Magazine article Science News

Clues to Nicotine's Memory, Plaque Impact

Magazine article Science News

Clues to Nicotine's Memory, Plaque Impact

Article excerpt

Low concentrations of nicotine in the blood tend to boost volunteers' performance on tasks that require them to retain and interpret recently acquired information. This memory assist may stem from nicotine's ability to enhance the transmission of chemical messengers in a brain structure known as the hippocampus, according to a new report.

Unrelated, preliminary findings suggest that nicotine may also slow plaque formation in the brains of people with Alzheimer's disease.

Nicotine activates a class of receptors on hippocampal cells that typically responds to the neurotransmitter acetylcholine, explains neuroscientist Richard Gray of Baylor College of Medicine in Houston. Like naturally occurring acetylcholine, externally administered nicotine induces these so-called nicotinic acetylcholine receptors to bolster the actions of other neurotransmitters that facilitate memory, Gray and his colleagues assert.

Alzheimer's disease may derive, at least in part, from an inactivation of these hippocampal sites, known as alpha 7-type receptors, Gray's team theorizes in the Oct. 24 NATURE.

The new findings serve as "an important step toward [recognizing] nicotine as a powerful modulator of memory," state neuroscientists Daniel S. McGehee of the University of Chicago and Lorna W. Role of Columbia University in an accompanying commentary.

Nonetheless, the activation of nicotinic acetylcholine receptors represents only one of many still poorly understood steps that underlie nicotine's effects on thinking and behavior, McGehee and Role contend. Controversial research has indicated that although low concentrations of nicotine aid performance on relatively simple memory tasks, high concentrations interfere with complex mental operations

Gray's group first established that low concentrations of nicotine, comparable to those observed in the bloodstream after a smoker has consumed a single cigarette, enhance the rate of nerve-impulse transmission in rat hippocampal cells preserved in the lab. …

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