Publication Abstract

Time course of release of pheromonallyactive gonadal steroids and their conjugates by ovulatory goldfish

A.P. Scott and P.W. Sorensen

Previousstudies have demonstrated that ovulatory goldfish synthesize and release a variety ofsteroids into the water, where some of them function as sex pheromones. Among the steroidswhich have been measured are free androstenedione, testosterone, 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P), 17α,20β,21-trihydroxy-4-pregnen-3-one (17,20β,21P), 17α-hydroxy-4-pregnene-3,20-dione (17-P), 11-deoxycortisol (17,21-P),and 17α, 20α-dihydroxy-4-pregnen-3-one(17,20α-P),glucuronidated testosterone, 17,20β-P, and 17,20β,21-P, and sulfated 17,21-P, 17,20β-P, and 17,20β,21-P. This study reports the changes inthe amounts of these steroids released into the water, at 3-hr intervals, by 12 femalegoldfish injected with human chorionic gonadotrophin (HCG). Eight fish ovulated. Theamounts of steroids released into the water were significantly higher in the fish whichovulated than in those which did not. The peak rate of release (ng per hour) of freeandrostenedione (91), glucuronidated testosterone (143), and sulfated 17,21-P (33)occurred at ca. 4 hr postinjection; free 17-P (163) and free 17,21-P (217) at ca. 6 hr.;free 17,20β-P (58)and free 17,20β,21-P(58) at ca. 7.5 hr; and glucuronidated 17,20β-P (96), glucuronidated 17,20β,21-P (264), sulfated 17,20β-P (64) and sulfated 17,20β,21-P (153) at ca. 9 hr. Amounts of all of the steroids were attheir lowest between 12 and 15 hr and, in the ovulated fish, had risen significantly againbetween 18 and 21 hr. The amounts of glucuronidated testosterone, 17,20β-P and 17,20β,21-P, and of sulfated 17,20β-P and 17,20β,21-P, in water exceeded thoseof free steroid. Elevated levels of free and glucuronidated steroids were also found inthe blood plasma of HCG-injected fish. Considerably more androstenedione than testosteronewas released into the water. Assessment of the "pheromonal effectiveness" ofeach steroid indicated that the free and sulfated forms of 17,20β-P and 17,20β,21-P, and androstenedione were the mostimportant pheromonal steroids released by female goldfish.

Reference:

A.P. Scott and P.W. Sorensen, 1994. Time course of release of pheromonally active gonadalsteroids and their conjugates by ovulatory goldfish. General and ComparativeEndocrinology, 96: 309-323.