Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress

Abstract Depression and anxiety are disabling and high incidence mental disorders characterized by phenotypic heterogeneity. Currently available treatments show severe limitations. Thus, there is an urgent need for effective treatments in this population. In the search for novel rapid-acting antidep...

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Main Authors: Ines Erkizia-Santamaría, Igor Horrillo, Nerea Martínez-Álvarez, Daniel Pérez-Martínez, Guadalupe Rivero, Amaia M. Erdozain, J. Javier Meana, Jorge E. Ortega
Format: Article
Language:English
Published: Nature Publishing Group 2025-06-01
Series:Translational Psychiatry
Online Access:https://doi.org/10.1038/s41398-025-03421-4
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author Ines Erkizia-Santamaría
Igor Horrillo
Nerea Martínez-Álvarez
Daniel Pérez-Martínez
Guadalupe Rivero
Amaia M. Erdozain
J. Javier Meana
Jorge E. Ortega
author_facet Ines Erkizia-Santamaría
Igor Horrillo
Nerea Martínez-Álvarez
Daniel Pérez-Martínez
Guadalupe Rivero
Amaia M. Erdozain
J. Javier Meana
Jorge E. Ortega
author_sort Ines Erkizia-Santamaría
collection DOAJ
description Abstract Depression and anxiety are disabling and high incidence mental disorders characterized by phenotypic heterogeneity. Currently available treatments show severe limitations. Thus, there is an urgent need for effective treatments in this population. In the search for novel rapid-acting antidepressants, the psychedelic psilocybin has emerged as a promising therapy in several clinical trials. However, its antidepressant mechanism of action is still not well understood. The aim of the present study was to evaluate the therapeutic potential of psilocybin in ameliorating the adverse behavioural and neurochemical consequences of chronic stress. To this end, a chronic unpredictable mild stress (CUMS) animal model was used, and psilocybin treatment was administered (two doses of 1 mg/kg, i.p., administered 7 days apart). Psilocybin reversed impairments in anhedonia and behavioural despair dimensions of depressive phenotype but not in apathy-related behaviour. Psilocybin administration was also able to exert an anxiolytic-like effect on treated animals. Physiological alterations caused by stress, indicative of a hyperactive hypothalamic-pituitary-adrenal axis (HPA), were not reversed by psilocybin. When neuroplasticity-related proteins were assessed in cerebral cortex, brain-derived neurotrophic factor (BDNF) was found to be decreased in stressed animals, and treatment did not reverse such impairment. Psilocybin administration increased the expression and function of serotonin-2A-receptor (5HT2AR) in brain cortex of control and CUMS groups. Furthermore, psilocybin treatment caused a selective increase in the expression of glucocorticoid-receptor (GR) in brain cortex of CUMS mice. In conclusion, psilocybin was able to rescue impairments in the depressive phenotype, and to induce anxiolytic-like effects. Furthermore, an enhancement in sensitivity to psilocybin-induced HTR was observed following a booster dose. Altogether, this work provides new knowledge on the putative benefit/risk actions of psilocybin and contributes to the understanding of the therapeutic mechanism of action of psychedelics.
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spelling doaj-art-33abdc5d794142d78eee180acfa788ba2025-08-20T03:45:32ZengNature Publishing GroupTranslational Psychiatry2158-31882025-06-0115111310.1038/s41398-025-03421-4Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stressInes Erkizia-Santamaría0Igor Horrillo1Nerea Martínez-Álvarez2Daniel Pérez-Martínez3Guadalupe Rivero4Amaia M. Erdozain5J. Javier Meana6Jorge E. Ortega7Department of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUDepartment of Pharmacology, University of the Basque Country UPV/EHUAbstract Depression and anxiety are disabling and high incidence mental disorders characterized by phenotypic heterogeneity. Currently available treatments show severe limitations. Thus, there is an urgent need for effective treatments in this population. In the search for novel rapid-acting antidepressants, the psychedelic psilocybin has emerged as a promising therapy in several clinical trials. However, its antidepressant mechanism of action is still not well understood. The aim of the present study was to evaluate the therapeutic potential of psilocybin in ameliorating the adverse behavioural and neurochemical consequences of chronic stress. To this end, a chronic unpredictable mild stress (CUMS) animal model was used, and psilocybin treatment was administered (two doses of 1 mg/kg, i.p., administered 7 days apart). Psilocybin reversed impairments in anhedonia and behavioural despair dimensions of depressive phenotype but not in apathy-related behaviour. Psilocybin administration was also able to exert an anxiolytic-like effect on treated animals. Physiological alterations caused by stress, indicative of a hyperactive hypothalamic-pituitary-adrenal axis (HPA), were not reversed by psilocybin. When neuroplasticity-related proteins were assessed in cerebral cortex, brain-derived neurotrophic factor (BDNF) was found to be decreased in stressed animals, and treatment did not reverse such impairment. Psilocybin administration increased the expression and function of serotonin-2A-receptor (5HT2AR) in brain cortex of control and CUMS groups. Furthermore, psilocybin treatment caused a selective increase in the expression of glucocorticoid-receptor (GR) in brain cortex of CUMS mice. In conclusion, psilocybin was able to rescue impairments in the depressive phenotype, and to induce anxiolytic-like effects. Furthermore, an enhancement in sensitivity to psilocybin-induced HTR was observed following a booster dose. Altogether, this work provides new knowledge on the putative benefit/risk actions of psilocybin and contributes to the understanding of the therapeutic mechanism of action of psychedelics.https://doi.org/10.1038/s41398-025-03421-4
spellingShingle Ines Erkizia-Santamaría
Igor Horrillo
Nerea Martínez-Álvarez
Daniel Pérez-Martínez
Guadalupe Rivero
Amaia M. Erdozain
J. Javier Meana
Jorge E. Ortega
Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
Translational Psychiatry
title Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
title_full Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
title_fullStr Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
title_full_unstemmed Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
title_short Evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
title_sort evaluation of behavioural and neurochemical effects of psilocybin in mice subjected to chronic unpredictable mild stress
url https://doi.org/10.1038/s41398-025-03421-4
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