Oxidative damage of nuclear DNA in liver of rats exposed to psychological stress.

Male Sprague-Dawley rats were exposed to conditioned emotional stimuli in a communication box, which is much more psychologically conditioned stress than the commonly used restraint and water immersion, to investigate the induction of oxidative DNA damage by psychological stress. Significantly higher levels of 8-hydroxy-2'-deoxyguanosine in rat liver nuclear DNA than in the controls [1.46 +/- 0.19 (SD) 8-hydroxy-2'-deoxyguanosine/10(5) deoxyguanosine] were detected immediately after the second (1.90 +/- 0.27, P < 0.01), third (3.10 +/- 0.94, P < 0.01), and fourth exposure (2.95 +/- 1.17, P < 0.01) to conditioned emotional stimuli. This is the first evidence that oxidative damage to nuclear DNA is induced by psychological stress.