AT_1受体在脑胆碱能刺激引起的延髓腹外侧部TH-IR变化中的作用

Effect of AT_1 receptor on changes of thyrosine hydroxylase-immunoreactivity in rostral ventrolateral medulla induced by brain cholinergic stimuli in rats

目的:探讨大鼠侧脑室注射胆碱能激动剂氨甲酰胆碱(carbachol,CBC)后引起的肾排钠量、肾小球滤过率、肾血浆流量的改变和延髓腹外侧部酪氨酸羟化酶免疫反应活性(thyrosinehydroxylase-immunoreactivity,TH-IR)的变化,以及氯沙坦(losartan,Los)阻断脑血管紧张素能AT1受体后对上述变化的影响。方法:选用SD雄性大鼠,随机分成4组:NS+CBC组、Los+CBC组、Los+NS组、NS+NS组,侧脑室注射氨甲酰胆碱(0.5μg)和/或氯沙坦(20μg)后,利用整体实验方法测定肾排钠量、肾小球滤过率、肾血浆流量;采用免疫组织化学方法观察大鼠延髓腹外侧部酪氨酸羟化酶免疫反应活性的变化。结果:与NS+NS组比,大鼠侧脑室注射氨甲酰胆碱(0.5μg)后40min,肾排钠量显著增加,延髓腹外侧部酪氨酸羟化酶免疫反应阳性神经元数目明显增多,免疫染色强度明显增加(P<0.05);与NS+CBC组比,氯沙坦预处理后大鼠肾排钠量显著下降,延髓腹外侧部酪氨酸羟化酶免疫反应阳性神经元数目明显下降,免疫染色强度明显降低(P<0.05)。此外,实验还观察到,侧脑室注射氨甲酰胆碱或氯沙坦对肾小球滤过率和肾血浆流量无明显影响(P>0.05)。结论:大鼠侧脑室给予氨甲酰胆碱后,可显著引起促钠排泄反应,对延髓腹外侧部的儿茶酚胺能神经元有兴奋作用;阻断脑血管紧张素能AT1受体可下调氨甲酰胆碱诱导的上述变化。

Objective: To investigate the effect of AT1 receptor on the changes of thyrosine hydroxylase-immunoreactivity(TH-IR) in rostral ventrolateral medulla(RVLM) induced by brain cholinergic stimuli in rats.Methods: Male SD rats were randomly divided into 4 groups: NS+CBC group,Los+CBC group,Los+NS group and NS+NS group.AT1 was blocked by pretreatment of 20 μg losartan in Los+CBC and Los+NS groups;intracerebroventricular injection of 0.5 μg carbachol was used for cholinergic stimuli in NS+CBC and Los+CBC groups;n...