Attenuation of phase shifts to light by activity or neuropeptide Y: a time course study

Lall, Gurprit S. and Biello, Stephany M. (2002) Attenuation of phase shifts to light by activity or neuropeptide Y: a time course study. Brain Research , 957 (1). pp. 109-116. ISSN 0006-8993 . (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Circadian rhythms in mammals can be synchronised to photic and non-photic stimuli. Interactions between photic and behavioural stimuli were investigated during the late subjective night, 6 h after activity onset in Syrian hamsters (CT18). Light pulses of 130 lx for 15 min at this time resulted in phase advance shifts. Novel wheel exposure, for a period of 3 h, following photic stimulation was able to attenuate the phase advancing effects of light. A time delay of up to 60 min between photic and behavioural stimuli also resulted in significant attenuation of light-induced phase shifts (P<0.05). A 90-min interval between stimuli resulted in no significant attenuation. Novel wheel exposure mediates its effects via the intergeniculate leaflet, which conveys information to the SCN and utilises neuropeptide Y (NPY) as its primary neurotransmitter. Phase shifts to light pulses given at CT18 were attenuated by NPY administration. Neuropeptide Y injections up to 60 min post-light exposure significantly attenuated phase shifts by 50% on average. However a 90-min interval between light and NPY microinjection did not significantly affect light-induced phase shifts. These results confirm previous work indicating that novel wheel exposure and NPY administration can modulate light-induced phase shifts during the late night. Further, they show for the first time that the time course for this interaction is similar between wheel running and NPY. Most significantly, our work indicates that the time course in vivo in the late night is similar to that shown previously in vitro during the early night.

Item Type: Article
Uncontrolled keywords: Animals Circadian Rhythm/drug effects/*physiology Cricetinae Male Mesocricetus *Motor Activity/physiology Neuropeptide Y/administration & dosage/*physiology *Photic Stimulation Time Factors
Subjects: Q Science
R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
R Medicine
Q Science > QH Natural history > QH301 Biology
Q Science > QP Physiology (Living systems)
Divisions: Faculties > Science Technology and Medical Studies > Medway School of Pharmacy
Depositing User: Gurprit Lall
Date Deposited: 03 Oct 2008 15:21
Last Modified: 22 Apr 2014 15:25
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