脑缺血再灌注对大鼠下丘脑-垂体-肾上腺-胸腺轴的影响

为探讨脑缺血再灌注损伤对大鼠神经-内分泌和免疫功能的影响,本研究采用免疫组织化学和放射免疫等实验技术,从形态、结构和功能三个层次观察了脑缺血再灌注损伤时大鼠下丘脑-垂体-肾上腺-胸腺(HPAT)轴的变化。结果发现:脑缺血后6h、9h组大鼠垂体重量明显减轻;其下丘脑和垂体激素分泌细胞数量减少,体积缩小;脑缺血后血浆CRH、ACTH和CORT浓度呈一致性先短暂升高后持续下降,T细胞增殖能力、T细胞克隆形成率和IL-2活性明显下降,且上述改变缺血9h组重于6h组。当脑缺血恢复再灌注时,缺血3h再灌注组比缺血6h再灌注组恢复快。以上结果表明:①脑缺血再灌注时,HPAT轴先出现一短暂的激活过程,继而很快转入抑制状态;②脑缺血再灌注损伤后大鼠免疫功能受抑制;③缺血后恢复再灌注早,HPAT轴受损轻,恢复快。

Effects of Cerebral Ischemia and Reperfusion Injury on Hypothalamus-Pituitary Adrenal-Thymus Axis in Rats

The effects of cerebral ishemia and reperfusion injury on the hypothalamus-pituitary-adrenal-thymus (HPAT ) axis were observed in rats under morphological, structural and functional aspects by means of immunohistochemistry and radioimmunoassay. Experimental results showed that the body weights of rats reduced remarkablly vvith reduction of the numbers of the hormone-secreting cells in hypothalamus and pitutiary gland and shrunking of cell volume at the 6 hours and 9 hours groups of cerebral ishemia. The concentrations of corticotropin releasing hormone ( CRH ), adrenocorti-cotropic hormone (ACTH ) and corticosterone (CORT ) in plasma showed consistent reduction after a transient elevation during the course of cerebral ishemia. The ability of T cell proliferation, proportion of T cell clone-forming cells and the activities of IL-2 alltogether reduced. These changes vvere more prominent in the 9 hours group of cerebral ishemia than those observed in the 6 hours group; These results indicate that there appeared a transient course of activation in HPAT axis, and it was then followed by a rapid conversion into suppressive state vvith inhibition of immune functions after cerebral ischemia and reperfusion injury. The earlier the reperfusion after recovery of cerabral reperfusionis instituted, the milder the injury of HPAT axis subjected, and the more rapid of the recovery.