How do opioids work to relieve pain? Opioids work in the brain by binding to special sites called opioid receptors located there. There are three main types of opioid receptors: The mu, the delta and the kappa. It’s the mu that’s most associated with drug addiction because it produces physical dependence and the euphoria so coveted by drug abusers. The mu is also closely linked to sedation and overdose. When too much of an opioid is taken, receptors in the brain stem become overrun. Since the brain stem controls critical life support functions like breathing, an opioid overdose can cause death by disabling the breathing mechanism.
The delta and kappa receptors appear to be related to mood and feelings of reward. The kappa may also be involved with dysphoria, the opposite of euphoria. Opioid receptors are located in the brain, the immune system, the skin and the stomach and intestines. These receptors likely have other functions not yet well understood. However, only opioids that can cross the blood-brain barrier can cause euphoria, pain relief, sedation and death by respiratory depression.
The Body’s Own Opioids
The body also has endogenous opioids. This means the body actually manufactures substances nearly identical to morphine and other opiates and opioids. Endogenous means something from within. Therefore, the opioids we take are called exogenous opioids, that is, those that originate from outside the body. Endogenous opioids are called endorphins and activate the brain’s opioid receptors in much the same way as exogenous opioids do. However, endorphins are produced only in small amounts. Their release may be triggered by injury or even acupuncture and intense exercise, the so-called runner’s high.
The opioid receptors located in the stomach and intestines respond to exogenous opioids by slowing the emptying of the stomach and the passage of food through the intestines. This is why they cause such severe constipation. This constipation has historically been very resistant to treatment, but newer drugs are now available that are quite effective in restoring normal function. These drugs work by targeting the intestinal opioid receptors, blocking any exogenous opioids from docking there. They don’t interfere with pain relief in the brain, though, because they cannot cross the blood-brain barrier.
When opioids bind to opioid receptors, they are thought to relieve pain by interfering with pain messages sent by the body’s cells to the brain. They probably also relieve pain by changing the perception of it. This makes sense because we know that opioids definitely affect mood. However, not everyone who takes an opioid will find the experience to be pleasant. They don’t cause euphoria for everyone. In fact, some people feel anxious and depressed while under the opioid influence.
A Short History of Opioids
Opiate use is very, very old. The ancient Egyptians knew about opium and used it for pain. Of course, they didn’t understand why it worked; they just knew it did. The answer to that riddle didn’t come until the first few years of the nineteenth century when a German chemist isolated morphine from opium. He named the new miracle painkiller morphine after Morpheus, the Greek god of dreams. Heroin, a semi-synthetic compound, was created later in that same century in about 1898 by a chemist working for Bayer. It was heralded as a miracle cure for “soldier’s disease,” which was actually the morphine addiction that ran rampant among men wounded in the Civil War just some thirty years earlier. It didn’t take long for Bayer to realize that heroin was even more addictive than its parent drug morphine.
Twice as strong as morphine and capable of producing a highly pleasurable sensation called a rush, heroin was available over the counter in various patent medicines and by mail order until 1914, when it was placed into a prescription only category. That didn’t really do too much to stop the addiction problem, though. Heroin was outlawed altogether in 1924, and it remains illegal in the United States to this very day.
Interestingly, there have been reports of parrots invading opium fields. These parrots wait in the trees until all human workers are gone. They have learned not to squawk while they wait. When it’s safe, they attack the opium poppy pods, tearing them open and eating the pods, seeds and sap. Opium field workers report dead parrots on the ground and others in trees too intoxicated to fly.
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If you have any questions about opioids or need help for you or a loved one, just call us anytime at 833-820-2922. We’re a group of professional drug counselors here to help you 24 hours a day and give you hope and help for any drug addiction issue.