Sex-dependent effects of clozapine on PV interneurons, PNNs, and behavior in a neurodevelopmental model with schizophrenia-relevant phenotypes.

Sex modulates both the clinical presentation of schizophrenia (SCZ) and treatment response, yet its impact on the neurobiology of antipsychotic (AP) action remains insufficiently understood. Clozapine (CLZ), the gold standard for treatment-resistant SCZ, shows sex-dependent effects in both clinical and preclinical settings. We recently reported that CLZ treatment is associated with changes in extracellular matrix (ECM) organization and inhibitory circuitry in a neurodevelopmental mouse model with SCZ-relevant phenotypes, but whether these effects differ by sex remained unknown. Here, we investigated sex-dependent effects of CLZ on parvalbumin (PV) interneurons, perineuronal nets (PNNs), ECM-related gene expression, and behavior in adult mice exposed to perinatal ketamine. CLZ restored global PNN density in ketamine-exposed males, whereas in females it selectively increased PV-associated PNNs. At the molecular level, CLZ was associated with shared and sex-dependent changes in the expression of ECM-related genes, including effects on Hapln2, Reelin, and Acan. Behaviorally, CLZ improved cognitive flexibility in both sexes, but rescued social memory only in males, while females showed greater vulnerability to CLZ-induced cognitive impairment in control animals. Together, these findings reveal coordinated sex-dependent changes in PV interneuron- and ECM-related phenotypes, together with distinct behavioral responses following CLZ treatment. These observations support the hypothesis that ECM-related alterations may contribute to sex-dependent variability in CLZ response and reinforce the importance of incorporating sex as a biological variable in preclinical AP research.