Psilocybin Reduces Grooming in the SAPAP3 Knockout Mouse Model of Compulsive Behaviour

Acute psilocybin administration reduced compulsive grooming behavior in male SAPAP3 knockout mice, a model of obsessive-compulsive disorder, for up to eight days after a single injection. The compound did not affect anxiety-like behaviors. Psilocybin increased locomotion in wild-type mice but not in knockouts, suggesting underlying serotonergic differences. Both genotypes showed the typical head-twitch response, confirming the drug's hallucinogenic effect at the 1 mg/kg dose. The findings indicate psilocybin may have enduring anti-compulsive potential.

Study at a glance

Abstract

Abstract Psilocybin is a serotonergic psychedelic compound which shows promise for treating compulsive behaviours. This is particularly pertinent as compulsive disorders require research into new pharmacological treatment options as the current frontline treatments such as selective serotonin reuptake inhibitors, require chronic administration, have significant side effects, and leave almost half of the clinical population refractory to treatment. In this study, we investigated psilocybin administration in male and female SAPAP3 knockout (KO) mice, a well-validated mouse model of obsessive compulsive and related disorders. We assessed the effects of acute psilocybin (1 mg/kg, intraperitoneal) administration on head twitch and locomotor behaviour as well as anxiety- and compulsive-like behaviours at multiple time-points (1-, 3- and 8-days post-injection). While psilocybin did not have any effect on anxiety-like behaviours, we revealed for the first time that acute psilocybin administration led to enduring reductions in compulsive behaviour in male SAPAP3 KO mice and reduced grooming behaviour in female WT and SAPAP3 KO mice. We also found that psilocybin increased locomotion in wild-type littermates but not in SAPAP3 KO mice, suggesting in vivo serotonergic dysfunctions in KO animals. On the other hand, the typical head-twitch response following acute psilocybin (confirming its hallucinogenic-like effect at this dose) was observed in both genotypes. Our novel findings suggest that acute psilocybin may have potential to reduce compulsive-like behaviours (up to 1 week after a single injection). Our study can inform future research directions as well as supporting the utility of psilocybin as a novel treatment option for compulsive disorders.