Second-generation antipsychotic drugs (SGAs) have a high risk for serious metabolic side-effects including dyslipidemia. This study aimed to investigate the acute effects of oral olanzapine treatment on the expression of genes for fatty acid and cholesterol biosynthesis in rats.
Female Sprague–Dawley rats were treated orally with olanzapine (1 mg/kg, equivalent to a human clinical dose of 10 mg) via self-administration aimed to measure pharmacokinetics. Based on the pharmacokinetic analysis, the acute effects of olanzapine on sterol regulatory element binding protein (SREBP)-related fatty acid/cholesterol metabolism genes were investigated in the liver and perirenal white adipose tissue (WAT) by Real-time quantitative PCR.
A pharmacokinetic analysis demonstrated that the maximum concentration of olanzapine in plasma (Cmax) occurred at 6 h with a peak concentration of 276.5 ng/ml after a single oral treatment and with a plasma elimination half-life of 3.5 h after peak. The mRNA expression of SREBP-2 and target genes for cholesterol synthesis and transport was increased 1.9 8.8 fold compared with the control at 6 h after olanzapine administration but returned to basal level at 12 h post-treatment, while the increased mRNA expression of SREBP-1c and its targeted fatty acid-related genes appeared at both 6 h and 12 h post-treatment.
The present study provided evidence that olanzapine at a clinically-relevant dose caused abnormal expression of genes involved in lipid metabolism in the liver and WAT. These results suggest that olanzapine may cause dyslipidemia side-effects through direct effects on lipid biosynthesis and efflux genes associated with SREBP-stimulated transcriptional changes.