Role of periaqueductal grey prostaglandin receptors in formalin-induced hyperalgesia.

Abstract

In this study we have investigated the role of periaqueductal grey prostaglandin receptors in formalin-induced hyperalgesia in mice. Glutamate and GABA release changes have been monitored by in vivo microdialysis. Intra-periaqueductal grey microinjections of misoprostol, a non-selective prostaglandin receptor agonist, increased nociceptive responses in the formalin test only during the late phase. Prostanoid EP(1) (L-335677), EP(2) (AH 6809), EP(3) (L-826266) and EP(4) (L-161982) receptor antagonists prevented the nociceptive response induced by misoprostol in formalin-injected mice. Prostanoid EP(1), EP(2), EP(3) and EP(4) antagonists reduced, per se, the late hyperalgesic phase. Intra-periaqueductal grey perfusion with misoprostol increased periaqueductal grey glutamate, whereas it produced an increase followed by a decrease in GABA. Likewise, formalin increased glutamate and produced a biphasic response on GABA. When misoprostol was perfused in combination with the peripheral injection of formalin, we observed an increase of glutamate and an increase followed by a stronger decrease in GABA release. These data show that periaqueductal grey prostaglandin receptor stimulation increased formalin-induced nociceptive response in the late phase by increasing glutamate release and by producing a biphasic change in GABA release.

• Authors: Patrizia Oliva, Liberato Berrino, Vito de Novellis, Enza Palazzo, Ida Marabese, Dario Siniscalco, Mariantonietta Scafuro, Loredana Mariani, Francesco Rossi, Sabatino Maione
• Journal: European journal of pharmacology (Eur J Pharmacol) Vol. 530 Issue 1-2 Pg. 40-7 (Jan 13 2006) ISSN: 0014-2999 [Print] Netherlands
• PMID: 16360148 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Acetates
• Acrylamides
• Benzyl Compounds
• L-161982
• L-335677
• L-826266
• Naphthalenes
• Prostaglandin Antagonists
• Receptors, Prostaglandin E
• Thiophenes
• Triazoles
• Xanthones
• Misoprostol
• Formaldehyde
• 6-isopropoxy-9-oxoxanthene-2-carboxylic acid
• Glutamic Acid
• gamma-Aminobutyric Acid
• Dimethyl Sulfoxide

Topics

• Acetates (pharmacology)
• Acrylamides (pharmacology)
• Animals
• Benzyl Compounds (pharmacology)
• Dimethyl Sulfoxide (administration & dosage, toxicity)
• Extracellular Fluid (drug effects, metabolism)
• Formaldehyde
• Glutamic Acid (metabolism)
• Hyperalgesia (chemically induced, metabolism, physiopathology)
• Injections, Intraventricular
• Male
• Mice
• Microdialysis
• Misoprostol (administration & dosage, toxicity)
• Naphthalenes (pharmacology)
• Pain Measurement (methods)
• Periaqueductal Gray (drug effects, metabolism, physiopathology)
• Prostaglandin Antagonists (pharmacology)
• Receptors, Prostaglandin E (antagonists & inhibitors, physiology)
• Thiophenes (pharmacology)
• Triazoles (pharmacology)
• Xanthones (pharmacology)
• gamma-Aminobutyric Acid (metabolism)