Two simian virus 40 (SV40)-transformed cell lines from the mouse striatum and mesencephalon presenting astrocytic characters. II. Interactions with mesencephalic neurons.

In an accompanying paper we report the characterization on the basis of pharmacological and immunological criteria of two astrocytic cell lines originating from the rostral mesencephalon and the striatum of the embryonic mouse (F7-Mes and F12-Str). This report compares the interactions of primary mesencephalic neurons with the astrocytic clones to that displayed with either an SV40-transformed fibroblastic clone (BT2) or primary mesencephalic (G-Mes) and striatal (G-Str) astrocytes. We show that BT2 differs from all other cell types (F7-Mes, F12-Str, G-Mes and G-Str). Indeed, as opposed to these cells BT2 is a poor substratum for neuronal adhesion or neuritic growth. This was clearly demonstrated by morphological examination of cocultures of the tested cells with either mesencephalic explants or dissociated cells. In addition a statistical analysis is provided which only concerns the dopaminergic (DA) neurons visualized by autoradiography after specific uptake of [3H]DA. The number of DA cells attached, the total length of their neurites and the degree of branching behaviour were examined. With the help of these criteria we show that F7-Mes and F12-Str are very similar to primary astrocytes and differ highly significantly from BT2. However, although sharing the main astrocytic features, F7-Mes and F12-Str do not differ from one another in their ability to induce the branching of DA neurites as their non-transformed counterparts do.