Involvement of opioid receptors in the antinociception produced by intracerebroventricularly administered spantide in mice.
The antinociceptive effect of intracerebroventricularly (i.c.v.) administered [D-Arg1, D-Trp7,9, Leu11]-substance P (spantide), a non-selective tachykinin antagonist, was examined using the mouse formalin test. Licking behaviour induced by 2% formalin solution in the hindpaw of mice had two peaks, 0-5 min (first phase) and 10-30 min (second phase). I.c.v. spantide produced a dose-dependent antinociception during the first and second phases. The ID50 values were 2.95 (1.59-5.46) nmol for the first phase and 2.87 (1.49-5.52) nmol for the second phase. The antinociceptive effect in the first phase, but not in the second phase produced by spantide was antagonized by pretreatment with naloxone (1.0 mg/kg, i.p.), an opioid receptor antagonist. An opioid binding study using [3H]naloxone revealed that spantide was able to inhibit [3H]naloxone binding to mouse brain membrane preparations. These results suggest that opioid receptor systems in the mouse brain are involved in spantide-induced antinociception during the first phase, but not during the second phase of the formalin-induced nociceptive behaviour.
Tan-No
K
K
Department of Pharmacology, Tohoku College of Pharmacy, Sendai, Japan.
Sakurada
T
T
Yamada
T
T
Sakurada
S
S
Kisara
K
K
D000595:Amino Acid Sequence; D000698:Analgesia; D000700:Analgesics / Q000008:administration & dosage*; D000818:Animals; D001921:Brain / Q000502:physiology; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D011957:Receptors, Opioid / Q000502:physiology*; D013373:Substance P / Q000008:administration & dosage / Q000031:analogs & derivatives*
D000700:Analgesics; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D013373:Substance P; D009270:Naloxone; C042867:spantide