bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxytocin receptors in the oviduct during the oestrous cycle of the ewe
Authors: Ayad V. J. , McGoff S. A. , Wathes D. C. 
Published: December 2008

ABSTRACT
The presence of oxytocin receptors in ovine oviduct has been investigated. High-affinity binding sites for [3H]oxytocin were detected in crude membrane fractions prepared from the oviducts of ewes killed during the oestrous period. The dissociation constant calculated for these sites in competition studies was 1·7 nmol/l. Similar dissociation constants were calculated for [Arg8]-vasopressin and the oxytocin-specific agonists [Gly7]-oxytocin and [Thr4, Gly7]-oxytocin, indicating that these sites represent oxytocin receptors. At least one additional site of lower affinity and undetermined identity was present.
The relative concentration of oxytocin-binding sites in preparations of oviduct membranes were estimated in ewes killed at different stages of the oestrous cycle using a single concentration of [3H]oxytocin. Binding was low during the luteal phase of the cycle but increased to a maximum at oestrus (77·7 fmol/mg protein). Binding fell after ovulation, reaching what appeared to be basal concentrations by the early luteal stage of the cycle. Binding to oviductal membranes from prepubertal, anoestrous and pregnant ewes was also low, but in anoestrous animals which had been treated with progesterone and oestrogen it was similar to values measured in ewes at oestrus. These results are consistent with the existence of oviductal oxytocin receptors which are regulated by ovarian steroids.
We conclude that oxytocin receptors are present in the oviduct of the ewe around the time of ovulation. The significance of oxytocin to events taking place in the oviduct at this time remains to be determined.
Journal of Endocrinology (1990) 124, 353–359
Corticotrophin-releasing peptides in rat hypophysial portal blood after paraventricular lesions: a marked reduction in the concentration of corticotrophin-releasing factor-41, but no change in vasopressin
Authors: Antoni F. A. , Fink G. , Sheward W. J. 
Published: December 2008

ABSTRACT
Previous data show that corticotrophin-releasing factor-41 (CRF-41), arginine vasopressin (AVP) and oxytocin are released into hypophysial portal blood. It has been presumed that the CRF-41 originates mainly from parvicellular neurones of the paraventricular nuclei (PVN); however, AVP and oxytocin could also be derived as a consequence of preterminal release from magnocellular projections to the neurohypophysis. The latter has been suggested to be the case for AVP as assessed by studies of the median eminence in vitro. Here we have investigated the source of CRF-41, AVP and oxytocin in hypophysial portal blood of adult male Wistar rats 8–10 days after surgical lesioning of the PVN. In PVN-lesioned animals the output of CRF-41 into hypophysial portal blood was reduced by about 90%, and that of oxytocin by about 40%: however, the output of AVP into portal blood was reduced only by about 10%. The release of AVP into portal blood increased after adrenalectomy; this increased release could be returned to normal by treatment with dexamethasone. No change of AVP release occurred after adrenalectomy in animals in which the PVN had been lesioned. These results show (i) that most of the CRF-41 released into hypophysial portal blood is derived from the PVN, (ii) that in PVN-lesioned animals AVP and oxytocin release remains at near normal or 60% of normal respectively, suggesting that a substantial amount of both neuropeptides in portal blood is derived as a consequence of preterminal release from supraoptic nuclei projections in the median eminence, and (iii) that glucocorticoid feedback inhibition of AVP release is exerted at the level of the PVN.
Journal of Endocrinology (1990) 125, 175–183
Sex differences in cytochrome P-450-dependent xenobiotic and steroid metabolism in the mature rainbow trout kidney
Authors: Andersson T. 
Published: December 2008

ABSTRACT
The rainbow trout kidney during the late reproductive stages was found to exhibit a profound sex-related difference in its capacity to metabolize both xenobiotic model substrates and endogenous steroids. The cytochrome P-450 content of trunk kidney microsomes was 28-fold higher in males than in females. In trunk kidney microsomes, the dealkylation of various 7-alkoxycoumarins was 22- to 38-fold higher in males than in females, whereas ethylmorphine-N-demethylase (EMND) and 7-ethoxyresorufin-O-deethylase (EROD) activities were only slightly higher in males than in females. In contrast to the alkoxycoumarin- and EROD activities, the EMND activity showed considerable activity in the head kidney microsomes and the level was found to be higher in females than in males. Progesterone and androstenedione 16- and 6β-hydroxylase activities were present mainly in the male trunk kidney microsomes. On the contrary, the oestradiol 2-hydroxylase was distributed along the whole kidney and showed a 2·8-fold higher activity in the female head kidney than in the male head kidney. The catalytic analysis indicated a differential regulation of trout renal P-450 isoenzymes during sexual maturation. Furthermore, the data presented indicate that the high level of the hemoprotein in male trunk kidney was not a general increased level of the protein, but rather an increase of certain cytochrome P-450 isoenzymes.
Journal of Endocrinology (1990) 126, 9–16
Mutant gene-induced disorders of structure, function and thyroglobulin synthesis in congenital goitre (cog/cog) in mice
Authors: Adkison L. R. , Taylor S. , Beamer W. G. 
Published: December 2008

ABSTRACT
We have investigated thyroid structure and function in mice homozygous for the chromosome 15 mutation, congenital goitre (cog). Abnormal thyroidal hypertrophy and reduced iodine uptake in cog/cog mice were observed as early as day 18 of gestation, corresponding to the onset of thyroid function. Growth continued unabated in mutants throughout the 10-month period of observation. By 2 months of age, thyroid cell hypertrophy obliterated nearly all follicular lumina in cog/cog glands and by 10 months mean mutant thyroid mass exceeded that of age-matched littermates. Twenty-fold serum concentrations of thyrotrophin were significantly increased at all ages examined. While wild type (+/+) and heterozygote (+/cog) mice are indistinguishable from each other, thyroids of homozygote mutants (cog/cog) and the +/cog type are easily discernible from thyroids of the +/+ type by microscopic and thyroglobulin (Tg) analyses.
Thyrofollicular cells of both cog/cog and +/cog genotypes contain large vesicles of accumulated, non-glycosylated proteinaceous material not observed in cells from +/+ mice. Autoradiography showed 125I was incorporated only into Tg within recognizable follicular lumina of thyroids from +/cog mice. Serum concentrations of tri-iodothyronine are depressed during development in cog/cog mice. Serum concentrations of thyroxine are depressed during postnatal development but increase progressively to normal concentrations by 10 months of age. Our analyses indicate that full size Tg is produced in thyroid cells from cog/cog mice, though in a greatly reduced quantity, and that Tgs which are several sizes smaller than normal are also produced in both homozygote and heterozygote thyroids. In addition, we observed altered electrophoretic mobilities of 19S Tg and either the absence or greatly reduced quantities of one reduced 12S Tg form. Tg mRNA is apparently normal size in the mutant. However, there is a five- to tenfold reduction in the amount of polyadenylated Tg mRNA available that correlates with the decreased amounts of full size Tg seen in the mutant. Collectively, these findings suggest that the compensatory goitre of cog/cog mice results from disordered processing of Tg mRNA transcribed from the cog mutant gene.
Journal of Endocrinology (1990) 126, 51–58
Inhibin, gonadotrophins and sex steroids in dogs with Sertoli cell tumours
Authors: Grootenhuis A. J. , van Sluijs F. J. , Klaij I. A. , Steenbergen J. , Timmerman M. A. , Bevers M. M. , Dieleman S. J. , de Jong F. H. 
Published: December 2008

ABSTRACT
Inhibin bioactivity and mRNA for inhibin subunits were measured in four dog Sertoli cell tumours and in the testes of five normal control dogs. The tumours contained increased levels of inhibin (P <0·05) and mRNA for the α and βB subunits when compared with controls, whereas the mRNA for the βA subunit was not detected in tumours or control testes. The inhibin bioactivity was associated with a 32 kDa molecule in both Sertoli cell tumours and normal dog testes; no higher molecular weight forms were found after sodium dodecyl sulphate-polyacrylamide gel electrophoresis.
Peripheral levels of immunoassayable inhibin in dogs with Sertoli cell tumours were higher than those in the controls (P = 0·01), indicating that it might be possible to use this parameter as a marker for Sertoli cell tumours. Other testicular tumours, however, might also secrete immunoactive inhibin. The increased inhibin concentrations are likely to be the cause of the suppressed peripheral levels of FSH (P <0·02). However, peripheral levels of LH (P <0·02) and testosterone (P <0·01) were also suppressed in the dogs with Sertoli cell tumours, whereas the concentrations of oestradiol in the peripheral plasma of both groups did not differ. Finally, i.v. injection of the LHRH agonist buserelin caused a significant increase in LH and testosterone in the control dogs, but not in the dogs with Sertoli cell tumours.
It was concluded that secretory products from the Sertoli cell tumours suppressed pituitary gonadotrophin secretion. It is unlikely that testosterone or oestradiol play a role in this respect. FSH may be suppressed by the high levels of inhibin in tumour-bearing dogs, but it remains unclear whether inhibin or another Sertoli cell product is responsible for the unresponsiveness of the pituitary gland to LHRH and the suppression of LH.
Journal of Endocrinology (1990) 127, 235–242
Thyroid hormones during development of a marsupial, the tammar wallaby, Macropus eugenii
Authors: Janssens P. A. , Grigg J. A. , Dove H. , Hulbert A. J. 
Published: December 2008

ABSTRACT
The levels of thyroid hormones in the plasma and the activities of 5′-deiodinase activity in liver and kidney were determined in the tammar wallaby, Macropus eugenii, from early pouch life to adulthood. The total concentration of plasma thyroxine (T4) was below 15 nmol/l before day 75 of pouch life, rose to about 75 nmol/l at day 160, and then decreased to about 12 nmol/l in the adult. The total concentration of plasma tri-iodothyronine (T3) was below 0·4 nmol/l before day 120, increased to 3 nmol/l by about day 220 and then decreased to 1·0 nmol/l in adults. Concentrations of free T4 and free T3 followed a similar pattern but peaked at 45 and 160 pmol/l respectively. Concentrations of reverse T3 (rT3) were extremely variable, ranging from 0 to 1 nmol/l at day 100, and from 0 to > 2 nmol/l at day 180. After about day 230, rT3 levels fell rapidly and were below 0·3 nmol/l in adults. Liver and kidney 5′-deiodinase activities, which were undetectable before day 80, reached adult levels by day 220. Half-maximal activity of both these enzymes occurred at about day 205, mid-way between the peaks of T4 and T3. These findings suggest that the systems supporting synthesis and release of hormones from the thyroid gland are probably mature by about day 160 of pouch life in the tammar, while peripheral deiodinase activity, which is a major factor in the production of T3 in the plasma, matures by about day 220. These events thus precede the development of physiological independence of the young tammar from its mother.
Journal of Endocrinology (1990) 127, 427–436
Applicability of the product isolation and the radiometric aromatase assays for the measurement of low levels of aromatase: lack of aromatase activity in the human endometrium
Authors: Prefontaine M. , Shih C. , Pan C. C. , Bhavnani B. R. 
Published: December 2008

ABSTRACT
The purpose of this investigation was to assess the applicability of two well established procedures: (i) the product isolation assay and (ii) the radiometric 3H2O assay for the determination of very low levels of aromatase activity. The methods were validated and used to assess the capacity of normal and neoplastic human endometrium to synthesize oestrogens from androgens. Using the product isolation assay, various specimens (n = 27) of normal and neoplastic endometrium were incubated with [1,2,6,7-3H]testosterone either by a standard incubation procedure or by a superfusion technique. Following the incubation, carrier oestrone and oestradiol or [14C]oestrone and [14C]oestradiol were added, and the oestrogens were isolated and purified by paper chromatography and high-performance liquid chromatography. The radiochemical purity of oestrone and oestradiol was checked by the isotope dilution technique. In all samples, the 3H associated with oestrone and oestradiol failed to recrystallize as oestrone and oestradiol. No radioactivity was detectable in the oestrone and oestradiol crystals after acetylation. Similarly, 16 endometrial samples were tested for aromatase activity by the 3H2O release assay using [1β-3H]androstenedione as substrate. The results indicate that 3H2O was indeed released during these incubations, but this activity could not be inhibited by the aromatase inhibitor 4-hydroxyandrostenedione, by excess substrate or by heat inactivation of the tissue. Furthermore, the release of 3H2O from [1β-3H]androstenedione under the incubation conditions used (Dulbecco's modified Eagle's medium or RPMI-1640 containing fetal bovine serum and NADPH) also occurred in the absence of any tissue. This activity was not inhibited by 4-hydroxyandrostenedione nor by excess substrate. The results demonstrate that the human endometrium does not contain detectable levels of aromatase activity and that the radiometric assay can give rise to false-positive results if used for detection of very low levels of aromatase activity.
Journal of Endocrinology (1990) 127, 539–551
EVIDENCE FOR EXTENDED MAINTENANCE OF THE CORPUS LUTEUM BY UTERINE INFUSION OF A RECOMBINANT TROPHOBLAST α-INTERFERON (TROPHOBLASTIN) IN SHEEP
Authors: Martal J. , Degryse E. , Charpigny G. , Assal N. , Reinaud P. , Charlier M. , Gaye P. , Lecocq J.P. 
Published: December 2008

ABSTRACT
Ovine trophoblastin (oTP) is a natural interferon of the class-II interferon-α subfamily. Recombinant ovine trophoblastin (r.oTP), produced by genetic engineering, was purified by anion-exchange HPLC. The product exhibited a high degree of homogeneity (>98%), and similar immunological cross reaction and antiviral activity to natural oTP. Antiluteolytic activity of r.oTP was established by intrauterine injection in two groups of cyclic recipient ewes. Control group A included 10 ewes which received sterile BSA in saline twice daily for 8 days (from day 10-12 of oestrous cycle). Experimental group B included 17 ewes which received 80 μg (4 ewes), 170 μg (8 ewes) or 340 μg (5 ewes) r.oTP daily for 8 days. Maintenance of functional corpora lutea for 1 month or more was observed in 4 out of 5 ewes which received high doses of r.oTP. These results indicate that oTP alone extends luteal secretory activity.
Progesterone and 5β-pregnanediol production by isolated fetal placental binucleate cells from sheep and goats
Authors: Wango E. O. , Heap R. B. , Wooding F. B. P. 
Published: December 2008

ABSTRACT
Enzymic dispersion and density gradient separation were used for the isolation of enriched populations (60–90%) of cells from the corpus luteum, placenta and peripheral blood of pregnant sheep and goats. Analysis of the steroids produced from radioactive pregnenolone demonstrated that placental binucleate cells can produce progesterone and 5β-pregnanediol whereas white blood cells were relatively inactive. Thus, sheep binucleate cells converted pregnenolone predominantly to progesterone as did sheep luteal cells. However, goat binucleate cells produced 5β-pregnanediol as the major metabolite, which is consistent with its production in vivo during pregnancy. Production of progesterone (sheep) or 5β-pregnanediol (goat) by binucleate cells was shown to be proportional to the number and viability of the cells. In contrast with the binucleate cells there was no evidence that trophectodermal uninucleate cells play a significant role in placental progesterone or 5β-pregnanediol synthesis in either species.
Journal of Endocrinology (1991) 129, 283–289
Steroidogenesis during postnatal development in the mouse ovary
Authors: Mannan M. A. , O'Shaughnessy P. J. 
Published: December 2008

ABSTRACT
In the mouse, follicular formation and development is largely postnatal. Changes in ovarian steroidogenesis during early postnatal life are likely, therefore, to reflect changes in follicular activity during early folliculogenesis. In this study, basal progesterone and androstenedione production and responsiveness to gonadotrophins, dibutyryl cyclic AMP (dbcAMP) and 22R-hydroxycholesterol have been measured following short-term in-vitro incubations of ovaries from mice aged 1, 3, 5, 7, 10 or 15 days. On the day of birth (day 1), basal and gonadotrophin-stimulated progesterone and androstenedione production were undectectable although a response to dbcAMP and a low level of cholesterol side-chain cleavage (CSCC) activity (measured using 22R-hydroxycholesterol) were present. On day 3 progesterone and androstenedione production were undetectable under all conditions. On day 5 only a low level of CSCC activity was detectable but on day 7 there was an increase in ovarian steroid production. Basal progesterone and androstenedione were detectable and LH, but not FSH, increased the production of both steroids. These changes were associated with a marked increase of more than 80-fold in CSCC activity. Basal steroid output increased from days 7 to 15 and LH continued to stimulate progesterone accumulation although no effect on androstenedione was seen. Addition of FSH had no effect on steroidogenesis on day 10 but significantly increased progesterone production on day 15. Ovaries from the mice used in these studies contained primordial follicles and stromal tissue on day 1. By day 5 primary and secondary follicles were present and the major increase in steroid production between days 5 and 7 was associated with an increase in secondary follicles and increased differentiation of the thecal tissue. These results show that there is a major increase in ovarian steroidogenesis at day 7 in the mouse and suggest that during folliculogenesis significant gonadotrophin-sensitive steroidogenesis may first be seen in the thecal tissue of the secondary follicle.
Journal of Endocrinology (1991) 130, 101–106
Platelet-activating factor stimulates the release of atrial natriuretic factor from the rat heart
Authors: Rayner T. E. , Menadue M. F. , Oliver J. R. 
Published: December 2008

ABSTRACT
Atrial natriuretic factor (α-ANF(99–126); ANF) is released from atrial cells following atrial distension, myocardial infarction and periods of ischaemic or tachyarrhythmias. In this report we demonstrate that platelet-activating factor (PAF) stimulates ANF release from the isolated perfused rat heart and following i.v. injection to conscious unrestrained rats. ANF release peaked at 145% above baseline following injection of 2·5 nmol PAF into the isolated heart while administration of 2 nmol in vivo produced a 135% increase in plasma ANF levels. The PAF receptor antagonist BN52021 (10 μmol/l) attenuated this stimulated release, with the results suggesting a role for PAF in ANF secretion following release from damaged myocardium or as a humoral factor originating from the kidney.
Journal of Endocrinology (1991) 130, 281–288
Role of the placenta in the control of the ante-partum surge of prolactin in the rat
Authors: Grattan D. R. , Averill R. L. W. 
Published: December 2008

ABSTRACT
A nocturnal surge of prolactin secretion occurs in the dark period preceding parturition in the rat. The aim of this study was to examine the role of the placenta in the control of this prolactin surge. Plasma prolactin and progesterone were measured by radioimmunoassay in serial blood samples collected after surgical removal of conceptuses during late pregnancy, and after intracerebroventricular (i.c.v.) injection of placental lactogen (PL) before the prolactin surge.
In intact control animals, prolactin secretion remained low until a nocturnal surge of secretion occurred in the dark period preceding parturition, peaking at 269±51 (s.e.m.) μg/l at 03.00 h on day 21. Progesterone levels fell from > 200 nmol/l on day 19 to <40 nmol/l by 12.00 h on day 20 of pregnancy. PL levels during late pregnancy were modified by partial or complete removal of conceptuses at 10.00 h on day 19 of pregnancy. Removal of all but one or two conceptuses did not change the normal pattern of prolactin or progesterone secretion. Removal of all conceptuses, however, induced a large nocturnal surge of prolactin secretion, peaking at 211·7±78 μg/l at 03.00 h on day 20, 24 h earlier than the surge in intact animals. Progesterone levels after removal of all conceptuses fell to <40 nmol/l by 23.00 h on day 19, approximately 12 h before the decline in intact animals. Maintenance of increased progesterone levels after conceptus removal using silicone tubing implants significantly (P <0·05) reduced the peak of the premature prolactin surge to 79·7 ±18 μg/l at 05.00 h on day 20. To determine whether PL could act at the hypothalamic level to inhibit the prolactin surge, human PL was injected into the lateral ventricle. PL injected i.c.v. at 17.00 h on day 7 of pregnancy completely abolished both the expected diurnal and nocturnal prolactin surges in the subsequent 24 h. By contrast, the same treatment on day 20 of pregnancy had no effect on the ante-partum prolactin surge.
These results demonstrate two changes in the mechanisms controlling prolactin secretion on the last day of pregnancy compared with prolactin secretion during early pregnancy. First, feedback inhibition of prolactin secretion by PL which occurs at mid-pregnancy was not functional on the last day of pregnancy. Secondly, progesterone which promotes the nocturnal prolactin surges of early pregnancy, inhibited prolactin secretion during late pregnancy.
Journal of Endocrinology (1991) 130, 401–407