The effect of moderate endurance training on gastrocnemius retinol-binding protein 4 and insulin resistance in streptozotocin-induced diabetic rats

BACKGROUND: Retinol-binding protein 4 (RBP4) is suggested to be involved in the occurrence of insulin resistance. There are contradictory studies about the effects of exercise training on RBP4 levels and insulin resistance. Hence, we designed this study to investigate the impact of moderate endurance training on gastrocnemius RBP4 and insulin resistance in streptozotocin (STZ)-induced diabetic rats. METHOD: Forty male albino Wistar rats were randomly divided into four groups: healthy control (HC), diabetic control (DC), healthy training (HT), and diabetic training (DT). Animals in HT and DT groups ran on a treadmill on the basis of overload principle for 6 weeks, three sessions per week. Rats in DC and DT groups are affected by diabetes using STZ (50 mg/kg of body weight). Gastrocnemius RBP4 content was measured using an enzyme-linked immunosorbent assay kit. Data were analyzed by one-way analysis of variance at P < 0.05 level. RESULTS: Serum blood glucose level (P = 0.001) and insulin resistance (P = 0.001) increased in DC compared with HC group, whereas serum insulin (P = 0.001) and gastrocnemius RBP4 (P = 0.001) reduced. However, there were no significant differences between serum blood glucose level (P = 0.384), insulin resistance (P = 0.999), and RBP4 (P = 0.999) content in DT compared with HT group. CONCLUSION: Moderate endurance training reduces blood glucose level and subsequently improves insulin sensitivity by decreasing gastrocnemius RBP4 content independent of insulin.