The present study aimed to investigate the effects of maternal dietary butyrate supplementation on energy metabolism and mitochondrial biogenesis in offspring skeletal muscle and the possible mediating mechanisms. Virgin female rats were randomly assigned to either control or butyrate diets (1 % butyrate sodium) throughout gestation and lactation. At the end of lactation (21 d), the offspring were killed by exsanguination from the abdominal aorta under anaesthesia. The results showed that maternal butyrate supplementation throughout gestation and lactation did not affect offspring body weight. However, the protein expressions of G-protein-coupled receptors (GPR) 43 and 41 were significantly enhanced in offspring skeletal muscle of the maternal butyrate-supplemented group. The ATP content, most of mitochondrial DNA-encoded gene expressions, the cytochrome c oxidase subunit 1 and 4 protein contents and the mitochondrial DNA copy number were significantly higher in the butyrate group than in the control group. Meanwhile, the protein expressions of type 1 myosin heavy chain, mitochondrial transcription factor A, PPAR-coactivator-1α (PGC-1α) and uncoupling protein 3 were significantly increased in the gastrocnemius muscle of the treatment group compared with the control group. These results indicate for the first time that maternal butyrate supplementation during the gestation and lactation periods influenced energy metabolism and mitochondrial biogenesis through the GPR and PGC-1α pathways in offspring skeletal muscle at weaning.
Key words: Maternal butyrate: Skeletal muscles: ATP: Mitochondrial biogenesis: RatsDietary fibre is deficient in the diets of modern people. The lack of dietary fibre is viewed as one of the main reason for the current increasing rates of metabolic diseases. Normally, dietary fibre is digested and absorbed in the gastrointestinal tract by complete or partial fermentation to SCFA such as butyric acid (1,2) . Considering the fibre effect on the diet of mothers during gestation and lactation, previous studies indicate that a high-fat, Western-style maternal diet, with additional dietary fibre, has a lower risk for developing CHD, hypertension, diabetes, obesity and other metabolic diseases in the offspring (3,4) . However, the underlying mechanism is still largely unclear.In addition to being the energy source for ruminants and monogastric animals (5,6) , most previous studies suggest that butyrate, a kind of SCFA, might mediate the effects of gut microbiota and nutrition on immunity, metabolism, as well as the pathogenesis of obesity, diabetes mellitus and inflammatory bowel disease (7)(8)(9)(10) . Previous studies have suggested that butyrate supplementation in high-fat diets could improve mitochondrial function by promoting a skeletal muscle type 1 fibre phenotype and physiology (10,11) . A few studies have demonstrated that maternal butyrate supplementation can improve offspring growth and antioxidant capacity (12,13) . However, whether maternal butyrate supplementation has an infl...