Effects of Gram-negative Bacteria, E.coli and Cold Exposure on Free Radicals Production, Lactate Dehydrogenase and Glutathione Peroxidase Activity in the Lungs of Rats, Rattus norvigicus

The purpose of this study was to explore the effects of LPS-gram negative bacteria and low ambient temperature on free radicals (FR) production, the activities of lactate dehydrogenase (LDH) and glutathione peroxidase (GPx) in the lungs of rats, Rattus norvigisu. Twenty four male rats, matched with age and weigh, were divided randomly into four groups namely control (C), Bacteria (B), cold temperature (T), and bacteria plus cold (BT). The T group was exposed to 10-12° C ambient temperature for 3 days. Animals of the BT was injected LPS bacteria (IP, 500 μg/kg) during the last five hour of cold exposure to 10-12° C for 3 days. In comparison with C group FR increased significantly (p 0.05) in the experimental groups, indicating high rate of reactive oxygen species (ROS) accumulation. The activity of LDH increased significantly (p 0.05) in the T and BT groups, which demonstrated that bacteria and exposure to cold are causes for cellular injury in the lungs. The synergetic effect of both bacteria and cold on LDH was more intense, as compared with the single effect. The activity of GPx increased significantly (p 0.05) in the B and BT, as compared with the C group. The results of the present study is the first worldwide report to demonstrate that both cold exposure and bacteria infection are mediated by elevation in FR generation.