Influence of melatonin on chick skeletal muscle cell growth

Melatonin as a highly lipophilic compound readily enters all subcellular compartments and acts by various mechanisms. In the present study, we investigated the effects of different concentrations of melatonin in medium (physiological and supraphysiological doses) at two treatment times (48 and 120 hr) on growth and changes of growth parameters of cultured chick embryonic skeletal muscle cells. The physiological doses of melatonin (100 pg to 10 ng/ml of medium) stimulated proliferation of cells and raised DNA, RNA protein contents and an incorporation of [3H]leucine into cell protein after 48 hr of treatment. The prolongation of exposure to melatonin in the physiological dose to 120 hr or an increase of melatonin dose to a supraphysiological one evoked the inhibition of cell growth and proliferation by decreasing the number of cells and the amount of labeled leucine incorporated into cell protein. Results demonstrate that melatonin's action in these cells is time and dose dependent.