Effects of diazepam (cercine) on the somatosensory evoked responses following tooth pulp stimulation in rat.

Effect of diazepam on the somatosensory evoked responses (SER) following tooth pulp stimulation was investigated in Wistar albino rats. The SERs were recorded from the contralateral surface of the skull with a silver ball electrode and 200 responses were averaged with a medical computer. Generally, SERs were found to be composed of a sequence of four components named P1 (first positive wave), N1 (first negative wave), P2 (second positive wave), and N2 (second negative wave) in a 100 msec analysis time. Diazepam enhanced only the amplitude of the P1 component to about 500% of the control, while it suppressed other N1, P2, and N2 components to about 30, 40, and 20% of the control, respectively. The maximum suppressed effect appeared about 30 min after the diazepam injection and the effect was maintained for about 150 min. One possible explanation for the present result is that the activities of the synapses mostly in cortical layter IV evoked by tooth pulp stimulation may be enhanced but the activities of the cortical cells may be suppressed by diazepam injection.