bluuebunny/crossref_metadata_2025_split huggingface dataset:
The regulation by thyroid hormones and androgen of epidermal growth factor synthesis in the submandibular gland and its plasma concentrations in mice
Authors: Kasayama S. , Yoshimura M. , Oka T. 
Published: December 2008

ABSTRACT
The effects of androgen and thyroid hormones on epidermal growth factor (EGF) synthesis in the submandibular gland and on plasma EGF concentrations in mice were examined. Testosterone propionate was administered alone or in combination with l-thyroxine (T4) to female mice for 2 weeks. The submandibular EGF concentrations were increased by the administration of testosterone propionate in a dose-dependent fashion; the maximal increase, 20-fold, being produced by a dose of 2 mg every other day. The EGF levels were increased sevenfold by T4, which also enhanced the stimulatory effect of suboptimal doses of testosterone propionate. Cyproterone acetate, an anti-androgen, inhibited the testosterone propionate-induced increase, but not the T4-induced increase. Plasma EGF concentrations were raised by testosterone propionate but not by T4. Both hormones stimulated the accumulation of 4·7 kb preproEGF mRNA in the submandibular gland, which occurred almost in a parallel manner with the increase in submandibular EGF concentrations. These results suggest that EGF synthesis in the submandibular gland is regulated by alterations in the level of its mRNA by thyroid hormones and androgen, and that the rise in plasma EGF concentrations is under the influence of androgen but not of thyroid hormones.
Journal of Endocrinology (1989) 121, 269–275
A new way to induce oestrogen-deficiency osteopaenia in the rat: comparison of the effects of surgical ovariectomy and administration of the LHRH agonist buserelin on bone resorption and composition
Authors: Goulding A. , Gold E. 
Published: December 2008

ABSTRACT
Prolonged administration of LHRH agonist suppresses pituitary gonadotrophin secretion, thereby lowering blood oestrogen. This study was undertaken to compare the osteopaenic effects of bilateral ovariectomy and chronic administration of the LHRH agonist, buserelin, in the rat. Four groups of animals which had their skeletons labelled with 45Ca were studied for 4 weeks. Group 1 underwent a sham-ovariectomy, group 2 were surgically ovariectomized, group 3 were given buserelin by daily s.c. injection and group 4 were given a continuous infusion of buserelin by osmotic minipump. Plasma concentrations of oestradiol were measured weekly. Bone resorption was assessed by measuring the urinary excretion of 45Ca and hydroxyproline and determining bone 45Ca content.
Ovariectomy and buserelin treatments lowered blood oestradiol, increased biochemical indices of bone resorption and decreased femur and total body calcium and 45Ca values. The degree of oesteopaenia elicited by ovariectomy and buserelin treatment was similar. Bone responses to s.c. buserelin and to continuous buserelin infusion were alike. We attribute evidence of increases in bone resorption and induction of osteopaenia with buserelin treatment to hypo-oestrogenism.
We have shown for the first time by bone analysis that buserelin induces osteopaenia as effectively as bilateral ovariectomy. This appears to be the first demonstration in the rat that long-term administration of LHRH agonist influences bone. Administration of buserelin provides a new way of inducing oestrogen-deficiency osteopaenia in the rat without removing the ovaries.
Journal of Endocrinology (1989) 121, 293–298
Effect of level of food intake of ewes on the secretion of LH and FSH and on the pituitary response to gonadotrophin-releasing hormone in ovariectomized ewes
Authors: Rhind S. M. , Martin G. B. , McMillen S. , Tsonis C. G. , McNeilly A. S. 
Published: December 2008

ABSTRACT
The effect of level of food intake on LH and FSH profiles and pituitary sensitivity to gonadotrophin-releasing hormone (GnRH) was investigated in two groups of 12 ovariectomized ewes. Ewes with a high intake (group H) had a mean daily intake (± s.e.m.) of 1·99 ± 0·075 kg dry matter (DM)/head per day while ewes with a moderate intake (group M) consumed a mean of 1·02 ± 0·021 kg DM/head per day. Ovaries were surgically removed from six ewes of each group on day 11 of the luteal phase and from the remainder 30 h after an injection of 100 μg prostaglandin analogue given on day 11 to induce luteolysis. During both the luteal phase and the follicular phase, mean LH and FSH concentrations and LH pulse frequencies and amplitudes were unaffected by the level of intake but mean plasma prolactin concentrations were higher (P < 0·05) in group H than in group M ewes in the follicular phase. Mean LH and FSH concentrations at day 2 after ovariectomy were unaffected by treatment while mean prolactin concentrations were higher (P < 0·05) in group H than in group M ewes. At day 7 after ovariectomy, mean LH and FSH concentrations were lower (P < 0·05) in group H than in group M ewes although mean LH pulse frequencies and pulse amplitudes were not significantly affected by the level of intake at either time.
The level of food intake and the stage of the oestrous cycle at the time of ovariectomy did not affect the amount of LH released in response to a bolus injection of GnRH (10 μg, i.v.) but the FSH response was significantly (P < 0·05) greater in group M than in group H ewes.
It is concluded that the pituitary glands of ovariectomized ewes with moderate levels of intake are more responsive to GnRH than those of ewes with a high intake and that hypothalamic activity and GnRH secretion are not affected by the level of food intake.
Journal of Endocrinology (1989) 121, 325–330
Pulsatile growth hormone, insulin-like growth factors and antler development in red deer (Cervus elaphus scoticus) stags
Authors: Suttie J. M. , Fennessy P. F. , Corson I. D. , Laas F. J. , Crosbie S. F. , Butler J. H. , Gluckman P. D. 
Published: December 2008

ABSTRACT
Plasma samples taken every 30 min over a 26-h period each month from six 4- to 15-month-old red deer stags were analysed for GH. In addition, two samples taken at 10.00 and 22.00 h were analysed for insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II). A concentrate diet was available ad libitum. Food intake, body weight and antler status were recorded. Concentrations of GH were analysed using the PULSAR peak detection routine. Secretion of GH was pulsatile in every month of sampling, but the pattern of pulsatility differed seasonally. During the autumn and early winter (April–June in the Southern hemisphere) GH pulses were frequent and of low amplitude. In contrast, GH pulses in spring (August–September) were of high amplitude and high frequency resulting in a high mean level of GH circulating in the plasma.
In early summer (November) the GH pulse amplitude was much lower and pulse frequency fell. There was a rise in GH pulse frequency not accompanied by an increase in GH pulse amplitude in summer (December–January). GH pulse amplitude seemed to be the main determinant of mean GH plasma level. Secretion of IGF-I was raised 1 month after peak monthly mean GH secretion. There was little consistent relationship between concentrations of IGF-II and mean daily GH. Concentrations of GH correlated positively and significantly with liveweight gain and antler growth rate with a delay of 1 month. Significantly positive correlations between concentrations of IGF-I, liveweight gain and antler growth rate were observed. It is considered that the spring and summer (September–December) seasonal acceleration of liveweight gain and antler development in stags could be a consequence of high winter/early spring (August–September) GH pulse frequency and amplitude resulting in increased concentrations of IGF-I, particularly in October.
Journal of Endocrinology (1989) 121, 351–360
Effects of amiodarone on 5′-deiodination of thyroxine to tri-iodothyronine in rat myocardium
Authors: Ceppi J. A. , Zaninovich A. A. 
Published: December 2008

ABSTRACT
The present work studied the effects of amiodarone (AMD) and iopanoic acid (IA) on the conversion of thyroxine (T4) to tri-iodothyronine (T3) by rat myocardium. In vivo: male Wistar rats weighing 200–250 g were injected i.p. with AMD (2·5 mg/100 g body weight per day for 12 days) or IA (5 mg/100 g body weight every 12 h for 72 h). Hearts were then removed and processed as in the in-vitro studies. In vitro: hearts were homogenized in Krebs–Ringer phosphate buffer (pH 7·4) and AMD (0·1 mmol/l) or IA (10 mmol/l) plus dithiothreitol (8 mmol/l) and 0·01 μCi [125I]T4 or [125I]T3 were added. After incubation for 2 h at 37 °C, radioactive compounds were identified by paper chromatography. Both AMD and IA given in vivo blocked T4 to T3 conversion significantly (P<0·005). When added in vitro, AMD failed to inhibit T4 deiodination to T3 whereas IA induced a significant (P<0·005) decrease in T3 generation. Deiodination of [125I]T3 by heart homogenates was not altered by AMD or IA. While the expected increase in circulating T4 (P< 0·001) and decrease in T3 (P< 0·001) did occur after AMD or IA treatment, plasma TSH in AMD-treated rats was decreased (P<0·001), while in IA-treated animals it was increased (P< 0·001), thus indicating that AMD did not inhibit pituitary type-II 5′-monodeiodinase.
In summary, these data suggest that the hypometabolism induced by AMD in rat myocardium through a decrease in the supply of T3 is not responsible for the anti-arrhythmic activity of this drug since IA, which is not an anti-arrhythmic compound, elicited the same effect on cardiac T3. It follows that inhibition of 5′-deiodinase and the anti-arrhythmic activity of AMD are independent properties.
Journal of Endocrinology (1989) 121, 431–434
Effects of islet hormones on insulin secretion from cloned B cell lines, HIT-T15 and RINm5F
Authors: Lambert D. G. , Atkins T. W. 
Published: December 2008

ABSTRACT
The effects of the islet cell hormones glucagon, somatostatin-28 and pancreatic polypeptide on insulin secretion from cultured cloned pancreatic B cells (HIT-T15 and RINm5F) have been investigated. Glucagon stimulates the secretion of insulin from HIT-T15 cells in the absence and presence of glucose and from RINm5F cells in the absence and presence of glyceraldehyde. HIT-T15 cells were more sensitive to the stimulatory effect of glucagon than RINm5F cells. Somatostatin-28 and pancreatic polypeptide, both alone and in combination, reduced glucose- and glucagon-stimulated insulin release from HIT-T15 cells and glyceraldehyde- and glucagon-stimulated insulin release from RINm5F cells. HIT-T15 cells were more sensitive to the inhibitory actions of somatostatin-28 and pancreatic polypeptide than RINm5F cells. This study supports the hypothesis that insulin release from normal B cells may be modified by the paracrine activity of islet hormones, glucagon, somatostatin and pancreatic polypeptide and probably occurs before any fine tuning imposed by subsequently released insulin.
Journal of Endocrinology (1989) 121, 479–485
Peripheral blood levels of immunoreactive inhibin during pseudopregnancy, pregnancy and lactation in the rat
Authors: Taya K. , Komura H. , Watanabe G. , Sasamoto S. 
Published: December 2008

ABSTRACT
Concentrations of inhibin in peripheral blood were determined by radioimmunoassay in pseudopregnant, pregnant and lactating rats and correlated with the status of follicular development, luteal function in the ovaries and placental function. In pseudopregnant rats, plasma concentrations of inhibin remained relatively high from days 2 to 12 of pseudopregnancy and no significant changes occurred throughout pseudopregnancy. In pregnant rats, a marked decline in plasma concentrations of inhibin occurred between days 6 and 14 followed by an abrupt increase on days 20 and 21. In lactating rats, plasma concentrations of inhibin were consistently lower in dams nursing eight pups than in dams nursing two pups. Plasma concentrations of inhibin remained low during the early stages of lactation followed by a significant increase during the late stages in dams nursing eight pups. These changes in inhibin during the period of lactation correlated with those of plasma concentrations of LH, but not with those of oestradiol-17β, testosterone and progesterone. Throughout pseudopregnancy, pregnancy and lactation, on the other hand, plasma concentrations of FSH were within the range of dioestrous levels.
These findings indicate that concentrations of inhibin in peripheral plasma vary with the number of healthy antral follicles and no positive correlation was observed with luteal function during the luteal phase in rats. The results also suggest that inhibin is a more direct index of follicular development than oestradiol-17β in rats.
Journal of Endocrinology (1989) 121, 545–552
Nocturnal changes in serum melatonin during female puberty in rhesus monkeys: a longitudinal study
Authors: Wilson M. E. , Gordon T. P. 
Published: December 2008

ABSTRACT
Diurnal concentrations of serum melatonin were determined longitudinally in female rhesus monkeys throughout sexual maturation to ascertain how levels varied with advancing age and reproductive onset. Females were housed either in outdoor enclosures (n = 8) exposed to ambient environmental conditions, or indoors (n = 4) under a photoperiod of 12 h light: 12 h darkness and fixed temperature of 20–23 °C. Animals were studied from immaturity (15 months) through first ovulation and were additionally compared with fully adult female rhesus monkeys (n = 5) studied during the annual breeding season. The diurnal melatonin pattern was described for the developing females in the summer, autumn and winter in 3 successive years from samples collected at 10.00, 18.00, 22.00, 02.00, 06.00 and 10.00 h.
Nocturnal levels of melatonin declined significantly during development in both indoor- and outdoor-housed females with a progressive decrease up to 33 months of age. Daytime values were consistently low but exhibited a slight decline also with age. Nocturnal values in all months sampled fell significantly with greater decreases occurring at the earliest ages. Furthermore, superimposed upon this developmental change, animals housed outdoors responded to seasonal changes in photoperiod with diurnal increases in melatonin occurring after sunset. The females in the present study exhibited first ovulation at two distinct ages: 32–37 months ('early', n = 6) and 41–45 months ('later', n=5). One female did not ovulate within the study period. Although nocturnal levels of serum melatonin were similar between the two groups up to 29 months of age, a post-hoc analysis revealed that concentrations were significantly lower by 34 months of age for the early group, a time coincident with first ovulation. Nocturnal levels of melatonin remained high, relative to the early group, in the later ovulating females until 43 months of age, coincident with first ovulation for these animals. The diurnal pattern of serum melatonin at first ovulation, regardless of chronological age, was similar to that observed during the ovulatory season for adult female rhesus monkeys.
These data suggest that nocturnal melatonin concentrations decline with advancing chronological age in prepubertal female rhesus monkeys. Furthermore, the timing of sexual maturation was inversely related to nocturnal melatonin. Whether this change in melatonin is causally related to reproductive onset or, rather, is a consequence of other factors regulating the occurrence of first ovulation remains to be determined. Furthermore, the observation that the melatonin rhythm in outdoor-housed females follows the prevailing photoperiod permits the hypothesis that this rhythm may mediate any photoperiodic effect on the seasonal occurrence of first ovulation characteristic of rhesus monkeys housed outdoors.
Journal of Endocrinology (1989) 121, 553–562
Thyrotrophin (TSH)-binding proteins in bacteria and their cross-reaction with autoantibodies against the human TSH receptor
Authors: Byfield P. G. H. , Davies S. C. , Copping S. , Barclay F. E. , Borriello S. P. 
Published: December 2008

ABSTRACT
A screen of a range of bacteria normally found in gut flora identified eight with the ability to bind TSH specifically. These included the previously reported Yersinia enterocolitica, Gram-positive, Gramnegative, pathogenic and commensal organisms. Eleven preparations of TSH-receptor autoantibodies strongly able to displace 125I-labelled TSH from the mammalian TSH receptor differed in their ability to displace the tracer from binding to bacterial extracts. None could displace the tracer from E. coli 06–1, four displaced 125I-labelled TSH from E. coli V21/1 and five displaced the tracer from Y. enterocolitica. Of those immunoglobulin preparations which did react with the bacterial protein, their apparent potency compared with that of TSH in displacing tracer from bacterial binders was an order of magnitude greater than with the mammalian receptor. This is consistent with the autoantibodies having a relatively better fit with the bacterial antigen than with the receptor when compared with TSH. The bacterial-binding activity and mammalian receptor-binding activities in each of two samples co-chromatographed on a Remazol yellow GGL–Sepharose affinity column strongly indicated that the same immunoglobulin species reacts with both antigens. These results are consistent with the proposal that a bacterial protein is the primary immunogen for the TSH-receptor antibodies in at least some patients with Graves' disease.
Journal of Endocrinology (1989) 121, 571–577
Controls of corticotrophin-releasing factor output by hypothalamic tissue from fetal sheep in vitro
Authors: Brooks A. N. , Power L. A. , Jones S. A. , Yang K. P. , Challis J. R. G. 
Published: December 2008

ABSTRACT
Corticotrophin-releasing factor (CRF) is thought to be an important physiological regulator of the pituitary-adrenal axis in fetal sheep and, as such, plays a fundamental role in the initiation of parturition in this species. However, little is known of the controls of CRF secretion from the fetal hypothalamus.
We looked for the presence of CRF in fetal hypothalami, and examined whether the hypothalamic CRF concentration or molecular species changed in relation to gestational age. We established an in-vitro perifusion system to examine the release of CRF from perifused hypothalami taken from fetuses at day 100 and day 140 of pregnancy, under basal conditions and in response to potassium depolarization and/or dexamethasone administration.
Immunoreactive CRF was present in fetal hypothalami as early as day 100 (2·42 ± 0·99 (s.e.m.) μg/g protein, n = 9) and in similar concentrations at day 140 (2·31 ± 0·69 μg/g protein, n = 9). There was a significant (P < 0·05) increase in hypothalamic CRF content to 14·79 ± 4·09 μg/g protein (n = 16) between day 122 and day 135 of gestation. Using Sephadex G-75 chromatography, hypothalamic extracts at day 100, days 122–135 and day 140 eluted with a single peak of immunoreactivity which corresponded to synthetic ovine CRF(1–41).
The basal release of CRF from perifused hypothalami at day 140 (76·6 ± 10·4 pg/fraction, n = 8) was significantly (P < 0·05) greater than at day 100 (50·1 ± 10·2 pg/fraction, n = 11). Dexamethasone significantly inhibited basal CRF release at day 140 of gestation but not at day 100. Potassium depolarization caused a rapid release of CRF in all cases, a response which was independent of gestational age or treatment with dexamethasone.
We conclude that the fetal hypothalamus contains immunoreactive CRF as early as day 100 of gestation and that this material may be released when perifused in vitro under basal conditions and in response to a depolarizing agent. The basal release of CRF from perifused hypothalami of day-140 fetuses was greater than at day 100 and was inhibited by dexamethasone, suggesting maturation of negative feedback control of CRF output between days 100 and 140. Since dexamethasone had no effect on potassium-stimulated release of CRF, we suggest that its effects are at sites other than the hypothalamic CRF nerve terminals.
Journal of Endocrinology (1989) 122, 15–22
Glucocorticoid regulation of human growth hormone expression in transgenic mice and transiently transfected cells
Authors: Selden R. F , Yun J. S. , Moore D. D. , Rowe M. E. , Malia M. A. , Wagner T. E. , Goodman H. M. 
Published: December 2008

ABSTRACT
A mouse metallothionein-I/human growth hormone fusion gene was microinjected into fertilized mouse eggs, the embryos were implanted into pseudopregnant foster mothers, and the offspring analysed. Five of twenty-six mice born after one series of injections contained from one to eight copies of the fusion gene stably integrated into their genomes and had human growth hormone in their serum. When several of these transgenic mice and transgenic offspring were treated with glucocorticoids, serum growth hormone levels were elevated from 1·5- to 6·3-fold. A fourfold induction in fusion gene mRNA in the liver of one of the five mice was also observed after treatment with glucocorticoids. When the fusion gene was transiently transfected into mouse L cells, dexamethasone caused a three- to fourfold induction of fusion gene mRNA and secreted human growth hormone. A deletion analysis of regulatory elements required for inducibility in L cells shows that DNA sequences responsible for the observed inductions are located within the transcribed region of the human growth hormone gene. However, a previously described glucocorticoid receptor binding site in the first intron of the gene is not required for response to the hormone.
Journal of Endocrinology (1989) 122, 49–60
The oestrogen-induced surge of LH requires a 'signal' pattern of gonadotrophin-releasing hormone input to the pituitary gland in the ewe
Authors: Clarke I. J. , Cummins J. T. , Jenkin M. , Phillips D. J. 
Published: December 2008

ABSTRACT
Two experiments were conducted with ovariectomized and hypothalamo-pituitary disconnected (HPD) ewes to ascertain the pattern of inputs, to the pituitary gland, of gonadotrophin-releasing hormone (GnRH) necessary for the full expression of an oestrogen-induced LH surge. The standard GnRH replacement to these sheep was to give pulses of 250 ng (i.v.) every 2 h; at the onset of experimentation, pulses were given hourly. In experiment 1, groups of sheep (n = 7) were given an i.m. injection of 50 μg oestradiol benzoate, and after 10 h the GnRH pulse frequency or pulse amplitude was doubled. Monitoring of plasma LH concentrations showed that a doubling of pulse frequency produced a marked increase in baseline values, whereas a doubling of amplitude had little effect on the LH response. In a second experiment, ovariectomized HPD sheep that had received hourly pulses of GnRH for 16 h after an i.m. injection of oil or 50 μg oestradiol benzoate were given either a 'bolus' (2·25 μg GnRH) or a 'volley' (500 ng GnRH pulses 10 min apart for 30 min, plus a 500 ng pulse 15 min later). Both groups then received GnRH pulses (250 ng) every 30 min for the next 13 h. Oestrogen enhanced the LH responses to the GnRH treatments, and the amount of LH released was similar in ovariectomized HPD ewes given oestrogen plus bolus or volley GnRH treatments and ovariectomized hypothalamopituitary intact ewes given oestrogen.
These results suggest that the oestrogen-induced LH surge is initiated by a 'signal' pattern of GnRH secretion from the hypothalamus.
Journal of Endocrinology (1989) 122, 127–134