IMMUNOHISTOCHEMICAL ASSESSMENT OF AXONAL AND TERMINAL DEGENERATION - MORPHOLOGICAL-CHANGES IN THE DEAFFERENTED RAT VISUAL-SYSTEM HAVE RELEVANCE TO HUMAN-DISEASE

Immunohistochemical labelling with antibodies against the triplet of n eurofilaments (NFs) and synaptophysin (SYN) was tested as marker for n euronal degeneration in rat visual system. Degeneration of retinal axo ns and synapses in the subcortical visual system was studied 1, 2, 4, 8 and 21 days after unilateral transection of the optic nerve. Walleri an degeneration of retinal fibres in the brachium colliculi and subcor tical visual nuclei correlated with a decreased immunostaining for NFs . Immunostaining for non-phosphorylated epitopes on NFs of the low and middle weight classes revealed an accumulation of NFs in degenerating retinal terminals of the dorsal lateral geniculate nucleus and superi or colliculus, e.g. neurofilamentous hypertrophy. Antibodies directed against different epitopes on NFs of the high molecular weight class f ailed to label neurofilamentous hypertrophy in degenerating retinal te rminals. A monoclonal antibody directed against the synaptic vesicle p rotein, SYN was applied as marker for synaptic degeneration. In contro ls, the SYN antibody showed a ubiquitous distribution with a strong im munoreactivity in retinal terminal fields. No changes of immunostainin g for SYN were identified in deafferented visual structures. The obser vations made in the well-defined experimental paradigm of fibre degene ration can serve as basis for studying more complex pathological event s like in focal cerebral ischaemia or trauma.