Effects of Treadmill Exercise on Spontaneous Firing Activities of Striatal Neurons in a Rat Model of Parkinson's Disease.

Exercise improves motor deficits in Parkinson's disease (PD) patients but the underlying neuronal mechanism is poorly understood. Since the striatum is critical to motor function, we have investigated the potential effects of exercise on the spiking activity of the striatal neurons in a rat model of Parkinson's disease. Twenty-four hours after injection of 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle, rats in exercise groups were trained to exercise on a treadmill. Twenty-eight days after 6-OHDA lesion, apomorphine induced fewer rotations in the PD rats with exercise than in PD + Ex rats. Anatomical examination indicates that compared with the PD rats, PD + Ex rats had an attenuated loss of dopamine axonal fibers in the striatum and dopamine neurons in the substantia nigra pars. Equally important, the abnormal burst firing and firing rates in striatal neurons were lower in the PD + Ex rats than in the PD rats. Taken together, our results suggest that exercise has neuroprotective effects that can reduce the degeneration of the nigrostriatal dopamine system and minimize the abnormal neuronal spike firing in parkinsonian striatum, potentially contributing to exercise's motor-improving effects in PD.