Protective effect of curcumin on dopamine neurons of Parkinson's disease by activating autophagy / 中华神经医学杂志

ABSTRACT

Objective To investigate whether curcumin protects dopamine neurons in Parkinson's disease (PD) by activating autophagy and discuss its specific mechanism.Methods In vitro,SH-SY5Y human neuroblastoma cells were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPP+) to induce PD cell models.In vivo,C57BL/6 male mice were performed intraperitoneal injection of 30 mg/kg 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) once daily for 7 d continuously to establish PD models.SH-SY5Y human neuroblastoma cells and C57BL/6 male mice were,respectively,divided into normal control group,model group,curcumin group,curcumin and 3-methyladenine (3-MA) group,and 3-MA group.Curcumin was used as intervention treatment,and 3-MA,an autophagy inhibitor,was used individually or concurrently with curcumin as intervention controls:curcumin (40 μmol/L),curcumin (40 μmol/L)+3-MA (4 mmol/L),and 3-MA (4 mmol/L) were added into the cells of curcumin group,curcumin and 3-MA group,and 3-MA group at the time of MPP+ addition;curcumin (80 mg/kg),curcumin (80 mg/kg)+3-MA (2 mg/kg),and 3-MA (2 mg/kg) were added into the mice of curcumin group,curcumin and 3-MA group,and 3-MA group at the time of MPTP injection once daily.In the normal control group,sterile saline was injected into the abdomen simultaneously (30 rmL/kg).In cell groups,after 48 h of drug treatment,the number of surviving dopamine neurons was detected by tyrosine hydroxylase (TH) immunofluorescence;Western blotting was used to detect protein expressions of α-synuclein (α-Syn),and autophagy related proteins lysosome-associated membrane protein 2A (LAMP2A) and microtubule-associated protein 1 light chain 3 (LC3);transcription factor EB (TFEB) levels in the cytoplasm and nucleus were detected separately by Western blotting;reverse transcription (RT)-PCR was used to detect the α-Syn mRNA expression.In mice groups,14 d after the last injection,mice were sacrificed and sections ofmidbrain nigra were gained for detection of TH level by immunohistochemistry,expressions of α-Syn and LC3 were detected by Western blotting.Results (1) As compared with model group,curcumin group had significantly larger number of surviving dopamine neurons both in vitro and in vivo,significantly decreased α-Syn protein and mRNA expressions in vitro,and significantly decreased α-Syn protein expression in vivo (P＜0.05);curcumin group had statistically increased LAMP2A and LC3-Ⅱ protein expressions in vitro and LC3-Ⅱ protein expression in vivo as compared with model group (P＜0.05).(2) As compared with curcumin group,curcumin and 3-MA group had statistically smaller number of surviving dopamine neurons in vitro and in vivo,and statistically increased α-Syn protein expression in vitro (P＜0.05).(3) In vitro,as compared with model group,curcumin group had significantly increased TFEB protein expression in nucleus (P＜0.05),and curcumin and 3-MA group had statistically increased TFEB protein expression in cytoplasm and statistically decreased TFEB protein expression in nucleus (P＜0.05).Conclusion Curcumin has protective effect on dopamine neurons of PD;one of the main mechanisms is that curcumin can activate the autophagy function and promote the clearance of α-Syn;increasing the TFEB expression,promoting the transfer of TFEB to nucleus to perform the transcription function,and then promoting the synthesis of autolysosome may be the main ways to activate the autophagy function.