Shi S, Cui Q, Xu J, Tang Z, Shi B, Liu Z. Baicalin Suppresses Bilirubin-Induced Apoptosis and Inflammation by Regulating p38 Mitogen-Activated Protein Kinases (MAPK) Signaling in Neonatal Neurons.
Med Sci Monit 2020;
26:e926441. [PMID:
32633271 PMCID:
PMC7366788 DOI:
10.12659/msm.926441]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Background
Hyperbilirubinemia is associated with central nervous system damage in preterm neonates due to the neurotoxicity of bilirubin. This study explored the possible mechanisms of bilirubin’s neurotoxicity, and the protective effect of baicalin (BAI) was also investigated.
Material/Methods
Isolated neonatal rat hippocampal neurons were exposed to free bilirubin (Bf). BAI was used to treat these neurons. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the cell viability. Terminal deoxynucleotidyl transferase-dUTP nick-end labeling (TUNEL) assay was used to detect apoptosis. Contents of inflammatory cytokines were determined by enzyme-linked immunosorbent assay (ELISA). Protein expression and phosphorylation levels were assessed by Western blotting. Nuclear translocation was observed by immunofluorescent staining.
Results
Bf incubation significantly induced apoptosis and decreased viabilities of neurons. The phosphorylation levels of MAP kinase kinase (MKK)3, MKK6, p38 mitogen-activated protein kinases (MAPK), nuclear translocation level of p65, and the expression levels of cleaved caspase3 and tumor necrosis factor (TNF)α were found to be dramatically higher in Bf-incubated neurons. BAI pre-treatment, however, increased cell viability by reducing cell apoptosis. BAI pre-treatment also reduced phosphorylation levels of MKK3, MKK6, p38 MAPK, and nuclear translocation level of p65, as well as the expression levels of cleaved caspase3 and TNFα, in Bf-incubated neurons.
Conclusions
BAI suppressed bilirubin-induced neuron apoptosis and inflammation by deactivating p38 MAPK signaling.
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