Selegiline promotes NOTCH-JAGGED signaling in astrocytes of the peri-infarct region and improves the functional integrity of the neurovascular unit in a rat model of focal ischemia.

Abstract

Our experiments aimed at exploring potential neurorestorative mechanisms of selegiline, a compound routinely used in the treatment of Parkinson's disease and previously shown to improve the functional recovery of stroke patients. Selegiline was administered continuously via osmotic mini-pumps between 48 and 216 hours following middle cerebral artery occlusion (MCAO) in rats. Twenty-four hours before sacrifice, the animals underwent magnetic resonance imaging (MRI). After decapitation, the peri-infarct region was dissected to perform a TAQMAN array gene expression study, and brains were fixed for immunolabeling. In addition to the previously known induction of anti-apoptosis genes, selegiline significantly increased the mRNA level of Notch 1 receptor and its ligand Jagged 1. Immunohistochemistry demonstrated elevated Notch 1 and Jagged 1 immunoreactivities in the peri-infarct region. Double labeling with glial markers revealed that both Notch 1 and Jagged 1 were expressed in astrocytes but not in microglia. MRI examination indicated significantly reduced edema in selegiline-treated rats compared to control MCAO rats, and increased capillary network density was found in the peri-infarct region of the selegiline-treated animals. Our results suggest that selegiline treatment enhances Notch-Jagged signaling in astrocytes, reduces peri-lesional edema and potentially helps preserve the capillary network following focal ischemia.