RESUMEN
<p><b>OBJECTIVE</b>To study the effect of laminarin polysaccharide (LP) on the activity of matrix metalloproteinase of photoaging skins.</p><p><b>METHOD</b>Kunming SPF mice were prepared with back hair shaved, and randomly divided into the control group, the model group, the LP low does group (LP-L, 1 mg x kg(-1)), the LP high dose group (LP-H, 5 mg x kg(-1)) and the Vit E (100 mg x kg(-1)) group. They were abdominally injected with drugs twice on a daily basis. Except for the control group, all groups were exposed to ultraviolet rays for 1 hour every day, five times on a weekly basis, with accumulated exposure dose of UVB being 21.60 J x cm(-2) and accumulated exposure dose of UVA being 84.02 J x cm(-2). Eight weeks later, exposed back skins were collected to detect thickness of dermis by HE stain, content of hydroxyproline (Hyp) by chemical colorimetry, and serum MMP-1 and TIMP-1 content by ELISA. In addition, matrix metalloproteinase-1 (MMP-1) mRNA and relative content of tissue inhibitor of metalloproteinase-1 (TIMP1) mRNA was analyzed with Real-time PCR.</p><p><b>RESULT</b>Compared with the model group, the LP-H group could significantly increase the thickness of dermis, skin Hyp content and serum TIMP-1 level, and decrease relative content of MMP-1 mRNA in skin and MMP-1 content in serum.</p><p><b>CONCLUSION</b>LP can regulate the metabolism of collagen photoaging skins by adjusting the activity of matrix metalloproteinase.</p>