Associations between serum and plasma brain-derived neurotrophic factor and influence of storage time and centrifugation strategy

Anne Kær Gejl,Christian Enevold,Claus Henrik Nielsen,Lars Bo Andersen,Anna Bugge,Marianne Skovsager Andersen

doi:10.1038/s41598-019-45976-5

Abstract

The aims of the study were to clarify the impact of storage time and centrifugation strategy on brain-derived neurotrophic factor (BDNF) levels in human serum and plasma samples. In addition, we analyzed associations between BDNF levels, cardiorespiratory fitness and waist circumference. Seventeen healthy males (25.2 (4.1) years) were included in the study. Blood samples were drawn after an overnight fast and treated to different protocols, varying in time before centrifugation and centrifugation strategy. BDNF was analyzed in serum, normal plasma (NP) and platelet-poor plasma (PPP). Also, waist circumference and cardiorespiratory fitness were measured. A large increase was observed in serum BDNF levels during the first hour of clotting. BDNF in NP correlated with PPP, whereas no correlations were found between BDNF in serum and plasma. Though not statistical significant, correlations between fitness and BDNF in serum changed from positive at 30 min. to negative when clotting time was ≥60 min. In conclusion, BDNF levels in serum were affected by clotting time, whereas BDNF levels in plasma were influenced by centrifugation strategy. Importantly, BDNF in serum and plasma appears to reflect two different pools of BDNF. The biological relevance of the velocity of BDNF release during clotting and its dependence upon fitness must be investigated further.

Highlights

Brain-derived neurotrophic factor (BDNF) is a growth factor protein and member of the neurotrophin family, which includes, neurotrophin 3 and neurotrophin 4/51
Www.nature.com/scientificreports and platelet-poor plasma. (C) An increase in brain-derived neurotrophic factor (BDNF) levels measured in serum was observed between 30 and 60 min. (A) No systematic changes were observed in plasma BDNF over time (B & C)
Significant differences were observed between BDNF levels measured in serum, platelet-poor plasma (PPP) and normal plasma (NP), with BDNF in serum > NP > PPP

Summary

Introduction

Brain-derived neurotrophic factor (BDNF) is a growth factor protein and member of the neurotrophin family, which includes, neurotrophin 3 and neurotrophin 4/51. It is uncertain how precisely BDNF levels measured in venous blood samples reflects circulating BDNF levels in vivo, and how various methodological approaches affect the result of the analysis It is well-established that much higher concentrations of BDNF are observed in serum than in plasma[12,13]. The primary objectives of the present study were 1) to determine how time between collection and centrifugation of blood samples as well as centrifugation strategy impact measured levels of peripheral BDNF (i.e. in serum and plasma), and 2) to determine any association between BDNF measured in serum, normal plasma (NP) and platelet-poor plasma (PPP). BDNF measured in plasma have been found to be positively associated with cardiorespiratory fitness[24,25] and negatively with cardiovascular risk factors[25] Such findings suggest that the application of various methodological approaches may influence the direction of these associations. Secondary objectives were to explore if BDNF levels assessed under different circumstances were associated with cardiorespiratory fitness and/or waist circumference, and the directions of these associations

Objectives

Results

Conclusion