bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucocorticoid inhibition of stimulus-evoked adrenocorticotrophin release caused by suppression of intracellular calcium signals
Authors: Antoni F. A. , Hoyland J. , Woods M. D. , Mason W. T. 
Published: December 2008

ABSTRACT
Stress provokes a cohort of homeostatic reflexes by the central nervous, the immune as well as the metabolic control systems of the body. These powerful adaptive responses, which can cause a collapse of body homeostasis in the absence of feedback inhibition, are suppressed by adrenal glucocorticoid hormones. A prominent and physiologically significant early action of glucocorticoids that requires the induction of newly synthesized messenger RNA and protein is the suppression of ACTH release by anterior pituitary corticotroph cells. It is demonstrated here that glucocorticoids inhibit stimulated ACTH secretion in pituitary corticotroph tumour (AtT-20) cells by reducing stimulus-evoked intracellular free calcium transients. Thus, the data show for the first time that intracellular calcium signals may be modified by rapidly induced proteins. It is proposed that this is a general mechanism that underlies the early inhibitory effects of glucocorticoids during stress in various types of cell.
Abnormal maternal behaviour in mice previously immunized against progesterone
Authors: Wang M.-W. , Heap R. B. , Taussig M. J. 
Published: December 2008

ABSTRACT
Anti-progesterone immunization leads to reversible infertility in mice; this can be achieved by passive immunization with a monoclonal antibody to progesterone (DB3), or by active immunization with either a progesterone–protein (bovine serum albumin; BSA) conjugate or anti-idiotype directed against DB3. Recovery of fertility in treated females varied from 39·5 to 75·5 median days after passive or active (progesterone–BSA) immunization respectively. Litter size after the first pregnancy also differed from 8·6 ±0·8 to 5·0 ±0·6 (mean ± s.e.m.) per mother after passive or active immunization respectively. When litter size was standardized to a maximum of four pups per litter, aberrant maternal responses were observed in the first 5 days after delivery in 40–70% of the nursing mothers. These responses took the forms of cannibalism and failure to retrieve or to nurse pups and resulted in a high incidence of pup rejection (up to 40%), compared with no rejection in control mothers. When mothers were allowed to keep entire litters, an even higher incidence of pup rejection occurred (51% compared with 8% in controls). There was an apparent relation between the degree of negative maternal behaviour and the progesterone antibody concentration in the circulation during the infertile period. Whereas aberrant behaviour occurred mainly within the first 5 days of lactation, it was significantly reduced thereafter. Aberrant behaviour of the mother towards pups may be a consequence of the presence of residual progesterone antibodies in the circulation which affects the process of progesterone withdrawal at parturition that is essential for the establishment of normal maternal responses to the neonate.
Journal of Endocrinology (1992) 134, 257–267
Resistance to parathyroid hormone-induced inhibition of inorganic phosphate transport in opossum kidney cells cultured in low inorganic phosphate medium
Authors: Caverzasio J. , Bonjour J.-P. 
Published: December 2008

ABSTRACT
Renal resistance to the phosphaturic action of parathyroid hormone (PTH) is observed during dietary deprivation of inorganic phosphate (Pi) in vivo. In the present work, the influence of short (3 h)- or long (72 h)-term deprivation of Pi on the effect of bovine PTH (bPTH(1–34)) on both Na-dependent Pi transport and cyclic AMP(cAMP) production was examined in cultured opossum kidney epithelium. Na-dependent Pi transport increased by 100% in cells exposed to low Pi medium containing no Pi (LPM) for 3 h, as compared with transport in high Pi medium containing 2 mmolPi/l (HPM). In response to a submaximal dose (1 nmol/l) of bPTH(1–34), Na-dependent Pi transport was similarly inhibited by about 40% in LPM and HPM. This inhibition was preceded by increased cAMP production which was identical in LPM and HPM. In opossum kidney cells exposed for 72 h to LPM, Na-dependent Pi transport was also increased by 100% compared with that in HPM. However, bPTH(1–34) added at 1 nmol/l did not induce any significant change in Na-dependent Pi transport or cAMP. Stimulation of cAMP could only be elicited at bPTH(1–34) concentrations higher than 1 nmol/l. Such a reduced cAMP response was also observed with forskolin in cells incubated for 72 h in LPM. The cellular resistance to the generation of cAMP was associated with a significantly lower level of ATP in cells cultured for 72 h in LPM compared with ATP levels in HPM. There was a good relationship between cellular ATP level and expression of the inhibitory effect of bPTH on Pi transport in culture media containing various concentrations of Pi. In conclusion, long-term Pi depletion in opossum kidney cells leads to cellular resistance to PTH-induced cAMP generation and inhibition of Pi transport. The lower level of cAMP in Pi-depleted cells is probably due to insufficient substrate for cAMP generation. It is likely that other ATP-dependent processes involved in cellular Pi transport regulation might also be affected in the severely Pi-depleted cells and contribute to the resistance of PTH action on Pi transport inhibition.
Journal of Endocrinology (1992) 134, 361–368
Primiparous rhesus monkey mothers are more sensitive to the nursing-induced inhibition of LH and ovarian steroid secretion
Authors: Wilson M. E. 
Published: December 2008

ABSTRACT
The duration of lactational infertility is prolonged significantly in adolescent, primiparous rhesus monkey (Macaca mulatta) mothers compared with adult, multiparous mothers. The present study examined the hypothesis that this parity/age difference in lactational infertility is due to a difference in the physiological responsiveness to nursing behaviour between adolescent and fully adult mothers and is not a consequence of differences in nursing behaviour, per se. At 22 weeks postpartum, mother–infant pairs were randomly assigned to one of four conditions: primiparous, nursing restricted (PR; n=9); primiparous, nursing unrestricted (PU; n= 11); multiparous, nursing restricted (MR; n= 12); and multiparous, nursing unrestricted (MU; n=8). Nursing was restricted for a 2-week period by mothers wearing a primate vest which prevented suckling behaviour but allowed infants to interact with their mothers. Nursing restriction resulted in a significant increase in serum oestradiol concentrations in both PR and MR mothers. Although nursing bout frequencies and durations were similar between PU and MU mothers, serum oestradiol also rose in MU mothers but remained suppressed in PU mothers. Once the nursing manipulation period ended and all mothers were allowed to nurse ad libitum, serum oestradiol concentrations continued to rise in all but the PU mothers. This brief interruption of nursing at 22 weeks postpartum advanced the subsequent timing of the first postpartum ovulation in MR and PR mothers relative to that of PU mothers. Again, despite similarities in nursing behaviour, the occurrence of first ovulation was also advanced in MU mothers compared with PU mothers.
Just prior to the first postpartum ovulation, females were randomly assigned to one of four treatment groups to determine the effects of nursing behaviour on the hormonal parameters of the luteal phase: primiparous, nursing restricted (PRL; n = 9); primiparous, nursing unrestricted (PUL; n = 11); multiparous, nursing restricted (MRL; n =10); and multiparous, nursing unrestricted (MUL; n=10). Nursing restriction significantly elevated serum progesterone concentrations in PRL females compared with other mothers. Serum concentrations of oestradiol were higher in PRL, MRL and MUL mothers relative to PUL females. Again, this difference in oestradiol between PUL and MUL mothers occurred despite similarities in nursing behaviour.
These data suggest that parity/age differences in the period of lactational infertility are not due to differences in nursing behaviour but rather to an increased sensitivity to the inhibitory aspects of the suckling stimulus in adolescent primiparous mothers. Furthermore, the lack of a difference in the reproductive parameters measured between nursing restricted and unrestricted multiparous mothers suggests that these females may become refractory to the inhibitory aspects of the suckling stimulus as lactation progresses.
Journal of Endocrinology (1992) 134, 493–503
Specific binding sites for 125I-labelled epidermal growth factor in the ovine corpus luteum and human placenta
Authors: Bramley T. A. , Menzies G. S. 
Published: December 2008

ABSTRACT
Specific, high-affinity binding sites for radiolabelled mouse epidermal growth factor (mEGF) were demonstrated in homogenates and membranes of ovine corpora lutea. Subcellular fractionation on sucrose density gradients demonstrated that luteal EGF receptors were associated with fractions enriched in cell surface-membrane markers. Binding of 125I-labelled mEGF to ovine luteal EGF receptors was dependent on the pH, temperature and duration of incubation, and on the concentration of metal ions present in the incubation medium. Unlabelled mEGF and human EGF (urogastrone) competed for the binding of radiolabelled mEGF to ovine luteal homogenates at low doses (half-maximal inhibition of binding (IC50) at 2–3 nmol/l). Transforming growth factor-α also competed for mEGF-binding sites (IC50, 4–10 nmol/l), but a range of peptides, growth factors and protein hormones were ineffective at much higher concentrations. Concave Scatchard plots for 125I-labelled EGF binding and Hill coefficients of <1 for displacement radiolabelled EGF suggested negative co-operativity of binding sites, and dilution at equilibrium accelerated the rate of dissociation of 125I-labelled EGF from human placental (but not from ovine luteal) receptors.
Specific EGF-binding sites were also demonstrated in rat and rabbit placental homogenates, and in luteal homogenates of the pig. Luteal concentrations of EGF receptors appeared to be reduced significantly during early pregnancy in both the pig and sheep.
Journal of Endocrinology (1992) 135, 5–16
Epidermal growth factor concentrations in pig tissues and body fluids measured using a homologous radioimmunoassay
Authors: Vaughan T. J. , Littlewood C. J. , Pascall J. C. , Brown K. D. 
Published: December 2008

ABSTRACT
A homologous radioimmunoassay for the measurement of epidermal growth factor (EGF) levels in pig tissues and body fluids has been developed using an antiserum to recombinant porcine EGF. The assay is highly specific, showing no cross-reactivity with a variety of other polypeptides including the structurally related protein, transforming growth factor-α. Furthermore, <1% cross-reactivity was observed with mouse EGF emphasizing the necessity for homologous assays for EGF measurement. Immunoreactive EGF was present in extracts of pig kidney and pancreas (3·44 ±0·43 and 0·76 ±0·13 (s.e.m.) pmol/g wet weight respectively), but was not detected in extracts of submaxillary gland or liver. Although immunoreactive EGF was not detectable in uterine, allantoic or ovarian follicular fluids, colostrum contained EGF at biologically active concentrations (0·84±0·15 nmol/l). Immunoreactive EGF was also present in pig urine, with similar concentrations in samples from male or female animals. In addition, pig urine inhibited the binding of 125I-labelled EGF to 3T3 fibroblasts and stimulated DNA synthesis in quiescent monolayers of these cells, indicating that the immunoreactive material in urine is biologically active. Quantitative comparisons of the data presented here with that published previously indicate considerable species variation in the EGF levels of various tissues and body fluids.
Journal of Endocrinology (1992) 135, 77–83
Atrial natriuretic peptide in eel plasma, heart and brain characterized by homologous radioimmunoassay
Authors: Takei Y. , Ando K. , Kawakami M. 
Published: December 2008

ABSTRACT
A highly specific and sensitive radioimmunoassay has been developed for the measurement of eel atrial natriuretic peptide (ANP). The antiserum, raised against eel ANP-(1–27) did not cross-react with two other eel natriuretic peptides, i.e. eel ventricular natriuretic peptide and C-type natriuretic peptide (CNP), or with any mammalian ANPs, CNPs or brain natriuretic peptides so far identified. The minimal detectable amount was 0·39 fmol (0·90 pg)/tube with more than 99% confidence. Because of its high sensitivity, the radioimmunoassay makes it possible to measure eel ANP directly with only a few microlitres of plasma without extraction.
Using the radioimmunoassay we found high levels of ANP in the atrium (11 ± 2 pmol/mg wet tissue, n = 8), and much lower levels in the ventricle (56 ±8 fmol/mg, n=8) and the brain (22±1 fmol/mg, n = 8) of eels. Eel plasma contained a large amount of ANP (247 ± 66 fmol/ml, n= 8) compared with the levels reported in mammals, although atrial levels are similar between eels and mammals.
Gel-permeation chromography revealed that a major form of ANP stored in the eel atrium, ventricle and brain has a molecular mass of approximately 14 kDa but low molecular forms of about 3 kDa are predominant in eel plasma. A detailed analysis with reverse-phase high-performance liquid chromatography showed that a major molecular form circulating in eel plasma is ANP-(1–27). ANP-(1–27) was also detected in small amounts in the eel atrium, ventricle and brain.
Journal of Endocrinology (1992) 135, 325–331
Retention of normal ovarian function after hysterectomy
Authors: Metcalf M. G. , Braiden V. , Livesey J. H. 
Published: December 2008

ABSTRACT
What are the long-term effects of hysterectomy on the ovaries of normal women? Ninety-three women aged 29–44 years (median, 38 years) who had undergone hysterectomy for benign reasons 0·3–9·1 years prior to investigation, contributed urine samples twice weekly for a period of 53–149 days (median 102 days) for pregnanediol analysis. The interval between successive pregnanediol peaks and their increment over baseline were measured.
The median peak interval was 27·3 days, and 93·3% of all intervals were of 21- to 35-days duration. Of the 337 peaks observed, 96·7% met the criteria previously used to define an ovulatory cycle. These are similar to the figures reported for menstruant women of comparable age. ANOVA showed no significant effect of age or time since hysterectomy on either the interval between peaks or peak increment (P > 0·10 in all cases). The evidence suggests that the ovaries of women who have no uterus behave like those of intact women.
Journal of Endocrinology (1992) 135, 597–602
IMMUNOHISTOCHEMICAL IDENTIFICATION OF ANDROGEN RECEPTORS IN GERM CELL NEOPLASIA
Authors: Rajpert-De Meyts E. , Skakkebæk N. E. 
Published: December 2008

ABSTRACT
The highest prevalence of testicular cancer occurs in young men with high androgen activity. The presence and distribution of androgen receptors (ARs) was therefore investigated in germ cell neoplasia, using two specific monoclonal antibodies. Tissue samples from 18 patients with seminoma and/or carcinoma-in-situ (CIS) of the testis were examined. An indirect immunohistochemical method with a biotin-streptavidin-peroxidase or an alkaline phosphatase detection system was used. 45% of seminoma samples and 42% of CIS samples were AR-positive with antibody AN 1-15. The values obtained using antibody F 39.4.1 were 44 and 40% respectively. Some differences in specificity between the two antibodies were observed. Unusual granular staining of germ cells in normal testes, also present in malignant germ cells, was noted when antibody F 39.4.1 was used. The presence of AR protein immunoreactivity in neoplastic germ cells suggests that androgens may be involved in the pathogenesis of the disease.
Ontogeny and characterization of epidermal growth factor receptors on the fetal area of the sheep placenta
Authors: Lacroix M. C. , Kann G. 
Published: December 2008

ABSTRACT
Studies of the binding of 125I-labelled epidermal growth factor (EGF) to the ovine placenta were carried out on days 50, 90–100 and 140 of pregnancy. Membrane fractions were purified from the fetal area of the cotyledon. Two classes of binding sites were found. Their dissociation constants (Kd) were not significantly different for the three stages of pregnancy considered (high-affinity Kd 54–70·2 pmol/l; low-affinity Kd 12·2 to 19 nmol/l). However, the number of high-affinity binding sites on days 90–100 was significantly (P < 0·01) greater (146 ± 19 fmol/mg protein) than on either day 50 or day 140 (respectively 74·2 ± 1·26 and 56·3 ± 5·6 fmol/mg protein). Affinity cross-linking studies followed by SDS-PAGE under reducing conditions demonstrated that the major part of the EGF was specifically cross-linked to a protein of molecular weight of 150 kDa and to lesser extent to 180 kDa and 130 kDa proteins. Membranes prepared from unfrozen tissues, in the presence of sodium iodoacetate to reduce endogenous enzymatic conversion of the 180 kDa form to the 150 and 130 kDa forms, still exhibited a major EGF-binding protein of 150 kDa. The occurrence of an increased number of EGF receptors at the period of rapid cotyledonary growth which coincides with the increase in placental hormonal secretions suggests that EGF has a role in the development of the ovine placenta.
Journal of Endocrinology (1993) 136, 43–50
Follicular development and ovarian hormone secretion following passive immunization of ewes against inhibin or oestradiol
Authors: Mann G. E. , Campbell B. K. , McNeilly A. S. , Baird D. T. 
Published: December 2008

ABSTRACT
Immunization against inhibin or oestradiol causes an increase in the peripheral plasma concentration of FSH. In this study we have investigated the effect of this post-immunization rise in FSH concentration on follicular development by means of real-time ultrasonography, in ewes in which an ovary and its vascular pedicle had been autotransplanted to a site in the neck. Groups of ewes on day 10 of the luteal phase of the oestrous cycle were injected with a single 10 ml i.v. bolus of plasma from normal ewes (control; n = 4), antiserum to the 1–26 peptide fragment of the N-terminus of the α chain of porcine inhibin (n = 5) or antiserum to oestradiol-17β (n = 4). The plasma concentration of FSH was unaffected by treatment in the control group but showed a significant (P < 0·001) rise following treatment in both immunized groups (inhibin-immunized 175% over 19 h; oestradiol-immunized 138% over 22 h as a per cent of the original value). This rise in FSH concentration was accompanied by a significant (P < 0·001) rise in the total number of follicles > 2·0 mm per ovary in both immunized groups (inhibin-immunized 5·5±1·0 to 13·6± 1·4; oestradiol-immunized 4·6±0·5 to 11·5±1·0). In the oestradiol-immunized group, this rise was due to an increase (P < 0·001) in the number of small follicles (<3·5 mm) alone while, in the inhibin-immunized group, there was a rise in both the number of small follicles (P < 0·001) and the number of medium-sized follicles of 3·5–4·5 mm (1·3 ±0·5 to 3·2± 1·0, P <0·05). During the period from 12 to 20 h after immunization, when FSH concentrations were falling following the post-immunization rise, there was a significant (P <0·05) rise in the ovarian secretion rate of inhibin in the oestradiol-immunized group, and in the inhibin-immunized group the mean secretion rate of oestradiol was double that in the control group (2·7±0·5 vs 1·3 ±0·3 pmol/min, P <0·06). The temporal relationships suggest that the rise in FSH induced by passive immunization against oestradiol or inhibin stimulates the development of many antral follicles which contribute to the increased ovarian secretion of inhibin and oestradiol.
Journal of Endocrinology (1993) 136, 225–233
Transcription of prolactin gene in milk secretory cells of the rat mammary gland
Authors: Steinmetz R. W. , Grant A. L. , Malven P. V. 
Published: December 2008

ABSTRACT
In-situ hybridization and Northern blot hybridization were used to identify mRNA for pituitary prolactin in mammary tissue obtained from female rats 1 day before expected parturition, 1 day after parturition and on day 7 of lactation. Prolactin cDNA was labelled with 32P for Northern analysis and with digoxigenin for in-situ hybridization. Total and poly(A)+ RNA from pituitary, mammary and control (fat and kidney) tissues were analysed by agarose gel electrophoresis with transfer to nitrocellulose and hybridization to a cDNA for rat prolactin. Although present in much smaller amounts than the 1·0 kb transcript in pituitary RNA homogenates, mammary RNA homogenates from all three stages contained mRNA of approximately 1·0 kb which hybridized with the prolactin probe. Similar analyses of fat and kidney failed to reveal any hybridization at the 1·0 kb size. When tissue sections were hybridized to the cDNA probe, specific hybridization was observed in the milk secretory cells of the mammary alveoli and the lactotroph cells of the anterior pituitary, but not in liver cells or in RNase-treated sections of mammary tissue. In summary, these results demonstrate that milk secretory cells of the rat mammary gland transcribe the gene for prolactin, and they raise the possibility that a primary target tissue for blood-borne prolactin may also synthesize prolactin.
Journal of Endocrinology (1993) 136, 271–276