhibits action potential discharge of medullary raphé 5-HT neurons. METHODS We conducted extracellular recordings on individual neurons in the medullary raphé region of the unanesthetized in situ perfused brainstem preparation to determine how exposure to isoflurane affects 5-HT neurons. We examined changes in 5-HT neuron baseline firing in response to treatment with either 1, 1.5, or 2% isoflurane. We measured isoflurane concentrations by gas chromatography-mass spectrometry (GC-MS) analysis. RESULTS Exposure to isoflurane inhibited action potential discharge in raphé 5-HT neurons. We document a concentration-dependent inhibition over a range of concentrations approximating isoflurane MAC (minimum alveolar concentration required for surgical anesthesia). Delivered concentrations of isoflurane were confirmed using GC-MS analysis. CONCLUSIONS These findings illustrate that halogenated anesthetics greatly affect 5-HT neuron firing and suggest 5-HT neuron contributions to mechanisms of general anesthesia.
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Affiliation(s)
- S L Johansen
- Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775, USA
| | - K E Iceman
- Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775, USA
| | - C R Iceman
- Department of Chemistry and Biochemistry, University of Alaska, Fairbanks, AK 99775, USA
| | - B E Taylor
- Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775, USA
| | - M B Harris
- Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775, USA.
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El Iskandrani KS, Oosterhof CA, El Mansari M, Blier P. Impact of subanesthetic doses of ketamine on AMPA-mediated responses in rats: An in vivo electrophysiological study on monoaminergic and glutamatergic neurons. J Psychopharmacol 2015; 29:792-801. [PMID: 25759403 PMCID: PMC4469544 DOI: 10.1177/0269881115573809] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The rapid antidepressant action of a subanesthetic dose of ketamine in treatment-resistant patients represents the most striking recent breakthrough in the understanding of the antidepressant response. Evidence demonstrates tight interactions between the glutamatergic and monoaminergic systems. It is thus hypothesized that monoamine systems may play a role in the immediate/rapid effects of ketamine. In vivo electrophysiological recordings were carried in male rats following ketamine administration (10 and 25 mg/kg, i.p.) to first assess its effects on monoaminergic neuron firing. In a second series of experiments, the effects of ketamine administration on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)- and N-methyl-D-aspartate receptor (NMDA)-evoked responses in hippocampus CA3 pyramidal neurons were also investigated using micro-iontophoretic applications. Although acute (~2 hours) ketamine administration did not affect the mean firing activity of dorsal raphe serotonin and ventral tegmental area dopamine neurons, it did increase that of locus coeruleus norepinephrine neurons. In the latter brain region, while ketamine also enhanced bursting activity, it did increase population activity of dopamine neurons in the ventral tegmental area. These effects of ketamine were prevented by the prior administration of the AMPA receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide. An increase in AMPA-evoked response of CA3 pyramidal neurons was also observed 30 minutes following acute ketamine administration. The present findings suggest that acute ketamine administration produces a rapid enhancement of catecholaminergic neurons firing activity through an amplification of AMPA transmission. These effects may play a crucial role in the antidepressant effects of ketamine observed shortly following its infusion in depressed patients.
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Affiliation(s)
| | | | - Mostafa El Mansari
- University of Ottawa Institute of Mental Health Research, Mood Disorders Research, Ottawa, ON, Canada
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17
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In vivo imaging of CREB phosphorylation in awake-mouse brain. Sci Rep 2015; 5:9757. [PMID: 26044058 PMCID: PMC4456726 DOI: 10.1038/srep09757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/17/2015] [Indexed: 12/28/2022] Open
Abstract
The cyclic adenosine monophosphate response element binding protein (CREB) is a phosphorylation-dependent transcription factor that plays important roles in memory consolidation and several neuropsychological disorders. Although analyzing the spatiotemporal pattern of CREB phosphorylation is required for elucidating the mechanism of memory consolidation, imaging of phosphorylation of a particular protein in the brain of live animals is impossible at present. Here, we developed a method for visualizing the CREB phosphorylation in the cerebral cortex of an awake mouse using a split luciferase technique. Using this technique, we demonstrated the correlation between the change in CREB phosphorylation at a particular region in the brain and behavioral consequences induced by the administration of reserpine, a psychotropic agent.
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Raphe AMPA receptors and nicotinic acetylcholine receptors mediate ketamine-induced serotonin release in the rat prefrontal cortex. Int J Neuropsychopharmacol 2014; 17:1321-6. [PMID: 24852262 DOI: 10.1017/s1461145714000649] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Several lines of evidence indicate that ketamine has a rapid antidepressant-like effect in rodents and humans, but underlying mechanisms are unclear. In the present study, we investigated the effect of ketamine on serotonin (5-HT) release in the rat prefrontal cortex by in vivo microdialysis. A subcutaneous administration of ketamine (5 and 25 mg/kg) significantly increased the prefrontal 5-HT level in a dose-dependent manner, which was attenuated by local injection of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) antagonists into the dorsal raphe nucleus (DRN). Direct stimulation of AMPARs in the DRN significantly increased prefrontal 5-HT level, while intra-DRN injection of ketamine (36.5 nmol) had no effect. Furthermore, intra-DRN injection of an α 4 β 2-nicotinic acetylcholine receptor (nAChR) antagonist, dihydro-β-erythroidine (10 nmol), significantly attenuated the subcutaneous ketamine-induced increase in prefrontal 5-HT levels. These results suggest that AMPARs and α 4 β 2-nAChRs in the DRN play a key role in the ketamine-induced 5-HT release in the prefrontal cortex.
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