Effects of Castration and Cyproterone Acetate On Some Biochemical Constituents of the Seminal Vesicle and/or Testis in the Catfish Heteropneustes Fossilis (Bloch)

Abstract

Castration of the catfish Heteropneustes fossilis for different duration (up to 4 weeks) in the preparatory-prespawning phase resulted in varied effects on plasma testosterone and seminal vesicle (SV) biochemical parameters in a duration-dependent manner. Although plasma testosterone was significantly reduced at all duration of castration in comparison to sham control values, a duration-dependent increase was noticed in the castrates after week 1. SV-somatic index (SVSI) increased significantly and steadily during castration except in week 1. Concentrations of total proteins decreased initially 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. Hexosamine concentration was significantly low in weeks 1 and 2, and was restored in weeks 3 and 4. Fructose concentration decreased significantly in weeks 1, 2 and 3, and increased significantly in week 4. In contrast, glucose concentration increased significantly in week 1, restored to control levels in weeks 2 and 3, and decreased significantly in week 4. Cyproterone acetate (CA) treatment in a dose of I mg/fish/day for 21 days in castrated fish caused significant reductions in plasma testosterone and SVSI in weeks 2 and 3, and in the concentrations of total protein, hexosamines and fructose in weeks 1, 2 and 3. The glucose concentration, on the other hand, registered a progressive increase, which was significantly higher in weeks 2 and 3. In sham castrated (testis intact) fish, similar changes were noticed but with significant decrease of plasma testosterone and increase of SV glucose even in week 1. In the testis of sham castrated fish, similar changes were noticed in gonado-somatic index and other biochemical correlates. From the results, it is suggested that the stimulatory (hypersecretory) effect of castration on the SV can be attributed to local production of testosterone. The CA treatment could block or reverse the effects in castrates suggesting androgen involvement in the stimulatory effect.