Alcohol dependence is one of the most common neuropsychiatric diseases. In Germany, more than five million people are affected. The consequences are often severe physical and mental suffering and a high mortality rate. The average life expectancy of those affected is reduced by more than 22 years. Despite the severity of the disease, whose chronic course is characterized by frequently recurring relapses into excessive alcohol consumption and great suffering pressure for those affected, we still know little about the causal mechanisms in the brain.
Cortical mGluR2 deficit as a pathological molecular mechanism of altered behavior in addiction
Mental processes that control behavior, attention and emotions are known as executive functions. In many psychiatric diseases, the ability to control one’s own thoughts and actions and to regulate emotions are disturbed, for example in attention deficit hyperactivity disorder (ADHD), autism, schizophrenia, borderline syndrome and also in addiction.
In a multidisciplinary, international collaboration led by Dr. Marcus Meinhardt, Prof. Dr. Rainer Spanagel and Prof. Dr. Wolfgang Sommer (all at the Central Institute of Mental Health in Mannheim), the molecular mechanism of altered executive functions and increased relapses in alcohol dependence have been investigated. The research focuses on the role of the metabotropic glutamate receptor 2 (mGluR2). In the brain, this receptor works as an antenna for the neurotransmitter-glutamate and regulates its release in various brain areas. In their current work, which has now been published in the journal Science Advances, the research team shows a causal link between a reduced mGluR2 function within the brain region of the prefrontal cortex in alcohol-dependent rodents and an impaired executive control as well as craving for alcohol. mGluR2 activation has thus been identified as a potential therapeutic mechanism in alcohol dependence.
Psilocybin restores the production of mGluR2
Hallucinogenic substances such as psilocybin – the active ingredient in the so-called magic mushrooms – or LSD act on serotonin 2A receptors (5-HT2AR) in the brain. These receptors are present in large numbers in the prefrontal cortex. Previous research has shown that 5-HT2AR and mGluR2 can form a functional complex. This complex has been linked to the mechanism of action of psychedelics, but the molecular functions of this complex in addiction were previously unknown. “We were able to show that psilocybin can restore mGluR2 levels which leads to a reduction in relapses to alcohol”, says Marcus Meinhardt. Thus, this research opens up the possibility of developing new therapeutic approaches that focus on psilocybin as a driver of mGluR2.