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At least 685 records · Page 38Linked to original sources
PubMed1994

The expression of the calcitonin receptor gene in the brain and pituitary gland of the rat.

The distribution of rat calcitonin receptor mRNA in the brain and pituitary gland were examined by in situ hybridization. Labelled cells were found in the nucleus accumbens, the preoptic and medial preoptic areas, the paraventricular nucleus of the hypothalamus, and the arcuate nucleus; a smaller number of cells were found in the brainstem and olfactory bulb. No strongly labelled cells were found in the pituitary gland.

Animals↗
PubMed1992

[Isolation of prolactin from lyophilized porcine pituitary glands].

The optimal conditions for lyophilization of porcine pituitary glands and isolation of pure prolactin from lyophilized preparation have been investigated. The isolation method consisted in the extraction of crude pituitary preparation with acidified acetone followed by precipitation of crude prolactin preparation (acid acetone powder) by increasing the concentration of acetone in the extract to 92%. Further purification of prolactin was achieved by fractional precipitation at varying pH values and gel filtration on Sephadex G-75 column in a pH 7.5 phosphate buffer. This final procedure resulted in obtaining the monomeric form of prolactin. The identity of the isolated hormone was confirmed by spectrophotometric and radioimmunological methods as well as by polyacrylamide gel electrophoresis.

Animals↗
PubMed1982

Effect of haloperidol on the synthesis of DNA in the pituitary gland of the rat.

The administration of haloperidol increased serum prolactin and decreased the pituitary concentration of prolactin 15 min after its administration. Concomitantly there was a stimulation in the synthesis of DNA and the activity of DNA polymerase alpha in the anterior pituitary gland that was greater in oestrogenized than in non-oestrogenized male rats. Both these effects were greatly reduced by clomiphene in the oestrogenized male rats, although it did not affect the release of prolactin produced by haloperidol. In non-oestrogenized animals clomiphene abolished the stimulatory effect of haloperidol on the synthesis of DNA. These results suggest that the reduction in the intracellular levels of prolactin are a primary event in the oestrogen mediated stimulation of cell proliferation by prolactin releasing agents.

Animals↗
PubMed1992

Immunohistochemical localization of keratin in bull, goat, and sheep anterior pituitary glands.

Immunohistochemical localization of keratin, an intermediate filament protein, was studied in bull, goat, and sheep anterior pituitary glands, i.e., in animals of the order Artiodactyla. Strong immunoreactivity was detected in the cells of the marginal layer of bull and goat, as well as in cysts or large follicles in the anterior lobe of all 3 species. In addition, a number of stellate-shape cells were immunoreactive for keratin and were distributed throughout the anterior lobe. The localization of keratin-positive cells in light-microscopic preparations correlated precisely with the localization of folliculo-stellate cells in adjacent ultrathin sections. In ultrastructural studies, many slender and elliptical membranous components which were different from smooth endoplasmic reticulum were observed in the cytoplasm of the some keratin-positive cells. Some of the folliculo-stellate cells in the 3 species were also immunoreactive for the alpha subunit of S-100 protein, which exists in some epithelial cells. On the other hand, immunolocalization of glial fibrillary acidic protein, a glial cell marker, could not be demonstrated in the anterior pituitary glands of the 3 species studied. These results suggest that keratin-positive folliculo-stellate cells express epithelial-like characteristics.

Animals↗
PubMed1987

Effects of alcohol feeding on androgen receptors in the rat pituitary gland.

Specific binding of testosterone-1 beta, 2 beta-3H by cytosol from anterior pituitary gland of alcohol-fed, isocaloric control, and castrated control and alcohol-fed rats with or without testosterone treatment has been investigated by charcoal assay. The number of androgen binding sites was significantly reduced in alcohol-fed rats (8 +/- 1.0 fmoles/mg cytosol protein), when compared to the isocaloric control value (13.2 +/- 2.1 fmoles/mg protein), with no significant change in Kd (0.7 +/- 0.14 nM). Castration significantly increased the number of receptor sites in control rats and when castrated control animals were treated with testosterone the binding sites were decreased to the intact control level. In contrast, castration or testosterone given to castrated alcohol-fed rats did not alter alcohol-induced reduction of the receptor sites. The binding affinity (Kd) is identical in all groups. The concentration of serum luteinizing hormone (LH) was significantly lower in alcohol-fed rats when compared to that of normal controls. An increased serum LH level with a decreased testosterone level was noted in castrated control rats. However, castration of alcohol-fed rats had little or no effects on the concentrations of LH and testosterone. Administration of testosterone suppressed castration-induced high LH in control rats but alcohol-induced reduction of LH level was not altered by this treatment. These findings indicate that alcohol exerts a suppressive effect on the content of androgen receptors and secretory functions of gonadotropins in the pituitary gland.

Animals↗
PubMed1992

The presence, characterisation and synthesis of neuromedin B in the human pituitary gland.

Neuromedin B is a 10-amino-acid mammalian peptide of the bombesin family. We have used a specific radioimmunoassay and Northern blot hybridisation to investigate the possible synthesis of neuromedin-B-like immunoreactivity in the human pituitary gland. The concentration of immunoreactive neuromedin B in whole human pituitary was 15.2 +/- 4.2 pmol/g wet weight in males and 12.8 +/- 2.7 pmol/g wet weight in females (mean +/- SEM, n = 10). In pituitary tumour extracts, neuromedin B immunoreactivity was 9.1 +/- 1.7 pmol/g wet weight (mean +/- SEM, n = 14) in inactive tumours, 18.4 +/- 6.9 pmol/g wet weight (mean +/- SEM, n = 4) in somatotrophs and 10.4 +/- 2.7 pmol/g wet weight (mean +/- SEM, n = 2) in prolactinomas, with no apparent significant difference between the groups. Gel permeation chromatography of pituitary extracts revealed two immunoreactive peaks, the major one of which corresponded in position to that of neuromedin B-32 and a later minor peak to the position of the neuromedin B-10 standard. On fast protein liquid chromatography, neuromedin-B-like immunoreactivity again eluted in two peaks, a minor peak corresponding to the synthetic neuromedin B standard, and a major more hydrophobic peak which was the big neuromedin B form. Northern blot analysis of poly(A)+RNA from human pituitaries revealed the presence of a hybridising band of between 750 and 850 base pairs. These results suggest that neuromedin B is synthesised in the human pituitary gland where it may be of importance in the regulation of pituitary function. Furthermore, the adenomatous condition is not associated with abnormal levels of this peptide.

Aged↗
PubMed1993

Effects of the opioid antagonist naltrexone-estrone azine on the luteinizing hormone-releasing hormone induced release of luteinizing hormone from the pituitary glands of ovariectomized rats.

The effects were studied of in vivo administration of the new opioid antagonist-estrogen hybrid, naltrexone-estrone azine (EH-NX), on subsequent luteinizing hormone-releasing hormone (LHRH)-stimulated luteinizing hormone (LH) release by the pituitary gland in vitro. It is well known that administration of estrogen exerts negative and positive effects on the pituitary LH response to LHRH, respectively after short-term and long-term treatment. Rats were injected subcutaneously with either 17 beta-estradiol-3-benzoate (EB), EH-NX or oil on days 18 and 19 (long-term treatment), and on day 21 (short-term treatment) following ovariectomy. Twenty minutes later the animals were killed and the pituitary glands were incubated in the presence of LHRH (1000 ng/ml) for 4 h. Whereas short-term treatment with EB on day 21 did not affect LH release in vitro, EH-NX significantly decreased the pituitary LH response to LHRH in oil pretreated rats. This inhibitory effect was partially blocked by the opioid antagonist naltrexone. After long-term EB or EH-NX, followed by short-term oil treatment, the pituitary LH response to LHRH was increased considerably, compared to the long-term oil controls. These observations demonstrate that the opioid antagonist estrogen hybrid EH-NX has estrogenic activity at the level of the pituitary gland. This hybridized drug is more effective in time than EB and an equimolar amount of EH (estrone hydrazone) to induce the negative estrogenic effect.

Animals↗
PubMed1995

Identification and localization of gene expression of a low M(r) GTP-binding protein, ram p25 in pituitary gland.

The localization of gene expression of a low M(r) GTP-binding protein, ram p25, was examined throughout the entire brain of adult rat by in situ hybridization. ram-mRNA was expressed predominantly in anterior and intermediate lobes of pituitary gland (hypophysis), and weakly in hippocampal formation. In other parts of brain, no significant expression of ram-mRNA was detected, indicating that ram p25 may have an important role(s) in adenohypophysis. In 15-day-fetal rat, the mRNA was observed to be expressed strongly in the primitive anterior lobe of pituitary gland. The ram p25 was also detected in bovine pituitary gland by a specific antibody and was purified to near homogeneity by stepwise column chromatographies. Biochemical characterization of the purified ram p25 revealed that the profile of [35S]GTP gamma S-binding activity was almost the same as that of recombinant ram p25 expressed in E. coli.

Amino Acid Sequence↗
PubMed1991

Endothelin in human brain and pituitary gland: comparison with rat.

To investigate the physiological roles of endothelin (ET) in the brain and pituitary gland, the presence of immunoreactive (ir) ET and ET receptors was studied by radioimmunoassay and receptor assay in humans and rats. ir-ET concentrations in human brain (6-10 fmol/g of wet weight) were comparable with the levels in the rat brain (5-9 fmol/g of wet weight). Higher concentrations of ir-ET were found in human pituitary glands (147 +/- 30 fmol/g of wet weight, mean +/- SEM) and rat posterior pituitary lobes (88 +/- 26 fmol/g of wet weight). Fast protein liquid chromatography (FPLC) showed that the ir-ET in human hypothalamus and brainstem was mainly ET-1, while the ir-ET in human pituitary was mainly ET-3. FPLC of the whole rat brain extract showed a larger peak in the position of ET-3 and a smaller peak in the position of ET-1. Receptor assay showed that [125I]ET-1 binding sites were present in very large numbers in all five human brain regions and four rat brain regions examined but were much less abundant in the human pituitary. ET mRNA was detected by Northern blot hybridization in human pituitary but not in human hypothalamus. These findings are in accord with the possibility that ET acts as a neurotransmitter, neuromodulator, or neurohormone.

Animals↗
PubMed1983

Prostaglandin D2 stimulates secretion of luteinizing hormone from pituitary gland in vitro.

The effect of prostaglandin D2 on the release of luteinizing hormone was studied in a superfusion system by superfusing human pituitary gland. Perfusion with 30 micrograms of prostaglandin D2 induced a significant increase of luteinizing hormone secretion. This is the first evidence of a direct effect of prostaglandin D2 on the secretion of luteinizing hormone from the human pituitary gland. This finding suggests the possible role of prostaglandin D2 in human reproductive function.

Adult↗
PubMed1998

Relationship between prolactin receptor mRNA in the anterior pituitary gland and hypothalamus and reproductive state in male and female bantams (Gallus domesticus).

The aim of this study was to test the hypothesis that prolactin may up- and down-regulate prolactin receptor gene expression in the anterior pituitary gland and hypothalamus respectively. Experiments were carried out in bantams (Gallus domesticus). Comparisons were made of concentrations of PRLR mRNA in the anterior pituitary gland and basal and preoptic hypothalamus in adult males and females held on long days (low vs high plasma prolactin); in 3-week-old juvenile male and females on short days (high vs low plasma prolactin); in 8-week-old juvenile male and females on short days (both low plasma prolactin); in adult laying, incubating, and out-of-lay (high, very high, and low plasma prolactin, respectively); in adult cockerels exposed to long or short days (high vs low prolactin); and in adult hens exposed to long or short days (high vs low prolactin). There was a sex difference in anterior pituitary and basal hypothalamic PRLR mRNA, with lower values in both tissues in females than in males. Compared with laying and out-of-lay hens, anterior pituitary and basal hypothalamic PRLR mRNA concentrations in incubating hens were increased and decreased, respectively. In adult birds of either sex held on long or short days, there was no difference in pituitary PRLR mRNA, while basal hypothalamic PRLR mRNA was lower on short days. PRLR mRNA in the preoptic hypothalamus was not affected by sex, reproductive state, or photoperiod. It is concluded that there is no consistent relationship between plasma prolactin, in the physiological range, and the concentration of PRLR mRNA in the anterior pituitary gland, basal hypothalamus, and preoptic hypothalamus.

Aging↗
PubMed1995

Colocalization of dopamine and serotonin in the rat pituitary gland and in the nuclei innervating it.

The nerve terminals in the intermediate and posterior lobes of the rat pituitary gland are reported to show colocalization of serotonin and tyrosine hydroxylase. This study examined the extent of this colocalization in the pituitary gland and in the nuclei considered to project to the pituitary. In the intermediate lobe, two types of nerve fibers were encountered, one containing serotonin (5-HT-IR) and tyrosine hydroxylase (TH-IR) immunoreactivities and the other showing 5-HT-IR only. Instead, there was no colocalization in the posterior lobe. In the hypothalamus, colchicine treatment with L-tryptophan and pargyline injections resulted in 5-HT-IR in some neurons in the dorsomedial, periventricular and arcuate nuclei, some of which in the arcuate and periventricular nuclei were also TH-IR. In the raphe nuclei no colocalization of 5-HT-IR and TH-IR was observed. Catecholamine neurotoxin, 6-hydroxydopamine, abolished the 5-HT-IR and dramatically reduced the TH-IR in the intermediate lobe nerve fibers. Both effects were prevented by cocaine, a monoamine uptake inhibitor, but not by fluoxetine, a specific serotonin uptake inhibitor. Serotonin neurotoxin p-chloroamphetamine (PCA) had no effect on intermediate lobe fibers, although it caused complete disappearance of 5-HT-IR from the posterior lobe nerve fibers. This effect was prevented by fluoxetine. Our results indicate, that colocalization of serotonin and TH observed in the intermediate lobe occurs both in the nerve terminals within the lobe and in some nuclei that innervate it. Furthermore, drug treatments suggest that serotonin in the intermediate lobe is localized in catecholaminergic fibers, which do not posses a specific serotonin uptake mechanism.

Animals↗
PubMed2003

Effect of natriuretic peptides on in vitro stimulated adrenocorticotropic hormone release and pro-opiomelanocortin mRNA expression by the fetal rat pituitary gland in late gestation.

OBJECTIVE AND METHODS: We investigated the effects of individual natriuretic peptides (atrial natriuretic peptide, ANP; brain natriuretic peptide, BNP, and C-type natriuretic peptide, CNP) on rat corticotropin-releasing factor stimulated adrenocorticotropic hormone (ACTH) secretion by the pituitary gland of 21-day-old rat fetuses in vitro and on pro-opiomelanocortin gene expression using in situ hybridization. RESULTS: Graded concentrations of ANP, BNP, or CNP (10(-10), 10(-9), and 10(-8) mol/l) induced a log dose dependent inhibition of ACTH secretion induced by rat corticotropin-releasing factor (10(-10) mol/l). These natriuretic peptides showed equipotent effects on a molar basis. Moreover, ANP, BNP, or CNP at 10(-10) mol/l reduced significantly the pituitary pro-opiomelanocortin mRNA expression. In addition, the immunoreactive ANP, BNP, and CNP cells were localized in the anterior lobe, but not in the intermediate lobe of the fetal pituitary gland. CONCLUSIONS: These data suggest that the fetal pituitary gland may be both a source and a target for natriuretic peptides that might control ACTH synthesis and release via an endocrine and/or paracrine mechanism. The natriuretic peptides could participate, as well as glucocorticoids, in the control of the corticotropin-stimulating activity of the fetal rat in late gestation.

Adrenocorticotropic Hormone↗
PubMed2001

Expression and localization of leptin receptor in the normal rat pituitary gland.

Leptin receptor (leptin-R) is a polypeptide consisting of a single transmembrane-spanning component. Recent studies performed by reverse transcriptase polymerase chain reaction (RT-PCR) have shown the production of leptin-R in various tissues including the pituitary, hypothalamus and reproductive organs. The localization of leptin-R protein in the pituitary gland, however, has not been extensively studied. This study deals with the expression of leptin-R in the normal rat pituitary gland, which was disclosed primarily in the plasma membrane fraction by immunoblotting and immunohistochemical staining methods. Double immunohistochemical staining revealed that the colocalization of leptin-R and anterior pituitary hormone expression was seen mainly in growth hormone (GH)-secreting cells (97.4 +/- 1.3%; GH-positive cells/leptin-R-positive cells), but in less than 1% of prolactin (PRL)-, adrenocorticotropic hormone (ACTH)-, thyroid-stimulating hormone-beta (TSH beta)- and follicle-stimulating hormone-beta (FSH beta)/luteinizing hormone-beta (LH beta)-positive cells. In contrast, leptin was localized most frequently in FSH beta/LH beta- and less frequently in TSH beta-positive cells. The above findings suggest that, in the rat anterior pituitary gland, there are paracrine relationships between leptin-producing cells and cells with leptin-R, which may regulate the function of GH cells.

Adrenocorticotropic Hormone↗
PubMed1982

Ontogenesis of adrenocorticotropin-related peptide determinants in the hypothalamus and pituitary gland of the rat.

The time of appearance of the antigenic determinants of ACTH-related peptides (16K fragment, ACTH, gamma-lipoprotein, and beta-endorphin) was determined immunohistochemically in the brain and pituitary gland of the fetal rat. Major antigenic determinants of the pro-ACTH/endorphin precursor first appear in basally located cells of the hypothalamus on day 12 of gestation. Long axonal fibers are evident at day 13. Laterally located cells give rise to lateral, superficial fibers, whereas medially located cells give rise to periventricular fibers. The antigenic determinants appear simultaneously in the anterior lobe of the pituitary gland on day 16 and in the intermediate lobe on day 17. The intensity of immunostaining with anti-16K fragment antiserum is stronger than with the other antisera in the brain but is equal with other antisera in the pituitary. Neuronal perikarya always stain less intensely than pituitary cells. It is concluded that 1) ACTH-related antigenic determinants are produced within the central nervous system, and 2) cells containing ACTH-related antigenic determinants in pituitary gland and brain develop independently of one another.

Adrenocorticotropic Hormone↗
PubMed1989

Indomethacin inhibits the effects of oestrogen in the anterior pituitary gland of the rat.

Two inhibitors of prostaglandin synthesis, indomethacin and aspirin, blocked the increase of oestrogen-binding sites in the nuclear subcellular fraction, an increase which occurs after the administration of oestradiol. Consequently the biological effects of oestrogens in the anterior pituitary gland of the rat (prolactin synthesis, concentration of progesterone-binding sites and cell proliferation) are diminished. The anterior pituitary gland synthesized prostaglandin F2 alpha (PGF2 alpha), PGE2 and PGD2 from arachidonic acid. This synthesis was blocked when indomethacin was added to the culture media. Oestrogen increased the concentration of PGE2: an increase that was partially prevented by indomethacin. Prostaglandins may have an important role on the effects of oestrogen in the anterior pituitary gland of the rat.

Animals↗