A temporal study of axonal degeneration and glial scar formation following a standardized crush injury of the optic nerve in the adult rat.

In this methodological study, we describe a standardized optic nerve injury model in adult rats. The temporal pattern of the glial response is mapped in relation to axonal regeneration and degeneration.A standardized optic nerve crush injury was made in adult rats, using a fine pair of forceps with a preset pressure of 0.6 N during 10 seconds.This crush injury resulted in a pronounced astroglial and microglial proliferation 2-7 dpi. Degenerative axons distal to the lesion presented a gradual decrease in neurofilament immunoreactivity. In contrast, Fluoro-Jade staining was gradually increased in these degenerative axons from 2-7 dpi. Regeneration was observed proximal to the lesion in sprouts double labeled with the tracer Fluoro-Gold and anti-GAP43.The standardized optic nerve crush injury model used in the present study resulted in a reproducible degenerative pattern including a pronounced astroglial and microglial proliferation. The gradual decrease in Neurofilament immunoreactivity in degenerative axons, and a gradual increase in Fluoro-Jade staining was paralleled with a spontaneous regeneration proximal to the lesion, shown with tracing and GAP43-immunoreactivity. The combination of these markers and this experimental setup thus allows analysis of the entire degenerative/regenerative process in a standardized CNS axotomy model.