CONTROL OF SALIVARY SECRETION BY CENTRAL MECHANISMS OF BODY FLUID BALANCE AND DRINKING IN THE HYPOTHALAMUS

血浆渗透压升高包括唾液和粘液分泌减少，然后这些分泌减少会引起口渴。然而，体液平衡的中枢机制和唾液分泌之间的潜在关系尚不清楚。最近的一大堆研究揭示了体内水分平衡的中央控制系统，主要是通过一种啮齿动物。另一方面，有关唾液分泌机制的研究已经通过人、牛、羊和狗等大型动物完成。这项研究的目的是研究中枢渗透感受如何与唾液分泌有关，通过使用大鼠，大鼠是一个已经很好地理解了体液平衡的中枢机制。我们观察了进食一定重量的颗粒所需的时间和食物摄入过程中分泌的唾液量。然后，我们评估了24小时脱水治疗、腹腔注射高渗盐水(0.9%和5%)和脑室注射高渗液(1M NaCI、0.9M甘露醇)对这些值的影响。秘而不宣的萨？IVA是从插入腮腺导管的聚乙烯管中采集的。腹腔注射5%NaCI和侧脑室注射1M NaCI和0.9M甘露醇可延长进食一粒的时间。期间唾液分泌量无变化或略有增加。另一方面，脱水24小时的大鼠唾液分泌量和分泌率增加。这些结果表明，急性给予高渗溶液会激活中枢神经系统的渗透压感受器，这种激活会减少腮腺的唾液分泌。另一方面，脱水24小时后唾液分泌的增加可能意味着味觉和触觉等多个因素的参与。

Increased plasma osmolarity incudes decreased secretion of saliva and mucus and then these decreased secretion causes thirst sensation. However, it is not clear a relationship underlying between central mechanism of body fluid balance and salivary secretion. A pile of recent studies reveal a central control system of water balance in the body, by mainly using a species of rodents. On the other hand, studies concerning to the mechanisms of salivary secretion have been accomplished by using big animals such as human beings, cows, sheep and dogs. The purpose of this study is to address how a central osmoreception is related to salivary secretion, by using rats which is a species that the central mechanism of body fluid balance has been well understood. We observed the time required to eat a certain weight of pellet and a volume of saliva secreted during the food intake. Then we evaluated how these values were changed with treatment of 24 hours dehydration, intraperitoneal injection of hypertonic saline (0.9 % and 5 %) and intracerebroventricular injection of hypertonic solution ( 1M NaCI, 0.9 M mannitol ). The secreted sa? iva was collected from a polyethylene tube which was cannulated to a duct of the parotid gland. The time required to eat a pellet prolonged with the intraperitoneal injection of 5 % NaCI and the intracerebroventricular injection of 1 M NaCI and O.9 M mannitol. The volume of salivary secretion during the period showed no change or increased a little. On the other hand, 24 hours dehydrated rats showed an increased volume and rate of salivary secretion. Taken from these results, it is suggested that acute administration of hypertonic solution activates osmoreceptors in the central nervous system and this activation decreases salivary secretion from the parotid glands. On the other hands, enhancement of salivary secretion after 24 hours dehydration may imply an involvement of several factors such as taste and tactile sense.