BDNF Exacerbates Visceral Hypersensitivity through Hippocampal TrkB-CRF Signaling in Early-Life Stress

Irritable bowel syndrome (IBS) associated with early-life stress (ELS) commonly manifests as anxiety and visceral hypersensitivity. However, the pathogenic mechanisms underlying these effects are not fully understood. This study aims to investigate the role of brain-derived neurotrophic factor (BDNF) as a key mediator of ELS-induced changes through the brain-gut axis.

A Sprague-Dawley male maternal separation (MS) rat model was used to induce anxiety and visceral hypersensitivity associated with ELS. BDNF levels were measured in the limbic system (cingulate gyrus, amygdala, and hippocampus) and serum. The correlation between BDNF levels, anxiety, and visceral hypersensitivity was analyzed. Corticotropin-releasing factor (CRF) expression in the hippocampus and the extent of visceral hyper-sensitivity were assessed in control, MS, and MS+K252a (a BDNF receptor antagonist) groups.

MS rats exhibited higher levels of anxiety and visceral hypersensitivity compared to controls. BDNF production in the hippocampus was elevated in MS rats and positively correlated with anxiety (r = -0.78, p < 0.05) and visceral hypersensitivity (r = 0.93, p < 0.01). CRF expression, a key mediator of stress and visceral hypersensitivity, was also increased in the hippocampus of MS rats. Inhibition of BDNF signaling using K252a reduced CRF expression and alleviated visceral hypersensitivity.

This study demonstrates that BDNF may mediate ELS-induced anxiety and visceral hypersensitivity through hippocampal TrkB-CRF signaling, providing a mechanistic basis for targeting BDNF in stress-related IBS.