Plasma-sulfated C-21-steroids increase during the periovulatory period in female common wolffish and are influenced by temperature during vitellogenesis

Plasma concentrations of steroids during the periovulatory period were meas ured in female common wolffish reared at three different temperatures. Ster oids were quantified by radioimmunoassay (RIA). Two "broad-spectrum specifi city" RIAs-one which detects C-21-steroids with a 17,20 beta-dihydroxyl con figuration (17,20 beta-steroids) and the other which detects C-21-steroids with a 5 beta-reduced, 3 alpha-hydroxyl configuration (5 beta,3 alpha-stero ids)-picked up very large amounts of cross-reacting material (1.7 mu g ml(- 1) in one fish) in the sulfate fraction of plasma from ovulating females. R everse-phase highperformance liquid chromatography and thin-layer chromatog raphy revealed two major steroids: 5 beta-pregnane-3 alpha,17,20 beta-triol (80%) and 5 beta-pregnane-3 beta,17,20 beta-triol (20%). The sulfated form s of these steroids were elevated 4 to 6 days before and during ovulation, compared with those of females in vitellogenic and postspawning condition, in which concentrations were below 2.0 ng ml(-1). In the three groups of fi sh held at 4, 8, and 12 degrees C during vitellogenesis, but returned to 4 degrees C just prior to the spawning season, the mean concentrations of sul fated 17,20 beta-steroids in ovulating females were 530, 635, and 325 ng ml (-1), respectively. The corresponding concentrations of free 17,20 beta-dih ydroxy-4-pregnen-3-one (17,20 beta-P; the maturation-inducing steroid in ma ny teleosts) were 0.88, 0.86, and 0.57 ng ml(-1), respectively. Only minute amounts of 17,20 beta,21-P and its sulfated derivatives were detected. Sig nificantly lower steroid concentrations in the 12 degrees C group indicate that steroid synthesis and/or metabolism during the periovulatory period ar e influenced by the temperature experienced during vitellogenesis. In male fish, plasma concentrations of both sulfated 17,20 beta-steroids and free 1 7,20 beta-P were low (<2.0 ng ml(-1)) at all times. (C) 2000 Academic Press .