Location: Forage-animal Production ResearchTitle: Prolactin genomics and biology in herbivores) Author
Submitted to: International Symposium on Fungal Endophytes of Grasses
Publication Type: Proceedings
Publication Acceptance Date: 3/14/2012
Publication Date: N/A
Citation: N/A Interpretive Summary: Prolactin was named because of its original biological function, promoting lactation; however, in recent years the biological functions of prolactin and its family of proteins exceeds 300 (Bole-Feysot et al., 1998). A chapter was written for the Proceedings of the 6th International Symposium on Fungal Endophytes of Grasses that covered all of the purported functions of prolactin, but also discussed evidence for its bio-modulator or “direct” effects versus its bio-marker or “indirect” effects on herbivore biology. Prolactin originally was described as solely affecting lactogeneis; however, prolactin has demonstrated that it has effects on other facets of animal biology. The chapter has reviewed some of the biological functions associated with prolactin, and attempted to assess those functions as bio-marker or bio-modulator. In total, prolactin impacts animal growth and development through a complicated series of interwoven physiological mechanisms. Consequently, the decreased prolactin concentrations associated with “fescue toxicosis” are both a bio-marker (dopamine agonist effects) and a bio-modulator (impaired vascular and immune function). This information will be useful to scientists working in the areas of endocrinology and animal growth and development.
Technical Abstract: Circulating prolactin concentrations are typically reduced in animals suffering from tall fescue toxicosis, and have become a standard biological marker for tall fescue toxicosis. Wild-type endophyte infestations of tall fescue pastures result in forage containing ergot alkaloids. Ergot alkaloids act as dopamine agonists which inhibit prolactin synthesis and release by the anterior pituitary. As prolactin gained favor as a bio-marker of “fescue toxicosis” the repeatedly asked question was what does it mean to have decreased serum/plasma prolactin concentrations? This chapter attempts to parse the reported effects of prolactin into either bio-marker or bio-modulator categories. The evidence is clear that prolactin and its associated proteins have direct effects on immune system cells and blood vessels. Substantial evidence supports direct effects of prolactin on appetite/feed intake and hair growth, but the mechanisms are less clear. Consequently, the decreased prolactin concentrations associated with “fescue toxicosis” are both a bio-marker (dopamine agonist effects) and a bio-modulator (impaired vascular and immune function).