Selective increase of R-I subunit of cyclic AMP-dependent protein kinase in glia-rich primary cultures upon treatment with dibutyryl cyclic AMP.

Levels of cyclic GMP-dependent protein kinase and of the subunits (R-I, R-II and C) of cyclic AMP-dependent protein kinase were determined in two types of neural primary cell cultures that were either treated or not treated with dibutyryl cyclic AMP. Astroglia-rich cell cultures from newborn rat brain responded to exposure to dibutyryl cyclic AMP by a 2-3-fold increase in the level of R-I subunit, as demonstrated by two radioimmunological procedures, while the levels of the other subunits (R-II and C) and of cyclic GMP-dependent protein kinase remained unaffected. In contrast, neuron-rich cell cultures from embryonic rat brain did not display such a change in the level of R-I subunit. Thus, the elevation in the level of R-I elicited by dibutyryl cyclic AMP in normal non-malignant neural cells in culture was restricted to glial rather than neuronal cells.