Brexpiprazole caused glycolipid metabolic disorder by inhibiting GLP1/GLP1R signaling in rats

Brexpiprazole (Bre) is a new multi-target antipsychotic drug (APD) approved by the US FDA in 2015, and shows good therapeutic potential. But it lacks assessments on the metabolic side effects, which obstructs the treatment of schizophrenia. Glucagon-like peptide 1 (GLP1), an incretin associated with Insulin action and metabolism, is involved in the metabolic syndrome (MS) caused by most APDs. In this study, we examined the adverse effects of Bre on glycolipid metabolism in rats and determined whether GLP1 was involved in Bre-caused MS. In the first part of experiments, rats were orally administered Bre (0.5 mg· kg^-1· d^-1) for 28 days with aripiprazole (1.0 mg· kg^-1· d^-1) or olanzapine (1.0 mg· kg^-1· d^-1) as the controls. Compared to vehicle, Bre administration significantly increased the weight gain, serum lipid (TG, TC, LDL, FFA), and blood glucose levels accompanied by the hormonal (Insulin, glucagon, GLP1) imbalance, and the impaired glucose tolerance and Insulin sensitivity. Moreover, we demonstrated that Bre administration significantly decreased the protein and mRNA levels of GLP1 in pancreas and small intestine by suppressing CaMKIIα, AMPK, and β-catenin; Bre administration also caused islet dysfunction with decreased GLP1R, PI3K, IRβ expression in pancreas, and the interference of IRS1, PI3K, p-AKT, and GLUT4 expression in the liver and skeletal muscle that represented the Insulin resistance. In the second part of experiments, rats were orally administered Bre (0.5 mg· kg^-1· d^-1) for 42 days. We showed that co-administration with the GLP1 receptor (GLP1R) agonist liraglutide (0.125 mg· kg^-1· d^-1, ip) could ameliorate Bre-caused metabolic abnormalities. Our results demonstrate that GLP1/GLP1R signaling is involved in Bre-induced glycolipid metabolic disorders and co-treatment with liraglutide is an effective intervention against those abnormal metabolisms.