CORTICOSTEROIDOGENESIS IN THE FRESH WATER AND SALINE-MAINTAINED DUCK (ANAS PLATYRHYNCHOS)

Abstract

SUMMARY: No differences were observed in the patterns of adrenal steroidogenesis in vitro by ducks maintained on fresh water or on a hypertonic salt solution. Determinations in vivo of the biological half-life of corticosterone showed no significant difference between ducks maintained on or loaded with saline and fresh water controls. An increase in the apparent volume of distribution of corticosterone was, however, observed in birds loaded with the salt solution after maintenance on fresh water or salt solution. Estimations were made of the secretory rate of corticosterone in vivo. In the ducks maintained on the salt solution an increased adrenal weight was responsible for the enhanced secretory rate but ducks maintained on fresh water and loaded with saline secreted corticosterone at a higher rate per unit weight of adrenal. The implications of the increased rate of corticosterone secretion are discussed in relation to the known dependence of nasal gland function in marine birds on a functional adrenal gland.