EFFECT OF GLUCOSE-ADMINISTRATION DURING THE ESTROUS-CYCLE ON SERUM HORMONE PROFILES, MESSENGER-RNA FOR STEROIDOGENIC ENZYMES, AND BREEDING PERFORMANCE OF EWES

Thirty mature Debouillet ewes were used to examine effects of exogenou s glucose on endocrine, ovarian, and reproductive responses. Treatment s were administered from d 5 through 15 of a normal estrous cycle (d 0 = estrus). Fifteen ewes received daily i.p. injections containing 100 mt of saline (.9%, control), and 15 ewes received daily i.p. injectio ns containing 50 g of glucose (100 mt of 50% dextrose). Ovaries were r emoved from five ewes per group on d 15, and luteal mRNA encoding ster oidogenic enzymes and follicular fluid progesterone (P-4) were determi ned. Serum glucose in treated ewes increased rapidly after injection a nd remained elevated(P < .01) for 4 h after treatment on d 10 and 14 c ompared with control values. Serum insulin concentration was also grea ter (P < .01) after glucose treatment on d 10 and 14, but serum growth hormone concentration was similar (P > .10) in both groups on these d ays. Serum LH concentration and pulsatility were not altered by glucos e injection (P > .15). Serum P-4 remained elevated longer (P < .05) du ring the estrous cycle in treated than in control ewes. Corpora lutea from treated ewes also had more (P < .10) mRNA encoding for cytochrome P-450 side-chain cleavage enzyme; but mRNA for 3 beta-hydroxysteriod dehydrogenase/Delta(5)-Delta(4) isomerase and follicular fluid P-4 wer e similar (P > .40) between groups. Glucose-treated ewes conceived lat er (P < .10) and produced fewer lambs (P < .10) than did controls. The se data indicate that exogenous glucose and(or) the subsequent increas ed serum insulin resulted in ovarian changes associated with elevated luteal P-4 production.