Cytokine Expression Of Astrocytes Following Transient Ischemia Reperfusion And Influence Of Kangdai Ⅰon Reactive Astrocytes In Vivo Or In Vitro

Astrocytes are the most abundant cells in the central nervous system (CNS), and they contribute to maintenance of homeostasis of the neuronal environment by controlling neurotransmitter levels, maintaining calcium homeostasis and synthesizing and releasing neurotrophic and growth factors, but they become activated during ischemia of the central nervous system. It has been reported that they may secrete different regulatory molecules, neurotrophic factors, neuropeptides, and so on. Although they play important roles in the protection and reccovery of neurons under ischemia, little is known about the mechanism. In order to understand the function that activated astrocytes product neurotrophic and controlling apoptosis cytokine after ischemia and reperfusion, it is necessary to investigate these cytokine. In this study ,first, we examined the time course of GFAP, BDNF, bFGF, Bcl-2 and Bax immunoreactivity level and KangdaiⅠintervention mainly in the hippocampus after transient forebrain ischemia and reperfusion using immunohistochemistry . Transient forebrain ischemia in rats was produced according to the method previously reported; second, we examined the time course of GFAP, BDNF, bFGF immunoreactivity level and Kangdai Ⅰintervention in vitro cultured astrocytes transient oxygen and glucose deprivation and reperfusion using immunohistochemistry and in situ hybridization. The purpose of this study was to illustrate the mechanism of ischemia and reperfusion damage. We also investigated the effects of KangdaiⅠ,composed of some extracts of Chinese herbs, on this changes of astrocytes to supply the experimental bases for clinical application.1. Cytokine expression of astrocytes following transient forebrain ischemia reperfusion and influence of Kangdai Ⅰon reactive astrocytes in vivo 1.1 Animal model of transient forebrain ischemia and reperfusionForebrain ischemai was crested according to the procedure described by zhao shu min. Briefly, each rat was anesthetized with chloral hydrate (350mg/kg i.p.), and subjected to 15 min of forebrain ischemia by clipping the common carotid arteries, and followed by reperfusion, then subjected to ischemia again. Mild hypotension was superimposed by exsanguination to offset the transient initial hypertension induced by carotid artery-occlusion in order to make the outcome more uniform in anesthetized animals. In sham-operated animals, the carotid arteries were exposed, but not occluded and exsanguinated. The temperature was recorded with a rectal thermistor and maintained about 36℃. The control animals did not occluded and exsanguinated. Animal were sacrificed after 1d, 3d, 7d, 10d and 15d under deep analgosedation by decapitation. We observed the time course of changed astrocytes after ischemia. Immunohistochemical staining: ABC method.1.2 GFAP, BDNF and bFGF expression of hippocampal astrocytes following transient forebrain ischemia and influence of KangDaiⅠon reactive astrocytesThe results showed that the intensity and the number of GFAP-staining positive astrocytes changed with different time intervals after reperfusion following ischemia, only a few positive astrocytes on reperfusion 1d, more positive astrocytes on reperfusion 3d, the most number of GFAP-staining positive astrocytes on reperfusion 7d-10d, positive astrocytes remained more on reperfusion 15d. KangDaiⅠadministration weakened the reaction of GFAP compared with those of the model. No expression of GFAP in the control and sham-operated control was recognized in all the time evaluated. The change of GFAP in hippocampal astrocytes after transient forebrain ischemia may be closely related to neuron survival. The intensity and the number of BDNF-staining positive astrocytes slightly changed with different time intervals after reperfusion following ischemia, only more positive astrocytes on reperfusion 7-10d. There are positive astrocytes all the time after ischemia, the bFGF expression is the stronges at 7d and 10d. These results indicate that the GFAP expression in hippocampal astrocytes...