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Adenosine receptor‐mediated modulation of acetylcholine release from rat striatal synaptosomes
Author(s) -
Kirkpatrick Karen A.,
Richardson Peter J.
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb13905.x
Subject(s) - cgs 21680 , veratridine , agonist , adenosine , chemistry , endocrinology , acetylcholine , medicine , adenosine a2a receptor , synaptosome , adenosine receptor , pharmacology , adenosine a1 receptor , receptor , biology , biochemistry , central nervous system , sodium , sodium channel , organic chemistry
1 The effects of A 1 and A 2a adenosine receptor agonists on the veratridine‐evoked release of [ 3 H]‐acetylcholine ([ 3 H]‐ACh) from rat striatal synaptosomes was investigated by use of the A 1 ‐selective agonist, R ‐PIA and the 185 fold selective A 2a agonist, CGS 21680. The effects of NECA, which is equipotent at both receptor subtypes, were also studied. 2 The evoked release of [ 3 H]‐ACh was significantly enhanced by the A 2a agonist CGS 21680 but decreased by the A 1 agonist, R ‐PIA. The effects of NECA were dependent on the concentration used, with high concentrations inhibiting and low concentrations enhancing the evoked release of [ 3 H]‐ACh. In the absence of any antagonists, the rank order of potency for these three drugs on increasing [ 3 H]‐ACh release was CGS 21680 > NECA > R ‐PIA. 3 The stimulatory effects of CGS 21680 and low NECA concentrations on evoked [ 3 H]‐ACh release were antagonized by the A 2a receptor antagonists, CP66,713 (300 n m ) and CGS 15943A (50 n m ) whilst the inhibitory effects of R ‐PIA were reversed by the selective A 1 antagonist, DPCPX (4 n m ). In the presence of DPCPX, NECA greatly enhanced the evoked release of [ 3 H]‐ACh at all concentrations studied when, during such A 1 receptor blockade, the rank order of potency was NECA ≫ CGS 21680 > R ‐PIA. 4 These results demonstrate that both A 1 and A 2a adenosine receptors modulate the veratridine‐evoked release of [ 3 H]‐ACh from rat striatal synaptosomes.