The effect of foot-shock on the noxious-evoked activity of neurons in the rostral ventral medulla

Abstract

The effect of foot-shock on the noxious-evoked activity of rostral ventral medulla (RVM) neurons was investigated in anesthetized rats. Neurons were first classified as on-cells if they fired faster during noxious pinch or as off-cells if they fired slower. Exposure to a 20 Hz squarewave at 2.5 or 3.5 mA administered for two minutes decreased the noxious-evoked responses of both cell types: on-cells showed a reduced increase in firing, while off-cells showed a reduced decrease in firing. The results indicate that stress-induced analgesia is accompanied by alterations in the activity of on- and off-cells. © 1990.