Endorphins are opioid peptides synthesized by the body itself, which have an influence on the sensation of pain and hunger and can very likely also trigger euphoria. It is certain that endorphins are released by the pituitary and hypothalamus in painful emergency situations and, for example, during endurance sports at peak performance. It is very likely that endorphins are also released after positive experiences as part of the active reward system.
What are endorphins?
The term endorphin is an acronym composed of the syllable endo, synonymous with inside, and the noun morphine. The term is meant to suggest that it is a substance similar to morphine that is produced internally, by the body itself. In fact, three different endorphins, alpha, beta and gamma endorphin, are known to be synthesized on demand in the pituitary and hypothalamus. They are neuropeptides with known amino acid sequences. The endorphins, also called opioid peptides, dock as neurotransmitters at the same receptors as opiates and thus inhibit the activity of the pain-transmitting neurons. This means that the pain information, which all converges in the spinal cord to be transmitted from there to the brain, is no longer fully reported to the brain. Beyond their pain-inhibiting effects, endorphins play an important role in the reward system. The connection has not yet been sufficiently scientifically clarified. It is considered very likely that endorphins, in their capacity as neuromodulators, can activate the synthesis of the so-called happiness hormone dopamine.
Anatomy and structure
Endorphins are produced by the body itself when needed. They are substances that can dock to the opioid and opiate receptors of the synapses of pain-transmitting afferent neurons like natural opiates, leading to a reduction in pain reporting to the brain. Because endorphins are composed of short-chain peptides, i.e., a stringing together of amino acids via peptide bonds, they are also known as opioid peptides. Endorphins are produced in the pituitary and hypothalamus and are formed there by degradation and breakdown of proenkephalin-A and B and from degradation and breakdown of proopiomelanocortin. Enkephalins are endogenous pentapeptides consisting of a sequence of five amino acids, each distinguished by the 5th amino acid. Similar to long-chain proteins, neuropeptides are synthesized from a sequence of amino acids determined by genes. Proopiomelanocortin is a prohormone, i.e. hormone and protein inactivated by an altered spatial structure, which is synthesized not only in the pituitary and hypothalamus, but also in placental cells and in certain epithelial cells. It can be converted to alf-, beta-, and gamma-endorphins in the pituitary and hypothalamus and converted to the active form.
Function and roles
In simple terms, pain sensations represent an important protective function of the body. Nociceptors in certain tissues signal “pain” when lesions have occurred or are imminent to signal that injury has already occurred or that injury is imminent. This means that the person learns from this to avoid such situations in the future or to stop a process that could lead to an injury. However, situations are also conceivable in which injuries or lesions must be tolerated in order to save the individual as a whole. This may be the case, for example, during escape from a burning tunnel or when attempting to reach a rescue station despite severe injuries such as broken legs or open wounds. In these and similar cases, the protective function of pain can prove counterproductive. Our body can release endorphins in such situations to briefly suppress pain sensations and at the same time produce euphoric, anxiety-suppressing, feelings. While the biochemical process of pain suppression is well explained, the processes surrounding the generation of euphoric feelings by endorphins are not yet sufficiently understood. The release of endorphins can also be activated by strong imagination. Long-distance runners are familiar with the problem that after a certain time pain sets in and the motivation to continue the run comes under pressure. The body tries to get the athlete to give up.However, many long-distance runners manage to overcome the situation by imagining the positive effects if they persevere. The body then switches and releases endorphins, the pain decreases and euphoric feelings set in. In addition, it is also discussed that endorphins also play an important function in daily normal situations in establishing the balance between the neurotransmitters serotonin and dopamine within the dopaminergic reward system.
Diseases
Diseases and disorders related to endorphins are either due to pathologically decreased secretion of the endogenous opioid or the receptors of the synapses to which the endorphins are supposed to dock show dysfunction. The effects are comparable in both cases, and the boundaries to pathological behavior, which can be triggered by a reduced endorphin release, are fluid. For the past few years, diagnosed disorders such as borderline personality disorder (BPD) and self-injurious behavior (SVV), as well as anorexia, have been associated with impaired or decreased secretion or efficacy of endorphins. Self-injurious behavior can become addictive in sufferers because self-injury causes short-term release of endorphins and triggers short-term positive feelings. Similar mechanisms are considered in anorexia and in BPD. It is very likely that sufferers do not want to punish themselves, but seek reward through happy hormones.
