Year: 2008
Type: article
Abstract: Diabetic retinopathy is characterized by retinal vascular degeneration that progresses to blindness in some patients.Whereas this vasculopathy has been the focus of basic science and clinical research, the neural component of the retina is also significantly affected by diabetes, with neurodegeneration occurring prior to the appearance of vascular lesions.In human and rat models of diabetic retinopathy, functional and histological abnormalities indicate loss of retinal ganglion cells (RGCs), a type of retinal neuron of central importance to vision.However, RGC loss in murine models of diabetic retinopathy is controversial, with some studies showing such loss and others not.The methods used by these studies to estimate RGC population size are based on assumptions that may lead to inaccurate estimations.This study employs an alternative approach in which the RGC population is determined by counting all of the optic nerve axons, as each axon in the optic nerve represents one ganglion cell in the retina.An automated method for reliably counting and characterizing axons in histological sections was developed.Total axon number, axon density, and axon size in optic nerves from 32-week non-diabetic C57BL/6, streptozotocin-induced diabetic C57BL/6, and spontaneously diabetic Ins2Akita mice were compared.In optic nerves visualized by electron microscopy, total axon number does not differ between the treatment groups.Similarly, diabetes does not affect axon density.The streptozotocin-induced diabetic mice exhibit a statistically greater mean axon size than their non-diabetic (p=0.042) or Ins2Akita counterparts (p=0.032).This axonal hypertrophy may indicate underlying RGC pathology in these animals.No significant differences in any of these measures occurred when optic nerves were visualized by light microscopy, most likely due to the lower resolving power of this visualization approach.
Author: Eamon Keenan
Institution: Case Western Reserve University
Language: English
Subfield: Ophthalmology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2625639233