Regulation of zonation and homeostasis in the adrenal cortex

The adult adrenal cortex is organized into concentric zones, each specialized to produce distinct steroid hormones. Cellular composition of the cortex is highly dynamic and subject to diverse signaling controls. Cortical homeostasis and regeneration rely on centripetal migration of steroidogenic cells from the outer to the inner cortex, which is accompanied by direct conversion of zona glomerulosa (zG) into zona fasciculata (zF) cells. Given the important impact of tissue structure and growth on steroidogenic function, it is essential to understand the mechanisms governing adrenal zonation and homeostasis. Towards this end, we review the distinctions between each zone by highlighting their morphological and ultra-structural features, discuss key signaling pathways influencing zonal identity, and evaluate current evidence for long-term self-renewing stem cells in the adult cortex. Finally, we review data supporting zG-to-zF transdifferentiation/direct conversion as a major mechanism of adult cortical renewal.

[Heterozygosity for Mutations Affecting Coat Pigmentation in the American Mink (Neovison vison) Enhances Structural Stability of Adrenal Cortex under Stress Conditions]

The results of the study of the effects of heterozygosity for mutations affecting coat pigmentation on the response to the environmental stress caused by extreme feeding conditions are provided. The animals with the following genotypes were taken into the study: homozygotes standard (+/+), hedlund white (h/h), and aleutian (a/a) and heterozygotes hedlund white (h/+) and aleutian (a/+). The animals homozygous for the aleutian mutation (a/a) showed a statistically lower growth rate than the animals of other genotypes both in the ontrol and in the experiment (p < 0.05). Under the control conditions, the animals homozygous forboth the wild type standard allele (+/+) and the mutant hedlund white (h/h) and aleutian (a/a) alleles showed the evident tendency for the zona fasciculata and zona reticularis of the adrenal cortex broadening compared to the experimental conditions. At the same time, in the animals heterozygous for the hedlund white (h/+) and the aleutian (a/+) mutations, a clear tendency for increasing size of the zona fasciculata and zona reticularis under the experimental conditions was observed. In the heterozygous animals, although we observed single destructive changes in the adrenal cortex under stress conditions, they were much less profound than in the homozygous ones. This may be related to the broader range of morphological adaptation in the heterozygotes, which gives them the possibility of more significant enlargement of the secreting zone to provide for its adequate functioning.

Histocytological specificities of adrenal cortex in the New World Monkeys, Aotus lemurinus and Saimiri boliviensis

The New World monkey Aotus spp. (night monkeys) are expected for use of valuable experimental animal with the close species of Saimiri spp. (squirrel monkeys). Saimiri is known to show spontaneous hypercortisolemia, although few reports in Aotus. We compared basic states of blood steroid hormones and histological structure of the adrenal glands in two monkeys. Serum cortisol and ACTH levels were statistically lower in Aotus than Saimiri. Conversely, Aotus adrenocortical area showed significant enlargement, especially at the zona fasciculata. Electron microscopic observation at Aotus fasciculata cells revealed notable accumulation of large lipid droplets and irregular shapes of the mitochondrial cristae. These results suggest potential differences in cellular activities for steroidogenesis between Aotus and Saimiri and experimental usefulness in adrenocortical physiology and pathological models.

Adrenarche: a cell biological perspective

Adrenarche is a cell biological and endocrinological puzzle. The differentiation of the zona reticularis in childhood in humans requires special techniques for study because it is confined to humans and possibly a small number of other primates. Despite the rapid progress in the definition of adrenocortical stem/progenitor cells in the mouse, the factors that cause the differentiation of adrenocortical cells into zonal cell types have not been identified. There are, however, many candidates in the Wnt, Hedgehog, and other families of signaling molecules. A suitable system for identifying authentic stem cells, capable of differentiation into all zones, has yet to be developed. It is proposed here that the in vitro differentiation of pluripotent cells, combined with appropriate in vitro and in vivo methods for validating authentic adrenocortical stem cells, is a promising approach to solving these questions.

Central effects of ghrelin on the adrenal cortex: a morphological and hormonal study

Ghrelin, a growth hormone secretagogue that exerts an important role in appetite and weight regulation, participates in the activation of the hypothalamo-pituitary-adrenal (HPA) axis. Male Wistar rats (5/group) received daily for 5 days, via an ICV (intracerebroventricular) cannula, 5 microl phosphate buffered saline with or without 1 microg of rat ghrelin. Two hours after the last injection, blood and adrenal glands were collected from decapitated rats for blood hormone analyses and histologic and morphometric processing. Ghrelin treatment resulted in increased (p<0.05) body weight (13%), absolute whole adrenal gland weight (18%) and whole adrenal gland volume (20%). The absolute volumes of the entire adrenal cortex, ZG, ZF, and ZR also increased (p<0.05) after ghrelin by 20%, 21%, 21% and 11%, respectively. Ghrelin-treated rats had elevated (p<0.05) blood concentrations of ACTH, aldosterone and corticosterone (68%, 32% and 67%, respectively). The data clearly provide both morphological and hormonal status that ghrelin acts centrally to exert a global stimulatory effect on the adrenal cortex. Clarifying of the ghrelin precise role in the multiple networks affecting the stress hormone release, besides its well known energy and metabolic unbalance effects, remains a very important research goal.

Quantitative analysis of patch patterns in mosaic tissues with ClonalTools software

Quantitative analysis of mosaic tissues is a powerful method for following developmental lineages; however, analytical techniques are often subjective and repetitious. Here a flexible, semi-automated image analysis method for mosaic patterns is described. ClonalTools is a free customizable tool-set designed for the open-source image analysis package ImageJ. Circular, polygonal or linear one-dimensional mosaic arrays can be interrogated to provide measurements of the total number and width of positive and negative patches in a region of interest. These results are adjusted for the effects of random clumping using a previously described method to correct for differences in the contribution of the positive and negative cell type. The applicability of ClonalTools to different systems is discussed with reference to the analysis of mosaic patterns in the mouse corneal epithelium and adrenal cortex and in the outgrowth of neurites from explant cultures of mouse retina as example systems. To validate ClonalTools quantitatively, a recently published manual clonal analysis of the corneal epithelium of X-inactivation beta-Gal-mosaic mice was re-analysed. The semi-automated results did not differ significantly from the published data. Rapid quantification of such patterns to produce biologically relevant results represents a welcome improvement in terms of ease and speed of use over previous methods.

Development of the human adrenal zona reticularis: morphometric and immunohistochemical studies from birth to adolescence

Age-related morphologic development of human adrenal zona reticularis (ZR) has not been well examined. Therefore, in this study, 44 human young adrenal autopsy specimens retrieved from large archival files (n=252) were examined for immunohistochemical and morphometric analyses. Results demonstrated that ZR became discernible around 4 years of age, and both thickness and ratio per total cortex of ZR increased in an age-dependent fashion thereafter, although there was no significant increment in total thickness of developing adrenal cortex. We further evaluated immunoreactivity of both KI67 and BCL2 in order to clarify the equilibrium between cell proliferation and apoptosis in the homeostasis of developing human adrenals. Results demonstrated that proliferative adrenocortical cells were predominantly detected in the zona glomerulosa and partly in outer zona fasciculata (ZF) before 4 years of age and in ZR after 4 years of age, but the number of these cells markedly decreased around 20 years of age. The number of BCL2-positive cells increased in ZR and decreased in ZF during development. Adrenal androgen synthesizing type 5 17beta-hydroxysteroid dehydrogenase (HSD17B5 or AKR1C3 as listed in the Hugo Database) was almost confined to ZR of human adrenals throughout development. HSD17B5 immunoreactivity in ZR became discernible and increased from around 9 years of age. Results of our present study support the theory of age-dependent adrenocortical cell migration and also indicated that ZR development is not only associated with adrenarche, but may play important roles in an initiation of puberty.

Adrenal changes associated with adrenarche

The mechanisms causing the rise in adrenal androgen production during the course of adrenarche remain to be defined. However, the increase in steroid release is clearly associated with a series of intra-adrenal changes in the expression of steroidogenic enzymes needed for dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) production, as well as an expansion of the adrenal zona reticularis (ZR). We and others have defined the adrenal expression pattern of key steroidogenic enzymes during adrenarche. As adrenarche proceeds, the expanding ZR expresses greater levels of cytochrome b5 (CYB5) and steroid sulfotransferase (SULT2A1) than the adjacent fasciculata. In contrast, the growing ZR is deficient in 3beta-hydroxysteroid dehydrogenase type 2 (HSD3B2). The resulting profile of steroidogenic enzymes lends itself to the production of adrenal androgens and appears to track the progression of adrenarche. This article reviews the intra-adrenal changes of the adrenal cortex associated with adrenarche.

Long-term voluntary exercise and the mouse hypothalamic-pituitary-adrenocortical axis: impact of concurrent treatment with the antidepressant drug tianeptine

We investigated whether voluntary exercise and concurrent antidepressant treatment (tianeptine; 20 mg/kg/day; 4 weeks) exert synergistic effects on the mouse hypothalamic-pituitary-adrenocortical (HPA) axis. Animals had access to a running wheel, were treated with the antidepressant, or received both conditions combined. Control mice received no running wheel and no drug treatment. Exercise resulted in asymmetric changes in the adrenal glands. Whereas sedentary mice had larger left adrenals than right ones, this situation was abolished in exercising animals, mainly due to enlargement of the right adrenal cortex. However, antidepressant treatment alone was ineffective whereas the combination of antidepressant treatment and exercise resulted in an enlargement of both adrenal cortices. In these respective conditions, the levels of tyrosine hydroxylase (TH) mRNA expression in the left and right adrenal medullas varied greatly in parallel to the changes observed in the adrenal cortex sizes. TH mRNA expression in the locus coeruleus of exercising mice was significantly increased irrespective of concomitant tianeptine treatment. Corticotrophin-releasing factor mRNA levels in the hypothalamic paraventricular nucleus were decreased after voluntary exercise but were unaffected by tianeptine. Exercise, particularly in combination with tianeptine treatment, resulted in decreased early morning baseline plasma levels of corticosterone. If animals were exposed to novelty (i.e. a mild psychological stressor), a decreased response in plasma corticosterone levels was observed in the exercising mice. By contrast, after restraint, a mixed physical and psychological stressor, exercising mice showed an enhanced response in plasma corticosterone compared to the controls; a response which was even further boosted in exercising mice concomitantly treated with tianeptine. Under either condition, plasma adrenocorticotrophic hormone levels were not different between groups. Thus, voluntary exercise impacts substantially on HPA axis regulation. Concurrent tianeptine treatment results in synergistic actions, mainly at the adrenal level, affecting both its structure and function.

The effects of fasting and refeeding on adrenal cortex morphometry and serum concentrations of ACTH and corticosterone in young and old male rats

The impairment of homeostatic mechanisms in ageing becomes often apparent upon physiological or pathological stimulation. We have previously shown that fasting and refeeding revealed the existence of age-related changes of carbohydrate and lipid metabolism. Because fuel metabolism is partially controlled by corticosteroids we decided to determine the effects of refeeding on adrenal gland morphometry, ACTH, and corticosterone serum levels in young (5 mo) and (20 mo) old male Wistar rats. Fasting for 48 h did not change serum ACTH and corticosterone in both age groups. ACTH level did not change after 24 h of refeeding in young and old rats. However, in old, but not young animals, refeeding resulted in the decrease of corticosterone serum concentration. The relative weight of adrenal gland (% of body weight) did not change significantly with age (p=0.05). Fasting for 48 h induced in old rats but not in young ones increase of relative adrenal weight, and the volume of the reticular zone. Refeeding reduced adrenal volume, fascicular zone and reticular zone. Refeeding for 24 h decreased the total volume of adrenal gland of old rats due to a decline of the volumes of fascicular and reticular zones. In young rats refeeding reduced the volume of reticular zone. It is concluded that refeeding revealed ageing-dependent decline in the secretion of corticosterone, the key hormone of prolonged stress response.

Morphometric and statistical analysis of macro- and microscopic characteristics of the brain and their relationships with adrenocortical histophysiology in newborn rats

A direct relationship between the weights of the brain and hemisphere and parameters characterizing the development of the cortex and its neurons in intact newborn rats was revealed. Parameters of brain development in newborn rats correlate with 3beta-hydroxysteroid dehydrogenase activity in the adrenal zona glomerulosa.

V1a vasopressin receptors maintain normal blood pressure by regulating circulating blood volume and baroreflex sensitivity

Arginine-vasopressin (AVP) is a hormone that is essential for both osmotic and cardiovascular homeostasis, and exerts important physiological regulation through three distinct receptors, V1a, V1b, and V2. Although AVP is used clinically as a potent vasoconstrictor (V1a receptor-mediated) in patients with circulatory shock, the physiological role of vasopressin V1a receptors in blood pressure (BP) homeostasis is ill-defined. In this study, we investigated the functional roles of the V1a receptor in cardiovascular homeostasis using gene targeting. The basal BP of conscious mutant mice lacking the V1a receptor gene (V1a-/-) was significantly (P < 0.001) lower compared to the wild-type mice (V1a+/+) without a notable change in heart rate. There was no significant alteration in cardiac functions as assessed by echocardiogram in the mutant mice. AVP-induced vasopressor responses were abolished in the mutant mice; rather, AVP caused a decrease in BP, which occurred in part through V2 receptor-mediated release of nitric oxide from the vascular endothelium. Arterial baroreceptor reflexes were markedly impaired in mutant mice, consistent with a loss of V1a receptors in the central area of baroreflex control. Notably, mutant mice showed a significant 9% reduction in circulating blood volume. Furthermore, mutant mice had normal plasma AVP levels and a normal AVP secretory response, but had significantly lower adrenocortical responsiveness to adrenocorticotropic hormone. Taken together, these results indicate that the V1a receptor plays an important role in normal resting arterial BP regulation mainly by its regulation of circulating blood volume and baroreflex sensitivity.

Adrenocortical effects of oral estrogens and soy isoflavones in female monkeys

The goal of this study was to evaluate the long-term adrenocortical effects of premenopausal oral contraceptives (OC) and postmenopausal conjugated equine estrogens (CEE) and soy isoflavones in a female cynomolgus monkey model. Half of the animals received a triphasic OC for a period of 26 months, after which all monkeys were ovariectomized and randomized to one of three diet groups for 36 months: 1). isoflavone-depleted soy protein (control) (n = 54); 2). soy protein with isoflavones (129 mg/d equivalent) (SPI+) (n = 56); or 3). isoflavone-depleted soy protein with CEE (0.625 mg/d equivalent) (n = 59). In the premenopausal phase, OC treatment resulted in significantly higher cortisol (F) and lower dehydroepiandrosterone sulfate, androstenedione, and testosterone relative to intact controls. In the postmenopausal phase, CEE treatment resulted in significantly higher basal F and lower dehydroepiandrosterone sulfate, androstenedione, and testosterone when compared with control and SPI+ diets. Serum F and androgens in the SPI+ group did not differ significantly from the control group. The SPI+ group had significantly lower adrenal weight than either control or CEE groups, and this effect was localized primarily to the zona fasciculata region of the adrenal cortex. These findings suggest that long-term estrogen treatment may contribute to an androgen-deficient and hypercortisolemic state.

Role of adrenocorticotropic hormone in the development and maintenance of the adrenal cortical vasculature

The adrenal cortex is a highly vascularized endocrine tissue. A dense network of blood capillaries centripetally irrigates the adrenal gland, allowing every endocrine cell to be in contact with an endothelial cell. The pituitary hormone ACTH controls the coordinated development of the vasculature and the endocrine tissue mass. This suggests that paracrine secretions between steroidogenic adrenocytes and capillary endothelial cells participate in the control of adrenocortical homeostasis. Besides its effect on the vascular tone of arteries, ACTH induces the expression of the angiogenic cytokine VEGF-A (vascular endothelial growth factor-A) in primary cultures of adrenocortical cells. This growth factor is a specific mitogen for endothelial cells and is likely to mediate the hormonal control of adrenocortical vascularization through a paracrine mechanism. The newly discovered angiogenic factor EG-VEGF (endocrine-gland-derived vascular endothelial growth factor), the expression of which is restricted to endocrine glands and which is preferentially mitogenic for endocrine tissue-derived endothelial cells, is another candidate mediator of great potential interest.

Hypothalamo-pituitary-adrenocortical axis function and hedonic behavior in adult male and female rats prenatally stressed by maternal food restriction

Neuroendocrine activation during stress is affected by many factors contributing to the variability of the stress response. The present study was aimed at evaluating long-term changes in hypothalamo-pituitary-adrenocortical (HPA) axis function and in hedonic behavior in adult offspring prenatally stressed by maternal food restriction, with attention on possible gender differences. Adult offspring were blood sampled via a tail artery cannula. Prenatally stressed females had significantly higher adrenal weights compared to males. Plasma ACTH levels, which rose in response to acute stress induced by handling, were significantly higher in females compared to those in males. A similar pattern was found in plasma corticosterone. The rise in ACTH levels was more pronounced in prenatally stressed rats though the rise in corticosterone failed to be modified. Corticotropin releasing hormone (CRH) and proopiomelanocortin mRNA levels in the hypothalamic paraventricular nucleus and anterior pituitary, respectively, were found to be unchanged. The present experiments failed to reveal a decrease in hedonic behavior in prenatally stressed rats. In contrast, in male offspring a tendency to a higher sucrose preference was observed. These data together with observed changes in hormone and CRH mRNA levels indicate that the gestational stress used did not result in a depression-like state in adult offspring.

The morphometric parameters of adrenal cortex in sows: in normal condition and after prolactin infusion

The aim of this study was to examine the effect of experimental hyperprolactinemia on the stereological parameters of porcine adrenal cortex. In cyclic sows, after preovulatory luteinizing hormone (LH) peak, porcine prolactin (PRL, 0.3 mg) or saline were administered i.v. for 48 h at 2 h intervals. Next sows were slaughtered and adrenal glands were dissected. Stereological analysis of the left adrenal gland did not reveal any significant differences between control and PRL-treated sows. Experimental hyperprolactinemia did not affect the volume of particular cortical zones, the number and the volume of adrenocortical cells or the average volume of their cell nuclei. Moreover, we present for the first time a detailed stereological description of adrenal cortex in sows.

Strain differences in rabbit adrenocortical structure and morphological evidence of corticomedullary communication

Interstrain differences in the structure of the mouse and rat adrenal cortex are well known, but related data on rabbits are not available. This study was planned to demonstrate possible strain differences in rabbit adrenal morphology and morphological evidence of a communication between cortex and medulla. For this purpose, the zonation of the adrenal cortex of intact mature male and female rabbits of different strains (New Zealand, Chinchilla and California) were compared using morphometry and the corticomedullary junction was evaluated for close relationship. Marked intersex and interstrain differences were found in the adrenocortical zonation. Female rabbits had larger adrenocortical zones than corresponding males. The rabbits of Chinchilla and California strains had the largest cortical sizes. This difference depended largely upon the higher thickness of the zona fasciculata. Whereas, there were no significant strain differences in the thickness of zona glomerulosa and zona reticularis. Furthermore, examination of corticomedullary junction showed that cortex and medulla were interwoven. Single and small accumulations of cortical cells were spread throughout the medulla. Our morphological data showed the presence of significant interstrain differences in the adrenocortical zonation in the rabbits and provide evidence for a possible paracrine interaction between medullary and cortical cells.

[Effect of selection for behavior of wild gray rats (Rattus norvegicus) on the morphology of the adrenal cortex]

A comparative morphological and functional study of adrenal cortex was conducted in adult male Norway rats selected for domestic and aggressive behavior. Morphological changes were shown to occur in the structure of zona fasciculata of adrenal cortex during selection for domestic behavior.

Morphometric study of the human suprarenal gland in the first postnatal year

The aim of present, study was to describe adrenal volume, volumes of adrenocortical zones, and stroma volume in 40 adrenals obtained from children between 1st and 370th day during autopsy. The postnatal decrease in adrenal volume was caused mainly by rapid fall of fetal zone (FZ) volume (from 70 to 3% of total adrenal volume), that can be divided into two phases: rapid phase (from birth to the end of the second week) and a slow phase from the 3rd week on. Involution was accompanied by increase of zona glomerulosa (ZG) (from 10 to 25% of total adrenal volume), zona fasciculata ZF (from 10 to 38%) and zona reticularis (ZR), volume (from 1 to 23%). During the whole investigated period the volume of medulla remained constant. The volume fraction of stroma (connective tissue and blood vessels) was highest at the beginning of the first postnatal week and then decreased rapidly at the end of the 2nd week, with the most pronounced changes in the fetal zone and medulla. Performed present stereological study confirms opinion that hemorrhagic mechanisms are involved in the involution process of the human fetal zone.

Adrenocortical function in a new world primate, the marmoset monkey, Callithrix jacchus

The function of the adrenal cortex of the marmoset monkey Callithrix jacchus has been investigated. In common with other New World primates, these animals seem to be glucocorticoid resistant. Blood and adrenal glands were obtained from male and female animals under terminal pentobarbitone anesthesia. Dispersed adrenal cell preparations were obtained by treatment with collagenase and incubated with ACTH(1-24), (0.1-1000 nM) angiotensin II (0.1-1000 nM), dibutyryl cyclic AMP (dbcAMP; 30-1000 microM), and forskolin (FSK; 1-30 microM). Plasma cortisol levels (2113 +/- 449 ng/ml male; 3858 +/- 429 ng/ml female) were found to be 10- to 20-fold higher than those quoted for Old World primates and man. The cell preparations showed no significant response to any dose of ACTH tested (0.1-1000 nM), although addition of exogenous precursor (22R-hydroxycholesterol, 2.5 microM) resulted in an increased yield of cortisol and aldosterone. Cyclic AMP production was increased in response to forskolin (1-30 microM) but not ACTH(1-24) (1-1000 nM). In addition, dose-related responses to angiotensin II (maximal stimulation of 316 +/- 49% basal aldosterone at 100 nM angiotensin II), dbcAMP (maximal stimulation of 449 +/- 24% basal cortisol at 300 microM dbcAMP), and forskolin (maximal stimulation of 394 +/- 31% basal cortisol at 10 microM FSK) were obtained. The lack of a response in vitro to ACTH in C. jacchus cannot, therefore, be attributed either to general failure of the cells or to defects in postreceptor signaling mechanisms. The results suggest that there is a reduction in adrenal ACTH receptor number or affinity, with a high basal production rate in vivo maintaining the elevated plasma cortisol levels.

Expression and regulation of melanocortin receptor-5 (MC5-R) in the bovine adrenal cortex

Among the five members of the melanocortin receptor (MC-R) family, MC2 and MC5 are expressed in peripheral tissues. The receptor MC2 (ACTH receptor) almost exclusively expressed in the adrenal cortex whereas MC5-R is expressed in several organs including the adrenal cortex. Both receptors bind ACTH and activate adenylate cyclase. The aim of this work was to study the spatial distribution of MC5-R among the different zones of the bovine adrenal cortex and to analyze the regulation of its expression by its own ligands, ACTH and alpha-MSH and by angiotensin II (AII). Using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and RNase protection assay, MC5-R was detected only in the glomerulosa zone whereas MC2-R was present in both glomerulosa and fasciculata zones of adult adrenal cortex. Treatments by ACTH, alpha-MSH, or AII increased the MC5-R mRNA level in glomerulosa cells by factors 7, 5, and 4.5, respectively. However, although potentially regulated by hormones, MC5-R is expressed at a level at least 100 times less than MC2-R, suggesting that MC5-R expression might only be at trace levels in grown adults, but could be much higher during embryogenesis.

Up-regulation of adrenal cortical and medullary atrial natriuretic peptide and gene expression in rats with deoxycorticosterone acetate-salt treatment

Our previous study demonstrated that human adrenal medulla is a site of atrial natriuretic peptide (ANP) synthesis. To further evaluate the role of adrenal ANP in body fluid homeostasis, we investigated the changes in adrenal ANP in rats receiving deoxycorticosterone acetate (DOCA)-salt treatment. In situ hybridization and immunohistochemical study showed that adrenal ANP messenger RNA (mRNA) and ANP-like immunoreactivities (ANP-LI) were mainly localized in the zona glomerulosa and medulla of vehicle-treated rats. DOCA-salt treatment activated ANP mRNA and peptide expression in all adrenal zones, especially in the zona fasciculata/reticularis from 12 h to the entire 8-day study period. Using a semiquantitative RT-PCR technique, the relative quantities of ANP mRNA in the adrenals of the DOCA-salt-treated group were significantly increased from 1 to 8 days, whereas the adrenal weights of DOCA-salt-treated rats were significantly decreased from day 2 to day 8. Our results are the first to indicate that ANP is synthesized not only in the adrenal medulla but also in the adrenal cortex and their syntheses are markedly increased in DOCA-salt-treated rats. These results imply that adrenal ANP may participate in the intraadrenal regulation of adrenal function on water-electrolyte homeostasis in an autocrine or paracrine manner.

Subcutaneous transplantation of bovine and human adrenocortical cells in collagen gel in scid mice

Adrenocortical cells of bovine origin and of adult and fetal human origin were transplanted subcutaneously (s.c.) in scid mice after being embedded in collagen gel. In this site the cells survived, became vascularized by invasion of host endothelial cells, and secreted steroids into the circulation. The animals' own adrenal glands were removed at the time of cell transplantation. Steroids secreted by the transplants replaced the essential functions of the animals' own adrenal glands. Adrenalectomized animals without transplanted cells died after several days, but most animals with transplanted bovine or adult human adrenocortical cells survived; fewer animals survived with transplanted fetal human adrenocortical cells. The histology of the tissues formed from transplanted cells resembled that of the normal adrenal cortex. A few proliferating cells were observed in tissue from bovine or adult human cells; there was a greater percentage of dividing cells in tissue derived from fetal cells. Subcutaneous transplantation of bovine or human primary adrenocortical cells in collagen provides a model for the study of the physiology, cell biology, and molecular biology of adrenocortical cells in a three-dimensional vascularized tissue structure in a host animal.

Differences in adrenal morphology in male Dark Agouti, Sprague-Dawley and Wistar rats

There is little published information describing the differences in adrenal structure between strains of a single species despite quite well known functional differences. In this paper we report morphological differences in the adrenal glands between three strains of laboratory rat; Dark Agouti (DA), Sprague-Dawley (SD) and Wistar (W). Significant differences in adrenal weights (as a percentage of body weight) were not detected between any of the groups. While there were no significant differences in the volume of medullary or zonae glomerulosa or fasciculata tissue, the volume fraction for the zona reticularis was significantly smaller in DAs compared to the other strains. The functional significance of these differences is unknown. However, it is suggested that the reduced volume of zona reticularis tissue may contribute to a reduced capacity for glucocorticoid synthesis or storage.

Zonal variation in the distribution of an alpha 1-acid glycoprotein glycoform receptor in human adrenal cortex

Using a histochemical technique with three different alpha 1-acid glycoprotein glycoform one glycoform specific receptor has been identified in human adrenal cortex. The receptor is associated to alpha 1-acid glycoprotein glycoform B and alpha 1-acid glycoprotein glycoform C. The glycoform specific receptor was located in the cytoplasm of glomerulosa and outer fasciculata cells. The intensity of the reaction product decreased in the fasciculata, and no staining was seen in inner fasciculata and reticularis. Inhibition with the simple sugars, mannose and GlcNAc confirmed a lectin-like reaction. The binding activity was dependent on the presence of calcium ions and not on thiol reagents. Thus the lectin-like receptor may belong to the C-type lectin family. Using an antibody to alpha 1-acid glycoprotein the presence of alpha 1-acid glycoprotein was observed in the same location as the glycoform specific receptor. The binding of alpha 1-acid glycoprotein glycoform B and alpha 1-acid glycoprotein glycoform C to the glycoform specific receptor is inhibited by the steroid hormones cortisone, aldosterone, estradiol and progesterone but not by testosterone. The pronounced changes in the distribution of AGP and its glycoform receptors during cell differentiation in the adrenal cortex suggest that AGP and its complementary lectins belong to the group of lectins which control differentiation and spatial position.

Effects of ACTH administration on zonation of the guinea pig adrenal cortex

Experiments were done to determine the actions of ACTH on the morphologic and functional characteristics of the zona fasciculata (ZF) and zona reticularis (ZR) in the guinea pig adrenal cortex. In control guinea pigs, a number of morphologic differences distinguished the ZF from the ZR, including the presence of far more lipid in the ZF than in the ZR. Treatment with ACTH decreased the lipid droplet content of the ZF cells, equalizing the amount of lipid in the two zones. Other morphologic differences between the ZF and ZR were also diminished by ACTH treatment. Immunohistochemical analyses indicated that CYP17 protein was found in both the ZF and ZR in control animals, but with greater immunostaining intensity in the ZF. The enzyme protein distribution corresponded with higher 17alpha-hydroxylase activity in the ZF than in the ZR. After ACTH treatment, the intensity of staining and enzyme activities in the two zones were similar, attributable largely to increases in the ZR. In situ hybridization-and immunohistochemistry showed that in control animals CYPD216 was highly expressed in the ZR but not in the ZF. ACTH treatment dramatically reduced the intensity of CYP2D16 mRNA and protein staining in the ZR. Bufuralol 1'-hydroxylase activity, a marker for CYP2D subfamily members, was also decreased significantly in the ZR by ACTH treatment. The data indicate that administration of ACTH to guinea pigs has opposite effects on the expression of CYP17 and CYP2D16 in the ZR, and diminishes or eliminates some of the structural and functional differences between the ZF and ZR. The results suggest a role for ACTH in establishing and maintaining adrenocortical zonation.

Ultrastructural zonation of adrenocortex in the rat

The fine structure of the different zones in the adrenal cortex of the adult rat has been studied under the electron microscope. Four regions mainly differentiated by the mitochondrial morphology, the lipid droplets, and the structure of the ground cytoplasm were recognized. In the glomerular zone mitochondria are thin and elongated with an abundant matrix. The inner structure is characterized by the presence of tubules of 300 A that are straight or bend at an angle and which may be grouped in parallel array giving a pseudocrystalline pattern. The wall of each tubule is a finger-like projection of the inner membrane and its cavity corresponds to the outer chamber of the mitochondrion. In the intermediary zone mitochondria are larger and irregular. The matrix is filled with convoluted tubules and vesicular elements. The lipid droplets are larger and irregular in the glomerulosa and and small in the intermedia. The ground substance is dense and contains free ribosomes in the glomerulosa and starts to be vacuolated in the intermedia. In the fasciculata mitochondria are round or oval and are filled with vesicular elements with a mean size of 450 A. Larger vesicles and more clear elements (vacuoles) are seen near the edge as if their content was diluted. Some of these vacuoles protrude on the surface. In the reticular zone mitochondria are also vesicular but frequently show signs of alteration and disruption. Dense elements recognized as microbodies are observed in the fasciculata but they increase in number in the reticularis. These results are discussed on the light of the so called zonal theory of the adrenal cortex. Two stages in the differentiation of the mitochondria are postulated. The tubular structure of the glomerulosa undergoes a process of disorientation and dilatation of the tubules to form the tubulo-vesicular elements of the intermediary zone. In a second stage of differentiation, by fragmentation of the tubules, the vesicular structure of fasciculata is formed. These findings are discussed from the viewpoint of the relationship between mitochondria and synthesis of steroid hormones. A secretory process that starts within mitochondria by the formation of vesicles and proceeds into the ground cytoplasm, as extruded and more clear vacuoles, is postulated.

Stress-induced morphohistochemical and functional changes in rat adrenal cortex, testis and major salivary glands

The effect of repeated stress (1 h of daily immobilization for seven consecutive days) on the adrenal cortex of young adult male albino rats was evaluated by morphohistochemical methods and plasma assays; at the same time, testes and major salivary glands, as steroid-producing and -depending organs, respectively, were examined. Morphological and histochemical changes were found in the adrenal cortex, testis and submaxillary gland, though varying in degree and extent depending on the gland examined. Corticosterone and progesterone plasma levels increased, in agreement with the lipid depletion observed in the zona fasciculata, while testosterone and androstenedione decreased, as confirmed by the less marked enzymatic activity in the Leydig cells. The study thus proves that repeated stress, even of temporary duration, is able to influence directly or indirectly the morphofunctional state of the three examined glands, suggesting a functional linkage.

Adrenocortical and adrenomedullary homologs in eight species of adult and developing teleosts: morphology, histology, and immunohistochemistry

Morphology, histology, and immunohistochemistry of the adrenocortical and adrenomedullary homologs (adrenal glands) of the following developing and adult teleosts were examined: Salmoniformes-Oncorhynchus mykiss (rainbow trout), Salmo trutta fario (brown trout), Coregonus lavaretus (white fish); Cyprinodontiformes-Gambusia affinis (mosquito fish). Perciformes-Dicentrarchus labrax (sea bass), Sparus aurata (sea bream), Diplodus sargus (white bream), Oblada melanura (saddled bream). The anatomical relationships of the gland with the renal system and venous vessels were also noted. In adults of all species steroidogenic and catecholaminergic chromaffin cells were found in the head kidney, which is pronephric in origin and subsequently transformed into a hematopoietic lymphatic organ. In Perciformes, chromaffin cells are distributed around the anterior and posterior cardinal veins and ducts of Cuvier; in Salmoniformes, around the posterior cardinal veins and in the hematopoietic tissue; and in G. affinis, around the ducts of Cuvier and posterior cardinal veins, while a few are visible also around the sinus venosus. In Perciformes and Salmoniformes, numerous chromaffin cells are also present in the posterior kidney, derived from the opisthonephros, in contact with the caudal vein. Steroidogenic cells are always confined to the head kidney. During development chromaffin and steroidogenic cells appear early after hatching in the pronephric kidney, at the level of the ducts of Cuvier and of the cephalic part of the posterior cardinal veins. Later, chromaffin cells in Perciformes reach the anterior cardinal veins, and subsequently, in both Perciformes and Salmoniformes, they reach the developing posterior kidney. Their localization along the posterior kidney is still in progress about 4 months after hatching and is completed about a year after hatching. These findings support the concept that the structure of the adrenal gland in teleosts is intermediate between that of the other actinopterygians and that of tetrapods. The development differs from that of tetrapods in that it occurs mainly in the pronephros and only later do chromaffin cells reach the opisthonephric kidney.

Aging alters zonation in the adrenal cortex of men

Whereas aging has been shown to be associated with striking reductions in circulating levels of adrenal androgens in humans, the alteration in adrenal function that occurs in aging has not been identified. We sought to determine if there are changes in the zonation of the adrenal in aging men by performing histomorphologic analyses of adrenal specimens that had been obtained at autopsy following sudden death due to trauma. We evaluated adrenals from 21 young men (20-29 yrs) and 12 older men (54-90 yrs); inclusion criteria required the presence of medullary tissue in the specimen and fixation within the first 24 hrs postmortem. Sections stained with H/E were examined microscopically and areas of the cortex that included adjacent medullary tissue were chosen for quantitative evaluation by use of a computerized image analysis system. The average width (arbitrary units, pixels) of the zona reticularis and that of the combined zonae fasciculata/glomerulosa were determined from sections stained for reticulum fibers. The zona reticularis represented 37.1 +/- 1.9% of the total cortical width in the young men, which was significantly greater than that of the older men (27.1 +/- 3.3%, P = 0.0082). The zona fasciculata/glomerulosa to zona reticularis ratio in the young men (1.84 +/- 0.15) was significantly less that that of the older men (3.29 +/- 0.47, P = 0.0011). There was no significant difference in the total width of the cortex in young compared to older men. These data suggest that aging results in alterations within the cortex of the adrenals in men such that there is a reduction in the size of the zona reticularis and a relative increase in the outer cortical zones. A reduced mass of the zona reticularis could be responsible for the diminished production of dehydroepiandrosterone and dehydroepiandrosterone sulfate that occurs during aging.

Preclinical Cushing's syndrome due to adrenocorticotropin-independent bilateral adrenocortical macronodular hyperplasia with concurrent excess of gluco- and mineralocorticoids

A 48-year-old with bilateral adrenal incidentalomas was studied. Although the serum cortisol level was normal, autonomous cortisol secretion was shown by the loss of diurnal rhythm, no suppressibility by dexamethasone, and complete suppression of plasma adrenocorticotropin levels. Imaging analyses revealed bilateral adrenal masses, showing isotope uptake. He was diagnosed as preclinical Cushing's syndrome due to adrenocorticotropin-independent bilateral adrenocortical macronodular hyperplasia, confirmed histologically. Despite the undetectable plasma adrenocorticotropin level and renin activity, serum mineralocorticoids levels were not suppressed, which were decreased after subtotal adrenalectomy. It was suggested that hyperplastic adrenal glands could produce both gluco- and mineralocorticoids concomitantly.

Effects of pneumadin (PNM) on the adrenal glands. 6. Further studies on the inhibitory effect of PNM on dexamethasone-induced atrophy of the rat adrenal cortex

Pneumadin (PNM) is a biologically active decapeptide, which has previously been found to enhanced rat adrenal growth; the mechanism is indirect and probably involves the stimulation of both arginine-vasopressin (AVP) and ACTH release. The effects of 2- and 6-day PNM administration on the atrophic adrenal cortices of rats treated for 8 and 12 days, respectively, with daily subcutaneous injections of 15 or 40 g/100 g body weight of dexamethasone (Dx) were investigated. Morphometry showed that PNM counteracted Dx-induced adrenal atrophy, by preventing the decrease in volume and number of the parenchymal cells. PNM raised aldosterone and corticosterone production of adrenal quarters from Dx-treated rats, but it did not evoke significant changes in the plasma concentrations of the two hormones. The preventive effect of PNM was only partial and almost exclusively evident in rats administered the lower dose of Dx. In light of these findings the following conclusions are drawn: (i) PNM is able to partially overcome the Dx-induced inhibition of the rat hypothalamo-pituitary-adrenal axis, probably by stimulating the pituitary release of AVP and ACTH, that in turn enhance adrenocortical growth; (ii) the PNM-induced improvement of the secretory capacity of atrophic adrenocortical cells is not sufficient to raise the blood level of corticosteroid hormones; and (iii) Dx exerts a direct inhibitory action on adrenocortical cells, which is not counteracted by PNM.

Vascularization of the adrenal cortex: its possible involvement in the regulation of steroid hormone release

This review examines the morphology of the adrenal gland with particular reference to the adrenal vasculature. It examines the possibility that variability in adrenal gland responsiveness may be attributable to neural or hormonal modulation of adrenal blood flow. Changes in the rate of blood flow through the adrenal cortex would be expected to play an important role in the regulation of steroid hormone release. It would affect both the delivery of the major stimulant (ACTH) and the removal of the end product from the steroidogenic cells (the glucocorticoids). In the past, interest in this area has concentrated on the regulation of arterial blood flow, rather than the regulation of venous drainage. The current review examines the concept of vascular damming, and attempts to link the morphological features of the gland with experimental data associated with glucocorticoid release. It is postulated that regulation of venous drainage, via the vascular dam, plays an important role in the storage of the secretory product during the animals' inactive phase, and in the initial rapid rise in plasma levels of the glucocorticoids seen in response to stress or injection of ACTH.

Zona glomerulosa-specific factor: cloning and function

The rat adrenal cortex is composed of three zones: the zona glomerulosa, the zona fasciculata, and the zona reticularis. Several investigators have claimed the presence of a zona intermedia between the zonae glomerulosa and fasciculata. The cells of zona glomerulosa, a few layers of cells just beneath the adrenal capsule, synthesize and secrete aldosterone, whereas those of zonae fasciculata and reticularis secrete glucocorticoids and androgens, respectively. The function of the cells in zona intermedia is unclear, because they express neither aldosterone synthase nor 11 beta-hydroxylase. To investigate the mechanism underlying the zonal differentiation of adrenocortical steroidogenesis, attempts have been made to isolate and characterize zone-specifically expressed proteins such as steroidogenic enzymes and putative regulatory factors. Having subtracted the mRNAs present in the decapsulated adrenal gland from those in the adrenal capsule, we successfully isolated three distinct clones, each specifically expressed in the zona glomerulosa. One clone encoded a protein named zona glomerulosa-specific factor (ZOG), which had a putative signal peptide at the N-terminus, six tandem epidermal growth factor (EGF)-like repeats, and a transmembrane domain in the central portion and a short cytosolic stretch at the C-terminus. Immunohistochemical studies using the antibody raised against ZOG confirmed the presence of the protein in all layers of cells in the zona glomerulosa. In contrast, cells possessing aldosterone synthase were present only in the periphery of zona glomerulosa, just beneath the capsule. These findings suggest that there are at least two kinds of zona glomerulosa cells in the rat adrenal cortex, one expressing aldosterone synthase as well as ZOG, and another expressing only ZOG. The cells in the zona intermedia did not express ZOG, aldosterone synthase, or 11 beta-hydroxylase, but did express Ad4BP. ZOG was not detected in zonae fasciculata and reticularis where 11 beta-hydroxylase was present.

The non-neurogenic catecholamine response of the fetal adrenal to hypoxia is dependent on activation of voltage sensitive Ca2+ channels

We have investigated the cellular mechanisms underlying the catecholamine response of the fetal sheep adrenal to hypoxia before and after the development of adrenal innervation. Adrenals were collected before (80-100 days gestation: n = 7) and after (135-146 days gestation: n = 10) development of innervation and retrogradely perfused with oxygenated Krebs bicarbonate buffer in vitro via the renal vein. Adrenal hypoxia was induced by perfusion with hypoxic Krebs buffer (pO2 = 46.7 +/- 2.4 mm Hg) for 30 min periods in the presence and absence of hexamethonium (500 microM), Ca2+ (2.5 mM), nifedipine (1 microM) and KCl (10 mM). Hypoxia stimulated an increase (P < 0.001) in the output of noradrenaline at 80-100 days (3 min pre hypoxia, 0.18 +/- 0.07 nmol/3 min; 20 min hypoxia, 0.74 +/- 0.22 nmol/3 min) and at 135-146 days (3 min pre hypoxia, 0.53 +/- 0.20 nmol/3 min; 20 min hypoxia, 1.71 +/- 0.85 nmol/3 min). Adrenaline output was also higher (P < 0.001) than basal values (80-100 days, 0.11 +/- 0.06 nmol/3 min; 135-146 days, 0.53 +/- 0.15 nmol/3 min) after 20 min hypoxia (0.41 +/- 0.20 nmol/3 min and 1.35 +/- 0.56 nmol/3 min respectively). The catecholamine responses to hypoxia were abolished by removal of Ca2+ from the adrenal perfusate. There was a reduction (P < 0.05) in the catecholamine secretory response to hypoxia in the presence of nifedipine. Noradrenaline output decreased from 4.33 +/- 0.84 nmol/30 min to 0.16 +/- 0.49 nmol/30 min and adrenaline output decreased from 3.16 +/- 1.66 nmol/30 min to -0.01 +/- 0.24 nmol/30 min in the presence of nifedipine. The fetal adrenal secretes catecholamines by a direct or non-neurogenic mechanism in response to hypoxia. This secretory response is dependent on the activation of voltage sensitive Ca2+ channels in the chromaffin cell membrane.

Genetic regulation of border zone formation in female mastomys (Praomys coucha) adrenal cortex

The unique border zone between the zona fasciculata and z. reticularis of the female adrenal cortex is formed in the wild-colored inbred mastomys (Praomys coucha) strain, MWC, but never in the chamois-colored inbred strain, MCC. This clear strain-specific trait was genetically analyzed using F1, F2, and backcross progenies produced between MWC and MCC. Reciprocal crosses gave no significant differences in the phenotypic ratio of F1 or F2 progeny. Border zone formation was detected in 0% of F1 females, 25.8% of F2 females, 0% of backcross females between F1 and MCC, and 47.7% of backcross females between F1 and MWC. From these results, it was concluded that border zone formation in the female MWC adrenal is regulated by a single autosomal recessive gene and this gene was named bzf (border zone formation).

The T/ebp null mouse: thyroid-specific enhancer-binding protein is essential for the organogenesis of the thyroid, lung, ventral forebrain, and pituitary

The thyroid-specific enhancer-binding protein (T/ebp) gene was disrupted by homologous recombination in embryonic stem cells to generate mice lacking T/EBP expression. Heterozygous animals developed normally, whereas mice homozygous for the disrupted gene were born dead and lacked the lung parenchyma. Instead, they had a rudimentary bronchial tree associated with an abnormal epithelium in their pleural cavities. Furthermore, the homozygous mice had no thyroid gland but had a normal parathyroid. In addition, extensive defects were found in the brain of the homozygous mice, especially in the ventral region of the forebrain. The entire pituitary, including the anterior, intermediate, and posterior pituitary, was also missing. In situ hybridization showed that the T/ebp gene is expressed in the normal thyroid, lung bronchial epithelium, and specific areas of the forebrain during early embryogenesis. These results establish that the expression of T/EBP, a transcription factor known to control thyroid-specific gene transcription, is also essential for organogenesis of the thyroid, lung, ventral forebrain, and pituitary.

Effects of oxytocin on the function and morphology of the rat adrenal cortex: in vitro and in vivo investigations

The effects of oxytocin (OX) on the function and morphology of the rat adrenal cortex were studied in vivo and in vitro. OX exerted a potent stimulatory action on basal, but not 10(-8) M ACTH-stimulated corticosterone (B) secretion of dispersed rat inner (zona fasciculata and zona reticularis) adrenocortical cells (maximal effective concentration: 10(-9) M); in contrast, at higher concentrations (10(-7)/10(-6) M) OX inhibited maximally ACTH-stimulated B output. A single subcutaneous (s.c.) injection of 1.2 nmol/100 g body weight OX resulted in a long-lasting (up to 12 h) rise in plasma B concentration (PBC). The prolonged administration of OX (daily s.c. injections of 0.6 or 1.2 nmol/100 g for 10 days) caused a marked lowering in the adrenal weight and volume of all adrenocortical zones, that in turn was due to a decrease in the number of their parenchymal cells; however, the average volume of inner adrenocortical cells was significantly increased. Basal PBC was lowered, but its response to ether stress was unchanged in comparison with control rats. Prolonged OX treatment did not change B secretion by adrenal slices, but it markedly raised that of dispersed inner adrenocortical cells. Our present findings clearly show that the effects of OX on the adrenal cortex depend on the experimental model employed (in vitro versus in vivo) and the duration of treatment (acute versus chronic). Taken together they allow us to conclude that OX exerts an acute direct stimulatory effect on the rat adrenal cortex, and a chronic inhibitory one, that at least in part could be due to the interference of OX with the mechanism(s) of intracellular transduction of the ACTH secretagogue signal.

Comparison of adrenocortical zonation in C57BL/6J and DDD mice

Adrenal weights and adrenocortical zonation were compared in two inbred mouse strains, C57BL/6J and DDD, which are different in both origin and genetic background. Clear strain and sex differences were observed in the adrenal weight and the morphology of the zona fasciculata, z. reticularis and X zone. DDD adrenals were larger than C57BL/6J ones regardless of sex. The z. fasciculata was thicker in female than male DDD mice. The z. reticularis of DDD males developed nodules at 70 days of age, followed by an increase in size with age, while that of C57BL/6J males did not. Parous females experiencing pregnancy, gestation and lactation also developed similar nodules, but virgins did not. The X zone degeneration occurred earlier in males than in females. This zone disappeared before 5 weeks of age in males but gradually decreased in thickness with age in DDD virgins. The female X zone was thicker and degenerated with vacuolation in DDD, while it was thinner and degenerated without vacuolation in C57BL/6J. Such clear strain differences in the inner cortices, z. reticularis and X zone, suggested that their morphology might be regulated primarily by genetics and modified by endocrinology.

Strain difference of the adrenal cortex between A/J and SM/J mice, progenitors of SMXA recombinant inbred group

The recombinant inbred (RI) mouse group is useful for genetic analysis of a phenotype which is regulated by multiple loci. The female adrenal cortex was compared histologically to detect the strain differences between A/J and SM/J for the purpose of genetic analysis of adrenocortical morphogenesis using the SMXA RI group constructed between A/J and SM/J. Clear morphological differences were found in the zona reticularis and X zone in addition to the significantly small body and adrenal weights in SM/J. The z. reticularis was markedly thicker in SM/J than in A/J and the X zone was constituted of vacuolated cells in A/J and non-vacuolated cells in SM/J. The genetic control of these morphological traits was analyzed using SMXA RI strains. The results suggest that the thickness of the z. reticularis may be controlled by single locus and that vacuolation of the X zone by 3 different loci between A/J and SM/J.

Adrenocortical zonation in chamois-coloured mastomys, Praomys coucha

Body and adrenal weights, and histology of the adrenal cortex were examined in the chamois-coloured mastomys (Praomys coucha) at inbred generations 3 to 10. Body and adrenal weights were consistently larger in males than in females, although the adrenal to body weight ratios tended to be lower before 50 days of age and were clearly higher after. Distinct sex differences were found in the adrenal cortex. The whole cortex and the zona reticularis were thicker in males and the zona reticularis became thicker in males, but thinner in females with age. The border zone characteristics of females of the wild-coloured mastomys strain, was not formed in the chamois-coloured strain. This was a very unique, interesting strain difference. Comparative studies of both strains may contribute to elucidation of the mechanism of border zone formation in the mastomys adrenal cortex.

Hyperadrenocorticism, attenuated inflammation, and the life-prolonging action of food restriction in mice

Food restriction (FR), which extends life span, is associated with an enhanced diurnal elevation of glucocorticoids. This increase in glucocorticoids may contribute to longevity by chronically enhancing the same protective mechanisms mobilized during acute stress. The objective of this study was to determine if attenuation of inflammation, a presumably protective effect of glucocorticoids, occurs in FR mice. Two-month-old male BALB/c mice were either fed ad lib (AL) or FR (60% AL calories) for 2 months. After one month, the diurnal elevation of plasma corticosterone was threefold higher in FR mice. Two weeks after corticosterone sampling, a hind foot pad of each mouse was injected with 20 microliters of 4% carrageenan. Maximum observed edema did not differ between FR and AL groups, but edema was reduced at onset and fell earlier in FR mice. Results indicate that at least one inflammatory reaction is attenuated by FR and are consistent with the hypothesis that FR enhances a potentially protective glucocorticoid activity.

Hypothalamic-pituitary-adrenocortical axis changes in the rat after long-term treatment with the reversible monoamine oxidase-A inhibitor moclobemide

The effects of the reversible monoamine oxidaseA (MAOA) inhibitor moclobemide on the rat hypothalamic-pituitary-adrenocortical (HPA) axis were studied. The time-course experiments showed that moclobemide, given via the drinking water (4.5 mg/kg/day), produces significant decreases (p < 0.05) in adrenal weight after 5 (-23%) and 7 weeks (-16%) of treatment. It was found that long-term moclobemide treatment had neuroanatomically distinct effects on corticosteroid receptor expression. Hippocampal mineralocorticoid receptor (MR) levels were upregulated at 2 (+65%), 5 (+76%) and 7 (+19%) weeks of treatment. Glucocorticoid receptor (GR) levels in this limbic brain structure were slightly up-regulated by 10% at 5 weeks, and indistinguishable from controls after 2 and 7 weeks of treatment. After 5 weeks of treatment, MR levels were unchanged in the hypothalamus, and increased by 44, 24 and 28% in the neocortex, amygdala and anterior pituitary, respectively. GR concentrations were elevated by 24 and 14% in the hypothalamus and anterior pituitary, respectively, whereas neocortical and amygdaloid receptor levels were not altered. After 5 weeks of moclobemide treatment, marked decreases in [125I]Tyr0-ovine corticotropin-releasing hormone ([125I])-oCRH binding capacity and proopiomelanocortin (POMC) mRNA content were observed in the anterior pituitary. Regarding the functional implications of long-term anti-depressant treatment, moclobemide treatment (5 weeks, 4.5 mg/kg/day) significantly attenuated stress (30-min novel environment)-induced plasma ACTH (-35%) and corticosterone (-29%) levels; no changes were observed in basal plasma ACTH and corticosterone levels. In conclusion, this study shows that moclobemide has a concerted influence on multiple elements of the HPA axis manifesting functionally as a reduced neuroendocrine responsiveness to stress. In previous experiments, it was found that the structurally and pharmacologically distinct antidepressant amitriptyline after long-term administration also attenuated HPA axis activity. We postulate that an adjustement of HPA axis activity may be regarded as a common denominator for clinically efficacious antidepressant drugs.

Pharmacological characterization and autoradiographic localization of dopamine receptors in the human adrenal cortex

The pharmacological characteristics and the anatomical localization of dopamine D1-like and D2-like receptors were studied in sections of the human adrenal cortex using radioligand binding and autoradiographic techniques. [3H]SCH 23390 was used as a ligand of D1-like receptors, whereas [3H]spiroperidol was used to label D2-like receptors. No specific [3H]SCH 23390 binding was detectable in sections of the human adrenal cortex. On the other hand, [3H]spiroperidol was bound to sections of the adrenal gland in a manner consistent with the labelling of dopamine D2-like receptor sites. The binding was time, temperature and concentration dependent, belonging in the range of concentrations of the radioligand used for a single class of high-affinity sites. The dissociation constant (Kd) averaged 2.7 nmol/l, whereas the maximum density of binding sites (Bmax) was 160 nmol/mg tissue. Experiments on the pharmacological specificity of [3H]spiroperidol binding to sections of the human adrenal cortex revealed that clozapine was the most powerful displacer of [3H]spiroperidol from sections of the human adrenal cortex. This suggests the presence in the human adrenal cortex of dopamine receptors of the D4 subtype. Light microscope autoradiography showed the highest density of specific [3H]spiroperidol binding sites in the zona glomerulosa and to a lesser extent in the zona reticularis. Only sparse [3H]spiroperidol binding sites were localized in the zona fasciculata. The possible functional consequences of this localization of dopamine D2-like receptor sites in the human adrenal cortex are discussed.