Changes in peripheral innervation and nociception in reticular type and erosive type of oral lichen planus.

Background: Oral lichen planus (OLP) is a chronic inflammatory lesion in oral mucosa. Reticular (OLP-R) and erosive (OLP-E) types of OLP are the common forms that have been found in dental clinics. The aim of this investigation is to determine the correlation between neurogenic inflammation and nociception associated with OLP-R and OLP-E. Materials and Methods: The oral mucosal lesions from six patients with OLP-E, four with OLP-R and three with noninflamed oral mucosa, which represent normal mucosa, were identified by morphometric analysis of nerve fibers containing immunoreactive protein gene product (PGP) 9.5. The level of inflammation was measured with hematoxylin and eosin staining and the level of nociception was analyzed with visual analog scale measurement. Results: We found that 1) an increase in peripheral innervation was related to the size of the area of inflammatory cell infiltration from both OLP-R and OLP-E; 2) the pattern of PGP 9.5-immunoreactivity among OLP-R and OLP-E was not significantly different (P=0.23); and 3) the correlation between nociception and an increase in PGP 9.5-immunoreactivity was not found in OLP-E and in OLP-R. Conclusions: Our findings suggest that an increase in peripheral innervation may lead to increased inflammation, which is part of the immunopathogenesis of OLP. Differences in nociception between OLP-R and OLP-E arise from the pathogenesis of each lesion, not from the differences in peripheral innervation.

Rat colon epithelium response to hypoxia is modified by intrinsic innervation blockade

Background/Aim: Short-circuit current (Isc) and transepithelial potential difference (PD) of rat distal colon decrease during acute hypoxia and overshoot on reoxygenation. It is not known whether tonic intrinsic nervous activity may influence these responses. Methods: Preparations lacking the submucosal plexus (isolet mucosa) and preparations retaining it (mucosa-submucosa) were mounted in Ussing chambers at 37 degrees Celsius and gassed with 95 percent O2 -5 percent CO2; Isc and PD were monitored. A 5-min hypoxia with 95 percent N2-5 percent CO2 was followed by reoxygenation. The procedure was repeated in the presence of the nervous blocking agent, tetrodotoxin (10(-6)M) in the serosal side of the chamber. Results: In the isolated mucosa (n=10) hypoxia reduced Isc by -55 + 5 percent and PD by -54 + 6 percent below baseline; reoxygenatory overschoots were, respectively, + 60 + 17 percent and + 16 percent. Tetrodotoxin slightly and transiently reduced baseline Isc (-16 + 2 percent) and PD (-14 + 3 percent), with a small resistivity increase. It did not significatively modify the responses to responses to either hypoxia or reoxygenation. In mucosa-submucosa preparations (n=9) hypoxia reduced Isc (-54 + 8 percent) and PD (-61 + 4 percent). On reoxygenation Isc and PD were increased, respectively, +30 + 5 percent and +19 + 6 percent over baseline. Tetrodotoxin reduced baseline Isc (-59,6 + 5 percent) and PD (61,3 + 6 percent). It enhanced hypoxic Isc and PD decreases (-80 + 5 percent), but not the reoxygenatory overschoots. Conclusions: 1) Tetrodotoxin affects baseline Isc and PD more intensely in submucosal plexus innervated preparations than in the isolated mucosa. 2) The epithelial electrical response to acute hypoxia appears to be modulated by tonic neural activity.