Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 27, 2004
Publication Date: N/A
Technical Abstract: Endorphins, alpha-endorphin, beta-endorphin, and gamma-endorphin, are endogenous morphine-like substances with a similar chemical structure and analgesic function as morphine (endorphin is a short term for endogenous morphine). Endorphin is the basis of a diverse system (opioid system) associated with physiological function and pathological disorders. As components of an intrinsic pain suppression system, endorphins are involved in regulating the pathogenesis of pain. Activation of the endorphin system triggers an endogenous analgesia cascade by modulating nociceptive signals within the local circuits, such as in the dorsal horn of the spinal cord (the gate control theory of pain), resulting in reducing or inhibiting nociceptive messages forwarded to the somatosensory system. Endorphins, similar to other endogenous opioid peptides, is sensitive to different stress factors. Activation of the opioid system is one of the most effective ways to provide protective function for an organism to physiologically and pathologically adapt to stressors. In addition, endogenous endorphins act within the brain to mediate reproductive function. Endorphins inhibit the release of gonadotrophin secretion, such as luteinizing hormone (LH) released by the pituitary gland. Endorphins also play an important role in regulation of feeding behavior and maintaining energy homeostasis. Furthermore, endogenous endorphins, as modulators, are involved in the crosstalk between the nervous and immune systems directly or indirectly through the hypothalamic-pituitary-adrenal axis.