Article

Vasoactive intestinal polypeptide requires parallel changes in adenylate cyclase and phospholipase C to entrain circadian rhythms to a predictable phase.

Department of Biology, Washington University, St. Louis, MO 63130-4899, USA.
Journal of Neurophysiology (impact factor: 3.32). 03/2011; 105(5):2289-96. DOI:10.1152/jn.00966.2010 pp.2289-96
Source: PubMed

ABSTRACT Circadian oscillations in the suprachiasmatic nucleus (SCN) depend on transcriptional repression by Period (PER)1 and PER2 proteins within single cells and on vasoactive intestinal polypeptide (VIP) signaling between cells. Because VIP is released by SCN neurons in a circadian pattern, and, after photic stimulation, it has been suggested to play a role in the synchronization to environmental light cycles. It is not known, however, if or how VIP entrains circadian gene expression or behavior. Here, we tested candidate signaling pathways required for VIP-mediated entrainment of SCN rhythms. We found that single applications of VIP reset PER2 rhythms in a time- and dose-dependent manner that differed from light. Unlike VIP-mediated signaling in other cell types, simultaneous antagonism of adenylate cyclase and phospholipase C activities was required to block the VIP-induced phase shifts of SCN rhythms. Consistent with this, VIP rapidly increased intracellular cAMP in most SCN neurons. Critically, daily VIP treatment entrained PER2 rhythms to a predicted phase angle within several days, depending on the concentration of VIP and the interval between VIP applications. We conclude that VIP entrains circadian timing among SCN neurons through rapid and parallel changes in adenylate cyclase and phospholipase C activities.

0 0
 · 
0 Bookmarks
 · 
22 Views
  • Article: Circadian rhythms in isolated brain regions.
    Michikazu Abe, Erik D Herzog, Shin Yamazaki, Marty Straume, Hajime Tei, Yoshiyuki Sakaki, Michael Menaker, Gene D Block
    [show abstract] [hide abstract]
    ABSTRACT: The suprachiasmatic nucleus (SCN) of the mammalian hypothalamus has been referred to as the master circadian pacemaker that drives daily rhythms in behavior and physiology. There is, however, evidence for extra-SCN circadian oscillators. Neural tissues cultured from rats carrying the Per-luciferase transgene were used to monitor the intrinsic Per1 expression patterns in different brain areas and their response to changes in the light cycle. Although many Per-expressing brain areas were arrhythmic in culture, 14 of the 27 areas examined were rhythmic. The pineal and pituitary glands both expressed rhythms that persisted for >3 d in vitro, with peak expression during the subjective night. Nuclei in the olfactory bulb and the ventral hypothalamus expressed rhythmicity with peak expression at night, whereas other brain areas were either weakly rhythmic and peaked at night, or arrhythmic. After a 6 hr advance or delay in the light cycle, the pineal, paraventricular nucleus of the hypothalamus, and arcuate nucleus each adjusted the phase of their rhythmicity with different kinetics. Together, these results indicate that the brain contains multiple, damped circadian oscillators outside the SCN. The phasing of these oscillators to one another may play a critical role in coordinating brain activity and its adjustment to changes in the light cycle.
    Journal of Neuroscience 01/2002; 22(1):350-6. · 7.11 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

candidate signaling pathways
 
cell types
 
Circadian oscillations
 
circadian pattern
 
dose-dependent manner
 
environmental light cycles
 
intracellular cAMP
 
phospholipase C activities
 
SCN neurons
 
simultaneous antagonism
 
single cells
 
transcriptional repression
 
vasoactive intestinal polypeptide
 
VIP applications
 
VIP entrains circadian gene expression
 
VIP entrains circadian timing
 
VIP reset PER2 rhythms
 
VIP treatment entrained PER2 rhythms
 
VIP-induced phase shifts
 
VIP-mediated signaling
 

Sungwon An