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Published on: July 27, 2022
Exposure to polystyrene microplastics impairs hippocampus-dependent learning and memory in mice
Chiang-Wen Lee1, Lee-Fen Hsu2, I-Lin Wu3
1Department of Nursing, Division of Basic Medical Sciences, and Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Puzi City, Chiayi County 61363, Taiwan; Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Puzi City, Chiayi County 61363, Taiwan; Department of Safety Health and Environmental Engineering, Ming Chi University of Technology, New Taipei City 243303, Taiwan.
Abstract:
Microplastics (MPs) pollution has become a serious environmental issue worldwide, but its potential effects on health remain unknown. The administration of polystyrene MPs (PS-MPs) to mice for eight weeks impaired learning and memory behavior. PS-MPs were detected in the brain especially in the hippocampus of these mice. Concurrently, the hippocampus had decreased levels of immediate-early genes, aberrantly enhanced synaptic glutamate AMPA receptors, and elevated neuroinflammation, all of which are critical for synaptic plasticity and memory. Interestingly, ablation of the vagus nerve, a modulator of the gut-brain axis, improved the memory function of PS-MPs mice. These results indicate that exposure to PS-MPs in mice alters the expression of neuronal activity-dependent genes and synaptic proteins, and increases neuroinflammation in the hippocampus, subsequently causing behavioral changes through the vagus nerve-dependent pathway. Our findings shed light on the adverse impacts of PS-MPs on the brain and hippocampal learning and memory.
Insights
Polystyrene microplastics (PS-MPs) exposure impaired mouse learning and memory. This brain impact occurred via the vagus nerve, highlighting microplastic health risks.
Area of Science:
- Environmental Science
- Neuroscience
- Toxicology
Background:
- Microplastic (MP) pollution is a global concern with unknown health impacts.
- Polystyrene microplastics (PS-MPs) are common environmental contaminants.
Purpose of the Study:
- To investigate the effects of PS-MPs on learning, memory, and brain function in mice.
- To explore the role of the gut-brain axis, specifically the vagus nerve, in mediating these effects.
Main Methods:
- Mice were administered PS-MPs for eight weeks.
- Behavioral tests assessed learning and memory.
- Hippocampal tissue was analyzed for gene expression, synaptic proteins, and neuroinflammation.
- Vagus nerve ablation was performed in a subset of mice.
Main Results:
- PS-MP exposure impaired learning and memory in mice.
- PS-MPs were found in the brain, particularly the hippocampus.
- Hippocampal changes included decreased immediate-early genes, altered AMPA receptors, and increased neuroinflammation.
- Vagus nerve ablation ameliorated memory deficits in PS-MP exposed mice.
Conclusions:
- PS-MP exposure adversely affects brain function, specifically hippocampal learning and memory.
- The vagus nerve plays a crucial role in mediating the neurobehavioral effects of PS-MPs.
- Findings highlight potential neurological risks associated with microplastic pollution.
