Action of calycanthine on nervous transmission in cockroach central nervous system.

Calycanthine, the principal alkaloid of the order Calycanthaceae, has been isolated from a species of the genus Psychotria (Rubiaceae) occurring in some Pacific islands. The drug is considered as a very powerful convulsant poison but very little is known about its mechanism of action. The symptoms observed were similar to those of some neuropoisons such as strychnine. The properties of this alkaloid have been investigated on the genesis, conduction, and transmission of the nerve impulse, using giant axons of the cockroach (Periplaneta americana). Calycanthine hydrochloride (10(-5) M), which did not alter nervous conduction in pre- and post-synaptic fibers, significantly reduced the efficacy of the synaptic transmission.