bluuebunny/crossref_metadata_2025 huggingface dataset:
Opposite effects of glucocorticoid on hepatic 11 β-hydroxysteroid dehydrogenase mRNA and activity in fetal and adult sheep
Authors: Yang K , Berdusco E T M , Challis J R G
Published: December 2008

The level of 11 β-hydroxysteroid dehydrogenase (11β-HSD) mRNA in the fetal sheep liver increases dramatically between day 130 and term (term=day 145), but the causal factors remain unknown. The present study was designed to determine the effects of exogenous glucocorticoid on the fetal hepatic 11 β-HSD gene expression. Dexamethasone (dex; 2 μg/min over 15 min every 2 h) or saline was infused into chronically-catheterized fetal sheep at day 130 of gestation for 4 days. At the end of infusion, the lower right lobe of the liver was collected, total cellular RNA extracted and subjected to Northern blot analysis. It was found that the level of the hepatic 11 β-HSD mRNA in dex-treated fetuses was about four times higher than that in the saline-treated controls. To examine whether changes occur in the response of hepatic 11 β-HSD gene expression to glucocorticoids in adulthood, we also treated non-pregnant ewes with dex (10 mg/day) for 4 days. By contrast, this treatment regime in adult sheep produced a small but significant decrease in hepatic 11 β-HSD mRNA levels.

We also determined whether age-specific changes in the hepatic level of 11 β-HSD mRNA following dex treatment were reflected in the level of 11 β-HSD enzyme activity. Hepatic 11 β-HSD activity was determined by a standard in vitro conversion assay using cortisol and cortisone as physiological substrates. In both fetal and adult livers, 11-oxoreductase activity (cortisone→cortisol) was predominant. Following dex treatment, there was a significant increase in the fetal hepatic level of both 11β-dehydrogenase (cortisol→cortisone) and 11-oxoreductase activities. Furthermore, the C-11 activation index, an indicator of glucocorticoid net gain, was also increased in the fetal liver by dex. In marked contrast, dex treatment in the adult did not alter the C-11 activation index though it produced a significant decrease in the hepatic level of both 11 β-dehydrogenase and reductase activities. In summary, these results indicate that (1) exogenous glucocorticoid exerts opposite effects on hepatic 11 β-HSD gene expression in fetal and adult sheep; (2) dex-induced age-specific changes in the level of 11β-HSD mRNA are carried though to the level of 11β-HSD protein; and (3) since 11 β-HSD reductase activity is predominant in both fetal and adult sheep livers, the liver may be a potential extra-adrenal source of cortisol. Furthermore, we speculate that (1) the dramatic increase in the fetal hepatic 11 β-HSD mRNA level at term may be due to the elevated fetal plasma concentration of glucocorticoid; and (2) glucocorticoid-induced increases in the fetal hepatic 11β-HSD gene expression and the resultant increase in the C-11 activation index during the last days of fetal life may play a crucial role in fetal organ maturation and in the endocrine mechanisms leading to parturition.

Journal of Endocrinology (1994) 143, 121–126
Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on bovine granulosa cell steroidogenesis in vitro
Authors: Gong J G , McBride D , Bramley T A , Webb R
Published: December 2008

Our previous studies have demonstrated that physiological concentrations of metabolic hormones, including recombinant bovine somatotrophin (BST), insulin-like growth factor-I (IGF-I) and insulin, can significantly stimulate the proliferation of bovine granulosa cells cultured under serum-free conditions. In this study we investigated the effects of these factors on bovine granulosa cell steroidogenesis using the same culture system. Bovine granulosa cells were obtained from antral follicles classified into three size classes: small, <5 mm; medium-sized, 5–10 mm and large, >10 mm in diameter.

Whilst not affecting steroidogenesis by granulosa cells from small and medium-sized follicles, BST (10–1000 ng/ml) stimulated the secretion of both oestradiol and progesterone by granulosa cells from large follicles in a dose-dependent manner. Insulin (1–1000 ng/ml) and IGF-I (10–1000 ng/ml) stimulated the secretion of oestradiol and progesterone by granulosa cells from all three size categories of follicles in a dose-dependent manner. FSH (200 ng/ml) alone increased progesterone secretion by granulosa cells from all three size classes of follicles, but had no effect on oestradiol secretion by granulosa cells. Both IGF-I (200 ng/ml) and insulin (30 ng/ml) acted in synergy with FSH (200 ng/ml) to stimulate steroidogenesis by granulosa cells from all three size categories of follicles, but no such interaction was observed between BST (50 ng/ml) and FSH (200 ng/ml).

In conclusion, BST, IGF-I and insulin significantly influence the steroidogenic activity of bovine granulosa cells cultured under serum-free conditions. However, unlike their effects on cell proliferation, the minimal effective concentrations of these factors required to stimulate granulosa cell steroidogenesis were higher than those observed in our previous studies in vivo.

Journal of Endocrinology (1994) 143, 157–164
Regulation of ovine fetal pituitary function by corticotrophin-releasing hormone, arginine vasopressin and cortisol in vitro
Authors: Lü F , Yang K , Challis J R G
Published: December 2008

Parturition and fetal organ maturation in sheep are associated with increased activity of the fetal hypothalamic-pituitary-adrenal (HPA) axis during late pregnancy. However, the factors responsible for HPA activation remain unclear. In the fetal pituitary, levels of pro-opiomelanocortin (POMC) mRNA increase, but the numbers of binding sites for corticotrophin-releasing hormone (CRH), and ACTH responsiveness to exogenous CRH decline during the last 20 days of pregnancy. We have examined regulation of CRH binding, pituitary ACTH responsiveness, and levels of POMC mRNA in cultures of adenohypophysial cells from term fetal sheep. After a 4-day stabilization period, output of immunoreactive (ir) ACTH was increased over 48 h in a dose-dependent fashion by both CRH and arginine vasopressin (AVP) but decreased by cortisol. Subsequent output of ir-ACTH to a 3-h challenge with 100 nm CRH was attenuated after pretreatments with CRH, AVP or cortisol; the effect of CRH being greater than that of cortisol or AVP. At the end of 48 h of treatment with CRH, AVP or cortisol, there was a 40–50% reduction in the number of CRH-binding sites, but the levels of POMC mRNA decreased significantly only after cortisol treatment and were not altered significantly by CRH or AVP.

We conclude that under the conditions of these experiments, CRH and AVP increase ir-ACTH output without increasing the level of steady-state POMC mRNA, but may contribute to loss of pituitary responsiveness to CRH by down-regulation of CRH receptor number. Cortisol exerts negative feedback on POMC mRNA and decreases the number of CRH receptors. Thus, any one or all of CRH, AVP and cortisol could be responsible for the decline in CRH binding in the fetal sheep pituitary during late pregnancy. Although CRH and AVP may affect secretion of ir-ACTH, the present results do not support a role for these neuropeptides in affecting the level of POMC mRNA in the fetal sheep pituitary.

Journal of Endocrinology (1994) 143, 199–208
The time since castration influences the effects of short-term starvation on gonadotrophin secretion in male rats
Authors: Bergendahl M , Huhtaniemi I
Published: December 2008

Short-term starvation suppresses the pituitary-testicular function in rats, evidently through inhibition of gonadotrophin-releasing hormone (GnRH) release. However, when gonadotrophin secretion is strongly enhanced, e.g. after castration, starvation does not suppress gonadotrophins. To test whether the time since castration affects the pituitary response to starvation, adult male rats were totally deprived of food for five days (only water allowed) immediately (acute castration) or two weeks after castration (chronic castration). The pituitary contents of GnRH receptors were decreased by starvation in sham-operated animals, unaffected in acutely castrated rats, but increased in chronically castrated animals, in comparison with appropriate controls (P<0·01). Castration per se increased steady-state mRNA levels of the common α-chain and the LH and FSH β-chains in all groups studied. The only consistent effect of starvation on these parameters was the 1·7 to 2-fold increase in the pituitary content of LH β-subunit mRNA in acutely and chronically castrated rats (P<0·01). Starvation alone suppressed LH secretion, acute castration eliminated this effect, but in chronically castrated rats, the starvation effect was stimulatory. Starvation did not affect FSH secretion in sham-operated and acutely castrated rats, but after chronic castration, the effect was stimulatory. In conclusion, the overall effect of starvation on gonadotrophins shifts gradually after castration from suppression, in sham-operated rats, to stimulation, in chronically castrated animals. Parallel changes in pituitary GnRH receptors suggest similar changes in GnRH secretion. Hence, starvation has both negative and positive effects on the GnRH-gonadotrophin-axis. The negative effect is evidently androgen-dependent and dominates in testes-intact animals. After chronic castration, only the positive, non-androgen dependent, stimulatory effect remains.

Journal of Endocrinology (1994) 143, 209–219
In vivo diuretic effect of a new non-peptide arginine vasopressin antagonist, OPC-31260, in conscious rats
Authors: Tsuboi Y , Ishikawa S , Fujisawa G , Okada K , Saito T
Published: December 2008

The present study was undertaken to determine whether a non-peptide arginine vasopressin (AVP) antagonist (5-dimethylamino - 1- [4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetrahydro-1H-benzazepine; OPC-31260) antagonizes the antidiuretic action of endogenous and exogenous AVP in conscious rats. OPC-31260, given orally at a dose of 5 mg/kg or higher, increased urinary volume (UV) and reduced urinary osmolality (Uosm) in a dose-dependent manner, in rats acutely denied access to water. Minimal Uosm was obtained 1–2 h after oral administration of OPC-31260. OPC-31260 caused sustained water diuresis for more than 12 h when water was available ad libitum since OPC-31260 (30 mg/kg) reduced Uosm to less than 230 mOsmol/kg H2O, significantly less than the control value of 600 mOsmol/kg H2O. Water deprivation for 24 h increased plasma AVP levels to 7·2 pmol/l and increased Uosm to 2160 mOsmol/kg H2O. In such water-deprived rats, oral administration of OPC-31260 at 100 mg/kg was diuretic; it markedly increased free water clearance and decreased Uosm to 202 mOsmol/kg H2O.

In homozygous Brattleboro rats (with inherited AVP deficiency), given free access to water, subcutaneous infusion of the V2 agonist 1-deamino-8-D-AVP (dDAVP) at a rate of 1 ng/h markedly decreased UV to 12.6 from 148·7 ml/day and increased Uosm to 1762 from 231 mOsmol/kg H2O. OPC-31260 (30 mg/kg) promptly increased UV and reduced Uosm to levels similar to those before the administration of dDAVP; repeated OPC-31260 treatment had sustained effects. These results indicate that OPC-31260 is an orally effective non-peptide AVP antagonist to the antidiuretic action of AVP in the conscious rat.

Journal of Endocrinology (1994) 143, 227–234
Stimulation by insulin-like growth factor-I of creatine kinase activity in skeletal-derived cells and tissues of male and female rats
Authors: Sömjen D , Kaye A M
Published: December 2008

Insulin-like growth factor-I (IGF-I) has been reported to mediate the effects of oestradiol-17β in the osteoblast-like osteosarcoma cell line ROS 17/2·8 and to stimulate directly cell proliferation in cell cultures derived from rat calvaria. Few data are available on the role of IGF-I in androgen stimulation of cultured skeletal cells and in oestrogen and androgen stimulation of bone and cartilage in vivo. The purpose of the present study was to compare the effect of IGF-I in rats in vivo with its effect in vitro on calvarial bone cells from females (responding only to oestrogens) and from males (responding only to androgens, such as testosterone and dihydrotestosterone). We found that IGF-I stimulated, in a dose- and time-dependent manner, the specific activity of creatine kinase (CK, a marker of skeletal cell division), in both female and male calvarial bone cells, in ROS 17/2·8 cells and in epiphyseal cartilage cell cultures. Maximal stimulation occurred at 30 or 100 nm within 1–2 h after stimulation. In ROS 17/2·8 cells, IGF-I stimulated [3H]thymidine incorporation, after 22 h of treatment, in parallel with CK activity. IGF-II, at higher doses than IGF-I (maximal stimulation at 300 nm), stimulated CK specific activity in female- and male-derived calvarial cell cultures. When IGF-I (50 nm) was applied together with oestradiol-17β (30 nm) or with dihydrotestosterone (300 nm) there was no additional response in the cultures. IGF-I injection (1·5 μg) into immature female or male rats resulted in a time-dependent stimulation of CK specific activity in epiphyses and diaphyses starting at 2 h. Injection of IGF-I (1·5 μg) together with either 5 μg oestradiol-17β to females or 50 μg dihydrotestosterone to males did not change the pattern or the extent of response to IGF-I. The response of both male- and female-derived bone cells to IGF-I suggests that it could play a role in the effects of androgens as well as oestrogens in bone and cartilage.

Journal of Endocrinology (1994) 143, 251–259
Regulation of parathyroid hormone-related protein production in a human lung squamous cell carcinoma line
Authors: Rizzoli R , Feyen J H M , Grau G , Wohlwend A , Sappino A P , Bonjour J-Ph
Published: December 2008

The synthesis and release of parathyroid hormone-related protein (PTHrP) could be influenced in a paracrine or autocrine manner by substances present around or inside tumours, such as bone or stromal cell-derived cytokines, factors produced by the tumour itself or by peritumoural inflammatory cells. We investigated the effects of various cytokines known to be synthesized by osteoblasts, stromal cells, leucocytes or cancer cells, on PTHrP production by the human lung squamous cell carcinoma line BEN. The influence of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) was studied, and compared with those of insulin-like growth factors-I and -II (IGF-I, IGF-II), or macrophage- or granulocyte-macrophage colony-stimulating factors (M-CSF, GM-CSF). TNFα caused a 1·9 ±0·1-fold increase in immunoreactive PTHrP production, which was maximal by 24 h of incubation. IL-6 caused a 2·3 ± 0·2-fold increase, which was maximal by 16 h. These effects, which were time- and concentration-dependent, were blocked by monoclonal antibodies raised against the corresponding cytokine. An increase of PTHrP mRNA was found in IL-6-treated cells. IGF-I and IGF-II increased PTHrP production by 2·0± 0·3- and 2·3 ±0·1-fold respectively. Neither M-CSF nor GM-CSF altered PTHrP production up to 64 h of incubation. PTHrP production was not affected by varying extracellular calcium concentrations, but was decreased by incubation with 100 nmol/l dexamethasone. These results indicate that PTHrP production is influenced by various cytokines, suggesting that they may play a role in the onset of hypercalcaemia during the course of malignant disease, and/or the development and extension of bone metastases, through their effect on PTHrP.

Journal of Endocrinology (1994) 143, 333–341
Quantitative studies on the effect of prostacyclin on freshly isolated rat osteoclasts in culture
Authors: Adebanjo O A , Pazianas M , Zaidi A , Shankar V S , Bascal Z A , Dacke C G , Huang C L-H , Zaidi M
Published: December 2008

Prostaglandins exert marked but transient inhibitory effects on bone resorption. The present study examines the effects of prostacyclin (0·15 to 25 μm) on the morphology of freshly disaggregated rat osteoclasts. An area descriptor, p, represented changes in total cell spread area, and a motility descriptor, μ, represented overall changes in cell motility. The application of prostacyclin intercepted the trend of an increasing cell spread area with time and produced a transient reduction of ρ, an R effect. Its magnitude depended upon concentration and was marked at 25 μm prostacyclin. The subsequent recovery (+0·8/min) of ρ at this concentration resembled the persistent spreading seen in the absence of the agonist. There was also a sustained decrease in μ to approximately 60% of its pretreatment value (a Q effect) following the application of 25 μm prostacyclin. The extracellular application of 20 mm [Ca2+] produced a similarly transient cell retraction preceded by a rise of cytosolic [Ca2+], but without a corresponding decrease in μ. In contrast, prostacyclin did not elevate cytosolic [Ca2+], suggesting the triggering of an alternative transduction pathway. A fully reversible retraction together with incomplete quiescence may explain the transience characteristic of the antiresorptive action of prostacyclin.

Journal of Endocrinology (1994) 143, 375–381
Differential regulation of prolactin receptor mRNA expression in rat liver and kidney by testosterone and oestradiol
Authors: Sakaguchi K , Ohkubo T , Sugiyama T , Tanaka M , Ushiro H , Nakashima K
Published: December 2008

Prolactin (PRL) exerts a wide variety of physiological effects on mammalian tissues through its receptor (PRL-R) on the target cells. PRL-R in rat tissue consists of two isoforms, the long and the short form, and the regulatory mechanisms of their mRNA expression in tissues are complex and diverse. The present study reports the differential regulation of PRL-R mRNA expression in rat liver and kidney by testosterone and oestradiol. Using Northern blot analysis, short form PRL-R mRNA was clearly detected in female rat liver and male rat kidney, and long form PRL-R mRNA was faintly observed only in female rat liver. However, the reverse transcription-polymerase chain reaction method enabled efficient analysis of mRNA levels in short and long forms of PRL-R in the liver and kidney of both male and female rats. The mRNA levels for the long and short forms of PRL-R were depressed in the liver of male rats but not in that from female rats during sexual maturation. Castration of male rats resulted in the induction of the mRNAs for these two forms of PRL-R in the liver. Testosterone, but not oestradiol, completely blocked the induction by castration of liver PRL-R gene expression. In kidney, in contrast, mRNA levels for both forms of PRL-R were depressed in female rats but not in male rats after sexual maturation. Administration of oestradiol, but not of testosterone, caused marked repression of short form PRL-R mRNA, particularly in the kidney of male rats. The levels of long form PRL-R mRNA in the kidney was less affected by the administration of oestradiol. These results have suggested that the expression of PRL-R mRNAs in rat liver and kidney is differentially regulated by testosterone and oestrogen.

Journal of Endocrinology (1994) 143, 383–392
Effects of acute and repeated intravenous administration of L-692,585, a novel non-peptidyl growth hormone secretagogue, on plasma growth hormone, IGF-1, ACTH, cortisol, prolactin, insulin, and thyroxine levels in beagles
Authors: Jacks T , Hickey G , Judith F , Taylor J , Chen H , Krupa D , Feeney W , Schoen W , Ok D , Fisher M , Wyvratt M , Smith R
Published: December 2008

L-692,585 is a 2-hydroxypropyl derivative of L-692,429, both novel non-peptidyl growth hormone (GH) secretagogues. The effects of single and repeated intravenous administration of L-692,585 on serum or plasma GH and other hormones in beagles were evaluated. In a balanced 8-dog dose-ranging study, compared to the saline control with a mean (± s.e.m.) after-dose serum GH peak of 6·1 ± 1·3 ng/ml, L-692,585 significantly increased (P<0·05) peak GH concentrations 4·3-fold (32·5 ± 7·0 ng/ml) at a dose of 0·005 mg/kg, 7-fold (49·4±10·6 ng/ml) at a dose of 0·02 mg/kg, and 21-fold (134·3±29·0 ng/ml) at a dose of 0·10 mg/kg. Total GH release, expressed as area under the curve, showed a similar dose-dependent increase. Peak GH levels were recorded at 5 or 15 min after dosing with the levels returning to near baseline by 90 min. Serum cortisol levels were increased above saline control levels in a dose-dependent manner; however, the increases were modest compared to the GH increases. Based on peak responses and total GH release, L-692,585 was 10- to 20-fold and 2- to 2·5-fold more potent than L-692,429 and the growth hormone releasing peptide, GHRP-6, respectively. When L-692,585 was administered once daily for 14 consecutive days at 0, 0·01 or 0·10 mg/kg to each of 6 dogs, peak plasma GH levels and total GH release on days 1, 8 and 15 significantly increased in a dose-dependent manner, and no desensitization was evident. Mean peak levels ranged from 42 to 50 ng/ml and from 64 to 100 ng/ml for the 0·01 and 0·10 mg/kg doses, respectively. Six hours after dosing, IGF-1 levels were increased on each of the sampling days. Mean adrenocorticotrophic hormone and cortisol levels were modestly elevated transiently on each of the sampling days, while prolactin, insulin and thyroxine levels were unaltered over the course of the study.

These studies demonstrated that L-692,585 is a potent GH secretagogue that induces an acute, transient increase in GH levels. The magnitude of the response is not down-regulated following repeated daily administration for 14 days. IGF-1 levels are increased for an extended period following each treatment.

Journal of Endocrinology (1994) 143, 399–406
Modulation of epidermal growth factor binding and receptor gene expression by hormones and growth factors in sheep pituitary cells
Authors: Chaidarun S S , Eggo M C , Stewart P M , Sheppard M C
Published: December 2008

Epidermal growth factor (EGF) is a potent mitogen for sheep pituitary cells but the factors controlling the binding and expression of EGF and its receptor (EGFR) in the pituitary are poorly understood. Regulation of EGF binding and EGFR gene expression may determine cellular responsiveness to EGF and could play a role in neoplastic development. Scatchard analysis of 125I-EGF binding in cultured sheep pituitary cells revealed two receptor binding sites (high affinity class of 2·5± 0·5 × 103 receptors/cell with a dissociation affinity constant (Kd) of 3·2± 0·7 × 1010m and low affinity class of 3·3 ±1·0 × 104 receptors/cell with a Kd of 71 ±1·3 × 10−9 m). Exposure of the cultured cells to some target gland hormones of the pituitary (oestrogen, tri-iodothyronine and hydrocortisone), pituitary growth factors (EGF, basic fibroblast growth factor, transforming growth factor-β and a tumour-promoting phorbol ester (TPA) resulted in an increase in the binding affinity of the high affinity receptors while reducing the receptor number and also a reduction of EGFR mRNA levels, shown by Northern blot analysis. In contrast, forskolin, an activator of adenylate cyclase, showed no significant effect on EGF binding and receptor gene expression. We conclude that the EGFR in normal pituitary cells can be modulated by several hormones and other growth factors at both receptor binding and mRNA levels. Transmodulation of EGFR by hormones and growth factors in the pituitary may be one of the regulatory mechanisms controlling the balance of normal pituitary growth and function. Defects in this regulatory system could have a role in the multistep process of pituitary tumourigenesis.

Journal of Endocrinology (1994) 143, 489–496
Differential metabolic requirement for initiation and augmentation of insulin release by glucose: a study with rat pancreatic islets
Authors: Ishihara F , Aizawa T , Taguchi N , Sato Y , Hashizume K
Published: December 2008

Insulin release, glucose utilization (3H2O formation from [5-3H]glucose), and glucose oxidation (14CO2 formation from [4C(U)] glucose) were determined in pancreatic islets from 96-h fasted rats at 37 ° C and those from fed rats at 22 ° C, using the islets from fed rats incubated at 37 ° C as controls. In the islets from 96-h fasted rats and those from fed rats incubated at 22 ° C, we could not demonstrate significant insulin release in response to high glucose concentrations of up to 16·7 mmol/l. However, 16·7 mmol/l glucose clearly augmented insulin release caused by a depolarizing concentration (50 mmol/l) of K+ in these islets: i.e. 16·7 mmol/l glucose plus 50 mmol/l K+ produced significantly greater insulin release than 50 mmol/l K alone. Glucose utilization and oxidation by the islet cells were suppressed by 96-h fasting of the rats or by lowering the incubation temperature to 22 ° C, and depolarization with K at 50 mmol/l did not at all augment glucose utilization and oxidation by the islets. Thus we conclude that reduction of glucose metabohsm in islets from fasted rats and in those incubated at low temperature eliminated initiation, but not augmentation, of insulin release by 16·7 mmol/l glucose. The data indicate that the metabolic threshold for the initiation of insulin release is significantly higher than it is for the augmentation of release by glucose.

Journal of Endocrinology (1994) 143, 497–503
A vitamin D analogue KH 1060 activates the protein kinase C– c-fos signalling pathway to stimulate epidermal proliferation in murine skin
Authors: Gniadecki R
Published: December 2008

The cellular signalling pathways of a potent 20-epi-22-oxa vitamin D3 analogue (KH 1060) were examined in vivo in a hairless mouse model. Seventy two hours after a single topical application of KH 1060 a thickening of the epidermis (from 24·8 ±1·2 μm at 0·01 pmol/cm2 KH 1060 to 124·2 ± 6 μm at 5 pmol/cm2 KH 1060, P<0·001) was elicited due to epidermal hyperproliferation. This effect could be blocked by topical 2·5 μmol/cm sphingosine, an inhibitor of protein kinase C. Two hours after topical application of 2·5 pmol/cm2 KH 1060 a translocation of protein kinase C activity from cytoplasm to the membrane fractions was observed. Moreover, using a reverse-transcription polymerase chain reaction technique, a transient upregulation of c-fos gene expression was seen 2 hours after topical treatment with KH 1060. The expression of c-fos was dependent on protein kinase C activation, since after pretreatment with the protein kinase C blocker sphingosine, c-fos messenger RNA was not detected. These findings strongly suggest that KH 1060 stimulates epidermal growth through activation of the protein kinase C - c-fos signalling axis in vivo.

Journal of Endocrinology (1994) 143, 521–525
Characterization of vasopressin and oxytocin receptors in an Australian marsupial
Authors: Bathgate R A D , Sernia C
Published: December 2008

In this study arginine vasopressin (AVP) and oxytocin (OT) receptors have been characterized in the brushtail possum. AVP receptors were characterized using [3H]AVP and the radioiodinated AVP V1a receptor antagonist 125I-labelled [(C6H5-CH2CO)-O-methyl-d-Tyr-Phe-Gln-Asn-Arg-Pro-Arg-Tyr- NH2] while OT receptors were characterized using the radioiodinated OT receptor antagonist 125I-labelled d(CH2)5[Tyr(Me)2,Thr4,Orn8, Tyr-NH29]-vasotocin. The receptor affinities and densities have been compared with the rat AVP and OT receptors. Low densities of OT receptors were present in the possum ovary and kidney. High densities of AVP-binding sites were found in the possum adrenal, testis, mesenteric artery, ovary and renal medulla and lower densities in the possum liver. The AVP-binding sites showed marked differences in ligand-binding characteristics from the rat AVP V1a and V2 receptors. Receptor affinities were similar between tissues, except for a distinctly lower value in the renal medulla. It is concluded that the brushtail possum expresses AVP receptors with distinct ligand specificities from those of the rat AVP V1a and V2 receptors.

Journal of Endocrinology (1995) 144, 19–29
Peptides related to thyrotrophin-releasing hormone are degraded in seminal plasma by an enzyme similar to prolyl endopeptidase
Authors: Siviter R J , Cockle S M
Published: December 2008

A TRH-like peptide, fertilization-promoting peptide (FPP), is present in high concentrations in mammalian prostate and semen and enhances the fertilization potential of spermatozoa. In this study, we have examined the properties of the enzyme that degrades TRH and FPP in rabbit seminal plasma. The enzyme responsible had a pH optimum of approximately 7·0, was inhibited by serine (di-isopropyl flurophosphate) and thiol (N-ethylmaleimide) protease inhibitors, bacitracin and concentrations of Zn2+ naturally present in seminal plasma: these functional reagents are all known to be potent inhibitors of prolyl endopeptidase. The major product after incubation of [3H]TRH in seminal plasma for 100 min was acid TRH (deamidated TRH) which is also the product after incubation of TRH with prolyl endopeptidase. Our results are consistent with the enzyme responsible for degradation of TRH and FPP in seminal plasma being similar to prolyl endopeptidase. The enzyme identified in this study is secreted and is therefore likely to be different from prolyl endopeptidase characterized from porcine brain, because the latter enzyme is known to be located in the cytosolic compartment of the cell.

Journal of Endocrinology (1995) 144, 61–66
Localisation of receptors for prolactin in ovine skin
Authors: Choy V J , Nixon A J , Pearson A J
Published: December 2008

Although prolactin (PRL) receptors are found in many mammalian tissues, specific PRL binding to mammalian skin has not been demonstrated. In view of the temporal relationships observed between photoperiod, circulating PRL and pelage replacement in seasonally responsive mammals, we sought to provide evidence of PRL receptors in ovine skin. Cryosections of skin from New Zealand Wiltshire ewes were incubated with radiolabelled human GH (125I-hGH) and ovine PRL (125I-oPRL) in the presence and absence of excess unlabelled hormones (hGH, oPRL or ovine GH (oGH)). Binding was inhibited by unlabelled oPRL and hGH but not by oGH. In microautoradiographs, both radioligands were localised most strongly in the dermal papillae of wool follicles in the anagen (growth) phase of the hair cycle and in apocrine sweat glands. Higher levels of specific binding to dermal papilla cells, compared with the follicle epithelial matrix and the surrounding dermis, were confirmed by measurement of microautoradiograph silver grain density (respectively, 34·±3·0, 11·4±1·0 and 5·5±0·5 grains per 100 μm2 (mean±s.e.m., n=10)). Total binding for 125IhGH and 125I-oPRL radioligands to follicle dermal papilla was not significantly different (34·1±3·0 vs 43·6±2·5 grains per 100 μm2, n=10) but the level of non-specific binding of 125I-oPRL was higher than for 125I-hGH (18·9±1·4 vs 6·1±0·6 grains per 100 μm2, n=10; (P<0·001). Binding assays of receptors in crude microsomal membranes extracted from ovine skin were used to ascertain binding capacity and specificity. Scatchard analysis yielded a dissociation constant (3·9 nm) and receptor concentration (2·22 pmol/mg protein) similar to that reported for ovine mammary gland. These results provide evidence for the presence of PRL receptors in ovine skin and are consistent with the hypothesis that PRL has a direct role in mediating wool follicle activity.

Journal of Endocrinology (1995) 144, 143–151
Effects of cyclosporine at the hypothalamic-pituitary axis in pituitary-grafted young female rats
Authors: Esquifino A I , Moreno M L , Arce A , Agrasal C , Pérez-Díaz J , Villanúa M A
Published: December 2008

This work was designed to investigate the effects of cyclosporine on prolactin secretion by an ectopically grafted heterologous pituitary gland, and on the hypothalamic content of norepinephrine, dopamine and serotonin. The administration of cyclosporine prevented the augmentation in plasma prolactin levels which occurred following an ectopic graft of a litter-mate pituitary gland. In contrast, in sham-operated rats, cyclosporine increased prolactin levels on day 8 of treatment. Both pituitary grafting and cyclosporine treatment in sham-operated rats decreased hypothalamic norepinephrine content. In grafted rats, cyclosporine returned hypothalamic norepinephrine to normal. Hypothalamic serotonin content decreased 8 days after pituitary grafting but increased to the values of control animals after cyclosporine administration. Cyclosporine treatment for 2 and 8 days increased serotonin content in sham-operated animals. As expected, the hypothalamic dihydroxyphenylacetic acid/dopamine index increased after pituitary grafting and administration of cyclosporine for 8 days resulted in a further increase. Cyclosporine administration for 2 days, however, decreased this index to the values observed in control animals while drug treatment of control rats for 8 days decreased the dihydroxyphenylacetic acid/dopamine index. In vitro release of prolactin from the ectopic gland was markedly decreased in animals treated with cyclosporine for 2 days and this effect was less evident in 8-day treated rats. These data suggest that the impairment of the local immune reaction after pituitary grafting, by cyclosporine administration for 2 days, prevents the augmentation of plasma prolactin levels and normalizes the hypothalamic catecholamine parameters, thus suggesting that the effects of cyclosporine at the hypothalamo-pituitary axis are exerted through changes in prolactin secretion by the graft, although chronic administration of cyclosporine may also have a direct effect on the hypothalamus.

Journal of Endocrinology (1995) 144, 159–164
Regulation of porcine skeletal muscle nuclear 3,5,3′-tri-iodothyronine receptor binding capacity by thyroid hormones: modification by energy balance
Authors: Morovat A , Dauncey M J
Published: December 2008

Thyroid hormones have been implicated in the regulation of nuclear 3,5,3′-tri-iodothyronine (T3) receptor binding capacity (Bmax) but, despite numerous in vivo and in vitro studies, there is considerable controversy regarding their exact role. Since changes in thyroid status alter energy balance and hence may influence T3 receptor numbers, the effects of chronic hypothyroidism and T4 treatment have been studied in young pigs under conditions of controlled energy intake. Four groups of animals comprising a hypothyroid, a euthyroid and a hyperthyroid group, all on the same level of food intake, and a hyperthyroid group on twice the amount of food were used. After 3 weeks on the treatment regimes, both the hypothyroid animals on the same level of food intake and the hyperthyroid animals on twice the amount of food had significandy increased Bmax values (97% and 137% higher respectively) compared with euthyroid controls. However, there was no difference between controls and the hyperthyroid animals on the same level of food intake. In a second study, the effects of short-term treatment of euthyroid animals with T3 was investigated. Results showed that in two groups of controls that received intravenous saline, those on a higher food intake had higher Bmax values (76% increase). Intravenous T3 administration to animals on a low food intake did not change the receptor numbers. In none of the studies was there any change in the dissociation constant of the receptors as a result of different treatments. It is suggested that, at least in postnatal life, thyroid hormones per se have no significant effect on nuclear T3 receptor numbers in skeletal muscle. Instead, changes in Bmax in response to thyroid status may be secondary to alterations in energy balance induced by these hormones.

Journal of Endocrinology (1995) 144, 233–242
111In-Octreotide and 99mTc(V)-dimercaptosuccinic acid studies in the imaging of recurrent medullary thyroid carcinoma
Authors: Berna L , Cabezas R , Mora J , Torres G , Estorch M , Carrió I
Published: December 2008

Detection of recurrence from medullary thyroid carcinoma (MTC) remains a diagnostic problem, especially when increased serum tumour marker levels suggest recurrence and conventional imaging techniques are non-diagnostic. In this study, we performed 111In-octreotide and 99mTc(V)-dimercaptosuccinic acid (DMSA) scans in a series of eleven patients with MTC presenting with elevated serum tumour markers after surgery.

111In-octreotide whole body studies detected tumour in six of the eleven patients studied and detected nine tumoral localizations. 99mTc(V)-DMSA whole body studies detected tumour in five of the eleven patients studied and eight tumoral localizations. 111In-octreotide and 99mTc(V)-DMSA studies detected recurrence in all four patients with basal calcitonin levels above 1000 ng/l. We conclude that 111In-octreotide and 99mTc(V)-DMSA studies have limited sensitivity to detect recurrence in patients with MTC, although their sensitivity may improve with high serum calcitonin levels. These radionuclide imaging techniques should be employed when conventional imaging techniques are negative or inconclusive or, in the case of 111In-octreotide studies, should be employed when we want to investigate the presence of somatostatin receptors that provide the basis for treatment with somatostatin analogues.

Journal of Endocrinology (1995) 144, 339–345
Effect of in vivo thyroid hormone status on insulin signalling and GLUT1 and GLUT4 glucose transport systems in rat adipocytes
Authors: Matthaei S , Trost B , Hamann A , Kausch C , Benecke H , Greten H , Höppner W , Klein H H
Published: December 2008

To examine the effect of thyroid hormone status on insulin action in isolated rat adipocytes, age- and weight-matched Sprague–Dawley rats were rendered hypothyroid (h) by i.p. injection of 2 mCi [131I]/kg. Another group of rats was made hyperthyroid (H) by i.p. injection of 500 μg l-thyroxine/kg/day for 7 days. The T4 levels in experimental groups were: controls, 33·5±0·95; h, 12·3±1·59: H, 133·2±8·8 μg/l. Adipocytes were isolated and 3-O-methylglucose transport (GT), insulin binding (IB) and insulin receptor kinase activity (IRKA) were determined. Subcellular membrane fractions (low-density microsomes, plasma membranes) were prepared and GLUT1 and GLUT4 glucose transporter immunodetected.

Hyperthyroidism caused no significant effect on either IB or IRKA but increased insulin-stimulated GT by 43·6%. This increase of GT was associated with an increase of primarily GLUT4 glucose transporters. Hypothyroidism was associated with both increased insulin receptor affinity and enhanced IRKA. Despite a marked reduction of primarily GLUT4 glucose transporters, basal and insulinstimulated GT was not reduced when compared with control.

These results suggest that (1) in hyperthyroidism, increased insulin-stimulated glucose transport is associated with an increase of primarily GLUT4 glucose transporters, which may be responsible for the increment of peripheral glucose utilization in hyperthyroidism, and (2) the effect of hypothyroidism on insulin action in adipocytes is characterized by a state of increased insulin sensitivity, as indicated by the increase in insulin receptor affinity and tyrosine kinase activity. Despite the marked reduction of primarily GLUT4 glucose transporters, insulin-stimulated glucose transport is not diminished, which may suggest that functional activity of plasma membrane glucose transporters is enhanced in hypothyroidism.

Journal of Endocrinology (1995) 144, 347–357
Endocrine control of the distribution of basic fibroblast growth factor, insulin-like growth factor-I and transforming growth factor-β1 mRNAs in adult rat adrenals using non-radioactive in situ hybridization
Authors: Ho M M , Vinson G P
Published: December 2008

This study located the particular cell types involved in the synthesis of growth factors in adult female rat adrenal glands. Non-isotopic in situ hybridization was used and the cellular localizations of the mRNAs of basic fibroblast growth factor (bFGF), IGF-I, and transforming growth factor-β1 (TGF-β1) were studied in adrenals from control animals and from those treated with ACTH or subjected to dietary sodium restriction. The adrenal medulla was the richest source of both bFGF and IGF-1 mRNA in both control and experimental rat adrenals. In the cortex, bFGF and IGF-I mRNAs were found mainly in the zona fasciculata in control animals, although some transcription was also detected in the zona reticularis and zona glomerulosa. Both ACTH and sodium restriction activated bFGF and IGF-I gene expression in the zona glomerulosa. Since cellular proliferation and differentiation occur primarily in the outer cortex, the data are consistent with the view that bFGF and IGF-I act as an autocrine/paracrine mitogen and differentiation regulator respectively in the rat adrenal cortex.

Very small amounts of TGF-β1 mRNA were detected, predominantly in the zona fasciculata of control rats. There were no observable differences in amounts and localization of TGF-β1 mRNA between the adrenals of control rats and those treated with ACTH for 1 day. TGF-β1 mRNA was very weak or undetectable in the adrenals from rats treated with ACTH for three and five days or from sodium-restricted rats. Although TGF-β1 immunoreactive protein has been shown to be present in the zonae fasciculata and reticularis and to modulate negatively the steroidogenic activities in the adrenal cortex of other species, its gene is not actively expressed in rat adrenals.

The present results showed that ACTH administration or dietary sodium restriction, both important adrenal mitogens in vivo, significantly altered the spatial patterns of the distribution of bFGF and IGF-I mRNAs and also increased the amount of bFGF mRNA in the adrenal cortex. This suggests that growth and differentiation of the adrenal cortex are partly mediated by bFGF and IGF-I.

Journal of Endocrinology (1995) 144, 379–387
Hypothalamic processing of β-endrophin in female C57BL/6J mice is altered at middle age
Authors: Joshi D , Bennett H P J , James S , Tousignant P , Miller M M
Published: December 2008

β-Endorphin (β-endo) (1–31) is the active opioid peptide product of pro-opiomelanocortin processing. Further post-translational modifications of β-endo(1–31) yield β-endo(1–27), (1–26) and their acetylated forms which are considered to be opiate receptor antagonists. Mechanistically, alteration in opiatergic properties is likely to result in the loss of a number of physiological functions including reproductive capacity. The purpose of this study was to determine whether there are changes in the way β-endo neurones process the peptide with age in female C57BL/6J mice. Pooled extracts of arcuate nucleus (ARC) and preoptic area (POA) of 3- to 4-month-old normally cycling (4–5 days at dioestrus), 12- to 13-month-old irregularly cycling (5–7 days at dioestrus), 23- to 24-month-old acyclic (in persistent dioestrus) animals were subjected to reversed-phase HPLC (n=4 experiments). Column fractions were assayed for β-endo-like-immunoreactivity by sequence-specific RIAs. The opiate receptor active as well as opiate receptor antagonist forms of β-endo were present in both ARC and POA at all three age groups although their ratios varied. β-Endo(1–31), the active opiate, was the predominant form in young animals. At middle age there was a threefold (P<0·05, ANOVA) increase in the antagonist forms of β-endo and this was associated with a significant (P<0·05, ANOVA) increase in the ratio of antagonist to active forms. This was accompanied by a trend toward an increase in acetylated forms of β-endo in middle-aged mice. HPLC profiles from hypothalami of old animals more closely resembled those of young females. The increase in the antagonist forms of β-endo at middle age may contribute to a decline of opiatergic influences in the female C57BL/6J mouse and suggest a mechanism whereby alterations in opiate influence over gonadotrophin control may occur.

Journal of Endocrinology (1995) 144, 405–415
Overexpression of human insulin-like growth factor-II in transgenic mice causes increased growth of the thymus
Authors: van Buul-Offers S C , de Haan K , Reijnen-Gresnigt M G , Meinsma D , Jansen M , Oei S L , Bonte E J , Sussenbach J S , Van den Brande J L
Published: December 2008

In order to determine the effects of IGF-II overexpression on growth of mice, transgenic mice were produced carrying one of three different H-2Kb human IGF-II minigenes in which different non-coding exons (exon 5, truncated exon 5 or exon 6) preceded the coding exons 7, 8 and 9. These were spaced by truncated introns and for proper polyadenylation an SV40 polyadenylation signal was incorporated. The highest levels of IGF-II minigene mRNA expression were found in lines containing the truncated exon 5 construct (II5′). Those containing exon 6 (II6) had less expression and 5 constructs (II5) gave only moderate levels of mRNA expression. In general mRNA expression was highest in thymus and spleen, low in liver and kidney and absent in the brain. In addition, one 115' line showed expression in the brain. Serum IGF-II levels at 8 weeks of age were increased 7- to 8-fold in homozygous transgenic lines with construct II5′ without brain expression and 2- to 3-fold in the one that showed expression in the brain; serum IGF-I levels were unchanged. Serum IGFs in the lines containing the constructs 115 and 116 were not different from those of the controls. In all cases body length and weight as well as the weight of several organs such as brain, liver, kidneys, heart and spleen when expressed as a function of age did not differ from controls. Only the thymus showed a significant increase in weight in the transgenics II5′.

Inbreeding of 2 lines containing construct 115' with pituitary deficient Snell dwarf mice did not influence body length or weight despite increased serum IGF-II levels. Again the thymus showed a marked increase in growth. The biological activity of the IGF-II peptide was further demonstrated by increased serum IGF-binding protein-3 in the transgenic dwarf mice, as shown by Western ligand blotting.

In summary, overexpression of IGF-II in transgenic normal and dwarf mice does not affect overall body growth, but causes increased growth of the thymus. This suggests a role for IGF-II in thymic development by paracrine/autocrine action.

Journal of Endocrinology (1995) 144, 491–502
In vitro 19-norandrogen synthesis by equine placenta requires the participation of aromatase
Authors: Moslemi S , Silberzahn P , Gaillard J-L
Published: December 2008

Explants of equine full-term placenta have been shown to synthesize 19-norandrogens from labelled androgens. Steroid metabolites were purified by silica-gel column chromatography then analysed and quantified by C18-reverse-phase HPLC coupled to a radioactive flow detector. 19-Norandrostenedione was subsequently recrystallized to constant specific activity, providing unequivocal evidence of its synthesis by the equine placenta. 19-Norandrostenedione synthesis appeared to be localized in the microsomal fraction. Regardless of the substrate used, formation of 19-norandrogens was far weaker than that of oestrogens; moreover, the yield of 17-oxosteroids produced was much greater than that of 17β-hydroxysteroids, suggesting the presence of a dehydrogenase with predominant oxidative activity. Sulphoconjugated steroids formed were less than 0·5% of total steroids. Although 19-nortestosterone could not be generated by equine purified aromatase incubated with labelled testosterone, the synthesis of 19-norandrogens and oestrogens by equine placental explants was blocked by two specific aromatase inhibitors, 4-hydroxyandrostenedione and fadrozole.

Our results provide evidence for a placental origin of at least a part of the 19-norandrogens previously identified in the blood of the pregnant mare. Furthermore, it is suggested that 19-norandrogen biosynthesis would involve the enzymatic metabolism of 19-oxygenated androgens formed by equine aromatase.

Journal of Endocrinology (1995) 144, 517–525