Cyclic AMP-Induced Repair of Zebrafish Spinal Circuits

Bhatt, Dimple H.; Otto, Stefanie; Depoister, Brett; Fetcho, Joseph R.

doi:10.1126/science.1098439

Cited by 174 publications

(178 citation statements)

References 32 publications

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“…Single-cell labeling with rhodamine-dextran (3000 molecular weight; Invitrogen) by electroporation was performed essentially as described previously (Bhatt et al, 2004).…”

Section: Methodsmentioning

confidence: 99%

“…We then examined the morphology of CoLo neurons by loading rhodamine-dextran or Alexa Fluor 594 into individual CoLo neurons through electroporation (Bhatt et al, 2004;Kimura et al, 2006) or whole-cell recordings, respectively. We have observed Ͼ100 CoLos, and essentially all of these had the same morphological features throughout the stages examined (2-4 dpf).…”

Section: Tol-056 Enhancer Trap Line Labels a Specific Class Of Commismentioning

confidence: 99%

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Functional Role of a Specialized Class of Spinal Commissural Inhibitory Neurons during Fast Escapes in Zebrafish

Satou¹,

Kimura²,

Kohashi³

et al. 2009

J. Neurosci.

143

157

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In teleost fish, the Mauthner (M) cell, a large reticulospinal neuron in the brainstem, triggers escape behavior. Spinal commissural inhibitory interneurons that are electrotonically excited by the M-axon have been identified, but the behavioral roles of these neurons have not yet been addressed. Here, we studied these neurons, named CoLo (commissural local), in larval zebrafish using an enhancer-trap line in which the entire population of CoLos was visualized by green fluorescent protein. CoLos were present at one cell per hemi-segment. Electrophysiological recordings showed that an M-spike evoked a spike in CoLos via electrotonic transmission and that CoLos made monosynaptic inhibitory connections onto contralateral primary motoneurons, consistent with the results in adult goldfish. We further showed that CoLos were active only during escapes. We examined the behavioral roles of CoLos by investigating escape behaviors in CoLo-ablated larvae. The results showed that the escape behaviors evoked by sound/vibration stimuli were often impaired with a reduced initial bend of the body, indicating that CoLos play important roles in initiating escapes. We obtained several lines of evidence that strongly suggested that the impaired escapes occurred during bilateral activation of the M-cells: in normal larvae, CoLo-mediated inhibitory circuits enable animals to perform escapes even in these occasions by silencing the output of the slightly delayed firing of the second M-cell. This study illustrates (1) a clear example of the behavioral role of a specialized class of interneurons and (2) the capacity of the spinal circuits to filter descending commands and thereby produce the appropriate behavior.

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“…Single-cell labeling with rhodamine-dextran (3000 molecular weight; Invitrogen) by electroporation was performed essentially as described previously (Bhatt et al, 2004).…”

Section: Methodsmentioning

confidence: 99%

Section: Tol-056 Enhancer Trap Line Labels a Specific Class Of Commismentioning

confidence: 99%

Functional Role of a Specialized Class of Spinal Commissural Inhibitory Neurons during Fast Escapes in Zebrafish

Satou¹,

Kimura²,

Kohashi³

et al. 2009

J. Neurosci.

143

157

View full text Add to dashboard Cite

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“…T he ability of neurons in the adult mammalian central nervous system to regenerate their axons after injury is extremely limited, which has been attributed to both extrinsic signals of the inhibitory glial environment (1) as well as intrinsic neuronal factors (2)(3)(4). The discovery of cell-permeable small molecules that modulate axon regrowth can potentiate the development of efficient therapeutic treatments for spinal cord injuries, brain trauma, stroke, and neurodegenerative diseases.…”

Section: Elegans | Chemical Screen | Microfluidicsmentioning

confidence: 99%

Large-scale in vivo femtosecond laser neurosurgery screen reveals small-molecule enhancer of regeneration

Samara

Rohde

Gilleland

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

110

114

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Discovery of molecular mechanisms and chemical compounds that enhance neuronal regeneration can lead to development of therapeutics to combat nervous system injuries and neurodegenerative diseases. By combining high-throughput microfluidics and femtosecond laser microsurgery, we demonstrate for the first time largescale in vivo screens for identification of compounds that affect neurite regeneration. We performed thousands of microsurgeries at single-axon precision in the nematode Caenorhabditis elegans at a rate of 20 seconds per animal. Following surgeries, we exposed the animals to a hand-curated library of approximately one hundred small molecules and identified chemicals that significantly alter neurite regeneration. In particular, we found that the PKC kinase inhibitor staurosporine strongly modulates regeneration in a concentration-and neuronal type-specific manner. Two structurally unrelated PKC inhibitors produce similar effects. We further show that regeneration is significantly enhanced by the PKC activator prostratin. C. elegans | chemical screen | microfluidicsT he ability of neurons in the adult mammalian central nervous system to regenerate their axons after injury is extremely limited, which has been attributed to both extrinsic signals of the inhibitory glial environment (1) as well as intrinsic neuronal factors (2-4). The discovery of cell-permeable small molecules that modulate axon regrowth can potentiate the development of efficient therapeutic treatments for spinal cord injuries, brain trauma, stroke, and neurodegenerative diseases. Identification of such molecules can also provide valuable tools for fundamental investigations of the mechanisms involved in the regeneration process. Currently, small-molecule screens for neuronal regeneration are performed in simple in vitro cell culture systems. Such screens have already revealed large numbers of chemicals that enhance regeneration and/or affect cellular morphogenesis, yet many of these hits still remain untested in vivo. In addition, most in vitro studies do not translate to animal models and also fail to reveal off-target, toxic, or lethal effects. Thus, a thorough investigation of neuronal regeneration mechanisms requires in vivo neuronal injury models.In vivo investigation of neuronal regeneration has been performed mainly in mice and rats. However, their long developmental periods, complicated genetics and biology, and expensive maintenance prevent large-scale studies on these animals. The nematode Caenorhabditis elegans is a simple, well-studied, invertebrate model-organism with a fully mapped neuronal network comprising 302 neurons. Its short developmental cycle, simple and low-cost laboratory maintenance, and genetic amenability make it an ideal model for large-scale screens, rapid identification of the molecular targets of screened compounds, and discovery of novel signaling pathways implicated in regeneration.Until recently however, the small size of C. elegans (∼50 μm in diameter) prevented its use for investigation of neuronal re...

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“…Modern optical techniques have the potential to overcome these limitations (8,13,14). The restricted absorption volume and deep penetration of multiphoton excitation (15) can be used as a tool to dissect single neurites in the brain of adult mice in vivo (16).…”

mentioning

confidence: 99%

In vivo single branch axotomy induces GAP-43–dependent sprouting and synaptic remodeling in cerebellar cortex

Mascaro

Cesare

Sacconi

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

101

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Plasticity in the central nervous system in response to injury is a complex process involving axonal remodeling regulated by specific molecular pathways. Here, we dissected the role of growthassociated protein 43 (GAP-43; also known as neuromodulin and B-50) in axonal structural plasticity by using, as a model, climbing fibers. Single axonal branches were dissected by laser axotomy, avoiding collateral damage to the adjacent dendrite and the formation of a persistent glial scar. Despite the very small denervated area, the injured axons consistently reshape the connectivity with surrounding neurons. At the same time, adult climbing fibers react by sprouting new branches through the intact surroundings. Newly formed branches presented varicosities, suggesting that new axons were more than just exploratory sprouts. Correlative light and electron microscopy reveals that the sprouted branch contains large numbers of vesicles, with varicosities in the close vicinity of Purkinje dendrites. By using an RNA interference approach, we found that downregulating GAP-43 causes a significant increase in the turnover of presynaptic boutons. In addition, silencing hampers the generation of reactive sprouts. Our findings show the requirement of GAP-43 in sustaining synaptic stability and promoting the initiation of axonal regrowth.brain injury | two-photon imaging | neural plasticity | laser nanosurgery

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Cyclic AMP-Induced Repair of Zebrafish Spinal Circuits

Cited by 174 publications

References 32 publications

Functional Role of a Specialized Class of Spinal Commissural Inhibitory Neurons during Fast Escapes in Zebrafish

Functional Role of a Specialized Class of Spinal Commissural Inhibitory Neurons during Fast Escapes in Zebrafish

Large-scale in vivo femtosecond laser neurosurgery screen reveals small-molecule enhancer of regeneration

In vivo single branch axotomy induces GAP-43–dependent sprouting and synaptic remodeling in cerebellar cortex

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