Role of Brain-derived Neurotrophic Factor in Cigarette Smoke-exposed Rats

Abstract

Introduction: Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of growth factors, is synthesised in the endoplasmic reticulum. Chronic obstructive pulmonary disease (COPD) is characterised by persistent respiratory symptoms and airflow limitation, in which cigarette smoking is a major risk factor. One previous report demonstrated that lung function of stable COPD patients is associated with the serum levels of BDNF. Cigarette smoke (CS)–induced oxidative stress was also found to increase the expression of BDNF in airway smooth muscle cells. Therefore, this study aimed to investigate the relationship between duration of CS exposure and serum levels of BDNF in CS-exposed passive smoking rat model. Methods: Male Sprague-Dawley (SD) rats, aged 1.5 months, were subjected to 7-day and 56-day CS exposure (SCIREQ inExpose System) to simulate acute and subchronic conditions in COPD. During the subchronic exposure, dosage of Dendrobium officinale polysaccharides (50 mg/kg and 200 mg/kg) was administered daily by oral gavage after CS exposure for 28 days to determine its therapeutic effect in this model. In addition, rat serum from SD rats aged 4 months, 8 months and 15 months were also sacrificed to determine the effects of age on baseline serum levels of BDNF. Results: Duration of CS exposure was found to be positively correlated with serum levels of BDNF. Dendrobium officinale polysaccharides showed its dose-dependent effects on reducing CS-induced serum BDNF levels. The baseline serum levels were also found to increase with age. Conclusion: These findings suggest that BDNF may be used as a biomarker in smokers and Dendrobium officinale polysaccharides may be used as a novel therapy in the treatment of CS-mediated COPD. Acknowledgement: AKC Chan was awarded the HKU Summer Research Fellowship 2018-2019.