The Effect of Prostaglandin E1on Norepinephrine-Induced Membrane Depolarization and Cyclic AMP Accumulation in Brown Fat Cells

Pharmacology ◽  
1973 ◽  
Vol 10 (3) ◽  
pp. 129-135 ◽  
Author(s):  
Jay Moskowitz ◽  
Gopal Krishna
Keyword(s):  
Cyclic Amp ◽  
Membrane Depolarization ◽  
Brown Fat ◽  
Prostaglandin E ◽  
Fat Cells ◽  
Induced Membrane ◽  
Cyclic Amp Accumulation

Effect of NAD, nicotinamide and nicotinic acid on cyclic AMP accumulation by fat cells

1979 ◽  
Vol 306 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Francisco J. Moreno ◽  
Raymond E. Shepherd ◽  
John N. Fain
Keyword(s):  
Cyclic Amp ◽  
Nicotinic Acid ◽  
Fat Cells ◽  
Cyclic Amp Accumulation

scholarly journals Attenuated adenosine-sensitivity and decreased adenosine-receptor number in adipocyte plasma membranes in human obesity

1991 ◽  
Vol 279 (1) ◽  
pp. 17-22 ◽  
Author(s):  
J M Kaartinen ◽  
S P Hreniuk ◽  
L F Martin ◽  
S Ranta ◽  
K F LaNoue ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adenosine Receptors ◽  
Plasma Membranes ◽  
Normal Weight ◽  
Fat Cells ◽  
Cyclic Amp Accumulation ◽  
Obese Subjects ◽  
Receptor Number

Fat-cells were isolated from patients of body-mass indices (BMIs) ranging from 17.9 to 83.9 kg/m2. Isoprenaline-stimulated cyclic AMP accumulation in cells prepared from obese subjects as compared with normal-weight subjects, was less sensitive to inhibition by the adenosine agonist N6-(phenylisopropyl)adenosine (PIA) (P = 0.047). The inhibition of 7 beta-desacetyl-7 beta-[gamma-(N-methylpiperazino) butyryl]-forskolin-stimulated adenylate cyclase by PIA in the presence of adenosine deaminase was also much attenuated in crude plasma membranes of adipocytes prepared from massively obese patients as compared with lean controls (P = 0.0143). This difference was probably not due to different cell size, because adenylate cyclase of crude plasma membranes of large adipocytes was actually more sensitive to PIA than was adenylate cyclase of membranes of smaller fat-cells co-isolated from the same individual. The stimulatory effect of PIA on glucose uptake in the presence of adenosine deaminase was depressed in adipocytes prepared from obese subjects and correlated with BMI at r = -0.626 (P = 0.007) at 100 nM-PIA. The adenosine receptors were studied by using the adenosine antagonist 1,3-[3H]dipropyl-8-cyclopentylxanthine. The binding was rapid and proportional to protein concentration. There was no difference in the affinities of receptors in membranes of obese and normal-weight subjects; Kd values of all patients averaged 3.3 nM. Bmax values were 54 and 130 fmol/mg of protein in membranes prepared from seven obese and five control patients respectively. The Bmax values calculated per mg of protein correlated with BMI at r = -0.539 (P = 0.047). The adenosine content of adipose tissue was higher in obese than in control subjects. These results demonstrate an attenuated response of cyclic AMP accumulation, adenylate cyclase and glucose uptake to adenosine in fat-cells prepared from obese subjects, and suggest that this change is at least partly due to changes in the amount of adenosine receptors, but not their affinity. The decreased receptor number could be due to higher adenosine content. A higher adenosine concentration in adipose tissue could explain why lipolysis is inhibited in situ in obesity, and the desensitization could explain the diminished response to adenosine analogues in isolated fat-cells.

scholarly journals Rat fat-cells have three types of adenosine receptors (Ra, Ri and P). Differential effects of pertussis toxin

1985 ◽  
Vol 232 (2) ◽  
pp. 439-443 ◽  
Author(s):  
J A García-Sáinz ◽  
M L Torner
Keyword(s):  
Cyclic Amp ◽  
Adenosine Deaminase ◽  
Pertussis Toxin ◽  
Adenosine Receptors ◽  
Fat Cells ◽  
Differential Effects ◽  
Cyclic Amp Accumulation ◽  
Selective Agonists ◽  
Rat Fat Cells ◽  
In Cells

Activation of rat adipocyte R1 adenosine receptors by phenylisopropyladenosine (PIA) decreased cyclic AMP and lipolysis; this effect was blocked in cells from pertussis-toxin-treated rats. In contrast, the ability of 2′,5′-dideoxyadenosine to decrease cyclic AMP was not affected by pertussis-toxin treatment. Addition of adenosine deaminase to the medium in which adipocytes from control animals were incubated resulted in activation of lipolysis. Interestingly, adipocytes from toxin-treated rats (which had an already increased basal lipolysis) responded in an opposite fashion to the addition of adenosine deaminase, i.e. the enzyme decreased lipolysis, which suggested that adenosine might be increasing lipolysis in these cells. Studies with the selective agonists N-ethylcarboxamidoadenosine (NECA) and PIA indicated that adenosine increases lipolysis and cyclic AMP accumulation in these cells and that these actions are mediated through Ra adenosine receptors. Adenosine-mediated accumulation of cyclic AMP was also observed in cells preincubated with pertussis toxin (2 micrograms/ml) for 3 h. In these studies NECA was also more effective than PIA. Our results indicate that there are three types of adenosine receptors in fat-cells, whose actions are affected differently by pertussis toxin, i.e. Ri-mediated actions are abolished, Ra-mediated actions are revealed and P-mediated actions are not affected.

scholarly journals Adrenergic control of induction of type II iodothyronine 5′-deiodinase activity in cultured mouse brown adipocytes

1993 ◽  
Vol 292 (1) ◽  
pp. 303-308 ◽  
Author(s):  
S Pavelka ◽  
J Hermanská ◽  
M Baudysová ◽  
J Houstĕk
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Brown Fat ◽  
Fat Cells ◽  
Type Ii ◽  
Brown Adipocytes ◽  
Adrenergic Agents ◽  
Adrenergic Control ◽  
Stimulation Of

Iodothyronine 5′-deiodinase (5′D) of mouse brown adipocytes differentiated in cell culture was characterized in detail with respect to the adrenergic control of its biosynthesis. The stimulation of 5′D required mRNA and protein synthesis and was dependent on the stage of differentiation of the cells. The maximum induction was observed around confluence (7-day-old cells), in pre- and post-confluent cells the 5′D activity was significantly less induced. The transient responsiveness of brown fat-cells to the stimulatory effect of adrenergic agents was reflected also in the time course of the induction of 5′D by different concentrations of agonists. The maximum response occurred regularly after an 8 h incubation and implicated a rather fast turnover of the induced enzyme. On the basis of the inhibitory effects of cycloheximide and actinomycin D, the half-life of the induced 5′D and its mRNA were estimated to be 1.5 and 3.3 h respectively. The noradrenaline-induced 5′D activity was shown to be that of the type II enzyme, insensitive to propylthiouracil (PTU). The estimated values of its apparent Km for thyroxine, Km for the co-substrate dithiothreitol, and Vmax. in the presence of 1 mM PTU were 2 nM, 2.6 mM, and 0.1 pmol of I-/h per mg of protein respectively. The 5′D activity was effectively induced by forskolin and dibutyryl cyclic AMP, as well as by isoprenaline, noradrenaline and CGP-12177, but not by phenylephrine, cirazoline or oxymetazoline. This indicates that, contrary to previous observations in vivo, stimulation of 5′D in cultured brown fat-cells involves elevated cyclic AMP levels and is mediated predominantly via beta-receptors, particularly via the so-called beta 3-adrenoceptors.

EFFECTS OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE ON OVARIAN CYCLIC AMP AND PROSTAGLANDIN E IN VIVO IN RATS TREATED WITH INDOMETHACIN

1976 ◽  
Vol 70 (2) ◽  
pp. 285-291 ◽  
Author(s):  
G. L. RIGLER ◽  
G. T. PEAKE ◽  
A. RATNER
Keyword(s):  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Intravenous Injection ◽  
Follicle Stimulating Hormone ◽  
Prior Treatment ◽  
Prostaglandin E ◽  
Cyclic Amp Accumulation ◽  
Stimulating Hormone

SUMMARY The role of prostaglandins in both FSH- and LH-mediated increases in ovarian cyclic AMP was examined in rats in vivo. Dose-related increases in ovarian cyclic AMP levels were observed 10 min after intravenous injection of FSH or LH. No changes in ovarian prostaglandin E (PGE) content were detected after injection of either gonadotrophin at doses which substantially enhanced cyclic AMP accumulation. Prior treatment of rats with indomethacin produced a greater than 50% decrease in ovarian PGE levels, but did not prevent the FSH- or LH-induced rise in ovarian cyclic AMP concentration. These in vivo experiments do not support the concept that PGE plays a role as an obligatory mediator for the gonadotrophin-induced rise in ovarian cyclic AMP levels.

Effect of multiplication-stimulating activity (MSA) on the cyclic AMP level and proteoglycan synthesis in cultured chondrocytes

1983 ◽  
Vol 104 (1) ◽  
pp. 117-122 ◽  
Author(s):  
Mitsuko Tsuji ◽  
Yukio Kato ◽  
Yoshio Nomura ◽  
Masahiko Kinoshita ◽  
Yuichi Kumahara ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Human Fibroblasts ◽  
Inhibitory Effect ◽  
Proteoglycan Synthesis ◽  
Prostaglandin E ◽  
Dibutyryl Cyclic Amp ◽  
Cyclic Amp Accumulation ◽  
Rat Liver Cells ◽  
Sulphated Glycosaminoglycans ◽  
Cultured Chondrocytes

Abstract. Multiplication-stimulating activity (MSA), a somatomedin purified from conditioned medium of Buffalo rat liver cells, had little effect on the intracellular level of cyclic AMP when it markedly enhanced the synthesis of sulphated glycosaminoglycans in rabbit chondrocytes in culture. In addition, MSA did not inhibit prostaglandin E1- or parathyroid hormone-induced accumulation of cyclic AMP in the chondrocytes. On the contrary, MSA slightly decreased stimulation of cyclic AMP accumulation by prostaglandin in human fibroblasts. Dibutyryl cyclic AMP and MSA increased the incorporation of [35S]sulphate and [3H]serine into proteoglycans synthesized by rabbit chondrocytes, and their effects were additive. These findings suggest that somatomedin and dibutyryl cyclic AMP enhance sulphate proteoglycan synthesis through different mechanisms. The lack of inhibitory effect of MSA on cyclic AMP accumulation may be favourable for producing additive effects with cyclic AMP on proteoglycan synthesis and DNA synthesis in chondrocytes.

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