Vasculoprotective effect of cilostazol in aldosterone-induced hypertensive rats.

Cilostazol (CILO), a selective inhibitor of phosphodiesterase 3 with potent antithrombotic property, has been shown to have a vasculoprotective effect in atherosclerosis animal models due to its potential anti-inflammatory and antioxidant actions. This study was undertaken to investigate whether CILO has in fact any vasculoprotective effects in aldosterone-induced hypertensive rats (Aldo-rats), and whether CILO affects Aldo-induced oxidative stress, nitric oxide (NO) production and pro-inflammatory gene expression. Treatment with CILO markedly ameliorated perivascular inflammatory changes in the coronary arterioles of Aldo-rats without affecting the systolic blood pressure and left ventricular weight. Treatment with CILO also prevented the increase in plasma levels of thiobarbituric acid-reactive substances, an oxidative stress marker, as well as decreased urinary NOx excretion in Aldo-rats. Furthermore, CILO almost completely inhibited a set of upregulated proinflammatory genes (ICAM-1, MCP-1, PDGF-A, osteopontin, MMP-2 and ACE), as well as NAD(P)H oxidase components (p22phox, gp91phox, p47phox) and Aldo-inducible genes (SGK-1 and NHE-1) in the aortic tissues from Aldo-rats. Taken together, this study showed for the first time that CILO prevented Aldo-induced vascular inflammation and injury without affecting the blood pressure, suggesting its vasculoprotective effect on Aldo-induced vascular injury independent of blood pressure.

Diagnostic accuracy of adrenal venous sampling in comparison with other parameters in primary aldosteronism.

This retrospective study was aimed 1) to compare the difference of the findings between adrenal CT scan and adrenal venous sampling (AVS) in 35 cases with definite primary aldosteronism (PA) for assessment of the diagnostic efficacy of PA subgroup (unilateral and bilateral adrenal hypersecretion: UAH and BAH), and 2) to determine the clinical and biochemical parameters as potential predictors for PA subgroup. There were significant discordant results based on AVS and CT scan in subgrouping PA; 9 of 17 BAH patients (53%) had unilateral lesion on CT scan, while 4 of 18 UAH patients (22%) had no apparent or bilateral lesions on CT scan. Among three diagnostic criteria, absolute values of plasma aldosterone concentration (PAC) in both adrenal veins, lateralized and contralateral ratios of aldosterone/cortisol after ACTH stimulation during AVS to determine the laterality, none of them showed 100% diagnostic accuracy if applied alone. Among several clinical and biochemical parameters, hypokalemia (<3.4 mEq/l), younger age (<52 y) and poor response of PAC (<1.45) after furosemide-upright posture, proved to be significant predictors for UAH, with higher specificities (100%, 88%, 94%, respectively). Therefore, despite AVS as a gold standard method to determine the laterality of aldosterone hypersecretion in PA, our study shows that no single criterion could provide definite diagnostic value for its laterality by AVS. It is also suggested that most PA patients, if not all, with a distinct unilateral adrenal lesion on CT accompanied by hypokalemia, younger age and poor aldosterone response to renin stimulation, could undergo adrenalectomy without prior AVS.

Aldosterone induces superoxide generation via Rac1 activation in endothelial cells.

Currently, aldosterone is believed to be involved in the development of cardiovascular injury as a potential cardiovascular risk hormone. However, its exact cellular mechanisms remain obscure. This study was undertaken to examine the effect of aldosterone on superoxide production in cultured rat aortic endothelial cells with possible involvement of the small GTP-binding (G) protein Rac1. The aldosterone levels showed a time-dependent (6-24 h) and dose-dependent (10(-8) to 10(-6) m) increase in superoxide generation, whose effect was abolished by mineralocorticoid receptor antagonist (eplerenone), Src inhibitor (PP2), and reduced nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase inhibitor (apocynin). Aldosterone activated NADP(H) oxidase and Rac1, whose effects were abolished by eplerenone. The aldosterone-induced superoxide generation was abolished either by nonselective small G protein inhibitor (Clostridium difficile toxin A) or dominant-negative Rac1. Dominant-negative Rac1 also inhibited aldosterone-induced ACE gene expression. Thus, the present study is the first to demonstrate that aldosterone induces superoxide generation via mineralocorticoid receptor-mediated activation of NAD(P)H-oxidase and Rac1 in endothelial cells, thereby contributing to the development of aldosterone-induced vascular injury.

Angiotensin II receptor type 1-mediated vascular oxidative stress and proinflammatory gene expression in aldosterone-induced hypertension: the possible role of local renin-angiotensin system.

Recently, aldosterone has been shown to activate local renin-angiotensin system in vitro. To elucidate the potential role of local renin-angiotensin system in aldosterone-induced cardiovascular injury, we investigated the effects of selective mineralocorticoid receptor (MR) antagonist eplerenone (EPL), angiotensin (Ang) II type 1 receptor antagonist candesartan (ARB), and superoxide dismutase mimetic tempol (TEM) on the development of hypertension, vascular injury, oxidative stress, and inflammatory-related gene expression in aldosterone-treated hypertensive rats. The increased systolic blood pressure and vascular inflammatory changes were attenuated by cotreatment either with EPL, ARB, or TEM. Aldosterone increased angiotensin-converting enzyme expression in the aortic tissue; its effects were blocked by EPL but not by ARB or TEM. Aldosterone also increased Ang II contents in the aortic tissue in the presence of low circulating Ang II concentrations. Aldosterone induced expression of various inflammatory-related genes, whose effects were abolished by EPL, whereas the inhibitory effects of ARB and TEM varied depending on the gene. Aldosterone caused greater accumulation of the oxidant stress marker 4-hydroxy-2-neonenal in the endothelium; its effect was abolished by EPL, ARB, or TEM. Aldosterone increased mRNA levels of reduced nicotinamide adenine dinucleotide phosphate oxidase components; their effect was abolished by EPL, whereas ARB and TEM decreased only the p47phox mRNA level but not that of p22phox or gp91phox. The present findings suggest that the Ang II-dependent pathway resulting from vascular angiotensin-converting enzyme up-regulation and Ang II-independent pathway are both involved in the underlying mechanisms resulting in the development of hypertension, vascular inflammation, and oxidative stress induced by aldosterone.

Systemic distribution of salusin expression in the rat.

Salusin-alpha and salusin-beta are multifunctional bioactive peptides with hypotensive and bradycardic effects. They were originally identified from full-length human cDNAs by bioinformatics analyses. Salusin peptides are expressed in human tissues at the mRNA level, but no information is available about their systemic distributions in any species. We examined the distributions of preprosalusin mRNA and the salusin peptides in a variety of normal rat organs. Whereas preprosalusin mRNA was expressed ubiquitously, immunoreactive salusin-beta was detected most strongly in the hypothalamus and posterior pituitary, and less abundantly in the anterior pituitary and gastrointestinal, immune, and hematopoietic systems. Salusin-beta-positive cells appeared to be of either hematopoietic or endocrine origin, and many hematopoietic cells were also stained with anti-CD68, which specifically recognizes macrophages. Salusin-alpha-like immunoreactivity was not detected in any of the rat tissues. These results indicate that rat salusin is immunologically similar to human salusin-beta and widely expressed, especially in the immune, gastrointestinal, and central nervous systems and mainly in endocrine- and hematopoietic-derived cells.

Angiotensin II induces monocyte chemoattractant protein-1 expression via a nuclear factor-kappaB-dependent pathway in rat preadipocytes.

Both monocyte chemoattractant protein-1 (MCP-1), a member of chemokine family, and angiotensinogen, a precursor of angiotensin (ANG) II, are produced by adipose tissue and increased in obese state. MCP-1 has been shown to decrease insulin-stimulated glucose uptake and several adipogenic genes expression in adipocytes in vitro, suggesting its pathophysiological significance in obesity. However, the pathophysiological interaction between MCP-1 and ANG II in adipose tissue remains unknown. The present study was undertaken to investigate the potential mechanisms by which ANG II affects MCP-1 gene expression in rat primary cultured preadipocytes and adipose tissue in vivo. ANG II significantly increased steady-state MCP-1 mRNA levels in a time- and dose-dependent manner. The ANG II-induced MCP-1 mRNA and protein expression was completely abolished by ANG II type 1 (AT1)-receptor antagonist (valsartan). An antioxidant/NF-kappaB inhibitor (pyrrolidine dithiocarbamate) and an inhibitor of 1kappaB-alpha phosphorylation (Bay 11-7085) also blocked ANG II-induced MCP-1 mRNA expression. ANG II induced translocation of NF-kappaB p65 subunit from cytoplasm to nucleus by immunocytochemical study. Luciferase assay using reporter constructs containing MCP-1 promoter region revealed that two NF-kappaB binding sites in its enhancer region were essential for the ANG II-induced promoter activities. Furthermore, basal mRNA and protein of MCP-1 during preadipocyte differentiation were significantly greater in preadipocytes than in differentiated adipocytes, whose effect was more pronounced in the presence of ANG II. Exogenous administration of ANG II to rats led to increased MCP-1 expression in epididymal, subcutaneous, and mesenteric adipose tissue. In conclusion, our present study demonstrates that ANG II increases MCP-1 gene expression via ANG II type 1 receptor-mediated and NF-kappaB-dependent pathway in rat preadipocytes as well as adipose MCP-1 expression in vivo. Thus the augmented MCP-1 expression by ANG II in preadipocytes may provide a new link between obesity and cardiovascular disease.

A case of estrogen-secreting adrenocortical carcinoma with subclinical Cushing's syndrome.

A 25-year-old man was found to have a large right adrenal mass detected by abdominal echography and computed tomography, and presented with a mild gynecomastia. Endocrine study showed increased serum concentrations and urinary excretion of estrogens and dehydroepiandorosterone sulfate (DHEA-S). The patient had no Cushingoid features but autonomous cortisol secretion, compatible with the diagnosis of subclinical Cushing's syndrome. Surgical removal of the adrenal tumor led to normalization of serum and urinary excretion of estrogens and DHEA-S. Histopathological examination revealed a high-grade adrenocortical carcinoma (ACC). The disorganized expression of all the steroidogenic enzymes in individual tumor cells was demonstrated by immunohistochemical analysis, and the abundant expression of both aromatase mRNA and insulin-like growth factor (IGF)-II mRNA was shown by RT-PCR. These data suggest the excessive secretion of estrogen as well as the ineffective steroidogenesis by the adrenal tumor. This is a very rare case of estrogen-secreting ACC associated with subclinical Cushing's syndrome.

Aldosterone increases osteopontin gene expression in rat endothelial cells.

Aldosterone is currently recognized as one of the important risk hormones for cardiovascular disease. However, the cellular mechanism by which aldosterone affects the process of cardiovascular injury has not been well understood. In the present study, we investigated whether aldosterone induces pro-inflammatory genes expression in rat aortic endothelial cells. Aldosterone significantly increased steady-state osteopontin mRNA and protein levels, but not those of adhesion molecules or chemokine. The stimulatory effect of aldosterone on osteopontin expression was time-dependent (3-24h) and dose-dependent (10(-10)-10(-6)M), and abolished by a mineralocorticoid receptor (MR) antagonist spironolactone, but not by a glucocorticoid receptor antagonist RU486. The aldosterone-induced osteopontin mRNA expression was completely blocked by a transcription inhibitor, actinomycin D, and a protein synthesis inhibitor, cycloheximide. Thus, the present study demonstrated for the first time that aldosterone directly acts on endothelial cells to induce osteopontin gene expression via MR-mediated genomic action, which may be responsible for the initiation of inflammation and fibrosis in cardiovascular tissue induced by aldosterone.

A case with primary aldosteronism due to unilateral multiple adrenocortical micronodules.

A 46-year-old male with long-term treatment-resistant hypertension and past history of cerebral hemorrhage was found to have suppressed plasma renin activity (PRA) and normal plasma aldosterone concentration (PAC) with aldosterone/renin ratio of 25.3. Furosemide plus upright test did not stimulate PRA, but computed tomography scan of the abdomen revealed no abnormal lesions in either adrenal gland. Selective adrenal venous sampling (SAVS) showed that PAC in the left and the right adrenal vein were 1000 ng/dl and 230 ng/dl, respectively, which increased to 1500 ng/dl and 620 ng/dl, respectively, after ACTH stimulation. Diagnosis of primary aldosteronism due to hypersecretion of aldosterone from the left adrenal gland was made, and laparoscopic left adrenalectomy was performed. Pathological examination of the 'apparently normal' adrenal tissue resected revealed the presence of poorly encapsulated multiple adrenocortical micronodules which showed positive immunoreactivity for 3beta-hydroxysteroid dehydrogenase by immunohistochemical study, but negative immunoreactivity in the hyperplastic zona glomerulosa consistent with paradoxical hyperplasia associated with primary aldosteronism. Postoperatively, PRA was normalized and his high blood pressure was well controlled with lower doses of antihypertensive drugs than those used before surgery. The clinicopathological features of our case are consistent with the diagnosis of unilateral multiple adrenocortical micronodules (UMN), a new subset of primary aldosteronism, in which SAVS proved to be a useful diagnostic tool for its localization.

Aldosterone induces angiotensin converting enzyme gene expression via a JAK2-dependent pathway in rat endothelial cells.

Aldosterone is currently recognized as a risk hormone for cardiovascular disease. However, the cellular mechanism by which aldosterone acts on vasculature has not been well understood. In the present study, we investigated whether aldosterone affects angiotensin-converting enzyme (ACE) gene expression in rat endothelial cells. Cultured rat aortic endothelial cells (RAECs) from Sprague-Dawley rats were used in the study. ACE mRNA levels and its enzyme activities in RAECs were examined by real-time RT-PCR and enzyme assay using hippuryl-His-Leu as substrates, respectively. Aldosterone significantly increased steady-state ACE mRNA levels and its enzymatic activities. This effect was dose dependent and time dependent and abolished by mineralocorticoid receptor antagonist spironolactone or transcription inhibitor actinomycin D. Dexamethasone also increased steady-state ACE mRNA levels, whose effect was completely blocked by glucocorticoid receptor antagonist RU486, but not by spironolactone. By contrast, the aldosterone-induced ACE mRNA expression was only partially blocked by RU486. The stimulatory effect of aldosterone on ACE mRNA expression was completely blocked by a protein tyrosine kinase inhibitor (genistein) and JAK2 inhibitor (AG490), partially by Src kinase inhibitor (PP2) and epidermal growth factor receptor kinase inhibitor (AG1478), but not by platelet-derived growth factor receptor kinase inhibitor (AG1296). Transfection of dominant-negative JAK2 construct, but not wild-type construct, significantly blocked the aldosterone-induced ACE mRNA up-regulation. Furthermore, aldosterone induced phosphorylation of JAK2, whose effect was blocked by spironolactone and actinomycin D. In conclusion, the present study demonstrates for the first time that aldosterone induces ACE gene expression and its enzyme activity mainly via a mineralocorticoid receptor-mediated and JAK2-dependent pathway in rat endothelial cells. This may constitute a positive feedback loop for a local renin-angiotensin system, possibly involved in the development of aldosterone-induced endothelial dysfunction and vascular injury.

Olfactory neuroblastoma causing ectopic ACTH syndrome.

A 39-year-old woman who presented with typical Cushingoid appearance (moon facies, central obesity, purpura) was admitted to our hospital because of pulmonary infection. She was found to have hypertension, severe hypokalemia, and metabolic alkalosis. Endocrine data revealed elevated plasma levels of ACTH and cortisol with lack of circadian rhythm, non-suppressibility to high-dose dexamethasone, and hyperresponsiveness to CRH stimulation. Although no pituitary mass was detected by MRI of the brain, inferior petrosal sinus sampling showed a step-up of central to peripheral ACTH levels; these data are consistent with the diagnosis of Cushing's disease. She was successfully treated with metyrapone to control hypercortisolemia. Ten months later, a mass was detected in the ethmoid sinus, which was surgically removed. After resection of the ethmoid sinus tumor, her Cushingoid features and hypercortisolemia disappeared, but recurred after enlargement of a second mass in the maxillary sinus. After resection of the maxillary sinus tumor, her hypercortisolemia subsided. Histologically, the tumor tissues from both the ethmoid and maxillary sinus were identical and consistent with the diagnosis of olfactory neuroblastoma. Immunohistochemically, the immunoreactivities of ACTH and POMC were positive in the cytoplasm of tumor cells, and immunoreactive ACTH was demonstrated in both tumor tissues. Thus, this is the second rare case with ectopic ACTH syndrome caused by olfactory neuroblastoma thus far reported.