自发性高血压大鼠中脑导水管周围灰质nNOS阳性神经元的变化

目的观察自发性高血压大鼠(spontaneously hypertensiverats,SHR)中脑导水管周围灰质内神经元型一氧化氮合酶(neuronal nitric oxide synthase,nNOS)阳性神经元的变化。方法取SHR和京都种威斯特大鼠(Wistar-Koytorats,WKY)大鼠各30只,分别于3月(14周)龄,6月龄和12月龄测血压并处死,ABC免疫细胞化学方法显示nNOS阳性神经元。结果SHR血压随鼠龄的增长逐渐升高,于12～14周龄时血压在高位稳定,且均高于WKY大鼠(P<0.05)维持在[(20.8±1.1)～(26.3±1.0)]kPa(P<0.05);WKY大鼠各时期血压无明显差异,维持在[(13.7±1.6)～(15.1±1.7)]kPa。中脑导水管周围灰质nNOS阳性神经元以小细胞为主,突起有2-4个,许多朝中脑水管方向延伸。定量结果显示,SHR大鼠nNOS阳性神经元随着血压升高呈逐渐减少的趋势,12月龄与3月龄和6月龄相比均有显著差异(P<0.01),而各个时期WKY大鼠PAGnNOS阳性神经元均无明显变化。结论SHR中脑导水管周围灰质nNOS阳性神经元的减少可能通过影响延髓的血压调节中枢调控高血压的发生,并有可能与高血压的痛觉过敏有关。

Changes of neuronal nitric oxide synthase-immunopositive neurons in the midbrain periaqueductal gray of spontaneously hypertensive rats

Objective To observe the changes of neuronal nitric oxide synthase (nNOS) immunopositive neurons in the midbrain periaqueductal gray of spontaneously hypertensive rats. Methods Thirty SHRs and thirty Wistar-Koyto rats (WKYs) were sacrificed at the ages of 3 m (14 weeks), 6 months, and 12 months respectively to observe the changes of nNOS immunopositive neurons with ABC immunocytochemical assay. Result The blood pressure of SHR increased with the rise of age,and arrived at the highest position at 12～14 weeks. SHRs maintained significantly higher blood pressures from 20.8±1.1 and 26.3±1.0 kPa (P <0.05), gradually increasing during the development of hypertension, when no significant changes were observed in the blood pressure of WKY rats at the specified time points. The nNOS immunopositive neurons in the midbrain periaqueductal gray were of small sizes with long intersected nerve fibers. Some of the fibers extended to the central canal. The number of the positive neurons decreased with ages in SHRs, especially obvious at 12 m (P<0.01), which was significantly different from that in the WKYs(P<0.01). No significant changes were found in WKY rats. Conclusion The reduction of nNOS immunopositive neurons in the midbrain periaqueductal gray of SHRs might accelerate the development of hypertension by modulating the blood pressure centers of accommodation and maybe relate to the hyperpathia of hypertensive rats.