Encephalin: Definition, Types, Functions, Location, Benefits, Negative Effects and Related Diseases

They are compounds (pentapeptides) found in all vertebrate animals, including humans.

Encephalins are produced naturally within organisms.

Encephalins are commonly found throughout the brain, in the spinal cord, and within the adrenal glands.

In addition, multiple studies in animals and humans have shown that they are present in nerves outside the brain, small and large intestine, kidneys, testes, pancreas, heart muscle, skin tissue, lungs, tissue joint, and bone tissue.

Types of enkephalins

There are two types of enkephalins:

  • Methionine (Met-encephalitis).
  • Leucine (Leu-enkephalin).

Functions of enkephalins

The role of enkephalins has been extensively studied and continues to develop as more specific antagonists and agonists are discovered.

In general, enkephalins play a role in neurotransmission and pain modulation.


Their role as neurotransmitters was initially determined from localization studies in which immunohistochemical mapping revealed that enkephalins were very close to the autoradiographic mapping of opiate receptors.

The cellular localization of enkephalin suggests that its function was to act on opiate receptors located at the terminals of sensory pain fibers and to inhibit the release of neurotransmitters such as substance P, vasopressin, or dopamine.

Along with the inhibitory role of enkephalins in preventing the release of transmitters, there is the modulatory role of enkephalins in altering calcium influx.

Direct hyperpolarization of neurons by enkephalins supports their inclusion in the long list of neurotransmitters. However, enkephalins have been implicated in various functions in addition to “classical” neurotransmission.


Encephalins are found in the brain’s thalamus and some spinal cord parts that transmit pain impulses.

In the spinal cord, enkephalins inhibit pain sensations by reacting with specific receptor sites on sensory nerve endings.

Nerve endings in the central nervous system (CNS) and the adrenal medulla release these naturally occurring morphine-like substances. Encephalins bind to opiate receptors and release controlled levels of pain.

Leu-enkephalin is an endogenous agonist for receptors that are stimulated by opiate alkaloids. It has multiple effects on the CNS, including the neuroendocrine hypothalamus. Leu-enkephalin also controls gonadal function.

Met-enkephalin is involved in phenomena associated with the modulated perception of pain, the regulation of memory and emotional conditions, the consumption of food and liquids, and the regulation of the immune system.

It also impacts the motility of the digestive system, gastric and pancreatic secretion, and carbohydrate metabolism.

Encephalins and pain suppression

Encephalins work to suppress pain. The goal of pain suppression is to allow the body to cope with pain without losing focus, rather than allowing the perception of pain to flood the system and cause panic, distress, or confusion.

These neurotransmitters are released by the brain and central nervous system when the brain senses pain.

In addition to reducing pain, usually in the short term, enkephalins also change the way people perceive pain.

This can be important, as people can still panic or freak out even when the pain is dull, a problem that commonly occurs when people are given synthetic pain relievers that relieve pain without addressing the underlying emotions.

Because these neurotransmitters can influence perception, they can also play a role in memory and mood formation.

They can also influence appetite and the functioning of the digestive system. These physical and emotional changes can benefit someone experiencing pain, making the release of enkephalins an essential part of the body’s response to sources of pain and injury.

These polypeptides are classified as endorphins, among the family of compounds that create a “fever” in the body.

Like the many other substances secreted by the body to transmit signals through the nervous system, enkephalins are released automatically when the body senses that they are needed.

People cannot control the time or amount of release of a neurotransmitter, and the compound acts instantly to perform its function as soon as necessary.

The rapid response time involved can be critical for many neurotransmitters, as circumstances in the body are constantly changing, so it is essential to send the proper signal at the right time.

Encephalins bind to opium transmitters in the body. This trait allows them to manage pain effectively, but it can also make them addictive.

Numerous studies have shown the addictive and behavior-modifying qualities of enkephalins, and these effects are significantly increased when people use synthetic pain relievers that bind to the same receptors.

Addiction is, in fact, a significant concern when painkillers are administered to a patient, as a doctor wishes to provide painkillers without the patient being dependent on them in the future.

Health benefits of high levels of enkephalins

  • They can prevent the growth of cancer cells.
  • They can reduce inflammation.
  • They can increase metabolism.
  • They help create “Runner’s High.” Describes the temporary state of euphoria that athletes reach after long-running or continuous exercise periods.
  • They can benefit the heart.
  • They can help with depression.

Adverse effects of high levels of enkephalin

  • They decrease the activity of immune cells.
  • They can inhibit the release of insulin.
  • They can promote binge drinking.

Diseases related to high levels of enkephalin

  • They can make symptoms of Alzheimer’s disease worse.
  • Cancer cells secrete enkephalins that suppress the immune system.
  • They can play a role in diabetes.
  • They may be related to psoriasis.