Effects of exercise training on anxiety in diabetic rats

Diabetes mellitus (DM) is a common health problem, which manifests itself with chronic hyperglycemia and impaired insulin action. The prevalence of anxiety disorders tends to be high in the diabetic population. Exercise has a well-known anxiolytic effect, also demonstrated on rodents, but the effect of exercise on the DM-induced anxiety is still unknown. Female, Wistar albino rats were randomly divided into four groups (n=8) (C; EX; DM; DM+EX). DM was induced by injection (i.p.; 50 mg/kg) of Streptozotocin (STZ). Rats exercised in moderate intensity on the treadmill (15m/min; 5°; 30 min) for 5 weeks. Anxiety-like behavior (ALB) was evaluated by Open field test (OFT) and Elevated Plus Maze (EPM). According to OFT, central time and central entry have increased with in EX but not in DM+EX. There was no difference between C and DM. Central latency time didn't differ among groups. Unsupported rearing increased in both EX and DM+EX. There was no significant decrease in DM. Freezing time was significantly increased in the DM group. Exercise training reduced freezing time both in diabetic and non-diabetic animals. EPM results were similar. Time spent in open arm was increased significantly in exercise groups compared to their sedentary matches, and freezing time data were also parallel to OFT. Our study revealed that diabetes had shown an anxiogenic effect, which was not severe, and it only manifested itself on some behavioral parameters. Exercise training was reduced anxiety-like behavior both in diabetic and non-diabetic rats. However, because of the nature of exercise studies, it is hard to separate the anxiolytic effect of exercise from the alteration of locomotion.