Effect of the estrous cycle and surgical ovariectomy on energy balance, fuel utilization, and physical activity in lean and obese female rats

Erin D. Giles, Matthew R. Jackman, Ginger C. Johnson, Pepper Schedin, Jordan L. Houser, Paul S. MacLean

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

This study presents an in-depth analysis of the effects of obesity on energy balance (EB) and fuel utilization in adult female rats, over the estrous cycle and immediately after surgical ovariectomy (OVX), to model pre- and postmenopausal states, respectively. Female Wistar rats were fed a high-fat (46%) diet for 16 wk to produce mature lean and obese animals. Stage of estrous was identified by daily vaginal lavage, while energy intake (EI), total energy expenditure (TEE), and fuel utilization were monitored in a multichamber indirect calorimeter and activity was monitored by infrared beam breaks. Metabolic monitoring studies were repeated during the 3-wk period of rapid OVX-induced weight gain. Component analysis of TEE was performed to determine the nonresting and resting portions of energy expenditure. Obesity was associated with a greater fluctuation in EB across the estrous cycle. Cycling obese rats were less active, expended more energy per movement, and oxidized more carbohydrate than lean rats. The changes in EB over the cycle in lean and obese rats were driven by changes in EI. Finally, OVX induced a large positive energy imbalance in obese and lean rats. This resulted primarily from an increase in EI in both groups, with little change in TEE following OVX. These observations reveal a dominant effect of obesity on EB, fuel utilization, and activity levels in cycling rats, which has implications for studies focused on obesity and EB in female rodents.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume299
Issue number6
DOIs
StatePublished - Dec 2010
Externally publishedYes

Fingerprint

Estrous Cycle
Ovariectomy
Energy Metabolism
Obesity
Energy Intake
Vaginal Douching
High Fat Diet
Weight Gain
Wistar Rats
Rodentia
Carbohydrates

Keywords

  • Energy expenditure
  • Energy intake
  • Indirect calorimetry
  • Menopause
  • Spontaneous activity

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Effect of the estrous cycle and surgical ovariectomy on energy balance, fuel utilization, and physical activity in lean and obese female rats. / Giles, Erin D.; Jackman, Matthew R.; Johnson, Ginger C.; Schedin, Pepper; Houser, Jordan L.; MacLean, Paul S.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 299, No. 6, 12.2010.

Research output: Contribution to journalArticle

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