Olanzapine inhibits hepatic apolipoprotein A5 secretion inducing hypertriglyceridemia in schizophrenia patients and mice

Olanzapine, an antipsychotic drug, was reported to induce hypertriglyceridemia, whereas the underlying mechanism remains incompletely understood. This study was to determine the role of apolipoprotein A5 (apoA5) in olanzapine-induced hypertriglyceridemia. In this study, 36 drug-naive and first-episode schizophrenic adult patients (aged 18-60 years) in a multi-center clinical trial (ClinicalTrials.gov NCT03451734) were enrolled. Before and after olanzapine treatment, plasma lipid and apoA5 levels were detected. Moreover, 21 female C57BL/6 J mice (8 weeks old) were divided into 3 groups (n = 7/each group): low-dose olanzapine (3 mg/kg/day), high-dose olanzapine (6 mg/kg/day) and control group. After 6 weeks, plasma glucose, lipids and apoA5 as well as hepatic apoA5 protein and mRNA expression in these animals were detected. In our study in vitro, primary mouse hepatocytes and HepG2 cells were treated with olanzapine of 25, 50, 100 mol/L, respectively. After 24 hours, apoA5 protein and mRNA levels in hepatocytes were detected. Our study showed that olanzapine treatment significantly increased plasma triglyceride levels and decreased plasma apoA5 levels in these schizophrenic patients. A significant negative correlation was indicated between plasma triglyceride and apoA5 levels in these patients. Consistently, olanzapine dose-dependently increased plasma triglyceride levels and decreased plasma apoA5 levels in mice. Surprisingly, an elevation of hepatic apoA5 protein levels was detected in mice after olanzapine treatment, with no changes of APOA5 mRNA expression. Likewise, olanzapine increased apoA5 protein levels in hepatocytes in vitro, without changes of hepatocyte APOA5 mRNA. Therefore, our study provides the first evidence about the role of apoA5 in olanzapine-induced hypertriglyceridemia. Furthermore, plasma apoA5 reduction, resulting in hypertriglyceridemia, could be attributed to olanzapine-induced inhibition of hepatic apoA5 secretion.