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Scientific Tracks Abstracts: JCEO
The immature retina is extremely susceptible to hypoxic-ischemic conditions resulting in the development of retinopathy .Hypoxia is an underlying factor in many conditions such as compromised pulmonary function and cyanotic heart disease which are important aetiological factors in the development of retinopathy. This study aimed to examine vascular changes in the retina of neonatal rats subjected to hypoxia (5% oxygen+95% nitrogen) for 2 h. The expression of endothelial nitric oxide synthase(eNOS) and vascular endothelial growth factor (VEGF) was examined in the retina along with ultrastructure of the blood vessels. Increased mRNA and protein expression of VEGF and eNOS was observed in hypoxic retinas. Specific localization of VEGF was observed in the astrocytes closely associated with the blood vessels. The blood vessels expressed eNOS immune reactivity and appeared to be dilated as compared to the vessels in the controls but the tight junctions between the endothelial cells remained intact. Endothelial cells often showed vacuoles and multivesicular aggregations in the cytoplasm following the hypoxic injury. Increased leakage of intraperitoneally administered fluorescent tracer rhodamine isothiocyanate was detected in the retina of hypoxic rats suggesting increased permeability of the blood vessels which may be mediated by VEGF and eNOS. The structural changes in the endothelial cells may reflect impairment of transendothelial transport in the developing retina. We suggest that vascular changes may be a major factor contributing to degenerative changes such as retinalganglion cell (RGC) death following a hypoxic injury. Administration of melatonin, an antioxidant drug,was beneficial in suppressing the production of VEGF and vascular permeability as well reversing the structural changes in he blood vessels and RGC.
Charanjit Kaur completed her Ph.D from the Department of Anatomy, Faculty of Medicine, National University of Singapore.She is an Associate Professor and Research Director at the Department of Anatomy. She has published more than 117 papers in reputed journals, has w ritten many book chapters and is a reviewer for more than 65 journals (e.g Brain, FASEB Journal,Pediatrics, Investigative Ophthalmology and Visual Science and many more). She has reviewed grants for Austrian Science Fund, Welcome Trust, Swiss National Science Foundation, Research G rants Council Hong Kong among many others. She is serving as a section editor/editorial board member on many journals.