PARENT SESSION
BIOLOGY OF PREGNANCY AND IMMUNE FUNCTION
Harborside C
7:30 AM-10:00 AM

(315) EFFECT OF ESTROGEN ADMINISTRATION ON ENDOMETRIAL ACUTE PHASE PROTEIN GENE EXPRESSION IN PREGNANT GILTS.

Ashworth, Morgan¹, Ross, Jason¹, Malayer, Jerry², Geisert, Rodney¹, ¹ Dept Animal Science, Stillwater, OK² Dept Physiological Sciences, Stillwater, OK

ABSTRACT- Porcine conceptus release of estrogen to establish pregnancy on day 12 is followed by diffuse attachment of the trophoblast to the uterine surface epithelium between days 13 to 18. Exogenous administration of estrogen to gilts on days 9 and 10 of pregnancy causes conceptus degeneration during the period of attachment to the uterine surface. Degeneration of conceptuses is associated with loss of the glycocalyx that normally covers the microvilli on the apical border of uterine epithelium. Members of the inter--trypsin inhibitor heavy chain (IIH) family are involved with stabilization of the extracellular matrix. The present study investigated the possible alteration in endometrial IIH1, IIH2, IIH4 and bikunin gene expression following administration of estrogen on days 9 and 10 of pregnancy. Mated gilts (8/trt group) were treated with either 5 mg estradiol benzoate or corn oil (im) on days 9 and 10 of gestation. Conceptuses were flushed from the uterine horns with 20 ml of Hanks Balanced Salt solution following surgical removal of the uterine horns on either day 10, 12 or 17 of gestation. One uterine horn was opened along its mesometrial border, endometrium harvested and snap frozen in liquid nitrogen. Total RNA was extracted from the endometrium using TRIzol. Endometrial IIH1, IIH2, IIH4 and bikunin gene expression were evaluated by quantitative RT-PCR utilizing a fluorescent reporter and 5' exonuclease assay system. While the appearance of conceptuses flushed from uteri of both treatment groups on days 10 and 12 were normal, conceptus tissue flushed from estrogen treated gilts was fragmented on day 17. No treatment, day or treatment x day effect was detected for endometrial IIH1, IIH2 and IIH4 gene expression. Endometrial bikunin gene expression was affected by day (P<0.001) as gene expression increased 10-fold between day 10 to 17 of gestation. However, administration of estrogen prior to conceptus endogenous synthesis did not significantly affect endometrial bikunin gene expression. Although estrogen administration caused conceptus degeneration, endometrial gene expression for the four II family members was not altered and therefore does not appear to be associated with glycocalyx loss.

KEY WORDS: endometrium, estrogen, pregnancy, conceptus