title: Transsynaptic effect of an intrastriatal fetal nigral graft on the sensitivity of the substantia nigra pars reticulata to muscimol in the rat.
abstract: In the present study, we have investigated the effect of a unilateral 6-hydroxydopamine lesion of the nigrostriatal pathway and of a fetal nigral graft in the striatum on circling induced by unilateral microinjection of muscimol in a target structure of the striatum, the substantia nigra pars reticulata. A group of ovariectomized female rats received a unilateral nigral lesion with 6-hydroxydopamine. The lesioned animals were then tested for apomorphine circling (0.25 mg/kg sc). The animals which displayed circling with this drug were divided into two groups with equivalent circling rate. One group received a graft of 1.5 x 10(6) cells taken from the ventral mesencephalon of 14- to 15-day-old rat embryos and the other was kept as control. Six months after the graft, all animals received one microinjection on each side of the GABAergic agonist muscimol (25 ng/0.5 microliters) in site A (rostral part) or in site B (caudal part) of the substantia nigra pars reticulata using indwelling guide cannulae. Circling was monitored during 90 min after the injection. Our results show that: (1) Unilateral degeneration of the nigrostriatal pathway was associated with a decrease of contralateral rotation when muscimol was injected in site A (rostral part) and an increase when administrated in site B (caudal part) of the substantia nigra pars reticulata on the lesioned side compared to the intact side. (2) A fetal nigral graft implanted into the striatum can normalize the changes in GABAergic sensitivity in site A but not in site B of the substantia nigra pars reticulata.
authors.affiliation: Department of Pharmacology, Laval University, Québec, Canada.
authors.forename: D P
authors.initials: DP
authors.lastname: Gaudin
authors.forename: J A
authors.initials: JA
authors.lastname: St-Pierre
authors.forename: B
authors.initials: B
authors.lastname: Lavoie
authors.forename: P J
authors.initials: PJ
authors.lastname: Bédard
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D016380:Brain Tissue Transplantation / Q000502:physiology*; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D005260:Female; D016332:Fetal Tissue Transplantation / Q000502:physiology; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013239:Stereotyped Behavior / Q000187:drug effects / Q000502:physiology*; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology* / Q000637:transplantation; D013569:Synapses / Q000502:physiology*
chemical_list: D009118:Muscimol; D001058:Apomorphine