Cyclic-amp dependent protein kinase in mouse striatal neurones and astrocytes in primary culture: development, subcellular distribution and stimulation of endogenous phosphorylation.

The cAMP-dependent protein kinase (cAMPdPK) activity and the endogenous cAMP-dependent phosphorylation of protein have been studied on pure populations of striatal neurones or astrocytes in primary culture originating from embryonic mouse brain. The appearance of cAMPdPK in cultured striatal neurones was rapid and paralleled neuritic outgrowth and cell maturation. Its highest value, reached between day 6 and 9 in culture, was comparable to that found in adult tissue. In cultured neurones as in adult striatum, cAMPdPK was found both in membrane and in cytoplasmic fractions. In astrocytes, cAMPdPK activity was low and only detectable in the cytoplasm. The presence of several cAMP-regulated phosphoproteins could be demonstrated in cultured cells, some of which being neurone-specific or astrocyte-specific. The phosphorylation of these striatal proteins was either enhanced, or, surprisingly, inhibited in the presence of cAMP. This study indicates that primary cultures of nerve cells provide valuable preparations for analysing protein phosphorylation processes induced by neurotransmitters.