Effect of glucose administration during the estrous cycle on serum hormone profiles, mRNA for steroidogenic enzymes, and breeding performance of ewes.
Thirty mature Debouillet ewes were used to examine effects of exogenous glucose on endocrine, ovarian, and reproductive responses. Treatments were administered from d 5 through 15 of a normal estrous cycle (d 0 = estrus). Fifteen ewes received daily i.p. injections containing 100 mL of saline (.9%, control), and 15 ewes received daily i.p. injections containing 50 g of glucose (100 mL of 50% dextrose). Ovaries were removed from five ewes per group on d 15, and luteal mRNA encoding steroidogenic enzymes and follicular fluid progesterone (P4) were determined. Serum glucose in treated ewes increased rapidly after injection and remained elevated (P < .01) for 4 h after treatment on d 10 and 14 compared with control values. Serum insulin concentration was also greater (P < .01) after glucose treatment on d 10 and 14, but serum growth hormone concentration was similar (P > .10) in both groups on these days. Serum LH concentration and pulsatility were not altered by glucose injection (P > .15). Serum P4 remained elevated longer (P < .05) during the estrous cycle in treated than in control ewes. Corpora lutea from treated ewes also had more (P < .10) mRNA encoding for cytochrome P450 side-chain cleavage enzyme, but mRNA for 3 beta-hydroxysteriod dehydrogenase/delta 5- delta 4 isomerase and follicular fluid P4 were similar (P > .40) between groups. Glucose-treated ewes conceived later (P < .10) and produced fewer lambs (P < .10) than did controls. These data indicate that exogenous glucose and(or) the subsequent increased serum insulin resulted in ovarian changes associated with elevated luteal P4 production.
Rubio
J M
JM
Department of Animal and Range Sciences, New Mexico State University, Las Cruces 88003, USA.
Hallford
D M
DM
Hawkins
D E
DE
D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis / Q000235:genetics*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism; D015152:Blotting, Northern / Q000379:methods / Q000662:veterinary; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000032:analysis / Q000235:genetics*; D003338:Corpus Luteum / Q000737:chemistry; D004971:Estrus / Q000187:drug effects* / Q000502:physiology; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry; D005947:Glucose / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D007328:Insulin / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D011374:Progesterone / Q000097:blood*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods / Q000662:veterinary; D012756:Sheep / Q000097:blood / Q000378:metabolism*
D001786:Blood Glucose; D007328:Insulin; D012333:RNA, Messenger; D011374:Progesterone; D007986:Luteinizing Hormone; D013006:Growth Hormone; D015096:3-Hydroxysteroid Dehydrogenases; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005947:Glucose