Comparison of the effect of voluntary exercise in enriched environment and forced exercise on Wnt-5a expression and Amyloid Beta accumulation in hippocampus of rats with type 3 diabetes

Type 3 diabetes or brain diabetes is a term for Alzheimer, which insulin resistance selectively affects brain and causes cognitive loss. Wnt signaling pathways play role in nervous system, reducing symptoms of Alzheimer's disease, insulin synthesis and diabetes. Although positive effect of physical activities in diseases has been reported, the comparison of types of exercises has been less investigated. The aim of this study was to compare the effect of voluntary in an enriched environment and forced exercise on Wnt-5a expression and Aβ in hippocampus of type3 diabetic rats.

25 rats were divided into 5 groups: healthy control, sham, diabetes3, diabetes3+voluntary exercise in rich environment, diabetes3+forced exercise. Type3 diabetes was induced by intraventricular injection of streptozocin and the model was confirmed by behavioral test. The protocol was done during eight weeks. Wnt-5a expression was done by western blot method and Aβ accumulation was done by thioflavin S staining. Data analysis was done by ANOVA and Tukey's post hoc test (P≤0.05).

Two exercise group had a significant increase in expression of Wnt-5a in hippocampus (P≤0.05). In the comparison between exercise groups, the expression of Wnt-5a increased more in rich environment rats. The accumulation of Aβ in exercise groups was significantly reduced (P≤0.05) compared to the type 3 diabetes group, which was greater in the rich environment.

Forced and voluntary exercises by activating Wnt/β-catenin pathway in brain reduced accumulation of Aβ plaques. Rich environment has better effect in reducing the symptoms of patients compared to forced exercise, which may be due to reduced stressors in brain.