Effects of melanin and manganese on dna damage and repair in PC12-derived neurons

• Published in: Free radical biology & medicine Vol. 36; no. 9; pp. 1144 - 1154
• Main Authors: Sava, Vasyl, Mosquera, Diana, Song, Shijie, Cardozo-Pelaez, Fernando, Sánchez-Ramos, Juan R
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2004
• Subjects: 8-Oxoguanine DNA glycosylase; Animals; Cell Survival - drug effects; DNA - analysis; DNA - chemistry; DNA Damage; DNA damage and repair; DNA Glycosylases - antagonists & inhibitors; DNA Glycosylases - metabolism; DNA Repair - drug effects; Free radicals; Guanine - analogs & derivatives; Guanine - analysis; Guanine - chemistry; Lipid Peroxidation - drug effects; Manganese - pharmacology; Melanins - metabolism; Melanins - toxicity; Neuronal degeneration; Neurons - drug effects; Neurons - metabolism; PC12 Cells; Rats; Superoxide Dismutase - metabolism; Thiobarbituric Acid Reactive Substances - analysis; Neuronal degeneration; DNA damage and repair; Free radicals; 8-Oxoguanine DNA glycosylase
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2004.01.019

The mechanism of neurotoxicity produced by the interaction of melanin with manganese was investigated in PC12-derived neuronal cell cultures. The cells were incubated with melanin (25–500 μg/ml), MnCl 2 (10 ng/ml–100 μg/ml) and a combination of both substances for 24 and 72 h. Incubation with either toxicant alone resulted in a minimal decrease in cell viability. The combination of melanin and manganese caused significant (up to 60%) decreases in viability of PC12 cells in a dose-dependent manner. Increases in oxidative DNA damage, indicated by levels of 8-hydroxy-2′deoxyguanosine (8-oxodG), was associated with decreased cell viability. Melanin alone, but not manganese alone, resulted in increased oxidative DNA damage. The maximal increase in 8-oxodG caused by melanin was about seven times higher than control after 24 h of exposure. The activity of the DNA repair enzyme, 8-oxoguanine DNA glycosylase (OGG1), was increased in cells incubated with single toxicants and their combinations for 24 h. On the third day of incubation with the toxicants, activity of OGG1 declined below control levels and cell viability significantly decreased. Melanin was observed to have an inhibitory effect on OGG1 activity. Study of the regulation of OGG1 activity in response to melanin and manganese may provide insights into the vulnerability of nigral neurons to oxidative stress in Parkinson's disease.