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Home / Equine Research Bank / J Anim Sci / Endocrine changes during the peripartal period related to co...
Journal of animal science2023; 101; doi: 10.1093/jas/skad146

Endocrine changes during the peripartal period related to colostrogenesis in mammalian species.

Abstract: This review discusses endocrine and functional changes during the transition from late gestation to lactation that are related to the production of colostrum in different mammalian species. Species covered in this article include ungulate species (cattle, sheep, goats, pigs, horses), rodents (rat, mouse), rabbits, and carnivores (cats, dogs), as well as humans. An immediate availability of high quality colostrum for the newborn after birth is crucial in species where a transfer of immunoglobulins (Ig) does not or only partially occur via the placenta during pregnancy. Declining activity of gestagens, in most species progesterone (P4), is crucial at the end of pregnancy to allow for the characteristic endocrine changes to initiate parturition and lactation, but the endocrine regulation of colostrogenesis is negligible. Both, the functional pathways and the timing of gestagen withdrawal differ considerably among mammalian species. In species with a sustaining corpus luteum throughout the entire pregnancy (cattle, goat, pig, cat, dog, rabbit, mouse, and rat), a prostaglandin F2α (PGF2α)-induced luteolysis shortly before parturition is assumed to be the key event to initiate parturition as well as lactogenesis. In species where the gestagen production is taken over by the placenta during the course of gestation (e.g., sheep, horse, and human), the reduction of gestagen activity is more complex, as PGF2α does not affect placental gestagen production. In sheep the steroid hormone synthesis is directed away from P4 towards estradiol-17β (E2) to achieve a low gestagen activity at high E2 concentrations. In humans the uterus becomes insensitive to P4, as parturition occurs despite still high P4 concentrations. However, lactogenesis is not completed as long as P4 concentration is high. Early colostrum and thus Ig intake for immune protection is not needed for the human newborn which allows a delayed onset of copious milk secretion for days until the placenta expulsion causes the P4 drop. Like humans, horses do not need low gestagen concentrations for successful parturition. However, newborn foals need immediate immune protection through Ig intake with colostrum. This requires the start of lactogenesis before parturition which is not fully clarified. The knowledge of the endocrine changes and related pathways to control the key events integrating the processes of colostrogenesis, parturition, and start of lactation are incomplete in many species. This manuscript reviews and compares hormonal and functional changes occurring in the conceptus (embryo and its extra-embryonic membranes) and their effects on the mammary gland during development from pregnancy to colostrum formation and milk production in multiple mammalian species. Declining activity of gestagens at the end of pregnancy is crucial to allow for both parturition and onset of milk production in most mammals. Strategies to achieve this state of low gestagen activity are different among species. In species where the corpus luteum is sustained throughout the entire pregnancy, luteolysis is the key event to initiate parturition and onset of milk secretion (cattle, goat, pig, cat, dog, rat, mouse, rabbit). However, in species where the placenta takes over gestagen production during the course of pregnancy, the achievement of a state of low gestagen activity is more complex. It ranges from redirection of the hormone production pathway away from gestagens in sheep, to decreasing sensitivity of the uterus towards gestagens in humans. In the horse, there is evidence pointing towards redirection of the hormone production as well as a decrease in sensitivity towards gestagens, but the exact mechanisms are still not clarified.
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Publication Date: 2023-05-09 PubMed ID: 37158662PubMed Central: PMC10237234DOI: 10.1093/jas/skad146Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research review examines the hormonal and functional changes across varying mammalian species that relate to the production of colostrum, the initial high-nutrient milk produced following birth. The species studied include ungulates (cattle, sheep, goats, pigs, horses), rodents (rats, mice), rabbits, carnivores (cats, dogs), and humans. It particularly focuses on a pattern of declining activity of progesterone towards the end of pregnancy, and how this process varies across species; colostrum production is pivotal for newborn survival where placental transfer of immunoglobulins does not occur or is partial.

Key Endocrine Changes during the Peripartal Period

The paper examines specific endocrine changes that occur towards the end of an animal’s pregnancy. This understanding is crucial for the management of parturition (the action of giving birth) and lactogenesis (the initiation of milk secretion) in diverse mammalian species:

  • The declining activity of gestagens, specifically progesterone, is found to be critical in late pregnancy to initiate both parturition and lactation across species.
  • However, the exact endocrine pathways and timing of gestagen withdrawal vary between different mammal types.
  • The research emphasizes that in certain species where a corpus luteum (a hormone-secreting body in the uterus) is sustained throughout the entire pregnancy, parturition and lactogenesis are initiated by prostaglandin-induced luteolysis (the degeneration of the corpus luteum).

Differences in Gestagens Activity Reduction

Another observation from the review revolves around the processes through which different species achieve reduced levels of gestagens during pregnancy:

  • The decline of gestagen activity at the end of pregnancy is a complex process in species where placental gestagen production takes over, compared to those with a sustained corpus luteum.
  • In sheep, there is a redirection of hormone production away from progesterone towards estradiol to achieve lower gestagen activity.
  • In humans and horses, the uterus eventually becomes insensitive to progesterone, leading to parturition despite high progesterone concentrations. However, lactogenesis is not completed until progesterone levels drop. In contrast to humans, horses need to begin lactogenesis before giving birth as horse newborns need immediate immunization via colostrum.

Implications of the Research

Understanding the endocrine changes and related pathways during pregnancy is essential as it allows researchers to control key events relating to colostrogenesis (formation of colostrum), parturition, and the start of lactation. This knowledge, however, remains incomplete in many species:

  • There is a call for further research to clarify the processes that induce lactogenesis prior to parturition in horses, for instance.
  • The research’s implications can also influence how neonatal intensive care is managed across species, particularly for those creatures where colostrum and immunoglobulin intake is critical for neonatal survival immediately after birth.

Cite This Article

APA
Bigler NA, Gross JJ, Baumrucker CR, Bruckmaier RM. (2023). Endocrine changes during the peripartal period related to colostrogenesis in mammalian species. J Anim Sci, 101. https://doi.org/10.1093/jas/skad146

Publication

Journal of animal science
ISSN: 1525-3163
NlmUniqueID: 8003002
Country: United States
Language: English
Volume: 101

Researcher Affiliations

Bigler, Naomi A
  • Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland.
Gross, Josef J
  • Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland.
Baumrucker, Craig R
  • Department of Animal Science, Penn State University, University Park, PA 16802, USA.
Bruckmaier, Rupert M
  • Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland.

MeSH Terms

  • Pregnancy
  • Female
  • Swine
  • Cattle
  • Humans
  • Rats
  • Horses
  • Animals
  • Rabbits
  • Sheep
  • Dogs
  • Mice
  • Progestins
  • Dinoprost
  • Placenta / metabolism
  • Parturition
  • Colostrum / metabolism
  • Progesterone / metabolism
  • Rodentia / metabolism

Conflict of Interest Statement

The authors have declared no conflict of interests.

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