A Temporal MRI Assessment of Neuropathology after Transient Middle Cerebral Artery Occlusion in the Rat: Correlations with Behavior

The purpose of this study was to evaluate the temporal and spatial pathological alterations within ischemic tissue using serial magnetic resonance imaging (MRI) and to determine the extent and duration of functional impairment using objective behavioral tests after transient middle cerebral artery occlusion (tMCAO) in the rat. MRI signatures derived from specific anatomical regions of interest (ROI) were then appropriately correlated to the behavioral measures over the time course of the study (up to 28 days post-tMCAO). Sprague-Dawley rats (n = 12) were initially trained on the following behavioral tasks before surgery: bilateral sticky label test (for contralateral neglect); beam walking (for hindlimb coordination); staircase test (for skilled forelimb paw-reaching). Rats were then randomly assigned to receive either tMCAO (90 minutes, n = 6), by means of the intraluminal thread technique, or sham-control surgery (n = 6). Proton density, T2- and T2-diffusion-weighted MR images were acquired at 1, 7, 14, and 28 days post-tMCAO that were then smoothed into respective proton density, T2 relaxation, and apparent diffusion coefficient (ADC) maps. Apparent percent total lesion volume was assessed using T2W imaging. MR signatures were evaluated using the tissue maps by defining ROI for MCAO and sham-control groups, which corresponded to the caudate-putamen, forelimb, hindlimb, and lower parietal cortices both ipsilateral and contralateral to the occlusion site. Behavioral tests were undertaken daily from 1 to 28 days post-tMCAO. Results demonstrate that apparent percent lesion volume reduced from 1 to 7 days ( P < 0.05) but then remained constant up to 28 days for the MCAO group. Pathological changes in the temporal profile of T2 and ADC tissue signatures were significantly altered in specific ROI across the time course of the study ( P < 0.05 to < 0.001), reflecting the progression of edema to necrosis and cavitation. Both T2 and ADC measures of ischemic pathology correlated with parameters defined by each of the functional tests ( r ≥0.5, P < 0.05) across the time course. The staircase test revealed bilateral impairments for the MCAO group ( P < 0.001), which were best predicted by damage to the ipsilateral lower parietal cortex by means of hierarchical multiple regression analyses ( R2 changes ≥0.21, P < 0.03). Behavioral recovery was apparent on the beam walking test at 14 to 28 days post-MCAO, which was mirrored by MRI signatures within the hindlimb cortex returning to sham-control levels. This long-term study is the first of its kind in tracing the dynamic pathologic and functional consequences of tMCAO in the rat. Both serial MRI and objective behavioral assessment provide highly suitable outcome measures that can be effectively used to evaluate promising new antiischemic agents targeted for the clinic.

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Reliability of behavioral tests in the middle cerebral artery occlusion model of rat

Laboratory Animals ◽

10.1177/0023677218815210 ◽

2018 ◽

Vol 53 (5) ◽

pp. 478-490 ◽

Cited By ~ 3

Author(s):

Junghoon Yu ◽

Jinkyoo Moon ◽

Joonyoung Jang ◽

Jee In Choi ◽

Jooeun Jung ◽

...

Keyword(s):

Middle Cerebral Artery ◽

Middle Cerebral Artery Occlusion ◽

Cerebral Artery ◽

Rat Model ◽

Artery Occlusion ◽

Behavioral Tests ◽

Walking Test ◽

Satisfactory Level ◽

Cylinder Test ◽

Cerebral Artery Occlusion

Stroke is one of the leading causes of death and disability worldwide, and its incidence is increasing. To overcome impairment from stroke, translational research for developing new therapeutic technologies has been conducted and middle cerebral artery occlusion (MCAo) in rat is the representative model. Since recovery from neurological impairment in contralateral limbs caused by brain damage is the major goal of treatment, behavioral tests that assess the relevant function are used. To determine therapeutic effect, obtaining reliable results of behavioral assessment is a prerequisite. However, studies on the reliability of behavioral tests in the MCAo rat model and necessity of prior training have not yet been reported. In this study, the authors investigate relative and absolute inter-rater reliabilities of modified neurological severity score (mNSS), cylinder test, and grid-walking test before training and repeated training every week until the reliability of results reached a satisfactory level. The training included repeated learning of the scoring system and decreasing disagreements among the raters. For MCAo modeling, adult male Sprague-Dawley rats were subjected to 90 min of transient MCAo. Six raters conducted behavioral tests via observation of video-recording on sham-operated and MCAo model rats at 3 or 7 days after the intervention. An independent experimenter randomly numbered each video clip to blind the experiment. The results of reliabilities were unacceptable before training and improved to a satisfactory level after 6 weeks of training in all of the tests. In conclusion, mNSS, cylinder test, and grid-walking test on the MCAo rat model are reliable evaluation methods after conducting appropriate training.

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Prediction of secondary ischemic lesions with diffusion-weighted imaging after transient middle cerebral artery occlusion in rats

Stroke ◽

10.1161/str.32.suppl_1.352-d ◽

2001 ◽

Vol 32 (suppl_1) ◽

pp. 352-352

Author(s):

Fuhai Li ◽

Matthew D Silva ◽

Xiangjun Meng ◽

Christopher H Sotak ◽

Marc Fisher

Keyword(s):

Middle Cerebral Artery ◽

Middle Cerebral Artery Occlusion ◽

Cerebral Artery ◽

Diffusion Weighted Imaging ◽

Artery Occlusion ◽

Lesion Volume ◽

Diffusion Weighted ◽

Adc Values ◽

Cerebral Artery Occlusion ◽

Initial Lesions

P75 Background and Purpose: Previous studies demonstrated that secondary ischemic lesions documented by diffusion-weighted imaging might be smaller than, larger than or similar to initial lesions that occur during ischemia. The purpose of this study was to investigate if the size of secondary lesions can be predicted. Methods: Twelve rats underwent 30 minutes of transient middle cerebral artery occlusion with the intraluminal suture method. Diffusion- and perfusion-weighted images were performed just before reperfusion, 90 minutes and 24 hours after reperfusion. The ischemic lesion size was calculated by tracing visual abnormalities on the apparent diffusion coefficient (ADC) maps. Cerebral blood flow index (CBF i ) ratio was calculated by dividing the ipsilateral CBF i by the contralateral CBF i . Based on difference between initial and secondary lesion volume, rats were assigned to reperfusion-benefit group (n=6) where secondary lesions were smaller than initial lesions (less than 85% of initial lesions) and reperfusion-nonbenefit group (n=6) where secondary lesions were similar to or larger than initial lesions (more than 85% of initial lesions). Results: At 90 minutes after reperfusion, the initial ischemic lesions almost disappeared in both groups. At 24 hours, secondary lesions were 54±11% (mean±SD) of the initial lesions in the reperfusion-benefit group and 100±14% of the initial lesions in the reperfusion-nonbenefit group (p<0.001). There was no difference in ADC values (47±2×10 -5 mm 2 /s vs 46±5×10 -5 mm 2 /s, p=0.7) and CBF i ratio (0.62±0.06 vs 0.67±0.04, p=0.2) between the two groups before reperfusion. However, the initial lesion volume was significantly smaller in the reperfusion-benefit group than in the reperfusion-nonbenefit group (125±54 mm 3 vs 195±36 mm 3 , p=0.037). Conclusions: Changes of ADC values and CBF before reperfusion are unable to predict if initial ischemic lesions will eventually shrink or not after reperfusion. Smaller size of initial lesions may suggest that secondary lesions will be smaller than initial lesions.

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Adenosine A1R/A3R (Adenosine A1 and A3 Receptor) Agonist AST-004 Reduces Brain Infarction in a Nonhuman Primate Model of Stroke

Stroke ◽

10.1161/strokeaha.121.036396 ◽

2021 ◽

Author(s):

Theodore E. Liston ◽

Aldric Hama ◽

Johannes Boltze ◽

Russell B. Poe ◽

Takahiro Natsume ◽

...

Keyword(s):

Middle Cerebral Artery ◽

Middle Cerebral Artery Occlusion ◽

Cerebral Artery ◽

Artery Occlusion ◽

Lesion Volume ◽

Nonhuman Primate Model ◽

Primate Model ◽

Adenosine A1 ◽

Lesion Growth ◽

Cerebral Artery Occlusion

Background and Purpose: Treatment with A1R/A3R (adenosine A1 and A3 receptor) agonists in rodent models of acute ischemic stroke results in significantly reduced lesion volume, indicating activation of adenosine A1R or A3R is cerebroprotective. However, dosing and timing required for cerebroprotection has yet to be established, and whether adenosine A1R/A3R activation will lead to cerebroprotection in a gyrencephalic species has yet to be determined. Methods: The current study used clinical study intervention timelines in a nonhuman primate model of transient, 4-hour middle cerebral artery occlusion to investigate a potential cerebroprotective effect of the dual adenosine A1R/A3R agonist AST-004. Bolus and then 22 hours intravenous infusion of AST-004 was initiated 2 hours after transient middle cerebral artery occlusion. Primary outcome measures included lesion volume, lesion growth kinetics, penumbra volume as well as initial pharmacokinetic-pharmacodynamic relationships measured up to 5 days after transient middle cerebral artery occlusion. Secondary outcome measures included physiological parameters and neurological function. Results: Administration of AST-004 resulted in rapid and statistically significant decreases in lesion growth rate and total lesion volume. In addition, penumbra volume decline over time was significantly less under AST-004 treatment compared with vehicle treatment. These changes correlated with unbound AST-004 concentrations in the plasma and cerebrospinal fluid as well as estimated brain A1R and A3R occupancy. No relevant changes in physiological parameters were observed during AST-004 treatment. Conclusions: These findings suggest that administration of AST-004 and combined A1R/A3R agonism in the brain are efficacious pharmacological interventions in acute ischemic stroke and warrant further clinical evaluation.

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A review of experimental models of focal cerebral ischemia focusing on the middle cerebral artery occlusion model

F1000Research ◽

10.12688/f1000research.51752.2 ◽

2021 ◽

Vol 10 ◽

pp. 242

Author(s):

Melissa Trotman-Lucas ◽

Claire L. Gibson

Keyword(s):

Ischemic Stroke ◽

Middle Cerebral Artery ◽

Middle Cerebral Artery Occlusion ◽

Cerebral Artery ◽

Artery Occlusion ◽

Lesion Volume ◽

Mechanistic Investigation ◽

Cerebral Artery Occlusion

Cerebral ischemic stroke is a leading cause of death and disability, but current pharmacological therapies are limited in their utility and effectiveness. In vitro and in vivo models of ischemic stroke have been developed which allow us to further elucidate the pathophysiological mechanisms of injury and investigate potential drug targets. In vitro models permit mechanistic investigation of the biochemical and molecular mechanisms of injury but are reductionist and do not mimic the complexity of clinical stroke. In vivo models of ischemic stroke directly replicate the reduction in blood flow and the resulting impact on nervous tissue. The most frequently used in vivo model of ischemic stroke is the intraluminal suture middle cerebral artery occlusion (iMCAO) model, which has been fundamental in revealing various aspects of stroke pathology. However, the iMCAO model produces lesion volumes with large standard deviations even though rigid surgical and data collection protocols are followed. There is a need to refine the MCAO model to reduce variability in the standard outcome measure of lesion volume. The typical approach to produce vessel occlusion is to induce an obstruction at the origin of the middle cerebral artery and reperfusion is reliant on the Circle of Willis (CoW). However, in rodents the CoW is anatomically highly variable which could account for variations in lesion volume. Thus, we developed a refined approach whereby reliance on the CoW for reperfusion was removed. This approach improved reperfusion to the ischemic hemisphere, reduced variability in lesion volume by 30%, and reduced group sizes required to determine an effective treatment response by almost 40%. This refinement involves a methodological adaptation of the original surgical approach which we have shared with the scientific community via publication of a visualised methods article and providing hands-on training to other experimental stroke researchers.

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