A diversity of organisms is endowed with the ability to emit light; this phenomenon is called bioluminescence and occurs mainly in marine organisms. Among echinoderms, some ophiuroid species (Echinodermata, Ophiuroidea) do possess this amazing capability of light production and are used as a study model in our laboratory. The present work investigates nervous control mechanisms of light emission at different levels such as extrinsic and intrinsic controls in three ophiuroid species: Amphiura filiformis, Ophiopsila aranea and Ophiopsila californica. Results were obtained by mean of different techniques such as pharmacology, immunohistochemistry, microspectrofluorometry measurements and patch-clamp. It appears from this study that nervous control of luminescence in ophiuroids presents a high diversity at all levels (e.g. neurotransmitters, second messengers, ion channels). Two new neurotransmitters have been identified as being inductors of light production in A. filiformis (tryptamine/octopamine) and O. californica (tryptamine) but up to now, all potential transmitters tested have failed to trigger luminescence in O. aranea. Some common features have however been highlighted between the studied species as to say the Ca2+ dependence of light emission and the cAMP pathway involvement. Moreover, the hypothesis of an indirect nervous control has been suggested for the three studied species. Therefore, a model can be presented in which neurotransmitters or electrical synapses, depending on the species, could act on the relay cell which would in turn activate the luminous cell (= photocyte) and induce photogenesis.

De nouveaux enjeux émergent dans le domaine de la Santé en raison du vieillissement de la population et du développement inquiétant de la Maladie d’Alzheimer (MA). Chez le sujet sain ou pathologique, peu d’études ont porté sur le vieillissement du contrôle nerveux de la respiration, en dépit de son rôle crucial pour l’oxygénation du cerveau. Cette thèse présente des recherches translationnelles, réalisées chez la souris, pour étudier le vieillissement physiologique et pathologique du contrôle nerveux de la respiration. Chez des souris transgéniques, modèles reconnus de la MA et du syndrome de Rett, nous décrivons le développement de neuropathologies respiratoires graves, conduisant à un décès prématuré. Nous montrons pour la première fois qu’une tauopathie du tronc cérébral altère le fonctionnement des voies aériennes supérieures, la vocalisation et la respiration. De plus, nos travaux suggèrent un rôle délétère de l’anesthésie pour la MA et identifient des pistes thérapeutiques nouvelles. En conclusion, nos travaux chez la souris peuvent avoir des retombées particulièrement intéressantes notamment pour la MA. / New issues are emerging in the field of Health care due to ageing of the population and the alarming development of Alzheimer’s Disease (AD). In healthy or pathological living being, very few studies are dealing with the ageing of the respiratory nervous control, in spite of the crucial role of respiration for brain oxygenation. This thesis presents translational research performed in mice to examine the physiological and pathological ageing of the respiratory nervous control. In mice from two transgenic strains, recognized models for AD and Rett syndrome, we describe the development of drastic respiratory neuropathologies leading to premature death. In the AD mouse model, we show for the first time that brainstem tauopathy triggers dysfunctions of the upper airways, impairs vocalization and alters respiration and respiratory control. In addition, our work suggests a deleterious effect of anaesthesia for AD and identifies new therapeutic strategies. This mouse research could well contribute to significant improvements in AD care.