Search

In this article, move contrast X-ray imaging (MCXI) based on high-brightness synchrotron radiation is developed. Experiments with live rodents demonstrate the practicability of the MCXI method for sensitive and intact imaging of microvessels in vivo., Early stages of diseases, including stroke, hypertension, angiogenesis of tumours, spinal cord injuries, etc., are closely associated with the lesions of microvasculature. Rodent models of human vascular diseases are extensively used for the preclinical investigation of the disease evolution and therapy with synchrotron radiation. Therefore, non-invasive and in vivo X-ray imaging with high sensitivity and clarity is desperately needed to visualize the microvessels in live-animal models. Contrast agent is essential for the in vivo X-ray imaging of vessels and angiomatous tissue. Because of the non-rigid motion of adjacent tissues, the short circulation time and the intermittent flow of contrast agents in vessels, it is a great challenge for the traditional X-ray imaging methods to achieve well defined images of microvessels in vivo. In this article, move contrast X-ray imaging (MCXI) based on high-brightness synchrotron radiation is developed to overcome the intrinsic defects in conventional methods. Experiments with live rodents demonstrate the practicability of the MCXI method for sensitive and intact imaging of microvessels in vivo.

Blood-brain barrier (BBB) disruption underlies the vasogenic edema and neuronal cell death induced by acute ischemic stroke. Reducing this disruption has therapeutic potential. Transcranial focused ultrasound stimulation has shown neuromodulatory and neuroprotective effects in various brain diseases including ischemic stroke. Ultrasound stimulation can reduce inflammation and promote angiogenesis and neural circuit remodeling. However, its effect on the BBB in the acute phase of ischemic stroke is unknown. In this study of mice subjected to middle cerebral artery occlusion for 90 minutes, low-intensity low-frequency (0.5 MHz) transcranial focused ultrasound stimulation was applied 2, 4, and 8 hours after occlusion. Ultrasound stimulation reduced edema volume, improved neurobehavioral outcomes, improved BBB integrity (enhanced tight junction protein ZO-1 expression and reduced IgG leakage), and reduced secretion of the inflammatory factors tumor necrosis factor-α and activation of matrix metalloproteinase-9 in the ischemic brain. Our results show that low-intensity ultrasound stimulation attenuated BBB disruption and edema formation, which suggests it may have therapeutic use in ischemic brain disease as a protector of BBB integrity.

Microglial activation participates in white matter injury after cerebral hypoperfusion. However, the underlying mechanism is unclear. Here, we explore whether activated microglia aggravate white matter injury via complement C3-C3aR pathway after chronic cerebral hypoperfusion. Methods: Adult male Sprague-Dawley rats (n = 80) underwent bilateral common carotid artery occlusion for 7, 14, and 28 days. Cerebral vessel density and blood flow were examined by synchrotron radiation angiography and three-dimensional arterial spin labeling. Neurobehavioral assessments, CLARITY imaging, and immunohistochemistry were performed to evaluate activation of microglia and C3-C3aR pathway. Furthermore, C3aR knockout mice were used to establish the causal relationship of C3-C3aR signaling on microglia activation and white matter injury after hypoperfusion. Results: Cerebral vessel density and blood flow were reduced after hypoperfusion (p

Background Farnesoid X receptor (FXR) is a nuclear receptor that plays a critical role in controlling cell apoptosis in diverse diseases. Previous studies have shown that knocking out FXR improved cardiac function by reducing cardiomyocyte apoptosis in myocardial ischemic mice. However, the role of FXR after cerebral ischemia remains unknown. In this study, we explored the effects and mechanisms of FXR knockout (KO) on the functional recovery of mice post cerebral ischemia-reperfusion. Methods Adult male C57BL/6 wild type and FXR KO mice were subjected to 90-min transient middle cerebral artery occlusion (tMCAO). The mice were divided into five groups: sham, wild-type tMCAO, FXR KO tMCAO, wild-type tMCAO treated with calcium agonist Bayk8644, and FXR KO tMCAO treated with Bayk8644. FXR expression was examined using immunohistochemistry and Western blot. Brain infarct and brain atrophy volume were examined at 3 and 14 days after stroke respectively. Neurobehavioral tests were conducted up to 14 days after stroke. The protein levels of apoptotic factors (Bcl-2, Bax, and Cleaved caspase-3) and mRNA levels of pro-inflammatory factors (TNF-α, IL-6, IL-1β, IL-17, and IL-18) were examined using Western blot and RT-PCR. TUNEL staining and calcium imaging were obtained using confocal and two-photon microscopy. Results The expression of FXR was upregulated after ischemic stroke, which is located in the nucleus of the neurons. FXR KO was found to reduce infarct volume and promote neurobehavioral recovery following tMCAO compared to the vehicle. The expression of apoptotic and pro-inflammatory factors decreased in FXR KO mice compared to the control. The number of NeuN+/TUNEL+ cells declined in the peri-infarct area of FXR KO mice compared to the vehicle. We further demonstrated that inhibition of FXR reduced calcium overload and addition of ionomycin could reverse this neuroprotective effect in vitro. What is more, in vivo results showed that enhancement of intracellular calcium concentrations could aggravate ischemic injury and reverse the neuroprotective effect of FXR KO in mice. Conclusions FXR KO can promote neurobehavioral recovery and attenuate ischemic brain injury, inflammatory release, and neuronal apoptosis via reducing calcium influx, suggesting its role as a therapeutic target for stroke treatments.

Transcranial focused ultrasound stimulation (tFUS) regulates neural activity in different brain regions in humans and animals. However, the role of ultrasound stimulation in modulating neural activity and promoting neurorehabilitation in the ischemic brain is largely unknown. In the present study, we explored the effect of tFUS on neurological rehabilitation and the underlying mechanism. Adult male ICR mice (n=42) underwent transient middle cerebral artery occlusion. One week after brain ischemia, low frequency (0.5 MHz) tFUS was applied to stimulate the ischemic hemisphere of mice for 7 consecutive days (10 minutes daily). Brain infarct volume, neurobehavioral tests, microglia activation, IL-10 and IL-10R levels were further assessed for up to 14 days. We found that the brain infarct volume was significantly reduced in the tFUS treated mice compared to that in the non-treated mice (p

Background Clearance of damaged cells is beneficial for the functional recovery after brain injury. Phagocytosis of tissue and cell debris is an important function of microglia during the development and pathological diseases. However, which specific phagocytic receptor mediates microglial phagocytosis after ischemic stroke is obscure. Methods ICR mice (n=59) underwent 90 minutes transient middle cerebral artery occlusion. P2Y6R, Iba1, GFAP and Tuj-1 double immunostainings were performed to determine P2Y6 receptor location. MRS2578 was injected into mice to inhibit P2Y6 receptor activity. Iba1 and TUNEL staining were performed to examine microglia phagocytosis. Modified neurological severity scores and Grid walking test were used to evaluate the neurological function after ischemic stoke. The expression of IL-1 α, IL-1 β, IL-6, IL-10, TNF-α, TGF-β and MPO was used to examine the inflammation response in the brain. Results The expression of P2Y6 receptor in microglia increased within three days after transient middle cerebral artery occlusion. Inhibition of microglial phagocytosis by the selective inhibitor MRS2578 enlarged the brain atrophy and edema volume after ischemic stroke, subsequently aggravated neurological function using modified neurological severity scores and Grid walking test. MRS2578 treatment had no effect on the expression of IL-1α, IL-1β, IL-6, IL-10, TNF-α, TGF-β and MPO after ischemic stroke, which suggested that it had no effect on the inflammation in the brain. Finally, we found that the expression of myosin light chain kinase decreased after microglial phagocytosis inhibition in ischemic mice, which suggested that myosin light chain kinase was involved in P2Y6 receptor mediated phagocytosis. Conclusion Our results indicated that the P2Y6 receptor mediated microglial phagocytosis played an important role during the acute stage of ischemic stroke, which was a potential target for ischemic stroke treatment.

Brain edema primarily occurs as a consequence of various cerebral injuries including ischemic stroke. Excessive accumulation of brain water content causes a gradual expansion of brain parenchyma, decreased blood flow and increased intracranial pressure and, ultimately, cerebral herniation and death. Current clinical treatment for ischemic edema is very limited, therefore, it is urgent to develop novel treatment strategies. Mounting evidence has demonstrated that AQP4, a water channel protein, is closely correlated with brain edema and could be an optimal therapeutic target for the reduction of ischemic brain edema. AQP4 is prevalently distributed in the central nervous system, and mainly regulates water flux in brain cells under normal and pathological conditions. This review focuses on the underlying mechanisms of AQP4 related to its dual role in edema formation and elimination.

Dl-3-N-butylphthalide (NBP) is approved in China for the treatment of ischemic stroke. Previous studies have shown that NBP promotes recovery after stroke via multiple mechanisms. However, the effect of NBP on vascular function and thrombosis remains unclear. Here, we aim to study the effect of NBP on vascular function using a rat model of transient middle cerebral artery occlusion (MCAO) and a state-of-the-art high-resolution synchrotron radiation angiography. Eighty SD rats underwent MCAO surgery. NBP (90 mg/kg) was administrated daily by gavage. Synchrotron radiation angiography was used to evaluate the cerebral vascular perfusion, vasoconstriction, and vasodilation in real-time. Neurological scores, brain infarction and atrophy were evaluated. Real-time PCR was used to assess the expression levels of thrombosis and vasoconstriction-related genes. Results revealed that NBP attenuated thrombosis after MCAO and reduced brain infarct and atrophy volume. NBP administrated at 1 and 4 h after MCAO prevented the vasoconstriction of the artery and maintained its diameter at normal level. Administrated at one week after surgery, NBP functioned as a vasodilator in rats after MCAO while displayed no vasodilating effect in sham group. Our results suggested that NBP attenuates brain injury via increasing the regional blood flow by reducing thrombosis and vasoconstriction.

Introduction: Ultrasonic brain stimulation regulates neural activity in different brain regions in normal humans and animals, and promotes neurogenesis in normal mouse brain. However, the role of ultrasonic stimulation in modulating neural plasticity in the ischemic brain is largely unknown. Hypothesis: To explore the effect of ultrasonic brain stimulation on neurological rehabilitation and the possible underlying mechanism. Methods: Adult CD-1 mice (n=18) underwent transient middle cerebral artery occlusion (60 min). One week after brain ischemia, 0.5M HZ frequency brain stimulation was applied transcranially to the ischemic hemisphere of mice for 7 consecutive days. Brain infarct volume and neurological behavioral tests were assessed at 1, 7 and 14 days after brain ischemia. The expression of proteins critical to neuronal development, in particular BrdU and DCX, and IL-10R were examined to explore the underlying mechanism. Results: We found that the brain infarct volume was significantly attenuated in the ultrasonic stimulated mice compared to the non-stimulated mice ( p p + /DCX + cells in the subventricular zone of ischemic mice, suggesting this stimulation promoted neurogenesis in mice after cerebral ischemia. Furthermore, IL-10R expression was substantially up-regulated in the perifocal region and subventricular zone of ischemic mice after ultrasonic stimulation ( p Conclusions: We concluded that ultrasonic stimulation provided a unique technique to promote neurorehabilitation. Ultrasonic stimulation enhanced neural rehabilitation through promoting neural precursor cell proliferation, which may be modulated by IL-10/IL-10R mediated immune-regulation. (Funded by SJTU YG2016MS62)

Background and Purpose— Striatal GABAergic neuron is known as a key regulator in adult neurogenesis. However, the specific role of striatal GABAergic neuronal activity in the promotion of neurological recovery after ischemic stroke remains unknown. Here, we used optogenetic approach to investigate these effects and mechanism. Methods— Laser stimulation was delivered via an implanted optical fiber to inhibit or activate the striatal GABAergic neurons in Gad2-Arch-GFP or Gad2-ChR2-tdTomato mice (n=80) 1 week after 60-minute transient middle cerebral artery occlusion. Neurological severity score, brain atrophy volume, microvessel density, and cell morphological changes were examined using immunohistochemistry. Gene expression and protein levels of related growth factors were further examined using real-time polymerase chain reaction and Western blotting. Results— Inhibiting striatal GABAergic neuronal activity improved functional recovery, reduced brain atrophy volume, and prohibited cell death compared with the control ( P P P Conclusions— After ischemic stroke, optogenetic inhibition of GABAergic neurons upregulated bFGF expression by endothelial cells and promoted neurobehavioral recovery, possibly orchestrated by astrocytes. Optogenetically inhibiting neuronal activity provides a novel approach to promote neurological recovery.

BackgroundHealthy plasma therapy reverses cognitive deficits and promotes neuroplasticity in ageing brain disease. However, whether healthy plasma therapy improve blood–brain barrier integrity after stroke remains unknown.MethodsHere, we intravenously injected healthy female mouse plasma into adult female ischaemic stroke C57BL/6 mouse induced by 90 min transient middle cerebral artery occlusion for eight consecutive days. Infarct volume, brain atrophy and neurobehavioural tests were examined to assess the outcomes of plasma treatment. Cell apoptosis, blood–brain barrier integrity and fibroblast growth factor 21 knockout mice were used to explore the underlying mechanism.ResultsPlasma injection improved neurobehavioural recovery and decreased infarct volume, brain oedema and atrophy after stroke. Immunostaining showed that the number of transferase dUTP nick end labelling+/NeuN+ cells decreased in the plasma-injected group. Meanwhile, plasma injection reduced ZO-1, occluding and claudin-5 tight junction gap formation and IgG extravasation at 3 days after ischaemic stroke. Western blot results showed that the FGF21 expression increased in the plasma-injected mice. However, using FGF21 knockout mouse plasma injecting to the ischaemic wild-type mice diminished the neuroprotective effects.ConclusionsOur study demonstrated that healthy adult plasma treatment protected the structural and functional integrity of blood–brain barrier, reduced neuronal apoptosis and improved functional recovery via FGF21, opening a new avenue for ischaemic stroke therapy.