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SUMMARY
The secretion of growth hormone from anterior pituitary transplants under the kidney capsule of gonadectomized and hypophysectomized male rats was investigated with special regard to the importance of the mass of functioning pituitary tissue. Body growth and mammary gland development after testosterone stimulation were studied.
In rats with the pituitary gland autotransplanted to the kidney capsule body growth was markedly reduced. After administration of testosterone a few groups of alveoli only were seen in the mammary glands.
Hypophysectomized rats with four pituitary transplants (an autotransplant and three homotransplants) under the kidney capsule showed slightly better body growth than rats with an autotransplanted hypophysis. When compared with rats with intact pituitary glands body growth was markedly reduced. Mammary gland development after testosterone stimulation was as poor in rats with four pituitary transplants as in rats with an autotransplanted hypophysis.
These results suggest strongly that the normal secretion of growth hormone is regulated by the hypothalamus and that the deficiency of growth hormone in rats with the pituitary gland transplanted remote from the brain is due mainly to a loss of 'specific' stimuli from the hypothalamus and not to a 'non-specific' reduction in the amount of functioning pituitary tissue.
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Thyrotrophin (TSH) synthesis and secretion is under the positive control of thyrotrophin releasing hormone and under the negative control of the thyroid hormones. However, it is hypothesised that TSH has a direct effect on the regulation of its own synthesis through an intrapituitary loop mediated by pituitary TSH receptors (TSH-R). The aim of this investigation was to study the expression of TSH-R in normal human pituitary at mRNA and protein levels, and to compare the pattern of protein expression between different pituitary adenomas. Using RT-PCR we were able to detect TSH-R mRNA in the normal pituitary, and immunohistochemical studies showed TSH-R protein expression in distinct areas of the anterior pituitary. Double immunostaining with antibodies against each of the intrapituitary hormones and S100 revealed that TSH-R protein is present in thyrotrophs and folliculostellate cells. Examination of 58 pituitary adenomas, including two clinically active and two clinically inactive thyrotroph adenomas, revealed TSH-R immunopositivity in only the two clinically inactive thyrotroph adenomas. This study shows, for the first time, the presence of TSH-R protein in the normal anterior pituitary and in a subset of thyrotroph adenomas. The expression of TSH-R in the thyrotroph and folliculostellate cell subpopulations provides preliminary evidence of a role for TSH in autocrine and paracrine regulatory pathways within the anterior pituitary gland.
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hypothalamo-pituitary–adrenal (HPA) axis, a fundamental mechanism of adaptation and survival strategies. Exogenous (e.g., morphine) as well as endogenous opioids (β-endorphine and enkephalins) are believed to play an important although complex role in the
Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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Laboratory of Animal Nutrition,
Laboratory of Animal Breeding, Department of Animal Science, Agricultural University of Athens, 75, Iera odos, 11855 Athens, Greece
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restriction, which has no effect on birth weight, can alter the function of the hypothalamic–pituitary–adrenal (HPA) axis ( Hawkins et al. 1999 , 2000 ), which has been suggested to play a role in programming of the later disease ( Seckl 1997 ). Studies
Royal (Dick) School of Veterinary Studies, MRC Human Reproductive Sciences Unit, MRC/UCT, The Roslin Institute, University of Edinburgh, Roslin, Midlothian, Edinburgh EH25 9PS, UK
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Royal (Dick) School of Veterinary Studies, MRC Human Reproductive Sciences Unit, MRC/UCT, The Roslin Institute, University of Edinburgh, Roslin, Midlothian, Edinburgh EH25 9PS, UK
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evidence for a third GnRH ligand in the chicken to date. Both cGnRH-I and GnRH-II stimulate LH release from chicken pituitary in vitro ( Hattori et al . 1986 , Millar et al . 1986 ) and in vivo ( Chou et al . 1985 , Hattori et al . 1986 , Sharp
Department of Physiology, Department of Physiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 409-3898, Japan
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of adenovirus vector infection is poorly understood in endocrine cells. Castro et al . (1997) reported that infection of the primary cultures of anterior pituitary cells with an adenovirus expressing β-galactosidase (βgal), at multiplicities of
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A method for the enrichment of live thyrotrophic pituitary cells is described. Pituitary glands of young male rats were removed into Earle's solution and dispersed in a 0·1% trypsin solution containing 0·5% bovine serum albumin, pH 7·2.
Nylon fibres (25 μm) were used for the separation of the thyrotrophic cells, by stringing them across a plastic frame which fitted a plastic Petri dish containing the cell suspension. The fibres were washed with light petroleum (b.p. 60–80 °C) and carbon tetrachloride, hydrolysed with 3 m-HCl for 30 min at room temperature and washed with distilled water and phosphate-buffered saline (pH 7·2). The fibres were treated with thyrotrophin releasing hormone (TRH) alone or in the presence of soluble carbodiimide solution. After incubation for 1 h at room temperature, the fibres were transferred to a new Earle's medium and cells were released from the fibres by plucking them with a needle. The separated thyrotrophic cells were identified by radioimmunoassay and by electron microscopy.
Using the above-mentioned methods, enrichment of thyrotrophic cells was obtained. Thus, the amounts of TSH, prolactin, LH and GH released, during 2 h of incubation, by 1·5 × 106 unseparated cells were 6·8 ± 0·65, 4·1 ± 0·47, 4·8 ± 0·52 and 5·2 ± 0·68 μg respectively, while the same number of purified thyrotrophic cells released 76·1 ± 0·42, 1·2 ± 0·3, 0·6 ± 0·35 and 1·6 ± 0·22 μg of the same hormones (means ± s.e.m.).
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SUMMARY
The pars intermedia of the rat pituitary contains a peptide resembling the 18–39 portion of adrenocorticotrophic hormone (ACTH), which has been termed 'corticotrophin-like intermediate lobe peptide' (CLIP). It can be detected by its cross-reaction with an antiserum directed against the CO2H-terminal portion of the ACTH molecule; it has an amino acid composition identical to the 18–39 portion of human ACTH, except for one less glycine and an extra valine residue, and it is rapidly released from neurointermediate lobes maintained in organ culture. The pars intermedia also contains a peptide with an amino acid composition and biological potency identical to that of melanocyte-stimulating hormone (α-MSH) isolated from other mammals, and which accounts for the bulk of melanocyte-stimulating activity in the pituitary. Rat ACTH resembles human ACTH in amino acid composition, except for an extra valine and one less glycine residue. On the basis of these data it is proposed that ACTH is the precursor of α-MSH and CLIP, which are both present in the cells of the pars intermedia.
Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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Department of Pathology and
Department of Medicine,
Research Resource Center, University of Louisville, Louisville, Kentucky 40202, USA,
James Graham Cancer Center, University of Louisville, 580 South Preston St Baxter II, 324, Louisville, Kentucky 40202, USA
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and cloned and characterized pituitary tumor transforming gene ( PTTG ) from human testis ( Kakar & Jennes 1999 ). Our initial studies were based on the work of Pei & Melmed (1997) , who cloned PTTG from rat pituitary tumor cell line GH4. Cloning of
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Under the assumption that the impaired inhibitory effect of glucocorticoids on cell division is an important determinant in the progression of corticotrophic adenomas, it is postulated that the magnitude of proliferation and the resistance to glucocorticoids are correlated. To test this hypothesis, 67 dogs with pituitary-dependent hyperadrenocorticism were studied to determine whether a correlation could be demonstrated between the effect of dexamethasone administration on the activity of the pituitary–adrenocortical axis and the size of the pituitary gland as estimated by computed tomography.
The volumes of the pituitary glands as calculated from summations of subsequent images of pituitary areas, ranged from 11·8 to 3238·6 mm3. Among the three dimensions, the height of the pituitary was the most sensitive indicator of enlargement. Calculation of the pituitary height/brain area ratio (P/B ratio) allowed correction for the size of the dog. The P/B ratio had the highest discriminatory power in distinguishing enlarged (n=41) from non-enlarged (n=26) pituitaries.
The effects of dexamethasone (0·1 mg/kg) on the plasma concentrations of cortisol and ACTH and on the urinary corticoid/creatinine (C/C) ratios were expressed as percentage changes from the initial values. For ACTH, cortisol and C/C ratios these figures for resistance to dexamethasone were significantly correlated with the dimensions of the pituitary, particularly the height, volume and P/B ratio.
It is concluded that the magnitude of the expansion of pituitary corticotrophic adenomas is dependent upon the loss of restraint by glucocorticoids, i.e. the degree of insensitivity to glucocorticoid feedback.
Journal of Endocrinology (1997) 152, 387–394