The Expression Of VEGF And VEGFR In A Rat Model Of Retinopathy Of Prematurity

ObjectiveTo explore the expression of VEGF and its receptors (flt-1 and flk-1) in the retina ofretinopathy of prematurity(ROP), and the relation with the alteration of retinal bloodvessels.MethodsEighty-six newborn Sprague-Dawley rats were randomly divided into hyperoxia andair group (control group), then each group was distributed into 1, 3, 7 and 14 dayssubgroups. The rats in hyperoxia group inhaled 75% oxygen for 7 days; then, the ratswere returned to the room air at the age of 14 days, thus the rat model of ROP was setup. In the meantime, the rats in the control group were kept in room air. Theseanimals were sacrificed respectively after 1, 3, 7 and 14 days, then the retinal sampleswere processed and stained by HE, and the endothelial cells were marked by CD34 toobserve the change of retinal blood vessels. The expression of VEGF, flt-1 and flk-1in the retina was measured by immunohistochemistry.Results(1)On the 7th day, the retinal capillary density index( RCDI) in hyperoxia group wasless than that of control group (2.01±0.23 vs 3.20±0.43, P<0.05), but RCDI was3.99±0.43 when the rats had been returned to air for 7 days, and RCDI on the 14thday in control group was 3.62±0.56, there was significant difference between them(P<0.05) . (2)In the control group, the expression of VEGF and flk-1 was the strongest in the retina on the 7th day, the result had significant difference compared with the 1st, 14th day (P<0.05) .(3)The expression of VEGF and flk-1 on the 7th day in hyperoxia group was weaker than that of control group on the 7th day (P<0.05) . But on the 14th day in hyperoxia group, they were stronger than that of control group(P<0.05) . (4)The localization of the expression of flt-1 was changed when blood vessels altered, but there was no significant difference in expression intensity as a whole(P>0.05).ConclusionsWhen the premature retina was exposed to hyperoxia, the expression of VEGF and flk-1 were reduced, and retinal blood vessels were decreased; but the expression of VEGF and flk-1 was stronger in retina when premature rats were exposed to relatively hypoxia, and the retinal blood vessels increased significantly. We concluded that VEGF and flk-1 may play important roles in the development of retinal blood vessels and its change in ROP, However, flt-1 has less effect compared with the role of flk-1.