Dec. 13, 2006 Scientists at Melbourne's Howard Florey Institute have discovered a system in the brain that stops an alcoholic's craving for alcohol, as well as prevent relapse once they have recovered from alcohol addiction.
The 'Orexin' system is a group of cells in a part of the brain called the hypothalamus. These cells produce Orexin, which was originally implicated in the regulation of feeding, but it soon became apparent that Orexin was also involved in the 'high' felt after drinking alcohol or taking illicit drugs.
In studies conducted with rats, Dr Andrew Lawrence and his Florey colleagues used a drug that blocked Orexin's euphoric effects in the brain and the results were remarkable.
"In one experiment, rats that had alcohol freely available to them stopped drinking it after receiving the Orexin blocker." Dr Lawrence said.
"In another experiment, rats that had gone through a detox program and were then given the Orexin blocking drug, did not relapse into alcohol addiction when they were reintroduced to an environment in which they had been conditioned to associate with alcohol use.
"Orexin reinforces the euphoria felt when drinking alcohol, so if a drug can be developed to block the Orexin system in humans, we should be able to stop an alcoholic's craving for alcohol, as well as preventing relapse once the alcoholic has recovered," he said.
Dr Lawrence said that this research could also lead to treatments for eating disorders, such chronic over-eating, which leads to obesity.
"Our research shows that alcohol addiction and eating disorders set off common triggers in the brain, so further investigations may uncover drug targets in the Orexin system to treat both conditions," Dr Lawrence said.
The Florey scientists are now conducting multiple experiments to discover the precise circumstances that activate the Orexin system.
"To explore this discovery further we are now investigating how different experimental paradigms and environmental situations impact on the Orexin system, which will hopefully pinpoint therapeutic drug targets," Dr Lawrence said.
"Before a therapeutic Orexin-blocking drug can be developed, we need to ensure that it will be safe to use in the long-term and that issues surrounding a person's compliance in taking the drug are considered," he said.
According to the World Health Organisation, alcohol is one of the most widely used and abused substances in the world and causes as much, if not more death and disability as measles, malaria, tobacco, or illegal drugs.
Dr Lawrence and his colleagues were the first in the world to demonstrate the Orexin system's involvement in alcohol addiction and their research paper was recently published in the prestigious British Journal of Pharmacology. Dr Lawrence's paper was downloaded 658 times by researchers from around the world in the first three months of its publication, making it the most downloaded research paper in that issue and supporting the research's importance.
The Howard Florey Institute is Australia's leading brain research centre. Its scientists undertake clinical and applied research that can be developed into treatments to combat brain disorders, and new medical practices. Their discoveries will improve the lives of those directly, and indirectly, affected by brain and mind disorders in Australia, and around the world. The Florey's research areas cover a variety of brain and mind disorders including Parkinson's disease, stroke, motor neuron disease, addiction, epilepsy, multiple sclerosis, autism and dementia.
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