Effects of terlipressin on blood pressure and survival in septic mice following trauma and its mechanism

Abstract

To investigate the effects of terlipressin (TP) on blood pressure and survival in septic mice following trauma and its mechanism. (1) Survival experiment: 120 male C57BL/6 mice aged 6-8 weeks were enrolled, the posttraumatic sepsis mice model was reproduced by traumatic hemorrhage (bilateral femoral fracture + 45% of total blood loss) followed by cecal ligation and puncture (CLP) after 8 hours. Intraperitoneal injection of TP was used for intervention. Sixty model mice were used to observe the effect of 0.05 μg/g TP at different intervention times (the drug was given immediately after traumatic hemorrhage + the administration was repeated after 6 hours, the drug was given immediately after traumatic hemorrhage + the administration was repeated every 6 hours until the end of the experiment, the drug was given at 4 hours after CLP + the administration was repeated every 6 hours until the end of the experiment) on 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention time of TP. The other 60 model mice were used to observe the effect of different TP intervention doses (0.01, 0.05, 0.25 μg/g) at the best intervention time on the 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention dose of TP. (2) Intervention experiment: the other 45 mice were enrolled, and they were randomly divided into traumatic hemorrhage + sham group (TH+sham group, only laparotomy without CLP), TH+CLP group, and TH+CLP+TP group (the best intervention time and dose of TP shown by survival experiment were used), with 15 mice in each group. Mean arterial pressure (MAP) of mice was monitored continuously. The orbital whole blood was collected at 2 hours after successful reproduction of the model, and the lung tissues were harvested at 12 hours and 24 hours, respectively. The pathological changes in lung tissue were observed with light microscope. The contents of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in serum and lung tissue were determined by enzyme linked immunosorbent assay (ELISA). The expressions of IL-1β and TNF-α mRNA in lung tissue were determined by real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The expressions of nuclear factor-κB p65 (NF-κB p65) in the nucleus and cytoplasm of lung tissue were determined by Western Blot. (1) Survival experiment results showed that the 48-hour cumulative survival rate of mice was highest with TP intervention by 0.05 μg/g administration immediately after traumatic hemorrhage and repeated every 6 hours, which was the best intervention method of TP. (2) Intervention experiment results showed that the pulmonary alveolar wall fracture accompanied by inflammatory cell infiltration was found at 12 hours after the successful reproduction of traumatic sepsis model, and the pathological damage was gradually increased with time prolongation. MAP was decreased sharply after traumatic hemorrhage, and it was continued to decrease after two-hit of CLP. The contents of IL-1β and TNF-α in serum and lung tissue, the expressions of IL-1β and TNF-α mRNA in lung tissue, and expressions of NF-κB p65 protein in cytoplasm and nucleus of TH+CLP group were significantly higher than those in TH+sham group. Compared with TH+CLP group, the pathological changes in lung tissue were improved significantly, and the MAP was decreased gently after TP intervention, the levels of inflammatory mediators in serum were significantly decreased [IL-1β (pg/L): 164.32±25.25 vs. 233.11±23.02, TNF-α (pg/L): 155.56±31.47 vs. 596.38±91.50, both P < 0.05], and their expressions in lung tissue [IL-1β content (ng/mg): 262.68±16.56 vs. 408.15±17.85, IL-1β mRNA (2-Δ ΔCt): 2.63±0.68 vs. 6.22±0.74; TNF-α content (ng/mg): 311.07±17.35 vs. 405.04±24.83, TNF-α mRNA (2-Δ ΔCt): 2.04±0.62 vs. 5.32±0.55, all P < 0.01], and NF-κB p65 protein expressions were significantly down-regulated (gray value: 0.47±0.01 vs. 1.28±0.05 in cytoplasm, 0.45±0.02 vs. 1.95±0.06 in nucleus, both P < 0.01]. The continuous intervention with TP 0.05 μg/g administration immediately after traumatic hemorrhage and repeated every 6 hours could improve the MAP of mice with traumatic sepsis, and improve the prognosis. The mechanism may be related to alleviating the inflammatory response and inhibiting the activation of the NF-κB signaling pathway in the lung tissue.