PARENT SESSION
PLATFORM SESSION 20: FEMALE REPRODUCTIVE TRACT 2
Chair: Brenner, Robert¹, ¹
Co-chair: Bowen-Shauver, Jennifer¹, ¹
Harborside B
2:00 PM-4:00 PM

(441) DEVELOPMENTAL REGULATION OF HOXA-10 AND HOXA-11 EXPRESSION IN NEONATAL AND ADULT PORCINE UTERINE TISSUES.

Bartol, Frank¹, Lin, Chunru¹, Tarleton, Becky¹, McLean, Sarah¹, Braden, Timothy², Wiley, Anne¹, ¹ Department of Animal Sciences, Auburn, AL² Department of Anatomy, Physiology and Pharmacology, Auburn, AL

ABSTRACT- Products of the Hoxa gene cluster direct patterning of Mullerian duct derivatives. Steroid-sensitive Hoxa-10 and Hoxa-11 expression has been described for neonatal and adult murine and adult human uteri. Disruption of murine Hoxa-10 and -11 expression can alter uterine morphology and compromise endometrial function. In the pig, uterine development between birth (postnatal day = PND 0) and PND 14 is estrogen receptor--dependent and estrogen-sensitive. Estrogen exposure during this period affects uterine phenotype adversely. Here, objectives were to determine if porcine uterine Hoxa-10 or Hoxa-11 expression patterns changed: A) between PND 0 and PND 14; B) on PND 14 after treatment with estradiol valerate (EV); C) during diestrus in endometrium from adult gilts; and D) between neonatal and adult periods. Uteri were obtained by hysterectomy of gilts on: A) PND 0, 7 or 14 (n=4/d); B) PND 14 following treatment from PND 0 with corn oil vehicle or EV (50 g/kg/d; n=6/group); and C) day 4, 8, 12 or 16 post-estrus (estrus = d0; n=6/d). Porcine Hoxa-10 (GenBank AF281156) and Hoxa-11 (AF453292) cDNA templates were used to generate [³²P]- and [³⁵S]UTP-labeled antisense cRNA probes for RNase protection assay (RPA) and in situ hybridization (ISH) analyses of mRNA expression. Both transcripts were detected in all tissues. The Hoxa-10:11 RPA signal ratio was consistently positive (Mean = 3.8). Uterine Hoxa-10 RPA signal did not change significantly from PND 0 to PND 14, but mirrored ISH data indicating increased signal by PND 14. Neonatal uterine Hoxa-11 RPA signal increased (P<.01) 1.25-fold by PND 14. Treatment with EV from PND 0-13 increased uterine Hoxa-10 (P<.04), but not Hoxa-11 RPA signal on PND 14. Endometrial ISH signal intensity for both transcripts was predominantly stromal and greater in neonates than in adults. In cyclic adults, changes in relative levels of Hoxa-10 (P<.05) and Hoxa-11 (P<.01) mRNAs were described by quadratic polynomials. Both were lowest on day 4, increased to day 12 and declined slightly to day 16. Thus, uterine Hoxa-10 and -11 expression is regulated developmentally, subject to estrogen-induced disruption postnatally, modulated systematically during diestrus in adults, and may play a role in establishing and mediating adult uterine function. [USDA-NRI 98-3203-6198]

KEY WORDS: Sus scrofa, Uterus, Homeobox Genes, Development