Abstract: 79

PORCINE PLACENTAL 11-HYDROXYSTEROID DEHYDROGENASE (11-HSD) DURING EARLY GESTATION.

H. G. Klemcke^{1 *}, R. Sampath-Kumar² , K. Yang² , J. L. Vallet^{1 *}, R. K. Christenson^{1 *}
USDA, ARS, U.S. Meat Animal Research Center, Clay Center, Nebraska ¹
University of Western Ontario, Lawson Research Institute, St. Joseph's Health Centre, London, ON, Canada ²

Optimal fetal cortisol levels may be important to fetal development. 11-HSD helps regulate cortisol levels via interconversion of cortisol to inactive cortisone. Hence, effects of gestational age, breed, and uterine environment on mRNA and activity of two isoforms, 11-HSD1 and 11-HSD2, were examined. Placentae were obtained from intact (INT) and unilaterally hysterectomized-ovariectomized (UHO) white crossbred and intact Meishan (ME) gilts on days (d) 24, 30, and 40 of gestation (n = 5-6 gilts/treatment/day). Enzyme mRNA was measured using Northern analyses, and activities were determined by radiometric assays. 11-HSD1 mRNA was absent on d 24, did not differ among treatments on d 30-40, but increased 35% (p < 0.01) between d 30 and d 40 in all treatments. 11-HSD2 mRNA was present each day. In UHO on d 30, it was 56% lower (p < 0.02) than other days and was 45% lower (p = 0.04) than in INT and ME. Low 11-HSD1 activity (n = 3/treatment/day) existed on d 24 (1 ± 13 pmol/10 min/mg protein) but increased by d 30–40 (28 ± 13). 11-HSD2 did not differ among treatments but increased (p < 0.01) between d 24 (17 ± 9 pmol/10 min/mg protein) and d 40 (74 ± 11). The predominance of 11-HSD2 suggests a net conversion of cortisol to cortisone that alleges a necessity for low cortisol. A crowded uterine environment (UHO) was associated with reduced 11-HSD2 mRNA at d 30 that may relate to decreased fetal survival in UHO.

    This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.