The possible involvement of LH/hCG induced mitochondrial proteins in the regulation of steroidogenesis in bovine luteal cells

Beta-2-microglobulin (B2M) forms the small invariable light chain subunit of class I HLA antigens on the cell membrane of all nucleated cells. During the continuous turnover of the HLA molecules, B2M is shed from the cell membrane into blood. Lymphocytes are the main source of serum free B2M. Serum B2M concentration is increased in renal diseases, various malignant diseases and some inflammatory and autoimmune disorders. In lymphatic malignancies serum B2M has significant prognostic value. Interferons (IFNs) have the ability to enhance the expression of class I and II histocompatibility antigens. Accordingly, IFNs cause a rise in formation and release of B2M. Currently, treatment with IFN alpha is used in diseases, like multiple myeloma, where serum B2M measurements are used to assess tumor burden. We have measured serum B2M levels during IFN alpha treatment in patients with both multiple myeloma and chronic myeloproliferative diseases, and IFN alpha caused a significant increase in serum B2M. It can be concluded that use of IFN alpha abolishes the value of serum B2M as an indicator of disease activity.     

The involvement of nitric oxide in stress-impaired testicular steroidogenesis

The participation of the nitric oxide (NO) pathway in downregulation of testicular steroidogenesis in normal and stressed rats was investigated both in vivo and in vitro. In Leydig cells from normal animals, isosorbide dinitrate, an NO donor, decreased the human chorionic gonadotropin (CG)-stimulated and progesterone-derived androgen production. Also, the intratesticular injection of a precursor of NO, arginine (10 mg/testis), transiently decreased serum androgen levels and inhibited human CG-stimulated androgen production in acute testicular cultures. These effects were eliminated in rats cotreated with Nomega-nitro-L-arginine methyl ester (L-NAME) (2 X 600 microg/each testis). Acute immobilization stress (2 h) decreased serum androgen levels and inhibited human CG-stimulated androgen production in vitro. These effects were accompanied by a significant increase in nitrite, a stable oxidation product of NO, in testicular cultures. Bilateral intratesticular injection of L-NAME prevented the stress-induced decrease of human CG-stimulated androgen production, and significantly reduced the nitrite levels. These results implicate NO in normal and stress-impaired testicular steroidogenesis.     

The possible involvement of pancreatic polypeptide in the paracrine regulation of human and rat adrenal cortex

Pancreatic polypeptide (PP) is a member of a family of 36-amino acid brain-gut peptides, including neuropeptide Y (NPY) and polypeptide YY (PYY) and acting through many subtypes of Y receptors belonging to the superfamily of the G protein-coupled receptors. PP was found to increase both glucocorticoid and cyclic-AMP production by dispersed rat and human adrenocortical cells in a concentration-dependent manner. Minimal and maximal effective concentrations were 10(-10) and 10(-8) M, respectively. The glucocorticoid secretagogue effect of 10(-8) M PP was blocked by the protein kinase A (PKA) unhibitor H-89, but not by the ACTH-receptor antagonist corticotropin-inhibiting peptide (CIP) Autoradiography showed the presence of [125I]PP binding sites in the inner zones of rat and human adrenal cortex, which were not displaced by NPY, PYY, ACTH or CIP. Sizable amounts of PP-immunoreactivity were detected in the medulla of both rat and human adrenals (about 50-100 fmol/mg); this content may give rise, upon submaximal stimulation of PP release, to local intraadrenal concentrations of about 10(-8)/10(-7) M. Collectively, these findings allow us to draw the following conclusions: (i) PP stimulates glucocorticoid secretion, acting through specific receptors coupled with the adenylate cyclase/PKA-dependent signaling pathway; and (ii) PP could be included in that group of regulatory peptides, contained in adrenal medulla, which are able to control the secretory function of the cortex acting in a paracrine manner.     

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.     

Comparative characteristics of steroidogenesis and its biorhythm in the hyperfunctioning adrenal cortex

The paper summarizes the results od several studies of the daily rhythms of steroid hormones in patients with ACTH-dependent Itsenko-Cushing's disease (CD) and congenital adrenal hyperplasia (late-onset forms) (CAH). Normal daily rhythms of adrenal C21- and C19-steroids and ACTH were observed in 23.5% of CD patients. CAH patients had the marked daily rhythms of adrenal androgens and testosterone which were typical of those of cortisole. The ratios of steroid hormones to its precursors provide evidence for enhanced activities of 17-, 11 beta- and 18-hydroxylases in CD patients and normal enzymatic activities in CAH patients, whereas 21-hydroxylase being an exception.     

Transneuronal labeling of CNS neurons involved in the innervation of the adrenal gland

In the light of the observation obtained with the application of the viral-tract tracing method, the CNS connection of the adrenal gland, with focusing on the central nervous connection of the adrenal cortex is reviewed.     

Effects of long-term growth hormone therapy on adrenal steroidogenesis in Turner syndrome

Nature's most potent molecules are produced by enzyme-catalysed reactions, coupled with the natural selection of those products that possess optimal biological activity. Combinatorial biocatalysis harnesses the natural diversity of enzymatic reactions for the iterative synthesis of organic libraries. Iterative reactions can be performed using isolated enzymes or whole cells, in natural and unnatural environments, and on substrates in solution or on a solid phase. Combinatorial biocatalysis is a powerful addition to the expanding array of combinatorial methods for the generation and optimization of lead compounds in drug discovery and development.     

Neurohistochemical evaluation of adrenergic innervation in fetal development of the white rat

Physiological development of adrenergic innervation, an important component of trophic and homeostatic regulation in the mammals was estimated. Our research is directed to evaluate both exo- and endogenous factors contributing to its impairment. The present investigation was carried out on 32 rat fetuses from three various 7-day periods of gestation. Histochemical studies included reactions to catecholamines according to Falck and Owman, and silver staining with AgNO3 according to the Bielschowsky-Gros method. Adrenergic innervation was examined in all fetal body regions, with a special reference to the pelvis. Catecholamines distribution and accumulation in plexuses, ganglia, neurons and chromatophilic cells, as well as serotonine content in mast cells were analyzed. It was found that in the initial period of gestation noradrenaline is absent. In the third week of gestation, the neurotransmitter's accumulation takes place to subsequently decrease gradually until the end of gestation. From this stage synaptic connections of adrenergic innervation with chromatophilic and mast cells could be detected.     

Developmental expression of the peripheral-type benzodiazepine receptor and the advent of steroidogenesis in rat adrenal glands

Although the precise mechanism whereby cholesterol is transported across the outer mitochondrial membrane is uncertain, a multimeric receptor complex termed the peripheral-type benzodiazepine receptor (PBR) appears essential for this process. We therefore predicted that adrenal cells at different developmental stages would express PBR coincidentally with the advent of steroidogenesis. Adrenals of neonatal rats demonstrate greatly reduced sensitivity to ACTH that gradually increases after the first 2 weeks of life. Thus, neonates have lower circulating corticosterone levels following exposure to stress. We examined mitochondrial PBR ligand binding activity, immunoreactive (ir) PBR content, and adrenal sensitivity to ACTH in vivo and in vitro. Ontogeny of both mitochondrial PBR ligand binding capacity and irPBR directly paralleled that of ACTH-inducible steroidogenesis in isolated rat adrenal cells and in rats injected with ACTH. In addition, neonatal PBR had approximately 2-fold higher affinity for PK11195, a synthetic ligand that binds with high affinity to PBR. No correlation was observed during neonatal life between ir-steroidogenic acute regulatory (StAR) protein content and steroidogenesis. These results are consistent with the hypothesis that PBR is an absolute prerequisite for adrenocortical steroidogenesis, and suggest that the stress hyporesponsive period of neonatal rats may result from decreased PBR expression. In addition, the higher affinity of neonatal PBR and the relatively high basal expression of StAR protein in neonatal adrenals may partly explain the high constitutive steroidogenesis characteristic of neonatal rat adrenal cells.     

Ontogeny of innervation of rat and ovine fetal adrenals

The formation of adrenocortical zonation occurs in rats during late gestation. Since adult cortical function is modulated by neural mediators, it is possible that the development of differentiated function is dependent on cortical innervation. The goal of this study was to compare the pattern and timing of rodent and ovine adrenal innervation during late organogenesis by staining with antibodies directed against the neuropeptides vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP) and neuropeptide tyrosine (NPY) and the catecholamine biosynthetic enzyme, tyrosine hydroxylase (TOH). Rat adrenals were collected from fetal days 17-21 (term=21 days) and ovine adrenals from fetal days 101-136 (term=145 days). Adrenals were fixed, cryosectioned at 100 microns and immunostained using Cy3-conjugated secondary antibodies. In both species, staining of VIP, CGRP, NPY and TOH fibers was observed in the capsule and subcapsular layers of the cortex during gestation. In late gestation, VIP- and NPY-positive ganglions cells were observed near the medulla extending processes toward the outer cortex; in ovine adrenals, fibers from ganglion cells appeared to surround nests of outer cortical (presumably, zona glomerulosa) cells. These data show that phenotypically distinct neural elements appear at different stages of adrenocortical development. The presence of neural elements in contact with adrenal cortical cells supports the possibility for neural control of adrenocortical development.     

Possible involvement of proteases in the regulation of spermatogenesis

Proteolytic enzymes, which are synthesized and secreted by cells of the seminiferous tubule of the testis, have important functions in spermatogenesis. We performed metabolic studies using small peptide hormones as a substrate to investigate the activity of proteases in cultured Sertoli cells of the rat. High-performance liquid chromatographic analysis of the cell culture supernatants showed cleavage of met- and leu-enkephalin, substance P, and bradykinin. No peptidolysis was observed for the cyclic peptide oxytocin. The hormone cleavage pattern and the use of specific protease inhibitors in peptide degradation experiments demonstrated activities of several proteases in Sertoli cells. These are mainly metalloproteinases including neutral metalloendopeptidases, angiotensin-converting enzyme and aminopeptidases. In addition, activities of serine and aspartic proteases were detected. Only marginal proteolytic activities were observed in Sertoli cell conditioned supernatants, indicating that the investigated proteases are mainly located on Sertoli cell membranes. The peptide hormones used in this study have been found to play a potential role in the endocrine, paracrine or autocrine regulation of testicular cells. The membrane-associated proteases reported here may therefore be involved in the metabolism and inactivation of these peptides.     

Cytosolic and mitochondrial proteins as possible targets of cycloheximide effect on adrenal steroidogenesis

We investigated the in vitro and in vivo interaction between amiodarone and lidocaine. The interaction on a molecular level was first studied in microsomes from 11 human livers. Close correlations between amiodarone N-monodesethylase activities and (a) the amounts of cytochrome P-4503A4 (CYP3A4), and (b) the rates of lidocaine N-monodesethylation were observed. Lidocaine inhibited amiodarone N-monodesethylation (Ki = 120 microM) competitively; inversely, amiodarone suppressed lidocaine N-monodesethylase activity in the same manner (Ki = 47 microM). Moreover, the metabolite N-monodesethylamiodarone (DEA) was stable and inhibited lidocaine metabolism in a concentration-dependent manner. The in vivo interaction was investigated in 6 cardiac patients. Each of them received a dose of 1 mg/kg lidocaine hydrochloride intravenously (i.v.) on three different occasions: before amiodarone treatment (control), and after cumulative doses of 3 g (phase I) and 13 g (phase II), respectively, amiodarone hydrochloride. The analysis of lidocaine pharmacokinetics showed an increase in lidocaine area under the curve (AUC) when amiodarone was administered, whereas that of N-monodesethylated lidocaine decreased. Moreover, the systemic clearance of lidocaine decreased, while the elimination half-life (t1/2) and the distribution volume at steady state of lidocaine remained unchanged. The pharmacokinetic parameters during phase II were the same as those during phase 1, indicating that the interaction had already occurred early in the loading phase of amiodarone administration. The interaction between amiodarone and lidocaine may be explained by the inhibition of CYP3A4 by amiodarone and/or by its main metabolite DEA.     

The role of nitric oxide in the regulation of aldosterone synthesis by adrenal glomerulosa cells

The role of nitric oxide (NO) in the regulation of aldosterone synthesis in the adrenal glomerulosa is not known. In this study, we observed that liberators of NO such as S-nitroso-N-acetyl-penicillamine (SNAP), sodium nitroprusside (Snp) and spermine nonoate (SNO) could significantly inhibit angiotensin II (AII) and ACTH-induced aldosterone synthesis in isolated rat and cultured human adrenal glomerulosa cells. To evaluate more precisely whether glomerulosa cells express NO synthase, we performed immunoblotting experiments with antibodies specific for the endothelial type ecNO synthase as well as the neuronal NO synthase. This revealed the presence of the ecNO synthase in rat adrenal capsules, in normal and in adenomatous human adrenal glomerulosa tissue, as well as in freshly dispersed rat adrenal glomerulosa cells. Furthermore, on immunohistochemical analysis, rat adrenal glomerulosa cell sections showed strongly positive staining for ecNO synthase. These results suggest that NO may be an important negative modulator of adrenal glomerulosa steroidogenesis.     

The expression and regulation of chick EphA7 suggests roles in limb patterning and innervation

Eph receptors and their ligands, the ephrins, have been implicated in early patterning and axon guidance in vertebrate embryos. Members of these families play pivotal roles in the formation of topographic maps in the central nervous system, the formation of brain commissures, and in the guidance of neural crest cells and motor axons through the anterior half of the somites. Here, we report a highly dynamic expression pattern of the chick EphA7 gene in the developing limb. Expression is detected in discrete domains of the dorsal mesenchyme from 3 days of incubation. The expressing cells are adjacent to the routes where axons grow to innervate the limb at several key points: the region of plexus formation, the bifurcation between dorsal and ventral fascicles, and the pathway followed by axons innervating the dorsal muscle mass. These results suggested a role for EphA7 in cell-cell contact-mediated signalling in dorsal limb patterning and/or axon guidance. We carried out experimental manipulations in the chick embryo wing bud to alter the dorsoventral patterning of the limb. The analyses of EphA7 expression and innervation in the operated wings indicate that a signal emanating from the dorsal ectoderm regulates EphA7 in such a way that, in its absence, the wing bud lacks EphA7 expression and shows innervation defects at the regions where the gene was downregulated. EphA7 downregulation in the dorsal mesenchyme after dorsal ectoderm removal is more rapid than that of Lmx-1, the gene known to mediate dorsalisation in response to the ectodermal signal. These results add a new gene to the dorsalisation signalling pathway in the limb. Moreover, they implicate the Eph receptor family in the patterning and innervation of the developing limb, extending its role in axon pathfinding to the distal periphery.     

The involvement of specific immune reactions in the regulation of acid-forming function of the stomach in duodenal ulcers

Fifty patients with duodenal ulcer disease were examined. In 17 patients (1 group) the constantly recurrent course of the disease was noted, in 33 patients (2 group) the complications (hemorrhage, perforation, stenosing) have occurred in anamnesis. In patients of the first group the acid production rising was concomitant with specific somatostatin-dependent cell reactions domination, in the second one--pentagastrin-dependent.     

Effects of long-term pravastatin treatment on spermatogenesis and on adrenal and testicular steroidogenesis in male hypercholesterolemic patients

STUDY OBJECTIVE: To determine if there are significant differences in birth outcomes and survival for infants delivered by certified nurse midwives compared with those delivered by physicians, and whether these differences, if they exist, remain after controlling for sociodemographic and medical risk factors. DESIGN: Logistic regression models were used to examine differences between certified nurse midwife and physician delivered births in infant, neonatal, and postneonatal mortality, and risk of low birthweight after controlling for a variety of social and medical risk factors. Ordinary least squares regression models were used to examine differences in mean birthweight after controlling for the same risk factors. STUDY SETTING: United States. PATIENTS: The study included all singleton, vaginal births at 35-43 weeks gestation delivered either by physicians or certified nurse midwives in the United States in 1991. MAIN RESULTS: After controlling for social and medical risk factors, the risk of experiencing an infant death was 19% lower for certified nurse midwife attended than for physician attended births, the risk of neonatal mortality was 33% lower, and the risk of delivering a low birthweight infant 31% lower. Mean birthweight was 37 grams heavier for the certified nurse midwife attended than for physician attended births. CONCLUSIONS: National data support the findings of previous local studies that certified nurse midwives have excellent birth outcomes. These findings are discussed in light of differences between certified nurse midwives and physicians in prenatal care and labour and delivery care practices. Certified nurse midwives provide a safe and viable alternative to maternity care in the United States, particularly for low to moderate risk women.     

Serotonergic innervation of the hypothalamic suprachiasmatic nucleus and photic regulation of circadian rhythms

Converging lines of evidence have firmly established that the hypothalamic suprachiasmatic nucleus (SCN) is a light-entrainable circadian oscillator in mammals, critically important for the expression of behavioral and physiological circadian rhythms. Photic information essential for the daily phase resetting of the SCN circadian clock is conveyed directly to the SCN from retinal ganglion cells via the retinohypothalamic tract. The SCN also receives a dense serotonergic innervation arising from the mesencephalic raphe. The terminal fields of retinal and serotonergic afferents within the SCN are co-extensive, and serotonergic agonists can modify the response of the SCN circadian oscillator to light. However, the functional organization and subcellular localization of 5HT receptor subtypes in the SCN are just beginning to be clarified. This information is necessary to understand the role 5HT afferents play in modulating photic input to the SCN. In this paper, we review evidence suggesting that the serotonergic modulation of retinohypothalamic neurotransmission may be achieved via at least two different cellular mechanisms: 1) a postsynaptic mechanism mediated via 5HT1A or 5ht7 receptors located on SCN neurons; and 2) a presynaptic mechanism mediated via 5HT1B receptors located on retinal axon terminals in the SCN. Activation of either of these 5HT receptor mechanisms in the SCN by specific 5HT agonists inhibits the effects of light on circadian function. We hypothesize that 5HT modulation of photic input to the SCN may serve to set the gain of the SCN circadian system to light.