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Ruminant placental lactogens: structure and biology
J C Byatt1, W C Warren, P J Eppard
1Animal Sciences Division, Monsanto Company, St. Louis, MO 63198.
Journal of Animal Science
|September 1, 1992
Summary
Ruminant placental lactogens (PL) are crucial hormones in pregnancy, influencing fetal growth and maternal metabolism. Their exact biological roles in cows, sheep, and goats require further investigation.
Area of Science:
- Reproductive biology
- Endocrinology
- Comparative physiology
Background:
- Ruminant placental lactogens (PL) belong to the somatotropin, prolactin gene family.
- Synthesized by trophectodermal binucleate cells, PL structure resembles prolactin but binds to somatotropin and prolactin receptors.
- Studied in cows, sheep, and goats, PL exhibits variations in molecular weight and maternal circulation concentrations.
Purpose of the Study:
- To review the structure, biology, and known functions of ruminant placental lactogens.
- To highlight the differences in PL characteristics and concentrations across ruminant species.
- To identify gaps in knowledge regarding the precise biological functions of PL in ruminants.
Main Methods:
- Literature review and synthesis of existing research on ruminant PL.
- Comparative analysis of PL structure, molecular weight, and secretion patterns.
- Examination of reported biological activities and potential roles in pregnancy.
Main Results:
- Ruminant PL show greater structural similarity to prolactin than somatotropin.
- Bovine PL is larger due to glycosylation compared to ovine and caprine PL.
- Maternal PL concentrations are significantly higher in sheep and goats than in cows, peaking in late gestation.
Conclusions:
- Ruminant PL possess both lactogenic and somatogenic activities, potentially with unique functions.
- PL may play roles in mammogenesis, fetal growth regulation, and maternal intermediary metabolism.
- The precise biological functions of ruminant PL remain to be fully elucidated.