CLINICO-PATHOLOGICAL conference; arteriolar nephrosclerosis, atrophy of anterior pituitary gland.
Explore the source record for details and available documents.
Atrophy↗
SEARCH · Search PubMed
Results for “PITUITARY GLAND”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Intercellular communication within the rat anterior pituitary gland. II. Castration effects and changes after injection of luteinizing hormone-releasing hormone (LH-RH) or testosterone.
This study investigated the relationship between gap junction formation and sex steroids in the male rat anterior pituitary gland. Animals were castrated at 5 days of age and separated into the following three groups: 1) oil-treated controls, 2) those injected with LH-RH, and 3) those given testosterone. On days 10, 20, 30, and 40, five rats in each group were sacrificed and their hypophyses removed for ultrastructural examination. When compared with age-matched, intact animals, there was a marked suppression in follicular development and in the number of gap junctions present in the pituitary glands of both the castrated controls as well as the castrates given luteinizing hormone releasing hormone (LH-RH). In contrast, the morphology of these structures in the animals given testosterone was indistinguishable from that observed in the intact controls. These observations provide more definitive evidence that in the male rat pituitary gland maturation of the structural organization of the follicles, including gap junction formation, requires an intact hypophyseal-gonadal axis and is highly dependent on the hormone testosterone.
Animals↗
Prostaglandin D2 induces release of luteinizing hormone from the rat pituitary gland without the modulation of hypothalamic luteinizing hormone releasing hormone.
The effect of prostaglandin D2 (PGD2) on release of LH and LH releasing hormone (LHRH) was studied in a sequential double-chamber superfusion system using the medial basal hypothalamus (MBH) and the pituitary gland from female rats at dioestrus. Infusion of PGD2 (5.7 or 57 mumol/l) caused a significant (P less than 0.05) increase in LH release to values 40-60% above the preinjection values from the pituitary gland superfused either alone or in series with the MBH. No release of LHRH in response to PGD2 was observed from the superfused MBH. These data demonstrate that PGD2 causes LH release from the pituitary gland not by inducing release of hypothalamic LHRH but by a direct action on the gland.
Animals↗
Direct demonstration of guanine nucleotide sensitive receptors for vasoactive intestinal peptide in the anterior lobe of the rat pituitary gland.
The vasoactive intestinal peptide (VIP) receptors were identified on the membranes from the rat anterior pituitary gland with [125I]VIP. The dissociation constant (Kd) and the maximal binding capacity (Bmax) values were estimated from the competitive inhibition data. The Kd and Bmax values were 1.05 +/- 0.75 nM and 103 +/- 11 fmol/mg protein, respectively. The order of molar potency of related peptides to inhibit [125I]VIP binding was VIP greater than peptide histidine isoleucine (PHI) greater than secretin greater than glucagon. Glucagon was not effective to inhibit the binding. [125I]VIP binding was effectively inhibited by the addition of guanine nucleotides. The order of molar potency to inhibit the binding was Gpp(NH)p greater than GTP greater than GDP greater than GMP greater than ATP. These results directly suggest the coupling of VIP receptors with guanine nucleotide binding proteins in the anterior pituitary gland.
Animals↗
An "in vitro" model for combined functional and morphological investigations on the rat pituitary gland.
We have developed an alternative model for combined "in vitro" functional and morphological studies on the rat pituitary gland. To test its use for biochemical investigations we studied some aspects of the secretion in pituitary thyrotrophs under basal conditions and after stimulation with TRH. After stabilisation of basal TSH release, the stimulation with TRH significantly increased the TSH secretion. To test the usefulness of our model for morphological investigations the tissue was processed for conventional and immunocytochemical light and electron microscopy at the end of the incubation. Different types of pituitary cell resulted to be well preserved. Our model allows combined biochemical and morphological studies on the pituitary gland and thus reduces the number of animal groups, eliminates the extrapolation of results from different groups and replaces the "in vivo" by an "in vitro" experiment.
Animal Testing Alternatives↗
The prenatal pituitary gland--hidden and forgotten.
The sella turcica and pituitary gland in a human fetus (18 weeks gestation) with unilateral oro-ocular cleft combined with unilateral cleft lip and palate are described histologically. In this fetus the sella turcica was not a normal sella but a caudally open funnel. The adenopituitary gland tissue was positioned ectopically within the funnel canal and in the pharyngeal submucosa.
Abnormalities, Multiple↗
[Lactate dehydrogenase isoenzyme spectrum in the pituitary gland during changes in the functional state of the hypothalamo-pituitary-adrenal system].
Explore the source record for details and available documents.
Adrenalectomy↗
GABAA and GABAB receptor-mediated inhibition of release of 5-hydroxytryptamine in the intermediate lobe of the rat pituitary gland.
Isolated neurointermediate lobes or neural lobes of the rat pituitary gland attached to the pituitary stalk were incubated in vitro and the spontaneous or electrically (pituitary stalk stimulation, 5 Hz, 1,500 pulses) evoked release of 5-hydroxytryptamine was determined. The evoked release of 5-hydroxytryptamine from the neurointermediate lobe was increased fivefold in the presence of the dopamine receptor antagonist (-)-sulpiride (1 microM). The evoked release of 5-hydroxytryptamine from the isolated neural lobe was not altered by (-)-sulpiride. The evoked release of 5-hydroxytryptamine from the isolated neural lobe in the presence of (-)-sulpiride was less than 5% of that from the combined neurointermediate lobe showing that most of the 5-hydroxytryptamine released from the combined neurointermediate lobe originated in the intermediate lobe. The evoked release of 5-hydroxytryptamine from the neurointermediate lobe in the presence of (-)-sulpiride showed a diurnal variation. It was three to five times higher between 9.30 and 14.00 h than between 8.30 and 9.30 h or between 14.00 and 16.00 h. The 5-hydroxytryptamine tissue content at the end of the incubation experiments also showed similar variations which were, however, less pronounced. The evoked release of 5-hydroxytryptamine from the neurointermediate lobe, in the presence of (-)-sulpiride, was reduced by the preferential GABAA receptor agonist muscimol or the selective GABAB receptor agonist (-)-baclofen in a concentration-dependent manner. Bicuculline, a selective GABAA receptor antagonist inhibited the effect of muscimol, but not that of (-)-baclofen. Bicuculline alone did not affect the release of 5-hydroxytryptamine from the gland. It is concluded that the release of 5-hydroxytryptamine in the intermediate lobe is influenced by both dopaminergic and GABAergic mechanisms.
Animals↗
Action potentials in non-tumor cells from the anterior pituitary gland.
Non-tumor cells of rat anterior pituitary gland are able, upon electrical stimulation, to generate action potentials which are based on an increase of the membrane permeability to both Na+ and Ca2+.
Action Potentials↗
Developmental changes of Islet-1 and its co-localization with pituitary hormones in the pituitary gland of chick embryo by immunohistochemistry.
Although Islet-1 expression in the pituitary gland of early mouse embryo has been previously described, there are no reports concerning the correlation of Islet-1 expression with lineage restrictions in cell types at the later stages of pituitary development. The role of Islet-1 in chickens is also unknown. The purpose of this study was to follow, by using immunohistochemistry, the ontogeny of pituitary Islet-1 and the various cell types that contain Islet-1 throughout chick embryo development. A few Islet-1-immunopositive (Islet-1(+)) cells were first detected in the pituitary primordium in two out of six embryos at embryonic day 5.5 (E5.5), most of the Islet-1(+) cells being ventrally located. As development progressed, many more Islet-1(+) cells were observed throughout the pars distalis. The relative percentage of Islet-1(+) cells amongst the total Rathke's pouch cells was 4.4% at E6.5. This increased significantly, reaching 11.1% by E10.5, followed by no significant change until hatching. Dual immunohistochemistry showed that adrenocorticotrophs, somatotrophs and lactotrophs did not express Islet-1. The cellular types expressing Islet-1 included luteinizing-hormone-positive (LH(+)) gonadotrophs and thyroid-stimulating-hormone-positive (TSH(+)) thyrotrophs. The cells co-expressing LH and Islet-1 were initially detected at E6.5, the proportion of LH(+) cells possessing Islet-1 being about 4%; this increased to 63% at E14.5, followed by no significant changes until hatching. TSH and Islet-1 co-localized cells were first observed at E10.5, with about 37% TSH(+) cell expressing Islet-1; this increased to about 50% by E16.5, after which there was no evident change until hatching. These results suggest that Islet-1 is involved in determining the cell lineages, proliferation, differentiation and maintenance of hormone-secreting functions of pituitary gonadotrophs and thyrotrophs of chick embryo.
Animals↗
Pituitary gland and pregnancy.
The hypothalamic-pituitary-adrenal axis is central to mammalian reproductive function, including conception, pregnancy maintenance, parturition, and breastfeeding. Pregnancy is associated with substantial physiologic changes within this endocrine axis to meet the demands of pregnancy, which include support of the fetus (volume support, nutritional and oxygen supply, clearance of fetal waste), protection of the fetus (from starvation, drugs, toxins), preparation of the uterus for labor, and protection of the mother from potential cardiovascular injury at delivery. This article reviews the anatomy, embryology, and physiology of the pituitary. The effect of pregnancy on pituitary structure and function, in health and disease, also is discussed.
Female↗
Advances in neuroradiologic imaging of the pituitary gland: changing concepts.
A review of pituitary imaging is presented based on the history of neuroradiologic definition of the sellar contents as well as modern diagnostic techniques. The importance of normal pituitary and seller anatomy is stressed in an attempt to determine the limitations of defining abnormal sellar contents with the imaging techniques of computed tomography and magnetic resonance imaging. The sensitivity and specificity of these techniques are illustrated with histopathologic correlation.
Cerebrospinal Fluid↗
Fine structural features of secretion in adenomas of human pituitary gland.
Ultrastructural investigation of 274 human pituitary adenomas and 39 nontumorous adenohypophyses revealed two distinct types of secretion. Exocytosis was characteristic of prolactin cell adenomas, mixed growth hormone-prolactin cell adenomas, acidophil stem cell adenomas, and nontumorous prolactin cells. The second type, termed "transmembrane effusion," was noted in corticotroph, thyrotroph, gonadotroph, undifferentiated cell adenomas, and oncocytomas, as well as nontumorous corticotrophs, thyrotrophs, and gonadotrophs. It differed from that of prolactin cells and resembled diacrine secretion of gastrointestinal gastrin cells and membrane release in the neurohypophysis. In adenomatous and nontumorous growth hormone cells, neither exocytosis nor transmembrane effusion were apparent, hence a third type of release is suggested. Electron microscopic study of release mechanisms is helpful in the differential diagnosis of pituitary adenomas, since discharge of secretory products is not identical in the various tumor types.
Adenoma↗
Immunocytochemical localization of serotonin in the brain and pituitary gland of the platyfish, Xiphophorus maculatus.
Immunoreactive serotonin (ir-5HT) containing cells were localized in the brain and pituitary gland of the platyfish by use of immunoperoxidase procedures. In the brain, ir-neurons were found lining the wall of the third ventricle and in its lateral and posterior recesses. More caudally, ir-perikarya were found in the valvular portion of the cerebellum and in the raphe region. Ir-5HT was also localized within the pineal gland in fish that had been sacrificed before 1:00 p.m. Within the pituitary gland, ir-5HT was localized in periodic acid Schiff-positive cells of the pars intermedia of all fish while, in only a few animals, less intense immunoreactivity was also present in gonadotrophs of the caudal pars distalis.
Animals↗
Size heterogeneity of prolactin secreted from and stored in the rat anterior pituitary gland in vitro.
The size heterogeneity of rat pituitary prolactin was investigated using anterior pituitary glands from female rats incubated in vitro and gel filtration on Sephadex G-100. Monomeric prolactin was preferentially secreted compared with dimeric and 'trimeric' material. When glands were incubated with dopamine, prolactin secretion was inhibited and the relative proportion of dimer in the gland (but not the medium) was decreased. Morphine sulphate reversed the effect of dopamine on prolactin secretion and on the proportion of prolactin in the gland that was in the dimeric form. The results suggest that monomeric prolactin is more readily secreted than dimer, and that dopamine decreases the production or stability of the dimer.
Animals↗
Effects of N-nitroso-N-methylurea on mammary and pituitary glands of young female Sprague-Dawley rats.
Female Sprague-Dawley rats aged 50 days received 3 intravenous injections of N-nitroso-N-methylurea, 5 mg/100 g of body weight at 4 weekly intervals. When the first palpable mammary tumours appeared, with an incidence of 50 to 60% after the third injection, rats were randomized into 8 groups: group 1 was treated with 17 beta-estradiol; group 2 received progesterone; group 3 received in association 17 beta-estradiol + progesterone; group 4 was treated with tamoxifen. In group 5, rats received ovine prolactin. In groups 6 and 7, female rats were bred. Group 8, as a control group, received no hormonal treatment. Other control groups of 8 rats aged 140 days were made up of rats receiving 17 beta-estradiol alone (group 9) and rats receiving only ovine prolactin (group 10). The last group was kept without any treatment (group 11). The incidence of mammary tumours was followed in groups 1 to 8. All pituitary glands and mammary tumours were removed and weighed when rats were sacrificed after the last hormonal injection in each group. Light microscopy allowed the anatomopathologist to classify all removed mammary tumours in each group as adenocarcinoma. Light and electron microscopies with all pituitary glands in groups 1 to 11 showed no abnormality. The distribution of the pituitary weights was between 4.0 to 6.8 mg per 100 g of body weight. No adenomas were detected in the pituitary glands of the 5-month-old Sprague-Dawley rats receiving N-nitroso-N-methylurea.
Adenocarcinoma↗
Lisuride, a dopamine agonist, inhibits DNA synthesis in the pituitary gland.
We investigated the effects of lisuride, a potent dopaminergic agent, administered in vivo on the incorporation of 3H-thymidine into DNA and 3H-leucine into prolactin and its subsequent release by the rat anterior pituitary gland in vitro. The results demonstrated that daily injection of 100 micrograms of lisuride for 7 days significantly (p less than 0.05) diminished (about 35%) the incorporation of 3H-thymidine into DNA and reduced the stimulation of DNA synthesis produced by estrogens. The incorporation of 3H-leucine into prolactin was markedly inhibited by the administration of lisuride, and also significantly (p less than 0.05) reduced the stimulation of prolactin secretion produced by estrogens. In pituitary glands enlarged by the chronic administration of estrogens, lisuride treatment significantly (p less than 0.05) reduced the weight (26%), the content of DNA (35%) and the incorporation of 3H-thymidine (40%). The inhibitory effect of lisuride on DNA synthesis was present as early as 20 h after a single injection of the drug (about 27%). The same treatment with lisuride significantly (p less than 0.05) reduced the incorporation of 3H-leucine into prolactin. The results of these experiments are compatible with the concept of a relationship between prolactin release and DNA synthesis in the pituitary gland. They also suggest that lisuride, as with bromocriptine, may exert its antiproliferative effects on prolactin-secreting adenomas by decreasing their synthesis of DNA.
Animals↗
Endothelin-1 binding to endothelin receptors in the rat anterior pituitary gland: possible formation of an ETA-ETB receptor heterodimer.
1. Interaction in the recognition of endothelin-1 (ET-1), a typical bivalent ET receptor-ligand, between ETA and ETB receptors was investigated in the rat anterior pituitary gland, using our quantitative receptor autoradiographic method with tissue sections preserving the cell-membrane structure and ET receptor-related compounds. 2. In saturation binding studies with increasing concentrations (0.77-200 pM) of 125I-ET-1 (nonselective bivalent radioligand), 125I-ET-1 binding to the rat anterior pituitary gland was saturable and single with a KD of 71 pM and a Bmax of 120 fmol mg(-1). When 1.0 microM BQ-123 (ETA antagonist) was added to the incubation buffer, binding parameters were 8.3 pM of KD and 8.0 fmol mg(-1) of Bmax, whereas 10 nM sarafotoxin S6c (ETB agonist) exerted little change in these binding parameters (KD, 72 pM; Bmax, 110 fmol mg(-1)). 3. Competition binding studies with a fixed amount (3.8 pM) of 125 I-ET-1 revealed that when 1.0 microM BQ-123 was present in the incubation buffer, ETB receptor-related compounds such as sarafotoxin S6c, ET-3, IRL1620 (ETB agonist), and BQ-788 (ETB antagonist) competitively inhibited 125I-ET-1 binding with K(i)s of 140,18,350 pM, and 14 nM, respectively, however, these compounds were not significant competitors for 125I-ET-1 binding in the case of absence of BQ-123. 4. In cold-ligand saturation studies with a fixed amount (390 pM) of 125I-IRL 1620 (ETB radioligand), IRL1620 bound to a single population of the ETB receptor, and no change was observed in binding characteristics in the presence of 1.0 microM BQ-123. 125I-IRL1620 binding was competitively inhibited by ET-1 and ET-3 in the absence of BQ-123, with K(i)s of 20 and 29 pM, respectively, the affinities being much the same as those of 29 nM, in the presence of 1.0 microM BQ-123. 5. Two nonbivalent ETA antagonists, BQ-123 and PD151242, were highly sensitive and full competitors for 125I-ET-1 binding (5.0 pM), in the presence of 10 nM sarafotoxin S6c. 6. Taken together with the present finding that mRNAs encoding the rat ETA and the ETB receptors are expressed in the anterior pituitary gland, we tentatively conclude that although there are ETA and ETB receptors with a functional binding capability for ET receptor-ligands, the ETB receptor does not independently recognize ET-1 without the aid of the ETA receptor. If this thesis is tenable, then ET-1 can bridge between the two receptors to form an ETA-ETB receptor heterodimer.
Animals↗