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

The effects of a cafeteria diet on nitrogen balance in lean (Fa/?) and obese Zucker rats (fa/fa) was studied for two consecutive 15 day periods after weaning. Obese rats were able to absorb a lower proportion of dietary nitrogen than the lean controls. Cafeteria diet increased the retention of dietary nitrogen, and lowered urinary nitrogen losses in both obese and lean rats. Urea constituted practically the only product of urinary nitrogen excretion in obese rats, whereas it accounted for only about 75% of that eliminated by Fa/? rats. Nitrogen accretion in the body was highest for the younger animals, and again increased with cafeteria feeding. Obese fa/fa rats showed a lower percentage of body nitrogen retention than their lean counterparts; obese rats were able, however, to accumulate large amounts of nitrogen and fat, in part because of their higher intake. A significant part of the absorbed nitrogen was not found in either the body or the urine; the cafeteria diet markedly increased the weight of this fraction of nitrogen unaccounted for. In conclusion, the effects of cafeteria feeding on weight and nitrogen handling were comparable in lean and obese rats, i.e. the effects of genetic and dietary obesity seem to be additive with regard to nitrogen extraction and excretion for Zucker rats.
 ...
PMID:Nitrogen balances of lean and obese Zucker rats subjected to a cafeteria diet. 131 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.
 ...
PMID:Alteration of somatostatin but not growth hormone-releasing factor pituitary binding sites in obese Zucker rats. 168 74

GH secretion is markedly blunted in obesity; however, the mechanism(s) mediating this response remains to be elucidated. In the present study we examined the involvement of the two hypothalamic GH-regulatory hormones, GH-releasing factor (GRF) and somatostatin (SRIF), using the genetically obese male Zucker rat. Spontaneous GH, insulin, and glucose secretory profiles obtained from free moving, chronically cannulated rats revealed a marked suppression in amplitude and duration of GH pulses in obese Zucker rats compared to their lean littermates (mean 6-h plasma GH level, 3.9 +/- 0.4 vs. 21.5 +/- 3.8 ng/ml; P less than 0.001). Obese rats also exhibited significant hyperinsulinemia in the presence of normoglycemia. The plasma GH response to an iv bolus of 1 microgram rat GRF-(1-29)NH2, administered during peak and trough periods of the GH rhythm, was significantly attenuated in obese rats at peak (137.4 +/- 26.1 vs. 266.9 +/- 40.7 ng/ml; P less than 0.02), although not at trough, times. Passive immunization of obese rats with a specific antiserum to SRIF failed to restore the amplitude of GH pulses to normal values; the mean 6-h plasma GH level of obese rats given SRIF antiserum was not significantly different from that of obese rats administered normal sheep serum. Both pituitary wet weight and pituitary GH content and concentration were reduced in the obese group. Measurement of hypothalamic GRF immunoreactivity revealed a significant (P less than 0.05) reduction in the mediobasal hypothalamic GRF content in obese rats (503.2 +/- 60.1 pg/fragment) compared to that in lean controls (678.1 +/- 50.2 pg/fragment), although no significant difference was observed in hypothalamic SRIF concentration. Peripheral SRIF immunoreactive levels were significantly (P less than 0.01) elevated in both the pancreas and stomach of obese rats. These results demonstrate that the genetically obese Zucker rat exhibits 1) marked impairment in both spontaneous and GRF-induced GH release, which cannot be reversed by SRIF immunoneutralization, 2) significant reduction in pituitary GH concentration, 3) depressed hypothalamic GRF content, and 4) elevated gastric and pancreatic, but not hypothalamic, SRIF levels. The findings suggest that the defect in pituitary GH secretion observed in the genetically obese Zucker rat is due, at least partially, to insufficient stimulation by hypothalamic GRF, and that SRIF does not play a significant role.
 ...
PMID:Mechanisms of impaired growth hormone secretion in genetically obese Zucker rats: roles of growth hormone-releasing factor and somatostatin. 197 30

Obese patients are characterised by several neuroendocrine abnormalities, including characteristically a decrease in growth hormone responsiveness to GH-releasing hormone. In normal subjects, the GH response to GHRH is enhanced by the acetylcholinesterase inhibitor, pyridostigmine. We have studied the effect of this drug on GH secretion in gross obesity. Twelve obese patients were studied (mean weight 156% of ideal) and compared with a group of 8 normal volunteers. Each subject was initially studied on two occasions, in random order, with GHRH (1-29) NH2 100 micrograms iv alone and following pretreatment with pyridostigmine 120 mg orally one hour prior to GHRH. In obese patients, the GH response to GHRH was significantly blunted when compared to controls (GH peak: 20 +/- 4 vs 44 +/- 16 micrograms/l; mean +/- SEM). After pyridostigmine, the response to GHRH was enhanced in the obese subjects, but remained significantly reduced compared to non-obese subjects treated with GHRH and pyridostigmine (GH peak: 30 +/- 5 vs 77 +/- 20 micrograms/l, respectively). In 6 subjects, higher doses of GHRH or pyridostigmine did not further increase GH responsiveness in obese patients. Our results suggest that obese patients have a disturbed cholinergic control of GH release, probably resulting from increased somatostatinergic tone. This disturbed regulation may be responsible, at least in part, for the blunted GH responses to provocative stimuli.
 ...
PMID:Pyridostigmine enhances, but does not normalise, the GH response to GH-releasing hormone in obese subjects. 210 45

We have previously reported an impaired growth hormone (GH) response and abnormal prolactin release to insulin-hypoglycaemia in obesity. We suggested that obese women with an absent prolactin response to hypoglycaemia ('non-responders') have a disorder of hypothalamic function. We have now investigated the GH response to i.v. growth hormone releasing factor, GHRF (1-29)NH2, in 14 obese women and nine age-matched normal-weight women. We found a significantly reduced GH response to GHRF in the obese women as compared with controls (mean peak +/- SEM: obese 8.9 +/- 2 mu/l, controls 28 +/- 2 mu/l; P less than 0.01). When the obese women were divided on the basis of their prolactin response to insulin-hypoglycaemia (seven 'non-responders', mean weight 102 +/- 5 kg; seven responders, mean weight 108 +/- 8 kg) a similar GH response to GHRF was found between the two groups but the GH response to hypoglycaemia was significantly less in the 'non-responder' women (mean peak 'non-responders' 10.5 +/- 3 mu/l, responders 27 +/- 4 mu/l; P less than 0.05). We conclude that obesity may be characterized by an impaired GH response to both i.v. GHRF and insulin-hypoglycaemia, which suggests altered hypothalamic-pituitary function. The finding that the GH response to hypoglycaemia is significantly less in the obese prolactin 'non-responder' women supports the hypothesis for a hypothalamic disorder.
 ...
PMID:Impaired growth hormone response to growth hormone releasing factor and insulin-hypoglycaemia in obesity. 286 16

We have recently reported an impaired growth hormone (GH) response to a single i.v. bolus dose of growth hormone releasing factor (1 microgram/kg body weight) in obese women. We have now investigated whether the i.v. administration of low dose GHRF(1-29)NH2 (0.33 microgram/kg/h) by 15 min pulsed injections for 3 h followed by an i.v. bolus (1 microgram/kg) to four normal weight women and six obese women results in an enhancement of GH release. In the control women low dose GHRF, given either as a single 10 microgram injection or in pulses of equivalent total dosage, produced a GH response identical to that seen after a single bolus of 60 micrograms (mean peak GH low dose 30 +/- 2 mU/l, peak GH large dose 30 +/- 0.5 mU/l). In the obese women GH release was significantly less than the controls after low doses of GHRF (P less than 0.01) and the peak was delayed compared to that following a single large bolus dose (peak GH 7 +/- 1.2 mU/l). However, three of the obese women who previously showed no response to a large dose of GHRF did release GH after low dose pulsed injections. The final bolus of GHRF after 3 h of pulsed injections did not elicit any additional GH release in the subjects irrespective of body weight. We conclude that obesity may be characterized by impaired GH release to i.v. GHRF. The finding that some obese women do not respond to a single large dose injection of GHRF but do release GH after low dose pulsed injections supports the hypothesis of a hypothalamic disorder in these women.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Growth hormone response to low dose intravenous injections of growth hormone releasing factor in obese and normal weight women. 287 50

Growth hormone (GH) responses to GRF (1 microgram/kg BW i.v.) were investigated. Comparison between GRF(1-40) and GRF(1-29)NH2 in 11 young adult volunteers gave identical results. One hundred and thirty-one children and adolescents (45 with idiopathic GHD) were tested with GRF (1-29)NH2. The maximal GH levels (max GH) in response to GRF during the 120 min test period were found suitable to characterize the response. In cases without GHD no correlation to age, sex and pubertal development was observed. A maximal GH level of above 10 ng/ml was found to be normal. In 3 out of 86 children without GHD (one with Turner syndrome; two with simple obesity) max GH fell short of 10 ng/ml, while 11 of 45 cases with GHD exceeded this margin. In GHD, max GH was inversely correlated with age. There was no difference in max GH between groups with or without perinatal pathology as a presumed cause of GHD. GH levels to GRF were positively correlated with maximal GH level during sleep in GHD, but not correlated with responses seen to insulin or arginine. The value of GRF testing for the confirmation of GHD is discussed in the light of other GH stimulatory tests and basal somatomedin C measurements. It is suggested that the combination of testing with GRF and the determination of a basal SmC level offers a safe and convenient way to diagnose GHD in clinically suspected cases, though in some cases further diagnostic tests may be needed.
 ...
PMID:Testing with growth hormone-releasing factor (GRF(1-29)NH2) and somatomedin C measurements for the evaluation of growth hormone deficiency. 288 Jul 20

Synthetic human GRF (hGRF (1-44) NH2; SM-8144) was administered as an iv bolus to 141 normal children of short stature (NSC), 73 patients with severe idiopathic GH deficiency (IGD; group A), 30 patients with mild idiopathic GH deficiency (IGD; group B), 29 patients with secondary GH deficiency, 3 patients with primary hypothyroidism, 21 patients with Turner's syndrome and 25 patients with various other disease. Their height was below normal for their age and sex, and they were all below 25 years old without obesity. The maximal GH responses (M+SEM) were 39.5 +/- 2.2, 7.2 +/- 0.9, 27.2 +/- 3.7, 5.2 +/- 0.8, 9.7 +/- 4.4, 25.1 +/- 2.8 and 32.3 +/- 4.8 ng/ml, respectively (significance from the NSC, ; p less than 0.05, ; p less than 0.001). The GH responses to hGRF were greater than those elicited by standard pharmacological tests. There was a negative correlation between bone age and peak plasma GH response to hGRF in patients with idiopathic GH deficiency (IGD) but not in normal children (NSC). In twenty-two percent of the patients with IGD in group A the response was above 10 ng/ml and in 57% of the patients with IGD in group B the response was above 20 ng/ml, suggesting that a large percentage of patients with idiopathic GH deficiency lack hypothalamic GRF. The side effect of flushing was observed in 15.2% of all subjects. These results indicate the potential usefulness of hGRF (1-44) NH2 (SM-8144) in inducing GH release from the pituitary.
 ...
PMID:Plasma growth hormone (GH) response to GH-releasing factor (SM-8144) in children of short stature and patients with GH deficiency. 311 40

Increased plasma concentrations of growth hormone (GH) are reported in diabetes and it is suggested that this may be important in the development of complications. We have investigated fasting GH levels and the response to 100 micrograms i.v. growth hormone releasing factor, GRF(1-29)NH2, in age-matched men: six normal weight controls, six obese controls, six insulin-dependent diabetics, six normal weight non-insulin dependent diabetics and six obese non-insulin dependent diabetics. None of the diabetic men had clinical evidence of diabetic complications. Fasting GH values did not differ significantly between the five groups. The peak GH response to GRF was similar in the controls, insulin-dependent diabetics (IDD) and non-insulin dependent (NIDD) normal weight diabetics (mean peak +/- SEM: controls 25.5 +/- 5 mU/l, IDD 26.5 +/- 6 mU/l, NIDD 19.7 +/- 5 mU/l) but was significantly reduced in the two obese groups (obese 6.4 +/- 3 mU/l, obese diabetics 4.5 +/- 1 mU/l, P less than 0.01). This impairment of GH secretion was unrelated to either fasting plasma insulin or glucose concentration. We conclude that our results do not confirm the previous reports of abnormal GH secretion in diabetes but do demonstrate a markedly impaired GH response to GRF to be a feature of obesity.
 ...
PMID:Growth hormone response to growth hormone releasing factor in diabetic men. 313 33

Very-low-calorie diets (less than 500 kcal/day; VLCD) are widely used for the treatment of severe obesity. We report the effects of such diets, consisting of proteins only or proteins and carbohydrates (CH), on nitrogen balance and protein nutritional status of morbidly obese patients. Cumulative nitrogen loss, serum albumin, transferrin, prealbumin (PA) and retinol-binding protein (RBP) concentrations, and plasma amino acid profile were determined in two groups of obese patients: 5 subjects (3 women, 2 men: BMI 55.3 +/- 2.2 kg/m2) subjected for 4 weeks to a protein VLCD (40 g protein + 2 g fat) and 7 others (4 women, 3 men: BMI 45.6 +/- 2.8 kg/m2) received for the same length of time a protein + CH VLCD (34 g protein + 26 g CH). Nitrogen balance was determined weekly whilst plasma and serum variables were measured on days 0, 3, 5, 10, 20 and 28 of treatment. Nitrogen balance did not significantly differ between the two groups of patients throughout the treatment. Serum PA and RBP concentrations decreased from day 5 and day 10, respectively, in both groups. Plasma amino acids showed a similar pattern in the protein and protein + CH groups. Alanine gradually decreased below baseline values; after a peak value on day 5, branched-chain amino acids (valine, leucine, isoleucine) returned to baseline values in both groups. In conclusion, in severely obese patients subjected to VLCD, nitrogen balance, labile protein concentrations and plasma amino acid profile are not significantly affected by adding CH to proteins.
 ...
PMID:Protein balance during very-low-calorie diets for the treatment of severe obesity. 359 20


1 2 3 4 5 6 7 8 9 10 Next >>