Effects Of Folic Acid On Proliferation And Differentiation Of Neural Stem Cells In The Rats With Brain Infarction

ObjectiveTo investigate the effects of folic acid on proliferation,differentiation and apoptosis of neural stem cells(NSCs) after focal cerebral infarction via MAPK signal pathway in rats,and explore its protective mechanisms.MethodsRats were randomly divided into four groups including sham operation(SO) supplemented by saline for 10 ml/kg bw-d,middle cerebral artery occlusion(MCAO) supplemented by saline for 10 ml/kg bw-d,MCAO+low folic acid(MCAO+LFA) supplemented by folic acid for 4 mg/kg bw-d,and MCAO+high folic acid (MCAO+HFA) supplemented by folic acid for 12 mg/kg bw-d.Under U0126 condition,rats were also divided into four groups which were DMSO control group (DMSO),U0126 group(U0126),MCAO+high folic acid group(MCAO+HFA),and folic acid high U0126 group(U0126+MCAO+HFA).In U0126 and U0126+MCAO+ HFA groups,U0126 solution was injected through vena caudalis at 30 min pre-MCAO,and identical volume of DMSO-attenuating solution without U0126 was given in the DMSO group.The cerebral MCAO model was induced by occlusion of middle cerebral artery after 28 days intragastric folic acid administration except the SO group.Serum folic acid of rats was measured with immune chemiluminescence before and after 28 d folic acid supplementation and 7 d after cerebral infarction.The effects of folic acid on proliferation and differentiation of NSCs were detected by double-labeling immunofluorescence and Western Blot at 3,7 and 14 d after MCAO. The morphological changes of cerebral cortex in each group were observed by light microscope.Besides,the ischemic brain neural cell apoptosis was measured with TUNEL method.ResultsNo significant difference was found among serum folic acid of rats in four groups before folic acid supplementation(P＞0.05).Compared with SO and MCAO group,the concentration of serum folic acid were higher in both MCAO+LFA and MCAO+HFA groups after folic acid supplementation(P＜0.05).Besides,the concentration of serum folic acid of MCAO+HFA group is higher than MCAO+LFA group(P＜0.05).Pathology examination of brain show that neurons in cerebral cortex of MCAO group shrunk.The cell's color was deeper.There were cytoplasm and nucleus pyknosis in MCAO group.Compared with MCAO group,the degree of pyknosis was lighten in MCAO+FA groups.There was significant better recovery in cerebral tissue of MCAO+HFA group.The cell morphology of MCAO+HFA group was similar to that of SO group.Under U0126-free conditions,compared with SO and MCAO groups,the proliferation and differentiation into neurons and astrocytes of NSCs in MCAO+FA groups were more active at 3,7 and 14 days(P＜0.05).Under U0126 condition,the differences between U0126+MCAO+HFA group and MCAO+HFA group were significant(P＜0.05).Compared with MCAO+HFA group, the proliferation and differentiation into astrocytes of NSCs in U0126+MCAO+HFA group were lower.No significant difference was found between U0126 group, U0126+MCAO+HFA group(P＞0.05).Compared with SO group,the rate of neural cell apoptosis in MCAO+FA groups was lower after FA supplementation(P＜0.05).ConclusionSupplementation of folic acid by intragastric administration can significantly increased the serum folic acid concentration.Folic acid intake can meliorate the neural function and pathological changes of cerebral cortex in rats with cerebral infarction.Folic acid can enhance the ability of NSCs proliferation and differentiation to astrocytes in rats with cerebral infarction at the dose of both 4 mg/kg bw·d and 12 mg/kg bw·d.Under U0126 condition,folic acid could not promote the proliferation and differentiation to astrocytes of NSCs in MCAO rats,which suggested folic acid maybe promote proliferation and differentiation to astrocytes of NSCs by MAPK signal pathway.Folic acid can also decrease the rate of neural cell apoptosis in MCAO rats.