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The kappa-opioid agonist (+/-)-bremazocine elicits peripheral antinociception by activation of the L-arginine/nitric oxide/cyclic GMP pathway.

Abstract：

:In view of the scarce information about the analgesic mechanism of kappa-opioid receptor agonists, the objective of the present study was to determine whether nitric oxide (NO) is involved in the peripheral antinociception of bremazocine, a kappa-opioid receptor agonist. Three drugs all interfering with the L-arginine/NO/cyclic GMP pathway were tested using the rat paw model of carrageenan-induced (250 microg) hyperalgesia: (a) N(G)-nitro-L-arginine (a nonselective NO-synthase inhibitor), (b) methylene blue (a guanylate cyclase inhibitor), and (c) zaprinast (a cyclic GMP phosphodiesterase inhibitor). Intraplantar administration of bremazocine (20, 40 and 50 microg) caused a dose-dependent peripheral antihyperalgesia against carrageenan-induced hyperalgesia. The possibility of the higher dose of bremazocine (50 microg) having central or systemic effect was excluded since administration of the drug into the left paw did not elicit antinociception in the contralateral paw. However, when the dose of bremazocine was increased to 100 microg, a significant increase in the nociceptive threshold was observed, as measured in the hyperalgesic contralateral paw. Peripheral antihyperalgesia induced by bremazocine (50 microg) was significantly reduced in a dose-dependent manner when N(G)-nitro-L-arginine (6, 9, 12 and 25 microg) or methylene blue (250, 375 and 500 microg) was injected before. Previous treatment with 50 microg of zaprinast (which had no effect when administered alone) potentiated the antihyperalgesic effect of bremazocine (20 microg). Our data suggest that bremazocine elicits peripheral antinociception by activation of the L-arginine/NO/cyclic GMP pathway and that nitric oxide is an intermediary in this mechanism, forming cyclic GMP.

journal_name

Eur J Pharmacol

journal_title

European journal of pharmacology

authors

Amarante LH,Duarte ID

doi

10.1016/s0014-2999(02)02275-6

keywords:

subject

Has Abstract

pub_date

2002-11-01 00:00:00

pages

19-23

issue

eissn

0014-2999

issn

1879-0712

pii

S0014299902022756

journal_volume

454

pub_type

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The kappa-opioid agonist (+/-)-bremazocine elicits peripheral antinociception by activation of the L-arginine/nitric oxide/cyclic GMP pathway.