Mice lacking melatonin MT2 receptors exhibit attentional deficits, anxiety and enhanced social interaction

Thomson, D. M., Mitchell, E. J., Openshaw, R. L. , Pratt, J. A. and Morris, B. J. (2021) Mice lacking melatonin MT2 receptors exhibit attentional deficits, anxiety and enhanced social interaction. Journal of Psychopharmacology, 35(10), pp. 1265-1276. (doi: 10.1177/02698811211032439) (PMID:34304635) (PMCID:PMC8521347)

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Background: Aside from regulating circadian rhythms, melatonin also affects cognitive processes, such as alertness, and modulates the brain circuitry underlying psychiatric diseases, such as depression, schizophrenia and bipolar disorder, via mechanisms that are not fully clear. In particular, while melatonin MT1 receptors are thought primarily to mediate the circadian effects of the hormone, the contribution of the MT2 receptor to melatonin actions remains enigmatic. Aims: To characterise the contribution of MT2 receptors to melatonin’s effects on cognition and anxiety/sociability. Methods: Mice with a genetic deletion of the MT2 receptor, encoded by the Mtnr1b gene, were compared with wild-type littermates for performance in a translational touchscreen version of the continuous performance task (CPT) to assess attentional processes and then monitored over 3 days in an ethological home-cage surveillance system. Results: Mtnr1b knockout (KO) mice were able to perform at relatively normal levels in the CPT. However, they showed consistent evidence of more liberal/risky responding strategies relative to control mice, with increases in hit rates and false alarm rates, which were maintained even when the cognitive demands of the task were increased. Assessment in the home-cage monitoring system revealed that female Mtnr1b KO mice have increased anxiety levels, whereas male Mtnr1b KO mice show increased sociability. Conclusions: The results confirm that the MT2 receptor plays a role in cognition and also modulates anxiety and social interactions. These data provide new insights into the functions of endogenous melatonin and will inform future drug development strategies focussed on the MT2 receptor.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Openshaw, Rebecca Louise and Thomson, Dr David and Pratt, Dr Judith and Mitchell, Dr Emma and Morris, Professor Brian
Authors: Thomson, D. M., Mitchell, E. J., Openshaw, R. L., Pratt, J. A., and Morris, B. J.
College/School:College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
Journal Name:Journal of Psychopharmacology
Publisher:SAGE Publications
ISSN (Online):1461-7285
Published Online:24 July 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Journal of Psychopharmacology 35(10): 1265-1276
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
173674IMPC: Cognitive and ethological characterisation of mice lacking melatonin MT2 receptorsBrian MorrisMedical Research Council (MRC)MR/P024130/1NP - Centre for Neuroscience