Optogenetic Activation DA Neurons in SNc Modulates Striatum Low-frequency Oscillation in Exercise-induced Fatigue Rats

Objective:To investigate the effect of optogenetic activation of SNc DA neurons on the low frequency oscillations in striatum of exercise-induced fatigue rats. Methods:Male SD rats were randomly divided into 5 groups:saline control group(SCG),optogenetic control group(OCG),exercise-induced fatigue group(FG),saline fatigue group(SFG)and optogenetic fatigue group(OFG). Dual viral solution was injected in unilateral SNc to selectively transfect dopaminergic neurons in OCG and SFG groups. The 473 nm light stimulation was delivered at a frequency of 3 Hz and 20 Hz,while LFP signals were recorded from the dorsolateral striatum. Results:1)The elevation of striatal α and β oscillations was detected by comparing with the power spectral density(PSD)in the fatigue group. The PSD changes were significantly after 7 days exhaustive exercise(1 D vs. 7 D,P<0.05);2)The mCherry/ChR2 expression was successfully obtained only in the viral injected rats. Light stimulation of SNc DA neurons in OCG significantly reduced the striatal PSD in both α and β band(P<0.05);3)The 20 Hz stimulation was more effective in reduction of striatal α and β oscillation than that of 3 Hz in 7 D exhausted rats(P<0.05). Conclusion:The exercise-induced fatigue could alter electrophysiological activity in striatum,which reduced the rat's mobility. The abnormal changes of α and β oscillation could be significantly reduced by optogenetic activation of nigrostriatal DA system. The 20 Hz stimulation had more prominent effect on prolonged fatigue.