Decreased levels of whole blood glial cell line-derived neurotrophic factor (GDNF) in remitted patients with mood disorders

Recent post-mortem and imaging studies provide evidence for a glial reduction in different brain areas in mood disorders. This study was aimed to test whether glial cell line-derived neurotrophic factor (GDNF), a member of transforming growth factor (TGF)-beta superfamily, in blood levels was associated with mood disorders. We measured GDNF and TGF-beta levels in whole blood in remitted patients with mood disorders [n=56; major depressive disorders (MDD) 39, bipolar disorders (BD) 171 and control subjects (n=56). GDNF and TGF-beta were assayed with the sandwich ELISA method. Total GDNF levels were significantly lower in MDD and in BD than in control subjects (MDD, p=0.0003; BD, p=0.018), while no significant difference in total TGF-beta 1 or total TGF-beta 2 levels was found in these groups. Our study suggests that lower GDNF levels might be involved in the pathophysiology of mood disorders, although this preliminary study has several limitations.