The role of morphological and functional changes in adrenergic nerves for the development of colchicine-induced supersensitivity in the rat vas deferens.

Local application of colchicine to the hypogastric plexus produced degenerative changes in about 40% of adrenergic nerve endings and a decrease in the neuromuscular transmission in the rat vas deferens. Unlike after denervation, both decreases in the number of normal nerve terminals and neuromuscular transmission induced by colchicine were incomplete and reversible. Although the time course of these changes was apparently related to that of the development of supersensitivity after colchicine treatment, the degeneration of adrenergic nerves does not seem to be an essential factor for the manifestation of colchicine-induced supersensitivity which is quantitatively and qualitatively identical to that induced by denervation. It is suggested that some neurotrophic factor(s) may contribute to the control of responsiveness of the smooth muscle and that the denervation-like supersensitivity is induced by colchicine through an interference of axonal transport in adrenergic nerves.