Development of enolase isoenzymes in various regions of the human brain.

Various brain regions from 4 fetuses (21st to 28th gestational week) and from a 3-month-old infant were investigated for the total enolase activity and their isoenzyme distribution. In the brain tissue from a 3-month-old infant, the activity of the so-called neuron-specific enolase amounted to about 50% of the total enolase activity. In various brain regions different developmental patterns emerged for nonneuronal (NNE) and neuron-specific enolase (NSE). By the 21st gestational week the medulla, pons and thalamus had already reached a relatively high NSE activity (about 60-90% of that of the 3-month values), whereas the cortex regions had 10-30% only. It is concluded that in phylogenetically old regions, the switch from NNE to NSE-subunits appears before the 21st gestational week, in the phylogenetically young regions between the 21st and 28th gestational week.