Olanzapine, an atypical antipsychotic medication, has been associated with weight gain and metabolic toxicity, especially in long term usage. Carnosic acid (CA), a major constituent of rosemary extract, has been shown to improve metabolic abnormalities. In this experiment, the effect of CA on olanzapine-induced obesity and metabolic toxicity has been evaluated. Female Wistar rats were divided into six groups. (1) control; (2) olanzapine (5 mg/kg/day, IP); (3, 4 and 5) olanzapine (5 mg/kg/day, IP) plus CA (5, 10 and 20 mg/kg/day, gavage) and (6) CA (20 mg/kg/day, gavage). Bodyweight and food intake were measured during the study. After 14 days, mean systolic blood pressure (MSBP), glycemia, serum lipid profile, the serum concentration of leptin, insulin, AMPK, P-AMPK, and P-ACC liver protein levels were evaluated. The mean weight in the group received olanzapine increased by 4.8 g at the end of the study. The average food intake was increased by olanzapine. Olanzapine increased triglyceride, fasting blood glucose (FBG), and leptin levels. It increased MSBP and down-regulated P-AMPK/AMPK ratio and P-ACC protein levels. CA (three doses) decreased body weight gain and reduced average food intake at 10 and 20 mg/kg. CA especially at the highest dose decreased the changes in lipid profile, FBG, leptin level, and MSBP. P-AMPK/AMPK and P-ACC protein levels were increased by carnosic acid. In conclusion, the activation of AMPK by CA can be proposed as a key mechanism against olanzapine-induced metabolic toxicity where the activation of AMPK increases fat consumption and regulates glucose hemostasis in the liver.
Keywords: AMPK; Carnosic acid; Metabolic syndrome; Obesity; Olanzapine; Rosemary.