A reproducible Endothelin-1 model of forelimb motor cortex stroke in the mouse

• Published in: Journal of neuroscience methods 2014-08, Vol.233, p.34-44
• Main Authors: Roome, R. Brian, Bartlett, Robert F., Jeffers, Matthew, Xiong, Jieying, Corbett, Dale, Vanderluit, Jacqueline L.
• Format: Article
• Language: English
• Subjects: Animals; Behavioral test; Brain Ischemia - complications; Brain Ischemia - pathology; Brain Ischemia - physiopathology; Cell Count; Cylinder test; Disease Models, Animal; Endothelin-1; Forelimb - physiopathology; Forelimb motor cortex; Immunohistochemistry; Injury volume; Male; Mice; Motor Cortex - pathology; Motor Cortex - physiopathology; Movement Disorders - etiology; Movement Disorders - pathology; Movement Disorders - physiopathology; Neural precursor cells; Neurons - pathology; Neurons - physiology; Random Allocation; Reproducibility of Results; Severity of Illness Index; Staircase test; Stroke - complications; Stroke - pathology; Stroke - physiopathology; Subventricular zone
• ISSN: 0165-0270; 1872-678X
• DOI: 10.1016/j.jneumeth.2014.05.014

•Intra-cortical injections of Endothelin-1 generate a reproducible ischemic injury.•Infarcts targeted to the anterior FMC result in consistent behavioral deficits.•Paw-dragging is a novel analysis of the mouse cylinder test.•Paw-dragging is a highly sensitive measure of forelimb motor cortex damage. Despite the availability of numerous transgenic mouse lines to study the role of individual genes in promoting neural repair following stroke, few studies have availed of this technology, primarily due to the lack of a reproducible ischemic injury model in the mouse. Intracortical injections of Endothelin-1 (ET1) a potent vasoconstrictive agent, reliably produces focal infarcts with concomitant behavioral deficits in rats. In contrast, ET1 infarcts in mice are significantly smaller and do not generate consistent behavioral deficits. We have modified the ET1 ischemia model to target the anterior forelimb motor cortex (aFMC) and show that this generates a reproducible focal ischemic injury in mice with consistent behavioral deficits. Furthermore, we have developed a novel analysis of the cylinder test by quantifying paw-dragging behavior. ET1 injections which damage deep layer neurons in the aFMC generate reproducible deficits on the staircase test. Cylinder test analysis showed no forelimb asymmetry post-injection; however, we observed a novel paw-dragging behavior in mice which is a positive sign of damage to the FMC. Previous ET1 studies have demonstrated inconsistent behavioral deficits; however, targeting ET1 injections to the aFMC reliably results in staircase deficits. We show that analysis of paw-dragging behavior in the cylinder test is a more sensitive measure of damage to the FMC than the classical forelimb asymmetry analysis. We have developed a focal ischemic injury model in the mouse that results in reproducible behavioral deficits and can be used to test future regenerative therapies.