Stratification substantially reduces behavioral variability in the hypoxic-ischemic stroke model

PyMouseTracks: Flexible Computer Vision and RFID-Based System for Multiple Mouse Tracking and Behavioral Assessment

PyMouseTracks (PMT) is a scalable and customizable computer vision and radio frequency identification (RFID)-based system for multiple rodent tracking and behavior assessment that can be set up within minutes in any user-defined arena at minimal cost. PMT is composed of the online Raspberry Pi (RPi)-based video and RFID acquisition with subsequent offline analysis tools. The system is capable of tracking up to six mice in experiments ranging from minutes to days. PMT maintained a minimum of 88% detections tracked with an overall accuracy >85% when compared with manual validation of videos containing one to four mice in a modified home-cage. As expected, chronic recording in home-cage revealed diurnal activity patterns. In open-field, it was observed that novel noncagemate mouse pairs exhibit more similarity in travel trajectory patterns than cagemate pairs over a 10-min period. Therefore, shared features within travel trajectories between animals may be a measure of sociability that has not been previously reported. Moreover, PMT can interface with open-source packages such as DeepLabCut and Traja for pose estimation and travel trajectory analysis, respectively. In combination with Traja, PMT resolved motor deficits exhibited in stroke animals. Overall, we present an affordable, open-sourced, and customizable/scalable mouse behavior recording and analysis system.

Habilitation Improves Mouse Gait Development Following Neonatal Brain Injury

OBJECTIVES

Neonatal brain injury during gait development disrupts neural circuits and causes permanent gait dysfunction. Rehabilitation as an intervention to improve impaired gait function has been used in adults as a treatment for stroke and spinal cord injury. However, although neonates have greater neuroplasticity and regenerative capacity than adults, normal gait development and the effects of habilitation on gait function following neonatal brain injury are largely unknown.

METHODS

In this study, we generated cryogenic injury in mice at postnatal day 2 and subsequently performed habilitative training to promote autonomous limb movement for 4 weeks. We also quantitatively analyzed the gait acquisition process in developing mice using the Catwalk XT system.

RESULTS

Using quantitative gait analyses, we showed that during normal gait development in mice, stance phase function matures later than swing phase function. We also demonstrated that habilitation in which active limb movements were enhanced by suspending mice with a rubber band with no floor grounding promotes motor learning, including gait function, in mice with impaired acquisition of gait function resulting from neonatal brain injury.

CONCLUSIONS

Our findings provide a basis for research on gait development in mice and suggest new habilitation strategies for patients with impaired gait development caused by perinatal brain diseases such as hypoxic-ischemic encephalopathy and periventricular leukomalacia.

Behavioural phenotypes in the cuprizone model of central nervous system demyelination

The feeding of cuprizone (CPZ) to animals has been extensively used to model the processes of demyelination and remyelination, with many papers adopting a narrative linked to demyelinating conditions like multiple sclerosis (MS), the aetiology of which is unknown. However, no current animal model faithfully replicates the myriad of symptoms seen in the clinical condition of MS. CPZ ingestion causes mitochondrial and endoplasmic reticulum stress and subsequent apoptosis of oligodendrocytes leads to central nervous system demyelination and glial cell activation. Although there are a wide variety of behavioural tests available for characterizing the functional deficits in animal models of disease, including that of CPZ-induced deficits, they have focused on a narrow subset of outcomes such as motor performance, cognition, and anxiety. The literature has not been systematically reviewed in relation to these or other symptoms associated with clinical MS. This paper reviews these tests and makes recommendations as to which are the most important in order to better understand the role of this model in examining aspects of demyelinating diseases like MS.

Can Neonatal Systemic Inflammation and Hypoxia Yield a Cerebral Palsy-Like Phenotype in Periadolescent Mice?

Cerebral palsy (CP) is one of the most common childhood-onset motor disabilities, attributed to injuries of the immature brain in the foetal or early postnatal period. The underlying mechanisms are poorly understood, rendering prevention and treatment strategies challenging. The aim of the present study was to establish a mouse model of CP for preclinical assessment of new interventions. For this purpose, we explored the impact of a double neonatal insult (i.e. systemic inflammation combined with hypoxia) on behavioural and cellular outcomes relevant to CP during the prepubertal to adolescent period of mice. Pups were subjected to intraperitoneal lipopolysaccharide (LPS) injections from postnatal day (P) 3 to P6 followed by hypoxia at P7. Gene expression analysis at P6 revealed a strong inflammatory response in a brain region-dependent manner. A comprehensive battery of behavioural assessments performed between P24 and P47 showed impaired limb placement and coordination when walking on a horizontal ladder in both males and females. Exposed males also displayed impaired performance on a forelimb skilled reaching task, altered gait pattern and increased exploratory activity. Exposed females showed a reduction in grip strength and traits of anxiety-like behaviour. These behavioural alterations were not associated with gross morphological changes, white matter lesions or chronic inflammation in the brain. Our results indicate that the neonatal double-hit with LPS and hypoxia can induce subtle long-lasting deficits in motor learning and fine motor skills, which partly reflect the symptoms of children with CP who have mild gross and fine motor impairments.

Stroke Longitudinal Volumetric Measures Correlate with the Behavioral Score in Non-Human Primates

Stroke is the second leading cause of death worldwide. Brain imaging data from experimental rodent stroke models suggest that size and location of the ischemic lesion relate to behavioral outcome. However, such a relationship between these two variables has not been established in Non-Human Primate (NHP) models. Thus, we aimed to evaluate whether size, location, and severity of stroke following controlled Middle Cerebral Artery Occlusion (MCAO) in NHP model correlated to neurological outcome. Forty cynomolgus macaques underwent MCAO, after four mortalities, thirty-six subjects were followed up during the longitudinal study. Structural T2 scans were obtained by magnetic resonance imaging (MRI) prior to, 48 h, and 30 days post-MCAO. Neurological function was assessed with the Non-human Primate Stroke Scale (NHPSS). T2 whole lesion volume was calculated per subject. At chronic stages, remaining brain volume was computed, and the affected hemisphere parceled into 50 regions of interest (ROIs). Whole and parceled volumetric measures were analyzed in relation to the NHPSS score. The longitudinal lesion volume evaluation showed a positive correlation with the NHPSS score, whereas the remaining brain volume negatively correlated with the NHPSS. Following ROI parcellation, NHPSS outcome correlated with frontal, temporal, occipital, and middle white matter, as well as the internal capsule, and the superior temporal and middle temporal gyri, and the caudate nucleus. These results represent an important step in stroke translational research by demonstrating close similarities between the NHP stroke model and the clinical characteristics following a human stroke and illustrating significant areas that could represent targets for novel neuroprotective strategies.

Liquefaction of the Brain following Stroke Shares a Similar Molecular and Morphological Profile with Atherosclerosis and Mediates Secondary Neurodegeneration in an Osteopontin-Dependent Mechanism

Here we used mouse models of heart and brain ischemia to compare the inflammatory response to ischemia in the heart, a protein rich organ, to the inflammatory response to ischemia in the brain, a lipid rich organ. We report that ischemia-induced inflammation resolves between one and four weeks in the heart compared to between eight and 24 weeks in the brain. Importantly, we discovered that a second burst of inflammation occurs in the brain between four and eight weeks following ischemia, which coincided with the appearance of cholesterol crystals within the infarct. This second wave shares a similar cellular and molecular profile with atherosclerosis and is characterized by high levels of osteopontin (OPN) and matrix metalloproteinases (MMPs). In order to test the role of OPN in areas of liquefactive necrosis, OPN^-/- mice were subjected to brain ischemia. We found that at seven weeks following stroke, the expression of pro-inflammatory proteins and MMPs was profoundly reduced in the infarct of the OPN^-/- mice, although the number of cholesterol crystals was increased. OPN^-/- mice exhibited faster recovery of motor function and a higher number of neuronal nuclei (NeuN) positive cells in the peri-infarct area at seven weeks following stroke. Based on these findings we propose that the brain liquefies after stroke because phagocytic cells in the infarct are unable to efficiently clear cholesterol rich myelin debris, and that this leads to the perpetuation of an OPN-dependent inflammatory response characterized by high levels of degradative enzymes.

Alzheimer's associated amyloid and tau deposition co-localizes with a homeostatic myelin repair pathway in two mouse models of post-stroke mixed dementia

The goal of this study was to determine the chronic impact of stroke on the manifestation of Alzheimer’s disease (AD) related pathology and behavioral impairments in mice. To accomplish this goal, we used two distinct models. First, we experimentally induced ischemic stroke in aged wildtype (wt) C57BL/6 mice to determine if stroke leads to the manifestation of AD-associated pathological β-amyloid (Aβ) and tau in aged versus young adult wt mice. Second, we utilized a transgenic (Tg) mouse model of AD (hAPP-SL) to determine if stroke leads to the worsening of pre-existing AD pathology, as well as the development of pathology in brain regions not typically expressed in AD Tg mice. In the wt mice, there was delayed motor recovery and an accelerated development of cognitive deficits in aged mice compared to young adult mice following stroke. This corresponded with increased brain atrophy, increased cholinergic degeneration, and a focal increase of Aβ in areas of axonal degeneration in the ipsilateral hemisphere of the aged animals. By contrast, in the hAPP-SL mice, we found that ischemia induced aggravated behavioral deficits in conjunction with a global increase in Aβ_, tau, and cholinergic pathology compared to hAPP-SL mice that underwent a sham stroke procedure. With regard to a potential mechanism, in both models, we found that the stroke-induced Aβ and tau deposits co-localized with increased levels of β-secretase 1 (BACE1), along with its substrate, neuregulin 1 (NGR1) type III, both of which are proteins integral for myelin repair. Based on these findings, we propose that the chronic sequelae of stroke may be ratcheting-up a myelin repair pathway, and that the consequent increase in BACE1 could be causing an inadvertent cleavage of its alternative substrate, AβPP, resulting in greater Aβ seeding and pathogenesis.

Effects of Danhong Injection (丹红注射液) and its main components on anticoagulation and fibrinolysis in cultured vein endothelial cells

OBJECTIVE

To observe the effects of Danhong Injection (丹红注射液) and its main components, including daiclzein and hydroxysafflor yellow A (HSYA), on the anticoagulation, fibrinolysis, anti-apoptosis in hypoxia model of vein endothelial cells (VECs).

METHODS

VECs were prepared and were put in a hypoxia environment, which consisted of mixed gas of 95% N and 5% CO mixed gas, when reached confluent culture. Five groups used different treatments, including normal control group, hypoxia group, daiclzein group, HSYA group and Danhong Injection group. The VECs were identified by fluorescence double labeling methods. The morphology was observed by a phase contrast microscopy. The effects of Danhong Injection, daiclzein and HSYA on 6 keto prostaglandin F1α (6-keto-PGF1α) level was measured by the method of radioimmunoassay (RIA). Superoxide dismutase (SOD) activity was tested by water soluble tetrazolium salt. The content of malondialdehyde (MDA) was measured by thiobarbituric acid. The activities of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) were measured by the method of chromogenic substrate. The contents of endothelin (ET) and nitric oxide (NO) were detected by non-equilibrium RIA and enzymelinked immunosorbent assay. Cells apoptosis rate was determined by flow cytometry.

RESULTS

Compared with the normal control group, the floating cells number, PAI activity, ET and MDA contents, and cells apoptosis rate in the culture solution of hypoxia group were all significantly increased, whereas the 6-keto-PGF1α and NO contents, and t-PA and SOD activities were decreased significantly (P<0.01). Compared with the hypoxia group, Danhong Injection markedly increased the 6-keto-PGF1α content and SOD activity, regulated PAI and t-PA activities, ET and NO contents, and decreased MDA content and cells apoptosis rate (P<0.05 or P<0.01).

CONCLUSIONS

Danhong Injection and its main components played an important role in protecting primary VECs from hypoxic damage by regulating the secretion and vasomotor function of VECs. The function of Danhong Injection was most remarkable.

Enriched Environment Enhances Poststroke Neurological Function Recovery on Rat: Involvement of p-ERK1/2

BACKGROUND

Increasing evidence shows that exposure to an enriched environment (EE) after cerebral ischemia or reperfusion injury is neuroprotective in animal models, including that EE enhances functional recovery after ischemic stroke. However, the mechanism underlying this effect remains unclear. To clarify this critical issue, the current study investigated the effects of EE on the role of extracellular signal-regulated kinase (ERK) after cerebral ischemia or reperfusion injury of rat.

METHODS

Adult rats were subjected to ischemia induced by middle cerebral artery occlusion (MCAO) followed by reperfusion. Ladder walking task and limb-use asymmetry task were used to test the recovery of rat behavior on postoperative days 1, 3, 5, 7, 14 and days 3, 7, 14, respectively. On the eighth day after MCAO, infarct volume was assessed by 2,3,5-triphenyltetrazolium chloride staining. Expressions of phosphorylated ERK1/2 (p-ERK1/2) and total ERK1/2 were examined by western blot, and electron microscopy was used to evaluate the astrocytes morphology surround in the perivascular 14 days after MCAO.

RESULTS

EE improves the recovery of coordination and integration of motor movements on rats after cerebral ischemia or reperfusion injury. EE downregulates the level of p-ERK1/2 in the rat cortex after cerebral ischemia or reperfusion injury. Furthermore, EE reduces astrocytic swelling and injury.

CONCLUSIONS

These findings suggest that EE could promote rehabilitation after ischemia via regulation of p-ERK1/2 expression, which may provide a therapeutic approach for cerebral ischemia or reperfusion injury. The suppression of postischemic astrocytic swelling in the brain of the ischemic rats through the intervention of EE would be one of the underlying mechanisms in the protective effect of cerebral ischemia.

Elevated body swing test after focal cerebral ischemia in rodents: methodological considerations

Background

The elevated body swing test (EBST) is a behavioral test used to evaluate experimental stroke in rodents. The basic idea is that when the animal is suspended vertically by the tail, it will swing its head laterally to the left or right depending on lesion side. In a previous study from our lab using the EBST after middle cerebral artery occlusion (MCAo), rats swung contralateral to the infarct day 1 post-MCAo, but ipsilateral day 3 post-MCAo. This shift was unexpected and prompted us to perform the present study. First, the literature was systematically reviewed to elucidate whether a similar shift had been noticed before, and if consensus existed regarding swing direction. Secondly, an experiment was conducted to systematically investigate the suggested behavior. Eighty-three adult male and female Sprague–Dawley rats were subjected to MCAo or sham surgery and the EBST was performed up to 7 days after the lesion.

Results

Both experimentally and through systematic literature review, the present study shows that the direction of biased swing activity in the EBST for rodents after cerebral ischemia can differ and even shift over time in some situations. The EBST curve for females was significantly different from that of males after the same occlusion time (p = 0.023).

Conclusions

This study highlights the importance of adequate reporting of behavioral tests for lateralization and it is concluded that the EBST cannot be recommended as a test for motor asymmetry after MCAo in rats.

Stroke in Saudi Arabia: a review of the recent literature

Stroke is a major cerebrovascular disease resulting in high mortality and persistent disability in adults across the world. Besides coronary heart disease and cancer, stroke is the commonest cause of death in most industrialized countries. Survivors of stroke are often left with severe mental and physical disabilities, which create a major social and economic burden, ranking as the second most common cause of death worldwide and a major source of morbidity. The Kingdom of Saudi Arabia (KSA) is the largest country in the Middle East occupying approximately four-fifths of the Arabian Peninsula supporting a population of more than 28 million. Stroke is becoming a rapidly increasing problem and an important cause of illness and deaths in Saudi Arabia. However, compared with the developed countries, research regarding the incidence, prevalence and their socio-demographic properties of stroke is still insufficient due to lack of appropriate studies being conducted in these specified areas. This review aims to discuss the range of the aspect of stroke in Saudi Arabia from the literature published.