EXISTENCE AND NEUROBIOLOGICAL SIGNIFICANCE OF NEURONAL AND GLIAL FORMS OF THE GLYCOLYTIC ENZYME ENOLASE

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 14  (4) , 563-579
Abstract
The isoenzymes of the glycolytic enzyme enolase were separated and purified. The structural and functional properties of 2 brain enolases in rats are described. Immunocytochemical techniques have established that 1 brain enolase is restricted to neuronal cells (neuron-specific enolase, NSE) while the other is localized in glial cells (nonneuronal enolase, NNE). The brain enolases represent the 1st example of functional markers for neuronal and glial cell types in brain. The 2 enzymes are structurally distinct with the evidence establishing that they are products of separate genes. Functionally, the neuronal enolase was to be uniquely stable to concentrations of chloride salts that rapidly inactivate the glial enzyme. NSE may represent an adaptation of this enzyme that is specifically suited to the neuronal milieu. A specific radioimmunoassay is described for NNE and NSE indicating that neuronal enzyme levels vary considerably when different brain areas are compared, suggesting a relationship between functional activity and levels of NSE. In addition to being a marker for neuronal cells, NSE is present in various glands. The cells of the APUD series (amine precursor uptake and decarboxylation cells) in the pituitary, adrenal medulla, pineal, thyroid and pancreas contain NSE. NSE is also a marker for these neuronlike endocrine cells since they are the only cells other than neurons that contain this protein.