Neuropeptide Y, GABA and circadian phase shifts to photic stimuli

Lall, G.S. and Biello, S.M. (2003) Neuropeptide Y, GABA and circadian phase shifts to photic stimuli. Neuroscience, 120 (4). pp. 915-921. ISSN 0306-4522 (Print). (The full text of this publication is not available from this repository)

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Abstract

Circadian rhythms can be phase shifted by photic and non-photic stimuli. The circadian clock, anatomically defined as the suprachiasmatic nucleus (SCN), can be phase delayed by light during the early subjective night and phase advanced during the late subjective night. Non-photic stimuli reset the clock when presented during the subjective day. A possible pathway for the non-photic resetting of the clock is thought to originate from the intergeniculate leaflet, which conveys information to the SCN through the geniculohypothalamic tract and utilizes among others neuropeptide Y (NPY) and GABA as neurotransmitters. Photic and non-photic stimuli have been shown to interact during the early and late subjective night. Microinjections of NPY or muscimol, a GABA(A) receptor agonist, into the region of the SCN can attenuate light-induced phase shifts during the early and late subjective night. The precise mechanism for these interactions is unknown. In the current study we investigate the involvement of a GABAergic mechanism in the interaction between NPY and light during the early and late subjective night. Microinjections of NPY significantly attenuated light-induced phase delays and inhibited phase advances (P<0.05). The administration of bicuculline during light exposure, before NPY microinjection did not alter the ability of NPY to attenuate light-induced phase delays and block photic phase advances. These results indicate that NPY attenuates photic phase shifts via a mechanism independent of GABA(A) receptor activation. Furthermore it is evident that NPY influences circadian clock function via differing cellular pathways over the course of a circadian cycle.

Item Type: Article
Uncontrolled keywords: Animals Bicuculline/pharmacology Circadian Rhythm/drug effects/*physiology Cricetinae Drug Administration Schedule/veterinary Drug Interactions GABA Antagonists/pharmacology Male Microinjections Neuropeptide Y/*pharmacology *Photic Stimulation Reaction Time/drug effects Suprachiasmatic Nucleus/drug effects Time Factors gamma-Aminobutyric Acid/*metabolism
Subjects: Q Science
R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
R Medicine
Q Science > QP Physiology (Living systems)
Divisions: Faculties > Science Technology and Medical Studies > Medway School of Pharmacy
Depositing User: Gurprit Lall
Date Deposited: 10 Sep 2008 11:55
Last Modified: 14 Jan 2010 14:31
Resource URI: http://kar.kent.ac.uk/id/eprint/8390 (The current URI for this page, for reference purposes)
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