Electroacupuncture improves behavioral activities by suppressing neuroinflammation and TLR4/NF-κB signaling in substantia nigra of midbrain in Parkinson's disease rats

Abstract

To observe the effect of electroacupuncture(EA) at "Fengfu" (GV16) and "Taichong"(LR3) on the expression of tyrosine hydroxylase (TH), α-synuclein (α-syn) and microglial-related microglial (MG), Toll-like receptor 4（TLR4）/nuclear factor kappa B （NF-κB） signaling pathway in the substantia nigra (SN) of midbrain in Rotenone-induced Parkinson's disease (PD) rats, so as to explore its mechanisms underlying improvement of PD. SD male rats were randomly divided into normal control, PD model and EA groups (n=12 in each group). The PD model was established by subcutaneous injection of rotenone (1 mg/kg) at the back of neck. EA (2 Hz, 1 mA) was applied to bilateral GV16 and LR3, once daily for 2 weeks. The rats' behavior(hair color, reaction capacity, locomotion and gait state)scores (0-10 points) were given and the autonomic movement state (trajectory of autonomous motion, total distance, average speed and duration of motion in 8 min) was detected by using open field tests. The immunoactivity of TH and α-syn in the SN tissue were determined by using immunohistochemistry staining, and the number of Iba-1-labelled microglia (MG) was detected by using immunofluorescence staining. The expression levels of TLR4 and NF-κB P65 proteins in the SN were detected by Western blot, and the contents of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the SN were determined by using enzyme-linked immunosorbent assay. In comparison with the normal group, the behavioral score, α-syn immunoactivity, number of Iba-1 labelled microglia, expression of TLR4 and NF-κB P65 proteins and the contents of TNF-α and IL-6 in the SN were significantly increased (P<0.01), whereas the total distance, average speed, duration of motion of the autonomic movement in 8 min, and the TH immunoactivity were remarkably decreased in the model group (P<0.01). After EA intervention, compared with the model group, the increase of the behavioral score, α-syn immunoactivity, number of Iba-1-labelled microglia, expression of TLR4 and NF-κB P65 proteins, the contents of TNF-α and IL-6 in the SN, and the decrease of the total distance, average speed, duration of motion of the autonomic movement in 8 min, and the TH immunoactivity were reversed (P<0.05, P<0.01). EA can improve the behavioral manifestations of PD rats, which may be associated with its functions in down-regulating the abnormal accumulation of pathological α-syn, TLR4/NF-κB signaling, inhibiting activities of microglia and in up-regulating the expression of TH in the SN of midbrain.