Abstract:

Melatonin is an endogenous hormone, which regulates the light-dark cycle and is first shown to have antioxidant effects on 1993, is secreted from the pineal gland. One of the markers of oxidative stress in eythrocytes is the peroxidation of lipids in the membrane. The aim of this study is to investigate whether the erythrocyte membrane lipids are exposed to oxidative damage via circadian rhythm alterations. 90-120 days old, 200-250 gr, 50 male Swiss Albino rats, supplied from the University of Erciyes Experimental Clinical Research Centre, were used. The rats were exposed to 12/12 hours(h), 0/24h, 24/0h, 8/16h and 16/8h Light/Dark (L/D) cycle respectively, in special cages. After seperating the plasma, the erythrocytes were washed 3 times by phosphate buffer and malondialdehit (MDA) level which is an index of lipid peroxidation is measured spectrophotometrically in erythrocyt suspension. Furthermore, the plasma melatonin levels were evaluated by ELISA. Plasma melatonin levels were significantly higher in 0/24 h L/D (p<0.05) group whereas the levels decreased dramatically with the increase in exposure to light (p<0.05). MDA levels in group of 24/0 h L/D reduced, but the difference was not statistically significant. As a result, plasma melatonin levels due to circadian rhythm alterations caused lipid peroxidation in the erythrocyte membrane. However, these changes were not statistically different probably due to the number of the subject. For this reason, we suggested that circadian rhythm changes could affect MDA levels and oxidative damage in erythrocyte membrane

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