Behavioural effect of adrenalectomy: reversal by glucocorticoids or [D-Ala2,Met5]enkephalinamide.
Rats adrenalectomized 4-6 d before a 15-min swimming test showed levels of immobility indistinguishable from controls. Retested 24 h later, adrenalectomized rats showed significantly reduced (28%) immobility compared with controls (70%) or hypophysectomized rats (60%), but not hypophysectomized-adrenalectomized rats (41%). The effect of adrenalectomy was reversed by the administration (within 1 h of initial test, but not subsequently) of dexamethasone (6-20 micrograms; 65% immobility) and corticosterone (6 mg; 74%), but not by the mineralocorticoid deoxycorticosterone (6 mg; 33%). [D-Ala2,Met5]enkephalinamide (5-50 micrograms) also restored immobility (66%). We postulate that hormones from both adrenal medulla and cortex are involved in the retention of information post-stress, and that these hormones act directly on the CNS rather than via the pituitary, since the response to adrenalectomy is not dependent on the presence of the pituitary gland.
D000315:Adrenalectomy; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology*; D007016:Hypophysectomy; D007103:Immobilization; D007858:Learning / Q000187:drug effects*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013550:Swimming
D005938:Glucocorticoids; D004744:Enkephalin, Methionine; C022118:enkephalinamide-Met, Ala(2)-; D003907:Dexamethasone