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Corticosteroid Regulation of Gene Expression and Binding Characteristics of Vasopressin Receptors in the Rat Brain
Author(s) -
Patchev Vladimir K.,
Almeida Osborne F. X.
Publication year - 1995
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1995.tb01153.x
Subject(s) - vasopressin , endocrinology , medicine , receptor , corticosterone , hippocampus , glucocorticoid receptor , adrenalectomy , biology , arc (geometry) , in situ hybridization , gene expression , glucocorticoid , arginine vasopressin receptor 1b , vasopressin receptor , gene , hormone , antagonist , biochemistry , geometry , mathematics
Arginine‐vasopressin (AVP) plays significant roles in neuroendocrine and autonomic regulation, and in processing of cognitive information. Its synthesis and secretion are subject to control by circulating glucocorticoids. The lateral septum and subdivisions of the hippocampus are innervated by AVP‐ergic fibres and, together with AVP‐producing neurons in the hypothalamic paraventricular nucleus, are major neural targets of glucocorticoid negative feedback. In this study, we investigated the effects of chronic adrenalectomy (ADX) and subsequent treatment with supraphysiological doses of corticosterone (B) on the gene expression of AVP receptors of the V 1a subtype in the septum, hippocampus and hypothalamic arcuate (ARC) nucleus using semiquantitative in situ hybridization histochemistry. Adrenalectomy did not alter AVP receptor expression in any of the structures studied. Supplementation with B significantly decreased AVP receptor expression in the lateral septum and hippocampus, whereas receptor mRNA levels in the ARC were indistinguishable from those measured in controls. In a complementary study, we investigated the binding characteristics of V 1 AVP receptors in membrane preparations from the hippocampus. Adrenalectomy significantly decreased the number of AVP binding sites, and chronic corticosteroid treatment was associated with a further suppression of AVP receptor concentrations in this structure. These results indicate that the gene transcription of V 1a AVP receptors in the brain is regulated by circulating glucocorticoids in a site‐specific fashion that largely reflects the corticosteroid sensitivity of the corresponding structure. The comparison between corticosteroid‐induced changes in receptor binding and gene transcription in the hippocampus suggests that two separate mechanisms may be operational in the regulation of AVP receptors by glucocorticoids: increased AVP release probably accounts for the observed down‐regulation in receptor binding following ADX, whereas increased corticosteroid levels interfere with AVP receptor expression.