Table 3.

Gut brain axis and depression

Subject	Outcome	Ref.
Germ-free mice	Germ-free (GF) mice showed impaired social interactions, anxiety and derangement of brain-derived neurotrophic factor levels	Crumeyrolle-Arias et al[83], Huo et al[85], and Kamimura et al[86]
GF and SPF mice	Exposure of GF mice and specific pathogen-free (SPF) mice to chronic restraint stress paradigm revealed an increase in open field exploration time in GF compared to SPF mice. Also, SPF mice exhibited more anxiety-like behavior than GF mice under the same external stress	Arentsen et al[84]
C57BL/6J male mice	Chronic administration of prebiotic (fructo-oligosaccharides and galacto-oligosaccharides) have been associated with antidepressant and anxiolytic effects	Kamimura et al[86]
Glutamate and non-glutamate supplemented media	Gamma amino-butyric acid (GABA)-producing Lactococcus lactis strain increased GABA production in the glutamate supplemented medium	Burokas et al[87]