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>

Changes in autophagy-related protein levels in nervous tissues of hens with tri-ortho-cresyl phosphate-induced delayed neuropathy / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the changes in the levels of autophagy-related proteins, Atg1, Atg5, and Beclin1, in organophosphate-induced delayed neuropathy (OPIDN) caused by tri-ortho-cresyl phosphate (TOCP), and to investigate the molecular pathogenic mechanism of OPIDN.</p><p><b>METHODS</b>Thirty adult Roman hens were randomly and equally divided into control group and 1, 5, 10, and 21 d intoxication groups. Each hen in the intoxication group was administered TOCP by gavage at a single dose of 750 mg/kg, while each hen in the control group was administered the same volume of corn oil. The hens were killed at the corresponding time points, and their tibial nerves and spinal cords were collected. The levels of Atg1, Atg5, and Beclin1 in the tibial nerves and spinal cords were measured by immunoblotting.</p><p><b>RESULTS</b>Compared with those in the control group, the levels of Atg1 in tibial nerves decreased by 29.8%, 64.4%, 43.5%, and 19.8% at 1, 5, 10, and 21 d, respectively, after intoxication ((P < 0.05); the levels of Atg5 in tibial nerves decreased by 36.8%, 49.6%, 51.2%, and 31.5% at 1, 5, 10, and 21 d, respectively, after intoxication (P < 0.05); the levels of Beclin1 in tibial nerves decreased by 68.5%, 66.3%, and 32.2% at 1, 5, and 10 d, respectively, after intoxication (P < 0.05). Compared with those in the control group, the levels of Atg1 in spinal cords decreased by 23.5%, 48.7%, and 20% at 1, 5, and 10 d, respectively, after intoxication (P < 0.05); the levels of Atg5 in spinal cords decreased by 32.7%, 51.5%, 47.3%, and 39.6% at 1, 5, 10, and 21 d, respectively, after intoxication (P < 0.05); the levels of Beclin1 in spinal cords decreased by 28.9%, 50.2%, 43.2%, and 28.3% at 1, 5, 10, and 21 d, respectively, after intoxication (P < 0.05).</p><p><b>CONCLUSION</b>The intoxication of TOCP is associated with the significant changes in the levels of autophagy-related proteins in the nervous tissues of hens, which might be involved in the pathogenesis of OPIDN.</p>

Effect of phenylmethylsulfonyl fluoride pretreated on neurofilament subunits in spinal cords of hens administrated with tri-o-cresyl phosphate / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the dynamic changes of neurofilaments (NFs) proteins in spinal cords of hens with phenylmethylsulfonyl fluoride (PMSF) pretreatment for exploring the mechanism of tri-o-cresyl phosphate (TOCP)-induced delayed neuropathy (OPIDN).</p><p><b>METHOD</b>Adult Roman hens were randomly divided into three groups, control, TOCP and PMSF + TOCP. Birds in PMSF + TOCP set were pretreated with PMSF, 24 hours later, hens in both TOCP group and PMSF + TOCP group were administrated with TOCP at a single dosage of 750 mg/kg. Then all animals were sacrificed on the corresponding time-points of 1, 5, 10, and 21 days respectively after dosing of 750 mg/kg TOCP. The spinal cords were dissected, homogenized, and centrifuged at 100,000 x g. The levels of high molecular neurofilament (NF-H), medium molecular neurofilament (NF-M) and low molecular neurofilament (NF-L) in both pellet and supernatant fractions of spinal cords were determined by SDS-PAGE and Western-blotting.</p><p><b>RESULTS</b>The hens in TOCP group showed paralysis gait at the end of 21-day experimental period. The levels of NFs proteins in spinal cords changed obviously. Compared with control, the NFs in pellet showed a dramatic decrease on day 10 and then followed by a recovery. In the supernatant, the NFs proteins showed similar changes, which decreased significantly on day 10 and almost recovered control on day 21. Such as, NF-L, NF-M and NF-H decreased by 51%, 86% and 38% on day 10. The OPIDN signs were not observed in PMSF + TOCP group, and imbalances of NFs were obviously alleviated. Compared with control, only NF-M in pellet increased by 21% (P < 0.05) on day 21, others remained no changes; The levels of NF-H and NF-M in supernatant respectively increased by 19% and 35% on day 21, others were no significant statistical differences.</p><p><b>CONCLUSION</b>TOCP may induce imbalance of NFs levels in progress of OPIDN, and PMSF pretreatment may protect animals from OPIDN by reducing above changes, which may explain that TOCP-induced imbalance of NFs may be connected with the occurrence and development of OPIDN.</p>

Protective effect of garlic oil given at different time against acute liver injury induced by CCl4 / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To observe and compare the protective effect of garlic oil against carbon tetrachloride (CCL)-induced acute liver injury.</p><p><b>METHODS</b>The experiments include 4 preventive groups and 2 therapeutic groups. In every preventive and therapeutic group, the mice were randomized into 6 groups with 15 each, including one negative control group, one solvent control group, one CCl4 model group and 3 garlic oil groups (25, 50, and 100 mg/kg body weight). Before given a single gavage of CCl4 (80 mg/kg), the mice were pretreated with garlic oil by gavage in preventive group 1 (30 days, once daily), preventive group 2 (5 days, once daily), preventive group 3 (ahead of 2 h, once), preventive group 4 (immediately, once) or the vehicle (corn oil, 10 ml/kg) in solvent control group. In therapeutic groups, the mice were gavaged garlic oil 2 h (once, in therapeutic 1) or for 5 days (once daily, in therapeutic 2) after administration CCl. After 24 h of the last administration, blood was collected and centrifuged at 2500 r/min at 4 degrees C for 10 min, and serum was removed to measure ALT and AST activities. The liver was dissected, weighed to calculate the liver coefficient (relative liver weight). At the same time, the liver samples were studied by histological examinations.</p><p><b>RESULTS</b>Compared with negative group, the liver coefficient and the activities of ALT and AST in serum of model group were increased remarkably (P < 0.01). Compared with CCl model group, the liver coefficient and the activities of ALT and AST in serum were decreased significantly (P < 0.01) by garlic oil dose-dependently in each preventive group. Simultaneously, histological assessment showed that garlic oil effectively alleviated hepatocyte injuries induced by CCl4. Comparing the preventive effects of garlic oil in every group, it was better in preventive group 3 than others. However, all indexes and histological examinations in therapeutic group 1 did not show the difference with those of CCl4 model group. In therapeutic group 2, all indexes recovered after 5 d of CCl4 administration.</p><p><b>CONCLUSIONS</b>Garlic oil can prevent acute liver injury induced by CCl4 and the effect is better in ahead of 2 h group than others.</p>

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>

Alterations of microtubule and microfilament expression in spinal cord of carbon disulfide intoxicated rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate whether the alterations of microtubule and microfilament expression are responsible for the neurotoxicity of carbon disulfide.</p><p><b>METHODS</b>Wistar rats were administered with carbon disulfide by gavage at a dosage of 300 or 500 mg/kg for continuous 12 weeks (five times per week). Spinal cords of carbon disulfide-intoxicated rats and their age-matched controls were Triton-extracted and ultracentrifuged to yield a pellet and a corresponding supernatant fraction. Then, the contents of alpha-tubulin, beta-tubulin, and beta-actin in both fractions were determined by immunoblotting. In the meantime, their mRNA levels in spinal cords were quantified using reverse transcriptase-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>In the supernatant fraction, the contents of beta-tubulin and beta-actin in both treated groups increased significantly (P < 0.01) the content of beta-tubulin increased by 141% and 158% respectively, and the content of beta-actin increased by 19% and 32% respectively. In the pellet fraction, the content of beta-tubulin in both groups increased by 107%(P < 0.01) and 118%(P < 0.01) respectively, and the others keep unaffected. In the meantime, the levels of of mRNA expression of beta-tubulin and beta-actin gene were elevated consistently in CS(2)-treated groups (P < 0.01) the levels of mRNA expression of beta-tubulin increased by 207% and 212% respectively, and the levels of mRNA expression of beta-actin increased by 94% and 91% respectively.</p><p><b>CONCLUSION</b>Carbon disulfide intoxication results in alternations of microtubule and microfilament expression, and the alternations might be related to its neurotoxicity.</p>

Effect of carbon disulfide on oxidation-antioxidation function of rat nerve tissues / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of carbon disulfide (CS(2)) on oxidation-antioxidation function of rat nerve tissues.</p><p><b>METHODS</b>Thirty male Wistar rats were randomly divided into the control group, the low-dosage exposure group and the high-dosage group, 10 rats each. The rats of the two exposure groups were administered with CS(2) by gavage at a dosage of 300 or 500 mgxkg(-1)xd(-1), 5 times every week for continuous 12 weeks. The alterations in glutathione (GSH), malondialdehyde (MDA), reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), hydrogen peroxidase (CAT) and total anti-oxidation (T-AOC) in cerebrum, spinal cord, and sciatic nerve of CS(2)-treated animals were assayed.</p><p><b>RESULTS</b>The results showed that the contents of MDA and ROS in nerve tissues of CS(2)-treated groups increased significantly except ROS in spinal cord and sciatic nerve of low dose group. The content of MDA was increased by 20.7% and 33.6% respectively in the cerebrum of the rats of the low-dosage group and the high-dosage group, by 18.5% and 23.3% respectively in the spinal cord, and by 20.7% and 53.0% respectively in the sciatic nerve, The content of MOS was increased by 20.1% and 34.9% respectively in the cerebrum of the rats of the low-dosage group and the high-dosage group, and by 14.1% and 15.4% respectively in the spinal cord and the sciatic nerve of the rats of the high-dosage group (P < 0.05 or P < 0.01). Furthermore, the activities of SOD, GSH-Px, CAT and T-AOC decreased significantly except GSH-Px and SOD in cerebrum of low dose group. The content of GSH was decreased by 17.2% and 26.5% respectively in the cerebrum of the rats of the low-dosage group and the high-dosage group, by 26.4% and 31.2% respectively in the spinal cord, and by 15.1% and 20.0% respectively in the sciatic nerve. The content of T-AOC was decreased by 11.1 and 26.4% respectively in the cerebrum of the rats of the low-dosage group and the high-dosage group, by 15.1% and 38.4% respectively in the spinal cord, and by 35.6% and 42.3% respectively in the sciatic nerve. The activity of SOD was decreased by 12.1% and 25.4% respectively in the spinal cord of the rats of the low-dosage group and the high-dosage group and by 16.4% and 30.3% respectively in the sciatic nerve. The activity of GSH-Px was decreased by 17.3% and 32.5% respectively in the spinal cord of the rats of the low-dosage group and the high-dosage group and by 17.1% and 21.5% respectively in the sciatic nerve. The activity of GSH-Px and SOD was decreased by 12.6% and 30.1% respectively in the cerebrum of the rats of the high-dosage group. The activity of CAT was decreased by 17.5% and 39.4% respectively in the cerebrum of the rats of the low-dosage group and the high-dosage group, by 25.2% and 31.3% respectively in the spinal cord, and by 17.1% and 36.9% respectively in the sciatic nerve (P < 0.05 or P < 0.01).</p><p><b>CONCLUSION</b>Subchronic exposure to CS(2) can induce significant changes of oxidation-antioxidation function in rat nerve tissues, which might be related to CS(2)-induced neurotoxicity.</p>