Adenosine and ADP prevent apoptosis in cultured rat cerebellar granule cells

Cerebellar granule cells (CGCs) explanted in vitro undergo death via apoptosis when the concentration of potassium is shifted from 25 mM to 5 mM. We report that adenosine and ADP, which act as neurotransmitters and neuromodulators in the brain, exert in cultured cerebellar granule cells a specific and marked antiapoptotic action with half-maximal effect in the 10-100 microM range. The action of adenosine is partly inhibited by the A1AR antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and is mimicked by the A1AR agonist 2-chloro-N6-cyclopentyladenosine (CCPA), while ADP effect, that is completely blocked by the P2x, P2y receptors noncompetitive antagonist suramine, is restored in the presence of the selective P2x purinoceptors agonist beta, gamma-methylene-L-ATP. These findings demonstrate that adenosine and ADP markedly inhibit the program of cell death in cerebellar granule cells and suggest that such an action is mediated via interaction with, respectively, A1 and P2x receptors.