Search PubMed⌕ Search

Biomedical subjects

G A Bray

Publications and source records attributed to G A Bray.

At least 127 records · Page 7Linked to original sources
PubMed1996

Comparison of Osborne-Mendel and S5B/PL strains of rat: central effects of galanin, NPY, beta-casomorphin and CRH on intake of high-fat and low-fat diets.

The effects of central administration of galanin, neuropeptide Y (NPY), beta-casomorphin(1-7) and corticotropin releasing hormone (CRH) on intake of either a high-fat or low-fat diet have been compared in two strains of rat, the dietary fat-sensitive Osborne-Mendel (OM) rat and the dietary fat-resistant S5B/Pl rat. Injection of galanin (0.1, 0.3 nmoles) into the 3rd cerebral ventricle stimulated the intake of both a high-fat and a low-fat diet in OM rats in a dose dependent manner but the response was significantly smaller in rats fed the low-fat diet. In S5B/Pl rats, galanin had a small stimulatory effect on food intake but only at a high dose (2 nmole). Beta-casomorphin(1-7) (5 nmoles), an opioid-like peptide, increased the intake of the high-fat but not the low-fat diet in OM rats, whereas S5B/Pl rats fed either a high-fat or low-fat diet did not respond to beta-casomorphin(1-7). Both strains showed a similar stimulatory response to NPY (0.1, 0.5 nmoles) on the intake of the high-fat or low-fat diet, but the magnitude of the response was attenuated in S5B/Pl rats. In contrast, the anorectic effects of CRH (0.26 nmoles) on food deprived animals was similar in both strains for both diets. We speculate that the regulatory system controlling the intake of fat activated by galanin and beta-casomorphin(1-7) may be defective in S5B/Pl rats.

Animals↗
PubMed1996

A double-blind randomized placebo-controlled trial of sibutramine.

Sibutramine is a beta-phenethylamine which blocks reuptake of norepinephrine and serotonin. In this clinical study, a group of 173 patients were randomized to treatment with sibutramine at doses of 1, 5, 10, 15, 20 or 30 mg/d and were compared with placebo in a 24-week double-blind trial. There was a dose-dependent reduction in body weight, with doses of 10, 15, 20 and 30 mg being significantly greater than placebo. Weight loss was still continuing in the highest three doses at the end of the study. When drugs were discontinued patients regained weight, as expected. Side effects were generally mild and were most evident in the group treated with the highest dose. These studies suggest that sibutramine may be a valuable new drug for treatment of obesity.

Adolescent↗
PubMed1996

Effects of pyruvate and lactate on food intake in rat strains sensitive and resistant to dietary obesity.

We have investigated the effects of peripherally administered pyruvate and lactate on the intake of high fat (HF) and low fat (LF) diets by a strain of rat either sensitive (Osborne-Mendel, OM) or resistant (SSB/Pl) to high fat-induced obesity. Both pyruvate and lactate inhibited the intake of HF and LF diets by OM rats and these effects were blocked by selective hepatic vagotomy. In contrast, in S5B/Pl rats fed an LF diet the responses to pyruvate and lactate were attenuated and were absent in S5B/Pl rats fed the HF diet. These data suggest that OM and S5B/Pl rats differ either in their metabolism of pyruvate and lactate or in their responses to these metabolites.

Animals↗
PubMed1996

Opioid receptor subtype control of galanin-induced feeding.

This study examined the effects of specific antagonists to kappa- and mu-opioid receptors on the feeding induced by injecting galanin into the lateral cerebral ventricle (LCV). Galanin injected into the lateral cerebral ventricle of sated rats stimulated the consumption of high-fat diet when compared to controls injected with saline vehicle. The mu-opioid receptor antagonist, CTOP, completely abolished galanin-induced feeding in sated rats whereas the kappa-opioid receptor antagonist, nor-BNI, had no effect on galanin-induced feeding. Neither CTOP nor nor-BNI alone produced any change in food consumption in sated rats. In fasted rats, on the other hand, nor-BNI significantly decreased consumption of a high-fat diet (> 83%) when compared to animals treated with the saline vehicle, whereas CTOP had no significant effect. These findings suggest that galanin-induced feeding of a high-fat diet is selectively modulated by a pathway involving mu-opioid receptors whereas feeding induced by fasting is dependent on a pathway mediated by kappa-opioid receptors. These data also suggest that galanin does not mediate the feeding response after fasting.

Animals↗
PubMed1996

Effects of dietary preference and galanin administration in the paraventricular or amygdaloid nucleus on diet self-selection.

Microinjection of galanin into the paraventricular nucleus (PVN) of the hypothalamus has been reported to predominantly increase dietary fat consumption during the light or late dark periods. However, there have been no studies of the macronutrient-specific effects of galanin administered into the amygdala (AMY). We used male Sprague-Dawley rats to test the effect of galanin administered into the PVN or central nucleus of the AMY on diet selection using two different protocols: the two-choice composite diet (10% or 55% energy as fat) (Study 1) or the three-choice macronutrient diet (Study 2). In the first study, total food intake was significantly increased 60 min after galanin injection (0.3 nmol) into either the PVN or AMY, but there was no difference in intake between the low- and high-fat diets. In Study 2, using the three-choice macronutrient diet, the feeding stimulation produced by galanin in the PVN also was not diet-dependent. In the AMY, there was a significant effect of diet on the feeding response to galanin, due primarily to the lack of stimulation of protein intake, whereas the intakes of fat and carbohydrate were not significantly different. In summary, there was no difference in the effect of galanin on fat versus carbohydrate intake for either nuclei, whether animals were injected during the light or the late-dark phase. Because rats often display preferences when allowed to choose among individual macronutrient sources, we also examined the relationship between baseline macronutrient preference and the feeding response to galanin in groups of highly fat-preferring and carbohydrate-preferring rats (Study 3). After PVN galanin injection, fat-preferring rats demonstrated significant increases in their consumption of both carbohydrate and fat, whereas carbohydrate-preferring rats responded by eating carbohydrate almost exclusively. There were significant positive associations between baseline macronutrient intake and galanin-induced intake. The results of these studies combined suggest that the effect of galanin on macronutrient selection is not specific for fat and that underlying macronutrient preferences are important in determining the feeding response to galanin.

Amygdala↗
PubMed1996

Body composition and childhood obesity.

Underwater weighing has been the gold standard for the measurement of body composition in humans; however, the two formulas widely used, the Siri and Bronze, were developed using young adult white males. The development of newer techniques in the past 20 years has greatly expanded the accuracy and ease of measuring body composition. These methods have improved the ability to model relationships between body compartments. This article reviews the compartmental models and then critiques the methods available to measure body composition.

Adolescent↗
PubMed1996

Health hazards of obesity.

Several health hazards and social disabilities are associated with obesity. Increased mortality is associated with increased body weight. A high rate of mortality results from heart disease, diabetes mellitus, gallbladder disease, high blood pressure, and cancer. Physiologic cardiovascular changes occur, leading to left ventricular hypertrophy and lipid abnormalities. Hypertension, stroke, and venous stasis are increased. Pulmonary abnormalities include obstructive sleep apnea, which can be associated with secondary polycythemia and right ventricular hypertrophy. Gallstones, gallbladder disease, and accumulation of fat on the liver are significantly increased. Gout and reproductive abnormalities in women are common. Osteoarthritis of the knees and spine occur, although osteoporosis is rare. Risk for endometrial and breast cancer is increased, particularly in the presence of increased central fat. Changes in the skin include stretch marks, acanthosis negricans, hirsutism, intertrigo, and multiple papillomas. Impaired psychosocial function is manifested as social isolation, loss of job mobility, increased employee absenteeism, and economic and social discrimination.

Female↗
PubMed1996

Pyruvate and hepatic pyruvate dehydrogenase levels in rat strains sensitive and resistant to dietary obesity.

This study compared the effects of exogenous pyruvate and lactate on the serum levels of pyruvate, lactate, glucose, alanine, and insulin, as well as the activity of hepatic pyruvate dehydrogenase (PDH) in strains of rat that were either sensitive [Osborne-Mendel (OM)] or resistant (S5B/Pl) to high-fat diet-induced obesity. Serum pyruvate and lactate were significantly higher and glucose lower in ad libitum-fed OM rats, but these differences disappeared after an 18-h fast. The increase in pyruvate and lactate after exogenous pyruvate administration was significantly greater in S5B/Pl rats than OM rats. There were no differences in serum alanine with strain or diet. The total PDH activity was similar across strains and diets but the proportion of PDH in its activated form (PDHa) was decreased in ad libitum-fed S5B/Pl rats. Pyruvate injection increased insulin and hepatic PDHa activity in OM rats fed both high- and low-fat diets, but these responses were greatly attenuated or absent in S5B/Pl rats. The data are consistent with the hypothesis that modulation of carbohydrate oxidation by PDH may be related to susceptibility to obesity when rats are fed a high-fat diet.

Animals↗
PubMed1996

Exogenous androgens influence body composition and regional body fat distribution in obese postmenopausal women--a clinical research center study.

Abdominal fat distribution is influenced by androgen levels in both men and women. The purpose of this study was to assess the effects on fat distribution of administering nandrolone decanoate (ND; an anabolic steroid with weak androgenic activity) or spironolactone (SP; an antiandrogen) in obese postmenopausal women. The design was a randomized, placebo-controlled, 9-month trial with simultaneous calorie restriction for weight loss. Women in all three groups lost comparable amounts of weight, but the ND-treated women gained lean mass relative to the other two groups (P < 0.0005) and lost more body fat than women in the SP group (P < 0.01). The resting metabolic rate also increased slightly in the ND group. ND treatment produced a gain in visceral fat, as determined by computed tomography scan, and a relatively greater loss of sc abdominal fat. SP-treated women lost significantly less sc fat than the other two groups. Serum cholesterol decreased in the placebo group, but increased slightly in the other two groups (significant for SP vs. placebo, P < 0.05). High density lipoprotein cholesterol decreased significantly in the ND-treated women. There were no significant changes in fasting glucose or insulin sensitivity. We conclude that administration of exogenous androgens modulates body composition in obese postmenopausal women and independently affects visceral and sc abdominal fat.

Adipose Tissue↗
PubMed1995

Differential effects of enterostatin, galanin and opioids on high-fat diet consumption.

Enterostatin, the activation peptide of pancreatic procolipase, suppresses high-fat diet consumption both centrally and peripherally. kappa-opioid agonists are also known to stimulate fat intake. These experiments were conducted to determine if an opioidergic central pathway might mediate the effects of enterostatin and galanin on fat intake. Male Sprague-Dawley rats were adapted to a high-fat diet (56% energy) and were implanted with cannulae aimed at the lateral cerebral ventricle (LV) or third cerebral ventricle (3V). Injection of enterostatin (1 nmol, LV) suppressed high-fat diet consumption in fasted (20 h) rats. This inhibition of high-fat intake by enterostatin was attenuated by central injection of the specific kappa-agonist U50488 (2.15, 21.5 and 215 nmol, LV) in a dose-dependent manner in fasted rats while only the highest dose of U50488 (215 nmol, LV) independently produced stimulation of high-fat diet consumption in sated rats. Galanin (0.1 nmol, 3V) induced consumption of high-fat diet in sated rats similar to that seen with U50488 and this stimulation was attenuated by peripheral injection of naloxone (1.0 mg/kg i.p.). We present a model which integrates the present data, as well as previous findings, in explaining a potential common opioid pathway modulating fat consumption.

Animals↗
PubMed1995

Energy expenditure in lean and obese prepubertal children.

The relationship between energy expenditure and obesity was examined in prepubertal children. Consenting fifth graders underwent Tanner Staging, weight, height and skinfold measurements. Subjects were selected for further study to obtain equal numbers of girls and boys with a wide range of body composition. Weight, total daily energy expenditure (TDEE) by doubly labeled water (DLW), resting metabolic rate (RMR), and body composition were measured. Children were grouped into level of obesity based on tertiles of subscapular plus triceps skinfolds. The skinfold tertiles did quite well in grouping subjects by degree of obesity, as differences in percent fat in each tertile were significantly different. There were no differences in fat-free mass between the groups, while the highest tertile group weighed 14 kg more than the lowest. For DLW, energy expenditure was calculated using day 8 and day 9 urine samples as the final time point to examine precision. Mean energy expenditure using either day was nearly identical (2220 +/- 400 vs 2300 +/- 370 kcal/d), with a CV of the difference of 5.5%. No differences in RMR, energy expended in activity, or TDEE between the three groups were observed. A reduction in RMR or TDEE could not explain differences in obesity in these prepubertal children. However, the fact that the heaviest children expended the same amount of energy in activity and had the same TDEE as the leanest, while weighing 14 kg more, indicates that the obese children had a reduced activity level.

Absorptiometry, Photon↗
PubMed1995

The association of body weight, dietary intake, and energy expenditure with dietary restraint and disinhibition.

The hypotheses that dieting and/or overeating are associated with adiposity, eating disturbances, and lowered energy expenditure were tested in this study. A sample of 44 premenopausal women scoring high and low on measures of dietary restraint and disinhibition of dietary control, as measured by the Three Factor Eating Questionnaire, was studied. A 2 x 2 factorial design was employed (High/Low restraint x High/Low Disinhibition). Dependent variables were: body composition, dietary intake, activity, resting metabolic rate, and thermic effect of food. Unrestrained overeaters (Low Restraint/High Disinhibition group) were very obese. High Dietary Restraint was associated with intent to diet and controlled eating. High scores on the Disinhibition Scale were associated with episodic overeating. Groups did not differ in resting metabolic rate (controlled for fat-free mass). Lower thermic effect of food was found to be associated with the obesity found in High Disinhibition subjects. Thus, Dietary Restraint was not associated with significant adverse effects upon physical or psychological health. High Disinhibition, however, was associated with adiposity and significant disturbances of eating.

Adipose Tissue↗