N-OMEGA-NITRO-L-ARGININE METHYL-ESTER PREVENTS APOPTOSIS INDUCED IN THE LATERAL GENICULATE-NUCLEUS BY LIGHT DEPRIVATION IN ADULT-RABBIT

EXPOSURE of adult rabbits to darkness for 48 h produces bilateral DNA fragmentation in the lateral geniculate nucleus as revealed in brain s ections by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-b iotin nick end labelling (TUNEL) technique, suggesting an apoptotic ty pe of cell death. In agreement with the latter deduction, light micros copy assessment of the morphological characteristics showed marginaliz ation and condensation of nuclear chromatin, typical features of apopt osis. These effects were abolished by systemic administration of N-ome ga-nitro-L-arginine methyl ester, an inhibitor of nitric oxide (NO) sy nthesis, whereas the D isomer was ineffective. In conclusion, the pres ent data demonstrate that light deprivation for 48 h produces apoptosi s in the lateral geniculate nucleus of rabbit and suggest that NO migh t be involved.