The effect of wheel running and the estrous cycle on energy expenditure in female rats

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.

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Diet-induced hyperphagia in the rat is influenced by sex and exercise

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00424.2004 ◽

2004 ◽

Vol 287 (5) ◽

pp. R1080-R1085 ◽

Cited By ~ 28

Author(s):

Lisa A. Eckel ◽

Shelley R. Moore

Keyword(s):

Estrous Cycle ◽

Wheel Running ◽

Caloric Intake ◽

Female Rats ◽

Male Rats ◽

Milk Diet ◽

Daily Caloric Intake ◽

Running Wheels

Caloric intake is increased in rats fed a diet containing greater fat or sugar than that found in laboratory chow. Because such diet-induced hyperphagia has been studied primarily in sedentary male rats, our goal here was to investigate the effects of sex and exercise on caloric intake of a diet (chow supplemented with sweet milk) chosen for its ability to stimulate hyperphagia. Rats were housed individually in cages that provided access to running wheels, and daily caloric intake of chow alone and then chow plus sweet milk was monitored during sedentary and active conditions. In sedentary rats, chow intake was greater in males compared with females. Wheel running produced similar decreases in chow intake in both sexes. Availability of the chow plus milk diet increased caloric intake compared with that observed in chow-fed rats. This diet-induced hyperphagia was significantly greater in sedentary females (35.7 ± 3.1% increase) relative to sedentary males (9.1 ± 2.2% increase). In addition, 35% of sedentary females consuming the chow plus milk diet developed estrous cycle disruptions. Wheel running decreased intake of the chow plus milk diet in both sexes. In active males, diet-induced hyperphagia was abolished; caloric intake was reduced to that observed during chow feeding. In active female rats, diet-induced hyperphagia was attenuated but not abolished; caloric intake of the chow plus milk diet remained greater than that observed during chow feeding. We conclude that female rats are more vulnerable than male rats to this form of diet-induced hyperphagia.

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Shifts in preferred learning strategy across the estrous cycle in female rats

Hormones and Behavior ◽

10.1016/j.yhbeh.2004.01.005 ◽

2004 ◽

Vol 45 (5) ◽

pp. 330-338 ◽

Cited By ~ 146

Author(s):

Donna L Korol ◽

Emily L Malin ◽

Kristine A Borden ◽

Rachel A Busby ◽

Julia Couper-Leo

Keyword(s):

Estrous Cycle ◽

Learning Strategy ◽

Female Rats

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Gonadal hormones organize and modulate the circadian system of the rat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1981.241.1.r62 ◽

1981 ◽

Vol 241 (1) ◽

pp. R62-R66 ◽

Cited By ~ 11

Author(s):

H. E. Albers

Keyword(s):

Testosterone Propionate ◽

Wheel Running ◽

Activity Rhythm ◽

Gonadal Hormones ◽

Circadian System ◽

Female Rats ◽

Constant Darkness ◽

Before And After ◽

Free Running ◽

Free Running Period

The circadian wheel-running rhythms of gonadectomized adult male, female, and perinatally androgenized female rats, maintained in constant darkness, were examined before and after implantation of Silastic capsules containing cholesterol (C) or estradiol-17 beta (E). The free-running period of the activity rhythm (tau) before capsule implantation tended to be shorter in animals exposed to perinatal androgen. Administration of C did not reliably alter tau in any group. E significantly shortened tau in 100% of females injected with oil on day 3 of life. In females, injected with 3.5 micrograms testosterone propionate on day 3, and males, E shortened or lengthened tau, with the direction and magnitude of this change in tau inversely related to the length of the individual's pretreatment tau. These data indicate that the presence of perinatal androgen does not eliminate the sensitivity of the circadian system of the rat to estrogen, since estrogen alters tau in a manner that depends on its pretreatment length.

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Eating and Wheel Running Across the Estrous Cycle in Rat Lines Selectively Bred on a Taste Phenotype

Physiology & Behavior ◽

10.1016/j.physbeh.2021.113552 ◽

2021 ◽

pp. 113552

Author(s):

Nancy K. Dess ◽

Alexis T. Funaki ◽

Benjamin G. Fanson ◽

Rhea Bhatia ◽

Clinton D. Chapman

Keyword(s):

Estrous Cycle ◽

Wheel Running ◽

Taste Phenotype

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The anorectic effect of fenfluramine is influenced by sex and stage of the estrous cycle in rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00779.2004 ◽

2005 ◽

Vol 288 (6) ◽

pp. R1486-R1491 ◽

Cited By ~ 24

Author(s):

Lisa A. Eckel ◽

Heidi M. Rivera ◽

Deann P. D. Atchley

Keyword(s):

Food Intake ◽

Estrous Cycle ◽

Female Rats ◽

Male Rats ◽

Gonadal Hormone ◽

Estrous Female ◽

Male And Female Rats ◽

Daily Food ◽

Hormone Status ◽

Anorectic Effect

The controls of food intake differ in male and female rats. Daily food intake is typically greater in male rats, relative to female rats, and a decrease in food intake, coincident with the estrous stage of the ovarian reproductive cycle, is well documented in female rats. This estrous-related decrease in food intake has been attributed to a transient increase in the female rat's sensitivity to satiety signals generated during feeding bouts. Here, we investigated whether sex or stage of the estrous cycle modulate the satiety signal generated by fenfluramine, a potent serotonin (5-HT) releasing agent. To examine this hypothesis, food intake was monitored in male, diestrous female, and estrous female rats after intraperitoneal injections of 0, 0.25, and 1.0 mg/kg d-fenfluramine. The lower dose of fenfluramine decreased food intake only in diestrous and estrous females, suggesting that the minimally effective anorectic dose of fenfluramine is lower in female rats, relative to male rats. Although the larger dose of fenfluramine decreased food intake in both sexes, the duration of anorexia was greater in diestrous and estrous female rats, relative to male rats. Moreover, the magnitude of the anorectic effect of the larger dose of fenfluramine was greatest in estrous rats, intermediate in diestrous rats, and least in male rats. Thus our findings indicate that the anorectic effect of fenfluramine is modulated by gonadal hormone status.

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Female rats selectively bred for high intrinsic aerobic fitness are protected from ovariectomy-associated metabolic dysfunction

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00401.2014 ◽

2015 ◽

Vol 308 (6) ◽

pp. R530-R542 ◽

Cited By ~ 34

Author(s):

Victoria J. Vieira-Potter ◽

Jaume Padilla ◽

Young-Min Park ◽

Rebecca J. Welly ◽

Rebecca J. Scroggins ◽

...

Keyword(s):

Physical Activity ◽

Insulin Resistance ◽

Skeletal Muscle ◽

Energy Expenditure ◽

Aerobic Fitness ◽

Resting Energy Expenditure ◽

Female Rats ◽

Metabolic Dysfunction ◽

Spontaneous Physical Activity ◽

Resting Energy

Ovariectomized rodents model human menopause in that they rapidly gain weight, reduce spontaneous physical activity (SPA), and develop metabolic dysfunction, including insulin resistance. How contrasting aerobic fitness levels impacts ovariectomy (OVX)-associated metabolic dysfunction is not known. Female rats selectively bred for high and low intrinsic aerobic fitness [high-capacity runners (HCR) and low-capacity runners (LCR), respectively] were maintained under sedentary conditions for 39 wk. Midway through the observation period, OVX or sham (SHM) operations were performed providing HCR-SHM, HCR-OVX, LCR-SHM, and LCR-OVX groups. Glucose tolerance, energy expenditure, and SPA were measured before and 4 wk after surgery, while body composition via dual-energy X-ray absorptiometry and adipose tissue distribution, brown adipose tissue (BAT), and skeletal muscle phenotype, hepatic lipid content, insulin resistance via homeostatic assessment model of insulin resistance and AdipoIR, and blood lipids were assessed at death. Remarkably, HCR were protected from OVX-associated increases in adiposity and insulin resistance, observed only in LCR. HCR rats were ∼30% smaller, had ∼70% greater spontaneous physical activity (SPA), consumed ∼10% more relative energy, had greater skeletal muscle proliferator-activated receptor coactivator 1-alpha, and ∼40% more BAT. OVX did not increase energy intake and reduced SPA to the same extent in both HCR and LCR. LCR were particularly affected by an OVX-associated reduction in resting energy expenditure and experienced a reduction in relative BAT; resting energy expenditure correlated positively with BAT across all animals ( r = 0.6; P < 0.001). In conclusion, despite reduced SPA following OVX, high intrinsic aerobic fitness protects against OVX-associated increases in adiposity and insulin resistance. The mechanism may involve preservation of resting energy expenditure.

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