Abstract
BACKGROUND Isorhamnetin is a natural flavonoid compound with anti-inflammatory and antioxidant properties. However, its roles in alleviating lung injury associated with heatstroke remain unclear. Therefore, this study aimed to evaluate the protective effects of different isorhamnetin doses on lung injury in heatstroke rat models exposed to a dry-heat environment. MATERIAL AND METHODS Fifty Sprague-Dawley rats were randomly divided into 5 groups: normal control (0.9% saline), heatstroke (0.5% CMCNa), and isorhamnetin (25, 50, and 100 mg/kg) groups; treatments were administered by gavage daily for 7 days. All rats, except those in the control group, were exposed to a dry-heat environment (41±1°C, 10±2% relative humidity) for 150 min to induce heatstroke. Pathological changes, ultrastructure, edema, inflammation, and oxidative stress in the lungs were assessed. RESULTS Compared with the heatstroke group, rats treated with 100 mg/kg isorhamnetin showed amelioration of histopathological and ultrastructural changes in the lungs; decreased lung injury scores (P<0.05) and wet/dry weight ratios (P<0.01); lower levels of phospho-nuclear factor-kappaB (P<0.05), high-mobility group box 1 (P<0.01), tumor necrosis factor-alpha (P<0.01), interleukin (IL)-1ß (P<0.01), and IL-6 (P<0.01); lower malondialdehyde contents (P<0.01); and higher superoxide dismutase (P<0.01) and catalase activities (P<0.05). CONCLUSIONS In a dry-heat environment, isorhamnetin protected against lung injury in heatstroke rat models via anti-inflammatory and anti-oxidative mechanisms.