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Adenosine stimulates cAMP‐mediated taurine release from LRM55 glial cells
Author(s) -
Madelian V.,
Silliman S.,
Shain W.
Publication year - 1988
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490200205
Subject(s) - adenosine , adenosine receptor , ibmx , taurine , adenosine a1 receptor , adenosine a3 receptor , endocrinology , chemistry , medicine , adenosine receptor antagonist , receptor , biology , biochemistry , agonist , forskolin , amino acid
The possible role of adenosine as a modulator or transmitter in the central nervous system was tested by measuring its effects on LRM55 astroglial cells. Two related cellular responses were measured–receptor activated increases in intracellular cAMP and cAMP‐mediated taurine release. Taurine is a neuroinhibitory amino acid that is taken up, stored, and released from primary cultures of astrocytes and astroglial cells. Three‐minute incubations of cells with adenosine caused a dosedependent accumulation of intracellular cAMP and release of the taurine (EC 50 = 5.0 × 10 −5 M and 1.6 × 10 −6 M, respectively). That the cellular responses were mediated through the activation of specific adenosine receptors was indicated by the observations that the adenosine receptor antagonist isobutylmethylxanthine (IBMX) but not the beta‐adrenergic receptor antagonist 1‐propranolol inhibited responses to adenosine. The study of various adenosine analogs showed a rank order of potency (chloroadenosine = 5′‐(N‐ethyl)carboxamidoadenosine > N 6 ‐(L‐2‐phenylisopropyl)‐adenosine > cyclohexyladenosine = cyclopentyladenosine) characteristic of the low affinity A 2 ‐type adenosine receptors that have been associated with cAMP elevation in several tissues. These results indicate that, in addition to directly affecting neurons, adenosine may have a primary site of action on astroglial cells resulting in taurine release and subsequent inhibition of neuronal activity.