Interaction of prolactin, ANPergic, oxytocinergic and adrenal systems in response to extracellular volume expansion in rats

The present study evaluated the effect of acute extracellular volume expansion (EVE) induced by intravenous injection of isotonic (0.15 M NaCl) or hypertonic saline (0.3 M NaCl) on prolactin, corticosterone, vasopressin, oxytocin and atrial natriuretic peptide (ANP) secretion. Male Wistar rats were treated with bromocriptine, sulpiride or dexamethasone. After isotonic and hypertonic EVE, the control group showed a significant increase in the plasma concentrations of prolactin, corticosterone, ANP and oxytocin. The increase in ANP and oxytocin levels in response to hypertonic EVE was more pronounced than to isotonic EVE. Bromocriptine and sulpiride treatments did not modify corticosterone, ANP and oxytocin responses to either isotonic or hypertonic EVE. The increases in prolactin and oxytocin, but not ANP, were blocked in dexamethasone pretreated rats. In conclusion, isotonic or hypertonic EVE induced an increase in the plasma concentrations of prolactin, corticosterone, ANP and oxytocin. The increases in ANP and oxytocin were independent of plasma concentrations of prolactin. The increases in prolactin and oxytocin were blocked by the inhibition of the hypothalamo-pituitary-adrenal (HPA) axis by dexamethasone. However, dexamethasone did not alter the increase in ANP secretion induced by isotonic or hypertonic EVE. Therefore, prolactin might participate in regulation of the hydroelectrolytic balance in mammals; however, in the present study, there was no evidence for direct interaction with ANPergic and oxytocinergic systems. In addition, the responses of prolactin and oxytocin induced by isotonic or hypertonic EVE are modulated by the HPA axis.89554154

The expression of the ACTH receptor

Adrenal glucocorticoid secretion is regulated by adrenocorticotropic hormone (ACTH) acting through a specific cell membrane receptor (ACTH-R). The ACTH-R is a member of the G protein superfamily-coupled receptors and belongs to the subfamily of melanocortin receptors. The ACTH-R is mainly expressed in the adrenocortical cells showing a restricted tissue specificity, although ACTH is recognized by the other four melanocortin receptors. The cloning of the ACTH-R was followed by the study of this gene in human diseases such as familial glucocorticoid deficiency (FGD) and adrenocortical tumors. FGD is a rare autosomal recessive disease characterized by glucocorticoid deficiency, elevated plasma ACTH levels and preserved renin/aldosterone secretion. This disorder has been ascribed to an impaired adrenal responsiveness to ACTH due to a defective ACTH-R, a defect in intracellular signal transduction or an abnormality in adrenal cortical development. Mutations of the ACTH-R have been described in patients with FGD in segregation with the disease. The functional characterization of these mutations has been prevented by difficulties in expressing human ACTH-R in cells that lack endogenous melanocortin receptor activity. To overcome these difficulties we used Y6 cells, a mutant variant of the Y1 cell line, which possesses a non-expressed ACTH-R gene allowing the functional study without any background activity. Our results demonstrated that the several mutations of the ACTH-R found in FGD result in an impaired cAMP response or loss of sensitivity to ACTH stimulation. An ACTH-binding study showed an impairment of ligand binding with loss of the high affinity site in most of the mutations studied

Perceptions of human capital measures: from corporate executives and investors

Purpose This study compared the perceptions of executives and investors in terms of the importance to disclose human capital measures and their knowledge of those measures. Design/methodology/approach Forty-nine senior-level executives (41 % response rate) from service-oriented, public-listed companies in Australia and 33 investors (47% response rate) from various fund management companies responded to our survey. Findings The investors indicated the importance to disclose certain human capital measures more than the executives. The executives appeared to show a better understanding than the investors on indicators such as staff satisfaction index, staff capacity, motivational index, workforce stability, and workforce competence profile. Implications To date, researchers have explored human capital from a piecemeal perspective. A more integrated and multifaceted measure of human capital has the potential to benefit fund managers and executives. Disclosure of value added by employees, composition of staff (full-time, contract, or temporary), staff turnover, average years of experience, and average age of management and operational staff would shed some light on investment decisions for fund managers. Executives could utilize the measures to reflect on an assortment of human capital issues that are relevant to their organizations and stakeholders, especially the investment community. Originality/value This study proposed a more inclusive measure of human capital by integrating traditional measures of human capital and non-accounting measures (e.g., educational level, experience, and motivation). A comparison of the perspectives of executives and investors revealed preferences for certain information, which can help to improve the perception of transparency and accountability