Endocrine regulation and extended follow up of longitudinal growth in intrauterine growth-retarded rats

Bilateral uterine artery ligation in late gestation was performed in pregna nt darns in order to determine the effects of intrauterine growth retardati on (IUGR) on long-term postnatal somatic growth and the GH neuroendocrine a xis in the adult female and male rat. Body weight (BW), nose-anus length (N AL) and tail length (TL) were recorded at regular intervals in both the IUG R and control (CON) offspring until the age of 93 days. Spontaneous 6-h GH secretory profiles and serum IGF-1 were determined around the age of 100 da ys in both the IUGR and the CON group. No catch-up growth in BW, NAL or TL was observed in young adult male IUGR rats. Female IUGR rats did catch up i n NAL beyond the age of 57 days and in TL before weaning, but did not catch up at any time in BW. Spontaneous 6-h CH secretory profiles in female and male IUGR rats at a mean age of 100 +/- 4 days were similar to their contro ls at a mean age of 101 +/- 4 days. Overall median 6-h rat GH plasma concen trations, rat GH peak amplitude, number of rat GH peaks and sum of peak are a were not significantly diffterent. Median serum IGF-1 levels in young adu lt female and male IUGR rats showed no difference compared with their respe ctive controls. These results demonstrate that IUGR, after bilateral uterin e artery ligation in late gestation, leads to incomplete BW catch-up growth in young adult rats of both sexes with physiological GH/IGF-1 secretion, s uggesting intrauterine modulation of tissue responsiveness to GH and IGF-1. Female IUGR rats do catch up in NAL and TL, developing disturbed body prop ortions.