Levels of Vascular Endothelial Growth Factor-A165b (VEGF-A165b) are Elevated in Experimental Glaucoma

Purpose: Although ischemia has previously been suggested to contribute to the pathogenesis of glaucoma, neovascularization is not implicated in glaucoma. Because vascular endothelial growth factor-A (VEGF-A) is a key mediator in neovascularization response, we investigated the levels of the major pro-angiogenic (VEGF-A164) and anti-angiogenic VEGF-A subtypes (VEGF-A165b) in the retina during experimental glaucoma. Methods: Glaucoma was induced unilaterally in rats by injecting 1.9 M hypertonic saline solution in the episcleral veins. The contralateral eye served as the control. The intraocular pressure (IOP) of each eye was measured via Tonopen in conscious rats. Eyes were enucleated either on the 5th or the 10th day of elevated IOP. Whole retinal lysates were separated by SDS–PAGE and transferred to PVDF membranes. Levels of VEGF-A164 and VEGF-A165b were analyzed by western blotting using specific antibodies. In a different group of rats, retinal ganglion cells were retrogradely labeled by injecting Fluorogold in the superior colliculus a week before the induction of glaucoma. After the eyes were enucleated on the fifth day of elevated IOP, posterior eye cups were sectioned using a cryostat. Levels and localization of VEGF-A164 and VEGF-A165b were examined in retinal sections by immunohistochemistry. Results: VEGF-A164 levels remained unchanged between the control and glaucomatous retinas after five days (p=0.341) and 10 days of elevated IOP (p=0.117). The presence of the anti-angiogenic VEGF-A isoform has not been previously reported in the rat. An antibody specific to VEGF-A165b detected the anti-angiogenic protein in the rat retina. VEGF-A165b levels were significantly increased (2.33±0.44 fold, p=0.014) in the glaucomatous retinas compared to those in controls after five days of elevated IOP. VEGF-A165b levels were not different (p=0.864) between the control and glaucomatous retinas following 10 days of elevated IOP. Expression of both VEGF-A164 and VEGF-A165b were observed in the retinal ganglion cells (RGC) and inner nuclear layer (INL). Conclusions: Five day elevation of IOP leads to an increase in the anti-angiogenic VEGF-A165b levels but not in the pro-angiogenic VEGF-A164 levels in the glaucomatous retina. VEGF-A165b levels return to baseline after 10 days of elevated IOP, and VEGF-A164 levels remain unchanged. We speculate that the short-term elevation of VEGF-A165b levels and/or the unchanged levels of VEGF-A164 contribute to the lack of neovascularization in the glaucomatous retina

The Hippocampus and Memory for “What,” “Where,” and “When”

Previous studies have indicated that nonhuman animals might have a capacity for episodic-like recall reflected in memory for “what” events that happened “where” and “when”. These studies did not identify the brain structures that are critical to this capacity. Here we trained rats to remember single training episodes, each composed of a series of odors presented in different places on an open field. Additional assessments examined the individual contributions of odor and spatial cues to judgments about the order of events. The results indicated that normal rats used a combination of spatial (“where”) and olfactory (“what”) cues to distinguish “when” events occurred. Rats with lesions of the hippocampus failed in using combinations of spatial and olfactory cues, even as evidence from probe tests and initial sampling behavior indicated spared capacities for perception of spatial and odor cues, as well as some form of memory for those individual cues. These findings indicate that rats integrate “what,” “where,” and “when” information in memory for single experiences, and that the hippocampus is critical to this capacity

Global Gene Expression Changes in Rat Retinal Ganglion Cells in Experimental Glaucoma

This is a report of gene array analysis of glaucomatous retinal ganglion cells isolated by laser capture microdissection. Several novel and unexpected pathways were identified that are influenced by elevation of intraocular pressure

Anti-VEGF-A antibody does not recognize VEGF-A : Incubation with VEGF-A antibody

This antibody recognizes the VEGF-A monomer (22.5 kDa) and dimer (45 kDa) in control and glaucomatous retinas (first two lanes). VEGF-A antibody does not recognize 25 ng, 100 ng, or 250 ng of VEGF-A recombinant protein in the same membrane (last three lanes). : Incubation of the same membrane with the anti-VEGF antibody after stripping. The anti-VEGF antibody recognizes VEGF-A recombinant protein at all concentrations.<p><b>Copyright information:</b></p><p>Taken from "Levels of vascular endothelial growth factor-A (VEGF-A) are elevated in experimental glaucoma"</p><p></p><p>Molecular Vision 2008;14():1517-1524.</p><p>Published online 18 Aug 2008</p><p>PMCID:PMC2518529.</p><p></p

Immunohistochemical analysis of VEGF-A expression in the glaucomatous retina after five days of elevated IOP

-: Negative control. Some non-specific staining of blood vessels in the RGC and the INL was observed. -: VEGF-A staining of the normal retina (n=4). VEGF-A was present in the RGC and the INL. -: VEGF-A staining of the glaucomatous retina (n=4). Staining was detected in the RGC and INL. VEGF-A levels did not differ between the normal and glaucomatous retinas.<p><b>Copyright information:</b></p><p>Taken from "Levels of vascular endothelial growth factor-A (VEGF-A) are elevated in experimental glaucoma"</p><p></p><p>Molecular Vision 2008;14():1517-1524.</p><p>Published online 18 Aug 2008</p><p>PMCID:PMC2518529.</p><p></p