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PGE2 secretion by the conceptus and binding by non‐pregnant endometrium in the horse
Author(s) -
VANDERWALL D. K.,
WOODS G. L.,
WEBER J. A.,
LICHTENWALNER A. B.
Publication year - 1993
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1993.tb04818.x
Subject(s) - conceptus , corpus luteum , horse , dissociation constant , endometrium , endocrinology , secretion , medicine , andrology , biology , chemistry , pregnancy , fetus , receptor , ovary , paleontology , genetics
Summary Conceptus PGE 2 secretion was determined by incubating equine conceptuses (7/day) in vitro for 24 h. Day‐11, ‐13 and ‐15 conceptuses secreted (mean ± sem) 91.2 ± 23.7, 92.8 ± 15.9 and 170.8 ± 24.9 ng PGE 2 /24 h, respectively. Day‐15 conceptuses secreted more (P<0.05) PGE 2 than Day‐11 or Day‐13 conceptuses. Conceptus diameter and PGE 2 secretion were positively correlated (R 2 = 0.52; P<0.001). Endometrial membrane preparations from non‐pregnant mares (6/day) were incubated with [ 3 H]PGE 2 and nonradioactive PGE 2 . The concentrations of unoccupied endometrial PGE 2 binding sites on Days 11, 13 and 15 were 116.2 ± 17.7, 93.3 ± 12.4 and 57.2 ± 7.3 fmol/mg protein, respectively. The binding site concentration was higher (P<0.05) on Day 11 than Day 15. The dissociation constant of the binding reaction on Days 11, 13 and 15 was 1.94 ± 0.35, 1.55 ± 0.11 and 1.64 ± 0.25 nM, respectively. There was no difference (P>0.10) in the dissociation constant between days. These results demonstrate that equine conceptuses secrete PGE 2 , and non‐pregnant equine endometrium specifically binds PGE 2 during the period of maintenance of the corpus luteum.