Stimulation of dental pulp with simultaneous recording of the jaw opening reflex in the rat.

The processing of nociceptive information in the central nervous system has been analysed in most studies by activation of peripheral nerves. However, the limitation of this method is the simultaneous activation of noxious and inocuous fibers. Nevertheless, the stimulation of the tooth pulp is believed to activate mainly nociceptive fibers which could be the method of choice. On the other hand, the response to nociceptive activation of the dental pulp is easily quantified by the amplitude of the jaw opening reflex, a nocifensive flexion withdrawal reflex. In this protocol we describe a technique to manufacture and implant electrodes in lower incisors of the rat and a method to prepare and insert stainless steel twisted bipolar electrodes to record the electromyographic activity of both digastric muscles, in response to nociceptive dental pulp stimulation. This approach was applied in the study of the analgesic effects of the rat's striatal stimulation.