BDNF and Anxiety: Desbonnet et al. studied the rats who were given antibiotics from weaning and found their intestinal microbiota changed: they had relatively less Firmicutes and Bacteroidetes, relatively more Cyanobacteria and Proteobacteria, and reduced anxiety in light-dark box test, cognition deficient, changed tryptophan metabolic pathway, reduced expression of BDNF, oxytocin and antidiuretic hormone in the brain of adult rats.