XingNaoJing injection ameliorates cerebral ischaemia/reperfusion injury via SIRT1-mediated inflammatory response inhibition

XingNaoJing injection (XNJ), extracted from a traditional compound Chinese medicine Angong niuhuang pill, is well known for treating stroke in the clinic, but the specific effects and mechanisms remain unclear. We investigated the mechanistic basis for the protective effect of XNJ on cerebral ischaemia/reperfusion (I/R) injury. Five groups of 10 SD rats underwent 2 h of middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. XNJ at 10 and 15 mL/kg was intraperitoneally administered 24 h before ischaemia and at the onset of reperfusion respectively. The silent information regulator 1 (SIRT1) inhibitor EX527 was intracerebroventricularly injected 0.5 h before reperfusion. Cerebral infarction size, neurological scores, morphological changes, and expression levels of inflammatory mediators and SIRT1 were measured. Furthermore, human brain microvascular endothelial cells (HBMECs) were subjected to 3 h oxygen and glucose deprivation (OGD) followed by 24 h reoxygenation to mimic cerebral I/R in vitro. EX527 pre-treatment occurred 1 h before OGD. SIRT1 and inflammatory mediator levels were analyzed. Both XNJ doses significantly decreased cerebral infarct area (40.11% vs. 19.66% and 9.87%) and improved neurological scores and morphological changes. Inflammatory mediator levels were remarkably decreased in both model systems after XNJ treatment. XNJ also enhanced SIRT1 expression. Notably, the SIRT1 inhibitor EX527 attenuated the XNJ-mediated decrease in inflammation in vivo and in vitro. XNJ improved cerebral I/R injury through inhibiting the inflammatory response via the SIRT1 pathway, which may be a useful target in treating cerebral I/R injury.