As part of a study carried out by a group of scientists from China and the USA, and headed by Inés Ibáñez-Tallon -of the Rockefeller University of New York-, an experiment was carried out with mice that were subjected to a treatment of six weeks.
During that time the animals were fed with water containing nicotine, in order to discover which cells respond to that stimulant. It is known that nicotine influences brain receptors that, in turn, release the well-known “happiness hormones”, including dopamine.
The interest of the scientists was mainly focused on two parts of the midbrain: the habenula and the interpeduncular nucleus. The experiment showed that it was the second of these two parts (the interpeduncular nucleus) that underwent changes after the continuous consumption of nicotine, and in which neurons whose functions were affected were found. These cells were called Amigo1 and, according to the researchers, affect the two mentioned areas of the brain , causing addiction.
Generally, the interaction of the habenula and the interpeduncular nucleus causes a smaller amount of “pleasure” to be released, which protects against addiction, but the permanent stimulation of the Amigo1 cells blocks this effect.
According to the report, published by the Proceedings of the National Academy of Sciences of the United States of America (PNAS), the results show that the mice acquired an addiction . To corroborate this, in the second part of the experiment the rodents were given the opportunity to choose between two spaces, one that had water with nicotine and another that did not: they preferred to stay in the first, to receive a new dose of drug.
The effects of Amigo1 cells were proven in later experiments: when these effects were diminished in animals by means of genetic engineering, the mice recovered from the addiction.
Scientists believe that with humans the situation is similar: the more the brain is stimulated, the greater the destruction of defense mechanisms. According to the authors, this finding is only a step forward in the study of the effects that nicotine produces on brain cells, and they hope that one day personalized therapy methods will be developed that are available to everyone.