SCIENTISTS 'BREAK DRUG ADDICTION LINK'

French scientists yesterday announced the discovery of a
ground-breaking substance that significantly dampens drug cravings in
rats and could eventually shield former heroin, alcohol or tobacco
addicts from the temptation of taking up their habit again.

There is a very strong parallel between the animal model we used
and what is observed in humans, said Pierre Sokoloff, who heads the
team from the National Health and Medical Research Institute in Paris.
From the animal studies we have done, I have to say that we are
very optimistic.

One of the biggest problems for hardened addicts who are trying to
give up and even those who managed to kick their habit are the
powerful cravings triggered by visual cues like the sight of a small
pile of white powder, a syringe or a cup of after dinner coffee.

The Paris team found that the new molecule, known as BP 897,
drastically reduced the desire for cocaine in addicted laboratory rats
who had been trained to associate the drug with just such a signal.

"Our rats were conditioned to expect a bright light to come on
whenever they stepped on a little lever to take a dose of cocaine," Mr
Sokoloff said. "After a while, when the light came on but no drugs
were available, the rats began to display classic dependent behaviour.
The way they behaved when shown the light was a fair measure of their
craving."

But rats that had been given the BP 897 molecule "were far less
interested in looking for cocaine", he said. "Those that hadn't been
given BP 897, on the other hand, continued to search
compulsively."

BP 897 works on the same brain receptor as dopamine, a chemical that
is normally secreted and re-absorbed by brain cells and has long been
associated with pleasure and euphoria. Many addictive drugs work by
blocking the re-absorption of dopamine, a process which is thought to
be responsible for the cravings - the anticipation of a reward, or
high, from taking the drug - that are experienced by so many former
addicts.

"Every product that induces dependence in humans, whether it is
cocaine, morphine, even nicotine or alcohol, stimulates the retention
of dopamine in this area of the brain," Mr Sokoloff said. "Since BP
897 acts on the common mechanism that leads to every form of drug
abuse, we have no reason to believe it won't also be useful in
treating tobacco or heroin addiction."

Unlike other substances such as methadone, BP 897 does not act as a
replacement for the addictive drug, nor is it addictive. The
researchers, who published details of the discovery in yesterday's
Nature magazine, said tests indicate that BP 897 would have limited
side effects.