ABSTRACT
Single-nerve activities were recorded in the gasserian ganglia of anesthetized cats by glass extracellular micro-electrodes to determine whether sensory endings exist within the alveolar bone. Trigeminal cells responded to mechanical and/or thermal stimulation applied to the maxillary bone. Some were activated by specific kinds of fairly precise mechanical stimuli (moderate forces applied in a preferential direction); others exhibited a coarse mechanical sensitivity. In addition, electrical stimulation was applied to the maxillary bone to determine the conduction velocities of the relevant fibers. These mainly ranged between 1 and 6 m/s, which indicates that the fibers belonged to the small-diameter category (thinnest myelinated and unmyelinated fibers). Similar results were obtained from animals with osseointegrated implants. It was concluded that the alveolar bone is endowed with sensory endings capable of detecting mechanical and thermal changes, and that these receptors may provide compensatory sensitivity in edentulous subjects whose main (periodontal) sensitivity has been eliminated.
Subject(s)
Alveolar Process/innervation , Sensory Receptor Cells/physiology , Action Potentials/physiology , Anesthesia, General , Animals , Cats , Dental Implants , Electric Stimulation , Electrophysiology , Glass , Jaw, Edentulous/pathology , Maxilla/innervation , Microelectrodes , Nerve Fibers/physiology , Nerve Fibers, Myelinated/physiology , Neural Conduction , Osseointegration , Periodontium/innervation , Physical Stimulation , Stress, Mechanical , Temperature , Trigeminal Ganglion/physiology , Trigeminal Nerve/physiologyABSTRACT
Unitary activities were recorded in the ventromedial nucleus of the hypothalamus (VHM) of anesthetized rats. Cells responding to periodontal stimulation (100-200 g disto-mesial traction applied to an upper incisive) were selected. The effects of gastric stimulation (2-5 ml distension) were then investigated. Out of the 40 cells activated (22 cells) or inhibited (18 cells) by periodontal stimulation, only seventeen were influenced by gastric stimulation. Eight of them responded in the same way and nine in the opposite way. Unlike the periodontal stimulation, which elicited specific spatio-temporal patterns, the gastric stimulation had only weak effects. These data nevertheless demonstrate that periodontal-gastric convergences exist in the VHM nucleus, which is consistent with the role previously ascribed to this area in alimentary behaviour.
Subject(s)
Gingiva/innervation , Stomach/innervation , Ventromedial Hypothalamic Nucleus/physiology , Afferent Pathways/cytology , Afferent Pathways/physiology , Anesthesia , Animals , Electric Stimulation , Female , Gingiva/physiology , Male , Microelectrodes , Rats , Rats, Wistar , Stomach/physiology , Ventromedial Hypothalamic Nucleus/cytologyABSTRACT
In anesthetized rats, mechanical stimulations, the direction and intensity of which could be modified, were applied to the superior incisive while single neurone activities were recorded within the VHM region by means of extracellular glass microelectrodes. The great sensitivity of periodontal receptors to the direction and the intensity of the stimulations was demonstrated at this level. This finding, which is reported here in detail for the first time, suggests that the periodontal afferents might be involved in physiological mechanisms including food intake regulation and osteomorphogenesis.
