bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for differences in low density lipoprotein processing by porcine granulosa and luteal cells in vitro: effect of addition of serum for plating of granulosa cells on lipoprotein metabolism
Authors: Rajkumar K. , Ly H. , Schott P. W. , Njaa B. , Murphy B. D. 
Published: December 2008

ABSTRACT
The present studies were carried out to compare the low density lipoprotein (LDL) metabolism by freshly isolated immature porcine granulosa cells with that by luteal cells. Furthermore, we have examined the effect of serum used for plating of granulosa cells on lipoprotein degradation and utilization. In incubation studies, addition of LDL as an exogenous substrate had a mild stimulatory effect on progesterone accumulation by granulosa cells, while it exhibited a dose-dependent stimulatory effect on luteal cells. When granulosa and luteal cells were incubated with 125I-labelled LDL, membrane binding of LDL occurred in both cell types, but only luteal cells were capable of internalizing the bound LDL. Granulosa cells in incubation degraded LDL much less in comparison with luteal cells, and the amount varied with the maturity of the cells. When granulosa cells were plated with graded amounts of serum which was withdrawn for 48 h following plating, they exhibited enhanced LDL degradation in a serum concentration-dependent fashion. Addition of serum for plating selectively enhanced utilization of LDL, but not high density lipoprotein (HDL) for progesterone accumulation by the cells in culture. Time-course studies on LDL degradation by granulosa cells following serum withdrawal indicate that the ability of cells to degrade LDL decreased in a time-dependent fashion. Serum withdrawal selectively decreased utilization of LDL but not HDL for progesterone secretion. It is concluded that immature granulosa cells have a limited capability to utilize cholesterol carried by LDL. However, when cultured in the presence of serum, cells acquire the ability to utilize more efficiently LDL-carried cholesterol for progesterone secretion which is then lost following long-term withdrawal of serum from culture.
Journal of Endocrinology (1989) 122, 557–564
Post-somatostatin rebound secretion of growth hormone is dependent on growth hormone-releasing factor in unrestrained female rats
Authors: Sugihara H. , Minami S. , Wakabayashi I. 
Published: December 2008

ABSTRACT
To examine the characteristics of GH secretion following the termination of the infusion of somatostatin, unrestrained adult female Wistar rats were subjected to repeated infusions of somatostatin separated by 30-min control periods. When somatostatin was infused for 150 min at a dose of 3, 30 or 300 μg/kg body wt per h, the magnitude of the rebound GH secretion increased in a dose-dependent manner. The infusion of somatostatin at a dose of 300 μg/kg body wt per h for 60, 150 or 240 min progressively augmented the size of the rebound GH secretion. When an antiserum to rat GH-releasing factor (GRF) was injected i.v. 10 min before the end of the infusion, the peak amplitude of the rebound GH secretion (300 μg/kg body wt, 150 min) was reduced to less than 20% of that of control rats. The rebound GH secretion (300 μg/kg body wt per h, 150 min) was augmented by a bolus injection of human GRF (1 μg/kg body wt). The combined effect of the end of infusion of somatostatin and a bolus injection of GRF on the amount of GH secreted was additive. The plasma GH response to GRF was completely inhibited when human GRF (3 μg/kg body wt per h) and somatostatin (300 μg/kg body wt per h) were infused simultaneously for 150 min. The magnitude of the rebound GH secretion following the termination of the co-administration was larger than that following the somatostatin infusion alone, but this rebound was not enhanced by a bolus injection of human GRF. Moreover, the amount of GH secreted was significantly less than that after the termination of somatostatin infusion plus a bolus injection of human GRF in the absence of preceding GRF administration.
These results suggest that at least part of the influence of somatostatin on GH secretion is exerted at the level of the hypothalamus through modulating the release of GRF. In addition, it is inferred that the simultaneous infusion of GRF and somatostatin induces the attenuation of the GH response to GRF through a receptor effect.
Journal of Endocrinology (1989) 122, 583–591
Effect of ovarian hormones, pregnancy and lactation on somatostatin and substance P in the alimentary tract of mice
Authors: Bailey C. J. , Conlon J. M. , Flatt P. R. 
Published: December 2008

ABSTRACT
Immunoreactive somatostatin and substance P were determined in extracts of alimentary tract (stomach to colon) from the following groups of adult female mice: intact control, ovariectomized, ovariectomized and treated with oestradiol (50 μg/kg per day) and/or progesterone (2 mg/kg per day) for 30 days, 19-day-pregnant, and 10-day-postpartum lactating. Ovariectomy increased the somatostatin concentration of the stomach (by 52%, P < 0·05), jejunum (by 116%, P < 0·01) and caecum (by 114%, P < 0·01). These effects were partially or totally prevented by the oestradiol and progesterone treatments, especially the oestradiol-progesterone combination, except for an increase (by 126%, P < 0·01) in gastric somatostatin after treatment with oestradiol alone. Lactation also increased gastric somatostatin (by 108%, P < 0·001), but the somatostatin concentration of other regions of the alimentary tract (jejunum to colon) was reduced (by 21–55%, P < 0·05) in pregnant and lactating mice. The concentration of substance P was increased by ovariectomy in stomach (by 69%, P < 0·01), duodenum (by 84%, P < 0·05), ileum (by 163%, P < 0·001) and caecum (by 57%, P < 0·01). This effect was partially or totally prevented by treatment with progesterone alone and by the oestradiol-progesterone combination, but not by oestradiol alone. Pregnancy and lactation increased gastric substance P by 46% (P < 0·01) and 61% (P < 0·001) respectively, but substance P concentrations in other regions of the alimentary tract were not significantly altered. The results suggest that ovarian oestrogens and progestogens are important in the maintenance of normal concentrations of somatostatin and substance P in the gastrointestinal tract of female mice.
Journal of Endocrinology (1989) 122, 645–650
Responses of hypothalamic and pituitary mRNA to physical and psychological stress in the rat
Authors: Harbuz M. S. , Lightman S. L. 
Published: December 2008

ABSTRACT
In-situ hybridization histochemistry was used to measure corticotrophin-releasing factor mRNA and proenkephalin A mRNA in the paraventricular nucleus (PVN), and pro-opiomelanocortin (POMC) mRNA in the anterior pituitary of the rat. Levels of message were determined at 1, 2, 4 and 8 h after exposure to a variety of physical and psychological stresses. Corticotrophin-releasing factor mRNA in the PVN and POMC mRNA in the anterior pituitary increased in response to i.p. hypertonic saline, restraint and swim stress but not to cold stress. Proenkephalin A mRNA was raised only in response to the physical stress of i.p. injection of hypertonic saline. These results suggest that different afferent pathways and hypothalamic neurotransmitters may be involved in mediating the hypothalamic response to different physical and psychological stresses.
Journal of Endocrinology (1989) 122, 705–711
Characterization of endometrial and myometrial oxytocin receptors in the non-pregnant ewe
Authors: Ayad V. J. , Wathes D. C. 
Published: December 2008

ABSTRACT
Oxytocin-binding sites in the endometrium and myometrium of the non-pregnant ewe were characterized. [3H]Oxytocin bound to a single site in both tissues with high affinity; dissociation constants were determined to be 1·96 nmol/l in endometrium and 2·12 nmol/l in myometrium. Oxytocin binding was enhanced by divalent cations with a similar order of potency in both tissues: Co2+> Mn2+> Ni2+> Mg2+ > Zn2+> Ca2+. The endometrial and myometrial binding sites showed the same specificity for oxytocin analogues and related peptides, having high affinity for oxytocin, [Arg8]-vasopressin, [Lys8]-vasopressin, and the oxytocin-specific agonists [Gly7]-oxytocin and [Thr4,Gly7]-oxytocin. The results suggest that oxytocin receptors present in the endometrium and myometrium of the ewe are similar both to each other and to classical oxytocin receptors.
Journal of Endocrinology (1989) 123, 11–18
Relationship between growth hormone-releasing hormone and somatostatin in the rat: effects of age and sex on content and in-vitro release from hypothalamic explants
Authors: Ge F. , Tsagarakis S. , Rees L. H. , Besser G. M. , Grossman A. 
Published: December 2008

ABSTRACT
Secretion of GH in the rat has been shown to be dependent upon age and sex. Using rat hypothalamic explants in vitro, we have studied the release and hypothalamic content of GH-releasing hormone (GHRH) and somatostatin in male and female Wistar rats at four different ages (10, 30 and 75 days, and 14 months). Basal release of GHRH was not significantly different between male and female rats, but at all ages males released more GHRH in response to stimulation by both 28 and 56 mmol potassium/l than female rats (P<0·05). Neither basal nor potassium-stimulated release of GHRH altered with age. In contrast, both basal and potassium-stimulated secretion of somatostatin increased significantly (P<0·01) with age, but was the same in the two sexes. Hypothalamic GHRH content, as assessed by the extractable tissue content following incubation, was significantly (P<0·01) lower in 10-day-old rats compared with older rats, but remained constant after 30 days of age. Somatostatin content, in contrast, increased progressively with age (P<0·01). The hypothalamic content of the two peptides was the same in both sexes.
In conclusion, our findings demonstrate that male rats release more GHRH in vitro than female rats, possibly reflecting the increased pulse amplitude of GH seen in males in vivo; the progressive fall in secretion of GH previously reported during ageing appears to parallel the progressive increase in somatostatin release and content seen in our in-vitro system.
Journal of Endocrinology (1989) 123, 53–58
Control of inhibin production by primate granulosa cells
Authors: Hillier S. G. , Wickings E. J. , Saunders P. T. K. , Dixson A. F. , Shimasaki S. , Swanston I. A. , Reichert L. E. , McNeilly A. S. 
Published: December 2008

ABSTRACT
In-vitro data from experiments on rats implicate granulosa cells as primary sites of hormone-dependent ovarian inhibin biosynthesis, but no equivalent data exist for primates. We have used the common marmoset (Callithrix jacchus) to investigate inhibin biosynthesis in primate granulosa cells in vitro and to determine its relationship to preovulatory follicular development. To relate the production of immunoactive inhibin to follicular maturity, we studied primary granulosa cell cultures from follicles at progressive stages of preovulatory development. Granulosa cells from 'large' (≥2·0 mm diameter) follicles expressed high rates of inhibin production and steroidogenesis (progesterone), and were positively regulated by human (h)LH in vitro. Less mature granulosa cells from 'medium' (1·1–1·9 mm) and 'small' (≤ 1·0 mm) follicles expressed proportionately lower rates of inhibin production and steroidogenesis, but each parameter was stimulated in a dose- and time-dependent manner by hFSH in vitro. The stimulatory action of hFSH on immunoactive inhibin was augmented by the presence of testosterone or oestradiol; testosterone (but not oestradiol) also augmented the steroidogenic response to hFSH. Marmoset luteal tissue also produced inhibin in vitro and expressed an ∼1·5 kb inhibin α-subunit mRNA, confirming the corpus luteum as a source of ovarian inhibin in primates.
These results provide direct experimental evidence that primate granulosa cells produce inhibin. They suggest that production of inhibin by immature granulosa cells is initially induced by FSH and subject to modulation by follicular steroids. During advanced preovulatory development, granulosa cell inhibin production becomes directly responsive to LH, thereby indicating a role for LH in the control of peri- and postovulatory inhibin secretion by the primate ovary.
Journal of Endocrinology (1989) 123, 65–73
Changes in cytosolic 3,5,3′-tri-iodo-l-thyronine (T3) binding activity during administration of l-thyroxine to thyroidectomized rats: cytosolic T3-binding protein and its activator act as intracellular regulators for nuclear T3 binding
Authors: Nishii Y. , Hashizume K. , Ichikawa K. , Miyamoto T. , Suzuki S. , Takeda T. , Yamauchi K. , Kobayashi M. , Yamada T. 
Published: December 2008

ABSTRACT
Changes in the amount of cytosolic 3,5,3′-tri-iodo-l-thyronine (T3)-binding protein (CTBP) and its activator during administration of l-thyroxine (T4) to thyroidectomized rats were investigated. Thyroidectomy decreased the amount of CTBP in the kidney, whereas the activator was not significantly modified by thyroidectomy. The activator was increased by administration of T4 to thyroidectomized rats. The amount of CTBP was also increased by administration of T4. The activator increased the maximal binding capacity (MBC) without changes in the affinity constant for T3 binding in CTBP. A T4-induced increase in MBC in cytosol inhibited nuclear T3 binding in vitro by competition of T3 binding between CTBP and the nuclear receptor.
These results suggest that thyroid hormone increases the capacity for cytosolic T3 binding through increasing the amount of CTBP and its activator, and that these increases play a role in regulating the amount of T3 that binds to its nuclear receptor.
Journal of Endocrinology (1989) 123, 99–104
Thyroid hormone affects the development of Sertoli cell function in the rat
Authors: Palmero S. , de Marchis M. , Gallo G. , Fugassa E. 
Published: December 2008

ABSTRACT
The relationship between thyroid activity and Sertoli cell function has been investigated in prepubertal rats. Male 28-day-old Wistar rats were used to prepare Sertoli cells by sequential enzyme digestion of the testes. Hypothyroidism, induced by oral administration of methimazole from the day of birth, was characterized by a severe retardation of body and testis growth and a net inhibition of the increase in Sertoli cell γ-glutamyl transpeptidase (GGT) activity as well as in androgen-binding protein (ABP) and lactate production, which normally occur during postnatal development of Sertoli cells. The functional parameters of Sertoli cells from hypothyroid 28-day-old rats approximated to those of cells from euthyroid 15-day-old animals. These results are consistent with the impairment of protein synthesis in Sertoli cells from hypothyroid rats compared with controls.
Body and testis growth were improved and Sertoli cell functions were restored with 3,3′,5-tri-iodothyronine (T3) replacement therapy. An excess of T3 in the serum, induced by daily i.p. injections of T3 (100 μg/kg body wt) during the last week before the rats were killed, failed to induce changes in body and testis growth or in the activity of GGT and lactate dehydrogenase of Sertoli cells. Cells from hyperthyroid rats exhibited a specific decrease in ABP production. These results indicate that thyroid hormone is necessary for the postnatal maturation of Sertoli cell function and suggest a regulatory role of the hormone on gametogenic development in the prepubertal rat.
Journal of Endocrinology (1989) 123, 105–111
Changes in serum concentrations of ACTH, corticosterone and in growth following morning or evening injection of female rats with porcine growth hormone
Authors: Sillence M. N. , Etherton T. D. 
Published: December 2008

ABSTRACT
The present study was designed to examine the effects of stress, associated with daily handling and placebo injection, on growth and adrenal activity in female rats. A second objective was to examine the effects of porcine GH (pGH) on growth and on serum concentrations of ACTH and corticosterone.
Treatments were administered in the morning (08.00 h) in semi-darkness, or in the evening (20.00 h) towards the end of the light period and were timed to coincide with reported periods of high and low adrenal sensitivity to ACTH.
Handling of and s.c. injection of saline into female rats (initial body weight 220 g) each morning for 21 days did not affect growth, food intake or organ weights. In contrast, daily handling and saline injection each evening caused a marked reduction in weight gain (25%), food intake (12%) and liver weight (8%), accompanied by a trend towards an increase in adrenal weight (11%), but no change in serum corticosterone concentrations.
In a second experiment, treatment of female rats (initial body weight 180 g) with pGH (5·6 mg/kg) daily at 08.00 h caused a significant improvement in weight gain (17%), but food intake and organ weights were unaltered. Daily injection of rats with pGH at 20.00 h caused a greater relative improvement in weight gain (45%) than did treatment at 08.00 h as the growth impairment caused by the stress of handling was counteracted. The adverse effect of evening injections of saline on food intake was also counteracted by pGH. Changes in liver and adrenal weights, however, were not attenuated by pGH treatment. Serum corticosterone concentrations were barely altered by pGH treatment, but serum ACTH concentrations were increased markedly (65–136%) by pGH in response to both morning and evening injection.
The results show that mild stress associated with daily handling and injection can have a profound effect on the growth of rats, but lend no support to the hypothesis that the growth impairment is mediated by corticosterone. Female rats handled and treated in the morning provide a good physiological growth model of a non-stressed animal, but rats treated in the evening are more responsive to the anabolic effects of pGH. It is suggested that pGH causes a reduction in adrenal sensitivity to ACTH and, in the absence of increased corticosterone output, high serum ACTH concentrations may contribute to part of the anabolic activity of pGH.
Journal of Endocrinology (1989) 123, 113–119
Production of calcitonin gene-related peptide from human cancer cells
Authors: Zaidi M. , Breimer L. H. , MacIntyre I. 
Published: December 2008

ABSTRACT
Calcitonin (CT) is produced ectopically from a variety of non-thyroidal cancers. The CT genes also encode another peptide, calcitonin gene-related peptide (CGRP) which is a potent vasodilator. In the present study we have used immunochemical and chromatographic methods to demonstrate the presence and characterize the molecular forms of CGRP in cultured human cancer cells. Using two highly sensitive and specific radioimmunoassays, we have detected immunoreactive CGRP (i-CGRP) in cell extracts and cell-exposed media of cultured promyelocytic leukaemia (HL60) and bronchogenic carcinoma (BEN) cells. The mean i-CGRP content of the HL60 and BEN cell extracts was 2 and 45 pmol/g wet weight respectively. On gel filtration and high performance liquid chromatography, the immunoreactive material was found to be heterogeneous, though a major proportion co-eluted with synthetic human CGRP(1–37), suggesting structural identity with the intact CGRP molecule. Finally, we have discussed some interesting features of CT-gene peptide expression in tumour cells.
Journal of Endocrinology (1989) 123, 159–165
Episodic ovarian inhibin secretion is not due to LH pulses in anoestrous ewes
Authors: Campbell B. K. , McNeilly A. S. , Baird D. T. 
Published: December 2008

ABSTRACT
In sheep, secretion of oestradiol by the ovary is stimulated by pulses of LH but the factors controlling ovarian inhibin secretion are not well understood. We have investigated the effect of a single injection of LH on the ovarian secretion of inhibin. Six anoestrous Finn–Merino ewes which had one ovary autotransplanted to a site in the neck had jugular and timed ovarian venous blood samples collected at 10-min intervals for a total of 5 h.
The secretion rates of both inhibin (1–3 ng/min) and oestradiol (0·5–8 ng/min) were similar to those observed during the breeding season indicating significant follicular development in these animals.
After injection of 2·5 μg NIH-LH-S25 intravenously the concentration of LH in plasma rose from a baseline of 1·8 ±0·1 (s.e.m.) μg/l to a peak of 3·9 ±0·3 μg/l (P<0·01). This LH pulse stimulated a corresponding increase (P<0·01) in oestradiol secretion from a basal level of 0·9±0·2 ng/min to a peak of 4·6±0·6 ng/min that occurred within 30 min of injection. Although inhibin secretion was episodic in nature, increases were not related to either exogenous or endogenous LH pulses.
We conclude that, in contrast to oestradiol, the secretion of inhibin by the ovary is not controlled acutely by changes in plasma levels of LH during anoestrus.
Journal of Endocrinology (1989) 123, 173–179
Leydig cell recovery following a second challenge with ethane-1,2-dimethanesulphonate is enhanced by short intervals between cytotoxin administration to rats
Authors: Edwards G. , Lendon R. , Morris I. D. 
Published: December 2008

ABSTRACT
Ethane-1,2-dimethanesulphonate (EDS) destroys Leydig cells in the testis of the adult rat and subsequently a new population of Leydig cells develops. It has been reported that EDS is not cytocidal to the new immature Leydig cell population. In the present study, the effect of increasing the time-interval between injections of EDS on cytotoxicity to Leydig cells was examined. At time-intervals of 4–10 weeks between injections the response was similar to that seen after a single injection of EDS to the adult rat. Four days after the second injection, EDS was found to reduce substantially serum testosterone concentrations and in-vitro binding of 125I-labelled human chorionic gonadotrophin (hCG) to testicular LH receptors which can be correlated with Leydig cell destruction. However, when the interval was only 2 or 3 weeks there was no reduction in serum testosterone, and 125I-labelled hCG binding was not so markedly reduced. During days 1–6 after a second injection of EDS, administered 3 weeks after the first, there were marked reductions in serum testosterone concentrations and in 125I-labelled hCG binding to testis homogenates within 24 h. Recovery from the effects of EDS was rapid, and increased Leydig cell activity was seen from 2 to 6 days after injection. In contrast to the established changes in the adult rat, there was only a 50% reduction in the number of Leydig cells positive for 3β-hydroxysteroid dehydrogenase 2 days after the second injection of EDS, and after 6 days the number of cells had increased. These experiments show that the immature Leydig cell of the rat is sensitive to the cytotoxic effects of EDS but that the temporal changes in Leydig cell activity after EDS treatment are different in developing and mature Leydig cell populations. The data are consistent with the view that EDS is preferentially cytotoxic towards steroidogenically active Leydig cells, allowing the resident population of precursor cells to continue to respond to the prevailing homeostatic mechanisms.
Journal of Endocrinology (1989) 123, 197–203
Muscarinic effects on the hydroxy- and methoxyindole pathway in the rat pineal gland
Authors: Finocchiaro L. M. E. , Scheucher A. , Finkielman S. , Nahmod V. E. , Pirola C. J. 
Published: December 2008

ABSTRACT
[3H]Quinuclidinyl benzylate ([3H]QNB)-binding sites, showing similar properties to cholinergic muscarinic receptors in other tissues, were disclosed in the rat pineal gland. Functionality of these receptors was demonstrated, as in-vitro muscarinic activation by pilocarpine increased the pineal metabolic production of the hydroxyindole derivatives 5-hydroxytryptophan and serotonin, with a slight effect on melatonin biosynthesis. Electric-field stimulation of pineal slices caused similar metabolic effects. These effects were inhibited by muscarinic blockade with atropine and enhanced by neostigmine inactivation of acetylcholinesterase. These results suggest that acetyl-choline is the neurotransmitter involved. Cholinergic activity may, therefore, regulate indole metabolism in the pineal gland.
Journal of Endocrinology (1989) 123, 205–211