Endothelin Adrenocortical Secretagogue Effect Is Mediated by the B Receptor in Rats

Abstract

We investigated the gene expression and localization of endothelin-1 (ET-1) receptor subtypes ET(A) and ET(B) in the rat adrenal cortex as well as their involvement in the corticosteroid secretagogue effect of ET-1 in vitro. Reverse transcription-polymerase chain reaction with primers specific for ET(A) and ET(B) cDNAs demonstrated the expression of both receptor genes in homogenates of adrenocortical tissue. However, in isolated zona glomerulosa and zona fasciculata cells, only ET(B) mRNA was detected. Autoradiographic examination of the selective displacement of 125I-ET-1 binding by BQ-123 and BQ-788 (specific ligands for ET(A) and ET(B), respectively) indicated that zona glomerulosa possesses both ET(A) and ET(B), whereas zona fasciculata is exclusively provided with ET(B). ET-1 enhanced in a concentration-dependent manner aldosterone and corticosterone secretions of dispersed zona glomerulosa and zona fasciculata cells, respectively. The ET(B) antagonist BQ-788 markedly reduced the secretory response of zona glomerulosa cells and completely suppressed that of zona fasciculata cells, whereas the ET(A) antagonist BQ-123 was ineffective. These findings indicate that in the rat, the adrenocortical secretagogue action of ET-1 is mediated by the ET(B) receptor subtype and that the ET(A) receptor is not directly involved in such an effect.

Early life stress downregulates endothelin receptor expression and enhances acute stress-mediated blood pressure responses in adult rats

“…It has been shown that ET-1 stimulates plasma corticosterone levels associated with a stress response (35) and that stimulation of the ET B receptor mediates the release of corticosterone from the adrenal cortex (2,46). Our data show that Fig.…”

“…Reports have linked ET-1 and attenuation of sympathetically mediated responses; specifically, our laboratory has shown that ET A receptor activation attenuates the acute stress-induced pressor response (10). In addition, both ET receptor subtypes have been implicated in triggering the release of corticosterone (2,46). Some rodent models display acute stress-mediated corticosterone release; thus, alterations in the expression or function of the ET pathway may be involved in the regulation of shortand/or long-term stress responses.…”

Role of the Endogenous Adrenomedullin System in Regulating the Secretion and Growth of Rat Adrenal Cortex

“…ZG was separated from inner zones by gently stripping the gland capsule, and dispersed ZG and ZF/R cells were obtained by sequential collagenase digestion and mechanical disaggregation (17). Dispersed cells were suspended in DMEM containing 100 U/ml penicillin and 100 µg/ml streptomycin, and 0.6 µg/ml ODNs in ETR vehicle, and plated in 35-mm tissue culture dishes.…”

Galanin enhances corticosterone secretion from dispersed rat adrenocortical cells through the activation of GAL-R1 and GAL-R2 receptors coupled to the adenylate cyclase-dependent signaling cascade

“…It, therefore, seemed worthwhile to investigate by reverse transcription (RT)-polymerase chain reaction (PCR) the expression of galanin receptor mRNA in adrenocortical cells, and to address the subtype(s) of receptor involved in the glucocorticoid-secretagogue action of galanin by the selective immuno-blockade of GAL-R1, GAL-R2 or GAL-R3. (24,25). Some mixed zona glomerulosa/ inner cell preparations were also prepared.…”