In vitro experiments were conducted

In vitro experiments were conducted to examine the role of hCG (100 ng/mL), b-insulin (0.8 IU/ mL) and human IGF-I (25 nM) on steroidogenesis and oocyte maturation of the grey mullet. Pilot experiments were conducted in vitro to determine the effective doses of hCG, IGF-I and b-insulin with duration of treatments for 9h, 12h and 15h. The results showed maximum effects on oocyte maturation, evaluated by GVBD% in the mullet ovary (13). To determine the signaling molecule for steroidogenesis and oocyte maturation, specific inhibitors such as actinomycin D (0.5 µg/ mL) for transcription, cycloheximide (0.5 µg/mL) for translation, trilostane (0.5 µg/ mL) for 3β-hydroxysteroid dehydrogenase, and Wortmannin (8 µM) for PI3 kinase were used. In addition to steroid synthesis inhibitor, gap junction inhibitors, 1-octanol (0.5 nM) and 1-heptanol (0.5 nM), were used for in vitro study of 17,20β-DP, testosterone and E2 profiles. Incubation time of each experiment was 15 h.