Pertussis toxin pretreatment discriminates between pre- and postsynaptic actions of baclofen in rat dorsal raphe nucleus in vitro

William F. Colmers, John T. Williams

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Abstract

Intracellular recordings were made from rat dorsal raphe neurons in vitro. Baclofen (30 μM) and 5-carboxamidotryptamine (5-CT, 300 nM to 1 μM) hyperpolarized these neurons by 10 and 13 mV, respectively. Depolarizing synaptic potentials (DSPs) were evoked by single shocks: baclofen reduced the amplitude of the DSP by 81%, but 5-CT reduced it by only 23%. The somatic response to iontophoretically applied glutamate pulses was reduced by 12% by baclofen, and 23% by 5-CT. In slices from rats pretreated with intracerebroventricular pertussis toxin (PTX), the ability of baclofen to reduce the DSP was almost unchanged, although the hyperpolarizing action of baclofen, and both actions of 5-CT were virtually eliminated. We conclude that it is possible to distinguish the pre- and postsynaptic actions of baclofen with PTX, and that the actions of 5-CT are both blocked.

Original languageEnglish (US)
Pages (from-to)300-306
Number of pages7
JournalNeuroscience Letters
Volume93
Issue number2-3
DOIs
StatePublished - Nov 11 1988

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Keywords

  • Baclofen
  • Pertussis toxin
  • Presynaptic inhibition
  • Rat dorsal raphe nucleus
  • Serotonin
  • γ-Aminobutyric acid

ASJC Scopus subject areas

  • Neuroscience(all)

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