BDNF ELISA Kits

BDNF is a molecule that plays an important role in the development and maintenance of nerve function. In recent years, its involvement in various diseases has been reported, leading to growing expectations for its use as a biomarker. proBDNF, the precursor of BDNF, is processed to yield mature BDNF (mBDNF). Since proBDNF and mBDNF show completely different effects, there is a need for a method that can accurately measure mBDNF.

About BDNF

BDNF is a secretory protein, which was isolated from porcine brains by Barde et al. in 1982 as one of neurotrophic factors highly expressed in the brain. BDNF is the second neurotrophic factor identified in the neurotrophin family and is widely distributed in the brain during the development to maturation stage of the nerve system. Its representative known effects include promotion of survival of nerve cells and formation of synapses through a high-affinity receptor, Tropomyosin related kinase B (TrkB).^1,2) As explained above, BDNF is an important factor contributing to the formation and maintenance of nerve function, attracting a lot of attention in neuroscience.

Expectation for biomarkers

It has been suggested that BDNF is deeply involved in diseases caused in the brain, such as psychiatric diseases.³⁾ In depression in particular, its use as a biomarker has been expected since the first report by Karege et al. that the serum BDNF level in patients with depression is lower than that in healthy individuals.⁴⁾ The BDNF level is decreased especially in patients with depression not on antidepressants, suggesting the potential of quantitative analysis of BDNF as an indicator of depression treatment. Some recent meta-analyses have also suggested decreased serum BDNF in patients with bipolar disorder or schizophrenia in addition to depression.⁵⁾ Overall, BDNF is likely to be a key factor for various psychiatric diseases, although its characteristic changes in particular psychiatric diseases are currently unknown.

Mature BDNF and proBDNF

BDNF is expressed as precursor BDNF (proBDNF), transported to the site of secretion, and processed to yield mature BDNF (mBDNF).⁶⁾ It was previously considered that the precursor, proBDNF, had no physiological function, but it has been recently revealed that it has a completely different physiological function from that of mBDNF. mBDNF induces long-term potentiation (LTP) through TrkB to promote neurogenesis and neurodevelopment. On the other hand, proBDNF induces long-term depression (LTD) through a low-affinity receptor, p75NTR, to promote nerve apoptosis (Figure 1).⁷⁾ This change in the effect due to the difference in processing suggests the presence of a highly complicated control mechanism of BDNF on the nerve system. Therefore, a method to accurately measure mBDNF is necessary to reveal the mechanisms of various psychiatric diseases.

Figure1: Processing and Function of BDNF

Development of Mature BDNF detection technology

It is known that specific and sensitive measurement of mature BDNF is very difficult. To address this challenge, we developed Mature BDNF ELISA Kit Wako (Product Number: 296-83201) and Mature BDNF ELISA Kit Wako, High Sensitive (Product Number: 290-85801). These ELISA kits can specifically detect mBDNF using an antibody recognizing the N-terminal side of mBDNF (Figure 2, Table 1). In addition, using Mature BDNF ELISA Kit Wako, High Sensitive, we succeeded in the measurement of mBDNF in mouse serum/plasma and human saliva. This detection technology for mature BDNF is expected to become a powerful tool in psychiatry.

Figure 2: Principle of Mature BDNF ELISA Kit Wako, High Sensitive

Table 1: Sensitivity and cross-reactivity of BDNF ELISA kits

Mature BDNF ELISA Kit Wako, High Sensitive is a sandwich ELISA that combines anti mBDNF N-terminal end-specific monoclonal antibody and anti BDNF monoclonal antibody. The cross-reactivity with proBDNF is substantially reduced by using end-specific antibodies, and the sensitivity is increased through use of a luminescent substrate.

Kit performance

Calibration curve range	0.116 - 50 pg/mL
Reactivity with human proBDNF	1.30%
Analysis sample	Mouse serum/plasma/brain lysate Rat serum/plasma Human serum/plasma/saliva
Sample volume	13 μL (4-fold dilution)
Measurement duration	Approx. 4 hours
Detection method	Luminescence (A plate reader for luminescence measurement is required)

Dilution linearity test

Reactivity with similar proteins

Proteins	Reactivity （%）	Proteins	Reactivity （%）
Human proBDNF	1.30	Mouse proBDNF	0.328
Human NGF-β	< 0.232	Mouse NGF-β	< 0.232
Human NT-3	< 0.232	Mouse NT-3	< 0.232
Human NT-4	< 0.232	Mouse NT-4	< 0.232

[Result]
Very low reactivity with proBDNF and the neurotrophin family (NGF, NT-3, NT-4) was confirmed.

Measurement in brain lysate in wild-type and BDNF knockout mice

Mature BDNF ELISA Kit Wako is a sandwich ELISA using mBDNF monoclonal antibody and BDNF polyclonal antibody. The kit has low cross-reactivity to proBDNF (approx. 10%) because the monoclonal antibody reacts with N-terminal cutting surface of mBDNF.

Kit performance

Calibration curve range	4.1 - 1,000 pg/mL
Reactivity with human proBDNF	Approx. 10%
Analysis sample	Human serum/plasma
Sample volume	Serum: 10μL (10-fold dilution) Plasma: 5μL (20-fold dilution)
Measurement duration	Approx. 4 hours
Detection method	Chromogenic

Application Data

Measured values of mature BDNF in serum from patients with psychiatric disorders

Healthy Control (n=6)	Major depression (n=6)	Bipolar disorder (n=4)	Schizophrenia (n=4)
18.1±3.41 ng/mL	16.3±4.02 ng/mL	15.1±4.53 ng/mL	16.6±5.17 ng/mL

[Result]
mBDNF could be quantified in the serum from psychiatric patients and healthy control.

▼ Poster

Title	Conference	Year	Language	Data
Development of a novel highly sensitive mBDNF sandwich ELISA	Neuroscience 2022	2022	English	PDF

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   Decreased serum brain-derived neurotrophic factor levels in major depressed patients
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   Whither proBDNF?