This article is written from a medical standpoint due to content and may not be easy to follow.
Endorphins ("endogenous morphines") are opioid like peptides that function as neurotransmitters and are produced by the pituitary gland and hypothalamus in the brains of all vertebrates. This natural analgesic is secreted from these areas of the brain in response to exercise, excitement, pain, eating spicy food, and sexual activity. They resemble exogenous opiates (morphine, opium, etc...) in their ability to create a sense of well being, and reduce pain.
Endorphins secreted into the blood have little influence on the brain because this molecule is too large to pass through the blood-brain barrier. The endorphin secreted by the hypothalamus in the brain does, however preferentially bind the μ1 opioid receptor of the brain. This is the same receptor that is bound by exogenous opioids like heroin and morphine. When endorphins or opium or opium derivatives bind this receptor pain relief, euphoria and a sense of well being is the result.
There is also evidence that endorphins have a role in dissociative disorder. Common descriptions of this psychological state include feeling disconnected from one's physical body. The patient may also report feeling as though they are not completely occupying their body or that they are not in control of their speech or physical movements. The patient may also endorse feeling detached from their thoughts and emotions and a feeling a disconnection from their body. Conversely, the drug Naloxone (Narcan) is an opioid receptor antagonist that reverses and blocks the effects of opioids in the brain. Naloxone has been effective in treating patients with dissociative disorder lending evidence to the role of endorphins in mediating this psychological state.
The classic signs of opium intoxication are decreased mental status, slowing of the respiratory rate, shallow breaths, decreased bowel sounds and constricted pupils. The most recognizable feature of intoxication is decreased respiratory rate. A respiratory rate less than 12 in a subject where opioid intoxication is a possibility almost assures the diagnosis. The subject’s heart rate may be normal to low. A fall in blood pressure is possible and this hypotension may be the result of opium intoxication and histamine release. The patient’s temperature may be lower than normal because of an impaired ability to produce heat and this can result in tell tale goose flesh. Any patient that appears more than mildly intoxicated should have their core temperature assessed. Core temperature means rectal temperature. The patient’s mental status changes can range from euphoria to coma. A very late finding that may result from lack of oxygen due to poor ventilation is seizure activity. Again, this is a late finding in a patient that is comatose with a prolonged respiratory rate with shallow breaths.
The concept of endorphin rush, or “runner’s high” is well accepted as a concept in the medical literature. The concept of endorphin shock or endorphin overload by contrast is a concept of which medical professionals have only recently become aware.
The “runner’s high” is actually a misnomer because its effects can be caused by any number of stimuli. The theory of acupuncture’s role in pain relief are thought to be mediated by endorphins. This theory has been studied and the evidence for endorphins role in pain relief is that these effects are blocked by antagonists, like Naloxone. Any stimulus that excites free nerve endings, pain fibers, will cause endorphin release. This stimulus can be strenuous exercise, the various inflammatory mediators released during infection or injury or an intense scene. Some practitioners of the BDSM arts refer to it as “flying” or sub space.
Consider the anecdotal reports of subjects that have flown. Common experiences are analgesia, euphoria, and in exceptional cases, feelings of an outer body experience (dissociation) or altered mental status. All of the anecdotal effects of flying can all be accounted for by the established effects of endorphins.
Shock is caused by severe declines in blood pressure and the resultant lack of perfusion of organs. Eventually, oxygen consumption by organs outpaces oxygen delivery. This results in lactic acid build up. Lowering of PH leads to cell death, end organ damage and eventually multi-system failure and death. Searches for endorphin shock, endorphin overload or overdose yield no results in the medical literature. Similarly, there have been no case reports in the medical literature of hypotension from the effects of endorphins. There have been several animal studies on the effects of endorphins on peripheral circulation and survival rates when septic shock is induced. The conclusions demonstrate that endorphins are vasoconstrictors that increase the resistance in peripheral circulation. This is the exact opposite of the effects that are required to induce shock.
There is abundant evidence supporting the concept of endorphin rush. All of the commonly described effects of this rush after an intense scene can be accounted for by endorphins’ effect on the brain and body. There is really no evidence that endorphin shock or overload is a real phenomena. It would be erroneous to attribute a subject’s behavior after an intense scene to a massive overdose of endorphins. There is a range of reported responses in the subject experiencing endorphin rush, but none of them are inherently life threatening.
It is very important that players, DMs, and EMTs are all aware of the symptoms and treatment of endorphin shock so that it can be assessed and dealt with appropriately.