Inhibition of fast axonal transport and microtubule polymerization in vitro by colchicine and colchiceine

The effects of colchicine and colchiceine on fast axonal transport in frog sciatic nerves were studied in vitro. Colchiceine inhibited the transport to about the same extent as colchicine. Preincubation at low temperature potentiated the inhibitory effect of either drug. The polymerization of purified brain tubulin was inhibited by colchiceine at 5-10 times higher concentrations than colchicine. The similarity of the effects obtained with colchicine and colchiceine indicates that both drugs arrest axonal transport by interfering with microtubule function. Colchicine and colchiceine did not affect the levels of high energy phosphates (ATP and CrP) in frog nerves indicating that a reduced energy supply was not responsible for the arrested transport.