bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of growth hormone and an antiserum to rat growth hormone on serum IGF-I and muscle protein synthesis and accretion in the rat
Authors: Palmer R. M. , Flint D. J. , MacRae J. C. , Fairhurst F. E. , Bruce L. A. , Mackie S. C. , Lobley G. E. 
Published: December 2008

ABSTRACT
Rats were injected twice daily for up to 10 days with GH or with a polyclonal antiserum to rat GH, commencing at 21–22 days of age.
Administration of bovine or human GH (1 mg/day) improved whole body growth rates by 22% and 29% respectively. Plantaris muscle mass was also increased, by 7 and 14% respectively. Anti-GH injected twice daily resulted in a 7% decrease in body weight at 4 days and a 10% reduction by 10 days. Similar decreases were observed in the total protein content of plantaris and soleus muscles. The decrease in the fractional rate of protein synthesis was proportionately greater than the decline in protein content in plantaris muscle whereas in the soleus no change in the rate of protein synthesis was observed, suggesting that the effect on this muscle was due to an increase in the rate of protein degradation.
Serum total IGF-I was unchanged by treatment with either GH or anti-GH while the amount of hepatic IGF-I mRNA was also unaffected by anti-GH injection. These data are consistent with a direct effect of GH or an effect mediated by an autocrine/paracrine mechanism of action on muscle but do not support a role for serum total IGF-I as an endocrine mediator of GH action.
Journal of Endocrinology (1993) 139, 395–401
Regulation of metabolic water and protein compartments by insulin-like growth factor-I and testosterone in growth hormone-deficient lit/lit mice
Authors: Donahue L. R. , Watson G. , Beamer W. G. 
Published: December 2008

ABSTRACT
Insulin-like growth factor-I (IGF-I) and testosterone are major hormonal regulators of protein metabolism. We chose genetically GH-deficient little (lit/lit) mice to test whether these anabolic hormones act independently or in concert with each other to stimulate protein metabolism. Hormones were administered for 14 days at constant rates to 14-week-old lit/lit female mice, IGF-I was infused via mini-osmotic pumps at 30 μg/day and testosterone was administered using 30 mg pellets. Food consumption was measured during the experimental period, and at the end we measured: (a) serum IGF-I, IGF-I-binding proteins (IGFBPs) and blood urea nitrogen (BUN); (b) body and musculo-skeletal carcass weights; (c) musculo-skeletal carcass water, fat, protein and mineral; and (d) selected organ weights plus protein and DNA contents.
We found that both of these growth-stimulatory hormones, IGF-I and testosterone, alone and in combination, had anabolic effects on different metabolic compartments in specific target organs. The most unexpected finding in this study was that the IGF-I-induced increase in musculo-skeletal carcass weight arose solely from increased water, revealing the importance of this compartment as an early target of IGF-I action. Other effects caused specifically by IGF-I, but not testosterone, included increases in serum IGFBP-3, body weight and spleen weight. The specific effect of testosterone, but not IGF-I, was to increase serum IGFBP-2. Independent effects were induced by each hormone alone for kidney and spleen weight, kidney and spleen protein content and BUN. Synergistic effects of IGF-I plus testosterone were observed for the musculo-skeletal preparation, organ weights (liver, kidney, heart and adrenal), liver protein and kidney DNA content. Food consumption did not differ among experimental groups. We conclude that in nutritionally replete GH-deficient lit/lit female mice, IGF-I regulates both water and protein metabolism in an organ-specific manner, whereas the effect of testosterone in specific organs is limited to protein metabolism.
Journal of Endocrinology (1993) 139, 431–439
Effects of dietary recombinant human insulin-like growth factor-I on concentrations of hormones and growth factors in the blood of newborn calves
Authors: Baumrucker C R , Blum J W 
Published: December 2008

Abstract
Colostrum is rich in insulin-like growth factor-I (IGF-I) and IGF-II and the dietary effects of recombinant human IGF-I (rhIGF-I) on the newborn are of interest. The objective of this study was to examine the effects of dietary rhIGF-I upon selected hormones and growth factors in the blood. Calves were fed for the first 2 days of life with one of three experimental diets: (1) milk replacer plus isolated colostrum-derived globulin (MR−), (2) as (1) plus 98 μmol rhIGF-I/l (MR+) or (3) pooled cow colostrum. Thereafter, all animals received only milk replacer at 5% of body weight/feeding twice a day with only treatment 2 having the continued addition of 98 μmol rhIGF-I/l until completion of the experiment 7 days after birth. Radioimmunoassays for insulin, prolactin, IGF-I, IGF-II, GH, l-thyroxine, 3,5,3′-l-triiodothyroline and cortisol were conducted. With the exception of GH, all hormones and growth factors examined showed some form of dietary effect, but many were transient, changing only with the first feeding. Both insulin and prolactin concentrations exhibited a transient increase in blood at the first feeding, but insulin increased with the MR− treatment whereas prolactin increased with the MR+ treatment. Total IGF-I concentration in blood did not show any diet-induced changes for the first 4 days, but thereafter a rise in blood concentrations of IGF-I was observed. These data indirectly support the hypothesis that dietary IGF-I may be absorbed and causes transient systemic effects in the newborn calf.
Journal of Endocrinology (1994) 140, 15–21
Over-expression of oxytocin in the testes of a transgenic mouse model
Authors: Ang H-L , Ivell R , Walther N , Nicholson H , Ungefroren H , Millar M , Carter D , Murphy D 
Published: December 2008

Abstract
The bovine oxytocin gene has been expressed in the testes of two independent transgenic mouse lines. Hybridization and RNase protection analysis showed that the oxytocin transgene was transcribed from the normal functional promoter in the Sertoli cells of the seminiferous tubules in a developmentally regulated manner. Immunohistochemistry indicated that both oxytocin and neurophysin epitopes were expressed together in the Sertoli cells at stages I–V and X–XII of the cycle of the seminiferous epithelium. Furthermore, analysis with high- performance liquid chromatography showed that there was a tenfold increase in the amount of amidated oxytocin present in testicular extracts from the transgenic mice. However, there appeared to be no detectable effect of this overproduction of hormone on testicular morphology or fertility parameters. A significant decrease by 50% was detected only in the levels of intratesticular testosterone and dihydrotestosterone. The results point to a local paracrine role for oxytocin in the modulation of Leydig cell function.
Journal of Endocrinology (1994) 140, 53–62
Role of endogenous atrial natriuretic peptide in volume expansion diuresis and natriuresis of the Pekin duck
Authors: Gray D A 
Published: December 2008

Abstract
Polyclonal antibodies raised in a rabbit against avian atrial natriuretic peptide (ANP) were shown to reduce circulating endogenous ANP levels in Pekin ducks by more than 90%, and were subsequently used to investigate the role of this peptide in volume expansion diuresis and natriuresis. Conscious birds, undergoing a steady-state diuresis and natriuresis maintained by an i.v. infusion of hypotonic saline at a rate of 0·7 ml/min, responded to ANP antiserum (anti-ANP) with an immediate 30% reduction in urine flow rate and sodium excretion which lasted for about 30 min. Plasma arginine vasotocin levels were not changed by anti-ANP whereas circulating angiotensin II concentrations increased immediately following the administration of anti-ANP. Serum from non-immunized normal rabbits produced no changes in the renal and plasma parameters monitored.
The results show that the high circulating levels of endogenous ANP associated with volume expansion promote renal salt and fluid excretion and thus have a major physiological role in avian volume homeostasis.
Journal of Endocrinology (1994) 140, 85–90
Free α subunit of human chorionic gonadotrophin: molecular basis of immunologically and biologically active domains
Authors: Dirnhofer S , Lechner O , Madersbacher S , Klieber R , de Leeuw R , Wick G , Berger P 
Published: December 2008

Abstract
Immunochemical studies were undertaken to identify surface-orientated epitopes of the free α subunit of human chorionic gonadotrophin (hCG-α) at the amino acid sequence level. We investigated the molecular organization of these epitopes, resolved the immunological topography in terms of spatial arrangement of antigenic domains and related structures to functions such as subunit association or receptor binding. Overlapping synthetic peptides covering the entire amino acid sequence of hCG-α, an enzymatically digested hCG-α subunit, and a reduced and alkylated hCG-α preparation were assayed in a solid-phase one-site enzyme-linked immunoassay, and in a solution-phase competitive radioimmunoassay (RIA). The antigenic topography was mapped by monoclonal antibodies (MCAs) in two-site binding assays (sandwich RIA). On the surface of hCG-α, seven different epitopes (α1–α7), arranged in four spatially distinct domains, could be distinguished: A, α1,2,4; B, α3,5; C, α6; D, α7. The peptides spanning hCG-α(13–18), hCG-α(17–22) and hCG-α(33–42) appeared to contribute to the formation of epitopes α2, α4 and α6 respectively. Since epitope α6 is present only on the free non-assembled subunit of different species, we concluded that the region hCG-α(33–42), which is evolutionarily highly conserved, represents a subunit assembly site. All but one epitope (α7) are destroyed by reducing and alkylating hCG-α. In contrast, chymotryptic digestion of hCG-α, leading to release of the heptapeptide hCG-α(41–47), did not affect epitope expression, indicating that this sequence is not involved in the formation of antigenic determinants. Addressing the biological properties of hCG-α epitopes by radioreceptor assay revealed that the three hCG-α peptides corresponding to epitopes α2, α4 and α6 did not displace radiolabelled hCG from its receptor, whereas any of the MCAs directed against determinants (α1–α5), shared by hCG and hCG-α, totally inhibited binding. Consistent with this, the antibodies neutralized the biological activity of hCG in terms of testosterone production in a mouse Leydig cell in vitro bioassay. We therefore concluded that hormone antibody-binding sites differ from those of hormone receptor binding, revealing no essential congruence of immunologically and biologically active domains.
Journal of Endocrinology (1994) 140, 145–154
Participation of the superior ovarian nerve in the regulation of compensatory ovarian hypertrophy: the effects of its section performed on each day of the oestrous cycle
Authors: Chávez R , Domínguez R 
Published: December 2008

Abstract
The effects were analysed of section of the superior ovarian nerve on compensatory ovulation and ovarian hypertrophy, in adult rats with the left or right ovaries extirpated during the oestrous cycle and autopsied 6 or 20 days later. Rats with hemiovariectomy or hemiovariectomy plus denervation recovered their oestrous cyclicity between 2 and 3 days after surgery. Six days after hemiovariectomy 14 out of 17 rats ovulated on the expected day of oestrus. All the animals were hemiovariectomized on the day of pro-oestrus. The mean ± s.e.m. number of ova shed was similar to the group of animals with both ovaries (7·8 ± 1·2 vs 9·5 ± 0·2 Compensatory ovarian hypertrophy was observed in the right ovary when left hemiovariectomy was performed on day 2 of dioestrus or pro-oestrus; similar results were observed in the left ovary when the right one was extirpated at oestrus or pro-oestrus. Section of the right superior ovarian nerve in left-hemiovariectomized rats caused a reduction in ovulation rate and number of ova released. Compensatory ovarian hypertrophy was modified in the opposite way by unilateral section of the superior ovarian nerve to the in situ ovary depending on the day of the cycle when hemiovariectomy was performed. Twenty days after treatment, ovulation rate, compensatory ovulation and ovarian hypertrophy were similar in both left- or right-hemiovariectomized rats. Compensatory ovarian hypertrophy increased in all animals with section of the superior ovarian nerve, except when hemiovariectomy was carried out at oestrus or the left ovary was extirpated on day 1 of dioestrus. The results suggest that modulation of compensatory ovarian hypertrophy by neural information arriving at the ovary by way of the superior ovarian nerve varies during the oestrous cycle.
Journal of Endocrinology (1994) 140, 197–201
Stimulatory effect of interleukin-1β on the hypothalamic-pituitary-adrenal axis of the rat: influence of age, gender and circulating sex steroids
Authors: Rivier C 
Published: December 2008

Abstract
The bilateral communication between the immune and neuroendocrine systems plays an essential role in modulating the adequate response of the hypothalamic-pituitary-adrenal (HPA) axis to the stimulatory influence of interleukins (ILs). It is thus reasonable to assume that inappropriate responses of the HPA axis to ILs might play a role in modulating the onset of pathological conditions such as infections. As part of our programme aimed at investigating the ability of ILs to release pro-opiomelanocortin-like peptides and corticosterone in rats exposed to alcohol, we observed that this stimulatory action appeared to be influenced by the gender of the animals. We therefore examined the ability of IL-1β, injected peripherally, to stimulate the HPA axis as a function of stage of sexual maturation and the presence or absence of circulating sex steroids.
In immature (21 to 22-day-old) rats, both males and females responded to the i.p. administration of 0·5 or 2·0 μg IL-1β/kg with statistically comparable increases in plasma ACTH levels. In contrast, females released significantly (P<0·01) more corticosterone in response to the lower dose of cytokine. Forty-day-old intact animals showed no sexual dimorphism in ACTH secretion, but the females again secreted significantly (P<0·05–0·01) more corticosterone. Gonadectomy, performed 7–8 days prior to the assay, increased the absolute amount of corticosterone released over a 60-min period. A noticeable dimorphism of the ACTH response to IL-1β became apparent in 70-day-old intact rats, with females secreting more ACTH than males. These females also released significantly more corticosterone than males under both resting and stimulated circumstances. In this age group, gonadectomy abolished the sex difference in terms of ACTH release, but augmented the total amount of corticosteroids secreted by both sexes, as well as increasing the sexual dimorphism.
These results suggest the presence of gender differences in the response of the HPA axis to IL-1β. While the sexual dimorphism of ACTH secretion appears to be dependent on circulating sex steroids, the sexually dimorphic adrenal response was retained following gonadectomy.
Journal of Endocrinology (1994) 140, 365–372
Effects of endothelin-1 and endothelin-3 on rat hypothalamic corticotrophin-releasing hormone and pituitary ACTH release in vitro
Authors: Calogero A E , Raiti F , Nicolosi G , Burrello N , D'Agata R , Mantero F 
Published: December 2008

Abstract
Endothelins (ETs) are potent vasoconstrictor peptides that also participate in the regulation of endocrine function. Indeed, immunoreactive ET, ET mRNA and ET receptors have been found in the brain and the pituitary gland and ETs stimulate arginine vasopressin, LH, FSH, TSH and gonadotrophin-releasing hormone and inhibit prolactin release in vitro. The present study was undertaken to evaluate the effects of ET-1 and ET-3, two members of this family, on corticotrophin-releasing hormone (CRH) release by explanted male rat hypothalami in vitro and on ACTH release by primary pituitary cell culture. ET-3 decreased basal CRH release in a concentration-related manner. The lowest effective concentration tested was 3 nmol/l but a more pronounced inhibitory effect was obtained at a concentration of 10 nmol/l. On the other hand, ET-1 did not have any detectable effect on basal CRH release. Neither ET-1 nor ET-3 had any effect on the release of CRH stimulated by potassium chloride. ET-1 increased basal ACTH release, whereas ET-3 did not have any effect. Both ET-1 and ET-3 suppressed the release of ACTH stimulated by 1 nmol CRH/l.
These data suggest that both ET-1 and ET-3 are able to modulate the hypothalamic-pituitary-adrenal axis function in vitro. However, they act at different levels and seem to have opposite effects. Indeed, while ET-1 stimulated pituitary ACTH release, ET-3, the peptide produced mainly in the brain, inhibited hypothalamic CRH release in vitro.
Journal of Endocrinology (1994) 140, 419–424
Low-dose cortisol infusion increases plasma corticosteroid-binding globulin (CBG) and the amount of hepatic CBG mRNA in fetal sheep on day 100 of gestation
Authors: Berdusco E T M , Milne W K , Challis J R G 
Published: December 2008

Abstract
Synthetic glucocorticoids stimulate the production of corticosteroid-binding globulin (CBG) by the liver of the sheep fetus near term (day 145). We have examined whether physiological changes in plasma cortisol alter plasma CBG concentrations, patterns of glycosylation and the amount of hepatic CBG mRNA at earlier times during pregnancy (day 100), prior to the activation of fetal hypothalamic-pituitary-adrenal function. Cortisol was infused into chronically catheterized sheep fetuses in amounts that raised the plasma cortisol concentration by about 15 nmol/l. This treatment resulted in a significant increase in the plasma corticosteroid-binding capacity and in the amount of CBG mRNA in the fetal liver, but did not alter the proportion of CBG retained using Concanavalin A chromatography. We conclude that the CBG gene in the liver of fetal sheep responds to physiological changes in plasma concentration of cortisol and we speculate that the rise in plasma CBG concentration is important in diminishing the negative feedback effect of circulating cortisol on the fetal pituitary and hypothalamus.
Journal of Endocrinology (1994) 140, 425–430
Secretory characteristics and phenotypic plasticity of growth hormone- and prolactin-producing cell lines
Authors: Kineman R D , Frawley L S 
Published: December 2008

Abstract
Considerable information regarding the regulation of GH and prolactin (PRL) release has been generated using pituitary cell lines as model systems. Inasmuch as these cultures have been derived from single cells by clonal selection it has frequently been assumed that they are composed of homogeneous populations of hormone secretors. However, experience with GH3 cells clearly demonstrates that such is not the case, since this GH- and PRL-producing line is comprised of a mixture of cells that are bihormonal, secrete only GH, or secrete neither hormone. Interestingly, the relative amount of these phenotypic subpopulations is not fixed, but can be altered by treatment with established regulators of GH and PRL secretion. This potential for secretory heterogeneity and phenotypic plasticity prompted us to examine the cellular composition of other commonly used GH- and/or PRL-secreting cell lines under control and treatment conditions. First, GH4C1, GH1, GC, MMQ and P0 cells were maintained according to established media and culture protocols and the relative abundance of GH and PRL secretors was assessed by reverse haemolytic plaque assays. As shown previously for GH3 cells, two cell lines were found to be functionally heterogeneous. Specifically, GH4C1 and GH1 were comprised of mixed populations of GH (25·9±1·1% and 51·3±6·5% (s.e.m.) respectively) and PRL (44·8±3·7 and 66·1 ±4·1% respectively) secretors. However, MMQ and GC cell cultures were relatively homogeneous with respect to hormone secretion in that the MMQ cells released PRL (72·2 ± 4·9%) but not GH, while GC cells released GH (93·6 ±1·4%) but not PRL. Similarly, P0 cell cultures contained predominantly GH-secreting cells (96·4±1·2%), but a few cells were detected that released PRL (1·1 ±0·1%). We then tested whether cortisol or oestradiol-17β (OE2) could alter the secretory composition of cell lines identified as reasonably homogeneous (GC, MMQ and P0) by treating cultures with steroids at doses ranging from 0·001 to 1000 nmol/l for up to 144 h. The presence of steroids in GC and MMQ lines did not affect the percentage of GH and PRL secretors. However, treatment of P0 cells with 0·001 to 1000 nmol OE2/l for 24, 48 and 144 h resulted in a dramatic increase in PRL cells when compared with controls. These increases occurred without alterations in GH percentages and in the absence of significant cell proliferation. In fact, OE2 suppressed the proliferation of P0 cells to 20% of the control rate (P<0·05), suggesting that OE2 induced pre-existing GH-secreting cells to release both GH and PRL. Taken together, these results clearly indicate that clonal origin does not guarantee homogeneity of function, and alteration in the culture environment can have profound effects on the secretory cell composition of acidophilic cell lines. These considerations have important implications for the interpretation of results generated with GH- and/or PRL-secreting cell lines.
Journal of Endocrinology (1994) 140, 455–463
Eel ventricular natriuretic peptide: isolation of a low molecular size form and characterization of plasma form by homologous radioimmunoassay
Authors: Takei Y , Takahashi A , Watanabe T X , Nakajima K , Ando K 
Published: December 2008

Abstract
Ventricular natriuretic peptide (VNP) with 25 amino acid residues was isolated from the low molecular weight fraction of acid extracts of eel cardiac ventricles. No other short forms of VNP were recovered from the fraction. This peptide was named eel VNP(1–25) because it was a C-terminally truncated form of the previously isolated eel VNP(1–36) As observed before with eel VNP(1–36), eel VNP(1–25) had a much higher (146-fold) vasodepressor activity than human atrial natriuretic peptide (ANP) in eels, but was a third to a half as active in rats with respect to vasodepressor and natriuretic activities. Eel VNP(1–25) was generally less potent than eel VNP(1–36) for vasodepressor and natriuretic effects.
A specific radioimmunoassay (RIA) has been developed for the measurement of eel VNP. The antiserum, raised against eel VNP(1–36), was highly specific and did not exhibit significant cross-reactivity with eel ANP and C-type natriuretic peptide, even though their amino acid sequences have more than 60% homology with that of eel VNP. The sensitivity of assay was 0·5 fmol/tube for eel VNP(1–36) with more than 99% confidence. Such high sensitivity permitted direct assaying of VNP with only a few microlitres of plasma.
In fresh water eels, the concentration of VNP in the cardiac ventricle was higher than those in the atrium or brain and that of ANP in the ventricle. Thus, VNP seems to be a ventricular hormone. Although ANP is a major circulating hormone in mammals, the plasma concentration of VNP was threefold higher than that of ANP. The RIA coupled with gel-permeation chromatography revealed that a 14 kDa form, probably proVNP, and smaller forms (3–6 kDa) circulate in eel plasma. Reversephase high performance liquid chromatography identified both VNP(1–36) and VNP(1–25) in eel plasma; VNP(1–36) appeared to be a major form.
Journal of Endocrinology (1994) 141, 81–89