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Pituitary Gland (pituitary + gland)
Kinds of Pituitary Gland Selected AbstractsRegion-Specific Expression and Hormonal Regulation of the First Exon Variants of Rat Prolactin Receptor mRNA in Rat Brain and Anterior Pituitary GlandJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2007H. Nogami Recent studies have revealed the occurrence of five first exon variants of the rat prolactin receptor mRNA, suggesting that multiple promoters direct prolactin receptor transcription in response to different regulatory factors. In the present study, regional expression of these first exon variants, as well as two prolactin receptor subtypes generated by alternative splicing, was examined in the brains and anterior pituitary glands of female rats. Expression of the long-form was detected in the choroid plexus, hypothalamus, hippocampus, cerebral cortex and anterior pituitary gland, whereas the short form was detected only in the choroid plexus. E1-3 mRNA, a first exon variant, was detected in the choroid plexus, hypothalamus, and anterior pituitary gland, whereas E1-4 was detected only in the choroid plexus. Other variants were not detectable by the polymerase chain reaction protocol employed in this study. Ovariectomy increased the short form in the choroid plexus and the E1-3 expression in the choroid plexus and pituitary gland, but changes in the long-form and E1-4 expression were minimal. Replacement of oestrogens and prolactin suggest that oestrogens down-regulate E1-3 expression in the choroid plexus and pituitary gland, and that the negative effect of oestrogen is mediated by prolactin in the pituitary gland. The present results revealed the region-specific promoter usage in prolactin receptor mRNA transcription, as well as the involvement of oestrogens in the regulation of E1-3 mRNA expression in the brain and pituitary gland. [source] Islet-1 Expression and its Colocalisation with Luteinising Hormone, Thyroid-Stimulating Hormone and Oestrogen Receptor Alpha in the Developing Pituitary Gland of the Sheep FoetusJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2005J. Liu Abstract Islet-1 has been reported to be involved in pituitary development in the early stages of mouse embryogenesis. Oestrogen receptor (ER) and its expression may be involved in regulating pituitary development and its hormone-secreting function. Islet-1 expression and its correlations to ER in the developing pituitary gland are unknown. We therefore determined the pituitary cell specific expression of Islet-1 and its colocalisation with ER alpha (ER,) in sheep foetus by immunohistochemistry. The results demonstrated that Islet-1-immunoreacitive (ir) cells were distributed throughout the pituitary gland from day 60 of gestation until birth. The Islet-1-ir cell number was significant higher at day 90 and 120 of gestation compared to that at day 60 and at birth. All of the ER,-ir cells were colocalised with Islet-1 at day 60 of gestation, although a few ER,-ir cells were negative for Islet-1 in the later stage of gestation. The dominant cell type expressing Islet-1 is the gonadotroph, although small proportions of thyrotrophs and lactotrophs also express Islet-1. The proportion of luteinising hormone-ir gonadotrophs possessing Islet-1 kept rising from day 60 to day 120 of gestation and persisted until birth. The proportion of thyroid-stimulating hormone-ir cells expressing Islet-1 was at a high level from day 60,120 of the gestation and significantly declined at birth. The percentage of prolactin (PRL)-ir cells expressing Islet-1 was about 20% at day 60 of gestation. Very few PRL-ir cells contained Islet-1 in later stages of gestation. These data suggest that the development and functional establishment of pituitary gonadotrophs, thyrotrophs and lactotrophs might be regulated by the expressions of Islet-1 and ER, and by their interactions, although any mechanisms need to be elucidated further. [source] Gonadotroph Heterogeneity, Density and Distribution, and Gonadotroph,Lactotroph Associations in the Pars Distalis of the Male Equine Pituitary GlandJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2004J. Townsend Abstract The intrapituitary mechanisms regulating gonadotrophin secretion in the horse remain unclear. Here, we examined seasonal and gonadal effects on the gonadotroph and lactotroph populations of male horses with the aim of defining a possible morphological basis for the differential release of gonadotrophins. Pituitaries were collected from: (i) gonadal-intact horses in the breeding season (GBS); (ii) orchidectomized horses in the breeding season (OBS); and (iii) orchidectomized horses in the nonbreeding season (ONBS). Immunohistochemistry was performed using antibodies to the luteinizing hormone (LH) , subunit, follicle-stimulating hormone (FSH) , subunit and prolactin. In all groups, gonadotrophs were distributed throughout the pars distalis, with dense populations detected near the borders with the pars tuberalis and pars intermedia. The numbers of LH-monohormonal, FSH-monohormonal and bihormonal cells/field were greater in GBS than in OBS and ONBS horses. Similarly, the proportion of gonadotrophs in relation to all pituitary cells was larger in gonadal-intact than orchidectomized horses. In the absence of the gonads, no effects of season were observed on these variables. Interestingly, the relative proportions of gonadotroph subtypes and the LH/FSH gonadotroph ratio were similar among groups. Furthermore, while specific gonadotroph,lactotroph associations were identified in all groups, significant gonadal effects within the breeding season and direct effects of season within orchidectomized horses were detected for the number of lactotrophs. This study reveals a gonadal-independent effect of season on the lactotroph, but not the gonadotroph population of the equine pituitary, and a clear gonadal stimulation of both cell types within the breeding season. We suggest that alterations in intercellular arrangements, rather than changes in the incidence of gonadotroph subtypes, may contribute to the differential release of gonadotrophins and, accordingly, to the intrapituitary control of fertility throughout the male equine annual reproductive cycle. [source] Detailed Visualization of the Functional Regions of the Rat Pituitary Gland by High-Resolution T2-Weighted MRIANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2010E. Theunissen With 5 figures and 1 table Summary This high-resolution MRI study focuses on the visualization of the detailed morphology of the rat's pituitary gland by means of post-mortem as well as in vivo MRI at 9.4 T. Determination of the local T1- and T2-relaxation decay times allows to explain the regional image intensities which reflects the degree of tissue organization at the molecular level. Detailed characterization of the molecular level of the pituitary gland, as provided by the relaxation decay times, can offer a rigid platform with respect to functional or pathological explorations. It is demonstrated that T1-weighted imaging, as is routinely used in the clinic, can differentiate between the posterior and anterior lobe but not between the posterior and intermediate lobe. T2-weighted images, however, clearly show the three distinct lobes of the rat pituitary gland without the use of contrast agents, i.e. the posterior, the intermediate and the anterior lobe. Histological analysis of the rat's pituitary gland confirms the morphological structures seen on the MR images. Although the intermediate lobe is less defined in humans and can neither be differentiated by T1-weighted MRI, its clinical visualization might be possible in T2-weighted images. [source] Social Stress Alters Expression of Large Conductance Calcium-Activated Potassium Channel Subunits in Mouse Adrenal Medulla and Pituitary GlandsJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2009O. Chatterjee Large conductance calcium-activated potassium (BK) channels are very prominently expressed in adrenal chromaffin and many anterior pituitary cells, where they shape intrinsic excitability complexly. Stress- and sex-steroids regulate alternative splicing of Slo-,, the pore-forming subunit of BK channels, and chronic behavioural stress has been shown to alter Slo splicing in tree shrew adrenals. In the present study, we focus on mice, measuring the effects of chronic behavioural stress on total mRNA expression of the Slo-, gene, two key BK channel , subunit genes (,2 and ,4), and the ,STREX' splice variant of Slo-,. As a chronic stressor, males of the relatively aggressive SJL strain were housed with a different unfamiliar SJL male every 24 h for 19 days. This ,social-instability' paradigm stressed all individuals, as demonstrated by reduced weight gain and elevated corticosterone levels. Five quantitative reverse transcriptase-polymerase chain assays were performed in parallel, including ,-actin, each calibrated against a dilution series of its corresponding cDNA template. Stress-related changes in BK expression were larger in mice tested at 6 weeks than 9 weeks. In younger animals, Slo-, mRNA levels were elevated 44% and 116% in the adrenal medulla and pituitary, respectively, compared to individually-housed controls. ,2 and ,4 mRNAs were elevated 162% and 194% in the pituitary, but slightly reduced in the adrenals of stressed animals. In the pituitary, dominance scores of stressed animals correlated negatively with , and , subunit expression, with more subordinate individuals exhibiting levels that were three- to four-fold higher than controls or dominant individuals. STREX variant representation was lower in the subordinate subset. Thus, the combination of subunits responding to stress differs markedly between adrenal and pituitary glands. These data suggest that early stress will differentially affect neuroendocrine cell excitability, and call for detailed analysis of functional consequences. [source] Pituitary mRNA Expression of the Growth Hormone Axis in the 1-Year-Old Intrauterine Growth Restricted RatJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2006T. Prins Intrauterine growth restriction (IUGR) is one of the major causes of short stature in childhood. Abnormalities in the growth hormone (GH) axis have frequently been observed in children who are born intrauterine growth restricted and GH treatment is effective to improve final height. However, the way that the GH axis is involved is not fully understood. Previously, when investigating the effect of IUGR on the central somatotrophic axis, a hypothalamic effect was discovered with elevated somatostatin and decreased neuropeptide Y mRNA expression levels, whereas serum GH and insulin-like growth factor I (IGFI) were unaltered. These findings were thought to indicate a hypothalamic alteration of the GH axis due to IUGR, probably to compensate pituitary output, thereby normalising peripheral values of GH and IGFI. Therefore, the present study aimed to evaluate the effect of IUGR on the pituitary GH axis in this rat model. Pups from rats that underwent bilateral uterine artery ligation at day 17 of pregnancy were studied. Pituitary glands were collected from 1-year-old offspring for quantitative measurements of GH, GH-receptor (GH-R), GH-releasing hormone receptor (GHRH-R), somatostatin receptor subtype 2 and 5, IGFI and IGFI receptor mRNA levels using a real-time reverse transcriptase-polymerase chain reaction. In addition, liver GH-R and IGFI mRNA expression levels were measured and a radioimmunoassay was performed to determine serum IGFI levels. In the IUGR rat, levels of pituitary GH, GH-R and GHRH-R relative gene expression (RGE) were increased. No differences were found in the RGE level of all other pituitary growth factors, liver GH-R and IGFI, and serum IGFI concentration between IUGR and control rats. The present data show that intrauterine growth failure leads to changes in the pituitary that might counterbalance the effects found previously in the hypothalamus. [source] WNT signaling affects gene expression in the ventral diencephalon and pituitary gland growthDEVELOPMENTAL DYNAMICS, Issue 4 2008Mary Anne Potok Abstract We examined the role of WNT signaling in pituitary development by characterizing the pituitary phenotype of three WNT knockout mice and assessing the expression of WNT pathway components. Wnt5a mutants have expanded domains of Fgf10 and bone morphogenetic protein expression in the ventral diencephalon and a reduced domain of LHX3 expression in Rathke's pouch. Wnt4 mutants have mildly reduced cell differentiation, reduced POU1F1 expression, and mild anterior lobe hypoplasia. Wnt4, Wnt5a double mutants exhibit an additive pituitary phenotype of dysmorphology and mild hypoplasia. Wnt6 mutants have no obvious pituitary phenotype. We surveyed WNT expression and identified transcripts for numerous Wnts, Frizzleds, and downstream pathway members in the pituitary and ventral diencephalon. These findings support the emerging model that WNT signaling affects the pituitary gland via effects on ventral diencephalon signaling, and suggest additional Wnt genes that are worthy of functional studies. Developmental Dynamics 237:1006,1020, 2008. © 2008 Wiley-Liss, Inc. [source] Mast cells and their role in the neuro-immune-endocrine axisEXPERIMENTAL DERMATOLOGY, Issue 9 2004J. Bienenstock It has become clear that the immune and nervous systems communicate constantly to maintain homeostasis and a coordinated and continuing adaptive response to an ever-changing environment. Evidence from mast cell nerve communication, as an example of this interaction, has been obtained in a variety of tissues and circumstances, most especially in the intestine and skin. Bidirectional communication has been shown in vivo, ex vivo, in vitro and in coculture experiments involving the two cell types. Examples will be given of these various situations and involve normal physiological situations and those involved in response to infection and inflammation as well as in response to ultraviolet light. More recent examples of the importance of mast cells in the regulation of central nervous activity including the secretion of hormones by the pituitary gland, and thereby the regulation of the HPA axis as well as involvement in behavioural change will be addressed. Through its potential communication with the nervous system, the mast cell can be regarded as a sentinel cell or receptor, especially located at surfaces exposed to the environment, which specifically and non-specifically react to molecules and substances, foreign to the organism, so as to help orchestrate the complex and integrated responses required to maintain homeostasis. [source] Cocaine- and amphetamine-regulated transcript (CART) peptide as an in vivo regulator of cardiac function in Rana ridibunda frogEXPERIMENTAL PHYSIOLOGY, Issue 6 2007Iliyana V. Ivanova The aim of this study was to investigate the effect of CART peptide on cardiac performance and on the physiological signalling pathways involved using Rana ridibunda frog heart preparations in vivo. The CART peptide, when injected into the venous sinus, significantly and reproducibly increased the force of frog heart contractions by up to 33.0 ± 6.4% during the first 15 min after its application but did not influence the chronotropic activity of the frog heart. The positive inotropic effect was entirely blocked by prazosin, pertussis toxin, Rp -adenosine 3,,5,-cyclic monophosphorothioate, autosauvagine 30 or metyrapone, as well as by extirpation of the pituitary gland, functional elimination of the inter-renal glands and long-lasting starvation, and was not observed on isolated heart preparations. Propranolol and double pithing were without significant effect on this phenomenon. It was concluded that: (i) CART peptide, administered to frogs in vivo, increases the force of heart contractions; (ii) this effect of the peptide is exerted via activation of the hypothalamic,pituitary,inter-renal gland axis through a corticoliberin-sensitive mechanism; (iii) CART augments the pumping function of the heart via a corticosteroid-dependent potentiation of myocardial ,1 -adrenoreceptors signalling; and (iv) prolonged food deprivation abolishes the positive inotropic effect of CART, suggesting the participation of endogenous CART in the physiological adaptation of the circulatory system to limitations of energy consumption. [source] Cell type-specific transgene expression of the prion protein in Xenopus intermediate pituitary cellsFEBS JOURNAL, Issue 4 2006Jos W. G. Van Rosmalen The cellular form of prion protein (PrPC) is anchored to the plasma membrane of the cell and expressed in most tissues, but predominantly in the brain, including in the pituitary gland. Thus far, the biosynthesis of PrPC has been studied only in cultured (transfected) tumour cell lines and not in primary cells. Here, we investigated the intracellular fate of PrPCin vivo by using the neuroendocrine intermediate pituitary melanotrope cells of the South-African claw-toed frog Xenopus laevis as a model system. These cells are involved in background adaptation of the animal and produce high levels of its major secretory cargo proopiomelanocortin (POMC) when the animal is black-adapted. The technique of stable Xenopus transgenesis in combination with the POMC gene promoter was used as a tool to express Xenopus PrPC amino-terminally tagged with the green fluorescent protein (GFP,PrPC) specifically in the melanotrope cells. The GFP,PrPC fusion protein was expressed from stage-25 tadpoles onwards to juvenile frogs, the expression was induced on a black background and the fusion protein was subcellularly located mainly in the Golgi apparatus and at the plasma membrane. Pulse,chase metabolic cell labelling studies revealed that GFP,PrPC was initially synthesized as a 45-kDa protein that was subsequently stepwise glycosylated to 48-, 51-, and eventually 55-kDa forms. Furthermore, we revealed that the mature 55-kDa GFP,PrPC protein was sulfated, anchored to the plasma membrane and cleaved to a 33-kDa product. Despite the high levels of transgene expression, the subcellular structures as well as POMC synthesis and processing, and the secretion of POMC-derived products remained unaffected in the transgenic melanotrope cells. Hence, we studied PrPC in a neuroendocrine cell and in a well-defined physiological context. [source] Cre-mediated recombination in pituitary somatotropesGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2009Igor O. Nasonkin Abstract We report a transgenic line with highly penetrant cre recombinase activity in the somatotrope cells of the anterior pituitary gland. Expression of the cre transgene is under the control of the locus control region of the human growth hormone gene cluster and the rat growth hormone promoter. Cre recombinase activity was assessed with two different lacZ reporter genes that require excision of a floxed stop sequence for expression: a chick ,-actin promoter with the CMV enhancer transgene and a ROSA26 knock-in. Cre activity is detectable in the developing pituitary after initiation of Gh transcription and persists through adulthood with high penetrance in Gh expressing cells and lower penetrance in lactotropes, a cell type that shares a common origin with somatotropes. This Gh-cre transgenic line is suitable for efficient, cell-specific deletion of floxed regions of genomic DNA in differentiated somatotropes and a subset of lactotrope cells of the anterior pituitary gland. genesis 47:55,60, 2009. © 2008 Wiley-Liss, Inc. [source] Cre-mediated recombination in cell lineages that express the progesterone receptorGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 2 2005Selma M. Soyal Abstract Using gene-targeting methods, a progesterone receptor Cre knockin (PR-Cre) mouse was generated in which Cre recombinase was inserted into exon 1 of the PR gene. The insertion positions the Cre gene downstream (and under the specific control) of the endogenous PR promoter. As for heterozygotes for the progesterone receptor knockout (PRKO) mutation, mice heterozygous for the Cre knockin insertion are phenotypically indistinguishable from wildtype. Crossing the PR-Cre with the ROSA26R reporter revealed that Cre excision activity is restricted to cells that express PR in progesterone-responsive tissues such as the uterus, ovary, oviduct, pituitary gland, and mammary gland. Initial characterization of the PR-Cre mouse underscores the utility of this model to precisely ablate floxed target genes specifically in cell lineages that express the PR. In the wider context of female reproductive tissue ontology, this model will be indispensable in tracing the developmental fate of cell lineages that descend from PR positive progenitors. genesis 41:58,66, 2005. © 2005 Wiley-Liss, Inc. [source] Neuroendocrine mechanisms controlling female puberty: new approaches, new conceptsINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 1 2006Sergio R. Ojeda Summary Sexual development and mature reproductive function are controlled by a handful of neurones that, located in the basal forebrain, produce the decapeptide luteinizing hormone releasing hormone (LHRH). LHRH is released into the portal system that connects the hypothalamus to the pituitary gland and act on the latter to stimulate the synthesis and release of gonadotrophin hormones. The pubertal activation of LHRH release requires coordinated changes in excitatory and inhibitory inputs to LHRH-secreting neurones. These inputs are provided by both transsynaptic and glia-to-neurone communication pathways. Using cellular and molecular approaches, in combination with transgenic animal models and high-throughput procedures for gene discovery, we are gaining new insight into the basic mechanisms underlying this dual control of LHRH secretion and, hence, the initiation of mammalian puberty. Our results suggest that the initiation of puberty requires reciprocal neurone-glia communication involving excitatory amino acids and growth factors, and the coordinated actions of a group of transcriptional regulators that appear to represent a higher level of control governing the pubertal process. [source] Comparison of intensity modulated radiation therapy (IMRT) treatment techniques for nasopharyngeal carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 2 2001Jason Chia-Hsien Cheng M.D. Abstract We studied target volume coverage and normal tissue sparing of serial tomotherapy intensity modulated radiation therapy (IMRT) and fixed-field IMRT for nasopharyngeal carcinoma (NPC), as compared with those of conventional beam arrangements. Twelve patients with NPC (T2-4N1-3M0) at Mallinckrodt Institute of Radiology underwent computed tomography simulation. Images were then transferred to a virtual simulation workstation computer for target contouring. Target gross tumor volumes (GTV) were primary nasopharyngeal tumor (GTVNP) with a prescription of 70 Gy, grossly enlarged cervical nodes (GTVLN) with a prescription of 70 Gy, and the uninvolved cervical lymphatics [designated as the clinical tumor volume (CTV)] with a prescription of 60 Gy. Critical organs, including the parotid gland, spinal cord, brain stem, mandible, and pituitary gland, were also delineated. Conventional beam arrangements were designed following the guidelines of Intergroup (SWOG, RTOG, ECOG) NPC Study 0099 in which the dose was prescribed to the central axis and the target volumes were aimed to receive the prescribed dose ± 10%. Similar dosimetric criteria were used to assess the target volume coverage capability of IMRT. Serial tomotherapy IMRT was planned using a 0.86-cm wide multivane collimator, while a dynamic multileaf collimator system with five equally spaced fixed gantry angles was designated for fixed-beam IMRT. The fractional volume of each critical organ that received a certain predefined threshold dose was obtained from dose-volume histograms of each organ in either the three-dimensional or IMRT treatment planning computer systems. Statistical analysis (paired t -test) was used to examine statistical significance. We found that serial tomotherapy achieved similar target volume coverage as conventional techniques (97.8 ± 2.3% vs. 98.9 ± 1.3%). The static-field IMRT technique (five equally spaced fields) was inferior, with 92.1 ± 8.6% fractional GTVNP receiving 70 Gy ± 10% dose (P < 0.05). However, GTVLN coverage of 70 Gy was significantly better with both IMRT techniques (96.1 ± 3.2%, 87.7 ± 10.6%, and 42.2 ± 21% for tomotherapy, fixed-field IMRT, and conventional therapy, respectively). CTV coverage of 60 Gy was also significantly better with the IMRT techniques. Parotid gland sparing was quantified by evaluating the fractional volume of parotid gland receiving more than 30 Gy; 66.6 ± 15%, 48.3 ± 4%, and 93 ± 10% of the parotid volume received more than 30 Gy using tomotherapy, fixed-field IMRT, and conventional therapy, respectively (P < 0.05). Fixed-field IMRT technique had the best parotid-sparing effect despite less desirable target coverage. The pituitary gland, mandible, spinal cord, and brain stem were also better spared by both IMRT techniques. These encouraging dosimetric results substantiate the theoretical advantage of inverse-planning IMRT in the management of NPC. We showed that target coverage of the primary tumor was maintained and nodal coverage was improved, as compared with conventional beam arrangements. The ability of IMRT to spare the parotid glands is exciting, and a prospective clinical study is currently underway at our institution to address the optimal parotid dose-volume needs to be spared to prevent xerostomia and to improve the quality of life in patients with NPC. © 2001 Wiley-Liss, Inc. [source] Immunocytochemical studies of the gonadotropic cells in the pituitary gland of male mullet, Mugil cephalus, during the annual reproductive cycle in both natural habitat and captivityJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2000M. A. Mousa Summary Using antiserum specific for the , subunit of coho salmon gonadotropic hormone II (GTH II), an immunocytochemical study of Mugil cephalus (L.) pituitaries was conducted during the annual reproductive cycle of the male in both natural habitat and captivity. The gonadotropic potency of the pituitary gland in general underwent an obvious increase during testicular development, reaching a peak at the time of reproductive maturity. During the testicular cycle of M. cephalus, the GTH cells showed an increase in immunoreactive staining intensity, granulation, hypertrophy and hyperplasia during sexual maturation. However, degranulation, vacuolization, and weakened immunoreactivity of these cells occurred during spawning. The GTH cells in the pituitary gland of M. cephalus males reared in captivity appeared with high synthetic and secretory activity but the reproductive activity declined, as reflected in the form of low values of the gonadosomatic index (GSI) and earlier resorption of the testes. [source] In vivo measurements of T1 relaxation times in mouse brain associated with different modes of systemic administration of manganese chlorideJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2005Yu-Ting Kuo MD Abstract Purpose To measure regional T1 and T2 values for normal C57Bl/6 mouse brain and changes in T1 after systemic administration of manganese chloride (MnCl2) at 9.4 T. Materials and Methods C57Bl/6 mice were anesthetized and baseline T1 and T2 measurements obtained prior to measurement of T1 after administration of MnCl2 at 9.4 T. MnCl2 was administered systemically either by the intravenous (IV), intraperitoneal (IP), or subcutaneous (SC) routes. T1 and T2 maps for each MRI transverse slice were generated using commercial software, and T1 and T2 values of white matter (WM), gray matter (GM), pituitary gland, and lateral ventricle were obtained. Results When compared with baseline values at low-field, significant lengthening of the T1 values was shown at 9.4 T, while no significant change was seen for T2 values. Significant T1 shortening of the normal mouse brain was observed following IV, IP, and SC administration of MnCl2, with IV and IP showing similar acute effects. Significant decreases in T1 values were seen for the pituitary gland and the ventricles 15 minutes after either IV or IP injection. GM showed greater uptake of the contrast agent than WM at 15 and 45 minutes after either IV or IP injections. Although both structures are within the blood-brain barrier (BBB), GM and WM revealed a steady decrease in T1 values at 24 and 72 hours after MnCl2 injection regardless of the route of administration. Conclusion Systemic administration of MnCl2 by IV and IP routes induced similar time-course of T1 changes in different regions of the mouse brain. Acute effects of MnCl2 administration were mainly influenced by either the presence or absence of BBB. SC injection also provided significant T1 change at subacute stage after MnCl2 administration. J. Magn. Reson. Imaging 2005;21:334,339. © 2005 Wiley-Liss, Inc. [source] Expression of a Rho Guanine Nucleotide Exchange Factor, Ect2, in the Developing Mouse PituitaryJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2010M. S. Islam The pituitary gland is a highly mitotically active tissue after birth. Various cell types are known to undergo proliferation in the anterior pituitary. However, little is known about the mechanisms regulating mitotic activity in this tissue. When searching for genes specifically expressed in the pituitary gland among those that we previously screened in Drosophila, we found epithelial cell-transforming gene 2 (Ect2). Ect2 is a guanine nucleotide exchange factor for Rho GTPases, which is known to play an essential role in cytokinesis. Although there have been many cellular studies regarding the function of Ect2, the temporal and spatial expression patterns of Ect2 in vivo have not been determined. In the present study, we examined the postnatal developmental expression of Ect2 in the mouse pituitary. Enhanced Ect2 expression was detected in the mouse pituitary gland during the first 3 weeks after birth, which coincided well with the period of rapid pituitary expansion associated with increased growth rate. Immunostaining analysis showed that Ect2-expressing cells were distributed in the anterior and intermediate lobes, but not the posterior lobe, of the pituitary. These Ect2-expressing cells frequently incorporated the thymidine analogue, EdU (5-ethynyl-2,-deoxyuridine), indicating that these cells were mitotically active. Taken together, the results demonstrate the functional role of Ect2 in postnatal proliferating cells in the two lobes of the pituitary, thereby suggesting roles in developmental growth of the mammalian pituitary. [source] Bovine Anterior Pituitary Progenitor Cell Line Expresses Interleukin (IL)-18 and IL-18 ReceptorJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2008Y. Nagai In the anterior pituitary gland, inflammatory mediators regulate cell function through an immuno-endocrine pathway. Recent studies have shown that undifferentiated stem cells act as immunomodulators. These studies prompted us to establish a progenitor cell line from the bovine anterior pituitary gland and to detail its function. First, we localised interleukin (IL)-18 by immunohistochemistry to the marginal cell layer of Rathke's pouch that is assumed to embody a stem/progenitor cell compartment of the postnatal pituitary gland. A cloned anterior pituitary-derived cell line from the bovine anterior pituitary gland was established from single cell clone by the limiting dilution method and was designated as bovine anterior pituitary-derived cell line (BAPC)-1. BAPC-1 cells constantly expressed mRNAs for IL-18 and IL-18 receptor, and grew steadily and rapidly in the medium containing epidermal growth factor and basic fibroblast growth factor. The cell line also expressed the mRNAs for the stem/progenitor cell- related factors such as Nanog, Oct-4, Ptch1, Nestin, Notch1, Hes1, Lrp and Fzd4, and the mRNAs for embryonic pituitary-related factors, such as Lhx3, PitX1 and Pit-1. The nuclei of BAPC-1 were immunostained positively for Pit-1, Hes1 and ,-catenin antibodies. Furthermore, BAPC-1 cells expressed mRNAs for cytokine such as IL-1,, IL-6, IL-7, IL-12 and IL-15. Stimulation of BAPC-1 cells with IL-18 increased expression of mRNAs for IL-1,, IL-6, IL-1, and IL-8. At day 6 in culture, BAPC-1 cells also express growth hormone mRNA. These results strongly suggest that BAPC-1 is a stem/progenitor cell line and modulates the immuno-endocrine function of the anterior pituitary cells through its cytokine production. [source] An Insight to Pituitary Folliculo-Stellate CellsJOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2008S. Devnath Folliculo-stellate cells (FS-cells) are star-shaped and follicle-forming cells in the anterior pituitary gland that were first identified by electron microscopy as non-endocrine agranular cells. Light microscopy has revealed many of their cytophysiological features and the FS-cell is known to be positive for S-100 protein, a marker for FS-cells. So far, functions ascribed to FS-cells include the formation of an extensive and complex tridimentional network, scavenger activity by engulfing degenerated cells, paracrine regulation of endocrine cells by producing various growth factors and cytokines, such as interleukin-6, leukemia inhibitory factor, basic fibroblastic growth factor, vascular endothelial cell growth factor and follistatin, and large-scale inter-cellular communication by means of their long cytoplasmic processes and gap junctions. Moreover, their multi-potential characteristics and other cytological features support the possibility of them becoming organ-specific stem cells. This concept is yet to be resolved, however. In this review, we focus on these features of FS-cells along with some futuristic approaches. [source] Region-Specific Expression and Hormonal Regulation of the First Exon Variants of Rat Prolactin Receptor mRNA in Rat Brain and Anterior Pituitary GlandJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2007H. Nogami Recent studies have revealed the occurrence of five first exon variants of the rat prolactin receptor mRNA, suggesting that multiple promoters direct prolactin receptor transcription in response to different regulatory factors. In the present study, regional expression of these first exon variants, as well as two prolactin receptor subtypes generated by alternative splicing, was examined in the brains and anterior pituitary glands of female rats. Expression of the long-form was detected in the choroid plexus, hypothalamus, hippocampus, cerebral cortex and anterior pituitary gland, whereas the short form was detected only in the choroid plexus. E1-3 mRNA, a first exon variant, was detected in the choroid plexus, hypothalamus, and anterior pituitary gland, whereas E1-4 was detected only in the choroid plexus. Other variants were not detectable by the polymerase chain reaction protocol employed in this study. Ovariectomy increased the short form in the choroid plexus and the E1-3 expression in the choroid plexus and pituitary gland, but changes in the long-form and E1-4 expression were minimal. Replacement of oestrogens and prolactin suggest that oestrogens down-regulate E1-3 expression in the choroid plexus and pituitary gland, and that the negative effect of oestrogen is mediated by prolactin in the pituitary gland. The present results revealed the region-specific promoter usage in prolactin receptor mRNA transcription, as well as the involvement of oestrogens in the regulation of E1-3 mRNA expression in the brain and pituitary gland. [source] Is Reproductive Ageing Controlled By the Brain?JOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2007Andrea C. Gore Summary Female reproductive function is controlled by complex interactions of the brain, pituitary gland and ovary. Each of these organs produces unique hormones, and each hormone acts upon the other organs to affect a response. Differentiating the causes and the consequences of reproductive senescence in mammals is thus a ,chicken and egg' puzzle. Surprisingly, recent evidence indicates a more important role for the brain in the initiation and transition to reproductive senescence. [source] Pituitary Transcription Factors: From Congenital Deficiencies to Gene TherapyJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2006M. H. Quentien Despite the existence of interspecies phenotypic variability, animal models have yielded valuable insights into human pituitary diseases. Studies on Snell and Jackson mice known to have growth hormone, prolactin and thyroid-stimulating hormone deficiencies involving the hypoplastic pituitary gland have led to identifying alterations of the pituitary specific POU homeodomain Pit-1 transcription factor gene. The human phenotype associated with rare mutations in this gene was found to be similar to that of these mice mutants. Terminal differentiation of lactotroph cells and direct regulation of the prolactin gene both require interactions between Pit-1 and cell type specific partners, including panpituitary transcriptional regulators such as Pitx1 and Pitx2. Synergistic activation of the prolactin promoter by Pitx factors and Pit-1 is involved not only in basal condition, but also in responsiveness to forskolin, thyrotrophin-releasing-hormone and epidermal growth factor. In corticotroph cells, Pitx1 interacts with Tpit. Tpit mutations have turned out to be the main molecular cause of neonatal isolated adrenocorticotrophin deficiency. This finding supports the idea that Tpit plays an essential role in the differentiation of the pro-opiomelanocortin pituitary lineage. The effects of Pit-1 are not restricted to hormone gene regulation because this factor also contributes to cell division and protects the cell from programmed cell death. Lentiviral vectors expressing a Pit-1 dominant negative mutant induced time- and dose-dependent cell death in somatotroph and lactotroph adenomas in vitro. Gene transfer by lentiviral vectors should provide a promising step towards developing an efficient specific therapeutic approach by which a gene therapy programme for treating human pituitary adenomas could be based. [source] Reproduction Phase-Related Expression of ,-Endorphin-Like Immunoreactivity in the Nucleus Lateralis Tuberis of the Female Indian Major Carp Cirrhinus mrigala: Correlation with the Luteinising Hormone Cells-Ovary AxisJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2006A. J. Sakharkar Abstract The present study aimed to determine whether ,-endorphin immunoreactivity (bEP-ir) in the neurones of the nucleus lateralis tuberis (NLT) is linked to the seasonal cycle and shows correlation with the number of luteinising hormone (LH) cells in the pituitary gland and ovaries in the teleost, Cirrhinus mrigala. Although LH cells were moderately immunostained during the resting phase (December to January), the morphological profile suggested increased synthetic and secretory activity during the preparatory (February to April) and prespawning (May to June) phases. However, LH immunoreactivity was greatly reduced (P < 0.001) in the spawning (July to August) phase, suggesting massive discharge of the hormone; this pool was partly replenished in the postspawning (September to November) phase. The ovaries grew rapidly in the preparatory and prespawning phases; maximal size was attained during spawning, when ovulation occurred. Thereafter, the ovaries regressed. The NLT of C. mrigala is divisible into the pars lateralis (NLTl) and medialis (NLTm). During the postspawning and resting phases, bEP-ir was readily detectable in the NLTm as well as NLTl neurones. However, a steady reduction in the immunoreactivity was observed in the NLTm neurones during the preparatory through spawning phases (P < 0.001), suggesting a negative correlation with the LH cells-ovary axis. Thus, the inhibitory influence of ,-endorphin on the gonadotrophin-releasing hormone (GnRH)-LH axis appears to be attenuated during the preparatory through spawning phases. This may be necessary for the rapid stimulation of the axis culminating in spawning. Neurones of the NLTl also showed a gradual reduction in bEP-ir during the preparatory and prespawning phases (P < 0.01) and may therefore play a similar role. However, significant augmentation of the immunoreactivity was noticed in these neurones during the spawning phase (P < 0.001), the physiological significance of which is unknown. Although the present study demonstrated a temporal correlation between the ,-endorphin in the NLT, LH cells and the ovary, we suggest that the peptide in the NLTl and NLTm may show functional duality during the spawning phase. [source] Islet-1 Expression and its Colocalisation with Luteinising Hormone, Thyroid-Stimulating Hormone and Oestrogen Receptor Alpha in the Developing Pituitary Gland of the Sheep FoetusJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2005J. Liu Abstract Islet-1 has been reported to be involved in pituitary development in the early stages of mouse embryogenesis. Oestrogen receptor (ER) and its expression may be involved in regulating pituitary development and its hormone-secreting function. Islet-1 expression and its correlations to ER in the developing pituitary gland are unknown. We therefore determined the pituitary cell specific expression of Islet-1 and its colocalisation with ER alpha (ER,) in sheep foetus by immunohistochemistry. The results demonstrated that Islet-1-immunoreacitive (ir) cells were distributed throughout the pituitary gland from day 60 of gestation until birth. The Islet-1-ir cell number was significant higher at day 90 and 120 of gestation compared to that at day 60 and at birth. All of the ER,-ir cells were colocalised with Islet-1 at day 60 of gestation, although a few ER,-ir cells were negative for Islet-1 in the later stage of gestation. The dominant cell type expressing Islet-1 is the gonadotroph, although small proportions of thyrotrophs and lactotrophs also express Islet-1. The proportion of luteinising hormone-ir gonadotrophs possessing Islet-1 kept rising from day 60 to day 120 of gestation and persisted until birth. The proportion of thyroid-stimulating hormone-ir cells expressing Islet-1 was at a high level from day 60,120 of the gestation and significantly declined at birth. The percentage of prolactin (PRL)-ir cells expressing Islet-1 was about 20% at day 60 of gestation. Very few PRL-ir cells contained Islet-1 in later stages of gestation. These data suggest that the development and functional establishment of pituitary gonadotrophs, thyrotrophs and lactotrophs might be regulated by the expressions of Islet-1 and ER, and by their interactions, although any mechanisms need to be elucidated further. [source] Magnetic Resonance Imaging of the Hypothalamic-Neurohypophyseal SystemJOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2004I. Fujisawa Abstract Magnetic resonance imaging (MRI) is a revolutionary advance in diagnostic imaging of the hypothalamic-neurohypophyseal system (HNS). The detailed anatomy of the sellar and parasellar region is clearly visible using MRI, because it has no bony artifacts and multidirectional capability. The posterior lobe of the pituitary gland displays a characteristic bright signal on the MR T1-weighted image (T1WI), and is distinctly separated from the anterior lobe. The bright signal is absent in patients with central diabetes insipidus, and is thought to reflect normal vasopressin storage in the posterior lobe. The signal intensity ratio of the posterior lobe to the pons on T1WI is strongly correlated with vasopressin content in the posterior lobe. In addition to the morphological evaluation, MRI provides unique information concerning the function of the HNS. The MRI findings of the HNS (normal condition, central diabetes insipidus, a depleted posterior lobe, an ectopic posterior lobe, and a damming-up phenomenon of the neurosecretory vesicles in the pituitary stalk) are demonstrated in this article. [source] Gender Differences in the Expression of Galanin and Vasoactive Intestinal Peptide in Oestrogen-Induced Prolactinomas of Fischer 344 RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2004G. G. Piroli Abstract We have previously described a sexual dimorphism in oestrogen-induced anterior pituitary tumorigenesis in Fischer 344 rats, with female tumours averaging twice the size of those of males. Neonatal androgenization of female Fischer 344 rats with 100 µg of testosterone propionate reverted that effect, causing a ,male-like' phenotype. The peptides galanin and vasoactive intestinal peptide (VIP) are possible mediators of oestrogen effects on the anterior pituitary, including hyperprolactinemia and lactotroph proliferation. To further extend our previous findings, we investigated the expression of galanin and VIP in the anterior pituitary of control and oestrogenized male, female and neonatally androgenized female Fischer 344 rats. At 3 months of age, rats were deprived of their gonads and divided into control and diethylstilbestrol (DES)-treated groups. In the anterior pituitary of control rats, galanin and VIP immunoreactive cells were absent. However, in DES-treated rats, pituitaries from normal ovariectomized females showed higher number of galanin and VIP positive cells than pituitaries from neonatally androgenized ovariectomized females and gonadectomized males. This pattern correlated with changes in anterior pituitary weight and serum prolactin. Our study suggests that sexual differences in oestrogen-induced pituitary tumorigenesis could be due to the differential expression of galanin and VIP. Furthermore, our data support the fact that neonatal exposure to androgens, as in normal males and androgenized females, may condition the response of the pituitary gland to oestrogens in adult life. [source] Gonadotropin-Inhibitory Peptide in Song Sparrows (Melospiza melodia) in Different Reproductive Conditions, and in House Sparrows (Passer domesticus) Relative to Chicken-Gonadotropin-Releasing HormoneJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2003G. E. Bentley Abstract Gonadotropin-releasing hormone (GnRH) regulates reproduction in all vertebrates. Until recently, an antagonistic neuropeptide for gonadotropin was unknown. The discovery of an RFamide peptide in quail that inhibits gonadotropin release in vitro raised the possibility of direct hypothalamic inhibition of gonadotropin release. This peptide has now been named gonadotropin-inhibitory hormone (GnIH). We investigated GnIH presence in the hypothalamus of two seasonally breeding songbird species, house sparrows (Passer domesticus) and song sparrows (Melospiza melodia). Using immunocytochemistry (ICC), GnIH-containing neurones were localized in both species in the paraventricular nucleus, with GnIH-containing fibres visible in multiple brain locations, including the median eminence and brainstem. Double-label ICC with light microscopy and fluorescent ICC with confocal microscopy indicate a high probability of colocalization of GnIH with GnRH neurones and fibres within the avian brain. It is plausible that GnIH could be acting at the level of the hypothalamus to regulate gonadotropin release as well as at the pituitary gland. In a photoperiod manipulation experiment, GnIH-containing neurones were larger in birds at the termination of the breeding season than at other times, consistent with a role for this neuropeptide in the regulation of seasonal breeding. We have yet to elucidate the dynamics of GnIH synthesis and release at different times of year, but the data imply temporal regulation of this peptide. In summary, GnIH has the potential to regulate gonadotropin release at more than one level, and its distribution is suggestive of multiple regulatory functions in the central nervous system. [source] Cocaine- and Amphetamine-Regulated Transcript is Present in Hypothalamic Neuroendocrine Neurones and is Released to the Hypothalamic-Pituitary Portal CircuitJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2003P. J. Larsen Abstract Cocaine- and amphetamine-regulated transcript (CART) is present in a number of hypothalamic nuclei. Besides actions in circuits regulating feeding behaviour and stress responses, the hypothalamic functions of CART are largely unknown. We report that CART immunoreactivity is present in hypothalamic neuroendocrine neurones. Adult male rats received a systemic injection of the neuronal tracer Fluorogold (FG) 2 days before fixation, and subsequent double- and triple-labelling immunoflourescence analysis demonstrated that neuroendocrine CART-containing neurones were present in the anteroventral periventricular, supraoptic, paraventricular (PVN) and periventricular nuclei of the hypothalamus. In the PVN, CART-positive neuroendocrine neurones were found in all of cytoarchitectonically identified nuclei. In the periventricular nucleus, approximately one-third of somatostatin cells were also CART-immunoreactive. In the medial parvicellular subnucleus of the PVN, CART and FG coexisted with thyrotrophin-releasing hormone, whereas very few of the corticotrophin-releasing hormone containing cells were CART-immunoreactive. In the arcuate nucleus, CART was extensively colocalized with pro-opiomelanocortin in the ventrolateral part, but completely absent from neuroendocrine neurones of the dorsomedial part. To assess the possible role of CART as a hypothalamic-releasing factor, immunoreactive CART was measured in blood samples from the long portal vessels connecting the median eminence with the anterior pituitary gland. Adult male rats were anaesthetized and the infundibular stalk exposed via a transpharyngeal approach. The long portal vessels were transected and blood collected in 30-min periods (one prestimulatory and three poststimulatory periods). Compared to systemic venous plasma samples, baseline concentrations of immunoreactive CART were elevated in portal plasma. Exposure to sodium nitroprusside hypotension triggered a two-fold elevation of portal CART42-89 immunoreactivity throughout the 90-min stimulation period. In contrast, the concentration of portal plasma CART immunoreactivity dropped in the vehicle infused rats. The current study provides further evidence that CART is a neuroendocrine-releasing factor with a possible impact on anterior pituitary function during states of haemodynamic stress. [source] Targeted Cytotoxic Analogue of Luteinizing Hormone-Releasing Hormone (LH-RH) Only Transiently Decreases the Gene Expression of Pituitary Receptors for LH-RHJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2002M. Kovacs Abstract A cytotoxic analogue of LH-RH, AN-207, consisting of 2-pyrrolinodoxorubicin (AN-201) linked to carrier [D-Lys6]LH-RH, was developed for targeted therapy of cancers expressing LH-RH-receptors. To determine its possible side-effects on the pituitary gland, we investigated the gene expression of pituitary LH-RH-receptors and LH secretion in ovariectomized female and normal male rats after treatment with the maximum tolerated dose of AN-207. The effect of AN-207 on the gene expression of the pituitary GH-RH-receptors and GH secretion was also assessed in male rats. Five hours after a single i.v. injection of AN-207 at 175 nmol/kg, there was a 39,51% decrease in mRNA expression for the pituitary LH-RH-receptors in male and female rats. The carrier, at an equimolar dose, caused a similar reduction (37,39%), whereas the cytotoxic radical AN-201, at an equitoxic dose (110 nmol/kg), produced only a 12,24% decrease (NS) in the mRNA expression of LH-RH-receptors. AN-207 and the carrier analogue induced a comparable 90,100-fold increase in serum LH concentrations in male rats, and the same 12-fold elevation in OVX rats at 5 h. Seven days after treatment with AN-207, the mRNA levels for the LH-RH receptors and the serum LH concentration were back to normal in both sexes. AN-207, the carrier, and AN-201 had no significant effect on the expression of mRNA for GH-RH-receptors in the pituitary. In vitro, a continuous perfusion of pituitary cells with 10 nM AN-207 did not affect the hormone-releasing function of the targeted LH cells or the nontargeted GH cells. Our results demonstrate that cytotoxic LH-RH analogue AN-207, at the maximum tolerated dose causes only a transient decrease in the gene expression of the pituitary LH-RH receptors, and the levels of mRNA for LH-RH receptor fully recover within 7 days. Moreover, the carrier hormone moiety, and not the cytotoxic radical in AN-207 is responsible for this transient suppression. Our findings suggest that the therapy with cytotoxic LH-RH analogues will not inflict permanent damage to pituitary function. [source] The Pars Tuberalis: The Missing Link in the Photoperiodic Regulation of Prolactin Secretion?JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2000Morgan The endocrine function of the pars tuberalis of the pituitary gland has been an enigma for many years. Recent work suggests that one of its primary functions in seasonal mammals is to mediate photoperiodically regulated changes in prolactin secretion via an unidentified factor called tuberalin. [source] | ||||||||||||||||||||||||||||