Rats fed only during the light period are resistant to stress-induced weight loss

Ruth B.S. Harris, Jun Zhou, Tiffany Mitchell, Sadie Hebert, Donna H. Ryan

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Repeated restraint stress (3 h/day for 3 days) causes a chronic down-regulation of body weight in rats. This study determined whether weight loss was influenced by the time of day that rats had access to food or that stress was applied. Groups of male Sprague-Dawley rats were fed a 40% kcal fat diet with food given ad libitum, only during the light phase or only during the dark phase. After 2 weeks of adaptation, rats within each feeding treatment were divided into four groups. One was exposed to repeated restraint at the start of the light phase, another was restrained at the start of the dark phase and the remaining groups were nonstressed controls for restrained rats. Body weight was significantly reduced in ad libitum- and dark-fed restrained rats, compared with nonstressed controls, from Day 2 of restraint, regardless of the time of day that they were stressed. There was no significant effect of restraint on weight change of light-fed rats. Food intake was inhibited by stress in ad libitum- and dark-fed rats, but it was not changed in light-fed rats. Serum corticosterone was increased by restraint in all rats irrespective of feeding schedule. This study demonstrates that stress-induced weight loss only occurs when rats have food available during their normal feeding period (dark phase) and is not determined by increased corticosterone release.

Original languageEnglish (US)
Pages (from-to)543-550
Number of pages8
JournalPhysiology and Behavior
Volume76
Issue number4-5
DOIs
StatePublished - Jan 1 2002

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Weight Loss
Light
Corticosterone
Food
Body Weight
Sprague Dawley Rats
Appointments and Schedules
Down-Regulation
Eating
Fats
Diet
Weights and Measures
Serum

Keywords

  • Body weight
  • Food intake
  • HPA axis

Cite this

Rats fed only during the light period are resistant to stress-induced weight loss. / Harris, Ruth B.S.; Zhou, Jun; Mitchell, Tiffany; Hebert, Sadie; Ryan, Donna H.

In: Physiology and Behavior, Vol. 76, No. 4-5, 01.01.2002, p. 543-550.

Research output: Contribution to journalArticle

Harris, Ruth B.S. ; Zhou, Jun ; Mitchell, Tiffany ; Hebert, Sadie ; Ryan, Donna H. / Rats fed only during the light period are resistant to stress-induced weight loss. In: Physiology and Behavior. 2002 ; Vol. 76, No. 4-5. pp. 543-550.
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