Early Ascorbic Acid Administration Prevents Vascular Endothelial Cell Damage in Septic Mice
Abstract Background: Ascorbic acid (AsA) therapy for sepsis is thought to have a protective effect on vascular endothelial cells. However, the effect of AsA therapy on endothelial cell dysfunction over time and the appropriate timing for AsA administration to demonstrate efficacy is unclear.Methods: Septic mice were induced by cecal ligation and puncture (CLP). The effect of AsA administration (200 mg/kg) on vascular endothelial cell dysfunction in sepsis was examined using septic mice at two administration timings: early group (AsA was administered immediately after CLP) and late group (AsA was administered 12 h after CLP). First, survival rates were compared between the early and late administration groups. Next, the dihydrobiopterin/tetrahydrobiopterin (BH2/BH4) ratio, serum syndecan-1, and endothelial nitric oxide synthase (eNOS) were measured as indicators of vascular endothelial cell damage, and liver tissue was examined for organ damage to verify the effect of early AsA administration in septic mice.Results: In survival experiments, the early group showed significantly improved survival compared to the non-treatment group (p < 0.05), while the late group showed no improved survival compared to the non-treatment group. The BH2/BH4 ratio increased after 6 hours following CLP, and the increase was suppressed by early AsA administration (0.12 ± 0.02 vs. 0.07 ± 0.016, p < 0.05). Serum syndecan-1 levels were significantly elevated at 12 h after CLP, and early AsA administration prevented the increase (25.4 ± 12.1 vs. 9.9 ± 2.7 mg/ml, p < 0.05). The expression of eNOS at 12 h after CLP was decreased in the non-treatment group, but the expression was protected by early AsA administration. Moreover, hematoxylin and eosin staining of hepatocytes showed reduced liver damage in the early group compared to the non-treatment group.Conclusions: In septic mice, early AsA administration immediately after CLP may have protective effects on vascular endothelial cells by decreasing the BH2/BH4 ratio, resulting in reduced organ dysfunction and improved survival. To achieve this effect, early administration of AsA is required before BH4 is oxidized.