1
|
Lim D, Semyanov A, Genazzani A, Verkhratsky A. Calcium signaling in neuroglia. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:1-53. [PMID: 34253292 DOI: 10.1016/bs.ircmb.2021.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glial cells exploit calcium (Ca2+) signals to perceive the information about the activity of the nervous tissue and the tissue environment to translate this information into an array of homeostatic, signaling and defensive reactions. Astrocytes, the best studied glial cells, use several Ca2+ signaling generation pathways that include Ca2+ entry through plasma membrane, release from endoplasmic reticulum (ER) and from mitochondria. Activation of metabotropic receptors on the plasma membrane of glial cells is coupled to an enzymatic cascade in which a second messenger, InsP3 is generated thus activating intracellular Ca2+ release channels in the ER endomembrane. Astrocytes also possess store-operated Ca2+ entry and express several ligand-gated Ca2+ channels. In vivo astrocytes generate heterogeneous Ca2+ signals, which are short and frequent in distal processes, but large and relatively rare in soma. In response to neuronal activity intracellular and inter-cellular astrocytic Ca2+ waves can be produced. Astrocytic Ca2+ signals are involved in secretion, they regulate ion transport across cell membranes, and are contributing to cell morphological plasticity. Therefore, astrocytic Ca2+ signals are linked to fundamental functions of the central nervous system ranging from synaptic transmission to behavior. In oligodendrocytes, Ca2+ signals are generated by plasmalemmal Ca2+ influx, or by release from intracellular stores, or by combination of both. Microglial cells exploit Ca2+ permeable ionotropic purinergic receptors and transient receptor potential channels as well as ER Ca2+ release. In this contribution, basic morphology of glial cells, glial Ca2+ signaling toolkit, intracellular Ca2+ signals and Ca2+-regulated functions are discussed with focus on astrocytes.
Collapse
Affiliation(s)
- Dmitry Lim
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy.
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia; Faculty of Biology, Moscow State University, Moscow, Russia; Sechenov First Moscow State Medical University, Moscow, Russia
| | - Armando Genazzani
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy
| | - Alexei Verkhratsky
- Sechenov First Moscow State Medical University, Moscow, Russia; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| |
Collapse
|
2
|
Young JK. Neurogenesis Makes a Crucial Contribution to the Neuropathology of Alzheimer's Disease. J Alzheimers Dis Rep 2020; 4:365-371. [PMID: 33163897 PMCID: PMC7592839 DOI: 10.3233/adr-200218] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
One unexplained feature of Alzheimer’s disease (AD) is that the lateral entorhinal cortex undergoes neurodegeneration before other brain areas. However, this brain region does not have elevated levels of amyloid peptides in comparison with undamaged regions. What is the cause of this special vulnerability of the entorhinal cortex? One special feature of the lateral entorhinal cortex is that it projects to newborn neurons that have undergone adult neurogenesis in the dentate gyrus of the hippocampus. Neurogenesis is abnormal in human AD brains, and modulation of neurogenesis in experimental animals influences the course of AD. This complex process of neurogenesis may expose axon terminals originating from neurons of the entorhinal cortex to a unique combination of molecules that can enhance toxic effects of amyloid. Retrograde degeneration of neurons with axons terminating in the dentate gyrus provides a likely explanation for the spatial patterns of neuronal cell death seen in AD. Specialized astrocytes in the dentate gyrus participate in adult neurogenesis and produce fatty acid binding protein7 (FABP7). These FABP7+ cells undergo an aging-related mitochondrial pathology that likely impairs their functions. This age-related abnormality may contribute to the impairment in neurogenesis seen in aging and Alzheimer’s disease. Also, a compromised function of these astrocytes likely results in local elevations of palmitic acid, iron, copper, and glucose, which all enhance the toxicity of amyloid peptides. Treatments that modulate neurogenesis or diminish the production of these toxic substances may prove more successful than treatments that are solely aimed at reducing the amyloid burden alone.
Collapse
Affiliation(s)
- John K Young
- Professor Emeritus, Department of Anatomy, Howard University College of Medicine, Washington, DC, USA
| |
Collapse
|
3
|
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| |
Collapse
|
4
|
Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 928] [Impact Index Per Article: 154.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| |
Collapse
|
5
|
Sullivan B, Robison G, Pushkar Y, Young JK, Manaye KF. Copper accumulation in rodent brain astrocytes: A species difference. J Trace Elem Med Biol 2017; 39:6-13. [PMID: 27908425 PMCID: PMC5141684 DOI: 10.1016/j.jtemb.2016.06.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/23/2016] [Accepted: 06/30/2016] [Indexed: 12/15/2022]
Abstract
Changes in Cu homeostasis have been implicated in multiple neurodegenerative diseases. Factors controlling and regulating the distribution of Cu in the brain remain largely unknown. We have previously reported that a sub-set of astrocytes in the subventricular zone (SVZ) contain Cu-rich aggregates. Here we expand previous studies with detailed X-ray fluorescent imaging (XRF) analysis of the additional brain areas of hippocampus (HP) and rostral migratory stream (RMS). We also use conventional DAB (3,3'-diaminobenzidine) staining which accesses both peroxidase and pseudo-peroxidase activities. Both the HP and RMS support neurogenesis while the latter also serves as a migratory pathway for neuronal precursors. Some variations in neurogenic activities have been noticed between species (such as mice and rats). We report here that in rats, the HP, rostral migratory stream (RMS) and third ventricle contain glia which stain positively for DAB and contain copper-rich aggregates as measured by XRF. In contrast, mice hippocampi and RMS display neither DAB+ aggregates nor Cu-rich accumulations via XRF. DAB+ aggregates were not induced in the HP of mice transgenic for human amyloid precursor protein (APP) and presenilin, suggesting that accumulations positively stained for DAB are not directly caused by APP. These observed critical differences suggest different properties of the astrocytes in two species. Results suggest that the rat model may have important advantages over the mouse model for the study of hippocampal aging and neurodegeneration.
Collapse
Affiliation(s)
- Brendan Sullivan
- Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave., West Lafayette, IN 47907, United States
| | - Gregory Robison
- Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave., West Lafayette, IN 47907, United States; Department of Physics, Hanover College, Hanover, IN, United States
| | - Yulia Pushkar
- Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave., West Lafayette, IN 47907, United States.
| | - John K Young
- Department of Anatomy, Howard University College of Medicine 520 W St., NW, Washington DC 20059, United States
| | - Kebreten F Manaye
- Department of Physiology, Howard University College of Medicine 520 W St., NW, Washington DC 20059, United States
| |
Collapse
|
6
|
Young JK, McKenzie JC. GLUT2 immunoreactivity in Gomori-positive astrocytes of the hypothalamus. J Histochem Cytochem 2004; 52:1519-24. [PMID: 15505347 PMCID: PMC3957823 DOI: 10.1369/jhc.4a6375.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A specialized subtype of astrocyte, the Gomori-positive (GP) astrocyte, is unusually abundant and prominent in the arcuate nucleus of the hypothalamus. GP astrocytes possess cytoplasmic granules derived from degenerating mitochondria. GP granules are highly stained by Gomori's chrome alum hematoxylin stain, by the Perl's reaction for iron, or by toluidine blue. The source of the oxidative stress causing mitochondrial damage in GP astrocytes is uncertain, but such damage could arise from the oxidative metabolism of glucose transported into astrocytes by high-capacity GLUT2 glucose transporters. In accord with this hypothesis, the reported anatomical distribution of astrocytes staining positively for GLUT2 glucose transporters closely matches that of GP astrocytes. To examine whether or not these two staining procedures detect the same population of astrocytes, immunocytochemistry was performed on semithin sections to detect GLUT2 protein and sections were then stained with toluidine blue to detect GP granules. It was determined that GP astrocytes are frequently immunoreactive for the GLUT2 transporter protein. These data support the possibility that GP astrocytes may have an important influence upon the reactivity of the hypothalamus to glucose and that a specialized glucose metabolism may in part underlie the development of mitochondrial abnormalities in hypothalamic GP astrocytes.
Collapse
Affiliation(s)
- John K Young
- Department of Anatomy, Howard University College of Medicine, 520 W Street, N.W., Washington, DC 20059, USA.
| | | |
Collapse
|
7
|
Abstract
Two brain regions - the basomedial hypothalamus and area postrema (AP) - react to changes in circulating glucose levels by altering feeding behavior and the secretion of pituitary and non-pituitary hormones. The precise identity of cells responding to glucose in these regions is uncertain. The recent detection of high-capacity glucose transporter proteins in astrocytes in these areas has suggested that astrocytes may play a role in glucose sensing by the brain. To test this hypothesis, rats were injected with either saline or methionine sulfoximine (MS), a compound that produces alterations in carbohydrate and glutamate metabolism in astrocytes. Eighteen hours later, rats were injected with either saline or 2-deoxy glucose (2-DG) and brain sections were stained to demonstrate 2-DG-activated neurons immunoreactive for Fos protein. MS-treated rats showed a 70% reduction in numbers of Fos+ neurons in the AP region (p<0.05). Also, specialized, Gomori+ astrocytes were particularly abundant in both glucose sensitive regions and showed a distribution identical to that reported for high-capacity glucose transporter proteins. These data suggest that specialized astrocytes influence the glucose-sensing function of the brain.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy, Howard University College of Medicine, 520 W. Street NW, Washington DC 20059, USA.
| | | | | |
Collapse
|
8
|
Ross JF, Switzer RC, Poston MR, Lawhorn GT. Distribution of bismuth in the brain after intraperitoneal dosing of bismuth subnitrate in mice: implications for routes of entry of xenobiotic metals into the brain. Brain Res 1996; 725:137-54. [PMID: 8836520 DOI: 10.1016/0006-8993(96)00146-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Bismuth (Bi) can produce neurotoxic effects in both humans and animals under certain dosing conditions, but little else is known about the effects of Bi in the brain. In the present study we determined the distribution of Bi in the brains of adult female Swiss-Webster mice 4, 7, 14, 21 and 28 days after a single 2500 mg/kg i.p. injection of Bi subnitrate (BSN), which establishes a depot of absorbable Bi and produces morphological signs of neurotoxicity. Sections of brains were processed by autometallographic (AMG) procedures that produced silver grains at the site of Bi localization (AMGBi). Ventricular dilation was observed in all BSN-dosed mice. Among treated mice there were marked interanimal differences in the absolute amount of AMGBi, but consistent regional and cellular patterns of AMGBi were observed. AMGBi was observed in many cell types in brain regions adjacent to fenestrated blood vessels of the circumventricular organs (CVOs) and olfactory epithelium. Prominent intrasomal AMGBi was observed in nuclei containing large cell bodies, including cranial motor neurons innervating somatic muscle, lateral vestibular and red nucleus and pontine/medullary reticular nuclei. In the hypothalamus, the supraoptic and paraventricular nuclei demonstrated the densest AMGBi. In the cerebellum, Purkinje and granule cell layers with the densest AMGBi were in folia adjacent to the fourth ventricle. In the hippocampus, AMGBi was densest in the fasciola cinerum, polymorph cells of the dentate gyrus, and pyramidal cell layer of the CA3 regions. Neuropil of subcortical auditory nuclei (cochlear nucleus, trapezoid body, lateral lemniscus and nucleus of lateral lemniscus, medial geniculate nucleus and inferior colliculus) had a high density of AMGBi. Among nonneuronal cells, ependyma and meninges lining the ventricular and subarachnoid spaces were labeled extensively. Glial labeling was prominent adjacent to CVOs, in subependymal regions, and in fiber tracts. Presumptive perivascular cells lining large blood vessels had extremely dense AMGBi as early as 4 days after dosing. Smaller blood vessels had moderate AMGBi. However, in regions (e.g. cerebral cortex, striatum) known to have low brain Bi levels after i.p. dosing, vascular deposits accounted for most of the AMGBi. Several animals had foci of AMGBi which suggested that vascular or perivascular aberrations may have contributed to the unusually dense accumulations. The results of the present studies indicate that Bi accumulates predictably in certain regions and cell types. The pattern of regions and cells with the highest AMGBi accumulations is very similar to pattern reported for other xenobiotic metals (i.e. mercury, silver, gold), and supports the hypothesis that these metals may share some mechanisms for entry, distribution and storage in the brain.
Collapse
Affiliation(s)
- J F Ross
- Procter and Gamble Company, Miami Valley Laboratories, Cincinnati, OH 45239-8707, USA
| | | | | | | |
Collapse
|
9
|
Abstract
Gomori-positive (GP) astrocytes are a subset of brain astrocytes with highly stained cytoplasmic granules that arise from the degradation of mitochondria. The GP granules of these astrocytes are most prominent in the arcuate nucleus of the hypothalamus, but can also be detected in the olfactory bulbs, hippocampus, habenula, and other selected brain regions. The cause and functional effects of this mitochondrial pathology in these glia are not yet known with certainty. In other tissues, mitochondrial dysfunction is associated with elevations in cytoplasmic lipids and lipid-binding proteins, due to impaired mitochondrial oxidation of lipids. To see if GP astrocytic mitochondrial pathology is also associated with an elevation in lipid binding proteins, rat brain sections were stained for brain fatty acid binding protein (B-FABP), using immunocytochemistry. Astrocytes immunoreactive for B-FABP were much more abundant in brain regions enriched in GP astrocytes than in other brain regions. Semi-thin sections revealed that astrocytic B-FABP immunoreactivity was often, but not always, associated with GP cytoplasmic granules. These data suggest that GP astrocytes have an unusual lipid metabolism, which may relate to degenerative processes occurring in the selected brain regions that contain GP astrocytes.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy, Howard University, Washington DC 20059, USA
| | | | | |
Collapse
|
10
|
A Progressive Ballooning of Myelinated, TH-Positive Axons is Produced by MPTP in the Dog. NEURODEGENER DIS 1996. [DOI: 10.1007/978-1-4899-0209-2_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
11
|
Dickinson TK, Connor JR. Cellular distribution of iron, transferrin, and ferritin in the hypotransferrinemic (Hp) mouse brain. J Comp Neurol 1995; 355:67-80. [PMID: 7636015 DOI: 10.1002/cne.903550109] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Hypotransferrinemic (Hp) mice have a point mutation or small deletion in the transferrin (Tf) gene, resulting in defective splicing of precursor Tf mRNA. Hp animals produce < 1% of normal Tf levels and require supplemental serum or purified Tf for survival. Because of the lack of endogenous brain Tf, we examined regional and cellular distributions of iron and iron regulatory proteins (Tf and ferritin) in selected brain regions of Hp mice. The regional distribution of iron, Tf, and ferritin in Hp brain was similar to normal except for the pattern of iron staining in hippocampus. The cellular distribution of iron, ferritin, and Tf was similar between Hp and normal animals. The predominant cell type staining for Tf and iron was oligodendrocytes. Qualitative observations suggest that the number of cells staining for iron was similar between Hp and normal mice, whereas the number of Hp Tf-positive cells was reduced. Ferritin immunostaining was similar in both cases. However, ferritin-positive cells were predominantly astrocytes, an observation unique to mice among species studied previously. Western blot analysis revealed that Tf present in Hp brain was of exogenous origin (from supplemental injections). Presumably, Tf transports the iron found in Hp oligodendrocytes. These data demonstrate that, despite reduced endogenous Hp brain Tf, iron and plasma Tf migrate or are transported to the appropriate cells (oligodendrocytes), bringing into question the role of endogenous brain Tf in extracellular iron transport.
Collapse
Affiliation(s)
- T K Dickinson
- George M. Leader Family Laboratory For Alzheimer's Disease Research, Department of Neuroscience and Anatomy, Pennsylvania State University, College of Medicine, M.S. Hershey Medical Center, Hershey 17033, USA
| | | |
Collapse
|
12
|
Young JK. Immunoreactivity for diazepam binding inhibitor in Gomori-positive astrocytes. REGULATORY PEPTIDES 1994; 50:159-65. [PMID: 7514799 DOI: 10.1016/0167-0115(94)90031-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A polypeptide termed diazepam binding inhibitor (DBI), capable of binding to receptor sites on glial mitochondria, is known to be present in glial cells and is particularly abundant in areas near circumventricular organs of the brain such as the arcuate nucleus of the hypothalamus. DBI appears to stimulate steroid synthesis and/or transport in glial mitochondria. The arcuate nucleus also contains large numbers of specialized glia, termed Gomori-positive astrocytes, that are estrogen-sensitive and which possess highly stained, heme-containing cytoplasmic granules. This study was performed to determine if these Gomori-positive astrocytes are immunoreactive for DBI. A rabbit antibody to DBI, but not pre-immune serum, stained Gomori-positive glia and suggests that these glia are partly responsible for the high levels of DBI in circumventricular organs. DBI in these glia may be related to functional responses of the hypothalamus to steroid hormones.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy College of Medicine, Howard University, Washington, DC 20059
| |
Collapse
|
13
|
Young JK, McKenzie JC, Brady LS, Herkenham M. Hypothalamic lesions increase levels of neuropeptide Y mRNA in the arcuate nucleus of mice. Neurosci Lett 1994; 165:13-7. [PMID: 8015714 DOI: 10.1016/0304-3940(94)90698-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A recent study demonstrated that hypothalamic lesions induced by goldthioglucose (GTG) in mice produced an increase in neuronal immunoreactivity for neuropeptide Y (NPY) in the hypothalamic arcuate nucleus. Since NPY is a potent stimulator of feeding, this increase represented a potential explanation for the hyperphagia seen after GTG lesions. To examine whether or not this increase in NPY immunoreactivity was accompanied by an increase in the mRNA for NPY, in situ hybridization histochemistry for NPY mRNA in control and in lesioned mice was performed. A 47% increase in NPY mRNA levels in the arcuate nucleus was observed in lesioned mice compared with controls, suggesting that an increased expression of the gene for NPY contributes to elevations in hypothalamic NPY after lesioning. This elevation in NPY may, in turn, relate to mechanisms provoking hyperphagia.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy, Howard University, Washington, DC 20059
| | | | | | | |
Collapse
|
14
|
Pickel VM, Chan J, Sesack SR. Cellular substrates for interactions between dynorphin terminals and dopamine dendrites in rat ventral tegmental area and substantia nigra. Brain Res 1993; 602:275-89. [PMID: 8095430 DOI: 10.1016/0006-8993(93)90693-h] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dynorphin and other kappa opioid agonists are thought to elicit aversive actions and changes in motor activity through direct or indirect modulation of dopamine neurons in ventral tegmental area (VTA) and substantia nigra (SN), respectively. We comparatively examined the immunoperoxidase localization of anti-dynorphin A antiserum in sections through the VTA and SN of adult rat brain to assess whether there were common or differential distributions of this opioid peptide relative to the dopamine neurons. We also more directly examined the relationship between dynorphin terminals and dopamine neurons in VTA and SN by combining immunoperoxidase labeling of rabbit dynorphin antiserum and immunogold-silver detection of mouse antibodies against tyrosine hydroxylase (TH) in single sections through the VTA and SN. Light microscopy showed dynorphin-like immunoreactivity (DY-LI) in varicose processes. These were relatively sparse in VTA and were unevenly distributed in the SN, with little labeling in the pars compacta (pcSN) and the highest density of DY-LI in the medial and lateral pars reticulata (prSN). Electron microscopy established that the regional differences were attributed to differences in density (number/unit area) of immunoreactive profiles. The profiles containing DY-LI were designated as axon terminals based on having diameters greater than 0.1 micron, few microtubules and many synaptic vesicles. In both the VTA and SN, the dynorphin-labeled terminals contained primarily small (35-40 nm) clear vesicles. These vesicles were rimmed with peroxidase immunoreactivity and were often seen clustered above axodendritic synapses. These synaptic specializations were usually symmetric; however a few asymmetric densities also were formed by immunoreactive terminals in both VTA and SN. Additionally, most of the dynorphin-labeled terminals contained 1-2, but occasionally 7 or more intensely peroxidase positive dense core vesicles (DCVs). Approximately 60% of the DCVs were located near axolemmal surfaces. The axolemmal surfaces contacted by immunoreactive DCVs were more often apposed to dendrites in the VTA; while in the SN other axon terminals were the most commonly apposed neuronal profiles. In both regions, a substantial proportion of the plasmalemmal surface in contact with the labeled DCVs was apposed to astrocytic processes.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- V M Pickel
- Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021
| | | | | |
Collapse
|
15
|
Abstract
An enhanced production of hypothalamic neuropeptide Y (NPY) now appears to underlie a number of hyperphagia syndromes. However, the role of NPY in the hyperphagia induced by hypothalamic lesions has not yet been explored. Here, hypothalamic lesions were induced in mice by administration of goldthioglucose (GTG) and brain sections were stained immunocytochemically for NPY without pretreatment with colchicine. NPY-immunoreactive somas were visible in the hypothalamus of only one of eight control mice but were identified in the hypothalami of six of seven mice with GTG lesions. This suggests that GTG lesions cause an enhanced production of NPY, perhaps due to interruption of fibers from arcuate dopaminergic neurons that normally inhibit NPY+ cells. Thus, hypothalamic lesions may provoke hyperphagia by stimulating the production of NPY.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy, Howard University, Washington, DC 20059
| |
Collapse
|
16
|
Abstract
Considerable evidence suggests that in Alzheimer's disease, olfactory bulb damage may be a primary factor, causing degeneration and neurofibrillary tangles primarily in neurons connected with this brain area. Also, deposits of amyloid may involve an improper regulation of the cleavage of a precursor protein by glia. Finally, toxic effects of aluminium may be an etiological factor. This review proposes that all these seemingly unrelated aspects of Alzheimer's disease could be related to a disturbed function of metal-containing glia. Such a disturbance, initiated by or aggravating toxic effects of aluminum, may underlie initial damage in the olfactory bulb and/or other brain areas with a weakened blood-brain barrier and may be responsible for amyloid deposition.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy, Howard University, Washington DC 20059
| |
Collapse
|
17
|
Schipper HM. Gomori-positive astrocytes: biological properties and implications for neurologic and neuroendocrine disorders. Glia 1991; 4:365-77. [PMID: 1718859 DOI: 10.1002/glia.440040404] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Granule laden astrocytes exhibiting an affinity for chrome alum hematoxylin and aldehyde fuchsin (Gomori stains) have been described in the periventricular brain of all terrestrial vertebrate species examined to date including humans. The astrocytic inclusions are rich in sulfhydryl groups, emit an orange-red autofluorescence, and stain intensely with diaminobenzidine, a marker of endogenous peroxidase activity. The distinct autofluorescence pattern and the absence of neutral lipid, acid phosphatase, and beta-glucuronidase activity exclude lipofuscin or lysosomes as components of these astrocytic granules. The emission of orange-red autofluorescence and the nonenzymatic nature of the peroxidase activity implicate the presence of porphyrins and metalloporphyrins such as heme as major constituents of these cytoplasmic gliosomes. The role of Gomori-positive astrocytes under normal and pathologic conditions is incompletely understood. In vivo, numbers of astrocytic granules increase as a function of advancing age, in response to chronic estrogen stimulation, and following X-irradiation. In vitro, these cells accumulate with increasing time in culture and following exposure to the sulfhydryl agent, cysteamine. Gomori-positive astrocytes may supply heme to neurons for the synthesis of cytochromes, catalases, and other heme enzymes. They may play a role in photostimulation of sexual cyclicity, the promotion of neuritic development, the degradation of toxic lipoperoxides, and the metabolism of various neurotransmitters. Conversely, these cells may contribute to the pathogenesis of several neurologic and neuroendocrine disorders. Examples of the latter include a) augmentation of goldthioglucose neurotoxicity, b) induction of hypothalamic anovulation and reproductive failure, c) exacerbation of porphyric encephalopathy, and d) potentiation of parkinsonism and other free radical-related neurodegenerations.
Collapse
Affiliation(s)
- H M Schipper
- Department of Neurology, McGill University, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| |
Collapse
|
18
|
Abstract
A series of frozen and vibratome coronal sections of the rat brain were examined by immunocytochemistry for the presence of a cysteine-rich metal binding protein, metallothionein (MT). Astrocytes throughout the brain and brainstem stained positively for MT; neurons and oligodendroglia were unstained. Ependymal cells and tanycyte processes in the hypothalamus were also immunoreactive, along with a narrow zone of immunopositivity along the margins of the area postrema. Gomori-positive astrocytes in the hypothalamus, identifiable by toluidine blue staining, metal-containing cytoplasmic granules, represented a subset of MT-positive astrocytes that may be involved in reactions to blood-borne metal compounds that penetrate into circumventricular organs of the brain.
Collapse
Affiliation(s)
- J K Young
- Department of Anatomy, Howard University, Washington, District of Columbia 20059
| | | | | |
Collapse
|