Effects of prefattening on ovariectomy-induced hyperphagia and weight gain in rats

Noel, R; Fleming, Alison S.

doi:10.1016/s0091-6773(77)91845-4

Cited by 12 publications

(4 citation statements)

References 15 publications

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“…It is important to note that both we and Lemieux et al [37] began the dietary-obesity regimen only after ovariectomy, whereas women are more often obese before menopause. A better model of dietary obesity and menopause may be afforded by designs like that used by Noel and Fleming [75], who made rats obese by force feeding prior to ovariectomy. In this situation, ovariectomy produced similar amounts of excess body mass, which was the only obesity measure, in obese and control rats (~40 and 45 g, respectively, at d 30).…”

Section: Discussionmentioning

confidence: 99%

Ovariectomy and overeating palatable, energy-dense food increase subcutaneous adipose tissue more than intra-abdominal adipose tissue in rats

et al. 2011

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BackgroundMenopause is associated with increased adiposity, especially increased deposition of intra-abdominal (IA) adipose tissue (AT). This differs from common or 'dietary' obesity, i.e., obesity apparently due to environmentally stimulated overeating, in which IAAT and subcutaneous (S) AT increase in similar proportions. The effect of menopause on adiposity is thought to be due to the decreased secretion of ovarian estrogens. Ovariectomy in rats and other animals is a commonly used model of menopause. It is well known that ovariectomy increases adiposity and that this can be reversed by estradiol treatment, but whether ovariectomy selectively increases IAAT has not been measured directly. Therefore, we used micro-computed tomography (microCT) to investigate this question in both chow-fed and dietary-obese rats.MethodsOvariectomized, ovariectomized and estradiol treated, and sham-operated (intact) rats were fed chow or chow plus Ensure (Abbott Nutrition; n = 7/group). Total (T) AT, IAAT and SAT were measured periodically by microCT. Regional distribution of AT was expressed as IAAT as a percentage of TAT (%IAAT). Excesses in these measures were calculated with respect to chow-fed intact rats to control for normal maturational changes. Chemical analysis of fat was done in chow-fed intact and ovariectomized rats at study end. Data were analyzed by t-tests and planned comparisons.ResultsBody mass, TAT, total fat mass, fat-free body mass, and %IAAT all increased in chow-fed intact rats during the 41 d study. In chow-fed rats, ovariectomy increased excess body mass, TAT, fat mass, fat-free body mass, and SAT, but had little effect on IAAT, in chow-fed rats, leading to a decrease in %IAAT. Ensure feeding markedly increased SAT, IAAT and TAT and did not significantly affect %IAAT. Ovariectomy had similar effects in Ensure-fed rats as in chow-fed rats, although less statistically reliable. Estradiol treatment prevented all the effects of ovariectomy.ConclusionsBoth ovariectomy in rats and menopause are associated with increased TAT. After ovariectomy, fat is preferentially deposited as SAT and lean body mass increases, whereas after menopause fat is preferentially deposited as IAAT and lean body mass decreases. These opposite effects of ovariectomy and menopause on regional AT distribution and lean body mass indicate that ovariectomy in rats is not a homologous model of menopause-associated changes in body composition that should be used with great caution in investigations of adiposity-related diseases.

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Section: Discussionmentioning

confidence: 99%

Ovariectomy and overeating palatable, energy-dense food increase subcutaneous adipose tissue more than intra-abdominal adipose tissue in rats

et al. 2011

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“…These actions of estradiol have been interpreted as lowering the set point for body weight (see Wade, 1976); that is, changes in food intake and body weight that accompany manipulation of estrogen levels have been seen as the result of an attempt to stabilize 1127 body weight at a new level. Often-cited support for this hypothesis is the ovariectomy-induced estrogen withdrawal results in a permanently elevated body weight (Tarttelin & Gorski, 1973), that ovariectomized rats defend their increased body weight after food deprivation, and that prefattening reduces ovariectomy-induced weight gain (Noel & Fleming, 1977).…”

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confidence: 99%

Estrus- and ovariectomy-induced body weight changes: Evidence for two estrogenic mechanisms.

Mueller¹,

Hsiao²

1980

Journal of Comparative and Physiological Psychology

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Estrogenic modulation of body weight in female rats is usually thought to result indirectly from estrogenic modulation of food intake. The data presented here suggest, however, that estrogens influence body weight by at least two mechanisms, one of which is independent of changes in food intake. When female rats were ovariectomized (Ovx) and food intake was limited to preoperative levels, the Ovx animals nonetheless gained large amounts of body weight. Although Ovx rats gained more weight than controls on the same amount of food, during 33 hr of food deprivation Ovx and control animals lost body weight at the same rate, which indicates that the prefacing metabolic rates of the two groups were generally similar. Examination of recovery from food deprivation suggested that the rate of weight gain after Ovx was very gradual During the first 40 days after surgery, the ano-nasal lengths of Ovx rats increased twice as fast as the ano-nasal lengths of the intact rats, which suggests a mechanism for the gradual increase in body weight induced by Ovx The body weights of intact rats followed a regular 4-day cycle during ad lib feeding, but when the estrus-associated decrease in food intake was prevented, the cyclic body weight changes were dramatically altered. Thus estrogens appear to regulate body weight by at least two mechanisms' modulation of food intake (cycling females) and modulation of ano-nasal growth or other metabolic processes (Ovx females).

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“…This finding supports our previous suggestion (Mueller & Hsiao, 1980) that conclusions about the effects of EB on body weight may not be generalizable from Ovx to intact animals. Noel and Fleming (1977) reported that prefattening reduces weight gain after Ovx. The present experiment is not strictly comparable with prefattening, since the animals were maintained on different diets throughout the experiment.…”

Section: Resultsmentioning

confidence: 99%

Effectiveness of estradiol in preventing and reversing obesity induced by ovariectomy and high-caloric diet in female rats.

Mueller¹,

Hsiao²

1981

Journal of Comparative and Physiological Psychology

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Estrogens have recently been described as being most effective in restraining the food intake and body weight of female rats that face impending obesity. A corollary is that estrogens are more effective in preventing than reversing the body weight gain that accompanies ovariectomy (Ovx). Four experiments examined the effects of estradiol benzoate (EB) on food intake, body weight, ano-nasal length, and body weight to body length ratio (Lee index) of ovariectomized and intact rats maintained on control or high-fat diets, and of Ovx and intact rats that had been reduced by deprivation. Estradiol benzoate was highly effective in preventing the increase in food intake, body weight, and ano-nasal growth after Ovx. It was relatively ineffective in reversing body weight gain after Ovx. However, when ano-nasal length was also considered, EB was effective in returning Ovx rats to an appropriate body weight for their increased ano-nasai length. About 40% of the body weight gain after Ovx appears to be due to skeletal growth and the increased tissue mass necessary to maintain it. Intact rats fed a high-caloric diet did not exhibit an increased rate of ano-nasal growth, which indicates that the skeletal growth that occurs after Ovx is not simply a result of increased food intake. Estradiol benzoate was eventually effective in reducing the body weights of intact rats maintained on a high-fat diet, but it also reduced the body weights of intact control rats. The high-fat diet did not alter the amount of weight gained after Ovx. It is concluded that EB modulates food intake and body weight by multiple mechanisms, one of which is by modulating skeletal growth. The nature of the effect of EB on the body weight of intact rats suggests that this effect occurs by still another mechanism.

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Effects of prefattening on ovariectomy-induced hyperphagia and weight gain in rats

Cited by 12 publications

References 15 publications

Ovariectomy and overeating palatable, energy-dense food increase subcutaneous adipose tissue more than intra-abdominal adipose tissue in rats

Ovariectomy and overeating palatable, energy-dense food increase subcutaneous adipose tissue more than intra-abdominal adipose tissue in rats

Estrus- and ovariectomy-induced body weight changes: Evidence for two estrogenic mechanisms.

Effectiveness of estradiol in preventing and reversing obesity induced by ovariectomy and high-caloric diet in female rats.

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