Mice lacking the serotonin transporter do not respond to the behavioural effects of psilocybin.
James J Gattuso, Carey Wilson, Shanshan Li, Anthony J. Hannan, Thibault Renoir
European Journal of Pharmacology March 15, 2025 DOI: 10.1016/j.ejphar.2025.177304 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Serotonin transporter knockout and wild-type mice |
| Intervention | Psilocybin |
| Dose | 1 mg/kg |
| Duration | Single dose; behaviors assessed immediately after injection; weight measured one day post-injection |
| Topics | Anxiety Depression Psilocybin Serotonin |
| Keywords | Serotonin transporter Psychedelic medicine Serotonin system 5-htt Sert Mental health anxiety Mood disorders Neu |
| Citations | 16 |
| Key findings | Functional integrity of the serotonin transporter is essential for psilocybin's acute behavioral effects, as knockout mice lacked head-twitch and hyperlocomotor responses seen in wild-type mice. |
Abstract
Psilocybin is a serotonergic psychedelic with therapeutic potential for several neuropsychiatric disorders, including depression and anxiety disorders. Serotonin transporter (5-HTT) knockout mice (KO) are a well-validated mouse model of anxiety/depression and are relevant to both chronic treatment with serotonin transporter reuptake inhibitors (SSRIs) and polymorphisms in the serotonin transporter-linked polymorphic region (5-HTTLPR) associated with depression/anxiety and resistance to classic antidepressant treatments. However, there is yet to be a study assessing the effect of psilocybin in 5-HTT KO mice. We investigated the effects of a single dose of psilocybin (1 mg/kg) on locomotor activity and the head-twitch response as well as anxiety- and depressive-like behaviour in KO versus wild-type (WT) mice using the light-dark box and Porsolt swim test respectively. We found that both the psilocybin-induced head-twitch and hyperlocomotor responses observed in WT mice were completely absent in KO animals. In female WT mice only, psilocybin was also able to block the weight loss observed one day after intraperitoneal injection. While psilocybin did not alter anxiety- and depression-like behaviours for both genotypes, we revealed a genotype-specific trend for a main effect of treatment for WT females (p = 0.054) in the Porsolt swim test. Finally, we found that only female KO mice exhibit anhedonia-like behaviour in the saccharin-preference test. Our findings highlight the complexity of psilocybin's effects and suggest that functional integrity of 5-HTT is essential for psilocybin's acute behavioural effects. This could also have implications for pharmacogenetics, including individuals with polymorphisms or mutations in 5-HTT.
Comparable studies
Other preclinical and animal studies on psilocybin for anxiety, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Psychedelics, but Not Ketamine, Produce Persistent Antidepressant-like Effects in a Rodent Experimental System for the Study of Depression Rats | 2020 | Preclinical study | |
| Psilocin and ketamine microdosing: effects of subchronic intermittent microdoses in the elevated plus-maze in male Wistar rats Wistar rats | 2018 | Experimental study | n = 40 |
| Striking long-term beneficial effects of single dose psilocybin and psychedelic mushroom extract in the SAPAP3 rodent model of OCD-like excessive self-grooming SAPAP3 knockout mice | 2024 | Randomized controlled trial | n = 50 |
| Psilocybe cubensis extract potently prevents fear memory recall and freezing behavior in short- but not long-term in a rat model of posttraumatic stress disorder. Male rats | 2024 | Preclinical study | |
| Psilocybin induces acute anxiety and changes in amygdalar phosphopeptides independently from the 5-HT2A receptor Mice | 2024 | Experimental study |