The in vitro investigation of four radioactive corticosteroids in the antarctic seal ( Leptonychotes weddellii)

Adrenals from six specimens of Weddell seal were incubated at different time intervals in the presence of tritiated pregnenolone and/or progesterone- 14C. Cortisol, corticosterone, and 18-OH-corticosterone were characterized and found to be present in important amounts, progesterone being a better precursor for all three metabolites than pregnenolone. In spite of exhaustive efforts, aldosterone could not be detected in any of the six specimens. Percentage yields of the three steroids analyzed varied from animal to animal, but time curves showed reproducible shapes: the values for tritiated and 14C-corticosterone could be adjusted to a logarithmically descending function; those for tritiated and 14C-cortisol showed a maximum at 30 min and then also descended logarithmically; those for tritiated and 14C-18-OH-corticosterone were typical for an end product. The yields of 18-OH-corticosterone, as compared to those of corticosterone in each specimen, were high, an unusual observation among mammals showing very low yields or absence of aldosterone.