Searching for a New Treatment for Heroin Addiction
In a number of research projects funded under the Programme on Alcohol and Drug Research at the Research Council of Norway, researchers are hoping to uncover the reasons why heroin brings such a pronounced effect to users of the drug. Years ago, it was discovered that heroin itself is inactive at the opioid centers of the brain. Despite that fact, it was unclear how the heroin high and feelings of pain relief are manifested almost immediately after the drug was administered. Upon understanding those mechanisms, it is hoped that a new treatment for heroin addiction can be created.
This group of studies was conducted and headed by Dr. Jorg Morland, who is both a senior researcher at the Norwegian Institute of Public Health and a professor emeritus at the University of Oslo. Through his study of both rats and mice, he and his research colleagues have uncovered new findings that may be significant to the development of new treatments for heroin addiction.
The Theory Behind How Heroin Affects the Brain
There has been a widely-held theory that heroin metabolizes quickly and passes into the brain. From there, it is converted into morphine and the user is actually feeling the effects of morphine. However, this current body of research shows that heroin undergoes a number of chemical changes on its way to the brain. Upon injection, the innate compound that is heroin metabolizes into a compound called 6-MAM (6-Monoacetylmorphine).
The process of metabolizing heroin into the 6-MAM compound is almost completed within minutes of injection. 6-MAM than crosses the blood/brain barrier and heroin as such only crosses this barrier to a very small extent. Thirty minutes after injection, the 6-MAM compound is the predominant substance both in the blood and brain. The presence of 6-MAM also results in the signaling of dopamine in certain areas of the brain. Dopamine plays a critical role in the reward effects.
An hour or so after injection, most of the 6-MAM compound has been converted into morphine. Morphine becomes the primary component over the next few hours and acts rapidly on bodily functions. However, approximately 6 to 12 hours after injection, the effects noted and felt are the result of the metabolite morphin-6-glucuronide, which is a metabolite formed from morphine.
Looking for New Treatment for Heroin Addiction
As noted by Dr. Morland, the current approach used as treatment for heroin addiction, especially in Norway, is through the use of methadone, subutex or subuxone. These substances are synthetic in nature; however, they are addictive in their own right. There may be also possibilities of developing an antibody that makes 6-MAM too large to cross the blood/brain barrier. There, however, have been studies in the effectiveness of naltroxone as a treatment for heroin addiction. Naltroxone is a non-addictive opioid antagonist that blocks the effects of opiates in the brain.
In a study funded by both the National Institute on Drug Abuse (NIDA) and the Australian Research Council (ARC), Researchers from the University of Colorado and the University of Adelaide (Australia) that the use of (+)-naloxone will selectively block the immune-addiction process and could be a valuable tool in the treatment of heroin addiction. The study was published in last month’s edition of the Journal of Neuroscience.
The use of naloxone as a possible treatment for heroin addiction focuses on blocking addiction through the immune system and not through the brain. Researchers in this study found that a certain immune receptor called TLR4 (Toll-Like Receptor 4) can attract opioid drugs like morphine and heroin in ways similar to the normal immune response to bacteria in our bodies. In this case, however, the TRL4 receptor acts as an amplifier for the addiction.
(+)-naloxone, used as a treatment for heroin addiction, shuts down the addictive properties associated with use of morphine and heroin through the immune system, thus cutting out the behaviors associated with addiction. It would assist with pain management without the addictive properties. Most importantly, there would be no production of dopamine to reinforce rewards from use of those drugs such as morphine or heroin.
Another possible treatment for heroin addiction is the use of a “heroin vaccine”. Scientists at the Scripps Research Institute (TSRI) had reported in May there had been successful preclinical trials of a new vaccine that targets heroin and the psychoactive products (such as 6-MAM) in the bloodstream, preventing those compounds from crossing the blood/brain barrier.