Pen1-XBIR3 is neuroprotective against cerebral ischemia. A, Intranasal Pen1-XBIR3 protects neurons. Vehicle or Pen1-XBIR3 was delivered, and rats were harvested at 12 hpr (left) and 24 hpr (right). Sections were immunostained for NeuN (green), and NeuN-positive cells were quantified. Epifluorescence microscopy was used. Scale bars, 50 μm. Graphs are means (with SEM) of axon counts and neuron counts at 12 hpr (left) and 24 hpr (right). Nonstroked, 494.7 ± 18.52, n = 3; vehicle-12hpr, 463.7 ± 57.53, n = 3; Pen1-XBIR3-12 hpr, 477.3 ± 28.95, n = 3; vehicle-24 hpr, 338.0 ± 22.91, n = 3; Pen1-XBIR3-24 hpr, 453.7 ± 25.44, n = 3 (ANOVA, *p < 0.05). B, Intranasal Pen1-XBIR3 reduces ischemic infarct volume. Vehicle or Pen1-XBIR3 was delivered as in A, and rats were harvested at 24 hpr. Sections were stained with H&E. Direct stroke volume (infarct area/ipsilateral hemisphere area) was quantified. Vehicle-24 hpr, 55.08 ± 3.546, n = 3; Pen1-XBIR3–24 hpr, 38.56 ± 4.749, n = 3 (ANOVA, p < 0.05). C, Intranasal Pen1-XBIR3 provides long-term protection from stroke. Two hour tMCAo was performed on rats given either prophylactic (prestroke) intranasal vehicle (black squares) or prophylactic Pen1-XBIR3 (blue triangles) or therapeutic (poststroke) Pen1-XBIR3 (red circles). Rats were monitored for 21 d. Means (with SEM) of neurofunctional score are shown. Control vehicle (green diamond) and Pen-XBIR3 (orange circle) animals displayed no loss of neurofunction. ANOVA is shown. Asterisks indicate stroked prophylactic vehicle versus prophylactic or therapeutic Pen1-XBIR3 (n = 8 per group, p < 0.05).