HYDROGEN-PEROXIDE ENHANCES PHAGOCYTIC-ACTIVITY OF AMEBOID MICROGLIA

Microglia are considered to serve as a guardian of the brain. In achie ving this task, they have been observed to transform into a reactive f orm and then an ameboid form. Several substances are implicated in the control of such behavior. We examined the effect of hydrogen peroxide on cultured microglia of ameboid form obtained from the fetal rat bra in employing video-enhanced contrast-differential interference contras t microscopy. Microglia harvested from the culture bottle were observe d to float in a spherical shape with abundant filopodia on the surface . However, on coming into contact with the glass surface of a cover sl ip, they immediately transformed into an ameboid form. The microglia s pread themselves out, surrounded by thin transparent lammellipodia, wh ich would not be clearly observable by either light microscopy or elec tron microscopy, In a concentration-dependent fashion, 10(-3)-10(-1) M hydrogen peroxide solution enhanced the ruffling process of the lamel lipodia and formation of vesicles (phagosomes), which displayed a typi cal phagocytotic form. It is concluded that an increase in free radica ls in ischemic tissue tends to facilitate the phagocytosis of ameboid microglia as macrophages. (C) 1998 Elsevier Science Ireland Ltd.