环境与职业医学 (Oct 2022)
Effect of GSK-3β-mediated DRP1 on inhibition of primary hippocampal neuronal growth induced by aluminum
Abstract
BackgroundAluminum (Al) can cause irreversible damage to neurons and synapses function, and the mechanism may be connected to mitochondrial damage caused by glycogen synthase kinase-3β (GSK-3β) regulating dynamin-related protein 1 (DRP1), resulting in inhibition of the growth of neuronal protrusions.ObjectiveTo investigate the role of GSK-3β regulating DRP1 in the inhibition of primary hippocampal neurite growth induced by Al.MethodsNeurons were extracted from the hippocampus of newborn mice (≤24 h old) for primary culture. On day 6, the purity of neurons was detected by immunofluorescence. On day 10, neurons with good growth state were selected for Al exposure and GSK-3β inhibitor SB216763 (SB) intervention. The experiment design included a blank control group, a dimethyl sulfoxide (DMSO) group, an Al (20 μmol·L−1) group, a SB (1 μmol·L−1) group, and a SB (1 μmol·L−1) + Al (20 μmol·L−1) group. After primary hippocampal neurons were treated with Al or SB for 48 h, cell viability was detected by CCK-8 assay, the mitochondrial morphology of primary hippocampal neurons was observed by transmission electron microscopy, the total protrusion length of primary hippocampal neurons was scanned and analyzed by laser confocal imaging, and their complexity was analyzed by Sholl analysis. The expression levels of phospho-GSK-3β, GSK-3β, and DRP1 were detected by Western blotting.ResultsThe immunofluorescent results showed that the purity of primary neurons was higher than 90%. After the Al exposure and the SB intervention for 48 h, compared with the blank control group, there was no obvious difference in cell viability in the DMSO group and the SB group (P>0.05), and the Al group showed reduced cell viability (P=0.006); there was no obvious difference in cell viability between the SB+Al group and the Al group (P>0.05). Compared with the blank control group, there was no obvious difference in the average total length of protrusion in the DMSO group and the SB group (P>0.05), and the Al group showed reduced average total length of neurite (P0.05), and that in the Al group was significantly reduced (P0.05). The mitochondrial structure of the blank control group was complete and the crest was clearly visible; there was no apparent variation in the mitochondrial structure in the DMSO group and the SB group; the mitochondria in the Al group were vacuolated and the crista disappeared; the SB+Al group showed clearer crista than the Al group. The difference in GSK-3β phosphorylation level among groups was statistically significant (F=45.841, P0.05), increased in the SB group (P=0.022), and significantly reduced in the Al group (P0.05), and significantly increased in the Al group (P=0.001); the DRP1 protein level in the SB+Al group was significantly lower than that in the Al group (P=0.029).ConclusionAl may increase the level of DRP1 protein by activating GSK-3β, causing mitochondrial damage and inhibiting neuronal protrusions growth.
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