Abstract
Glucagon-like peptide-1 (7-36)-amide (GLP-1) is an endogenous 30-amino acid gut peptide, which binds at the GLP-1 receptor coupled to the cyclic AMP second messenger pathway. GLP-1 receptor stimulation enhances pancreatic islet β-cell proliferation, glucose-dependent insulin secretion and lowers blood glucose and food intake in patients with type 2 diabetes mellitus. Not limited to the pancreas, the chemoarchitecture of GLP-1 receptor distribution in the brain of rodents and humans correlates with a central role for GLP-1 in the regulation of food intake. However emerging evidence suggests that stimulation of neuronal GLP-1 receptors plays an important role in regulating neuronal plasticity and cell survival. GLP-1 has been documented to induce neurite outgrowth and to protect against excitotoxic cell death and oxidative injury in cultured neuronal cells. Moreover, GLP-1 and exendin-4, a naturally occurring more stable analogue of GLP-1 that likewise binds at the GLP-1 receptor, were shown to reduce endogenous levels of amyloid-β peptide (Aβ) in mouse brain and to reduce levels of β-amyloid precursor protein (βAPP) in neurons. Collectively these data suggest that treatment with GLP-1 or a related peptide beneficially affects a number of the therapeutic targets associated with Alzheimers disease (AD). Although much remains to be elucidated with regards to the downstream signaling pathways involved in the pro-survival properties of GLP-1, modulation of calcium homeostasis may be critical. This review will consider the potential therapeutic relevance of GLP-1 to CNS disorders, such as AD.
Keywords: apoptosis, cyclic amp, diabetes, excitotoxicity, insulinotropic, neurodegeneration, synaptic plasticity
16