Effects of captivity stress on plasma steroid levels in the green frog, Rana esculenta, during the annual reproductive cycle

1. Androgen, 17beta-estradiol and corticosterone levels were measured by RIA in plasma of Rana esculenta frogs sampled in the field and in the laboratory. 2. Androgen and 17beta-estradiol annual cycles of frogs sampled in the field mirrored those of animals sampled in the laboratory 24 hr after capture; on the contrary the absolute values were not similar. 3. 17beta-estradiol levels showed a peak 6 hr after capture in the pre-reproduction and reproduction periods. 4. Corticosterone levels increased 72 hr after capture.