Sex steroids in plasma of lake whitefish Coregonus clupeaformis during spawning in Lake Erie

Lake whitefish, Coregonus clupeaformis, were collected from the Western bas in of Lake Erie during spawning. Free and conjugated (sulfated and glucuron idated) steroids including testosterone (T), 11-ketotestosterone (11-kT), e stradiol-17 beta (E2) and 17,20 beta -dihydroxy-4-pregnen-3-one (17,20 beta P) were measured in the plasma by radioimmunoassay. In males, the progressi on of spermiation was characterized by a significant decrease in plasma fre e steroids, whereas the levels of conjugated steroids remained similar and low, except for sulfated and glucuronidated testosterone. Plasma sex steroi ds did not correlate with the density or the motility of the spermatozoa. I n females, the concentration of plasma T was significantly higher in preovu lating than in ovulating females. The levels of E2 and 17,20 betaP in ovula ting lake whitefish exhibited large variations ranging from below detection limit to 0.9 ng ml(-1) and from 0.2 to 13 ng ml(-1), respectively. Analysi s of conjugated steroids revealed high levels of glucuronidated and sulfate d 17,20 betaP and glucuronidated T in females ovulating in December. Howeve r, no significant differences in the proportion of the conjugated steroids were observed. (C) 2001 Elsevier Science Inc. All rights reserved.