This study aimed to evaluate the toxic effect of silver nanoparticles (AgNPs) on the parotid glands (PGs) of albino rats histologically and ultrastructurally and assess the possible protective effect of ascorbic acid as an antioxidant. Thirty male albino rats weighing between 150 mg and 200 mg were divided into three groups: the control group (C1) contained 10 rats that received 2 mg/kg (body weight (bw)) of aqueous nitrate buffer by intraperitoneal (IP) injection daily for 28 days; the AgNPs group contained 10 rats that received 2 mg/kg (bw) IP AgNPs daily for 28 days; and the AgNPs-vitamin C group contained 10 albino rats that received 2 mg/kg (bw) AgNPs IP daily for 28 days with oral administration of 100 mg/kg (bw) vitamin C in drinking water daily for 28 days. The PG acinar and ductal cells of the AgNPs group showed signs of toxicity and degeneration characterized as pleomorphic nuclei, binucleation, cytoplasmic vacuolations, and stagnated secretion in the ductal lumen. In addition to degenerated mitochondria, dilated rough endoplasmic reticulum and lysosomes were filled with AgNPs ( p < 0.001). The AgNPs-vitamin C group showed significantly less degenerative changes histologically and ultrastructurally compared to the AgNPs group ( p = 0.002). AgNPs produced significant toxic effects on the PG of albino rats, presumably through the generation of reactive oxygen species and toxic ion release, and administration of vitamin C was shown effective in decreasing these toxic effects.

Objective: Head and neck cancer is the sixth leading cancer by incidence worldwide and eighth by death. Recent reports revealed that, not only radiotherapy but also chemotherapy may induce xerostomia. The aim of this study was to compare the possible regenerative effect of BMSCs through systemic and local injections. Material and Methods: 52 male Albino rats were randomly divided into 4 groups: Group 1: 10 rats received 0.5 ml of PBS by injection. Group 2: 14 rats received an intraperitoneal injection of 5-FU drug. Group 3: 14 rats were injected the same dose of 5-FU then received an intraglandular transplantation of BMSCs suspended in 0.5 ml of PBS at day 1 after 5-FU administration. Group 4: 14 rats were injected the same dose of 5-FU then received an intravenous injection of BMSCs suspended in 0.5 ml of PBS via the tail vein at day 1 after 5-FU administration. Results: Histological examination showed that group 2 showed features of severe degenerative changes which increased over time. Group 3 showed increasing amelioration in the ductal structure overtime. Group 4 also showed regenerated ductal elements however concerning apoptotic changes, immunohistochemistry results revealed improvement in both group 3 and 4 over group 2 with no statistical difference between groups 3 and 4. Conclusion: Histological and immunohistochemical features in group 3 and group 4 revealed similar amelioration in regenerative potentials. On the other hand, regenerative features of both experimental groups were statistically significant as compared independently to group 1. KEYWORDS 5-fluourouracil; anti-caspase-3; BMSCs; H&E; parotid salivary gland. RESUMOObjetivo: O carcinoma de cabeça e pescoço é o sexto câncer de maior incidência no mundo sendo a oitava causa de morte por cancer. Relatos recentes revelaram que não apenas a radioterapia, mas também a quimioterapia podem induzir xerostomia. O objetivo desse estudo foi comparar a possivel ação regenerative de BMSCs através de injeção local e sistêmica. Material e Métodos: 52 ratos Albino foram aleatoriamente alocados em 4 grupos: Grupo 1: 10 ratos que receberam 0.5 ml de injeção de PBS. Grupo 2: 14 ratos que receberam injeção intraperitoneal da droga 5-FU. Grupo 3: 14 ratos que foram injetados com a mesma dose de 5-FU e receberam transplante intraglandular de BMSCs ressuspendidas em 0.5mL de PBS no dia 1 após a administração do 5-FU. Grupo 4: 14 ratos que foram injetados com a mesma dose de 5-FU e receberam injeção intravenosa de BMSCs ressuspendidas em 0.5mL de PBS via veia caudal 1 dia após a administração de 5-FU. Resultados: O exame histológico demonstrou que o grupo 2 apresentou alterações degenerativas severas que se agravaram com o tempo. O Grupo 3 mostrou melhora da estrutura ductal ao longo do experimento. Group 4 também mostrou elementos ductais regenerados. Referente a alterações apoptóticas,análise imunohistoquimica mostrou melhora nos grupos 3 e 4 comparados ao grupo 2, sendo que os grupos 3 e 4 foram estatisticamente semelhantes. Conclusão: Análises histológicas e imun...