Structural and functional characteristics of primary cell cultures derived from the adrenal gland tissue of neonatal mallard ducklings (Anas platyrhynchos)

Summary Primary cell cultures were prepared from the adrenal glands of one-day-old mallard ducklings (Anas platyrhynchos). The cells attached equally well to uncoated plastic and glass surfaces and on surfaces that had been coated with collagen. The phase of logarithmic growth occurred between the second and the fourth day, and the cells became confluent between the fifth and the sixth day. Staining with Sudan black B and toluidine blue and viewing fixed preparations by transmission electron microscopy indicated that the cultures consisted mostly of steroidogenic cells. A smaller population of chromaffin cells was also present. Scanning electron microscopy showed that most of the cells had long filopodia, and some cells had numerous surface blebs that were interpreted as exocytotic vesicles. When incubated in Krebs-Henseleit buffer containing 1–24 ACTH the cultured cells released three corticosteroids, namely, corticosterone, aldosterone and deoxycorticosterone. These responses occurred within 15 min of exposure to medium containing 1–24 ACTH and continued throughout a 60-min period of continuous stimulation. The minimally effective concentration of 1–24 ACTH was 0.078 ng per ml (0.0234 nM) and, as the concentration was increased up to 10 ng per ml (2.99 nM), the total output of each hormone during the 60-min incubation period increased significantly according to the following semi-logarithmic relationship: Y=a+b log X, where Y=the total output of hormone, X=the concentration of 1–24 ACTH in the medium, and a=the total output of hormone when the medium contained 1.0 ng of 1–24 ACTH per ml. The total outputs of each hormone in the presence of a maximally effective concentration of 1–24 ACTH, however, were low compared to the responses of similarly stimulated tissue slices taken from the neonatal duckling. It is concluded that most of the cells comprising the confluent cultures were derived from steroidogenic cells in the neonatal adrenal. These cells appeared to retain corticotropin receptors during the course of developing into confluent monolayers, but their diminished steroidogenic capacity to respond when stimulated maximally suggests that some generational changes may have occurred.This work was supported by grants to James Cronshaw and W.N. Holmes from the University of California Committee on Research and the National Science Foundation (DIR-8820923), Washington, DC, USA     

Release of aldosterone and catecholamines from the interrenal gland of Triturus carnifex in response to adrenocorticotropic hormone (ACTH) administration

The influence of adrenocorticotropic hormone (ACTH) on the interrenal gland of Triturus carnifex was investigated by in vivo administration of synthetic ACTH. The effects were evaluated by examination of the ultrastructural morphological and morphometrical features of the tissues as well as the circulating serum levels of aldosterone, noradrenaline (NA), and adrenaline (A). In June and November, ACTH administration increased aldosterone release (from 281.50 +/- 1.60 pg/ml in carrier-injected newts to 597.02 +/- 3.35 pg/ml in June; from 187.45 +/- 1.34 pg/ml in carrier-injected animals to 651.00 +/- 3.61 pg/ml in November). The steroidogenic cells showed clear signs of stimulation, together with a reduction of lipid content in June and an increase of lipid content in November. Moreover, ACTH administration decreased the mean total number of secretory vesicles in the chromaffin cells in June (from 7.73 +/- 0.60 granules/microm2 in carrier-injected animals to 5.91 +/- 0.40 granules/microm2) and November (from 7.78 +/- 0.75 granules/microm2 in carrier-injected newts to 4.87 +/- 0.40 granules/microm2). In June, however, when T. carnifex chromaffin cells contain almost exclusively NA granules (NA: 7.42 +/- 0.86 granules/microm2; A: 0.32 +/- 0.13 granules/microm2), ACTH decreased NA content (5.52 +/- 0.32 granules/microm2) increasing NA release (from 639.82 +/- 3.30 pg/ml in carrier-injected to 880.55 +/- 4.52 pg/ml). In November, when both catecholamines, NA (3.92 +/- 0.34 granules/microm2) and A (3.84 +/- 0.33 granules/microm2), are present in the chromaffin cells, ACTH administration reduced A content (1.02 +/- 0.20 granules/microm2), enhancing adrenaline secretion (from 681.30 +/- 3.62 pg/ml in carrier-injected newts to 1,335.73 +/- 9.03 pg/ml). The results of this study indicate that ACTH influences the steroidogenic tissue, eliciting aldosterone release. The effects on the chromaffin tissue, increase of NA or A secretion, according to the period of chromaffin cell functional cycle, may be direct and/or mediated through the increase of aldosterone release. Finally, the lack of an increase of A content in the chromaffin cells, or A serum level, following ACTH administration in June might suggest an independence of PNMT enzyme on corticosteroids.     

Effects of noradrenaline administration on the interrenal gland of the newt, Triturus carnifex: evidence of intra-adrenal paracrine interactions

The existence of paracrine control of steroidogenic activity by adrenochromaffin cells in Triturus carnifex was investigated by in vivo noradrenaline (NA) administration. The effects were evaluated by examination of the ultrastructural morphological and morphometrical features of the tissues as well as the serum levels of aldosterone, NA, and adrenaline (A). In March and July, NA administration increased aldosterone release (from 187.23 +/- 2.93 pg/ml to 878.31 +/- 6.13 pg/ml in March; from 314.60 +/- 1.34 pg/ml to 622.51 +/- 2.65 pg/ml in July) from steroidogenic cells. The cells showed clear signs of stimulation, as evidenced by a strong reduction of lipid content. Moreover, NA administration decreased the mean total number of secretory vesicles in the chromaffin cells in March (from 7.24 +/- 0.18 granules/micro2 to 5.57 +/- 1.88 granules/micro2) and July (from 7.74 +/- 0.74 granules/micro2 to 6.04 +/- 1.13 granules/micro2). In March, however, when T. carnifex chromaffin cells contain both catecholamines, NA (3.88 +/- 0.13 granules/micro2) and A (3.36 +/- 0.05 granules/micro2) in almost equal quantities, NA administration reduced A content (1.29 +/- 1.04 granules/micro2) in the chromaffin cells, enhancing adrenaline secretion (from 681.27 +/- 1.83 pg/ml to 1527.02 +/- 2.11 pg/ml). In July, when the chromaffin cells contain almost exclusively NA granules (NA: 7.42 +/- 0.86 granules/micro2; A: 0.32 +/- 0.13 granules/micro2), NA administration reduced the number of NA granules (5.45 +/- 1.10 granules/micro2), thereby increasing noradrenaline release from the chromaffin cells (from 640.19 +/- 1.65 pg/ml to 1217.0 +/- 1.14 pg/ml). The results of this study indicate that NA influences the steroidogenic cells, eliciting aldosterone release. Noradrenalin effects on the chromaffin cells, increase of NA or A secretion, according to the period of chromaffin cell functional cycle, may be direct and/or mediated through the steroidogenic cells. The existence of intra-adrenal paracrine interactions in T. carnifex is discussed.     

A two-step model for acetylcholine control of exocytosis via nicotinic receptors

The view that Ca²⁺ entry through voltage-dependent Ca²⁺ channels (VDCC) and through nicotinic receptors for acetylcholine (nAChRs) causes equal catecholamine release responses in chromaffin cells, was reinvestigated here using new protocols. We have made two-step experiments consisting in an ACh prepulse followed by a depolarizing pulse (DP). In voltage-clamped bovine chromaffin cells an ACh prepulse caused a slow-rate release but augmented 4.5-fold the much faster exocytotic response triggered by a subsequent depolarizing pulse (measured with capacitance and amperometry). If the ACh prepulse was given with mecamylamine or in low external Ca²⁺, the secretion increase disappeared. This suggests a two-step model for the effects of ACh: (1) meager Ca²⁺ entry through nAChRs mostly serves to keep loaded with vesicles the secretory machine; and (2) in this manner, the cell is prepared to respond with an explosive secretion of catecholamine upon depolarization and fast high Ca²⁺ entry through VDCC.     

Effects of cytochalasin D on the distribution of actin and ACTH-induced steroidogenesis in cultured embryonic adrenal gland cells from the Pekin duck (Anas platyrhynchos)

Cultured steroidogenic cells derived from the adrenal glands of duck embryos were used to study changes in the distribution of actin associated with the corticotropic responsiveness. Actin-containing components were identified by rhodamine-phalloidin staining. The actin in most of the unstimulated cells occurred as stress fibers that either ran parallel throughout the cell or were present as domains of parallel fibers at angles to one another. When incubated in Krebs-Henseleit buffer containing 1–24 ACTH, the cells released approximately equal amounts of corticosterone and aldosterone. Incubation of the cells in buffer containing cytochalasin D caused the cells to lose their stress fibers, and the actin became distributed at the periphery in what appeared to be fragments of stress fibers and clumps of fibrous material in the central cytoplasm. Although cytochalasin D did not affect the basal output of corticosterone and aldosterone, the 1–24 ACTH-induced rates of both hormones were suppressed significantly. After the cells had been washed in unadulterated buffer, the normal distribution of actin stress fibers was restored and the cells responded normally when incubated in buffer containing 1–24 ACTH. These results suggest that the actin components of the cytoskeleton are important determinants of corticotropin-induced steroidogenic responsiveness.     

Effects of adrenaline administration on the interrenal gland of the newt, Triturus carnifex: evidence of intraadrenal paracrine interactions

The existence of paracrine control of steroidogenic activity by adrenochromaffin cells in Triturus carnifex was investigated by in vivo adrenaline (A) administration. The effects were evaluated by examination of the ultrastructural morphological and morphometrical features of the tissues as well as the serum levels of aldosterone, noradrenaline (NA), and adrenaline. In March and July, adrenaline administration reduced aldosterone release (from 187.23 +/- 2.93 pg/ml to 32.28 +/- 1.85 pg/ml in March; from 314.60 +/- 1.34 pg/ml to 87.51 +/- 2.57 pg/ml in July) from steroidogenic cells. The cells showed clear signs of lowered activity: they appeared full of lipid, forming large droplets. Moreover, adrenaline administration decreased the mean total number of secretory granules in the chromaffin cells in July (from 7.74 +/- 0.74 granules/microm(2) to 5.14 +/- 1.55 granules/microm(2)). In this period T. carnifex chromaffin cells contain almost exclusively NA granules (NA: 7.42 +/- 0.86 granules/microm(2); A: 0.32 +/- 0.13 granules/microm(2)). Adrenaline administration reduced noradrenaline content (4.36 +/- 1.40 granules/microm(2)) in the chromaffin cells, enhancing noradrenaline secretion (from 640.19 +/- 1.65 pg/ml to 1030.16 +/- 3.03 pg/ml). In March, adrenaline administration did not affect the mean total number of secretory vesicles (from 7.24 +/- 0.18 granules/microm(2) to 7.25 +/- 1.97 granules/microm(2)). In this period the chromaffin cells contain both catecholamines, noradrenaline (3.88 +/- 0.13 granules/microm(2)), and adrenaline (3.36 +/- 0.05 granules/microm(2)), in almost equal quantities; adrenaline administration reduced adrenaline content (1.74 +/- 0.84 granules/microm(2)), increasing adrenaline release (from 681.27 +/- 1.83 pg/ml to 951.77 +/- 4.11 pg/ml). The results of this study indicate that adrenaline influences the steroidogenic cells, inhibiting aldosterone release. Adrenaline effects on the chromaffin cells (increase of noradrenaline or adrenaline secretion) vary according to the period of chromaffin cell functional cycle. The existence of intraadrenal paracrine interactions in T. carnifex is discussed.     

Cytoskeletal changes accompanying ACTH-induced steroidogenesis in cultured embryonic adrenal gland cells from the Pekin duck

Summary Cells derived from the adrenal glands of duck embryos immediately prior to hatching were grown in culture and used to study the morphological and cytoskeletal changes and steroidogenic responses induced by 1–24 ACTH. Changes in the cytoskeletal components were observed by rhodamine-phalloidin staining for actin and by staining the tubulin immunoreactive components with FITC. The cultures were comprised of a small population of chromaffin cells and a larger population of steroidogenic cells. The chromaffin cells were distinguished by their tyrosine hydroxylase immunoreactivity. The steroidogenic cells were characterized by the presence of sudanophilic lipid droplets, numerous mitochondria, abundant smooth endoplasmic reticulum, microtubules distributed as a fairly even network throughout the cytoplasm, and microfilaments that formed an extensive and elaborate system of stress fibers with many parallel arrays. The cells readily responded to stimulation with ACTH by releasing corticosterone, aldosterone and deoxycorticosterone. Stimulation with ACTH also induced changes in both the cell morphology and the cytoskeleton. Exposure of the cells to Krebs-Henseleit buffer containing 1–24 ACTH caused them to form numerous fine filopodia, to lose their stress fibers, and to form a thick ring of actin at the periphery of the cell. In addition, many cells became extremely arborized with many long branched dendritic processes. The morphological changes appeared to be related to a redistribution of the actin components, and may be explained only in part by the rounding up or retraction of the cytoplasm. The results strongly suggest an involvement of the actin components of the cytoskeleton in the steroidogenic response to corticotropic stimulation.     

Adaptation of aldosterone biosynthesis to sodium and potassium intake in the rat

The steroidogenic response of rat adrenal zona glomerulosa to stimulators is variable and depends on the activity of biosynthetic steps involved in the conversion of deoxycorticosterone (DOC) to aldosterone (Aldo). Corticosterone methyl oxidations (CMO) 1 and 2 are stimulated by sodium restriction and suppressed by potassium restriction. These slow alterations are accompanied by the appearance or disappearance of a specific zona glomerulosa mitochondrial protein with a molecular weight of 49,000. Induction of CMO 1 and 2 activities and the appearance of the 49 K protein can also be elicited in vitro by culture of rat zone glomerulosa cells in a medium with a high potassium concentration. The 49 K protein crossreacts with a monoclonal antibody raised against purified bovine adrenal cytochrome P-450(11 beta). The same antibody stains a protein with a molecular weight of 51,000 in rat zona fasciculata mitochondria and in zone glomerulosa mitochondria of rats in which CMO 1 and 2 activities have been suppressed by potassium restriction and sodium loading. The 51 K crossreactive protein was purified to electrophoretic homogeneity by chromatography on octyl-sepharose. In a reconstituted enzyme system, it converted DOC to corticosterone (B) and to 18-hydroxy-11-deoxycorticosterone (18-OH-DOC) but not to 18-hydroxycorticosterone (18-OH-B) or Aldo. A partially purified 49 K protein preparation from zona glomerulosa mitochondria of rats kept on a low-sodium, high-potassium regimen converted DOC to B, 18-OH-DOC, 18-OH-B and Aldo. According to these results, rat adrenal cytochrome P-450(11 beta) exists in two different forms, with both of them capable of hydroxylating DOC in either the 11 beta- of the 18-position, but with only the 49 K form capable of catalyzing CMO 1 and 2. The adaptation of aldosterone biosynthesis to sodium deficiency or potassium intake in rats is due to the appearance of the 49 K form of the enzyme in zona glomerulosa mitochondria.     

In vitro stimulation and inhibition of steroid hormone release from postovulatory follicles of the tilapia,Oreochromis mossambicus

Summary Postovulatory follicles of the tilapia, Oreochromis mossambicus, were incubated with graded doses of salmon gonadotropin to identify the steroid hormones released by this tissue. In addition, the effects of either cytochalasin B or colchicine on steroid hormone release were studied. After the incubation, the tissue was examined by electron microscopy. Postovulatory follicles released testosterone and estradiol-17B in a dose-dependent manner with gonadotropin. There was no detectable release of progesterone or 17a-OH-progesterone. When stimulated with high doses of gonadotropin, the steroidogenic cells showed an increase in smooth endoplasmic reticulum, Golgi complexes, and lipid droplets. Also, microfilaments became arranged in orderly bundles and were found close to the numerous secretory vesicles and lipid droplets. Upon incubation with gonadotropin and either colchicine or cytochalasin B, the cells still appeared steroidogenic, but the filaments were not organized nor associated with vesicles or lipid droplets. Release of steroid hormone decreased significantly. Also in these tissues, vesicles were no longer numerous in the apical region of the granulosa cells, but were located primarily near smooth endoplasmic reticulum and Golgi complexes. This suggests that disruption of the cytoskeleton results in reduced steroid hormone synthesis or release.     

Roles of Nicotinic and Muscarinic Receptors in Calcium Signaling and Transmitter Release

Activation of acetylcholine receptors (AChR) triggers catecholamine release from adrenal chromaffin cells and release of neurotransmitters in neuron-to-neuron and neuromuscular junctions, including those on smooth muscle cells. Calcium ions play the role of the main intracellular messenger, which mediates these processes. In our study, we explored the properties of Ca²⁺ signaling triggered by activation of AChR by analyzing the characteristics of Ca²⁺ transients induced by selective activation of nicotinic (nAChR) and muscarinic (mAChR) cholinoreceptors using Fura-2 fluorescent measurements in experiments on rat chromaffin cells. Two populations of chromaffin cells, which in a different manner responded to AChR stimulation, were classified. We found that the mean frequency of quantum release induced by ACh is considerably higher than that during hyperpotassium cell depolarization. Comparative analysis of single secretory events showed that, in the case of stimulation by ACh, single secretory spikes demonstrate faster kinetic characteristics than those induced by depolarization. Statistical analysis of the integral magnitude (area) of single secretory spikes evoked by both types of stimulation showed no significant difference despite amplitude and kinetic dissimilarities between such secretory events. Mathematical modeling of the dynamics of the exocytotic processes led to the conclusion that the reason for the specific kinetic characteristics of single secretory responses may be different diameters of the secretory pores formed during fusion of secretory vesicles with the plasma membrane.     

Saturated fatty acids suppress adrenocorticotropic hormone (ACTH) release from rat anterior pituitary cells in vitro

We studied whether fatty acids modify adrenocorticotropic hormone (ACTH) release induced by stimulation with corticotropin-releasing hormone (CRH) from rat anterior pituitary cells. Stimulation with CRH (0.01-100 nmol/l) significantly and concentration-dependently increased ACTH release, which was synergistically enhanced by the simultaneous stimulation with 1 nmol/l arginine-vasopressin. Addition of saturated fatty acids (butyrate, caprylate, laurate, palmitate and stearate) in a medium at 1 mmol/l, despite effects on the basal release, significantly reduced the ACTH release induced by CRH (1 nmol/l) stimulation. Caprylate suppressed ACTH release in a concentration-dependent manner. However, unsaturated C18 and C20 fatty acids (oleate, linolate, linolenate and arachidonate) at 1 mmol/l significantly increased the basal release, but none of them suppressed CRH (1 nmol/l)-induced ACTH release. In the presence of caprylate (1 mmol/l), CRH (1 nmol/l)-stimulated increase in cellular calcium ion concentration was diminished. From these results we conclude that saturated fatty acids have a suppressing effect on CRH-induced ACTH increase in primary cultured rat anterior pituitary cells.     

Production and Release of Acetylcholinesterase by a Primary Cell Culture of Bovine Adrenal Medullary Chromaffin Cells

Abstract: Bovine adrenal chromaffin cells were isolated and maintained as primary culture monolayers. Total acetylcholinesterase (AChE) activity in the cells increased during the culture period, and AChE activity appeared in the culture medium. We have examined the role of the AChE synthesized by the cells on ACh-evoked release of catecholamine from the cells. A progressive decrease in the efficacy of ACh (5 × 10-⁵m ) to evoke release of [³H] norepinephrine from day 3–15 cultures suggests that exogenously applied ACh is hydrolyzed by the nascent AChE synthesized by the cells. These findings provide evidence that chromaffin cells produce AChE and release it into their immediate environment.     

Changes in the adrenal steroidogenic responsiveness of the mallard duck (Anas platyrhynchos) during early post-natal development

1. Plasma concentrations of corticosterone (B), aldosterone (Aldo) and deoxycorticosterone (DOC) were measured in mallard ducklings immediately before and after exposure to acute immobilization stress. 2. Except for transient declines in B and DOC between the 4th and 14th days after hatching, the resting concentration of each hormone did not change significantly during post-natal development. 3. The stress-induced in Aldo was maximal at hatching while maximal increases in B and DOC did not occur until one day later. 4. Thereafter the magnitude of the stress-induced increases in the concentrations of all of the hormones decreased steadily and on the 21st and 28th days after hatching only B increased significantly in response to stress.     

Regulation by adrenocorticotropic hormone and arachidonate of the expression of acyl-CoA synthetase 4, an arachidonate-preferring enzyme expressed in steroidogenic tissues

Acyl-CoA synthetase 4 (ACS4) is an arachidonate-preferring enzyme abundant in steroidogenic tissues. We demonstrate that ACS4 expression in steroidogenic tissues in vivo is induced by adrenocorticotropic hormone (ACTH) and suppressed by glucocorticoid. ACTH also induced ACS4 protein but not its mRNA in Y1 adrenocortical tumor cells, whereas both ACS4 mRNA and protein were increased by dibutyryl cAMP (db-cAMP) and forskolin. Furthermore, the levels of ACS4 mRNA and protein in Y1 cells were induced by arachidonate. These data suggest that ACS4 expression in steroidogenic cells is regulated in coordination with induced steroidogenesis and arachidonate released by cholesterol ester hydrolase.     

Ouabain enhances exocytosis through the regulation of calcium handling by the endoplasmic reticulum of chromaffin cells

The augmentation of neurotransmitter and hormone release produced by ouabain inhibition of plasmalemmal Na⁺/K⁺-ATPase (NKA) is well established. However, the mechanism underlying this action is still controversial. Here we have shown that in bovine adrenal chromaffin cells ouabain diminished the mobility of chromaffin vesicles, an indication of greater number of docked vesicles at subplasmalemmal exocytotic sites. On the other hand, ouabain augmented the number of vesicles undergoing exocytosis in response to a K⁺ pulse, rather than the quantal size of single vesicles. Furthermore, ouabain produced a tiny and slow Ca²⁺ release from the endoplasmic reticulum (ER) and gradually augmented the transient elevations of the cytosolic Ca²⁺ concentrations ([Ca²⁺]_c) triggered by K⁺ pulses. These effects were paralleled by gradual increments of the transient catecholamine release responses triggered by sequential K⁺ pulses applied to chromaffin cell populations treated with ouabain. Both, the increases of K⁺-elicited [Ca²⁺]_c and secretion in ouabain-treated cells were blocked by thapsigargin (THAPSI), 2-aminoethoxydiphenyl borate (2-APB) and caffeine. These results are compatible with the view that ouabain may enhance the ER Ca²⁺ load and facilitate the Ca²⁺-induced-Ca²⁺ release (CICR) component of the [Ca²⁺]_c signal generated during K⁺ depolarisation. This could explain the potentiating effects of ouabain on exocytosis.     

Docking of chromaffin granules—A necessary step in exocytosis?

Putative docking of secretory vesicles comprising recognition of and attachment to future fusion sites in the plasma membrane has been investigated in chromaffin cells of the bovine adrenal medulla and in rat phaeochromocytoma (PC 12) cells. Upon permeabilization with digitonin, secretion can be stimulated in both cell types by indreasing the free Ca²⁺-concentration to M levels. Secretory activity can be elicited up to 1 hr after starting permeabilization and despite the loss of soluble cytoplasmic components indicating a stable attachment of granules to the plasma membrane awaiting the trigger for fusion. Docked granules can be observed in the electron microscope in permeabilized PC 12 cells which contain a large proportion of their granules aligned underneath the plasma membrane. The population of putatively docked granules in chromaffin cells cannot be as readily discerned due to the dispersal of granules throughout the cytoplasm. Further experiments comparing PC 12 and chromaffin cells suggest that active docking but not transport of granules can still be performed by permeabilized cells in the presence of Ca²⁺: a short (2 min) pulse of Ca²⁺ in PC 12 cells leads to the secretion of almost all releasable hormone over a 15 min observation period whereas, in chromaffin cells, with only a small proportion of granules docked, withdrawal of Ca²⁺ leads to an immediate halt in secretion. Transport of chromaffin granules from the Golgi to the plasma membrane docking sites seems to depend on a mechanism sensitive to permeabilization. This is shown by the difference in the amount of hormone released from the two permeabilized cell types, reflecting the contrast in the proportion of granules docked to the plasma membrane in PC 12 or chromaffin cells. Neither docking nor the docked state are influenced by cytochalasine B or colchicine. The permeabilized cell system is a valuable technique for thein vitro study of interaction between secretory vesicles and their target membrane.     

In vivo and in vitro studies on steroid metabolism in a case of primary aldosteronism with multiple lesions of adenoma and nodular hyperplasia

In order to systematically analyze the regulation and metabolism of steroid hormones in a case of primary aldosteronism with multiple lesions, including adenoma and nodular hyperplasia of the left adrenal gland, the amounts of 9 steroids (progesterone (P), 11-deoxycorticosterone (DOC), corticosterone (B), 18-hydroxycorticosterone (18-OH-B), aldosterone (Aldo), 17 alpha-hydroxyprogesterone (17-OH-P), 11-deoxycortisol (S), cortisol (F) and dehydroepiandrosterone sulfate (DHEAS)) contained in the plasma and in the adrenal tissues were measured. The patient (a 39-year-old female) was admitted to our hospital because of hypokalemia and hypertension. A diagnosis of primary aldosteronism was made on the basis of a complete evaluation, and an adenoma (1.8 x 1.2 cm), a nodular hyperplasia (0.5 x 0.5 cm), a microadenoma and a cortical nodule were found on the left adrenal gland. In vivo studies revealed that the plasma level of Aldo was high, but those of the other steroid hormones were within the normal range. After ACTH infusion, the plasma levels of the 9 steroid hormones increased by 2 to 17 times the base levels. In particular, the responses of DOC and B were markedly high. In vitro studies on P, DOC, B, Aldo and F content in the adenoma (A), the nodular hyperplasia (A'), the adjacent adrenal tissue (C) and the right normal adrenal tissue (D) revealed that, except for F, they were highest in A, followed by A', D and C in that order. In incubation studies with ACTH using A and C, it was found that the levels of 8 steroid hormones with the exception of DHEAS were high in A than in C. In particular, the response of B in A was markedly increased. These findings suggest that aldosteronoma produces 8 steroid hormones under conditions of excess ACTH, while at physiological levels of ACTH, it produces only Aldo in excess.     

Endocrine-disrupting effects of nonylphenol in the newt, Triturus carnifex (Amphibia, Urodela)

The aim of our study was to verify whether environmental concentrations of nonylphenol influenced the adrenal gland of Triturus carnifex. Newts were exposed to 19 μg/L nominal concentration of nonylphenol throughout the periods of December-January and March-April, corresponding to different stages of the chromaffin cell functional cycle. The morphological features of the steroidogenic and chromaffin tissues, and the serum levels of ACTH, aldosterone, corticosterone, norepinephrine and epinephrine were evaluated. Nonylphenol did not influence ACTH serum levels. During the two periods examined, the steroidogenic tissue had the same reaction: the quantity of cytoplasmic lipids, and the corticosteroid serum levels, decreased, suggesting the inhibition of synthesis and release of corticosteroids. During the two periods examined, the chromaffin tissue reacted differently to nonylphenol. During December-January, the numeric ratio of norepinephrine granules to epinephrine granules, and the epinephrine serum levels, increased, suggesting the stimulation of epinephrine release. During March-April, the numeric ratio of norepinephrine granules to epinephrine granules did not change, and the norepinephrine serum levels decreased, suggesting the inhibition of norepinephrine release. Our results show that nonylphenol influences the activity of the newt adrenal gland; considering the physiological role of this gland, our results suggest that nonylphenol may contribute to amphibian decline.     

Correlation between electrical activity and ACTH/beta-endorphin secretion in mouse pituitary tumor cells

The electrical and secretory activities of mouse pituitary tumor cells (AtT-20/D-16v), which contain and release the ACTH/beta-endorphin family of peptides, were studied by means of intracellular recordings and radioimmunoassays. Injection of depolarizing current pulses evoked action potentials in all cells and the majority (82%) displayed spontaneous action potential activity. Action potentials were found to be calcium-dependent. Barium increased membrane resistance, action potential amplitude and duration, and release of ACTH and beta- endorphin immunoactivity. Isoproterenol increased both action potential frequency and hormone secretion. Raising the external calcium concentration increased the frequency and amplitude of the action potentials and stimulated secretion of ACTH and beta-endorphin immunoactivity. Thus, stimulation of secretory activity in AtT-20 cells was closely correlated with increased electrical activity. However, a complete blockade of action potential activity had no effect on basal hormone secretion in these cells. These results suggest that the mechanisms underlying stimulated hormone secretion are different from those responsible for basal secretory activity. It is proposed that the increased influx of calcium due to the increased action potential frequency initiates the stimulated release of hormone from these cells.