Desert rodents are faced with many challenges such as high dietary salt in their natural habitats and they have evolved abilities to conserve water and tolerate salt. However, the physiological and molecular mechanisms involved in water and salt balances in desert rodents are unknown. We hypothesized that desert rodents regulated water and salt balances by altering the expression of AQP2 and α-ENaC in the kidney. Mongolian gerbils (Meriones unguiculatus), a desert species, were acclimated to drinking water with different salt contents: (0, control; 4% NaCl, moderate salt, MS; 8% NaCl, high salt, HS) for 4 weeks. The gerbils drinking salty water had lower body mass, food intake, water intake, metabolic water production and urine volume. The HS gerbils increased the expression of arginine vasopressin (AVP) in the hypothalamus, and also enhanced the expression of AQP2 and cAMP/PKA/CREB signaling pathway in the kidney. In addition, these gerbils reduced serum aldosterone levels and α-ENaC expression in the kidney. Creatinine clearance was lower in the HS group than that in the control group, but serum and urine creatinine levels did not change. These data indicate that desert rodents rely on AVP-dependent upregulation of AQP2 and aldosterone-dependent downregulation of α-ENaC in the kidney to promote water reabsorption and sodium excretion under high salt intake.

中文翻译：

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蒙古沙鼠高盐摄入维持水盐稳态的生理和分子机制

沙漠啮齿动物面临着许多挑战，例如自然栖息地的高盐饮食，它们已经进化出保存水和耐盐的能力。然而，沙漠啮齿动物水盐平衡所涉及的生理和分子机制尚不清楚。我们假设沙漠啮齿动物通过改变肾脏中 AQP2 和 α-ENaC 的表达来调节水盐平衡。沙漠物种蒙古沙鼠 (Meriones unguiculatus) 适应不同盐含量的饮用水：（0，对照；4% NaCl，中盐，MS；8% NaCl，高盐，HS）4 周。喝盐水的沙鼠体重、食物摄入量、水摄入量、代谢水产生量和尿量均较低。HS沙鼠增加了下丘脑中精氨酸加压素（AVP）的表达，并且还增强了肾脏中 AQP2 和 cAMP/PKA/CREB ​​信号通路的表达。此外，这些沙鼠降低了肾脏中的血清醛固酮水平和 α-ENaC 表达。HS组肌酐清除率低于对照组，但血清和尿肌酐水平没有变化。这些数据表明，沙漠啮齿动物依靠 AVP 依赖性 AQP2 上调和醛固酮依赖性下调 α-ENaC 来促进高盐摄入下的水重吸收和钠排泄。