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PubMed1990

Determination of guanine nucleotide sensitivity of [125-I]-neuropeptide Y binding in the rat pituitary gland by quantitative autoradiography.

[125I]-neuropeptide Y receptors were characterized in the rat pituitary gland using quantitative autoradiography. Scatchard analysis of saturation isotherms showed high affinity (Kd 8.5 x 10(-11) M) and single class of binding sites (Bmax 0.22 pmol/mg of protein) in the posterior lobe of the pituitary gland, with no specific binding in the intermediate or anterior lobe. Increasing concentrations of guanine nucleotide analogues and peptide YY inhibited neuropeptide Y binding. In addition, neuropeptide Y binding was pertussis-toxin-sensitive. These results add additional information about a possible neuronal (through neuropeptide Y) and hormonal (through peptide YY) regulation of posterior pituitary function, which is most probably GTP-dependent.

Animals↗
PubMed1979

Some biochemical characteristics of hormone-secreting pituitary tumors and of the host's anterior pituitary gland.

The activity of some glycolytic, oxidative, and degradative enzymes was studied in transplanted rat hormone-secreting pituitary tumors MtTW15 and 7315a and in the host pituitary gland. The elevated serum-hormone concentrations produced by 7315a tumor decreased the size of the host's pituitary gland, its hormone content, and G6P-DH, LDH, PK, and ICDH, but produced no changes in MDH, acid phosphatase, cathepsin-D, and LYSAR enzyme activities (mU/mg tissue). LDH and PK activities were greater in unit weight of pituitary tumors than in pituitary glands. Although more G6P-DH was found in MtTW15 tumor than in normal pituitary tissue, less of the enzyme was detected in 7315a pituitary tumor. It is concluded that elevated serum pituitary hormones selectively decrease hormone production and the activity of some enzymes in the pituitary gland, presumably through a feedback mechanism.

Animals↗
PubMed1995

[Effects of lesion or stimulation of pituitary gland and hypothalamic arcuate nucleus on pain modulation in rats].

Relationship between pituitary gland and hypothalamic arcuate nucleus (ARC) in the modulation of pain threshold was investigated in Wistar rats with method of focal lesion and stimulation of pituitary gland. Experimental results indicated that electrolytic lesion of the pituitary intermediate and anterior lobes resulted in a decrease of pain threshold and disappearance of the analgesia immediately produced by ARC stimulation. Stimulation of the same area of pituitary gland could induce a delayed analgesia, which could be blocked by ARC lesion.

Animals↗
PubMed1997

Cell-specific induction of c-fos expression in the pituitary gland by estrogen.

Estrogens regulate many functions of pituitary lactotrophs, including PRL gene expression, release, storage, and cellular proliferation. The mechanism by which estrogens exert such a variety of functions is poorly understood. In the uterus, estrogens rapidly and transiently induce the expression of the immediate early genes c-fos and c-jun in specific cell types. The Fos/Jun proteins form the activating protein-1 (AP1) transcription factor that mediates ligand-activated cell proliferation, differentiation, and secretion. Here we used Fischer 344 (F344) rats that develop hyperprolactinemia and prolactinomas in response to estrogens. The objectives were to: 1) determine whether estrogen induces c-fos expression in the pituitary gland and identify the responsive cells; 2) compare the dynamics of c-fos induction in the pituitary and uterus; and 3) examine the temporal relationship between c-fos expression and PRL release. Ovariectomized F344 rats were injected with 1 microg estradiol and killed at different times thereafter. Pituitaries were subjected to in situ hybridization for c-fos and immunostaining for selected pituitary cells. Estradiol stimulated c-fos expression in lactotrophs and folliculo-stellate cells within the anterior lobe without affecting either the intermediate or neural lobes. In a second experiment, c-fos messenger RNA levels were measured by solution hybridization in anterior pituitaries and uteri from estradiol-treated rats. Trunk blood was analyzed for PRL by RIA. The estrogen-induced c-fos rise in the uterus was rapid, robust, and transient, whereas that in the anterior pituitary was delayed, lower, and sustained. The profile of serum PRL levels resembles that of c-fos induction in the anterior pituitary. We conclude that: 1) both lactotrophs and folliculo-stellate cells increase c-fos expression in response to estrogens; 2) induction of c-fos expression may mediate some estrogenic effects on PRL synthesis and release and lactotroph proliferation in F344 rats; and 3) the atypical dynamics of c-fos induction in the pituitary could be due to indirect effects of estrogens on PRL-regulating factors within the hypothalamo-pituitary complex as well as to pituitary-specific estrogen receptor isoforms, coactivators, or repressors.

Animals↗
PubMed1985

Further studies on the localization of angiotensin-II-like immunoreactivity in the anterior pituitary gland of the male rat, comparing various antisera to pituitary hormones and their specificity.

Using immunocytochemistry with the sensitive avidin-biotin complex method and an antibody to the beta subunit of rat luteinizing hormone (rat LH beta) provided by the National Hormone and Pituitary Program, NIADDK, to identify gonadotrops, the presence of angiotensin II-like immunoreactivity in the gonadotrops of the anterior pituitary gland of male rats was confirmed. However, using an antibody to rat prolactin, no angiotensin II-like immunoreactivity could be found in lactotrops. This finding is at variance with a previous report from this laboratory, in which the lactotrops were identified with an NIADDK antibody to human prolactin. The possibility that the antibodies to human prolactin cross-reacted with rat LH was therefore investigated by a noncompetitive radioimmunological binding assay. At the same dilution used in immunocytochemistry, two different NIADDK antihuman prolactin antisera displayed 49% and 24% binding of labeled rat LH beta. Similar cross reactions were demonstrated immunocytochemically. There was no cross reactivity between rat LH beta and the antibody to rat prolactin. Consequently, the staining reported to be in lactotrops in the previous study was probably in gonadotrops.

Angiotensin II↗
PubMed1987

Ectopic pituitary gland simulating a suprasellar tumor.

A case report of ectopic pituitary gland in the suprasellar region of a normal 39-year-old woman with persistent headaches is presented. The embryological development of the pituitary gland is briefly reviewed, with a discussion of the relevant literature. No previous report of normal pituitary tissue in a suprasellar location in the absence of tumor could be found.

Adult↗
PubMed1998

Effects of a low-protein diet on prolactin- and growth hormone-producing cells in the rat pituitary gland.

BACKGROUND: It is well known that an unbalanced diet induces various changes in the pituitary gland. However, little attention has been paid to the molecular aspects of this perturbation. We studied the influence of a low-protein diet (LPD) on the prolactin (PRL) and growth hormone (GH) cells in the rat pituitary gland using immunohistochemical staining and in situ hybridization. MATERIALS: Rats aged 20 days were fed a diet containing 27% protein or one with 8% protein (LPD) for 30 days. Pituitary glands were obtained and subjected to either immunohistochemistry or in situ hybridization. Quantitative morphological analysis was then conducted to determine cell number and area as well as the percentage of cells stained by the respective antisera and/or cDNA probe in each experimental group. RESULTS: The average sectional areas of both PRL- and GH-producing cells in the LPD group were smaller in size than those in the controls. The cell numbers per unit area (mm2) of PRL-positive cells and PRL mRNA-positive cells were 3,596.5 and 3,948.6, respectively, in the LPD group, and 3,179.6 and 4,888.5, respectively, in the controls. The numbers per unit area of GH-positive cells and GH mRNA-positive cells in the LPD group were similar (2,252.3 and 2,224.4), as compared to 2,161.3 and 1,684.2, respectively, in the well-fed rats. Whereas PRL-positive cells comprised about 27% of the total number of cells in both animal groups, those given the LPD contained a lower percentage (29%) of PRL mRNA-positive cells as compared to the controls (44%). On the other hand, GH mRNA-positive cells numbered about 15% of the total cell population both animal groups; however, the malnourished rats contained a lower percentage (16%) of GH-positive cells than did their well-fed counterparts (20%). CONCLUSIONS: Taken together, these results indicate that in the rat pituitary gland, administration of an LPD reduced the size of PRL- and GH-positive cells as well as differentially affecting a subpopulation of the PRL mRNA-positive cells and the GH-positive cells.

Animals↗
PubMed2006

Expression of retinaldehyde dehydrogenase (RALDH)2 and RALDH3 but not RALDH1 in the developing anterior pituitary glands of rats.

Retinoic acid (RA) plays an important role in cell growth and tissue development and is also a regulating factor of pituitary function. However, whether RA is generated in the pituitary gland and plays a role as a paracrine and/or autocrine hormone is generally unknown. RA is synthesized from retinoids through oxidation processes. Dehydrogenases catalyzing the oxidation of retinal to RA are members of the retinaldehyde dehydrogenase (RALDH) family. In this study, we examined the expression of RALDH1, RALDH2, and RALDH3 mRNA in the rat embryonic pituitary gland. By in situ hybridization with digoxigenin-labeled cRNA probes, we detected mRNA expression for RALDH2 and RALDH3, but not RALDH1. The expression of RALDH2 and RALDH3 was located in Rathke's pouch at embryonic day 12.5 (E12.5) and subsequently in the developing anterior pituitary gland. We also used quantitative real-time polymerase chain reaction to analyze RALDH2 and RALDH3 mRNA expression levels during the development of the pituitary gland. We found that pituitary RALDH2 and RALDH3 mRNA levels were high at E17.5 and decreased markedly after birth. Our study is the first to show that RALDH2 and RALDH3, but not RALDH1, are expressed in the embryonic anterior pituitary gland of the rat.

Aldehyde Dehydrogenase 1 Family↗
PubMed1976

Ultrastructure of the "non-pathologic" human pituitary gland.

The ultrastructure of "non-pathologic" human pituitary gland obtained from eight cases at autopsy, who received no hormonal therapy and who revealed no significant changes in the pituitary and its target organs, was investigated in an attempt to identify human adenohypophyseal cells by comparing their secretory granules with those of experimental animals. Besides the follicular cell, five different granulated cell types were distinguished The Type 1 cell contained abundant, dense secretory granules (350-500 mmu across). The Type II cell was characterized by dense granules, which were the largest in size (500-700 mmu across) and the most irregular in shape. Granules of the Type III cell were less characteristic (200-300 mmu across). The Type IV cell contained dense granules, which were the smallest in size (100-150 mmu across) and were characteristically arranged along the plasma membrane. The Type V cell was characterized by the presence of small, haloed granules (100-200 mmu across). The cells of these five types could presumably be the somatotroph, lactotroph, gonadotroph, thyrotroph and corcitotroph, respectively.

Adult↗
PubMed1995

Hemodialysis: relationship between signal intensity of the posterior pituitary gland at MR imaging and level of plasma antidiuretic hormone.

PURPOSE: To investigate the correlation between signal intensity of the posterior pituitary gland on magnetic resonance (MR) images and levels of plasma antidiuretic hormone (ADH) in patients undergoing hemodialysis. MATERIALS AND METHODS: The cases of 25 patients undergoing hemodialysis (15 men and 10 women, aged 24-75 years [mean, 51 years]) were prospectively evaluated. Laboratory testing and MR imaging were performed both before and after hemodialysis in 14 patients and only before hemodialysis in 11 patients. RESULTS: Before hemodialysis, nine patients (36%) had normal hyperintensity in the posterior pituitary gland, with almost normal plasma ADH levels and slightly elevated plasma osmolality. In six patients (24%) with less hyperintensity than is characteristic in the posterior pituitary gland, plasma ADH levels were slightly increased or normal. In 10 patients (40%) with an isointense posterior pituitary gland, plasma ADH and osmolality levels were evaluated. CONCLUSION: Elevated plasma osmolality may cause increased plasma ADH concentration and a lack of hyperintensity in the posterior pituitary gland at MR imaging.

Adult↗
PubMed2004

Development of thyroid-stimulating hormone beta subunit-producing cells in the chicken embryonic pituitary gland.

In previous studies, the distribution of thyrotropes in the chicken pituitary gland has been analyzed by immunohistochemistry using heterologous antibodies. In this study, we examined the distribution of thyroid-stimulating hormone beta subunit-immunopositive (TSHbeta-ip) cells and the expression of TSHbeta mRNA in the pituitary glands of chicken embryos by immunohistochemistry using a specific antiserum to the chicken TSHbeta, in situ hybridization and RT-PCR. Immunohistochemical and morphometric analyses revealed that the TSHbeta-ip cells first appeared on embryonic day 10 (E10) in the pituitary gland and were mainly distributed in the cephalic lobe and that the cell density on E20 was almost 4 times greater than that on E10. The chicken TSHbeta-ip cells could be classified into two types based on morphological characteristics: round-shaped cells and club-shaped cells, which have long cytoplasmic processes. In situ hybridization analysis revealed that TSHbeta mRNA-expressing cells were expressed from E9 in the cephalic lobe and that the extent of TSHbeta mRNA-expressing cells coincided with that of TSHbeta-ip cells. RT-PCR also showed that TSHbeta mRNA was expressed from E9 and that Pit-1 mRNA was expressed from E5. These results clearly demonstrated that the expression of chicken TSHbeta mRNA starts on E9, that TSHbeta-ip cells appear on E10, mainly in the cephalic lobe, and that TSHbeta-ip cells can be classified into two cell types (round- and club-shaped cells).

Animals↗
PubMedDate not supplied

Tumor necrosis factor-alpha: specific binding sites in rodent brain and pituitary gland.

Specific binding sites for TNF-alpha in mouse and rat brain, spleen and pituitary gland have been visualized and characterized, using quantitative autoradiography. Mouse recombinant 125I-TNF-alpha has been used as a radioligand. In the spleen, TNF-alpha binding sites were highly concentrated in the white pulpe of mouse and rat spleen. The IG50, as determined by displacement of radioligand by the unlabelled peptide, was 0.3 x 10(-9) M for both species. In the mouse brain, a weak specific binding was observed on the entire surface of the brain tissue. However, none of the nervous or vascular structures were specifically labelled above this signal. No specific binding was detectable in the rat brain tissue. In sharp contrast, in the anterior lobe of the pituitary gland of both mouse and rat, high concentrations of specific binding sites were detectable. Displacement curves in the mouse pituitary gland revealed the presence of two classes of binding sites with respective IC50 values of 10(-9) and 5 x 10(-11) M. A single class of TNF binding site was demonstrated in the rat with an IC50 of 10(-9) M. The presence of TNF binding sites in the anterior pituitary gland underlines the existence of regulatory pathways between the immune and neuroendocrine system.

Animals↗
PubMed1984

In-vitro effects of corticosterone, synthetic ovine corticotrophin releasing factor and arginine vasopressin on the release of adrenocorticotrophin by fetal rat pituitary glands.

The in-vitro release of ACTH by fetal rat pituitary glands on days 17, 19 and 21 of pregnancy was measured using radioimmunoassay. The spontaneous release of ACTH, expressed in pg ACTH/gland per h, increased with fetal age, in correlation with the sharp rise in pituitary ACTH content. However, since pituitary ACTH content was nearly sevenfold higher at term than on day 17, while basal release of ACTH was only threefold higher, one can speculate that the spontaneous release of ACTH was proportionally greater on day 17 than on day 21 of gestation. As corticosterone, at a physiological concentration (865 nmol/l), reduced ACTH release, it was concluded that the pituitary gland was one site of the negative feedback action of the corticosteroids during fetal life. Quantities of synthetic ovine corticotrophin releasing factor (CRF) which gave concentrations of 0.3-30 nmol/l in the incubation medium induced a sharp rise in ACTH release which was log-dose dependent between 0.3 and 3 nmolCRF /1 on day 17 and between 0.3 and 30 nmolCRF /1 on days 19 and 21. The response to CRF increased with fetal age. Quantities of arginine vasopressin (AVP) which gave concentrations of 2-200 nmol/l stimulated ACTH release at all stages of gestation investigated. However, the response to AVP was much lower than that to CRF. Potentiation of CRF-induced ACTH release was not observed when whole pituitary glands from 21-day-old fetuses were incubated with AVP (20 nmol/1) + CRF ( 3nmol /1). Such results were correlated with the ontogenesis of immunoreactive vasopressin- and CRF-containing fibres in the median eminence of the rat fetus, as well as with the CRF-like immunoreactivity present in adult rat pituitary portal plasma and the AVP content of the fetal rat hypophysis.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

The bright pituitary gland--a normal MR appearance in infancy.

Signal intensities of the pituitary gland were measured on T1-weighted sagittal MR images of 25 patients younger than 20 years old. We found that the signal intensities in the eight patients who were 8 weeks old or younger were higher (shorter T1) than those in the 17 older patients. We also noted a difference in the signal intensities across the pituitary gland, the signal being higher in the posterior part of the gland than in the anterior part. We attribute the high signal intensities to the rapid intrauterine pituitary growth, so that at term pituitary protein synthetic activity is at a maximum. Possibly, an increase in the bound fraction of the water molecules of the gland may also be present in the neonatal pituitary as compared with the older gland, but this remains to be proved. The higher signal in the posterior pituitary gland may be due to lipid in the pituicyte cells of the posterior pituitary gland.

Adolescent↗
PubMed2002

Abrupt pubertal elevation of DNase I gene expression in human pituitary glands of both sexes.

Deoxyribonuclease I (DNase I) was confirmed to be expressed in the human pituitary gland, particularly the anterior lobe, at levels comparable to those in the pancreas. The DNase I activity and the amount of gene transcript present in the pituitary glands of individuals aged from 1 month to 89 years was significantly age-dependent, with an abrupt elevation after the neonatal and prepubertal periods irrespective of gender, followed by a gradual age-dependent decline in males and a marked reduction in females in their postreproductive period. This DNase I age dependence in the pituitary gland was not present in the pancreas and serum. These observations suggest that tissue-specific up-regulation of DNase I gene expression in the pituitary gland occur, possibly at the onset of puberty.

Adolescent↗
PubMed1977

Staining of human pituitary glands with lead hematoxylin in comparison with other histochemical procedures, including the immunoenzyme technique.

Human pituitary glands and pituitary adenomas, obtained by surgery or at autopsy, have been stained with lead hematoxylin and the results were compared with those of other histochemical procedures, including the immunoperoxidase technique. Lead hematoxylin positivity was found in the cytoplasm of melanocorticotroph, thyrotroph as well as gonadotroph cells, indicating that lead hematoxylin has no selective affinity for melanocorticotroph cells. Lead hematoxylin positive cells also stained with the PAS technique. Lead hematoxylin positivity was not revealed in growth hormone cells or in prolactin cells. Basophilic adenomas, composed of melanocorticotroph cells and associated with Cushing's disease or with Nelson's syndrome or unaccompanied by hormonal hypersecretion, showed intense lead hematoxylin positivity. Thus, no correlation was evident between lead hematoxylin positivity and secretory activity. Acidophilic or chromophobic adenomas consisting of growth hormone cells, prolactin cells, stem cells, undifferentiated cells or oncocytes, however, were negative. It can be concluded that the lead hematoxylin staining techniques a reliable, easy and reproducible histochemical method, and its use can be recommended in studies related to adenohypophysial cytology.

Adenoma↗
PubMed1987

Immunolocalisation of cytokeratins in the normal and neoplastic human pituitary gland.

Cytokeratins were studied by immunocytochemical techniques at light and electron microscopy on 12 normal pituitary glands, 30 pituitary adenomas and three craniopharyngiomas. The results are presented in relation to clinical and biochemical features and new information on the subcellular localisation of cytokeratins in pituitary cells is discussed.

Adenoma↗