| 1. |
- Brönnegård, M., et al.
(author)
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Glucocorticoid receptor messenger ribonucleic acid in different regions of human adipose tissue
- 1990
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In: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 127:4, s. 1689-1696
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Journal article (peer-reviewed)abstract
- The expression of glucocorticoid receptor (GR) messenger RNA (mRNA) was investigated in sc adipose tissue and isolated adipocytes from the abdominal and gluteal regions in men and women using a human GR complementary RNA probe. GR mRNA levels were 2-fold higher in female than in male abdominal tissue or adipocytes, whereas in gluteal tissue or adipocytes no sex differences were observed. GR mRNA levels in female abdominal adipocytes were 50% higher than in corresponding female gluteal adipocytes; the opposite was observed corresponding in males. Northern blot analysis of total cellular RNA isolated from abdominal and gluteal adipocytes showed hybridization of the human GR probe to an RNA species of approximately 7.1 kilobases in both regions. No sex or regional differences in GR mRNA stability were observed. The human metallothionein II (hMTII) mRNA, which is regulated by glucocorticoids at the transcriptional level, showed an opposite sex and regional pattern as GR mRNA. However, in gluteal adipose tissue no sex differences were observed in hMTII mRNA levels. The expression of beta-actin mRNA, which is not regulated by glucocorticoids, showed no sex or regional variation. By immunocytochemistry, using an anti-GR-monoclonal antibody, cytoplasmic as well as nuclear staining for GR was demonstrated in both sexes and both regions. In conclusion, variations in GR mRNA levels between sexes and body regions may explain the well known sex and tissue differences in effects of glucocorticoids on human adipose tissue.
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| 2. |
- LaPolt, P S, et al.
(author)
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Basic fibroblast growth factor induction of granulosa cell tissue-type plasminogen activator expression and oocyte maturation : potential role as a paracrine ovarian hormone.
- 1990
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In: Endocrinology. - 0013-7227 .- 1945-7170. ; 127:5, s. 2357-63
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Journal article (peer-reviewed)abstract
- Gonadotropin-induced ovulation is associated with oocyte maturation and preovulatory increases of tissue plasminogen activator (tPA) expression. Basic fibroblast growth factor (bFGF), an angiogenic factor found in many organs including the ovary, modulates steroidogenesis in granulosa cells and increases PA activity in endothelial cells. Here studies were performed to examine the possible roles of bFGF as an intragonadal regulator of tPA expression and oocyte maturation. In cultured granulosa cells, bFGF caused a time-dependent (onset at 24 h) and dose-dependent (ED50 = 0.6 nM) increase (up to 5-fold) in tPA enzyme activity as measured by the fibrin overlay technique. Northern blot hybridization also revealed that treatment of cells with bFGF (2 nM) increased the level of the 22S tPA messenger RNA. Slot blot analysis indicated that the effects of bFGF were time dependent and dose dependent; tPA message levels increase before tPA activity levels. bFGF (0.6 nM) also significantly increased granulosa cell cAMP production in both the absence and presence of a phosphodiesterase inhibitor. In follicle-enclosed oocytes incubated for 24 h in media with or without increasing concentrations of LH or bFGF, germinal vesicle breakdown was observed in only 1.6% of controls, but 85% of LH (1 microgram/ml)-treated oocytes underwent maturation. Likewise, bFGF induced germinal vesicle breakdown (10-80%) over a dose range of 0.6 to 333 nM. In the same follicles, bFGF, like LH, also stimulated prostaglandin E production. These results, coupled with the identification of bFGF in growing follicles, suggest that bFGF acts as an intraovarian inducer of granulosa cell tPA gene expression and oocyte maturation.
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| 3. |
- Oikawa, M, et al.
(author)
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Expression of gonadotropin-releasing hormone and prothymosin-alpha messenger ribonucleic acid in the ovary.
- 1990
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In: Endocrinology. - 0013-7227 .- 1945-7170. ; 127:5, s. 2350-6
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Journal article (peer-reviewed)abstract
- GnRH exerts paradoxical effects on ovarian cells through specific receptors. Based on observed direct effects of GnRH and its antagonists on ovarian functions, the presence of endogenous ovarian GnRH-like peptide(s) has been postulated. In an attempt to detect the ovarian expression of GnRH or related genes at the RNA level, we used the reverse transcription-polymerase chain reaction (RT-PCR) to amplify GnRH mRNA levels. Total RNA from rat ovaries was converted to first strand cDNA using reverse transcriptase and amplified in PCR using a pair of primers complementary to the rat GnRH cDNA. The DNA products obtained were subcloned into plasmid vectors, and their sequences were determined. The most prominent PCR product of 462 basepairs (bp) was unexpectedly identified as a fragment of prothymosin-alpha cDNA previously found in the spleen. This cDNA was obtained because of an identical 10 bp match with the 3' end of one of the GnRH primers. Northern blot analyses using the cloned prothymosin-alpha cDNA as probe revealed the presence of mRNA for this factor in ovary, thymus, testis, placenta, and hypothalamus. RT-PCR amplification of hypothalamus and granulosa cell messages indicated the presence of a 244-bp product with a sequence identical to that of GnRH. To further confirm the presence of GnRH messages in the ovary, a second set of GnRH primers was used. PCR amplification of cDNA from hypothalamus, granulosa cells, and whole ovary yielded a 241-bp product identical to the authentic GnRH sequence based on analysis on both strands. In contrast, no PCR product was evident after amplification of thyroid cDNA. Our data demonstrated the expression of mRNA for GnRH and prothymosin-alpha in the ovary. Although the exact ovarian role of the immune hormone awaits further study, the detection of GnRH transcript in the ovary suggests potential intragonadal roles of this decapeptide.
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| 4. |
- Peng, X R, et al.
(author)
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Localization of luteinizing hormone receptor messenger ribonucleic acid expression in ovarian cell types during follicle development and ovulation.
- 1991
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In: Endocrinology. - 0013-7227 .- 1945-7170. ; 129:6, s. 3200-7
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Journal article (peer-reviewed)abstract
- The action of LH is mediated through specific plasma membrane receptors that are both up- and down-regulated in the ovary during the reproductive cycle. Using immature rats treated with PMSG and hCG as a model system, we have studied the regulation and distribution of LH receptor mRNA in different cell types during follicle development, ovulation, and luteinization by Northern blot and in situ hybridization. In untreated rats, LH receptor mRNA was below the detection level in granulosa cells, cumulus cells, and oocytes, while low levels of LH receptor mRNA were found in the thecal cells. After stimulation with PMSG, expression of LH receptor mRNA was enhanced in the thecal-interstitial cells, while a more dramatic increase in receptor mRNA abundance took place in granulosa cells of large tertiary follicles. In these follicles, the abundance of LH receptor mRNA varied among different subpopulations of granulosa cells, with mural granulosa cells close to the basement membrane exhibiting higher levels than granulosa cells located closer to the antrum, and cumulus cells and the oocyte lacking detectable hybridization signal. The uneven expression of LH receptor mRNA endows different ovarian cells with varying hormonal responsiveness. After an ovulatory dose of hCG, LH receptor mRNA levels were dramatically decreased, particularly in the granulosa cells of preovulatory follicles, to reach the lowest levels just before ovulation. During the transformation of ovulated follicles into corpora lutea, the expression of LH receptor message was again increased. Our results reveal that the previously documented regulation of the LH receptor-binding activity during ovarian development correlates with expression of the LH receptor transcripts, suggesting that the LH receptor gene is regulated in a complex manner during the periovulatory period to achieve cell-specific expression together with gonadotropin induction and suppression of receptor gene activity.
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| 5. |
- Persson, Per, et al.
(author)
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Effects of gastrin on calcium homeostasis in chickens
- 1991
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In: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 129:3, s. 1162-1166
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Journal article (peer-reviewed)abstract
- As in the rat, gastrin and an extract of the acid-producing part of the stomach (proventriculus) were found to lower the blood Ca2+ concentration in the chicken. Furthermore, gastrin enhanced the uptake of 45Ca into the femur. It has been suggested previously that gastrin causes hypocalcemia in the rat by releasing gastrocalcin, a hypothetical hormone thought to reside in the acid-producing part of the stomach. The results of the present study in the chicken are in agreement with this concept. Not only exogenous, but also endogenous gastrin lowered blood calcium levels. Thus, the serum gastrin concentration was increased in response to ranitidine-evoked blockade of the gastric acid output; the rise in gastrin was associated with a transient drop in blood calcium. Also, food intake produced a rise in the serum gastrin concentration and a transient drop in blood calcium. However, injection of ranitidine or food intake in proventriclectomized (acid-producing part of the stomach extirpated) chickens failed to lower blood calcium, supporting the view that the gastrin-evoked hypocalcemia depends upon an agent in the gastric (proventriculus) mucosa. We suggest that endogenous and exogenous gastrin evoke hypocalcemia in the chicken by the same mechanism as that which has been postulated in the rat, i.e. by mobilization of the candidate hormone gastrocalcin from endocrine cells in the acid-producing gastric mucosa.
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| 6. |
- Carmignac, Daniekke F, 1951, et al.
(author)
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Growth hormone binding protein in the rat: effects of gonadal steroids
- 1993
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In: Endocrinology. - 0013-7227. ; 133:6, s. 2445-52
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Journal article (peer-reviewed)abstract
- In normal rats, females have higher circulating GH-binding protein (GHBP) levels than males, whereas in the GH-deficient dwarf (Dw) rat, there is no sexual dimorphism in plasma GHBP, suggesting that GH secretion may be involved in this difference. In order to study the relationship between gonadal steroids and GH on GHBP and GH receptor regulation, the levels of plasma GHBP, hepatic bovine GH, and human GH (hGH) binding as well as GHBP and GH receptor messenger RNA (mRNA) have now been studied in normal, Dw, hypophysectomized (Hx), or ovariectomized (Ovx) rats, subjected to different GH and gonadal steroid exposure. In normal male rats, estradiol (E2, 12.5-25 micrograms/day for 1 or 2 weeks) markedly increased plasma GHBP and hepatic hGH, and bGH binding. These effects of E2 were diminished in Dw rats, absent in Hx rats, but restored in Hx rats given exogenous hGH. Plasma GHBP rose in female rats given E2, and fell in females given the anti-estrogen tamoxifen. Ovx animals had lower plasma GHBP and hepatic GH binding which was reversed by E2, but not testosterone treatment. Continuous hGH infusions in Ovx rats restored hepatic GH binding, and increased plasma GHBP. In Dw males, hGH increased plasma GHBP and hepatic GH binding, whereas testosterone had no effect on GHBP or GH receptors and did not affect their up-regulation by hGH. Hepatic levels of GHBP-, and GH receptor mRNA transcripts showed the same trends in response to steroid or GH treatment, but the differences were rarely significant, except in Ovx animals which had higher GHBP mRNA transcripts after GH or E2 treatment. Thus E2 and GH increase both plasma GHBP and hepatic GH receptor binding. GH up-regulates GHBP in the absence of E2, whereas E2 treatment does not raise GHBP in the absence of GH. Whereas some of the effects of estrogen could be mediated via alterations in GH secretion, estrogen may also directly influence GHBP production at the liver, but only in the presence of GH
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| 7. |
- Fairhall, Keith M, 1951, et al.
(author)
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Effect of food withdrawal and insulin on growth hormone secretion in the guinea pig.
- 1990
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In: Endocrinology. - 0013-7227. ; 127:2, s. 716-23
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Journal article (peer-reviewed)abstract
- The guinea pig is unusual in that its postnatal growth appears to be independent of GH even though its pituitary gland produces a GH molecule. The effects of fasting on the GH secretory pattern and the GH responses to insulin, GH-releasing factor (GRF), and somatostatin (SS) during fasting have now been studied by automatic microsampling of blood in chronically cannulated normal guinea pigs. Withdrawal of food in both male and female guinea pigs changed the GH secretory pattern dramatically. The normal episodic GH secretory pattern [large GH peaks occurring at 3.6 +/- 0.4-h intervals over a low (approximately 0.5-1.5 ng/ml) baseline secretion] was altered to a pattern of more continuous GH output, characterized by a 10-fold elevated baseline secretion (5-15 ng/ml) with no large secretory episodes or troughs. Glucose injections (three injections of 600 mg, iv, at hourly intervals) in fasted guinea pigs lowered their elevated blood GH levels significantly (from 9.1 +/- 1.1 to 6.5 +/- 0.9 ng/ml). Insulin injections (1, 2, or 6 U, iv) inhibited spontaneous GH pulses in normally fed animals, but had little effect on the high continuous GH tone during fasting. The elevated GH secretion in fasted animals could be inhibited by continuous infusion of SS or a single iv injection of a long-acting SS analog. The secretion of GH during fasting could be further increased, either by injections of GRF (two injections of 2 micrograms, iv, 90 min apart), producing peak levels of 102 +/- 16 and 68 +/- 21 ng/ml (above a baseline output of 8.8 +/- 2.2 ng/ml), or by a continuous iv infusion of GRF (12 micrograms/h). Because the GH secretory pattern in the guinea pig is so sensitive to nutrition and insulin, this species may provide an interesting model in which to study selectively the metabolic, as opposed to growth-promoting, actions and regulation of GH.
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| 8. |
- Ohlsson, Claes, 1965, et al.
(author)
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Embryonic stem cells express growth hormone receptors: regulation by retinoic acid.
- 1993
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In: Endocrinology. - 0013-7227. ; 133:6, s. 2897-903
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Journal article (peer-reviewed)abstract
- Embryonic and fetal growth are generally considered to be independent of pituitary GH. However, it has been demonstrated recently that 18-day-old rat embryos and rat fetuses express GH receptors, suggesting that GH could play a role in early development. The aim of the present investigation was to determine whether preimplantation embryos also express GH receptors. Germ line competent mouse embryonic stem (ES) cells and cultured mouse preimplantation embryos were examined with Northern blot analysis, RNAse-protection solution-hybridization assays, reverse transcription/polymerase chain reaction assays and immunohistochemistry for the detection of GH receptors. Northern blot analysis of ES cells using a probe corresponding to the extracellular domain of the GH receptor demonstrated the presence of two transcripts (1.2 and 4.5 kilobases). The RNAse-protection solution-hybridization assay revealed that ES cells express approximately one sixth of the GH-receptor messenger RNA (mRNA) levels expressed in liver from pregnant mice. Treatment of cultured ES cells with retinoic acid (100 nM) for 6 days increased GH-receptor mRNA levels (P < 0.01). GH-receptor mRNA was further identified in ES cells, preimplantation embryos, muscle, liver, and placenta by a reverse transcription/polymerase chain reaction assay. In humans it has previously been shown that exon 3 of the GH-receptor is deleted in the placenta. However, none of the studied mouse tissues had a deletion of the GH-receptor mRNA corresponding to exon 3 of the human GH receptor. GH-receptor immunoreactivity was identified on the cultured ES-cells by immunohistochemistry. In conclusion, we have in the present study shown that germline competent ES cells and preimplantation mouse embryos express the GH receptor transcript and that this transcription is increased by retinoic acid in ES cells. Furthermore, the presence of GH-receptor immunoreactivity on the ES cells indicates that the GH-receptor transcript is translated.
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| 9. |
- Sandstedt, J, et al.
(author)
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Disproportional bone growth and reduced weight gain in gonadectomized male bovine growth hormone transgenic and normal mice.
- 1994
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In: Endocrinology. - 0013-7227. ; 135:6, s. 2574-80
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Journal article (peer-reviewed)abstract
- Sex steroids have been shown to influence longitudinal bone growth during sexual maturation, partially by increased GH secretion. Mice transgenic for metallothionein promoter bovine GH were developed by pronuclear injection as a model with sex steroid-independent GH secretion. Prepubertal normal and transgenic, male and female mice were either gonadectomized or sham operated. The growth was divided into two segments: peripubertal growth from 30-60 days of age and adult growth from 60-90 days of age. Orchidectomy resulted in a decreased growth rate of the lumbar spine and a decreased weight gain during the peripubertal growth, whereas tibia growth was unaffected. The alteration in proportions between the lumbar spine and the tibia was apparent for both normal and bovine GH transgenic mice, suggesting that the effect was not mediated via decreased GH secretion. Orchidectomy resulted in increased adult tibial growth, whereas weight gain and lumbar growth were unaffected. In female mice, gonadectomy did not influence these parameters during either time period studied. In summary, we present data indicating that the male gonads in a GH secretion-independent manner stimulate pubertal growth of the spine and inhibit the tibial growth of adult animals.
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| 10. |
- Xu, X, et al.
(author)
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Postreceptor events involved in the up-regulation of beta-adrenergic receptor mediated lipolysis by testosterone in rat white adipocytes.
- 1993
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In: Endocrinology. - 0013-7227. ; 132:4, s. 1651-7
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Journal article (peer-reviewed)abstract
- In the previous studies we have shown that testosterone increases lipolytic responsiveness to catecholamines in rat white adipocytes, and that is associated with an up-regulation of beta-adrenergic receptor density. However, the postreceptor events involved in the testosterone induced enhancement of beta-adrenergic receptor activated lipolysis in these cells have not been adequately studied, and were therefore investigated in the present study. Male Sprague Dawley rats were divided into three groups: control, castrated, and castrated treated with testosterone. The beta-adrenergic receptor-mediated cAMP accumulation, measured with RIA after isoproterenol (a beta-adrenergic agonist) stimulation was decreased in castrated rats, and reversed by testosterone treatment, suggesting a testosterone effect at or proximal to adenylate cyclase. However, no differences between the groups were found in abundance of G alpha protein messenger RNAs (G alpha s, G alpha i-1, and G alpha i-2) as analyzed by Northern blot and a solution hybridization RNase protection assay, or in G protein mass measured with a quantitative enzyme-linked immunosorbent assay in fat cell membrane preparation. Lipolysis stimulated by N6-monobutyryl-cAMP was reduced in castrated rats and recovered by testosterone treatment, suggesting that components distal to the adenylate cyclase, i.e. protein kinase A (PKA) and/or hormone sensitive lipase (HSL) also are involved in testosterone regulation of lipolysis. In conclusion, these and previous results suggest that the testosterone-induced increase in lipolytic response to catecholamines in rat white adipocytes is mediated through several events including an increased beta-adrenergic receptor density, probably an increased adenylate cyclase activity and an increased protein kinase A/hormone sensitive lipase activity at the postreceptor level with apparent absence of effect on the expression of G-proteins.
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