Brain-wide changes in microglial morphology following peripheral nerve injury

Area of Science:

• Neuroscience
• Immunology
• Pain Research

Background:

• Neuropathic pain involves sensory, cognitive, and affective disruptions.
• Microglial reactivity is key in pain development, but brain patterns over time are unclear.

Purpose of the Study:

• To map time-dependent microglial morphological changes in the brain after peripheral nerve injury.
• To identify brain regions and circuits affected by microglial responses to injury.

Main Methods:

• Adult rats underwent chronic constriction injury (CCI) or sham surgery.
• Brain microglial morphology (CD11b+) was analyzed at 7 and 28 days post-surgery in 52 regions.
• Morphological measures and network analysis were performed using HALO software and graph theory.

Main Results:

• Significant injury and time-dependent effects on microglial morphology were observed across brain regions.
• Region-specific changes occurred in areas like the anterior cingulate cortex, amygdala, and hypothalamus.
• Network analysis revealed a shift in brain circuit hubs from day 7 to day 28, with declining connectivity over time.

Conclusions:

• Chronic neuropathic pain dynamically alters central microglial signaling in a region- and circuit-specific manner.
• These findings are relevant to pain chronification and associated comorbidities.
• The study provides a comprehensive map of microglial morphology in pain-processing brain areas.