Comparison of nociceptive behavior in prostaglandin E, F, D, prostacyclin and thromboxane receptor knockout mice

Eur J Pain. 2009 Aug;13(7):691-703. doi: 10.1016/j.ejpain.2008.09.001. Epub 2008 Oct 19.

Abstract

Antagonist at specific prostaglandin receptors might provide analgesia with a more favourable toxicity profile compared with cyclooxygenase inhibitors. We analyzed nociceptive responses in prostaglandin D, E, F, prostacyclin and thromboxane receptor knockout mice and mice deficient of cyclooxygenase 1 or 2 to evaluate the contribution of individual prostaglandin receptors for heat, mechanical and formalin-evoked pain. None of the knockouts was uniformly protected from all of these pain stimuli but COX-1 and EP4 receptor knockouts presented with reduced heat pain and EP3 receptor and COX-2 knockout mice had reduced licking responses in the 2nd phase of the formalin assay. This was accompanied with reduced c-Fos immunoreactivity in the spinal cord dorsal horn in EP3 knockouts. Oppositely, heat pain sensitivity was increased in FP, EP1 and EP1+3 double mutant mice possibly due to a loss of FP or EP1 receptor mediated central control of thermal pain sensitivity. Deficiency of either EP2 or DP1 was associated with increased formalin-evoked flinching responses and c-Fos IR in dorsal horn neurons suggesting facilitated spinal cord pain reflex circuity. Thromboxane and prostacyclin receptor knockout mice showed normal pain behavior in all tests. The results suggest a differential, pain-stimulus and site-specific contribution of specific PG-receptors for the processing of the nociceptive stimuli, a differential modulation of nociceptive responses by COX-1 and COX-2 derived prostaglandins and compensatory and/or developmental adaptations in mice lacking specific PG receptors.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclooxygenase 1 / genetics
  • Cyclooxygenase 1 / physiology
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / physiology
  • Female
  • Fluorescent Antibody Technique
  • Formaldehyde
  • Hot Temperature
  • Image Processing, Computer-Assisted
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pain / genetics
  • Pain / psychology*
  • Pain Measurement / drug effects
  • Physical Stimulation
  • Proto-Oncogene Proteins c-fos / metabolism
  • Receptors, Epoprostenol / genetics
  • Receptors, Epoprostenol / physiology
  • Receptors, Immunologic / genetics
  • Receptors, Immunologic / physiology
  • Receptors, Prostaglandin / genetics
  • Receptors, Prostaglandin / physiology*
  • Receptors, Prostaglandin E / genetics
  • Receptors, Prostaglandin E / physiology
  • Receptors, Thromboxane / genetics
  • Receptors, Thromboxane / physiology

Substances

  • Proto-Oncogene Proteins c-fos
  • Receptors, Epoprostenol
  • Receptors, Immunologic
  • Receptors, Prostaglandin
  • Receptors, Prostaglandin E
  • Receptors, Thromboxane
  • prostaglandin F2alpha receptor
  • Formaldehyde
  • Cyclooxygenase 1
  • Cyclooxygenase 2
  • prostaglandin D2 receptor