Effects of wheat germ supplementation on hepatic and cardiac mitochondrial function in a model of diet-induced obesity and insulin resistance
Abstract
Obesity is strongly associated with insulin resistance, hyperglycemia, and hyperlipidemia, which are also linked to mitochondrial dysfunction and increased production of reactive oxygen species (ROS). Foods such as wheat germ (WG), which is rich in antioxidants, are thought to protect tissues from damage due to ROS and modulate some negative effects of obesity. This study examined the effects of WG supplementation on body composition, insulin resistance markers, and mitochondrial function in the liver and heart. Six-week-old male C57BL/6 mice were randomized into four dietary treatment groups (n=12 mice/group): control (C, 55% fat kcal), control + 10% WG (C+WG), high fat (HF, 55% fat kcal), or HF+WG. After 90 days of treatment, HF+WG mice had significantly less visceral fat and less insulin resistant compared to the HF group. Addition of WG to the control diet showed no considerable effect. HF feeding compared to control significantly elevated (p<0.05) cardiac oxygen consumption in complex 2, while WG supplementation to the HF diet stabilized this effect to the level of control. Consequently, Sod2 and Pgc1a genes which mediate antioxidant defense and mitochondrial biogenesis respectively, were significantly reduced (p<0.05) in the heart of the HF group compared to control while WG supplementation tended to upregulate both genes. These effects of WG were not observed in the liver. Put together, these results showed that WG supplementation in HF diet reduced insulin resistance and improved the metabolic functions of the cardiac mitochondria.