Carbon dioxide pneumoperitoneum induces anti-inflammatory response and hepatic oxidative stress in young rats with bacterial peritonitis

Purpose The aim of this study was to investigate the effects of carbon dioxide (CO2) pneumoperitoneum on the intra-abdominal spread of bacteria, the local and systemic cytokine expression, and oxidant/antioxidant status in young rats with bacterial peritonitis. Methods Young Sprague–Dawley rats, aging 20–27 days and weighing around 50 g, were allocated to six groups of six to nine animals in each. Intra-abdominal infection model was developed by intraperitoneal injection with 1 cc of Escherichia coli (E. coli) (108 CFU/mL, ATCC25922 strain) via right lower abdominal wall. Carbon dioxide (CO2) pneumoperitoneum was applied to the rats via umbilical pit insufflation with 20 cc CO2 for 30 min. All survived rats underwent laparotomy and were killed 24 h or 3 days later. Serum levels of CO2 and CRP were measured. Left lower abdomen peritoneum, peritoneal fluid, mesenteric lymph node of terminal ileum, and liver were taken for bacterial culture. Liver and plasma levels of TNF-a, IL-1b, and IL-6 were examined for the level of local and systemic immunologic response. Oxidant/antioxidant status in liver and plasma were assessed by measuring malondialdehyde (MDA), and reduced to oxidized glutathione ratio (GSH/GSSG). Results Carbon dioxide (CO2) pneumoperitoneum does not facilitate E. coli dissemination to other intra-abdominal organs in rats with localized E. coli peritonitis. Peritonitis rats that underwent abdominal CO2 insufflation have insignificantly higher CRP or lower CO2 levels. Plasma and liver TNF-a, IL-1b concentrations were not significantly different among the four groups, but plasma IL-6 was significantly increased in rats with E. coli peritonitis and CO2 pneumoperitoneum that were killed 3 days later as compared with that of rats that were killed 24 h later. In rats with E. coli peritonitis, CO2 pneumoperitoneum was significantly associated with decreased hepatic GSH/GSSG ratio. However, plasma and liver MDA levels were not altered after CO2 pneumoperitoneum. Conclusions Carbon dioxide (CO2) pneumoperitoneum is not associated with E. coli dissemination in the presence of local intra-abdominal infection. CO2 pneumoperitoneum elicited systemic anti-inflammatory response at a specific time period and decreased hepatic antioxidant status in young rats with E. coli peritonitis.