Turkish Journal of Biology




This study aimed to investigate the effects of frequently changing photoperiods and alpha-lipoic acid treatment on melatonin, cortisol, oxidative markers, and some blood parameters. Eighty-four rats were randomly and equally divided into 7 groups: a control group, 3 prolonged light groups, and 3 prolonged dark groups. The study was completed in 2 stages, with 1- and 4-week periods, respectively. Blood samples were obtained at the end of the first and fourth weeks, and at the end of the dark period for the first and second stages. Serum aspartate aminotransferase and creatinine levels were significantly elevated in the prolonged dark olive oil group in the second stage. These values were similar to those of the control group in the prolonged dark water and alpha-lipoic acid groups. There was no statistically significant difference in total oxidant status between the prolonged dark olive oil group and the control group; however, the numerical total oxidant status value was increased. Higher urea and blood urea nitrogen levels were noted in the prolonged dark groups as compared with those in the prolonged light groups in the second stage. Melatonin and cortisol levels did not significantly change. The applied photoperiod changes in this study did not constitute a direct metabolic stressor for rats.


Photoperiod, melatonin, oxidative stress, alpha-lipoic acid

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