Mechanism of heat acclimation-induced improvement of salivary secretion in rats

我们探讨了热暴露改善大鼠唾液功能的机制。热暴露两天后，大鼠颌下腺水通道蛋白(AQP)1和5mRNA的表达增加，同时HIF-1a途径被促进，导致血管内皮生长因子(VEGF)的诱导。热暴露2天或5天后，AQP1蛋白水平升高。热习服后AQP5在浆液性腺泡细胞的顶膜分布增强，而AQP1仅表达于颌下腺的内皮细胞。自发运动40d可使大鼠颌下腺AQP1蛋白水平升高，但对与AQP5诱导相关的TRPV1、V3或Na-K-ATPase的AQP5表达和蛋白水平无明显影响。匹罗卡品诱导的唾液分泌量略有增加。这些结果表明，在大鼠中，热暴露或运动促进唾液腺AQP的表达，这可能有助于改善唾液腺功能。

We investigated mechanism of heat exposure-induced improvement of salivary function in rats. Two-day heat exposure increased expressions of aquaporin (AQP)1 and 5 mRNA in submandibular glands of rats concomitant with the promotion of the HIF-1a pathway, leading to VEGF induction. The protein level of AQP1 was raised after 2 or 5 day-heat exposure. The apical membrane distribution of AQP5 in serous acinar cells enhanced after heat acclimation, while AQP1 expression was restricted to the endothelial cells in the submandibular glands. Spontaneous exercise for 40 days tended to elevate AQP1 protein level of the rat submandibular glands, whereas it failed to affect AQP5 expression and protein levels of TRPV1, V3 or Na-K ATPase, relating to induce AQP5. Pilocarpine-induced salibary secretion was slightly elevated. These results suggest that in rats, heat exposure or exercise facilitates AQP expression in salivary glands, which may then contribute to improving saliva gland function.