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

Neurosci Lett. 1988 Nov 11;93(2-3):300-6. doi: 10.1016/0304-3940(88)90099-7.


Intracellular recordings were made from rat dorsal raphe neurons in vitro. Baclofen (30 microM) and 5-carboxamidotryptamine (5-CT, 300 nM to 1 microM) 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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Baclofen / pharmacology*
  • Dose-Response Relationship, Drug
  • Glutamates / pharmacology*
  • Male
  • Membrane Potentials / drug effects
  • Neurons / drug effects*
  • Pertussis Toxin*
  • Raphe Nuclei / cytology*
  • Rats
  • Rats, Inbred Strains
  • Serotonin / analogs & derivatives*
  • Serotonin / pharmacology
  • Synaptic Membranes / drug effects*
  • Virulence Factors, Bordetella / pharmacology*


  • Glutamates
  • Virulence Factors, Bordetella
  • Serotonin
  • 5-carboxamidotryptamine
  • Pertussis Toxin
  • Baclofen