Abstract:

Objective  To investigate the expression of brain-derived neurotrophic factor (BDNF) in hippocampus of the maternally separated animals, and to explore the regulatory role of hippocampal BDNF on the impact of anxiety to visceral hypersensitivity. Methods  We used maternal separation (MS)   to study irritable bowel syndrome (IBS). The anxiety of rats was observed and measured in open-field test, and then the visceromotor responses to colorectal balloon distension (CRD) were assessed by abdominal withdrawal reflex (AWR). The expression of BDNF in hippocampus was determined by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. The correlations among anxiety, visceral hypersensitivity and the expression of BDNF in hippocampus were analyzed in MS rats. Results  Compared with control rats, MS rats showed more anxieties (P<0.05), and had more visceral pain (P<0.05) in response to each CRD pressure gradient (20, 40, 60 and 80mmHg). The protein expression of BDNF was increased in hippocampus of MS rats compared with controls (P<0.05), especially in the CA1 and CA3 areas of hippocampus (P<0.05). The level of anxiety was positively correlated with the hypersensitivity in MS rats, and the expression of BDNF in the hippocampus was positively correlated not only with the level of anxiety but also with hypersensitivity. Conclusion  Upregulation of BDNF expression in hippocampus plays an essential role in anxiety-induced visceral hypersensitivity in IBS.

Key words: Anxiety, Maternal separation, Visceral hypersensitivity, Brain-derived neurotrophic factor