Decrease in number of somatostatin receptors in rat brain after adrenalectomy: normalization after glucocorticoid replacement.

The effects of adrenalectomy on somatostatin (SS) concentration and specific binding in cerebral cortex, hippocampus, striatum, and hypothalamus were examined using [125I-Tyr11]SS as the binding ligand. Adrenalectomy did not affect the concentration of SS-like immunoreactivity in the brain areas studied. Nevertheless, the number of SS receptors was significantly decreased in membrane preparations from hippocampus, striatum, and hypothalamus, but not in cerebral cortex. No significant differences in the apparent binding affinity values were seen after adrenalectomy. The adrenalectomy-induced decreases in [125I-Tyr11]SS receptors were completely reversed by glucocorticoid replacement with dexamethasone. These results demonstrate that adrenalectomy modulates SS receptors in discrete brain areas, suggesting the existence of a possible relationship between corticosteroids and SS in the neuronal activity of these structures. The physiological significance of these findings remains to be clarified.