['Because there is evidence that certain neurotrophic factors are involved in depression and the mechanism of antidepressant treatment, it is hypothesized that neurotrophic factors may also play a functional role in the etiology of depression and treatment. Glial cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor (TGF-β)-super-family. We performed a study to assess the impact of chronic unpredictable stress (CUS) and clomipramine treatment on GDNF expression in the rat hippocampus.', 'Using a rat model of CUS-induced depression, we administered clomipramine, one of the typical antidepressants, every day for 3 weeks starting 2 weeks after the beginning of the experiment. GDNF level in the hippocampus was detected by immunohistochemsitry, Western blot analysis, and reverse transcription-polymerase chain reaction (RT-PCR). Behavioral changes were measured by forced swimming test (FST) and open field test (OFT).', 'Animals exposed to CUS showed depression-like behavior and exhibited a significant decrease in GDNF expression in the hippocampus. Chronic clomipramine treatment reversed the behavioral deficits and the decrease in GDNF levels induced by CUS.'] Does chronic clomipramine treatment restore hippocampal expression of glial cell line-derived neurotrophic factor in a rat model of depression?