A SOMATOSTATIN ANALOG DECREASES EMBRYONIC LOSS FOLLOWING SUPEROVULATION IN RATS BY NORMALIZING INSULIN-LIKE GROWTH-FACTOR-I ACTION IN THE UTERUS

This study was designed to determine whether the somatostatin analogue , octreotide, could prevent embryonic loss by normalizing increased ut erine insulin-like growth factor-I (IGF-I) action related to hyperoest rogenaemia following superovulation, Superovulated immature and oestra diol-17 beta-treated adult rats were infused with 100 or 300 mu g/ml o f octreotide respectively, or injected daily with 1 or 10 mu g of octr eotide from day 1 to day 3 of pregnancy. On day 3, embryos were collec ted from the oviducts and uteri, Uterine luminal fluid was subjected t o embryo culture, The amounts of uterine IGF-I and IGF binding protein s (IGFBP) were determined by radioimmunoassay and ligand binding assay respectively, Octreotide infusion normalized uterine IGF-I action fol lowing superovulatory and oestradiol-17 beta treatment, by reducing IG F-I concentrations and increasing IGFBP concentrations, Octreotide inf usion increased the number of normal embryos by 2.7-fold and 1.7-fold in superovulated and oestradiol-17 beta-treated rats respectively, and reversed the detrimental effects of uterine luminal fluid on embryoni c development caused by superovulatory and oestradiol-17 beta treatmen t, Daily injections with octreotide had similar but reduced effects in all parameters examined in both treatment groups, In conclusion, octr eotide may reduce embryonic loss, at least in part, by normalizing IGF -I action following superovulation.