Brain derived neurotrophic factor gene mRNA and protein expression in patients with bipolar disorder

Abstract

Objective To explore the association of peripheral brain-derived neurotrophic factor (BDNF) gene expression and serum protein levels with bipolar disorder (BPD). Methods The real-time quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) with TaqMan MGB was used to analyze the BDNF gene mRNA expression in peripheral leukocytes of 61 patients with BPD［32 cases with bipolar mania(BM), 29 with bipolar depression(BD)］ and 61 healthy controls. The serum BDNF level was measured with enzyme-linked immunosorbent assay (ELISA) method. The symptoms of the patients were assessed with the Hamilton Depression Rating Scale-17(HAMD17) and Young Mania Rating Scale (YMRS). Results (1) The BDNF gene mRNA expression level in BPD group (0.0077±0.0019) was significantly lower than that in control group (0.0096±0.0028) (t=-3.74, P 0.05). (2) BDNF serum levels in BPD group (2.80±0.19) was lower than that in control group (2.99±0.49) (t=-2.90, P 0.05). (3) Neither the expression levels nor serum levels of BDNF in BM were correlated with YMRS (P>0.05), and the same result was found in BD group (P>0.05). Conclusions The findings suggest that the decreased BDNF levels may be involved in the pathophysiology of BPD, while BDNF levels might not have polarized changes in different status of episodes. Key words: Bipolar disorder; Brain-derived neurotrophic factor; Gene expression