Plasma concentrations of ovarian steroids in the freshwater European silver eel (Anguilla anguilla L.): effects of hypophysectomy and transfer to sea water

Abstract

Intact and hypophysectomized freshwater (FW) silver eels were transferred to tanks of FW or artificial sea water (SW; salinity = 0·60 osmol/l) which were simultaneously renewed twice a week. Fish were killed 2 months after transfer and plasma was assayed for ovarian steroids. In all fish, 5α-androstane-3β,17β-diol was present, while 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol were undetectable. In intact FW eels, plasma levels of testosterone, 5α-androstane-3β,17β-diol and oestradiol-17β were approximately 0·15 nmol/l. In intact SW eels, no change in plasma levels of testosterone and 5α-androstane-3β,17β-diol was found, whereas the concentration of oestradiol-17β was increased significantly (PPPPJ. Endocr. (1987) 114, 289–294