Castration-induced hyperactivity of seminal vesicle in the catfish Clariasbatrachus: A case of paradox and blockade by antiandrogen (cyproterone acetate) treatment

Castration of the catfish Clarias batrachus in late preparatory-early presp awning phase (April-May) caused time-dependent stimulatory effect on morpho logy, weight, and in the concentrations of biochemical correlates, such as total proteins, fructose, hexosamines and sialic acid in the seminal vesicl e (SV). The peak changes were noticed on week 4 of castration. The hyperact ivity was related to augmented production of testosterone by the SV of cast rates with the levels significantly high from week 3 onwards. As a result, serum testosterone level fluctuated with a significant decrease in the firs t and fifth weeks, a significant increase in the third week, and no signifi cant difference in the second and fourth weeks. Serum E, level decreased si gnificantly throughout. Cyproterone acetate treatment (CA; 1 mg/fish daily for 21 days) from the second day of castration decreased the size and weigh t of the SV and the concentrations of total proteins, hexosamines, fructose and sialic acid. The antiandrogen treatment did not alter serum testostero ne level but the E, level was significantly decreased. It is concluded that the hypersecretory activity of the SV in castrates is a sequel to local sy nthesis and action of testosterone and the effect could be prevented by CA by blocking androgen actions.