Effect of melatonin on the pyroptosis of hippocampus in neonatal rats with hypoxic-ischemic brain damage / 中华实用儿科临床杂志

ABSTRACT

Objective:To study the effect of melatonin (MEL) on the pyroptosis of hippocampus in neonatal rats with hypoxic-ischemic brain damage (HIBD), and the related mechanism.Methods:The animal model of HIBD was established by the modified Rice method.According to the random number table, a total of 105 Sprague-Dawley (SD) rats aged 7 days were divided into 7 groups (15 rats in each group) sham operation (Sham) group, model (HIBD) group, MEL treatment group (5, 10 and 20 mg/kg), phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway inhibitor (LY294002) treatment group and MEL+ LY294002 group.The hippocampus neuronal morphology and the changes of nissl bodies were observed through HE staining and nissl staining.The mRNA expression levels of Nod-like receptor family 3 (NLRP3), apoptosis-associated speck-like protein containing a card (ASC), Caspase-1, gasdermin D (GSDMD), interleukin-1β (IL-1β) and interleukin-18 (IL-18) in the left hippocampus of rats were detected by real-time fluorescence quantitative PCR.The protein expression level of the above indexes and the level of phosphorylated Akt (p-Akt) were measured by Western blot.Results:Compared with the Sham group, the number of cell layers in hippocampal CA1 region in the HIBD group decreased, the cell arrangement was irregular, and there were less nissl bodies.Besides, the mRNA expression levels of NLRP3 (1.98±0.08 vs.0.86±0.13), ASC (1.40±0.12 vs.0.81±0.07), Caspase-1 (1.46±0.10 vs.0.75±0.09), GSDMD (1.35±0.10 vs.0.81±0.10), IL-18 (1.23±0.08 vs.0.23±0.04), IL-1β (1.83±0.09 vs.0.57±0.08) and p-Akt (1.12±0.12 vs.0.54±0.07) in the HIBD group were significant higher than those in the Sham group (all P<0.05). Compared with the HIBD group, there were more cell layers in hippocampal CA1 region of the MEL group (10 mg/kg), the arrangement of cells was more regular, and the number of nissl bodies increased.The mRNA expression levels of NLRP3 (1.04±0.10), ASC (0.91±0.06), Caspase-1 (0.63±0.06), GSDMD (1.01±0.09), IL-18 (0.65±0.05) and IL-1β (0.63±0.10) in the MEL group were statistically significantly lower than those in the HIBD group (all P<0.05). Compared with the MEL group (10 mg/kg), the arrangement of cells in hippocampal CA1 region of the MEL+ LY294002 group was relatively disordered, the nissl bodies declined, the p-Akt protein level (0.87±0.09 vs.1.99±0.27) decreased significantly, and the Caspase-1(p20) protein level (0.85±0.09 vs.0.58±0.09) increased significantly (all P<0.05). Conclusions:MEL may inhibit the hippocampal pyroptosis in neonatal rats with HIBD by activating the Akt signaling pathway, thereby protecting the brain.