bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of inhibin and related proteins in bovine fetal testicular and ovarian extracts: evidence for the presence of inhibin subunit products and FSH-suppressing protein
Authors: Torney A. H. , Robertson D. M. , de Kretser D. M. 
Published: December 2008

ABSTRACT
Bovine fetal gonads have been shown previously to contain inhibin bio- and immunoactivity although the ratio of these activities was markedly lower in testicular compared with ovarian extracts throughout gestation. The basis for this difference is examined in this study. Fetal testicular and ovarian high-speed supernatant preparations from bovine fetuses aged 180 to 270 days of gestation were sequentially fractionated by dye affinity chromatography, gel permeation chromatography, reversed phase highperformance liquid chromatography and preparative polyacrylamide gel electrophoresis and monitored by inhibin radioimmunoassay and in-vitro bioassay. Three immunoactive fractions were identified in testicular extracts with molecular masses of 30 kDa (Peak I), 43 kDa (Peak IIa) and 29 kDa (Peak IIb). Peak I material only was bioactive. On the basis of these characteristics, Peak I is probably 31 kDa inhibin as previously described, and Peaks IIa and lib are probably different inhibin α subunit precursor fragments.
In ovarian extracts, two bio- and immunoactive fractions were identified with molecular masses of 30 kDa (Peak I) and 29 kDa (Peak II). On the basis of size, and biological and immunological activities, the ovarian extract Peak I material is probably bovine 31 kDa inhibin, while the Peak II material is probably a novel inhibin-like protein. FSH-suppressing protein (or follistatin) bio- and immunoactivities were also identified in both testicular and ovarian extracts.
It is concluded that the low ratio of inhibin biological/immunological activity in testicular extracts is attributed to the presence of high concentrations of immunoactive α subunit precursor fragments which are low to non-detectable in ovarian extracts. These results support our previous hypothesis that, in contrast to the ovary, the inhibin α subunit is produced in excess in the fetal testis.
Journal of Endocrinology (1992) 133, 111–120
Modulation of differentiation of rat granulosa cells in vitro by interferon-γ
Authors: Xiao S. , Findlay J. K. 
Published: December 2008

ABSTRACT
The effects of recombinant rat interferon-γ (rRaIFN-γ) and rat IFN (RaIFN, a mixture of IFN-γ and -α) on basal and FSH-induced ovarian granulosa cell function were studied. Granulosa cells were harvested from diethylstilboestrol-treated immature rats and cultured (2 × 105 viable cells/well per 0·5 ml) in serumfree medium with or without treatment for 48 h. In the presence of FSH (20 ng/ml), rRaIFN-γ (10–1000 U/ml) significantly inhibited FSH-stimulated aromatase activity (76·4 ± 2·3% maximum inhibition compared with FSH treatment alone), inhibin (40·4 ± 3·7%), progesterone (47·7 ± 8·6%) and 20α-hydroxypregn-4-en-3-one (20α-OHP) (51·8±1·7%) production in a dose-dependent manner. Furthermore, rRaIFN-γ inhibited FSH- and forskolin (FSK; 30 μmol/l)-induced extracellular cAMP accumulation (46·0 ± 6·6% and 29·1 ± 7·3% respectively). The inhibitory effect of rRaIFN-γ on FSK-induced cAMP was accompanied by decreased FSK-induced aromatase activity, inhibin, progesterone and 20α-OHP production. rRaIFN-γ had no detectable effect on aromatase activity, progesterone production and 20α-OHP production in the absence of FSH, but significantly stimulated basal inhibin production by 1·5-fold. rRaIFN-γ alone also caused a small but significant increase in basal levels of cAMP. The timecourse studies showed that FSH-induced aromatase activity and inhibin production were consistently suppressed by rRaIFN-γ, FSH-induced progesterone and 20α-OHP were inhibited at 1 and 2 days and then stimulated on days 3, 4 and 5 relative to FSH alone. There was no difference in DNA content between treatment and non-treatment wells during 5 days of culture. RaIFN had similar effects to rRaIFN-γ. We conclude that IFN-γ can inhibit FSH-induced granulosa cell differentiation and that, in the absence of FSH, IFN-γ stimulated undifferentiated granulosa cells to produce more inhibin. The mechanism of its action is likely to involve changes in cAMP production.
Journal of Endocrinology (1992) 133, 131–139
Chromatographic characterization of insulin-like growth factor-binding proteins in human pregnancy serum
Authors: Wang H. S. , Chard T. 
Published: December 2008

ABSTRACT
Insulin-like growth factor-binding proteins (IGFBPs) in maternal and umbilical cord sera have been analysed by combinations of gel filtration chromatography, affinity cross-linking and electrophoresis. On gel filtration chromatography, the majority of circulating IGF-I in non-pregnant and pregnant women was present in the large molecular mass (150 kDa) binding proteins (IGFBP-3). In umbilical cord serum, by contrast, most IGF-I was present in the 40 kDa binding proteins (consisting of IGFBP-1 and IGFBP-2). Western blots demonstrated an apparent progressive attenuation of IGFBP-3 and IGFBP-2 in serum from pregnant women with an increase in IGFBP-1. After prior cross-linking with disuccinimidyl suberate, the 150 kDa fractions (IGFBP-3) from non-pregnant and pregnant serum showed a similar pattern on SDS-PAGE (several bands at different molecular masses). However, IGFBP-2 (one of the components of the 40 kDa fractions) was undetectable, even after cross-linking, in serum from pregnant women later than 8 weeks of gestational age and in a mixture of maternal serum at term delivery and serum from non-pregnant women. This suggests that serum IGFBP-2 was degraded by specific proteases present in pregnancy serum. Following acid treatment, the 150 kDa fractions from pregnancy serum were split into smaller subunits or fragments while the 40 kDa fractions remained unchanged, suggesting that the 40 kDa binding proteins are acid-stable. The present data demonstrate that IGFBP-3 is the principal IGFBP in pregnancy serum even though there is an apparent reduction in serum IGFBP-3 activity as revealed on Western blots. The absence of IGFBP-2 in serum from pregnant women may be due to degradation by proteases. In the fetal circulation IGFBP-1 and IGFBP-2 appear to be the major binding proteins for IGF-1.
Journal of Endocrinology (1992) 133, 149–159
Characterization and hormonal regulation of 24 kDa protein synthesis by the adult murine epididymis
Authors: Jimenez C. , Lefrancois A. M. , Ghyselinck N. B. , Dufaure J. P. 
Published: December 2008

ABSTRACT
The pattern of labelled proteins synthesized and secreted in vitro by the adult mouse epididymis was studied by one- and two-dimensional polyacrylamide gel electrophoresis. The presence of a major 24 kDa protein synthesized and secreted in a tissue-specific manner by the caput epididymidis was detected. For this molecular weight, two-dimensional analysis indicated several proteins including two polypeptides (pI 8·4 and 8·8) whose expression is under androgenic control. Partial amino acid sequence analysis showed a complete N-terminal identity between these two peptides. A polyclonal monospecific immune serum was raised against the two proteins. Only purified immunoglobulins precipitated them, showing that immunological affinity is restricted to these two proteins in the epididymis. Indirect immunofluorescence assay revealed specific binding of antibodies on the acrosomal region of spermatozoa isolated from the caput, corpus or cauda epididymides. Testicular spermatozoa were not labelled under the same conditions.
To investigate the physiological role of androgens in the synthesis and secretion of the 24 kDa proteins, tissue slices of epididymides from adult mice which had been castrated, or castrated then injected with testosterone were incubated with [35S]methionine. Castration and testosterone replacement kinetics revealed that alterations in 24 kDa protein synthesis follow immediately upon androgenic privation and replacement.
Journal of Endocrinology (1992) 133, 197–203
Eel insulin: isolation, characterization and stimulatory actions on [35S]sulphate and [3H]thymidine uptake in the branchial cartilage of the eel in vitro
Authors: Duan C. , Noso T. , Moriyama S. , Kawauchi H. , Hirano T. 
Published: December 2008

ABSTRACT
Our previous studies have shown that mammalian and salmon insulins stimulate sulphate uptake by cultured eel cartilage, suggesting the possible involvement of insulin in the regulation of cartilage matrix synthesis. In the present study, homologous eel insulin was isolated and characterized, and its effects on cartilage matrix synthesis and DNA synthesis were examined in vitro. Insulin was extracted from eel pancreas with acid–ethanol, and subsequently purified by isoelectric precipitation at pH 5·3, gel filtration on Sephadex G-50, and reversed-phase high-performance liquid chromatography. The amino acid composition and complete sequence (50 residues) of eel insulin revealed high homology to teleostean and mammalian insulins. The isolated eel insulin produced a more pronounced and longer lasting hypoglycaemic effect than bovine insulin in the eel. Homologous eel insulin, like bovine insulin-like growth factor (IGF-I) and insulin, stimulated sulphate uptake by cultured eel cartilage in a dose-dependent manner (16–1000 ng/ml). Combination experiments using maximal concentrations of bovine IGF-I (250 ng/ml) and increasing amounts of eel insulin (10–250 ng/ml) showed no additive effects of insulin on sulphate uptake, suggesting that insulin and IGF-I may share a common mechanism(s) of action. Eel insulin and bovine IGF-I also enhanced thymidine incorporation by eel cartilage in a dose-dependent manner (4–1000 ng/ml); eel insulin was equipotent with bovine IGF-I. These results suggest that insulin, like IGF-I, may exert direct growth-promoting actions in branchial cartilage of the eel.
Journal of Endocrinology (1992) 133, 221–230
Lipopolysaccharide is able to bypass corticotrophin-releasing factor in affecting plasma ACTH and corticosterone levels: evidence from rats with lesions of the paraventricular nucleus
Authors: Elenkov I. J. , Kovács K. , Kiss J. , Bertók L. , Vizi E. S. 
Published: December 2008

ABSTRACT
Stimulation of the immune system or experimental conditions (bacterial lipopolysaccharide (LPS) treatment) provoke a broad spectrum of physiological responses. It was recently shown that one of them is the activation of the hypothalamic-pituitary-adrenal (HPA) axis. The mechanism and the site or sites through which LPS stimulates the HPA axis are not well understood.
To establish whether the effect of bacterial LPS is related in vivo to the presence of hypothalamic hypophysiotrophic peptides (corticotrophin-releasing factor-41, arginine vasopressin, etc.), plasma ACTH and corticosterone levels were monitored in intact and sham-operated rats, and in rats with paraventricular nucleus lesions in order to remove the main source of these neuropeptides. Evidence was obtained that 4 h after treatment, LPS was able to activate the hypophysial-adrenal system in the absence of hypophysiotrophic neuropeptides of paraventricular origin.
It is suggested that, in vivo, LPS could have a direct effect on the pituitary gland or that it acts through an extrapituitary, non-paraventricular pathway to activate the HPA axis.
Journal of Endocrinology (1992) 133, 231–236
The role of calcitonin gene-related peptide in the regulation of anion secretion by the rat and human epididymis
Authors: Leung A. Y. H. , Leung P. Y. , Cheng-Chew S. B. , Wong P. Y. D. 
Published: December 2008

ABSTRACT
A study was carried out to investigate the role of the calcitonin gene-related peptide (CGRP) in the regulation of electrolyte transport in the rat and human epididymis. In monolayer cultures derived from the rat cauda epididymal cells, CGRP stimulated the short-circuit current (SCC) in a dose-dependent manner with the EC50 (concentration required to produce 50% of the response) at 15 nmol/l. This effect of CGRP was seen when the peptide was added to the basolateral aspect of the cells; apical addition having negligible effect. The CGRP-induced rise in the SCC was dependent on the presence of chloride in the bathing solution. Calcitonin had no effect on the SCC and did not affect the CGRP-induced rise in the SCC. The effect of CGRP on secretion was inhibited in a competitive fashion by the CGRP receptor antagonist CGRP(8–37). In contrast to bradykinin, angiotensin II and endothelin I, the effect of CGRP was independent of prostaglandin synthesis. Measurement of intracellular adenosine 3′:5′-cyclic monophosphate showed a time- and dose-dependent increase upon stimulation with CGRP. CGRP also stimulated the SCC in monolayers grown from the human epididymis. The current could be inhibited by apical application of the chloride channel blocker, diphenylamine-2-carboxylate. Immunoreactive CGRP was found in the epithelia of rat and human cauda epididymidis. It is suggested that CGRP may regulate the electrolyte and fluid secretion in the epididymis, thereby providing an optimal microenvironment for the maturation and storage of spermatozoa.
Journal of Endocrinology (1992) 133, 259–268
Effects of dopamine, high potassium concentration and field stimulation on the secretion of aldosterone by the perfused rat adrenal gland
Authors: Porter I. D. , Whitehouse B. J. , Price G. M. , Hinson J. P. , Vinson G. P. 
Published: December 2008

ABSTRACT
The rat adrenal cortex contains quantities of dopamine that are compatible with its function as a neurotransmitter, suggesting that locally released dopamine may act as a neuroregulator within the gland. This possibility has been tested by comparing the effects of dopamine on aldosterone secretion in the perfused adrenal with the effects of stimuli designed to provoke the release of intraglandular dopamine.
Infusion of dopamine (0·1–100 μmol/l for 10-min periods) into the isolated perfused rat adrenal gland resulted in a transient, dose-related reduction of aldosterone secretion to a minimum of approximately 50% of the basal value at 1 μmol dopamine/l (ratio of experimental to control measurements, R = 0·53 ± 0·06 (s.e.m.); n = 5). In contrast, dopamine (1–100 μmol/l) had no effect on aldosterone production by dispersed zona glomerulosa cell preparations incubated in vitro.
The effects of changes in K+ concentration (3·9–52 mmol/l) on aldosterone secretion in the perfused gland and dispersed cell preparations were also compared. A similar bell-shaped dose–response relationship was seen in both preparations between 6 and 32 mmol K+/l, with a maximum at 8·4 mmol K+/l and a return to control values with 16, 24 or 32 mmol K+/l. However, infusion of media with very high K+ concentrations (42 or 52 mmol K+/l) reduced the secretion of aldosterone by the perfused gland to approximately 50% of the basal value (R = 0·51 ± 0·05, n = 9; R = 0·49± 0·08, n = 9; respectively) but produced no change in aldosterone production by zona glomerulosa cells. Electrical field stimulation (pulse width 1 ms, 1 Hz at 60 V for 5 min) of the perfused gland also resulted in a reduction in aldosterone secretion (R = 0·66 ± 0·66, n = 6). In the presence of 1 μmol haloperidol/l, a dopamine antagonist, no effect on aldosterone secretion was seen under control conditions, but the responses to 1 μmol dopamine/l, 52 mmol K+/l and field stimulation were eliminated.
The results are consistent with the view that aldosterone secretion by the perfused adrenal gland is subject to an inhibitory dopaminergic control, which may originate from catecholaminergic neurones within the gland itself.
Journal of Endocrinology (1992) 133, 275–282
The effects of recombinant human interleukin (IL)-1α, IL-1β or IL-6 on hypothalamo-pituitary-adrenal axis activation
Authors: Harbuz M. S. , Stephanou A. , Sarlis N. , Lightman S. L. 
Published: December 2008

ABSTRACT
We have investigated the effects of recombinant human interleukin (IL)-1α, IL-1β and IL-6 on the activation of the hypothalamo-pituitary-adrenal axis. We have determined the effects of a single i.p. injection of cytokine on circulating ACTH and corticosterone levels, corticotrophin-releasing factor (CRF) mRNA in the parvocellular cells of the paraventricular nucleus and pro-opiomelanocortin (POMC) mRNA in the anterior pituitary at both 4 h and 24 h after injection. IL-1α had no effect on any of the parameters measured at either time-point. In contrast, IL-1β increased CRF mRNA in the parvocellular paraventricular nucleus and POMC mRNA in the anterior pituitary 4 h after injection. Plasma ACTH and corticosterone were increased at 4 h and circulating ACTH was still increased at 24 h after treatment with IL-1β. IL-6 had no effect on message levels but did increase circulating ACTH and corticosterone levels both 4 h and 24 h after injection. The mechanism responsible for the increase in circulating ACTH after IL-6 injection is unclear but would appear to be different from that which is activated by IL-1β which also results in increased CRF and POMC gene expression.
Journal of Endocrinology (1992) 133, 349–355
Insulin-like growth factor-I and its N-terminal modified analogues induce marked gut growth in dexamethasone-treated rats
Authors: Read L. C. , Tomas F. M. , Howarth G. S. , Martin A. A. , Edson K. J. , Gillespie C. M. , Owens P. C. , Ballard F. J. 
Published: December 2008

ABSTRACT
The effects of insulin-like growth factor-I (IGF-I) on the gut of 150 g dexamethasone-treated rats were compared with those of two analogues with reduced affinity for IGF-binding proteins, des(1–3)IGF-I and LR3IGF-I, an N-terminal-extended variant. Administration of IGF-I for 7 days to rats made catabolic by co-treatment with dexamethasone induced a dose-dependent increase in total gut weight, with the highest dose of IGF-I (695 μg/day) increasing gut weight by up to 60%, and gut weight as a fraction of body weight by up to 32%. Effects were apparent in all regions of the gut examined, including the stomach, small intestine and colon. Histological and biochemical analyses of the intestine showed that cross-sectional mass, rather than gut length, was increased, and proportional increases in wet weight, protein and DNA content per unit length were measured in both the mucosa and muscularis layers. The rate of duodenal protein synthesis measured on day 7 of treatment was not increased by IGF-I treatment. The IGF-I analogues had qualitatively similar effects to IGF-I, but were consistently severalfold more potent, providing evidence that IGF-binding proteins reduce the biological activity of exogenous IGF-I in the gut. The results indicate that the gut is one of the most sensitive IGF-I target tissues, and that potency in vivo correlates with a reduced interaction with IGF-binding proteins.
Journal of Endocrinology (1992) 133, 421–431
Exogenous gonadotrophin-releasing hormone (GnRH) stimulates LH secretion in male monkeys (Macaca fascicularis) treated chronically with high doses of a GnRH antagonist
Authors: Weinbauer G. F. , Hankel P. , Nieschlag E. 
Published: December 2008

ABSTRACT
We reported previously that after a single injection of a gonadotrophin-releasing hormone (GnRH) antagonist to male monkeys, exogenous GnRH stimulated LH secretion in a time- and dose-dependent manner, indicating that GnRH antagonist-induced blockade of LH secretion resulted from pituitary GnRH receptor occupancy. The present study was performed to investigate whether GnRH can also restore a blockade of LH and testosterone secretion during chronic GnRH antagonist administration. Four adult male cynomolgus monkeys (Macacafascicularis) received daily s.c. injections of the GnRH antagonist [N-Ac-d-pCl-Phe1,2,d-TRP3,d-Arg6,d-Ala10]-GnRH (ORG 30276) at a dose of 1400–1600 μg/kg for 8 weeks. Before the GnRH antagonist was given and during weeks 3 and 8 of treatment, pituitary stimulation tests were performed with 0·5, 5, 50 and 500 μg synthetic GnRH, administered in increasing order at intervals of 24 h. At 8 weeks, a dose of 1000 μg GnRH was also given. All doses of GnRH significantly (P < 0·05) stimulated serum concentrations of bioactive LH (3- to 8-fold) and testosterone (2·6- to 3·8-fold) before the initiation of GnRH antagonist treatment. After 3 weeks of GnRH antagonist treatment, only 50 and 500 μg GnRH doses were able to increase LH and testosterone secretion. Release of LH was significantly (P < 0·05) more elevated with 500 μg compared with 50 μg GnRH. After 8 weeks, only the highest dose of 1000 μg elicited a significant (P < 0·05) rise in LH secretion. Basal hormone levels just before the bolus injection of GnRH were similar (P > 0·10–0·80). This finding eliminated the possibility that the increasing doses of GnRH had primed the pituitary thereby resulting in higher stimulatory effects of the larger doses of GnRH.
In conclusion, the present data indicate that, even after prolonged exposure to a GnRH antagonist, the pituitary retains some degree of responsiveness to GnRH. This observation supports the view that the inhibitory effects of chronic GnRH antagonist treatment are also mediated, at least in part, by occupancy of the pituitary GnRH receptor rather than by receptor down-regulation.
Journal of Endocrinology (1992) 133, 439–445
Release of interleukin-6 by human thyroid epithelial cells immortalized by simian virus 40 DNA transfection
Authors: Kennedy R. L. , Jones T. H. , Davies R. , Justice S. K. , Lemoine N. R. 
Published: December 2008

ABSTRACT
Interleukin-6 (IL-6) has actions on a variety of endocrine tissues. The cytokine is secreted by cells of the anterior pituitary and endocrine pancreas and has recently been shown to be produced by cultures of thyroid epithelial cells. In this study we have examined some of the factors which regulate IL-6 release from an immortalized human thyroid line (HTori3).
IL-6 release over 24 h was stimulated by TSH (5000 μU/ml), by forskolin (0·01 mmol/l), by fetal calf serum (1–20%) and by epidermal growth factor (20 ng/ml). Stimulation was also apparent with γ-interferon and with tumour necrosis factor at concentrations known to enhance class II major histocompatibility antigen expression by thyroid epithelium. The most potent factor tested was interleukin-1 (IL-1), which controls IL-6 release from other cell types. Threefold stimulation was found with 1 U/ml rising to 350-fold with 1000 U/ml. The effect of IL-1 took 2 h to develop and was blocked by cycloheximide (100 μmol/l). Stimulation was not markedly inhibited by pertussis toxin. Many of the actions of IL-1 are mediated by prostaglandin E2 (PGE2). At concentrations as low as 30 nmol/l, PGE2 stimulated IL-6 release but the maximum stimulation obtained with PGE2 was only threefold. The effect of IL-1 was not inhibited by indomethacin.
These data provide further evidence that IL-6 is produced by human thyrocytes. The effect of IL-1 has not been demonstrated previously. Stimulation of IL-6 release by IL-1 did not appear to be mediated by prostaglandin. IL-6 may influence hormone release from the thyroid as it does in other tissues. High concentrations of IL-6 in the thyroid may increase infiltration by, and activation of, lymphocytes in patients with autoimmune thyroid disease.
Journal of Endocrinology (1992) 133, 477–482
Uptake of l-tri-iodothyronine by human cultured trophoblast cells
Authors: Mitchell A. M. , Manley S. W. , Mortimer R. H. 
Published: December 2008

ABSTRACT
We investigated the uptake of l-tri-iodothyronine (T3) by cultured human trophoblast cells. Uptake was time-dependent, initially linear and approaching equilibrium after 60 min with an approximate half-time of 13 ± 4·5 min (mean ± s.e.m., n = 4). It had a non-saturable component accounting for about 50% of total uptake. We demonstrated a single saturable T3 uptake mechanism with a calculated Michaelis constant (Km) of 755 ± 145 nmol/l (n = 11–13) and a corresponding maximum velocity of 28·8 ± 5·3 pmol/min per mg protein (n = 11–13). The Km value was similar to those reported in other tissues.
Journal of Endocrinology (1992) 133, 483–486