bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stimulation of ovine placental lactogen secretion by arachidonic acid
Authors: Huyler S. E. , Butler W. R. , Grandis A. , Mann C. , Figueroa J. P. , Nathanielsz P. W. , Mitchell M. , Handwerger S. 
Published: December 2008

ABSTRACT
To determine whether arachidonic acid stimulates the secretion of ovine placental lactogen (oPL), arachidonic acid was infused as an intravenous bolus into pregnant ewes and fetuses. Plasma oPL concentrations were determined in mothers and fetuses before and for 5 h after infusion. The administration of 12·5 mg arachidonic acid (0·15−0·2 mg/kg, n = 11 experiments) to the pregnant ewes caused an increase in maternal plasma oPL concentrations of 73·9±15·6% (s.e.m.) and 60·8±18·1% above the pretreatment concentrations at 4 and 5 h respectively P<0·01 in each instance). The infusion of 25 mg arachidonic acid (n = 8) caused increases of 96·0±19·1% and 100·3±26·4% (P<0·005), and the stimulation was not inhibited by the cyclo-oxygenase inhibitors indomethacin and ibuprofen. In contrast to arachidonic acid, vehicle alone or palmitic acid had no effects on plasma oPL concentrations. Despite the increase in maternal plasma oPL concentrations, plasma oPL concentrations in the fetus remained unchanged after the maternal infusions. The infusion of arachidonic acid (0·5–1·5 mg/kg) directly into six fetuses had no effects on either fetal or maternal oPL concentrations. These studies indicate that (1) arachidonic acid stimulates maternal plasma oPL concentrations but has no effect on fetal oPL concentrations and (2) the stimulation of oPL secretion is not due to the conversion of arachidonic acid to prostaglandins or other cyclo-oxygenase products.
J. Endocr. (1985) 106, 43–47
[3H]Prostaglandin accumulation in vitro by baboon uterus
Authors: Jones M. A. , Kuehl T. J. , Harper M. J. K. 
Published: December 2008

ABSTRACT
Uteri from mature baboons at various stages of the menstrual cycle were collected at autopsy. Transverse slices of the uteri were incubated with [3H]prostaglandins in Tyrode's buffer. Bound and free ligands were separated by filtration. Prostaglandin (PG) accumulation by the tissue slices was evaluated as a function of incubation time, PG type and concentration, temperature, wet weight of tissue and stage of the menstrual cycle. There was no significant difference in PG accumulation in response to PG type (PGE2 or PGF2α) or stage of the menstrual cycle. These results from baboon uteri were compared with those using baboon oviducts and also rabbit uteri and oviducts. Unlike the rabbit tissues, the baboon oviducts and uterine tissues did not exhibit specific net accumulation of prostaglandins.
J. Endocr. (1985) 106, 49–53
Effect of somatostatin and thyrotrophin-releasing hormone on the levels of growth hormone in the circulation of the chronically catheterized pig fetus in utero
Authors: Spencer G. S. G. , Garssen G. J. , Colenbrander B. , Meijer J. C. 
Published: December 2008

ABSTRACT
The effects of i.v. administration of thyrotrophin-releasing hormone (TRH) and of somatostatin on circulating plasma levels of porcine GH in the chronically catheterized pig fetus have been examined. Growth hormone levels increased markedly (P<0·01) following TRH administration, but there was no change in thyroxine levels by 1 h after treatment. Administration of somatostatin caused a significant (P<0·05) decrease in mean GH levels, but the response was variable between pigs. Saline administration had no significant effect on GH levels. These results suggest that the mechanisms regulating postnatal GH release are present in the fetal pig, but may not be fully developed 8–12 days before delivery.
J. Endocr. (1985) 106, 121–124
Evidence for a stimulatory β-adrenergic component in the release of the ovulatory LH surge in pro-oestrous rats
Authors: Al-Hamood M. H. , Gilmore D. P. , Wilson C. A. 
Published: December 2008

ABSTRACT
The effect on ovulation of intraventricular infusions of noradrenaline, adrenaline and various pharmacological agents acting on the adrenergic receptor subtypes were investigated in cyclic female rats on the day of pro-oestrus. The inhibitory effects on ovulation of the different infusions were monitored by administering the drugs before 11.00 h (several hours before the critical period for the ovulatory LH surge). In experiments designed to show how the drugs under investigation might stimulate ovulation, pentobarbitone sodium (35 mg/kg) was given at 14.30 h; this anaesthetic inhibits ovulation and its effects can be overcome by substances that advance the preovulatory LH surge.
Noradrenaline (an α-agonist) stimulated ovulation when administered on the morning of pro-oestrus to rats injected with pentobarbitone early in the afternoon of the same day. Phenoxybenzamine and phentolamine (non-selective α-antagonists) and clonidine (a selective α2-agonist) all inhibited ovulation when infused on the morning of pro-oestrus. Yohimbine (a moderately selective α2-antagonist) neither stimulated nor inhibited ovulation.
Both isoprenaline (a non-selective β-agonist) and fenoterol (a selective β2-agonist) stimulated ovulation in pentobarbitone-treated rats when administered on the morning of pro-oestrus and fenoterol was also able to overcome the pentobarbitone block when infused later in the afternoon. Propranolol (a non-selective β-antagonist) and metoprolol (a selective β1-antagonist) were stimulatory only when administered in the afternoon.
Adrenaline (both an α- and β-agonist), prenalterol (a selective β1-agonist), atenolol (a selective β1-antagonist) and ICI 118, 551 (a selective β2-antagonist) neither stimulated nor inhibited ovulation.
The effect of intraventricular infusions of two selected β-adrenergic drugs was also investigated in ovariectomized rats primed with 2 μg oestradiol benzoate 48 h previously. Isoprenaline and fenoterol were able to stimulate LH release at 40 and 10 min respectively after their administration.
These results suggest a possible involvement of a stimulatory β2-adrenergic component in the neural regulation of the preovulatory LH surge along with the well-documented α-stimulatory component, which together may mask the possible inhibitory effects of a β1-adrenergic system.
J. Endocr. (1985) 106, 143–151
Peroxidase-catalysed iodotyrosine formation in dispersed cells of mouse extrathyroidal tissues
Authors: Banerjee R. K. , Bose A. K. , Chakraborty T. K. , De S. K. , Datta A. G. 
Published: December 2008

ABSTRACT
A method has been developed for the isolation of cells, high in iodine uptake and peroxidase activity, from the stomach and submaxillary gland of mice. The isolated cells could produce protein-bound monoiodotyrosine, di-iodotyrosine and an unknown iodocompound. The reactions were catalysed by peroxidase and were sensitive to antithyroid drugs and haemoprotein inhibitors but were insensitive to TSH. In-vitro iodination of stomach or submaxillary soluble proteins with the respective peroxidase yielded similar iodocompounds while thyroxine was produced when thyroglobulin was used instead.
J. Endocr. (1985) 106, 159–165
Prolactin permits the expression of a circadian variation in lipogenic responsiveness to insulin in hepatocytes of the golden hamster (Mesocricetus auratus)
Authors: Cincotta A. H. , Meier A. H. 
Published: December 2008

ABSTRACT
Lipogenesis was determined at two times (07.00 and 16.00 h) during a 14-h daily photoperiod (08.00–22.00 h) in freshly prepared hamster hepatocytes with or without addition of insulin. The hamsters were pretreated for 5 days with bromocriptine (to inhibit prolactin secretion), bromocriptine and prolactin replacement, or control saline injections. Lipogenesis was determined by incorporation of [14C]acetate into total cell lipids over a 30-min interval. Lipogenesis was three times greater at 07.00 than at 16.00 h and insulin was effective in stimulating further lipogenesis only at 07.00 h. Bromocriptine pretreatment severely reduced incorporation of radiolabel at 07.00 h to levels comparable with controls at 16.00 h and completely inhibited the stimulatory effect of insulin at 07.00 h. Prolactin replacement in bromocriptine-treated hamsters reversed the inhibitory effect of bromocriptine on hepatocyte lipogenesis and promoted dramatic lipogenic responses to insulin at 07.00 h. These results indicate that insulin stimulates hepatic lipogenesis only during some portion of a day and that prolactin facilitates the lipogenic response.
J. Endocr. (1985) 106, 173–176
Central opioids: a possible role in parturition?
Authors: Leng G. , Mansfield S. , Bicknell R. J. , Dean A. D. P. , Ingram C. D. , Marsh M. I. C. , Yates J. O. , Dyer R. G. 
Published: December 2008

ABSTRACT
Pregnant rats were implanted with subcutaneous minipumps to deliver either naloxone or saline. The time-course of subsequent parturition was different between the two groups: the interval between successive births was significantly shorter for the naloxone-treated rats. This supports the hypothesis that the opioid innervation of the neurohypophysis, which is known to influence oxytocin release profoundly, has a physiological role in parturition. To test the further hypothesis that this role is particularly important in a stressful environment, pregnant rats, again implanted with minipumps, were regularly transferred, at 15-min intervals beginning with the birth of the first pup, between their normal cage and the unfamiliar environment of a glass observation chamber. No difference was noted between the time-courses of parturition for the naloxone- and saline-treated groups, although the time-courses were markedly altered from those observed in rats not subjected to an unfamiliar environment. We conclude that opioid modulation of oxytocin release may play a role in 'spacing' the delivery of successive births during normal parturition.
J. Endocr. (1985) 106, 219–224
Changes in 3β-hydroxy-Δ5-steroid dehydrogenase activity in granulosa tissue during the ovulatory cycle of the laying hen (Gallus domesticus)
Authors: Armstrong D. G. 
Published: December 2008

ABSTRACT
The object of this study was to examine changes in the activity of granulosa 3β-hydroxy-Δ5-steroid dehydrogenase during the ovulatory cycle of the domestic fowl. The enzyme activity in granulosa tissue from the largest follicle increased significantly during the period 8–14 h before an expected ovulation. The increase in activity occurs before the preovulatory surge of LH and near the time of lights off. During the 4–8 h period before an ovulation, i.e. the time of maximal plasma LH concentrations, 3β-hydroxy-Δ5-steroid dehydrogenase activity decreased in granulosa tissue from the largest follicle. This observation is explained by proposing that the enzyme is inhibited by the large amounts of progesterone found in the tissue at this time.
The results indicate that important biochemical changes are taking place within granulosa tissue of the largest ovarian follicle before the preovulatory LH surge.
J. Endocr. (1985) 106, 269–273
Identification of amino acid transport systems stimulated by FSH in rat testes
Authors: da Cruz Curte A. , Wassermann G. F. 
Published: December 2008

ABSTRACT
Testes of 12-day-old rats preincubated (90 min) and incubated (60 min) with FSH in Krebs–Ringer bicarbonate buffer (KRB) increased their uptake of [14C]methylaminoisobutyric acid and [14C]aminoisobutyric acid. The hormone was ineffective in sodiumfree KRB. Transport of [14C]aminoisobutyric acid in the presence of methylaminoisobutyric acid (MeAIB; 30 mmol/l) was not stimulated by FSH, and uptake of [14C]cycloleucine was not increased by FSH in any of the experimental conditions used.
It was concluded that in immature rat testes FSH affects only the sodium-dependent system which permits the transport of MeAIB (transport system A) and has no effect on the sodium-independent system which prefers leucine (system L) or the sodium-dependent system which does not transport MeAIB (system ASC).
J. Endocr. (1985) 106, 291–294
Relationship of oestrogen and progesterone and their oviductal receptors in laying and non-laying 5-year-old hens
Authors: Okulicz W. C. , Fournier D. J. , Esber H. , Fredrickson T. N. 
Published: December 2008

ABSTRACT
This study focuses on the relationship of ageing to reproductive function in the domestic hen. Reproductive function was assessed by egg-laying records of hens from the same flock of 4, 5 and 6 years of age. Egg laying decreased with advancing age and the percentage of non-laying hens increased. During an ovulatory cycle, plasma levels of oestrogen and progesterone (including the preovulatory surge) were similar in both the 5-year-old and 1-year-old laying hens. In both young and old non-laying hens, the preovulatory surge of progesterone was absent. Levels of oestrogen were similar for all hens, but the oestrogen-dependent oviduct was atrophied in non-laying 5-year-old hens. This reduction in oviductal size was correlated with reduced levels of magnal nuclear oestrogen receptor and cytosol progesterone receptor. These results suggest a refractoriness of the oviduct to oestrogen stimulation in the ageing hen.
J. Endocr. (1985) 106, 343–348
An examination of the proposed roles of placental lactogen in the ewe by means of antibody neutralization
Authors: Waters M. J. , Oddy V. H. , McCloghry C. E. , Gluckman P. D. , Duplock R. , Owens P. C. , Brinsmead M. W. 
Published: December 2008

ABSTRACT
The physiological role of placental lactogen (PL; chorionic somatomammotrophin) in the ewe has been investigated by infusion of ewes (n = 3) on day 131 of pregnancy with sufficient ovine PL (oPL) antibody to neutralize circulating oPL for at least 12 h. Effectiveness of the antibody neutralization was defined both in vitro and in vivo according to rigorous criteria. Control ewes (n = 3) were infused simultaneously with an equivalent amount of pooled goat gamma globulin. Since both sets of ewes had previously been catheterized with jugular, utero-ovarian and femoral vein catheters and a femoral arterial catheter, it was possible to measure whole body glucose kinetics as well as muscle and uterine glucose, free fatty acid (FFA) and 3-hydroxybutyrate extraction. In addition, plasma levels of insulin, GH, prolactin, insulin-like growth factor-I (IGF-I), IGF-II, progesterone and cholesterol were determined in femoral arterial samples.
Neutralization of maternal oPL did not significantly affect whole body glucose metabolism, uterine and muscle glucose extraction, or 3-hydroxybutyrate extraction by muscle. A trend towards lower plasma FFA levels was observed after prolonged infusion, but was not statistically significant. However, plasma insulin levels rose significantly during antibody infusion after an early fall. These observations are rationalized in terms of the known requirements of ruminant metabolism during pregnancy, and contrasted with the accepted model for the role of human PL in the metabolic adjustments of pregnancy.
No change in plasma IGF-I, IGF-II or GH was observed, providing no support for the concept that oPL is responsible for maternal somatomedin generation during pregnancy. Similarly, plasma prolactin did not differ between antibody-treated and control groups. Finally, antibody neutralization had no influence on either plasma progesterone or cholesterol, mitigating against a role for oPL in progesterone production during late pregnancy in the ewe.
J. Endocr. (1985) 106, 377–386
SALMONID MELANIN-CONCENTRATING HORMONE INHIBITS CORTICOTROPHIN RELEASE
Authors: Baker B.I. , Bird D.J. , Buckingham J.C. 
Published: December 2008

ABSTRACT
Melanin-concentrating hormone (MCH) is a neural peptide associated with colour change in fishes. We show here that it also inhibits corticotrophin (ACTH) secretion. Synthetic salmonid MCH at a concentration of 100 pmol/l reduced the in-vitro release of ACTH by pars distales (pDs) taken from stressed trout. At lower concentrations (10 pmol/l) the peptide inhibited CRF-41-induced secretion of ACTH by pDs removed from unstressed trout, while at higher concentrations (10 nmol/l) it reduced the corticotrophic response of rat pituitary tissue to CRF-41.
Pineal denervation by cervical sympathetic ganglionectomy suppresses the role of photoperiod on pregnancy or pseudopregnancy, body weight and moulting periods in the mink (Mustela vison)
Authors: Martinet L. , Allain D. , Chabi Y. 
Published: December 2008

ABSTRACT
In mink, termination of the delayed implantation period, following reactivation of the corpora lutea, and onset of the spring moult are associated with a rise in prolactin secretion triggered by increasing daylength, while decreasing daylength induces the autumn moult. To establish whether suppression of the function of the pineal rendered the mink unresponsive to daylength changes, the superior cervical ganglion was removed bilaterally 2–4 weeks before mating. Intact and operated females were then left outdoors or were put under a lighting regime of either 15 h light: 9 h darkness (15L: 9D) or 8L: 16D. In July, at the end of the spring moult, the 15L: 9D lighting regime was changed to one of 8L: 16D. Under artificial photoperiods ganglionectomy suppressed the stimulatory role of long days and the inhibitory role of short days on prolactin secretion, and consequently on progesterone secretion and spring moult. Neither was the autumn moult, induced early in intact females by the change to a short photoperiod, advanced in ganglionectomized females, showing that the latter were unresponsive to the artificial modification of the photoperiod. However, in animals kept outdoors, prolactin and progesterone secretion and spring moult were not changed by ganglionectomy. Increase in body weight and autumn moult were only slightly delayed by the operation suggesting that other environmental factors had replaced the synchronizing effect of the daylength changes. Alternatively the desynchronization between intact females responsive to photoperiodism and those rendered unresponsive may be too slow to be observed soon after ganglionectomy.
J. Endocr. (1985) 107, 31–39
Effects of hyperprolactinaemia on reproduction in male mice
Authors: Nonomura M. , Hoshino K. , Harigaya T. , Hashimoto H. , Yoshida O. 
Published: December 2008

ABSTRACT
Hyperprolactinaemia induced by pituitary isografts in male host mice was confirmed by radioimmunoassay, but plasma testosterone levels determined by radioimmunoassay in these mice showed no changes. Immunoenzyme electron microscopic observations revealed large spherical-shaped immunoreactive prolactin granules in pituitary grafts in male hosts, regardless of the sex of the donor mice, indicating the disappearance of sexual dimorphism in prolactin-producing cells in hyperprolactinaemic mice. In hyperprolactinaemic host mice the male accessory sex glands, particularly the seminal vesicle and the ventral prostate, exhibited considerable proliferation and significant increase in weight. These phenomena do not seem to be mediated by the increased action of testosterone. Such biological effects in host mice were much greater when the donor was female rather than male, and were more noticeable in C57BL mice than in C3H mice.
J. Endocr. (1985) 107, 71–76
Prolactin and calcium metabolism in pregnant ewes
Authors: Barlet J. -P. 
Published: December 2008

ABSTRACT
The effect of ovine prolactin on intestinal Ca absorption and placental Ca transfer was studied in pregnant ewes. Six groups of five animals bearing a single fetus were used and injected s.c. daily between days 121 and 135. The first group was given 0·1 μg ovine prolactin/kg body wt per day, the second 0·1 μg ovine prolactin/kg body wt per day plus 0·1 μg 1α-hydroxycholecalciferol (1α-OH-D3)/kg body wt per day, the third 0 ·1 μg ovine prolactin/kg body wt per day plus 0·20 units calcitonin/kg body wt per day, the fourth 2 μg bromocriptine/kg body wt per day, the fifth 2 μg bromocriptine/kg body wt per day plus 0·1 μg ovine prolactin/kg body wt per day, and the sixth were controls injected with vehicle alone. The intestinal Ca absorption was measured on a duodenal loop tied off in vivo on day 136 and placental Ca transfer was evaluated between days 129 and 136. Ovine prolactin stimulated both intestinal Ca absorption and placental Ca transfer; these effects were further increased by 1α-OH-D3. Calcitonin had no effect on ovine prolactin-stimulated intestinal Ca absorption, but blunted the influence of ovine prolactin on Ca placental transfer. Bromocriptine decreased both intestinal Ca absorption and Ca placental transfer but these effects of bromocriptine were overcome by simultaneous injection of ovine prolactin.
J. Endocr. (1985) 107, 171–175
Progestin receptor in the thymus of ovariectomized immature rats
Authors: Fujii-Hanamoto H. , Seiki K. , Sakabe K. , Ogawa H. 
Published: December 2008

ABSTRACT
By using the synthetic progestin promegestone (R5020), the location and characteristics of progestin receptors in the thymic cytosols from immature ovariectomized oestrogen-treated rats were determined. Tritiated promegestone bound to the cytosol with high affinity (dissociation constant (Kd) = 2·0± 0·3 nmol/l; promegestone > progesterone > oestradiol > corticosterone ≃testosterone) and low capacity (number of binding sites (Bmax) = 143·0 ±13·5fmol/mg protein). These values were appropriate for progestin receptors. However, an extremely high dose of dexamethasone (10 μmol/l; 1000-fold excess over [3H]promegestone) slightly inhibited the specific binding. Progestin receptors were predominantly located in the reticuloepithelial (RE)-cell fraction, with few in the thymocyte T-cell fraction. The receptor level was raised (24·9 ± 11·3 (s.e.m.) to 143·0 ± 13·5 fmol/mg protein) with increased doses of oestrogen (0–30 μg) administered in vivo. Using sucrose density gradient ultra-centrifugation it was found that the thymic progestin receptor had a sedimentation coefficient of 9 S under low-salt conditions. These results clearly suggest that the thymus of the immature female rat contains a specific progestin receptor which is mainly located in the RE cells.
J. Endocr. (1985) 107, 223–229
Effect of stress administered during pregnancy on the development of fetal testes and their subsequent function in the adult rat
Authors: Pollard I. , Dyer S. L. 
Published: December 2008

ABSTRACT
When maternal stress, containing a large anxiety component, was administered during pregnancy there was a significant decrease in 3β-hydroxysteroid dehydrogenase (3β-HSD) activity in the fetal testis from days 16 to 20 of gestation, but not at birth nor in the first week after birth. However, persistent effects were found in adult males of 90 days of age. Basal testosterone concentrations in both plasma and testes and testicular 3β-HSD activity were significantly lower whilst basal plasma progesterone concentrations were significantly higher in the stressed group. When the stressed offspring were subjected to short-term stress (one session), their plasma testosterone concentration was significantly below that of the controls. It is suggested that suppressed gonadotrophin secretion during critical periods of development alters fetal testicular function, and that raised circulating levels of stress-induced hormones such as β-endorphin may be responsible for changes in gonadotrophin secretion.
J. Endocr. (1985) 107, 241–245
Electrical responses of cultured thyroid cells to serotonin
Authors: McGrath P. A. , Bourke J. R. , Huxham G. J. , Manley S. W. 
Published: December 2008

ABSTRACT
Cultured porcine thyroid cells, maintained in the differentiated state by dibutyryl cyclic AMP, responded to serotonin (5-HT; 10 nmol/l to 1 μmol/l) with a depolarization of the membrane potential, but did not respond to histamine (100 μmol/l) or dopamine (1 μmol/l). The resting membrane potential of these cells was about − 71 mV, maximal concentrations of 5-HT (1 μmol/l) inducing a depolarization to approximately −53 mV. Methysergide or phenoxybenzamine, but not propranolol, abolished the response to 5-HT. Sensitivity to 5-HT was reduced by previous exposure of cultures to TSH, the β-adrenoceptor agonist salbutamol or 5-HT itself.
J. Endocr. (1985) 107, 397–401