Effects of the glucagon-like polypeptide-1 analogue (Val8 )GLP-1 on learning, progenitor cell proliferation and neurogenesis in the C57B/16 mouse brain

• Published in: Brain research 2012-09, Vol.1473, p.204-213
• Main Authors: McGovern, Stephen F.J, Hunter, Kerry, Hölscher, Christian
• Format: Article
• Language: English
• Subjects: Adult and adolescent clinical studies; Alzheimer disease; Alzheimer's disease; Animals; antagonists; anxiety; Biological and medical sciences; blood glucose; blood-brain barrier; Blood-Brain Barrier - drug effects; brain; Brain - drug effects; cell proliferation; Cell Proliferation - drug effects; Cognition; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Diabetes; drugs; Enzyme-Linked Immunosorbent Assay; glucagon-like peptide 1; Glucagon-Like Peptide 1 - pharmacology; Immunohistochemistry; Incretin; Insulin; insulin resistance; Learning - drug effects; locomotion; Male; Medical sciences; memory; Mice; Mice, Inbred C57BL; Neural Stem Cells - drug effects; Neurodegenerative disease; Neurogenesis; Neurogenesis - drug effects; Neurology; noninsulin-dependent diabetes mellitus; Organic mental disorders. Neuropsychology; Peptide Fragments - pharmacology; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Rats; Rats, Sprague-Dawley; risk factors; stem cells
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2012.07.029

Abstract Type 2 diabetes (T2DM) has been identified as a risk factor for Alzheimer's disease. Here, we tested the properties of the glucagon-like polypetide-1 (GLP-1) analogue (Val8)GLP-1, a drug originally developed as a treatment for T2DM at a range of doses (2.5 nmol; 25 nmol; 100 nmol; or 250 nmol/kg bw ip.) in an acute memory study in wild type C57B/l6 mice. We also tested (Val8)GLP-1 and the GLP-1 receptor antagonist exendin (9–39) in a chronic study (3 weeks at 25 nmol/kg bw ip. once-daily). We found that (Val8)GLP-1 crossed the blood brain barrier readily and that peripheral injection increased levels in the brain 30 min post-injection ip. but not 2 h post-injection in rats. In the acute study, the low dose of 2.5 nmol/kg ip. enhanced motor activity in the open field task, while total distance travelled, exploratory behaviour and anxiety was not affected at any dose. Learning an object recognition task was not affected either. In the chronic study, no effect was observed in the open field assessment. The antagonist exendin (9–39) impaired object recognition learning and spatial learning in a water maze task, demonstrating the importance of GLP-1 signalling in memory formation. Locomotor activity was also affected in some cases. Blood sugar levels and insulin sensitivity was not affected in chronically treated mice. Neuronal stem cells and neurogenesis was enhanced by (Val8)GLP-1 in the dentate gyrus of wild type mice. The results demonstrate that (Val8)GLP-1 is safe in a range of doses, crosses the BBB and has potentially beneficial effects in the CNS by enhancing neurogenesis.