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Pertussis toxin treatment prevents 5‐HT 5a receptor‐mediated inhibition of cyclic AMP accumulation in rat C6 glioma cells
Author(s) -
Thomas Elizabeth A.,
Matli Jennifer R.,
Hu John L.,
Carson Monica J.,
Sutcliffe J. Gregor
Publication year - 2000
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 - 10.1002/1097-4547(20000701)61:1<75::aid-jnr9>3.0.co;2-9
Subject(s) - pertussis toxin , ketanserin , 5 ht receptor , receptor , forskolin , adenylate kinase , g protein , adenylate cyclase toxin , gs alpha subunit , cyclase , biology , receptor antagonist , stimulation , medicine , endocrinology , microbiology and biotechnology , biochemistry , antagonist , serotonin
We have investigated the functional coupling of the rat 5HT 5a receptor subtype to adenylate cyclase in a rat C6 glioma cell line. In 5HT 5a receptor‐transfected cells, 5HT caused a concentration‐dependent inhibition of forskolin‐stimulated cAMP accumulation, with an EC 50 value of 41 nM and a maximal effect of 57% inhibition. This effect was dependent on the concentration of forskolin used to elevate cAMP levels. Methiothepin (1 μM), which has high affinity for the 5HT 5a receptor, antagonized the 5HT 5a receptor‐mediated inhibition, and unmasked a stimulation of cAMP formation similar to that observed in untransfected cells, whereas ketanserin (0.1 μM) enhanced the inhibitory effect of 5HT. Pertussis toxin treatment (0.5 μg/ml) completely blocked the inhibitory effect of 5HT on cAMP formation, also revealing increase in cAMP accumulation. Pretreatment of the transfected membranes with pertussis toxin abolished subsequent ADP‐ribosylation of a 41 kDa protein, correlating the cAMP effect with a functional uncoupling of an inhibitory G protein from its receptor. These results demonstrate an efficient functional coupling of the rat 5HT 5a receptor to the inhibition of adenylate cyclase via a pertussis toxin‐sensitive G αi , inhibitory G‐protein. J. Neurosci. Res. 61:75–81, 2000. © 2000 Wiley‐Liss, Inc.