"Nicotine appears to repair learning and memory deficits caused by hypothyroidism, although it doesn't appear to improve learning and memory in normal animals," says Al-Zoubi.
The group is now working to uncover the means by which stress and hypothyroidism produce mental deficits and how nicotine corrects these deficits.
Cotinine, the primary breakdown product (metabolite) of nicotine, shows promise for improving memory and for protecting brain cells from diseases such as Alzheimer's and Parkinson's -- but perhaps with less addiction and other side effects of nicotine, report scientists from the Medical College of Georgia. The researchers have also found that, in animal studies, the properties of cotinine may be helpful in treating the debilitating psychotic behavior of people with schizophrenia.
Up to now, cotinine's biggest use has been as a urine marker for tobacco use, although its potential use in curbing smoking also has been explored.
"Many people have thought that cotinine was an essentially inactive metabolite, but we have shown that at appropriate doses, it enhances memory and protects brain cells from dying, as well as having anti-psychotic properties," says Jerry Buccafusco, PhD.
Buccafusco became interested in studying cotinine after observing in studies that monkeys continued to derive memory benefits from nicotine long after the chemical had left the body. Nicotine is rapidly metabolized, and has a half life of about one hour. Cotinine is metabolized at a much lower rate; its half life is about 24 hours.
In one of their current studies, Buccafusco and his colleagues gave both young and old monkeys cotinine, then tested the animals' memory skills. The monkeys that received cotinine did better on the tests than those that didn't receive the metabolite --results similar to those that Buccafusco has found with nicotine.
The researchers also studied cotinine's effect on neuron-
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Contact: Dawn McCoy
dawn@sfn.org
202-462-6688
Society for Neuroscience
11-Nov-2003