Since the 19th century, the emergence of model systems has helped researchers further understand cellular signaling pathways, identify potential drug targets, and conduct environmental toxicological studies. Exogenous chemicals, such as pollutants, drugs, and industrial chemicals, may affect brain biological processes and functions and eventually lead to neurological diseases. However, the brain is a complex and well-organized human organ, which is fundamentally different from any existing model system. Animal models may not be able to completely simulate the human brain in testing the neurotoxicity of environmental pollutants due to species differences. Human brain organoids, generated from human pluripotent stem cells, are emerging model systems for neurotoxicological research in line with the real situation of human body at the level of genome, transcriptome, and metabolome, and provide an effective platform for testing neurotoxicity of environmental toxins. We reviewed the latest development of brain organoids technology and its application in the evaluation of environmental neurotoxins, and provided new insights into the application of brain organoids in environmental neurotoxicology.

Objective: To investigate the effect of lead exposure before pregnancy on bone lead mobilization and bone microstructure in pregnant rats, so as to provide the evidence for illustrating the potential mechanisms of bone lead mobilization during pregnancy. Methods: Twenty-six weaning female specific pathogen-free (SPF) rats of the Wistar strain were randomly divided into the exposure group and the control group. Rats in the exposure group were given 0.05% lead acetate solution for weeks, while animals in the control group were given 0.05% sodium acetate solution. Then, rats in both groups were given distilled water. Following removal of lead exposure for 4 weeks, female rats were co-caged with healthy males at the same age until pregnancy. The blood, femur and tibia specimens were collected from female rats on days 3 (GD3), 10 (GD10) and 17 (GD17) at pregnancy, and the blood and bone lead levels were measured using inductively coupled plasma mass spectrometry (ICP-MS). The unilateral rat femur was scanned using micro-computed tomography (micro CT), and the microstructure changes of cortical and trabecular bones were investigated. The structural and morphological changes of rat femur were observed using hematoxylin-eosin (HE) staining. Results: During the study period, satisfactory mental status and activity and good coat glossiness were observed in female rats in both groups, and there was no significant difference in the increase of rat body weight between groups. The blood lead level at GD17 and bone lead levels at GD3, GD10 and GD17 were significantly higher in rats in the exposure group than in the control group (P<0.05), and the trabecular bone lead level was significantly lower in rats in the exposure group at GD17 than at GD10 (P=0.015). The trabecular bone lead level correlated negatively with blood lead level (r=-0.578, P=0.049), and bone lead contributed 26.8% to blood lead. The bone mass, trabecular number, thickness and density of female rat trabecular bones all reduced in the exposure group at GD17, with an increase in trabecular space, and the proportion of trabecular areas reduced by 27.34% in the exposure group relative to the control group (t=2.851, P=0.046). Conclusions Lead exposure before pregnancy promotes the release of lead from trabecular bones into blood and affects bone microstructure in rats. There is bone lead mobilization during late pregnancy.

Background Lead (Pb) exposure impairs cognitive functions of children. Whether Pb exposure in different developmental stages induces long-term cognitive impairment, and whether chelation therapy could mitigate the cognitive impairment is rarely reported. Objective This experiment is designed to investigate effects of Pb exposure and chelation therapy during different developmental stages (breastfeeding, weaning, and early puberty periods) on mouse short-term and long-term cognitive functions. Methods C57BL/6 male mice in breastfeeding period, weaning period, and early puberty period (postnatal day 2, 21, and 41; PND 2, PND 21, and PND 41, n=30, respectively) were randomly divided into control, Pb exposure, and Pb+dimercaptosuccinic acid (DMSA) treatment groups (n=10 in each group). The control groups received standard food and deionized water. The Pb exposure mice received standard food and free drinking water containing Pb acetate (0.1% for dams, and 0.05% for pups). After receiving Pb acetate for 19 d, the Pb+DMSA treatment groups were given 1 mmol·kg⁻¹·d⁻¹ DMSA for 6 d with gastric infusion. Whole blood Pb levels were measured after DMSA treatment on experimental day 25. The effects on short-term cognitive function were tested in the Morris Water Maze task by the analyses of escape latency on PND 75−79, as well as target quadrant time and times of platform-crossing on PND 80. Hippocampal long-term potentiation of field excitatory postsynaptic potential (fEPSP) of mice on PND 365 was induced to demonstrate the effects on long-term cognitive function. Results The blood Pb levels among the Pb, Pb+DMSA, and control groups were statistically different for each developmental stage (F_{breastfeeding period}=43.47, F_{weaning period}=228.6, F_{early period of puberty}=274.2, all P<0.001). Compared to the counterpart control groups, blood Pb levels of the pb exposure groups (386.4, 265.0, and 178.1 μg·L⁻¹ in breastfeeding period, weaning period, and early puberty period, respectively) were significantly higher for all stages. After the chelation therapy, the blood Pb significantly decreased for all stages (28.68, 47.29, and 20.93 μg·L⁻¹ in the three periods, respectively, all P<0.001) and the Pb levels of the mice exposed in the breastfeeding period decreased most (by 92.58%, 82.15%, and 88.25% in the three periods, respectively, P<0.01). In the water maze task, the mice exposed to Pb in the breastfeeding period had a gentler decrease in escape latency (from 54.20 s on day 1 to 30.54 s on day 5, by 43.65 % decrease) than the control group (from 32.44 s on day 1 to 15.20 s on day 5, by 53.14 % decrease) (P<0.01) and a significant decrease in target quadrant time (P<0.05). After the chelation therapy, the escape latency of the DMSA-treated mice in the breastfeeding period (from 40.94 s on day 1 to 20.87 s on day 5, by 48.99 % decrease) was steeper than that of the Pb-exposed mice (P<0.05). The differences in the escape latency, target quadrant time, and times of platform-crossing were not significant between the Pb-exposed mice and the control mice in the weaning period and early period of puberty (all P>0.05). After the chelation therapy, such differences were also not significant compared with before therapy. Due to the small sample size, data were merged for different developmental stages in the long-term potentiation test. The amplitudes of fEPSP induced in the control, Pb-exposed, and DMSA treatment groups were significantly different (F_groups=212.2, F_time=11.36. P<0.001). The average fEPSP amplitude induced in the last 10 min recorded in the hippocampal slices in the Pb exposure group was significantly lower than that in the control group (P<0.05). After the DMSA treatment, no significant differences were observed in the fEPSP amplitudes between the Pb exposure group and the DMSA treatment group (P>0.05). When observing the fEPSP data by developmental stages, the fEPSP amplitude in the breastfeeding Pb-exposure group was 27.2% lower than that of the breastfeeding control group, while such changes were not obvious in the weaning period or in the early period of puberty. The fEPSP amplitude in breastfeeding DMSA treatment group was 44.3% higher than that of the breastfeeding Pb exposure group, while such changes were not observed in the weaning period or in early period of puberty. Conclusion Pb exposure during different developmental stages, especially in breastfeeding period, could affect short-term and long-term cognitive functions of mice. The harmful effects may be partially reversed by DMSA chelation therapy, especially being treated in breastfeeding period.

Childhood obesity continues to be a public health concern worldwide, which seriously affects children′s health.In recent years, children have been generally exposed to low doses of antibiotics, and antibiotic problem has drawn international attention.Domestic and foreign researches show that antibiotic exposure in the early life of children is associated with childhood obesity risk, while its specific mechanism has not been completely clear.It is possible that antibiotics may lead to changes in the normal intestinal flora colonization of infants and young children and damage the early intestinal microflora, thus increasing the risk of childhood obesity, but further research is needed to confirm this causal mechanism.

Objective: To evaluate the effect of curcumin on the lead burden in lead-exposed rats, and to study whether curcumin can influence the lipid peroxidation caused by lead exposure. Methods: A total of 70 rats of 21-day-old rats were divided randomly to 7 groups, the control group was given normal diet and drinking water, the curcumin group was given curcumin only 1 month after normal drinking water being given; the other 5 lead-exposed groups were given 2 g/L of acetate lead in free drinking water for 1 month and then randomly divided into lead-exposed group, low, medium and high concentration curcumin groups and Dimercaptosuccinic acid(DMSA) group, relatively.Lead levels of lead-exposed rats were determined by using inductively coupled plasma mass spectrometry, and commercial kit was used to detect antioxidant enzymes, and glutathione related enzymes and lipid peroxides. Results: The lead concentrations in the blood, hippocampus, liver and kidney of lead-exposed group increased, the levels of each group were (221.76±12.59) μg/L, (1.10±0.11) μg/g, (1.40±0.12) μg/g, (8.26±0.47) μg/g, and (57.58±6.09) μg/g, respectively; compared with the lead-exposed group, the lead concentrations reduced in the blood, hippocampus, liver and kidney significantly (F=90.67, 39.07, 27.34, 86.04, all P=0.000) in the curcumin-treated group, while the effect of curcumin in the bones showed no significant difference between groups(F=5.65, P=0.230). Lead could significantly improve the level of lipid peroxides in the serum and hippocampus, and curcumin-treated groups could significantly reduce the level of lipid peroxidation(F=58.03, 19.25, 32.27, 24.83, all P=0.000) and (F=28.18, 33.71, 38.95, 32.11, all P=0.000); lead could also reduce the antioxidant enzyme activity in the serum and hippocampus; curcumin-treated groups could significantly increase the antioxidant enzyme activity (F=18.24, 78.65, all P=0.000) and (F=13.68, 17.04, all P=0.000), respectively.The concentration in the curcumin group was better than that of DMSA group (P<0.05). Conclusions Curcumin can downregulate the lead concentrations in the blood, hippocampus, liver and kidney and improve the activity of antioxidant enzymes, inhibit the oxidative stress induced by lead, and thus resist the lead-induced damage.

Objective To investigate the inhibitory effect of Allicin on the apoptosis of hippocampal neurons induced by lead in rats.Methods Sixty male Sprague-Dawley rats aged 3 weeks were randomly divided into 6 groups,10 rats in each group,which were low dose group(A-L),medium-dose group(A-M) and high dose (A-H) Allicin group and lead exposure group (Pb group),dimercaptosuccinic acid (DMSA) group and blank control group.The blank control group animals were treated with ultrapure water,and the other 5 groups received 1.0 g/L lead acetate aqueous solution instead of ultrapure water after 20 days and they were treated them with compounds by oral gavage.The doses of Allicin in group A-L,A-M group and A-H group were 2.7 mg/kg and 5.4 mg/kg,and 10.8 mg/kg,respectively.The DMSA dose was 10.8 mg/kg,and the Pb group was given 9 g/L saline.After the model was established,the rats were sacrificed to collect whole blood and hippocampus.Blood lead and tissue lead concentrations were measured,and the level of apoptosis in hippocampus was observed by TUNEL staining.The levels of cysteine-containing aspartate-specific proteases (caspase)-3,caspase-9,poly adenosine diphosphate-ribose polymerase (PARP) mRNA and caspase-3,caspase-9,PARP activated protein and cytochromes C distribution in the hippocampus cells were detected by using real-time quantitative PCR (qPCR),Western blot,and immunofluorescence staining.Results (1) Lead levels in the blood lead and hippocampus of rats in A-L group,A-M group and A-H group [(190.54±11.33) μg/L,(0.28 ±0.03) μg/L;(159.55 ±16.94) μg/L,(0.22 ±0.06) μg/L;(l16.62 ±8.85) μg/L,(0.19 ±0.01) μg/L] were lower than those in Pb group [(271.34 ±21.23) μg/L,(0.31 ±0.04) μg/L],and there were significant differences (all P ＜ 0.05).The blood lead and hippocampal lead levels in the DMSA group [(50.12 ± 7.44) μg/L,(0.15 ± 0.03) μg/L] were lower than those in the A-L group,A-M group and A-H group.(2) The results of TUNEL staining showed that the apoptosis levels of hippocampus in A-L group,A-M group and A-H group were lower than that in Pb group [(2.81 ±0.17)％,(2.08 ±0.28)％,(1.33 ±0.08)％ vs.(4.23 ±0.17)％],and there were significant differences (all P ＜ 0.05);the apoptosis level of hippocampus in the DMSA group [(2.63 ± 0.32) ％] was higher than that in the A-M group and the A-H group,which was lower than that in the Pb group.(3) qPCR results showed that the levels of caspase-3,caspase-9 and PARP mRNA in A-H group were down-regulated compared with Pb group (1.07 ± 0.05,1.02 ± 0.02,1.11 ± 0.02 vs.1.34 ± 0.02,1.26 ±0.05,1.93 ± 0.07).The differences were statistically significant (P ＜ 0.05).The expression levels of caspase-3 and PARP mRNA in A-L group and A-M group were down-regulated (1.21 ± 0.05,1.43 ± 0.12,1.16 ± 0.02,1.20 ± 0.06 vs.1.34 ± 0.02,1.93 ± 0.07),and there were significant differences (all P ＜ 0.05),and there was no significant change in caspase-9 mRNA;the mRNA levels of caspase-3,caspase-9 and PARP in A-H group (1.07 ± 0.05,1.02 ± 0.02,1.11 ± 0.02) were lower than those in DMSA group (1.14 ± 0.02,1.15 ± 0.08,1.32 ±0.05).(4) Western blot results:compared with Pb group,the expression levels of activated caspase-3,caspase-9 and PARP protein in A-H group were down-regulated (A-H group:0.44 ± 0.15,0.58 ± 0.25 and 0.31 ±0.19,0.23 ±0.07 vs.Pb group:0.69 ±0.13,0.72 ±0.22 and 0.55 ±0.21,0.43 ±0.10),the expression of activated caspase-9 protein in A-M group was lower than that in Pb group (A-M group:0.59 ±0.18 vs.Pb group:0.72 ± 0.22),and there were significant differences (all P ＜ 0.05);the expression of activated caspase-3 and RARP protein in A-H group was lower than that in DMSA group.(5) Fluorescence staining showed that the expression of cytochrome C in cytoplasm of A-L group,A-M group and A-H group were significantly lower than that of Pb group and DMSA group.Conclusion Allicin can inhibit the apoptosis of hippocampus cells in rats with lead poisoning through mitochondrial pathway.The effect of Allicin on apoptosis inhibition may be better than DMSA.

Objectives To explore the efficacy of CaNa2EDTA in the treatment of chronic moderate lead poisoning, so as to optimize the chelation therapy for lead poisoning in children. Methods The clinical data of 14 patients with chronic moderate lead poisoning treated with CaNa2EDTA for 3 consecutive courses of lead removal during September 2014 to December 2016 were analyzed retrospectively. Twenty-four hour urinary lead levels during hospitalization were analyzed. The changes of blood lead levels before treatment, 3 days, and 5 days after treatment were also analyzed. Results In the 14 children (4 males and 10 females) average age was 2.35±1.47 years. After treatment with CaNa2EDTA for 3 consecutive courses, the blood lead levels were decreased significantly in all the patients, and the blood lead levels at 3 days after treatment were 0.76, 0.77, 0.72 times those at 5 days after treatment respectively. The decrease of blood lead levels per unit of drug in the first 3 days of treatment were significantly higher than those in 5 days of treatment (P<0.05). The decrease of blood lead levels at 3 days after treatment was 0.65, 0.71, 0.70 times , those in 5 days' treatment respectively. The decrease of urine lead levels per unit of drug in the first 3 days of treatment were significantly higher than those in 5 days of treatment (P<0.05). Conclusions CaNa2EDTA has an obvious effect on removal of lead.The efficiency of lead removal in 3 days of treatment was higher than in 5 days of treatment. Thus, a course of treatment for 3 days may be an altenative for a course of 5 days.

Lead poisoning has become a big threat to public health in China. Traditional treatments usually use chelators to accelerate the excretion of lead by forming complex compounds with it. However, chelators exhibit side effects and have little therapeutic effect on lead-induced impairment so that better drugs are needed. As antioxidants are effective for the treatment of lead poisoning, with lasting effect and little side effect, they have been the focus of increasing studies. This review provides a detailed account of updates on the effects of antioxidant drugs in the therapy of lead poisoning, and of the progress in antioxidant activity of puerarin, quercetin, curcumin, allicin and melatonin in treatment of lead poisoning. To some extent, these five types of drugs can reduce lead poisoning by accelerating lead excretion and antioxidant, increase the body′s antioxidant enzyme activity, reduce oxidative stress and repair damage, which promises some clinical value.

Objective To assess the distribution of blood lead levels and the sources of lead exposure in children with lead poisoning,and thus to offer recommendations for clinical diagnosis and treatment of childhood lead poisoning.Methods The clinical data of 129 patients with lead poisoning was collected and analyzed at the Out-patient Department of Lead Poisoning Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine during Sep.2012 and Aug.2013 were collected and analyzed.All children were required to fill out theoutpatient questionnaire on heavy metal (including children's demographic data,growth assessment,frequency of hand-mouth behavior,and the behavior of washing hands before eating,dietary,sources of lead exposure,and the family environment,etc.).Other data of medical history,physical examinations (height,weight,growth and development) were also collected.Blood samples were collected to measure blood lead level by graphite furnace atomic absorption spectrometry.Results (1) The above 129 patients were from 14 provinces (municipalities and autonomous regions),including 64 cases in Zhejiang (49.6％),30 cases in Shanghai (23.0％),13 cases in Jiangsu (10.1％),6 cases in Jiangxi (4.7％),5 cases in Hebei (3.9％),2 cases in Anhui and Guangdong (1.6％) ;and 1 case in Fujian,Henan,Hunan,Jilin,Inner Mongolia,Heilongjiang and Shandong (0.8％),respectively.(2) In the patients,the blood lead level was 17.0-892.0 μg/L[(251.5 ±155.8) μg/L] and the median was 235.0 μg/L.(3)The mean age of the children was 4.3 years.Fifteen cases were less than 1 year old,and the mean blood lead level was (367.8 ± 137.7) μg/L.Thirty-seven cases were 1-3 years old children,and the mean blood lead level was (250.5 ± 116.3) μg/L.Fifty cases were 3-6 years old children,and the mean blood lead level was (237.7 ± 179.7) μg/L.Twenty-seven cases were over 6 years old,and the mean blood lead level was (213.9 ± 141.8) μg/L.(4) One hundred and eleven cases of the children could find the definite sources of lead exposure,mainly from industrial pollution (35.7％) and domestic pollution (64.3％).The blood lead levels in 18 cases were less than 100 μg/L,and their definite lead pollution source was not found.(5) Most of the children had the symptoms of inattention,hyperactivity,aggressive behavior,constipation and abdominal pain,and so on.(6)Logistic regression analysis of children with blood lead levels ≥ 235.0 μg/L showed that lead pollutants and age were the main risk factors for lead poisoning.Conclusions Industrial pollution are associated with higher blood lead levels among children aged 0-6 years old (occupying one-third of the pollutants).The younger children tend to have higher blood lead levels,and the data also suggest that greater attention should be paid to children who used red powder.

Objective To study the deficiency of serf-regulation in impulsivity children with attention deficit hyperactivity disorder(ADHD)based on both procedures of action and inhibitory control.The event related potentials(ERPs)component P3 in Go/NoGo tasks was analyzed.Methods There were 15 impulsive children with ADHD and15 normal children in control group.Their age was from seven years old to eleven years old.The Go/NoGo stimulate-response model was adopted in the ERPs test.The occurrence of Go and NoGo trials was equal probability(each of 50%).Results(1)The high impulsive children had slower Go-RTs(reaction times)in making correct response than normal children,tended to be faster of NoGo-RTs in making error response and had lower correct rate.(2)P3amplitudes in both control and ADHD children had the tendency of Go-P3 > NoGo-P3,especially significant at CPz and Pz in ADHD children,showed the trend of parietal central to parietal maximum and the frontal minimum,The NoGo-P3 amplitude of ADHD group was smaller especially significant at FCz and Cz,and tended to be smaller than control on left hemisphere.(3)NoGo-P3 is smaller in impulsive children with ADHD than normal children,most significant at FCz.(4)Brain maps showed that impulsive children with ADHD were lower activation significantly in the right frontal area.Conclusions The efficiency of ADHD in action is lower.The behavior regulation in impulsive children is limited.Go/NoGo-P3 reflects action processing and attention.The left parietal lobe to central area is engaged much more in action procedure and attention.This research shows the evidence of weakened parietal cortex and right frontal cortex in impulsive children with ADHD.