The Effects of Bevacizumab Treatment in a Rat Model of Retinal Ischemia and Perfusion Injury

Purpose: To create a model of an ischemic retina with temporary ischemia and reperfusion (IR) and to examine the possible antiapoptotic and neurodegenerative effects of a vascular endothelial growth factor (VEGF) antagonist.

Methods: Three groups were formed. Rats were subjected to continued ischemia for 45 min, and then reperfusion was allowed for 2 days. For the first group, ischemia was induced, but an anti-VEGF agent was not administered. For the second group, 2 days before ischemia, 0.005 ml (0.125 mg) of bevacizumab was administered intravitreally, and then the ischemic model was created. The last group's intraocular pressure was not increased as in the control group, and only a cannula was introduced into the anterior chamber through the cornea. Six animals from each group were subjected to histomorphometry, and four were subjected to immunohistochemical and histopathologic examinations. For a histomorphometric examination, the number of cells in the retinal ganglion cell (RGC) layer was counted using the optical dissector method. For immunohistochemistry, the vascular endothelial growth factor receptor-2 (VEGFR-2) levels and apoptosis were examined in the retinal and choroidal tissue.

Results: It was observed that in an IR injury, bevacizumab reduces the death and apoptosis of cells in the RGC layer. It was also identified that although bevacizumab is a large molecule, the agent affects the choroid and reduces the amount of VEGFR-2 in this tissue.

Conclusions: IR may be used as a model of ischemic retinopathy that includes VEGF-dependent vascular permeability and neurodegeneration. Although VEGF is a neurotrophic molecule, in IR injury, treatment with bevacizumab, which is an anti-VEGF agent, decreases apoptosis, showing that excess function of this molecule can be hazardous.