bluuebunny/crossref_metadata_2025 huggingface dataset:
Ontogeny and nutritional regulation of the serum growth hormone-binding protein in the rat
Authors: Mulumba Nkuadi , Massa Guy , Ketelslegers Jean-Marie , Maes Marc
Published: June 2009

The ontogeny and the nutritional regulation of the serum growth hormone-binding protein in Wistar rats was studied in vitro using Ultrogel AcA34 filtration of serum incubated with 125I-bovine growth hormone. The level of the specific binding of GH to serum GH-binding protein was low in 1-week-old rats (female rats 2.3±0.9%; N=6, and male rats 2.1±8%; N=6 ) and increased with puberty, to reach 10-fold higher levels in 12-week-old adult female (26.1±2.3%; N=6) and 5-fold higher levels in adult male rats (11.2±0.9%; N=6). From 6 weeks of age and onwards, the level of serum GH-binding protein was significantly higher in female than in male rats, reflecting sexual dimorphism. The nutritional dependence of GH-binding protein was supported by the 46% decline of serum GH-binding protein levels in 6-week-old female rats fasted for 3 days (11.6±0.9 and 6.3±1.1% in control and fasted rats, respectively; N=8/group; p<0.001). After 4 days of refeeding, no difference was found between control and experimental animals. During development and after nutritional manipulation, Scatchard analysis revealed that the changes in GH-binding protein were due to changes in binding capacity and not affinity. The levels of serum GH-binding protein were positively correlated with the levels of hepatic GH binding sites, suggesting that the regulation of both proteins is closely related during development and in states of nutritional sufficiency and deprivation.
Hormonal effects of apomorphine and cholecystokinin in pigs: modification of the response to cholecystokinin by a dopamine antagonist (metoclopramide) and a kappa opioid agonist (PD117302)
Authors: Parrott R. F. , Ebenezer I. S. , Baldwin B. A. , Forsling M. L.
Published: June 2009

Three experiments were carried out to investgate some of the mechanisms involved in the endocrine responses of pigs to the emetic agents apomorphine and cholecystokinin. In Experiment 1, plasma levels of vasopressin and cortisol were measured in prepubertal pigs (N=5) treated with iv apomorphine (25 μg/kg) or saline vehicle. In Experiment 2, concentrations of vasopressin and cortisol were determined in pigs given iv sulphated cholecystokinin octapeptide (1.3 μg/kg), metoclopramide (300 μg/kg), metoclopramide + cholecystokinin, and an oral dose of the kappa opioid agonist PD 117302 (20 μg) alone, or followed by iv cholecystokinin. In Experiment 3, operant feeding behaviour was quantified in pigs (N=4) given cholecystokinin (1 μg/kg) or cholecystokinin preceded by oral PD 117302. Following apomorphine injection in Experiment 1, there was a rapid, transient, rise in plasma vasopressin. Cholecystokinin had a similar effect on vasopressin secretion in Experiment 2 and also induced a later rise in plasma cortisol. Pre-treatment with metoclopramide appeared to reduce both of these effects of cholecystokinin, but only the decrease in cortisol was statistically significant. However, oral administration of PD 117302 abolished the effect of cholecystokinin on vasopressin release and reduced the subsequent rise in cortisol. The inhibitory effect of cholecystokinin on feeding was unaltered by PD 117302 treatment in Experiment 3. The results obtained with apomorphine and metoclopramide, together, suggest that the neuroendocrine effects of cholecystokinin in the pig may involve an action on central dopamine receptors while the effects of PD 117302 indicate that kappa opioids may modify the hormonal responses to cholecystokinin by a peripheral action.
Cortisol increases the susceptibility of rat islets to interleukin 1
Authors: Stahl Matthias , Cheng Hua , Linde Susanne , Nielsen Jens Høiriis
Published: June 2009

Interleukin 1β has been proposed to play an essential role in the pathogenesis of IDDM by direct interaction with the pancreatic beta-cell. Glucocorticoids are widely used as immunosuppressive agents and have been suggested to interfere both with the production and action of interleukin 1. The aim of the present study was to evaluate the interaction between cortisol and interleukin-1 on the pancreatic beta-cell function in vitro. Newborn rat islets were precultured for seven days before they were exposed to interleukin 1 with or without addition of cortisol. The release of insulin to the culture medium was followed and the insulin content and biosynthesis were measured after one week in culture. Cortisol, 10−6 mol/l, resulted in a 50% lower rate of release during the culture period and a similar reduction in storage and biosynthesis of insulin in the islets at the end of the culture period. In the control islets interleukin 1, 0.5 μg/l, resulted in an early increase in insulin release followed by a marked reduction. In the cortisol-treated islets interleukin 1 increased the release up to 72 h followed by a moderate decrease. In the control islets, interleukin 1 reduced the insulin content to about 50%, whereas in the cortisol-treated islets interleukin 1 resulted in an even greater reduction, to about 30%. This additional effect of cortisol seems not to be due to an augmented cytotoxic effect of interleukin 1 as indicated by the DNA content of the islets and the viability of the cells. In conclusion, cortisol treatment augmented both the early stimulatory and the late inhibitory effects of interleukin 1 on insulin release and biosynthesis in isolated pancreatic islets in culture.
Long-term growth hormone treatment in growth hormone deficient adults
Authors: Jørgensen Jens O. L. , Pedersen Søren A. , Thuesen Leif , Jørgensen Jørgen , Møller Jens , Müller Jørn , Skakkebæk Niels E. , Christiansen Jens S.
Published: June 2009

Growth hormone treatment in GH-deficient adults has proved beneficial in recent short-term trials, but long-term results have not yet been reported. Thirteen GH-deficient adults (4 females, 9 males; mean (sem) age 26.4 (1.7) years), who had completed 4 months of GH therapy in a double-blind placebo-controlled cross-over study were followed, for further 16.1 (0.8) months of uninterrupted GH therapy in an open design. A significant mean increase of 1.3 cm in linear height was recorded, whereas body mass index remained unchanged. Mean muscle volume of the thigh, estimated by computerised tomography, increased significantly compared with that of the initial placebo period (p=0.01), and a slight decrease was recorded in adipose tissue volume of the thigh (p=0.10) and subscapular skinfold thickness (p=0.10). Still, the muscle to fat ratio of the thigh was significantly lower compared with that of normal subjects (72.6/27.4 vs 77.9/22.1) (p<0.01). The mean isometric strength of the quadriceps muscles increased significantly during long-term GH therapy (p<0.01), but remained lower compared with that of normal subjects (1.66 (0.10) vs 2.13 (0.11) Nm/kg body weight). Exercise capacity performed on a bicycle ergometer increased significantly after long-term therapy (p<0.05), but still did not reach the values seen in normal subjects (22.5 (3.4) vs 37.4 (4.2) watt · min · kg−1· No adverse reactions were recorded during long-term therapy and hemoglobin A1c remained unchanged. These data suggest that long-term GH replacement therapy in GH-deficient adults has beneficial effects on several physiological features which are subnormal in these patients.
Thyroid dysfunction in 85-year-old men and women. Influence of non-thyroidal illness and drug treatment
Authors: Sundbeck Görel , Edén Staffan , Jagenburg Rudolf , Lindstedt Göran
Published: June 2009

Serum TSH and free T4 were determined by chemiluminometric assays in 601 women and 285 men aged 85 years from the population study "70-year-old people in Gothenburg, Sweden". For individuals with serum TSH concentration above 6.0 mU/l, "antimicrosomal" antibodies were determined, to assess the etiology of the elevated TSH concentration. Clinical follow-up was done of survivors until the age of 88, and records were inspected also for individuals who died before that age. On the basis of these evaluations the prevalence of previously undetected hypothyroidism was estimated to 4.0% in women and 2.5% in men. Previously undetected hyperthyroidism was found in 2, at the most 4, out of 601 women; in one out of 285 men the diagnosis could not be excluded. Possible confounding factors for the evaluation of TSH and/or free T4 concentrations were analysed by permutation t-test followed by multiple regression analysis, which revealed correlations of log TSH concentration to body mass index (p<0.05), serum creatinine concentration (p<0.05), and diabetes mellitus (inverse relationship, p<0.01). Correlation was found of free T4 concentration to treatment with non-selective β-blocking agents (p<0.001) and digitalis glycosides (p<0.01). However, none of the factors influencing TSH and/or free T4 concentrations had any major influence on reference limits, nor could they account for individuals with "outlier" values.
Failure to confirm a growth hormone-releasing activity of corticotropin-releasing hormone in acromegaly: Comparison with the effects of other hypothalamic hormones
Authors: Watanobe Hajime , Sasaki Shinsuke , Takebe Kazuo
Published: June 2009

We re-examined whether CRH stimulates GH secretion in acromegaly. Human CRH (100 μg) was given as an iv bolus to 15 patients with active acromegaly, and plasma GH levels were measured before and at intervals up to 120 min after the injection. For comparison, we assessed in all the patients the effects of TRH (500 μg), GnRH (100 μg), vasoactive intestinal peptide (100 μg) and peptide histidine methionine (100 μg), which are known paradoxically to stimulate GH secretion in acromegaly. A paradoxical GH response (>50% above the basal) to TRH, GnRH, vasoactive intestinal peptide and peptide histidine methionine was observed in 12 (80%), 4 (27%), 5 (33%) and 2 (13%) patients, respectively. All the patients were responsive to at least one of these 4 peptides. However, none of the patients showed a positive GH response to hCRH. These results do not support a GH-releasing activity of CRH in acromegaly. Even if CRH has such an effect, it does not appear as potent as TRH, GnRH, vasoactive intestinal peptide and peptide histidine methionine. However, the possibility cannot be excluded that our negative data might have been due to the use of hCRH vs ovine CRH in earlier studies.
Thyrotropin receptor antibodies following treatment with recombinant α-interferon in patients with hepatitis
Authors: Fonseca V. , Thomas M. , Dusheiko G.
Published: June 2009

We measured thyrotropin receptor antibodies in serum obtained from 2 groups of patients participating in clinical trials of recombinant interferon-α 2b for viral hepatitis. Group I: Patients with hepatitis B (N=8), received interferon 5×106 units thrice weekly for 4 months. Group II: Patients with non-A, non-B hepatitis (N=16) were randomized to receive interferon in a dose of either 0.25×106 or 3×106 U thrice weekly for 6 months and then crossed over to receive the other dosage schedule for a further 6 months. None of the patients developed thyrotoxicosis. Thyrotropin receptor antibody activity was detectable within the "normal range" (<10 U/l) in 6 patients prior to treatment. In Group I, thyrotropin receptor antibodies became detectable in 6 patients on treatment, in 4 of whom it was 10 U/l. In Group II, thyrotropin receptor antibody activity was unchanged on low-dose interferon, but on the higher dose became detectable in 9 patients, in 7 of whom it was >10 U/l. We conclude that treatment with interferon is associated with the development of thyrotropin receptor antibodies in a large proportion of patients. It is possible that in some patients treated with higher doses of interferon the increase in thyrotropin receptor antibody activity may be sufficient to induce hyperthyroidism.
Chronic treatment with Parlodel LAR® of patients with prolactin-secreting tumours. Different responsiveness of micro- and macroprolactinomas
Authors: Maraschini Caterina , Moro Mirella , Masala Antonio , Toja Paola , Alagna Sergio , Brunani Amelia , Rovasio Pier Paolo , Ginanni Anna , Lancranjan Ioana , Cavagnini Francesco
Published: June 2009

Forty-one patients with prolactinoma (25 micro-, 16 macroprolactinomas) were treated with a long-acting injectable preparation of bromocriptine (Parlodel LAR®, Sandoz), 25-100 mg (mostly 50 mg) im every 4-8 weeks for as long as 43 months (median 19 months). The first injection caused a prompt fall of plasma PRL which reached its nadir value after 3 days. Thereafter, hormone levels remained well below initial values for 4 weeks or longer, though with the tendency, more pronounced in microprolactinoma patients, to rise again toward baseline. The prevalence of PRL normalization was greater in the macro- than in the microprolactinoma group. By repeated injections plasma PRL could be kept close to or within the normal limits in most of the patients. However, the extent of PRL inhibition was significantly greater in macro- than in microprolactinoma patients (p<0.01). Clinical improvement occurred in the majority of the patients, shrinkage of the tumour in 50% of them. Adverse reactions were generally mild or of moderate severity and subsided spontaneously in 24 h. They were less frequent (NS) and less severe (p<0.05) in macro- than in microprolactinoma patients. In conclusion: a. injectable bromocriptine (Parlodel LAR) is a highly effective preparation particularly suitable for the long-term treatment of tumourous hyperprolactinemia; b. patients with macroprolactinoma exhibit, compared with microprolactinoma patients, better responsiveness and better tolerability to injectable bromocriptine.
Circulating activated T cell subsets in autoimmune thyroid diseases: Differences between untreated and treated patients
Authors: Ohashi Hiroyuki , Okugawa Tadamasa , Itoh Mitsuyasu
Published: June 2009

To investigate the relationships between lymphocyte subsets and thyroid function, peripheral blood lymphocytes were analysed with cell surface antigens of activated (HLA-DR+) T, helper T (CD4+2H4−, CD4+4B4+) and suppressor-inducer T (CD4+2H4+, CD4+4B4−) cells subsets in 56 patients with Graves' disease, 16 patients with Hashimoto's thyroiditis, 7 patients with typical subacute thyroiditis and 2 patients with the thyrotoxic phase of autoimmune thyroiditis. Both patients with Graves' disease and Hashimoto's thyroiditis had increased percentages of HLA-DR+T (Ia+CD3+) cells as well as HLA-DR+ helper-inducer T (Ia+CD4+) cells, which seemed to be independent of treatments. The percentage of HLA-DR+ suppressor-cytotoxic T (Ia+CD8+) cells was increased in euthyroid or hypothyroid patients with Graves' disease following treatment, but was normal in hyperthyroid patients. The percentages of Ia+CD4+ cells and Ia+CD8+ were also increased in patients with thyrotoxic phases of subacute thyroiditis and autoimmune thyroiditis, whereas these abnormal values normalized in the remission phase. These findings suggest that an increase in Ia+CD4+ cells characteristically occurs during immune system activation in patients with hyperthyroid Graves' disease, Hashimoto's thyroiditis and the thyrotoxic phase of subacute thyroiditis, whereas the activated CD8+ cells in Graves' disease are induced by antithyroidal therapy.
Effects of exogenous growth hormone pretreatment on the pituitary growth hormone response to growth hormone-releasing hormone alone or in combination with pyridostigmine in Type I diabetic patients
Authors: Giustina Andrea , Bossoni Simonetta , Bodini Corrado , Cimino Antonino , Pizzocolo Giuseppe , Schettino Maurizio , Wehrenberg William B.
Published: June 2009

We evaluated the effects of iv pretreatment with exogenous GH on the GH response to GHRH either alone or in combination with pyridostigmine in 14 Type I diabetic patients and 6 normal subjects. All the subjects received an iv bolus injection of biosynthetic human GH, 2 IU; 2 h later they received either a. pyridostigmine, 120 mg orally, or b. placebo, 2 tablets orally, followed 1 h later by iv injection of GHRH(1-29) NH2, 100 μg. In normal subjects the median GH peak after GH+GHRH was 1.8, range 1.2-6.9 μg/l. Pyridostigmine enhanced the GH response to GHRH in all subjects. The median GH peak after pyridostigmine+ GH+GHRH was 32.7, range 19.8-42.1 μg/l (p<0.001 vs GHRH alone). Seven diabetic subjects had median GH peaks after GH+GHRH >6.9 μg/l (the maximum GH peak after GH+GHRH in normal subjects) (group A: median GH peak 35.7, range 21.7-55 μg/l). The other diabetic subjects had GH peak lower than 6.9 μg/l (group B: median GH peak 4.4, range 2.1-6.5 μg/l). Pyridostigmine significantly increased the GH response to GHRH in group B patients (median GH peak 29.3, range 15.7-93.4 μg/l, p<0.001 vs GH+GHRH alone), but not in group A patients (median GH peak 39.9, range 21.9-64.9 μg/l). Group A diabetic patients were younger and had higher HbA1c and blood glucose levels than group B patients. In those diabetic patients with an exaggerated GH response to GH+GHRH, pyridostigmine failed to cause the increase in GH secretion observed in diabetic and control subjects with no responses to GH+GHRH. It can be suggested that elevated 24-h GH levels in some Type I diabetic patients may be due to decreased somatostatinergic tone which in turn causes altered autoregulation of GH secretion. We hypothesize that this finding is a consequence of a reset of the hypothalamic control of GH secretion caused by a chronically elevated blood glucose level in this subpopulation.
On the role of the peptide galanin in regulation of growth hormone secretion
Authors: Hulting Anna-Lena , Meister Björn , Carlsson Lena , Hilding Agneta , Isaksson Olle
Published: June 2009

The effects of the peptide galanin on growth hormone secretion were studied in vitro using cultured rat and human anterior pituitary cells, and in vivo by iv administration of galanin in both rats and humans. Galanin in concentrations from 10 nmol/l to 1 μmol/l did not alter basal GH release, but slightly inhibited GHRH-stimulated GH release from cultured rat anterior pituitary cells. Galanin (1 μmol/l) did not significantly change basal or GHRH-stimulated GH secretion from cultured human anterior pituitary cells. In contrast, iv injection of 1 μg (300 pmol) galanin to rats induced an increase in plasma GH that was reproducible at repetitive injections. The galanin-induced GH release in rats was of a lower magnitude than the increase in plasma GH after iv injections of GHRH, and was seen with a 5-15 min delay in comparison to iv administered GHRH. In man, iv infusions of galanin (40 pmol ·kg−1 · min−1 · (40 min)) also caused a significant increase in plasma GH, but it occurred 25-30 min after the beginning of the infusion. These results suggest an indirect action of galanin on GH release in both rats and humans, i.e. galanin does not directly affect the somatotropes. In agreement with a central action, no binding sites for galanin could be demonstrated in the rat anterior pituitary by autoradiography. Since galanin did not affect somatostatin release from fragments of rat mediobasal hypothalamus, the stimulatory effects of galanin on GH release are most likely mediated via a stimulatory effect on GHRH neurons.
Biosynthesis of 16-androstene steroids and testosterone by porcine testis tissue in vitro: effect of age and relationships with fat 5α-androstenone levels in vivo
Authors: Louveau Isabelle , Bonneau Michel , Gower D. B.
Published: June 2009

The relationships between testicular 16-androstene and testosterone formation in young pigs and levels of 5α-androstenone in fat exhibited at older ages were investigated. Testis tissue samples were taken from Large White male pigs at 75, 100 and 125 days of age (8 pigs per age group) and incubated with a mixture of [3H]progesterone and [14C]pregnenolone. 5α-androstenone levels in fat were measured in all 24 pigs at 125, 145 and 170 days of age. Less androstadienone, more 3α-androstenol and 11-fold more 3β-androstenol + androstadienol were synthesized from pregnenolone than from progesterone. 5α-androstenone synthesis increased significantly between 100 and 125 days, whereas that of androstadienone declined between 75 and 100 days of age. Litter had a significant effect on all 16-androstene rates of formation. Fat 5α-androstenone levels were positively correlated with 5α-androstenone formation from both precursors. They were correlated with 3β-androstenol + androstadienol (positively) and testosterone (negatively) rates of synthesis from progesterone. It is concluded that in vitro measurements of 5α-androstenone formation by testis tissue could be used as an early predictor of fat 5α-androstenone levels exhibited at older ages.
Balb/C mice immunized with either xenogeneic or syngeneic TSH produce immunoglobulins with anti-TSH and thyroid-stimulating activities
Authors: Ben-David Chava , Gafny Mira , Sirkis Nava , Gordon Amirav , Gross Jack
Published: June 2009

Balb/C mice were immunized with bTSH (xenogeneic TSH) or extracts of Balb/C pituitaries (containing syngeneic TSH), either intracutaneously with Freund's adjuvant or intrasplenically. After bTSH, all blood samples contained anti-TSH antibodies. Thyroid-stimulating activity was assayed on FRTL-5 cells. Of 80 sera from immunized mice, 33 induced an increase in 99mTcO4 uptake, and 31/79 induced an increase in thyroidal 3[H]thymidine uptake by thyrocytes. With syngeneic TSH, anti-TSH antibodies were found in 10/19 mice. Immunoglobulins increasing thyrocyte technetium uptake were found in 14/19 mice, and immunoglobulins that stimulated thymidine uptake in thyrocyte DNA were detected in 12/19 sera. After immunization with both types of TSH, sera of some mice showed only one of the two bioactivities. Hybridomas were prepared with splenic lymphocytes of the mice immunized with either of the TSH preparations. These secreted TSH-binding immunoglobulins or immunoglobulins which stimulated thymidine or technetium uptake by the thyrocytes. One of the hybridomas from mice immunized with pituitary extract secreted a monoclonal antibody which stimulated thyroidal thymidine uptake, but inhibited bTSH-induced 99mTcO4 uptake. These findings might suggest that the anti-idiotypic network acting on TSH as an antigen could be involved in the pathogenesis of stimulatory antibodies in thyroid disease.
Insulin-like growth factor II and transforming growth factor β1 regulate insulin-like growth factor I secretion in mouse bone cells
Authors: Tremollieres Florence A. , Strong Donna D. , Baylink David J. , Mohan Subburaman
Published: June 2009

Bone cells in culture produce and respond to growth factors, suggesting that local as well as systemic factors regulate bone volume. Previous studies have shown that IGF-I is the major mitogen produced by mouse bone cells and that its production is regulated by systemic agents such as PTH and estrogen. Because IGF-II and transforming growth factor β1 have been shown, respectively, to increase and decrease MC3T3-E1 cell proliferation, we tested the hypothesis that these two growth factors modulate the production of IGF-I in this cell line. In order to eliminate artifacts owing to IGF binding proteins, conditioned media samples were pretreated with IGF-II before measurement of IGF-I by RIA. After 24 h treatment at a density of 2.5× 104 cells/cm2, IGF-II (10 μg/l) induced a 2.2-fold increase compared with untreated control (9.5±1.5 vs 4.2±0.44 pg/μg protein, p<0.001), whereas transforming growth factor β1 (1 μg/l) caused a 66% decrease in IGF-I production (1.5±0.3 vs 4.2±0.44 pg/μg protein, p<0.001). Both IGF-II and transforming growth factor β1 regulated IGF-I production in a dose-, time- and cell density-dependent manner. The lowest effective doses for IGF-II and transforming growth factor β1 were 1 and 0.01 μg/l, respectively. These results support a role for IGF-II and transforming growth factor β1 as potent modulators of IGF-I secretion in mouse bone cells. Furthermore, regulation of IGF-I production in bone cells by IGF-II and transforming growth factor β1 in an autocrine/paracrine manner could represent a component part of the mechanism whereby the skeleton locally adapts in reponse to external stimuli.
Comparative effects of chronic administration of the non-steroidal antiandrogens flutamide and Casodex on the reproductive system of the adult male rat
Authors: Chandolia Ramesh K. , Weinbauer Gerhard F. , Simoni Manuela , Behre Hermann M. , Nieschlag Eberhard
Published: June 2009

The effects of chronic blockade of androgen action by the antiandrogens flutamide and Casodex on serum and pituitary concentrations of LH and FSH, serum and testicular androgen levels, reproductive organ weights, and on spermatogenesis were compared in the adult rat. Animals were treated for 3 and 8 weeks with vehicle, Casodex (20 mg · kg−1 · (day)−1, flutamide (20 mg · kg−1 · (day)−1) and GnRH antagonist (150 μg/day, Detirelix). Treatment with GnRH antagonist suppressed gonadotropin and testosterone production, reduced the weights of testes, epididymides and seminal vesicles, and inhibited germ cell development. Flutamide administration markedly elevated serum and pituitary levels of gonadotropins as well as serum and testicular androgen concentrations. Casodex-induced elevation of gonadotropin concentrations was less pronounced and serum and testicular levels of androgens did not change significantly. The reduction of seminal vesicle weights was similar after Casodex and GnRH antagonist treatment, whereas flutamide was less effective. Testicular weight and spermatogenesis (assessed by light microscopical and flow-cytometric analysis) remained unaffected by Casodex and flutamide. It is concluded, that 1. Casodex, in contrast to flutamide, is a peripherally selective antiandrogen, and 2. Casodex influences release of gonadotropins into circulation less than flutamide. Therefore this antiandrogen might be useful clinically for selectively blocking androgen actions in the accessory sex glands.
Dehydration, but not vasopressin infusion, enhances the adrenocortical responses of sheep to corticotropin-releasing hormone or restraint
Authors: Matthews S. G. , Parrott R. F.
Published: June 2009

Two experiments were carried out using adult castrated sheep prepared with jugular vein catheters. In Experiment 1, sheep (N=8) were injected iv with saline vehicle, vehicle + 15 or 30 μg oCRH, or subjected to 120 min mild physical stress (restraint), following a 48 h period during which water was freely available or withheld. Blood samples were taken for 30 min before and 120 min after oCRH injection, and before and during restraint, and the plasma analysed for AVP and cortisol content. Levels of AVP increased by over 500% after dehydration, but were unaffected by oCRH or restraint. In contrast, plasma cortisol was unchanged after dehydration, but increased after oCRH and restraint. Moreover, these cortisol responses were significantly greater when the sheep were dehydrated. In Experiment 2, euhydrated sheep (N =6) were infused iv with saline vehicle or vehicle + AVP for a 5-h pretreatment period, followed by a 2-h experimental period in which the animals were injected with 15 μg oCRH or subjected to 120 min restraint, as in Experiment 1. Blood samples were taken throughout the experiment from a contralateral catheter and the plasma analysed for AVP and cortisol content. The AVP infusion produced plasma levels of the hormone approximately twice those seen after 48 h dehydration in Experiment 1, but did not affect cortisol secretion. Furthermore, the cortisol response to oCRH, or restraint, was not enhanced by the AVP infusion. These results suggest that pituitary responsiveness to exogenous or endogenous CRH (restraint stress) may be enhanced in sheep by dehydration through a mechanism that does not involve an adrenal or pituitary action of circulating AVP.
The gonadotropin-releasing hormone agonist leuprolide affects the thymus and other non-reproductive systems of female rats
Authors: Blacker Charla M. , Ataya Khalid M. , Savoy-Moore Ruth T. , Subramanian Marappa G. , Mutchnick Milton G. , Dunbar Joseph C.
Published: June 2009

To evaluate the effects of a gonadotropin-releasing hormone agonist on non-reproductive systems, we administered [D-Leu 6, Des-gly 10]-GnRH ethylamide (leuprolide; 5 μg/day) for 21 days to female Sprague-Dawley rats. In Experiment 1, continuous infusion (Alzet minipumps sc) was compared to injection. Increased thymus and body weights and decreased estradiol and uterine weights were noted for both administration methods. Spleen weight increased only in rats treated by continuous infusion. Ovary, kidney and liver weights did not change. Only leuprolide-injected rats had elevated LH with decreased corticosterone and ACTH levels, possibly related to the injection process. Glucose, insulin, progesterone, FSH and corticosterone/ACTH were not different. In Experiment 2, intact and ovariectomized rats were implanted with minipumps delivering leuprolide or 0.9% NaCl. Body and thymus weights increased, whereas uterine weight and estradiol declined in both leuprolide-treated and ovariectomized rats. No synergism between leuprolide and ovariectomy was noted. Thymosin α1, but not thymosin β4, increased in leuprolide-treated ovariectomized rats. Peripheral white blood cell count was elevated in leuprolide-treated intact rats and ovariectomized rats. In bone marrow, non-nucleated cell count declined in leuprolide-treated intact rats, contributing to the decreased total cell count in this group. Nucleated cell count was unaffected. Therefore, thymus weight gain was accompanied only in some cases by functional changes. Our results demonstrate that leuprolide affects non-reproductive systems, in a similar manner to ovariectomy. We suggest that such alterations may be due to the hypoestrogenic environment produced by leuprolide.
Renotropic and gonadotropic activity in homologous and heterologous hybrids of ovine luteinizing hormone and human chorionic gonadotropin subunits
Authors: Nomura Kaoru , Nakamura Yasunori , Ujihara Makoto , Ohmura Kazutaka , Toraya Shohzou , Horiba Nobuo , Demura Hiroshi
Published: June 2009

We previously demonstrated the renotropic activity of ovine and porcine LH, i.e. the stimulation of [3H]thymidine incorporation into the renal DNA of castrated hypophysectomized rats. We conducted this study to determine which condition is required to promote renotropic activity. We prepared homologous (oLHα· oLHβ, hCGα·hCGβ) and heterologous (oLHα·hCGβ, hCGα·oLHβ) hybrids from isolated oLH- and/or hCG-derived subunits. Native oLH and all hybrids showed gonadotropic activity when examined for cyclic AMP generation in cultured Leydig tumour cells (MA-10). Native oLH and the hybrids which showed renotropic activity were all found to contain at least one of the oLH subunits. Our findings point out the important, special role of oLH subunits in promoting renotropic activity. The condition required is suggested to be presence of a common structure in the two oLH subunits. Such a structure should consequently not be present in hCG. A carbohydrate moiety of oLH containing a sulphate group is proposed as a candidate, but the assumption remains to be demonstrated.
Evidence for direct non-genomic effects of triiodothyronine on bone rudiments in rats: Stimulation of the inositol phosphate second messenger system
Authors: Lakatos Peter , Stern Paula H.
Published: June 2009

Thyroid hormones increase cytosolic free calcium by binding to plasma membrane receptors in several tissues. This calcium increase appears to initiate extranuclear effects in these tissues. Increases in cytosolic calcium are often a consequence of stimulation of inositol phosphate second messenger pathway. Several calcemic hormones act via this signal transduction route. Therefore we investigated the effects of the metabolically active T3 and the inactive analogues 3,5-diiodotyrosine and rT3 on the inositol phosphate pathway in fetal rat limb bone cultures prelabeled with [3H]myoinositol. Labelled inositol and inositol phosphates were separated by HPLC. There was a significant increase in the radioactivity in inositol bis- and trisphosphates after 1 min of exposure to 10−7 mol/l T3. Stimulation was also observed at 10−6 mol/l T3, but not at 10−5 mol/l. Time course studies demonstrated a rapid effect of T3 on inositol phosphates within 30 seconds that lasted through 5 min. After 20 min incubation with T3, no increase was observed in inositol mono- and bisphosphates, and a decrease was seen in inositol trisphosphate. Pretreatment with indomethacin prevented these effects of T3. 3,5-diiodothyrosine and rT3 did not affect inositol phosphate metabolism. These results suggest the existence of plasma membrane-associated receptors for T3 in bone, in addition to the nuclear receptors demonstrated previously. The role of these receptors in the effects of thyroid hormones on bone remains to be established.
Increased serum concentrations of type I procollagen C-terminal propeptide and osteocalcin during a short course of calcitriol administration to adult male volunteers
Authors: Gram Jeppe , Bollerslev Jens , Nielsen Henning K. , Junker Peter
Published: June 2009

To investigate bone collagen metabolism during vitamin D treatment, 15 healthy males (aged 28-45 years, median 34) were treated orally with calcitriol, 2 μg daily for 7 days and followed for a total of 2 weeks. The serum concentration of calcitriol rose markedly (median difference and 95% confidence limits: 49% (5-82), p<0.005) during treatment, whereas serum levels of calcidiol, and calcium remained unchanged. The serum level of procollagen type I C-terminal propeptide rose 15% (7-33, p<0.003), whereas no alterations were observed concerning serum procollagen type III N-terminal propeptide, and serum hyaluronan. The serum concentration of osteocalcin rose concomitantly (26% (12-45), p<0.003). All values returned to baseline levels within seven days after the treatment week. The serum levels of osteocalcin and procollagen type I C-terminal propeptide were positively correlated (rs=0.71, p<0.004) during the study. Serum procollagen type I C-terminal propeptide and serum osteocalcin did not correlate with serum procollagen type III N-terminal propeptide or serum hyaluronan either at baseline or after treatment. It is concluded that a short course of calcitriol administration to healthy males stimulates the biosynthesis of bone-related matrix proteins. By contrast, connective tissue components of predominantly extraosseous origin are not affected.
LH pulsatility and in vitro bioactivity in women with anorexia nervosa-related hypothalamic amenorrhea
Authors: Allouche Jacques , Bennet Antoine , Barbe Pierre , Plantavid Monique , Caron Philippe , Louvet Jean-Pierre
Published: June 2009

LH nocturnal pulsatility and bioactivity to immunoreactivity (B/I) ratio were determined in 16 patients with anorexia nervosa-related hypothalamic amenorrhea and low sex steroid levels, and in 12 normal women in the midfollicular phase. The patients were subdivided into 2 groups: IA (N=7) without, and IB (N=9) with documented recent weight gain. Blood samples were taken from each subject at 10-min intervals from 00.00 to 06.00 h. Immunoreactive LH data were analysed with cluster analysis algorithm. A pool of aliquots from all the samples was used to evaluate bioactive LH, immunoreactive LH and LH B/I ratio in each subject. LH pulse frequency was lower in Group IA than in controls, whereas it did not differ significantly between Group IB and controls. LH pulse amplitude was lower in Group IA, and higher in Group IB than in controls. LH B/I ratio was below the control range in 3/16 patients. In conclusion, persistent hypothalamic amenorrhea does not require a permanent inhibition of the GnRH pulse generator; transient inhibition of pulsatility and qualitative abnormalities of gonadotropins could be involved in the mechanism, at least in some patients.
Basal prolactin and total lactogenic hormone levels by microbioassay and immunoassay in normal human sera
Authors: Maddox Paul R. , Jones Derek L. , Mansel Robert E.
Published: June 2009

The availability of an improved microbioassay for prolactin measurement has enabled comparison of lactogenic hormone bioactivity and immunoactivity in normal human serum. Serum was studied from 61 normal females and 15 normal males. The correlation of both assays was very close for all subjects with a mean ratio of bioassay to immunoassay of 1.5 (range 0.8-2.0) for prolactin and 1.4 (range 0.5-1.9) for total lactogenic hormone. There was no significant variation in prolactin or total lactogenic hormone values by microbioassay or immunoassay with sexual or menstrual status. Postmenopausal prolactin levels were lower by both assays compared with premenopausal values with a relative and absolute decrease in prolactin bioactivity with age. These findings indicate that there is a good correlation between prolactin bioactivity and immunoactivity in human serum.
Dynamics of the acute effects of octreotide, bromocriptine and both drugs in combination on growth hormone secretion in acromegaly
Authors: Wagenaar Annie H. , Harris Alan G. , van der Lely Aart J. , Lamberts Steven W. J.
Published: June 2009

The separate and combined GH-lowering effects of single doses of octreotide and bromocriptine were assessed in 51 acromegalic patients on 4 occasions each 2 days apart. Patients received sequentially: placebo sc (N=51), 50 μg octreotide sc (N=51), 2.5 mg bromocriptine po (N=40) or a combination of both drugs (N=25). With octreotide, in 28 patients (55%) GH levels were suppressed to less than 5 μg/l and 39 of them (76.5%) had a 50% or greater decrease of their basal GH level from 2 to 6 h. During bromocriptine, GH values were suppressed to below 5 μg/l in 11 patients (27.5%) and reduced by 50% or more in 21 (52.5%). The combination of both drugs acutely suppressed GH levels to less than 2 μg/l in 32%, to less than 5 μg/l in 56%, and by more than 50% in 84% of patients. Octreotide produced a stronger and faster suppression of GH levels than bromocriptine in most patients. The combination of both drugs had an additive effect on the lowering of GH levels, especially between 7 and 10 h after drug administration. These results suggest that chronic therapy with a combination of both drugs may be as effective as therapy with higher doses of either compound alone. Albeit transient, octreotide caused a rapid near total suppression of insulin release in the morning, 15 to 45 min after administration. Postprandial glucose rise, between 2 and 3.5 h after breakfast was significantly higher during octreotide than on the control day.
Prediction of relapse in drug-treated Graves' disease using thyroid stimulation indices
Authors: Ikenoue Hiroshi , Okamura Ken , Sato Kaori , Kuroda Takeo , Yoshinari Mototaka , Tokuyama Takashi , Nakagawa Mizuho , Fujishima Masatoshi
Published: June 2009

Thyroid stimulation indices such as high thyroidal radioactive iodine uptake, increased estimated thyroid weight, presence of TSH-binding inhibitor immunoglobulin or thyroid-stimulating antibody, and elevated serum thyroglobulin level, were evaluated in 148 patients with Graves' disease who had been treated with antithyroid drugs for two years or more before the drugs were withdrawn. In all 19 patients in whom three or more indices were positive, early relapse, within 12 months, occurred after reducing the dosage of antithyroid drugs. Other 129 patients were followed after the drug was withdrawn and in 77 patients with one or two positive indices, early relapse occurred in 65-71% and late relapse, after 12 months or later, occurred in 2-11%. In 52 patients in whom none of the indices were positive, 86% remained in remission, but 10% developed an early relapse, and 4% a late relapse. We conclude that a combined analysis of thyroid stimulation indices is useful in predicting relapse in Graves' disease whereas it remains difficult to predict permanent remission.
Course of thyroid iodine concentration during treatment of endemic goitre with iodine and a combination of iodine and levothyroxine
Authors: Saller Bernhard , Hoermann Rudolf , Ritter Michael M. , Morell Roland , Kreisig Torsten , Mann Klaus
Published: June 2009

In the treatment of endemic goitre, the concept of giving levothyroxine in combination with iodine offers a promising therapeutic approach by influencing not only TSH secretion but also intrathyroidal iodine content. However, little is known about the doses of iodine necessary to correct intrathyroidal iodine deficiency. To get more information on this important issue, we conducted a prospective, double-blind study on the effect of a monotherapy with 500 μg iodide/day and a combined treatment with 100 μg levothyroxine and 100 μg iodide/day on thyroid iodine concentration as measured by fluorescence scintigraphy. In a group of 12 patients, a 4-month treatment with 100 μg levothyroxine and 100 μg iodide/day did not significantly affect thyroid iodine concentration (0.35±0.14 vs 0.37±0.11 mg/g). The application of 500 μg iodide/day in these patients during a second 4-month period resulted in a sharp increase in thyroid iodine concentration from 0.37±0.11 to 0.61±0.14 mg/g (p<0.01). Another group of 8 patients first treated with 500 μg iodide/day also showed a significant increase in iodine concentration from 0.35±0.14 to 0.65±0.20 mg/g (p<0.01). After switching to the combination regimen during a second 4-month period, thyroid iodine concentration slightly decreased, particularly in those patients with high iodine concentrations after monotherapy with iodide (0.65±0.20 vs 0.50±0.12 mg/g, p<0.05). In conclusion, treatment with 500 μg iodide/day could sharply increase thyroid iodine concentration in patients with endemic goitre. In contrast, a combination of 100 μg levothyroxine and 100 μg iodide/day had no significant effect on thyroid iodine concentration.
Amiodarone and thyroid hormone metabolism in the rat heart
Authors: Gøtzsche Liv S. Bjørn-Hansen , Boye Niels
Published: June 2009

The effect of amiodarone on thyroid hormone metabolism in heart, muscle, liver and kidney was investigated. Rats were treated ip with a high (100 mg · kg−1 · day−1) or a low (50 mg · kg−1 · day−1) dose of amiodarone for 10 days. Serum T3 was dose-dependently depressed (mean 30 and 54% of controls, respectively, p<0.01). rT3 was elevated (to 663 and 313% of controls, p<0.01 and 0.05, respectively). Serum T4 was depressed only in the high-dose group (to mean 80%, p<0.05). Tissue concentrations of T3 in the heart and muscle from treated animals did not differ from controls, whereas liver and kidney T3 contents were markedly reduced in both groups (p<0.05). Heart T4 and rT3 were elevated to about 200% of controls (p<0.01 and 0.05, respectively). The same pattern was observed in the other tissues. Iodothyronine-5'-monodeiodinase activity was significantly depressed in all tissues; heart: 32 and 28% of controls (p<0.05); muscle: 36 and 49% (p<0.01); liver: 11 and 13% (p<0.01); kidney: 22 and 28% (p<0.01), respectively. In conclusion, amiodarone depresses iodothyronine-5'-monodeiodinase activity in the heart, muscle, liver and kidney in a dose-dependent manner, resulting in lowered T3 concentrations in the liver and kidney, whereas no reduction of tissue T3 content is observed in the heart and muscle. This may indicate that T3 from plasma may cross the cardiac sarcolemma without hindrance.
Adrenergic mediation of the naloxone-induced GnRH release from hypothalami of ovariectomized, steroid-treated immature rats
Authors: Kim K. , Lee B. J. , Lee C. C. , Cho W. K. , Ramirez V. D.
Published: June 2009

The present study examines the effect of naloxone on GnRH release in vitro under different steroid milieus. Naloxone (6.1 μmol/kg) administered 30 min before decapitation was highly effective in evoking GnRH release from superfused hypothalamic tissues derived from ovariectomized, estradiol- and progesteronetreated immature rats, while ineffective in altering GnRH release from intact, ovariectomized and vehicle- or estradiol-treated rats. To further explore the possible involvement of catecholamines in the naloxone-stimulated GnRH release, diethyldithiocarbamic acid (2.9 mmol/kg), an inhibitor of noradrenalin synthesis, was administered ip 30 min before naloxone injection into ovariectomized, estradiol- and progesterone-treated rats. Diethyldithiocarbamic acid markedly reduced the naloxone-evoked GnRH release, although it was ineffective in modifying the spontaneous release of GnRH. A blockade of α-adrenergic receptor with phenoxybenzamine significantly suppressed the naloxone-stimulated GnRH release, whereas treatment with propranolol, a β-adrenergic receptor blocker, failed to alter GnRH release. The present data suggest that the endogenous opioid peptide may participate in the regulation of GnRH release under a particular steroid milieu, and the inhibitory action of endogenous opioid peptide seems to require the mediation of adrenergic neurotransmission, presumably through α-adrenergic receptor.
CD4+CD45RA+ cells (suppressor-inducer T cells) in thyroid tissue from patients with Graves' disease
Authors: Kawakami A. , Eguchi K. , Matsunaga M. , Tezuka H. , Ueki Y. , Shimomura C. , Otsubo T. , Nakao H. , Migita K. , Ishikawa N. , Ito K. , Nagataki S.
Published: June 2009

Previously, we used dual immunofluorescent analysis and showed that the thyroid gland from patients with Graves' disease had a reduced number of CD4+CD45RA+ cells, but an increased number of complementary CD4+CDw29+ cells. An immunohistochemical study, however, produced opposite results; interstitial lymphocytes predominantly expressed the CD45RA+ rather than the CDw29+ phenotype. Because the difference in findings may be due to differences in the techniques used, we did the following experiments: Mononuclear cells were treated with various amounts of collagenase (50-1000 mg/l) which had no effect on the cell surface antigens CD3, CD4 and CD45RA. A dual immunofluoresent study showed that the numbers of CD4+CD45RA+ and CD8+CD45RA+ cell population among CD45RA+ cell population were markedly decreased in the thyroid tissue, and that the CD45RA antigen on the intrathyroidal mononuclear cells was mainly expressed on the CD20+ cells. As the thyroid section had been fixed with acetone before immunohistochemical staining, CD45RA− cells were treated with acetone and stained with anti-CD45RA monoclonal antibody using an avidin-biotin peroxidase complex method. The results of this experiment suggest that there are cell surface molecules which react with anti-CD45RA monoclonal antibody after treatment with acetone in CD45RA− cells. The above findings confirm our previous results which showed that the thyroid glands of patients with Graves' disease have decreased numbers of suppressor-inducer T cells. Also, several problems exist in the detection of CD45RA+ cells when using an immunohistochemical method.
Regulation of atrial natriuretic hormone production by triiodothyronine in cultured rat atrial myocytes
Authors: Mori Yasukiyo , Nishikawa Mitsushige , Matsubara Hiroaki , Toyoda Nagaoki , Masaki Hiroya , Yonemoto Toshinaga , Takagi Tomoyuki , Inada Mitsuo
Published: June 2009

Since thyroid hormones have been reported to increase the synthesis of rat atrial natriuretic hormone and its mRNA accumulation, we further investigated the mechanism of stimulation of rANH synthesis by T3 using cultured rat atrial myocytes. T3 (10−9-10−7 mol/l) increased cellular content and secretion into the medium of immunoreactive rANH in a dose-dependent manner. However, the ratio of secreted/cellular rANH was not altered by the addition of T3. Furthermore, in both cellular and secreted rANH, the larger molecular form (γ-rANH) apparently predominated over the smaller one (α-rANH), and this profile was not influenced by T3 (10−7 mol/l). Although T3 (10−9-10−7 mol/l) also increased cellular rANH mRNA accumulation, the ratio of cellular rANH/rANH mRNA was not changed. Moreover, using actinomycin D, we found that T3 (10−7 mol/l) did not affect the degradation of rANH mRNA. From these findings, we suggest that T3 has no specific effects on the translational and posttranslational processes and the release of rANH, but that T3 stimulates rANH synthesis in the pretranslational levels, probably in the transcriptional level of rANH gene.