Live imaging of altered period1 expression in the suprachiasmatic nuclei of Vipr2-/- mice.
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.
Hughes
Alun T L
AT
Faculty of Life Sciences, University of Manchester, Manchester, UK.
Guilding
Clare
C
Lennox
Laura
L
Samuels
Rayna E
RE
McMahon
Douglas G
DG
Piggins
Hugh D
HD
D000818:Animals; D002478:Cells, Cultured; D005136:Eye Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000379:methods; D009043:Motor Activity / Q000502:physiology; D056950:Period Circadian Proteins; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000032:analysis / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000737:chemistry / Q000378:metabolism*
D005136:Eye Proteins; C539023:Per1 protein, mouse; D056950:Period Circadian Proteins; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; C495510:Vipr2 protein, mouse