Australian scientists have discovered a drug that may have the potential to reduce, and even stop, the effects of stroke.
Trials on mice show the drug, which mimics some actions of oestrogen, protects females against stroke, while worsening the condition in males.
But, on the other hand, blocking an oestrogen receptor in males could alleviate the symptoms of stroke if administered within four hours, Monash University researchers said.
About 50,000 Australians suffer strokes each year. Aside from a clot-busting drug, there are limited treatments. About one-third of people who have a stroke die from it, another third recover fully and one-third survive but remain dependent on care.
While hundreds of clinical trials have failed to find new treatments, researchers at the Monash school of biomedical sciences have found that the recently discovered oestrogen receptor that occurs in both men and women plays a role in the severity of a stroke.
During the trials in mice, they found by blocking this oestrogen receptor in males they could alleviate the symptoms of stroke, while triggering the receptor with a drug in older females protected them from harmful effects of stroke.
Lead researcher Chris Sobey said targeting the receptor GPER in younger females had no effect, suggesting they already had enough oestrogen naturally present in their bodies. He said the findings, published in the journal Stroke this week, could lead to sex-specific treatments for stroke - Australia's second biggest killer after coronary heart disease and a leading cause of disability.
''We don't really understand the mechanisms yet but it's a very profound sex difference, so it could mean that when a male comes into emergency with a stroke, he could be given the receptor blocker and when a woman comes in, she could be given an activator of the receptor,'' he said. ''Based on our experiments, we predict both will be beneficial.''
Associate Professor Sobey said the findings might help to explain why strokes were more common in men up until the age of 75 because women had naturally higher levels of oestrogen - the primary female sex hormone - up until menopause. After 75, the rate of stroke was similar in men and women but after 85, women tended to experience strokes more than men.
Associate Professor Sobey said his team planned more animal trials to better understand the mechanisms and refine dosing in the hope of human trials in coming years.
''There are basically no treatments for stroke at the moment,'' he said. ''All we really have is a clot busting drug that can only be given within 4½ hours of a stroke and even then you require a scan before that to make sure it's not a bleed, because if it is the drug will make it worse. So any new finding with the potential for therapy in the clinic is of great interest.''