Intranasal Calcitonin Gene-Related Peptide Protects Against Focal Cerebral Ischemic Injury in Rats Through the Wnt/β-Catenin Pathway

BACKGROUND: Intranasal calcitonin gene-related peptide (CGRP) delivery offers a noninvasive method of bypassing the blood-brain barrier for the delivery of CGRP to the brain. Here, we first reported the therapeutic benefits of intranasal CGRP delivery in rats following middle cerebral artery occlusion (MCAO). MATERIAL/METHODS: Real-time quantitative polymerase chain reaction (RT-qPCR) assay, enzyme-linked immunosorbent assay (ELISA), rat MCAO model, TTC (2, 3, 5-triphenyltetrazolium chloride) staining, hematoxylin and eosin (H & E) staining, Morris water maze test, TUNEL assay, immunofluorescence, and western blot assay were used to investigate the role of CGRP in rats. Cell Counting Kit-8 assay, colony formation assay, cell cycle assay, apoptosis assay, western blot assay, and TOP/FOP assay were used to investigate the role of CGRP in normal human astrocytes (NHA) cells. RESULTS: The CGRP-MCAO-NDDS (nasal drug delivery system) group showed a significant reduction in the infarct volume and improvement in neurologic deficit tests of motor, sensory, reflex and vestibulo-motor functions compared to those rats in the CGRP-MCAO-IV group. CGRP markedly inhibited apoptosis and increased the expression of vascular endothelial growth factor (VEGF) and bFGF and decreased the expression of GAP43 in the cortex of MCAO rats. CGRP promoted cell proliferation and cell cycle process and inhibited cell apoptosis through the Wnt/β-catenin pathway in NHA cells. CONCLUSIONS: This noninvasive, simple, and cost-effective method is a potential treatment strategy for focal cerebral ischemic injury.