We examined the influence of melatonin, serotonin and tryptophan on the basal and δ-aminolevulinic acid (ALA)-induced porphyrin content in HaCaT, SKMel-23 and HepG2 cells. ALA-preincubated and ALA-free cells were fed with medium containing 1 mM melatonin, serotonin or tryptophan. After 24 h the porphyrin content in the cells and in the culture medium was measured. In the three cell lines the inbucation with 1 mM ALA over 24 h increased the porphyrin concentration in all cell lines in different degrees: HepG2 > SKMel-23 > HaCaT cells. In HepG2 cells, neither melatonin, serotonin nor tryptophan influenced ALA-induced porphyrin concentrations significantly, but all three indoles depressed the porphyrin levels in SKMel-23 and HaCaT cells. The indoles may decrease the ALA uptake in HaCaT or SKMel-23 cells. Another mechanism could be the inhibition of enzymes converting ALA into porphyrins.

Keywords:
Melatonin, Serotonin, Tryptophan, δ-Aminolevulinic acid, Porphyrin metabolism
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© 1997 S. Karger AG, Basel
1997
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