DECREASED EXPRESSION OF PLACENTAL GROWTH-HORMONE IN INTRAUTERINE GROWTH-RETARDATION

During normal pregnancy, the levels of placental GH in the maternal ci rculation increase significantly until 35 wk of gestation. We have pre viously shown that these levels are significantly reduced in cases of intrauterine growth retardation (IUGR). To better understand the basis of this observation, we have studied the expression of placental GH i n placentas from normal births (n = 6) and births with IUGR (n = 5). I n situ hybridization histochemistry was used to determine the mean num ber of cells per area expressing this message, as well as the mean lev el of specific mRNA per cell, We have found that the mean mRNA signal level per cell of placental GH did nor differ between normal or IUGR p lacentas. However, the mean number of cells/area expressing this mRNA was significantly greater in normal placentas compared with IUGR place ntas (normal 12.8 +/- 0.9 cells/unit area, IUGR 4.9 +/- 2.4 cells/unit area, analysis of variance: p < 0.004). These data suggest that the d ecreased levels of placental GH in the maternal circulation in IUGR ar e not due only to the reduced size of the placenta, but also to change s in the placental tissue which result in a reduced number of cells pe r area that are capable of producing this peptide.