Hu J W, Sharav Y, Sessle B J
Faculty of Dentistry, University of Toronto, Canada.
Brain Res. 1990 May 21;516(2):271-9. doi: 10.1016/0006-8993(90)90928-5.
We have recently demonstrated that deafferentation of the adult cat's maxillary or mandibular posterior tooth pulps results in statistically significant changes in mechanoreceptive field and response properties of low-threshold mechanoreceptive (LTM) brainstem neurons in trigeminal (V) subnucleus oralis. These effects were however reversible, and the statistically significant changes were apparent only for 1-2 weeks after the deafferentation procedure. The aim of this study was to examine the effects of a more extensive deafferentation involving both maxillary and mandibular pulps. In accordance with our earlier study, the pulps of the teeth were deafferented and, in a 'blind' design, the physiological properties of oralis LTM neurons were studied in each of these animals and compared with those from control, unoperated cats. Statistically significant changes in mechanoreceptive field and response properties were produced in these animals with both maxillary and mandibular quadrants deafferented and were similar to those documented in our earlier study involving deafferentation of only one quadrant. However, as well as occurring at 1-2 weeks after the deafferentation procedures, the changes were still apparent at 4 weeks following the deafferentation. In addition, we also documented that changes could be produced by a two-stage deafferentation procedure involving first the mandibular pulps and then, 3 weeks later, the maxillary pulps. These findings thus demonstrate that an extensive deafferentation procedure involving mandibular as well as maxillary tooth pulps can produce statistically significant changes in the physiological properties of V brainstem neurons of adult cats that may last at least 4 weeks postoperatively.
