Antidepressants and REM sleep in Wistar-Kyoto and Sprague-Dawley rats

Eur J Pharmacol. 2005 Oct 17;522(1-3):63-71. doi: 10.1016/j.ejphar.2005.08.050. Epub 2005 Oct 11.


Compared to other rat strains, the Wistar-Kyoto rats show increased amount of REM sleep, one of the characteristic sleep changes observed in depressed patients. The aims of this study were firstly to validate a simple sleep stage discriminator and then compare the effect of antidepressants on suppression of rapid eye movement (REM) sleep in Wistar-Kyoto rats and an outbred rat strain (Sprague-Dawley). Rats were implanted with telemetry transmitters with electroencephalogram/electromyogram electrodes. Following recovery, the animals were orally dosed at light onset with either desipramine (20 mg/kg), fluoxetine (10 mg/kg), citalopram (10 or 40 mg/kg) or vehicle in a cross-over design. Every 12-s epoch was automatically scored as WAKE, NREM or REM sleep. Results confirm that Wistar-Kyoto rats show increased amount of REM sleep and decreased REM latency compared with Sprague-Dawley rats. All antidepressants significantly suppressed REM sleep in Sprague-Dawley rats, but only the high dose of citalopram suppressed REM sleep in Wistar-Kyoto rats. These findings suggest that the enhanced REM activity in Wistar-Kyoto rats is less sensitive to the effect of antidepressants and therefore does not provide any additional predictive validity for assessing antidepressant efficacy.

Publication types

  • Comparative Study

MeSH terms

  • Administration, Oral
  • Animals
  • Antidepressive Agents / pharmacology*
  • Body Temperature / drug effects
  • Circadian Rhythm / physiology
  • Citalopram / pharmacology
  • Cross-Over Studies
  • Desipramine / pharmacology
  • Electroencephalography
  • Electromyography
  • Fluoxetine / pharmacology
  • Rats
  • Rats, Inbred WKY
  • Rats, Sprague-Dawley
  • Sleep, REM / drug effects*
  • Sleep, REM / physiology
  • Species Specificity


  • Antidepressive Agents
  • Fluoxetine
  • Citalopram
  • Desipramine