组胺对大鼠脑皮质内血管的作用

目的探讨组胺对大鼠脑片皮质内血管的调控作用和机制。方法免疫组化方法检测H1和H2受体在大鼠脑皮质内血管的表达。采用鉴别干涉对比显微镜观察大鼠脑片额叶皮质血管,实时检测和记录组胺引起的血管内径变化。为观察组胺对脑皮质内血管的收缩作用是否与组胺H1、H2受体有关,用H1受体拮抗剂苯海拉明和H2受体拮抗剂西咪替丁预处理脑片,再观察组胺的作用。结果H1受体和H2受体在脑皮质血管壁呈免疫反应阳性。组胺产生浓度依赖性血管收缩,血管收缩率从(1.48±0.67)%到(32.91±7.91)%。除在高浓度(30、100μmol/L)之间没有显著性差异(P>0.05)外,各浓度间都有显著性差异(P<0.01)。苯海拉明预处理脑片,组胺没有引起血管变化。用西咪替丁预处理脑片,组胺仍引起血管收缩,各浓度组间存在显著性差异(P<0.05)。与单纯加入组胺相比,在10和30μmol/L浓度有显著性差异(P<0.05)。结论组胺可引起脑皮质内血管的收缩,其机制是通过H1受体介导。

Effect of histamine on intracortical blood vessels of rats

OBJECTIVE: To investigate histamine-induced changes of the intracortical vessels in the cortical slice of rat brain. METHODS: Immunohistochemistry was employed to detect the expression of H1 and H2 receptors in the intracortical blood vessels of rats. Histamine-induced constriction of the intracortical blood vessels of the brain slices was observed with differential interference contrast microscope. Measurements of the luminal diameter were made on-line during the course of the experiment and confirmed off-line from the stored images. In order to observe whether histamine H1 and H2 receptors affected histamine-induced constriction, the intracortical blood vessels in the brain slices were pre-treated with H1 receptor antagonist diphenhydramine and H2 receptor antagonist cimetidine. RESULTS: Expression of H1 and H2 receptors was detected in the intracortical blood vessels of the rat brain. Histamine (1-100 micromol/L) induced a concentration-dependent constriction from (1.48-/+0.67)% to (32.91-/+7.91)%. The reactions to each histamine concentration were significantly (P<0.01) different from each other, with the exception of the highest histamine concentrations (30 and 100 micromol/L) when maximal constriction due to histamine were observed (P>0.05). With pre-treatment of the slice with 10 micromol/L diphenhydramine, application of histamine did not elicit constriction. Pre-treatment of the slice with 10 micromol/L cimetidine did not completely inhibit but somehow significantly weakened vascular constriction in response to histamine treatment at 10 and 30 micromol/L (P<0.05). CONCLUSION: Histamine can induce constriction of the intracortical blood vessels, which is mediated by H1 receptor.