bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation between LH secretion in castrated rats with cellular proliferation and synthesis of DNA in the anterior pituitary gland
Authors: Romano M. I. , Machiavelli G. A. , Pérez R. L. , Carricarte V. , Burdman J. A. 
Published: December 2008

ABSTRACT
The relationship between the release of LH and the synthesis of DNA was studied in the anterior pituitary gland of castrated rats. Cell types were characterized immunocytochemically. Castration significantly (P < 0·01) increased the concentration of LH in serum (1326%) and the incorporation of [3H]thymidine into pituitary DNA (72%). This was accompanied by an increment in the activity of the enzyme DNA polymerase-α (58%) and in the number of mitoses (from 2± 0·1/mm2 in intact rats to 21 ± 0·8/mm2 15 days after castration). Only 20% of the mitoses found in the pituitary gland of castrated rats were positively stained with the antiserum against the β-subunit of LH. The other 80% did not stain either with LH antiserum or with antisera against the other pituitary hormones. There was a significant (P < 0·01) increase in the number of LH cells in castrated rats (48%). All the changes produced in the anterior pituitary gland after castration were prevented by the administration of dihydrotestosterone. The results demonstrate that a stimulation of LH release is followed by an increase of DNA synthesis and cell proliferation of gonadotrophs in the anterior pituitary gland.
J. Endocr. (1984) 102, 13–18
Pattern of excretion of urinary steroid metabolites during the ovarian cycle and pregnancy in the marmoset monkey
Authors: Eastman S.-A. K. , Makawiti D. W. , Collins W. P. , Hodges J. K. 
Published: December 2008

ABSTRACT
Non-invasive methods for monitoring reproductive status based on the measurement of urinary steroid conjugates were examined. Levels of urinary oestrone-3-glucuronide, oestrone-3-sulphate, oestradiol glucuronide, oestradiol sulphate and pregnanediol-3α-glucuronide were determined during the ovarian cycle and pregnancy. Sequential hydrolysis showed oestradiol conjugates to be more abundant than oestrone conjugates. The levels of sulphates and glucuronides were similar in the follicular phase whereas sulphates predominated during the luteal phase and pregnancy. Although levels of oestrone-3-sulphate were two- to fourfold lower than those of oestradiol sulphate, measured after hydrolysis, the profiles throughout the cycle and pregnancy were similar. Levels of oestrone-3-sulphate, measured by direct assay, were below 1 μmol/mmol creatinine during the follicular phase, rising 3–4 days after ovulation to reach maximum values (2–8 μmol/mmol creatinine) in the mid-luteal phase. There was no consistent increase before ovulation. Levels during pregnancy rose gradually until days 70–90, after which there was no further increase (gestation length = 144 days). The pattern of pregnanediol-3α-glucuronide was similar to that of oestrone-3-sulphate during the ovarian cycle but levels did not increase during pregnancy. The patterns of excretion of oestrogen and progesterone metabolites were similar to the pattern of the circulating hormones during the ovarian cycle. Circulating and urinary hormone patterns were similar for oestrogens throughout pregnancy but pregnanediol-3α-glucuronide did not reflect progesterone secretion beyond day 70 of gestation.
J. Endocr. (1984) 102, 19–26
Hyperprolactinaemia abolishes sensitivity of stria terminalis neurones to testosterone
Authors: Kendrick K. M. , Dixson A. F. 
Published: December 2008

ABSTRACT
Hyperprolactinaemia was induced in castrated, testosterone-treated male rats using ectopic pituitary grafts under the kidney capsules. After 6 weeks the absolute refractory period of stria terminalis neurones in these animals did not differ significantly from long-term castrated rats (mean = 1·72 vs 1·69 ms) in spite of the presence of normal testosterone concentrations. Gonadally intact animals, and sham-operated castrated animals treated with testosterone, showed by comparison the characteristic significantly shorter absolute refractory period normally associated with testosterone stimulation (mean = 1·15 and 1·08 respectively). These results provide the first demonstration that hyperprolactinaemia can abolish central sensitivity to testosterone.
J. Endocr. (1984) 102, 109–113
Effects of synthetic mammalian thyrotrophin releasing hormone, somatostatin and dopamine on the secretion of prolactin and growth hormone from amphibian and reptilian pituitary glands incubated in vitro
Authors: Hall T. R. , Chadwick A. 
Published: December 2008

ABSTRACT
Pituitary glands of grassfrog (Rana pipiens), bullfrog (Rana catesbeiana), clawed toad (Xenopus laevis) and two species of terrapin (Chrysemys picta and Pseudemys scripta) were incubated in medium containing hypothalamic extract (HE), thyrotrophin releasing hormone (TRH), somatostatin, dopamine, or combinations of these treatments. Prolactin and GH concentrations in the medium were determined by densitometry after polyacrylamide-gel electrophoretic separation. Hypothalamic extract stimulated secretion of both hormones in all species tested. Thyrotrophin releasing hormone stimulated secretion of prolactin and GH, showing a biphasic pattern of response. Dopamine had little effect alone, but inhibited HE-and TRH-stimulated release of prolactin, but not GH, in both amphibia and reptiles. Somatostatin by itself had no apparent effect on release of hormones, but it inhibited HE- and TRH-stimulated release of GH from both amphibian and reptilian pituitary glands. These results indicate that factors affecting mammals and birds also interact in the regulation of secretion of prolactin and GH in lower vertebrate species.
J. Endocr. (1984) 102, 175–180
Analysis of activated androgen receptors in rat brain and anterior pituitary and ventral prostate glands: nuclear binding and RNA polymerase activity
Authors: Greenstein B. D. 
Published: December 2008

ABSTRACT
Cytosolic androgen receptors from neocortex, hypothalamus and anterior pituitary and ventral prostate glands were analysed by miniature isoelectric focusing and sucrose density-gradient centrifugation before and after precipitation of [3H]dihydrotestosterone (DHT)-bound complexes with ammonium sulphate. In the hypothalamus and neocortex (NH4)2SO4 precipitation appeared to cause heterodisperse peaks, and in the case of the ventral prostate there was a clear shift to a more basic isoelectric point. After sucrose density-gradient centrifugation all cytosols sedimented as large aggregates which appeared to dissociate into subunits in 0·4 m-KCl gradients. The functional significance of these altered forms was tested by nuclear uptake studies of cytosolic [3H]DHT-bound complexes, which could only be detected in brain and pituitary nuclei after prior precipitation with (NH4)2SO4, which also significantly increased extraction of ventral prostate [3H]DHT-bound complexes from the nucleus. The nuclei apparently responded to the (NH4)2SO4-precipitated and redissolved complexes by increased RNA polymerase activity. These results are consistent with the possibility that the neural androgen receptor is altered before interaction with the genome, and this alteration may be necessary for the action of the hormone to be expressed.
J. Endocr. (1984) 102, 181–188
Effects of prolactin on follicular oestradiol production in the rat
Authors: Uilenbroek J. Th. J. , van der Linden R. 
Published: December 2008

ABSTRACT
The effect of prolactin on follicular oestradiol production was studied in rat ovaries in which luteal tissue was absent. A silicone tube containing progesterone was implanted before first ovulation and removed 14 days later. This resulted in the presence of preovulatory follicles 2 days later and ovulation 60 h after removal of the implant. Prolactin concentrations were raised either by injection of purified prolactin or by implantation of pituitary tissue under the kidney capsule. Injections with 100 or 200 μg prolactin starting at the time of removal of the implant (16.00 h on day 0) had no effect on in-vitro oestradiol production by preovulatory follicles obtained on day 2 (day of pro-oestrus). However, implantation of two pituitary glands under the kidney capsule, 2 weeks before progesterone removal, resulted in significantly lower follicular oestradiol production, although ovulation was not inhibited. Lowering of serum prolactin by injections of bromocriptine resulted in an increased follicular oestradiol production.
These results indicate that, in addition to its well-known luteotrophic effect, prolactin can have a direct inhibitory effect on follicular oestradiol production. This effect might contribute to the reduced fertility seen during hyperprolactinaemia.
J. Endocr. (1984) 102, 245–250
Further study of oestrous cycles that follow interruption of spontaneous persistent oestrus in middle-aged rats
Authors: Everett J. W. 
Published: December 2008

ABSTRACT
Spontaneous persistent oestrus in certain middle-aged rats, when interrupted by an injection of LH, is usually followed by one or more short ovulatory cycles. A previous study disclosed that brief treatment with bromocriptine early in dioestrus blocks completion of the initial cycle whereupon persistent oestrus promptly returns, indirect evidence that the cycles are sustained through low-grade activation of the corpora lutea by prolactin. Further evidence of this is now presented by demonstration that administration of extrinsic prolactin at the time of the bromocriptine injection overcomes the blockage, apparently rescuing the corpora lutea and allowing completion of the cycle with renewed luteinization. Whereas bromocriptine treatment shortens the current dioestrus, the added prolactin restores the duration to at least that shown by 'LH-only' controls.
In a related experiment, when persistent oestrus was interrupted by an injection of phenobarbitone (without corpus luteum formation), most, of the rats remained dioestrous for only 2 days. In a few rats, this was followed by spontaneous completion of an ovulatory 4-day cycle. Hence, in the 'LH-only' group the small number of 4-day cycles may actually have gone to completion without dependence on the original set of corpora lutea.
In some of the 'LH-only' group, a possible relationship was examined between the prolactin level at the time of LH injection and the subsequent ability of the rat to sustain multiple cycles. Rats showing only one cycle averaged lower prolactin concentrations than those that presented multiple cycles or pseudopregnancy.
J. Endocr. (1984) 102, 271–276
Increase in ovulation rate after active immunization of sheep with inhibin partially purified from bovine follicular fluid
Authors: Henderson K. M. , Franchimont P. , Lecomte-Yerna M. J. , Hudson N. , Ball K. 
Published: December 2008

ABSTRACT
Four Romney ewes were actively immunized with a partially purified preparation of inhibin derived from bovine follicular fluid and their ovulation rates in four successive oestrous cycles were compared with those of four ewes receiving adjuvant alone. The ovulation rates of the ewes immunized with the inhibin preparation were significantly higher than those of the control ewes (2·06 ± 0·16 (s.e.m.) vs 1·31±0·06 ovulations/ewe, n= 4). Plasma concentrations of FSH and LH, measured in blood samples taken three times a week for 11 weeks, during which time each ewe was immunized three times, were not significantly different between the two treatment groups. These results suggest that active immunization with inhibinenriched follicular fluid may be a potential means of increasing fecundity in sheep.
J. Endocr. (1984) 102, 305–309
Effect of dehydration, haemorrhage and oviposition on serum concentrations of vasotocin, mesotocin and prolactin in the chicken
Authors: Nouwen E. J. , Decuypere E. , Kühn E. R. , Michels H. , Hall T. R. , Chadwick A. 
Published: December 2008

ABSTRACT
Serum concentrations of arginine vasotocin (AVT), mesotocin and prolactin were determined by radioimmunoassay in Rhode Island Red chickens during and after dehydration, haemorrhage and oviposition. During dehydration increased circulating levels of AVT, mesotocin and prolactin were found. As water deprivation proceeded, marked differences were observed. After an initial rise in serum AVT, mesotocin and prolactin levels during mild and moderate dehydration, concentrations of both AVT and prolactin tended to normalize during continued water deprivation, while those of mesotocin remained high throughout the whole dehydration experiment with the highest at the end of the water-deprivation period. Removal of 5 ml blood at intervals of 10 min during six consecutive time-periods did not affect serum osmolality and circulating levels of AVT and prolactin, but slightly increased mesotocin. These results suggest an osmoregulatory role for AVT and prolactin, whereas mesotocin may be involved in volume control. Finally, 1 min after oviposition, control values of 19·5 ±3·4 pmol AVT/1 (n=9) were raised more than sevenfold to 142·9±12·5 pmol/l (n=11). Thereafter, a decline occurred with a half-life for AVT of 13 min with raised serum levels up to 31 min after oviposition. In contrast, the serum concentrations of mesotocin and prolactin remained unaffected by oviposition.
J. Endocr. (1984) 102, 345–351
Role of prolactin in the photoperiodic control of moulting in the mink (Mustela vison)
Authors: Martinet L. , Allain D. , Weiner C. 
Published: December 2008

ABSTRACT
Beginning at the summer solstice adult female mink were maintained in long- or short-day photoperiods and treated with bromocriptine or prolactin. In control females kept under natural lighting conditions the moult coincided with the seasonal decrease in prolactin and resulted in the growth of a dense winter coat which was completed by the end of November. Long days, which slowed the decrease in plasma prolactin relative to animals in the natural photoperiod, induced a more or less complete moult followed by growth of a thin summer coat. On the contrary we observed an accelerated decrease in plasma prolactin concentrations followed by an early and brief moult in females kept under long days but treated with bromocriptine and in females under short days. The growth of a dense winter coat was completed by the end of September in all the females of the short-day group and in six of eleven females treated with bromocriptine. In the other five females, moult was followed by the growth of a summer coat. These results may suggest that the decline of prolactin after the summer solstice is responsible for the onset of the autumn moult, but the early, abbreviated moult and the growth of a winter coat observed in females kept under short days and treated with prolactin do not seem to support this hypothesis. However, the huge non-physiological levels of prolactin measured in the plasma of these females and the appearance of abnormal white under-hairs might suggest that the hormonal balance in this group was completely disturbed by the treatment. The physiological role of prolactin in the seasonal moulting cycle in mink is discussed.
J. Endocr. (1984) 103,9–15
Properties and ontogeny of the glucocorticoid receptor in the placenta and fetal lung of the sheep
Authors: Flint A. P. F. , Burton R. D. 
Published: December 2008

ABSTRACT
The cytosolic glucocorticoid receptor of ovine placental zona intima has been characterized and measured between day 51 of pregnancy and term, and levels compared with those in fetal lung. By ion-exchange and gel-filtration chromatography the molybdate-stabilized receptor was found to be an acidic molecule with Stokes radius approximately 8 nm; these physicochemical characteristics of the ovine placental receptor are comparable to those of receptors in glucocorticoid target tissues from non-ruminants. Concentrations of cytosolic receptor in placenta (mean, 139 fmol/mg protein) were lower than those in fetal lung (627 fmol/mg) at all stages of gestation investigated. To some extent this difference was accounted for by a twofold higher concentration of protein in placental cytosols compared with those from fetal lung. In both tissues, cytosolic receptor concentrations were maximal between days 91 and 130, when fetal adrenal steroid secretion is low; receptor concentrations decreased before term. Fetal hypophysectomy, which resulted in prolonged gestation, raised receptor concentrations in placenta, but not in fetal lung. In both tissues, apparent dissociation constants for [3H]dexamethasone binding to glucocorticoid receptors were in the range 0·5–7·1 nmol/l; these dissociation constants did not change consistently between day 100 and term. In whole-cell preparations of placenta and fetal lung incubated in vitro there was time-dependent specific binding of [3H]dexamethasone by nuclei, and binding of labelled cytosolic receptor to isolated nuclei occurred at all stages of gestation investigated. Binding of [3H]dexamethasone by cytosolic receptor from placenta and fetal lung was inhibited by progesterone and 17α-hydroxyprogesterone, as well as by cortisol, cortisone, 11-deoxycorticosterone and 11β-hydroxyprogesterone; 20α-hydroxyprogesterone and 17α,20α-dihydroxypregn-4-en-3-one were less effective. In experiments to evaluate the possible antagonistic action of progesterone in whole-cell preparations, uptake of [3H]dexamethasone by nuclei was increased up to twofold in placental minces incubated with aminoglutethimide or epostane, when progesterone synthesis was reduced by 98 and 92 per cent respectively. Nuclear uptake in minces of fetal lung was blocked by concentrations of progesterone found in placenta. The existence of a placental glucocorticoid receptor confirms that fetal cortisol may act directly on the placenta to induce the enzymatic changes controlling the onset of labour. Its availability early in pregnancy is consistent with the ability of administered glucocorticoid to induce labour at any time after day 90 of gestation. Progesterone in the placenta may act as a glucocorticoid antagonist, protecting the fetus against inappropriate induction of preterm labour resulting from high levels of glucocorticoids in the maternal circulation.
J. Endocr. (1984) 103, 31–42
Secretion of corticotrophin releasing factor-like activity by a human bronchial carcinoid cell line
Authors: Kirkland S. C. , Ellison M. L. 
Published: December 2008

ABSTRACT
The production of corticotrophin releasing factor (CRF) activity by human tumour cells in monolayer culture was investigated. The secretion of CRF activity by a bronchial carcinoid cell line was demonstrated using a rat pituitary cell monolayer system. The long-term production (5 years) of CRF activity suggested the synthesis and secretion of active factors by the tumour cells.
The CRF activity was concentrated from medium previously exposed to the tumour cells using batchwise extraction on columns packed with ODS. When these extracts were fractionated by analytical high pressure liquid chromatography, the CRF activity was resolved into two molecular forms.
J. Endocr. (1984) 103, 85–90
Heterogeneity of activity of the prolactin-releasing factor in the bovine hypothalamo–neurohypophysial complex
Authors: Yasuda N. , Yasuda Y. , Greer S. E. 
Published: December 2008

ABSTRACT
Fresh samples of bovine hypothalamic median eminence or hypophysial stalk extracted with 0·1 m-HCl and fractionated on Sephadex G-100 had two prolactin-releasing factor (PRF) components, the major one in the void volume (PRF-A) and the minor one in an elution position (partition coefficient (Kav) = 0·333) immediately after PRF-A (PRF-B). Similar fractionation of bovine posterior pituitary extracts showed two PRF peaks: PRF-A and another in a more retarded position than PRF-B (Kav = 0·645; PRF-C). Storage of bovine stalk extract at −20 °C for 1 year caused a shift from higher molecular weight PRF into PRF-C. Thyrotrophin-releasing hormone stimulated prolactin secretion, but its dose–response slope and chromatographic mobility were quite different from those for bovine tissue extracts. Secretion of prolactin induced by extracts of bovine hypophysial stalk is calcium dependent and is inhibited by dopamine.
J. Endocr. (1984) 103, 243–249
Thyroid hormone binding in rat liver cytosol
Authors: Morgan G. 
Published: December 2008

ABSTRACT
Binding of 3,5,3′-tri-iodothyronine (T3) and thyroxine (T4) to components of perfused rat liver supernatant fraction and isolated liver cell cytosol was studied. Of the four binding fractions in supernatant (X, A, Y and Z) separable by gel chromatography, both T3 and T4 bound preferentially to the A-fraction, which was shown to contain albumin as the major binding protein. When cytosol prepared from isolated cells was examined, T4 was again bound mainly in the A-fraction; however, T3 was observed to bind predominantly in the Y-region. Hormone binding to soluble protein in the latter system is thought to reflect the pattern in vivo, better than does binding in supernatant, although the possibility exists that the concentration of albumin observed in cytosol may be artifically high due to transfer of membrane-bound albumin during cell disruption. Nevertheless, albumin (possibly derived from more than one intracellular source) is capable of binding T4 in vivo. The presence of this protein within the hepatocyte may thus contribute to the high T4 binding capacity of the liver compared to other tissues.
J. Endocr. (1984) 103, 265–271
Androgen-binding proteins in sheep epididymis: characterization of a cytoplasmic androgen receptor in the ram epididymis
Authors: Carreau S. , Drosdowsky M. A. , Courot M. 
Published: December 2008

ABSTRACT
An androgen receptor (Rc) was demonstrated in caput, corpus and cauda epididymal cytosols of the ram. This receptor had a high affinity for 5α-dihydrotestosterone (Kd = 5·2 × 10−9 mol/l) and could be distinguished from the androgen-binding protein (ABP) by several characteristics. On polyacrylamidegel electrophoresis, Rc had a mobility of 0·37 and ABP 0·61; Rc sedimented in the 9S region of a linear sucrose gradient whereas ABP migrated in the 4·3S region; the molecular weights were 192 000 and 90 000 for Rc and ABP; their isoelectric points were 5·7 and 4·8–5·0; they were proteinaceous components since they were destroyed by proteolytic enzymes and heating (50 °C for Rc and 60 °C for ABP); they exhibited different half-times of dissociation: 20 h at 0 °C for Rc and 6 min for ABP, which is in agreement with their respective physiological roles, intra- and extracellular transport of androgens. The content of Rc-binding sites in caput epididymis was 18, in corpus 4 and in cauda 22 fmol/mg protein.
J. Endocr. (1984) 103, 273–279
Somatostatin inhibits prolactin release from the lactotroph primed with oestrogen and cyproterone acetate in man
Authors: Gooren L. J. G. , Harmsen-Louman W. , van Kessel H. 
Published: December 2008

ABSTRACT
The present study investigated the effect of administration of somatostatin (SRIF) on the release of prolactin in men. No effect was observed when SRIF was administered to eugonadal men. Release of prolactin was inhibited, however, when SRIF was administered to oestrogen-treated agonadal subjects (male-to-female trans-sexuals) and to an even greater degree when subjects had been pretreated with a combination of oestrogen and cyproterone acetate. This is consistent with findings in the rat. Thus in man, as in the rat, SRIF can inhibit prolactin secretion, but only after treatment with oestrogen.
J. Endocr. (1984) 103, 333–335