EFFECTS OF NEREISTOXIN AND ITS DERIVATIVES ON THE SPINAL CORD AND MOTOR NERVE TERMINALS

Abstract

Nereistoxin is a potent neuroactive substance isolated first by Nitta (1) from the Japanese species of annelid, Lumbriconereis heteropoda Marenz. In our preliminary pharmacological study of synthetic nereistoxin (2), it has been shown in the cat with chronically implanted electrodes that the intraperitoneal injection of 5 mg/kg produced the muscle relaxing signs due to the moderate impairment of the neuromuscular transmission. At the higher dose level than 10 mg/kg, however, this toxin caused salivation, mydriasis, panting, tremor and tonic convulsion which accompanied the spike and dome pattern in electroencephalogram (EEG). Components of this convulsion, tremor and twitching of the limb and body trunk muscles in addition to the EEG seizure patterns were also caused by this toxin in unanesthetized encephale isole cats. This indicates that the sites of the convulsive action of this toxin exist in both the supraspinal and spinal levels.
The present study was carried out in an attempt to clarify the mechanisms in the spinal cord and at the motor nerve terminal for producing convulsion by nereistoxin. Comparative study of this toxin with the derivatives in the potency was also done.