Selective vulnerability of spinal motor neurons to reactive dicarbonyl compounds, intermediate products of glycation, in vitro: implication of inefficient glutathione system in spinal motor neurons.

We investigated the effects of two reactive dicarbonyl compounds, methylglyoxal (MG) and 3-deoxyglucosone (3-DG), on cultured spinal cord neurons. Incubation of cortical and spinal neurons with MG and 3-DG for 24 h induced neuronal death in a dose-dependent manner. Spinal motor neurons were more vulnerable than spinal non-motor neurons and cortical neurons. Treatments with glutathione (GSH)-augmenting agents showed protective effects against MG and 3-DG neurotoxicity. Motor neurons were better protected than non-motor neurons. Cotreatment, but not pretreatment, of aminoguanidine (AG), a known inhibitor of advanced glycation end-products (AGEs) from crosslinking, showed a protective effect on spinal neurons with no difference in protective rates between motor and non-motor spinal neurons. Treatments with GSH depleting agents enhanced the neurotoxicity of MG and 3-DG on spinal neurons. Motor neurons were more vulnerable than non-motor neurons with GSH-depleting treatments prior to MG and 3-DG exposures. These data demonstrate that spinal motor neurons are more vulnerable to dicarbonyl compounds, and this selectivity might be related to the relatively inefficient GSH system in spinal motor neurons.