OBJECTIVETo investigate the effects of co-exposure to hyperthermia and lipopolysaccharides (LPS) on tumor necrosis factor-alpha (TNF-alpha) expression in the lungs and small intestines of rats.

METHODSMale pathogen-free Wistar rats were randomly assigned into saline-injected normothermic control (C), saline heat exposure (H), LPS normothermic control (L), and LPS plus heat exposure (HL) groups. The rats in H and HL groups were exposed in a chamber at an ambient dry bulb temperature (Tdb) of 35.0-/+0.5 degrees celsius;, and those in C and L groups to 26-/+0.5 degrees celsius;. In L and HL groups, the rats were given an intravenous injection of LPS 10 mg/kg via the tail vein to induce endotoxemia, and those in C and H group received 10 ml/kg injection. The plasma levels of sTNFrI and sTNFrII were detected at different time points using ELISA. The expression of TNF-alpha in the lungs and small intestines was detected by immunohistochemical SABC method, and the damage of the lungs and small intestines evaluated histologically 120 min after the treatment.

RESULTSCo-exposure to hyperthermia and LPS caused significantly enhanced expressions of TNF-alpha and its receptor sTNFrI and sTNFrII in the plasma and tissues and obvious histopathological damage in the lung and small intestines.

CONCLUSIONCo-stress of hyperthermia and LPS-induced toxicity is associated with the expression of TNF-alpha in the lung and small intestines.