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Published on: January 30, 2014
Dexmedetomidine Alleviates Microglia-Induced Spinal Inflammation and Hyperalgesia in Neonatal Rats by Systemic
Wen Wen1,2, Xingrui Gong3, Hoiyin Cheung4
1Department of Anesthesiology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Abstract:
Noxious stimulus and painful experience in early life can induce cognitive deficits and abnormal pain sensitivity. As a major component of the outer membrane of gram-negative bacteria, lipopolysaccharide (LPS) injection mimics clinical symptoms of bacterial infections. Spinal microglial activation and the production of pro-inflammatory cytokines have been implicated in the pathogenesis of LPS-induced hyperalgesia in neonatal rats. Dexmedetomidine (DEX) possesses potent anti-neuroinflammatory and neuroprotective properties through the inhibition of microglial activation and microglial polarization toward pro-inflammatory (M1) phenotype and has been widely used in pediatric clinical practice. However, little is known about the effects of DEX on LPS-induced spinal inflammation and hyperalgesia in neonates. Here, we investigated whether systemic LPS exposure has persistent effects on spinal inflammation and hyperalgesia in neonatal rats and explored the protective role of DEX in adverse effects caused by LPS injection. Systemic LPS injections induced acute mechanical hyperalgesia, increased levels of pro-inflammatory cytokines in serum, and short-term increased expressions of pro-inflammatory cytokines and M1 microglial markers in the spinal cord of neonatal rats. Pretreatment with DEX significantly decreased inflammation and alleviated mechanical hyperalgesia induced by LPS. The inhibition of M1 microglial polarization and microglial pro-inflammatory cytokines expression in the spinal cord may implicate its neuroprotective effect, which highlights a new therapeutic target in the treatment of infection-induced hyperalgesia in neonates and preterm infants.
Insights
Early life exposure to lipopolysaccharide (LPS) causes pain sensitivity. Dexmedetomidine (DEX) protects against LPS-induced spinal inflammation and hyperalgesia in neonatal rats.
Area of Science:
- Neuroscience
- Immunology
- Pharmacology
Background:
- Early life noxious stimuli can lead to cognitive deficits and altered pain sensitivity.
- Lipopolysaccharide (LPS) injection models bacterial infections, causing spinal microglial activation and pro-inflammatory cytokine production, contributing to hyperalgesia.
- Dexmedetomidine (DEX) is known for anti-neuroinflammatory and neuroprotective effects by inhibiting microglial activation.
Purpose of the Study:
- To investigate the persistent effects of LPS on spinal inflammation and hyperalgesia in neonatal rats.
- To explore the protective role of DEX against LPS-induced adverse effects in neonates.
- To elucidate the mechanisms underlying DEX's neuroprotection in LPS-exposed neonatal rats.
Main Methods:
- Neonatal rats were administered LPS to induce hyperalgesia and inflammation.
- Dexmedetomidine (DEX) was used as a pre-treatment to assess its protective effects.
- Levels of pro-inflammatory cytokines and M1 microglial markers in serum and spinal cord were measured.
Main Results:
- LPS injection induced mechanical hyperalgesia, increased serum pro-inflammatory cytokines, and transiently elevated spinal pro-inflammatory cytokines and M1 microglial markers.
- Pre-treatment with DEX significantly reduced inflammation and alleviated LPS-induced mechanical hyperalgesia.
- DEX inhibited M1 microglial polarization and pro-inflammatory cytokine expression in the spinal cord.
Conclusions:
- Systemic LPS exposure causes short-term spinal inflammation and hyperalgesia in neonatal rats.
- Dexmedetomidine (DEX) demonstrates a neuroprotective effect by mitigating LPS-induced spinal inflammation and hyperalgesia.
- Inhibiting M1 microglial polarization is a potential therapeutic mechanism for DEX in treating infection-induced hyperalgesia in neonates.
