[Effects of tooth pulp stimulation on single unit activity of the amygdala in cats]

Responses induced by tooth pulp stimulation were studied in 27 gallamine immobilized adult cats. Single units were recorded from the amygdala using stainless steel microelectrodes. Of 57 amygdaloid neurons, 8 were responsive to only non-nociceptive (tap and/or hair bending) stimuli, 7 were responsive to both nociceptive (pinch) and non-nociceptive stimuli, 18 were responsive to nociceptive stimuli, non-nociceptive stimuli and tooth pulp stimulation, and the others did not respond to these stimuli. The neurons in the amygdala responsive to tooth pulp stimulation were localized in the nucleus amygdaloideus centralis (pars lateralis) [Acl], nucleus amygdaloideus centralis (pars medialis) [Acl] and nucleus amygdaloideus basalis (pars magnocellularis) [Abm]. The response induced by tooth pulp stimulation was depressed by morphine and reversed by naloxone. These results suggest that Acl, Acm and Abm in the amygdala may receive pain sensation evoked by tooth pulp stimulation. Moreover, there is a possibility that these nuclei may be related to the emotional component involved in nociceptive processing.