Thymoquinone protects the rat kidneys against renal fibrosis

Thymoquinone (TQ) is the main active ingredient of Nigella sativa seeds with various pharmacological effects. The aim of this study was to investigate the effect of TQ on renal fibrosis and permeability and oxidative stress status in lipopolysaccharide (LPS)-induced inflammation in male rats. Eighty male Wistar rats were divided into 5 groups as follow: control (received normal saline), LPS (1 mg/kg/day), and LPS+TQ (by doses of 2, 5 and 10 mg/kg/day). After three weeks, the biochemical parameters such as blood urea nitrogen (BUN) and creatinine in serum samples, oxidative stress markers including malondialdehyde (MDA), total thiol groups, superoxide dismutase (SOD) and catalase (CAT) activities in renal tissue homogenate and renal permeability (evaluated by Evan's blue dye method) were measured and renal fibrosis was evaluated, histologically using Masson's trichrome staining. LPS administration induced renal fibrosis (1.49 ± 0.08 vs. 7.15 ± 0.18%) and significantly increased renal permeability (6.03 ± 1.05 vs. 13.5 ± 1.04 μg evans blue(EB)/g tissue), serum BUN and creatinine levels and oxidative stress marker (MDA) (P < 0.05), while, it reduced anti-oxidative markers including total thiol group, SOD and CAT activities (P < 0.05). Administration of TQ significantly improved these alterations which were dose-dependent in oxidative stress markers, renal permeability (TQ 2, 5 and 10 mg/kg: 10.7 ± 0.3, 9.2 ± 1.4 and 11.5 ± 0.6 μg EB/g tissue; respectively) and fibrosis (TQ 2, 5 and 10 mg/kg: 6.09 ± 0.7, 4.26 ± 0.14 and 2.52 ± 0.08%; respectively). In conclusion, administration of TQ reduced renal fibrosis and permeability and improved oxidative stress status. Thus, TQ can be considered in conditions accompanied with chronic inflammation at least as a part of treatment strategy.