Researchers in Hong Kong report that the hormone melatonin, more commonly used to reduce the effects of jetlag, could protect the brain from the effects of stroke.
They say that an injection of melatonin (5g/kg) given within two hours of the stroke can reduce the amount of damage to the brain tissue.
Recent research has shown that melatonin may also protect against stroke. However researchers wanted to assess the benefits of the hormone, produced by the pineal gland in the brain, when taken after the stroke started.
The team from the Faculty of Medicine, University of Hong Kong, gave adult rats an injection of melatonin immediately, one or three hours after the beginning of stroke. Other groups received multiple injections of melatonin at 5 mg/kg with the first injection given at one, two, or three hours after onset of ischemia and the second and third injections at 24 and 48 hours, respectively. A control group received empty injections.
Reporting in the journal Stroke, the researchers said that a single dose of melatonin at 5 mg/kg given immediately or one but not three hours after onset of ischemia reduced the infarct volume (area of tissue death). Multiple doses of melatonin at 5 mg/kg also reduced the infarct volume when the first dose was given at one or two but not three hours after onset.
Melatonin is widely available in the US, and some other countries such as Thailand and Singapore, as a 'dietary supplement' but in Europe and many other countries it is regulated as a medicine and requires a licence. It is difficult to obtain in these countries.