Rats were pretreated with lactulose or vehicle for 2 days before treatment with Meth or saline. A) Occludin and B) claudin-5 were measured via Western Blot in isolated capillaries from cortical tissue, 24 h after Meth or saline treatment. Meth treatment significantly decreased occludin (*, p < 0.005, compared to Vehicle Saline) and claudin-5 (*, p < 0.001, compared to Vehicle Saline) protein expression, which was blocked by lactulose pretreatment (#, p < 0.001, compared to Vehicle Meth) (n = 6–13 per group). C) Representative Western Blot image of occludin, claudin-5 and α-tubulin.