Effect Of MiR-133b On Axonal Degeneration Of Dopaminergic Neuronal Model In Parkinson's Disease

Aim: To evaluate the effect of mi R-133 b on the number of DAG neurons、axons length and expression of tyrosine tydroxylase(TH) 、Rho A in primary cell model of 1-methyl-4-phenyl-pyridinium(MPP+) induced Parkinson’s disease t.Methods: To establish a cell model of of Parkinson’s disease, embryonic rat mesencephalic primary neurons were cultured in vitro and damaged using by MPP+. Primary neurons is divided into divided into four groups: a blank control group, untreated cells; a negative control group,neurons were transfected with lentivirus containing negative control mi RNA(mi R-NC) for 48h; a mi R-NC+MPP+ group, neurons were injured by MPP+ for 24 h and pretreated with mi R-NC for 48 h; a mi R-133 b +MPP+ group, neurons were transfected with lentivirus containing mi R-133 b for 48 h before injured by MPP+ for another 24 h. then we detect expression level of mi R- 133 b By fluorescence quantitative PCR. We us application of immunofluorescence staining to observ DAG neurons morphologyation, and detect DAG neurons quantity and axon length. The protein levels of RHOA was measured by Western blot.Results: MPP+ treatment result in swelling、axonotmesis and beaded change of neurites, accompany with neurite length shortening and a depletion in neurite numbers of each neuron. Compared with blank control group, the number of DAG neurons and axons length decreased significantly, the levels of mi R-133 b were decreased, the level of Rho A protein significant Iy increased, the level of TH protein decreased in mi R-NC+MPP+ group; Compared with mi R-NC+MPP+ group, Over-expression of mi R-133 b by lentivirus transfection,the level of mi R-133 b and the number of DAG neurons and axons length were increased, Rho A relative expression levels decreased obviously,TH relative expression levels increased in mi R-133 b group compared to control mir-NC+MPP+ group.Conclusions: The results suggested that MPP+ treatment decreases expression of mir-133 b and induce axonal degeneration. Overexpression of mir- 133 b can effectively protect dopaminergic neurons and suppress axonal degeneration by target Rho A to inhibit axonal degeneration.