The 5-HT1A agonist ipsapirone enhances EEG slow wave activity in human sleep and produces a power spectrum similar to 5-HT2 blockade

Neurosci Lett. 1996 May 3;209(1):41-4. doi: 10.1016/0304-3940(96)12607-0.


The REM sleep-suppressing effect of postsynaptic 5-HT1A stimulation has been well established. Here we investigate the effects of the 5-HT1A agonist ipsapirone (10 and 20 mg) on sleep EEG power spectra during non-REM sleep in nine healthy humans. At the lower dose, slow wave activity (SWA; EEG power in the delta (1-4.5 Hz) range) was significantly enhanced. At the higher dose, where side-effects occurred, the enhancement in SWA was not significant. The spectral profile was characterized by a bimodal increase of power in the lower delta and in the theta (5-8 Hz) frequencies, and by troughs at 4 Hz and at 11 Hz, a pattern compellingly similar to that reported for a 5-HT2 antagonist (seganserin). We propose that the spectral data following the lower ipsapirone dose reflect a net decrease of neuronal activity at 5-HT2 receptors, mediated through stimulation of somatodendritic autoreceptors in the raphe nuclei (presynaptic) and/or through stimulation of postsynaptic 5-HT1A receptors colocalized with 5-HT2 receptors. The spectral non-REM sleep EEG profile might be used to investigate central 5-HT function in humans.

Publication types

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

MeSH terms

  • Adult
  • Electroencephalography / drug effects*
  • Female
  • Humans
  • Male
  • Pyrimidines / pharmacology*
  • Receptors, Serotonin / physiology*
  • Receptors, Serotonin, 5-HT1
  • Reference Values
  • Serotonin Receptor Agonists / pharmacology*
  • Sleep / drug effects
  • Sleep / physiology*
  • Sleep Stages / drug effects
  • Sleep Stages / physiology
  • Sleep, REM / physiology


  • Pyrimidines
  • Receptors, Serotonin
  • Receptors, Serotonin, 5-HT1
  • Serotonin Receptor Agonists
  • ipsapirone