Effects of Chorda-lingual Denervation on NOS Expression in the Rat Submandibular Gland

Nitric oxide (NO) gas has been recognized to diffuse readily across the membrane and bind directly to molecule (s) inside target cells. In the salivary gland, eNOS and nNOS are constitutively expressed. iNOS was also reported to express in neoplastic salivary tissues. Regarding the role of NO in the salivary gland, it has been suggested that it may control blood flow to the glands and furthermore involve in growth and development of the gland. The present study hypothesized that denervation of parasympathetic secretomotor fibers may lead to salivary secretion dysfunction, changing NOS expression. The gland weight on the denervated side significantly decreased from 3 days after the denervation, comparing the control (p＜0.01). Some atrophic and hyperchromatic changes, but no inflammatory reactions were found for the whole period of the experiment. All three kinds of NOS were mainly expressed in the ducts of the gland in both the control and experimental sides. Immunoreactivities of nNOS and eNOS were not noticeably different from those of the control. However, iNOS was also detected in ducts in the normal submandibular gland by immunohistochemical staining. The iNOS expression increased more than 2 times at denervated side of the gland than the control. These results suggest that NOS isoforms, especially iNOS following chorda-lingual denervation may lead to matrix loss or cell death in the salivary gland.