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OBJECTIVE: To study the neuroprotective effects of gallic acid in animal models of Parkinson's disease (PD) and its related molecular mechanisms. METHODS: Thirty-six mice were randomly divided into control group, 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine(MPTP) group and gallic acid group. Mice in MPTP group and gallic acid group were given an intraperitoneal injection of 30 mg•kg-1 MPTP daily for 7 d. The mice in control group were given the same amount of normal saline at the same time. The mice in gallic acid group received oral administration of 200 mg•kg-1 gallic acid daily from the first day, gallic acid was administered continuously for 14 d, and mice in MPTP group and control group received the same amount of normal saline. After 7 d of drug administration, the behavioral function was evaluated by rod climbing test and suspension test. The expression of tyrosine hydroxylase(TH) in the substantia nigra and striatum were detected by immunohistochemistry. The number of apoptotic neurons in the substantia nigra were measured by TUNEL assay. SIRT3 mRNA levels were analyzed by qRT-PCR, and protein expression levels were detected by Western blot. RESULTS: Compared with the control group, the ability of motor coordination weakened, the TH expression levels decreased in the substantia nigra and striatum, the number of apoptotic neurons in the substantia nigra significantly increased, the SIRT3 mRNA and protein levels in the substantia nigra obviously declined, and the SOD2 protein expression also dramatically reduced in the MPTP group, the differences between the groups were all statistically significant (P<0.05). After treatment with gallic acid, the ability of motor coordination enhanced, the TH expression level elevated, the number of apoptotic neurons markedly reduced, SIRT3 mRNA and protein levels increased, and SOD2 protein expression also up-regulated in the gallic acid group. Compared with the MPTP group, the differences were all statistically significant (P<0.05). CONCLUSION: Gallic acid can improve the behavioral dysfunction and inhibit dopaminergic neurons damage in PD mice. The mechanism of action may be related to the up-regulation of SIRT3 gene expression.
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Aim To investigate the role of SIRT3 in the molecular mechanism of melatonin protecting do-paminergic neurons in Parkinson' s disease ( PD). Methods Forty-eight mice were randomly divided into control group, model group and treatment group. The mice in treatment group received intraperitoneal injection of melatonin (10 mg • kg"1) and MPTP (30 mg • kg ~1). The mice in model group only received intraperitoneal injection of MPTP (30 mg • kg~1 ) , and the mice in control group received the same a-mount of normal saline. Melatonin was administered continuously for 14 days. The expressions of TH and lba-1 in substantia nigra were analyzed by immunohis-tochemistry. The levels of oxidative stress ( ROS, MDA, SOD) and inflammatory factors (TNF-a, IL-lp) in the midbrain were measured by ELISA. SIRT3 mRNA level was analyzed by qRT-PCR, and protein expression level was detected by immunocytochemistry assay and Western blot. Results Compared to control group, the TH expression decreased and Iba-1 expression increased in the substantia nigra, the oxidative stress and inflammatory injury in the midbrain were significantly enhanced, the SIRT3 mRNA and protein levels in the substantia nigra obviously declined, the SOD2 protein expression was also dramatically reduced, and the iNOS protein expression was elevated in model group; the differences between the groups were all statistically significant ( P < 0. 05 ). After treatment with melatonin, the TH expression increased, Iba-1 expression decreased, oxidative stress and inflammatory injury markedly decreased, SIRT3 mRNA and protein levels were elevated, SOD2 protein expression was up-regulated, and iNOS protein expression was down-regulated in treatment group. Compared to model group, the differences were all statistically significant ( P < 0.05). Conclusions Melatonin can counteract the damage of dopaminergic neurons by up-regulating the expression of SIRT3 in PD animal model. Its mechanisms of action are related to inhibiting microglia activation, and alleviating oxidative stress and inflammation injury.
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OBJECTIVE This study aimed to optimize polysaccharides extraction from Urena lobata L.and investigate its antioxidant activity.METHODS The mathematical model was established by re-sponse surface method (RSM) based on the results of single factor experiments, using polysaccha-rides extraction rate as response value,and using the ratio of water to material,cellulase concentra-tion,extraction temperature and time as experimental factors,which was used to screen optimum poly-saccharide extraction conditions from Urena lobata L.. Antioxidant activity of polysaccharides was stud-ied by DPPH and ·OH free radical elimination method. RESULTS The optimum conditions obtained by RSM were as follows:the cellulase level was 10.8 g·L-1,extraction time duration was 72 min,the ra-tio of water to feedstock was 7 mL·g-1,extraction temperature was 43℃,the pH value was 5.0.Under the optimal conditions, there was a difference of less than 5％ between predicted extraction rate 13.37％ and experimental extraction rate 13.32％. The polysaccharide yield was most significantly af-fected by cellulase concentration,followed by extraction time,water to material ratio and extraction tem-perature.IC50of DPPH and·OH were 1.082 g·L-1and 3.202 mg·L-1,respectively.Antioxidant activity of sample polysaccharides was weaker than those of vitamin C. CONCLUSION The polysaccharide extraction process from Urena lobata L. by cellulase enzymolysis approach was obtained, which was convenient and feasible,and extracted polysaccharides had good free radical scavenging activity.