Nicotine has a paradoxical effect on
the brain, activating both the reward and aversion circuits. It was previously
thought that it was dopamine that was responsible for the pleasant sensation,
but researchers have just discovered that the dopaminergic neurons are,
conversely, those which cause the initial repulsive effect. On the other hand,
it is she who "traps" the brain to make us dependent.
What do coffee and tobacco have in
common? In both cases, both substances cause an initial aversion when tasted.
The instinctive reaction of disgust towards bitterness thus allowed our
ancestors to avoid poisonous plants. Adults then learn to appreciate the bitter
flavor and end up loving coffee, beer or endives.
For nicotine, it's a bit the same
thing: this substance has a double effect on the brain, activating both
pleasure and aversion. On the one hand, dopamine receptors activate the reward
circuit, on the other, GABA receptors trigger aversion. During the first
experience with tobacco, one or the other wins depending on the people and the
context (stress situation, joint alcohol consumption, etc.).
Ø The craving effect stronger than
aversion
the researchers found that aversion
was activated by dopamine neurons, while GABA neurons send the reward signal. A
result in total contradiction with current theories that dopamine is reserved
for the reward circuit. However, this discovery is not that illogical.
Ø A track to deal with tobacco
addiction?
The need to relieve the negative
effect of the lack of nicotine becomes stronger than the natural repulsion to
nicotine. This discovery, if it could be transposed to humans, could offer new
perspectives for treatment for tobacco addiction. The idea would be for example
to develop a drug reinforcing the aversion to nicotine, a little like
disulfiram (Antabuse) which causes nausea and vomiting when one ingests alcohol
with.
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