Abstract
The glucocorticoid stress response is frequently used to indicate vertebrate response to the environment. Body temperature may affect glucocorticoid concentrations, particularly in ectotherms. We conducted lab manipulations and field measurements to test the effects of body temperature on plasma corticosterone (predominant glucocorticoid in reptiles) in eastern fence lizards (Sceloporus undulatus). First, we acclimated lizards to one of 4 treatments: 22 °C, 29 °C, 33 °C, or 36 °C, and measured cloacal temperatures and plasma corticosterone concentrations at baseline and after exposure to a standardized stressor (cloth bag). Both baseline and stress-induced corticosterone concentrations were lower in lizards with lower body temperatures. Second, we acclimated lizards to 22 °C or 29 °C and exposed them to a standardized (cloth bag) stressor for 3 to 41 min. Lizards acclimated to 29 °C showed a robust increase in plasma corticosterone concentrations with restraint stress, but those at 22 °C showed no such increases in corticosterone concentrations. Third, we measured lizards upon capture from the field. There was no correlation between body temperature and baseline plasma corticosterone in field-caught lizards. These results suggest body temperature can significantly affect plasma corticosterone concentrations in reptiles, which may be of particular concern for experiments conducted under laboratory conditions but may not translate to the field.
Highlights
The glucocorticoid stress response is frequently used to indicate vertebrate response to the environment
We examine the effects of temperature on the function of the HPA axis and subsequent secretion of plasma CORT in the ectothermic eastern fence lizard (Sceloporus undulatus)
This species is a model for studying physiology[17,18,19] and is widely used in studies exploring the effects of stressor exposure and CORT on physiology20–22, immunity[23,24,25], survival and r eproduction[26,27], and offspring m orphology[20,28] in a laboratory environment—studies which are often performed at room temperature
Summary
The glucocorticoid stress response is frequently used to indicate vertebrate response to the environment. Temperature affects CORT secretion in mammals; for example, at low body temperatures, sheep[13] and dogs[14] had a reduced stress response to physiological trauma as measured by plasma CORT concentrations. We examine the effects of temperature on the function of the HPA axis and subsequent secretion of plasma CORT in the ectothermic eastern fence lizard (Sceloporus undulatus) This species is a model for studying physiology[17,18,19] and is widely used in studies exploring the effects of stressor exposure and CORT on physiology20–22, immunity[23,24,25], survival and r eproduction[26,27], and offspring m orphology[20,28] in a laboratory environment—studies which are often performed at room temperature. Other studies performed in the field, Scientific Reports | (2020) 10:16315
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