Neuropeptide y, gaba and circadian phase shifts to photic stimuli

Aug 21, 2003Neuroscience

How Neuropeptide Y and GABA Affect Body Clock Shifts in Response to Light

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Microinjections of neuropeptide Y (NPY) significantly attenuated light-induced phase delays and inhibited phase advances (P<0.05).

Circadian rhythms can be altered by both light and non-light stimuli at different times of the day.
The suprachiasmatic nucleus (SCN) is responsible for regulating these circadian rhythms.
NPY is suggested to play a role in resetting the circadian clock during light exposure.
Interactions between NPY and light occur during the early and late subjective night.
The mechanism by which NPY affects light-induced phase shifts operates independently of GABA(A) receptor activation.
NPY influences circadian clock function through different pathways depending on the time in the circadian cycle.

AI simplified

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.

Full Text

Full text is available at the source.

View full text (XML) ↗View full text ↗

Neuropeptide y, gaba and circadian phase shifts to photic stimuli

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief