Virtually unique among somatic tissues, the brain and spinal cord lack a lymphatic system. Despite the high metabolic activity and fragility of neural tissue, there exists no effective understanding of the means by which interstitial fluid and waste products are removed from the CNS. Our preliminary analysis, based on in vivo two- photon imaging, shows that low molecular weight tracers delivered to the CSF circulate surprisingly rapidly through the mouse brain, and do so along a surprising anatomical route. This consists of a para-arterial inflow path, a trans-glial intra-parenchymal path of interstitial flow, and a para-venous outflow path. Within the intra- parenchymal pathway, astrocytes support convective fluid currents through the brain interstitial space, as deletion of the astrocytic water channel AQP4 sharply reduces overall tracer flow along these routes. Given the continuous movement of fluid supported by this pathway, and its critical dependence upon astrocytic water transport, we propose that this system - which we designate here the 'glymphatic system'- subserves a function homologous to the peripheral lymphatic system, and is essential for the clearance of metabolic waste products from the CNS.
Aim 1 will use 2-photon in vivo microscopy to assess the spatial dynamics and temporal kinetics of fluorophore-tagged tracer clearance. By systematically comparing the effect of modifications of molecular sizes or surface charge upon tracer clearance, we will define the basic transport properties of the glymphatic system.
Aim 2 will extend the preliminary observation that aged mice exhibit a striking decline in glymphatic system function, and evaluate the role of age-related suppression of arterial wall pulsation and resulting reduced convective inflow along the para-arterial path and global glymphatic fucntion.
Aim 3 proposes that induced knock-out of either astrocytic AQP4 water channels or gap junctions (Cx43/Cx30) will slow parenchymal convective fluid flow and globally suppress tracer clearance.
Aim 4 tests the proposition that suppression of trans-astroglial fluid movement resulting from AQP4 or Cx43/Cx30 deletion will slow clearance of exogenous A? and thereby potentiate age-related amyloid plaque formation. We predict that slowing astrocytic parenchymal fluid flow will accelerate paravascular amyloid deposition, which in a feed- forward manner will further reduce the efficiency of clearance of waste products by the glymphatic system. To our knowledge, these studies represent the first attempt to systematically define the mechanisms involved in the clearance of metabolic waste products from the brain on a whole-organ level. Two-photon imaging of through chronic cranial windows will allow imaging of tracer clearance in real time, whereas transgenic mice with inducible deletion of key astroglial membrane proteins will establish the functional role of astrocytes in glymphatic transport. Combined, these studies will provide fundamental insight into the mechanisms contributing to age-related accumulation of neurotoxic metabolic waste products and define novel, and likely highly important, functional properties of astrocytes.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
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Cellular and Molecular Biology of Glia Study Section (CMBG)
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Corriveau, Roderick A
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University of Rochester
Schools of Dentistry
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Smith, Nathan A; Kress, Benjamin T; Lu, Yuan et al. (2018) Fluorescent Ca2+ indicators directly inhibit the Na,K-ATPase and disrupt cellular functions. Sci Signal 11:
Plog, Benjamin A; Nedergaard, Maiken (2018) The Glymphatic System in Central Nervous System Health and Disease: Past, Present, and Future. Annu Rev Pathol 13:379-394
von Holstein-Rathlou, Stephanie; Petersen, Nicolas Caesar; Nedergaard, Maiken (2018) Voluntary running enhances glymphatic influx in awake behaving, young mice. Neurosci Lett 662:253-258
Lee, Hedok; Mortensen, Kristian; Sanggaard, Simon et al. (2018) Quantitative Gd-DOTA uptake from cerebrospinal fluid into rat brain using 3D VFA-SPGR at 9.4T. Magn Reson Med 79:1568-1578
Kjaerby, Celia; Rasmussen, Rune; Andersen, Mie et al. (2017) Does Global Astrocytic Calcium Signaling Participate in Awake Brain State Transitions and Neuronal Circuit Function? Neurochem Res 42:1810-1822
Benveniste, Helene; Lee, Hedok; Ding, Fengfei et al. (2017) Anesthesia with Dexmedetomidine and Low-dose Isoflurane Increases Solute Transport via the Glymphatic Pathway in Rat Brain When Compared with High-dose Isoflurane. Anesthesiology 127:976-988
Ratner, Vadim; Gao, Yi; Lee, Hedok et al. (2017) Cerebrospinal and interstitial fluid transport via the glymphatic pathway modeled by optimal mass transport. Neuroimage 152:530-537
DiNuzzo, Mauro; Nedergaard, Maiken (2017) Brain energetics during the sleep-wake cycle. Curr Opin Neurobiol 47:65-72
Wang, Minghuan; Ding, Fengfei; Deng, SaiYue et al. (2017) Focal Solute Trapping and Global Glymphatic Pathway Impairment in a Murine Model of Multiple Microinfarcts. J Neurosci 37:2870-2877
Louveau, Antoine; Plog, Benjamin A; Antila, Salli et al. (2017) Understanding the functions and relationships of the glymphatic system and meningeal lymphatics. J Clin Invest 127:3210-3219

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