Effects of castration and cyproterone acetate on some biochemical constituents of the seminal vesicle and/or testis in the catfish Heteropneustes fossilis (bloch)

Castration of the catfish Heteropneustes fossilis for different duration (u p to 4 weeks) in the preparatory-prespawning phase resulted in varied effec ts on plasma testosterone and seminal vesicle (SV) biochemical parameters i n a duration-dependent manner. Although plasma testosterone was significant ly reduced at all duration of castration in comparison to sham control valu es, a duration-dependent increase was noticed in the castrates after week 1 . SV-somatic index (SVSI) increased significantly and steadily during castr ation except in week 1. Concentrations of total proteins decreased initiall y in week 1, and increased subsequently to the sham control level in week 2 and significantly above the sham control values in weeks 3 and 4. Hexosami ne concentration was significantly low in weeks 1 and 2, and was restored i n weeks 3 and 4. Fructose concentration decreased significantly in weeks 1, 2 and 3, and increased significantly in week 4. In contrast, glucose conce ntration increased significantly in week 1, restored to control levels in w eeks 2 and 3, and decreased significantly in week 4. Cyproterone acetate (C A) treatment in a dose of 1 mg/fish/day for 21 days in castrated fish cause d significant reductions in plasma testosterone and SVSI in weeks 2 and 3, and in the concentrations of total protein, hexosamines and fructose in wee ks 1, 2 and 3. The glucose concentration, on the other hand, registered a p rogressive increase, which was significantly higher in weeks 2 and 3. In sh am castrated (testis intact) fish, similar changes were noticed but with si gnificant decrease of plasma testosterone and increase of SV glucose even i n week 1. In the testis of sham castrated fish, similar changes were notice d in gonado-somatic index and other biochemical correlates. From the result s, it is suggested that the stimulatory (hypersecretory) effect of castrati on on the SV can be attributed to local production of testosterone. The CA treatment could block or reverse the effects in castrates suggesting androg en involvement in the stimulatory effect.