We were fascinated a few years ago, when we learned that anti-parkinson’s drugs could, rarely, cause pathological gambling, outrageous appetites, and other risky behaviors.
Granted, we knew that these drugs (specifically the newer Pramipexole) were dopamine agonists, and that dopamine is involved in the pleasure and reward circuits in the brain, but everything gets a little hazy after that.
A new report out of Pittsburgh sheds light on this rare side effect. A research team led by Dr. Anthony Grace found the site in the brain that acts as a gateway for dopamine neuron bursts, which signal reward and goal-directed activity.
Using anesthetized rats, Lodge and Grace found that one area in the brain stem, known as the laterodorsal tegmental nucleus, is critical to normal dopamine function.
“We’ve found, for the first time, the brain area that acts as the gate, telling neurons either to go into this communication mode or to stop communicating,” says Grace. “All the other parts of the brain that talk to the dopamine neurons can only do it when this area puts them into the communication mode.”
As a result, disruption in that area may play a major role in dopamine-related brain function, both in normal behaviors and psychiatric disorders.
The brain area identified by the Pitt researchers is regulated by the “planning” part of the brain, the prefrontal cortex (PFC), thereby providing a powerful indirect means for the PFC to affect the activity of dopamine neurons. Such a link could explain how changes in the PFC, seen in disorders like schizophrenia and drug addiction, disrupt the signaling of dopamine neurons.
It’s neat to see psychiatry and neuroscience coming together like this.
More from Grace and Lodge’s PNAS abstract…