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Lahogue C, Billard JM, Freret T, Bouet V. 5-HT6 Receptors Sex-Dependently Modulate Hippocampal Synaptic Activity through GABA Inhibition. Biomolecules 2023; 13:biom13050751. [PMID: 37238621 DOI: 10.3390/biom13050751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/19/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023] Open
Abstract
The subtype 6 of the serotoninergic receptors (5-HT6Rs) is highly expressed in the hippocampus, and evidence indicates the beneficial effects of 5-HT6Rs blockade on short- and long-term memory in rodents. Nevertheless, the underlying functional mechanisms still need to be established. To this end, we performed electrophysiological extracellular recordings to assess the effects of the 5-HT6Rs antagonist SB-271046 on the synaptic activity and functional plasticity at the CA3/CA1 hippocampal connections of male and female mice slices. We found that basal excitatory synaptic transmission and isolated N-methyl-D-aspartate receptors (NMDARs) activation were significantly increased by SB-271046. The NMDARs-related improvement was prevented by the GABAAR antagonist bicuculline in male but not in female mice. Regarding synaptic plasticity, neither paired-pulse facilitation (PPF) nor NMDARs-dependent long-term potentiation (LTP) (induced either by high-frequency or theta-burst stimulation) was affected by the 5-HT6Rs blockade. Taken together, our results indicate a sex-dependent 5-HT6Rs effect on synaptic activity at the CA3/CA1 hippocampal connections through changes in the excitation/inhibition balance.
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Affiliation(s)
- Caroline Lahogue
- Department of Health, UNICAEN, INSERM, COMETE, CYCERON, FHU A2M2P, CHU Caen, Normandie Université, 14000 Caen, France
| | - Jean-Marie Billard
- Department of Health, UNICAEN, INSERM, COMETE, CYCERON, FHU A2M2P, CHU Caen, Normandie Université, 14000 Caen, France
| | - Thomas Freret
- Department of Health, UNICAEN, INSERM, COMETE, CYCERON, FHU A2M2P, CHU Caen, Normandie Université, 14000 Caen, France
| | - Valentine Bouet
- Department of Health, UNICAEN, INSERM, COMETE, CYCERON, FHU A2M2P, CHU Caen, Normandie Université, 14000 Caen, France
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Shortall SE, Brown AM, Newton-Mann E, Dawe-Lane E, Evans C, Fowler M, King MV. Calbindin Deficits May Underlie Dissociable Effects of 5-HT 6 and mGlu 7 Antagonists on Glutamate and Cognition in a Dual-Hit Neurodevelopmental Model for Schizophrenia. Mol Neurobiol 2020; 57:3439-3457. [PMID: 32533466 PMCID: PMC7340678 DOI: 10.1007/s12035-020-01938-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/13/2020] [Indexed: 12/11/2022]
Abstract
Despite several compounds entering clinical trials for the negative and cognitive symptoms of schizophrenia, few have progressed beyond phase III. This is partly attributed to a need for improved preclinical models, to understand disease and enable predictive evaluation of novel therapeutics. To this end, one recent approach incorporates "dual-hit" neurodevelopmental insults like neonatal phencyclidine plus isolation rearing (PCP-Iso). Glutamatergic dysfunction contributes to schizophrenia pathophysiology and may represent a treatment target, so we used enzyme-based microsensors to evaluate basal- and drug-evoked glutamate release in hippocampal slices from rats that received neonatal PCP and/or isolation rearing. 5-HT6 antagonist-evoked glutamate release (thought to be mediated indirectly via GABAergic disinhibition) was reduced in PCP-Iso, as were cognitive effects of a 5-HT6 antagonist in a hippocampal glutamate-dependent novel object discrimination task. Yet mGlu7 antagonist-evoked glutamatergic and cognitive responses were spared. Immunohistochemical analyses suggest these findings (which mirror the apparent lack of clinical response to 5-HT6 antagonists in schizophrenia) are not due to reduced hippocampal 5-HT input in PCP-Iso, but may be explained by reduced calbindin expression. This calcium-binding protein is present in a subset of GABAergic interneurons receiving preferential 5-HT innervation and expressing 5-HT6 receptors. Its loss (in schizophrenia and PCP-Iso) would be expected to reduce interneuron firing and potentially prevent further 5-HT6 antagonist-mediated disinhibition, without impacting on responses of VIP-expressing interneurons to mGlu7 antagonism. This research highlights the importance of improved understanding for selection of appropriate preclinical models, especially where disease neurobiology impacts on cells mediating the effects of potential therapeutics.
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Affiliation(s)
- Sinead E Shortall
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Angus M Brown
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Eliot Newton-Mann
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Erin Dawe-Lane
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Chanelle Evans
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Maxine Fowler
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK
| | - Madeleine V King
- School of Life Sciences, Medical School, Queen's Medical Centre, The University of Nottingham, Nottingham, NG7 2UH, UK.
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Zhu C, Lin R, Liu C, Huang M, Lin F, Zhang G, Zhang Y, Miao J, Lin W, Huang H. The Antagonism of 5-HT6 Receptor Attenuates Current-Induced Spikes and Improves Long-Term Potentiation via the Regulation of M-Currents in a Pilocarpine-Induced Epilepsy Model. Front Pharmacol 2020; 11:475. [PMID: 32425770 PMCID: PMC7212420 DOI: 10.3389/fphar.2020.00475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/26/2020] [Indexed: 12/02/2022] Open
Abstract
Recent studies have documented that reduced M-current promotes epileptogenesis and attenuates synaptic remodeling. Neurite growth is closely related to the level of 5-HT6 receptor (5-HT6R) in the central nervous system. However, little research is available regarding the relation between 5-HT6R and M-current and the role of 5-HT6R in M-current regulation. Herein, we found that the expression of 5-HT6R was notably increased and the expression of KNCQ2/3, the main components of the M channel, was decreased in a time-dependent manner in pilocarpine-induced chronic epileptic hippocampus. Interestingly, antagonism of 5-HT6R by SB271046 upregulated the expression of KCNQ2 but not KCNQ3. SB271046 greatly alleviated excitatory/inhibitory imbalance and improved the impaired LTP in the chronic epileptic hippocampus. Further mechanism exploration revealed that the above effects of SB271046 can be reversed by the M-channel inhibitor XE991, which also confirmed that SB271046 can indeed improve abnormal M current. These data indicate that the antagonism of 5-HT6R may decrease the excitability of hippocampal pyramidal neurons in chronic epileptic rats and improve the impaired long-term potentiation by upregulating the expression of KCNQ2 in the M-channel.
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Affiliation(s)
- Chaofeng Zhu
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Rong Lin
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Changyun Liu
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Mingzhu Huang
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Feng Lin
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Gan Zhang
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Yuying Zhang
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Junjie Miao
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Wanhui Lin
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Huapin Huang
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou, China.,Department of Electrophysiology, Fujian Key Laboratory of Molecular Neurology, Fuzhou, China.,Department of Geriatrics, Fujian Medical University Union Hospital, Fuzhou, China
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