Résumés
Résumé
Les progrès récents ont permis d’identifier les mécanismes moléculaires responsables de la genèse des rythmes circadiens. Le mécanisme par lequel ce signal circadien, une fois construit, est distribué dans l’organisme reste encore à déterminer. Chez les mammifères, si la transmission du signal par une libération rythmique de neurotransmetteurs à partir des voies nerveuses efférentes est partiellement démontrée, la réalité d’une transmission humorale restait à prouver. Cela vient d’être fait avec l’identification du TGF-α.
Summary
In mammals the suprachiasmatic nucleus (SCN) contains a clock that generate timing signals that drive daily rhythms. Enormous progress has recently been made in identifying the molecular mechanisms involved in the genesis of this circadian signal. An important question remains however regarding how the rhythmic signal from the biological clock is spread throughout the body. The clock appears to convey circadian signal throughout nervous and humoral factors. TGF-α has been recently identified has an humoral fracture involved in the daily control of locomotor activity. Precise connections between SCN neurons and SCN target areas however have been demonstrated to be essential for the control of most endocrine rhythms. The variety of neurotransmitters and neurotransmitters combination in the SCN projections, the differentially timed released of these transmitters in a restricted number of specific target areas explain how SCN acts.
Parties annexes
Références
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