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Neuroinflammation increases GABAergic tone and impairs cognitive and motor function in hyperammonemia by increasing GAT-3 membrane expression. Reversal by sulforaphane by promoting M2 polarization of microglia.

Hernandez-Rabaza V, Cabrera-Pastor A, Taoro-Gonzalez L, Gonzalez-Usano A, Agusti A, Balzano T, Llansola M, Felipo V - J Neuroinflammation (2016)

Bottom Line: This is also associated with increased extracellular GABA in the cerebellum and with motor in-coordination and impaired learning ability in the Y maze.Sulforaphane promotes polarization of microglia from the M1 to the M2 phenotype, reducing IL-1b and increasing IL-4, IL-10, Arg1, and YM-1 in the cerebellum.This is associated with astrocytes deactivation and normalization of GAT-3 membrane expression, extracellular GABA, glutamate-nitric oxide-cGMP pathway, and learning and motor coordination.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe , Eduardo Primo Yúfera, 3, Valencia, 46012, Spain.

ABSTRACT

Background: Hyperammonemia induces neuroinflammation and increases GABAergic tone in the cerebellum which contributes to cognitive and motor impairment in hepatic encephalopathy (HE). The link between neuroinflammation and GABAergic tone remains unknown. New treatments reducing neuroinflammation and GABAergic tone could improve neurological impairment. The aims were, in hyperammonemic rats, to assess whether: (a) Enhancing endogenous anti-inflammatory mechanisms by sulforaphane treatment reduces neuroinflammation and restores learning and motor coordination. (b) Reduction of neuroinflammation by sulforaphane normalizes extracellular GABA and glutamate-NO-cGMP pathway and identify underlying mechanisms. (c) Identify steps by which hyperammonemia-induced microglial activation impairs cognitive and motor function and how sulforaphane restores them.

Methods: We analyzed in control and hyperammonemic rats, treated or not with sulforaphane, (a) learning in the Y maze; (b) motor coordination in the beam walking; (c) glutamate-NO-cGMP pathway and extracellular GABA by microdialysis; (d) microglial activation, by analyzing by immunohistochemistry or Western blot markers of pro-inflammatory (M1) (IL-1b, Iba-1) and anti-inflammatory (M2) microglia (Iba1, IL-4, IL-10, Arg1, YM-1); and (e) membrane expression of the GABA transporter GAT-3.

Results: Hyperammonemia induces activation of astrocytes and microglia in the cerebellum as assessed by immunohistochemistry. Hyperammonemia-induced neuroinflammation is associated with increased membrane expression of the GABA transporter GAT-3, mainly in activated astrocytes. This is also associated with increased extracellular GABA in the cerebellum and with motor in-coordination and impaired learning ability in the Y maze. Sulforaphane promotes polarization of microglia from the M1 to the M2 phenotype, reducing IL-1b and increasing IL-4, IL-10, Arg1, and YM-1 in the cerebellum. This is associated with astrocytes deactivation and normalization of GAT-3 membrane expression, extracellular GABA, glutamate-nitric oxide-cGMP pathway, and learning and motor coordination.

Conclusions: Neuroinflammation increases GABAergic tone in the cerebellum by increasing GAT-3 membrane expression. This impairs motor coordination and learning in the Y maze. Sulforaphane could be a new therapeutic approach to improve cognitive and motor function in hyperammonemia, hepatic encephalopathy, and other pathologies associated with neuroinflammation by promoting microglia differentiation from M1 to M2.

No MeSH data available.


Related in: MedlinePlus

IL-4, IL-10, and IL-1b are present both in microglia and astrocytes. The images show immunostaining by double fluorescence of astrocytes (GFAP) or microglia (Iba-1 or CD11b) and IL-4 (a–f); IL-10 (g–l), or IL-1b (m–r). Arrows indicate co-localization of the labeling of the IL with the corresponding cell type marker
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Fig7: IL-4, IL-10, and IL-1b are present both in microglia and astrocytes. The images show immunostaining by double fluorescence of astrocytes (GFAP) or microglia (Iba-1 or CD11b) and IL-4 (a–f); IL-10 (g–l), or IL-1b (m–r). Arrows indicate co-localization of the labeling of the IL with the corresponding cell type marker

Mentions: To assess in which cell types are IL-1b, IL-4, and IL-10 expressed, we performed co-localization studies by immunohistochemistry using antibodies against these ILs and against markers of astrocytes (GFAP) or microglia (Iba-1 and CD11B). The results are shown in Fig. 7. IL-4 co-localizes both with Iba-1 (Fig. 7a–c) and with GFAP (Fig. 7d–f) indicating that it is expressed both in astrocytes and in microglia. The same occurs with IL-10 and IL-1b, which co-localize both with microglia (Fig. 7g–i and m–o, respectively) and astrocytes (Fig. 7j–l and p–r, respectively). As shown in Fig. 6g, in hyperammonemic rats, IL-1b is increased in activated astrocytes and treatment with SFN reduces it.Fig. 7


Neuroinflammation increases GABAergic tone and impairs cognitive and motor function in hyperammonemia by increasing GAT-3 membrane expression. Reversal by sulforaphane by promoting M2 polarization of microglia.

Hernandez-Rabaza V, Cabrera-Pastor A, Taoro-Gonzalez L, Gonzalez-Usano A, Agusti A, Balzano T, Llansola M, Felipo V - J Neuroinflammation (2016)

IL-4, IL-10, and IL-1b are present both in microglia and astrocytes. The images show immunostaining by double fluorescence of astrocytes (GFAP) or microglia (Iba-1 or CD11b) and IL-4 (a–f); IL-10 (g–l), or IL-1b (m–r). Arrows indicate co-localization of the labeling of the IL with the corresponding cell type marker
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4835883&req=5

Fig7: IL-4, IL-10, and IL-1b are present both in microglia and astrocytes. The images show immunostaining by double fluorescence of astrocytes (GFAP) or microglia (Iba-1 or CD11b) and IL-4 (a–f); IL-10 (g–l), or IL-1b (m–r). Arrows indicate co-localization of the labeling of the IL with the corresponding cell type marker
Mentions: To assess in which cell types are IL-1b, IL-4, and IL-10 expressed, we performed co-localization studies by immunohistochemistry using antibodies against these ILs and against markers of astrocytes (GFAP) or microglia (Iba-1 and CD11B). The results are shown in Fig. 7. IL-4 co-localizes both with Iba-1 (Fig. 7a–c) and with GFAP (Fig. 7d–f) indicating that it is expressed both in astrocytes and in microglia. The same occurs with IL-10 and IL-1b, which co-localize both with microglia (Fig. 7g–i and m–o, respectively) and astrocytes (Fig. 7j–l and p–r, respectively). As shown in Fig. 6g, in hyperammonemic rats, IL-1b is increased in activated astrocytes and treatment with SFN reduces it.Fig. 7

Bottom Line: This is also associated with increased extracellular GABA in the cerebellum and with motor in-coordination and impaired learning ability in the Y maze.Sulforaphane promotes polarization of microglia from the M1 to the M2 phenotype, reducing IL-1b and increasing IL-4, IL-10, Arg1, and YM-1 in the cerebellum.This is associated with astrocytes deactivation and normalization of GAT-3 membrane expression, extracellular GABA, glutamate-nitric oxide-cGMP pathway, and learning and motor coordination.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Neurobiología, Centro Investigación Príncipe Felipe , Eduardo Primo Yúfera, 3, Valencia, 46012, Spain.

ABSTRACT

Background: Hyperammonemia induces neuroinflammation and increases GABAergic tone in the cerebellum which contributes to cognitive and motor impairment in hepatic encephalopathy (HE). The link between neuroinflammation and GABAergic tone remains unknown. New treatments reducing neuroinflammation and GABAergic tone could improve neurological impairment. The aims were, in hyperammonemic rats, to assess whether: (a) Enhancing endogenous anti-inflammatory mechanisms by sulforaphane treatment reduces neuroinflammation and restores learning and motor coordination. (b) Reduction of neuroinflammation by sulforaphane normalizes extracellular GABA and glutamate-NO-cGMP pathway and identify underlying mechanisms. (c) Identify steps by which hyperammonemia-induced microglial activation impairs cognitive and motor function and how sulforaphane restores them.

Methods: We analyzed in control and hyperammonemic rats, treated or not with sulforaphane, (a) learning in the Y maze; (b) motor coordination in the beam walking; (c) glutamate-NO-cGMP pathway and extracellular GABA by microdialysis; (d) microglial activation, by analyzing by immunohistochemistry or Western blot markers of pro-inflammatory (M1) (IL-1b, Iba-1) and anti-inflammatory (M2) microglia (Iba1, IL-4, IL-10, Arg1, YM-1); and (e) membrane expression of the GABA transporter GAT-3.

Results: Hyperammonemia induces activation of astrocytes and microglia in the cerebellum as assessed by immunohistochemistry. Hyperammonemia-induced neuroinflammation is associated with increased membrane expression of the GABA transporter GAT-3, mainly in activated astrocytes. This is also associated with increased extracellular GABA in the cerebellum and with motor in-coordination and impaired learning ability in the Y maze. Sulforaphane promotes polarization of microglia from the M1 to the M2 phenotype, reducing IL-1b and increasing IL-4, IL-10, Arg1, and YM-1 in the cerebellum. This is associated with astrocytes deactivation and normalization of GAT-3 membrane expression, extracellular GABA, glutamate-nitric oxide-cGMP pathway, and learning and motor coordination.

Conclusions: Neuroinflammation increases GABAergic tone in the cerebellum by increasing GAT-3 membrane expression. This impairs motor coordination and learning in the Y maze. Sulforaphane could be a new therapeutic approach to improve cognitive and motor function in hyperammonemia, hepatic encephalopathy, and other pathologies associated with neuroinflammation by promoting microglia differentiation from M1 to M2.

No MeSH data available.


Related in: MedlinePlus