Document Type
Article
Publication Date
1-1-1997
Publication Title
Journal of Neuroscience
Abstract
Mammalian circadian rhythms originate in the hypothalamic suprachiasmatic nuclei (SCN), from which rhythmic neural activity can be recorded in vitro. Application of neurochemicals can reset this rhythm. Here we determine cellular correlates of the phase-shifting properties of neuropeptide Y (NPY) on the hamster circadian clock in vitro. Drug or control treatments were applied to hypothalamic slices containing the SCN on the first day in vitro. The firing rates of individual cells were sampled on the second day in vitro. Control slices exhibited a peak in firing rate in the middle of the day. Microdrop application of NPY to the SCN phase advanced the time of peak firing rate. This phase-shifting effect of NPY was not altered by block of sodium channels with tetrodotoxin or block of calcium channels with cadmium and nickel, consistent with a direct postsynaptic site of action. Pretreatment with the glutamate receptor antagonists (DL-2-amino-5- phosphonovaleric acid and 6-cyano-7-nitroquinoxaline-2,3-dione disodium) also did not alter phase shifts to NPY. Blocking GABA(A) receptors with bicuculline (Bic) had effects only at very high (millimolar) doses of Bic, whereas blocking GABA(B) receptors did not alter effects of NPY. Phase shifts to NPY were blocked by pretreatment with inhibitors of protein kinase C (PKC), suggesting that PKC activation may be necessary for these effects. Bathing the slice in low Ca2+/high Mg2+ can block phase shifts to NPY, possibly via a depolarizing action. A depolarizing high K+ bath can also block NPY phase shifts. The results are consistent with direct action of NPY on pacemaker neurons, mediated through a signal transduction pathway that depends on activation of PKC.
Keywords
Calcium, Circadian, GABA, Glutamate, Hamster, Neuropeptide Y, Phase shift, PKC, Suprachiasmatic nucleus, TTX
Volume
17
Issue
21
First Page
8468
Last Page
8475
DOI
10.1523/jneurosci.17-21-08468.1997
ISSN
02706474
Recommended Citation
Biello, Stephany M.; Golombek, Diego A.; Schak, Kathryn M.; and Harrington, Mary E., "Circadian Phase Shifts to Neuropeptide Y in vitro: Cellular Communication and Signal Transduction" (1997). Psychology: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/psy_facpubs/106
Comments
Archived as published. Open access article.