scholarly journals Single-axon-resolution intravital imaging reveals a rapid onset form of Wallerian degeneration in the adult neocortex

2018 ◽  
Author(s):  
A.J. Canty ◽  
J.S. Jackson ◽  
L. Huang ◽  
A. Trabalza ◽  
C. Bass ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Wallerian Degeneration ◽  
Rapid Onset ◽  
Therapeutic Window ◽  
Mammalian Brain ◽  
Axon Degeneration ◽  
Single Axon ◽  
Threshold Length ◽  
Longitudinal Imaging

ABSTRACTDespite the widespread occurrence of axon degeneration in the injured and diseased nervous system, the mechanisms of the degenerative process remain incompletely understood. In particular, the factors that regulate how individual axons degenerate within their native environment in the mammalian brain are unknown. Longitudinal imaging of >120 individually injured cortical axons revealed a threshold length below which injured axons undergo a rapid-onset form of Wallerian degeneration (ROWD). ROWD consistently starts 10 times earlier and is executed 4 times slower than classic Wallerian degeneration (WD). ROWD is dependent on synaptic density, unlike WD, but is independent of axon complexity. Finally, we provide both pharmacological and genetic evidence that a Nicotinamide Adenine Dinucleotide (NAD+)-dependent pathway controls cortical axon ROWD independent of transcription in the damaged neurons. Thus, our data redefine the therapeutic window for intervention to maintain neurological function in injured cortical neurons, and support the use of in vivo optical imaging to gain unique insights into the mechanisms of axon degeneration in the brain.

scholarly journals In vivo imaging of injured cortical axons reveals a rapid onset form of Wallerian degeneration

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Alison Jane Canty ◽  
Johanna Sara Jackson ◽  
Lieven Huang ◽  
Antonio Trabalza ◽  
Cher Bass ◽  
...  
Keyword(s):  
Nervous System ◽  
Wallerian Degeneration ◽  
Molecular Mechanisms ◽  
Rapid Onset ◽  
Spatiotemporal Dynamics ◽  
Myelinated Fibre ◽  
Mammalian Brain ◽  
Axon Loss ◽  
Synaptic Mechanisms

Abstract Background Despite the widespread occurrence of axon and synaptic loss in the injured and diseased nervous system, the cellular and molecular mechanisms of these key degenerative processes remain incompletely understood. Wallerian degeneration (WD) is a tightly regulated form of axon loss after injury, which has been intensively studied in large myelinated fibre tracts of the spinal cord, optic nerve and peripheral nervous system (PNS). Fewer studies, however, have focused on WD in the complex neuronal circuits of the mammalian brain, and these were mainly based on conventional endpoint histological methods. Post-mortem analysis, however, cannot capture the exact sequence of events nor can it evaluate the influence of elaborated arborisation and synaptic architecture on the degeneration process, due to the non-synchronous and variable nature of WD across individual axons. Results To gain a comprehensive picture of the spatiotemporal dynamics and synaptic mechanisms of WD in the nervous system, we identify the factors that regulate WD within the mouse cerebral cortex. We combined single-axon-resolution multiphoton imaging with laser microsurgery through a cranial window and a fluorescent membrane reporter. Longitudinal imaging of > 150 individually injured excitatory cortical axons revealed a threshold length below which injured axons consistently underwent a rapid-onset form of WD (roWD). roWD started on average 20 times earlier and was executed 3 times slower than WD described in other regions of the nervous system. Cortical axon WD and roWD were dependent on synaptic density, but independent of axon complexity. Finally, pharmacological and genetic manipulations showed that a nicotinamide adenine dinucleotide (NAD+)-dependent pathway could delay cortical roWD independent of transcription in the damaged neurons, demonstrating further conservation of the molecular mechanisms controlling WD in different areas of the mammalian nervous system. Conclusions Our data illustrate how in vivo time-lapse imaging can provide new insights into the spatiotemporal dynamics and synaptic mechanisms of axon loss and assess therapeutic interventions in the injured mammalian brain.

scholarly journals Light-Sheet Microscopy in Neuroscience

2019 ◽  
Vol 42 (1) ◽  
pp. 295-313 ◽  
Author(s):  
Elizabeth M.C. Hillman ◽  
Venkatakaushik Voleti ◽  
Wenze Li ◽  
Hang Yu
Keyword(s):  
High Speed ◽  
Light Sheet ◽  
Mammalian Brain ◽  
Diverse Range ◽  
Volumetric Imaging ◽  
Two Photon Microscopy ◽  
Light Sheet Microscopy ◽  
Noise Benefits ◽  
Longitudinal Imaging

Light-sheet microscopy is an imaging approach that offers unique advantages for a diverse range of neuroscience applications. Unlike point-scanning techniques such as confocal and two-photon microscopy, light-sheet microscopes illuminate an entire plane of tissue, while imaging this plane onto a camera. Although early implementations of light sheet were optimized for longitudinal imaging of embryonic development in small specimens, emerging implementations are capable of capturing light-sheet images in freely moving, unconstrained specimens and even the intact in vivo mammalian brain. Meanwhile, the unique photobleaching and signal-to-noise benefits afforded by light-sheet microscopy's parallelized detection deliver the ability to perform volumetric imaging at much higher speeds than can be achieved using point scanning. This review describes the basic principles and evolution of light-sheet microscopy, followed by perspectives on emerging applications and opportunities for both imaging large, cleared, and expanded neural tissues and high-speed, functional imaging in vivo.

scholarly journals A neuroprotective agent that inactivates prodegenerative TrkA and preserves mitochondria

2017 ◽  
Vol 216 (11) ◽  
pp. 3655-3675 ◽  
Author(s):  
Konstantin Feinberg ◽  
Adelaida Kolaj ◽  
Chen Wu ◽  
Natalie Grinshtein ◽  
Jonathan R. Krieger ◽  
...  
Keyword(s):  
Wallerian Degeneration ◽  
Axonal Degeneration ◽  
Kinase Inhibitor ◽  
Sympathetic Neurons ◽  
Energy Deficit ◽  
Axon Degeneration ◽  
Therapeutic Drug ◽  
Early Event ◽  
Sod1 Mutant

Axon degeneration is an early event and pathological in neurodegenerative conditions and nerve injuries. To discover agents that suppress neuronal death and axonal degeneration, we performed drug screens on primary rodent neurons and identified the pan-kinase inhibitor foretinib, which potently rescued sympathetic, sensory, and motor wt and SOD1 mutant neurons from trophic factor withdrawal-induced degeneration. By using primary sympathetic neurons grown in mass cultures and Campenot chambers, we show that foretinib protected neurons by suppressing both known degenerative pathways and a new pathway involving unliganded TrkA and transcriptional regulation of the proapoptotic BH3 family members BimEL, Harakiri,and Puma, culminating in preservation of mitochondria in the degenerative setting. Foretinib delayed chemotherapy-induced and Wallerian axonal degeneration in culture by preventing axotomy-induced local energy deficit and preserving mitochondria, and peripheral Wallerian degeneration in vivo. These findings identify a new axon degeneration pathway and a potentially clinically useful therapeutic drug.

scholarly journals In vivo modeling of human neuron dynamics and Down syndrome

Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. eaau1810 ◽  
Author(s):  
Raquel Real ◽  
Manuel Peter ◽  
Antonio Trabalza ◽  
Shabana Khan ◽  
Mark A. Smith ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Cortical Neurons ◽  
Synapse Formation ◽  
Induced Pluripotent Stem Cell ◽  
Patient Specific ◽  
Human Stem Cells ◽  
Population Activity ◽  
Human Neurons ◽  
Longitudinal Imaging

Harnessing the potential of human stem cells for modeling the physiology and diseases of cortical circuitry requires monitoring cellular dynamics in vivo. We show that human induced pluripotent stem cell (iPSC)–derived cortical neurons transplanted into the adult mouse cortex consistently organized into large (up to ~100 mm3) vascularized neuron-glia territories with complex cytoarchitecture. Longitudinal imaging of >4000 grafted developing human neurons revealed that neuronal arbors refined via branch-specific retraction; human synaptic networks substantially restructured over 4 months, with balanced rates of synapse formation and elimination; and oscillatory population activity mirrored the patterns of fetal neural networks. Lastly, we found increased synaptic stability and reduced oscillations in transplants from two individuals with Down syndrome, demonstrating the potential of in vivo imaging in human tissue grafts for patient-specific modeling of cortical development, physiology, and pathogenesis.

Platelet Aggregation in Diabetes Mellitus and the Effect of Insulin in Vivo on Aggregation

1972 ◽  
Vol 27 (01) ◽  
pp. 114-120 ◽  
Author(s):  
A. A Hassanein ◽  
Th. A El-Garf ◽  
Z El-Baz
Keyword(s):  
Platelet Aggregation ◽  
Rapid Onset ◽  
Control Group ◽  
Diabetic Patients ◽  
Fasting State ◽  
Clotting Time ◽  
Cholesterol Levels ◽  
Platelet Disaggregation ◽  
Aggregation And Disaggregation

SummaryADP-induced platelet aggregation and calcium-induced platelet aggregation tests were studied in 14 diabetic patients in the fasting state and half an hour after an intravenous injection of 0.1 unit insulin/kg body weight. Platelet disaggregation was significantly diminished as compared to a normal control group, and their results were negatively correlated with the corresponding serum cholesterol levels. Insulin caused significant diminution in the ADP-induced platelet aggregation as a result of rapid onset of aggregation and disaggregation. There was also a significant increase in platelet disaggregation. In the calcium-induced platelet aggregation test, there was a significant shortening of the aggregation time, its duration, and the clotting time. The optical density fall due to platelet aggregation showed a significant increase. Insulin may have a role in correcting platelet disaggregation possibly through improvement in the intracellular enzymatic activity.

Highly Potent rhenium(I) Tricarbonyl Complexes with Dual Anticancer and Anti-Angiogenic Activity Against Colorectal Carcinoma

2020 ◽  
Author(s):  
Joachim Delasoie ◽  
Aleksandar Pavic ◽  
Noémie Voutier ◽  
Sandra Vojnovic ◽  
Aurélien Crochet ◽  
...  
Keyword(s):  
Colorectal Carcinoma ◽  
Anticancer Drugs ◽  
Xenograft Model ◽  
Therapeutic Window ◽  
Low Doses ◽  
Sunitinib Malate ◽  
Angiogenic Activity ◽  
Antimetastatic Activity ◽  
Clinical Drugs

Synthesized and characterized a series of rhenium(I) trycarbonyl-based complexes with increased lipophilicity. Two of these novel compounds were discovered to possess remarkable anticancer, anti-angiogenic and antimetastatic activity <i>in vivo</i> (zebrafish-human CRC xenograft model), being effective at very low doses (1-3 µM). At doses as high as 250 µM the complexes did not provoke toxicity issues encountered in clinical anticancer drugs (cardio-, hepato-, and myelotoxicity). The two compounds exceed the antiproliferative and anti-angiogenic potency of clinical drugs cisplatin and sunitinib-malate, and display a large therapeutic window.

scholarly journals Drosophila Preparation and Longitudinal Imaging of Heart Function In Vivo Using Optical Coherence Microscopy (OCM)

10.3791/55002 ◽  
2016 ◽  
Author(s):  
Jing Men ◽  
Jason Jerwick ◽  
Penghe Wu ◽  
Mingming Chen ◽  
Aneesh Alex ◽  
...  
Keyword(s):  
Heart Function ◽  
Optical Coherence ◽  
Optical Coherence Microscopy ◽  
Longitudinal Imaging

scholarly journals TRAF3 mediates neuronal apoptosis in early brain injury following subarachnoid hemorrhage via targeting TAK1-dependent MAPKs and NF-κB pathways

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yan Zhou ◽  
Tao Tao ◽  
Guangjie Liu ◽  
Xuan Gao ◽  
Yongyue Gao ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Brain Injury ◽  
Therapeutic Target ◽  
Cortical Neurons ◽  
Neuronal Apoptosis ◽  
Early Brain Injury ◽  
Neurological Deficits ◽  
Human Brain Tissue

AbstractNeuronal apoptosis has an important role in early brain injury (EBI) following subarachnoid hemorrhage (SAH). TRAF3 was reported as a promising therapeutic target for stroke management, which covered several neuronal apoptosis signaling cascades. Hence, the present study is aimed to determine whether downregulation of TRAF3 could be neuroprotective in SAH-induced EBI. An in vivo SAH model in mice was established by endovascular perforation. Meanwhile, primary cultured cortical neurons of mice treated with oxygen hemoglobin were applied to mimic SAH in vitro. Our results demonstrated that TRAF3 protein expression increased and expressed in neurons both in vivo and in vitro SAH models. TRAF3 siRNA reversed neuronal loss and improved neurological deficits in SAH mice, and reduced cell death in SAH primary neurons. Mechanistically, we found that TRAF3 directly binds to TAK1 and potentiates phosphorylation and activation of TAK1, which further enhances the activation of NF-κB and MAPKs pathways to induce neuronal apoptosis. Importantly, TRAF3 expression was elevated following SAH in human brain tissue and was mainly expressed in neurons. Taken together, our study demonstrates that TRAF3 is an upstream regulator of MAPKs and NF-κB pathways in SAH-induced EBI via its interaction with and activation of TAK1. Furthermore, the TRAF3 may serve as a novel therapeutic target in SAH-induced EBI.

Sign in / Sign up

Export Citation Format

Share Document