Brain derived neurotrophic factor levels in patients undergoing therapeutic hypothermia

AIM: Neonatal hypoxic ischemic encephalopathy (HIE) is a brain injury caused by perinatal asphyxia. Although therapeutic hypothermia is one of the standard treatment protocols, neonatal HIE is still one of the most important causes of neonatal death and long-term poor neurological prognosis. The aim of this study was to investigate serum BDNF levels in neonatal hypoxic ischemic encephalopathy and to compare serum BDNF levels of first-stage HIE patients and second and third-stage HIE patients undergoing therapeutic hypothermia. Our aim was to evaluate the relationship between serum BDNF levels and the clinical and neurological scoring system, Thompson scoring, in which subjects were evaluated daily. MATERIALS AND METHODS: Thirty neonatal HIE patients with a gestational age of 36 weeks or more followed at Adnan Menderes University Faculty of Medicine Department of Child Health and Diseases, Newborn Unit between 02.08.2018 and 02.08.2019 were included in the study. The control group included the same number of healthy term newborns who were followed at the Obstetrics and Gynecology Department or who presented to the neonatal outpatient clinic during the first five days of life. Blood samples for serum BDNF levels were obtained from the case and control groups within the first six hours of life, on the 3rd and 5th days. BDNF levels in serum samples were studied by ELISA method. Statistical analyzes were performed with SPSS package program and Student t-test, Mann Whitney U test, Pearson test, Spearman test, Friedman test were used. Statistical significance level was accepted as p˂0.05. RESULTS: The mean BDNF levels measured in the first six hours of life were 545.73 ± 108.5 pg / mL in the case group and 633.77 ± 53.61 pg / mL in the control group, 80 and this value was found to be significantly lower in the case group than in the control group (p<0.001). No statistically significant difference was found between the BDNF values of the case group and control group on the 3rd and 5th day (p=0.485, p=0.657). There was no statistically significant difference between the moderate-severe HIE group and the mild HIE group in terms of BDNF values measured in the first six hours of life and on the 3rd and 5th days (p=0.174, p=0.069, p=0.722). BDNF levels on day 3 and day 5 were significantly higher in the case group compared to BDNF levels in the first six hours of life (p = 0.015, p = 0.004). In the control group, BDNF levels on the fifth day were significantly lower than the BDNF levels measured in the first six hours of life (p = 0.002). In the case group, a significant positive correlation was found between the Thompson scores measured on the first five days of life and BDNF values measured on the third day (p <0.05). CONCLUSION: Serum BNDF levels are lower in neonatal HIE patients who underwent passive hypothermia in the first six hours of life compared to healthy controls. There was no significant difference between BDNF levels on the third and fifth days of neonatal HIE cases treated with therapeutic hypothermia and healthy controls. Therapeutic hypothermia is thought to modulate this expected increase in neonatal HIE patients. In healthy controls, BDNF levels on the fifth day were lower than BDNF levels measured in the first six hours of life, whereas BDNF levels on the third and fifth days were higher in the neonatal HIE patients undergoing therapeutic hypothermia than in the first six hours of life. There is a positive correlation between BDNF levels on the third day and Thompson scores in the first five days in patients with neonatal HIE who underwent therapeutic hypothermia. BDNF levels taken on the third day will be higher in clinically more severe cases. This finding demonstrates the importance of BDNF as a biomarker that can help predict short-term prognosis in neonatal HIE patients. Key words: Neonatal hypoxic ischemic encephalopathy, therapeutic hypothermia, BDNF, Thompson score, biomarker