A somatostatin analogue 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 uterineinsulin-like growth factor-I (IGF-I) action related to hyperoestrogenaemiafollowing superovulation. Superovulated immature andoestradiol-17beta-treated adult rats were infused with 100 or 300 microg/mlof octreotide respectively, or injected daily with 1 or 10 microg ofoctreotide from day 1 to day 3 of pregnancy. On day 3, embryos werecollected from the oviducts and uteri. Uterine luminal fluid was subjectedto embryo culture. The amounts of uterine IGF-I and IGF binding proteins(IGFBP) were determined by radioimmunoassay and ligand binding assayrespectively. Octreotide infusion normalized uterine IGF-I action followingsuperovulatory and oestradiol-17beta treatment, by reducing IGF-Iconcentrations and increasing IGFBP concentrations. Octreotide infusionincreased the number of normal embryos by 2.7-fold and 1.7-fold insuperovulated and oestradiol-17beta- treated rats respectively, andreversed the detrimental effects of uterine luminal fluid on embryonicdevelopment caused by superovulatory and oestradiol-17beta treatment. Dailyinjections with octreotide had similar but reduced effects in allparameters examined in both treatment groups. In conclusion, octreotide mayreduce embryonic loss, at least in part, by normalizing IGF-I actionfollowing superovulation.