Human placental growth hormone

Area of Science:

• Endocrinology
• Reproductive Biology
• Molecular Genetics

Background:

• Placental growth hormone (PGH) is a unique variant of growth hormone, encoded by the GH-V gene and exclusively expressed in the human placenta.
• PGH differs from pituitary growth hormone (PGH) by 13 amino acids, exhibiting distinct somatogenic and lactogenic activities.

Purpose of the Study:

• To elucidate the role and secretion patterns of placental growth hormone (PGH) during human gestation.
• To investigate the implications of PGH secretion on maternal physiology, particularly insulin-like growth factor-I (IGF-I) levels and its association with intrauterine growth restriction (IUGR).

Main Methods:

• Utilized specific monoclonal antibody assays to quantify PGH and pituitary GH in maternal circulation.
• Conducted in vitro and in vivo studies to assess the effects of glucose on PGH secretion.
• Measured PGH levels in pregnancies complicated by intrauterine growth restriction.

Main Results:

• PGH gradually replaces pituitary GH in maternal circulation from mid-gestation onwards.
• PGH is secreted continuously by the placenta, influencing maternal IGF-I levels.
• PGH secretion is inhibited by glucose and reduced in pregnancies with IUGR.
• PGH is not detectable in fetal circulation, suggesting no direct fetal growth impact.

Conclusions:

• Placental growth hormone (PGH) is a key endocrine factor during pregnancy, regulating maternal adaptations.
• PGH's role in controlling maternal IGF-I and its altered levels in IUGR highlight its importance in pregnancy outcomes.
• Further research may explore PGH's autocrine/paracrine functions in placental development via growth hormone receptors.