Early luteal phase progestin concentration influences endometrial function in pregnant mares

In the horse, it is still unclear if and to what extent low progestin concentration contributes to early conceptus loss. In the present study, we have investigated if reduced or elevated progestin concentration in the early luteal phase influences endometrial function and conceptus development. We h...

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Bibliographic Details
Published in:Theriogenology 2019-02, Vol.125, p.236-241
Main Authors: Beyer, Teresa, Rink, B. Elisabeth, Scarlet, Dragos, Walter, Ingrid, Kunert, Steffen, Aurich, Christine
Format: Article
Language:English
Subjects:
Endometrium
Mare
Progesterone receptor
Progestin concentration
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Summary:In the horse, it is still unclear if and to what extent low progestin concentration contributes to early conceptus loss. In the present study, we have investigated if reduced or elevated progestin concentration in the early luteal phase influences endometrial function and conceptus development. We hypothesized that reduced progestin concentration via delayed downregulation of endometrial progesterone receptors (PR) influences endometrial function in healthy fertile mares while progestin substitution does not. Genitally healthy estrous mares (n = 8; age 4–14 years) were inseminated and treated with either altrenogest (0.044 mg/kg once daily orally) on days 5–10 after ovulation (ALT), cloprostenol (125 μg once daily intramuscularly) on days 0–3 after ovulation (CLO) or left untreated (CON). ALT and CLO treatment were chosen to increase and decrease total peripheral progestin concentration, respectively. Each treatment was given to every mare in consecutive cycles. On day 14 after ovulation, endometrial fluid was collected with a cotton roll inserted into the uterus and an endometrial biopsy for immunohistological demonstration of progesterone (PR) receptor distribution was collected. In endometrial fluid, free amino acid concentrations were analyzed by ion exchange liquid chromatography with an amino acid analyzer. Cell nuclei staining positive for the PR were determined in the luminal and glandular epithelium as well as in the stroma. Pregnancy rate tended to differ among treatments. The percentage of luminal epithelial cells staining positive for PR differed among treatments (p 
ISSN:0093-691X
1879-3231
DOI:10.1016/j.theriogenology.2018.11.018