ONO-1603, a potential antidementia drug, delays age-induced apoptosis and suppresses overexpression of glyceraldehyde-3-phosphate dehydrogenase in cultured central nervous system neurons

Primary cultures of rat cerebral cortical cells and cerebellar granule cell s die by an apoptotic mechanism after more than 2 weeks in cultures in the absence of medium change and glucose supplement, a process termed age-induc ed apoptosis of cultured neurons. Our preliminary study has shown that age- induced apoptosis of cerebellar granule cells is protected by pretreatment with tetrahydroaminoacridine (THA), an antidementia drug. In this study, we systematically compared the neuroprotective effects of THA with those of ( S)-1-[N-(4-chlorobenzyl)succinamoyl]pyrrolidine-2-carbaldehyde (ONO-1603), a novel prolyl endopeptidase inhibitor and potential antidementia drug. Bot h ONO-1603 and MA effectively delay age-induced apoptosis of cerebral and c erebellar neurons, as demonstrated morphologically with toluidine blue and fluorescein diacetate/propidium iodide staining or biochemically by DNA lad dering analysis on agarose gels. ONO-1603 is about 300 times more potent th an THA, with a maximal protective effect at 0.03 and 10 mu M, respectively. ONO-1603 shows a wide protective range of 0.03 to 1 mu M in contrast to a narrow effective range of 3 to 10 mu M for THA. Moreover, ONO-1603 is nonto xic to neurons, even at the high concentration of 100 mu M, whereas MA elic its severe neurotoxicity at a dose of greater than or equal to 30 mu M. Bot h ONO-1603 and THA robustly suppress overexpression of glyceraldehyde-3-pho sphate dehydrogenase (GAPDH; EC 1.2.1.12) mRNA and accumulation of GAPDH pr otein in a particulate fraction of cultured neurons undergoing age-induced apoptosis. Because we documented that GAPDH overexpression participates in neuronal apoptosis induced by various insults, we conclude that the neuropr otective actions of ONO-1603 and THA appear to be mediated by suppression o f this protein overexpression.