|
|
||||||||
Division of Endocrinology, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285
The positive correlation between leptin and body fat mass has caused some investigators to speculate that leptin resistance contributes to obesity. Loss of ovarian function in human and rat is associated with increased fat mass gain and increased circulating leptin levels. To study whether ovariectomy produces leptin resistance, Sprague-Dawley female rats were ovariectomized or sham operated and injected with leptin for 35 days. Ovariectomy (OVX) produced hyperphagia and increased gain in both lean and fat mass. Daily leptin injections initially decreased food intake significantly, but feeding gradually increased to a stable level by day 16 and remained at that level for the duration of study. Body composition analysis indicated that chronic injection of leptin to OVX rats dramatically decreased (P < 0.05) fat mass [30 ± 2 (SE) g, vehicle, to 3 ± 1 g, leptin]. Using indirect calorimetry, we observed that OVX did not change energy expenditure or total level of fuel utilization. Leptin administration increased fat utilization and prevented reduction in calorie expenditure that is typically associated with food restriction. Leptin treatment to OVX rats decreased plasma triglyceride, free fatty acid, and insulin concentrations, whereas glucose concentration was normal. Withdrawal of leptin triggered hyperphagia, indicating that leptin biology remained throughout the duration of the chronic treatment. The same dose of leptin produced qualitatively similar data in sham-operated rats. Thus we concluded that the loss of ovarian function in rats is not associated with a change in leptin sensitivity.
rat; indirect calorimetry; energy expenditure; leptin sensitivity; body composition
This article has been cited by other articles:
![]() |
J. M. Y. Jiang, S. M. Sacco, and W. E. Ward Ovariectomy-Induced Hyperphagia Does Not Modulate Bone Mineral Density or Bone Strength in Rats J. Nutr., November 1, 2008; 138(11): 2106 - 2110. [Abstract] [Full Text] [PDF] |
||||
![]() |
W.-J. A. Tsai, K. M. McCormick, D. A. Brazeau, and G. A. Brazeau Estrogen Effects on Skeletal Muscle Insulin-Like Growth Factor 1 and Myostatin in Ovariectomized Rats Experimental Biology and Medicine, November 1, 2007; 232(10): 1314 - 1325. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. J. Mark, R. Tatchum-Talom, D. S. Martin, and K. M. Eyster Effects of estrogens and selective estrogen receptor modulators on vascular reactivity in the perfused mesenteric vascular bed Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2007; 293(5): R1969 - R1975. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. A. Eckel, T. A. Houpt, and N. Geary Estradiol treatment increases CCK-induced c-Fos expression in the brains of ovariectomized rats Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2002; 283(6): R1378 - R1385. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |