APOPTOSIS INDUCED BY BETA-N-OXALYLAMINO-L-ALANINE ON A MOTONEURON HYBRID CELL-LINE

It has been suggested that beta-N-oxalylamino-L-alanine, a non-protein amino acid present in the Lathyrus Sativus seeds, may play a role in the etiopathogenesis of neurolathyrism, a toxic form of motor neuron d isease clinically characterized by a severe spastic paraparesis. In or der to investigate the mechanisms of beta-N-oxalyiamino-L-alanine-medi ated cell death, we studied the effect of this neurotoxin as well as o ther excitatory amino acids agonists on the growth and survival of mot oneuron hybrid ventral spinal cord 4.1 cells. beta-N-oxalylamino-L-ala nine was toxic to ventral spinal cord 4.1 cells in a concentration-dep endent fashion (0.5-10 mM). Among the excitatory amino acids tested, o nly glutamate (1-10 mM), quisqualate (1 mM) and, with less extent, bet a-N-methylamino-L-alanine (10 mM) induced a significant reduction of c ell survival. The effect of Lathyrus Sativus neurotoxin was a slow pro cess, becoming apparent only after 24-48 h of incubation. Interestingl y, a mathematical analysis applied to the time course and dose curve o f beta-N-oxalylamino-L-alanine toxicity suggested that even for very l ow concentrations of the amino acid it is theoretically possible to pr edict a time-dependent effect. The cell death was not blocked by antag onists of N-methyl-D-aspartate or non-N-methyl-D-aspartate receptors; aurintricarboxylic acid and alpha-tocopherol gave a partial protection ; cysteine (1 mM) prevented the toxic effect of both Lathyrus Sativus neurotoxin and glutamate as well as quisqualate. Morphologically, in t he presence of either beta-N-oxalylamino-L-alanine, glutamate or quisq ualate, ventral spinal cord 4.1 cells showed apoptotic features also c onfirmed by ISEL technique and agarose gel electrophoresis of genomic DNA. Thus, our results suggest that in ventral spinal cord 4.1 motoneu ron hybrid cells, in the absence of functional synaptic excitatory ami no acid receptors. beta-N-oxalylamino-L-alanine induces cell degenerat ion through an apoptotic mechanism, possibly mediated by a block of cy stine/glutamate X(c)(-) antiporter.