Uticaj utreniranosti i polimorfizama u genima za glukokortikoidni, mineralokortikoidni i adrenokortikotropni receptor na fiziološku adaptaciju hipotalamo-hipofizno-nadbubrežne osovine na hronično ponavljani fizički stres

Abstract

Svaka forma stresa ima višestruke efekte na ceo organizam, ali reakcije i adaptacije različitih organskih sistema zavise od mnogih faktora, a prvenstveno od samog tipa stresa. Trening profesionalnih sportista predstavlja specifičnu formu stresa koji je dobrovoljan, intermitentan i kontrolisan, ali visokog intenziteta i kontinuirano ponavljan tokom dugog vremenskog perioda. Adaptacije na ovu formu stresa još uvek nisu u potpunosti definisane. Kao deo neuroendokrinih odgovora na stress, hipotalamo-hipofizno-nadbubrežna (HHN) osovina se aktivira tokom vežbanja, sa porastom nivoa kortizola kao krajnjim efektom ove aktivacije. Hronična hiperkortizolemija ima mnoge štetne efekte, ali porast nivoa kortizola tokom akutnog stresa je od izuzetnog značaja za metaboličke adaptacije, modulaciju imunskog sistema, kardiovaskularni odgovor i remodelovanje mišića. Ipak, ponavljani stress, bilo akutni ili hronični, modulira osetljivost HHN osovine, dovodeći do smanjenog odgovora na akutnu stimulaciju. Ovakva alostatka adaptacija je predložena i kod sportista. Međutim načini adaptacije još uvek nisu jasni, kao i nivo na kome se adaptacija dešava: smanjenjem osetljivosti nadbubrega na stimulaciju od strane adrenokortikotropnog hormona (ACTH), i/ili možda smanjenjem osetljivosti HHN osovine na negativnu povratnu spregu. Takođe, do sada nije ispitivano na koji način polimorfizmi gena za receptore hormona HHN osovine utiču način odgovora na akutni fizički stress. Ciljevi: Ispitivali smo specifičnosti adaptacije HHN osovine kod profesionalnih sportista, izloženih ponavljanom, dugotrajnom fizičkom stresu. Ispitivali smo postojanje faznog pomeranja normalnog cirkadijalnog ritma sekrecije kortizola i ACTH. Ispitivali smo diferencijalni odgovor HHN osovine na akutni fizički stres u zavisnosti od utreniranosti i postojanja polimorfizama u genima za glukokortikoidni (GR), mineralokortikoidni (MR) i ACTH receptor. Takođe, ispitivali smo osetljivost negativne povratne sprege HHN osovine. Materijal i metode: Studijsku grupu je činilo 3 grupe sportista (ukupno 55): 1) 21 vaterpolista, 2) 15 rvača, 3) 19 odbojkaša. Svi sportisti su se takmičili na najvišem nacionalnoj nivou, i ispitivani su u periodu priprema za takmičenje...

Any form of stress exerts profound effects on entire organism, but reactions and adaptations of different organ systems depend on many factors, notably a type of stress itself. Physical training of professional athletes comprises specific form of stress that is voluntary, intermittent and controllable, but of high intensity and repeated continuously over a long period of time. Adaptations to this form of stress are still under a lot of debate. Being a feature of neuroendocrine responses to stress, hypothalamic-pituitary-adrenal (HPA) axis is activated during exercise, with cortisol elevation as an endpoint of this activation. Chronic hypercortisolism has many deleterious effects, but cortisol rise during acute stress is of utmost importance for metabolic adaptations, immune system modulation, cardiovascular responses and muscle tissue remodeling. However, repeated stress, either acute or chronic, modulates the HPA axis sensitivity, leading to a reduced response to acute stimulation. This allostatic adaptation has also been proposed in athletes. Modes of this adaptation are still unclear, as well as the exact level of adaptation: decreased adrenal sensitivity to adrenocorticotropic hormone (ACTH) stimulation, and/or decreased HPA axis sensitivity to cortisol negative feedback. Likewise, so far it has not been investigated in which was specific polymorphisms in genes for receptors of hormones of HPA axis influence mode of response to acute physical stress. Objective: We investigated specificities of HPA axis adaptation in professional athletes, exposed to repeated, long term physical stress. We analyzed presence of phase shift in normal circadian rhythm of secretion of cortisol and ACTH. We investigated differential HPA axis response to acute physical stress depending on level of training, and presence of polymorphisms in genes for glucocorticoid (GR), mineralocorticoid (MR) and ACTH receptor. Also, we analyzed sensitivity of HPA axis negative feedback. Materials and methods: Study group consisted from 3 groups of professional athletes. (altogether 55): 1) 21 waterpolo player, 2) 15 wrestlers, 3) 19 volley ball players. All athletes competed at highest national level, and were tested during pre-competition season...