Expression of damage-induced neuronal endopeptidase (DINE) mRNA in peri-infarct cortical and thalamic neurons following middle cerebral artery occlusion

Damage-induced neuronal endopeptidase (DINE) is a unique nerve-injury associated molecule, which was recently identified in a peripheral nerve injury model. The aim of this study was to determine the expression profiles and distribution of DINE in adult rats after middle cerebral artery (MCA) occlusion. Focal cerebral ischemia induced late-onset and prolonged expression of DINE mRNA in the peri-infarct cortex and specific nuclei of thalamus. Double labeling using immunohistochemistry and in situ hybridization revealed that DINE mRNA was exclusively expressed in cells that were positive to a neuronal marker NeuN. Previously established knowledge on neuroanatomical fiber connection suggests that DINE mRNA was expressed in areas projecting their axons to or through the core region of the infarction. This unique expression profile was similar to that of activating transcription factor-3 (ATF-3), which is a marker of nerve-injured neuron. More than 98% of ATF-3 immunoreactive neurons simultaneously expressed DINE mRNA, suggesting that DINE expression is observed in injured neurons of CNS as well as PNS. Since DINE expression promotes antioxidant activity, our results suggest that DINE may act as a neuroprotective molecule in neurons under ischemic insult.