Psychogenetically selected (Roman high- and low-avoidance) rats differ in 24-hour sleep organization.
A comparison of sleep organization in Roman high-(RHA/Verh) and low-(RLA/Verh) avoidance rats, which differ in the way they respond to environmental stimuli and in several neuroendocrine and neurochemical parameters, was carried out. EEG-sleep recordings were obtained from adult males over 12:12 light-dark periods to determine how these two psychogenetically selected rat lines might also differ in their sleep-wake cycle. There was no significant difference in total sleep time between the two lines. However, the (hypoemotional) RHA/Verh rats showed an overall increase (percentage of total sleep) in paradoxical sleep (PS) duration, with a concomitant decrease in slow-wave sleep (SWS). During the dark phase, RHA/Verh rats showed a shorter PS latency and a larger number of PS episodes. Hourly sleep scoring also revealed a more discontinuous pattern (total sleep and PS vs. SWS) during the dark phase in RHA/Verh rats. In relation to recognized neurochemical and neuroendocrine differences between them, these rat lines may prove useful in investigations of the neurobiological mechanisms underlying sleep regulation.
Steimer
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Department of Psychiatry, University Hospital of Geneva, Chêne-Bourg, Switzerland.
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Driscoll
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de Saint Hilaire
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D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D005824:Genetics, Behavioral; D008027:Light; D008297:Male; D051381:Rats / Q000235:genetics* / Q000523:psychology*; D012641:Selection, Genetic; D012894:Sleep Stages / Q000502:physiology*