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-3 peptide inhibitor, in an animal model of depression, the mouse forced swimming test (FST).
Methods: Animals were intracerebroventricularly injected with L803-mts or with respective control peptide (cp) 1 hour, 3 hours, 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.