NEURONE-SPECIFIC enolase immunoreactivity (NSE-IR) was examined in the
hippocampal dentate gyrus 5 h, 24 h and 6 days following local inject
ion of N-methyl-D-aspartate (NMDA), and was compared with Nissl substa
nce and acid fuchsin staining. Five and 24 hours post-injection extrac
ellular NSE-IR was increased, and the number of NSE-IR neurones in the
granule cell layer was decreased. However, at 24 h post-injection onl
y, 10-15% of the granule cells were strongly NSE-IR, in contrast to th
e Nissl/acid fuchsin staining which showed a homogeneous population of
degenerating neurones. By 6 days there were no viable neurones in the
lesion area stained by either method. These results show that neurona
l degeneration after an excitotoxic insult occurs in a non-uniform way
in an apparently homogeneous group of central neurones.