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 Show more
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. Show less
Maternal separation (MS) is a widely used model of early-life stress that induces long-lasting behavioral and neurobiological alterations in offspring. Maternal exercise during pregnancy has been prop Show more
Maternal separation (MS) is a widely used model of early-life stress that induces long-lasting behavioral and neurobiological alterations in offspring. Maternal exercise during pregnancy has been proposed as a non-pharmacological strategy to counteract these adverse effects. Pregnant Wistar rats were assigned to either a sedentary or exercise group, with the exercise group having free access to a running wheel throughout pregnancy. Offspring were divided into four experimental groups: offspring of sedentary mothers without MS (SedMS-), offspring of sedentary mothers with MS (SedMS+), offspring of exercised mothers without MS (ExMS-), and offspring of exercised mothers with MS (ExMS+). Behavioral assessments, conducted in adulthood starting at postnatal day 90 (P90), included the open field, elevated plus maze, forced swim test, and contextual fear conditioning. Morphological analysis of the hippocampus was performed using isotropic fractionation to quantify total neuronal and non-neuronal cells. Epigenetic changes were evaluated through chromatin immunoprecipitation (ChIP) using anti-acetylated histone H3 and H4, followed by amplification of bdnf exons IV and VI. Maternal separation increased depressive-like behavior and impaired hippocampus-dependent memory, effects that were attenuated by maternal exercise. MS also elevated non-neuronal cell numbers and reduced neuronal cells in the hippocampus, whereas prenatal exercise reversed these alterations. No significant group differences were found in histone acetylation at the Bdnf loci examined. Maternal exercise during pregnancy mitigates behavioral and morphological deficits induced by early-life stress, supporting its neuroprotective role in preserving hippocampal integrity and function. Although no significant epigenetic changes were detected, these findings suggest that maternal physical activity may be a promising intervention to mitigate the long-term neurobiological consequences of early-life adversity. Show less