Resistant starch-Capric acid effectively improves lipopolysaccharide-induced depressive behaviour by protecting the intestinal microbiota barrier and inhibiting inflammatory responses

Previous studies have found that gut flora, immunity and neuroinflammation play key roles in the pathogenesis of depression, and fatty acids are neuroprotective. The present study aimed to reveal the effects of capric acid intake on LPS-induced depression-like behavior and its underlying mechanisms. Male ICR mice were ingested with resistant starch-decanoic acid complex for 50 consecutive days. The depression model was established by injecting LPS. The results of behavioral tests showed that the mice pretreated with resistant starch capric acid complex had significantly shorter resting time in the tail suspension test; the number of crossing grids and the number of standing in the open field test were significantly increased. In addition, TNF-alpha levels in the serum of depressed mice were decreased; 5-HT levels in the hippocampus were increased. It had an ameliorative effect on the haphazard arrangement of colonic glandular cells caused by LPS, as well as nuclear condensation and eosinophilic degeneration of hippocampal neurons. The 16S rRNA results indicated that pretreatment with resistant starch capric acid complex reversed the imbalance of the bacterial flora associated with depression, decreased the species richness, and the homogeneity of the intestinal flora was improved so that the composition of intestinal microorganisms was in line with that of the normal group.