Muise Kristina A, Menzies Allyson K, Willis Craig K R
Department of Biology, University of Winnipeg, 515 Portage Ave, R3B 2E9 Winnipeg, Canada.
Department of Biology, University of Winnipeg, 515 Portage Ave, R3B 2E9 Winnipeg, Canada.
Physiol Behav. 2018 Oct 1;194:356-361. doi: 10.1016/j.physbeh.2018.06.003. Epub 2018 Jun 9.
Acute stressors such as capture and handling can elicit physiological responses in endothermic animals. One example of such a response is an increase in body temperature (T) commonly referred to as stress-induced hyperthermia (SIH). For species that employ torpor, typically an inactive state characterized by a controlled reduction in T and metabolic rate, a rapid increase in T could be advantageous, especially in the context of escape from predators. We quantified SIH in silver-haired bats (Lasionycteris noctivagans) because they readily enter torpor and often roost in exposed places where they could be vulnerable to predators. We tested the hypothesis that handling stress causes SIH in three separate contexts: a) during the nocturnal, active phase immediately following capture during flight, b) during the diurnal, inactive phase of normothermic bats, and c) during pronounced torpor immediately following exposure to cold ambient temperature. We used a standardized protocol during which T was measured (as rectal temperature) immediately upon handling and, again, several minutes later. We found that SIH occurred for inactive, normothermic bats held at a warm temperature. Surprisingly, however, handling stress caused a reduction in T for normothermic bats following the active, flight phase and, although in the opposite direction, this cooling rate was indistinguishable from the rate of SIH for normothermic bats during the rest phase. As expected, we observed a large change in T during rewarming from torpor following handling. This warming rate was greater than that previously reported in the literature for any heterothermic endotherm. Rapid rewarming by silver-haired bats could reflect their tendency to roost in relatively exposed locations that may be vulnerable to predators. This study provides new information on SIH in an under-studied group of animals and illustrates the need to evaluate the hypothesis that SIH and rewarming from torpor are influenced by predation risk and activity state.
诸如捕获和处理等急性应激源可引发恒温动物的生理反应。这种反应的一个例子是体温（T）升高，通常称为应激诱导性体温过高（SIH）。对于采用蛰伏状态（通常是一种以T和代谢率可控降低为特征的不活动状态）的物种来说，T的快速升高可能是有利的，特别是在逃避捕食者的情况下。我们对银毛蝙蝠（Lasionycteris noctivagans）的SIH进行了量化，因为它们很容易进入蛰伏状态，并且经常栖息在可能易受捕食者攻击的暴露场所。我们在三种不同情况下检验了处理应激会导致SIH的假设：a）在飞行中捕获后的夜间活跃阶段，b）在正常体温蝙蝠的白天不活动阶段，c）在暴露于寒冷环境温度后立即进入明显蛰伏状态时。我们使用了一个标准化方案，在处理后立即（作为直肠温度）测量T，并在几分钟后再次测量。我们发现，处于温暖温度下的不活动、正常体温的蝙蝠会出现SIH。然而，令人惊讶的是，处理应激导致正常体温的蝙蝠在活跃飞行阶段后体温降低，尽管方向相反，但这种降温速率与正常体温蝙蝠在休息阶段的SIH速率无法区分。正如预期的那样，我们观察到处理后从蛰伏状态复温期间T有很大变化。这种复温速率比之前文献中报道的任何异温性恒温动物的速率都要高。银毛蝙蝠的快速复温可能反映了它们倾向于栖息在相对暴露的位置，而这些位置可能易受捕食者攻击。这项研究为一组研究较少的动物的SIH提供了新信息，并说明了需要评估SIH和从蛰伏状态复温受捕食风险和活动状态影响这一假设。
