title: Stress-induced analgesia: neural and hormonal determinants.
abstract: Extensive evidence has indicated that distinct neural systems specifically designed to inhibit sensitivity to painful stimuli exist. Recent advances suggest that the endorphins, enkephalins and the opiate receptor interact with a descending serotonergic bulbospinal system to mediate the analgesic responses to opiates and electrical stimulation. In assessing the evolutionary and behavioral significance of this pain-inhibitory system, several laboratories discovered that acute exposure to a wide variety of stressful events results in a transient analgesia. Chronic exposure to a number of these stressors results in adaptation of the analgesic response. The purpose of this review is to identify and characterize the mechanisms by which these stressors activate pain-inhibition. The relationship of stress-induced analgesia to each of the following is reviewed: (a) the role of endorphins, enkephalins and the opiate receptor; (b) the role of the descending serotonergic bulbospinal system; (c) the role of the pituitary gland; and (d) the role of hypothalamic mechanisms. Data will be discussed in terms of "opiate" and "non-opiate" pain-inhibitory mechanisms, in which some stressors act through the former and other stressors act through the latter.
mesh_terms: D000698:Analgesia; D000818:Animals; D002490:Central Nervous System / Q000503:physiopathology*; D003847:Deoxyglucose / Q000494:pharmacology; D004357:Drug Synergism; D004361:Drug Tolerance; D004525:Efferent Pathways / Q000503:physiopathology; D006728:Hormones / Q000502:physiology*; D007031:Hypothalamus / Q000503:physiopathology; D008636:Mesencephalon / Q000503:physiopathology; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone; D010146:Pain / Q000503:physiopathology*; D010902:Pituitary Gland / Q000503:physiopathology; D011903:Raphe Nuclei / Q000503:physiopathology; D051381:Rats; D012684:Sensory Thresholds; D012701:Serotonin / Q000502:physiology; D013116:Spinal Cord / Q000503:physiopathology; D013312:Stress, Physiological / Q000503:physiopathology*; D013376:Substantia Gelatinosa / Q000503:physiopathology
chemical_list: D006728:Hormones; D012701:Serotonin; D009270:Naloxone; D009020:Morphine; D003847:Deoxyglucose