Effects of serotonin on strain L mouse cells in culture

Abstract

The growth of cultured mouse cells, strain L, in a strictly synthetic medium is depressed by serotonin. Beginning with concentrations of serotonin in the medium of 5 × 10 −4 M and higher, the mitotic burst which characterizes the logarithmic phase is quelled and at 3 × 10 −3 M serotonin completely eliminates growth. Under these conditions the utilization of glucose and the concomitant production of lactic acid are enhanced but the percent conversion of glucose to lactate is not altered. These alterations may arise as a secondary response to the depression of the rate of growth of L cells or, in part, from actions of serotonin on other areas of the metabolism of the cells. Incorporation studies with 14C-leucine indicate that serotonin does not act as a general protein synthesis inhibitor. Serotonin appears to differentially affect the transport of labelled nucleotide precursors into the cells and their metabolism once within. While the incorporation of 14C-uridine in both the acid-soluble and -insoluble fractions of the cells is slightly decreased, the incorporation of 3H-thymidine into the acid-soluble pool is greatly increased without a significant alteration in the incorporation into the acid-insoluble fraction. These alterations may be associated with changes in the specific activity of intracellular nucleotides.