Angiotensin II in brown adipose tissue from young and adult Zucker obese and lean rats

1994 ◽  
Vol 266 (3) ◽  
pp. E453-E458 ◽  
Author(s):  
L. A. Cassis

Previous studies demonstrated that interscapular brown adipose tissue (ISBAT) produces angiotensin II (ANG II), which facilitates sympathetic neurotransmission (SN). ANG II content and regulation of SN were examined in young (17 days) and adult (16 wk) Zucker obese and lean rats. ANG II content in ISBAT from preobese rats was decreased compared with lean littermates. Evoked 3H overflow in ISBAT slices preloaded with [3H]NE was greater in preobese rats compared with control. ANG II increased evoked 3H overflow in ISBAT slices to a greater extent in preobese rats compared with control. [3H]NE uptake in ISBAT slices from preobese rats was decreased compared with control. In adult obese rats, plasma renin activity was decreased compared with control. ISBAT ANG II content was increased in adult obese rats compared with control. Evoked 3H overflow in ISBAT slices preloaded with [3H]NE was not different between obese and control. ANG II did not increase evoked 3H overflow in obese rats; however, ANG II increased evoked 3H overflow in lean rats. [3H]NE uptake in ISBAT slices from obese rats was decreased compared with control. These results suggest that ANG II modulation of SN activity is decreased in ISBAT from adult obese rats. In contrast, in young obese rats, increased SN activity and ANG II regulation of SN were evident in brown adipose tissue.

1985 ◽  
Vol 248 (1) ◽  
pp. E20-E25 ◽  
Author(s):  
M. Saito ◽  
Y. Minokoshi ◽  
T. Shimazu

The interscapular brown adipose tissue (IBAT) from obese rats with lesions of the ventromedial hypothalamus (VMH) was approximately 5 times heavier than those from controls. This hypertrophy of IBAT was associated with a marked enlargement of constituent adipocytes and their apparent transformation from multiloculated structure of lipid droplets into the uniloculated structure. The rate of fatty acid synthesis in IBAT of the obese rats was less than one-tenth of that in control rats and approximated the value in white adipose tissue (WAT) when they were starved for 24 h. When rats were fed, the synthetic rate was increased, but the lipogenic response of IBAT in the obese rats was much greater than that in controls, the extent of the response being comparable to that of WAT. The IBAT temperature rose rapidly on electrical stimulation of the sympathetic nerves to the tissue in control rats, whereas the temperature response was reduced markedly in the obese rats. It was suggested that thermogenesis in BAT was impaired in obese rats with VMH lesions by decreasing triglyceride turnover in BAT, probably due to dysfunction of the sympathetic nervous system and a consequent transformation of BAT into WAT.


1982 ◽  
Vol 47 (3) ◽  
pp. 653-658 ◽  
Author(s):  
E. Connolly ◽  
R. D. Morrisey ◽  
J. A. Carnie

1. The removal of the interscapular brown adipose tissue (IBAT) led to an increase in body-weight of normal, lean mice as compared to anaesthetized controls.2. No significant difference in food consumption could be detected between the two groups of mice over the period of the experiment.3. Fat extraction of the whole carcasses with chloroform: methanol showed a statistically significant increase in fat content in the animals without IBAT.4. There was no apparent failure in the operated animals to sustain core temperature when exposed to a cold stress situation (4° for 24 h).5. There was no difference in the wet weight, protein content or cytochrorne oxidase content of the dorso-cervical brown adipose tissue (DCBAT) between operated and control mice. This is indicative of a lack of proliferation of other brown adipose tissue sites in the operated mice in response to the removal of the IBAT.6. It is suggested that brown adipose tissue is implicated in dietary themiogenesis in the mouse.


1997 ◽  
Vol 272 (3) ◽  
pp. C989-C999 ◽  
Author(s):  
U. Shenoy ◽  
L. Cassis

Angiotensin (ANG) II plays a vital role in blood pressure regulation and body fluid homeostasis. Although many peripheral tissues synthesize components of the renin-ANG system, very few synthesize all of the major components involved in the generation ofANG II. This study used interscapular brown adipose tissue (ISBAT) as a model system to evaluate the mechanism of ANG II generation in an extrarenal tissue. Polymerase chain reaction analysis of DNA from ISBAT demonstrated angiotensinogen gene expression; however, renin gene expression was not detected. Renin activity that was not completely derived from the residual blood pool was detected in ISBAT homogenates. Kinetic parameters for renin activity were similar in ISBAT and adrenal gland. Renin activity was partially inhibited by anti-renin antibody and completely inhibited by a specific rat renin inhibitor. Bilateral nephrectomy did not decrease renin activity in ISBAT. Western blot analysis, employing two species-specific renin antibodies, indicated the presence of a variety of isoforms of renin in ISBAT. The presence of renin activity in isolated brown adipocytes demonstrated that the enzyme is localized to adipocytes. The release of immunoreactive ANG peptides from ISBAT slices over 3 h indicated de novo synthesis. These studies support the existence of a local renin-ANG system in ISBAT and suggest involvement of renin in the formation of ANG II.


1999 ◽  
Vol 276 (1) ◽  
pp. R143-R151 ◽  
Author(s):  
Victoria L. King ◽  
Linda P. Dwoskin ◽  
Lisa A. Cassis

The neuronal uptake of norepinephrine (NE) in sympathetically innervated tissues is mediated by a high-affinity NE uptake transporter (NET). Rat interscapular brown adipose tissue (ISBAT) is densely innervated by the sympathetic nervous system for the control of cold- and diet-induced thermogenesis. To determine if cold exposure regulates the NET, kinetic parameters for [3H]NE uptake and [3H]nisoxetine (Nis) binding were determined in ISBAT from 7-day cold-exposed (CE) and control rats. Uptake of [3H]NE in ISBAT slices was of high affinity (1.6 μM). After 7 days of cold exposure the affinity for [3H]NE uptake was not altered; however, the uptake capacity was decreased (38%) in ISBAT slices from CE rats. Kinetic parameters for [3H]Nis binding demonstrated a single high-affinity site in ISBAT from CE and control rats with similar affinity. The density of [3H]Nis sites in ISBAT was decreased (38%) following cold exposure. A time course (2 h-7 days) for cold exposure demonstrated downregulation of [3H]Nis binding density by day 3, which remained through day 7. The affinity for [3H]Nis binding was transiently decreased at 2 h of cold exposure. Similarly, ISBAT NE content was decreased at 2 h of cold exposure. Pair feeding CE rats to food intake of controls normalized plasma NE content; however, [3H]Nis binding density in ISBAT remained decreased in pair-fed rats. These results demonstrate that the ISBAT NET is downregulated following cold exposure. Reductions in ISBAT NE content precede alterations in NET density; however, plasma NE content is not related to regulation of the NET.


Metabolism ◽  
1987 ◽  
Vol 36 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Toshihide Yoshida ◽  
Hitoshi Nishioka ◽  
Keiji Yoshioka ◽  
Motoharu Kondo

1991 ◽  
Vol 260 (2) ◽  
pp. R278-R283 ◽  
Author(s):  
F. Assimacopoulos-Jeannet ◽  
M. Moinat ◽  
P. Muzzin ◽  
C. Colomb ◽  
B. Jeanrenaud ◽  
...  

The aim of the study was to examine in the obese Zucker (fa/fa) rats the effect of a peroxisome proliferator nafenopin on liver and brown adipose tissue peroxisomal and mitochondrial beta-oxidation enzyme activities and on the overall energy dissipation. A 17-day nafenopin treatment increased liver wet weight 2.1-fold and liver total acyl-CoA oxidase and mitochondria beta-oxidative activities 32- and 4.6-fold, respectively. It increased the interscapular brown adipose tissue (IBAT) acyl-CoA oxidase activity 2.1-fold but had no effect on the mitochondria beta-oxidative activity. Because nafenopin was found to decrease food intake by 22%, obese nafenopin-treated rats were compared with a group of obese pair-fed rats. Both food restriction and nafenopin treatment decreased body weight gain, but a decrease (14%) in fat content was only observed in nafenopin-treated rats. Food restriction of obese rats decreased the mean metabolic rate by 13%, and nafenopin treatment prevented this decrease. Both food restriction and nafenopin treatment decreased the mean daily respiratory quotient (RQ). However, the RQ of nafenopin-treated rats was steadily lower than that of control, whereas that of food-restricted rats was the same as that of control animals during the feeding period and decreased when food supply was exhausted. The increase in liver and IBAT fatty acid beta-oxidative activities may be the cause of the decreased lipid accretion measured in obese rats.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana Paula Christakis Costa ◽  
Joaquim Miguel Maia ◽  
Marcos Leal Brioschi ◽  
José Eduardo de Melo Mafra Machado

AbstractThis exploratory retrospective study aims to investigate the thermal changes in the thyroid gland region of patients with hypothyroidism and fibromyalgia by analyzing the temperature of the brown adipose tissue (BAT). A total of 166 individuals from 1000 thermographic electronic medical records were classified into four groups: Group HP + FM-50 individuals with hypothyroidism and fibromyalgia; Group FM-56 individuals with fibromyalgia only; Group HP-30 individuals with hypothyroidism only, and Group Control-30 healthy individuals. The thermal images from the electronic medical records were acquired by a FLIR T650SC infrared camera (used for thermometry) and the temperature data for each group were statistically analyzed. Group HP + FM showed r = 0, meaning that the average temperatures of the thyroid and BAT are independent of each other. Groups FM, HP and Control showed r = 1, meaning that the average temperatures of the thyroid and BAT were directly related. Our findings showed that the average temperatures of the thyroid and BAT regions are similar. Also, there was no correlation between thyroid gland temperature and the presence of hypothyroidism or fibromyalgia using thermometry.


1992 ◽  
Vol 282 (1) ◽  
pp. 231-235 ◽  
Author(s):  
D M Smith ◽  
S R Bloom ◽  
M C Sugden ◽  
M J Holness

Starvation (48 h) decreased the concentration of mRNA of the insulin-responsive glucose transporter isoform (GLUT 4) in interscapular brown adipose tissue (IBAT) (56%) and tibialis anterior (10%). Despite dramatic [7-fold (tibialis anterior) and 40-fold (IBAT)] increases in glucose utilization after 2 and 4 h of chow re-feeding, no significant changes in GLUT 4 mRNA concentration were observed in these tissues over this re-feeding period. The results exclude changes in GLUT 4 mRNA concentration in mediating the responses of glucose transport in these tissues to acute re-feeding after prolonged starvation.


1991 ◽  
Vol 277 (3) ◽  
pp. 625-629 ◽  
Author(s):  
J P Revelli ◽  
R Pescini ◽  
P Muzzin ◽  
J Seydoux ◽  
M G Fitzgerald ◽  
...  

The aim of the present work was to study the effect of hypothyroidism on the expression of the beta-adrenergic receptor (beta-AR) in interscapular brown adipose tissue and heart. The total density of plasma membrane beta-AR per tissue is decreased by 44% in hypothyroid rat interscapular brown adipose tissue and by 55% in hypothyroid rat heart compared with euthyroid controls. The effects of hypothyroidism on the density of both beta 1- and beta 2-AR subtypes were also determined in competition displacement experiments. The densities of beta 1- and beta 2-AR per tissue are decreased by 50% and 48% respectively in interscapular brown adipose tissue and by 52% and 54% in the heart. Northern blot analysis of poly(A)+ RNA from hypothyroid rat interscapular brown adipose tissue demonstrated that the levels of beta 1- and beta 2-AR mRNA per tissue are decreased by 73% and 58% respectively, whereas in hypothyroid heart, only the beta 1-AR mRNA is decreased, by 43%. The effect of hypothyroidism on the beta 1-AR mRNA is significantly more marked in the interscapular brown adipose tissue than in the heart. These results indicate that beta-AR mRNA levels are differentially regulated in rat interscapular brown adipose tissue and heart, and suggest that the decrease in beta-AR number in interscapular brown adipose tissue and heart of hypothyroid animals may in part be explained by a decreased steady-state level of beta-AR mRNA.


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