The impact of reproduction on the stress axis of free-living male northern red backed voles (Myodes rutilus)

摘要: Activation of the hypothalamic–pituitary–adrenal (HPA) axis culminates in release glucocorticoids (henceforth CORT), which have wide-reaching physiological effects. Three hypotheses potentially explain seasonal variation CORT. The enabling hypothesis predicts that reproductive season CORT exceeds post-reproductive because enables investment. inhibitory opposite can negatively affect function. costs reproduction HPA condition declines over and following season. We tested these wild male red-backed voles (Myodes rutilus) during seasons. quantified levels response to restraint stress tests consisting three blood samples (initial, stress-induced, recovery). Mineralocorticoid (MR) glucocorticoid (GR) receptor mRNA brain were also Total (tCORT) initial stress-induced greater than season, supported hypothesis. Conversely, free (fCORT) did not differ between seasons, was counter both hypotheses. Evidence for decline as well GR MR (i.e. hypothesis) mixed. Moreover, all parameters showed signs declining show suggesting resulting from investment had subsided. In conclusion, our results suggest different aspects respond differently changes