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Emanuilov AI, Budnik AF, Masliukov PM. Somatostatin-immunoreactive neurons of the rat gut during the development. Histochem Cell Biol 2024:10.1007/s00418-024-02322-9. [PMID: 39153131 DOI: 10.1007/s00418-024-02322-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2024] [Indexed: 08/19/2024]
Abstract
Somatostatin (SST) is a peptide expressed in the peripheral and central nervous systems, as well as in endocrine and immune cells. The aim of the current study is to determine the percentage of SST immunoreactive (IR) neurons and their colocalization with choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS), neuropeptide Y (NPY), and glial fibrillary acidic protein (GFAP) in the myenteric plexus (MP) and submucous plexus (SP) of the small intestine (SI) and large intestine (LI) of rats across different age groups from newborn to senescence using immunohistochemistry. In the MP of the SI and LI, the percentage of SST-IR neurons significantly increased during early postnatal development from 12 ± 2.4 (SI) and 13 ± 3.0 (LI) in newborn rats to 23 ± 1.5 (SI) and 18 ± 1.6 (LI) in 20-day-old animals, remaining stable until 60 days of age. The proportion of SST-IR cells then decreased in aged 2-year-old animals to 14 ± 2.0 (SI) and 10 ± 2.6 (LI). In the SP, the percentage of SST-IR neurons significantly rose from 22 ± 3.2 (SI) and 23 ± 1.7 (LI) in newborn rats to 42 ± 4.0 in 20-day-old animals (SI) and 32 ± 4.9 in 30-day-old animals (LI), before declining in aged 2-year-old animals to 21 ± 2.6 (SI) and 28 ± 7.4 (LI). Between birth and 60 days of age, 97-98% of SST-IR neurons in the MP and SP colocalized with ChAT in both plexuses of the SI and LI. The percentage of SST/ChAT neurons decreased in old rats to 85 ± 5.0 (SI) and 90 ± 3.8 (LI) in the MP and 89 ± 3.2 (SI) and 89 ± 1.6 (LI) in the SP. Conversely, in young rats, only a few SST-IR neurons colocalized with nNOS, but this percentage significantly increased in 2-year-old rats. The percentage of SST/NPY-IR neurons exhibited considerable variation throughout postnatal development, with no significant differences across different age groups in both the MP and SP of both intestines. No colocalization of SST with GFAP was observed in any of the studied animals. In conclusion, the expression of SST in enteric neurons increases in young rats and decreases in senescence, accompanied by changes in SST colocalization with ChAT and nNOS.
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Affiliation(s)
- Andrey I Emanuilov
- Department of Human Anatomy, Yaroslavl State Medical University, Yaroslavl, Russia
| | - Antonina F Budnik
- Department of Normal and Pathological Anatomy, Kabardino-Balkarian State University Named After H.M. Berbekov, Nalchik, Russia
| | - Petr M Masliukov
- Department of Human Anatomy, Yaroslavl State Medical University, Yaroslavl, Russia.
- Department of Normal Physiology and Biophysics, Yaroslavl State Medical University, Revoliucionnaya 5, Yaroslavl, Russia, 150000.
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2
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Stark R. The olfactory bulb: A neuroendocrine spotlight on feeding and metabolism. J Neuroendocrinol 2024; 36:e13382. [PMID: 38468186 DOI: 10.1111/jne.13382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/13/2024]
Abstract
Olfaction is the most ancient sense and is needed for food-seeking, danger protection, mating and survival. It is often the first sensory modality to perceive changes in the external environment, before sight, taste or sound. Odour molecules activate olfactory sensory neurons that reside on the olfactory epithelium in the nasal cavity, which transmits this odour-specific information to the olfactory bulb (OB), where it is relayed to higher brain regions involved in olfactory perception and behaviour. Besides odour processing, recent studies suggest that the OB extends its function into the regulation of food intake and energy balance. Furthermore, numerous hormone receptors associated with appetite and metabolism are expressed within the OB, suggesting a neuroendocrine role outside the hypothalamus. Olfactory cues are important to promote food preparatory behaviours and consumption, such as enhancing appetite and salivation. In addition, altered metabolism or energy state (fasting, satiety and overnutrition) can change olfactory processing and perception. Similarly, various animal models and human pathologies indicate a strong link between olfactory impairment and metabolic dysfunction. Therefore, understanding the nature of this reciprocal relationship is critical to understand how olfactory or metabolic disorders arise. This present review elaborates on the connection between olfaction, feeding behaviour and metabolism and will shed light on the neuroendocrine role of the OB as an interface between the external and internal environments. Elucidating the specific mechanisms by which olfactory signals are integrated and translated into metabolic responses holds promise for the development of targeted therapeutic strategies and interventions aimed at modulating appetite and promoting metabolic health.
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Affiliation(s)
- Romana Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia
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3
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Burton SD, Malyshko CM, Urban NN. Fast-spiking interneuron detonation drives high-fidelity inhibition in the olfactory bulb. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.592874. [PMID: 38766161 PMCID: PMC11100763 DOI: 10.1101/2024.05.07.592874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Inhibitory circuits in the mammalian olfactory bulb (OB) dynamically reformat olfactory information as it propagates from peripheral receptors to downstream cortex. To gain mechanistic insight into how specific OB interneuron types support this sensory processing, we examine unitary synaptic interactions between excitatory mitral and tufted cells (MTCs), the OB projection cells, and a conserved population of anaxonic external plexiform layer interneurons (EPL-INs) using pair and quartet whole-cell recordings in acute mouse brain slices. Physiological, morphological, neurochemical, and synaptic analyses divide EPL-INs into distinct subtypes and reveal that parvalbumin-expressing fast-spiking EPL-INs (FSIs) perisomatically innervate MTCs with release-competent dendrites and synaptically detonate to mediate fast, short-latency recurrent and lateral inhibition. Sparse MTC synchronization supralinearly increases this high-fidelity inhibition, while sensory afferent activation combined with single-cell silencing reveals that individual FSIs account for a substantial fraction of total network-driven MTC lateral inhibition. OB output is thus powerfully shaped by detonation-driven high-fidelity perisomatic inhibition.
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Affiliation(s)
- Shawn D. Burton
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
| | | | - Nathaniel N. Urban
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
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4
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Bao S, Romero JM, Belfort BD, Arenkiel BR. Signaling mechanisms underlying activity-dependent integration of adult-born neurons in the mouse olfactory bulb. Genesis 2024; 62:e23595. [PMID: 38553878 PMCID: PMC10987073 DOI: 10.1002/dvg.23595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/02/2024]
Abstract
Adult neurogenesis has fascinated the field of neuroscience for decades given the prospects of harnessing mechanisms that facilitate the rewiring and/or replacement of adult brain tissue. The subgranular zone of the hippocampus and the subventricular zone of the lateral ventricle are the two main areas in the brain that exhibit ongoing neurogenesis. Of these, adult-born neurons within the olfactory bulb have proven to be a powerful model for studying circuit plasticity, providing a broad and accessible avenue into neuron development, migration, and continued circuit integration within adult brain tissue. This review focuses on some of the recognized molecular and signaling mechanisms underlying activity-dependent adult-born neuron development. Notably, olfactory activity and behavioral states contribute to adult-born neuron plasticity through sensory and centrifugal inputs, in which calcium-dependent transcriptional programs, local translation, and neuropeptide signaling play important roles. This review also highlights areas of needed continued investigation to better understand the remarkable phenomenon of adult-born neuron integration.
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Affiliation(s)
- Suyang Bao
- Development, Disease Models, and Therapeutics Graduate Program, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
| | - Juan M. Romero
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Benjamin D.W. Belfort
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas 77030, USA
- Genetics and Genomics Graduate Program, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Benjamin R. Arenkiel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA
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5
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Pardasani M, Ramakrishnan AM, Mahajan S, Kantroo M, McGowan E, Das S, Srikanth P, Pandey S, Abraham NM. Perceptual learning deficits mediated by somatostatin releasing inhibitory interneurons of olfactory bulb in an early life stress mouse model. Mol Psychiatry 2023; 28:4693-4706. [PMID: 37726451 PMCID: PMC10914616 DOI: 10.1038/s41380-023-02244-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/21/2023]
Abstract
Early life adversity (ELA) causes aberrant functioning of neural circuits affecting the health of an individual. While ELA-induced behavioural disorders resulting from sensory and cognitive disabilities can be assessed clinically, the neural mechanisms need to be probed using animal models by employing multi-pronged experimental approaches. As ELA can alter sensory perception, we investigated the effect of early weaning on murine olfaction. By implementing go/no-go odour discrimination paradigm, we observed olfactory learning and memory impairments in early life stressed (ELS) male mice. As olfactory bulb (OB) circuitry plays a critical role in odour learning, we studied the plausible changes in the OB of ELS mice. Lowered c-Fos activity in the external plexiform layer and a reduction in the number of dendritic processes of somatostatin-releasing, GABAergic interneurons (SOM-INs) in the ELS mice led us to hypothesise the underlying circuit. We recorded reduced synaptic inhibitory feedback on mitral/tufted (M/T) cells, in the OB slices from ELS mice, explaining the learning deficiency caused by compromised refinement of OB output. The reduction in synaptic inhibition was nullified by the photo-activation of ChR2-expressing SOM-INs in ELS mice. The role of SOM-INs was revealed by learning-dependent refinement of Ca2+dynamics quantified by GCaMP6f signals, which was absent in ELS mice. Further, the causal role of SOM-INs involving circuitry was investigated by optogenetic modulation during the odour discrimination learning. Photo-activating these neurons rescued the ELA-induced learning deficits. Conversely, photo-inhibition caused learning deficiency in control animals, while it completely abolished the learning in ELS mice, confirming the adverse effects mediated by SOM-INs. Our results thus establish the role of specific inhibitory circuit in pre-cortical sensory area in orchestrating ELA-dependent changes.
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Affiliation(s)
- Meenakshi Pardasani
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Anantha Maharasi Ramakrishnan
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Sarang Mahajan
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Meher Kantroo
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Eleanor McGowan
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Susobhan Das
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Priyadharshini Srikanth
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Sanyukta Pandey
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India
| | - Nixon M Abraham
- Laboratory of Neural Circuits and Behaviour (LNCB), Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, 411008, India.
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6
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Trejo DH, Ciuparu A, da Silva PG, Velasquez CM, Rebouillat B, Gross MD, Davis MB, Muresan RC, Albeanu DF. Fast updating feedback from piriform cortex to the olfactory bulb relays multimodal reward contingency signals during rule-reversal. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.12.557267. [PMID: 37745564 PMCID: PMC10515864 DOI: 10.1101/2023.09.12.557267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
While animals readily adjust their behavior to adapt to relevant changes in the environment, the neural pathways enabling these changes remain largely unknown. Here, using multiphoton imaging, we investigated whether feedback from the piriform cortex to the olfactory bulb supports such behavioral flexibility. To this end, we engaged head-fixed mice in a multimodal rule-reversal task guided by olfactory and auditory cues. Both odor and, surprisingly, the sound cues triggered cortical bulbar feedback responses which preceded the behavioral report. Responses to the same sensory cue were strongly modulated upon changes in stimulus-reward contingency (rule reversals). The re-shaping of individual bouton responses occurred within seconds of the rule-reversal events and was correlated with changes in the behavior. Optogenetic perturbation of cortical feedback within the bulb disrupted the behavioral performance. Our results indicate that the piriform-to-olfactory bulb feedback carries reward contingency signals and is rapidly re-formatted according to changes in the behavioral context.
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Affiliation(s)
| | - Andrei Ciuparu
- Transylvanian Institute of Neuroscience, Cluj-Napoca, Romania
| | - Pedro Garcia da Silva
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
- current address – Champalimaud Neuroscience Program, Lisbon, Portugal
| | - Cristina M. Velasquez
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
- current address – University of Oxford, UK
| | - Benjamin Rebouillat
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
- current address –École Normale Supérieure, Paris, France
| | | | | | - Raul C. Muresan
- Transylvanian Institute of Neuroscience, Cluj-Napoca, Romania
- STAR-UBB Institute, Babeş-Bolyai University, Cluj-Napoca, Romania
| | - Dinu F. Albeanu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
- School for Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
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7
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Aghvami SS, Kubota Y, Egger V. Anatomical and Functional Connectivity at the Dendrodendritic Reciprocal Mitral Cell–Granule Cell Synapse: Impact on Recurrent and Lateral Inhibition. Front Neural Circuits 2022; 16:933201. [PMID: 35937203 PMCID: PMC9355734 DOI: 10.3389/fncir.2022.933201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 05/27/2022] [Indexed: 11/16/2022] Open
Abstract
In the vertebrate olfactory bulb, reciprocal dendrodendritic interactions between its principal neurons, the mitral and tufted cells, and inhibitory interneurons in the external plexiform layer mediate both recurrent and lateral inhibition, with the most numerous of these interneurons being granule cells. Here, we used recently established anatomical parameters and functional data on unitary synaptic transmission to simulate the strength of recurrent inhibition of mitral cells specifically from the reciprocal spines of rat olfactory bulb granule cells in a quantitative manner. Our functional data allowed us to derive a unitary synaptic conductance on the order of 0.2 nS. The simulations predicted that somatic voltage deflections by even proximal individual granule cell inputs are below the detection threshold and that attenuation with distance is roughly linear, with a passive length constant of 650 μm. However, since recurrent inhibition in the wake of a mitral cell action potential will originate from hundreds of reciprocal spines, the summated recurrent IPSP will be much larger, even though there will be substantial mutual shunting across the many inputs. Next, we updated and refined a preexisting model of connectivity within the entire rat olfactory bulb, first between pairs of mitral and granule cells, to estimate the likelihood and impact of recurrent inhibition depending on the distance between cells. Moreover, to characterize the substrate of lateral inhibition, we estimated the connectivity via granule cells between any two mitral cells or all the mitral cells that belong to a functional glomerular ensemble (i.e., which receive their input from the same glomerulus), again as a function of the distance between mitral cells and/or entire glomerular mitral cell ensembles. Our results predict the extent of the three regimes of anatomical connectivity between glomerular ensembles: high connectivity within a glomerular ensemble and across the first four rings of adjacent glomeruli, substantial connectivity to up to eleven glomeruli away, and negligible connectivity beyond. Finally, in a first attempt to estimate the functional strength of granule-cell mediated lateral inhibition, we combined this anatomical estimate with our above simulation results on attenuation with distance, resulting in slightly narrowed regimes of a functional impact compared to the anatomical connectivity.
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Affiliation(s)
- S. Sara Aghvami
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
| | - Yoshiyuki Kubota
- Division of Cerebral Circuitry, National Institute for Physiological Sciences (NIPS), Okazaki, Japan
| | - Veronica Egger
- Neurophysiology, Institute of Zoology, Regensburg University, Regensburg, Germany
- *Correspondence: Veronica Egger,
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8
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LaFever BJ, Kawasawa YI, Ito A, Imamura F. Pathological consequences of chronic olfactory inflammation on neurite morphology of olfactory bulb projection neurons. Brain Behav Immun Health 2022; 21:100451. [PMID: 35360408 PMCID: PMC8960895 DOI: 10.1016/j.bbih.2022.100451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/10/2022] [Accepted: 03/12/2022] [Indexed: 11/22/2022] Open
Abstract
Chronic olfactory inflammation (COI) in conditions such as chronic rhinosinusitis significantly impairs the functional and anatomical components of the olfactory system. COI induced by intranasal administration of lipopolysaccharide (LPS) results in atrophy, gliosis, and pro-inflammatory cytokine production in the olfactory bulb (OB). Although chronic rhinosinusitis patients have smaller OBs, the consequences of olfactory inflammation on OB neurons are largely unknown. In this study, we investigated the neurological consequences of COI on OB projection neurons, mitral cells (MCs) and tufted cells (TCs). To induce COI, we performed unilateral intranasal administration of LPS to mice for 4 and 10 weeks. Effects of COI on the OB were examined using RNA-sequencing approaches and immunohistochemical analyses. We found that repeated LPS administration upregulated immune-related biological pathways in the OB after 4 weeks. We also determined that the length of TC lateral dendrites in the OB significantly decreased after 10 weeks of COI. The axon initial segment of TCs decreased in number and in length after 10 weeks of COI. The lateral dendrites and axon initial segments of MCs, however, were largely unaffected. In addition, dendritic arborization and AIS reconstruction both took place following a 10-week recovery period. Our findings suggest that olfactory inflammation specifically affects TCs and their integrated circuitry, whereas MCs are potentially protected from this condition. This data demonstrates unique characteristics of the OBs ability to undergo neuroplastic changes in response to stress. Early-stage chronic olfactory inflammation activates the interferon-γ-driven inflammatory pathways in the olfactory bulb. Tufted cells undergo neurite dysregulation in response to chronic olfactory inflammation. Mitral cells and interneurons in the external plexiform layer are largely unaffected by chronic olfactory inflammation. Tufted cells experience complete recovery from neurite dysregulation following a period of ceased inflammation
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Affiliation(s)
- Brandon J. LaFever
- Department of Pharmacology, Penn State College of Medicine, 500 University Dr., Hershey, PA, 17033, USA
| | - Yuka Imamura Kawasawa
- Department of Pharmacology, Penn State College of Medicine, 500 University Dr., Hershey, PA, 17033, USA
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, 500 University Dr., Hershey, PA, 17033, USA
- Institute for Personalized Medicine, Penn State College of Medicine, 500 University Dr., Hershey, PA, 17033, USA
| | - Ayako Ito
- Department of Pharmacology, Penn State College of Medicine, 500 University Dr., Hershey, PA, 17033, USA
| | - Fumiaki Imamura
- Department of Pharmacology, Penn State College of Medicine, 500 University Dr., Hershey, PA, 17033, USA
- Corresponding author. Department of Pharmacology, Penn State College of Medicine, 500 University Drive, Hershey, PA, 17033, USA.
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Wu J, Liu P, Mao X, Qiu F, Gong L, Wu J, Wang D, He M, Li A. Ablation of microRNAs in VIP + interneurons impairs olfactory discrimination and decreases neural activity in the olfactory bulb. Acta Physiol (Oxf) 2022; 234:e13767. [PMID: 34981885 DOI: 10.1111/apha.13767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/18/2021] [Accepted: 01/01/2022] [Indexed: 12/29/2022]
Abstract
AIM MicroRNAs (miRNAs) are abundantly expressed in vasoactive intestinal peptide expressing (VIP+ ) interneurons and are indispensable for their functional maintenance and survival. Here, we blocked miRNA biogenesis in postmitotic VIP+ interneurons in mice by selectively ablating Dicer, an enzyme essential for miRNA maturation, to study whether ablation of VIP+ miRNA affects olfactory function and neural activity in olfactory centres such as the olfactory bulb, which contains a large number of VIP+ interneurons. METHODS A go/no-go odour discrimination task and a food-seeking test were used to assess olfactory discrimination and olfactory detection. In vivo electrophysiological techniques were used to record single units and local field potentials. RESULTS Olfactory detection and olfactory discrimination behaviours were impaired in VIP+ -specific Dicer-knockout mice. In vivo electrophysiological recordings in awake, head-fixed mice showed that both spontaneous and odour-evoked firing rates were decreased in mitral/tufted cells in knockout mice. The power of ongoing and odour-evoked beta local field potentials response of the olfactory bulb and anterior piriform cortex were dramatically decreased. Furthermore, the coherence of theta oscillations between the olfactory bulb and anterior piriform cortex was decreased. Importantly, Dicer knockout restricted to olfactory bulb VIP+ interneurons recapitulated the behavioural and electrophysiological results of the global knockout. CONCLUSIONS VIP+ miRNAs are an important factor in sensory processing, affecting olfactory function and olfactory neural activity.
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Affiliation(s)
- Jing Wu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Penglai Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Xingfeng Mao
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Fang Qiu
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
- Department of Anesthesiology Shenzhen Second People's Hospital/The First Affiliated Hospital of Shenzhen University Shenzhen China
| | - Ling Gong
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
| | - Jinyun Wu
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
| | - Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Miao He
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
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10
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Ito A, Imamura F. Expression of Maf family proteins in glutamatergic neurons of the mouse olfactory bulb. Dev Neurobiol 2021; 82:77-87. [PMID: 34679244 DOI: 10.1002/dneu.22859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/11/2021] [Accepted: 10/14/2021] [Indexed: 11/09/2022]
Abstract
The fate of neurons in the developing brain is largely determined by the combination of transcription factors they express. In particular, stem cells must follow different transcriptional cascades during differentiation in order to generate neurons with different neurotransmitter properties, such as glutamatergic and GABAergic neurons. In the mouse cerebral cortex, it has been shown that large Maf family proteins, MafA, MafB and c-Maf, regulate the development of specific types of GABAergic interneurons but are not expressed in glutamatergic neurons. In this study, we examined the expression of large Maf family proteins in the developing mouse olfactory bulb (OB) by immunohistochemistry and found that the cell populations expressing MafA and MafB are almost identical, and most of them express Tbr2. As Tbr2 is expressed in glutamatergic neurons in the OB, we further examined the expression of glutamatergic and GABAergic neuronal markers in MafA and MafB positive cells. The results showed that in the OB, MafA and MafB are expressed exclusively in glutamatergic neurons, but not in GABAergic neurons. We also found that few cells express c-Maf in the OB. These results indicate that, unlike the cerebral cortex, MafA and/or MafB may regulate the development of glutamatergic neurons in the developing OB. This study advances our knowledge about the development of glutamatergic neurons in the olfactory bulb, and also might suggest that mechanisms for the generation of projection neurons and interneurons differ between the cortex and the olfactory bulb, even though they both develop from the telencephalon.
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Affiliation(s)
- Ayako Ito
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Fumiaki Imamura
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania, USA
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11
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Lage-Rupprecht V, Zhou L, Bianchini G, Aghvami SS, Mueller M, Rózsa B, Sassoè-Pognetto M, Egger V. Presynaptic NMDARs cooperate with local spikes toward GABA release from the reciprocal olfactory bulb granule cell spine. eLife 2020; 9:e63737. [PMID: 33252329 PMCID: PMC7704106 DOI: 10.7554/elife.63737] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022] Open
Abstract
In the rodent olfactory bulb the smooth dendrites of the principal glutamatergic mitral cells (MCs) form reciprocal dendrodendritic synapses with large spines on GABAergic granule cells (GC), where unitary release of glutamate can trigger postsynaptic local activation of voltage-gated Na+-channels (Navs), that is a spine spike. Can such single MC input evoke reciprocal release? We find that unitary-like activation via two-photon uncaging of glutamate causes GC spines to release GABA both synchronously and asynchronously onto MC dendrites. This release indeed requires activation of Navs and high-voltage-activated Ca2+-channels (HVACCs), but also of NMDA receptors (NMDAR). Simulations show temporally overlapping HVACC- and NMDAR-mediated Ca2+-currents during the spine spike, and ultrastructural data prove NMDAR presence within the GABAergic presynapse. This cooperative action of presynaptic NMDARs allows to implement synapse-specific, activity-dependent lateral inhibition, and thus could provide an efficient solution to combinatorial percept synthesis in a sensory system with many receptor channels.
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Affiliation(s)
- Vanessa Lage-Rupprecht
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
- Department of Bioinformatics, Fraunhofer SCAISankt AugustinGermany
| | - Li Zhou
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
| | - Gaia Bianchini
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
| | - S Sara Aghvami
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
- School of Electrical and Computer Engineering, University of TehranTehranIslamic Republic of Iran
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM)TehranIslamic Republic of Iran
| | - Max Mueller
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
| | - Balázs Rózsa
- Two-Photon Imaging Center, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapestHungary
| | | | - Veronica Egger
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
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12
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Egger V, Diamond JS. A17 Amacrine Cells and Olfactory Granule Cells: Parallel Processors of Early Sensory Information. Front Cell Neurosci 2020; 14:600537. [PMID: 33250720 PMCID: PMC7674606 DOI: 10.3389/fncel.2020.600537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 10/05/2020] [Indexed: 12/16/2022] Open
Abstract
Neurons typically receive synaptic input in their dendritic arbor, integrate inputs in their soma, and send output action potentials through their axon, following Cajal's law of dynamic polarization. Two notable exceptions are retinal amacrine cells and olfactory granule cells (GCs), which flout Cajal's edict by providing synaptic output from the same dendrites that collect synaptic input. Amacrine cells, a diverse cell class comprising >60 subtypes, employ various dendritic input/output strategies, but A17 amacrine cells (A17s) in particular share further interesting functional characteristics with GCs: both receive excitatory synaptic input from neurons in the primary glutamatergic pathway and return immediate, reciprocal feedback via GABAergic inhibitory synapses to the same synaptic terminals that provided input. Both neurons thereby process signals locally within their dendrites, shaping many parallels, signaling pathways independently. The similarities between A17s and GCs cast into relief striking differences that may indicate distinct processing roles within their respective circuits: First, they employ partially dissimilar molecular mechanisms to transform excitatory input into inhibitory output; second, GCs fire action potentials, whereas A17s do not. Third, GC signals may be influenced by cortical feedback, whereas the mammalian retina receives no such retrograde input. Finally, A17s constitute just one subtype within a diverse class that is specialized in a particular task, whereas the more homogeneous GCs may play more diverse signaling roles via multiple processing modes. Here, we review these analogies and distinctions between A17 amacrine cells and granule cells, hoping to gain further insight into the operating principles of these two sensory circuits.
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Affiliation(s)
- Veronica Egger
- Department of Neurophysiology, Institute of Zoology, Universität Regensburg, Regensburg, Germany
| | - Jeffrey S. Diamond
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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13
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Imamura F, Ito A, LaFever BJ. Subpopulations of Projection Neurons in the Olfactory Bulb. Front Neural Circuits 2020; 14:561822. [PMID: 32982699 PMCID: PMC7485133 DOI: 10.3389/fncir.2020.561822] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 08/12/2020] [Indexed: 12/17/2022] Open
Abstract
Generation of neuronal diversity is a biological strategy widely used in the brain to process complex information. The olfactory bulb is the first relay station of olfactory information in the vertebrate central nervous system. In the olfactory bulb, axons of the olfactory sensory neurons form synapses with dendrites of projection neurons that transmit the olfactory information to the olfactory cortex. Historically, the olfactory bulb projection neurons have been classified into two populations, mitral cells and tufted cells. The somata of these cells are distinctly segregated within the layers of the olfactory bulb; the mitral cells are located in the mitral cell layer while the tufted cells are found in the external plexiform layer. Although mitral and tufted cells share many morphological, biophysical, and molecular characteristics, they differ in soma size, projection patterns of their dendrites and axons, and odor responses. In addition, tufted cells are further subclassified based on the relative depth of their somata location in the external plexiform layer. Evidence suggests that different types of tufted cells have distinct cellular properties and play different roles in olfactory information processing. Therefore, mitral and different types of tufted cells are considered as starting points for parallel pathways of olfactory information processing in the brain. Moreover, recent studies suggest that mitral cells also consist of heterogeneous subpopulations with different cellular properties despite the fact that the mitral cell layer is a single-cell layer. In this review, we first compare the morphology of projection neurons in the olfactory bulb of different vertebrate species. Next, we explore the similarities and differences among subpopulations of projection neurons in the rodent olfactory bulb. We also discuss the timing of neurogenesis as a factor for the generation of projection neuron heterogeneity in the olfactory bulb. Knowledge about the subpopulations of olfactory bulb projection neurons will contribute to a better understanding of the complex olfactory information processing in higher brain regions.
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Affiliation(s)
- Fumiaki Imamura
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
| | - Ayako Ito
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
| | - Brandon J LaFever
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
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14
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Saiz-Sanchez D, Ubeda-Bañon I, Flores-Cuadrado A, Gonzalez-Rodriguez M, Villar-Conde S, Astillero-Lopez V, Martinez-Marcos A. Somatostatin, Olfaction, and Neurodegeneration. Front Neurosci 2020; 14:96. [PMID: 32140092 PMCID: PMC7042373 DOI: 10.3389/fnins.2020.00096] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 01/23/2020] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's and Parkinson's diseases are the most prevalent neurodegenerative disorders in aging. Hyposmia has been described as an early symptom that can precede cognitive and motor deficits by decades. Certain regions within the olfactory system, such as the anterior olfactory nucleus, display the neuropathological markers tau and amyloid-β or α-synuclein from the earliest stages of disease progression in a preferential manner. Specific neuronal subpopulations, namely those expressing somatostatin (SST), are preferentially affected throughout the olfactory and limbic systems. SST is a neuropeptide present in a subpopulation of GABAergic interneurons throughout the brain and its main function is to inhibit principal neurons and/or other interneurons. It has been reported that SST expression is reduced by 50% in Alzheimer's disease and that it is related to the formation of Aβ oligomers. The mechanisms underlying the preferential vulnerability of SST-expressing neurons in Alzheimer's disease (and, to a minor extent, in Parkinson's disease) are not known but analysis of the available data could shed light on their etiology. This short review aims to update the knowledge of functional features of somatostatin within the olfactory system and its role in olfactory deficits during neurodegeneration.
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Affiliation(s)
- Daniel Saiz-Sanchez
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Isabel Ubeda-Bañon
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Alicia Flores-Cuadrado
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Melania Gonzalez-Rodriguez
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Sandra Villar-Conde
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Veronica Astillero-Lopez
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Alino Martinez-Marcos
- Neuroplasticity and Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, Ciudad Real, Spain
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15
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Riedemann T. Diversity and Function of Somatostatin-Expressing Interneurons in the Cerebral Cortex. Int J Mol Sci 2019; 20:E2952. [PMID: 31212931 PMCID: PMC6627222 DOI: 10.3390/ijms20122952] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 06/08/2019] [Accepted: 06/14/2019] [Indexed: 02/01/2023] Open
Abstract
Inhibitory interneurons make up around 10-20% of the total neuron population in the cerebral cortex. A hallmark of inhibitory interneurons is their remarkable diversity in terms of morphology, synaptic connectivity, electrophysiological and neurochemical properties. It is generally understood that there are three distinct and non-overlapping interneuron classes in the mouse neocortex, namely, parvalbumin-expressing, 5-HT3A receptor-expressing and somatostatin-expressing interneuron classes. Each class is, in turn, composed of a multitude of subclasses, resulting in a growing number of interneuron classes and subclasses. In this review, I will focus on the diversity of somatostatin-expressing interneurons (SOM+ INs) in the cerebral cortex and elucidate their function in cortical circuits. I will then discuss pathological consequences of a malfunctioning of SOM+ INs in neurological disorders such as major depressive disorder, and present future avenues in SOM research and brain pathologies.
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Affiliation(s)
- Therese Riedemann
- Ludwig-Maximilians-University, Biomedical Center, Physiological Genomics, Großhaderner Str. 9, 82152 Planegg-Martinsried, Germany.
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16
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Nocera S, Simon A, Fiquet O, Chen Y, Gascuel J, Datiche F, Schneider N, Epelbaum J, Viollet C. Somatostatin Serves a Modulatory Role in the Mouse Olfactory Bulb: Neuroanatomical and Behavioral Evidence. Front Behav Neurosci 2019; 13:61. [PMID: 31024270 PMCID: PMC6465642 DOI: 10.3389/fnbeh.2019.00061] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 03/12/2019] [Indexed: 11/30/2022] Open
Abstract
Somatostatin (SOM) and somatostatin receptors (SSTR1-4) are present in all olfactory structures, including the olfactory bulb (OB), where SOM modulates physiological gamma rhythms and olfactory discrimination responses. In this work, histological, viral tracing and transgenic approaches were used to characterize SOM cellular targets in the murine OB. We demonstrate that SOM targets all levels of mitral dendritic processes in the OB with somatostatin receptor 2 (SSTR2) detected in the dendrites of previously uncharacterized mitral-like cells. We show that inhibitory interneurons of the glomerular layer (GL) express SSTR4 while SSTR3 is confined to the granule cell layer (GCL). Furthermore, SOM cells in the OB receive synaptic inputs from olfactory cortical afferents. Behavioral studies demonstrate that genetic deletion of SSTR4, SSTR2 or SOM differentially affects olfactory performance. SOM or SSTR4 deletion have no major effect on olfactory behavioral performances while SSTR2 deletion impacts olfactory detection and discrimination behaviors. Altogether, these results describe novel anatomical and behavioral contributions of SOM, SSTR2 and SSTR4 receptors in olfactory processing.
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Affiliation(s)
- Sonia Nocera
- INSERM, UMR 894-Center for Psychiatry and Neuroscience (CPN), Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Axelle Simon
- INSERM, UMR 894-Center for Psychiatry and Neuroscience (CPN), Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Oriane Fiquet
- INSERM, UMR 894-Center for Psychiatry and Neuroscience (CPN), Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Ying Chen
- INSERM, UMR 894-Center for Psychiatry and Neuroscience (CPN), Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Jean Gascuel
- CNRS UMR 6265—Centre des Sciences du Goût et de l’Alimentation (CSGA), Dijon, France
| | - Frédérique Datiche
- CNRS UMR 6265—Centre des Sciences du Goût et de l’Alimentation (CSGA), Dijon, France
| | - Nanette Schneider
- CNRS UMR 6265—Centre des Sciences du Goût et de l’Alimentation (CSGA), Dijon, France
| | - Jacques Epelbaum
- INSERM, UMR 894-Center for Psychiatry and Neuroscience (CPN), Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Cécile Viollet
- INSERM, UMR 894-Center for Psychiatry and Neuroscience (CPN), Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, Paris, France
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17
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Kovner R, Fox AS, French DA, Roseboom PH, Oler JA, Fudge JL, Kalin NH. Somatostatin Gene and Protein Expression in the Non-human Primate Central Extended Amygdala. Neuroscience 2019; 400:157-168. [PMID: 30610938 DOI: 10.1016/j.neuroscience.2018.12.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/04/2018] [Accepted: 12/20/2018] [Indexed: 12/26/2022]
Abstract
Alterations in central extended amygdala (EAc) function have been linked to anxiety, depression, and anxious temperament (AT), the early-life risk to develop these disorders. The EAc is composed of the central nucleus of the amygdala (Ce), the bed nucleus of the stria terminalis (BST), and the sublenticular extended amygdala (SLEA). Using a non-human primate model of AT and multimodal neuroimaging, the Ce and the BST were identified as key AT-related regions. Both areas are primarily comprised of GABAergic neurons and the lateral Ce (CeL) and lateral BST (BSTL) have among the highest expression of neuropeptides in the brain. Somatostatin (SST) is of particular interest because mouse studies demonstrate that SST neurons, along with corticotropin-releasing factor (CRF) neurons, contribute to a threat-relevant EAc microcircuit. Although the distribution of CeL and BSTL SST neurons has been explored in rodents, this system is not well described in non-human primates. In situ hybridization demonstrated an anterior-posterior gradient of SST mRNA in the CeL but not the BSTL of non-human primates. Triple-labeling immunofluorescence staining revealed that SST protein-expressing cell bodies are a small proportion of the total CeL and BSTL neurons and have considerable co-labeling with CRF. The SLEA exhibited strong SST mRNA and protein expression, suggesting a role for SST in mediating information transfer between the CeL and BSTL. These data provide the foundation for mechanistic non-human primate studies focused on understanding EAc function in neuropsychiatric disorders.
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Affiliation(s)
- Rothem Kovner
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA; Neuroscience Training Program, University of Wisconsin, Madison, WI, USA; HealthEmotions Research Institute, University of Wisconsin, Madison, WI, USA.
| | - Andrew S Fox
- Department of Psychology, University of California, Davis, CA, USA; California National Primate Research Center, University of California, Davis, CA, USA
| | - Delores A French
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA; HealthEmotions Research Institute, University of Wisconsin, Madison, WI, USA
| | - Patrick H Roseboom
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA; HealthEmotions Research Institute, University of Wisconsin, Madison, WI, USA
| | - Jonathan A Oler
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA; HealthEmotions Research Institute, University of Wisconsin, Madison, WI, USA
| | - Julie L Fudge
- Department of Psychiatry, Rochester, NY, USA; Department of Neuroscience, Rochester, NY, USA
| | - Ned H Kalin
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA; Neuroscience Training Program, University of Wisconsin, Madison, WI, USA; HealthEmotions Research Institute, University of Wisconsin, Madison, WI, USA.
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18
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Microglia Play an Active Role in Obesity-Associated Cognitive Decline. J Neurosci 2018; 38:8889-8904. [PMID: 30201764 DOI: 10.1523/jneurosci.0789-18.2018] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/26/2018] [Accepted: 08/20/2018] [Indexed: 12/17/2022] Open
Abstract
Obesity affects >600 million people worldwide, a staggering number that appears to be on the rise. One of the lesser known consequences of obesity is its deleterious effects on cognition, which have been well documented across many cognitive domains and age groups. To investigate the cellular mechanisms that underlie obesity-associated cognitive decline, we used diet-induced obesity in male mice and found memory impairments along with reductions in dendritic spines, sites of excitatory synapses, increases in the activation of microglia, the brain's resident immune cells, and increases in synaptic profiles within microglia, in the hippocampus, a brain region linked to cognition. We found that partial knockdown of the receptor for fractalkine, a chemokine that can serve as a "find me" cue for microglia, prevented microglial activation and cognitive decline induced by obesity. Furthermore, we found that pharmacological inhibition of microglial activation in obese mice was associated with prevention of both dendritic spine loss and cognitive degradation. Finally, we observed that pharmacological blockade of microglial phagocytosis lessened obesity-associated cognitive decline. These findings suggest that microglia play an active role in obesity-associated cognitive decline by phagocytosis of synapses that are important for optimal function.SIGNIFICANCE STATEMENT Obesity in humans correlates with reduced cognitive function. To investigate the cellular mechanisms underlying this, we used diet-induced obesity in mice and found impaired performance on cognitive tests of hippocampal function. These deficits were accompanied by reduced numbers of dendritic spines, increased microglial activation, and increased synaptic profiles within microglia. Inhibition of microglial activation by transgenic and pharmacological methods prevented cognitive decline and dendritic spine loss in obese mice. Moreover, pharmacological inhibition of the phagocytic activity of microglia was also sufficient to prevent cognitive degradation. This work suggests that microglia may be responsible for obesity-associated cognitive decline and dendritic spine loss.
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19
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Liu X, Liu S. Cholecystokinin selectively activates short axon cells to enhance inhibition of olfactory bulb output neurons. J Physiol 2018; 596:2185-2207. [PMID: 29572837 DOI: 10.1113/jp275511] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/15/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cholecystokinin (CCK) via CCK-B receptors significantly enhances the GABAA receptor-mediated synaptic inhibition of principal olfactory bulb (OB) output neurons. This CCK action requires action potentials in presynaptic neurons. The enhanced inhibition of OB output neurons is a result of CCK-elevated inhibitory input from the glomerular circuit. CCK modulation of the glomerular circuit also leads to potentiated presynaptic inhibition of olfactory nerve terminals and postsynaptic inhibition of glomerular neurons. Selective excitation of short axon cells underlies the CCK-potentiated glomerular inhibition. ABSTRACT Neuropeptides such as cholecystokinin (CCK) are important for many brain functions, including sensory processing. CCK is predominantly present in a subpopulation of excitatory neurons and activation of CCK receptors is implicated in olfactory signal processing in the olfactory bulb (OB). However, the cellular and circuit mechanisms underlying the actions of CCK in the OB remain elusive. In the present study, we characterized the effects of CCK on synaptic inhibition of the principal OB output neurons mitral/tufted cells (MTCs) followed by mechanistic analyses at both circuit and cellular levels. First, we found that CCK via CCK-B receptors enhances the GABAA receptor-mediated spontaneous IPSCs in MTCs. Second, CCK does not affect the action potential independent miniature IPSCs in MTCs. Third, CCK potentiates glomerular inhibition resulting in increased GABAB receptor-mediated presynaptic inhibition of olfactory nerve terminals and enhanced spontaneous IPSCs in MTCs and glomerular neurons. Fourth, CCK enhances miniature IPSCs in the excitatory external tufted cells, although neither in the inhibitory short axon cells (SACs) nor in periglomerular cells (PGCs). Finally, CCK excites all tested SACs and a very small minority of GABAergic neurons in the granule cell layer or in periglomerular cells, but not in deep SACs. These results demonstrate that CCK selectively activates SACs to engage the SAC-formed interglomerular circuit and thus elevates inhibition broadly in the OB glomerular layer. This modulation may prevent the system from saturating in response to a high concentration of odourants or facilitate the detection of weak stimuli by increasing signal-to-noise ratio.
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Affiliation(s)
- Xiang Liu
- Department of Anatomy & Neurobiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Shaolin Liu
- Department of Anatomy & Neurobiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA
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20
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Ubeda-Bañon I, Flores-Cuadrado A, Saiz-Sanchez D, Martinez-Marcos A. Differential Effects of Parkinson's Disease on Interneuron Subtypes within the Human Anterior Olfactory Nucleus. Front Neuroanat 2017; 11:113. [PMID: 29259548 PMCID: PMC5723292 DOI: 10.3389/fnana.2017.00113] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 11/21/2017] [Indexed: 11/13/2022] Open
Abstract
Synucleinopathies (including α-synucleinopathies), which include Parkinson's disease (PD), manifest themsevles early on (stage 1) in the olfactory system; preferentially in the anterior olfactory nucleus (AON). In particular, the non-motor, early manifestations of PD include hyposmia, which is the partial loss of the sense of smell. The neural basis of hyposmia in PD, however, is poorly understood; but the AON appears to be a key structure in the disease's progression. We analyzed whether α-synuclein was involved in the differential interneuron vulnerability associated with PD in the retrobulbar, cortical anterior and cortical posterior divisions of the AON. First, we determined the expression of the calcium binding interneuron markers, calretinin, calbindin and parvalbumin, as well as non-calcium binding interneuron marker, somatostatin, in neuronal cell bodies alone (cells/mm2) and in neuronal cell bodies and neurites (% of area fraction) of post-mortem tissue from PD cases and age-matched controls (n = 4 for each) by immunofluorescent confocal microscopy. Results indicated that parvalbumin expression was upregulated in neuronal cell bodies throughout the anterior olfactory nucleus of PD cases compared with controls. Furthermore, there was increased calbindin, calretinin and parvalbumin expression in the cell bodies and neurites of neurons in the retrobulbar division and also increased parvalbumin expression in the neurites of neurons in the cortical division; calretinin expression was also increased in neuronal cell bodies and neurites in the cortical posterior division. Second, we analyzed the co-localization of the above markers with α-synuclein, with results indicating that α-synuclein co-localized with the calcium-binding proteins, but only partially with somatostatin. Taken together, these results indicate differential expression levels among different neural markers in the divisions of the AON in PD cases and point to several possibilities, among them: possible neuroprotective mechanisms of calcium-binding proteins against α-synuclein; and the differential involvement of somatostatin in α-synuclein-positive cell bodies and neurites.
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Affiliation(s)
- Isabel Ubeda-Bañon
- Neuroplasticity and Neurodegeneration Laboratory, CRIB, Ciudad Real Medical School, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Alicia Flores-Cuadrado
- Neuroplasticity and Neurodegeneration Laboratory, CRIB, Ciudad Real Medical School, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Daniel Saiz-Sanchez
- Neuroplasticity and Neurodegeneration Laboratory, CRIB, Ciudad Real Medical School, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Alino Martinez-Marcos
- Neuroplasticity and Neurodegeneration Laboratory, CRIB, Ciudad Real Medical School, University of Castilla-La Mancha, Ciudad Real, Spain
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21
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Burton SD. Inhibitory circuits of the mammalian main olfactory bulb. J Neurophysiol 2017; 118:2034-2051. [PMID: 28724776 DOI: 10.1152/jn.00109.2017] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 01/15/2023] Open
Abstract
Synaptic inhibition critically influences sensory processing throughout the mammalian brain, including the main olfactory bulb (MOB), the first station of sensory processing in the olfactory system. Decades of research across numerous laboratories have established a central role for granule cells (GCs), the most abundant GABAergic interneuron type in the MOB, in the precise regulation of principal mitral and tufted cell (M/TC) firing rates and synchrony through lateral and recurrent inhibitory mechanisms. In addition to GCs, however, the MOB contains a vast diversity of other GABAergic interneuron types, and recent findings suggest that, while fewer in number, these oft-ignored interneurons are just as important as GCs in shaping odor-evoked M/TC activity. Here I challenge the prevailing centrality of GCs. In this review, I first outline the specific properties of each GABAergic interneuron type in the rodent MOB, with particular emphasis placed on direct interneuron recordings and cell type-selective manipulations. On the basis of these properties, I then critically reevaluate the contribution of GCs vs. other interneuron types to the regulation of odor-evoked M/TC firing rates and synchrony via lateral, recurrent, and other inhibitory mechanisms. This analysis yields a novel model in which multiple interneuron types with distinct abundances, connectivity patterns, and physiologies complement one another to regulate M/TC activity and sensory processing.
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Affiliation(s)
- Shawn D Burton
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania; and .,Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania
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22
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Olfactory bulb plasticity ensures proper olfaction after severe impairment in postnatal neurogenesis. Sci Rep 2017; 7:5654. [PMID: 28720887 PMCID: PMC5516035 DOI: 10.1038/s41598-017-05970-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 06/06/2017] [Indexed: 11/08/2022] Open
Abstract
The olfactory bulb (OB) neurons establish a complex network that ensures the correct processing of the olfactory inputs. Moreover, the OB presents a lifelong addition of new neurons into its existing circuitry. This neurogenesis is considered essential for the OB function. However, its functional impact on physiology and behavior is still unclear. Here, we investigate the mechanisms of OB plasticity that underlie bulbar physiology in relation to severe damage of neurogenesis. The neurogenesis of young mice was altered by ionizing radiation. Afterwards, both multi-channel olfactometry and electrophysiological studies were performed. Furthermore, neurogenesis and differentiation of the newly formed cells were assessed using bromodeoxyuridine labeling combined with a wide battery of neuronal markers. Our results demonstrate a reduction in both neurogenesis and volume of the OB in irradiated animals. The number of neuroblasts reaching the OB was reduced and their differentiation rate into interneurons selectively changed; some populations were noticeably affected whereas others remained preserved. Surprisingly, both olfactory detection and discrimination as well as electrophysiology presented almost no alterations in irradiated mice. Our findings suggest that after damaging postnatal neurogenesis, the neurochemical fate of some interneurons changes within a new biological scenario, while maintaining homeostasis and olfaction.
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23
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Task Learning Promotes Plasticity of Interneuron Connectivity Maps in the Olfactory Bulb. J Neurosci 2017; 36:8856-71. [PMID: 27559168 DOI: 10.1523/jneurosci.0794-16.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 07/08/2016] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED Elucidating patterns of functional synaptic connectivity and deciphering mechanisms of how plasticity influences such connectivity is essential toward understanding brain function. In the mouse olfactory bulb (OB), principal neurons (mitral/tufted cells) make reciprocal connections with local inhibitory interneurons, including granule cells (GCs) and external plexiform layer (EPL) interneurons. Our current understanding of the functional connectivity between these cell types, as well as their experience-dependent plasticity, remains incomplete. By combining acousto-optic deflector-based scanning microscopy and genetically targeted expression of Channelrhodopsin-2, we mapped connections in a cell-type-specific manner between mitral cells (MCs) and GCs or between MCs and EPL interneurons. We found that EPL interneurons form broad patterns of connectivity with MCs, whereas GCs make more restricted connections with MCs. Using an olfactory associative learning paradigm, we found that these circuits displayed differential features of experience-dependent plasticity. Whereas reciprocal connectivity between MCs and EPL interneurons was nonplastic, the connections between GCs and MCs were dynamic and adaptive. Interestingly, experience-dependent plasticity of GCs occurred only in certain stages of neuronal maturation. We show that different interneuron subtypes form distinct connectivity maps and modes of experience-dependent plasticity in the OB, which may reflect their unique functional roles in information processing. SIGNIFICANCE STATEMENT Deducing how specific interneuron subtypes contribute to normal circuit function requires understanding the dynamics of their connections. In the olfactory bulb (OB), diverse interneuron subtypes vastly outnumber principal excitatory cells. By combining acousto-optic deflector-based scanning microscopy, electrophysiology, and genetically targeted expression of Channelrhodopsin-2, we mapped the functional connectivity between mitral cells (MCs) and OB interneurons in a cell-type-specific manner. We found that, whereas external plexiform layer (EPL) interneurons show broadly distributed patterns of stable connectivity with MCs, adult-born granule cells show dynamic and plastic patterns of synaptic connectivity with task learning. Together, these findings reveal the diverse roles for interneuons within sensory circuits toward information learning and processing.
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Viollet C, Simon A, Tolle V, Labarthe A, Grouselle D, Loe-Mie Y, Simonneau M, Martel G, Epelbaum J. Somatostatin-IRES-Cre Mice: Between Knockout and Wild-Type? Front Endocrinol (Lausanne) 2017; 8:131. [PMID: 28674519 PMCID: PMC5474965 DOI: 10.3389/fendo.2017.00131] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/29/2017] [Indexed: 01/24/2023] Open
Abstract
The neuropeptide somatostatin (SOM) is widely expressed in rodent brain and somatostatin-IRES-Cre (SOM-cre) mouse strains are increasingly used to unravel the physiology of SOM-containing neurons. However, while knock-in targeting strategy greatly improves Cre-Lox system accuracy, recent reports have shown that genomic insertion of Cre construct per se can markedly affect physiological function. We show that Cre transgene insertion into the 3'UTR of the somatostatin gene leads to the selective and massive depletion of endogenous SOM in all tested brain regions. It also strongly impacts SOM-related neuroendocrine responses in a similar manner to what has been reported for SST KO mice: increased corticosterone levels after 30-min restraint stress, decreased amplitude and regularity of ultradian growth hormone secretory patterns accompanied by changes in sexually dimorphic liver gene expression (serpina1, Cyp2b9, Cyp2a4, Cyp2d9, and Cyp7b1). In addition to demonstrating the need for examination of the consequences of Cre transgenesis, these results also reveal how this SOM-cre strain may be a useful tool in studying the functional consequences of moderate to low SOM levels as reported in neurological and psychiatric disorders.
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Affiliation(s)
- Cécile Viollet
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
- *Correspondence: Cécile Viollet, ; Jacques Epelbaum,
| | - Axelle Simon
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
| | - Virginie Tolle
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
| | - Alexandra Labarthe
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
| | - Dominique Grouselle
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
| | - Yann Loe-Mie
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
| | - Michel Simonneau
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, Orsay, France
| | - Guillaume Martel
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
| | - Jacques Epelbaum
- INSERM U894, Centre de Psychiatrie et Neurosciences, Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France
- MECADEV UMR 7179 CNRS, Muséum National d’Histoire Naturelle, Brunoy, France
- *Correspondence: Cécile Viollet, ; Jacques Epelbaum,
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Llona I, Farías P, Troc-Gajardo JL. Early Postnatal Development of Somastostatinergic Systems in Brainstem Respiratory Network. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1015:131-144. [DOI: 10.1007/978-3-319-62817-2_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Liguz-Lecznar M, Urban-Ciecko J, Kossut M. Somatostatin and Somatostatin-Containing Neurons in Shaping Neuronal Activity and Plasticity. Front Neural Circuits 2016; 10:48. [PMID: 27445703 PMCID: PMC4927943 DOI: 10.3389/fncir.2016.00048] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/20/2016] [Indexed: 01/27/2023] Open
Abstract
Since its discovery over four decades ago, somatostatin (SOM) receives growing scientific and clinical interest. Being localized in the nervous system in a subset of interneurons somatostatin acts as a neurotransmitter or neuromodulator and its role in the fine-tuning of neuronal activity and involvement in synaptic plasticity and memory formation are widely recognized in the recent literature. Combining transgenic animals with electrophysiological, anatomical and molecular methods allowed to characterize several subpopulations of somatostatin-containing interneurons possessing specific anatomical and physiological features engaged in controlling the output of cortical excitatory neurons. Special characteristic and connectivity of somatostatin-containing neurons set them up as significant players in shaping activity and plasticity of the nervous system. However, somatostatin is not just a marker of particular interneuronal subpopulation. Somatostatin itself acts pre- and postsynaptically, modulating excitability and neuronal responses. In the present review, we combine the knowledge regarding somatostatin and somatostatin-containing interneurons, trying to incorporate it into the current view concerning the role of the somatostatinergic system in cortical plasticity.
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Affiliation(s)
- Monika Liguz-Lecznar
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology Warsaw, Poland
| | - Joanna Urban-Ciecko
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental BiologyWarsaw, Poland; Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon UniversityPittsburgh, PA, USA
| | - Malgorzata Kossut
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental BiologyWarsaw, Poland; Department of Psychology, University of Social Sciences and Humanities (SWPS)Warsaw, Poland
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Villette V, Guigue P, Picardo MA, Sousa VH, Leprince E, Lachamp P, Malvache A, Tressard T, Cossart R, Baude A. Development of early-born γ-Aminobutyric acid hub neurons in mouse hippocampus from embryogenesis to adulthood. J Comp Neurol 2016; 524:2440-61. [PMID: 26779909 PMCID: PMC4949683 DOI: 10.1002/cne.23961] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 12/04/2015] [Accepted: 01/03/2016] [Indexed: 02/02/2023]
Abstract
Early‐born γ‐aminobutyric acid (GABA) neurons (EBGNs) are major components of the hippocampal circuit because at early postnatal stages they form a subpopulation of “hub cells” transiently supporting CA3 network synchronization (Picardo et al. [2011] Neuron 71:695–709). It is therefore essential to determine when these cells acquire the remarkable morphofunctional attributes supporting their network function and whether they develop into a specific subtype of interneuron into adulthood. Inducible genetic fate mapping conveniently allows for the labeling of EBGNs throughout their life. EBGNs were first analyzed during the perinatal week. We observed that EBGNs acquired mature characteristics at the time when the first synapse‐driven synchronous activities appeared in the form of giant depolarizing potentials. The fate of EBGNs was next analyzed in the adult hippocampus by using anatomical characterization. Adult EBGNs included a significant proportion of cells projecting selectively to the septum; in turn, EBGNs were targeted by septal and entorhinal inputs. In addition, most EBGNs were strongly targeted by cholinergic and monoaminergic terminals, suggesting significant subcortical innervation. Finally, we found that some EBGNs located in the septum or the entorhinal cortex also displayed a long‐range projection that we traced to the hippocampus. Therefore, this study shows that the maturation of the morphophysiological properties of EBGNs mirrors the evolution of early network dynamics, suggesting that both phenomena may be causally linked. We propose that a subpopulation of EBGNs forms into adulthood a scaffold of GABAergic projection neurons linking the hippocampus to distant structures. J. Comp. Neurol. 524:2440–2461, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vincent Villette
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Philippe Guigue
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Michel Aimé Picardo
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Vitor Hugo Sousa
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Erwan Leprince
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Philippe Lachamp
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Arnaud Malvache
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Thomas Tressard
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Rosa Cossart
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
| | - Agnès Baude
- INSERM U901, Marseille, 13009, France.,Aix-Marseille University, UMR 901, Marseille, 13009, France.,INMED, Marseille, 13009, France
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Rapid Feedforward Inhibition and Asynchronous Excitation Regulate Granule Cell Activity in the Mammalian Main Olfactory Bulb. J Neurosci 2016; 35:14103-22. [PMID: 26490853 DOI: 10.1523/jneurosci.0746-15.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Granule cell-mediated inhibition is critical to patterning principal neuron activity in the olfactory bulb, and perturbation of synaptic input to granule cells significantly alters olfactory-guided behavior. Despite the critical role of granule cells in olfaction, little is known about how sensory input recruits granule cells. Here, we combined whole-cell patch-clamp electrophysiology in acute mouse olfactory bulb slices with biophysical multicompartmental modeling to investigate the synaptic basis of granule cell recruitment. Physiological activation of sensory afferents within single glomeruli evoked diverse modes of granule cell activity, including subthreshold depolarization, spikelets, and suprathreshold responses with widely distributed spike latencies. The generation of these diverse activity modes depended, in part, on the asynchronous time course of synaptic excitation onto granule cells, which lasted several hundred milliseconds. In addition to asynchronous excitation, each granule cell also received synchronous feedforward inhibition. This inhibition targeted both proximal somatodendritic and distal apical dendritic domains of granule cells, was reliably recruited across sniff rhythms, and scaled in strength with excitation as more glomeruli were activated. Feedforward inhibition onto granule cells originated from deep short-axon cells, which responded to glomerular activation with highly reliable, short-latency firing consistent with tufted cell-mediated excitation. Simulations showed that feedforward inhibition interacts with asynchronous excitation to broaden granule cell spike latency distributions and significantly attenuates granule cell depolarization within local subcellular compartments. Collectively, our results thus identify feedforward inhibition onto granule cells as a core feature of olfactory bulb circuitry and establish asynchronous excitation and feedforward inhibition as critical regulators of granule cell activity. SIGNIFICANCE STATEMENT Inhibitory granule cells are involved critically in shaping odor-evoked principal neuron activity in the mammalian olfactory bulb, yet little is known about how sensory input activates granule cells. Here, we show that sensory input to the olfactory bulb evokes a barrage of asynchronous synaptic excitation and highly reliable, short-latency synaptic inhibition onto granule cells via a disynaptic feedforward inhibitory circuit involving deep short-axon cells. Feedforward inhibition attenuates local depolarization within granule cell dendritic branches, interacts with asynchronous excitation to suppress granule cell spike-timing precision, and scales in strength with excitation across different levels of sensory input to normalize granule cell firing rates.
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Lepousez G, Nissant A, Lledo PM. Adult Neurogenesis and the Future of the Rejuvenating Brain Circuits. Neuron 2015; 86:387-401. [DOI: 10.1016/j.neuron.2015.01.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Bartel DL, Rela L, Hsieh L, Greer CA. Dendrodendritic synapses in the mouse olfactory bulb external plexiform layer. J Comp Neurol 2015; 523:1145-61. [PMID: 25420934 DOI: 10.1002/cne.23714] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 11/18/2014] [Accepted: 11/20/2014] [Indexed: 12/31/2022]
Abstract
Odor information relayed by olfactory bulb projection neurons, mitral and tufted cells (M/T), is modulated by pairs of reciprocal dendrodendritic synaptic circuits in the external plexiform layer (EPL). Interneurons, which are accounted for largely by granule cells, receive depolarizing input from M/T dendrites and in turn inhibit current spread in M/T dendrites via hyperpolarizing reciprocal dendrodendritic synapses. Because the location of dendrodendritic synapses may significantly affect the cascade of odor information, we assessed synaptic properties and density within sublaminae of the EPL and along the length of M/T secondary dendrites. In electron micrographs the M/T to granule cell synapse appeared to predominate and was equivalent in both the outer and inner EPL. However, the dendrodendritic synapses from granule cell spines onto M/T dendrites were more prevalent in the outer EPL. In contrast, individual gephyrin-immunoreactive (IR) puncta, a postsynaptic scaffolding protein at inhibitory synapses used here as a proxy for the granule to M/T dendritic synapse was equally distributed throughout the EPL. Of significance to the organization of intrabulbar circuits, gephyrin-IR synapses are not uniformly distributed along M/T secondary dendrites. Synaptic density, expressed as a function of surface area, increases distal to the cell body. Furthermore, the distributions of gephyrin-IR puncta are heterogeneous and appear as clusters along the length of the M/T dendrites. Consistent with computational models, our data suggest that temporal coding in M/T cells is achieved by precisely located inhibitory input and that distance from the soma is compensated for by an increase in synaptic density.
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Affiliation(s)
- Dianna L Bartel
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, 06520-8082
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31
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Martel G, Simon A, Nocera S, Kalainathan S, Pidoux L, Blum D, Leclère-Turbant S, Diaz J, Geny D, Moyse E, Videau C, Buée L, Epelbaum J, Viollet C. Aging, but not tau pathology, impacts olfactory performances and somatostatin systems in THY-Tau22 mice. Neurobiol Aging 2014; 36:1013-28. [PMID: 25433460 DOI: 10.1016/j.neurobiolaging.2014.10.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 10/01/2014] [Accepted: 10/24/2014] [Indexed: 11/15/2022]
Abstract
Somatostatin (SOM) cortical levels decline in Alzheimer's disease (AD) in correlation with cognitive impairment severity, the latter being closely related to the presence of neurofibrillary tangles. Impaired olfaction is another hallmark of AD tightly related to tau pathology in the olfactory pathways. Recent studies showed that SOM modulates olfactory processing, suggesting that alterations in SOM levels participate to olfactory deficits in AD. Herein, we first observed that human olfactory peduncle and cortex are enriched in SOM cells and fibers, in aged postmortem brains. Then, the possible link between SOM alterations and olfactory deficits was evaluated by exploring the impact of age and tau hyperphosphorylation on olfactory SOM networks and behavioral performances in THY-Tau22 mice, a tauopathy transgenic model. Distinct molecular repertoires of SOM peptide and receptors were associated to sensory or cortical olfactory processing structures. Aging mainly affected SOM neurotransmission in piriform and entorhinal cortex in wild-type mice, although olfactory performances decreased. However, no further olfactory impairment was evidenced in THY-Tau22 mice until 12 months although tau pathology early affected olfactory cortical structures. Thus, tau hyperphosphorylation per se has a limited impact on olfactory performances in THY-Tau22 mice.
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Affiliation(s)
- Guillaume Martel
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Axelle Simon
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Sonia Nocera
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Sahana Kalainathan
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Ludivine Pidoux
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - David Blum
- Inserm, UMR837, Jean-Pierre Aubert Research Centre, IMPRT, F-59000, Lille, France; Université de Lille, UDSL, F-59000, Lille, France
| | | | - Jorge Diaz
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - David Geny
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Emmanuel Moyse
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Catherine Videau
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Luc Buée
- Inserm, UMR837, Jean-Pierre Aubert Research Centre, IMPRT, F-59000, Lille, France; Université de Lille, UDSL, F-59000, Lille, France
| | - Jacques Epelbaum
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Cécile Viollet
- Inserm, UMR894, Center for Psychiatry & Neuroscience, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France.
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Al Koborssy D, Palouzier-Paulignan B, Salem R, Thevenet M, Romestaing C, Julliard AK. Cellular and molecular cues of glucose sensing in the rat olfactory bulb. Front Neurosci 2014; 8:333. [PMID: 25400540 PMCID: PMC4212682 DOI: 10.3389/fnins.2014.00333] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 10/03/2014] [Indexed: 11/13/2022] Open
Abstract
In the brain, glucose homeostasis of extracellular fluid is crucial to the point that systems specifically dedicated to glucose sensing are found in areas involved in energy regulation and feeding behavior. Olfaction is a major sensory modality regulating food consumption. Nutritional status in turn modulates olfactory detection. Recently it has been proposed that some olfactory bulb (OB) neurons respond to glucose similarly to hypothalamic neurons. However, the precise molecular cues governing glucose sensing in the OB are largely unknown. To decrypt these molecular mechanisms, we first used immunostaining to demonstrate a strong expression of two neuronal markers of glucose-sensitivity, insulin-dependent glucose transporter type 4 (GLUT4), and sodium glucose co-transporter type 1 (SGLT1) in specific OB layers. We showed that expression and mapping of GLUT4 but not SGLT1 were feeding state-dependent. In order to investigate the impact of metabolic status on the delivery of blood-borne glucose to the OB, we measured extracellular fluid glucose concentration using glucose biosensors simultaneously in the OB and cortex of anesthetized rats. We showed that glucose concentration in the OB is higher than in the cortex, that metabolic steady-state glucose concentration is independent of feeding state in the two brain areas, and that acute changes in glycemic conditions affect bulbar glucose concentration alone. These data provide new evidence of a direct relationship between the OB and peripheral metabolism, and emphasize the importance of glucose for the OB network, providing strong arguments toward establishing the OB as a glucose-sensing organ.
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Affiliation(s)
- Dolly Al Koborssy
- Team "Olfaction: From Coding to Memory," Lyon Neuroscience Center, INSERM U1028-CNRS, University Lyon 1 Lyon, France
| | - Brigitte Palouzier-Paulignan
- Team "Olfaction: From Coding to Memory," Lyon Neuroscience Center, INSERM U1028-CNRS, University Lyon 1 Lyon, France
| | - Rita Salem
- Team "Olfaction: From Coding to Memory," Lyon Neuroscience Center, INSERM U1028-CNRS, University Lyon 1 Lyon, France
| | - Marc Thevenet
- Team "Olfaction: From Coding to Memory," Lyon Neuroscience Center, INSERM U1028-CNRS, University Lyon 1 Lyon, France
| | - Caroline Romestaing
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés CNRS 5023, University Lyon 1, Bâtiments Darwin C and Forel Villeurbanne, France
| | - A Karyn Julliard
- Team "Olfaction: From Coding to Memory," Lyon Neuroscience Center, INSERM U1028-CNRS, University Lyon 1 Lyon, France
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Local corticotropin releasing hormone (CRH) signals to its receptor CRHR1 during postnatal development of the mouse olfactory bulb. Brain Struct Funct 2014; 221:1-20. [PMID: 25224546 DOI: 10.1007/s00429-014-0888-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 09/09/2014] [Indexed: 02/07/2023]
Abstract
Neuropeptides play important physiological functions during distinct behaviors such as arousal, learning, memory, and reproduction. However, the role of local, extrahypothalamic neuropeptide signaling in shaping synapse formation and neuronal plasticity in the brain is not well understood. Here, we characterize the spatiotemporal expression profile of the neuropeptide corticotropin-releasing hormone (CRH) and its receptor CRHR1 in the mouse OB throughout development. We found that CRH-expressing interneurons are present in the external plexiform layer, that its cognate receptor is expressed by granule cells, and show that both CRH and CRHR1 expression enriches in the postnatal period when olfaction becomes important towards olfactory-related behaviors. Further, we provide electrophysiological evidence that CRHR1-expressing granule cells functionally respond to CRH ligand, and that the physiological circuitry of CRHR1 knockout mice is abnormal, leading to impaired olfactory behaviors. Together, these data suggest a physiologically relevant role for local CRH signaling towards shaping the neuronal circuitry within the mouse OB.
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Garcia I, Quast KB, Huang L, Herman AM, Selever J, Deussing JM, Justice NJ, Arenkiel BR. Local CRH signaling promotes synaptogenesis and circuit integration of adult-born neurons. Dev Cell 2014; 30:645-59. [PMID: 25199688 DOI: 10.1016/j.devcel.2014.07.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 05/02/2014] [Accepted: 06/30/2014] [Indexed: 01/09/2023]
Abstract
Neural activity either enhances or impairs de novo synaptogenesis and circuit integration of neurons, but how this activity is mechanistically relayed in the adult brain is largely unknown. Neuropeptide-expressing interneurons are widespread throughout the brain and are key candidates for conveying neural activity downstream via neuromodulatory pathways that are distinct from classical neurotransmission. With the goal of identifying signaling mechanisms that underlie neuronal circuit integration in the adult brain, we have virally traced local corticotropin-releasing hormone (CRH)-expressing inhibitory interneurons with extensive presynaptic inputs onto new neurons that are continuously integrated into the adult rodent olfactory bulb. Local CRH signaling onto adult-born neurons promotes and/or stabilizes chemical synapses in the olfactory bulb, revealing a neuromodulatory mechanism for continued circuit plasticity, synapse formation, and integration of new neurons in the adult brain.
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Affiliation(s)
- Isabella Garcia
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Medical Scientist Training Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kathleen B Quast
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Longwen Huang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alexander M Herman
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jennifer Selever
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jan M Deussing
- Max Planck Institute of Psychiatry, 80804 Munich, Germany
| | - Nicholas J Justice
- Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Benjamin R Arenkiel
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA.
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Nagayama S, Homma R, Imamura F. Neuronal organization of olfactory bulb circuits. Front Neural Circuits 2014; 8:98. [PMID: 25232305 PMCID: PMC4153298 DOI: 10.3389/fncir.2014.00098] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/29/2014] [Indexed: 12/31/2022] Open
Abstract
Olfactory sensory neurons extend their axons solely to the olfactory bulb, which is dedicated to odor information processing. The olfactory bulb is divided into multiple layers, with different types of neurons found in each of the layers. Therefore, neurons in the olfactory bulb have conventionally been categorized based on the layers in which their cell bodies are found; namely, juxtaglomerular cells in the glomerular layer, tufted cells in the external plexiform layer, mitral cells in the mitral cell layer, and granule cells in the granule cell layer. More recently, numerous studies have revealed the heterogeneous nature of each of these cell types, allowing them to be further divided into subclasses based on differences in morphological, molecular, and electrophysiological properties. In addition, technical developments and advances have resulted in an increasing number of studies regarding cell types other than the conventionally categorized ones described above, including short-axon cells and adult-generated interneurons. Thus, the expanding diversity of cells in the olfactory bulb is now being acknowledged. However, our current understanding of olfactory bulb neuronal circuits is mostly based on the conventional and simplest classification of cell types. Few studies have taken neuronal diversity into account for understanding the function of the neuronal circuits in this region of the brain. This oversight may contribute to the roadblocks in developing more precise and accurate models of olfactory neuronal networks. The purpose of this review is therefore to discuss the expanse of existing work on neuronal diversity in the olfactory bulb up to this point, so as to provide an overall picture of the olfactory bulb circuit.
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Affiliation(s)
- Shin Nagayama
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston Houston, TX, USA
| | - Ryota Homma
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston Houston, TX, USA
| | - Fumiaki Imamura
- Department of Pharmacology, Pennsylvania State University College of Medicine Hershey, PA, USA
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Ma J, Yao XH, Fu Y, Yu YC. Development of Layer 1 Neurons in the Mouse Neocortex. Cereb Cortex 2014; 24:2604-18. [DOI: 10.1093/cercor/bht114] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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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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The production of somatostatin interneurons in the olfactory bulb is regulated by the transcription factor sp8. PLoS One 2013; 8:e70049. [PMID: 23894587 PMCID: PMC3720950 DOI: 10.1371/journal.pone.0070049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 06/17/2013] [Indexed: 11/19/2022] Open
Abstract
Somatostatin (Som), one of the most concentrated neuropeptides in the brain, is highly expressed in the olfactory bulb (OB). However, the temporal profile by which OB somatostatin-expressing (Som+) interneurons are produced and the molecular mechanisms controlling this profile are totally unknown. In the present study, we found that all the Som+ interneurons in the mouse external plexiform layer (EPL) and the rat glomerular layer (GL) express the transcription factor Sp8.Using the 5-bromo-2'-deoxyuridine (BrdU) birth dating method, combined with immunostaining, we showed that the generation of Som+ interneurons in the mouse and rat OB is confined to the later embryonic and earlier postnatal stages. Within the mouse OB, the production of Som+ interneurons is maximal during late embryogenesis and decreases after birth, whereas the generation of Som+ interneurons is low during embryogenesis and increases gradually after birth in the rat OB. Interestingly, genetic ablation of Sp8 by cre/loxP-based recombination severely reduces the number of Som+ interneurons in the EPL of the mouse OB. Taken together, these results suggest that Sp8 is required for the normal production of Som+ interneurons in the EPL of the mouse OB.
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Cox DJ, Racca C. Differential dendritic targeting of AMPA receptor subunit mRNAs in adult rat hippocampal principal neurons and interneurons. J Comp Neurol 2013; 521:1954-2007. [DOI: 10.1002/cne.23292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022]
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Huang L, Garcia I, Jen HI, Arenkiel BR. Reciprocal connectivity between mitral cells and external plexiform layer interneurons in the mouse olfactory bulb. Front Neural Circuits 2013; 7:32. [PMID: 23459611 PMCID: PMC3584718 DOI: 10.3389/fncir.2013.00032] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 02/12/2013] [Indexed: 01/03/2023] Open
Abstract
Proper brain function relies on exquisite balance between excitation and inhibition, where inhibitory circuits play fundamental roles toward sculpting principle neuron output and information processing. In prominent models of olfactory bulb circuitry, inhibition of mitral cells by local interneurons sharpens odor tuning and provides contrast enhancement. Mitral cell inhibition occurs at both mitral cell apical dendrites and deep-layer dendrodendritic synapses between granule cells, the most abundant population of inhibitory interneurons in the olfactory bulb. However, it remains unclear whether other local interneurons make inhibitory connections onto mitral cells. Here, we report a novel circuitry with strong and reciprocal connectivity between a subpopulation of previously uncharacterized Corticotropin-Releasing Hormone (CRH)-expressing interneurons located in the external plexiform layer (EPL), and mitral cells. Using cell type-specific genetic manipulations, imaging, optogenetic stimulation, and electrophysiological recordings, we reveal that CRH-expressing EPL interneurons strongly inhibit mitral cell firing, and that they are reciprocally excited by fast glutamatergic mitral cell input. These findings functionally identify a novel subpopulation of olfactory bulb interneurons that show reciprocal connectivity with mitral cells, uncovering a previously unknown, and potentially critical player in olfactory bulb circuitry that may influence lateral interactions and/or facilitate odor processing.
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Affiliation(s)
- Longwen Huang
- Department of Neuroscience, Baylor College of Medicine, Texas Children's Hospital Houston, TX, USA
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Characterization of immature and mature 5-hydroxytryptamine 3A receptor-expressing cells within the adult SVZ–RMS–OB system. Neuroscience 2012; 227:180-90. [DOI: 10.1016/j.neuroscience.2012.09.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 09/23/2012] [Accepted: 09/24/2012] [Indexed: 12/19/2022]
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Noam Y, Phan L, McClelland S, Manders EM, Ehrengruber MU, Wadman WJ, Baram TZ, Chen Y. Distinct regional and subcellular localization of the actin-binding protein filamin A in the mature rat brain. J Comp Neurol 2012; 520:3013-34. [PMID: 22434607 DOI: 10.1002/cne.23106] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Filamin A (FLNa) is an actin-binding protein that regulates cell motility, adhesion, and elasticity by cross-linking filamentous actin. Additional roles of FLNa include regulation of protein trafficking and surface expression. Although the functions of FLNa during brain development are well studied, little is known on its expression, distribution, and function in the adult brain. Here we characterize in detail the neuroanatomical distribution and subcellular localization of FLNa in the mature rat brain, by using two antisera directed against epitopes at either the N' or the C' terminus of the protein, further validated by mRNA expression. FLNa was widely and selectively expressed throughout the brain, and the intensity of immunoreactivity was region dependent. The most intensely FLNa-labeled neurons were found in discrete neuronal systems, including basal forebrain structures, anterior nuclear group of thalamus, and hypothalamic parvocellular neurons. Pyramidal neurons in neocortex and hippocampus and magnocellular cells in basolateral amygdaloid nucleus were also intensely FLNa immunoreactive, and strong FLNa labeling was evident in the pontine and medullary raphe nuclei and in sensory and spinal trigeminal nuclei. The subcellular localization of FLNa was evaluated in situ as well as in primary hippocampal neurons. Punctate expression was found in somata and along the dendritic shaft, but FLNa was not detected in dendritic spines. These subcellular distribution patterns were recapitulated in hippocampal and neocortical pyramidal neurons in vivo. The characterization of the expression and subcellular localization of FLNa may provide new clues to the functional roles of this cytoskeletal protein in the adult brain.
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Affiliation(s)
- Yoav Noam
- Department of Anatomy/Neurobiology, University of California-Irvine, Irvine, California 92697-4475, USA
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Palouzier-Paulignan B, Lacroix MC, Aimé P, Baly C, Caillol M, Congar P, Julliard AK, Tucker K, Fadool DA. Olfaction under metabolic influences. Chem Senses 2012; 37:769-97. [PMID: 22832483 PMCID: PMC3529618 DOI: 10.1093/chemse/bjs059] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Recently published work and emerging research efforts have suggested that the olfactory system is intimately linked with the endocrine systems that regulate or modify energy balance. Although much attention has been focused on the parallels between taste transduction and neuroendocrine controls of digestion due to the novel discovery of taste receptors and molecular components shared by the tongue and gut, the equivalent body of knowledge that has accumulated for the olfactory system, has largely been overlooked. During regular cycles of food intake or disorders of endocrine function, olfaction is modulated in response to changing levels of various molecules, such as ghrelin, orexins, neuropeptide Y, insulin, leptin, and cholecystokinin. In view of the worldwide health concern regarding the rising incidence of diabetes, obesity, and related metabolic disorders, we present a comprehensive review that addresses the current knowledge of hormonal modulation of olfactory perception and how disruption of hormonal signaling in the olfactory system can affect energy homeostasis.
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Affiliation(s)
- Brigitte Palouzier-Paulignan
- Centre de Recherche des Neurosciences de Lyon, Equipe Olfaction du Codage à la Mémoire, INSERM U 1028/CNRS 5292, Université de Lyon150 Ave. Tony Garnier, 69366, Lyon, Cedex 07,France
- Equal contribution
| | - Marie-Christine Lacroix
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
- Equal contribution
| | - Pascaline Aimé
- Centre de Recherche des Neurosciences de Lyon, Equipe Olfaction du Codage à la Mémoire, INSERM U 1028/CNRS 5292, Université de Lyon150 Ave. Tony Garnier, 69366, Lyon, Cedex 07,France
| | - Christine Baly
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
| | - Monique Caillol
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
| | - Patrice Congar
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
| | - A. Karyn Julliard
- Centre de Recherche des Neurosciences de Lyon, Equipe Olfaction du Codage à la Mémoire, INSERM U 1028/CNRS 5292, Université de Lyon150 Ave. Tony Garnier, 69366, Lyon, Cedex 07,France
| | - Kristal Tucker
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of MedicinePittsburgh, PA 15261USAand
| | - Debra Ann Fadool
- Department of Biological Science, Programs in Neuroscience and Molecular Biophysics, The Florida State UniversityTallahassee, FL 32306-4295USA
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Martel G, Dutar P, Epelbaum J, Viollet C. Somatostatinergic systems: an update on brain functions in normal and pathological aging. Front Endocrinol (Lausanne) 2012; 3:154. [PMID: 23230430 PMCID: PMC3515867 DOI: 10.3389/fendo.2012.00154] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 11/20/2012] [Indexed: 11/29/2022] Open
Abstract
Somatostatin is highly expressed in mammalian brain and is involved in many brain functions such as motor activity, sleep, sensory, and cognitive processes. Five somatostatin receptors have been described: sst(1), sst(2) (A and B), sst(3), sst(4), and sst(5), all belonging to the G-protein-coupled receptor family. During the recent years, numerous studies contributed to clarify the role of somatostatin systems, especially long-range somatostatinergic interneurons, in several functions they have been previously involved in. New advances have also been made on the alterations of somatostatinergic systems in several brain diseases and on the potential therapeutic target they represent in these pathologies.
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Affiliation(s)
| | | | | | - Cécile Viollet
- *Correspondence: Cécile Viollet, Inserm UMR894 - Center for Psychiatry and Neuroscience, Université Paris Descartes, Sorbonne Paris Cité, 2 ter rue d’Alésia, 75014 Paris, France. e-mail:
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Arenkiel BR, Hasegawa H, Yi JJ, Larsen RS, Wallace ML, Philpot BD, Wang F, Ehlers MD. Activity-induced remodeling of olfactory bulb microcircuits revealed by monosynaptic tracing. PLoS One 2011; 6:e29423. [PMID: 22216277 PMCID: PMC3247270 DOI: 10.1371/journal.pone.0029423] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 11/28/2011] [Indexed: 12/21/2022] Open
Abstract
The continued addition of new neurons to mature olfactory circuits represents a remarkable mode of cellular and structural brain plasticity. However, the anatomical configuration of newly established circuits, the types and numbers of neurons that form new synaptic connections, and the effect of sensory experience on synaptic connectivity in the olfactory bulb remain poorly understood. Using in vivo electroporation and monosynaptic tracing, we show that postnatal-born granule cells form synaptic connections with centrifugal inputs and mitral/tufted cells in the mouse olfactory bulb. In addition, newly born granule cells receive extensive input from local inhibitory short axon cells, a poorly understood cell population. The connectivity of short axon cells shows clustered organization, and their synaptic input onto newborn granule cells dramatically and selectively expands with odor stimulation. Our findings suggest that sensory experience promotes the synaptic integration of new neurons into cell type-specific olfactory circuits.
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Affiliation(s)
- Benjamin R. Arenkiel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (BRA); (MDE)
| | - Hiroshi Hasegawa
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
| | - Jason J. Yi
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
| | - Rylan S. Larsen
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Michael L. Wallace
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Benjamin D. Philpot
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Neurodevelopmental Disorders Research Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Fan Wang
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
| | - Michael D. Ehlers
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut, United States of America
- * E-mail: (BRA); (MDE)
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Radojevic V, Hanusek C, Setz C, Brand Y, Kapfhammer JP, Bodmer D. The somatostatinergic system in the mammalian cochlea. BMC Neurosci 2011; 12:89. [PMID: 21896184 PMCID: PMC3176192 DOI: 10.1186/1471-2202-12-89] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Accepted: 09/06/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Little is known about expression and function of the somatostatinergic system in the mammalian cochlea. We have previously shown that somatostatin administration may have a protective effect on gentamicin-induced hair cell loss. In this study, we have analyzed the cochlear expression of somatostatin receptor 1 (SST1) and somatostatin receptor 2 (SST2) at both the mRNA and the protein level in wild-type mice, as well as in SST1 and SST2 knock-out (KO) mice and in cultivated neurosensory cells. RESULTS We demonstrate that the somatostatin receptors SST1 and SST2 are specifically expressed in outer and inner hair cells (HCs) of the organ of Corti (OC), as well as in defined supporting cells. The expression of SST1 and SST2 receptors in cultivated P5 mouse OC explants was similar to their expression in inner and outer hair cells. Somatostatin itself was not expressed in the mammalian cochlea, suggesting that somatostatin reaches its receptors either through the blood-labyrinthine barrier from the systemic circulation or via the endolymphatic duct from the endolymphatic sac. We used mice with a deletion of either SST1 or SST2 to learn more about the regulation of SST1 and SST2 receptor expression. We demonstrate that in SST1 KO mice, SST2 was expressed in outer HCs and Deiters' cells, but not in pillar cells or inner HCs, as compared with wild-type mice. In contrast, in SST2 KO mice, the expression pattern of the SST1 receptor was not altered relative to wild-type mice. CONCLUSIONS These findings reveal that somatostatin receptors demonstrate specific expression in HCs and supporting cells of the mouse cochlea, and that absence of SST1 alters the expression of SST2. This specific expression pattern suggests that somatostatin receptors may have important functional roles in the inner ear.
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Affiliation(s)
- Vesna Radojevic
- Department of Biomedicine University Hospital Basel and the Clinic for Otorhinolaryngology, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland
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Somatostatin contributes to in vivo gamma oscillation modulation and odor discrimination in the olfactory bulb. J Neurosci 2010; 30:870-5. [PMID: 20089895 DOI: 10.1523/jneurosci.4958-09.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuropeptides are systematically encountered in local interneurons, but their functional contribution in neural networks is poorly documented. In the mouse main olfactory bulb (MOB), somatostatin is mainly concentrated in local GABAergic interneurons restricted to the external plexiform layer (EPL). Immunohistochemical experiments revealed that the sst2 receptor, the major somatostatin receptor subtype in the telencephalon, is expressed by mitral cells, the MOB principal cells. As odor-activated mitral cells synchronize and generate gamma oscillations of the local field potentials, we investigated whether pharmacological manipulations of sst2 receptors could influence these oscillations in freely behaving mice. In wild-type, but not in sst2 knock-out mice, gamma oscillation power decreased lastingly after intrabulbar injection of an sst2-selective antagonist (BIM-23627), while sst2-selective agonists (octreotide and L-779976) durably increased it. Sst2-mediated oscillation changes were correlated with modifications of the dendrodendritic synaptic transmission between mitral and granule cells. Finally, bilateral injections of BIM-23627 and octreotide respectively decreased and increased odor discrimination performances. Together, these results suggest that endogenous somatostatin, presumably released from EPL interneurons, affects gamma oscillations through the dendrodendritic reciprocal synapse and contributes to olfactory processing. This provides the first direct correlation between synaptic, oscillatory, and perceptual effects induced by an intrinsic neuromodulator.
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