A Combination of Environmental Enrichment and Nicotinamide After TBI in Juvenile Rats Leads to Transfer Effects in Cognitive Tasks

Author

Ryan Holden, Southern Illinois University CarbondaleFollow

Date of Award

5-1-2018

Degree Name

Master of Arts

Department

Psychology

First Advisor

Hylin, Michael

Abstract

AN ABSTRACT OF THE THESIS OF RYAN CHRISTOPHER HOLDEN, for the Master’s degree in Psychology, presented on March 30, 2018 at Southern Illinois University Carbondale. TITLE: A COMBINATION OF ENVIRONMENTAL ENRICHMENT AND NICOTINAMIDE AFTER TBI IN JUVENILE RATS LEADS TO TRANSFER EFFECTS IN COGNITIVE TASKS MAJOR PROFESSOR: Dr. Michael J. Hylin There are few effective therapeutic interventions that mediate behavioral deficits following damage for juvenile populations. Those that do succeed with positive initial outcomes fall short of long-term beneficial effects. Most of these regimens consist of monotherapy treatments; whereas, combinational therapeutics show more promise for rehabilitation. Utilization of a conjunctive behavioral and pharmacological treatment may provide a sustained effect even in the absence of the therapy. It may also maximize the therapeutic effectiveness of the individual treatments. This study used a combinational therapy that consisted of environmental enrichment (EE) and a 500mg/kg dose of nicotinamide (NAM) administered following a controlled cortical impact (CCI) injury on post-natal day 28 rats. After surgery, animals were divided into 6 groups: CCI+EE, CCI+NAM, CCI+NAM+EE, CCI+noEE+noNAM, sham+NAM, and sham+noEE+noNAM. Rats were tested on various motor (Foot Fault and Beam Walk) and cognitive tasks (Morris Water Maze and Radial Arm Maze). Results showed that the combinational therapy group performed similar to the sham groups in both motor tasks. There was also significant improvement in learning and memory as indicated by the water maze, with the latencies of the combined group being comparable to those of the uninjured sham groups. The positive effects demonstrated by the combination group also transferred to another cognitive task, the Radial Arm Maze, once EE treatment ceased. Specifically, the combinational therapy was significantly different from all other injured treatment groups making fewer reference and working memory errors. Overall, these findings point to the potential combined benefits of these two treatments and may further suggest that combinational therapeutics are an efficacious approach to a substantial, long-term functional recovery.