[The role of malic enzyme 1 regulating ferroptosis on nerve impairment of hypertensive mice following lead exposure].

Objective: To explore the role of hippocampal ferroptosis on nerve impairment of hypertensive mice following lead exposure, and to further explore the role of malic enzyme 1 (ME1) on hippocampal ferroptosis of hypertensive mice following lead exposure. Methods: In January 2024, 62 SPF-grode male C57 mice were selected, among which 32 mice were intraperitoneally injected with angiotensin Ⅱ (AngⅡ, 0.5 mg/kg) for 7 consecutive days to establish the hypertensive mice model. Then, hypertensive mice were randomly divided into hypertension group and Pb+hypertension group, and non-hypertensive mice were randomly divided into control group and Pb group, with 15 mice in each group. Mice in the hypertension group and the Pb+hypertension group were intraperitoneally injected with AngⅡ (0.5 mg/kg) once every two days, and the other two groups were intraperitoneally injected with equal amount of normal saline. Mice in the Pb group and the Pb+hypertension group were given 250 mg/L lead acetate solution, and the other two groups were given the drinking water for 8 weeks. Morris water maze test was applied to detect the cognitive function of mice. Western blotting was used to detect the expression of soulte corrier family 7 member A11 (SLC7A11), glutathione peroxidase 4 (GPX4) and ME1 protein. The contents of Fe(2+), malodialdehyde (MDA) and glutathione (GSH) were measured by corresponding assay kits. The HT22 survival rate was detected by CCK-8 assay. Plasmid transfection technique was used to overexpress ME1 gene in HT22 cells. To construct the ME1-overexpressing HT22 cell model, plasmid transfection was performed. Following verification of transfection efficiency with qPCR, ferroptosis was evaluated in all cell groups after toxicant exposure. Analysis of variance was used for comparisons among group, and the LSD-t test was used for pairwise comparisons. Results: Compared with the control group, the mice in Pb group and hypertension group showed significantly lower escape latency and fewer platform crossings (P<0.05). Moreover, the Pb+hypertension group exhibited further significant reductions in these measures compared to either the mice in Pb group or hypertension groupalone (P<0.05). The contents of Fe(2+) and MDA in hippocampus of Pb+hypertension group were significantly higher than that of hypertension group and Pb group (P<0.05). Meanwhile, the content of GSH and the expression levels of SLC7A11 and GPX4 protein were significantly decreased compared with that of hypertension group and Pb group (P<0.05). The exposure of lead and AngⅡ can aggravate the ferroptosis of HT22 cells. At the same time, the treatment of Fer-1 can increased cell survival rate caused by the exposure of lead and AngⅡ (P<0.05). ME1 protein expression decreased in the hippocampal tissue of mice in Pb+hypertension group and HT22 cells. Overexpression of the ME1 gene rescues ferroptosis in HT22 cells exposed to lead and AngⅡ. This is manifested by a decrease in Fe(2+) and MDA content, as well as an increase in GSH content and the protein expression of SLC7A11 and GPX4 (P<0.05) . Conclusion: Hypertension may aggravate hippocampal ferroptosis in mice with lead exposure through ME1 regulating NADPH, further exacerbating nerve impairment.