title: Involvement of gonadotrophin and steroid hormones in spermiation in the amago salmon, Oncorhynchus rhodurus, and goldfish, Carassius auratus.
abstract: Effects of intraperitoneal injections of chum salmon gonadotrophin (SGA) and various steroid hormones (17 alpha, 20 beta-dihydroxy-4-pregnen-3-one; 17 alpha,20 beta-diOHprog, 17 alpha-hydroxy-progesterone, testosterone, 11-ketotestosterone) on the induction of in vivo spermiation were examined in nonspermiating amago salmon (Oncorhynchus rhodurus) and goldfish (Carassius auratus). A single injection of SGA to amago salmon and two successive injections to goldfish induced strong spermiation responses. Similarly two successive injections of 17 alpha,20 beta-diOHprog caused precocious spermiation in both species; however, the response to 17 alpha,20 beta-diOHprog was of lesser magnitude than that to SGA. The spermiation response of goldfish to 17 alpha-hydroxyprogesterone was similar to that of 17 alpha,20 beta-diOHprog. Neither testosterone nor 11-ketotestosterone were effective in inducing spermiation in amago salmon, but these steroids were found to be slightly effective in goldfish. Effects of a single injection of SGA on changes in serum levels of 17 alpha,20 beta-diOHprog and 11-ketotestosterone were also examined in nonspermiating amago salmon. Serum levels of 17 alpha,20 beta-diOHprog dramatically increased after treatment and peaked on Day 2 and thereafter declined quickly. Similarly, 11-ketotestosterone peaked on Day 2, but the levels remained high throughout the experimental period. Considered together, these findings are consistent with the suggestion that 17 alpha, 20 beta-diOHprog is involved in the process of spermiation in teleosts. It is further suggested that this hormone is a testicular steroidal mediator of gonadotrophin-induced spermiation in amago salmon.
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000502:physiology*; D006054:Goldfish / Q000502:physiology*; D012739:Gonadal Steroid Hormones / Q000097:blood / Q000502:physiology*; D006062:Gonadotropins / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D012474:Salmon / Q000502:physiology*; D012661:Semen / Q000502:physiology*; D013997:Time Factors
chemical_list: D012739:Gonadal Steroid Hormones; D006062:Gonadotropins