Streptozotocin-induced diabetic cystopathy in albino rat. An ultrastructural and immunohistochemical study

ABSTRACT

It was suggested that urinary bladder dysfunction can be considered as one of the most common complications of diabetes. Therefore, this study was designed to clarify the ultrastructural changes in the smooth muscles of the urinary bladder in diabetic rats and to ascertain the role of iNOS, in an attempt to investigate the possible mechanism of these histopathological changes. Thirty adult male albino rats were used in this study. The animals were divided into three equal groups; A served as sham-injected control, while the animals of group B were intraperitoneally injected with a single dose of streptozotocin [50 mg/kg body weight/ rat] and left under observation tor 8 weeks. The rats of group C were intraperitoneally-injected with the same dose of streptozotocin and left for 18 weeks. Specimens from the urinary of the animals of all groups were to obtain paraffin blocks which were cut and immunohistochamically stained for demonstration of iNOS activity. In addition, small specimens were processed and prepared for electron microscopic study. The smooth muscles cells showed progressive ultrastructural changes in the form of degenerated mitochondria, apparent increase in of the pinocytotic vesicles which were relatively electron lucent and degenerated in the cytoplasm that were devoid of actin and myosin filaments, in addition, corrugated cell membranes and widened gap junctions were observed. These myocytes showed strong positive reactions for iNOS as compared with the control group. The connective tissue stroma between adjacent cells showed degenerated nerve fibres forming myelin body-like structures, activated fibro-blasts with dilated endoplasmic reticulum cisternae and increased collagen deposition. These changes were more marked in the animals of the third group. Therefore, urinary bladder biopsy may be of value in early diagnosis of diabetic cystopathy with a more positive impact on management. Moreover, the increased iNOS expression can be considered as an indicator of oxidative stress and thus the use of antioxidants might have a role in better management of such condition