title: Functional supersensitivity of alpha 1-adrenergic system in spinal ventral horn is due to absence of an uptake system and not to postsynaptic change.
abstract: The excitatory effects of adrenoceptor agonists on ventral horn cells were compared using an extracellular recording technique in spinal cord slices isolated from non-treated and 6-hydroxydopamine (6-OHDA)-treated rats (intracisternally 14 days previously). In spinal cord slices isolated from 6-OHDA-treated rats, the concentration-response curves for the alpha 1-adrenoceptor-mediated facilitatory effects produced by noradrenaline and phenylephrine but not those produced by methoxamine and isoproterenol were shifted to the left. 6-OHDA pretreatment decreased the level and uptake of noradrenaline and increased the number of [3H]prazosin binding sites in the spinal cord. These results suggest that in 6-OHDA-induced denervation, functional supersensitivity of the alpha 1-adrenergic system in the spinal ventral horn is due to absence of an uptake system, and not to postsynaptic change.
authors.affiliation: Department of Toxicology and Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hirayama
authors.forename: H
authors.initials: H
authors.lastname: Ono
authors.forename: H
authors.initials: H
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D000870:Anterior Horn Cells / Q000378:metabolism / Q000502:physiology*; D001679:Biogenic Amines / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003891:Desipramine / Q000494:pharmacology; D004558:Electric Stimulation; D004563:Electrochemistry; D006892:Hydroxydopamines / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D016627:Oxidopamine; D011224:Prazosin; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism / Q000502:physiology*
chemical_list: D001679:Biogenic Amines; D006892:Hydroxydopamines; D011942:Receptors, Adrenergic, alpha; D016627:Oxidopamine; D008729:Methoxamine; D007545:Isoproterenol; D003891:Desipramine; D009638:Norepinephrine; D011224:Prazosin