Effects of colchicine on myelination of rabbit optic nerve: a biochemical study

The effects of intravitreous injections of colchicine on the myelination of the optic nerve were studied in rabbits at different times during development using biochemical and morphological techniques. Myelin basic protein concentrations and 2',3-cyclic nucleotide 3'-phosphodiesterase activities were affected in a similar way by colchicine treatment and reflected the degree of myelination of the tissue. During early development, colchicine produced axonal degeneration and secondary demyelination (Wallerian degeneration). Later, axonal and myelin abnormalities were more variable. Some demyelination was observed amd myelin formation also may have been inhibited. Thus, the effect of colchicine was proportional to the degree of optic nerve and retinal maturation (the youngest being the most sensitive) and, to a lesser extent, to the dosage, Under conditions used for this study, no remyelination was observed. In adult animals, no lesions could be detected histologically one to four months after injection of colchicine, Thus, intravitreous administration of colchicine is a useful chemical technique for producing Wallerian degeneration in optic nerves of young developing rabbits.