The element sodium plays a key role in nervous system function. An international research team headed by the Institute of Neurobiology at Heinrich Heine University Düsseldorf (HHU) has now conducted a closer examination of the sodium concentration in astrocytes – special cells in the brain. To achieve this, the researchers developed a method, via which they can make the sodium content of individual cells in tissue directly visible, as they now describe in the scientific journal Nature Communications.
The brain does not solely comprise nerve cells (neurons); roughly half of the organ is made up of so-called glial cells, which play an important role in brain development and are crucial for communication between neurons and the function of neural networks. Glial cells also include so-called star cells or “astrocytes”.
The element sodium, or rather positively charged sodium ions, are the most important electrolytes in the human body. These ions are crucial for many bodily functions. The main source thereof is table salt (NaCl), which is obtained from food.
Sodium ions are also involved in many processes in the brain, meaning that their concentration must be strictly regulated. In astrocytes, a low intracellular sodium concentration is important among other things for the regulation of neurotransmitters at the synapses – the junctions between nerve cells. It is also important for regulating the levels of other electrolytes. This enables astrocytes to ensure the functionality of nerve cells and regulate their excitability.
At the Institute of Neurobiology at HHU, the team led by Professor Dr Christine Rose has now developed a new technique as part of a study (the SynGluCross project) funded by the Federal Ministry of Education and Research ( Bundesministerium für Bildung und Forschung – BMBF), which can make the sodium content in the astrocytes and their fine processes directly visible in brain tissue for the first time. Together with researchers from Friedrich-Alexander-Universität Erlangen-Nuremberg, the University of Bonn, the University Hospital Bonn, and the University of South Florida in Tampa (USA), the neurobiologists in Düsseldorf set out to test the existing assumption that there is a similarly low concentration of sodium in all astrocytes and in all their sub-units to enable the astrocytes to perform their vital tasks reliably.
They actually established that this is not the case. Rather, they discovered differences – both between individual astrocytes and within various sub-units of these cells. Together with their colleagues from Erlangen-Nuremberg, they also demonstrated that certain transport molecules, which can be found in the cell membrane of various astrocytes in differing numbers and configurations, are responsible for these differences.
The cooperation partners from the USA implemented these findings in biophysical computer models and were able to replicate the experimental results in simulations. The findings obtained in isolated brain tissue in Düsseldorf were validated in animal models by the colleagues in Bonn.
Dr Jan Meyer, lead author of the study: “We were also able to show that specialised functional sub-domains exist in astrocytes due to the different sodium concentrations. In each case, they react to the local needs of their neighbouring neural network.”
The head of the study, Professor Christine Rose, highlights further aspects: “These newly discovered properties of astrocytes may also play a role in various brain disorders where ion levels and neurotransmitter regulation are disrupted, such as epilepsy, or after a stroke. Our findings thus offer starting points for further research.”
Jan Meyer, Viola Bornemann, Alok Bhattarai, Sara Eitelmann, Petr Unichenko, Simone Durry, Karl W. Kafitz, Nicholas Chalmers, Jianfeng Fan, Ruth Beckervordersandforth, Christian Henneberger, Ghanim Ullah and Christine R. Rose; Cellular and subcellular heterogeneity of astrocytic Na⁺ homeostasis tuning astrocytes into functionally distinct subgroups in the mouse brain; Nature Communications 17:4515 (2026)
DOI: 10.1038/s41467-026-73435-z
Nature Communications
Cellular and subcellular heterogeneity of astrocytic Na⁺ homeostasis tuning astrocytes into functionally distinct subgroups in the mouse brain
20-May-2026