Changes in steroid concentration in blood of female Tilapia aurea (teleostei, cichlidae) during initiation of spawning.

Steroids were quantitatively determined in blood of females of a bony fish, Tilapia aurea, before and after initiation of spawning. The steroids were determined by acetylatihg them with labeled acetic anhydride, collecting the acetates from a gas-liquid chromatographic column and by achieving constant specific activity of 3 derivatives prepared from the steroid acetates. By initiation of spawning the following changes in concentrations of these steroids were noted: testosterone increased 8-fold; 11-ketotestosterone increased 2.6-fold; 11²-hydroxytestosterone was detected only after initiation of spawning, and the concentration of deoxycorticosterone, a steroid postulated to be of importance in triggering ovulation, was found to increase 38-fold. No estradiol-17² was detected, although thoroughly looked for. These changes in steroid concentration in blood following initiation of reproductive activity point to the possible importance of steroids as hormones of reproduction in teleosts. (Endocrinology 95: 96...