SCHWANN-CELL RESPONSES TO FORSKOLIN AND CYCLIC-AMP ANALOGS - COMPARATIVE-STUDY OF MOUSE AND RAT SCHWANN-CELLS

Forskolin and cAMP analogues (8-bromo cAMP and dibutyryl cAMP) induced proliferation or surface galC expression, depending on the concentrations, in rat and mouse Schwann cells in vitro. However, rat Schwann cells required much higher concentrations of these agents than mouse Schwann cells in both proliferation and surface galC expression. The concentrations needed for cellular proliferation were 0.5 mu M forskolin or 10 mu M cAMP analogues in mice and 2.5 mu M forskolin or 50 mu M cAMP analogues in rats. Surface galC was expressed in mouse Schwann cells at concentrations of 10 mu M forskolin or 100 mu M cAMP analogues, while in rat Schwann cells, 50 mu M forskolin or 500 mu M cAMP analogues was needed for expression of surface galC. Rat Schwann cells transformed from an elongated spindle shape to flattened cells by the addition of these agents. However, mouse Schwann cells remained spindle shaped and their processes were apparently elongated at concentrations of more than 1.0 mu M forskolin or 100 mu M cAMP analogues. These results may reflect the differences in the cellular metabolism between mouse and rat cells. Moreover, the elongation of mouse Schwann cell processes appeared to be associated with surface galC expression, suggesting that elongation may be an initial signal for differentiation in mouse Schwann cells.