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Title

Suprachiasmatic modulation of noradrenaline release in the ventrolateral preoptic nucleus

Authors
Jones, B. E.
Published in Journal of Neuroscience. 2007, vol. 27, no. 24, p. 6412-6416
Abstract As the major brain circadian pacemaker, the suprachiasmatic nucleus (SCN) is known to influence the timing of sleep and waking. We thus investigated here the effect of SCN stimulation on neurons of the ventrolateral preoptic nucleus (VLPO) thought to be involved in promoting sleep. Using an acute in vitro preparation of the rat anterior hypothalamus/preoptic area, we found that whereas single-pulse stimulations of the SCN evoked standard fast ionotropic IPSPs and EPSPs, train stimulations unexpectedly evoked a long-lasting inhibition (LLI). Such LLIs could also be evoked in VLPO neurons by pressure application of NMDA within the SCN, indicating the specific activation of SCN neurons. This LLI was shown to result from the presynaptic facilitation of noradrenaline release, because it was suppressed in presence of yohimbine, a selective antagonist of alpha2-adrenoreceptors. The LLI depended on the opening of a potassium conductance, because it was annulled at E(K) and could be reversed below E(K). These results show that the SCN can provide an LLI of the sleep-promoting VLPO neurons that could play a role in the circadian organization of the sleep-waking cycle.
Keywords Adrenergic alpha-Antagonists/pharmacologyAnimalsAnimals, NewbornBicuculline/pharmacologyDose-Response Relationship, DrugDose-Response Relationship, RadiationDrug InteractionsElectric Stimulation/methodsExcitatory Amino Acid Antagonists/pharmacologyGABA Antagonists/pharmacologyInhibitory Postsynaptic Potentials/drug effects/physiology/radiation effectsN-Methylaspartate/pharmacologyNeural Inhibition/drug effects/physiology/radiation effectsNeurons/drug effects/metabolismNorepinephrine/ metabolism/pharmacologyPatch-Clamp Techniques/methodsPreoptic Area/cytology/ metabolismQuinoxalines/pharmacologyRatsSuprachiasmatic Nucleus/ physiologyYohimbine/pharmacology
Stable URL http://archive-ouverte.unige.ch/unige:10430
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Other version: http://www.jneurosci.org/cgi/reprint/27/24/6412.pdf
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PMID: 17567801
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