Exercise increases striatal Glu reuptake and improves motor dysfunction in 6-OHDA-induced Parkinson's disease rats

The purpose of this study is to clarify that exercise may improve the motor dysfunction of Parkinson's disease (PD) model rats by increasing the reuptake of glutamate (Glu) in the striatum. The neurotoxin 6-hydroxydopamine (6-OHDA) was injected into the medial forebrain bundle (MFB) of the rats' right brain to establish PD model rats with unilateral injury, and the sham operation group was given the same dose of normal saline at the same site as the control group. The reliability of the model was evaluated by apomorphine (APO)-induced rotation test combined with tyrosine hydroxylase (TH) immunohistochemical staining in the substantia nigra and striatum. The exercise group started treadmill training intervention (11 m/min, 30 min/day, 5d/week, and 4 weeks in total) 1 week after the operation. The balance bar test, suspension test, and the tail-lifting handstand test were used to evaluate exercise performance of rats; RT-PCR and western blotting were used to detect protein and mRNA expression of glutamate transporter-1 (GLT-1) and glutamine synthetase (GS) in the striatum; and isotope labeling was used to detect the ability of Glu reuptake in the striatum. (1) Compared with PD group, the number of TH immunoreactive cells in the substantia nigra and the content of TH immunoreactive fibers in the striatum did not change significantly in PD + Ex group. (2) Compared with PD group, the latency and total time of crossing the balance beam were significantly shorter (P < 0.01), the retention time of two forepaws on the metal wire was significantly longer (P < 0.01), the maximum lifting of head and trunk was significantly increased (P < 0.01) in PD + Ex group. (3) Compared with PD group, the ability of Glu reuptake in the striatum was significantly increased (P < 0.05), the expression levels of GLT-1 and GS mRNA in the striatum were significantly increased (P < 0.05), the protein expression of GLT-1 and GS in the striatum was significantly upregulated (P < 0.05) in PD + Ex group. Exercise intervention can significantly improve the motor dysfunction of PD model rats, increase the ability of striatal Glu reuptake significantly, and upregulate the expression levels of GLT-1 and GS protein and GS mRNA significantly. Exercise intervention may increase the protein expression level of GLT-1 and increase the reuptake ability of Glu in the striatum, thereby reducing the excitotoxic effect of excessive Glu on the postsynaptic membrane, and ultimately alleviate the motor dysfunction in PD model rats.