bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of specific insulin-like growth factor (IGF)-I and IGF-II receptors on cultured rabbit articular chondrocyte membranes
Authors: Jansen J. , van Buul-Offers S. C. , Hoogerbrugge C. M. , de Poorter T. L. , Corvol M. T. , Van den Brande J. L. 
Published: December 2008

ABSTRACT
The interaction of insulin-like growth factor (IGF)-I and IGF-II with specific type-I and -II receptor sites on rabbit articular chondrocyte membranes was studied. With labelled IGF-I as tracer, half-maximal displacement of the label was obtained with 1·4 ng IGF-I/ml and 22 ng IGF-II/ml. Using IGF-II as labelled peptide, 16 ng unlabelled IGF-II/ml and 200 ng IGF-I/ml were needed to inhibit the binding by 50%. Covalent cross-linking experiments revealed the presence of typical type-I (Mr 130 000 under reducing conditions) and type-II (Mr 260 000) receptor sites. In addition, with 125I-labelled IGF-II a very intense labelled band appeared at Mr > 300 000. This band was not found in mouse liver membranes and human placental membranes.
Journal of Endocrinology (1989) 120, 245–249
Effects of neonatal androgenization on growth and carcass composition in female mice
Authors: Ventanas J. , López-Bote C. J. , García C. , Gázquez A. , Burgos J. 
Published: December 2008

ABSTRACT
Sixty female mice were injected neonatally with testosterone propionate. This led to an increase in body weight at 56 days (P<0.01) and a reduction in carcass fat (P<0.005). Food conversion ratio from 28 to 49 days was lower in the treated group than in the controls (P<0.01). The data indicate that treated females can reach values similar to those of males.
Histological studies revealed a lack of luteal tissue in treated females at 56 days. This effect might be due to a modification in the nervous control of ovarian activity. Growth hormone secretion was higher in treated females than in controls (P<0-05). These results suggest that androgenization of females to achieve the performance characteristics of intact males could have important implications in meat production.
Journal of Endocrinology (1989) 120, 281–285
Changes in the plasma concentrations of inhibin throughout the normal sheep oestrous cycle and after the infusion of FSH
Authors: McNeilly A. S. , Swanston I. A. , Crow W. , Tsonis C. G. , Baird D. T. 
Published: December 2008

ABSTRACT
A radioimmunoassay for inhibin was developed using a peptide containing the 1–26 amino acid sequence of the N-terminus of the α-chain of 32 kDa porcine inhibin as immunogen, and 125I-labelled tracer. Evaluation of this assay using Sephadex column chromatography, chromatoelectrophoresis and immunoblotting confirmed that it measured all forms of inhibin present in sheep follicular fluid and was suitable for measurement of inhibin in sheep plasma. There was no evidence of the presence of free α-subunit in either sheep follicular fluid or ovarian vein plasma.
The concentration of inhibin in jugular plasma throughout the follicular and luteal phases of four ewes with ovarian autotransplants was measured. The ovarian secretion of inhibin and oestradiol were also measured simultaneously throughout the follicular phase in a spontaneous cycle and after infusion of NIH-oFSH-S14 at 10 μg/h for 48 h following premature luteal regression induced by prostaglandin. The results showed: (1) no change in the peripheral concentration of inhibin throughout the cycle except an increase related to the periovulatory increase in FSH and LH. (2) Following luteal regression, the concentration of FSH fell as the secretion rate of oestradiol increased. During this time there was no significant change in the peripheral concentration of inhibin or ovarian inhibin secretion rate. (3) Following the infusion of FSH there was a marked increase in the concentration of inhibin in both ovarian and peripheral plasma and an increase in ovarian inhibin secretion rate. (4) The calculated metabolic clearance rate of inhibin, 20·3 ml/min, is similar to that of FSH.
We conclude that in the ewe the ovarian inhibin secretion rate is stimulated by FSH and, although inhibin may modulate the basal secretion of FSH, a change in its secretion does not account for the fall in FSH which occurs during the follicular phase of the sheep oestrous cycle.
Journal of Endocrinology (1989) 120, 295–305
Human 'pregnancy-associated endometrial α1-globulin', an insulin-like growth factor-binding protein: immunohistological localization in the decidua and placenta during pregnancy employing monoclonal antibodies
Authors: Waites G. T. , James R. F. L. , Bell S. C. 
Published: December 2008

ABSTRACT
We have previously shown that pregnancy-associated endometrial α1-globulin, a small molecular weight insulin-like growth factor-binding protein (IGF-BP), is quantitatively the major secretory protein product of the decidualized endometrium during human pregnancy. In the present study, employing monoclonal antibodies raised against this protein in an immunohistological technique, the cellular localization of the protein has been examined in the decidua and placenta during pregnancy. During the first trimester the protein was principally associated with the decidual cell in the decidualized decidua compacta region of the endometrium with both cytoplasmic and extracellular matrix-associated staining patterns being detected. No extensive staining was observed in the placenta. At term the protein was localized in similar cells in the placental bed and endometrium associated with the amniochorion but not in the placenta. These studies suggest that the decidual cell represents the major source of IGF-BP during pregnancy and have relevance to the origin of amniotic fluid IGF-BP and the paracrine role of the decidual cell in the control of trophoblast growth.
Journal of Endocrinology (1989) 120, 351–357
An enzyme-linked immunosorbent assay to study human relaxin in human pregnancy and in pregnant rhesus monkeys
Authors: Lucas C. , Bald L. N. , Martin M. C. , Jaffe R. B. , Drolet D. W. , Mora-Worms M. , Bennett G. , Chen A. B. , Johnston P. D. 
Published: December 2008

ABSTRACT
A sensitive and specific double-antibody enzyme-linked immunoassay, using a synthetic analogue of human relaxin for standard and immunogen, was developed for the measurement of human relaxin (hRLX) in serum and plasma. No cross-reactivity was observed for human insulin, human insulin-like growth factor-I, hGH, human chorionic gonadotropin, hFSH, hLH or human prolactin. The assay was used to monitor RLX concentrations in samples from men, non-pregnant and pregnant women, and in pregnant rhesus monkeys infused with hRLX. RLX was not detected in serum from men nor from non-pregnant women, while a concentration of 600 ng/l was measured in pooled sera from two pregnant women (pregnancies achieved by in-vitro fertilization). Immunoreactive RLX (1·1 μg/g) was found in human corpora lutea taken from ectopic pregnancies at 7 weeks. In an experiment with a pregnant rhesus monkey infused with human RLX analogue, less than 1·5% of the maternal concentration was measured in the fetal circulation. Even though preliminary, these data suggest a low level of transfer of human analogue relaxin across the placenta in a rhesus monkey. Further studies of the physiology of RLX in human pregnancy will be facilitated by the availability of this immunoassay.
Journal of Endocrinology (1989) 120, 449–457
Rate of reproductive involution following either exposure to short days or daily administration of melatonin is faster in inbred than in random-bred female Syrian hamsters
Authors: Reiter R. J. , Sabry I. , Nordio M. , Vaughan M. K. , Migliaccio S. 
Published: December 2008

ABSTRACT
The onset of cessation of oestrous cyclicity and associated organ and hormonal changes were compared in random-bred (RB) and inbred (IB) female Syrian hamsters kept either under short days (8 h light:16 h darkness; 8L:16D) or long days (14L:10D) and given daily afternoon injections of 25 μg melatonin. In response to short-day treatment, 100% of the IB hamsters exhibited vaginal acyclicity within 35 days; by comparison, none of the RB animals were acyclic at this time. The IB hamsters also exhibited other changes associated with exposure to short days, including increased body weight, enlarged ovaries, regressed uteri, elevated pituitary concentrations of FSH, and depressed pituitary and plasma concentrations of prolactin. At this time, only the pituitary FSH levels were increased in the RB animals kept under the same short-day conditions.
In a second experiment, RB and IB female Syrian hamsters were maintained under long days (14L:10D) and the rate of reproductive regression in response to daily afternoon injections of melatonin was compared. After 8 weeks of melatonin injections, 80% of the IB females were anoestrous, while all RB hamsters were still exhibiting 4-day oestrous cycles. Other changes associated with melatonin administration in the IB females included a marked drop in uterine weight and a depression in pituitary and plasma prolactin levels. The RB hamsters, although they were all still cyclic after 8 weeks, had increased body and ovarian weights, increased pituitary concentrations of FSH, and lower pituitary and plasma prolactin levels.
The results show that the IB strain of Syrian hamster, compared with the RB strain, responded more quickly with vaginal acyclicity to both exposure to short days and daily injections of melatonin. On the other hand, the IB hamsters responded more slowly in terms of oestrous acyclicity to melatonin injections than to treatment with short photoperiod.
Journal of Endocrinology (1989) 120, 489–496
Inhibitory effects of corticotrophin-releasing factor and β-endorphin on LH and FSH secretion in the lactating rat
Authors: Taya K. , Sasamoto S. 
Published: December 2008

ABSTRACT
The roles of corticotrophin-releasing factor (CRF) and β-endorphin in the suppression of LH and FSH secretion during lactation were investigated using ovariectomized lactating rats separated from their litters overnight. Within 1 h of returning the pups to their mothers a marked fall in plasma LH concentration and a large increase in plasma prolactin were noted. However, resuckling caused no significant change in plasma concentration of FSH until 12 h after the return of the litter but a significant decline occurred thereafter. Twenty-four hours after removal of the litter, a single i.v. injection of 200 μl anti-LHRH serum caused similar changes in plasma concentrations of LH and FSH observed in nursing rats during suckling. These results suggest that the suckling stimulus itself is responsible for the suppression of LH as well as FSH, via inhibition of the secretion of LHRH. Twenty-four hours after removal of the litter, a single intracerebroventricular (i.c.v.) injection of either 10 μg CRF or β-endorphin resulted in a rapid decrease in plasma LH. Only β-endorphin caused a marked increase in plasma levels of prolactin within 1 h whereas FSH was less affected by either hormone. Repeated i.c.v. administration of 10 μg CRF or β-endorphin at 6-h intervals caused a prolonged inhibition of LH as well as FSH secretion during 48 h, with β-endorphin being less effective than CRF.
These results demonstrate that the suckling stimulus alone suppressed the secretion of both LH and FSH, and suggest that this effect may be mediated by the inhibition of LHRH secretion from the hypothalamus. They also suggest that the suckling-induced inhibition of LHRH may be primarily mediated by endogenous CRF and opioid peptides.
Journal of Endocrinology (1989) 120, 509–515
POTENTIATION OF GROWTH HORMONE ACTIVITY IN SHEEP USING MCNCCLCNAL ANTIBODIES
Authors: Pell J.M. , Johnsson I.D. , Pullar R.A. , Morrell D.J. , Hart I.C. , Holder A.T. , Aston R. 
Published: December 2008

ABSTRACT
Monoclonal antibody CAll was raised against ovine GH; its effects on GH activity were examined in a target species relevant for animal production in vivo. The monoclonal antibody was found to enhance the galactopoietic response to exogenous GH in adult lactating ewes and also to potentiate the diabetogenic activity of both exogenous and endogenous GH in ewe lambs. Thus it was shown that GH activity may be manipulated above its usual dose-response range in normal, intact animals of commercial importance via immunological means.
In-vivo uptake of human growth hormone in male rat liver
Authors: Bullier-Picard F. , Postel-Vinay M. C. , Kayser C. 
Published: December 2008

ABSTRACT
125I-Labelled human GH (hGH) was injected i.v. to male rats and its subcellular distribution in the hepatocyte was examined using fractionation techniques. Uptake into liver homogenates was maximal by 15 min after injection and represented 24% of the injected radioactivity; it was markedly inhibited by coinjection of native hGH. 125I-Labelled hGH taken up by the liver underwent a time-dependent translocation process. The peak of specific labelling of plasma membranes occurred at 3 min whereas later on the radioactivity was concentrated in low-density structures present in Golgi-endosome fractions. To characterize the ligand-associated structures better, endosome-enriched fractions were prepared from a microsomal fraction by isopycnic centrifugation in a sucrose gradient and a Nycodenz gradient. The radioactivity was in one peak with a median density of 1·096 g/cm3 in the Nycodenz gradient fractions. The peak of radioactivity was distinct from that of galactosyltransferase activity which appeared at a median density of 1·114 g/cm3. The labelled material eluted from the various subcellular fractions appeared as intact hGH.
Upon in-vivo interaction with male rat hepatocytes, 125I-labelled hGH was internalized with a sequential association with plasma membranes and endocytic structures distinct from Golgi elements.
Journal of Endocrinology (1989) 121, 19–25
Effects of hypothyroidism, tri-iodothyronine and glucocorticoids on growth hormone responses to growth hormone-releasing hormone and His-d-Trp-Ala-Trp-d-Phe-Lys-NH2
Authors: Edwards C. A. , Dieguez C. , Scanlon M. F. 
Published: December 2008

ABSTRACT
The aim of this study was to investigate the role of thyroid hormones and glucocorticoids on GH secretion. Secretion of GH in response to GH-releasing hormone (GHRH) (5 μg/kg) was markedly (P < 0·001) decreased in hypothyroid rats in vivo (peak GH responses to GHRH, 635 ± 88 μg/l in euthyroid rats vs 46 ±15 μg/l in hypothyroid rats). Following treatment with tri-iodothyronine (T3; 20 μg/day s.c. daily for 2 weeks) or cortisol (100 pg/day s.c. for 2 weeks) or T3 plus cortisol, a marked (P <0·01) increase in GH responses to GHRH was observed in hypothyroid rats (peak GH responses, 326 ±29 μg/l after T3 vs 133+19 μg/l after cortisol vs 283 ± 35 μg/l after cortisol plus T3). In contrast, none of these treatments modified GH responses to GHRH in euthyroid animals. Hypothyroidism was also associated with impaired GH responses to the GH secretagogue, Hisd-Trp-Ala-Trp-d-Phe-Lys-NH2 (GHRP-6). Secretion of GH in response to GHRP-6 in vivo was reduced (P <0·01) in hypothyroid rats (peak GH responses, 508 ± 177 μg/l in euthyroid rats vs 203 ± 15 μg/l in hypothyroid rats). In-vitro studies carried out using monolayer cultures of rat anterior pituitary cells derived from euthyroid and hypothyroid rats showed a marked impairment of somatotroph responsiveness to both GHRP-6 and somatostatin in cultures derived from hypothyroid rats. In summary, our data suggest that thyroid hormones and glucocorticoids influence GH secretion by modulating somatotroph responsiveness to different GH secretagogues.
Journal of Endocrinology (1989) 121, 31–36
Characterization and localization of receptors for epidermal growth factor in ovine skin
Authors: Wynn P. C. , Maddocks I. G. , Moore G. P. M. , Panaretto B. A. , Djura P. , Ward W. G. , Fleck E. , Chapman R. E. 
Published: December 2008

ABSTRACT
Specific receptor sites for murine epidermal growth factor (EGF) have been characterized and their distribution determined in ovine skin. Binding of 125I-labelled EGF to skin membrane particles was temperature- and time-dependent, with equilibrium being reached within 1 h at 23 °C. Analysis of skin biopsies collected from ten castrated Merino sheep demonstrated the presence of a single class of saturable, high-affinity binding sites with a dissociation constant of 64 ± 4 (s.e.m.) pmol/l and a binding capacity of 33·8 ± 4·5 fmol/mg protein. Skin particle binding of 125I-labelled EGF was inhibited equipotently by mouse salivary gland EGF, EGF produced by recombinant DNA procedures and urogastrone. The EGF peptides 1–48, 6–53 and 7–53, derived from the native molecule by enzymatic cleavage, were much less potent. The relative binding potency of these molecules was correlated with their ability to induce precocious eyelid opening in mice and to inhibit wool follicle activity. Synthetic fragments representing the major structural domains of the EGF molecule (EGF(29–44), EGF(33–42) and EGF(3–31)) were inactive in both the receptor and bioassays. Auto-radiography of skin sections incubated with 125I-labelled EGF in vitro or of sections from skin which was perfused with 125I-labelled EGF in vivo demonstrated that EGF receptors were localized in undifferentiated cells of the epidermis and sebaceous glands, the inner and outer root sheath and bulb of wool follicles and in dermal arterioles. Differences in receptor concentration were observed between follicles following in-vivo perfusion of 125I-labelled EGF but not when the in-vitro labelling technique was used. The presence of receptors in these regions is consistent with the morphological changes in sheep skin in reponse to EGF administration which have been reported previously.
Journal of Endocrinology (1989) 121, 81–90
Concentrations of dopamine and noradrenaline in hypophysial portal blood in the sheep and the rat
Authors: Thomas G. B. , Cummins J. T. , Smythe G. A. , Gleeson R. M. , Dow R. C. , Fink G. , Clarke I. J. 
Published: December 2008

ABSTRACT
The concentrations of dopamine, noradrenaline and their respective primary neuronal metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylethyleneglycol (DHPG) were measured in the hypophysial portal and peripheral plasma of sheep and rats by combined gas chromatography–mass spectrometry. Hypophysial portal and jugular blood samples were taken at 5- to 10-min intervals for 3–7 h from six conscious ovariectomized ewes. Blood was also collected for 30 min under urethane anaesthesia from the cut pituitary stalk from 16 pro-oestrous female and five intact male rats.
In ovariectomized ewes, noradrenaline concentrations were higher in hypophysial portal plasma than in peripheral plasma (6·6 ± 0·8 vs 2·2 ± 0·4 nmol/l). In contrast, dopamine was undetectable (<1 nmol/l) in the portal and peripheral plasma of all ewes. Plasma levels of DOPAC and DHPG in portal and jugular samples were similar. In all pro-oestrous female rats, plasma concentrations of dopamine were higher in portal blood than in jugular blood (8·0±1·4 vs 4·8± 0·6 nmol/l). Detectable concentrations of dopamine were measured in the portal plasma of two out of five male rats. Noradrenaline concentrations were higher in portal plasma than in peripheral plasma of both female (8·3 ± 1·7 vs 3·7 ± 0·6 nmol/l) and male (14·8± 2·7 vs 6·1± 1·2 nmol/l) rats.
These data show that noradrenaline, but not dopamine, is secreted into the long portal vessels in sheep. The results suggest that there are species differences in the secretion of hypothalamic dopamine into hypophysial portal blood.
Journal of Endocrinology (1989) 121, 141–147
Effects of selective opioid-receptor blockade on the hypothalamo-pituitary-adrenocortical responses to surgical trauma in the rat
Authors: Cover P. O. , Buckingham J. C. 
Published: December 2008

ABSTRACT
Opioid substances have been shown to stimulate and depress the secretion of ACTH in the rat. Their opposing actions appear to be mediated in part by specific receptors in the hypothalamus which influence the secretion of corticotrophin-releasing factor (CRF). In an attempt to determine the physiological role of these receptor systems, experiments were carried out in which the plasma ACTH and serum corticosterone concentrations were determined before and after stress in rats treated s.c. with selective antagonists of μ-(naloxone, naltrexone), δ-(ICI 174864) and κ-(MR2266) opioid receptors. Neither naloxone (25–100 μg/100 g) nor naltrexone (50 μg/100 g) influenced the resting plasma ACTH or serum corticosterone concentrations. However, both inhibited (P < 0·01) the secretion of the two hormones elicited normally by surgical stress (laparotomy under ether anaesthesia). ICI 174864 (30–100 μg/100 g) also had little effect on resting hypothalamo-pituitary-adrenocortical (HPA) activity but, at the highest dose, it caused a small (P < 0·05) potentiation of the response to surgery. In contrast, MR2266 (150–300 μg/100 g) produced marked activation of the HPA system and not only stimulated the resting secretion of ACTH and corticosterone but also potentiated and prolonged the HPA response to stress.
The results suggest that μ- and κ-opioid receptors mediate opposing actions of endogenous opioid peptides, both of which may be physiologically important in the regulation of CRF release.
Journal of Endocrinology (1989) 121, 213–220
Cyclical changes in plasma renin during the oestrous cycle in the rat: synchronized effect of oestrogen and progesterone
Authors: De Vito E. , Guardia D. C. , Cabrera R. R. 
Published: December 2008

ABSTRACT
The aim of the present work was to study the relationship between sex hormones and plasma renin levels during the oestrous cycle in a Wistar-derived rat strain. Plasma renin activity (PRA) as well as plasma renin concentration (PRC) were increased during the day of oestrus in rats with controlled 4-day oestrous cycles. This increase in PRA and PRC was not found when rats were ovariectomized on dioestrus day 2 and samples measured on the expected day of oestrus. The increase in PRA and PRC was not found when normal cyclic rats were treated with either tamoxifen or the progesterone receptor blocker RU 38486. Treatment with progesterone at pro-oestrus after ovariectomy on dioestrus day 2 partially increased the PRA and PRC when compared with the values found during the day of oestrus in control rats. The combined treatment of ovariectomized rats on dioestrus day 2 with oestrogen and progesterone restored the normal increase in PRA and PRC values on the expected day of oestrus. We therefore postulate that the sodium diuresis promoted by progesterone may be modulated by the previous peak of oestrogen. However, stimulation of extrarenal sources of renin cannot be excluded nor can an involvement of inactive precursors of renin in the fluctuations of active renin that occur during the oestrous cycle. No important change in plasma renin substrate (PRC) was observed during the oestrous cycle. PRA, PRC and PRS were determined every 4 h during the 4-day oestrous cycle. Our results clearly show a rhythmic variation in PRA and PRC which increases during the day of oestrus with a peak at 06.00 h. No circadian variation related to the sleep-wakefulness rhythm or other regular daily changes in PRA, PRC or PRS was found.
Journal of Endocrinology (1989) 121, 261–267