Amino Acids May Have Protective Effects on Salivary Glands of 5-FU-administered Mice

Protective Effect of Electroacupuncture on Chemotherapy-Induced Salivary Gland Hypofunction in a Mouse Model

Radiotherapy and chemotherapy can impair salivary gland (SG) function, which causes xerostomia and exacerbate other side effects of chemotherapy and oral infection, reducing patients' quality of life. This animal study aimed to assess the efficacy of electroacupuncture (EA) as a means of preventing xerostomia induced by 5-fluorouracil (5-FU). A xerostomia mouse model was induced via four tail vein injections of 5-FU (80 mg/kg/dose). EA was performed at LI4 and LI11 for 7 days. The pilocarpine-stimulated salivary flow rate (SFR) and salivary glands weight (SGW) were recorded. Salivary immunoglobulin A (SIgA) and lysozyme were determined via enzyme-linked immunosorbent assay (ELISA). SG was collected for hematoxylin and eosin staining to measure acini number and acinar cell size. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and aquaporin 5 (AQP5) mRNA expressions in SG were quantified via RT-qPCR. 5-FU caused significant decreases in SFR, SGW, SIgA, lysozyme, AQP5 expression, and acini number, while TNF-α and IL-1β expressions and acinar cell size were significantly increased. EA treatment can prevent 5-FU damage to the salivary gland, while pilocarpine treatment can only elevate SFR and AQP5 expression. These findings provide significant evidence to support the use of EA as an alternative treatment for chemotherapy-induced salivary gland hypofunction and xerostomia.

An elemental diet protects mouse salivary glands from 5‑fluorouracil‑induced atrophy

An elemental diet (ED) reduces adverse effects of chemotherapy, including oral mucositis, in patients with cancer. However, the detailed mechanism(s) of the healing effects of an ED remains unclear. In the present study, the protective effects of the ED, Elental^®, were examined against 5-fluorouracil (5-FU)-induced oral mucositis and salivary gland atrophy in mice. Mucositis was induced in female ICR mice by injection of 5-FU. The mice were orally administered Elental^® (ED group) or saline (control group). After treatment, the mice body weight, salivary gland weight and the histological changes in the salivary gland granular duct area were monitored. The mice body weight remained stable in the ED group, but was significantly decreased in the control group. Moreover, the salivary gland weight was higher in the ED group compared with the control group. In addition, the salivary gland granular duct area cells were larger in the ED group compared with the control group. Whole transcriptome analysis and network analysis were conducted to understand the mechanisms of action of Elental^® against oral mucositis. Whole transcriptome analysis and Ingenuity Pathways Analysis data suggested that Elental^® contributed to the recovery of mitochondrial function in 5-FU-damaged salivary glands. Immunohistochemical analysis of salivary gland tissue demonstrated that the expression of cytochrome c oxidase subunit 4 and epidermal growth factor were higher in the ED group compared with the control group. Next, the rate of apoptosis in the salivary glands was examined using terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assays. The number of TUNEL-positive cells in the salivary glands was lower in the ED group compared with the control group. These findings suggested that Elental^® may protect mouse salivary glands from 5-FU-induced atrophic changes, which suggests that ED treatment may improve xerostomia and alleviate oral mucositis in patients with cancer receiving 5-FU-based chemotherapy.

Xanthine Oxidase Inhibitor, Febuxostat Is Effective against 5-Fluorouracil-Induced Parotid Salivary Gland Injury in Rats Via Inhibition of Oxidative Stress, Inflammation and Targeting TRPC1/CHOP Signalling Pathway

The current research aimed to examine the ameliorative role of febuxostat (FEB), a highly potent xanthine oxidase inhibitor, against 5-fluorouracil (5-FU)-induced parotid salivary gland damage in rats, as FEB is a pleiotropic drug that has multiple pharmacological effects. A total of 32 Wistar adult male rats were randomly arranged into four groups. Group 1: the control group; given only the vehicle for 14 days, then given a saline i.p. injection from the 10th to the 14th day. Group 2: the FEB group; rats received FEB (10 mg/kg) once daily po for 14 days before receiving a saline i.p. injection from the 10th to the 14th day. Group 3: the 5-FU group; from the 10th to the 14th day, rats received an intraperitoneal injection of 5-FU (35 mg/kg/day). Group 4: the FEB/5-FU group; rats were pre-treated with FEB po for 14 days before receiving 5-FU i.p injections for five consecutive days from the 10th to the 14th day. Parotid gland damage was detected histologically and biochemically by the evaluation of oxidative stress markers (malondialdehyde (MDA) and nitric oxide levels (NOx)), oxidant defences (reduced glutathione (GSH) and superoxide dismutase (SOD)), inflammatory markers (tumour necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β)), and transient receptor potential canonical1 (TRCP1) and C/EBP homologous protein (CHOP). FEB pre-treatment reduced MDA, TNF-, and IL-1 while increasing SOD, GSH, and NOx. FEB also significantly increased TRPC1 and decreased CHOP in parotid gland tissue. In conclusion, FEB pre-treatment reduced 5-FU-induced parotid salivary gland damage not only through its powerful anti-inflammatory and antioxidant effects, but also through its effect on the TRPC1/CHOP signalling pathway.