Enhanced zinc consumption causes memory deficits and increased brain levels of zinc

• Published in: Journal of non-crystalline solids 2005-01, Vol.83 (5), p.793-803
• Main Authors: Flinn, J.M., Hunter, D., Linkous, D.H., Lanzirotti, A., Smith, L.N., Brightwell, J., Jones, B.F.
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Aging - psychology; Animal; Animals; Atlantis platform; Biological and medical sciences; Biometals; BRAIN; Brain Chemistry - drug effects; Brain concentrations of zinc; Carbonates - pharmacology; Cognitive deficits; CONSUMPTION RATES; Drinking water; Female; Fundamental and applied biological sciences. Psychology; Learning; Learning. Memory; Male; Maze Learning - drug effects; Memory; Memory Disorders - chemically induced; Morris Water Maze; national synchrotron light source; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; Space Perception - drug effects; Spatial memory; Spectrometry, X-Ray Emission; Synchrotron X-ray fluorescence; Thigmotaxicity; Water; Working memory; ZINC; Zinc - pharmacokinetics; Zinc - pharmacology; Zinc Compounds - pharmacology
• ISSN: 0031-9384; 0022-3093; 1873-507X; 1873-4812
• DOI: 10.1016/j.physbeh.2004.10.009

Zinc deficiency has been shown to impair cognitive functioning, but little work has been done on the effects of elevated zinc. This research examined the effect on memory of raising Sprague–Dawley rats on enhanced levels of zinc (10 ppm ZnCO 3; 0.153 mM) in the drinking water for periods of 3 or 9 months, both pre- and postnatally. Controls were raised on lab water. Memory was tested in a series of Morris Water Maze (MWM) experiments, and zinc-treated rats were found to have impairments in both reference and working memory. They were significantly slower to find a stationary platform and showed greater thigmotaxicity, a measure of anxiety. On a working memory task, where the platform was moved each day, zinc-treated animals had longer latencies over both trials and days, swam further from the platform, and showed greater thigmotaxicity. On trials using an Atlantis platform, which remained in one place but was lowered on probe trials, the zinc-treated animals had significantly fewer platform crossings, spent less time in the target quadrant, and did not swim as close to the platform position. They had significantly greater latency on nonprobe trials. Microprobe synchrotron X-ray fluorescence (μSXRF) confirmed that brain zinc levels were increased by adding ZnCO 3 to the drinking water. These data show that long-term dietary administration of zinc can lead to impairments in cognitive function.