GH and IGF-I binding sites in adipose tissue, liver, skeletal muscle and ovaries of feed-restricted gilts

The influence of feed restriction on GH and IGF-I binding was examined in t he cyclic gilt. IGF-I, IGFBPs, insulin and leptin levels in plasma were als o measured. Twenty-four gilts whose oestrous cycle was synchronised were us ed. From day 3 to day 12, (with day 0 being the first day of oestrus) feed allowance was 240% and 80% of the energy requirements for maintenance for w ell-fed (H) and restricted gilts (L) respectively. Six gilts in each group were treated with an antagonist of GnRH but the treatment had no effect on any reported measurements. Blood and tissue samples were collected on days 12 and 13 respectively. L gilts lost live weight whereas H gilts gained wei ght. Plasma IGF-I, insulin and leptin concentrations were lower in L than i n H gilts whereas plasma IGFBP levels were not affected by feed restriction . The specific binding of I-125-bGH to adipose tissue, liver, skeletal musc le and ovary membranes did not differ significantly between H and L gilts. Specific binding of I-125-IGF-I to hepatic membranes was higher in L than i n H gilts whereas it did not differ between the two groups in the other tis sue membranes.