| Perfluorooetane sulfonate, PFOS is a widespread environmental pollutant,with stable chemical properties and difficult to be degraded. PFOS was found to be potentially neurotoxicity, especially more sensitive to the developmental period of animals.Hippocamp-us is an important structure in the brain involved in learning and memory process. The dentate gyrus of hippocampus, one of the region in adult has neural stem cells, which can proliferate and differentiate into neurons and easily injured by external environment pollutents. As a results, neurogenesis is insufficient. At present, the PFOS neurotoxic damage mechanism is not yet clear and has no effective intervention for this. In recent years, exogenous neural stem cells, NSCs transplantation maybe a way for repairing neural injury and has attracted attention.Objective: To observe the effects of PFOS exposure on hippocampal formation and cognitive function in neonatal rats and to explore the potential intervention of exogenous neural stem cell transplantation.Methods:1. The preparation of the chronic exposure model of PFOS in neonatal rats and the observation of the effect on neural behavior and hippocampal tissue. The experimental animals were randomly divided into contral group and model group, 35 rats in each group. The model group rats were given 10mg/kg PFOS were injected intraperitoneally. The contral group were given the same amount of water 2%Tween-80 saline for 4 weeks. The weight, neurobehavioral changes were recorded. Meanwhile,with HE staining, morphological changes of the hippocampus were observed. 2. Intervention effect of NSCs transplantation on the neurotoxicity of PFOS. Intervention effect of exogenous NSCs transplantation on the neurotoxicity of PFOS. The ventricular tube membrane nerve stem cell of PND 1 SD rats were cultured and identified, for NSCs transplantation. The experimental animals were divided into: contral group, P10 group, P10+T group and T group, At the 1,2,4 week after transplantation, the body weights were recorded, the neurobehavioral changes were observed by water maze, Open-field tests., And at 4 weeks after transplantation, HE staining was used to detect the effect of NSCs transplantation on the hippocampus. Using western blot and q RT-PCR, a7n ACh R protein and m RNA level were invisitgated, The IL-1b in the serum was observed with ELISA and the levels of amino acids with HPLC in hippocampus.3. Study on the neurotoxicity mechanism of PFOS. The rats were divided into control group, low dose exposure P5 group(5 mg/kg PFOS group), high dose exposure P10 group(10 mg/kg PFOS group), 10 rats in each group treated for 4 weeks. After 4 weeks, using the Dot-blot technique to detection of inflammatory factors CINC-3, CNTF, IL-1b, IL-6, TNF-a changes; using western blot and q RT-PCR to detection of hippocampal Dmnt3 a, Ep C1, Suv420h2, Hdac8 protein and m RNA expression levels.Result: Experiment One:1 The effects of PFOS on general conditions in neonatal rats. The results showed that, the rats in model group appear gross faecal around the anus, stay lying, lethargy. Compared with the control group, model group rats showed slow growth in weight(P <0.05).2 The effects of PFOS on the neural behavior of neonatal rats. The escape latency was longer and the target quadrant residence time was shorter than that of the control group with dose dependent in model group. The time spent at center of enclosure was longer, vertical rearing was less, ambulatory distance was shorter, but no significant different performance in rotarod test between the two groups. 3 The effects of PFOS on hippocampus. The morphology of hippocampus in model rats showed that the neurons were blurring with nuclear pyknosis and the number of nerve cells in CA1 and the neural precursor cells in dentate gyrus were less than control group.Experiment Two:1 The effects of PFOS on general conditions in neonatal rats. The results show that the mental status of P10+T group rats showed improved, increased activity but the weight is no significant increase. 2 The effects of PFOS on the neural behavior of neonatal rats. The rats in P10+T group in the target quadrant residence time was longer, the central cell residence time significantly shorter than P10 group.3 The effects of NSCs transplantation on the hippocampus in rats. The results showed that the neurons morphology and arranged in a regular pattern in hippcampus in the P10+T group rats.4 The effects of NSCs transplantation on IL-1b in serum. The results showed that the P10 group rats of IL-1b level is higher than that of control group, Compared with the P10 group, P10+T group of serum IL-1b decreased signifycantly.5 The effects of NSCs transplantation on a7n ACh R of hippocampal. The results show that a7n ACh R protein and m RNA expression levels of P10 group were lower than control group(P﹤0.001),but were significantly elevated compared with P10 group(P﹤0.001). 6 The effects of NSCs transplantation on amino acids in hippocampus. The results showed that the content of glutamatiic acid in P10 group was lower than control group(P﹤0.05) and the P10+T group was higher than P10 group(P ﹤ 0.05). Experiment Three: 1 Effects of PFOS on proinflammatory cytokines in hippocampal tissue.The CINC-3, IL-6,CNTF,IL-1b and TNF-a in P5 group was higher than control group, also the P10 group was significantly increased. Meanwhile the CINC-3, CNTF, TNF-a in P10 group was higher than P5 group. 2 Effects of PFOS on Hdac8, Ep C1, Suv420h2 and Dmnt3a in the hippocampus tissues. The expression levels of Dmnt3 a protein in P5 group and P10 group were higher than control group,while Ep C1, Suv420h2 and Hdac8 protein were decreased. At the same time, the expression of Dmnt3 a protein in P10 group was significantly higher than P5 group, and Ep C1, Suv420h2, Hdac8 in P10 group were lower than that in P5 group.Conclusion:1 PFOS early exposure injury to the hippocampal tissue structure and cause spacial memory loss. 2 The neurotoxicity mechanism of PFOS exposure is related to the immune inflammatory reaction, the loss of neurons, the abnormality of epigenetic modification, and the disorder of amino acid metabolism in hippocampus. 3 The exogenous NSCs transplantation can improve the neurogenesis, increase the a7n ACh R expression of cholinergic neurons and inhibit the immune inflammatory reaction.in the hippocampus. |
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