The investigation of photoperiod varitions and alpha lipoic acid application effects on oxidative indicators, melatonin and cortisol hormons and some blood parameters in rats.

SUMMARYIn this study, we aimed to investigate oxidative markers, melatonin and cortisollevels and some blood parameters to study the effects of alternating 2-daybiorhythm-type photoperiods. Additionally, we also monitored the effect of alphalipoic acid, an updated and effective antioxidant, on this process.Eighty-four male Sprague-Dawley rats, weighing 250-300gr, are enrolled inthe study. Rats are divided in 7 equal groups, which are labeled as follows; group 1:control group which underwent 12/12 Light/Dark (L/D) cycle. Group 2: prolongedlight olive oil group (DOG), which was fed with 2cc/kg/day olive oil via oral gavagein 2-day periods of 16/8 L/D and 12/12 L/D. Group 3: prolonged dark olive oilgroup (NOG), which was fed with 2cc/kg/day olive oil via oral gavage in periods of8/16 L/D and 12/12 L/D. Group 4: prolonged light water group (DWG), which wasfed with 2cc/kg/day water via oral gavage in periods of 16/8 L/D and 12/12 L/D.Group 5: prolonged dark water group (NWG), which was fed with 2cc/kg/day watervia oral gavage in periods of 8/16 L/D and 12/12 L/D. Group 6: prolonged lightlipoic acid group (DLG), which was fed with ?-lipoic acid 100mg/kg/day dissolvedin 2cc olive oil via oral gavage in periods of 16/8 L/D and 12/12 L/D. Group 7:prolonged dark lipoic acid group (NLG), which was fed with ?-lipoic acid100mg/kg/day dissolved in 2cc olive oil via oral gavage in periods of 8/16 L/D and12/12 L/D. Study is completed in two stages, which are subsequently composed ofone-week and four-week periods, respectively. Blood samples are obtained underanesthesia at the end of the first and fourth weeks and the dark period for the first andsecond stages, respectively. Leukocyte in whole blood, serum aspartateaminotransferase (AST), alanine aminotransferase (ALT), urea, blood urea nitrogen(BUN), creatinine, cortisol, melatonin, total antioxidant capacity (TAC), totalantioxidant level (TOC) parameters were determined.There was significant elevation in AST and creatinine levels of theprolonged-dark olive oil group in the second stage of the study. These values weresimilar to control group in NWG and NLG groups, the other two prolonged-darkgroups. There was no statistically significant difference between this group and thecontrol group; however, numerical TOC value was increased. Increased levels ofurea and BUN were noted in prolonged-dark groups in the second stage with respectto prolonged light groups. In the second stage, leukocyte counts were increased inDWG and DLG. There was no statistically significant difference in leukocyte countsof all groups, except DWG and DLG, in comparison with the control group;however, a numerical increase is identified. Melatonin and cortisol values did notchange significantly.In conclusion; two-day periods of 16/8 L/D and 8/16 L/D photoperiods do notcause measurable acute or chronic stress in subjects. Administration of olive oil inprolonged dark periods, in which animals are active, may increase oxidative stressproducts. The increase in oxidant capacity may increase AST values, lipoic acid maybe effective in suppressing this increase and may stabilize oxidant markers in controlgroup levels. As the active period of animals is prolonged, the amino-acidcatabolism may increase in order to contribute to glyconeogenesis, the process ofglucose synthesis from non-carbohydrate resources, and therefore increase the ureaand BUN values in groups of prolonged dark periods with respect to prolonged lightperiods. Results suggest that alternating photoperiod rhythms do not increasemeasurable metabolic stress in rats; however, since applications like gavage is astressor in animals and may cause increase in leukocytes.Key words: AST, Alfa Lipoic acid, Leukocyt, Oxidatif Stress, Photoperiod.