Nocturnal expression of phosphorylated‐ERK1/2 in gastrin‐releasing peptide neurons of the rat suprachiasmatic nucleus

• DOI: 10.1111/j.1471-4159.2006.04416.x
• Publication Date: 2007-01-22T19:09:01Z
• Authors: Fabienne Guillaumond; Denis Becquet; Marie‐Pierre Blan...; Joan Attia; Mathias Moreno; Olivier Bosler; Anne‐Marie Franço...
• Keywords: Cell Nucleus; Male; Neurons; Cytoplasm; 0303 health sciences; Mitogen-Activated Protein Kinase 3; Light; [SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology; [SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology; Circadian Rhythm; Rats; Arginine Vasopressin; Rats, Sprague-Dawley; 03 medical and health sciences; Gastrin-Releasing Peptide; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Animals; Suprachiasmatic Nucleus; Phosphorylation; Vasoactive Intestinal Peptide

AbstractExtracellular regulated kinase (ERK) signalling is believed to play roles in various aspects of circadian clock mechanisms. In this study, we show in rat that the nuclear versus cytoplasmic intracellular distribution of the phosphorylated forms of ERK1/2 (P‐ERK1/2) in the central clock, namely the suprachiasmatic nucleus (SCN), is proportionally constant across the light/dark cycle while the spatial distribution and neurochemical phenotype of cells expressing these activated forms are time‐regulated according to a daily rhythm and light‐regulated. P‐ERK1/2 was exclusively found in neuronal elements. At daytime, it was detected throughout the dorsoventral extent of the SCN, partly within neurons synthesizing either arginine‐vasopressin or vasoactive intestinal peptide (VIP). At night time, it was segregated in the ventrolateral aspect of the nucleus, within a cluster of cells 45% of which were gastrin‐releasing peptide (GRP) neurons with or without co‐localization with VIP. After a light pulse at night, expression of P‐ERK1/2 increased in GRP neurons but also appeared in a population of neurons that stained for VIP only. These data show that the GRP neurons are closely associated with ERK1/2 activation at night and point to the importance of ERK1/2 signalling not only in intra‐SCN transmission of photic information but also in maintenance of neuronal rhythms in the SCN.