title: Evidence that the substantia nigra is a component of the endogenous pain suppression system in the rat.
abstract: The present study sought to determine whether opiate receptors in the substantia nigra may mediate antinociception produced by systemic morphine. Bilateral intranigral microinjection of naloxone-HCl (0.3-10 micrograms) suppressed the antinociceptive effects of systemically administered morphine sulfate (5 mg/kg, s.c.) on the tail-flick and hot-plate tests in a dose-related manner. Injection of naloxone (3 micrograms) into the ventral tegmental area did not alter antinociception produced by systemic morphine (5 mg/kg, s.c.). These findings support the argument that the substantia nigra is an essential, and previously unrecognized, component of the endogenous pain suppression system.
authors: Department of Psychology, Louisiana State University, Baton Rouge 70803.
authors: A A
authors: AA
authors: Baumeister
authors: T G
authors: TG
authors: Anticich
authors: M F
authors: MF
authors: Hawkins
authors: J C
authors: JC
authors: Liter
authors: H F
authors: HF
authors: Thibodeaux
authors: E C
authors: EC
authors: Guillory
mesh_terms: D000698:Analgesia; D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013378:Substantia Nigra / Q000502:physiology* / Q000503:physiopathology
chemical_list: D009270:Naloxone; D009020:Morphine