bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in gonadotrophin secretion during childhood and puberty
Authors: Bridges N A , Matthews D R , Hindmarsh P C , Brook C G D
Published: December 2008

The changes in gonadotrophin secretion in childhood and puberty involve changes in the pulsatile pattern as well as mean concentration. We have examined pulsatile secretion using 24-h LH profiles in 78 children aged 4·2–15·6 years and six adult men. The profiles were analysed by a method which gives an estimate of peak and baseline levels and by spectral analysis. Prepubertal children were divided into groups by age and pubertal children by pubertal stage.

Baseline LH levels in children aged 4·2–6·9 years were higher than in those aged 7·1–9·8 years. Pulse frequency in both groups was slow (periodicities 140–200 min). In the oldest prepubertal group there was an increase in peak levels with increased spectral power at periodicities of 100–120 min. Pulse frequency did not change in puberty (periodicity 120–160 min). Girls demonstrated an increase in both peak and baseline LH concentrations in early puberty. Boys had an increase in only peak levels in early puberty; there was no increase in baseline concentrations until a testicular volume of 10 ml was attained.

In conclusion, these data show that LH levels do not reach a nadir until 8 years of age. We have detected a sex difference in the pattern of LH secretion seen in early puberty, and this mirrors clinical findings. The mature pattern attained by the end of puberty in both sexes is probably important for fertility.

Journal of Endocrinology (1994) 141, 169–176
The appearance and activity of tissue thyroxine 5′- and 5-monodeiodinase during ontogenesis in the fetal pig
Authors: Ślebodziński A B , Brzezińska-Ślebodzińska E
Published: December 2008

The ontogeny of the fetal monodeiodinase systems, during the period before the onset of thyroid activity until birth, has been described only in the rat, rabbit and chick. We have studied 5′- and 5-monodeiodinase activities in the liver, kidney and placenta of pig fetuses, from day 32 of gestation up to birth, and on days 1, 3, 7 and 14 after birth. Fetuses (123) from 15 litters, 32 newborn piglets, 15 sows (mothers) and 10 non-pregnant pigs were used. The relationships between monodeiodinase activities, thyroxine (T4), tri-iodothyronine (T3) and reverse triiodothyronine (rT3) blood serum concentrations and sulphydryl groups (total (T-SH) and non-protein (NP-SH)), were measured.

5′-Monodeiodinase activity (5′-MD type I; converting T4 to T3) and 5-monodeiodinase (5-MD; converting T4 to rT3) were detectable in the liver at the onset of thyroid hormone biosynthesis, and before that time (day 32 of gestation) in the placenta. Liver 5′-MD activity was very low between days 32 and 84 of gestation, and then increased rapidly at about day 93, reaching a maximal value 2 days before term. Activity in the liver (but not in the kidney) was higher than that in maternal, newborn and non-pregnant adult tissue. The increase in NP-SH groups in the liver and kidney and T-SH groups in the placenta during the last 5 days of gestation coincided with the increase in 5′-MD activity. The 5-MD activity of the liver was generally five to ten times lower than that of 5′-MD, being highest on days 65–76 and 65–84 in the kidney and placenta respectively.

Serum T4 concentrations paralleled the steady increase in T4- to T3-converting activity in the kidney and liver, but not in the placenta. Two weeks before birth, fetal T3 concentrations exceeded those of rT3 by a factor of 1·5 or more, indicating that T4 metabolism in the pig is dominated by the activity of 5′-MD. This pattern is different from that in prenatal humans, rats or sheep in which rT3 is the primary circulating T4 metabolite.

Journal of Endocrinology (1994) 141, 243–249
Functional heterogeneity with respect to oestrogen treatment in prolactin cell subpopulations separated by Percoll gradient centrifugation
Authors: Velkeniers B , Kazemzadeh M , Vanhaelst L , Hooghe-Peters E L
Published: December 2008

The effects of oestradiol on prolactin gene expression were studied by quantitative in situ hybridization histochemistry in different prolactin pituitary cell (sub)populations, which had been obtained by separation on a discontinuous Percoll gradient. When cells were incubated in vitro in the presence of oestradiol (10−8 m) for a period of 4, 24, 48 and 72 h, there was an increase in the amount of prolactin mRNA, from 24 h on, only in high-density prolactin cells and lactotrophs of the total cell suspension. In contrast, the amount of prolactin mRNA in lactotrophs of low density did not change upon treatment with oestradiol. Pharmacological treatment with 50 μg oestradiol/day (s.c.) of random cycling female rats in vivo for 14 days increased the total number of prolactin gene-expressing cells and more lactotrophs were recovered at high density after Percoll gradient centrifugation. These results suggest a preferential stimulatory effect of oestradiol on prolactin gene transcription on a subpopulation of lactotrophs. Changes observed in prolactin cell layers after oestradiol treatment in vivo may represent a preferential effect in situ on a particular mammotroph cell subpopulation.

Journal of Endocrinology (1994) 141, 251–258
Blood sampling procedures influence serum calcitonin concentrations in rats
Authors: Feinstein R E , Bucht E , Grimelius L , Iwarsson K , Rönnbäck C , Selking Ö , Sjöstedt U , Sjöberg H -E
Published: December 2008

The aim of this study was to determine whether serum calcitonin (S–CT) in rats is influenced by the method of taking blood samples. Sampling during halothane anaesthesia, after repeated administration of anaesthesia after a 14-day interval, and sampling without the use of anaesthetics (i.e. after the rats were made unconscious by stunning), resulted in different S–CT values (P≤0·001), whereas Ca2+ levels were not affected. In thyroidectomized rats, the S–CT values after stunning were not significantly different whereas those in sham-operated rats were different (P≤0·01). The possibility that anaesthesia may suppress stunning-induced changes in S–CT was explored in three other groups of rats subjected to halothane anaesthesia, stunning and stunning under halothane anaesthesia respectively. Although the S–CT level was highest after stunning and lowest in halothane-anaesthetized rats (P≤0·001), anaesthesia did not suppress the effect of stunning on S–CT. In conclusion the effect of sampling procedures must be considered in studies on the levels of S–CT in rats.

Journal of Endocrinology (1994) 141, 267–270
Intrathyroidal cytokine gene expression profiles in autoimmune thyroiditis
Authors: Paschke R , Schuppert F , Taton M , Velu T
Published: December 2008

Cytokines are thought to mediate the initiation and perpetuation of autoimmune thyroiditis. However, this concept is mainly based on in vitro findings and to date only interleukin (IL)-6 and interferon-γ (IFN-γ) have been detected in Graves' disease in vivo. The cytokine pattern produced by T-helper (Th) cells has important regulatory effects on the nature of the immune response. We therefore determined these cytokine mRNAs in Graves' disease and Hashimoto's thyroiditis.

RNA was extracted by cesium chloride gradient centrifugation from the thyroid tissue of 12 patients undergoing thyroid resection for Graves' disease and from two patients being treated for Hashimoto's thyroiditis. Two patients with parathyroid adenomas and one patient with a goiter were used as controls. RNA was also extracted from normal human thyroid epithelial cells in primary culture. The cDNAs were prepared by reverse transcription and amplified for IL-2, -4, -5, -6 and -10 and IFN-γ by polymerase chain reaction.

All the cytokine mRNAs were detected in the Hashimoto's thyroid glands in large quantities. Six of the 12 Graves' disease thyroid glands showed, when compared with controls, an increased accumulation of transcripts for: IFN-γ, IL-2, -4 and -10 or IL-2, -4 and IFN-γ or IL-2 and IFN-γ or IFN-γ alone, each in one case or IL-2 alone in two cases. These cytokine profiles were not representative of a Th1 or Th2 phenotype. Increased amounts of cytokine mRNA in thyroid glands from Graves' disease patients were mostly associated with high microsomal antibody titres and/or prominent intrathyroidal lymphocytic infiltration. IL-6 and/or IL-10 mRNAs were detectable in all Graves' disease thyroid glands and in control thyroid tissue. IL-10 mRNA was not detectable in normal human thyroid epithelial cells in primary culture.

Graves' disease and Hashimoto's thyroiditis clearly differ with respect to the number of positive intrathyroidal cytokine mRNAs and their levels. The different cytokine patterns in Graves' disease and in Hashimoto's thyroiditis could reflect the clinical spectrum of autoimmune thyroiditis which is characterized by thyroid tissue destruction and/or thyroid autoantibody production. These data suggest that the course of autoimmune thyroiditis is regulated by the interplay of several cytokines.

Journal of Endocrinology (1994) 141, 309–315
Functional expression of the recombinant human FSH receptor
Authors: Minegishi T , Igarashi S , Nakamura K , Nakamura M , Tano M , Shinozaki H , Miyamoto K , Ibuki Y
Published: December 2008

The functional capacity of the recombinant human FSH (hFSH) receptor was tested on the basis of gonadotrophin stimulation of cyclic AMP (cAMP) production by transient transfections of 293 cells and stable transfections of Chinese hamster ovary (CHO) cells. A CHO cell line expressed with the hFSH receptor cDNA covering the entire amino acid coding region revealed the presence of FSH binding site (Kd 6·2 × 10−10 m) on the plasma membrane. Treatment of transfected cells with hFSH induced dose-dependent increases in intracellular cAMP production. These results indicate that the hFSH receptor functionally couples with endogenous adenylyl cyclase. Although rat FSH also induced dose-dependent increases in cAMP production, bovine FSH was effective only at high doses and human chorionic gonadotropin did not alter cAMP levels compared with control values.

Northern blot analysis with a cRNA probe derived from hFSH receptor cDNA indicated the presence of two common FSH receptor mRNA transcripts (2·4 and 4·1 kb) in RNA prepared from a human ovary and transfected cell lines.

Preincubation of CHO cells expressing a functional hFSH receptor (CHO-FSHR) with FSH for 16 h decreased the subsequent cAMP production resulting from a 30-min pulse of FSH stimulation. These results indicate that desensitization of the adenylyl cyclase response to FSH stimulation occurs in CHO-FSHR cells. This cell line therefore provides a tool with which to pursue detailed studies on the molecular basis of FSH-induced desensitization.

Journal of Endocrinology (1994) 141, 369–375
Insulin-like growth factor-binding protein-3 expression and secretion by cultures of human prostate epithelial cells and stromal fibroblasts
Authors: Birnbaum R S , Ware J L , Plymate S R
Published: December 2008

Prostate-specific antigen (PSA) was recently shown to be an insulin-like growth factor-binding protein (IGFBP)-3 protease. However, only IGFBPs-2 and -4 have been identified in conditioned medium of prostate epithelial cells. Using cultures of human prostate epithelial and stromal fibroblastic cells, we examined conditioned medium and cell extracts for evidence of IGFBP-3 expression and secretion. Western ligand blotting of conditioned medium from epithelial or stromal cultures revealed the presence of IGFBPs in the molecular weight range 36–48 kDa, suggestive of IGFBP-3. Western immunoblots of these media confirmed the presence of IGFBP-3. Northern analyses of extracts of both stromal and epithelial cells showed a 2·5 kb band, the size of IGFBP-3 mRNA. We conclude that prostate cells express IGFBP-3 and that local proteolysis by PSA could modify this binding protein's actions in the prostate.

Journal of Endocrinology (1994) 141, 535–540
Negative correlation between plasma GHRH values and growth velocity in short prepubertal children
Authors: Evain-Brion D , Porquet D , Fjellestad-Paulsen A , Donnadieu M , Noel M , Leger J , Simon D , Czernichow P
Published: December 2008

Numerous data suggest that impaired growth hormone secretion in short children is usually related to abnormal regulation of the hormone at the hypothalamic level. In order to improve our understanding of neurohypothalamic dysfunction in short children, we measured basal and peak (after l–dopa stimulation) plasma growth hormone-releasing hormone levels in 43 prepubertal children. Among them, in 23 children suspected of having hypothalamic growth hormone dysregulation, growth hormone-releasing hormone values were significantly higher than those observed in normal short stature children (n=20), no longer correlated with peak growth hormone following l–dopa, and negatively correlated with growth velocity. This suggests that a predominant inhibitor of growth hormone secretion, such as an increase in somatostatin tone, might be prevalent in a large number of children with partial growth hormone deficiency and suspected hypothalamic growth hormone dysregulation.

Journal of Endocrinology (1994) 141, 541–546
Binding of 1,25-dihydroxyvitamin D3 receptors to the 5′-flanking region of the bovine parathyroid hormone gene
Authors: Hawa N S , O'Riordan J L H , Farrow S M
Published: December 2008

To further define the binding site for receptors for 1,25(OH)2D3 (VDR) in the bovine PTH gene and to study the interactions of transcription factors with VDR, Southwestern and gel shift assays were used. Data from the former indicated binding of VDR to DNA fragments spanning the regions −451 to −348 bp and −668 to −452 bp. Studies using gel shift assays confirmed binding to the −451 to −348 bp fragment and specificity was shown by using excess concentrations of unlabelled −451 to −348 bp fragment to compete for binding, whereas excess unlabelled −347 to +50 bp did not compete. Binding was also observed with the −668 to −452 bp fragment but excess concentrations of unlabelled −668 to −452 or −451 to −348 bp fragments did not compete for binding to radiolabelled fragments. These data indicate the presence of two binding domains within this region; the upstream element having a lower affinity for VDR than the downstream element. In addition, there was no interaction between VDR and consensus sequences for AP1, AP2, AP3 and SP1. The putative vitamin D3 response element (VDRE) contains two similar hexameric steroid response element-like half-sites placed as AGGTCA-related direct repeats. The upstream repeat is at −461 to −456 bp and the downstream element is at −449 to −444 bp. The presence of these half-sites is consistent with our experimental data in which cleavage with SspI at −452 bp resulted in two DNA fragments which bound VDR.

Journal of Endocrinology (1994) 142, 53–60
Intermittent retinoie acid in combination with continuous oestradiol-17β increases cancellous bone volume in osteopaenic ovariectomized rats
Authors: Tobias J H , Gallagher A , Chambers T J
Published: December 2008

Although short-term administration of oestradiol-17β (OE2) stimulates cancellous bone formation in the rat, this is replaced by a tendency to suppression after prolonged treatment. Hence, in rats rendered osteopaenic by ovariectomy, OE2 administration fails either to induce a sustained increase in bone formation or to restore bone volume. A possible explanation for this failure is that OE2 also inhibits bone resorption, secondarily suppressing bone formation through coupling mechanisms. We therefore investigated whether the effects of OE2 treatment might be modified by intermittently stimulating bone resorption with retinoic acid (120mg/kg daily) for 4 out of every 20 days. We found, in a preliminary experiment using intact animals, that intermittent retinoic acid reduced cancellous bone volume, consistent with previously documented stimulation of bone resorption by retinoic acid. Rats were then rendered osteopaenic by ovariectomy, and given vehicle, retinoic acid and/or OE2. We found that animals treated with intermittent retinoic acid and OE2 showed a substantial increase in cancellous bone volume compared with ovariectomized animals treated with vehicle, retinoic acid alone or OE2 alone. Therefore, intermittent retinoic acid appears to cause a net increase in bone formation over resorption when given to ovariectomized animals in conjunction with OE2. We conclude that the effects of OE2 on cancellous bone are modified by intermittent treatment with retinoic acid, resulting in a substantial increase in bone volume.

Journal of Endocrinology (1994) 142, 61–67
The effects of pyroglutamylglutamylprolineamide, a peptide related to thyrotrophin-releasing hormone, on rat anterior pituitary cells in culture
Authors: Ashworth R J , Ham J , Cockle S M
Published: December 2008

Pyroglutamylglutamylprolineamide, which was first discovered in mammalian prostate, differs from thyrotrophin-releasing hormone (TRH) by substitution of glutamic acid for histidine at position two of the tripeptide. Recently, the newly discovered peptide has been identified in substantial concentrations in the rat anterior pituitary gland and, in this study, we have investigated the effects of the peptide on rat anterior pituitary cells in culture. GH3 cells were chosen to examine the possible effects of the new peptide, particularly in relation to its effects on the TRH receptor. This cell-type was deficient, in comparison with normal rat pituitary cells, in the new TRH-related peptide and appeared to be an ideal model cell in which to study the effects of pGlu-Glu-ProNH2. TRH (0·01–100 nm) was found to stimulate the secretion of both GH and prolactin from GH3 cells whereas pGlu-Glu-ProNH2 had no effect within the same concentration ranges. In contrast, at micromolar concentrations pGlu-Glu-ProNH2 exhibited intrinsic TRH-like activity causing stimulation of both GH and prolactin release from GH3 cells. Both TRH and pGlu-Glu-ProNH2 appeared to act through the same intracellular signalling mechanism, causing significant increases in intracellular inositol phosphate within the expected concentration ranges. However, pGlu-Glu-ProNH2 (up to 1 mm) displaced neither [3H]TRH nor [3H]MeTRH from membrane-binding sites on GH3 cells, suggesting that the effects of the new peptide were mediated through a second receptor. The physiological relevance of these effects of pGlu-Glu-ProNH2 requires further investigation.

Journal of Endocrinology (1994) 142, 111–118
The rate of cancellous bone formation falls immediately after ovariectomy in the rat
Authors: Lean J M , Chow J W M , Chambers T J
Published: December 2008

We have recently found that administration of oestradiol-17β (OE2) to rats stimulates trabecular bone formation. It is not known, however, whether oestrogen has a similar action on bone formation rate under physiological circumstances. Oestrogen is known to suppress bone resorption, and oestrogen-deficient states in the rat, as in humans, are associated with an increase in bone resorption that entrains an increase in bone formation. To see if the latter masks a relative reduction in bone formation, due to oestrogen deficiency, we measured bone formation very early after ovariectomy, before the resorption-induced increase in bone formation becomes established. To do this, rats were administered fluorochrome labels before and after ovariectomy, spaced at weekly intervals in the first, and 3-day intervals in the second experiment.

In both experiments there was a decrease in indices of bone formation in the labelling interval immediately following ovariectomy such that, using the shorter fluorochrome intervals, the mineral apposition rate fell to 69%, the double-labelled surface to 45%, and the bone formation rate to 36% of sham-ovariectomized levels. The reduction was not sustained in the subsequent label intervals, presumably masked by the increase in bone formation attributable to increased resorption. These results suggest that if bone formation is assessed before this resorption-entrained increase in bone formation occurs, oestrogen deficiency is associated with a reduction in dynamic indices of bone formation. Thus, these experiments suggest that oestrogen stimulates bone formation under physiological circumstances, and that the osteopaenia that follows oestrogen deficiency may be attributable not only to an increase in bone resorption, but also to a relative deficiency in bone formation.

Journal of Endocrinology (1994) 142, 119–125
Human chorionic gonadotrophin: a chemoattractant for human blood monocytes, neutrophils and lymphocytes
Authors: Reinisch N , Sitte B A , Kähler C M , Wiedermann C J
Published: December 2008

Treatment of rats with human chorionic gonadotrophin (hCG) induced in the testes an inflammation-like reaction characterized by migration of leukocytes into the interstitial space. In order to find out whether hCG acts in a direct manner in this process, we tested peripheral human blood leukocyte attraction by hCG in vitro. Chemotaxis through cellulose nitrate to gradients of test substances was measured using a 48-well microchemotaxis chamber. Human CG was found to be a potent attractor of neutrophils, monocytes and lymphocytes in vitro in the picomolar concentration range. Checkerboard analyses revealed that the type of migration depends on positive concentration gradients of hCG. The chemoattractant nature of hCG is consistent with its having a role to play in regulation of tissue accumulation of these cells within the reproductive tract.

Journal of Endocrinology (1994) 142, 167–170
Manipulation of inhibin during the luteal-follicular phase transition of the primate menstrual cycle fails to affect FSH secretion
Authors: Fraser H M , Tsonis C G
Published: December 2008

The pattern of inhibin concentrations in blood during the menstrual cycle in primates has suggested an endocrine role of inhibin in the negative feedback control of FSH secretion during the luteal phase. Conversely, the fall in inhibin during the late luteal phase may play a role in the rise in serum FSH during the luteal-follicular phase transition. This hypothesis was examined by determining the effects of manipulation of inhibin on FSH secretion in stumptailed macaques. During the mid-luteal phase the putative inhibin feedback was inhibited by i.v. administration of 20 ml of ovine antiserum to human recombinant inhibin in 4 macaques. FSH secretion was unaffected during the initial 24 h period post-treatment and the timing of the rise in FSH which occurred during the subsequent luteal-follicular phase transition was normal. To determine whether the elevated serum concentrations of FSH observed during the early follicular phase could be reduced by administration of inhibin, 5 cyclic macaques were treated with 200 μg of recombinant human inhibin i.v. Serum FSH concentrations were unaltered. These results suggest that inhibin does not play a major role in modulating FSH secretion during the luteal-follicular phase transition.

Journal of Endocrinology (1994) 142, 181–186
Pharmacological characterization of the nucleotide receptors that mobilize Ca2+ ions in human parathyroid cells
Authors: Gibb C A , Cook D I , Delbridge L , Conigrave A D
Published: December 2008

We have used the fluorescent probe fura-2 to perform agonist studies of the receptor(s) that mobilizes Ca2+ ions in response to extracellular ATP in human parathyroid cells. Extracellular ATP induced Ca2+ responses in both normal and adenomatous parathyroid cells. Activation resulted in an initial small transient response during which Ca2+ ions were released from intracellular stores, followed by a prominent plateau response during which Ca2+ ions entered the cells from the extracellular fluid. The responses exhibited moderate desensitization upon repeated stimulation with ATP, and the ratio of the plateau to the peak response remained constant for any given group of activated cells. The baseline intracellular calcium concentration was 100 ± 4·3 nm (mean ± s.e.m., n=3). Following maximal activation by extracellular ATP it rose to a peak of 684 ± 45·7 nm (n=3) and a plateau level of 415 ± 9·9 nm (n=3).

We examined the effects of a variety of nucleotide species. The order of potency was: adenosine, AMP<α,β-methylene ATP<ADP<ATP≈UTP. In the concentration range 1–1000 μm, UTP (the concentration of agonist inducing a half-maximal response, EC50=2·4 μm) was slightly more potent than ATP EC50=3·6 μm), and the two nucleotides evoked similar maximal responses. In the concentration range 0·01–1·0 μm, however, there was a clear difference in the behaviour of the two nucleotides. In particular, ATP, but not UTP, evoked responses that suggested the presence of a second receptor of higher potency but markedly lower efficacy. Responses to 2-methylthioATP (2-MeSATP) in the concentration range 0·01–100 μm defined a dose–response curve that matched the lower concentration component of the ATP dose–response curve.

Together, these data suggest that two receptor species are involved in the Ca2+ responses. One is a nucleotide/P2U receptor that responds to ATP and UTP, which are approximately equipotent agonists; 2-MeSATP is only a weak agonist with respect to this receptor. The other belongs to the P2Y receptor subclass. It responds to 2-MeSATP, a selective agonist at P2Y receptors, and to ATP, but not to the pyrimidine nucleotide UTP.

Journal of Endocrinology (1994) 142, 277–283
Pancreatic hormones differentially regulate insulin-like growth factor (IGF)-I and IGF-binding protein production by primary rat hepatocytes
Authors: Denver R J , Nicoll C S
Published: December 2008

We investigated the influence of and interactions among pancreatic hormones on the secretion of insulin-like growth factor-I (IGF-I) and IGF-binding proteins (IG-FBPs) by treating primary hepatocytes from young male Long–Evans rats with insulin or glucagon in combination with rat GH (rGH). The concentration of IGF-I secreted into the medium was estimated by radioimmunoassay after formic acid-acetone cryoextraction, and secreted IGFBPs were analysed by Western ligand blot and immunoblot; accumulation of IGF-I mRNA was analysed by Northern blot. Both insulin (0·1–100 nmol/l) and rGH (0·5, 5 and 50 pmol/l) produced a dose-dependent stimulation of IGF-I secretion over a 24-h incubation period. In contrast, glucagon (0·1–100 nmol/l) inhibited IGF-I production in a dose-related manner. Glucagon (10 nmol/l) also inhibited IGF-I secretion stimulated by rGH (5 pmol/l) and insulin (10 nmol/l). Northern blot analysis of total RNA isolated from rat hepatocytes revealed that rGH (5 pmol/l) elevated IGF-I mRNA levels, glucagon (10 nmol/l) alone had no effect on this parameter, but glucagon significantly reduced IGF-I transcript accumulation in response to rGH. IGFBPs secreted by rat hepatocytes run in two molecular weight ranges on SDS-PAGE: ∼ 25 kDa (IGFBP-4) and ∼29–31 kDa (IGFBP-1 and -2); the predominant hormonally regulated IGFBP was identified as IGFBP-1. Insulin produced a dose-dependent inhibition of production of IGFBP-1, while glucagon was stimulatory; when given together at an equivalent concentration (1 nmol/l), the effects of insulin were dominant to glucagon on IGFBP-1. These observations provide support for significant opposite roles for the pancreatic hormones, insulin and glucagon, in the regulation of liver IGF-I and IGFBP-1 production. As the production of pancreatic hormones is influenced by nutritional status, these polypeptides may mediate the effects of changing nutritional state on the hormonal control of protein anabolism and glucose homeostasis by directly influencing the circulating level of liver-derived IGF-I and its binding proteins.

Journal of Endocrinology (1994) 142, 299–310
Increase of basic fibroblast growth factor (FGF) and FGF receptor messenger RNA during rat thyroid hyperplasia: temporal changes and cellular distribution
Authors: Becks G P , Logan A , Phillips I D , Wang J-F , Smith C , DeSousa D , Hill D J
Published: December 2008

Goitre was induced in adult rats by acute (1 or 2 weeks) or chronic (4 or 10 weeks) administration of methimazole together with a low iodine diet. Involution of thyroid growth was then observed at 16 weeks, 4 weeks after withdrawal of goitrogens and reversion to a normal diet. Experimental animals quickly became hypothyroid compared with controls and exhibited thyroid hyperplasia (control (n=10): total serum thyroxine (T4) 66 ±4 nmol/l, thyroid weight 5 ± 1 mg/100 g body weight, means± s.d.; experimental (n=10): T4 undetectable, thyroid weight 27 ±4 mg/100 g body weight after 2 weeks of treatment). Thyroid growth rate subsequently slowed between 2 and 10 weeks. Messenger RNA for basic fibroblast growth factor (basic FGF) and for the high-affinity FGF receptor, was compared in the thyroids and livers of control and goitrous rats by ribonuclease protection assay. Low levels of mRNA for basic FGF and its receptor were detectable in thyroids from control rats at all times, while none was detected in the livers from any animal. Basic FGF and receptor mRNAs increased, and were detected at greatest abundance in hyperplastic thyroids at 1 and 2 weeks respectively, during goitre formation, but subsequently declined in parallel with thyroid growth rate at 4 and 10 weeks. When quantified by radioimmunoassay, basic FGF extracted from thyroids was fivefold greater than in controls after 1 week of goitrogen treatment (control (n=4): 24±9 pmol/μg DNA; goitre (n=4): 100± 16 pmol/μg DNA; P<0·05). Basic FGF and FGF receptor mRNAs localized by in situ hybridization predominantly to the epithelial cell population within follicles. Localization by immunohistochemistry demonstrated that basic FGF was present in the thyroids of control rats, and was largely associated with the basement membrane of follicles. During thyroid hyperplasia, increased basic FGF immunoreactivity appeared over the cytoplasm of follicular epithelial cells and was lost from the extracellular matrix. Thyroid involution following removal of goitrogen/low iodine treatment was associated with a decrease in mRNA for basic FGF or its receptor, and a loss of immunoreactive basic FGF from the cytoplasm of follicular cells. These results suggest that autocrine expression of basic FGF and FGF receptor could contribute to thyroid hyperplasia in rats.

Journal of Endocrinology (1994) 142, 325–338
Insulin-releasing pituitary cells as a model for somatic cell gene therapy in diabetes mellitus
Authors: Stewart C , Taylor N A , Green I C , Docherty K , Bailey C J
Published: December 2008

Insulin delivery by somatic cell gene therapy was evaluated using murine pituitary AtT20MtIns-1.4 cells. These cells have been stably transfected to release human insulin by the introduction of a recombinant plasmid bearing a human preproinsulin cDNA under the control of a zinc-sensitive metallothionein promoter. 6 × 107 AtT20MtIns-1.4 cells were implanted subcutaneously into streptozotocin-diabetic mice immunosuppressed with cyclosporin A. Release of human insulin was assessed using a specific plasma human C-peptide assay. On days 1 and 2 after implantation human C-peptide concentrations were about 0·02 pmol/ml. Consumption of zinc sulphate solution (500 mg/l) as drinking fluid for days 3–5 increased plasma human C-peptide concentrations to 0·11 ±0·01 pmol/ml (mean±s.e.m.), n=11, P<0·01, and concentrations declined when zinc was discontinued. The extent of hyperglycaemia was slightly lower (P<0·05) than in a group implanted with non-transfected AtT20 cells. The study was terminated after 9 days, and tumour-like aggregations of implanted cells were identified at autopsy. These comprised a large necrotic core with insulin-containing cells at the periphery. The study provides support for the view that somatic cell gene therapy offers a potential approach to insulin delivery in diabetes mellitus.

Journal of Endocrinology (1994) 142, 339–343
Is ovarian relaxin a stimulus to placental protein 14 secretion in pregnancy?
Authors: Critchley H O D , Healy D L , Chard T
Published: December 2008

The objective of this study was to investigate whether relaxin might be involved in placental protein 14 (PP14) secretion by measuring serum levels of PP14 during labour and post partum in normal women with a term pregnancy given vaginal human recombinant relaxin (rhRlx) gel for induction of labour. A randomized double-blind controlled trial was conducted on 11 women with a singleton pregnancy at term admitted for induction of labour. Comparison of serum PP14 and relaxin concentrations in the control and treated groups of subjects revealed that there was an increase in serum relaxin concentrations in women receiving 3 mg or 6 mg relaxin. There was no difference in serum PP14 levels between the control and treatment groups. These findings do not support the hypothesis that relaxin is involved in the control of PP14 secretion. However, the failure of any response might be a consequence of the very small increase in systemic levels of relaxin produced by topical vaginal administration of rhRlx. Furthermore, these measurements were made in late pregnancy and hence may not relate to the events in early pregnancy, when serum levels of PP14 are maximal.

Journal of Endocrinology (1994) 142, 375–378
Prepartum adrenocortical maturation in the fetal foal: responses to ACTH1–24
Authors: Silver M , Fowden A L
Published: December 2008

The present study was carried out on 19 chronically catheterized mares and fetuses in late gestation (term >320 days). In six animals which were monitored up to the time of delivery of a live foal, plasma and amniotic fluid cortisol concentrations remained low until 4–5 days before parturition when there was a rapid, significant rise (P<0·05) which was not accompanied by any corresponding changes in maternal plasma cortisol. Circulating fetal ACTH concentrations became more variable close to delivery and ANOVA revealed no significant increases during this critical period, although a negative correlation between plasma ACTH and time to delivery was observed (P<0·05).

Tests on fetal adrenal responsiveness to exogenous ACTH1–24 were carried out on ten animals. Before 295 days of gestation no significant increases in fetal plasma cortisol above its basal level of 20–30 nmol/l could be elicited by ACTH, administered as a single i.v. injection (1–2 μg/kg). By 304 ± 3 days (mean ± s.e.m.) small but significant (P<0·05) increments in plasma cortisol were detected after ACTH, while in the oldest group (313 ±2 days) significant (P<0·01) 50–60% increments were seen throughout the test period (2 h). Only one fetus was tested within 3 days of delivery and here a fourfold rise in plasma cortisol was evoked by ACTH.

When changes in endogenous levels of circulating ACTH and cortisol were monitored every 15 min over 1·5- to 2-h periods in late gestation, rises in ACTH were only accompanied by concomitant increases in plasma cortisol in fetuses within 5 days of delivery (correlation coefficient r=0·58, P<0·01). Before this time, plasma cortisol concentrations remained at basal levels irrespective of any fluctuations in plasma ACTH. These findings indicate that the adrenal cortex of the fetal foal is relatively quiescent and insensitive to ACTH for most of the latter part of gestation, but that a short rapid escalation in circulating cortisol precedes its delivery.

Journal of Endocrinology (1994) 142, 417–425
Dysfunctional growth hormone receptor in a strain of sex-linked dwarf chicken: evidence for a mutation in the intracellular domain
Authors: Agarwal S K , Cogburn L A , Burnside J
Published: December 2008

The sex-linked dwarf (dwdw) chicken represents a valuable animal model for studying GH insensitivity and the consequence of mutations in the GH receptor (GHR) gene. We have recently reported undetectable hepatic GH-binding activity and an aberrantly sized transcript in a strain of dwdw chickens obtained from Arbor Acre Farms, Inc. (Glastonbury, CT, USA). Southern blot analysis of the chicken GHR (cGHR) gene revealed a restriction-fragment length polymorphism in HindIII and EcoRI digests of genomic DNA in this strain of dwdw chicken. In order to localize the molecular mutation, we analysed the gene structure and determined the complete sequence of the 3' untranslated region (3' UTR) of the normal cGHR. With the use of this information, we located a large deletion in the 3' end of the cGHR gene of the Connecticut (CT) strain of dwdw chicken. This deletion (1773 bp) contained 27 highly conserved amino acids of the 3' end of the coding region, the in-frame stop codon, a less frequently used poly(A) signal that is normally found 445 bp downstream of the stop codon, and a large portion of the 3' UTR. Because of this deletion, 27 novel amino acids were substituted and the open reading frame was extended for an additional 26 amino acids before reaching the transcriptional termination site. The predicted amino acid sequence of the novel carboxyl-terminus of the dwdw cGHR is largely hydrophobic with a polylysine tail, whereas the carboxyl-terminus of the wild-type (DwDw) cGHR is composed of hydrophilic amino acids. Western blot analysis using antisera directed against the extracellular domain of the cGHR confirmed that the mutant transcript was translated. These observations suggested that the mutation in the intracellular domain results in expression of a dysfunctional cGHR which could account for the phenotype of the CT dwdw chicken.

Journal of Endocrinology (1994) 142, 427–434
Interaction of endothelin-1 with porcine thyroid cells in culture: a possible autocrine factor regulating iodine metabolism
Authors: Tsushima T , Arai M , Isozaki O , Nozoe Y , Shizume K , Murakami H , Emoto N , Miyakawa M , Demura H
Published: December 2008

Although endothelins were originally discovered as peptides with vasoconstrictor activity, recent studies have indicated a number of endothelin (ET)-induced hormonal functions in various tissues. We have studied the interaction of endothelins with porcine thyroid cells in culture. Specific binding of 125I-labelled ET-1 was demonstrated in porcine thyroid cells. The binding was displaced equally by unlabelled ET-1 and ET-2, but receptor affinity for ET-3 was lower than that for ET-1 and -2. Scatchard analysis of the data revealed a single class of high-affinity ET-1 receptors with a Kd of 0·45 nmol/l and a binding capacity of 2100 sites/cell. SDS-PAGE and autoradiography of 125I-labelled ET-1 cross-linked with thyroid cell membranes demonstrated ET-1 binding sites with an apparent molecular weight of 50 kDa. These results indicated that ET-1 receptors in thyroid cells are type A ET receptors. In association with the presence of ET-1 receptors, porcine thyroid cells responded to ET-1 and ET-2 with an increase in c-fos mRNA expression. Although ET-1 did not affect DNA synthesis stimulated by either EGF or IGF-I, it dose-dependently inhibited TSH-induced iodide uptake and also inhibited iodide uptake stimulated by forskolin and 8-bromo-cAMP. ET-1 had no effect on TSH-stimulated cAMP production. Thus, ET-1 inhibited TSH-induced iodine metabolism by acting at the steps distal to cAMP production. In agreement with a recent report, immunoreactive ET-1 was detected in medium conditioned by porcine thyroid cells. Antibody to ET-1 was found to increase TSH-induced iodide uptake. These results are compatible with the notion that ET-1 negatively regulates TSH-induced iodide uptake in an autocrine manner.

Journal of Endocrinology (1994) 142, 463–470
Effect of blocking oestrogen synthesis with a new generation aromatase inhibitor CGS 16949A on follicular maturation induced by pregnant mare serum gonadotrophin in the immature rat
Authors: Selvaraj N , Shetty G , Vijayalakshmi K , Bhatnagar A S , Moudgal N R
Published: December 2008

While the endocrine role of oestrogen is well established, its function in follicular maturation as an autocrine or paracrine regulator is less well understood. This study was designed to delineate the requirement of oestrogen for follicular development in immature rats. Exogenous gonadotrophin (25 IU pregnant mare serum gonadotrophin (PMSG) per rat) was administered to 21- to 23-day old female rats to induce follicular growth and development. In the experimental animals, synthesis of oestrogen was blocked by implanting an Alzet pump containing the aromatase inhibitor (AI) CGS 16949A (fadrozole hydrochloride; 50 μg/rat per day). The treatment resulted in blockade of the PMSG induced increase in both serum and intrafollicular oestrogen (>95%), thus leading to an inhibition in uterine weight increment. Compared with the controls, ovarian weight increased markedly in both the PMSG (295%)- and PMSG+AI (216%)-primed animals.

There was no significant difference in either the proliferative capabilities of the ovarian granulosa cells or their responsiveness to human chorionic gonadotrophin (hCG; 200 pg/ml) and ovine FSH (20 ng/ml) between the PMSG- and PMSG+AI-treated groups. Histological examination of the ovary, however, indicated a decrease in the number of healthy antral follicles in the AI-treated group compared with the PMSG-primed animals but both the groups showed a percentage increase over the controls (PMSG, 225; PMSG+AI, 158). The responsiveness of the animals to an ovulatory dose of hCG was drastically reduced (>80% inhibition of ovulation) in the oestrogen-deprived animals; this could be overriden by exogenous administration of oestrogen. In conclusion, although blocking oestrogen synthesis in the PMSG-primed rat does not seem to alter the functional properties of the isolated granulosa cells in vitro there appears to be an effect on the number of follicles which complete maturation and are able to ovulate in vivo.

Journal of Endocrinology (1994) 142, 563–570
Circulating gonadotrophin surge-attenuating factor from superovulated women suppresses in vitro gonadotrophin-releasing hormone self-priming
Authors: Fowler P A , Cunningham P , Fraser M , MacGregor F , Byrne B , Pappas A , Messinis I E , Templeton A
Published: December 2008

A penfusion system based on ovine pituitary tissue explants was used to investigate the effects of follicular fluid (hFF) and serum from superovulated women on pituitary responsiveness to gonadotrophin-releasing hormone (GnRH). The specific aims of the study were to determine both if gonadotrophin surge-attenuating factor (GnSAF) bioactivity is present in the peripheral circulation as well as in the follicles of superovulated women and if GnSAF suppresses GnRH self-priming in vitro. Two pulses of GnRH, 1 h apart, produced marked peaks in LH secreted from control chambers, with GnRH self-priming evident in the significant difference between the first (134·4±1·7–232·1±24·0% of basal secretion) and second (183·9±15·8–313·9±14·0% of basal secretion) LH peaks. Both follicular fluid and serum pooled from two different groups of women produced marked suppression of the first (unprimed) and second (primed) LH peaks. The hFF reduced the first LH peak to 69·6±7·8 and 60·2±9·7% and the second LH peak to 57·4±6·7 and 42·6±6·5% of control LH secretion. Overall, the serum reduced the first and second LH peaks to 76·8±4·2 and 62·9±3·6% of control respectively. These results demonstrated that GnSAF bioactivity suppresses GnRH self-priming, and is present in both the peripheral circulation and hFF. The same material administered to dispersed ovine pituitary monolayers produced similar marked suppression of GnRH-induced LH secretion, with approximately 50-fold less GnSAF bioactivity in serum compared with hFF. Combined doses of oestradiol and progesterone, or hFF from large follicles containing little GnSAF, produced stimulation of GnRH-induced LH secretion and GnRH self-priming (second peaks 78·1±38·9 and 27·4±15·7% respectively higher than first peaks). Thus, in conclusion, GnSAF in hFF and serum markedly attenuated both unprimed and primed pituitary response to GnRH, virtually abolishing the GnRH self-priming effect.

Journal of Endocrinology (1994) 143, 45–54
The effects of corticotrophin-releasing hormone, arginine vasopressin and their antagonists on ACTH release from perifused horse anterior pituitary cells
Authors: Ellis M J , Mulligan R S , Evans M J , Donald R A
Published: December 2008

Antagonists are useful for probing hormone action and receptor characteristics. In this study we have investigated the inhibitory effects of analogues of arginine vasopressin (AVP) and corticotrophin-releasing hormone (CRH) on stimulated release of immunoreactive ACTH from perifused equine anterior pituitary cells in vitro. Our aims were to gain some insight into the characteristics of the CRH and AVP receptors of the horse pituitary and to establish whether the response induced by AVP and CRH together could be blocked by combining antagonists. Experimental design included 5-min pulses of AVP (12·5 nmol/l), CRH (0·3 nmol/l) or CRH plus AVP given every 40 min alternately with pulses of secretagogue(s) plus appropriate antagonist(s). The effect of combined antagonists on the response to lower secretagogue concentrations (CRH, 0·03 nmol/l plus AVP, 2·5 nmol/l) was also tested. Response in the presence of an antagonist was compared with the mean response to secretagogue in the immediately preceding and following pulse and was expressed as per cent expected ACTH.

The ACTH response to AVP was inhibited over the dose range 0·4–50 μmol/l by Phaa-d-Tyr(Et)2Lys6Arg3VP (P<0·002; ANOVA) and by d(CH2)5[Tyr(Me)2]AVP (P<0·001). Suppression of the expected ACTH response to AVP by these two antagonists was most effectively achieved by antagonist concentrations of 10 μmol/l (to 28±2·1%) and 25 μmol/l (to 22±5·1%) respectively. Inhibition was not improved by preinfusion compared with a bolus pulse. Aaa-d-Tyr(Et)2Val4Abu6Arg8·9VP and the non-peptide antagonist OPC-21268 had no inhibitory effect. Two α-helical (α-h) analogues of CRH, (α-hCRH(12–41) and α-hCRH(9–41) tested over the dose range 0·5–5 μmol/l, suppressed CRH-induced ACTH secretion (P<0·001) but CRH(23–41) had no significant effect. The α-hCRH(12–41) achieved greater suppression of ACTH release than the (9–41) derivative (8·7±4·2% compared with 19·3±3·5% of the expected ACTH response). Combination of d(CH2)5[Tyr(Me)2]AVP (25 μmol/l) plus α-hCRH (12–41) (5·0 μmol/l) achieved suppression to −0·5±1·3% and 0·8±1·5% of the expected response to CRH+AVP at 0·3+12·5 nmol/l and 0·03+2·5 nmol/l respectively. These effects were greater than seen by the individual antagonists alone.

The antagonist effects suggest that the CRH and AVP receptors of the equine pituitary have similar properties to those from other species and are consistent with the pituitary AVP receptor being unlike the V2 receptor and resembling but not being identical to the V1 type. We also conclude that α-hCRH(12–41) and d(CH2)5[Tyr(Me)2]AVP can together block the ACTH response to CRH plus AVP and suggest that these antagonists should provide a means of investigating additional secretagogues involved in ACTH release in the horse.

Journal of Endocrinology (1994) 143, 85–93