Iron-induced oxidative DNA damage in rat sperm cells in vivo and in vitro

Abstract

We investigated whether acute iron intoxication causes oxidative DNA damage, measured in terms of 7-hydro-8-oxo-2′-deoxyguanosine, 8-oxodG, in nuclear DNA in testes and epididymal sperm cells in vivo and in vitro in rats. In addition, we investigated levels of the modified nucleoside in liver and kidney and measured its urinary excretion.

Sperm cells were isolated from the epididymides and the testes cells were isolated after homogenisation. In vitro, the sperm and testes cells were incubated with increasing concentrations of FeCl₂ ranging from 0 to 600 μM. The median (range) levels of 8-oxodG/10⁵ dG in the epididymal sperm cells increased from 0.48 (0.42–0.90) to 15.1 (11.4–17.6) (p < 0.05), whereas the level rose from 0.63 (0.22–0.81) to 8.8 (4.5–11.6) (p < 0.05) at 0 and 600 μM, respectively, in the testicular cells.

In vivo groups of 7–8 rats received 0, 200 or 400 mg iron/kg as dextran i.p. After 24h, epididymal sperm cells, testes, kidneys and liver were collected for analysis. Kidney and sperm DNA showed a significant increase in 8-oxodG in the iron-treated animals. The median (range) values of the 8-oxodG/10⁵ dG in the epididymal sperm cells rose from 0.66 (0.38–1.09) to 1.12 (0.84–5.88) (p < 0.05) at 0 and 400 mg iron/kg, respectively, whereas the values in the testes and liver showed no significant change. In the kidneys the 8-oxodG/10⁵ dG median (range) values were 0.98 (0.73–1.24), 1.21 (1.13–1.69) and 1.34 (1.12–1.66) after 0, 200 and 400 mg iron/kg, respectively (p < 0.05).

The 8-oxodG-excretion rate was measured in 24 h urine before and after iron treatment. The rate of urinary 8-oxodG excretion increased from 129 (104–179) pmol/24 h before treatment to 147 (110–239) pmol/24h after treatment in the group receiving 400 mg iron/kg (p < 0.05).

The results indicate that acute iron intoxication may increase oxidative damage to sperm and kidney DNA.

Keywords:

• Iron dextran
• epididymal sperm cells
• oxidative DNA damage
• 7-hydro-8-oxo-2′-deoxyguanosine