Abstract
The effect of spinal cord injury (SCI) on the expression levels and distribution of water channel aquaporin 4 (AQP4) has not been studied. We have found AQP4 in gray and white matter astrocytes in both uninjured and injured rat spinal cords. AQP4 was detected in astrocytic processes that were tightly surrounding neurons and blood vessels, but more robustly in glia limitans externa and interna, which were forming an interface between spinal cord parenchyma and cerebrospinal fluid (CSF). Such spatial distribution of AQP4 suggests a critical role that astrocytes expressing AQP4 play in the transport of water from blood/CSF to spinal cord parenchyma and vice versa. SCI induced biphasic changes in astrocytic AQP4 levels, including its early down-regulation and subsequent persistent up-regulation. However, changes in AQP4 expression did not correlate well with the onset and magnitude of astrocytic activation, when measured as changes in GFAP expression levels. It appears that reactive astrocytes began expressing increased levels of AQP4 after migrating to the wound area (thoracic region) two weeks after SCI, and AQP4 remained significantly elevated for months after SCI. We also showed that increased levels of AQP4 spread away from the lesion site to cervical and lumbar segments, but only in chronically injured spinal cords. Although overall AQP4 expression levels increased in chronically-injured spinal cords, AQP4 immunolabeling in astrocytic processes forming glia limitans externa was decreased, which may indicate impaired water transport through glia limitans externa. Finally, we also showed that SCI-induced changes in AQP4 protein levels correlate, both temporally and spatially, with persistent increases in water content in acutely and chronically injured spinal cords. Although correlative, this finding suggests a possible link between AQP4 and impaired water transport/edema/syringomyelia in contused spinal cords.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 779-792 |
| Number of pages | 14 |
| Journal | Neuroscience |
| Volume | 143 |
| Issue number | 3 |
| DOIs | |
| State | Published - Dec 13 2006 |
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Keywords
- aquaporin 4
- astrocytes
- glia limitans
- spinal cord injury
- water content
ASJC Scopus subject areas
- Neuroscience(all)
Cite this
Acute and chronic changes in aquaporin 4 expression after spinal cord injury. / Nesic, O.; Lee, J.; Ye, Z.; Unabia, G. C.; Rafati, D.; Hulsebosch, C. E.; Perez-Polo, J. R.
In: Neuroscience, Vol. 143, No. 3, 13.12.2006, p. 779-792.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Acute and chronic changes in aquaporin 4 expression after spinal cord injury
AU - Nesic, O.
AU - Lee, J.
AU - Ye, Z.
AU - Unabia, G. C.
AU - Rafati, D.
AU - Hulsebosch, C. E.
AU - Perez-Polo, J. R.
PY - 2006/12/13
Y1 - 2006/12/13
N2 - The effect of spinal cord injury (SCI) on the expression levels and distribution of water channel aquaporin 4 (AQP4) has not been studied. We have found AQP4 in gray and white matter astrocytes in both uninjured and injured rat spinal cords. AQP4 was detected in astrocytic processes that were tightly surrounding neurons and blood vessels, but more robustly in glia limitans externa and interna, which were forming an interface between spinal cord parenchyma and cerebrospinal fluid (CSF). Such spatial distribution of AQP4 suggests a critical role that astrocytes expressing AQP4 play in the transport of water from blood/CSF to spinal cord parenchyma and vice versa. SCI induced biphasic changes in astrocytic AQP4 levels, including its early down-regulation and subsequent persistent up-regulation. However, changes in AQP4 expression did not correlate well with the onset and magnitude of astrocytic activation, when measured as changes in GFAP expression levels. It appears that reactive astrocytes began expressing increased levels of AQP4 after migrating to the wound area (thoracic region) two weeks after SCI, and AQP4 remained significantly elevated for months after SCI. We also showed that increased levels of AQP4 spread away from the lesion site to cervical and lumbar segments, but only in chronically injured spinal cords. Although overall AQP4 expression levels increased in chronically-injured spinal cords, AQP4 immunolabeling in astrocytic processes forming glia limitans externa was decreased, which may indicate impaired water transport through glia limitans externa. Finally, we also showed that SCI-induced changes in AQP4 protein levels correlate, both temporally and spatially, with persistent increases in water content in acutely and chronically injured spinal cords. Although correlative, this finding suggests a possible link between AQP4 and impaired water transport/edema/syringomyelia in contused spinal cords.
AB - The effect of spinal cord injury (SCI) on the expression levels and distribution of water channel aquaporin 4 (AQP4) has not been studied. We have found AQP4 in gray and white matter astrocytes in both uninjured and injured rat spinal cords. AQP4 was detected in astrocytic processes that were tightly surrounding neurons and blood vessels, but more robustly in glia limitans externa and interna, which were forming an interface between spinal cord parenchyma and cerebrospinal fluid (CSF). Such spatial distribution of AQP4 suggests a critical role that astrocytes expressing AQP4 play in the transport of water from blood/CSF to spinal cord parenchyma and vice versa. SCI induced biphasic changes in astrocytic AQP4 levels, including its early down-regulation and subsequent persistent up-regulation. However, changes in AQP4 expression did not correlate well with the onset and magnitude of astrocytic activation, when measured as changes in GFAP expression levels. It appears that reactive astrocytes began expressing increased levels of AQP4 after migrating to the wound area (thoracic region) two weeks after SCI, and AQP4 remained significantly elevated for months after SCI. We also showed that increased levels of AQP4 spread away from the lesion site to cervical and lumbar segments, but only in chronically injured spinal cords. Although overall AQP4 expression levels increased in chronically-injured spinal cords, AQP4 immunolabeling in astrocytic processes forming glia limitans externa was decreased, which may indicate impaired water transport through glia limitans externa. Finally, we also showed that SCI-induced changes in AQP4 protein levels correlate, both temporally and spatially, with persistent increases in water content in acutely and chronically injured spinal cords. Although correlative, this finding suggests a possible link between AQP4 and impaired water transport/edema/syringomyelia in contused spinal cords.
KW - aquaporin 4
KW - astrocytes
KW - glia limitans
KW - spinal cord injury
KW - water content
UR - http://www.scopus.com/inward/record.url?scp=33751021655&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33751021655&partnerID=8YFLogxK
U2 - 10.1016/j.neuroscience.2006.08.079
DO - 10.1016/j.neuroscience.2006.08.079
M3 - Article
C2 - 17074445
AN - SCOPUS:33751021655
VL - 143
SP - 779
EP - 792
JO - Neuroscience
JF - Neuroscience
SN - 0306-4522
IS - 3
ER -