Differential antinociceptive effects of sendide, a NK1-receptor antagonist, and morphine in the capsaicin test.
The peptide NK1-receptor antagonists, sendide and [D-Trp7]sendide, have been evaluated for antinociceptive activity in the capsaicin test. Both peptides, injected intrathecally (i.t.) 5 min prior to intraplantar capsaicin, produced a dose-dependent reduction of the capsaicin-induced paw licking response. Naloxone (4.0 mg/kg) pretreatment did not affect sendide- and [D-Trp7]sendide-induced antinociception, whereas naloxone at a dose of 0.5 mg/kg antagonized the antinociceptive effect of i.t. administered morphine. Conversely, the antinociceptive action induced by both NK1-receptor antagonists was reduced significantly by i.t. co-administration of substance P. Morphine-induced antinociception was not antagonized by co-administration of substance P. These results led us to the understanding of differential action mechanism of NK1-receptor antagonist- and morphine-induced antinociception as assayed by the capsaicin test.
Sakurada
T
T
Department of Pharmacology, Tohoku College of Pharmacy, Sendai, Japan.
Yogo
H
H
Katsumata
K
K
Tan-No
K
K
Sakurada
S
S
Kisara
K
K
Ohba
M
M
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D002211:Capsaicin; D004305:Dose-Response Relationship, Drug; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D064729:Neurokinin-1 Receptor Antagonists; D010147:Pain Measurement / Q000187:drug effects; D010446:Peptide Fragments / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D013373:Substance P / Q000494:pharmacology*
D000700:Analgesics; D064729:Neurokinin-1 Receptor Antagonists; D010446:Peptide Fragments; C090191:tryptophyl(7)-sendide; D013373:Substance P; D009270:Naloxone; C032292:substance P (6-11); D009020:Morphine; D002211:Capsaicin; D011761:Pyrrolidonecarboxylic Acid