MACROPHAGE AND MICROGLIAL CELL RESPONSE AFTER COMMON PERONEAL NERVE CUT AND CRUSH IN C57BL 6J MICE/

The present study, using Mac-1 immunohistochemistry for the detection of macrophages and microglial cells, has investigated the signals for macrophage recruitment in the peripheral nerve fibres and dorsal root ganglia, and microglial cell activation in the dorsal and ventral horn s of the spinal cord, at different periods after a right common perone al (CP) nerve cut or crush in 86 C57BL/6J mice. Though a previous stud y has demonstrated a delayed regeneration of the peripheral sensory bu t not the motor fibres in this strain of mice, the present study could not demonstrate a corresponding delay in macrophage recruitment in th e L4-L6 dorsal root ganglia and microglial cell activation in the dors al and ventral horns of the corresponding segments of the spinal cord. In fact, macrophage recruitment and microglial cell activation appear ed a short time after the nerve lesion and peaked at 5 days post-opera tion then subsequently declined. Microglial cells, however, became rea ctivated at 20-30 days after CP nerve cut perhaps because of the prese nce of newly degenerated fibres. In contrast to the above observation, there was no exuberant macrophage recruitment or microglial cell reac tion during the period when the majority of the regenerated fibres wer e detected in the distal segment of the crushed nerve. (C) 1996 Academ ic Press Limited.