Behavioural characterization of substance P-induced nociceptive response in mice.
Intrathecal injection of substance P produced a behavioural syndrome, consisting of reciproacal hindlimb scratching and biting or fore- and hind-licking. Pretreatment with either an analogue of substance P, (D-Pro2, D-Trp7,9)-substance P (DPDT-SP) or (D-Arg1, D-Pro2,4, D-Trp7,9, Leu11)-substance P, given intrathecally, reduced the response to substance P in a dose-dependent manner. The behaviour induced by substance P was also inhibited by intrathecal, intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) injection of morphine. Intrathecal or subcutaneous injection of naloxone showed a biphasic effect on substance P response; the substance P-induced nociceptive response was increased by a small dose of naloxone, while it was inversely decreased by a large dose of naloxone. The results with analogues of substance P support the hypothesis that substance P, injected intrathecally, acts directly on substance P receptors in the spinal cord. The nociceptive response induced by substance P appears to be controlled by endogenous opioids in the spinal cord.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology*
D013373:Substance P; D009270:Naloxone; D009020:Morphine