Olive cake reduces obesity by decreasing epididymal adipocyte size, inhibiting oxidative stress and pancreatic lipase, in rat fed high fat diet

Abstract

Purpose The purpose of this study is to investigate the effect of olive cake (OC) on oxidant/antioxidant biomarkers, lipase activity and on the histological analysis of epididymal fat, in high-fat diet (HFD)-induced obese rats. Design/methodology/approach Male obese rats were divided into two groups and were fed an HFD supplemented (HFD-OC) or not (HFD) with OC for 28 days. A control group was fed a standard diet for the same experimental period. Findings HFD significantly increased body weight, which was reduced by OC in the HFD-OC compared to HFD (p = 0.038). Lipase activity was higher (52%; p = 0.009) in the HFD group than the control group. Administration of OC to the obese rats decreased significantly this activity (38%; p = 0.025) compared to the HFD group. Serum thiobarbituric acid-reactive substances, lipid hydroperoxide and advanced oxidation protein products levels were significantly increased in the HFD group than the control group (p = 0.032, p = 0.023 and p = 0.017, respectively). These levels were significantly reduced in HFD-OC compared to the HFD group (p = 0.030, p = 0.021 and p = 0.010, respectively). Superoxide dismutase, glutathione peroxidase and catalase activities were decreased (53%; p = 0.04), (61%; p = 0.03) and (32%; p = 0.002), in the HFD group than the control group. OC restored these activities (46%; p = 0.01), (58%; p = 0.003) and (30%; p = 0.0003) in the HFD-OC rats than the HFD rats. Consumption of the HFD resulted in adipocyte hypertrophy. Indeed, epididymal adipocyte size was significantly larger in the HFD group than the control group (p = 0.0001), whereas it was reduced in the HFD-OC compared to the HFD group (p = 0.012). Originality/value OC possesses an anti-obesity effect. This effect might be mediated by lipase inhibition, reduced oxidative stress and increased antioxidant activities. In addition, the reduction of fat accumulation in adipose tissue by OC consumption is reflected by reducing adipocyte size.