Exercise intervention increases spontaneous locomotion but fails to attenuate dopaminergic system loss in a progressive MPTP model in aged mice.

While exercise is commonly recommended for PD patients to improve motor function, little is known about the disease-altering potential of exercise. Although others have demonstrated neuroprotective or neurorestorative effects of exercise in animal models of PD, the majority of these studies utilize young animals. In order to assess the effects of exercise intervention in a more clinically relevant model, we have subjected aged mice to progressive 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioning and daily treadmill exercise, initiated early in the course of the disease. The MPTP model elicited a 55% reduction in striatal TH as measured by immunohistochemistry compared to sedentary controls, and exercise did not attenuate this loss in exercised MPTP animals. Furthermore, striatal TH and DAT loss, as assessed by western blotting, were not significantly impacted by treadmill exercise in MPTP-lesioned mice. We did find an increase in spontaneous locomotion in exercised mice that was not decreased by MPTP lesioning. This finding may be due, in part, to an increase in TH expression in the motor cortex in exercised MPTP mice.