Annals of the New York Academy of Sciences, Vol 398, Issue 1 260-271, Copyright © 1982 by New York Academy of Sciences
The role of endorphins in stress-induced analgesia
D. D. Kelly
We have seen that exposure of an organism to any of a wide range of
stressful situations can induce alterations in sensitivity to pain that
outlast the exposure. Not all stressors induce analgesia; among those that
do not are some that produce maximal elevations in plasma beta-endorphin,
ACTH, and adrenal corticosteroids. Some examples of SIA are sensitive to
opiate receptor blockade by naloxone, but others are not. Hypophysectomy
produces a similarly uneven profile of effects across different stressors.
This diversity has often been interpreted as evidence for the existence of
an array of pain inhibitory systems, with differing physiological
properties and activated by different stressors. However, it might also
suggest that stressors can prompt a variety of behavioral changes, many of
which can be interpreted as analgesia if a pain reflex test is employed as
the dependent measure.
