Brain-Derived Neurotrophic Factor: Physiology and What Research Reports
Brain-derived neurotrophic factor (BDNF) is a neurotrophin — a protein growth factor that supports the survival, growth and signalling of nerve cells. It is made in the brain, including by astrocytes, and also in tissues outside the nervous system such as megakaryocytes and platelets, salivary glands and periodontal tissue. Studies most often measure it in serum or plasma, or map its expression in tissue. Published work has examined BDNF in exercise and cognition, diabetes, retinal disease, alcohol use disorder, dementia-related agitation and brain tumours.
What Brain-Derived Neurotrophic Factor Is
Brain-derived neurotrophic factor, almost always shortened to BDNF, is a member of the neurotrophin family of secreted proteins. Neurotrophins act as growth and maintenance signals for neurons: they bind receptors on nerve cells and influence survival, branching, synapse formation and the strength of synaptic signalling. BDNF is not a short research peptide of the kind found in peptide catalogues — it is a full protein, produced by the body, with a precursor form (proBDNF) that is processed into mature BDNF. Because it is endogenous and widely studied, BDNF appears constantly as an outcome measure in research on brain health, metabolism and neuroactive compounds, which is why readers of peptide and neuroscience literature meet the term so often.
Where BDNF Is Produced
Inside the nervous system
Neurons themselves synthesise and release BDNF in an activity-dependent way, but they are not the only source. A 2023 review in Neuroscience Research examined astrocytes — the most abundant glial cells in the brain — as producers and handlers of BDNF, discussing how astrocytic BDNF contributes to neuronal support and plasticity (PMID 36780947). That review is a useful reminder that BDNF signalling in the brain is a network property involving several cell types, not a single neuronal product.
Outside the nervous system
BDNF is also found well beyond the brain. A 2016 study in The Journal of Biological Chemistry investigated BDNF in megakaryocytes, the bone-marrow cells that give rise to platelets, and researchers described megakaryocytes as a source of the BDNF stored in platelets (PMID 27006395). This matters for interpretation: much of the BDNF measured in blood is platelet-associated rather than a direct read-out of brain tissue.
Peripheral tissues can also change their BDNF expression in response to physiological stress. A 2020 study in the Journal of Oral Biosciences examined the submandibular glands of rats and reported that hypertriglyceridemia was associated with induction of BDNF in that salivary tissue (PMID 32931901). A 2021 animal study looked at occlusal trauma and reported a systemic BDNF response spanning the periodontium, the trigeminal nucleus caudalis and the hippocampus (PMID 34446140), illustrating that a local peripheral insult can be accompanied by BDNF changes in central structures.
What BDNF Does in the Body
In broad terms, the literature treats BDNF as a signal that links neural activity to structural and functional adaptation. Functions repeatedly discussed across the cited work include:
- Neuronal support and plasticity — astrocyte-derived and neuron-derived BDNF are discussed as contributors to neuronal maintenance and synaptic plasticity (PMID 36780947).
- A candidate mediator of cognitive change — a 2017 hypothesis paper in Medical Hypotheses proposed BDNF as the mechanism through which acute exercise produces short-term cognitive improvements (PMID 28818262).
- A link between metabolism and the nervous system — a 2020 review in the International Journal of Molecular Sciences examined BDNF in the context of diabetes and metabolic dysfunction (PMID 32012942).
- Presence in peripheral circulation via platelets — megakaryocyte-derived BDNF was described as contributing to the blood pool of the protein (PMID 27006395).
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Try it freeHow BDNF Is Measured and Studied
Three approaches dominate the published work:
- Circulating BDNF. Serum or plasma concentrations are measured by immunoassay. Clinical studies use this route because it is non-invasive — for example, a 2023 study in the International Journal of Geriatric Psychiatry used serum BDNF as the measured outcome when researchers examined lithium in Alzheimer's patients with agitation (PMID 37732619), and a 2021 report in CNS Spectrums assessed BDNF among patients with alcoholism (PMID 32423492).
- Local fluid sampling. In ophthalmology, BDNF has been measured in eye-related samples: a 2021 study in the European Journal of Ophthalmology examined BDNF in non-proliferative diabetic retinopathy with diabetic macular edema (PMID 32686489), and a 2023 study in the same journal compared BDNF across subtypes of exudative age-related macular degeneration (PMID 35505604).
- Tissue expression. Animal and pathology studies map where the protein or its mRNA is expressed. A 2018 report in Oncology Letters examined expression of nerve growth factor and BDNF in astrocytomas (PMID 29391888), and a 2021 study in Andrologia examined BDNF expression in rapid ejaculator rats (PMID 34101873).
Where BDNF has been studied: a quick map
| Context | Sample or tissue | Citation |
|---|---|---|
| Astrocyte biology | Brain (review) | PMID 36780947 |
| Platelet BDNF origin | Megakaryocytes | PMID 27006395 |
| Diabetes and metabolism | Review | PMID 32012942 |
| Dementia-related agitation | Serum | PMID 37732619 |
| Alcohol use disorder | Patients | PMID 32423492 |
| Retinal disease | Eye studies | PMID 32686489, PMID 35505604 |
| Glial tumours | Astrocytoma tissue | PMID 29391888 |
Interpreting BDNF Measurements: What Studies Report
The breadth of the cited literature is itself the main interpretive lesson. BDNF has been measured in blood, mapped in salivary and periodontal tissue (PMID 32931901, PMID 34446140), and examined in tumour tissue (PMID 29391888), which means a single number labelled "BDNF" can reflect very different biology depending on the compartment sampled. Because platelets carry a large share of blood BDNF (PMID 27006395), serum and plasma values are not interchangeable, and handling differences between laboratories can matter. It is also worth noting that a hypothesis paper such as the 2017 exercise–cognition proposal (PMID 28818262) sets out a mechanism to be tested rather than a demonstrated causal chain.
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Get the appWhy the Term Appears in Peptide Reading
BDNF is one of the most common biomarkers quoted in discussions of neuroactive and metabolic compounds, because it is measurable in blood and because it sits at the intersection of neural plasticity and systemic metabolism (PMID 32012942). When a study describes a compound "increasing BDNF", the informative questions are which compartment was sampled, whether mature BDNF or proBDNF was measured, and whether any functional change accompanied the biomarker shift — as in the serum-BDNF design used in the lithium and agitation study (PMID 37732619). None of the work cited here establishes that changing a BDNF reading changes an outcome in a healthy person.
This page is for educational purposes only and is not medical advice; consult a licensed physician about any health question, symptom or treatment decision. Nothing here describes a protocol, and BDNF itself is an endogenous protein studied in research settings, not a self-administered product.
References
- Astrocytes and brain-derived neurotrophic factor (BDNF) (Neuroscience Research, 2023)
- Effects of lithium on serum Brain-Derived Neurotrophic Factor in Alzheimer's patients with agitation (International Journal of Geriatric Psychiatry, 2023)
- Brain-derived Neurotrophic Factor in Megakaryocytes (The Journal of Biological Chemistry, 2016)
- Brain-Derived Neurotrophic Factor and Diabetes (International Journal of Molecular Sciences, 2020)
- Hypertriglyceridemia-induced brain-derived neurotrophic factor in rat submandibular glands (Journal of Oral Biosciences, 2020)
- Brain-derived neurotrophic factor among patients with alcoholism (CNS Spectrums, 2021)
- Brain-Derived Neurotrophic Factor Systemic Response in the Periodontium, Trigeminal Nucleus Caudalis, and Hippocampus Induced by Occlusal Trauma (Journal of Biomedical Nanotechnology, 2021)
- Brain-derived neurotrophic factor mediates cognitive improvements following acute exercise (Medical Hypotheses, 2017)
- Brain-derived neurotrophic factor in non-proliferative diabetic retinopathy with diabetic macular edema (European Journal of Ophthalmology, 2021)
- Expression of brain-derived neurotrophic factor in rapid ejaculator rats: A further study (Andrologia, 2021)
- Expression of nerve growth factor and brain-derived neurotrophic factor in astrocytomas (Oncology Letters, 2018)
- Comparison of brain-derived neurotrophic factor among subtypes of exudative age-related macular degeneration (European Journal of Ophthalmology, 2023)
Frequently asked questions
What is brain-derived neurotrophic factor in simple terms?▾
BDNF is a protein growth factor for nerve cells. It supports neuronal survival and synaptic plasticity, and a 2023 review discussed astrocytes as an important source and handler of BDNF in the brain alongside neurons (PMID 36780947). It is produced by the body rather than being a synthetic research peptide, and it is widely used as a measurable biomarker in neuroscience studies.
Is BDNF only made in the brain?▾
No. A 2016 study described megakaryocytes, the precursors of platelets, as a source of the BDNF carried in blood (PMID 27006395). Peripheral tissues also express it: researchers reported BDNF induction in rat submandibular glands under hypertriglyceridemia (PMID 32931901), and a systemic BDNF response across periodontium, trigeminal nucleus caudalis and hippocampus after occlusal trauma (PMID 34446140).
How do researchers measure BDNF?▾
Most commonly by immunoassay of serum or plasma, as in the study that used serum BDNF as the outcome when examining lithium in Alzheimer's patients with agitation (PMID 37732619), and in work assessing BDNF among patients with alcoholism (PMID 32423492). Other studies map tissue expression instead, such as the analysis of nerve growth factor and BDNF in astrocytomas (PMID 29391888).
What does the literature say about exercise and BDNF?▾
A 2017 hypothesis paper in Medical Hypotheses proposed that BDNF mediates the cognitive improvements observed after acute exercise (PMID 28818262). Because that paper set out a proposed mechanism rather than a completed trial, it frames a testable idea. It does not establish that any specific intervention changes cognition through BDNF in a given individual.
Why is BDNF discussed in diabetes and eye disease research?▾
A 2020 review examined BDNF in relation to diabetes and metabolic dysfunction (PMID 32012942), placing it at the interface of metabolism and the nervous system. In ophthalmology, one study examined BDNF in non-proliferative diabetic retinopathy with diabetic macular edema (PMID 32686489), and another compared BDNF across subtypes of exudative age-related macular degeneration (PMID 35505604).
Does a higher BDNF blood level mean better brain function?▾
The cited literature does not support that simple reading. Much circulating BDNF is platelet-associated (PMID 27006395), so serum and plasma values reflect different things, and BDNF has also been measured in tumour tissue (PMID 29391888) and peripheral organs (PMID 32931901). A biomarker shift is not the same as a functional outcome, and interpretation depends on the compartment sampled.
Is BDNF something a person can obtain or use?▾
BDNF is an endogenous protein studied in laboratory and clinical research settings, not a consumer product, and this page does not discuss administration. Published studies used it as a measured variable — for example serum BDNF as an outcome in Alzheimer's-related agitation research (PMID 37732619). This page is educational only and is not medical advice; a licensed physician should be consulted about health questions.
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References
This page summarises published research for education — it is not medical advice, and nothing here is a recommendation to use, purchase, or dose any substance. Study parameters described are what researchers reported, not instructions. Consult a qualified clinician before any health decision.