Metabotropic glutamate receptor agonists protect from oxygen-glucose deprivation- and colchicine-induced apoptosis in primary cultures of cerebellar granule cells

The effects of the metabotropic glutamate receptor agonists against apoptos is induced by oxygen-glucose deprivation or colchicine were studied in the primary cultures of mature cerebellar granule cells. Oxygen-glucose depriva tion (90 min) or addition of colchicine (1 mu M) resulted in neuronal damag e as revealed by Trypan Blue assay 12 h later. Further analysis demonstrate d that the cells exposed to oxygen-glucose deprivation or colchicine exhibi t typical features of apoptosis: internucleosomal DNA fragmentation, conden sation and fragmentation of chromatin and typical DNA ladder on agarose gel electrophoresis. Metabotropic glutamate receptor agonist, (1S,3R)-1-aminoc ycloheptane-trans-1,3-dicarboxylic acid, acting at group I and II receptors , and selective agonist, (2S,1 'R,2R',3R')-2(2,3dicarboxycyclopropyl)glycin e, acting at group II receptors, added to cells recovering from oxygen-gluc ose deprivation exerted neuroprotective action against oxygen-glucose depri vation-induced apoptosis. Similar neuroprotective effects of metabotropic g lutamate receptor agonists were observed against colchicine-induced apoptos is. The results thereby provide evidence that metabotropic glutamate recept or agonists have therapeutic potential in the treatment of pathologies asso ciated with increased neuronal apoptosis. The selective protein kinase C in hibitor bisindolylmaleimide (100 nM) abolished the neuroprotective action o f (1S,3R)-1-aminocycloheptane-trans-1,3-dicarboxylic acid, whereas the acti vator of adenylyl cyclase forskolin (10 mu M) abolished the neuroprotective action of (2S,1 'R,2R',3R')-2(2,3-dicarboxycyclopropyl)glycine (30 mu M) a gainst colchicine-induced apoptosis. It is concluded that both phosphoinositide hydrolysis with consequent activ ation of protein kinase C and inhibition of adenylyl cyclase seem to contri bute to the neuroprotective action of metabotropic glutamate receptor agoni sts against neuronal apoptosis in the primary culture of cerebellar granule cells. (C) 1999 IBRO. Published by Elsevier Science Ltd.