Detection of placental growth hormone variant and chorionic somatomammotropin-L RNA expression in normal and diabetic pregnancy by reverse transcriptase-polymerase chain reaction

Diabetes is a common complication encountered during pregnancy. Earlier stu dies indicated that diabetic placentas bear morphological alterations consi stent with modified placental differentiation, including alterations in the villous cellular content, structure, and total surface. Limited data assoc iating the diabetic status with the expression of terminal placental differ entiation markers are available. The human growth hormone/chorionic somatom anamotropin (hGH/CS) family consists of five genes, one of which (GH-N) is expressed efficiently in pituitary while the other four (CS-A, B, L, and hG H-V) are expressed in placenta and represent ultimate placental differentia tion markers. We developed and applied a sensitive RT-PCR method coupled wi th diagnostic restriction digestion to determine the relative levels of the hGH/CS family in normal pregnancies and examine whether their mRNA express ion pattern is altered in pregnancies complicated by diabetes. We show that relative hCS-L content changes during placental development. Specifically, normal term placentas express higher relative levels of hCS-L, lower relat ive hGH-V levels and a 70-fold lower hGH-V/CS-L mRNA ratio compared to earl y placentas. Also, many term placentas from diabetic pregnancies express lo wer relative levels of hCS-L mRNA and a much higher hGH-V/CS-L mRNA ratio c ompared to normal term placenta, resembling more an early placenta pattern of expression. Thus, our study suggests that the expression of terminal pla cental differentiation markers, such as the hGH/CS genes, is altered in ter m placentas from these diabetics reflecting either impaired placental diffe rentiation or post-differentiation impairment of normal placental function. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.