New research discovers link between [tobacco] smoking and brain damage

June 23rd, 2009 in Medicine & Health / Neuroscience

New research which suggests a direct link between smoking and brain damage will
be published in the July issue of the Journal of Neurochemistry. Researchers, led by
Debapriya Ghosh and Dr Anirban Basu from the Indian National Brain Research
Center (NBRC), have found that a compound in tobacco provokes white blood cells in
the central nervous system to attack healthy cells, leading to severe neurological
damage.

The research centers on a compound known as NNK, which is common in tobacco.
NNK is a procarinogen, a chemical substance which becomes carcinogenic when it is
altered by the metabolic process of the body.

Unlike alcohol or drug abuse NNK does not appear to harm brain cells directly,
however, the research team believe it may cause neuroinflamation, a condition which
leads to disorders such as Multiple Sclerosis.

"Considering the extreme economical and disease burden of neuroinflammation
related disorders, it is extremely important from a medical, social and economic point
of view to discover if NNK in tobacco causes neuroinflammation" said Ghosh.

To prove if such a link exists the team conducted two types of tests, one outside of a
living host in glass and one in laboratory mice. The team used blot analysis
techniques which showed that the introduction of NNK resulted in a clear increase in
proinflammatory signaling proteins, proinflammatory effector proteins and other
stress related proteins. Increased levels of proinflammatory cytokines, which act as
molecular messengers between cells, were also detected.

This shows that NNK provokes an exaggerated response from the brain's immune
cells, known as microglia. Microglia cells act as 'destroyers' for the brain by attacking
damaged or unhealthy cells. However, when provoked by NNK these cells start to
attack healthy brain cells rather than the unhealthy cells they are supposed to attack.

"Our findings prove that tobacco compound NNK can activate microglia significantly
which subsequently harms the nerve cells," said Basu.

While other harmful side effects of smoking, such as lung disease, usually derive from
tar or smoke this research suggests damage is not confined only to smoking. NNK is
present in all forms of tobacco and therefore it can also enter the body through
chewing.

The study also suggests that second hand smoking may lead to the same
neuroinflamation conditions. Concentrations of NNK in tobacco can vary from 20-310
nanograms in cigarettes. However, NNK is also present in the smoke itself, smoke-
filled air indoors may contain up to 26 nanograms of NNK. This means that both
direct and second-hand smoking can lead to substantial measures of NNK intake.

"This research sheds light on the processes that lead to nerve cell damage in those
who smoke cigarettes or consume tobacco products on regular basis," said Ghosh.

Source: Wiley (news : web)
http://www.physorg.com/news164962655.html