Establishment of an MODS model in aged rats

Objective To establish a rat model of multiple organ dysfunction syndrome (MODS) for the further studies of the pathogenesis of MODS. Methods A total of 210 aged rats (24 month old) were randomly divided into three groups ( n =70): oleic acid plus lipopolysaccharide group (O+LPS), oleic acid group (O), and lipopolysaccharide group (LPS). Rats in O+LPS group received intravenous injection of 0.175 ml/kg (BW) oleic acid at first, and then 2.5 ml/kg (BW) LPS 8 h later. Rats in O group and LPS group, however, received intravenous injection of oleic acid and LPS, respectively. After injection, all rats received 1.5 L/min oxygen therapy for 4 h (except the group at 1 h after injection). The functional changes of the heart, liver, kidney, and small intestine before intravenous injection and at 1, 6, 12, 24, 72, and 120 h after injection were observed. In addition, the incidences of systemic inflammatory response syndrome (SIRS) and MODS, and the mortality of rats in all groups were observed. Results During the period of 1-24 h after injection, the PaO 2 in O+LPS group was less than 9.3 kPa, but the levels of alanine aminotransferase, total bilirubin, urea nitrogen, creatinine, aspartate aminotransferase, creatine phosphokinase, and diamine oxidase were significantly higher than those of the auto control before injection ( P 0.05,0.01). The mortality of rats in O+LPS group (33.3%) was higher than that in LPS group (23.3%) and in O group (13.3%) ( P 0.01), and the incidence of MODS rats in O+LPS group (70%) was higher than that in rats in LPS group (17.4%) and in O group (15.4%) ( P 0.01). Conclusion The model established by injectionof oleic acid and lipopolysaccharide subsequently, which can successfully imitate the development of MODS after acute lung injury and secondary infection, is a suitable model for the studies of the primordial role of lung in the pathogenesis of the MODS.