| Literature DB >> 12466222 |
Shinobu Sakurada1, Hiroyuki Watanabe, Takafumi Hayashi, Masayuki Yuhki, Tsutomu Fujimura, Kimie Murayama, Chikai Sakurada, Tsukasa Sakurada.
Abstract
The antagonistic actions of D-Pro(2)-endomorphins on inhibition of the paw withdrawal response by endomorphins were studied in mice. D-Pro(2)-endomorphin-1 and D-Pro(2)-endomorphin-2, injected intrathecally (i.t.), had no significant effect on the nociceptive thermal threshold alone. When D-Pro(2)-endomorphin-1 (0.05-0.1 pmol) was injected simultaneously with i.t. endomorphin-1 (5.0 nmol) or endomorphin-2 (5.0 nmol), antinociception induced by endomoprhin-1 was reduced significantly, whereas endomorphin-2-induced antinociception was not affected by D-Pro(2)-endomorphin-1. Antinociception induced by i.t. endomorphin-2 (5.0 nmol) was reduced significantly by its analogue, D-Pro(2)-endomorphin-2 (100 pmol), but not by D-Pro(2)-endomorphin-1. D-Pro(2)-endomorphin-1. D-Pro(2)-endomorphin-1 also antagonized the antinociceptive effect of i.t. DAMGO, a mu-opioid receptor agonist, whereas D-Pro(2)-endomorphin-2 failed to reduce the effect of DAMGO. These results suggest that endomorphin analogues containing D-Pro(2) are able to discriminate the antinociceptive actions of mu(1)- and mu(2)-opioid receptor agonists at the spinal cord level.Entities:
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Year: 2002 PMID： 12466222 PMCID： PMC1573622 DOI： 10.1038/sj.bjp.0705047
Source DB: PubMed Journal: Br J Pharmacol ISSN： 0007-1188 Impact factor: 8.739