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Islet‐Activating Protein Inhibits the β‐Adrenergic Receptor Facilitation Elicited by γ‐Aminobutyric Acid B Receptors
Author(s) -
Wojcik Walter J.,
Ulivi Massimo,
Paez Ximena,
Costa E.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb11769.x
Subject(s) - gabab receptor , receptor , pertussis toxin , g protein , agonist , long term potentiation , chemistry , medicine , endocrinology , biology , biochemistry
γ‐Aminobutyric acid B (GABA B ) receptor recognition sites that inhibit cyclic AMP formation, open potassium channels, and close calcium channels are coupled to these effector systems by guanine nucleotide binding proteins (G proteins). These G proteins are ADP‐ribosylated by islet‐activating protein (IAP), also known as pertussis tokin. This process prevents receptor coupling to these G proteins. In slices of cerebral cortex and hippocampus from rat, stimulation of GABA B receptors with baclofen, a receptor agonist, also potentiates the accumulation of cyclic AMP stimulated by β‐adrenergic agonists. It was unknown whether those GA‐BA B receptors that potentiate the β‐adrenergic response were also sensitive to IAP. IAP was injected intracerebroventric‐ularly into rats to ADP‐ribosylate IAP‐sensitive G proteins. Four days after the IAP injection, 38% and 52% of these G proteins from cerebral cortex and hippocampus, respectively, were ADP‐ribosylated by the IAP injection. In slices of both structures prepared from IAP‐treated rats, the GABA B receptor‐mediated potentiation of the β‐adrenergic receptor response was attenuated. Thus, many GABA B receptor‐mediated responses are coupled to IAP‐sensitive G proteins.