Passage 1 Nicotine's fatal Attraction The nicotine in a single cigarette can trigger a long-lasting chemical change in scientists have discovered. If they can confirm that similar changes occur in living brains, it might leas to new treatments for nicotine addiction Rats exposed to nicotine have raised levels of the neurotransmitter dopamine in their brains. Dopamine is responsible for feelings of pleasure, and high levels of the chemical last for hours after exposure to nicotine. Scientists suspected that this leads to addiction Now neurobiologists niel McGehee and hulbert Mansvelder from the University of Chicago have uncovered how nicotine has this insidious effect. Working on slices of rat brain, the team discovered that nicotine attaches to alpha7, a specific sub-unit of a family release glutamate. This in turn persuades other neurons to release dopamine. Levels of this key neurotransmitter persist for 45 minutes or more after nicotine exposur They say the buzz is higher the next time the same part of the brain is exposed to nicotine. The effect, called long-term potentiation, is also linked to memory and learning in a part of the brain called the hippocampus. " It's an insidious process that is motivating us to breathe carcinogens into our lungs, says McGehee. The team has calculated that the nicotine from just one cigarette is enough for the brain to remember the"high that results The addictive effect of nicotine explains why so many people cannot stop smoking, despite widespread awareness that it causes heart disease and cancer. Experts estimate that one in two smokers will die prematurely as a direct result of their habit he new finding runs counter to the traditional theory that addiction comes when repeated exposure to a chemical weakens its effect, so that a person needs to take more and more of the drug to get a hit". but the results are consistent with a newer theory of addiction, according to lan Stolerman of the Institute of Psychiatry at Kings College, London. This theory says that repeated exposure increases the users sensitivity to a drug. And this is what makes the experience more and pleasurable- and therefore harder to give up Now the researchers need to reproduce the results in live animals, Stolerman says. Earlier studies in animals failed to show that blocking alpha7 receptors affects nicotine dependence If it can be verified that alpha7 receptors play a role in tobacco addiction it opens up possibilities of new drugs that may help people to stop smoking, says Stolerman. The drugs most often used today to block nicotine have marked effects outside the brain. They cause low blood pressure, dizziness and blurred vision, adds Stolerman He suggests that new drugs might avoid such problems. Since aloha receptorsPassage 1 Nicotine’s Fatal Attraction The nicotine in a single cigarette can trigger a long-lasting chemical change in brain cells, scientists have discovered. If they can confirm that similar changes occur in living brains, it might leas to new treatments for nicotine addiction. Rats exposed to nicotine have raised levels of the neurotransmitter dopamine in their brains. Dopamine is responsible for feelings of pleasure, and high levels of the chemical last for hours after exposure to nicotine. Scientists suspected that this leads to addiction. Now neurobiologists Daniel McGehee and Hulbert Mansvelder from the University of Chicago have uncovered how nicotine has this insidious effect. Working on slices of rat brain, the team discovered that nicotine attaches to alpha7, a specific sub-unit of a family of nicotinic receptors in neurons. As a result, these neurons release glutamate. This in turn persuades other neurons to release dopamine. Levels of this key neurotransmitter persist for 45 minutes or more after nicotine exposure. They say the buzz is higher the next time the same part of the brain is exposed to nicotine. The effect, called long-term potentiation, is also linked to memory and learning in a part of the brain called the hippocampus. “It’s an insidious process that is motivating us to breathe carcinogens into our lungs,” says McGehee. The team has calculated that the nicotine from just one cigarette is enough for the brain to remember the “high” that results. The addictive effect of nicotine explains why so many people cannot stop smoking, despite widespread awareness that it causes heart disease and cancer. Experts estimate that one in two smokers will die prematurely as a direct result of their habit. The new finding runs counter to the traditional theory that addiction comes when repeated exposure to a chemical weakens its effect, so that a person needs to take more and more of the drug to get a “hit”. But the results are consistent with a newer theory of addiction, according to Ian Stolerman of the Institute of Psychiatry at King’s College, London. This theory says that repeated exposure increases the user’s sensitivity to a drug. And this is what makes the experience more and more pleasurable – and therefore harder to give up. Now the researchers need to reproduce the results in live animals, Stolerman says. Earlier studies in animals failed to show that blocking alpha7 receptors affects nicotine dependence. “If it can be verified that alpha7 receptors play a role in tobacco addiction it opens up possibilities of new drugs that may help people to stop smoking,” says Stolerman. The drugs most often used today to block nicotine have marked effects outside the brain. They cause low blood pressure, dizziness and blurred vision, adds Stolerman. He suggests that new drugs might avoid such problems. “Since aloha7 receptors