| 1. |
- Vieillard, Jennifer, et al.
(författare)
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Adult spinal Dmrt3 neurons receive direct somatosensory inputs from ipsi- and contralateral primary afferents and from brainstem motor nuclei
- 2023
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Ingår i: Journal of Comparative Neurology. - : John Wiley & Sons. - 0021-9967 .- 1096-9861. ; 531:1, s. 5-24
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Tidskriftsartikel (refereegranskat)abstract
- In the spinal cord, sensory-motor circuits controlling motor activity are situated in the dorso-ventral interface. The neurons identified by the expression of the transcription factor Doublesex and mab-3 related transcription factor 3 (Dmrt3) have previously been associated with the coordination of locomotion in horses (Equus caballus, Linnaeus, 1758), mice (Mus musculus, Linnaeus, 1758), and zebrafish (Danio rerio, F. Hamilton, 1822). Based on earlier studies, we hypothesized that, in mice, these neurons may be positioned to receive sensory and central inputs to relay processed commands to motor neurons. Thus, we investigated the presynaptic inputs to spinal Dmrt3 neurons using monosynaptic retrograde replication-deficient rabies tracing. The analysis showed that lumbar Dmrt3 neurons receive inputs from intrasegmental neurons, and intersegmental neurons from the cervical, thoracic, and sacral segments. Some of these neurons belong to the excitatory V2a interneurons and to plausible Renshaw cells, defined by the expression of Chx10 and calbindin, respectively. We also found that proprioceptive primary sensory neurons of type Ia2, Ia3, and Ib, defined by the expression of calbindin, calretinin, and Brn3c, respectively, provide presynaptic inputs to spinal Dmrt3 neurons. In addition, we demonstrated that Dmrt3 neurons receive inputs from brain areas involved in motor regulation, including the red nucleus, primary sensory-motor cortex, and pontine nuclei. In conclusion, adult spinal Dmrt3 neurons receive inputs from motor-related brain areas as well as proprioceptive primary sensory neurons and have been shown to connect directly to motor neurons. Dmrt3 neurons are thus positioned to provide sensory-motor control and their connectivity is suggestive of the classical reflex pathways present in the spinal cord.
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| 2. |
- Freitag, Fabio Batista, et al.
(författare)
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Spinal gastrin releasing peptide receptor expressing interneurons are controlled by local phasic and tonic inhibition
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Dorsal horn gastrin-releasing peptide receptor (GRPR) neurons have a central role in itch transmission. Itch signaling has been suggested to be controlled by an inhibitory network in the spinal dorsal horn, as increased scratching behavior can be induced by pharmacological disinhibition or ablation of inhibitory interneurons, but the direct influence of the inhibitory tone on the GRPR neurons in the itch pathway have not been explored. Here we have investigated spinal GRPR neurons through in vitro and bioinformatical analysis. Electrophysiological recordings revealed that GRPR neurons receive local spontaneous excitatory inputs transmitted by glutamate and inhibitory inputs by glycine and GABA, which were transmitted either by separate glycinergic and GABAergic synapses or by glycine and GABA co-releasing synapses. Additionally, all GRPR neurons received both glycine- and GABA-induced tonic currents. The findings show a complex inhibitory network, composed of synaptic and tonic currents that gates the excitability of GRPR neurons, which provides direct evidence for the existence of an inhibitory tone controlling spontaneous discharge in an itch-related neuronal network in the spinal cord. Finally, calcium imaging revealed increased levels of neuronal activity in Grpr-Cre neurons upon application of somatostatin, which provides direct in vitro evidence for disinhibition of these dorsal horn interneurons.
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| 3. |
- Haring, Martin, et al.
(författare)
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Neuronal atlas of the dorsal horn defines its architecture and links sensory input to transcriptional cell types
- 2018
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Ingår i: Nature Neuroscience. - : NATURE PUBLISHING GROUP. - 1097-6256 .- 1546-1726. ; 21:6, s. 869-880
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Tidskriftsartikel (refereegranskat)abstract
- The dorsal horn of the spinal cord is critical to processing distinct modalities of noxious and innocuous sensation, but little is known of the neuronal subtypes involved, hampering efforts to deduce principles governing somatic sensation. Here we used single-cell RNA sequencing to classify sensory neurons in the mouse dorsal horn. We identified 15 inhibitory and 15 excitatory molecular subtypes of neurons, equaling the complexity in cerebral cortex. Validating our classification scheme in vivo and matching cell types to anatomy of the dorsal horn by spatial transcriptomics reveals laminar enrichment for each of the cell types. Neuron types, when combined, define a multilayered organization with like neurons layered together. Employing our scheme, we find that heat and cold stimuli activate discrete sets of both excitatory and inhibitory neuron types. This work provides a systematic and comprehensive molecular classification of spinal cord sensory neurons, enabling functional interrogation of sensory processing.
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| 4. |
- Iglesias Gonzalez, Ana Belen, et al.
(författare)
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Single cell transcriptomic analysis of spinal Dmrt3 neurons in zebrafish and mouse identifies distinct subtypes and reveal novel subpopulations within the dI6 domain
- 2021
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Ingår i: Frontiers in Cellular Neuroscience. - : Frontiers Media S.A.. - 1662-5102. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- The spinal locomotor network is frequently used for studies into how neuronal circuitsare formed and how cellular activity shape behavioral patterns. A population of dI6interneurons, marked by the Doublesex and mab-3 related transcription factor 3(Dmrt3), has been shown to participate in the coordination of locomotion and gaitsin horses, mice and zebrafish. Analyses of Dmrt3 neurons based on morphology,functionality and the expression of transcription factors have identified differentsubtypes. Here we analyzed the transcriptomes of individual cells belonging to theDmrt3 lineage from zebrafish and mice to unravel the molecular code that underliestheir subfunctionalization. Indeed, clustering of Dmrt3 neurons based on their geneexpression verified known subtypes and revealed novel populations expressing uniquemarkers. Differences in birth order, differential expression of axon guidance genes,neurotransmitters, and their receptors, as well as genes affecting electrophysiologicalproperties, were identified as factors likely underlying diversity. In addition, thecomparison between fish and mice populations offers insights into the evolutionarydriven subspecialization concomitant with the emergence of limbed locomotion
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| 5. |
- Jakobsson, Jon E. T., 1988-
(författare)
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Deciphering neural networks in the somatosensory system using single-cell transcriptomics and rabies tracing
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Itch has evolved to protect us from malicious parasites keen to suck our blood or lay their eggs in our skin. We can detect both the movement of these parasites and the toxins they introduce with specialized neurons called pruriceptors. When we feel an itch, we get a desire to scratch it. Scratching an itch eases the itch sensation, and this is thought to be regulated by neuronal circuits in the spinal cord. This reactive aspect of itch makes is an interesting system to study as it involves both sensory and motor circuitry. The spinal cord hosts a vast number of different neuronal cell types, and better understanding of these are needed to efficiently delineate the circuitry between them. To find these cell types, we sequence the transcriptome of thousands of individual neurons in the dorsal horn of the spinal cord and identified 15 excitatory and 15 inhibitory neuronal populations (Paper I). Furthermore, we found that cell types expressing neuropeptide Y (NPY) contributed to the inhibition of chemically induced itch via the NPY receptor 2 (Paper II) and inhibition of somatostatin-induced itch via NPY receptor 1 (Paper III). We are currently mapping the neurons presynaptic to the NPY neurons using a Npy-Cre mouse line combined with monosynaptic rabies tracing and find inputs from the dorsal root ganglions, the spinal cord, and the brain (Paper IV). To help decipher circuit connectivity, we developed a method that links cell types expressing matching ligand and receptor pairs in single cell RNA-sequencing (scRNA-seq) datasets (Paper V). We furthermore used scRNA-seq to identify differences and similarities of locomotor circuitry related cells expressing doublesex and mab-3 related transcription factor 3 in zebrafish and mouse (Paper VI).In this thesis, we used a combination of powerful and novel tools to investigate questions that were previously difficult to address. It is my belief that spatial transcriptomics, now poised with the knowledge gained from scRNA-seq, will transform how we think about cell types in the central nervous system, since the location of a neuron is critical for its role in a circuit.
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| 6. |
- Jakobsson, Jon E T, et al.
(författare)
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Neuropeptide Y-Cre neurons in the spinal cord receive complex inputs from primary afferent, spinal interneurons and supraspinal regions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Both pain and itch signalling are modulated at the level of the spinal cord. Several spinal cord interneuron populations have been identified to play a crucial role in the canonical modality specific pathways, such as the gastrin releasing peptide receptor-expressing neurons in itch, and the neurokinin receptor 1-expressing projection neurons in pain signalling. NPY has recently been shown to inhibit chemically-, mechanically-, and morphine-induced itch. However, the input to the NPY-expressing interneurons in the spinal cord is relatively unknown, where primary afferent has been implicated, but not intra or supra spinal connections. To detect these pathways, we utilize Cre-dependent monosynaptic rabies tracing to label presynaptic neurons. We show that the NPY-expressing cells are located in most spinal cord laminae and receive input from the primary afferents, local spinal interneurons and brain regions, such as the primary motor cortex. These findings highlight the complex and likely multifaceted role NPY plays in sensory and motor modulation.
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| 7. |
- Jakobsson, Jon E. T., et al.
(författare)
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Neuropeptide Y in itch regulation
- 2019
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Ingår i: Neuropeptides. - : Elsevier BV. - 0143-4179 .- 1532-2785. ; 78
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Forskningsöversikt (refereegranskat)abstract
- Itch is a somatosensory sensation that informs the organism about the presence of potentially harmful substances or parasites, and initiates scratching to remove the threat. Itch-inducing (pruritogenic) substances activate primary afferent neurons in the skin through interactions with specific receptors that converts the stimulus into an electrical signal. These signals are conveyed to the dorsal horn of the spinal cord through the release of neurotransmitters such as natriuretic polypeptide b and somatostatin, leading to an integrated response within a complex spinal inteneuronal network. A large sub-population of somatostatin-expressing spinal interneurons also carry the Neuropeptide Y (NPY) Y1 receptor, indicating that NPY and somatostatin partly regulate the same neuronal pathway. This review focuses on recent findings regarding the role of the NPY/Y1 and somatostatin/SST2A receptor in itch, and also presents data integrating the two neurotransmitter systems.
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| 8. |
- Jakobsson, Jon E. T., et al.
(författare)
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scConnect : a method for exploratory analysis of cell–cell communication based on single-cell RNA-sequencing data
- 2021
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Ingår i: Bioinformatics. - : Oxford University Press. - 1367-4803 .- 1367-4811 .- 1460-2059. ; 37:20, s. 3501-3508
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Tidskriftsartikel (refereegranskat)abstract
- MotivationCell to cell communication is critical for all multicellular organisms, and single-cell sequencing facilitates the construction of full connectivity graphs between cell types in tissues. Such complex data structures demand novel analysis methods and tools for exploratory analysis.ResultsWe propose a method to predict the putative ligand–receptor interactions between cell types from single-cell RNA-sequencing data. This is achieved by inferring and incorporating interactions in a multi-directional graph, thereby enabling contextual exploratory analysis. We demonstrate that our approach can detect common and specific interactions between cell types in mouse brain and human tumors, and that these interactions fit with expected outcomes. These interactions also include predictions made with molecular ligands integrating information from several types of genes necessary for ligand production and transport. Our implementation is general and can be appended to any transcriptome analysis pipeline to provide unbiased hypothesis generation regarding ligand to receptor interactions between cell populations or for network analysis in silico.Availability and implementationscConnect is open source and available as a Python package at https://github.com/JonETJakobsson/scConnect. scConnect is directly compatible with Scanpy scRNA-sequencing pipelines.
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| 9. |
- Ma, Haisha, et al.
(författare)
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The Neuropeptide Y Y-2 Receptor Is Coexpressed with Nppb in Primary Afferent Neurons and Y-2 Activation Reduces Histaminergic and IL-31-Induced Itch
- 2020
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Ingår i: Journal of Pharmacology and Experimental Therapeutics. - : AMER SOC PHARMACOLOGY EXPERIMENTAL THERAPEUTICS. - 0022-3565 .- 1521-0103. ; 372:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- Itch stimuli are detected by specialized primary afferents that convey the signal to the spinal cord, but how itch transmission is regulated is still not completely known. Here, we investigated the roles of the neuropeptide Y (NPY)/Y-2 receptor system on scratch behavior. The inhibitory Y-2 receptor is expressed on mouse primary afferents, and intrathecal administration of the Y-2 agonist peptide YY (PYY)(3-36) reduced scratch episode frequency and duration induced by compound 48/80, an effect that could be reversed by intrathecal preadministration of the Y-2 antagonist BIIE0246. Also, scratch episode duration induced by histamine could be reduced by PYY3-36. In contrast, scratch behavior induced by alpha-methyl-5HT, protease-activated receptor-2-activating peptide SLIGRL, chloroquine, topical dust mite extract, or mechanical itch induced by von Frey filaments was unaffected by stimulation of Y2. Primary afferent neurons expressing the Npy2r gene were found to coexpress itch-associated markers such as natriuretic peptide precursor b, oncostatin M receptor, and interleukin (IL) 31 receptor A. Accordingly, intrathecal PYY3-36 reduced the scratch behavior induced by IL-31. Our findings imply that the NPY/Y-2 system reduces histaminergic and IL-31-associated itch through presynaptic inhibition of a subpopulation of itch-associated primary afferents. SIGNIFICANCE STATEMENT The spinal neuropeptide Y system dampens scratching behavior induced by histaminergic compounds and interleukin 31, a cytokine involved in atopic dermatitis, through interactions with the Y-2 receptor. The Y-2 receptor is expressed by primary afferent neurons that are rich in itch-associated neurotransmitters and receptors such as somatostatin, natriuretic peptide precursor b, and interleukin 31 receptors.
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| 10. |
- Spencer, Nick J., et al.
(författare)
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CGRP alpha within the Trpv1-Cre population contributes to visceral nociception
- 2018
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Ingår i: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : AMER PHYSIOLOGICAL SOC. - 0193-1857 .- 1522-1547. ; 314:2, s. G188-G200
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Tidskriftsartikel (refereegranskat)abstract
- The role of calcitonin gene-related peptide (CGRP) in visceral and somatic nociception is incompletely understood. CGRP alpha is highly expressed in sensory neurons of dorsal root ganglia and particularly in neurons that also express the transient receptor potential cation channel subfamily V member 1 (Trpv1). Therefore, we investigated changes in visceral and somatic nociception following deletion of CGRP alpha from the Trpv1-Cre population using the Cre/lox system. In control mice, acetic acid injection (0.6%, ip) caused significant immobility (time stationary), an established indicator of visceral pain. In CGRP alpha-mCherry(lx/lx); Trpv1-Cre mice, the duration of immobility was significantly less than controls, and the distance CGRP alpha-mCherry(lx/lx); Trpv1-Cre mice traveled over 20 min following acetic acid was significantly greater than controls. However, following acetic acid injection, there was no difference between genotypes in the writhing reflex, number of abdominal licks, or forepaw wipes of the cheek. CGRP alpha-mCherry(lx/lx); Trpv1-Cre mice developed more pronounced inflammation-induced heat hypersensitivity above baseline values compared with controls. However, analyses of noxious acute heat or cold transmission revealed no difference between genotypes. Also, odor avoidance test, odor preference test, and buried food test for olfaction revealed no differences between genotypes. Our findings suggest that CGRP alpha-mediated transmission within the Trpv1-Cre population plays a significant role in visceral nociceptive pathways underlying voluntary movement. Monitoring changes in movement over time is a sensitive parameter to identify differences in visceral nociception, compared with writhing reflexes, abdominal licks, or forepaw wipes of the cheek that were unaffected by deletion of CGRP alpha- from Trpv1-Cre population and likely utilize different mechanisms. NEW & NOTEWORTHY The neuropeptide calcitonin gene-related peptide (CGRP) is highly colocalized with transient receptor potential cation channel subfamily V member 1 (TRPV1)-expressing primary afferent neurons, but the functional role of CGRP alpha specifically in these neurons is unknown in pain processing from visceral and somatic afferents. We used cre-lox recombination to conditionally delete CGRP alpha from TRPV1-expressing neurons in mice. We show that CGRP alpha from within TRPV1-cre population plays an important role in visceral nociception but less so in somatic nociception.
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