Figure 4.

METH and brain ammonia. Rats were treated with METH (10 mg/kg × 4, i.p., every 2 h) or saline (1 ml/kg × 4, i.p., every 2 h) and lactulose (5.3 g/kg, p.o., every 12 h) or vehicle (8 ml/kg, p.o., every 12 h). During drug treatment (arrows denote injections), striatal ammonia concentration was measured using in vivo microdialysis. Vehicle plus METH treatment significantly increased brain ammonia concentrations starting at time point 5 and lactulose pretreatment attenuated this increase (*p < 0.05). Baseline, 29.34 ± 5.33 μm. (n = 8–10 rats per group). Lac, lactulose; Sal, saline; Veh, vehicle.