scholarly journals Imaging activation of peptidergic spinal afferent varicosities within visceral organs using novel CGRPα-mCherry reporter mice

2016 ◽  
Vol 311 (5) ◽  
pp. G880-G894 ◽  
Author(s):  
Nick J. Spencer ◽  
Julian Sorensen ◽  
Lee Travis ◽  
Lukasz Wiklendt ◽  
Marcello Costa ◽  
...  
Keyword(s):  
Action Potentials ◽  
Visceral Pain ◽  
Sensory Transduction ◽  
Calcium Transients ◽  
Sensory Stimuli ◽  
Myenteric Neurons ◽  
Visceral Organs ◽  
Major Class ◽  
Reporter Mice ◽  
Spinal Afferents

In vertebrates, visceral pain from internal organs is detected by spinal afferents, whose cell bodies lie in dorsal root ganglia (DRG). Until now, all recordings from spinal afferents have been restricted to recording transmission of action potentials along axons, or from cell bodies lying outside their target organ, which is not where sensory transduction occurs. Our aim was to record directly from a major class of spinal afferent within visceral organs, where transduction of sensory stimuli into action potentials occurs. Using novel calcitonin gene-related peptide (CGRP)α reporter mice, DRG neurons expressed mCherry, including nerve axons within viscera. In colon, a minority of total CGRP immunoreactivity was attributed CGRPα. In isolated unstretched colon, calcium imaging from CGRPα-expressing varicose axons did not detect resolvable calcium transients. However, noxious levels of maintained circumferential stretch to the colon induced repetitive calcium transients simultaneously in multiple neighboring varicosities along single mCherry-expressing axons. Discrete varicosities could generate unitary calcium transients independently of neighboring varicosities. However, axons expressing mCherry only generated coordinated calcium transients when accompanied by simultaneous activation of multiple varicosities along that axon. Simultaneous imaging from different classes of myenteric neurons at the same time as mCherry-expressing axons revealed coordinated calcium transients in multiple myenteric neurons, independent of activity in mCherry-expressing axons. CGRPα-expressing axon terminals preferentially responded to heat, capsaicin, and low pH. We show that direct recordings can be made from the major class of peptidergic spinal afferent that contributes to visceral nociception. This approach can provide powerful insights into transduction of stimuli in viscera.

scholarly journals Unique molecular characteristics of visceral afferents arising from different levels of the neuraxis: location of afferent somata predicts function and stimulus detection modalities

2020 ◽  
Author(s):  
Kimberly A. Meerschaert ◽  
Peter C. Adelman ◽  
Robert L. Friedman ◽  
Kathryn M. Albers ◽  
H. R. Koerber ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Visceral Pain ◽  
Visceral Afferents ◽  
Molecular Characteristics ◽  
Homeostatic Regulation ◽  
Visceral Organs ◽  
Nodose Ganglia ◽  
Stimulus Detection ◽  
Bladder Afferents ◽  
Spinal Afferents

AbstractVisceral organs receive neural innervation from sensory ganglia located adjacent to multiple levels of the brainstem and spinal cord. Here we examined whether molecular profiling could be used to identify functional clusters of colon afferents from thoracolumbar (TL), lumbosacral (LS), and nodose ganglia (NG) in the mouse. Profiling of TL and LS bladder afferents was also done. Visceral afferents were back-labeled using retrograde tracers injected into proximal and distal regions of colon or bladder, followed by single cell RT-qPCR and analysis via an automated hierarchical clustering method. Genes were chosen for assay (32 for bladder; 48 for colon) based on their established role in stimulus detection, regulation of sensitivity/function or neuroimmune interaction. A total of 132 colon afferents (from NG, TL and LS) and 128 bladder afferents (from TL and LS) were analyzed. Retrograde labeling from the colon showed NG and TL afferents innervate proximal and distal regions of the colon whereas 98% of LS afferents only project to distal regions. There were clusters of colon and bladder afferents, defined by mRNA profiling, that localized to either TL or LS ganglia. Mixed TL/LS clustering also was found. In addition, transcriptionally, NG colon afferents were almost completely segregated from colon DRG (TL or LS) neurons. These results indicate that populations of primary visceral afferents are functionally “tuned” to detect and interact with the internal environment and that information from all levels is integrated at higher (CNS) levels, not only for regulation of homeostatic functions, but for conscious visceral sensations including pain.Significance StatementVisceral organs are innervated by sensory neurons whose cell bodies are located in multiple ganglia associated with the brainstem and spinal cord. For the colon, this overlapping innervation is proposed to facilitate visceral sensation and homeostasis, where sensation and pain is mediated by spinal afferents and fear and anxiety (the affective aspects of visceral pain) are the domain of nodose afferents. Transcriptomic analysis performed here reveals that genes implicated in both homeostatic regulation and pain are found in afferents across all ganglia types, suggesting that conscious sensation and homeostatic regulation is the result of convergence, and not segregation, of sensory input.

scholarly journals Tetrodotoxin: A New Strategy to Treat Visceral Pain?

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 496
Author(s):  
Ana Campos-Ríos ◽  
Lola Rueda-Ruzafa ◽  
Salvador Herrera-Pérez ◽  
Paula Rivas-Ramírez ◽  
José Antonio Lamas
Keyword(s):  
Action Potentials ◽  
Channel Blocker ◽  
Visceral Pain ◽  
Visceral Hypersensitivity ◽  
Afferent Neurons ◽  
Sodium Channel Blocker ◽  
Voltage Gated Sodium Channels ◽  
New Strategy ◽  
Specific Receptors

Visceral pain is one of the most common symptoms associated with functional gastrointestinal (GI) disorders. Although the origin of these symptoms has not been clearly defined, the implication of both the central and peripheral nervous systems in visceral hypersensitivity is well established. The role of several pathways in visceral nociception has been explored, as well as the influence of specific receptors on afferent neurons, such as voltage-gated sodium channels (VGSCs). VGSCs initiate action potentials and dysfunction of these channels has recently been associated with painful GI conditions. Current treatments for visceral pain generally involve opioid based drugs, ≠≠which are associated with important side-effects and a loss of effectiveness or tolerance. Hence, efforts have been intensified to find new, more effective and longer-lasting therapies. The implication of VGSCs in visceral hypersensitivity has drawn attention to tetrodotoxin (TTX), a relatively selective sodium channel blocker, as a possible and promising molecule to treat visceral pain and related diseases. As such, here we will review the latest information regarding this toxin that is relevant to the treatment of visceral pain and the possible advantages that it may offer relative to other treatments, alone or in combination.

scholarly journals Helical growth during the phototropic response, avoidance response, and in stiff mutants of Phycomyces blakesleeanus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joseph K. E. Ortega ◽  
Revathi P. Mohan ◽  
Cindy M. Munoz ◽  
Shankar Lalitha Sridhar ◽  
Franck J. Vernerey
Keyword(s):  
Avoidance Response ◽  
Experimental Results ◽  
Sensory Transduction ◽  
Growth Responses ◽  
Phycomyces Blakesleeanus ◽  
Sensory Stimuli ◽  
Phototropic Response ◽  
Biophysical Models ◽  
Helical Growth ◽  
Made In

AbstractThe sporangiophores of Phycomyces blakesleeanus have been used as a model system to study sensory transduction, helical growth, and to establish global biophysical equations for expansive growth of walled cells. More recently, local statistical biophysical models of the cell wall are being constructed to better understand the molecular underpinnings of helical growth and its behavior during the many growth responses of the sporangiophores to sensory stimuli. Previous experimental and theoretical findings guide the development of these local models. Future development requires an investigation of explicit and implicit assumptions made in the prior research. Here, experiments are conducted to test three assumptions made in prior research, that (a) elongation rate, (b) rotation rate, and (c) helical growth steepness, R, of the sporangiophore remain constant during the phototropic response (bending toward unilateral light) and the avoidance response (bending away from solid barriers). The experimental results reveal that all three assumptions are incorrect for the phototropic response and probably incorrect for the avoidance response but the results are less conclusive. Generally, the experimental results indicate that the elongation and rotation rates increase during these responses, as does R, indicating that the helical growth steepness become flatter. The implications of these findings on prior research, the “fibril reorientation and slippage” hypothesis, global biophysical equations, and local statistical biophysical models are discussed.

Abstract 17189: Reprogramming of Fibroblasts Into Cardiac Progenitor Cells Using Crispr Activation System

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Lin Jiang ◽  
Jialiang Liang ◽  
Wei Huang ◽  
Christian Paul ◽  
Yigang Wang
Keyword(s):  
Action Potentials ◽  
Differentiation Potential ◽  
Lineage Differentiation ◽  
Cardiac Action ◽  
Reporter Mice ◽  
Gfp Reporter ◽  
Control Virus ◽  
Cardiac Lineage ◽  
Tail Tip ◽  
Crispr Activation

Background and Objective: CRISPR tools that allow for precise manipulation of individual loci have not been used in generation of i nduced c ardiac p rogenitor c ells ( iCPC s). This study was designed to determine the feasibility and effectiveness of reprogramming fibroblasts into iCPC using CRISPR activation (CRISPRa) system. Methods: Tail-tip fibroblasts (TTFs) were isolated from Nkx2-5 cardiac enhancer GFP reporter mice. A gRNA pool targeting 17 progenitor genes was synthesized and transduced with dCas9-VP64 lentivirus into TTFs ( Fig.1A ). The phenotype of iCPCs was then characterized by immunostaining and FACS of progenitor markers. Finally, the cardiac-lineage differentiation potential of iCPCs was determined by immunostaining and electrophysiological assay under defined induction mediums. Results: iCPCs with GFP expression were formed in TTFs after transduction of CRISPRa targeting Isl1 , Gata4 , Baf60c , Tbx5 and Nkx2-5 (Fig.1B), while GFP was not activated by control virus. Cardiac progenitor markers were activated in iCPCs as shown by immunostaining (Fig.1C). The generation efficiency of Flk1-postive iCPCs induced by CRISPRa was ~60% as showed by FACS. iCPCs can be differentiated into cardiomyocytes as identified by immunostaining of cardiac-specific markers (Fig.1D). The iCPC-derived cardiomyocytes displayed spontaneous beating and showed cardiac action potentials (Fig.1E). Conclusion: The CRISPRa system is an efficient and specific way to generate iCPCs, which could provide a novel source of cells for cardiac regenerative medicine.

scholarly journals Oxaliplatin neurotoxicity of sensory transduction in rat proprioceptors

2011 ◽  
Vol 106 (2) ◽  
pp. 704-709 ◽  
Author(s):  
Katie L. Bullinger ◽  
Paul Nardelli ◽  
Qingbo Wang ◽  
Mark M. Rich ◽  
Timothy C. Cope
Keyword(s):  
Action Potentials ◽  
Muscle Length ◽  
Sensory Transduction ◽  
Muscle Stretch ◽  
Functional Deficits ◽  
Oxaliplatin Treatment ◽  
Sensory Encoding ◽  
Dying Back ◽  
Striking Contrast

Neurotoxic effects of oxaliplatin chemotherapy, including proprioceptive impairments, are debilitating and dose limiting. Here, we sought to determine whether oxaliplatin interrupts normal proprioceptive feedback by impairing sensory transduction of muscle length and force by neurons that are not damaged by dying-back neuropathy. Oxaliplatin was administered over 4 wk to rats in doses that produced systemic changes, e.g., decreased platelets and stunted weight gain, but no significant abnormality in the terminal ends of primary muscle spindle sensory neurons. The absence of neuropathy enabled the determination of whether oxaliplatin caused functional deficits in sensory encoding without the confounding issue of axon death. Rats were anesthetized, and action potentials encoding muscle stretch and contraction were recorded intra-axonally from dorsal roots. In striking contrast with normal proprioceptors, those from oxaliplatin-treated rats typically failed to sustain firing during static muscle stretch. The ability of spindle afferents to sustain and centrally conduct trains of action potentials in response to rapidly repeated transient stimuli, i.e., vibration, demonstrated functional competence of the parent axons. These data provide the first evidence that oxaliplatin causes persistent and selective deficits in sensory transduction that are not due to axon degeneration. Our findings raise the possibility that even those axons that do not degenerate after oxaliplatin treatment may have functional deficits that worsen outcome.

Irritable Bowel Syndrome: Methods, Mechanisms, and Pathophysiology. Methods to assess visceral hypersensitivity in irritable bowel syndrome

2012 ◽  
Vol 303 (2) ◽  
pp. G141-G154 ◽  
Author(s):  
D. Keszthelyi ◽  
F. J. Troost ◽  
A. A. Masclee
Keyword(s):  
Irritable Bowel Syndrome ◽  
Brain Imaging ◽  
Visceral Pain ◽  
Gastrointestinal Disorder ◽  
Visceral Hypersensitivity ◽  
Visceral Perception ◽  
Optimal Method ◽  
Flexor Reflex ◽  
Sensory Stimuli ◽  
Irritable Bowel

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, characterized by recurrent abdominal pain or discomfort in combination with disturbed bowel habits in the absence of identifiable organic cause. Visceral hypersensitivity has emerged as a key hypothesis in explaining the painful symptoms in IBS and has been proposed as a “biological hallmark” for the condition. Current techniques of assessing visceral perception include the computerized barostat using rectal distensions, registering responses induced by sensory stimuli including the flexor reflex and cerebral evoked potentials, as well as brain imaging modalities such as functional magnetic resonance imaging and positron emission tomography. These methods have provided further insight into alterations in pain processing in IBS, although the most optimal method and condition remain to be established. In an attempt to give an overview of these methods, a literature search in the electronic databases PubMed and MEDLINE was executed using the search terms “assessment of visceral pain/visceral nociception/visceral hypersensitivity” and “irritable bowel syndrome.” Both original articles and review articles were considered for data extraction. This review aims to discuss currently used modalities in assessing visceral perception, along with advantages and limitations, and aims also to define future directions for methodological aspects in visceral pain research. Although novel paradigms such as brain imaging and neurophysiological recordings have been introduced in the study of visceral pain, confirmative studies are warranted to establish their robustness and clinical relevance. Therefore, subjective verbal reporting following rectal distension currently remains the best-validated technique in assessing visceral perception in IBS.

scholarly journals In vivo calcium imaging of CA3 pyramidal neuron populations in adult mouse hippocampus

2021 ◽  
Author(s):  
Gwendolin Schoenfeld ◽  
Stefano Carta ◽  
Peter Rupprecht ◽  
Aslı Ayaz ◽  
Fritjof Helmchen
Keyword(s):  
Calcium Imaging ◽  
Action Potentials ◽  
Pyramidal Neurons ◽  
Population Level ◽  
Calcium Transients ◽  
Population Activity ◽  
Brain Functions ◽  
State Dependent ◽  
Multiple Imaging ◽  
Ca3 Pyramidal Neurons

Neuronal population activity in the hippocampal CA3 subfield is implicated in cognitive brain functions such as memory processing and spatial navigation. However, because of its deep location in the brain, the CA3 area has been difficult to target with modern calcium imaging approaches. Here, we achieved chronic two-photon calcium imaging of CA3 pyramidal neurons with the red fluorescent calcium indicator R-CaMP1.07 in anesthetized and awake mice. We characterize CA3 neuronal activity at both the single-cell and population level and assess its stability across multiple imaging days. During both anesthesia and wakefulness, nearly all CA3 pyramidal neurons displayed calcium transients. Most of the calcium transients were consistent with a high incidence of bursts of action potentials, based on calibration measurements using simultaneous juxtacellular recordings and calcium imaging. In awake mice, we found state-dependent differences with striking large and prolonged calcium transients during locomotion. We estimate that trains of >30 action potentials over 3 s underlie these salient events. Their abundance in particular subsets of neurons was relatively stable across days. At the population level, we found that coactivity within the CA3 network was above chance level and that co-active neuron pairs maintained their correlated activity over days. Our results corroborate the notion of state-dependent spatiotemporal activity patterns in the recurrent network of CA3 and demonstrate that at least some features of population activity, namely coactivity of cell pairs and likelihood to engage in prolonged high activity, are maintained over days.

Sign in / Sign up

Export Citation Format

Share Document