Hello All;
 
Further to the article in 'Nature', being published today.
A possible link between nicotine addiction and Parkinson's has been
discussed on the list before. I find this subject fascinating.
 
I've always thought that I was physically unable to be addicted to
either alcohol or nicotine, even long before Parkinson's made itself
known to me.
 
The 'pleasure enhancing chemical' aspects of dopamine are intriguing,
too. Does anyone have any further insight on this?
 
Poetic, humourous, or otherwise?
 
Janet
 
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Brain chemical said to play role in cigarette addiction
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Copyright ) 1996 Nando.net    Copyright ) 1996 N.Y. Times News Service
 
WASHINGTON (Feb 22, 1996 01:09 a.m. EST) -- Discovery of an important
biochemical difference in the brains of smokers suggests a new way,
independent of nicotine, in which smoking may become addictive.
 
The discovery concerns an enzyme that breaks down a pleasure-enhancing
chemical in the brain called dopamine. Using a technique for imaging
the living brain, researchers at the Brookhaven National Laboratory in
Upton,  N.Y., have found that the enzyme is 40 percent less active in
smokers, suggesting that dopamine levels would presumably be somewhat
higher.
 
The finding is of interest because dopamine levels are sharply
increased by addictive drugs like cocaine. It might also explain the
strange observation that smokers have only half the risk of
contracting Parkinson's disease, in which dopamine levels become
unusually depressed.
 
In a commentary published in the journal Nature on the research, Dr.
Alexander Glassman of Columbia University and Dr. George Koob of the
Scripps Research Institute in La Jolla, Calif., said the Brookhaven
results "open a new vista on the biological effects of cigarette
smoking."
 
Dr. Alan Leshner, director of the National Institute on Drug Abuse,
said the new study is important because it confirms the importance of
dopamine in cases of addiction to cigarettes, as well as cocaine,
heroin and other drugs.
 
"We know that every addictive substance causes an increase in dopamine
in the brain," Leshner said in an interview, "In the case of smoking,
this study tells us that we may have to go beyond our focus on
nicotine when looking at things that keep this addiction going."
 
The researchers said they have so far been unable to identify the
ingredient in tobacco smoke that inhibits the dopamine-destroying
enzyme, which is known as monoamine oxidase B or MAO B. Discovery of
the new MAO B mechanism, they said, may help in developing more
effective ways treat or block cigarette addiction.
 
Leshner said a truly effective treatment for smoking may have to be
directed at nicotine and the sites in the brain it affects, as well as
the dopamine system which appears to have an enhancing effect.
 
Dopamine is a chemical known as a neurotransmitter, one of many that
help brain cells communicate with one another. Nicotine is addictive
partly because it stimulates the release of dopamine as well as other
chemical messengers, whereas the new mechanism delays the breakdown of
dopamine.
 
"Our results suggest that whatever is inhibiting MAO B levels could be
acting together with nicotine to enhance dopamine's activity by
preventing it from breaking down," Dr. Joanna Fowler, the principal
researcher, said in an interview.
 
Results of the Brookhaven study also offer an explanation for a
mystery involving Parkinson's disease that has puzzled researchers for
years.
 
If smoking inhibits dopamine destruction, researchers said, this could
help stave off Parkinson's. The study also suggests that some drugs
used to treat Parkinson's disease might help in weaning smokers away
from cigarettes, much as nicotine patches and chewing gum do,
scientists said. Their report is published in the Feb. 22 issue of the
journal Nature.
 
"There are a number of MAO B-inhibiting drugs used to treat
Parkinson's disease that are relatively safe and well known," Dr.
Fowler said, "and we speculate that someone might try using them in a
program to break the habit of smoking."
 
The research, which was sponsored by the Department of Energy and the
National Institutes of Health, shows that nicotine is not the only
psychoactive component of cigarette smoke and that MAO B inhibition
may be involved in a tendency of certain people to have multiple
addictions.
 
There is a strong association between smoking and alcoholism, as well
as smoking and drug abuse in general and certain mental health
problems, such as depression. This could mean that cigarettes are a
"gateway" drug like marijuana that open a person to addictive behavior
involving other substances, the commentary said, raising added
concerns about adolescent exposure to smoking, Glassman and Koob said
in their Nature commentary.
 
Koob, an expert in psychopharmacology, said in an interview that it
should not be too difficult to find the agent in cigarette smoke that
depresses the MAO B enzyme. Finding this substance and ways to
manipulate it could have far reaching implications not only for
cigarette addiction, he said, but also for Parkinson's disease.
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Janet Paterson  -  48  -  7  -  [log in to unmask]  -  Bermuda