Rapid antidepressive-like activity of specific glycogen synthase kinase-3 inhibitor and its effect on β-catenin in mouse hippocampus

Background: Inhibition of glycogen synthase kinase-3 (GSK-3) is thought to be a key feature in the therapeutic mechanism of several mood stabilizers; however, the role of GSK-3 in depressive behavior has not been determined. In these studies, we evaluated the antidepressive effect of L803-mts, a novel GSK-3peptide inhibitor, in an animal model of depression, the mouseforced swimming test (FST). Methods: Animals were intracerebroventricularly injected with L803-mts or witb respective control peptide (cp) 1 hour, 3 bours, or 12 hours before their subjection to FST. Results: Animals administered L803-mts showed reduced duration of immobility at all three time points tested, as compared with cp-treated animals. Expression levels of beta-catenin, the endogenous substrate of GSK-3, increased in the hippocampus of L803-mts-treated animals by 20%-50%, as compared with cp-treated animals. Conclusions: Our studies show, for the first time, that in-vivo inhibition of GSK-3 produces antidepressive-like behavior and suggest the potential of GSK-3 inhibitors as antidepressants.