Showing papers on "Adrenal cortex published in 2007"

Pathophysiology of hypercortisolism in depression.

Abstract: Objective: The mechanisms mediating hypercortisolemia in depression remain controversial. Adopting the biomarker strategy, we studied adrenocorticotropin (ACTH) and cortisol dynamics in hypercortisolemic and non-hypercortisolemic depressed in-patients, and in normal volunteers. Method: Deconvolution analysis of 24-h pulsatile secretion, approximate entropy (ApEn) estimation of secretory regularity, cross-ApEn quantitation of forward and reverse ACTH-cortisol synchrony, and cosine regression of 24-h rhythmicity. Results: Hypercortisolemia was strongly associated with melancholic and psychotic depressive subtypes. Hypercortisolemic patients had elevated ACTH and cortisol secretion, mediated chiefly by increased burst masses. Basal ACTH secretion was increased, ACTH half-life was reduced, and mean 24-h ACTH concentration was normal. Cortisol secretion was increased in a highly irregular pattern (high ApEn), with high ACTH -> cortisol cross-ApEn (impaired feedforward coupling). Cortisol-mediated feedback on the secretory pattern of ACTH was normal. Hypercortisolemic depressed patients had normal programming of the central hypothalamo-pituitary-adrenal (HPA) axis pulse generator: ACTH pulse frequency, cortisol pulse frequency, circadian acrophases, and ApEn of ACTH secretion were normal. Responsiveness of the adrenal cortex to endogenous ACTH was normal. Non-hypercortisolemic patients resembled hypercortisolemic patients on ACTH regulatory parameters but had low total cortisol secretion. Conclusion: Increased ACTH secretion occurs in depressed in-patients regardless of cortisolemic status, confirming central HPA axis overdrive in severe depression. Depressive hypercortisolemia results from an additional change in the adrenal cortex that causes ACTH-independent, disorderly basal cortisol release, a sign of physiological stress in melancholic/psychotic depression.

Increased Steroidogenic Factor-1 dosage triggers adrenocortical cell proliferation and cancer.

Abstract: Steroidogenic factor-1 (SF-1/Ad4BP; NR5A1), a nuclear receptor transcription factor, has a pivotal role in adrenal and gonadal development in humans and mice. A frequent feature of childhood adrenocortical tumors is SF-1 amplification and overexpression. Here we show that an increased SF-1 dosage can by itself augment human adrenocortical cell proliferation through concerted actions on the cell cycle and apoptosis. This effect is dependent on an intact SF-1 transcriptional activity. Gene expression profiling showed that an increased SF-1 dosage regulates transcripts involved in steroid metabolism, the cell cycle, apoptosis, and cell adhesion to the extracellular matrix. Consistent with these results, increased SF-1 levels selectively modulate the steroid secretion profile of adrenocortical cells, reducing cortisol and aldosterone production and maintaining dehydroepiandrosterone sulfate secretion. As a model to understand the mechanisms of transcriptional regulation by increased SF-1 dosage, we studied FATE1, coding for a cancer-testis antigen implicated in the control of cell proliferation. Increased SF-1 levels increase its binding to a consensus site in FATE1 promoter and stimulate its activity through modulation of the recruitment of specific cofactors. On the other hand, sphingosine, which can compete with phospholipids for binding to SF-1, had no effect on the SF-1 dosage-dependent increase of adrenocortical cell proliferation and expression of the FATE1 promoter. In mice, increased Sf-1 dosage produces adrenocortical hyperplasia and formation of tumors expressing gonadal markers (Amh, Gata-4), which originate from the subcapsular region of the adrenal cortex. Gene expression profiling revealed that genes involved in cell adhesion and the immune response and transcription factor signal transducer and activator of transcription-3 (Stat3) are differentially expressed in Sf-1 transgenic mouse adrenals compared with wild-type adrenals. Our studies reveal a critical role for SF-1 dosage in adrenocortical tumorigenesis and constitute a rationale for the development of drugs targeting SF-1 transcriptional activity for adrenocortical tumor therapy.

Effects of Cortisol on Carbohydrate, Lipid, and Protein Metabolism: Studies of Acute Cortisol Withdrawal in Adrenocortical Failure

Abstract: Context: Cortisol is an important catabolic hormone, but little is known about the metabolic effects of acute cortisol deficiency. Objective: The objective of the study was to test whether clinical symptoms of weight loss, fatigue, and hypoglycemia could be explained by altered energy expenditure, protein metabolism, and insulin sensitivity during cortisol withdrawal in adrenocortical failure. Design,Participants,andIntervention:Westudiedsevenwomen after 24-h cortisol withdrawal and during replacement control during a 3-h basal period and a 3-h glucose clamp. Results: Cortisol withdrawal generated cortisol levels close to zero, a 10% decrease in basal energy expenditure, increased TSH and T3 levels, and increased glucose oxidation. Whole-body glucose and phenylalanineturnoverwereunaltered,butforearmphenylalanineturnover was increased. During the clamp glucose, infusion rates rose by 70%, glucose oxidation rates increased, and endogenous glucose production decreased. Urinary urea excretion decreased by 40% over the 6-h study period. Conclusions: Cortisol withdrawal increased insulin sensitivity in terms of increased glucose oxidation and decreased endogenous glucose production; this may induce hypoglycemia in adrenocortical failure. Energy expenditure and urea loss decreased, indicating that weight and muscle loss in Addison’s disease is caused by other mechanisms, such as decreased appetite. Increased muscle protein breakdown may amplify the loss of muscle protein. (J Clin Endocrinol Metab 92: 3553–3559, 2007)

Frequent mutations of β‐catenin gene in sporadic secreting adrenocortical adenomas*

Abstract: Objective Molecular alterations remain largely unknown in most sporadic adrenocortical tumours and hyperplasias. In our previous work, we demonstrated the differential expression of several Wnt/beta-catenin signalling-related genes implicated in ACTH-independent macronodular adrenal hyperplasias (AIMAH). To better understand the role of Wnt/beta-catenin signalling in adrenocortical tumours, we performed mutational analysis of the beta-catenin gene. Methods We studied 53 human adrenocortical samples (33 adenomas, 4 carcinomas, 13 AIMAH, 3 ACTH-dependent adrenal hyperplasias) and the human adrenocortical cancer cell line NCI-H295R. All samples were screened for somatic mutations in exons 3 and 5 of the beta-catenin gene. Eleven and six samples were analysed for beta-catenin protein expression by Western blotting and immunohistochemistry, respectively. Results No mutations were detected in adrenocortical carcinomas, AIMAH and ACTH-dependent hyperplasias. Genetic alterations were found in 5 (15%) out of 33 adenomas: three cortisol-secreting adenomas, one aldosterone-secreting adenoma and one nonfunctional adenoma. Two-point mutations occurred at serine residues of codons 37 and 45 (S37C and S45F). The remaining three tumours contained deletions of 6, 55 and 271 bp. H295R cells carry an activating S45P mutation. Western blot analysis of samples with 55- and 271-bp deletions showed an additional shorter and more intense band representing an accumulation of the mutated form of beta-catenin protein. In addition, cytoplasmic and/or nuclear accumulation of beta-catenin was observed in mutated adenomas by immunohistochemistry. Conclusions Activating mutations of exon 3 of the beta-catenin gene are frequent in adrenocortical adenomas, and further characterization of the Wnt/beta-catenin signalling pathway should lead to a better understanding of adrenal tumourigenesis.

Adrenal development is initiated by Cited2 and Wt1 through modulation of Sf-1 dosage

Abstract: It has been proposed that the mammalian adrenal cortex and gonad are derived from the same primordium present during early urogenital development. Molecular pathways involved in the differentiation of the adrenal cortex from the adrenogonadal primordium (AGP) have yet to be determined. Here we show in mice that the transcription co-factor Cited2 is required for the specification of the adrenal cortex from the AGP. We present genetic and molecular evidence demonstrating that Cited2 interacts with the transcription factor Wt1 to stimulate expression of the nuclear hormone receptor Sf-1 (Nr5a1) in the AGP prior to the separation between gonad and adrenal cortex. We show a direct correlation between the expression levels of Sf-1 in the AGP and the defects in adrenal development found in mice with different Cited2 and Wt1 mutant backgrounds. Analysis of embryos heterozygous for mutations in both Sf-1 and Cited2 confirmed that these genes act in the same pathway during adrenal development. Our studies reveal a regulatory mechanism in which Cited2 acts as a Wt1 co-factor to increase, at a critical time in embryogenesis, the levels of the essential transcription factor Sf-1 in the AGP above the threshold required to determine adrenal development. These results highlight the importance of transcription factor dosage in organogenesis and the role of transcription co-factors such as Cited2 in determining the levels of these factors.

Leptin and the regulation of the hypothalamic-pituitary-adrenal axis.

Abstract: Leptin, the product of the obesity gene (ob) predominantly secreted from adipocytes, plays a major role in the negative control of feeding and acts via a specific receptor (Ob-R), six isoforms of which are known at present. Evidence has been accumulated that leptin, like other peptides involved in the central regulation of food intake, controls the function of the hypothalamic-pituitary-adrenal (HPA) axis, acting on both its central and peripheral branches. Leptin, along with Ob-R, is expressed in the hypothalamus and pituitary gland, where it modulates corticotropin-releasing hormone and ACTH secretion, probably acting in an autocrine-paracrine manner. Only Ob-R is expressed in the adrenal gland, thereby making it likely that leptin affects it by acting as a circulating hormone. Although in vitro and in vivo findings could suggest a glucocorticoid secretagogue action in the rat, the bulk of evidence indicates that leptin inhibits steroid-hormone secretion from the adrenal cortex. In keeping with this, leptin was found to dampen the HPA axis response to many kinds of stress. In contrast, leptin enhances catecolamine release from the adrenal medulla. This observation suggests that leptin activates the sympathoadrenal axis and does not appear to agree with its above-mentioned antistress action. Leptin and/or Ob-R are also expressed in pituitary and adrenal tumors, but little is known about the role of this cytokine in the pathophysiology.

Adrenocortical dysregulation as a major player in insulin resistance and onset of obesity.

Abstract: The aim of this review is to explore the dysregulation of adrenocortical secretions as a major contributor in the development of obesity and insulin resistance. Disturbance of adipose tissue physiology is one of the primary events in the development of pathologies associated with the metabolic syndrome, such as obesity and type 2 diabetes. Several studies indicate that alterations in metabolism of glucocorticoids (GC) and androgens, as well as aldosterone in excess, are involved in the emergence of metabolic syndrome. Cross talk among adipose tissue, the hypothalamo-pituitary complex, and adrenal gland activity plays a major role in the control of food intake, glucose metabolism, lipid storage, and energy balance. Perturbation of this cross talk induces alterations in the regulatory mechanisms of adrenocortical steroid synthesis, secretion, degradation, and/or recycling, at the level of the zonae glomerulosa (aldosterone), fasciculata (GC and GC metabolites), and reticularis (androgens and androgen precursors DHEA and DHEAS). As a whole, these adrenocortical perturbations contribute to the development of metabolic syndrome at both the paracrine and systemic level by favoring the physiological dysregulation of organs responsive to aldosterone, GC, and/or androgens, including adipose tissue.

Growth analysis of the mouse adrenal gland from weaning to adulthood: time- and gender-dependent alterations of cell size and number in the cortical compartment

Abstract: The adrenal gland is of critical importance for a plethora of biological processes. We performed the first systematic analysis of adrenal gland growth using unbiased stereological methods in male and female mice from weaning to adulthood (weeks 3, 5, 7, 9, and 11) at the organ, compartment, and cellular levels. Adrenal weights increased from week 3 to week 7 in male and female mice, remained at this level in females, but decreased by 25% between week 7 and week 9 in males. Female adrenal glands displayed a higher weight at any stage investigated. The volume of the zona fasciculata was consistently higher in female vs. male mice. In both genders, the number of zona fasciculata cells reached a maximum at the age of 7 wk and decreased significantly until week 9. Serum corticosterone concentrations decreased from 3 to 11 wk of age both in male and female mice. However, the estimated total amounts of corticosterone in the circulation were similar in 3- and 11-wk-old mice. Furthermore, total circulating corticosterone was higher in females than in males at an age of 5 and 11 wk. In the zona glomerulosa and in the X-zone, time- and gender-dependent growth effects were observed. In conclusion, our results demonstrate that growth and function of the adrenal glands are markedly influenced by gender and age. These factors require careful consideration in studies aiming at the functional dissection of genetic and environmental factors affecting adrenal growth and function.

Adrenal 20α-Hydroxysteroid Dehydrogenase in the Mouse Catabolizes Progesterone and 11-Deoxycorticosterone and Is Restricted to the X-Zone

Abstract: The enzyme 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) is a progesterone-catabolizing enzyme that is highly expressed in mouse ovaries and adrenals. Although the functional significance of ovarian 20alpha-HSD for the induction of parturition has been defined, regulation and distribution of 20alpha-HSD in the adrenal gland has not been determined. We demonstrate that the expression of adrenal 20alpha-HSD is restricted to the X-zone, a transient zone between the adrenal cortex and the medulla of yet unknown function. Adrenal 20alpha-HSD activity in male mice peaks at 3 wk of age and disappears thereafter, whereas 20alpha-HSD enzyme activity is maintained in adrenals from nulliparous female animals. Testosterone treatment of female mice induces rapid involution of the X-zone that is associated with the disappearance of the 20alpha-HSD-positive cells. Conversely, reappearance of 20alpha-HSD expression and activity in male animals is evident after gonadectomy. Moreover, pregnancy, but not pseudopregnancy, is accompanied by X-zone regression and loss of 20alpha-HSD activity. Pregnancy-induced X-zone regression and -abolished 20alpha-HSD expression is partially restored in animals that were kept from nursing their pups. We found that in addition to its progesterone-reducing activity, 20alpha-HSD also functions as an 11-deoxycorticosterone-catabolizing enzyme. The unaltered growth kinetics of the X-zone in 20alpha-HSD knockout animals suggests that 20alpha-HSD is not required for the regulation of X-zone growth. However, 20alpha-HSD expression and enzymatic activity in all experimental paradigms is closely correlated with the presence of the X-zone. These findings provide the basis for 20alpha-HSD as a reliable marker of the murine X-zone.

Adipocyte-derived products induce the transcription of the StAR promoter and stimulate aldosterone and cortisol secretion from adrenocortical cells through the Wnt-signaling pathway

Abstract: Adipocyte-derived products induce the transcription of the StAR promoter and stimulate aldosterone and cortisol secretion from adrenocortical cells through the Wnt-signaling pathway

Activation of Pregnane X Receptor Disrupts Glucocorticoid and Mineralocorticoid Homeostasis

Abstract: The pregnane X receptor (PXR) was isolated as a xenobiotic receptor that regulates responses to various xenobiotic agents. In this study, we show that PXR plays an important endobiotic role in adrenal steroid homeostasis. Activation of PXR by genetic (transgene) or pharmacological (ligand, such as rifampicin) markedly increased plasma concentrations of corticosterone and aldosterone, the respective primary glucocorticoid and mineralocorticoid in rodents. The increased levels of corticosterone and aldosterone were associated with activation of adrenal steroidogenic enzymes, including cytochrome P450 (CYP)11a1, CYP11b1, CYP11b2, and 3beta-hydroxysteroid dehydrogenase. The PXR-activating transgenic mice also exhibited hypertrophy of the adrenal cortex, loss of glucocorticoid circadian rhythm, and lack of glucocorticoid responses to psychogenic stress. Interestingly, the transgenic mice had normal pituitary secretion of ACTH and the corticosterone-suppressing effect of dexamethasone was intact, suggesting a functional hypothalamus-pituitary-adrenal axis despite a severe disruption of adrenal steroid homeostasis. The ACTH-independent hypercortisolism in the PXR-activating transgenic mice is reminiscent of the pseudo-Cushing's syndrome in patients. The glucocorticoid effect appears to be PXR specific, as the activation of constitutive androstane receptor in transgenic mice had little effect. We propose that PXR is a potential endocrine disrupting factor that may have broad implications in steroid homeostasis and drug-hormone interactions.

Adrenal toxicology: a strategy for assessment of functional toxicity to the adrenal cortex and steroidogenesis.

Abstract: The adrenal is the most common toxicological target organ in the endocrine system in vivo and yet it is neglected in regulatory endocrine disruption screening and testing. There has been a recent marked increase in interest in adrenal toxicity, but there are no standardised approaches for assessment. Consequently, a strategy is proposed to evaluate adrenocortical toxicity. Human adrenal conditions are reviewed and adrenocortical suppression, known to have been iatrogenically induced leading to Addisonian crisis and death, is identified as the toxicological hazard of most concern. The consequences of inhibition of key steroidogenic enzymes and the possible toxicological modulation of other adrenal conditions are also highlighted. The proposed strategy involves an in vivo rodent adrenal competency test based on ACTH challenge to specifically examine adrenocortical suppression. The H295R human adrenocortical carcinoma cell line is also proposed to identify molecular targets, and is useful for measuring steroids, enzymes or gene expression. Hypothalamo-pituitary-adrenal endocrinology relevant to rodent and human toxicology is reviewed (with an emphasis on multi-endocrine axis effects on the adrenal and also how the adrenal affects a variety of other hormones) and the endocrinology of the H295R cell line is also described. Chemicals known to induce adrenocortical toxicity are reviewed and over 60 examples of compounds and their confirmed steroidogenic targets are presented, with much of this work published very recently using H295R cell systems. In proposing a strategy for adrenocortical toxicity assessment, the outlined techniques will provide hazard assessment data but it will be regulatory agencies that must consider the significance of such data in risk extrapolation models. The cases of etomindate and aminoglutethimide induced adrenal suppression are clearly documented examples of iatrogenic adrenal toxicity in humans. Environmentally, sentinel species, such as fish, have also shown evidence of adrenal endocrine disruption attributed to exposure to chemicals. The extent of human sub-clinical adrenal effects from environmental chemical exposures is unknown, and the extent to which environmental chemicals may act as a contributory factor to human adrenal conditions following chronic low-level exposures will remain unknown unless purposefully studied.

Disabled-2 Is Expressed in Adrenal Zona Glomerulosa and Is Involved in Aldosterone Secretion

Abstract: The differentiation of the adrenal cortex into functionally specific zones is probably due to differential temporal gene expression during fetal growth, development, and adulthood. In our search for adrenal zona glomerulosa-specific genes, we found that Disabled-2 (Dab2) is expressed in the zona glomerulosa of the rat adrenal gland using a combination of laser capture microdissection, mRNA amplification, cDNA microarray hybridization, and real-time RT-PCR. Dab2 is an alternative spliced mitogen-regulated phosphoprotein with features of an adaptor protein and functions in signal transduction, endocytosis, and tissue morphogenesis during embryonic development. We performed further studies to analyze adrenal Dab2 localization, regulation, and role in aldosterone secretion. We found that Dab2 is expressed in the zona glomerulosa and zona intermedia of the rat adrenal cortex. Low-salt diet treatment increased Dab2-long isoform expression at the mRNA and protein level in the rat adrenal gland, whereas high-salt...

Characterisation of CART-containing neurons and cells in the porcine pancreas, gastro-intestinal tract, adrenal and thyroid glands.

Abstract: The peptide CART is widely expressed in central and peripheral neurons, as well as in endocrine cells. Known peripheral sites of expression include the gastrointestinal (GI) tract, the pancreas, and the adrenal glands. In rodent pancreas CART is expressed both in islet endocrine cells and in nerve fibers, some of which innervate the islets. Recent data show that CART is a regulator of islet hormone secretion, and that CART null mutant mice have islet dysfunction. CART also effects GI motility, mainly via central routes. In addition, CART participates in the regulation of the hypothalamus-pituitary-adrenal-axis. We investigated CART expression in porcine pancreas, GI-tract, adrenal glands, and thyroid gland using immunocytochemistry. CART immunoreactive (IR) nerve cell bodies and fibers were numerous in pancreatic and enteric ganglia. The majority of these were also VIP IR. The finding of intrinsic CART containing neurons indicates that pancreatic and GI CART IR nerve fibers have an intrinsic origin. No CART IR endocrine cells were detected in the pancreas or in the GI tract. The adrenal medulla harboured numerous CART IR endocrine cells, most of which were adrenaline producing. In addition CART IR fibers were frequently seen in the adrenal cortex and capsule. The capsule also contained CART IR nerve cell bodies. The majority of the adrenal CART IR neuronal elements were also VIP IR. CART IR was also seen in a substantial proportion of the C-cells in the thyroid gland. The majority of these cells were also somatostatin IR, and/or 5-HT IR, and/or VIP IR. CART is a major neuropeptide in intrinsic neurons of the porcine GI-tract and pancreas, a major constituent of adrenaline producing adrenomedullary cells, and a novel peptide of the thyroid C-cells. CART is suggested to be a regulatory peptide in the porcine pancreas, GI-tract, adrenal gland and thyroid.

Mechanisms of Disease: the role of aldosterone in kidney damage and clinical benefits of its blockade

Abstract: In the past 10 years, many widely accepted concepts relating to aldosterone production and its pathogenetic role have changed. We now know that aldosterone is produced not only by the zona glomerulosa of the adrenal cortex, but also in the heart, blood vessels, kidney and brain; such extra-epithelial production occurs mainly during tissue repair. Also, increased aldosterone levels contribute to vessel inflammation, oxidative stress, endothelial dysfunction and organ damage. As such, aldosterone has a key role in the development of myocardial fibrosis. Anti-aldosterone treatment has proven effective in patients with heart failure. Experimental evidence regarding the role of aldosterone in kidney damage has accumulated. Aldosterone infusion can counteract the beneficial effects of treatment with angiotensin-converting-enzyme inhibitors, causing more-severe proteinuria and an increased number of vascular and glomerular lesions; treatment with aldosterone antagonists can reverse these alterations. Preliminary observations in pilot studies in humans confirm the experimental findings, supporting the hypothesis that aldosterone antagonists are renoprotective in clinical practice. Studies in larger populations with longer follow-up are needed to confirm this theory.

Tumor Necrosis Factor-α Regulates Steroidogenesis, Apoptosis, and Cell Viability in the Human Adrenocortical Cell Line NCI-H295R

Abstract: TNF-α regulates the hypothalamo-pituitary-adrenal axis at several levels. It has been shown to modify adrenal steroidogenesis in many species, and it is supposed to act as an auto/paracrine factor. However, its significance in human adrenocortical function remains unclear. Therefore, we investigated the effect of TNF-α on adrenal steroidogenesis, expression of the key steroidogenic genes, apoptosis, and cell viability in the human adrenocortical cell line NCI-H295R. TNF-α treatment (1 nm for 48 h) decreased the basal production of cortisol, androstenedione, dehydroepiandrosterone sulfate (DHEAS), and aldosterone (14, 18, 35, and 52%, respectively), and the 8-bromo-cAMP-induced production of cortisol, androstenedione, dehydroepiandrosterone (DHEA), and DHEAS (44, 66, 58, and 48%, respectively). However, when the steroid production data were normalized by the cell number, TNF-α increased the basal production of cortisol, androstenedione, DHEA, DHEAS, and aldosterone (137, 121, 165, 73, and 28%, respectively...

Genetic Removal of Smad3 from Inhibin-Null Mice Attenuates Tumor Progression by Uncoupling Extracellular Mitogenic Signals from the Cell Cycle Machinery

Abstract: Inhibin and activin are members of the TGFbeta family that perform mutually antagonistic signaling roles in the anterior pituitary, gonads, and adrenal gland. Unopposed activin signaling in inhibin-null (Inha-/-) mice causes the formation of granulosa cell tumors in the gonads and adrenal cortex, which depend upon FSH for efficient growth and progression. In this study, we demonstrate that Smad3, a key effector of activin signaling, is expressed at high levels and is constitutively activated in tumors from these mice. Removal of Smad3 from Inha-/- mice by a genetic cross to Smad3-null (Madh3-/-) mice leads to a significant decrease in cyclinD2 expression and a significant attenuation of tumor progression in the gonads and adrenal. The decrease in cyclinD2 levels in compound knockout mice is related to a reduction in mitogenic signaling through the phosphoinositide-3-kinase (PI3-kinase)/Akt pathway, which is required for normal cell cycle progression in tumor cells. Loss of PI3-kinase/Akt signaling cannot be attributed to alterations in IGF expression, suggesting instead that signaling through the FSH receptor is attenuated. Gene expression profiling in the ovaries of Madh3-/- and Inha-/-:Madh3-/- compound knockout mice supports this hypothesis and further suggests that Smad3 is specifically required for FSH to activate PI3-kinase/Akt, but not protein kinase A. Together these observations imply that activin/Smad3 signaling is necessary for efficient signaling by FSH in Inha-/- tumor cells and that interruption of this pathway uncouples FSH from its intracellular mitogenic effectors.

Neuroendocrine profiling in inherited stress-induced arterial hypertension rat strain with stress-sensitive arterial hypertension.

Abstract: The functions of the hypothalamic adrenal cortical and sympathetic adrenal medullary systems were studied in rats with inherited stress-induced arterial hypertension (ISIAH strain). A characteristic feature of the ISIAH strain is an increase in arterial blood pressure measured both under basal conditions and after restraint stress in particular. In the control ISIAH rats, the basal plasma ACTH concentration was slightly lower than that in the normotensive Wistar albino Glaxo (WAG) rats, and no differences were found in plasma corticosterone. However, the 0.5-h restraint stress produced higher activation of the adrenal cortex in the ISIAH rats. Gluco- and mineralocorticoid responses to the blood volume reduction stresses and ACTH and corticosterone responses to social stress were stronger in the ISIAH than in the control WAG rats. An increase in epinephrine content in adrenals in the basal state and enhanced response of the sympathetic adrenal medullary system to handling stress were observed in the ISIAH rats. Restraint stress produced significantly higher expression of genes encoding corticotropin-releasing hormone-mRNA in hypothalamus and proopiomelanocortin-mRNA in pituitary in the ISIAH than in the WAG rats. Restraint stress produced a decrease in glucocorticoid receptor (GR) gene expression (GR-mRNA) in hippocampus in the ISIAH, but not in the WAG rats. A persistent increase in tyrosine hydroxylase-mRNA in adrenals of the ISIAH rats was found. It is concluded that the ISIAH rat strain is an appropriate model of stress-sensitive hypertension with the predominant involvement of the hypothalamic adrenal cortical and sympathetic adrenal medullary systems in its pathogenesis.

Ghrelin and its unacylated isoform stimulate the growth of adrenocortical tumor cells via an anti-apoptotic pathway.

Abstract: Ghrelin is expressed in normal human adrenocortical cells and induces their proliferation through growth hormone secretagogue receptor 1a (GHS-R1a). Consequently, it was of interest to us to determ...

Nephroblastoma overexpressed/cysteine-rich protein 61/connective tissue growth factor/nephroblastoma overexpressed gene-3 (NOV/CCN3), a selective adrenocortical cell proapoptotic factor, is down-regulated in childhood adrenocortical tumors.

Abstract: Context: Childhood adrenocortical tumors (ACTs) have a fetal adrenal phenotype and overexpress steroidogenic factor-1 (SF-1). Nephroblastoma overexpressed (NOV)/cysteine-rich protein 61/connective tissue growth factor/nephroblastoma overexpressed gene-3 mRNA is significantly down-regulated in childhood ACTs. Objective: The objective of the study was to measure NOV protein levels in childhood ACTs and characterize NOV expression regulation and biological function in human adrenocortical cells. Design and Setting: Protein extracts from ACT and normal adrenal cortex samples, human adrenocortical carcinoma H295R, primary adrenocortical tumors and fetal adrenal cultures, tissue culture supernatants, and cell lysates from H295R cells overexpressing SF-1 in an inducible fashion were used. Main Outcome Measures: NOV protein levels were measured by enzyme-linked immunoassay and immunoblot. Transient transfection assays were used to study the activity of NOV promoter. Terminal deoxynucleotidyl transferase-mediated ...

Human adrenal corticocarcinoma NCI-H295R cells produce more androgens than NCI-H295A cells and differ in 3beta-hydroxysteroid dehydrogenase type 2 and 17,20 lyase activities.

Abstract: The human adrenal cortex produces mineralocorticoids, glucocorticoids, and androgens in a species-specific, hormonally regulated, zone-specific, and developmentally characteristic fashion. Most molecular studies of adrenal steroidogenesis use human adrenocortical NCI-H295A and NCI-H295R cells as a model because appropriate animal models do not exist. NCI-H295A and NCI-H295R cells originate from the same adrenocortical carcinoma which produced predominantly androgens but also smaller amounts of mineralocorticoids and glucocorticoids. Research data obtained from either NCI-H295A or NCI-H295R cells are generally compared, although for the same experiments no direct comparison between the two cell lines has been performed. Therefore, we compared the steroid profile and the expression pattern of important genes involved in steroidogenesis in both cell lines. We found that steroidogenesis differs profoundly. NCI-H295A cells produce more mineralocorticoids, whereas NCI-H295R cells produce more androgens. Expression of the 3beta-hydroxysteroid dehydrogenase (HSD3B2), cytochrome b5, and sulfonyltransferase genes is higher in NCI-H295A cells, whereas expression of the cytochrome P450c17 (CYP17), 21-hydroxylase (CYP21), and P450 oxidoreductase genes does not differ between the cell lines. We found lower 3beta-hydroxysteroid dehydrogenase type 2 but higher 17,20-lyase activity in NCI-H295R cells explaining the 'androgenic' steroid profile for these cells and resembling the zona reticularis of the human adrenal cortex. Both cell lines were found to express the ACTH receptor at low levels consistent with low stimulation by ACTH. By contrast, both cell lines were readily stimulated by 8Br-cAMP. The angiotensin type 1 receptor was highly expressed in NCI-H295R than NCI-H295A cells and angiotensin II stimulated steroidogenesis in NCI-H295R but not NCI-H295A cells. Our data suggest that comparative studies between NCI-H295A and NCI-H295R cells may help find important regulators of mineralocorticoid or androgen biosynthesis.

Pre-B-cell transcription factor 1 and steroidogenic factor 1 synergistically regulate adrenocortical growth and steroidogenesis.

Abstract: A variety of transcription factors including Wilms tumor gene (Wt-1), steroidogenic factor 1 (Sf-1), dosage-sensitive sex reversal, adrenal hypoplasia congenita on the X-chromosome, Gene 1 (Dax-1), and pre-B-cell transcription factor 1 (Pbx1) have been defined as necessary for regular adrenocortical development. However, the role of Pbx1 for adrenal growth and function in the adult organism together with the molecular relationship between Pbx1 and these other transcription factors have not been characterized. We demonstrate that Pbx haploinsufficiency (Pbx1+/−) in mice is accompanied by a significant lower adrenal weight in adult animals compared with wild-type controls. Accordingly, baseline proliferating cell nuclear antigen levels are lower in Pbx1+/− mice, and unilateral adrenalectomy results in impaired contralateral compensatory adrenal growth, indicating a lower proliferative potential in the context of Pbx1 haploinsufficiency. In accordance with the key role of IGFs in adrenocortical proliferation...

Differential regulation of glucocorticoid synthesis in murine intestinal epithelial versus adrenocortical cell lines.

Abstract: Glucocorticoids are steroid hormones with important functions in development, immune regulation, and glucose metabolism. The adrenal glands are the predominant source of glucocorticoids; however, there is increasing evidence for extraadrenal glucocorticoid synthesis in thymus, brain, skin, and vascular endothelium. We recently identified intestinal epithelial cells as an important source of glucocorticoids, which regulate the activation of local intestinal immune cells. The molecular regulation of intestinal glucocorticoid synthesis is currently unexplored. In this study we investigated the transcriptional regulation of the steroidogenic enzymes P450 side-chain cleavage enzyme and 11beta-hydroxylase, and the production of corticosterone in the murine intestinal epithelial cell line mICcl2 and compared it with that in the adrenocortical cell line Y1. Surprisingly, we observed a reciprocal stimulation pattern in these two cell lines. Elevation of intracellular cAMP induced the expression of steroidogenic enzymes in Y1 cells, whereas it inhibited steroidogenesis in mICcl2 cells. In contrast, phorbol ester induced steroidogenic enzymes in intestinal epithelial cells, which was synergistically enhanced upon transfection of cells with the nuclear receptors steroidogenic factor-1 (NR5A1) and liver receptor homolog-1 (NR5A2). Finally, we observed that basal and liver receptor homolog-1/phorbol ester-induced expression of steroidogenic enzymes in mICcl2 cells was inhibited by the antagonistic nuclear receptor small heterodimer partner. We conclude that the molecular basis of glucocorticoid synthesis in intestinal epithelial cells is distinct from that in adrenal cells, most likely representing an adaptation to the local environment and different requirements.

Transcriptional regulation of adrenocortical steroidogenic gene expression.

Abstract: By serving as ligands for nuclear and plasma membrane receptors, steroid hormones are key regulators of a diverse array of physiological processes. These hormones are synthesized from cholesterol in tissues such as the adrenal cortex, ovaries, testes, and placenta. Because steroid hormones control the expression of numerous genes, steroidogenic cells utilize multiple mechanisms that ensure tight control of the synthesis of these molecules. This review will give an overview of the molecular mechanisms by which the expression of steroidogenic genes is regulated in the human adrenal cortex.

Down-Regulation of D2 Dopamine Receptor and Increased Protein Kinase Cμ Phosphorylation in Aldosterone-Producing Adenoma Play Roles in Aldosterone Overproduction

Abstract: Context: The mechanism associated with the overproduction of aldosterone by aldosterone-producing adenomas (APA) is unknown. Objective: The objective of the study was to explore the role of the D2 dopamine receptor (D2R) on aldosterone synthesis and secretion and clarify the clinical importance of this role on aldosterone overproduction in APA. Results: D2R expression in APA was examined in 24 patients and was much less than that in the nontumorous adrenal cortex. D2R mRNA levels in APA were inversely correlated with CYP11B2 mRNA levels and the patient’s plasma aldosterone concentration. Angiotensin II (AII)-stimulated aldosterone secretion and CYP11B2 mRNA expression in human adrenocarcinoma cells (H295R) was attenuated by the D2 agonist, bromocriptine (BMC). BMC selectively attenuated AII-induced protein kinase C (PKC)-μ phosphorylation and its translocation to the cell membrane. PKCμ-specific short-hairpin RNA significantly decreased AII-induced CYP11B2 mRNA expression and aldosterone secretion. BMC al...

Physiological roles of prolactin in the adrenocortical response to acute restraint stress.

Abstract: The present study characterized the different hormonal responses to stress in the endocrine milieu with different circulating levels of prolactin (PRL) and examined the direct effects of PRL on adrenal steroidogenic responses to adrenocorticotropic hormone (ACTH) using experimentally induced hyperprolactinemia and hypoprolactinemia male rat models Hyperprolactinemia was induced by transplantation of two adult female rat anterior pituitary glands under the kidney capsule for 2 weeks, and hypoprolactinemia was induced by daily subcutaneous injection of 2-Bromo-alpha-Ergocryptine (CB-154) for 2 weeks Under stress conditions, the peak levels of ACTH were significantly higher in hypoprolactinemia than normal rats Meanwhile, the peak levels of corticosterone and progesterone were significantly higher in hyperprolactinemia than in normal and hypoprolactinemia stressed rats Results of in vitro experiments showed that adrenocortical cells in hyperprolactinemia exhibited higher basal levels of corticosterone and progesterone rats than normal and hypoprolactinemia rats The stimulatory effect of ACTH on corticosterone and progesterone release was higher in hyperprolactinemia than hypoprolactinemia rats In addition, PRL increased the stimulatory effect of ACTH-induced corticosterone secretion in all rat models These results suggest that hypoprolactinemia and hyperprolactinemia rats exhibit marked differences in the response of their hypothalamic-pituitary-adrenal (HPA) axis during acute restrain stress Additionally, these studies emphasize that the adrenal cortex might be more sensitive to ACTH stimulation in endocrine milieu with high levels of PRL resulting in high corticosterone and progesterone release

Galanin in the regulation of the hypothalamic-pituitary-adrenal axis (Review).

Abstract: Galanin is a regulatory 30- or 29-amino acid peptide, widely distributed in the nervous system and gut, that acts via three subtypes of G protein-coupled receptors, named GAL-R1, GAL-R2 and GAL-R3. Findings have been accumulated that galanin regulates neuroendocrine hypothalamic axes, including the hypothalamic-pituitary-adrenal (HPA) one. Galanin and its receptors are expressed in the hypothalamic paraventricular and supraoptic nuclei, anterior pituitary and adrenal medulla. Adrenal cortex does not express galanin, but is provided with GAL-R1 and GAL-R2. The bulk of evidence indicates that galanin stimulates the activity of the central branch of the HPA axis (i.e. the release of corticotropin-releasing hormone and ACTH), thereby enhancing glucocorticoid secretion from the adrenal cortex. Investigations carried out in the rat show that galanin is also able to directly stimulate corticosterone (glucocorticoid) secretion from adrenocortical cells, through GAL-R1 and GAL-R2 coupled to the adenylate cyclase-protein kinase A signaling cascade, and nor-epinephrine release from adrenal medulla. There is indication that galanin may also enhance corticosterone release via an indirect paracrine mechanism involving the local release of catecholamines, which in turn activate beta-adrenoceptors located on adrenocortical cells. The physiological relevance in the rat of the glucocorticoid secretagogue action of galanin is suggested by the demonstration that the blockade of galanin system significantly lowers basal corticosterone secretion. There is also evidence that galanin plays a role in the modulation of HPA-axis response to stress, as well as in the pathogenesis of pituitary adenomas and perhaps of pheochromocytomas.