Researchers who study the brain and addiction have long been interested in the role of dopamine and, if possible, how drug therapies might help those with addiction recover.
Dopamine is a neurotransmitter—a chemical that transmits information between neurons in the brain. Widely known for its role in creating pleasurable feelings, dopamine also “boosts mood, motivation, and attention, and helps regulate movement, learning, and emotional responses.” 
Opioids cause dopamine to be released in the brain and produces intense and pleasant feelings which the brain learns to desire again and again. This activity in the brain can be so intense that a person (or a rat in a lab) will use the substance repeatedly, even when that behavior causes problems in other areas of life. Often, relationships, work, school, and health all suffer because of the addictive behavior.
Because of the central role of dopamine in addiction, researchers have explored whether or not they could block the effect of opioids on the brain without hindering other essential brain functions. Specifically, researchers led by Dr. Zhi-Bing You and colleagues from the National Institute on Drug Abuse’s Intramural Research Program (IRP) and Johns Hopkins University have developed VK4-116, which blocks dopamine in a specific dopamine receptor in the brain called a D3 receptor. Their initial studies with rats have found that VK4-116 can reduce addiction-like behaviors related to oxycodone. 
In this study, rats were given access to levers, which infused oxycodone into their brains. Under normal conditions, the rats would continue increasing their oxycodone use, much like a person would increase the use of opioids over time. However, if the rats were pretreated with VK4-116, their oxycodone use did not increase at the same rate.
Researchers were also interested to learn whether VK4-116 interfered with the pain-relieving effects of oxycodone, which is essential because it is an effective and important pain killer. According to the research, they found VK4-116 did not reduce oxycodone’s pain-relieving effect and even enhanced it at the highest VK4-116 dose tested. Finally, in other experiments, the researchers have found that Vk4-116 may help alleviate withdrawal symptoms in addicted rats.
Researchers hope that VK4-116 and other agents that inhibit dopamine in the D3 receptor may prevent addiction for those prescribed opioids for pain and reduce the chances of relapse for those already addicted.
1. Psychology Today. (n.d.). Dopamine. Retrieved March 15, 2020, from https://www.psychologytoday.com/us/basics/dopamine
2. National Institute on Drug Abuse. (2020, January 13). Novel Dopamine D3 Receptor Antagonist Reduces Opioid Addiction-Like Behaviors in Rats. Retrieved March 15, 2020, from https://www.drugabuse.gov/news-events/nida-notes/2020/1/novel-dopamine-d3-receptor-antagonist-reduces-opioid-addiction-behaviors-in-rats?utm_source=daRSS&utm_medium=email&utm_campaign=da-researcherdigest
About the Author:
Travis Stewart, LPC has been mentoring others since 1992 and became a Licensed Professional Counselor in 2005. His counseling approach is relational and creative, helping people understand their story while also building hope for the future. Travis has experience with a wide variety of issues which might lead people to seek out professional counseling help. This includes a special interest in helping those with compulsive and addictive behaviors such as internet and screen addiction, eating disorders, anxiety, and perfectionism. Travis’ website is wtravisstewart.com
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Reviewed and Approved by Jacquelyn Ekern, MS, LPC on April 27, 2020
Published April 27, 2020, on AddictionHope.com