bluuebunny/crossref_metadata_2025_split huggingface dataset:
Peptides related to α-melanocyte-stimulating hormone are commonly produced by human pituitary corticotroph adenomas: no relationship with pars intermedia origin
Authors: Coates P. J. , Doniach I. , Wells C. , Hale A. C. , Rees L. H. , Besser G. M. 
Published: December 2008

ABSTRACT
The presence of immunoreactive (ir)-α-MSH has been investigated by immunocytochemistry in 24 pituitary adenomas and one case of corticotroph hyperplasia causing Cushing's disease, in four adenomas causing Nelson's syndrome, and in ten 'silent' corticotroph adenomas. It was found that a high proportion of these adenomas have a population of cells containing ir-α-MSH in addition to ir-ACTH. In some instances, these adenomas were clearly not associated with the residual intermediate lobe of the pituitary. Radioimmunoassay of plasma from patients with Cushing's disease or Nelson's syndrome showed elevated levels of ir-α-MSH in the majority of cases. Characterization of the ir-α-MSH in adenoma cells by immunocytochemistry, using an antiserum selective for acetylated forms of α-MSH, suggested that only the desacetyl form was present in each case examined. High-performance liquid chromatography of adenoma tissue extracts revealed material co-eluting with acetylated forms of α-MSH in only one of six cases. These results have been compared with corticotroph adenomas in animal pituitary glands, and it is concluded that the presence of α-MSH peptides cannot be used as a marker for intermediate lobe tumours, and that desacetyl α-MSH is commonly produced by corticotroph adenomas.
Journal of Endocrinology (1989) 120, 531–536
In-vivo effect of ethanol on release of LH-releasing hormone and LH in rats
Authors: Emanuele M. A. , Tentler J. , Reda D. , Kirsteins L. , Emanuele N. V. , Lawrence A. M. 
Published: December 2008

ABSTRACT
The effect of exposure to ethanol on hypothalamic LH-releasing hormone (LHRH) release in vivo was investigated in rats both acutely (i.p. injection) and after 3 days of administration, utilizing a permanent gastric cannula. In both designs, the animals were castrated before being given ethanol and, in both experiments, ethanol successfully lowered the post-castration LH rise compared with control castrated animals. In both the acutely and chronically treated groups, basal LHRH release was not impaired, despite the documented decrease in LH levels. Finally, stimulated LHRH release was investigated with depolarizing concentrations of potassium and, again, no change was noted between the hypothalamic release of this decapeptide in the ethanol-exposed compared with the ethanol-naive animals. Thus, ethanol failed to inhibit basal or stimulated LHRH secretion in the acutely and chronically treated animal. This lack of effect on LHRH occurred despite a concomitant lowering of serum concentrations of LH.
Journal of Endocrinology (1989) 121, 37–41
Plasma concentrations of cholecystokinin octapeptide and food intake in male rats treated with cholecystokinin octapeptide
Authors: Lindén A. , Uvnäs-Moberg K. , Forsberg G. , Bednar I. , Södersten P. 
Published: December 2008

ABSTRACT
Intraperitoneal injection of 5 μg cholecystokinin octapeptide (CCK-8) into male rats deprived of food for 48 h produced a transient (less than 15 min) increase in plasma levels of CCK-8 but suppressed food intake for an extended period (45 min). Plasma concentrations of CCK-8 after i.p. injection of CCK-8 were raised to levels which were fairly comparable to those after feeding. Intracerebroventricular (i.c.v.) injection of the CCK antagonist proglumide (100 μg) reversed the effect of CCK-8 on food intake, while i.p. injection of proglumide (100 μg) did not have this effect. Feeding increased the plasma concentrations of somatostatin and gastrin but not of oxytocin, and somatostatin and oxytocin but not gastrin were released in response to i.p. injection of CCK-8. However, neither somatostatin nor oxytocin affected food intake, and their release in response to CCK-8 was unaffected by i.c.v. injection of proglumide. These results support the suggestion that CCK-8 is a physiological 'satiety' peptide, which can affect food intake in rats by mechanisms involving both peripheral and central CCK receptors.
Journal of Endocrinology (1989) 121, 59–65
Changes in serum concentrations of immunoreactive inhibin during the oestrous cycle of the rat
Authors: Hasegawa Y. , Miyamoto K. , Igarashi M. 
Published: December 2008

ABSTRACT
Serum and ovarian concentrations of inhibin during the oestrous cycle of rats were determined by a radioimmunoassay (RIA) based on a porcine inhibin RIA. Serum concentrations of LH, FSH, oestradiol-17β, progesterone and testosterone were also determined during the cycle. Serum concentrations of inhibin were high (8·47 ± 0·58 μg/l) during the morning of pro-oestrus and then dropped sharply to the lowest level (3·21 ± 0·38 μg/l) at 24.00 h on the day of pro-oestrus after the preovulatory LH and FSH surge. Inhibin concentrations then recovered rapidly, with a peak (7·94 ± 0·97 μg/l) at 15.00 h on the day of oestrus. Inhibin concentrations in serum dropped again to their second lowest value (4·00 ± 0·12 μg/l) at 24.00 h on the day of oestrus. The largest FSH surge observed from midnight of pro-oestrus to the morning of oestrus (the so-called second FSH surge) was shown to be inversely related to the changes in serum concentrations of inhibin, suggesting a close relationship between the serum FSH and inhibin concentrations in cyclic rats.
Journal of Endocrinology (1989) 121, 91–100
Effects of cholesterol and lipoproteins on aldosterone secretion by bovine zona glomerulosa cells
Authors: Simpson H. D. , Shepherd R. , Shepherd J. , Fraser R. , Lever A. F. , Kenyon C. J. 
Published: December 2008

ABSTRACT
Freshly isolated bovine adrenocortical cells were pretreated with various concentrations of cholesterol and of high- (HDL) and low-density lipoprotein (LDL) fractions of known cholesterol content and then incubated in medium alone with and without angiotensin II. Preincubation with cholesterol (323 μmol/l) caused basal aldosterone synthesis to increase from 0·89 ± 0·08 to 2·77 ± 0·22 pmol/106 cells per hour (±s.e.m.) but did not significantly affect angiotensin-stimulated synthesis. Human HDL containing cholesterol at a final concentration of 129–647 μmol/l increased both basal and angiotensin-stimulated aldosterone synthesis. In HDL-treated cells, both the threshold response and responses to increasing concentrations of angiotensin were raised. Human LDL had no effect on basal or stimulated aldosterone synthesis nor did LDL alter the effects of HDL when cells were incubated with HDL and LDL in combination. Qualitatively similar results were obtained with bovine lipoproteins.
These studies show that, in short-term incubations of fresh tissue, the supply of cholesterol may be a limiting factor in aldosterone synthesis and that HDL rather than LDL is the preferred source. These observations are discussed in relation first to the mechanisms by which cholesterol/HDL might augment steroid responses and secondly to other studies with cultured cells which have demonstrated a role for LDL.
Journal of Endocrinology (1989) 121,125–131
LH in polycystic ovary syndrome: reproducibility and pulsatile secretion
Authors: Murdoch A. P. , Diggle P. J. , White M. C. , Kendall-Taylor P. , Dunlop W. 
Published: December 2008

ABSTRACT
Serum concentrations of LH are increased in polycystic ovary syndrome (PCOS). We have investigated two aspects of LH secretion which have not previously been reported: its reproducibility within individuals and the pattern of superimposed pulses of LH secretion. In nine patients with PCOS the mean concentration of LH was calculated from 24 blood samples taken at 15-min intervals for 6 h on two or three occasions over 1 year. Results showed differences in mean LH between subjects but reproducible concentrations within subjects over that period. It has been shown that LH is secreted in a complicated pattern of superimposed pulses which can be characterized by using the statistical methods of time-series analysis. To evaluate these pulse patterns of LH we studied nine patients with PCOS and compared the results with those of 12 normal women in the early follicular phase of the ovarian cycle. Blood samples were taken at either 5-min intervals for 6 h or 1-min intervals for 1 h. Pulses were detected in both groups at frequencies of about 1 h and 2 to 3 min. There was no significant difference in the pulse frequencies between the patients and controls but the amplitude of both groups of pulses was increased in the PCOS patients.
Journal of Endocrinology (1989) 121, 185–191
Macrophage activation enhances the human chorionic gonadotrophin-induced disruption of spermatogenesis in the rat
Authors: Kerr J. B. , Sharpe R. M. 
Published: December 2008

ABSTRACT
The objective of this study was to examine the role of intertubular macrophages in modifying the response of the rat testis to stimulation by human chorionic gonadotrophin (hCG). The phagocytic activity of macrophages was stimulated by a unilateral intratesticular injection of polystyrene latex beads. Latex beads were engulfed by the resident macrophages and retained within their cytoplasm. Contralateral testes received injection of vehicle alone. A group of control rats was killed 3 days later; other groups received 100 IU hCG s.c. and the morphological and functional responses of the testes were examined 12, 24 and 48 h later. Spermatogenesis was unaffected in control rats, whereas in the testes of all hCG-treated rats leukocytes infiltrated into the intertubular tissue and the seminiferous tubules exhibited focal disruptions of spermatogenesis which were more severe in testes containing activated macrophages. Spermatogenic disruption was dependent upon the stage of the spermatogenic cycle, with the maximum tubule degeneration occurring at or near stages III and IX–XI. However these changes were not a consequence of androgen deprivation, since no consistent correlation was demonstrated between alterations in testosterone levels in testicular interstitial fluid and the accompanying damage to germ cells. It is concluded that hCG alone or in combination with activated macrophages induces an inflammatory-type response of the intertubular tissue and localized degeneration of the seminiferous epithelium. The antispermatogenic effects of hCG may have important implications for in-vivo investigations of Leydig cell function in laboratory animals and for the efficacy of hCG administration used in the clinical treatment of male hypogonadism.
Journal of Endocrinology (1989) 121, 285–292
Effect of the glycogenolytic gluconeogenetic hormones, glucagon, vasopressin and angiotensin II, on biliary excretion of iodothyronines in rats is possibly related to the inhibition of 5′-monodeiodination in the liver
Authors: Langer P. , Földes O. , Gschwendtová K. 
Published: December 2008

ABSTRACT
Polyethylene tubes were inserted into the bile duct and femoral vein of rats under pentobarbital anaesthesia and bile was collected for three 2-h periods. After the first (control) period the animals were infused intravenously at a rate of 1·2 ml/h with the following compounds: (1) 0·9% (w/v) NaCl (control group), (2) glucagon (1200 ng/h), (3) vasopressin (1200 ng/h) or (4) angiotensin II (600 ng/h). The concentrations of thyroxine (T4), tri-iodothyronine (T3) and reverse tri-iodothyronine (rT3) in the bile were estimated by radioimmunoassay. No significant differences between groups were found in the biliary excretion of T4 and T3, while the excretion of rT3 after the infusion of all the hormones used was significantly (P < 0·001 at 2 to 4 h of the infusion) increased, no such increase being found in the controls. It may be concluded therefore that the administration of the above hormones resulted in some changes in iodothyronine metabolism in the liver. These may be explained by an inhibition of iodothyronine 5′-monodeiodination related to the glycogenolytic and gluconeogenetic effects of these hormones.
Journal of Endocrinology (1989) 121, 299–302
Effect of a single injection of human chorionic gonadotrophin on testosterone levels in testicular interstitial fluid, and in testicular and peripheral venous blood in adult rats
Authors: Maddocks S. , Setchell B. P. 
Published: December 2008

ABSTRACT
We have used a push–pull cannula to collect interstitial fluid from the testes of anaesthetized rats at various times after a single injection of human chorionic gonadotrophin (hCG; 50 IU), and compared the levels of testosterone in this fluid with the levels in testicular and peripheral venous blood collected at the same times. Following hCG injection, significant increases in testosterone concentrations were observed in all fluids with notable peaks occurring in interstitial fluid at 2, 8 and 24 h, in testicular venous blood at 2, 8 and 30 h, and in peripheral venous blood at 2, 8, 24 and 72 h. The results demonstrate for the first time that changes in testosterone concentrations in interstitial fluid can be different from those in testicular venous blood. In addition, when testosterone levels in interstitial fluid were compared with levels in testicular venous blood at each time-point, the results suggested that the partitioning of testosterone between these two compartments can be regulated. Furthermore, the changes in both interstitial fluid and testicular venous blood levels of testosterone do not always parallel those in peripheral venous blood, suggesting that changes in testicular blood flow and peripheral clearance rates of testosterone may also be important in the control of circulating testosterone concentrations.
Journal of Endocrinology (1989) 121, 311–316
Possible role of histones in the organization of rat liver thyroid hormone receptors in chromatin
Authors: Sakurai A. , Ichikawa K. , Hashizume K. , Miyamoto T. , Yamauchi K. , Ohtsuka H. , Nishii Y. , Yamada T. 
Published: December 2008

ABSTRACT
The effects of histone subfractions on rat liver thyroid hormone receptor–DNA interaction were examined using an in-vitro DNA-cellulose binding assay. H1 histones bound to DNA showed reversible and potent inhibition of receptor–DNA binding without affecting receptor–hormone binding. Poly-lysine, bovine serum albumin, ovalbumin and cytochrome c did not alter receptor–DNA binding. H1 histone subfractions (calf thymus lysine-rich histone (CTL)-1, CTL-2 and CTL-3) showed potent inhibition of receptor–DNA binding indistinguishable from each other. The quantity of H1 histone subfractions bound to DNA was the same. Although each subfraction has different functional properties, inhibition of receptor–DNA binding was a common feature of all the H1 histone subfractions, which is important for the non-random distribution of the receptor in chromatin.
Binding of the receptor to core histones was investigated; it was found to bind to core histones more potently than to other proteins (H1 histone, ovalbumin and cytochrome c). Among core histone subfractions, H4 histone bound to the receptor most potently and is the candidate to be one of the acceptor sites of the receptor in chromatin.
Journal of Endocrinology (1989) 121, 337–341
Inhibition of arginine vasopressin-stimulated Na+K+ATPase activity by difluoromethyl ornithine in the rat renal medulla
Authors: Charlton J. A. , Baylis P. H. 
Published: December 2008

ABSTRACT
Arginine vasopressin (AVP) stimulates Na+K+ ATPase and ornithine decarboxylase (ODC) activity in the rat medullary thick ascending limb. The effect of difluoromethyl ornithine (DFMO), a specific inhibitor of ODC activity, on AVP-stimulated Na+K+ATPase activity was evaluated using a cytochemical bioassay. Peaks in Na+K+ATPase activity in cultured rat renal segments which occurred after tissue had been exposed to 1 fmol AVP/l were completely inhibited by the addition of 20 mmol DFMO/l to the culture medium containing AVP. The addition of 20 mmol DFMO/l to the culture medium containing AVP in the concentration range 0·001–10 fmol/l inhibited completely the stimulation of Na+K+ATPase activity by AVP. The response of Na+K+ATPase to increasing doses of ATP (10–40 g polypeptide/l) was not influenced by the addition of 20 mmol DFMO/l to the culture medium containing AVP, suggesting that the prevention of AVP-stimulated Na+K+ATPase activity by DFMO was not due to a direct effect on the enzyme.
Journal of Endocrinology (1989) 121, 435–439
Vitamin D-enhanced thyrotrophin release from rat pituitary cells: effects of Ca2+, dihydropyridines and ionomycin
Authors: d'Emden M. C. , Wark J. D. 
Published: December 2008

ABSTRACT
Vitamin D may regulate pituitary function, as there are selective effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on gene expression in clonal pituitary tumour cells, and on TRH-induced TSH release in normal rat pituitary cells in vitro. The role of Ca2+ in 1,25-(OH)2D3-enhanced TSH release from primary rat pituitary cell cultures was investigated. Pretreatment with 10 nmol 1,25-(OH)2D3/l for 24 h augmented KCl (3–60 mmol/l)-induced TSH release over 1 h at all KCl concentrations greater than 7·5 mmol/l (P< 0·001), with a 76% enhancement of TSH release induced by 30 mmol KCl/l (P<0·001). The Ca2+ channel antagonist nifedipine (10 nmol/l–10 μmol/l) caused a concentration-dependent inhibition of KCl (60 mmol/l)-induced TSH secretion. Pretreatment with 1,25-(OH)2D3 enhanced KCl-induced release at all concentrations of nifedipine (P<0·001). The Ca2+ selective divalent cation ionophore ionomycin (1 nmol/l–1 μmol/l), and the Ca2+ channel agonist BAY K 8644 (10 nmol/l–1 μmol/l) increased prolactin secretion but did not increase TSH release, and 1,25-(OH)2D3 had no effect. At an extracellular Ca2+ concentration of less than 500 nmol/l, TRH-induced TSH release was observed only after treatment with 1,25-(OH)2D3 (P<0·01). As the extracellular Ca2+ concentration was increased, greater increments of TRH-induced TSH release were observed following pretreatment with 1,25-(OH)2D3 (P<0·01). However, the effect of 1,25-(OH)2D3 in the thyrotroph was independent of the pretreatment extracellular Ca2+ concentration. We have shown that 1,25-(OH)2D3 acts selectively on the thyrotroph to enhance in-vitro responsiveness to TRH and KCl. These data suggest that the action of 1,25-(OH)2D3 in the thyrotroph is to enhance intracellular signal transduction. They further support a permissive or regulatory role of vitamin D in the normal pituitary gland.
Journal of Endocrinology (1989) 121, 441–450
A peptidase activity from primate liver that inactivates oxytocin in vitro: purification and partial characterization
Authors: Sri Krishna G. , Kanagasabapathy A. S. 
Published: December 2008

ABSTRACT
An aminopeptidase from monkey (Macaca radiata) liver, inactivating oxytocin in vitro and located predominantly in the lysosomal and microsomal fractions, was purified by chromatography on Bio-Gel HTP, DEAE-Sephacel and nickel ion chelate gel and gel filtration on Sephacryl S300. Absence of binding to nickel ion chelate gel indicated the absence of exposed histidine and thiol residues on the enzyme. The enzyme appeared to be a high molecular weight (Mr 106 000) monomeric protein. It was sensitive to inhibition by metal chelators and was found to be a zinc metalloprotein by atomic absorption spectrophotometry. Divalent metal ions Ni2+ and Co2+, and sulphydryl activators glutathione and 2-mercaptoethanol had activating effects, while 4-chloro mercuribenzoate, amino acids with large hydrophobic side chains and l-cystine, β-lactam antibiotic cloxacillin and peptidase inhibitor amastatin had inhibitory effects on the enzyme activity. The enzyme was most active against S-benzyl l-cysteine 4-nitroanilide substrate. The properties of the enzyme were distinct from those of the well-characterized alanine and leucine aminopeptidases (EC 3.4.11.2 and EC 3.4.11.1 respectively) of liver, and of primate placental cystine aminopeptidases (EC 3.4.11.3).
Journal of Endocrinology (1989) 121, 537–544
EFFECT OF THE TFM MUTATION ON HANDEDNESS IN MICE
Authors: Nosten M. , Roubertoux P. , Degrelle H. , Leboyer M. 
Published: December 2008

ABSTRACT
The hyposthesis has been proposed that testosterone is involved in the determination of handedness in man: a high sensitivity to testosterone being associated with left handedness. Handedness in mice is tested according to Collins' paradigm: most mice present either a right or a left paw preference but others are ambilateral. The hypothesis that there is an association between a low neonatal imprinting by testosterone and a strong handedness (right or left) is tested here using Tfm male mice which are testosterone insensitive. Our results confirmed the hypothesis, since Tfm males were as well lateralized as their female siblings and significantly more strongly lateralized than their male siblings not carrying the mutation.
Effects of recombinant human interleukin-1α, -1β, 2 and 6 on ACTH synthesis and release in the mouse pituitary tumour cell line AtT-20
Authors: Fukata J. , Usui T. , Naitoh Y. , Nakai Y. , Imura H. 
Published: December 2008

ABSTRACT
The effects of recombinant human interleukin (rhIL)-1α, -1β, 2 and 6 on the release of ACTH from the ACTH-producing tumour cell line AtT-20 of the mouse were studied during relatively long periods of incubation. Levels of ACTH in the media, measured by radioimmunoassay, were increased by the addition of rhIL-1α or -1β after latent periods of more than 4 h. RhIL-1α and -1β were almost equally potent in this experiment and the minimum, half-maximum and maximum effective concentrations of both rhIL-1α and -1β were about 0·1 pmol/l, 1–3 pmol/l and 10–100 pmol/l respectively. During incubation with rhIL-1β, immunoreactive ACTH levels and mRNA levels of the ACTH precursor pro-opiomelanocortin in cells also increased without apparent changes in the growth rate of the cells. Although the AtT-20 cells used in this study were quite insensitive to human/rat corticotrophin-releasing hormone (CRH), the cells showed a significant response to CRH after incubation with rhIL-1β. RhIL-6 showed similar effects to those of rhIL-1β on ACTH synthesis and release; increasing ACTH in cells and media after a certain latent period. On the other hand, rhIL-2 did not change ACTH levels in the AtT-20 cells in this study. These observations indicate that rhIL-1α, -1β and rhIL-6 have direct effects on ACTH-producing cells to stimulate the release and synthesis of ACTH after a latent period.
Journal of Endocrinology (1989) 122, 33–39
Growth hormone (GH) release after administration of GH-releasing hormone in relation to endogenous 24-h GH secretion in short children
Authors: Gelander L. , Albertsson-Wikland K. 
Published: December 2008

ABSTRACT
Endogenous GH secretion was measured every 20 min for 24 h in 36 short children. This was immediately followed by an i.v. injection of GH-releasing hormone (GHRH)(1–29)-NH2 (1 μg/kg), and GH was estimated every 15 min for the following 2 h. The aim was to determine whether endogenous pulsatile GH secretion had any relation to, or influence on, the GH release induced by GHRH. A high variability was found both in the 24-h GH secretion expressed as area under the curve above the baseline (0–1588 mU/l × 24 h) and the maximal GH response to GHRH (5–296 mU/l), as well as after an arginine–insulin tolerance test (4–59 mU/l). We found a positive correlation (correlation coefficient of Spearman (rs) = 0·49; P < 0·01) between the GH response to GHRH and the spontaneous GH secretion over a 24-h period, in spite of a negative correlation (rs = −0·80; P < 0·01) with the GH secretion during the preceeding 3 h. We conclude that the GH response to a GHRH test correlates with endogenous GH secretion in short children, and may be helpful in estimating the ability to release GH. It is important, however, to be aware of the influence of the spontaneous GH secretion during the 3 h immediately preceeding administration of GHRH.
Journal of Endocrinology (1989) 122, 61–68