Neural Noise

tDCS mechanisms via neurovascular unit: a review

2 min read

  • A review addresses the mechanisms of transcranial direct current stimulation (tDCS) via the neurovascular unit.1
  • Understanding the neurovascular basis of tDCS effects supports mechanistic models and clinical translation.1 1

Weekly enrichment (2026-07-20)

  • The likely source is a 2025 Frontiers in Neuroscience narrative review that synthesizes acute and enduring tDCS effects across the entire neurovascular unit: neurons, astrocytes, oligodendrocytes, microglia, the blood–brain barrier, plus metabolic and immune responses, arguing against a purely neuron-centric account.2
  • The review draws on transcriptomic, proteomic, and metabolomic studies showing tDCS induces coordinated molecular changes, including modulation of genes for inflammation, neurogenesis, calcium signalling, mitochondrial metabolism, and synaptic-plasticity proteins, and flags astrocytes and oligodendrocytes as understudied.2
  • A companion mechanistic framework (Brain Stimulation, 2021) distinguishes primary versus secondary vascular effects of transcranial electrical stimulation, tracing them to four cellular elements: perivascular nerves of dural/pial arteries, the endothelial lining of all vessels including BBB microvasculature (both giving an immediate, primary vasodilatory response), plus astrocytes and neurons (secondary neurovascular coupling).3
  • In vivo rat work shows tDCS transiently and reversibly increases BBB permeability, with a smaller fold-increase for a small solute (sodium fluorescein, MW 376) than for a large solute (Dextran-70k); permeability returns to control roughly 20 min post-stimulation.4
  • Modeling attributes that permeability rise to transient degradation of the endothelial surface glycocalyx and extracellular matrix, disruption of endothelial tight junctions, and widening of gaps between endothelial cells and astrocyte foot processes, mediated by astrocytic Ca2+ surges and nitric-oxide-synthase (NOS)-dependent NO release.4
  • A current-flow modeling estimate cited in this literature proposes that current funneling into capillaries produces a greater-than-400-fold amplification of the electric field across the BBB, making endothelial cells and perivascular astrocytes plausible direct targets.5
  • In isolated cells, direct current stimulation altered gene expression in both endothelial cells and astrocytes (e.g., BDNF, NOS3, VEGFR1, and the immediate-early gene FOS, which rose as much as 24-fold), linking vascular-unit modulation to downstream neuroplasticity.5
  • Complementary in vivo imaging shows direct current stimulation raises cortical microvascular blood flow and permeability even in the absence of neuronal activity, consistent with a direct action on smooth muscle cells and capillary pericytes alongside classic activity-dependent neurovascular coupling.6

Footnotes

  1. https://news.google.com/rss/articles/CBMiX0FVX3lxTFBUVHFZYURIZk1icUxYb2tHb29YYVR5T0VGSVdLV1RiWHdWbFJOSUhubEJPeFp2MHY1cVo5U2FlcnhaZDZWZ0lXbzhBSkRXNlBpWHEzMUlBVjRRZVRESmtn?oc=5 ↩ ↩2 ↩3

  2. https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2025.1667100/full ↩ ↩2

  3. https://www.sciencedirect.com/science/article/pii/S1935861X21000851 ↩

  4. https://pmc.ncbi.nlm.nih.gov/articles/PMC7096245/ ↩ ↩2

  5. https://www.nature.com/articles/s41598-022-22394-8 ↩ ↩2

  6. https://doi.org/10.1111/ene.15616 ↩

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