Effects of diazepam on dorsal root potentials induced by cortical paroxysmal activity

Abstract

The effects of diazepam (DZ), 0.5–1 mg/kg, i.v., on inhibitory presynaptic mechanisms induced at the spinal level by the appearance of cortical seizures produced by pentetrazol have been studied in intact cats anaesthetized with pentobarbital. Spontaneous dorsal root potentials (DRP), induced by isolated discharges and by paroxysmal cortical seizures, were abolished by DZ. After the paroxysmal activity, heterosensory and heterosegmental DRP's, due to cortical hyperexcitability, were suppressed by DZ. In contrast, the segmental DRP which was reduced by pentetrazol, was increased by DZ. These data suggest that: (1) DZ exerts a direct action at the spinal level by increasing segmental presynaptic inhibition as previously described by others. (2) DZ decreases or suppresses presynaptic controls of supraspinal origin by its depressive action on supraspinal structures involved in these phenomena.