Histopathological effect of hypervitaminosis D3 on the submandibular salivary gland of albino rats and the possible protective role of vitamin K “histological & ultrastructural study”

Abstract Background This study was designed to inspect the effects of vitamin D 3 overdose on the submandibular salivary gland of Albino rats and to investigate the possible protective role of vitamin K 1 after one month, as few studies have addressed its histopathological effects. Methods This study was carried out on 60 adult male Albino rats, and they were divided into three groups. Group I (control): received physiological saline. Group II (vitamin D 3 overdose): received 1 ml/kg/day cholecalciferol (200 IU) for 30 days. Group III (vitamin D 3 + vitamin K 1 ): received the same vitamin D 3 dose plus vitamin K 1 (15 mg/kg/day) for 30 days. Blood samples were analyzed for baseline and terminal levels of total and ionized calcium. Specimens were examined using Hematoxylin and eosin, alizarin red stain, transmission electron microscopes, and histomorphometric analysis. Statistical analysis was performed using analysis of variance, followed by a post hoc test for pairwise comparisons, and paired t-test for intra-group comparison between baseline and terminal values. Results examination of group II revealed pronounced structural alterations, notably acinar atrophy, which was statistically validated by a significant reduction in acinar circumference (p-value = 0.024*), alongside ductal degeneration, vascular congestion, and tissue calcification as detected by alizarin red stain. These histopathological changes correlated with elevated serum calcium levels ( p -value = 0.001**). In contrast, co-treatment with vitamin K 1 in group III substantially mitigated these pathological effects, demonstrating preservation of acinar and ductal structures, attenuation of calcific deposits, and partial normalization of serum calcium levels ( p -value = 0.004*). Conclusions Chronic administration vitamin D₃ overdose triggered degenerative, inflammatory, and calcific changes in the SMG. Also, co-administration of vitamin K 1 diminished vitamin D 3 -induced histopathological changes and hypercalcemia.