From the Departments of Pharmacology (J.P.C., J.L.G., C.D.S.), Psychology (R.F.J., A.K.J.), and Anatomy and Cell Biology (M.D.C.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa.
Hypertension. 2014 Jul;64(1):141-8. doi: 10.1161/HYPERTENSIONAHA.114.03461. Epub 2014 Apr 28.
Angiotensin-II production in the subfornical organ acting through angiotensin-II type-1 receptors is necessary for polydipsia, resulting from elevated renin-angiotensin system activity. Protein kinase C and mitogen-activated protein kinase pathways have been shown to mediate effects of angiotensin-II in the brain. We investigated mechanisms that mediate brain angiotensin-II-induced polydipsia. We used double-transgenic sRA mice, consisting of human renin controlled by the neuron-specific synapsin promoter crossed with human angiotensinogen controlled by its endogenous promoter, which results in brain-specific overexpression of angiotensin-II, particularly in the subfornical organ. We also used the deoxycorticosterone acetate-salt model of hypertension, which exhibits polydipsia. Inhibition of protein kinase C, but not extracellular signal-regulated kinases, protein kinase A, or vasopressin V₁A and V₂ receptors, corrected the elevated water intake of sRA mice. Using an isoform selective inhibitor and an adenovirus expressing dominant negative protein kinase C-α revealed that protein kinase C-α in the subfornical organ was necessary to mediate elevated fluid and sodium intake in sRA mice. Inhibition of protein kinase C activity also attenuated polydipsia in the deoxycorticosterone acetate-salt model. We provide evidence that inducing protein kinase C activity centrally is sufficient to induce water intake in water-replete wild-type mice, and that cell surface localization of protein kinase C-α can be induced in cultured cells from the subfornical organ. These experimental findings demonstrate a role for central protein kinase C activity in fluid balance, and further mechanistically demonstrate the importance of protein kinase C-α signaling in the subfornical organ in fluid intake stimulated by angiotensin-II in the brain.
脑室内旁核中血管紧张素-II 的产生通过血管紧张素-II 型 1 受体作用，对于肾素-血管紧张素系统活性升高引起的多饮是必要的。已经表明蛋白激酶 C 和丝裂原活化蛋白激酶途径介导了脑内血管紧张素-II 的作用。我们研究了介导脑内血管紧张素-II 诱导多饮的机制。我们使用了由神经元特异性突触蛋白启动子控制的人肾素和由其内源启动子控制的人血管紧张素原组成的双转基因 sRA 小鼠，导致脑内血管紧张素-II 过度表达，特别是在室旁核。我们还使用了去氧皮质酮-盐高血压模型，该模型表现出多饮。蛋白激酶 C 的抑制，但不是细胞外信号调节激酶、蛋白激酶 A 或加压素 V₁A 和 V₂受体的抑制，纠正了 sRA 小鼠升高的水摄入量。使用同工型选择性抑制剂和表达显性负性蛋白激酶 C-α 的腺病毒表明，室旁核中的蛋白激酶 C-α 对于介导 sRA 小鼠升高的液体和钠摄入是必要的。蛋白激酶 C 活性的抑制也减弱了去氧皮质酮-盐模型中的多饮。我们提供的证据表明，中枢蛋白激酶 C 活性的诱导足以诱导水合状态下的野生型小鼠饮水，并且可以在室旁核培养细胞中诱导蛋白激酶 C-α 的细胞膜定位。这些实验发现表明中枢蛋白激酶 C 活性在液体平衡中起作用，并且进一步在脑内血管紧张素-II 刺激的液体摄入中证明了蛋白激酶 C-α 信号在室旁核中的重要性。
