|Vallet, Jeffrey - Jeff|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2002
Publication Date: 10/20/2002
Citation: Groothuis, P.G., McGuire, W.J., Vallet, J.L., Grieger, D.M., Davis, D.L. 2002. Retinol and estradiol regulation of retinol binding protein and prostaglandin production by porcine uterine epithelial cells in vitro. Journal of Animal Science. 80(10):2688-2694. Interpretive Summary: Through hormonal manipulation, it is possible to establish pregnancy in female pigs before they undergo natural puberty, but the pigs are subsequently unable to maintain pregnancy. The function of the uterus in prepuberal pigs differs from that of adult pigs, providing an explanation for the inability of prepuberal pigs to maintain pregnancy. However, the normal function of the adult uterus, as well as the differences in the function of the uterus in prepuberal pigs, is not well defined. This experiment demonstrated several differences between prepuberal and adult pigs in the function of cells from the inside lining of the uterus with regard to protein and prostaglandin (hormones derived from fatty acids) secretion. These differences likely contribute to the inability of the prepuberal pig to maintain pregnancy. Definition of the differences between pre- and postpuberal uterine function provides clues to the essential maturational events that take place during puberty, as well as the essential functions carried out by the pig uterus during pregnancy. An understanding of these factors will lead to strategies to optimize uterine function, which in turn, will increase litter size in pigs.
Technical Abstract: Secretion into the uterine lumen follows a precise pattern during early pregnancy. Near the end of the second week of pregnancy and coincident with elongation of conceptuses, retinol binding protein (RBP), estradiol (E2) and prostaglandins E (PGE) and F (PGF) increase in the uterine lumen, and RBP mRNA increases in the endometrium. We examined the potential for E2 (0.1 µM) and retinol (10 µM) to regulate RBP and PG production by cultured luminal (LEC) and glandular (GEC) epithelial cells collected from adult sows and LEC from prepubertal gilts. Endometrial tissue was collected surgically from cyclic and pregnant sows (n=8) on d 10 and 13 postestrus (first d of estrus = d 0) and from 120- and 150-d-old prepubertal gilts that were treated with progesterone (P4) (2.2 mg.kg-1.d-1, n=6) for 14 d prior to tissue collection. The LEC from sows responded to retinol with increased (P<0.07) RBP, PGE, and PGF in culture medium and increased (P<0.07) RBP mRNA but E2 decreased (P<0.05) RBP and RBP mRNA and had no effect on prostaglandins. No E2 or retinol effects on secretions of GEC occurred in vitro, but a d x pregnancy status interaction (P<0.06) affected PGE output by the GEC. Secretion of PGE was greater when GEC were collected on d 10 of pregnancy than from d 10 cyclic or d 13 pregnant or cyclic sows. Both E2 and retinol stimulated (P<0.05) secretion of RBP by LEC isolated from prepubertal gilts, but their effects were not additive. In vivo treatment of prepubertal gilts with P4 increased (P<0.05) RBP and decreased (P<0.05) PG production by LEC in vitro. Therefore responses to E2 and retinol differ between pre- and post-pubertal females and retinol may function in the regulation of endometrial RBP and PG secretion.