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Chazalon M, Dumas S, Bernard JF, Sahly I, Tronche F, de Kerchove d'Exaerde A, Hamon M, Adrien J, Fabre V, Bonnavion P. The GABAergic Gudden's dorsal tegmental nucleus: A new relay for serotonergic regulation of sleep-wake behavior in the mouse. Neuropharmacology 2018; 138:315-330. [PMID: 29908240 DOI: 10.1016/j.neuropharm.2018.06.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 05/28/2018] [Accepted: 06/10/2018] [Indexed: 11/17/2022]
Abstract
Serotonin (5-HT) neurons are involved in wake promotion and exert a strong inhibitory influence on rapid eye movement (REM) sleep. Such effects have been ascribed, at least in part to the action of 5-HT at post-synaptic 5-HT1A receptors (5-HT1AR) in the brainstem, a major wake/REM sleep regulatory center. However, the neuroanatomical substrate through which 5-HT1AR influence sleep remains elusive. We therefore investigated whether a brainstem structure containing a high density of 5-HT1AR mRNA, the GABAergic Gudden's dorsal tegmental nucleus (DTg), may contribute to 5-HT-mediated regulatory mechanisms of sleep-wake stages. We first found that bilateral lesions of the DTg promote wake at the expense of sleep. In addition, using local microinjections into the DTg in freely moving mice, we showed that local activation of 5-HT1AR by the prototypical agonist 8-OH-DPAT enhances wake and reduces deeply REM sleep duration. The specific involvement of 5-HT1AR in the latter effects was further demonstrated by ex vivo extracellular recordings showing that the selective 5-HT1AR antagonist WAY 100635 prevented DTg neuron inhibition by 8-OH-DPAT. We next found that GABAergic neurons of the ventral DTg exclusively targets glutamatergic neurons of the lateral mammillary nucleus (LM) in the posterior hypothalamus by means of anterograde and retrograde tracing techniques using cre driver mouse lines and a modified rabies virus. Altogether, our findings strongly support the idea that 5-HT-driven enhancement of wake results from 5-HT1AR-mediated inhibition of DTg GABAergic neurons that would in turn disinhibit glutamatergic neurons in the mammillary bodies. We therefore propose a Raphe→DTg→LM pathway as a novel regulatory circuit underlying 5-HT modulation of arousal.
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Affiliation(s)
- Marine Chazalon
- Laboratory of Neurophysiology, Université Libre de Bruxelles (ULB), ULB Neurosciences Institute, Brussels, Belgium
| | | | - Jean-François Bernard
- Sorbonne Paris Cité, Université Paris Descartes, Inserm, Centre de Psychiatrie et Neurosciences (CPN), 75014, Paris, France; Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Neuroscience Paris Seine (NPS), Institut de Biologie Paris Seine (IBPS), 75005, Paris, France
| | - Iman Sahly
- Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Neuroscience Paris Seine (NPS), Institut de Biologie Paris Seine (IBPS), 75005, Paris, France
| | - François Tronche
- Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Neuroscience Paris Seine (NPS), Institut de Biologie Paris Seine (IBPS), 75005, Paris, France
| | - Alban de Kerchove d'Exaerde
- Laboratory of Neurophysiology, Université Libre de Bruxelles (ULB), ULB Neurosciences Institute, Brussels, Belgium
| | - Michel Hamon
- Sorbonne Paris Cité, Université Paris Descartes, Inserm, Centre de Psychiatrie et Neurosciences (CPN), 75014, Paris, France; Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Neuroscience Paris Seine (NPS), Institut de Biologie Paris Seine (IBPS), 75005, Paris, France
| | - Joëlle Adrien
- Université Paris Descartes, VIFASOM, Hôtel-Dieu de Paris, 75004, Paris, France
| | - Véronique Fabre
- Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Neuroscience Paris Seine (NPS), Institut de Biologie Paris Seine (IBPS), 75005, Paris, France.
| | - Patricia Bonnavion
- Laboratory of Neurophysiology, Université Libre de Bruxelles (ULB), ULB Neurosciences Institute, Brussels, Belgium; Sorbonne Paris Cité, Université Paris Descartes, Inserm, Centre de Psychiatrie et Neurosciences (CPN), 75014, Paris, France.
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