In vivo regulation of acetylcholine release via adenosine A(1) receptor in rat cerebral cortex

The roles of the endogenous adenosine on acetylcholine release via adenosine A(1) receptor were investigated in rat cerebral cortex using brain microdialysis. Oral administration of KF15372 (8-dicyclopropylmethyl-1,3-dipropylxanthine), a novel selective adenosine A(1) receptor antagonist, at doses of 1.25, 5, and 20 mg/kg, significantly increased the extracellular levels of acetylcholine in rat cerebral cortex. Selective A(1) agonist N-6-((R)-phenylisopropyl) adenosine (R-PIA) did not affect the extracellular level of acetylcholine by both oral (1.25 mg/kg) and intracortical administrations (0.3 mu M) via dialysis probe. These results suggest that the extracellular level of acetylcholine is under tonic inhibitory control of endogenous adenosine via the A(1) receptor.