Decreased expression of insulin-like growth factor binding protein 2 in the prefrontal cortex of subjects with bipolar disorder and its regulation by lithium treatment

Insulin-like growth factors (IGFs) regulate cellular proliferation and death, and their bioactivity is controlled by IGF binding proteins (IGFBPs). Since IGFBP-2 is the major brain resident IGFBP, and we have demonstrated lithium-mediated changes in its mRNA and protein levels in neuronal cultures, we examined IGFBP-2 expression in prefrontal cortex postmortem brain tissue from subjects with mood disorders. We found decreased IGFBP-2 expression in bipolar disorder patients compared with controls; this was especially pronounced in subjects not treated with lithium. These results suggest a role for IGFBPs in the etiology and pharmacotherapy of mood disorders.