cAMP metabolism and lipolysis in brown adipocytes of hamsters consuming a cafeteria diet

1985 ◽  
Vol 248 (2) ◽  
pp. E224-E229
Author(s):  
R. J. Schimmel ◽  
L. McCarthy ◽  
K. K. McMahon
Keyword(s):  
Adenylate Cyclase ◽  
Sympathetic Activity ◽  
Brown Fat ◽  
Adenylate Cyclase System ◽  
Brown Adipocytes ◽  
Beta Adrenergic ◽  
Fat Depots ◽  
Brown Adipose ◽  
Camp Levels ◽  
In Cells

Feeding animals cafeteria diets causes increased sympathetic activity to brown adipose tissue and this is believed to be responsible for the concomitant activation of thermogenesis. Because chronic catecholamine stimulation in other systems leads to a desensitization of beta-adrenergic receptors, we examined lipolysis and cAMP production in brown adipocytes of hamsters eating cafeteria diets for evidence of diminished beta-adrenergic responses. Basal cAMP levels were similar in chow- and cafeteria-fed hamsters. However, adipocytes from overfed animals formed less cAMP in response to isoproterenol than those of control animals. Isoproterenol-stimulated adenylate cyclase activity was similarly decreased in membrane preparations from cafeteria-fed hamsters. However, when the diterpene forskolin was used, equal amounts of cAMP were formed in cells and membrane preparations from control and overfed animals. In contrast to the reduced responses of the cAMP system to isoproterenol stimulation observed in overfed hamsters, isoproterenol-stimulated lipolysis was greater in cells from overfed animals than in cells from control animals. These results are consistent with a desensitization of the adenylate cyclase system in brown adipocytes occurring during chronic hyperphagia. Because eating cafeteria diets has been reported to increase sympathetic activity to brown fat depots, the apparent desensitization of brown adipocytes observed in this study may result from a persistent stimulation of the brown fat with norepinephrine in vivo. Our data also suggest the existence of mechanisms that preserve lipolysis in the face of low cAMP levels.

Adenylate cyclase agonist properties of CGP-12177A in brown fat: evidence for atypical beta-adrenergic receptors

1991 ◽  
Vol 260 (2) ◽  
pp. E226-E231
Author(s):  
P. J. Scarpace ◽  
M. Matheny
Keyword(s):  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Dependent Manner ◽  
Beta Adrenergic ◽  
Brown Adipose ◽  
Adrenergic Antagonist ◽  
Dose Dependent ◽  
Binding Curves

Thermogenesis in brown adipose tissue (BAT) is stimulated by catecholamine activation of adenylate cyclase through the beta-adrenergic receptor. Recently it was reported that the beta-adrenergic antagonist CGP-12177A stimulates oxygen consumption in BAT. To investigate the mechanism of action of CGP-12177A in BAT, we assessed the inhibitory and stimulatory affects of CGP-12177A on the adenylate cyclase system in myocardial and BAT membranes from rats. CGP-1277A inhibited isoproterenol-stimulated adenylate cyclase activity in a dose-dependent manner, with an inhibitory constant (Ki) of 1.94 +/- 0.18 microM in BAT and 0.49 +/- 0.11 microM in the heart. However, in the absence of isoproterenol, CGP-12177A stimulated adenylate cyclase in BAT with two components of activation, and half-maximal stimulation occurred at 1 microM and 1.5 mM. In contrast, CGP-12177A did not stimulate adenylate cyclase activity in heart membranes. Propranolol inhibited the isoproterenol-stimulated activity with a potency that was one log less in BAT compared with heart. Propranolol fully blocked the high-affinity component but only weakly blocked the low-affinity component of CGP-12177A-stimulated activity in BAT. Pindolol was also less potent in BAT but inhibited the CGP-12177A-stimulated activity in a manner similar to the inhibition of the isoproterenol-stimulated activity, suggesting the CGP-12177A activation was beta-receptor mediated. Binding curves of [125I]iodocyanopindolol ([125I]ICYP) in competition with CGP-12177A demonstrated a shift to lower affinity in the presence of beta,gamma-imidoguanosine 5'-triphosphate, indicating that CGP-12177A has agonist properties with respect to the [125I]ICYP binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin E2 desensitizes cAMP-mediated pepsinogen secretion in chief cells

1991 ◽  
Vol 261 (5) ◽  
pp. G858-G865 ◽  
Author(s):  
S. Fiorucci ◽  
K. E. McArthur
Keyword(s):  
Adenylate Cyclase ◽  
Guinea Pig ◽  
Prostaglandin E2 ◽  
Vasoactive Intestinal Peptide ◽  
Adenylate Cyclase System ◽  
Chief Cells ◽  
Cyclic Monophosphate ◽  
Camp Generation ◽  
Pepsinogen Secretion ◽  
In Cells

To evaluate whether pretreatment with prostaglandin E2 (PGE2) could desensitize pepsinogen secretion in chief cells from guinea pig, chief cells were pretreated with 10 microM PGE2 for up to 30 min. Desensitization of subsequent PGE2-stimulated secretion was maximal after 15 min, averaging only 29 +/- 9% (SE) of pepsinogen secretion in control cells stimulated with 10 microM PGE2. Desensitization was half-maximal with 30 nM PGE2. PGE2 pretreatment at 4 degrees C did not cause desensitization. In cells pretreated with 10 microM PGE2 for 15 min and then given 60 min to recover, responsiveness increased to 79 +/- 7% of that for control cells stimulated with PGE2. Thus the desensitization was reversible. Pretreatment with PGD2 and PGF2a did not alter subsequent PGE2-mediated secretion. PGE2-induced desensitization was heterologous but mediator specific because pepsinogen secretion was reduced in response to adenosine 3',5'-cyclic monophosphate (cAMP)-mediated agents (secretin and vasoactive intestinal peptide) but not Ca(2+)-mediated agents (CCK-8, gastrin, or carbachol). Pretreating chief cells with 10 microM PGE2 did not significantly alter cAMP generation in response to PGE2, secretin, or 3-isobutyl-1-methylxanthine, suggesting that desensitization was not mediated by an alteration in the receptor-coupled adenylate cyclase system. Because PGE2 pretreatment also desensitized pepsinogen secretion induced by the synthetic cAMP analogues 8-BrcAMP and 2'-O-monobutyryl-8-BrcAMP, it is likely that the ability of PGE2 to desensitize pepsinogen secretion in chief cells isolated from guinea pig is due to a mechanism distal to generation of cAMP.

Effects of age, gender, and senescence on β-adrenergic responses of isolated F344 rat brown adipocytes in vitro

1998 ◽  
Vol 274 (4) ◽  
pp. E726-E736 ◽  
Author(s):  
Annette M. Gabaldón ◽  
Roger B. McDonald ◽  
Barbara A. Horwitz
Keyword(s):  
Uncoupling Protein ◽  
Physiological State ◽  
Gender Effects ◽  
Rapid Weight Loss ◽  
Brown Adipocytes ◽  
Cl 316,243 ◽  
Age Related ◽  
Brown Adipose ◽  
Camp Levels

We previously reported greater age-related attenuation of cold-induced thermoregulation and brown adipose tissue thermogenic capacity in male vs. female F344 rats. With onset of the rapid weight loss that occurs near the end of the lifespan, this age-related attenuation becomes severe. We refer to this “end-of-life” physiological state of older rats as senescence. Here, we measured oxygen consumption of isolated brown adipocytes and found no age (6 vs. 12 vs. 26 mo) or gender effects on maximal norepinephrine (NE)- or CL-316,243 (β3-adrenergic agonist)-induced responses. In contrast, brown adipocytes from 22- to 26-mo-old senescent rats (males and females) consumed 51–60% less oxygen during maximal stimulation with NE and CL-316,243 than did cells from 26-mo-old presenescent rats. This attenuation was associated with lower (65–72%) uncoupling protein 1 concentrations but no alterations in NE-induced cAMP levels or lipolysis. Our data indicate that senescence, but not chronological age, significantly impacts NE-/β3-mediated thermogenesis of isolated brown adipocytes and that this effect involves altered mitochondrial rather than altered membrane or cytosol events.

Second messenger signaling mechanisms of the brown adipocyte thermogenic program: an integrative perspective

2017 ◽  
Vol 0 (0) ◽  
Author(s):  
Fubiao Shi ◽  
Sheila Collins
Keyword(s):  
Adipose Tissue ◽  
Natriuretic Peptides ◽  
Second Messenger ◽  
Proton Channel ◽  
Brown Adipocyte ◽  
Brown Adipocytes ◽  
Fat Depots ◽  
Signaling Mechanisms ◽  
Brown Adipose ◽  
Non Coding Rnas

Abstractβ-adrenergic receptors (βARs) are well established for conveying the signal from catecholamines to adipocytes. Acting through the second messenger cyclic adenosine monophosphate (cAMP) they stimulate lipolysis and also increase the activity of brown adipocytes and the ‘browning’ of adipocytes within white fat depots (so-called ‘brite’ or ‘beige’ adipocytes). Brown adipose tissue mitochondria are enriched with uncoupling protein 1 (UCP1), which is a regulated proton channel that allows the dissipation of chemical energy in the form of heat. The discovery of functional brown adipocytes in humans and inducible brown-like (‘beige’ or ‘brite’) adipocytes in rodents have suggested that recruitment and activation of these thermogenic adipocytes could be a promising strategy to increase energy expenditure for obesity therapy. More recently, the cardiac natriuretic peptides and their second messenger cyclic guanosine monophosphate (cGMP) have gained attention as a parallel signaling pathway in adipocytes, with some unique features. In this review, we begin with some important historical work that touches upon the regulation of brown adipocyte development and physiology. We then provide a synopsis of some recent advances in the signaling cascades from β-adrenergic agonists and natriuretic peptides to drive thermogenic gene expression in the adipocytes and how these two pathways converge at a number of unexpected points. Finally, moving from the physiologic hormonal signaling, we discuss yet another level of control downstream of these signals: the growing appreciation of the emerging roles of non-coding RNAs as important regulators of brown adipocyte formation and function. In this review, we discuss new developments in our understanding of the signaling mechanisms and factors including new secreted proteins and novel non-coding RNAs that control the function as well as the plasticity of the brown/beige adipose tissue as it responds to the energy needs and environmental conditions of the organism.

Role of serotonergic input in the regulation of the beta-adrenergic receptor-coupled adenylate cyclase system

Science ◽  
1982 ◽  
Vol 218 (4575) ◽  
pp. 900-901 ◽  
Author(s):  
A Janowsky ◽  
F Okada ◽  
D. Manier ◽  
C. Applegate ◽  
F Sulser ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptor ◽  
Adenylate Cyclase System ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic

scholarly journals The .BETA.-adrenergic receptor/adenylate cyclase system in the cardiac ventricles of a hypertrophic cardiomyopathy rat model.

1992 ◽  
Vol 56 (4) ◽  
pp. 376-383 ◽  
Author(s):  
SHINICHI YAMAMOTO ◽  
HIROSHI KATSUME ◽  
MASAO NAKAGAWA ◽  
TOSHIRO KURIBAYASHI ◽  
TSUNEICHI HASHIMOTO ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Adenylate Cyclase ◽  
Rat Model ◽  
Adrenergic Receptor ◽  
Adenylate Cyclase System ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Cardiac Ventricles

EVIDENCE FOR A SEPARATE ADENYLATE CYCLASE SYSTEM RESPONSIVE TO BETA-ADRENERGIC STIMULATION IN THE RENAL CORTEX OF THE RAT

1974 ◽  
Vol 77 (3) ◽  
pp. 604-611 ◽  
Author(s):  
Norman H. Bell ◽  
John Fleming ◽  
Joanne Benedict ◽  
Lisa Pantzer
Keyword(s):  
Parathyroid Hormone ◽  
Adenylate Cyclase ◽  
Renal Cortex ◽  
Blocking Agent ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Increased Activity

ABSTRACT Previous studies in other laboratories had indicated that some of the effects of parathyroid hormone on skeletal tissue and the renal tubule to influence ion metabolism can be produced by beta-adrenergic stimulation. Studies were carried out to determine whether the same adenylate cyclase system in rat renal cortex is activated by parathyroid hormone and isoproterenol. At maximal effective concentration of dose response, parathyroid hormone (2 × −5 m) increased adenylate cyclase activity by some 415 per cent, isoproterenol (10−6 m) increased activity by some 40 to 50 per cent, vasopressin (10−5 m) increased activity by some 96 per cent and porcine calcitonin (10−5 m) increased activity by some 92 per cent. Dl-propranolol (10−5 m), a beta-adrenergic receptor blocking agent, prevented the increase in enzyme activity produced by isoproterenol (10−6 m), did not diminish the increase in activity produced by parathyroid hormone (10−6 m) and did not influence basal adenylate cyclase activity by itself. The combined maximal concentrations of isoproterenol together with either parathyroid hormone, vasopressin or porcine calcitonin were additive. These results indicate that there is an adenylate cyclase system in rat renal cortex which can be activated by beta-adrenergic stimulation with isoproterenol, and is separate from the systems responsive to parathyroid hormone, vasopressin or calcitonin.

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