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Objectives: Salivary gland injury is one of the most common complications of radiotherapy in head‐and‐neck cancers. This study investigated the mechanism by which rapamycin prevents irradiation (IR)‐induced injury in the parotid glands. Materials and Methods: Miniature pigs either received (a) no treatment (NT), (b) IR in the right parotid gland for 5 consecutive days (IR), or intraperitoneal administration of rapamycin (Rap) 1 h prior to IR (IR + Rap). Tissues were collected at three distinct time points (24 h, 4 weeks, and 16 weeks) after IR. Histological analyses, western blot, and real‐time reverse transcriptase‐polymerase chain reaction were performed to explore the mechanisms of IR‐induced injury in the parotid gland. Results: Rapamycin treatment maintained parotid salivary flow 16 weeks post‐IR, preserved the number of acinar cells, and reduced parotid tissue fibrosis, as well as reduced apoptosis levels, decreased cleaved caspase‐3 expression, and increased the Bcl‐2/Bax ratio in the parotid glands. Autophagy marker LC3B was upregulated by rapamycin after IR, while P62 expression was downregulated. Rapamycin reduced the expression of pro‐inflammatory factors and the mesenchymal tissue fibrosis following IR. Conclusions: Rapamycin maintains gland homeostasis after IR by decreasing apoptosis, reducing the expression of pro‐inflammatory factors, and enhancing autophagy. [ABSTRACT FROM AUTHOR]

Objective: This study assessed the effect of cevimeline and different concentrations of gum arabic on the parotid gland of rats being given xerostomia-inducing methotrexate. Methods: One hundred twenty-five rats were divided into five equal groups of twenty-five each. The rats in Group I received basic diets, while those in Groups II, III, IV, and V received 20 mg/kg MTX as a single intraperitoneal dose on day one. Group III received 10 mg/kg CVM dissolved in saline orally and daily, and the other two groups received a 10% W/V aqueous suspension of GA. Therefore, Group IV received 2 ml/kg suspension orally and daily, while Group V received 3 ml/kg suspension orally and daily. After 9 days, the parotid glands were dissected carefully and prepared for hematoxylin and eosin (H&E) staining as a routine histological stain and caspase-3 and Ki67 immunohistochemical staining. Quantitative data from α-Caspase-3 staining and Ki67 staining were statistically analysed using one-way ANOVA followed by Tukey's multiple comparisons post hoc test. Results: Regarding caspase-3 and Ki67 immunohistochemical staining, one-way ANOVA revealed a significant difference among the five groups. For Caspase-3, the highest mean value was for group II (54.21 ± 6.90), and the lowest mean value was for group I (15.75 ± 3.67). The other three groups had mean values of 31.09 ± 5.90, 30.76 ± 5.82, and 20.65 ± 3.47 for groups III, IV, and V, respectively. For Ki67, the highest mean value was for group I (61.70 ± 6.58), and the lowest value was for group II (18.14a ± 5.16). The other three groups had mean values of 34.4 ± 9.27, 48.03 ± 8.40, and 50.63 ± 8.27 for groups III, IV, and V, respectively. Conclusion: GA, rather than the normally used drug CVM, had a desirable effect on the salivary glands of patients with xerostomia. [ABSTRACT FROM AUTHOR]