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Targeted over-expression of endothelin-1 in astrocytes leads to more severe brain damage and vasospasm after subarachnoid hemorrhage.

Yeung PK, Shen J, Chung SS, Chung SK - BMC Neurosci (2013)

Bottom Line: The present study suggests that astrocytic ET-1 involves in SAH-induced cerebral injury, edema and vasospasm, through ETA receptor and PKC-mediated potassium channel dysfunction.Administration of ABT-627 (ETA receptor antagonist) and SR 49059 (vasopressin V1a receptor antagonist) resulted in amelioration of edema and vasospasm in mice following SAH.These data provide a strong rationale to investigate SR 49059 and ABT-627 as therapeutic drugs for the treatment of SAH patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China. skchung@hkucc.hku.hk.

ABSTRACT

Background: Endothelin-1 (ET-1) is a potent vasoconstrictor, and astrocytic ET-1 is reported to play a role in the pathogenesis of cerebral ischemic injury and cytotoxic edema. However, it is still unknown whether astrocytic ET-1 also contributes to vasogenic edema and vasospasm during subarachnoid hemorrhage (SAH). In the present study, transgenic mice with astrocytic endothelin-1 over-expression (GET-1 mice) were used to investigate the pathophysiological role of ET-1 in SAH pathogenesis.

Results: The GET-1 mice experienced a higher mortality rate and significantly more severe neurological deficits, blood-brain barrier breakdown and vasogenic edema compared to the non-transgenic (Ntg) mice following SAH. Oral administration of vasopressin V1a receptor antagonist, SR 49059, significantly reduced the cerebral water content in the GET-1 mice. Furthermore, the GET-1 mice showed significantly more pronounced middle cerebral arterial (MCA) constriction after SAH. Immunocytochemical analysis showed that the calcium-activated potassium channels and the phospho-eNOS were significantly downregulated, whereas PKC-α expression was significantly upregulated in the MCA of the GET-1 mice when compared to Ntg mice after SAH. Administration of ABT-627 (ETA receptor antagonist) significantly down-regulated PKC-α expression in the MCA of the GET-1 mice following SAH.

Conclusions: The present study suggests that astrocytic ET-1 involves in SAH-induced cerebral injury, edema and vasospasm, through ETA receptor and PKC-mediated potassium channel dysfunction. Administration of ABT-627 (ETA receptor antagonist) and SR 49059 (vasopressin V1a receptor antagonist) resulted in amelioration of edema and vasospasm in mice following SAH. These data provide a strong rationale to investigate SR 49059 and ABT-627 as therapeutic drugs for the treatment of SAH patients.

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GET-1 mice showed more severe brain edema with upregulation of ET-1 and GFAP expressions after subarachnoid hemorrhage. (A) Analysis the integrity of the BBB with the EB extravasation in Ntg and GET-1 brain after SAH. (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for the sham groups and n = 8 for the SAH groups). (B) Histogram comparing the water content of the Ntg and GET-1 mice with or without SR 49059 treatment after SAH (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice). (C) Immunocytochemical analysis of ET-1 expression in Ntg brain after SAH. Representative micrograph shows the expression of ET-1 in the hippocampal region of the Ntg brain after Sham (i) and SAH (ii) (n = 4 for each group). Histogram below shows the quantification results (relative value in percentage) of ET-1 Sham and SAH of Ntg brain sections using software ImageJ. (**P < 0.01, student t-test; n = 4 for each group of mice). (D) Immunocytochemical analysis of GFAP expression after SAH. Representative micrograph shows the localization and expression of GFAP in the astrocytes of the hippocampus of the Ntg and GET-1 brain at (i-iv) low and (v-viii) high magnification (n = 4 for each group). The GFAP signals in the astrocytes at the SAH groups of the Ntg and GET-1 brains is increased, and they have longer processes (arrowheads). Histogram below shows the quantification results (relative value in percentage) of GFAP Sham and SAH of Ntg and GET-1 brain sections using software ImageJ. (*P < 0.05, **P < 0.01, ***P < 0.005, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice).
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Figure 2: GET-1 mice showed more severe brain edema with upregulation of ET-1 and GFAP expressions after subarachnoid hemorrhage. (A) Analysis the integrity of the BBB with the EB extravasation in Ntg and GET-1 brain after SAH. (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for the sham groups and n = 8 for the SAH groups). (B) Histogram comparing the water content of the Ntg and GET-1 mice with or without SR 49059 treatment after SAH (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice). (C) Immunocytochemical analysis of ET-1 expression in Ntg brain after SAH. Representative micrograph shows the expression of ET-1 in the hippocampal region of the Ntg brain after Sham (i) and SAH (ii) (n = 4 for each group). Histogram below shows the quantification results (relative value in percentage) of ET-1 Sham and SAH of Ntg brain sections using software ImageJ. (**P < 0.01, student t-test; n = 4 for each group of mice). (D) Immunocytochemical analysis of GFAP expression after SAH. Representative micrograph shows the localization and expression of GFAP in the astrocytes of the hippocampus of the Ntg and GET-1 brain at (i-iv) low and (v-viii) high magnification (n = 4 for each group). The GFAP signals in the astrocytes at the SAH groups of the Ntg and GET-1 brains is increased, and they have longer processes (arrowheads). Histogram below shows the quantification results (relative value in percentage) of GFAP Sham and SAH of Ntg and GET-1 brain sections using software ImageJ. (*P < 0.05, **P < 0.01, ***P < 0.005, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice).

Mentions: To further understand the role of astrocytic ET-1 in SAH-induced neurological dysfunction in GET-1 mice, the BBB integrity in both Ntg and GET-1 mice was investigated with Evans Blue (EB) extravasation experiment (Figure 2A). At 24 hours after SAH, the amount of EB leakage was increased in NTg and GET-1 mice when compared with their sham groups. Most importantly, a significant elevation of EB leakage was observed in GET-1 brains (Ntg: 2.42 ± 0.54 μg/hemisphere vs GET-1: 5.74 ± 0.87 μg/hemisphere, n = 8, **P < 0.01 by Mann–Whitney test) (Figure 2A), indicating increased BBB permeability and more BBB breakdown in the brains of GET-1 mice after SAH.


Targeted over-expression of endothelin-1 in astrocytes leads to more severe brain damage and vasospasm after subarachnoid hemorrhage.

Yeung PK, Shen J, Chung SS, Chung SK - BMC Neurosci (2013)

GET-1 mice showed more severe brain edema with upregulation of ET-1 and GFAP expressions after subarachnoid hemorrhage. (A) Analysis the integrity of the BBB with the EB extravasation in Ntg and GET-1 brain after SAH. (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for the sham groups and n = 8 for the SAH groups). (B) Histogram comparing the water content of the Ntg and GET-1 mice with or without SR 49059 treatment after SAH (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice). (C) Immunocytochemical analysis of ET-1 expression in Ntg brain after SAH. Representative micrograph shows the expression of ET-1 in the hippocampal region of the Ntg brain after Sham (i) and SAH (ii) (n = 4 for each group). Histogram below shows the quantification results (relative value in percentage) of ET-1 Sham and SAH of Ntg brain sections using software ImageJ. (**P < 0.01, student t-test; n = 4 for each group of mice). (D) Immunocytochemical analysis of GFAP expression after SAH. Representative micrograph shows the localization and expression of GFAP in the astrocytes of the hippocampus of the Ntg and GET-1 brain at (i-iv) low and (v-viii) high magnification (n = 4 for each group). The GFAP signals in the astrocytes at the SAH groups of the Ntg and GET-1 brains is increased, and they have longer processes (arrowheads). Histogram below shows the quantification results (relative value in percentage) of GFAP Sham and SAH of Ntg and GET-1 brain sections using software ImageJ. (*P < 0.05, **P < 0.01, ***P < 0.005, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice).
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Figure 2: GET-1 mice showed more severe brain edema with upregulation of ET-1 and GFAP expressions after subarachnoid hemorrhage. (A) Analysis the integrity of the BBB with the EB extravasation in Ntg and GET-1 brain after SAH. (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for the sham groups and n = 8 for the SAH groups). (B) Histogram comparing the water content of the Ntg and GET-1 mice with or without SR 49059 treatment after SAH (*P < 0.05, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice). (C) Immunocytochemical analysis of ET-1 expression in Ntg brain after SAH. Representative micrograph shows the expression of ET-1 in the hippocampal region of the Ntg brain after Sham (i) and SAH (ii) (n = 4 for each group). Histogram below shows the quantification results (relative value in percentage) of ET-1 Sham and SAH of Ntg brain sections using software ImageJ. (**P < 0.01, student t-test; n = 4 for each group of mice). (D) Immunocytochemical analysis of GFAP expression after SAH. Representative micrograph shows the localization and expression of GFAP in the astrocytes of the hippocampus of the Ntg and GET-1 brain at (i-iv) low and (v-viii) high magnification (n = 4 for each group). The GFAP signals in the astrocytes at the SAH groups of the Ntg and GET-1 brains is increased, and they have longer processes (arrowheads). Histogram below shows the quantification results (relative value in percentage) of GFAP Sham and SAH of Ntg and GET-1 brain sections using software ImageJ. (*P < 0.05, **P < 0.01, ***P < 0.005, ANOVA followed by Bonferroni’s test; n = 4 for each group of mice).
Mentions: To further understand the role of astrocytic ET-1 in SAH-induced neurological dysfunction in GET-1 mice, the BBB integrity in both Ntg and GET-1 mice was investigated with Evans Blue (EB) extravasation experiment (Figure 2A). At 24 hours after SAH, the amount of EB leakage was increased in NTg and GET-1 mice when compared with their sham groups. Most importantly, a significant elevation of EB leakage was observed in GET-1 brains (Ntg: 2.42 ± 0.54 μg/hemisphere vs GET-1: 5.74 ± 0.87 μg/hemisphere, n = 8, **P < 0.01 by Mann–Whitney test) (Figure 2A), indicating increased BBB permeability and more BBB breakdown in the brains of GET-1 mice after SAH.

Bottom Line: The present study suggests that astrocytic ET-1 involves in SAH-induced cerebral injury, edema and vasospasm, through ETA receptor and PKC-mediated potassium channel dysfunction.Administration of ABT-627 (ETA receptor antagonist) and SR 49059 (vasopressin V1a receptor antagonist) resulted in amelioration of edema and vasospasm in mice following SAH.These data provide a strong rationale to investigate SR 49059 and ABT-627 as therapeutic drugs for the treatment of SAH patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China. skchung@hkucc.hku.hk.

ABSTRACT

Background: Endothelin-1 (ET-1) is a potent vasoconstrictor, and astrocytic ET-1 is reported to play a role in the pathogenesis of cerebral ischemic injury and cytotoxic edema. However, it is still unknown whether astrocytic ET-1 also contributes to vasogenic edema and vasospasm during subarachnoid hemorrhage (SAH). In the present study, transgenic mice with astrocytic endothelin-1 over-expression (GET-1 mice) were used to investigate the pathophysiological role of ET-1 in SAH pathogenesis.

Results: The GET-1 mice experienced a higher mortality rate and significantly more severe neurological deficits, blood-brain barrier breakdown and vasogenic edema compared to the non-transgenic (Ntg) mice following SAH. Oral administration of vasopressin V1a receptor antagonist, SR 49059, significantly reduced the cerebral water content in the GET-1 mice. Furthermore, the GET-1 mice showed significantly more pronounced middle cerebral arterial (MCA) constriction after SAH. Immunocytochemical analysis showed that the calcium-activated potassium channels and the phospho-eNOS were significantly downregulated, whereas PKC-α expression was significantly upregulated in the MCA of the GET-1 mice when compared to Ntg mice after SAH. Administration of ABT-627 (ETA receptor antagonist) significantly down-regulated PKC-α expression in the MCA of the GET-1 mice following SAH.

Conclusions: The present study suggests that astrocytic ET-1 involves in SAH-induced cerebral injury, edema and vasospasm, through ETA receptor and PKC-mediated potassium channel dysfunction. Administration of ABT-627 (ETA receptor antagonist) and SR 49059 (vasopressin V1a receptor antagonist) resulted in amelioration of edema and vasospasm in mice following SAH. These data provide a strong rationale to investigate SR 49059 and ABT-627 as therapeutic drugs for the treatment of SAH patients.

Show MeSH
Related in: MedlinePlus