[Effect of stimulation of the tooth pulp on gastrointestinal motility in rabbits]

Effects of electrical stimulation of the inciser tooth pulp on the gastrointestinal motility were investigated in the rabbit anesthetized with urethane and chloralose. Pulpal Stimulation caused an excitatory or an inhibitory effect in the gastric body and antrum and the ducodenum. After bilateral splanchnicotomy the excitatory response to the pulpal stimulation was reinforced or the inhibitory response converted to the excitatory response. An additional cervical vagotomy abolished the excitatory and inhibitory response. Atropine diminished the spontaneous efferent discharges of vagal gastric branch (VGB) and abolished the excitatory and inhibitory response to stimulation of the pulp and the inferior alveolar nerve. This agent also blocked the potentials of the VGB evoked by afferent stimulation of the inferior aveolar nerve. Hexamethonium bromide abolished the excitatory and inhibitory responses to the pulpal stimulation but did not affect spontaneous discharges and increased discharges of the VGB to pulpal stimulation. Morphine produced decreased rate of the spontaneous discharge of the VGB and abolished increased rate of discharges of the VGB as well as the gastrointestinal responses to pulpal stimulation. It is concluded from these results that the afferent impulses caused by pulpal stimulation and the inferior alveolar nerve 'reflex'ly activate the vagal motor nuclei in the medulla oblongata and the sympathetic splanchnic nuclei in the thoracic segments through the trigeminal nerve: The vagus nerves produced the excitatory response in the gastrointestinal motility, while the splanchnic nerves caused the inhibitory response. It was supposed that sites of action of atropine and morphine is not in peripheral site, but in the central nerves site.