| ObjectiveVascular endothelial growth factor ( VEGF) is a glycoprotein that has the capability to increase vascular proliferation and permeability and can participate in various inflammation disease ; integrins are a family of transmembrane cell surface glycoproteins and those with the betal-subunit function in both cell-to-cell and cell-to substrate adhesion. Integrin pi can regulate angiogenesis promoted by VEGF and the two glycoproteins may play roles together during the progress of periapical inflammation. For the first time, this research adopt immuno-histochemistry method to detect the expression and distribution of VEGF and integrin(31 during the development of periapical lesions, and measure the integrated optical density average value (IODA) with image analysis instruments of the VEGF and integrin pi positive sites to observe the expression trend, thus provide more insights into the mechanisms involved in periapical lesion formation.Methods10 SD rats are randomly divided into 5 groups, 2 rats were used as the control group, the other 8 rats were anesthetized and perfused through the left ventricle with 4% paraformaldehyde at 7, 14, 21 and 28 days separately after pulp exposure. The maxillas were fixed in 4% paraformaldehyde beyond 24 hours, decalcified by EDTA for 3 weeks and embedded in paraffin. 10 sections wereobtained with the thickness of 7 m. Among the 10 sections, 2 sections were stained with heatoxylin-eosin, 4 sections were used for VECF immunohistochem-ical staining, and 4 sections were used for integrin l immunohistochemical staining. The sections were observed by light microscopy and examined the VECF and integrin 1 positive site IODA level with image analysis instruments in the periapical tissue, then the results were analyzed by statistical method.Results1. Histology observation: All of the periapical tissues for control group were free of inflammation and bone destruction. The intensity of periapical inflammation and bone resorption increased from days 7 to 21. At days 21, periapical little abscess and granuloma can be seen, bone destruction was most significant and the number of Howship' lacunae were considerably increased. At 28 days, the apical abscess enlarged and the fibrous tissue started to proliferate in the periapical tissue.2. Imunohistochemistry observation;2. 1 VEGF immunohistochemical staining: A weak immunopositive cyto-plasmic reaction for VEGF was observed in the fibroblasts, endothelial cells, and few of the osteocytes in the normal periapical tissue. At 7, 14 days , the massive inflammatory infiltration showed a strong immunostaining reactivity, and most of the osteocytes presented a moderate staining. At 21, 28 days, in a periapical abscess with dense infiltration inflammatory cells, intensive staining for VEGF was observed, whereas the proliferated blood vessels, endothelial cells and fibroblasts showed a moderate staining. Strong positivity for VEGF was seen in osteocytes and the vessels in the Howship' lacunae, whereas positive reaction was seen in some of the osteoclasts and osteoblasts.2. 2 Integrinpl immunohistochemical staining: An extensive immunopositive reaction for integrinpl was observed in the fibroblasts, endothelial cells, collagen matrix , cementum cells and osteocytes. Hie intensity of staining in the periapical connective tissue was increased and the massive inflammatory infiltration showed a strong immunostaining reactivity from days 7 to 21. Strong positiv-ity for integrinpl was seen in osteocytes, osteoblasts, osteoclasts and the vessels in the Howship' lacunae from days 0 to 14, but the intensity of staining was decreased from days 21 in the periapical alveolar bone.3. Image analysis result: The IODA value of VEGF positive sites in the periapical tissue had a tendency to increase gradually following dental pulp expose time. The IODA value of integrinpl positive sites in the periapical connective tissue was increased from day 0 to days 21 and decreased at days 28 , whereas the IODA value in the periapical alveolar...
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