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The role of TNF-α in regulating ketamine-induced hippocampal neurotoxicity.

Zheng X, Zhou J, Xia Y - Arch Med Sci (2015)

Bottom Line: In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity.This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesia, Zhejiang Hospital, Hangzhou, Zhejiang, China.

ABSTRACT

Introduction: Ketamine is commonly used in pediatric anesthesia but recent studies have shown that it could induce neurotoxicity in the developing brain. The inflammatory cytokine, tumor necrosis factor α (TNF-α) is involved in the pathogenesis of various types of neurodegenerations. In the present study, we examined whether TNF-α may regulate ketamine-induced neurotoxicity in the hippocampus of neonatal mouse.

Material and methods: The in vitro organotypic culture of hippocampal slices was used to investigate the gain-of-function and loss-of-function effect of TNF-α modulation on ketamine-induced hippocampal neurotoxicity. Also, western blotting analysis was used to examine the relative pathways associated with TNF-α modulation. In the in vivo Morris water maze test, TNF-α was genetically silenced to see if memory function was improved after anesthesia-induced memory impairment.

Results: In in vitro experiments, adding TNF-α enhanced (112.99 ±5.4%, p = 0.015), whereas knocking down TNF-α ameliorated (46.8 ±11.6%, p = 0.003) ketamine-induced apoptosis in hippocampal CA1 neurons in the organotypic culture. Western blotting showed that addition of TNF-α reduced (67.1 ±3.7%, p = 0.022), whereas downregulation of TNF-α increased (126.87 ±8.5%, p = 0.004) the phosphorylation of PKC-ERK pathway in ketamine-treated hippocampus. In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.

Conclusions: Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity. This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.

No MeSH data available.


Related in: MedlinePlus

TNF-α regulated PKC-ERK signaling pathway during ketamine-induced neurotoxicity in vitro. A – Western blotting analysis of the protein expression levels of phosphorylated PKC (p-PKC) and phosphorylated ERK (p-ERK) for the organotypic hippocampal slice cultures that were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. B – Semi-quantitative measurements of the protein densities when hippocampal cultures were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. *P < 0.05, as compared to control, ▵p < 0.05, as compared to ketamine treatment (n = 3)
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Figure 0002: TNF-α regulated PKC-ERK signaling pathway during ketamine-induced neurotoxicity in vitro. A – Western blotting analysis of the protein expression levels of phosphorylated PKC (p-PKC) and phosphorylated ERK (p-ERK) for the organotypic hippocampal slice cultures that were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. B – Semi-quantitative measurements of the protein densities when hippocampal cultures were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. *P < 0.05, as compared to control, ▵p < 0.05, as compared to ketamine treatment (n = 3)

Mentions: Previous studied demonstrated that the PKC-ERK pathway was downregulated during the process of ketamine-mediated neuronal death in the hippocampus [9, 11]. As we discovered that TNF-α played an important role in regulating ketamine-induced neurotoxicity in the hippocampus, we turned to biochemistry to investigate whether TNF-α modulated hippocampal apoptosis through the PKC-ERK signaling pathway. Our western blotting assay showed that adding a compound of TNF-α to the ketamine-treated hippocampal culture further reduced the protein expression of phosphorylated ERK (p-ERK) and phosphorylated PKC (p-PKC), whereas silencing TNF-α upregulated the expression of p-ERK and p-PKC (Figure 2 A). Quantitative analysis showed that the attenuating and augmenting effects of TNF-α on PKC pathway related proteins were significant (Figure 2 B).


The role of TNF-α in regulating ketamine-induced hippocampal neurotoxicity.

Zheng X, Zhou J, Xia Y - Arch Med Sci (2015)

TNF-α regulated PKC-ERK signaling pathway during ketamine-induced neurotoxicity in vitro. A – Western blotting analysis of the protein expression levels of phosphorylated PKC (p-PKC) and phosphorylated ERK (p-ERK) for the organotypic hippocampal slice cultures that were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. B – Semi-quantitative measurements of the protein densities when hippocampal cultures were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. *P < 0.05, as compared to control, ▵p < 0.05, as compared to ketamine treatment (n = 3)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4697060&req=5

Figure 0002: TNF-α regulated PKC-ERK signaling pathway during ketamine-induced neurotoxicity in vitro. A – Western blotting analysis of the protein expression levels of phosphorylated PKC (p-PKC) and phosphorylated ERK (p-ERK) for the organotypic hippocampal slice cultures that were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. B – Semi-quantitative measurements of the protein densities when hippocampal cultures were treated with control medium, ketamine only, ketamine + TNF-α, or ketamine + TNF-α siRNA. *P < 0.05, as compared to control, ▵p < 0.05, as compared to ketamine treatment (n = 3)
Mentions: Previous studied demonstrated that the PKC-ERK pathway was downregulated during the process of ketamine-mediated neuronal death in the hippocampus [9, 11]. As we discovered that TNF-α played an important role in regulating ketamine-induced neurotoxicity in the hippocampus, we turned to biochemistry to investigate whether TNF-α modulated hippocampal apoptosis through the PKC-ERK signaling pathway. Our western blotting assay showed that adding a compound of TNF-α to the ketamine-treated hippocampal culture further reduced the protein expression of phosphorylated ERK (p-ERK) and phosphorylated PKC (p-PKC), whereas silencing TNF-α upregulated the expression of p-ERK and p-PKC (Figure 2 A). Quantitative analysis showed that the attenuating and augmenting effects of TNF-α on PKC pathway related proteins were significant (Figure 2 B).

Bottom Line: In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity.This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesia, Zhejiang Hospital, Hangzhou, Zhejiang, China.

ABSTRACT

Introduction: Ketamine is commonly used in pediatric anesthesia but recent studies have shown that it could induce neurotoxicity in the developing brain. The inflammatory cytokine, tumor necrosis factor α (TNF-α) is involved in the pathogenesis of various types of neurodegenerations. In the present study, we examined whether TNF-α may regulate ketamine-induced neurotoxicity in the hippocampus of neonatal mouse.

Material and methods: The in vitro organotypic culture of hippocampal slices was used to investigate the gain-of-function and loss-of-function effect of TNF-α modulation on ketamine-induced hippocampal neurotoxicity. Also, western blotting analysis was used to examine the relative pathways associated with TNF-α modulation. In the in vivo Morris water maze test, TNF-α was genetically silenced to see if memory function was improved after anesthesia-induced memory impairment.

Results: In in vitro experiments, adding TNF-α enhanced (112.99 ±5.4%, p = 0.015), whereas knocking down TNF-α ameliorated (46.8 ±11.6%, p = 0.003) ketamine-induced apoptosis in hippocampal CA1 neurons in the organotypic culture. Western blotting showed that addition of TNF-α reduced (67.1 ±3.7%, p = 0.022), whereas downregulation of TNF-α increased (126.87 ±8.5%, p = 0.004) the phosphorylation of PKC-ERK pathway in ketamine-treated hippocampus. In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.

Conclusions: Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity. This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.

No MeSH data available.


Related in: MedlinePlus