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Query: UMLS:C0020505 (hyperphagia)
 6,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The obese Zucker rat (fa/fa) is an animal model for genetic obesity characterized by hyperphagia, hyperinsulinemia, and severe insulin resistance in peripheral tissues. Adrenal steroids seem to play an important role in the onset of fatty syndrome in these animals. There is strong evidence of abnormal regulation of the hypothalamic-pituitary-adrenal axis in obese Zucker rats. Considering the physiological function of arginine vasopressin (AVP) as an adrenocorticotropic hormone secretagogue, the present study was carried out to investigate the role of glucocorticoids in the control of hypothalamic AVP systems in lean and obese Zucker rats. In the first experiment, mifepristone (RU 38486), a glucocorticoid receptor antagonist, was administered for 4 days (10 mg/kg orally twice daily), and the expression of AVP mRNA in hypothalamic paraventricular and supraoptic nuclei was measured using in situ hybridization, and the concentrations of AVP in the pituitary gland and in the median eminence were quantified. Plasma corticosterone levels were also analyzed. Mifepristone treatment resulted in a threefold increase in plasma corticosterone levels in lean Zucker rats, but it did not change corticosterone secretion in obese animals. Mifepristone treatment decreased AVP mRNA levels in lean animals in the supraoptic nuclei, while in obese animals the AVP mRNA content was increased in the paraventricular nuclei. Mifepristone treatment significantly increased the concentration of AVP in the median eminence in lean rats and decreased it in obese animals. Mifepristone treatment did not change concentrations of AVP in the pituitary gland. In the second experiment, mifepristone was given for 4 days (10 mg/kg orally twice daily), and its effects on 24-hour food intake and plasma AVP concentrations were measured.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential hypothalamic arginine vasopressin response to glucocorticoid receptor antagonism in lean and obese Zucker rats. 140 82

This paper describes four cats with hyperadrenocorticism. Cat 1 showed polydipsia and polyphagia. Diabetes mellitus was initially diagnosed. As the animal appeared to be insulin resistant, pituitary and adrenocortical function tests were performed and the diagnosis of hyperadrenocorticism was made. Resistance to the high-dose dexamethasone suppression test was noticed in this cat. Pathological examination revealed a pituitary chromophobe adenoma. Cat 2 presented with diabetes mellitus, which was treated with insulin. The animal had a pendulous abdomen and its coat was in a poor condition. The low-dose dexamethasone suppression test demonstrated hyperadrenocorticism. Necropsy findings of pituitary tumour and hyperplasia of the adrenal cortex confirmed the diagnosis. Cat 3 showed clinical abnormalities indicative of hyperadrenocorticism, for instance, muscle weakness, alopecia, multiple abscesses. The diagnosis of hyperadrenocorticism was confirmed by the results of the lowe-dose dexamethasone suppression test. Pathological examination revealed an adrenocortical carcinoma. Cat 4 presented with polydipsia. The cause of this symptom was not found initially. One and a half years later additional symptoms, such as nephritis and polyphagia developed. Hyperadrenocorticism was diagnosed because of a palpable mass cranial to the left kidney. The diagnosis was confirmed by the results of the lowe-dose dexamethasone suppression test and the necropsy findings.
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PMID:Hyperadrenocorticism in four cats. 141 43

Contrary to normal rats, diabetic rats are known to develop marked hypercholesterolemia when fed a cholesterol-enriched diet. The triggering factor involved in this hyperresponse has not been identified. With the aim of clarifying the role of the intestinal acyl-CoA:cholesterol acyltransferase (ACAT), we studied the effects of a high fat diet and the changes of intestinal ACAT activity during the early development of streptozotocin-diabetes in rats. Feeding diabetic rats with a diet enriched in cholesterol and saturated fat produced an increase in plasma and in tissue cholesterol as early as 3 days after streptozotocin injection in the absence of hyperphagia. Under these experimental conditions, treatment with insulin or with the ACAT inhibitor CL-277082 significantly reduced the plasma cholesterol to levels measured in nondiabetic rats fed the same high fat diet. An increase in [14C]cholesterol in plasma very low density lipoprotein was observed after oral administration of labeled cholesterol to 3-day diabetic rats. In parallel experiments, the direct measurement of small intestine microsomal ACAT activity revealed an increase, averaging 288% in diabetic rats 3 days after diabetes induction. This change in ACAT activity occurred simultaneously with an increase in plasma glucagon and was normalized by insulin treatment. The induction of intestinal ACAT activity in diabetic rats, its modulation by insulin, and the hypocholesterolemic effects of insulin or CL-277082 treatment clearly indicate that ACAT activity plays a major role in the initiation of diabetes-associated hypercholesterolemia.
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PMID:Role of the intestinal acyl-CoA:cholesterol acyltransferase activity in the hyperresponse of diabetic rats to dietary cholesterol. 143 72

Untreated insulin-deficient diabetes causes hyperphagia and neuroendocrine disturbances that may be partly mediated by increased hypothalamic activity of neuropeptide Y (NPY), a potent central appetite stimulant. The metabolic signal that stimulates hypothalamic NPY is unknown. This study aimed to determine whether insulin deficiency or hyperglycemia was responsible. Regional hypothalamic NPY concentrations were compared in streptozocin-diabetic (STZ-D) rats rendered nearly normoglycemic by either insulin replacement or food restriction. Untreated STZ-D rats were hyperphagic and showed significantly increased (p less than 0.01) hypothalamic NPY concentrations in the arcuate nucleus and lateral hypothalamic area. Once-daily ultralente insulin injections corrected hypoinsulinemia and hyperglycemia, abolished hyperphagia, and normalized NPY concentrations in all hypothalamic regions. By contrast, food restriction effectively lowered glycemia without raising insulin levels. In these underfed diabetic rats, NPY concentrations rose further and were significantly higher than nondiabetic and untreated diabetic levels in most hypothalamic regions. We conclude that insulin deficiency is a major stimulus to hypothalamic NPY in STZ-D, whereas hyperglycemia may exert an inhibitory influence. These findings support the hypothesis that hypothalamic NPY responds to specific metabolic cues and is involved in regulating energy balance and conserving body weight.
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PMID:Insulin deficiency is a specific stimulus to hypothalamic neuropeptide Y: a comparison of the effects of insulin replacement and food restriction in streptozocin-diabetic rats. 143 14

A high fat (HF) diet is known to induce obesity, but susceptibility to obesity induced by a HF diet differs not only among different strains of rats but also within the same strain. The present study revealed that the Lee index (an index of obesity) positively correlated with insulin, and inversely correlated with both the mitochondrial oxygen consumption in interscapular brown adipose tissue (BAT) and the resting metabolic rate (RMR) in Sprague-Dawley rats. This suggests the contribution of BAT thermogenesis and RMR, in addition to hyperphagia, to the intrastrain variation in susceptibility to HF diet-induced obesity.
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PMID:Brown adipose tissue thermogenesis and metabolic rate contribute to the variation in obesity among rats fed a high fat diet. 147 84

Although environmental factors are important triggers of non-insulin-dependent diabetes mellitus (NIDDM), heredity plays a major role in the pathogenesis of the disease. Insulin resistance manifested as impaired activation of glycogen synthase and thereby storage of glucose as glycogen in skeletal muscle is demonstrable early on in NIDDM relatives, suggesting that NIDDM could be an inherited muscle disease. On the other hand, insulin deficiency is almost unequivocally present before manifest diabetes develops. An intensive search for candidate genes for NIDDM has been initiated; so far it has not been possible to ascribe NIDDM to any alterations in the human genome. Given the heterogenous nature of NIDDM, its age-dependent penetrance and strong influence of environmental factors, it may not be fruitful to use NIDDM as an end-point in genetic linkage or association studies. It is more likely that DNA defects result in either insulin resistance or insulin deficiency, which in turn, can both lead to NIDDM. In accordance with the thrifty gene hypothesis, the insulin resistance gene has protected individuals during long periods of starving by storing energy as fat rather than as glycogen in muscle. The abundance of food in Western society has made this once protective gene a deleterious one, suggesting that these individuals are not equipped with the metabolic machinery to handle overeating.
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PMID:The etiology and pathogenesis of non-insulin-dependent diabetes. 148 43

Vanadyl sulfate trihydrate was given by gavage to streptozotocin-induced diabetic rats for 21 days at doses of 0, 25, 50, or 75 mg/kg/day. In marked contrast to the reduction in plasma glucose observed in diabetic animals given vanadyl sulfate via drinking water, diabetic rats given vanadyl by gavage were not characterized by normoglycemia. Similarly, in contrast to the normalizing effect of vanadyl in drinking water, vanadyl by gavage had only a minimal influence on diabetes associated hyperphagia and polydipsia. Despite the lack of marked effect of vanadyl by gavage on the above parameters, tissue vanadium accumulation in the gavaged rats was similar to that reported for rats given vanadium by drinking water. The present results (taken together with previous data) show that the administration of vanadium by gavage is not a viable alternative to the use of insulin in diabetes treatment.
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PMID:Administration of vanadyl sulfate by gavage does not normalize blood glucose levels in streptozotocin-induced diabetic rats. 150 5

Opiate antagonist inhibition of deprivation-induced intake and 2-deoxy-D-glucose (2DG) hyperphagia is significantly enhanced by the 5-hydroxytryptamine3 (5-HT3) antagonist, ICS-205,930. Interactions between opiate antagonists and either 5-HT or 5-HT2 antagonists produced smaller effects. The present study evaluated whether insulin (5 U/kg) hyperphagia was affected by methysergide (0.5-5 mg/kg), ritanserin (0.25-2.5 mg/kg), and ICS-205,930 (0.5-5 mg/kg) alone or in combination with naltrexone (2.5-10 mg/kg). Whereas ICS-205,930 stimulated insulin hyperphagia across the 6-h time course, ritanserin and, to a lesser degree, methysergide reduced insulin hyperphagia. Naltrexone marginally (19-33%) reduced insulin hyperphagia. Pairing naltrexone with either ICS-205,930 or ritanserin significantly suppressed insulin hyperphagia after 2 h. Pairing naltrexone with each of the serotonin antagonists significantly enhanced insulin hyperphagia after 4 and 6 h. These data suggest that 5-HT2 and 5-HT3 receptor subtypes interact with opioid systems to modulate insulin hyperphagia. Given that central insulin reduces food intake and body weight, the interaction between serotonergic and opioid systems may occur peripherally.
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PMID:Naltrexone, serotonin receptor subtype antagonists, and glucoprivic intake: 2. Insulin. 151 48

Elevated levels of immunoreactive hypothalamic neuropeptide Y have recently been reported both in streptozotocin-induced diabetic rats and in the spontaneously diabetic BB rat. We have measured the levels of neuropeptide Y encoding messenger ribonucleic acid (mRNA) in both of these rat models to determine whether an increase in neuropeptide Y gene expression is a contributory factor to the increases in hypothalamic neuropeptide Y immunoreactive peptide content. In the hypothalami of both the spontaneously diabetic BB/E and the streptozotocin-diabetic animals, neuropeptide Y mRNA showed significant elevations (to 204 +/- 13% (+/- SE) and 387 +/- 48% of control values, respectively, p less than 0.01 for both). Our results demonstrate that two models of insulin-deficient diabetes in the rat are associated with increased hypothalamic neuropeptide Y mRNA. Taken with the known effects of neuropeptide Y on food intake these results suggest that increased neuropeptide Y synthesis in the hypothalamus may be related to the hyperphagia seen in the diabetic condition.
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PMID:Increased hypothalamic neuropeptide Y messenger RNA levels in two rat models of diabetes. 155 14

The regulation of energy metabolism in obesity may differ from normal condition in several respects. The synthesis of lipids may be enhanced due to a greater production of insulin, estrogens and cortisol and to a lack of dehydroepiandrosterone. Lipolysis is reduced in obese subjects by a decreased secretion of catecholamines, growth hormone, adipsin and cachectin. Inadequate intake of food and stress modify the T3/rT3 ratio. Oxidative phosphorylation and the production of ATP is modified, thermogenesis decreases due to a reduced synthesis of thermogenin. A decreased activity of substrate cycles and of the Na-K ATPase, is expected. Most of these disorders are normalized in post-obese patients. Many common drugs interfere with energy metabolism, namely those used in psychiatry and all hormones and their antagonists mentioned above and used for a long time. Obesity should not be considered as a simple result of overeating and lack of physical activity.
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PMID:[Energy metabolism in obesity]. 158 28


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