scholarly journals Epicortical Brevetoxin Treatment Promotes Neural Repair and Functional Recovery after Ischemic Stroke

Marine Drugs ◽  
2020 ◽  
Vol 18 (7) ◽  
pp. 374 ◽  
Author(s):  
Erica Sequeira ◽  
Marsha L. Pierce ◽  
Dina Akasheh ◽  
Stacey Sellers ◽  
William H. Gerwick ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Cortical Excitability ◽  
Cortical Layer ◽  
Motor Recovery ◽  
Infarct Zone ◽  
Neural Repair ◽  
Infarct Region ◽  
Stroke Models ◽  
Synapse Density ◽  
Layer V

Emerging literature suggests that after a stroke, the peri-infarct region exhibits dynamic changes in excitability. In rodent stroke models, treatments that enhance excitability in the peri-infarct cerebral cortex promote motor recovery. This increase in cortical excitability and plasticity is opposed by increases in tonic GABAergic inhibition in the peri-infarct zone beginning three days after a stroke in a mouse model. Maintenance of a favorable excitatory–inhibitory balance promoting cerebrocortical excitability could potentially improve recovery. Brevetoxin-2 (PbTx-2) is a voltage-gated sodium channel (VGSC) gating modifier that increases intracellular sodium ([Na+]i), upregulates N-methyl-D-aspartate receptor (NMDAR) channel activity and engages downstream calcium (Ca2+) signaling pathways. In immature cerebrocortical neurons, PbTx-2 promoted neuronal structural plasticity by increasing neurite outgrowth, dendritogenesis and synaptogenesis. We hypothesized that PbTx-2 may promote excitability and structural remodeling in the peri-infarct region, leading to improved functional outcomes following a stroke. We tested this hypothesis using epicortical application of PbTx-2 after a photothrombotic stroke in mice. We show that PbTx-2 enhanced the dendritic arborization and synapse density of cortical layer V pyramidal neurons in the peri-infarct cortex. PbTx-2 also produced a robust improvement of motor recovery. These results suggest a novel pharmacologic approach to mimic activity-dependent recovery from stroke.

scholarly journals Baseline Glutamate Levels Affect Group I and II mGluRs in Layer V Pyramidal Neurons of Rat Sensorimotor Cortex

2003 ◽  
Vol 89 (3) ◽  
pp. 1308-1316 ◽  
Author(s):  
A. E. Bandrowski ◽  
J. R. Huguenard ◽  
D. A. Prince
Keyword(s):  
Metabotropic Glutamate Receptors ◽  
Pyramidal Neurons ◽  
Cortical Excitability ◽  
Brain Slices ◽  
Mean Amplitude ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii ◽  
Layer V

Possible functional roles for glutamate that is detectable at low concentrations in the extracellular space of intact brain and brain slices have not been explored. To determine whether this endogenous glutamate acts on metabotropic glutamate receptors (mGluRs), we obtained whole cell recordings from layer V pyramidal neurons of rat sensorimotor cortical slices. Blockade of mGluRs with (+)-α-amino-4-carboxy-α-methyl-benzeacetic acid (MCPG, a general mGluR antagonist) increased the mean amplitude of spontaneous excitatory postsynaptic currents (sEPSCs), an effect attributable to a selective increase in the occurrence of large amplitude sEPSCs. 2S-2-amino-2-(1S,2S-2-carboxycyclopropyl-1-yl)-3-(xanth-9-yl)propanoic acid (LY341495, a group II antagonist) increased, but R(−)-1-amino-2,3-dihydro-1H-indene-1,5-dicarboxylic acid (AIDA) and (RS)-hexyl-HIBO (group I antagonists) decreased sEPSC amplitude, and (R,S)-α-cyclopropyl-4-phosphonophenylglycine (CPPG, a group III antagonist) did not change it. The change in sEPSCs elicited by MCPG, AIDA, and LY341495 was absent in tetrodotoxin, suggesting that it was action potential-dependent. The increase in sEPSCs persisted in GABA receptor antagonists, indicating that it was not due to effects on inhibitory interneurons. AIDA and ( S)-3,5-dihydroxyphenylglycine (DHPG, a group I agonist) elicited positive and negative shifts in holding current, respectively. LY341495 and (2S,2′R,3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine (DCG-IV, a group II agonist) elicited negative and positive shifts in holding current, respectively. The AIDA and LY341495 elicited currents persisted in TTX. Finally, in current clamp, LY341495 depolarized cells by ∼2 mV and increased the number of action potentials to a given depolarizing current pulse. Thus ambient levels of glutamate tonically activate mGluRs and regulate cortical excitability.

Nicotinic activity depresses synaptic potentiation in layer V pyramidal neurons of mouse insular cortex

Neuroscience ◽  
2017 ◽  
Vol 358 ◽  
pp. 13-27 ◽  
Author(s):  
Hajime Sato ◽  
Tsutomu Kawano ◽  
Dong Xu Yin ◽  
Takafumi Kato ◽  
Hiroki Toyoda
Keyword(s):  
Pyramidal Neurons ◽  
Insular Cortex ◽  
Synaptic Potentiation ◽  
Layer V

Dendritic changes of the pyramidal neurons in layer V of sensory-motor cortex of the rat brain during the postresuscitation period

Resuscitation ◽  
1997 ◽  
Vol 35 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Victor A Akulinin ◽  
Sergey S Stepanov ◽  
Valeriy V Semchenko ◽  
Pavel V Belichenko
Keyword(s):  
Motor Cortex ◽  
Rat Brain ◽  
Pyramidal Neurons ◽  
Postresuscitation Period ◽  
Sensory Motor ◽  
Layer V

scholarly journals Sex-dependent role for EPHB2 in brain development and autism-associated behavior

2021 ◽  
Author(s):  
Ahlem Assali ◽  
Jennifer Y. Cho ◽  
Evgeny Tsvetkov ◽  
Abha R. Gupta ◽  
Christopher W. Cowan
Keyword(s):  
Pyramidal Neurons ◽  
De Novo ◽  
Repetitive Behavior ◽  
Autism Spectrum ◽  
Repetitive Behaviors ◽  
Male Mice ◽  
Sensory Sensitivity ◽  
Hyperactivity Disorder ◽  
Specific Effects ◽  
Layer V

AbstractAutism spectrum disorder (ASD) is characterized by impairments in social communication and interaction and restricted, repetitive behaviors. It is frequently associated with comorbidities, such as attention-deficit hyperactivity disorder, altered sensory sensitivity, and intellectual disability. A de novo nonsense mutation in EPHB2 (Q857X) was discovered in a female patient with ASD [13], revealing EPHB2 as a candidate ASD risk gene. EPHB2 is a receptor tyrosine kinase implicated in axon guidance, synaptogenesis, and synaptic plasticity, positioning it as a plausible contributor to the pathophysiology of ASD and related disorders. In this study, we show that the Q857X mutation produced a truncated protein lacking forward signaling and that global disruption of one EphB2 allele (EphB2+/−) in mice produced several behavioral phenotypes reminiscent of ASD and common associated symptoms. EphB2+/− female, but not male, mice displayed increased repetitive behavior, motor hyperactivity, and learning and memory deficits, revealing sex-specific effects of EPHB2 hypofunction. Moreover, we observed a significant increase in the intrinsic excitability, but not excitatory/inhibitory ratio, of motor cortex layer V pyramidal neurons in EphB2+/− female, but not male, mice, suggesting a possible mechanism by which EPHB2 hypofunction may contribute to sex-specific motor-related phenotypes. Together, our findings suggest that EPHB2 hypofunction, particularly in females, is sufficient to produce ASD-associated behaviors and altered cortical functions in mice.

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