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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Elemental chromium (Cr) is an essential micronutrient. It is required for optimal insulin activity and normal carbohydrate and lipid metabolism. Tri-valent chromium (Cr3+) is recommended for the treatment of diabetes and obesity. There is evidence that Cr3+ may have antidepressant properties, possibly by enhancement of monoamine function through its ability to increase amino acid transport to the brain. The aim of the present study was to investigate further the possible effects of Cr3+ treatment on peripheral amino acid availability and brain monoamine function in the rat. We undertook three studies in rats. The first was a time-course study in which animals were administered single doses of 50 mg/kg of Cr3+ picolinate and the second a dose-response study in which animals were given either 20 or 50 mg/kg Cr3+ picolinate versus vehicle alone via the intra-peritoneal route. In the third, animals were fed a diet containing Cr3+ picolinate (100 mg/kg) or a similar control diet for two weeks and were then sacrificed. Blood was sampled and brains were removed for later analysis. Results from the Cr3+ time-course study defined an optimal time for sampling of two hours after dosing. Results from the second study showed dose-related responses to Cr3+ treatment for a number of measured biochemical parameters including serum corticosterone. In the sub-chronic treatment study Cr3+ significantly increased serum free tryptophan (TRP), non-esterified free fatty acids (NEFFAs), corticosterone, together with brain TRP, serotonin (5-hydroxytryptamine, 5-HT), noradrenaline (NA) and pineal melatonin. From other studies in our laboratory we have shown that Cr3+ treatment can modify brain 5-HT function, perhaps by altering the sensitivity of central 5-HT2A receptors. The peripheral effect of Cr3+ picolinate treatments and their consequential central effect on increased serotonergic and noradrenergic function may suggest that Cr3+ could have some antidepressant-like actions. Future studies to confirm this are to be done.
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PMID:Effects of treatment with chromium picolinate on peripheral amino acid availability and brain monoamine function in the rat. 1535 78

Current evidence indicates that virtually all neuropsychiatric disorders, like many other common medical disorders, are genetically complex, with combined influences from multiple interacting genes, as well as from the environment. However, additive or epistatic gene interactions have proved quite difficult to detect and evaluate in human studies. Mouse phenotypes, including behaviors and drug responses, can provide relevant models for human disorders. Studies of gene-gene interactions in mice could thus help efforts to understand the molecular genetic bases of complex human disorders. The serotonin transporter (SERT, 5-HTT, SLC6A4) provides a relevant model for studying such interactions for several reasons: human variants in SERT have been associated with several neuropsychiatric and other medical disorders and quantitative traits; SERT blockers are effective treatments for a number of neuropsychiatric disorders; there is a good initial understanding of the phenotypic features of heterozygous and homozygous SERT knockout mice; and there is an expanding understanding of the interactions between variations in SERT expression and variations in the expression of a number of other genes of interest for neuropsychiatry and neuropharmacology. This paper provides examples of experimentally-obtained interactions between quantitative variations in SERT gene expression and variations in the expression of five other mouse genes: DAT, NET, MAOA, 5-HT(1B) and BDNF. In humans, all six of these genes possess polymorphisms that have been independently investigated as candidates for neuropsychiatric and other disorders in a total of > 500 reports. In the experimental studies in mice reviewed here, gene-gene interactions resulted in either synergistic, antagonistic (including 'rescue' or 'complementation') or more complex, quantitative alterations. These were identified in comparisons of the behavioral, physiological and neurochemical phenotypes of wildtype mice vs. mice with single allele or single gene targeted disruptions and mice with partial or complete disruptions of multiple genes. Several of the descriptive phenotypes could be best understood on the basis of intermediate, quantitative alterations such as brain serotonin differences. We discuss the ways in which these interactions could provide models for studies of gene-gene interactions in complex human neuropsychiatric and other disorders to which SERT may contribute, including developmental disorders, obesity, polysubstance abuse and others.
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PMID:Experimental gene interaction studies with SERT mutant mice as models for human polygenic and epistatic traits and disorders. 1465 7

Dexfenfluramine, a drug formerly prescribed for treatment of obesity, caused heart valve damage and pulmonary hypertension in some people. The cause of the toxicity has not been defined, but 5-HT has been implicated. The objective of this study was to evaluate the effect of the anorectic agent, d-fenfluramine, and its major metabolite, d-norfenfluramine, on intact human platelet serotonin (5-HT) transport in vitro. The effects of d-fenfluramine and d-norfenfluramine on platelet uptake and efflux of 3H-5-HT were measured in buffer at pH 6.7, to optimize serotonin transporter (SERT) function, and at pH 7.4. Uptake of 3H-5-HT at pH 6.7 and 7.4 was inhibited by both agents at micro m concentrations (IC50, d-fenfluramine approximately 3 microM; d-norfenfluramine approximately 10 microM). However, no efflux of 3H-5-HT from labeled platelets at either pH 6.7 or 7.4 occurred at similar concentrations of d-fenfluramine or d-norfenfluramine. With inhibition of platelet dense granule 3H-5-HT uptake by reserpine, efflux of 3H-5-HT was observed at pH 6, but not at pH 7.4. Fluoxetine, a SERT inhibitor, was a more potent inhibitor of uptake (IC50 0.05 microM) than d-fenfluramine, but the anorectic agent, phentermine, had no effect. Therefore, d-fenfluramine and d-norfenfluramine inhibit human platelet uptake of 5-HT in vitro at tissue concentrations attainable in vivo, but they do not stimulate 5-HT efflux due to dense granule sequestration. Inhibition of platelet 5-HT uptake may play a role in the cardiopulmonary toxicity of d-fenfluramine, but other factors probably contribute, since similar toxicity has not been observed with fluoxetine.
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PMID:The effect of the anorectic agent, d-fenfluramine, and its primary metabolite, d-norfenfluramine, on intact human platelet serotonin uptake and efflux. 1467 3

The serotonin 5-HT(2C) receptor (HTR2C) helps regulate appetite and body weight. An HTR2C promoter polymorphism (-759C/T) has been associated with obesity and with weight gain in response to antipsychotic (neuroleptic) drugs. We studied this polymorphism in 120 obese women (BMI > or = 30) and 104 non-obese (BMI < or = 25) women. The C allele was commoner in the obese group (OR = 1.72 [95% CI, 1.13-2.64], P = 0.008). Ninety-five of the obese women participated in a randomized trial of psychological treatments for weight loss. Among these women, heterozygotes lost less weight during the trial than did homozygotes (6.8 vs. 9.7 kg; P = 0.047) and weighed more 6 months (90.1 vs. 83.6 kg; P = 0.006) and 12 months (91.8 vs. 84.6 kg; P = 0.009) later. Heterozygotes also had higher triglyceride levels than homozygotes. C/C subjects in the obesity trial did not differ from T/T subjects in terms of weight loss or triglycerides. In a separate RT-PCR study of 43 subjects, we found that HTR2C mRNA abundance in frontal cortex was unaffected by -759C/T status. Our data extend the evidence that HTR2C promoter variation may be a risk factor for obesity and, perhaps through heterosis, influences weight loss by obese women. Pharmacogenetic testing of HTR2C promoter variants may be valuable when evaluating anti-obesity drugs which act directly or indirectly on the receptor.
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PMID:A 5-HT2C receptor promoter polymorphism (HTR2C - 759C/T) is associated with obesity in women, and with resistance to weight loss in heterozygotes. 1504 62

Binge eating disorder (BED) is a newly defined diagnostic category characterized by recurrent episodes of binge eating not followed by the inappropriate compensatory weight loss behaviors characteristic of bulimia nervosa. BED is usually associated with overweight or obesity and psychopathology. Pharmacotherapy may be a useful component of a multidimensional treatment approach. Although pharmacotherapy research in BED is still in its preliminary stages. some drugs have been shown to be promising agents. This paper reviews available pharmacological treatment studies of BED and related conditions. Currently, three main classes of drugs have been studied in double-blind, placebo controlled trials in BED: antidepressants, anti-obesity agents, and anticonvulsants. Serotonin selective reuptake inhibitors (SSRIs) are the best studied medications. Thus, fluoxetine, fluvoxamine, sertraline and citalopram have been shown to modestly but significantly reduce binge eating frequency and body weight in BED over the short term. More recently, the anti-obesity agent sibutramine and the anticonvulsant topiramate have been shown to significantly reduce binge eating behavior and body weight in BED associated with obesity. Special issues concerning current pharmacological trials and future research directions in this area are also discussed.
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PMID:Pharmacological approaches in the treatment of binge eating disorder. 1505 14

A series of 1-(1-indolinyl)-2-propylamines was synthesised and evaluated as 5-HT(2C) receptor agonists for the treatment of obesity. The general methods of synthesis of the precursor indoles are described. The functional efficacy and radioligand binding data for all of the compounds at 5-HT(2) receptor subtypes are reported. A number of compounds were found to reduce food intake in rats after oral administration.
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PMID:Indoline derivatives as 5-HT(2C) receptor agonists. 1508 Oct 42

It was first established in the 1970s that the brain serotonin (5-HT) system was involved in the control of eating. Subsequent progress in the molecular pharmacology of 5-HT receptors, and the development of selective 5-HT receptor ligands, has clarified our understanding of the role of 5-HT in the regulation of ingestive behavior. Of the 14 5-HT receptor subtypes currently described, 5-HT1A, 5-HT1B and 5-HT2C receptors have been of principal interest in the regulation of food intake. This is largely due to the development of suitable agonists, antagonists and gene-knockout animals with which the role of these receptors can be elucidated. The recent development of selective ligands and knockout mice for other 5-HT receptors, including the 5-HT2B and 5-HT6 receptors, has also suggested a role for these receptor subtypes in eating behavior. Studies using such approaches should further our understanding of the role of serotonin in the regulation of feeding behavior and thus, may lead to the development of novel, safe, serotonin receptor ligands for the treatment of obesity.
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PMID:Serotonin receptor ligands and the treatment of obesity. 1513 78

Obesity is a major public health problem, which occurs in epidemic proportions. Our understanding of the systems of the brain related to energy balance has increased over the last decade. As a result, drugs most commonly used today in the management of obesity have their primary effect in modulating the balance between monoaminergic neurotransmitters, among other serotonin. Serotonin is believed to be involved in the complex process of integrating physiological and behavioral systems geared towards energy balance. However, gradual weight gain seen in most people suggests that the regulatory system may not be sufficient under all circumstances. An insufficient serotoninergic neuronal function in the central nervous system has been shown in many studies to occur in patents with depression. In such serotonin-deficient patients, treatment with drugs increasing the concentration of serotonin at serotoninergic synapses gives a favorable clinical response. Taken together, this suggests to a certain extent a common pathophysiology between obesity and depression. Literature spanning several decades has addressed the relationship among obesity and depression. However, obesity and depression research have evolved as two independent disciplines, which rarely or never overlap. In this paper, we propose the notion that obesity and depression may represent different manifestations of the same disease process - Janus faces of the modern society.
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PMID:Obesity and depression: same disease, different names? 1548 71

The present study examined the levels of 5-HT(2A) and 5-HT(2C) (2A and 2C receptors of 5-hydroxytryptamine; serotonin) receptor messenger RNA (mRNA) expressions in the brain of chronic high-fat diet-induced obese (DIO) and obese-resistant (DR) mice. Thirty-one mice were used in this study. Twenty-four mice were fed with a high-fat diet (HF: 40% of calories from fat) for 4 weeks and then classified as the DIO (n = 8) or DR (n = 8) mice according to the highest and lowest body weight (BW) gainers. Seven mice were placed on a low-fat diet (LF: 10% of calories from fat) and were used as controls. After 20 weeks of feeding, the visceral fat accumulation was 620 +/- 42 mg in the DIO group versus 198 +/- 89 mg in the DR and 84 +/- 18 mg in the LF groups. Using quantitative in situ hybridization techniques, levels of 2A and 2C serotonin (5-HT) receptor mRNAs were measured in multiple brain sections of mice from the three groups. Most regions did not differ between groups but, importantly, the DIO mice had a significantly higher level of 5-HT(2A) receptor mRNA expression in the olfactory nucleus (Olf) compared to the DR and LF mice (+30% and +37%, respectively). The levels of Olf 5-HT(2A) receptor mRNA expression were related to body fat mass. The level of 5-HT(2C) mRNA receptor expression in the ventromedial hypothalamic (VMH) nucleus was 40% higher in the DIO mice than in the LF mice. Furthermore, the 5-HT(2C) receptor mRNA expression in the posterodorsal part of the medial amygdaloid (MePD) nucleus was 25% higher in the DIO mice than in the DR mice. The level of VMH 5-HT(2C) receptor mRNA expression was correlated with body fat mass. In conclusion, this study has demonstrated differentially regulated levels of the 5-HT(2A) and 5-HT(2C) receptor mRNA expressions in the specific brain regions of the DIO and DR mice. It provides neural anatomical bases that the 5-HT(2C) receptors positively influence satiety center (VMH) while the 5-HT(2A) receptor regulates olfactory sensory effects. The findings also assist us to understand the role of these receptors in mice susceptible or resistant to diet-induced obesity.
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PMID:Differential expression of 5-HT(2A) and 5-HT(2C) receptor mRNAs in mice prone, or resistant, to chronic high-fat diet-induced obesity. 1530 19

The Society for Medicines Research organized a one-day meeting on antiobesity drugs on March 26, 1998, in London. Current environmental risks for obesity include an increase in the proportion of fat consumption--especially an increase in the fat-to-carbohydrate ratio--and an increase in a sedentary life-style without an appropriate lowering in food intake. Energy balance plays a pivotal role of in the control of body stores. Knowing the mechanisms of the control of energy intake and energy expenditure provides explanations for the incidence of obesity and also possible sites for drug intervention. The genetic basis for obesity is complex, with the probability of a number of interacting genes being involved (polygenic inheritance). Each of the main components of the energy balance relationship has a distinct genetic basis. The ob gene was first identified in 1994 by Friedman, and its product is leptin, which may well be a potential target for obesity treatment. Speakers at the meeting highlighted various targets that hold promise in developing pharmacological treatments for obesity: increasing the activity of satiety factors (CCK-8, GPL-1, ACTH, alphaMSH and 5-HT acting on 5-HT(2C) receptors); inhibiting orexigenic agents (NPY, MCH, galanin); targeting thermogenesis (beta(3)-adrenergic agonists and uncoupling proteins); targeting fat absorption; and targeting neuropeptides. Some of the compounds developed to act on these sites are now becoming available.
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PMID:Update on antiobesity drugs. 1561 66


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