A Complete Guide to Using the Endothelin-1 Model of Stroke in Conscious Rats for Acute and Long-Term Recovery Studies

Abstract

Multiple methods exist to model permanent and transient ischemia under anesthesia in animals, however most human strokes occur while conscious. The use of endothelin-1 as a vasoconstrictor applied to the perivascular surface of the middle cerebral artery is one of the only methods for inducing stroke in conscious animals. Here, we describe standard operating procedures for stereotaxic placement of an ET-1 guide probe above the middle cerebral artery, induction of stroke in conscious rats, predictive outcome scoring during stroke, and neurological behavioral tests that we use to monitor transient and continuing deficits. The inclusion of long term neurological assessment is of particular importance when taking into consideration the effects of stroke on brain remodeling.

Blood–Brain Barrier Transporters: Opportunities for Therapeutic Development in Ischemic Stroke

“…When exogenously supplemented in high concentrations at the MCA, severe vasoconstriction leads to occluded blood flow and infarcted brain tissue similar to that observed in the setting of human stroke. Abeysinghe and Roulston report in a detailed protocol [189] that the surgery begins by anesthetizing the subject and mounting it onto a stereotaxic frame. The scalp is then exposed, allowing for positioning of screws and an injector guide cannula (some protocols, comparable to that reported by Ansari and colleagues [190], additionally mount a laser Doppler probe to measure the drop in blood flow during the ET-1 injection).…”

“…To induce the stroke in a freely moving animal, a microinjector is loaded with ET-1 solution, inserted into the guide cannula, and steadily released at the site of the MCA. Some behavioral measures to assess stroke outcome in the ET-1-induced stroke model include the neurological deficit score, sensorimotor hemineglect, rotarod motor performance, cylinder test, and staircase test [189].…”

“…Slower reperfusion more accurately represents the phenotype observed from natural thrombolysis [191]. Although this technique yields infarction volumes that are highly variable [190], some argue that this factor actually makes it a better system to model stroke due to the high variation of infarction volumes measured in human stroke patients [189]. Studies have demonstrated that the ischemic infarction generated from ET-1 also mimics stroke evolution in humans and, therefore, would be a reliable model for research on stroke therapeutics [192]; however, the lack of transporter studies in the ET-1 model makes it difficult to rely on it for drug research.…”

Optical Modalities for Research, Diagnosis, and Treatment of Stroke and the Consequent Brain Injuries

“…Development of a stroke-induced animal model for preclinical tests and modalities to build such an animal model are being extensively investigated [16][17][18][19]. A typical stroke animal model investigation is achieved either through surgical blocking of specific vessels [20][21][22] or through a biochemical method [23,24]. However, stroke in local brain regions is investigated using photochemical thrombosis.…”

Hemispheric cortical atrophy and chronic microglial activation following mild focal ischemic stroke in adult male rats

“…Up to 80% of silent brain infarcts have been demonstrated to be cortically located, especially in postsurgical, high vascular risk populations (Nah et al, 2014). Microinjection of the potent vasoconstrictor endothelin-1 has become a widely used approach to model focal ischemic injury in rodents with the capacity to modulate severity based on dosage (Abeysinghe & Roulston, 2018). We recently reported that ET-1 injection into the sensorimotor cortex of athymic rats that have a compromised immune system resulted in a focal ischemic injury associated with a stable motor impairment over 36 weeks (Ermine et al, 2019).…”