Dexamethasone and adrenalectomy alter brain (Na+,K+)-ATPase responses to noradrenergic stimulation or depletion.
We investigated the effects of adrenalectomy or dexamethasone treatment on the regulation of brain (Na+,K+)-ATPase by noradrenaline. Noradrenergic stimulation was produced by repeated injections of yohimbine, and noradrenaline depletion by an injection of the selective toxin DSP4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine). Adrenalectomy had no effect on the number of ouabain binding sites in cerebral cortex, but increased the number of sites synergistically with noradrenergic stimulation. Dexamethasone prevented the decrease in ouabain binding in rats treated with DSP4, but did not itself alter ouabain binding. Neither dexamethasone nor adrenalectomy altered the changes in beta-receptor binding associated with the noradrenergic manipulations. Changes in exposure to corticosteroids may alter the coupling between adrenoceptor binding and second messenger activation in a way that affects (Na+,K+)-ATPase regulation.
Swann
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AC
Department of Psychiatry, University of Texas Medical School, Houston 77225.
D000311:Adrenal Glands / Q000502:physiology*; D000315:Adrenalectomy; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D010042:Ouabain / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D010042:Ouabain; D003907:Dexamethasone; D000254:Sodium-Potassium-Exchanging ATPase; D009638:Norepinephrine