bluuebunny/crossref_metadata_2025_split huggingface dataset:
Homologous and heterologous regulation of somatostatin-binding sites on chicken adenohypophysial membranes
Authors: Harvey S. , Baidwan J. S. , Attardo D. 
Published: December 2008

ABSTRACT
Binding of 125I-labelled [Tyr1]-somatostatin (125I-[Tyr1]-SRIF) to pituitary caudal lobe membranes was suppressed in immature chickens 1 and 2 h after i.v. administration of unlabelled SRIF at concentrations of 1–100 μg/kg. In-vitro preincubation of chicken pituitary glands for 0·5–4·0 h with 0·1 μmol SRIF/l similarly reduced the binding of 125I-[Tyr1]-SRIF to caudal lobe membrane preparations. After a 4-h incubation in 0·1 mmol SRIF/l, the withdrawal of SRIF from the incubation media was accompanied 4 h later by a partial recovery in the binding of 125I-[Tyr1]-SRIF to pituitary membranes. Passive immunoneutralization of endogenous SRIF resulted in a prompt (within 1 h) and sustained (for at least 24 h) suppression of 125I-[Tyr1]-SRIF binding to pituitary membranes. The i.m. administration of cysteamine (300 mg/kg) to 12-week-old birds depleted hypothalamic SRIF stores and decreased the density of 125I-[Tyr1]-SRIF-binding sites in the caudal and cephalic lobes of the chicken pituitary gland. The reduction in SRIF content and in SRIF-binding sites occurred within 1 h of cysteamine administration and was maintained for at least 24 h. In 6-week-old birds, cysteamine (300 mg/kg) administration suppressed pituitary binding of 125I-[Tyr1]-SRIF for at least 5 days. Circulati concentrations of GH were markedly decreased 1 and 4 h after cysteamine injection, but not after 24 h.
Pituitary binding sites for 125I-[Tyr1]-SRIF were not affected by pretreatment of pituitary glands for 2–12 h in vitro with thyroxine or oestradiol-17β (1 nmol/l–10 μmol/l) or with ovine GH or recombinant DNA-derived chicken GH (1–100 μg/ml in vitro and 100–1000 μg/kg in vivo). Ovine prolactin, at concentrations of 1–100 μg/ml was also without effect on 125I-[Tyr1]-SRIF binding to pituitary membranes following a 2- or 4-h incubation with pituitary glands. Pituitary binding sites for 125I-[Tyr1]-SRIF were, however, increased after a 24-h incubation with 1 μmol tri-iodothyronine (T3)/l in vitro and 4 and 24 h after the administration of T3 (100–1000 μg/kg) in vivo. Although T3 had no direct inhibitory effect on 125I-[Tyr1]-SRIF binding to pituitary membranes, binding was suppressed 1 and 2 h after the in-vivo administration of T3 at concentrations of 100–1000 μg/kg.
These results therefore demonstrate homologous and heterologous regulation of SRIF-binding sites in the chicken pituitary gland.
Journal of Endocrinology (1990) 127, 417–425
Steroid fatty acid esters in adrenals and plasma: effects of ACTH
Authors: Bélanger B. , Caron S. , Bélanger A. , Dupont A. 
Published: December 2008

ABSTRACT
The presence and production of 5-ene-steroid fatty acid esters (SFA) has been previously reported in bovine adrenals. A study was conducted, using a series of chromatographic procedures and radioimmunoassays, to determine the levels of SFA in adrenals from man, cattle, dog, rat and guinea-pig, and to assess, in both rats and guinea-pigs, the effect of ACTH on SFA production by adrenals and their subsequent secretion into the circulation. The effects of ACTH on plasma SFA and non-conjugated steroid levels were also investigated in human subjects. Our data indicated that adrenal pregnenolone fatty acid ester (PREG-FA) levels were below 40% of PREG levels in cattle, dog, rat and guinea-pig while, in man, PREG-FA levels were threefold those of PREG. A large proportion of dehydroepiandrosterone (DHEA) and 5-androstene-3β,17β-diol were present as fatty acid ester derivatives in the adrenals of all species, with the exception of cattle. In both rats and guineapigs, administration of ACTH caused a sharp increase in adrenal PREG of approximately threefold which lasted for 6 h, while the concentration of adrenal PREG-FA was slightly increased for a short time. In plasma, however, a marked rise in PREG-FA occurred, while the changes in PREG levels were much lower than those of its acylated counterpart. In man, PREG and DHEA concentrations were rapidly stimulated two-fold in the first 30 min following the administration of ACTH, while PREG-FA and DHEA-FA levels were increased by approximately 2·5-fold (P<0·01) at 120 and 180 min. Our data suggest that there is a rapid turnover of SFA in adrenals which causes accumulation of non-polar steroids in the plasma.
Journal of Endocrinology (1990) 127, 505–511
Thyrotrophin-releasing hormone-induced growth hormone (GH) secretion in anaesthetized chickens: inhibition by GH-releasing factor at central sites
Authors: Ahene C. A. , Lea R. W. , Harvey S. 
Published: December 2008

ABSTRACT
Intracerebroventricular (i.c.v.) administration of GH-releasing factor (GRF) (at 1 or 10 μg) to anaesthetized immature (6- to 8-weeks-old) or adult (> 24-weeks-old) domestic fowl had no effect on basal GH concentrations in peripheral plasma, but suppressed (after 20 min) the acute GH response to exogenous (i.v.) thyrotrophin-releasing hormone (TRH) (1 μg/kg). The i.c.v. injection of GRF also reduced the content of somatostatin (SRIF) and dopamine (DA) in the hypothalamus, while increasing the concentration of the DA metabolite 3,4-dihydroxyphenyl acetic acid (DOPAC) and the DOPAC/DA ratio. The release of SRIF from hypothalamic tissue was stimulated in vitro by 100 nmol GRF/l. The inhibitory effect of i.c.v. GRF on TRH-induced GH secretion was blocked when it was simultaneously injected i.c.v. with SRIF antiserum.
These results demonstrate central effects of GRF on avian hypothalamic function and suggest an inhibitory role for this peptide in GH regulation, possibly mediated through increased SRIF secretion.
Journal of Endocrinology (1991) 128, 13–19
Long-term iodination of thyroglobulin by porcine thyroid cells cultured in porous-bottomed culture chambers: regulation by thyrotrophin
Authors: Gruffat D. , Gonzalvez S. , Chambard M. , Mauchamp J. , Chabaud O. 
Published: December 2008

ABSTRACT
Thyroid cells cultured as monolayers on the porous bottom of culture chambers have been shown to express some specific functions of thyroid follicles. This system, which allows independent access to apical and basal media, is suitable for the long-term study of polarized processes, as the cells maintain their polarized organization. Iodination of thyroglobulin has been investigated under different culture conditions in the presence or absence of TSH. Apical thyroglobulin accumulation, apical iodide concentration and thyroglobulin iodination have been followed simultaneously. Iodide (0·5 μmol/l) was added to basal medium at various stages: only once for 4-day incubations and at each medium change or daily for longer experiments. TSH increased the amount of thyroglobulin secreted into the apical medium by five- to sixfold, whereas high basal iodide concentrations (> 5 μmol/l) inhibited thyroglobulin secretion by TSH-stimulated cells. TSH increased iodide uptake giving an iodide concentration ratio between apical and basal media of about 5. Thyroglobulin iodination was dependent upon TSH. Thyroglobulin was iodinated only in the apical compartment. Secretion and iodination of thyroglobulin were polarized phenomena, but the polarity of iodination was total whereas the polarity of secretion was only partial (10% basal secretion). This functional asymmetry was maintained for up to 29 days. The maximal incorporation of iodine into thyroglobulin obtained was never higher than 3·5 atoms/mol. Apical iodide concentrations from 1 to 15 μmol/l, depending on culture conditions, did not increase this value. These results suggest that cells cultured in this culture system are able to reproduce several steps of thyroidal iodide metabolism although there may be unknown factors which could interfere and reduce the efficiency of thyroglobulin iodination.
Journal of Endocrinology (1991) 128, 51–61
Effects of exogenous porcine growth hormone on serum insulin-like growth factor-binding proteins in growing pigs
Authors: Coleman M. E. , Etherton T. D. 
Published: December 2008

ABSTRACT
The insulin-like growth factor-binding proteins (IGFBPs) in sera of growing pigs were partially characterized with respect to their size, immunological relationships to other known IGFBPs and their regulation by porcine (p) GH. Castrated male pigs (14–16 weeks of age) were treated with either vehicle or pGH (up to 100 μg/kg body weight per day) by daily i.m. injection for 7 days. Blood samples were collected by jugular venepuncture at the time of injection. Five IGFBPs of 43, 40, 34, 30 and 26 kDa were identified on ligand blots of porcine sera. A 30 kDa IGFBP, in addition to the 43 and 40 kDa IGFBPs, was immunoprecipitated by antiserum to pIGFBP-3 and found to contain N-linked carbohydrate suggesting that it is a fragment of pIGFBP-3 as has been noted for a 29 kDa N-glycosylated IGFBP in rat sera. The 34 kDa IGFBP in pig sera was precipitated by antisera to rat IGFBP-2 and contained no N-linked carbohydrate. Administration of pGH to normal growing pigs not only increased pIGFBP-3 levels but elicited a dose-dependent suppression of levels of the 34 kDa IGFBP as well. In summary, the Mr pattern of IGFBPs in the sera of growing pigs is similar to that observed in fetal and maternal pig sera and in other species. Furthermore, we report that administration of pGH to normal pigs suppresses the expression of an IGFBP-2-like IGFBP in pig sera while increasing expression of pIGFBP-3.
Journal of Endocrinology (1991) 128, 175–180
Pheromaxein, the pheromonal steroid-binding protein, is a major protein synthesized in porcine submaxillary salivary glands
Authors: Booth W. D. , von Glos K. I. 
Published: December 2008

ABSTRACT
Submaxillary salivary gland tissue from large White, Göttingen miniature and Meishan (Chinese) breeds of pig, and European wild boars, was incubated with [35S]methionine. The radiolabelled amino acid was incorporated into protein in all incubations as demonstrated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Specifically [35S]methionine was predominantly incorporated into the α- and β-charge isomers of pheromaxein, a 16-androstene steroid-binding protein, as shown by SDS-PAGE in combination with vertical isoelectric focusing on polyacrylamide slab gels. The synthesis of pheromaxein occurred in submaxillary gland tissue from both sexes, including tissues stored frozen at −70 °C for long periods. There was little evidence for pheromaxein synthesis in parotid gland tissue or skeletal muscle. Total protein, pheromaxein and total 16-androstenes were determined in the submaxillary gland cytosols of six mature Göttingen miniature boars and a positive correlation was found between these glandular constituents. The amounts of endogenous pheromaxein relative to total protein in the submaxillary gland cytosols (range 10·3–18·0%), together with the predominant synthesis of this protein in vitro, indicate that pheromaxein is a major protein produced in porcine submaxillary glands, particularly in those of the male.
Journal of Endocrinology (1991) 128, 205–212
Thyroidal iodine metabolism in obese-strain chickens before immune-mediated damage
Authors: Sundick R. S. , Herdegen D. , Brown T. R. , Dhar A. , Bagchi N. 
Published: December 2008

ABSTRACT
Several studies have shown that iodine plays a role in spontaneous autoimmune thyroiditis in man and other animals. In addition, abnormalities of iodine metabolism have been found in patients with Hashimoto's thyroiditis and in chickens of the obese strain (OS), an animal model of spontaneous autoimmune thyroiditis. We have examined several parameters of iodine metabolism before immune damage in this model and in the related Cornell strain (CS), a strain which develops a late-onset mild thyroiditis, to discover a possible causal relationship between altered iodine metabolism and the initiation of autoimmunity.
Thyroglobulin was purified from individual chicken thyroid glands and analysed for iodine by the ceric sulphate method. Analogous to the thyroglobulin of Hashimoto's patients, the iodine content of OS thyroglobulin (27 atoms/molecule) was lower than that of normal-strain thyroglobulin (46 atoms/molecule) when the chickens were provided with a normal diet. Also, under conditions of TSH suppression, the iodine content of OS thyroglobulin (18 atoms/molecule) was lower than that of CS thyroglobulin (36 atoms/molecule) and of normal-strain thyroglobulin (32 atoms/molecule). In contrast with Hashimoto's patients, however, the OS and CS chickens had practically no inorganic iodide in their thyroid glands; electrophoretic analysis of thyroid homogenates revealed that essentially all (> 99·62%) 125I was organified by 16 h in all strains of birds tested. Despite the relatively poor iodination of thyroglobulin exhibited by OS chickens, they did not iodinate additional 'unique' proteins, when examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of thyroid proteins labelled with 125I in vivo.
The release of 125I in vivo under conditions of TSH suppression was examined in chicks receiving thyroxine and propylthiouracil. After 14 days both OS and CS chicks showed poorly suppressible release of 85% and 92% respectively, while the normal strain released 33 %. To determine whether the autonomous function of OS and CS thyroid glands was present in a restricted number of follicles or cells or whether it occurred in a majority of cells, autoradiograms of thyroid glands labelled in vivo from TSH-suppressed chickens were examined. Silver grains were present in all cells, indicating that autonomous function was a characteristic of all cells.
These thyroid gland abnormalities are compared with those found in Hashimoto's patients and discussed in the context of their aetiological significance.
Journal of Endocrinology (1991) 128, 239–244
Increased nuclear tri-iodothyronine binding and thyroid hormone-stimulated glucose consumption in mononuclear blood cells from patients with liver cirrhosis
Authors: Kvetny J. , Matzen L. 
Published: December 2008

ABSTRACT
Nuclear tri-iodothyronine (T3) maximal binding capacity (MBC) and thyroxine- and T3-stimulated cellular oxygen consumption and glucose consumption were examined in mononuclear blood cells from six patients with liver cirrhosis (LC), in six patients with alcoholic hepatitis (AH), and in six healthy control subjects.
Serum T3 was decreased in patients with LC. The MBC of T3 was increased significantly (P < 0·05) in cells from patients with LC compared with patients with AH and controls, whereas the equilibrium association constants did not differ. Unstimulated glucose consumption was slightly increased (P < 0·05) in cells from patients with AH and LC compared with controls. Thyroid hormone-stimulated glucose consumption was significantly (P < 0·05) increased in cells from patients with LC compared with controls and patients with AH.
Unstimulated oxygen consumption did not differ between the groups, but thyroid hormone-stimulated oxygen consumption was depressed in cells from patients with AC (P < 0·05) compared with patients with LC and with controls.
We conclude that both thyroid hormone-stimulated glucose consumption and T3 nuclear receptor binding in cells from patients with LC are increased, and suggest that the observed changes are responsible for maintenance of euthyroidism in the face of reduced circulating T3.
Journal of Endocrinology (1991) 128, 321–325
The galactopoietic effect of bovine growth hormone in goats is associated with increased concentrations of insulin-like growth factor-I in milk and mammary tissue
Authors: Prosser C. G. , Royle C. , Fleet I. R. , Mepham T. B. 
Published: December 2008

ABSTRACT
Lactating goats exhibiting widely divergent responses to short-term (4 days) treatment with bovine GH (bGH) were retrospectively divided into two groups based on the magnitude of this response. There was no difference between groups in terms of the pretreatment milk yield, but by day 4 of treatment milk secretion had increased by 4·99±2·5 (s.e.m.) ml/h (P > 0·05 compared with pretreatment) for group 1 and 22·9±2·4 ml/h (P< 0·001) for group 2. Plasma GH increased in both groups, but concentrations were significantly higher both before and during treatment in group 1 compared with group 2. Plasma concentrations of insulin-like growth factor-I (IGF-I) increased significantly during bGH treatment for both groups and there was no significant difference between the two until day 4 of treatment when levels of IGF-I in group 1 began to decline, whereas those from group 2 were maintained. Concentrations of IGF-I in milk from goats in group 1 were not significantly altered by GH administration, whereas those in goats in group 2 were increased by 40% (P < 0·01 compared with pretreatment). Levels of IGF-I in mammary secretory tissue from four animals from group 1 were not altered by bGH (2·8±0·2 and 2·77 ±0·08 nmol/kg tissue before and after treatment respectively), but were significantly (P < 0·05) increased in four animals from group 2 (2·80±0·2 and 9·9±1·1 nmol/kg tissue). Thus, it appears that the galactopoietic response in goats was associated with significantly lower levels of GH in plasma after 3 days of treatment and, more strikingly, greater amounts of IGF-I in milk and mammary tissue. This latter observation is consistent with the hypothesis that the effects of bGH on the mammary gland itself are mediated by IGF-I and that the availability of IGF-I to mammary tissue is an important component of the overall galactopoietic response to bGH.
Journal of Endocrinology (1991) 128, 457–463
[125I]Iodomelatonin-binding sites in the pigeon brain: binding characteristics, regional distribution and diurnal variation
Authors: Yuan H. , Pang S. F. 
Published: December 2008

ABSTRACT
The binding and pharmacological characteristics of melatonin-binding sites labelled by [125I]iodomelatonin in membrane preparations from the pigeon brain were determined. Specific binding of [125I]iodomelatonin in the membrane preparations of pigeon brain was rapid, stable, saturable and reversible. The [125I]iodomelatonin-binding sites had the following order of pharmacological affinities: melatonin > 6-chloromelatonin > N-acetylserotonin > > 5-hydroxytryptamine > tryptamine > 5 -methoxytryptophol, > 1 - acetylin dole-3-carboxytryptamine, 5-hydroxyindole-3-acetic acid, l-tryptophan and 3-acetylindole. Compounds known to act on serotonin receptors, adrenoceptors or cholinoceptors were inactive compared with melatonin. Of the various brain regions studied, melatonin binding was greatest in the hypothalamus, intermediate in the mid-brain, pons-medulla and telencephalon, and low in the cerebellum. Subcellular fraction studies indicated that 39% of the binding was located in the mitochondrial fraction, 34% in the nuclear fraction, 21% in the microsomal fraction and 5·6% in the cytosol fraction. Scatchard analysis of the membrane preparations revealed a dissociation constant (Kd) of 206·3±57·9 pmol/l and a total number of binding sites (Bmax) of 26·7±1·9 fmol/mg protein in the middle of the light period (mid-light). In addition, saturation studies demonstrated that [125I]iodomelatonin-binding sites in pigeon brain membrane preparations were 36·2% higher at mid-light (26·7±1·9 fmol/mg protein) than in the middle of the dark period (19·6±1·25 fmol/mg protein), with no significant variation in their binding affinities.
Journal of Endocrinology (1991) 128, 475–482
GROWTH HORMONE RECEPTOR GENE: NOVEL EXPRESSION IN PITUITARY TISSUE
Authors: Fraser R.A. , Siminoski K. , Harvey S. 
Published: December 2008

ABSTRACT
Specific hybridization of polyadenylated RNA, extracted from rat, rabbit and human pituitary glands with a 638 bp rabbit GH receptor (rGHR) cRNA was demonstrated by Northern analysis. In-situ hybridization of tissue sections with the probe demonstrated the localization of rGHR mRNA throughout the rat pituitary gland and its presence in the anterior lobe of the rabbit pituitary. Growth hormone binding sites on pituitary membranes were not, however, demonstrated by radioligand binding studies. Thus, although the GH receptor gene is expressed in pituitary tissue, functional GH receptors may not be inserted into pituitary plasma membranes.
ATRIAL NATRIURETIC FACTOR STIMULATES IN-VIVO AND IN-VITRO SECRETION OF CORTISOL IN TELEOSTS
Authors: Arnold-Reed D.E. , Balment R.J. 
Published: December 2008

ABSTRACT
Atrial natriuretic factor (ANF) has been shown to increase circulating cortisol levels in cannulated, free-swimming seawater (SW)-adapted flounders. Increases were apparent within 30 min of i.v. injection of human ANF hANF; 10μg/kg bw) and the increase in plasma cortisol was maintained throughout the 5h experimental period. No such increase was observed in vehicle-injected controls. This apparent steroidogenic effect of ANF was supported by an ANF-induced increase in in-vitro secretion of cortisol by interrenal tissue from SW-adapted trout. By contrast hANF had no significant effect on tissue derived from freshwater adapted trout. An ANF-induced increase in plasma cortisol by a direct effect on interrenal steroidogenesis in SW teleosts would be an appropriate response for survival in hypertonic media.
Influence of oxytocin on sodium excretion in the anaesthetized Brattleboro rat
Authors: Brimble M. J. , Balment R. J. , Smith C. P. , Windle R. J. , Forsling M. L. 
Published: December 2008

ABSTRACT
The contribution of oxytocin to the maintenance of renal Na+ excretion in the Brattleboro rat has been examined in animals infused with hypotonic saline. Brattleboro rats exhibited hypernatraemia and hyperosmolality associated with greatly increased plasma concentrations of oxytocin by comparison with Long–Evans control rats. Neurohypophysectomy to remove the secretion of the remaining posterior pituitary peptide, oxytocin, led to greatly diminished rates of Na+ excretion in the Brattleboro rat. Oxytocin replacement to achieve plasma levels equivalent to those in intact Brattleboro rats produced a substantial and sustained natriuresis in the neurohypophysectomized animal. Oxytocin secretion evoked in response to saline infusion would thus appear to be effective in promoting renal Na+ excretion in the absence of vasopressin in the Brattleboro rat.
Journal of Endocrinology (1991) 129, 49–54
Action of pituitary adenylate cyclase-activating polypeptide and vasoactive intestinal polypeptide on the rat vascular system: effects on blood pressure and receptor binding
Authors: Nandha K. A. , Benito-Orfila M. A. , Smith D. M. , Ghatei M. A. , Bloom S. R. 
Published: December 2008

ABSTRACT
The N-terminal fragment (PACAP 27) of the novel neuropeptide, pituitary adenylate cyclase-activating polypeptide 38 (PACAP 38), has 68% homology with vasoactive intestinal polypeptide (VIP). The administration of bolus doses of PACAP 38 and its 27 amino acid N-terminal fragment (PACAP 27) caused a rapid but transient dose-dependent hypotensive effect in the anaesthetized rat. The amplitude and duration of the response obtained by PACAP 38 was comparable with VIP whereas PACAP 27 was three times less potent than VIP. Furthermore, radioreceptor binding studies demonstrated that 125I-labelled PACAP 27 and 125I-labelled VIP bound to membranes prepared from blood vessels. Both PACAP 27 and VIP were capable of displacing the other from these binding sites. We propose that the hypotensive effect is via the same receptor type.
Journal of Endocrinology (1991) 129, 69–73