Showing papers on "Adrenal cortex published in 1992"

Preclinical Cushing's syndrome in adrenal "incidentalomas": comparison with adrenal Cushing's syndrome.

Abstract: Adrenal tumors are usually diagnosed by clinical symptoms of hormone excess. The increasing use of ultrasound and computed tomography results in the detection of a substantial number of incidentally discovered adrenal tumors. Most of these tumors are nonfunctional adrenocortical adenomas, but a few cases of subclinical cortisol production in “incidentalomas” have been reported. We investigated prospectively the prevalence of autonomous cortisol production in 68 patients (44 females and 24 males, aged 25-90 yr) with adrenal incidentalomas at our institution. As a screening procedure all patients with incidentalomas underwent an overnight dexamethasone suppression test (1 mg). Patients who failed to suppress serum cortisol below 140 nmol/L (5 pg/dL) underwent more comprehensive studies (prolonged dexamethasone suppression test, determination of the diurnal rhythm of cortisol secretion in saliva, and CRH stimulation test). Eight patients (12% of all patients with incidentalomas; 5 females and 3 males, aged 25-71 yr) were finally identified as having cortisol-producing tumors, and the findings in these patients were compared with those of overt Cushina’s syndrome in 8 uatients (8 females. awd 26-50 yr) suffering from coriisoi-producing adrenal adenomas. The tumor size of patients with cortisol-producing incidentalomas ranged from 2-5 cm. No specific signs and symptoms of hypercortisolism were present, but arterial hypertension (seven of eight subjects), diffuse obesity (four of eight subjects), and noninsulin-dependent diabetes mellitus (NIDDM; two of eight subjects) were frequently observed. Baseline cortisol levels were in the normal to upper normal range, whereas baseline ACTH levels were suppressed in five of the eight patients. In none of the patients was serum cortisol suppressible by low dose or high dose dexamethasone. The ACTH and cortisol responses to CRH were normal in two, blunted in one, and suppressed in four patients. Unilateral adrenalectomy was performed in seven patients and resulted in temporary adrenal insufficiency in four of them. After surgery, improvement of arterial hypertension, a permanent weight loss in obese subjects, and a better metabolic control of NIDDM were noted in the majority of patients. The following conclusions were reached. Incidentally diagnosed adrenal tumors with pathological cortisol secretion in otherwise clinically asymptomatic patients are more frequently observed than previously assumed. Adrenocortical insufficiency is a major risk in these patients after adrenalectomy. After surgery, hypertension, obesity, and NIDDM may improve. Patients with asymptomatic adrenal incidentalomas, therefore, should be screened for cortisol production by means of an overnight dexamethasone suppression test. (J Clin Endocrinol Metab 75: 826-832, 1992)

Glucocorticoid-suppressible hyperaldosteronism results from hybrid genes created by unequal crossovers between CYP11B1 and CYP11B2.

Abstract: Glucocorticoid-suppressible hyperaldosteronism (GSH) is an autosomal dominant form of familial hypertension. The biochemical abnormalities seen in this disorder may be remedied by administration of dexamethasone, implying that aldosterone synthesis is being abnormally regulated by corticotropin. The final three steps of aldosterone synthesis, 11 beta- and 18-hydroxylation and 18-oxidation, are mediated by a cytochrome P450 in the zona glomerulosa of the adrenal cortex termed CYP11B2. A related isozyme in the zona fasciculata, CYP11B1, is required for cortisol synthesis; this isozyme, which is normally expressed at much higher levels than CYP11B2, only has 11 beta-hydroxylase activity. These isozymes are encoded by genes on human chromosome 8q22. We have now studied four unrelated patients with GSH. We found that each patient has one chromosome that carries three CYP11B genes instead of two. This has presumably been generated by unequal meiotic crossing-over. The extra gene is a hybrid with 5' regulatory and coding regions corresponding to CYP11B1 and 3' coding regions from CYP11B2. The breakpoint is in intron 2 in two cases, intron 3 in one, and exon 4 in one. Cells transfected with hybrid cDNAs containing up to the first three exons of CYP11B1 synthesized aldosterone at levels near that of cells carrying normal CYP11B2, but cells transfected with hybrids containing the first five or more exons of CYP11B1 could not synthesize detectable amounts of aldosterone. These data demonstrate that GSH is caused by expression of a gene that is regulated like CYP11B1 but that encodes a protein able to synthesize aldosterone.

Adrenal incidentaloma and patients with homozygous or heterozygous congenital adrenal hyperplasia

Abstract: Adrenal tumors are being detected more frequently in consequence of the wider application of increasingly sensitive radiological investigation techniques. According to the working hypothesis that more silent adenomas could develop from hyperplastic tissue areas under increased stimulation of the adrenal cortex, heterozygous and homozygous patients with congenital adrenal hyperplasia (CAH) were studied. A high incidence of adrenal masses, nearly 82% in homozygous and 45% in heterozygous patients, was found. There was no correlation between tumor size and serum 17-hydroxyprogesterone concentrations. These tumors are, therefore, probably silent adenomas. On the basis of these results, CAH should always be ruled out in the case of incidentally detected adrenal masses. Since CAH is a relatively frequent disease, and the adrenal carcinoma belongs to the rarest malignant tumors, a malignant transformation of these tumors seems to be unlikely.

Clinical and genetic features of adrenocortical lesions in multiple endocrine neoplasia type 1.

Abstract: In multiple endocrine neoplasia type 1 (MEN-1), benign enlargement of the adrenal cortex has been found in about one third of necropsy cases. To elucidate the clinical and genetic characteristics of the MEN-1 adrenal lesion, we have investigated 33 MEN-1 patients. Twelve individuals (37%) demonstrated adrenal enlargement, which was bilateral in 7 of them. Histopathology revealed diffuse and nodular cortical hyperplasia, adenomas, and a single case of adrenocortical carcinoma. The apparently benign adrenal enlargements were not associated with presently ascertainable biochemical disturbances in the hypothalamic-pituitary-adrenocortical axis, and they were without radiological signs of progression during follow-up. The individual developing unilateral adrenocortical carcinoma showed rapid adrenal expansion, feminization, and an abnormal urinary steroid profile after 4 yr of observation for bilateral minor adrenal enlargements. Pancreatic endocrine tumors were significantly overrepresented and present in all...

Acute endocrine failure after brain death

Abstract: After brain death, 32 potential organ donors were studied to determine serum and plasma concentrations of hypothalamic-pituitary hormones, thyroid hormones, and cortisol over a period of up to 80 hr. Diagnosis of brain death was established either on the basis of clinical criteria (n = 16) or by angiography (n = 16). While 78% of the organ donors developed diabetes insipidus, none of the circulating hormones of the anterior pituitary gland showed a progressive decline in concentration according to their plasma half-lives. With the exception of arginine vasopressin (AVP), no hormone concentration was found to be subnormal due to the onset of brain death. The subnormal free triiodothyronine (FT3) values in 62% of cases (median FT3 of 2.2 pmol/L within the first 24 hr) and the cortisol concentration of 6.9 micrograms/dl correlate with the frequency of similar findings in patients with severe head injuries. While the adrenocorticotropic hormone (ACTH) concentrations of 10-53 pg/ml remained constant during the study period, thyroid-stimulating hormone (TSH) and human growth hormone (hGH) concentrations showed a 12- and 35-fold increase from baseline values after 30-40 hr. These results suggest that, despite the now generally accepted criteria of brain death, there is still some residual function, and thus also perfusion of the hypothalamic-pituitary neuroendocrine system. This residual function appears to be sufficient to maintain hormonal plasma levels at least in the low reference range in most donors. Hormonal depletion in organ donors subsequent to brain death, as suggested repeatedly in the literature, could not be confirmed. The analysis of serum or plasma concentration patterns of a number of hormonal parameters following brain death does not support the rationale for a routine replacement therapy of total triiodothyronine (TT3) or cortisol to maintain endocrine homeostasis prior to organ harvest. However, dexamethasone therapy may be followed by suppression of the adrenal cortex of the organ donor. In these cases, cortisol substitution may be indicated.

Zone-specific expression of aldosterone synthase cytochrome P-450 and cytochrome P-45011 beta in rat adrenal cortex: histochemical basis for the functional zonation.

Abstract: Zonal distribution of aldosterone synthase cytochrome P-450 and cytochrome P-45011 beta in rat adrenocortex was investigated immunochemically using specific antibodies to these enzymes. Localization of aldosterone synthase cytochrome P-450 (cytochrome P-450aldo), a recently identified enzyme that converts deoxycorticosterone to aldosterone in rat adrenocortex was strictly confined to two or three outermost cell layers in the zona glomerulosa. In contrast, cytochrome P-45011 beta, which forms corticosterone, but not aldosterone, from deoxycorticosterone, was localized in the zona fasciculata-reticularis and not in the zona glomerulosa. Neither enzyme was detected in the medulla or the capsule. The functional zonation of adrenocortex with respect to aldosterone and corticosterone syntheses is, thus, ascribable to the localization of cytochromes P-450aldo and P-45011 beta in the respective zones. When rats were maintained under Na-depleted conditions for 10 days, the zona glomerulosa cells containing cytochr...

3 Disorders of the adrenal cortex

Abstract: Adrenal crisis represents the major endocrine emergency with a fatal outcome if not properly recognized and correctly treated. It can present as the first manifestation of acute or chronic primary adrenal failure. Secondary adrenal insufficiency with usually less dramatic manifestations can cause mental disturbances, electrolyte or metabolic disorders severe enough to warrant prompt correction and therapeutic intervention. This is particularly true in cases of abrupt cessation of steroid treatment, pituitary apoplexy and Sheehan's syndrome. Hyperfunction of the adrenal cortex, be it hypercorticism or hypermineralocorticism, can also require rapid treatment of electrolyte disorders and hypertension. The symptoms and differential diagnosis of these entities are described as well as their proper treatment. In order to confirm later the diagnosis, the need to secure biological samples for hormone determination before starting treatment is emphasized.

Activin and inhibin in the human adrenal gland. Regulation and differential effects in fetal and adult cells.

Abstract: Recent experimental data have revealed that activins and inhibins exert pivotal effects on development. As part of our studies on growth and differentiation of the human fetal adrenal gland, we examined the subunit localization, as well as the mitogenic and steroidogenic actions of activin and inhibin in human fetal and adult adrenals. All three activin and inhibin subunit proteins (alpha, beta A, and beta B) were detected in the fetal and adult adrenal cortex. Immunoreactive activin-A dimer was demonstrated in midgestation fetal and neonatal adrenals. ACTH1-24-stimulated fetal adrenal cell expression of alpha and beta A subunit messenger RNA. In addition, ACTH elicited a rise in levels of immunoreactive alpha subunit secreted by fetal and adult adrenal cells. Human recombinant activin-A inhibited mitogenesis and enhanced ACTH-stimulated cortisol secretion by cultured fetal zone cells, but not definitive zone or adult adrenal cells. Recombinant inhibin-A had no apparent mitogenic or steroidogenic effects. Thus, activin selectively suppressed fetal zone proliferation and enhanced the ACTH-induced shift in the cortisol/dehydroepiandrosterone sulfate ratio of fetal zone steroid production. These data indicate that activin-A may be an autocrine or paracrine factor regulated by ACTH, involved in modulating growth and differentiated function of the human fetal adrenal gland.

New developments in the pathologic diagnosis of adrenal cortical neoplasms. A review.

Abstract: In the past decade, our knowledge of neoplasms arising in the adrenal cortex has been expanded greatly. Histologic criteria for distinguishing benign from malignant adrenal cortical neoplasms have been developed. In this review, three systems useful in making this distinction are reviewed and compared. Pathologic indicators of prognosis for adrenal cortical carcinomas have been proposed and these include mitotic rate, stage, surgical resectability, nuclear grade, and tumor size. Of these, mitotic rate appears to be the best indicator. Adrenal cortical carcinomas with a high mitotic rate behave most aggressively. The role of immunohistochemical and DNA content analysis in the diagnosis of adrenal cortical neoplasms is limited. Neoplastic adrenal cortical cells contain a low density of keratins that is often destroyed by routine fixation and paraffin embedding. Thus, the absence of keratins in adrenal cortical neoplasms, particularly carcinomas, in routinely processed tissue should not dissuade the pathologist from making the diagnosis of an epithelial neoplasm. DNA content analysis has revealed an imperfect correlation between DNA ploidy and histologic diagnosis. Some adrenal cortical adenomas contain aneuploid stem cell lines, whereas some adrenal cortical carcinomas have diploid DNA content. Molecular genetic analyses suggest that one or more tumor suppressor genes may be involved in the pathogenesis of adrenal cortical neoplasms.

Genetic basis of endocrine disease 2: congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Abstract: Most cases of congenital adrenal hyperplasia, the inherited inability to synthesize cortisol, are caused by a deficiency of the 21-hydroxylase activity required to convert 17-hydroxyprogesterone to 11-deoxycortisol. Poor synthesis of cortisol results in chronic stimulation of the adrenal cortex by corticotropin with consequent overproduction of cortisol precursors. Some of these precursors are shunted into the androgen biosynthetic pathway causing the signs and symptoms of androgen excess seen in this disorder. The disease occurs in a wide spectrum of clinical variants, including a severely affected form with a concurrent defect in aldosterone biosynthesis (“salt wasting” type), a form with apparently normal aldosterone biosynthesis (“simple virilizing” type) and a mild “nonclassic” form that may be asymptomatic or may be associated with symptoms of androgen excess developing during childhood or at puberty (1). The disorder is inherited as a monogenic autosomal recessive trait located within the HLA major histocompatibility complex on chromosome 6~21.3. There are a number of associations between the different forms of 21-hydroxylase deficiency and specific combinations of HLA antigens, or haplotypes. In particular, the unusual haplotype A3;Bw47;DR7 is associated with about 10% of classic (i.e. salt wasting or simple virilizing) 21-hydroxylase deficiency alleles, whereas HLA-B14;DRl is associated with 70% of alleles for nonclassic disease. Based on these associations and on studies of pedigrees containing patients with the different forms of the disease, it appears that these forms are inherited as allelic variants. Classic disease occurs in approximately l/10,000 births, whereas nonclassic disease occurs in approximately 1% of the general population (2). The molecular genetic basis of 21-hydroxylase deficiency has been thoroughly studied. The 21-hydroxylase enzyme is a microsomal cytochrome P450 termed P45OXXI or P45Oc21. The structural gene encoding

Rat adrenal cortex is a source of a circulating ouabainlike compound

Abstract: To determine if the adrenal gland may be the source of plasma-borne ouabainlike compound (OLC) in rats, we 1) measured immunoreactivity expressed as OLC equivalents in extracts from a wide variety of central and peripheral tissues and, for adrenal cortex and medulla, chromatographed the extracts to determine to what extent immunoreactivity in the adrenal was OLC, and 2) measured OLC in the plasma of adrenalectomized and adrenal demedullectomized rats. The highest levels of immunoreactivity were found in adrenal cortex, adrenal medulla, atria, and the pituitary. Based on high-performance liquid chromatographic retention time, immunoreactivity in the adrenal cortex was almost exclusively immunoreactive OLC. Removal of this rich source of OLC from rats resulted in an approximate 50% decrease in circulating levels of OLC by 6 days after removal. Furthermore, although adrenal demedullectomy also caused a decrease in OLC 3 days after surgery, the decline was sustained only with total adrenalectomy, in that plasma levels of OLC in demedullectomized rats 6 days after surgery had returned to levels equal to those of sham controls. Taken together, these findings strongly suggest that the adrenal cortex is a major contributor to circulating OLC in the rat.

Physiological role of corticotropin-releasing factor in the control of adrenocorticotropin-mediated corticosterone release from the rat adrenal gland.

Abstract: Marked fluctuations in adrenal sensitivity to ACTH have been reported under both physiological (e.g. diurnal) and experimental conditions. Recently, we reported that immunoneutralization of CRF reduces resting corticosterone (cort) levels in rats without inducing concomitant reductions in plasma ACTH. We postulated an endogenous CRF mechanism that controls the adrenal sensitivity to ACTH. In the present study, this hypothesis was tested by iv infusion of human ACTH (0, 1, 3, and 10 ng/kg.min for 60 min) into dexamethasone-treated anaesthetized male Wistar rats. Serial blood samples were taken for the determination of ACTH and corticosterone by RIA (ACTHi, corti). Infusion of ACTH resulted in dose-dependent steady state plasma ACTHi levels, ranging from 50-600 pg/ml, which were not affected by prior administration of a rat monoclonal antibody to rat CRF (PFU 83). As expected, infusion of ACTH resulted in a dose-dependent increase in plasma corti. In PFU 83-treated rats, preinfusion plasma corti levels were reduced compared to those of rat immunoglobulin G-treated controls (7.8 +/- 1.2 vs 25.3 +/- 3.2 ng/ml). In addition, the corti responses to infusion of 1 and 3 ng/kg.min ACTH were suppressed by PFU 83. However, at a (near) maximally effective dose of ACTH (10 ng/kg.min), no differences in plasma corti were found between PFU 83 and immunoglobulin G-treated rats. These findings suggest that immunoneutralization of endogenous CRF results in a 3-fold reduction of the adrenal sensitivity to ACTH. Subsequently, we studied the possible effects of exogenous CRF on the isolated perfused adrenal gland in situ. In this preparation, CRF alone (1-100 pmol) or ACTH alone (5 fmol) did not affect the corti secretion rate or the flow rate of the perfusion medium through the gland. However, when given together a marked (up to 3.2 times) CRF dose-dependent stimulation of corti secretion and an increase (up to 1.7 times) in adrenal flow rate were obtained. In experiments with freshly dispersed adrenal cells in vitro, PFU 83 (1 microM) or CRF (0.1-10 nM) did not influence corti secretion when given alone and did not affect ACTH-induced corti secretion. It is unlikely, therefore, that CRF acts directly on the steroid-producing cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Dietary potassium supplementation and sodium restriction stimulate aldosterone synthase but not 11 beta-hydroxylase P-450 messenger ribonucleic acid accumulation in rat adrenals and require angiotensin II production.

Abstract: Increasing evidence indicates that the adrenal cortex of most mammalian species expresses distinct forms of cytochrome P-450(11 beta), a steroidogenic enzyme that catalyses the terminal steps in the biosynthesis of both glucocorticoids and mineralocorticoids. In the human, mouse, and rat, two genes have been isolated, designated CYP11B1 and CYP11B2. The product of CYP11B2 (aldosterone synthase) is required for the successive 11 beta-, 18-hydroxylations and 18-oxidation of deoxycorticosterone that lead to the production of aldosterone in the zona glomerulosa. In contrast, the product of CYP11B1 (11 beta-hydroxylase) mediates only the 11 beta-hydroxylation of deoxycorticosterone and 11-deoxycortisol. The recent identification of these two P-450(11 beta) isozymes mandates further analysis of their expression in different zones of the adrenal cortex, both under basal conditions and in response to conditions known to alter mineralocorticoid biosynthesis. To evaluate the expression of the two isozymes in different adrenocortical zones, we performed Northern blotting analyses with specific oligonucleotide probes that discriminated between the two forms of rat P-450(11 beta). The transcripts detected by the two probes were of similar size (2.7 kilobase), but differed in their zonal distribution: aldosterone synthase P-450 messenger RNA (mRNA) was detected only in zona glomerulosa, whereas 11 beta-hydroxylase P-450 was expressed in both zona fasciculata-reticularis and zona glomerulosa. Next, we analyzed the response of these two genes to various physiological and pharmacological interventions known to affect aldosterone biosynthesis. High potassium or low sodium diet given to rats for 1 week increased aldosterone synthase P-450 mRNA levels by approximately 5- and 6-fold, respectively. These increases, moreover, were significantly attenuated by treatment with captopril, an inhibitor of angiotensin-converting enzyme. In contrast, neither dietary manipulation significantly affected 11 beta-hydroxylase P-450 mRNA levels in any zone. Thus, stimulation of the terminal steps of aldosterone biosynthesis by variations in dietary intake of monovalent cations involves regulation of aldosterone synthase P-450 mRNA levels. Finally, captopril inhibited potassium induction of aldosterone synthase P-450 mRNA levels despite the presence of low plasma renin activity in the potassium-treated rats. This finding implicates intraadrenal angiotensin II formation in the effect of potassium on mineralocorticoid production.

Vasoactive intestinal peptide stimulation of aldosterone secretion by the rat adrenal cortex may be mediated by the local release of catecholamines.

Abstract: The effects of vasoactive intestinal peptide (VIP) on adrenocortical function were investigated using several different preparations of adrenocortical tissue VIP caused a significant increase in perfusion medium flow rate and in aldosterone and corticosterone secretion by the isolated perfused rat adrenal gland, with a threshold of 1 pmol in 200 microliters, but did not affect basal steroid secretion by collagenase-dispersed adrenocortical cells at any concentration used, from 10 pmol/l to 10 mumol/l The presence of VIP (100 nmol/l) had no significant effect on the response of zona glomerulosa cells to stimulation by ACTH at any concentration In incubations of intact adrenal capsular tissue, VIP (10 mumol/l) caused a significant stimulation of aldosterone secretion, and also induced a significant release of adrenaline into the incubation medium Addition of (-)alprenolol (100 nmol/l), a beta-adrenergic antagonist, to the incubation medium significantly attenuated the response of capsular tissue to VIP It is concluded that the effects of VIP on aldosterone, which are only seen when the architecture of the zona glomerulosa is preserved, may be mediated by the local release of adrenaline

Adrenocorticotropin increases interleukin-6 release from rat adrenal zona glomerulosa cells.

Abstract: Interleukin-6 (IL-6) is produced by adrenal zona glomerulosa cells; its release is stimulated by several secretagogues, including IL-1 alpha, IL-1 beta, and angiotensin II. The present study reports that ACTH (0.1-100 nM) increased the release of IL-6 from primary cultures of rat adrenal cells in a concentration-dependent manner. This increase was accompanied by an increase in cAMP content in cell extracts and in the incubation medium. The dynamics of IL-6 release from the adrenal cells also were investigated using a perifusion system; approximately 50 min were required for the effects of IL-1 alpha, IL-1 beta, and ACTH on IL-6 release to become apparent. Following withdrawal of the secretagogues, IL-6 release returned to basal levels within 90-120 min. In some experiments, the adrenal zona glomerulosa was separated from the zona fasciculata/reticularis to determine the origin of secretagogue-stimulated IL-6 release. PGE2 and forskolin increased IL-6 release from both cell types, but maximal release from ...

Mechanism of angiotensin II-induced proliferation in bovine adrenocortical cells.

Abstract: The peptide hormone angiotensin-II (AII) is a potent vasoconstrictor and major regulator of aldosterone synthesis. In addition, AII also has growth-promoting effects. We have recently shown that the lipoxygenase (LO) pathway of arachidonic acid plays a major role in AII-induced aldosterone synthesis in adrenal glomerulosa cells. The LO pathway is also involved in the vasopressor and renin-inhibitory effects of AII. However, the role of LO products in AII-induced mitogenic effects have not yet been investigated. In the present studies we have evaluated the role of the LO pathway in AII-induced proliferative responses in a bovine adrenocortical cell clone termed AC1 cells. In addition, the potential receptor type and mechanism of AII-induced proliferation was studied by evaluating the effect of specific nonpeptide type 1 and type 2 AII receptor antagonists and the role of protein kinase-C (PKC). AII-induced DNA synthesis was significantly attenuated by two structurally dissimilar LO inhibitors, baicalein and phenidone. In addition, the LO product 12-hydroxyeicosatetraenoic acid (12-HETE) itself caused a significant increase in DNA synthesis, suggesting that the 12-LO pathway in part plays a role in AII-mediated mitogenesis. AII-induced proliferative responses were blocked by the type 1 AII receptor antagonist. Both AII- and 12-HETE-induced increases in DNA synthesis were markedly inhibited by two PKC blockers, staurosporine and sangivamycin. Further, both AII and 12-HETE could activate PKC by translocating it from the cytosol to the membrane fraction, as determined by Western immunoblotting. These results suggest that both 12-LO activation and protein kinase-C have an important role in AII-induced adrenal cell proliferation.

Steroid hormone receptors in the adrenal glands of fetal and adult rhesus monkeys.

Abstract: Sex steroid hormone receptors have been identified in the adrenal glands of rodents and may have a role in adrenal function. The highly estrogenic environment during pregnancy has been proposed to influence steroidogenesis by the fetal zone of the primate fetal adrenal gland. In order to determine whether these effects involve receptor-mediated mechanisms, we have examined the concentration and distribution of estrogen receptor (ER), androgen receptor, and progesterone receptor (PR) in the adrenal glands of fetal, immature, and adult rhesus monkeys. Monoclonal antibodies were used for immunocytochemistry (ICC), and in a gradient shift assay, for determination of receptor distribution and concentrations, respectively. There was no difference between the concentrations of ER in the adrenal glands from male and female adult animals (12.4 +/- 2.2, n = 3 and 13.2 +/- 2.0 fmol/mg DNA, n = 7; respectively); however, the concentration of ER in the fetal adrenal glands was markedly lower than in the adults (combined adult 12.7 +/- 1.6, n = 10, and fetal 0.9 +/- 0.4 fmol/mg DNA, n = 7; P less than 0.01). The concentration of ER in the adrenal glands of immature animals was also lower compared to adult animals (6.1 +/- 1.6, n = 6, P less than 0.05). In the adult, ICC revealed that staining for ER was restricted to the cell nucleus and was most dense in the zone fasciculata, with lesser staining in the zona glomerulosa and zona reticularis, and with no detectable staining in the medulla. ER staining was virtually absent in the fetal zone which comprises the major portion of the fetal gland; however, some staining was observed in the narrow definitive zone. The distribution of androgen receptor was similar to that of ER, whereas there was no detectable staining for PR in the adrenals of either adult or fetal animals. We conclude: 1) that the lower concentration of ER in fetal adrenal glands is due to the absence of ER in the fetal zone; 2) the lack of ER and PR in the fetal zone suggests that estrogens and progestins do not influence the growth or function of the fetal zone by receptor-mediated mechanisms; 3) estrogens and androgens may influence the function of the adult adrenal cortex.

Direct secretagogue effect of corticotropin-releasing factor on the rat adrenal cortex: the involvement of the zona medullaris.

Abstract: CRF dose-dependently enhanced corticosterone (B) secretion by rat adrenal slices including both cortex and medulla. Conversely, CRF did not exert any B response by fragments of adrenocortical autotransplants, which are completely deprived of chromaffin tissue. However, autotransplant quarters exhibited a dose-dependent response to ACTH qualitatively similar to that of adrenal slices, although markedly less intense. The maximal B response of adrenal slices to CRF (10(-8) M) was completely annulled by corticotropin-inhibiting peptide (10(-6) M), a competitive inhibitor of ACTH, which totally blocked the secretory response to ACTH (10(-8) M) of both kinds of preparations. ACTH immunoreactivity was present in the adrenal gland of control rats, but was undetectable in autotransplanted adrenocortical nodules. Moreover, adrenal fragments mainly composed of chromaffin tissue released detectable amounts of ACTH in response to high concentrations of CRF (10(-8)/10(-6) M). These findings suggest that chromaffin medu...

Disorders of steroid 11β-hydroxylase isozymes

Abstract: Steroid 11 beta-hydroxylase activity in the adrenal cortex is required for the synthesis of the major glucocorticoids and mineralocorticoids, but different isozymes mediate this conversion in the zona fasciculata, where cortisol is produced, and the zona glomerulosa, the site of aldosterone synthesis. The isozyme in the latter zone also has 18-hydroxylase and 18-oxidase activities that are required for aldosterone synthesis. Mutations in the genes encoding these isozymes respectively result in defective synthesis of cortisol and aldosterone. Recombinations between the two genes that alter the regulation of the isozyme responsible for aldosterone synthesis cause an inherited form of hypertension, glucocorticoid-suppressible hyperaldosteronism.

Glucocorticoids stimulate transcription of the rat phenylethanolamine N-methyltransferase (PNMT) gene in vivo and in vitro.

Abstract: 1. PhenylethanolamineN-methyltransferase (PNMT) is regulated by glucocorticoid hormones. This study investigates the ability of glucocorticoids to modulate transcription of the rat PNMT genein vivo andin vitro. 2. In the adrenal glands of hypophysectomized (HPX'd) rats, the synthetic glucocorticoid dexamethasone (DEX) stimulates production of PNMT mRNA. Quantitative hybridization reveals that the levels of PNMT mRNA increase approximately threefold in total and poly(A)+ RNA after 4 days of DEX treatment of HPX'd rats, a level which is maximal for this treatment. 3. ACTH, the hormonal stimulus of glucocorticoid biosynthesis in the adrenal cortex, enhances PNMT mRNA production to levels comparable to that achieved with DEX in this system. The steroid responsiveness of PNMT message production is specific for glucocorticoids. DEX also increases PNMT mRNA in the brain stem, although the magnitude and speed of response are lower than observed in the adrenal gland. 4. Additional confirmation of the inductive ability of glucocorticoids is demonstrated by the increase in PNMT immunoprecipitated following translationin vitro of adrenal RNAs from DEX-treated rats. Furthermore, the PNMT mRNA signal obtained byin situ hybridization histochemistry in adrenal sections and in primary cultures of dispersed rat adrenal medullae reveals that DEX effects on PNMT mRNA can be elicited bothin vivo andin vitro. 5. Specifically, glucocorticoids exert their effects on expression of PNMT mRNA by elevating the rate of PNMT gene transcription: a 2.3-fold increase in PNMT transcription persists for 18 hr following DEX treatment of HPX'd rats. In summary, this study establishes that glucocorticoids directly and rapidly stimulate transcription of the rat PNMT gene.

Ultrastructural evidence for a paracrine regulation of the rat adrenal cortex mediated by the local release of catecholamines from chromaffin cells.

Abstract: The adrenal glands of perfusion fixed rats were investigated by light and electron microscopy. Within the rat adrenal cortex occurred rays and islets of chromaffin cells which were in close contacts with cortical cells on the electron microscopical level. We achieved to catch the process of exocytosis from a chromaffin cell located within the zona glomerulosa in direct apposition with an adrenocortical cell. The documentation of an exocytotic process from a chromaffin cell neighbouring a cortical cell provides direct evidence in support of a paracrine regulation of the cortex mediated by chromaffin cells.

Catecholamines released from local adrenergic axon terminals are possibly involved in fine tuning of steroid secretion from zona glomerulosa cells: functional and morphological evidence.

Abstract: The effect of supramaximal electric field stimulation on [3H]noradrenaline (NA) release and hormone production by rat adrenal capsule-glomerulosa preparations was studied using a microvolume perfusion system. A substantial proportion (about 20%) of nerve endings (varicosities) were observed close to zona glomerulosa cells, and about half of them appeared to be catecholaminergic, as judged by the chromaffin reaction of the synaptic vesicles studied at electron microscopic level. In tissue, preloaded with [3H]NA, the release of NA in response to electrical stimulation was frequency-dependent. Reserpinization, calcium removal or inhibition of Na+ influx by tetrodotoxin completely blocked NA release by field stimulation, indicating that the release resulted from axonal activity and is of vesicular origin. Neither the alpha 2-adrenoceptor agonist xylazine nor the muscarine-receptor agonist oxotremorine affected the stimulation-evoked release of [3H]NA, suggesting that, in contrast with other neurones present in the central nervous system or in the peripheral autonomic nervous system but like those in the median eminence, these axon terminals contained few presynaptic modulatory receptors. The NA (10.20 +/- 1.79 (S.E.M.) micrograms/g, n = 9), adrenaline (24.38 +/- 5.50 micrograms/g, n = 9) and dopamine (0.35 +/- 0.09 micrograms/g, n = 6) contents of the preparations were high, as determined by high-performance liquid chromatography. Our observations that the release and content of NA is high, and that a substantial proportion of catecholaminergic axon terminals lie in close proximity to zona glomerulosa cells (median value of the distance 300 nm) or to smooth muscle cells of the vessels, suggest that NA released from local adrenergic neurones without being presynaptically modulated may play an important role in fine-tuning both steroid production and/or blood flow through the gland, itself a powerful modulator of the adrenocortical response. This local modulating effect of NA may be especially significant when sympathetic activity is enhanced.