RESUMO
Hyperthyroidism is a condition resulting from hypersecretion of thyroid hormones [T3 and T4]. It affects multiple organ systems, including the renal system. This study was set to evaluate the protective effect of Hibiscus sabdariffa [roselle] on the damaging effect induced by hyperthyroid state in the rat renal cortex. Twenty-four adult male albino rats were used and divided into four groups of six rats each. Group I was the control group. In group II, the rats received aqueous extracts of roselle at a daily dose of 500 mg/kg body weight. In group III, the rats were given a daily oral dose of thyroxin [100 micro g/kg body weight] dissolved in distilled water through gavage for 1 month. In group IV, the rats were given an aqueous extract of roselle at a daily dose of 500 mg/kg body weight 3 h before thyroxin administration at 100 micro g/kg body weight. At the end of the experimental period, blood samples wer collected for thyroid hormone [T3 and T4] assay. Kidney specimens were processed for immunohistochemical and histological study using light and electron microscopes. Morphometric analysis of the proximal convoluted tubule [PCT] diameter was carried out. A statistically significant elevation in the levels of T3 and T4 was observed in the thyroxin-treated group. Also, a significant increase in the diameter of PCT was detected in this group. Histologically, some malpighian corpuscles were partially atrophied. Effacement of podocyte foot processes with thickening of the filtration barrier was observed. In addition, tubulointerstitial injury in the form of PCT dilatation, peritubular hemorrhage, and inflammatory cellular infiltration was also seen. Immunohistochemical examination of the thyroxin-treated group revealed excess actin fibers in the PCT cells, indicating exposure of these cells to stress. Furthermore, there was significant improvement in the histological and immunohistochemical pictures toward normal in the thyroxin and roselle-treated group. Roselle has a potent protective effect against the damaging effect induced by the hyperthyroid state in the rat renal cortex