Consequences of the presence of the Booroola F gene on the intraovarian insulin-like growth factor system and terminal follicular maturation in Mérinos d'Arles ewes.

Abstract In sheep, the presence of the Booroola F gene has several important consequences for ovarian function. This study investigated the consequences of the presence of the F gene for the insulin-like growth factor (IGF) system in the ewe ovary. Studies were undertaken in ovaries from F+ and ++ Merinos d'Arles ewes to determine 1) the levels of type I IGF receptors and IGF binding proteins (IGFBPs) in follicular cells by quantitative autoradiography of [125]-IGF-I binding sites on ovarian sections; 2) the pattern of intrafollicular IGFBPs, by Western-ligand blotting on follicular fluids; and 3) the effects of IGF-I and FSH on proliferation and differentiation of granulosa cells in vitro, assessed by progesterone secretion and cytochrome P450 side-chain cleavage (P450scc) expression. The amounts of type I IGF receptors were similar in F+ and ++ follicular cells; however, at the same follicular size, F+ healthy follicles contained lower concentrations of IGFBPs smaller than 40 kDa (particularly IGFBP-2) ...