The effect of a peripheral block on inflammation-induced prostaglandin E2 and cyclooxygenase expression in rats.
BACKGROUND: Peripheral inflammatory pain is associated with an upregulation of spinal cord COX-2 (cyclooxygenase-2), with a subsequent increase in central prostaglandin E2 (PGE2) levels associated with the development of hyperalgesia. In this study, we evaluated the effect of bupivacaine administered via a nerve block or via a systemic route on the spinal expression of PGE2 and COX in a model of peripheral inflammation in rats. METHODS: All rats randomly received three injections: 1) a left subcutaneous hindpaw injection (0.2 mL with either carrageenan 2% w/v or saline), 2) a left sciatic block (0.2 mL with either bupivacaine 0.5% or saline), and 3) a systemic injection (subcutaneous interscapular with 0.2 mL with either bupivacaine 0.5% or saline). Local edema, thermal, and mechanical hyperalgesia as well as cerebrospinal fluid PGE2 concentration and COX-1 and COX-2 expression in the spinal cord in dorsal root ganglions were measured. RESULTS: We confirmed that a bupivacaine block attenuates hyperalgesia and local inflammation in a model of inflammatory pain. This effect was associated with an inhibition of the increase in COX-2 expression induced by peripheral inflammation in dorsal root ganglions and cord. The subsequent production of PGE2 in cerebrospinal fluid was also impaired. Systemic bupivacaine did not modify either the hyperalgesia and local inflammation or COX expression. CONCLUSION: These results constitute a key element strongly suggesting that local anesthetics act at a different level when administered systematically or via a nerve block.
T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T2 T3 T4 T5 T6 T7 T8 T9
CHEMICAL CHEMICAL GENE-Y GENE-N GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-N CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
bupivacaine prostaglandin E2 COX-2 COX COX COX-1 COX-2 COX-2 cyclooxygenase-2 cyclooxygenase PGE2 bupivacaine prostaglandin E2 PGE2 bupivacaine PGE2 bupivacaine bupivacaine PGE2