Live imaging of altered period1 expression in the suprachiasmatic nuclei of Vipr2-/- mice.

Hughes AT, Guilding C, Lennox L, Samuels RE, McMahon DG, Piggins HD
J Neurochem. 2008 106 (4): 1646-57

PMID: 18554318 · PMCID: PMC2658715 · DOI:10.1111/j.1471-4159.2008.05520.x

Vasoactive intestinal polypeptide and its receptor, VPAC(2), play important roles in the functioning of the brain's circadian clock in the suprachiasmatic nuclei (SCN). Mice lacking VPAC(2) receptors (Vipr2(-/-)) show altered circadian rhythms in locomotor behavior, neuronal firing rate, and clock gene expression, however, the nature of molecular oscillations in individual cells is unclear. Here, we used real-time confocal imaging of a destabilized green fluorescent protein (GFP) reporter to track the expression of the core clock gene Per1 in live SCN-containing brain slices from wild-type (WT) and Vipr2(-/-) mice. Rhythms in Per1-driven GFP were detected in WT and Vipr2(-/-) cells, though a significantly lower number and proportion of cells in Vipr2(-/-) slices expressed detectable rhythms. Further, Vipr2(-/-) cells expressed significantly lower amplitude oscillations than WT cells. Within each slice, the phases of WT cells were synchronized whereas cells in Vipr2(-/-) slices were poorly synchronized. Most GFP-expressing cells, from both genotypes, expressed neither vasopressin nor vasoactive intestinal polypeptide. Pharmacological blockade of VPAC(2) receptors in WT SCN slices partially mimicked the Vipr2(-/-) phenotype. These data demonstrate that intercellular communication via the VPAC(2) receptor is important for SCN neurons to sustain robust, synchronous oscillations in clock gene expression.

MeSH Terms (14)

Animals Cells, Cultured Eye Proteins Female Gene Expression Regulation Male Mice Mice, Knockout Mice, Transgenic Microscopy, Confocal Motor Activity Period Circadian Proteins Receptors, Vasoactive Intestinal Peptide, Type II Suprachiasmatic Nucleus

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