Dopamine toxicity contributes to melanocyte loss via melanocytorrhagy: an in vitro study

Catecholamines (epinephrine, norepinephrine, and dopamine) have been proposed as a possible cause of melanocyte loss. Dopamine has been observed to cause apoptosis in melanocytes via reactive oxygen species development, but the effect on melanocyte adhesion and proliferation still remains to be elucidated. Thus, we explored the dose- and time-dependent toxicity of catecholamines and the effect of dopamine on the proliferation and adhesion potential of melanocytes.

Primary culture of melanocytes was investigated in vitro for toxic effects of epinephrine, norepinephrine, and dopamine on metabolic activity via MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide) assay. Cells were observed microscopically for any phenotypic changes. Further cell proliferation, cell adhesion, and cell death pathway were explored under dopamine toxicity in dose- and time-dependent manner with RNase/PI method of cell cycle analysis, cell adhesion assay, and Annexin V-FITC/PI assay, respectively. Altered gene expressions were confirmed with a real-time polymerase chain reaction.

Metabolic activity of cells varied with time and different doses of epinephrine, norepinephrine, and dopamine. Dopamine was observed to be more toxic than epinephrine and norepinephrine. Melanocytes were observed to follow different cell death pathways at comparatively lower and higher concentrations of dopamine. Persistent exposure to dopamine resulted in decreased cell proliferation and adhesion potential with apoptotic changes. Gene expression changes also confirmed the weak adhesion and survival potential of cells under the toxic effects of dopamine.

Dopamine can alter melanocytes' adhesion and survival potential, leading to apoptotic cell death or melanocytorrhagic loss.