bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of long-term iodide refeeding on the synthesis and secretion of T3, T4 and TSH in severe iodine deficient rats
Authors: Rognoni J. B. , Lemarchand-Béraud T. , Berthier C. , Simon C. 
Published: December 2008

Abstract.
For 6 months, male Wistar rats received an iodine deficient diet (LID), with propylthiouracil (PTU) for the last 2 months. At the end of this treatment (day 0), a daily iodide intake of 20 μg (group 20) and 50 μg (group 50) was supplied. Synthesis and secretion of T3, T4 and TSH as well as thyroid and serum PBI were studied during 140 days of iodine repletion.
For the first 4 days of iodide refeeding, thyroid PBI remained low (0.4 ± 0.2 μg 127I/gland) whilst T3 and T4 were undetectable during 2 days only. Thereafter, these parameters increased regularly, reaching control values on days 80, 16 and 90, respectively. During 2 weeks, the thyroid T3/T4 ratio was 6-fold higher and reached the control value on day 45. Plasma T3 and T4 levels were low, but measurable for the first 4 days (0.5 ± 0.1 and 9.9 ± 2.6 nm, respectively). T3 rapidly reached a normal level on day 8, inducing a high plasma T3/T4 ratio for 16 days. This ratio decreased abruptly when T4 secretion increased, attaining the control value on day 45. Therefore, the preferential T3 secretion occurring during the first 16 days is directly linked to the preferential T3 synthesis. Plasma TSH levels remained 10-fold higher than the control value for the first 8 days (490 ± 99 vs 39 ± 15 μU/ml), then decreased abruptly and reached normal level after 1 month. Pituitary TSH contents varied in an opposite manner to the plasma TSH concentrations.
In conclusion, the effect of iodide on thyroid function occurs sequentially, i.e. thyroid hormone synthesis precedes neosecretion (latency phase). In both processes, T3 appears preferentially. This phenomenon is linked to the low thyroglobulin (Tg) iodination rate. In addition, the re-establishment of a normal thyroid hormone secretion prevailing over the iodinated Tg store constitution represents an adaptative mechanism; this leads rapidly to a maximum supply of active hormone (T3) with iodine economy. Moreover, it takes 2–3 months for the complete thyroid function restoration. At the pituitary level, the normal plasma T3 concentration found during the latency phase of iodide refeeding is not sufficient by itself to inhibit TSH secretion. This parameter starts to decrease only when T4 has reached a critical level to generate adequate T3 from T4 deiodination. Inhibition of TSH synthesis is a less sensitive process since it occurs for more elevated T4 concentrations. Finally, the similar pattern of thyroid function's recovery in the two groups indicates that the 20 μg dose is a sufficient supply and that thyroid autoregulation occurs, thus avoiding a thyroid hyperfunction.
Contribution from local conversion of thyroxine to 3,5,3'-triiodothyronine to intracellular 3,5,3'-triiodothyronine in several organs in hypothyroid rats at isotope equilibrium
Authors: van Doom J. , Roelfsema F. , van der Heide D. 
Published: December 2008

Abstract.
The intracellular conversion of T4 to T3 was investigated in various tissues of hypothyroid rats after continuous iv infusion of radiolabelled T3 and T4. Two groups of 4 thyroidectomized rats were infused with carrier-free 125I-labelled T4 as well as 131I-labelled T3 until isotope equilibrium was achieved. Plasma, various tissue homogenates (liver, kidney, pituitary, thigh muscle, cerebral cortex and cerebellum) and subcellular fractions (nuclei, mitochondria, microsomes, cytoplasm) from liver, kidney and the pituitary gland were extracted for thin layer chromatography.
The [125I]T3/[131I]T3 ratios were determined and the extra contribution of [125I]T3 derived from local conversion of [125I]T4 to the total [125I]T3 was calculated in percent.
In addition to the [125I]T3 derived from plasma, [125I]T3 derived from locally converted [125I]T4 was present in all tissues investigated. There was substantially more, although in varying quantities, in the cerebral cortex (79 ± 2%), the cerebellum (68 ± 4%) and the pituitary gland (53 ± 1%) than in the liver (10 ± 6%), the kidney (11 ± 5%) and thigh muscle (17 ± 6%); in the latter tissues most of the 125I-labelled T3 is derived directly from plasma.
These results indicate that in the brain of severe hypothyroid rats there is pronounced conversion of T4 to T3 and effective binding of the T3 produced whereas the T3 in the liver, kidney, and muscle is predominantly derived from plasma. At the intracellular level, within the investigated tissues, the locally formed T3 was distributed equally over the subcellular fractions.
Regulation of parathyroid hormone release in primary and secondary hyperparathyroidism studies in vivo and in vitro
Authors: Rudberg C. , Åkerström G. , Ljunghall S. , Grimelius L. , Johansson H. , Pertoft H. , Wide L. 
Published: December 2008

Abstract.
The effects of calcium on parathyroid hormone (PTH) release were studied in vivo and in vitro in primary hyperparathyroidism (HPT) and in vitro in secondary HPT. In vivo the serum PTH was clearly reduced by intravenous calcium infusion in all the examined patients with primary HPT caused by adenoma. In vitro the release of PTH from dispersed parathyroid cells was likewise suppressed by raising the calcium concentrations in the incubation media, though in all cases a basal release of PTH still persisted even at high calcium concentrations. The degree of suppressibility in vitro varied, but in both primary HPT with adenoma and in secondary HPT it was inversely related to the patients' serum calcium values. These results suggest that the secretion of PTH in patients with primary and secondary HPT is not autonomous either in vivo or in vitro. Furthermore, the non-suppressible basal release of PTH indicates that a major cause for the increased secretion of PTH is the increased number of parenchymal cells. However, the degree of suppressibility of the individual cells rather than the absolute number of cells, seems to be of great importance for the individual serum calcium values in HPT.
Circadian rhythm of catecholamines, cortisol and prolactin is altered in patients with apallic syndrome in comparison with normal volunteers
Authors: Ratge Dieter , Knoll Ernst , Diener Ulrich , Hadjidimos Alexander , Wisser Hermann 
Published: December 2008

Abstract.
Circadian rhythms of catecholamines, cortisol and prolactin were investigated in 4 healthy subjects and in 6 patients suffering from an apallic syndrome. The clinical picture of this syndrome is characterized by disturbed consciousness (coma vigile), suspension of the sleeping and waking rhythm, lack of emotional reactions and appearance of primitive motor patterns. With the exception of dopamine a pronounced circadian rhythm was found in the control group for all investigated parameters. Catecholamines and cortisol showed a good correlation in the temporal pattern of plasma concentrations and urinary excreted amounts. In all apallic patients the circadian rhythm of prolactin was abolished. Only in one patient a rhythm of catecholamines and in 2 patients a rhythm of cortisol was still detectable. The data may indicate that the episodic nature of hormone secretion was essentially unaffected by the apallic syndrome. These results are regarded as an indication that endogenous, centrally controlled processes participate in circadian rhythms.
Central role of angiotensin in the hyperosmolality- and hypovolaemia-induced vasopressin release in conscious rats
Authors: Yamaguchi K. , Sakaguchi T. , Kamoi K. 
Published: December 2008

Abstract.
To evaluate a central role of angiotensin in vasopressin (ADH) release in response to hyperosmolality or hypovolaemia, we examined in conscious rats the effects of intraperitoneal (ip) injections of 2 ml/100 g body weight of hypertonic saline or polyethylene glycol (PEG; 250 mg/ml of 145 mM NaCl) on plasma ADH and angiotensin II (AII) levels and of intracerebroventricular (icv) administrations of Sar1-Ala8-AII (a competitive receptor blocker for AII) on the plasma ADH responses to the ip injections. Thirty min after ip injections of 900 mm NaCl, plasma ADH, osmolality and sodium increased with unchanged plasma AII and with reduced haematocrit. Two h after ip administrations of PEG, plasma ADH, AII and haematocrit were augmented with un-altered plasma osmolality and sodium. The responses of plasma ADH to ip injections of 900 mM NaCl and PEG were significantly inhibited (P < 0.05) by 1 μg of Sar1-Ala8-AII injected icv 5 min before blood samplings which had no appreciable effect on plasma osmolality, electrolytes and haematocrit. Based on these results, we concluded that angiotensin may participate in both the hyperosmolality- and hypovolaemia-induced ADH secretion by acting on the central nervous system.
Lack of influence of the antidopaminergic drug domperidone on basal and TRH-stimulated TSH-serum levels after oral administration
Authors: Wenzel K. W. , Döring J. 
Published: December 2008

Abstract.
Since antidopaminergic drugs are known to elevate basal and TRH-stimulated TSH-serum levels and since this effect was also shown after iv administration of the novel dopamine antagonistic agent domperidone, it was investigated, whether this antiemetic drug could interfere after oral intake with the evaluation of thyroid function. Oral domperidone caused a marked TSH-enhancement of TRH-induced TSH increments in 6 out of 14 euthyroid subjects, with no statistical significance, however. The difference between oral and parenteral influence as well as inter-individual changes are probably due to the varying first pass effect of the drug after oral absorption.
Regulation of somatotrophic and lactogenic binding sites in mouse liver membranes
Authors: Sasaki Norio , Imai Yasuo , Tsushima Toshio , Matsuzaki Fukashi 
Published: December 2008

Abstract.
Both somatotrophic and lactogenic binding sites increase markedly in pregnant mouse liver membranes. The regulatory mechanisms of these binding sites involved in pregnancy are studied. The study of the effects of various hormone administration to female mice reveals that oestradiol increases and testosterone decreases lactogenic binding sites, and that other hormones affect neither somatotrophic nor lactogenic binding sites. Hysterectomy, adrenalectomy or foetectomy of pregnant mice cause a remarkable reduction of somatotrophic binding sites to the level observed in non-pregnant or post-partum animals. In contrast, the lactogenic binding sites are not influenced by these treatments. Replacement with corticosterone after adrenalectomy does not prevent the decrease of somatotrophic binding sites. The contents of placental lactogen from both adrenalectomized and foetectomized pregnant mice are similar to those of the normal pregnant group. These observations indicate that the regulatory mechanisms modulating somatotrophic and lactogenic binding activities are quite different and that increased somatotrophic binding sites during pregnancy are supported by the factor(s) generated in the foeto-placental unit and maternal adrenal gland.
Oestrogens, gonadotrophins and SHBG during oral and cutaneous administration of oestradiol-17β to menopausal women
Authors: Fåhraeus Lars , Larsson-Cohn Ulf 
Published: December 2008

Abstract.
Thirty-eight post-menopausal women were randomly allocated to 6 months of treatment with either 2–4 mg of micronized oestradiol-17β taken orally or 3 mg of oestradiol-17β applied cutaneously. The plasma concentrations of oestrone, oestradiol, LH, FSH and sex hormone binding globulin (SHBG) were determined twice before and after 2,4 and 6 months of treatment.
In both groups the clinical effects were satisfactory. During treatment the mean oestradiol levels showed similar increases in the two groups while the oestrone concentration was markedly raised only among those taking oestradiol orally. The mean LH and FSH concentrations were significantly lowered in both groups. SHBG was increased with both treatments although more marked in the group on oral medication. Doubling of the oral dose from 2 mg to 4 mg gave significant changes of the LH, FSH and oestrone concentrations.
Thus, in the given doses, the two routes of administration seemed to have similar effects on post-menopausal symptoms and on the plasma concentrations of gonadotrophins and oestradiol. However the plasma oestrone and SHBG levels became significantly higher during the oral than during the cutaneous treatment.
Comparison between the progestin secretion responsiveness to gonadotrophins of rat cumulus and mural granulosa cells in vitro
Authors: Magnusson C. , Billig H. , Eneroth P. , Roos P. , Hillensjö T. 
Published: December 2008

Abstract.
Several studies have shown differences in gonadotrophin receptor content between different granulosa cell (gc) populations within the ovarian follicle, but little is known about the gonadotrophin sensitivity in gc from different parts of the follicle. This study is an investigation of progestin synthesis and responsiveness to highly purified human and partly purified rat gonadotrophins. It involves short-term culture of rat cumulus and mural gc obtained from preovulatory follicles of PMSG-treated immature rats. The responsiveness to FSH in terms of progestin accumulation was similar in the two gc populations, whereas the responsiveness to LH was greater in the mural gc than in the cumulus. The morphological response in the cumulus cells (mucification) correlated with the steroidogenic response. The pattern of progestin synthesis differed between the two gc populations. In the cumulus gc progesterone was dominant, whereas 20α-dihydroprogesterone was the main progestin secreted in the mural gc. The difference in responsiveness to gonadotrophins correlates well with the reported differences in receptor content in the two gc populations.
Radioimmunological determination of somatomedin B in healthy children and in children with growth disturbances
Authors: Wirth S. , Schönberger W. , Roth A. , Grimm W. 
Published: December 2008

Abstract.
Serum somatomedin B levels were determined by radioimmunoassay in 209 healthy boys and girls from one month to 16 years of age.
Low values were found up to the second year life. In the first year the mean level was 13.8 mg/l in girls and 11.5 mg/l in boys. In older children the values increased to levels between 13 and 22 mg/l in boys and between 13 and 18.5 mg/l in girls. They were independent of the stage of pubertal development.
Somatomedin B levels were normal in 71 children with constitutional growth delay, primordial dwarfism, familial dwarfism and other forms of growth disturbance. The mean levels were between 12.1 and 14.4 mg/l.
Values below 6 mg/l were present only in children with hGH deficiency. In these patients we could find an increase of the mean level from 4.3 mg/l without therapy to 9.4 mg/l under treatment.
Thus the determination of somatomedin B seems to be useful for the diagnosis of hGH deficiency.
Properdin factor B (Bf) and glyoxalase in Graves' disease
Authors: Allannic H. , Fauchet R. , Lorcy Y. , Phengsavath H. , Gueguen M. , Knoi T. D. , Genetet B. , Le Gall J. Y. 
Published: December 2008

Abstract.
Patients with Graves' disease were phenotyped for properdin factor B (Bf) and glyoxalase, which are coded for by genes mapping close to the HLA region on the sixth chromosome. Frequency data were analysed in relation to HLA-A, -B and -DR typing data. Diagnosis of Graves' disease was based on the usual criteria including elevated T3 and T4 levels and free T4 index and a homogenous thyroid scan. Ninety-four patients with Graves' disease were phenotyped for properdin factor B (Bf) and 37 for red cells glyoxalase (GLO). HLA-A, -B and -DR antigens were typed in 94 patients using a lymphocyte microcytotoxicity assay. The frequency distribution of Bf and GLO alleles showed no significant differences from control subjects. This finding contrasts with the reports of an increased frequency of Bf Fl in insulin-dependent diabetes mellitus. The difference in the two diseases which are both associated with an increased frequency of the antigen combination D8-DR3, is accounted for by linkage disequilibrium between B 18 and BfF1.
Inhibitory effect of cyproheptadine on ACTH secretion in patients with Addison's disease
Authors: Loli P. , Frascatani F. , Gelli D. , Maggioni M. , Muratori F. , Ronzoni M. 
Published: December 2008

Abstract.
In 14 patients with Addison's disease plasma levels of ACTH were studied after administration of a single oral dose (16 mg) of cyproheptadine.
The drug administration was followed by an inhibition of ACTH release.
These results support the view that cyproheptadine may exert an inhibitory effect on ACTH secretion in subjects whose corticosteroid feedback mechanism is normal.
We hypothesize that the effect of cyproheptadine might be related to its anti-serotonin or anti-histaminergic action.
Changes in the responsiveness of adrenal cells from foetal goats at different times during pregnancy
Authors: Challis John R. G. , Currie W. Bruce 
Published: December 2008

Abstract.
To understand the factors responsible for the increased pre-partum output of cortisol from the adrenal glands of the goat foetus, we measured changes in responsiveness to ACTH in vitro of dispersed adrenal cells from foetal goats of various gestational ages and we determined the output of cortisol (F) and corticosterone (B) in the presence of exogenous progesterone (P4) and 17α-hydroxyprogesterone (17α-OHP4). The increment in F output after ACTH increased 5-fold between day 100 and days 147 or 154 (term). This increase was not associated with changes in the ED50 for ACTH stimulation of F output. The basal and ACTH-stimulated output of F was similar to that of B at day 100 but 5–7 times greater than that of B at day 154. There was a significant effect of ACTH on P4 output on days 77, 100 and 147 but net utilization of P4 by the cells at term. The ratio of exogenous P4: 17α-OHP4 converted to F varied with gestation and increased from 0.11 at day 100 to 0.99 at day 154. Exogenous P4 was converted to B at all stages of pregnancy.
We conclude that in the goat there is an increase in the responsiveness of foetal adrenal cells to ACTH between day 100 of gestation and term. One factor associated with this change in adrenal responsiveness may be an increase in the activity of the enzyme 17α-hydroxylase.
Regulation of inhibin secretion by Sertoli cell-enriched cultures
Authors: Verhoeven G. , Franchimont P. 
Published: December 2008

Abstract.
Sertoli cells secrete a factor which has the same bioactivity as ovine testicular lymph inhibin: it selectively suppresses the secretion of FSH by cultured pituitary cells. We investigated the factors that acutely modulate the secretion of this inhibin by cultured Sertoli cells derived from immature rats. The secretion of inhibin was studied on day 7 of culture after a 24 h period of incubation in the presence or absence of steroids, gonadotrophins and foetal bovine serum, added alone or in various combinations. It could be demonstrated that aromatisable as well as non-aromatisable natural and synthetic androgens promote the secretion of inhibin in a dose-dependent way. FSH and pregnant mare serum gonadotrophin — at concentrations that clearly stimulate Sertoli cell aromatase activity — did not affect basal or androgen-stimulated production of inhibin. hCG was equally uneffective. The effect of androgens was not modified by the addition of an aromatase inhibitor but it was neutralized by the antiandrogen cyproterone acetate. Oestradiol-17β did not influence the secretion of inhibin whereas progesterone decreased it.
Serum enhanced basal as well as androgen stimulated secretion of inhibin. It is concluded that androgens are the major factor which acutely stimulates the production of Sertoli cell inhibin.
Endocrine expressions of hydrocephalus
Authors: Caporal R. , Segrestaa J. M. , Dorf G. 
Published: December 2008

Abstract.
A Caucasian female, aged 28 years, presenting with obesity and investigated for primary amenorrhoea, was found to have hydrocephalus due to a stenosis of the foramen of Magendie.
Endocrine investigations showed an isolated gonadotrophin deficiency. Complete recovery was obtained by a ventricular-cardiac shunt, which led to the return of menses, a normal pregnancy, and then a return to normal weight.
Thyrotrophin and prolactin responses to thyrotrophin-releasing hormone in patients with streak gonad syndrome
Authors: Bösze P. , Kóvacs Zs. , Egyed J. , László J. , Szilágyi G. 
Published: December 2008

Abstract.
Plasma TSH and Prl responses to iv TRH (200 μg) were studied in 21 euthyroid patients with streak gonad syndrome which is characterised by high levels of FSH and LH and low level of oestrogen and in 9 healthy women. The syndrome is associated with a variety of chromosome complements. Basal TSH and Prl responses to TRH were normal in patients with streak gonads irrespective of their chromosomal complements. Peak levels of both the TSH and Prl occurred at 15–30 min following TRH. The data might suggest that in hypergonadotrophic oestrogen deficiency neither the TSH nor the Prl response to TRH are attenuated. It does not seem that the associated chromosome anomalies alter the TSH and Prl responses to TRH in euthyroid affected patients.
Comparison of the LH secretion patterns in the male rat following infusion of LRH and of the LRH-analogue buserelin®. Influence of castration and oestradiol benzoate on the efficiency of LH release
Authors: Schuiling G. A. , Pols-Valkhof N. , Koiter T. R. 
Published: December 2008

Abstract.
The LH releasing activities of LRH and the LRH-analogue buserelin® (HOE 766; (D-Ser (But)6-LRH(1–9)nona peptide-ethylamide) were compared in intact and short- and long-term castrated male rats, pre-treated (either 1 or 3 days) with oestradiol benzoate (EB) or oil.
LRH and buserelin were infused iv at the constant rate of 104 ng/h for 21 h. Blood samples were taken from an intracarotid cannula. LH responses were judged on the basis of the mean maximal height of the LH concentration (MH; ng LH/ml plasma) and a parameter of total LH release, i.e. the area under the curve of LH concentrations plotted against time ('area under the curve', AUC; expressed in 'area units'). The release efficiency of LRH and buserelin, E (see for a definition: Materials and Methods), which informs on the total quantity of LH released in relation to pituitary LH content, was calculated by dividing the AUC × 100 by the pituitary LH content at the beginning of stimulation.
Maximal plasma LH concentrations were observed between t= 1.5 and t=3 h after LRH and between t= 1.5 and t=9 after buserelin treatment. Both with LRH and buserelin the rise of LH secretion was greater the longer the animals were castrated and/or pre-treated with EB. The buserelin-induced LH response (with the exception of the responses induced in the EB-pre-treated, 4-weeks castrated rat) were about 2–2.5 times higher (MH) and larger (AUC) than the corresponding LRH-induced responses. The buserelin/LRH potency ratio, therefore, is about 2–2.5.
EB-pre-treatment did not change the pituitary LH content. It therefore enhanced the efficiency of release of LH of both LRH and buserelin. Castration, on the other hand, caused an increase of the pituitary LH content: after 4 weeks it was raised by a factor 4. Since, however, the LH responses induced by LRH and buserelin were proportionally higher and larger, castration did not significantly change the efficiency of LH release.
The results indicate that the efficiency of LH release can be changed by changes in the endocrine environment in the experimental animals, whilst for the magnitude of LH responses the pituitary LH content is also important. It is therefore suggested that the responsiveness of the pituitary gland to LRH (and agonistic analogues) is determined by (1) the state of the LH secretion mechanism and (2) the pituitary LH content.