Figure 5. Melatonin pretreatment ameliorates the effect of MMP-9 on the expression of VE-cadherin, occludin, claudin-5, and ZO-1 in the BBB in different treatment groups. Cells were treated as described in the Materials and methods for observation by immunofluorescence. (A1–A8) Immunofluorescence staining of VE-cadherin; (B1–B8) Immunofluorescence staining of occludin; (C1–C8) Immunofluorescence staining of claudin-5; (D1–D8) Immunofluorescence staining of ZO-1.