Aquaporin 4 correlates with apparent diffusion coefficient and hydrocephalus severity in the rat brain: A combined MRI–histological study

Tourdias, Thomas; Dragonu, Iulius; Fushimi, Yasutaka; Deloire, Mathilde; Boiziau, Claudine; Brochet, Bruno; Moonen, Chrit; Petry, Klaus G.; Dousset, V.

doi:10.1016/j.neuroimage.2009.04.070

Cited by 93 publications

(90 citation statements)

References 26 publications

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“…Increased expression of AQP4 or Aqp4 mRNA has been found in numerous conditions, including bacterial meningitis (141), inflammation secondary to intraparenchymal injection of lipopolysaccharides (LPS) (187) or lysolecithin (190), subarachnoid hemorrhage (198), intracerebral hemorrhage (182), brain tumors (32,135,164), and hydrocephalus (100,144,168,170,189). It is still not known whether changes in surface expression of AQP4 occur under physiological conditions.…”

Section: Regulationmentioning

confidence: 99%

Physiological Roles of Aquaporin-4 in Brain

Nagelhus

Ottersen

2013

Physiological Reviews

579

520

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(AQP4) is one of the most abundant molecules in the brain and is particularly prevalent in astrocytic membranes at the blood-brain and brain-liquor interfaces. While AQP4 has been implicated in a number of pathophysiological processes, its role in brain physiology has remained elusive. Only recently has evidence accumulated to suggest that AQP4 is involved in such diverse functions as regulation of extracellular space volume, potassium buffering, cerebrospinal fluid circulation, interstitial fluid resorption, waste clearance, neuroinflammation, osmosensation, cell migration, and Ca 2ϩ signaling. AQP4 is also required for normal function of the retina, inner ear, and olfactory system. A review will be provided of the physiological roles of AQP4 in brain and of the growing list of data that emphasize the polarized nature of astrocytes.

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Section: Regulationmentioning

confidence: 99%

Physiological Roles of Aquaporin-4 in Brain

Nagelhus

Ottersen

2013

Physiological Reviews

579

520

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“…Water diffusion is altered by the structures of gray matter (12). DWI can be used to evaluate morphological changes in cortical microstructures (13)(14)(15)(16)(17)(18)(19) and can function as a probe to estimate immediate and transient changes in water diffusion that are associated with ischemia (17) or neuronal firing (13,16,19) and delayed and persistent changes that are associated with long-term plasticity in experimental settings (20) or pathological conditions (15,18,21). Here, using DWI techniques, we examined whether subthreshold, low-frequency (<1 Hz) rTMS to the left primary motor cortex (M1), a protocol that induces LTD-like plasticity (22, 23), increased water diffusion in the left M1 and other regions after the end of rTMS.…”

mentioning

confidence: 99%

Water diffusion reveals networks that modulate multiregional morphological plasticity after repetitive brain stimulation

Abe

Fukuyama

Mima

2014

Proc. Natl. Acad. Sci. U.S.A.

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Repetitive brain stimulation protocols induce plasticity in the stimulated site in brain slice models. Recent evidence from network models has indicated that additional plasticity-related changes occur in nonstimulated remote regions. Despite increasing use of brain stimulation protocols in experimental and clinical settings, the neural substrates underlying the additional effects in remote regions are unknown. Diffusion-weighted MRI (DWI) probes water diffusion and can be used to estimate morphological changes in cortical tissue that occur with the induction of plasticity. Using DWI techniques, we estimated morphological changes induced by application of repetitive transcranial magnetic stimulation (rTMS) over the left primary motor cortex (M1). We found that rTMS altered water diffusion in multiple regions including the left M1. Notably, the change in water diffusion was retained longest in the left M1 and remote regions that had a correlation of baseline fluctuations in water diffusion before rTMS. We conclude that synchronization of water diffusion at rest between stimulated and remote regions ensures retention of rTMS-induced changes in water diffusion in remote regions. Synchronized fluctuations in the morphology of cortical microstructures between stimulated and remote regions might identify networks that allow retention of plasticityrelated morphological changes in multiple regions after brain stimulation protocols. These results increase our understanding of the effects of brain stimulation-induced plasticity on multiregional brain networks. DWI techniques could provide a tool to evaluate treatment effects of brain stimulation protocols in patients with brain disorders.R epetitive electrical brain stimulation induces long-term potentiation (LTP) or depression (LTD) at the stimulated neurons (1-4). In humans, repetitive transcranial magnetic stimulation (rTMS) alters cortical excitability at the stimulated site that outlasts the end of the stimulation, analogous to LTP or LTD in animal models (5, 6), but also affects remote regions, possibly through transsynaptic pathways (7,8). Although rTMS has been proposed as a potential treatment for neurological and psychiatric disorders (9, 10) and as a method to facilitate learning (11), the neural substrates underlying the effects of rTMS on remote regions of the brain remain poorly understood.Diffusion-weighted MRI (DWI) probes water diffusion, a thermal physical phenomena that is characterized by random motion of water molecules (12). Water diffusion is altered by the structures of gray matter (12). DWI can be used to evaluate morphological changes in cortical microstructures (13)(14)(15)(16)(17)(18)(19) and can function as a probe to estimate immediate and transient changes in water diffusion that are associated with ischemia (17) or neuronal firing (13,16,19) and delayed and persistent changes that are associated with long-term plasticity in experimental settings (20) or pathological conditions (15,18,21). Here, using DWI techniques, we examined whether subt...

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“…Specifically, AQP4 was first mainly located on astrocyte end-feet, but was later distributed over the whole membrane of astrocytes. 130 These results also suggest that upregulated AQP4 expression is a physiological adaptation to induced hydrocephalus, possibly to aid and facilitate removal of excess water.…”

Section: 81mentioning

confidence: 76%

Hydrocephalus: the role of cerebral aquaporin-4 channels and computational modeling considerations of cerebrospinal fluid

Desai¹,

Hsu

Schneller

et al. 2016

FOC

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Aquaporin-4 (AQP4) channels play an important role in brain water homeostasis. Water transport across plasma membranes has a critical role in brain water exchange of the normal and the diseased brain. AQP4 channels are implicated in the pathophysiology of hydrocephalus, a disease of water imbalance that leads to CSF accumulation in the ventricular system. Many molecular aspects of fluid exchange during hydrocephalus have yet to be firmly elucidated, but review of the literature suggests that modulation of AQP4 channel activity is a potentially attractive future pharmaceutical therapy. Drug therapy targeting AQP channels may enable control over water exchange to remove excess CSF through a molecular intervention instead of by mechanical shunting. This article is a review of a vast body of literature on the current understanding of AQP4 channels in relation to hydrocephalus, details regarding molecular aspects of AQP4 channels, possible drug development strategies, and limitations. Advances in medical imaging and computational modeling of CSF dynamics in the setting of hydrocephalus are summarized. Algorithmic developments in computational modeling continue to deepen the understanding of the hydrocephalus disease process and display promising potential benefit as a tool for physicians to evaluate patients with hydrocephalus.

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Aquaporin 4 correlates with apparent diffusion coefficient and hydrocephalus severity in the rat brain: A combined MRI–histological study

Cited by 93 publications

References 26 publications

Physiological Roles of Aquaporin-4 in Brain

Physiological Roles of Aquaporin-4 in Brain

Water diffusion reveals networks that modulate multiregional morphological plasticity after repetitive brain stimulation

Hydrocephalus: the role of cerebral aquaporin-4 channels and computational modeling considerations of cerebrospinal fluid

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