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At least 523 records · Page 29Linked to original sources
PubMed1992

Expression of the growth hormone receptor gene in chicken pituitary glands.

Although GH has no direct effect on GH release from chicken pituitary glands, GH receptor mRNA similar to that in the rabbit liver was identified by Northern blot analysis in extracts of adult chicken pituitaries. Complementary (c) DNA, reverse transcribed from chicken pituitary RNA, was amplified by the polymerase chain reaction (PCR) in the presence of 3'- and 5'-oligonucleotide primers coding for the extracellular domain of the chicken liver GH receptor and was found to contain an electrophoretically separable fragment of 500 bp, identical in size to that in chicken liver. Digestion of this pituitary cDNA with NcoI produced expected moities of 350 and 150 bp. Amplification of chicken pituitary cDNA in the presence of oligonucleotide primers for the intracellular sequence of the chicken liver GH receptor produced an electrophoretically separable fragment of approximately 800 bp, similar to that in chicken liver. This fragment was cut into expected moieties of 530 and 275 bp after digestion with EcoRI. These PCR fragments were identified in extracts of the pituitary caudal lobe, in which somatotrophs are confined and account for the majority of endocrine cell types, and in the cephalic lobe, in which somatotrophs are lacking. Translation of the GH receptor mRNA in the pituitary gland was indicated by the qualitative demonstration of radiolabelled GH-binding sites in plasma membrane preparations, in pituitary cytosol and in nuclear membranes. These results provide evidence for the expression and translation of the GH receptor gene in pituitary tissue, in which GH receptors appear to be widely distributed within cells and in different cell types. GH may therefore have paracrine, autocrine or intracrine effects on pituitary function.

Animals↗
PubMed1982

Peptides derived from pro-opiocortin in the pituitary gland of the dogfish, Squalus acanthias.

Combined rostral, median and neurointermediate lobes from 650 pituitary glands of the dogfish Squalus acanthias were extracted in 0.1 M-HCl and subjected to filtration on Sephadex G-50. Fractions were monitored for ACTH, alpha-MSH, gamma-MSH and endorphin by heterologous radioimmunoassay, corticotrophin-like intermediate lobe peptide (CLIP) and gamma-MSH by homologous radioimmunoassay, and methionine enkephalin after enzymatic digestion. The majority (about 99%) of the immunoreactivity detected was present as small peptides, with alpha-MSH, CLIP and gamma-MSH predominant. The single peaks of ACTH, alpha-MSH and CLIP contrasted with many distinct peaks of endorphin-like immunoreactivity. The gamma-MSH radioimmunoassays monitored different peptides; the heterologous assay revealed a single major peak, while the homologous assay detected a number of distinct small peptides. The results suggested that there may be more than three distinct forms of MSH in the dogfish pituitary gland. Small amounts of much larger proteins were detected by a number of the radioimmunoassays, suggesting that peptides related to ACTH, gamma-MSH and lipotrophin are derived from common pro-opiocortin-type precursor molecules in this phylogenetically ancient cartilaginous fish.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Prolactin content of the pituitary gland in response to hypertonic saline medium, antithyroid drugs, methallibure and thyroxine in a freshwater teleost Heteropneustes fossilis.

Variations in the prolactin content of the pituitary gland in response to different treatments were studied in a freshwater catfish, H. fossilis. One week of saline (1% NaCl medium) treatment reduced the pituitary prolactin content but enhanced the serum prolactin level showing release of prolactin from the pituitary gland. Two weeks of saline treatment reduced pituitary as well as serum prolactin content presumably a result of reduced prolactin synthesis in the pituitary gland. This reduction of synthetic activity in this species is probably due to a drop in prolactin requirement. All the antithyroid durgs tested as well as L-thyroxine decreased the pituitary prolactin content. Methallibure administration induced the release of prolactin from the pituitary as evidenced by the lowered prolactin level in this gland and a simultaneous increase in the prolactin content of the serum.

Animals↗
PubMed1982

Angiotensin-converting enzyme in discrete areas of the rat forebrain and pituitary gland.

With the use of a sensitive radioisotopic method we have examined the activity of the angiotensin-converting enzyme (ACE, E.C. 3.4.15.1) in specific nuclei of the rat forebrain and in the anterior, intermediate and posterior lobes of the pituitary gland of the rat. We reported that ACE activity is heterogeneously distributed in the rat forebrain, with a 200-fold difference between the lowest and the highest values. Highest enzyme activities were found in the subfornical organ and in the posterior lobe of the pituitary gland. High ACE activity was also detected in the intermediate and anterior lobes of the pituitary gland, the caudate nucleus, and the medial habenular nucleus. Substantial activity also existed in the globus pallidus, the median eminence, the supraoptic and paraventricular nuclei, the lateral habenular nucleus and the organon vasculosum laminae terminalis. Our results demonstrate that one of the components of the renin-angiotensin system, the angiotensin-converting enzyme, is highly localized to a few discrete brain structures and the pituitary gland. These findings suggest that angiotensin II could be formed locally in some of these structures, supporting previous immunohistochemical data.

Animals↗
PubMed1998

Functional transplantation of the rat pituitary gland.

OBJECTIVE: These studies evaluated the ability of transplanted pituitary cells to restore pituitary function in hypophysectomized rats. METHODS: The pituitary glands of neonatal Lewis rats were rapidly removed, enzymatically dispersed, and stereotactically introduced into the third ventricle of hypophysectomized adult male Lewis rats. Four weeks after implantation, plasma levels of anterior pituitary hormones in implanted animals were compared with those of sham-transplanted control animals. RESULTS: Plasma levels of prolactin, growth hormone, thyroid-stimulating hormone, and beta-endorphin were below the range of detection in 14 sham-operated animals. In implanted animals, restitution of serum prolactin occurred in 100% of the animals tested, with levels of 2.6 +/- 1.0 ng/ml (mean +/- standard error of the mean; normal, 2-4 ng/ml). Growth hormone was assayable in 71% of the animals, with a mean value of 29 +/- 13 ng/ml over all animals (normal, 1-100 ng/ml); thyroid-stimulating hormone was restored in 68%, with mean resting levels of 79 +/- 13 ng/ml (normal, 100-400 ng/ml); luteinizing hormone levels were found in 53%, with mean levels over all animals of 0.2 +/- 0.1 ng/ml (normal, 0.5-1.0 ng/ml); and beta-endorphin was restored in 45% to high resting levels of 163 +/- 31 pg/ml (normal, 20-30 pg/ml). A challenge with hypothalamic releasing factor and a cold stress test were performed on the animals that had received transplants. Positive hormone responses to both of these tests suggested sensitivity of the pituitary grafts to both endogenous and exogenous sources of stimulation. Histological sections of paraformaldehyde-fixed brains from implanted animals clearly demonstrated survival of clusters of grafted pituitary cells. Positive immunohistochemical staining for adrenocorticotropic hormone and thyroid-stimulating hormone was demonstrated in sections of the grafted tissue. CONCLUSION: These data suggest survival of neonatal pituitary transplants in the third ventricle of adult hypophysectomized rats with concomitant restoration of anterior pituitary hormone function.

Animals↗
PubMed1986

The distribution of immunoreactive alpha-melanocyte-stimulating hormone cells in the adult human pituitary gland.

It has been suggested that a proportion of the adenomas and the nodular hyperplasia of cells in the pituitary gland in cases of Cushing's disease are derived from cells of the pars intermedia rather than the pars anterior. The evidence can be summarized as follows: the posterior site of adenoma or nodular hyperplasia in the pituitary, the innervation of cells and the suppressive response to the dopamine agonist bromocriptine in vivo or to dopamine in vitro. All these observations infer analogy with cells of the pars intermedia of other species, which are controlled by direct neural tonic dopaminergic inhibition. The adult human pituitary gland, however, does not possess a morphologically distinct pars intermedia, due to regression of the rudimentary fetal pars intermedia after birth, with mixing of cells into the pars anterior and pars nervosa. Since cells of the pars intermedia characteristically synthesize alpha-MSH, we have studied this peptide in order to assess the occurrence and distribution of intermedia-derived cells in the adult human pituitary. Sections from 100 pituitaries, removed at autopsy, were stained by an indirect immunoperoxidase technique using non-cross-reacting antisera specific for alpha-MSH and ACTH. Immunoreactive alpha-MSH (IR-alpha-MSH) cells were found in a total of 97 specimens. Of these, only ten cases showed a marked concentration of IR-alpha-MSH cells in the zona intermedia. In the majority of pituitaries, IR-alpha-MSH cells were more commonly seen in the pars anterior than in the zona intermedia; in 41 cases, IR-alpha-MSH cells were completely absent from the zona intermedia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1998

Magnetic resonance imaging evaluation of the pituitary gland and hypothalamus in thalassaemic children with elevated serum ferritin levels.

OBJECTIVE: Despite modern treatment with hypertransfusion and chelation therapy, growth retardation continues to be observed in a significant proportion of thalassaemic children. The underlying reason remains unclear, but hypothalamic-pituitary axis disorder has been implicated. We aimed to assess iron overloading in the hypothalamus and pituitary gland in thalassaemic children with elevated serum ferritin, with and without growth retardation. METHODOLOGY: Twelve thalassaemic children on hypertransfusion and chelation therapy with high serum ferritin were investigated with magnetic resonance imaging (MRI). Five children, all over 10 years of age, had growth retardation. Gradient recalled echo sequence was used to highlight any susceptibility effect that could be due to iron in the hypothalamus or pituitary gland. RESULT: There was no evidence of abnormal hypointense signal in the hypothalamus or pituitary gland in the patients studied, regardless of the presence of growth retardation. CONCLUSION: There was no apparent characteristic MRI appearances of iron deposition in the hypothalamus or pituitary gland in thalassaemic children with high serum ferritin.

Adolescent↗
PubMed1999

Regulation of growth hormone-releasing hormone receptor messenger ribonucleic acid expression by glucocorticoids in MtT-S cells and in the pituitary gland of fetal rats.

Regulation of GH-releasing hormone receptor (GHRH-R) messenger RNA (mRNA) expression was studied, with the ribonuclease protection assay, in the fetal rat pituitary gland and in MtT-S clonal cells. GHRH-R mRNA was first detected on embryonic day (E)19 and increased rapidly thereafter, to reach a maximum at E21. Incubation of E17 or E18 pituitaries with 50 nM dexamethasone (DEX), a synthetic glucocorticoid, induced GHRH-R mRNA expression, suggesting that glucocorticoids play a pivotal role in the developmental expression of this mRNA. In E19 pituitaries, 24 h treatment with DEX increased GHRH-R mRNA by 60%, and GH mRNA by 76%, but did not affect pit-1 mRNA level, suggesting that the effect of DEX is specific for expressions of GH mRNA and GHRH-R mRNA. The accumulation of GHRH-R mRNA by DEX was time dependent, and it was slightly enhanced by the protein synthesis inhibitor, puromycin (100 microM). In MtT-S cells (a pituitary cell line established from an estrogen-induced tumor), DEX induced GHRH-R mRNA expression within 2 h in a dose-dependent manner. This induction was augmented by puromycin (100 microM) or cycloheximide (3.5 microM). However, the RNA synthesis inhibitor Actinomycin D (1 microM) completely inhibited GHRH-R mRNA accumulation in response to either DEX or DEX plus puromycin, suggesting that glucocorticoids induce GHRH-R mRNA mainly through stimulation of mRNA transcription. These results suggest: that GHRH-R mRNA accumulation in the fetal pituitary gland of rats normally occurs at E19, probably because of the direct action of glucocorticoids on the pituitary gland, to stimulate GHRH-R mRNA transcription; and that the expression of glucocorticoid receptors is an important event in GH cell development in rats. Accordingly, immunocytochemical results suggest an increase in glucocorticoid receptors in immature GH cells between E17 and E18. The present results also imply that MtT-S cells may be a good model in which to further study the molecular mechanisms of the regulation of GHRH-R gene expression.

Animals↗
PubMed1996

The pituitary gland in nocturnal enuresis: MR findings.

Nocturnal enuresis is considered a benign condition partially explained by a defect circadian rhythm of vasopressin. An organic cause may be responsible for an abnormal pituitary function, when enuresis persists into adulthood. In the present study the pituitary gland and surroundings of 8 adults suffering from primary monosymptomatic nocturnal enuresis were studied by magnetic resonance imaging. The pituitary gland appeared normal in all, except from a Rathke's cleft cyst observed in one patient. This cleft cyst was not considered to be clinically important. It was concluded, that severe nocturnal enuresis persisting into adulthood is not likely to be combined with detectable pathology on magnetic resonance imaging of the pituitary gland.

Adult↗
PubMed1975

Identification of human luteinizing hormone, follicle-stimulating hormone, luteinizing hormone beta-subunit and gonadotrophin alpha-subunit in foetal and adult pituitary glands.

Specific radioimmunoassays were used to assess the content of LH, FSH, the gonadotrophin alpha-subunit and the LH beta-subunit in four adult, 19 normal foetal pituitary glands (9-5--32 weeks of gestation) and a pituitary extract from an anencephalic foetus (36 weeks). The hormones and subunits were further identified by column chromatography on Sephadex G-100. All pituitary glands contained free alpha-subunit and intact LH but the alpha-subunit:LH ratio was significantly higher in the early foetal pituitaries (9-5--16 weeks) than in the four adult pituitaries. Only small or undetectable amounts of LH beta-subunit and 'undetectable' FSH were found in these early foetal pituitaries (9-5--11-5 weeks). The concentration of intact hormones or subunits in the pituitaries showed no significant sex difference in any of the groups. In contrast to these results, only alpha-subunit was detectable in the pituitary of the anencephalic foetus. For 14 early foetuses (age of gestation 10--16 weeks) the serum levels of LH-HCG, FSH, and alpha-subunit in the circulation were significantly higher than in 26 foetuses at term (37--41 weeks). On the basis of these results a theory for the development of the gonadotrophin secretion from the foetal pituitary gland is outlined.

Adult↗
PubMed1989

The distribution of GAWK-like immunoreactivity in neuroendocrine cells of the human gut, pancreas, adrenal and pituitary glands and its co-localisation with chromogranin B.

GAWK is a recently discovered peptide isolated from extracts of human pituitary gland and subsequently shown to be identical to sequence 420-493 of human chromogranin B. The distribution of this peptide was studied in human gut, pancreas, adrenal and pituitary glands using antisera to two portions of the 74 amino acid peptide (sequences 1-17 and 20-38). In addition, the co-existence of GAWK immunoreactivity with other peptides and chromogranin B was investigated using comparative immunocytochemistry. In the gut, GAWK was localised mainly to serotonin-containing cells of the mucosal epithelium, where electron microscopy showed it to be stored in typical electron-dense (250 nm diameter) granules, and to a moderate population of nerve fibres in the gut wall. Considerable quantities of GAWK-like immunoreactivity were measured in the gut, up to 36.3 +/- 18 pmol GAWK 1-17/g wet weight of tissue (mean +/- SEM) and 12.4 +/- 2.9 pmol GAWK 20-38/g. Chromatography of gut extracts revealed several GAWK-like immunoreactive peaks. GAWK-like immunoreactivity was also detected in endocrine cells of pancreas, pituitary gland and adrenal medulla, where the highest concentrations of GAWK-like immunoreactivity were measured (GAWK 1-17 2071.8 +/- 873.2 and GAWK 20-38 1292.7 +/- 542.7 pmol/g). Endocrine cells containing GAWK-like immunoreactivity were found also to be immunoreactive for chromogranin B. Our results define a discrete distribution of GAWK immunoreactivity in human endocrine cells and nerves and provide morphological support for the postulated precursor-product relationship between chromogranin B and GAWK. Details of the functions of this peptide are awaited.

Adrenal Glands↗
PubMed1987

Angioarchitecture of the CNS, pituitary gland, and intracerebral grafts revealed with peroxidase cytochemistry.

Blood vessels of the fetal, neonatal, and adult subprimate and primate CNS, including circumventricular organs (e.g., median eminence, pituitary gland, etc.), and of solid CNS and nonneural (anterior pituitary gland) allografts placed within brains of adult mammalian hosts were visualized with peroxidase cytochemistry applied in three ways: to tissues from animals injected systemically with native horseradish peroxidase (HRP) or peroxidase conjugated to the lectin wheat germ agglutinin (WGA) prior to perfusion fixation; to tissues from animals infused with native HRP into the aorta subsequent to perfusion fixation; and to tissues from animals fixed by immersion and incubated for endogenous peroxidase activity in red cells retained within blood vessels. In neonatal and adult animals receiving native HRP intravascularly, non-fenestrated vessels contributing to a blood-brain barrier were outlined with HRP reaction product when tetramethylbenzidine (TMB) as opposed to diaminobenzidine (DAB) was used as the chromogen; fenestrated vessels of circumventricular organs were not discernible due to the density of extravascular reaction product. Fenestrated and non-fenestrated cerebral and extracerebral blood vessels exposed to bloodborne WGA-HRP were visible when incubated in TMB and DAB solutions. Native HRP infused into the aorta of fixed animals likewise labeled non- fenestrated vessels throughout the brain upon exposure to TMB or DAB but obscured fenestrated vessels of the circumventricular organs. Endogenous peroxidase activity of red cells, seen equally well with TMB and DAB, outlined blood vessels throughout the cerebral gray and white matter and all circumventricular organs in fetal, neonatal, and adult animals. Application of the three peroxidase cytochemical approaches to study the development or absence of a blood-brain barrier in intracerebral allografts demonstrated that the vascularization of day 16-19 fetal/1 day neonatal CNS allografts is not well defined prior to 7 days following intracerebral placement of the grafts. CNS allografts secured from donor sites expected to possess a blood-brain barrier exhibited blood vessels that were not leaky to HRP injected intravenously in the host. Fenestrated blood vessels associated with anterior pituitary allografts were evident prior to 3 days posttransplantation within the host brain and permitted blood-borne HRP in the host to enter the graft and surrounding host brain parenchyma.

Animals↗
PubMed1992

Effects of angiotensin II on LHRH release, as measured by in vivo microdialysis of the anterior pituitary gland of conscious female rats.

The present experiments assessed the effects of central administration of angiotensin II (Ang II) on mean levels of luteinizing hormone-releasing hormone (LHRH) in the extracellular fluid of the anterior pituitary gland, monitored by in vivo microdialysis. Ovariectomized rats were tested under two conditions: (1) nonhormone-treated where Ang II infusion inhibits luteinizing hormone (LH) release, and (2) ovarian hormone-treated where Ang II stimulates LH secretion. Animals were ovariectomized and chronic guide cannulae were implanted, one into the lateral cerebral ventricle for infusion of Ang II and one directed toward the anterior pituitary gland for the insertion of the microdialysis probe. Approximately 1 week later, the dialysis probe was inserted and cemented into place. The length of the dialysis probe transected the pituitary gland from its dorsal to ventral aspects. Dialysis samples were collected at 15-min intervals. Levels of LHRH were continuously monitored in nonhormone-treated animals, prior to and during intracerebroventricular (i.c.v.) infusion of Ang II. The dialysis probe was removed at the end of the experiment. One week later, the same animals were treated with estrogen and progesterone and dialysis of the anterior pituitary gland was performed 3 days later using a protocol identical to the first dialysis sampling session. A separate group of animals was tested to confirm the effects of lateral ventricle infusion of this dose of Ang II on LH release. There were no detectable values of LHRH in dialysis samples from non-hormone-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed2005

Cellular localization of IL-18 and IL-18 receptor in pig anterior pituitary gland.

Pro-inflammatory cytokine interleukin 18 (IL-18) has been proposed to have a role in modulating immuno-endocrine functions. Our previous study showed that IL-18 and IL-18 receptor (IL-18R) colocalized in somatotrophs of the bovine anterior pituitary gland, and the possibility that IL-18 acts on somatotrophs as an autocrine factor. In the present study, we investigated the localization of IL-18 and IL-18R in the pig anterior pituitary gland. RT-PCR analysis showed the expression of IL-18 and IL-18R mRNAin the pig anterior pituitary gland. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs, mammotrophs, thyrotrophs and gonadotrophs. IL-18R was localized in somatotrophs and thyrotrophs. Furthermore, the somatotrophs immunoreactive for IL-18 did not contain IL-18R. Thus, IL-18R and IL-18 were not colocalized in an identical somatotroph. These findings suggest that the localization of IL-18 in pig somatotrophs is different from that in bovine somatotrophs, although IL-18 closely associates with somatotrophs in the anterior pituitary glands in both species.

Animals↗
PubMed1985

Light and electron microscopic localization of the N-terminal fragment of human pro-opiomelanocortin in the human pituitary gland and in neoplasms.

Immunohistochemical localization of the N-terminal fragment (1-76) (NTF) of human pro-opiomelanocortin (POMC) was studied in human adult and fetal pituitary glands, as well as in pituitary adenomas associated with Cushing's syndrome and in ectopic ACTH-producing tumors. Comparison of localization between NTF and ACTH was performed using mirror sections. Our results indicated concomitant localization of NTF and ACTH in the same cells, not only in normal adult and fetal pituitaries but also in pituitary adenomas and ectopic ACTH producing tumours. Specificity of the NTF staining was confirmed by immunoabsorption. Negative staining of the bovine pituitary gland indicated the immunohistochemical localization of N-terminal (1-45) of human POMC as there is a known species difference in the sequence 1-45 between human and the bovine N-terminal fragment. Presence of NTF in cisterna of rough endoplasmic reticulum indicates its production by small cell carcinoma. These findings, together with the previous studies, suggest that the complete form of POMC is produced in the tumours as well as in normal pituitaries.

Adenoma↗
PubMed2001

Papillary carcinoma of thyroid metastatic to the pituitary gland.

We describe a 35-year-old woman who presented with diabetes insipidus caused by metastatic papillary carcinoma of the thyroid involving the pituitary gland, 25 years after treatment for a papillary carcinoma of thyroid and 17 years after treatment for multiple pulmonary metastases. The literature contains 10 previously described cases of metastatic thyroid carcinoma involving the sella, but only 2 of these cases had unequivocal metastases to the pituitary gland, making the present case, to our knowledge, the third reported case of unequivocal hematogenous metastasis of thyroid carcinoma to the pituitary gland. The pituitary tumor was removed by transsphenoidal surgery, and the tissue was examined by conventional histology, extensive immunohistochemistry, and electron microscopy. The findings confirmed the tumor to be papillary thyroid carcinoma. To our knowledge, this is the first report citing use of thyroid transcription factor-1 to establish a thyroid source of a pituitary metastasis.

Adult↗