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Ergogenic response of melatonin ar nadir and acrophase of spontaneous activity and its consequences on IKK/NF-kB pathway activity and muscle tissue damage

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Author(s):
Wladimir Rafael Beck
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Educação Física
Defense date:
Examining board members:
Claudio Alexandre Gobatto; Eduardo Rochete Ropelle; Marco Túlio de Mello; Gustavo Gomes de Araújo; Taisa Belli
Advisor: Claudio Alexandre Gobatto
Abstract

Mainly produced by mammal¿s pineal gland, melatonin is an indoleamine classically related to circadian rhythm synchronizing, primarily through geophysical light dark cycle. Many recently identified properties of melatonin has stimulated many studies about it effect on exercised organism. Optimize the use of energy substrates during exercise, inhibit exacerbated inflammation and decrease tissue damage are well documented effects. Among others, these melatonin properties has been considered as potentially ergogenic out, what comprises a controversial issue in the current sports scientific literature. The aim of this thesis was to determine the ergogenic capacity of melatonin in exhaustive exercise at maximal aerobic capacity intensity (tlim) at nadir and acrophase of spontaneous physical activity (SPA), identifying the effects of such condition on the oxidative skeletal muscle IKK/NF-'capa'B activity, metabolic, hematologic and tissue damage in swimming rats. Thus, two procedures were originally standardized: i) apparatus manufacture and mathematical calculations routine for determining the circadian rhythm of SPA in rats, and ii) the incremental test (IT) for estimative of the intensity corresponding to the maximal aerobic capacity of swimming rats. Animals were kept at light/dark cycle of 12 hours with bright lights on at 06:00h (560nm; 60lux). SPA were recorded throughout day, being nadir and acrophase of such variable corresponding to 12:00 (ZT 6) and 20:00h (ZT 14), respectively. Male Wistar albino rats were randomly splitted to incremental test (IT) performing, which begun at specifics time of day (SPA nadir or acrophase) at 90 days-old. To acrophase swimming testing were employed special illumination to avoid influences of light on physiological melatonin secretion (>600nm; <15lux). At 92 days-old a solution with or with no exogenous melatonin (10 mg.kg-1, I.P.) were administered to rats that were or not submitted to tlim 30 minutes after. Euthanasia was conducted one hour after tlim to biological material withdraw. Laboratory techniques of Western Blotting and ELISA were employed, and commercial kits and biochemical techniques. Melatonin significantly increases the tolerance to the proposed exercise, however, post hoc assumptions showed significant differences only between animals that assessments begun at SPA acrophase, when endogenous melatonin is usually higher in nocturnal rats. Significantly higher inflammatory and tissue damage markers were found to exercised animals assessed at wakefulness period (higher SA) that received exogenous melatonin, where were also found higher tlim. Thus, the massive ergogenic effect of melatonin leads to higher periods of muscle contraction, which superimposed melatonin protective effect on the tissue damage and its anti-inflammatory action. The proposed exercise resembles cyclic long duration sports, as marathons. However, direct inferences between models should be carefully conducted once the Human Being presents wakefulness period during daily hours, when melatonin is found at lower concentrations, so, the interpretation of melatonin action may differ between species. (AU)

FAPESP's process: 11/13226-1 - Ergogenic response of melatonin during the nadir and acrophase of spontaneous activity: consequences on IKK/Nf-kB via
Grantee:Wladimir Rafael Beck
Support type: Scholarships in Brazil - Doctorate