Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.12.248229v1?rss=1 Authors: Jones, N. T., Zahid, Z., Grady, S. M., Sultan, Z. W., Zheng, Z., Banks, M. I., WENTHUR, C. J. Abstract: Psilocybin has shown positive preliminary signals in small-scale clinical trials for psychiatric disorders that exhibit maladaptive stress responses as a major component of their presentation. However, there are relatively few assessments of whether an acute administration of psilocybin exhibits reproducible effects in rodent models useful for the study of stress-associated psychiatric disorders. Here, we measured the responses of male C57BL/6J mice to this compound in a battery of relevant behavioral tests. These tests included the open-field test, forced swim test, sucrose preference test, and novelty suppressed feeding test. Furthermore, these tests were presented in either the absence or presence of chronic corticosterone administration, as a chemically induced model of ongoing stress burden. Our results indicate that the effects of psilocybin within these tests are dependent on the chronic hormonal stress burden of the mice: psilocybin alone promotes anxiolytic and hedonic responses, but promotes anxiogenic and anhedonic responses when pre-treated with chronic corticosterone. This identified interaction between stress hormone burden and psilocybin behavioral effects in mice suggests the possibility of further developing rodent behavioral models that can assess additional context-dependent effects of psychedelic administration that are deemed clinically-relevant, but are otherwise difficult to control for, in human studies. Copy rights belong to original authors. Visit the link for more info