[Placental growth hormone. Significance relative to growth hormone and lactogen hormone]

Abstract

Normal human placenta secretes within maternal compartment a pregnancy associated protein, placental growth hormone (PGH). This entity, agonist of pituitary GH, appears responsible for the elevated IGF I blood levels observed in the mother during pregnancy, while pituitary GH is no longer secreted. PGH could thus play a significant role in the anabolic processes of pregnancy. The biochemical mechanism responsible for PGH production is the expression of the GH-V gene at the placental level. This has been demonstrated by the positive probing of GH-V mRNA in this tissue, by the establishment of the restriction map and sequence of its cDNA as well as by the NH2-terminal sequence determination of both 22 and 25K PGH forms. The positive aspect of this function for human reproduction gains weight in that a placenta deleted for the CS-A, GH-V and CS-B gene expresses alternative genes coding for protein similar or related to pituitary GH or hPL, respectively.