Swiss scientists recently discovered that taking fentanyl triggers two distinct areas of the brain, which could explain the particularly addictive nature of this substance.
- Fentanyl is an opiate, which was developed to relieve pain in cancer patients. Its use has since been largely diverted.
- In the United States, fentanyl addiction causes three-quarters of overdose deaths.
- Swiss researchers recently suggested that taking fentanyl could activate two distinct regions of the brain, which would explain the addictive power of this opiate.
Originally developed for cancer patients, fentanyl is a synthetic opiate that has been diverted from its original medical use. In the United States, it is responsible for three-quarters of overdose deaths. It causes an intense euphoric effect then significant withdrawal symptoms (tremors, excessive sweating, pain, etc.) a few hours after the last dose.
A path to understanding the impact of opioid addiction
The effects of fentanyl on the brain are still poorly understood. Researchers at the University of Geneva (UNIGE) recently observed that this powerful painkiller triggers two distinct populations of cells in the brain. “This would explain why people take the drug not only for its euphoric effect, but also to avoid withdrawal, and why opioids are more addictive than other drugs.”we can read in a press release from UNIGE. This work was the subject of a publication in the journal Nature.
Administered intravenously, fentanyl causes activation of dopaminergic neurons, responsible for the release of dopamine, a hormone that contributes to the feeling of euphoria. These cells are normally under the control of GABA inhibitory neurons, but opiates are able to block their action and thus increase the activity of dopaminergic neurons, triggering the euphoric phase. The key to understanding is the “mu” opiate receptor. “We are talking about positive reinforcement when the pleasant sensation leads to the repetition of taking the product, and negative reinforcement when the drug is consumed to avoid withdrawal syndrome”indicated Christian Lüscher, responsible for this work and professor in the department of fundamental neuroscience of the Faculty of Medicine of UNIGE and at the Synapsy Center for research in neuroscience for mental health.
Fentanyl: the intense discomfort linked to withdrawal takes place in another region of the brain
As the scientists explained, the euphoric effect takes place in the mesolimbic system, but they found that withdrawal symptoms take place in another brain region. They then discovered a population of cells, which were until now unknown, located in the central amygdala, a system which regulates our actions in the face of fear. “Until now, we thought that the mechanisms of positive reinforcement as well as negative reinforcement took place in the same brain area, the mesolimbic system. However, our hypothesis suggests that the origin of negative reinforcement is to be found in cells which express mu receptor elsewhere in the brain”described Fabrice Chaudun, first author of the study and assistant professor in the laboratory of Christian Lüscher.
According to those responsible for this research, their conclusions “radically change the model of understanding opioid addiction.” The fact that positive and negative reinforcement pass through two different networks could explain why opiates have a particularly high addictive nature and encourage irrational consumption. These initial results could also be an avenue of research for the development of painkillers without the risk of addiction.
