REGIONAL CHANGES IN CNS LEVELS OF THE S‐100 AND 14‐3‐2 PROTEINS DURING DEVELOPMENT AND AGING OF THE MOUSE1

Abstract The levels of the S‐100 and 14‐3‐2 proteins were determined in a number of regions of mouse brain at intervals from 1 day to 30 months of age. Both S‐100 and 14‐3‐2 were found in measurable amounts as early as the first day of postnatal age but did not begin to accumulate rapidly in the forebrain, brain stem and cerebellum of the mouse brain until some time between the 7th and 14th days. From days 14 to 28 the levels of S‐100 and 14‐3‐2 in each region continued to increase rapidly with the exception of the forebrain where the rate of accumulation of S‐100 appeared to lag considerably behind that in the other regions. The proteins continued to accumulate at a rapid rate until approximately 6 months of age. From 6 to 30 months of age, the levels of 14‐3‐2 remained relatively stable in cerebellum, hippocampus and hypothalamus and appeared to decrease slightly in striatum and cerebral cortex. In the case of S‐100, the level of the protein increased in all regions of brain from 6 to 30 months but the increase was most pronounced in the hippocampus, hypothalamus and striatum. The principal conclusion derived from this study is that the biochemical development and aging of the central nervous system are regionally selective processes.