Abstract: Objective: To investigate the effects of sodium butyrate (NaB) on duodenum mitochondrial energy metabolism and calcium ion transport in obesity prone (OP) and obesity resistant (OR) rats. Methods: Seventy male Sprague-Dawley rats were randomly divided into: normal diet (CON), OP, OP supplemented with 4% NaB (OP + 4% NaB), OR and OR supplemented with 4% NaB (OR + 4% NaB) groups. Body mass gain and food intake were measured weekly. At the end of the 20-week feeding period, all rats were sacrificed. Then, duodenum tissue and plasma were collected quickly for determining antioxidant enzyme activities, mitochondrial energy metabolism, calcium absorption and blood calcium homeostasis-related indicators. Also, the expression of genes related to Ca2+ transport and antioxidant function in duodenum tissue were detected by quantitative real-time polymenose chain reaction (qPCR). The expression levels of important antioxidant proteins were analyzed by Western blot. Results: Compared with the OP group, the OP + 4% NaB group showed significantly decreased body mass gain (P < 0.05); and significantly increased total antioxidant capacity (T-AOC) in the duodenum (P < 0.01), decreased malondialdehyde (MDA) content (P < 0.05), up-regulated mRNA expression of the antioxidant related genes Nrf2 and NQO-1 (P < 0.01), down-regulated mRNA expression of GSK-3β (P < 0.05), and up-regulated expression of Nrf2 protein (P < 0.05). In addition, in the OP + 4% NaB group, the mitochondrial energy metabolism indicators acetyl CoA content and NADH/NAD+ ratio were significantly decreased (P < 0.01), and ATP level was significantly increased (P < 0.01); the level of mitochondrial reactive oxygen species (ROS) was significantly decreased (P < 0.01); the activities of Mn-superoxide dismutase (P < 0.01) and glutathion peroxidase (GSH-Px) (P < 0.05) were significantly increased; urinary calcium excretion was significantly decreased (P < 0.05); and calcium storage level was significantly increased (P < 0.05). Compared with the OR group, the OR + 4% NaB group exhibited significantly increased T-AOC and GSH-Px activity in the duodenum (P < 0.01), decreased MDA content (P < 0.05), up-regulated mRNA expression of Nrf2 (P < 0.05), and increased ATP level (P < 0.05), while there was no significant difference in the other mitochondrial energy metabolism-related indexes (P > 0.05). Also, compared with the OR group, the OR + 4% NaB group showed no significant difference in the indicators related to calcium balance, blood calcium homeostasis and calcium ion transport (P > 0.05). Conclusion: NaB intervention can improve the antioxidant capacity of the duodenum in OP and OR rats, reduce ROS production and maintain mitochondrial redox homeostasis. NaB can increase the intestinal calcium storage level and calcium ion transport capacity of OP rats, and the effect was greater for OP phenotype.

Key words: mitochondria, sodium butyrate, antioxidant, oxidative stress, obesity prone