bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and evaluation of an immunoenzymometric assay for the chicken progesterone receptor
Authors: Bläuer M. K. , Tuohimaa P. J. , Vilja P. J. 
Published: December 2008

ABSTRACT
A specific and sensitive immunoenzymometric assay (IEMA) was developed for measuring the quantity of chicken progesterone receptor (PR) in tissue cytosol. The assay uses two monoclonal antibodies to the PR. One is used to capture the PR. The second (labelled with biotin) reacts first with the captured receptor and subsequently with avidin-labelled horseradish peroxidase to provide an enzymatic end-point. The method has a determination range from 0·3 to 60 pmol/l. Intra- and interassay coefficients of variation were 3·7% and 9·0% respectively. The assay can be performed with equal results as a rapid (3 h) or an overnight procedure. The IEMA is convenient, especially for signal measurement and the calculation of results. No ultracentrifugation of samples is needed, since the IEMA can be performed on low-speed cytosol samples. Assay results correlated well (r = 0·927) with those obtained by the conventional ligand-binding assay used in our laboratory. Similar results were obtained with the IEMA and the ligand-binding assay after exposure of cytosol samples to increased temperatures: at 20 °C the PR remained stable for the 4-h period examined, whereas at 37 °C almost complete degradation of the PR was observed in 30 min. Being more than 100 times as sensitive as the ligand-binding assay, the IEMA enabled the quantification of PR for the first time in such tissues as the bursa and small intestine even of immature animals.
Journal of Endocrinology (1991) 129, 189–196
An autoradiographical study of binding sites for vasopressin located on corticotrophs in rat and sheep pituitary glands
Authors: Du Pasquier D. , Dreifuss J. J. , Dubois-Dauphin M. , Tribollet E. 
Published: December 2008

ABSTRACT
Arginine vasopressin (AVP) carried by hypophysial portal blood acts in the pituitary gland, in synergy with corticotrophin-releasing factor (CRF), to induce ACTH secretion. The relative importance of AVP and CRF in this secretory response depends upon the nature and intensity of stressful stimuli, and perhaps also on the species. The aim of the present work was to study, in isolated rat and sheep pituitary glands, the topography of binding sites for AVP and to establish whether they are indeed associated with corticotrophs. To this end, we performed contact autoradiography on tritium-sensitive film using 1·5–2·0 nmol [3H]AVP/l as ligand. ACTH immunoreactivity was detected on sections immediately adjacent to those used for autoradiography. In both species, specific binding sites for AVP were only present in the anterior lobe; the intermediate lobe was not labelled and the neural lobe showed non-specific labelling. Autoradiograms from experiments using [3H]AVP in competition with different synthetic structural analogues showed that, in rat and sheep anterior pituitary glands, receptors differ from the V1 and V2 subtypes.
Specific [3H]AVP-binding sites formed an irregular, patchy pattern throughout the anterior lobe. In both species, this pattern was strikingly similar to that formed by cell clusters showing ACTH immunoreactivity, indicating that the AVP-binding sites are associated with the corticotrophs. Immunoreactive cells in the intermediate lobe had no [3H]AVP-binding sites. [3H]AVP binding was more intense in the sheep than in the rat anterior lobe, suggesting that AVP may be particularly important for ACTH secretion in the sheep.
Journal of Endocrinology (1991) 129, 197–203
Lipoprotein lipase in guinea-pig adrenals: activity, mRNA, immunolocalization and regulation by ACTH
Authors: Gåfvels M. , Vilaró S. , Olivecrona T. 
Published: December 2008

ABSTRACT
Lipase activity in homogenates of guinea-pig adrenals was studied under conditions which exclude the hormone-sensitive lipase/cholesterol ester hydrolase. Antibody inhibition and chromatography on heparin–Sepharose showed that most of the activity was due to lipoprotein lipase (LPL), and that there was only a small amount of hepatic lipase activity. Northern blot analysis of total RNA demonstrated the same three adrenal LPL mRNA species (1·8, 3·1 and 3·5 kb) as were found in adipose tissue and heart. Hence, at least part of the LPL activity in adrenals is due to enzyme synthesized within the tissue. Immunolocalization showed that LPL was associated with the endothelium of blood vessels throughout the gland. In addition, there was cytoplasmic immunoreaction, suggesting that lipase was synthesized in a subpopulation of cells in the transitional zone between the fasciculata and reticularis layer of the cortex, particularly over lipid-filled cells. There was also intense immunofluorescence over scattered cells in the adrenal medulla. Treatment with an ACTH analogue depot (20 IU, i.m.) for 11 days induced a 12-fold increase in serum cortisol and increased adrenal weight 2·2-fold. The treatment induced increases in LPL mRNA (about twofold), LPL activity and in the number of cells in the adrenal cortex which gave an immunoreaction for LPL.
Journal of Endocrinology (1991) 129, 213–220
Involvement of ovarian steroids and endogenous opioids in the fasting-induced suppression of pulsatile LH release in ovariectomized rats
Authors: Cagampang F. R. A. , Maeda K.-I. , Tsukamura H. , Ohkura S. , Ôta K. 
Published: December 2008

ABSTRACT
The participation of the ovarian steroids and opioid peptides in the suppression of pulsatile LH release during acute fasting was examined in rats. Ovariectomized rats bearing silicone elastomer implants of oestradiol and/or progesterone were fasted for 48 h and subsequently blood samples were taken every 6 min for 3 h. Pulsatile LH release was suppressed after 48 h of fasting in the ovariectomized rats implanted with oestradiol but not in the oil-implanted controls. This suppression was enhanced after the administration of progesterone together with oestradiol.
In a second experiment, ovariectomized rats bearing implants of oestradiol or oil were fasted for 48 h and injected s.c. (2·5 mg/kg body weight) with an opioid antagonist, naloxone hydrochloride, immediately before blood sampling. In the fasted oestradiol-treated ovariectomized rats, naloxone was able to prevent the suppression of pulsatile LH release. In the absence of oestradiol, however, naloxone was without effect on LH release in either the fasted or unfasted animals.
These experiments indicate that the suppression of pulsatile LH release after 48 h of fasting is dependent upon oestradiol and that endogenous opioids are involved in the suppression.
Journal of Endocrinology (1991) 129, 321–328
Long-term hyperprolactinaemia reduces basal but not androgen-stimulated oestradiol production in small antral follicles of the rat ovary
Authors: Jonassen J. A. , Baker S. P. , McNeilly A. S. 
Published: December 2008

ABSTRACT
Hyperprolactinaemia disrupts fertility in many species, perhaps by inhibiting ovarian follicular steroidogenesis. The present studies measured oestradiol and progesterone secretion from isolated follicles from rats rendered hyperprolactinaemic in one of two ways. Sustained hyperprolactinaemia was induced by transplantation of two donor pituitary grafts under the renal capsule of adult female rats; grafts remained in place for 3 months. Transient hyperprolactinaemia was induced by pseudopregnancy initiated by cervical stimulation. Small antral follicles were isolated from both groups of rats 8–10 days after the previous vaginal oestrous smear and also from a control group of dioestrous female rats. Follicles were incubated for 3 h in the presence or absence of human chorionic gonadotrophin (hCG) or testosterone. Basal and hCG-stimulated oestradiol production were each reduced in follicles from both hyperprolactinaemic groups, relative to follicles from dioestrous control rats. In contrast, in the presence of testosterone, all groups of follicles produced comparable amounts of oestradiol. hCG stimulated comparable progesterone production by follicles from all three treatment groups. Testosterone elicited smaller increases in progesterone accumulation by follicles from all in-vivo groups. Reduced basal and gonadotrophin-stimulated, but not androgen-stimulated, oestradiol accumulation suggests that androgen production rather than aromatase activity in small antral follicles may be impaired by long-term hyperprolactinaemia.
Journal of Endocrinology (1991) 129, 357–362
Progesterone ensures full-length luteal phases during the breeding season in ewes
Authors: Legan S. J. , I'Anson H. , Neiser P. 
Published: December 2008

ABSTRACT
To test the hypothesis that each luteal-phase increase in the serum concentration of progesterone throughout the breeding season prevents a short luteal phase in the next cycle, 22 ewes were treated with an i.v. injection of 10 μg gonadotrophin-releasing hormone (GnRH) agonist every 12 h for 33 days beginning on day 12 of a cycle synchronized with prostaglandin F2α. Six days after the last injection of GnRH agonist, ten of the ewes were treated s.c. for 14 days with progesterone-containing silicone elastomer implants to generate luteal-phase serum concentrations. Twenty ewes stopped cycling during GnRH agonist treatment and 16 of these, eight controls and eight treated with progesterone, resumed cycling after the end of treatment. In the control ewes, oestrous cycles began 25·0±7·5 (s.e.m.) days after the end of GnRH agonist administration, a short luteal phase preceding initiation of cycles in six ewes. In contrast, all eight progesterone-treated ewes resumed cycling synchronously 22·0 ±0·2 days after the end of GnRH agonist treatment and all began with full-length luteal phases. These results support the hypothesis that each luteal-phase increment in the serum concentration of progesterone throughout the breeding season prevents a short luteal phase in the next cycle.
Journal of Endocrinology (1991) 129, 371–379
Effects of two synthetic parathyroid hormone-related protein fragments on maternofetal transfer of calcium and magnesium and release of cyclic AMP by the in-situ perfused rat placenta
Authors: Shaw A. J. , Mughal M. Z. , Maresh M. J. A. , Sibley C. P. 
Published: December 2008

ABSTRACT
Two human parathyroid hormone-related protein (hPTHrP) fragments were tested for effects on maternofetal transfer of 45Ca and Mg across the in-situ perfused rat placenta at 21 days of gestation (term = 23 days). The fetal placental circulation was perfused with a Mg-free Krebs–Ringer solution and the unidirectional maternofetal clearance (Kmf) of 45Ca and Mg compared with that of 51Cr-EDTA, the latter being employed as a paracellular diffusional marker. Placental perfusion with hPTHrP(1–34) (100 ng/ml) or hPTHrP(75–86)amide (50 ng/ml) did not significantly alter the Kmf of 45Ca or that of Mg. In separate rats, however, hPTHrP(1–34) but not hPTHrP(75–86)amide stimulated marked placental cyclic AMP (cAMP) release, the peak response of 63±7 pmol/min occurring 10 min after the beginning of the peptide perfusion. A lower dose of hPTHrP(1–34) (4 ng/ml) produced a similar peak release of cAMP, as did [Nle8,21,Tyr34]-rPTH(1–34)amide (4 ng/ml) and the adenylate cyclase agonist forskolin (17 μmol/l). Forskolin also rapidly increased the Kmf of 45Ca but not that of Mg or 51Cr-EDTA. The present study indicates that hPTHrP does not acutely affect maternofetal transfer of Ca or Mg across the perfused rat placenta. The data also question the role played by cAMP in the stimulatory actions of forskolin on placental Ca transport.
Journal of Endocrinology (1991) 129, 399–404
Different mechanisms for the inhibition of progesterone secretion by ACTH and corticosterone in pregnant rats
Authors: Sugino N. , Tamura H. , Nakamura Y. , Ueda K. , Kato H. 
Published: December 2008

ABSTRACT
The present study investigated possible sites through which ACTH or corticosterone inhibit progesterone secretion in pregnant rats, and the role of placental factors in blocking the inhibitory effect. The number of conceptuses was adjusted to one (1C group) or more than ten (FC group) on day 7 of pregnancy by aspirating the desired number. Serum concentrations of progesterone, testosterone and oestradiol were significantly (P<0·01) lower on day 15 in the 1C group than in the FC group. Corpora lutea (CL) obtained on day 15 were incubated for 6 h with corticosterone or ACTH. Corticosterone (1 μmol/l) significantly (P<0·05) inhibited progesterone secretion in the IC group but not in the FC group. The inhibitory effect of corticosterone in the IC group was completely blocked by co-addition of 1 μmol testosterone/l or 1 μmol oestradiol/l but not by 1 μmol dihydrotestosterone/l. ACTH (1 μg/l–1 mg/l) had no direct effect on progesterone secretion in either the IC or the FC groups, although ACTH apparently decreases progesterone secretion in vivo. Placentae obtained from rats of the FC group on day 15 were incubated for 24 h with or without ACTH (1 mg/l). The supernatant after placental incubation without ACTH significantly (P<0·01) increased progesterone secretion by the CL in both the IC and FC groups, and also eliminated the inhibitory effect of corticosterone in the IC group. The supernatant after placental incubation with ACTH also increased progesterone secretion in the FC group as effectively as the supernatant from the control incubation, but it had no effect in the IC group. It is concluded that corticosterone directly inhibits progesterone secretion by the CL, whereas the inhibitory effect of ACTH is mediated through the placenta. The results indicate that these inhibitory effects of corticosterone or ACTH are eliminated if the CL has been exposed to enough placental hormones before day 15 of pregnancy.
Journal of Endocrinology (1991) 129, 405–410
Immunocytochemical and morphometric studies of mammotrophs, somatotrophs and somatomammotrophs in sheep pituitary cell cultures
Authors: Thorpe J. R. , Wallis M. 
Published: December 2008

ABSTRACT
Alterations occurring when sheep anterior pituitary cells are placed in culture for 4 days were studied using electron microscopy and immunogold labelling. The majority of cells present showed marked morphological changes during culture, with degranulation and development of extensive rough endoplasmic reticulum. The proportions of somatotrophs and mammotrophs, as identified by immunogold labelling, fell during culture. The majority (70%) of somatotrophs showed relatively little degranulation but the remainder were extensively degranulated after 4 days in culture, suggesting two subpopulations of this cell type. Conversely, most (80%) of the mammotrophs showed extensive degranulation after culture, but one-fifth remained heavily granulated, suggesting that mammotrophs too are heterogeneous. The proportion of cells labelling for both GH and prolactin (somatomammotrophs) increased during culture to about 3% of the cells present, compared with <0·2% of all cells before culture.
Journal of Endocrinology (1991) 129, 417–422
Expression of parathyroid hormone-related protein in abnormal human parathyroids
Authors: Docherty H. M. , Ratcliffe W. A. , Heath D. A. , Docherty K. 
Published: December 2008

ABSTRACT
The expression of parathyroid hormone-related protein (PTHrP) in abnormal human parathyroids was investigated. Northern blot analysis of RNA extracted from human benign parathyroid adenomata (n = 4) revealed multiple PTHrP mRNA species ranging in size from 1·8 to 4kb. The relative abundance of PTHrP mRNA expressed in two of the adenomata was similar to that of a tumour (DAF) associated with humoral hypercalcaemia of malignancy, whereas PTHrP mRNA was of low abundance in a third and was undetectable in the fourth. PTHrP-like immunoreactivity was detected in extracts of abnormal parathyroid tissue (benign adenoma (n = 7), hyperplasia (n = 5) and parathyroid carcinoma (n = 2)) using a sensitive specific two-site immunoradiometric assay for human (h) PTHrP(1–86) and a radioimmunoassay for hPTHrP(1–34). Ratios of hPTHrP(1–86)- and hPTHrP(1–34)-like immunoreactivities relative to hPTH(1–84)-like immunoreactivity in the parathyroid tissue extracts were, on average, less than 1%. PTHrP bioactivity in the extracts could not be distinguished from that of PTH, by an osteosarcoma cell bioassay. We conclude that, despite reports of over-expression of PTHrP mRNA in parathyroid adenomata, the potential contribution of PTHrP to the total PTH-like activity of adenomata and other abnormal parathyroid tissue may be insignificant relative to PTH.
Journal of Endocrinology (1991) 129, 431–438
PYROGLUTAMYLGLUTAMYLPROLINEAMIDE IS PRESENT IN RAT ANTERIOR AND POSTERIOR PITUITARY GLAND
Authors: Ashworth R.J. , Morrell J.M. , Aitken A. , Patel Y. , Cockle S.M. 
Published: December 2008

ABSTRACT
A new TRH-like peptide pyroglutamylglutamylprolineamide (pGlu-Glu-ProNH2) has recently been purified and characterized from both the rabbit prostate complex and human semen. In this study, TRH-immunoreactive peptides were extracted from anterior pituitary, posterior pituitary and hypothalamus and subjected to gel exclusion chromatography. For each tissue, TRH was resolved from pGlu-Glu-ProNH2 by anion-exchange chromatography at pH 7.6 In the anterior pituitary, 63% of the TRH immunoreactivity was chromatographically identical to pGlu-Glu-ProNH2 whereas in the posterior pituitary the new peptide represented less than 5% of the total TRH immunoreactivity. Only trace levels of pGlu-Glu-ProNH2 were observed in hypothalamus, suggesting that the acidic TRH-related peptide found in the anterior pituitary may not be of hypothalamic origin. The new TRH-like peptide was purified from whole pituitaries by gel exclusion and ion-exchange chromatography, followed by high power liquid chromatography and was shown to have chromatographic properties identical to pGlu-Glu-ProNH2. Amino acid analysis of the purified peptide revealed glutamic acid and proline residues in the ratio Glx:2 Pro:1, which is the expected composition of pGlu-Glu-ProNH2 after acid hydrolysis.
The effects of insulin-like growth factor-I (IGF-I), IGF-II and des(1–3)IGF-I, a potent IGF analogue, on growth hormone and IGF-binding protein secretion from cultured rat anterior pituitary cells
Authors: Simes J. M. , Wallace J. C. , Walton P. E. 
Published: December 2008

ABSTRACT
The effects of insulin-like growth factor-I (IGF-I), IGF-II and des(1–3)IGF-I, a potent IGF-I analogue, on the secretion of GH and IGF-binding protein (IGFBP) from cultured rat anterior pituitary cells were measured. IGF-I and des(1–3)IGF-I stimulated GH secretion at low concentrations (maximally effective at 1 and 0·1 μg/l respectively) and inhibited GH secretion at higher concentrations. The half-maximal inhibitory concentrations (IC50) were approximately 20 μg/l and 1 μg/l for IGF-I and des(1–3)IGF-I respectively. Thus des(1–3)IGF-I was more potent than IGF-I in these effects on GH secretion. We postulate that the increased potency of des(1–3)IGF-I in affecting GH secretion is due to decreased binding of this peptide by pituitary IGFBP compared with IGF-I. In contrast with IGF-I and des(1–3)IGF-I, IGF-II did not stimulate GH secretion at low concentrations, but did inhibit GH secretion from pituitary cells with an IC50 of approximately 20 μg/l.
Several IGFBPs ranging in molecular mass from 22 000 to 52 000 were detected in medium conditioned by cultured anterior pituitary cells. When measured by Western-ligand blotting and competitive ligand-binding techniques, these IGFBPs exhibited decreased binding of des(1–3)IGF-I compared with IGF-I and IGF-II. The production of IGFBP by anterior pituitary cells was stimulated by the addition of IGFs to the culture medium.
Journal of Endocrinology (1991) 130, 93–99
Evidence for temporal coupling of growth hormone, prolactin, LH and FSH pulsatility overnight during normal puberty
Authors: Dunger D. B. , Matthews D. R. , Edge J. A. , Jones J. , Preece M. A. 
Published: December 2008

ABSTRACT
The patterns of secretion of GH, LH, FSH and prolactin were determined over a single night (20.00–08.00 h; 15-min sampling) in 34 normal subjects (17 male, 17 female, aged 9·1–20·9 years). Plasma GH was measured by an immunoradiometric assay and LH, FSH and prolactin by radioimmunoassay in all samples. Data were analysed by Fourier transformation and cross-correlation after stationarization.
The highest mean GH levels were noted in girls at Tanner stage 2/3 and in boys at stages 4/5. Prolactin levels were highest in girls at stage 4/5 and in boys at stage 2/3. LH and FSH showed a progressive rise by puberty stage in both sexes. The dominant pulse periodicities of GH and prolactin were 150–180 min in girls and 180 min in boys. LH and FSH pulse periodicity was around 90 min in early puberty and 180 min in later puberty in both sexes. LH and prolactin pulses showed a phase relationship with GH with a lag of 30–75 min (r = 0·32; P < 0·001) and 30 min (r = 0·47; P < 0·0001) respectively. Generally, LH and prolactin pulses were in phase (r = 0·42; P < 0·0001) and there was a highly significant correlation (r = 0·64; P < 0·0001) between FSH and LH pulsatility.
Whereas mean overnight concentrations and pulse periodicity of the principal pituitary hormones varied between the sexes during early puberty, by the end of puberty a dominant pulse periodicity of around 150–180 min was established and there was remarkable temporal coupling of pulsatility.
Journal of Endocrinology (1991) 130, 141–149
Do in-vivo suppression and stimulation of lipolysis influence thyroid hormone levels in man?
Authors: Newrick P. G. , Braatvedt G. , Stansbie D. , Corrall R. J. M. 
Published: December 2008

ABSTRACT
To determine whether increases in non-esterified fatty acids alter free thyroid hormone and TSH levels, the effect of endogenous activation of lipolysis by insulin-induced hypoglycaemia was examined in seven healthy volunteers pretreated with placebo or acipimox. Whilst levels of non-esterified fatty acid were very different in the two groups, levels of free thyroxine, tri-iodothyronine and TSH were unchanged. Thus, within the range of non-esterified fatty acid levels likely to be seen in clinical practice, any effect on thyroid hormone measurements can be safely ignored.
Journal of Endocrinology (1991) 130, 155–157
Appearance of β-human atrial natriuretic peptide in collagen disease
Authors: Shichiri M. , Miyasaka N. , Hirata Y. , Ando K. , Marumo F. 
Published: December 2008

ABSTRACT
To elucidate the circulating forms of human atrial natriuretic peptide (hANP) in collagen disease, we analysed plasma samples obtained from 21 patients with systemic lupus erythematosus, rheumatoid arthritis or progressive systemic sclerosis with no clinical evidence of cardiac involvement. The findings were compared with those obtained from 21 healthy control subjects. Plasma hANP-like immunoreactivity was normal in all but three of the controls and in two patients with the nephrotic syndrome due to lupus nephritis. Reverse-phase high-performance liquid chromatography, gel permeation chromatography and subsequent radioimmunoassay for hANP revealed that the circulating hANP consisted of α-hANP, β-hANP and γ-hANP in the patients with collagen disease whereas α-hANP predominated in the control group. β-hANP appeared in 18 of the 21 patients but was not observed in the controls. These data suggest that β-hANP circulates in the plasma of patients with collagen disease even when no myocardial involvement is apparent and that the appearance of β-hANP is not always associated with an increase in total plasma hANP-like immunoreactivity. Thus the appearance of β-hANP in plasma is not a phenomenon specific to congestive heart failure.
Journal of Endocrinology (1991) 130, 159–161