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Magnetic resonance imaging of the pituitary gland in a patient with secondary hemochromatosis is described. On T1-weighted images, the anterior lobe had almost no signal intensity, and only the high-signal posterior lobe was seen. These findings are compatible with the distribution of iron deposition and clinical symptoms in hemochromatosis.
BACKGROUND: Farquhar (1957) initially described the folliculo-stellate cells in the rat anterior pituitary gland and found them to be located in groups around follicles throughout the anterior lobe. Soji and his co-workers have published a series of reports concerning cell-to-cell communication in the male rat hypophysis involving folliculo-stellate cells as mediated through a gap junctional network and recorded a reduction in junctional number following castration that was reversed by the administration of testosterone (Soji and Herbert, 1990, Anat. Rec., 226:342-346; Soji et al., 1990, Anat. Rec., 226:337-341). METHODS: Animals were ovariectomized at 10 days of age and separated into three groups: (1) intact control, (2) ovariectomized controls, (3) ovariectomized and given either estradiol, testosterone, or progesterone. On days 10, 20, 30, 40, and 45, the pituitary gland from animals in each group was removed and processed for ultrastructural examination. RESULTS: Gap junctions in the intact control female rats initially appeared between adjacent folliculo-stellate cells on day 20. Their numbers linearly increased until the animals reached the age of 45 days. In contrast, there was a suppression in the number of gap junctions present in the ovariectomized groups and a marked enhancement of the junctions in each of the three steroid-treated groups. CONCLUSIONS: These findings support the observations made in the male rat in which it was found that the development of gap junctions in the anterior pituitary gland of the rat is dependent in part on the presence of sex steroid hormones.
T1-weighted magnetic resonance (MR) images of the pituitary gland and sella turcica routinely demonstrate a region of high signal intensity in the neurohypophysis. High-resolution MR imaging studies of the sella turcica in 200 subjects with a normal or abnormal sella were analyzed. The hyperintensity was found in the images of about 90% of healthy subjects and patients with microadenoma, in only 43% of patients with macroadenoma, and in 12% of patients with empty sellae. The signal was absent in several patients with functional or anatomic abnormalities of the hypothalamic-hypophyseal axis. It is concluded that the high signal intensity in the posterior lobe of the pituitary gland is present in most healthy individuals and that its absence in many patients with large intrasellar masses and empty sellae is due to compression of posterior lobe tissue. Its absence in diabetes insipidus further suggests a relationship between hyperintensity and the functional status of the hypothalamic-hypophyseal axis.
Cocaine- and amphetamine-regulated transcript (CART) mRNA and CART peptide are abundant in the hypothalamic nuclei that control anterior pituitary function. CART peptide has also been localized in the anterior pituitary gland itself, although its role in pituitary function has not as yet been elucidated. In the present study, we investigated the localization and function of CART peptide in the anterior pituitary gland. Immunohistochemical observations revealed that CART peptide colocalized with FSH and LH in gonadotroph cells but that it was absent from the other hormone-producing cells. Immunoelectronmicroscopy suggested that CART peptide and gonadotropin were colocalized in the same secretory granules. CART peptide suppressed prolactin release from dispersed anterior pituitary cells 15 min after its addition into the media [basal production, 234.9 +/- 14.6 ng/ml vs. CART 55-102 peptide 100 nm, 125.0 +/- 18.2 ng/ml (P < 0.01, n = 5)]. Prolactin release was suppressed by CART in a dose-related manner; on the other hand, CART peptide did not affect the secretion of other anterior pituitary hormones. CART peptide synthesis by these cells was elevated 15 min after the addition of leptin to the media (100 nm), as determined by immunoblotting, but LHRH (10 nm) did not significantly affect CART peptide expression. These findings suggest that CART synthesis in the anterior pituitary may be stimulated by leptin and that CART peptide may play a role in the regulation of anterior pituitary hormone secretion in the rat.
Total cytoplasmic RNA, isolated from bovine anterior pituitary glands, directed the synthesis of primarily two proteins in a wheat germ cell-free system. Analysis of wheat germ cell-free products by sodium dodecyl sulfate-slab gel electrophoresis, direct immunoprecipitation with prolactin aatibody, and prolactin- and growth hormone-specific radioimmunoassay indicated that the two proteins were pre-prolactin and pre-growth hormone. Agarose-urea-gel electrophoresis of poly(A)-containing RNA revealed the presence of a large symmetrical RNA peak with an estimated size of approximately 15 S. The RNA contained in this peak was eluted from the gel and translated in the wheat germ cell-free system. Analysis of the translation products by electrophoresis, direct immunoprecipitation, and radioimmunoassay resulted in the detection of only pre-prolactin. The extent of pre-prolactin mRNA purification was assessed by synthesizing DNA complementary to gel-purified pre-prolactin mRNA and then following the hybridization of this cDNA to gel purified pre-prolactin mRNA. The result of this hybridization is consistent with the cell-free translation studies, namely that pre-prolactin mRNA is the predominant mRNA component of pituitary poly(A)-containing RNA.
One-half of pituitary-intact or sham-operated rats survive infection with 10(9) colony-forming units of Salmonella typhimurium, whereas rats without a pituitary gland all die within a few days. When the dose of S. typhimurium is reduced 600-fold, 15-25% of the hypophysectomized rats survive, and the survival rate is significantly enhanced by administration of tetracycline, recombinant interferon gamma (IFN-gamma), or recombinant growth hormone (GH). The protective effect of GH is abolished by heat inactivation or with an antibody to GH. Spleens from normal and hypophysectomized rats treated with tetracycline, IFN-gamma, or GH have 59-99% fewer bacteria 5 days after infection as compared to control rats. Peritoneal macrophages from hypophysectomized rats that are infected in vitro with S. typhimurium kill half as many extracellular bacteria as compared to pituitary-intact rats, and this bactericidal capacity is significantly augmented 75-95% by either GH or IFN-gamma. These data establish that the pituitary gland is essential for homeostasis during an infectious episode and that GH plays an important role in host resistance by augmenting the ability of macrophages to kill S. typhimurium.
The pituitary gland in the little (lit) mutant mouse was analyzed with respect to the cytoarchitecture of the pars distalis and the volumetric density of immunoreactive growth hormone (GH) cell granules in neonatal lit/lit and normal C57BL mice. At 8 days postnatally the volume of GH granules/total tissue was significantly less in the lit/lit pars distalis, and the cells were loosely arranged, as compared with the normal pars distalis. In newborn mice a statistically significant difference could not be detected between normal and lit/lit mice with respect to the volumetric density of GH granules; however, differences occurred in the cytoarchitectural organization of the pars distalis. These differences included prominent vascular channels and well-defined cords and clusters of cells in the normal newborn mice, in contrast to indistinct vascular elements and a more diffuse arrangement of cells in lit/lit.
1. Homogenates of neural lobes of bovine pituitary glands were fractionated by differential ultracentrifugation. 2. Neurosecretory vesicles were isolated by sucrose-gradient ultracentrifugation and membranes were obtained after hypo-osmotic lysis of the particles. 3. A method is described for the isolation of a preparation of purified neuronal plasma membranes by using a fraction enriched in nerve endings as a starting material. 4. The purity of the subcellular fractions was estimated by enzyme assays and by examination with the electron microscope. 5. On the basis of the results it was estimated that neuronal plasma membranes constitute more than 30% of the protein of the nerve endings and neurosecretory vesicles more than 45% of the total amount of protein in the homogenate. 6. The proteins of membranes of neurosecretory vesicles and of plasma membranes were solubilized by means of sodium dodecyl sulphate. Polyacrylamide-gel electrophoresis of such preparations showed that both membranes contained a large number of proteins, including three glycoproteins.
A case is presented of delayed radiation necrosis of the pituitary gland region which appeared 2 years after tonsillar carcinoma surgery, followed by radiotherapy, in a 62-year old woman. Magnetic resonance imaging suggested the presence of an adenoma, metastases or craniopharyngioma, of the pituitary gland region. The lesion was resected, totally, using the fronto-orbital approach. Histopathological examination showed radionecrosis of the neurohypophysis. The patient was released from the hospital in a good health condition without neurologic deficits. On the basis of our case and reports of other authors, we can conclude that complications may arise as a result of radiation damage to neighbouring structures and there is also potential to induce malignant disease.
Relationships among the release of prolactin, the effect of oestrogens and the proliferation of prolactin-secreting cells were studied under several experimental conditions. Administration of sulpiride or oestradiol released prolactin and stimulated cell proliferation in the anterior pituitary gland of adult male rats. Clomiphene completely abolished the rise in cell proliferation, but did not interfere with the sulpiride-induced release of prolactin. Treatment with oestradiol plus sulpiride significantly increased serum prolactin concentrations and the mitotic index compared with the sum of the stimulation produced by both drugs separately. Bromocriptine abolished the stimulatory effect of oestradiol on the serum prolactin concentration and on cell proliferation. In oestradiol- and/or sulpiride-treated rats, 80% of the cells in mitoses were lactotrophs. The remaining 20% did not stain with antisera against any of the pituitary hormones. The number of prolactin-secreting cells in the anterior pituitary gland significantly increased after the administration of oestradiol or sulpiride. The results demonstrate that treatment with sulpiride and/or oestradiol increases the proliferation and the number of lactotrophs in the anterior pituitary gland of the rat.
1. Homogenates of neural lobes of bovine pituitary glands were fractionated by differential and density-gradient ultracentrifugation and the distribution of adenosine triphosphatase (ATPase) activity was studied. It was shown that all the activity was membrane-bound. 2. On the basis of ionic requirements the ATPase activity was grouped into three categories: (a) Mg(2+)-dependent, (b) Ca(2+)-dependent and (c) Mg(2+)+Na(+)+K(+)-dependent (ouabain-sensitive) ATPases. The activity in the absence of bivalent cations was negligible. The ratio between the activities of the three ATPases varied between the different subcellular fractions. 3. Preincubation of the subcellular fractions with deoxycholate increased the activity of the Mg(2+)+Na(+)+K(+)-dependent enzyme, whereas the Mg(2+)- and Ca(2+)-activated ATPases were either unaffected or slightly inhibited. Triton X-100 solubilized the Mg(2+)- and Ca(2+)-ATPases; however, the activity of the Mg(2+)+Na(+)+K(+)-ATPase was abolished by the concentration of Triton X-100 used. 4. All the subfractions displayed unspecific nucleotide triphosphatase activity towards GTP, ITP and UTP. These substrates inhibited the hydrolysis of ATP by all three ATPases. ADP also inhibited the ATPases. 5. Polyacrylamide-gel electrophoresis of extracts containing the Mg(2+)- and Ca(2+)-dependent ATPase activity solubilized by Triton X-100 revealed the presence of two enzymes; one activated by either Mg(2+) or Ca(2+) and the other activated only by Ca(2+). 6. In sucrose density gradients the distribution of vasopressin was different from that of all three types of ATPases. It is therefore suggested that the neurosecretory granules do not possess ATPase activity.
The changes in levels of prolactin (PRL) and growth hormone (GH) in plasma and the pituitary gland and their transcripts were measured in turkey hens at different physiological stages by radioimmunoassay and dot blot hybridization analysis, respectively. The levels of tPRL mRNA in the pituitary gland increased from those of the immature group to the egg-laying group, reaching a maximum during the incubation and a minimum during the moulting stages. Changes in pituitary levels of PRL and PRL mRNA followed a similar trend and consequently were highly correlated (r2 = 0.83), whereas a significant but lower correlation was observed between circulating and pituitary levels (r2 = 0.62). Less significant changes were measured for tGH mRNA, with maximum and minimum levels measured in the pituitaries of egg-laying and non-laying hens, respectively. These data suggest that although changes in concentration of PRL are correlated with the reproductive stage of the turkey hen, coordinate changes in levels of GH are not.
Follicles displaying a positive periodic acid-Schiff reaction to a colloid substance in the anterior pituitary gland have been observed in many vertebrates, including humans. It is also known that these follicles greatly increase in number and size with age. We therefore performed histochemical analysis of these colloid follicles in the senescent porcine pituitary gland in order to clarify their nature and biological significance. Results from various histological stains suggest that the colloid contains some polysaccharides or glycoproteins. In addition to the histological stains, lectin histochemistry revealed that the colloid contains sialic acid, N-acetyl galactosamine and galactose. Also, lectin staining indicated that some glycoproteins, most likely Asn-linked sialoglycoproteins, are localized in the colloid. The cells (FS cells) surrounding the colloid were densely stained with an antibody to S-100 protein but were not stained with antibodies to any other anterior pituitary hormones. Frequently mammotrophs (PRL cells), and occasionally gonadotrophs (LH cells) were found closely associated with folliculo-stellate cells (FS cells which lay next to the large colloid containing follicles. This suggests that not only are the FS cells important in the production of the colloids, but the adjacent LH and PRL cells in some way also contribute to their formation.
OBJECTIVE: We recently identified a new protein, pituitary gland specific factor 1a (PGSF1a), that is specifically transcribed in the pituitary gland. In our investigation of anti-PGSF1a antibody for pituitary diseases, we examined it in patients with RA and other autoimmune diseases. We unexpectedly discovered the frequent existence of anti-PGSF1a antibody in patients with RA. We therefore examined the prevalence of this antibody to understand its clinical significance in RA. METHODS: Anti-PGSF1a antibody was detected by radioligand assay using recombinant (35)S-labelled PGSF1a protein. Antibody activity is expressed as an index that was obtained by comparison with normal pooled serum. RESULTS: RA patients had a significantly higher mean anti-PGSF1a antibody index (n=46, 1.28+/-0.38, P < 0.001) than healthy controls (n=36, 1.04+/-0.13). Indices greater than the cut-off value (mean+2 S.D. of healthy controls) were found in 43.5% (20/46) and 10.0% (2/20) of patients with RA and osteoarthritis, respectively. There was no correlation between the activities of anti-PGSF1a antibodies and titres of rheumatoid factor (RF) or serum C-reactive protein concentrations, but RA patients with more erosive disease had a higher mean anti-PGSF1a antibody index. Four of eight sera samples obtained from RF-negative RA patients were positive for anti-PGSF1a antibodies. CONCLUSION: Anti-PGSF1a antibody is a useful new marker for the diagnosis of RA, especially for RF-negative RA, and may relate to clinical manifestations of RA.
The present report describes the activity of aspartate aminopeptidase, in 9 brain areas and in the pituitary gland, during the estrous cycle and several stages of pregnancy of the rat. The quantitation of the enzyme activity was performed by measuring the rate of hydrolysis of the chromogenic substrate Asp-beta-naphthylamide. Aspartate aminopeptidase activity, in the pituitary gland and in several limbic areas, was found to be greater in cyclic than in pregnant rats. However the enzyme activity did not change significantly during either the estrous cycle and pregnancy.
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Clusterin is a glycoprotein known to play various physiological roles including complement activity, amyloid binding activity in Alzheimer disease, as well as binding with heat shock proteins and abnormal prions. The present study immunohistochemically investigated the expression of clusterin in the human pituitary gland in subjects of 10-88 years of age (n=173). Causes of death were blunt injury (n=35), sharp injury (n=15), poisoning (n=11), drowning (n=14), fire fatalities (n=28), asphyxiation (n=15), hypothermia (n=7), hyperthermia (n=3), and natural diseases (n=45). Clusterin was detected in mixed cell follicles and the anterior lobar parenchymal cells. The area occupied by cells positive for clusterin were measured, and the ratio to the whole area of the anterior lobe (% clusterin-positive cell area) was estimated. There was a good correlation between the age of the subjects in years and the % clusterin-positive cell area in the anterior lobe of the pituitary gland (r=0.736, P<0.01). Relationships between % clusterin-positive cell and gender, cause of death, and survival time were insignificant. These findings indicate an age-dependent accumulation of clusterin in the pituitary gland, which may be related to the aging of endocrine systems.