[P2-165] Circadian Rhythms of Oxidative Stress Markers and Melatonin Metabolite in Patients with Xeroderma Pigmentosum Group A.
[Introduction] Xeroerma pigmentosum group A (XPA) is a genetic disorder in DNA nucleotide excision repair (NER) with severe neurological disorders. It is suggested that oxidative stress and disturbed melatonin metabolism may be involved in XPA patients. Herein we confirmed the diurnal variation of melatonin metabolites, oxidative stress markers and antioxidant power in urine of patients with XPA and age-matched controls. [Methodology] We measured 6-sulfatoxymelatonin (6-SM) which is metabolite of melatonin, 8-hydroxy-2’-deoxyguanosine (8-OHdG) which is a marker of oxidative DNA damage, hexanoyl-lysine (HEL) which is a marker of lipid peroxidation, and total antioxidant power (TAO), using enzyme-linked immunosorbent assay (ELISA). [Results] The peak of 6-SM was seen at 6:00 in both the XPA patients and controls, though the peak value is lower specifically in the younger age group of XPA patients. The older XPA patients demonstrated an increase in the urinary levels of 8-OHdG and HEL, having a robust peak at 6:00 and 18:00, respectively. In addition, the urinary level of TAO was decreased in the older XPA patients. [Conclusions] It is speculated that oxidative stress and antioxidant properties may have a diurnal variation, and the circadian rhythm is likely to influence the NER itself. We believe that the administration of melatonin has the possibility to ameliorate the augmented oxidative stress in neurodegeneration especially in the older XPA patients, modulating the melatonin metabolism and the circadian rhythm.