The effects of different dosages of L-theanine on SPF grade Balb/KM male mice under heat treatment, including feed intake, weight, organs index, histopathological features of jejunum, activities of serum alanine aminotranferease (ALT) and aspartate aminotransferase (AST), contents of tumor necrosis factor (TNF-α), interleukin-6 (IL-6), interferon-γ (IFN-γ) in serum, content of liver homogenate malondialdehyde (MDA), activities of liver homogenate superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and histopathologica...