Reproduction in high body condition mares with high versus low leptin concentrations

Reproduction in high body condition mares with high versus low leptin concentrations Previous results from our laboratory indicated that a majority of mares with high body condition scores (BCS) displayed estrous cycles or had considerable follicular activity during the winter. Among these high BCS mares, about 35% of them exhibited a persistent hyperleptinemia and hyperinsulinemia. The current experiment was designed to compare the reproductive characteristics of high BCS mares with hyperleptinemia to those with normal (low) plasma concentrations of leptin during the winter and the first estrous cycle (or the first full cycle encountered for those already cycling). Light horse mares with high BCS (6–8.5) were assigned to groups based on leptin concentrations (8/group): low (<5 ng/mL) and high (>10 ng/mL). Beginning 7 January, mares were assessed every 3 d for follicular activity and then daily once a follicle >25 mm was detected. Mares were subsequently monitored through their first and second ovulations. Leptin concentrations remained higher ( P < 0.001) in mares in the high leptin group over the duration of the experiment. Also, high leptin mares had greater ( P < 0.0001) insulin response to glucose infusion and a faster ( P < 0.05) rate of glucose clearance. One mare with high leptin and three mares with low leptin had progesterone concentrations indicative of the presence of a corpus luteum at the onset of the experiment. Plasma concentrations of LH, FSH, and progesterone did not differ between groups ( P > 0.1) during the first estrous cycle occurring after 7 January. Date of first ovulation after 7 January and interovulatory interval were similar ( P > 0.1) for the two groups, as were estimates of follicular numbers on the ovaries (small, medium, and large; P > 0.1). It is concluded that the perturbations in leptin and insulin secretion observed in some high BCS mares are not associated with alterations in ovarian activity or the estrous cycle during winter and into the period of vernal transition. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Theriogenology Elsevier

Reproduction in high body condition mares with high versus low leptin concentrations

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Publisher
Elsevier
Copyright
Copyright © 2006 Elsevier Inc.
ISSN
0093-691X
eISSN
1879-3231
D.O.I.
10.1016/j.theriogenology.2006.02.033
Publisher site
See Article on Publisher Site

Abstract

Previous results from our laboratory indicated that a majority of mares with high body condition scores (BCS) displayed estrous cycles or had considerable follicular activity during the winter. Among these high BCS mares, about 35% of them exhibited a persistent hyperleptinemia and hyperinsulinemia. The current experiment was designed to compare the reproductive characteristics of high BCS mares with hyperleptinemia to those with normal (low) plasma concentrations of leptin during the winter and the first estrous cycle (or the first full cycle encountered for those already cycling). Light horse mares with high BCS (6–8.5) were assigned to groups based on leptin concentrations (8/group): low (<5 ng/mL) and high (>10 ng/mL). Beginning 7 January, mares were assessed every 3 d for follicular activity and then daily once a follicle >25 mm was detected. Mares were subsequently monitored through their first and second ovulations. Leptin concentrations remained higher ( P < 0.001) in mares in the high leptin group over the duration of the experiment. Also, high leptin mares had greater ( P < 0.0001) insulin response to glucose infusion and a faster ( P < 0.05) rate of glucose clearance. One mare with high leptin and three mares with low leptin had progesterone concentrations indicative of the presence of a corpus luteum at the onset of the experiment. Plasma concentrations of LH, FSH, and progesterone did not differ between groups ( P > 0.1) during the first estrous cycle occurring after 7 January. Date of first ovulation after 7 January and interovulatory interval were similar ( P > 0.1) for the two groups, as were estimates of follicular numbers on the ovaries (small, medium, and large; P > 0.1). It is concluded that the perturbations in leptin and insulin secretion observed in some high BCS mares are not associated with alterations in ovarian activity or the estrous cycle during winter and into the period of vernal transition.

Journal

TheriogenologyElsevier

Published: Sep 1, 2006

References

  • Insulin resistance, polycystic ovary syndrome, and type 2 diabetes mellitus
    Ovalle, F.; Azziz, R.
  • A significant role of leptin in the generation of steroid-induced luteinizing hormone and prolactin surges in female rats
    Kohsaka, A.; Watanobe, H.; Kakizaki, Y.; Habu, S.; Suda, T.
  • Relationship between condition score, physical measurements and body fat percentage in mares
    Henneke, D.R.; Potter, G.D.; Kreider, J.L.; Yeates, B.F.
  • Effect of short term exercise training on insulin sensitivity in obese and lean mares
    Powell, D.M.; Reedy, S.E.; Sessions, D.R.; Fitzgerald, B.P.

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