Summary: The nicotine dose of a single cigarette blocks the production of estrogen in the brain, causing behavioral changes. The results could shed new light on why quitting smoking may be more difficult for women than for men.
Source: European College of Neuropsychopharmacology
A dose of nicotine equivalent to that contained in a single cigarette blocks the production of estrogen in the brain of women. This may explain several behavioral differences in women who smoke, including why they are more resistant than men to quitting smoking.
This work is presented for the first time at the ECNP Congress in Vienna.
Lead researcher, Associate Professor Erika Comasco (Uppsala University, Sweden) said:
“For the first time, we can see that nicotine works to shut down the estrogen-producing mechanism in the brains of women.
“We were surprised to see that this effect could be observed even with a single dose of nicotine, equivalent to a single cigarette, showing how powerful the effects of tobacco are on a woman’s brain. This is a newly discovered effect, and it is still preliminary work.
“We still don’t know what the behavioral or cognitive outcomes are; only that nicotine acts on this area of the brain, but we note that the affected brain system is a target for addictive drugs, such as nicotine”.
The effect has been demonstrated in the thalamus, which is part of the brain’s limbic system. This system is involved in behavioral and emotional responses.
The researchers, from Uppsala University in Sweden, worked with a group of ten healthy female volunteers.
The women were given a dose of commercially available nicotine intranasally, and at the same time were injected with a radioactive tracer attached to a molecule that binds to the aromatase enzyme: aromatase, also known as estrogen synthase , is the enzyme responsible for the production of estrogen. . MRI and PET brain scans allowed the researchers to visualize both the amount of aromatase and its location in the brain.
The researchers found that a single dose moderately reduced the amount of aromatase in the brain.
It has been known for some time that women and men react differently to nicotine, with women being more resistant to nicotine replacement therapy and showing a greater tendency than men to relapse when trying to quit. to smoke.
However, the biological basis for these differences is not understood. This is the first time that this inhibitory effect on aromatase production has been demonstrated in humans. The effect on men has not been studied.
Professor Comasco continued: “This finding leads us to believe that the effect of nicotine on estrogen production has a significant impact on the brain, but possibly also on other functions, such as the reproductive system – We do not know yet. There are significant differences in how men and women react to smoking.
“Women appear to be more resistant to nicotine replacement therapy, experience more relapses, show greater vulnerability to the heritability of smoking, and are at higher risk of developing primary smoking-related diseases, such as cancer. lung and heart attacks. We now need to understand if this action of nicotine on the hormonal system is involved in one of these reactions.
Of course, this is a relatively small group of women, we need a larger sample to confirm these results. Nevertheless, the message is that nicotine has various effects on the brain, including the production of sex hormones such as estrogen”.
Commenting, Professor Wim van den Brink, Emeritus Professor of Psychiatry and Addiction at the University Medical Center of the University of Amsterdam, said:
“This is indeed an important first discovery. Smoking has many adverse effects in both men and women, but this particular effect of nicotine on reducing estrogen production in women was not known before.
“It should be noted, however, that tobacco addiction is a complex disorder with many contributing factors. It is unlikely that this specific effect of nicotine on the thalamus (and estrogen production) explains all of the observed differences in development, treatment, and outcome between male and female smokers.
“There is still a long way to go from a nicotine-induced reduction in estrogen production to a reduction in the risk of nicotine dependence and negative treatment effects and relapses in female cigarette smokers, but this work deserves further investigation”.
About This Nicotine Research News
Original research: The results were presented at the 35th Congress of the European College of Neuropsychopharmacology (ECNP)