A pilot study on transient ischemic stroke induced with endothelin-1 in the rhesus monkeys

Endothelin-1 (ET-1), a vasoconstrictor, has recently been used to induce focal ischemia in rodents and marmoset monkeys. The rhesus monkey, however, has numerous advantages to the rodent and marmoset that make it a superior and irreplaceable animal model for studying stroke in the brain. In the present study, after mapping the preferred hand representation in two healthy male monkeys with intracortical micro-stimulation, ET-1 was microinjected into the contralateral motor cortex (M1) to its preferred hand. The monkeys had been trained in three manual dexterity tasks before the microinjection and were tested for these tasks following the ET-1 injection. Brain Magnetic Resonance Imaging scans were performed 1, 7, 14 and 28 days post ischemia. It was found that ET-1 impaired the manual dexterity of the monkeys in the vertical slot and rotating Brinkman board tasks 3-8 days after the injection. Brain imaging found that severe edema was present 7 days after the focal ischemia. This data suggest that ET-1 can induce transient ischemic stroke in rhesus monkey and that ET-1 induced focal ischemia in non-human primates is a potential model to study the mechanism of stroke and brain repair after stroke.