Boston Globe on 7/18/96:

Authors say new study confirms nicotine's addictive properties

Adding further evidence for the addicting power of tobacco, a new study reveals that nicotine targets the same "reward system" in the brain as cocaine, amphetamines and morphine, and that it stimulates the brain in the same way those drugs do.

Like those addicting drugs, nicotine speeds up activity in a part of the brain that harbors nerves influencing emotions and motivation, the scientists said.

It also triggers the brain's release of a chemical messenger, dopamine, which has been been linked to the addicting effects of other drugs.

Published as a letter in today's issue of the journal Science, the report from Italian researchers strengthened the conclusion of most addiction specialists about nicotine's similarity to other drugs that incite compulsive use and abuse.

By chance, the report comes as GOP presidential candidate Bob Dole has become entangled in a debate about nicotine's status as an adductive drug. "You know, there is a mixed view among scientists and doctors whether it's addictive or not," Dole told NBC's Katie Couric in an interview earlier this month. "I'm not certain it's addictive."

Alan Leshner, director of the National Institute on Drug Abuse, declined to comment on Dole's assertions, but in an interview said of the new report: "In the scientific community there is fundamentally no question about nicotine's being addicting. this study reinforces the commonality between nicotine's physiological effects and those of other addicting substances."

The US Surgeon General declared nicotine an addicting drug in 1988.

The Italian researchers, headed by Gaetano Di Chiara at the University of Cagliari, previously had reported that nicotine injected into rats targets a structure in the brain called the nucleus accumbens. "Most if not all drugs abused by humans stimulate dopamine transmission in the nucleus accumbens," the scientists wrote in the letter Nature.

The newest research goes further. The scientists implanted tine, hair-like electrodes in the brains of rats to more precisely track the action of nicotine. They demonstrated that nicotine spurred the secretion of dopamine in a specific part of the nucleus accumbens, known as the shell, and also caused specific cells in the shell to use more energy.

These findings, the researchers said, show that nicotine shares with other addictive drugs this very specific activity in the brain - activity that scientists believe is critical to the drugs' addictive power. In fact, when scientists deliberately damage nerves in that tine structure, rats that had been trained to self-administer nicotine stop giving themselves the drug.

Leslie L. Iversen, a pharmacologist at the University of Oxford in England, wrote in an accompanying article that the Italian research "adds new weight to the conclusion that nicotine is indeed addictive."

NEWSDAY
article [11/27/97]:

AH, THAT FIRST PUFF / STUDY TELLS WHY SMOKERS NEED MORE AND MORE

Most cigarette smokers will tell you that the first puff in the morning is the best of the day. Now a Texas researcher has found the reason why, a kind of biological bait-and-switch scam.

Nicotine uses the same part of the brain that puts the pleasure in sex or eating, the midbrain dopamine neurons. But smoking fools the brain into growing extra nicotine receptors on those neurons so that a person will want more and more, said Dr. John A. Dain of the Baylor College of Medicine, Houston.

"That first one in the morning gets those receptors very excited, they become very active and it gives the smoker great pleasure," Dain said.

But then nicotine pulls a double cross.

"On every other smoke the nicotine makes the receptors less and less sensitive, so that the smoking gets to be less and less enjoyable," said Dain, who published his findings in this week's issue of the journal Nature.

He said after three or four cigarettes, a smoker will be twitching to have another, not because it is a pleasure but because the body needs more and more nicotine to activate enough dopamine receptors to give even a little pleasure.

"You want to do it again, but as the day wears on and the smoker smokes more, the nicotine remains in the body and brain. The receptors begin to turn off," Dain said.

Dain said the body needs eight hours of sleep to let the nicotine level drop so that the first-cigarette experience can be repeated.

"A person trying to quit has to get out of bed without that cigarette, and we have been getting a lot of anecdotal material telling us that people just can't," Dain said.

Dain's anecdotes have scientific backing from others.

"One of the ways we gauge nicotine addiction is by how long a person can last before lighting that first cigarette," Hamer said. "We have found some people who are still under the covers when they light up."

Hamer said that smokers are actually going through withdrawal while they are sleeping and have a hard time passing up the first smoke of the morning.

"We have the same failure rate for heroin addiction as for people who try to kick the cigarette habit - fewer than 20 percent stay off after the first year," Hamer said.

Dain said if a person can last for a week or more without a cigarette, he or she can probably kick the habit and that in a month or two the extra nicotine receptors in the brain will disappear. With the extra neurons goes the craving for a smoke. He cautioned, however, that memory of the pleasure sparked by second- hand smoke can seduce a person back to tobacco.