Insulin-like growth factors in sheep uterine fluids: concentrations and relationship to ovine trophoblast protein-1 production during early pregnancy.

Uterine luminal fluids (ULFs) from Days 10, 12, 14, and 16 cyclic (C) and pregnant (Px) ewes were analyzed for presence of insulin-like growth factors (IGF-I, IGF-II) and other mitogenic factor(s). IGF content and non-IGF mitogenic activity were measured by IGF RIAs after removal of IGF binding proteins and by stimulatory effects on DNA synthesis of density arrested AKR-2B cells, respectively. ULF IGF-I content was not different between days, but differences in IGF-I between C and Px groups at Day 16 (C greater than Px) were found (p less than 0.05). ULF IGF-II content was not different between C and Px ewes; however, differences among days (p less than 0.01) were apparent. In both C and Px ewes, Day 14 ULF had highest IGF-II content (C: 4.60 +/- 0.98 ng/ml, Px: 5.39 +/- 1.38 ng/ml). In Day 12 and Day 14 (C and Px) ULF, IGF-II concentration was about 10-fold greater than that of IGF-I. AKR-2B mitogenic activity in ULF differed among days (p less than 0.01), but not between C and Px ewes. Highest activity was observed for Day 14 and Px ULF, whereas lowest activity was for Day 10 C and Day 16 Px ULF. Sephadex G-200 gel-filtration chromatography of ULF from Day 14 Px ewes demonstrated mitogenic activity in the column void volume fractions and in the 30-kDa size range of eluted proteins. Day 13 conceptuses were cultured in serum-free medium to define the effect of exogenous IGFs on ovine trophoblast protein-1 (oTP-1) secretion.(ABSTRACT TRUNCATED AT 250 WORDS)