Effect of electroacupuncture on Nrf2/NLRP3/Caspase-1 pathway mediated-pyroptosis in mice with Parkinson's disease.

Abstract

To observe the effect of electroacupuncture (EA) on nuclear transcription factor E2 related factor 2 (Nrf2)/NOD-like receptor family pyrin domain-containing protein 3 (NLRP3)/cysteine aspartic acid specific protease-1 (Caspase-1) pathway in the substantia nigra (SN) of mice with Parkinson's disease (PD), so as to explore the neuroprotective mechanism of EA. Forty C57BL/6 male mice were randomly divided into 4 groups, namely, control, PD model, EA and sham-EA groups, with 10 mice in each group. The PD mouse model was established by gavage of rotenone for 4 weeks. Mice in the EA group were given EA stimulation (1 mA, 2 Hz) at "Fengfu" (GV36), bilateral "Taichong" (LR3) and "Zusanli" (ST36) for 30 min, once daily for 2 consecutive weeks. And mice in the sham-EA group were given acupuncture at the subcutaneous areas of the same acupoints without EA stimulation. The open-field test was used for assessment of mouse behavior. The levels of interleukin-1β (IL-1β) and interleukin-18 (IL-18) in the serum were detected by enzyme-linked immunosorbent assay . The positive expression of tyrosine hydroxylase (TH) in SN was determined by immunohistochemistry. The mRNA expression levels of Nrf2, NLRP3, Caspase-1, gasdermin D(GSDMD), IL-1β, IL-18 and the protein expression levels of Nrf2, NLRP3, Caspase-1 and GSDMD in the SN were detected by quantitative real-time PCR and Western blot, separately. After modeling, compared with the control group, the behavioral score was increased (P<0.01), the total exercise time, the total distance and the average speed were decreased (P<0.01), and the positive expression of TH and the mRNA and protein expression levels of Nrf2 in the SN were decreased (P<0.01), while the contents of IL-1β and IL-18 in serum, the mRNA and protein expression levels of NLRP3, Caspase-1 and GSDMD and the mRNA expression levels of IL-1β and IL-18 in the SN were up-regulated (P<0.01) in the PD model group. Following EA intervention, the behavioral score was decreased(P<0.01), the total exercise time, total distance and average speed were increased (P<0.01), the positive expression of TH and the mRNA and protein expressions of Nrf2 in SN were up-regulated (P<0.01, P<0.05), while the contents of IL-1β and IL-18 in serum, the mRNA and protein expression levels of NLRP3, Caspase-1 and GSDMD as well as the mRNA expression levels of IL-1β and IL-18 in the SN were down-regulated (P<0.01, P<0.05) in the EA group relative to the PD model and sham-EA groups. There were no significant differences in the above indicators between the PD model and sham-EA groups. EA stimulation of GV36, LR3 and ST36 can improve motor deficits, reduce the loss of dopamine neurons in the SN, and inhibit neuroinflammatory responses in mice with PD, which may be related to its effects in regulating the Nrf2/NLRP3/Caspase-1 pathway mediated pyroptosis.