MICROGLIA RESPONSES IN THE CNS FOLLOWING SCIATIC-NERVE TRANSECTION INC57BL WLD(S) AND BALB/C MICE/

The present study employed C57BL/Wld(s) mice to investigate whether a delay in microglia reaction would occur similar to the delay that occu rs in macrophage response after sciatic neurectomy. The results were c ompared with control BALB/c mice. The observations showed that in both strains of mice there was no delayed microglia response around lesion ed motoneurons and around the central processes of the dorsal root gan glion cells after sciatic neurectomy in the adult. The increased Mac-1 staining appeared as early as 1 day postoperation (dpo). This indicat es that microglial cells and macrophages respond to different signals generated by neurectomy. In both strains of mice, the number of microg lia in the neonate was much less than that in the adult and the increa se in Mac-1 staining was detectable only at 3 dpo in both strains of m ice. A significant loss of motoneurons was detected after sciatic neur ectomy in the neonate. However, there were no significant differences in the mean percentages of motoneuron loss between the two strains of mice at 5, 10, and 15 dpo. It is surmised that the lack of an adequate number of mature microglia in the neonates and their tardy expression of CR3 antigenicity may contribute to the motoneuron loss. (C) 1997 A cademic Press.