Effect of 11-ketotestosterone on sperm production by male spotted wolffish (Anarhichas minor)

Abstract

Three experiments were performed during spring 2004, to develop a method to elevate the blood plasma level of 11-ketotestosterone (11-KT) in male brood stock of spotted wolffish Anarhichas minor, and to study the effects of 11-KT on sperm production. Intraperitoneal implantation of silastic capsules containing 11-KT - coconut butter mixture and 11-KT - sesame oil mixture and intramuscular injection of 11-KT – propylene glycol mixture were tested. Blood plasma 11-KT levels were quantified by radioimmunoassay. Low and medium doses (c. 0.09 mg/kg and c. 0.18 mg/kg) of 11- KT-coconut butter mixture administered in silastic capsules did not elevate the plasma 11-KT levels. High dose (c. 0.37 mg/kg) of 11-KT – coconut butter mixture gave an increase (6.48 ± 1.89ng/ml) of about 3 times pretreatment level (1.83 ± 0.36 ng/ml) for one week. 11-KT- sesame oil mixture (1 mg/kg dose) elevated the plasma 11-KT levels (22.58 ± 4.69 ng/ml) compared to the controls (14.98 ± 3.45 ng/ml) for one week. Silastic capsule implants did not maintain the elevation more than one week irrespective of dose or vehicle (coconut butter, sesame oil). Intramuscular injection of 11-KT dissolved in propylene glycol (1mg/kg) elevated plasma 11-KT (99.16 ± 56.04 ng/ml) to about 12 times the level of the controls (7.44 ± 2.04 ng/ml), and was identified as a more effective method than silastic capsule implantation. Sperm production was studied by examining milt volume, spermatocrit, milt pH and motility of sperm. 11-KT treatment with intramuscular injection significantly increased milt volume. Mean milt volumes in treatment and control groups were 14.26 ± 4.2 ml and 4.73 ± 2.8 ml respectively. 11-KT treatment had no significant effects on spermatocrit, which was very low (2 -4 %) in both treatment and control fish. Total sperm cell volume in milt was significantly high in treatment group. There were no significant differences in milt pH and sperm motility between 11-KT treatment and control groups. The results indicate that 11-KT induces the spermatogenesis but does not influence the motility of sperm.