Here, we tested the idea that mice with a PTHrP-null CNS might display hypersensitivity to kainic acid excitotoxicity. We found that these mice were six-fold more sensitive than control littermate mice to kainic-acid-induced seizures as well as hippocampal c-Fos expression.;Superfusion with PTHrP(1–34) peptide for up to 25 min increased pial arteriolar diameter by 30% in normal animals. In animals with permanent MCAO, PTHrP(1–34) peptide treatment significantly decreased cortical infarct size (47%).