On the role of serotonin and 5-methoxy-tryptamine in the regulation of cell division in sea urchin eggs

The presence of serotonin in sea urchin eggs has been ascertained by high-performance liquid chromatography and thin-layer chromatography analysis of tissue-free bioamines. The results show the presence of both serotonin and 5-methoxytryptamine. The role of these substances in the cell division process has been studied by using the serotonin antagonists, gramine and metergoline. Both antagonists cause a significant delay of the cell division which, however, can be prevented by the addition of either 5-hydroxytryptophane, serotonin, or 5-methoxytryptamine. The effect of gramine on the different stages of the cell division process has also been investigated. Neither S phase nor mitosis are affected by the serotonin antagonist, while cleavage is delayed. The effect of serotonin seems mediated by calcium ions and cAMP. Gramine causes a marked increase in radio-calcium efflux from the fertilized egg, and at the same time lowers the cAMP level.