Electrophysiological and pharmacological characterization of serotonergic dorsal raphe neurons recorded extracellularly and intracellularly in rat brain slices

Brain Res. 1983 Dec 19;289(1-2):109-19. doi: 10.1016/0006-8993(83)90011-2.


Extracellular and intracellular recordings were made from dorsal raphe (DR) neurons in frontal rat brain slices maintained in vitro. A population of neurons was found which displayed electrophysiological and pharmacological characteristics of serotonin-containing DR neurons recorded in vivo. Recorded extracellularly, these neurons displayed biphasic or triphasic action potentials of 1.5-3.0 ms duration, and discharged with a slow and steady rhythm. Recorded intracellularly these neurons displayed action potentials of about 1.8 ms duration, which were followed by large (10-20 mV) after hyperpolarizations which normally lasted 200-800 ms. These presumed serotonergic DR neurons were inhibited by LSD and serotonin. They were excited by norepinephrine, or the alpha-agonist phenylephrine, and these activations could be reduced or blocked by alpha-adrenoreceptor antagonists including the selective alpha 1-antagonist, prazosin. The major difference between the in vitro recordings and previous in vivo recordings from anesthetized animals was a reduction in the number of spontaneously firing DR neurons. This was probably due, at least in part, to a disfacilitation of serotonergic DR neurons in the slice caused by the functional removal of a tonic noradrenergic input.

Publication types

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

MeSH terms

  • Adrenergic alpha-Antagonists / pharmacology
  • Animals
  • Brain Stem / physiology*
  • Culture Techniques
  • Dose-Response Relationship, Drug
  • Extracellular Space / physiology
  • Female
  • Intracellular Fluid / physiology
  • Male
  • Membrane Potentials / drug effects
  • Neurons / physiology
  • Norepinephrine / pharmacology
  • Phenylephrine / pharmacology
  • Raphe Nuclei / physiology*
  • Rats
  • Serotonin / metabolism*
  • Synaptic Transmission / drug effects


  • Adrenergic alpha-Antagonists
  • Phenylephrine
  • Serotonin
  • Norepinephrine