Release of sex steroids into the water by roach

Electro-olfactogram (EOG) recordings of the olfactory epithelium of both male and female roach Rutilus rutilus demonstrated that both sexes were able to detect free and glucuronidated 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) with high sensitivity. Male, but not female, roach were also sensitive to androstenedione. Sexually mature female roach were shown to release free 17,20beta-P, glucuronidated 17,20beta-P and androstenedione into the water; for all three steroids, the rate of release was significantly enhanced by injection of carp pituitary extract (CPE). A series of trials was also carried out which showed that mature mates, and to a lesser extent immature males and females, were able also to release free and glucuronidated 17,20beta-P, both before and after CPE treatment. Water extracts from containers that had held CPE-treated mature male and female roach were examined for the presence of other steroids. This revealed that free and glucuronidated 17,20beta-P plus free and glucuronidated 17,20beta,21-trihydroxy-4-pregnen-3 -one (17,20beta, 21-P) predominated in water extracts from both sexes. The free moieties of 17,20alpha-dihydroxy-4-oregnen-3-one, 17-hydroxyprogesterone and 11-deoxycortisol were found at concentrations which were-between four and 20 times lower than those of free 17,20beta-P. Androstenedione was found at concentrations which were 25-fold lower than those of 17,20beta-P. Despite its apparent high rate of release by sexually mature male and female roach, free 17,20beta,21-P was found not to exhibit any EOG activity at the highest dose tested (10(-7) M). (C) 2004 The Fisheries Society of the British Isles.