Progress on the mechanism of n-hexane induced toxic effects in vitro and in vivo / 中华劳动卫生职业病杂志

Hexane is a widely used organic solvent in industry, and chronic hexane poisoning is the main occupational toxic lesion in China. In particular, axonal and myelin lesions in the distal thick fibers of the peripheral nervous system may be caused by 2, 5-hexanedione (2, 5-HD), an intermediate metabolite of n-hexane in humans. Hexane has toxic effects not only on the nervous system but also on the liver, kidneys, and reproductive organs. In this paper, we review the progress of research on the mechanism of n-hexane toxic neuropathy.

Readspace solid-phase microextraction-gas chromatography for determination of 2,5-hexanedione in urine / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To establish a method for determination of 2,5-hexanedione in urine by headspace solid-phase microextraction-gas chromatography.</p><p><b>METHODS</b>After extraction by solid-phase microextraction head, 2,5-hexanedione in urine was determined by gas chromatography and was quantified by external standard method.</p><p><b>RESULTS</b>The concentration of 2,5-hexanedione in urine showed a linear relationship within the range of 0.1-20.0 µg/ml. The regression equation was y=261.36x-1.903 3, r=0.999 2. The minimum detectable concentration was 0.01 µg/ml. The recovery rate was 92.6%-97.1%, with a relative standard deviation (RSD) of 3.3%-5.8%. The intra-day and inter-day RSDs were 3.8%-6.2% and 4.7%-6.3% respectively.</p><p><b>CONCLUSION</b>This determination method has no requirement for organic solvents, features simple and rapid operation, possesses higher detection sensitivity, and applies well to the determination of 2,5-hexanedione in urine.</p>

Formation of pyrrole adducts in 2,5-hexanedione-containing human serum cultured in vitro / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the relationship between formation of pyrrole adducts and concentration of 2, 5-hexanedione (2, 5-HD) and to provide an experimental basis for the study on toxicity of n-hexane.</p><p><b>METHODS</b>Serum samples were collected from normal persons and were then filtered and sterilized. They were mixed with 2,5-HD to obtain sera with final 2, 5-HD concentrations of 10, 25, 50, 100, and 200 mg/L, and blank serum was also prepared. The sera were cultured at 37°C and taken at different time points. Colorimetry was used to quantify the pyrrole adducts formed in sera, and gas chromatography was used to measure the remaining 2, 5-HD levels in sera.</p><p><b>RESULTS</b>The content of pyrrole adducts increased as the culture proceeded and was dependent on the dose of 2, 5-HD; at the end of the experiment, the content of pyrrole adducts differed significantly across all concentration groups (P < 0.5). The concentrations of 2,5-HD decreased as the culture proceeded; at the end of the experiment, the concentrations of 2, 5-HD, from the highest to the lowest, decreased by 29%, 55%, 22%, 44%, and 40%, respectively. The decrease in 2, 5-HD had a positive correlation with the increase in pyrrole adducts, and the correlation coefficients for 200∼10 mg/L 2, 5-HD were 0.865, 0.697, 0.835, 0.823, and 0.814, respectively.</p><p><b>CONCLUSION</b>The content of formed pyrrole adducts increases as the concentration of 2,5-HD rises; there is a positive correlation between the decrease in 2, 5-HD and the increase in pyrrole adducts in human serum.</p>

Studying the damages of mouse retina induced by 2,5-hexanedione / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study toxic effects of 2,5-hexanedione (2,5-HD) on pathology and lipid peroxidation in mouse retina.</p><p><b>METHODS</b>Forty-eight mice were randomly divided into blank control group (12 mice), negative control group exposed to normal solution (12 mice) and group exposed to 2,5-HD for 2. 4 and 8 weeks, respectively (24 mice) by intraperitoneal injection (2.5% 2,5-HD) at the dose of 400 mg/kg. The pathological changes of mouse retina were examined under light microscope. The activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in mouse retina were detected.</p><p><b>RESULTS</b>The retinal structure in the blank and negative control groups was normal. In mice exposed to 2,5-HD for 8 weeks, the swelling of outer and inner segments and disorder arrangement of the segments without clear boundary were found. The staining of outer plexiform layers was uneven and the irregular loose structure appeared. The hyperchromatic pyknotic and necrosis nuclei were presented in ganglion cells layer. Compared with the control and blank groups, the activities of SOD gradually and significantly reduced and the concentrations of MDA increased in group exposed to 2,5-HD (P < 0.05).</p><p><b>CONCLUSION</b>2,5-HD can induce the injury of retina tissues of mice, which may be associated with the lipid peroxidation.</p>

Effect of 2,5-hexanedione on light-molecular-weight neurofilaments (NF-L) degradation of rat nerve tissues / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of 2,5-hexanedione (HD) on degradation of low-molecular-weight neurofilaments (NF-L) in nervous tissue of rats, and to explore the molecular mechanism of n-hexane neuropathy.</p><p><b>METHODS</b>Fifty male Wistar rats were randomly divided into one-week poisoning group (n = 10), two-week poisoning group (n = 10), three-week poisoning group (n = 10), four-week poisoning group (n = 10), and control group (n = 10). In the four poisoning groups, a rat model of n-hexane neuropathy was established by intraperitoneal injection of HD (400 mg/kg/d). The change in the sciatic nerve ultrastructure of each rat was observed under an electron microscope. The progression of HD-induced peripheral neuropathy was evaluated using a gait scoring system. The degradation rates of NF-L in the sciatic nerve and spinal cord of each rat were measured by Western Blotting.</p><p><b>RESULTS</b>The rats showed decrease in muscle strength and abnormal gait after two weeks of HD poisoning and mild or moderate paralysis after four weeks of HD poisoning. The sciatic nerve showed degenerative change, according to electron microscope observation. Compared with the control group, the two-week poisoning group, three-week poisoning group, and four-week poisoning group had the NF-L degradation rates decreased by 25.8%, 70.4%, and 69.7%, respectively, in the supernatant fraction of sciatic nerve, and by 14.7%, 64.6%, and 67.3%, respectively, in the sediment fraction of sciatic nerve, all showing a significant difference (P < 0.01). Compared with the control group, the one-week poisoning group had the NF-L degradation rate decreased by 33.87% in the supernatant fraction of spinal cord, the four-week poisoning group had the NF-L degradation rate increased by 16.2% in the supernatant fraction of spinal cord, and the one-week poisoning group and two-week poisoning group had the NF-L degradation rates decreased by 46.3% and 13.0% in the sediment fraction of spinal cord, all showing a significant difference (P < 0.01).</p><p><b>CONCLUSION</b>HD poisoning significantly inhibits NF-L degradation in the sciatic nerve, which may be associated with NF degeneration and accumulation in the axons of patients with n-hexane neuropathy.</p>

The effect of 2,5-hexanedione on myelin protein zero expression, and its mitigation using Ginkgo biloba extract / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the role of myelin protein zero (P(0)) in 2,5-hexanedione (2,5-HD)-induced peripheral nerve injury, and the protective effect of Ginkgo biloba extract (Egb761) on 2,5-HD-induced toxic peripheral neuropathy.</p><p><b>METHODS</b>After 4 weeks of treatment with 2,5-HD at different doses (50, 100, 200, 400 mg/kg) in rats, changes in the levels of P(0) in rat sciatic nerves was investigated, and the effect of Egb761 on 2,5-HD-induced toxic peripheral neuropathy was studied.</p><p><b>RESULTS</b>The blood-nerve barrier (BNB) permeability of the sciatic nerve increased, and the expression of P(0) mRNA and P(0) protein decreased in a dose-dependent manner after treatment with 2,5-HD for 4 weeks. Pretreatment with Egb761 protected against BNB interruption, and inhibited P(0) mRNA and protein reduction during 2,5-HD treatment. Pretreatment with Egb761 significantly reduced loss of body weight (P<0.01) and mitigated gait abnormalities (2.85±0.22) induced by 400 mg/kg 2,5-HD (P<0.01). It also reduced the signs of neurotoxicity induced by 2,5-HD.</p><p><b>CONCLUSION</b>2,5-HD inhibited the expression of P(0) in a dose-dependent manner, and this may be an important mechanism by which toxic peripheral neuropathy is induced by 2,5-HD. Egb761 has a protective effect against 2,5-HD-induced peripheral neurotoxicity in rats.</p>

Effects of garlic oil, age and sex on n-hexane metabolism in rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate effects of garlic oil (GO), age and sex on n-hexane metabolism in rats.</p><p><b>METHODS</b>The Wistar rats were used as experimental animals. (1) Intragastric administration: n-hexane group (3000 mg/kg n-hexane), GO treated group (80 mg/kg GO ig. an hour earlier than 3000 mg/kg n-hexane), then blood was taken from tails of rats at 8, 12, 16, 20, 24, 28, 32 h points after n-hexane administration. (2) Intraperitoneal injection: n-hexane group (1000 mg/kg n-hexane), GO treated group (80 mg/kg GO ig. an hour earlier than 1000 mg/kg n-hexane), then took blood was taken from tails of rats at 8, 12, 16, 20, 24, 28 h points after n-hexane injection. (3) 7 rats each group of 6, 8, 10 weeks age were administrated by 3000 mg/kg n-hexane intragastrically, then were taken blood from tails at 16, 20, 24 h points after administration. (4) 7 male and 7 female rats of 8 weeks age were administrated by 3000 mg/kg n-hexane intragastrically, then were taken blood from tails at 16, 20, 24, 28 h points after administration. The gas chromatography was used to determine the metabolite 2, 5-hexanedione concentration of n-hexane in serum and 2, 5-hexanedione concentration was compared between GO and no GO treated rats, different ages and different sexes.</p><p><b>RESULTS</b>(1) Intragastric administration: 2, 5-hexanedione concentrations in serum of n-hexane group and GO treated group had the peak 19.2 and 12.3 µg/ml at 20h and 24 h points. Compared with n-hexane group, the serum 2, 5-hexanedione concentration of GO treated group was lower at time points prior to peak and 2, 5-hexanedione eliminating process was slower after peak. (2) Intraperitoneal injection: effects of GO on the serum 2, 5-hexanedione concentrations was very similar to intragastric administration, 2, 5-hexanedione concentrations in serum of n-hexane group and GO treated group had the peak 15.0 and 6.7 µg/ml at 12 h and 16 h points. (3) Comparison of the serum 2, 5-hexanedione concentrations of different weeks age rats: The serum 2, 5-hexanedione concentrations of 6, 8, 10 weeks age rats were 25.5, 15.0, 12.8 µg/ml each (8, 10 weeks age significantly lower than 6 weeks age) at 16 h point; at 20 h point, they were 24.7, 18.3, 15.0 µg/ml each (10 weeks age significantly lower than 6 weeks age); at 24 h point, they were 11.0, 14.7, 8.1 µg/ml each (10 weeks age significantly lower than 8 weeks age). (4) Comparisons of the serum 2, 5-hexanedione concentrations of different sex rats: the serum 2, 5-hexanedione concentrations of male and female rats were 22.5, 17.2 µg/ml each at 16 h point (different significantly); at 20, 24, 28 h points, they were 27.6, 22.9 µg/ml, 24.6, 19.1 µg/ml, 19.1, 13.8 µg/ml each (different non-significantly).</p><p><b>CONCLUSION</b>GO reduces production of 2, 5-hexanedione in serum generated by n-hexane in rats; the metabolic capacity of low age rats on n-hexane is stronger than high age ones.</p>

External Quality Assessment Scheme for Biological Monitoring of Occupational Exposure to Toxic Chemicals

OBJECTIVES: In this study, we summarized the External Quality Assessment Scheme (EQAS) for the biological monitoring of occupational exposure to toxic chemicals which started in 1995 and continued until a 31st round robin in the spring of 2010. The program was performed twice per year until 2009, and this was changed to once a year since 2010. The objective of the program is to ensure the reliability of the data related to biological monitoring from analytical laboratories. METHODS: One hundred and eighteen laboratories participated in the 31st round robin. The program offers 5 items for inorganic analysis: lead in blood, cadmium in blood, manganese in blood, cadmium in urine, and mercury in urine. It also offers 10 items for organic analysis, including hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid, N-methylformamide, N-methylacetamide, trichloroacetic acid, total trichloro-compounds, trans,trans-muconic acid, and 2,5-hexanedione in urine. Target values were determined by statistical analysis using consensus values. All the data, such as chromatograms and calibration curves, were reviewed by the committee. RESULTS: The proficiency rate was below 70% prior to the first round robin and improved to over 90% for common items, such as PbB and HA, while those for other items still remained in the range of 60-90% and need to be improved up to 90%. CONCLUSION: The EQAS has taken a primary role in improving the reliability of analytical data. A total quality assurance scheme is suggested, including the validation of technical documentation for the whole analytical procedure.

The effect of 2,5-hexanedione on nerve growth factor in sciatic nerve of rats and VSC4.1 cell / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the effect of 2,5-hexanedione (2,5-HD) on the levels of nerve growth factor (NGF) in sciatic nerve of rats and motor-neurons.</p><p><b>METHOD</b>A total of 50 Wistar rats were randomly designed into five groups and intoxicated with 400 mgxkg(-1)xd(-1) 2,5-HD for 0, 7, 14, 21, 28 d. Immunohistochemistry and real-time PCR were used to detect the levels of NGF and NGF mRNA. Motor neuron VSC4.1 cells were administrated with 0, 2.5, 5.0, 10.0, 20.0 mmol/L 2,5-HD for 24 h and 10.0 mmol/L 2,5-HD was chosen to intoxicated VSC4.1 cells for 0, 1, 3, 6, 12, 24, 48 h respectively. Immunofluorescence technique was selected to detect the levels of NGF.</p><p><b>RESULTS</b>The NGF level in sciatic nerve of rats administrated with 400 mgxkg(-1)xd(-1) 2,5-HD showed increase tendency at begin and then decrease after exposure. The NGF mRNA level in 14 d (2(-DeltaDeltaCt)= 3.46), 21 d (2(-DeltaDeltaCt)= 5.28) and 28 d (2(-DeltaDeltaCt)= 3.10) were higher than those in 0 d (2(-DeltaDeltaCt)= 1) and 7 d (2(-DeltaDeltaCt)= 0.78). In vitro tests of VSC4.1 cells showed that NGF levels in 5.0 mmol/L (43.24 +/- 7.52), 10.0 mmol/L (43.48 +/- 10.86) and 20.0 mmol/L (63.13 +/- 10.68) were higher than those in 0 mmol/L (16.32 +/- 4.20)(q values were 19.92, 19.72, 32.78, respectively, P < 0.01) and 2.5 mmol/L (19.78 +/- 2.66) (q values were 17.50, 17.42, 30.63, respectively, P < 0.01) in 24 h and the NGF level in 20.0 mmol/L was higher than those in 5.0 mmol/L (q = 13.04, P < 0.01) and 10.0 mmol/L (q = 11.71, P < 0.01). The NGF levels of VSC4.1 cells with 10.0 mmol/L 2,5-HD in 6 h (18.66 +/- 2.89), 12 h (23.14 +/- 6.08), 24 h (27.66 +/- 6.11) and 48 h (17.25 +/- 3.05) were increased compared with that in 0 h (10.18 +/- 1.81) (q values were 9.64, 15.74, 21.76, 8.50, respectively, P < 0.01), 1 h (9.31 +/- 1.28) (q values were 10.28, 16.17, 21.95, 9.20, respectively, P < 0.01) and 3 h (10.44 +/- 2.13) (q values were 9.25, 15.24, 21.17, 8.10, respectively, P < 0.01), and NGF levels in 12 h and 24 h increased compared with those in 6 h (q values were 5.24, 10.77, respectively, P < 0.01) and 48 h (q values were 7.31, 13.26, respectively, P < 0.01).</p><p><b>CONCLUSION</b>2,5-HD could increase NGF levels in sciatic nerve of rats and motor-neurons, and the dose or time dependent effects were observed in this study.</p>

Effects of garlic oil on n-hexane metabolized to 2, 5-hexanedione in mice serum / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effects of garlic oil (GO) on n-hexane metabolized to 2, 5-hexanedione (2, 5-HD) in mice.</p><p><b>METHODS</b>Adult healthy Kunming-mice were treated with n-hexane and GO. The serum was obtained and extracted with ethyl acetate, and the levels of the serum 2, 5-HD were determined by gas chromatography.</p><p><b>RESULTS</b>(1) The concentration of 2, 5-HD in serum increased firstly after a single exposure to n-hexane (4 000 mg/kg). The peak value occurred at 10 hours after n-hexane treatment, but could hardly be detected at 20 h. (2) There was no 2, 5-HD in serum of control mice. The content of 2, 5-HD in serum increased along with the exposure dose of n-hexane. The serum 2, 5-HD contents of the 2000, 4000 and 6000 mg/kg groups mice were 8.04, 16.68 and 22.38 microg/ml at 8 h in pretreated mice, respectively, and showed significant dose-effect relationship. (3) When the different age mice were exposed to the same dose of n-hexane, the contents of 2, 5-HD in serum were significantly different after 8 hours (P<0.05). The serum 2, 5-HD level of the 5 weeks old mice (22.83 microg/ml) was much higher than the 4 (19.59 microg/ml) and 6 (16.42 microg/ml) weeks old mice. (4) When the different gender mice were exposed to the same dose of n-hexane, the concentration of 2, 5-HD in serum of female mice (13.22 microg/ml) was higher than that of the female mice (10.34 microg/ml, P<0.05). (5) GO significantly inhibited the increase of the serum 2, 5-HD levels of both the pretreatment and post-treatment groups treated with 80 mg/kg n-hexane respectively, but the pretreatment with GO exhibited the more suppressive effects than the post-treatment (P>0.05). Compared with the n-hexane group, the concentrations of serum 2, 5-HD in GO-pretreated groups mice decreased by 16.2%, 20.8%, 22.8% (P<0.05) and 32.1% (P<0.01), respectively, and showed significant dose-effect relationship.</p><p><b>CONCLUSION</b>The serum content of 2, 5-HD, the metabolite of n-hexane, is different in different genders and age mice after exposed to the same dose of n-hexane. GO can effectively inhibit the production of n-hexane metabolized to 2, 5-HD in mice serum.</p>

A Case of Trichloroethylene Intoxication with Neuropsychiatric Symptoms / 대한산업의학회지

BACKGROUND: Trichloroethylene (TCE) has been widely used as a typewriter correction fluid, paint remover, adhesive, spot removers and, particularly, as a degreasing agent in metal-fabricating operation. However, few studies have reported on the effects of TCE intoxication, in spite of numerous occupational accidents arising from TCE intoxication, even until quite recently used in small companies. TCE affects mainly the central nervous system (CNS) and is carcinogenic, even when carefully used and managed. CASE REPORT: A 48-year-old male worker visited our hospital complaining of decreased motivation and general weakness. In history taking, the patient had suffered insomnia, memory disturbance, stuttering, loss of interest and sexual desire, depressive mood for 4 years, dysesthesia with tingling sensation and pain in both extremities, and a nauseas feeling similar to a hangover which had been aggravated for 4 months before admission. The patient had been engaged in metal degreasing with TCE for 8 years. Electromyography indicated disturbance of autonomic function, but there was neither peripheral neuropathy nor cervical radiculopathy. Organic abnormalities including cerebellar atrophy and CNS infection were ruled out, while there was no indication of malignancy in magnetic resonance imaging (MRI) and metabolic disorders and electrolyte imbalances in laboratory test. The authors performed biological monitoring for the possible exposed chemicals. Urinary 2,5-hexanedione, a metabolite of n-hexane, was undetected but 3,331.1 mg/g creatinine of urinary trichloro-compounds, a metabolite of TCE, was detected. The patient was diagnosed as TCE intoxication due to a level of urinary trichloro-compounds in excess of the normal range (300 mg/g creatinine), in addition to an occupational history and clinical symptoms. TCE exposure was stopped in admission and the neuropsychiatric symptoms of the patient were improved as the urinary trichloro-compounds were decreased from 3,331.1 mg/g creatinine to 64.6 mg/g creatinine in 5 days. CONCLUSION: Low-dose, chronic TCE intoxication shows neuropsychiatric symptoms, which are often misrecognized merely as a psychiatric disorder; its appropriate diagnosis, early treatment and exposure assessment are therefore difficult. The neuropsychiatric symptoms in workers who have been exposed to TCE should be monitored, detailed job history should be taken and biological monitoring should be conducted to gain early insight of chronic TCE exposure.

A Case of Trichloroethylene Intoxication with Neuropsychiatric Symptoms / 대한산업의학회지

BACKGROUND: Trichloroethylene (TCE) has been widely used as a typewriter correction fluid, paint remover, adhesive, spot removers and, particularly, as a degreasing agent in metal-fabricating operation. However, few studies have reported on the effects of TCE intoxication, in spite of numerous occupational accidents arising from TCE intoxication, even until quite recently used in small companies. TCE affects mainly the central nervous system (CNS) and is carcinogenic, even when carefully used and managed. CASE REPORT: A 48-year-old male worker visited our hospital complaining of decreased motivation and general weakness. In history taking, the patient had suffered insomnia, memory disturbance, stuttering, loss of interest and sexual desire, depressive mood for 4 years, dysesthesia with tingling sensation and pain in both extremities, and a nauseas feeling similar to a hangover which had been aggravated for 4 months before admission. The patient had been engaged in metal degreasing with TCE for 8 years. Electromyography indicated disturbance of autonomic function, but there was neither peripheral neuropathy nor cervical radiculopathy. Organic abnormalities including cerebellar atrophy and CNS infection were ruled out, while there was no indication of malignancy in magnetic resonance imaging (MRI) and metabolic disorders and electrolyte imbalances in laboratory test. The authors performed biological monitoring for the possible exposed chemicals. Urinary 2,5-hexanedione, a metabolite of n-hexane, was undetected but 3,331.1 mg/g creatinine of urinary trichloro-compounds, a metabolite of TCE, was detected. The patient was diagnosed as TCE intoxication due to a level of urinary trichloro-compounds in excess of the normal range (300 mg/g creatinine), in addition to an occupational history and clinical symptoms. TCE exposure was stopped in admission and the neuropsychiatric symptoms of the patient were improved as the urinary trichloro-compounds were decreased from 3,331.1 mg/g creatinine to 64.6 mg/g creatinine in 5 days. CONCLUSION: Low-dose, chronic TCE intoxication shows neuropsychiatric symptoms, which are often misrecognized merely as a psychiatric disorder; its appropriate diagnosis, early treatment and exposure assessment are therefore difficult. The neuropsychiatric symptoms in workers who have been exposed to TCE should be monitored, detailed job history should be taken and biological monitoring should be conducted to gain early insight of chronic TCE exposure.

Dynamic study of neurofilament contents in rat's spinal cord induced by 2, 5-hexanedione / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the dynamic changes of neurofilament contents in rat's spinal cord induced by 2, 5-hexanedione (2, 5-HD), and explore the molecular mechanism of n-hexane neuropathy.</p><p><b>METHODS</b>Male Wistar rats were administered at a dosage of 400 mg/kg/day 2, 5-HD for 2, 4 and 8 weeks respectively. HD-induced neurological defects were detected and quantified using gait score, and the relative lev-els of NF-H, NF-M, and NF-L in spinal cords of rats were determined by Western Blotting.</p><p><b>RESULTS</b>Exposure to 2, 5-HD produced progressive gait abnormalities, which suggested that the rat model of 2, 5-HD-induced neurotoxicity was established successfully. Western-Blotting results showed that NFs content in spinal cord demonstrated a progressive decline as the intoxication continued. In the supernatant fraction, compared to the controls, NF-H con-tent decreased by 15.7%, 57.0%, and 58.0% respectively after 2, 4, and 8-week treatment with 2, 5-HD (P < 0.01); accordingly, NF-M decreased by 36.0%, 61.3%, and 65.2% respectively (P < 0.01); NF-L decreased by 20.8%, 43.9%, and 44.3% respectively (P < 0.01). In the pellet fraction, the contents of NF-H in groups of 4 and 8 weeks' exposure to HD decreased by 35.6% and 43.2%, respectively (P < 0.01), and those of NF-L decreased by 26.4% and 42.1%, respectively (P < 0.01) when compared to the control. Further-more, NF-M contents in groups of 2, 4 and 8 weeks' exposure decreased by 23.3%, 33.9%, and 63.7% respectively (P < 0.01). The NFs level in spinal cords was highly correlated with gait abnormality of treated rats as the intoxication went on. Multiple correlation coefficients of NF-H, NF-M, and NF-L content with gait score of HD-treated rat were 0.8912, 0.9282 and 0.8981 (P < 0.01) respectively.</p><p><b>CONCLUSION</b>The declines of NFs are high-ly related to neurobehavioral abnormality of 2, 5-HD-treated animals, and involved in the development of n-hexane neuropathy.</p>

Effects of garlic oil on 2, 5-HD induced lipid peroxidation damage in rat nerve tissues / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effects of garlic oil (GO) against the peroxidation damage of rat nerve tissue and the peripheral motor neuropathy induced by 2, 5-HD.</p><p><b>METHODS</b>Male Wistar rats were divided into four groups, with 10 in each group. The model group, and low and high doses of GO groups were administrated with 2, 5-HD (ip, 300 mg/kg), respectively; The control group was treated with sodium chloride, five times per week for six weeks. Pretreatment with GO gavaged (40 mg/kg or 80 mg/kg) started one week be-fore 2, 5-HD treatment, and lasted to the end of the experiment. Neurobehavioral indexes were examined at the zero, second and fourth week. At the end of the experiment, the scores of the gait, and the concentration of MDA and GSH, the level of TAOC and the ability of inhibition of.OH in cerebrum, spinal cord and sciatic nerve were examined.</p><p><b>RESULTS</b>Compared with the zero week, except of the control group rats, the hind limb landing foot splay of three groups rats decreased by 44%, 50% and 49% at the fourth week, respectively without significant difference. The threshold value of balance in model, GO low and high doses groups rats decreased by 30%, 45% and 68% at the fourth week, respectively, and lower than the control group rats (P < 0.01). GO low and high doses groups rats showed the serious abnormality at the fourth week, before one week of the model group rats. The scores of gait of model, and GO low and high doses groups rats increased significantly compared with control group rats, and the GO high dose group rats were higher than model group rats (P < 0.05). Increase of the concentration of MDA, and decrease of the level of the ability of inhibition of.OH were induced by 2, 5-HD in cerebrum, spinal cord and sciatic nerve. The concentration of MDA increased, and the level of the ability of inhibition of.OH decreased (P < 0.05 or P < 0.01), respectively. The results showed that the concentration of MDA decreased, and the level of the ability of inhibition of.OH induced by GO in cerebrum, spinal cord and sciatic nerve increased, the concentration of MDA of GO low doses group rats decreased, the level of the ability of inhibition of.OH increased, the concentration of MDA of GO high doses group rats decreased (P < 0.01) respectively, and the level of the ability of inhibition of.OH increased (P < 0.01) in nerve tissue.</p><p><b>CONCLUSION</b>GO has antagonist effect on the 2, 5-HD induced peroxidation damage, but can not improve the function of the peripheral motor nerve, indicating that the lipid peroxidation does not play an important role in 2, 5-HD neurotoxicity.</p>

Resveratrol reestablishes spermatogenesis after testicular injury in rats caused by 2, 5-hexanedione / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Environmental toxins can destroy the physiological process of spermatogenesis and even lead to male infertility. Resveratrol (RES) is a natural phytoalexin with a wide range of biological activities. Some recent researches have demonstrated that RES can increase sperm output and protect sperm from apoptosis caused by physical damage. However, there is no evidence indicating that it can also exhibit a similar activity in testis injury caused by environmental toxins. This study was designed to evaluate the protective effect of resveratrol on testis damaged by environmental toxins and to elucidate the possible mechanism of its protective effect.</p><p><b>METHODS</b>In this study 2, 5-hexanedione (2, 5-HD) was used as the injury agent. Forty male SD rats were randomly divided into 5 groups. During the first 5 weeks, group A was raised normally, groups B, C, D and E were exposed to 1% 2, 5-HD; during the following 9 weeks, group C, D, E received intragastric administration of different concentrations of resveratrol (20 mg x kg(-1) x d(-1), 40 mg x kg(-1) x d(-1) and 80 mg x kg(-1) x d(-1)), while groups A and B were treated by carboxymethylcellulose. Physical signs, body weight gain and testis weight were comparatively observed. Numbers and diameters of seminiferous tubules were analyzed following HE staining. In addition, expression of the c-kit protein and gene in spermatogenic cells in every group was detected with immunohistochemistry, Western blot or RT-PCR.</p><p><b>RESULTS</b>The 2, 5-HD treatment resulted in physical signs that became worse and in emarciated testis. HE staining and immunohistochemistry showed that seminiferous tubules became emarcid, obsolete spermatogonia being stagnant and expression of c-kit protein being depressed. After oral administration of resveratrol, the 2, 5-HD-induced physical signs were improved and close to the normal rats. The gain of body weight increased (P < 0.01). The recovery of testis weight was significant (P < 0.01). At the histological level, the seminiferous epithelia began to differentiate (P < 0.01); and even the physiological process of spermatogenesis restarted. Moreover, expression of c-kit protein and gene function resumed, although its expression remained different from the normal group. The diameter of and number of seminiferous tubules and the expression level of c-kit protein and gene activity were much closer to the normal group with increased doses of the resveratrol through oral administration.</p><p><b>CONCLUSIONS</b>Resveratrol could ameliorate markedly the dyszoospermia induced by 2, 5-HD and induce spermatogenesis. The expression of c-kit, which is a specific marker protein of spermatogenic cell membranes, could be regulated by resveratrol.</p>

Expression changes of cyclin dependent kinase 5/p35 in nerve tissues of 2, 5-hexanedione intoxicated rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the role of cyclin dependent kinase 5 (CDK5) in 2, 5-hexanedione (HD)-induced neuropathy.</p><p><b>METHODS</b>Thirty male Wistar rats weighted 200 approximately 240 g were divided randomly into three groups, i.e. control group, 200 mg/kg HD group and 400 mg/kg HD group (n = 10 for each group). HD was administered to rats by intraperitoneal injection at dosage of 200 or 400 mg/kg for 8 weeks (five times per week) to establish the intoxicated rats model. The relative contents of CDK5, p35 and p25 were determined in cerebrum, spinal cord and sciatic nerve of rats by Western Blotting.</p><p><b>RESULTS</b>Compared with that of the control group rats, p35 contents were significantly decreased (P < 0.01) in the cytosolic fractions of cerebrum and spinal cord in both the 200 and 400 mg/kg HD intoxicated rats, while in the membrane fractions of spinal cord and sciatic nerve, p35 contents were increased significantly (P < 0.01). The changes of p25 showed the same pattern with p35. P25 contents were significantly reduced (P < 0.05) in the cytosolic (cerebrum and spinal cord) and membrane (cerebrum) fractions of both HD-treated rats and were elevated (P < 0.01) in the membrane fraction of spinal cord and cytosolic fraction of sciatic nerve. The relative amounts of CDK5 were significantly decreased (P < 0.01) in the cytosolic and membrane fractions of cerebrum in both the 200 and 400 mg/kg HD intoxicated rats. Except for membrane fraction of sciatic nerve, the significant increased (P < 0.01) of CDK5 were observed in the spinal cord and sciatic nerve of both the 200 and 400 mg/kg HD treated rats.</p><p><b>CONCLUSION</b>HD can induce significant changes of CDK5 and its activators p35, p25 in nerve tissues, which may be related to the neuropathy induced by HD.</p>

Resveratrol helps restore spermatogenesis after testis injury induced by 2,5-hexanedione / 中华男科学杂志

<p><b>OBJECTIVE</b>To study the effect of resveratrol on spermatogenesis after 2,5-hexanedione(2,5-HD)-induced testicular injury.</p><p><b>METHODS</b>Forty male SD rats were randomly divided into 5 groups. Group A were normally raised and Group B, C, D and E exposed to 1% 2,5-HD for 5 weeks, followed by administration of resveratrol of different concentrations (20, 40 and 80 mg/[ kg x d], respectively) to Group C, D and E for 9 weeks. Then the rats were killed, their physical signs, body weight gain and testis weight were assessed, and immunohistochemistry and Western blot analysis used to investigate the numbers and diameters of seminiferous tubules and the expression of c-kit protein of spermatogenic cell membrane.</p><p><b>RESULTS</b>The rats exposed to 2,5-HD showed weak body, lax skin, dim color pattern, tardy body weight gain, and emaciated testis. Immunohistochemistry revealed emaciated seminiferous tubules, stagnant obsolete spermatogonia and negative expression of c-kit protein. After resveratrol administration, the 2,5-HD-induced physical signs were improved and close to normal. Compared with those of the 2,5-HD injured group, the body weight and testis weight of the resveratrol treated group increased obviously (P < 0.01); and the aliquots of the seminiferous epithelia began to differentiate and the spermatogenesis and expression of c-kit protein partly resumed (P < 0.01). With increasing dose of resveratrol, the diameters and numbers of seminiferous tubules (P < 0.01) and the expression levels of c-kit protein (P < 0.01) were gradually and significantly restored almost to normal.</p><p><b>CONCLUSION</b>Resveratrol could promote the recovery of spermatogenesis after 2,5-HD-induced testicular injury.</p>

Protective effect of mouse 2.5s nerve growth factor on PC12 cells from injury induced by 2, 5-hexanedione / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore whether the nerve growth factor has protective effects on PC12 cells from injury induced by 2, 5-hexanedione.</p><p><b>METHODS</b>With PC12 cells as the model of neurons, different concentrations of NGF were added into the culture of PC12 cells. Then cell viability was tested with MTT. The DNA fragment was observed with agarose gel electrophoresis. The apoptosis ratio was tested with flow cytometry (FACS). The p53 protein was detected with western blot. The differences among the groups were compared.</p><p><b>RESULTS</b>Cell viabilities were increased with the increase of the concentrations of NGF (P < 0.05). The DNA fragment, the apoptosis ratio and the expression of p53 were all decreased with the increase of the concentrations of NGF (P < 0.05).</p><p><b>CONCLUSION</b>The NGF might have direct nutritional effects on PC12 cells, and protect them from injury induced by 2, 5 HD. Moreover, it might also have anti-apoptosis effect to some extent.</p>

Effect of 2, 5-hexanedione on calcium homeostasis of motor neuron / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the mechanism of cytotoxic effect of 2, 5-hexanedione (2, 5-HD) on motor neuron.</p><p><b>METHODS</b>Vsc4.1 (a cell line from motor neuron) was incubated with a series concentration of 2, 5-HD. The cell viability, Ca(2+) Mg(2+) ATPase and Na(+)K(+) ATPase were detected. Laser scanning confocal microscope (LSCM) was used for detecting intracellular calcium level. The average calcium level in VSC4.1 was measured by flow cytometry.</p><p><b>RESULTS</b>The cell viability was decreased when Vsc4.1 cells were treated with 2, 5-HD at the dosage of 2.5, 5.0, 7.5, 10, 15 and 20 mmol/L for 24 hours. Compared with the control group the activity of Ca(2+) Mg(2+) ATPase was decreased to 70.02%, 77.44% and 47.47% respectively; the activity of Na(+)K(+) ATPase was decreased to 82.07%, 72.45% and 50.71%. The difference was significant. Intracellular free calcium of VSC4.1 cell was increased rapidly within 10 s and then recovered within 40 seconds when it was exposed to 33.5 mmol/L 2, 5-HD. An increase in intracellular calcium was observed when the VSC4.1 was treated with 33.5 mmol/L 2, 5-HD. The peak of intracellular calcium level occurred ten minutes later.</p><p><b>CONCLUSION</b>The disturbance of calcium homeostasis may be involved in the mechanisms of neurotoxicity of 2, 5-HD.</p>

Induction of rat neural stem cells into oligodendrocyte precursor cells / 生理学报

We have previously established a culture method to isolate and cultivate neural stem cells (NSCs) derived from the rat embryonic brain and spinal cord. In the present study, we demonstrate that the spinal cord-derived NSCs can be induced to differentiate into oligodendrocyte precursor cells (OPCs) with a combined treatment composed of (1) conditioned medium collected from B104 neuroblastoma cells (B104CM) and (2) basic fibroblast growth factor (bFGF, 10 ng/ml). After induction, over 95% of the cells displayed bipolar or tri-polar morphology and expressed A2B5 and platelet derived growth factor receptor-alpha (PDGFR-alpha), markers that are specific for OPCs. Among PDGFR-alpha positive OPCs, only a few cells expressed glia fibrillary acidic protein (GFAP) and none expressed beta-tubulin III. In the presence of B104CM and bFGF, OPCs proliferated rapidly, formed spheres, expanded for multiple passages, and maintained their phenotypic properties. Upon withdrawal of B104CM and bFGF, these cells differentiated into either O4/GlaC-positive oligodendrocytes (OLs) or GFAP- and A2B5-positive type-2 astrocytes. Our results indicate that NSCs can be induced to differentiate into OPCs that possess properties of self-renewal and differentiation into oligodendrocytes and type-2 astrocytes, a property similar to that of O-2A progenitor cells. The OPCs can be maintained in an undifferentiated state over multiple divisions as long as both B104CM and bFGF are present in the medium. Thus, large quantity of OPCs can be obtained through this method for potential therapeutical interventions for various neurological degenerative diseases.