Dl-3-n-butylphthalide improves intestinal microcirculation disorders in septic rats by regulating the PI3K/AKT signaling pathway and autophagy.

Purpose: Sepsis has complex pathophysiological mechanisms that bring new challenges in the treatment of sepsis at a time when the intestinal microcirculation in sepsis is receiving increasing attention. Dl-3-n-butylphthalide (NBP), which is a drug that can improve multiorgan ischemic diseases, is also worth examining to improve the intestinal microcirculation in sepsis.

Methods: In this study, male Sprague-Dawley rats were divided into the sham group (n = 6), CLP group (n = 6), NBP group (n = 6) and NBP + LY294002 group (n = 6). The rat model of severe sepsis was established by cecal ligation and puncture (CLP). Abdominal wall incisions and sutures were performed in the first group, and CLP was performed in the latter three groups. Normal saline/NBP/NBP + LY294002 solution was injected intraperitoneally 2 h or 1 h before modeling. Hemodynamic data (blood pressure and heart rate) were recorded at 0, 2, 4 and 6 h. Sidestream dark field (SDF) imaging and the Medsoft System were used to observe the intestinal microcirculation of rats and obtain data at 0, 2, 4, and 6 h. Six hours after the model was established, the serum levels of TNF-α and IL-6 were measured to evaluate the level of systemic inflammation. Pathological damage to the small intestine was evaluated by electron microscopy and histological analysis. The expression levels of P-PI3K, PI3K, P-AKT, AKT, LC3 and p62 in the small intestine were analyzed by Western blotting. The expressions of P-PI3K, P-AKT, LC3 and P62 in small intestine were detected by immunohistochemical staining.

Results: NBP improved intestinal microcirculation disturbances in septic rats, alleviated the systemic inflammatory response, reduced the destruction of the small intestinal mucosa and the disruption of microvascular endothelial cells, and alleviated autophagy in vascular endothelial cells. NBP increased the ratio of P-PI3K/total PI3K, P-AKT/total AKT, and P62/β-actin and decreased the ratio of LC3 II/LC3 I.

Conclusion: NBP ameliorated intestinal microcirculation disturbances and the destruction of small intestinal vascular endothelial cells in septic rats by activating the PI3K/Akt signaling pathway and regulating autophagy.