Kir7.1 Potassium Channel in MC4R Neurons Drives Clozapine Weight Gain in Female Mice

The study used a diet delivering therapeutic clozapine levels to female mice, tracking hyperphagia, fat mass, fatty liver, and glucose intolerance over 12 weeks. Electrophysiology and genetic deletion showed clozapine and risperidone, but not ziprasidone, strengthened MC4R-Kir7.1 inhibition; selective Kir7.1 knockout in MC4R cells cut weight gain by more than half while preserving antipsychotic-like effects. Setmelanotide partially reversed intake increases. Olanzapine weight gain persisted after Kir7.1 deletion, indicating distinct pathways.

Clozapine remains first-line for treatment-resistant schizophrenia yet causes 4-10 kg average gain in patients, raising cardiometabolic risk and discontinuation rates. Prior receptor screens missed this ion-channel link because they focused on 5-HT2C and H1 antagonism. The mouse model reproduces night-time hyperphagia and lacks compensatory energy expenditure seen in some human cohorts.

Evidence quality note: This is a preclinical interventional study in engineered mice with cell-specific knockouts; it identifies a necessary mechanism but cannot establish human dosing, long-term safety, or efficacy of Kir7.1 blockade. Next required study is a randomized, placebo-controlled trial of an MC4R agonist or Kir7.1 modulator added to clozapine in patients, measuring body weight and psychiatric scores at 12-24 weeks.