Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2010 Dec;157(4):377-81. doi: 10.1016/j.cbpa.2010.08.009. Epub 2010 Aug 12.
Terrestrial amphibians obtain water by absorption across a specialized region of the ventral skin and exhibit a behavior, the water absorption response (WR) to place that region in contact with moist surfaces. Spadefoot toads (Scaphiopus couchii) spend dry months of the year in burrows, then emerge during brief periods of summer rainfall and seek water sources for rehydration and reproduction. We tested the hypothesis that these toads have changes in plasma and/or central angiotensin concentrations that are associated with seasonal emergence and WR behavior. Immunoreactive concentrations of combined angiotensin II and III (ir-ANG) were measured in plasma samples and microdissected regions of brain tissue taken from toads moving across the road or toads showing WR behavior in shallow puddles on the road. Plasma ir-ANG concentrations were not significantly different between these groups, but were significantly higher in the periventricular region of the hypothalamus in toads showing WR behavior. Concentrations in other brain regions, while highly variable among individuals, were not different between groups. Within the context of the natural history of a specialized desert toad, these results support the hypothesis that ir-ANG is associated with WR behavior in spadefoot toads in a manner analogous to oral drinking exhibited by other vertebrate clades.
陆生两栖动物通过腹部皮肤的一个特殊区域吸收水分，并表现出一种行为，即水分吸收反应（WR），将该区域与潮湿表面接触。蟾蜍（Scaphiopus couchii）在一年中的干旱月份会躲在洞穴里，然后在夏季短暂的降雨期间出现，并寻找水源进行补水和繁殖。我们测试了以下假设：这些蟾蜍的血浆和/或中枢血管紧张素浓度会发生变化，与季节性出现和 WR 行为有关。我们测量了在穿越道路的蟾蜍或在道路浅水坑中表现出 WR 行为的蟾蜍的血浆样本和脑组织微切割区域中结合血管紧张素 II 和 III（ir-ANG）的免疫反应浓度。这两组之间的血浆 ir-ANG 浓度没有显著差异，但在表现出 WR 行为的蟾蜍的下丘脑室周区域中，ir-ANG 浓度显著升高。尽管个体之间的浓度差异很大，但其他脑区的浓度在两组之间没有差异。在特殊沙漠蟾蜍的自然历史背景下，这些结果支持了 ir-ANG 与蟾蜍 WR 行为有关的假设，这与其他脊椎动物类群表现出的口服饮水行为类似。
