ABSTRACT
Objective At present, modern medicine cannot yet clarifythe mechanism of radiation-induceddamage (RID) to salivary glands and its treatment and protective measures remain in the exploration stage .This study was to explore the mechanism of RIDto the submandibular gland and observe the effect of Dark Plum Spray ( DPS) on the submandibular gland after RID in order to provide some evidence for its further application . Methods Using the random number table , 84 healthy Wistar male rats were divid-ed into a normal, an RID model, and an experimental group ,all fed normally.The rats of the RID model groupwere left untreated , while those of the experimental group were intervened with DPS , tid, after RID.On the 1st, 7th, 14th, and 28th day after irradiation, 7 rats were taken from each group for measurement of the body weight, collection of the saliva , and calculation of the salivary flow rate.The submandibular glands were harvested for determination of the mRNA and protein expressions of autophagy-related Atg5 by RT-PCR and Western blot . Results In the 7th day after irradiation , the average body weight in NG[(239.87±16.50)g] was significantly higher (P<0.05) than UG[(213.84±14.42)g] and EG[(222.71±11.14)g].In the 14th ,28th day after irradiation, the average body weight in UG and EG were significantly lower ( P<0.05) than NG;the average body weight in EG was significantly higher ( P<0.05) than UG.In the 1st , 14th day after irradiation , the salivary flow rate in UG and EG were lower than NG but there were no significantly difference(P>0.05).In the 7th day after irradiation, the salivary flow rate in NG[(49.29±16.90)μL/min] and EG[(50.99±6.79)μL/min] were significantly higher (P<0.05) than UG[(30.13±13.19)μL/min].In the 28th day after irradiation, the salivary flow rate in NG[(69.29±11.32)μL/min] were significantly higher (P<0.05) than UG[(49.26±14.13)μL/min] and EG[(46.56±13.60)μL/min] .In the 1st , 7th and 14th day after irradiation , RT-PCR showed that the expressions of Atg 5 in UG and EG were significantly higher(P<0.05) than NG.In the 1st , 7th and 14th day after irradiation, Western blot showed that the expressions of Atg 5 in UG and EG is on the upper trend than NG;In the 1st , 7th day after irradiation , there were no significantly difference between UG and EG .In the 28th day after irradiation , Western blot showed that the expressions of Atg 5 in UG is on the declining trend than NG . Conclusion The autophagic activity of submandibular gland cells may associated with early radiation -induced injury , and Dark Plum Spray may en-hance the action of theanti-apoptosis cytokine in repairingradiation-induceddamageto the submandibular gland .
ABSTRACT
BACKGROUND: There is little information available in the mechanism of radiation-induced salivary gland injury, and its treatment and prevention are still at the exploratory stage.OBJECTIVE: To establish a rat model of radiation-induced xerostomia with 18 Gy electron beam and to observe the pathological changes of the submandibular gland and changes in saliva ingredients.METHODS: Totally 115 Wistar rats were randomly divided into exposure and control groups: the rats in the exposure group were subjected to anesthesia, and the submandibular gland received 18 Gy electron beam radiation to establish the model of radiation-induced xerostomia. The rats in the control group were only anesthetized but not exposed to radiation. The water intake was recorded at 21 dys after modeling. The saliva was collected and the submandibular gland was removed at 1, 3, 7, 14, 21, 28, 35 and 42 days to detect the saliva volume and submandibular gland index,and the morphological changes of the submandibular gland were observed by hematoxylin-eosin staining.RESULTS AND CONCLUSION: At 1-21 days after modeling, the average daily water intake was (6.42±1.91) mL in the exposure group and (4.82±1.20) mL in the control group, respectively (P < 0.05). During 42 days after modeling, the saliva secretion volume in the exposure group was lower than that in the control group, which was the lowest on day 7,and the difference was significant at 7, 21, 28 and 42 days after modeling between two groups (P < 0.05). The submandibular gland index in the exposure group was significantly lower than that in the control group at 1 and 21-42 days after modeling (P < 0.05). Hematoxylin-eosin staining results showed that in the exposure group, the rat submandibular gland appeared with inflammatory infiltration, glandular atrophy and karyopyknosis that were aggravated with time until day 42. To conclude, the rat model of radiation-induced xerostomia is established successfully with 18 Gy beam, characterized as increased water intake, decreased saliva volume and progressive aggravation of pathological injury of the submandibular gland.