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

The endocrine abnormalities along the growth hormone (GH) axis in anorexia nervosa (AN) and in obesity include hypothalamic, pituitary, and peripheral elements. The present study was undertaken to evaluate the effects of these nutritional extremes on GH-binding protein (BP) levels and on Insulin-like growth factor-I (IGF-I) receptors on red blood cells (RBC). Nine patients with AN and 20 obese subjects were compared with normal control children, adolescents, and adults. GH-BP was measured by a binding assay with dextran-coated charcoal separation. IGF-I binding was measured on enriched RBC. Serum GH-BP levels were markedly reduced in the AN patients, and highly increased in the obese. Scatchard analyses showed linear plots with unaltered binding affinities (Ka). The binding capacity (Bmax) was significantly lower than normal control in the AN patients and higher in the obese. GH-BP levels correlated positively with the body mass index (BMI). RBC [125I]IGF-I binding was significantly elevated in the AN patients and low in the obese. Scatchard analyses showed curvilinear plots. The high-affinity constants (Ka1) were slightly, but significantly, higher in the AN patients and in the obese compared with control. The binding capacity of the first binder (Bmax1) was lower in obesity than in AN or control. The low-affinity constants (Ka2) were similar in the three groups, and its binding capacity (Bmax2) was similar in the AN patients and the controls, but significantly lower in the obese. [125I]IGF-I binding correlated negatively and significantly with the BMI and with the GH-BP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The distal axis of growth hormone (GH) in nutritional disorders: GH-binding protein, insulin-like growth factor-I (IGF-I), and IGF-I receptors in obesity and anorexia nervosa. 131 1

Obesity in childhood is characterized by subnormal integrated concentrations of growth hormone (IC-GH) and elevated integrated concentrations of insulin (IC-I). We tested whether a reduction of IC-I induced by a low calorie diet would lead to a rise of IC-GH into the normal range for age. Six obese children (body mass index (BMI) 39.1 +/- 9.2 kg/m2) underwent integrated concentration (IC) studies by continuous withdrawal before and again 5-8 weeks after being on a low calorie diet. In response to the diet BMI was lower 34.7 +/- 9.4 kg/m2 (P less than 0.003), and IC-I was considerably reduced, 479 +/- 255 pM initially vs. 109 +/- 109 pM on the diet, P less than 0.0008. IC-GH increased modestly from 1.6 +/- 0.6 micrograms/l initially to 2.4 +/- 0.6 micrograms/l, P less than 0.01 on the diet. None of the patients had repeat IC-GH levels which were above the lower limit of normal for lean children of normal stature (3.2 micrograms/l). Single sample insulin-like growth factor 1 (IGF-1) levels were unchanged: 40.9 +/- 23.1 nM initially vs. 49.7 +/- 25.7 nM (314.6 +/- 197.7 vs. 382.5 +/- 217.0 ng/ml, n.s.). Thus reduction of high insulin concentrations during 5-8 weeks of a low calorie diet has only a small effect on IC-GH in obese children. Factors other than circulating insulin levels are likely to play the major role in mediating the reduced levels of GH observed in obesity.
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PMID:Reduction of plasma insulin levels does not restore integrated concentration of growth hormone to normal in obese children. 132 72

Preobese fetuses have elevated thyroid hormone levels and depressed growth hormone levels relative to lean fetuses. Therefore, we are studying various experimental fetal pig models to explore the relationship between endocrine status and onset of obesity. In the present study, intact and hypophysectomized (d 70) fetuses were implanted with thyroxine (T4) pellets on d 70 of gestation, and blood, adipose tissue, and skin samples were obtained upon removal of d 90 of gestation. Body weights were similar for all groups and T4 treatment reversed myxedema in hypophysectomized fetuses. Serum T4 levels were elevated (p less than 0.05) and skin and hair development were enhanced (p less than 0.05) to a similar degree by T4 treatment in intact and hypophysectomized fetuses. However, T4 did not influence adipose tissue development in intact fetuses, but markedly enhanced development in hypophysectomized fetuses. For instance, fat cell size and lipogenic enzyme activities in hypophysectomized fetuses were increased (p less than 0.05) by 5-mg and 15-mg T4 treatments, with a marked increase (p less than 0.05) in apparent fat cell number with the 15-mg T4 treatment. In contrast, there was no effect of T4 (15 mg) on these parameters in intact fetuses. Therefore, fetal obesity may be directly associated with elevated thyroid hormone levels and suppressed growth hormone levels, but not with elevated T4 levels alone.
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PMID:The influence of thyroxine on the differentiation of adipose tissue and skin during fetal development. 150 11

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

A blunted growth hormone (GH) response to several stimuli, including growth hormone-releasing hormone (GHRH), has been shown in obesity. Arginine (ARG) has been demonstrated to potentiate the GHRH-induced GH increase in normal subjects, likely acting via inhibition of hypothalamic somatostatin release. To shed further light onto the mechanisms underlying the blunted GH secretion in obesity, we studied the effect of ARG (0.5 g/kg infused intravenously [IV] over 30 minutes) on both basal and GHRH (1 micron/kg IV)-stimulated GH secretion. Eight obese subjects (aged 26.4 +/- 3.9 years; body mass index, 39.0 +/- 1.9 kg/m2) and eight normal control volunteers (aged 27.0 +/- 1.7 years; body mass index, 22.3 +/- 0.5 kg/m2) were studied. In obese subjects, the GH response to both GHRH and ARG was lower (P less than .01 and P less than .002, respectively) than in controls. ARG potentiated the GH response to GHRH in obese patients (P less than .0003). However, in these patients, the GH secretion elicited by GHRH, even when coadministered with ARG, persisted at reduced levels (P less than .005) when compared with controls. Basal insulin-like growth factor-1 (IGF-1) levels did not significantly differ in obese subjects and in normal subjects (161.1 +/- 37.0 v 181.0 +/- 12.8 micrograms/L). In conclusion, ARG enhances the blunted GHRH-induced GH increase in obese patients, but the GH responses to ARG alone and to ARG + GHRH persist at lower levels than in normals. Thus, our results suggest the existence of a reduced pituitary GH pool in obesity.
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PMID:Arginine potentiates but does not restore the blunted growth hormone response to growth hormone-releasing hormone in obesity. 158 39

Insulin-like growth factor-I (IGF-I) and insulin interact with related receptors to lower plasma glucose and to exert mitogenic effects. Recombinant human IGF-I (rhIGF-I) was recently shown to decrease serum levels of insulin and C-peptide in fasted normal subjects without affecting plasma glucose levels. In this study we have investigated in six healthy volunteers the responses of glucose, insulin, and C-peptide levels to intravenous rhIGF-I infusions (7 and 14 micrograms/kg.h) during standard oral glucose tolerance tests (oGTT) and meal tolerance tests (MTT), respectively. Glucose tolerance remained unchanged during the rhIGF-I infusions in the face of lowered insulin and C-peptide levels. The decreased insulin/glucose-ratio presumably is caused by an enhanced tissue sensitivity to insulin. The lowered area under the insulin curve during oGTT and MTT as a result of the administration of rhIGF-I were related to the fasting insulin levels during saline infusion (oGTT: r = 0.825, P less than 0.05; MTT: r = 0.895, P less than 0.02). RhIGF-I, however, did not alter the ratio between C-peptide and insulin, suggesting that the metabolic clearance of endogenous insulin remained unchanged. In conclusion, rhIGF-I increased glucose disposal and directly suppressed insulin secretion. RhIGF-I probably increased insulin sensitivity as a result of decreased insulin levels and suppressed growth hormone secretion. RhIGF-I, therefore, may be therapeutically useful in insulin resistance of type 2 diabetes, obesity, and hyperlipidemia.
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PMID:Effects of insulin-like growth factor-I on glucose tolerance, insulin levels, and insulin secretion. 160 98

The sequence identity of growth hormone-binding protein (GH-BP) with the extracellular domain of GH receptors raised the possibility that circulating GH-BP might affect the binding of human GH (hGH) to its receptors, and thus, its biological effects. To test this hypothesis, we tested the effects of sera with low GH-BP levels (obtained from prepubertal children, girls with anorexia nervosa [AN], and patients with hepatic cirrhosis), normal control sera, and sera with high GH-BP levels (obtained from obese patients) on hGH binding to its receptors. GH-BP activity in patients' sera was measured by incubation with [125I]hGH and the separation of bound hGH from free hGH with dextran-coated charcoal. The effect of GH-BP was studied by preincubation of patients' sera with increasing concentrations of hGH, followed by incubation with [125I]hGH and a rabbit liver membrane preparation known to be rich in GH receptors, and finally by measuring hGH bound to the receptors. In this study, we report on the ability of GH-BP to reduce the inhibitory capacity (IC50) of hGH on [125I]hGH binding to GH receptors. The concentration of GH-BP in serum is positively correlated with the IC50 of hGH incubated with different sera on [125I]hGH binding to its receptors (n = 21; r = .886, P less than .001). In the presence of high serum GH-BP levels, such as those observed in obesity (20.13% +/- 0.71%/0.05 mL serum), the IC50 values were significantly higher than those obtained with sera containing GH-BP levels lower than those measured in human control subjects, such as from prepubertal children, AN patients, and cirrhotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of human growth hormone (GH)-binding protein in human serum on GH binding to rabbit liver membranes. 161 92

(SLN x C3H/He)F1 mice of both sexes showed significantly heavier body weights than the parental strains associated with the higher food intake and an accumulation of adipose tissue in the subcutaneous and the abdominal regions. Furthermore, serum levels of free fatty acid and growth hormone of F1 mice were higher and lower, respectively, than those of the parental strains. The results indicate that the obesity of these F1 mice is ascribed to excess food intake and metabolic disorders and they are promising as an animal model for the study of several diseases related to obesity.
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PMID:Some physiological characteristics of (SLN X C3H/He)F1 obese mice. 162 44

Rats, neonatally treated with monosodium aspartate (MSA), exhibited developmental defects through adulthood that were characterized by stunted growth, obesity, and reduced size of the liver, kidney, adrenals, and pituitary. Adult male and female rats treated with 4 mg of MSA had no detectable plasma growth hormone as determined from serial blood samples taken every 15 min for 8 consecutive hr. Associated with this loss of circulating growth hormone in the males was a dramatic decline in in vivo and in vitro hexobarbital metabolism and hepatic cytochrome P450 to female levels. The loss of plasma growth hormone in the females had no effect on the already low levels of hepatic monooxygenases. At 2 mg/g body weight, MSA produced both sex- and dose-dependent effects that were far more subtle than the full-blown obesity and growth retardation associated with the larger 4-mg dose. While the mean concentration of circulating growth hormone was reduced 70 to 90% in 2-mg-MSA-treated rats, the sexually dimorphic, ultradian patterns of growth hormone secretion were undisturbed. Affected males continued to secrete a pulse of growth hormone every 3 hr, albeit at greatly reduced amplitudes, interposed by normally undetectable baselines. Similarly, 2-mg-MSA-treated females had greatly reduced mean levels of plasma growth hormone, but with the usual secretion of multiple pulses never dropping to baseline. Surprisingly, the sex-dependent, hepatic monooxygenases, which are normally regulated by the ultradian secretions of growth hormone, were unaffected by the 2-mg MSA treatment. Our results suggest that while an ultradian pulse of circulating growth hormone is necessary for the characteristically male profile of hepatic monooxygenases, neither the amplitude of the secretory peaks nor their total growth hormone content is critical.
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PMID:Sex- and dose-dependent effects of neonatally administered aspartate on the ultradian patterns of circulating growth hormone regulating hexobarbital metabolism and action. 167 77

The present study was designed to determine whether the diminution of growth hormone (GH) secretion that occurs in obese Zucker rats is related to alterations of GH-releasing factor (GRF) or somatostatin (SRIF) pituitary binding sites. Cold saturation studies were performed in pituitary homogenates of 4-month-old lean and obese rats, using [125I-Tyr10]hGRF(1-44)NH2 as radioligand and [127I-Tyr10]hGRF-(1-44)NH2 as competitor, and in pituitary membrane preparations, using [125I-Tyr0, D-Trp8]SRIF14 as radioligand and [127I-Tyr0, D-Trp8]SRIF14 as competitor. In lean rats, analysis of the curves by the Ligand program revealed the presence of two distinct classes of GRF binding sites, the first being of high affinity (0.74 +/- 0.11 nM) and low capacity (118 +/- 31 fmol/mg protein), the second being of lower affinity (880 +/- 240 nM) and higher capacity (140 +/- 35 pmol/mg protein), and of a single class of SRIF binding sites (affinity: 0.40 +/- 0.12 nM; capacity: 24 +/- 6 fmol/mg protein). In obese rats, no difference was observed in GRF binding parameters for both classes of sites, but the concentration of somatostatin binding sites was reduced by 67% when compared to their lean littermates. These findings suggest that the SRIF pituitary receptors are down-regulated in obese Zucker rats and indicate that no alteration of GRF pituitary binding sites contribute to the blunted GH secretion observed in this model of obesity.
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PMID:Alteration of somatostatin but not growth hormone-releasing factor pituitary binding sites in obese Zucker rats. 168 74


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