Nicotine acts on the symptoms of schizophrenia, according to French researchers. This discovery opens up a potential therapeutic avenue
Between 80 and 90% of schizophrenic patients are smokers. Several studies, including one published in 2016 in the journal Schizophrenia Reasearch, show a strong link between smoking and illness. Smoking seems to be a kind of self-medication, a way to compensate for the deficits caused by their illness. Nicotine would act directly on their symptoms, believe French researchers from the Pasteur Institute, CNRS, Inserm and ENS.
In an article published in Nature Medicine, they succeeded, thanks to an animal model, to propose an explanation on the mechanism of action of nicotine in the patients.
They used a gene known to be associated with both cognitive impairment in schizophrenics and tobacco addiction, CHRNA5, which is present in 37% of Europeans. By integrating it into the genome of mice, they managed to reproduce these disorders in animals. Then, by observing their brain activity with or without chronic nicotine intake, the researchers were able to propose an explanation: nicotine stimulates deficient areas of the brain in schizophrenic patients.
The pyramidal cells refitted
Schizophrenia results in an alteration of certain neurons in the prefrontal cortex, a region of the brain located just above the eyes, and associated with cognition, decision-making and working memory. The activity of these neurons, called pyramidal cells, is weakened.
Nicotine would act, according to the results of the French team, on interneurons, small brain cells that establish connections in the brain. It takes the place of a neurotransmitter on these interneurons. Like spare keys to open a multitude of locks, a chronic supply of nicotine stimulates them and, in turn, the pyramidal cells regain normal activity.
Find a key without side effects
Schizophrenics therefore smoke so that nicotine stimulates their neurons. “There is no question of saying that tobacco, even for schizophrenics, can be good for health, explains to Why actor Fani Koukouli, neurobiologist at the Institut Pasteur, and lead author of the study. Tobacco, and nicotine itself, have harmful effects. But what we can imagine as a therapeutic avenue is to find a nicotinic receptor agonist; a molecule which acts on the same receptors, and which would allow the pyramidal cells to regain a state of normal excitation. “
This molecule should be freed from the addictive effect of nicotine, as well as its effects on cellular aging, or on cardiovascular activity.
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