scholarly journals When the air hits your brain: decreased arterial pulsatility after craniectomy leading to impaired glymphatic flow

2020 ◽  
Vol 133 (1) ◽  
pp. 210-223 ◽  
Author(s):  
Benjamin A. Plog ◽  
Nanhong Lou ◽  
Clifford A. Pierre ◽  
Alex Cove ◽  
H. Mark Kenney ◽  
...  
Keyword(s):  
Cognitive Deficits ◽  
Brain Function ◽  
Microglial Activation ◽  
Ex Vivo ◽  
Brain Parenchyma ◽  
Neurological Function ◽  
Neurosurgical Procedures ◽  
Two Photon ◽  
Syndrome Of The Trephined

OBJECTIVECranial neurosurgical procedures can cause changes in brain function. There are many potential explanations, but the effect of simply opening the skull has not been addressed, except for research into syndrome of the trephined. The glymphatic circulation, by which CSF and interstitial fluid circulate through periarterial spaces, brain parenchyma, and perivenous spaces, depends on arterial pulsations to provide the driving force for bulk flow; opening the cranial cavity could dampen this force. The authors hypothesized that a craniectomy, without any other pathological insult, is sufficient to alter brain function due to reduced arterial pulsatility and decreased glymphatic flow. Furthermore, they postulated that glymphatic impairment would produce activation of astrocytes and microglia; with the reestablishment of a closed cranial compartment, the glymphatic impairment, astrocytic/microglial activation, and neurobehavioral decline caused by opening the cranial compartment might be reversed.METHODSUsing two-photon in vivo microscopy, the pulsatility index of cortical vessels was quantified through a thinned murine skull and then again after craniectomy. Glymphatic influx was determined with ex vivo fluorescence microscopy of mice 0, 14, 28, and 56 days following craniectomy or cranioplasty; brain sections were immunohistochemically labeled for GFAP and CD68. Motor and cognitive performance was quantified with rotarod and novel object recognition tests at baseline and 14, 21, and 28 days following craniectomy or cranioplasty.RESULTSPenetrating arterial pulsatility decreased significantly and bilaterally following unilateral craniectomy, producing immediate and chronic impairment of glymphatic CSF influx in the ipsilateral and contralateral brain parenchyma. Craniectomy-related glymphatic dysfunction was associated with an astrocytic and microglial inflammatory response, as well as with the development of motor and cognitive deficits. Recovery of glymphatic flow preceded reduced gliosis and return of normal neurological function, and cranioplasty accelerated this recovery.CONCLUSIONSCraniectomy causes glymphatic dysfunction, gliosis, and changes in neurological function in this murine model of syndrome of the trephined.

Endothelial glycocalyx thickness and platelet-vessel wall interactions during atherogenesis

2011 ◽  
Vol 106 (11) ◽  
pp. 939-946 ◽  
Author(s):  
Mirjam oude Egbrink ◽  
Viviane Heijnen ◽  
Remco Megens ◽  
Wim Engels ◽  
Hans Vink ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Laser Scanning ◽  
Ex Vivo ◽  
Laser Scanning Microscopy ◽  
Endothelial Glycocalyx ◽  
Knock Out ◽  
Two Photon ◽  
Common Carotid Arteries ◽  
Wall Interactions

SummaryThe endothelial glycocalyx (EG), the luminal cover of endothelial cells, is considered to be atheroprotective. During atherogenesis, platelets adhere to the vessel wall, possibly triggered by simultaneous EG modulation. It was the objective of this study to investigate both EG thickness and platelet-vessel wall interactions during atherogenesis in the same experimental model. Intravital fluorescence microscopy was used to study platelet-vessel wall interactions in vivo in common carotid arteries and bifurcations of C57bl6/J (B6) and apolipoprotein E knock-out (ApoE-/-) mice (age 7 – 31 weeks). At the same locations, EG thickness was determined ex vivo using two-photon laser scanning microscopy. In ApoE-/- bifurcations the overall median level of adhesion was 48 platelets/mm2 (interquartile range: 16 – 80), which was significantly higher than in B6 bifurcations (0 (0 – 16), p = 0.001). This difference appeared to result from a significant age-dependent increase in ApoE-/- mice, while no such change was observed in B6 mice. At the same time, the EG in ApoE-/- bifurcations was significantly thinner than in B6 bifurcations (2.2 vs. 2.5 μm, respectively; p < 0.05). This resulted from the fact that in B6 bifurcations EG thickness increased with age (from 2.4 μm in young mice to 3.0 μm in aged ones), while in bifurcations of ApoE-/- mice this growth appeared to be absent (2.2 μm at all ages). During atherogenesis, platelet adhesion to the wall of the carotid artery bifurcation increases significantly. At the same location, EG growth with age is hampered. Therefore, glycocalyx-reinforcing strategies could possibly ameliorate atherosclerosis.

scholarly journals Microglia motility depends on neuronal activity and promotes structural plasticity in the hippocampus

2019 ◽  
Author(s):  
Felix C. Nebeling ◽  
Stefanie Poll ◽  
Lena C. Schmid ◽  
Manuel Mittag ◽  
Julia Steffen ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Dendritic Spines ◽  
Synapse Formation ◽  
Brain Parenchyma ◽  
Two Photon ◽  
Contact Rates ◽  
Health And Disease ◽  
The Impact ◽  
The Brain

AbstractMicroglia, the resident immune cells of the brain, play a complex role in health and disease. They actively survey the brain parenchyma by physically interacting with other cells and structurally shaping the brain. Yet, the mechanisms underlying microglia motility and their significance for synapse stability, especially during adulthood, remain widely unresolved. Here we investigated the impact of neuronal activity on microglia motility and its implication for synapse formation and survival. We used repetitive two-photon in vivo imaging in the hippocampus of awake mice to simultaneously study microglia motility and their interaction with synapses. We found that microglia process motility depended on neuronal activity. Simultaneously, more dendritic spines emerged in awake compared to anesthetized mice. Interestingly, microglia contact rates with individual dendritic spines were associated with their stability. These results suggest that microglia are not only sensing neuronal activity, but participate in synaptic rewiring of the hippocampus during adulthood, which has profound relevance for learning and memory processes.

Antibodies to β-Amyloid Decrease the Blood-to-Brain Transfer of β-Amyloid Peptide1

2002 ◽  
Vol 227 (8) ◽  
pp. 609-615 ◽  
Author(s):  
Weihong Pan ◽  
Beka Solomon ◽  
Lawrence M. Maness ◽  
Abba J. Kastin
Keyword(s):  
Ex Vivo ◽  
Amyloid Β ◽  
Brain Perfusion ◽  
Brain Parenchyma ◽  
Amyloid Angiopathy ◽  
Β Amyloid ◽  
Blocking Antibodies ◽  
The Brain

Amyloid-β peptides (Aβ) play an important role in the pathophysiology of dementia of the Alzheimer's type and in amyloid angiopathy. Aβ outside the CNS could contribute to plaque formation in the brain where its entry would involve interactions with the blood-brain barrier (BBB). Effective antibodies to Aβ have been developed in an effort to vaccinate against Alzheimer's disease. These antibodies could interact with Aβ in the peripheral blood, block the passage of Aβ across the BBB, or prevent Aβ deposition within the CNS. To determine whether the blocking antibodies act at the BBB level, we examined the influx of radiolabeled Aβ (125I-Aβ1-40) into the brain after ex-vivo incubation with the antibodies. Antibody mAb3D6 (élan Company) reduced the blood-to-brain influx of Aβ after iv bolus injection. It also significantly decreased the accumulation of Aβ in brain parenchyma. To confirm the in-vivo study and examine the specificity of mAb3D6, in-situ brain perfusion in serum-free buffer was performed after incubation of 125I-Aβ1-40 with another antibody mAbmc1 (DAKO Company). The presence of mAbmc1 also caused significant reduction of the influx of Aβ into the brain after perfusion. Therefore, effective antibodies to Aβ can reduce the influx of Aβ1-40 into the brain.

scholarly journals Ultrasound-assisted gatifloxacin delivery in mouse cornea, in vivo

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Uk Jegal ◽  
Jun Ho Lee ◽  
Jungbin Lee ◽  
Hyerin Jeong ◽  
Myoung Joon Kim ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Ophthalmic Solution ◽  
Ultrasound Treatment ◽  
Ocular Infection ◽  
Therapeutic Effects ◽  
Corneal Surface ◽  
Ultrasound Waves ◽  
Two Photon Microscopy ◽  
Two Photon

Abstract Gatifloxacin is a 4th generation fluoroquinolone antibiotic used in the clinic to treat ocular infection. One limitation of gatifloxacin is its relatively poor corneal penetration, and the increase of its trans-corneal delivery would be beneficial to reduce the amount or frequency of daily dose. In this study, ultrasound treatment was applied to enhance the trans-corneal delivery of gatifloxacin without damage. Experiments were conducted on mouse eyes in ex vivo and in vivo conditions. Ultrasound waves with 1 MHz in frequency, 1.3 W/cm2 in intensity were applied onto the mouse cornea for 5 minutes, and then gatifloxacin ophthalmic solution was instilled and left there for 10 minutes. 3D gatifloxacin distribution in the cornea was measured by two-photon microscopy (TPM) imaging based on its intrinsic fluorescence. Longitudinal TPM imaging of ultrasound treated mouse corneas showed the increase of initial gatifloxacin intensities on the corneal surface compared to untreated mouse corneas by 67%, and then the increased gatifloxacin delivery into the cornea from the surface at later time. The delivered gatifloxacin in the corneal epithelium stayed longer in the ultrasound treated corneas than in the untreated corneas. The enhanced trans-corneal delivery and extended stay of gatifloxacin in the mouse cornea by ultrasound treatment could be beneficial for therapeutic effects. This study demonstrated the detail process of enhanced trans-corneal gatifloxacin delivery by ultrasound treatment.

scholarly journals Two-Photon Microscopy Allows Imaging and Characterization of Cochlear Microvasculature In Vivo

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Friedrich Ihler ◽  
Mattis Bertlich ◽  
Bernhard Weiss ◽  
Steffen Dietzel ◽  
Martin Canis
Keyword(s):  
Fluorescence Microscopy ◽  
Inner Ear ◽  
Ex Vivo ◽  
Small Scale ◽  
Published Data ◽  
Cochlear Blood Flow ◽  
Two Photon ◽  
Two Photon Fluorescence ◽  
Photon Fluorescence

Impairment of cochlear blood flow has been discussed as factor in the pathophysiology of various inner ear disorders. However, the microscopic study of cochlear microcirculation is limited due to small scale and anatomical constraints. Here, two-photon fluorescence microscopy is applied to visualize cochlear microvessels. Guinea pigs were injected with Fluorescein isothiocyanate- or Texas red-dextrane as plasma marker. Intravital microscopy was performed in four animals and explanted cochleae from four animals were studied. The vascular architecture of the cochlea was visualized up to a depth of90.0±22.7 μm. Imaging yielded a mean contrast-to-noise ratio (CNR) of3.3±1.7. Mean diameter in vivo was16.5±6.0 μm for arterioles and8.0±2.4 μm for capillaries. In explanted cochleae, the diameter of radiating arterioles and capillaries was measured with12.2±1.6 μm and6.6±1.0 μm, respectively. The difference between capillaries and arterioles was statistically significant in both experimental setups (P<0.001andP=0.022, two-way ANOVA). Measured vessel diameters in vivo and ex vivo were in agreement with published data. We conclude that two-photon fluorescence microscopy allows the investigation of cochlear microvessels and is potentially a valuable tool for inner ear research.

scholarly journals Exercise training improves motor skill learning via selective activation of mTOR

2019 ◽  
Vol 5 (7) ◽  
pp. eaaw1888 ◽  
Author(s):  
Kai Chen ◽  
Yuhan Zheng ◽  
Ji-an Wei ◽  
Huan Ouyang ◽  
Xiaodan Huang ◽  
...  
Keyword(s):  
Exercise Training ◽  
Motor Learning ◽  
Cognitive Deficits ◽  
Molecular Mechanisms ◽  
Pyramidal Neurons ◽  
Ex Vivo ◽  
Mtor Pathway ◽  
Skill Learning ◽  
Mechanistic Target Of Rapamycin

Physical exercise improves learning and memory, but little in vivo evidence has been provided to illustrate the molecular mechanisms. Here, we show that chronic treadmill exercise activates the mechanistic target of rapamycin (mTOR) pathway in mouse motor cortex. Both ex vivo and in vivo recordings suggest that mTOR activation leads to potentiated postsynaptic excitation and enhanced neuronal activity of layer 5 pyramidal neurons after exercise, in association with increased oligodendrogenesis and axonal myelination. Exercise training also increases dendritic spine formation and motor learning. Together, exercise activates mTOR pathway, which is necessary for spinogenesis, neuronal activation, and axonal myelination leading to improved motor learning. This model provides new insights for neural network adaptations through exercises and supports the intervention of cognitive deficits using exercise training.

Two-Photon Imaging of Cellular Activities in Oxygen Sensing Tissues

2008 ◽  
Vol 14 (6) ◽  
pp. 519-525 ◽  
Author(s):  
Christoph Wotzlaw ◽  
Utta Berchner-Pfannschmidt ◽  
Joachim Fandrey ◽  
Helmut Acker
Keyword(s):  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Oxygen Sensing ◽  
Rat Kidney ◽  
Hypoxia Inducible Factor ◽  
The Body ◽  
Cellular Functions ◽  
Protein Protein Interaction ◽  
Two Photon

AbstractThe cellular oxygen sensing system of the body ensures appropriate adaptation of cellular functions toward hypoxia by regulating gene expression and ion channel activity. Two-photon laser microscopy is an ideal tool to study and prove the relevance of the molecular mechanisms within oxygen sensing pathways on the cellular and complex tissue or organ level. Images of hypoxia inducible factor 1 (HIF-1) subunit nuclear mobility and protein-protein interaction in living cells, of hypoxia-induced changes in membrane potential and intracellular calcium of live ex vivo carotid bodies as well as of rat kidney proximal tubulus function in vivo, will be shown.

scholarly journals Loss of clusterin shifts amyloid deposition to the cerebrovasculature via disruption of perivascular drainage pathways

2017 ◽  
Vol 114 (33) ◽  
pp. E6962-E6971 ◽  
Author(s):  
Aleksandra M. Wojtas ◽  
Silvia S. Kang ◽  
Benjamin M. Olley ◽  
Maureen Gatherer ◽  
Mitsuru Shinohara ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Amyloid Β ◽  
Fold Increase ◽  
Brain Parenchyma ◽  
Amyloid Angiopathy ◽  
Clinical Complications ◽  
Perivascular Drainage

Alzheimer’s disease (AD) is characterized by amyloid-β (Aβ) peptide deposition in brain parenchyma as plaques and in cerebral blood vessels as cerebral amyloid angiopathy (CAA). CAA deposition leads to several clinical complications, including intracerebral hemorrhage. The underlying molecular mechanisms that regulate plaque and CAA deposition in the vast majority of sporadic AD patients remain unclear. The clusterin (CLU) gene is genetically associated with AD and CLU has been shown to alter aggregation, toxicity, and blood–brain barrier transport of Aβ, suggesting it might play a key role in regulating the balance between Aβ deposition and clearance in both brain and blood vessels. Here, we investigated the effect of CLU on Aβ pathology using the amyloid precursor protein/presenilin 1 (APP/PS1) mouse model of AD amyloidosis on a Clu+/+ or Clu−/− background. We found a marked decrease in plaque deposition in the brain parenchyma but an equally striking increase in CAA within the cerebrovasculature of APP/PS1;Clu−/− mice. Surprisingly, despite the several-fold increase in CAA levels, APP/PS1;Clu−/− mice had significantly less hemorrhage and inflammation. Mice lacking CLU had impaired clearance of Aβ in vivo and exogenously added CLU significantly prevented Aβ binding to isolated vessels ex vivo. These findings suggest that in the absence of CLU, Aβ clearance shifts to perivascular drainage pathways, resulting in fewer parenchymal plaques but more CAA because of loss of CLU chaperone activity, complicating the potential therapeutic targeting of CLU for AD.

scholarly journals Emergent cortical circuit dynamics contain dense, interwoven ensembles of spike sequences

2017 ◽  
Vol 118 (3) ◽  
pp. 1914-1925 ◽  
Author(s):  
Joseph B. Dechery ◽  
Jason N. MacLean
Keyword(s):  
Ex Vivo ◽  
Temporal Coding ◽  
Population Activity ◽  
Flexible Assembly ◽  
Two Photon ◽  
Phase Sequence ◽  
Spike Sequences ◽  
Neuronal Assembly ◽  
Large Repertoire

Temporal codes are theoretically powerful encoding schemes, but their precise form in the neocortex remains unknown in part because of the large number of possible codes and the difficulty in disambiguating informative spikes from statistical noise. A biologically plausible and computationally powerful temporal coding scheme is the Hebbian assembly phase sequence (APS), which predicts reliable propagation of spikes between functionally related assemblies of neurons. Here, we sought to measure the inherent capacity of neocortical networks to produce reliable sequences of spikes, as would be predicted by an APS code. To record microcircuit activity, the scale at which computation is implemented, we used two-photon calcium imaging to densely sample spontaneous activity in murine neocortical networks ex vivo. We show that the population spike histogram is sufficient to produce a spatiotemporal progression of activity across the population. To more comprehensively evaluate the capacity for sequential spiking that cannot be explained by the overall population spiking, we identify statistically significant spike sequences. We found a large repertoire of sequence spikes that collectively comprise the majority of spiking in the circuit. Sequences manifest probabilistically and share neuron membership, resulting in unique ensembles of interwoven sequences characterizing individual spatiotemporal progressions of activity. Distillation of population dynamics into its constituent sequences provides a way to capture trial-to-trial variability and may prove to be a powerful decoding substrate in vivo. Informed by these data, we suggest that the Hebbian APS be reformulated as interwoven sequences with flexible assembly membership due to shared overlapping neurons. NEW & NOTEWORTHY Neocortical computation occurs largely within microcircuits comprised of individual neurons and their connections within small volumes (<500 μm3). We found evidence for a long-postulated temporal code, the Hebbian assembly phase sequence, by identifying repeated and co-occurring sequences of spikes. Variance in population activity across trials was explained in part by the ensemble of active sequences. The presence of interwoven sequences suggests that neuronal assembly structure can be variable and is determined by previous activity.

scholarly journals Calcium Imaging of Living Astrocytes in the Mouse Spinal Cord following Sensory Stimulation

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Giovanni Cirillo ◽  
Daniele De Luca ◽  
Michele Papa
Keyword(s):  
Spinal Cord ◽  
Cultured Cells ◽  
Ex Vivo ◽  
Sensory Stimulation ◽  
Widespread Application ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Heart Beating ◽  
Sensory Activity

Astrocytic Ca2+dynamics have been extensively studied inex vivomodels; however, the recent development of two-photon microscopy and astrocyte-specific labeling has allowed the study of Ca2+signaling in living central nervous system. Ca2+waves in astrocytes have been described in cultured cells and slice preparations, but evidence for astrocytic activation during sensory activity is lacking. There are currently few methods to image living spinal cord: breathing and heart-beating artifacts have impeded the widespread application of this technique. We here imaged the living spinal cord by two-photon microscopy in C57BL6/J mice. Through pressurized injection, we specifically loaded spinal astrocytes using the red fluorescent dye sulforhodamine 101 (SR101) and imaged astrocytic Ca2+levels with Oregon-Green BAPTA-1 (OGB). Then, we studied astrocytic Ca2+levels at rest and after right electrical hind paw stimulation. Sensory stimulation significantly increased astrocytic Ca2+levels within the superficial dorsal horn of the spinal cord compared to rest. In conclusion,in vivomorphofunctional imaging of living astrocytes in spinal cord revealed that astrocytes actively participate to sensory stimulation.

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