Corticosterone during the annual reproductive cycle and in sexual behavior in the crested newt, Triturus carnifex.

To clarify the role of corticosterone in the male and female crested newt, Triturus carnifex, and the possible involvement of this hormone in the reproductive processes, we monitored the seasonal and daily pattern of this corticosteroid; in addition, corticosterone, testosterone, and 17 beta-estradiol plasma levels were evaluated during the various phases of courtship. In both sexes, the seasonal pattern of corticosterone in plasma showed two peaks: one in winter, at the beginning of the reproduction, and the other one in summer, when the newts leave the pond. The corticosterone daily pattern showed a peak at 05:00 PM. During courtship, corticosterone was lower and testosterone higher in "inactive" male newts than in the courting animals, while estradiol was highest during the approach; in the females corticosterone was lower in "nonreceptive" animals than in "receptive" ones, and sex steroids did not show any difference. These data suggest that corticosterone is involved in the reproductive processes in male and female crested newts.