Differences in distribution and regulation of astrocytic aquaporin-4 in human and rat hydrocephalic brain

TY - JOUR

T1 - Differences in distribution and regulation of astrocytic aquaporin-4 in human and rat hydrocephalic brain

AU - Skjolding, Anders Daehli

AU - Holst, Anders Vedel

AU - Broholm, Helle

AU - Laursen, Henning

AU - Juhler, Marianne

N1 - © 2012 The Authors. Neuropathology and Applied Neurobiology © 2012 British Neuropathological Society.

PY - 2013/2

Y1 - 2013/2

N2 - Aims: Aquaporin-4 (AQP4) is the most abundant cellular water channel in brain and could be a molecular basis for a cerebrospinal fluid absorption route additional to the arachnoid villi. In the search for 'alternative' cerebrospinal fluid absorption pathways it is important to compare experimental findings with human pathophysiology. This study compares expression of AQP4 in hydrocephalic human brain with human controls and hydrocephalic rat brain. Methods: Cortical biopsies from patients with chronic hydrocephalus (n=29) were sampled secondary to planned surgical intervention. AQP4 in human hydrocephalic cortex relative to controls was quantified by Western blotting (n=28). A second biopsy (n=13) was processed for immunohistochemistry [glial fibrillary acidic protein (GFAP), CD68, CD34 and AQP4] and double immunofluorescence (AQP4+GFAP and AQP4+CD34). Brain tissue from human controls and kaolin-induced hydrocephalic rats was processed in parallel. Immunohistochemistry and immunofluorescence were assessed qualitatively. Results: Western blotting showed that AQP4 abundance was significantly increased (P<0.05) in hydrocephalic human brain compared with controls. AQP4 immunoreactivity was present in both white and grey matter. In human brain (hydrocephalic and controls) AQP4 immunoreactivity was found on the entire astrocyte membrane, unlike hydrocephalic rat brain where pronounced endfeet polarization was present. Endothelial AQP4 immunoreactivity was not observed. Conclusions: This study shows a significant increase in astrocytic AQP4 in human hydrocephalic cortex compared with control. Cell type specific expression in astrocytes is conserved between rat and human, although differences of expression in specific membrane domains are seen. This study addresses direct translational aspects from rat to human, hereby emphasizing the relevance and use of models in hydrocephalus research.

AB - Aims: Aquaporin-4 (AQP4) is the most abundant cellular water channel in brain and could be a molecular basis for a cerebrospinal fluid absorption route additional to the arachnoid villi. In the search for 'alternative' cerebrospinal fluid absorption pathways it is important to compare experimental findings with human pathophysiology. This study compares expression of AQP4 in hydrocephalic human brain with human controls and hydrocephalic rat brain. Methods: Cortical biopsies from patients with chronic hydrocephalus (n=29) were sampled secondary to planned surgical intervention. AQP4 in human hydrocephalic cortex relative to controls was quantified by Western blotting (n=28). A second biopsy (n=13) was processed for immunohistochemistry [glial fibrillary acidic protein (GFAP), CD68, CD34 and AQP4] and double immunofluorescence (AQP4+GFAP and AQP4+CD34). Brain tissue from human controls and kaolin-induced hydrocephalic rats was processed in parallel. Immunohistochemistry and immunofluorescence were assessed qualitatively. Results: Western blotting showed that AQP4 abundance was significantly increased (P<0.05) in hydrocephalic human brain compared with controls. AQP4 immunoreactivity was present in both white and grey matter. In human brain (hydrocephalic and controls) AQP4 immunoreactivity was found on the entire astrocyte membrane, unlike hydrocephalic rat brain where pronounced endfeet polarization was present. Endothelial AQP4 immunoreactivity was not observed. Conclusions: This study shows a significant increase in astrocytic AQP4 in human hydrocephalic cortex compared with control. Cell type specific expression in astrocytes is conserved between rat and human, although differences of expression in specific membrane domains are seen. This study addresses direct translational aspects from rat to human, hereby emphasizing the relevance and use of models in hydrocephalus research.

U2 - 10.1111/j.1365-2990.2012.01275.x

DO - 10.1111/j.1365-2990.2012.01275.x

M3 - Journal article

C2 - 22497211

SN - 0305-1846

VL - 39

SP - 179

EP - 191

JO - Neuropathology and Applied Neurobiology

JF - Neuropathology and Applied Neurobiology

IS - 2

ER -