Somatostatin in the hippocampus mediates dexamethasone-induced suppression of corticosterone secretion in the rat.
We evaluated the effect of different manipulations of central somatostatin (SS) neurons on dexamethasone (Dex) induced suppression of the hypophyseal-pituitary axis. The Dex suppression test was performed in male rats by evaluating the reduction of plasma levels of corticosterone occurring 4 h after administration of Dex. Administration of cysteamine, a depletor of SS stores, or passive immunization by intracerebroventricular administration of a saturating dose of anti-SS gamma-globulins completely suppressed the ability of Dex to reduce plasma corticosterone levels. Additionally, anti-SS gamma-globulins, infused under stereotaxic control into two discrete areas of the hippocampus (CA3 and DG), completely blocked Dex-induced inhibition of corticosterone secretion. These data indicate that hippocampal SS neurons play a role in the negative feedback regulation of glucocorticoid secretion.
Department of Pharmacology, Chemotherapy, and Toxicology, University of Milan, Italy.
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Ferrara
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Cocchi
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Müller
D000818:Animals; D003345:Corticosterone / Q000378:metabolism*; D003543:Cysteamine / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D005246:Feedback; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007116:Immunization, Passive; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011921:Rats, Inbred WKY; D013004:Somatostatin / Q000276:immunology / Q000502:physiology*
D013004:Somatostatin; D003543:Cysteamine; D003907:Dexamethasone; D003345:Corticosterone