title: Effect of gonadectomy and hypophysectomy on plasma steroid levels in male and female lampreys (Lampetra fluviatilis, L.).
abstract: Testosterone, estradiol, and dehydroepiandrosterone (T, E2, and DHA) were measured by RIA in plasma samples from three groups of sexually immature male and female (male, female) river lampreys: (I) intact, (II) gonadectomized, or (III) with pro- and mesoadenohypophysis removed (hypophysectomized). T levels were around 0.1 ng/ml in both I male and I female and increased significantly in all operated groups, especially in II male, to 1.2 ng/ml. E2 levels were between 0.7 and 1 ng/ml in I male and I female and were significantly elevated only in II male to 2.0 ng/ml. DHA levels showed significant decreases, from around 0.9 ng/ml in I male and I female, in both operated groups. It is suggested that T and E2 are secreted from a nongonadal source in both sexes and then converted to biologically active sex hormones in the gonads. Therefore T and E2 do not decrease, and may even accumulate, in the blood after gonadectomy. Since extirpation of the pro- and mesoadenohypophysis was not followed by a decrease in T and E2, their secretion may be stimulated by a hormone from another part of the pituitary such as the metaadenohypophysis.
mesh_terms: D000818:Animals; D002369:Castration; D003687:Dehydroepiandrosterone / Q000097:blood*; D004958:Estradiol / Q000097:blood*; D005260:Female; D006915:Hydroxytestosterones / Q000097:blood; D007016:Hypophysectomy; D007798:Lampreys; D008297:Male; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D012727:Sex Characteristics; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood*
chemical_list: D006915:Hydroxytestosterones; C037914:11-hydroxytestosterone; D013739:Testosterone; D003687:Dehydroepiandrosterone; D011374:Progesterone; D004958:Estradiol; C003600:11-ketotestosterone