Home About us Contact
|
Home About us Contact | ||
|
|
||
Neurosecretory Cells (neurosecretory + cell)
Kinds of Neurosecretory Cells Selected AbstractsExpression of GABAB Receptors in Magnocellular Neurosecretory Cells of Male, Virgin Female and Lactating RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2005D. S. Richards Abstract GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABAB receptors in magnocellular neurones in the SON and PVN. Robust GABAB receptor immunoreactivity (GABABR; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABABR immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABABR immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABABR was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABABR immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABAB receptors in magnocellular neurosecretory cells. [source] Brain-derived neurotrophic factor-like neuropeptide is secreted as a neurohormone from specific brain neurons into the corpus allatum in the silkworm Bombyx moriENTOMOLOGICAL RESEARCH, Issue 1 2006Mi Young KIM Abstract The aim of this study was to investigate the secretion of brain-derived neurotrophic factor (BDNF)-like neuropeptide in the silkworm, Bombyx mori , by using immunocytochemical techniques on the brain and retrocerebral complex of fifth instar larvae. In the brain, four pairs of median neurosecretory cell (MNC) bodies and six pairs of lateral neurosecretory cell (LNC) bodies had distinct immunoreactivities to this peptide, suggesting that this peptide is produced from two types of brain neuron. These reactivities were much stronger in the MNC than in the LNC. Labeled MNC projected their axons into the contralateral corpora allata, to which axons of labeled MNC were eventually innervated, through decussation in the median region, contralateral nerve corporis cardiaci I and nerve corpora allata I. Labeled LNC extended their axons into the ipsilateral corpora allata to be innervated through the ipsilateral nerve corporis cardiaci II and nerve corpora allata I. These results suggest that BDNF is secreted as a neurohormone from MNC and LNC of the brain into the corpora allata. [source] Glucose-induced inhibition: how many ionic mechanisms?ACTA PHYSIOLOGICA, Issue 3 2010D. Burdakov Abstract Sensing of sugar by specialized ,glucose-inhibited' cells helps organisms to counteract swings in their internal energy levels. Evidence from several cell types in both vertebrates and invertebrates suggests that this process involves sugar-induced stimulation of plasma membrane K+ currents. However, the molecular composition and the mechanism of activation of the underlying channel(s) remain controversial. In mouse hypothalamic neurones and neurosecretory cells of the crab Cancer borealis, glucose stimulates K+ currents displaying leak-like properties. Yet knockout of some of the candidate ,leak' channel subunits encoded by the KCNK gene family so far failed to abolish glucose inhibition of hypothalamic cells. Moreover, in other tissues, such as the carotid body, glucose-stimulated K+ channels appear to be not leak-like but voltage-gated, suggesting that glucose-induced inhibition may engage multiple types of K+ channels. Other mechanisms of glucose-induced inhibition, such as hyperpolarization mediated by opening of Cl, channels and depolarization block caused by closure of KATP channels have also been proposed. Here we review known ionic and pharmacological features of glucose-induced inhibition in different cell types, which may help to identify its molecular correlates. [source] Myocyte enhancer factor 2 (MEF2) is a key modulator of the expression of the prothoracicotropic hormone gene in the silkworm, Bombyx moriFEBS JOURNAL, Issue 15 2005Kunihiro Shiomi Prothoracicotropic hormone (PTTH) plays a central role in controlling molting, metamorphosis, and diapause termination in insects by stimulating the prothoracic glands to synthesize and release the molting hormone, ecdysone. Using Autographa californica nucleopolyhedrovirus (AcNPV)-mediated transient gene transfer into the central nervous sytem (CNS) of the silkworm, Bombyx mori, we identified two cis -regulatory elements that participate in the decision and the enhancement of PTTH gene expression in PTTH-producing neurosecretory cells (PTPCs). The cis -element mediating the enhancement of PTTH gene expression binds the transcription factor Bombyx myocyte enhancer factor 2 (BmMEF2). The BmMEF2 gene was expressed in various tissues including the CNS. In brain, the BmMEF2 gene was expressed at elevated levels in two types of lateral neurosecretory cells, namely PTPCs and corazonin-like immunoreactive lateral neurosecretory cells. Overexpression of BmMEF2 cDNA caused an increase in the transcription of PTTH. Therefore, BmMEF2 appears to be particularly important in the brain where it is responsible for the differentiation of lateral neurosecretory cells, including the enhancement of PTTH gene expression. This is the first report to identify a target gene of MEF2 in the invertebrate nervous system. [source] Age- and division-of-labour-dependent differential expression of a novel non-coding RNA, Nb-1, in the brain of worker honeybees, Apis mellifera L.INSECT MOLECULAR BIOLOGY, Issue 6 2009H. Tadano Abstract To elucidate the molecular mechanisms underlying honeybee social behaviours, we identified a novel gene, Nb-1, whose expression in the worker brain changes according to the age-dependent division of labour in normal colonies. The open reading frames contained in the Nb-1 cDNA were not conserved in the homologue of a related species, suggesting that the Nb-1 gene product is a non-coding RNA. The distribution of Nb-1- expressing cells partially overlapped that of octopamine-immunoreactive cells and neurosecretory cells, the latter of which are involved in the synthesis and secretion of juvenile hormone (JH). Octopamine and JH control worker task transition, and thus Nb-1 might be involved in task transition through the modulation of octopamine/JH synthesis and secretion. [source] DILP-producing median neurosecretory cells in the Drosophila brain mediate the response of lifespan to nutritionAGING CELL, Issue 3 2010Susan J. Broughton Summary Dietary restriction extends lifespan in diverse organisms, but the gene regulatory mechanisms and tissues mediating the increased survival are still unclear. Studies in worms and flies have revealed a number of candidate mechanisms, including the target of rapamycin and insulin/IGF-like signalling (IIS) pathways and suggested a specific role for the nervous system in mediating the response. A pair of sensory neurons in Caenorhabditis elegans has been found to specifically mediate DR lifespan extension, but a neuronal focus in the Drosophila nervous system has not yet been identified. We have previously shown that reducing IIS via the partial ablation of median neurosecretory cells in the Drosophila adult brain, which produce three of the seven fly insulin-like peptides, extends lifespan. Here, we show that these cells are required to mediate the response of lifespan to full feeding in a yeast dilution DR regime and that they appear to do so by mechanisms that involve both altered IIS and other endocrine effects. We also present evidence of an interaction between these mNSCs, nutrition and sleep, further emphasising the functional homology between the DILP-producing neurosecretory cells in the Drosophila brain and the hypothalamus of mammals in their roles as integration sites of many inputs for the control of lifespan and behaviour. [source] Electrophysiological Identification of the Functional Presynaptic Nerve Terminals on an Isolated Single Vasopressin Neurone of the Rat Supraoptic NucleusJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2010T. Ohbuchi Release of arginine vasopressin (AVP) and oxytocin from magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) is under the control of glutamate-dependent excitation and GABA-dependent inhibition. The possible role of the synaptic terminals attached to SON neurones has been investigated using whole-cell patch-clamp recording in in vitro rat brain slice preparations. Recent evidence has provided new insights into the repercussions of glial environment modifications on the physiology of MNCs at the synaptic level in the SON. In the present study, excitatory glutamatergic and inhibitory GABAergic synaptic inputs were recorded from an isolated single SON neurone cultured for 12 h, using the whole-cell patch clamp technique. Neurones expressed an AVP-enhanced green fluorescent protein (eGFP) fusion gene in MNCs. In addition, native synaptic terminals attached to a dissociated AVP-eGFP neurone were visualised with synaptic vesicle markers. These results suggest that the function of presynaptic nerve terminals may be evaluated directly in a single AVP-eGFP neurone. These preparations would be helpful in future studies aiming to electrophysiologically distinguish between the functions of synaptic terminals and glial modifications in the SON neurones. [source] Expression of GABAB Receptors in Magnocellular Neurosecretory Cells of Male, Virgin Female and Lactating RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2005D. S. Richards Abstract GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABAB receptors in magnocellular neurones in the SON and PVN. Robust GABAB receptor immunoreactivity (GABABR; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABABR immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABABR immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABABR was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABABR immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABAB receptors in magnocellular neurosecretory cells. [source] Rhythmogenesis in Vasopressin CellsJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2004C. H. Brown Abstract Many neurones in the central nervous system possess intrinsic pattern-generating properties, including vasopressin magnocellular neurosecretory cells. Synaptic input to vasopressin cells is not rhythmically patterned and yet these neurones fire action potentials in a ,phasic' activity pattern comprised of alternating periods of activity and silence that each last tens of seconds. This review describes the intrinsic and extrinsic mechanisms that generate phasic activity in vasopressin cells, highlighting recent work that has shown phasic activity to result from feedback modulation of synaptic inputs, and of intrinsic membrane properties, by peptides released from the dendrites of vasopressin cells. [source] Histological and immunocytochemical localization of serotonin-like immunoreactivity in the brain and optic ganglia of the Indian white shrimp, Fenneropenaeus indicusMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2008S. Santhoshi Abstract Serotonin is one of the important neurotransmitter and neuromodulator so far studied in crustacean models. With its secretory sites well-studied in higher crustaceans, its function in controlling the release of metabolic hormones from their storage and release sites has been well proved. The present study attempts to localize serotonin-like immunoreactivity in Fenneropenaeus indicus, a commercially important shrimp species and a natural inhabitant of the Indian oceans. Histological studies were employed to visualize the different types of neurosecretory cells and their regions of occurrence in brain and optic ganglia on the basis of their size, shape, and tinctorial properties. Immunocytochemical studies were performed in the brain and optic ganglia with specific antisera against serotonin in combination with peroxidase anti-peroxidase to map the serotonin-like immunoreactive cells. Variations in the immunoreactivity were observed on comparing the cells of brain and optic ganglia. Medulla terminalis region had intense serotonin immunoreactivity suggesting it to be the primary source of the neurotransmitter. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source] Anatomy and functions of brain neurosecretory cells in dipteraMICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2003Sakiko Siga Abstract In the larval brain of dipteran insects, there are two medial and three lateral groups of neurons innervating the ring gland. One lateral group extends fibers to the corpus allatum. After metamorphosis, a large cluster of the medial group in the pars intercerebralis and two lateral groups in the pars lateralis innervate the retrocerebral complex and some neurons from the lateral group and a few from the medial group extend fibers to the corpus allatum in the adults. Neuropeptides such as insulin-like peptides, FMRFamide related peptides, Locusta -diuretic hormone, ,-pigment dispersing hormone, Manduca sexta -allatostatin, ovary ecdysteroidogenic hormone, and proctolin have been immunocytochemically revealed in medial groups in the pars intercerebralis, and FMRFamide related peptides, ,-pigment dispersing hormone, corazonin, and M. sexta -allatostatin in lateral groups in the pars lateralis of dipteran brains. In mosquitoes after the blood meal, ovary ecdysteroidogenic hormone from 2,3 pairs of medial neurosecretory cells is released at the corpus cardiacum to stimulate the ovaries to secrete ecdysteroid to cause ovarian development. In addition to ovarian development, removal and implantation experiments have shown that neurosecretory cells in the pars intercerebralis and pars lateralis are involved in control of reproductive diapause, cuticular tanning, sugar metabolism, and diures. Microsc. Res. Tech. 62:114,131, 2003. © 2003 Wiley-Liss, Inc. [source] The pars intercerebralis of the locust brain: A developmental and comparative studyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002Peter Ludwig Abstract The anterior midline of the brain, also known as the pars intercerebralis, contains the largest collection of neurosecretory cells in the central nervous system of the grasshopper. In this study, we use immunocytochemical, intracellular staining, and histological methods to establish the ontogenies of the various cell types in the brain midline, and show how these cells contribute to the pars intercerebralis of the adult brain. We show that the adult pars intercerebralis develops from three distinct embryonic cell groups: (1) the median neurosecretory cells, which derive from a subset of neuroblasts in the protocerebral hemispheres, and which project axons to the corpora cardiaca; (2) the paired primary commissure pioneers, which derive directly from the mesectoderm of the dorsal median domain and whose axons project to the ventral nerve cord via the midline tract; and (3) the six progeny of the median precursor in the dorsal median domain, which share a common axonal projection with the primary commissure pioneers. Since the adult pars intercerebralis is a fusion product of these independent cellular components, it can only be understood in terms of its origins in the embryonic brain. When the expression pattern of the TERM-1 antigen is compared in subsets of median neurosecretory cells in a wide range of insect orders, the results suggests a common organizational Bauplan for the pars intercerebralis. This hypothesis is supported by the identification of putative homologs of the grasshopper primary commissure pioneers in all these insects. Microsc. Res. Tech. 56:174,188, 2002. © 2002 Wiley-Liss, Inc. [source] Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetidaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2009Zsófia Herbert Abstract Periviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR( L/I)amide, SPLPR( L/I)amide, SFVR( L/I)amide, AFVR( L/I)amide, and SPAFVR( L/I)amide, were identified in the central nervous system with the common-XR( L/I)amide C-terminal sequence. The exact anatomical position of 13 labeled XR( I/L)amide expressing neuron groups and numerous peptide-containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole-mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine-fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister-groups of animals such as annelids, mollusks, and insects. J. Comp. Neurol. 514:415,432, 2009. © 2009 Wiley-Liss, Inc. [source] Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetidaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2009Zsófia Herbert Abstract Periviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR(L/I)amide, SPLPR(L/I)amide, SFVR(L/I)amide, AFVR(L/I)amide, and SPAFVR(L/I)amide, were identified in the central nervous system with the common ,XR(L/I)amide C-terminal sequence. The exact anatomical position of 13 labeled XR(I/L)amide expressing neuron groups and numerous peptide-containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole-mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine-fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister-groups of animals such as annelids, mollusks, and insects. J. Comp. Neurol. 514:415,432, 2009. © 2009 Wiley-Liss, Inc. [source] Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetidaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2009Zsófia Herbert Abstract Periviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR(L/I)amide, SPLPR(L/I)amide, SFVR(L/I)amide, AFVR(L/I)amide, and SPAFVR(L/I)amide, were identified in the central nervous system with the common ,XR(L/I)amide C-terminal sequence. The exact anatomical position of 13 labeled XR(I/L)amide expressing neuron groups and numerous peptide-containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole-mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine-fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister-groups of animals such as annelids, mollusks, and insects. J. Comp. Neurol. 514:415,432, 2009. © 2009 Wiley-Liss, Inc. [source] Flufenamic acid blocks depolarizing afterpotentials and phasic firing in rat supraoptic neuronesTHE JOURNAL OF PHYSIOLOGY, Issue 2 2002Masoud Ghamari-Langroudi Depolarizing afterpotentials (DAPs) that follow action potentials in magnocellular neurosecretory cells (MNCs) are thought to underlie the generation of phasic firing, a pattern that optimizes vasopressin release from the neurohypophysis. Previous work has suggested that the DAP may result from the Ca2+ -dependent reduction of a resting K+ conductance. Here we examined the effects of flufenamic acid (FFA), a blocker of Ca2+ -dependent non-selective cation (CAN) channels, on DAPs and phasic firing using intracellular recordings from supraoptic MNCs in superfused explants of rat hypothalamus. Application of FFA, but not solvent (0.1 % DMSO), reversibly inhibited (IC50+ 13.8 ,m; R+ 0.97) DAPs and phasic firing with a similar time course, but had no significant effects (P > 0.05) on membrane potential, spike threshold and input resistance, nor on the frequency and amplitude of spontaneous synaptic potentials. Moreover, FFA did not affect (P > 0.05) the amplitude, duration, undershoot, or frequency-dependent broadening of action potentials elicited during the spike trains used to evoke DAPs. These findings suggest that FFA inhibits the DAP by directly blocking the channels responsible for its production, rather than by interfering with Ca2+ influx. They also support a role for DAPs in the generation of phasic firing in MNCs. Finally, the absence of a depolarization and increased membrane resistance upon application of FFA suggests that the DAP in MNCs may not be due to the inhibition of resting K+ current, but to the activation of CAN channels. [source] | |||||||||||||