Researchers have successfully tested a potential new tobacco treatment in rats: a modified enzyme called NicA2-J1, which is said to have the power to break down nicotine in the blood before it reaches the brain.
Have researchers finally discovered a vaccine against cigarette addiction? This is what a new study, published on October 17 in Science Advancesand in which American scientists from the Scripps Research Institute claim to have discovered an enzyme capable of destroying nicotine in the blood before it reaches the brain.
Treatment for addiction and withdrawal symptoms
The scientists tested the modified enzyme on nicotine-dependent rats. Called NicA2-J1, it is a modified version of a natural enzyme produced by the bacteria Pseudomonas putida. These modifications were intended to make the enzyme more potent and to optimize its residence time in the blood.
In a series of experiments, lab rats spent 21 hours a day, for 12 days, in a chamber where they could press a lever to give themselves an intravenous infusion of nicotine. In this way, they learned to self-administer nicotine and became addicted to it. After 12 days, they only had access to nicotine every 48 hours, leading them to experience withdrawal symptoms between bouts of access. It also led them to increase their nicotine intake whenever they had access to it.
The researchers then proceeded to treat the dependent rats with a high dose of NicA2-J1 (10 mg/Kg). They then realized that these rodents continued to self-administer nicotine when they could, but had very low blood levels of nicotine compared to control rats who had not received the enzyme. In fact, signs of nicotine withdrawal such as pain sensitivity and aggressive behavior were reduced during withdrawal periods compared to untreated rats.
For the researchers, this discovery which consists in reversing the addiction to nicotine is very promising “because it allows to reduce the addiction to nicotine without causing cravings and other severe withdrawal symptoms”. “It works in the blood, not in the brain. Its side effects should therefore be minimal,” says Olivier George, associate professor at the Scripps Research Institute and lead author of the study.
Nicotine, responsible for tobacco addiction
Above all, this new work is a major step forward, as it is the first time that this approach to reversing nicotine addiction has shown such advanced results. Previous treatments had been developed, but they did not sufficiently reduce nicotine blood levels to be effective.
It is this addiction to nicotine that pushes smokers to continue to use tobacco, despite their desire to quit. Researchers estimate that about 60% of people who try cigarettes become daily smokers, and about 75% of daily smokers relapse after a period of withdrawal. The fault therefore, with nicotine, a psychoactive substance which acts on the brain by binding to the nicotinic receptors of neurons and the modification of neurotransmitters. These then produce dopamine, a hormone that gives a feeling of well-being and satisfaction. The more you smoke, the more the brain gets used to the presence of nicotine, and the more the receptors are sensitive.
If it proves effective on humans, the modified NicA2-J1 enzyme will therefore make it possible to destroy nicotine before it binds to the receptors in the brain. Which could make the addiction go away. For now, clinical trials on humans have not yet been launched, explain the researchers, who are looking for volunteers.
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