Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020505 (hyperphagia)
 6,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This experiment examined the effects of diet and photoperiod on food intake, body weight, and brown adipose tissue (BAT) activity in female Siberian hamsters (Phodopus sungorus sungorus). BAT function was assessed by measuring both the sympathetic nervous system activity of BAT [estimated by the rate of norepinephrine (NE) turnover] and BAT thermogenic activity (estimated by GDP binding to BAT mitochondria). Nineteen weeks of high-fat feeding in long photoperiod [16:8 light-dark cycle (LD)] caused a 20% increase in food intake but did not affect body weight. Both NE turnover rate and GDP binding in interscapular BAT (IBAT) were increased four- to eightfold relative to that from chow-fed controls. Thus it appears that in Siberian hamsters BAT can serve the same energy-dissipating function during diet-induced overeating previously established in rats and mice. Nineteen-week exposure to a short photoperiod (LD 8:16) produced a reduction in body weight but did not affect food intake. Both NE turnover rate and GDP binding in IBAT were increased two- to fourfold relative to that from long-photoperiod controls. Thus it appears that in Siberian hamsters the photoperiod-induced improvements in thermogenic capacity are mediated via the same mechanisms as are cold- or diet-induced thermogenesis.
 ...
PMID:Effects of diet and photoperiod on NE turnover and GDP binding in Siberian hamster brown adipose tissue. 395 50

The rate of oxygen consumption was measured in 2-day Zucker preobese (fa/fa), homozygous (Fa/Fa) lean, and lean rats of unknown genotype (Fa/?) over the ambient temperature range of 26-35 degrees C. Significant differences in body mass were found among the three groups at this early age, the preobese pups having the greatest body mass. To account for body mass differences, the oxygen consumption data were expressed in terms of metabolic body size (ml O2 consumed X g body mass-2/3 X h-1). This mass-independent rate of oxygen consumption was significantly lower in the preobese pups than in the homozygous lean (Fa/Fa) pups at both thermoneutral (33-34 degrees C) and cold (26-27 degrees C) ambient temperatures at which, respectively, minimal and maximal rates of oxygen consumption were observed. This reduction in energy expenditure occurs before the establishment of hyperphagia or decreased levels of activity in the preobese pups. These data support the view that attenuated energy expenditure is a significant contributor to the early development of obesity in the Zucker fatty rat and point to the possibility of defective brown adipose tissue-mediated thermogenesis in the preobese pup.
 ...
PMID:Energy expenditure is reduced in preobese 2-day Zucker fa/fa rats. 402 82

Two experiments were performed to determine if bilateral parasagittal hypothalamic knife-cuts (KCs), which produce long-term overeating and obesity, after biochemical indices of brown adipose tissue (BAT) reactivity to thermogenic stimuli. In the first study, responses to environmental cold were tested. Four weeks after surgery, KC rats had gained 4-5 times more weight than controls and were obese (increased Lee Obesity Index and weight of gonadal white fat). Before being sacrificed, groups of KC and control rats were exposed to 4 degrees C for 21 hr or remained at 28 degrees C. Interscapular BAT weighed 300% more in KC rats, due largely to increased white fat content. Functional indices of BAT thermogenic capacity (protein content, DNA content, cytochrome oxidase activity and mitochondrial guanosine diphosphate (GDP) binding) were normal at 28 degrees C. Exposure to 4 degrees C produced greatly enhanced responses but these were equivalent for both groups. This suggested an intact capacity for non-shivering thermogenesis in obese KC rats. In the second study, the same BAT responses were examined in other rats fed a palatable "cafeteria" diet (CAFE). One week after surgery, KC and control rats were subdivided into groups that received chow alone or chow plus four different palatable foods daily. Before sacrificing 4-5 weeks later, KC rats had gained 3-4 times more weight than controls and were obese. Interscapular BAT weighed 200-300% more in KC rats. CAFE feeding produced larger increments in all variables for KC vs. control rats. Most importantly, GDP binding was reduced in both KC groups, and significantly more so after CAFE feeding.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Impaired diet-induced thermogenesis in brown adipose tissue from rats made obese with parasagittal hypothalamic knife-cuts. 402 98

Male and female Holtzman rats were made hyperphagic and obese with bilateral radiofrequency heat lesions of the ventromedial hypothalamic (VMH) area. When VMH rats were maintained at 28 degrees C, their brown adipose tissue (BAT) DNA, protein, and cytochrome oxidase contents were normal although more stored lipid was present, as judged from a threefold increase in wet weight. Thermogenic activity of BAT mitochondria was normal in male VMH rats, as judged from the unchanged level of guanosine diphosphate (GDP) binding (known to be a sensitive index of the functional activity of the thermogenic proton conductance pathway), and reduced in female VMH rats. When rats with VMH lesions were exposed to cold (4 degrees C for 24 h), the visible hyperemia of their BAT and normal large increase in mitochondrial GDP binding indicated normal thermogenic responsiveness. We conclude that the medial nuclei of the hypothalamus and associated afferent or efferent nerve tracts do not represent an essential central nervous system link for cold-induced, sympathetic-mediated activation of BAT thermogenesis. It is possible, however, that diet-induced, sympathetic-mediated activation of BAT function and growth might require an intact VMH region because no enhancement of BAT mitochondrial function normally associated with hyperphagia was detected in these hyperphagic VMH-lesioned animals.
 ...
PMID:Brown adipose tissue of rats with obesity-inducing ventromedial hypothalamic lesions. 628 74

Young genetically obese (fatty, fa/fa) rats (7-8 wk old) maintained on a chow diet at 28 degrees C have a relatively normal amount of brown adipose tissue (BAT) (normal protein content, normal noradrenaline content, normal or slightly reduced cytochrome oxidase content, 30% reduction in DNA content) with cells grossly hypertrophied by accumulation of lipid. The binding of purine nucleotides by BAT mitochondria is lower in fa/fa rats than in lean rats, suggesting a lesser thermogenic activation of this tissue. Acute exposure to cold (24 h at 4 degrees C) activates BAT thermogenesis (visible hyperemia, marked increase in mitochondrial binding of purine nucleotides, depletion of noradrenaline content) in fa/fa rats as in lean rats. In contrast, feeding a cafeteria diet to young fa/fa rats fails to activate BAT (no increase in mitochondrial binding of purine nucleotides) as it does in lean rats, and these rats accumulate more extra fat (increase in weight of gonadal white adipose tissue) than do cafeteria diet-fed lean rats. It is concluded that the young fa/fa rat has normal cold-induced nonshivering thermogenesis in BAT but defective diet-induced thermogenesis in BAT and that the consequent reduction in energy expenditure, coupled with hyperphagia, contributes to the development of its obesity. The most probable location for the defect is suggested to be associated with the hypothalamus.
 ...
PMID:Brown adipose tissue in genetically obese (fa/fa) rats: response to cold and diet. 629 7

Gold thioglucose (GTG)-obese mice have a larger than normal amount of brown adipose tissue (BAT) with ultrastructurally normal mitochondria. The tissue grows normally when the mice adapt to cafeteria feeding or to cold (8 degrees C). Acute exposure to cold causes a fairly normal thermogenic activation of BAT mitochondria of GTG-obese mice, both in dynamic and static phases of their obesity. However, chow-fed GTG-obese mice have BAT mitochondria that are in a low state of thermogenic activation, and these mice fail to respond to eating a cafeteria diet for 3 wk by a normal thermogenic activation of their BAT mitochondria. More prolonged cafeteria feeding for 11-13 wk, into the static phase of obesity, is associated with thermogenic activation of BAT mitochondria of GTG-obese mice. The capacity of GTG-obese mice to respond to noradrenaline (norepinephrine) by an increase in metabolic rate is greater than that of lean mice and is further enhanced by cold acclimation. It is concluded that BAT of the GTG-obese mouse is inherently functional, as is control of its thermogenic function and growth during cold exposure and cold acclimation. Dietary influences on BAT thermogenic function are, however, defective in the GTG-obese mouse at least during the dynamic phase of its obesity. The resulting failure of diet-induced thermogenesis would be expected to contribute to the known high metabolic efficiency of the GTG-obese mouse and, together with the hyperphagia, to the obesity induced by GTG.
 ...
PMID:Brown adipose tissue of mice with gold thioglucose-induced obesity: effect of cold and diet. 640 32

Golden hamsters (Mesocricetus auratus) were subjected to intermittent fasting for six weeks, for three of which their environmental temperature was reduced to 4 degrees C. They were compared with a control group (fed ad libitum and kept at 22 degrees C), a group subjected six weeks only to intermittent fasting at 22 degrees C and a group fed ad libitum for six weeks, but exposed to a temperature of 4 degrees C after the third week. The effect of these various nutritional and temperature regimens on growth, on food consumption, on the formation of liver glycogen and lipid reserves and on energy metabolism was studied. Adaptation to cold raised the hamsters' food intake above the hyperphagia level observed during intermittent fasting. Cold and intermittent fasting acted synergically in raising basal oxygen consumption values and reducting the amount of body lipids. They acted antagonistically on the liver glycogen concentration; when they were used simultaneously, the effect of intermittent fasting preponderated.
 ...
PMID:Effect of intermittent fasting followed by cold on growth, formation of reserves and energy metabolism in the golden hamster. 644 98

Surgical denervation of the five sympathetic nerves supplying one lobe of the interscapular brown fat of control rats caused small reductions in mass, protein content and the activity of the thermogenic mitochondrial proton conductance pathway (assessed from guanosine-5'-diphosphate (GDP) binding) when compared to the intact lobe. Denervation did not affect the acute 100% increase in mitochondrial GDP binding capacity seen after a single injection of noradrenaline. Cold-adaptation (4 degrees C for 7 days) or over-feeding (cafeteria diet for 10 days) caused marked increases in the mass, protein content and specific mitochondrial GDP binding in intact brown adipose tissue, but these changes were totally prevented by surgical denervation. These data indicate that the hypertrophy and the increased thermogenic capacity of brown fat induced by cold-adaptation or hyperphagia depend entirely upon the sympathetic innervation of the tissue.
 ...
PMID:Effects of denervating brown adipose tissue on the responses to cold, hyperphagia and noradrenaline treatment in the rat. 649 99

A diurnal hyperphagia is certainly the main factor of adiposity in the genetically obese Zucker fa/fa rat. In a previous experiment it was observed that cold-acclimatization suppressed hyperphagia and stopped the increase in obesity. In this work, the chronology of modification in the feeding pattern is studied during the first month of cold exposure (10 degrees C). The main cold-induced modifications are observed after 2 weeks of cold exposure. Possibly the decrease in metabolic efficiency of food could parallel the cold-induced enhancement of energetic capacity of brown adipose tissue which has been described elsewhere. This tissue could play a role in the obesity of the Zucker rat.
 ...
PMID:[Effect of cold adaptation on the feeding behavior of genetically obese Zucker rats]. 652 85

Rats fed either a low (2p. 100) or high (40 p. 100)-fat diet were exposed to 22 or 5 degrees C. The resulting hyperphagia adequately compensated energy losses as judged from body weight. The cold-induced hyperphagia was accompanied by a non-parallel increase in pancreatic hydrolases. Amylase and lipase were not increased above the adaptive levels they had respectively reached in the heat with a high-starch or high-lipid diet. Chymotrypsinogen, on the contrary, responded to increased intake of both diets. It also responded to the higher protein concentration in the high-fat diet caused by isocaloric replacement of starch by fat. Colipase varied independently of lipase and was increased additively by fat and protein intakes. Consequently, although limiting for lipase in the warm, colipase rose to a 1:1 ratio in the cold. Increased intake had a consistent pleiotropic effect evidenced by an increase of amylase with the high-fat diet and of lipase with the low-fat diet. The net effect was a significant increase in the lipid-digesting potential of the organism of lipid-fed animals upon exposure to cold, while the starch-digesting potential remained unaffected in starch-fed animals.
 ...
PMID:Pancreatic hydrolases in cold-induced hyperphagia of rats fed a low or high-fat diet. 657 35


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