Cerebral Water Content in Silicone Oil-Induced Hydrocephalic Rabbits

Bigio, Marc R. Del; Bruni, Edward

doi:10.1159/000120304

Cited by 35 publications

(9 citation statements)

References 25 publications

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“…Similar conclusions have been drawn by Rubin et al [25]. Del Bigio and Bruni [26], Bruni and Del Bigio [27] and McLone et al [28], Therefore, there has been a general understanding that changes in the water content of the periventricular white matter are in good correlation with ventricular and ECS size. However, the water content of the animals in both groups with ineffec tive shunt remained increased in spite of a reduction in ECS.…”

Section: Discussionsupporting

confidence: 83%

Morphological Analysis of Progressive Hydrocephalus and Shunt-Dependent Arrested Hydrocephalus

Takei

Satō²

1995

Pediatr Neurosurg

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This experimental study was performed to determine if surgically treated feline hydrocephalus could produce any morphological and physiological changes in the periventricular tissue. The result was analyzed with clinical outcome, comparing two differently prepared models in which the biomechanical characteristics of the container property of the brain were altered. Craniectomies were performed in adult mongrel cats and the dura mater was left untouched in group A, while the dura was incised in crucial fashion in groub B. Thirty-four animals underwent ventriculopleural shunt surgery 6–8 weeks after kaolin induction into the cisterna magna. In 19 animals, no shunt was implanted; they served as sham controls. These and 10 normal animals were subjected to transmission electron microscopic study or measurement of white matter water content. The regions studied were divided into three sections according to their depth from the ventricular surface (Wl, W2 and W3). Considering the efficacy of shunting, the increased water content observed in preshunt animals decreased and was almost identical to normal controls after effective diversion surgery. On the other hand, the animals with ineffective shunt failed to normalize the water content and the figures were similar to the time-matched sham animals. These trends were preserved in groups A and B, but water content was much higher in group B. On histological observation, the chronological profile of subependymal extracellular space (Wl, W2) in chronic condition did not correspond to the chronological changes in water content, while both changes observed after successful shunt were apparently linked. Subependymal glial proliferation was increased in volume as a function of time in all animals observed, but this was much more marked in group A than group B. Furthermore, gliosis was more evident in shunted animals than in the other group and was more prominent in cats with effective shunts than in those with ineffective shunts. These histological changes and clinical outcome were not closely related in this study. These results indicated that: (1) The shunting procedure itself could promote subependymal gliosis and this progresses unexpectedly even if CSF pressure is low enough after effective shunting. (2) This histological change is not necessarily a sufficient explanation for clinical improvement after successful shunting. (3) A biomechanical characteristic of the differently treated container property of the brain exerts an influence on the histological change and change in CSF dynamics in periependymal tissue mostly at an early stage of hydrocephalus rather than at a later stage. Therefore early treatment should be considered while avoiding an overindication for shunting.

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Section: Discussionsupporting

confidence: 83%

Morphological Analysis of Progressive Hydrocephalus and Shunt-Dependent Arrested Hydrocephalus

Takei

Satō²

1995

Pediatr Neurosurg

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“…Absolute water content measurements cannot be made accurately on such small samples [39]. Because of the small size of the rat brain, our density measurements lacked the anatomical precision previously needed to determine differences between gray and white matter of hydrocephalic rabbits [1]. In general the values we obtained in the MR experiments correspond well to previously published values, although we cannot explain why the ADCx and ADCy exhibited different temporal variations.…”

Section: Discussionmentioning

confidence: 59%

“…The gradients were calibrated using colored beads with densities of 1.018, 1.033, 1.049 and 1.062 g/ml (Percoll Density Marker Bead Kit; Sigma-Aldrich). The previously frozen samples were allowed to warm slightly and a cylindrical core was obtained using a cooled (-20°C) stainless steel tissue punch (inner diameter 4 mm) attached to a micrometer [1]. The micrometer allowed 1 mm-thick frozen slices to be shaved off the sample.…”

Section: Methodsmentioning

confidence: 99%

“…It has been inferred from computed tomography (CT), magnetic resonance (MR), tissue density (specific gravity) measurements, and electrical impedance studies in humans and experimental animals that compression of brain gray matter occurs at the expense of tissue water content [1-4]. Furthermore, experimental tracer studies show impaired diffusion through cortical gray matter [5,6] and ultrastructural studies show compression of the extracellular compartment in the outer cortical layers [7,8].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic resonance imaging indicators of blood-brain barrier and brain water changes in young rats with kaolin-induced hydrocephalus

Bigio

Slobodian

Schellenberg

et al. 2011

Fluids Barriers CNS

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BackgroundHydrocephalus is associated with enlargement of cerebral ventricles. We hypothesized that magnetic resonance (MR) imaging parameters known to be influenced by tissue water content would change in parallel with ventricle size in young rats and that changes in blood-brain barrier (BBB) permeability would be detected.MethodsHydrocephalus was induced by injection of kaolin into the cisterna magna of 4-week-old rats, which were studied 1 or 3 weeks later. MR was used to measure longitudinal and transverse relaxation times (T1 and T2) and apparent diffusion coefficients in several regions. Brain tissue water content was measured by the wet-dry weight method, and tissue density was measured in Percoll gradient columns. BBB permeability was measured by quantitative imaging of changes on T1-weighted images following injection of gadolinium diethylenetriamine penta-acetate (Gd-DTPA) tracer and microscopically by detection of fluorescent dextran conjugates.ResultsIn nonhydrocephalic rats, water content decreased progressively from age 3 to 7 weeks. T1 and T2 and apparent diffusion coefficients did not exhibit parallel changes and there was no evidence of BBB permeability to tracers. The cerebral ventricles enlarged progressively in the weeks following kaolin injection. In hydrocephalic rats, the dorsal cortex was more dense and the white matter less so, indicating that the increased water content was largely confined to white matter. Hydrocephalus was associated with transient elevation of T1 in gray and white matter and persistent elevation of T2 in white matter. Changes in the apparent diffusion coefficients were significant only in white matter. Ventricle size correlated significantly with dorsal water content, T1, T2, and apparent diffusion coefficients. MR imaging showed evidence of Gd-DTPA leakage in periventricular tissue foci but not diffusely. These correlated with microscopic leak of larger dextran tracers.ConclusionsMR characteristics cannot be used as direct surrogates for water content in the immature rat model of hydrocephalus, probably because they are also influenced by other changes in tissue composition that occur during brain maturation. There is no evidence for widespread persistent opening of BBB as a consequence of hydrocephalus in young rats. However, increase in focal BBB permeability suggests that periventricular blood vessels may be disrupted.

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“…(1976) suggested that hydrocephalic compression of the brain would force extracellular water out of the brain . Evidence in support of this comes from measurements of brain water content, tissue density (specific gravity) (Del Bigio & Bruni, 1987), opacity to X‐rays (Penn & Bacus, 1984), freeze‐substitution electron microscopy of the cerebral cortex (McLone et al ., 1973), and electrical impedance (Higashi et al ., 1989), although not all experiments of the latter type are in agreement (Grasso et al ., 2002). In the white matter, water content is increased (Hochwald et al ., 1975).…”

Section: Introductionmentioning

confidence: 99%

Aquaporin 4 changes in rat brain with severe hydrocephalus

Mao

Enno

Bigio

2006

Eur J of Neuroscience

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Hydrocephalus is characterized by impaired cerebrospinal fluid (CSF) flow with enlargement of the ventricular cavities of the brain and progressive damage to surrounding tissue. Bulk water movement is altered in these brains. We hypothesized that increased expression of aquaporins, which are water-permeable channel proteins, would occur in these brains to facilitate water shifts. We used quantitative (real-time) RT-PCR, Western blotting and immunohistochemistry to evaluate the brain expression of aquaporins (AQP) 1, 4, and 9 mRNA and protein in Sprague-Dawley rats rendered hydrocephalic by injection of kaolin into cistern magna. AQP4 mRNA was significantly up-regulated in parietal cerebrum and hippocampus 4 weeks and 9 months after induction of hydrocephalus (P < 0.05). Although Western blot analysis showed no significant change, there was more intense perivascular AQP4 immunoreactivity in cerebrum of hydrocephalic brains at 3-4 weeks after induction. We did not detect mRNA or protein changes in AQP1 (located in choroid plexus) or AQP9 (located in select neuron populations). Kir4.1, a potassium channel protein linked to water flux, exhibited enhanced immunoreactivity in the cerebral cortex of hydrocephalic rats; the perineuronal distribution was entirely different from that of AQP4. These results suggest that brain AQP4 up-regulation might be a compensatory response to maintain water homeostasis in hydrocephalus.

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Cerebral Water Content in Silicone Oil-Induced Hydrocephalic Rabbits

Cited by 35 publications

References 25 publications

Morphological Analysis of Progressive Hydrocephalus and Shunt-Dependent Arrested Hydrocephalus

Morphological Analysis of Progressive Hydrocephalus and Shunt-Dependent Arrested Hydrocephalus

Magnetic resonance imaging indicators of blood-brain barrier and brain water changes in young rats with kaolin-induced hydrocephalus

Aquaporin 4 changes in rat brain with severe hydrocephalus

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