Brain tissue oxidative damage as a possible mechanism for the deleterious effect of a chronic high dose of estradiol on learning and memory in ovariectomized rats Dano oxidativo ao tecido cerebral como possível mecanismo de efeito deletério da alta dose crônica de estradiol no aprendizado e memória de ratas ooforectomizadas

In addition to antioxidative effects, estrogens also exert pro-oxidative actions. The effect of chronic administration of a high dose of estradiol valerate on Morris water maze tasks and brain tissues oxidative damage was investigated. The Sham-Est and OVX-Est groups were treated with estradiol valerate (4 mg/kg) for 12 weeks. Escape latency and traveled path in the Sham-Est and OVX-Est groups were significantly higher than in the Sham and OVX groups (p<0.01 and p<0.001). In the probe trial, the animals of the Sham-Est and OVX-Est groups spent lower time in Q 1 compared to Sham and OVX groups (p<0.05 and p<0.001). In Sham-Est and OVX-Est groups, the brain tissue total thiol concentration was significantly lower, and malondialdehyde (MDA) concentrations were higher than in the Sham and OVX groups (p<0.05 and p<0.001). It is concluded that administration of high exogenous levels of estradiol impairs performance and enhances oxidative stress.