Effect of colchicine on the fine structure of the neuromuscular junction.

Repeated injections of colchicine into the forearms of normal adult newts led to the disappearance of microtubules within some nerves and a concomitant loss of specialized morphological features at the neuromuscular junction. Within 2 weeks, the postsynaptic folds decreased in height and number, became flattened and eventually disappeared. In addition, nerve terminals in drug-treated animals became separated from the muscle surface and were highly congested with masses of synaptic vesicles. The present findings show that colchicine has an effect on the structural integrity of the neuromuscular junction. These effects could be direct; secondary to retraction of the nerve from the muscle surface; or the result of interference with the proper transport and/or release of neurotrophic substances. [ABSTRACT FROM AUTHOR]