Corticotropin-releasing hormone-binding protein in primates

Area of Science:

• Reproductive biology
• Endocrinology
• Primate physiology

Background:

• Placental corticotropin-releasing hormone (CRH) influences human gestational length.
• A decline in CRH-binding protein (CRH-BP) in late human gestation is linked to parturition.
• CRH-BP has only been described in human circulation, and placental CRH mRNA is primate-specific.

Purpose of the Study:

• To investigate the presence of circulating CRH-BP in various primate species.
• To measure maternal and fetal CRH plasma concentrations in selected primates.
• To assess the potential role of CRH and CRH-BP in primate parturition and pregnancy.

Main Methods:

• Plasma samples from pregnant marmosets, lemurs, and rhesus monkeys (maternal and fetal) were analyzed.
• Gel chromatography was used to detect CRH-BP in plasma.
• CRH plasma concentrations were measured using radioimmunoassay techniques.

Main Results:

• CRH-BP was detected in apes (gorilla, chimpanzee, orangutan, gibbon), macaques, squirrel monkeys, and marmosets.
• CRH-BP was absent in mandrills, spider monkeys, and lemurs.
• Elevated maternal plasma CRH was found in pregnant marmosets and rhesus monkeys; fetal CRH was lower than maternal CRH in rhesus monkeys. CRH was undetectable in lemurs.

Conclusions:

• Circulating CRH-BP is conserved in apes but its presence varies among Old and New World monkeys and is absent in lemurs.
• The variable distribution of CRH-BP across primates does not support its role in the mechanism of parturition.
• Elevated maternal CRH in pregnant marmosets and rhesus monkeys suggests a potential role in their pregnancy.