| Atmospheric particulate matter can accumulate in different parts of the human body,causing harm to health and causing diseases.Small particle size particles can also be transferred from the mother to the baby through the blood circulation and even the placenta,affecting the growth and development of the baby,resulting in cognitive and behavioral disorders.In order to explore the effect of continuous real-time atmospheric PM1 exposure during pregnancy and early childhood on the cognitive ability and brain heavy metal exposure load of offspring rats,the atmospheric particulate matter animal exposure platform was used,and the female rats were exposed to real-time PM1 from mating to the offspring rats.The rats were divided into control group,low,medium and high exposure groups.Water maze test was used to test the cognitive changes of offspring rats after they were exposed to 3weeks of age,and a group of rats were selected for death.The rest rats were tested again after they were exposed to 9 weeks of age,and were sampled after the end of the experiment.The PM1 concentration during the sampling period was analyzed by gravimetric method,and the concentration of metal elements in PM1,rat blood,hippocampus and frontal lobe tissue was determined by inductively coupled plasma mass spectrometry（ICP-MS）.The main results are as follows:（1）During the study period（December 22,2020 to March 23,2021）,the average PM1 concentration was 65.87 μg/m3,which was consistent with the trend of PM2.5 and PM10 concentrations in the same period.The outdoor temperature,dew point temperature and relative humidity of the sampling points were positively correlated with PM1 concentration（P<0.001）,while atmospheric pressure,average wind speed and horizontal visibility were negatively correlated with PM1.The metal elements in PM1 show a certain trend under the influence of polluted weather,and the top 6 concentrations are Al,Fe,K,Na,Mg and Ca.The source analysis results of enrichment factor method and principal component analysis showed that the pollutants mainly came from soil,coal combustion and traffic emissions.（2）Most of the metal elements in the whole blood of 3-week and 9-week-old offspring rats showed an upward trend with the exposure concentration gradient.The concentrations of most of the elements in the hippocampus of rats increased gradually,and most of the elements in the frontal lobes decreased gradually.increase and increase.In addition,the concentration of heavy metals in the blood and brain of female rats was higher than that of males.（3）During the exposure period,the body weight of the PM1 exposure group was higher than that of the control group at the age of 3 weeks,and there was no significant difference between the groups at the age of 9 weeks.The growth rate of male rats was higher than that of female rats.At the age of 3 weeks,the mass of the brain,uterus and ovary of the female rats in the exposure group decreased significantly,and the mass of the brain of the male rats decreased,and the tissue mass ratio（tissue weight/body weight）between males and females was close;The spleen,thymus,brain,heart,kidney,spleen,thymus,and epididymis of male rats decreased in mass,the tissue mass ratio between males and females was significantly different,and the brain mass ratio decreased significantly compared with 3 weeks of age.（4）The learning ability of the exposed group was hindered and decreased in a concentration gradient.The difference between the exposure group and the control group was more significant at 3 weeks of age;the latency period of the 9-week-old rats was shorter,and there was no significant difference.Female rats have higher latency than male rats.There was no significant difference in the spatial memory ability of the 3-week-old rats among the groups,and the spatial memory of the9-week-old rats was observed to be different between the control group and the high-concentration group.（5）The linear fitting changes between the metal elements accumulated in the breath of offspring rats and their blood and brain elements are consistent with the changes of element concentrations in the rat blood and brain tissue.There was a positive correlation between blood elements and frontal lobe elements in 3-week-old rats,and a negative correlation with hippocampal elements,and the correlation between blood and hippocampal elements was stronger in 9-week-old rats.The PCA results of blood and hippocampal and frontal elements in 3-week-old rats were significantly different between the control group and the high-concentration exposure group,while only the frontal elements in 9-week-old rats were significantly different between the control group and the high-concentration group.（6）The elements in the brain of rats have an effect on their cognitive ability.The frontal lobe elements had a stronger negative effect on the learning disability of the rats at the age of 3 weeks,and the hippocampus and frontal lobe elements had a stronger negative effect on the spatial memory ability.At the age of 9 weeks,the effects of hippocampal elements on the learning and memory ability of rats were enhanced.The OPLS-DA model had better fitting effect between the control group and the high-concentration group,and the differences were significant.The elements that had a negative effect on the cognitive ability of rats were mainly Zn,Cr,Ni and V. |
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