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Höflich KM, Beyer C, Clarner T, Schmitz C, Nyamoya S, Kipp M, Hochstrasser T. Acute axonal damage in three different murine models of multiple sclerosis: A comparative approach. Brain Res 2016; 1650:125-133. [PMID: 27592741 DOI: 10.1016/j.brainres.2016.08.048] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/30/2016] [Accepted: 08/31/2016] [Indexed: 01/12/2023]
Abstract
Axonal damage has been identified as a significant contributor to permanent clinical disability in multiple sclerosis. In the context of demyelinating disorders, this destructive event can be the result of inflammation, demyelination and/or the activation of innate defense cells such as microglia or monocytes. The relative contribution of each of these variables to acute axonal injury is, however, unknown. In the present study, we compared the extent of acute axonal damage in three different murine demyelination models using anti-amyloid precursor protein (APP) immunohistochemistry. T cell dependent (MOG35-55-induced experimental autoimmune encephalomyelitis (EAE)) as well as T cell independent demyelination models (cuprizone- and lysolecithin-induced demyelination) were used. APP+ spheroids were present in all three experimental demyelination models. The number of APP+ spheroids was highest within LPC-induced lesions. Equal amounts were found in the spinal cord of MOG35-55-EAE animals and the corpus callosum of cuprizone-intoxicated animals. Moreover, we detected increased immunoreactivity of the pre-synaptic protein vesicular glutamate transporter 1 (VGluT1) in demyelinated foci. VGluT1-staining revealed long stretched, ovoid-like axonal structures which co-localized with APP. In summary, we showed that acute axonal damage is evident under various experimental demyelination paradigms. Furthermore, disturbed axonal transport mechanisms, which are responsible for intra-axonal APP accumulation, do not only disturb APP, but also the transport of other synaptic proteins. These results indicate that, despite differences in their characteristics, all three models may serve as valid and suitable systems for investigating responsible mechanisms of axonal damage and potential protective strategies.
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Affiliation(s)
- Katharina Marie Höflich
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany
| | - Cordian Beyer
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany
| | - Tim Clarner
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany
| | - Christoph Schmitz
- Department of Neuroanatomy, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany
| | - Stella Nyamoya
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany; Department of Neuroanatomy, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany
| | - Markus Kipp
- Department of Neuroanatomy, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany
| | - Tanja Hochstrasser
- Department of Neuroanatomy, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany.
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Yin W, Sun Z, Mendenhall JM, Walker DM, Riha PD, Bezner KS, Gore AC. Expression of Vesicular Glutamate Transporter 2 (vGluT2) on Large Dense-Core Vesicles within GnRH Neuroterminals of Aging Female Rats. PLoS One 2015; 10:e0129633. [PMID: 26053743 PMCID: PMC4459826 DOI: 10.1371/journal.pone.0129633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/10/2015] [Indexed: 11/20/2022] Open
Abstract
The pulsatile release of GnRH is crucial for normal reproductive physiology across the life cycle, a process that is regulated by hypothalamic neurotransmitters. GnRH terminals co-express the vesicular glutamate transporter 2 (vGluT2) as a marker of a glutamatergic phenotype. The current study sought to elucidate the relationship between glutamate and GnRH nerve terminals in the median eminence—the site of GnRH release into the portal capillary vasculature. We also determined whether this co-expression may change during reproductive senescence, and if steroid hormones, which affect responsiveness of GnRH neurons to glutamate, may alter the co-expression pattern. Female Sprague-Dawley rats were ovariectomized at young adult, middle-aged and old ages (~4, 11, and 22 months, respectively) and treated four weeks later with sequential vehicle + vehicle (VEH + VEH), estradiol + vehicle (E2 + VEH), or estradiol + progesterone (E2+P4). Rats were perfused 24 hours after the second hormone treatment. Confocal microscopy was used to determine colocalization of GnRH and vGluT2 immunofluorescence in the median eminence. Post-embedding immunogold labeling of GnRH and vGluT2, and a serial electron microscopy (EM) technique were used to determine the cellular interaction between GnRH terminals and glutamate signaling. Confocal analysis showed that GnRH and vGluT2 immunofluorescent puncta were extensively colocalized in the median eminence and that their density declined with age but was unaffected by short-term hormone treatment. EM results showed that vGluT2 immunoreactivity was extensively associated with large dense-core vesicles, suggesting a unique glutamatergic signaling pathway in GnRH terminals. Our results provide novel subcellular information about the intimate relationship between GnRH terminals and glutamate in the median eminence.
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Affiliation(s)
- Weiling Yin
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Zengrong Sun
- School of Public Health, Tianjin Medical University, Tianjin, China
| | - John M. Mendenhall
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas, United States of America
| | - Deena M. Walker
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas, United States of America
| | - Penny D. Riha
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Kelsey S. Bezner
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Andrea C. Gore
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas, United States of America
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Lomniczi A, Wright H, Castellano JM, Sonmez K, Ojeda SR. A system biology approach to identify regulatory pathways underlying the neuroendocrine control of female puberty in rats and nonhuman primates. Horm Behav 2013; 64:175-86. [PMID: 23998662 PMCID: PMC3933372 DOI: 10.1016/j.yhbeh.2012.09.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/31/2012] [Accepted: 09/23/2012] [Indexed: 01/06/2023]
Abstract
This article is part of a Special Issue "Puberty and Adolescence". Puberty is a major developmental milestone controlled by the interaction of genetic factors and environmental cues of mostly metabolic and circadian nature. An increased pulsatile release of the decapeptide gonadotropin releasing hormone (GnRH) from hypothalamic neurosecretory neurons is required for both the initiation and progression of the pubertal process. This increase is brought about by coordinated changes that occur in neuronal and glial networks associated with GnRH neurons. These changes ultimately result in increased neuronal and glial stimulatory inputs to the GnRH neuronal network and a reduction of transsynaptic inhibitory influences. While some of the major players controlling pubertal GnRH secretion have been identified using gene-centric approaches, much less is known about the system-wide control of the overall process. Because the pubertal activation of GnRH release involves a diversity of cellular phenotypes, and a myriad of intracellular and cell-to-cell signaling molecules, it appears that the overall process is controlled by a highly coordinated and interactive regulatory system involving hundreds, if not thousands, of gene products. In this article we will discuss emerging evidence suggesting that these genes are arranged as functionally connected networks organized, both internally and across sub-networks, in a hierarchical fashion. According to this concept, the core of these networks is composed of transcriptional regulators that, by directing expression of downstream subordinate genes, provide both stability and coordination to the cellular networks involved in initiating the pubertal process. The integrative response of these gene networks to external inputs is postulated to be coordinated by epigenetic mechanisms.
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Affiliation(s)
- Alejandro Lomniczi
- Division of Neuroscience, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR 97006, USA.
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Sinnamon JR, Waddell CB, Nik S, Chen EI, Czaplinski K. Hnrpab regulates neural development and neuron cell survival after glutamate stimulation. RNA (NEW YORK, N.Y.) 2012; 18:704-19. [PMID: 22332140 PMCID: PMC3312558 DOI: 10.1261/rna.030742.111] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The molecular mechanisms that govern the timing and fate of neural stem-cell differentiation toward the distinct neural lineages of the nervous system are not well defined. The contribution of post-transcriptional regulation of gene expression to neural stem-cell maintenance and differentiation, in particular, remains inadequately characterized. The RNA-binding protein Hnrpab is highly expressed in developing nervous tissue and in neurogenic regions of the adult brain, but its role in neural development and function is unknown. We raised a mouse that lacks Hnrpab expression to define what role, if any, Hnrpab plays during mouse neural development. We performed a genome-wide quantitative analysis of protein expression within the hippocampus of newborn mice to demonstrate significantly altered gene expression in mice lacking Hnrpab relative to Hnrpab-expressing littermates. The proteins affected suggested an altered pattern of neural development and also unexpectedly indicated altered glutamate signaling. We demonstrate that Hnrpab(-/-) neural stem and progenitor cells undergo altered differentiation patterns in culture, and mature Hnrpab(-/-) neurons demonstrate increased sensitivity to glutamate-induced excitotoxicity. We also demonstrate that Hnrpab nucleocytoplasmic distribution in primary neurons is regulated by developmental stage.
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Affiliation(s)
- John R. Sinnamon
- Program in Neuroscience, Stony Brook University, Stony Brook, New York 11794, USA
- Center for Nervous Systems Disorders, Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11794, USA
| | - Catherine B. Waddell
- Center for Nervous Systems Disorders, Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11794, USA
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, USA
| | - Sara Nik
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, USA
| | - Emily I. Chen
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, USA
- Stony Brook University Proteomics Center, Stony Brook University, Stony Brook, New York 11794, USA
| | - Kevin Czaplinski
- Center for Nervous Systems Disorders, Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11794, USA
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, USA
- Corresponding author.E-mail .
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Elias CF. Leptin action in pubertal development: recent advances and unanswered questions. Trends Endocrinol Metab 2012; 23:9-15. [PMID: 21978495 PMCID: PMC3251729 DOI: 10.1016/j.tem.2011.09.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 09/01/2011] [Accepted: 09/08/2011] [Indexed: 11/18/2022]
Abstract
In recent years we have witnessed a considerable advance in the understanding of the processes involved in pubertal development. This is partially due to the discovery of the kisspeptin system and its fundamental role in the control of reproductive physiology. In addition, the suspected relationship between increasing rates of childhood obesity and the apparent reduction in the age of puberty onset in girls has generated a growing interest in identifying the mechanisms by which nutrition may influence reproductive maturation. This review will focus on recent data unveiling the sites of leptin action in pubertal development that were generated using novel molecular techniques and genetically engineered mouse models. It will also emphasize areas of contention and the many relevant questions that remain unanswered.
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Affiliation(s)
- Carol F Elias
- Department of Internal Medicine, Division of Hypothalamic Research and Green Center for Reproductive Biology Sciences, University of Texas Southwestern (UTSW) Medical Center, Dallas, TX 75390, USA.
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Meza-Herrera CA, Torres-Moreno M, López-Medrano JI, González-Bulnes A, Veliz FG, Mellado M, Wurzinger M, Soto-Sanchez MJ, Calderón-Leyva MG. Glutamate supply positively affects serum release of triiodothyronine and insulin across time without increases of glucose during the onset of puberty in female goats. Anim Reprod Sci 2011; 125:74-80. [PMID: 21530114 DOI: 10.1016/j.anireprosci.2011.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/17/2011] [Accepted: 03/28/2011] [Indexed: 11/17/2022]
Abstract
The current study evaluated the effect of glutamate supply on the onset of puberty and possible links to changes in serum concentrations of insulin [INS], glucose [GLU] and triiodothyronine [T(3)]. The study was conducted from June to November in prepuberal female goats (n=18; 3 mo. old, 7/8 Saanen-Alpine, 1/8 Criollo, 26° north) randomly assigned to two experimental groups: (i) excitatory amino acids group (group AA, n=10; 16.52±1.04 kg LW, 3.4±0.12 body condition score [BCS], receiving an intravenous infusion of 7 mg kg(-1) live weight [LW] of l-glutamate, twice a week, and (ii) control group (group CC, n=8; 16.1±1.04 kg LW, 3.1±0.12 BCS) receiving saline. Blood samples were obtained twice a week, for assessing progesterone [P(4)], as well as in a monthly basis to evaluate INS and T(3) by RIA. Mean final LW and BCS were 23.2±0.72 kg, 3.53±0.10 units, without differences between groups. The AA group depicted an earlier onset of puberty (6.9±0.3 compared to 7.5±0.4 mo.; P<0.05) and an increased ovarian activity (70±0.28% compared to 25±0.26%; P<0.05). Neither serum INS concentrations nor serum glucose concentrations differed between treatments (1.2±0.06 ng mL(-1) and 89.6±1.8 mg 100 mL(-1); P>0.05, respectively). Serum T(3) concentrations, however, were greater in AA goats (1.55±0.03 compared to 1.39±0.04 ng mL(-1)). In addition, a treatment x time interaction occurred (P<0.05) across the experimental period for both T(3) and INS, with increases by the last third of the experimental period, time at which the onset of puberty occurred in both experimental groups. No differences (P>0.05) for glucose concentrations across time occurred between treatments. Results indicate that, in prepuberal goats, glutamate acts as a cue for sexual maturation in a glucose-independent pathway, while both T(3) and INS seem to act as metabolic modulators for the establishment of puberty in goats. Actions of INS and T(3) are mediated directly on hypothalamic centers regulating the pulsatile release of GnRH or indirectly by peripheral cues reflecting INS-T(3) actions on somatic development remains to be determined.
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Affiliation(s)
- C A Meza-Herrera
- Universidad Autónoma Chapingo - Unidad Regional Universitaria de Zonas Áridas. A.P. No. 8, Bermejillo, Durango 35230, Mexico.
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Ojeda SR, Lomniczi A, Loche A, Matagne V, Kaidar G, Sandau US, Dissen GA. The transcriptional control of female puberty. Brain Res 2010; 1364:164-74. [PMID: 20851111 PMCID: PMC2992593 DOI: 10.1016/j.brainres.2010.09.039] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 09/08/2010] [Accepted: 09/09/2010] [Indexed: 12/18/2022]
Abstract
The initiation of mammalian puberty requires a sustained increase in pulsatile release of gonadotrophin releasing hormone (GnRH) from the hypothalamus. This increase is brought about by coordinated changes in transsynaptic and glial-neuronal communication, consisting of an increase in neuronal and glial stimulatory inputs to the GnRH neuronal network and the loss of transsynaptic inhibitory influences. GnRH secretion is stimulated by transsynaptic inputs provided by excitatory amino acids (glutamate) and at least one peptide (kisspeptin), and by glial inputs provided by growth factors and small bioactive molecules. The inhibitory input to GnRH neurons is mostly transsynaptic and provided by GABAergic and opiatergic neurons; however, GABA has also been shown to directly excite GnRH neurons. There are many genes involved in the control of these cellular networks, and hence in the control of the pubertal process as a whole. Our laboratory has proposed the concept that these genes are arranged in overlapping networks internally organized in a hierarchical fashion. According to this concept, the highest level of intra-network control is provided by transcriptional regulators that, by directing expression of key subordinate genes, impose genetic coordination to the neuronal and glial subsets involved in initiating the pubertal process. More recently, we have begun to explore the concept that a more dynamic and encompassing level of integrative coordination is provided by epigenetic mechanisms.
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Affiliation(s)
- Sergio R Ojeda
- Division of Neuroscience, Oregon National Primate Research Center/Oregon Health and Science University, 505 N.W. 185th Avenue, Beaverton, OR 97006, USA.
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Arroyo A, Kim BS, Biehl A, Yeh J, Bett GCL. Expression of kv4.3 voltage-gated potassium channels in rat gonadotrophin-releasing hormone (GnRH) neurons during the estrous cycle. Reprod Sci 2010; 18:136-44. [PMID: 20861393 DOI: 10.1177/1933719110382306] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Regular and timely electrical activity of gonadotrophin-releasing hormone (GnRH) neurons accompanies the pulsatile release of GnRH that plays a central role in regulating fertility. Although transient outward A-type currents (I(A)) have been electrophysiologically identified in GnRH neurons, the molecular identity of the channels that underlie these currents are unknown. Several families of voltage-gated potassium channels can underlie I(A). However, the biophysical properties of I(A) described in previous electrophysiological studies are strongly characteristic of members of the Kv4 family of voltage-gated channels. We, therefore, sought to determine the presence of Kv4 channels in GnRH neurons. We used reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis to determine whether Kv4 messenger RNA (mRNA) and protein are present in the rat medial preoptic area (MPOA) and median eminence (ME). We used double-label immunohistochemistry to determine whether Kv4 colocalized with GnRH cell bodies in the MPOA and GnRH axons in the ME. Kv4.3 channels co-localized with GnRH in the MPOA but not in the ME. Neither Kv4.2 nor Kv4.1 co-localized with GnRH in either the MPOA or the ME. The electrical activity of GnRH neurons changes dramatically during the estrous cycle. We, therefore, studied the change in Kv4.3 expression in GnRH neurons during the estrous cycle. In the estrus phase, 58.05% of GnRH neurons expressed Kv4.3 compared to 74.48% in diestrus-proestrus rats (P < .05). Our data suggest that Kv4.3 is the major molecular component of I(A) in GnRH neurons, and furthermore that the expression of Kv4.3 changes significantly during the rat estrous cycle.
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Affiliation(s)
- Armando Arroyo
- Department of Gynecology-Obstetrics, State University of New York, University at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA.
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Ojeda SR, Dubay C, Lomniczi A, Kaidar G, Matagne V, Sandau US, Dissen GA. Gene networks and the neuroendocrine regulation of puberty. Mol Cell Endocrinol 2010; 324:3-11. [PMID: 20005919 PMCID: PMC2888991 DOI: 10.1016/j.mce.2009.12.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 12/04/2009] [Accepted: 12/04/2009] [Indexed: 01/06/2023]
Abstract
A sustained increase in pulsatile release of gonadotrophin releasing hormone (GnRH) from the hypothalamus is an essential, final event that defines the initiation of mammalian puberty. This increase depends on coordinated changes in transsynaptic and glial-neuronal communication, consisting of activating neuronal and glial excitatory inputs to the GnRH neuronal network and the loss of transsynaptic inhibitory tone. It is now clear that the prevalent excitatory systems stimulating GnRH secretion involve a neuronal component consisting of excitatory amino acids (glutamate) and at least one peptide (kisspeptin), and a glial component that uses growth factors and small molecules for cell-cell signaling. GABAergic and opiatergic neurons provide transsynaptic inhibitory control to the system, but GABA neurons also exert direct excitatory effects on GnRH neurons. The molecular mechanisms that provide encompassing coordination to this cellular network are not known, but they appear to involve a host of functionally related genes hierarchically arranged. We envision that, as observed in other gene networks, the highest level of control in this network is provided by transcriptional regulators that, by directing expression of key subordinate genes, impose an integrative level of coordination to the neuronal and glial subsets involved in initiating the pubertal process. The use of high-throughput and gene manipulation approaches coupled to systems biology strategies should provide not only the experimental bases supporting this concept, but also unveil the existence of crucial components of network control not yet identified.
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Affiliation(s)
- Sergio R Ojeda
- Division of Neuroscience, Oregon National Primate Research Center/Oregon, Health & Science University, 505 N.W. 185th Avenue, Beaverton, OR, USA.
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Armadillo-repeat protein functions: questions for little creatures. Trends Cell Biol 2010; 20:470-81. [PMID: 20688255 DOI: 10.1016/j.tcb.2010.05.003] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 05/11/2010] [Accepted: 05/17/2010] [Indexed: 01/24/2023]
Abstract
Armadillo (ARM)-repeat proteins form a large family with diverse and fundamental functions in many eukaryotes. ARM-repeat proteins have largely been characterised in multicellular organisms and much is known about how a subset of these proteins function. The structure of ARM-repeats allows proteins containing them to be functionally very versatile. Are the ARM-repeat proteins in 'little creatures' as multifunctional as their better-studied relatives? The time is now right to start analysing ARM-repeat proteins in these new systems to better understand their cell biology. Here, we review recent advances in understanding the many cellular roles of both well-known and novel ARM-repeat proteins.
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