Protein in a deadly spider's venom can be used to protect the human brain from stroke damage, according to a study.
Australian scientists say they found the Hi1a protein after "milking" the poisonous venom of funnel web spiders, which can kill within 15 minutes.
After injecting a version of the protein in lab rats, researchers found it blocked "acid-sensing ion channels" which are said to be the "key drivers" of brain damage after stroke.
The study said a dose of the compound two hours after a stroke reduced brain damage in rats by 80%. Even a dose after eight hours could cut injury by 65%, it added.
Professor Glenn King, who led the research, said it showed "great promise" as a future treatment.
He said: "During preclinical studies, we found that a single dose of Hi1a administered up to eight hours after stroke protected brain tissue and drastically improved neurological performance.
"This world-first discovery will help us provide better outcomes for stroke survivors by limiting the brain damage and disability caused by this devastating injury."
Hi1a came to the attention of scientists as it looked like two copies of another chemical that can protect brain cells.
Prof King added: "Hi1a even provides some protection to the core brain region most affected by oxygen deprivation, which is generally considered unrecoverable due to the rapid cell death caused by stroke."
The research team from the University of Queensland and Monash University has not yet conducted human trials, but is raising money to fast-track its progress.
Dr Kate Holmes, deputy director for research at the Stroke Association, said it is unknown whether the protein could be used in treatments for humans in the future.
She said: "We welcome any treatment that has the potential to reduce the damage caused by stroke, particularly if this can benefit people who are unable to arrive at hospital quickly.
"Current treatments must be given in half this time period, and it is too early for us to know if this research can offer an alternative for stroke patients."
Strokes occur more than 100,000 times a year in the UK.
The condition is the country's fourth single leading cause of death, while two-thirds of survivors leave hospital with a disability.