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Bioscientifica Proceedings (2020) 17 CPRCPR6 | DOI: 10.1530/biosciprocs.17.0006

CPR2005 Control of Pig Reproduction VII (1) (25 abstracts)

The role of intra-luteal factors in the control of the porcine corpus luteum

J. Gadsby , L. Rose & R. Sriperumbudur and Z. Ge

Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA

In this paper we review three intra-luteal factors and their roles in the corpus luteum (CL). Insulin-like growth factor (IGF)-I, together with its receptor and IGF-binding proteins (IGFBPs), represent an important control system in the CL. IGF-I is a product of small luteal cells and has steroidogenic (i.e. luteotrophic) actions on large luteal cells via the type I receptor, while IGFBPs (e.g. BP-2 and 3; small cells) generally inhibit IGF-Is actions. IGF-I is particularly important in early CL development (up to day 7 of the oestrous cycle) in the pig. Tumour necrosis factor (TNF)-a is a product of luteal macrophages that infiltrate CLs in increasing numbers as the cycle progresses. TNF-a has been shown to play an important role in luteolysis, but we hypothesise that in the pig, this factor plays an additional role during the mid-luteal phase (days 7-13) in promoting the acquisition of luteal sensitivity to the luteolytic actions of prostaglandin (PG)F( = luteolytic sensitivity; LS). Endothelin (ET)-1 is a product of (luteal) endothelial cells, and along with its receptors (ET and ETB)and endothelin-converting enzyme (ECE)-1, represent an intra-luteal system that also plays a role in luteolysis, in association with PGF. Since TNF-α induces endothelial cells to secrete ET-1, we hypothesise that ET- 1 mediates the sensitising effects of TNF-α on the porcine CL during the mid-luteal phase (days 7-13). Finally, we hypothesise that TNF-α and/or ET-1 act to up-regulate luteal protein kinase C (e.g. isoforms βll and ε) activity and thereby sensitises luteal cells to PGF.

© 2005 Society for Reproduction and Fertility

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