Pilocarpine-induced reciprocal hindlimb scratching in mice.
Intrathecal (IT) administration of pilocarpine (0.25-2.0 micrograms) to mice produced a vigorous and dose-related reciprocal hindlimb scratching response that lasted for 10-15 minutes. Neither the intracerebroventricular administration of pilocarpine at up to 10 times the intrathecal ED90 dose nor the subcutaneous administration of 10 mg/kg pilocarpine caused as robust an effect as IT administration. The reciprocal hindlimb scratching produced by the ED90 dose of pilocarpine (2 micrograms, IT) was antagonized in a dose-related manner by simultaneous IT administration of atropine (ID50 = 0.002 micrograms), methysergide (ID50 = 1.89 micrograms), the substance P antagonist [D-Pro2,D-Trp7,9]-SP (ID50 = 4.94 micrograms), and the putative neurokinin B antagonist [D-Pro2,D-Trp6,8,Nle10]-NK (ID50 = 3.33 micrograms), but not by yohimbine (5 micrograms), phentolamine (2 micrograms), or naloxone (2.5 micrograms). These results suggest that pilocarpine-induced reciprocal hindlimb scratching is mediated spinally, that the effect is produced by an action of pilocarpine on muscarinic receptors in the spinal cord, and that neurokinin, and perhaps 5-HT, mechanisms might also be involved.
D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D015287:Neurokinin B / Q000031:analogs & derivatives*; D009479:Neuropeptides / Q000494:pharmacology; D010446:Peptide Fragments; D010646:Phentolamine / Q000494:pharmacology; D010862:Pilocarpine / Q000008:administration & dosage / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D009479:Neuropeptides; D010446:Peptide Fragments; D010862:Pilocarpine; C050787:neurokinin B, Pro(2)-Trp(6,8)-Nle(10)-; D015016:Yohimbine; D013373:Substance P; D009270:Naloxone; C032132:substance P, prolyl(2)-tryptophan(7,9)-; D015287:Neurokinin B; D008784:Methysergide; D010646:Phentolamine