Altered sleep homeostasis after restraint stress in 5-HTT knock-out male mice: A role for hypocretins

Adeline Rachalski, Chloé Alexandre, Jean François Bernard, Françoise Saurini, Klaus Peter Lesch, Michel Hamon, Joëlle Adrien, Véronique Fabre

Research output: Contribution to journalArticlepeer-review

Abstract

Restraint stress produces changes in the sleep pattern that are mainly characterized by a delayed increase in rapid eye movement sleep (REMS) amounts. Because the serotonin (5-HT) and the hypocretin (hcrt) systems that regulate REMS are interconnected, we used mutant mice deficient in the 5-HT transporter (5-HTT-/-) to examine the role of 5-HT and hcrt neurotransmissions in the sleep response to stress. In contrast to wild-type mice, restraint stress did not induce a delayed increase in REMS amounts in 5-HTT-/- mice, indicating impaired sleep homeostasis in mutants. However, pharmacological blockade of the hcrt type 1 receptor (hcrt-R1) before restraint stress restored the REMS increase in 5-HTT-/- mice. In line with this finding, 5-HTT-/- mutants displayed after restraint stress higher long-lasting activation of hypothalamic preprohcrt neurons than wild-type mice and elevated levels of the hcrt-1 peptide and the hcrt-R1 mRNA in the anterior raphe area. Thus, hypocretinergic neurotransmission was enhanced by stress in 5-HTT -/- mice. Furthermore, in 5-HTT-/- but not wild-type mice, hypothalamic levels of the 5-HT metabolite 5-hydroxyindole acetic acid significantly increased after restraint stress, indicating a marked enhancement of serotonergic neurotransmission in mutants. Altogether, our data show that increased serotonergic-and in turn hypocretinergic-neurotransmissions exert an inhibitory influence on stress-induced delayed REMS. We propose that the direct interactions between hcrt neurons in the hypothalamus and 5-HT neurons in the anterior raphe nuclei account, at least in part, for the adaptive sleep-wakefulness regulations triggered by acute stress.

Original languageEnglish (US)
Pages (from-to)15575-15585
Number of pages11
JournalJournal of Neuroscience
Volume29
Issue number49
DOIs
StatePublished - Dec 9 2009
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)

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