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Behav Brain Res. 2016 Feb 1;298(Pt B):202-9. doi: 10.1016/j.bbr.2015.10.046. Epub 2015 Oct 29.

Alteration of behavior and monoamine levels attributable to Lactobacillus plantarum PS128 in germ-free mice.

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Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 11221, Taiwan.
National Laboratory Animal Center, National Applied Research Laboratories, Taipei 115, Taiwan.
Institute of Anatomy and Cell Biology, National Yang-Ming University, 155, Section 2, Linong Street, Taipei 11221, Taiwan. Electronic address:
Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 11221, Taiwan; Probiotic Research Center, National Yang-Ming University Business Center of Industry-Academia Liaison, Taipei 11221, Taiwan. Electronic address:


Probiotics, defined as live bacteria or bacterial products, confer a significant health benefit to the host, including amelioration of anxiety-like behavior and psychiatric illnesses. Here we administered Lactobacillus plantarum PS128 (PS128) to a germ-free (GF) mouse model to investigate the impact of the gut-brain axis on emotional behaviors. First, we demonstrated that chronic administration of live PS128 showed no adverse effects on physical health. Then, we found that administration of live PS128 significantly increased the total distance traveled in the open field test and decreased the time spent in the closed arm in the elevated plus maze test, whereas the administration of PS128 had no significant effects in the depression-like behaviors of GF mice. Also, chronic live PS128 ingestion significantly increased the levels of both serotonin and dopamine in the striatum, but not in the prefrontal cortex or hippocampus. These results suggest that the chronic administration of PS128 is safe and could induce changes in emotional behaviors. The behavioral changes are correlated with the increase in the monoamine neurotransmitters in the striatum. These findings suggest that daily intake of the L. plantarum strain PS128 could improve anxiety-like behaviors and may be helpful in ameliorating neuropsychiatric disorders.


Anxiety; Dopamine; Germ-free mice; Lactobacillus plantarum; Locomotor; Serotonin

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