The dietary isothiocyanate sulforaphane reduces peri-infarct constriction frequency in mouse focal cerebral ischaemia via Nrf2-independent mechanisms

Excitotoxic dysfunction exacerbates ischaemic stroke pathology. CNS energy failure leads to ion transport dysregulation and uncontrolled depolarizations, which propagate across the surface of the ischemic cortex as waves. Repolarization taxes energy-deficient tissue, while ion flux drives peri-infarct vascular constrictions (PICs) and mitochondrial free radical production. Sulforaphane (SFN) is a dietary isothiocyanate and inducer of redox defences via the transcription factor Nrf2, previously shown to reduce infarct volume in mice and rats when given i.p. prior to stroke, but its mechanisms of action are still undefined. We quantified peri-infarct constriction waves in mice subjected to 60 min focal cerebral ischemia by laser speckle imaging of the intact skull. Dietary pre-treatment with 5 mg/kg SFN for 3 d reduced PIC incidence in both wild-type (3.66 ±0.21 to 2.00 ±2.00) and Nrf2-/- (4.25 ±0.25 to 1.33 ±0.33) 10-week old male mice, without altering other excitotoxic indices (time to first PIC, propagation speed), n=4–6, p