Developmental profile of three enolase isozymes in rat brain determination from one-cell embryo to adult brain.

Levels of three enolase isozymes (??, ?? and ??) were determined in rat tissues from one-cell embryo to adult brain with a sensitive enzyme immunoassay system. Each embryo of the early stage (gestational age, 0-3 days) contained about 5 x 10(?17) mol of ?? enolase. The nervous system-specific ?? and ?? enolases would be detected in the embryos of 6-8 days, which contain no histologically recognizable neurones. The 8-day embryos contained 4.3 x 10(?17) and 3.4 x 10(?16) mol of ?? and ?? enolases. Amounts of all the three enolases were increased with growth of the embryo. The nervous system-specific enolases (?? and ??) in the brain kept increasing until 1-2 months of postnatal age, whereas the ?? enolase level in the brain was relatively constant after the 15-day embryo through the adult rat.