Fig. 2. Histopathological analysis of dorsal ear and back skin tissues and the anti-inflammatory effects of the TECA + AST treatment through inhibiting NF-κB in the back skin. Histopathology of dorsal ear and back skin tissues (A). PA solution was repeatedly applied to the dorsal ear and back skin during the topical application of TECA, AST and the TECA+AST combination. Histopathological changes were examined in the slide sections of dorsal ear and back skin tissues by staining with H&E followed by observation at 200× magnification (scale bars, 100 μm). Alterations in the expression of iNOS and COX-2 proteins of the back skin were measured by Western blotting (B). The effect of TECA, AST and the TECA + AST combination on NF-κB (p50 and p65) subunit translocation into the nucleus and IκBα phosphorylation in back skin cytosol (C). Equal amounts of nuclear proteins (20 μg/lane) or total proteins (20 μg/lane) were subjected to 10% SDS-PAGE, and the expressions of p50, p65, IκBα and p-IκBα proteins were detected by Western blotting using specific antibodies. Histone h1 protein and β-actin protein were used here as internal controls. Data shown are the mean ± standard deviation (n = 10).

Con, control; TECA, titrated extract of Centella asiatica; AST, astaxanthin; NF-κB, nuclear factor-κB; PA, phthalic anhydride; H&E, hematoxylin and eosin; iNOS, inducible nitric oxide synthase; COX, cyclooxygenase; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis.