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

This study shows the apparent role of the ventromedial nucleus of the hypothalamus (VMH) in regulating food intake in the goose. The feeding pattern of normal animals has been compared with that of animals made hyperphagic by destruction of the VMH. Lesioning of the VMH modified the circadian pattern of intake. All the geese tended to equalize their intakes between the light and dark periods. The overall effect of lesioning was considerable hyperphagia resulting from an increase in the number of meals and of their amplitude and duration, as well as in the rate of ingestion. We have emphasized the importance of defining the meal when interpreting changes in the correlations between the amount of food ingested during the meal and the length of pre or postprandial intervals after destruction of the VMH. Although it is important, the fatty liver syndrome induced after hyperphagia is not sufficient to produce fatty livers which can compete with those obtained by traditional cramming.
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PMID:[Role of the ventromedial nucleus of the hypothalamus in regulating feeding behavior in Landes geese]. 689 90

The effects of induced hypothalamic hyperphagia and forced-feeding were studied in 30 geese of the Landes breed. They were housed in individual cages under a dark-light cycle of 12 hrs light-12 hrs darkness. Eleven geese with ventromedian hypothalamic (VMH) lesions and 8 controls were fed ad libitum. A third lot of 11 force-fed animals was pair-fed with the operated geese. The study lasted 4 weeks after an adaptation period to the new environmental conditions. The daily food intake of the geese and their weekly liveweight gain were monitored. After VMH lesions, the mean food intake of the geese increased by 169 p. 100 so that after each treatment their liveweight increased and they became obese (P less than 0.001). The tissue distribution of the group with lesions showed a higher amount of subcutaneous fat (P less than 0.05), while the mesenteric fat (P less than 0.05) was more abundant after forced-feeding. The liver weight was much higher in all cases; its increment reached 311 p. 100 in geese with VMH lesions and 193 p. 100 in the force-fed. However, those values were too low when compared to the means obtained by traditional forced-feeding. Hyperphagia in the geese was very marked as compared to that in rats, but it was insufficient to produce a considerable hepatic steatosis.
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PMID:Effect of induced hypothalamic hyperphagia and forced-feeding on organ weight and tissular development in Landes geese. 696 79

We evaluated amount and composition of amino acids in supplementation of hyperalimentation from the standpoint of whether it may improve nutrition and/or reduce the indexes of uremia such as BUN. Rats with established uremia, by 5/6 nephrectomy, were treated with various isocaloric solutions containing different amount of essential amino acids and histidine (EAA) or standard amino acids (SAA) which were formulated to provide Cal/N ratios of 300, 600, and 900. The BUN was lower and the nutritional index was better in rats infused with EAA compared with those administrated SAA, while severe distortion of plasma amino acid concentration, hyperammonemia, and fatty liver were observed at the Cal/N 300 condition. Rats infused with SAA gained positive nitrogen balance at the condition of Cal/N 300; however, plasma amino acid distortion was still observed. These results indicate that administration of EAA alone for treatment of renal failure needs high-calorie and low-nitrogen conditions such as Cal/N 600 for avoiding complications. Administration of standard amino acid solution is safe and nutritionally effective in the Cal/N 300 condition, but there are a few problems concerning nitrogen availability and plasma amino acid pattern.
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PMID:Amino acid supplementation to hyperalimentation in uremic rats: effects of amount and composition of amino acids on nutrition and uremia. 804 60

The progression of alimentary fatty liver to liver cirrhosis is a very rare observation. During the year after surgical extirpation of a suprasellar craniopharyngioma in a seven years old boy developed severe obesity and again six years later at autopsy a complete liver cirrhosis with fatty liver was established. Injury of the ventromedial hypothalamic nuclei and resulting hyperphagia is the reason for the obesity following suprasellar tumours. The pathogenesis of liver cirrhosis following alimentary fatty liver is not completely evident up to now, such a progression is possible--as shown in this case--also in children and within a short period.
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PMID:[Development of complete liver cirrhosis in hyperphagia-induced fatty liver]. 815 10

In lipoatrophic diabetes, a lack of fat is associated with insulin resistance and hyperglycemia. This is in striking contrast to the usual association of diabetes with obesity. To understand the underlying mechanisms, we transplanted adipose tissue into A-ZIP/F-1 mice, which have a severe form of lipoatrophic diabetes. Transplantation of wild-type fat reversed the hyperglycemia, dramatically lowered insulin levels, and improved muscle insulin sensitivity, demonstrating that the diabetes in A-ZIP/F-1 mice is caused by the lack of adipose tissue. All aspects of the A-ZIP/F-1 phenotype including hyperphagia, hepatic steatosis, and somatomegaly were either partially or completely reversed. However, the improvement in triglyceride and FFA levels was modest. Donor fat taken from parametrial and subcutaneous sites was equally effective in reversing the phenotype. The beneficial effects of transplantation were dose dependent and required near-physiological amounts of transplanted fat. Transplantation of genetically modified fat into A-ZIP/F-1 mice is a new and powerful technique for studying adipose physiology and the metabolic and endocrine communication between adipose tissue and the rest of the body.
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PMID:Surgical implantation of adipose tissue reverses diabetes in lipoatrophic mice. 1067 52

Lipoatrophic diabetes is caused by a deficiency of adipose tissue and is characterized by severe insulin resistance, hypoleptinemia, and hyperphagia. The A-ZIP/F-1 mouse (A-ZIPTg/+) is a model of severe lipoatrophic diabetes and is insulin resistant, hypoleptinemic, hyperphagic, and shows severe hepatic steatosis. We have also produced transgenic "skinny" mice that have hepatic overexpression of leptin (LepTg/+) and no adipocyte triglyceride stores, and are hypophagic and show increased insulin sensitivity. To explore the pathophysiological and therapeutic roles of leptin in lipoatrophic diabetes, we crossed LepTg/+ and A-ZIPTg/+ mice, producing doubly transgenic mice (LepTg/+:A-ZIPTg/+) virtually lacking adipose tissue but having greatly elevated leptin levels. The LepTg/+:A-ZIPTg/+ mice were hypophagic and showed improved hepatic steatosis. Glucose and insulin tolerance tests revealed increased insulin sensitivity, comparable to LepTg/+ mice. These effects were stable over at least 6 months of age. Pair-feeding the A-ZIPTg/+ mice to the amount of food consumed by LepTg/+:A-ZIPTg/+ mice did not improve their insulin resistance, diabetes, or hepatic steatosis, demonstrating that the beneficial effects of leptin were not due to the decreased food intake. Continuous leptin administration that elevates plasma leptin concentrations to those of LepTg/+:A-ZIPTg/+ mice also effectively improved hepatic steatosis and the disorder of glucose and lipid metabolism in A-ZIP/F-1 mice. These data demonstrate that leptin can improve the insulin resistance and diabetes of a mouse model of severe lipoatrophic diabetes, suggesting that leptin may be therapeutically useful in the long-term treatment of lipoatrophic diabetes.
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PMID:Transgenic overexpression of leptin rescues insulin resistance and diabetes in a mouse model of lipoatrophic diabetes. 1137 46

Aromatase, the enzyme responsible for the conversion of androgens to estrogens, is present in the mouse gonads, brain, adipose tissue and bone. Depletion of endogenous estrogens in the aromatase deficient mouse (ArKO) caused by the targeted disruption of the Cyp19 gene resulted in an impairment of sexual behaviour and an age-dependent disruption of spermatogenesis. This disruption occurred during early spermiogenesis, due possibly to increased number of apoptotic round spermatids. Development of obesity was associated with ageing, decrease in lean mass, hypercholesterolemia, hyperleptinemia, and insulin resistance and hepatic steatosis. However, it was not correlated with hyperphagia but to decreased physically-active behaviour. ArKO mice also developed osteoporosis. Thus, studies using the ArKO mice model has led to several insights into the multiple roles played by estrogens in the development and maintenance of fertility, sexual behaviour, lipid metabolism and bone remodelling.
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PMID:Effect of estrogen deficiency in the male: the ArKO mouse model. 1216 Sep 96

The study population in this report by Lin et al. was ob/ob mice that have an inherited genetic deficiency of the appetite-suppressing hormone leptin. These mice develop hyperinsulinemia, insulin resistance, and fatty livers. Compared with their lean littermates and wild-type C57BL-6 mice, ob/ob mice have hepatomegaly. In this study, the authors compared three different groups of adult mice (aged 8-10 wk), including male ob/ob C57BL-6 mice, their lean littermates, and wild-type C57BL-6 mice of the same age and sex. The primary purpose of this study was to test the efficacy of metformin for treatment of fatty liver disease in obese, ob/ob mice that develop hyperinsulinemia or insulin resistance and fatty livers. Metformin therapy was found to eliminate fatty liver disease in this model. The potential mechanisms of the action of metformin were the inhibition of hepatic tumor necrosis factor (TNF)alpha and several TNF-inducible responses, which are likely to promote hepatic steatosis and necrosis. In these experiments, ob/ob mice were divided into three treatment groups. Group 1 consisted of eight mice that were treated with metformin and permitted to consume a nutritiously replete liquid mouse diet ad libitum. Mice in group 2 (n = 8) did not receive metformin but were pair-fed the same volume of liquid diet that the mice in the metformin-treated group had consumed on the previous day. Obese ob/ob mice in group 3 (n = 4) and lean mice received no metformin, as with the mice in group 2, but were permitted to consume the liquid diet ad libitum. Liquid diet was given to facilitate accurate daily comparison of food intake among the various treatment groups. All mice were weighed at the beginning of the study and weekly thereafter until killed and then sera, fat, and liver tissues were collected. Tissues were either fixed in buffered formalin and processed from the deceased mice for histology or snap frozen in liquid nitrogen and stored until RNA and proteins were isolated. The feeding protocol was repeated with a second group of 18 ob/ob mice. After 4 wk, hepatocytes were obtained by in situ liver perfusion with collagenase and assayed for cellular adenosine triphosphate (ATP) content. In each experiment, hepatocytes isolated from 3 mice from each treatment group were suspended in a medium and pooled for subsequent analysis to evaluate cell viability, determine the number of obtained cells, and to assay cellular ATP content. These experiments were repeated using another 3 mice from each treatment group, so that analysis of hepatocytes took place from six ob/ob mice in each feeding group.Hepatic steatosis was decreased significantly only in the metformin-treated group. The authors found that metformin's beneficial effect on the fatty liver disease of mice was not due to its ability to constrain hyperphagia, nor due to decreased caloric ingestion, because the daily caloric intakes of the metformin-treated mice and the pair-fed control mice were virtually identical. These caloric intakes were consistently approximately 20% less than that of another obese control group that was permitted to consume diet ad libitum. The authors also observed no significant effect of metformin on serum glucose concentration from fed, ob/ob mice. Metformin is known to reduce hyperinsulinemia by about 40% in both of these obese hyperinsulinemic and insulin-resistant rodent strains. In conclusion, Lin et al. documented that metformin improves fatty liver disease and reverses hepatomegaly, steatosis, and aminotransferase abnormalities in mice. In addition, the authors suggest that metformin might inhibit dieting-induced redistribution of lipid from the liver to adipose tissue depots. In summary, this study identifies a potential treatment for fatty liver disease in humans.
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PMID:Current biochemical studies of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis suggest a new therapeutic approach. 1449 93

Mutations in the melanocortin-4 receptor (MC4R) are associated with obesity. The obesity syndrome observed in humans with MC4R haploinsufficiency is similar to that observed in MC4R knockout mice, including increased longitudinal growth, hyperphagia, and fasting hyperinsulinemia. For comparison with other commonly investigated models of obesity and insulin resistance, we have backcrossed Mc4r-/- mice into the C57BL/6J (B6) background. Female obese Mc4r-/- mice exhibit reduced energy expenditure and an attenuated increase in fatty acid (FA) oxidation after exposure to high-fat diets compared with obese Lepob/Lepob mice. The reduced energy expenditure and FA oxidation correlates with changes in hepatic gene expression. The expression of genes involved in FA oxidation increased in obese Lepob/Lepob mice compared with wild-type and obese Mc4r-/- mice. In contrast, a key lipogenic enzyme, FA synthase (FAS), is increased in obese Mc4r-/- mice compared with obese Lepob/Lepob mice. Hyperinsulinemia, increased FAS mRNA expression and hepatic steatosis appear to be secondary to obesity in B6 Mc4r-/- mice. However, Mc4r-/- mice in a mixed genetic background develop severe hepatic steatosis at an early age. This might suggest an important role of the MC4R in regulating liver FA metabolism that is masked on the B6 background. Interestingly, the 10- to 20-fold increase in liver triglyceride in the outbred strain of Mc4r-/- mice is not always associated with fasting hyperinsulinemia or increased FAS mRNA expression. This observation suggests that changes in liver secondary to triglyceride accumulation lead to hyperinsulinemia and increased hepatic FAS expression in Mc4r-/- mice.
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PMID:Impaired coordination of nutrient intake and substrate oxidation in melanocortin-4 receptor knockout mice. 1455 Dec 22

The incidence of obesity has increased dramatically in recent years, making it one of the most pressing public health concerns worldwide. Obesity is commonly associated with comorbid conditions, most notably diabetes, coronary artery disease, and hypertension, and the coexistence of these diseases has been termed the Metabolic Syndrome. The identification of the hormone leptin provided a molecular link to obesity. Leptin is recognized as the central mediator in an endocrine circuit regulating energy homeostasis. Leptin administration leads to hypophagia, increased energy expenditure, and weight loss, while leptin deficiency enacts an adaptive response to starvation manifested by hyperphagia, decreased energy expenditure, and suppression of the neuroendocrine axis. While elucidation of leptin's role has permitted a more detailed view of the biology underlying energy homeostasis, most obese individuals are leptin resistant. A more complete understanding of the molecular components of the leptin pathway is necessary to develop effective treatment for obesity and the Metabolic Syndrome. The identification and role of one such component, stearoyl-CoA desaturase-1 (SCD-1), is reviewed here. Leptin's actions are not due to its anorectic effects alone. Leptin also mediates specific metabolic effects, including the potent depletion of triglyceride from liver and other peripheral tissues. To explore the molecular basis by which leptin depletes hepatic lipid, we used oligonucleotide arrays to identify genes in liver whose expression was modulated by leptin treatment. An algorithm was created that identified and ranked genes specifically repressed by leptin. The gene ranking at the top of this list was SCD-1, the rate limiting enzyme in the biosynthesis of monounsaturated fats. SCD-1 was specifically repressed during leptin-mediated weight loss, and mice lacking SCD-1 showed markedly reduced adiposity on both a lean and ob/ob background (ab(J)/ab(J); ob/ob), despite higher food intake. ab(J)/ab(J); ob/ob mice also showed a complete correction of the hypometabolic phenotype and hepatic steatosis of ob/ob mice, suggesting that fatty acid oxidation is enhanced in the absence of SCD-1. These findings indicate that pharmacologic manipulation of SCD-1 may be of benefit in the treatment of obesity, diabetes, hepatic steatosis, and other components of the Metabolic Syndrome.
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PMID:Stearoyl-CoA desaturase-1 and the metabolic syndrome. 1468 58


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