Previous studies using light and electron microscopy indicated a reduction of lipofuscin in the neurons of CNS and dorsal root ganglia in guinea pigs, rats and mice by treatment with centrophenoxine. The objective of the proposed project is to determine whether the drug reduces pigment formation or stops it completely in young mice and whether it can eliminate pigment already formed in the neurons of older animals. Young and old mice will be treated with centrophenoxine for variable periods, and animals of the same age, sex and inbred strain without treatment will be used as controls. Lipofuscin pigment will be isolated from the brain materials by biochemical method and the acid phosphatase content in the pigment will be quantitated by spectrophotometry. The amount of lipofuscin in a unit sample of the brain will be calculated from the amount of acid phosphatase. EM studies on the isolated pigment will be carried out to demonstrate any ultrastructural change due to the drug and also to judge the purity of the material. The present study will indicate the precise effect of centrophenoxine on the lipofuscin pigment in the brain.