Catch-up growth in intrauterine growth retarded rats: its correlation with histomorphometric changes of the pituitary somatotrope cells

SUMMARY The aim of the present study was to examine the long-term effects of prenatal injure on body and craniofacial growth in intrauterine growth retarded (IUGR) animals and its correlation with histomorphometric changes of the pituitary somatotrope population. IUGR model was carried out by means of uterine vessels ligation in pregnant rats at 14 th day of pregnancy. Control and sham-operated animals were also included. The animals were Xrayed at 1, 21, and 84 days of age. Body weight, neural and facial variables were measured. Pituitaries were processed for light microscopy and immunolabeled with antiGH sera. Morphometry was performed by means of an image-analysis system. Data were processed by ANOVA, and Wilcoxon tests. Body weight was significantly lower in newborn IUGR rats compared with that of their control counterparts, even during postnatal growth. Both neurocranium and face were similarly affected at birth and weaning. At 84 days of age, despite facial growth exhibited a partial recovery, cranial volumes remained smaller in IUGR animals. Quantitative immunohistochemistry revealed a significant decrease in the volume and cell densities in IUGR compared to control age peers. Adequate nutritional and environmental conditions were insufficient to reverse the effects of a reduced uteroplacental blood supply on fetal growth. The timing and duration of the growth insult seem to be crucial for the occurrence of catch-up body weight and cranial growth in the rat. The lack of complete catchup in these IUGR animals may be associated to an alteration in the GH production.