title: Do nigro-striatal neurones possess a discrete dendritic modulatory mechanism? Electrophysiological evidence from the actions of amphetamine in brain slices.
abstract: Dopamine released from dendrites of nigrostriatal neurones in the substantia nigra exerts an inhibitory action on these cells. However, the spatio-temporal characteristics of the action of dendritic dopamine is still unclear. The aim of the present study was to investigate the responses of these neurones in the guinea-pig to amphetamine, applied locally in the region of the distal dendrites in pars reticulata. During intracellular recording in vitro it was found that amphetamine hyperpolarizes the membrane and causes a decrease in the input resistance, probably by increasing a potassium conductance. This response was resistant to blockade of sodium channels but sensitive to dopamine depletion by reserpine and alpha-methyl-p-tyrosine. The response showed tachyphylaxis and proved to be highly dependent on the site of administration of amphetamine. It is concluded that the release and action of dopamine occurs locally, in a heterogeneous pattern, within the dendritic field of nigrostriatal neurones. The possibility is discussed that this phenomenon underlies a modulatory mechanism, localized in dendrites.
authors.affiliation: University Department of Pharmacology, Oxford, U.K.
authors.forename: S
authors.initials: S
authors.lastname: Nedergaard
authors.forename: C
authors.initials: C
authors.lastname: Hopkins
authors.forename: S A
authors.initials: SA
authors.lastname: Greenfield
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D003712:Dendrites / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology*
chemical_list: D000662:Amphetamines; D004298:Dopamine