db/db mice at age of 16 weeks were treated with rFGF21 for 10 days. BBB leakage was measured by permeability to sodium fluorescein (NaFl), and junction protein expression was measured by Western blot and immunohistochemistry. (A) BBB permeability for NaFl after rFGF21 treatment in db/db mice. (B) Representative Western blot images of junction proteins ZO-1, Occludin, Claudin-5 and VE-cadherin. (C-E) Quantification of western blot results for ZO-1, Occuldin and VE-cadherin. (F) Immunohistochemistry for VE-cadherin in db/db brain vessels after rFGF21 treatment. (G) Immunohistochemistry for occludin in db/db brain vessels after rFGF21 treatment, dashed white box show the vessels. (* p<0.05 vs. db/+; # p<0.05 vs. db/db; n=6).