The in vitro binding of estradiol by the guinea pig cerebral cortex

The in vitro dynamics of the binding of estradiol by the cerebral cortex of the female guinea pig were studied. The uptake of ³H-estradiol by slices of cerebral cortex was temperature-dependent, being highest at 37°C. A significant increment in the binding of ³H-estradiol was observed in the cytosol up to 240 minutes. The increase on the binding of ³H-estradiol by the cytosol and the nucleus of the brain followed a linear relationship with the increment in protein concentration. The cytosol protein(s) of the cerebral cortex that bind(s) estradiol contain sulphydril groups and are thermolabiles. The number of binding sites and the Ka for estradiol in the cytosol of the cerebral cortex were 30 fm/mg proteins and 1.33 × 10⁹ M^?1, respectively. These results could suggest that in the guinea pig cerebral cortex there are receptors for estradiol, similar to those described in the uterus.