Missing enzyme linked to drug addiction

June 17, 2013, The Endocrine Society

A missing brain enzyme increases concentrations of a protein related to pain-killer addiction, according to an animal study. The results will be presented Monday at The Endocrine Society's 95th Annual Meeting in San Francisco.

are pain-killing drugs, derived from the opium plant, which block signals of pain between nerves in the body. They are manufactured in like morphine and codeine, and also are found in some , like heroin. Both legal and illegal opioids can be highly addictive.

In addition to the synthetic opioids, natural opioids are produced by the body. Most people have heard of the so-called feel-good endorphins, which are opioid-like proteins produced by various organs in the body in response to certain activities, like exercise.

occurs, in part, because opioid-containing drugs alter the brain's biochemical balance of naturally produced opioids. Nationwide, drug abuse of opioid-containing prescription drugs is skyrocketing, and researchers are trying to identify the risk factors that differentiate people who get addicted from those who do not.

In this particular animal model, researchers eliminated an enzyme called prohormone convertase 2, or PC2, which normally converts pre-hormonal substances into active hormones in certain parts of the brain. Previous research by this team demonstrated that PC2 levels increase after long-term morphine treatment, according to study lead author Theodore C. Friedman, MD, PhD, chairman of the internal medicine department at Charles R. Drew University of Medicine and Science in Los Angeles.

"This raises the possibility that PC2-derived peptides may be involved in some of the addiction parameters related to morphine," Friedman said. For this study, Friedman and his co-researchers analyzed the effects of morphine on the brain after knocking out the PC2 enzyme in mice. Morphine normally binds to a protein on cells known as the , or MOR. They found that MOR concentrations were higher in mice lacking PC2, compared to other mice.

To analyze the effects of PC2 elimination, the researchers examined MOR levels in specific that are related to pain relief, as well as to behaviors associated with reward and addiction. They measured these levels using a scientific test called immunohistochemistry, which uses specific antibodies to identify the cells in which proteins are expressed.

"In this study, we found that PC2 knockout mice have higher levels of MOR in brain regions related to drug addiction," Friedman said. "We conclude that PC2 regulates endogenous opioids involved in the addiction response and in its absence, up-regulation of MOR expression occurs in key brain areas related to drug addiction."

The National Institutes of Health's National Institute on Drug Abuse funded the study.

Explore further: Scientists can now block heroin, morphine addiction; clinical trials possible within 18 months

Related Stories

Scientists can now block heroin, morphine addiction; clinical trials possible within 18 months

August 14, 2012
In a major breakthrough, an international team of scientists has proven that addiction to morphine and heroin can be blocked, while at the same time increasing pain relief.

A path to lower-risk painkillers

June 10, 2013
For patients managing cancer and other chronic health issues, painkillers such as morphine and Vicodin are often essential for pain relief. The body's natural tendency to develop tolerance to these medications, however, often ...

Opioid prescription is on the increase

February 12, 2013
More and more opioids are being prescribed for pain relief in Germany. This is the conclusion arrived at by Ingrid Schubert, Peter Ihle, and Rainer Sabatowski, whose study of a sample of inhabitants of the state of Hesse ...

Safe, long-term opioid therapy is possible

March 5, 2013
In a Clinical Crossroads article featured in the March 6, 2013 issue of the Journal of the American Medical Association (JAMA), Dr. Dan Alford from Boston University School of Medicine (BUSM) and Boston Medical Center (BMC) ...

Heroin addicts have higher pain sensitivity, even during treatment

April 25, 2012
(HealthDay) -- Heroin addicts often have an increased sensitivity to pain, and this sensitivity does not subside over the course of treatment with methadone or other opioids, new research finds.

Recommended for you

Cannabinoids are easier on the brain than booze, study finds

February 9, 2018
Marijuana may not be as damaging to the brain as previously thought, according to new research from the University of Colorado Boulder and the CU Change Lab.

Marijuana use may not aid patients in opioid addiction treatment

December 4, 2017
Many patients who are being treated for opioid addiction in a medication-assisted treatment clinic use marijuana to help manage their pain and mood symptoms.

For opiate addiction, study finds drug-assisted treatment is more effective than detox

November 23, 2017
Say you're a publicly insured Californian with an addiction to heroin, fentanyl or prescription narcotics, and you want to quit.

Study finds medical cannabis is effective at reducing opioid addiction

November 17, 2017
A new study conducted by researchers at The University of New Mexico, involving medical cannabis and prescription opioid use among chronic pain patients, found a distinct connection between having the legal ability to use ...

Insomnia linked to alcohol-use frequency among early adolescents, says new psychology study

November 8, 2017
Insomnia is linked to frequency of alcohol use among early adolescents, according to new Rutgers University–Camden research.

Large declines seen in teen substance abuse, delinquency

October 25, 2017
More than a decade of data indicates teens have become far less likely to abuse alcohol, nicotine and illicit drugs, and they also are less likely to engage in delinquent behaviors, such as fighting and stealing, according ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.