A comparison of steroid profiles in the testis and seminal vesicle of the catfish (Heteropneustes fossilis).

In the present study, distribution of steroid hormones (estradiol-17β (E), testosterone (T), corticosteroids and progestins) in the testis and seminal vesicles (SV) of the catfish Heteropneustes fossilis were investigated in two seasons (pre-spawning and spawning phases) of the reproductive cycle. The data showed that the levels of the steroid hormones varied significantly in both reproductive phases and exhibited organ-related differences. Sex steroid levels were highest in the pre-spawning phase and lowest in the spawning phase. The concentration of E and cortisol was highest in the testis. However, E level was higher in the SV compared to the testis in the pre-spawning phase and during spawning phase there was no significant difference in the E level of testis and SV. Seminal vesicle and testis recorded higher levels of cortisol in the spawning phase. The concentration of corticosterone was significantly higher in testis during pre-spawning phase and in seminal vesicle during the spawning phase. 21-deoxycortisol was higher in the pre-spawning phase in the SV but not in the testis and deoxycorticosterone was significantly higher in the pre-spawning phase than spawning phase. Progesterone was high in the pre-spawning phase and low in all tissues in the spawning phase. 17-P concentration was the highest in both SV and testis during spawning phase. In the testis 17, 20β-DP concentration was the highest in the pre-spawning phase. In contrast, in the SV, 17, 20β-DP was lowest during pre-spawning phase. This study shows high levels of corticosteroid profile in the testis and SV. The physiological significance of the steroids other than T is not clear at present. However, knowledge of seasonal profile of key steroid hormones in the male catfish may be helpful in monitoring reproductive capability and important for fish breeding in captivity.