Cholinergic activity modulates the survival of retinal ganglion cells in culture: the role of M1 muscarinic receptors

Abstract

The control of natural cell death is mediated by neurotrophins released by target, afferent and glial cells. In the present work we show that treatment of retinal cells ‘in vitro’ for 48 h with 25 μM carbamylcholine induced a two-fold increase in retinal ganglion cells survival. This effect was dose-dependent and mediated by M1 receptors since it could be blocked by 1 μM telenzepine (a M1 receptor antagonist) and mimicked by 200 μM oxotremorine (a M1 receptor agonist). The effect of carbamylcholine was abolished by 10 μM BAPTA-AM (an intracellular Ca2+ chelator), 30 μM dantrolene (an inhibitor of ryanodinic receptors), 500 nM H-89 (an inhibitor of PKA), 1.25 μM chelerythrine chloride (an inhibitor of PKC) and 50 μM PD-98059 (a MEK inhibitor). Treatment with 10 μM genistein (an inhibitor of tyrosine kinase), 25 μM LY-294002 (a PI-3 kinase blocker), 30 nM brefeldin-A (a blocker of polypeptides release), 50 nM K-252a (a Trk receptor inhibitor) and 20 μM fluorodeoxyuridine (an inhibitor of cell proliferation) totally inhibited the effect of carbamylcholine. Taken together our results indicate that muscarinic activity controls the survival of retinal ganglion cells through a mechanism involving the release of polypeptides and activation of Irk receptors.