Effect of estrogen on nucleotide excision repair of N2a neuroblastoma cells

Until now reduced estrogen level has been considered to affect some psychiatric symptoms, because there are sex differences in onset of Schizophrenia and Alzheimer's disease. Estrogen is associated with cognitive functions, and it has been reported to protect oxidative damage of DNA related to base excision repair (BER). Some patients with Xeroderma Pigmentosum, who have normal BER and impaired nucleotide excision repair (NER), are known to be suffering from mental retardation. Therefore we hypothesized that impaired NER was partly associated with pathology of mental disorder and investigated the effects of estrogen on NER for ultraviolet-induced DNA damage. The N2a neuroblastoma cell line was used as a representative of neuronal cells and 17β-estradiol was selected as one of the most active estrogen derivatives. There were no significant effects of 17β-estradiol on prevention of DNA damage, promotion of DNA repair, or cell survival at the concentration of 0-0.1 μM 17β-estradiol (below cytotoxicity level). These results described that estrogen might not directly affect NER except through another DNA repair system.