Metformin and berberine prevent olanzapine-induced weight gain in rats

Abstract

Olanzapine is a first line medication for the treatment of schizophrenia, but it is also one of the atypical antipsychotics carrying the highest risk of weight gain. Metformin was reported to produce significant attenuation of antipsychotic-induced weight gain in patients, while the study of preventing olanzapine-induced weight gain in an animal model is absent. Berberine, an herbal alkaloid, was shown in our previous studies to prevent fat accumulation in vitro and in vivo. Utilizing a well-replicated rat model of olanzapine-induced weight gain, here we demonstrated that two weeks of metformin or berberine treatment significantly prevented the olanzapine-induced weight gain and white fat accumulation. Neither metformin nor berberine treatment demonstrated a significant inhibition of olanzapine-increased food intake. But interestingly, a significant loss of brown adipose tissue caused by olanzapine treatment was prevented by the addition of metformin or berberine. Our gene expression analysis also demonstrated that the weight gain prevention efficacy of metformin or berberine treatment was associated with changes in the expression of multiple key genes controlling energy expenditure. This study not only demonstrates a significant preventive efficacy of metformin and berberine treatment on olanzapine-induced weight gain in rats, but also suggests a potential mechanism of action for preventing olanzapine-reduced energy expenditure.

Figure 1. Rat body weight gained during treatment (vehicle, olanzapine, olanzapine + berberine, olanzapine + metformin) (A).

* denotes significant difference between olanzapine and control group at P<0.05; # denotes significant difference between olanzapine + berberine and olanzapine group at P<0.05; † denotes significant difference between olanzapine + metformin and olanzapine group at P<0.05. (B) Average food intake (g/rat/day) for each treatment group. (C) Rat white fat, brown fat, and liver weight percentage normalized to body weight in eacg treatment group. * denotes significant difference at P<0.05.

Figure 2. UCP-1 and β-actin protein expression in each treatment group (vehicle, olanzapine, olanzapine + berberine, olanzapine + metformin) (A).

Quantification of relative protein expression of UCP-1 to β-actin, when normalized with the control group (B). * denotes significant difference at P<0.05.