Effect of cervical sympathetic nerve stimulation on nociceptive jaw opening reflex in the cat.

In anaesthetized cats the electrical stimulation of the cervical sympathetic nerve induces a considerable increase (150-250%) in the nociceptive jaw opening reflex elicited by tooth pulp stimulation (JOR). The mechanisms potentially responsible for this effect are discussed and the possibility is suggested, that a portion of the response is due to a modulatory action exerted by the sympathetic on the nociceptive input.