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At least 469 records · Page 26Linked to original sources
PubMed2000

Immunoreactive pit-1 protein in hyperplastic pars intermedia induced by calcitonin of the rat pituitary gland.

To elucidate the effects of synthetic salmon calcitonin (sCT) on the cells in the rat pituitary gland, we histopathologically and immunohistochemically examined the early changes after 4 or 13 weeks treatment with sCT 120 IU/kg. Focal proliferative lesions of the anterior pituitary glands were consistently found after treatment with sCT for 13 weeks. Histologically, the cells with the focal proliferative lesions were classified into the following three groups: 1) enlarged basophilic cell focus, 2) vacuolated cell focus and 3) chromophobe cell focus. These focal proliferative lesions had positive staining only for the alpha-subunit and failed to show Pit-1 protein immunoreactivity. The sCT treatment also increased the thickness of the pars intermedia. Hypertrophy of the pars intermediate cells was characteristically seen. Furthermore, Pit-1 protein immunoreactivity was clearly detected in the nuclei of the hyperplastic pars intermediate cells. All pars intermediate cells were equally stained by alpha- or beta-MSH and beta-endorphin in both vehicle- and sCT-treatment. No difference was seen. These findings strongly suggest a very close relationship between Pit-1 protein immunoreactivity and cellular proliferation induced by sCT.

Animals↗
PubMed2003

Transgenic studies on the regulation of the anterior pituitary gland function by the hypothalamus.

The anterior pituitary gland is composed of five different cell types secreting hormones whose functions include the regulation of post-natal growth (growth hormone, GH), lactation (prolactin, PRL), reproduction (luteinising hormone, LH, and follicle stimulating hormone, FSH), metabolism (thyroid stimulating hormone, TSH), and stress (adrenocorticotrophic hormone, ACTH). The synthesis and secretion of the anterior pituitary hormones is under the control of neuropeptides released from the hypothalamus into a capillary portal plexus which flows through the external zone of the median eminence to the anterior lobe. This review describes the ways that gene transfer technologies have been applied to whole animals in order to study the regulation of anterior pituitary function by the hypothalamus. The extensive studies on these neuronal systems, within the context of the physiological integrity of the intact organism, not only exemplify the successful application of transgenic technologies to neuroendocrine systems, but also illustrate the problems that have been encountered, and the challenges that lie ahead.

Animals↗
PubMed2006

Development of a real-time (Q) PCR assay to measure variation in expression of prolactin receptor mRNA in the hypothalamus and pituitary gland during late embryogenesis in turkeys and chickens.

Changes in levels of PRLR mRNA in the pituitary gland and hypothalamus of chickens and turkeys from embryonic day (ED) 15 and ED21 to 1 day post-hatch, respectively, were measured by real-time PCR. In both species, PRLR mRNA increased from low levels during the last week of ED to reach maxima at the peri-hatch period. Similarly, circulating levels of PRL also increased during this interval and were highly correlated with levels of the PRLR mRNA in both the pituitary gland and hypothalamus. This suggests that PRL was up-regulating its receptor. In support of this, stimulation of the turkey pituitary gland with VIP on ED24 resulted in a 4- and 3-fold increase in PRL and PRLR, respectively. Since VIP had no direct effect on the levels of PRLR transcript in the hypothalamus, it is likely that VIP is acting indirectly through increased PRL to up-regulate the number of receptors.

Animals↗
PubMedDate not supplied

Magnetic susceptibility artifact in spin-echo MR imaging of the pituitary gland.

PURPOSE: To evaluate the magnetic susceptibility effect on spin-echo MR images of the pituitary gland. METHODS: Air-in-water phantom experiments and studies in normal volunteers were performed using various sampling bandwidth (8.3-33.3 kHz) spin-echo sequences with the polarity of the readout gradient normal or reversed. RESULTS: Attachment of a sphenoid septum to the sellar floor was the major factor in the appearance of the inferior surface of the pituitary gland. Patterns of distortion and/or artifactual signal intensities, related to the presence or absence of the attachment, were accentuated on the images with narrower bandwidth. A "spearhead shape" deformity of the sphenoid sinus was observed both in the air-in-water phantom experiment, and when no sphenoid septum was present. When a sphenoid septum was present, two spearhead shapes side by side were present. High-intensity artifacts were seen where the sellar floor was misplaced into the pituitary gland. CONCLUSION: Knowledge of the patterns of distortion and high-intensity artifact is important in the diagnosis of pituitary lesions.

Adult↗
PubMed2002

Microadenomas of the pituitary gland in children with and without hypophyseal dysfunction in magnetic resonance imaging.

The aim of this study was to correlate lesions of the pituitary gland with hormonal dysregulation. The hormonal status of 63 children was correlated with MRI findings of the pituitary gland. Two radiologists judged the MRI examinations without knowledge of the hormonal situation. The reliability of the diagnosis "adenoma" was evaluated in five steps from 0-100% for each sequence. A microadenoma was found in six of 14 children with hyperprolactinemia and in six of eight patients with increased IGF-I/IGFBP-3. However, microadenomas were also detected in eight of 28 children without hormonal dysfunction (clinical feature: obesity). The adenomas were seen best in a dynamic sequence after gadolinium administration. An expansive growing macroadenoma was found in one of 13 patients with hypopituitarism. We found a relatively high number of microadenomas even in children without any hormonal dysfunction. Taking into account the reported autopsy results (6.1-27% occult microadenomas), we suggest that the MRI diagnosis "microadenoma" is made too frequently if usual MRI criteria are used. Patients with increased levels of IGF-I/IGFBP-3 had a high incidence of microadenoma (up to 87.5%). Hyperprolactinemia was associated with microadenomas in about 43% (-57%) of patients (nearly on the same level as children without hormonal dysfunction). Therefore unspecific stimulation of the pituitary gland with consecutive increased volume seems to be responsible for hyperprolactinemia in many of these patients.

Adenoma↗
PubMed1978

Changes in oestradiol-17beta binding in the hypothalami and pituitary glands of persistently infertile ewes previously exposed to oestrogenic subterranean clover: evidence of alterations to oestradiol receptors.

The binding of [3H]oestradiol-17beta to the hypothalamus and pituitary gland of clover-affected permanently infertile and control ovariectomized ewes was compared in vivo and in vitro. When [3H]oestradiol-17beta was infused into the carotid artery (10 ng/min), the total homogenate and the nuclear and protamine-precipitable cytosol fractions of hypothalami and pituitary glands from clover-affected ewes bound significantly more[3H]oestradiol than those of the controls. Cytoplasmic oestradiol-17beta receptors from the pituitary glands of clover-affected ewes showed a significantly lower apparent association constant and a higher number of binding sites/mg protein in vitro. It is suggested that the hypothalami and pituitary glands of ewes made permanently infertile by oestrogenic clover are less sensitive to feedback regulation of oestradiol-17beta at physiological levels.

Animals↗
PubMed2005

Dynamic MR imaging for diagnosis of lesions adjacent to pituitary gland.

In this study, we evaluated the usefulness of dynamic studies for the preoperative diagnosis of tumor lesions adjacent to the pituitary gland. We examined 13 tumors. We obtained pre- and post-contrast thin slice T1-weighted images of the sellar regions. FSE sequences were used for dynamic study. The capability to distinguish the tumor from the pituitary gland and additional information obtained from the dynamic study were evaluated. Two meningiomas were identified more clearly on the dynamic than on the delayed study. In two cavernous hemangiomas, the peripheral nodular stains gradually increased during the dynamic study. For the preoperative evaluation of lesions adjacent to the pituitary gland, the dynamic study can often identify the lesions more clearly and may provide additional information.

Adult↗
PubMed2003

The regional oxygen saturation of pituitary adenomas is lower than that of the pituitary gland: microspectrophotometric study with potential clinical implications.

OBJECTIVE: To study the regional oxygen saturation (rSO(2)) of pituitary adenomas, in comparison with that of the pituitary gland. METHODS: Microspectrophotometric (MSP) measurements of rSO(2) in adenomas and pituitary tissue were performed for a series of patients undergoing first-time transsphenoidal pituitary adenoma surgery, in a standardized anesthesia setting. The areas of measured tissue were sampled for histopathological and immunohistochemical (CD34 and CD45) assessments. The results of MSP measurements were compared with the results of the histopathological and immunohistochemical assessments. RESULTS: Thirty-six MSP measurements and tissue samples were obtained among 22 patients with pituitary macroadenomas, including 14 from adenoma tissue, 17 from the anterior pituitary lobe, and 5 from the posterior pituitary lobe. The rSO(2) of adenoma tissue (mean +/- standard deviation, 43.3 +/- 23.2%) was statistically significantly (P = 0.001) lower than the values for the anterior pituitary lobe (mean +/- standard deviation, 71.8 +/- 18.3%) and posterior pituitary lobe (mean +/- standard deviation, 74.9 +/- 4.8%). The difference between the rSO(2) values for the anterior pituitary lobe and posterior pituitary lobe was not significant. There were no statistically significant differences in microvessel density (as assessed with CD34 staining) or lymphocyte density (as assessed with CD45 staining) among the three tissue types. CONCLUSION: As assessed with MSP measurements, the rSO(2) of adenoma tissue was significantly lower than that of the pituitary gland, indicating differences in their blood supply and/or metabolism in pituitary macroadenomas. Further studies are needed to determine whether MSP measurements can reliably facilitate intraoperative delineation of adenoma and pituitary tissue, in the effort to achieve complete tumor removal with minimal injury to pituitary tissue.

Adenoma↗
PubMed1989

Cell type heterogeneity of intermediate filament expression in epithelia of the human pituitary gland.

In the present study we have localized immunohistochemically the intermediate filament proteins of the human pituitary gland (adenohypophysis, pars intermedia and pars tuberalis) by an indirect immunoperoxidase technique or by double immunofluorescence methods and analysed the individual cytokeratin polypeptides using two-dimensional gel electrophoresis. We found that the expression of cytokeratins in different epithelial cells of the human anterior pituitary gland was heterogeneous. Whereas the endocrine cells only expressed cytokeratins 8 and 18, the folliculo-stellate cells exhibited a reactivity for cytokeratins 7, 8, 18 and 19 as well as for GFAP and vimentin. The squamous epithelial cells of the pars tuberalis and the Ratke's cysts showed a more complex cytokeratin pattern of both squamous and simple type. Whereas in may cystic epithelial cells including the "pseudo-follicles" a triple expression of cytokeratin, vimentin and GFAP could be observed, only some basal cells of squamous epithelial nests coexpressed cytokeratin and vimentin. The differences in the intermediate filament protein distribution are discussed in the light of embryological relationships of the different parts of the human pituitary gland.

Desmin↗
PubMed1981

Hypernephroma metastasis in the pituitary gland. A case report.

In a 59-year-old man with a hypernephroma tumour of the right kidney, a metastasis in the pituitary gland of this neoplasm was diagnosed 9 years after removal of the kidney. However, metastases were also found in the left kidney. It cannot be established whether the metastasis in the pituitary gland came form the original tumour or from the other diseased kidney. To the best knowledge, a hypernephroma metastasis to the pituitary gland has not been reported previously.

Adenocarcinoma↗
PubMed1997

Role of neuropeptides and amino acids in controlling secretion of hormones from the anterior pituitary gland in pigs.

All reproductive processes involve one or more of the protein hormones secreted from the anterior pituitary gland: LH, FSH, prolactin, growth hormone, ACTH and thyroid-stimulating hormone (TSH). Primary hormones of reproduction, such as LH and FSH, directly regulate a reproductive activity. For example, LH and FSH stimulate follicular growth and the associated secretion of oestradiol in sows. In contrast, secondary hormones of reproduction such as TSH are permissive and regulate other physiological systems that indirectly, but profoundly, influence reproduction. Reproduction in pigs can be enhanced by developing strategies to alter and control secretion of hormones from the anterior pituitary gland. However, the successful manipulation of adenohypophysial hormone secretion will require a sound understanding of the mechanisms controlling the function of the hypothalamic-pituitary axis. Hypothalamic hormones including GnRH, dopamine, growth hormone-releasing hormone (GHRH), somatostatin, corticotrophin-releasing hormone (CRH) and thyrotrophin-releasing hormone (TRH) are synthesized in perikarya that possess axons that terminate at the median eminence. These hormones are released into the hypothalamo-hypophysial portal vasculature, travel to the anterior pituitary gland and stimulate or inhibit secretion of adenohypophysial hormones. Secretion of hypothalamic hormones is ultimately controlled by a variety of neurotransmitters and neuropeptides, the most studied in swine being the endogenous opioid peptides (EOP) and more recently, the excitatory amino acids (ExAA). In general, EOP inhibit GnRH and hence LH secretion, and this effect involves the central catecholaminergic system. A definitive role for EOP in the modulation of FSH release remains to be determined. EOP stimulate secretion of GHRH and thus growth hormone release, and depending on the animal model studied, EOP exert either stimulatory or inhibitory influences on prolactin secretion. ExAA, working via N-methyl-D-aspartate (NMDA) receptors at the central nervous system, stimulate secretion of LH, FSH, growth hormone and prolactin in appropriate animal models. However, in certain situations, an inhibitory effect of ExAA on LH secretion has been demonstrated. The modulation of growth hormone and prolactin secretion by ExAA involves EOP. Research investigating the function of ExAA and EOP in the physiological control of swine reproduction warrants further scrutiny.

Animals↗
PubMed2004

Evaluation of anterior pituitary gland volume in childhood using three-dimensional MRI.

BACKGROUND: Three-dimensional MRI (3D-MRI) is a reliable tool for the evaluation of anatomical volumes. Volumetric measurement of the normal anterior pituitary gland in childhood has been performed in the past by 2D-MRI calculations, but has inherent inaccuracies. OBJECTIVE: To obtain accurate normal anterior pituitary gland volume in childhood using 3D-MRI coronal sections. MATERIALS AND METHODS: The anterior pituitary gland was measured using coronal T1-weighted 3D-gradient-echo sequences (section thickness 0.75 mm). The study group was composed of 95 prepubertal children (age range 2 months-10 years) with clinically normal pituitary function and no pituitary or brain abnormalities. RESULTS: A measurement error of 0.2-0.4% was assessed by using a phantom study. Volumetric evaluation of the anterior pituitary gland showed progressive growth of the gland from a mean 131+/-24 mm(3) at 2-12 months, to 249+/-25 mm(3) at 1-4 years and 271+/-29 mm(3) at 5-10 years. CONCLUSIONS: These data may be useful for paediatricians in the evaluation of patients with neuroendocrine diseases, in particular growth hormone deficiency.

Analysis of Variance↗
PubMed1995

Molecular cloning and expression of a pituitary gland protein modulating intestinal fluid secretion.

Antisecretory factor (AF) is a protein known to inhibit intestinal fluid secretion induced by cholera toxin. cDNA clones, expressing immunoreactivity to AF were isolated from a human pituitary gland library and sequenced. The sequence contained 1309 base pairs plus a poly(A) tail; Northern blot analysis of pituitary RNA confirmed this size. One large open reading frame was found to code for 382 amino acids. The protein was expressed in pGEX-lambda 1T/Escherichia coli and purified. The recombinant AF was extremely potent, 9 ng (2.10(-13) mol), giving a significant antisecretory activity against cholera toxin-induced fluid secretion in rat. Antiserum against recombinant AF was used in immunohistochemical and Western blot analysis. Sections from human pituitary glands manifested specific intracellular staining in cells exclusively located in the anterior part. Both recombinant AF and AF extracted from pituitary gland appeared in SDS-polyacrylamide to have a molecular mass of 60 kDa, although the renal value was 41 kDa. The protein sequence manifested homology (29% identity) with one protein, a putative Saccharomyces cerevisiae 30-kDa protein of unknown function.

Amino Acid Sequence↗
PubMed1996

Pituitary gland receives both central and peripheral neuropeptide Y innervation.

Neuropeptide Y (NPY)-containing neural projections to the rat pituitary gland were studied by combining NPY immunohistochemistry with retrograde tracing with Fluorogold as well as central and peripheral denervations. Numerous pituitary-projecting, i.e. Fluorogold-labelled, neurons in the superior cervical ganglion, as well as in the hypothalamic magnocellular nuclei were NPY-immunoreactive (NPY-IR). In contrast, no other hypothalamic NPY-IR neurons, e.g. in the arcuate nucleus or the preoptic area, were observed to be projecting into the pituitary. Within the posterior lobe of the pituitary gland two morphologically distinct NPY-IR fiber populations were discovered, namely thinner parenchymal terminals, distinct from the neurosecretory terminals, and thicker, perivascular fibers. Neurosecretory nerve terminals, in contrast, were devoid of NPY-IR, being consistent with the previous reports on their sensitivity to osmotic stimulation. On the other hand, the anterior and intermediate lobes contained no NPY-IR fibers. Bilateral extirpation of the superior cervical ganglion resulted in disappearance of the perivascular NPY-IR fibers leaving the parenchymal NPY-IR fibers unaffected, while transection of the pituitary stalk abolished all of the parenchymal NPY-IR neurons, leaving the perivascular fibers unaffected. These findings together with the observed colocalization of tyrosine hydroxylase and NPY in the posterior lobe perivascular fibers indicated that they are sympathetic nerve endings. The thin parenchymal terminals, instead, are suggested to stem from central sources other than hypothalamus. Our findings indicate that the pituitary gland receives NPY-containing innervation from at least three distinct sources, and NPY may thus affect pituitary functions in various ways, such as blood flow and vasopressin release.

Animals↗
PubMed1986

Blood flow in diethylstilbestrol-induced anterior pituitary gland hyperplasia.

Anterior pituitary hyperplasia was developed in female Fisher 344 rats by subcutaneously implanted slow-release diethylstilbestrol (DES) capsules. Blood flow was measured in two separate areas of the adenohypophysis using hydrogen clearance method at 6, 9, 10, and 13 weeks after the implantation. Blood flow progressively decreased while the DES capsules were in place (normal values in ml/g/min, mean +/- SD: 0.93 +/- .12 laterally and 1.15 +/- .11 medially, decreasing to 0.25 +/- .07 and 0.24 +/- .07, respectively, by 13 weeks). Histology confirmed nodular hyperplasia, development of large vascular lakes, and hemorrhages within the adenohypophysis. Total adenohypophysial blood flow was calculated as a product of mean blood flow as measured per unit weight and the weight of the gland. This figure progressively increased from 12.7 +/- 2 to 22.2 +/- 8 microliter/min by 13 weeks. All these changes were significant at the P less than 0.001 level. These blood flow measurements suggest that the hyperplastic adenohypophysis outgrows its blood supply which is additionally compromised by "useless" pooling of blood in the vascular lakes. However, there is an overall increase in the amount of blood flowing through the hyperplastic gland which may be explained by newly formed supplying vessels.

Animals↗
PubMed1985

Ultrastructural immunocytochemistry of gonadotrophs in the goldfish pituitary gland.

The immunocytochemical distribution of gonadotropin (GTH) in the goldfish pituitary gland was studied applying the peroxidase-antiperoxidase (PAP) method and the protein A-gold technique at light- and electron-microscopic levels, respectively, with an antiserum raised against silver carp GTH. In the light-microscopic immunocytochemistry, PAS-positive cells in the proximal pars distalis showed strong reaction with the antiserum. Gold particles wee concentrated both on globules (large) and on granules (small) of the gonadotrophs (PAS-positive cells) in the electron-microscopic immunocytochemistry. Other cells in the pituitary gland, including thyrotrophs, displayed no immunoreactivity with the antiserum at the dilutions tested. These results indicate, not only immunocytochemical distribution of GTH both in globules and in granules in the gonadotrophs, but also the high purity of the antigen (silver carp GTH) and specificity of the antiserum.

Animals↗
PubMed1988

Immunohistochemical localization of gamma-aminobutyric acid in the rat pituitary gland and related hypothalamic regions.

The distribution of gamma-aminobutyric acid (GABA) containing neurons in the rat pituitary gland and related hypothalamic areas was immunohistochemically investigated using antibodies raised against GABA conjugated to bovine serum albumin by glutaraldehyde. A dense network of GABA-like immunoreactive fine varicose nerve fibers was observed within the posterior and intermediate lobes of the pituitary gland, surrounding endocrine cells and capillaries, but not in the anterior lobe. In the pituitary stalk, the dense varicose fibers ran along the anterior wall of the posterior lobe into the posterior and intermediate lobes. A small number of GABA-like immunoreactive cell bodies were evident in the intermediate lobe. GABA-like immunoreactive fibers occurred at low to high density in most parts of the hypothalamus. GABA-like immunoreactive neurons were observed in some regions related to the pituitary gland (such as periventricular nucleus, paraventricular nucleus, arcuate nucleus and accessory magnocellular nucleus). These results provide morphological evidence for the presence of GABAergic neurons in the rat hypothalamo-pituitary system.

Animals↗