Effect of therapeutic hypothermia on lipopolysacharide induced bronchopulmonary dysplasia model

Bronchopulmonary dysplasia (BPD) is one of the most significant morbidity in preterm infants and a developmental disorder characterized by lung tissue inflammation, fibrosis. Today, there is not a unique method for successfully prevent the development of BPD. The use of therapeutic hypothermia is known for many years that show its effects by regulation of energy metabolism, inflammation, apoptosis and oxidant system. The use of therapeutic hypothermia is the only form of treatment in the neonatal hypoxic ischemic encephalopathy. Our study aims to evaluate the efficacy of therapeutic hypothermia in prevention of BPD.Twentyfour wistar rat pups born from four mothers were used for this purpose. The groups were: (1) control, (2) antenatal Lipopolysacharide (LPS) induced BPD (3) antenatal LPS induced BPD + hypothermia and (4) hypothermia. İntraperitoneal LPS (400 µg/kg) was injected to maternal rat at 19th and 20th gestational days to establish BPD model. In hypothermia groups hypothermia started at postnatal 24th hour administered during 24 hours keeping rectal body temperature as 34 0C. Body temperatures of the rat pups measured per hour. At postnatal 7th day rats were sacrificed under ether anestesia and their lungs were removed by thoracothomy. Lung samples were evaluated for immunohistochemical tests and proinflamatuar gene expression levels .In antenatal LPS applied group comparing with control group, alveolar surface area decreased, fibrotic changes and smooth muscle content was increased and gene expression of inflammatory cytokines were higher. Hypothermia therapy increased alveolar surface area and decreased fibrosis and smooth muscle content. Furthermore, hypothermia therapy reduced gene expression of pro-inflammatory cytokine levels (IL6, İL1 ?, IL1 ß, TNF-? ).Results of this study indicated that hypothermia therapy is effective in LPS induced BPD model. If these results are supported by further studies, hypothermia will be a new therapy option for preventing BPD