[Effect of cholinergic substances on nociceptive evoked responses in specific thalamic nuclei].

The effect of the M-cholinomimetic arecoline and M-cholinolytic metamizil, n-cholinomimetic lobelin and n-cholinolytic -506 (beta-ethylenespasmolytin) on the formation of nociceptive responses induced by dental pulp stimulation was studied by means of microinjections into the rabbit thalamus preparations VPM and VPL. Arecoline and -506 decreased while metamizil and lobelin increased the amplitude of the primary responses. No changes in the latent periods were noted. It is concluded that the activation of the M-cholinergic structures of specific nuclei of the thalamus reduces the nociceptive responses. The activation of the N-cholinergic structures potentiates the nociceptive responses in specific relays.