Gonadotropic regulation of androgen production in flounder and salmonids

Abstract

Maturational hormones, prepared from pituitaries of winter flounder ( Pseudopleuronectes americanus), American plaice (Hippoglossoides platessoides), carp ( Cyprinus carpio), and chum salmon ( Oncorhynchus keta), and characterized by adsorption on Con A-Sepharose, reinitiated the production of 11-ketotestosterone and testosterone by hypophysectomized male winter flounder. Stimulation of 11-ketotestosterone could be observed 24 and 48 hr after a single injection of flounder maturational hormone. Hypophysectomy resulted in a disappearance from the circulation of sex hormone-binding protein which could be restored by both maturational and vitellogenic hormones. The flounder maturational hormone also induced spermiation and ovulation while 17α-hydroxyprogesterone stimulated oocyte maturation with no ovulation. The vitellogenic hormones prepared from the fractions of flounder, plaice, and salmon pituitary extracts unadsorbed on Con A-Sepharose, had no androgenic activity and did not evoke spermiation or oocyte maturation, but were able to stimulate the incorporation of serum phosphoprotein(s) into ovarian yolk. An antiserum against flounder maturational hormone lowered the plasma level of testosterone in female flounder. The salmon maturational hormone induced synthesis of androgens in intact juvenile rainbow trout ( Salmo gairdneri) of both sexes and resulted in a predominance of 11-ketotestosterone in the males and testosterone in the females. Treatment of intact mature male landlocked salmon ( Salmo salar sebago), with an antiserum to the chum salmon maturational hormone, led to a dramatic decrease of 11-ketotestosterone in the circulation. A combination of glycosidases, including neuraminidase, glucosaminidase, galactosidase, and mannosidase, had no effect on the immunological activities of salmon and flounder maturational hormones.