Showing papers on "Adrenal cortex published in 1993"
TL;DR: It is hypothesized that during amitriptyline treatment a rise in limbic MR may be the initial phenomenon in a successively adjusting HPA system, as evidenced by the decreasing plasma hormone concentrations, declining adrenal size, and up-regulation of GR in particular brain regions.
Abstract: The effects of the tricyclic antidepressant amitriptyline on the rat hypothalamic-pituitary-adrenocortical (HPA) system were studied. The time-course experiments showed that amitriptyline, given via the drinking water (4.5 mg/kg.day), produces significant decreases (P < 0.05) in adrenal weight after 5 (-20%) and 7 weeks (-21%) of treatment. Hippocampal mineralocorticoid receptor (MR) levels were down-regulated at days 3 (-27%) and 7 (-20%), and transiently up-regulated at 2 (+40%), 5 (+74%), and 7 (+18%) weeks of treatment. Hippocampal glucocorticoid receptor (GR) levels were slightly down-regulated at days 3 (-8%) and 7 (-17%), transiently up-regulated by 26% at 5 weeks, and indistinguishable from controls after 7 weeks of treatment. MR levels were unchanged in the hypothalamus and neocortex, whereas hypothalamic GR concentrations were elevated and neocortical receptor levels were not altered. Dose-response experiments showed significant decreases in adrenal weight when rats were treated with 4.5 (-14%), 8.8 (-16%) and 14.5 (-13%) mg/kg.day antidepressant, but this applied only for the 4.5- (-14%) and 8.8- (-12%) mg/kg.day doses when the ratio of adrenal weight to body weight was considered. The dose-response relationship regarding hippocampal GR content displayed an inverted U-shaped curve, whereas this was less marked for MR levels. A dose of 4.5 mg/kg.day appeared to be optimal for the rise in MR as well as GR. Concerning the neuroendocrine implications of chronic antidepressant treatment, amitriptyline (5 weeks, 4.5 mg/kg.day) produced significant decreases in basal (ACTH, -47%; corticosterone, -31%) as well as stress (30 min novel environment)-induced plasma ACTH (-38%) and corticosterone (-57%) levels. Previous experiments have forwarded a role of limbic MR in the tonic control of basal HPA activity. Based on the present data, we hypothesize that during amitriptyline treatment a rise in limbic MR may be the initial phenomenon in a successively adjusting HPA system, as evidenced by the decreasing plasma hormone concentrations, declining adrenal size, and up-regulation of GR in particular brain regions.
356 citations
TL;DR: Restraint stress induces the expression of the major heat shock protein, HSP70, in the adrenal cortex of the rat, and it is demonstrated that restraint also induces expression of HSP 70 in the vasculature.
Abstract: Adaptation to stress requires coordinated interactions between the vascular and endocrine systems. Previously we demonstrated that restraint stress induces the expression of the major heat shock protein, HSP70, in the adrenal cortex of the rat. Here we demonstrate that restraint also induces expression of HSP70 in the vasculature. We further demonstrate that the adrenal and vascular responses are differentially regulated: the adrenal response is adrenocorticotropin dependent, whereas the vascular response is under adrenergic control. In addition, the adrenal response is restricted to members of the HSP70 gene family, whereas in vascular tissue the low molecular weight HSP, HSP27, is also induced by restraint. Further characterization of the vascular response revealed that HSP70 induction occurred in both the thoracic and abdominal aortas as well as in the vena cava. However, no HSP70 induction was apparent in the heart or in a wide variety of other tissues examined. In situ hybridization showed that the vascular expression was localized to the aortic smooth muscle cells with minimal expression in the endothelium. Induction of HSP70 mRNA in both the adrenal cortex and aorta was followed by an elevation in HSP70 protein. Maximum HSP70 protein levels were seen within 3-12 h after restraint, but declined thereafter. Stress induced HSP70 expression was dramatically reduced with age, which may explain, in part, the diminished tolerance to stress seen in elderly individuals.
215 citations
TL;DR: These studies show that NCI-H295 cells express most of the enzymes needed for human adrenal steroidogenesis, and that the genes encoding these enzymes respond to stimulation of second messenger pathways in a manner similar to that of human adrenals.
Abstract: NCI-H295 is a recently described human adrenocortical carcinoma cell line that makes a variety of steroid hormones. We sought to determine if steroidogenesis in these cells employs the same enzymes as those used in normal adrenal steroidogenesis, and if the genes encoding those enzymes exhibit characteristic responsiveness to activators of the protein kinase-A and -C pathways of intracellular second messengers. Northern blots show that NCI-H295 cells contain abundant mRNAs for three key steroidogenic enzymes, cytochrome P450scc, cytochrome P450c17, and cytochrome P450c21. These mRNAs accumulated in a time- and dose-dependent fashion in response to 8-bromo-cAMP (8Br-cAMP), forskolin, cholera toxin, and 3-isobutyl-1-methylxanthine, all activators of the protein kinase-A pathway. Nuclear run-on assays and actinomycin-D transcriptional inhibition experiments show that cAMP regulates the expression of all three genes primarily at the transcriptional level. Inhibition of protein synthesis with cycloheximide did not prevent the cAMP-induced accumulation of P450scc or P450c17 mRNAs, but did inhibit accumulation of P450c21 mRNA, suggesting that cAMP is acting through a mechanism dependent on protein synthesis to promote accumulation of P450c21 mRNA. Stimulation of the protein kinase-C pathway with phorbol ester decreased P450scc and P450c17 mRNAs, but stimulated the accumulation of P450c21 mRNA. RNase protection experiments, Northern blot hybridizations, and reverse transcription-polymerase chain reaction show that NCI-H295 cells express both the 11 beta-hydroxylase (P450c11 beta) encoded by the P450c11B1 gene and the aldosterone synthetase (P450c11AS) encoded by the P450c11B2 gene. 8Br-cAMP increased the abundance of both of these mRNAs with similar kinetics, with maximal accumulation of both after about 24 h. NCI-H295 cells also contain the mRNAs for aromatase and insulin-like growth factor-II. 8Br-cAMP increased the abundance of aromatase mRNA and decreased the abundance of IGF-II mRNA. These studies show that NCI-H295 cells express most of the enzymes needed for human adrenal steroidogenesis, and that the genes encoding these enzymes respond to stimulation of second messenger pathways in a manner similar to that of human adrenals. NCI-H295 cells appear to be a good model for studying the molecular regulation of human adrenal steroidogenesis.
213 citations
TL;DR: An adrenocortical carcinoma cell line, NCI-H295, is described, which provides a suitable angiotensin-II (AII)-responsive model system to investigate the acute and chronic regulation of aldosterone synthesis and release.
Abstract: Excessive secretion of aldosterone from the adrenal results in the most common form of endocrine hypertension. An understanding of the regulatory processes involved in aldosterone synthesis and release is needed to define the biomolecular mechanisms controlling excessive production of aldosterone. However, in vitro studies regarding the regulatory mechanisms of human aldosterone production have been limited because of difficulties in obtaining tissue and the subsequent isolation of aldosterone-secreting glomerulosa cells. Herein we describe an adrenocortical carcinoma cell line, NCI-H295, which provides a suitable angiotensin-II (AII)-responsive model system to investigate the acute and chronic regulation of aldosterone synthesis. The cells were characterized with regard to the effects of AII on second messenger systems, aldosterone release, and levels of aldosterone synthase (P450c18) mRNA. In the presence of lithium, AII caused a rapid, but transient, increase in the production of inositol tris- and bisphosphates, whereas a prolonged gradual accumulation of inositol monophosphate occurred. Treatment with AII resulted in a 4.5-fold increase in total inositol phosphates in a concentration-dependent manner and an increase in intracellular cytoplasmic free Ca2+. Significant increases in aldosterone (3.5-fold) were detected within 1 h of AII addition. Aldosterone release occurred in a concentration-and time-dependent manner. The type 1 AII (AT1) receptor was shown to be responsible for activation of phosphoinositidase-C, increased intracellular free Ca2+, and aldosterone production, as determined by use of the AT1 receptor antagonist DuP753. In addition, AII treatment resulted in a time-dependent increase in levels of P450c18 mRNA, as detected by RNAse protection assay. In summary, NCI-H295 cells provide a valuable model system to define mechanisms regulating human aldosterone production.
187 citations
TL;DR: In this paper, the in situ localization of key steroidogenic enzymes in adrenal gland sections from midgestation (17-24 weeks) human fetuses and late gestation (130-142 days; term = 165 days) rhesus monkey fetuses was examined.
Abstract: We examined the in situ localization of key steroidogenic enzymes in adrenal gland sections from midgestation (17-24 weeks) human fetuses and late gestation (130-142 days; term = 165 days) rhesus monkey fetuses. The rhesus monkey fetal adrenals were used as a model for the late gestation human fetal adrenal. The enzymes examined were cytochrome P450 cholesterol side-chain cleavage (P450scc), cytochrome P450 17 alpha-hydroxylase/17,20-lyase (P450c17), and 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta HSD). In human fetal adrenals, P450scc and P450c17 proteins and mRNAs were detected only in fetal zone (innermost cortical zone) and transitional zone (between the fetal and definitive zone) cells, not in definitive zone cells. Expression of 3 beta HSD was not detected in any cortical zone cells in midgestation human fetal adrenals. In rhesus monkey fetal adrenals, a similar pattern of P450scc and P450c17 expression was observed in the fetal and transitional zones. In the definitive zone cells of rhesu...
133 citations
01 Jan 1993
TL;DR: The data suggest that early in gestation, cortisol is not produced by the human fetal adrenal cortex in vivo (because it does not express 3 beta HSD), whereas androgen production occurs in the transitional and fetal zones (which express P450scc and P450c17).
Abstract: We examined the in situ localization of key steroidogenic enzymes in adrenal gland sections from midgestation (17-24 weeks) human fetuses and late gestation (130-142 days; term = 165 days) rhesus monkey fetuses. The rhesus monkey fetal adrenals were used as a model for the late gestation human fetal adrenal. The enzymes examined were cytochrome P450 cholesterol side-chain cleavage (P45Oscc), cytochrome P450 17ol-hydroxylase/l7,20-lyase (P45Oc17), and 3fl-hydroxysteroid dehydrogenase/isomerase (BPHSD). In human fetal adrenals, P45Oscc and P45Oc17 proteins and mRNAs were detected only in fetal zone (innermost cortical zone) and transitional zone (between the fetal and definitive zone) cells, not in definitive zone cells. Expression of 3PHSD was not detected in any cortical zone cells in midgestation human fetal adrenals. In rhesus monkey fetal adrenals, a similar pattern of P45Oscc and P45Oc17 expression was observed in the fetal and transitional zones. In the definitive zone cells of rhesus monkey fetal adrenals, expression of both P45Oscc and 3pHSD was detected. In addition, low levels of 3PHSD expression could be detected in some transitional zone cells. P45Oc17 expression was lacking in definitive zone cells from rhesus monkey fetal adrenals. These data suggest that early in gestation, cortisol is not produced by the human fetal adrenal cortex in vivo (because it does not express 3PHSD), whereas androgen production occurs in the transitional and fetal zones (which express P45Oscc and P45Oc17). Later in gestation, the definitive zone may produce mineralocorticoids (because it expresses P45Oscc and 3PHSD, but lacks P45Oc17), and the transitional zone may produce glucocorticoids (it expresses P45Oscc, P45Oc17, and 3flHSD), whereas the fetal zone continues to produce androgens. Thus, late in gestation the functional zonation of the human fetal adrenal cortex may be similar to that of the adult, with the definitive zone being analogous to the nascent zona glomerulosa, the transitional zone analogous to the zona fasciculata, and the fetal zone analogous to the zona reticularis. (J Clin
131 citations
TL;DR: The hypothesis that IGF-II may act as a mediator, in concert with bFGF and possibly EGF, of the tropic action of ACTH in regulating the rapid growth of the human fetal adrenal cortex during midgestation is supported.
Abstract: Polypeptide growth factors may play an important role in the regulation of human fetal adrenal cortical growth by mediating the tropic actions of ACTH. The abundance of mRNA encoding insulin-like growth factor-II (IGF-II) is high in the human fetal adrenal gland and is stimulated by ACTH in cultured fetal adrenal cortical cells. Therefore, we studied the mitogenic action, regulation, and localization of IGF-II and a closely related peptide, IGF-I, in primary cultures of human fetal adrenal cortical cells and whole human fetal adrenal glands. Recombinant human IGF-I and IGF-II stimulated proliferation of fetal adrenal cortical cells in a dose-dependent fashion (1-1000 ng/mL; 0.133-133 nM). At 1000 ng/mL (133 nM), both peptides increased cell number 1.8- to 2-fold. Combinations of IGF-I or -II (100 ng/mL; 13.3 nM) with basic fibroblast growth factor (bFGF; 0.1 ng/mL; 6 pM) or epidermal growth factor (EGF; 1.0 ng/mL; 0.17 nM) had a greater effect on proliferation than bFGF, EGF, or either of the IGFs alone, ...
127 citations
TL;DR: It is suggested that the female adrenal cortex is more responsive to ACTH than its male counterpart in terms of glucocorticoid production, and equivalent daily cortisol secretion rates are attained in men and women at the expense of greater ACTH release in men.
Abstract: = NS). There were no sex differences in the number of cortisol pulses We have investigated ACTH and cortisol secretion patterns in two or the calculated half-lives of ACTH and cortisol. ACTH and cortisol groups of five healthy adult male and female subjects. Plasma samples pulses were significantly concordant at a cortisol lag time of 10 min, as were obtained at lo-min intervals for 24 h, and pulsatile hormone demonstrated by probability analysis and cross-correlation with autorelease was analyzed by a multiparameter deconvolution technique. regressive modeling. Based on a significantly different regression interACTH secretion was greater in male than female subjects; the produc- cept of cortisol pulse height on ACTH pulse height in women than in tion rate per 24 h was 139 ? 7 pmol/L distribution volume in males, men (P < 0.001) and a higher ratio of cortisol to ACTH production and 89 & 11 pmol/L distribution volume in females (P = 0.007). Cortisol rates in women than in men (P = 0.013), we suggest that the female secretion did not differ significantly between sexes; in males, the 24-h adrenal cortex is more responsive to ACTH than its male counterpart secretion rate was 2807 ? 239 nmol/L distribution volume, and in in terms of glucocorticoid production. Consequently, equivalent daily females, it was 2970 ? 411 nmol/L distribution volume (P = NS). The cortisol secretion rates are attained in men and women at the expense number of ACTH secretory pulses per 24 h, as determined by decon- of greater ACTH release in men. (J Clin EndocrinoZ Metub 77: 234volution analysis, was 16.2 * 1.4 in males and 19.6 & 2.0 in females (P 240, 1993)
114 citations
TL;DR: Restoration of adrenal function after disappearance of AA indicates that a spontaneous remission of subclinical adrenocortical failure can occur, and AA, even if present initially in some subjects without clinical Addison's disease, can subsequently disappear.
Abstract: Idiopathic Addison's disease is a chronic organ-specific autoimmune disorder with a long subclinical period characterized only by the presence of adrenal autoantibodies (AA) with or without adrenal function failure. The aim of this longitudinal study was to evaluate the behavior of AA using, an indirect fluorescence method, and adrenal function in 20 AA-positive and 50 AA-negative patients screened by an investigation of a large population of organ-specific autoimmune disease patients without clinical Addison's disease. As controls, 100 normal age-matched subjects were tested only once. In the 20 AA-positive and 50 negative patients, AA and adrenal functional tests were evaluated every 4 months for 5 yr. The AA-positive patients were grouped into 5 adrenal functional stages, specifically: stage 0, normal adrenal function; stage 1, high PRA and low (or normal) aldosterone levels alone; stage 2, along with impaired cortisol response to ACTH, stage 3, along with increased ACTH levels; and stage 4, clinically overt Addison's disease. On the basis of the behavior of AA, the 20 positive patients were grouped as follows: group A, 11 patients with AA titer of 1:8 or higher at the first observation and persistently AA positive in subsequent observations, with titers ranging from 1:8 to 1:64; group B, 6 patients with initial AA titers of 1:8 or lower and AA disappearance in subsequent observations; and group C, 3 patients with AA titer of 1:32 or higher, undergoing corticosteroid therapy after the start of the study and showing AA disappearance in subsequent observations. With respect to adrenal function in group A, 2 patients initially in stage 1 and 1 patient initially in stage 2 did not progress to the upper stages, whereas 5 patients initially in stage 0 and 3 initially in stage 1 progressed subsequently to the upper stages, in 2 cases reaching overt clinical Addison's disease (stage 4). On the other hand, all of the patients of group B showed both a spontaneous disappearance of AA and recovery of adrenal function during the study span. Also, the 3 patients of group C showed disappearance of AA after corticosteroid therapy with recovery of adrenal function. None of the 50 patients who were initially AA negative became AA positive subsequently or showed impairment of adrenal function. We reached the following conclusions. 1) AA, even if present initially in some subjects without clinical Addison's disease, can subsequently disappear. 2) Restoration of adrenal function after disappearance of AA indicates that a spontaneous remission of subclinical adrenocortical failure can occur.(ABSTRACT TRUNCATED AT 400 WORDS)
106 citations
Journal Article•
TL;DR: The adrenal medulla was found to release numerous neuropeptides, in addition to catecholamines, in response to stimulation of the peripheral end of the right splanchnic nerve, which was carried out below behavioural threshold.
Abstract: Recent studies of adrenal function in conscious calves are reviewed. These have involved collecting the whole of the adrenal effluent blood from the right adrenal gland at intervals and, where necessary, prior functional hypophysectomy by destruction of the pituitary stalk under general halothane anaesthesia 3 d previously. The adrenal medulla was found to release numerous neuropeptides, in addition to catecholamines, in response to stimulation of the peripheral end of the right splanchnic nerve, which was carried out below behavioural threshold. Many of these responses were enhanced by stimulating intermittently at a relatively high frequency. Intra-aortic infusions of a relatively low dose of acetylcholine (4.5 nmol min-1 kg-1) elicited similar responses. In the adrenal cortex, agonists which either potentiated the steroidogenic response to ACTH or exerted a direct steroidogenic action included VIP, CGRP, CRF and ACh acting via muscarinic receptors. Stimulation of the peripheral end of the right splanchnic nerve strongly potentiated the steroidogenic response to ACTH and there is compelling evidence that the innervation normally plays an important part in cortisol secretion.
104 citations
TL;DR: It is demonstrated that part of the plasma renin and most of the adrenal renin are transgene determined and that the adrenalin is strongly activated in this hypertensive model of rats.
Abstract: The newly established rat strain TGR(mREN2)27 is a monogenetic model in hypertension research. Microinjecting the mouse Ren-2d renin gene caused it to become a stable part of the genome. The rats are characterized by fulminant hypertension, low plasma active renin, suppressed kidney renin, high plasma inactive renin, and high extrarenal transgene expression, most prominently in the adrenal cortex. Additionally, they exhibit significantly enhanced excretion of corticosteroids. Here we demonstrate that part of the plasma renin and most of the adrenal renin are transgene determined and that the adrenal renin is strongly activated. TGR(mREN2)27 adrenal cells may serve as a new tool to investigate the regulation and processing of Ren-2d-derived renin and its significance in hypertension and steroid metabolism. Adrenal renin in TGR(mREN2)27 is stimulated by 8-bromo-cAMP (8-Br-cAMP), angiotensin II (ANGII), and calcium. 8-Br-cAMP significantly stimulates active renin and prorenin release, as well as Ren-2d mRNA. Interestingly, within 60 min 8-Br-cAMP, ANGII, and calcimycin stimulate active renin, but not prorenin release. This indicates different intracellular pathways. An activated adrenal renin-angiotensin system in TGR (mREN2)27 as well as the lack of negative feedback on renin secretion by ANGII may be of pathophysiological significance in this hypertensive model.
TL;DR: The nucleotide sequence of DNA fragments generated by selective polymerase chain reaction amplification that span the four exons, the exon-intron boundaries, as well as the 5'-flanking region of each of the two 3 beta-HSD genes have been determined in three male pseudohermaphrodite 3 beta -HSD deficient patients from unrelated families.
Abstract: Congenital adrenal hyperplasia is the most frequent cause of adrenal insufficiency and ambiguous genitalia in newborn children. In contrast to congenital adrenal hyperplasia due to 21-hydroxylase and 11 beta-hydroxylase deficiencies, which impair steroid formation in the adrenal cortex, exclusively, classical 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) deficiency affects steroid biosynthesis in the gonads as well as in the adrenals. The structures of the highly homologous type I and II 3 beta-HSD genes have been analyzed in three male pseudohermaphrodite 3 beta-HSD deficient patients from unrelated families in order to elucidate the molecular basis of classical 3 beta-HSD deficiency from patients exhibiting various degrees of severity of salt losing. The nucleotide sequence of DNA fragments generated by selective polymerase chain reaction amplification that span the four exons, the exon-intron boundaries, as well as the 5'-flanking region of each of the two 3 beta-HSD genes have been determined in th...
TL;DR: Glutathione transferase pi exhibited a more general distribution and could be observed in epithelia of the respiratory, gastrointestinal and urinary tracts, in all endocrine cells investigated, and also in the exocrine glands of prostate, in smooth muscle, adipocytes, blood vessel endothelium and placenta.
Abstract: The distribution of alpha and pi class glutathione transferases in autopsy and biopsy samples of normal human tissues was investigated by immunohistochemistry. The class alpha glutathione transferases exhibited restricted distribution. Intensive staining was visible in all hepatocytes, in kidney proximal tubular cells, in the zona reticularis of adrenal cortex and in Leydig cells of testis. Staining of lesser intensity could also be observed in the gastrointestinal epithelium, exocrine pancreas and some bile and pancreas ducts. In colon and gall bladder only nuclei were stained, but in the other tissues both nuclei and cytoplasm contained alpha class glutathione transferases. Glutathione transferase pi exhibited a more general distribution and could be observed in epithelia of the respiratory, gastrointestinal and urinary tracts, in all endocrine cells investigated, and also in the exocrine glands of prostate, in smooth muscle, adipocytes, blood vessel endothelium and placenta. It was also visible in the Schwann cells of peripheral nerves and in the choroid plexus. In gall bladder and colon only nuclei were stained, while in the intrahepatic bile ducts only cytoplasm was stained. All other positive cells exhibited glutathione transferase pi in both nuclei and cytoplasm.
TL;DR: Tetrandrine affects with a similar potency aldosterone production, calcium influx, and T-type calcium channel activity, which strongly suggests a role for these channels in calcium signaling and control of steroidogenesis in adrenal glomerulosa cells.
Abstract: Tetrandrine, an alkaloid extracted from a Chinese medicinal herb traditionally used in hypertension treatment, inhibited aldosterone production induced in bovine adrenal glomerulosa cells by either potassium ion, angiotensin II, or ACTH in a concentration-dependent manner (IC50 = 10 microM). The inhibition of the response to potassium by tetrandrine had a pattern very similar to that of nickel, a blocker of T-type calcium channels. In addition, tetrandrine prevented calcium influx induced by potassium or angiotensin II without affecting the calcium release phase stimulated by the hormone. The effect of tetrandrine on voltage-activated barium currents was investigated using the whole cell configuration of the patch clamp technique. T-type currents were isolated by recording the slowly deactivating currents elicited during repolarization of the cell to -65 mV after various depolarizing pulses. These currents were blocked by micromolar concentrations of the drug. The voltage sensitivity of channel activation was not affected by tetrandrine; nevertheless, the drug significantly slowed the deactivation of the current. The action of tetrandrine did not require the activation of the channel. Tetrandrine also affected L-type currents, as assessed after inactivating T channels for 100 msec, but at higher concentrations of the drug. Thus, tetrandrine affects with a similar potency aldosterone production, calcium influx, and T-type calcium channel activity. This finding strongly suggests a role for these channels in calcium signaling and control of steroidogenesis in adrenal glomerulosa cells.
TL;DR: The present data suggest that 5-HT-evoked aldosterone secretion involves the activation of 4-HT4 receptors, and Zacopride was 100 times more potent in stimulating ald testosterone than cortisol release.
Abstract: We have recently shown that serotonin (5-HT) stimulates cortisol secretion from human adrenocortical tissue in vitro through activation of 5-HT4 receptors. The aim of the present study was to investigate the effect of the 5-HT4 agonist racemic zacopride on aldosterone secretion from the human adrenal gland in vivo and in vitro. In vivo studies were conducted on 28 healthy volunteers pretreated with dexamethasone. The subjects received a single oral dose of placebo, 10 micrograms zacopride, or 400 micrograms zacopride. Plasma aldosterone levels increased significantly within 90 min after the administration of 400 micrograms zacopride, remained elevated for 60 min, and gradually returned to the baseline within 180 min. In contrast, the administration of 10 micrograms zacopride or placebo did not modify the aldosterone concentration. No significant changes were observed in renin, ACTH, or cortisol levels. In vitro studies were conducted on perifused human adrenocortical slices. Administration of 20-min pulse...
TL;DR: Significantly higher basal HPA activity in the old dogs was indicated by their higher resting plasma concentrations of ACTH, alpha MSH, and cortisol over a 6-week period and higher cortisol excretion in 24-h urine, suggesting chronic hyperadrenocorticotropism.
Abstract: The effects of aging on the regulation of the hypothalamus-pituitary-adrenocortical (HPA) system of the dog were investigated. For this purpose, we compared 11 healthy dogs, 11-14 yr old, with 14 young mature dogs, 18-24 months of age. Significantly higher basal HPA activity in the old dogs was indicated by their higher resting plasma concentrations of ACTH, alpha MSH, and cortisol over a 6-week period and higher cortisol excretion in 24-h urine. After stress by immobilization as well as by light electric foot shocks and after i.v. administration of 1 microgram/kg CRH, the old dogs had higher peak levels of ACTH and cortisol, but not of alpha MSH. The areas under the curve, corrected for the basal levels, for ACTH and cortisol after these challenges were also greater in the old dogs. The half-times to reach a 50% increment and a 50% decrement in the time-concentration curves of ACTH and cortisol were similar in old and young dogs. There were no differences between the old and young dogs in their response to i.v. administration of 0.01 mg/kg dexamethasone. The clearance of [14C]cortisol from plasma, as calculated in a two-compartment model, was significantly reduced in aged dogs. In the old dogs, the stress- and CRH-induced cortisol peaks were relatively higher than those of ACTH, and their adrenals weighed significantly more, suggesting chronic hyperadrenocorticotropism. Aging had a markedly different effect on the two types of corticosteroid receptors in brain and pituitary. The binding capacity of type II or glucocorticoid receptors (GRs) in the old dogs was unchanged compared with that in the young dogs in all investigated brain structures except the anterior pituitary, in which the number of GRs was increased up to 170%. Type I or mineralocorticoid receptor (MR)-binding capacity was largely decreased in the brain of old dogs. The MR levels in old dogs, expressed as a percentage of the corresponding levels in young dogs, were 34% in the dorsal hippocampus, 58% in the ventral hippocampus, 37% in the septum, and 54% in the hypothalamus. In the anterior pituitary, MR capacity was unchanged. There was no difference between Kd values of MR and GR binding in young and old dogs. We conclude that these aged dogs had elevated basal HPA activity, characterized by increased levels of basal ACTH and cortisol in plasma and of urinary cortisol excretion and by hyperreactivity of ACTH and cortisol secretion in response to challenge by stress or CRH.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: These patients represent the first cases of ACTH-independent macronodular adrenal hyperplasia occurring in two generations of one family and illustrate the expanding clinical spectrum of Cushing's syndrome.
Abstract: Familial Cushing's syndrome is rare, and when it occurs, it is usually associated with primary micronodular dysplasia. We report two cases, a mother and daughter, who each presented with clinical features of Cushing's syndrome at age 38 yr and were found to have ACTH-independent macronodular adrenal hyperplasia. In each case, bilateral adrenalectomy revealed the massively thickened adrenal cortex with nodules up to 1.3 cm in diameter and hyperplasia between nodules. Dynamic testing showed no suppression of free cortisol with high dose dexamethasone and no stimulation of 17-hydroxycorticosteroids with metyrapone. Two samples of serum obtained preoperatively from one patient that showed ACTH immunoreactivity of 4.6 and less than 2.2 pmol/L, respectively, each showed less than 2.2 pmol/L ACTH bioactivity. The lack of suppression with high dose dexamethasone, lack of stimulation with metyrapone, and low levels of ACTH immunoreactivity and bioactivity suggest that the bilateral hyperplasia was not dependent upon ACTH. These patients represent the first cases of ACTH-independent macronodular adrenal hyperplasia occurring in two generations of one family and illustrate the expanding clinical spectrum of Cushing's syndrome.
TL;DR: Future investigations will be important to understand the relative role of the individual regulators in the physiological control of adrenal sensitivity to AII, and how activation of various intracellular messenger systems results in changes in activity of the enzymes of the aldosterone biosynthetic pathway.
TL;DR: The results provide the first evidence for the localization of NT-3-ir and indicate its presence in various peripheral organs and large sensory neurons, concluding thatNT-3 may function outside the nervous system in addition to a neurotrophic role within large sensory neuron.
TL;DR: It was concluded that TRH is an inhibitor of glucocorticoid secretion in rats, which electively impairs the late steps of B synthesis without affecting the earlier steps, including the rate-limiting one of this process.
Abstract: The bolus iv administration of TRH dose-dependently decreased ACTH-enhanced plasma corticosterone (B) concentration in rats, without affecting the basal one. The effects of TRH on steroid secretion of dispersed rat inner adrenocortical cells were investigated by HPLC. TRH significantly decreased both basal and ACTH-stimulated post-11-deoxycorticosterone (DOC) secretion (i.e. 18-hydroxy-DOC and B) and concomitantly raised DOC and progesterone release, so that the total postpregnenolone yield of our preparations was unaffected. TRH did not alter either basal or ACTH-stimulated pregnenolone production by isolated rat adrenocortical cells. It was concluded that TRH is an inhibitor of glucocorticoid secretion in rats, which electively impairs the late steps of B synthesis (i.e. 11- and 18-hydroxylation) without affecting the earlier steps, including the rate-limiting one of this process.
TL;DR: The results indicate that these proteins are made in response to calcium- or calcium/phosphoinositide-dependent mechanisms as well as by cAMP, and may be the proteins whose synthesis is crucial to acute control of steroidogenesis.
Abstract: Protein synthesis by bovine adrenal glomerulosa and fasciculata cells in response to various modulators of steroid synthesis was examined using [35S]methionine labeling and two-dimensional gel electrophoresis. Both cell types responded to steroidogenic stimuli with rapid changes in a family of 28- to 30-kilodalton (kDa) proteins similar to those described in rat fasciculata by Epstein and Orme-Johnson. In glomerulosa, angiotensin-II (AII), potassium, and (Bu)2cAMP stimulated the appearance of two 28.5-kDa proteins (no. 3 and 4) with pI values of 6.44 and 6.33 and decreased labeling of two other 28.5-kDa proteins (no. 1 and 2) with pI values of 6.9 and 6.59. The rank order of potency on aldosterone synthesis and that on proteins 1-4 were the same: (Bu)2cAMP > AII > potassium. Atrial natriuretic peptide blocked the effects of AII on all four proteins and on aldosterone synthesis. Adrenal secretagogues also affected labeling of four slightly larger (30 kDa) proteins (no. 5-8). Corresponding proteins in each quartet are separated by the same difference in isoelectric points. These eight proteins may represent a core protein systematically modified in a number of ways. Aldosterone synthesis in glomerulosa, like glucocorticoid synthesis in fasciculata, requires ongoing protein synthesis. The 28- to 30-kDa proteins increased by steroidogenic stimuli in both cells and decreased by atrial natriuretic peptide in glomerulosa may be the proteins whose synthesis is crucial to acute control of steroidogenesis. Our results indicate that these proteins are made in response to calcium- or calcium/phosphoinositide-dependent mechanisms as well as by cAMP.
TL;DR: PD 132301-2 or one of its metabolites has potent adrenocorticolytic properties and limited hepatotoxic properties by mechanism(s) that are likely independent of systemic ACAT inhibition.
TL;DR: In this paper, the authors studied steroidogenesis in nine cases of adrenocortical malignancy by analyzing biochemical enzyme activities and in situ hybridization of steroidogenic enzymes in carcinoma tissues.
TL;DR: In patch clamp recordings from bovine adrenal zona fasciculata cells, a novel cholera toxin-sensitive K+ current (IAC) is identified, which is potently inhibited by both ACTH and AII with respective EC50 values of 4.5 and 145 pM.
TL;DR: This is the first description of estradiol stimulation of cortisol production by cultured adrenal cells in ACTH-independent Cushing's syndrome and an adrenal-stimulating immunoglobulin is unlikely to be the cause of adrenal hyperfunction in this case.
Abstract: Adrenal glands from a patient with ACTH-independent Cushing's syndrome, whose symptoms worsened during pregnancy and oral contraceptive use, were cultured in different concentrations of estradiol. Estradiol stimulated cortisol secretion in a dose-response manner in the absence of ACTH. Since immunoglobulins G from this patient did not stimulate corticosterone production in a mouse adrenal bioassay, an adrenal-stimulating immunoglobulin is unlikely to be the cause of adrenal hyperfunction in this case. This is the first description of estradiol stimulation of cortisol production by cultured adrenal cells in ACTH-independent Cushing's syndrome.
TL;DR: The presence of HCA II and I in the zona glomerulosa cells may be linked to regulation of the biosynthesis or secretion of mineralocorticoids.
Abstract: Human carbonic anhydrase isoenzymes I and II (HCA I and II) were purified from human erythrocytes by inhibitor affinity chromatography and ion-exchange chromatography. These isoenzymes were then located in the human adrenal gland using specific polyclonal antisera raised in rabbits and specific detection by immunohistochemical techniques. Both HCA II and I were located in the zona glomerulosa cells, although the staining for HCA I was faint. The cells of the zona fasciculata and the zona reticularis failed to stain with either antiserum. Control stainings with preimmune or anti-HCA VI sera were negative. The presence of HCA II and I in the zona glomerulosa cells may be linked to regulation of the biosynthesis or secretion of mineralocorticoids.
TL;DR: A role for NO derived from L-arginine in the regulation of basal levels of adrenal vascular tone in the rat isolated adrenal gland preparation is suggested, but an obligatory role is not suggested in either the vascular or steroidogenic response to ACTH stimulation.
Abstract: The present studies were designed to investigate the role of nitric oxide (NO) in the regulation of adrenocortical function, using the intact rat adrenal gland in situ, perfused with medium (Hank's balanced salt solution) containing a range of concentrations of L-arginine, the substrate for NO production. In addition, the effects of NG-nitro-L-arginine methylester (L-NAME), an inhibitor of NO production, were investigated. Results showed that L-arginine caused a dose-dependent increase in the flow rate of the perfusion medium through the adrenal gland. This effect was specific, as neither D-arginine nor L-lysine had an effect. The presence of L-NAME (5 mmol/l) in perfusion medium containing L-arginine caused a decrease in flow rate to levels in the absence of L-arginine. In the presence of concentrations of L-arginine up to 500 mumol/l, corticosterone secretion rates were also stimulated in a dose-dependent manner. Further studies, investigating the effect of L-arginine on the response to ACTH(1-24) stimulation, found that the percentage increase in flow rate, aldosterone secretion and corticosterone secretion caused by ACTH were not significantly different using media containing 230 mumol L-arginine/l or in the absence of L-arginine. These results suggest a role for NO derived from L-arginine in the regulation of basal levels of adrenal vascular tone in the rat isolated adrenal gland preparation. They do not suggest an obligatory role for NO in either the vascular or steroidogenic response to ACTH stimulation.
TL;DR: The related ACTH and melanocyte-stimulating hormone (MSH) receptors control adrenal steroidogenesis and pigmentation in response to an overlapping set of peptides derived from the proopiomelanocortin molecule.
Abstract: The related ACTH and melanocyte-stimulating hormone (MSH) receptors control adrenal steroidogenesis and pigmentation in response to an overlapping set of peptides derived from the proopiomelanocortin (POMC) molecule. The recent cloning of these receptors has already opened up a new understanding of their role in normal and pathologic functioning of the adrenal cortex, and of the process of pigmentation. The murine MSH receptor maps to a genetic locus called extension, a locus known since early in this century to control the relative amounts of the two major types of melanins: eumelanin and phaeomelanin. The highly variable pigmentation phenotypes resulting from different extension locus alleles are caused by structural mutations in the MSH receptor that alter the degree of its signal-transducing capacity. A mutation in the ACTH receptor in a patient with ACTH resistance has also recently been reported. It is likely that the etiology of this rare disease includes mutations that affect the functioning of the ACTH receptor.
TL;DR: Evidence is provided that a separate AS plays a significant role in modulating aldosterone secretion in rodents and changes in AS and 11 beta-OHase mRNA levels with experimental maneuvers known to stimulate or suppress ald testosterone secretion are compared.
Abstract: Recent evidence suggests that an aldosterone synthase (AS) separate from the 11 beta-hydroxylase (11 beta-OHase) mediates the final step(s) in aldosterone synthesis in the rat. We have compared changes in AS and 11 beta-OHase mRNA levels with experimental maneuvers known to stimulate or suppress aldosterone secretion. In Exp 1, male rats were fed regular rat chow (group 1), a low sodium, high potassium diet (group 2), or a high sodium, low potassium diet (group 3). Northern analysis of adrenal capsular (zona glomerulosa) and decapsulated adrenal core (fasciculata-reticularis) tissues was performed with specific oligonucleotide probes for AS and 11 beta-OHase mRNAs, normalized with a cDNA probe for 18S ribosomal RNA (rRNA). There was a marked increase in capsular AS mRNA in group 2 rats compared to levels in group 1 (P < 0.0001) and group 3 (P < 0.0001) rats. Capsular As mRNA decreased (P < 0.05) in group 3 compared to that in group 1 rats. Adrenal core AS mRNA levels were quite low with all three diets. I...
TL;DR: The hypothesis that adrenocortical maturation occurs prematurely, augmenting adrenal responsiveness to ACTH after exposure to long-term hypoxemia is not supported, and the ability of the fetus to respond to an ACTH challenge is blunted.
Abstract: This study tested the hypothesis that in the fetus long-term hypoxemia induces premature adrenocortical maturation and augments adrenal responsiveness to adrenocorticotropin hormone (ACTH). Pregnant ewes were exposed to high altitude (3,820 m) from 30 to 120 days gestation, when surgery was performed. Maternal arterial pressure of O2 (PaO2) was maintained at approximately 60 Torr by N2 infusion through a tracheal catheter. Fetal PaO2 was significantly lower in the hypoxemic (21 +/- 0.2 Torr) vs. normoxic (26 +/- 0.4 Torr) fetuses (P < 0.01). Between 125 and 140 days, basal ACTH and cortisol concentrations were similar in both groups. To assess changes in adrenal responsiveness, we challenged the fetuses with ACTH (100 ng/kg body wt, iv bolus) at 126 and 136 days. At 126 days, after ACTH challenge, fetal plasma ACTH peaked at similar values (275 +/- 43 and 250 +/- 26 pg/ml) in normoxic and hypoxemic fetuses, respectively. Plasma cortisol subsequently increased to 84 +/- 8 and 44 +/- 6 ng/ml in these groups. At 136 days, after ACTH challenge, plasma ACTH peaked at 379 +/- 57 and 336 +/- 21 pg/ml in normoxic and hypoxemic fetuses, respectively. Although plasma cortisol concentration in normoxic fetuses increased to 180 +/- 21 ng/ml, levels in hypoxemic fetuses only reached 62 +/- 12 ng/ml (P < 0.05 compared with normoxic). Catecholamine concentrations were not significantly different between the two groups. These data do not support the hypothesis that adrenocortical maturation occurs prematurely, augmenting adrenal responsiveness to ACTH after exposure to long-term hypoxemia. Rather, the ability of the fetus to respond to an ACTH challenge is blunted.