The Neuroprotective Effect of Liraglutide is Mediated by Glucagon-Like Peptide 1 Receptor-Mediated Activation of cAMP/PKA/CREB Pathway

Background/Aims: Glucagon-like peptide-1 (GLP-1)-based drugs are being used to achieve better glucose control in patients with type 2 diabetes, and GLP-1 mimetics such as liraglutide have shown therapeutic potential in preventing diabetes-related microvascular and macrovascular complications as well as comorbidities such as neurodegenerative disorders. In the present study, we investigated the effects of liraglutide on primary rat cortical astrocytes treated with advanced glycation end-products (AGEs). Methods: Gene and protein expression was analyzed by quantitative real time PCR, western blots, and enzyme-linked immunosorbent assay. The caspase-3 activity was assessed using a caspase-3 colorimetric assay kit. The ROS production was measured with CM-H2DCFDA staining. The cell viability of rat astrocytes was determined using MTT assay. Results: Liraglutide ameliorated AGEs-induced oxidative stress, inflammatory cytokine secretion, caspase activation, and cell death in astrocytes, and reversed the AGEs mediated reduction in intracellular cyclic AMP (cAMP) levels, protein kinase A (PKA) activity, and the phosphorylation of the cAMP response element-binding (CREB) protein. The protective effects of liraglutide against AGEs-mediated toxicity were abolished by GLP1 receptor (GLP-1R) knockdown or pretreatment of cells with the adenylyl cyclase inhibitor SQ22536 or the PKA inhibitor Rp-cAMP. Conclusions: Liraglutide exerts its neuroprotective effects via the GLP-1R-mediated activation of the cAMP/PKA/CREB pathway. The results of the present study support the therapeutic potential of liraglutide for the treatment of neurodegenerative disorders. Copyright (C) 2015 S. Karger AG, Basel