Abstract

Vasoactive intestinal polypeptide (VIP) signaling is critical for circadian rhythms. For example, the expression of VIP and its main receptor, VPAC2R, is necessary for maintaining synchronous daily rhythms among neurons in the suprachiasmatic nucleus (SCN), a master circadian pacemaker in animals. Where and when VPAC2R protein is expressed in the SCN and other brain areas has not been examined. Using immunohistochemistry, we characterized a new antibody and found that VPAC2R was highly enriched in the SCN and detectable at low levels in many brain areas. Within the SCN, VPAC2R was circadian, peaking in the subjective morning, and abundantly expressed from the rostral to caudal margins with more in the dorsomedial than ventrolateral area. VPAC2R was found in nearly all SCN cells including neurons expressing either VIP or vasopressin (AVP). SCN neurons mainly expressed VPAC2R in their somata and dendrites, not axons. Finally, constant light increased VIP and AVP expression, but not VPAC2R. We conclude that the circadian clock, not the ambient light level, regulates VPAC2R protein localization. These results are consistent with VPAC2R playing a role in VIP signaling at all times of day, broadly throughout the brain and in all SCN cells.

Links

Publisher Full Text

Authors

An S, Tsai C, Ronecker J, Bayly A, Herzog ED

Institution

Department of Biology, Washington University, Saint Louis, Missouri 63130, USA.

Source

The Journal of comparative neurology 520:12 2012 Aug 15 pg 2730-41

MeSH

Animals
Cells, Cultured
Circadian Rhythm
Male
Mice
Mice, Inbred C57BL
Neurons
Organ Culture Techniques
Receptors, Vasoactive Intestinal Peptide, Type II
Signal Transduction
Suprachiasmatic Nucleus

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

22684939