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The impairment of learning and memory and synaptic loss in mouse after chronic nitrite exposure
Yongfang Chen1,2, Zhanjun Cui1, Lai Wang1
1Institute of Neurobiology, School of Nursing, Henan University, Kaifeng, 475004, People's Republic of China.
Abstract:
The objective of this study is to understand the impairment of learning and memory in mouse after chronic nitrite exposure. The animal model of nitrite exposure in mouse was created with the daily intubation of nitrite in adult healthy male mice for 3 months. Furthermore, the mouse's learning and memory abilities were tested with Morris water maze, and the expression of Synaptophysin and γ-Synuclein was visualized with immunocytochemistry and Western blot. Our results showed that nitrite exposure significantly prolonged the escape latency period (ELP) and decreased the values of the frequency across platform (FAP) as well as the accumulative time in target quadrant (ATITQ) compared to control, in dose-dependent manner. In addition, after nitrite exposure, synaptophysin (SYN) positive buttons in the visual cortex was reduced, in contrast the increase of γ-synuclein positive cells. The results above were supported by Western blot as well. We conclude that nitrite exposure could lead to a decline in mice's learning and memory. The overexpression of γ-synuclein contributed to the synaptic loss, which is most likely the cause of learning and memory impairment. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1720-1730, 2016.
Insights
Chronic nitrite exposure impairs learning and memory in mice. This study found that nitrite exposure reduced synaptic proteins and increased gamma-synuclein, leading to cognitive decline.
Area of Science:
- Neuroscience
- Toxicology
- Environmental Health
Background:
- Nitrite exposure is a potential environmental concern.
- Understanding its neurotoxic effects on cognitive functions is crucial.
Purpose of the Study:
- To investigate the impact of chronic nitrite exposure on learning and memory in a mouse model.
- To explore the underlying molecular mechanisms, specifically changes in synaptic protein expression.
Main Methods:
- Adult male mice were exposed to nitrite daily for 3 months.
- Learning and memory were assessed using the Morris water maze.
- Synaptophysin and gamma-synuclein expression were analyzed via immunocytochemistry and Western blot.
Main Results:
- Nitrite exposure dose-dependently prolonged escape latency and reduced memory performance in the Morris water maze.
- Reduced synaptophysin and increased gamma-synuclein expression were observed in the visual cortex.
- Western blot analysis confirmed these changes in protein expression.
Conclusions:
- Chronic nitrite exposure significantly impairs learning and memory in mice.
- Overexpression of gamma-synuclein contributes to synaptic loss, likely causing cognitive deficits.
- These findings highlight the neurotoxic potential of nitrites.
