[Effect of dimethoate on primary cultured rat cortical neuron].

OBJECTIVE: To investigate the effect and mechanisms of dimethoate on the primary cultured cortical neuronal cell injury. METHODS: Cortical neuronal cells were isolated and cultured in serum free medium for 6 days in vitro, and 1, 5, 10, 50 and 100 micromol/L dimethoate were added to the medium and intracellular SOD, MDA and GSH. The content of excitatory amino acid was measured after 48 hours. Flow cytometry was used to detect the neuronal cell apoptosis. RESULTS: After 48 h, the activity of SOD and the content of GSH decreased [(1.04 +/- 0.02), (0.99 +/- 0.02), (0.96 +/- 0.02), (0.91 +/- 0.02) U/mg pro] [(219.35 +/- 6.79), (205.6 +/- 6.29), (194.06 +/- 2.63), (93.68 +/- 7.56) mg/g pro], and the content of MDA increased obviously with 5, 10, 50 and 100 micromol/L dimethoate [(21.22 +/- 0.29), (24.01 +/- 0.34), (27.15 +/- 1.02), (32.91 +/- 1.39) nmol/mg pro]; The content of Asp from 10 to 100 micromol/L dose group was higher than the control group and the content of Glu from 1 to 100 micromol/L dose group was higher than the control group. The apoptosis rate had great significance between 1 to 100 micromol/L dose groups and control group. When treated with dimethoate, MDA content in neuron was positively correlated with the content of EAAs with the increase of dimethoate. The correlative coefficient was 0.937 and 0.759 respectively (P < 0.01), while it was negatively correlated with the content of GSH. The correlative coefficient was -0.868 and -0.801 respectively (P < 0.01). CONCLUSION: The oxidative damage and changes of excitatory amino acid content induced by Dimethoate contribute to the primary cultured rat cortical neuron apoptosis.

[Influence of pyrrolidine dithiocarbamate (PDTC) on expression of transforming growth factor beta(1), matrix metalloproteinase-2 and tissue inhibitor-1 of metalloproteinase in rats with pulmonary damage induced by paraquat].

OBJECTIVE: To investigate the influence of pyrrolidine dithiocarbamate (PDTC) on the expression of transforming growth factor beta(1) (TGF-beta(1)), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor-1 of metalloproteinase (TIMP-1) in rats with pulmonary damage induced by paraquat (PQ). METHODS: Fifty-four healthy male SD rats were randomly assigned into the control group (normal saline), the PQ-treatment groups (4 groups) and the PDTC treatment groups (4 groups). Except the rats in the control group, the rats in the PQ group were gavaged only with 40 mg/kg PQ, and PDTC group with 40 mg/kg PQ plus immediate injection 120 mg/kg PDTC (i.p). On the 3rd, the 7th, the 14th and 28th day after treatments, one group rats of each treatments were sacrificed and lung and blood samples were collected. The level of TGF-beta(1) protein in the plasma, the mRNA expression of TGF-beta(1), MMP-2 and TIMP-1 were evaluated using RT-PCR and real-time quantitative PCR, while pathological changes of lung were examined under optical microscope and electrical microscope. RESULTS: The TGF-beta(1) protein, TGF-beta(1) and MMP-2 mRNA expression were increased significantly in the earlier stage and then decreased after PQ administration (P < 0.05 or P < 0.01), while the mRNA level of TIMP-1 was augmented continuously (P < 0.01) throughout the study compared to the control group. In comparison with the PQ group, in the PDTC treatment group, the TGF-beta(1) mRNA expression on the 3rd and the 14th day, 0.54 +/- 0.08 and 0.72 +/- 0.04 respectively, the MMP-2 mRNA expression on the 7th and 14th day, 1.62 +/- 0.50 and 1.97 +/- 0.34 respective-ly, and the TIMP-1 mRNA on the 7th and 21st day, 1.79 +/- 0.21 and 2.00 +/- 0.34 respectively, were significantly decreased (P < 0.05 or P < 0.01). CONCLUSION: PDTC could attenuate paraquat-induced up-regulation of TGF-beta(1) and its mRNA expression, MMP-2 and TIMP-1 mRNA levels, which indicates that PDTC may exert its protective effects on paraquat-induced pulmonary damage by alleviating the earlier inflammation damage and adjust-ing the balance between MMPs and TIMPs. However, further studies are still warranted to investigate and clarify the underlying mechanisms involved in this complicated process.

[Effects of 90-day oral dimethoate exposure on glutamatergic system and neurobehavioral performance in rats].

OBJECTIVE: To investigate the spatial learning and exploration along with the CNS excitatory amino acid neurotransmitters profiles in adult rats subchronically exposed to the anticholinesterase organophosphorus insecticide dimethoate. METHODS: Rats were gavaged daily with dimethoate (0, 5, 10 or 20 mg/kg via oral) in NS. for 90 days. Morris water maze tasks were used to test the spatial learning and memory in the rats after the dimethoate exposure. Simultaneously, rats were decapitated for the determination of brain cholinesterase AChE activities, glutamate concentrations, and the NMDA receptor NMDA-R densities and affinities in hippocampus. RESULTS: Latencies to find a hidden escape platform were significantly longer in dimethoate dosed groups than that of the control group in the place navigation tests. Subsequently, the times of crossing the location of platform which had been removed obviously decreased in the highest dose group compared with that of the control in the spatial probe tests (P < 0.05). AChE activity was significantly reduced 42% approximately 78% by all three doses of dimethoate (P < 0.05). Glutamate concentrations were increased significantly 132.9% approximately 134.5% by the two highest doses of dimethoate (P < 0.05). In addition, the NMDA receptor bindings were reduced 21.2% approximately 23.2% with the statistical significance at the same two highest doses (P < 0.05). Furthermore, the receptor affinities was reduced 33.1% by the highest dose group (P < 0.05). The lesions of spatial memory were statistically corrected with the decrease of the NMDA-R affinities (P < 0.05). CONCLUSION: The cholinergic lesion as well as the excitatory amino acid system alteration might attribute to the inferior ability in spatial learning and memory in dimethoate subchronically exposed rats.

Carboxylic esterase and its associations with long-term effects of organophosphorus pesticides.

OBJECTIVE: To examine a) the effect of organophosphorus pesticide exposure on activity of carboxylic esterases, namely butyrylcholinesterase (BChE), carboxylesterase (CarbE) and paraoxonase (PonE); and b) the association of polymorphisms of BChE and PonE with individual genetic susceptibility to organophosphorus pesticide exposure. METHODS: A cross-sectional study was conducted in 75 workers exposed to organophosphorus pesticides and 100 non-exposed controls. The serum activity of these enzymes was measured. Variant forms of BCHE-K, PON-192, and PON-55 were detected. A symptom score was developed as a proxy measure of clinical outcomes. RESULTS: Activities of both BChE and CarbE were lower in exposed workers (27.3+/-21.65 nmolxh(-1)xmL(-1) and 235.6+/-104.03 nmolxmin(-1)xmL(-1)) than in non-exposed workers (78.313+/-30.354 nmolxh(-1)xmL(-1) and 362.681+/-194.997 nmolxmin(-1)xmL(-1)). The activity of PonE was not associated with exposure status. The AChE activity in the exposed workers with BCHE-K genotype UU (61 cases), genotype UK (12 cases) and genotype KK (2 cases) was 105.05, 84.42 and 79.00 mmolxh(-1)xmL(-1), respectively and the accumulative symptom scores were 3.74, 9.17, and 12.50 accordingly. The AChE activity in the exposed workers with PON-192 genotypeBB (37), genotype AB (27) and genotype AA (11) was 116.8, 91.2, and 72.3 mmolxh(-1)xmL(-1), respectively and the symptom scores were 2.00, 6.74, and 9.73 accordingly. The AChE activity in those with PON-55 genotype LL (70) and genotype LM (5) was 102.4 and 82.8 mmolxh(-1)xmL(-1) and the symptom scores were 4.53 and 9.20. The symptom score was the highest in individuals with abnormal homozygote for each of the three gene loci. CONCLUSIONS: Long-term exposure to organophosphorus pesticides can inhibit BChE and CarbE activity, but exerts no inhibitory effect on PonE activity. Different genotypes of BCHE-K, PON-192, and PON-55 may be related to the severity of adverse health effects of organophosphorus pesticide exposure. Implications of potentially higher susceptibility of workers with mutant homozygotes should be evaluated to reduce health risks.

[Protective effects of vigabatrin and atropine against dimethoate induced-intoxication in mice].

OBJECTIVE: To investigate the protective effects of vigabatrin and atropine against the acute toxicity of dimethoate in male Kun-min mice. METHODS: The therapeutic schedules of vigabatrin (50 or 100 mg/kg) and (or) atropine (2.5 or 5.0 mg/kg) were performed according to the L(9) (3(4)) orthogonal test table. The survival time, the righting reflex and the onset of muscle fasciculations were observed after the administration of dimethoate. RESULTS: First, the main effects of vigabatrin, atropine and the interaction between them were statistically significant in the Univariate analysis of the survival time at the alpha level of 0.05 (F(V)= 4.73, P(V)= 0.015, F(A)= 50.88, P(A)= 0.000, F(VxA)= 4.17, P(VxA)= 0.007). The range of atropine was more than double of that of vigabatrin or their interaction (R(A)> 2RV or 2R(VxA)). So not only atropine and vigabatrin but also their combination interaction protected mice against dimethoate lethality. The atropine played the major role in diminishing the lethality induced by dimethoate. Second, only vigabatrin, while not atropine, delayed the mice from dimethoate-induced muscle fasciculation according its statistical results (F(V)= 6.87, P(V)= 0.003, F(A)= 0.03, P(A)= 0.968, F(VxA)= 1.134, P(VxA)= 0.356). It should be noted that vigabatrin could not completely prevent dimethoate induced-muscle fasciculation in the test. At last, both atropine and vigabatrin could maintain the righting reflex in the intoxication, however there was no interaction between them (F(V)= 5.81, P(V)= 0.006, F(A)= 9.05, P(A)= 0.001, F(VxA)= 1.34, P(VxA)= 0.257). CONCLUSION: Combined treatment with atropine and vigabatrin in the organophosphates intoxication seems reasonable and acceptable.

[Effect of dimethoate on dopamines neurotransmitters in brain regions of rat].

OBJECTIVE: To observe changes of dopamine and its metabolite (3,4-hydroxyphenylaceticacid, DOPAC) levels of the brain regions in rats exposed by dimethoate (DM). METHODS: Groups of rats were treated with saline and 38.9, 83.7 and 180.0 mg/kg DM respectively, and were decapitated at different time course from 0.5 to 24 hours after the administration. The dopamine neurotransmitters and its metabolite were determined by reverse-phase high-performance liquid chromatography with electrochemical detection. RESULTS: The concentrations of DA (28% - 122% of control) and DOPAC (89% - 538% of control) varied according with the DM dose and the exposure time. CONCLUSION: These results indicated that DM-induced toxic effects could alter the dopamine levels after the different dose and time exposure in the brain regions of rats.

[Effect of dimethoate on serum monoamines neurotransmitters in rats].

OBJECTIVE: To study the effect of dimethoate on the monoamine Neurotransmitters, including norepinephrine (NE), epinephrine (E), serotonin (5-HT), dopamine (DA) and its metabolite (3, 4-hydroxyphenylacetic acid, DOPAC) in the serum of rats and furthermore to explore the non-cholinergic mechanism of organophosphate induced toxicity. METHODS: Groups of rats were treated with saline and 38.9, 83.7 and 180 mg/kg dimethoate respectively and were decapitated at the different time course from 0.5 to 24 hours after the administration. The monoamines neurotransmitters were determined by the reverse-phase high-performance liquid chromatography with the electrochemical detection. RESULTS: The serum concentrations of DA (8.42% - 248.42% of the control), DOPAC (17.22% - 68.21% of the control) increased, according with the DM dosage and the exposure time, while the levels of NE (9.65% - 38.26% of the control) and E (11.00% - 32.62% of the control) contents decreased at the same time. CONCLUSION: These findings indicate that dimethoate induced toxic effects can alter the monoamine levels at the different dosage and the time exposure in the serum of rats. It suggests that some non-cholinergic mechanisms may be involved in the dimethoate intoxication.

[Activity of esterases and effect of genetic polymorphism in workers exposed to organophosphorus pesticides].

OBJECTIVE: To study the activity of esterases, including butyrylcholinesterase (BchE), carboxylesterase (CarbE), paraoxonase (PonE) and acetylcholinesterase (AChE), and to explore the effect of genetic polymorphism on the activity of esterase for workers exposed to organophosphorus pesticides (OPs). METHODS: Two hundred and forty-one long term OPs directly exposed workers and 151 indirectly exposed workers in the same factory were taken as study group. One hundred and sixty unexposed persons were taken as control group. The activity of serum enzymes was measured and the polymorphic distribution was detected using 7900 genotype detecting system and CMOS Chip technique. The effect of long-term exposure to organophosphorus pesticides was analyzed. RESULTS: The activities of BchE, CarbE and PonE were independent on the gender or age in control group. Average values of Carb and BchE activities of directly and indirectly exposed workers were lower than those in control group respectively. PonE activity in directly exposed group was lower than that in control group. AChE activity in directly exposed group was lower than that in indirectly exposed group. All the differences were significant (P < 0.01). In the direct exposure group, the frequency of three variants of butyrylcholinesterase gene K (BCHE-K) polymorphism was 74.3%, 24.1% and 1.6% for UU, UK and KK respectively. Frequency of allele U and K was 0.863 and 0.137 respectively in the same group. Frequency of three variants of PON192 polymorphism was 15.0%, 45.5% and 39.5% for AA, AB and BB respectively in direct exposure group. Gene frequency of low activity (PON*A) and high activity (PON*B) was 0.378 and 0.622 respectively. Frequency of three variants of PON55 polymorphism was 96.2%, 3.8% and 0% for MM, LM and LL respectively in direct exposure group. Frequency of allele M and L was 0.981 and 0.019 respectively in the same group. The activity of PON was different in various genotypes of PON192 and PON55. CONCLUSION: The long-term exposure to OPs could inhibit the activities of CarbE, BchE, PonE and ACh E in different level. The genetic polymorphisms of PON192 and PON55 affect the activity of PonE, which is related to the detoxification of OPs and health impact.

[Study on monoamine neurotransmitters in rat serum and brain tissue by high performance liquid chromatography with electrochemical detection].

OBJECTIVE: A rapid, reliable and simple method detecting monoamine neurotransmitters in rat serum and brain tissue by high performance liquid chromatography with electrochemical detector was developed. METHODS: An ODS column was selected as separation column at room temperature,and the mobile phase (pH4.50) consisted of 0.02 mol/L trisodium citrate and 0.05 mol/L disodium phosphate, containing 15% methanol (volume ratio)in distilled water. The mobile phase was pumped at a flow rate of 1.0 ml/min and the oxidation potential was set at +0.065 mV. Dihydroxybenzylamine was used as the internal standard for quantification. Four compounds, epinephrine (E), dopamine (DA) and 5-hydroxytryptamine(5-HT) in the brain tissue ((whole cerebral cortex, hippocampus, striatum, midbrain, cerebellum) and serum were simultaneously separated and determined under the above conditions. RESULTS: RSD of the retention times and peak areas of standard sample was in the range 0.29%-0.67% and 0.09%-0.36%. The recoveries of all analytes were over 85%. The detection limits of 0.083 ng/ml for NE, 0.51 ng/ml for E, 0.046 ng/ml for DA and 0.078ng/ml for 5-HT were achieved with standard solutions. The linearity is over the range 1.0-100 ng/ml for NE, 5.0-80 ng/ml for E,1.0-80 ng/ ml for DA and 1.0-60 ng/ml for 5-HT. CONCLUSION: The assay had been applied successfully to measure simultaneously cortex and serum concentrations of these four monoamines in rats.

[Effect of dimethoate on the expression of heat shock protein 70 in peripheral blood lymphocytes of human beings].

OBJECTIVE: To study the effect of dimethoate on the expression of heat shock protein 70 (HSP70) in peripheral blood lymphocytes of human beings and to explore the feasibility of HSP70 in biomonitoring among workers exposed to organophosphorous pesticides. METHODS: Peripheral blood lymphocytes were isolated from subjects, comprising 11 people of the control group and 35 workers of the exposure group exposed to dimethoate. Flow cytometry was used for detecting both the basic level and the level of the dimethoate-induced expression of HSP70. The activity of whole blood acetylcholinesterase (AChE) was examined at the same time. Then the potential influential factors to HSP70 expression and AChE activity were analyzed. RESULTS: The basic level of HSP70 expression in the exposure group and the control group was 41.24% +/- 10.45% and 23.97% +/- 4.29% respectively. The activity of AChE in these two groups were (125.23 +/- 7.97) and (145.36 +/- 8.78) U/ml respectively. Both differences were statistically significant (P < 0.01). Among the exposure group, the basic level of HSP70 expression of the two categories comprising operators and packers, were 47.34% +/- 11.87% and 38.05% +/- 8.20% respectively (P < 0.05), while there was no significant difference (P > 0.05) in AChE activity between these two categories. The factors that had significant influence on the HSP70 basic level of the exposure group were the health condition, the environmental concentration of dimethoate and the exposure time in order, according to their significance of influence. At least 88% variance of HSP70 could be explained by these factors. The only factor that could influence AChE activity significantly was the exposure time, and it could only explain about 12% variance of AChE activity. After the treatment of dimethoate in vitro, the level of the induced expression of HSP70 in the control group was significantly higher than that of the exposure group (P < 0.01). The increasing order was the control group, the group of packers and the group of operators according to the increasing extent and there were significant difference among them (P < 0.01). The factors that could significantly influence the change ratio of HSP70 expression were the environmental concentration and the exposure time. CONCLUSION: HSP70 is a potential index that can reflect the individual and environmental conditions of workers exposed to dimethoate comprehensively.

An overview of published benzene exposure data by industry in China, 1960-2003.

This article presents an overview of occupational benzene exposures in China based on data published in Chinese medical journals. The data were derived from 384 reports of benzene poisoning or industrial hygiene surveys published in Chinese medical journals between 1960 and 2003. The following information was extracted whenever available: industry, occupation, task, date, benzene levels, sampling location, workplace descriptions and, for case reports, medical diagnosis. Each paper provided one or more sets of benzene data, each set representing a sampling location or job title with one to several measurements including, mainly, breathing zone area concentration measurements, and much less frequently personal monitoring. Two criteria based on data quality were applied to select suitable data for analyses. The selected exposure data were analyzed by industry and time period. Nine hundred five sets of benzene measurements from 72 industries were reported in the 384 papers selected for this review, and 621 sets (68.6%) presented average benzene concentrations, which covered 55 industries. The distribution of the reported average benzene exposures was skewed with a median of 51.5 mg/m3. The average benzene concentrations were below 100 mg/m3 for 406 (65%) of the 621 reported average concentrations. The medians of the reported averages in mg/m3 for the five industries with the highest exposures were: 124.8 for leather products, 98.7 for electronic devices, 75.4 for machinery, 50.4 for shoes, and 50.3 for office supplies and sports equipment manufacturing. These data describe the concentrations and changing patterns of occupational benzene exposure by industry and time period in China.