PARENT SESSION

(W519) EFFECTS OF ESTRADIOL ON EXPRESSION OF CONNEXIN (Cx)43, Cx37, Cx32, AND Cx26 IN ENDOMETRIAL TISSUES OF OVARIECTOMIZED (OVX) EWES.

Johnson, Mary Lynn¹, Grazul-Bilska, Anna¹, Borowczyk, Ewa¹, Redmer, Dale¹, Reynolds, Lawrence¹, ¹ North Dakota State University, Fargo, ND

ABSTRACT- The relationship between estradiol (E2) and Cx expression may be associated with cellular interactions, secretory functions, and/or tissue growth within uterine tissue compartments. To evaluate effects of E2 on the time-course of expression of Cx43, Cx37, Cx32 and Cx26, endometrial caruncular (CAR) and intercaruncular (ICAR) tissues were obtained at 0, 2, 4, 8, 16, and 24 h after placing a subcutaneous E2 implant (100 mg in Silastic) into long-term OVX ewes (n=4-6 per group). Expression of mRNA for Cx43, Cx37, Cx32, and Cx26 was quantified with real time RT-PCR and ovine-specific probe/primers from Applied Biosystems (Primer Express, Foster City, CA). Values were compared to 0 h for all genes evaluated. Expression of Cx43 mRNA in CAR increased by 2.7-fold at 4 h (P<0.06), 3-fold at 8 h (P<0.05), 3.8-fold at 16 h (P<0.01), and >4-fold (P<0.01) at 24 h after E2 treatment. Expression of Cx43 mRNA in ICAR increased by >4-fold at 8 to 16 h (P<0.01) and remained at >2.7-fold at 24 h (P=0.09) after E2 treatment. Expression of Cx37 increased by 3 to 4-fold in CAR at 2 through 8 h (P<0.05) after E2 treatment, whereas in ICAR, a 4-fold increase in Cx37 was seen at 4 to 8 h (P<0.05) after E2 treatment. Expression of Cx32 mRNA in CAR decreased by approximately 1.7-fold at 2 h (P<0.06), by 2-fold at 4 h (P<0.01), and by approximately 2.5-fold at 8 through 24 h (P<0.01) after E2 treatment. However, in ICAR, E2 initially increased expression of Cx32 mRNA by 1.7-fold at 2 h (P<0.08), then expression of Cx32 mRNA decreased by nearly 7-fold (P<0.06) at 8 h, returning to 0 h values at 16 through 24 h after E2 treatment. Expression of Cx26 mRNA increased in CAR by 16-fold at 4 h (P<0.02), 24-fold at 8 h (P<0.01), and >30-fold at 16 through 24 h (P<0.01) after E2 treatment. Expression of Cx26 mRNA in ICAR increased 36-fold at 4 h (P<0.01), >40-fold at 8 h (P<0.01), 36-fold at 16 h (P<0.01), and was maintained at a 30-fold increase at 24 h (P<0.01) after E2 treatment. At the tissue level, Cx43 mRNA expression was greater (P<0.05) in CAR versus ICAR. However, for Cx37, Cx32, and Cx26 mRNA expression was similar in CAR and ICAR. Thus, estradiol regulates expression of several Cx in endometrial tissues of sheep, which indicates the role of gap junctions in E2-regulated uterine function. Supported by NIH grant HL64141 to LPR and DAR.

KEY WORDS: gap junction, uterus, estradiol, connexin