1-Methyl-tryptophan protects mice from central lipopolysaccharide-induced depression-like behaviors. (a) Mice given 1-methyl-tryptophan (1MT) or saline had similar decreases in body weight in response to central lipopolysaccharide (LPS, 10 ng). (b) 1MT-treated mice maintained sucrose preference following intracerebroventricular LPS treatment and (c) were protected from LPS-induced increase in tail suspension test (TST) immobility as in wild-type mice. Data are average ± standard error of the mean. *P <0.05, **P <0.01. n = 6 mice per group.