Expression of adrenomedullin 2/intermedin in human adrenal tumors and attached non-neoplastic adrenal tissues

Adrenomedullin 2/intermedin (AM2/IMD) is a new member of calcitonin/calcitonin gene-related peptide family. AM is expressed in various tumors including adrenocortical tumors and modulates tumor growth. The AM2/IMD expression has not been studied, however, in adrenal tumors. The expression of AM2/IMD and AM was therefore studied in human adrenal tumors and attached non-neoplastic adrenal tissues by immunocytochemistry (ICC). Immunoreactive (IR)-AM2/IMD was measured by RIA. Furthermore, the expression of AM2/IMD and its receptor components, calcitonin receptor-like receptor (CRLR), and receptor activity-modifying proteins (RAMPs) 1, 2, and 3 mRNA in these tissues was studied by reverse transcription PCR (RT-PCR). ICC showed that AM2/IMD and AM immunoreactivities were localized in adrenocortical tumors and pheochromocytomas. AM2/IMD and AM immunoreactivities were detected in medulla of attached non-neoplastic tissues, while the degree of immunoreactivity for AM2/IMD and AM in cortices of attached adrenals was relatively weak or undetectable. RIA detected IR-AM2/IMD in adrenal tumors (0.414+/-0.12 to 0.786+/-0.27 pmol/g wet weight, mean+/-S.E.M.) and attached adrenal tissues (0.397+/-0.052 pmol/g wet weight). Reverse-phase high-performance liquid chromatography showed one broad peak eluted in the similar position to synthetic AM2/IMD with several minor peaks. RT-PCR showed expression of AM2/IMD, CRLR, and RAMP1, RAMP2, and RAMP3 mRNA in tissues of adrenal tumors and attached adrenal glands. In conclusion, AM2/IMD is expressed in human adrenal tumors and attached non-neoplastic adrenal tissues and may play (patho-)physiological roles in normal and neoplastic adrenals as an autocrine/paracrine regulator.

Changes in vasotocin immunoreactivity of paraventricular nuclei and adrenal function of Japanese quail in relation to different phases of sexual development

In relevance to osmoregulatory and reproductive functions, activity of hypothalamic neurosecretory neurons may also vary seasonally. The current study was performed to determine annual changes in ir-AVT neurons of hypothalamus and adrenal gland function. We examined changes in ir-AVT neuron by immunohistochemical method and plasma testosterone was measured by enzyme immunoassay. The steroidogenic interrenal activity was studied by histological and biochemical methods. Birds were sampled in February (quiescent), April (recrudescent), June (breeding) and November (regressive). A significant and gradual increase in the number of ir-AVT neurons was observed from quiescent to breeding phase which decreased during regressive phase of annual gonadal cycle. The gradual increase in ir-AVT neurons along with annual gonadal activity of quail were accompanied by increase in plasma levels of testosterone. These results indicate a functional interaction between sex steroid and AVT synthesizing neurons. Adrenal activity (as judged by weight, ascorbic acid content, cortical cord width and cortico-medullary ratio) was also maximum during breeding phase. It is thus postulated that domesticated quail when exposed to natural day length (NDL), exhibits seasonal/annual cyclicity in vastocinergic activity and adrenal function which may be due to difference in sex steroid hormone.

Production and application of a polyclonal peptide antiserum for universal detection of StAR protein

We report production of a polyclonal antibody against the StAR (steroidogenic acute regulatory) protein of steroidogenic cells and immunohistochemistry (IHC) staining of bovine adrenal gland tissue available in paraffin block. The epitope-specific polyclonal antibody was produced in a rabbit immunized against a synthetic 26 amino acid peptide (82AMQRALGILKDQEGWKKESRANGDE107) derived from the coding sequences reported for the bovine StAR gene (Gene Bank Accession No. Q28918). Western blots were developed using the StAR-specific peptide antiserum with an alkaline-phosphatase-conjugated anti-rabbit IgG second antibody chromogenic system. The antiserum was found to be highly specific for StAR, which exhibited an estimated molecular weight of about 30 KDa for all species analyzed. Finally, the peptide antiserum was successfully employed to localize StAR protein by immunohistochemical staining of thin sections prepared from bovine adrenal gland tissue. This study is the first to report a polyclonal peptide antiserum that apparently recognizes native StAR protein, regardless of the species of origin. The successful production of the antibody has provided a useful tool for studying regulation of StAR protein.

Expression of vasopressin receptors in ACTH-independent macronodular bilateral adrenal hyperplasia causing Cushing's syndrome: molecular, immunohistochemical and pharmacological correlates

Cortisol secretion in ACTH-independent macronodular adrenal hyperplasia (AIMAH) causing Cushing's syndrome can be controlled by illegitimate receptors. The aim of the present study was to characterize the molecular, immunohistochemical, and pharmacological profiles of vasopressin receptors in cells derived from three patients with AIMAH (H1-H3), in order to evaluate the role of ectopic vasopressin receptors in the physiopathology of hypercortisolism. Expression of mRNAs encoding the vasopressin receptor types (V(1a), V(1b), and V(2)) were analyzed by RT-PCR in adrenal tissues. The presence of V(1a) and V(2) receptors was studied by immunohistochemistry on adrenal sections. The pharmacological profiles of vasopressin receptors involved in the control of cortisol secretion were investigated using the V(1a) receptor antagonist SR49059 and the V(2) receptor agonist [deamino-Cys(1), Val(4), D-Arg(8)]-vasopressin on cultured cells. The V(1a) receptor protein was present and functional in H1 and H3 tissues, whereas the V(1b) receptor was not expressed in any of the tissues. RT-PCR experiments revealed that V(2) receptor mRNAs were detected in the three tissues. In contrast, immunohistochemical and cell incubation studies showed that the V(2) receptor was involved in the stimulatory effect of AVP on cortisol secretion in H1 and H2, but not in H3 cells. Taken together, these data show that expression of functional ectopic V(2) receptors and repression of eutopic V(1a) receptor can coexist in some hyperplastic corticosteroidogenic tissues. They also reveal that immunohistochemical and incubation studies are essential for the characterization of ectopic receptors actually involved in the control of cortisol secretion by AIMAHs.

Chronic consumption of a low-fat diet leads to increased hypothalamic agouti-related protein and reduced leptin

OBJECTIVE

This study examined the hypothesis that dietary fat under ad libitum feeding conditions influences expression levels (mRNA) of the mouse agouti-related protein (AgRP), leptin, leptin receptor (OBRb), and neuropeptide Y (NPY) at early stages of development.

METHODS

C57Bl/6J male mice were placed on a high-fat diet (HFD) or a low-fat diet (LFD) shortly after weaning. Groups of mice were euthanized at various ages and real-time one-step reverse transcriptase polymerase chain reaction was used to analyze gene expression in the hypothalamus (AgRP, NPY, OBRb), the adrenal gland (AgRP), the testis (AgRP), and epididymal fat (leptin).

RESULTS

Leptin expression increased linearly with age but only under the HFD despite body weight gain under both diets. This pattern of expression coincided with reduced expression of hypothalamic AgRP under an HFD, whereas OBRb and NPY did not fluctuate in response to diet. By contrast, consumption of an LFD (i.e., high carbohydrate) increased hypothalamic AgRP and suppressed adipose leptin, which is consistent with the notion that leptin could regulate AgRP centrally. In contrast, AgRP expression in the adrenal gland initially decreased and then increased with age under both diets.

CONCLUSIONS

Dietary fat can have a tissue-dependent effect on AgRP that may be unfettered by leptin under an HFD.

Simultaneous analysis of angiotensin peptides by LC-MS and LC-MS/MS: metabolism by bovine adrenal endothelial cells

Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were developed to simultaneously determine the concentrations of angiotensin (Ang) II, Ang 1-7, Ang III, and Ang IV in biological samples. The samples were extracted with C18 solid-phase extraction cartridges and separated by a reverse-phase C18 column using acetonitrile in water with 0.1% formic acid as a mobile phase. Ang peptides were ionized by electrospray and detected by triple quadrupole MS in the positive ion mode. (M+3H)(3+) and (M+2H)(2+) ions were chosen as the detected ions in the single ion recording (SIR) mode for LC-MS. The limits of detection (signal/noise [S/N]=3) using SIR are 1 pg for Ang IV and 5 pg for Ang 1-7, Ang III, and Ang II. Multiple reaction monitoring (MRM) mode was used for LC-MS/MS. The limits of detection (S/N =3) using MRM are 20 pg for Ang IV and 25 pg for Ang 1-7, Ang III, and Ang II. These methods were applied to analyze Ang peptides in bovine adrenal microvascular endothelial cells. The results show that Ang II is metabolized by endothelial cells to Ang 1-7, Ang III, and Ang IV, with Ang 1-7 being the major metabolite.

Growth analysis of the mouse adrenal gland from weaning to adulthood: time- and gender-dependent alterations of cell size and number in the cortical compartment

The adrenal gland is of critical importance for a plethora of biological processes. We performed the first systematic analysis of adrenal gland growth using unbiased stereological methods in male and female mice from weaning to adulthood (weeks 3, 5, 7, 9, and 11) at the organ, compartment, and cellular levels. Adrenal weights increased from week 3 to week 7 in male and female mice, remained at this level in females, but decreased by 25% between week 7 and week 9 in males. Female adrenal glands displayed a higher weight at any stage investigated. The volume of the zona fasciculata was consistently higher in female vs. male mice. In both genders, the number of zona fasciculata cells reached a maximum at the age of 7 wk and decreased significantly until week 9. Serum corticosterone concentrations decreased from 3 to 11 wk of age both in male and female mice. However, the estimated total amounts of corticosterone in the circulation were similar in 3- and 11-wk-old mice. Furthermore, total circulating corticosterone was higher in females than in males at an age of 5 and 11 wk. In the zona glomerulosa and in the X-zone, time- and gender-dependent growth effects were observed. In conclusion, our results demonstrate that growth and function of the adrenal glands are markedly influenced by gender and age. These factors require careful consideration in studies aiming at the functional dissection of genetic and environmental factors affecting adrenal growth and function.

Expression of extracellular matrix proteins and integrins in rat adrenal gland: importance for ACTH-associated functions

The expression of main extracellular matrix (ECM) and their integrins were studied in the adult rat adrenal gland. Collagen I, IV (CI, CIV), laminin (LN) and fibronectin (FN) expression was observed surrounding each glomerulosa cell and as long fibrils between the cords of fasciculata cells. In the medulla, FN was present around chromaffin cells or bordering blood vessels. Integrin alpha2, alpha3 and alpha5 were present mainly in the cortex, while alpha1 was present in the medulla. In culture, all ECM favoured proliferation of both glomerulosa and fasciculata cells, while protein synthesis was lower on FN and LN in glomerulosa cells. CIV promoted ACTH-induced proliferation whereas FN favoured ACTH-induced protein synthesis in glomerulosa cells. Except for LN, ECM increased expression of 3beta-hydroxysteroid dehydrogenase and enhanced basal aldosterone, although corticosterone secretion was only enhanced by CI and CIV. In fasciculata cells, the potency of ACTH-induced cAMP production was lower on ECM, compared with plastic. Moreover, ACTH, but not ECM, activated mitogenic-activated protein kinase p38 and stress-activated protein kinases. Glomerulosa and fasciculata cells grown on CI and CIV had a polygonal morphology, while cells grown on LN appeared as clusters of small rounded cells. On FN, the glomerulosa cells exhibited polygonal morphology while fasciculata cells appeared as clusters of small rounded cells. Together, these results indicate that ECM modulates basal and ACTH-induced cell functions, with FN, CI and CIV specifically favouring steroid secretion, as opposed to LN which inhibits secretion while promoting proliferation.

In Vivo Imaging of Farnesoid X Receptor Activity Reveals the Ileum as the Primary Bile Acid Signaling Tissue

We generated and characterized a firefly luciferase reporter mouse for the nuclear receptor farnesoid X receptor (FXR). This FXR reporter mouse has basal luciferase expression in the terminal ileum, an organ with well-characterized FXRalpha signaling. In vivo luciferase activity reflected the diurnal activity pattern of the mouse, and is regulated by both natural (bile acids, chenodeoxycholic acid) and synthetic (GW4064) FXRalpha ligands. Moreover, in vivo and in vitro analysis showed luciferase activity after GW4064 administration in the liver, kidney, and adrenal gland, indicating that FXRalpha signaling is functional in these tissues. Hepatic luciferase activity was robustly induced in cholestatic mice, showing that FXRalpha signaling pathways are activated in this disease. In conclusion, we have developed an FXR reporter mouse that is useful to monitor FXRalpha signaling in vivo in health and disease. The use of this animal could facilitate the development of new therapeutic compounds that target FXRalpha in a tissue-specific manner.

Corticotropin-releasing factor (CRF) and CRF-binding protein expression in and release from the head kidney of common carp: evolutionary conservation of the adrenal CRF system

Corticotropin-releasing factor (CRF) plays a central role in the regulation of the stress axis. In mammals, CRF as well as its receptors and its CRF-binding protein (CRF-BP) are expressed in a variety of organs and tissues outside the central nervous system. One of these extrahypothalamic sites is the adrenal gland, where the paracrine actions of adrenal CRF influence cortical steroidogenesis and adrenal blood flow. Although the central role of CRF signaling in the initiation and regulation of the stress response has now been established throughout vertebrates, information about the possible peripheral presence of CRF in earlier vertebrate lineages is scant. We established the expression of CRF, CRF-BP, and the CRF receptor 1 in a panel of peripheral organs of common carp (Cyprinus carpio). Out of all the peripheral organs tested, CRF and CRF-BP are most abundantly expressed in the carp head kidney, the fish equivalent of the mammalian adrenal gland. This expression localizes to chromaffin cells. Furthermore, detectable quantities of CRF are released from the intact head kidney following in vitro stimulation with 8-bromo-cAMP in a superfusion setup. The presence of CRF and CRF-BP within the chromaffin compartment of the head kidney suggests that a pathway homologous to the mammalian intra-adrenal CRF system is present in the head kidney of fish. It follows that such a system to locally fine-tune the outcome of the centrally initiated stress response has been an integral part of the vertebrate endocrine system since the common ancestor of teleostean fishes and mammals.

Prions in the peripheral nerves of bovine spongiform encephalopathy-affected cattle

With the use of increasingly sensitive methods for detection of the abnormal isoform of prion protein (PrPSc) and infectivity in prion diseases, it has recently been shown that parts of the peripheral nervous system (PNS) of bovine spongiform encephalopathy (BSE)-affected cattle may become infected. It has been reported that prions spread to the central nervous system (CNS) via the PNS in sheep scrapie, but the pathogenesis of BSE in cattle is less well understood. To determine whether parts of the PNS other than those implicated directly in the hypothetical pathogenetic spread of agent from the intestine to the CNS become involved before or after the CNS is affected, PrPSc distribution was investigated by a highly sensitive Western blotting technique in dorsal root ganglia, stellate ganglion, phrenic, radial and sciatic nerves, adrenal gland and CNS of cattle that were inoculated orally with BSE-affected brain and culled sequentially. In experimentally BSE-affected cattle, PrPSc was first detected in the CNS and dorsal root ganglia; subsequently, PrPSc accumulation was detected in the peripheral nerve trunks. PrPSc was also detected in the adrenal glands of cattle that showed clinical signs. No PrPSc was detected in the PNS of BSE-negative cattle. This study shows that, with respect to dorsal root ganglia, a paravertebral sympathetic ganglion and the somatic nerves examined, PrPSc is detected in the PNS during the disease course at the same time as, or after, it accumulates in the CNS.

On-chip amperometric measurement of quantal catecholamine release using transparent indium tin oxide electrodes

Carbon-fiber amperometry has been extensively used to monitor the time course of catecholamine release from cells as individual secretory granules discharge their contents during the process of quantal exocytosis, but microfabricated devices offer the promise of higher throughput. Here we report development of a microchip device that uses transparent indium tin oxide (ITO) electrodes to measure quantal exocytosis from cells in microfluidic channels. ITO films on a glass substrate were patterned as 20-mum-wide stripes using photolithography and wet etching and then coated with polylysine to facilitate cell adherence. Microfluidic channels (100 mum wide by 100 mum deep) were formed by molding poly(dimethylsiloxane) (PDMS) on photoresist and then reversibly sealing the PDMS slab to the ITO-glass substrate. Bovine adrenal chromaffin cells were loaded into the microfluidic channel and adhered to the ITO electrodes. Cells were stimulated to secrete by perfusing a depolarizing "high-K" solution while monitoring oxidation of catecholamines on the ITO electrode beneath the cell using amperometry. Amperometric spikes with charges ranging from 0.1 to 1.5 pC were recorded with a signal-to-noise ratio comparable to that of carbon-fiber electrodes. Further development of this approach will enable high-throughput measurement of quantal catecholamine release simultaneously with optical cell measurements such as fluorescence.

Genomic and expression analysis of multiple Sry loci from a single Rattus norvegicus Y chromosome

Background

Sry is a gene known to be essential for testis determination but is also transcribed in adult male tissues. The laboratory rat, Rattus norvegicus, has multiple Y chromosome copies of Sry while most mammals have only a single copy. DNA sequence comparisons with other rodents with multiple Sry copies are inconsistent in divergence patterns and functionality of the multiple copies. To address hypotheses of divergence, gene conversion and functional constraints, we sequenced Sry loci from a single R. norvegicus Y chromosome from the Spontaneously Hypertensive Rat strain (SHR) and analyzed DNA sequences for homology among copies. Next, to determine whether all copies of Sry are expressed, we developed a modification of the fluorescent marked capillary electrophoresis method to generate three different sized amplification products to identify Sry copies. We applied this fragment analysis method to both genomic DNA and cDNA prepared from mRNA from testis and adrenal gland of adult male rats.

Results

Y chromosome fragments were amplified and sequenced using primers that included the entire Sry coding region and flanking sequences. The analysis of these sequences identified six Sry loci on the Y chromosome. These are paralogous copies consistent with a single phylogeny and the divergence between any two copies is less than 2%. All copies have a conserved reading frame and amino acid sequence consistent with function. Fragment analysis of genomic DNA showed close approximations of experimental with predicted values, validating the use of this method to identify proportions of each copy. Using the fragment analysis procedure with cDNA samples showed the Sry copies expressed were significantly different from the genomic distribution (testis p < 0.001, adrenal gland p < 0.001), and the testis and adrenal copy distribution in the transcripts were also significantly different from each other (p < 0.001). Total Sry transcript expression, analyzed by real-time PCR, showed significantly higher levels of Sry in testis than adrenal gland (p, 0.001).

Conclusion

The SHR Y chromosome contains at least 6 full length copies of the Sry gene. These copies have a conserved coding region and conserved amino acid sequence. The pattern of divergence is not consistent with gene conversion as the mechanism for this conservation. Expression studies show multiple copies expressed in the adult male testis and adrenal glands, with tissue specific differences in expression patterns. Both the DNA sequence analysis and RNA transcript expression analysis are consistent with more than one copy having function and selection preventing divergence although we have no functional evidence.

Seladin-1 expression in rat adrenal gland: effect of adrenocorticotropic hormone treatment

Seladin-1 (KIAA0018) gene is the seventh most highlyexpressed gene in the adult adrenal gland, along with genes coding for steroidogenic enzymes. The aim of the present study was to investigate the localization of the Seladin-1 protein in control and ACTH-treated rat adrenal glands and to verify whether Seladin-1 is involved in secretion. Immunofluorescence studies revealed that Seladin-1 was localized principally in the zona fasciculata, cytoplasm, and nucleus. Expression of Seladin-1 was increased by ACTH treatment, in vivo and in culture conditions. Subcellular fractionation offasciculata cells showed that Seladin-1 was mainly present in the nucleus, membrane, and cytoskeleton fractions and, to a lesser extent, in the cytosol. ACTH treatment decreased Seladin-1 expression in the cytosol, with a concomitant increase in the nuclear fraction. In the glomerulosa and fasciculata cells in culture, ACTH induced a relocalization of Seladin-1 into specific nuclear regions. This ACTH-induced relocalization was abrogated by the pre-treatment of cells with 75 nM U18666A (an inhibitor of Seladin-1). In addition, fasciculata cells exhibited an increase in the basal level of steroid secretion when cultured in the presence of U18666A (25 and 75 nM), although ACTH-induced secretion was decreased. In summary, the present study demonstrates that the protein expression of Seladin-1 is more abundant in fasciculata cells than in glomerulosa cells and that the ACTH treatment increases both expression and nuclear localization of the protein. Results also suggest that depending on its cellular localization, the Delta24-reductase activity of Seladin-1 may play a major role in steroid secretion in the adrenal gland.

Adrenal lipid profiles of chemically sympathectomized normoxic and hypoxic neonatal rats

Neonatal hypoxia is a common condition that elicits a coordinated endocrine response. In the neonatal rat, hypoxia induces an ACTH-independent increase in corticosterone which can be partially blocked by chemical sympathectomy. The present study sought to characterize the effects of sympathectomy on the adrenal lipid profile, since previous work suggested that augmented plasma corticosterone during hypoxia may be due to changes in adrenal lipid metabolism. Newborn rats were exposed to normoxia or hypoxia from birth to seven days of age, and guanethidine was used to produce the sympathectomy. Plasma epinephrine and norepinephrine were not significantly affected by hypoxia, while guanethidine decreased plasma norepinephrine in normoxic and hypoxic pups. Hypoxia alone increased the concentration of cholesterol esters in the adrenal gland; this increase was due to increases in cholesterol ester-associated oleic (18:1n9), docosahexaenoic (22:6n3), arachidonic (20:4n6), and adrenic (22:4n6) acids. Hypoxia also increased diglyceride-associated adrenic acid. Guanethidine treatment attenuated the hypoxia-induced increase in cholesterol ester-bound arachidonic and adrenic acids. Guanethidine also decreased saturated fatty acid concentrations and increased n3 fatty acid-enriched triglycerides. The results support the idea that the ACTH-independent corticosterone response to hypoxia in the neonatal rat is mediated by specific, sympathetically driven alterations in the adrenal lipid profile.

Jaw1/LRMP, a germinal centre-associated marker for the immunohistological study of B-cell lymphomas

Jaw1, also known as lymphoid-restricted membrane protein (LRMP), is an endoplasmic reticulum-associated protein. High levels of Jaw1/LRMP mRNA have been found in germinal centre B-cells and in diffuse large B-cell lymphomas of 'germinal centre' subtype. This paper documents Jaw1/LRMP expression at the protein level in human tissues by immunohistochemical and western blotting analysis using an antibody reactive with paraffin-embedded tissues. Jaw1/LRMP was highly expressed in germinal centre B-cells (in keeping with gene expression data), in 'monocytoid B-cells', and in splenic marginal zone B-cells. It was absent, or present at only low levels, in mature T-cells, although cortical thymocytes were weakly positive. Among lymphoid neoplasms, Jaw1/LRMP was found in germinal centre-derived lymphomas (follicle centre lymphoma, Burkitt's lymphoma, lymphocyte-predominant Hodgkin's disease) but not in T-cell neoplasms (with the exception of a single T lymphoblastic lymphoma). Classical Hodgkin's disease and myeloma lacked Jaw1/LRMP but many cases of chronic lymphocytic leukaemia (but not mantle zone lymphoma) were Jaw1/LRMP-positive. Approximately half of the marginal zone lymphomas were Jaw1/LRMP-positive. In diffuse large B-cell lymphomas, Jaw1/LRMP was found in three-quarters (24/32) of the cases classified phenotypically as being of 'germinal centre' type, but it was also expressed in almost half (13/28) of the 'non-germinal centre' cases. A similar proportion of 'non-germinal centre' cases were positive for the protein products of two other genes expressed highly in germinal centre cells (HGAL/GCET2 and PAG). The fact that all three of these proteins are expressed in a significant proportion of diffuse large B-cell lymphomas assigned to the 'non-germinal centre' category indicates that the immunophenotypic categorization of diffuse large B-cell lymphoma according to cellular origin may be more complicated than currently understood. Finally, the expression of Jaw1/LRMP in other types of lymphoma and in non-lymphoid tissues/tumours may be of interest in differential diagnosis and research.

Partial defects in transcriptional activity of two novel DAX-1 mutations in childhood-onset adrenal hypoplasia congenita

OBJECTIVE

Mutations in DAX-1, an X-linked gene encoding an orphan nuclear receptor, have been associated with adrenal hypoplasia congenita and hypogonadotropic hypogonadism. Here we describe two novel DAX-1 mutations, Y214X and I361T, associated with childhood-onset primary adrenal failure. We aimed at analysing their effects on protein localization, transcriptional activity and propose a structural-function relationship.

DESIGN

We have directly sequenced the DAX-1 gene from PCR-amplified DNA. The effect of the mutations on protein localization was assessed by immunocytochemistry in transfected cells. The impact of mutations on transcriptional activity was determined by transfection using a StAR promoter-luciferase reporter system.

RESULTS

The mutation Y214X produces a protein lacking the C-terminal half of DAX-1. The other one, I361T, affects a highly conserved amino acid within the putative ligand-binding domain. The mutant Y214X displayed a wild-type subcellular localization while I361T was partially retained in the cytoplasm. Both mutants retained subtantial transcriptional repressive activity, compared to mutants producing early onset adrenal failure. Interestingly, I361T displayed similar in vitro transcriptional repressive activity to the mutant I439S previously described in a case of late-onset AHC. This shows that molecular alterations of DAX-1 leading to similar in vitro activities may result in very different ages of onset of adrenal failure, which suggests that additional genetic and epigenetic factors are important in determining the clinical course of AHC.

CONCLUSIONS

Our results help the understanding of structure-function relationships in the DAX-1 molecule, suggesting that the N-terminal domain is relatively autonomous and add credence to presumed molecular interactions within ligand binding domain of the protein.

Stress hormones in mammals and birds: comparative aspects regarding metabolism, excretion, and noninvasive measurement in fecal samples

A multitude of endocrine mechanisms are involved in coping with challenges. Front-line hormones to overcome stressful situations are glucocorticoids (GCs) and catecholamines (CAs). These hormones are usually determined in plasma samples as parameters of adrenal activity and thus of disturbance. GCs (and CAs) are extensively metabolized and excreted afterwards. Therefore, the concentration of GCs (or their metabolites) can be measured in various body fluids or excreta. Above all, fecal samples offer the advantages of easy collection and a feedback-free sampling procedure. However, large differences exist among species regarding the route and time course of excretion, as well as the types of metabolites formed. Based on information gained from radiometabolism studies (reviewed in this paper), we recently developed and successfully validated different enzyme immunoassays that enable the noninvasive measurement of groups of cortisol or corticosterone metabolites in animal feces. The determination of these metabolites in fecal samples can be used as a powerful tool to monitor GC production in various species of domestic, wildlife, and laboratory animals.

Differential zonal expression and adrenocorticotropin regulation of secreted protein acidic and rich in cysteine (SPARC), a matricellular protein, in the midgestation human fetal adrenal gland: implications for adrenal development

CONTEXT

Matricellular proteins are a group of secreted, multifunctional extracellular matrix glycoproteins that includes thrombospondins (TSPs), tenascin-C, and secreted protein acidic and rich in cysteine (SPARC). They may be implicated in the dynamic developmental processes of the human fetal adrenal (HFA) in which the outer, definitive zone (DZ) cells are postulated to proliferate, migrate centripetally, differentiate, and populate the inner, steroidogenic fetal zone (FZ).

OBJECTIVE

The objective of the study was to identify a matricellular molecule that likely plays a major role in HFA development.

DESIGN

Studies involved RNA, cryosections, and cell cultures from 14- to 23-wk HFAs and human adult adrenal RNA.

MAIN OUTCOME MEASURES

Measures included transcripts encoding matricellular proteins, using real-time quantitative RT-PCR; SPARC localization by immunostaining; and ACTH regulation of SPARC expression and secretion by quantitative RT-PCR and Western blot.

RESULTS

SPARC HFA mRNA was 100-, 700-, and 300-fold higher than TSP-1, TSP-2, and tenascin-C mRNA, respectively. HFA SPARC mRNA was 3-fold higher than adult adrenals (P < 0.005), comparable with levels in adult brain (positive control), whereas mRNAs encoding TSP-1 and TSP-2 were lower in fetal than adult adrenals. SPARC immunoreactivity was detected exclusively in the FZ, not DZ. ACTH, a key regulator of HFA growth and function, increased SPARC mRNA (by 1.7-fold at 1 nm, 48 h, P < 0.05) in isolated FZ cells but not DZ cells. ACTH up-regulation of SPARC protein was also detected in FZ cell lysates and culture medium.

CONCLUSIONS

Results suggest a possible role for SPARC in development of functional and/or structural zonation of the HFA.

Cocaine- and amphetamine-regulated transcript peptide and sympatho-adrenal axis

Cocaine- and amphetamine-regulated transcript peptide (CART) is constitutively expressed in discrete regions of the mammalian central and peripheral nervous system. Immunohistochemical studies reveal a well-defined network of CART-immunoreactive (irCART) neurons organized along the sympatho-adrenal axis. Sympathetic preganglionic neurons, but not parasympathetic preganglionic neurons, in the lateral horn area are CART-positive; which in turn innervate postganglionic neurons in the paravertebral and prevertebral sympathetic ganglia as well as the adrenal medulla. A population of chromaffin cells in the adrenal medulla is CART-positive; whereas, postganglionic neurons are not. Sympathetic preganglionic neurons themselves are contacted by irCART cell processes arising from neurons in the arcuate nucleus, the retrochiasmatic nucleus and the rostral ventrolateral medulla. Results from several recent studies suggest CART directly excites neurons along the sympathetic neural axis or indirectly by potentiating the action of glutamate on NMDA receptors, as evidenced by an elevation of blood pressure and heart rate following intracerebroventricular, intracisternal or intrathecal administration of the peptide to anesthetized rats or conscious rabbits.

Cellular and subcellular localization of paralemmin-1, a protein involved in cell shape control, in the rat brain, adrenal gland and kidney

Paralemmin-1 is a phosphoprotein, lipid-anchored to the cytoplasmic face of membranes and implicated in plasma membrane dynamics and cell process formation. We report an immunoperoxidase histochemical analysis of the cellular and subcellular localization of paralemmin-1 in the rat tissues where its expression is highest: the brain, the adrenal gland and the kidney. Paralemmin-1 is detected throughout the brain, in neuronal perikarya, axons and dendrites including dendritic spines and also in glial processes. In the adrenal gland, paralemmin-1 is highly expressed in the medulla. The kidney displays a pattern of differential paralemmin-1 expression in various structures and cell types, with high concentrations in cells of the parietal epithelium of Bowman's capsule, intermediate tubules, distal tubules and principal cells of outer medullary collecting ducts. Mosaics of paralemmin-positive and paralemmin-negative cells are observed in proximal tubules, the parietal epithelium of Bowman's capsule and the endothelium of many blood vessels. Plasma membrane association in epithelia is often polarized: paralemmin-1 concentrates at the apical membranes of adrenal chromaffin cells, but at the basolateral plasma membranes of proximal and distal tubule cells in the kidney. Paralemmin-1 immunoreactivity exhibits a spotted pattern and can be seen both at plasma membranes and within the cytoplasm, where it is often associated with endomembranes. This discontinuous distribution and the detergent extraction properties of paralemmin-1 suggest an association with lipid microdomains. The findings are consistent with a role for paralemmin-1 in the formation and stabilization of plasma membrane elaborations, in neurons as well as in other cell types.

Cellular expression of Noc2, a Rab effector protein, in endocrine and exocrine tissues in the mouse

Noc2 is a Rab effector which participates in regulated exocytosis. It is expressed abundantly in endocrine cells but at low levels in exocrine tissues. Noc2-deficient mice, however, exhibit marked accumulation of secretory granules in exocrine cells rather than endocrine cells. In the present study, we investigated localization of Noc2 immunohistochemically in various endocrine and exocrine tissues in normal mice. Western blotting detected a Noc2-immunoreactive band of 38 kDa in isolated pancreatic islets, the adrenal gland, pituitary gland, and thyroid gland. Immunostaining for Noc2 labeled endocrine cells in the adrenal medulla and adenohypophysis, pancreatic islet cells, thyroid parafollicular cells, and gut endocrine cells, supporting the notion that Noc2 is a Rab effector protein shared by amine/peptide-secreting endocrine cells. Besides endocrine tissues, granular ducts in salivary glands contained Noc2. Although immunostaining failed to detect Noc2 in acinar cells of all exocrine glands examined, reverse transcriptase-polymerase chain reaction analysis detected the mRNA expression in exocrine pancreas. Ultrastructurally, Noc2 immunoreactivity was associated with the limiting membrane of granules in both pancreatic endocrine and salivary duct exocrine cells. The cellular and subcellular localizations of Noc2 should yield key information on its functional significance as well as account for the phenotype in Noc2-deficient mice.

Characterization of natural vasostatin-containing peptides in rat heart

Chromogranin A (CGA) is a protein that is stored and released together with neurotransmitters and hormones in the nervous, endocrine and diffuse neuroendocrine systems. As human vasostatins I and II [CGA(1-76) and CGA(1-113), respectively] have been reported to affect vessel motility and exert concentration-dependent cardiosuppressive effects on isolated whole heart preparations of eel, frog and rat (i.e. negative inotropism and antiadrenergic activity), we investigated the presence of vasostatin-containing peptides in rat heart. Rat heart extracts were purified by RP-HPLC, and the resulting fractions analyzed for the presence of CGA N-terminal fragments using dot-blot analysis. CGA-immunoreactive fractions were submitted to western blot and MS analysis using the TOF/TOF technique. Four endogenous N-terminal CGA-derived peptides [CGA(4-113), CGA(1-124), CGA(1-135) and CGA(1-199)] containing the vasostatin sequence were characterized. The following post-translational modifications of these fragments were identified: phosphorylation at Ser96, O-glycosylation (trisaccharide, NAcGal-Gal-NeuAc) at Thr126, and oxidation at three methionine residues. This first identification of CGA-derived peptides containing the vasostatin motif in rat heart supports their role in cardiac physiology by an autocrine/paracrine mechanism.

Metabolic alterations in rat myocardium in experimental acute atrial fibrillation

Experimental atrial fibrillation in intact rats significantly decreased the content of catecholamines in atrial adrenergic fibers and phosphorylase activity, which attests to enhanced glycogen consumption in the heart. These changes were specific of the fibrillating myocardium and atria, but were absent in the ventricles. Induced atrial fibrillation did not modify activities of SDH and monoamine oxidase in cardiac subdivisions. It was hypothesized that increased energy requirements in the atria during myocardial fibrillation led to activation of anaerobic metabolism.

Antecedent hypoglycemia, catecholamine depletion, and subsequent sympathetic neural responses

Antecedent hypoglycemia is well known to impair sympathetic responses to subsequent hypoglycemia. However, it is less clear whether this occurs through altered sympathetic neural traffic or through decreased adrenal catecholamine release per se. It is also not clear whether antecedent hypoglycemia impairs sympathetic responsiveness to subsequent nonhypoglycemic sympathetic stimuli. We exposed rats to two episodes of insulin-induced hypoglycemia or sham hypoglycemia (n = 15 per group) on d -2 and -1 before exposure to transient (10 min) hypotension on d 0. Adrenal sympathetic nerve activity (SNA) was directly recorded in the conscious state and plasma catecholamine concentrations were assessed. We also examined the effect of antecedent hypoglycemia on phosphorylated and nonphosphorylated tyrosine hydroxylase (TH) protein expression as well as the expression of phenylethanolamine N-methyltransferase. Adrenal SNA was not significantly altered by antecedent hypoglycemia either at baseline of d 0 (before hypotension) or in response to hypotension. In contrast, plasma epinephrine (EPI) responsiveness was impaired by more than 50% (P = 0.025) in rats exposed to antecedent vs. sham hypoglycemia. Antecedent hypoglycemia had no effect on norepinephrine responsiveness to hypotension. In studies of adrenal tissue from separate rats, antecedent hypoglycemia decreased adrenal EPI content but did not significantly alter the expression of TH, phosphorylated TH, or phenylethanolamine N-methyltransferase. In summary, antecedent hypoglycemia impaired EPI responsiveness to subsequent hypotension despite no reduction in adrenal SNA and in association with reduced adrenal EPI content. Thus, antecedent hypoglycemia impaired responsiveness to a subsequent nonhypoglycemic sympathetic stimulus, an effect mediated at the level of the adrenal medullae.