Comparison of glucose, fructose, ascorbic acid and glucosephosphate isomerase enzymatic activity in uterine flushings from nonpregnant and pregnant gilts and pony mares

Abstract

In Experiment 1, 40 gilts and 30 pony mares were used to characterize changes in glucose, fructose, ascorbic acid and glucosephosphate isomerase (GPI) enzymatic activity in uterine flushings collected either during the estrous cycle or early pregnancy. Total recoverable glucose was greater (P<0.01) in uterine flushings from pregnant gilts, but pregnancy status had no effect on total recoverable glucose in pony mare uterine flushings. Fructose was undetectable in uterine flushings from nonpregnant gilts and pony mares and pregnant gilts and pony mares prior to Day 14, but occurred in increasing amounts between Days 14 and 18 or 20 of pregnancy. In Experiment 2, it was demonstrated that the porcine conceptus is the primary source, if not the sole source of fructose. Total recoverable ascorbic acid in uterine flushings was not affected by pregnancy in gilts, but was greater (P<0.01) in pregnant versus nonpregnant pony mares. In both species, total recoverable ascorbic acid was affected (P<0.01) by day of estrous cycle and pregnancy. The GPI enzyme allows for the interconversion of glucose-6-PO 4 and fructose-6-PO 4. GPI total and specific activities were greater (P<0.01) for pregnant than nonpregnant gilts and pony mares. The periods of greatest GPI activity were temporally associated with elevated estrogens of either ovarian or blastocyst origin. Results from Experiment 3 indicated a marked increase (P<0.01) in GPI activity in uterine flushings from gilts treated with estradiol valerate. Results of this study indicate that glucose (gilt only), fructose, ascorbic acid and GPI activity are increased in uterine flushings of gilts and pony mares during early pregnancy. The increase in these constituents may reflect increased carbohydrate metabolism in ways which are uniquely beneficial to conceptus development in ungulates.