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International Journal of Alzheimer’s Disease
Volume 2012 (2012), Article ID 732634, 10 pages
http://dx.doi.org/10.1155/2012/732634
Research Article

Dietary Cholesterol Concentration and Duration Degrade Long-Term Memory of Classical Conditioning of the Rabbit’s Nictitating Membrane Response

1Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV 26506, USA
2Department of Physiology and Pharmacology, West Virginia University, P.O. Box 9302, Morgantown, WV 26506, USA
3Department of Neurobiology and Anatomy, West Virginia University, Morgantown, WV 26506, USA

Received 11 January 2012; Accepted 7 February 2012

Academic Editor: Diana S. Woodruff-Pak

Copyright © 2012 Bernard G. Schreurs et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A rabbit model of Alzheimer’s disease based on feeding a cholesterol diet for eight weeks shows sixteen hallmarks of the disease, including learning and memory changes. Although we have shown 2% cholesterol and copper in water can retard learning, other studies show feeding dietary cholesterol before learning can improve acquisition whereas feeding cholesterol after learning can degrade long-term memory. We explored this issue by manipulating cholesterol concentration and duration following classical trace conditioning of the rabbit’s nictitating membrane response and assessed conditioned responding after eight weeks on cholesterol. First, rabbits given trace classical conditioning followed by 0.5%, 1%, or 2% cholesterol for eight weeks showed body weight and serum cholesterol levels that were a function of dietary cholesterol. Although all concentrations of cholesterol showed some sign of retarding long-term memory, the level of memory retardation was correlated with serum cholesterol levels. Second, rabbits given trace conditioning followed by different durations of a 2% cholesterol diet combined with different durations of a 0% control diet for 8 weeks showed duration and timing of a 2% cholesterol diet were important in affecting recall. The data support the idea that dietary cholesterol may retard long-term memory.