Studies On Toxic Effect Of Lead Acetate And Antagonism N-acetyl Cysteine On Cerebral Cortical Neurons In Rats

To study lead (Pb) neurotoxicity mechanism on central nervous system, the model of experimental neurons which were obtained from the neonate Sprague—Dawley rats in 24h was established successfully. Toxic effect of lead on neuron's morphology, viability, apoptosis rate, the enzymatic activity changes of lipid peroxidation and protective effect of N-Acetyl Cysteine (NAC) were evaluated by the inverted light microscope, the scanning electron microscope, the fluorescence microscope,the flow cytometry (FCM),and adopting the Nissl's staining method, microculture tetrazolium assay(MTT) and related kits.The results were as follows: (1) The results of morphological analysis and viability measurement showed that the cortical neuron's viability was meridian, and they formed an integrated neural network on day 6 post-beginning of culturing. (2) To observe the neuron's morphological changes of lead acetate impairment, the neurons were exposed to different concentrations of lead groups( 0μmol/L Pb, 50μmol/L Pb, 100μmol/L Pb, 200μmol/L Pb, 400μmol/L Pb)and were incubated for 3h, 6h, 12h and 24h. The results indicated a significant decrease in pericaryons and processes after incubating 12 h (p﹤0.05). With prolonging of the culturing time and increasing concentrations of lead acetate, the inhibitory effect was enhanced gradually; (3) Neuron's survival rate, as determined by MTT, descended with different concentrations of lead acetate after culturing 12h.And it was a significantly decreased compare with the control group (p﹤0.05); (4) Neurons were treated by different concentrations of lead acetate for 12h. Then, they were lucifugal incubated with Hoechst 33258 in 5 min. The results revealed that the nucleus crimpled, crescent liked and chromatin condensed, even nucleus disintegrated. And apoptosis rate was higher than the control group by determination of flow cytometry; (5) In comparison with the control group, the activities of GSH-PX, SOD and TChE in neurons which were treated by lead acetate of different concentrations for 12h were significantly decreased(P﹤0.05). However, the activity of CAT and the content of MDA in neurons were significantly increased than that of the control group(P﹤0.05). (6) Compared NAC antagonistic groups with the poisoning groups, the former neuron's viability was significantly increased, especially which were treated with NAC for 24h. The apoptosis rate of neurons was degraded relative to the poisoning groups. Meanwhile, the activities of GSH-PX, SOD, TChE and CAT were increased accordingly, but the content of MDA was decreased compared with the poisoning groups.Conclusion: (1) Lead acetate can inhibit cortical neuron differentiation, which led to the pericaryon diminutus and process decurtation than the control group; (2) Neuron apoptosis what lead induced is one of possible mechanisms and displays a dose effect in comparison with the control group; (3) Lead acetate can result in oxidative stress and modify antioxidative enzyme activity. Therefore, lipid peroxidation is also one of mechanisms of lead neurotoxicity; (4) NAC inhibits the oxidative damage of lead. The data indicated that NAC could increase antioxidative effects and reduce lipid peroxidation in neurons of SD rats in vitro.