Date of Award

5-2020

Document Type

Thesis

Degree Name

Master of Arts (MA)

College/School

College of Humanities and Social Sciences

Department/Program

Psychology

Thesis Sponsor/Dissertation Chair/Project Chair

Alan Pehrson

Committee Member

Joshua Sandry

Committee Member

Peter Vietze

Abstract

Patients suffering from Major Depressive Disorder (MDD) have cognitive impairments that modern antidepressants are unable to treat. There is a large body of research linking glutamate receptors to both cognitive functions and MDD. The present study looks at one type of glutamate receptors, the metabotropic glutamate 5 (mGlu 5) receptor, and the effects of its stimulation on a cognitive task on male Long-Evans rats. The following two hypotheses were used: 1) Memory performance in the delayed non-match to odor task will be progressively impaired as the time between the information and retention trial increases, and 2) administering a mGlu5 positive allosteric modulator such as CDPPB will improve performance on the delayed non-match to odor task. First, a time delayed non-match to odor task (DNMTO) was tested to see if it could function as a test of short-term memory. Results indicated that an increase in inter-trial intervals significantly lowered accuracy in the task. This DNMTO task thus showed a more ethologically relevant working memory task than the commonly used visual-based tasks as rats have poor vision. Then the rats were dosed with 3-Cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB), a positive allosteric modulator for mGlu 5 receptors, to test for an improvement on the task. No significant differences were found between control or any dose (1, 3, or 10 mg/kg IP) in either accuracy, latency, distance or speed. However, large effect sizes were found which implies that there was not enough power due the low sample sizes caused by attrition. This study was part of a larger research project delving into different glutamate receptors and their impact on both cognitive function and MDD.

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