bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of fetal hypophysectomy with or without ACTH replacement on the molecular weight profile of enkephalin-containing peptides in the adrenal medulla of the fetal sheep
Authors: Coulter C. L. , Young I. R. , Browne C. A. , McMillen I. C. 
Published: December 2008

ABSTRACT
We have investigated the possible role of the fetal pituitary and ACTH in the control of the synthesis and post-translational processing of the enkephalin precursor, proenkephalin A (proEnk A), in the fetal sheep adrenal gland in late gestation.
Fetal hypophysectomy (n = 8) or sham operations (n = 4) were performed between 109 and 118 days of gestation. At 138–139 days, either ACTH(1–24) (10·5 μg/0·24 ml saline per h, n = 4) was infused intravenously for 72 h into hypophysectomized fetal sheep or 0·9% (w/v) NaCl alone (0·24 ml/h, n = 4) was infused for 72 h into hypophysectomized fetal sheep and sham-operated animals. At the end of the infusion the pregnant ewe was killed and left or right adrenal glands (n = 12) were collected from the fetal sheep that were intact and given saline (Intact + sal; n = 4), hypophysectomized and given saline (Hx + sal; n = 4) and hypophysectomized and given ACTH (Hx + ACTH; n = 4). Each adrenal was homogenized in acid (acetic acid (1 mol/l)/HCl (20 mmol/l)/2-mercaptoethanol (0·2%)). After centrifugation, the supernatant was loaded onto a Sephadex G-75 column (2·0 × 50 cm), eluted at 80 ml/24 h and fractions were collected (5 ml, n = 42). An aliquot of each fraction (2 ml) was dried down prior to enzymatic digestion (trypsin/carboxypeptidase B) and oxidation with H2O2, and assay for methionine-O-enkephalin (immunoreactive Met-O-Enk).
The total adrenal content of immunoreactive Met-O-Enk was significantly greater in the Hx + ACTH group (326·2 ±66·7 (s.e.m.)ng/adrenal) when compared with either the Intact + sal group (152·7 ±44·0 ng/adrenal) or the Hx + sal group (112·1 ±20·8 ng/adrenal). In the adrenal glands from all fetuses immunoreactive Met-O-Enk was found in four molecular weight ranges: < 12 kDa, 12–7 kDa, 7–3 kDa and < 3 kDa. There was no significant difference between the Hx + sal and Hx + ACTH groups in the proportion of immunoreactive Met-O-Enk present in each of the molecular weight ranges in the adrenals and therefore the data from these groups were combined for further statistical analysis. The proportion of immunoreactive Met-O-Enk in the > 12 kDa range was significantly less in the Intact + sal group (5·5 ±2·3%) when compared with the hypophysectomized sheep with or without ACTH replacement (18·7 ± 4·5%).
These data demonstrate that fetal hypophysectomy alters the molecular weight profile of Enk-containing peptides in the adrenal of the fetal sheep and whilst ACTH replacement in the hypophysectomized fetus does not alter the post-translational processing of the Enk-containing peptides, it stimulates an increase in the total amount of immunoreactive Met-O-Enk in the fetal adrenal in late gestation.
Journal of Endocrinology (1992) 134, 369–375
ELEVATING MATERNAL INSULIN-LIKE GROWTH FACTOR-I IN MICE AND RATS ALTERS THE PATTERN OF FETAL GROWTH BY REMOVING MATERNAL CONSTRAINT
Authors: Gluckman P.D. , Morel P.C.H. , Ambler G.R. , Breier B.H. , Blair H.T. , McCutcheon S.N. 
Published: December 2008

ABSTRACT
Fetal growth is normally constrained by maternal factors. This constraint is demonstrated by the usual inverse linear relationship between litter size and mean fetal weight. Cross-breeding experiments between mice of lines selected for high or low plasma insulin-like growth factor (IGF-I) levels suggested that elevations in maternal IGF-I abolish (P <0.01) this constraining effect and reverse the usual positive relationship between fetal and placental size in late gestation. This was confirmed by treating mice and rats throughout pregnancy with IGF-I. In normal mice and in low IGF-I line mice treatment with IGF-I 10μg 8-hourly s.c. from day 1 to 19 of pregnancy) abolished maternal constraint whereas 0.9% (w/v) NaCl treatment did not. In Wistar rats osmotic pumps were implanted to deliver IGF-I (1μg/g body weight per day), bovine GH (bGH; 0.6μg/g body weight per day) or saline from day 1 to 19 of pregnancy. IGF-I therapy but not bGH or saline abolished (P < 0.01) maternal constraint and altered (P <0.01) the relationship between placental and fetal weight.
When high or low IGF-I line mice embryos were transplanted into a normal line of mice, the expected negative relationship (P <0.05) between mean fetal weight and litter size was maintained. However the embryos of the high line were heavier (P <0.05) than those from the low line irrespective of fetal number, suggesting a direct role for IGF-I in the regulation of fetal growth.
Thus both endogenous and exogenous elevations in maternal IGF-I indirectly promote fetal growth either by altering nutrient delivery to the placenta or by affecting placental function.
Interaction between myometrial relaxants and oxytocin: a comparison between relaxin, cromakalim and salbutamol
Authors: Downing S. J. , Hollingsworth M. 
Published: December 2008

ABSTRACT
The influence of treatment with oestradiol on the effects of the uterine relaxants, relaxin, salbutamol (an agonist at β2-adrenoceptors) and cromakalim (a potassium channel opener) and their interactions with the uterine stimulant oxytocin were investigated in vivo in the ovariectomized rat. Oestradiol benzoate (0·4 μg/kg per day) significantly increased sensitivity to cromakalim as an inhibitor of spontaneous uterine contractions compared with vehicle-treated rats by approximately threefold. The same dose of oestradiol benzoate had no effect on uterine sensitivity to salbutamol. Previous studies have shown that this dose of oestradiol benzoate produces a twofold increase in uterine sensitivity to relaxin as an inhibitor of spontaneous contractions. Oestradiol influenced the ability of relaxin to inhibit oxytocin-stimulated uterine contractions. In corn oil-treated rats, uterine responses to relaxin were markedly reduced during oxytocin infusion compared with responses to relaxin before oxytocin; the maximum obtainable response to relaxin was less than 50% inhibition. In oestradiol-treated rats, uterine sensitivity to relaxin during oxytocin infusion was similar to that observed against spontaneous contractions. Cromakalim was able to inhibit uterine contractions during oxytocin infusion in both corn oil- and oestradiol-treated rats, uterine sensitivity to cromakalim being similar in the absence and presence of oxytocin for both hormone treatment groups. Salbutamol was also able to inhibit uterine contractions during oxytocin infusion in both corn oil- and oestradiol-treated rats. Oestradiol treatment increased the potency of salbutamol as an inhibitor of oxytocin-stimulated uterine contractions compared with corn oil treatment by 3·5-fold. The interaction of oestradiol and relaxin during late pregnancy may be important for attenuation of the myometrial response to stimulants.
Journal of Endocrinology (1992) 135, 29–36
Activation of the hypothalamo-pituitary-adrenocortical axis in the conscious rabbit by the pyrogen polyinosinic: polycytidylic acid is dependent on corticotrophin-releasing factor-41
Authors: Milton N. G. N. , Hillhouse E. W. , Milton A. S. 
Published: December 2008

ABSTRACT
The pyrogenic interferon inducer polyinosinic: polycytidylic acid (Poly I: C) was shown to activate the rabbit hypothalamo-pituitary-adrenocortical (HPA) axis in vivo. The immunoreactive cortisol response to Poly I:C (2·5 μg/kg) was shown to have a corticotrophin-releasing factor-41 (CRF-41)-dependent component which was abolished by peripheral immunoneutralization using an anti-CRF41 monoclonal antibody (KCHMB001; 2·5 mg/kg i.v.). Peripheral administration of the arginine vasopressin (AVP) V1 receptor antagonist ([deaminoPen1, O-Me-Tyr2, Arg8]-vasopressin; 225 nmol/kg i.v.) had no effect on the response of immunoreactive cortisol to Poly I:C, suggesting that AVP was not involved in activation of the HPA axis. Poly I: C increased both body temperature and circulating immunoreactive prostaglandin E2; these responses were abolished by the cyclo-oxygenase inhibitor ketoprofen (3 mg/kg s.c.). The immunoreactive cortisol response to Poly I: C, however, remained after the administration of ketoprofen, indicating a prostaglandin (PG)-independent component. The immunoreactive cortisol levels in control, saline vehicle-treated, animals were reduced by both the CRF-41 receptor antagonist (α-helical CRF (9–41); 6·25 mmol/kg i.v.) and ketoprofen (3 mg/kg s.c.) indicating that this basal state is dependent on both CRF-41 and PGs.
Journal of Endocrinology (1992) 135, 69–75
Effects of basic fibroblast growth factor, transforming growth factor-β and nerve growth factor on the secretory function of the bovine corpus luteum in vitro
Authors: Miyamoto A. , Okuda K. , Schweigert F. J. , Schams D. 
Published: December 2008

ABSTRACT
The effects were investigated of basic fibroblast growth factor (bFGF), transforming growth factor-β (TGF-β) and nerve growth factor (NGF) on the release of progesterone and oxytocin from the bovine corpus luteum (CL) at different stages of the oestrous cycle. A microdialysis system (MDS) of CL and a cell culture system with a reduced number of endothelial cells were used.
In the MDS of CL from the mid-luteal stage (days 8–12 of the oestrous cycle), infusion with bFGF (0·1, 1, 10 and 100 ng/ml), TGF-β (0·1, 1 and 10 ng/ml) and NGF (0·1, 1, 10 and 100 ng/ml) for 30 min induced significant acute effects on the release of progesterone. Both bFGF and NGF stimulated the release of progesterone during peptide infusion, TGF-β and also bFGF in the period thereafter. This stimulation was dose-dependent during and after the infusion only for bFGF. This response pattern was observed at all luteal stages for the three growth factors, but bFGF was more stimulatory at the early (days 5–7) and mid-luteal stages during and after peptide infusion. The release of oxytocin was stimulated by bFGF in a dose-dependent manner. At the highest dose, bFGF, TGF-β and NGF stimulated the release of oxytocin throughout all three luteal stages. When luteal cells were cultured with growth factors, only TGF-β showed a dose-dependent inhibition of both basal and LH-stimulated progesterone as well as oxytocin release (measured between 48 and 52 h of culture). NGF had an inhibitory effect only on the basal release of oxytocin. bFGF had no effect on the release of either hormone under continuous stimulation in cell culture.
The results indicate that bFGF, TGF-β and NGF act directly and acutely on the secretory function of bovine CL in the MDS but also have long-term effects as shown in cell culture. bFGF appears to be an important autocrine/paracrine regulator of CL function, since local expression of its mRNA, peptide synthesis and its mitogenic and non-mitogenic actions have now been confirmed. Endothelial cells from the CL have been identified as target cells for bFGF. Differences observed between the two systems might thus be attributed to the presence or absence of cellto-cell contact and a reduced number of endothelial cells, as well as to the duration of peptide stimulation and medium changes every 24 h compared with the flow-through conditions in the MDS.
Journal of Endocrinology (1992) 135, 103–114
Effects of tri-iodothyronine and insulin-like growth factor-I (IGF-I) on alkaline phosphatase activity, [3H]thymidine incorporation and IGF-I receptor mRNA in cultured rat epiphyseal chondrocytes
Authors: Ohlsson C. , Nilsson A. , Isaksson O. , Bentham J. , Lindahl A. 
Published: December 2008

ABSTRACT
The effects of tri-iodothyronine (T3) and insulin-like growth factor-I (IGF-I) on [3H]thymidine incorporation, alkaline phosphatase (ALP) activity and IGF-I receptor mRNA levels were studied in rat epiphyseal chondrocytes cultured in monolayer.
Chondrocytes from enzymatically digested rat tibia epiphyseal growth plates were seeded in monolayer culture and precultured for 7–14 days in Ham's F-12 medium supplemented with 10% (v/v) newborn calf serum and 1% (v/v) of a serum substitute. After preculture the medium was changed to Ham's F-12 medium containing 1% (v/v) serum from hypophysectomized rats, and the effects of T3 and/or IGF-I on DNA synthesis ([3H]thymidine incorporation), ALP activity (a late marker of differentiated epiphyseal chondrocytes) and IGF-I receptor mRNA levels were studied.
ALP activity was increased by T3 in a dose-dependent manner with a maximal response at 10 μg T3/1 (678 ±86% compared with control culture). The increase in ALP activity was accompanied by a concomitant decrease in [3H]thymidine incorporation (52 ±14% compared with control culture). Human GH (hGH; 50 μg/l) and IGF-I (25 μg/l) had no stimulatory effect on ALP activity. However IGF-I (10 μg/l) exerted an inhibition on the T3 (10 μg/l)-induced increase in ALP activity (64 ± 9% compared with T3-treated culture). T3 (3 μg/l) inhibited the increase in [3H]thymidine incorporation caused by 25 μg IGF-I/l(51 ± 13% compared with IGF-I-treated culture). Furthermore, IGF-I receptor mRNA levels were increased by 10 μg T3/l (137 ±4·2% compared with control culture) while no effect of hGH (50 μg/l) or IGF-I (25 μg/l) was demonstrated.
Both T3 and IGF-I were shown to interact with epiphyseal chondrocytes and both substances seemed to affect cell proliferation and maturation and therefore longitudinal bone growth. Furthermore, the results indicated that IGF-I is important for proliferation of the cells while T3 initiates the terminal differentiation of epiphyseal chondrocytes.
Journal of Endocrinology (1992) 135, 115–123
A role for di-acetyl α-melanocyte-stimulating hormone in the control of cortisol release in the teleost Oreochromis mossambicus
Authors: Lamers A. E. , Flik G. , Atsma W. , Wendelaar Bonga S. E. 
Published: December 2008

ABSTRACT
In stressed tilapia, Oreochromis mossambicus, total α-melanocyte-stimulating hormone (α-MSH) levels and di-acetyl α-MSH/mono-acetyl α-MSH (di:mono) ratios are elevated. We therefore investigated the role of α-MSH in the regulation of the pituitary–interrenal axis. The corticotrophic activities of des-acetyl α-MSH, mono-acetyl α-MSH and di-acetyl α-MSH were compared. These forms of α-MSH were isolated from neurointermediate lobes and tested in a superfusion experiment with homologous interrenal tissue. The corticotrophic activity of di-acetyl α-MSH was the highest, followed by that of des-acetyl α-MSH and mono-acetyl α-MSH. Apparently, acetylation of α-MSH is of functional significance for corticotrophic action. Di-acetyl α-MSH proved to be about 100 times less potent than ACTH(1–39): the half-maximal stimulating concentrations for ACTH and di-acetyl α-MSH were 0·89 nmol/l and 110 nmol/l respectively. Surprisingly, a superfusate from neurointermediate lobes proved to be only about three times less active than a superfusate from the pituitary pars distalis, in which the corticotrophic activity is attributable to its ACTH content. When selectively stripped of all forms of α-MSH by passage through a Sepharose column coated with an antiserum against α-MSH the neurointermediate lobe superfusate was devoid of corticotrophic activity. Thus α-MSH appears to be the corticotrophic factor in the superfusate of the neurointermediate lobe. After the same treatment, the corticotrophic activity of the pars distalis superfusate was not affected. We conclude that (in vivo) an as yet unidentified factor is co-released with α-MSH from the neurointermediate lobe, and that this potentiates its corticotrophic activity.
Journal of Endocrinology (1992) 135, 285–292
Zona radiata proteins are synthesized by rainbow trout (Oncorhynchus mykiss) hepatocytes in response to oestradiol-17β
Authors: Oppen-Berntsen D. O. , Gram-Jensen E. , Walther B. T. 
Published: December 2008

ABSTRACT
The present study delineates the origin of the three major proteins constituting the rainbow trout (Oncorhynchus mykiss) zona radiata. Intraperitoneal administration of oestradiol-17β induced the appearance in the blood from juvenile fish (both sexes) of proteins immunoreactive to rabbit antisera against zona radiata proteins (zr proteins). These proteins had similar molecular weights to the zr proteins (a, 60 kDa; β, 55 kDa; and γ, 50 kDa). Primary hepatocyte cultures from fish treated with oestradiol-17β incorporated radioactive [35S] methionine into four major proteins with molecular weights of 160, 60, 55 and 50 kDa. Only the latter three proteins were specifically immunoprecipitated with antibodies to zr proteins. Furthermore, our data demonstrate that in such cultures the biosynthetic mole ratios of these secreted proteins (60, 55 and 50 kDa) are close to one. Control cultures from fish that had not been treated with oestradiol-17β failed to produce immunoreactive proteins. The data support the hypothesis that zr proteins are synthesized in a concerted manner in the liver during teleostean oogenesis and transported by the blood for deposition in ovarian follicles.
Journal of Endocrinology (1992) 135, 293–302
Different molecular forms of C-type natriuretic peptide isolated from the brain and heart of an elasmobranch, Triakis scyllia
Authors: Suzuki R. , Takahashi A. , Takei Y. 
Published: December 2008

ABSTRACT
The presence of a C-type natriuretic peptide (CNP) has been reported in the brain of mammals, birds, amphibians and teleost fishes, mostly as a 22-residue peptide (CNP-22). In the present study, we attempted to isolate natriuretic peptides from an elasmobranch, Triakis scyllia, using a chick rectum-relaxant assay, and different molecular forms of CNP were found in the brain and heart. Only CNP-22 was recovered from the brain, as is the case in other vertebrates. A large amount of prohormone (proCNP or CNP-115) and small amounts of its C-terminal peptides (CNP-38 and CNP-39) were isolated from the atrium and ventricle, however. No CNP-22 was recovered from the heart. Natriuretic peptides other than CNP were not isolated from Triakis heart and brain by the rectumrelaxant assay. The 22 residues at the C-terminal region of proCNP, i.e. CNP-22, were well conserved when Triakis and mammals were compared, although the sequence homology of the N-terminal segment of proCNP was very low. Not only was CNP-22 identical but the N-terminal segments of proCNP were also quite similar when Triakis and another elasmobranch, Scyliorhinus canicula, were compared. These data suggest that, in elasmobranchs, CNP is a primary hormone in the natriuretic peptide family, and also that CNP is processed differently in the brain and heart.
Journal of Endocrinology (1992) 135, 317–323
Intracellular pH and growth hormone-releasing factor-stimulated adenosine 3′5′-monophosphate, intracellular calcium and growth hormone release from rat anterior pituitary cells
Authors: Puttagunta A. L. , Chik C. L. , Girard M. , O'Brien L. , Ho A. K. 
Published: December 2008

ABSTRACT
In this study, we examined the effect of changes in intracellular pH (pHi) on basal and GH-releasing factor (GRF)-stimulated cyclic AMP (cAMP), intracellular Ca2+ and GH release using a static monolayer culture prepared from dispersed rat anterior pituitary cells. To modulate pHi, two approaches were used: variation of extracellular pH (pHo) and addition of sodium propionate and ammonium chloride which alter pHi directly. Direct pHi measurement with 2′7′-bis(carboxyethyl)-5(6)-carboxyfluorescein showed that for pHo values between 6·9 and 7·6, a change in pHo of 0·1 units resulted in a change in pHi of 0·045 units. Sodium propionate (30 mmol/l) reduced pHi by 0·06 units whereas ammonium chloride (30 mmol/l) increased pHi by 01 units. Increasing pHo from 6·6 to 7·8 enhanced the maximal GRF-stimulated cAMP and GH responses by 80% and 300% respectively, indicating that the GRF-stimulated cAMP and GH release were both pH-dependent. Acute elevation of pHo from 6·6 to 7·8 also increased basal GH release by sixfold. Reduction of pHi by sodium propionate, however, had no significant effect on GRF-stimulated cAMP levels while the corresponding GRF-stimulated GH release was reduced by up to 40%. In comparison, elevation of pHi by ammonium chloride enhanced the GRF-stimulated cAMP release by up to 75% and the corresponding increase in GH was less than 20%. When the relationship between pHi and intracellular Ca2+ was determined with the fluorescent Ca2+ indicator, Fura-2, it was found that increasing pHo and treatment with ammonium chloride increased intracellular Ca2+, while sodium propionate and reducing pHi had no effect on intracellular Ca2+. These results indicate that activation of adenylate cyclase and mobilization of intracellular Ca2+, two intracellular signalling pathways of importance to GH secretion, are both sensitive to changes in pHi.
Journal of Endocrinology (1992) 135, 343–352
Testosterone-induced suppression of self-healing Plasmodium chabaudi malaria: an effect not mediated by androgen receptors?
Authors: Benten W. P. M. , Wunderlich F. , Mossmann H. 
Published: December 2008

ABSTRACT
This study investigates whether androgen receptors (AR) mediate the suppressive effect of testosterone on self-healing Plasmodium chabaudi malaria. Our data show the following. (1) Female and castrated male mice of the inbred strain C57BL/10 self-heal and survive infections when challenged with 106 P. chabaudi-parasitized erythrocytes. However, self-healing is prevented when circulating testosterone levels are high as in intact males or in females and castrated males pretreated with 0·9 mg testosterone twice a week for 3 weeks. (2) The lethal outcome of P. chabaudi in intact males is not affected by different doses of AR blockers such as cyproterone acetate, cyproterone, flutamide and nilutamide when applied at least 3 weeks before infection and during infection. Also, these AR blockers do not impair the testosterone-induced lethal outcome of infections in testosterone-treated females and castrated males. (3) Tfm mice possessing mutant non-functional ARs and normal 'male' testosterone levels succumb to infection with P. chabaudi. However, the corresponding wild-type mice possessing functioning ARs are able to resist P. chabaudi infections at low circulating testosterone levels. (4) In contrast to testosterone, testosterone metabolites such as 5α-dihydrotestosterone, 5β-dihydrotestosterone, androsterone and 1-dehydrotestosterone cannot suppress self-healing in castrated male B10 mice. Our data suggest that testosterone suppresses the development of protective immunity against P. chabaudi malaria, and that this immunosuppressive effect of testosterone is not primarily mediated by the classical AR response.
Journal of Endocrinology (1992) 135, 407–413