Opposite regulation by glucocorticoids of the alpha(1B)- and alpha(2A)-adrenoreceptor mRNA levels in rat cultured anterior hypothalamic slices

In this study we investigated whether the expression of alpha(1B)- and alph a(2A)-adrenoreceptor mRNAs is differently modulated by glucocorticoids in r at cultured anterior hypothalamus slices. Using a semi-quantitative reverse transcription-polymerase chain reaction assay, the level of the als-adreno receptor mRNA was significantly reduced in slices cultured in steroid free- medium when compared with that measured in standard medium (i.e. containing basal adrenosteroid plasma concentrations). In contrast, the expression of the alpha(2A)-adrenoreceptor mRNA was markedly increased. Finally, the rat io of alpha(1B)- versus alpha(2A)-mRNA levels was about 1.7 and 0.7 in stan dard and steroid-free medium, respectively. These responses were completely reversed by supplementation with corticosterone. These findings provide th e first evidence that in vitro glucocorticoids may regulate, in an opposite manner, the expression of the alpha(1B)-and alpha(2A)-adrenoreceptor mRNAs in the hypothalamus. This kind of regulation could be related to steroid-d ependent changes in the noradrenergic control of neuroendocrine secretions, (C) 1999 Elsevier Science Ireland Ltd, All rights reserved.