Background: Chronic exposure of human skin to ultraviolet B (UVB) affects the structure and function of the skin, and causing skin aging. Caffeine is hypothesized to inhibit the skin aging process through the inhibition mechanism of the Ataxia Telangiectasia and Rad3-Related–Checkpoint Kinase 1 (ATR-Chk1) pathway. This study aimed to prove that caffeine cream can increase the apoptotic cells and decrease the expression of phosphorylated ATR (Thr 1989) in the skin of male mice (Mus musculus) exposed to UVB.
Methods: This study used a randomized post-test only control group design. The subject used in this study was 36 mice and divided into two groups. The control group was treated with emulgide cream as a placebo and the treatment group was treated with cream containing 4.8% of caffeine. Both groups were exposed to UVB at a dose of 343 mJ/cm2 for 8 weeks. Skin biopsy from the central area of the back obtained after the last session and followed by an examination of apoptotic cells of epidermis using H&E staining and phosphorylated ATR (Thr 1989) expression in epidermis using immunohistochemistry.
Results: It showed that the mean number of apoptotic cells in the treatment group was higher (2.15±0.43 cells/hpf) than the control group (0.81±0.55 cells/hpf) (P<0.001). The mean phosphorylated ATR (Thr 1989) expression in the treatment group was lower (8.03±3.91%) than the control group (23.62±4.39%) (P<0.001).
Conclusion: The administration of caffeine cream can increase apoptosis and decrease phosphorylated ATR (Thr 1989) expression in the UVB-exposed male mice (Mus musculus) skin epidermal cells.