Sex dependence of opioid-mediated responses to subanesthetic ketamine
bioRxiv Preprint Server September 6, 2022 Tommaso Di Ianni, Matine M. Azadian, Sedona N. Ewbank et al. 2 citations preprint
Ketamine rapidly reduces depressive symptoms in treatment-resistant depression, but its mechanisms are not fully understood. Recent clinical evidence controversially suggests that ketamine's efficacy may depend on opioid signaling. In rats, blocking opioid receptors suppressed ketamine-induced neurophysiologic changes in brain regions linked to depression and reward, but did not affect changes from a more selective NMDA receptor antagonist. This opioid-dependent response was strongly sex-dependent: absent in females and reversed by removing male gonads. Similar sex-dependent opioid effects appeared in ketamine-evoked structural plasticity and behavioral sensitization. These results indicate that ketamine may induce affective responses via opioid signaling, with subject sex as a strong influence, warranting direct assessment in future clinical trials.