Abstract

The uptake and binding of tritiated cortisol, corticosterone, and dexamethasone in cytosols isolated from various regions of non-adrenalectomized (intact) and adrenalectomized sheep brains and pituitaries were studied. [3H]-cortisol and [3H]-corticosterone were bound preferentially by cytosols from the hippocampal and septal regions of the brain, whereas, [3H]-dexamethasone was preferentially bound by cytosol from the pituitary. Cytosols isolated from the brains of adrenalectomized sheep bound significantly more [3H]-corticosterone than did cytosol from the brains of intact animals. Pre-incubation of cytosols from the hippocampus of adrenalectomized animals with non-radioactive testosterone or estradiol did not significantly block the subsequent binding of [3H]-cortisol. Results of pre-incubations with non-radioactive progesterone were non-reproducable with a large standard deviation among replicates. These findings provide evidence that the sites of feedback inhibition are the same in the sheep as described for other mammalian systems, and that in the sheep as in other mammals the principle site of localization of cortisol and corticosterone is in limbic structures of the brain, whereas, the principle site of uptake of dexamethasone is in the pituitary.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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