Characterization of proliferation and differentiation of EGF-responsive striatal and septal precursor cells.

The epigenetic manipulation of precursors may provide data to elucidate the potential interactions among these cells in different brain regions. However, the response to epigenetic signals is modulated by the environment in which the cells are manipulated. Therefore, data regarding the action of a particular factor must be considered in the light of a specific system. To compare septal and striatal precursors, we have tested the effect of nerve growth factor (NGF) on the proliferation and neuronal differentiation of epidermal growth factor (EGF)-responsive cells from these brain regions. Precursors were cultivated as 'neuropheres' in serum free medium (SFM) to which NGF was added. NGF did not support the proliferation of EGF-generated precursors so that no differences in the cell magnitude with respect to control cultures were observed. Differentiation of precursors in SFM plus 1% fetal bovine serum (FBS) on poly-D-lysine showed that the neuron number was increased two-fold in septal cultures treated with NGF but not in those from striatum. A quantitative evaluation of the soma surface and the number of primary neurites showed differences between both populations of precursor-generated neurons. In addition, we also observed no influence of NGF on these parameters of cellular morphology. Thus, taken together these results seem to indicate that at this developmental stage in which these populations of precursors were isolated, heterogeneities exist between them, which is probably related to their origin and/or functional roles in vivo.