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Summary: <\/strong>A new study has upended the long-held neurological assumption that sodium concentrations are uniform across the brain\u2019s star-shaped glial cells, or astrocytes. Researchers developed a novel imaging technique to visualize sodium content in real-time within astrocytes and their ultra-fine microscopic processes for the first time.<\/p>\n The data reveals that instead of a static baseline, highly specialized sodium micro-domains fluctuate dynamically across individual cells and sub-domains to match the local excitability needs of neighboring neural networks.<\/p>\n Key Facts<\/strong><\/p>\n Source: <\/strong>HHU<\/p>\n 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 \u201castrocytes\u201d.<\/strong><\/p>\n 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.<\/p>\n 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 \u2013 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.<\/p>\n 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 f\u00fcr Bildung und Forschung<\/em>\u00a0\u2013 BMBF),\u00a0which can make the sodium content in the astrocytes and their fine processes directly visible in brain tissue for the first time.<\/p>\n Together with researchers from Friedrich-Alexander-Universit\u00e4t Erlangen-Nuremberg, the University of Bonn, the University Hospital Bonn, and the University of South Florida in Tampa (USA), the neurobiologists in D\u00fcsseldorf 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.<\/p>\n They actually established that this is not the case. Rather, they discovered differences \u2013 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.<\/p>\n 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 D\u00fcsseldorf were validated in animal models by the colleagues in Bonn.<\/p>\n Dr Jan Meyer, lead author of the study: \u201cWe 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.\u201d<\/p>\n The head of the study, Professor Christine Rose, highlights further aspects: \u201cThese 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.\u201d<\/p>\n A<\/strong>: To serve as a responsive neighbor. Astrocytes are responsible for managing neurotransmitters and keeping nerve cell signals under control. Because different synapses in a neural network are firing at different rates, the astrocyte creates specialized, isolated sodium sub-domains within its fine branches to instantly match the custom, hyper-local needs of nearby neurons.<\/p>\n<\/div>\n A<\/strong>: It was a complete multi-scale validation. The primary discovery was made using a new imaging technique on isolated brain tissue in D\u00fcsseldorf. To confirm it wasn\u2019t a laboratory anomaly, biophysicists in South Florida built computer models that perfectly mirrored the patterns in simulations, while neurobiologists in Bonn verified the exact same localized variations inside living animal models.<\/p>\n<\/div>\n A<\/strong>: It offers a completely fresh direction for targeted drug research. Conditions like epilepsy and stroke are fundamentally driven by massive, toxic disruptions in brain ion levels and neurotransmitter regulation. Knowing that astrocytes rely on specific transport molecules to manage these hyper-local sodium sub-domains allows scientists to develop medications that protect these cellular pumps from collapsing during an emergency.<\/p>\n<\/div>\n<\/div>\n Author:\u00a0<\/strong>Arne Claussen<\/a>\n
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About this neuroscience research news<\/h2>\n
Source:\u00a0<\/strong>HHU<\/a>
Contact:\u00a0<\/strong>Arne Claussen \u2013 HHU
Image:\u00a0<\/strong>The image is credited to HHU\/Institute of Neurobiology \u2013 Jan Meyer<\/p>\n