Experimental Studies Of Phenotype Switch Of Arteriolar Smoothmuscle Cell After Ischemia Stroke

【Background and purpose】Vascular smoothmuscle cells(VSMC) have many functions as contraction, synthesis, depot　and secretion. VSMC have significant meaning in Cerebral vascular configuration and activity. The effect of phenotype switching and the change of proliferation/differentiation capability of VSMC in injury are getting more and more attention. α-SM-Actin has been known as the most important sign in phenotype switching of VSMC. Actin can also transfer the signals from both outside and inside of the cell so that it can influence cell motion,growth and differentiation,target recognition and adherence.　Filamin(FLN) can bind to F-actin to transform its three -dimensional configuration ,and as a result, to regulate the contraction of VSMC.But the effect of FLN in phenotype switching and inflammation is not clear. In this study, we are going to observe expression of the two proteins in the arteriolar smoothmuscle cell after ischemia stroke and pathological change by light and electron microscope to find out the meaning of both in phenotype switching, proliferation /differentiation,activity change and inflammatory signal transmission.【Method】Remove brain tissue from fatal case with Cerebral infarct. Rat model of ischemic reperfusion of cerebral middle artery was established. Rats were randomly divided into sham operation group, ischemia/reperfusion group,continuance ischemia group and medicine treated group. The ischemia/reperfusion group are divided into six subgroups according to time diference such as 2h,6h,12h,24h,3d and 7d. MACO2h/R2h group was treated with Batroxobin.　By using immunohistochemical SABC staining method and color image analysis, the expression of α-SM-actin and FLN in cerebral arteriolar smoothmuscle cell were measured. The infarct volume was measured by HE staining and pathological changes were observed with transmission electron microscope.【Results】Compared with control group, the number of positive VSMC of FLN/α-SM-Actin in infarct group remarkly decrease.But PU value of positive VSMC increase in infarct group.The ischemia volume(IV) in medicine treated group is smaller than other groups.The IV in MCAO2h/3d group is the biggest.We can see neuron swelling and necrosis, acidophilia neuron, glial cell proliferation, bleeding and edema surrounding the vessel, PMN infiltration in light microscope. Nucleus Shrinkage, mitochondrion swelling, myelin sheath lysis and endothelial cell swelling can be observed in transmission electronmicroscope.Expression of Actin decreased after 6h reperfusion, and in 24h group the expression is the lowest.In 3d and 7d group expression of Actin increased. Expression of FLN began to decrease after 2h reperfusion, and in 12h group the expression is much lower than other group. In 24h group the expression increased and 3d group is the highest. After 7d repersion, expression of FLN decreased lightly.【Conclusions】1) Ischemia and reperfusion can cause phenotype switch of VSMC; 2) In cerebral arteriosclerosis, healthy VSMC significantly decreased in tunica media but markly increased in endometrium. These VSMC are either Contractil or Synthetic phenotype. The two phenotype cell express higher α-SM-Actin and FLN respectively to maintenance vascular configuration and activity; 3) FLN can be another the most important sign in phenotype switching of VSMC and may be better than α-SM-Actin; 4) The expression result hint the two proteins may relieve Inflammatory reaction and protect cell; 5) Batroxobin can relieve cerebral tissue damage, decrease phenotype switching of VSMC and maintain vascular activity. 6)With koizumi'method,we can get ischemia/reperfusion animal model;...