02 Nov Heroin Fires Off Reward-Seeking Neurons In Less Than a Minute
MedicalResearch.com Interview with:
Michaël Loureiro, PhD
Research Assistant – Group Lüscher
Dpt. of Fundamental Neuroscience
University of Geneva – Faculty of Medicine
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Addiction refers to the repeated and irrepressible urge to consume a drug even in the light of negative consequences.
All addictive drugs are initially rewarding and have powerful reinforcing properties, which drive users to use the drug again and again. Within the scientific community, it has been repeatedly argued that for opioids, this initial reinforcing effect does not involve dopamine, and no consensus was emerging.
In our study we used some of the most advanced genetic tools to observe that in less than a minute heroin strongly increased the activity of neurons in the midbrain causing a release of dopamine in the striatum, a brain region essential for reward seeking. We further used neuroanatomical tracing methods and found that dopamine neurons activated by heroin were projecting to the very medial region of the ventral striatum.
Finally, when we silenced dopamine neurons, heroin lost its reinforcing power, confirming the validity of the dopamine activation hypothesis for opioids.
MedicalResearch.com: What should readers take away from your report?
Response: While opioids are very helpful when used as painkillers, the dark side is their addictive properties, which we now know starts with their ability to engage dopamine neurons in the midbrain.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Future studies designed to understand opioid addiction should definitely take into account the early engagement of the dopamine system. However, beyond our results, many questions remains open. For example, how does this initial recruitment of the dopamine system triggers the next steps, eventually responsible for long lasting neuronal adaptations driving compulsive consumption despite negative consequences for their health and social life? Is it possible to design analgesic opioid-like compounds, however without recruiting dopamine neurons?
Dopamine neurons projecting to medial shell of the nucleus accumbens drive heroin reinforcement
Julie Corre,Ruud van Zessen,Michaël Loureiro,Tommaso Patriarchi,Lin Tian,Vincent Pascoli,Christian Lüscher
eLife 2018;7:e39945 DOI: 10.7554/eLife.39945
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