bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of inhibin-related peptides and oestradiol on androstenedione and progesterone secretion by bovine theca cells in vitro
Authors: Wrathall J H M , Knight P G
Published: December 2008

Primary monolayer cultures of bovine theca cells isolated from pooled ovarian follicles (3–10 mm diameter) were used to examine the effects of various granulosa cell-derived substances on basal and luteinizing hormone (LH)-induced androgen and progesterone secretion. After an overnight pretreatment period, cells were incubated with a range of treatments including LH, oestradiol-17β, inhibin, activin and follistatin. Media were collected after 48 h and assessment of androstenedione and progesterone secretion made by radioimmunoassay.

Addition of LH (5–50 ng/ml) to the cells resulted in a dose-dependent stimulation of both androstenedione (2·5-to 3-fold rise; P<0·01) and progesterone (∼ 1·6-fold rise; P<0·001) production. Secretion of androstenedione was also raised (up to 5-fold; P<0·001) by addition of oestradiol-17β (0·3–300 ng/ml), whilst levels of the androgen in the presence of both LH (20 ng/ml) and oestradiol (300 ng/ml) were up to 12-fold higher (P<0·001) than control values. In contrast, oestradiol treatment inhibited by up to 50% both basal (P<0·001) and LH-stimulated (P<0·001) secretion of progesterone. Exposure of cells to purified bovine inhibin (5–125 ng/ml) consistently raised androstenedione secretion by up to 42% over basal levels (P<0·001). Inhibin also enhanced both LH-stimulated (∼20%; P<0·001) and oestradiol-stimulated (∼20%; P<0·05) secretion of androstenedione. In direct contrast, treatment of theca cells with human recombinant activin-A (1–50 ng/ml) inhibited both LH-stimulated (∼50%; P<0·001) and oestradiol-stimulated (∼30%; P<0·005) androstenedione secretion. Activin also reversed the positive effect of inhibin on basal (P<0·01), LH-stimulated (P<0·001) and oestradiol-stimulated (P<0·001) androstenedione secretion, though activin alone did not affect basal steroid output. Simultaneous addition of human recombinant follistatin reversed the inhibitory effects of activin on LH- and oestradiol-induced androstenedione secretion but did not modify the effects of inhibin. Follistatin alone did not alter either basal or LH-stimulated androstenedione output. Neither basal nor LH-stimulated secretion of progesterone were consistently affected by inhibin, activin or follistatin.

As well as confirming the stimulatory effects of both LH and oestradiol on bovine thecal cell androgen production, these observations are indicative of opposing intrafollicular paracrine roles for granulosa cell-derived inhibin and activin in modulating thecal cell responses to gonadotrophins and steroids in the bovine ovary. Though inhibin and oestradiol had qualitatively similar effects in promoting thecal androgen secretion, the magnitude of the response to oestradiol was much greater. The results also support an intrafollicular role of follistatin as a binding protein capable of neutralizing the effect of activin, but not inhibin, on thecal androgen production.

Journal of Endocrinology (1995) 145, 491–500
Divergent effects of gonadotrophin-releasing hormone (GnRH) analogue and authentic GnRH on the anterior pituitary gland of rats with restricted feeding
Authors: Goto K , Kotsuji F , Tominaga T
Published: December 2008

The effects of gonadotrophin-releasing hormone analogue (GnRHa; buserelin) on the pituitary function and morphology of food-restricted rats were compared with those of authentic GnRH. After adult female rats had been restricted to 10 g food/day for 60 days, various doses of GnRHa (10 ng, 100 ng and 1 μg) or GnRH (10 μg) were administered either daily for 7 days or twice a week for 4 weeks from day 61 of the period of underfeeding. Underfeeding brought about a decrease in the pituitary gonadotrophin content, serum levels of gonadotrophins and oestradiol, and the number and size of both LH- and FSH-positive pituitary cells. Daily and/or twice-weekly administration of authentic GnRH to underfed rats produced an increase in pituitary and serum gonadotrophin levels and the number and size of both LH- and FSH-positive pituitary cells. The administration of GnRHa daily for 7 days increased serum gonadotrophin levels, while it produced a reduction in the pituitary gonadotrophin content and number and size of both LH- and FSH-positive pituitary cells in a dose-dependent manner. Twice-weekly administration of GnRHa also produced an elevation of serum gonadotrophin levels and reduction of pituitary gonadotrophin content, although it did not affect the numbers and areas of LH- and FSH-positive pituitary cells. A GnRH loading test performed after the GnRHa treatment showed that the GnRHa treatment performed in this study did not produce down-regulation of the GnRH receptor. Thus, it can be concluded that the gonadotrophin-synthesizing activity of GnRHa is weaker than that of authentic GnRH, or that GnRHa may preferentially exert gonadotrophin-releasing activity rather than gonadotrophin-synthesizing activity in the anterior pituitary of underfed rats.

Journal of Endocrinology (1995) 145, 501–511
Nitric oxide synthase in the rat fallopian tube is regulated during the oestrous cycle
Authors: Bryant C E , Tomlinson A , Mitchell J A , Thiemermann C , Willoughby D A
Published: December 2008

Nitric oxide produced from l-arginine by nitric oxide synthase (NOS) acts in a variety of biological processes via the stimulation of guanylyl cyclase and subsequent elevation of cGMP. Constitutive, calcium-dependent isoforms of NOS are found in endothelial cells (eNOS) and neurones (nNOS), while macrophages express an inducible, calcium-independent isoform (iNOS) in response to the action of certain cytokines or bacterial endotoxin. While the regulation of NOS by exogenous glucocorticoids and steroid hormones is well documented, the effects of endogenous steroid hormones on NOS activity, such as those released during the oestrous cycle, is unknown. Here we demonstrate, using specific antibodies for eNOS, nNOS and iNOS, the presence of NOS in the epithelium of rat fallopian tubes at pro-oestrus, late pro-oestrus, oestrus, metoestrus and dioestrus. Western blot analysis of rat fallopian tube homogenates revealed a protein band at approximately 125 kDa which was recognised by antibodies to different isoforms of NOS, but no bands at the expected molecular weights (eNOS, 140 kDa; nNOS, 160 kDa; iNOS, 135 kDa). NOS activity in fallopian tubes was measured by the conversion of l-[3H]arginine to l-[3H]citrulline. Both calcium-dependent and -independent NOS activities were present. However, in late pro-oestrus when circulating oestrogens are low, NOS activity was reduced in comparison to all other stages of the oestrous cycle. Thus we show that NOS is present in the epithelial lining of the fallopian tube and is recognised at a previously undescribed molecular weight. The changes in NOS activity in these cells during the oestrous cycle may modulate tube motility and contribute to sucessful fertility.

Journal of Endocrinology (1995) 146, 149–157
Glucagon-like peptide-1 binding to rat hepatic membranes
Authors: Villanueva-Peñacarrillo M L , Delgado E , Trapote M A , Alcántara A , Clemente F , Luque M A , Perea A , Valverde I
Published: December 2008

We have found [125I]glucagon-like peptide (GLP)-1(7–36)amide specific binding activity in rat liver and isolated hepatocyte plasma membranes, with an Mr of approximately 63 000, estimated by cross-linking and SDS-PAGE. The specific binding was time- and membrane protein concentration-dependent, and equally displaced by unlabelled GLP-1(7–36)amide and by GLP-1(1–36)amide, achieving its ID50 at 3×10−9 m of the peptides. GLP-1(7–36)amide did not modify the basal or the glucagon (10−8 m)-stimulated adenylate cyclase in the hepatocyte plasma membranes. These data, together with our previous findings of a potent glycogenic effect of GLP-1(7–36)amide in isolated rat hepatocytes, led us to postulate that the insulin-like effects of this peptide on glucose liver metabolism could be mediated by a type of receptor probably different from that described for GLP-1 in pancreatic B-cells or, alternatively, by the same receptor which, in this tissue as well as in muscle, uses a different transduction system.

Journal of Endocrinology (1995) 146, 183–189
Further studies on the regulation, localization and function of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in the rat anterior pituitary gland
Authors: Rondeel J M M , Klootwijk W , Linkels E , Jeucken, W P H M , Hofland L J , Everts M E , Kramer P , de Jong F H , van Haasteren G A C , Cockle S M , Visser T J , de Greef W J
Published: December 2008

Recent evidence shows that thyrotrophin-releasing hormone (TRH) immunoreactivity in the rat anterior pituitary gland is accounted for by the TRH-like tripeptide prolineamide-glutamyl-prolineamide (pGlu-Glu-ProNH2, <EEP-NH2). The present study was undertaken to investigate further the regulation, localization and possible intrapituitary function of <EEP-NH2. Anterior pituitary levels of <EEP-NH2 were determined between days 5 and 35 of life, during the oestrous cycle and after treatment with the luteinizing hormone-releasing hormone (LHRH) antagonist Org 30276. Treatment of adult males with the LHRH antagonist either for 1 day (500 μg/100 g body weight) or for 5 days (50 μg/100 g body weight) reduced anterior pituitary <EEP-NH2 levels by 25–30% (P<0·05 versus saline-treated controls). Anterior pituitary <EEP-NH2 increased between days 5 and 35 of life. In females, these levels were 2- to 3-fold higher (P<0·05) than in males between days 15 and 25 after birth; these changes corresponded with the higher plasma follicle-stimulating hormone (FSH) levels in the female rats. After day 25, <EEP-NH2 levels in female rats decreased in parallel with a decrease in plasma FSH. Injections with the LHRH antagonist (500 μg/100 g body weight), starting on day 22 of life, led to reduced contents of <EEP-NH2 in the anterior pituitary gland of female rats on days 26 and 30 (55 and 35% decrease respectively). Levels of <EEP-NH2 in the anterior pituitary gland did not change significantly during the oestrous cycle. Fractionation of anterior pituitary cells by unit gravity sedimentation was found to be compatible with the localization of <EEP-NH2 in gonadotrophs. In vitro, <EEP-NH2 dose-dependently inhibited TRH-stimulated growth hormone (GH) release from anterior pituitary cells obtained from neonatal rats, but no consistent effects were seen on the in vitro release of luteinizing hormone (LH), FSH, prolactin (PRL) or thyroid-stimulating hormone (TSH) under basal or TRH/LHRH-stimulated conditions. Furthermore, <EEP-NH2 did not affect the in vitro hormone release by anterior pituitary cells obtained from adult rats. In vivo, <EEP-NH2 (0·3–1·0 μg intravenously) did not affect plasma PRL, TSH, LH, FSH and GH in adult male rats. We conclude that <EEP-NH2 in the anterior pituitary gland is regulated by LHRH, is probably localized in gonadotrophs and may play a (paracrine) role in neonatal GH release.

Journal of Endocrinology (1995) 146, 293–300
Evidence for a direct action of GH on haemopoietic cells of a marine fish, the gilthead sea bream (Sparus aurata)
Authors: Calduch-Giner J A , Sitjà-Bobadilla A , Álvarez-Pellitero P , Pérez-Sánchez J
Published: December 2008

Receptors for GH were characterized in the head kidney of gilthead sea bream (Sparus aurata), using radioiodinated and biotinylated ligands. The specific binding of radiolabelled recombinant gilthead sea bream GH (rsbGH) to head kidney membrane preparations was dependent on membrane concentration. Salmon prolactin, salmon gonadotrophin and carp gonadotrophin did not compete for 125I-labelled rsbGH-binding sites. Unlabelled rsbGH competitively displaced 125I-labelled rsbGH bound to head kidney membranes. Scatchard plots were always linear, denoting the presence of a single class of binding sites. The binding affinity (Ka=2·7 × 109 m−1) was equivalent to that found in liver membrane preparations, but the binding capacity (2·5 ±0·30 fmol/mg protein) was 50- to 75-fold lower. To identify the cells which express the GH receptor, head kidney smears were incubated with biotinylated rsbGH, followed by incubation with an avidin–biotin complex conjugated to alkaline phosphatase. The reaction with the new-fuchsin substrate gave a red precipitate, showing a specific and intense labelling in erythroblasts, polychromatophilic erythroblasts and myeloblasts. Noticeable binding was observed in myelocytes and immature granulocytes, tending to disappear at the latter stages of granulocyte maturation. Light but appreciable binding was also observed in monocytes, lymphocytes and acidophilic erythroblasts, whereas it was completely absent in proerythrocytes and erythrocytes. The proliferative action of rsbGH and recombinant human IGF-I on in vitro cultures of head kidney cells was demonstrated by a 5-bromo-2′-deoxy-uridine immunoassay. To our knowledge, this is the first report that provides suitable evidence for a role of GH as a haemopoietic growth and differentiation factor in lower vertebrate species.

Journal of Endocrinology (1995) 146, 459–467
The role of cytokines in the lipopolysaccharide-induced sick euthyroid syndrome in mice
Authors: Boelen A , Platvoet-ter Schiphorst M C , Bakker O , Wiersinga W M
Published: December 2008

To evaluate the role of cytokines in the sick euthyroid syndrome, we tried to establish an animal model of non-thyroidal illness in mice by the administration of a sub-lethal dose of bacterial endotoxin (lipopolysaccharide; LPS) which induces a variety of cytokines, including tumour necrosis factor (TNFα), interleukin-1 (IL-1α), interleukin-6 (IL-6) and interferon-γ (IFNγ). When compared with pair-fed controls, a single dose of LPS resulted in (a) systemic illness, (b) induction of TNFα and IL-6 and (c) a decrease of liver 5′-deiodinase mRNA from 4 h onwards followed by a decrease of serum tri-iodothyronine (T3) and thyroxine (T4) at 8 h and of serum free T3 (fT3) and free T4 (fT4) at 24 h; serum TSH remained unchanged.

We then studied whether a single dose or a combination of IL-1α, TNFα, IL-6 or IFNγ could induce the sick euthyroid syndrome in mice, again using pair-fed controls. None of the cytokines except IL-1α caused systemic illness, and IL-1α was the only cytokine that decreased liver 5′-deiodinase mRNA transiently. IL-1α, TNFα or IL-6 did not decrease serum T3, T4 and TSH, but administration of IFNγ decreased serum T4, T3 and fT3 in a dose-dependent manner without changes in serum TSH. Administration of all four cytokines together had no synergistic effects; observed changes were of a smaller magnitude than after LPS.

The following conclusions were reached. (1) Administration of LPS in mice is a suitable experimental model for the acute induction of the sick euthyroid syndrome. (2) Acute administration of IL-1α, TNFα or IL-6 in mice does not induce changes in thyroid hormones but IFNγ results in a dose-dependent decrease of serum T4, T3 and fT3 and IL-1α decreases liver 5′-deiodinase mRNA transiently. (3) Combined administration of IL-1α, TNFα, IL-6 and IFNγ had no synergistic effects; observed changes were of a smaller magnitude than after LPS. (4) The LPS-induced sick euthyroid syndrome is currently best explained by a direct thyroidal inhibition due to IFNγ and an extrathyroidal inhibition of liver 5′-deiodinase due to IL-1α, but other still unidentified factors seem to be involved as well.

Journal of Endocrinology (1995) 146, 475–483
Immuno-enhancement and -inhibition of GH-releasing factor by site-directed anti peptide antibodies in vivo and in vitro
Authors: Pell J M , James S
Published: December 2008

It is now well established that specific antibodies and binding proteins can potentiate rather than inhibit hormone activity. In order to investigate this phenomenon further, the current study was undertaken using a hormone with a characterised structure, in terms of receptor binding, and for which activity has already been manipulated in specific ways (prolongation of half-life, increased receptor affinity) using synthetic hormone analogues. GH-releasing factor (GRF) is a 40 or 44 residue peptide and is, together with somatostatin, responsible for the regulation of GH secretion. The effects of site-directed anti peptide antibodies were determined on the activity of GRF in vivo and in vitro as GH release. The peptide regions of GRF were: 1–14 (part of putative receptor-binding region) and 31–44 and 35–44 (sites thought to be distant from the receptor-binding region). Five sheep were administered GRF (1 μg/kg), anti peptide immunoglobulin (Ig; a calculated tenfold excess binding to GRF dose), or GRF together with anti peptide Ig (preincubated for 1 h). GRF induced a significant increase in plasma GH concentration over the next 240 min, this was abolished when GRF was administered with anti 1–14 Ig (P<0·05) and augmented (P<0·05) when GRF was administered with anti 35–44 Ig; anti 31–44 had no effect on GRF activity. Anti 35–44 Ig alone induced an increase in GH secretion which was equivalent to that for GRF alone, implying that the antibody had interacted and potentiated with endogenous GRF. The Ig effects on exogenous GRF activity were confirmed for GH release in vitro using primary cultures of sheep pituitary cells, except that anti 31–44 Ig also augmented GH release (P<0·05) when co-administered with GRF. These data are compatible with current findings on the regulation of GRF activity, namely that increases in hormone activity may be achieved by at least two mechanisms: protection from degradation (decreased clearance rate) and changed hormone–receptor interaction.

Journal of Endocrinology (1995) 146, 535–541
Levels of pro-opiomelanocortin and prolactin mRNA in the fetal sheep pituitary following hypoxaemia and glucocorticoid treatment in late gestation
Authors: Matthews S G , Challis J R G
Published: December 2008

It is well established that corticotrophin-releasing hormone and vasopressin can induce both synthesis and release of ACTH from the ovine pituitary gland, and that glucocorticoids can inhibit these responses. Changes in the abundance, localization and distribution of proopiomelanocortin (POMC) mRNA and prolactin (PRL) mRNA in the ovine fetal pituitary were examined by in situ hybridization following hypoxaemia applied in the presence or absence of concomitant cortisol in late gestation (day 135). Fetuses were distributed amongst four groups; saline-infused/normoxaemic, cortisol-infused/normoxaemic (0·3 mg/h), saline-infused/hypoxaemic and cortisol-infused/hypoxaemic. Hypoxaemia (6 h) was induced by reducing the maternal PaO2, resulting in a 6–8 mmHg decrease in fetal arterial PO2. Fetal infusions were commenced 5 h prior to and maintained throughout the treatment period. Hypoxaemia, which elevated fetal plasma ACTH and cortisol, caused a significant (P<0·05) increase in POMC mRNA in the pars distalis (PD), but was without effect on POMC mRNA in the pars intermedia (PI). Cortisol infusion attenuated the hypoxaemiainduced increase in POMC mRNA in the PD, but was without effect on non-stimulated steady-state POMC mRNA levels in either the PD or PI. PRL mRNA was only present in the PD and significantly (P<0·05) increased after cortisol infusion and hypoxaemia. In conclusion (i) POMC and PRL mRNA in the PD are increased following moderate hypoxaemia, (ii) cortisol attenuates changes in POMC mRNA but not PRL mRNA in the PD following hypoxaemia and (iii) cortisol increases PRL mRNA levels in the PD. Synthesis of POMC and PRL in the fetal PD is highly sensitive to homeostatic perturbations and glucocorticoids in late gestation.

Journal of Endocrinology (1995) 147, 139–146
Amniotic and allantoic fluid concentrations of thyroxine, 3,3′,5′-tri-iodothyronine, 3,3′-di-iodothyronine and 3′,5′-di-iodothyronine in the pig during the period of gestation
Authors: Brzezińska-Ślebodzińska E , Ślebodziński A B , Krysin E
Published: December 2008

Thyroxine (T4), 3,3′,5′-tri-iodothyronine (reverse T3; rT3) and di-iodothyronines (3,3′-T2 and 3′,5′-T2) were measured in pig amniotic fluid (AF) and allantoic fluid (Al) between 32 and 113 days of normal pregnancy. Low but measurable quantities of T4 in AF and Al (2·1 ± 0·3 and 3·2 ±0·5 nmol/l respectively) were found before the onset of fetal thyroid gland function, which indicates the maternal source of T4. The presence of rT3 (55·8 ±4·1 pmol/l in AF and 49·8 ± 5·3 pmol/l in Al), 3,3′-T2 (45·5 ± 0·6 pmol/l in AF and 49·2 ±9·2 pmol/l in Al) and 3′,5′-T2 (20·8 ±2·6 pmol/l in AF and 24·0 ± 2·2 pmol/l in Al) may be attributed to the monodeiodinase system already active in fetal pig tissues in early pregnancy, as demonstrated previously. T3 concentration was undetectable in both AF and Al. An approximately twofold increase in the levels of T4, rT3 and T2s in AF and Al at mid-gestation was observed. T4 and rT3 in AF showed a positive correlation with protein concentrations. AF rT3 concentration (but not T4) correlated with rT3 in the cord and maternal serum. The 3,3′-T2 and 3′,5′-T2 in AF and Al showed parallel changes to rT3, while the rT3/3,3′-T2 and rT3/3′,5′-T2 molar ratios remained constant. T4 concentrations in AF and Al were markedly lower than in corresponding maternal and fetal serum; the rT3 concentration in Al was equal to that in AF and two to four times lower than in fetal serum. In spite of differences between serum hormone patterns in the pig and human near term, iodothyronine concentrations in AF showed some similarities, mainly the following: undetectable T3, a strong correlation between rT3, T4 and AF total protein and the presence of 3,3′-T2 and 3′,5′-T2 in measurable levels. Comparative data for Al, except the ones in the present study in the pig, are not available.

Journal of Endocrinology (1995) 147, 245–251
Growth hormone (GH) receptor and GH-binding protein deficiency in the growth failure of potassium-depleted rats
Authors: Hochberg Z , Amit T , Flyvbjerg A , Dørup I
Published: December 2008

Potassium (K+) deficiency is associated with growth retardation in both man and experimental animals. Growth hormone (GH) administration to such animals prevents, to some extent, weight loss and selective muscle atrophy, but does not affect tail and tibia length even with supraphysiological doses. The present study was undertaken to investigate the possible effect of K+ deficiency on the hepatic GH receptor and GH-binding protein (BP). Young female Wistar rats were maintained on K+-deficient fodder and distilled water, and compared with pair-fed and ad-libitumfed control groups. After 15 days GH-BP and electrolytes were measured in sera, GH receptors were studied in liver membranes by 125I-labeled human GH binding and muscles were weighed and saved for electrolyte measurements. K+-deficient rats showed complete growth arrest compared with an intermediate weight gain of the pair-fed group. Serum K+ was very low, at 1·5 ±0·1 mmol/l, compared with the mean value of 5·3 mmol/l of control animals. Somatogenic and lactogenic receptors in liver membranes and serum GH-BP levels were significantly (P<0·05) lower in K+ deficiency, as compared with their pair-fed controls. Liver GH receptors correlated significantly (P<0·05) with serum GH-BP levels. The growth variables correlated positively with both hepatic somatogenic and lactogenic receptors and serum GH-BP levels, with correlation coefficients that were highest against serum GH-BP and lowest against liver lactogenic receptors. Serum and muscle K+ correlated significantly (P<0·05) with both liver GH receptors and serum GH-BP, with correlation coefficients that were higher against serum GH-BP. Lactogenic receptors had a lower or no correlation. It is concluded that GH receptor deficiency may be involved in the growth retardation of K+ deficiency.

Journal of Endocrinology (1995) 147, 253–258
Inhibition of 5α-reductase in genital skin fibroblasts and prostate tissue by dietary lignans and isoflavonoids
Authors: Evans B A J , Griffiths K , Morton M S
Published: December 2008

Isoflavonoids and lignans, constituents of many plant foods, have been proposed as protective agents in those populations with a low incidence of hormone-dependent cancers. They may act by their inhibition of the metabolism of growth-promoting steroid hormones. This report describes the inhibition of 5α-reductase and 17β-hydroxysteroid dehydrogenase by six isoflavonoids and two lignans in human genital skin fibroblast monolayers and homogenates, and in benign prostatic hyperplasia tissue homogenates. In genital skin fibroblasts, genistein, biochanin A and equol were the most potent inhibitors of 5α-reductase activity, each resulting in greater than 80% inhibition at a concentration of 100 μm. The IC50 values for genistein and a seven-compound mixture were approximately 35 μm and 20 μm (2·9 μm of each compound) respectively. Of the lignans, enterolactone was the most potent inhibitor. Inhibition by biochanin A was shown to be reversible. When genital skin fibroblast homogenates were used, biochanin A was found to inhibit 5α-reductase isozymes 1 and 2 to differing extents (30% and 75% respectively). Genistein was shown to inhibit 5α-reductase 2 in a non-competitive nature (Vmax and Km values without and with inhibitor were 30 and 20 pmol/mg protein per h and 177 and 170 nm respectively). All of the compounds tested inhibited 17β-hydroxysteroid dehydrogenase activity in genital skin fibroblast monolayers. When prostate tissue homogenates were used, the compounds tested were better inhibitors of 5α-reductase 1 than 2. It is possible that a life-long dietary exposure to these lignans and isoflavonoids may have a significant influence on the development of hormone-dependent tumours.

Journal of Endocrinology (1995) 147, 295–302
Two-step development of Hashimoto-like thyroiditis in genetically autoimmune prone non-obese diabetic mice: effects of iodine-induced cell necrosis
Authors: Many M-C , Maniratunga S , Varis I , Dardenne M , Drexhage H A , Denef J-F
Published: December 2008

The administration of a high iodide dose (HID; 10 μg/day) to goitrous mice is known to induce thyroid cell necrosis and inflammation, which, in most strains, is transient. In this study, we analyzed the effects of iodide in autoimmune prone non-obese diabetic (NOD) mice.

Control NOD mice fed a standard diet (MID; 1 μg I/day) or HID did not spontaneously develop thyroiditis. In NOD mice previously made goitrous, HID provoked thyroid cell necrosis and diffuse inflammation within 4 days. Inflammatory cells consisted of MHC-class II+ antigen-presenting cells, CD4+ T helper cells and CD8+ T suppressor/cytotoxic cells. After 96 days of treatment with HID, thyroiditis similar to Hashimoto's disease was obtained in 100% of the animals, with destruction of thyroid follicles, large clusters of T and B cells, and antithyroid antibodies in the plasma. When treating goitrous mice with MID, no cell necrosis was observed and no autoimmune thyroiditis was obtained. The early iodide-induced cell necrosis and inflammation may thus be considered as an important factor in the induction and persistence of autoimmune thyroiditis in individuals carrying a genetic susceptibility to autoimmune disease.

Journal of Endocrinology (1995) 147, 311–320
Prolactin receptor expression in lymphocytes from patients with hyperprolactinemia or acromegaly
Authors: Leite-de-Moraes M C , Touraine P , Kelly P A , Kuttenn F , Dardenne M
Published: December 2008

Previous reports demonstrated that prolactin receptors (PRL-R) are widely expressed on cells of the immune system. We analyzed a possible regulation of PRL-R expression on human mononucleated blood cells by prolactin (PRL) itself. PRL-R expression was analyzed by immunofluorescence on T and B lymphocytes and monocytes from peripheral blood mononucleated cells (PBMC) of patients with hyperprolactinemia or acromegaly compared with sex- and age-matched control subjects. The frequency of PRL-R positive cells and the intensity of PRL-R expression was only modified among the CD8+ T cell population of hyperprolactinemic patients with macroadenoma. No correlation was reported between PRL-R expression and circulating PRL levels. The percentage of PRL-R+ cells on B or T lymphocytes and monocytes as well as the capacity of PBMC to proliferate in response to T cell mitogens were not significantly different in bromocriptine-treated compared with untreated patients. These findings suggest that factors other than pituitary PRL play the major role in regulating PRL-R expression on cells of the immune system.

Journal of Endocrinology (1995) 147, 353–359
Changes in lipid peroxidation and free radical scavengers in the brain of hyper- and hypothyroid aged rats
Authors: Mano T , Sinohara R , Sawai Y , Oda N , Nishida Y , Mokuno T , Asano K , Ito Y , Kotake M , Hamada M , Nakai A , Nagasaka A
Published: December 2008

To determine how lipid peroxides and free radical scavengers are changed in the brain of hyper- or hypothyroid rats, we examined the behavior of lipid peroxide and free radical scavengers in the cerebral cortex of aged (1·5 years old) rats that had been made hyper- or hypothyroid by the administration of thyroxine or methimazol for 4 weeks. Concentrations of catalase, Mn-superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were increased in hyperthyroid rats compared with euthyroid rats. Concentrations of total SOD, Cu,Zn-SOD and GSH-PX were increased but that of Mn-SOD was decreased in hypothyroid animals. There were no differences among hyperthyroid, hypothyroid and euthyroid rats in the levels of coenzymes 9 or 10. The concentration of lipid peroxides, determined indirectly by the measurement of thiobarbituric acid reactants, was decreased in hyperthyroid rats but not in hypothyroid rats when compared with euthyroid animals.

These findings suggest that free radicals and lipid peroxides are scavenged to compensate for the changes induced by hyper- or hypothyroidism.

Journal of Endocrinology (1995) 147, 361–365
Inhibition of mouse placental lactogen-II release from placental cells by interleukin-1 after mid-pregnancy
Authors: Yamaguchi M , Sakata M , Ogura K , Adachi K , Mammoto A , Miyake A
Published: December 2008

The effects of interleukin (IL)-1 and granulocytemacrophage colony stimulating factor (GM-CSF), which are present in the mouse placenta, on the secretion of mouse placental lactogen (mPL)-1 and mPL-II by placental cells were tested in vitro. IL-lα and IL-1β, 2·5 nmol/l each, significantly inhibited mPL-II secretion by cells from days 9 and 12 of pregnancy, but did not affect mPL-II secretion by cells from day 7 of pregnancy or mPL-I secretion by cells from days 7, 9 or 12 of pregnancy. GM-CSF had no effect on mPL-I and mPL-II secretion by cells from days 7, 9 or 12 of pregnancy. The inhibitory effects of IL-1α and IL-1β on mPL-II secretion were completely eliminated by the addition of antibodies to IL-1α and IL-1β respectively. Western blot analysis for mPL-II indicated that IL-1α significantly reduced the intensity of the mPL-II band. Steady-state levels of mPL-II mRNA, assessed by Northern blot analysis, were reduced by incubation of placental cells from day 12 of pregnancy with 2·5 nmol/l IL-1α for 5 days. Co-incubation of 0·25 pmol/l IL-1α, 25 pmol/l IL-6, and 25 pmol/l tumor necrosis factor-α, each of which did not significantly inhibit mPL-II secretion by itself, together inhibited mPL-II secretion. These results suggest that IL-1, but not GM-CSF, is a potent inhibitor of mPL-II secretion after mid-pregnancy, and that the combined action of cytokines can inhibit mPL-II secretion.

Journal of Endocrinology (1995) 147, 423–429
Differences in cellular transport of tri-iodothyronine and thyroxine: cell cycle-dependent alteration of tri-iodothyronine uptake
Authors: Nagasawa T , Ichikawa K , Minemura K , Hara M , Yajima H , Sakurai A , Kobayashi H , Hiramatsu K , Shigematsu S , Hashizume K
Published: December 2008

Cellular and nuclear uptake of tri-iodothyronine (T3) and thyroxine (T4) was examined using the cultured cell line derived from rat liver, clone 9, and rat hepatoma, dRLH-84. The saturable cellular uptake of T3 and T4 was demonstrated in these cells. First we examined the cell cycle-dependent alteration of thyroid hormone uptake. Cellular T3 uptake was minimal in the early G1 phase and increased in the late G1 phase, reaching a maximal level in the S phase. Alterations in nuclear T3 uptake were in accordance with the changes in cellular T3 uptake. On the other hand, cellular and nuclear T4 uptake was unchanged throughout the cell cycle, suggesting the T3 specificity of the cell cycle-dependent alteration of cellular hormone transport. Next we examined the effect of sodium butyrate on the cellular transport of thyroid hormones. After treatment with 5 mm sodium butyrate, cellular and nuclear uptake of T3 was increased, reaching a maximal level (four- to sevenfold increase) after 48 h. When cells were incubated for 48 h with various concentrations of sodium butyrate, T3 uptake was enhanced by 1 mm sodium butyrate, reaching a maximal level with 5 mm. Although cellular T4 uptake was also increased after treatment with sodium butyrate, the degree and time-course of the increase were different from those of T3. The maximal increase in cellular T4 uptake (two- to threefold increase) was attained 20 h after treatment. Despite the increase in cellular T4 uptake, nuclear T4 uptake was decreased after treatment with sodium butyrate. For both T3 and T4, the enhanced cellular uptake was due to the increased Vmax without changes in the Michaelis–Menten constant. These data indicate that cellular transport of T4 is different from that of T3 in rat hepatic cells.

Journal of Endocrinology (1995) 147, 479–485
On-demand performance bonds: reducing the risk of abuse
Authors: Lurie J.
Published: December 2008

In the current economic climate, on-demand performance bonds may well be the preferred alternative to default performance bonds. This article examines drafting methods which reduce the likelihood of unfair calls against on-demand performance bonds. The author concludes that a sensible form of on-demand performance bond will ultimately benefit all parties including the issuing bank, the contractor and the beneficiary.
Successful Drilling of Oil and Gas Wells by Optimal Drilling-Fluid/Solids Control— A Practical and Theoretical Evaluation
Authors: Dahl B. , Saasen A. , Omland T. H.
Published: December 2008

Since the development of the drilling industry, the process for removing drill solids from the drilling fluid has culminated in the use of shaker screens as the primary or sole solution. It is, therefore, necessary to optimize both filtration efficiency and the screen life to hinder drilled solids from entering the drilling fluid. Optimum solids control can be obtained by using knowledge of how damage to the filtration cloth arises, of how to reduce it, and of how the particles in the circulation system influence the general picture of the drilling process. When this knowledge is accepted, established, and implemented in the drilling industry, it is possible to maintain efficient drilling.

This paper describes, in detail, the theory and field examples on how wear arises on the shaker-screen cloth. As will be shown, this knowledge has been used to increase the solids-control efficiency and to reduce the screen wear by more than 90% in several field cases where 17½-in. sections have been drilled with oil-based mud. This has been achieved by use of a different screen configuration, running with top screens with finer cut points than normal. This leads to removal of 90 to 95% of the solids from the fluid using the top deck, thereby minimizing the wear on the finer bottom-deck screens. The documentation is based on practical off-shore results from these drilling operations, including data from the drilling log, laboratory analyses of the drilling fluid, and of the particle-size distribution (PSD) of the drilling fluid. The particular focus of this article is the application of double-deck shakers.
First Hyperstatic-Riser Joint Field Tested for Deep Offshore Drilling
Authors: Poirette Y. , Guesnon J. , Dupuis D.
Published: December 2008

The riser is one of the key elements for deep offshore drilling. However, the total weight of the system increases rapidly with the water depth in the same way as the required tensioning capacity. Static loads and fatigue may become critical and threaten riser integrity. Furthermore, the natural period of the riser in the disconnected mode may also reach the wave-energy window and may seem able to put the riser into a dangerous resonant state.

A new technology developed by the L'Institut Français du Pétrole (IFP) for integrating riser joints, presented in the paper, reduces the weight of the system by up to 30% and lowers the natural period significantly. It consists of joining together all the pipes constituting the riser (main pipe and peripheral lines) in such a manner as to share the axial tension between all of them. This so-called hyperstatic-working mode, which provides an axial-load sharing between all riser lines, may be used jointly with hybrids (steel/composite) previously developed for kill and choke lines (Guesnon et al. 2002).

After the first step of riser analysis and technical studies through extensive finite-element analyses (FEAs) and computer-assisted design (CAD), a field test was decided upon to obtain information on the capacity of the technology to work properly in the operational context of a drilling rig and its capacity to maintain the hyperstatic-working mode of the riser joint in that context. The Pride Angola drillship was chosen for the test.

This paper presents the basis of the technology, describes the three phases of the field test, and comments on the first results obtained from the rig. To conclude, the technology is then put in the context of deep-water drilling, and its benefits are discussed for conventional, slender, and dual-gradient risers.
Mitochondrial Reactive Oxygen Species Are Obligatory Signals for Glucose-Induced Insulin Secretion
Authors: Leloup Corinne , Tourrel-Cuzin Cécile , Magnan Christophe , Karaca Melis , Castel Julien , Carneiro Lionel , Colombani Anne-Laure , Ktorza Alain , Casteilla Louis , Pénicaud Luc
Published: December 2008

OBJECTIVE—Insulin secretion involves complex events in which the mitochondria play a pivotal role in the generation of signals that couple glucose detection to insulin secretion. Studies on the mitochondrial generation of reactive oxygen species (ROS) generally focus on chronic nutrient exposure. Here, we investigate whether transient mitochondrial ROS production linked to glucose-induced increased respiration might act as a signal for monitoring insulin secretion.

RESEARCH DESIGN AND METHODS—ROS production in response to glucose was investigated in freshly isolated rat islets. ROS effects were studied using a pharmacological approach and calcium imaging.

RESULTS—Transient glucose increase from 5.5 to 16.7 mmol/l stimulated ROS generation, which was reversed by antioxidants. Insulin secretion was dose dependently blunted by antioxidants and highly correlated with ROS levels. The incapacity of β-cells to secrete insulin in response to glucose with antioxidants was associated with a decrease in ROS production and in contrast to the maintenance of high levels of ATP and NADH. Then, we investigated the mitochondrial origin of ROS (mROS) as the triggering signal. Insulin release was mimicked by the mitochondrial-complex blockers, antimycin and rotenone, that generate mROS. The adding of antioxidants to mitochondrial blockers or to glucose was used to lower mROS reversed insulin secretion. Finally, calcium imaging on perifused islets using glucose stimulation or mitochondrial blockers revealed that calcium mobilization was completely reversed using the antioxidant trolox and that it was of extracellular origin. No toxic effects were present using these pharmacological approaches.

CONCLUSIONS—Altogether, these complementary results demonstrate that mROS production is a necessary stimulus for glucose-induced insulin secretion.
Maternal Low-Protein Diet or Hypercholesterolemia Reduces Circulating Essential Amino Acids and Leads to Intrauterine Growth Restriction
Authors: Bhasin Kum Kum S. , van Nas Atila , Martin Lisa J. , Davis Richard C. , Devaskar Sherin U. , Lusis Aldons J.
Published: December 2008

OBJECTIVE—We have examined maternal mechanisms for adult-onset glucose intolerance, increased adiposity, and atherosclerosis using two mouse models for intrauterine growth restriction (IUGR): maternal protein restriction and hypercholesterolemia.

RESEARCH DESIGN AND METHODS—For these studies, we measured the amino acid levels in dams from two mouse models for IUGR: 1) feeding C57BL/6J dams a protein-restricted diet and 2) feeding C57BL/6J LDL receptor–null (LDLR−/−) dams a high-fat (Western) diet.

RESULTS—Both protein-restricted and hypercholesterolemic dams exhibited significantly decreased concentrations of the essential amino acid phenylalanine and the essential branched chain amino acids leucine, isoleucine, and valine. The protein-restricted diet for pregnant dams resulted in litters with significant IUGR. Protein-restricted male offspring exhibited catch-up growth by 8 weeks of age and developed increased adiposity and glucose intolerance by 32 weeks of age. LDLR−/− pregnant dams on a Western diet also had litters with significant IUGR. Male and female LDLR−/− Western-diet offspring developed significantly larger atherosclerotic lesions by 90 days compared with chow-diet offspring.

CONCLUSIONS—In two mouse models of IUGR, we found reduced concentrations of essential amino acids in the experimental dams. This indicated that shared mechanisms may underlie the phenotypic effects of maternal hypercholesterolemia and maternal protein restriction on the offspring.
Gene Silencing of Phogrin Unveils Its Essential Role in Glucose-Responsive Pancreatic β-Cell Growth
Authors: Torii Seiji , Saito Naoya , Kawano Ayumi , Hou Ni , Ueki Kohjiro , Kulkarni Rohit N. , Takeuchi Toshiyuki
Published: December 2008

OBJECTIVE—Phogrin and IA-2, autoantigens in insulin-dependent diabetes, have been shown to be involved in insulin secretion in pancreatic β-cells; however, implications at a molecular level are confusing from experiment to experiment. We analyzed biological functions of phogrin in β-cells by an RNA interference technique.

RESEARCH DESIGN AND METHODS—Adenovirus-mediated expression of short hairpin RNA specific for phogrin (shPhogrin) was conducted using cultured β-cell lines and mouse islets. Both glucose-stimulated insulin secretion and cell proliferation rate were determined in the phogrin-knockdown cells. Furthermore, protein expression was profiled in these cells. To see the binding partner of phogrin in β-cells, coimmunoprecipitation analysis was carried out.

RESULTS—Adenoviral expression of shPhogrin efficiently decreased its endogenous expression in pancreatic β-cells. Silencing of phogrin in β-cells abrogated the glucose-mediated mitogenic effect, which was accompanied by a reduction in the level of insulin receptor substrate 2 (IRS2) protein, without any changes in insulin secretion. Phogrin formed a complex with insulin receptor at the plasma membrane, and their interaction was promoted by high-glucose stimulation that in turn led to stabilization of IRS2 protein. Corroboratively, phogrin knockdown had no additional effect on the proliferation of β-cell line derived from the insulin receptor–knockout mouse.

CONCLUSIONS—Phogrin is involved in β-cell growth via regulating stability of IRS2 protein by the molecular interaction with insulin receptor. We propose that phogrin and IA-2 function as an essential regulator of autocrine insulin action in pancreatic β-cells.
Overexpression of Carnitine Palmitoyltransferase-1 in Skeletal Muscle Is Sufficient to Enhance Fatty Acid Oxidation and Improve High-Fat Diet–Induced Insulin Resistance
Authors: Bruce Clinton R. , Hoy Andrew J. , Turner Nigel , Watt Matthew J. , Allen Tamara L. , Carpenter Kevin , Cooney Gregory J. , Febbraio Mark A. , Kraegen Edward W.
Published: December 2008

OBJECTIVE—Skeletal muscle insulin resistance is associated with lipid accumulation, but whether insulin resistance is due to reduced or enhanced flux of long-chain fatty acids into the mitochondria is both controversial and unclear. We hypothesized that skeletal muscle–specific overexpression of the muscle isoform of carnitine palmitoyltransferase 1 (CPT1), the enzyme that controls the entry of long-chain fatty acyl CoA into mitochondria, would enhance rates of fatty acid oxidation and improve insulin action in muscle in high-fat diet insulin-resistant rats.

RESEARCH DESIGN AND METHODS—Rats were fed a standard (chow) or high-fat diet for 4 weeks. After 3 weeks, in vivo electrotransfer was used to overexpress the muscle isoform of CPT1 in the distal hindlimb muscles (tibialis anterior and extensor digitorum longus [EDL]). Skeletal muscle insulin action was examined in vivo during a hyperinsulinemic-euglycemic clamp.

RESULTS—In vivo electrotransfer produced a physiologically relevant increase of ∼20% in enzyme activity; and although the high-fat diet produced insulin resistance in the sham-treated muscle, insulin action was improved in the CPT1-overexpressing muscle. This improvement was associated with a reduction in triacylglycerol content, the membrane-to-cytosolic ratio of diacylglycerol, and protein kinase C θ activity. Importantly, overexpression of CPT1 did not affect markers of mitochondrial capacity or function, nor did it alter skeletal muscle acylcarnitine profiles irrespective of diet.

CONCLUSIONS—Our data provide clear evidence that a physiological increase in the capacity of long-chain fatty acyl CoA entry into mitochondria is sufficient to ameliorate lipid-induced insulin resistance in muscle.
Dipeptidyl Peptidase IV Inhibition With MK0431 Improves Islet Graft Survival in Diabetic NOD Mice Partially via T-Cell Modulation
Authors: Kim Su-Jin , Nian Cuilan , Doudet Doris J. , McIntosh Christopher H.S.
Published: December 2008

OBJECTIVE—The endopeptidase dipeptidyl peptidase-IV (DPP-IV) has been shown to NH2-terminally truncate incretin hormones, glucose-dependent insulinotropic polypeptide, and glucagon-like peptide-1, thus ablating their ability to potentiate glucose-stimulated insulin secretion. Increasing the circulating levels of incretins through administration of DPP-IV inhibitors has therefore been introduced as a therapeutic approach for the treatment of type 2 diabetes. DPP-IV inhibitor treatment has also been shown to preserve islet mass in rodent models of type 1 diabetes. The current study was initiated to define the effects of the DPP-IV inhibitor sitagliptin (MK0431) on transplanted islet survival in nonobese diabetic (NOD) mice, an autoimmune type 1 diabetes model.

RESEARCH DESIGN AND METHODS—Effects of MK0431 on islet graft survival in diabetic NOD mice were determined with metabolic studies and micropositron emission tomography imaging, and its underlying molecular mechanisms were assessed.

RESULTS—Treatment of NOD mice with MK0431 before and after islet transplantation resulted in prolongation of islet graft survival, whereas treatment after transplantation alone resulted in small beneficial effects compared with nontreated controls. Subsequent studies demonstrated that MK0431 pretreatment resulted in decreased insulitis in diabetic NOD mice and reduced in vitro migration of isolated splenic CD4+ T-cells. Furthermore, in vitro treatment of splenic CD4+ T-cells with DPP-IV resulted in increased migration and activation of protein kinase A (PKA) and Rac1.

CONCLUSIONS—Treatment with MK0431 therefore reduced the effect of autoimmunity on graft survival partially by decreasing the homing of CD4+ T-cells into pancreatic β-cells through a pathway involving cAMP/PKA/Rac1 activation.