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

2004 ◽  
Vol 287 (5) ◽  
pp. R1080-R1085 ◽  
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.

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

2005 ◽  
Vol 288 (6) ◽  
pp. R1486-R1491 ◽  
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.

Sexual dimorphism in vasopressin-induced contraction of rat aorta

1991 ◽  
Vol 260 (2) ◽  
pp. H453-H458 ◽  
Author(s):  
J. N. Stallone ◽  
J. T. Crofton ◽  
L. Share
Keyword(s):  
Estrous Cycle ◽  
Vascular Reactivity ◽  
Rat Aorta ◽  
Isometric Tension ◽  
Female Rats ◽  
Male Rats ◽  
Maximal Response ◽  
Sprague Dawley ◽  
Tension Development ◽  
Sprague Dawley Rats

Previously, we reported that, in the rat, pressor responsiveness to vasopressin (VP) is higher in males than in females during most phases of the estrous cycle. To explore the role of the vasculature in this phenomenon, we examined vascular reactivity to VP in thoracic aortas of male rats and female rats during each phase of the estrous cycle. Aortic rings were prepared from age-matched male and female Sprague-Dawley rats and mounted for isometric tension recording. Maximal response of female aortas to VP (4,246 +/- 163 mg/mg ring dry wt) was more than twice (P less than 0.001) that of male aortas (1,877 +/- 215 mg/mg ring wt). Sensitivity of female aortas to VP was substantially higher (P less than 0.001) than that of male aortas (EC50: 10.9 +/- 0.7 vs. 19.0 +/- 1.6 nM, respectively). Maximal rate of tension development (dT/dtmax) during contraction with VP was nearly twofold higher (P less than 0.01) in female aortas (536 +/- 23 mg/min) than in male aortas (300 +/- 19 mg/min). Maximal response, sensitivity, and dT/dtmax of female aortas did not vary significantly during the estrous cycle. Maximal response of female aortas to phenylephrine (PE; 1,251 +/- 93 mg/mg ring wt) was half that (P less than 0.001) of male aortas (2,546 +/- 194 mg/mg ring wt); sensitivity to PE did not differ significantly (EC50: 0.33 +/- 0.02 vs. 0.38 +/- 0.06 microM, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Estrous Cycle and Temporal Pattern of Feeding in Female Rats

1974 ◽  
Vol 34 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Wilmar A. Jennings
Keyword(s):  
Estrous Cycle ◽  
Direct Observation ◽  
Temporal Pattern ◽  
Indirect Method ◽  
Female Rats ◽  
Albino Rats ◽  
Running Wheel ◽  
Photocell Beam ◽  
Beam Interruption ◽  
Running Wheels

The effects of the estrous cycle and access to running wheels on the pattern of feeding were studied in 24 female albino rats using two methods, an indirect method (photocell beam interruption) and a direct observation of feeding. Although aspects of feeding differed with the method, the following results obtained with both methods. A minimum in the number of bursts of feeding and to a lesser extent the duration of bursts of feeding occurred in estrus. The estrous cycle and access-to-running wheel conditions interacted in affecting the organization of bursts into longer meal-taking periods. The results were considered consistent with the notion that estrus raises the threshold of feeding as a response to stimuli.

scholarly journals Local Cerebral Glucose Utilization in Normal Female Rats: Variations during the Estrous Cycle and Comparison with Males

1985 ◽  
Vol 5 (3) ◽  
pp. 393-400 ◽  
Author(s):  
Astrid Nehlig ◽  
Linda J. Porrino ◽  
Alison M. Crane ◽  
Louis Sokoloff
Keyword(s):  
Estrous Cycle ◽  
Glucose Utilization ◽  
Brain Regions ◽  
Female Rats ◽  
Male Rats ◽  
Normal Male ◽  
Normal Female ◽  
Female Rat ◽  
Males And Females ◽  
The Brain

The quantitative 2-[14C]deoxyglucose autoradiographic method was used to study the fluctuations of energy metabolism in discrete brain regions of female rats during the estrous cycle. A consistent though statistically nonsignificant cyclic variation in average glucose utilization of the brain as a whole was observed. Highest levels of glucose utilization occurred during proestrus and metestrus, whereas lower rates were found during estrus and diestrus. Statistically significant fluctuations were found specifically in the hypothalamus and in some limbic structures. Rates of glucose utilization in the female rat brain were compared with rates in normal male rats. Statistically significant differences between males and females at any stage of the estrous cycle were confined mainly to hypothalamic areas known to be involved in the control of sexual behavior. Glucose utilization in males and females was not significantly different in most other cerebral structures.

scholarly journals Gender Differences in the Effect of Prenatal Methamphetamine Exposure and Challenge Dose of Other Drugs on Behavior of Adult Rats

2013 ◽  
pp. S99-S108 ◽  
Author(s):  
R. ŠLAMBEROVÁ ◽  
E. MACÚCHOVÁ ◽  
K. NOHEJLOVÁ-DEYKUN ◽  
B. SCHUTOVÁ ◽  
L. HRUBÁ ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Adult Male ◽  
Gonadal Hormones ◽  
Female Rats ◽  
Male Rats ◽  
Prenatally Exposed ◽  
Challenge Dose ◽  
Adult Rats ◽  
Male And Female ◽  
Male And Female Rats

The aim of the present study was to compare the response to acute application of several drugs in adult male and female rats prenatally exposed to methamphetamine (MA). Spontaneous locomotor activity and exploratory behavior of adult male and female rats prenatally exposed to MA (5 mg/kg) or saline were tested in a Laboras apparatus (Metris B.V., Netherlands) for 1 h. Challenge dose of the examined drug [amphetamine – 5 mg/kg; cocaine – 5mg/kg; MDMA (3,4-methylenedioxymethamphetamine) – 5 mg/kg; morphine – 5 mg/kg; THC (delta9-tetrahydrocannabinol) – 2 mg/kg] or saline was injected prior to testing. Our data demonstrate that prenatal MA exposure did not affect behavior in male rats with cocaine or morphine treatment, but increased locomotion and exploration in females. Application of amphetamine and MDMA in adulthood increased activity in both sexes, while cocaine and THC only in female rats. Morphine, on the other hand, decreased the activity in the Laboras test in both sexes. As far as sex and estrous cycle is concerned, the present study shows that males were generally less active than females and also females in proestrus-estrus phase of the estrous cycle were more active than females in diestrus. In conclusion, the present study shows that the prenatal MA exposure does not induce general sensitization but affects the sensitivity to drugs dependently to mechanism of drug action and with respect to gonadal hormones.

Melatonin administration entrains female rat activity rhythms in constant darkness but not in constant light

1988 ◽  
Vol 255 (2) ◽  
pp. R237-R242
Author(s):  
E. M. Thomas ◽  
S. M. Armstrong
Keyword(s):  
Estrous Cycle ◽  
Activity Rhythm ◽  
Onset Time ◽  
Circadian System ◽  
Female Rats ◽  
Male Rats ◽  
Constant Darkness ◽  
Female Rat ◽  
Continuous Darkness ◽  
Activity Rhythms

In female rats the luteinizing hormone (LH) is timed by the circadian system and is followed by a display of intense, estrogen-induced running behavior. This proestrous running on the night of ovulation can be used as a marker of the estrous cycle. Entrainment of the mammalian circadian system by exogenous melatonin (MT) has been demonstrated only in the activity rhythms of male rats. The present experiments were designed to study the effect of daily MT injections on activity rhythms and proestrous running of female rats in 1) continuous dim white light (LL) and 2) continuous darkness (DD). In LL, MT injections (50 micrograms/kg or 1 mg/kg) had no discernible effect on activity rhythms. In DD, four of the six MT-treated rats (100 micrograms/kg) entrained to the injection, and a fifth animal showed phase advances in its activity rhythm when onset of activity passed through injection time. The sixth animal was not injected with MT at activity onset time. None of the six control animals showed either effect. MT had no effect on the length of the estrous cycle. Thus MT injections can entrain circadian rhythms of activity and proestrous running in female rats in DD but not in LL.

scholarly journals Changes in RFamide-Related Peptide-1 (RFRP-1)-Immunoreactivity During Postnatal Development and the Estrous Cycle

Endocrinology ◽  
2014 ◽  
Vol 155 (11) ◽  
pp. 4402-4410 ◽  
Author(s):  
Sara R. Jørgensen ◽  
Mille D. Andersen ◽  
Agnete Overgaard ◽  
Jens D. Mikkelsen
Keyword(s):  
Postnatal Development ◽  
Estrous Cycle ◽  
Third Ventricle ◽  
Female Rats ◽  
Male Rats ◽  
Relative Distribution ◽  
Gonadotropin Secretion ◽  
Related Peptide

Abstract GnRH is a key player in the hypothalamic control of gonadotropin secretion from the anterior pituitary gland. It has been shown that the mammalian counterpart of the avian gonadotropin inhibitory hormone named RFamide-related peptide (RFRP) is expressed in hypothalamic neurons that innervate and inhibit GnRH neurons. The RFRP precursor is processed into 2 mature peptides, RFRP-1 and RFRP-3. These are characterized by a conserved C-terminal motif RF-NH2 but display highly different N termini. Even though the 2 peptides are equally potent in vitro, little is known about their relative distribution and their distinct roles in vivo. In this study, we raised an antiserum selective for RFRP-1 and defined the distribution of RFRP-1-immunoreactive (ir) neurons in the rat brain. Next, we analyzed the level of RFRP-1-ir during postnatal development in males and females and investigated changes in RFRP-1-ir during the estrous cycle. RFRP-1-ir neurons were distributed along the third ventricle from the caudal part of the medial anterior hypothalamus throughout the medial tuberal hypothalamus and were localized in, but mostly in between, the dorsomedial hypothalamic, ventromedial hypothalamic, and arcuate nuclei. The number of RFRP-1-ir neurons and the density of cellular immunoreactivity were unchanged from juvenile to adulthood in male rats during the postnatal development. However, both parameters were significantly increased in female rats from peripuberty to adulthood, demonstrating prominent gender difference in the developmental control of RFRP-1 expression. The percentage of c-Fos-positive RFRP-1-ir neurons was significantly higher in diestrus as compared with proestrus and estrus. In conclusion, we found that adult females, as compared with males, have significantly more RFRP-1-ir per cell, and these cells are regulated during the estrous cycle.

scholarly journals A Cognitive Rehabilitation Paradigm Effective in Male Rats Lacks Efficacy in Female Rats

2014 ◽  
Vol 34 (10) ◽  
pp. 1673-1680 ◽  
Author(s):  
Kristopher D Langdon ◽  
Shirley Granter-Button ◽  
Carolyn W Harley ◽  
Frances Moody-Corbett ◽  
James Peeling ◽  
...  
Keyword(s):  
Learning And Memory ◽  
Cognitive Dysfunction ◽  
Cognitive Rehabilitation ◽  
Wheel Running ◽  
Protective Efficacy ◽  
Cognitive Activity ◽  
Female Rats ◽  
Male Rats ◽  
Sprague Dawley ◽  
Bilateral Carotid

Cognitive dysfunction, as a consequence of dementia, is a significant cause of morbidity lacking efficacious treatment. Females comprise at least half of this demographic but have been vastly underrepresented in preclinical studies. The current study addressed this gap by assessing the protective efficacy of physical exercise and cognitive activity on learning and memory outcomes in a rat model of vascular dementia. Forty ovariectomized Sprague-Dawley rats (~6 months old) were exposed to either a diet high in saturated fats and refined sugars or standard laboratory chow and underwent either chronic bilateral carotid occlusion or Sham surgery. Learning and memory abilities were evaluated using standard cognitive outcomes over the ensuing 6 months, followed by histologic analyses of hippocampal CA1 neurons. In Experiment 1, we confirmed hypoperfusion-induced cognitive dysfunction using a 2 × 2 (Surgery × Diet) experimental design, without alterations in hippocampal architecture. In Experiment 2, hypoperfused animals were either exposed to alternating days of physical (wheel running) and cognitive activity (modified Hebb–Williams maze) or sedentary housing. In contrast to males, this combination rehabilitation paradigm did not improve cognition or histopathologic outcomes in hypoperfused animals. These findings, highlighting differences between female and male animals, show the necessity of including both sexes in preclinical experimentation.

AMPK agonist AICAR delays the initial decline in lifetime-apex V̇o2 peak, while voluntary wheel running fails to delay its initial decline in female rats

2016 ◽  
Vol 48 (2) ◽  
pp. 101-115 ◽  
Author(s):  
Ryan G. Toedebusch ◽  
Gregory N. Ruegsegger ◽  
Joshua F. Braselton ◽  
Alexander J. Heese ◽  
John C. Hofheins ◽  
...  
Keyword(s):  
Protein Concentration ◽  
Molecular Mechanisms ◽  
Outcome Measure ◽  
Wheel Running ◽  
Female Rats ◽  
Peak Oxygen Consumption ◽  
Chronological Age ◽  
Primary Hypothesis ◽  
Running Wheels ◽  
Voluntary Wheel

There has never been an outcome measure for human health more important than peak oxygen consumption (V̇o2 peak), yet little is known regarding the molecular triggers for its lifetime decline with aging. We examined the ability of physical activity or 5 wk of 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) administration to delay the initial aging-induced decline in lifetime-apex V̇o2 peak and potential underlying molecular mechanisms. Experiment 1 consisted of female rats with (RUN) and without (NO RUN) running wheels, while experiment 2 consisted of female nonrunning rats getting the AMPK agonist AICAR (0.5 mg/g/day) subcutaneously for 5 wk beginning at 17 wk of age. All rats underwent frequent, weekly or biweekly V̇o2 peak tests beginning at 10 wk of age. In experiment 1, lifetime-apex V̇o2 peak occurred at 19 wk of age in both RUN and NO RUN and decreased thereafter. V̇o2 peak measured across experiment 1 was ∼25% higher in RUN than in NO RUN. In experiment 2, AICAR delayed the chronological age observed in experiment 1 by 1 wk, from 19 wk to 20 wk of age. RUN and NO RUN showed different skeletal muscle transcriptomic profiles both pre- and postapex. Additionally, growth and development pathways are differentially regulated between RUN and NO RUN. Angiomotin mRNA was downregulated postapex in RUN and NO RUN. Furthermore, strong significant correlations to V̇o2 peak and trends for decreased protein concentration supports angiomotin's potential importance in our model. Contrary to our primary hypothesis, wheel running was not sufficient to delay the chronological age of lifetime-apex V̇o2 peak decline, whereas AICAR delayed it 1 wk.

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