Aquaporin-5 (AQP5) water channel, transmembrane protein 16A (TMEM16A) Ca²⁺-activated Cl⁻ channel, and Na⁺-K⁺-2Cl⁻ cotransporter (NKCC1) are membrane proteins on salivary gland acinar cells that function in watery saliva secretion. We examined their expression changes in rat parotid glands under reduced mastication. Rats were either fed regular chow as a control group, fasted for 48 hr or fed a liquid diet for 48 hr or 1 week to reduce mastication. The parotid glands were then resected to analyze the protein and mRNA levels by immunofluorescence, immunoblotting, and reverse-transcription quantitative PCR (RT-qPCR). AQP5 protein was significantly decreased in both liquid diet groups and the fasting group but its mRNA levels showed no apparent changes compared with the control group. The protein and mRNA levels of TMEM16A and NKCC1 showed no significant changes between any of the groups other than an increase in NKCC1 mRNA in the 1-week liquid diet group. These results suggest that reduced mastication may increase the AQP5 protein degradation, but not that of other membrane proteins necessary for saliva secretion.

Aquaporin-5 (AQP5) 水通道、跨膜蛋白 16A (TMEM16A) Ca ²⁺ -激活的 Cl ^-通道和 Na ⁺ -K ⁺ -2Cl ^-协同转运蛋白 (NKCC1) 是唾液腺腺泡细胞上的膜蛋白，在水样唾液中发挥作用分泌。我们检查了咀嚼减少时大鼠腮腺中它们的表达变化。大鼠要么喂常规食物作为对照组，禁食 48 小时，要么喂流质饮食 48 小时或 1 周以减少咀嚼。然后切除腮腺，通过免疫荧光、免疫印迹和逆转录定量 PCR (RT-qPCR) 分析蛋白质和 mRNA 水平。流质饮食组和禁食组的AQP5蛋白均显着降低，但其mRNA水平与对照组相比没有明显变化。除了 1 周流质饮食组中 NKCC1 mRNA 增加外，各组之间 TMEM16A 和 NKCC1 的蛋白质和 mRNA 水平均没有显着变化。这些结果表明，咀嚼减少可能会增加 AQP5 蛋白的降解，但不会增加唾液分泌所需的其他膜蛋白的降解。