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PubMedDate not supplied

Measurement of pituitary gland height with MR imaging.

From sagittal magnetic resonance (MR) images with 10 mm slice thickness, the mean vertical height of the pituitary gland in 42 normal patients was found to be 5.4 +/- 0.9 mm. Computed tomographic (CT) scans in the coronal plane showed the same. Measurements of pituitary size in 13 patients with tumors using both CT and MR were also essentially equivalent. The ease, comfort, and accuracy of the MR pituitary measurement supports its use as the examination of choice for measuring pituitary height.

Adult↗
PubMed2005

Mouse anterior pituitary gland: analysis by ion trap mass spectrometry.

We investigated the proteome of the anterior pituitary gland (AP) in a species in which the genome has been sequenced. Subcellular fractions of APs from 2-month-old male mice were prepared for protein denaturation, treatment with trypsin and analyses utilizing micro liquid chromatography tandem mass spectrometry and the database search software SEQUEST. In the nuclear, non-nuclear 100,000 g and cytosolic fractions, we identified 49, 36 and 68 different proteins, respectively. A total of 115 distinct proteins were detected. We identified growth hormone, prolactin, pro-opiomelanocortin, the alpha-subunit for the glycoprotein hormones, and luteinizing hormone-beta. Groups of other identified proteins included hormone-processing, secretion granule-associated, non-hormonal endoplasmic reticulum-associated, calcium-binding, protein kinase C-associated, histones, non-histone chromosomal, other RNA-binding, heterogeneous nuclear ribonucleoproteins, splicing factors, helicases, lamins, ribosomal, microtubule-associated, microfilament-associated, adenosine triphosphate- and guanosine triphosphate-associated, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation, enzymes in glycolysis and the tricarboxylic and urea cycles and the pentose phosphate path, heat-shock, glutathione-associated, peroxidases, ubiquitin-associated, catabolic, protease inhibitors, other, and blood proteins. The 115 proteins reported in this study and the 145 proteins reported in a previous study on the AP of the adult male Golden Syrian hamster are compared and form a foundation for defining the proteome in normal adult male AP.

Animals↗
PubMed1990

Evidence for a direct negative effect of estradiol at the level of the pituitary gland in sheep.

The purpose of this experiment was to determine if pituitary stores of LH could be replenished by administration of GnRH when circulating concentrations of both progesterone and estradiol-17 beta (estradiol) were present at levels observed during late gestation. Ten ovariectomized (OVX) ewes were administered estradiol and progesterone via Silastic implants for 69 days. One group of 5 steroid-treated OVX ewes was given GnRH for an additional 42 days (250 ng once every 4 h). Steroid treatment alone reduced (p less than 0.01) the amount of LH in the anterior pituitary gland by 77%. Pulsatile administration of GnRH to steroid-treated ewes resulted in a further decrease (p less than 0.01) in pituitary content of LH. Compared to the OVX ewes, concentrations of mRNAs for alpha- and LH beta-subunits were depressed (p less than 0.01) in all steroid-treated ewes, whether or not they received GnRH. The ability of the dosage of GnRH used to induce release of LH was examined by collecting blood samples for analysis of LH at 15 days and 42 days after GnRH treatment was initiated. Two of 5 and 3 of 5 steroid-treated ewes that received pulses of GnRH responded with increased serum concentrations of LH after GnRH administration during the first and second bleedings, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Transcriptional and posttranscriptional regulation of the proopiomelanocortin gene in the pars intermedia of the pituitary gland of Xenopus laevis.

In the melanotrope cells of the intermediate pituitary gland of the amphibian Xenopus laevis, expression of the POMC gene is under physiological control, i.e. it is 20- to 30-fold higher in animals adapted to a black background compared to animals adapted to a white background. To investigate whether changes in POMC messenger RNA stability contribute to this difference in expression, a steady state kinetic model for mRNA degradation was used to determine the half-life of POMC mRNA during the induction and deinduction of POMC gene expression in melanotrope cells. During induction of the POMC gene the half-life of POMC mRNA was 3- to 4-fold longer than during deinduction. This difference in mRNA stability is, however, not sufficient to account for the 20- to 30-fold difference in the steady state levels of POMC mRNA between the two physiological conditions. Results from experiments with the protein synthesis inhibitor cycloheximide and the mRNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzidimidazole suggest 1) that during induction of POMC gene expression no de novo protein synthesis is required and, 2) that deinduction of POMC gene expression requires transcriptional activation of an mRNA-degradation system. Pulse-labeling experiments with [3H]uridine showed that in neurointermediate lobes of white-adapted animals there is an 8-fold higher amount of newly synthesized POMC mRNA than in lobes of black animals. This suggests a fast in vitro induction of POMC gene transcription. The dopamine D2-receptor agonist apomorphine decreased POMC mRNA biosynthesis about 5-fold, which confirms that regulation of POMC gene expression includes a transcriptional component. In conclusion, our results demonstrate that during the physiological process of background adaptation the regulation of POMC gene expression in Xenopus melanotrope cells is exerted by alterations in POMC gene transcription as well as in POMC mRNA stability.

Animals↗
PubMed1984

Effect of hypothalamic neuropeptides on corticotrophin release from quarters of rat anterior pituitary gland in vitro.

The effect of six hypothalamic peptides on the basal release of ACTH and that induced by arginine vasopressin (AVP) or by ovine corticotrophin releasing factor (oCRF) from fragments of the rat anterior pituitary gland incubated in vitro was investigated. Dose-response curves to AVP and to oCRF were obtained, and the response to a low dose of oCRF was potentiated by a low dose of AVP. Basal release of ACTH was not affected by any of the peptides in concentrations in the range 10(-12) to 10(-6) mol/l, and only substance P (SP) and somatostatin (SRIF) inhibited significantly the response to oCRF in a dose-related manner. The responses to a range of doses of oCRF or AVP were reduced by 10(-8) and 10(-6) mol SP or SRIF/l, and to a greater extent by the higher dose. Except in the case of 10(-6) mol SRIF/l on the response to AVP, the response was not further diminished by preincubation of the tissue with the peptide before the stimulating agent was added. The inhibition of the responses to AVP or oCRF by 10(-9) mol SP/l was not potentiated by its combination with either 5 X 10(-10) or 10(-8) mol SRIF/l; the inhibitory effects were merely additive. The results suggest that although SRIF and SP are able to modulate the release of ACTH from the anterior pituitary gland, they do so only at a high concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed2005

Proteomics of the anterior pituitary gland as a model for studying the physiology of a heterogeneous organ.

The anterior pituitary gland (AP) secretes six established hormones that collectively control hundreds of biological and behavioral functions. Because of advances in mass spectrometry (MS), protein labeling, and bioinformatics, it is now possible to characterize, compare, and quantify the AP hormones together with large numbers of nonhormonal AP proteins. For example, by using high-performance liquid chromatography in line with tandem MS we characterized 145 proteins in sub-cellular fractions of the AP of young adult male Golden Syrian hamsters and 115 proteins in subcellular fractions of the AP of young adult male mice. These included hormones, proteins involved in hormone synthesis and release, and housekeeping proteins. We also used difference gel electrophoresis in conjunction with MS and peptide mass fingerprinting to quantify the effects of estrogen on the AP-soluble protein fraction in rats. Ovariectomized rats were administered 50 microg of estradiol valerate subcutaneously and studied 48 hrs later, before the onset of the anticipated surges of gonadotropins in blood. Following DeCyder image analysis, we identified by MS and peptide mass fingerprinting 26 protein spots that were upregulated and 19 protein spots that were downregulated. Estrogen increased levels of acidic isoforms of growth hormone and prolactin, several proteins involved in protein synthesis, folding and secretion, and several metabolic enzymes. Most of the downregulated proteins are involved in RNA or DNA interactions. We followed up on the results with RT-PCR and immunohistochemical techniques to demonstrate that one protein identified by MS in hamster AP, fertility protein SP22, is synthesized in the AP and localized primarily in somatotropes and thyrotropes. These experiments demonstrate the efficacy of our proteomics approach to characterize AP proteins and quantify changes in them. The approaches used to study the AP could serve as a model to investigate other heterogeneous organs.

Animals↗
PubMed1979

Thyrotrophs in old age. An immunocytologic study of human pituitary glands.

In order to reveal whether thyrotroph cells of the human pituitary are affected by aging, a histologic and immunocytologic study was undertaken on the pituitaries of patients over 80 years of age (10 men, 10 women), dying of various acute illnesses and the findings compared with those of a younger age group (10 men, 10 women), dying of various acute illnesses between the age of 20-56 years. The incidence, distribution, granulation, cytoplasmic vacuolization, as well as immunoreactivity of TSH cells, showed no major differences related to age and sex. Lack of involution of thyrotroph cells in old subjects indicates that the pituitary is capable of producing TSH with advancing age.

Adult↗
PubMed1985

Heterogeneity of adrenocorticotrophin in the pituitary gland and plasma during the perinatal period.

Three immunoreactive forms of ACTH are characterized by their apparent molecular weight (MW) and bioactivity when acid extracts of the anterior or of the neurointermediate lobe of fetal and newborn rat pituitary glands are subjected to gel filtration on Sephadex G50 fine columns. The "big" ACTH form which shows an apparent MW close to 44 000 hardly stimulates the in vitro release of corticosterone by perifused fetal adrenals. In contrast, the "intermediate" (MW: congruent to 13 000) and "little" (MW: congruent to 4 500) forms show high biological activity by eliciting corticosterone secretion which is log-dose-dependent. During the perinatal period, the relative proportions between these different molecular forms of ACTH change in both the anterior and neurointermediate lobes. "Big" ACTH is the main form in the neurointermediate lobe of the fetal rat pituitary. After birth, the "big" ACTH/total ACTH ratio regularly decreases until postpartum week 4; it is not very different then from that of pregnant adult females. The three immunoreactive forms of ACTH are present in the anterior lobe throughout the perinatal period. The gradual increase of the "intermediate" and "little" forms is accompanied by a correlative decrease in the "big" form. The anterior lobes of 17, 19 and 21-day old fetuses, stimulated in vitro by an acid extract of adult hypothalamus, release the three immunoreactive forms of ACTH in the same proportions as those observed in corresponding extracts of anterior lobes. On days 17, 19 and 21 of gestation, fetal plasma contains all the immunoreactive forms of ACTH previously observed in pituitary glands. The proportion of the "little" ACTH form gradually increases, whereas that of the "big" form decreases as gestation progresses. At term, the relative proportion of "little" ACTH is greater in the plasma than in the fetal pituitary. Controlled trypsic digestion of pituitary "big" ACTH results in a conversion to the "intermediate" and "little" immunoreactive forms. When "intermediate" ACTH is submitted to tryptic digestion under the same conditions, there is continuous loss of immunoreactivity but no change of hormonal form. These findings strengthen the hypothesis that "big" ACTH is a precursor of "intermediate" and "little" ACTH; in contrast, the "intermediate" form is not a precursor of the "little" one. The high molecular-weight form of ACTH might be converted endogenously into lower MW forms in the fetal circulation at term as well as in newborns. In fetal plasma, immunoreactive ACTH levels reach peak values on day 19 of gestation and decrease thereafter until day 21.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropic Hormone↗
PubMed1980

Remission of pituitary-dependent Cushing's disease after removal of nonneoplastyic pituitary gland.

Transsphenoidal hypophysectomy was performed on a 28-year-old woman with pituitary-dependent Cushing's disease. Both clinical and chemical resolution of the hypercortisolism was achieved in spite of no evident pituitary microadenoma or cell hyperplasia. Histologic examination revealed widespread Crooke's changes and normal relative numbers, size, and distribution of corticotrophs. We propose that rare patients with pituitary-dependent Cushing's disease may have excessive pituitary production of adrenocorticotropic hormone in the absence of an adenoma or corticotroph cell hyperplasia.

Adrenocorticotropic Hormone↗
PubMed1998

Distribution and characterization of the cell types expressing GALR2 mRNA in brain and pituitary gland.

The neuropeptide galanin mediates its activities through G-protein-coupled receptors, and three receptor subtypes have been described with distinctly different patterns of regional tissue expression. GALR1 is predominantly expressed in basal forebrain, hypothalamus, as well as spinal cord. GALR2 has a wider distribution in brain and is also present in the pituitary gland and peripheral tissues. GALR3 has been found to be widely distributed at low abundance. We examined the distribution of GALR2 in rat brain and pituitary by in situ hybridization histochemistry and found it abundant in regions of hippocampus, piriform and entorhinal cortex, basal nucleus of the accessory olfactory tract, amygdala, hypothalamic nuclei, Purkinje cells, and discrete brainstem nuclei. It is also highly expressed in the intermediate and anterior lobes of the pituitary. Using combined in situ hybridization immunohistochemistry we characterized the neurotransmitter and hormonal phenotype of cells expressing GALR2 mRNA in the hypothalamus and pituitary gland. Our findings suggest GALR2 is a receptor mediating important functions of galanin in the hypothalamic-pituitary axis and may also play a role in hippocampal and cerebellar function.

Animals↗
PubMed1984

Interactions of methylestrogens with cytoplasmic and nuclear estrogen receptors in rat pituitary gland, hypothalamus and uterus.

The in vitro affinities to cytoplasmic estrogen receptors of the methylestrogens 2-methylestradiol-17 beta, 4-methylestradiol-17 beta and 4-hydroxy-2-methylestradiol-17 beta, which are useful probes to test the biological importance of 2- or 4-hydroxylation of estradiol-17 beta (catecholestrogen formation), have been determined in hypothalamic, pituitary and uterine tissue of the ovariectomized rat. Moreover, the in vivo capacity of these compounds to translocate estrogen receptors into the cell nucleus of pituitary and uterine tissue has been studied. Methylestrogens exhibited estrogen receptor affinities which were not significantly different from the binding affinity of estradiol-17 beta. When given at a high dose (100 micrograms/animal) their nuclear translocation capacity was equal (4-methylestradiol-17 beta) or even higher (2-methylestradiol-17 beta) than that of estradiol-17 beta. However, at a low dose (5 micrograms/animal) 4-methylestradiol was completely ineffective in both the pituitary gland and the uterus, and 2-methylestradiol-17 beta was less potent than estradiol-17 beta in the pituitary gland.

Animals↗
PubMed1995

Oxytocin and the anterior pituitary gland.

Release of oxytocin into the vicinity of the long portal vessels connecting the hypothalamus with the anterior pituitary gland and the presence of short portal vessels connecting the posterior lobe to the anterior pituitary established the potential for the peptide to act in a neuroendocrine fashion controlling the release of one or several adenohypophyseal hormones. Indeed, oxytocin receptors are present in the gland and numerous trophic effects of the peptide have been described, some with apparent physiological relevance. Thus under defined physiologic conditions a participatory role for oxytocin in the physiologic regulation of at least two hormones, prolactin and adrenocorticotropin, has been evidenced and there is developing credence to the concept that oxytocin may indirectly control gonadotroph function as well. Most recently, novel technologies have identified subpopulations of oxytocin receptive cells within a given cell type in the anterior pituitary gland and the concept of a modulatory effect of the nonapeptide on primary regulatory events has arisen.

Adrenocorticotropic Hormone↗
PubMed1985

Involvement of calcium in the release of immunoreactive beta-endorphin-like peptide from dispersed cells of the neurointermediate lobe of the rat pituitary gland.

The presence of Ca2+ in the incubation medium was required for stimulation of the release of the immunoreactive beta-endorphin-like peptide (IR-beta-EP) from the dispersed cells of the neurointermediate lobe of rat pituitary gland by adenosine 3',5'-monophosphate (cAMP) analogs, a phosphodiesterase inhibitor, L-isoproterenol, cholera toxin and forskolin. The basal release observed in the absence of the stimulants was also dependent on the addition of Ca2+. A calcium antagonist (verapamil) inhibited the effects of the stimulants. A calcium ionophore (A23187) enhanced the release of IR-beta-EP, but did not stimulate the formation of cAMP. These findings suggest that Ca2+ has the essential role in the release of beta-endorphin from the neurointermediate lobe of rat pituitary gland.

1-Methyl-3-isobutylxanthine↗
PubMed1987

A selective extraction of growth hormone from bovine pituitary gland and its further purification and crystallization.

A highly efficient method for the isolation of bovine growth hormone (GH) is described. The method is based on selective extraction of GH from 15,000 g subcellular sediment of anterior pituitary gland with 130-150 mM NH4HCO3, 1 mM EGTA, pH 7.2-7.4, at 2-6 degrees C for 60 min, purification of the extracted GH by ammonium sulfate fractionation, one-step ion-exchange column chromatography on DEAE-cellulose (or CM-cellulose), and gel filtration on Sephadex G-75. This 2-3 day procedure provides a highly pure hormone in high yield (up to 70-80 mg per 35-40 g of the whole pituitary gland), which can be crystallized by the batch method at a low ionic strength and isoelectric pH.

Ammonium Sulfate↗
PubMed1997

Vitamin D receptor gene expression in human pituitary gland.

1,25-dihydroxyvitamin D3 has important physiological effects such as calcium transport and cell growth and differentiation. These biological effects are mediated by their binding to specific intracellular receptor termed vitamin D receptor (VDR). VDR mRNA expression has been demonstrated in several tissues, but to date, there is no information about its presence in the human pituitary gland. In this report, we demonstrate VDR mRNA expression using the reverse transcription-polymerase chain reaction (RT-PCR), as well as the cellular expression of VDR by immunohistochemistry, both in the human pituitary gland. These results suggest the possibility that, like in the rat pituitary, VDR may regulate the human pituitary gene expression and hormone secretion.

Adult↗
PubMed1983

Arterial blood supply of the normal human pituitary gland. An anatomical study.

A technique for the removal of sphenoid blocks from cadavers and for selective injection of the hypophyseal arteries of these specimens is described. Results of such injections are presented, with emphasis on the role of the inferior hypophyseal artery (IHA). The IHA was found to be the most important artery supplying the pituitary gland, and in particular, the structures involved in production, transportation, and storage of the antidiuretic hormone. The literature pertinent to the arterial blood supply of the normal pituitary gland is reviewed.

Arteries↗
PubMed1985

The identification and characterization of alpha-N-acetylated beta-endorphin in the human pituitary gland.

By using a radioimmunoassay specific for alpha-N-acetyl beta-endorphin and its C-terminally shortened forms, we have established the presence of immunoreactive alpha-N-acetyl endorphin (irNacEP) in extracts of five postmortem human pituitary glands (2.27 +/- 0.64 ng/gland). This immunoreactivity has been further characterized by subjecting these extracts to reverse-phase high-performance liquid chromatography (RP-HPLC). In all cases the major peaks of irNacEP co-migrated with synthetic human standard alpha-N-acetyl alpha-endorphin (Nac alpha EP), alpha-N-acetyl gamma-endorphin (Nac gamma EP) and Nac beta EP. These studies thus represent the initial demonstration that alpha-N-acetylation of beta-endorphin and its shorter molecular forms occurs in the human pituitary gland.

Acetylation↗