Understanding Opioid Receptors, The Opioid System, and the Risks for Opioid Addiction

The United Nations Office on Drugs and Crime estimates that around 2.1 million people in the United States are currently suffering from substance use disorders related to prescription opioids. Another nearly 500,000 are addicted to heroin, another opiate. Opioid addiction is, in the words of the Centers for Disease Control and Prevention (CDC), a national epidemic. The CDC estimates that about 91 Americans die every day from opioid overdose. This is more than four times the number of opioid-related overdose deaths since 1999. To get to the bottom of the ongoing opioid problem in the U.S, one must first understand the brain’s opioid receptors and the opioid system.

Taking a Look at the Brain’s Opioid System

The opioid system is the part of the brain that controls feelings of pain, pleasure, and reward. It is also in charge of addictive behaviors. Neurons in the brain release a family of endogenous peptides, such as endorphin and dynorphins, during activities such as eating, sleeping, exercising, and sexual activity. These peptides activate opioid receptors in the brain, triggering the reward system and generating feelings of pleasure and happiness. The opioid system is the brain’s way of keeping the body alive – offering rewards for activities necessary to sustain life.

The opioid system contains three G protein-coupled receptors: mu, delta, and kappa. It is these three receptors that the release of peptides stimulates in the brain. Mu receptors trigger the brain’s reward system. Studies suggest that it is the mu-opioid receptor that initiates addictive behaviors. The delta receptor is in charge of emotional responses, such as depression and anxiety. These two receptors may hold the key to why people become addicted to opioid drugs – and how to stop addiction in the future.

How Opioids Work on the Brain

Taking a Look at the Brain's Opioid System

Opioids are a category of drugs that act on the brain’s opioid receptors to create feelings of euphoria. They include morphine, heroin, oxycodone, hydrocodone, codeine, and fentanyl. Opioids work by acting on the brain’s opioid receptors, activating them as the natural releases of peptides normally would. In this way, opioid drugs act as painkillers – and highly addictive recreational drugs.

When a person consumes opiates, they bind to the opioid receptors in the brain. This is possible because the chemical structure of opioids mimics that of the brain’s natural transmitters. Once attached, the drug blocks pain and slows down breathing, creating a clam and pleasant effect. The drugs do not activate the nerve cells the same way as natural transmitters – instead, they send abnormal messages through the brain’s opioid system. They flood the brain’s reward circuit with dopamine, a neurotransmitter that regulates feelings of pleasure, emotion, motivation, and cognition. It is the overstimulation of the reward system that leads to the euphoric feelings, or “high,” of consuming opiates.

Understanding Opioid Addiction

After consuming opiates, the brain associates them with pleasure. Opiates trick the brain into thinking taking the drug is a life-sustaining activity. This deception is what leads to a person wanting to take the drug again and again. Sometimes an opiate is strong enough to create this reaction after just a single use. When taken over a long period of time, opioids change the way the brain’s nerve cells function. Eventually, the user is unable to experience pleasure without the drug. At this point, the person is addicted. An opioid addict will experience unpleasant withdrawal symptoms without the regular use of the drug.

Opioids act on the body’s limbic system, brainstem, and spinal cord. The limbic system is responsible for controlling emotions such as relaxation, contentment, and pleasure. The brainstem controls the body’s automatic systems, such as breathing. Opioids in the brainstem can slow breathing and reduce feelings of pain. The spinal cord transmits sensations from the brain to the body and vice versa. Opioids on the spinal cord can decrease feelings of pain, such as after a serious accident. Injecting opioids into the bloodstream creates a faster, more intense reaction to the drugs. Taking an opioid by mouth results in slower effects, but is safer.

Opioids change the brain’s reward system, leading to addiction regardless of a person’s age, gender, or income. Opiate addiction does not depend on a person’s willpower, strength, or other dispositions, despite common misconceptions. Opiates are a dangerous and common substance for abuse. Understanding opioid addiction as a disease, and not a pitfall of a certain personality type or demographic, is the key to preventing addiction.

Opioid Addiction in America

The current opioid epidemic is due in large part to lax prescribing practices and lack of awareness and education about opioid addiction. Doctors around America issue prescriptions for strong painkillers to treat chronic pain and certain conditions, such as migraine headaches. Often, doctors fail to warn patients of the risk of addiction to prescription drugs. Patients typically do not associate prescription medications with drug abuse and addiction, since they are legal and given to them by a doctor. The combination of lack of addiction awareness and loose prescribing practices has led to the current opioid epidemic in the nation.

Heroin is just a step behind, with studies linking the increase in heroin use to the increase in prescription opioid addiction. According to the Drug Enforcement Administration (DEA), heroin use in the U.S. tripled from 2007 to 2014. The number of deaths involving heroin skyrocketed from 3,036 in 2010 to 10,574 in 2014. As of 2015, the DEA estimated there were about 600,000 heroin users in the U.S. Understanding opioid addiction is the first step toward reducing the opiate powerhouse overtaking America.

Hope for the Future

In spite of the frightening rise in opioid abuse and related deaths in recent years, there is hope for the future. Many states have enacted systems to monitor prescribing practices in an effort to limit the number of prescription opioids that go to patients. Drug awareness programs have sprung up around the country, as have treatment centers. If you or a loved one is struggling with an opioid addiction, get help. Contact The Treatment Center.

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