bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the effects of insulin-like growth factors-I and -II on the human osteosarcoma cell line OHS-4
Authors: Fournier B. , Ferralli J. M. , Price P. A. , Schlaeppi J. M. 
Published: December 2008

ABSTRACT
The effects of insulin-like growth factor-I (IGF-I) and IGF-II on the human osteoblast cell-line OHS-4 were investigated. Both IGF-I and IGF-II stimulated cell proliferation at nanomolar concentrations and alkaline phosphatase activity was decreased in a dose-dependent manner with either IGF-I or IGF-II. The production of the bone-specific protein osteocalcin was not influenced by either IGF-I or IGF-II. However, they acted synergistically with 1,25-dihydroxyvitamin D3 at concentrations ranging from 10 to 100 nmol/l. Neither IGF-I nor IGF-II had an effect on either the basal or the parathyroid hormone-stimulated level of adenylate cyclase activity, and likewise they had no effect on phosphodiesterase activity. Binding and cross-linking experiments confirmed the presence of both type-I and type-II IGF receptors on the OHS-4 cells. The present study shows that IGF-I and IGF-II have similar effects on the parameters studied in these osteoblastic cells. They influenced both proliferation and differentiation markers.
Journal of Endocrinology (1993) 136, 173–180
Corticotrophin-releasing factor as a mediator of the acute-phase response in rats, mice and rabbits
Authors: Hagan P. M. , Poole S. , Bristow A. F. 
Published: December 2008

ABSTRACT
The acute-phase response involves a number of separate physiological components, including induction of acute-phase protein synthesis by the liver. This response can be induced in vivo by administration of the endogenous leucocytic mediator interleukin-1β. A number of in-vivo effects of interleukin-1β have been reported to be mediated by corticotrophin-releasing factor (CRF), including activation of the hypothalamo-pituitary-adrenal axis and induction of fever, and in this report we have examined a possible involvement of CRF in mediating interleukin-1β-induced acute-phase protein synthesis.
Interleukin-1β stimulated the elevation of species-specific plasma acute-phase proteins in rats, mice and rabbits. Co-injection of interleukin-1β with the specific CRF receptor antagonist α-helical-CRF9–41 NH2 abolished or attenuated acute-phase protein synthesis induced by interleukin-1β in all three species for up to 12 h after injection. The inhibitory effect of α-helical-CRF9–41NH2 was reduced or absent 24 h after injection. Neutralizing anti-CRF antisera had no effect on acute-phase protein synthesis in the mouse and, paradoxically, potentiated acute-phase protein synthesis induced by interleukin-1β in the rat. These results indicate a possible mediatory role for CRF in regulation of acute-phase protein synthesis, and suggest that CRF may mediate induction of acute-phase protein synthesis by a different mechanism from that involved in regulation of corticotrophin secretion.
Journal of Endocrinology (1993) 136, 207–216
Arginine vasopressin-induced natriuresis in the anaesthetized rat: involvement of V1 and V2 receptors
Authors: Smith C. P. , Balment R. J. 
Published: December 2008

ABSTRACT
The present study was undertaken to determine the involvement of the two established vasopressin receptor subtypes (V1 and V2) in arginine vasopressin (AVP)-induced natriuresis and also to determine whether changes in mean arterial pressure (MAP) and/or the renally active hormones atrial natriuretic peptide (ANP), angiotensin II (AII) and aldosterone are a prerequisite for the expression of AVP-induced natriuresis.
In Sprague–Dawley rats which were anaesthetized with Inactin (5-ethyl-5-(1′-methylpropyl)-2-thiobarbiturate) and infused with 0·077 mol NaCl/l, infusion of 63 fmol AVP/min was found to be natriuretic whereas an approximately equipotent dose of the specific V2 agonist [deamino-cis1, d-Arg8]-vasopressin (dDAVP) did not induce natriuresis. The specific V1 antagonist [β-mercapto-β,β-cyclopenta-methylene-propionyl1, O-Me-Tyr2, Arg8]-vasopressin when administered prior to infusion of 63 fmol AVP/min did not inhibit AVP-induced natriuresis. AVP-induced natriuresis was not accompanied by changes in MAP or in the plasma concentrations of the renally active hormones ANP, AII or aldosterone.
These results suggest that neither the V1 nor the V2 receptor subtypes are involved in AVP-induced natriuresis. In addition, it was found that changes in MAP, plasma ANP, All or aldosterone concentrations were not a prerequisite for AVP-induced natriuresis.
Journal of Endocrinology (1993) 136, 283–288
Receptor binding of insulin-like growth factor-I to mammary microsomes from non-pregnant, pregnant and lactating sheep
Authors: Winder S. J. , Wheatley S. D. , Forsyth I. A. 
Published: December 2008

ABSTRACT
Sucrose density centrifugation was used to prepare a partially purified membrane fraction from the mammary glands of non-pregnant, pregnant and lactating sheep. The binding of125 I-labelled insulin-like growth factor-I (IGF-I) was dependent on membrane protein concentration, pH, time and temperature. The binding showed the characteristics of a type-1 IGF receptor, being displaced by IGF-I (median effective dose (ED50) 0·55 nmol/l), less effectively by IGF-II (ED50 8·8 nmol/l) and least effectively by insulin. Glucagon, ovine prolactin and ovine placental lactogen could not displace binding. A molecular weight of 135 000 was determined by affinity cross-linking using disuccinimidyl suberate; this was consistent with the reported size of the type-1 receptor α-subunit. Scatchard analysis was used to determine binding affinity and numbers of IGF-I-binding sites. A single class of high-affinity binding sites was found in all physiological states. In non-pregnant sheep and sheep at days 40, 75 and 110–120 of pregnancy and at term, the binding affinity was similar (apparent dissociation constant (Kd) 2·73 ±0·31 nmol/l, n = 22). In lactating sheep (weeks 1, 4 and 10), the binding affinity was significantly (P = 0·02) higher (Kd 0·77± 0·06 nmol/l n = 9). Binding capacity was similar in non-pregnant and pregnant sheep (1005 ± 113 fmol/mg, n = 19), but fell by parturition and remained low in lactation (570±52 fmol/mg membrane protein, n = 12). The results suggest that the mammary growth of pregnancy is not regulated at the level of the type-1 IGF receptor.
Journal of Endocrinology (1993) 136, 297–304
Variations in oxytocin secretion during the 4-day oestrous cycle of the rat
Authors: Windle R. J. , Forsling M. L. 
Published: December 2008

ABSTRACT
Oxytocin concentrations in the plasma, pituitary and hypothalamus of female rats were determined in the morning and evening over the 4-day oestrous cycle. Vasopressin concentrations were also determined to allow calculation of the ratios of the two hormones. The results were compared with those from male rats. Plasma oxytocin concentrations were significantly higher in the evening than in the morning on the day of oestrus. Although the evening concentration achieved was similar on each day of the cycle, morning plasma oxytocin concentrations showed a progressive rise from oestrus to pro-oestrus so that no significant diurnal increases were observed on the other days of the cycle. Vasopressin concentrations in the plasma were also seen to increase over the days of oestrus, dioestrus day 1 and dioestrus day 2. On pro-oestrus the plasma concentrations of vasopressin remained unchanged. The ratio of oxytocin:vasopressin fell during the light hours of the cycle. The hypothalamic content of both hormones showed a rise during the hours of daylight parallel to that seen in the plasma, whereas the pituitary content fell over the same period. The diurnal pattern of hormone release observed in male rats was similar to that in females at oestrus. However, the plasma oxytocin concentrations were significantly higher in the male.
The plasma clearance rate of vasopressin did not vary significantly during the oestrous cycle. However, the plasma clearance rate for oxytocin did show significant variation, being highest on dioestrus day 1 and lowest on dioestrus day 2.
Journal of Endocrinology (1993) 136, 305–311
Specificity studies of particulate binding sites for steroid hormones in subcellular fractions of the porcine corpus luteum
Authors: Bramley T. A. , Menzies G. S. 
Published: December 2008

ABSTRACT
We have studied the binding of a number of radiolabelled steroids and lipophilic substances to porcine corpus luteum (CL) particulate fractions. Following preincubation of CL homogenates with radiolabelled progesterone or pregnenolone prior to fractionation on continuous sucrose density gradients, a broad peak of binding was observed associated with a particulate fraction of buoyant density 1·05–1·10 g/cm3. Progesterone content also peaked at a similar buoyant density (1·06–1·12 g/cm3). Pretreatment of luteal homogenates with digitonin perturbed the buoyant density of the progesterone-binding particulate fraction to 1·10–1·14 g/cm3 and sharpened the binding peak. Progesterone content was also perturbed to a similar extent by digitonin pretreatment, without release of the steroid. Oestrogens were also sequestered by this fraction, but steroid precursors (cholesterol, cholesterol ester), corticosteroids (cortisol, corticosterone), sterol conjugates (oestrone sulphate, pregnanediol glucuronide) and other lipophilic substances (arachidonic acid, phospholipid, prostaglandins E1, E2 and F2α) were not bound. Androgens were bound weakly by fractions from control gradients but, in the presence of digitonin, significant binding could be demonstrated. Radiolabelled steroids were shown to interact directly with luteal membrane fractions, rather than interacting first with cytosolic steroid receptors which then bound to membranes. Furthermore, [3H]progesterone was not bound by porcine granulosa cell particulate fractions. These observations suggest that this fraction may be involved in sequestration or packaging of progesterone for secretion by the luteal cell.
Journal of Endocrinology (1993) 136, 371–380
Paracrine effects via the epidermal growth factor receptor in the rodent testis may be mediated by non-Leydig interstitial cells
Authors: Moore A. , Morris I. D. 
Published: December 2008

ABSTRACT
The epidermal growth factor (EGF) receptor is expressed in a wide variety of cell types and is known to be present in the testis of many species including man. In the present study, specific 125 I-labelled EGF binding was observed in isolated interstitial cell preparations from both the intact and Leydig cell-depleted rat testis. It was demonstrated that the population of cells to which 125I-labelled EGF binds has a different buoyant density from either of the two adult Leydig cell populations, and remains unchanged in the absence of Leydig cells following in-vivo treatment with ethane dimethane sulphonate (EDS). Cells of this density (1·064 g/ml) identified by electron microscopy were fusiform mesenchymal cells, identical to those suggested by others to be able to differentiate into Leydig cells in vitro, i.e. Leydig cell precursors. In a culture system using two interstitial cell preparations of different buoyant densities from immature rats, both EGF and transforming growth factor-α (TGF-α) caused increased [3H]thymidine incorporation in the less dense cell preparation. TGF-α was more potent than EGF. EGF increased testosterone production in both fractions in amounts which could be related to the amount of 3β-hydroxysteroid dehydrogenase (3β-HSD)-positive cells. This study demonstrated that rat Leydig cells (defined as those cells which bind 125I-labelled human chorionic gonadotrophin, have distinct buoyant densities, are 3β-HSD positive and are sensitive to EDS), do not bind 125I-labelled EGF. Rather, EGF binds to a mesenchymal cell without LH receptors which is resistant to EDS. Growth factors which act via the EGF receptor increased [3H]thymidine incorporation in a Leydig cell-depleted interstitial fraction which may reflect an action upon the progenitor of the mature Leydig cell.
Journal of Endocrinology (1993) 136, 439–446
Inhibitory effects of insulin-like growth factor (IGF)-binding proteins-1 and -3 on IGF-activated glucose consumption in mouse BALB/c 3T3 fibroblasts
Authors: Okajima T. , Iwashita M. , Takeda Y. , Sakamoto S. , Tanabe T. , Yasuda T. , Rosenfeld R. G. 
Published: December 2008

ABSTRACT
We have examined the biological effects of insulinlike growth factor-binding proteins (IGFBPs) on insulin-like growth factor (IGF)-activated glucose consumption in a BALB/c 3T3 subline. The method employed was a colorimetric measurement of glucose consumption, allowing the detection of changes from the initial glucose concentration in conditioned medium, following the addition of IGFs and IGFBPs. Human IGFBP-1, purified from amniotic fluid, inhibited IGF-activated glucose consumption, although it had no effect on insulin-activated glucose consumption. The median effective dose (ED50) of IGFBP-1 to cause inhibitory effects on IGF-activated glucose consumption was 100–200 μg/l and was similar for both IGF-I and IGF-II at a concentration of 1·0 μg IGF/1. Therefore, at IGF concentrations of comparable activity, the inhibitory effects of IGFBP-1 were greater for IGF-I than for IGF-II, because of the higher activity of IGF-I in this assay. Recombinant human IGFBP-3 also inhibited IGF-activated glucose consumption, without affecting insulin-stimulated glucose consumption. The inhibitory effects of IGFBP-3 were greater for IGF-II than for IGF-I when IGFBP-3 was coincubated with either of the IGFs, at both IGF concentrations of comparable activity and equivalent molar concentrations. Thus, it became clear that the inhibitory effects of these IGFBPs on IGF biological action depended primarily upon their affinity for the specific IGF ligand and molar ratio of IGFBP/IGF peptide. Interestingly, when cells were pretreated with IGFBP-3, prior to the simultaneous addition of IGFs and IGFBP-3, the inhibitory effect was higher for IGF-I than for IGF-II. Either no effect or a minor inhibitory effect on IGFactivated glucose consumption was detected with IGFBP pretreatment alone. When the ED50 for inhibition of IGF action by IGFBPs in this in-vitro assay was compared with the physiological concentrations of IGFs and IGFBPs in normal human serum and in amniotic fluid, it was estimated that the IGFBP-1 concentration present in serum was not sufficient to modulate IGF action effectively while the concentration in amniotic fluid was enough for effective suppression. IGFBP-3 exhibited an ED50 low enough to suppress IGF-II and possibly IGF-I action when cells were pretreated with IGFBP-3. Thus, our data suggested that IGFBP-1 in amniotic fluid and IGFBP-3 in serum could be a potent inhibitor for IGF action. IGFBP-1 in serum, however, may not be able to function as a direct inhibitor under physiological conditions but, rather, may modulate IGF action together with other IGFBPs.
Journal of Endocrinology (1993) 136, 457–470
Oxytocin-stimulated phosphoinositide hydrolysis in human myometrial cells: involvement of pertussis toxin-sensitive and -insensitive G-proteins
Authors: Phaneuf S. , Europe-Finner G. N. , Varney M. , MacKenzie I. Z. , Watson S. P. , López Bernal A. 
Published: December 2008

ABSTRACT
Phosphoinositide hydrolysis is important in mediating the actions of oxytocin and prostaglandin (PG) F2α on uterine contractions during labour. We have measured the effect of oxytocin, PGF2α and other agents on the formation of inositol phosphates (IPs) in cultured human myometrial cells labelled with [3H]inositol and on changes in intracellular free Ca2+ concentration ([Ca2 + ]i) in cells loaded with Fura-2.
Oxytocin induced the formation of [3H]IPs in a concentration-dependent manner with an EC50 (concentration of agonist producing 50% of the maximal response) of 1·4 ±0·5 nmol/l (mean ± s.e.m.). The maximal response was obtained with 1 μmol oxytocin/l and represented a stimulation of 670% over basal. PGF2α also stimulated the formation of [3H]IPs and the response at 1 μmol/l was a 204% stimulation over basal. The effects of PGF2α were independent of extracellular Ca2 + but the effect of oxytocin was reduced with low extracellular Ca2 +. Cyclic AMP formation, induced by forskolin or PGE2, had no effect on the stimulated levels of [3H]IPs. Pertussis toxin (PT) reduced the oxytocin-stimulated formation of [3H]IPs in a concentration-dependent manner. The maximal effect of PT resulted in an 80% reduction in the formation of [3H]IPs. However, PGF2α stimulation was not affected by PT treatment.
To analyse the action of PT further, we studied its effect on oxytocin-induced changes in [Ca2 + ]i. The basal [Ca2 +]i was 112 ±4 nmol/l (n=225 cells) and was not affected by PT treatment (109 ± 3 nmol/l; n= 200 cells). In the absence of PT, 1 μmol oxytocin/l increased [Ca2 + ]i to a peak of 522 ±26 nmol/l, and in PT-treated cells, the [Ca2 + ]i peak was reduced to 348 ± 16 nmol/l. Similar inhibitory effects of PT were obtained at oxytocin concentrations ranging from 1 to 100 nmol/l.
Our data suggest that in human myometrial cells, the oxytocin-induced production of [3H]IPs and increase in [Ca2 + ]i are mediated by a PT-sensitive G-protein. However, a significant fraction of the oxytocin response appears to be mediated by a PT-insensitive G-protein, possibly a member of the Gq family.
Journal of Endocrinology (1993) 136, 497–509
Involvement of inhibin in the regulation of FSH secretion in prepubertal bulls
Authors: Kaneko H. , Yoshida M. , Hara Y. , Taya K. , Araki K. , Watanabe G. , Sasamoto S. , Hasegawa Y. 
Published: December 2008

ABSTRACT
To investigate the physiological importance of inhibin in the regulation of FSH secretion in prepubertal bulls, animals (6-month-old) were passively immunized against inhibin. Five animals were given an i.v. bolus injection of 50 ml inhibin antiserum raised against bovine 32 kDa inhibin in a castrated male goat, and four bulls were given the same amount of castrated male goat serum (control serum) as controls. Treatment with the inhibin antiserum resulted in a marked increase (P < 0·01) in plasma concentrations of FSH within 12 h compared with control animals, and FSH levels in immunized animals remained high until 168 h after the injection. Concentrations of plasma LH and testosterone in the immunized animals were not different from those in the control animals. The present findings provide strong evidence that inhibin plays an important role in the inhibitory regulation of FSH secretion in prepubertal bulls.
Journal of Endocrinology (1993) 137, 15–19
Opioids and testicular activity in the frog, Rana esculenta
Authors: Facchinetti F. , Genazzani A. R. , Vallarino M. , Pestarino M. , Polzonetti-Magni A. , Carnevali O. , Ciarcia G. , Fasano S. , D'Antonio M. , Pierantoni R. 
Published: December 2008

ABSTRACT
The presence and activity of brain, pituitary and testicular β-endorphin (β-EP)-like material have been studied in the frog, Rana esculenta, using reverse-phase high-pressure liquid chromatography, coupled with radioimmunoassay and immunocytochemistry. In-vivo and in-vitro treatments with naltrexone were carried out to assess the putative physiological activity of opioid peptides.
β(1–31) and (1–27), together with their acetylated forms, have been identified in brain, pituitary and testis. In particular, β-EP(1–31) concentrations peaked during July in the brain and pituitary, whilst in testes maximum concentrations were found in April and November. β-EP immunoreactivity was present in the brain within the nucleus preopticus and nucleus infundibularis ventralis while positive fibres in the retrochiasmatic regions projected to the median eminence. In the testis, interstitial cells, canaliculi of the efferent system, spermatogonia and spermatocytes showed positive immunostaining for β-EP. In intact animals, naltrexone treatment increased plasma and testicular androgen levels and this effect was confirmed in in-vitro incubations of minced testes. Naltrexone also induced a significant increase in germ cell degeneration.
Our results indicated that an opioid system modulates the hypothalamus-pituitary-gonadal axis in the frog, Rana esculenta and, for the first time, we have shown that the testicular activity of a non-mammalian species may be regulated by opiates locally.
Journal of Endocrinology (1993) 137, 49–57
Pro-oestrous-specific role for polyamines in mediating the secretion of prolactin induced by thyrotrophin-releasing hormone in the rat
Authors: Wynne-Jones G. A. , Gurney A. M. 
Published: December 2008

ABSTRACT
The activity of ornithine decarboxylase (ODC) in the rat anterior pituitary gland varies during the oestrous cycle, with a rise in activity seen at pro-oestrus. This enzyme, which is rate-limiting for the synthesis of the polyamines, can be specifically and irreversibly blocked by α-difluoromethylornithine (DFMO). A previous study showed that when this drug was administered to rats in vivo on the afternoon of pro-oestrus, it suppressed the normal surge in plasma prolactin levels that occurred later that day. The effect of DFMO was associated with reduced levels of putrescine in the anterior pituitary gland, suggesting that ODC activity in the lactotroph might be involved in the prolactin surge. We have examined the effects of DFMO on the secretion of prolactin from anterior pituitary cells, isolated either from male rats or from females at different stages of the oestrous cycle. The drug was found to reduce prolactin secretion stimulated by thyrotrophin-releasing hormone (TRH), but only in cells isolated from pro-oestrous animals and only for 2 days after cell isolation. Basal secretion was unaffected by DFMO. The results imply that ODC is important for TRH-stimulated prolactin secretion at pro-oestrus, and it is specific for pro-oestrus. The prolactin surge could therefore be influenced by this ODC-dependent effect of TRH. The pro-oestrous-specific response to TRH may be a consequence of the increased ODC activity seen at this time. Alternatively, the increased ODC activity could be a consequence of coupling to TRH receptors, which are known to increase in number at pro-oestrus.
Journal of Endocrinology (1993) 137, 133–139
Effects of melanocyte-stimulating hormone on tyrosinase expression and melanin synthesis in hair follicular melanocytes of the mouse
Authors: Burchill S. A. , Ito S. , Thody A. J. 
Published: December 2008

ABSTRACT
Tyrosinase mRNA, synthesis and activity were measured in the skin during the first 2 weeks of life of C3H-HeAvy mice. Tyrosinase mRNA levels were found to peak on days 3–4 and were followed by increases in tyrosinase synthesis and activity which peaked on days 6–7 and 7–8 respectively. These changes in tyrosinase expression were presumably associated with the growth of the first coat of hair that in neonatal C3H-HeAvy mice is yellow in colour as a result of the increased proportion of phaeomelanin. By the time hair growth had ceased there was no expression of tyrosinase at both mRNA and protein levels. Daily administration of α-melanocyte stimulating hormone (α-MSH) enhanced the expression of tyrosinase mRNA transcripts, tyrosinase synthesis and activity. The increase in tyrosinase activity paralleled the change in the amount of tyrosinase, suggesting that the primary action of α-MSH is to stimulate new synthesis of the enzyme. This induction of tyrosinase was associated with the growth of hair that was darker in colour than that of the controls and contained an increased proportion of eumelanin. This increase in eumelanin reflected a decrease in phaeomelanin content. It was concluded that, through its actions on the enzyme tyrosinase, α-MSH is able to switch the synthesis of phaeomelanin to that of eumelanin in hair follicular melanocytes.
Journal of Endocrinology (1993) 137, 189–195