04/03/2019
Tobacco smoking is a major public health problem because it is one of the main avoidable risk factors for the development carcinogenic, cardiovascular and respiratory diseases. According to the WHO, it can also lead to the onset of the mental, physical and behavioural disorders typical of addiction, and epidemiological studies have shown that it predicts the future use of other drugs such as cannabis and cocaine. It has been suggested that electronic cigarettes containing nicotine can diminish the use of conventional cigarettes and the harmful effects of burnt tobacco, but it is still unclear whether this possible benefit extends to all of the effects of tobacco smoking. Researchers at the Italian National Research Council’s Institute of Neurosciences in Milan (Cecilia Gotti and Mariaelvina Sala), in collaboration with their colleagues at the Departments of the Universities of Milan (Milena Moretti, Paola Viani and Francesco Clementi) and Modena-Reggio Emilia (Michele Zoli) and researchers financed by the Zardi-Gori Foundation (Daniela Braida and Luisa Ponzoni, have investigated this in a study whose findings have been published in European Neuropsychopharmacology: ‘Increased sensitivity to Δ9THC-induced rewarding effects after seven weeks’ exposure to electronic and tobacco cigarettes in mice’.
“Tobacco and marijuana are the substances most frequently used by adolescents for recreational purposes,” says Cecilia Gotti of the Institute of Neurosciences, “and the frequency of their use is associated with dependence on nicotine, the principal substance of abuse found in tobacco. The experimental work of the Nobel prize winner Eric Kandel and his wife Denise at the Department of Neuroscience of Columbia University in New York laid the molecular foundations of the hypothesis that nicotine lowers the threshold of dependence on substances such as marijuana and cocaine (the so-called ‘gateway effect’), and our study of validated animal models now shows that exposure to an amount of nicotine contained in tobacco smoke or electronic cigarette vapour that is similar to that absorbed by a smoker over a period of about five years increases the gratifying effects of D9-tetrahydrocannabinol (THC), the active ingredient of marijuana. Even a very low, sub-threshold dose administered to animals that have previously been exposed to tobacco smoke or electronic cigarette vapour leads to a gratifying effect that is not observed in animals exposed to pure air.”
The study also identified a series of molecular cerebral alterations associated with the greater behavioural response to D9-THC of animals previously exposed to nicotine: “For example,” continues Dr. Gotti, “an increased expression of the transcription factor ΔfosB, and an altered expression of glutamate AMPA receptors at the level of nucleus accumbens, an essential intersection in the brain’s pathways of pleasure. Our study confirms that, however it is administered, nicotine becomes a sort of Trojan horse that facilitates the use of cannabis by increasing the gratification it induces; it also suggests some of the possible mechanisms underlying this effect. The risk of becoming dependent on other drugs therefore does not depend on the type of cigarette (conventional or electronic), but on the amount of nicotine they contain. It should also be remembered that this effect is particularly serious if the exposure to nicotine occurs during adolescence, which is a very delicate period for a still-developing brain.”
In terms of health and social policies, these findings suggest the need to consider the question of the danger represented by electronic cigarettes, particularly among adolescents, who are increasingly using them as a means of delivering nicotine, and at an increasingly early age.
Per informazioni:
Cecilia Gotti
Cnr- Istituto di neuroscienze
Via Vanvitelli 32 - 20129 Milano
c.gotti@in.cnr.it
Responsabile Unità Ufficio stampa:
Marco Ferrazzoli
marco.ferrazzoli@cnr.it
ufficiostampa@cnr.it
06 4993 3383
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