Adrenocortical Steroids and the Brain

摘要: In summary, a wide variety of effects adrenal steroids on the brain have been reported and recently exhaustively reviewed. From viewpoint endocrine physiology, however, what is often forgotten extraordinary difference in signal level between two unique products cortex, mineralocorticoid glucocorticoid hormones. Levels cortisol or corticosterone are 2-3 orders magnitude higher than those aldosterone, that tempered by perhaps one order much binding glucocorticoids to plasma protein. The signal-detecting mechanisms for lower-intensity signal, i.e. receptor, must therefore powerful specificity-conferring enable it recognize, bind, respond aldosterone. vitro studies from number laboratories shown Type I receptors, both classic target tissues (kidney, parotid, gut) nontarget (pituitary, hippocampus), cannot distinguish aldosterone corticosterone. This finding highlights problem aldosterone-selectivity kidney (Na+ transport) appetite). vivo studies, contrast, show very poorly taken up and/or retained kidney, colon, pituitary (but not hippocampus) mature 10-day-old (minimal transcortin) rats, whereas well all tissues, evidence tissue-specific selectivity vivo. Two nonexclusive (i.e. possibly additive) models such proposed, "prebinding" other "postbinding". Both accommodate experimental findings nonselectivity cytosol preparations stringent specificity seen receptor effector studies. any real sense, action still largely an area unconnected phenomenology, despite efforts talented individuals groups over past decades. Without descriptions phenomena, even most basic ablation replacement type, we no chance making physiological statements. It equally important, attempt make coherent erect scaffolding hypothesis can be tested against existing serve suggest further logical sequence. These hypotheses themselves, used reify them, may validated, altered, rejected next few years.(ABSTRACT TRUNCATED AT 400 WORDS)