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This Article Full Text Full Text (PDF) All Versions of this Article: 99/5/2251    most recent 00794.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Saito, K. Articles by Iwata, K. PubMed PubMed Citation Articles by Saito, K. Articles by Iwata, K.

Modulation of Trigeminal Spinal Subnucleus Caudalis Neuronal Activity Following Regeneration of Transected Inferior Alveolar Nerve in Rats

¹Department of Physiology and ²Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry; ³Department of Physiology, School of Dentistry at Tokyo, Nippon Dental University; ⁴Division of Applied System Neuroscience, Advanced Medical Research Center, Nihon University Graduate School of Medical Science, Tokyo; ⁵Division of Oral and Maxillofacial Biology, Institute for Oral Science, Matsumoto Dental University, Nagano, Japan; and ⁶Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada

Submitted 14 July 2007; accepted in final form 3 March 2008

Modulation of trigeminal spinal subnucleus caudalis neuronal activity following regeneration of transected inferior alveolar nerve in rats. To clarify the neuronal mechanisms of abnormal pain in the face innervated by the regenerated inferior alveolar nerve (IAN), nocifensive behavior, trigeminal ganglion neuronal labeling following Fluorogold (FG) injection into the mental skin, and trigeminal spinal subnucleus caudalis (Vc) neuronal properties were examined in rats with IAN transection. The mechanical escape threshold was significantly higher at 3 days and lower at 14 days after IAN transection, whereas head withdrawal latency to heat was significantly longer at 3, 14, and 60 days after IAN transection. The number of FG-labeled ganglion neurons was significantly reduced at 3 days after IAN transection but increased at 14 and 60 days. The number of wide dynamic range (WDR) neurons with background (BG) activity was significantly higher at 14 and 60 days after IAN transection compared with naïve rats, and the number of WDR and low-threshold mechanoreceptive (LTM) neurons with irregularly bursting BG activity was increased at these two time points. Mechanically evoked responses were significantly larger in WDR and LTM neurons 14 days after IAN transection compared with naïve rats. Heat- and cold-evoked responses in WDR neurons were significantly lower at 14 days after transection compared with naïve rats. Mechanoreceptive fields were also significantly larger in WDR and LTM neurons at 14 and 60 days after IAN transection. These findings suggest that these alterations may be involved in the development of mechanical allodynia in the cutaneous region innervated by the regenerated IAN.