Opioid Dependence Permanently Changes How The Brain Processes Emotion

With the United States in the midst of an opioid crisis, researchers from the University of California San Diego School of Medicine have turned their attention to studying what opioid dependence does to the brain.

In their paper published in the Proceedings of the National Academy of Sciences, researchers found that the central nucleus of the amygdala (CeA)–the part of the brain responsible for “conscious perception of emotion“–had irreversible changes. More specifically, they found that long-term use of opioids caused a suppression of the nociceptin system (N/OFQ), which is responsible for modulating pain.

The researchers believe this discovery could be a game changer for how opioid abuse is treated, something that is sorely needed. They stated, “The development of small molecules that target the N/OFQ system may have therapeutic efficacy for the treatment of opioid use disorder.”

The Opioid Crisis

Opioids are either derived from the opium plant or made synthetically, and they are commonly used as prescription pain killers, such as hydrocodone, fentanyl, oxycodone, tramadol, etc. Heroine is a commonly used illegal opioid.

Beginning in the late 1990’s, pharmaceutical companies began developing and pushing new types of synthetic opioids, assuring doctors and patients that they were not addictive enough to warrant concern. Because of this, opioid prescriptions soared. Within a few years, though, many of these unsuspecting patients found they couldn’t quit so easily, as they had developed a dependency.

When legal supplies of opioids ran dry, these people turned to illegal sources, thus exposing them to unregulated and dangerous products.

The statistics are alarming. According to the Center for Disease Control (CDC), nearly 200 million opioid prescriptions are written each year. Close to 50,000 people a year lose their lives to an opioid associated overdose, including many celebrities, and this has been increasing at almost 10% per year, with no end in sight. According to addictioncenter.com, roughly 2 million people abuse opioids for the first time each year, with 5% of these graduating to heroin.

Because of numbers like these, the CDC and the president officially declared it a public health emergency in October, 2017.

A New Treatment

Treatment for opioids currently involves the medications methadone, buprenorphine, and naltrexone. Methadone and buprenorphine are opioids themselves, which are used to ween a patient. Naltrexone is used in conjunction with these two, as it blocks the effects of the opioid. An abundance of research demonstrates that they are effective when used together, although for only a fraction of those suffering from opioid dependency. These medications can also cause serious long-term damage.

Researchers from the University of California San Diego School of Medicine believe they have discovered a new avenue which may lead to new types of medication. In their study, they found that the nociceptin system of the CeA is heavily involved in the complex chemistry of opioid addiction.

When the brain develops a dependency for opioids, the receptors of the nociceptin system of the CeA become permanently suppressed. This means the patient loses the ability to effectively modulate pain, as well as other emotions. The researchers also found that this leads to an increase in activation of GABA receptors. GABA receptors, to drastically oversimplify them, are responsible for inhibiting the activity between neurons. When they are over-activated, the brain is no longer able to regulate itself. The researchers believe both of these problems underpin opioid dependence.

Therefore, the researchers have been experimenting with various chemical mixtures to reactive the nociceptin system of the CeA. So far, they have been largely successful when dealing with rats that have been systematically addicted to oxycodone. Unfortunately, their brains do not show signs of being repaired, although it is clear that the medication allows them function more normally.

They are confident these results will translate to humans, offering not just different but safer medication to treat opioid dependency, possibly saving tens of thousands of lives a year.

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