Taylor K, Mayer L P, Propper C R
Northern Arizona University, Department of Biological Sciences, Flagstaff 86011, USA.
Physiol Behav. 1999;65(4-5):717-21. doi: 10.1016/s0031-9384(98)00227-3.
The behavioral response to dehydration is critical to an animal's survival. Because of their permeable skin, amphibians are particularly sensitive to dehydrating conditions. We tested the hypothesis that different forms of dehydration induce water absorption response (WR) behavior in the desert spadefoot toad, Scaphiopus couchii. First, we determined the behavioral response to intracellular dehydration by treating fully hydrated toads with increasing concentrations of hypertonic solutions of NaCl or sucrose via intraperitoneal injection (i.p.). Animals that were treated to induce intracellular dehydration with either solute exhibited a significant increase in WR behavior compared to vehicle-treated controls. To distinguish that the response was a result of an increased osmotic gradient between the intra- and extracellular compartments, we treated fully hydrated animals i.p. with urea, which freely passes into the intracellular compartment and increases overall animal osmolarity. Urea treatment did not induce WR behavior. To determine the response to extracellular dehydration, the blood volume of fully hydrated toads was reduced via cardiac puncture, and the WR behavior was measured. Animals who had a reduction in blood volume exhibited a significant increase in WR behavior compared to sham-punctured controls. Our results are the first to demonstrate that multiple forms of dehydration can induce thirst-related behavior in amphibians.
对脱水的行为反应对动物的生存至关重要。由于两栖动物的皮肤具有渗透性，它们对脱水环境特别敏感。我们测试了这样一个假设：不同形式的脱水会在沙漠锄足蟾（Scaphiopus couchii）中诱发吸水反应（WR）行为。首先，我们通过腹腔注射（i.p.）用浓度递增的NaCl或蔗糖高渗溶液处理完全水合的蟾蜍，来确定对细胞内脱水的行为反应。与用赋形剂处理的对照组相比，用任何一种溶质处理以诱导细胞内脱水的动物的WR行为都显著增加。为了区分这种反应是细胞内和细胞外区室之间渗透梯度增加的结果，我们对完全水合的动物进行腹腔注射尿素，尿素可自由进入细胞内区室并增加动物的总体渗透压。尿素处理并未诱发WR行为。为了确定对细胞外脱水的反应，通过心脏穿刺减少完全水合蟾蜍的血容量，并测量WR行为。与假穿刺对照组相比，血容量减少的动物的WR行为显著增加。我们的结果首次证明多种形式的脱水可在两栖动物中诱发与口渴相关的行为。
