| 研究実績の概要 |
In this first year, I aimed to investigate the effect of oral administration of polystyrene nanoplastics (PS-NPs) on brain functions and behaviors in rats. Five-week-old Sprague Dawley male rats were given 45 nm PS-NPs (Polysciences, Warrington, PA, USA) or sterile water by oral administration at doses 10 mg/kg or 50 mg/kg thrice per week for four weeks. At the age of 9-week-old, behavioral tests such as open field test (OFT), novel object recognition (NOR) test, elevated plus maze (EPM) test and nest construction (NC) test were performed. The hippocampus was collected to detect neuronal activity indicators, synaptic proteins, inflammatory cytokines, neurotrophic factors, glial markers using real-time RT-PCR and immunohistochemical analyses. Hight dose PS-NPs-exposed rats showed anxiety-like behavior and cognitive deficit. Neuronal activity indicators (cFos, early growth response 1), synaptic proteins (PSD-95, synaptophysin), neurotrophic factors (BDNF, NGF) were significantly lower whereas inflammatory cytokines (IL1-beta, TNF-alpha) and microglial marker (Iba1) were significantly higher in high dose PS-NPs-exposed rats. Our results indicate oral exposure to PS-NPs induced learning, memory impairment and anxiety-like behavior by altering neuron-glia-immune cells interaction at synaptic regions in the rat hippocampus.
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| 今後の研究の推進方策 |
In the second year, I have a plan to perform co-exposure of PS-NP and DE-SOA. Four-week-old Sprague-Dawley (SD) male rats will be purchased from Charles River Laboratories Japan, Inc., Japan. Male rats will be allocated to four different groups (n = 8 per group) as 1) the control group, 2) nanoplatsics (NPs) oral exposure group, 3) DE-SOA inhalation exposure group and 4) NPs + DE-SOA co-exposure group. At the age of five-week, the control group will be administered by sterile water, NPs group will be administered oral polystyrene NPs 10 mg/kg or 50 mg/kg thrice per week for four weeks, DE-SOA exposure group will be given 120 microg/m3 in whole-body exposure chamber, NPs + DE-SOA exposure group will be administered polystyrene 10 mg/kg or 50 mg/kg thrice per week for four weeks and DE-SOA (118 microg/m3) in whole-body exposure chamber. Food (a commercial CE-2 diet, CLEA Japan, Inc., Tokyo, Japan) and water were given ad libitum. Exposure period will be one month. After one month exposure, at the age of six-week, behavioral tests will be performed to detect cognitive behavior, anxiety behavior, social behavioral test using Any-maze software video-assisted tracking system (Muromachi Kikai Co. Ltd., Japan). After completion of behavioral tests, the hippocampus will be collected to detect neurological and immunological biomarkers in male rats using real-time RT-PCR and immunohistochemical analyses.
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