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

Obese individuals may be characterized by higher than normal basal and stimulated beta-endorphin plasma concentrations, which suggests an increased activity of the opioid system. This study was carried out to investigate whether the regulation of beta-endorphin secretion may be different in different phenotypes of obesity. Twenty-two obese women (body mass index greater than 30 kg/m2) without other endocrine and metabolic abnormalities were investigated. A group of seven normal weight healthy women matched for age served as controls. According to the protocol, obese women included in the study had a waist-to-hip ratio higher than 0.85 (n = 9) or lower than 0.80 (n = 13). The former were defined as having abdominal type and the latter peripheral type body fat distribution. Both groups were matched for body mass index. All women randomly underwent a corticotrophin-releasing hormone test (human CRF, 1 microgram/kg body weight) and a control saline study, with blood samples for beta-endorphin determination taken at regular intervals. Basal beta-endorphin levels were not significantly different between the three groups. No significant variation in the hormone levels occurred during the control study in either group. After CRF injection, however, beta-endorphin rose significantly in all women, but the hormone concentrations were significantly higher in obese women with abdominal fat distribution than in those with peripheral fat distribution and in controls. These results indicate that, among obese women, only those with the abdominal phenotype seem to have increased opioid activity.
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PMID:Beta-endorphin response to exogenous corticotrophin-releasing hormone in obese women with different patterns of body fat distribution. 824 28

The levels of immunoreactive corticotropin-releasing hormone (ir-CRH) were measured in discrete hypothalamic nuclei and the median eminence of obese Zucker rats and their lean littermates. More than 90% of total hypothalamic ir-CRH was detected in the median eminence in both obese and lean rats. Though ir-CRH levels in the paraventricular nucleus of obese rats tended to be lower than those of their lean littermates, no significant difference of ir-CRH levels was observed in any hypothalamic nuclei studied between obese and lean rats. However, ir-CRH levels in the median eminence of obese rats were significantly lower than those of their lean littermates (5263 +/- 438 pg/tissue vs. 7050 +/- 473 pg/tissue, P < 0.05). These results suggest that the hypoactive hypothalamic CRH tonus would play some role in the phenotypic expression of obesity in the genetically obese Zucker rats.
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PMID:Immunoreactive corticotropin-releasing hormone levels in discrete hypothalamic nuclei of genetically obese Zucker rats. 826 73

Feeding and its regulation by opioids were studied in lean sheep and sheep in the static phase of dietary obesity. Sheep were fasted 16 h and on separate days were injected IV with 0 (saline), 0.01, 0.1, 1, or 3 mg/kg naloxone 5 min before they were allowed ad lib intake for the ensuing 32 h. All sheep were in chronic zero energy balance when not fed ad lib during naloxone treatment. After 0 mg/kg naloxone, intake rate was at least twice as fast (p < 0.05) in lean than obese sheep through the first 4 h of ad lib feeding, but was similar (approximately 0.5 g/min) in both groups of sheep after 8 h of ad lib feeding. Dose-dependent inhibitory effects of naloxone on intake were observed in lean and obese sheep through the first 4 h of ad lib feeding with maximum inhibition at +2 h. Dose-response curve for naloxone inhibition of intake was shifted leftward in obese compared with lean sheep. Dose of naloxone needed to inhibit intake by 25% was less (p < 0.05) in obese (0.13 mg/kg) than lean (0.57 mg/kg) sheep when both groups experienced similar plasma concentrations of injected naloxone. Basal concentrations of immunoreactive beta-endorphin in fasted plasma were similar in lean (33 +/- 4 pg/ml) and obese (48 +/- 9 pg/ml) sheep. Dietary obesity in sheep was associated with reduced appetite and with enhanced responsiveness to the intake-inhibitory effects of naloxone.
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PMID:Feeding behavior and its responsiveness to naloxone differ in lean and obese sheep. 838 48

The presence of three regulatory peptides, corticotropin-releasing hormone, neuropeptide Y and endothelin-1, was studied by radioimmunoassay in the tumor tissue of an ACTH-secreting bronchial carcinoid. A 36-year-old female was admitted to hospital because of moon face, central obesity and hypertension. High levels of plasma ACTH and cortisol and urinary 17-OHCS and 17-KS were found. One mg dexamethasone did not suppress plasma ACTH and cortisol levels, but 8 mg did so slightly. Corticotropin-releasing hormone (100 micrograms, iv) stimulated plasma ACTH levels (0 min; 34.8 pmol/l; 30 min; 41.1 pmol/l). The computerized tomography showed the presence of a tumor in the right lung. This lung tumor was removed surgically and has been shown by microscopical examination to be a bronchial carcinoid with ACTH-positive cells. The tumor tissue concentrations of corticotropin-releasing hormone, neuropeptide Y and endothelin-1 were 3.34 pmol/g wet weight, 8.07 pmol/g wet weight and 0.92 pmol/g wet weight, respectively, although plasma concentrations of these three peptides were not elevated. Reverse phase high performance liquid chromatography showed that immunoreactive peptides in the tumor tissue were mainly eluted in the position of the standard peptides. These findings indicate that this case of ACTH-secreting bronchial carcinoid had high levels of corticotropin-releasing hormone, neuropeptide Y and endothelin-1 in its tumor tissue and suggested that these peptides may act locally, in a paracrine or autocrine manner, in the tumor.
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PMID:An ACTH-secreting bronchial carcinoid: presence of corticotropin-releasing hormone, neuropeptide Y and endothelin-1 in the tumor tissue. 838 6

Hyperandrogenism, insulin resistance, and obesity are common features of polycystic ovarian syndrome (PCOS). This study was designed to investigate the relationship among these factors and how they might contribute to ovulatory dysfunction in PCOS. Adrenal androgen secretion and insulin resistance were quantified in oligomenorrheic women with PCOS and in three groups of eumenorrheic women: weight-matched hirsute women, obese nonhirsute women, and thin nonhirsute women. Adrenal androgen secretion was defined as the androstenedione response to synthetic corticotropin. Insulin resistance was estimated by calculating the area under the curve for serum insulin levels in response to a 75 g oral glucose load. The mean serum androstenedione response (nmol/L) to corticotropin in PCOS (5.6 +/- 1.3) was greater than that in eumenorrheic hirsute women (3.4 +/- 0.5; P < 0.10), obese nonhirsute women (1.8 +/- 0.8; P < 0.05), and lean nonhirsute women (1.9 +/- 0.5; P < 0.05). The serum androstenedione response was not correlated with body mass index (BMI). The area under the curve for serum insulin (mU/L.min/1000) in PCOS (29.1 +/- 5.3) was greater (P < 0.001) than in eumenorrheic hirsute women (9.1 +/- 1.7), obese nonhirsute women (5.8 +/- 1.0), and lean nonhirsute women (4.5 +/- 0.4). The serum insulin response was highly correlated with BMI (P < 0.001) in the three groups of obese women, but women with PCOS became significantly more insulin resistant with increasing BMI (P < 0.02). There was no correlation between adrenal androgen secretion and insulin resistance in any of the groups. We conclude that adrenal hyperandrogenism and insulin resistance are independent predictors of anovulation in hirsute women. These conditions are present in both oligomenorrheic and eumenorrheic hirsute women, but are present to a greater extent in anovulatory women. Obese women with PCOS also differ from eumenorrheic controls by developing a greater degree of insulin resistance as body mass increases.
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PMID:The role of adrenal hyperandrogenism, insulin resistance, and obesity in the pathogenesis of polycystic ovarian syndrome. 838 5

We have studied pro-opiomelanocortin (POMC) gene expression by quantifying the POMC mRNA contents in anterior pituitaries of female Wistar fatty rats, a strain obtained by transfer of the fa gene in Zucker rat to Wistar Kyoto rat, in an attempt to understand the role of ACTH synthesis in altered ACTH and corticosterone secretion in these rats. Five- and 12-week-old female Wistar fatty rats and their lean littermates were examined. Plasma ACTH levels were significantly higher in fatty rats than in lean rats (5 weeks: 114.5 +/- 17.5 pg/ml vs. 54.3 +/- 12.4 pg/ml; 12 weeks: 83.8 +/- 12.3 pg/ml vs. 51.7 +/- 6.8 pg/ml; P < 0.01). There was no significant difference between 5-week-old fatty rats and lean rats in POMC mRNA contents nor in POMC/beta-actin ratios in anterior pituitaries. Twelve-week-old fatty rats, however, had significantly higher POMC mRNA contents and also higher POMC/beta-actin ratios in anterior pituitaries than those in lean littermates (P < 0.01, approximately three-fold difference between lean and obese rats). These data suggest that the difference in POMC mRNA contents between lean and obese rats becomes apparent as they grow and develop obesity and the elevated POMC mRNA levels are at least partly responsible for the increased ACTH secretion in 12-week-old fatty rats.
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PMID:Pro-opiomelanocortin messenger RNA levels in anterior pituitaries of female Wistar fatty rats. 839 99

Neuropeptide Y (NPY) is a 36 amino-acid peptide. It is localized within the brain but is also present peripherally. It is a well substantiated orexigenic peptide with several other endocrine and behavioural effects. In this study NPY mRNA levels were measured, using the polymerase chain reaction amplification technique, in the hypothalamus of pre-obese (unweaned 13-day-old), young (weaned 28-day-old) and adult (11-week-old) obese fa/fa rats and compared to those of lean age-matched controls. Before weaning, pre-obese pups had the same NPY mRNA levels as controls. After weaning NPY mRNA levels were increased 2-fold in young 28-day-old and 4-fold in adult obese rats, relative to corresponding controls. When adult obese rats were intracerebroventricularly-treated with ovine corticotropin-releasing hormone (oCRF) for 7 days, they stopped gaining body weight relative to vehicle-infused obese controls. Upon measuring NPY mRNA levels in the hypothalamus of these two groups of animals, it was shown that the high NPY mRNA levels of vehicle-treated (control) obese rats were decreased by 3-fold following the intracerebroventricular oCRF administration. It is proposed that: 1) hypothalamic NPY may play a role in the establishment and maintenance of the genetic obesity syndrome of the fa/fa rat, and 2) maintenance of the genetic obesity syndrome of the fa/fa rat, and 2) hypothalamic NPY could be partly regulated by central CRF.
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PMID:Hypothalamic neuropeptide Y messenger ribonucleic acid levels in pre-obese and genetically obese (fa/fa) rats; potential regulation thereof by corticotropin-releasing factor. 840 61

Knowledge of the effects of exercise in the regulation of energy balance is imperative for the assessment of the value (or limit) of exercise as a therapeutic adjunct in the treatment of obesity. This short review addresses the effects of exercise on the neurobiological control of food intake and energy expenditure. It has been proposed that exercise may affect the regulation of energy balance through the stimulation of corticotropin-releasing hormone (CRH) and neuropeptide Y (NPY). It is likely that the CRH and NPY neuropeptidergic systems exert some degree of control on food intake and energy expenditure. The increase in the CRHergic activity induced by moderately intense exercise would potentiate the effects of muscular activity in reducing energy stores by decreasing energy intake and increasing thermogenesis. Reduced food intake and increased thermogenesis are two of the more recognized biological actions of CRH. Exercise would also contribute to the stimulation of brain NPY neurons by reducing energy stores and plasma insulin levels. By producing orexigenic effects and reducing thermogenesis, activation of the NPY system would tend to oppose the physiological effects of CRH and therefore cancel out the effects of exercise on energy loss.
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PMID:Exercise and the neurobiological control of food intake and energy expenditure. 858 Nov

Correction of the obese state induced by genetic leptin deficiency reduces elevated levels of both blood glucose and hypothalamic neuropeptide Y (NPY) mRNA in ob/ob mice. To determine whether these responses are due to a specific action of leptin or to the reversal of the obese state, we investigated the specificity of the effect of systemic leptin administration to ob/ob mice (n = 8) on levels of plasma glucose and insulin and on hypothalamic expression of NPY mRNA. Saline-treated controls were either fed ad libitum (n = 8) or pair-fed to the intake of the leptin-treated group (n = 8) to control for changes of food intake induced by leptin. The specificity of the effect of leptin was further assessed by 1) measuring NPY gene expression in db/db mice (n = 6) that are resistant to leptin, 2) measuring NPY gene expression in brain areas outside the hypothalamus, and 3) measuring the effect of leptin administration on hypothalamic expression of corticotropin-releasing hormone (CRH) mRNA. Five daily intraperitoneal injections of recombinant mouse leptin (150 micrograms) in ob/ob mice lowered food intake by 56% (P < 0.05), body weight by 4.1% (P < 0.05), and levels of NPY mRNA in the hypothalamic arcuate nucleus by 42.3% (P < 0.05) as compared with saline-treated controls. Pair-feeding of ob/ob mice to the intake of leptin-treated animals produced equivalent weight loss, but did not alter expression of NPY mRNA in the arcuate nucleus. Leptin administration was also without effect on food intake, body weight, or NPY mRNA levels in the arcuate nucleus of db/db mice. In ob/ob mice, leptin did not alter NPY mRNA levels in cerebral cortex or hippocampus or the expression of CRH mRNA in the hypothalamic paraventricular nucleus (PVN). Leptin administration to ob/ob mice also markedly reduced serum glucose (8.3 +/- 1.2 vs. 24.5 +/- 3.8 mmol/l; P < 0.01) and insulin levels (7,263 +/- 1,309 vs. 3,150 +/- 780 pmol/l), but was ineffective in db/db mice. Pair-fed mice experienced reductions of glucose and insulin levels that were < 60% of the reduction induced by leptin. The results suggest that in ob/ob mice, systemic administration of leptin inhibits NPY gene overexpression through a specific action in the arcuate nucleus and exerts a hypoglycemic action that is partly independent of its weight-reducing effects. Furthermore, both effects occur before reversal of the obesity syndrome. Defective leptin signaling due to either leptin deficiency (in ob/ob mice) or leptin resistance (in db/db mice) therefore leads directly to hyperglycemia and the overexpression of hypothalamic NPY that is implicated in the pathogenesis of the obesity syndrome.
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PMID:Specificity of leptin action on elevated blood glucose levels and hypothalamic neuropeptide Y gene expression in ob/ob mice. 860 77

In a previous study, we demonstrated that premenopausal women with visceral obesity have hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, characterized by an exaggerated hormone response to corticotropin-releasing factor (CRF) and corticotropin (ACTH) stimulation. The hypothalamic peptide flow that stimulates the pituitary, particularly after a physiological stress challenge, involves not only CRF, but also arginine-vasopressin (AVP), which synergizes the CRF capacity to stimulate pituitary hormone secretion. Previous studies in humans have demonstrated that combining AVP with CRF permits maximal stimulation of the pituitary, providing a more appropriate method of assessing pituitary hormone reserve. We therefore investigated the response of the HPA axis to combined CRF and AVP stimuli in obese women with different obesity phenotypes. Moreover, we examined hormonal and cardiovascular responses to several mental stress tasks, according to previously standardized procedures. Two groups of age-matched premenopausal eumenorrheic obese women with visceral (V-BFD) or subcutaneous (S-BFD) body fat distribution and a group of normal-weight healthy controls were investigated. All women randomly underwent the following protocol: (1) a combined CRF/AVP test (100 micrograms plus 0.3 IU intravenously [IV], respectively); (2) a standardized stress test, which consisted of completing two puzzles and a mental arithmetic test; and (3) a control saline test. Blood samples for ACTH and cortisol determinations were obtained before and during each test, and measurements of arterial blood pressure and pulse rate were made at regular intervals during the stress test. After combined CRF/AVP administration, ACTH and cortisol were significantly higher in V-BFD than in the other two groups. In contrast, no significant hormonal variation was found in either group during stress tasks. During the stress test, pulse rate (but not arterial blood pressure) significantly increased after 8 and 15 minutes in the V-BFD group, whereas no significant variation was found in S-BFD and control women. A significant correlation was present between the pulse rate and change in cortisol level during the stress test at minutes 8 (r=.54, P<.05) and 15 (r=.57, p<.01) in all women considered together. Subjective emotional involvement during stressful tasks was measured by a two-dimensional short verbal scale, which revealed that the stress section had a more significant impact in obese V-BFD than in S-BFD and control women. These data therefore confirm that women with visceral obesity have hyperactivity of the HPA axis, and that the combined CRF/AVP stimulation may offer a good tool for investigating pituitary reserve in this obesity phenotype. Moreover, the results indicate that these women probably have a hyperreactive sympathetic response to acute stress that seems interrelated to that of the HPA axis.
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PMID:Hypothalamic-pituitary-adrenal axis activity and its relationship to the autonomic nervous system in women with visceral and subcutaneous obesity: effects of the corticotropin-releasing factor/arginine-vasopressin test and of stress. 860 43


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