Allopurinol treatment changes microglial characteristics in neonatal mice.

Microglia are resident immune cells that play crucial roles in regulating brain development. During the pre and postnatal stage, microglial morphology gradually alters by the elongation of processes and an increase in the number of branches. Previously, we reported that hypoxanthine, a key intermediate of the purine metabolism, affects the morphology of microglial cell line BV2. In this study, we show that administration of allopurinol, an inhibitor of xanthine oxidase, changes microglial morphology in vivo . We found that the number of branches and summed length of processes are increased in allopurinol-treated microglia in a sex-independent manner. Notably, allopurinol administration altered the number of IBA1-positive microglia in male mice. These findings suggest that purine metabolism contributes to the regulation of microglial characteristics during neonatal brain development.