Beta-estradiol reduces lipid peroxidation and depth of injury in cold-induced brain injury model.

Estrogen has neuroprotective effects in neurodegenerative disorders and models of neuronal damage. The effectiveness of estradiol (EST) (1 mg/kg and 10 mg/kg doses) in cold-induced brain injury (CIB) model was evaluated and compared with standard dexamethasone treatment. Forty-eight male Wistar rats (250-300 g) were randomly divided into 6 groups: sham operated, CIB + no treatment, CIB + 1 mg/kg dexamethasone, CIB + 1 mg/kg EST, CIB + 10 mg/kg EST, CIB + vehicle (ethanol). Rats were placed on stereotaxic frame and a craniotomy of 5 mm diameter was performed on the parietal lob under general anesthesia (ketamine+xylazine). A metal probe of 5 mm diameter was cooled (2 min) in liquid nitrogen (-190 degrees C) and was applied on the craniotomy area for 3 min. The treatment was started immediately after the CIB. Twenty-four hours later the whole brain was isolated and study parameters were assessed. The parameters were tissue wet/dry weight ratio, lipid peroxidation, and histopathological examination of the depth of injury. Both 1 mg/kg dexamethasone and 1mg/kg EST treatment significantly reduced all the measured injury parameters, whereas 10 mg/kg EST had no effect on any of the parameters. This study shows that EST at lower concentrations is beneficial in this model of cold-induced brain injury. However, the effect of EST is dual and higher concentrations, in contrast, do not affect or even may be detrimental in brain injury.