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Published on: June 10, 2013
Dexmedetomidine Mitigates Microglial Activation Associated with Postoperative Cognitive Dysfunction by Modulating the
Zhichao Wu1,2, Han Wang2, Zuan Shi2
1Department of Anesthesiology, The First Affiliated Hospital of Jinan University, Guangzhou, 510630 Guangdong, China.
Abstract:
Surgery-induced microglial activation is critical in mediating postoperative cognitive dysfunction (POCD) in elderly patients, where the important protective effect of dexmedetomidine has been indicated. However, the mechanisms of action of dexmedetomidine during the neuroinflammatory response that underlies POCD remain largely unknown. We found that lipopolysaccharide (LPS) induced substantial inflammatory responses in primary and BV2 microglial cells. The screening of differentially expressed miRNAs revealed that miR-103a-3p was downregulated in these cell culture models. Overexpression of miR-103a-3p mimics and inhibitors suppressed and enhanced the release of inflammatory factors, respectively. VAMP1 expression was upregulated in LPS-treated primary and BV-2 microglial cells, and it was validated as a downstream target of miR-103-3p. VAMP1-knockdown significantly inhibited the LPS-induced inflammatory response. Dexmedetomidine treatment markedly inhibited LPS-induced inflammation and the expression of VAMP1, and miR-103a-3p expression reversed this inhibition. Moreover, dexmedetomidine mitigated microglial activation and the associated inflammatory response in a rat model of surgical trauma that mimicked POCD. In this model, dexmedetomidine reversed miR-103a-3p and VAMP1 expression; this effect was abolished by miR-103a-3p overexpression. Taken together, the data show that miR-103a-3p/VAMP1 is critical for surgery-induced microglial activation of POCD.
Insights
Dexmedetomidine protects against postoperative cognitive dysfunction by inhibiting microglial activation. It achieves this by regulating the miR-103a-3p/VAMP1 pathway, crucial for neuroinflammation.
Area of Science:
- Neuroscience
- Immunology
- Pharmacology
Background:
- Surgery can trigger microglial activation, leading to postoperative cognitive dysfunction (POCD) in elderly patients.
- Dexmedetomidine shows protective effects against POCD, but its underlying mechanisms in neuroinflammation are unclear.
Purpose of the Study:
- To elucidate the role of dexmedetomidine in modulating neuroinflammation and microglial activation in POCD.
- To identify key molecular pathways, including microRNAs (miRNAs) and their targets, involved in dexmedetomidine's protective effects.
Main Methods:
- Utilized lipopolysaccharide (LPS) to induce inflammatory responses in primary and BV2 microglial cells.
- Screened for differentially expressed miRNAs, identifying miR-103a-3p.
- Validated VAMP1 as a downstream target of miR-103a-3p.
- Employed a rat model of surgical trauma to mimic POCD, assessing dexmedetomidine's effects in vivo.
Main Results:
- LPS upregulated VAMP1 and downregulated miR-103a-3p in microglial cells.
- Overexpression of miR-103a-3p suppressed inflammation; VAMP1 knockdown inhibited LPS-induced inflammatory response.
- Dexmedetomidine inhibited LPS-induced inflammation and VAMP1 expression, an effect reversed by miR-103a-3p overexpression.
- In vivo, dexmedetomidine mitigated microglial activation and inflammation, reversing altered miR-103a-3p and VAMP1 expression.
Conclusions:
- The miR-103a-3p/VAMP1 axis is critical in surgery-induced microglial activation contributing to POCD.
- Dexmedetomidine exerts neuroprotective effects by targeting the miR-103a-3p/VAMP1 pathway, suppressing neuroinflammation.
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