Spinal inflammatory hyperalgesia is mediated by prostaglandin E receptors of the EP2 subtype

• Published in: The Journal of clinical investigation Vol. 115; no. 3; pp. 673 - 679
• Main Authors: Reinold, Heiko, Ahmadi, Seifollah, Depner, Ulrike B, Layh, Beate, Heindl, Cornelia, Hamza, May, Pahl, Andreas, Brune, Kay, Narumiya, Shuh, Müller, Ulrike, Zeilhofer, Hanns Ulrich
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.03.2005
• Subjects: Animals; Behavior, Animal - physiology; Biomedical research; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Female; Glycine - metabolism; Hot Temperature; Hyperalgesia - immunology; Hyperalgesia - metabolism; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neurons - metabolism; Pain - metabolism; Pain Measurement; Patch-Clamp Techniques; Prostaglandin-Endoperoxide Synthases - metabolism; Prostaglandins - administration & dosage; Prostaglandins - metabolism; Receptors, Prostaglandin E - genetics; Receptors, Prostaglandin E - metabolism; Receptors, Prostaglandin E, EP2 Subtype; Signal Transduction - physiology; Spinal Cord - cytology; Spinal Cord - physiology; Synaptic Transmission
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/jci23618

Blockade of prostaglandin (PG) production by COX inhibitors is the treatment of choice for inflammatory pain but is also prone to severe side effects. Identification of signaling elements downstream of COX inhibition, particularly of PG receptor subtypes responsible for pain sensitization (hyperalgesia), provides a strategy for better-tolerated analgesics. Here, we have identified PGE2 receptors of the EP2 receptor subtype as key signaling elements in spinal inflammatory hyperalgesia. Mice deficient in EP2 receptors (EP2-/- mice) completely lack spinal PGE2-evoked hyperalgesia. After a peripheral inflammatory stimulus, EP2-/- mice exhibit only short-lasting peripheral hyperalgesia but lack a second sustained hyperalgesic phase of spinal origin. Electrophysiological recordings identify diminished synaptic inhibition of excitatory dorsal horn neurons as the dominant source of EP2 receptor-dependent hyperalgesia. Our results thus demonstrate that inflammatory hyperalgesia can be treated by targeting of a single PG receptor subtype and provide a rational basis for new analgesic strategies going beyond COX inhibition.