The Influence of Melatonin Supplementation in the Group of Persons Performing Competitive Sport.

The research aims to determine the impact of 30-day supplementation of melatonin on the antioxidative defense mechanisms and the release of markers of oxidative stress and inflammation in rowers and footballers undergoing training of submaximal intensity.

Athlete's body, by its high oxygen demand and increased aerobic metabolism, is exposed to the formation and oxidizing action of reactive oxygen species (ROS). Imbalance between the mechanisms of ROS generation and antioxidative defense of the body can lead to oxidative stress expressed by elevated concentrations of lipid peroxidation products, such as malondialdehyde, isoprostanes (8-iso-PGF2α), oxidized low-density lipoprotein molecules (ox-LDL). The body's defense against ROS includes two systems: nonenzymatic and enzymatic. Small-molecule antioxidants include reduced glutathione (GSH). Due to the presence of -SH groups, glutathione has strong reductive properties. The compound is a substrate for glutathione peroxidase (GSH-Px) which decomposes hydrogen peroxide and organic peroxides. Among antioxidant enzymes are also: superoxide dismutase (Cu-Zn-SOD, scavenges superoxide anion radical), catalase (CAT, reduces hydrogen peroxide), and glutathione reductase (GR, reduces oxidized glutathione). Another well-known small-molecule antioxidant is melatonin, hormone of the pineal gland. It has been demonstrated that this compound can reduce hydrogen peroxide, scavenge hydroxyl radical and deactivate nitric oxide radical. Another manifestation of disruption of homeostasis in the body of a professional athlete are enhanced inflammatory processes. This can be explained by the fact that during physical effort of varied intensity, increased activity of myeloperoxidase and higher levels of mRNA for tumor necrosis factor, interleukin-1 and -6 are observed. Interleukin-6, also known as myokine, is a particularly important marker of intense physical effort released from damaged muscles. Myokine is also the main upregulator of the synthesis of C-reactive protein (CRP) in the liver, hence measuring the concentration of the protein can indicate the intensity of inflammatory processes in an athlete's body. It has been demonstrated that melatonin, in addition to its hormonal and antioxidant properties, can modulate inflammatory processes by reducing the synthesis of proinflammatory cytokines. Taking into account the multidirectional function of melatonin, it seems interesting to establish the impact of 30-day supplementation of this hormone on the antioxidative defense mechanisms and the release of markers of oxidative stress and inflammation in rowers and footballers undergoing training of submaximal intensity.

Melatonin, Glutathione, Glutathione peroxidase, Malondialdehyde, Isoprostanes, anti-ox-LDL, Superoxide dismutase, Glutathione reductase, Interleukin-6, C-reactive protein, Autonomic nervous system

Measurement of oxidative stress parameters and inflammatory markers concentration before melatonin administration, at baseline.

The study was conducted in football players and rowers and the control group. Samples of blood from the basilic vein were taken once, from both the control group and the athletes at baseline. In blood serum, the ELISA method was used to determine the concentrations of melatonin, isoprostanes (8-iso-PGF2α), anti-ox-LDL antibodies, interleukin-6 and C-reactive protein (CRP). In red blood cells, the concentration of reduced glutathione (GSH), thiobarbituric acid reactive substances (malondialdehyde, MDA) were determined and the activity of glutathione peroxidase (GSH-Px), cytoplasmic superoxide dismutase (SOD-1) and glutathione reductase (GR) were determined.

Changes in oxidative stress parameters and inflammatory markers concentration afer 30 days of melatonin administration in athletes.

After 30 days of melatonin supplementation, samples of blood from the basilic vein were taken only from athletes, once, in the same day. In biochemistry laboratory, in blood serum, the ELISA method was used to determine the concentrations of melatonin, isoprostanes (8-iso-PGF2α), anti-ox-LDL antibodies, interleukin-6 and C-reactive protein (CRP). In red blood cells, the concentration of reduced glutathione (GSH), thiobarbituric acid reactive substances (malondialdehyde, MDA) were determined and the activity of glutathione peroxidase (GSH-Px), cytoplasmic superoxide dismutase (SOD-1) and glutathione reductase (GR) were determined.

Inclusion Criteria: sign informed consent form for participation in the study Exclusion Criteria: diseases the participants will not be minor and incapacitated persons, soldiers, prisoners and persons dependent in any way from the investigators

Department of Positron Emission Tomography and Molcecular Diagnostics, Collegium Medicum of Nicolaus Copernicus University