Corticosteroid Regulation of Gene Expression and Binding Characteristics of Vasopressin Receptors in the Rat Brain

Abstract

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 V1a 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 V1 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 V1a 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of estrogen receptor α and β in the mouse central nervous system: In vivo autoradiographic and immunocytochemical analyses

“…Consistent with this hypothesis, an estrogen response element (ERE) sequence, as well as an alternate site for estrogen regulation, an AP‐1 site, have been reported within the regulatory region of the rat AVP gene (Gainer et al, 1993; Grace et al, 1999). Moreover, previous studies showed that estrogen upregulates AVP gene expression in the PVN (Patchev and Almeida, 1995) and increases circulating levels of AVP (Skowsky et al, 1979). More recently, Shapiro et al (2000) demonstrated a direct regulation of the AVP gene promoter by ERβ using a luciferase reporter assay.…”

Diurnal rhythms of behavior and brain mRNA expression for arginine vasotocin, isotocin, and their receptors in wild Amargosa pupfish (Cyprinodon nevadensis amargosae)

“…Clearly, future studies are needed to explore the role of this V1a2 receptor in behavior and reproduction, and these studies should include experiments designed to test for influences of sex steroids on VT receptor gene transcription in the piscine brain. It is important to note, however, that V1a receptor binding in the mammalian brain has also been demonstrated to be regulated by glucocorticoids (Patchev and Almeida 1995;Watters et al 1996), and diurnal differences in brain V1a2 mRNA levels between the sexes could alternatively be explained by sex differences in social stresses (e.g., aggression). VT has been shown to stimulate pituitary ACTH release in fish (Baker et al 1996), and acute stressor exposure alters pro-VT mRNA levels in the hypothalamus in trout (Gilchriest et al 2000).…”

Vasopressin increases [Ca2+]i in differentiated astrocytes by activation of V1b/V3 receptors but has no effect in mature cortical neurons

“…Neurons in the supraoptic nucleus and circumventricular organs express AVP receptors (Hurbin et al, 1998;Gouzenes et al, 1999;Washburn et al, 1999), probably mainly of the V1a subtype. V1 AVP receptors have also consistently been demonstrated on neurons in hippocampus (Brinton et al, 1994;Patchev and Almeida, 1995;Mihara et al, 1999) and amygdala (Lu et al, 1997). In some hippocampal neurons the AVP-induced increase in [Ca 2ϩ ] i depends upon extracellular Ca 2ϩ , identifying the receptors as being of the V1a subtype (Mihara et al, 1999), whereas other neurons in hippocampus may be of the V1b/V3 subtype (Vaccari et al, 1998;Omura et al, 1999).…”