Objective To explore the effects of exposure to atmospheric particulate matters on learning and memory functions in rats fed with high-fat and high-glucose diet.
Methods Healthy male SD rats (n=80) aged three weeks were randomized into four groups by weight. The exposure rats were exposed to atmospheric particulate matters in individually ventilated chambers, the control rats inhaled air filtered through highefficiency air filter, and both the control and exposure rats were divided into two groups including a high-fat and high-glucose diet group and a normal diet group. The animals were further divided into a 3-month and a 6-month sub-exposure categories with 10 rats in each subgroup. The abilities of learning and memory of rats were scored by Morris water maze test after the exposures.
Results In the orientation navigation test, after 3 months of exposure, the swimming distance and escape latency were (4.47±1.96) m and (26.89±10.37) s on training day 4 of the high-fat and high-glucose diet+atmospheric particulate matters exposure group, higher than those of the normal diet+filtered air group(2.13±1.38) m and (12.99±7.24) s and the high-fat and high-glucose diet+filtered air group(2.73±1.09) m and (15.01±4.43) s (P < 0.05); after 6 months of exposure, the swimming distance was (7.74±6.64) m on training day 4 of the high-fat and high-glucose diet+atmospheric particulate matters group, higher than that of the normal diet+filtered air group(3.68±2.11) m (P < 0.05), and no difference in escape latency was found among the four groups (P>0.05). In the spatial probe test, after the 3-month exposure, the count of traversing platform and target quadrant time were (2.30±0.48) and (31.41±5.48) s in the rats co-exposed to high-fat and high-glucose diet and atmospheric particulate matters, and (3.30±1.64) and (31.48±7.85) s in the rats treated with normal diet and atmospheric particulate matters; the two parameters in the two groups were lower than those of the normal diet+filtered air group(4.70±1.64) and (38.95±5.47) s (P < 0.05). The count of traversing platform of the rats co-exposed to high-fat and high-glucose diet and atmospheric particulate matters (2.40±1.51) was lower than that of the normal diet+filtered air group (4.00±1.05) after the 6-month exposure (P < 0.05).
Conclusion Combined exposure to atmospheric particulate matters and high-fat and high-glucose diet could induce more severe impairments in the learning and memory function of rats than single exposure.
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