Thymoquinone supplementation attenuates hypertension and renal damage in nitric oxide deficient hypertensive rats

The present study was undertaken to evaluate the protective effect of thymoquinone (TQ), the main constituent of the volatile oil from Nigella sativa seeds, in rats after chronic inhibition of nitric oxide synthesis with N(omega)-nitro-l-arginine methyl esters (l-NAME). Rats were divided randomly into different treatment groups: control, l-NAME, TQ and l-NAME + TQ. Hypertension was induced by 4 weeks administration of l-NAME (50 mg/kg/day p.o.). TQ was administered alone or in combination with l-NAME and continued for 4 weeks. The animals were killed, and the serum and kidney tissues were isolated for the determination of creatinine and glutathione (GSH), respectively. Rats receiving l-NAME showed a progressive increase in systolic blood pressure compared with control rats. Concomitant treatment with TQ (0.5 and 1 mg/kg/day p.o.) reduced the increase in systolic blood pressure induced by l-NAME in a dose dependent manner. Kidney injury was demonstrated by a significant increase in serum creatinine and a decrease in GSH in kidney tissue from l-NAME treated rats. Treatment of rats with TQ decreased the elevated creatinine and increased GSH to normal levels. TQ inhibited the in vitro production of superoxide radical in enzymatic and non-enzymatic systems. In conclusion, TQ is effective in protecting rats against l-NAME-induced hypertension and renal damage possibly via antioxidant activity.