Ovarian hormones inhibit fat intake under binge-type conditions in ovariectomized rats

Physiol Behav. 2008 Oct 20;95(3):501-7. doi: 10.1016/j.physbeh.2008.07.021. Epub 2008 Jul 22.

Abstract

Binge eating is more common in females than in males. This study investigated the effects of ovarian hormones on binge-eating behavior in a diet-related rat model. Six groups of ovariectomized Sprague-Dawley rats were used (n=13/group). All rats had continuous access to chow and water throughout the study. One half of the rats were injected every fourth day with estradiol benzoate (2 microg/100 microl sesame oil) and progesterone (500 microg/100 microl sesame oil); the other half received only the sesame oil vehicle. Three feeding protocols were tested in each hormone injection condition: (1) chow only: no additional dietary fat access; (2) low-restriction: 1-h fat access every day; (3) high-restriction: 1-h fat access on Monday, Wednesday, and Friday. As previously reported in intact male and female rats, the high-restriction groups exhibited binge-like increases in 1-h energy intake during fat access. The major new finding of this study is that 1-h energy intake was tonically, but not cyclically, reduced in the hormone-treated high-restriction (binge) rats. Specifically, both low- and high-restriction hormone-treated rats consumed significantly less energy than did the oil-treated rats during the 1-h fat period (p<0.0001) and overall (p<0.0001), indicating a tonic inhibition of eating. However, food intake during the 1-h fat access period was also cyclically reduced in the hormone-treated low-restriction rats, but not in the hormone-treated high-restriction rats. These results indicate that the normal cyclic inhibitory influence of ovarian hormones on eating, but not their normal tonic inhibitory influence, is disrupted by conditions leading to binge-type eating.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Behavior, Animal
  • Body Composition / drug effects
  • Body Weight / drug effects
  • Body Weight / physiology
  • Bulimia / drug therapy*
  • Bulimia / physiopathology
  • Dietary Fats / administration & dosage*
  • Disease Models, Animal
  • Eating / drug effects*
  • Energy Intake / drug effects
  • Estradiol / administration & dosage
  • Estradiol / analogs & derivatives*
  • Female
  • Ovariectomy*
  • Progesterone / administration & dosage*
  • Rats
  • Rats, Sprague-Dawley
  • Time Factors

Substances

  • Dietary Fats
  • estradiol 3-benzoate
  • Progesterone
  • Estradiol