Effects of RF exposure on the levels of four amino acid neurotransmitters in hippocampus and cortex. (a) hippocampus (Glu: t = 0.915, df = 16, P = 0.374; GABA: t = 2.673, df = 16, P = 0.017; ASP: t = 2.266, df = 16, P = 0.038; Gly: t = 1.132, df = 16, P = 0.275), (b) cortex (Glu: t = 0.659, df = 18, P = 0.518; GABA: t = 2.939, df = 18, P = 0.009; ASP: t = 2.173, df = 18, P = 0.043; Gly: t = 0.889, df = 17, P = 0.386), (c) the ratio of Glu/GABA in hippocampus (t = 1.146, df = 16, P = 0.269), (d) the ratio of Glu/GABA in cortex (t = 1.342, df = 18, P = 0.196). The data are presented as mean ± SD, * P < 0.05, ** P < 0.01, compared with the sham group.