Hydroxysafflor Yellow A Alleviates Ischemic Stroke in Rats via HIF-1 alpha, BNIP3, and Notch1-Mediated Inhibition of Autophagy

Stroke has become a major cause of death and disability worldwide. The cellular recycling pathway autophagy has been implicated in ischemia-induced neuronal changes. but whether autophagy plays a beneficial or detrimental role is controversial. Hydroxysafflor Yellow A (HSYA), a popular herbal medicine, is an extract of Carthamus tinctorius and is used to treat ischemic stroke (IS) in China. HSYA has been shown to prevent cardiovascular and cerebral ischemia/reperfusion injury in animal models. However, the specific active ingredients and molecular mechanisms of HSYA in IS remain unclear. Here, we investigated the effect of HSYA treatment on autophagy in a rat model of IS. IS was induced in rats by middle cerebral artery occlusion. Rats were treated once daily for 3 days with saline. HYSA. or the neuroprotective agent Edaravone. Neurobehavioral testing was performed on days 1. 2, and 3 post-surgery. Brains were removed on day 3 post-surgery for histological evaluation of infarct area, morphology, and for qRT-PCR and western blot analysis of the expression of the autophagy factor LC3 and the signaling molecules HIF-1 alpha. BNIP3, and Notch1. Molecular docking studies were performed in silico to predict potential interactions between HSYA and LC3, FIEF-1 alpha, BNIP3, and Notch1 proteins. The result showed that HSYA treatment markedly alleviated IS-induced neurobehavioral deficits and reduced brain infarct area and tissue damage. HSYA also significantly reduced hippocampal expression levels of LC3. HIF-1 alpha, BNIP3, and Notch1. The beneficial effect of HSYA was generally superior to that of Edaravone. Molecular modeling suggested that HSYA may bind strongly to HIF-1 alpha, BNIP3, and Notch1 but weakly to LC3. In conclusion, HSYA inhibits post-IS autophagy induction in the brain, possibly by suppressing HIF-1 alpha, BNIP3 and Notch1. HSYA may have utility as a post-IS neuroprotective agent.