Structure-Based Design Leads to the Identification of Lithium Mimetics That Block Mania-like Effects in Rodents. Possible New GSK-3β Therapies for Bipolar Disorders

More than two million American adults, or approximately one percent of the population 18 years or older, suffer from bipolar disorder. Current treatments include the so-called “mood stabilizers,” lithium and valproic acid. Both are relatively dated drugs that are only partially effective and produce various undesirable side effects including weight gain. Based upon continued efforts to understand the molecular target for lithium, it now appears that specific inhibitors of the enzyme glycogen synthase kinase-3β (GSK-3β) may mimic the therapeutic action of mood stabilizers and might therefore allow for the design of improved drugs for treating patients with bipolar disorder as well as certain neurodegenerative disorders. Furthermore, the pro-apoptotic properties of the GSK-3 enzyme suggest the possible use of such inhibitors as neuroprotective agents. In fact, neuroprotection may contribute to the treatment of mood disorders. The present chemistry, modeling, and biology efforts have identified 3-benzofuranyl-4-indolylmaleimides as potent and relatively selective GSK-3β inhibitors. The best ligand in this series (having a K_i value of 4.6 nM against GSK-3β) was studied in a novel mouse model of mania that has recently been validated with several clinically effective mood stabilizers. This study presents the first demonstration of the efficacy of a GSK-3β inhibitor in this mouse model of mania. Selective brain penetrable GSK-3 ligands like those described herein become valuable research tools in better defining the role of this multifaceted kinase in both physiological and pathophysiological events.