RESUMEN
ObjectiveTo explore the mechanism of Dendrobium huoshanense polysaccharide （DHP） against inflammatory damage of neurons in Parkinson's disease （PD） model. MethodSH-SY5Y cells were randomized into blank group， model group， and DHP group. The survival rate of cells was measured by thiazole blue（MTT） assay， and the levels of lactate dehydrogenase （LDH）， reactive oxygen species （ROS）， malondialdehyde （MDA）， and superoxide dismutase （SOD） were measured by colorimetric analysis. BV-2 microglia were classified into blank group， model group， DHP group， and MCC950 group （positive control group）， and enzyme-linked immunosorbent assay （ELISA） was applied to detect the levels of tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， and interleukin-18 （IL-18）. The expression of NOD-like receptor protein 3 （NLRP3）， adaptor protein apoptosis-associated dot protein （ASC）， cysteine aspartic protease-1 （Caspase-1）， and IL-1β was measured by Western blot. A total of 50 C57BL/6 mice were randomized into blank group， model group， DHP low-dose （100 mg·kg-1） group， DHP equivalent-dose （350 mg·kg-1） group， and MCC950 group （positive control group）， 10 mice in each group. The motor balance and coordination of C57BL/6 mice were observed by beam walking test， tail suspension test and rotarod test. The levels of Iba-1 and tyrosine hydroxylase （TH） were detected by immunofluorescence staining. The damage of dopaminergic neurons in the substantia nigra was detected by FJB staining. The levels of inflammatory factors such as IL-1β， IL-18， and TNF-α in mouse midbrain tissues were detected by ELISA and the protein levels of NLRP3， ASC， Caspase-1， and IL-1β protein were measured by Western blot. ResultCompared with the blank group， the SH-SY5Y model group showed decreased cell survival， increased levels of LDH， ROS， and MDA （P<0.05）， and decreased levels of SOD （P<0.05）. Compared with the model group， the DHP group demonstrated increased cell survival， decreased levels of LDH， ROS， and MDA （P<0.01）， and increased level of SOD （P<0.01）. Compared with the blank group， BV-2 model group had high levels of IL-1β， IL-18， and TNF-α （P<0.05） and high protein expression of NLRP3， Caspase-1， IL-1β， and ASC （P<0.05）. Compared with the model group， DHP and MCC950 groups demonstrated low levels of IL-1β， IL-18， and TNF-α （P<0.01） and low protein expression of NLRP3， Caspase-1， IL-1β， and ASC （P<0.01）. Compared with the blank group， the C57BL/6 model group displayed long time to pass the balance wood （P<0.05）， short time spent on the rod in the rotarod test （P<0.05）， high levels of IL-1β， IL-18， and TNF-α （P<0.05） and expression of Iba-1 in the midbrain substantia nigra （P<0.05）， low TH expression （P<0.05）， more positive neurons in the FJB staining （P<0.05）， and high expression of NLRP3， Caspase-1， ASC， and IL-1β proteins （P < 0.05）. Compared with the model group， the mice in the DHP and MCC950 groups had short time to pass the balance beam （P<0.01）， long time spent on the rod （P<0.01）， low levels of IL-1β， IL-18， and TNF-α （P<0.01）， low Iba-1 expression in midbrain substantia nigra （P<0.01）， high TH expression （P<0.01）， and small number of positive neurons in the midbrain substantia nigra （P<0.01）. The expression of NLRP3， ASC， and IL-1β proteins was lower in the MCC950 group （P<0.01）， and the expression of NLRP3， ASC， Caspase-1 and IL-1β proteins was lower in the DHP equivalent-dose group （P<0.01） than in the model group. ConclusionDHP has anti-oxidative stress effect. It regulates the expression of NLRP3 inflammasome and inhibits the overactivation of microglia， thereby alleviating the neuroinflammatory injury in PD and exerting the neuroprotective effect.