Effect of induced hypothermia on lipopolysaccharide-induced lung injury in neonatal rats

Abstract

Objectives: Recent data suggest that induced hypothermia has some protective effects on experimental lung injury. We aimed to evaluate the protective effect of mild hypothermia in a rat model of lipopolysaccharide (LPS) induced neonatal lung injury.Methods: Wistar rat pups were divided into four groups, specifically: (i) A control group, with no LPS administration and maintained in room air; (ii) A LPS group, with antenatal LPS administrated and maintained in room air; (iii) A LPS + hypothermia group, with antenatal LPS administrated and exposed to hypothermia; (iv) A hypothermia group, with no LPS administration and exposed to hypothermia. Intraperitoneal LPS was injected into maternal rats at the 19th and 20th gestational days to establish a neonatal lung injury model. Mild hypothermia was started at the postnatal 24th hour and continued during 24 h. At the postnatal 7th day, the rats were sacrificed and lung samples were evaluated for immunohistochemical tests and proinflammatory gene expression levels.Results: Hypothermia therapy attenuated the damaging effects of antenatal LPS administration. Furthermore, hypothermia therapy reduced gene expression of pro-inflammatory cytokines (IL-6, IL-1α, IL-1β, TNF-α) and induced the expression of a potent anti-inflammatory cytokine (IL-10).Conclusion: The results of this study indicated that mild hypothermia therapy is effective in an LPS induced neonatal lung injury model. If these results are supported by further studies, hypothermia may also be a new therapy option for preventing bronchopulmonary dysplasia.