Escin alleviates stress-induced intestinal dysfunction to protect brain injury by regulating the gut-brain axis in ischemic stroke rats

Hyperactivity of HPA axis results in intestinal dysfunction, which may play a role in brain injury caused by ischemic stroke (IS). Escin shows a neuroprotective effect but it may not penetrate blood brain barrier (BBB). Previous work in our laboratory showed that escin ameliorated intestinal injury in animals. The aim of this study is to investigate whether escin attenuates brain injury by improving intestinal dysfunction in middle cerebral artery occlusion (MCAO) rats, to mimic IS. MCAO rats and lipopolysaccharides (LPS)-induced Caco-2 cells were used to evaluate the effects of escin in vivo and in vitro. The results showed that escin could not penetrate BBB but reduced brain infarct volume, improved neurological function, inhibited neuroinflammation, ameliorated intestinal dysfunction and tissue integrity by increasing the expression of the tight junction protein in vivo and in vitro. Escin reduced the increased corticosterone and endotoxin level in blood of MCAO rats, regulated GR/p38 MAPK/NF-κB signaling pathway in ileal tissue and LPS/TLR4/NF-κB signaling pathway in ischemic brain tissue. These findings suggest that escin could attenuate ischemic brain injury by improving intestinal dysfunction, and it may be a promising way to protect brain injury by protecting intestine, instead of targeting the brain directly after IS.