bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of metyrapone infusion on corticotropin-releasing factor and arginine vasopressin secretion into the hypophysial portal blood of conscious, unrestrained rams
Authors: Conte-Devolx B , Guillaume V , Boudouresque F , Graziani N , Magnan E , Grino M , Emperaire N , Nahoul K , Cataldi M , Oliver C
Published: June 2009

The effects of rapid changes of circulating cortisol levels on ACTH secretion and on corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) concentrations into hypophysial portal blood were studied in six adult rams. Pharmacological adrenalectomy was obtained by 3 h metyrapone infusion (100 mg·kg−1·h−1). Blockade of cortisol synthesis induced a tenfold increase of plasma ACTH levels accompanied by a moderate increase of CRF secretion (150% vs preinjection levels) and a large increment of AVP secretion (535% vs preinjection levels). ACTH levels remained high during the 3 h following the end of metyrapone infusion. During the same period, CRF secretion was still elevated (231% vs preinjection levels), while AVP secretion was further stimulated (2,151% vs preinjection levels). Subsequent hydrocortisone infusion (66 μg·kg−1·h−1) for 2 h induced a rapid decrease of both ACTH and AVP secretion, while CRF levels in hypophysial portal blood still remained elevated. These data suggest that changes in ACTH secretion induced by acute modifications of the negative glucocorticoid feedback are, in addition to the well documented direct effect of cortisol on the corticotropes, mainly mediated by variations of hypothalamic AVP secretion.
Evidence for specific binding and stimulatory effects of recombinant human erythropoietin on isolated adult rat Leydig cells
Authors: Mioni Roberto , Gottardello Francesco , Bordon Paola , Montini Gianni , Foresta Carlo
Published: June 2009

The presence of specific binding of recombinant human erythropoietin and its effect on testosterone production were evaluated in isolated intact adult rat Leydig cells. Maximal specific binding was observed after 135 min incubation at 34°C. Scatchard analysis of the binding data revealed two distinct classes of binding sites for [125I]-recombinant human erythropoietin with dissociation constant of(Kd1) 1.9× 10−10mol/l and (Kd2) 1.37× 10−8 mol/l respectively and binding capacity of (Bmax1) 12.3fmol/l 106 cells and (Bmax2) 42.8 fmol/106 cells, respectively. GnRH, hCG, IGF-I and EGF did not induce any modification of recombinant human erythropoietin-specific binding. Recombinant human erythropoietin added to isolated adult rat Leydig cells exerted a stimulatory effect on testosterone production reaching its maximal effect at the dose of 10−10 mol/l (testosterone production from 14.9±1.7 to 45.1±6.2 pmol/106 cells/3 h). Addition of anti-recombinant human erythropoietin serum completely blocked the recombinant human erythropoietin-stimulated testosterone production. These results show that purified adult rat Leydig cells possess recombinant human erythropoietin specific binding, and suggest that this glycoprotein directly influences rat Leydig steroidogenesis.
Fibronectin production by chicken granulosa cells in vitro: effect of follicular development
Authors: Asem Elikplimi K , Carnegie Jacqueline A , Tsang Benjamin K
Published: June 2009

In vitro studies were conducted to investigate the role of chicken ovarian granulosa cells in the production of fibronectin, a component of the basal lamina of ovarian follicles. Collagenase dispersed granulosa cells obtained from the first (F1; about 35 mm in diameter) and third (F3; 15–20 mm in diameter) largest preovulatory follicles, as well as from a pool of small yellow follicles (SF; 6–10 mm in diameter), were incubated in serum-free medium-199 for 24 to 96 h in the absence and presence of luteinizing hormone (LH) or forskolin. Fibronectin secreted in the medium was quantitated by enzyme linked immunosorbent assay. Basal fibronectin production (which increased with the duration of incubation) was significantly greater (p<0.001) in granulosa cells derived from mature follicle (F1) than in F3 or SF cells. Both LH and forskolin stimulated fibronectin production in SF and F3 cells in a dose-dependent manner; however, they were without effect in F1 cells. The magnitude of increase in fibronectin production elicited by LH or forskolin was greater in SF cells than in F3 cells. The cytoplasm of cultured granulosa cells taken at all stages of follicular development stained positively for fibronectin. These findings indicate that chicken granulosa cells produce fibronectin. This ability is acquired early in follicular development and the stimulatory effect of the gonadotropin (LH) diminished as the follicle approached ovulation.
Bioregulatory role of the kallikrein-kinin system in the normal pituitary gland and its tumours
Authors: Jones TH , Figueroa CD , Bhoola KD
Published: June 2009

Tissue kallikrein, a serine protease, is present in the prolactin-secreting cells of the normal anterior pituitary gland and pituitary adenomas. It is mainly located in the Golgi apparatus, but is also present in secretory granules. There is a distinct sexual dimorphism, with amount of tissue kallikrein being greater in anterior pituitary tissue from female rats. The intracellular levels of tissue kallikrein are increased by estradiol and in pituitary tumours, and decreased by ovariectomy, dopamine and its agonists. There is preliminary in vitro evidence that tissue kallikrein may be involved in the intracellular processing of the prolactin molecule before secretion. Tissue kallikrein synthesizes kinins which are present in the anterior pituitary and are capable of stimulating prolactin and growth hormone secretion by activating the phosphoinositide second messenger system. Prolactin physiology is uniquely linked to the kallikrein-kinin system in the normal pituitary and its tumours. Tissue kallikrein may have an important role in the pathophysiology of prolactin-secreting pituitary adenomas.
Growth hormone binding protein in patients with renal failure
Authors: Maheshwari Hiralal G , Rifkin Ian , Butler Joan , Norman Michael
Published: June 2009

To investigate changes in the growth hormone binding protein (GH-BP) in renal disease, gel chromatography was used to separate free and bound hormone after incubation with 125I-GH, the results being expressed as a percentage of radioactive GH eluting in a high molecular weight (70–80 kD) peak. In 26 normal individuals, binding was 39.3±8.0%, while in 11 patients with renal disease who were off dialysis binding was reduced to 16.8±5.6%. Similarly, in 9 patients undergoing hemodialysis binding was reduced to 24.6±6.8%, in 8 patients undergoing chronic ambulatory peritoneal dialysis binding was reduced to 25.7±7.6%, and in 9 patients within three months of a renal transplant binding was reduced to 25.1±8.6%. Scatchard analysis showed that these changes were not a result of decreased affinity of GH-BP for GH, and receptor binding studies showed that uremic serum was not inhibiting binding. The decreased concentration of GH-BP may indicate decreased expression of the GH receptor in target tissues, and hence diminished responsiveness to GH in renal failure.
Cholinergic modulation of GH secretion in acromegalic patients before and after pituitary surgery
Authors: Fiszlejder Leon , Penacini Olga , Ratz Susana , Oneto Adriana , Storani Maria , Rizzo Leonardo , Guitelman Abraham
Published: June 2009

Cholinergic neurotransmission exerts a physiological control on GH secretion. Pirenzepine (Pz), an antagonist of muscarinic receptors, by enhancing hypothalamic somatostatin release, inhibits stimulated GH secretion in normal subjects but not in acromegalic patients. To address the hypothesis that a feedback effect of GH hypersecretion can be involved in this condition, GH responses to GHRH 1–29, 1 μg/kg iv, with and without administration of Pz, 40mg iv before tests, were investigated in eight acromegalic patients, before and 20–30 days after transsphenoidal adenomectomy. Pz diminished (p<0.001) the incremental area under the curve (AUC) of GH responses to GHRH in seven normal controls. In contrast, GHRH responsiveness in untreated acromegalic patients was not affected by Pz. Postoperative basal GH levels decreased by 62.4±14.9% (p<0.01). Pz inhibited GH responses to GHRH (p<0.01). Furthermore, a direct relationship (r = 0.73, p<0.01) between basal concentrations and the AUC of GH responses following Pz plus GHRH-test was found. The finding that muscarinic receptor activity recovered after the reduction of serum GH basal levels by pituitary surgery lends support to the proposed pathophysiological role of GH excess as a possible determinant factor in cholinergicsomatostatinergic dysfunction in acromegaly.
Effect of insulin-like growth factor I on the thyroid axis in patients with Laron-type dwarfism and healthy subjects
Authors: Klinger Beatrice , Ionesco Anna , Anin Sarah , Laron Zvi
Published: June 2009

We have evaluated the effect of exogenous administration of IGF-I on the thyroid axis in four separate studies: (1) iv bolus injection; (2) single sc injection; (3) seven days' sc treatment, and (4) four months' treatment. Thirteen patients with Laron-type dwarfism (LTD) participated in the investigations. In studies 1 and 2,10 healthy subjects were also included. Before and during long-term treatment (study 4) six LTD patients underwent a TRH test. IGF-I was administered in a dose of 75 μg·kg−1 iv or 120– 150 μg· kg− 1 sc. Single injections of IGF-I caused significant decreases of serum TSH in LTD patients (iv: 1.7±0.2 to 1.1±0.1 mU/l; sc: from 2.1±0.4 to 1.1±0.2; p<0.0005). In controls the decrease was for iv from 1.2±0.2 to 0.8±0.2 mU/l (p<0.02) and for sc from 2.0±0.5 to 0.8±0.2 mU/l (p<0.05). Long-term administration of IGF-I induces a transitory decrease of both serum TSH and fT4, followed by a spontaneous rise to pretreatment or even higher values. No changes in T3 were observed. TSH stimulation by TRH was significantly augmented after four months of IGF-I treatment (p<0.005). The effects of IGF-I can be explained by an early stimulation of somatostatin release causing a decrease in TSH and followed by the development of compensatory mechanisms. All changes were within the normal ranges, not causing abnormal thyroid function. As the clinical use of recombinant IGF-I extends for longer periods than those described, it is recommended that thyroid function is followed.
Evaluation of acromegaly by measurement of 24-hourly urinary growth hormone excretion
Authors: Pholséna Maryse , Le Bouc Yves , Rousseau Elisabeth , Christol Rémy , Birman Pascal , Périn Laurence , Girard François
Published: June 2009

Twenty-four hourly urinary growth hormone excretion (24-h uGH) has been quantified using a combination of ultrafiltration and conventional immunoradiometric assay. Twenty-four hourly uGH was measured in 20 normal adults and in 42 patients with acromegaly (9 untreated, 28 treated but with above-normal IGF-I levels, and 5 treated and cured). The means and ranges were as follows: 3.7 (1–9) ng/24 h for normals and 160(40–540), 66(2–380) and 5.2 (4–8) ng/24 h for the three groups of acromegalic patients, respectively. Ten patients with pituitary adenomas without acromegaly had 24-h uGH within the normal range. Twenty-four hourly uGH therefore gives a clear differentiation between controls and untreated patients. Log-transformed values for subjects with acromegaly showed significant correlations between 24-h uGH and levels of IGF-I (r=0.63, p<0.01), fasting plasma GH (r=0.92, p<0.001) and plasma GH after glucose loading (r=0.85, p<0.001). Twenty-four hourly uGH was also determined in three acromegalic patients before and during SMS 201–995 therapy. Twenty-four hourly uGH reflected the corresponding changes in mean levels for hourly sampling over 12 h of plasma GH and IGF-I and in clinical signs after 3–6 months of therapy. The results of this study indicate that 24-h uGH is an accurate indicator of GH secretion in acromegalic patients and could therefore be used both in diagnosis and in monitoring the progress of therapy in these patients.
Effects of adrenal function tests on the levels of endogenous digitalis-like substances and some pituitary hormones
Authors: Vinge Ellen , Erfurth Eva Marie T , Lundin Stefan
Published: June 2009

In order to study the influence of the hypothalamic-pituitary-adrenal axis on the levels of endogenous digitalis-like substances (EDLS) in plasma and urine, eight healthy subjects (25–40 years old) were given dexamethasone 1 mg orally and tetracosactide (an ACTH analog) 0.25 mg iv, on separate occasions. The circulating levels of EDLS, TSH, PRL and AVP following administration of either test drug, and under control conditions, were measured by a RIA for digoxin and specific RIAs for each hormone. Plasma cortisol was measured by liquid chromatography. The area under the curve (AUC) of hormone levels between 08.00 and 09.30 was used for data comparisons. Urine was collected before and after each test dose, and analysed for cortisol levels by gas chromatography/mass spectrometry, and for digitalis-like activity both by RIA and by a bioassay measuring 86Rb-uptake into red blood cells. Dexamethasone suppressed the AUC of plasma and urine levels of cortisol (p=0.0001 and p<0.01, respectively) and immunoreactive EDLS (p=0.0007 and p<0.01), as well as serum levels of TSH (p=0.0002) and PRL (p=0.001), but did not alter AVP levels. The biological digitalis-like activity in the urine measured by the 86Rb-uptake assay was decreased, but not to a statistically significant degree. ACTH increased the levels of cortisol in plasma (p=0.0001) and urine (p<0.01) and the immunoreactive EDLS in plasma (p = 0.03), but not in urine. There were no effects of ACTH on TSH, PRL or AVP. There are alternative explanations for the discrepancy between the effects on EDLS levels in plasma and urine: methodological difficulties in quantitating EDLS, the doses of dexamethasone and ACTH used for the adrenal function tests, and that other hypothalamic or pituitary factors than ACTH may contribute to a significant degree in the regulation of EDLS levels. Taken together, the results of the present study support the hypothesis that EDLS is of adrenal origin, rather than hypothalamic or pituitary.
Circulating levels and bone contents of bone γ-carboxyglutamic acid-containing protein in rat models of non-insulin-dependent diabetes mellitus
Authors: Takeshita Noritaka , Ishida Hitoshi , Yamamoto Taizo , Koh Gyohan , Kurose Takeshi , Tsuji Kazuo , Okamoto Yoshimasa , Ikeda Hitoshi , Seino Yutaka
Published: June 2009

In order to investigate the pathophysiology of the diabetic osteopenia observed in non-insulin-dependent diabetes mellitus, the circulating levels and the bone contents of bone γ-carboxyglutamic acid-containing protein (osteocalcin) were determined in rat models of non-insulin-dependent diabetes mellitus, neonatally streptozotocin-induced rats and in genetic Wistar fatty rats. In Wistar fatty rats the plasma level of osteocalcin was 8.1±0.8 nmol/l, significantly lower than the value of 1 7.3±0.9 nmol/l in their lean littermates (p<0.001). Bone length, bone strength, and weight of powdered bone in Wistar fatty rats were significantly decreased compared to control rats (p<0.001, p<0.02 and p<0.001, respectively). Bone content of osteocalcin per femur in Wistar fatty rats was also significantly decreased compared to controls (p<0.001). In addition, plasma osteocalcin in neonatally streptozotocin-induced diabetic rats was 2.9±0.3 nmol/l, which was also significantly decreased compared to the value of 5.6±0.5 nmol/l in their controls (p<0.001). Since it has been established that the plasma level of osteocalcin is well related to bone formation and turnover, the low plasma values in these animal models suggest that bone formation and turnover are decreased in non-insulin-dependent diabetes mellitus. Low bone formation and turnover are, therefore, postulated to be one of the pathophysiological characteristics of the skeletal tissue in non-insulin-dependent diabetes mellitus, and to be at least in part responsible for the occurrence of this complication.
Biological activity of partially purified low molecular weight luteinizing hormone binding inhibitor in porcine follicular fluids
Authors: Kokawa Nobuyoshi , Yamoto Mareo , Furukawa Kenichi , Nakano Ryosuke
Published: June 2009

We performed partial purification of low molecular weight luteinizing hormone binding inhibitor from porcine follicular fluids and examined its biological activities. Following ultrafiltration, gel filtration and anion exchange of the pooled porcine follicular fluids, low molecular weight fractions (500–10,000 MW) inhibited [125I]hLH binding to porcine granulosa cells in a dose-dependent manner. The binding inhibition kinetics study revealed that the luteinizing hormone binding inhibitor may indicate a non-competitive inhibition with [125I]hLH binding. In vitro bioassay using adult mouse testicular interstitial cells revealed that the partially purified luteinizing hormone binding inhibitor reduced ovine LH-stimulated testosterone and cAMP production in a dose-dependent manner, whereas the luteinizing hormone binding inhibitor did not affect basal production of testosterone and cAMP. The inhibitory activity was heat stable and did not disappear with activated charcoal adsorption. The results of the present study suggest that the luteinizing hormone binding inhibitor may play an important role as an ovarian non-steroidal regulator modulating the receptor binding of LH and LH-mediated steroidogenesis.
Adrenergic regulation of α-MSH secretion in man: evidence for a stimulatory role of β-receptors
Authors: Limone Paolo , D'Alessandro Valerio , Rainero Innocenzo , Ambrogio Caterina , Pinessi Lorenzo , De Gennaro Tiziana , Molinatti Gian Michele
Published: June 2009

In several animal species the catecholamines stimulate the release of α-MSH from the melanotrope cells of the pituitary neurointermediate lobe through β-receptors. The human hypophysis does not include a well-defined intermediate lobe and the methods for measuring α-MSH are often poorly sensitive. Neuroregulation of this hormone in man has thus received little attention. To see whether the adrenergic system is involved in the control of α-MSH secretion and whether the latter is independent of that of other peptides derived from proopiomelanocortin, such as ACTH, we studied the effects on plasma α-MSH-like immunoreactivity (α-MSH-LI). ACTH, and cortisol of some adrenergic drugs active on the β-receptors. Six normal volunteers underwent the infusion of the following drugs: isoproterenol (0.03 μg·kg−1·min−1 for 60 min), propranolol (1 mg·min−1 for 5 min followed by 0.1 mg·min−1 for 115 min), propranolol + isoproterenol (infused between 30 and 90 min of propranolol infusion), placebo (saline solution). Isoproterenol increased α-MSH-LI at 1 5 min (p<0.001). Propranolol induced a fall of α-MSH-LI between 30 and 60 min (p<0.001), followed by a return to preinfusion concentrations beginning at 75 min, and completely prevented the stimulatory effect of isoproterenol. Plasma ACTH and serum cortisol were always unaffected. These results indicate that in man the adrenergic system stimulates α-MSH-LI release through β-receptors, and that α-MSH-LI secretion is dissociated from that of ACTH and cortisol. This in turn suggests that separate neuroregulatory mechanisms exist for the melanotrope and corticotrope cells.
Evidence for the presence of fatty acid binding protein in avian granulosa cells
Authors: Nemecz Gyorgy , Asem Elikplimi K
Published: June 2009

The existence of fatty acid binding protein in chicken ovarian granulosa cells was investigated using a fluorescent assay based on the ability of cis-parinaric acid to fluoresce as a result of its interaction with proteins. Cytosolic fractions were prepared from granulosa cells obtained from the first (F1), second (F2), and third (F3) largest preovulatory follicles, as well as from a pool of small yellow follicles of the chicken ovary, and each fraction was incubated with different concentrations of cis-parinaric acid. Total fluorescence increased (but fluorescence per milligram protein decreased) as the quantity of cytosolic protein from all follicle types was increased. Cis-parinaric acid fluorescence (which was also dosedependent) was observed within 2 sec and increased with time reaching a plateau at about 10 sec. It was greater (p < 0.001) in the cytosolic fraction from F3 and small yellow follicle groups compared with F2 and F1 groups. Arachidonic, palmitic, oleic and stearic acids attenuated the fluorescence in dose-dependent fashion in cytosol from all follicle types presumably by displacing cis-parinaric acid from protein. Whereas arachidonic acid was most effective in suppressing fluorescence in fractions from F1 follicles, arachidonic acid lost part of its suppressive potency in fractions from F3 or small yellow follicles, and in these fractions palmitic acid was the most potent suppressor of fluorescence. These results indicate the existence of fatty acid binding protein-like activity in chicken granulosa cells and demonstrate that its concentration is greatest in the immature follicles. This protein could play an important role in the transport of fatty acids within granulosa cells.
Interaction between the α2-adrenergic system and nursing in the regulation of growth hormone secretion in the neonatal rat
Authors: Kacsóh Bálint , Opp (Meyers) Judith S , Crowley William R , Grosvenor Clark E
Published: June 2009

Separation of neonatal rats from their mothers decreases, while a subsequent period of suckling (nursing) increases, serum growth hormone (GH) levels in neonatal rats. Milk-borne (humoral) factors and neural factors inherent in mother-offspring interaction have been implicated in these phenomena. Conflicting reports have demonstrated the α2-adrenergic agonist clonidine to increase and to decrease serum GH levels in 10-day-old rats. The present experiments were aimed at testing whether an interaction between the α2-adrenergic system and the nursing-induced changes in GH secretion could account for the discrepancy. Rat pups were treated with clonidine (150 μg/kg) or the α2-adrenergic antagonist yohimbine (10 mg/kg), and the drug treatment was combined with separation of the mothers and nursing. Yohimbine did not affect serum GH levels in separated two-day-old pups (i.e. basal levels of the hormone), but prevented the nursing-induced increase in serum GH concentration. In two-day-old pups, clonidine had no effect on basal GH levels but, like yohimbine, prevented the increase in serum GH normally associated with nursing. Both yohimbine and clonidine prevented active sucking behavior, i.e. the pups did not search for and/or attach to the nipples of their mothers. Moreover, the pups treated with yohimbine and clonidine were cooler to the touch than the littermate controls. In eight-day-old pups, yohimbine prevented the nursing-induced increase in serum GH and decreased GH levels below the saline-injected, separated control. As in two-day-old pups, clonidine prevented the suckling-induced release of GH and failed to induce GH-release above that of saline-injected, separated pups. By day 10 postpartum. clonidine became capable of stimulating GH release, but only in separated male pups. The effects of CLO and nursing in male pups were not additive: either treatment alone was as effective as the combined treatment. In female rats CLO prevented the increase in serum GH levels in response to nursing. It is concluded that (1) the α2-adrenergic agents yohimbine and clonidine inhibit nursing-induced GH secretion in an indirect (perhaps hypothermia-related) manner not involving the well-established α2-adrenergic-GH releasing hormone pathway; (2) the α2-adrenergic system becomes fully functional in terms of stimulation of GH secretion between days 8 and 10; (3) the GH-releasing effects of the α2-adrenergic system are sexually dimorphic in 10-day-old rats.
Subclinical hypothyroidism and hyperlipoproteinaemia: indiscriminate L-thyroxine treatment not justified
Authors: Bogner U , Arntz H-R , Peters H , Schleusener H
Published: June 2009

It is still under discussion whether subclinical hypothyroidism is a biochemical syndrome or a disease associated with an increased risk for development of vascular diseases due to lipid elevation. Therefore, we investigated lipid values in 40 patients with subclinical hypothyroidism, which is defined in terms of normal (N =26) or slightly increased (N= 14) basal TSH values and/or an exaggerated TSH response (N=34) to TRH (>25 mU/l). Patients with increased lipid values were treated with L-thyroxine and reanalysed three months later. Mean levels of total cholesterol, LDL- and HDL-cholesterol and triglycerides in patients with subclinical hypothyroidism were comparable with those in normal subjects. Individual analysis, however, revealed hyperlipoproteinaemia (HL) in 22.5% of the patients investigated (HL type Ila in seven, type IV in two patients). Thyroid function was the same in affected patients as in those with normal lipid values, whereas higher age was significantly more often associated with this syndrome (p <0.01). Treatment with L-thyroxine resulted in a significant decrease in total and LDL-cholesterol (p<0.05), although a normalization of their lipid values could be obtained only in half of the patients. None of the subjects with hyperlipoproteinaemia had a history or clinical signs of actual vascular disease. Although the incidence of hyperlipoproteinaemia in our study group of patients with mild subclinical hypothyroidism (22.5%) is comparable to that of the normal population (21.5%), it is more severe in the former group (LDL-cholesterol in patients 5.26±0.58 vs 4.8±0.56 mmol/l in controls: p<0.05). Formally, approximately half of the patients with this syndrome benefit from L-thyroxine treatment with a normalization of their total and LDL-cholesterol. In the remaining patients with hyperlipoproteinaemia, elevated lipid levels do not seem to be associated with borderline thyroid dysfunction. We conclude that indiscriminate L-thyroxine treatment is not justified in subclinical hypothyroidism.
Human early placental trophoblasts produce an epidermal growth factor-like substance in synergy with thyroid hormone
Authors: Matsuo Hiroya , Maruo Takeshi , Murata Kazuo , Mochizuki Matsuto
Published: June 2009

Previous studies have shown that human trophoblast is the site of epidermal growth factor (EGF) localization, reception and action and that thyroid hormone exerts similar effects on trophoblasts endocrine function as observed with EGF. Thus, the present study was designed to examine local production of an EGF-like substance in synergy with thyroid hormone by early placenta. Explants of normal early (7-8 weeks) placentas were cultured in a serum-free condition in the presence or absence of L-triiodothyronine (T3), with or without cycloheximide for 4 days. The conditioned media were dialyzed, lyophilized, acidified and chromatographed over a Sephadex G-75 column equilibrated with 1 mol/l acetic acid. EGF was measured by a specific RIA for human EGF. Fractionation of the serum-free conditioned media resulted in the elution of immunoreactive EGF with an apparent molecular weight of 9.000 which is larger than [125I]human EGF. The addition of T3 (10−8 mol/l) resulted in increased secretion of immunoreactive EGF by placental explants. By contrast, the addition of cycloheximide (5× 10−5 mol/l) dramatically reduced the secretion of immunoreactive EGF. The similarity of the immunoreactive EGF material to authentic human EGF was supported by parallel displacement in human EGF-RIA. These results suggest that human early placental trophoblast is capable of producing an EGF-like substance and that thyroid hormone enhances the local production of the EGF-like substance. This suggests that an autocrine/paracrine control system, wherein EGF serves as the signal in regulating placental growth and function in synergy with thyroid hormone, exists in human early placenta.
Multihormonal response to CRH in a patient with Cushing syndrome and a pituitary adenoma producing ACTH and GH
Authors: Bugalho Maria João GM , Nunes JF Moura , Sobrinho LG , Medina E , Campos JA Martins , da Silva C Gomes , Clode Ana L
Published: June 2009

Preoperative bilateral and simultaneous catheterization of the inferior petrosal sinuses was performed in a patient with Cushing's syndrome. This procedure revealed parallel intersinus gradients for ACTH, PRL, GH and a response of all these hormones to CRH. The patient had transphenoidal surgery and a soft white-yellowish mass occupying the whole sella conditioned a total hypophysectomy. Morphologic studies and immunostaining techniques revealed a rare mixed pituitary adenoma of ACTH and GH containing cells and failed to demonstrate PRL immunoreactivity in the tumor cells. These results are of clinical and speculative interest. Whether GH and PRL secretion in response to CRH stems from the tumor or reflect hormone release by non-tumor cells via a paracrine effect remains to be defined.
The pattern of gonadotropin and estradiol secretion in exaggerated thelarche
Authors: Garibaldi Luigi R , Aceto Thomas , Weber Colleen
Published: June 2009

Purpose:

To assess the dynamics of the pituitary-ovarian axis in exaggerated thelarche, defined as premature thelarche associated with signs of systemic estrogen effects (advanced bone age and/or growth acceleration) without progression to complete puberty. Subjects and methods: Seven girls (age <2.5 years) with exaggerated thelarche, 6 girls with inactive pituitary-ovarian axis (premature adrenarche) and 21 girls with activated axis (central precocious puberty) had serum FSH, LH and E2 measured serially before and 1 to 24 h after gonadotropin-releasing hormone agonist (GnRHa) administration (leuprolide, 20 μg/kg sc), used as a test of combined pituitary-ovarian stimulation. Results: Although girls in the exaggerated thelarche and adrenarche group had similar [mean (SEM)] baseline FSH [3.2 (0.9) vs 1.4 (0.3) IU/I], LH [0.36(0.1) vs 0.27 (0.02) IU/I] and E2 [20 (1.2) vs 21 (2) pmol/l] concentrations, and similar peak post-GnRHa LH concentrations [5.5 (1.1) vs 2.4 (0.5) IU/I], girls with exaggerated thelarche achieved higher peak FSH [41(9) vs 14 (3) IU/I, p< 0.01] and E2 [243 (40) vs 37 (6) pmol/l, p<0.001] concentrations after GnRHa. In comparison to patients with exaggerated thelarche, girls with precocious puberty had higher (p<0.01-0.001) baseline LH [3.6 (0.8) IU/I], baseline E2 [69 (11) pmol/l], GnRHa-stimulated peak LH [68 (1 7) IU/I] and peak E2 [648 (58) pmol/l] concentrations, but similar FSH parameters. Conclusions: Girls with exaggerated thelarche exhibit substantial E2 secretory potential that can be demonstrated by GnRHa stimulation, is predominantly FSH-driven, and probably accounts for the manifestations of estrogen effect seen in these girls.
Non-responsiveness of serum gonadotropins and testosterone to pulsatile GnRH in hemochromatosis suggesting a pituitary defect
Authors: Duranteau Lise , Chanson Philippe , Blumberg-Tick Joelle , Thomas Guy , Brailly Sylvie , Lubetzki Jean , Schaison Gilbert , Bouchard Philippe
Published: June 2009

We investigated the potential pituitary origin of gonadal insufficiency in hemochromatosis. Gonadotropin secretion was studied in seven patients with hemochromatosis and hypogonadism, before and after chronic pulsatile GnRH therapy. Pulsatile LH secretion was studied before (sampling every 10 min for 6 h) and after 15-30 days of chronic pulsatile GnRH therapy (10-12 μg per pulse). Prior to GnRH therapy, all the patients had low serum testosterone, FSH and LH levels. LH secretion was non-pulsatile in four patients, while a single pulse was detected in the remaining three. Chronic pulsatile GnRH administration did not increase serum testosterone levels; similarly, serum LH levels remained low: neither pulse frequency nor pulse amplitude was modified. We conclude that hypogonadism in hemochromatosis is due to pituitary lesions.
Individual and combined effects of intact PTH, amino-terminal, and a series of truncated carboxyl-terminal PTH fragments on alkaline phosphatase activity in dexamethasone-treated rat osteoblastic osteosarcoma cells, ROS 17/2.8
Authors: Nakamoto Chizu , Baba Hisamitsu , Fukase Masaaki , Nakajima Kiichiro , Kimura Terutoshi , Sakakibara Shumpei , Fujita Takuo , Chihara Kazuo
Published: June 2009

The individual and combined effects of intact PTH, amino-terminal, and a series of truncated carboxyl-terminal PTH fragments on alkaline phosphatase activity were examined in dexamethasone-treated rat osteoblastic osteosarcoma cells ROS 17/2.8. Dexamethasone-induced alkaline phosphatase activity was inhibited not only by hPTH(1–84) and amino-terminal PTH fragment hPTH(1–34), but also by carboxyl-terminal PTH fragment hPTH(69–84) in a dose-related fashion. At 10−7 mol/1, hPTH(1–84) completely abolished dexamethasone-induced alkaline phosphatase activity, while hPTH(1–34) and hPTH(69–84) reduced alkaline phosphatase activity to 0.16±0.02 and 0.80±0.03 fold, respectively, of the control value obtained in the absence of PTH peptides. The combination of hPTH(1–34) and hPTH(69—84) resulted in reduction of alkaline phosphatase activity to the level obtained by hPTH(1-84). The shorter carboxyl-terminal PTH fragment hPTH(71–84) did not affect alkaline phosphatase activity or modulate the action of hPTH(1–34). The longer carboxyl-terminal PTH fragment hPTH(53-84) stimulated alkaline phosphatase activity up to 1.23±0.03 fold and partially blunted the inhibitory effect of hPTH(1–34) on alkaline phosphatase activity. These findings suggest that carboxyl-terminal PTH fragments could exert diverse effects on the target cells, depending on the length of deletion of amino-terminal amino acids of PTH molecule, and interact with amino-terminal PTH fragment. The two amino-terminal amino acids of hPTH(69–84) and the 53–68 portion of hPTH(53–84) might be responsible for the respective inhibitory and stimulatory effects of the peptides on alkaline phosphatase activity.
Unpredictable hypersecretion of cortisol in Cushing's disease: detection by daily salivary cortisol measurements
Authors: Hermus Ad R , Pieters Gerlach F , Borm George F , Verhofstad Albert A , Smals Anthony G , Benraad Theo J , Kloppenborg Peter W
Published: June 2009

A 70-year-old man with mild signs and symptoms of Cushing's syndrome due to an ACTH-secreting pituitary adenoma is described. He had a completely unpredictable pattern of urinary excretion of cortisol; 24 h urine for determination of cortisol excretion was collected daily at home on 725 consecutive days. During this period there were eight episodes in which urinary cortisol excretion exceeded the upper limit of normal. Within these episodes the pattern of cortisol secretion was extremely unpredictable, with cortisol excretion ranging from normal to highly elevated. Using a Cluster Analysis Program 61 pulses of cortisol excretion were detected within the eight periods of cortisol hypersecretion. The interval between two pulses varied from 2 to 12 days. Between the periods of cortisol hypersecretion, urinary cortisol excretion was completely normal, lasting from 4 to 102 days. There was no difference in the clinical expression of Cushing's syndrome between the periods of elevated and normal urinary cortisol excretion. During the last 439 days of the observation, cortisol was also measured in saliva collected at home at 09.00 after an overnight fast. The salivary cortisol pattern closely resembled that of urinary cortisol excretion and there was a significant correlation between salivary cortisol levels and 24 h urinary cortisol excretion in the 24 h after (r=0.42, p<0.0001, Spearman) and before saliva collection (r = 0.44, p<0.0001). On 71% of occasions cortisol peaks in saliva, as detected by the Cluster Analysis Program, coincided with urinary cortisol peaks. We conclude that daily measurement of cortisol in saliva, collected at home, is a convenient and reliable method for detecting intermittent hypercortisolism in patients with Cushing's syndrome.
Effect of the antioxidant TK 12627 (Irganox) on monodeiodination and on the levels of messenger ribonucleic acid of 5′-deiodinase type I and spot 14
Authors: Liang H , Morin O , Burger AG
Published: June 2009

Until now, most potent inhibitors of monodeiodination are iodinated, propylthiouracil being an exception. We report here studies on a new non-iodinated substance, triethylene glycol bis-3-(3-tertbutyl-4-hydroxy-5-methyl-phenyl) propionate (TK 12627 or Irganox), which is used as a very efficient antioxidant in the chemistry of plastics. The studies were performed with 23 hypothyroid rats that received Irganox in their daily food (8 mg·day−1·(100 g body wt)−1) for 3 weeks. Thyroxine (T4) metabolism was studied by implanting minipumps delivering 2.3 nmol T4·dayℒ1·(100 g body wt)ℒ1 for 1 week. On day 1 before sacrifice, another minipump containing [125I]-3,5,3′-triiodothyronine (T3, 2.6 μCi/day) and [131I]-3,3′,5′-triiodothyronine (rT3, 2.1 μCi/day) was implanted. The results showed that with Irganox treatment serum T4 concentrations were higher (p<0.05). Serum T3 concentrations markedly decreased (1.07±0.07 vs 0.65±0.04 nmol/l), accompanied by a decrease of free T3 concentrations (p<0.001). Serum rT3 concentrations increased by 50% (p<0.001). Serum thyrotropin levels were mostly unmeasurable. The plasma clearance rate decreased slightly for T4 (19%, p<0.05) and remarkably for rT3 (46.7%, p<0.001). The conversion rate of T4 to rT3 did not change. Deiodinase type I (5′D-I) activity decreased in both liver and kidney tissues by 54% and 52%, respectively, and correlated with T3 (r2 = 0.79 and 0.65, respectively). Brain deiodinase type III (5D-III) was unchanged and type II (5′D-II) was unmeasurable. The relative abundance of 5′D-I messenger ribonucleic acid (mRNA) levels decreased by 40% in liver and 42% in kidney and it correlated with serum T3 levels also (r2 = 0.71 and 0.72, respectively). The amount of hepatic spot 14 mRNA also decreased by 41% (p<0.05); however, the abundance of hepatic beta-actin mRNA was not affected by the treatment. In an additional experiment. Irganox-treated rats received 2 nmol T3 ·day−1·(100 g body wt)−1; this treatment prevented the changes in mRNA levels of 5′D-I and spot 14 but did not prevent the decrease of 5′D-I activity in either liver or kidney. In vitro studies with liver microsomes showed that Irganox is a specific non-competitive inhibitor of 5′D-I activity, with a Ki of 12 μmol/l. These studies suggest that Irganox, by inhibiting 5′D-I activity, can effect thyroid hormone monodeiodination followed by changes of mRNA levels of some thyroid hormone-dependent target genes.
Potential role for arachidonic acid and eicosanoids in modulating progesterone secretion by ovine chorionic cells
Authors: Llosa-Hermier MP de la , Fernandez C , Martal J , Hermier C
Published: June 2009

The present study was conducted to investigate whether arachidonic acid and its metabolites can modulate progesterone (P4) secretion in ovine chorionic cells. At concentrations of 7.5 μmol/l and 12.5 μmol/l, arachidonic acid caused an increase of basal P4 secretion (about 1.8-fold (p< 0.01) and 2.5-fold (p<0.001), respectively, over control). Such a stimulatory effect was suppressed when the concentration of arachidonic acid attained 25 μmol/l, and at 50 μmol/l the fatty acid led to a decline of basal P4 synthesis (about 35%, p <0.01). Phospholipase A2 (PLA2) and melittin had a similar dual effect to that observed when arachidonic acid was added exogenously. In contrast, eicosatrienoic acid (a closely related fatty acid) did not stimulate P4 secretion but inhibited it at a concentration of 50 μmol/l (about 40% inhibition, p <0.01). The possible involvement of calcium on the effects of arachidonic acid was explored. Interestingly, 3 mmol/l ethylene glycol bis(β-aminoethyl ether)-N,N,N,N′-tetraacetic acid (EGTA) and 10 μmol/l 8-N, N-diethylamino-octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8) further enhanced the steroidogenic effect of 12.5 μmol/l arachidonic acid (p<0.05 and p<0.01 vs the corresponding value in the absence of EGTA or TMB-8, respectively). In contrast, these agents failed to modify P4 secretion observed in the presence of 50 μmol/l arachidonic acid. We also tested the effect of inhibition of arachidonic acid metabolism via cyclooxygenase and lipoxygenase pathways. Indomethacin (10 μmol/l) failed to block the effects of arachidonic acid, but nordihydroguaiaretic acid (10 μmol/l) prevented the stimulatory action of this fatty acid. Taken together, these data suggest that arachidonic acid and its metabolites (perhaps its lipoxygenated metabolites) may be important intracellular regulators of P4 secretion in ovine chorionic cells.
Effect of different types of stressors on peptide messenger ribonucleic acids in the hypothalamic paraventricular nucleus
Authors: Ceccatelli Sandra , Orazzo Catello
Published: June 2009

Using in situ hybridization we have studied the effects of different types of stressors, such as ether, immobilization, cold and swimming, on the expression of several peptide messenger ribonucleic acids (mRNAs) in the hypothalamic paraventricular nucleus of adult male rats. Paraventricular nucleus sections were hybridized using synthetic oligonucleotide probes complementary to mRNA for corticotropin-releasing hormone, neurotensin, enkephalin and thyrotropin-releasing hormone. A clear upregulation of neurotensin mRNA was seen after ether and, to a lesser extent, after immobilization stress, whereas after the two other stressors neurotensin mRNA was undetectable, as in control rats. An increase in enkephalin mRNA was observed in a selective region of the dorsal part of the medioparvocellular subdivision of the paraventricular nucleus only after ether and immobilization stress. No significant changes were seen in corticotropin-releasing hormone and thyrotropin-releasing hormone mRNA levels in any of the experimental paradigms. The present results show selective changes for various peptide mRNAs in the paraventricular nucleus after various types of stress. Significant effects could be demonstrated only on neurotensin and enkephalin mRNA after ether and immobilization stress. This suggests that adaptive changes in the rate of synthesis, processing and transport of the peptide may develop over a longer period of time.
Regulation of phospholipid turnover by steroid hormones in endometrial carcinoma and breast cancer cells
Authors: Krasil'nikov Mikhail A , Shatskaya Valentina A , Kuzmina Zoiya V , Barinov Vladimir V , Letyagin Victor P , Bassalyk Laura S
Published: June 2009

To study the early effects of steroid hormones on cells we investigated the influence of the sex steroids and tamoxifen on phospholipid turnover in endometrial carcinoma and breast cancer cells. Studies were performed on 19 human uterine adenocarcinomas and 29 breast cancer tumors. Progesterone in a final concentration of 10−7 mol/l caused a twofold decrease of 32P incorporation into phospholipids (phosphatidylcholine and phosphoinositides) in 85% of the uterine adenocarcinomas where the progesterone receptor (PR) content was more than 100 nmol/kg and only in 30% of the tumors where the PR content was less than 100 nmol/kg. Treatment of the cells with 10−8 mol/l 1 7β-estradiol or 10−8 mol/l epidermal growth factor led to an increase in 32P incorporation into phospholipids. Analysis of the hormonal responsiveness of 29 human breast cancers showed that 17β-estradiol increased 32P incorporation into phospholipids in 47% of the tumors where the estradiol receptor (ER) content was more than 10 nmol/kg and in 21% of the receptor-negative tumors (ER < 10 nmol/kg) The results show that phospholipid turnover in uterine and breast cells can be regulated by sex steroids.

Treatment of the breast cancer cells with the antiestrogen tamoxifen (10−6 mol/l) led to an increase of 32P incorporation into phosphoinositides and a decrease of 32P incorporation into phosphatidylcholine. Addition of an activator of protein kinase C, i.e. 2 × 10−7mol/l 12-0-tetradecanoylphorbol-13-acetate, weakened the inhibitory effect of tamoxifen on phosphatidylcholine turnover. These findings suggest that tamoxifen action can be mediated via an alteration of the growth signal transducing system.
Involvement of cyclic adenosine monophosphate-dependent protein kinase isozymes in tissue plasminogen activator secretion by rat Sertoli cells stimulated with follicle-stimulating hormone in vitro
Authors: Laurent-Cadoret V , Guillou F , Combarnous Y
Published: June 2009

This study was undertaken to investigate, in freshly isolated rat Sertoli cells, the physiological function of the type I and type II cyclic adenosine monophosphate (cAMP)-dependent protein kinase isozymes in tissue-type plasminogen activator secretion and the regulation of this cAMP process by follicle-stimulating hormone (FSH). Follicle-stimulating hormone-induced tissue-type plasminogen activator secretion depends upon intracellular cAMP levels. The changes in cAMP amounts required to activate maximally the tissue-type plasminogen activator secretion are extremely small, a cAMP threshold having to be reached for triggering the tissue-type plasminogen activator output. Intact Sertoli cells were incubated with combinations of cAMP analogs specific for each cAMP-dependent protein kinase type and complementary in their cAMP binding site on the cAMP-dependent protein kinase regulatory subunits: 8-aminohexylamino-cAMP = type 1, site 1; 8-thiomethyl-cAMP = type II, site 1 and N6-benzoyl-cAMP = types I/II, site 2. This allowed us to activate selectively each cAMP-dependent protein kinase type in a synergistic manner and then to evaluate their respective influence in the specific tissue-type plasminogen activator response. We establish that both of the cAMP-dependent protein kinase types are present and functional; the activity of the type I isozyme is preponderant (60%) in the cAMP-dependent tissue-type plasminogen activator secretion. Likewise, when these cAMP analogs were coupled with endogenously generated cAMP by FSH or forskolin, both of the cAMP-dependent protein kinase types were involved in the tissue-type plasminogen activator production. However, only tissue-type plasminogen activator secretion induced by FSH is mediated predominantly by the type I cAMP-dependent protein kinase, although the type II isozyme sustains an appreciable physiological role in the transmission pathway. We suggest some differences in the pattern of action between FSH and forskolin in Sertoli cells.
Pituitary-gonadal response to gonadotropin-releasing hormone stimulation is enhanced in men after strenuous physical exercise
Authors: Vasankari Tommi J , Kujala Urho M , Taimela Simo , Huhtaniemi Ilpo T
Published: June 2009

The effects of strenuous physical exercise were studied on the pituitary-testicular response to gonadotropin-releasing hormone (GnRH) stimulation and on growth hormone (GH) and cortisol secretion. Eight healthy adult males were injected twice intravenously with 0.1 mg of GnRH at intervals of 21 days. At the time of the first injection (exercise trial) the subjects had been bicycling for 4 h on the road, and at the time of the second injection (rest trial) they had been resting in a sitting position for 4 h. Blood samples were taken before and after the 4-h period and 30, 60 and 120 min after the GnRH injection. Both testosterone and luteinizing hormone (LH) decreased during the exercise by 18% (p=0.037) and 29% (p=0.0028), respectively, but increased after the GnRH injection by 1.4- and 12.9-fold (p=0.0001 for both). The areas under the testosterone and LH response curves after GnRH were significantly larger in the exercise trial than in the rest trial, threefold (p = 0.013) and 1.3-fold (p=0.0007), respectively. Growth hormone and cortisol increased during the exercise trial. In the rest trial, the GnRH injection increased serum GH concentrations (p = 0.02 7). In conclusion, the diminished hypothalamic GnRH secretion seems to be the major cause of the post-exercise decrease in LH and testosterone, but altered sensitivity of the pituitary to GnRH also may be involved. Apparently, the build-up of pituitary LH stores during exercise explains the enhanced LH and testosterone response to GnRH challenge after exercise in comparison to control GnRH challenge.