Posted by Ron Hill on June 10, 2003, at 19:34:15
In reply to Re: Nicotine and brain chemicals, posted by samplemethod on June 10, 2003, at 6:30:52
Sample,
> I would be interested in finding scientific evidence that nicotine is a MAO-B inhibitor. My impression was the cigarettes, or more correctly something within the cigarettes when smoked, actually affects MAO-B. It may well be nicotine, but I havent seen any proof of that yet.
According to this study, it's not nicotine; it's 2-Naphthylamine. It's also a carcinogen.
2-Naphthylamine, a compound found in cigarette smoke, decreases both monoamine oxidase A and B catalytic activity.
Hauptmann N, Shih JC.
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles, USA. hauptman@neotherapeutics.com
Cigarette smokers exhibit a lower monoamine oxidase (MAO; EC 1.4.3.4) activity than nonsmokers. MAO is located in the outer membrane of mitochondria and exists as two isoenzymes, MAO A and B. MAO A prefers 5-hydroxytryptamine (serotonin), and MAO B prefers phenylethylamine (PEA) as substrate. Dopamine is a substrate for both forms. 2-Naphthylamine is a carcinogen found in high concentrations in cigarette smoke. The results of this study show that 2-naphthylamine has the ability to inhibit mouse brain MAO A and B in vitro by mixed type inhibition (competitive and non-competitive). The Ki for MAO A was determined to be 52.0 microM and for MAO B 40.2 microM. The inhibitory effect of 2-naphthylamine on both MAO A and B catalytic activity, supports the hypothesis that smoking decreases MAO activity in vivo, instead that smokers with lower MAO activity are more prone to become a smoker.
PMID: 11233991 [PubMed - indexed for MEDLINE]
poster:Ron Hill
thread:232715
URL: http://www.dr-bob.org/babble/20030609/msgs/233027.html