Effect Of Endogenous N-3PUFAs On Glial Cell Activity In Mice With Parkinson's Disease

OBJECTIVE: Fat-1 transgenic mice were used as model to investigate the effects of endogenous n-3PUFAs(n-3 polyunsaturated fatty acids)on the activation of microglia and astrocytes,and furtherly explore the pathogenesis of Parkinson's disease in the model mice.METHODS: DNA of 4 week old mice were extracted from the mice born in the same period for PCR.After being identified by gel electrophoresis,they were divided into two groups: WT(wild-type)mice and fat-1 transgenic mice with 18 males each.After four weeks of feeding,a mouse model of Parkinson was established through intraperitoneal injectio MPTP(1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine).The two groups of Parkinson's model mice were concurrently tested by Rotary Rod Fatigue Tester.The difference of the time spent on Rotary Rod Fatigue Tester between the two groups was compared,then a comparison of the time spent on Rotary Rod Fatigue Tester was also made between WT Parkinson's model mice and normal mice of the same age under the same feeding conditions.The cervical dislocation was used to kill the two groups,and their brains were taken for reserve.Six mice brains in each group were randomly selected for corresponding treatment.The changes in the number of synaptic vesicles and synaptic structure in the striatum of the mice brains in the two groups were observed by electron microscopy,compared with normal mice of the same age under the same feeding conditions.6 mice brains in each group were randomly selected for frozen section,immunofluorescence and immunohistochemistry were used.The immunofluorescence of intermediate filament protein GFAP in astrocytes of striatum and protein IBA1 of activated microglia in hippocampusin of the frozen section were compared between the two groups,then TMEM119 immunohistochemistry of the frozen section of the mice brains in two groups were compared.Proteins in the hippocampus,striatum and substantia nigra,total RNA in the hippocampus and striatum were extracted.Western blot experiments of GFAP and IBA1,ELISA experiments of TMEM119 and TH,were conducted with the extracted proteins.The differences of protein contents between the two groups of Parkinson's model mice were compared.The total RNA extracted from each group was used to obtain m RNA of GFAP,IBA1 and TMEM119 by reverse transcription.Real-time Quantitative PCR Detecting System(q PCR)was carried out and the expression of m RNA in two groups of Parkinson's model mice were compared.RESULTS: Compared with WT mice,the residence time of fat-1 transgenic mice on rod fatigue tester was greatly prolonged(about 18%).The number of the synaptic vesicles of fat-1 transgenic mice was increased.The ELISA results of TH showed that the tyrosine hydroxylase level of fat-1 transgenic mice was well above that of WT mice(P<0.0001).The expression of marker protein GFAP in astrocyte,marker protein IBA1,TMEM119 in microglia,the morphology of astrocyte and microglia were observed by the immunofluorescence and immunohistochemistry in the two groups of mice.Western blot of marker protein PGFA in astrocyte and marker protein IBA1 in microglia,ELISA of marker protein TMEM119 in microglia showed that the content of these three proteins in fat-1 transgenic mice was lower than that in WT mice(P<0.05,P<0.05,P<0.0001).The expression of marker protein GFA in astrocyte P,marker protein IBA1,TMEM119 in microglia of fat-1 transgenic mice was obviously lower(P<0.05,P<0.001,P<0.0001).CONCLUSION: The increased n-3 PUFAs in fat-1 transgenic mice are improve a part of the symptoms of MPTP-induced Parkinson's disease in mice,inhibit the activation of microglial cell in the hippocampus and astrocyte in striatum,reduce the oxidative damage to dopaminergic neurons and protect dopaminergic neurons.We speculate that may be one of the reasons why n-3 PUFAs can improve the symptoms of Parkinson's disease.