Multihormonal control of proliferation and cytosolic glycerol phosphate dehydrogenase, lactate dehydrogenase and malic enzyme in glial cells in culture

Abstract

We have examined the effect of a physiological concentration of l-triiodothyronine on the activity of cytosolic enzymes in the C6 rat glioma cell line. l-Triiodothyronine decreased glycerol phosphate dehydrogenase activity. This effect seems to be rather specific, since l-triiodothyronine did not change malic enzyme or lactate dehydrogenase activity and did not alter the amount of either cytosolic or total cell protein. Dexamethasone greatly increased glycerol phosphate dehydrogenase and l-triiodothyronine also decreased the response to the glucocorticoid. Noradrenaline or dibutyryl cyclic AMP potentiated the dexamethasone-induced specific activity of this enzyme, and l-triiodothyronine lowered the response to the combined effects of these agents. The effect of l-triiodothyronine is not restricted to the C6 cells, since it also decreased basal glycerol phosphate dehydrogenase activity in primary cultures of cells dissociated from brains of embryonic mice. The results indicate that thyroid hormones have a direct effect on the modulation of cytosolic glycerol phosphate dehydrogenase in cultured cells of glial origin. © 1986.