Immune responses and hematological variables of cultured great sturgeon (Huso huso) subjected to 11-ketotestosterone implantation

Despite studies on the effect of androgens in female teleost fish, many aspects of androgen supplementation in female sturgeon gametogenesis remain elusive. The aim of the study was to investigate the immunological and physiological responses of 4-year-old previtellogenic great sturgeon (Huso huso) (body weight 5580±165 g) to 11-ketotestosterone (11-KT) implants. The fish were divided into two groups of 6 fish: 11-KT group, which received a single intraperitoneal implant of 2.5 mg 11-KT and a placebo group, which was implanted without 11-KT for 56 days. Just before implantation and on days 21 and 56 post-implantation, serum samples were taken to measure immune parameters (IgM, C3 and C4) and some related biochemical and hematological indices. Results showed a significant reduction in IgM concentrations after implantation in both the 11-KT and placebo groups (p<0.05). The concentration of C4 showed an opposite trend and significantly increased in both the placebo and 11-KT groups (p<0.05). The concentration of C3 and IgM to protein (IgM/p) ratio showed no significant differences during the experiment (p>0.05). Serum testosterone (T) levels in the 11-KT implanted group increased significantly on days 21 and 56 post-implantation (p<0.01). The albumin to globulin ratio showed no significant change in the 11-KT group (p>0.05), but a significant difference was observed in the placebo group during the study period (p<0.05). In hematological parameters, the number of red blood cells significantly increased after 56 days compared with that after 21 days in both experimental groups (p<0.05), while white blood cells significantly increased in the 11-KT group after 56 days (p<0.05). The results indicated that implantation with or without 11-KT could suppress some immunity parameters of great sturgeon.