bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunoreactive epidermal growth factor in mouse digestive organs.
Authors: Joh Takashi , Itoh Makoto , Katsumi Kohei , Yokoyama Toshifumi , Miyamoto Tadahisa , Imai Shinpei , Ikeda Kazuo , Matsusako Kei , Takeuchi Toshihiko , Tada Toyohiro , Kato Taiji , Tanaka Ryo
Published: December 2008

Abstract. A sandwich enzyme immunoassay (ELISA) system for mouse epidermal growth factor (EGF), which has a high sensitivity (500 fg/tube), has been established. It makes it possible to measure minute amounts of immunoreactive EGF in various mouse tissue without pretreatment. The immunoreactive EGF concentrations in digestive tissues of adult mice were much lower than previously reported. A significant sex difference was detected not only in the submandibular gland, but also in the oesophagus and forestomach. Although sialoadenectomy decreased the immunoreactive EGF contents in the alimentary tract to 4.2–23.8% of the pre-operative levels, the duodenal immunoreactive EGF was unaffected. Positive immunostaining was observed in the submandibular and sublingual gland, but not in the other digestive tissues, including the duodenum. These data implied that most of the EGF in the digestive tissues was derived mainly from the saliva and that a small amount of endogenous EGF existed in the duodenum. The physiological role of exogenous salivary EGF in the alimentary tract and the origin of endogenous duodenal EGF are discussed.
Ontogeny of atrial natriuretic polypeptide in the human heart
Authors: Kikuchi Kiyoshi , Nakao Kazuwa , Hayashi Ken , Morii Narito , Sugawara Akira , Sakamoto Makoto , Imura Hiroo , Mikawa Haruki
Published: December 2008

Abstract. To elucidate the developmental changes of atrial natriuretic polypeptide in the human heart, we studied α-human atrial natriuretic polypeptide (α-hANP)-like immunoreactivity (α-hANP-LI) in the extracts from the hearts of three foetuses of 10, 14 and 22 weeks' gestation, a 1-day-old premature infant of 33 weeks' gestation, and two adults. α-hANP-LI levels in the atria of the three foetuses of 10, 14 and 22 weeks' gestation and the premature infant (31.4, 12.2, 9.25 and 15.3 nmol/g, respectively) were comparable to those in two adult atria (16.9 and 13.6 nmol/g). The ventricles also contained α-hANP-LI (0.763 → 0.0818 nmol/g with descending values with increasing gestational age) in the three foetuses and the premature infant although it was undetectable (< 0.0162 nmol/g) in two adult ventricles. The highest α-hANP-LI concentration was observed in the auricles in all the hearts except in the premature infant. The concentration in the right auricle was higher than in the left during foetal life, whereas that in the left was the higher one after birth. High performance gel permeation chromatography coupled with radioimmunoassay revealed that α-hANP-LI in the atria and apexes of the foetuses and the premature infant consisted of αhANP, β-hANP and α-hANP, with γ-hANP being the predominant form. Essentially similar gel filtration patterns were observed in the two adult atria. These results indicate that: 1) ANP appears in human heart tissue early in foetal life; 2) cardiac ventricles also contain ANP in the foetus, and 3) there is probably no difference in posttranslational processing of the precursor molecule in foetal and adult hearts.
Systemic effects of 1,25-dihydroxyvitamin D3 on the pituitary-hypothalamic axis in rats
Authors: Törnquist K. , Lamberg-Allardt C.
Published: December 2008

Abstract. Treatment of rats with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) 0.05 μg/kg per day for three days was without any effect on serum T3, T4 or TSH concentrations, whereas serum PRL increased (20.6 ± 3.8 to 76.2 ± 19.1 μg/l, mean ± sem, N = 7–8; P < 0.01). Increased hypothalamic TRH levels (24.3 ± 3.9 to 45.7 ± 7.8 pmol/g wet weight; P < 0.01) may indicate an effect of 1,25(OH)2D3 on hypothalamic TRH homeostasis. This effect could probably be due to an indirect action of 1,25(OH)2D3, mediated by the increased serum calcium (2.77 ± 0.02 to 3.16 ± 0.08 mmol/l, mean ± sem, N = 7–8; P < 0.001). This assumption was, however, not tested. Neither the pituitary TSH nor PRL was affected. The treatment decreased the serum concentration of 25-hydroxyvitamin D3 (23.0 ± 1.3 to 16.8 ± 2.0 nmol/l, mean ± sem, N = 5–7; P < 0.01) and of 24,25-dihydroxyvitamin D3 (3.2 ± 0.3 to 2.1 ± 0.1 nmol/l, mean ± sem, N = 3–5; P < 0.05). The results show that in this experimental design, 1,25(OH)2D3 has no effect on basal hormone secretion from the pituitary-thyroid axis, and that 1,25(OH)2D3 decreases the synthesis of the vitamin D3 metabolites studied.
Pharmacodynamics of [D-Ser (t-Bu), Des-Gly]GnRH ethylamide (Buserelin®) in 6 normal volunteers.
Authors: Reznik Y. , Winiger B. P. , Aubert M. L. , Sizonenko P. C.
Published: December 2008

Abstract. The disappearance rate of [D-Ser(t-bu)6,des-Gly10]GnRH ethylamide (Buserelin®, HOE 766) was studied in plasma and urine after intranasal (300 μg) or sc (10 μg/kg) administration. A radioimmunoassay for HOE 766 was developed using 125I[D-Trp6,Des-Gly10]GnRH ethylamide as tracer and an antiserum raised against HOE 766. Cross-reaction with native GnRH was only 1.7%. Sensitivity was 1 pg/tube. In 6 male adolescents, the mean plasma HOE 766 concentration (± sem) was 0.46 ± 0.08, 0.50 ± 0.10, 0.28 ± 0.04, 0.24 ± 0.04, 0.13 ± 0.03, and 0.08 ± 0.02 μg/l 30, 60, 90, 120 and 180 min after the intranasal administration, respectively. Concomitant urinary excretion of HOE 766-like material was 9.43 ± 1.96 μg/4 h. There was a good correlation between integrated plasma levels and urinary excretion (r = 0.92). In the same 6 volunteers, the plasma HOE 766 levels were 21.2 ± 3.0, 25.9 ± 0.8, 21.2 ± 0.9, 17.1 ± 0.7, 12.8 ± 1.1, 8.9 ± 0.4, and 5.9 ± 0.8 μg/l 20, 40, 60, 90, 120, 180 and 240 min after sc injection, respectively. The mean urinary excretion was 543 ± 61 μg/4 h. In two girls with precocious puberty treated during 12 to 15 months with intranasal administration of HOE 766, urinary excretion of HOE 766-like material was shown to correlate well with the degree of inhibition of plasma 17β-E2and of plasma LH and FSH responses to a GnRH challenge. Thus, monitoring of HOE 766 in urine appears to be helpful for evaluating of intranasal therapy with a GnRH analog in precocious puberty.
Reduction of serum prolactin after salmon calcitonin infusion in patients with impaired renal function
Authors: Pun K. K. , Varghese Z. , Moorhead J. F.
Published: December 2008

Abstract. The physiological role of calcitonin is still uncertain. Recently human calcitonin gene-related peptide, produced by alternative RNA processing from the calcitonin gene, was shown to have structural homology to salmon calcitonin and probably have a modulator function in the hypothalamus. In this study, salmon calcitonin was infused at a low dose (10 MRC units over 30 min) in seven patients with impaired renal function (51-Cr-EDTA clearance = 34.8 ± 4.8 ml/min) in order to elucidate its effects on PRL secretion. The results show that salmon calcitonin at a subhypocalcaemic dose significantly suppresses PRL secretion by over 40% (P < 0.01) and may be of therapeutic use in the treatment of gonadal dysfunction in chronic renal failure.
2-Hydroxylation and O-methylation of oestrogens by human placenta in vivo
Authors: Berg F. D. , Kuss E.
Published: December 2008

Abstract. Concentrations of unconjugated and conjugated 2-hydroxyoestrogens and their 2-methylethers were determined by radioimmunoassay in serum obtained from the umbilical artery, umbilical vein, retroplacental space, and maternal peripheral vein at the time of delivery. The concentrations of unconjugated 2-hydroxyoestrogens and 2-methoxyoestrogens were found to be significantly higher in the post-placental vessels than in the pre-placental vessels. On the basis of the concentrations measured it was estimated that the placenta secretes about 1.4 nmol/min 2-hydroxyoestrogens and about 1.7 nmol/min of 2-methoxyoestrogens. The present in vivo findings confirm the placental 2-hydroxylase- and catechol-O-methyl-transferase activities previously demonstrated in vitro.
Hormonal profile in pubertal females with chronic renal failure: Before and under haemodialysis and after renal transplantation
Authors: Ferraris Jorge R. , Domene Horacio M. , Escobar Maria E. , Caletti Maria G. , Ramirez Jose A. , Rivarola Marco A.
Published: December 2008

Abstract. The effects of chronic renal failure on the hypothalamic-pituitary-ovarian axis in 25 girls, aged 9.1 to 20.9 years (mean 13.8) were studied. Twelve patients on conservative treatment (group A) had serum creatinine values between 176.8 and 1502.8 μmol/l; 9 patients were on haemodialysis (group B); and 12 patients had received a renal transplant (group C). Tanner stage of breast development was delayed relative to chronological age in 5 out of 18 patients. Serum oestradiol was normal or low when related to pubertal stages in all groups. Serum LH was elevated in group A and B patients, but normal in group C patients. Serum FSH was elevated in 6 out of the 21 patients in group A plus B, and in 2 out of the 12 patients in group C. Serum PRL was elevated in 12/12, 6/8, and 4/11 patients in group A, B, and C respectively. After GnRH administration to 4 patients in group A, 3 showed delayed or absent gonadotropin response; all 4 patients studied in group C showed normal gonadotropin response. The data indicate a decreased E2 secretion, abnormal gonadotropin and PRL levels and a blunted gonadotropin response to GnRH in girls with chronic renal failure. These results seem to indicate an alteration of the hypothalamic-pituitary unit that can be reversed after successful renal transplantation.
Effects of fludrocortisone withdrawal on plasma angiotensin II, ACTH, vasopressin, and potassium in patients with Addison's disease
Authors: Oelkers W. , Bähr V.
Published: December 2008

Abstract. We attempted to answer to the question whether excessive rises in endogenous plasma angiotensin II (All) stimulate ACTH secretion by measuring PRA, All, AVP, ACTH, and cortisol in 8 patients with Addison's disease before and after withdrawal of fludrocortisone substitution. Blood was drawn at 14.30 h, exactly 6½ h after the morning dose of hydrocortisone had been taken. PRA and All were initially higher than normal in 4 patients. After withdrawal of fludrocortisone for 1 or 2 weeks, PRA and All rose markedly in 4 patients (up to 260 ng/l) without concomitant changes in plasma ACTH levels (r = −0.081, All vs ACTH). Changes in plasma cortisol could not have obscured a stimulatory effect of All on ACTH by variable feedback inhibition of ACTH release. The increase in plasma All levels in the 4 patients was larger than that observed in a previous study in normal subjects after rigorous dietary sodium restriction. In all patients, hyperkalaemia developed after fludrocortisone withdrawal, independent of changes in PRA and AII. Rises in PRA, All, and plasma potassium were partially reversed by increased sodium intake and further suppressed by resumption of fludrocortisone therapy. Plasma AVP remained in the normal range after fludrocortisone withdrawal, but was slightly elevated after increasing salt intake without fludrocortisone administration. Conclusions: 1) Rises of endogenous plasma All to levels tenfold higher than normal do not stimulate ACTH release. All is probably not a physiological modulator of ACTH secretion. 2) Mineralocorticoid substitution in Addison's disease should be monitored by plasma potassium measurement. Hyperkalaemia may coexist with normal PRA.
Pancreatic endocrine tumour producing growth hormone-releasing hormone associated with multiple endocrine neoplasia type I syndrome
Authors: Asa Sylvia L. , Singer William , Kovacs Kalman , Horvath Eva , Murray David , Colapinto Nicholas , Thorner Michael O.
Published: December 2008

Abstract. We report the first documentation of GHRH production by a tumour associated with proven multiple endocrine neoplasia (MEN). A 30-year-old woman had hypoglycaemia, hyperparathyroidism, and pituitary adenoma with hyperprolactinaemia. Serum growth hormone elevation was attributed to hypoglycaemia but plasma GHRH was elevated. Subtotal pancreatectomy revealed multiple endocrine tumours and nesidioblastosis. Immunohistochemistry demonstrated insulin, glucagon, and somatostatin in several tumours. GHRH was localized in the largest one and was released from that tumour in vitro. Post-operative plasma GH returned to normal. Excess secretion of humoural factors by one tumour may stimulate growth of other tumours in MEN syndromes. The prevalence of GHRH in MEN-I tumours remains to be established.
Vitamin D3 metabolism in a pig strain with pseudo vitamin D-deficiency rickets, type I
Authors: Kaune Reinhard , Harmeyer Johein
Published: December 2008

Abstract. Vitamin D metabolism was studied in the 'Hannover Pig', a strain which suffers from pseudo vitamin D-deficiency rickets, type I. Animals of this strain are known to be devoid of renal 25-hydroxyvitamin D3-1α-hydroxylase and -24-hydroxylase activities. Pigs with florid rickets and hypocalcaemia were treated with single im injections of 0.25 to 1.25 mg of vitamin D3, doses that have been shown in previous studies to be effective in producing transient healing of rachitic symptoms. The levels of vitamin D3 and its most relevant physiological metabolites in plasma were estimated at intervals before and after this vitamin D3 treatment. Vitamin D3 rose from 14.8 ± 8.1 to 364 ± 190 nmol/l (mean ± sd) 2 to 3 days post injectionem, 25-hydroxyvitamin D3 from 131.0 ± 46.2 to 1068 ± 160 nmol/l within 7 days post injectionem. The 1α,25-dihydroxyvitamin D3 concentration in plasma was elevated from 73.9 ± 25.0 to 281 ± 168 pmol/l 2 to 3 days post injectionem and declined continually from that time. 24R,25-dihydroxyvitamin D3 and 25S,26-dihydroxyvitamin D3 levels after treatment showed different responses in different animals being either elevated or unchanged. Clinical healing of the pigs with these doses of vitamin D3 was attributed to the transient rise of 1α,25-dihydroxyvitamin D3 in plasma. It was assumed that 1α,25-dihydroxyvitamin D3 synthesis takes place under these circumstances in extrarenal tissues.
The influence of structural modification on progesterone and androgen receptor binding of norethisterone. Correlation with nuclear magnetic resonance signals
Authors: Hoppen H.-O. , Hammann P.
Published: December 2008

Abstract. The relative binding affinities (RBA) of eight progestogens structurally derived from 17α-ethinyl-19-nortestosterone (norethisterone) have been estimated a) for the progesterone receptor from human premenopausal endometrium and b) for the androgen receptor in human mammary carcinoma in vitro. Introduction of a methylene group at C-11, a methyl group at C-18, or a double bond between C-15 and C-16 of the norethisterone molecule increases the RBA to the progesterone receptor. As a rough approximation, the substituent effects seem to be additive. RBA to the androgen receptor follows a more complex pattern when norethisterone is structurally modified. An additional methyl at C-18 enhances affinity to the androgen receptor. The double bond between C-15 and C-16 has no effect except when introduced into desogestrel, where it reduces RBA to the lowest value in the study. The methylene group at C-11 increases androgen RBA when present as the only substituent, but reduces androgen RBA when together with any other substituent. The complete assignment of 13C-NMR signals has been achieved for all 8 steroids investigated. The 13C-resonance signal of C-17 shows a correlation with the RBA to the progesterone receptor, and with the progestogen/androgen RBA ratios.
Effects of high-dose ketoconazole treatment on adrenal mineralocorticoid biosynthesis in dogs and rats
Authors: De Coster R. , Coene M. C. , Haelterman C. , Beerens D. , Goeminne N.
Published: December 2008

Abstract. At high doses, ketoconazole blocks both testicular and adrenal androgen biosyntheses and partially inhibits the glucocorticoid production. To investigate the effects of this imidazole derivative on the mineralocorticoid biosynthesis, 7 male mongrel dogs received a single oral dose of 15 mg/kg of ketoconazole or placebo, in a cross-over way. From 2 to 4 h after treatment, an iv infusion of angiotensin II (10 ng/kg per min) was performed. Ketoconazole treatment significantly blunted the aldosterone and cortisol increment, whereas 18-hydroxycorticosterone, corticosterone, 11-deoxycorticosterone (DOC), progesterone, and 17α-hydroxyprogesterone rose to peak concentrations, respectively 2.5-, 6-, 8-, 2.5- and 1.5-fold higher than those observed after placebo administration. Plasma 11-deoxycortisol and renin activity levels remained similar in both groups. On the other hand, 2 × 2 groups of 10 male adult rats each were fed with a normal or a sodium-depleted diet. Of the two sets of groups, one was treated ip with ketoconazole (20 mg/kg twice a day), the other with vehicle solution. In animals on either diet, ketoconazole lowered 18-hydroxycorticosterone and aldosterone concentrations. Plasma DOC rose up to 25-fold in the salt-deprived animals. Serum Na+, Cl−, corticosterone and plasma renin activity remained unaffected by the treatment. These results show that high-dose ketoconazole treatment partially inhibits the biosynthesis of aldosterone by affecting the cytochrome P-45011β. However, this inhibition was detected mainly after angiotensin II or salt-depleted stimulation of the aldosterone production. Also, the renin increase was not modified. Therefore, the accumulation of precursors with mineralocorticoid activity such as DOC might have contributed to the maintenance of a normal ionic homeostasis.
Effects of centrally administered atrial natriuretic peptide on renal functions
Authors: Shoji M. , Kimura T. , Matsui K. , Ota K. , Iitake K. , Inoue M. , Yasujima M. , Abe K. , Yoshinaga K.
Published: December 2008

Abstract. In order to assess the effects of centrally administered atrial natriuretic peptide (ANP) on renal water and electrolytes handling, arterial blood pressure, plasma vasopressin, renin activity, aldosterone, and ANP concentrations, synthetic α-human ANP (α-hANP) was administered intracerebroventricularly at a dose of 2.6 pmol · kg−1 · min−1 for 30 min in pentobarbitalanaesthetized dogs (N = 6). In the control study (N = 6), artificial cerebrospinal fluid was infused. Intracerebroventricular administration of α-hANP increased significantly urine flow from 178 ± 37 to 303 ± 43 μl/min (mean ± sem), sodium excretion from 27.3 ± 8.9 to 54.4 ± 10.5, μmol/min, potassium excretion from 16.1 ± 3.7 to 24.0 ± 5.1 μmol/min, and osmolar and negative free water clearances, accompanied by a significant rise in renal blood flow from 77.0 ± 14.6 to 94.9 ± 16.9 ml/min. Whereas glomerular filtration rate fell significantly, blood pressure and heart rate did not change. Plasma ANP, aldosterone, and PRA did not change significantly during the experiment, but plasma AVP were slightly but significantly decreased from 52 ± 11 to 34 ± 6 nmol/l. On the other hand, these parameters showed no changes in the control study, except a significant fall in glomerular filtration rate and a significant rise in PRA. Thus, it has been confirmed that ANP centrally brings about diuresis, natriuresis, and kaliuresis via some unknown mechanisms independent of the release of these hormones.
Effects of H2-receptor antagonists on prolactin secretion: Specificity and mediation of the response
Authors: Knigge Ulrich , Matzen Steen , Warberg Jørgen
Published: December 2008

Abstract. The effects on prolactin secretion of histamine H2-receptor antagonists infused intracerebroventricularly were studied in urethane anaesthetized male rats. A dose of 1.6 μmol cimetidine stimulated basal prolactin secretion and did not affect the histamine-induced release, whereas 0.4 μmol cimetidine inhibited basal and histamine-stimulated prolactin secretion. 0.1 μmol cimetidine had no effect. The more potent H2-receptor antagonist ranitidine at doses of 0.1, 0.4, 1.6 μmol had no effect on basal prolactin secretion, whereas 0.4 and 1.6 μmol inhibited the histamine-stimulated secretion completely. SKF-92408, a compound resembling cimetidine in chemical structure but devoid of H2-receptor antagonist activity, stimulated basal prolactin secretion at a dose of 1.6 μmol, but had no effect on the histamine-induced release or at a dose of 0.4 μmol. The H2-receptor antagonists metiamide and oxmetidine (1.6 μmol) stimulated basal prolactin secretion and did not prevent the response to histamine. A dose of 0.4 or 1.6 μmol imidazole (the ring structure contained in cimetidine, SKF-92408, metiamide, and oxmetidine) had no effect on basal or histamine-stimulated prolactin secretion. The findings indicate that cimetidine stimulates prolactin secretion by a non-specific action when infused centrally at high doses. In contrast, when infused at lower doses cimetidine inhibits the basal and histamine-stimulated secretion by blockade of H2-receptors. The prolactin-stimulatory action of cimetidine was not due to an H2-agonist effect, since ranitidine did not prevent the response. Cimetidine did not stimulate prolactin secretion via an effect on the dopaminergic system, since the drug had no effect on the dopamine concentration in hypophysial portal blood or in hypothalamic tissue and since inhibition of the dopamine synthesis by α-methyl-p-tyrosine did not prevent the cimetidine-induced prolactin release.
Short-term exposure to insulin-like growth factors stimulates testosterone production by testicular interstitial cells
Authors: De Mellow John S. M. , Handelsman David J. , Baxter Robert C.
Published: December 2008

Abstract. The effect of short-term exposure to the insulin-like growth factors (IGF-I and IGF-II) on testosterone production by rat testicular interstitial cells in primary culture has been examined. Both peptides, when present during a 1-h pre-incubation period, increased human chorionic gonadotropin (hCG)-stimulated testosterone release over the following 16-h period. The effect of exposure to IGFs was most marked on maximally hCG-stimulated testosterone release. Maximal stimulation following IGF exposure was 80– 85% above that seen without IGFs, and the IGF effect was half-maximal at 1.5–2 μg/l of IGF-I or IGF-II. Pre-incubation with IGFs did not alter the concentration of hCG (0.1 μg/l) at which half-maximal stimulation of testosterone release was seen. Increasing cell density had a marked effect on the testosterone production rate per 105 cells, and the stimulatory effect of IGFs was only seen at relatively high cell density (2.8 × 105 cells/ml). Varying the period of pre-incubation with IGFs between 0.5 and 16 h, it was found that a 1-h period gave maximal stimulation. We conclude that a short exposure to IGFs is capable of increasing hCG-stimulated steroidogenesis in Leydig cells, and postulate that this effect may be part of an intratesticular paracrine control mechanism.
Blockade of pro-oestrus LH surge and ovulation by GABA increase in the rat locus coeruleus
Authors: Landa Adriana I. , Donoso Alfredo O.
Published: December 2008

Abstract. The effects of gamma-aminobutyric acid (GABA) increase at the nucleus locus coeruleus (LC) on pro-oestrus LH release and ovulation were evaluated in rats. Local microinjection of the GABA-transaminase inhibitor gamma-vinyl-GABA (GVG) produced 6 h later a marked increase in GABA in the LC. Such action caused a significant decrease of plasma LH levels and prevented the pro-oestrus LH surge. In some animals, plasma prolactin levels were also lowered, but in others its plasma concentrations were high and similar to that in controls. Ovulation did not occur in the rats treated with GVG. In additional experiments, the periventricular gray substance (PGS) close to the locus coeruleus was injected with GVG. Results obtained show a LH surge blockade and failure of ovulation in most of these rats. These findings may be interpreted on the basis of GABA action on rostral LC cells that project to the PGS. The results altogether suggest that through neurons of the locus coeruleus, GABA may exert an inhibitory role in the regulation of LH secretion.
TSH binding proteins in rat and human serum
Authors: Spira O. , Gafni M. , Ben-David C. , Gross J. , Gordon A.
Published: December 2008

Abstract. When serum of hypothyroid rats was fractionated on a Sephadex G-100 column, most of the immunoreactive TSH was found as a front running peak, together with the high molecular weight serum proteins. Similarly, a rTSH preparation (10 mU), chromatographed in the presence of 1 ml of normal rat serum also migrated at the front, however, when a high load of TSH (4.4 U) was added to 1 ml of serum, two immunoreactive peaks were found, suggesting the saturation of the front running fraction. Immunoelectrophoresis and autoradiography of rat or human sera containing the respective 125I-labelled TSHs showed binding of the labelled TSH to IgG, alpha-2-macroglobulin, and to a third unidentified protein, migrating near the albumin line. In order to determine if the bound TSH is biologically active, the high molecular weight protein fraction was separated from hypothyroid rat serum by 45% ammonium sulphate precipitation. Immunoreactivity was determined by RIA and the biological activity was determined, in vitro, by the stimulation of 99Tc uptake by FRTL-5 cells. The 45% ammonium sulphate precipitate contained almost all of the immunoreactivity and the bioactivity of the TSH of whole serum. These results indicate that: a) The endogenous circulating TSH in the hypothyroid rat exists mainly in a protein-bound form and this protein-bound TSH contains most of the hormonal bioactivity of the serum. b) Exogenous TSH binds to serum proteins in euthyroid and hypothyroid rats and in humans. There are three protein fractions in these sera that bind TSH, one of which is an immunoglobulin. The occurrence of TSH binding immunoglobulins may involve autoimmune mechanisms.
An implant of a gonadotropin releasing hormone agonist (buserelin) which suppresses ovarian function in the macaque for 3–5 months
Authors: Fraser H. M. , Sandow J. , Seidel H. , von Rechenberg W.
Published: December 2008

Abstract. Four adult female stumptailed macaque monkeys with regular menstrual cycles and one with irregular cycles and dysfunctional uterine bleeding were treated with a single implant containing 2.6 mg of the GnRH agonist buserelin in a matrix of polylactide/glycolide copolymer (75:25). The implant was used as a cylindrical rod of 0.8 × 0.12 cm and implanted sc in the abdominal wall. The insertion of the implant was followed by a modest rise in serum concentrations of LH and FSH lasting 3–4 days before falling to basal values. The release profile of buserelin from the implant was measured in urine by a radioimmunoassay detecting the intact molecule and its major metabolites. Immunoreactive buserelin in urine was high between days 1–3 after implant after which there was a rapid decline to form a plateau between days 15–70 followed by a further gradual decline. This prolonged release of buserelin suppressed ovulation for a mean of 148 days (range 105–182 days) as indicated by absence of serum progesterone rises. Serum FSH concentrations were low for at least 75 days and during this time serum oestradiol concentrations were uniformly suppressed in all monkeys. Once the buserelin release from the implant declined serum FSH concentrations began to rise. There was a variable delay of 7–60 days before this rise in FSH was associated with stimulation of ovarian oestradiol secretion followed by rises in serum progesterone concentrations indicative of ovulation. Apart from the first menses after insertion of implant, 4 of the monkeys became amenorrhoeic for the period of anovulation. The remaining monkey had dysfunctional uterine bleeding prior to treatment and this gradually decreased before disappearing 7 weeks after implant. These results show that this buserelin implant can provide sustained release of peptide to suppress pituitary-ovarian function in the macaque for at least 3 months. Such an implant should provide an important addition to the currently available modes of administration for the clinical use of GnRH agonists.
Effect of anaesthetics on PRL and LH secretion in rats
Authors: Matzen Steen , Knigge Ulrich , Warberg Jørgen
Published: December 2008

Abstract. General anaesthesia has been reported to interact with neuroendocrine functions leading to large variations in basal and stimulated plasma levels of several hormones, but the findings are often contradictory. In the present investigation we have attempted to clarify the importance of the experimental procedure when evaluating the influence of anaesthetics on the secretion of PRL and LH in male rats. One group of rats (non-adapted) were anaesthetized (ip) with pentobarbital (P), urethane (U), ketamine (A), or althesin (A) without being accustomed to the laboratory environment prior to anaesthesia. Another group of rats (adapted) were kept for 90 min in their individual cages before induction of anaesthesia with P or U. In non-adapted rats the plasma concentration of PRL declined rapidly during the first 30 min following administration of all anaesthetics or saline (controls) and attained a steady level after 60 min. Except for a brief rise following U injection, the LH concentration was not affected by anaesthesia in the non-adapted rats. In adapted rats, the concentration of both PRL and LH declined markedly during the pre-anaesthetic adaptation period and had stabilized at the end of that period. Following administration of U, P or saline, no further changes in the hormone concentrations were observed. Injection of the dopamine receptor antagonist pimozide prevented the decrease in plasma PRL during the adaptation period, but had no effect on LH secretion. In pimozide-treated rats, U caused a 5-fold increase in the PRL concentration. This effect of U was inhibited by the serotonin receptor antagonist methysergide. The PRL response to 30 μg of histamine was similar in conscious and U-anaesthetized rats, whereas P anaesthesia caused a reduction in the response. It is concluded that the anaesthetics used here have no significant influence on the basal secretion of PRL and LH, and that the change in PRL secretion observed in non-adapted animals is not caused by the anaesthetic agents, but is due to the routine manipulation of the animals preceding induction of anaesthesia. We recommend that neuroendocrine experimentation be not initiated until 60 min after administration of anaesthetics.
The cellular mechanism of the antiandrogenic action of nomegestrol acetate, a new 19-nor progestagen, on the rat prostate
Authors: Botella Jacqueline , Paris Jacques , Lahlou Brahim
Published: December 2008

Abstract. Nomegestrol acetate, like other synthetic progestins such as medroxyprogesterone acetate (MPA), chlormadinone acetate, megestrol acetate and cyproterone acetate, is able to modify the physiological actions of androgens. In the present study, the effects of nomegestrol acetate and other antiandrogens on the binding of androgen to the androgen receptor (AR) and on the 'activation' of this receptor were investigated, using rat ventral prostate as target model. Relative binding affinities (RBA) for AR were first estimated in vitro with respect to [3H]testosterone for a series of structurally-related compounds. The values obtained ranged as follows: dihydrotestosterone (DHT) » megestrol acetate ≥ testosterone (T) > nomegestrol acetate > 19-nor progesterone (19NP) > progesterone (P). An assay was established, using two different incubation times (3 h and 24 h) to further investigate relationships between binding affinity and androgenic, or antiandrogenic, activity. The following order (as %) was obtained for progestins as against [3H]mibolerone (DMNT): 1) DMNT (100) » acetate (42) > megestrol acetate (29) > chlormadinone acetate (9) > MPA (8) > cyproterone acetate (6) after 3 h and 2) DMNT (100) » MPA (53) » nomegestrol acetate (19) > megestrol acetate (12) > chlormadinone acetate (14) and cyproterone acetate (8) after 24 h. Since the RBA of nomegestrol acetate declined with time, these results indicate that this substance may act like an antiandrogen rather than an androgen, while the contrary prevails concerning MPA. The effects of these progestins, administered either alone or in combination with DHT to the animals, on the location (nuclear or cytosolic) of AR were also analyzed. DHT (0.05 or 4 mg/kg) produced maximal nuclear location of AR. Of the progestins tested, only MPA and norethisterone acetate reproduced this effect, while other steroids were ineffective. Furthermore, cyproterone acetate, megestrol acetate and nomegestrol acetate were able to inhibit to a large extent the DHT-elicited effect. The evidence from these studies suggests that the new compound nomegestrol acetate may oppose the actions of androgens on ventral prostate by directly interacting with the androgen receptor.
Effects of substrates for aromatic L-amino acid decarboxylase on insulin secretion
Authors: Lindström Per , Sehlin Janove
Published: December 2008

Abstract. It has been shown that substrates for aromatic L-amino acid decarboxylase potentiate glucose-induced insulin release. Microdissected islets of obesehyperglycemic mice (Umeå ob/ob) have now been used in a study of the effects of decarboxylase substrates on insulin release induced by secretagogues other than glucose. L-5-hydroxytryptophan (L-5-HTP) at 4 mmol/l potentiated the effect of 1 μmol/l glibenclamide, 20 mmol/l D,L-glyceraldehyde or 20 mmol/l K+, but not that of 50 μmol/l chloromercuribenzene-p-sulphonic acid. The potentiating effect of 4 mmol/l L-5-HTP, 4 mmol/l D,L-m-tyrosine, or 4 mmol/l D,L-o-tyrosine on insulin release induced by 20 mmol/l L-leucine was inhibited by 0.1 mmol/l benserazide. Benserazide did not reduce the effect of 10 mmol/l L-glutamine on L-leucine-induced insulin release. L-dihydroxyphenyl-alanine inhibited glucose-induced insulin secretion at 0.1 mmol/l with a tendency towards a reduction also at lower concentrations. The findings support the hypothesis that increased activity of aromatic L-amino acid decarboxylase can stimulate islet B cell function.
Effects of trifluoperazine on prolactin release and cyclic AMP formation and degradation in GH4C1 pituitary cells
Authors: Sletholt Kjersti , Gordeladze Jan , Haug Egil , Gautvik Kaare M.
Published: December 2008

Abstract. In GH4C1 cells, the calmodulin antagonist trifluoperazine (TFP) showed a dose-dependent, biphasic effect on the basal release of PRL. An inhibition of PRL release was observed with 15–50 μmol/l TFP, whereas a concentration of 100 μmol/l and above had a stimulatory effect. The increase in basal hormone release evoked by TRH (1 μmol/l) and high extracellular concentration of K+ (50 mmol/l) was eliminated by 30 μmol/l TFP. The stimulatory effect of 100 μmol/l TFP on basal hormone release was not affected by addition of TRH (1 μmol/l) or K+ (50 mmol/l). The Ca2+ antagonists Co2+ (5 mmol/l) and verapamil (100 μmol/l), and the Ca2+ chelator EgTA (4 mmol/l) abolished the stimulatory effect of TRH (1 μmol/l) and of K+ (50 mmol/l on PRL release, whereas only Co2+ inhibited the stimulation caused by 100 μmol/l TFP. TFP (75 μmol/l) caused a transient increase in the concentration of cellular cAMP. Incubation of intact GH4C1 cells with TFP (75 μmol/l), had an inhibitory effect on both the low and the high affinity form of cAMP phosphodiesterase. Basal as well as TRH-stimulated adenyl cyclase activity were inhibited by TFP, and this effect was counteracted by addition of calmodulin.
Lowering of serum T3 and rise in reverse T3 induced by glucagon infusion in anaesthetized dogs
Authors: Kabadi Udaya M. , Dragstedt Lester
Published: December 2008

Abstract. We recently demonstrated that lowering of T3 and a rise in rT3 observed in non-thyroidal illnesses could be induced by glucagon infusion in normal subjects without altering T4, Free T4 (FT4) and T3 resin uptake (T3RU) values suggesting that altered T4 metabolism may be mainly responsible for those changes. To further assess the role of altered T4 metabolism in these changes during induction of hyperglucagonaemia, we studied glucose, T4, FT4, T3RU, T3, and rT3 concentrations before and after iv glucagon injection (0.5 mg) for up to 3 h in 6 anaesthetized dogs, since thyroxinebinding globulin (TBG) concentration is known to be extremely low in dogs. A control study was conducted with iv normal saline (0.5 ml) injection. T4, FT4 and T3RU remained unchanged during both studies. A significant fall was noted in T3 with glucagon (ΔT3, 0.23 ± 0.06 nmol/l vs 0 ± 0.03 nmol/l with normal saline; P < 0.01). rT3 rose markedly following glucagon infusion (ΔrT3, 0.04 ± 0.011 nmol/l vs −0.017 ± 0.006 nmol/l with normal saline; P < 0.01). Moreover, areas under the curves for T3 and rT3 were markedly increased during glucagon infusion when compared to saline administration (P < 0.01 for both comparisons). Therefore, this study suggests that changes in T3 and rT3 concentrations observed in non-thyroidal illnesses may be attributed to hyperglucagonaemia and may be secondary to altered T4 metabolism as reflected by lowered T3/T4 and increased rT3/T4 ratio.
Growth hormone responses to the releasing hormones GHRH and GnRH and the inhibitors somatostatin and bromocriptine in TRH-responsive and non-responsive acromegalics
Authors: Smals A. E. M. , Pieters G. F. F. M. , Smals A. G. H. , Hermus A. R. M. M. , Benraad Th. J. , Kloppenborg P. W. C.
Published: December 2008

Abstract. In acromegalics, the percent peak GH responses to TRH (pTRH) and bromocriptine (pBr) are inversely related with those to GHRH, favouring the hypothesis that in the adenomas of some patients there is a preponderance of GH-producing cells with lactotrope-like characteristics, whereas in others pure somatotropes predominate. The aim of the present study was to investigate whether patients responsive to TRH with allegedly lactotrope-like tumours differ from those patients not responding to TRH with more somatotrope-like adenomas in their answer to the GH inhibitors Br and SRIH and the releasing hormones GHRH and GnRH. The present study demonstrates that the observed reciprocal relations between the GH responses to GHRH, TRH and Br are only present in acromegalics paradoxically responding to TRH (pGHRH vs pTRH −0.73, pGHRH vs pBr −0.60, pTRH vs pBr +0.54, P < 0.0002–P < 0.02, N = 20), not in TRH-non-responders (N = 10). In contrast, in these latter patients, not in the former, close relations were found between the percent peak GH responses to GnRH (pGnRH) and pGHRH (r = +0.81, P < 0.005) and between pGnRH and the percent maximum GH decrements in response to SRIH (pSRIH) (r = +0.64, P < 0.05). Expectedly, the GH response to Br in the TRH-responders was significantly higher than in the non-responders (75 ± 4% vs 54 ± 3%, P < 0.02), although it was also substantial in the latter. The GH response to SRIH was remarkedly similar in both groups (64 ± 5 vs 57 ± 9%, P > 0.10). Although the close relations between the GH responses to releasing and inhibiting agents favour the presence of GH-secreting tumours with more somatotrope or more lactotrope characteristics in subsets of acromegalics, they do not effectively predict the therapeutic response to these suppressive agents.
Growth hormone, insulin, glucose, cortisol, luteinizing hormone, and diabetes in beagle bitches treated with medroxyprogesterone acetate
Authors: McCann Joseph P. , Altszuler Norman , Hampshire Jennifer , Concannon Patrick W.
Published: December 2008

Abstract. Adult beagle bitches (20 to 101 months old) received medroxyprogesterone acetate (MPA; 75 mg/kg, im) or control vehicle at 3 month intervals. Changes in serum concentrations of GH, insulin and glucose were determined in 18 MPA-treated and 6 of 12 control bitches at 0, 2, 4, 8, 16 and 17–24 months of treatment (Exp. I). GH, LH and cortisol responsiveness to combined im injection of TRH (10 μg/kg), GnRH (10 μg/kg), and ACTH (5 μg/kg) was determined in 9 MPA-treated and 9 control bitches at 17 months of treatment (Exp. II). In Exp. I, serum concentrations of GH at month 2 (2.6 ± 0.3 μg/l), 4 (3.0 ± 0.3 μg/l), 8 (4.0 ± 1.2 μg/l), 16 (8.5 ± 1.7 μg/l), and 17–24 (21.2 ± 4.1 μg/l) of treatment were greater (P < 0.05) than pretreatment (1.4 ± 0.07 μg/l) and control (1.5 ± 0.1 μg/l) levels. The increase in GH at 2 months preceded (N = 4) or coincided (N = 2) with the development of hyperinsulinaemia and insulin resistance in 6 of the 18 treated bitches, two of which became diabetic by 17 months of MPA treatment. GH (24.6 ± 5.0 vs 11.4 ± 2.1 μg/l) and insulin (308 ± 77 vs 119 ± 9 pmol/l) concentrations were greater (P < 0.05) in older (49 ± 4 months; N = 12) than in the younger (26 ± 2 months; N = 6) treated bitches at 17–24 months of MPA treatment. In Exp. II, pretreatment concentrations of GH were increased (9.8 ± 3.0 vs 1.4 ± 0.1 μg/l, P < 0.01), cortisol levels decreased (12 ± 5 vs 72 ± 10 nmol/l, P < 0.01) and LH concentrations (0.9 ± 0.2 μg/l) unaffected in MPA-treated bitches. After injection of tropic hormones, GH was unchanged, whereas the rises in LH and cortisol levels were less (P < 0.01) in MPA-treated bitches than in control bitches. The results demonstrate that high doses of MPA increase GH concentrations within 2 months and that the GH overproduction and its diabetogenic-like effects were more pronounced in the older than in the younger treated bitches.
Effect of GnRH-associated peptide on prolactin secretion from human lactotrope adenoma cells in culture
Authors: Ishibashi Miyuki , Yamaji Tohru , Takaku Fumimaro , Teramoto Akira , Fukushima Takanori , Toyama Makoto , Kamoi Kyuzi
Published: December 2008

Abstract. The effect of GnRH-associated peptide on PRL secretion by human pituitary lactotropes in culture was studied. Pituitary adenomas obtained at selective transsphenoidal adenomectomy from a patient with prolactinoma, and two patients with mixed GH- and PRL-secreting pituitary adenomas were cultured in monolayer. When cells were incubated with dopamine (10 nmol/l), a significant inhibition in PRL secretion was observed in all the experiments, which was blocked by co-incubation with haloperidol. In mixed GH- and PRL-secreting adenoma cells, dopamine likewise decreased GH secretion. Incubation of cells with synthetic GnRH-associated peptide at concentrations up to 100 nmol/l, on the other hand, failed to affect both PRL and GH secretion. These results suggest that synthetic GnRH-associated peptide has no inhibitory effect on PRL secretion in human pituitary lactotropes.
Circulating blood progesterone is pulsatile throughout the rat oestrous cycle
Authors: Park Ok-Kyong , Ramirez Victor D.
Published: December 2008

Abstract. In the present experiment, we determined circulating progesterone (P4) levels of intact cycling female rats. A cannula constructed from polyethylene50 tubing containing heparinized saline was inserted into the jugular vein of the rat under light ether anaesthesia and after a 3–6 h recovery period sequential blood samples were withdrawn from unanaesthetized, freely-moving rats. Blood samples (80–100 μl) were collected at 10-min intervals for 6 h and the volume was replaced with saline. Plasma P4 was determined using a specific P4 radioimmunoassay. Four rats in each of three phases of the rat oestrous cycle (E, Dl, D2) were examined. In addition, rats in proestrus were divided into an early (EP, N = 4) and a late (LP, N = 4) proestrous conditions. Individual data were analyzed by PULSAR as adapted for an IBM-PC. P4 was found to fluctuate in a pulsatile mode throughout the rat oestrous cycle. Mean levels of circulating P4 were lowest (38.8 ± 1.7 nmol/l plasma) in EP and highest (122.5 ± 1.3) in Dl. The frequency of P4 pulses was dramatically decreased in Dl (2.50 ± 0.86 pulses/6 h), whereas no difference was found among the other days of the cycle (7.25 ± 0.47 in E, 7.25 ± 0.85 in D2, 5.75 ± 1.31 in EP, and 6.50 ± 1.04 in LP). Interestingly, the amplitude of P4 pulses was significantly lower in EP (14.0 ± 2.91 pmol), whereas no difference was found among other groups. Another group of experimental animals were ovariectomized (N = 4; two with and two without an implant of a silastic capsule of P4) and similarly bled. These animals demonstrated a fairly stable circulating pattern of P4. The present data demonstrate for the first time that P4 in rat blood fluctuates in a pulsatile manner.
The biological activity of different molecular forms of ACTH on corticosterone production by perifused foetal rat adrenal glands in vitro
Authors: Chatelain Alain , Cheong Hee-Seung
Published: December 2008

Abstract. The responsiveness of perifused adrenal glands removed from rats at various stages of gestation to similar immunological quantities (2 ng) of 'big' (≅ 30 000 mol wt), 'intermediate' (≅ 13 000 mol wt) and 'little' (≅ 4500 mol wt) ACTH isolated by gel filtration chromatography from an acid extract of pituitary glands of 21 day-old rat foetuses was determined. This immunological quantity failed to induce a maximal response of the foetal adrenals. Cortisosterone was determined in the effluent perifusion by a radiocompetition assay. On days 17 and 19 of gestation, intermediate and little ACTH had, on a weight basis, the same corticosteroidogenic activity, but on day 21 the little was more potent than the intermediate form. The corticosterone release by these two forms of ACTH was log-dose dependent. The biological activity of big ACTH was very low on day 17, slightly increased until day 21 but remained significantly lower than that of intermediate and little forms. Big ACTH added to little ACTH in the perifusion medium did not modify the corticosteroidogenic activity of little ACTH on days 17, 19 and 21 of gestation.
Oestrogen dependent suppression of mitogen response in rat lymphocytes
Authors: Mckenzie Christopher E. , Berczi Istvan
Published: December 2008

Abstract. Female Fischer rats have a significantly (P < 0.01) lower response to mitogens (phytohaemaglutinin and pokeweed mitogen) in whole blood cultures, than do male. In vitro cultures were carried out in 96-well micro-test plates with 5% blood over a period of 64 h, with a pulse of [3H]thymidine at 48 h. Ovariectomy resulted in a significant (P < 0.01) increase in mitogen response, raising it to the level of normal males. Orchidectomy caused a small, but consistent rise in response. Injection of oestradiol valerate (at 0.5 mg/week, to yield physiological levels) suppressed the response of gonadectomized animals of both sexes to the level of normal female rats. Testosterone oenanthate had little effect unless administered in conjunction with oestradiol valerate, when a much greater depression of response was noted. Suppressor cells, or suppressive serum factors, could not be detected in the blood of normal females or oestrogen-treated animals during in vitro mixing experiments. Although it required 3 weeks for the ovariectomized animals' response to rise to the level of normal males, only 3 days of oestradiol valerate treatment was necessary to suppress the response again. Whereas it seems clear that oestradiol is responsible for the suppressed response of female Fischer rats, its mechanism of action has not been revealed by our experiments.