"The depth of a person's addiction to nicotine appears to depend on his or her unique internal chemistry and genetic make-up," said lead author Jerry Stitzel, an assistant professor in CU-Boulder's department of integrative physiology and researcher with CU-Boulder's Institute for Behavioral Genetics.
Stitzel presented his team's findings in San Diego on Monday at Neuroscience 2007, an annual scientific meeting that is taking place through Wednesday.
He and his team set out to evaluate the effects of nicotine over the course of a day by examining mice that could make and "recognize" melatonin, a powerful hormone and antioxidant, and others that could not. Scientists believe that melatonin, which is produced by darkness, tells our bodies when to sleep.
The CU researchers found that the reduced effects of nicotine at night were dependent on the mice's genetic make-up and whether their brains and bodies were able to recognize melatonin. They also found that the daytime effects of nicotine were greatest when levels of the stress hormone corticosterone were high.
The second finding could explain why many smokers report that the first cigarette of the day is the most satisfying. Cortisol, the human equivalent of corticosterone, is at peak levels in the early morning, Stitzel said.
"The negative health consequences of smoking have become well known, and a large majority of smokers say that they would like to quit," Stitzel said. "As such, we need to understand the interaction between smoking, genes and internal chemistry so we can target new therapies to those who have a hard time quitting."
While the team's research could shed light on why people smoke and how nicotine affects them, Stitzel says more research is needed to determine the role that melatonin plays in altering the effects of nicotine, and whether the correlation between higher corticosterone levels and nicotine sensitivity is a coincidence.
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McDonald supports her diet with scientific research and decades of advanced specialty training in areas including women's health, family practice, nutrition, exercise sports medicine and heart disease prevention. A leading integrative medicine practitioner with a practice in Danville, CA, McDonald is a faculty member with the Nutrition and Health Conference -- State of the Science and Clinical Application and a graduate of the University of Arizona's Program of Integrative Medicine.
A simple blood test determines your Apo E genotype; for those not interested in knowing their genotype, Pamela McDonald provides dietary information that benefits the gene, plus suggestions for a gene supportive environment including appropriate exercise, physical environments, mental and emotional experiences, and spiritual beliefs.
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