RESUMO
Glucocorticoids participate in the behavioral and physiological responses generated under stressful circumstances coming from different sources-physical and/or psychological. In mammals, the increases of these hormones are mediated by the activation of the hypothalamic-pituitary-adrenal axis. This response occurs after exposure to novel and unpredictable situations that lead to the loss of homeostasis, for example, a direct encounter with predators or their cues. However, the relationship between the physiological and behavioral responses is still a complex issue in vertebrates. We evaluate the effects of an experimental manipulation of glucocorticoid levels on the generation of the behavioral and physiological response to stress by predation in the subterranean rodent C. talarum. We found that when tuco-tucos encountered predator cues-fur odor, and largely, immobilization-they responded physiologically by secreting cortisol. This response was accompanied by an associated behavioral response. However, when the increase in plasma cortisol originated exogenously by the injection of cortisol, a behavioral response was not observed. Finally, inhibition of glucocorticoids' synthesis was effective in weakening the behavioral effects produced by immobilization. In conclusion, in tuco-tucos, predator cues act as stress factors that trigger differential increases in plasma cortisol and a behavioral response associated with the appearance of anxiety states.
Assuntos
Ansiedade/fisiopatologia , Comportamento Animal/fisiologia , Medo/fisiologia , Glucocorticoides/metabolismo , Sistema Hipotálamo-Hipofisário/fisiologia , Comportamento Predatório/fisiologia , Roedores/fisiologia , Animais , Masculino , Sistema Hipófise-Suprarrenal/fisiologia , Roedores/metabolismoRESUMO
In pregnant females, a failed predatory event not only induces individual responses but also represents a significant change in the developmental environment of the offspring, which may lead to modifications in their phenotype that may persist at different stages of life. We evaluate whether prenatal exposure to predatory cues affects anxiety behavior, behavioral response to predator cues, stress response to immobilization, and immune response to sheep red blood cells (SRBC) and phytohemagglutinin (PHA) in juveniles of the subterranean rodent Ctenomys talarum. We found that prenatal predator stress (PPS) (1) increased juvenile anxiety-like behaviors and the appearance of antipredator behaviors, (2) did not affect the response of offspring to predatory stressors, and (3) did not influence the physiological response of juveniles to stressors (immobilization) nor the immunological responses to SRBC and PHA challenges. This work shows the influence of PPS on the development of behavioral responses in the offspring, whom displayed a state of anxiety and behavioral changes associated with decreased locomotor activity and avoidance behaviors. Thus, these individuals prenatally exposed to predatory cues show behavioral adaptations that may contribute to avoid predators in the adult life.