2021 年 38 巻 p. 7-13
Although Zinc (Zn) is an essential element, an excess amount of Zn is known to cause neurotoxic effects. The increased consumption of saturated fats in a westernized high-fat diet contributes to neurodegenerative disease and senile dementia. In our previous study, aged female mice were administered 0, 200, or 500 ppm Zn in drinking water for 30 weeks and subjected to Y-maze, novel object recognition, and step-through passive avoidance tests. Thirty-week exposure to Zn did not inhibit learning and memory in the Y-maze test, but was found to inhibit learning and memory in the novel object recognition and step-through passive avoidance tests in a dose-dependent manner. These results suggested that administration of excess Zn impaired long-term memory and object recognition memory in aged mice. As such, we studied whether a high-fat diet influences learning and memory deficits caused by chronic exposure to Zn in aged mice. The results of novel object recognition, step-through passive avoidance, and fear conditioning tests showed that high-fat diet feeding inhibited learning and memory in the step-through passive avoidance and fear conditioning tests but improved learning and memory in the novel object recognition test.