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Inhibitory effects of ketamine on lipopolysaccharide-induced microglial activation.

Chang Y, Lee JJ, Hsieh CY, Hsiao G, Chou DS, Sheu JR - Mediators Inflamm. (2009)

Bottom Line: In this study, we found that ketamine (100 and 250 microM) concentration-dependently inhibited lipopolysaccharide (LPS)-induced NO and IL-1beta release in primary cultured microglia.However, ketamine (100 and 250 microM) did not significantly inhibit the LPS-induced TNF-alpha production in microglia, except at the higher concentration (500 microM).These results suggest that microglial inactivation by ketamine is at least partially due to inhibition of ERK1/2 phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, School of Medicine, Fu-Jen Catholic University, 24205 Taipei, Taiwan.

ABSTRACT
Microglia activated in response to brain injury release neurotoxic factors including nitric oxide (NO) and proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). Ketamine, an anesthetic induction agent, is generally reserved for use in patients with severe hypotension or respiratory depression. In this study, we found that ketamine (100 and 250 microM) concentration-dependently inhibited lipopolysaccharide (LPS)-induced NO and IL-1beta release in primary cultured microglia. However, ketamine (100 and 250 microM) did not significantly inhibit the LPS-induced TNF-alpha production in microglia, except at the higher concentration (500 microM). Further study of the molecular mechanisms revealed that ketamine markedly inhibited extracellular signal-regulated kinase (ERK1/2) phosphorylation but not c-Jun N-terminal kinase or p38 mitogen-activated protein kinase stimulated by LPS in microglia. These results suggest that microglial inactivation by ketamine is at least partially due to inhibition of ERK1/2 phosphorylation.

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Related in: MedlinePlus

Effect of ketamine on nitrite formationin LPS-activated microglia. Microglia (5 × 105 cells mL−1)  were treated with ketamine (100 and 250 μM) or an isovolumetric PBS buffer for 30 minutes, followed bythe addition of LPS (100 ng mL−1) for 24 hours. Cell-freesupernatants were assayed for nitrite production as described in Section 2. Data are presented as the means ± S.E.M. (n = 3). **P < .01, compared to theresting group; ##P < .01, compared tothe PBS-treated group.
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fig1: Effect of ketamine on nitrite formationin LPS-activated microglia. Microglia (5 × 105 cells mL−1) were treated with ketamine (100 and 250 μM) or an isovolumetric PBS buffer for 30 minutes, followed bythe addition of LPS (100 ng mL−1) for 24 hours. Cell-freesupernatants were assayed for nitrite production as described in Section 2. Data are presented as the means ± S.E.M. (n = 3). **P < .01, compared to theresting group; ##P < .01, compared tothe PBS-treated group.

Mentions: According to a preliminarytest, activation of microglia by LPS (100 ng mL−1) induced a significantand marked increase in nitrite formation. Therefore, an LPS concentration of 100 ng mL−1 was employed in the following experiments. Inthis study, the concentration of nitrite produced in the cell supernatanttime-dependently increased from 0.5 ± 0.0 (resting) to 6.7 ± 0.3 μM at 24 hours after LPS treatment (Figure 1). Ketamine (100 and 250 μM) concentration-dependently inhibited LPS-(100 ng mL−1) stimulated nitrite production byapproximately 40% and 60%, respectively, (Figure 1). Ketamine neither interferedwith the Griess reaction nor reacted with native NO (data not shown). Theseresults demonstrate that ketamine markedly suppressed NO production stimulatedby LPS in microglia. Furthermore, neither ketamine (100 ~ 500 μM) (Figure 2) nor LPS (100 ng mL−1) (data not shown) significantly affectedthe cell viability of microglia for 24 hours according to the MTT assay.


Inhibitory effects of ketamine on lipopolysaccharide-induced microglial activation.

Chang Y, Lee JJ, Hsieh CY, Hsiao G, Chou DS, Sheu JR - Mediators Inflamm. (2009)

Effect of ketamine on nitrite formationin LPS-activated microglia. Microglia (5 × 105 cells mL−1)  were treated with ketamine (100 and 250 μM) or an isovolumetric PBS buffer for 30 minutes, followed bythe addition of LPS (100 ng mL−1) for 24 hours. Cell-freesupernatants were assayed for nitrite production as described in Section 2. Data are presented as the means ± S.E.M. (n = 3). **P < .01, compared to theresting group; ##P < .01, compared tothe PBS-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2662525&req=5

fig1: Effect of ketamine on nitrite formationin LPS-activated microglia. Microglia (5 × 105 cells mL−1) were treated with ketamine (100 and 250 μM) or an isovolumetric PBS buffer for 30 minutes, followed bythe addition of LPS (100 ng mL−1) for 24 hours. Cell-freesupernatants were assayed for nitrite production as described in Section 2. Data are presented as the means ± S.E.M. (n = 3). **P < .01, compared to theresting group; ##P < .01, compared tothe PBS-treated group.
Mentions: According to a preliminarytest, activation of microglia by LPS (100 ng mL−1) induced a significantand marked increase in nitrite formation. Therefore, an LPS concentration of 100 ng mL−1 was employed in the following experiments. Inthis study, the concentration of nitrite produced in the cell supernatanttime-dependently increased from 0.5 ± 0.0 (resting) to 6.7 ± 0.3 μM at 24 hours after LPS treatment (Figure 1). Ketamine (100 and 250 μM) concentration-dependently inhibited LPS-(100 ng mL−1) stimulated nitrite production byapproximately 40% and 60%, respectively, (Figure 1). Ketamine neither interferedwith the Griess reaction nor reacted with native NO (data not shown). Theseresults demonstrate that ketamine markedly suppressed NO production stimulatedby LPS in microglia. Furthermore, neither ketamine (100 ~ 500 μM) (Figure 2) nor LPS (100 ng mL−1) (data not shown) significantly affectedthe cell viability of microglia for 24 hours according to the MTT assay.

Bottom Line: In this study, we found that ketamine (100 and 250 microM) concentration-dependently inhibited lipopolysaccharide (LPS)-induced NO and IL-1beta release in primary cultured microglia.However, ketamine (100 and 250 microM) did not significantly inhibit the LPS-induced TNF-alpha production in microglia, except at the higher concentration (500 microM).These results suggest that microglial inactivation by ketamine is at least partially due to inhibition of ERK1/2 phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, School of Medicine, Fu-Jen Catholic University, 24205 Taipei, Taiwan.

ABSTRACT
Microglia activated in response to brain injury release neurotoxic factors including nitric oxide (NO) and proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). Ketamine, an anesthetic induction agent, is generally reserved for use in patients with severe hypotension or respiratory depression. In this study, we found that ketamine (100 and 250 microM) concentration-dependently inhibited lipopolysaccharide (LPS)-induced NO and IL-1beta release in primary cultured microglia. However, ketamine (100 and 250 microM) did not significantly inhibit the LPS-induced TNF-alpha production in microglia, except at the higher concentration (500 microM). Further study of the molecular mechanisms revealed that ketamine markedly inhibited extracellular signal-regulated kinase (ERK1/2) phosphorylation but not c-Jun N-terminal kinase or p38 mitogen-activated protein kinase stimulated by LPS in microglia. These results suggest that microglial inactivation by ketamine is at least partially due to inhibition of ERK1/2 phosphorylation.

Show MeSH
Related in: MedlinePlus