Lulu Jiang

Involvement of decreased neuroglobin protein level in cognitive dysfunction induced by 1-bromopropane in rats

1-Bromopropane (1-BP) is used as a substitute for ozone-depleting solvents (ODS) in industrial applications. 1-BP could display central nervous system (CNS) neurotoxicity manifested by cognitive dysfunction. Neuroglobin (Ngb) is an endogenous neuroprotectant and is predominantly expressed in the nervous system. The present study aimed to investigate Ngb involvement in CNS neurotoxicity induced by 1-BP in rats. Male Wistar rats were randomly divided into 5 groups (n=14) and treated with 0, 100, 200, 400 and 800 mg/kg bw 1-BP, respectively, by gavage for consecutive 12 days. Rats displayed cognitive dysfunction dose-dependently through Morris water maze (MWM) test. Significant neuron loss in layer 5 of the prelimbic cortex (PL) was observed. Moreover, 1-BP decreased Ngb protein level in cerebral cortex and Ngb decrease was significantly positively correlated with cognitive dysfunction. Glutathione (GSH) content, GSH/oxidized glutathione (GSSG) ratio and glutamate cysteine ligase (GCL) activity decreased in cerebral cortex, coupled with the increase in GSSG content. GSH and GSH/GSSG ratio decrease were significantly positively correlated with cortical Ngb decrease. Additionally, levels of N-epsilon-hexanoyl-lysine (HEL) and 4-hydroxy-2-nonenal (4-HNE) modified proteins in cerebral cortex of 1-BP-treated rats increased significantly. In conclusion, it was suggested that 1-BP resulted in decreased endogenous neuroprotectant Ngb in cerebral cortex, which might play an important role in CNS neurotoxicity induced by 1-BP and that 1-BP-induced oxidative stress in cerebral cortex might partly be responsible for Ngb decrease.

Acrylamide Retards the Slow Axonal Transport of Neurofilaments in Rat Cultured Dorsal Root Ganglia Neurons and the Corresponding Mechanisms.

Chronic acrylamide (ACR) exposure induces peripheral-central axonopathy in occupational workers and laboratory animals, but the underlying mechanisms remain unclear. In this study, we first investigated the effects of ACR on slow axonal transport of neurofilaments in cultured rat dorsal root ganglia (DRG) neurons through live-cell imaging approach. Then for the underlying mechanisms exploration, the protein level of neurofilament subunits, motor proteins kinesin and dynein, and dynamitin subunit of dynactin in DRG neurons were assessed by western blotting and the concentrations of ATP was detected using ATP Assay Kit. The results showed that ACR treatment results in a dose-dependent decrease of slow axonal transport of neurofilaments. Furthermore, ACR intoxication significantly increases the protein levels of the three neurofilament subunits (NF-L, NF-M, NF-H), kinesin, dynein, and dynamitin subunit of dynactin in DRG neurons. In addition, ATP level decreased significantly in ACR-treated DRG neurons. Our findings indicate that ACR exposure retards slow axonal transport of NF-M, and suggest that the increase of neurofilament cargoes, motor proteins, dynamitin of dynactin, and the inadequate ATP supply contribute to the ACR-induced retardation of slow axonal transport.

Identify Melatonin as a Novel Therapeutic Reagent in the Treatment of 1-Bromopropane(1-BP) Intoxication.

Abstract 1-Bromopropane (1-BP) has been used as an alternative for fluoride compounds and 1-BP intoxication may involve lung, liver, and central neural system (CNS). Our previous studies showed that 1-BP impaired memory ability by compromising antioxidant cellular defenses. Melatonin is a powerful endogenous antioxidant, and the objective of this study was to explore the therapeutic role of melatonin in the treatment of 1-BP intoxication. Rats were intragastrically treated with 1-BP with or without melatonin, and then sacrificed on 27th day after 1-BP administration. The Morris water maze (MWM) test was used to evaluate the spatial learning and memory ability of the experimental animals, and NeuN staining was performed to assess neuron loss in hippocampus. We found that rats treated with 1-BP spent more time and swam longer distance before landing on the hidden platform with a comparable swimming speed, which was markedly mitigated by the pretreatment with melatonin in a concentration-dependent manner. In addition, 1-BP-induced notable decrease in neuron population in hippocampus by promoting apoptosis, and melatonin pretreatment attenuated those changes in brain. The GSH/GSSG ratio was proportionately decreased and heme oxygenase 1 was increased in the rats exposed to 1-BP (Figure 6), and administration of melatonin restored them. Meanwhile, MDA, the level of lipid peroxidation product, was significantly increased upon exposed to 1-BP, which was significantly attenuated by melatonin pretreatment, indicating that administration of 1-BP could interfere with redox homeostasis of brain in rat, and such 1-BP-induced biomedical changes were reversed by treatment with melatonin. We conclude that treatment with melatonin attenuates 1-BP-induced CNS toxicity through its ROS scavenging effect.

Diallyl sulfide protects against lipopolysaccharide/d-galactosamine-induced acute liver injury by inhibiting oxidative stress, inflammation and apoptosis in mice

The effects of diallyl sulfide (DAS) and the potential mechanisms were investigated on lipopolysaccharide (LPS)/d-galactosamine (D-GalN)-induced acute liver injury in mice. DAS (50, 100, 200 μmol/kg) were orally given 1 h prior to LPS (10 μg/kg)/D-GalN (500 mg/kg) intraperitoneal injection. Serum and liver were collected at 8 h after LPS/D-GalN treatment. DAS Pretreatment reduced the activities of serum aminotransferase and attenuated histopathological damage in LPS/D-GalN-induced liver injury. Additionally, LPS/D-GalN-induced liver oxidative stress was ameliorated by DAS pretreatment, as evidenced by the decreased content of MDA and increased level of GSH, SOD, CAT in liver. Moreover, LPS/D-GalN-induced the excessive levels of TNF-α, IL-1β and MCP-1 in serum and liver was decreased by DAS pretreatment. Furthermore, DAS pretreatment attenuated LPS/D-GalN-induced hepatocyte apoptosis, as evidenced by TUNEL staining and protein expression of cleaved caspase3, Bax and Bcl-2 in liver. DAS also up-regulated the expression of p-PI3K p85 and p-Akt in a dose-dependent manner, and Akt inhibitor MK-2206 weakened the inhibitory effect of DAS on hepatocyte apoptosis induced by LPS/D-GalN. In conclusion, the results suggest that DAS exerts the protective effect on LPS/GalN-induced acute liver injury, and this effects possibly by suppressing oxidative stress, inflammation and regulating hepatocyte apoptosis via the PI3K/Akt pathway.

The protective effect of diallyl trisulfide on cytopenia induced by benzene through modulating benzene metabolism

It has been known that metabolism of benzene is necessary for its toxicity. The purpose of our study is to investigate the effect of diallyl trisulfide (DATS) on attenuating cytopenia in peripheral blood introduced by benzene through regulating benzene metabolism in rats. We established benzene poisoning model with benzene (1.3 g/kg), while the DATS treatment groups were treated with DATS plus benzene (15 or 30 mg/kg) for 28 days, respectively. The results of blood parameters and concentration of metabolites of benzene (t, t-MA and SPMA) determination in urine showed that DATS could effectively attenuate the cytopenia induced by benzene through regulating benzene metabolism. Western blot and chemical method were used to detect the activities and protein expression levels of enzymes CYP2E1 and GSTT1 in liver and enzymes MPO and NQO1 in bone marrow were tested. The results suggested that the inhibition of bioactivation in liver and bone marrow catalyzed by CYP2E1 and MPO and the activation of detoxification catalyzed by GSTT1 and NQO1 might be the critical mechanism, through which DATS modulated benzene metabolism to prevent benzene-induced cytopenia.

Docosahexaenoic Acid Protects against 1-Bromopropane Induced Cognitive Deficits in Rats involving in GSK-3β Activation and Oxidative Stress Inhibition

A number of organic solvent are known to be neurotoxic substance, which can cause neurotoxicological effects in humans. 1-Bromopropane (1-BP) is an alternative to ozone-depleting solvent that widely used in industrial production. Occupational exposure to 1-BP becomes a major health concern due to its neurotoxicity displayed in animals and humans. Docosahexaenoic acid (DHA), long chain n-3 polyunsaturated fatty acids (PUFA) and the main component of fish oil, is essential for normal neurological development and displays potent neuroprotective capacity. Here we investigate the protective effects and underlying mechanisms of DHA against 1-BP-induced deficits of spatial learning and memory ability in rats. Cognitive performance was assessed by Morris Water Maze test (MWM). Neuronal injury was determined by Nissl staining and TUNEL staining. The apoptosis-related proteins, including cleaved caspase-3, Bcl-2 and Bax, and proteins modified by 4-hydroxy-2-nonenal (4-HNE) or acrolein, in the brain were determined by Western blot. The inactive glycogen synthase kinase-3β (GSK-3β) in the brain of rats was also detected by specific antibody. Exposure to 1-BP resulted in learning deficits and memory loss of rats, neuronal apoptosis in the hippocampus cornu ammonis 3 (CA3) and prefrontal cortex, accompanied with significant GSK-3β inhibition by phosphorylation. Importantly, we found that pre-treatment with DHA significantly improved MWM performances of rats intoxicated with 1-BP, as well as the abrogation of neuron loss, alleviation of redox unbalance and GSK-3β activation in the brain. Our findings suggested that DHA supplementation would be a promising intervention for the central neurotoxicity of 1-BP, which might be correlated with oxidative stress and GSK-3β inhibition.