Cyclic amp in freshly prepared thymocyte suspensions. evidence for stimulation by endogenous adenosine

Fredholm, Bertil B.; Sandberg, Göran; Ernström, Ulf

doi:10.1016/0006-2952(78)90041-2

Cited by 30 publications

(13 citation statements)

References 28 publications

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“…PhiPrAdo is an adenosine receptor agonist that is not readily transported into cells (13). Consistent with earlier reports of the lymphocyte A2 receptor (7,14), cAMP stimulation by PhiPrAdo was blocked by xanthines (data not shown). Under standard conditions of assay, unstimulated (basal) and PhiPrAdo-stimulated levels of cAMP in normal human lymphocyte preparations (n = 31) were 8.97 ± 0.88 (SEM) and 14.85 ± 1.37 pmol per 106 cells, respectively.…”

Section: Resultssupporting

confidence: 91%

“…This adaptive response appears to compensate for the acute activating effect of ethanol and may represent a form of cellular tolerance. Adenosine also interacts with receptors on human lymphocytes to stimulate the accumulation of cAMP (7,14,21), raising the possibility that this system might be affected by chronic ethanol abuse in humans. Indeed, lymphocytes from chronic alcoholics had about a 75% reduction in basal and adenosine receptor-stimulated levels of cAMP when compared to lymphocytes from normal individuals or patients with nonalcoholic liver disease.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Basal and adenosine receptor-stimulated levels of cAMP are reduced in lymphocytes from alcoholic patients.

Diamond¹,

Wrubel²,

Estrin³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

140

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Alcoholism causes serious neurologic disease that may be due, in part, to the ability of ethanol to interact with neural cell membranes and change neuronal function. Adenosine receptors are membrane-bound proteins that appear to mediate some of the effects of ethanol in the brain. Human lymphocytes also have adenosine receptors, and their activation causes increases in cAMP levels. To test the hypothesis that basal and adenosine receptor-stimulated cAMP levels in lymphocytes might be abnormal in alcoholism, we studied lymphocytes from 10 alcoholic subjects, 10 age-and sexmatched normal individuals, and 10 patients with nonalcoholic liver disease. Basal and adenosine receptor-stimulated cAMP levels were reduced 75% in lymphocytes from alcoholic subjects. Also, there was a 76% reduction in ethanol stimulation of cAMP accumulation in lymphocytes from alcoholics. Similar results were demonstrable in isolated T cells. Unlike other laboratory tests examined, these measurements appeared to distinguish alcoholics from normal subjects and from patients with nonalcoholic liver disease. Reduced basal and adenosine receptor-stimulated levels of cAMP in lymphocytes from alcoholics may reflect a change in cell membranes due either to chronic alcohol abuse or to a genetic predisposition unique to alcoholic subjects.Despite the widespread incidence of alcoholism, the molecular events accounting for intoxication, tolerance, and physical dependence after alcohol abuse are poorly understood. Ethanol is believed to intercalate into cell membranes, producing acute and adaptive changes in membrane fluidity (1, 2) or membrane constituents (3,4). Adenosine receptors are membrane-bound proteins that appear to mediate some of the effects of ethanol in the central nervous system (5). We recently reported (6) that ethanol acutely increases adenosine receptor-stimulated cAMP levels in a clonal neural cell line (neuroblastoma-glioma hybrid and that with time these cells adapt to the presence of ethanol, showing a reduction in adenosine receptor-stimulated cAMP levels. After chronic exposure to ethanol, the NG108-15 cells require ethanol to achieve normal levels of adenosine receptorstimulated cAMP, which may indicate a form of cellular "dependence." This process is completely reversible upon ethanol withdrawal.These observations suggest that intact single cells adapt to the presence of ethanol. Moreover, depressed adenosine receptor-stimulated cAMP levels in cells might be a biochemical change of pathophysiologic significance in chronic alcoholism. Since human lymphocytes have the same A2 adenosine receptors as the neuroblastoma cells (7), we could test directly whether alcoholics have altered cAMP levels. We undertook a controlled study of basal and adenosine receptor-stimulated cAMP levels in lymphocytes of chronic alcoholics, normal subjects, and patients with nonalcoholic liver disease. Mixed lymphocytes and T cells from chronic alcoholics showed a striking reduction in basal and adenosine receptor-stimulated cAMP levels. Moreov...

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Basal and adenosine receptor-stimulated levels of cAMP are reduced in lymphocytes from alcoholic patients.

Diamond¹,

Wrubel²,

Estrin³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

140

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“…Lymphocytes release adenosine (22,23), and we find that endogenously released adenosine appears to regulate the response of the adenosine receptor system in cultured lymphocytes (Fig. 1).…”

Section: Discussionmentioning

confidence: 71%

“…Experiments with lymphocytes from alcoholic subjects were conducted simultaneously with lymphocytes from nonalcoholic subjects (laboratory staff and members of a local Mormon church group). Both populations were the same age; alcoholic subjects ranging from 31 to 59 years of age and nonalcoholic subjects from 23 (22,23), extracellular accumulation of adenosine could desensitize and/or down-regulate the adenosine receptor during culture (24,25). This might account for the reduction in adenosine receptor-dependent cAMP levels we observed in cultured lymphocytes relative to freshly isolated lymphocytes.…”

Section: Methodsmentioning

confidence: 99%

Cultured lymphocytes from alcoholic subjects have altered cAMP signal transduction.

Nagy

Diamond

Gordon

1988

Proc. Natl. Acad. Sci. U.S.A.

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Previous work has shown that freshly isolated lymphocytes from alcoholic subjects show significantly reduced basal and adenosine receptor-stimulated cAMP levels. This decrease could be due to ethanol-induced cellular adaptation or to a genetic difference in the regulation of cAMP signal transduction. Therefore, we cultured human lymphocytes in defined medium without ethanol for 7-8 days and then examined differences in receptor-dependent cAMP accumulation between lymphocytes from alcoholic and nonalcoholic subjects. After four to six generations in culture without ethanol, lymphocytes from alcoholic subjects have significantly higher cAMP levels than do cells from nonalcoholic subjects. Thus, a difference in cAMP signal transduction is demonstrable in cells from alcoholic subjects grown without ethanol. We also found that cultured lymphocytes from both alcoholic and nonalcoholic subjects show a decrease in receptor-stimulated cAMP levels after exposure to 200 mM ethanol for 48 hr. To determine whether alcoholic subjects have increased sensitivity to ethanol, lymphocytes were exposed to only 100 mM ethanol for 24 hr. Under these conditions, receptor-dependent cAMP levels did not change in cells from nonalcoholic subjects. However, lymphocytes from alcoholic subjects showed a 39% decrease (P < 0.003) in adenosine receptor-stimulated cAMP levels. Taken together, the results show that (i) chronic ethanol treatment in culture reproduces the suppression of cAMP levels found in circulating lymphocytes from alcoholic subjects and (i) despite four to six cell divisions in culture without ethanol, lymphocytes from alcoholic subjects exhibit signiicantly increased adenosine receptor-dependent cAMP levels and increased sensitivity to chronic exposure to ethanol. These rmdings suggest that the suppression of cAMP levels observed in freshly isolated lymphocytes from alcoholic subjects results from both a direct effect of chronic exposure to ethanol and a genetic difference leading to altered cAMP signal transduction.Receptor-stimulated cAMP production is altered after acute and chronic exposure to ethanol (1-12). Although ethanol acutely stimulates receptor-dependent cAMP production, chronic exposure of cultured NG108-15 neural cells to ethanol decreases adenosine receptor-stimulated cAMP levels when measured in the absence of ethanol (8, 9). Similar findings have also been described for f3-adrenergic receptor stimulation of cAMP production in S49 mouse lymphoma cells (6) and prostaglandin E1 receptor stimulation in both NIE cells (7) and NG108-15 neural cells (9).We have suggested that decreased receptor-stimulated cAMP levels have pathophysiologic significance in chronic alcoholism (13). Freshly isolated lymphocytes from alcoholic subjects show a 75% reduction in basal and adenosine receptor-stimulated cAMP levels when compared with ageand sex-matched control subjects and patients with nonalcoholic liver disease (13). The results of that study indicated that reduced cAMP levels in lymphocytes could be used to distin...

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“…After 10 min, the supernatant medium was removed, 100 p\ 0.4M per chloric acid added to the cells, and cyclic AM P determined [11].…”

Section: Preparation O F Different Tissue Extractsmentioning

confidence: 99%

Search for Thymocyte Growth-Stimulating Activity in Extracts of Different Tissues and among Established Growth Factors and Thymic Maturation Hormones

Söder¹,

Ernström²

1983

Int Arch Allergy Immunol

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A thymocyte specific growth factor has previously been prepared from calf thymus. Similar activity is now shown to be present in thymus and spleen of guinea pigs, but not in lymph nodes, liver and kidney. Purified thymic maturation hormones, interleukins and several growth factors for other cell types than lymphocytes were tested and found not to stimulate DNA synthesis of thymocytes. A slight activity was found in thymosin fraction 5, known to contain at least 35 polypeptides. Our factor lacked comitogenic effect when tested in combination with concanavalin A (ConA) and phytohemagglutinin, did not promote continuous growth of ConA-induced lymphoblasts and did not affect the cyclic AMP level of thymocytes. The data indicate that our factor is functionally distinct from the purified hormones and defined factors tested.

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Cyclic amp in freshly prepared thymocyte suspensions. evidence for stimulation by endogenous adenosine

Cited by 30 publications

References 28 publications

Basal and adenosine receptor-stimulated levels of cAMP are reduced in lymphocytes from alcoholic patients.

Basal and adenosine receptor-stimulated levels of cAMP are reduced in lymphocytes from alcoholic patients.

Cultured lymphocytes from alcoholic subjects have altered cAMP signal transduction.

Search for Thymocyte Growth-Stimulating Activity in Extracts of Different Tissues and among Established Growth Factors and Thymic Maturation Hormones

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