bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for an interaction of insulin and sex steroids in the regulation of vitamin D metabolism in the rat
Authors: Nyomba B. L. , Bouillon R. , De Moor P. 
Published: December 2008

ABSTRACT
Vitamin D metabolites and vitamin D-binding protein (DBP) were measured in non-diabetic rats and in rats made diabetic with streptozotocin. The animals were studied in the intact state, after gonadectomy and during pregnancy. In male non-diabetic rats the serum concentrations of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and DBP decreased after orchidectomy and were restored by treatment with testosterone. In female non-diabetic rats, these parameters increased after ovariectomy. Increased 1,25-(OH)2D3 and decreased DBP concentrations were found during pregnancy in non-diabetic rats.
After the induction of diabetes in intact rats of both sexes, the concentration of DBP decreased, but a significant decrease in the concentration of 1,25-(OH)2D3 was found in male animals only. After ovariectomy, however, 1,25-(OH)2D3 decreased also in female diabetic rats.
Both orchidectomy and insulin deficiency depressed serum concentrations of 1,25-(OH)2D3 (−22 and −45% respectively) and DBP (−14 and −29% respectively), but the effects of insulin deficiency were greater than those of androgen withdrawal. Moreover, the testosterone concentration was twofold lower in intact male diabetic rats than in non-diabetic animals. Insulin, but not testosterone treatment, however, restored DBP and 1,25-(OH)2D3 concentrations in diabetic rats, and insulin was effective in intact as well as in gonadectomized animals.
This study shows that insulin deficiency decreases the concentrations of DBP and 1,25-(OH)2D3 in the rat, and that these decreases are facilitated by androgens, but counteracted by oestrogens.
J. Endocr. (1987) 115, 295–301
Sex differences in the LH responses to chicken LHRH-I and -II in the domestic fowl
Authors: Sharp P. J. , Dunn I. C. , Talbot R. T. 
Published: December 2008

ABSTRACT
Maximal incremental changes in plasma LH were compared in adult hens and cockerels after i.v. injection of chicken (c) LHRH-I (pGlu1-His2-Trp3-Ser4-Tyr5-Gly6-Leu7-Gln8-Pro9-Gly10-NH2) or cLHRH-II (pGlu1-His2-Trp3-Ser4-His5-Gly6-Trp7-Tyr8-Pro9-Gly10-NH2). The LH response to cLHRH-I and -II was more rapid and greater in cockerels than in hens. The potencies of the two decapeptides were the same in cockerels but different in hens. Relative to cLHRH-I, the potency of cLHRH-II was 0·91 (0·6– 1·2; 95% confidence limits) in cockerels and 36·5 (16·8–128·6) in hens.
The greater potency of cLHRH-II relative to cLHRH-I in the hen than in the cockerel could not be accounted for by sex differences in the half-lives of the decapeptides in the peripheral circulation. The half-lives of both decapeptides in hens and cockerels ranged between 2·42 and 3·77 min.
It is concluded that the interaction between LHRH-I and -II and the gonadotrophs is sexually differentiated in the domestic fowl.
A new homologous radioimmunoassay was established for cLH. As in other chicken LH radioimmunoassays, there was evidence of cross-reactivity with TSH.
J. Endocr. (1987) 115, 323–331
Nucleotide (cDNA) sequence encoding the horse gonadotrophin α-subunit
Authors: Stewart F. , Thomson J. A. , Leigh S. E. A. , Warwick J. M. 
Published: December 2008

ABSTRACT
Several cDNA clones corresponding to mRNA for the α-subunit of the horse (Equus caballus) pituitary and placental (chorionic) gonadotrophic hormones have been isolated and sequenced. Polyadenylated mRNA was purified from horse pituitary glands (the source of FSH and LH) and horse placental tissues (the source of chorionic gonadotrophin; CG). The mRNA preparations were characterized by in-vitro translation and Northern hybridization techniques using human and ovine gonadotrophin cDNA clones as probes. Complementary DNA libraries were created from the pituitary and placental mRNAs and a human CG α-subunit probe was used to isolate several horse α-subunit cDNA clones. The α-subunit nucleotide sequence from both sources of tissue was identical, thereby indicating that in the horse (as in man) the same gonadotrophin α-subunit gene is expressed in the pituitary and placenta. Our results are consistent with transcription of a single α-subunit gene for all the glycoprotein hormones in the horse, and we suggest that the reported differences between the horse CG and FSH α-subunit amino acid sequences determined by conventional peptide sequencing methods arose due to errors in the FSH α-subunit sequence. Comparison of the deduced amino acid sequence of the horse α-subunit with that of other α-subunit sequences indicated a number of significant differences which may be related to the unusual receptor-binding properties of the equine gonadotrophins.
J. Endocr. (1987) 115, 341–346
The subfornical organ and relaxin-induced inhibition of reflex milk ejection in lactating rats
Authors: Summerlee A. J. S. , O'Byrne K. T. , Jones S. A. , Eltringham L. 
Published: December 2008

ABSTRACT
Experiments were carried out on anaesthetized, lactating rats to investigate the possible role of the subfornical organ in mediating relaxin-induced inhibition of reflex milk ejection. Milk ejection was judged by the behavioural response of the sucklings and by transient rises in intramammary pressure. Radiofrequency lesions of the subfornical organ, or control lesions in adjacent areas of the cerebrum, did not affect the pattern or the magnitude of intramammary pressure changes at reflex milk ejection. Purified porcine relaxin given by either i.v. (5 μg) or intracerebroventricular (50 ng) injection suppressed reflex milk ejection in intact, sham-lesioned and control-lesioned rats, but had no effect on either the pattern or magnitude of reflex milk ejection in rats with lesions of the subfornical organ. The subfornical organ, which is situated at the interface between the blood, brain and the cerebrospinal fluid appears to mediate, at least in part, the relaxin-induced inhibition of reflex milk ejection in the rat.
J. Endocr. (1987) 115, 347–353
Effects of human prostatic mitogens on rat bone cells and fibroblasts
Authors: Koutsilieris M. , Rabbani S. A. , Goltzman D. 
Published: December 2008

ABSTRACT
We examined several characteristics of the mitogenic activity of extracts of human prostatic adenocarcinoma and human benign prostatic hyperplasia in fetal rat calvarial cells, cloned rat osteosarcoma cells and rat skin fibroblasts. Prostatic moieties produced maximal stimulation of [3H]thymidine incorporation at 24 h, were mitogenic in the absence or presence of various concentrations of serum, and were active in calvarial cells enriched with osteoblasts, skin fibroblasts and the cloned rat osteosarcoma cell line UMR 108. The known growth-promoting agents insulin, insulin-like growth factor, fibroblast growth factor, platelet-derived growth factor, epidermal growth factor, interleukin-1α and β and transforming growth factor β were also mitogenic in the indicator systems employed; however, maximally stimulating effects of these peptides in cells of the osteoblast phenotype were further enhanced with prostatic material. Prostatic activity was acid-stable and could be enriched with respect to osteoblast stimulation by hydrophobic and carboxymethyl ion-exchange chromatography. The results demonstrate the presence of potent mitogenic activity in hyperplastic and malignant prostatic tissue which appears to include unique osteoblast-stimulating activity.
J. Endocr. (1987) 115, 447–454
Hydroxyindole-O-methyltransferase catalyses production of methoxyindoles in rat pineal gland dependent on the concentration of hydroxy precursors and their affinity for the enzyme
Authors: Morton D. J. 
Published: December 2008

ABSTRACT
Indole metabolites were separated by thin-layer chromatography following organ culture of rat pineal glands with tritiated tryptophan. Methoxyindole production was shown to differ substantially from results obtained when pineal glands were incubated with radiolabelled serotonin. The correlation between hydroxy- and corresponding methoxyindoles was, however, remarkably similar to previous results, and indicated that in the pineal gland, it is probable that production of methoxyindoles is dependent on the concentration of the various hydroxyindoles and their relative affinities for hydroxyindole-O-methyltransferase. It is also probable that although several forms of the enzyme may exist in the pineal gland, the catalytic sites are homogeneous in their activity.
J. Endocr. (1987) 115, 455–458
Ca2+ ionophore A23187-induced rise in cytoplasmic free calcium and iodide discharge in porcine thyroid cells: measurement of cytoplasmic free calcium by aequorin
Authors: Takasu N. , Murakami M. , Nagasawa Y. , Yamada T. , Shimizu Y. , Kojima I. , Ogata E. 
Published: December 2008

ABSTRACT
The cytoplasmic concentration of free calcium was measured using aequorin, a calcium-sensitive photoprotein. The Ca2+ ionophore A23187 induced a rise in cytoplasmic free calcium and iodide discharge in cultured porcine thyroid cells. The minimum dose of A23187 effecting an increase in cytoplasmic free calcium induced iodide discharge. The A23187-induced rise in cytoplasmic free calcium was followed by iodide discharge. The results indicate that A23187-induced iodide discharge is mediated by a rise in the cytoplasmic concentration of free calcium.
J. Endocr. (1987) 115, 477–480
Effects of oestradiol-17β on testicular microcirculation in rats
Authors: Widmark A. , Damber J. E. , Bergh A. 
Published: December 2008

ABSTRACT
The effect of oestradiol-17β on testicular micro-circulation in intact and hypophysectomized rats was studied before and after treatment with human chorionic gonadotrophin (hCG). Treatment of intact rats with oestradiol-17β for 5 days did not influence vasomotion but decreased testicular interstitial fluid volume (IFV). Treatment of intact rats with 50 IU hCG 8 h before the experiment began induced an increase in testicular IFV, abolished vasomotion and increased the accumulation of polymorphonuclear leucocytes in the testicular venules and interstitium. These changes were unaffected by pretreatment with oestradiol-17β, despite the decreased testosterone production. However, pretreatment with oestradiol-17β potentiated the hCG-induced migration of polymorphonuclear leucocytes to the interstitium. The interstitial fluid volume and number of polymor phonuclear leucocytes in blood vessels were decreased in hypophysectomized rats, and vasomotion was abolished. Daily treatment with 5 IU hCG increased the IFV and the number of polymorphonuclear leucocytes in blood vessels, and preserved vasomotion. Treatment of hypophysectomized rats with oestradiol-17β decreased testosterone production but did not influence basal IFV, vasomotion or the changes in IFV and vasomotion induced by 5 IU hCG. The present study shows that the regulation of testicular vascular permeability and vasomotion may not be directly related to testicular steroidogenesis, and that oestrogens are probably not involved as a mediator of the hCG-induced changes in testicular microcirculation.
J. Endocr. (1987) 115, 489–495
Effects of ACTH and ACTH fragments on DNA synthesis in guinea-pig adrenal segments kept in organ culture
Authors: Wulffraat N. M. , Drexhage H. A. , Jeucken P. , van der Gaag R. D. , Wiersinga W. M. 
Published: December 2008

ABSTRACT
Stimulation of adrenal DNA synthesis by ACTH(1–39) and its fragments ACTH(1–24) (Synacthen) and ACTH(18–39) was investigated. Synthesis of DNA was measured as the increase in the percentage of cells in S-phase (Feulgen densitometry) in guinea-pig adrenal explants kept in organ culture and exposed to the peptides for 5 h at 37 °C. ACTH(1–39) and its C-terminal fragment ACTH(18–39) (corticotrophin-like intermediate lobe peptide) were found to be potent stimulators of in-vitro adrenal DNA synthesis. The dose–response kinetics were biphasic and optimal responsiveness was reached in both instances at 1 fmol/1–10 pmol/l (this biological effect of ACTH(18–39) has hitherto not been described). The N-terminal fragment ACTH(1–24) gave only minimal responses. Thyrotrophin and LH, tested as controls, did not induce adrenal DNA synthesis. Epidermal growth factor was a potent stimulator of adrenal DNA synthesis in vitro.
Our data suggest a trophic action of the C-terminal part (ACTH(18–39)) of the corticotrophic molecule. Clear trophic effects were also found for the N-terminal part of the pro-opiomelanocortin molecule N-POC(1–76) (optimum 0·1 nmol/l) and N-POC(51– 62) (optimum 0·1 pmol/l). The latter observations support earlier concepts that this part of the proopiomelanocortin molecule has a stimulatory effect on adrenal DNA synthesis.
J. Endocr. (1987) 115, 505–510
COLLAGEN AND NON–COLLAGEN PROTEIN TURNOVER IN SKELETAL MUSCLE OF GROWTH HORMONE–TREATED LAMBS
Authors: Pell J. M. , Bates P. C. 
Published: December 2008

ABSTRACT
Long–term administration of GH to normal, well–fed lambs caused a significant increase in net muscle growth. This could be accounted for by increased rates of muscle protein synthesis, although red and white muscles responded differently. The increased rate of protein synthesis was due to an increased protein synthetic capacity (increased muscle RNA content) but efficiency per unit of RNA also tended to increase in red muscle. For similar increases in net growth, protein turnover was increased to a much greater extent in red than in white muscle. The ratio of collagen to non–collagen protein was unaffected in both muscle types by GH treatment, even though collagen synthesis rates were significantly increased in red muscle. To date, GH is the only anabolic agent in ruminants which acts via increased rates of protein synthesis rather than by decreased rates of protein degradation.
ISOLATION, AMINO ACID SEQUENCE AND ACTION OF GUINEA-PIG ACTH ON ALDOSTERONE PRODUCTION BY GLOMERULOSA CELLS
Authors: Smith A.I. , Wallace C.A. , Moritz R.L. , Simpson R.J. , Schmauk-White L.B. , Woodcock E.A. , Funder J.W. 
Published: December 2008

ABSTRACT
Though minor sequence differences between-species have been reported for adrenocorticotrophin, ACTH(1–39), the steroidogenic moiety ACTH(1–24) has appeared invariant in mammals. We here report the isolation, purification and amino acid sequencing of guinea-pig (GP) ACTH in which Pro24 is replaced by [ill] Ala24, and the demonstration that GP-ACTH stimulates aldosterone production to maximal levels well above those seen with human ACTH(1–39) or Synacthen, ACTH(1–24) amide, the synthetic ACTH fragment widely used for diagnostic and therapeutic purposes.
Granulated metrial gland cells in the non-traumatized regions of the uterus of ovariectomized mice with deciduomata maintained on progesterone
Authors: Stewart I. 
Published: December 2008

ABSTRACT
A study has been made of granulated metrial gland (GMG) cells in the non-traumatized regions of the uterus of ovariectomized mice maintained on progesterone and with deciduomata in part of one uterine horn. GMG cells were found in the non-traumatized region of the uterine horns with deciduomata for at least 8 days after induction of the decidual reaction. GMG cells were not found in the contralateral horns without deciduomata. Activation of endometrial stromal cells is characterized by a high mitotic index and, in mice given colchicine, numerous stromal cells were arrested in metaphase in the non-traumatized region of the uterine horns with deciduomata for at least 3 days after induction of the deciduomata. In uterine horns without deciduomata, stromal metaphases were few in number over the same period. A correlation was therefore found between the presence of GMG cells and large numbers of stromal cells in mitosis. There was also a correlation between the absence of GMG cells and small numbers of stromal cells in mitosis. These results are compatible with the hypothesis that the differentiation and maintenance of GMG cells are under the control of endometrial stromal cells.
J. Endocr. (1988) 116, 11–15
Thyrotrophin and cyclic AMP regulation of thyroglobulin gene expression in cultured porcine thyroid cells
Authors: Chabaud O. , Chambard M. , Gaudry N. , Mauchamp J. 
Published: December 2008

ABSTRACT
The effects of thyrotrophin, cholera toxin and 8-chloro-cyclic AMP on thyroglobulin gene expression in cultured porcine thyroid cells were compared. Cells organized either into monolayers in culture chambers with porous bases or into inside-out follicles in suspension were used. Thyroglobulin mRNA content was measured by dot-blot hybridization, and thyroglobulin synthesis rate was determined by immunoprecipitation of [35S]thyroglobulin after 2 h labelling with [35S]methionine. Cholera toxin and 8-chlorocyclic AMP increased the thyroglobulin mRNA content and thyroglobulin synthesis rate in the same ratio (∼3) as did thyrotrophin, showing that cyclic AMP mediates the effect of thyrotrophin on thyroglobulin gene expression. The culture chamber system provides for contact of the effectors with either the apical or the basolateral membrane.
The addition of 0·02–0·1 mU thyrotrophin/ml on the basolateral side of the cell layer gave a maximal response whereas this response was not reached on the apical side even with the addition of 5 mU/ml. In contrast, cholera toxin and 8-chloro-cyclic AMP stimulated thyroid cells equally on both sides.
J. Endocr. (1988) 116, 25–33
Molecular forms of growth hormone in the chicken pituitary gland
Authors: Houston B. , Goddard C. 
Published: December 2008

ABSTRACT
Different forms of GH present in freshly prepared homogenates of chicken pituitary were analysed by high-performance gel permeation chromatography and by immunoblotting following sodium dodecylsulphate polyacrylamide gel electrophoresis, non-denaturing polyacrylamide gel electrophoresis and isoelectric focussing. Chicken GH was found to occur mainly in a monomeric form with a relative molecular mass of 23 500 together with small amounts of interchain disulphide-linked oligomers. No evidence was obtained for proteolytically modified forms of GH nor for a form analogous to the 20K variant of human GH. Isoelectric focussing resolved ten distinct charge variants of chicken GH with isoelectric points between 8·45 and 6·0. The predominant charge variant (pI = 7·85) was present in pituitaries of birds of both sexes at all ages examined (3–114 days) whereas the more acidic forms were not apparent until after day 13. These findings indicate that the chicken pituitary contains different forms of GH, some of which may be developmentally regulated.
J. Endocr. (1988) 116, 35–41
Reduced oxytocin response to osmotic stimulus and immobilization stress in lactating rats
Authors: Higuchi T. , Honda K. , Takano S. , Negoro H. 
Published: December 2008

ABSTRACT
The release of oxytocin in response to an osmotic stimulus and immobilization stress was compared in lactating rats 8–12 days after delivery and in non-lactating rats. Intravenous injection of hypertonic saline or immobilization stress induced an increase in blood oxytocin levels in both lactating and non-lactating rats, but the increment in the former was significantly lower than that in the latter. The lower responsiveness of oxytocin release to stress in lactating rats was not altered by ovariectomy 2 days after parturition. Oxytocin release induced by electrical stimulation of the anteroventral third ventricle (an osmoreceptive area), paraventricular nucleus and neurohypophysis was significantly lower, to a similar extent, in lactating rats compared with non-lactating rats. These findings indicate that the structural reorganization reported in the hypothalamo-neurohypophysial system may not function to facilitate release of oxytocin in response to stress and osmotic stimulus in lactating rats. The reduced responsiveness of the release of oxytocin is independent of the influence of ovarian hormones, and may be due to the low ability of the oxytocin neurone itself to release oxytocin, and/or due to the activated inhibitory influence on the oxytocin neurone in the lactating rat.
J. Endocr. (1988) 116, 225–230
Biophysical characteristics of oxytocin secretory granules isolated from ovine corpora lutea
Authors: Rice G. E. 
Published: December 2008

ABSTRACT
Luteal oxytocin-containing secretory granules have been isolated and characterized in terms of their physicochemical parameters. The isopynic sedimentation density (1·03 ±0·003 g/ml) and sedimentation coefficient (1670 S, 0·32 mol sucrose/l, 4 °C) of these granules have been estimated. Based upon these estimates, the average vesicle diameter (258 ± 17 nm) and vesicle weight (9·92 ±0·67 fg/vesicle) were calculated. The exchangeable water content (58·2%) of these granules was determined using density gradients prepared with deuterium oxide. Luteal oxytocin-containing granules displayed similar physicochemical characteristics to those reported for neurohypophysial peptide-containing granules, with the exception of particle size. Luteal granules were 1·3 times greater in diameter than neurohypophysial granules.
J. Endocr. (1988) 116, 267–272
Potentiation of lactation-induced oxytocin secretion by intracerebroventricular oxytocin in the conscious goat
Authors: Seckl J. R. , Lightman S. L. 
Published: December 2008

ABSTRACT
The release of oxytocin into the cerebrospinal fluid (CSF) and plasma of lactating goats was studied following implantation of cisternal and lateral ventricular cannulae. Hand milking was associated with a significant increase in plasma concentrations of oxytocin, but no change in plasma concentrations of vasopressin or CSF concentrations of oxytocin. Intracerebroventricular (i.c.v.) infusion of oxytocin itself (1 pmol/min for 60 min) had no effect on basal plasma levels of oxytocin. It did, however, markedly potentiate the milking-induced increase in plasma oxytocin above the levels achieved during i.c.v. infusion of artificial CSF alone. In the goat, therefore, milking results in a selective release of oxytocin into the plasma, and this release can be potentiated by the presence of increased concentrations of oxytocin in the CSF.
J. Endocr. (1988) 116, 273–277
Opioid peptides do not modulate atrial natriuretic peptide or aldosterone release under basal conditions in man
Authors: Borges F. , Anderson J. V. , Volta C. , Perry L. , Drury P. L. , Bloom S. R. , Besser G. M. , Grossman A. 
Published: December 2008

ABSTRACT
The effect of two analogues of [Met]-enkephalin, [d-Ala2,N-Phe4,Met(0)-ol5]-enkephalin and its guanyl derivative, on plasma concentrations of atrial natriuretic peptide (ANP) and serum aldosterone in six normal subjects was investigated. All subjects were given a 1 litre water load to inhibit vasopressin release. Both analogues, when injected i.v. at a dose of 100 μg, stimulated release of prolactin and GH and inhibited serum cortisol; there was no significant change in blood pressure, pulse rate or urine output. Neither plasma concentrations of ANP nor serum aldosterone levels changed significantly after injection of either analogue at a low or high dose. Naloxone, given i.v. as an 8 mg bolus, also failed to alter concentrations of either ANP or aldosterone, while it significantly stimulated the release of serum LH and cortisol. It was concluded that under basal conditions opiate receptors are unable to modulate plasma ANP or serum aldosterone concentrations.
J. Endocr. (1988) 116, 313–317