Endocrine Abstracts

The hypoxia, associated to intra-uterine growth restriction, is related to high concentrations of IGFBP1 and unchanged concentrations of IGF1 in animals. Nevertheless, during threatening life events, low IGFI concentrations and high IGFBP1 concentrations was reported. Furthermore, severe hypoxia increased the IGF1R expression of the neuronal growth cones in the ovine fetal brain. No information is available regarding the regulation of the IGF system by the acute hypoxia in humans. The aim of this study was to evaluate the effect of acute hypoxia on the IGF system in children. Twenty seven previously health children (14 boys and 13 girls) aged 15 days to 9.5 years were studied in 2 different situations: during acute hypoxia due to acute respiratory distress and after full recovering. In these two opportunities oxygen saturation was accessed using pulse-oximeter and blood samples were collected for serum IGF1 and IGFBP1 determination and also for analyzing of IGF1R gene expression in peripheral lymphocytes. IGF1 and IGFBP1 were determined by specific ELISA. Lymphocytes were first isolated from other blood cells using Fycoll-Hypaque and then RNA was extracted. The levels of mRNA expression of the IGF1R gene were analyzed by quantitative real-time PCR. Data were pared-compared by Wilcoxon non-parametric test. Oxygen saturation was 87.8±3.5% in the fist evaluation (Hypoxic state or HS) and 96.4±1.2% after recovering (non-HS) (P<0.0001). IGF1 levels were lower during HS compared to non-HS (median: 12 vs. 56 ng/ml) (P<0.0001) whilst IGFBP1 were higher during HS than in non-HS (median: 113 vs. 60 ng/ml) (P=0.004). The expression of IGF1R mRNA, expressed as 2-ΔΔCT, were higher during HS than after it (1.28 vs 0.93) (P=0.03). In conclusion, the above results showed during acute hypoxia a combination of alterations usually associated with decrease of IGF action. The higher expression of IGF1R mRNA may reflect an up regulation of the transcriptional process.