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At least 343 records · Page 19Linked to original sources
PubMed1988

Incidence and characterization of age related amyloid deposits in the human anterior pituitary gland.

To identify amyloid deposits in the anterior pituitary gland, we have immunohistochemical, histochemical and alkaline Congo red staining. The anti-human P component reacted positively with these amyloid deposits, while antisera against prealbumin, AA type amyloid fibril protein and various anterior pituitary hormones were negative. A combination of Congo red and anti-human P component staining was most sensitive and reliable for detection of amyloid in the anterior pituitary glands of 300 randomly autopsied patients. Amyloid deposits increased in parallel with the age of the patients, however, they appeared earlier and more frequently than heretofore reported. Deposition of amyloid was seen initially in the 3rd decade and the positivity rate of amyloid deposits was 73% in the 5th decade. The histochemical characteristics of these pituitary amyloid deposits differed from those of cerebral and systemic deposits, particularly those found in the amyloid of senile systemic amyloidosis.

Adolescent↗
PubMed1983

[Sex and age differences in the spontaneous release of gonadotropins from immature rat pituitary glands in vitro].

The present study was carried out to characterize the spontaneous release of LH and FSH from the pituitary gland of infant rats in an in vitro system. In addition, the responsiveness of their pituitary glands to synthetic LHRH in vitro was examined. Wistar-Imamichi male and female rats, aged between 1 and 21 days and androgenized female rats at 7 and 21 days of age were used. One-day-old female rats were androgenized by a subcutaneous injection of 1 mg of testosterone propionate. Animals were killed by decapitation, trunk blood was collected, and the pituitary gland was dissected free and weighed. Pituitaries were placed in 9 ml-test tube with 2 ml Krebs-Henseleit solution and incubation was carried out in a shaking incubator for 6 hours at 37 degrees C under the gassing of 5% CO2 and 95% O2. After preincubation for 15 min, medium was replaced with 2 ml fresh medium and LH and FSH concentrations released during the first 3 hr-incubation period were assessed as for the spontaneous release and the second 3 hr-incubation period assessed for the response to LHRH (10(-6)M) stimulation. In an experiment, time course changes of the spontaneous release of LH and FSH were studied using 7-day-old rat pituitaries. An aliquot of 0.5 ml of medium was taken at 30, 60, 120 and 180 min during the incubation. Gonadotropin contents in the pituitaries were determined by adding the residue in the pituitary gland and the amounts released into medium. Spontaneous release of LH and FSH increased with age in both male and female rats, and the released amounts of LH as well as FSH in female rats tended to be higher than those in males at 1, 3, 7 and 21 days of age examined. But significant sex differences in the spontaneous release of LH and FSH were only seen at 21-day-old; Spontaneous release of LH in female rats was 7 times higher than that in age-matched males. Serum LH and FSH concentrations in female rats were significantly higher than those in males at all ages examined, except the LH level at 1-day-old. In contrast to LH, age and sex differences in the magnitude of the spontaneous release of FSH from the pituitary paralleled with the age and sex differences in serum FSH concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1988

Dynamic state of site-specific DNA methylation concurrent to altered prolactin and growth hormone gene expression in the pituitary gland of pregnant and lactating rats.

The regulatory mechanism for the hormonal control of prolactin (PRL) and growth hormone (GH) gene expression in rat pituitary gland during gestation and lactation is verified in this study. The level of PRL-specific mRNA (mRNAPRL) sequences in the pituitary gland is elevated in the later part of gestation and more prominently so in lactation. In contrast the expression of GH gene is inhibited in the same tissue during gestation and lactation resulting in the dramatic decrease in the level of GH-specific mRNA (mRNAGH) sequences. We now demonstrate the influence of a tissue-specific altered DNA methylation pattern on the temporal modulation of expression of PRL and GH genes in the pituitary gland during alternate physiological states. An altered methylation pattern of specific "-C-" residues only in the coding region of PRL and GH gene can be detected concurrently with the altered level of expression of these genes in the pituitary gland during gestation and lactation. These results also demonstrate the dynamic state of methylation of specific -C- residues during the transition of these two genes from one state of expression to another in the same tissue. A correlation between site-specific DNA methylation and tissue-specific expression of PRL and GH gene in pituitary gland is reported. Thus a role of DNA methylation in the hormonal control of PRL and GH gene expression in physiological states such as pregnancy and lactation is proposed.

Albumins↗
PubMed1982

Immunohistochemical localization of a human chorionic gonadotropin-like substance in the human pituitary gland.

A substance with the biological, immunological, and physicochemical properties similar to those of hCG (hCG-like substance) has been found in human pituitary homogenates and urine of nonpregnant subjects. The purpose of the present study was to localize the hCG-like substance in human pituitary gonadotropin producing cells (gonadotrophs) by using an unique antiserum raised against a synthetic hCG beta C-terminal peptide (P75R). Twenty-five pituitary glands were obtained at autopsy from women of various chronological ages. An immunohistochemical method was employed for localizing hLH, hFSH, and an hCG-like substance on the horizontal serial sections of the pituitary glands. The LH and FSH cells were indistinguishable with the antisera employed in the present study. The hCG-like substance was only localized in the cytoplasm of the gonadotrophs, rather commonly when the pituitary glands from postmenopausal women were examined. The P75R serum pretreated with excessive amount of native hCG failed to exhibit the immunostaining. Normal human tissues aside from pituitary glands did not react with the P75R serum. The results obtained in the present study and those reported by others may indicate that the hCG-like substance present in human pituitary glands is the precursor of hLH.

Adolescent↗
PubMed1981

Localization of 3H-dihydrotestosterone in the pituitary gland of the rhesus monkey.

The uptake and retention of radiolabelled dihydrotestosterone by the pituitary gland was examined in the rhesus monkey. Two animals were given an intravenous injection of 1.0 microgram/kg 3H-dihydrotestosterone (DHT) alone while one monkey received both the labelled androgen and 100 micrograms/kg of unlabelled steroid. One and a half hours later, they were sacrificed. The pituitary glands were removed and processed for autoradiography and immunocytochemistry. Autoradiographic localization of DHT was discernible in the partes nervosa, intermedia and distalis, albeit the highest concentration of radiolabelled cells was noted in the pars distalis. Immunocytochemical staining with antibodies to rat PRL, human TSH beta and ovine LH beta revealed a population of steroid-concentrating cells that contained TSH and a second group that contained LH. None of the cells that reacted with the anti-PRL serum were radiolabelled.

Animals↗
PubMed1983

Angiotensin-converting enzyme (kinase II) in pituitary gland of spontaneously hypertensive rats.

Angiotensin-converting enzyme (ACE) (kinase II; dipeptidyl carboxypeptidase, EC 3.4.15.1) activity was measured in pituitary gland of young (4-week-old) and adult (18-week-old) male, spontaneously hypertensive rats (SHR) and in age-matched normotensive male Wistar-Kyoto (WKY) control rats. In the three lobes of the pituitary gland ACE activity was significantly higher in young than in adult animals, in both SH and WKY rats. In the anterior lobe, ACE activity was lower in SHR when compared to age-matched Wistar-Kyoto controls. In contrast, ACE activity in the intermediate lobe of the pituitary gland was higher in SHR, and in particular in young animals. The observed differences between young WKY and SH rats in both the intermediate and anterior lobes did not appear to be due to a modified affinity of ACE for the substrate hippuryl-His-Leu, but to alterations in ACE maximal velocity or number of available molecules. No differences in ACE activity were detected between SHR and WKY rats in the posterior lobe. Total protein content was higher in the intermediate lobe and lower in the posterior lobe of young SHR when compared to normotensive controls. The present results suggest the possibility for a role of pituitary ACE in spontaneous (genetic) hypertension in rats.

Animals↗
PubMedDate not supplied

Perfusion MRI in normal and abnormal pituitary gland. A preliminary study.

Perfusion MRI (magnetic resonance imaging) of the pituitary gland was performed in 20 healthy volunteers and 63 patients with various lesions involving the pituitary gland. All patients underwent sequential contrast-enhanced MRI using spoiled gradient recalled sequences with high temporal resolution (7 seconds). Four pituitary areas (pituitary stalk, posterior lobe, postero-superior, and antero-inferior adenohypophysis) were tested with a selected region of interest. Maximal contrast percentual variation was calculated. The timing of enhancement in normal patients matched perfectly with normal pituitary vascularization. Abnormal timing in pathological condition was investigated.

Adenoma↗
PubMed2003

Postnatal differentiation of the immunohistochemical expression of aromatase P450 in the rat pituitary gland.

At our laboratory, we have recently demonstrated the immunohistochemical expression of aromatase P450 in the pituitary glands of adult rats; this expression was seen to be sex-dependent. In order to determine whether the changes in the expression of the enzyme are related to changes in the gonadal sphere and whether the expression of the enzyme is related to the postnatal differentiation of hypophyseal cytology, in the present work we performed an immunohistochemical study in the rat pituitary gland from birth to old age. The immunohistochemical reaction to aromatase was evident and very generalized at 7 days after birth, with no large differences between the male and female animals. At 14 days the immunohistochemical reaction was decreased in the females, with no changes in the males. At 17 days, aromatase immunoreactivity in the pituitary glands of female rats was very weak whereas the males showed large numbers of reactive cells. These observations were further pronounced at 21 days and 2 months of life. At 24 months, the immunoreactivity found in the pituitary glands of the male rats had almost completely disappeared. Our results show that a postnatal differentiation in the immunohistochemical expression of aromatase occurs; this is tightly linked to sexual activity and is lost in old age. This suggests that hypophyseal aromatase would be related to the mechanisms of action of gonadal steroids on hypophyseal differentiation and secretion.

Animals↗
PubMed1992

Detection of prolactin receptor (PRL-R) mRNA in the rat hypothalamus and pituitary gland.

Prolactin receptor (PRL-R) mRNAs exist in several tissues where prolactin is known to act including the liver, testes, prostate, ovary, mammary gland, adrenal gland and kidney. PRL also acts at the level of the hypothalamus and pituitary gland to feed back and regulate its own secretion and the secretion of other anterior pituitary hormones. Therefore, we hypothesized that PRL-R mRNA would exist in these target tissues as well. Total RNA was extracted from rat anterior and medial basal hypothalamus, anterior and posterior pituitary gland, cerebral cortex, skeletal muscle and liver. After reverse transcribing total RNA with Murine-MLV reverse transcriptase and random or oligo(dT) pmers, the polymerase chain reaction (PCR) was performed. PCR products were then analyzed by ethidium bromide staining. Using primers that flanked the coding region for the extracellular binding domain we detected PRL-R mRNA in the anterior and medial basal hypothalamus, anterior and posterior pituitary gland, as well as in the liver, but not in the cerebral cortex or skeletal muscle. In addition, when we used primers that distinguish the long and short forms of the PRL-R mRNA, both forms of the PRL-R mRNA were detectable in the same tissues. Our data suggest that PRL may feed back at the level of the hypothalamus and pituitary gland through the same short and/or long PRL-R mRNA that mediate PRL action in the peripheral tissues.

Animals↗
PubMed1980

The role of the pituitary gland in spontaneous canine mammary tumorigenesis.

The morphological changes of the pituitary gland of 29 female dogs with spontaneous mammary tumours or dysplasia or both were correlated with basal serum prolactin, growth hormone, adrenocorticotrophin, thyrotrophin, cortisol, total cholesterol, thyroxine and thyroid binding index as well as with lesions in other endocrine and genital organs. Spontaneous canine mammary tumorigenesis seemed to be associated with increased secretory activity of growth hormone rather than prolactin cells. Depressed secretory activity of follicle stimulating hormone-, luteinizing hormone- and thyrotrophin-producing cells, as well as signs of inhibition of ovarian (anovulation) and thyroid function, were also consistent findings in dogs with mammary tumours. There also was disturbance in pituitary-adrenal function associated with hyperplastic and neoplastic changes of the pituitary gland and adrenal cortex.

Animals↗
PubMed1985

Neurotensin-like immunoreactivity and neurotensin receptors in the rat hypothalamus and in the neurointermediate lobe of the pituitary gland.

In the rat hypothalamus, cell bodies containing neurotensin-like immunoreactivity were mainly found in the medial preoptic area, the periventricular nucleus, the paraventricular nucleus, the supraoptic nucleus and the arcuate nucleus. [3H]neurotensin binding sites were observed throughout the hypothalamus with a dense accumulation of silver grains over the paraventricular nucleus, the arcuate nucleus and the median eminence region. By radioimmunoassay neurotensin-like immunoreactivity was also found in the neurointermediate lobe of the pituitary gland of various mammalian species and in human postmortem posterior pituitary glands. In the rat studies involving pituitary stalk transections and the neurotoxin monosodium glutamate indicated the presence of a neurotensinergic pathway from the arcuate nucleus to the neurointermediate lobe of the pituitary gland. [3H]neurotensin binding sites were found to be concentrated over the intermediate lobe of the pituitary gland and their presence was not affected by pituitary stalk transection, indicating their localization on endocrine cells of the intermediate lobe of the pituitary gland.

Animals↗
PubMed2003

Regulation of genes encoding steroidogenic factor-1 (SF-1) and gonadotropin subunits in the ovine pituitary gland.

Steroidogenic factor-1 (SF-1) is a transcription factor originally characterized as a mediator of gene expression in steroidogenic tissues. Studies in SF-1 knockout mice revealed that SF-1 has additional roles at multiple levels of the hypothalamic-pituitary-gonadal axis, including regulation of gene expression in pituitary gonadotropes. Specific binding sites for SF-1 have been demonstrated in several pituitary genes with essential roles in gonadotropin synthesis, including alpha subunit, LHbeta subunit, and GnRH receptor. In studies aimed at identifying physiological factors controlling pituitary expression of SF-1, GnRH has been implicated as a co-regulator of SF-1 and gonadotropin subunit genes. In both rats and ewes, elevated endogenous secretion of GnRH following ovariectomy was associated with increased amounts of SF-1 mRNA in the anterior pituitary gland. Conversely, removal of GnRH input to the pituitary gland by hypothalamic-pituitary disconnection (HPD) in ovariectomized (OVX) ewes reduced SF-1 expression. Despite these changes, however, treatment of OVX ewes with GnRH following HPD only partially restored levels of SF-1 mRNA in the pituitary gland. Therefore, it is possible that regulation of SF-1 gene expression by GnRH during the estrous cycle may involve ovarian hormones or other hypothalamic factors. Additional studies are required to further define the physiological roles of SF-1 in regulation of the hypothalamic-pituitary-gonadal axis in domestic ruminants.

Animals↗
PubMed1994

The production of CINC/gro, a member of the interleukin-8 family, in rat anterior pituitary gland.

We investigated the possibility of detection of CINC/gro, which is a IL-8-like neutrophil chemoattractant, immunoreactivity in rat normal anterior pituitary gland by immunohistochemistry, western blot analysis and an ELISA. We first ascertained the possibility of detection of CINC/gro immunoreactivity in the anterior pituitary gland by immunocytochemistry. In the anterior lobe of the pituitary gland, a few CINC/gro-like immunoreactive cells were observed (1-3% of all cells in the anterior pituitary). The positive cells were middle or large in size and looked angular in shape. Intense immunoreactivity was observed in the cytoplasm but not in the nucleus. Analysis by immunoblotting with anti-CINC/gro antiserum gave a characteristic single CINC/gro band with a molecular weight of 6.3 kDa. CINC/gro immunoreactivity was also detected in 3-h conditioned medium of normal anterior pituitary cells by an ELISA, and that immunoreactivity increased significantly in a time-dependent manner during 24-h incubation. This immunoreactivity could be induced by TNF-alpha in a dose-dependent manner. These findings indicate that CINC/gro is produced in pituitary gland and also suggests the possibility that CINC/gro may play some role asa modulator of anterior pituitary function, especially in the cross-talk mechanism between the immune and neuroendocrine systems.

Analysis of Variance↗
PubMed1976

Inhibitory and augmentative effects of oestradiol on LH-RH-induced release of LH by anterior pituitary glands from intact female rats in vitro.

Anterior pituitary glands from intact dioestrous female rats were incubated in vitro and the LH released into the medium was measured at hourly intervals. The effect of a supramaximally active dose of LH-RH was first inhibited and later augmented by oestradiol added to the medium. The augmented response also occurred when LH-RH was absent during the preceding phase of the incubation. Both effects of oestradiol could be blocked by cycloheximide, which agent, however, also partly inhibited the response to LH-RH.

Animals↗
PubMed1977

Functional prenatal development of anencephalic and normal anterior pituitary glands. In human and experimental animals studied by peroxidase-labeled antibody method.

In order to investigate the influence of the central nervous system on the functional differentiation of the fetal anterior pituitary gland, the pituitary gland of anencephalic and normal fetus was studied by the peroxidase-labeled antibody method for the localization of various hormones. The only abnormality of pituitary endocrine cells in anencephaly was a marked decrease of ACTH cells. In the normal development, ACTH appeared as the earliest hormone in 5 weeks. And all other hormones were seen in 13 weeks. The reason for the decrease of ACTH cells in anencephaly was speculated to be a suppression at an early developmental life. The experimental observations done in rats using MAM might support this speculation. The adrenal glands of anencephalus showed atrophy of the fetal cortex which was considered to correlate with the decrease in number of ACTH cells. Absence of the histochemical activity of alkaline phosphatase in the permanent cortex of anencephaly may indicate absence or inadequate stimulation by fetal ACTH. Further experimental studies in suppression of the central nervous system in early developmental life seemed to confirm the above speculation in functional differentiation of the fetal pituitary and adrenal glands.

Adrenocorticotropic Hormone↗
PubMed1975

Ultrastructural observaitons of growth hormone (STH) cells of anterior pituitary glands of partially hepatectomized rats.

Ultrastructural changes in pituitary growth-hormone cells were observed in partially hepatectomized rats. The hepatectomies were carried out during the afternoon after 3 p.m. The animals were sacrificed by decapitation at midnight at intervals of 32, 80, and 104 hours after the operation. The principal changes in the growth-hormone cells of anterior pituitary glands of partially hepatectomized rats were: (1) increased numbers of secretory granules in exocytosis, (2) increased numbers of microtubules, and (3) enlargement of endoplasmic reticulum and occurrence of dilated cisternae of the endoplasmic reticula. Many growth-hormone cells contained a reduced number of secretory granules. Exocytosis of growth-hormone granules was more frequently observed in animals sacrificed at 32 hours after the operation than in those killed at 80 or 104 hours after surgery. The above results in which appearance of numerous microtubules and active secretory granule extrusion in the growth-hormone cells were observed after hepatectomy indicate that ultrastructure of growth-hormone cells and growth hormone secretion were markedly stimulated by the operation.

Animals↗