In in vitro studies, Choi et al. [141] identified that MV from a Gram positive probiotic native to the gut, Lactobacillus plantarum, upregulated expression of BDNF transcripts as well as proBDNF protein in HT22 hippocampal cells after the induction of depression-associated changes by glucocorticoid (GC) treatment. Here, BDNF is linked to depressive disorder.