Showing papers on "Adrenal cortex published in 1983"

Salivary Cortisol: A Better Measure of Adrenal Cortical Function than Serum Cortisol

Abstract: Salivary cortisol concentration was found to be directly proportional to the serum unbound cortisol concentration both in normal men and women and in women with elevated cortisol-binding globulin (CBG). The correlation was excellent in dynamic tests of adrenal function (dexamethasone suppression, ACTH stimulation), in normals and patients with adrenal insufficiency, in tests of circadian variation and randomly collected samples. Women in the third trimester of normal pregnancy exhibited elevated salivary cortisol throughout the day. The relationship between salivary and serum total cortisol concentration was markedly non-linear with a more rapid increase in salivary concentration once the serum CBG was saturated. The rate of equilibrium of cortisol between blood and saliva was very fast, being much less than 5 minutes. These data, combined with a simple, stress-free, non-invasive collection procedure, lead us to suggest that salivary cortisol is a more appropriate measure for the clinical assessment of adrenocortical function than is serum cortisol.

Regulation of intramitochondrial cholesterol transfer to side-chain cleavage cytochrome P-450 in rat adrenal gland.

Abstract: Rat adrenal mitochondria accumulated cholesterol during ether stress in vivo when side-chain cleavage was inhibited by aminoglutethimide (control = 14.6 vs. aminoglutethimide = 26.5 micrograms of cholesterol per mg of protein). This accumulation was insensitive to simultaneous administration of cycloheximide (24.2 micrograms/mg), but side chain cleavage in the mitochondria was greatly decreased. Outer and inner mitochondrial membrane fractions were separated by discontinuous Ficoll gradient centrifugation. Quantitation of marker enzymes for inner, outer, and microsomal enzymes indicated that outer membranes contained less than 5% inner membranes. The inner membrane fraction contained less than 7% outer membrane and included 90% of mitochondrial cytochrome P-450. Electron microscopy revealed outer membranes as circular intact ghosts, whereas inner membranes were largely intact and retained vesicular structure typical of intact adrenal cortex mitochondria. Administration of aminoglutethimide effected a 2-fold increase in inner membrane cholesterol (9.4 vs. 20.1 micrograms/mg) but simultaneous administration of cycloheximide completely blocked this increase (10.9 micrograms/mg). We conclude that: (i) in the presence of aminoglutethimide, stress stimulates accumulation of cholesterol in the inner membrane of adrenal mitochondria; and (ii) transfer of cholesterol from outer to inner membranes requires a cycloheximide-sensitive agent.

Apolipoprotein E synthesis in human kidney, adrenal gland, and liver

Abstract: Human tissues were incubated in vitro with radiolabeled amino acids to determine whether plasma apolipoproteins are synthesized in human kidney. Subsequently, tissue extracts were screened with antisera directed against apolipoprotein E (apo E), apolipoprotein B (apo B), apolipoprotein AI (apo AI), and bulk apolipoproteins of high density lipoprotein (HDL). Newly synthesized apo E, but not apo AI or apo B, was identified in kidney and adrenal cortex. Estimates of relative rates of apo E synthesis in vitro suggest that a substantial portion of adrenal and kidney protein synthesis is committed to apo E synthesis. The relative rate of apo E synthesis was 4-6 times greater in kidney cortex than in kidney medulla. Analysis of immunoreactive apo E showed that kidney and adrenal apo E species have the same electrophoretic mobility in NaDodSO4/polyacrylamide gels as does plasma apo E. Further characterization by high resolution two-dimensional gel analysis indicated that the isoforms of newly synthesized kidney and adrenal apo E correspond to specific isoforms of plasma apo E. These findings suggest that apolipoproteins arising from peripheral tissues may play an important role in lipid transport and metabolism.

Regulation by ACTH of steroid hormone biosynthesis in the adrenal cortex

Abstract: In this article, current knowledge about the mechanism of action of ACTH will be reviewed. Emphasis will be placed on events which occur subsequent to binding of ACTH to its receptor, stimulation o...

Cholesterol side-chain cleavage in the rat adrenal cortex: isolation of a cycloheximide-sensitive activator peptide.

Abstract: A cytosolic peptide activator (Mr approximately equal to 2,200) of cholesterol side-chain cleavage in the adrenal cortex has been isolated from normal corticotropin-treated rats and from rats implanted with the MtT/F4 corticotropin-secreting pituitary tumor. The isolation techniques were those common to peptide hormone purification, including tissue extraction into a highly acidic medium, gel filtration, and reverse-phase HPLC. The amino acid composition has been determined on acid hydrolysates. The activity of this adrenal peptide is acutely increased in hypophysectomized animals treated with corticotropin, and this increase is blocked by cycloheximide. The addition of activator peptide to adrenal mitochondrial preparations results in a rapid stimulation of pregnenolone formation that is dependent on activator concentration and a source of NADPH. In the absence of NADPH, addition of activator peptide to adrenal mitochondria increases the rate of cholesterol association with side-chain cleavage cytochrome P-450. The peptide therefore exhibits properties that are believed to characterize the hypothetical corticotropin-dependent labile activator of adrenal steroidogenesis.

The thymus-adrenal connection: thymosin has corticotropin-releasing activity in primates

Abstract: Endotoxin-free thymosin fraction 5 elevated corticotropin, beta-endorphin, and cortisol in a dose- and time-dependent fashion when administered intravenously to prepubertal cynomolgus monkeys. Two synthetic component peptides of thymosin fraction 5 had no acute effects on pituitary function, suggesting that some other peptides in thymosin fraction 5 were responsible for its corticotropin-releasing activity. In agreement with these observations, total thymectomy of juvenile macaques was associated with decreases in plasma cortisol, corticotropin, and beta-endorphin. These findings indicate that the prepubertal primate thymus contains corticotropin-releasing activity that may contribute to a physiological immunoregulatory circuit between the developing immunological and pituitary-adrenal systems.

Identification of pro-opiomelanocortin-derived peptides in the human adrenal medulla

Abstract: Extracts from adult human adrenals contained high concentrations of immunoreactive beta-endorphin and alpha-melanotropin. Lower quantities of immunoreactive adrenocorticotropic hormone could also be detected. Distribution studies showed the presence of pro-opiomelanocortin fragments in the adrenal medulla. No alpha-melanotropin, beta-endorphin, or adrenocorticotropic hormone could be found in adrenal extracts from several other mammalian species. Analysis of the beta-endorphin-like immunoreactivity using region specific radioimmunoassays interfacing with gel filtration and reverse-phase high-performance liquid chromatography showed the majority of the beta-endorphin-like material to exist as nonacetylated beta-endorphin-(1-31) with a small percentage of lipotropin-sized molecules. The alpha-melanotropin-like immunoreactivity cochromatographed on gel filtration and reverse-phase high-performance liquid chromatography with desacetyl alpha-melanotropin. The data suggest that pro-opiomelanocortin is expressed in the adrenal medulla of humans but is not detectable in the adrenal glands of many other mammalian species.

Sex differences in adrenocortical structure and function

Abstract: The cytological aspects of sexual dimorphism in the rat adrenal cortex and its relationship to the gonads have been investigated. The adrenal glands of mature female rats were heavier than those of males, and morphometry showed that this was almost exclusively due to conspicuous differences in the volume of cells of the zona fasciculata (ZF) and zona reticularis (ZR). Stereology demonstrated that the volume of the mitochondrial and lipid droplet compartments, as well as the surface area per cell of mitochondrial cristae and smooth endoplasmic reticulum tubules, were markedly higher in the ZF and ZR cells of female animals. Orchiectomy increased and ovariectomy decreased the adrenal weight, by eliciting hypertrophy and atrophy, respectively, of ZF and ZR cells; these effects of gonadectomy were reversed by the appropriate gonadal hormone replacement. It is suggested that the sexual dimorphism of the rat adrenal cortex may depend upon the inhibitory action of testosterone and the stimulatory effect of estradiol on the hypothalamo-hypophyseal-adrenal axis.

Adrenal cortex of fetal lamb: changes after hypophysectomy and effects of Synacthen on cytoarchitecture and secretory activity.

Abstract: The effects of hypophysectomy on the cell population of the adrenal cortex has been examined with light and electron microscopy. The sensitivity of the adrenal cortical cells to exogenous ACTH in both normal and hypophysectomized fetuses has been investigated by comparing plasma cortisol concentrations with structural changes in the adrenal cortex. Hypophysectomy was carried out at about 100 d and the subsequent analysis was made at about 135 d on fetuses catheterized at least 6 d earlier. The zona fasciculata of intact fetuses contained about 25% mature and 75% immature cells at 130-136 d. After hypophysectomy this zone contained a uniform population of immature cells and no mature cells; there was a significant reduction in both adrenal weight and cortical thickness. The zona glomerulosa was unaffected by hypophysectomy. The infusion of Synacthen 0 . 25 mg/d I.V. for 48 h did not affect the zona glomerulosa but resulted in a 2-fold increase in the thickness of the zona fasciculata in hypophysectomized and intact fetuses. This cortical growth was due to both hypertrophy and hyperplasia. All the cells in the zona fasciculata were mature following Synacthen treatment in both groups. The most striking difference between the secretory response of the adrenal cortex to Synacthen in the two groups was found within 3-6 h of the onset of infusion. Within this period there was a significant increment in the plasma cortisol concentration in the intact fetuses while no response was observed in the hypophysectomized animals. After 12 h infusion by contrast, a steadily rising response was observed in both groups. There was a significant correlation between the final plasma cortisol concentration and both the adrenal weight and cortical thickness after 48 h treatment. The increased sensitivity of the adrenal cortex to exogenous ACTH as term approaches in the sheep is considered to be dependent upon the increasing proportion of mature zona fasciculata cells within the adrenal cortex.

Characteristics and regulation of angiotensin II receptors in pituitary, circumventricular organs and kidney.

Abstract: Receptors for angiotensin II (AII) have been identified and characterized in many AII-responsive tissues. Those in the adrenal zona glomerulosa and vascular smooth muscle undergo dynamic regulation which appears to be mediated by changes in circulating AII, and is followed by parallel changes in sensitivity to AII.Pituitary AII receptors are mainly located in lactotrophs and corticotrophs, where they mediate specific actions of AII upon prolactin and ACTH secretion, acting in conjunction with other hypothalamic regulators. In contrast to adrenal and vascular AII receptors, those in the anterior pituitary are not affected by changes in salt balance or AII infusion.In the brain, AII receptors were increased in the subfornical organ during dehydration, but show no significant changes in the other circumventricular organs. The increase in subfornical organ receptors resembles the up-regulation of AII sites which occurs in the adrenal cortex during sodium deficiency, and could play a role in potentiating the d...

A possible role of "steroidogenic factor" in the corticoidogenic response to ACTH; Effect of ACTH, cycloheximide and aminoglutethimide on the content of cholesterol in the outer and inner mitochondrial membrane of rat adrenal cortex.

Abstract: The role of a "steriodogenic factor" in the corticoidogenic response to adrenocorticotropic hormone (ACTH) was studied in this experiment ACTH caused an accumulation of cholesterol within the adrenocortical mitochondria in rat after pretreatment with either cycloheximide (CH) or aminoglutethimide (AG) The cholesterol distribution in these cholesterol-rich mitochondria was examined by measuring the cholesterol concentrations in the outer and inner mitochondrial membranes In the case of pretreatment with CH, cholesterol was accumulated in the outer membrane and not in the inner membrane In contrast, in the case of pretreatment with AG, cholesterol was accumulated in the inner membrane and not in the outer membrane It could be concluded from the presented data that the function of a "steroidogenic factor" in the corticoidogenic response to ACTH might take place at the step of cholesterol translocation from the outer mitochondrial membrane to the inner membrane

Adrenal cortical function in homozygous familial hypercholesterolemia

Abstract: The biosynthesis of adrenal corticosteroids requires a supply of cholesterol that can be derived from both local synthesis and uptake of plasma lipoproteins. Recent studies have provided evidence that receptor-mediated uptake of low density lipoproteins provides an important source of cholesterol for corticosteroid synthesis by human adrenocortical cells that are grown in tissue culture. In the present study we have examined parameters of adrenocortical function in three patients with homozygous familial hypercholesterolemia (two receptor negative, one receptor defective) to assess whether a decreased number of LDL receptors, measured in vitro, influences in vivo corticosteroid production under basal conditions and in response to prolonged stimulation with ACTH. Basal adrenocortical function (assessed by the serum concentrations of cortisol and ACTH plus urinary excretion of 17 OHCS, 17 KS, and urine-free cortisol) was normal in all three patients. Stimulation with intravenous ACTH resulted in rapid increases in the serum concentrations of cortisol in all patients. Plateau concentrations of cortisol during prolonged ACTH stimulation were lower in the two receptor-negative patients (36 to 41 μg/dl) but all subjects had at least a threefold increase over basal values. Excretion of urine-free cortisol was reduced in both receptor-negative patients (33% to 36% of controls); this was paralleled by decreased excretion of 17 KS in both patients and of 17 OHCS in one patient. Urine-free cortisol excretion was reduced in the receptor-defective patient (57% of controls), but excretion of 17 OHCS and 17 KS was not. The results suggest that patients with homozygous familial hypercholesterolemia have a mild impairment in delivery of cholesterol to the adrenal cortex during maximal stimulation of corticosteroid production but that the disease does not impair corticosteroid synthesis in the basal state.

The distribution of cathepsin D in rat tissues determined by immunocytochemistry.

Abstract: The distribution of cathepsin D (CD) was surveyed in rat tissues by light microscopic immunocytochemistry. Although immunoreactive CD was detected in all tissues examined, there was a marked difference in the amount in the cytoplasm of different cell types of the same organ. In the retina large amounts of CD were present in the pigment epithelium, ganglion cells, and Muller cells. Moderate to large amounts of CD were also found in neuronal perikarya of the gastrointestinal tract and adrenal medulla; in macrophages in the lung, liver, and spleen; in some secretory cells of the submandibular and lacrimal glands; in parts of renal distal convoluted and collecting tubules; and in the surface transitional epithelium of the calyx, ureter, and urinary bladder. Other cells adjacent to cells containing large amounts of the enzyme had little or no detectable CD themselves. These included hepatocytes, the proximal tubular cells of the kidney, selected cells of the submandibular gland, cells of the zona glomerulosa of the adrenal cortex, and lymphocytes in lymphoid organs. The localization of CD indicates that its degradative effect is exerted preferentially in certain cell types and suggests that physiological influences on CD may have a variety of effects in different organs.

Nuclear magnetic resonance imaging of the adrenal gland: a preliminary report.

Abstract: Nuclear magnetic resonance (NMR) imaging characteristics of the normal and abnormal adrenal gland were evaluated and compared with findings on computed tomography (CT). Forty-two patients were examined: 36 had normal adrenal glands and 6 had adrenal disease (3 metastatic lesions, 1 pheochromocytoma, and 2 cortical hyperplasia). NMR clearly showed all 42 left adrenals (100%) and 36 right adrenals (86%). In some patients, it appeared to differentiate the adrenal cortex from the medulla. The ability of NMR to detect adrenal disease was similar to that of CT in 6 cases examined. CT demonstrated superior spatial resolution in most cases, but NMR provided superior soft-tissue contrast. Since NMR does not involve ionizing radiation and provides excellent soft-tissue differentiation without contrast material, it has advantages over CT and appears to be a promising modality for imaging of the adrenal gland.

Lys-γ3-Melanotropin Binds with High Affinity to the Rat Adrenal Cortex*

Abstract: Partially purified plasma membrane preparations from the inner zones of the rat adrenal exhibit a specific and high affinity for a pro-gamma MSH peptide, synthetic rat Lys-[125I-iodo-Tyr1] gamma 3MSH, that is time and temperature dependent, reversible, and saturable. Studies with demedullated adrenals indicate that at least part of this binding is to the adrenal cortex. Scatchard analysis reveals a single class of binding sites (101 fmol/mg membrane protein) for the radioactive ligand, with an apparent Kd of 0.74 nM. However, this may understate the receptor affinity for native pro-gamma MSH(s), because the binding capacity of Lys-gamma 3MSH is impaired somewhat by iodination. Lys-[125I-iodo-Tyr1] gamma 3MSH exhibits a 100-fold higher affinity for the binding site than ACTH-(1-24), but unlike ACTH, concentrations of Lys-gamma 3MSH up to 10 microM fail to stimulate membrane-associated adenylate cyclase activity. Guanylate cyclase in this subcellular fraction also is unresponsive to Lys-gamma 3MSH. Results obtained with crude membrane fractions from other rat tissues suggest that specific pro-gamma MSH binding may not be unique to the adrenal cortex.

Suppression of cultured bovine adrenocortical zona glomerulosa cell aldosterone synthesis by steroids and its prevention by antioxidants.

Abstract: Previous work suggested that autoregulation of adrenocortical function by steroids may be important in the development of different functional zones of the adrenal cortex, possibly through the generation of oxygen-derived free radicals after an interaction with cytochrome P-450s. The present experiments investigate the effects of pretreatment with various steroids on subsequent conversion of deoxycorticosterone (DOC) to aldosterone by primary cultures of bovine adrenocortical zona glomerulosa cells. The products of DOC metabolism, quantitated by high performance liquid chromatography, were aldosterone, 18-hydroxycorticosterone (18-OH B), 18-hydroxydeoxycorticos-terone (18-OH DOC), and corticosterone. Corticosterone was the major product formed (approximately 80%), whereas 18-OH B and 18-OH DOC were formed in equal amounts (approximately 10%) and aldosterone was formed in lesser amounts (1%). The maximal rate of production of aldosterone using DOC as precursor was twice the maximal rate using corticosteron...

Striated adrenocortical cells in cerebro-hepato-renal (Zellweger) syndrome

Abstract: Adrenal glands from eight patients with the cerebro-hepato-renal syndrome, a disease in which there are no morphologically demonstrable peroxisomes, were studied histologically; one of the eight was also examined ultrastructurally Seven of the eight demonstrated striated adrenocortical cells in the inner portion of the adrenal cortex Ultrastructural examination confirmed that the striated cells contained the lammellae and lamellar-lipid profiles of very long chain fatty acids-cholesterol esters that are characteristic of adreno-leukodystrophy This morphologic observation further emphasizes the common pathogenetic features of the cerebro-hepato-renal (Zellweger) syndrome and adreno-leukodystrophy

Dehydroepiandrosterone sulfotransferase localization in human adrenal glands: a light and electron microscopic study.

Abstract: Dehydroepiandrosterone sulfate is the major secretory product of the human adrenal cortex. The enzyme responsible for the sulfurylation, which has been isolated previously, possesses kinetic properties suggesting that it plays an important regulatory role in dehydroepiandrosterone sulfate secretion. In order to study the localization of the enzyme in the respective zones and cells of the cortex, an antibody to the pure enzyme was raised and the immunoglobulin G fraction employed in the peroxidase-antiperoxidase method. Staining was confined to the zona reticularis but was unevenly distributed throughout the cells. Electron microscopic examination of sections prepared from fresh adrenal tissue fixed in glutaraldehyde, revealed that the enzyme was predominantly clustered around lipid droplets. It is suggested that this may reflect an association of organelles, cholesterol being transported from lipid droplets to surrounding mitochondria, and pregnenolone then being converted to dehydroepiandrosterone in the...

Serum and growth factor requirements for proliferation of human adrenocortical cells in culture: Comparison with bovine adrenocortical cells

Abstract: Although bovine adrenocortical cells proliferate readily in cell culture, proliferation of fetal or adult human adrenocortical cells has been observed to be limited and preparation of pure proliferating cultures of human adrenocortical cells has not been reported. The growth requirements of fetal human definitive zone adrenocortical cells in culture were compared to the established requirements of bovine adrenocortical cells. The medium used was 1:1 Ham's F12 and Dulbecco's modified Eagle's medium supplemented with transferrin and insulin. Earlier experiments showed that human cells had a greater proliferative response to horse serum than to fetal bovine serum, whereas the opposite was true for bovine cells. When plated on fibronectin-coated dishes and exposed to varying concentrations of horse serum in the presence of 100 ng/ml fibroblast growth factor (FGF), increasing cell growth was observed up to a serum concentration of 50%. When 50% fetal bovine serum was used instead of horse serum proliferation was less. In contrast, bovine adrenocortical cells showed a maximal proliferative response to either fetal bovine serum or horse serum at 10%. Human adrenocortical cells thus have a very high requirement for serum; 50% is the highest level that may be practically used, but the shape of the dose-response curve suggests that this concentration is still suboptimal. Growth was less in the absence of FGF. Epidermal growth factor can partially substitute for FGF. No response to 100 nM placental lactogen was observed. Less growth was observed when dishes were not coated with fibronectin. The factors present in horse serum that are evidently needed in high amounts by human cells are unknown. Despite this lack of knowledge, use of 50% horse serum enabled long-term growth of human adrenocortical cells that are pure by the criterion of retraction in response to ACTH. Nonadrenocortical cells do not show a retraction response. Such long-term cultures may be useful in studies of long-term regulation of differentiated function, aging, and carcinogenesis.

Thymosin peptides and lymphokines do not directly stimulate adrenal corticosteroid production in vitro.

Abstract: There is developing evidence that certain thymosin peptides and lymphokines produce a transient increase in steroid hormones when introduced systemically. Conversely, the repressive effect of adrenocortical steroids on the immune system is well documented. In the present study, the direct effect of certain components of the immune system on steroid output by rat adrenal fasciculata cells was tested. With this system, there was no direct steroidogenic effect of either the partially purified thymosin fraction 5, or any of the purified peptide components tested (thymosin alpha 1, alpha 7, or beta 4). These peptides also did not synergize the cellular response to ACTH, nor did they induce cAMP production by a ACTH- and NaF-responsive adrenal membrane preparation. Supernatants from Con A-stimulated spleen cells, which were demonstrated to contain lymphokine activity, and partially purified mouse interferon were also without a significant direct or synergistic effect on steroidogenesis by adrenocortical cells. These results suggest that the steroidogenic response to these peptides observed in vivo may be mediated by the central nervous system.