bluuebunny/crossref_metadata_2025 huggingface dataset:
Extrapancreatic islets of Langerhans: ontogenesis and alterations in diabetic condition
Authors: Bendayan M , Park I-S
Published: December 2004

The existence of extrapancreatic islets in the duodenal mucosa of the adult rat has been established by morphological studies and the development of these islets has been followed from the early embryonic stage to neonatal and adult life. Like the pancreatic islets, glucagon cells were the first to appear at day 12 of gestation. However, in contrast to the pancreatic islets, insulin was not detected in the extrapancreatic islets until birth. At this stage, the different endocrine cells assume their classical topography, insulin cells being surrounded by non-insulin endocrine cells. In addition, the behaviour of these extrapancreatic islets in diabetic conditions was evaluated on streptozotocin-induced diabetic rats as well as on spontaneous BB Wistar diabetic rats. In both conditions, the extrapancreatic islets were found in the duodenal mucosa but were mainly composed of glucagon cells, the insulin cells having disappeared. These results demonstrate that the extrapancreatic islets are a common normal feature of the rat duodenal mucosa. They appear during fetal development, are present in different strains of rats and behave similarly to the pancreatic islets under spontaneous or chemically induced diabetic conditions. Although their exact role remains to be established, they probably react to local hyperglycaemic environment due to intestinal absorption.

Journal of Endocrinology (1997) 153, 73–80
Release of Type II phospholipase A2 immunoreactivity and phospholipase A2 enzymatic activity from human placenta
Authors: Farrugia W , Rice G E , Wong M H , Scott K F , Brennecke S P
Published: December 2004

The aim of this study was to determine whether Type II phospholipase A2 (PLA2) is released from late pregnant human placental tissue. Placental explants were incubated in vitro and the release of immunoreactive (ir) Type II PLA2 and PLA2 enzymatic activity into the medium was determined. Both irType II PLA2 and PLA2 enzymatic activity accumulated in the incubation medium in a time-dependent manner (P<0·0001). This release was not associated with a loss of cell membrane integrity, as indicated by measurement of the intracellular enzyme, lactate dehydrogenase, in the incubation medium. The concentration of irType II PLA2 and PLA2 enzyme activity present in incubation medium were significantly correlated (P<0·01). Consistent with the hypothesis that Type II PLA2 may be stored in secretory granules within human placental tissue, incubation in the presence of a membrane depolarising concentration of KCl (60 mm) caused the release of irType II PLA2 2·0-fold (P<0·001). PLA2 enzyme activity released into the incubation medium displays biochemical characteristics consistent with those previously reported for secretory PLA2 isozymes, that is, a requirement for millimolar concentrations of calcium for optimal enzyme activity, inhibited by reducing agents, such as dithiothreitol and insensitive to heat inactivation. The data obtained in this study establish that irType II PLA2 is released from term placenta, when incubated in vitro. The release of this extracellularly-active PLA2 isozyme may contribute to gestational and labour-associated increases in glycerophospholipid metabolism and prostaglandin formation.

Journal of Endocrinology (1997) 153, 151–157
Induction of 24-hydroxylase cytochrome P450 mRNA by 1,25-dihydroxyvitamin D and phorbol esters in normal rat kidney (NRK-52E) cells
Authors: Armbrecht H J , Chen M L , Hodam T L , Boltz M A
Published: December 2004

The biologically active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), acts on intestinal, renal, and bone cells to regulate skeletal and mineral metabolism. 1,25(OH)2D also induces 24-hydroxylase activity in these target cells. The 24-hydroxylase hydroxylates 1,25(OH)2D to 1,24,25-trihydroxyvitamin D and 25(OH)D to 24,25-dihydroxyvitamin D. The production of 1,24,25-trihydroxyvitamin D is thought to be the first step in the inactivation of 1,25(OH)2D by its target tissues. Previous studies have characterized the induction of the 24-hydroxylase by 1,25(OH)2D in clonal cell lines from intestine and bone. The purpose of these studies was to characterize the induction of the 24-hydroxylase by 1,25(OH)2D in the kidney, using the clonal rat renal cell line NRK-52E. 1,25(OH)2D (10−7 m) increased the mRNA levels for the cytochrome P450 component of the 24-hydroxylase (P450cc24) by sevenfold after 36 h in NRK-52E cells. 1,25(OH)2D increased P450cc24 mRNA levels in a dose-dependent manner with an EC50 of 10−8 m. In parallel experiments, 1,25(OH)2D significantly increased 24-hydroxylase enzyme activity after 48–72 h. The increase in P450cc24 mRNA induced by 1,25(OH)2D required on-going transcription and translation and was inhibited by H-7, a protein kinase C inhibitor. Tetradecanoyl phorbol acetate markedly increased the magnitude of the tissue responsiveness to 1,25(OH)2D by a protein kinase C-dependent pathway. These studies demonstrate that 1,25(OH)2D increases P450cc24 mRNA levels in NRK-52E cells by a mechanism requiring new protein synthesis and involving protein kinase C. This is in contrast to the action of 1,25(OH)2D in intestinal cells, which does not require new protein synthesis, and in osteoblastic cells, which does not involve protein kinase C.

Journal of Endocrinology (1997) 153, 199–205
Associations between insulin-like growth factor-I (IGF-I), IGF-binding protein-1, insulin and other metabolic measures after controlling for genetic influences: results from middle-aged and elderly monozygotic twins
Authors: Hong Y , Brismar K , Hall K , Pedersen N L , de Faire U
Published: December 2004

It has previously been shown that the serum levels of insulin-like growth factor-I (IGF-I), IGF-binding protein-1 (IGFBP-1), and insulin are influenced by genetic effects to various degrees. From a clinical and preventive point of view, however, it is important to identify potentially modifiable non-genetic factors influencing the levels of these measures. Because monozygotic twin pairs share the same genetic background, differences in phenotypic levels within monozygotic twin pairs are believed to be due to non-genetic influences. Accordingly, the associations between intrapair differences in one phenotype and intrapair differences in another phenotype are also due to non-genetic influences. The present sample of 97 pairs of monozygotic twins from the population-based Swedish Adoption/Twin Study of Aging (SATSA) provided the opportunity to assess non-genetic influences on the levels of IGF-I, IGFBP-1, and insulin. Several metabolic measures were found to account for the variation of IGF-I, IGFBP-1, and insulin after controlling for the genetic influences. IGFBP-1 and glucose were significant predictors for the levels of IGF-I. IGFBP-1 and glucose together explained about one quarter of the non-genetic variation of IGF-I. However, when IGFBP-1 was dropped from the regression model, insulin was the only independent predictor of IGF-I, and explained about 19% of the non-genetic variation for IGF-I. For IGFBP-1, insulin and IGF-I were the significant non-genetic predictors. Insulin and IGF-I explained about 28 and 8% respectively of the non-genetic variation for IGFBP-1, while for insulin, IGF-I, triglycerides, body height, glucose, and body mass index (BMI) explained approximately 20, 12, 6, 5 and 5% respectively of the non-genetic variation.

Journal of Endocrinology (1997) 153, 251–257
Localization of angiotensin II receptor subtypes AT1 and AT2 in the pancreas of rodents
Authors: Leung P S , Chan H C , Fu L X M , Wong P Y D
Published: December 2004

Previous studies have demonstrated the existence of several key components of the renin–angiotensin system in the pancreas. In the present study, the localization of angiotensin II receptor subtypes, type I (AT1) and type II (AT2), in the mouse and the rat pancreas was studied by immunocytochemistry using specific antipeptide antibodies against the second extracellular loops of AT1 and AT2 receptors in conjunction with confocal laser scanning microscopy. In the mouse, immunoreactivity for AT1 and AT2 was observed predominantly in the endothelia of the blood vessels and the epithelia of the pancreatic ductal system. Similar distribution of immunoreactivity for AT1 and AT2 was also observed. However, the intensity of immunoreactivity for AT1 and AT2 was stronger in the rat than that found in the mouse pancreas. Much weaker immunostaining for both AT1 and AT2, as compared with that found in ductal regions, was also found in the acini of the rodent pancreas. Together with the previous findings, the present results suggest that AT1 and/or AT2 receptors may play a role in regulating pancreatic functions in the rodent.

Journal of Endocrinology (1997) 153, 269–274
Trehalose inhibits the release of adipokinetic hormones from the corpus cardiacum in the African migratory locust, Locusta migratoria, at the level of the adipokinetic cells
Authors: Passier P C C M , Vullings H G B , Diederen J H B , Van der Horst D J
Published: December 2004

The effect of trehalose at various concentrations on the release of adipokinetic hormones (AKHs) from the adipokinetic cells in the glandular part of the corpus cardiacum of Locusta migratoria was studied in vitro. Pools of five corpora cardiaca or pools of five glandular parts of corpora cardiaca were incubated in a medium containing different concentrations of trehalose in the absence or presence of AKH-release-inducing agents. It was demonstrated that trehalose inhibits spontaneous release of AKH I in a dose-dependent manner. At a concentration of 80 mm, which is the concentration found in the hemolymph at rest, trehalose significantly decreased the release of AKH I induced by 100 μm locustatachykinin I, 10 μm 3-isobutyl-1-methylxanthine (IBMX) or high potassium concentrations. The specificity of the effect of trehalose was studied by incubating pools of corpora cardiaca with the non-hydrolyzable disaccharide sucrose or with glucose, the degradation product of trehalose, both in the presence and absence of 10 μm IBMX. Sucrose had no effect at all on the release of AKH I, whereas glucose strongly inhibited its release. The results point to the inhibitory effect of trehalose on the release of AKH I being exerted, at least partly, at the level of the adipokinetic cells, possibly after its conversion into glucose. The data presented in this study support the hypothesis that in vivo the relatively high concentration of trehalose (80 mm) at rest strongly inhibits the release of AKHs. At the onset of flight, the demand for energy substrates exceeds the amount of trehalose that can be mobilized from the fat body and consequently the trehalose concentration in the hemolymph decreases. This relieves the inhibitory effect of trehalose on the release of AKHs, which in turn mobilize lipids from the fat body.

Journal of Endocrinology (1997) 153, 299–305
Differential effect of carbamazepine and valproate monotherapy on plasma levels of oestrone sulphate and dehydroepiandrosterone sulphate in male epileptic patients
Authors: Geisler J , Engelsen B A , Berntsen H , Geisler S , Lønning P E
Published: December 2004

Steroid sulphates such as oestrone sulphate (OE1S) and dehydroepiandrosterone sulphate (DHEAS) have been suggested to be of biological importance in different disease states such as breast cancer and atherosclerosis. Previous studies have shown that drugs such as aminoglutethimide and rifampicin that induce P450-dependent mixed-function oxygenases selectively suppress plasma OE1S levels. The aim of this study was to evaluate the influence of treatment with carbamazepine, an antiepileptic drug known to stimulate mixed-function oxygenases, on plasma levels of OE1S and DHEAS. We measured plasma OE1S and DHEAS together with other plasma oestrogens and androgens in male epileptic patients before and during carbamazepine monotherapy. Patients treated with valproate monotherapy acted as a control group. Treatment with carbamazepine decreased plasma OE1S levels from a mean value of 810·8 to 411·6 pmol/l (mean suppression to 50·7% of pretreatment levels, P<0·001). Similarly, the ratio of OE1S to OE1 fell to 59·9% of pretreatment levels (P<0·001). DHEAS decreased from a mean level of 4·9 μmol/l before treatment to 3·0 μmol/l during carbamazepine therapy (mean reduction to 62·7% of pretreatment levels (P<0·001)), while the ratio of DHEAS to DHEA fell to 63·0% of pretreatment values (P<0·01). No significant change in plasma levels of the other oestrogens or androgens measured was observed. Treatment with valproate caused a slight decrease in FSH levels (P<0·05), but no change in any of the other hormones measured was observed. Studies are warranted to evaluate the possible effects of long-term treatment with carbamazepine on the risk of developing endocrine-sensitive tumours and cardiovascular disease and also the possible effects of alterations in plasma DHEAS on epileptic activity.

Journal of Endocrinology (1997) 153, 307–312
Dietary essential fatty acid supplementation, urinary calcium excretion and reproductive performance in the diabetic pregnant rat
Authors: Garland H O , Forshaw A G , Sibley C P
Published: December 2004

Hypercalciuria may be a contributory factor to the disturbed calcium homoeostasis seen in diabetic pregnant rats and their offspring. In diabetes, essential fatty acid metabolism is impaired. We have therefore investigated whether feeding a diet supplemented with essential fatty acids will ameliorate the hypercalciuria of diabetic pregnancy and improve reproductive performance.

Female rats were fed a standard rat diet, a fat-free diet plus evening primrose oil or a fat-free diet plus sunflower oil. They were injected with streptozotocin or vehicle and mated. Urine samples were analysed for calcium before injection and during gestation.

Term-pregnant diabetic rats fed evening primrose oil showed a 73% reduction in urinary calcium output compared with similar rats fed standard diet (P<0·001). The corresponding reduction was 44% in diabetic rats fed sunflower oil (P<0·001). A depletion of essential fatty acids in diabetes may therefore be associated with hypercalciuria; dietary supplementation, particularly with evening primrose oil, appears to correct the problem.

Diabetic pregnant rats fed evening primrose oil showed a significantly greater live fetal mass (85 ± 2 vs 33 ± 12 g; P<0·05) compared with similar rats fed standard diet. Such findings may imply a normalization of placental transport by essential fatty acids. Rats fed evening primrose, but not sunflower oil, also showed a reduced incidence of diabetes after streptozotocin injection compared with rats fed standard diet (63 vs 86%). Rats fed on evening primrose oil that did become diabetic were less hyperglycaemic than those on the standard diet (29 ± 2 vs 37 ± 2 mmol/l), suggesting that the oil may have anti-diabetic properties.

Journal of Endocrinology (1997) 153, 357–363
Effects of hyperprolactinaemia on glucose tolerance and insulin release in male and female rats
Authors: Reis F M , Reis A M , Coimbra C C
Published: December 2004

It has been shown that prolactin (PRL) induces glucose intolerance, hyperinsulinaemia and insulin resistance in several animal species, including rats. However, the sex differences regarding glucose homeostasis and insulin release in hyperprolactinaemic subjects have not been assessed to date. In the present study, hyperprolactinaemic (pituitary-grafted) or control (sham-operated) male and female rats were submitted to an i.v. glucose tolerance test (30 mg/100 g body weight, 30% glucose). Grafted female rats had fasting plasma glucose concentrations 26% above control (P<0·01). After the glucose load there was a rapid and pronounced increase in plasma glucose levels in all animal groups, followed by a return to basal values within 30 min. However, the glucose concentrations in hyperprolactinaemic rats were significantly greater than those in controls at 5 min (males, P<0·05) and 30 min (females, P<0·05). The glucose disappearance rate was significantly increased in the grafted females compared with control (P<0·01) and slightly increased in the grafted males. Plasma insulin concentration increased just after glucose load and returned to basal values within 5 min in all groups except for the grafted females, which had recovered their basal insulin levels at 15 min. The grafted male rats had insulin concentrations higher than those of sham-operated controls at 2 min (28·9 ± 3·6 vs 17·3 ± 2·1 μU/ml, P<0·01), whereas females had plasma insulin concentrations greater than those in sham-operated controls 10 min after the glucose load (15·9 ± 1·9 vs 10·1 ± 1·4 μU/ml, P<0·05). The areas under the plasma insulin concentration–time curves were also significantly increased in the hyperprolactinaemic rats and were positively correlated with plasma PRL concentrations (r=0·613, P<0·01). These results demonstrate that moderate chronic hyperprolactinaemia is associated with increased glucose-induced insulin release, which was altered at different times after the glucose load in grafted male and female rats, whereas fasting hyperglycaemia was observed only in grafted females, indicating a sexual dimorphism in the diabetogenic effects of PRL in rats.

Journal of Endocrinology (1997) 153, 423–428
Involvement of bombesin in spermine-induced corticosterone secretion and intestinal maturation in suckling rats
Authors: Kaouass M , Deloyer P , Dandrifosse G
Published: December 2004

In this study we investigated whether brain-gut peptides are implicated in the activation of the hypophysial-adrenal axis (HAA) in suckling rats treated orally with spermine.

The first group of rats received i.p. injections of bombesin, vasoactive intestinal polypeptide (VIP), somatostatin or neurotensin, starting on day 11 of life, and killed on day 14. The small intestine was removed and analysed for its content of proteins, DNA, polyamines and for its specific activity (SA) of disaccharidases. The second group of rats received one of the hormones cited above and was killed 45 min after the treatment for determination of corticosterone plasma concentration. Rats of the third group were adrenalectomised then treated with bombesin as the first group. The fourth group of rats was orally treated with spermine and sacrificed 2, 3, 4, 6 and 8 h thereafter for analysis of plasma and intestinal concentrations of bombesin.

The i.p. injection of bombesin increased the sucrase and maltase SA in the whole small intestine, while it decreased the lactase SA in the distal part. Intestinal weight and length, contents of DNA, protein, spermidine and spermine, and corticosterone plasma levels were enhanced by bombesin treatment. Somatostatin, neurotensin and VIP were ineffective on all the parameters studied. Adrenalectomy, in bombesin-treated rats, decreased the sucrase and maltase SA in the whole intestine, and decreased the lactase SA in the proximal intestine. It had no effect on intestinal weight and length, and protein content. Oral administration of spermine had no effect on plasma concentration of bombesin, whereas it decreased the content of this peptide in the whole small intestine.

It is possible that bombesin may control intestinal development in suckling rats and be a link between the ingestion of spermine and the liberation of corticosterone by the adrenal glands.

Journal of Endocrinology (1997) 153, 429–436
Participation of JAK, STAT and unknown proteins in human placental lactogen-induced signaling: a unique signaling pathway different from prolactin and growth hormone
Authors: Takeda Takashi , Kurachi Hirohisa , Yamamoto Toshiya , Homma Hiroaki , Morishige Kenichirou , Miyake Akira , Murata Yuji
Published: December 2004

The signal transduction mechanism involved in human placental lactogen (hPL) was studied. We have identified that hPL rapidly stimulated the tyrosine phosphorylation of at least 7 proteins including Janus Kinases (JAK1 and JAK2) and a signal transducer and activator of transcription protein (Stat3). This is the first evidence that the JAK-STAT pathway is involved in the hPL signaling. Moreover, two unknown proteins which were different from STAT proteins (Stat1, 3 and 5) in sizes were predominantly tyrosine-phosphorylated. Because human growth hormone (hGH) activates Stat1, 3, 5 and human prolactin (hPRL) activates Stat5, these results show that hPL uses a unique signal transduction pathway which is different from hGH and hPRL.
Cerebellin and cerebellin mRNA in the human brain, adrenal glands and the tumour tissues of adrenal tumour, ganglioneuroblastoma and neuroblastoma
Authors: Satoh F , Takahashi K , Murakami O , Totsune K , Ohneda M , Mizuno Y , Sone M , Miura Y , Takase S , Hayashi Y , Sasano H , Mouri T
Published: December 2004

The expression of cerebellin and cerebellin mRNA was studied by radioimmunoassay and Northern blot analysis in the human brain, adrenal gland and the tumour tissues of adrenal tumour, ganglioneuroblastoma and neuroblastoma. Immunoreactive cerebellin was detected in every region of brain studied, with the highest concentrations found in the hemisphere of the cerebellum (424·2 ± 12·6 pmol/g wet weight, n=6, mean ± s.e.m.) and the vermis of the cerebellum (256·8 ± 30·5 pmol/g wet weight). Immuno-reactive cerebellin was also detected in the pituitary (8·2 ± 1·8 pmol/g wet weight), the spinal cord (3·3 ± 0·3 pmol/g wet weight) and the normal parts of adrenal glands (2·98 ± 0·37 pmol/g wet weight, n=9) and some tumour tissues, such as phaeochromocytomas, cortisol-producing adrenocortical adenomas, ganglioneuroblastomas and neuroblastomas. Northern blot analysis showed that cerebellin mRNA was highly expressed in the hemisphere and vermis of the cerebellum. Cerebellin mRNA was also expressed in other regions of the brain and the tumour tissues of phaeochromocytoma, cortisol-producing adrenocortical adenoma, ganglioneuroblastoma and neuroblastoma. Immunocytochemistry of the normal adrenal gland showed that immunoreactive cerebellin was localized in the adrenal medulla. The present study has shown the expression of cerebellin and cerebellin mRNA, not only in the cerebellum but also in other regions of the brain and some tumours, such as cortisol-producing adrenocortical adenoma, phaeochromocytoma and neuroblastoma. These findings suggest possible pathophysiological roles of cerebellin peptides, not only in the cerebellum, but also in the extra-cerebellar tissues.

Journal of Endocrinology (1997) 154, 27–34
Thyroid hormone, vitamin D and retinoid receptor expression and signalling in primary cultures of rat osteoblastic and immortalised osteosarcoma cells
Authors: Bland R , Sammons R L , Sheppard M C , Williams G R
Published: December 2004

3,5,3′-Tri-iodothyronine (T3), 1α,25(OH)2-vitamin D3 (D3) and retinoids activate related nuclear receptors which interact by heterodimerisation to regulate gene expression. Actions of each hormone are discrete and may be specified by changes in the relative concentrations of their receptors (T3R, vitamin D receptor (VDR), retinoic acid receptor (RAR), retinoid X receptor (RXR)). T3, D3 and retinoids are essential for skeletal development and maintenance and we have previously shown complex interactions amongst their signalling pathways in osteosarcoma cells. In these studies we demonstrate that similar T3R, VDR, RAR and RXR proteins are co-expressed in both osteoblast lineage cell primary cultures and osteosarcoma cells by Western blotting. We investigated whether hormone interactions in bone result from changes in receptor stoichiometry. Cells were treated with combinations of T3, D3, 9-cis retinoic acid (9-cis RA) and all-trans retinoic acid (RA) that are known from previous studies to produce complex cell specific responses. No alteration in expression of any receptor protein was seen in response to any hormone combination in three phenotypically distinct osteosarcoma cell lines. Thus, in contrast to studies of overexpressed receptors in vitro, changes in the physiological concentrations of endogenous T3R, VDR, RAR and RXR do not specify discrete hormone actions in osteoblastic cells. Other unidentified factors are likely to modulate hormone action in these bone cells.

Journal of Endocrinology (1997) 154, 63–74
Oestrogen and progesterone control basic fibroblast growth factor mRNA in the rat uterus
Authors: Rider V , Carlone D L , Foster R T
Published: December 2004

Cell proliferation and differentiation in the rodent uterus are probably controlled by the interaction of female sex steroids with polypeptide growth factors. Uterine basic fibroblast growth factor (bFGF) mRNA was measured by RNase protection during the time (days 2–4) of endometrial cell proliferation in the pregnant rat. bFGF transcripts were detected at each of the 3 days of pregnancy examined. To investigate the influence of oestrogen and progesterone on bFGF mRNA accumulation, ovariectomized rats were treated with oestradiol for 48 h followed by a single injection of oestradiol, progesterone, the two steroids co-injected or oil vehicle alone. Uterine RNA was collected 6 h after the last hormone injection. Steroid treatments increased steady-state uterine bFGF mRNA compared with vehicle control animals as measured by RNase protection. Northern blot analysis of c-fos and c-jun mRNAs from these same treatment groups revealed increased protooncogene expression in the uterus of hormone treated rats compared with the control animals. Temporal analysis of bFGF mRNA in ovariectomized rats at 1, 3 and 6 h after acute oestrogen and oestrogen-progesterone co-administration showed a dual pattern of transcript accumulation. Both hormone treatments increased bFGF mRNA within 1 h compared with vehicle injected rats. Co-administration of the two hormones, however, repressed bFGF mRNA accumulation relative to oestrogen at 3 and 6 h. Together, these studies provide evidence that bFGF control of uterine cell proliferation in pregnant rats can occur from newly synthesized bFGF. Moreover, the results suggest that progesterone is a potent stimulator of bFGF expression in the uterus.

Journal of Endocrinology (1997) 154, 75–84
High levels of fetal membrane activin βA and activin receptor IIB mRNAs and augmented concentration of amniotic fluid activin A in women in term or preterm labor
Authors: Petraglia F , Di Blasio A M , Florio P , Gallo R , Genazzani A R , Woodruff T K , Vale W
Published: December 2004

The aim of the present study was to evaluate whether spontaneous labor at term and pathological preterm labor are associated with changes in the expression of activin A and activin receptor mRNAs in fetal membranes. In addition, amniotic fluid activin A concentration in women delivering at term or undergoing preterm labor was also measured.

The expression of activin βA subunit and activin receptor type II and type IIB mRNAs was assessed by reverse transcriptase-PCR on specimens of amnion and chorion collected from patients delivering at term or undergoing preterm labor. Control specimens were collected from women delivered by elective cesarean section who had not experienced labor.

A specific two-site ELISA was used to measure activin A concentrations in the amniotic fluid. A cross-sectional study of amniotic fluid retrieved by amniocentesis from 109 pregnant women was carried out. Patients were classified into the following groups: (1) healthy controls at term but not in labor (n=25); (2) healthy controls at term in spontaneous labor (n=40); (3) healthy controls between 23 and 36 weeks of gestation (n=12); (4) patients in preterm labor responding to tocolytic treatment (n=19); (5) patients in preterm labor with subsequent delivery (n=13).

Activin βA subunit and activin receptor type IIB mRNA levels in both the chorion and amnion in women delivering at term or after preterm labor were significantly higher than in women delivering without undergoing labor (P<0·01). Expression of activin receptor type II mRNA in membranes did not differ among the three groups of women. Amniotic fluid activin A concentration in patients in labor was significantly higher than in those at term but not in labor (P<0·01). Patients in preterm labor had significantly higher amniotic fluid activin A concentrations than women at the same stage of gestation (P<0·01). The highest values were found in women undergoing preterm labor and subsequent delivery.

In conclusion, spontaneous labor and preterm labor are characterized by increased synthesis and release of activin A from amniotic and chorionic cells and by an augmented expression of activin type IIB receptor.

Journal of Endocrinology (1997) 154, 95–101
The expression of parathyroid hormone-related protein mRNA and immunoreactive protein in human amnion and choriodecidua is increased at term compared with preterm gestation
Authors: Curtis N E , Ho P W M , King R G , Farrugia W , Moses E K , Gillespie M T , Moseley J M , Rice G E , Wlodek M E
Published: December 2004

Parathyroid hormone-related protein (PTHrP) gene expression and/or immunoreactive protein have previously been identified in the uterus and intrauterine gestational tissues. The putative roles of PTHrP during pregnancy include vasodilatation, regulation of placental calcium transfer, uterine smooth muscle relaxation and normal fetal development. The aims of this study were 1) to determine the tissue-specific and temporal expression of PTHrP mRNA and immunoreactive protein in human gestational tissues collected at preterm and term; and 2) to determine the effect of labour on PTHrP expression by collecting these tissues from women undergoing elective caesarean section (before labour), intra-partum caesarean section during spontaneous-onset labour (during labour), and women with spontaneous labour and normal vaginal delivery (after labour). Total RNA and protein were extracted from placenta, amnion (over placenta and reflected) and choriodecidua for analysis by Northern blot (using a specific human PTHrP cDNA probe), and by N-terminal PTHrP RIA respectively. In amnion over placenta, reflected amnion and choriodecidua both PTHrP mRNA relative abundance and immunoreactive protein were significantly elevated at term compared with preterm (P<0·01). At term, both PTHrP and its mRNA were significantly greater in amnion than in placenta and choriodecidua (P<0·05). Also, both PTHrP and its mRNA were significantly elevated in amnion over placenta compared with reflected amnion (P<0·05). The expression of PTHrP and its mRNA did not change in association with term labour or rupture of the fetal membranes, therefore this study provides no evidence for a specific PTHrP role in the onset and/or maintenance of term labour. However, the significant up-regulation of PTHrP mRNA and protein in the fetal membranes at term compared with preterm suggests an important role in late human pregnancy.

Journal of Endocrinology (1997) 154, 103–112
Characterization of the AT1 angiotensin II receptor expressed in guinea pig liver
Authors: García-Sáinz J A , Martínez-Alfaro M , Romero-Avila M T , González-Espinosa C
Published: December 2004

In guinea pig hepatocytes angiotensin II induced phosphorylase a activation. This effect was mimicked by other angiotensins with the potency order: angiotensin II (EC50 ≈1 nm)>angiotensin III (EC50 ≈30 nm)>angiotensin I (EC50 ≈300 nm). The effect of 10 nm angiotensin II was blocked by the angiotensin II receptor AT1-selective antagonists irbesartan and losartan (Ki values of ≈1 nm and ≈10 nm for irbesartan and losartan respectively) but not by the AT2-selective antagonist PD123177.

Similar data were obtained when the production of [3H]IP3 from [3H]myo-inositol-labeled cells was studied. Angiotensin II induced a dose-dependent increase in [3H]IP3 production; the maximal effect (≈3-fold) was observed at a concentration of 10 μm. This effect of angiotensin II was completely blocked by the AT1-selective antagonists irbesartan and losartan, but only in a very limited fashion by PD123177. [125I][Sar1-Ile8]angiotensin II bound with high affinity (≈3·8 nm) to a moderately abundant number of sites (≈660 fmol/mg protein) in guinea pig liver membranes. Binding competition experiments indicate the following orders of potency for agonists: angiotensin II (≈1·5 nm)>angiotensin III (≈7 nm)>angiotensin I (≈176 nm), and for antagonists: irbesartan (≈0·5 nm)>losartan (≈36 nm)>> PD123177 (>> 10 000 nm).

The functional and binding data strongly indicate that the effects of angiotensin II were mediated through AT1 receptors. Expression of the mRNA for these receptors was confirmed by RT-PCR and hybridization of the reaction product with a radiolabeled rat AT1 receptor cDNA probe.

Journal of Endocrinology (1997) 154, 133–138
The role of protein kinase C in GH secretion induced by GH-releasing factor and GH-releasing peptides in cultured ovine somatotrophs
Authors: Wu D , Clarke I J , Chen C
Published: December 2004

The involvement of protein kinase C (PKC) in the action of GH-releasing factor (GRF) and synthetic GH-releasing peptides (GHRP-2 and GHRP-6) was investigated in ovine somatotrophs in primary culture. In partially purified sheep somatotrophs, GRF and GHRP-2 caused translocation of PKC activity from the cytosol to the cell membranes and caused GH release in a dose- and time-dependent manner. GHRP-6 did not cause PKC translocation. The PKC inhibitors, calphostin C, staurosporine and chelerythrine, partially reduced GH release in response to GRF and GHRP-2 at doses which selectively inhibit PKC activity. These inhibitors totally abolished GH release caused by phorbol 12-myristate 13-acetate (PMA). Down-regulation of PKC by the treatment of cells with phorbol 12,13-dibutyrate for 16 h caused a significant (P<0·001) reduction in total PKC activity and totally abolished PKC translocation in response to a challenge with GRF, GHRP-2 or PMA. In addition, down-regulation abolished GH release in response to GRF, GHRP-2 or GHRP-6. Treatment of cells with H89, a selective PKA inhibitor, totally blocked GH release caused by either GRF or GHRP-2 and partially reduced PMA-induced GH release. H89 had no effect on PKC translocation caused by GRF, GHRP-2 or PMA and did not affect GH release caused by GHRP-6. These data suggest that GHRP-2 and GRF activate PKC in addition to stimulating adenylyl cyclase activity. Although the cAMP–protein kinase A (PKA) pathway is the major signalling pathway employed by GRF and GHRP-2, the activation of PKC may potentiate signalling via the cAMP–PKA pathway in ovine GH secretion. Importantly, the effect of PMA in increasing the secretion of GH from ovine somatotrophs is effected, in part, by up-regulation of the cAMP–PKA pathway. We conclude that there is cross-talk between the PKC pathway and the cAMP–PKA pathway in ovine somatotrophs during the action of GRF or GHRP.

Journal of Endocrinology (1997) 154, 219–230
The calcium-sensing receptor: insights into extracellular calcium homeostasis in health and disease
Authors: Pearce SH , Thakker RV
Published: December 2004

The cloning of the BoPCaR1 gene has helped to elucidate many aspects of normal extracellular calcium homeostasis, particularly as applied to the regulation of PTH secretion, calcitonin secretion and renal calcium reabsorption. In addition, loss and gain of function mutations have been found to cause the clinical syndromes of FBH, NSHPT and ADHH respectively. The CaR has also been implicated in the mechanisms leading to primary and uraemic hyperparathyroidism, and autoimmune parathyroid destruction. The recent demonstration that the CaR regulates non-selective cation channel function in rat hippocampal neurones suggests that it may also have a role within the central nervous system that is entirely unrelated to calcium homeostasis (Ye et al. 1996). Finally, the prospect of CaR agonists and antagonists, which may allow PTH secretion to be regulated independently of the serum calcium concentration, also holds much promise for the medical treatment of hyperparathyroidism, renal osteodystrophy and osteoporosis.
Expression of the genes for 3 beta-hydroxysteroid dehydrogenase type 1 and cytochrome P450scc during syncytium formation by human placental cytotrophoblast cells in culture and the regulation by progesterone and estradiol
Authors: Beaudoin C , Blomquist CH , Bonenfant M , Tremblay Y
Published: December 2004

We have investigated the expression of cholesterol side-chain cleavage cytochrome P450 (P450scc) and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) type 1 genes during human trophoblast differentiation in culture and the modulation of their steady-state mRNA levels by steroids. During the first 24 to 48 h after plating, mononucleated cells aggregated, forming colonies. After 60 h in culture, cell diameters were increased and nuclei appeared centrally distributed within large cells, consistent with syncytiotrophoblast formation. During these striking morphological changes in culture the expression and activity levels of 3 beta-HSD type 1 and P450scc increased significantly as isolated cytotrophoblasts progressed to a differentiated state, with P450scc and 3 beta-HSD type 1 mRNAs activities being more abundant in cells cultured for 48 to 72 h. In the same culture, however, the amount of 3 beta-HSD protein decreased during the first 12 to 24 h by 50% compared with freshly isolated trophoblasts but remained at these levels throughout the culture period. The specific activity of the 3 beta-HSD as determined with pregnenolone or dehydroepiandrosterone was similar but increased with time as syncytiotrophoblast was formed in vitro. These observations provide additional evidence that the expression of these two progesterone-synthesizing enzymes is coincident and that they reach their maximum steady-state mRNA levels at a time when syncytium formation occurs in vitro. Incubation of trophoblast cells with progesterone or estradiol increased the abundance of P450scc and 3 beta-HSD type 1 mRNAs but had no significant effect on the amount of 3 beta-HSD protein. These observations of the regulation of 3 beta-HSD type 1 mRNA levels by steroids suggest a complex relationship of the mechanisms regulating transcription/mRNA processing and transduction of the 3 beta-HSD type 1 gene.
Role of cortisol in the ACTH-induced suppression of testicular steroidogenesis in guinea pigs
Authors: Fenske M
Published: December 2004

In order to investigate the role of cortisol in the regulation of testicular function, adult male guinea pigs were challenged with ACTH (20 IU), cortisol (8 or 16 mumol), or with ACTH plus dexamethasone (DEX, 2 mumol). The amounts of cortisol, testosterone, progesterone, and androstenedione present in the plasma or secreted by incubated adrenals or testes were determined by radioimmunoassay. The plasma concentrations of LH were determined using a radioimmunoassay for rat LH. ACTH treatment elevated cortisol plasma concentrations to 999% of control values, whereas it reduced testosterone plasma levels to 43% of control values. ACTH treatment did not affect LH plasma levels. A significant negative correlation was found in ACTH-treated animals, when the cortisol and testosterone plasma concentrations in serially taken blood samples (30-240 min after treatment) were compared (rs = -0.90 and rs = -0.99, P < 0.05). In addition to cortisol, ACTH raised progesterone and androstenedione plasma concentrations. If animals were treated with 2 mumol DEX + ACTH, the plasma levels of cortisol and androstenedione but not of progesterone, testosterone or LH were changed. ACTH stimulated the in vitro secretion of cortisol, progesterone and androstenedione by the adrenals but reduced the in vitro release of androstenedione and testosterone by the testes. In summary, treatment of guinea pigs resulted in elevated cortisol and in reduced testosterone plasma concentrations. The mechanism of the cortisol-induced inhibition of testicular function was independent of the LH plasma concentrations. The in vitro experiments indicate that cortisol directly interacts with the Leydig cells, presumably by inhibiting the activity of the testicular 17 alpha-hydroxylase and/or C17,20-lyase. Taking into account the results of comparable investigations in the rat, the inhibition of the testicular 17 alpha-hydroxylase and/or C17,20-lyase takes place if the intracellular cortisol exceeds the capacity of the 11 beta-hydroxysteroid dehydrogenase to inactivate it.
Post-translational processing of human procorticotrophin-releasing factor in transfected mouse neuroblastoma and Chinese hamster ovary cell lines
Authors: Brar B , Sanderson T , Wang N , Lowry PJ
Published: December 2004

The mouse neuroblastoma cell line (Neuro 2 A) has been shown to contain the mRNA of a prohormone converting enzyme, PC2. The Chinese hamster ovary cell line (CHO) does not express PC2 mRNA, but is thought to contain the ubiquitous protease, furin. The enzyme(s) responsible for releasing corticotrophin-releasing hormone (CRH) from its precursor (proCRH) have not been identified, therefore to investigate the possible function(s) of PC2 or furin in the processing of proCRH, stable Neuro 2 A and CHO cell lines that express the 21 kDa human (h)proCRH were established. A specific two-site IRMA for CRH demonstrated that the hpreproCRH-expressing Neuro 2 A cell line cleaved the CRH precursor to the CRH peptide, and was able to release the mature peptide into cell medium at levels that were 4-fold higher than produced by the hproCRH-expressing CHO cells. RIA showed that the CHO cells secreted levels of CRH-containing peptides that were 10-fold higher than produced by the Neuro 2 A cells. Medium from the transfected CHO and Neuro 2 A cells was analysed by HPLC; this showed that CHO cells released a single protein corresponding to the unprocessed CRH precursor, whereas Neuro 2 A cells secreted two peptides, which could be identified as the 5 kDa CRH(1-41) and residual 16 kDa CRH peptides. These results suggest that Neuro 2 A cells, which contain PC2, can process proCRH to the mature peptide.
Effect of heparin on oestradiol-induced cell growth and proliferation in the uterus of ovariectomized rats
Authors: Gunin AG
Published: December 2004

The aim of this study was to examine the role of heparin in the realization of oestradiol (OE2) effects in the uterus. Ovariectomized rats were treated with a single injection of OE2 dipropionate (10 micrograms/rat, i.m.) along with injections of heparin (in doses of 0.4 mg/rat, i.m.). OE2 effects in the uterus were determined by measuring mitotic indices, proliferating cell nuclear antigen (PCNA)-labelling indices, DNA content, and volumes of cells, nuclei and nucleoli in luminal and glandular epithelia and stromal cells of the endometrium 24, 36 and 48 h after the injection of OE2. Heparin treatment inhibited the OE2-stimulated increase in mitotic activity and DNA content of the uterine structures, whereas OE2-induced increases in cell, nucleus and nucleolus volumes in all uterine structures tested at all the times were greatly augmented by heparin. The OE2-induced increase in PCNA-labelling index in all the cell types had a tendency to increase as the result of heparin action. In the absence of OE2, heparin had no effect on any of the uterine parameters. The effect of heparin is probably realized via changes in the mechanism of oestrogen action in the uterus. Heparin probably prevents passage of the cells from the G1- to the S-phase of the cell cycle and prolongation of the G1-phase with consequent accumulation of the cells in this phase of the cell cycle. This probably leads to reduction of mitotic activity. Furthermore, cells in G1-phase probably prolong their biosynthetic processes causing enlargement of the cell, nucleus and nucleolus volumes.
Phosphoserine/threonine phosphatases in the rat adrenal cortex: a role in the control of steroidogenesis?
Authors: Sayed SB , Whitehouse BJ , Jones PM
Published: December 2004

The involvement of protein kinases in the signal transduction pathways controlling adrenal steroidogenesis is well established, and the phosphorylation of substrates by cAMP-dependent protein kinase is a major mechanism in ACTH action. However, the possibility that protein phosphatases (PPs) might also be involved in this process has not been investigated. The aim of this study was, therefore, to measure the function, expression and enzymic activity of PPs in zona glomerulosa (ZG) and zona fasciculata/reticularis (ZFR) tissue from the rat adrenal cortex. Immunoblot analysis using specific antisera demonstrated the presence in whole adrenals and capsules of PP type 1 (PP1) migrating with an apparent molecular mass of 37 kDa, and PP type 2A (PP2A) migrating with apparent molecular masses of 38 and 31 kDa. The PP inhibitors, okadaic acid (OA), calyculin A (CA), tautomycin and microcystin RR, caused a reduction in PP activity in vitro, at doses between 1 nM and 1 microM. In addition, treatment of ZG cells with the adenylate cyclase stimulator, forskolin (10 microM) resulted in a significant reduction in PP activity. The effects of CA and OA on steroid secretion by ZG and ZFR cells were also investigated. Neither CA nor OA had any effect on basal steroid secretion or on yields of steroid obtained from 22R-hydroxycholesterol at doses between 1 and 100 nM. However, both OA and CA (10 and 100 nM respectively) significantly reduced ACTH-stimulated aldosterone and corticosterone production by ZG and ZFR cells. CA and OA (10 and 100 nM respectively) also reduced steroid secretion by cells stimulated by forskolin (10 microM) or dibutyryl cAMP (200 microM). These results suggest that PPs may be involved in the intracellular mechanisms through which adrenocortical steroidogenesis is regulated, acting at a point after cAMP generation and action, but proximal to the side-chain cleavage of cholesterol.
Impact of antihypertensive therapy on the skeleton: effects of moexipril and hydrochlorothiazide on osteopenia in spontaneously hypertensive ovariectomized rats
Authors: Ma YF , Stimpel M , Liang H , Pun S , Jee WS
Published: December 2004

Skeletal effects of moexipril, an angiotensin-converting enzyme (ACE) inhibitor, and hydrochlorothiazide (HCTZ), a thiazide diuretic, were studied in ovariectomized (OVX) spontaneously hypertensive rats (SHR). Moexipril (10 mg/kg per day), HCTZ (10 mg/kg per day), alone or in combination, as well as 17 alpha-estradiol (30 micrograms/kg per day) were given to OVX SHR immediately after surgery and studied for short- and long-term effects (14 and 56 days respectively). All drugs were given orally. Histomorphometric data on the secondary spongiosa of proximal tibial metaphyses (cancellous bone) and tibiofibular junctions of tibial shafts (cortical bone) were analyzed. Ovariectomy induced cancellous bone loss in SHR by inducing negative bone balance. Estrogen prevented ovariectomy-induced cancellous bone loss in the SHR by reducing bone turnover and partially suppressing the coupling of bone formation to resorption on the endocortical surface. HCTZ reduced blood pressure after 1 week of treatment, yet this effect was no lower than that seen in controls after 3 weeks of treatment. Two weeks of HCTZ transiently prevented ovariectomy-induced increases in bone turnover rate and eroded surface. This delayed ovariectomy induced trabecular bone loss in the proximal tibial metaphysis, but had no effect on the tibial shaft. Like HCTZ, moexipril also reduced blood pressure after the first week of treatment but it had no apparent effect on either the proximal tibial metaphysis or the tibial shaft. A combination of moexipril and HCTZ exhibited a much more potent hypotensive effect and had the same effect on bone mass and dynamic end-points as HCTZ alone. Our data indicate that (1) HCTZ treatment has some transient beneficial effects on both antihypertension and osteoprotection in hypertensive osteopenic rats, (2) the combination of moexipril with HCTZ improved the antihypertensive effect but did not potentiate or hamper the osteoprotective effect of HCTZ, and (3) the skeletal effect of estrogen is not impacted by the hypertensive state. These findings are relevant for the use of ACE inhibitor and thiazide diuretics, alone or in combination, in antihypertensive therapy in postmenopausal women.