The Preliminary Study On The Mechanism Of Hypoalgesia Induced By Blocking Prostaglandin Synthesis In Inflammatory Pain Rat

Prostaglandin is one of the inflammatory factors which produced in the inflammatory tissue. It is generated from the action of cyclooxygenase.Prostaglandin can result in hyperalgesia through activating peripheral nociceptors. Cyclooxygenase exist two isoenzymes:one is cyclooxygenase-1which is produced in each type of normal tissue; and the other is cyclooxygenase-2which induced by the injury tissue or cytokines. Endogenous opioid peptides are bioactive peptides synthesized in mammal bodies.They exert analgesic and anti-nociceptive effect via binding to opioid receptors. This study used qRT-PCR experimental methods to investigate the expression of μ-opioid receptor, CGRP and IL-1β mRNA in the related tissue in hypoalgesia rats induced by blocking the synthesis of prostaglandin to illuminate the mechanism of the hypoalgesia. Results show that, when indomethacin was i.pl1h after carrageenan injected the expression of μ-opioid receptor mRNA was significantly increased in the spinal cord and the plantar subcutaneous tissuein indomethacin group compared with carrageenan group48h after carrageenan was injected i.pl., and the expression ofCGRP and IL-1β mRNA were significantly down-regulation in the plantar subcutaneous inflammation tissue,DRG,spinal cord in indomethacin group compared with carrageenan group in the same time.The study suggests that blocking prostaglandin synthesis could induce the up-release of endogenous opioid peptide and the up-regulate in the expression of μ-opioid receptor.These could restrain the expression of CGRP and IL-1β and generate analgesic effect This provides an evidence clarifing to illuminate the mechanism of hypoalgesia.