Effect of treadmill exercise on glutamate transporter proteins and acetylcholinesterase activity in the prefrontal cortex of diabetic rats

Diabetes-induced neurological disorders could be attributed to changes in the neurotransmitter systems. To determine the effects of diabetes mellitus and physical activity on the brain's glutamatergic and cholinergic systems, the levels of glutamate transporter proteins and acetylcholinesterase activity were investigated in the prefrontal cortex of diabetic animals with/without treadmill exercise.

Adult Wistar rats (5 rats/group) were used in this study. Diabetes mellitus was induced by intraperitoneal injection of streptozotocin (60 mg/kg). Control animals received 0.1 M citrate buffer as vehicle. After 14 days, animals were randomly divided into non-exercise and exercise groups. In the exercise groups, animals were subjected to 4 weeks of treadmill exercise (5 days per week). Thereafter, animals were sacrificed and prefrontal cortices were isolated to measure protein levels of astrocytic (GLAST and GLT-1) and neuronal (EAAC1) glutamate transporters and acetylcholinesterase (AChE) activity.

Animals in the diabetic group had higher GLAST and lower EAAC1 levels (P<0.001) compared to the control group, whereas the level of GLT-1 remained unchanged. In addition, a significant decrease in AChE activity was observed in the diabetic group compared to the control group (P<0.001). Treadmill exercise decreased GLAST level (P<0.05) and increased EAAC1 level and AChE activity to the normal levels in the diabetic group.

Despite no significant effect on the elevated level of GLAST, treadmill exercise was able to restore decreased EAAC1 protein and acetylcholinesterase activity observed in the prefrontal of diabetic animals to the control levels.