Is there an effect of environmental temperature on the response to an antigen and the metabolic rate in pups of the rodent Octodon degus?

ABSTRACT

Environmental temperature is a variable that influences all aspects of organisms, from physiological, e.g. immune function, and morphological traits to behavior. Recent studies have reported that environmental temperature modulates organisms' thermoregulatory capacity and immune response, suggesting that trade-offs must be made between thermoregulation and immune function. Despite this, studies that evaluate this trade-off in developing endotherms are scarce. The aim of this study was to evaluate the effects of environmental temperature experienced during development on the response to an antigen and its energetic costs in the precocial rodent Octodon degus. To accomplish this, we acclimated pups from birth to weaning at temperatures of 15°C and 30°C. At weaning, animals were inoculated with lipopolysaccharide (LPS) and cytokine interleukin-1ß levels, sickness behavior, changes in body temperature and basal metabolic rate, and body mass were measured. Our results showed that environmental temperature influences cytokine levels, body temperature, and some aspects of sickness behavior. Specifically, acclimatization at 30°C has a suppressive effect on the response to LPS, possibly due to a control to avoid overproduction of interleukin-1ß. Body mass and basal metabolic rate were not affected by environmental temperature experienced during development, but inoculation with LPS affected both variables. Our results suggest that ambient temperature may be a key factor that affects the response to an antigen in pups of O. degus; however, no evidence of a trade-off between thermoregulation and immune function was found here.