Effect of electroacupuncture regulating NLRP3/Caspase-1 pathway on pyroptosis of dopaminergic neurons in rats with Parkinson's disease

Abstract

To observe the effect of electroacupuncture (EA) on the pyrolysis of dopaminergic neurons in rats with Parkinson's disease (PD), so as to explore its underlying molecular mechanism. Male SD rats were randomly divided into the sham operation, model, EA, MCC950 and EA+MCC950 groups, with 12 rats in each group. The PD rat model was established by two-point injection of 6-OHDA. Rats in the MCC950 group were injected with MCC950 at the dose of 10 mg/kg, once a day; for rats of EA group, EA was applied to "Taichong" (LR3) and "Fengfu"(GV16) for 30 min, once a day; rats in the EA+ MCC950 group were given MCC950 injection and EA once a day. All above interventions were performed for 2 weeks. After the intervention, the behavioral changes of rats were observed using rotating induction experiment, rotating rod experiment and open field experiment; the positive expressions of dopaminergic neuronal markers tyrosine hydroxylase (TH) and α-Synuclein (α-Syn) in substantia nigra striatum were detected by immunohistochemistry; the damage of dopaminergic neurons in substantia nigra striatum was observed after HE staining; immunopositive coexpression of brain nucleotide-binding oligomerization domain like receptor protein 3 (NLRP3), Caspase-1 and ionized calcium binding adapter1 (Iba-1) were detected by immunofluorescence double staining; the levels of interleukin (IL)-1β and IL-18 in brain tissues were detected by ELISA; the protein expression levels of NLRP3, Cleaved Caspase-1 and apoptosis-associated speck-like protein containing a CARD (ASC) in the substantia nigra striatum were detected by Western blot. Compared with the sham operation group, the number of rotations of rotating induction experiment, the residence time in the central area of open field experiment, the positive expression of α-Syn, the positive co-expressions of NLRP3/Iba-1 and Caspase-1/Iba-1, the contents of IL-1β and IL-18 in brain tissues, and the protein expression levels of NLRP3, ASC and Cleaved Caspase-1 in substantia nigra striatum were significantly increased (P<0.05), while the drop latency of rotating rod experiment, the rearing times and the total distance of open field experiment, and the positive expression of TH in substantia nigra striatum were significantly decreased (P<0.05) in the model group. Compared with the model group, the above mentioned markers were reversed in EA, MCC950 and EA+MCC950 groups (P<0.05), and the improvement of the EA+MCC950 group was more obvious than those of the MCC950 and EA groups. In the model group, the neurons were disorderly arranged, the number of neurons was reduced, the cytoplasm was swollen, and some of them were vacuolar degeneration; while the degree of neuronal arrangement disorder, cytoplasmic swelling and the vacuolar degeneration were reduced in varying degrees in the MCC950, EA and EA+MCC950 groups. The ameliorative effect of EA on dopaminergic neuron damage in PD rats may be related to its effects in inhibiting NLRP3/Caspase-1 mediated neuronal pyrosis.