title: Seasonal variations in parameters of milt production and in plasma concentration of sex steroids of male rainbow trout (Salmo gairdneri).
abstract: Concentrations of testosterone (T), 11-ketotestosterone (11-KT) and 17 alpha-hydroxy-20 beta-dihydroprogesterone (17 alpha 20 beta P) were measured by a direct radioimmunoassay technique in the plasma of male rainbow trout, Salmo gairdneri, from two winter-spawning strains and one autumn-spawning strain. There was no evidence that milt production, its volume and density or the ionic composition of the seminal plasma could be related to the levels of 11-KT or T. Peak plasma T levels were reached just before production of milt could first be detected by handstripping. The concentration of 17 alpha 20 beta P remained elevated throughout the period of milt production and there was evidence that this steroid might be associated with the control of the ionic composition of seminal plasma.
mesh_terms: D000818:Animals; D002414:Cations, Monovalent; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006908:Hydroxyprogesterones / Q000097:blood; D008297:Male; D011188:Potassium / Q000378:metabolism; D012487:Salmonidae / Q000502:physiology*; D012621:Seasons; D012661:Semen / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013091:Spermatogenesis; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood; D014337:Trout / Q000502:physiology*
chemical_list: D002414:Cations, Monovalent; D012739:Gonadal Steroid Hormones; D006908:Hydroxyprogesterones; C021012:17 alpha,20 beta-dihydroxypregn-4-en-3-one; D013739:Testosterone; D012964:Sodium; C003600:11-ketotestosterone; D011188:Potassium