Evaluation of DNA damage in the lymphocytes of young, elderly and Alzheimer's disease patients treated with β-estradiol in the comet assay

Abstract

Background: The antioxidant activity of estrogen has a beneficial impact in Alzheimer's disease. A variety of clinical studies have demonstrated that estrogen replacement therapy in postmenopausal women results in a lower frequency of AD, delaying the onset of the neurodegenerative cascade. On the other hand, it has been demonstrated that estrogens may exhibit genotoxic effects, especially at elevated tissue concentrations. Therefore, the aim of this study was to determine whether β-estradiol induces DNA damage in the peripheral blood lymphocytes of healthy young females and males, healthy elderly females and males and females and males with Alzheimer's disease. Methods: All experiments were performed using the alkaline version of the Comet assay (single cell gel electrophoresis), on six donors per each experimental group and controls. Results: In the Comet assay, a significant increase of DNA migration was observed in the lymphocytes of all treated groups (young and elderly females, young and elderly males, AD females and AD males) at all β-estradiol concentrations (50 µmol/L, 100 µmol/L and 250 µmol/L) used in this investigation. In all the experiments cell viability was over 80%.Conclusions: Lymphocytes are sensitive to the test concentrations of β-estradiol in the Comet assay regardless of gender, age and health condition of the examined subjects. Therefore, the role of β-estradiol in cellular DNA damage has been confirmed.

Uvod: Antioksidativna svojstva estrogena imaju povoljan uticaj na Alchajmerovu bolest (AB). Brojne kliničke studije su pokazale da primena hormonske supstitucione terapije estrogenom kod žena u postmenopauzi smanjuje učestalost pojave AB, odlažući početak neurodegenerativnih procesa. S druge strane, pokazano je da estrogeni mogu ispoljiti genotoksičan efekat, naročito pri povišenim koncentracijama u tkivu. Shodno tome, cilj ove studije bio je ispitivanje sposobnosti β-estradiola da izazove oštećenja u limfocitima periferne krvi zdravih mladih žena i muškaraca, zdravih starih žena i muškaraca, kao i žena i muškaraca koji boluju od Alchajmerove bolesti. Metode: Svi eksperimenti su izvedeni primenom alkalne verzije komet testa (gel-elektroforeza DNK pojedinačnih ćelija), na po šest subjekata u svakoj ispitivanoj grupi. Rezultati: Upotrebom komet testa, zabeleženo je značajno povećanje migracije DNK u limfocitima ispitanika iz svih tretiranih grupa (mladih i starih žena, mladih i starih muškaraca kao i kod žena i muškaraca sa AB), pri svim koncentracijama β-estradiola (50 µmol/L, 100 µmol/L i 250 µmol/L) koje su korišćene u ovoj studiji. U svim eksperimentima vijabilnost ćelija je bila iznad 80%. Zaključak: Limfociti periferne krvi osetljivi su na testirane koncentracije β-estradiola, bez obzira na pol, godište i zdravstveno stanje ispitanika. U skladu s navedenim nalazima, potvrđena je uloga β-estradiola u izazivanju oštećenja na ćelijskoj DNK.