Objective:To establish practical and efficient skin photoaging model in Sprague-Dawley(SD)rat and to investigate the evaluation standards. Methods:The SD rats were randomly divided into normal control group and model group

8 rats in each group.The dorsal skin of rats in model group was irradiated with increasing doses of simulated solar light combined ultraviolet-A and ultraviolet-B everyday for 10 weeks. After irradiation

visible changes

histological and ultrastructural features

biochemical indicators were detected. Results:After 10 weeks’ irradiation

the animal skin of model group became coarse and lack of elasticity. Visible deep wrinkles were observed. The wrinkle grading scale indicated the development of wrinkling. Histological alterations included epidermis thickening

hyperplasia of glands

elastosis and loss of collagen. Meanwhile

increasing number of senescent and apoptotic cells and structure destruction of dermis were seen in ultrastructure. Compared with those of the control group

there was a statistical significant increase in the content of MDA[(10.43 ± 5.67)nmol/mgprot

P=0.009]

a decrease in the content of Hyp [(7.37 ± 1.15)μg/mg

P=0.010] in skin tissue of model group

while SOD activity had no obvious difference[(21.09 ± 8.60)U/mgprot

P=0.401]. Conclusion:These typical features demonstrate the successful establishment of skin photoaging model in SD rat. Moreover

it provides comprehensive and systematic evaluation standards for photoaged skin.