Vitamin C Mitigates Radiation-Induced Parotid Glands Inflammation by Downregulating TNF-α and IL-1β Expression in Guinea Pigs

Background: Radiation therapy damages surrounding tissues, with parotid glands being highly vulnerable in the head and neck region. Antioxidant and anti-inflammatory properties of vitamin C may reduce radiation-induced injury. This study therefore investigated the impact of vitamin C on morphological and histological changes in guinea pig parotid glands and its impact on tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) expression.Method: 48 Dunkin Hartley guinea pigs (6-8 months, both sexes) were divided into four groups: control, vitamin C (3 mg/kg), radiation 8 Grays (Gys), and radiation + vitamin C. Animals were treated with radiation and/or vitamin C for 15 days on alternate days. Weight and saliva volume were measured on alternate days too. Parotid glands were extracted for histological and immunohistochemical analysis of TNF-α and IL-1β. Data were analyzed using SPSS (version 21) and presented as mean ± standard error of mean. One-way ANOVA with Bonferroni’s post hoc test was applied, with P < 0.05 considered significant.Results: Over 15 days, no significant differences in animal weight were observed (P > 0.05). However, a significant reduction in saliva production occurred in the radiation group, alleviated by vitamin C (P < 0.05). Histological analysis showed radiation-induced inflammation in the parotid glands, which was diminished by vitamin C. Immunohistochemistry revealed a significant increase in TNF-α and IL-1β expression in the radiation group (P < 0.001), with vitamin C significantly downregulating both markers in the radiation + vitamin C group (P < 0.001).Conclusion: Vitamin C may protect against radiation-induced parotid gland inflammation by downregulating TNF-α and IL-1β, suggesting its potential as a therapy for radiation-induced tissue injury.