A. Rahdari - Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Guilan, Iran
M.R. Khoshkholgh - Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Guilan, Iran
M. Yarmohammadi - International Sturgeon Research Institute, Agricultural Research Education and Extension Organization (AREEO), Rasht, Iran
M. Ortiz-Zarragoitia - Department of Zoology and Animal Cell Biology, Faculty of Science and Technology, and Plentzia Marine Station, University of the Basque Country (UPV/EHU), Bilbao, Basque Country, Spain
B. Falahatkar - Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Guilan, Iran

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 ۴-year-old previtellogenic great sturgeon (Huso huso) (body weight ۵۵۸۰±۱۶۵ g) to ۱۱-ketotestosterone (۱۱-KT) implants. The fish were divided into two groups of ۶ fish: ۱۱-KT group, which received a single intraperitoneal implant of ۲.۵ mg ۱۱-KT and a placebo group, which was implanted without ۱۱-KT for ۵۶ days. Just before implantation and on days ۲۱ and ۵۶ post-implantation, serum samples were taken to measure immune parameters (IgM, C۳ and C۴) and some related biochemical and hematological indices. Results showed a significant reduction in IgM concentrations after implantation in both the ۱۱-KT and placebo groups (p<۰.۰۵). The concentration of C۴ showed an opposite trend and significantly increased in both the placebo and ۱۱-KT groups (p<۰.۰۵). The concentration of C۳ and IgM to protein (IgM/p) ratio showed no significant differences during the experiment (p>۰.۰۵). Serum testosterone (T) levels in the ۱۱-KT implanted group increased significantly on days ۲۱ and ۵۶ post-implantation (p<۰.۰۱). The albumin to globulin ratio showed no significant change in the ۱۱-KT group (p>۰.۰۵), but a significant difference was observed in the placebo group during the study period (p<۰.۰۵). In hematological parameters, the number of red blood cells significantly increased after ۵۶ days compared with that after ۲۱ days in both experimental groups (p<۰.۰۵), while white blood cells significantly increased in the ۱۱-KT group after ۵۶ days (p<۰.۰۵). The results indicated that implantation with or without ۱۱-KT could suppress some immunity parameters of great sturgeon.

۱۱-ketotestosterone, Immunity, Beluga sturgeon.