Topical axitinib is a potent inhibitor of corneal neovascularization

Background: This study evaluated the effects of topically applied axitinib, a tyrosine kinase inhibitor, in an experimental model of corneal neovascularization (CNV). Methods: A total of 48 New Zealand rabbits were used. CNV was induced by placing five silk sutures in the upper cornea of one eye per rabbit. Rabbits were randomized into four groups (12 rabbits each): 0.9% saline (control group), 0.02 mg/mL axitinib, 0.35 mg/mL axitinib and 0.5 mg/mL axitinib groups. All treatments were administered three times daily for 14 days. Photographs were taken using a slit lamp on days 7 and 14. The area of neovascularization was measured in mm2, as the percentage of total corneal area and as the percentage of corneal surface covered by sutures (SCS). Results: On day 14, the CNV area in the control group (31.50 ± 7.47 mm2; 115.00 ± 22.55% of the corneal SCS) was larger than that in the 0.02 mg/mL axitinib group (19.20 ± 8.92 mm2; 73.89 ± 34.98%), the 0.35 mg/mL axitinib group (8.83 ± 3.92 mm2; 31.90 ± 13.59%) and the 0.5 mg/mL axitinib group (5.12 ± 3.97 mm2; 18.38 ± 13.65%). Compared with saline, CNV was inhibited 39.04% by 0.02 mg/mL axitinib, 71.96% by 0.35 mg/mL axitinib and 84.73% by 0.5 mg/mL axitinib. Conclusion: Topical administration of the three axitinib concentrations inhibited CNV in rabbits, blocking both vascular endothelial growth factor and platelet‐derived growth factor pathways. Axitinib at 0.5 mg/mL induced profound inhibition of corneal angiogenesis.Publication of this article was supported in part by a research grant from the Institute of Health Carlos III (PS09/02407), Madrid, Spain

La transducción visual

La transducción visual o fototransducción es el proceso mediante el cual un fotón genera una respuesta nerviosa en los fotorreceptores. La estimulación de la rodopsina de los bastones y las opsinas de los conos activan una compleja cascada de reacciones enzimáticas y bioquímicas como respuesta a la luz, induciendo el cierre de los canales catiónicos de la membrana del fotorreceptor. El potencial de membrana de los fotorreceptores se hiperpolariza, causando una reducción de la cantidad de neurotransmisor liberado por el terminal del fotorreceptor hacia las neuronas post-sinápticas. Determinadas mutaciones genéticas o factores ambientales pueden alterar el normal funcionamiento de los fotorreceptores provocando el desarrollo de numerosas enfermedades distróficas retinianas.La transducció visual o fototransducció és el procés mitjançant el qual un fotó genera una resposta nerviosa en els fotoreceptors. L’estimulació de la rodopsina dels bastons i les opsines dels cons activen una complexa cascada de reaccions enzimàtiques i bioquímiques com a resposta a la llum, induint el tancament dels canals catiònics de la membrana del fotoreceptor. El potencial de membrana dels fotoreceptors s’hiperpolaritza, causant una reducció de la quantitat de neurotransmissor alliberat pel terminal del fotoreceptor cap a les neurones postsinàptiques. Determinades mutacions genètiques o factors ambientals poden alterar el normal funcionament dels fotoreceptors provocant el desenvolupament de nombroses malalties distròfiques retinals.Visual phototransduction is a process by which light is converted into neural response in photoreceptors. Stimulation of rhodopsin in rods and opsin in cones activate a complex cascade of enzymatic and biochemical reactions in response to light, inducing the closure of cation channels in photoreceptor membrane. The membrane potential of a photoreceptor is hyperpolarized and a reduction in the amount of neurotransmitter released by the photoreceptor terminal onto postsynaptic neurons is caused. Genetic mutations or environmental factors can disturb the normal functioning of photoreceptors resulting in the development of many dystrophic retinal diseases