EPIDERMAL GROWTH-FACTOR AND INSULIN-LIKE GROWTH-FACTOR-I DIFFERENTLY INFLUENCE THE DIRECTIONAL ACCUMULATION AND TRANSFER OF 2-AMINOISOBUTYRATE (AIB) BY HUMAN PLACENTAL TROPHOBLAST IN 2-SIDED CULTURE

We examined the effects of epidermal growth factor (EGF) and insulin-l ike growth factor I (IGF-I) on the uptake of AIB by and its transfer a cross near-term human placental syncytiotrophoblast in two-sided cultu re. Pre-incubation of the trophoblast cell layer with either EGF (50ng /ml) or IGF-I (100ng/ml) on the apical (microvillous, in vivo maternal -facing) side reduced rates of unidirectional microvillous-to-basa1 tr anstrophoblast AIB transfer, increasing AIB retention within the cells . EGF on the basal (fetal-facing) side of the cell layer enhanced AIB uptake from the microvillous side but also increased overall mediated permeability in both directions. IGF-I at the basal surface, however, increased AIB uptake across the microvillous membrane, and induced a b ackflux from the cells into the basal medium dependent upon basal AIB concentration, suggesting that in vivo IGF-I on the fetal side enhance s maternal-to-fetal placental transfer. The ideas are consistent with current concepts of maternal-placental and fetal-placental interaction s regulating pregnancy and fetal development. (C) 1994 Academic Press, Inc.