Role of vasoactive intestinal peptide in the light input to the circadian system. (25th May 2015)

• Record Type: Journal Article
• Authors: Vosko, Andrew; van Diepen, Hester C.; Kuljis, Dika; Chiu, Andrew M.; Heyer, Djai; Terra, Huub; Carpenter, Ellen; Michel, Stephan; Meijer, Johanna H.; Colwell, Christopher S.
• Is Part Of: European journal of neuroscience. Volume 42:Number 2(2015:Jul.)
• Page Start: 1839
• Page End: 1848
• Publication Date: 2015-05-25
• Subjects: Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.12919
• Languages: English
• ISSNs: 0953-816X

Abstract

<abstract abstract-type="main" id="ejn12919-abs-0001"> <title>Abstract</title> <p>The neuropeptide vasoactive intestinal peptide (VIP) is expressed at high levels in a subset of neurons in the ventral region of the suprachiasmatic nucleus (SCN). While VIP is known to be important for the synchronization of the SCN network, the role of VIP in photic regulation of the circadian system has received less attention. In the present study, we found that the light‐evoked increase in electrical activity <italic>in vivo</italic> was unaltered by the loss of VIP. In the absence of VIP, the ventral SCN still exhibited <italic>N</italic>‐methyl‐<sc>d</sc>‐aspartate‐evoked responses in a brain slice preparation, although the absolute levels of neural activity before and after treatment were significantly reduced. Next, we used calcium imaging techniques to determine if the loss of VIP altered the calcium influx due to retinohypothalamic tract stimulation. The magnitude of the evoked calcium influx was not reduced in the ventral SCN, but did decline in the dorsal SCN regions. We examined the time course of the photic induction of <italic>Period1</italic> in the SCN using <italic>in situ</italic> hybridization in VIP‐mutant mice. We found that the initial induction of <italic>Period1</italic> was not reduced by the loss of this signaling peptide. However, the sustained increase in <italic>Period1</italic> expression (after 30 min) was significantly reduced. Similar results were found by measuring the light induction of cFOS in the SCN. These findings suggest that VIP is critical for longer‐term changes within the SCN circuit, but does not play a role in the acute light response.</p> </abstract>