Alendronate Attenuates Spinal Microglial Activation and Neuropathic Pain

Area of Science:

• Neuroscience
• Pharmacology
• Cell Biology

Background:

• Bisphosphonates inhibit bone resorption and are used for bone-related diseases.
• The pain-relieving mechanism of bisphosphonates is not fully understood.
• Previous studies suggest bisphosphonates may affect neurochemical changes in bone cancer pain.

Purpose of the Study:

• To investigate if bisphosphonates inhibit spinal microglial activation and prevent hyperalgesia from peripheral tissue injury.
• To examine the effects of alendronate on neuropathic pain and microglial activation in vivo and in vitro.

Main Methods:

• Alendronate administered intrathecally and intraperitoneally in a rat model of chronic constriction sciatic nerve injury.
• Assessed neuropathic pain behaviors, spinal microglial activation, and astrocyte changes.
• In vitro studies on primary microglia stimulated with lipopolysaccharide to evaluate alendronate's effect on signaling pathways and cytokine expression.

Main Results:

• Alendronate administration significantly relieved neuropathic pain behaviors.
• Alendronate attenuated spinal microglial activation and p38 MAPK phosphorylation but did not affect astrocytes.
• In vitro, alendronate reduced phosphorylated p38 and extracellular signal-regulated kinase (ERK) in microglia and decreased inflammatory cytokine expression.

Conclusions:

• Alendronate effectively relieves neuropathic pain induced by chronic constriction sciatic nerve injury.
• The pain relief is associated with the inhibition of spinal microglial activation and the p38 MAPK signaling pathway.
• These findings suggest potential therapeutic applications for alendronate in neuropathic pain beyond bone metabolism-related diseases.