Introduction:
Manual scoring of behavior tests is commonly used for assessing motor deficits after stroke, however, it is labor intensive and subject to bias. These limitations lead to inconsistent assessment between research groups and non-reproducible data. In this study, we investigated the feasibility of an automated motor deficit assessment system, Erasmus ladder, in two ischemic stroke models.
Methods:
Distal middle cerebral artery occlusion (dMCAO n=10) or transient middle cerebral artery occlusion (tMCAO 30 minutes, n=15) were performed on male C57BL6J mice (11-13 weeks) to generate cortical ischemic stroke, with. Naïve mice (n=10) were used as controls. Immunohistochemistry was performed on brains collected at post-stroke day (PD) 30 to assess for infarct size (MAP2) and inflammation (CD68). Mice without infarct in both cortex and striatum were excluded from the study. Behavior was assessed using Erasmus ladder at pre-stroke baseline (4 unperturbed and 4 perturbed sessions) and on PD 7, 14, 21, and 28 (all perturbed sessions).
Results:
Erasmus ladder detected significant motor deficits in the tMCAO model, specifically in the pre- and post- perturbed times as well as several key step types (HH long). Analyses in the tMCAO model reveal changes in various step patterns and their capability to react to the perturbation (obstacle). These significant motor deficits after tMCAO were detectable until PD28. We also observed a sustained decline in the use of affected limb compared to unaffected limb until PD28. While this trend is also present in dMCAO model, motor deficits were detected in the dMCAO only at early timepoints (PD7) and the difference subsided by PD28.
Conclusion:
We have assessed the data collected by Erasmus ladder on mice that underwent two commonly used stroke models (tMCAO and dMCAO). Our data showed that Erasmus ladder can detect long term motor deficit including reduced use of affected limb, step pattern, and motor reaction to obstacle. This automated instrument is effective in detecting motor deficits in the tMCAO model and thus, can be used to evaluate treatments for enhancing recovery after stroke.
Motor deficit in the mouse ferric chloride-induced distal middle cerebral artery occlusion model of stroke
