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Neuroanatomical Connections Between the Hypothalamus and the Suprachiasmatic Nucleus

Presenters Name: 
Rahul Patel
Primary Research Mentor: 
Ali Guler
Secondary Research Mentor: 
Qi Zhang
9:45 - 10:00
Time of Presentation: 
2019 - 9:45am to 10:00am
Commonwealth Room
Presentation Type: 
Presentations Academic Category: 
Grant Program Recipient: 
Harrison Undergraduate Research Grant

Introduction: The circadian system is responsible for maintaining an internal clock that is synchronized between every cell in the body. While the genetic mechanisms underlying the circadian system has been well understood, the neurological systems that allow for a coordinated system across cells in the body is still obscure. The Suprachiasmatic Nucleus (SCN) was identified through lesion studies as the bodies central pacemaker. While circadian rhythm is primarily synchronized through photic cues, the SCN may receive additional input from reward circuitry. Considering the location of the SCN in the hypothalamus, I hypothesize that the SCN forms neuroanatomical connections with nearby hypothalamic nuclei which control behaviors such as food intake, thermoregulation, and more. Methods: A stereotaxic surgery protocol was employed for injection of retrobead technology into the Arcuate Nucleus (ARC), which controls food intake behaviors. Retrobeads get absorbed at the axon terminal and retrogradely transported to the cell soma, allowing for visualization of neuronal inputs into the ARC. Two weeks after surgery, the brain is dissected, sectioned using a cryostat, and imaged for red staining indicative of the presence of the retrobeads. Results: While the results of these surgeries are pending, should retrobead staining be visualized in the SCN, this would be a novel discovery. Upon this finding, further research would be focused on elucidating the behavior of these neurons. Should staining not be found in the SCN, further research would be performed on the neuronal populations that did show staining from the ARC