Induction of lactate dehydrogenase by dibutyryl cAMP in primary cultures of central nervous tissue is an oligodendroglial marker

Abstract

In vitro induction of lactate dehydrogenase ( l-lactate:NAD +-oxidoreductase, EC 1.1.1.27, LDH) in response to catecholamines occurs in neural cell lines expressing glial properties 2–4. LDH is a tetrameric protein, consisting of two types of subunits: M-type or LDH-5 (predominant in skeletal muscle), and H-type or LDH-1 (predominant in heart muscle). These subunits are encoded by two nonallelic genes 1,18,14. Several studies have shown that LDH is induced by catecholamines via a cAMP-mediated process 2,3. We have previously shown that the mechanism of catecholamine induction for LDH in C6 glial cells involves an increase in the differential rates of synthesis of the two LDH subunits, suggesting that the regulation occurs at both genetic loci 6. Recently, a method has become available to prepare separate cultures of oligodendrocytes and astrocytes from newborn cerebral tissue 10. Both of these cultures markedly increase their intracellular cAMP concentration following a challenge by β-adrenergic agonists 10. We have now investigated the regulation of LDH activity by dibutyryl cAMP (Bt 2cAMP) in separate cultures of neurons, oligodendrocytes and astrocytes. The induction involving an increase in the rate of synthesis by Bt 2cAMP is solely characteristic of oligodendrocytes. Moreover, both LDH genes contribute to this regulation.