Figure 4.

Effect of theanine intake on mRNA expression of SAMP10 and ddY mice under group or confrontational housing. (a) Indoleamine-2,3-dioxygenase (IDO); (b) Tryptophan-2,3-dioxygenase (TDO); (c) Arginase; (d) Histidine decarboxylase (HDC). Mice were housed confrontationally for one month after single housing for one month (closed column). Group-housed mice were kept in a group of four for two months (open column). Mice ingested theanine (20 µg/mL, 6 mg/kg) or water (control) for two months (n = 4, *, p < 0.05).