Effects of Treadmill Exercise on Cognitive Function and Expression of MAP kinase and MKP-1 in Hippocampus of Streptozotocin-induced Diabetic Rats

Abstract

The purposes of this study were to examine the effects of exercise on cognitive function and the expression and correlation of MAP kinases (Mitogen-activated protein kinase; ERK1/2, JNK, p38) and MKP-1 (MAP kinase phosphatases-1) in the hippocampus of diabetic rats. streptozotocin-induced diabetic rats were divided into the control group (CG: n=10), the diabetic group (DG: n=10) and the diabetic with exercise group (DEG: n=10). The rats in DEG was made to treadmill exercise (5 days/week, 30min/day) for 6 weeks. It was showed that the results were a non-significant difference between the groups in the water maze task conducted to evaluate cognitive function, while the CG managed to reach the platform in a short period of time considering the distance travelled, while the DG took relatively more time than the CG. Although the DEG also took more time in comparison with the CG, it managed to reach the platform in a relatively shorter period of time in comparison to the DG. Expression of MAP kinase in the hippocampal tissues was significantly improved in the CG and the DEG, and the expression of MKP-1 that turns on/off the excessive expression of MAP kinase was also found to be significantly increased in the CG and the DEG in comparison to the DG (p<.05). In addition, according to the results of the analysis of correlation between MAP kinase and MKP-1 by using Pearson’s correlation coefficient, MKP-1 was found to have a highly significant correlation with JNK and p38 among the MAP kinase subfamilies (ERK1/2, JNK, p38) that accelerates cell death (p<.05). It is concluded that the effect of exercise to improve spatial cognitive function by affecting the expression of MAP kinase and MKP-1 involved in the signal transduction system of the hippocampus in diabetic rat.