PI_3激酶参与AT_1受体介导Ang II调节SHR脑神经元电活动的信号转导

目的　探索AT1受体介导AngII调节SHR和WKY鼠脑神经元电活动的信号转导机制。 方法　原代培养SHR和WKY新生鼠脑干和下丘脑神经元 ,用全细胞膜片钳以电流箝方式记录神经元的放电活动 ,观察AngII及各种信号分子抑制剂对脑神经元放电频率的影响。结果　AngⅡ (10 0nmol·L-1)可使WKY新生鼠脑神经元的放电频率从 (0 .4 4± 0 .0 8)Hz增加到 (1.39± 0 .16 )Hz。这种效应在SHR鼠更加显著。由AngⅡ引起的这两种鼠脑神经元放电频率的增加均可被AT1受体拮抗剂Losartan完全消除。使用PKC抑制剂calphostinC和钙调蛋白激酶II抑制剂KN 93能完全阻断AngⅡ对WKY鼠脑神经元的作用 ,但对SHR鼠脑神经元的放电频率仅阻抑约 5 0 %。磷脂酰肌醇 3(PI3 )激酶抑制剂LY2 94 0 0 2 (10 μmol·L-1)对SHR鼠脑神经元的放电频率可产生部分阻断作用 ,但对WKY鼠脑神经元无明显影响。结论　AngII增加SHR和WKY鼠脑神经元放电频率的作用均由AT1受体介导。PI3 激酶在AngⅡ调节SHR鼠脑神经元电活动的信号转导机制中发挥重要作用

Role of PI3-kinase in the signal transduction mechanism of Ang II regulation mediated by AT1 receptor to firing activity of SHR neurons

Objective To investigate the signal transduction mechanism of Ang II regulation mediated by AT 1 receptor in brain neuron activities of SHR and WKY rats. Methods Primary neuron co-cultures were prepared from the hypothalamus and brainstem of newborn (one-day) SHR and WKY rats. Spontaneous or induced firing sparks of neurons were recorded with whole-cell patch clamp configuration in current clamp mode. Results Ang II increased the firing rate in the neurons of newborn SHR and WKY rats. The change in firing rate of SHR neurons was significantly (P<0.05) larger than that of WKY neurons. AngⅡ-induced increase in the firing rate of the neurons of both rats were completely blocked by using AT 1 receptor antagonist Losartan. PKC inhibitor calphostin C and CaMKII inhibitor KN-93 completely inhibited the firing spark of WKY neurons, but partly did that of SHR ones. PI 3-kinase inhibitor LY294002 partly inhibited the firing spark of SHR neurons, but did not affect that of WKY ones.Conclusion The action of AngⅡ's increasing the firing rate of SHR and WKY rat neurons is mediated by AT 1 receptor. PI 3-kinase plays an important role in the signal transduction mechanism of Ang II regulation mediated by AT 1 receptor to activity of SHR neurons.