Reduced Cerebral Infarct Volume in Young UCP2^-/- Mice and Preserved Synaptic Transmission by Genipin

Cerebral ischemia-reperfusion injury is a key determinant of a poor outcome after stroke. The mitochondrial uncoupling protein 2 (UCP2) has been implicated in cerebral ischemia-reperfusion injury and in the outcome of ischemic stroke, although its role remains controversial. In C57BL/6J and B6.129S4-Ucp2^tm1Lowl/J (UCP2^-/-) mice, we analyzed cognitive function and lifespan. In an MCAO model induced for one hour, infarct volumes, neurological deficits, and gene expression patterns were determined after 24 h. The UCP2 inhibitor genipin was used in an oxygen-glucose deprivation (OGD) model to investigate synaptic transmission in the hippocampus. Compared to controls, UCP2^-/- mice exhibited a reduced lifespan and displayed impaired cognition. However, in 6-month-old UCP2^-/- mice, the infarct volume was reduced, primarily due to a smaller core size, but not in 18-month-old animals. In both strains, ischemia induced upregulation of antioxidant defense genes, including catalase and SOD1. In the ex vivo ODG model, synaptic transmission was depressed, but pretreatment with genipin prevented the tissue from this impairment. Our findings indicate an infarct-reducing effect of UCP2 deficiency, especially in young-adult mice, and, mechanistically, a neuroprotective effect by genipin in hippocampal slices.