Effect of Hormones on the Concentration of a Digoxin-like Material in Tetrahymena

The unicellular Tetrahymena pyriformis contains digoxin-like materials (digoxin, digitoxin, digoxigenin). The effect of two aminoacid-type hormones (histamine and serotonin) and a peptide hormone (insulin) was studied on the level of the hormone-like steroid, digoxin, in the concentrations of 10 and 10 by using immunocytochemistry and flow cytometric and confocal microscopic analysis. Each hormone elavated significantly the digoxin concentration at the end of the 30 min treatment. As Tetrahymena was maintained in a tryptone-yeast extract medium during the treatment, it seems to be likely that steroid synthesis was enhanced. The most effective was histamine, the effect of which was significantly more expressed than that of the others and the less effective (however significant), was serotonin. The results call attention to hormonal interactions inside the unicellular organism and on the possibility of mutual intercellular influences, considering the low effective hormone concentration which was needed for the striking effect.