Baseline DNA damage levels in blood, liver and kidneys of adult sham-operated and gonadectomized rats

Many industrialized countries are facing demographic changes that manifest themselves in population aging. It is estimated that roughly one third of Europe’s population is 50+ with this share likely to increase. Therefore, the investigation of aging molecular mechanisms is a priority to facilitate healthy aging and improve the productivity/longevity of the aged population in both men and women. Within the frame of project Aging-related Expression of Membrane Transporters in Rats (AGEMETAR), aging is investigated in the Wistar rat model over 24 months, which corresponds to the elder age of humans. The aim of the current study was to investigate baseline DNA damage using the comet assay in kidneys, liver and blood mononuclear cells (BMCs) of adult 3-month-old rats of both sexes. In order to establish the influence of sex-hormones on baseline DNA damage, gonadectomized rats of both sexes were compared to sex-matched sham-operated animals (N=10/group). The sex-related differences of baseline DNA damage were not observed for any tissue studied in 3-month-old rats ; the percentage of comet DNA was in: BMCs 0.62±0.13% (male) compared to 0.63±0.20% (female) ; kidneys 1.00±0.24% (male) compared to 1.28±0.49% (female) ; and liver 0.86±0.21% (male) compared to 0.84±0.26% (female). Similarly, castration in males or ovariectomy in females had no effect on baseline DNA damage in: BMCs 0.55±0.13% (castration) and 0.53±0.14% (ovariectomy) ; kidneys 0.92±0.25% (castration) and 1.00±0.39% (ovariectomy) ; and liver 0.83±0.20% (castration) and 0.93±0.15% (ovariectomy) when compared to sex-matched sham-operated animals. Altogether, these results indicate that sex hormones have no effect on baseline DNA damage in the BMCs, kidneys and liver of 3-month-old rats. Furthermore, they provide useful information for further investigation of sex- and age-related differences of baseline DNA damage in the Wistar rat animal model of aging. (Supported by the Croatian Science Foundation Grant No. IP-2013-11-1481 ; AGEMETAR).