Publication Abstract

Dynamics of excretion of 17,20ß-dihydroxy-4-pregnen-3-one 20-sulphate, and of the glucuronides of testosterone and 17ß-oestradiol, by urine of reproductively mature male and female rainbow trout (Oncorhynchus mykiss)

Dynamics of excretion of17,20ß-dihydroxy-4-pregnen-3-one 20-sulphate, and of the glucuronides of testosterone and17ß-oestradiol, by urine of reproductively mature male and female rainbow trout (Oncorhynchusmykiss)

A.P. Scott and N.R. Liley

Levels ofsulphated 17α,20β-dihydroxy-d-pregnen-3-one(17,20β-P; theoocyte maturation inducing steroid) in blood plasmas of sexually mature male and femalerainbow trout Oncorhynchcrs mykiss, were very low in comparison to those of thefree steroid. However, relatively large amounts were found in urine of both sexes.

Catheters were inserted into the urinarybladders of unovulated and ovulated females and of ripe-running males, and the fish thenplaced in spawning channels. Three-hourly urine samples were collected between 09.00 and18.00 hours and then a 15-h sample between 18.00 and 09.00 hours the next morning.Measurements were made of 17,20β-P-sulphate, testosterone glucuronide (T-G) and 17β-oestradiol glucuronide (E2-G).In females, the highest rates of excretion of E2-G, T-G and 17,20/3-P-sulphate were foundin unovulated, ovulating and ovulated females, respectively. The rates of excretion of17,20β-P-sulphate,T-G and E2-G in ovulated females were unaffected by the presence of a male. In males,however, there was a sharp increase in the rate of excretion of 17,20β-P-sulphate and T-G in fish which werepaired with an ovulated (nesting) female. A similar increase was found in males injectedwith male trout pituitary extract.

Reference:

A.P. Scott and N.R. Liley, 1994. Dynamics of excretion of17,20ß-dihydroxy-4-pregnen-3-one 20-sulphate, and of the glucuronides of testosterone and17ß-oestradiol, by urine of reproductively mature male and female rainbow trout(Oncorhynchus mykiss). Journal of Fish Biology, 44: 117-129.

A.P. Scott* and N.R. Liley

Journal of Fish Biology, 44: 117-129