Fig. 1.
a Tissue concentrations of [3H]TCl in adult, middle-aged and aged mice after i.v. administration of 1 mg/kg body weight. Animals were euthanized 2 h after drug application, and organ drug concentrations were determined by liquid scintillation counting. Data represent means ± SD of three to eight animals per group. *Significantly different drug concentrations (P < 0.05). b Relative mRNA expression levels of the BBB markers mdr1a P-gp, claudin-5, and occludin in the brain of adult and aged mice analysed by quantitative real-time PCR