%0 Journal Article
%T PACAP ¨C Melatonin Interaction in Mouse Suprachiasmatic Nucleus Slice Cultures
%A Ehab TOUSSON
%J Journal of Neurological Sciences
%D 2010
%I Ege University Press
%X The pineal indoleamine-hormone melatonin elicits a wide variety of physiological actions across vertebrate species. Mouse suprachiasmatic nucleus (SCN) has high density of melatonin receptors that plays important role in the entrainment of the circadian pacemaker. SCN of the mammalian hypothalamus serves as the central biological clock, controlling circadian rhythms that are synchronized with the external light/dark cycle by retinal photoreception and transmission of light information via the retinohypothalamic tract (RHT). RHT has recently been shown to contain pituitary adenylate cyclase-activating polypeptide (PACAP) as neurotransmitter/neuromodulator. In the present study we cultured hypothalamic brain slices that included the region of the SCN on multi-microelectrode arrays to study in long-duration recordings simultaneously the electrical activity of SCN neurons and their possible target neurons in the hypothalamus. The extracellular recordings from the acute and   or organotypic hypothalamic slices mainly exhibited multi-unit activity often without the possibility to discriminate single unit activity. Application of melatonin (1nM for 50 min) at CT 10 shifted served the circadian rhythm in the firing rate and caused a phase-advance of 4 hours. Application of PACAP (100nM for 25 min) at CT6 evoked phase-advance of 2-3 hours while application of PACAP at CT10 had no effect on the circadian rhythm. Co-application of PACAP together with melatonin at CT 10 completely blocked the phase-advance normally induced by melatonin.
%K PACAP
%K melatonin
%K circadian rhythm
%K hypothalamic brain slices
%U http://www.jns.dergisi.org/pdf/pdf_JNS_380.pdf