Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To clarify whether nicotine stimulates the sympathetic nervous system (SNS) and thermogenesis in brown adipose tissue (BAT) and whether it promotes the resting metabolic rate (RMR), with resulting mitigation of obesity, we measured norepinephrine (NE) turnover (an indicator of SNS activity), guanosine-5'-diphosphate (GDP) binding (a thermogenic indicator), oxygen consumption in BAT, and RMR in monosodium-L-glutamate (MSG) obese and saline control mice after 2 weeks treatment with nicotine. Nicotine significantly increased NE turnover, GDP binding, oxygen consumption in BAT, and RMR, and significantly reduced body weight in MSG obese mice as well as in control mice without affecting food intake. These results suggest that nicotine stimulates NE turnover and thermogenesis in BAT, and promotes RMR, all of which contribute to the mitigation of obesity.
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PMID:Effect of nicotine on norepinephrine turnover and thermogenesis in brown adipose tissue and metabolic rate in MSG obese mice. 238 96

Neonatal male rats were treated with monosodium glutamate (MSG) at either 2 or 4 mg/g BW on alternate days during the first 10 days of life. As adults, the 4 mg MSG-treated rats displayed the obesity, growth retardation, and reduced pituitary weights that typify this syndrome. These animals had no detectable plasma GH as determined from serial blood samples taken every 20 min for 8 consecutive h. Associated with this loss of circulating GH was an induction of the female-specific hepatic cytochrome P450 2d (gene IIC12) and the disappearance of the male-specific form of cytochrome P450 2c (gene IIC11). The catalytic activities of cytochrome P450 2c (i.e. androgen 16 alpha- and 2 alpha-hydroxylase), sex-dependent hexobarbital hydroxylase and total cytochrome P450 were similarly feminized. Rats exposed to the 2-mg dose of MSG were also obese, but their growth rates and pituitary sizes were not as severely affected as in the 4 mg MSG-treated rats. Circulating GH in these lower dosed males was secreted in a pulsatile pattern similar to that in normal males, except that the pulse amplitude was reduced as much as 90%. In spite of this profound decline in GH peak heights in the 2 mg MSG-treated males, liver metabolism was characteristically masculine. That is, female-specific cytochrome P450 2d remained undetectable, while the male forms of cytochrome P450 2c, 2a (gene IIIA2), and RLM2 (gene IIA2), their respective catalytic steroid hydroxylase activities, and associated sex-dependent drug-metabolizing enzymes were expressed at the level of or greater than that in normal males. Thus, while an ultradian pulse of circulating GH is necessary for the characteristically masculine profile of sex-specific forms of hepatic cytochrome P450, neither the amplitude of the secretory peaks nor their total GH content is critical, and these can be greatly reduced from the normal male levels.
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PMID:Signalling elements in the ultradian rhythm of circulating growth hormone regulating expression of sex-dependent forms of hepatic cytochrome P450. 251 Sep 88

To clarify whether cigarette smoke stimulates the sympathetic nervous system (SNS) and thermogenesis in interscapular brown adipose tissue (IBAT), we measured norepinephrine (NE) turnover, an indicator of SNS activity, guanosine-5'-diphosphate (GDP) binding, a thermogenic indicator, and oxygen consumption in IBAT in monosodium-L-glutamate (MSG)-induced obese and saline control mice following a two-week exposure to cigarette smoke. Cigarette smoke significantly increased NE turnover, GDP binding and oxygen consumption in IBAT, and significantly reduced body weight in MSG obese mice as well as in control mice. However, food intake was unchanged in the MSG group. These results suggest that cigarette smoke stimulates NE turnover and thermogenesis in BAT, which contribute to the mitigation of obesity.
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PMID:Effects of cigarette smoke on norepinephrine turnover and thermogenesis in brown adipose tissue in MSG-induced obese mice. 258 62

Whole brain concentrations of 3-hydroxybutyrate, glutamate and gamma-aminobutyric acid (GABA) have been measured in two strains of rats with differing susceptibility to obesity. S 5B/Pl rats are resistant to developing obesity when eating a high-fat diet, whereas Osborne-Mendel rats readily develop obesity when eating the same diet. We tested the hypotheses that brain 3-hydroxybutyrate, glutamate and GABA differ between S 5B/Pl rats and Osborne-Mendel rats, and that these substrates/neuroregulators are altered when eating a high-fat diet primarily in S 5B/Pl (resistant) rats. Blood and brain 3-hydroxybutyrate concentrations were higher in S 5B/Pl rats than in Osborne-Mendel rats (p less than 0.05) but diet effects were not significant. Brain glutamate concentration, like 3-hydroxybutyrate, was higher in S 5B/Pl rats than in Osborne-Mendel rats (p less than 0.01) and was not affected by adding fat to the diet. Brain GABA differed only slightly between strains but increased after adding fat to the diet (p less than 0.05) in both strains with a greater increase occurring in S 5B/Pl rats. The brains of S 5B/Pl rats are chronically exposed to higher levels of 3-hydroxybutyrate and glutamate than are those of Osborne-Mendel rats. Thus, 3-hydroxybutyrate is a potential signal in the regulation of body weight. Brain GABA increases with fat feeding, especially in S 5B/Pl rats, suggesting that the ability to adjust to an energy dense diet may be through suppression of food intake by elevated brain GABA.
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PMID:Brain 3-hydroxybutyrate, glutamate, and GABA in a rat model of dietary obesity. 266 5

Injections of monosodium glutamate to neonate rats induce chronic growth hormone deficiency by hypothalamic lesions in the regions of the nucleus arcuatus and the eminentia mediana. The glutamate treated rats develop massive obesity. By this type of obesity hyperinsulinemia in the dynamic phase is not evident. The adipose tissue of the GOR (glutamate obese rat) is characterized by hypertrophic adipocytes and diminished number of adipocytes. In the GOR glucose oxidation and glucose lipid conversion are increased, but insulin sensitivity of glucose metabolism is diminished. The enhanced glucose utilization in adipose tissue of the GOR is discussed as being the consequence of the chronic growth hormone deficiency.
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PMID:[Glucose utilization in adipose tissue of rats in chronic somatotropin deficiency]. 267 26

Adipsin is a serine protease that is secreted by adipocytes into the bloodstream; it is deficient in several animal models of obesity, representing a striking example of defective gene expression in this disorder. Recombinant mouse adipsin was purified and its biochemical and enzymatic properties were studied in order to elucidate the function of this protein. Activated adipsin has little or no proteolytic activity toward most substrates but has the same activity as human complement factor D, cleaving complement factor B when it is complexed with activated complement component C3. Like authentic factor D, adipsin can activate the alternative pathway of complement, resulting in red blood cell lysis. Decreased (58 to 80 percent) complement factor D activity, relative to lean controls, was observed as a common feature of several experimental models of obesity, including the ob/ob, db/db, and monosodium glutamate (MSG)-injected mouse and the fa/fa rat. These results suggest that adipsin and the alternative pathway of complement may play an unexpected but important role in the regulation of systemic energy balance in vivo.
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PMID:Adipsin and complement factor D activity: an immune-related defect in obesity. 273 15

Mice treated with monosodium glutamate (MSG) in the neonatal period grow into obese, stunted adults without overeating. We have previously demonstrated normal control of brown adipose tissue (BAT) thermogenic function in the MSG-treated mouse and have concluded that thermoregulation at a lower than normal body temperature for most of the time is a major cause of its obesity. The objective of the present experiments was to find out whether adrenalectomy would prevent obesity in the MSG-treated mouse, as it does in hyperphagic obese rodents, and whether the thermoregulatory anomaly would be prevented by this procedure. MSG-treated mice that were adrenalectomized at 5 wk of age and studied at 10 wk of age did not become obese. Adrenalectomy increased body temperature of MSG-treated mice to normal (male mice) or almost normal (female mice). Adrenalectomy increased BAT mitochondrial guanosine 5'-diphosphate binding in MSG-treated mice, indicative of an increased thermogenic state, but had the same effect in control mice. We conclude that obesity in the MSG-treated mouse is secondary to the high level of corticosterone in its blood, which raises its metabolic efficiency, an effect of corticosterone also seen in normal lean mice, and causes it to thermoregulate at a low energy-conserving level. This latter effect is peculiar to the MSG-treated mouse and is not seen in corticosterone-treated normal mice.
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PMID:Adrenalectomy prevents obesity in glutamate-treated mice. 276 98

The mouse adipsin gene encodes a member of the serine protease family that is expressed predominantly in adipose tissue and is secreted into the bloodstream. Adipsin expression is sharply down-regulated in several models of genetic and acquired obesity, representing the first example of an adipocyte gene whose expression is greatly altered in this disorder. In this study, we have asked whether a DNA fragment from the adipsin gene can direct tissue-specific expression of a heterologous gene and mediate the suppression of this expression in genetic and chemically induced obesity. Transgenic mice have been constructed with 950 bases of DNA from the 5' flanking region of the adipsin gene linked to the bacterial chloramphenicol acetyltransferase (CAT) gene in a mouse strain bearing a recessive obesity gene (diabetes, db). By crossing db/+ transgenic mice with nontransgenic db/+ mice, we obtained progeny that allowed a direct comparison of CAT expression in the tissues of lean and obese littermates. The lean mice express CAT activity predominantly in adipose tissue, while the obese mice show a marked reduction in CAT expression relative to the lean controls. When similar experiments are performed with an adipsin-CAT fusion gene containing a heterologous AKV (AKR mouse leukemia virus) enhancer, the tissue specificity of CAT expression in lean mice is broadened to include the thymus, spleen, brain, and other tissues; down-regulation occurs in all of these tissues in mice homozygous for the obesity gene or in mice that have been injected with monosodium glutamate (MSG), which induces obesity. These results indicate that 950 bases of the 5' flanking region of the adipsin gene carry information that specifies both expression in adipose tissue and a response to a gene or chemical that induces obesity. These results also suggest that the trans-acting factors that are regulated aberrantly in these forms of obesity are not restricted to adipose tissue and could play a role in obesity-linked dysfunctions observed in other tissues as well.
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PMID:Obesity-linked regulation of the adipsin gene promoter in transgenic mice. 279 20

We have studied the regulation of adrenal function in male rats treated neonatally with monosodium glutamate (MSG) and in littermate controls. When 6-7 months old, MSG-treated rats presented reduced body, adrenal and pituitary weight, obesity, atrophy of the optic nerve and damage of the arcuate nuclei (ARN) of the hypothalamus. MSG-treated rats showed increased serum corticosterone (CORT) levels under resting conditions; after ether stress the increase in serum CORT was greater in MSG animals when compared to littermate controls. Plasma ACTH followed the same trend although it reached significance after ether stress only. Both circulating CORT and ACTH were normally suppressed by dexamethasone (DEX) administration. Levels of corticosteroid binding globulin were also increased, whereas daily circadian rhythm of serum CORT was blunted. We also determined cytosolic receptors in areas suggested to participate in the negative feedback of glucocorticoids at the central level. Binding of (3H)-DEX in MSG rats was similar to controls in hippocampus, whole hypothalamus and anterior pituitary, but a significant reduction (approximately equal to 50%) was obtained after microdissection in the area normally occupied by the ARN, without changes in the ventromedial nuclei of the hypothalamus. These results suggest that the ARN may be involved in the regulation of the pituitary-adrenal axis, although the abnormalities observed in the MSG syndrome partially differ from those in rats with hippocampal damage, previously studied in our laboratory.
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PMID:Regulation of the central nervous system-pituitary-adrenal axis in rats after neonatal treatment with monosodium glutamate. 285 47

Mice treated with glutamate in the neonatal period are known to develop into stunted obese adults, despite hypophagia. Our objective was to find out whether brown adipose tissue (BAT) thermogenic function might be abnormal in the glutamate-obese mouse. At 10 wk of age, group-housed glutamate-obese mice exhibited nocturnal and early diurnal torpor, i.e., they thermoregulated at a lower than normal body temperature. When exposed to 4 degrees C, they died in hypothermia within 24 h. They could adapt to living at 14 degrees C for up to 1 wk but failed to adjust their food intake sufficiently to maintain their body weight. Their fat stores were, nevertheless, conserved. BAT was present in increased amounts in glutamate-obese mice. Its thermogenic activity (as assessed by the level of mitochondrial GDP binding) was normal (male mice) or reduced (female mice). A normal thermogenic responsiveness of BAT to cold occurred. The thermogenic response of BAT to a cafeteria diet was normal (male mice) or reduced (female mice). Serum corticosterone concentration was increased in both male and female glutamate-treated mice particularly in the cold. We conclude that the high metabolic efficiency and obesity of the glutamate-obese mouse are principally a consequence of its maintenance of a hypothermic torpid state for more than 50% of the time. An additional deficit in energy expenditure in female, but not male, glutamate-obese mice is associated with suppressed responsiveness of the thermogenic function of BAT to diet and may account for the greater degree of obesity in female than in male glutamate-treated mice.
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PMID:Brown adipose tissue thermogenesis, torpor, and obesity of glutamate-treated mice. 287 42


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