Neuroglobin in normal retina and retina from eyes with advanced glaucoma.

BACKGROUND: Neuroglobin is a neurone specific respiratory protein that reversibly binds oxygen. Neuroglobin was discovered in 2000, initially in brain and later, at a 100 times greater concentration, in mouse retina. This protein may be involved in oxygen transport, and/or protection against oxidative stress or premature apoptosis. AIM: To examine the expression of neuroglobin in normal human retina and also in retina from eyes with advanced glaucoma, where hypoxia and ischaemia may be pathological factors. METHODS: Immunofluorescence and electron microscopy were used to examine sections of normal human retina and retina from eyes with end-stage glaucoma. RESULTS: Staining for neuroglobin was present in the plexiform layers and the photoreceptor inner segments in human retina, and increased expression was found to occur in these areas, as well as in the nuclear layers in advanced glaucoma. Much less staining for neuroglobin was present in the other retinal layers. CONCLUSION: Neuroglobin is found in those layers of the human retina that are rich in mitochondria and/or synapses, and consume the highest amount of oxygen. Neuroglobin may be involved in oxygen supply to mitochondria, or in protection from oxidative stress or apoptosis. Neuroglobin expression is increased in advanced glaucoma, and it may protect against hypoxic, ischaemic or oxidative stress, which are thought to be pathological factors that affect the retina in glaucoma.