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Signaling function of Na,K-ATPase induced by ouabain against LPS as an inflammation model in hippocampus.

Kinoshita PF, Yshii LM, Vasconcelos AR, Orellana AM, Lima Lde S, Davel AP, Rossoni LV, Kawamoto EM, Scavone C - J Neuroinflammation (2014)

Bottom Line: The involvement of the inflammatory transcription factor NF-κB in the OUA effect was indicated by its prevention of LPS-induced nuclear translocation of the NF-κB subunit, RELA (p65), as well as the decreased cytosol levels of the NF-κB inhibitor, IKB, in the hippocampus.Our results suggest that a low dose of OUA has an important anti-inflammatory effect in the rat hippocampus.This effect was associated with decreased GFAP induction by LPS in the dentate gyrus, a brain area linked to adult neurogenesis.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neuropharmacology Laboratory, Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, 05508-900, São Paulo, Brazil. paula.f.kinoshita@gmail.com.

ABSTRACT

Background: Ouabain (OUA) is a newly recognized hormone that is synthesized in the adrenal cortex and hypothalamus. Low doses of OUA can activate a signaling pathway by interaction with Na,K-ATPase, which is protective against a number of insults. OUA has central and peripheral anti-inflammatory effects. Lipopolysaccharide (LPS), via toll-like receptor 4 activation, is a widely used model to induce systemic inflammation. This study used a low OUA dose to evaluate its effects on inflammation induced by LPS injection in rats.

Methods: Adult male Wistar rats received acute intraperitoneal (ip) OUA (1.8 μg/kg) or saline 20 minutes before LPS (200 μg/kg, ip) or saline injection. Some of the animals had their femoral artery catheterized in order to assess arterial blood pressure values before and after OUA administration. Na,K-ATPase activity, cytokine mRNA levels, apoptosis-related proteins, NF-κB activation brain-derived neurotrophic factor BDNF, corticosterone and TNF-α levels were measured.

Results: OUA pretreatment decreased mRNA levels of the pro-inflammatory cytokines, inducible nitric oxide synthase (iNOS) and IL-1β, which are activated by LPS in the hippocampus, but with no effect on serum measures of these factors. None of these OUA effects were linked to Na,K-ATPase activity. The involvement of the inflammatory transcription factor NF-κB in the OUA effect was indicated by its prevention of LPS-induced nuclear translocation of the NF-κB subunit, RELA (p65), as well as the decreased cytosol levels of the NF-κB inhibitor, IKB, in the hippocampus. OUA pretreatment reversed the LPS-induced glial fibrillary acidic protein (GFAP) activation and associated inflammation in the dentate gyrus. OUA also prevented LPS-induced increases in the hippocampal Bax/Bcl2 ratio suggesting an anti-apoptotic action in the brain.

Conclusion: Our results suggest that a low dose of OUA has an important anti-inflammatory effect in the rat hippocampus. This effect was associated with decreased GFAP induction by LPS in the dentate gyrus, a brain area linked to adult neurogenesis.

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Effects of ouabain (OUA) pretreatment(1.8 μg/kg)on lipopolysaccharide (LPS)-induced(200 μg/kg)regulation of hippocampal brain-derived neurotrophic factor (BDNF) and TNF-α levels. (A) The levels of BDNF were decreased in LPS and OUA groups in comparison with control and OUA + LPS group, aP < 0.05 versus control and LPS and bP < 0.01 versus control and OUA + LPS and P < 0.05 versus OUA. (B) The levels of TNF-α in the hippocampus, aP < 0.01 versus control and OUA + LPS and bP < 0.05 versus control and OUA + LPS. Data are presented as mean ± SEM from five individual experiments. One-way ANOVA followed by Newman-Keuls test.
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Fig6: Effects of ouabain (OUA) pretreatment(1.8 μg/kg)on lipopolysaccharide (LPS)-induced(200 μg/kg)regulation of hippocampal brain-derived neurotrophic factor (BDNF) and TNF-α levels. (A) The levels of BDNF were decreased in LPS and OUA groups in comparison with control and OUA + LPS group, aP < 0.05 versus control and LPS and bP < 0.01 versus control and OUA + LPS and P < 0.05 versus OUA. (B) The levels of TNF-α in the hippocampus, aP < 0.01 versus control and OUA + LPS and bP < 0.05 versus control and OUA + LPS. Data are presented as mean ± SEM from five individual experiments. One-way ANOVA followed by Newman-Keuls test.

Mentions: OUA or LPS alone significantly decreased BDNF in comparison to controls, although the decrease induced by LPS was significantly greater. However, OUA pretreatment reversed LPS effects, leading to BDNF levels at that of controls (Figure 6A). Likewise, LPS or OUA treatment alone increased the inflammatory cytokine, TNF-α, with OUA pretreatment preventing LPS-induced TNF-α increases versus control (Figure 6B).Figure 6


Signaling function of Na,K-ATPase induced by ouabain against LPS as an inflammation model in hippocampus.

Kinoshita PF, Yshii LM, Vasconcelos AR, Orellana AM, Lima Lde S, Davel AP, Rossoni LV, Kawamoto EM, Scavone C - J Neuroinflammation (2014)

Effects of ouabain (OUA) pretreatment(1.8 μg/kg)on lipopolysaccharide (LPS)-induced(200 μg/kg)regulation of hippocampal brain-derived neurotrophic factor (BDNF) and TNF-α levels. (A) The levels of BDNF were decreased in LPS and OUA groups in comparison with control and OUA + LPS group, aP < 0.05 versus control and LPS and bP < 0.01 versus control and OUA + LPS and P < 0.05 versus OUA. (B) The levels of TNF-α in the hippocampus, aP < 0.01 versus control and OUA + LPS and bP < 0.05 versus control and OUA + LPS. Data are presented as mean ± SEM from five individual experiments. One-way ANOVA followed by Newman-Keuls test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307894&req=5

Fig6: Effects of ouabain (OUA) pretreatment(1.8 μg/kg)on lipopolysaccharide (LPS)-induced(200 μg/kg)regulation of hippocampal brain-derived neurotrophic factor (BDNF) and TNF-α levels. (A) The levels of BDNF were decreased in LPS and OUA groups in comparison with control and OUA + LPS group, aP < 0.05 versus control and LPS and bP < 0.01 versus control and OUA + LPS and P < 0.05 versus OUA. (B) The levels of TNF-α in the hippocampus, aP < 0.01 versus control and OUA + LPS and bP < 0.05 versus control and OUA + LPS. Data are presented as mean ± SEM from five individual experiments. One-way ANOVA followed by Newman-Keuls test.
Mentions: OUA or LPS alone significantly decreased BDNF in comparison to controls, although the decrease induced by LPS was significantly greater. However, OUA pretreatment reversed LPS effects, leading to BDNF levels at that of controls (Figure 6A). Likewise, LPS or OUA treatment alone increased the inflammatory cytokine, TNF-α, with OUA pretreatment preventing LPS-induced TNF-α increases versus control (Figure 6B).Figure 6

Bottom Line: The involvement of the inflammatory transcription factor NF-κB in the OUA effect was indicated by its prevention of LPS-induced nuclear translocation of the NF-κB subunit, RELA (p65), as well as the decreased cytosol levels of the NF-κB inhibitor, IKB, in the hippocampus.Our results suggest that a low dose of OUA has an important anti-inflammatory effect in the rat hippocampus.This effect was associated with decreased GFAP induction by LPS in the dentate gyrus, a brain area linked to adult neurogenesis.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neuropharmacology Laboratory, Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, 05508-900, São Paulo, Brazil. paula.f.kinoshita@gmail.com.

ABSTRACT

Background: Ouabain (OUA) is a newly recognized hormone that is synthesized in the adrenal cortex and hypothalamus. Low doses of OUA can activate a signaling pathway by interaction with Na,K-ATPase, which is protective against a number of insults. OUA has central and peripheral anti-inflammatory effects. Lipopolysaccharide (LPS), via toll-like receptor 4 activation, is a widely used model to induce systemic inflammation. This study used a low OUA dose to evaluate its effects on inflammation induced by LPS injection in rats.

Methods: Adult male Wistar rats received acute intraperitoneal (ip) OUA (1.8 μg/kg) or saline 20 minutes before LPS (200 μg/kg, ip) or saline injection. Some of the animals had their femoral artery catheterized in order to assess arterial blood pressure values before and after OUA administration. Na,K-ATPase activity, cytokine mRNA levels, apoptosis-related proteins, NF-κB activation brain-derived neurotrophic factor BDNF, corticosterone and TNF-α levels were measured.

Results: OUA pretreatment decreased mRNA levels of the pro-inflammatory cytokines, inducible nitric oxide synthase (iNOS) and IL-1β, which are activated by LPS in the hippocampus, but with no effect on serum measures of these factors. None of these OUA effects were linked to Na,K-ATPase activity. The involvement of the inflammatory transcription factor NF-κB in the OUA effect was indicated by its prevention of LPS-induced nuclear translocation of the NF-κB subunit, RELA (p65), as well as the decreased cytosol levels of the NF-κB inhibitor, IKB, in the hippocampus. OUA pretreatment reversed the LPS-induced glial fibrillary acidic protein (GFAP) activation and associated inflammation in the dentate gyrus. OUA also prevented LPS-induced increases in the hippocampal Bax/Bcl2 ratio suggesting an anti-apoptotic action in the brain.

Conclusion: Our results suggest that a low dose of OUA has an important anti-inflammatory effect in the rat hippocampus. This effect was associated with decreased GFAP induction by LPS in the dentate gyrus, a brain area linked to adult neurogenesis.

Show MeSH