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Barbaresi P, Fabri M, Lorenzi T, Sagrati A, Morroni M. Intrinsic organization of the corpus callosum. Front Physiol 2024; 15:1393000. [PMID: 39035452 PMCID: PMC11259024 DOI: 10.3389/fphys.2024.1393000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/16/2024] [Indexed: 07/23/2024] Open
Abstract
The corpus callosum-the largest commissural fiber system connecting the two cerebral hemispheres-is considered essential for bilateral sensory integration and higher cognitive functions. Most studies exploring the corpus callosum have examined either the anatomical, physiological, and neurochemical organization of callosal projections or the functional and/or behavioral aspects of the callosal connections after complete/partial callosotomy or callosal lesion. There are no works that address the intrinsic organization of the corpus callosum. We review the existing information on the activities that take place in the commissure in three sections: I) the topographical and neurochemical organization of the intracallosal fibers, II) the role of glia in the corpus callosum, and III) the role of the intracallosal neurons.
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Affiliation(s)
- Paolo Barbaresi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Mara Fabri
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Teresa Lorenzi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Andrea Sagrati
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Manrico Morroni
- Electron Microscopy Unit, Azienda Ospedaliero-Universitaria, Ancona, Italy
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2
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Kobro-Flatmoen A, Witter MP. Neuronal chemo-architecture of the entorhinal cortex: A comparative review. Eur J Neurosci 2019; 50:3627-3662. [PMID: 31293027 DOI: 10.1111/ejn.14511] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 06/18/2019] [Accepted: 06/27/2019] [Indexed: 11/29/2022]
Abstract
The identification of neuronal markers, that is, molecules selectively present in subsets of neurons, contributes to our understanding of brain areas and the networks within them. Specifically, recognizing the distribution of different neuronal markers facilitates the identification of borders between functionally distinct brain areas. Detailed knowledge about the localization and physiological significance of neuronal markers may also provide clues to generate new hypotheses concerning aspects of normal and abnormal brain functioning. Here, we provide a comprehensive review on the distribution within the entorhinal cortex of neuronal markers and the morphology of the neurons they reveal. Emphasis is on the comparative distribution of several markers, with a focus on, but not restricted to rodent, monkey and human data, allowing to infer connectional features, across species, associated with these markers, based on what is revealed by mainly rodent data. The overall conclusion from this review is that there is an emerging pattern in the distribution of neuronal markers in the entorhinal cortex when aligning data along a comparable coordinate system in various species.
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Affiliation(s)
- Asgeir Kobro-Flatmoen
- Kavli Institute for Systems Neuroscience, Centre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Centre for Cortical Microcircuits, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Menno P Witter
- Kavli Institute for Systems Neuroscience, Centre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Centre for Cortical Microcircuits, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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3
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Ch'ng SS, Fu J, Brown RM, Smith CM, Hossain MA, McDougall SJ, Lawrence AJ. Characterization of the relaxin family peptide receptor 3 system in the mouse bed nucleus of the stria terminalis. J Comp Neurol 2019; 527:2615-2633. [PMID: 30947365 DOI: 10.1002/cne.24695] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 03/19/2019] [Accepted: 03/27/2019] [Indexed: 01/17/2023]
Abstract
The bed nucleus of the stria terminalis (BNST) is a critical node involved in stress and reward-related behaviors. Relaxin family peptide receptor 3 (RXFP3) signaling in the BNST has been implicated in stress-induced alcohol seeking behavior. However, the neurochemical phenotype and connectivity of BNST RXFP3-expressing (RXFP3+) cells have yet to be elucidated. We interrogated the molecular signature and electrophysiological properties of BNST RXFP3+ neurons using a RXFP3-Cre reporter mouse line. BNST RXFP3+ cells are circumscribed to the dorsal BNST (dBNST) and are neurochemically heterogeneous, comprising a mix of inhibitory and excitatory neurons. Immunohistochemistry revealed that ~48% of BNST RXFP3+ neurons are GABAergic, and a quarter of these co-express the calcium-binding protein, calbindin. A subset of BNST RXFP3+ cells (~41%) co-express CaMKIIα, suggesting this subpopulation of BNST RXFP3+ neurons are excitatory. Corroborating this, RNAscope® revealed that ~35% of BNST RXFP3+ cells express vVGluT2 mRNA, indicating a subpopulation of RXFP3+ neurons are glutamatergic. RXFP3+ neurons show direct hyperpolarization to bath application of a selective RXFP3 agonist, RXFP3-A2, while around 50% of cells were depolarised by exogenous corticotrophin releasing factor. In behaviorally naive mice the majority of RXFP3+ neurons were Type II cells exhibiting Ih and T type calcium mediated currents. However, chronic swim stress caused persistent plasticity, decreasing the proportion of neurons that express these channels. These studies are the first to characterize the BNST RXFP3 system in mouse and lay the foundation for future functional studies appraising the role of the murine BNST RXFP3 system in more complex behaviors.
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Affiliation(s)
- Sarah S Ch'ng
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Jingjing Fu
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Robyn M Brown
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Craig M Smith
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | | | - Stuart J McDougall
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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Barbaresi P, Mensà E, Sagrati A, Graciotti L. Postnatal development of the distribution of nitric oxide-producing neurons in the rat corpus callosum. Neurosci Res 2019; 151:15-30. [PMID: 30796928 DOI: 10.1016/j.neures.2019.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/15/2019] [Accepted: 02/14/2019] [Indexed: 11/18/2022]
Abstract
The postnatal development of nitric oxide (NO)-producing intracallosal neurons was studied in rats by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry from postnatal day 0 (P0) to P30. NADPH-d-positive neurons (NADPH-d+Ns) were detected already at P0, mainly in the rostral region of the corpus callosum (cc). Their location and the intensity of staining allowed them to be classified as type I NO-producing neurons. At P0, tufts of intensely labeled fibers, probably corresponding to the callosal septa described in the monkey and human cc, entered the ventral cc region and reached its dorsal portion. From P5, cell bodies and dendrites were often associated to blood vessels. The number of intracallosal NADPH-d+Ns rose in the first postnatal days to peak at P5, it declined until P10, and then remained almost constant until P30. Their size increased from P0 to P30, dramatically so (>65%) from P0 to P15. From P10 onward their distribution was adult-like, i.e. NADPH-d+Ns were more numerous in the lateral and intermediate portions of the cc and diminished close to the midline. In conjunction with previous data, these findings indicate that intracallosal NADPH-d+Ns could have a role in callosal axon guidance, myelination, refinement processes, and callosal blood flow regulation.
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Affiliation(s)
- Paolo Barbaresi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, I-60020, Ancona, Italy.
| | - Emanuela Mensà
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, I-60020, Ancona, Italy; Department of Clinical and Molecular Sciences, Section of Experimental Pathology, Marche Polytechnic University, I-60020, Ancona, Italy
| | - Andrea Sagrati
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, I-60020, Ancona, Italy
| | - Laura Graciotti
- Department of Clinical and Molecular Sciences, Section of Experimental Pathology, Marche Polytechnic University, I-60020, Ancona, Italy
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Substance P receptor in the rat indusium griseum during postnatal development. Neurosci Res 2018; 130:23-38. [DOI: 10.1016/j.neures.2017.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/09/2017] [Accepted: 08/18/2017] [Indexed: 11/21/2022]
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Individual variability in the structural properties of neurons in the human inferior olive. Brain Struct Funct 2017; 223:1667-1681. [PMID: 29189906 DOI: 10.1007/s00429-017-1580-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/26/2017] [Indexed: 12/19/2022]
Abstract
The inferior olive (IO) is the sole source of the climbing fibers innervating the cerebellar cortex. We have previously shown both individual differences in the size and folding pattern of the principal nucleus (IOpr) in humans as well as in the expression of different proteins in IOpr neurons. This high degree of variability was not present in chimpanzee samples. The neurochemical differences might reflect static differences among individuals, but might also reflect age-related processes resulting in alterations of protein synthesis. Several observations support the latter idea. First, accumulation of lipofuscin, the "age pigment" is well documented in IOpr neurons. Second, there are silver- and abnormal tau-immunostained intraneuronal granules in IOpr neurons (Ikeda et al. Neurosci Lett 258:113-116, 1998). Finally, Olszewski and Baxter (Cytoarchitecture of the human brain stem, Second edn. Karger, Basel, 1954) observed an apparent loss of IOpr neurons in older individuals. We have further investigated the possibility of age-related changes in IOpr neurons using silver- and immunostained sections. We found silver-labeled intraneuronal granules in neurons of the IOpr in all human cases studied (n = 17, ages 25-71). We did not, however, confirm immunostaining with antibodies to abnormal tau. There was individual variability in the density of neurons as well as in the expression of the calcium-binding protein calretinin. In the chimpanzee, there were neither silver-stained intraneuronal granules nor irregularities in immunostaining. Overall, the data support the hypothesis that in some, but not all, humans there are functional changes in IOpr neurons and ultimately cell death. Neurochemical changes of IOpr neurons may contribute to age-related changes in motor and cognitive skills mediated by the cerebellum.
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Anatomical and Electrophysiological Clustering of Superficial Medial Entorhinal Cortex Interneurons. eNeuro 2017; 4:eN-NWR-0263-16. [PMID: 29085901 PMCID: PMC5659260 DOI: 10.1523/eneuro.0263-16.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/19/2017] [Accepted: 09/29/2017] [Indexed: 01/03/2023] Open
Abstract
Local GABAergic interneurons regulate the activity of spatially-modulated principal cells in the medial entorhinal cortex (MEC), mediating stellate-to-stellate connectivity and possibly enabling grid formation via recurrent inhibitory circuitry. Despite the important role interneurons seem to play in the MEC cortical circuit, the combination of low cell counts and functional diversity has made systematic electrophysiological studies of these neurons difficult. For these reasons, there remains a paucity of knowledge on the electrophysiological profiles of superficial MEC interneuron populations. Taking advantage of glutamic acid decarboxylase 2 (GAD2)-IRES-tdTomato and PV-tdTomato transgenic mice, we targeted GABAergic interneurons for whole-cell patch-clamp recordings and characterized their passive membrane features, basic input/output properties and action potential (AP) shape. These electrophysiologically characterized cells were then anatomically reconstructed, with emphasis on axonal projections and pial depth. K-means clustering of interneuron anatomical and electrophysiological data optimally classified a population of 106 interneurons into four distinct clusters. The first cluster is comprised of layer 2- and 3-projecting, slow-firing interneurons. The second cluster is comprised largely of PV+ fast-firing interneurons that project mainly to layers 2 and 3. The third cluster contains layer 1- and 2-projecting interneurons, and the fourth cluster is made up of layer 1-projecting horizontal interneurons. These results, among others, will provide greater understanding of the electrophysiological characteristics of MEC interneurons, help guide future in vivo studies, and may aid in uncovering the mechanism of grid field formation.
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Barbaresi P, Mensà E, Bastioli G, Amoroso S. Substance P NK1 receptor in the rat corpus callosum during postnatal development. Brain Behav 2017; 7:e00713. [PMID: 28638718 PMCID: PMC5474716 DOI: 10.1002/brb3.713] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
INTRODUCTION The expression of substance P (SP) receptor (neurokinin 1, NK1) was studied in the rat corpus callosum (cc) from postnatal day 0 (the first 24 hr from birth, P0) to P30. METHODS We used immunocytochemistry to study the presence of intracallosal NK1-immunopositive neurons (NK1IP-n) during cc development. RESULTS NK1IP-n first appeared on P5. Their number increased significantly between P5 and P10, it remained almost constant between P10 and P15, then declined slightly until P30. The size of intracallosal NK1IP-n increased constantly from P5 (102.3 μm2) to P30 (262.07 μm2). From P5 onward, their distribution pattern was adult-like, that is, they were more numerous in the lateral and intermediate parts of the cc, and declined to few or none approaching the midline. At P5, intracallosal NK1IP-n had a predominantly round cell bodies with primary dendrites of different thickness from which originated thinner secondary branches. Between P10 and P15, dendrites were longer and more thickly branched, and displayed several varicosities as well as short, thin appendages. Between P20 and P30, NK1IP-n were qualitatively indistinguishable from those of adult animals and could be classified as bipolar (fusiform and rectangular), round-polygonal, and pyramidal (triangular-pyriform). CONCLUSIONS Number of NK1IP-n increase between P5 and P10, then declines, but unlike other intracallosal neurons, NK1IP-n make up a significant population in the adult cc. These findings suggest that NK1IP-n may be involved in the myelination of callosal axons, could play an important role in their pathfinding. Since they are also found in adult rat cc, it is likely that their role changes during lifetime.
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Affiliation(s)
- Paolo Barbaresi
- Section of Neuroscience and Cell Biology Department of Experimental and Clinical Medicine Marche Polytechnic University Ancona Italy
| | - Emanuela Mensà
- Section of Neuroscience and Cell Biology Department of Experimental and Clinical Medicine Marche Polytechnic University Ancona Italy
| | - Guendalina Bastioli
- Department of Biomedical Sciences and Public Health Marche Polytechnic University Ancona Italy
| | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health Marche Polytechnic University Ancona Italy
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Structural and functional alterations in the prefrontal cortex after post-weaning social isolation: relationship with species-typical and deviant aggression. Brain Struct Funct 2016; 222:1861-1875. [DOI: 10.1007/s00429-016-1312-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 09/13/2016] [Indexed: 12/19/2022]
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10
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Rodriguez AR, de Sevilla Müller LP, Brecha NC. The RNA binding protein RBPMS is a selective marker of ganglion cells in the mammalian retina. J Comp Neurol 2014; 522:1411-43. [PMID: 24318667 DOI: 10.1002/cne.23521] [Citation(s) in RCA: 324] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 11/27/2013] [Accepted: 12/03/2013] [Indexed: 12/12/2022]
Abstract
There are few neurochemical markers that reliably identify retinal ganglion cells (RGCs), which are a heterogeneous population of cells that integrate and transmit the visual signal from the retina to the central visual nuclei. We have developed and characterized a new set of affinity-purified guinea pig and rabbit antibodies against RNA-binding protein with multiple splicing (RBPMS). On western blots these antibodies recognize a single band at 〜24 kDa, corresponding to RBPMS, and they strongly label RGC and displaced RGC (dRGC) somata in mouse, rat, guinea pig, rabbit, and monkey retina. RBPMS-immunoreactive cells and RGCs identified by other techniques have a similar range of somal diameters and areas. The density of RBPMS cells in mouse and rat retina is comparable to earlier semiquantitative estimates of RGCs. RBPMS is mainly expressed in medium and large DAPI-, DRAQ5-, NeuroTrace- and NeuN-stained cells in the ganglion cell layer (GCL), and RBPMS is not expressed in syntaxin (HPC-1)-immunoreactive cells in the inner nuclear layer (INL) and GCL, consistent with their identity as RGCs, and not displaced amacrine cells. In mouse and rat retina, most RBPMS cells are lost following optic nerve crush or transection at 3 weeks, and all Brn3a-, SMI-32-, and melanopsin-immunoreactive RGCs also express RBPMS immunoreactivity. RBPMS immunoreactivity is localized to cyan fluorescent protein (CFP)-fluorescent RGCs in the B6.Cg-Tg(Thy1-CFP)23Jrs/J mouse line. These findings show that antibodies against RBPMS are robust reagents that exclusively identify RGCs and dRGCs in multiple mammalian species, and they will be especially useful for quantification of RGCs.
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Affiliation(s)
- Allen R Rodriguez
- Department of Neurobiology, David Geffen School of Medicine at Los Angeles, University of California at Los Angeles, Los Angeles, California, 90095-1763
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Gonzales KK, Pare JF, Wichmann T, Smith Y. GABAergic inputs from direct and indirect striatal projection neurons onto cholinergic interneurons in the primate putamen. J Comp Neurol 2013; 521:2502-22. [PMID: 23296794 PMCID: PMC3983787 DOI: 10.1002/cne.23295] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/14/2012] [Accepted: 12/27/2012] [Indexed: 01/30/2023]
Abstract
Striatal cholinergic interneurons (ChIs) are involved in reward-dependent learning and the regulation of attention. The activity of these neurons is modulated by intrinsic and extrinsic γ-aminobutyric acid (GABA)ergic and glutamatergic afferents, but the source and relative prevalence of these diverse regulatory inputs remain to be characterized. To address this issue, we performed a quantitative ultrastructural analysis of the GABAergic and glutamatergic innervation of ChIs in the postcommissural putamen of rhesus monkeys. Postembedding immunogold localization of GABA combined with peroxidase immunostaining for choline acetyltransferase showed that 60% of all synaptic inputs to ChIs originate from GABAergic terminals, whereas 21% are from putatively glutamatergic terminals that establish asymmetric synapses, and 19% from other (non-GABAergic) sources of symmetric synapses. Double pre-embedding immunoelectron microscopy using substance P and Met-/Leu-enkephalin antibodies to label GABAergic terminals from collaterals of "direct" and "indirect" striatal projection neurons, respectively, revealed that 47% of the indirect pathway terminals and 36% of the direct pathway terminals target ChIs. Together, substance P- and enkephalin-positive terminals represent 24% of all synapses onto ChIs in the monkey putamen. These findings show that ChIs receive prominent GABAergic inputs from multiple origins, including a significant contingent from axon collaterals of direct and indirect pathway projection neurons.
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Affiliation(s)
- Kalynda Kari Gonzales
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
| | - Jean-Francois Pare
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
| | - Thomas Wichmann
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Department of Neurology, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Department of Neurology, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
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Saiz-Sanchez D, De La Rosa-Prieto C, Ubeda-Bañon I, Martinez-Marcos A. Interneurons and beta-amyloid in the olfactory bulb, anterior olfactory nucleus and olfactory tubercle in APPxPS1 transgenic mice model of Alzheimer's disease. Anat Rec (Hoboken) 2013; 296:1413-23. [PMID: 23904197 DOI: 10.1002/ar.22750] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 06/18/2013] [Indexed: 01/29/2023]
Abstract
Impaired olfaction has been described as an early symptom in Alzheimer's disease (AD). Neuroanatomical changes underlying this deficit in the olfactory system are largely unknown. Given that interneuron populations are crucial in olfactory information processing, we have quantitatively analyzed somatostatin- (SOM), parvalbumin- (PV), and calretinin-expressing (CR) cells in the olfactory bulb, anterior olfactory nucleus, and olfactory tubercle in PS1 x APP double transgenic mice model of AD. The experiments were performed in wild type and double transgenic homozygous animal groups of 2, 4, 6, and 8 months of age to analyze early stages of the pathology. In addition, beta-amyloid (Aβ) expression and its correlation with SOM cells have been quantified under confocal microscopy. The results indicate increasing expressions of Aβ with aging as well as an early fall of SOM and CR expression, whereas PV was decreased later in the disease progression. These observations evidence an early, preferential vulnerability of SOM and CR cells in rostral olfactory structures during AD that may be useful to unravel neural basis of olfactory deficits associated to this neurodegenerative disorder.
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Affiliation(s)
- Daniel Saiz-Sanchez
- Laboratorio de Neuroplasticidad y Neurodegeneración, Departamento de Ciencias Médicas, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
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Dittrich L, Heiss JE, Warrier DR, Perez XA, Quik M, Kilduff TS. Cortical nNOS neurons co-express the NK1 receptor and are depolarized by Substance P in multiple mammalian species. Front Neural Circuits 2012; 6:31. [PMID: 22679419 PMCID: PMC3367498 DOI: 10.3389/fncir.2012.00031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 05/06/2012] [Indexed: 11/17/2022] Open
Abstract
We have previously demonstrated that Type I neuronal nitric oxide synthase (nNOS)-expressing neurons are sleep-active in the cortex of mice, rats, and hamsters. These neurons are known to be GABAergic, to express Neuropeptide Y (NPY) and, in rats, to co-express the Substance P (SP) receptor NK1, suggesting a possible role for SP in sleep/wake regulation. To evaluate the degree of co-expression of nNOS and NK1 in the cortex among mammals, we used double immunofluorescence for nNOS and NK1 and determined the anatomical distribution in mouse, rat, and squirrel monkey cortex. Type I nNOS neurons co-expressed NK1 in all three species although the anatomical distribution within the cortex was species-specific. We then performed in vitro patch clamp recordings in cortical neurons in mouse and rat slices using the SP conjugate tetramethylrhodamine-SP (TMR-SP) to identify NK1-expressing cells and evaluated the effects of SP on these neurons. Bath application of SP (0.03–1 μM) resulted in a sustained increase in firing rate of these neurons; depolarization persisted in the presence of tetrodotoxin. These results suggest a conserved role for SP in the regulation of cortical sleep-active neurons in mammals.
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Affiliation(s)
- Lars Dittrich
- Biosciences Division, Center for Neuroscience, SRI International, Menlo Park CA, USA
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Mesnage B, Gaillard S, Godin AG, Rodeau JL, Hammer M, Von Engelhardt J, Wiseman PW, De Koninck Y, Schlichter R, Cordero-Erausquin M. Morphological and functional characterization of cholinergic interneurons in the dorsal horn of the mouse spinal cord. J Comp Neurol 2012; 519:3139-58. [PMID: 21618225 DOI: 10.1002/cne.22668] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Endogenous acetylcholine is an important modulator of sensory processing, especially at the spinal level, where nociceptive (pain-related) stimuli enter the central nervous system and are integrated before being relayed to the brain. To decipher the organization of the local cholinergic circuitry in the spinal dorsal horn, we used transgenic mice expressing enchanced green fluorescent protein specifically in cholinergic neurons (ChAT::EGFP) and characterized the morphology, neurochemistry, and firing properties of the sparse population of cholinergic interneurons in this area. Three-dimensional reconstruction of lamina III ChAT::EGFP neurons based either on their intrinsic fluorescence or on intracellular labeling in live tissue demonstrated that these neurons have long and thin processes that grow preferentially in the dorsal direction. Their dendrites and axon are highly elongated in the rostrocaudal direction, beyond the limits of a single spinal segment. These unique morphological features suggest that dorsal horn cholinergic interneurons are the main contributors to the plexus of cholinergic processes located in lamina IIi, just dorsal to their cell bodies. In addition, immunostainings demonstrated that dorsal horn cholinergic interneurons in the mouse are γ-aminobutyric acidergic and express nitric oxide synthase, as in rats. Finally, electrophysiological recordings from these neurons in spinal cord slices demonstrate that two-thirds of them have a repetitive spiking pattern with frequent rebound spikes following hyperpolarization. Altogether our results indicate that, although they are rare, the morphological and functional features of cholinergic neurons enable them to collect segmental information in superficial layers of the dorsal horn and to modulate it over several segments.
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Affiliation(s)
- Bruce Mesnage
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 CNRS, Dept. Nociception et Douleur, 67084 Strasbourg, France
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Müller LPDS, Do MTH, Yau KW, He S, Baldridge WH. Tracer coupling of intrinsically photosensitive retinal ganglion cells to amacrine cells in the mouse retina. J Comp Neurol 2011; 518:4813-24. [PMID: 20963830 DOI: 10.1002/cne.22490] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are a subtype of ganglion cell in the mammalian retina that expresses the photopigment melanopsin and drives non-image-forming visual functions. Three morphological subtypes of ipRGCs (M1, M2, and M3) have been described based on their dendritic stratifications in the inner plexiform layer (IPL), but the question of their potential interactions via electrical coupling remains unsettled. In this study, we have addressed this question in the mouse retina by, injecting the tracer Neurobiotin into ipRGCs that had been genetically labelled with the fluorescent protein, tdTomato. We confirmed the presence of the M1-M3 subtypes of ipRGCs based on their distinct dendritic stratifications. All three subtypes were tracer coupled to putative amacrine cells situated within the ganglion cell layer (GCL) but not the inner nuclear layer (INL). The cells tracer coupled to the M1 and M2 cells were shown to be widefield GABA-immunoreactive amacrine cells. We found no evidence of homologous tracer coupling of ipRGCs or heterologous coupling to other types of ganglion cells.
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Suzuki N, Bekkers JM. Inhibitory neurons in the anterior piriform cortex of the mouse: classification using molecular markers. J Comp Neurol 2010; 518:1670-87. [PMID: 20235162 DOI: 10.1002/cne.22295] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The primary olfactory cortex (or piriform cortex, PC) is attracting increasing attention as a model system for the study of cortical sensory processing, yet little is known about inhibitory neurons in the PC. Here we provide the first systematic classification of GABA-releasing interneurons in the anterior PC of mice, based on the expression of molecular markers. Our experiments used GAD67-GFP transgenic mice, in which gamma-aminobutyric acid (GABA)-containing cells are labeled with green fluorescent protein (GFP). We first confirmed, using paired whole-cell recordings, that GFP(+) neurons in the anterior PC of GAD67-GFP mice are functionally GABAergic. Next, we performed immunolabeling of GFP(+) cells to quantify their expression of every possible pairwise combination of seven molecular markers: calbindin, calretinin, parvalbumin, cholecystokinin, neuropeptide Y, somatostatin, and vasoactive intestinal peptide. We found that six main categories of interneurons could be clearly distinguished in the anterior PC, based on the size and laminar location of their somata, intensity of GFP fluorescence, patterns of axonal projections, and expression of one or more of the seven markers. A number of rarer categories of interneurons could also be identified. These data provide a road map for further work that examines the functional properties of the six main classes of interneurons. Together, this information elucidates the cellular architecture of the PC and provides clues about the roles of GABAergic interneurons in olfactory processing.
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Affiliation(s)
- Norimitsu Suzuki
- Neuroscience Program, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia
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Burkhalter A. Many specialists for suppressing cortical excitation. Front Neurosci 2008; 2:155-67. [PMID: 19225588 PMCID: PMC2622740 DOI: 10.3389/neuro.01.026.2008] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2008] [Accepted: 09/18/2008] [Indexed: 12/30/2022] Open
Abstract
Cortical computations are critically dependent on GABA-releasing neurons for dynamically balancing excitation with inhibition that is proportional to the overall level of activity. Although it is widely accepted that there are multiple types of interneurons, defining their identities based on qualitative descriptions of morphological, molecular and physiological features has failed to produce a universally accepted ‘parts list’, which is needed to understand the roles that interneurons play in cortical processing. A list of features has been published by the Petilla Interneurons Nomenclature Group, which represents an important step toward an unbiased classification of interneurons. To this end some essential features have recently been studied quantitatively and their association was examined using multidimensional cluster analyses. These studies revealed at least 3 distinct electrophysiological, 6 morphological and 15 molecular phenotypes. This is a conservative estimate of the number of interneuron types, which almost certainly will be revised as more quantitative studies will be performed and similarities will be defined objectively. It is clear that interneurons are organized with physiological attributes representing the most general, molecular characteristics the most detailed and morphological features occupying the middle ground. By themselves, none of these features are sufficient to define classes of interneurons. The challenge will be to determine which features belong together and how cell type-specific feature combinations are genetically specified.
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Affiliation(s)
- Andreas Burkhalter
- Department of Anatomy and Neurobiology, Washington University School of Medicine St. Louis, MO, USA
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