Brown Adipose Tissue Blood Flow and Mass in Obesity: A Contrast Ultrasound Study in Mice

1. The warmest interscapular skin areas were located by thermography in six healthy subjects during ephedrine-induced thermogenesis. 2. In these interscapular areas, and in lumbar control areas, the skin temperature, subcutaneous temperature and adipose tissue blood flow were measured before and during ephedrine-induced thermogenesis. 3. The skin and subcutaneous temperatures increased in the interscapular area as well as in the lumbar area, by about 0.7-1.2°C. The interscapular skin temperature remained about 1°C higher than the lumbar; the subcutaneous temperatures in the two areas were identical during the experiments. 4. Although the interscapular subcutaneous adipose tissue blood flow increased about sixfold and the lumbar increased twofold, the absolute flows were higher in the lumbar area. 5. The oxygen uptake increased to a maximum of 30% above control level. 6. Plasma glucose and glycerol concentrations remained unchanged, and plasma non-esterified fatty acids, lactate and noradrenaline concentrations increased slightly but significantly. 7. Biopsies taken from the hot interscapular areas did not contain brown adipose tissue. 8. It is concluded that the high interscapular skin temperature may be due to a lower insulating fat thickness and that the increases in skin and subcutaneous temperatures during ephedrine-induced thermogenesis are caused by an increased blood flow. These observations weigh against the hypothesis that the interscapular temperature increase is due to functional, interscapular brown adipose tissue.

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Brown adipose tissue, liver, and diet-induced thermogenesis in cafeteria diet-fed rats

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y89-061 ◽

1989 ◽

Vol 67 (4) ◽

pp. 376-381 ◽

Cited By ~ 30

Author(s):

Stephanie W. Y. Ma ◽

David O. Foster

Keyword(s):

Blood Flow ◽

Adipose Tissue ◽

Brown Adipose Tissue ◽

Direct Determination ◽

Metabolizable Energy ◽

Whole Body ◽

Tissue Blood Flow ◽

Direct Measurements ◽

Brown Adipose ◽

Diet Induced Thermogenesis

Diet-induced thermogenesis (DIT) in young rats overeating a "cafeteria" (CAF) diet of palatable human foods is characterized by a chronic, propranolol-inhibitable elevation in resting metabolic rate [Formula: see text] and is associated with various changes in brown adipose tissue (BAT) that have been taken as evidence for BAT as the effector of DIT. But direct evidence for participation of BAT in DIT has been lacking. By employing a nonocclusive cannula to sample the venous effluent of interscapular BAT (IBAT) for analysis of its O2 content and measuring tissue blood flow with microspheres, we accomplished direct determination (Fick principle) of the O2 consumption of BAT in conscious CAF rats. In comparison with normophagic controls fed chow, the CAF rats exhibited a 43% increase in metabolizable energy intake, reduced food efficiency, a 22% elevation in resting [Formula: see text] at 28 °C (thermoneutrality) or 24 °C (housing temperature), and characteristic changes in the properties of their BAT (e.g., increased mass, protein content and mitochondrial GDP binding). They also exhibited the greater metabolic response to exogenous noradrenaline characteristic of CAF rats and the near elimination by propranolol of their elevation in [Formula: see text]. By the criterion of their elevated [Formula: see text], the CAF rats were exhibiting DIT at the time of the measurements of BAT blood flow and blood O2 levels. However, BAT O2 consumption was found to be no greater in the CAF rats than in the controls at either 28 or 24 °C. At 28 °C it accounted for less than 1% of whole body [Formula: see text]; at 24 °C it increased to about 10% of overall [Formula: see text] in both diet groups. Direct measurements of BAT O2 consumption during expression of the thermic response to a tube-fed meal were also made in conscious CAF and control rats. Both diet groups exhibited an approximately 15% increase in whole body [Formula: see text] at 90–120 min after the meal. The contribution by BAT to this increase was only 2–3% and did not differ significantly between groups. Thus, the results of these direct measurements of BAT O2 consumption in vivo do not support the theory that DIT in CAF rats is mainly due to increased BAT thermogenesis occurring either chronically or during assimilation of a meal. In further studies of the effector(s) of DIT in CAF rats, partial hepatectomy (two-thirds of the liver removed) was found to acutely reduce the resting [Formula: see text] of CAF rats by 1.85 mL/min, 2.3 times as much as in chow-fed controls. From this difference in response, it was estimated that in the CAF rats liver O2 consumption before hepatectomy exceeded that of the controls by about 1.5 mL/min, an amount that would be sufficient to fully account for the elevation in resting [Formula: see text] of the former. A major role for the liver in the DIT of CAF rats is thus suggested.Key words: cafeteria feeding, diet-induced thermogenesis, thermic effect of food, brown fat, liver.

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Thermogenic effects of dihydrocodeine in the rat

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y88-011 ◽

1988 ◽

Vol 66 (1) ◽

pp. 61-65 ◽

Cited By ~ 1

Author(s):

Nancy J. Rothwell ◽

Michael J. Stock ◽

Alison E. Tedstone

Keyword(s):

Blood Flow ◽

Adipose Tissue ◽

Oxygen Consumption ◽

Brown Adipose Tissue ◽

Opiate Receptors ◽

Zucker Rats ◽

Tissue Blood Flow ◽

Dependent Manner ◽

Brown Adipose ◽

Adrenergic Antagonist

The object of this study was to assess the effects of dihydrocodeine on thermogenesis and brown adipose tissue activity in the rat from measurements of oxygen consumption and blood flow. Acute injection of dihydrocodeine tartrate (s.c.) stimulated resting oxygen consumption [Formula: see text] in Sprague–Dawley rats in a dose-dependent manner (0.5–50 mg/kg), with a peak response (40–45% increase) occurring at 10–25 mg/kg. This effect was also observed in urethane-anaesthetized rats (although the effect was reduced) and in conscious animals following gastric intubation with the drug. Pretreatment of rats with either a β-adrenergic antagonist (propranolol, 20 mg/kg), ACTH (4 g/kg), or an opiate antagonist (WIN44441-1, 2 mg/kg) significantly reduced the response to dihydrocodeine, whereas corticosterone injection (5 mg/kg) enhanced the effect. Surgical adrenalectomy or hypophysectomy (HYPX) almost completely abolished the thermogenic effect of dihydrocodeine. Dihydrocodeine also stimulated [Formula: see text] in lean (58% increase) and genetically obese Zucker rats (69% increase), and in both Zucker genotypes these responses were only slightly affected by HYPX, but enhanced in HYPX rats treated daily with corticosterone (1 mg/kg). Tissue blood flow, assessed from the distribution of radiolabelled microspheres, was unaffected in white adipose tissue, skeletal muscle, testes, kidney, brain, and liver (arterial supply) after a single injection of dihydrocodeine (25 mg/kg), but flow to interscapular and perirenal brown adipose tissue was increased by 9- to 10-fold. Surgical sympathectomy of brown adipose tissue prevented the increase in blood flow. These potent thermogenic effects of dihydrocodeine in the rat appear to result from sympathetic activation of heat production in brown fat and to involve opiate receptors, but can also be modified by pituitary and (or) adrenal hormones.

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Reversal of high pancreatic islet and white adipose tissue blood flow in type 2 diabetic GK rats by administration of the β3-adrenoceptor inhibitor SR-59230A

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00140.2009 ◽

2009 ◽

Vol 297 (2) ◽

pp. E490-E494 ◽

Cited By ~ 13

Author(s):

U. S. Pettersson ◽

J. Henriksnäs ◽

L. Jansson

Keyword(s):

Blood Flow ◽

Adipose Tissue ◽

Tissue Blood Flow ◽

Pancreatic Blood Flow ◽

Gk Rat ◽

Gk Rats ◽

Brown Adipose ◽

Adipose Tissue Blood Flow ◽

Increased Blood Flow

Previous studies have shown that the Goto-Kakizaki (GK) rat, a nonobese type 2 diabetes model, has an increased white adipose tissue (WAT) and islet blood flow when compared with control rats. The aim of the study was to examine if these increased blood flow values in GK rats could be affected by the β3-adrenoceptor antagonist SR-59230A. We measured organ blood flow with a microsphere technique 10 min after administration of SR-59230A (1 mg/kg body wt), or the corresponding volume of 0.9% NaCl solution (1 ml/kg body wt) in rats anaesthetized with thiobutabarbital. The GK rat had an increased blood flow in all intra-abdominal adipose tissue depots except for the sternal fat pad compared with Wistar-Furth (WF) rats. However, no differences were seen in the blood perfusion of subcutaneous white or brown adipose tissue. The blood flow was also increased in both the pancreas and in the islets in the GK rat compared with WF rats. SR-59230A treatment affected neither WAT nor pancreatic blood flow in WF rats. In GK rats, on the other hand, SR-59230A decreased both WAT and islet blood flow values to values similar to those seen in control WF rats. The whole pancreatic blood flow was not affected by SR-59230A administration in GK rats. Interestingly, the brown adipose tissue blood flow in GK rats increased after SR-59230A administration. These results suggest that β3-adrenoceptors are involved in regulation of blood flow both in islet and in adipose tissue.

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Tissue distribution of cold-induced thermogenesis in conscious warm- or cold-acclimated rats reevaluated from changes in tissue blood flow: The dominant role of brown adipose tissue in the replacement of shivering by nonshivering thermogenesis

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y79-039 ◽

1979 ◽

Vol 57 (3) ◽

pp. 257-270 ◽

Cited By ~ 351

Author(s):

David O. Foster ◽

M. Lorraine Frydman

Keyword(s):

Blood Flow ◽

Adipose Tissue ◽

Brown Adipose Tissue ◽

Tissue Distribution ◽

Cold Exposure ◽

Tissue Blood Flow ◽

Anatomical Site ◽

Nonshivering Thermogenesis ◽

White Rats ◽

Brown Adipose

Radioactive microspheres (12–16 μm) were used to measure cardiac output (CO), its fractional distribution, and hence tissue blood flow in conscious, warm-acclimated (WA) or cold-acclimated (CA) white rats exposed to temperatures of 25, 21, 6, −6, and −19 °C, the objective being to assess the tissue distribution of cold-induced thermogenesis. Total oxygen consumption was also measured. CA rats at 25 °C (CA25) had elevated arteriovenous shunting and other signs of heat stress. CA21 proved more suitable controls for the CA group. The cold-induced changes in blood flow to total skeletal muscle not involved in respiratory movements (M) and to the major masses of brown adipose tissue (BAT) were quantitatively very different in the two acclimation groups: in WA25 and CA21 flows to M were 31 (0.24 CO) and 27 (0.17 CO) mL/min, respectively, while flows to BAT were 2.1 and 9.7 mL/min; in WA−19 and CA−19 flows to M were 62 (0.32 CO) and 35 (0.16 CO) mL/min, respectively, while flows to BAT were 25 and 56 mL/min. In contrast, the effects of cold exposure on flows to other tissues and organs were remarkably alike in the two acclimation groups: e.g., flows to heart, ribcage, and diaphragm increased about three times between 25 and −19 °C, flow to the skin fell about 50%, and flows to the hepatosplanchnic region and kidneys were little or not at all affected by cold exposure. Estimates of the contributions of different tissues and organs to cold-induced thermogenesis were made on the basis of the relative changes in blood flow. It is concluded that BAT is by far the dominant anatomical site of the increased heat production of cold-exposed CA rats, and that nonshivering thermogenesis in BAT supplements considerably the shivering thermogenesis of cold-exposed WA rats.

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Evidence for a contribution by brown adipose tissue to the development of fever in the young rabbit

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y85-099 ◽

1985 ◽

Vol 63 (6) ◽

pp. 595-598 ◽

Cited By ~ 19

Author(s):

W. H. Harris ◽

D. O. Foster ◽

B. E. Nadeau

Keyword(s):

Blood Flow ◽

Adipose Tissue ◽

Brown Adipose Tissue ◽

Heat Production ◽

Brown Fat ◽

Young Rabbit ◽

Tissue Blood Flow ◽

Febrile Response ◽

Arterial Blood ◽

Brown Adipose

This study was undertaken to determine if brown adipose tissue was involved in heat production during fever produced by S. abortus equi (1 μg) in unanesthetized rabbits aged 19–26 days. The fever (0.9–1.6 °C) occurred after a delay of 20–30 min and was frequently biphasic. Radiolabelled microspheres for measuring tissue blood flow were injected intraventricularly into three groups of animals: rabbits not given pyrogen, rabbits in which the febrile response to pyrogen was developing, and rabbits in which the febrile response had peaked. Blood flow to brown fat deposits and other organs was calculated from the fractional distribution of the microspheres and the recovery of microspheres in a reference arterial blood sample. At the fever peak, blood flow to brown fat was not significantly different (p > 0.05) from the control value (0.9 ± 0.2), but during the rising phase of the fever the flow increased significantly (p < 0.01) to 2.6 ± 0.4 mL min−1 g−1. The blood flow to muscles of the forelimbs and hind limbs was also increased significantly (p < 0.05) during the rising phase of the fever. No significant change in blood flow to other organs or tissues was found during the rising phase of the fever. These results indicate that both nonshivering as well as shivering thermogenesis contribute to heat production during development of fever in the young rabbit. However, nonshivering thermogenesis was not involved in the maintenance of the elevated body temperature after the fever had peaked.

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