[Pain and endorphins]

Various stimuli may evoke the symptom pain. These stimuli activate sensory receptors and this information is transmitted to the spinal cord and a number of cerebral centres. Various endogenous analgesic systems are present in the body, which can modulate and control the consequences of pain stimuli to some extent. Endogenous morphine-like substances (endorphins) are an essential factor in some of these systems. Endorphins may be released in the body during stress or by acupuncture and other pain-relieving procedures (e.g. the twitch in horses). The significance of endorphins is not confined to pain, but they are also involved in reward systems of the brain may therefore play a role in eating, sexual, social and addictive behaviour among others.