Extremely high levels of corticosteroids and low levels of corticosteroid binding macromolecule in plasma of marmoset monkeys.

Marmoset monkeys were shown to have extremely high resting plasma corticosteroid levels compared to those of macaque monkeys and humans. A major component of corticosteroids seems to be cortisol. Levels of total 11-deoxy-17-KS in plasma of marmoset monkeys were very low (less than 0.01-0.04 microng/ml). Following the injection of ACTH, plasma corticosteroid levels of marmoset monkeys increased by 18-62% (at 1 h), and by 62-160% (at 2 h). Concentrations of plasma corticosteroid binding macromolecule in marmoset monkeys were extremely low (less than 10 nM). It was suggested that in these monkeys, the majority of plasma corticosteroids exists in non-protein bound forms.