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.