Endorphin

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Chemical structure met-enkephalin, an endorphin

Endorphins are proteins that are similar to opioids. They are made by the endocrine system of many vertebrates. When they are released into the body, they cause a sense of well-being. They also act as analgesics -- that is, they can fight pain.[1] They are sometimes named "natural pain killers". Endorphins were first found in 1970s. In 1977, Roger Guillemin and Andrew W. Schally won the Nobel Prize in medicine because of their studies on hormones in the brain, including endorphins.[2]

The term endorphin is a general name for many opioid-like proteins. (It consists of two parts: endo and orphin; these are short forms of the words endogenous metersorphine which means "a morphin-like substance which is produced by the human body".[3]) Special endorphins have their own names, like enkephalin and β-endorphin.

Types[change | change source]

Four types of endorphins are created in the human body. They are named alpha (α), beta (β), gamma (γ) and sigma (σ) endorphins. The four types have different numbers and types of amino acids in their molecules; they have between 16 and 31 amino acids in each molecule.

Beta-endorphins (β-endorphins) are the most powerful endorphins in the body. They are usually in the hypothalamus and pituitary gland. More endorphins are released in the pituitary gland during times of pain or stress. Exercise increases the endorphin release too. For the same reason, exercise results in a better mood.

Met-enkephalin and leu-enkephalin are in the brain stem and spinal cord; they are the pain killers of the spinal cord.[4] Both of them have five amino acids in their structure; the first four are similar, but the last one is different.

Action[change | change source]

All of the endorphins bind to the opioid receptors in the brain. Many of the analgesic (pain killer) drugs have a similar action in the brain. The main difference between the natural endorphins and the analgesic drugs is that natural endorphins are cleared from the blood very quickly. Endorphins are also involved in the release of sex hormones in the pituitary gland.[5] Also, scientists think that acupuncture results in the release of more endorphins.[6] Endorphins may have a role in obesity, diabetes and psychiatric diseases too.[7]

Endorphin rush[change | change source]

The term endorphin rush is sometimes used in normal speech to refer to a feeling of wellness caused by exercise, danger or stress.[8] However, it is not a medical term, and it is not proven that higher endorphin production after exercise really has a role in the wellness feeling.

Another term which is commonly used is runner's high. It refers to the feeling being "high" (full of energy and wellness) after exercise. It is commonly said that the "high" is a result of the release of bigger amounts of endorphins in the body during the exercise. However, some scientists think this feeling is caused by the challenge, and is not related to endorphin release.[9]

For example, in some studies a drug was given to people which blocked the effect of endorphins. These people still felt the runner's high; it means this feeling is not caused by the release of endorphins in the blood. Another study was performed in 2004, which showed this feeling is related to a different body chemical named "anadamide".[10] Anadamide is similar to one of the chemicals in marijuana. The body produces anadamide to fight with the stress and pain in a long exercise.

References[change | change source]

  1. Hartwig, AC (May-Jun 1991). "Peripheral beta-endorphin and pain modulation". Anesthesia progress 38 (3): 75-8. PMID 1814247.
  2. "The Nobel Prize in Physiology or Medicine 1977". http://nobelprize.org/nobel_prizes/medicine/laureates/1977/. Retrieved 2007-10-06.
  3. "Definition of endorphin". Merram-Webster dictionary. http://mw1.merriam-webster.com/dictionary/endorphin. Retrieved 2007-10-07.
  4. Guyton, AC; Hall, JE (2001). Textbook of Medical Physiology (10th ed ed.). WB Saunders. pp. 556.
  5. Bancroft, J (Sep 2005). "The endocrinology of sexual arousal.". The Journal of endocrinology 186 (3): 411-27. PMID 16135662.
  6. Best, Ben. "Brain Neuron Physiology". http://www.benbest.com/science/anatmind/anatmd1.html. Retrieved 2007-10-07.
  7. Dalayeun JF, Norès JM, Bergal S (1993). "Physiology of beta-endorphins. A close-up view and a review of the literature". Biomedicine & pharmacotherapy 47 (8): 311-20. PMID 7520295.
  8. "Runner's high". University of Pittsburgh Medical Center. http://www.sportsmedicine.upmc.com/MySportRunningHigh.htm#Endorphin. Retrieved 2007-10-18.
  9. Hinton E, Taylor S (1986). "Does placebo response mediate runner's high?". Percept Mot Skills 62 (3): 789-90. PMID 3725516.
  10. "Study links marijuana buzz to 'runner's high'". CNN. 2004-01-11. http://www.cnn.com/2004/HEALTH/01/11/marijuana.exercise.reut. Retrieved 2007-10-18.

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