The Study
NH4+ triggers the release of astrocytic lactate via mitochondrial pyruvate shunting
This study watched how brain cells in a dish and in mice reacted to a chemical called NH4+, and saw that they made more lactate. But we don’t know if this is a real cause-and-effect relationship or just something that happened to occur. It’s like seeing a dog bark every time the doorbell rings — you can’t say the doorbell caused the barking without more proof.
Analysis score
Maximum 58 for a case-control study.
Where the score came from
When neurons fire, they release a waste gas called NH₄⁺. This gas tells nearby brain support cells (astrocytes) to make more lactate — a fuel — without using more sugar.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 512 / 100
Quality score
Researchers compare people who have a condition (cases) with similar people who do not (controls), looking back in time for differences in exposure. Useful but more prone to bias.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means brain cells can quickly supply energy to active neurons during thinking or learning, using a signal tied directly to neural activity.
- 2NH₄⁺ at 0.05–0.2 mM caused astrocytes to produce and release more lactate within seconds, without changing glucose use.
- 3Pyruvate built up in cells and mitochondrial uptake dropped by 93%.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Proceedings of the National Academy of Sciences
Year
2015
Authors
R. Lerchundi, I. Fernández-Moncada, Y. Contreras-Baeza, T. Sotelo-Hitschfeld, P. Mächler, M. Wyss, J. Stobart, F. Baeza-Lehnert, K. Alegría, B. Weber, L. F. Barros
Related Content
Claims (6)
Lactate is moved between cells and used in the mitochondria of heart and brain cells to produce energy.
When ammonium ions lower the pH inside mitochondria of astrocytes, the transport of pyruvate into mitochondria decreases, causing more pyruvate to be converted into lactate.
At normal levels found in the brain, ammonium ions cause astrocytes to produce and release more lactate quickly and reversibly, without changing how much glucose they take up.
At normal levels in the brain, ammonium ions block pyruvate from entering mitochondria in astrocytes, causing pyruvate to build up in the cytoplasm and be converted to lactate, which is then released, without increasing glucose use.
Ammonium ions at normal levels in the brain do not increase glucose use by astrocytes, while glutamate and potassium ions do.
During brain signaling, ammonium ion is generated alongside glutamate and quickly released into the space between neurons, where it may act as a metabolic signal alongside neurotransmitters.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.