Differential responses of cortisol and corticosterone to adrenocorticotropic hormone (ACTH) in a subterranean rodent (Ctenomys talarum)

VERA, FEDERICO; ZENUTO, ROXANA; ANTENUCCI, CARLOS DANIEL

JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL GENETICS AND PHYSIOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2012 vol. 317 p. 173 - 184

1932-5223

We aimed to evaluate the responses of cortisol, corticosterone and blood glucose to adrenocorticotropic hormone (ACTH) in males and females of the subterranean rodent Ctenomys talarum and addressed inter-annual variations in the plasma levels of both hormones. The most important results indicate that: (1) cortisol positively responds to the ACTH signal but corticosterone does not, even though corticosterone levels were higher than cortisol concentrations, (2) plasma corticosterone concentrations in freeliving animals were 20 times higher compared to values reported for the same population during previous annual periods and, as cortisol levels were similar, this resulted in much lower cortisol/corticosterone ratios, (3) cortisol and corticosterone differentiated in their relative proportions in plasma in free-living males and females. These results indicate that cortisol and corticosterone are differentially regulated in our study species and emphasize that a remarkable temporal variation in the relative proportions of these hormones may occur in natural populations. Therefore, the conclusions regarding the presence of cortisol and corticosterone in plasma of wild animals may differ substantially depending on the moment when the study is conducted. Recent data indicate that cortisol and corticosterone are not interchangeable hormones in species of free-living vertebrates. We suggest that, in addition to the classical roles of glucocorticoids (GCs), it is crucial that other physiological functions be kept in mind when interpreting GC data from wild species.