Influence of Exercise-induced Fatigue on LFPs Oscillation Activity of M1-striatum Pathway and DA Signals on Rats

Objective: In this experiment, the phase synchronization oscillation activity of local field potential (LFPs) was observed in the primary motor cortex (M1) and striatum after exercise-induced fatigue of rats. In combination with the changes of DA signal system, the role of corticostriatal pathway electrical signal coding in the central regulation of exercise-induced fatigue and the effect of nigrostriatal DA system on it were investigated. Methods: Wistar rats were used to establish the model of exercise-induced fatigue. The rats were divided into control group (CG) , 7 days fatigue group (7 FG) and 24 hour recovery group (24 RG) . We used in vivo multichannel recording technology to record electrical activity in the M1 and striatum of rats and observed the electrophysiological changes. The coherence of M1 and striatal synchronization oscillations was also analyzed. We also detected the expression of DA receptor and related transporter proteins in the dorsolateral striatum before and after exercise-induced fatigue by immunohistochemistry. Results: 1) Electrophysiological parameters of M1 and striatum show that power spectral density of α and β band was higher in 7 FG than CG rats (P<0.05) ; After 24 hours of recovery, the PSD value decreased significantly compared with the 7 FG (P<0.05) ; And the coherence value and phase index of β oscillation between motor cortical and striatal was both increased in 7 FG (P<0.05) ; The coefficient of coherence and the STWA ratio in the 24 RG were significantly decreased than 7 FG (P<0.05) ; 2) Compared with CG, the expression of D2DR protein in 7 FG was significantly decreased (P<0.05) while the VMAT2 was significantly increased P<0.05) in the dorsolateral striatum; And the D1DR of the 24 RG was significantly lower than that in the 7 FG (P<0.05) . Conclusion: After exercise-induced fatigue, the reduction of D2DR may be one of the reasons for the changes in the thickness of the postsynaptic density. The activity of GABA in the striatum is enhanced, and feedback to the cortex, resulting in the change of the comprehensive information of the cortex, thus affecting the behavior ability of the rat. It is suggested that alterations in electrical signals may be one of the causes of exercise-induced fatigue symptoms. D2DR, as the key receptor of DA signal system, may be a target for exercise-induced fatigue.