Serotonin-containing neurons: their possible role in pain and analgesia.

Experimental evidence is reviewed showing that brain and spinal cord serotonergic neurons are involved in nociceptive responses, as well as in the analgesic effects of opiate narcotics. This evidence, based on studies employing pharmacological, surgical, electrophysiological, and dietary manipulations of central nervous system serotonergic neurotransmission, suggests that increases in the activity of brain and spinal cord serotonin neurons are associated with analgesia and enhanced antinociceptive drug potency, whereas decreases in the activities of these neurons correlate with hyperalgesia and diminished analgesic drug potency.