Developmental study of the gene expression for alpha and gamma subunits of enolase in the rat brain by in situ hybridization histochemistry.

The gene expression for alpha and gamma subunits of enolase, a dimeric enzyme in the glycolytic pathway, was examined in the developing brain of rats by in situ hybridization. The expression for the gamma subunit of enolase was first detected in post-mitotic neurons settled in the mantle zone at E13, and it increased progressively until the adult stage. Expression signals for the alpha subunit were discerned in two discrete regions showing different developmental changes: the signals in the proliferative ventricular zone were intense at E13 and decreased and eventually disappeared around birth, whereas the signals in the mantle zone persisted until the adult stage. In the adult brain, mRNAs for the alpha and gamma subunits were expressed widely in neurons, resulting in almost similar temporal patterns in the brain except for the cerebellum. Expression levels of the alpha subunit in adult glial cells were below the detection threshold of the in situ hybridization analysis. These findings suggest that both alpha and gamma enolase subunits participate in energy production in neurons of the mature brain and that marked changes in the subunit composition of enolase occur according to both neuron type and maturation.