Objective: To analyze the variation of expression of proline-rich tyrosine kinase 2 (Pyk2) in the oxygen-induced retinal neovascularization mice model.
Methods: Experimental study. One hundred and forty-four C57BL/6J mice were divided equally into the hyperoxia group and the control group. In the hyperoxia group, 72 mice (7-day-old) were exposed to (75 ± 2)% oxygen for 5 days and then moved to room air;in the control group, 72 mice were simply raised in room air. These mice were sacrificed on the 12(th), 14(th), 17(th) days and their eyeballs were collected for the preparation of pathological section, retina flat mounting and RNA extraction. The expression of Pyk2 and vascular endothelial growth factor (VEGF) mRNA in the retina were measured by real-time PCR. ANOVA was used in conjunction with SNK-q test to assess statistical significance at different time within groups; t-test was used to assess statistical significance between two groups at the same time point.
Results: Pathological sections showed that there were many endothelial cell nucleus and vascular buds on the 14(th) day (15.36 ± 3.69) and 17(th) day (29.63 ± 4.69) in hyperoxia group. There was significant difference between the control group (0.97 ± 1.00, 0.83 ± 0.79) and hyperoxia group (t(14 d) = -20.629, P(14 d) = 0.000; t(17 d) = -33.814, P(17 d) = 0.000). Retina flat mounting showed that on the 12(th) day, hyperoxia group showed vascular occlusion, vasoconstriction and large non-perfusion areas, neovascularization appeared and reached the peak on the 17(th) day. Real-time PCR showed that on the 12(th) day in hyperoxia group, Pyk2 mRNA (0.05 ± 0.03) and VEGF mRNA (0.10 ± 0.06) were lower (Pyk2: t = 15.706, P = 0.000; VEGF: t = 15.911, P = 0.000). However, on the 14(th) day and the 17(th) day, Pyk2 mRNA(1.11 ± 0.22, 1.68 ± 0.30) and VEGF mRNA (2.10 ± 0.41, 4.85 ± 0.46) increased significantly (Pyk2: t(14 d) = -3.376, P(14 d) = 0.007; t(17 d) = -7.358, P(17 d) = 0.000;VEGF, t(14 d) = -6.904, P(14 d) = 0.000; t(17 d) = -19.667, P(17 d) = 0.000).
Conclusion: Comparing to the control group, expression of Pyk2 in retinal tissue increases on the 14(th) day and 17(th) day in the hyperoxia group, indicating that the expression of Pyk2 is correlated with neovascularization.