A regional study of the molecular forms of acetylcholinesterase in the brain of developing and adult rats.

This study of the molecular forms of acetylcholinesterase in several rat brain regions using sucrose gradient centrifugation has revealed only two major forms throughout postnatal development: the 4S and 10S. In all regions studied (cerebral cortex, cerebellum, caudate nucleus, hippocampus, pons-medulla and superior colliculi), enzyme activity progresses from high 4S/low 10S activity at birth to the converse in the adult. The 10S, the major form in mature brain, is not proportionally greater at birth in areas which are phylogenetically older. Study of cerebral cortex and cerebellum at 1, 13, 19-20 postnatal days and in the adult shows a nonlinear shift from the 4S form to the 10S form with a decrease or leveling off of 10S (in specific activity and total amount) prior to attaining the high adult levels. We suggest a possible relation of our findings to certain histogenic events in the brain.