Alpha-Adrenergic Receptor Activity, Cyclic Amp and Lipolysis in Adipose Tissue of Hypothyroid Man and Rat

Reckless, John; Gilbert, Christine; Galton, D. J.

doi:10.1677/joe.0.0680419

Cited by 29 publications

(12 citation statements)

References 21 publications

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“…Likewise, the sensitivity of the alpha-receptor appears to be normal in adult diabetics. Our techniques are sufficiently sensitive to demonstrate changes in catecholamine receptor sensitivity, and in hypothyroidism we have confirmed the results of Rosenqvist et al [2] on release of glycerol, demonstrating an increased alpha-receptor sensitivity in adipocytes, which can be reversed by treatment of patients with l-thyroxine [4]. It is therefore unlikely that changes in catecholamine receptor sensitivity are responsible for the increased flux of plasma fatty acids that is frequently observed in adult diabetes.…”

Section: Discussionsupporting

confidence: 86%

“…In hypothyroidism there is increased activity of the alpha-receptor of adipocytes so that stimulation with catecholamines (noradrenaline or adrenaline) results in an impaired increment of glycerol compared either to euthyroid controls [2] or to hypothyroid tissue stimulated by a predominant beta-agonist such as isoprenaline [3]. The receptor defect in hypothyroidism is reversible with thyroxine therapy [4] and may contribute to the low levels of plasma fatty acids observed in hypothyroidism.…”

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confidence: 99%

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Catecholamine receptor sensitivity and the regulation of lipolysis in adult diabetes

Reckless

Galton

1976

Diabetologia

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Summary. The sensitivity of alpha-and beta-adrenergic receptors, and the antilipolytic actions of prostaglandin E 1 or insulin on adipose tissue of obese diabetic and non-diabetic subjects have been studied. Accumulation of cyclic AMP in adipose tissue and release of glycerol in response to several catecholamines (adrenaline, noradrenaline and isoprenaline) in the presence or absence of an alpha-adrenergic blocker (phentolamine) have been used to assess catecholamine receptor sensitivity. No differences in betareceptor activity were observed between diabetics and non-diabetics, either on glycerol release or accumulation of cyclic AMP; alpha-receptor activity was also similar, except for significantly less accumulation of cyclic AMP in diabetic tissue incubated with noradrenaline and phentolamine (p <0.01). The antilipolytic action of prostaglandin E 1 (at concentrations of 30 fM to 30 pM) on lipolysis (stimulated submaximally with isoprenaline, 10 -7 M) was similar in diabetic and control groups. The antilipolytic action of insulin (from 10 -I~ to 10 -6 M) on lipolysis was also similar between the groups. It is concluded that neither disorders of the catecholamine receptor nor of the antilipolytic actions of prostaglandin E 1 or insulin are responsible for the abnormalities of fatty acid metabolism in adult diabetes.

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Section: Discussionsupporting

confidence: 86%

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confidence: 99%

Catecholamine receptor sensitivity and the regulation of lipolysis in adult diabetes

Reckless

Galton

1976

Diabetologia

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“…Many studies in cells from different tissues have indicated that thyroid hormones are inactive in this regard (28)(29)(30)(31)(32)(33). On the other hand, T3 in vitro has been found to increase the cAMP concentration in spermatozoa from Macaca mulatta (34), and thyroxine to act similarly in rat osteogenic sarcoma cells in culture (17).…”

Section: Effects Of Alprenololmentioning

confidence: 99%

Studies of the mechanism by which 3,5,3'- triiodothyronine stimulates 2-deoxyglucose uptake in rat thymocytes in vitro. Role of calcium and adenosine 3':5'-monophosphate.

Segal¹,

Ingbar²

1981

J. Clin. Invest.

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A B S T R A C T The present experiments were designed to explore the mechanism whereby 3,5,3'-triiodothyronine (T3) stimulates the uptake of 2-deoxy-D-glucose (2-DG) in rat thymocytes in vitro. Addition of T3 evoked a transient, dose-related increase in cellular cyclic (c) AMP concentrations, evident within 5 min, followed soon by an increase in 2-DG uptake. The effects of T3 on both cAMP concentration and 2-DG uptake were dependent upon the presence of extracellular calcium. Epinephrine also induced a sequential increase in thymocyte cAMP concentration and 2-DG uptake. These responses were more prompt than those to T3, but were calcium independent. As with their combined effects on 2-DG uptake, T3 and epinephrine produced synergistic or additive effects on cellular cAMP concentration. Dibutyryl cAMP also stimulated 2-DG uptake, an effect that was more prompt than that of epinephrine, and, like that of epinephrine, was calcium independent.Prior or simultaneous addition of L-alprenolol (10 AM), which, we have previously shown, blocks the effect of both T3 and epinephrine on 2-DG uptake, also blocked the increase in thymocyte cAMP concentration induced by these agents. In contrast, Lalprenolol failed to block the increase in 2-DG uptake produced by dibutyryl cAMP. On the basis of these observations we suggest that T3 increases 2-DG uptake in the rat thymocyte by increasing the cellular concentration of cAMP, which then acts to enhance sugar transport. The increase in 2-DG uptake induced by epinephrine is also mediated by an increase in cAMP concentration. The greater

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“…Catecholamines seeril to be physiologically important mediators for lipid 'mijbilization in these cells (6)(7)(8)(9)(10)(11)(12)(13). Beta adrenergic stimulation increases adenylate cyclase activity, raises cyclic AMP, and enhances the cyclic AMP-dependent processes such as lipolysis, whereas alpha adrenergic activation, in general, has opposite effects (6)(7)(8)(9)(10)(11)(12)(13). These observations support the hypothesis put forward by Robison et al (14) that some cell types have both alpha and beta adrenoceptors that mediate opposite effects on cyclic AMP and cell function.…”

Section: Introductionmentioning

confidence: 99%

Pharmacological Characterizations of Adrenergic Receptors in Human Adipocytes

Burns¹,

Langley²,

Terry³

et al. 1981

J. Clin. Invest.

104

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A B S T R A CBeta and alpha-2 adrenergic receptors appeared to be positively and negatively coupled to adenylate cyclase, respectively. Cells or cell membranes were incubated with epinephrine (10 ,M) alone and in combination with the antagonists yohimbine (alpha-2) and prazosin (alpha-i). Epinephrine alone prompted a modest increase in adenylate cyclase activity, cyclic AMP, and glycerol release, an index of lipolysis. Yohimbine (0.1 ,tM) greatly enhanced these actions whereas prazosin was without effect. The beta agonist, isoproterenol, stimulated glycerol release, whereas the alpha-2 agonist, clonidine, inhibited lipolysis and cyclic AMP accumulation.

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Alpha-Adrenergic Receptor Activity, Cyclic Amp and Lipolysis in Adipose Tissue of Hypothyroid Man and Rat

Cited by 29 publications

References 21 publications

Catecholamine receptor sensitivity and the regulation of lipolysis in adult diabetes

Catecholamine receptor sensitivity and the regulation of lipolysis in adult diabetes

Studies of the mechanism by which 3,5,3'- triiodothyronine stimulates 2-deoxyglucose uptake in rat thymocytes in vitro. Role of calcium and adenosine 3':5'-monophosphate.

Pharmacological Characterizations of Adrenergic Receptors in Human Adipocytes

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