Background: Several endogenous factors regulate the perception of pain. Understanding of pain-alleviating mechanisms is increasing, which is useful both for doctors who treat pain-ridden patients and for researchers interested in the physiology of pain. This article provides an overview of such mechanisms.
Material and methods: This review article is based on literature identified through a non-systematic search in PubMed.
Results: Endogenous pain-alleviating mechanisms are mainly controlled by different parts of the reticular substance, and are normally activated by painful stimulation. Expectation of pain reduction (placebo analgesic effect), painful stimulation in other sites and high blood pressure are examples of factors which may increase the body's endogenous pain-alleviating mechanisms. Opioid-sensitive cells in the brain stem are important for endogenous pain alleviation. Reduced endogenous pain alleviation is found in a number of painful conditions, but it has not been clarified whether reduced endogenous pain inhibition is a cause of or a result of chronic pain.
Interpretation: Strengthening of the body's own mechanisms for pain alleviation is possible and potentially useful in treatment of pain-ridden patients.