Effects of 11-Ketotestosterone on Development of the Previtellogenic Ovary in the Sterlet, Acipenser ruthenus

Abstract

11-ketotestosterone (11-KT) is a non-aromatizable and the most potent androgen in a few teleost. It has been reported that 11-KT in serum had a high concentration and increased sharply before the period of yolk deposition in females of few fishes. The aim of this study was to analyze the role of 11-KT both <i>in vivo</i> and <i>in vitro</i> on ovarian development, related gene expression levels, Vitellogenin (Vtg) synthesis, and serum sex steroid concentrations in previtellogenic cultured sterlet (<i>Acipenser ruthenus</i>). Silastic strips embedded with 11-KT (5 or 25 mg/kg) were implanted <i>in vivo</i> for 30 days. Ovarian masculinization or sex reversal was not observed. Histological analysis showed that 11-KT promoted sterlet ovarian development in a dose-dependent manner. Vtg and testosterone (T) increased significantly, while 17β-estradiol (E2) decreased with no significant difference among groups. The expression of genes androgen receptor (<i>ar</i>), <i>vtg</i> and lipoprotein lipase (<i>lpl</i>) were significantly increased in liver. However, 11-KT had no effect on the expression of <i>foxl2</i> and <i>cyp19a1</i> in ovary. <i>In vitro</i>, after incubation with 11-KT (10 and 100 μM) for 5 days, both T and E2 concentrations increased in both hepatic explants and ovarian explants culture medium; the concentration of Vtg also increased in hepatic explants culture medium. The expression of <i>ar, era, vtg</i>, and <i>lpl</i> increased significantly in hepatic explants. However, only the expression of <i>era</i> significantly increased in cultured ovarian explants. Altogether, these results suggest that 11-KT induced ovarian development, as well as Vtg and lipid synthesis, and could be an important factor facilitating the initiation of Vtg synthesis in the liver of the previtellogenic sterlet.