Department of Pharmacology, School of Medicine, CHA University, Bundang-gu, Seongnam, Gyeonggi-do, South Korea.
J Physiol Pharmacol. 2012 Feb;63(1):87-94.
It is important to understand the mechanism on the fluid shift and volume regulation occurring in astronauts after spaceflight for future life in space. In the present study, we examined the time-dependent alteration of anti-diuretic hormone (ADH) concentrating on the water reabsorption system in hindlimb unloaded rats. Male Sprague-Dawley rats were hindlimb unloaded for 1 (HU1), 7(HU7), 14 days (HU14) or rested in the ground for 3 days after HU14 (HU14+3). The plasma ADH and angiotensin II level showed peak value at HU7, and the alterations were restored at HU14. However, several serum electrolytes (Na, K, Cl) were not changed regardless of HU period. In the immunohistochemical study, we examined that ADH and c-Fos immunoreactivities (IR) were maximized at HU7 in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). Aquaporin 2 (AQP2) IR also was increased in the renal collecting duct for water re-absorption at HU7 showing a similar pattern with ADH. These results present a series of physiological ADH system alteration following to period of hindlimb unloading stimulus, indicating that ADH system is activated significantly at HU7. In addition, our results suggest that ADH system activation may be involved in anti-diuretic phenomenon in early spaceflight period. Furthermore, it is speculated that ADH system may require 14 days for adaptation to microgravity.
了解宇航员在太空飞行后液体转移和体积调节的机制对于未来的太空生活非常重要。在本研究中，我们研究了抗利尿激素（ADH）集中在下肢去负荷大鼠水重吸收系统中的时间依赖性改变。雄性 Sprague-Dawley 大鼠下肢去负荷 1 天（HU1）、7 天（HU7）、14 天（HU14）或在 HU14 后休息 3 天（HU14+3）。血浆 ADH 和血管紧张素 II 水平在 HU7 时达到峰值，变化在 HU14 时恢复。然而，无论 HU 期如何，几种血清电解质（Na、K、Cl）均未发生变化。在免疫组织化学研究中，我们发现在室旁核（PVN）和视上核（SON）中，ADH 和 c-Fos 免疫反应性（IR）在 HU7 时达到最大值。水重吸收的肾集合管中 AQP2 IR 也增加，与 ADH 呈现相似的模式。这些结果表明，在下肢去负荷刺激后的一段时间内，ADH 系统发生了一系列生理变化，表明 ADH 系统在 HU7 时显著激活。此外，我们的结果表明，ADH 系统的激活可能参与了早期航天飞行期间的抗利尿现象。此外，推测 ADH 系统可能需要 14 天才能适应微重力。
