Abstract: Konjac mannan-oligosaccharides (KMOS) are a kind of important prebiotic. In present study, in order to investigate the effects of KMOS on emotional neural behaviors and the hippocampal neuron density in mice, we divided 50 adult male KM mice into 5 groups， and fed them with KMOS of 0 (control), 650, 1400, 3000 and 6500 mg/kg (i.g.) for consecutive 30 d, and then the mice were tested in the open-field, elevated plus maze (EPM) and forced swimming tasks. At last, their brains were sectioned and stained for hippocampal neuron density counting. Results showed that, the ventral hippocampal CA3 neuron density of KMOS group (6500 mg/kg) increased significantly (P<0.01, vs. control) and positively correlated with the doses (P<0.01). In open field, the rearing times and center entries of KMOS groups (1400 and 3000 mg/kg) significantly increased (P<0.01, vs. control). In EPM, the open arms entries of mice in 3000 mg/kg group also increased (P<0.01, vs. control). The results suggested that long-term treatment of mice in KMOS would be involved in neuron survival in hippocampal CA3 subarea and have anxiolytic effect in mice.

Key words: Konjac mannan-oligosaccharides, hippocampus, open field, elevated plus maze, forced swimming, KM mice