Control of white and brown adipose tissues by the autonomic nervous system.
Explore the source record for details and available documents.
Adipose Tissue↗
Biomedical subjects
M Ashwell
Publications and source records attributed to M Ashwell.
Effect of warm or cold exposure on GDP binding and uncoupling protein in rat brown fat.
The effects of acute and chronic exposure to different environmental temperatures on the total tissue cytochrome oxidase activity, level of mitochondrial GDP binding, and specific mitochondrial concentration of uncoupling protein have been investigated in rat brown adipose tissue, a radioimmunoassay being used to measure uncoupling protein. Acclimation at different temperatures for 3 wk produced parallel changes in GDP binding, the concentration of uncoupling protein, and the activity of cytochrome oxidase, each parameter rising with decreasing temperature between thermoneutrality (29 degrees C) and 4 degrees C. Acute exposure of warm-acclimated (29 degrees C) rats to the cold (4 degrees C) led to a rapid increase in GDP binding without any alteration in the amount of uncoupling protein. The increase in binding was accompanied by an increase in the rate of acetate-induced swelling of the mitochondria. The concentration of uncoupling protein in warm-acclimated rats was significantly raised only after 48 h exposure to cold. When cold-acclimated rats were exposed acutely to the warm, there was a rapid decrease in GDP binding without any alteration in the amount of uncoupling protein. It is concluded that after alterations in environmental temperature the concentration of uncoupling protein in brown adipose tissue mitochondria changes much more slowly than GDP binding and that binding can therefore be dissociated from the amount of the protein.
Acclimatization↗
Pre- and postnatal development of adipose tissue at four sites in the guinea pig: effect of maternal diet restriction during the second half of pregnancy.
The effect of maternal diet restriction on the subsequent development of four adipose tissue depots has been studied in the guinea pig. Fetuses taken from, and pups born to, pregnant sows fed ad libitum (AL) displayed an increase in fat pad mass and in fat cell mass with increasing body mass at the four selected depots (interscapular (IS), retroperitoneal (RP), groin side subcutaneous (GS) and behind arm subcutaneous (BA)). The effect of maternal diet restriction (50% AL rations during the second half of pregnancy) was to significantly reduce the body masses at birth of the pups. The masses of the BA and GS fat pads and the mass of fat cells in the depots were reduced accordingly. However, the fat depot masses and fat cell masses of the IS and RP fat pads were larger than those of pups of comparable body mass born to AL fed sows. Diet restriction during the second half of pregnancy exerted preferential 'sparing' effects on the 'thermogenic' adipose tissue depots (IS and RP) suggesting the possibility that 'thermogenic' adipose tissue is more likely to be 'programmed' earlier in pregnancy than 'storage adipose tissue' (BA and GS).
Adipose Tissue↗
Immunological, histological and biochemical assessment of brown adipose tissue activity in neonatal, control and beta-stimulant-treated adult dogs.
Significant levels of mitochondrial uncoupling protein were demonstrated on neonatal dog mitochondria prepared from perirenal, bladder and subcutaneous adipose tissue sites. The protein was not detected in homogenates of adipose tissue samples from the same sites in adult, control dogs. However, chronic treatment of adult dogs with a beta-stimulant (LY 79730) led to the appearance of detectable amounts of uncoupling protein in perirenal and bladder but not subcutaneous adipose tissue depots. Decreases in mean cell diameter, increases in the frequency of multilocular cells and of cytochrome oxidase and creatine kinase were also associated with the effects of treatment on dog adipose tissue. The results demonstrate the age-related decline in dog brown adipose tissue and its reversal by chronic treatment with beta-stimulant.
2-Hydroxyphenethylamine↗
Brown adipose tissue triacylglycerol fatty acids of obese and lean mice: in situ and in transplants.
The triacylglycerols of white adipose tissue (WAT) from animals with high rates of lipogenesis, such as obese hyperglycemic mice or hypothalamically lesioned rats, contain high proportions of palmitoleic acid (16:1) and low proportions of linoleic acid (18:2). These differences appear to result from dilution of dietary 18:2 by synthesized fatty acids, particularly 16:1. To test this we have investigated the triacylglycerol fatty acid composition of brown and white adipose tissue of lean and obese mice, as brown adipose tissue (BAT) has a higher lipogenic rate than WAT and lipogenesis is faster in obese than in lean mice. Between three and eight weeks of age the proportions of fatty acids in the tissues changed, with a marked fall in milk-derived lauric and myristic acids. From 8 to 16 weeks they were more stable and the proportions of 16:1 and 18:2 in the different tissues were as expected, with the highest and lowest proportions, respectively, in BAT from obese mice. When BAT from obese mice was transplanted under the kidney capsule of lean mice, or vice versa, for one month, the fatty acid composition of the grafts changed toward that of the host BAT. The proportions of 18:2 and, to a lesser extent, 16:1 were slightly higher in the grafts than in the hosts but since this also occurred in lean-to-lean and obese-to-obese grafts it was probably a transplantation artifact. Overall, the results confirm that the physiological environment, rather than the source of the adipose tissue, is the major determinant of its fatty acid composition.
Adipose Tissue↗
The Nutrition Society in the 1980s: the questionnaire analysis.
Explore the source record for details and available documents.
Attitude↗
Brown adipose tissue: contributions of nature and nurture to the obesity of an obese mutant mouse (ob/ob).
The aim of this investigation was to compare the contributions of the genotype of the brown adipose tissue (BAT) and of its environment to the obesity of the mutant mouse C57 BL/6J ob/ob. Pieces of interscapular BAT from lean or obese mice were transplanted to a site underneath the kidney capsule of recipient lean or obese mice. The grafts were left in place for 6 to 12 weeks and then examined by histological methods by electron microscopy to examine the ultrastructure of the mitochondria and by fluorescence histochemistry to examine the catecholaminergic innervation of the grafts. When lean BAT was grafted into obese mice, or when obese BAT was grafted into lean mice, kept at ambient temperatures, the characteristics of the donor BAT (i.e. lipid droplet size, mitochondrial ultrastructure and catecholaminergic innervation) transformed partially, but not completely, towards those of BAT in the host mouse. However, if lean mice containing obese BAT grafts were cold-acclimated at 4 degrees C or obese mice containing lean BAT grafts were warm-acclimated at 33 degrees C, the characteristics of the donor BAT transformed completely towards those of the BAT in the host mouse. This complete transformation occurred even if the host mice were returned to 23 degrees C after the period of temperature acclimation. Fluorescent histochemical observations indicated that the sympathetic innervation of BAT grafts was only indistinguishable from that of the lean or obese host BAT when the mice received a period of temperature acclimation (cold for lean mice; warm for obese mice). We conclude that BAT grafts from lean mice can assume the typical characteristics of BAT in obese hosts and that BAT grafts from obese mice can assume the typical characteristics of BAT in lean hosts provided that both the sympathetic innervation and the vascularization of the grafts is the same as in the host. Intrinsic properties of BAT in genetically obese mice are therefore unlikely to be of paramount importance in determining the obesity of the ob/ob mouse. Our results support the conclusions of other workers in implicating the low activity of the sympathetic innervation of BAT as being crucially important in causing the reduction of thermogenic activity.
Acclimatization↗
Obesity: new insight into the anthropometric classification of fat distribution shown by computed tomography.
Twenty eight women presenting for routine computed tomography had their waist, hip, and thigh circumferences measured. The ratio of the area of intra-abdominal fat to the area of subcutaneous fat shown in the computed tomogram taken at the umbilical level was calculated and found to correlate highly significantly with the ratio of waist to hip circumference. The correlation between these two ratios remained significant after allowing for the degree of obesity (weight (kg)/height (m)2) and age. In contrast, there was no significant correlation between the ratio of intra-abdominal to subcutaneous fat and degree of obesity. A high ratio of waist to hip circumference has been shown to be associated with a high proportion of intra-abdominal fat. Thus women with a centralised distribution of fat (high waist to hip ratio: "apples") tend to have a greater proportion of their fat in the intra-abdominal depot than do women with a peripheral fat distribution (low waist to hip ratio: "pears"). The metabolic complications of obesity, which are associated with a high ratio of waist to hip circumference, may therefore relate specifically to the amount of intra-abdominal fat.
Adult↗
Measurement by radioimmunoassay of the mitochondrial uncoupling protein from brown adipose tissue of obese (ob/ob) mice and Zucker (fa/fa) rats at different ages.
The concentration of the 'uncoupling protein' in brown adipose tissue mitochondria has been measured in lean and obese (ob/ob) mice and Zucker (fa/fa) rats at different ages using a specific radioimmunoassay. During the suckling period the concentration of the protein was similar in normal and mutant animals of both types, despite the decrease in mitochondrial GDP binding observed in the obese. The concentration of uncoupling protein was, however, decreased in adult ob/ob mice and adult Zucker rats compared with their respective lean siblings, in parallel with the decrease in GDP binding. It is concluded that there is a 'masked', or inactive, form of uncoupling protein in young ob/ob mice and fa/fa rats.
Adaptation, Physiological↗
Fluorescent histochemical demonstration of catecholamines in brown adipose tissue from obese (ob/ob) and lean mice acclimated at different temperatures.
Fluorescent histochemistry was used to visualize catecholamines in brown adipose tissue (BAT) of lean and genetically obese mice after they had been acclimated at different temperatures. At all temperatures, strong catecholamine-dependent fluorescence, attributable to the sympathetic innervation, was seen around the blood vessels of BAT from both lean and obese animals. Additionally, catecholamine-dependent fluorescent varicosities, in direct contact with the adipocytes were seen in abundance in lean mice acclimated at 23 degrees, 13 degrees or 4 degrees C and in obese mice acclimated at 13 degrees C. This latter compartment was greatly reduced in lean mice acclimated at 33 degrees C and in obese mice acclimated at 23 degrees and 33 degrees C. Three acute treatments (pretreatment with a monoamine oxidase inhibitor; 24 h food deprivation; and short-term cold exposure followed by short-term warm exposure) all increased the varicose fluorescence associated with adipocytes in obese mice housed at 23 degrees C, which suggests that the low resting level in these animals is attributable, at least in part, to subthreshold concentrations of catecholamines in existing varicosities rather than the absence of sympathetic varicosities per se. These results are in accordance with the results from noradrenaline turnover studies which suggest that the difference in sympathetic nervous system (SNS) activity in BAT from lean and obese (ob/ob) mice is best demonstrated at normal environmental temperatures. The reduced SNS activity in BAT of obese mice (which our studies show to be at the 'cellular' level) is likely to be a major factor in their reduced non-shivering thermogenesis and resultant high efficiency of energy storage as previously suggested by other workers.
Acclimatization↗
The use of the adipose tissue transplantation technique to demonstrate that abnormalities in the adipose tissue metabolism of genetically obese mice are due to extrinsic rather than intrinsic factors.
Adipose tissue transplantation between genetically obese mice and their lean counterparts using the kidney capsule as the transplantation site has shown that the abnormally large fat cells of obese mice normalize in size when they are placed into a 'lean' environment. Furthermore, the abnormal fatty acid composition of the white adipose tissue of obese mice (higher proportion of palmitoleic acid and lower proportion of linoleic acid compared with lean) normalizes on transplantation into a 'lean' environment. Such experiments lead us to conclude that the differences in the lipolytic and lipogenic enzymes in the adipose tissue of genetically obese mice must be due to extrinsic factors rather than factors intrinsic to the adipocyte.
Adipose Tissue↗
Brown adipose tissue in the parametrial fat pad of the mouse.
Cold acclimation has been shown to produce a substantial increase in the number of brown adipocytes in the parametrial fat pad of female BALB/c mice-a site normally thought to consist of typical white adipocytes. The brown adipocytes have been identified not only on the basis of their morphology using light and electron microscopy, but also on the basis of the content of the mitochondrial 'uncoupling protein' (Mr = 32000) which is characteristic of the proton conductance pathway of brown adipose tissue.
Adipose Tissue↗
Effect of acclimation temperature on the concentration of the mitochondrial 'uncoupling' protein measured by radioimmunoassay in mouse brown adipose tissue.
The effect of acclimation temperature on the concentration of the mitochondrial 'uncoupling' protein (Mr 32000) from brown adipose tissue of mice has been investigated. The uncoupling protein was measured by a specific radioimmunoassay. Between 33 degrees C (thermoneutrality) and -2 degrees C there was a progressive increase with decreasing environmental temperature in the amount of uncoupling protein. For mice at -2 degrees C the mitochondrial concentration of the protein was 9-times higher than at 33 degrees C, while the total amount of the protein in interscapular brown adipose tissue was estimated to be nearly 80-times greater at -2 degrees C compared to 33 degrees C.
Acclimatization↗
Adaptive changes in the concentration of the mitochondrial 'uncoupling' protein in brown adipose tissue of hamsters acclimated at different temperatures.
The effect of acclimation at different temperatures on the activity of interscapular brown adipose tissue has been investigated in the hamster, a hibernator. Between 31 degrees and 4 degrees C the cytochrome oxidase activity of the tissue increased 4- to 5-fold, mitochondrial GDP binding per mg of mitochondrial protein doubled, and the amount of uncoupling protein rose from 1.7% to 5.4% of total mitochondrial protein. It is concluded that there are clear adaptive changes induced by temperature in brown adipose tissue of the hamster, but the changes are limited in comparison with those in the mouse.
Acclimatization↗
Measurement of rat brown-adipose-tissue mitochondrial uncoupling protein by radioimmunoassay: increased concentration after cold acclimation.
A specific antiserum has been raised against the 32 000-mol.wt. uncoupling protein from the mitochondria of rat brown adipose tissue and a sensitive radioimmunoassay for the protein has been developed. The uncoupling protein is present in large amounts in brown adipose tissue; its concentration is increased substantially by cold acclimation. The protein has not been detected in the liver, heart, or parametrial white adipose tissue of rats.
Adaptation, Physiological↗
Fatty acid composition of triglycerides from adipose tissue transplanted between obese and lean mice.
The subcutaneous adipose tissue of genetically obese mice (ob/ob) differs from that of lean littermates not only by virtue of its larger cells but also in its fatty acid composition; it contains a higher proportion of palmitoleic acid and a lower proportion of linoleic acid. To determine whether these differences in fatty acid composition were inherent in fat cells, subcutaneous adipose tissue from obese and lean mice was transplanted under the kidney capsules of lean and obese host mice and the fatty acid composition of the neutral lipids of the graft and of the host perirenal and subcutaneous fat was determined 1 or 2 months later. The fatty acid composition of grafts from lean donors in obese mice resembled that of the perirenal adipose tissue of the obese hosts after 1 month, with a lower proportion of linoleic acid and a higher proportion of palmitoleic acid than in lean mice. Grafts from obese mice in lean mice had fatty acid compositions which were either unchanged, partially changed or which completely resembled that of the host. The use of grafts prelabeled by feeding the donor margaric acid indicated that total lack of fatty acid turnover, rather than selective metabolic processes, was responsible for the failure of some grafts from obese mice in lean mice to acquire the fatty acid composition of the perirenal adipose tissue of the host.
Adipose Tissue↗
Brown adipose tissue--relevant to obesity? A report of a meeting held by the Association for the Study of Obesity, 25 November, 1982.
Explore the source record for details and available documents.
Adipose Tissue, Brown↗
Female fat distribution-a simple classification based on two circumference measurements.
An alternative to the fat distribution (FD) score based on photographic measurements is constructed by discriminant analysis based on waist and thigh circumferences: Fat distribution (circumference) score (CFD score) = 29 log10 (waist circumference-36 log10 (thigh circumference)+10.5. The CFD score shows a correlation of 0.88 with the FD score over 54 female subjects, and can be used instead of, but not interchangeably with, the FD score to classify female fat distribution.
Adipose Tissue↗