| Objective：To explore the role of autophagic mechanisms correlated toneuronal injury induced by lead exposure in hippocampus in young rats, andfurther to investigate the neuronal protective activity of autophagic inducertrehalose in this process.Methods：Young Wistar rats were divided into normal control group(Control), lead exposure group (PbE) and lead exposure combined withtrehalose intervention group (Tre+PbE). Based on different administrationperiod, each group was further divided into14d and21d two subgroups,respectively. There were6young rats in every subgroup. Lead exposure modelwas established by lead acetate via drinking water. PbE group was given0.2%lead acetate added in drinking water. Tre+PbE group was given the mixture of0.2%lead acetate and2%trehalose, while the control group drank normal water.Pups exposed to lead through breast milk of their mothers before weaned (P21),who were breed with0.2%lead acetate. When the pups could drink themselves,they drank the same water as their mothers. Rats were killed and detections werecarried out after they were administrated for14d and21d, respectively. Thenblood and brain lead content were tested, the expression of autophagic markerBeclin1and LC3B in hippocampus were evaluated using Western Blot method,the subcellular expression sites of these markers were located byimmunohistochemical method, the distribution of autophagic bodies inhippocampal neurons were observed by electron microscopy, HE staining underlight microscopy was used to evaluate the mortality of hippocampal neurons.Results：(1) Blood and brain lead concentration were significantly higher inPbE group and Tre+PbE group than that of Control group (P <0.05).(2) Immunohistochemical observation showed that the autophagic marker Beclin1and LC3B protein were mainly expressed in cytoplasm of hippocampal neurons.Western Blot found that Beclin1and LC3B increased significantly in Tre+PbEgroup than that of Control group after administrated for14d (P <0.05). LC3Bexpressed higher in Tre+PbE group than that of PbE group (P <0.05), also inPbE group than that of Control group (P <0.05). Beclin1was increased inTre+PbE group than that of PbE group, also in PbE group than that of Controlgroup. However, there were no significances（P>0.05）. Beclin1and LC3Bincreased significantly in Tre+PbE group than that of Control group afteradministrated for21d (P <0.05). Beclin1increased in Tre+PbE group than thatof PbE group, which was higher than Control group, but both of thecomparisons were not statistically significant (P>0.05). LC3B expression wasincreased in PbE group than Control group (P <0.05). LC3B increased inTre+PbE group than that of PbE group without statistical significance (P>0.05).(3) Autophagic bodies were observed in hippocampal neurons in PbE group, andwere found easily in Tre+PbE group, while were rare in Control group.(4)Morphological examinations of neurons by HE staining showed the deadneurons were higher in PbE group than that of Tre+PbE group (P <0.05), bothgroups were higher than Control group (P <0.05).Conclusion：Lead exposure may cause the increment of autophagy relatedprotein expression in hippocampus and promote the formation of autophagicbodies, suggesting that lead exposure can induce autophagy in hippocampalneurons. As the autophagic inducer trehalose can decrease the death rate ofhippocampal neurons via further enhancing the level of cellular autophagy, wespeculate that the autophagic response induced by lead exposure may play aneuronal protective role, and trehalose also has neuronal protective activitythrough strengthening the autophagic reaction induced by lead. Our findingssuggest that the neuronal death in hippocampus caused by lead exposure may be through apoptosis and/or necroptosis pathway, but not autophagy. |
PDF Full Text Request