Journal Article

Selective Over-Expression of Endothelin-1 in Endothelial Cells Exacerbates Inner Retinal Edema and Neuronal Death in Ischemic Retina

Cheung, Simon S. F., Leung, Justin W. C., Chung, Sookja K., Chung, Stephen S. M., Lo, Amy C. Y., Lam, Karen S. L., Lam, Amy K. M.

2011

Overview

The level of endothelin-1 (ET-1), a potent vasoconstrictor, was associated with retinopathy under ischemia. The effects of endothelial endothelin-1 (ET-1) over-expression in a transgenic mouse model using Tie-1 promoter (TET-1 mice) on pathophysiological changes of retinal ischemia were investigated by intraluminal insertion of a microfilament up to middle cerebral artery (MCA) to transiently block the ophthalmic artery. Two-hour occlusion and twenty-two-hour reperfusion were performed in homozygous (Hm) TET-1 mice and their non-transgenic (NTg) littermates. Presence of pyknotic nuclei in ganglion cell layer (GCL) was investigated in paraffin sections of ipsilateral (ischemic) and contralateral (non-ischemic) retinae, followed by measurement of the thickness of inner retinal layer. Moreover, immunocytochemistry of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS) and aquaporin-4 (AQP4) peptides on retinal sections were performed to study glial cell reactivity, glutamate metabolism and water accumulation, respectively after retinal ischemia. Similar morphology was observed in the contralateral retinae of NTg and Hm TET-1 mice, whereas ipsilateral retina of NTg mice showed slight structural and cellular changes compared with the corresponding contralateral retina. Ipsilateral retinae of Hm TET-1 mice showed more significant changes when compared with ipsilateral retina of NTg mice, including more prominent cell death in GCL characterized by the presence of pyknotic nuclei, elevated GS immunoreactivity in Müller cell bodies and processes, increased AQP-4 immunoreactivity in Müller cell processes, and increased inner retinal thickness. Thus, over-expression of endothelial ET-1 in TET-1 mice may contribute to increased glutamate-induced neurotoxicity on neuronal cells and water accumulation in inner retina leading to edema.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Accumulation / Aging / Agriculture / Analysis / Anatomy & physiology / Animals / Aquaporin 4 / Aquaporin 4 - metabolism / Aquaporins / Biology / Blood-brain barrier / Brain research / Cell Death / Cell Nucleus - metabolism / Cell Nucleus - pathology / Cellular structure / Cerebral blood flow / Diabetes / Diabetic retinopathy / Edema / Embolisms / Endothelial cells / Endothelial Cells - metabolism / Endothelin / Endothelin 1 / Endothelin-1 - genetics / Endothelin-1 - metabolism / Endothelium / Genetic engineering / Glial cells / Glial fibrillary acidic protein / Glial Fibrillary Acidic Protein - metabolism / Glutamate / Glutamate-ammonia ligase / Glutamate-Ammonia Ligase - metabolism / Glutamine / Heart / Hypertension / Immunocytochemistry / Immunohistochemistry / Immunoreactivity / Intermediate filament proteins / Investigations / Ischemia / Ischemia - enzymology / Ischemia - pathology / Male / Medicine / Metabolism / Mice / Neurons / Neurotoxicity / Nuclei (cytology) / Occlusion / Overexpression / Oxidative stress / Papilledema - genetics / Papilledema - pathology / Paraffin / Peptides / Permeability / Physiological aspects / Physiology / Receptor, TIE-1 - metabolism / Reperfusion / Retina / Retina - enzymology / Retina - pathology / Retinal Ganglion Cells - metabolism / Retinal Ganglion Cells - pathology / Retinal Neurons - enzymology / Retinal Neurons - metabolism / Retinal Neurons - pathology / Retinopathy / Reverse Transcriptase Polymerase Chain Reaction / RNA, Messenger - genetics / RNA, Messenger - metabolism / Rodents / Thickness / Transgenic mice / Up-Regulation - genetics / Veins & arteries