Reactive glial protein synthesis and early disappearance of saxitoxin binding in degenerating rat optic nerve

The biochemistry of gliotic CNS tissue was assessed by monotoring changes in de novo protein synthesis distal to site of crush in the rat optic nerve between 3 and 20 days post-operatively. Radioactivity profiles on 12% polyacrylamide SDS gels showed reproducible peaks associated with protein(s) with dissociated molecular weights of 57K, 51K, 42K, 40K, 37K and 23K. Differences between crush and control nerves were observed with respect to the latter two peaks. De novo synthesis of 23K protein (comigrant with myelin proteolipid protein) was evident in control but not crushed nerves. Synthesis of 37K protein (identity unknown) was evident at 7, 10 and (to a lesser extent) 20 days post-operatively in crushed nerves, but not in crushed nerves at 3 days post-operatively or in unoperated nerves at any time point. The appearance of the synthesis of the 37K protein coincides with a drop in the level of functional axolemma (assessed by [3H]saxitoxin binding) in crushed nerves from 78% to 36% of control levels between 3 and 7 days post-operatively.