The key to understanding the nature of addiction lies in the brains of rats. In a study recently published in the Proceedings of the National Academy of Sciences of the United States of America, lead author Shelly Flagel, Ph.D., and a team of researchers conducted a study on the genetic factors of addiction.
“We’ve been selectively breeding rats based on locomotor response to novelty for several generations,” Flagel said. “The reason we’ve been doing so is because their traits have previously been associated with addiction-related behaviors.”
During the experiment, researchers specifically bred two kinds of rats: bred high-responders (bHRs) that tend to explore their surroundings and bred low-responders (bLRs) that respond anxiously in new situations.
Researchers then examined the rats’ genetic code in search of D2, a natural ‘pleasure receptor.’ While examining both groups, they found that bHR rats had lower levels of D2 instructions encoded in their genes compared to bLRs. This receptor plays an important role in addiction because it allows the brain to receive the chemical dopamine.
When cocaine is introduced, it binds to proteins that transport dopamine to produce euphoria.
During the study, rats self-administered cocaine by poking their noses through a hole where they would ingest a controlled dose of the drug. Through training, they…(continue reading)