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Spectra Undergraduate Research Journal

Category

Health & Natural Sciences & Engineering > Health Sciences > Psychology

Received

April 1, 2021

Accepted

July 19, 2021

Published

August 13, 2021

Authors

Dylone C. Braganza (DCB)1*, Emmanuel Flores (EF)2, Lauren A. Crew (LAC)2, Ryan A. Wirt (RAW)2, Andrew A. Ortiz (AAO)3, Adam M. McNeela (AMM)2, Jefferson W. Kinney(JWK)3, and James M. Hyman (JMH)2

Author Affiliations

1School of Life Sciences, University of Nevada, Las Vegas.

2Department of Psychology, University of Nevada, Las Vegas.

3Department of Brain Health, University of Nevada, Las Vegas.

Corresponding Author

*Dylone C. Braganza, bragad1@unlv.nevada.edu

Author Contributions

DCB: Wrote and revised the manuscript.

EF: Collected data

LAC: Collected data, analyzed the electrophysiological and behavioral data, and wrote and revised the manuscript.

RAW: Collected data, analyzed the electrophysiological and behavioral data, and wrote and revised the manuscript.

AAO: Collected data, analyzed the protein assays, and wrote and revised the manuscript

AMM: Collected data

JWK: Analyzed the protein assays, designed the experiment and provided funding support, and wrote and revised the manuscript.

JMH: Analyzed electrophysiological and behavioral data, designed the experiment and provided funding support, and wrote and revised the manuscript.

Conflicts of Interest

The electrophysiological and behavioral data that support the findings of this study are available by request from the corresponding author.

Ethical Considerations

The authors declare no competing interests.

Funding

Research reported in this publication was supported by the National Institute on Aging of the National Institutes of Health under Award Number R56AG062762. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Abstract

Alzheimer’s disease (AD) degrades the brain’s ability to remember, think, and carry out tasks. The exact cause is not known, but several risk factors have been identified, including diabetes mellitus (DM). DM causes elevated blood sugar levels due to reduced insulin production in the pancreas. The linkage between elevated glucose levels and the behavioral impairments are not fully understood, which was the focus of this study. Rats were trained to alternate directions in a maze to receive a reward on consecutive trials. After training, five rats were injected with streptozotocin (STZ), which induces hyperglycemia by injuring pancreatic beta cells. Three control animals received benign vehicle injections. All eight rats then underwent implant surgery and received an implant with 128 recording probes attached to an electronic interface board. The recording electrodes targeted the hippocampus and the anterior cingulate cortex (ACC), which are both associated with learning and memory processes. We found that STZ rats had reduced accuracy after long delay periods compared to the control rats. During task performance, there was a decrease in the power of theta activity and an increase in delta activity moments before starting a new trial. This was the opposite of control animals, who before starting new trials had higher theta power and less delta power as they focused. These findings imply that the STZ rats were impaired on longer delay periods. These findings are like reports from animal models of AD and may help explain why DM is a risk factor for AD.

Keywords

Alzheimer’s disease, diabetes mellitus, streptozotocin, learning, memory, working memory, anterior cingulate cortex, hippocampus

Submission Type

Primary research article

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