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The sex steroid hormone progesterone is essential for normal development and maturation of the endometrium in preparation for the embryo implantation and the maintenance of pregnancy. Insulin-like growth factor (IGF) system that is composed of IGF-I, IFG-II, IGF binding proteins (IGFBPs) is also involved in the maintenance of pregnancy. In addition, liver, kidney, and uterus is a target tissue for IGF system. However, the effect of exogenous progesterone on IGF system was not elucidated in female rats. Therefore, we investigated the effect of progesterone on insulin-like growth factors (IGFs) and IGF-binding proteins is serum, liver, kidney, and uterus in female ovariectomized rats. IGFs concentration was measured by radioimmuoassay (RIA) and IGFBPs levels by western ligand blotting(WLB). IGF-I concentration was increased in serum, liverm and uterus, but not in kidney of progesterone-treated ovariectomized rats, compared to control (P<0.05). IGF-II concentration was decreased in liver, but not in serum, kidney, and uterus of progesterone-treated rats, compared to control (P<0.05). IGFBP-3 was increased in serum, but not in liver of progesterone-treated rats, compared to control. IGFBP-2 was decreased in kidney, but not in others tissues of progesterone-treated rats, compared to control. These results suggest that progesterone may exert diverse physiological functions via the tissue-specific regulation of IGFs/IGFBPs system in female rats.
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