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- Title
Altered Sleep Homeostasis after Restraint Stress in 5-HTT Knock-Out Male Mice: A Role for Hypocretins.
- Authors
Rachalski, Adeline; Chloé Alexandre; Bernard, Jean-François; Saurini, Françoise; Lesch, Klaus-Peter; Hamon, Michel; Adrien, Joëlle; Fabre, Véronique
- 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.
- Subjects
HOMEOSTASIS; RAPID eye movement sleep; PHYSIOLOGICAL stress; SEROTONIN; OREXINS; NEURAL transmission
- Publication
Journal of Neuroscience, 2009, Vol 29, Issue 49, p15575
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.3138-09.2009