One of the most outstanding achievements in neurology was the discovery in the 70s of the neural mechanism of action of opiates. Research on this topic led to the discovery of a class of chemicals secreted by the brain, called endorphins, which obviously function as neurotransmitters. According to modern concepts, the action of morphine, heroin and other opiates is caused by stimulation of the action of the endorphin system in the brain. After reviewing the events that led to these discoveries, you can see how they help to understand the actions of the opiates.
One of the first events was the discovery by chemists in the 60s. the fact that the slightest change in the morphine molecule causes the creation of a chemical that not only does not produce any of the typical effects of opiates (relief of pain, euphoria), but, on the contrary, blocks the action of morphine and other opiates. This substance is called naloxone (Narcane) and can be qualified as an opiate antagonist. When naloxone was given to a patient suffering from a heroin or morphine overdose, he completely reversed the effects of these drugs. If naloxone is given to a heroin recipient, then heroin will have no effect. Obviously, naloxone has practical application in the treatment of opiate overdose and also has theoretical value. Since the chemical structure of naloxone is similar to morphine, the researchers suggested that these two drugs may act on some common brain receptor, and the effect of morphine on this receptor is blocked by naloxone. In the early 70s. two researchers from Johns Hopkins University in Baltimore, Candace Perth and Solomon Snyder reported on the discovery of brain receptors that selectively respond to the effects of opiates and called them “opiate receptors.” The existence of such receptors has caused great interest. It may be reasonable to ask why there are neurons in the brain responsible for the effects of such drugs. Did nature itself push people to become addicted to heroin? The presentation of neurologists on this subject varied greatly. They believed that the presence of such receptors should mean that there are natural substances in the brain with a structure and properties resembling morphine. The scientific search began for “natural brain opiates” and in 1975 several such substances were discovered. Although several morphine-like substances were found in the brain (beta-endorphin, enkephalin, dinorphin – the most important among them), the whole complex of these peptides is collectively called endorphin (short name for endogenous morphine).
The scientific questions caused by the discovery of endorphins focused on why the brain is provided with its own morphine, what function they perform. Most researchers began with the premise that because opiates mimic the activity of endorphin by stimulating the opiate or endorphin receptors in the brain, endorphins should have many properties similar to opiates, such as the ability to relieve pain or pleasure. Perhaps the main function of endorphins is to serve as part of the natural pain relief system. According to modern concepts, certain types of pain or stress cause the release of endorphins, and an analgesic effect occurs. Such an approach may help explain why under certain circumstances, for example, on the battlefield or in a big sport, a person can withstand severe injuries without feeling pain for at least some time. Pain relief from acupuncture (through needle insertion) may also be caused by the release of endorphin, since the use of naloxone negates the anesthetic effect of acupuncture. Since the main action of naloxone is blocking endorphin receptors, the anesthesia, negated by naloxone, is strong evidence that acupuncture needles cause the release of endorphins and thereby reduce pain.
It seems that strength training causes the release of endorphins, and perhaps some of the positive effects of these exercises on your mood are also caused by the action of endorphins. Indeed, some researchers believe that “dependence” on exercise, which develops in some people, is due to the same mechanisms in the brain, due to which there is also a dependence on heroin! Does this mean that we will ever become addicted to the chemical substances of our own brain?