Date Published: September 16, 2019
Publisher: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Author(s): Caio César Chaves Costa, Nathalia Gabay Pereira, Anna Luiza Melo Machado, Mariana Albuquerque Dórea, Rafaella Macêdo Monteiro da Cruz, Renata Cunha Silva, Robson José de Souza Domingues, Edson Yuzur Yasojima.
To evaluate the effects of splenic ischemic preconditioning (sIPC) on oxidative stress induced by hepatic ischemia-reperfusion in rats.
Fifteen male Wistar rats were equally divided into 3 groups: SHAM, IRI and sIPC. Animals from IRI group were subjected to 45 minutes of partial liver ischemia (70%). In the sIPC group, splenic artery was clamped in 2 cycles of 5 min of ischemia and 5 min of reperfusion (20 min total) prior to hepatic ischemia. SHAM group underwent the same surgical procedures as in the remaining groups, but no liver ischemia or sIPC were induced. After 1h, hepatic and splenic tissue samples were harvested for TBARS, CAT, GPx and GSH-Rd measurement.
sIPC treatment significantly decreased both hepatic and splenic levels of TBARS when compared to IRI group (p<0.01). Furthermore, the hepatic and splenic activities of CAT, GPx and GSH- Rd were significantly higher in sIPC group than in IRI group. sIPC was able to attenuate hepatic and splenic IRI-induced oxidative stress.
Ischemia-reperfusion injury (IRI) refers to an exacerbation of cellular damage following restoration of blood flow and oxygen delivery to hypoxic tissues1. It is a common cause of liver dysfunction after major resection/transplantation2 and contributes to a high morbidity and mortality. Pathogenic mechanisms implicated in early hepatic IRI include Kupffer cell activation, release of proinflammatory cytokines and oxidative stress due to the overproduction of reactive oxygen species (ROS)2,3.
All experiments were approved by the Ethics Committee for the Use of Animals, Universidade do Estado do Pará (protocol number: 20/17) and followed the rules of the Brazilian National Law for Animal Care (Law 11.794/08).
IRI group had significantly higher hepatic (45.29 ± 3.18) and splenic (43.74 ± 2.14) levels of TBARS when compared to SHAM group (liver: 7.95 ± 0.57, P < 0.01; spleen: 9.99 ± 0.91, p<0.01). However, sIPC markedly decreased TBARS in liver (37.75 ± 0.94) and spleen (9.94 ± 0.63) as compared to IRI group (p<0.01) (Fig. 1A). CAT concentration was lower in IRI group (liver: 15.10 ± 3.44; spleen: 2.36 ± 0.23) than the SHAM group (liver: 17.53 ± 4.47; spleen: 4.20 ± 0.28), but without statistical difference. Rats from sIPC group showed remarkably higher CAT levels (liver: 84.65 ± 20.77; spleen: 13.05 ± 2.03) than those from IRI group (p<0.01) (Fig. 1B). GPx levels were significantly lower in IRI group (liver: 6.06 ± 1.66; spleen: 17.51 ± 2.86) than the SHAM group (liver: 14.35 ± 1.41, p<0.01; spleen: 23.57 ± 2.82, p<0.05). Notably, compared with the IRI group, sIPC increased GPx levels (liver: 8.81 ± 0.33, p<0.05; spleen: 32.65 ± 4.17, p<0.01) (Fig. 1C). Lastly, IRI mildly reduced GSH-Rd levels (liver: 11.20 ± 3.84; spleen: 12.44 ± 3.95) when compared to SHAM group (liver: 13.85 ± 6.65; spleen: 11.26 ± 2.21), although there was no statistical distinction. In contrast, GSH-Rd levels were significantly higher in sIPC group (liver: 20.51 ± 2.33; spleen: 18.29 ± 1.79) than in the IRI group (p<0.05) (Fig. 1D). To our knowledge, this is the first study to investigate the beneficial effects of sIPC in an experimental model of liver IRI. Our experiment was inspired by the previous report by Shen et al.11, which successfully demonstrated an anti-inflammatory activity of sIPC against renal IRI in rats. In their study, sIPC was achieved through intermittent clamping of the splenic pedicle and 3 cycles of 5 minutes of ischemia and 5 minutes of reperfusion were used. In our sIPC protocol, for the purpose of minimizing surgical trauma on the splenic vasculature, we only performed 2 cycles of 5 minutes of ischemia and 5 minutes of reperfusion. sIPC attenuated hepatic and splenic IRI-induced oxidative stress by enhancing the activity of endogenous antioxidant enzymes, such as CAT, GPx and GSH-Rd. Further studies are needed to confirm these results and elucidate the mechanisms by which sIPC establishes tissue protection. Source: http://doi.org/10.1590/s0102-865020190070000007