title: Possible role of nitric oxide in radiation-induced salivary gland dysfunction.
abstract: In this study, we developed a murine model of xerostomia to elucidate the mechanism of radiation-induced salivary gland dysfunction and determined the levels of nitric oxide (NO) in the salivary glands to assess its involvement in the salivary dysfunction induced by radiation. In addition, an inhibitor of NO synthesis was administered to the model in vivo, and its effect on saliva secretion was investigated. Salivary gland irradiation at a dose of 15 Gy caused a significant decrease in secretion compared to unirradiated salivary glands. There were no marked differences between the irradiated mice and unirradiated mice in water or food consumption or in body weight changes. The NO levels in the cultured salivary gland epithelial cells were increased by treatment with a combination of interferon gamma (Ifng), interleukin 1-beta (Il1b), and tumor necrosis factor alpha (Tnfa). Irradiation increased the NO level in the salivary gland tissue. The presence of N(G)-monomethyl-l-arginine acetate (l-NMMA), an inhibitor of NO synthesis, caused a decrease in the NO level in cultured salivary gland tissues after irradiation. Administration of l-NMMA to irradiated mice improved saliva secretion. These results suggest that excessive production of NO induced by radiation is involved in the formation of radiation-induced xerostomia. The finding that administration of an inhibitor of NO synthesis ameliorated the dysfunction of irradiated salivary glands indicates that NO plays a role as a mediator of the dry mouth symptoms that occur after irradiation.
authors.affiliation: Department of Oral Medicine, Tokyo Dental College, Chiba, Japan.
authors.forename: Ienaka
authors.initials: I
authors.lastname: Takeda
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kizu
authors.forename: Okamoto
authors.initials: O
authors.lastname: Yoshitaka
authors.forename: Ichiro
authors.initials: I
authors.lastname: Saito
authors.forename: Gen-Yuki
authors.initials: GY
authors.lastname: Yamane
mesh_terms: D000818:Animals; D002478:Cells, Cultured / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D023421:Models, Animal; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology; D052247:Nitric Oxide Synthase Type II; D011833:Radiation Injuries, Experimental / Q000378:metabolism*; D012469:Salivary Glands / Q000737:chemistry / Q000187:drug effects / Q000503:physiopathology / Q000528:radiation effects*; D012472:Salivation / Q000187:drug effects / Q000528:radiation effects*; D013047:Specific Pathogen-Free Organisms; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014987:Xerostomia / Q000209:etiology* / Q000378:metabolism; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D007371:Interferon-gamma; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse