Uptake and binding of [3H]hydrocortisone by various pig brain regions.

The cytosol fraction of septum, hypothalamus, and hippocampus of intact and adrenalectomized pigs possessed greater concentrations of radioactivity than the cytosol fraction of amygdala, pituitary, and cortex after an intraventricular injection of [1,2-3H]hydrocortisone. Nuclear extracts from the same brain regions possessed higher concentrations of radioactivity than nuclear extracts of the other brain regions of intact pigs. Nuclear extracts of amygdala, pituitary and hypothalamus from adrenalectomized pigs exhibited the greatest increase over intact pigs in labeled hormone concentration. When adrenalectomized pigs were administered dexamethasone prior to [3H]hydrocortisone, uptake of label was most depressed in hippocampal cytosol and cuclear extract. Also sensitive to the competitive effects of dexamethasone were septal and pituitary nuclear extracts. In intact pigs, pituitary, hippocampus and cortex exhibited higher ratios of bound to total hormone in the cytososl fraction than the other brain regions. Hippocampal and amygdala cytosol possessed the greater magnitude of increase in the ratio of bound to total hormone in adrenalectomized versus intact pigs. The pituitary, septum, amygdala, and cortex of intact and adrenalectomized pigs possessed a ratio of bound to total hormone in nuclear extract 5-10 times greater than that in hippocampus and hypothalamus. However, the latter two regions exhibited a greater increase in bound: total hormone after administration of labeled hormone to adrenalectomized pigs than nuclear extracts of the other brain regions.