Adenosine 3',5'-monophosphate in highly purified and mixed primary cultures of neurons and non-neuronal cells from embryonic chick sympathetic ganglia

Primary cultures containing 99% neurons, 99% non-neuronal cell (glia), or both cell types prepared from the sympathetic ganglia of 12-day chick embryos. Levels of cyclic AMP in the non-neuronal cells (~ 14 pmoles per mg protein) were approximately three-fold higher than levels in the neurons (~ 4 pmoles per mg protein). Mixed cultures had concentrations of cyclic AMP which fell between the values measured for pure neuronal and pure non-neuronal cultures. The measured cyclic AMP values of mixed cultures were indistinguishable from values predicted by summing the expected contributions of the neurons and non-neuronal cells. Thus, contact between the neurons and non-neuronal cells in these mixed cultures did not appear to alter the level of cyclic AMP in either cell type. Neuronal-glial interactions, such as the specific neuronal stimulation of non-neuronal cell proliferation, occurred independently of any changes in the level of cyclic AMP in the mixed cultures. Cell density was varied in both pure and mixed cultures, and both cyclic AMP concentrations and amounts of 3H-thymidine incorporation into DNA were measured. The cyclic AMP content of the non-neuronal cells varied inversely with cell density. 3H-Thymidine incorporation was independed of cell density in both neuronal and non-neuronal cultures. Parallel density-dependent decreases in cyclic AMP concentration and 3H-thymidine incorporation were observed in mixed cultures as cell density was increased. The data suggest that there is no relationship between changes in rate of non-neuronal cell proliferation and cyclic AMP levels in these cultures. The effects of some putative neurotransmitters, analogs of transmitters, and adenosine on levels of cyclic AMP were determined in primary neuronal, non-neural, and mixed cultures of embryonic chick sympathetic ganglion cells. Adenosine increased the level of cyclic AMP in the non-neuronal cells but had no effect on levels in either neuronal or mixed cultures. Norepinephrine increased the level of cyclic AMP in neurons, had no effect on the non-neuronal levels, and decreased the cyclic nucleotide content of mixed cultures. Dopamine, isoproterenol, and pilocarpine all caused a reduction in the cyclic AMP content of mixed cultures but had no effect on levels of either neurons on non-neuronal cells. The measured cyclic AMP levels of norepinephrine- and isoproterenol-treated mixed cultures were significantly lower than the values predicted by summing the expected individual contributions of the neurons and the non-neuronal cells. Thus, cells in mixed cultures sometimes responded differently from cells in pure cultures.