Figure 1.

Effect of ammonia on systemic METH-induced increases in extracellular glutamate: rats were treated with METH (10 mg/kg, q 2 h × 4) or saline (1 ml/kg, q 2 h × 4) and lactulose (5.3 g/kg every 12 h) or vehicle (8 ml/kg every 12 h). During METH treatment (arrows denote injections), striatal glutamate concentration was monitored using in vivo microdialysis. Vehicle+METH treatment significantly increases brain glutamate concentrations starting at timepoint 6. Lactulose pretreatment blocks the increase. (*P<0.05; n=8–10 rats per group).