Moeller Karla T, Demare Guillaume, Davies Scott, DeNardo Dale F
School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
School of Geography & the Environment, University of Oxford, Oxford OX1 3QY, UK.
J Exp Biol. 2017 Jun 15;220(Pt 12):2166-2174. doi: 10.1242/jeb.150367. Epub 2017 Apr 21.
The physiological challenges associated with dehydration can induce an increase in plasma glucocorticoid concentrations, a response thought to provide the mechanism for dehydration suppressing immune function. However, a comprehensive examination of the inter-relationship of dehydration, stress and immune function has not been conducted within a single species. We previously demonstrated that Gila monsters (), which inhabit a xeric environment with a predictable seasonal drought, have enhanced measures of innate immunity when dehydrated. These results suggest that, in this species, dehydration may not induce a glucocorticoid response, but, instead, enhances physiological defense mechanisms. To explore this possibility, we examined multiple measures of innate immunity as well as initial and reactive plasma concentrations of glucocorticoids in captive and free-ranging Gila monsters at various hydration states. Our results show that, in this species, dehydration alone does not cause a substantial increase in plasma glucocorticoids, and we provide broader evidence that dehydration enhances defensive mechanisms including stress reactivity and various measures of innate immune function. These findings suggest that physiological responses to dehydration may depend heavily on an organism's ecology. More research on the effects of dehydration on the glucocorticoid response and immunity will help clarify the interactive roles they play in response to hydration challenges and whether adaptations to water-limited environments influence these interactions.
与脱水相关的生理挑战会导致血浆糖皮质激素浓度升高，这种反应被认为是脱水抑制免疫功能的机制。然而，尚未在单一物种内对脱水、应激和免疫功能之间的相互关系进行全面研究。我们之前证明，生活在干旱环境且季节性干旱可预测的吉拉毒蜥在脱水时具有更强的先天免疫能力。这些结果表明，在这个物种中，脱水可能不会引发糖皮质激素反应，而是增强生理防御机制。为了探究这种可能性，我们检测了处于不同水合状态的圈养和野生吉拉毒蜥的多种先天免疫指标以及糖皮质激素的初始和反应性血浆浓度。我们的结果表明，在这个物种中，仅脱水不会导致血浆糖皮质激素大幅增加，并且我们提供了更广泛的证据表明脱水会增强防御机制，包括应激反应性和多种先天免疫功能指标。这些发现表明，对脱水的生理反应可能在很大程度上取决于生物体的生态环境。更多关于脱水对糖皮质激素反应和免疫影响的研究将有助于阐明它们在应对水合挑战中所起的相互作用，以及对水有限环境的适应是否会影响这些相互作用。
