Effect of melatonin on normal and sclerodermic skin fibroblast proliferation.
OBJECTIVE
We studied the effect of melatonin (MLT) (N-acetyl 5-methoxytryptamine) on the growth rate of normal skin fibroblasts and of fibroblasts from involved and apparently uninvolved skin of patients affected by systemic sclerosis (SSc).


METHODS
The growth rate was evaluated on the basis of growth curves and a 3H-thymidine incorporation assay.


RESULTS
Our results demonstrate that a dose of 200 micrograms/ml of MLT inhibits (> 80%) both control and SSc fibroblasts. Inhibition was dose-dependent and was greater than 70% for MLT concentrations of 100 micrograms/ml, 200 micrograms/ml and 400 micrograms/ml. 3H-thymidine incorporation was correlated with the effect on the growth curves (81% at 200 micrograms/ml of MLT). In contrast, at a low dosage of 6 micrograms/ml, MLT exerted a stimulatory effect on cell proliferation in all the cell lines analyzed. Cell viability was not affected by MLT at any of the concentrations tested. A recovery study indicated that replacement of MLT-containing medium with MLT-free medium resulted in a re-establishment of cell growth.


CONCLUSIONS
These results suggest that MLT, at higher dosages, is a potent inhibitor of the proliferation of fibroblasts derived from the skin of healthy and SSc patients.
Institute of Internal Medicine IV, University of Florence, Italy.
A M
AM
Carossino
A
A
Lombardi
M
M
Matucci-Cerinic
A
A
Pignone
M
M
Cagnoni
D002452:Cell Count / Q000187:drug effects; D018929:Cell Culture Techniques; D002455:Cell Division / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D008550:Melatonin / Q000494:pharmacology*; D012595:Scleroderma, Systemic; D012867:Skin / Q000166:cytology* / Q000187:drug effects; D013936:Thymidine / Q000378:metabolism
D008550:Melatonin; D013936:Thymidine