On the possible role of serotonin in the regulation of regeneration of cilia.

Abstract

A study was made of the interrelationship of serotonin, cyclic[c]AMP and Ca ions in the regulation of regeneration of cilia by Tetrahymena pyriformis. All these compounds stimulated the regeneration, whereas a blocker of serotonin synthesis, p-chlorophenylalanine and a Ca chelator, EGTA [ethylene glycolbis(.beta.-aminoethyl ether)N,N,N'',N''-tetraacetic acid], inhibited the process. This inhibition could be overcome by the addition of any of the stimulatory compounds. cAMP also was inhibitory at high concentrations. The intracellular concentration of this nucleotide increased during the regeneration, and this increase occurred precociously in the presence of serotonin. Serotonin may regulate ciliary regeneration by a mechanism involving cAMP and Ca ions, but the causal relationships among these compounds still need to be established.