Comparison between the effect of colchicine and lumicolchicine on axonal transport in rat motor neurons.

The mitotic inhibitor colchicine (COL) and its isomer lumi-colchicine (lumi-COL) were tested on the axonal transport of acetylcholine (ACh), cholineacetyltransferase (CAT) and ACh-esterase (AChE) in rat motor nerves in vivo. COL was found to be far more effective in blocking axonal transport of all 3 substances than was an equimolar concentration (0.1 M) of lumi-COL, when injected into the sciatic nerve. Since COL and lumi-COL have similar properties as regards binding to cellular membranes, but differ markedly in their binding capacity to microtubule protein, the results give strong support for the theory that microtubules are essential for intra-axonal transport in mammalian nerves.