Administration of insulin-like growth factor-I, but not growth hormone, increases maternal weight gain in late pregnancy without affecting fetal or placental growth

Publisher Website
Google Scholar
Abstract
During late pregnancy in the rat, circulating levels of insulin-like growth factor-I (IGF-I) and some IGF-binding proteins (IGFBP) decline. The aim of the present study was to determine the relationship of GH to circulating IGF and IGFBP in the late-pregnant rat and to examine the effects on maternal, fetal and placental growth of preventing the decline in serum IGF and IGFBP concentrations. During the first 9 days of pregnancy, IGF-I concentrations increased from 340 to 500 μg/l. Recombinant human (rh) GH at 2·4 mg/kg per day and rhIGF-I at 1·4 mg/kg per day were infused into pregnant rats via osmotic mini pumps during the second half of pregnancy. After pump implantation on day 11 of pregnancy, only IGF-I infusion significantly increased circulating IGF-I. A maximum IGF-I concentration of 907 μg/l was measured on day 14 during treatment with IGF-I, after which the serum concentration decreased to 510 μg/l by day 20 of pregnancy. The serum IGFBPs were examined using a Western ligand blot technique. Infusion of neither GH nor IGF-I returned the IGFBPs to non-pregnant levels. Administration of IGF-I slightly increased IGFBP-3 and a smaller 32 kDa IGFBP at days 17 and 20 of pregnancy. Neither fetal nor placental weight was significantly different between treatment groups. However, administration of IGF-I significantly increased maternal weight gain during the 10-day treatment period. Thus, pregnant rats infused with IGF-I gained 99±4 g (mean ± s.e.m., n = 10) compared with rats treated with GH or vehicle which gained 72±4 g (n = 9) and 77±4 g (n = 10) respectively. The increase in maternal weight after administration of IGF-I was not due to increased litter size, fetal or placental weight. The increased maternal weight gain after IGF administration, without affecting fetal and placental weights, suggests a modification in the mode of maternal nutrient repartitioning during late pregnancy. Journal of Endocrinology (1991) 130, 395–400

This publication has 0 references indexed in Scilit: