Neural Basis of Arousal Signaling for Non-Photic Resetting of the Circadian Clock

Moshirpour, Mahtab

Neural Basis of Arousal Signaling for Non-Photic Resetting of the Circadian Clock

dc.contributor.advisor	Antle, Michael Christopher
dc.contributor.author	Moshirpour, Mahtab
dc.contributor.committeemember	Dyck, Richard
dc.contributor.committeemember	Spanswick, Simon
dc.contributor.committeemember	Borgland, Stephanie
dc.contributor.committeemember	Mintz, Eric M.
dc.date	2023-11
dc.date.accessioned	2023-09-28T21:19:30Z
dc.date.available	2023-09-28T21:19:30Z
dc.date.issued	2023-09-21
dc.description.abstract	Input to the suprachiasmatic nucleus (SCN) from the intergeniculate leaflet (IGL) is necessary for non-photic entrainment. However, the underlying mechanisms of IGL activation remain unknown. There are several arousal centers in the brain that could be involved in bringing about non-photic entrainment. These include the lateral hypothalamus (LH) which contains clock-projecting orexin cells, and the cholinergic basal forebrain that directly communicates with the SCN. Even though arousal is the key component of non-photic entrainment, the relationship between the IGL and these arousal areas is unclear. We investigated the neural basis of arousal signaling by first studying the potential inputs to the IGL from the LH and the basal forebrain of Syrian hamsters. Projections to the IGL, from both the LH and the basal forebrain cholinergic cells were found. Next, we examined whether orexin is necessary and sufficient for non-photic phase shifting by both blocking orexin prior to an arousal-inducing protocol such as sleep deprivation and administering orexin in the IGL. It was found that orexin alone is not necessary or sufficient to cause shifts. Instead, it was found that dual administration of a glutamate receptor agonist with orexin is sufficient to cause significant shifts, suggesting an additive effect at the IGL. We next examined whether acetylcholine is necessary for non-photic entrainment. No attenuation of the arousal-induced response was observed by blocking acetylcholine at the IGL, suggesting that it is not necessary for non-photic entrainment, though it has been reported to be critical at the SCN level. Finally, accumulation of the sleep factor adenosine in the basal forebrain was mimicked as a potential signal for activating the basal forebrain. No significant phase shifts or cellular activation of the basal forebrain was observed after blocking adenosine at the basal forebrain. Taken together, the results present the first report of a dual role for orexin and glutamate in potentially gating the IGL’s non-photic inputs to the SCN.
dc.identifier.citation	Moshirpour, M. (2023). Neural basis of arousal signaling for non-photic resetting of the circadian clock (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/117274
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Circadian Rhythms
dc.subject	Circadian Clock
dc.subject	Neuroscience
dc.subject	Orexin
dc.subject	Glutamate
dc.subject	Acetylcholine
dc.subject	Adenosine
dc.subject.classification	Neuroscience
dc.subject.classification	Psychology--Experimental
dc.title	Neural Basis of Arousal Signaling for Non-Photic Resetting of the Circadian Clock
dc.type	doctoral thesis
thesis.degree.discipline	Psychology
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.