Effects of streptozotocin-induced diabetes on lingual histological changes in the rats.

ABSTRACT

Background: Many studies suggest that taste disorders and tongue lesions associate with diabetes mellitus (DM). However, the lingual histopathology underlying impairments in taste sensation, swallowing and speaking in the DM is poorly examined. Objective: The present study aimed to clarify histological changes of the tongues in streptozotocin (STZ)-induced diabetic and control rats by using light microscopy. Materials and Methods: Eight male adult Sprague-Dawley rats; five STZ (60 mg/kg)-induced diabetic and three control rats, were studied. At 24 weeks after the induction, tongues were collected and processed by conventional histological technique with Masson’s trichrome staining. Results: In the DM, thickness of epithelium reduced, whereas that of keratin raised. Moreover, loss of characteristic layering was found. These cells became loss of chromatin. Furthermore, total numbers of taste buds in all types of lingual papillae per a tongue significantly decreased, when compared to those in the control. In both diabetic lamina propria and muscular layer, there were collagen fibers accumulations, numerous inflammatory cells, and swollen endothelial cells with narrowing of capillary lumen. In the muscular layer, average sizes of intrinsic skeletal muscle cells in all zones of diabetic tongue were significantly smaller than those in the control. Conclusion: It is possible that changes in histological characteristics of the tongue are important mechanisms underlying the development of taste disorders, impairments of swallowing and speaking in diabetic patients.