What Are Endorphins?
Endorphins are natural opiates produced by the central nervous system in response to stimuli like pain or stress. The word ‘endorphin’ is derived from the two words ‘endogenou’, which means ‘produced within the body’, and ‘morphine’, a natural opiate.
A Brief History
In the 1960s researchers discovered that opiates like morphine could bind to specialized receptors in the brain. From this unexpected interaction they concluded that the body must produce its own natural opiates. Otherwise why would a receptor in the brain exist to target a chemical derived from the poppy? This line of reasoning led to the discovery of endorphins in the 1970s. Researchers isolated several small neuropeptides which were found to reduce pain.
Today we know of 20 different kinds of endorphins produced by the body. These include beta-endorphins, which have analgesic properties many times stronger than morphine. Surgical patients under anesthesia often produce a significantly higher number of beta-endorphins.
What Are Endorphins?
Endorphins are opiate peptides which are produced in the body. They have a similar structure to proteins, but with shorter sequences of amino acids. The smallest endorphins, such as met-enkephalin and leuenkephalin, are made up of just five amino acids. The largest endorphins can comprises as many as 40 amino acids. Beta-endorphins, one of only five endorphins produced in humans, has 31 amino acids in its sequence.
Endorphins are neuromodulatory, influencing how neurotransmitters respond to sensations of pleasure and pain. But endorphins themselves are not classified as neurotransmitters.
How Are Endorphins Released?
The body’s workshop where many of these endorphins are made is the pituitary gland. Composed of three lobes, the pituitary gland is a pea-sized protrusion linked to the hypothalamus at the base of the brain. The hypothalamus handles many emotional and physical responses, including hunger and sexual bliss.
Endorphins though are often triggered in response to pain. Pain receptors send signals made of a neuropeptide called Substance P to the dorsal horn of the spinal cord, and from there onto the hypothalamus. These signals are the pain we experience after a trauma.
The hypothalamus next signals the pituitary gland by releasing corticotroponin-releasing hormone (CRH). This triggers the pituitary gland to start making a large protein known as proopiomelanocortin (POMC). It is from this manipulation of the POMC protein that endorphins are created.
Enzymes act on the POMC and cut it up into several kinds of peptide sub-units. Of these it is the beta-endorphins and (to a lesser extent) met-enkephalin which are the powerful analgesics. Another peptide which is created is alpha-melanocyte stimulating hormone. MSH regulates appetite and sexual behavior.
The brain has evolved to keep a certain level of endorphins topped up to ensure survival in the face of stress. This is for the purpose of maintaining our Fight-or-Flight reaction. But the brain also knows when to recognize overproduction. When endorphin levels get too high, feedback inhibition will occur, the hypothalamus shuting off CRH production.
How Do Endorphins Work?
Beta-endorphins work as analgesics by binding to opioid receptors in
the brain and inhibiting Substance P production. This has the effect of reducing pain signals transmitted to the brain.
The hypothalamus responds a little differently to Substance P signals. It releases beta-endorphins through the brain’s periaqueductal grey. These act to inhibit the release of a chemical called GABA, which in itself is an inhibitor. In fact GABA is the main inhibitory neurotransmitter in the central nervous system. By reducing GABA levels, the body produces more of a neurochemical called dopamine. Together with the opiate endorphins, dopamine is part of the body’s ‘Quartet’ of happiness chemicals. The other two are serotonin and oxytocin.
Other endorphins act in a similar way to create feelings of pleasure or euphoria. It is the binding to select opioid receptors in the brain that creates these specific sensations. Whenever you experience a natural feeling of bliss, it will have been caused by endorphins doing their good work around your body.
Highs and Lows
Endorphins are a vital part of the brain’s reward system. A feeling of pleasure produced by the brain lets us know when we’ve had enough rich food, beer or sex, for example. We’re also left with memory of the feeling, which gives us the motivation to go out and get these nice things at a later date.
Different people react in different ways to endorphins due to physiological makeup. Some people produce more endorphins than others. With some, the levels of pleasure and pain reduction created by endorphins will vary.
People with low levels of endorphins may be less likely to be able to say no after experiencing pleasurable activity. These people may develop addictions to alcohol, drugs or sex. They may also be susceptible to pain, both physical and emotional. Obsessive or risk-taking behavior can increase if there are not enough endorphin
signals to tell the person that enough is enough. This is why some people with obsessive-compulsive disorder can’t stop washing their hands.
Pharmaceutical opiates, such as codeine and morphine, work in a similar way to the body’s natural endorphins, but with one difference. Manmade opiates can become addictive if their use is not moderated. When natural endorphins bind with the brain’s receptors, enzymes quickly break them down for recycling. Morphine, as an example, is more resistant to these enzymes, and continues to reactivate the opioid receptors unchecked. This not only intensifies the euphoric feelings and makes them last longer, but the risk of addiction increases too.
Endorphins And Exercise
Fortunately we don’t have to limit ourselves to the level of endorphins our usual daily activity allots us. Regular exercise is an excellent way to increase our feelings of euphoria without having to resort to pills.
Most people by now will have heard of the ‘runner’s high’. But any exercise involving short spurts of intense physical activity improves your wellbeing. That extra endorphin release leaves you more motivated, energized and protected from depression. Even less strenuous exercises such as Pilates and yoga are known to release endorphins and promote happiness.