The Effect Of Capsaicin On The Morphology And The Expression Of NAMPT In ¹³¹I-damaged Parotid Gland

Objectives: The quality of life for patients can be decreased due to irreversible oral complaints,which caused by radiation damage in salivary gland after 131 iodine(¹³¹I)therapy to thyroid cancer.Nicotinamide phosphoribosyltransferase（NAMPT）is called long-lived protein,is recently reported that it could strengthen cell’s resistance to oxidative stress.Capsaicin is a vanilla amides alkaloid,which can promote glands srcretion.However,whether it does work in in ¹³¹I-damaged parotid gland has not been reported.To investigate the effect of capsaicin on the alteration of morphology and the expression of NAMPT in ¹³¹I-damaged parotid gland of rat.Methods: The total 36 Wistar rats were randomly divided into four groups: the control group,the capsaicin only group,the ¹³¹I treated only group,and the capsaicin treatment with ¹³¹I administration group.¹³¹I（0.5 mCi/100 g）was intraperitoneally injected to rats.Capsaicin cream was spread over the skin covering the parotid gland twice a day for 7 days.Parotid glands were removed under anesthetized by intraperitoneal injection of 0.4 ml/100 g chloral hydrate on day 7.Cell morphology of parotid gland was observed with hematoxylin/eosin-stain.Immunohistochemical assay was applied to detect the expression of NAMPT and Proliferating Cell Nuclear Antigen（PCNA）.Results: Capsaicin could alleviate weight loss caused by iodine radiation damage in parotid gland.The morphological changes of marked cell shrinkage,pyknotic nuclei and vacuolization were observed in acinar cells under light microscope after ¹³¹I treatment,whereas cell atrophy dramatically alleviated with capsaicin treatment.The expression of NAMPT in the ¹³¹I treated only group was decreased than that of the control group,while it was increased with capsaicin treatment.The capsaicin treatment with ¹³¹I administration group could promote the expression of PCNA in irradiated parotid gland.Results from Western Blot demonstrated that the protein expression of NAMPT was down-regulated by 34.19%（P < 0.05）in the simple irradiated group compared with the control group,and was up-regulated by 24.95%（P < 0.05）in the capsaicin treatment with ¹³¹I administration group compared with the ¹³¹I treated only group.Conclusions: These data indicated that capsaicin could reduce the ¹³¹I–induced cell injury in rat parotid gland.The underlying mechanism might be related to the upregulation of NAMPT,suggesting a new strategy for the prevention and treatment of radiation sialadenitis induced by ¹³¹I.