bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute desensitization of pituitary FSH response to LHRH in ovariectomized rats: further evidence that in the presence of ovarian proteins the LHRH-dependent, LH-like component of FSH release becomes apparent
Authors: Lambalk C. B. , van Rees G. P. , Schoemaker J. , de Koning J. , van Dieten J. A. M. J. 
Published: December 2008

ABSTRACT
Pulsatile release of LHRH and short-term pituitary desensitization to LHRH in the rat are believed to be necessary for the maintenance of LH pulsatility. In contrast, FSH release is partly induced by LHRH release and is partly LHRH-independent. This LHRH-independent release of FSH is subject to inhibitory feedback control by ovarian proteins (probably inhibin), and may obscure an LHRH-induced shortterm loss of pituitary FSH responsiveness to LHRH. The object of this study was to establish whether short-term pituitary desensitization to single doses of LHRH results not only in a loss of LH response, but also of FSH response. Ovariectomized rats were used to eliminate the influence of steroid feedback.
A group of ovariectomized rats was pretreated with steroid-free bovine follicular fluid (bFF) to suppress LHRH-independent FSH release, and phenobarbital to suppress LHRH-dependent FSH release respectively, 7 and 1 h before administration of LHRH. Another group received phenobarbital only. The animals were injected sequentially with either low or high doses of LHRH (1·25 or 10 ng/100 g body weight at times 0 and at 80, 120 or 180 min, and 6·25 or 50 ng/100 g at 60 min). Blood was taken for FSH measurements before and 5 and 10 min after each injection. Rats pretreated with bFF and phenobarbital showed an acute FSH response related to the dose of injected LHRH. No dose–response curve was seen in animals which had only been pretreated with phenobarbital. A significantly attenuated FSH response to LHRH injections of 1·25 or 10 ng/100 g, given 20 min after an injection of 6·25 or 50 ng LHRH/100 g body weight respectively, was observed in animals pretreated with a combination of phenobarbital and bFF, but not in those treated with phenobarbital alone.
The present results confirm that FSH release is under dual control by LHRH and ovarian secretory proteins. When both LHRH-dependent FSH release and the LHRH-independent FSH release are suppressed, short-term desensitization of FSH release to exogenous LHRH can be demonstrated. It is concluded that the phenomenon of short-term pituitary desensitization to LHRH and inhibitory ovarian proteins may both play a role in the regulation of FSH release.
Journal of Endocrinology (1989) 123, 221–226
Maturational changes in the LH response of domestic fowl to synthetic chicken LHRH-I and -II
Authors: Wilson S. C. , Cunningham F. J. , Chairil R. A. , Gladwell R. T. 
Published: December 2008

ABSTRACT
Treatment of chickens at different stages of sexual development with a single i.v. injection of synthetic chicken LHRH (cLHRH)-I or -II stimulated a rise in the plasma concentration of LH within 1 min. The activity of cLHRH-II was 1·3- to 2·7-fold greater than that of cLHRH-I in sexually immature cockerels and hens as determined by the changes in the plasma concentration of LH during the 5 or 10 min after injection. This could be attributed to both a greater effectiveness of cLHRH-II to stimulate LH release and to a more prolonged action. Thus, LH concentrations in plasma were maximal within 1–2 min of injection of all doses of cLHRH-I but within 2–5 min of injection at the higher doses of cLHRH-II. The responsiveness of the pituitary gland to cLHRH-I and -II was substantially greater in the sexually immature cockerel than in the hen and diminished during sexual development of the hen. Coincident with the onset of egg laying, the characteristics of the LH response to cLHRH-II changed to consist of an initial rise during the first 2 min, followed by a more sustained increase with LH concentrations still rising 10 min after injection. In contrast, after injection with cLHRH-I, plasma concentrations of LH rose to a peak at 2 min and thereafter declined gradually. Treatment of the sexually immature hen with oestradiol, progesterone or a combination of both steroids did not enable the expression of a laying hen-type response to the injection of cLHRH-II. It would appear, therefore, that unidentified events associated with the final stages of sexual maturation bring about changes in the mechanism of action of cLHRH-II which differ from those of cLHRH-I.
Journal of Endocrinology (1989) 123, 311–318
Characterization of epidermal growth factor-related proteins from human urinary chorionic gonadotrophin
Authors: Hofmann J. , Hölzel F. , Hackenberg R. , Schulz K.-D. 
Published: December 2008

ABSTRACT
A urinary chorionic gonadotrophin (hCG) preparation, mitogenic for ovarian carcinoma cells, was analysed by gel filtration through Sephadex G-100 Superfine. The resulting fractions were tested for hCG and for properties of the epidermal growth factor (EGF) by radioimmunoassays (RIA) in comparison with their ability to stimulate the growth of EFO27nu ovarian carcinoma cells. The elution profile of the RIA activities for hCG corresponded to molecular weights of 12 and 71 kDa, whereas the mitogenic activity was found in peak fractions eluting at 7, 11 and 52 kDa, indicating the presence of mitogenic substances distinct from hCG or its β-subunit. In comparison experiments, radiolabelled recombinant human EGF eluted at 7 kDa from the column. The profile of EGF immunoreactivity determined in the eluant fractions of hCG preparation A correlated with the mitogenic potential. Eluant fractions with growth-promoting activity competed with 125I-labelled EGF in binding to EFO-27nu cells; the inhibition of EGF binding was correlated with the mitogenic potential and the EGF immunoreactivity. We assume that the 7 kDa component of the gel filtration eluate corresponds to monomeric EGF; the high molecular weight mitogens may represent EGF precursor protein fragments of various molecular size classes.
Journal of Endocrinology (1989) 123, 333–340
Ontogeny of pulsatile gonadotrophin secretion and pituitary responsiveness in male puberty in man: a mixed longitudinal and cross-sectional study
Authors: Wu F. C. W. , Borrow S. M. , Nicol K. , Elton R. , Hunter W. M. 
Published: December 2008

ABSTRACT
The onset of puberty is characterized by a sleep-associated increase in pulsatile LH secretion which is not observed in adults. The ontogeny of gonadotrophin secretion during pubertal maturation may reflect changes in endogenous LHRH secretion, pituitary sensitivity to LHRH and/or alterations in gonadal steroid feedback. To understand the interplay between these mechanisms, we have examined the pulsatile pattern of plasma LH, FSH, testosterone, oestradiol and prolactin between 20.00 and 09.00 h and the pituitary response to repeated exogenous LHRH stimulation in 16 boys with delayed puberty (age 16·3±2·7 (s.e.m.) years) on one to four occasions in a mixed longitudinal/cross-sectional analysis. Physical maturity was determined by Tanner G staging (1–5) and clinical progress followed for a mean duration of 22·4 ± 8·5 months during which 33 hormone profiles were obtained.
Nocturnal (23.00–09.00 h) LH pulse frequency increased to a peak of 0·54±0·03/h at stage 2 which was followed by a gradual decline to 0·42 ± 0·04/h at stage 5. The appearance of LH pulses in the evening (20.00–23.00 h), probably representative of the rest of the day, was delayed until mid-puberty from which point frequency increased to a peak of 0·53 ±0·08/h at stage 5. LH pulse amplitude showed a linear increase from stages 1 to 5, with nocturnal pulse amplitudes being higher than evening pulses throughout. FSH did not show a clear pulsatile pattern. The LH: FSH ratio reversed from < 1 to > 1 at stage 2. The LH response to exogenous LHRH increased in parallel with LH pulse amplitude. There was no difference in the pattern of LH response to repeated LHRH stimulation as puberty advanced; the first stimulus always elicited a greater response than subsequent doses. In contrast, the FSH response to LHRH was maximal at stage 1 and became attenuated thereafter. The estimated mean nocturnal LHRH concentration or amplitude did not show any increase during pubertal maturation from 20·42±11·57 at stage 1 to 35·96 ± 20·83 ng/l at stage 5.
In conclusion, the sequential changes in this study suggest that the sleep-entrained increase in LHRH pulse frequency plays a key role at the onset of puberty. By enhancing pituitary responsiveness and setting in motion a cascade of events, this peripubertal augmentation of LHRH pulse frequency can account for most of the subsequent changes in LH, FSH and testosterone secretion during pubertal development in the male without any apparent alteration in LHRH pulse amplitude.
Journal of Endocrinology (1989) 123, 347–359
Diabetes mellitus and the sodium electrochemical gradient across the brush border membrane of rat intestinal enterocytes
Authors: Debnam E. S. , Ebrahim H. Y. 
Published: December 2008

ABSTRACT
The effects of chronic diabetes mellitus of 4–5 weeks duration on the potential difference across the brush border membrane of rat small intestine (Vm) and on Na+-dependent uptake of d-glucose by jejunal brush border vesicles have been studied. Diabetes increased Vm in the jejunum from a mean value of −47.2 mV in control tissue to −57.4 mV in diabetic tissue (P<0.001) but was without effect on ileal Vm. Measurements of Vm during ion-substitution experiments revealed that the conductance of Na+ of the jejunal brush border was reduced by diabetes, whilst K+ and Cl− permeabilities were unaltered. Uptake studies using brush border vesicles and an Na+-electrochemical gradient showed that diabetes caused a 56% increase in the initial rate of uptake of d-glucose but was without effect on the peak to equilibrium ratio. Taken together, data from these two studies suggest that the lower Na+ permeability of the brush border in diabetes enhances the electrical and chemical driving force for active Na+-dependent uptake of glucose by reducing glucose-independent movement of Na+ across this membrane. Finally, the possible humoral factors involvedin this response to diabetes are discussed.
Journal of Endocrinology (1989) 123, 453–459
Follicle-stimulating hormones in anterior pituitary glands from children and adults differ in relation to sex and age
Authors: Wide L. 
Published: December 2008

ABSTRACT
Follicle-stimulating hormone (FSH) in extracts of the anterior lobe of pituitaries, collected at autopsy from 13 boys, 21 girls, 17 men and 26 women, was measured in terms of biological activity (B) in vitro by the Sertoli cell aromatase bioassay, and in terms of immunological activity (I) by a radioimmunoassay.
The highest concentration of FSH in the anterior lobe found by bioassay was in young girls, who had a mean value three to seven times higher than that in young and elderly men and women and nine times higher than that in young boys. The total amount of FSH in the pituitary found by bioassay and immunoassay was very much less in young boys than in all other groups.
The B/I ratio of FSH was higher for all the 27 children below 10 years of age than for any of the 43 adults. This difference in B/I ratio of FSH in whole pituitary extracts persisted in fractions after electrophoretic separation. The mean B/I ratio for young girls was 1·26 times higher than that for young boys and 2·25 times higher than that for adults. Young and elderly men and women had almost identical B/I ratios.
All extracts were analysed after electrophoresis and the median charge and charge homogeneity of FSH were estimated. The number of different forms of FSH in pituitary extracts from a child was at least 20–30, similar to that in an adult. In girls, the median charge of FSH was similar to that of young women and significantly less negative than in elderly women. The median charge of FSH in boys was more negative than in girls, but less negative than in both young and elderly men.
After treatment of pituitary extracts with neuraminidase, the median charge of FSH in infants was significantly more negative than that in adults. This, together with the differences in B/I ratios between children and adults, indicates a change at puberty in the molecular structure of FSH from juvenile to adult forms of the hormone.
Journal of Endocrinology (1989) 123, 519–529
CONJUGATES OF OVARIAN STEROIDS, INCLUDING 17α, 20β-DIHYDROXY-4-PREGNEN-3-ONE (MATURATION-INDUCING STEROID), ACCUMULATE IN THE URINE OF A MARINE TELEOST (PLAICE; PLEURONECTES PLATESSA)
Authors: Canario Adelino V. M. , Scott A. P. 
Published: December 2008

ABSTRACT
Free and conjugated 17α, 20β-dihydroxy-4-pregnen-3-one (17, 20β-P), 17α, 21-dihydroxy-4-pregnene-3, 20-dione (11-deoxycortisol) and 3α, 17α, 21-trihydroxy-5β-pregnan-20-one (3α, 17, 21-P-5β) were measured by radioimmunoassay in matching blood plasma and urine samples from plaice (Pleuronectes platessa) females at several ovarian maturity stages: post-vitellogenesis (IV), final oocyte maturation (V), and ovulation (VI).
Free steroids were generally low in all samples. Conjugated steroids were up to 2 orders of magnitude higher in urine than in plasma samples. Conjugated 17, 20β-P was higher in stage V than in stage IV or VI females. Conjugated 11-deoxycortisol was higher in stage IV and V females. Conjugated 3α, 17, 21-P-5β was higher in stage V and VI females.
These results support earlier studies which indicated that 17, 20β-P was the most likely maturation-inducing steroid (MIS) in plaice, and that the urine might be a vehicle for steroid pheromones synthesized by the gonads.
INSULIN AND VARIATION IN GLUCOSE LEVELS MODIFY THE SECRETION RATES OF THE GROWTH HORMONE-INDEPENDENT INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN-1 IN THE HUMAN HEPATOBLASTOMA CELL LINE HEP G2
Authors: Cotterill A.M. , Cowell C.T. , Silink M. 
Published: December 2008

ABSTRACT
The plasma level of the GH-independent insulin-like growth factor binding-protein-1 (IGFBP-1) is regulated inversely by insulin. In this study the effect of insulin and changes in the glucose concentration on in-vitro IGFBP-1 secretion by the Hep G2 cell line was studied. Media from confluent cells in 12 replicates were collected for consecutive periods: initial control (20 h), study(6 h) and recovery (20 h). Insulin suppressed IGFBP-1 secretion maximally at 100 mU/1 (−32%) within 6 h. The secretion of IGFBP-1 was stimulated by a decrease in the glucose concentration in the medium, maximally (+25%) with a decrease from 24 to 6 mmol/l. Stimulation by varying glucose levels and suppression by insulin of IGFBP-1 secretion persisted on return to control conditions after the removal of physiological concentrations of glucose (4 - 12 mmol/l) and insulin (50 - 500 mU/1). The findings in the Hep G2 cell line that a variation in the physiological concentrations of glucose and insulin each independently regulate IGFBP-1 secretion suggest that this cell line may by a suitable model for further in-vitro studies of the regulation of secretion of IGFBP-1.
Iodide autoregulation of functional and morphological differentiation events in the FRTL-5 rat thyroid cell strain
Authors: Beere H. M. , Tomlinson S. , Bidey S. P. 
Published: December 2008

ABSTRACT
The role of cyclic AMP (cAMP) attenuation in mediating the autoregulatory actions of iodide on thyroid cell iodide uptake and surface morphological responses to TSH was investigated in the rat thyroid cell strain FRTL-5. Preincubation of cells for 6 h with up to 1 mmol sodium iodide/1 led to a progressive reduction in both accumulation of cAMP and iodide uptake responses to TSH. Forskolin-mediated accumulation of cAMP and iodide uptake responses were similarly reduced after preincubation with iodide, whilst the iodide accumulation response to dibutyryl cAMP (dbcAMP) was unaffected. The inhibitory effects of iodide on TSH or forskolin-responsive iodide accumulation were not seen if preincubation was limited to 3 h, and were also abolished by the thionamide drug methimazole (1 mmol/l). Medium containing 1 μmol iodide/l prevented the appearance of the surface microvilli and pseudopodia normally observed after re-addition of TSH or forskolin, although cytoplasmic retraction was still apparent under such conditions. In contrast, iodide was without effect on the ability of dbcAMP (1 mmol/l) to induce cytoplasmic retraction and the formation of microvilli and pseudopodia. Inclusion of 1 mmol sodium perchlorate/l together with iodide during preincubation failed to prevent or reduce the suppression by iodide of either iodide uptake or surface morphological differentiation, suggesting that both aspects of autoregulation may involve surface actions of organified iodide. These observations indicate that in FRTL-5 cells, autoregulation by iodide of both the functional and surface morphological actions of TSH principally reflects the attenuating activities of organified iodide on intracellular cAMP generation.
Journal of Endocrinology (1990) 124, 19–25
Differential effects of a unilateral hypothalamic lesion on ovulation and compensatory ovarian hypertrophy in hemiovariectomized adult rats
Authors: Cruz M. E. , Moran J. L. , Jaramillo L. P. , Domínguez R. 
Published: December 2008

ABSTRACT
The effects were analysed of a unilateral lesion in the anterior or medial hypothalamus made on the day of oestrus on right or left hemicastrated rats. On the day of oestrus after two consecutive oestrous cycles of the same length, the ovulation rate in rats with lesions in the anterior left hypothalamus was lower than in control hemicastrated animals (5/16 vs 18/20; P<0·01), and normal in those rats with lesions in the right side (14/18). None of the animals with lesions in the left side of the anterior hypothalamus and with the left ovary in situ ovulated (0/7), but 5/9 with the right ovary in situ did ovulate (P<0·05). Lesions on either side of the medial hypothalamus did not modify ovulation rate. Compensatory ovulation was reduced in those animals with lesions in the right anterior hypothalamus and with the right ovary in situ. Lesions in either side of the medial hypothalamus reduced compensatory ovulation. Lesions in the right side of the anterior and medial hypothalamus increased compensatory ovarian hypertrophy in the left ovary and decreased it in the right ovary. Lesions in the left side of the anterior hypothalamus increased compensatory ovarian hypertrophy in the left ovary only, whereas lesions in the left side of the medial hypothalamus reduced compensatory ovarian hypertrophy in the right ovary. The results suggest that the information arising in each side of the anterior and medial hypothalamus plays different roles in the ipsi-and contralateral ovary, when either the left or the right ovary is absent.
Journal of Endocrinology (1990) 124, 37–41
Differential ovulatory responses of the right and left ovaries of the adult rat to unilateral lesion and anaesthesia of the cervico-vaginal plexus
Authors: Domínguez R. 
Published: December 2008

ABSTRACT
Differences were observed in the ovulation rates of the right and left ovaries in response to unilateral lesions of the cervico-vaginal plexus (CVP) followed by pseudopregnancy or by anaesthesia of the CVP induced with panthocaine plus adrenaline (right ovary 6·7±0·4 (s.e.m.) vs left ovary 4·6 ± 0·9; P<0·05). Pseudopregnancy (days showing a dioestrous smear after copulation with a vasectomized male before an oestrous smear following a pro-oestrous one) lasted longer in rats with a lesion in the CVP than in a control pseudopregnant group (14·9 ± 0·5 vs 11·2 ± 0·5; P < 0·01). Anaesthesia of the CVP performed on each day of the oestrous cycle did not modify the ovulation rate compared with laparotomized animals. Both laparotomy and anaesthesia of the CVP performed on oestrus or day 1 of dioestrus blocked ovulation but when they were performed on day 2 of dioestrus or pro-oestrus they failed to do so (laparotomy 9/18 vs 12/14, P<0·05; anaesthesia of CVP 3/11 vs 17/17, P < 0·05). The number of ova shed by the left ovary in animals with anaesthetized CVP was lower than by the right ovary (4·5 ± 0·6 vs 6·2 ± 0·5; P<0·05). These results add further support to the idea that the CVP participates in the regulation of ovulation rate, and that the left ovary is less adaptable than the right when innervation is challenged.
Journal of Endocrinology (1990) 124, 43–45
Endometrial response to deciduogenic stimulus in ovariectomized rhesus monkeys treated with oestrogen and progesterone: an ultrastructural study
Authors: Sengupta J. , Given R. L. , Talwar D. , Ghosh D. 
Published: December 2008

ABSTRACT
The present work continues our aim of establishing an experimental model to study the decidual cell reaction to an artificial deciduogenic stimulus in the long-term ovariectomized rhesus monkey treated with oestrogen followed by progesterone. The fine structural details of decidual, granular and plaque cells, which constituted the endometrial cellular response to the deciduogenic stimulation in the present study, revealed striking similarities with those reportedly present in an endometrial response to blastocyst implantation in the rhesus monkey. Plaque epithelia showed a significant degree of hypertrophy, hyperplasia and differentiation followed by a steady degeneration by day 32 (equivalent to day 16 after trauma) of treatment. The plaque cells were shown to contain numerous regular-shaped mitochondria, polyribosomes and large amounts of rough endoplasmic reticulum (RER) in their cytoplasm and were characteristically arranged in clusters or acini formation surrounded by discrete basal laminae. As early as day 28 of treatment, the initiation of stromal decidual cell transformation was noted and, by day 48, a sizeable pool of decidual cells was found. The decidual cells had rounded nuclei and elaborate arrangements of interconnected cisternae of RER which were often moderately dilated and filled with amorphous, electron-dense material. Granular cells were characterized by eccentrically located nuclei and numerous membrane-bound, electron-dense granules in their cytoplasm and were found in increasing numbers in the stroma around decidual cells, blood vessels and glandular epithelia. Based on the ultrastructural and temporal characteristics of the endometrial cells studied it has been suggested that the cells have secretory functions, and that the differential maturation profiles of the cell types might be caused by their differences in sensitivities and by their integral response to progesterone.
Journal of Endocrinology (1990) 124, 53–57