bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic antagonists of the myometrial response to vasopressin and oxytocin
Authors: Melin P. , Trojnar J. , Johansson B. , Vilhardt H. , Åkerlund M. 
Published: December 2008

ABSTRACT
With the aim of developing inhibitors of vasopressin-and oxytocin-induced uterine activity, 17 analogues of 1-deamino-oxytocin were synthesized by the solid-phase method. Modifications were made at positions 2, O-methyltyrosine (Tyr(OMe)) and O-ethyltyrosine (Tyr(OEt)),d-Tyr,d-Tyr(OEt),d-Trp; 4, Val,Thr and 8, Orn,Cit,Arg,d-Arg.
The analogues were tested for antiuterotonic activity in vitro and in vivo in the rat and in vitro on myometrial strips from non-pregnant women and pregnant women at term. Their selectivity was also investigated in blood pressure and antidiuretic bioassays in rats. Results were compared with those from an original antiuterotonic analogue 1-deamino-2-Tyr(OEt)-oxytocin (d(OEt)-oxytocin). In the rat in vitro and in vivo all analogues possessed higher antiuterotonic activity than d(OEt)-oxytocin. The negative logarithm of the molar concentration of the antagonist which reduced the effect of a dose of agonist to that of half the dose (pA2) was between 7·6 and 8·9 for all the new inhibitors compared with 7·2 for d(OEt)-oxytocin. The highest pA2 value was found for 1-deamino-2-Tyr(OMe)-8-Orn-oxytocin (8·9 ± 0·2, s.e.m.) and 1-deamino-2-Tyr(OEt)-4-Thr-8-Orn-oxytocin (8·9 ± 0·6). In myometrium from non-pregnant women the most potent peptide was 1-deamino-2-d-Tyr(OEt)-4-Th r-8-Orn-oxytocin (17·2 ± 2·0 times more potent that d(OEt)-oxytocin). In myometrium from pregnant women the inhibitory effects of the majority of the analogues were less pronounced. In the rat in vivo the most potent analogue 1-deamino-2-d-Trp-4-Val-8-Orn-oxytocin was 19·9 ± 2·5 times more active than d(OEt)-oxytocin. Exchanging l-tyrosine for the d form generally increased inhibitory activity as well as specificity of the analogues. Alkylation of the d-tyrosine residue did not appear to be necessary for inhibition. Substitution with d-tryptophan at position 2 gave analogues with high inhibitory potency in the rat in vitro and in vivo, but which exhibited weak effects in women in vitro. There was no correlation between the inhibitory effects on myometrium from non-pregnant and pregnant women nor between rat and human data. The high antiuterotonic activity of 1-deamino-2-d-Tyr(OEt)-4-Val-8-Orn-oxytocin and 1-deamino-2-d-Tyr(OEt)-4-Thr-8-Orn-oxytocin combined with low blood pressure and antidiuretic effects make these two analogues interesting for clinical studies.
J. Endocr. (1986) 111, 125–131
Methoxyindole production by the pineal gland appears to be dependent on the concentration of hydroxy precursors and their affinity for hydroxyindole-O-methyltransferase
Authors: Morton D. J. 
Published: December 2008

ABSTRACT
Various pineal gland indole metabolites were separated by thin-layer chromatography after organ culture with tritiated serotonin. The amounts of methoxyindoles produced were remarkably constant and female rats in oestrus appeared to produce greater amounts than male rats. The results show a correlation between methylation and the concentration and affinity of the various hydroxyindoles for hydroxyindole-O-methyltransferase.
J. Endocr. (1986) 111, 133–136
Corticotrophin-releasing factor in extra-hypothalamic brain of the mouse: demonstration by immunoassay and immunoneutralization of bioassayable activity
Authors: Nakane T. , Audhya T. , Hollander C. S. , Schlesinger D. H. , Kardos P. , Brown C. , Passarelli J. 
Published: December 2008

ABSTRACT
Corticotrophin-releasing factor (CRF) bioactivity has been described in the extra-hypothalamic brain, but its relationship to hypothalamic CRF has remained questionable. Of the seven regions of the mouse brain examined, highest concentrations of CRF-like immunoreactivity (CRF-LI) and bioassayable CRF activity were present in the median eminence and hypothalamus. However, substantial CRF-LI and bioassayable CRF activity were also seen in brain extracts from the amygdala, thalamus, frontal cortex, pons medulla and cerebellum. Bioactivity was largely neutralized by prior incubation with heat-inactivated antiserum to ovine CRF. These findings, in conjunction with previous immunocytochemical evidence, strongly suggest that a substance closely resembling hypothalamic CRF is present in the extrahypothalamic brain of the mouse.
J. Endocr. (1986) 111, 143–149
Blood levels of ionized calcium, inorganic phosphorus, 1,25-dihydroxycholecalciferol and gonadal hormones in hens laying hard-shelled or shell-less eggs
Authors: Nys Y. , N'Guyen T. M. , Williams J. , Etches R. J. 
Published: December 2008

ABSTRACT
The production of shell-less eggs was induced in hens to measure the effects of the high demands made by shell formation on the blood minerals and hormones whose concentrations change during egg formation. In control hens laying hard-shelled eggs, the concentration of ionized calcium in plasma decreased at the onset of shell formation, but no change was found in hens laying shell-less eggs. Total calcium concentrations in plasma decreased slightly throughout the ovulation cycle in both groups. Concentrations of inorganic phosphorus in the plasma were increased in the control group during the period of shell formation and decreased when calcification was suppressed. Finally, the concentrations of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) in plasma were significantly increased 16 and 20 h following an ovulation compared with 4 h after ovulation, or compared with the concentrations observed in hens laying shell-less eggs. The variations in the plasma concentrations of ionized calcium, inorganic phosphorus and 1,25-(OH)2D3 associated with egg formation were therefore absent in hens laying shell-less eggs demonstrating their direct link with shell calcification. On the other hand, suppression of shell production had no influence on the changes in the plasma concentrations of progesterone, oestradiol and testosterone which are associated with the normal ovulatory cycle. It is concluded that the increases in intestinal and uterine calcium transport and in 1,25-(OH)2D3 production which occur at the onset of egg production in hens are mainly controlled by factors involved in maintaining calcium homeostasis rather than by gonadal hormones.
J. Endocr. (1986) 111, 151–157
Dopaminergic inhibition of tyrosinase activity in hair follicular melanocytes of the mouse
Authors: Burchill S. A. , Thody A. J. 
Published: December 2008

ABSTRACT
Bromocriptine, a dopamine agonist that blocks the secretion of MSH, inhibits melanogenesis in the hair follicular melanocytes of pubertal C3H–HeA*vy mice. However, since this effect cannot be explained by a reduction in circulating α-MSH, we have examined the possibility that dopaminergic mechanisms may have a direct inhibitory effect on these melanocytes.
Bromocriptine decreased tyrosinase activity in skin explants from 30- to 35-day-old mice that were growing dark hair. This decrease in tyrosinase activity was blocked by dopamine receptor antagonists, haloperidol or spiperone. The specific D2 agonist LY 171555 also inhibited tyrosinase activity in the skin explants in a dose-related manner and the effect was blocked by sulpiride, a D2-receptor antagonist. Neither bromocriptine nor LY 171555 had any effect on tyrosinase activity in skin explants taken from adult mice that were growing yellow hair. The D1-receptor agonist SKF 38393 had no effect on tyrosinase activity in skin explants from either group of mice.
The present results support the idea that dopamine D2-receptor agonists have a direct inhibitory effect upon tyrosinase activity of hair follicular melanocytes of the C3H–HeA*vy mouse. However, this effect was confined to periods of dark hair growth when the melanocytes produce eumelanin. The D2 agonists were ineffective in reducing tyrosinase activity during adult life when the melanocytes produce predominantly phaeomelanin. This suggests that different control mechanisms may operate in the hair follicular melanocytes during periods of eumelanin and phaeomelanin synthesis.
J. Endocr. (1986) 111, 233–237
Cholinergic agonist and antagonist drugs modulate the growth hormone response to growth hormone-releasing hormone in the rat: evidence for mediation by somatostatin
Authors: Locatelli V. , Torsello A. , Redaelli M. , Ghigo E. , Massara F. , Müller E. E. 
Published: December 2008

ABSTRACT
Recently, data have been presented showing that muscarinic cholinergic agonists or antagonists can modulate, in opposite ways, GH-releasing hormone (GHRH)-induced GH release in man. The aim of the present study was, first, to confirm these findings in the rat and, secondly, if confirmed, to investigate the mechanism(s) subserving the effect of cholinergic drugs.
In adult male rats bearing chronic indwelling atrial cannulae, pretreatment with the cholinergic antagonists pirenzepine (0·5 mg/kg, i.v.) or atropine (0·5 mg/kg, i.v.) significantly reduced the rise in plasma GH induced by GHRH (2 μg/kg, i.v.), while pretreatment with the cholinergic agonist pilocarpine (3 mg/kg, i.v.) potentiated it. In rats with hypothalamic somatostatin (SRIF) depletion, i.e. rats with anterolateral deafferentation of the mediobasal hypothalamus or rats treated with cysteamine, the modulatory action of cholinergic drugs on the neuroendocrine effect of GHRH was completely lacking. In these two experimental models, an antiserum raised against SRIF failed to elicit a rise in plasma GH and measurement of hypothalamic SRIF content revealed a clear-cut reduction of the neuropeptide. Atropine (1 μmol/l) and pilocarpine (1 μmol/l), added to pituitary cells in vitro, failed to alter GHRH-induced GH release. The present results indicate that muscarinic cholinergic agonists and antagonists modulate GHRH-induced GH release in the rat and suggest that the effect of cholinergic modulation takes place through SRIF.
J. Endocr. (1986) 111, 271–278
Changes in FSH and the pulsatile secretion of LH during treatment of ewes with bovine follicular fluid throughout the luteal phase of the oestrous cycle
Authors: Wallace J. M. , McNeilly A. S. 
Published: December 2008

ABSTRACT
Treatment of Damline ewes with twice-daily i.v. injections of bovine follicular fluid during the luteal phase for 10 or 2 days before prostaglandin-induced luteolysis resulted in a delay in the onset of oestrous behaviour and a marginal increase in ovulation rate. During the treatment cycle, blood samples were withdrawn at 15-min intervals for 25 h from 08.00 h on days 1, 6 and 10 (day 0 = oestrus). At all three stages of the luteal phase, plasma FSH concentrations were suppressed relative to controls 3 h after the 09.00 h injection of follicular fluid and remained low until
06.00 h on the following day. In the 10-day treatment group LH pulse amplitude was significantly greater than that of controls on days 6 and 10. Pulse frequency remained high throughout treatment and was significantly higher relative to controls on day 10 despite normal progesterone levels. The results suggest that the higher pulsatile LH secretion during the luteal phase is due to reduced negative feedback effects of oestradiol occurring as a result of the follicular fluid-induced reduction in FSH.
J. Endocr. (1986) 111, 317–327
Regression of redundant lactotrophs in rat pituitary gland after cessation of lactation
Authors: Haggi E. S. , Torres A. I. , Maldonado C. A. , Aoki A. 
Published: December 2008

ABSTRACT
Regressive changes occurring in the pituitary gland of the rat after removal of litters were studied. Pituitary glands of lactating rats were characterized by the presence of numerous hypertrophied lactotrophs. Interruption of lactation caused a blockade of prolactin synthesis and secretion, followed by degeneration of lactotrophs. Morphometric analysis of pituitary glands revealed that lactotrophs accounted for about 50% of the total hypophysial cell count in lactating rats. This percentage decreased progressively and reached pre-pregnant levels 7 days after removal of litters; the decrease was inversely correlated with an increase in the number of degenerating lactotrophs which comprised 30% of all lactotrophs 72 h after removal of litters. The morphological changes found in lactotrophs were closely related to changes in the prolactin content of serum and the pituitary gland. Regression of lactotrophs appeared to be the most important cause inducing the reversal of hypophysial lactotrophic activity to pre-pregnant conditions.
J. Endocr. (1986) 111, 367–373
Met-enkephalin stimulates secretion of ACTH in sheep
Authors: Wang X.-M. , Coghlan J. P. , Congiu M. , Scoggins B. A. , Wintour E. M. 
Published: December 2008

ABSTRACT
The ability of opioid peptides to affect plasma immunoreactive ACTH concentrations was examined in conscious sheep. Plasma concentrations of ACTH were significantly increased by an i.v. infusion of Met-enkephalin and its analogue (FK-33824). There was a dose-dependent increase in plasma concentrations of ACTH with a graded administration of FK-33824. The combined effect of Met-enkephalin and ovine corticotrophin-releasing factor (oCRF) or FK-33824 and oCRF on plasma concentrations of ACTH was greater than the effect of each peptide when given individually. This study demonstrates that Met-enkephalin and its analogue stimulate ACTH release in sheep.
J. Endocr. (1986) 111, 463–467
Characterization by high-performance liquid chromatography of circulating growth hormone-releasing factors in normal subjects
Authors: Penny E. S. , Sopwith A. M. , Patience R. L. , Wass J. A. H. , Besser G. M. , Rees L. H. 
Published: December 2008

ABSTRACT
Four forms of circulating immunoreactive human GH-releasing factor (ir-hGRF) have been identified in each of four normal subjects, with a mean increase in total ir-hGRF of twofold over basal levels following a mixed meal. Plasma samples (200 ml) from each individual were subjected to large-scale Vycor extraction with initial purification by high-performance liquid chromatography on a reversed-phase C18 column, followed by analytical separation of the ir-hGRF components using a C3 wide-pore reversed-phase column, and subsequent radioimmunoassay of the fractions. The mean recovery of total ir-hGRF from the plasma (fasted and non-fasted) was 76±16% (2×s.e.m.). Analytical separation of the ir-hGRF revealed four components which co-eluted with synthetic hGRF-37, hGRF-40 and hGRF-44, and a peak eluting between hGRF-40 and -44 which may represent hGRF-42. The hGRF-40 was shown to be the predominant circulating molecular form in the fasted state in each subject, and in three out of four subjects following a mixed meal. The hGRF-44 showed the greatest percentage increase over basal in all four individuals.
J. Endocr. (1986) 111, 507–511
Differentiation of granulated metrial gland cells in ovariectomized mice given ovarian hormones
Authors: Stewart I. 
Published: December 2008

ABSTRACT
A study has been made of the differentiation of granulated metrial gland (GMG) cells in ovariectomized mice given progesterone and oestradiol at a time equivalent to the first 6 days of pregnancy. By varying the hormone regime, it was shown that progesterone is the ovarian hormone likely to be involved in stimulating GMG cell differentiation in the early pregnant uterus. Progesterone, however, failed to maintain, or allow further differentiation, of GMG cells during stages equivalent to the early post-implantation period, suggesting that the progesterone is not directly stimulating this cell population. The hypothesis that the differentiation and maintenance of GMG cells is under the control of activated stromal cells in the preimplantation period is supported by these results.
J. Endocr. (1987) 112, 23–26
Blockade of the final phase of ovulation has no effect on the post-ovulatory surge of serum FSH in the rabbit
Authors: Bolet G. , Meunier M. , Blanc M.R. , Martinet L. , Poirier J.C. 
Published: December 2008

ABSTRACT
Mating induces a surge of both LH and FSH in the blood of female rabbits, followed 10–12 h later by a surge of FSH only, which begins at the time of ovulation. We have studied the effect of suppression of ovulation on the post-ovulatory surge of FSH. In the first experiment, follicular fluid and oocytes were withdrawn from the largest follicles 8 h after coitus. In the second experiment, ovulation was inhibited by injecting the rabbits with 25 mg indomethacin/kg body weight 7·5 h after mating. Levels of serum FSH and LH were measured for 24-48 h after mating. Control rabbits ovulated normally in both experiments. The treatments did not significantly affect the levels of serum FSH in either experiment, although the second surge of FSH was slightly higher after fluid had been aspirated from the preovulatory follicles. These observations show that the post-ovulatory surge of serum FSH is not dependent upon the completion of ovulation and that it is programmed before 7·5–8 h post coitum.
J. Endocr. (1987) 112, 57–61
Osmoregulatory actions of growth hormone in rainbow trout (Salmo gairdneri)
Authors: Bolton J. P. , Collie N. L. , Kawauchi H. , Hirano T. 
Published: December 2008

ABSTRACT
The seawater-adapting actions of GH, which are independent of growth, were studied in juvenile rainbow trout (Salmo gairdneri). Hormones examined were chum salmon (Oncorhynchus keta) GH (sGH) and prolactin (sPRL), and ovine GH (oGH). Plasma Na levels of freshwater-adapted fish peaked 24 h after transfer to 67% seawater and remained high for at least 48 h. Twenty-four hours after transfer, plasma Na levels were inversely correlated to body weight. In order to limit size and growth effects in all subsequent experiments, fish having a narrow range of body weights, fed a fixed diet, and injected with hormones over a short time-period were used. Plasma Na levels 24 h after transfer to 80% seawater were reduced significantly by sGH (0·25 and 2·5 μg/g) and oGH (2·5 μg/g) compared with saline injections, whereas sPRL (2·5 μg/g) had no significant effect. All the GH-treated fish had lower plasma Mg levels than controls; Ca levels were significantly reduced by the high dose of sGH. Salmon prolactin had no effect on concentrations of divalent ions. When the effects of a range of doses (0·01–1·25 μg/g) of sGH on plasma ion levels was tested, 0·25 μg/g was the most potent in reducing Na and Mg levels, while 1·25 μg/g alone reduced plasma Ca concentrations significantly. These studies show that the seawater-adapting actions of GH in trout are specific to that hormone and are not consequent to an increase in size.
J. Endocr. (1987) 112, 63–68
Effect of adrenaline on basal and ovine corticotrophin-releasing factor-stimulated ACTH secretion in man
Authors: Al-Damluji S. , Cunnah D. , Grossman A. , Perry L. , Ross G. , Coy D. , Rees L. H. , Besser G. M. 
Published: December 2008

ABSTRACT
Six normal male subjects were given, in single blind random order on six separate occasions, i.v. bolus doses of synthetic ovine corticotrophin-releasing factor-41 (oCRF-41; 25 and 50 μg) with and without adrenaline (3 μg/min) i.v. for 150 min, the adrenaline infusions alone and saline placebo. The adrenaline infusions resulted in plasma adrenaline concentrations of 4·33 ± 0·82 (s.e.m.) nmol/l and were associated with an increase in blood glucose, heart rate and systolic blood pressure and a reduction of diastolic blood pressure. Despite these evident biological effects at several sites, there was no stimulation of plasma ACTH or cortisol by adrenaline in comparison with the effect of saline, and no enhancement of the stimulatory effect of either dose of oCRF-41 on ACTH or cortisol secretion. The ACTH response to 50 μg oCRF-41 was greater than that to 25 μg, indicating that the 25 μg dose of oCRF-41 was sub-maximal and capable of further enhancement. As the plasma adrenaline concentrations during the adrenaline infusions reached the upper limit of the physiological range of plasma adrenaline in man, yet failed to enhance the ACTH or cortisol responses to a sub-maximal dose of oCRF-41, we conclude that circulating adrenaline neither exerts a direct stimulatory effect on pituitary corticotrophs nor enhances the effect of CRF under physiological circumstances. The adrenaline infusions attenuated the ACTH and cortisol responses to oCRF-41 and were associated with a transient reduction of basal concentrations of both hormones.
J. Endocr. (1987) 112, 145–150
Neuroendocrine studies in hyperprolactinaemic male mice
Authors: Bartke A. , Morgan W. W. , Clayton R. N. , Banerji T. K. , Brodie A. M. , Parkening T. A. , Collins T. J. 
Published: December 2008

ABSTRACT
In several species, including man and the rat, hyperprolactinaemia is associated with suppression of gonadotrophin release and male sexual behaviour. However, in the hyperprolactinaemic male mouse, plasma LH and FSH levels and copulatory behaviour are increased rather than suppressed. In an attempt to identify mechanism(s) which may be responsible for these effects of hyperprolactinaemia in the mouse, we have examined the effects of two ectopic pituitary isografts on several indices of hypothalamic and pituitary function in adult DBA/2J males. Animals with pituitary grafts had markedly increased plasma concentrations of prolactin, LH and FSH and enlarged seminal vesicles, whereas testicular and pituitary weights were not affected. Content of LHRH receptors and activity of aromatase in the pituitary, as well as dopamine-β-hydroxylase activity in the hypothalamus were nearly identical in pituitary-grafted and sham-operated males. Biosynthesis of dopamine and turnover of noradrenaline in the median eminence were significantly increased in grafted males. We suggest that the increase in the activity of hypothalamic noradrenergic neurones may mediate stimulatory action of hyperprolactinaemia on LH and FSH release in the mouse. Comparison of these results with those obtained previously in the rat suggests that species differences in the effects of prolactin on gonadotrophin release may be related to its divergent effects on noradrenaline turnover.
J. Endocr. (1987) 112, 215–220
Ethan-1,2-dimethanesulphonate reduces testicular oxytocin content and seminiferous tubule movements in the rat
Authors: Nicholson H. D. , Worley R. T. S. , Guldenaar S. E. F. , Pickering B. T. 
Published: December 2008

ABSTRACT
An oxytocin-like peptide is present in the interstitial cells of the testis, and testicular concentrations of oxytocin have been shown to increase seminiferous tubule movements in vitro. We have used the drug ethan-1,2-dimethanesulphonate (EDS), which depletes the Leydig cell population of the adult rat testis, to examine further the relationships between the Leydig cell, testicular oxytocin and tubular movements. Adult rats were injected i.p. with a single dose of EDS (75 mg/kg) or of vehicle (25% dimethyl sulphoxide). Histological study 3 and 10 days after treatment with EDS showed a reduction in the number of interstitial cells, and levels of oxytocin immunoreactivity were undetectable by radioimmunoassay. Immunostaining revealed very few oxytocin-reactive cells. Spontaneous contractile activity of the seminiferous tubules in vitro was also dramatically reduced, but could be restored by the addition of oxytocin to the medium. Four weeks after EDS treatment, the interstitial cells were similar to those in the control animals both in number and in immunostaining; immunoassayable oxytocin was present and tubular movements were normal. The EDS effect, seen at 3 and 10 days, was not altered by daily treatment with testosterone. However, repopulation of the testes with oxytocin-immunoreactive cells was not seen until 6 weeks in the testosterone-treated animals.
We suggest that the Leydig cells are the main source of oxytocin immunoreactivity in the testis and that this oxytocin is involved in modulating seminiferous tubule movements and the resultant sperm transport. The results also imply that testosterone does not play a major role in controlling tubular activity in the mature rat.
J. Endocr. (1987) 112, 311–316