Effects of thymoquinone against angiotensin II-induced cardiac damage in apolipoprotein E-deficient mice

Herbal medicines have attracted much attention in recent years and are increasingly being used as alternatives to pharmaceutical medicines. Thymoquinone (TQ) is one of the most active ingredients in Nigella sativa seeds, which has several beneficial properties, including anti-inflammatory, anti-oxidative stress, anti-hypertensive, anti-apoptotic and free radical-scavenging effects. Angiotensin II (Ang II) is involved in cardiovascular diseases. The present study aimed to investigate the potential protective effects of TQ against Ang II-induced cardiac damage in apolipoprotein E-deficient (ApoE(−/−)) mice. Briefly, 8-week-old male ApoE(−/−) mice were randomly divided into four groups: Control, TQ, Ang II and Ang II + TQ groups. Osmotic minipumps, filled with either a saline vehicle or an Ang II solution (1,000 ng/kg/min), were implanted in ApoE(−/−) mice for up to 4 weeks. The serum levels of high-sensitivity C-reactive protein (hs-CRP) and histopathological alterations in heart tissue were assessed. In addition, the mRNA and protein expression levels of molecules associated with fibrosis (collagen I and III), oxidative stress and apoptosis (Nox4 and p53), and inflammation [tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6] were analyzed by reverse transcription-quantitative PCR (RT-qPCR) and western blotting. In the in vitro study, H9c2 cells were incubated with different concentrations of Ang II, and the expression levels of pro-inflammatory cytokines were evaluated using RT-qPCR, whereas the protein expression levels of phosphorylated-extracellular signal-regulated kinase (p-ERK) were determined using western blotting. Western blotting was also performed to detect the expression levels of collagen I, collagen III, Nox4 and p53 in H9c2 cells. The results revealed that TQ inhibited the Ang II-induced increases in serum hs-CRP levels. TQ also significantly inhibited the high levels of TNF-α, IL-1β, IL-6, collagen I, collagen III, Nox4 and p53 in Ang II-treated mice. Furthermore, TQ protected against Ang II-induced cardiac damage by inhibiting inflammatory cell infiltration, proinflammatory cytokine expression, fibrosis, oxidative stress and apoptosis by suppressing activation of the p-ERK signaling pathway. In conclusion, TQ could be considered a potential therapeutic agent for Ang II-induced cardiac damage.