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Cortical influences of serotonin and glutamate on layer V pyramidal neurons. PROGRESS IN BRAIN RESEARCH 2021; 261:341-378. [PMID: 33785135 DOI: 10.1016/bs.pbr.2020.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Layer V pyramidal neurons constitute principle output neurons of the medial prefrontal cortex (mPFC)/neocortex to subcortical regions including the intralaminar/midline thalamic nuclei, amygdala, basal ganglia, brainstem nuclei and the spinal cord. The effects of 5-hydroxytryptamine (5-HT) on layer V pyramidal cells primarily reflect a range of excitatory influences through 5-HT2A receptors and inhibitory influences through non-5-HT2A receptors, including 5-HT1A receptors. While the 5-HT2A receptor is primarily a postsynaptic receptor on throughout the apical dendritic field of 5-HT2A receptors, activation of a minority of 5-HT2A receptors also appears to increase spontaneous excitatory postsynaptic currents/potentials (EPSCs/EPSPs) via a presynaptic effect on thalamocortical terminals arising from the midline and intralaminar thalamic nuclei. Activation of 5-HT2A receptors by the phenethylamine hallucinogen also appears to increase asynchronous release of glutamate upon the layer V pyramidal dendritic field, an effect that is suppressed by 5-HT itself through non-5-HT2A receptors. Serotonergic hallucinogens acting on 5-HT2A receptors also appears to increase gene expression of immediate early genes (iEG) and other receptors appearing to induce an iEG-like response like BDNF. Psychedelic hallucinogens acting on 5-HT2A receptors also induce head twitches in rodents that appear related to induction of glutamate release. These electrophysiological, biochemical and behavioral effects of serotonergic hallucinogens appear to be related to modulating glutamatergic thalamocortical neurotransmission and/or shifting the balance toward 5-HT2A receptor activation and away from non-5-HT2A receptor activation. These 5-HT2A receptor induced responses are modulated by feedback homeostatic mechanisms through mGlu2, mGlu4, and mGlu8 presynaptic receptors on thalamocortical terminals. These 5-HT2A receptor and glutamatergic interactions also appear to play a role on higher cortical functions of the mPFC such as motoric impulsivity and antidepressant-like behavioral responses on the differential-reinforcement-of low rate 72-s (DRL 72-s schedule). These mutually opposing effects between 5-HT2A receptor and mGlu autoreceptor activation (e.g., blocking 5-HT2A receptors and enhancing activity at mGlu2 receptors) may play a clinical role with respect to currently prescribed or novel antidepressant drugs. Thus, there is an important balance between 5-HT2A receptor activation and activation of mGlu autoreceptors on prefrontal cortical layer V pyramidal cells with respect to the electrophysiological, biochemical and behavioral effects serotonergic hallucinogenic drugs.
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Abstract
Schizophrenia is a major mental illness associated with profound disability. Current treatments for schizophrenia (antipsychotics) all have a similar mechanism of action and are primarily dopamine type 2 receptor (D2R) antagonists. Antipsychotics are not fully effective for the majority of schizophrenia patients, suggesting the need for alternative approaches. The primary focus of this review is to assess the evidence for the role of the serotonin type 2A receptor (5-HT2AR) in schizophrenia. Topics include an overview of 5-HT2AR physiology and pathophysiology in schizophrenia, 5-HT2AR interaction with other neurotransmitter systems, including the glutamatergic system, a review of the 5-HT2AR/d-lysergic acid diethylamide (LSD) model of schizophrenia, a contrast of the 5-HT2AR and glutamatergic models of schizophrenia, and finally, a review of Food and Drug Administration (FDA)-approved and investigational 5-HT2AR-modulating compounds. Recent studies with lumeteperone, pimavanserin, and roluperidone are highlighted.
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Differences in 5-HT2A and mGlu2 Receptor Expression Levels and Repressive Epigenetic Modifications at the 5-HT2A Promoter Region in the Roman Low- (RLA-I) and High- (RHA-I) Avoidance Rat Strains. Mol Neurobiol 2017; 55:1998-2012. [PMID: 28265857 DOI: 10.1007/s12035-017-0457-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/13/2017] [Indexed: 01/12/2023]
Abstract
The serotonin 2A (5-HT2A) and metabotropic glutamate 2 (mGlu2) receptors regulate each other and are associated with schizophrenia. The Roman high- (RHA-I) and the Roman low- (RLA-I) avoidance rat strains present well-differentiated behavioral profiles, with the RHA-I strain emerging as a putative genetic rat model of schizophrenia-related features. The RHA-I strain shows increased 5-HT2A and decreased mGlu2 receptor binding levels in prefrontal cortex (PFC). Here, we looked for differences in gene expression and transcriptional regulation of these receptors. The striatum (STR) was included in the analysis. 5-HT2A, 5-HT1A, and mGlu2 mRNA and [3H]ketanserin binding levels were measured in brain homogenates. As expected, 5-HT2A binding was significantly increased in PFC in the RHA-I rats, while no difference in binding was observed in STR. Surprisingly, 5-HT2A gene expression was unchanged in PFC but significantly decreased in STR. mGlu2 receptor gene expression was significantly decreased in both PFC and STR. No differences were observed for the 5-HT1A receptor. Chromatin immunoprecipitation assay revealed increased trimethylation of histone 3 at lysine 27 (H3K27me3) at the promoter region of the HTR2A gene in the STR. We further looked at the Akt/GSK3 signaling pathway, a downstream point of convergence of the serotonin and glutamate system, and found increased phosphorylation levels of GSK3β at tyrosine 216 and increased β-catenin levels in the PFC of the RHA-I rats. These results reveal region-specific regulation of the 5-HT2A receptor in the RHA-I rats probably due to absence of mGlu2 receptor that may result in differential regulation of downstream pathways.
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Zaki MM, Abdel-Al H, Al-Sawi M. Assessment of plasma amino acid profile in autism using cation-exchange chromatography with postcolumn derivatization by ninhydrin. Turk J Med Sci 2017; 47:260-267. [PMID: 28263499 DOI: 10.3906/sag-1506-105] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 05/28/2016] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND/AIM Autism is a heterogeneous neurodevelopmental disorder. This study aimed to assess the clinical significance of amino acid profile assay in autism using cation-exchange chromatography with ninhydrin postcolumn derivatization. MATERIALS AND METHODS This study included 42 autistic children and 26 apparently healthy children. All participants were subjected to the assay of plasma amino acids (essential, nonessential, and nonstandard) using cation-exchange chromatography with postcolumn derivatization by ninhydrin. RESULTS The levels of most of the essential amino acids were significantly lower in autistic children than controls. As regards nonessential amino acids, significantly lower levels for plasma cysteine, tyrosine, and serine and significantly higher levels for plasma glutamic acid were recorded in autistic children than controls. Finally, the autistic group demonstrated significantly lower levels of α-aminoadipic acid, carnosine, and β-alanine and significantly higher levels of hydroxyproline, phosphoserine, β-amino-isobutyric acid, and ammonia as compared to controls. CONCLUSION The study revealed that autistic children exhibit distinct alterations in the plasma levels of some amino acids, which can in turn participate in the disease etiology and can be applied as a diagnostic tool for early detection of autism.
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Affiliation(s)
- Mona Mohamed Zaki
- Department of Clinical Pathology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Hala Abdel-Al
- Department of Clinical Pathology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Mohamed Al-Sawi
- Department of Pediatrics, Faculty of Medicine, Ain Shams University, Cairo, Egypt
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dos Santos RG, Osório FL, Crippa JAS, Riba J, Zuardi AW, Hallak JEC. Antidepressive, anxiolytic, and antiaddictive effects of ayahuasca, psilocybin and lysergic acid diethylamide (LSD): a systematic review of clinical trials published in the last 25 years. Ther Adv Psychopharmacol 2016; 6:193-213. [PMID: 27354908 PMCID: PMC4910400 DOI: 10.1177/2045125316638008] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
To date, pharmacological treatments for mood and anxiety disorders and for drug dependence show limited efficacy, leaving a large number of patients suffering severe and persistent symptoms. Preliminary studies in animals and humans suggest that ayahuasca, psilocybin and lysergic acid diethylamide (LSD) may have antidepressive, anxiolytic, and antiaddictive properties. Thus, we conducted a systematic review of clinical trials published from 1990 until 2015, assessing these therapeutic properties. Electronic searches were performed using the PubMed, LILACS, and SciELO databases. Only clinical trials published in peer-reviewed journals were included. Of these, 151 studies were identified, of which six met the established criteria. Reviewed studies suggest beneficial effects for treatment-resistant depression, anxiety and depression associated with life-threatening diseases, and tobacco and alcohol dependence. All drugs were well tolerated. In conclusion, ayahuasca, psilocybin and LSD may be useful pharmacological tools for the treatment of drug dependence, and anxiety and mood disorders, especially in treatment-resistant patients. These drugs may also be useful pharmacological tools to understand psychiatric disorders and to develop new therapeutic agents. However, all studies reviewed had small sample sizes, and half of them were open-label, proof-of-concept studies. Randomized, double-blind, placebo-controlled studies with more patients are needed to replicate these preliminary findings.
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Affiliation(s)
- Rafael G. dos Santos
- Departamento de Neurociências e Ciências do Comportamento, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Hospital das Clínicas, Terceiro Andar, Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, Brazil
| | - Flávia L. Osório
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
| | - José Alexandre S. Crippa
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
| | - Jordi Riba
- Centre d’Investigació de Medicaments, Servei de Farmacologia Clínica, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Human Experimental Neuropsy-chopharmacology, Institut de Recerca, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Departament de Farmacologia i Terapèutica, Universitat Autònoma de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Barcelona, Spain
| | - Antônio W. Zuardi
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
| | - Jaime E. C. Hallak
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
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