Clear The Air News Tobacco Blog Rotating Header Image

March 2nd, 2009:

Why Nicotine Prefers Brains Over Brawn

By Haley Stephenson – ScienceNOW Daily News – 2 March 2009

If nicotine liked muscle receptors as much as it likes brain receptors, a single cigarette would kill. Scientists have finally figured out why the molecule is so picky–a finding that may shed light on the addictiveness of smoking.

For nicotine–or any molecule–to interact with its receptor, the two must bind. Having opposite charges on the molecule and the receptor’s binding site, referred to as the “box,” helps. But the nicotine receptors in the brain and muscles are nearly identical–nicotine has a positive charge, and both receptors’ boxes have a negative charge. So something else must explain why the brain loves nicotine whereas muscles shun it.

Nicotine (center) nestled into brain receptor "box."

Nicotine (center) nestled into brain receptor "box."

After more than a decade of work, Dennis Dougherty, a chemist at the California Institute of Technology in Pasadena, and his colleagues finally have the answer. It turns out that a single amino acid makes all the difference. Near the box region, the brain receptor has a lysine molecule, whereas the muscle receptor has a glycine molecule. What the lysine does, Dougherty and colleagues report online this week in Nature, is change the shape of the brain receptor’s box, effectively making its negative charge more accessible to nicotine–a situation known as a cation-pi interaction. “The box reshapes so nicotine can cozy up,” Dougherty says.

For its part, the box in the muscle receptor is ideally configured for a molecule known as acetylcholine, which helps muscles contract. When Dougherty’s team switched out the muscle receptor’s glycine for a lysine, the muscle embraced nicotine as if it were acetylcholine. It’s a good thing that doesn’t happen in the body, says Mark Levandoski, a chemist at Grinnell College in Iowa, who was not part of the study. Smoking would immediately trigger abnormal contractions that would paralyze muscles, like those involved in breathing. “If nicotine were lighting up our muscles the way acetylcholine does, we’d be in big trouble,” Levandoski says.

Scientists can only speculate about why the brain and muscle receptors differ so much. For now, Dougherty and his lab want to determine whether the binding between other nicotine-family receptors and pharmaceutical drugs also involves cation-pi interactions. Studying the binding interactions within the nicotine receptor family might lead not only to new ways of helping people stop smoking, he says, but also to new treatments for illnesses such as Alzheimer’s disease, autism, Parkinson’s disease, and schizophrenia.

Punitive Tactics Just Put Smokers On The Defensive

Mar 02, 2009 – SCMP

The expected benefits of the 50 per cent rise in tobacco duty seem, at first sight, quite laudable – a reduction in cigarette smoking by young smokers unable to afford this debilitating habit.

Given such a draconian tactic and one that will affect a significant percentage of the community, is it not time that we reviewed the success of the anti-smoking tactics? Just what has been the success of all the initiatives that the anti-smoking lobby has had implemented over the last two decades in Hong Kong?

This lobby has been given everything it asked for. We have had advertising and promotion bans, smoking restrictions, community anti-smoking messages, on-premises smoking restrictions and cigarette pack warnings. But what have been the social benefits of all these policies? Unfortunately, there have been no benefits. The incidence of cigarette smoking in Hong Kong and many countries with similar restrictions continues to rise.

The only rationale is that these strategies have never worked, nor were they ever going to, because they do not properly address smokers’ motivations and the habit issue. Punitive approaches such as restrictions, bans and taxes clearly do not work. They just put smokers on the defensive. It can even make smoking attractive to some young people because it appears to be rebellious, and so they take up the habit.

Introducing penalties in the form of taxation to force down habit-formed consumption never works, as anyone who has been in the alcohol and cigarette industry knows.

It always leads to smuggling and tax avoidance. Criminal elements become involved, hell-bent on the monetary advantage untaxed cigarettes will offer.

This is a lesson that was learned in the 1930s during Prohibition in the US. Have we not progressed since then? Those who would quote examples of declines in cigarette consumption following tax hikes, make the mistake of relying on and quoting official figures for cigarette imports and production. These are obviously grossly inaccurate because there is no way to collect accurate figures regarding the volume of smuggling. Smuggling activities will increase dramatically as a result.

We need new and better policies to address this health issue in Hong Kong.

We must have more enlightened public-health thinkers who can see beyond punitive measures.

Is it not time to ask the anti-smoking lobby to set some performance goals and be accountable when policies fail, as will be the case with this most recent government tax initiative?

Chris Robinson, Pok Fu Lam

A Victory For Public Health

Mar 02, 2009 – SCMP

While much of the government’s attention is understandably taken up with the complexities of the global financial crisis it is to be congratulated for not ignoring the public’s health in Wednesday’s budget.

The increase of 50 per cent in tobacco tax is a very welcome and long overdue step. We know from international evidence that this tax increase will decrease the misery of smoking-related diseases not only among smokers, but also those exposed to their second-hand smoke, particularly children.

Coupled with a commitment to strengthening support for those who wish to stop smoking, this is a major step forward for public health in Hong Kong.

The additional resources to develop primary care, especially in poorly served geographical areas, and to implement programmes, such as pneumococcal vaccination for children, are also welcome as is the continued support for moving forward on e-health records.

These initiatives provide the opportunity to focus more on prevention and community-based care, moving forward on the health-care-reform commitments to improve primary care.

These must be steps in the right direction.

Sian Griffiths, director, school of public health, Chinese University of Hong Kong

The Anatomy of Addiction

(ABC 6 NEWS) – Cigarettes are highly addicting.

But why is it that some people who try cigarettes can put them down and never get addicted while others get hooked right away?

Doctors at Mayo Clinic say the answer lies in how your brain responds to nicotine.

A few puffs is all it takes for some people to become addicted to cigarettes.

And then there are people like Uncle Charlie.

“Everyone knows an Uncle Charlie,” says Dr. Richard Hunt. “Uncle Charlie was basically not a very productive person. He couldn’t hold a job, was married six times, smoked a pack of cigarettes a day for 25 years, and one day decided to stop smoking and he did. He didn’t have withdrawal symptoms, didn’t use any medications. So for the addicted smoker, they look at Uncle Charlie and say, if he could do that and I can’t there must be something wrong with me. And the reality is, there’s not something wrong with the person, it’s that their brain has been altered because of smoking cigarettes.”

Dr. Hurt heads the center for tobacco free living.

He says your chances of becoming addicted to cigarettes hinge on genetics, on how your brain responds to nicotine.

It only takes about five heartbeats for nicotine to go from the cigarette to your brain.

For many people it stimulates receptors that release dopamine and cause the pleasure response.

Over time, the receptors increase in number and change the anatomy of the brain.

So when you try to quit smoking you cut off the pleasure response because you are depriving the receptors of nicotine.

“And they object to that with withdrawal symptoms,” says Dr. Hunt.

Those symptoms include irritability, anxiety and the inability to concentrate.

If you make it through withdrawal and quit smoking, the number of nicotine receptors reduces to normal.

“But they don’t forget what all that felt like. So a smoker may have stopped smoking for six months and then be in a situation where they normally would smoke again, and the receptors say, ‘you know, it used to be when I was in that situation I’d have a cigarette, so I want a cigarette right this minute,” explains Dr. Hunt.

Such urges can last for years after quitting.

But Dr. Hurt says medications such as the nicotine patch or other non-nicotine prescription medications plus counseling can help smokers gain control over their addiction and move forward into a healthier, smoke-free life.